JP2009029936A - Crystalline oligomer, curable resin composition and adhesive sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein an adhesive composed of a phenol-formaldehyde resin has been used heretofore in various adhesion applications due to its good adhesive performance but its non-formaldehydation is demanded since diffused formaldehyde is regarded as a causal substance of the sick-house syndrome. <P>SOLUTION: The conventional problem relating to the phenolic resin could be solved by using a crystalline oligomer having a polymerizable unsaturated bond and a blocked isocyanate group which is solid at normal temperatures or a curable resin composition containing the same. By using an acid modified polyvinyl acetal as a polyvinyl acetal, a curable resin composition having higher adhesion, heat resistance, and water resistance could be obtained. The crystalline oligomer is obtained by reacting a compound having a hydroxyl group and a polymerizable unsaturated bond, a compound having an isocyanate group, and an agent for blocking the isocyanate group. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a crystalline oligomer, a curable resin composition, and an adhesive sheet.

  Adhesive sheets prepared by impregnating a curable resin composition with a porous substrate such as paper, cloth, or glass fiber do not require an application or drying process, and are heated by being interposed between the layers of the adherend. It was preferred because it can be bonded by simply applying pressure.

However, since formaldehyde and the like are the causative substances of sick house syndrome and were designated by the Ministry of Health, Labor and Welfare in 2002, non-formaldehyde conversion is required in all fields of application. In addition, phenolic resins as thermosetting resins are required to reduce contamination caused by volatilization and elution of unreacted phenols or mononuclear components from the viewpoint of air pollution and environmental protection. .
JP-A-10-279893 JP-A-8-238713 JP-A-6-240108 JP 11-34248 A

  The present invention responds to the above-mentioned demands, and does not employ phenol formaldehyde resin, melamine formaldehyde resin or other formaldehyde-dissipating resin from the viewpoint of sick house syndrome, air pollution, and environmental protection. It is an object of the present invention to provide an adhesive composition and an adhesive processed product that do not volatilize or dissolve.

  The present invention has been studied in view of such circumstances, and the invention according to claim 1 is a reaction between a compound having a hydroxyl group and a polymerizable unsaturated bond, a compound having an isocyanate group, and an isocyanate group blocking agent. It is a crystalline oligomer characterized by having a polymerizable unsaturated bond and a blocked isocyanate group. The invention according to claim 2 is that the compound having a hydroxyl group and a polymerizable unsaturated bond is at least one selected from the group consisting of (meth) acrylates having a primary hydroxyl group, allyl alcohol, allyl ether, and vinyl ether. The crystalline oligomer according to claim 1, which is characterized by the following. The invention described in claim 3 is a curable resin composition comprising the crystalline oligomer and polyvinyl acetal. The invention according to claim 4 is the curable resin composition according to claim 3, wherein the polyvinyl acetal is an acid-modified polyvinyl acetal. The invention according to claim 5 is an adhesive sheet obtained by impregnating or applying a fiber base material with the curable resin composition.

  Since the crystalline oligomer of the present invention is solid at room temperature, it is easy to handle, does not contain formaldehyde, which is a causative substance of sick house syndrome, and does not contain phenol formaldehyde resin, so it is air pollution or harmful to human body There is no contamination due to elution and volatilization of unreacted phenol required from the viewpoint of In addition, a polymerizable monomer having an unsaturated bond with a hydroxyl group, an isocyanate group blocking agent, and an isocyanate compound are reacted to obtain a crystalline oligomer, which is polymerized and cured and heated to dissociate the blocking agent, Since the group is reactivated, the water resistance, boiling resistance, and adhesion are excellent in bonding with a hydrophilic material such as wood. Further, by mixing with polyvinyl acetal, the isocyanate group reacts with the hydroxyl group in the polyvinyl acetal resin to form a three-dimensional network. Furthermore, by using acid-modified polyvinyl acetal containing a carboxylic acid group in the molecule, a curable resin composition having excellent metal adhesion, water resistance, and heat resistance can be obtained without adding a separate modifier. It is done. In addition, as shown in Table 4, stronger adhesive strength can be obtained in a shorter time than conventional phenol-based adhesive sheets. Hereinafter, the present invention will be described in detail.

