Modified polyvinyl acetal resin composition

Abstract

The present invention aims to provide a modified polyvinyl acetal resin composition that is excellent in storage stability, has high strength and excellent adhesiveness, and is capable of reducing occurrence of warping or peeling when used for bonding different materials. The present invention relates to a modified polyvinyl acetal resin composition containing: a modified polyvinyl acetal resin having a constitutional unit with an imine structure, and an epoxy resin.

Claims

1. A modified polyvinyl acetal resin composition comprising: a modified polyvinyl acetal resin having a constitutional unit with an imine structure, and an epoxy resin, wherein the amount of the constitutional unit with an imine structure in the modified polyvinyl acetal resin is 0.1 to 20.0 mol % relative to the modified polyvinyl acetal resin.

2. The modified polyvinyl acetal resin composition according to claim 1, wherein the modified polyvinyl acetal resin further has a constitutional unit with an amino group or an amide structure.

3. The modified polyvinyl acetal resin composition according to claim 2, wherein the modified polyvinyl acetal resin has an amino group or an amide structure, and an imine structure in a side chain.

4. The modified polyvinyl acetal resin composition according to claim 2, wherein the total amount of the constitutional unit with an imine structure and the constitutional unit with an amino group or an amide structure in the modified polyvinyl acetal resin is 0.1 to 20 mol %.

5. The modified polyvinyl acetal resin composition according to claim 1, wherein the modified polyvinyl acetal resin has a degree of acetalization of 60 to 90 mol %.

6. The modified polyvinyl acetal resin composition according to claim 1, wherein the modified polyvinyl acetal resin is an acetalization product of polyvinyl alcohol having a constitutional unit with an amino group or an amide structure.

7. The modified polyvinyl acetal resin composition according to claim 1, wherein the amount of the constitutional unit with an imine structure in the modified polyvinyl acetal resin is 0.5 to 20.0 mol % relative to the modified polyvinyl acetal resin.

8. The modified polyvinyl acetal resin composition according to claim 1, wherein the amount of the constitutional unit with an imine structure in the modified polyvinyl acetal resin is 1.0 to 20.0 mol % relative to the modified polyvinyl acetal resin.

Description

DESCRIPTION OF EMBODIMENTS

(1) The present invention is more specifically described in the following with reference to, but not limited to, the following examples.

Example 1

(2) An amount of 240 g of polyvinyl alcohol having a degree of polymerization of 600 and a degree of saponification of 99.7 mol % and containing 1.7 mol % of a constitutional unit with an amino group (NH.sub.2) represented by the above formula (3) was added to 1,800 g of pure water, and stirred at 90 C. for about two hours to be dissolved. The solution was cooled to 40 C., and to the solution were added 170 g of hydrochloric acid having a concentration of 35% by weight and 275 g of n-butyraldehyde. The acetalization reaction was carried out to precipitate a reaction product by maintaining the solution temperature at 40 C.

(3) Then, the reaction solution was held to maintain the temperature at 40 C. for three hours, thereby completing the reaction. A modified polyvinyl acetal resin powder was obtained through neutralization, washing with water, and drying by normal methods.

(4) The obtained modified polyvinyl acetal resin was dissolved in DMSO-d.sub.6 (dimethylsulfoxide), and analyzed by .sup.13C-NMR (nuclear magnetic resonance spectrum) to confirm the presence of the constitutional unit with an amino group represented by the above formula (3) (amount: 0.2 mol %) and the constitutional unit with an imine structure represented by the following formula (5) (amount: 1.5 mol %, in the formula (5), R.sup.3 is a hydrogen atom and R.sup.4 is an n-butyl group).

(5) Table 1 shows the degree of butyralization, acetyl group content, and hydroxy group content measured by .sup.13C-NMR.

(6) ##STR00004##

(7) A polyvinyl acetal resin solution was prepared by dissolving 10 g of the obtained modified polyvinyl acetal resin in 90 g of a mixed solvent prepared by mixing toluene and ethanol at a weight ratio of 1:1.

(8) To the obtained polyvinyl acetal resin solution was added 90 g of neopentyl glycol diglycidyl ether (epoxy equivalent: 108, molecular weight: 216), thereby preparing a resin composition containing a polyvinyl acetal resin and an epoxy resin mixed at a weight ratio of 10:90.

