JPH0830178B2 - Adhesive composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to an adhesive composition, and more particularly, to improvement of adhesive performance due to a crosslinked structure of an acrylic adhesive composition.

[Outline of Invention]

The present invention provides a cross-linking function by mixing a peroxy compound having a double bond in a copolymer mainly composed of an acrylic ester so that a peroxy group of the compound is present, thereby providing a mixing operation. Is unnecessary and
At the same time, it aims to improve cohesive strength and adhesive performance.

[Conventional technology]

Generally, an acrylic adhesive or pressure-sensitive adhesive is a unit amount of a soft acrylic ester that gives tackiness and a reactive group such as a carboxyl group, an amino group, a hydroxyl group, or an epoxy group for improving cross-linking or adhesiveness. It is synthesized by copolymerizing the body.

In this case, in order to increase the cohesive force of the copolymer, it is necessary to add melamine, isocyanate, an organometallic compound or the like as a cross-linking agent to form a cross-linking structure during coating and drying. The formation of this crosslinked structure contributes to an increase in the molecular weight of the polymer, that is, an increase in the cohesive force which is an important factor of the adhesive.

Conventionally, the above-mentioned cross-linking agent is generally added as an external cross-linking agent. Therefore, this acrylic adhesive (adhesive) is put to practical use as a two-component mixed adhesive of the above-mentioned copolymer and cross-linking agent. Has been done.

[Problems to be solved by the invention]

However, the above-mentioned two-liquid mixed type adhesive requires a mixing operation for imparting cross-linking performance to the polymer, and its handling is complicated.

In addition, the above-mentioned two-component mixed adhesive has a problem in that the stability of the solution and the stability of the product are unstable due to the difference in reactivity of the external crosslinking agent to be added.

Therefore, the present invention has been proposed in order to eliminate the drawbacks of the conventional ones, and directly imparts a crosslinking function to eliminate the need for a mixing operation, and an adhesive composition having excellent cohesive force and adhesive performance. The purpose is to provide things.

[Means for solving problems]

The present inventors have developed an acrylic adhesive having a cross-linking function, and as a result of extensive research over a long period of time, a peroxy compound having a double bond as a monomer imparting a cross-linking function is useful. It was found that by introducing the peroxy groups of the above into the acrylic copolymer composition and decomposing the peroxy groups by heating or the like to form a crosslinked structure, it effectively acts on the heat resistance and displacement prevention of the copolymer. Came to get.

The present invention has been completed on the basis of such findings, and the general formula (Wherein R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents an alkyl group having 1 to 18 carbon atoms), relative to 100 parts by weight of a monomer mainly composed of an acrylic ester (A) represented by Reactive unsaturated monomer (B) 0 which is copolymerizable with the acrylic ester (A) and has at least one group of hydroxyl group, carboxyl group, epoxy group, amino group and derivative, and acid anhydride ~ 29 parts by weight, and general formula (In the formula, R ₃ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, R ₄ and R ₅ each represent an alkyl group having 1 to 4 carbon atoms, R ₆ represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms. Group or a cycloalkyl group having 5 to 7 carbon atoms, and n represents an integer of 0 to 4) and having a double bond (C) 0.5.
˜15 parts by weight, and the total amount of the reactive monomer (B) and the peroxy compound (C) is 0.5 to 30 parts by weight with respect to 100 parts by weight of the acrylic ester (A). The present invention is characterized in that it is a polymer polymerized so that the peroxy group of the peroxy compound (C) is present, and the present invention further provides 100 parts by weight of the polymer (I) constituting this adhesive composition. On the other hand, unlike the acrylic ester (A), the reactive unsaturated monomer (B) and the polymer (I), an improving monomer (D) having an unsaturated bond and copolymerizable with each other. And a polymer (II) obtained from at least one monomer selected from the above.

That is, in the present invention, an acrylic ester (A) is mainly used, and a reactive unsaturated monomer (B) and a peroxy compound (C) having a double bond are copolymerized with the acrylic ester as required. This is the adhesive composition.