  Examples of the polymerizable monomer having a hydroxyl group and an unsaturated bond include 2-hydroxyethyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, 4-hydroxybutyl (meth) acrylate, allyl alcohol, ethylene glycol monoallyl ether, polyethylene glycol Monoallyl ether, 1,4-cyclohexanedimethanol mono (meth) acrylate, 4-hydroxybutyl vinyl ether, and 2-hydroxyethyl vinyl ether are preferably used.

  As the compound having an isocyanate group, hexamethylene diisocyanate (HDI), 4,4′-diphenylmethane diisocyanate (4,4′MDI), bis (4-isocyanatocyclohexyl) methane, 2,4-toluene diisocyanate, 2,6- Toluene diisocyanate, 2,4-diphenylmethane diisocyanate, isophorone diisocyanate, tolidine diisocyanate, lysine isocyanate, 1,5-naphthylene diisocyanate, transcyclohexane 1,4-diisocyanate, 2,4-xylylene diisocyanate, hydrogenated xylylene diisocyanate M-tetramethylxylylene diisocyanate, p-tetramethylxylylene diisocyanate, and the like. Preferably, it is excellent in the crystallinity of the compound from which HDI, 4, 4 'MDI having a linear hydrocarbon structure between the diisocyanate groups and a symmetric linear structure is obtained.

  Examples of isocyanate group blocking agents include phenols, lactams, oximes, alcohols, active methylenes, benzotriazoles, mercaptans, acid amides, imides, amines, imidazoles and ureas. Can be mentioned. Specifically, oximes such as methyl ethyl ketone oxime (MEKO), acetone oxime, cyclohexanone oxime, acetophenone oxime, and benzophenone oxime, alcohols such as methanol, ethanol, propanol, isopropyl alcohol, butanol, 2-ethylhexanol, cyclohexanol, Examples thereof include lactams such as ε-caprolactam, γ-butyrolactam, and β-propiolactam, phenols, active methylene compounds such as acetylacetone, ethyl acetoacetate, methyl malonate, and ethyl malonate. Of these, MEKO is preferred in terms of addition reactivity to isocyanate groups and low-temperature dissociation properties.

  The molar ratio (number ratio) [H: NCO] of the isocyanate blocking group [H] of the blocking agent to the isocyanate group [NCO] of the compound having an isocyanate group is 90:10 to 1:99, more preferably 50:50. It is preferable to mix | blend so that it may become -1: 99. A part of the isocyanate group is reacted with a blocking agent, converted into a blocked isocyanate, and the resulting crystalline oligomer is polymerized and heated to dissociate the blocking agent, thereby activating the isocyanate group and allowing reaction. . When the amount of the blocking agent is larger than [H: NCO] = 90: 10, the polymerizability is lowered and the strength of the cured product is lowered. [H: NCO] = 1: 99 If the amount of the blocking agent is less than 1,99, there are few isocyanates that can be thermally dissociated and reactivated, resulting in a decrease in adhesion to water-soluble substances, water resistance, and heat resistance.

  Explaining the synthesis example of a crystalline oligomer solid at room temperature having a blocked isocyanate group and a polymerizable unsaturated bond, a hydroxyl group and a polymerizable unsaturated bond are added to a flask equipped with a stirrer, a thermometer, a condenser and a dropping device. After adding a compound having an isocyanate group and an isocyanate group blocking agent and raising the temperature, the compound having an isocyanate group and the blocking agent are dropped, and the resulting crystalline oligomer does not precipitate and is maintained at a temperature condition that does not polymerize and solidify. The mixture is stirred while being subjected to a urethanization reaction and an isocyanate group blocking reaction to obtain a crystalline oligomer mixture having a polymerizable unsaturated bond and a blocked isocyanate group at room temperature.

