Properties and uses

Contents 1 Overview 1 Uses 1 Technical support for specific applications

2 Properties 2 Chemistry 6 Product types 6 Butvar: the right resin solution 13 Compatibility 15 Insolubilizing reactions

17 Applications 17 Wire enamels 17 Surface coatings 17 Wash primers 17 Military-specification wash primers 18 Nonspecification wash primers:

B-1030 with Butvar 18 Single-package wash primer:

B-1011 with Butvar 19 Chromate-free wash primers with Butvar 20 Metal coatings 21 Wood finishes 21 Protective wash coats and sealers 21 Knot sealers

22 Adhesives 22 Structural adhesives 22 Phenolic resins 22 Epoxies and other thermosetting resins 23 High-strength bonding procedure 23 Performance characteristics 23 Adhesive strengths 24 Hot-melt adhesives 24 Textile coatings 24 Advantages as textile coating 25 Ceramic binder applications 26 Tape casting 26 Thick films 27 Toners and printing inks

28 Storage and handling 28 Storage 28 Toxicity and FDA status 28 Quality control

29 Material sources

1

Overview Polyvinyl butyral resins are employed in a wide array of industrial and commercial applications. These unique resins offer impressive performance as well as outstanding versatility.

Butvar® polyvinyl butyral resins have a combination of properties that make them key ingredients in a variety of successful formulations. Some of the properties for which Butvar is widely used are outstanding binding efficiency, optical clarity, adhesion to a large number of surfaces, and toughness combined with flexibility.

Eastman offers six grades of Butvar resins that cover a broad range of chemical and physical properties. These resins are generally well suited either as a major ingredient of a formulation or, in smaller quantities, to enhance the properties of other resins.

Uses Some of the applications in which Butvar is a vital ingredient include:

• Ceramic binders

• Inks/dry toners

• Wood coatings

• Wash primers

• Composite fiber binders

• Structural adhesives

• Other diverse uses

Technical support for specific applications Eastman offers technical support for Butvar resins and can assist you in your specific application. For more information regarding Butvar resins, to seek technical help, or to request a sample, visit www.eastman.com/butvar.

2

Properties ChemistryAcetals, such as polyvinyl butyral, are formed by the well-known reaction between aldehydes and alcohols. The addition of one molecule of an alcohol to one molecule of an aldehyde produces a hemiacetal. Hemiacetals are rarely isolated because of their inherent instability; instead, they are further reacted with another molecule of alcohol to form a stable acetal.

Polyvinyl acetals are prepared from aldehydes and polyvinyl alcohols. Polyvinyl alcohols are high-molecular-weight resins containing various percentages of hydroxyl and acetate groups produced by hydrolysis of polyvinyl acetate.

The conditions of the acetal reaction and the concentration of the particular aldehyde and polyvinyl alcohol used are closely controlled to form polymers containing predetermined proportions of hydroxyl, acetate, and acetal groups. The final product may be represented by the following stylized structure.

The proportions of A, B, and C are controlled, and they are randomly distributed along the molecule.

H

R — C + R1 — OH

O Alcohol

Aldehyde

H

R — C (— OR1)2 + H2O

Acetal

H

H C3H7

HCH2

CH2 — C

C

C

O O

PV butyral

A

H

CH2 — C

OH

PV alcohol

B

H

CH2 — C

O

C

CH3

O

PV acetate

C

H

R — C — OR + R1 — OH

OH

Hemiacetal

Alcohol

3

Table 1. Physical properties of Butvar® resins (white, free-flowing powder)

Property Units ASTM method B-72 B-74 B-76 B-79 B-90 B-98

Volatiles,a max. % — 3.5 3.0 5.0 5.0 5.0 5.0

Molecular wt (weight average in thousands)

— (1) 170–250 120–150 90–120 50–80 70–100 40–70

Solution viscosity 15% by weight

cP (2) 7,000–14,000 3,000–7,000 500–1,000 100–400 600–1,200 200–400

Solution viscosity 10% by weight

cP (2) 1,600–2,500 800–1,300 200–450 75–200 200–400 75–200

Ostwalda solution viscosity

cP (3) 170–260 37.0–47.0 18.0–28.0 9.0–16.0 13.0–17.0 6.0–9.0

Specific gravity 23°/23°C (±0.002)

— D792-50 1.100 1.100 1.083 1.083 1.100 1.100

Burning rate ipm D635-56T 1.0 1.0 1.0 1.0 0.9 0.9

Refractive index (±0.0005)

— D542-50 1.490 1.490 1.485 1.485 1.490 1.490

Water absorption (24 hours)

% D570-59aT 0.5 0.5 0.3 0.3 0.5 0.5

Hydroxyla content expressed as % polyvinyl alcohol

— — 17.5–20.0 17.5–20.0 11.5–13.5 11.0–13.5 18.5–20.5 18.0–20.0

Acetate content expressed as % polyvinyl acetate

— — 0–2.5 0–2.5 0–2.5 0–2.5 0–2.5 0–2.5

Butyral content expressed as % polyvinyl butyral, approx.

— — 80 80 88 88 80 80

aSpecification properties

All properties were determined by ASTM methods except the following:

(1) Molecular weight was determined via size-exclusion chromatography with low-angle laser light scattering (SEC/LALLS) method of Cotts and Ouano in tetrahydrofuran.b

(2) Solution viscosity was determined in 15%-by-weight solutions in 60:40 toluene/ethanol at 25°C using a Brookfield Viscometer and in 10% solution in 95% ethanol @ 25°C using an Ostwald-Cannon-Fenske Viscometer.

(3) Ostwald solution viscosity for each product type measured with an Ostwald-Cannon-Fenske Viscometer. The solvents and solids levels used are as follows:

Product % solids Solvent Temperature (°C)

B-72 7.5 Anhydrous methanol

20

B-76, B-79 5.0 SD 29 ethyl alcohol

25

B-74, B-90, B-98

6.0 Anhydrous methanol

20

b P. Dublin, ed., Microdomains In Polymer Solutions (New York: Plenum Press, 1985), pp. 101-119.

4

Table 2. Chemical properties of Butvar® resins

Property Units ASTM method B-72 B-74 B-76 B-79 B-90 B-98

Resistance to

Weak acids — D543-56T E E E E E E

Strong acids — D543-56T E E E E E E

Weak bases — D543-56T E E E E E E

Strong bases — D543-56T E E E E E E

Organic solvents

Alcohols — D543-56T P P P P P P

Chlorinated — D543-56T G G F F G G

Aliphatic — D543-56T E E F F E E

Aromatic — D543-56T F F P P F F

Esters — D543-56T F F P P F F

Ketones — D543-56T F F P P F F

Key: E—excellent G—good F—fair P—poor

Table 3. Mechanical properties of Butvar® resins

Property Units ASTM method B-72 B-74 B-76 B-79 B-90 B-98

Tensile strength

Yield 103 psi D638-58T 6.8–7.8 6.8–7.8 5.8–6.8 5.8–6.8 6.3–7.3 6.3–7.3

Break 103 psi D638-58T 7.0–8.0 7.0–8.0 4.6–5.6 4.6–5.6 5.7–6.7 5.6–6.6

Elongation

Yield % D638-58T 8 8 8 8 8 8

Break % D638-58T 70 75 110 110 100 110

Modulus of elasticity (apparent)

105 psi D638-58T 3.3–3.4 3.3–3.4 2.8–2.9 2.8–2.9 3.0–3.1 3.1–3.2

Flexural strength, yield 103 psi D790-59T 12–13 12–13 10.5–11.5 10.5–11.5 11–12 11–12

Hardness, Rockwell

M — D785-51 115 115 100 100 115 110

E — D785-51 20 20 5 5 20 20

Impact strength Izod, notched ½ x ½ in.

ft-lb/in. D256-56 1.1 1.1 0.8 0.8 0.9 80

*Specification properties

5

Table 4. Thermal properties of Butvar® resins

Property Units ASTM method B-72 B-74 B-76 B-79 B-90 B-98

Flow temperature, 1,000 psi

°C D569-59 145–155 135–145 110–115 110–115 125–130 105–110

Glass transition temperature (Tg)

°C (1) 72–78 72–78 62–72 62–72 72–78 72–78

Ash content at 550°C

In nitrogen % (2) <3.0 <3.0 <2.0 <2.0 <3.0 <3.0

In air % (2) <1.0 <1.0 <0.75 <0.75 <0.75 <0.75

Heat distortion temperature

°C D648-56 56–60 56–60 50–54 50–54 52–56 45–55

Heat-sealing temperature °F (3) 220 220 200 200 205 200

(1) Glass transition temperature (Tg) was determined by differential scanning calorimeter (DSC) over a range of 30°– 100°C on dried granular resin.

