Butvar® polyvinyl butyral resin Properties and uses Contents Contents 1 Introduction 21 Wood finishes 1 Uses 21 Protective wash coats and sealers 1 Technical support for specific applications 21 Knot sealers 22 Adhesives 2 Properties 22 Structural adhesives 2 Chemistry 22 Phenolic resins 6 Product types 22 Expoxies and other thermosetting resins 6 Butvar: the right resin solution 23 High-strength bonding procedure 13 Compatibility 23 Performance characteristics 15 Insolubilizing reactions 23 Adhesive strengths 17 Applications 24 Hot melt adhesives 17 Wire enamels 24 Textile coatings 17 Surface coatings 24 Advantages as textile coating 17 Wash primers 25 Ceramic binder applications 17 Military specification wash primers 26 Tape casting 18 Nonspecification wash primers: 26 Thick films B-1030 with Butvar 27 Toners and printing inks 18 Single-package wash primer: 28 Storage and handling B-1011 with Butvar 28 Storage 19 Chromate-free wash primers with Butvar 28 Toxicity and FDA status 20 Metal coatings 28 Quality control 29 Material sources Introduction Polyvinyl butyral resins are employed in Uses a wide array of industrial and commercial Some of the applications in which Butvar is a vital applications. These unique resins offer ingredient include: impressive performance, as well as • Ceramic binders outstanding versatility. • Inks/dry toners • Wood coatings Butvar® polyvinyl butyral resins have a combination of properties that make them a key ingredient in a variety of • Wash primers successful formulations. Some of these properties for which • Composite fiber binders Butvar is widely used are outstanding binding efficiency, • Structural adhesives optical clarity, adhesion to a large number of surfaces, and • Other diverse uses toughness combined with flexibility. Butvar resin was pioneered by Monsanto in the 1930s as Solutia offers six grades of Butvar resins that cover a broad the key ingredient for automotive safety glass interlayers. range of chemical and physical properties. These resins It still enjoys widespread use in automotive and are generally well suited either as a major ingredient of architectural applications for laminated safety glass. a formulation or in smaller quantities to enhance the properties of other resins. Technical support for specific applications Solutia’s technical support and research staff for Butvar resins can assist in your specific application needs. The Customer Service Center at 1-800-964-5224 stands ready to receive your orders for samples and technical literature, as well as purchase orders for shipment of Butvar resin. 1 Properties Chemistry The conditions of the acetal reaction and the concentration of the particular aldehyde and polyvinyl alcohol used are Acetals, such as polyvinyl butyral, are formed by the closely controlled to form polymers containing predetermined well-known reaction between aldehydes and alcohols. The proportions of hydroxyl, acetate, and acetal groups. The final addition of one molecule of an alcohol to one molecule of product may be represented by the following stylized structure. an aldehyde produces a hemiacetal. Hemiacetals are rarely isolated because of their inherent instability but, rather, are The proportions of A, B, and C are controlled, and they are further reacted with another molecule of alcohol to form a randomly distributed along the molecule. 