  As an example of application, polyvinyl acetal, polymerizable unsaturated, in order to make an adhesive sheet having excellent handleability, water resistance, heat resistance and adhesion to wood and metal using the above crystalline oligomer Paper and cloth made of various porous fiber materials that are dissolved in an organic solvent by combining a crystalline oligomer having a bond and a blocked isocyanate group at room temperature, a polymerization initiator, and if necessary a filler. It can be produced by impregnating a substrate such as glass fiber and drying. Moreover, it is also possible to use by heating and melting and coating without using an organic solvent.

  Polyvinyl acetal is obtained by reacting polyvinyl alcohol and various aldehydes to form an acetal. Polyvinyl formal using formaldehyde as an aldehyde, polyvinyl acetoacetal using acetaldehyde as an aldehyde, and polyvinyl butyral using butyraldehyde as an aldehyde are used industrially. Moreover, the polyvinyl acetal using the mixture of aldehydes is obtained. These polymer compositions have an acetal group, an acetyl group, and a hydroxyl group in the molecule. There are also acid-modified products having carboxylic acid groups in the molecule. In this invention, these polyvinyl acetals can be used individually or in mixture of 2 or more types. In particular, those having an acetalization degree of 60 to 90 mol% and a polymerization degree of 500 to 2500 are preferably used. When the degree of acetalization is less than 60 mol%, the heat resistance tends to be insufficient, and when it exceeds 90 mol%, the viscosity becomes too high, which is not preferable. For this reason, those having an acetalization degree of 65 to 85 mol% and a polymerization degree of 800 to 2500 are more preferably used. In particular, in order to further improve the adhesion to metals such as aluminum, iron, zinc, tin, copper, or adherends having a metal layer on the surface, acid-modified polyvinyl acetal having a carboxylic acid group in the molecule should be used. High adhesion and durability can be obtained.

  For example, commercially available products are available from ESREC BL-1, BL-1H, BL-2, BL-2H, BL-5, BL-10, BL-S, BX-L, BM-1, BM-2, BM- 5, BM-S, BH-3, BH-6, BH-A, BH-S, BX-1, BX-3, BX-5, KS-1, KS-3, KS-5, KS-10 ( Sekisui Chemical Co., Ltd. product name), Denkabutyral # 3000-1, # 3000-2, # 3000-4, # 3000-K, # 4000-2, # 5000A, # 5000-D, # 6000-C, # 6000-EP, # 6000-CS (named above, product name of Denki Kagaku Kogyo Co., Ltd.), vinylec (product name of Chisso Corporation), etc. These may be used alone or in combination.

  The blending range of the crystalline oligomer having a polymerizable unsaturated bond and a blocked isocyanate group with respect to polyvinyl acetal at a room temperature is from 90 parts by weight of the former to 10 parts by weight of the latter to 10 parts by weight of the latter to 90 parts by weight of the latter. Used in range. Less than 90 parts by weight of the former and less than 10 parts by weight of the latter is not preferable because problems such as poor heat resistance occur. On the other hand, if it exceeds 10 parts by weight of the former versus 90 parts by weight of the latter, it is not preferable because the adhesive strength is lowered.

  Any polymerization initiator may be used as long as it causes polymerization of a crystalline oligomer melted by heating, or a reactive monomer. Specific examples include organic peroxides such as ketone peroxides, peroxyketals, dialkyl peroxides, diacyl peroxides, peroxyesters and peroxydicarbonates, and azos such as azobisisobutyronitrile. Compounds.

  As other additives, reactive monomers can be used as long as handling properties such as stickiness are not impaired for the purpose of adjusting flow properties, crosslinking density, and improving adhesion to an adherend. Specific examples include 2-hydroxyethyl (meth) acrylate, dipentaerythritol hexa (meth) acrylate, diallyl phthalate, and the like. In order to further improve the adhesion to a metal such as aluminum or copper, or an adherend having a metal layer on the surface, a silane coupling agent or a phosphate group-containing polymerizable monomer within a range not deteriorating water resistance. It is possible to blend phosphoric acid-based and carboxylic acid compounds such as (meth) acryloyloxyethyl acid phosphate, fumaric acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid. In addition, a blocked isocyanate compound having no unsaturated double bond can be added to improve adhesion, water resistance and heat resistance.