(9) The obtained resin composition was applied to a release-treated polyethylene terephthalate (PET) film to a dry thickness of 20 m, and dried at 125 C. to prepare a resin sheet.

Example 2

(10) A modified polyvinyl acetal resin was obtained in the same manner as in Example 1, except that the polyvinyl alcohol used was changed to 240 g of polyvinyl alcohol having a degree of polymerization of 600 and a degree of saponification of 99.7 mol % and containing 16.0 mol % of a constitutional unit with an amino group represented by the above formula (3), and the amount of n-butyraldehyde was changed to 224 g.

(11) The obtained modified polyvinyl acetal resin was dissolved in DMSO-d.sub.6 (dimethylsulfoxide), and analyzed by .sup.13C-NMR (nuclear magnetic resonance spectrum) to confirm the presence of the constitutional unit with an amino group represented by the above formula (3) (amount: 0.2 mol %) and the constitutional unit with an imine structure represented by the above formula (5) (amount: 15.8 mol %, in the formula (5), R.sup.3 is a hydrogen atom and R.sup.4 is an n-butyl group).

(12) Table 1 shows the degree of butyralization, acetyl group content, and hydroxy group content measured by .sup.13C-NMR.

(13) A polyvinyl acetal resin solution, a resin composition, and a resin sheet were produced using the obtained modified polyvinyl acetal resin in the same manner as in Example 1.

Example 3

(14) A modified polyvinyl acetal resin was obtained in the same manner as in Example 1, except that the polyvinyl alcohol used was changed to 240 g of polyvinyl alcohol having a degree of polymerization of 600 and a degree of saponification of 99.7 mol % and containing 0.5 mol % of a constitutional unit with an amino group represented by the above formula (3), and the amount of n-butyraldehyde was changed to 280 g.

(15) The obtained modified polyvinyl acetal resin was dissolved in DMSO-d.sub.6 (dimethylsulfoxide), and analyzed by .sup.13C-NMR (nuclear magnetic resonance spectrum) to confirm the presence of the constitutional unit with an amino group represented by the above formula (3) (amount: 0.0 mol %) and the constitutional unit with an imine structure represented by the above formula (5) (amount: 0.5 mol %, in the formula (5), R.sup.3 is a hydrogen atom and R.sup.4 is an n-butyl group).

(16) Table 1 shows the degree of butyralization, acetyl group content, and hydroxy group content measured by .sup.13C-NMR.

(17) A polyvinyl acetal resin solution, a resin composition, and a resin sheet were produced using the obtained modified polyvinyl acetal resin, in the same manner as in Example 1.

Example 4

(18) A polyvinyl acetal resin solution, a resin composition, and a resin sheet were produced in the same manner as in Example 1, except that 90 g of neopentyl glycol diglycidyl ether was changed to 90 g of a bisphenol A-type epoxy resin (jER 828 available from Mitsubishi Chemical Corporation, epoxy equivalent: 190, molecular weight: 380).

Example 5

(19) A polyvinyl acetal resin solution, a resin composition, and a resin sheet were produced in the same manner as in Example 2, except that 90 g of neopentyl glycol diglycidyl ether was changed to 90 g of a bisphenol A-type epoxy resin (jER 828 available from Mitsubishi Chemical Corporation).

Example 6

(20) A polyvinyl acetal resin solution, a resin composition, and a resin sheet were produced in the same manner as in Example 3, except that 90 g of neopentyl glycol diglycidyl ether was changed to 90 g of a bisphenol A-type epoxy resin (jER 828 available from Mitsubishi Chemical Corporation).

Examples 7 to 9

(21) A polyvinyl acetal resin solution, a resin composition, and a resin sheet were produced in the same manner as in Example 1, except that the modified polyvinyl acetal resin obtained in Example 1 was used and an epoxy resin, a curing agent, and a curing accelerator were added as specified in Table 1.

(22) The epoxy resin used was listed below.

(23) Bisphenol F-type epoxy resin (jER 807 available from Mitsubishi Chemical Corporation, epoxy equivalent: 170)

(24) Polypropylene glycol diglycidyl ether (EX-920 available from Nagase ChemteX Corporation, epoxy equivalent: 176)

Example 10

(25) A polyvinyl acetal resin solution, a resin composition, and a resin sheet were produced in the same manner as in Example 2, except that 90 g of neopentyl glycol diglycidyl ether was changed to 90 g of a bisphenol F-type epoxy resin (jER 807 available from Mitsubishi Chemical Corporation).