(2) Ash content of the thermal gravimetric analysis (TGA) was determined as a weight loss versus temperature profile conducted at a heating rate of 10°C/min.

(3) Heat-sealing temperature was determined on a 1-mil dried film on paper cast from a 10% solution in 60:40 toluene/ ethanol. A dwell time of 1.5 sec at a 60-psi line pressure was used on the heat sealer.

Table 5. Electrical properties of Butvar® resins

Property Units ASTM method B-72 B-74 B-76 B-79 B-90 B-98

Dielectric constant

50 cP — D150-59T 3.2 3.2 2.7 2.7 3.2 3.3

10 cP — D150-59T 3.0 3.0 2.6 2.6 3.0 3.0

10 cP — D150-59T 2.8 2.8 2.6 2.6 2.8 2.8

10 cP — D150-59T 2.7 2.7 2.5 2.5 2.7 2.8

Dissipation factor

50 cP — D150-59T 0.0064 0.0064 0.0050 0.0050 0.0066 0.0064

10 cP — D150-59T 0.0062 0.0062 0.0039 0.0039 0.0059 0.0061

10 cP — D150-59T 0.027 0.027 0.013 0.013 0.022 0.023

10 cP — D150-59T 0.031 0.031 0.015 0.015 0.023 <0.24

Dielectric strength (1/8-in. thickness)

Short time V/mil D149-59 420 420 480 480 450 400

Step by step V/mil D149-59 400 400 390 390 370 380

6

Product types The properties of the various types of Butvar® resins are described in Tables 1 through 5. The resins are offered in a variety of molecular weight ranges and viscosities. B-76 and B-79 have lower hydroxyl content than the other Butvar resins. This permits broader solubility characteristics.

As a general rule, the substitution of butyral groups for acetate groups results in a more hydrophobic polymer with a higher heat distortion temperature. At the same time, the polymer’s toughness and adhesion to various substrates is considerably increased. The outstanding adhesion of the polyvinyl butyral resins is a result of their terpolymer constitution. Because each molecule presents the choice of three different functional groups to a surface, the probability of adhesion to a wide variety of substrates is increased substantially.

Although polyvinyl butyral resins normally are thermoplastic and soluble in a range of solvents, they may be cross-linked through heating and with a trace of mineral acid. Cross-linking is generally caused by transacetalization but also may involve more complex mechanisms, such as a reaction between acetate or hydroxyl groups on adjacent chains.

As a practical matter, cross-linking of the polyvinyl butyrals is carried out by reaction with various thermosetting resins, such as phenolics, epoxies, ureas, diisocyanates, and melamines. The availability of the functional hydroxyl groups in Butvar resins for condensations of this kind is an important consideration in many applications. Incorporation of even a small amount of Butvar resin into thermosetting compositions will markedly improve toughness, flexibility, and adhesion of the cured coating.

Polyvinyl butyral films are characterized by high resistance to aliphatic hydrocarbons and mineral, animal, and vegetable oils (with the exception of castor and blown oils). They withstand strong alkalis but are subject to some attack by strong acids. However, when employed as components of cured coatings, their stability to acids as well as solvents and other chemicals is improved greatly. Butvar will withstand heating up to 200˚F for prolonged periods with little discoloration.

Butvar: the right resin solutions Butvar resins generally are soluble in alcohols, glycol ethers, and certain mixtures of polar and nonpolar solvents. A representative list of Butvar solvents can be found in Table 6. In general, Butvar B-98 resin will show the same compatibility characteristics as B-90 and, therefore, should prove advantageous where physical and chemical properties of B-90 are desired but lower solution viscosities are necessary. The same is true for Butvar B-79 in relation to B-76.

When an alcohol is the only solvent, the viscosity of a Butvar solution increases as the molecular weight of the alcohol increases. Blends of alcohols with aromatic solvents provide the best starting point for the development of solvent systems. Where alcohols, such as ethyl or isopropyl, are employed either alone or in a mixture with other solvents, use the 95% grades. The presence of water gives lower solution viscosities than solutions utilizing anhydrous alcohols.

Butvar solutions show very marked viscosity increases as resin solids increase. This effect is shown in Graphs 3 through 10.

The lower hydroxyl content of Butvar B-76 and B-79 permits solubility in a wider variety of organic solvents as compared to the other grades of Butvar. One notable exception, however, is the insolubility of Butvar B-76 and B-79 in methanol. All other types of Butvar contain sufficient hydroxyl groups to allow for solubility in alcohol and in hydroxyl-containing solvents. The presence of both butyral and hydroxyl groups permits solution in mixtures of alcohol and aromatics.

Viscosities of Butvar resin solutions containing mixed solvents depend on the ratio of alcohol to aromatic. Viscosity curves for Butvar B-76, B-90, and B-98 in Graph 2 show minimum points in the general vicinity of 50% alcohol/50% aromatic.

7

Table 6. Solubility of Butvar® resins

SolventButvara

B-72, B-74Butvarb

B-76, B-79Butvarb

B-90, B-98

Acetic acid (glacial) S S S

Acetone I S SW

2-Butoxyethanol S S S

n-Butyl acetate I S PS

n-Butyl alcohol S S S

n-Butyl propionate I S I

Cyclohexanone S S S

Diacetone alcohol PS S S

Diisobutyl ketone I SW I

Dimethyl esters PSc S PSc

N,N-dimethylacetamide S S S

N,N-dimethylformamide S S S

Dimethyl sulfoxide S S S

Ethyl acetate, 85% S S S

Ethyl acetate, 99% I S PS

Ethyl alcohol, 95% or anhydrous S S S

Ethylene dichloride SW S SW

Isophorone PS S S

Isopropyl acetate I S I

Isopropyl alcohol, 95% or anhydrous S S S

Methyl acetate I S PS

Methyl alcohol S SW S

Methyl amyl ketone SW S PS

Methyl ethyl ketone PS S PSc

Methyl isoamyl ketone I S SW

Methyl isobutyl ketone I S I

Methyl propyl ketone SWc S SWc

Methylene chloride PS S S

N-methyl-2-pyrrolidone S S S

Naphtha (light solvent) I SW I

Propyl propionate I S I

Propylene dichloride S S S

Tetrachloroethylene SW SW SW

Tetrahydrofuran S S S

Toluene SW SW SW

Toluene/ethyl alcohol, 95% (60:40 by weight) S S S

1,1,1-trichloroethane SW S SW

Xylene I PS SWa5% solids solution agitated for 24 hours at room temperature b10% solids solution agitated for 24 hours at room temperature cClear solution at 50°–80°C

Key: S—soluble PS—partially soluble I—insoluble SW—swells

8

A common solvent for all of the Butvar® resins is a combination of 60 parts toluene and 40 parts ethanol (95%) by weight. The viscosities of all the Butvar resins in this solvent blend are shown in Graphs 2 and 3. The viscosities of Butvar resins in alcohols are shown in Graphs 4 through 8. Graphs 9 and 10 present the viscosities of Butvar resins in 2-butoxyethanol.