In order to further promote crystallization and prevent stickiness during handling, inorganic fine powders such as fumed silica and talc, fillers such as calcium carbonate and aluminum hydroxide, dioctyl adipate and dibutyl to improve flexibility Plasticizers such as sebacate, dicyclohexyl phthalate, triethyleneglycol-2-ethylbutyral, triethyleneglycol-2-ethylhexoate, unsaturated polyester to improve impact resistance, storage stability In order to improve this, a polymerization inhibitor such as hydroquinone can be blended.
Synthesis Example Synthesis Example 1 2 in a 2 liter separable flask equipped with a polymerizable oligomer stirrer having a polymerizable unsaturated double bond and a blocked isocyanate group, a thermometer, a fraction condensing condenser (condenser), and a dropping device. -208 g (1.6 mol) of hydroxyethyl methacrylate, 34.8 g (0.4 mol) of methyl ethyl ketone oxime and 0.13 g of di-n-butyltin dilaurate as a urethanization catalyst were added and stirred, and the temperature was raised to 70 ° C. .

168 g (1 mol) was added while adjusting the dropping rate of hexamethylene diisocyanate (HDI) so that the internal temperature was 90 ° C. or lower. After completion of dropping, the reaction solution was sampled while maintaining the internal temperature at 80 ° C., and when it was confirmed by FTIR that the absorption peak at 2275 cm ⁻¹ based on the isocyanate group had disappeared, the reaction solution was transferred to a cooling vat. And crystallized and solidified to obtain a crystalline oligomer (1) solid at room temperature having a polymerizable unsaturated bond and a blocked isocyanate group. The melting point was 69 ° C. according to the endothermic peak tip temperature measurement method by DTA measurement (temperature increase rate: 10 ° C./min).

Synthesis Example 2 Crystalline oligomer having polymerizable unsaturated double bond and blocked isocyanate group 4, 4 in 4 liter separable flask equipped with stirrer, thermometer, fraction condensing condenser (condenser) and dropping device '250 g (1 mol) of diphenylmethane diisocyanate was charged and stirred and heated to 50 ° C. A mixture of 208 g (1.6 mol) of 2-hydroxyethyl methacrylate and 34.8 g (0.4 mol) of methyl ethyl ketone oxime was charged into the dropping device, and the mixture was adjusted while adjusting the dropping speed so that the internal temperature was 95 ° C. or lower. Was added. After completion of dropping, the reaction solution was sampled while maintaining the internal temperature at 95 ° C., and when it was confirmed by FTIR that the absorption peak at 2275 cm ⁻¹ based on the isocyanate group had disappeared, the reaction solution was transferred to a cooling vat. And crystallized and solidified to obtain a crystalline oligomer mixture (2) solid at room temperature having a polymerizable unsaturated bond and a blocked isocyanate group. The melting point was 76 ° C. according to the endothermic peak tip temperature measurement method by DTA measurement (temperature increase rate, 10 ° C./min).

Synthesis Example 3 260 g of 2-hydroxyethyl methacrylate was added to a 2 liter separable flask equipped with a crystalline oligomer stirrer having a polymerizable unsaturated double bond, a thermometer, a fraction condensation condenser (condenser), and a dropping device. (2 mol) and 0.13 g of di-n-butyltin dilaurate as a urethanization catalyst were added and stirred, and the temperature was raised to 70 ° C. 168 g (1 mol) was added while adjusting the dropping rate of hexamethylene diisocyanate (HDI) so that the internal temperature was 90 ° C. or lower. After completion of dropping, the reaction solution was sampled while maintaining the internal temperature at 80 ° C., and when it was confirmed by FTIR that the absorption peak at 2275 cm ⁻¹ based on the isocyanate group had disappeared, the reaction solution was transferred to a cooling vat. And crystallized and solidified to obtain a crystalline oligomer (3) solid at room temperature having a polymerizable unsaturated bond. The melting point was 78 ° C. according to the endothermic peak tip temperature measurement method by DTA measurement (temperature increase rate: 10 ° C./min).