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. H H H 1 1 1 R — C + R — OH R — C — OR + R — OH R — C (— OR )2 + H2O O Alcohol OH Alcohol Aldehyde Hemiacetal Acetal H H H CH2 H CH — C CH — C CH2 — C C 2 2 OO OH O C C O H C3H7 CH3 A B C PV Butyral PV Alcohol PV Acetate 2 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 — (1) 170–250 120–150 90–120 50–80 70–100 40–70 average in thousands) Solution viscosity cp (2) 7,000–14,000 3,000–7,000 500–1,000 100–400 600–1,200 200–400 15% by weight Solution viscosity cp (2) 1,600–2,500 800–1,300 200–450 75–200 200–400 75–200 10% by weight Ostwalda solution cp (3) 170–260 37.0–47.0 18.0–28.0 9.0–16.0 13.0–17.0 6.0–9.0 viscosity Specific gravity — D792–50 1.100 1.100 1.083 1.083 1.100 1.100 23˚/23˚ (±0.002) Burning rate ipm D635–56T 1.0 1.0 1.0 1.0 0.9 0.9 Refractive index — D542–50 1,490 1.490 1.485 1.485 1.490 1.490 (±0.0005) Water absorption % D570–59aT 0.5 0.5 0.3 0.3 0.5 0.5 (24 hours) Hydroxyla content expressed as % — — 17.5–20.0 17.5–20.0 11.5–13.5 11.0–13.5 18.5–20.5 18.0–20.0 polyvinyl alcohol Acetate content expressed as % — — 0–2.5 0–2.5 0–2.5 0–2.5 0–2.5 0–2.5 polyvinyl acetate Butyral content expressed as % polyvinyl — — 80 80 88 88 80 80 butyral, approx. aSpecification properties All properties were determined by ASTM methods except the following: • Molecular weight was determined via size exclusion chromatography with low-angle laser light scattering (SEC/LALLS) method of Cotts and Ouano in tetra-hydrofuran.b • Solution viscosity was determined in 15% by weight solutions in 60:40 toluene: ethanol at 25˚C, using a Brookfield Viscometer. Also in 10% solution in 95% ethanol @ 25˚C using an Ostwald-Cannon- Fenske Viscometer. • Ostwald solution viscosity for each product type measured with an Ostwald.Cannon-Fenske Viscometer. The solvents and solids levels used are as follows: Percent Temperature Product solids Solvent (C˚) Anhydrous B-72 7.5 20 methanol SD 29 ethyl B-76, B-79 5.0 25 alcohol Anhydrous B-74, B-90, B-98 6.0 20 methanol bP. Dublin, ed., MicrodomainsMicrodomains In In Polymer Polymer Solutions Solutions (New (New York: York: Plenum Plenum Press, Press, 1985), 1985),pp. 101-119. pp. 101-119. 3 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 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 (apparent) 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, ft.lb./in. D256-56 1.1 1.1 0.8 0.8 0.9 80 notched ½" x ½" *Specification properties 4 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, ºC D569-59 145–155 135–145 110–115 110–115 125–130 105–110 1,000 psi Glass transition ºC (4) 72–78 72–78 62–72 62–72 72–78 72–78 temperature (Tg) Ash content at 550ºC: In nitrogen % (5) <3.0 <3.0 <2.0 <2.0 <3.0 <3.0 In air % (5) <1.0 <1.0 <0.75 <0.75 <0.75 <0.75 Heat distortion ºC D648-56 56–60 56–60 50–54 50–54 52–56 45–55 temperature Heat sealing temperature ºF (6) 220 220 200 200 205 200 • Glass transition temperature (Tg) was determined by Differential • Heat-sealing temperature was determined on a 1-mil dried film Scanning Calorimeter (DSC) over a range of 30˚C to 100˚C on dried on paper cast from a 10% solution in 60:40 toluene:ethanol. granular resin. A dwell time of 1.5 seconds at a 60 psi line pressure was used • Ash content of the Thermal Gravimetric Analysis (TGA) was on the heat sealer. determined as a weight loss versus temperature profile conducted at a heating rate of 10˚C/min. 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 cps — D150-59T 3.2 3.2 2.7 2.7 3.2 3.3 103 cps — D150-59T 3.0 3.0 2.6 2.6 3.0 3.0 106 cps — D150-59T 2.8 2.8 2.6 2.6 2.8 2.8 107 cps — D150-59T 2.7 2.7 2.5 2.5 2.7 2.8 Dissipation factor: 50 cps — D150-59T 0.0064 0.0064 0.0050 0.0050 0.0066 0.0064 103 cps — D150-59T 0.0062 0.0062 0.0039 0.0039 0.0059 0.0061 106 cps — D150-59T 0.027 0.027 0.013 0.013 0.022 0.023 107 cps — D150-59T 0.031 0.031 0.015 0.015 0.023 <0.24 Dielectric strength (l" 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 *Specification properties 5 Product types Butvar: the right resin solutions The properties of the various types of Butvar® resins are Butvar brand resins generally are soluble in alcohols, glycol described in Tables 1 through 5.