Here, the composition of the reactive unsaturated monomer (B) and the peroxy compound (C) is such that the total amount thereof is in the range of 0.5 to 30 parts by weight with respect to 100 parts by weight of the acrylic ester (A). And the reactive unsaturated monomer (B) is added in an amount of 0 to 29 parts by weight, and the peroxy compound (C) is added in an amount of 0.5 to 15 parts by weight. When the monomer (B) is not added, it is preferable to copolymerize the peroxy compound (C) in the range of 2.0 to 15 parts by weight with respect to 100 parts by weight of the acrylic ester (A). When the reactive unsaturated monomer (B) is copolymerized, 10 parts by weight of the peroxy compound is added to 100 parts by weight of the total amount of the acrylic ester and the reactive unsaturated monomer. Copolymerization is preferable in the following range.

The acrylic ester (A) which is the main component of the adhesive composition has the general formula (In the formula, R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents an alkyl group having 1 to 18 carbon atoms.) An acrylic ester or a methacrylic ester represented by: , Ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, octadecyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, etc. . When it is necessary to give tackiness, the carbon number of R ₂ is 3
-10 acrylates are useful.

In addition, the above-mentioned reactive unsaturated monomer (B) is
Hydroxyl group-OH, carboxyl group-COOH, epoxy group A monomer having a double bond and at least one reactive group such as acid anhydride, amino group-NH ₂ and its derivative, and examples thereof include acrylic acid, methacrylic acid, acrylamide, methacrylamide, itaconic acid, Fumaric acid, N-methylolacrylamide, N-methylolmethacrylamide, N-methylolbutoxyacrylamide, N-methylolbutoxymethacrylate, glycidyl methacrylate, glycidyl acrylate, acrylic glycidyl ether, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate , 2-Hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, maleic anhydride, dimethylacrylamide, dimethylmethacrylamide, crotonic acid, allylglycidylmethacrylate, allylglycidylacryle Doo and the like. By introducing one or more of these, it is possible to improve the adhesiveness and increase the cohesive force.

Further, the peroxy compound (C) has the general formula (In the formula, R ₃ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, R ₄ and R ₅ each represent an alkyl group having 1 to 4 carbon atoms,
R ₆ represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms or a cycloalkyl group having 5 to 7 carbon atoms, and n represents an integer of 0 to 4. ) Is a compound having a peroxy group which is easily decomposed by heating or the like to form a crosslinked structure in the molecule, and a double bond for copolymerizing with other components. For example, t-butyl peroxy vinyl carbonate, t-hexyl peroxy vinyl carbonate, t-butyl peroxydiisopropenyl carbonate, t-butyl peroxy allyl carbonate, t-hexyl peroxy allyl carbonate, 1,1,3,3-tetra Examples include methylpropyl peroxyallyl carbonate, t-butyl peroxymethallyl carbonate, t-butyl peroxy (3-butenyl) carbonate and the like. By copolymerizing this peroxy compound with the acrylic ester,
A crosslinking function is imparted to the obtained copolymer. Further, if the above-mentioned reactive unsaturated monomer is copolymerized in this copolymer, it is possible to increase the cohesive force by an intramolecular or intermolecular reaction. The amount of reactive unsaturated monomers can be reduced.

Furthermore, in the adhesive composition of the present invention, in addition to the components of the above-mentioned monomers (A), (B) and (C), another copolymerizable monomer such as vinyl acetate can be added. , The copolymerizability is improved. Further, flame retardancy can be achieved by copolymerizing tribromophenyl acrylate.

Furthermore, a copolymerizable monomer having an unsaturated bond in the molecule may be used, for example, non-conjugated monomers such as vinyl acetate, vinyl propionate, aryl acetate, acrylonitrile, methacrylonitrile, and furfuryl. Acrylate, benzyl acrylate, benzyl methacrylate, phenyl methacrylate, styrene, methoxyethyl acrylate, ethoxyethyl acrylate, carbitol acrylate, methacrylic acid chloride, 2-chloroethyl methacrylate, 2-chloroethyl acrylate, vinyl imidazole, dimethylamino methacrylate, etc. You may add in the range which does not change the characteristic as an adhesive agent, for example, in the range which does not exceed 50 weight part with respect to 100 weight part of adhesive composition.