Examples 1-3
Crystalline oligomer (1) prepared in Synthesis Example 1, crystalline oligomer (2) prepared in Synthesis Example 2, and ESREC BM2 (Sekisui Chemical Co., Ltd., product name, butyralization degree 68 mol%, polymerization degree 850, acetal as polyvinyl acetal) Composition is polyvinyl brural derived from butyraldehyde, Tg 67 ° C.), 2-methacryloyloxyethyl acid phosphate which is a phosphate group-containing reactive monomer as a reactive monomer, fumaric acid, benzoyl peroxide (BPO) as a polymerization initiator ), Methanol, tetrahydrofuran, and acetone as organic solvents were blended as shown in Table 1 to prepare curable resin compositions of Examples 1 to 3. These were impregnated with 23 g / m ² of melamine resin decorative board overlay base paper at a resin rate of 200% (resin content 46 g / m ² ) and dried to prepare adhesive sheets of Examples 1 to 4, and the test conditions were When the adhesive strength measurement test was performed by the described method, the results shown in Tables 2 and 3 were obtained.
Examples 4-5
Denkabutyral # 5000-D as a crystalline oligomer prepared in Synthesis Example 2 and polyvinyl acetal (manufactured by Denki Kagaku Kogyo Co., Ltd., product name, acetalization degree 81 wt%, polymerization degree 2100, acetal composition is an acid-modified polyvinylacetate derived from acetaldehyde Acetal, Tg 110 ° C.), Denkabutyral # 6000-EP (manufactured by Denki Kagaku Kogyo Co., Ltd., product name, acetalization degree 73 wt%, polymerization degree 2400, acetal composition is acetaldehyde and butyraldehyde mixed acetal, acid-modified polyvinyl acetal, Tg 85 ° C. ), Benzoyl peroxide (BPO) as a polymerization initiator, methanol and acetone as organic solvents were blended as shown in Table 1, and curable resin compositions of Examples 4 to 5 were prepared. These were impregnated with 23 g / m ² of melamine resin decorative board overlay base paper at a resin rate of 200% (resin content 46 g / m ² ) and dried to prepare adhesive sheets of Examples 4 to 5 and tested. When the adhesive strength measurement test was performed by the described method, the results shown in Tables 2 and 3 were obtained.

Comparative Example Crystalline oligomer (3) prepared in Synthesis Example 3, ESREC BM2 as a polyvinyl acetal, 2-methacryloyloxyethyl acid phosphate, a fumaric acid, a blocked isocyanate, which is a reactive monomer containing a phosphate group as a reactive monomer (Product name Sumidur BL3175, manufactured by Sumika Bayer Urethane Co., Ltd.), benzoyl peroxide (BPO) as a polymerization initiator, methanol and tetrahydrofuran as organic solvents are blended as shown in Table 1, and resin compositions of Comparative Examples 1 and 2 A product was prepared. These were impregnated into 23 g / m ² of the above-mentioned base melamine resin laminate base paper under a 200% resin condition (resin content 46 g / m ² ) and dried to prepare adhesive sheets of Comparative Examples 1 and 2. Resin of Comparative Example 3 containing the crystalline oligomer (2) prepared in Synthesis Example 2, ESREC BM2 as a polyvinyl acetal, benzoyl peroxide (BPO) as a polymerization initiator, methanol and acetone as organic solvents as shown in Table 1. A composition was prepared. This was impregnated into 23 g / m ² overlay base paper for melamine resin decorative board under the condition of a resin rate of 200% (resin content 46 g / m ² ) and dried to prepare an adhesive sheet of Comparative Example 3. As Comparative Example 4, a phenol formaldehyde resin (resole type: solid content: 50%) and a resin composition of Comparative Example 4 prepared by using the ESREC BM2 as polyvinyl butyral were used as a 23 g / m ² melamine resin decorative board overlay base paper. When an adhesive sheet of Comparative Example 4 was prepared by impregnation and drying under the condition of a resin rate of 200% (resin content 46 g / m ² ), the adhesive strength measurement test was performed by the method described in the test conditions. The result was 3. As a reference, Table 4 shows the results when the pressing time was shortened to 5 minutes.