For compositions of Butvar, methyl alcohol will tend to give the lowest viscosity and will therefore permit the use of higher solids when used as a component of a solvent blend. When much more than 10% to 15% alcohol is used in a formulation for spray application, blushing may result.

The solvent blends in Table 7 are suggested for all Butvar grades. They are useful as starting points in the development of solvent blends for the other types.

Selection of a suitable solvent system involves a number of factors. End use and application technique used will necessitate consideration of solution viscosity, cobweb formation, blushing, evaporation, solvent release, and toxicity characteristics. In most cases, the choice of components of solvent blend will involve compromises in at least some of these factors so that a desired combination of properties may be obtained.

Aliphatic hydrocarbons can be tolerated in only very small proportions. Aromatic hydrocarbons, alcohols, esters, ketones, and halocarbons, when not active solvents, are generally satisfactory as diluents or latent solvents. Solvent blends are more likely to be successful when their mean solubility parameter and hydrogen bonding fall within the ranges shown in Graph 1 and Table 8.

Butvar resins can be dissolved quite rapidly using conventional techniques. To ensure thorough and uniform wetting of all particles, it is important to add the resin slowly to the solvent system with adequate stirring. With some mixed solvents, it may be desirable to slurry the resin in the hydrocarbon or other nonsolvent component and add the more active solvent components to the slurry under adequate agitation.

Table 7. Suggested solvent blends for Butvar® resins

A B C D

Diacetone alcohol 22.5 20.0 15.0 —

n-Butyl alcohol 22.5 20.0 15.0 —

Ethyl alcohol, 95% 10.0 20.0 20.0 55.0

Xylene 45.0 40.0 30.0 —

Toluene — — 20.0 45.0

Total 100.0 100.0 100.0 100.0

Relative viscosity High Medium Low Low

Relative evaporation rate Slow Medium Medium Very fast

Application technique Spray Dip, roll Dip, roll Brush

Drying technique Bake Bake Bake Air dry

9

Graph 1. Hansen solubility parameters of Butvar® resinsa

Polyvinyl butyral Hansen solubility parameters

Dispersive δD (MPa1/2)

Polar δP (MPa1/2)

H-bonding δH (MPa1/2)

Sphere radius(MPa1/2)

l B-90 and B-98 21.72 7.85 14.55 15.0

l B-72 and B-74 21.19 8.70 14.02 13.7

l B-76 and B-79 17.72 7.18 12.62 9.7aHSPiP Software, Version 4.0.08, 2013

In general, solvents or solvent mixtures having δD, δP, and δH coordinates within a polymer sphere, RED ≤1, are solvents; those outside a sphere are nonsolvents. Relative energy difference (RED) = [4(δD2 – δD1)2 + (δP2 – δP1)2 + (δH2 – δH1)2]½/sphere radius.

Table 8. Hansen solubility parameters for common solvents and solvent mixturesa

Solvent Solvent ratio (wt%)Dispersive δD (MPa1/2)

Polar δP (MPa1/2)

H-bonding δH (MPa1/2)

Acetone 100 15.5 10.4 7.0

2-Butoxyethanol 100 16.0 5.1 12.3

n-Butyl acetate 100 15.8 3.7 6.3

Diisobutyl ketone 100 16.0 3.7 4.1

N,N-dimethylacetamide 100 16.8 11.5 9.4

N,N-dimethylacetamide/xylene 60/40 17.2 7.2 7.3

Dimethyl sulfoxide 100 18.4 16.4 10.2

Dioxane 100 17.5 1.8 9.0

Dioxane/tetrahydrofuran 50/50 17.1 3.9 8.5

Ethanol 100 15.8 8.8 19.4

Ethanol/water 95/5 15.8 8.2 20.5

Ethyl acetate/ethyl alcohol 99/1 15.8 5.3 7.3

Ethylene dichloride 100 18.0 7.4 4.1

Ethylene glycol 100 17.0 11.0 26.0

Isopropanol 100 15.8 6.1 16.4

Isopropanol/water 98/2 15.8 6.3 16.8

Methanol 100 14.7 12.3 22.3

Methyl amyl ketone 100 16.2 5.7 4.1

Methylene dichloride 100 17.0 7.3 7.1

Methyl isobutyl ketone 100 15.3 6.1 4.1

Propylene glycol monomethyl ether 100 15.6 6.3 11.6

Propylene glycol monomethyl ether acetate 100 15.6 5.6 9.8

Tetrahydrofuran 100 16.8 5.7 8.0

Toluene 100 18.0 1.4 2.0

Toluene/ethanol 50/50 16.9 5.2 11.0

Trichloroethane 100 16.8 4.3 2.0

Xylene 100 17.8 1.0 3.1

Xylene/N,N-dimethylacetamide 50/50 17.2 6.1 6.6aCharles M. Hansen, Hansen Solubility Parameters: A User’s Handbook, 2nd Edition, CRC Press (2007)

D H

P

30

24

18

12

6

30

24

18

12

6

6

27

24

2118

15

12

18

24

30

10

Graph 2. Viscosities of Butvar in toluene/ethanol (95%) (15% solids)

Graph 3. Viscosities of Butvar in 60/40 toluene/ethanol (95%) (by weight)

1,800

1,600

1,400

1,200

1,000

800

600

400

200

00 20 40 60 80

Toluene

100 80 60 40 20

Ethanol

Solvent composition by weight

Broo

kfie

ld V

isco

sity

at

25ºC

, cP

— B-76

— B-90

— B-98

100,000

10,000

1,000

100

10

10 5 10 15 20 25 30

Broo

kfie

ld V

isco

sity

at

25ºC

, cP

% total solids

— B-72

— B-76

— B-79

— B-90

— B-98

11

Graph 4. Viscosities of Butvar in methanol

Graph 5. Butvar in ethanol (95%)

Graph 6. Butvar in ethanol (95%)

100,000

10,000

1,000

100

10

10 5 10 15 20 25 30

Broo

kfie

ld V

isco

sity

at

25ºC

, cP

% total solids

— B-72

— B-90

— B-98

100,000

10,000

1,000

100

100 5 10 15

Broo

kfie

ld V

isco

sity

at

25ºC

, cP

% total solids

— B-72

— B-74

100,000

1,000

100

100 5 10 15

Broo

kfie

ld V

isco

sity

at

25ºC

, cP

% total solids

— B-76

— B-79

— B-90

— B-98

12

Graph 7. Butvar in n-butanol

Graph 8. Butvar in n-butanol

Graph 9. Butvar in 2-butoxyethanol

Graph 10. Butvar in 2-butoxyethanol

100,000

10,000

1,000

100

100 5 10 15

Broo

kfie

ld V

isco

sity

at

25ºC

, cP

% total solids

— B-72

— B-74

10,000

1,000

100

100 5 10 15

Broo

kfie

ld V

isco

sity

at

25ºC

, cP

% total solids

— B-76

— B-79

— B-90

— B-98

10,000

1,000

100

100 5 10 15

Broo

kfie

ld V

isco

sity

at

25ºC

, cP

% total solids

— B-76

— B-79

— B-98

100,000

10,000

100

1,000

100 5 10 15

Broo

kfie

ld V

isco

sity

at

25ºC

, cP

% total solids

— B-72

— B-74

— B-90

13

Compatibility The compatibility of Butvar® polyvinyl butyral resins with plasticizers, modifiers, and other various resins is well established. Butvar readily lends itself to compounding with other additives to enhance its physical and chemical properties. Plasticizers are often used to impart improved flexibility over a broader temperature range. See Table 9.