Example 11

(26) A polyvinyl acetal resin solution, a resin composition, and a resin sheet were produced in the same manner as in Example 3, except that 90 g of neopentyl glycol diglycidyl ether was changed to 90 g of a bisphenol F-type epoxy resin (jER 807 available from Mitsubishi Chemical Corporation).

Comparative Example 1

(27) A polyvinyl acetal resin was obtained in the same manner as in Example 1, except that the polyvinyl alcohol was changed to polyvinyl alcohol having a degree of polymerization of 600 and a degree of saponification of 99.5 mol %.

(28) The obtained polyvinyl acetal resin was dissolved in DMSO-d.sub.6 (dimethylsulfoxide), and analyzed by .sup.13C-NMR (nuclear magnetic resonance spectrum), failing to confirm the presence of a constitutional unit with an amino group or a constitutional unit with an imine structure.

(29) Table 1 shows the degree of butyralization, acetyl group content, and hydroxy group content measured by .sup.13C-NMR.

(30) A polyvinyl acetal resin solution was produced by dissolving 30 g of the obtained polyvinyl acetal resin in a mixed solvent prepared by mixing toluene and ethanol at a weight ratio of 1:1.

(31) A resin composition and a resin sheet were produced in the same manner as in Example 1, except that to the obtained polyvinyl acetal resin solution was added 70 g of neopentyl glycol diglycidyl ether and a resin composition was produced by mixing the polyvinyl acetal resin and an epoxy resin at a weight ratio of 30:70.

Comparative Examples 2 and 3

(32) A polyvinyl acetal resin solution, a resin composition, and a resin sheet were produced in the same manner as in Example 1, except that the polyvinyl acetal resin obtained in Comparative Example 1 was used, and an epoxy resin, a curing agent, and a curing accelerator were added as specified in Table 1.

(33) <Evaluation>

(34) The polyvinyl acetal resin compositions and resin sheets obtained in the examples and comparative examples were evaluated for the following parameters. Table 2 shows the results.

(35) (1) Gel Fraction

(36) To about 0.1 g (w1) of a sample of a resin sheet was added 40 g of a mixed solvent prepared by mixing toluene and ethanol at a weight ratio of 1:1, and the mixture was stirred for 24 hours so that the sample was dissolved again. Then, solid-liquid separation was performed using a 200-mesh stainless-steel sieve whose mass (w2) was measured in advance. The stainless-steel sieve was taken out and vacuum-dried at 100 C. for one hour, followed by measurement of the mass (w3) thereof. The gel fraction was calculated using the following equation.
Gel fraction (%)={(w3w2)/w1}100.

(37) The obtained gel fraction was evaluated based on the following criteria.

(38) A higher gel fraction indicates higher curability.

(39) (Excellent): 80% or higher

(40) (Good): 40% or higher and lower than 80%

(41) (Average): 10% or higher and lower than 40%

(42) x (Poor): Lower than 10%

(43) (2) Storage Stability

(44) An amount of 10 g of the resin composition was dissolved in 90 g of a mixed solvent prepared by mixing toluene and ethanol at a weight ratio of 1:1, thereby preparing a sample solution. The viscosity of the obtained sample solution was measured immediately after the preparation of the sample solution and a month later using a B-type viscometer to obtain the change rate of the solution viscosity. The obtained change rate was evaluated based on the following criteria.

(45) (Excellent): Lower than 10%

(46) (Good): 10% or higher and lower than 20%

(47) (Average): 20% or higher and lower than 30%

(48) x (Poor): 30% or higher

(49) (3) Adhesive Force to a Base

(50) The obtained polyvinyl acetal resin composition was applied to various metal bases, and heated at 160 C. for 60 minutes to be cured. A cross-cut adhesion test was performed in conformity with JIS K 5400, and the number of grids on which the composition was remaining after the test was counted to evaluate the adhesive force to each base.

(51) The metal bases used were an aluminum base, a stainless steel (SUS304) base, and a SPCC steel base.

(52) With a higher adhesive force to a base, warping or peeling is less likely to occur upon curing.

(53) (4) Tensile Modulus of Elasticity, Degree of Elongation, Yield Point Stress

(54) The obtained resin sheet was peeled from the PET film, and the tensile modulus of elasticity (MPa), degree pf elongation (%), and yield point stress (MPa) of the peeled sheet were measured at a tensile speed of 20 mm/min by a method in conformity with JIS K 7113 using an autograph (AGS-1 available from Shimadzu Corporation).