The above-mentioned monomers are mixed in a predetermined ratio, and the peroxy compound (C) is added in the presence of a polymerization initiator in a suitable solvent.
The adhesive composition of the present invention can be obtained by copolymerization under a conventional method under a polymerization condition at a relatively low temperature at which decomposition of the above is not caused. Examples of the polymerization initiator that can be used here include azo-based polymerization initiators and peroxy-based polymerization initiators, but sufficient polymerization reaction can be achieved even at a low temperature at which the peroxy compound blended as a copolymerization component does not decompose. You need to choose one that can proceed.
Preferred azo-based polymerization initiators are azobisisobutyronitrile, 2,2'-azobis- (2,4-dimethyl) valeronitrile, 1,1'-azobis- (cyclohexane) carbonitrile, etc. The system polymerization initiator is t
-Butyl peroxypivalate, t-butyl peroxy neodecanolate, t-butyl peroxyisobutyrate,
Examples include cumyl peroxy neodecanolate, t-butyl peroxy (2-ethylhexanoate) benzoyl peroxide, lauroyl peroxide and the like.

The polymerization method for obtaining the adhesive composition of the present invention is not limited to the solution polymerization method described above, and polymerization may be performed by a bulk polymerization method, an emulsion polymerization method, a suspension polymerization method, or the like. . The polymerization may be carried out by mixing all predetermined amounts of the respective monomers, but the polymerization may be started with 1 part of the monomers, and the remaining monomers may be added before or after the completion of the polymerization. Then, the polymerization may be carried out by a so-called division polymerization method or a multi-stage polymerization method.

[Action]

In the adhesive composition of the present invention, the peroxy compound having a double bond exhibits a function of decomposing by drying with heat or the like to form a crosslinked structure. Therefore, cohesive force and adhesive performance are secured without adding an external crosslinking agent.

Further, the acrylic ester serves as a base resin and has an action of imparting tackiness and the like. The reactive unsaturated monomer further increases cohesive force and improves adhesion by intramolecular or intermolecular reaction.

Furthermore, a modifying monomer that is different from these monomers has the effect of improving the physical and chemical properties of the adhesive, and the glass transition point and the like can be controlled by adding the modifying monomer. To be done.

〔Example〕

Hereinafter, specific examples of the present invention will be described.
The present invention is not limited to these examples.

Example 1. In a three-necked flask having a capacity of 1, 100 g of ethyl acetate, 0.1 g of azobisisobutyronitrile, 715 g of normal butyl acrylate as a polymerizable monomer (Pm), 13.5 g of methyl acrylate, 2.0 g of acrylic acid, t 2.0 g of -butylperoxyaryl carbonate was taken, and the inside of the reaction system equipped with a thermometer, a cooler, and a stirring blade was kept at 80 ° C, and the reaction was carried out for 4 hours while performing nitrogen gas replacement. The polymerization reaction took place in 0.5 to 2 hours, and the viscosity of the solution gradually increased.

Next, 0.1 g of azobisisobutyronitrile was added to ethyl acetate.
After adding the polymerization initiator dissolved in 5 g, 11.0 g of methyl methacrylate as a monomer (Pi) for addition was added dropwise, and the reaction was carried out for another 5 hours. Ethyl acetate after 5 hours
45.0 g was added and diluted to obtain a uniform copolymer solution. The above polymerization method is referred to as Pm / Pi.

The obtained copolymer solution was opaque and had a resin content of 38.6
%, The viscosity was 11800 (cps). The weight average molecular weight Mw was 518600 and the number average molecular weight Mn was 26400.

Comparative Example 1. 100 g of ethyl acetate, 0.1 g of azobisisobutyronitrile, and normal butyl acrylate as a polymerizable monomer (Pm)
Take 71.5g, methyl acrylate 13.5g, acrylic acid 2.0g,
A copolymer solution was obtained by the same polymerization method Pm / Pi as in Example 1.

The resulting copolymer solution was opaque and had a resin content of 39.0
%, The viscosity was 6150 (cps). The weight average molecular weight Mw was 310200 and the number average molecular weight Mn was 49200.

Example 2 In a three-necked flask having a capacity of 1, 110 g of ethyl acetate, 0.1 g of azobisisobutyronitrile, 10.0 g of normal butyl acrylate as a polymerizable monomer, 69.0 g of 2-ethylhexyl acrylate, 11.8 g of ethyl acrylate, and acrylic acid.
2.33 g, glycidyl methacrylate 0.27 g, t-butyl peroxyaryl carbonate 2.0 g, vinyl acetate 4.6 g were charged, and the temperature inside the reaction system equipped with a thermometer, a cooler, a nitrogen gas inlet, and a stirring blade was maintained at 80 ° C. The reaction was carried out while substituting nitrogen gas.