Table 9. Plasticizers for Butvar® resin

Type Name or trademarkKnown Butvar/plasticizer

compatibility level

Hexanoate Eastman TEG-EH (triethylene glycol di-2-ethylhexanoate) 1:1

Adipate Santicizer® 97 (dialkyl adipate) 4:1

Santicizer 367 (dihexyl adipate) 3:1

Dioctyl adipate (DOA) 4:1

Blown linseed oil Linseed oil —

Citrate Tributyl citrate —

Phosphate Santicizer 141 (2-ethylhexyl diphenyl phosphate) 1:1

Santicizer 148 (isodecyl diphenyl phosphate) 1:1

Santicizer 154 (tert-butylphenyl diphenyl phosphate) 1:1

Santicizer 143 (triaryl phosphate ester blend) 1:1

Tricresyl phosphate (TCP) 1:1

Triphenyl phosphate (TPP) 2:1

Phthalate Santicizer 261 (alkyl benzyl phthalate) 2:1

Santicizer 278 (alkyl benzyl phthalate) 4:3

Santicizer 160 (butyl benzyl phthalate) 1:1

Dibutyl phthalate (DBP) 1:1

Dialkyl phthalate 4:1

Dioctyl phthalate (DOP) 4:1

PE glycol ether Pycal™ 94 —

Polyester Paraplex™ RGA-8 —

Process castor oil #15, #30, #40 2:1

Raw castor oil #1 Castor 1:1

Ricinoleate Flexricin™ P-3 (butyl ricinoleate) 2:1

Rosin derivatives Hercolyn™ —

Sebacate Dibutyl sebacate —

Sulfonamide Ketjenflex™ 8 (n-ethyl toluenesulfonamide) 1:1

Ketjenflex™ 9S (toluenesulfonamide) 2:1

The values given in this table are a guide to the compatibility limits of the plasticizers in the various resins shown. (If no value is given, the limit is unknown.) The highest concentration tested was 100 phr. Where the value is given as 1:1, some plasticizer/resin combinations may have even greater compatibility. However, since the values given apply to a resin type, the compatibility with a particular commercial grade should be checked when evaluating a specific compound, particularly if the plasticizer content of the formulation is to be near the ceiling value indicated.

14

Cross-linkers such as Santolink® phenolic and Resimene® amino resins are used to impart greater toughness and thermal resistance. Table 10 depicts the compatibility of Butvar® polyvinyl butyral resins with other modifiers and resins.

Table 10. Compatibility of Butvar with various resinsa

SolventButvar

B-76, B-79Butvar B-72, B-74,

B-90, B-98

Acrylate — I I

Alkyd Beckosol™ 11-035 P P

Duraplex™ 11-804 P P

Cellulose Cellulose acetate I I

Cellulose acetate butyrate P P

Ethyl cellulose P P

Nitrocellulose, RS™ C C

Nitrocellulose, SS™ C C

Chlorinated rubber — I I

Coumarone-indene — I I

Epoxy EPI-REZ™ 540-C C C

EPON™ 1001F, 1007F C C

Araldite™ 6069 C C

Fossil Damar C C

Isocyanate Desmodur™ AP Stabil C C

Melamine formaldehyde Resimene® 717 and 881 P P

Resimene® 730 and 741 P P

Phenolic OxyChem™ 02620, 92600, 29107 C C

Durite™ P-97 C C

Methylon™ 75-108 C C

Santolink® EP-560 (butyletherified) C C

SP-1044 resin C C

Rosin derivatives Pentalyn™ H P P

Staybelite-E™ hydrogenated rosins C P

Vinsol™ C C

Shellac — C C

Silicone DC 840 C P

DCZ 6018 C P

Sulfonamide Ketjenflex™ MH P P

Urea formaldehyde Resimene® 918 P P

Vinyl chloride copolymer VAGH, VAGD P IaRefers to film compatibility provided mutual solvents are used

Key: C—compatible in all proportions P—partially compatible I—incompatible

15

Insolubilizing reactionsMany applications for vinyl acetal resins involve curing with a thermosetting resin to obtain the balance of properties desired. The free hydroxyl groups in vinyl acetal resins present a point of chemical reactivity through which the resins may be insolubilized. In general, any chemical reagent or resinous material which reacts with secondary alcohols will react with the polyvinyl butyral to inhibit solubility.

The properties of coatings vary greatly with the type and amount of cross-linking agent used.

OH

OHOH

CH3

Butvar

Butvar

Butvar

Butvar

Phenolic

H+

(R)HOH2 CC H 2OH

OH

CH3

O

O OH

CH3

(R)H2 CC H2

OH

CH3

OH

Butvar

Epoxy

Butvar

CH2 CH

CH CH2

CHOC

CH3

CH3

CH3 OH

CH3

CCH2 CH2O O CH2 CH2OCH2 CH

OH

CH

O O

C

O

O

O

O

C

X

C

O

O

CH2

C

O

O

Typical epoxy resin

Reaction with phenolics

Reaction with epoxies (anhydride cure)

16

Reaction with dialdehydes

Reaction with melamines

Reaction with isocyanates

CH CH2 CH

OH OH

O

O

OH OH

HC H+

CH

CH CH2 CH

O O

CH CH2 CH

HC

CH

OO

CH CH2 CH

Butvar

Butvar

O

N N

O

HO

OH

Butvar

Butvar

Butvar

Butvar

Melamineresin

HOH2C

NH 2

CH2OHNH NHNH HN(R)C CC C

N

C

N N

NH2

C

N

N N

H2C

NH2

CH2NH NHNH HN(R)C CC C

N

C

N N

NH2

C

N

H+

O

OH

R

NCO

OH

NCO

O

NH

C

C O

O

R

NH

Butvar

Diisocyanate

Butvar

Butvar

Butvar

Tertiary amine

17

ApplicationsWire enamelsButvar® resins may be used to overcoat magnet wire so that coils made from that wire can be cemented with heat or by solvent activation.

Coiled or shaped magnet wire with a polyvinyl butyral overcoat is tough and flexible. The presence of hydroxyl groups in the polyvinyl butyral molecule permits the polyvinyl butyral not only to cross-link with itself but also to cross-cure with phenolic or isocyanate resin.

The overall balance of physical and chemical properties has made this type of overcoat based on Butvar a leader in the field for many years.

Surface coatingsButvar vinyl acetal resin may be used alone or in combination with a wide variety of resins to give functional surface coating compositions. Films which may be air dried, baked, or cured at room temperature are obtained by proper compounding. The presence of hydroxyl groups in the polymer molecule not only enables good wetting of most substrates but also furnishes a reactive site for chemical combination with thermosetting resins.

Wash primers In protective coatings for metal, the best-known vinyl acetal application is in wash primers, also referred to as metal conditioners. Compared with other corrosion-inhibiting materials, wash primers are unique and more effective because they offer, in a single treatment, several means of preventing corrosion. These anticorrosive primers apply easier, adhere better, and dry faster than more conventional materials.

The action of wash primers over steel, for example, is as follows:

• First, an iron oxide and zinc phosphate film similar to that formed in the common phosphating processes is deposited on the metal.

• Second, the wash primers provide a continuous supply of chromate ions to repair pinholes in the phosphate film, eliminating the need for a special chromate rinse.

• Third, the polyvinyl butyral film is chemically bound in the inorganic layers through a chromium complex, providing additional mechanical protection to the metal surface.

In effect, this type of primer actually phosphatizes the metal at the surface, supplies a corrosion-inhibiting pigment in a tenaciously adhering binder, and dries to take most topcoats.

Wash primers are widely used on a variety of metal structures, such as storage tanks, ships, and airplanes. Highway departments also have shown a keen interest in these coatings for bridges, dam locks and, in particular, highway guardrails. In finishing trucks or house trailers fabricated of phosphated or galvanized steel or aluminum, wash primers provide corrosion resistance and adhesion under single-coat styrenated alkyd and other modified alkyd enamels. On metal that is subject to immersion and corrosion conditions, wash primers are specified under urethane and vinyl topcoats.