Hippopotamus x Hippopotamus Press temperature 140 ℃
Pressure 2.5MPa
Breath time 12 minutes: Adhesive strength unit N / mm ²
FF unit μg / m ²

Hippopotamus x Aluminum plate Press temperature 140 ℃
Pressure 2.5MPa
Breath time 15 minutes: Adhesive strength unit N / mm ²
FF unit μg / m ²

Hippopotamus x Hippopotamus Press temperature 140 ℃
Pressure 2.5MPa
Breath time 5 minutes: Adhesive strength unit N / mm ²
FF unit μg / m ²

Test method 1. Tensile test piece (bonding area 13mm x 25mm)
1. Cover material with thickness of 1.0 mm and width of 25 mm. Cover material with thickness of 1.0 mm and width of 25 mm and aluminum plate with thickness of 0.3 mm and width of 25 mm. Test conditions Normal: Tensile shear test without treatment (tensile speed 50 mm / min)
Heat resistance test: A tensile shear test (a tensile speed of 50 mm / min) is performed immediately after being left in a dryer at 100 ° C. for 24 hours.

Water resistance test: After boiling at 100 ° C. for 4 hours, dried at 60 ° C. for 20 hours, further boiled at 100 ° C. for 4 hours, and then subjected to a tensile shear test (a tensile speed of 50 mm / min).
3. FF: Method for measuring formaldehyde emission Measured according to JIS A1901-2003 small chamber test.
4). FP: Method for measuring free phenol After boiling the adhesive with 200 ml of water for 1 hour, the boiling water was measured according to JIS K0102-1998 factory drainage test method.

  Since the curable resin composition according to the present invention contains a crystalline oligomer mixture that is solid at room temperature having a polymerization curable unsaturated bond and a block isocyanato group, adhesion equal to or higher than that of a phenol-formaldehyde resin, It has heat resistance, water resistance and good handling properties. Moreover, it does not contain formaldehyde, which is a causative substance of sick house syndrome. Furthermore, high adhesion, heat resistance, and water resistance can be obtained without separately adding a blocked isocyanate compound having no polymerization curable unsaturated bond. Further, as the polyvinyl acetal, it is preferable to use acid-modified polyvinyl acetal to obtain higher adhesion, heat resistance and water resistance.

  Therefore, a metal foil laminate, a metal foil laminate decorative plate, a plastic foil, a plastic sheet, a laminate, or an adhesive that bonds a wood-based material, which is a laminate of a copper foil and a resin laminate used in printed printed wiring boards, It can be used for various purposes such as a binder for bonding glass fibers and the like. These resin processed products can be used in various fields such as building materials, furniture materials, decorative materials, electronic materials, vehicle materials, aircraft materials, and ship materials.

  Furthermore, the curable resin composition of the present invention is an addition reaction curing system, and obtains the desired performance by curing in a short time compared to a condensation curing system such as a phenol-formaldehyde resin and an amino-formaldehyde resin. Can do.

Claims (5)

A crystalline oligomer obtained by reacting a compound having a hydroxyl group and a polymerizable unsaturated bond, a compound having an isocyanate group, and an isocyanate group blocking agent, and having a polymerizable unsaturated bond and a blocked isocyanate group. 2. The compound according to claim 1, wherein the compound having a hydroxyl group and a polymerizable unsaturated bond is at least one selected from the group consisting of (meth) acrylate having a primary hydroxyl group, allyl alcohol, allyl ether, and vinyl ether. Crystalline oligomer. A curable resin composition comprising the crystalline oligomer and polyvinyl acetal. The curable resin composition according to claim 3, wherein the polyvinyl acetal is an acid-modified polyvinyl acetal. An adhesive sheet obtained by impregnating or coating a substrate with the curable resin composition.