The polymerization reaction took place in 0.5 to 2 hours, and the viscosity of the solution gradually increased. The reaction was carried out for 8 hours and then diluted with ethyl acetate to complete the reaction and obtain a uniform copolymer solution. The above polymerization method and P _H.

The obtained copolymer solution was transparent and had a resin content of 28.6% and a viscosity of 745 (cps). The weight average molecular weight Mw is 4
It was 94,000.

Comparative Example 2. In a capacity / three-necked flask, 110 g of ethyl acetate, 0.1 g of azobisisobutyronitrile, 10.0 g of normal butyl acrylate as a polymerizable monomer, 69.0 g of 2-ethylhexyl acrylate, 11.8 g of ethyl acrylate, acrylic acid
2.33g, glycidyl methacrylate 0.27g, vinyl acetate 4.6g
It was charged, to obtain a copolymer solution according to the polymerization process P _H as in Example 2.

The obtained copolymer solution was transparent and had a resin content of 29.9% and a viscosity of 1820 (cps). The weight average molecular weight Mw is
It was 540000.

It was synthesized a copolymer solution according to the polymerization process P _H of the polymerization method Pm / Pi or Example 2 of the Examples 3-17 and Comparative Examples 3-14 Example 1.

The monomer blends and properties in each of the examples and comparative examples are shown in Tables I-1 and I-2.

 The abbreviations in the table indicate the following compounds.

n-BA: normal butyl acrylate 2EHA: 2-ethylhexyl acrylate EA: ethyl acrylate MA: methyl acrylate MMA: methyl methacrylate TBPA: tribromophenyl acrylate AA: acrylic acid GMA: glycidyl methacrylate HEMA: 2-hydroxyethyl acrylate N-MAM : N-methylol acrylamide MAHD: Maleic anhydride AMD: Acrylamide t-BPAC: t-Butylperoxyaryl carbonate VAc: Vinyl acetate BOEA: Butoxyethyl acrylate AIBN: Azobisisobutyronitrile LPO: Lauryl peroxide Next, the adhesive performance of the copolymers obtained in each of the above Examples and Comparative Examples was examined.

Sample preparation method Copolymer solutions obtained in Examples and Comparative Examples were uniformly applied on a release paper coated with a silicone release agent, and a uniform sample film having a weight of 40 ± 5 g / m ² on the silicone release paper. Was formed. The drying was performed first at 60 ° C. for 5 minutes and then at 150 ° C. for 5 minutes.

The sample film was used as sample (A). A 25 μm thick polyester film was laminated on this sample film, and the sample film after aging at 50 ° C. for 240 hours was used as a sample (B). Further, a sample film after aging for 240 hours at 40 ° C. and 90% relative humidity was used as a sample (C).

For each of these samples, the peel strength, cohesive strength, and the degree of increase in peel strength after aging for 10 minutes at 150 ° C were measured. The test method is as follows.

Test method (a) Peeling force: Each sample was cut into a piece with a width of 2 cm and a length of 20 cm, the release paper was peeled off, and a stainless steel plate (the surface was water-resistant abrasive paper # 280
After polishing with and cleaning with toluene, the solvent was removed. )
It was attached so that no bubbles or wrinkles would enter, and a rubber roller with a load of 2 kg was reciprocated once for pressure bonding. 1 hour after crimping
180 ° peeling was performed at a rate of 300 mm / min under the conditions of 20 ° C and 65% relative humidity, and the resistance when the sample film peeled from the stainless steel plate was obtained.

(B) Cohesive strength: A sample film measuring 2.5 cm in width and 7 cm in length is adhered to one end of a stainless plate having a width of 3 cm, a length of 5 cm and a thickness of 2 mm.
A 2.5 cm × 2.5 cm joint was formed on a stainless steel plate. In addition, the width of the sample film protruding from the stainless steel plate
A 2.5 cm × 5 cm length × 25 μm thick polyester film was lined and passed through a 2.5 kg load rubber roller once. Next, one end (non-adhesive part of the stainless steel plate) of the sample film was fixed to a dryer whose temperature was adjusted to 40 ° C., and a weight of 1 kg was hung on the backing part of the polyester film. With this, the time until the above-mentioned bonded portion was displaced and dropped, or the displacement (mm) of the bonded portion after 1 hour was measured.