Military-specification wash primersThe U.S. Navy Bureau of Ships has long recognized the need for the use of the wash primer as a surface pretreatment for metals prior to subsequent painting. Military Specification DOD-P-15328D entitled Primer, Pretreatment is required to be used on all metal surfaces. This primer is a two-package system containing Butvar B-90 in a solvent system consisting of normal butanol and either ethanol or isopropanol. By comparison, the Department of the Air Force and the U.S. Navy Bureau of Naval Weapons have approved a slightly different pretreatment formulation designated Coating Compound, Metal Pretreatment, Resin-Acid MIL-C-8514C (ASG). This system specifies the use of either Butvar B-76 or Butvar B-90 in a solvent system consisting of butanol and ethanol. Specific details of both wash primer systems can be found in the particular specification involved.

18

Nonspecification wash primers: B-1030 with ButvarWash primer B-1030 formulation is a two-package system based on Butvar B-76 resin and a thermosetting phenolic resin. This formulation was designed to give higher early water resistance than the well-known military-specification wash primers. Coatings based on formulation B-1030 exhibit reduced tendency to blister and lose adhesion in high humidity. The B-1030 formulation also has nonsettling characteristics. In contrast to the older wash primer formulations, B-1030 does not display hard pigment settling of the base grind.

The thermosetting resin content of the B-1030 formulation not only increases water resistance but also contributes to reduced solvent sensitivity. Thus, good adhesion and corrosion resistance are retained under alkyd, alkyd-nitrocellulose, acrylic, and vinyl topcoats and also under epoxy, urethane, polyvinyl acetate, and alkyd melamine topcoats.

Table 11. Wash primer B-1030 with Butvar A. Base grind % by weight

1. To a solution of: Butvar B-76 1.24

Ethanol, 95% 9.35

Methyl ethyl ketone 9.97

2. Add: Basic zinc chromate pigment 11.52

Celite™ 266 4.82

3. Grind to Hegman fineness of 6, N.S. scale.

4. Add solution of: Butvar B-76 7.39

Ethanol, 95% 23.08

Methyl ethyl ketone 24.63

Santolink® EP-560 8.00

Total 100.00

5. Grind for 30 minutes and package.

B. Reducer % by weight

Phosphoric acid, 85% 7.50

n-Butanol 92.50

Total 100.00

Mix for several minutes and package

Reduced primer properties (Pigment grind to reducer; 1:1 by volume)

NVM 19%

Weight per gallon 7.5 lb

Coverage 533 sq ft/gal at 0.3 mils dry

Pot life 8–12 hours

Single-package wash primer: B-1011 with ButvarWash primer B-1011 is a clear, green single-package primer also known as a reacted wash primer. Based on Butvar B-90 resin, it has excellent stability in both concentrated and diluted forms and air dries to clear glossy films of very low color. Films of the primer possess good adhesion to steel, phosphated steel, galvanized steel, brass, copper, wood, stainless steel, and chrome plate. Although designed to enhance adhesion, this coating also functions as a corrosion-inhibiting primer for a variety of topcoats but, in many cases, may afford protection as the sole coating.

19

Chromate-free wash primers with Butvar Traditional wash primer formulations have generally employed zinc chromate as the anticorrosive pigment. Due to toxicity concerns associated with chromates, alternative anticorrosive pigments, such as zinc molybdate,

borate, or borophosphate, are suggested. Substitution of these pigments for zinc chromate on an equal weight or volume basis are suggested starting points for reformulation. A chromate-free wash primer based on U.S. government specification DOD-P-15328D is shown in Table 13.

Table 12. Wash primer B-1011 with ButvarMaterial % by weight

A. Acetone 44.40

Anhydrous ethanol 36.30

Butvar B-90 11.00

B. 85% phosphoric acid (USP) 0.72

Water 6.48

C. Chromic acid (99+%) 0.37

Water 0.73

Total 100.00

Properties

NVM 12%

Viscosity 21 sec, No. 4 Ford cup

lb/gal 7.0

Coverage 384 sq ft/gal at 0.3 mils dry

Table 13. Sherwin-Williams chromate-free wash primer

A. Base grind DOD-P-15328DMoly-White™

X92Butvar**

B-90, B-98

lb lb gal

Butvar B-90 56.0 56.0 6.10

n-Butanol 125.0 125.0 18.48

Isopropanol, 99% 353.0 353.0 53.80

Moly-White X92 — 39.7 1.70

Basic zinc chromate 54.0 1.70

Magnesium silicate, MP40-27 8.0 8.0 0.34

Furnace black 0.6 0.6 0.34

Water, DI 15.0 15.0 1.80

— — 82.26

B. Reducer

Phosphoric acid, 85% 28.0 28.0 2.0

Water, DI 25.0 25.0 3.0

Isopropanol, 99% 99.0 99.0 15.0

— — 20.0

Alternative chromate-free pigments include PhosGuard® J-0800 from Mineral Pigments Corporation and Borogard® ZB from U.S. Borax.

20

Metal coatingsButvar® resins are used in a wide variety of metal coating applications in combination with other resin types, such as phenolics, epoxies, isocyanates, melamines, ureas, etc. When used with these various modifying resins, Butvar can improve coating uniformity, minimize cratering, improve adhesion, and increase coating toughness and flexibility.These resin combinations can be compounded to produce baked coatings with good chemical resistance which also will withstand postforming. Applications of such coatings can be made by conventional methods, including brush, spray, dip, and fluidized bed. End-use applications include drum and can linings as well as the wide variety of metallic substrates, which are coated by the fluidized bed technique. Curable coatings containing Butvar resin may be formulated to meet the extractability requirements of the U.S. Food and Drug Administration for indirect food additive uses.

Metal coating 2009 is one example of the use of Butvar in combination with other resins—in this case, phenolic and epoxy—to produce an excellent coating. This particular combination provides excellent abrasion resistance, toughness, flexibility, adhesion, and chemical resistance. Specific application tests have shown that this system should make outstanding can or drum linings.

Table 14. Metal coating 2009 Material % by weight

Diacetone alcohol 17.4

n-Butanol 17.4

Ethanol, 95% 7.7

Xylol 34.7

Santolink® EP-560 5.1

EPON™ 1007F 13.0

Butvar® B-90 2.0

10% phosphoric acid (in above solvents)

2.7

Total 100.0

Properties

NVM 20%Application: Spray or roller

Cure cycle sequence: Room temperature. Dry 15 minutes, followed by 30 minutes at 190˚F and 20 minutes at 400˚F.

21

Wood finishes Protective wash coats and sealers

Butvar® resin is widely used as a component of wash coats and sealers in wood-finishing operations. It provides good holdout, intercoat adhesion, moisture resistance, flexibility, toughness, and impact resistance to the coating system. In addition, the wood substrate is protected against discoloration when Butvar is used in the finish. Combinations involving nitrocellulose, shellac, and shellac ester along with other resin types are used with Butvar under many common topcoats (Table 15). Butvar is particularly effective for improving the holdout of polyester and polyurethane coatings as well as protecting the wood substrate against color changes caused by light.

The following starting formulation is representative of the kind of wood sealer or wash coat that can be compounded from Butvar.

Table 15. Sealer/wash coat with Butvar Material % by weight

Butvar B-98 6.1

Nitrocellulose, RS™, ¼ second 9.2

Butyl acetate 32.9

Ethanol, anhydrous 5.5

Isopropanol, 99% 10.9

Methyl isobutyl ketone 8.8

Xylol 13.3

Toluol 13.3

Total 100.0

Properties

NVM 12.5%

Viscosity20 sec,

No. 4 Ford cup

Knot sealers

The polyvinyl butyral resins are excellent barriers to bleeding of terpenaceous matter from knots, heartwood, and rosin ducts. The Western Pine Association has developed a superior knot sealer based on Butvar. The system consists of a combination of Butvar and phenolic resins (Table 16).