(55) (5) Shear Adhesive Force

(56) The obtained polyvinyl acetal resin composition was applied to various metal bases, and heated at 160 C. for 60 minutes to be cured. The shear adhesive force thereof was measured under the conditions of a temperature of 20 C. to 30 C. and a tensile speed of 5 mm/min by a method in conformity with JIS K 6850.

(57) The metal bases used were an aluminum base, a stainless steel (SUS304) base, and a SPCC steel base.

(58) With a higher shear adhesive force, peeling is less likely to occur even under application of an external force, which indicates that the excellent adhesive force is achieved.

(59) TABLE-US-00001 TABLE 1 Polyvinyl acetal resin Amount of Amount of constitutional Adhesive Acetyl Hydroxy constitutional unit with composition Degree of group group unit with imine Added Degree of butylarization content content amino group structure amount of polymerization (mol %) (mol %) (mol %) (mol %) (mol %) PVB (g) Example 1 600 77.5 0.3 20.5 0.2 1.5 10 Example 2 600 63.2 0.3 20.5 0.2 15.8 10 Example 3 600 78.7 0.3 20.5 0 0.5 10 Example 4 600 77.5 0.3 20.5 0.2 1.5 10 Example 5 600 63.2 0.3 20.5 0.2 15.8 10 Example 6 600 78.7 0.3 20.5 0 0.5 10 Example 7 600 77.5 0.3 20.5 0.2 1.5 10 Example 8 600 77.5 0.3 20.5 0.2 1.5 10 Example 9 600 77.5 0.3 20.5 0.2 1.5 10 Example 10 600 63.2 0.3 20.5 0.2 15.8 10 Example 11 600 78.7 0.3 20.5 0 0.5 10 Comparative 600 79.0 0.5 20.5 0.0 0.0 30 Example 1 Comparative 600 79.0 0.5 20.5 0.0 0.0 10 Example 2 Comparative 600 79.0 0.5 20.5 0.0 0.0 10 Example 3 Adhesive composition Epoxy resin (g) Neopentyl Polypropylene Curing Bisphenol Bisphenol glycol glycol Curing agent accelerator (g) A-type F-type diglycidyl diglycidyl (g) Imidazole epoxy resin epoxy resin ether ether dicyandiamide compound Example 1 90 Example 2 90 Example 3 90 Example 4 90 Example 5 90 Example 6 90 Example 7 75 10 3 2 Example 8 75 10 3 2 Example 9 90 Example 10 90 Example 11 90 Comparative 70 Example 1 Comparative 75 10 3 2 Example 2 Comparative 75 10 3 2 Example 3

(60) TABLE-US-00002 TABLE 2 Evaluation Strength of composition Adhesive force Tensile Yield Shear adhesive to base (number) modulus of Degree of point force (N/300 mm.sup.2) Gel Storage SUS SPCC elasticity elongation stress SUS SPCC fraction stability Aluminum 304 steel (Mpa) (%) (Mpa) Aluminum 304 steel Example 1 6 6 6 1000 40 75 800 1000 1000 Example 2 10 10 10 1200 30 85 1200 1400 1400 Example 3 4 6 6 900 50 70 800 1200 1200 Example 4 6 6 6 1200 30 85 1300 1500 1550 Example 5 10 10 10 1350 25 90 1550 1800 1850 Example 6 6 4 4 950 46 70 1000 1300 1300 Example 7 10 10 10 1500 25 90 4000 4800 5000 Example 8 10 10 10 1700 15 90 4200 5000 5200 Example 9 6 6 6 1300 35 85 1300 1500 1600 Example 10 10 10 10 1400 35 95 1450 1750 1900 Example 11 6 4 4 1000 55 80 1000 1300 1300 Comparative X 2 4 4 500 10 55 300 500 500 Example 1 Comparative X 4 4 4 1000 5 60 600 800 850 Example 2 Comparative X 4 6 6 1200 5 65 650 800 850 Example 3

INDUSTRIAL APPLICABILITY

(61) The present invention can provide a modified polyvinyl acetal resin composition that is excellent in storage stability, has high strength and excellent adhesiveness, and is capable of reducing warping or peeling when used for bonding different materials.