(C) Peeling force after heat aging at 150 ° C. for 10 minutes: A test piece similar to the peeling force measurement in (a) above was prepared, and this test piece was heated at a temperature of 15
It was put in a dryer at 0 ° C., heat-aged for 10 minutes, taken out, and allowed to cool at room temperature for 1 hour. Then, the peeling force was measured under the same conditions as in (a).

The results are shown in Table II-I and Table II-2. In the table, AF
The one marked with indicates that interfacial failure from the adherend occurred, the one marked with CF indicates that interlaminar failure (cohesive failure) of the adhesive occurred, and MAF indicates unstable failure from the polyester film. Indicates that something has happened.

Furthermore, in order to investigate the stability of the copolymer solution in Example 2, Example, and Example 12, the initial viscosity, the viscosity after storage at 20 ° C. for 30 days, and the viscosity after storage at 40 ° C. for 30 days were measured. did. The viscosity was measured by adjusting the copolymer solution to 25 ± 1 ° C. and using a rotary viscometer. The results are shown in Table III.

From Table III, it can be seen that the copolymer solutions of the above-mentioned examples have very little increase in viscosity and are excellent in stability.

Next, in the adhesive composition of the present invention, changes in adhesive performance due to a crosslinking reaction based on thermal decomposition of the peroxy compound contained in the copolymer were examined. That is, the example
2, The copolymer solutions of Example 10 and Example 15 were dried under the conditions shown in Table IV, and their peeling force and cohesive force were measured. The results are shown in Table IV.

From the above experimental results, it is understood that when dried by heating at 150 ° C. or higher, the peroxy group is decomposed to form a crosslinked structure, and the cohesive force (resistance to deviation) increases. On the other hand, in the case of drying at 110 ° C, the crosslinking is insufficient and the cohesive force is reduced. That is, the decomposition of the peroxy group is insufficient.

〔The invention's effect〕

As is clear from the above description, in the adhesive composition of the present invention, since the peroxy compound having a non-conjugated double bond is copolymerized with the acrylic ester, the copolymer itself has a crosslinking function. It can be applied, and a crosslinked structure can be formed by heating and drying after coating, without requiring a mixing operation. Therefore, it is possible to provide an adhesive composition that is easy to handle and has excellent adhesive performance, cohesive force, stability, and the like.

In addition, by copolymerizing a reactive unsaturated monomer, if necessary, an intramolecular or intermolecular reaction can be induced to further improve cohesive force and adhesive performance.

Furthermore, in the second invention of the present invention, since the above-mentioned adhesive composition has a constitution in which a polymer having a monomer composition different from the composition constituting this adhesive composition is combined, The physical and chemical properties of the adhesive composition to be used can be improved, and for example, the copolymerizability can be improved, flame retardancy can be imparted, and the glass transition point can be controlled.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Pan Nagase 3-25-3 Hasune, Itabashi-ku, Tokyo Fujikura Kasei Co., Ltd. (72) Yoichi Hirayama 3-25 Hasune, Itabashi-ku, Tokyo Fujikura Kasei Within the corporation

Claims (1)

[Claims] 1. A general formula (In the formula, R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents an alkyl group having 1 to 18 carbon atoms.) In 100 parts by weight of a monomer mainly containing an acrylic ester (A) On the other hand, the above acrylic ester (A)
Copolymerizable with hydroxyl group, carboxyl group, epoxy group,
0 to 29 parts by weight of a reactive unsaturated monomer (B) having at least one group of an amino group and its derivative and an acid anhydride, and a general formula (In the formula, R ₃ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, R ₄ and R ₅ each represent an alkyl group having 1 to 4 carbon atoms, R ₆ represents a hydrogen atom, alkyl group having 1 to 12 carbon atoms. Group or a cycloalkyl group having 5 to 7 carbon atoms, n represents an integer of 0 to 4) and has a double bond.
The total amount of the reactive unsaturated monomer (B) and the peroxy compound (C) is 0.5 to 30 parts by weight with respect to 100 parts by weight of the acrylic ester (A). An adhesive composition characterized by being a polymer polymerized such that the peroxy group of the above-mentioned peroxy compound (C) is present.