Table 16. Western Pine Association knot sealer, WP578 Material % by weight

Butvar B-90 3.3

Durite™ P-97 40.0

Ethanol, 95% 56.7

Total 100.0

Properties

NVM 23.3%

Application: Brush

The preceding formulation is designed for brush application. However, it has been adapted to application from an aerosol spray can, giving the same outstanding performance as the brush-applied system.

22

Adhesives Structural adhesives

Structural adhesives were originally developed for use in‚ the aircraft industry to replace rivets and other methods of joining and fastening. Refinements in formulating structural adhesives led to their use in bonding brake linings, in the electrical and electronic industries on printed circuits, in structural composite-fiber binders for aerospace or antiballistic applications, and in the architectural field for the manufacture of interior and exterior curtain walls.

Combinations of Butvar® resin with thermosetting resins have long been used in bonding aircraft components— in fact, the system was the first synthetic resin adhesive to be used for bonding metals in structural applications.

Phenolic resins

In some structural adhesive formulations, Butvar resins are combined with alkaline-catalyzed phenolic laminating resins, such as Durite™ LS-433 or Plyophen™ 22-023. Compared with other general types of structural adhesive systems (epoxy-phenolic and synthetic rubber-phenolic), the PVB-phenolic gives the highest shear strength values at temperatures up to 250°F. Other outstanding properties of the PVB-phenolic system include high peel strength at very low temperatures, excellent dielectric properties, and exceptionally good creep resistance as measured by the ability of the bond to carry sustained loads for extended periods of time.

Polyvinyl butyral-phenolic ratios from 10:1 to 10:20 have been used successfully for structural adhesives, although 10:5 seems to be the best ratio for a compromise of properties. As the amount of phenolic is reduced, the cured adhesive becomes more flexible and, in most cases, peel strength increases. In addition, because of the increased thermoplastic nature of the system, the high-temperature shear strength is reduced. These effects, i.e., increased peel and reduced high-temperature shear strength, occur when the cure time is shortened or the cure temperature is lowered.

Structural adhesives based on polyvinyl butyral resins can be applied as a solution, an unsupported film, a supported film on paper or cloth, or a mixture of liquid and solid.1

In a solution adhesive system, the choice of solvents is important both for viscosity control of the solution and proper drying and filming characteristics. Proper drying of the adhesive film is very important, as only a small amount of residual solvent can greatly affect the various final properties. Yet the solvent cannot be so volatile that blushing occurs. Sprayed films are much more sensitive to blushing than brushed or roller-coated films. For brushing, solvents in the boiling range of 75° to 100°C are advised because they can be removed by air drying and then force drying for 30 to 60 minutes at 105°C. Solutions for spraying can tolerate small amounts of higher-boiling solvents, such as xylene and butanol.

Viscosity of the adhesive solution affects the smoothness and the thickness of the final brushed or sprayed film. For brushing, the proper viscosity is obtained at the following solids content (with a 10:5 PVB/phenolic ratio): Butvar B-90, 21%; Butvar B-72, 16% to 18%. For spraying, the solids content should be reduced to obtain nonblushing, noncobwebbing films.

Epoxies and other thermosetting resins

Butvar resins are compatible with many epoxy resins and can confer such improvements on epoxy-based systems as increased impact resistance and peel strength. In epoxy systems, as in phenolic systems, the vinyl acetal resins can serve as both coreactant and flexibilizer.

The addition of small amounts of compatible plasticizer to an adhesive system combining a vinyl acetal resin with a thermosetting resin increases the flexibility and impact resistance of the bond with only slight sacrifice in high-temperature shear. This increased flexibility is most evident when peeling thick adherends and at high peeling speeds.The tack or heat-seal temperature of the uncured adhesive is also appreciably lowered by the addition of plasticizer. Adhesives with pressure-sensitive properties in the uncured state can be developed which, when cured, will have temperature shear bond strength of more than 1,000 psi.

1See U.S. Patent 2,499,134.

23

High-strength bonding procedure

For high-strength bonds, substrate cleaning is very important. Usually the removal of surface contamination, such as oil film, dust, etc., is sufficient. Such cleaning normally is achieved by solvent or by detergent wash. However, for highest-strength bonds, chemical surface preparation is employed. The following metals require the preparation noted:

• Aluminum alloys—acid oxidation

• Copper—alkaline oxidation

• Steel—a pickling bath to remove oxide scale

Care should be taken to avoid touching the cleaned panels or exposing them to any contaminated atmosphere. The adhesive should be applied to the cleaned surface as soon as possible.

A dry glue line of 3 to 10 mils has been found quite satisfactory. With solvent systems, this thickness usually can be achieved with 2 to 4 brushed coats of adhesive on each adherend. With very thin glue lines, even pressure must be applied to the laminate during cure so that consistent bonds are obtained. Thicker glue lines have greater flow and absorb unequal curing pressures.

Performance characteristics

The quality of a structural bond for a particular application is usually described in terms of its shear strength, peel strength, creep properties, fatigue strength, and environmental resistance. In aircraft applications, high-temperature shear, fatigue resistance, creep, and oil and gas resistance are most important. In printed circuits, peel strength, blister resistance, and dielectric properties are of primary importance. For architectural use, high peel strength and long-term resistance to dead load and extremes of atmospheric environment are the outstanding requirements.Adhesives based on Butvar® resins excel in all of these characteristics.

The requirements and methods for testing adhesives for aircraft applications are presented in Military Specifications MM-A-132 and MIL-A-25463-30. Test methods for architectural and printed circuit applications are contained in various ASTM and NEMA specifications.

Adhesive strengths

Typical test values for phenolic bonds of Butvar resins measured by these techniques are in Table 17.

Table 17. Adhesive strengths

Amount of psi shear strength at Peel at 72°FVinyl acetal phenolic, phra Cure 72°F 180°F 250°F 300°F lb/in. width

Butvar B-72 50 30 min, 330°F 6,000 4,000 1,400 500 25–30

Butvar B-90 50 30 min, 330°F 5,700 2,800 1,000 — 30–35

Butvar B-72 100 20 min, 300°F 5,000 3,300 1,100 — 35–40

aphr = parts per hundred resin

Test procedures: Shear—aluminum to aluminum as per MIL-A-8431 Peel—6-mil aluminum to 64-mil aluminum peeled at 5 inches per minute

24

Hot-melt adhesives

Butvar® resin makes an excellent base for hot-melt adhesives even where difficult-to-bond surfaces are involved. The many types of Butvar resins allow the best match to individual applications. For example, Butvar B-98 can be formulated to produce a hot melt with low-viscosity characteristics. B-72 can be used to produce an adhesive with similar chemical properties but higher viscosity. Other types, such as B-76, are available to produce adhesives where less cross-linking is desirable.

Table 18 shows a starting formulation for a hot melt based on Butvar.

Table 18. Typical hot-melt formulation Material Parts by weight

Butvar B-76 10

Santicizer® 160 10

Castorwax™ 35

Poly-Pale™ rosin resin 26

Staybelite-E™ hydrogenated rosin 19

Total 100

Textile coatings One of the unique uses of Butvar polyvinyl butyral resin is in the textile coating field. It can be compounded to make fabrics water and stain resistant without noticeably affecting the appearance, feel, drape, and color of the fabric. Tablecloths, drapes, slipcovers, shower curtains, aprons, smocks, and children’s bibs are some of the more common items which can be prepared. Outside the home, fabrics coated with Butvar serve as rainwear, porch furniture upholstering, awnings, and beach accessories.

Butvar, which provides a transparent film, can be applied to practically all common fabrics. Cotton, wool, silk, nylon, viscose rayon, and other synthetics can be successfully coated. As a rule, almost any fairly tight woven fabric with a flat surface can be made water and stain resistant with a coating based on Butvar.

Advantages as textile coating The advantages of Butvar as a textile coating resin stem from the following properties:

• Transparency: Butvar can be made into a clear, colorless coating with excellent light resistance and aging characteristics.

• Adhesion: After curing, Butvar adheres readily to practically all fabrics, including those normally considered difficult to coat, such as nylon, viscose rayon, and fiberglass.

• Hand and appearance: A coating with Butvar has the soft, warm, flexible feel of an uncoated fabric yet possesses all the functional characteristics of coated fabrics.

• Functional properties: Butvar combines these attributes with functional properties comparable to those of the best textile coating materials in the field. During the drying and curing operations, Butvar is transformed into an elastomer which becomes a permanent part of the fabric.

Fabrics coated with properly compounded and cured Butvar have outstanding softness and flexibility without tackiness of low softening temperatures. They have excellent chemical and water resistance. Films of Butvar resin are tough and will resist abrasion and wear. Coatings can be applied from high-solids solutions made with common solvents. Clear coatings with Butvar may be applied from solutions of up to 35% solids; pigmented coatings may be as high as 45% solids.

Solutions of Butvar are ideally suited to coating with either rubber or pyroxylin spreaders. Solids content can be high and the solvents fast evaporating. The material will flow well after being spread. For most applications, a light coating averaging 1½-oz dry to the square yard is recommended. The solution of Butvar, which can be prepared in a solvent mixture of alcohol and naphtha, is applied in generally two to five passes, depending on the type of fabric and the coating operation. This is followed by a flat topcoat to remove gloss and tack normally associated with coated fabrics. Usually two topcoats are required for a smooth, skip-free coating.

The first two coats should be low in viscosity for proper penetration of the coating into the fiber interstices. The relationship between depth of penetration and coating viscosity will necessarily depend on the fabric construction and must be determined on the basis of trials. If an excessively high coating viscosity is used for the initial coats, peel adhesion, Mullen, and other physical test properties will suffer. Experience has shown that superior coatings are produced by many thin coats rather than by a few heavy applications.

25

Butvar is unique among vinyl resins in its ability to be cured in a manner somewhat analogous to rubber. Curing improves both heat and solvent resistance and adhesion to the fabric. Curing Butvar is accomplished by incorporating cross-linking resins, such as urea, phenolics, melamines, and isocyanates. Since the reaction involves the hydroxyl groups on the chain of Butvar, only a small amount of a modifying resin is needed to substantially increase the heat and solvent resistance of the Butvar resin.

A formulation incorporating such a cross-linking resin is shown in Table 19.

Table 19. Typical textile coating formulation Material Parts by weight

Butvar B-72 48.0

Tricresyl phosphate 48.0

Ethanol 95% 84.2

Toluene 64.8

Water 8.0

Resimene® AQ-7550 3.5

p-Toluene sulfonic acid 0.7

p-Nonylphenol 0.2

Compounding

1. Combine solvents and plasticizer.

2. Add Butvar B-72 with stirring; heat if desired to speed solution.

3. Cool batch, blend in p-nonylphenol, Resimene AQ-7550, and p-toluene sulfonic acid in that order.

Compound properties

% solids 39

Viscosity (freshly made), cP ca 70,000

Viscosity (24 hours), cP ca 75,000Cure cycle sequence: Room temperature. Drying 15 minutes, followed by 30 minutes at 190˚F and 20 minutes at 400˚F. Appli-cation: Spray or roller

Coated stocks are cured after all coats have been applied. Premature curing of any coat due to overheating will reduce the adhesion of subsequent coats. The time required for curing will depend on the resins, the catalysts employed, and the temperature of the curing oven. Cure time will vary from approximately 1 hour at 250°F to 5 minutes or less at 350°F.

Coatings with Butvar have been cured satisfactorily in festoon dryers at 200°F, steam-heated ovens at 300°F, gas ovens, and even dryer cans. In all cases, overheating should be avoided to prevent loss of plasticizer and stiffening.

A properly coated and cured fabric will be water resistant; will be resistant to ink stains, coffee, tea, cooking oils, and fats; and will have excellent washability. Most soilings can be wiped away with a damp cloth. Should the uncoated side require laundering, neutral soap and warm water should be used. The coated fabric can be ironed on the uncoated side.

Coatings based on Butvar cannot be dry cleaned. Such treatment will remove the plasticizer and leave a stiff, harsh coating which will break on flexing.

Ceramic binder applicationsButvar polyvinyl butyral resins are recognized as the binder of choice in the processing of ceramic tape cast materials. The resin imparts excellent green strength and flexibility to the ceramic tape. It is compatible with many common solvents and plasticizers and burns out cleanly during sintering.

Butvar resin is also used as a binder medium in thick film processing. Butvar is formulated in the solvent vehicle used to deposit the circuit pattern on the ceramic surface. The primary advantages of using Butvar resins are their solubility in a wide range of solvents and uniform adhesion to conductive metals.

26

Tape castingButvar is regarded as the binder of choice for the ceramic tape casting process due to the following benefits:

• Butvar resins provide excellent green strength to the unified tape. - Butvar allows multiple tapes to be laminated in

the green stage. - Low Butvar concentrations allow for higher-density

substrates after firing.

• Butvar is soluble in many volatile yet inexpensive solvents.

- Flexibility in choosing Butvar product types and load levels for a wide range in binder solution viscosities and, therefore, ceramic slip viscosities.

• Butvar is compatible with many of the plasticizers used in ceramic systems. - Choose from dialkyl phthalates, benzyl phthalates,

adipates, or phosphates commonly used.

• Butvar burns out cleanly with a minimum of warpage to the fired part. - The product shrinks uniformly. - Low gel content minimizes surface defects.

• Butvar has natural dispersing properties and is compatible with common dispersing agents, such as fish oils or phosphate esters.

The medium- to low-molecular-weight resins, Butvar B-76, B-79, B-90, or B-98, are recommended for use in tape casting processes.

A typical tape casting formulation based on 100 g of solid ceramic powder is shown in Table 20.

Table 20. Typical tape casting formulation Component Parts by weight

Alumina 100.0

Butvar B-79 5.0

Santicizer® 160 4.3

Blown Menhaden Oil Z-3 visc. 2.0

Toluene 14.4

MEK 14.4

Premix the fish oil in the toluene and MEK and add to ball mill. Add Alumina and ball mill for 1 hour. Add Santicizer 160 and Butvar B-79. Mill an additional 24 hours. Pour, de-air for several minutes, and cast.

• Additional Butvar can be added to most formulations to improve interfilm lamination in a multilayer substrate.

• A microfiltration system is generally used with binder/solvent systems. A 5-micron or finer filter is recommended.

Thick filmsButvar resins can be used as the binder medium in vehicle formulations for thick film pastes. Our lowest-molecular-weight resins, Butvar B-79 and B-98, are recommended for either silk screen or steel screen processes. The advantages of using Butvar in thick films include:

• Butvar is an excellent binder and dispersant for the conductive metals used in thick films.

• Thick films with Butvar can be cofired with the green tape in laminated ceramic substrates.

• Binder compatibility problems are minimized for cofiring systems when Butvar is used in both thick film processing and as the binder in the ceramic tape casting process.

Table 21. Thermal properties

UnitsTest

method

Butvar B-76 B-79

Butvar B-90 B-98

Glass transition temperature (Tg)

°C DSC 62–72 72–78

Ash content at 550°C

In nitrogen % TGA <2.0 <3.0

In air % TGA <0.75 <0.75

The apparent glass transition temperature (Tg) was determined by differential scanning calorimeter (DSC). The thermal gravimetric analysis (TGA) was a weight loss versus temperature profile conducted at a heating rate of 10°C/min.

27

Toners and printing inksButvar resins have been used in printing ink formulations for many years. All Butvar resins are alcohol soluble and are often used in solvent-based gravure and flexographic ink formulations to improve flexibility, adhesion, and toughness. The solubility characteristics of Butvar B-79 and B-76 in aromatic and other fast-drying solvents allow for compounding at low concentrations in high-speed, high quality printing applications. These properties have also enabled Butvar to be used in ink formulations for thick film conductive pastes, printer ribbons, and pen inks, as well as in the manufacture of offset printing plates and other printing technology apparatus.

Butvar also serves the toner industry as a secondary binder. Polyvinyl butyral is added to the formulations to increase viscosity and improve film integrity over the fuser roll. The overall toughness of Butvar enhances the integrity of the toner during the milling process and extended machine operation. This minimizes the level of fines without detracting from the flow properties.

Graph 11. Butvar® resin thermolysis profiles: thermal gravimetric analysis (TGA)

Graph 12. Butvar® resin thermolysis profiles: thermal gravimetric analysis (TGA)

In nitrogen

In air

100

90

80

70

60

50

40

30

20

10

050 100 150 200 250 300 350 400 450 500 550

Wei

ght

(wt%

)

Temperature (ºC) Heating rate: 10ºC/min

100

90

80

70

60

50

40

30

20

10

050 100 150 200 250 300 350 400 450 500 550

Wei

ght

(wt%

)Temperature (ºC) Heating rate: 10ºC/min

100

90

80

70

60

50

40

30

20

10

050 100 150 200 250 300 350 400 450 500 550

Wei

ght

(wt%

)

Temperature (ºC) Heating rate: 10ºC/min

100

90

80

70

60

50

40

30

20

10

050 100 150 200 250 300 350 400 450 500 550

Wei

ght

(wt%

)

Temperature (ºC) Heating rate: 10ºC/min

28

Storage and handlingStorage Environments of high heat and humidity should be avoided.

Toxicity and FDA statusButvar® resins are regulated by the U. S. Food and Drug Administration under parts of Title 21 of the Code of Federal Regulations for use as indirect food additives. Butvar resin has also been subjected to acute toxicity and mutagenicity studies. Details on specific coverage of individual studies are available on request.

Table 22. Packaging information

Container type B-72 B-90, B-76 B-98, B-79, B-74

61-gallon fiber drum 145 lb (66 kg) 140 lb (63 kg) 135 lb (61 kg)

Quality controlTo obtain the outstanding quality characteristics of Butvar, Eastman maintains statistical process control over the manufacturing process. In addition, to ensure that you receive highly uniform material with each shipment, the finished product is analyzed in detail to be certain it conforms to our rigid specifications.

29

Material sourcesProduct designation Owner and/or supplier

Araldite 6069 Novartis Corporation

Basic zinc chromateLansco Colors Rockwood Pigments NA, Inc.

Beckosol 11-035 Reichhold Chemicals, Inc.

Blown Menhaden Oil Z-3 visc.Werner G. Smith Inc. R.E. Mistler, Inc.

Borogard ZB U.S. Borax

2-Butoxyethanol (Eastman EB solvent) Eastman Chemical Company

Butvar® resins Eastman Chemical Company

Butyl acetate Eastman Chemical Company

Butyl alcohol Eastman Chemical Company

Butyl benzyl phthalate Ferro Corporation

Castor Oil #1 (raw), #15, #30, #40 CasChem Inc.

Castorwax CasChem Inc.

Celite 266 Imerys Filtration

Cellulose acetate Eastman Chemical Company

Cellulose acetate butyrate Eastman Chemical Company

Chlorinated rubber Ashland, Inc.

Chromic acid (chromium trioxide) J.T. Baker Inc.

DC 840 Dow Corning Corporation

DCZ 6018 Dow Corning Corporation

Desmodur AP stabil Covestro

Diacetone alcohol Shell Chemical Corporation

Dibutyl phthalate BASF

Dibutyl sebacate HallStar

Dihexyl adipate Ferro Corporation

Dimethyl esters Invista

Dioctyl phthalate Eastman Chemical Company

Duraplex 11-804 Reichhold Chemicals, Inc.

Durite P-97, LS-433 Hexion

EPI-REZ 540-C Solvay

EPON 1001F, 1007F Momentive

2-Ethylhexyl diphenyl phosphate Ferro Corporation

Flexricin-P3 CasChem Inc.

Furnace black Columbian Chemicals

Hercolyn Pinova Solutions

Isophorone Dow Chemical Company

Isopropanol Eastman Chemical Company

Ketjenflex 8, 9S, MH Axcentive

Product designation Owner and/or supplier

Linseed oilArista Chemical Inc. Reichhold Chemicals, Inc.

Magnesium silicate MP40-27 Specialty Minerals

Methyl acetate Eastman Chemical Company

Methyl alcohol Air Products and Chemicals Inc.

Methyl ethyl ketone Shell Chemical Corporation

Methyl isobutyl ketone Eastman Chemical Company

Methylon 75-108 OxyChem

Moly-White X92 Sherwin-Williams Chemical

Naphtha Shell Chemical Corporation

Nitrocellulose RS, SS Dow Wolff Cellulosics

OxyChem 02620, 92600, 29107 OxyChem

p-Nonylphenol Boddin Chemiehandel

Paraplex® RGA-8 HallStar

Pentalyn H Eastman Chemical Company

PhosGuard® J-0800 Rockwood Pigments NA, Inc.

Phosphoric acid, 85% U.S.P. ICL Performance Products Lp.

Plyophen 22-023 OxyChem

Poly-Pale™ rosin resins Eastman Chemical Company

Pycal 94 ICI Americas Inc.

Resimene® 717, 730, 741, 881 AQ-7550 and 918 Cytec Ind.

SP-1044 resin SI Group

Santicizer® plasticizers Ferro Corporation

Santolink® EP-560 Cytec Ind.

Shellac RPM International Inc.

Staybelite-E™ hydrogenated rosin Eastman Chemical Company

Tributyl citrate Morflex Chemical Company

Tricresyl phosphateFMC Corporation AkzoNobel

Triethylene glycol di-2-ethylhexanoate (Eastman™ TEG-EH)

Eastman Chemical Company

Triphenyl phosphate Triway

Vinyl chloride copolymer VAGH,VAGD (UCAR solution vinyl resin) Dow Chemical Company

Vinsol Pinova Solutions

Xylol (xylene) Exxon Company, U.S.A.

Zinc borate U.S. Borax

Zinc borophosphate Rockwood Pigments NA, Inc.

Zinc molybdate Sherwin-Williams Chemical

ADD-BVR-3978 3/17

Although the information and recommendations set forth herein are presented in good faith, Eastman Chemical Company and its subsidiaries make no representations or warranties as to the completeness or accuracy thereof. You must make your own determination of its suitability and completeness for your own use, for the protection of the environment, and for the health and safety of your employees and purchasers of your products. Nothing contained herein is to be construed as a recommendation to use any product, process, equipment, or formulation in conflict with any patent, and we make no representations or warranties, express or implied, that the use thereof will not infringe any patent. NO REPRESENTATIONS OR WARRANTIES, EITHER EXPRESS OR IMPLIED, OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR OF ANY OTHER NATURE ARE MADE HEREUNDER WITH RESPECT TO INFORMATION OR THE PRODUCT TO WHICH INFORMATION REFERS AND NOTHING HEREIN WAIVES ANY OF THE SELLER’S CONDITIONS OF SALE.

Safety Data Sheets providing safety precautions that should be observed when handling and storing our products are available online or by request. You should obtain and review available material safety information before handling our products. If any materials mentioned are not our products, appropriate industrial hygiene and other safety precautions recommended by their manufacturers should be observed.

© 2017 Eastman Chemical Company. Eastman brands referenced herein are trademarks of Eastman Chemical Company or one of its subsidiaries or are being used under license. The ® symbol denotes registered trademark status in the U.S.; marks may also be registered internationally. Non-Eastman brands referenced herein are trademarks of their respective owners.

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