JP2660885B2 - Heat-sensitive adhesive composition and adhesive sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive adhesive composition and an adhesive sheet, and more particularly to a heat-sensitive adhesive which has heat resistance and is used for heat-resistant laminates such as flexible printed circuit boards. The present invention relates to a possible heat-sensitive adhesive composition and an adhesive sheet formed thereby.

[0002]

2. Description of the Related Art In recent years, electronic equipment has been reduced in size and weight, the density of circuits has been increased, and the like, and a flexible printed circuit board (hereinafter, referred to as an "FPC board") has been widely used. This FPC board is basically made of a film of a heat-resistant resin such as a polyester resin, a polyimide resin, a polyamide-imide resin, or a polyparabanic acid resin, or a cloth made of fibers of these resins. , And a conductive metal foil such as copper or aluminum is laminated thereon to provide a metal-clad laminate. In order to laminate or fix such an FPC board to another board, a non-support type adhesive sheet is used. Alternatively, in the final stage of the printed wiring processing step of the FPC board, in order to prevent the metal conductor foil pattern formed in the preceding etching step from oxidation or the like, a sheet of a material substantially similar to the base material of the FPC board is formed. A coverlay sheet coated with an adhesive is used.

[0003]

However, these include:
There was a problem that the stability (storability) of the applied adhesive was poor. That is, applied to the heat-resistant film,
Alternatively, the heat-sensitive adhesive processed into the non-support type adhesive sheet has a problem that the functional group causes a cross-linking reaction with time and the adhesive strength is reduced. And the above F
The PC board is generally subjected to a solder bath treatment after the printed wiring processing step. However, if the adhesive strength of the laminated board or the cover lay sheet is reduced, the PC board is sufficiently adapted to the adherend during heating and pressing. In some cases, problems such as foaming, blistering, and peeling occur in the solder bath treatment. Therefore, development of a heat-sensitive adhesive composition that solves these problems has been desired.

[0004]

Means for Solving the Problems In view of the above-mentioned circumstances, the present inventors have conducted intensive studies to obtain an adhesive having no change over time and excellent heat-sensitive adhesiveness. The present inventors have found that the object can be achieved by using a heat-sensitive adhesive composition and suppressing the reaction of the functional group of the composition with a specific compound, and completed the present invention.

That is, the present invention provides a heat-sensitive composition comprising 25 to 100 parts by weight of a phenol resin, 5 to 50 parts by weight of an epoxy resin, and 1 to 20 parts by weight of a reaction inhibitor based on 100 parts by weight of an acrylic polymer having a carboxyl group. The present invention provides a mold adhesive composition.

The carboxyl group-containing acrylic polymer used in the heat-sensitive adhesive composition of the present invention basically comprises an acrylic monomer and a small amount of a monomer having a carboxyl group. Any one may be used as long as it is prepared by ordinary solution polymerization, emulsion polymerization, suspension polymerization, or bulk polymerization.

Preferred examples of the acrylic polymer include the following three components: (a) an alkyl group having 1 to 1 carbon atoms;
And acrylic polymers containing (b) acrylonitrile or methacrylonitrile and (c) a carboxyl group-containing copolymerizable vinyl monomer.

Among them, (meth) acrylate (meth) acrylate having an alkyl group having 1 to 12 carbon atoms imparts flexibility to the heat-sensitive adhesive composition. Are methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, isopentyl (meth) acrylate, n-hexyl (meth) acrylate,
Isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, and the like. And one or more of these are used. These (a)
The mixing ratio of the components is 40 to 79 in the acrylic polymer.
% By weight (hereinafter simply referred to as “%”). If the amount is less than 40%, the flexibility may be impaired. On the other hand, if the amount is more than 79%, protrusion may occur at the time of thermocompression bonding.

The component (b), acrylonitrile or methacrylonitrile, imparts heat resistance, adhesiveness and chemical resistance, and is preferably blended in an acrylic polymer in an amount of 20 to 50%. This is 20%
Below, heat resistance is inferior, and when it is 50% or more, flexibility may be impaired, which is not preferable.

Further, the carboxyl group-containing copolymerizable vinyl monomer of the component (c) imparts adhesiveness and serves as a crosslinking point upon heating. Specific compounds include acrylic acid, Methacrylic acid, crotonic acid,
Maleic acid, fumaric acid, itaconic acid and the like can be mentioned.
The amount of the component (c) in the acrylic polymer is 1
When the blending amount is 1% or less, the crosslinking effect is small. When the blending amount is 10% or more, too much crosslinking is caused and the adhesion to the adherend is poor, and bubbles or swelling during heating curing treatment or solder bath treatment is caused. It is not preferable because it may cause a problem.

On the other hand, the phenolic resin used in the heat-sensitive adhesive composition of the present invention imparts thermosetting properties, heat resistance, adhesive properties, and the like. Preferred examples thereof include bisphenol A and p-type. Examples thereof include resol-type phenol resins prepared from alkylphenols such as t-butylphenol, octylphenol, p-cumylphenol, p-phenylphenol, cresol and the like as raw materials.
The phenolic resin is preferably blended in an amount of 25 to 100 parts by weight based on 100 parts by weight of the acrylic polymer.
When the blending amount of the phenolic resin is 25 parts or less, the thermosetting property may be insufficient, and when the blending amount is 100 parts or more, the adhesive strength may be reduced, and neither is preferable.

Further, the epoxy resin used in the present invention contributes to the thermosetting adhesive composition in thermosetting properties and adhesive strength, and is 5 to 50 parts by weight based on 100 parts by weight of the acrylic polymer.
It is preferable to mix by weight. When the amount of the epoxy resin is less than 5 parts by weight, the thermosetting property and heat resistance are insufficient, and when the amount is more than 50 parts by weight, the resin is excessively cross-linked and poorly adheres to the adherend. Alternatively, it is not preferable because it may cause bubbles or blisters during the solder bath treatment. In addition, as a preferable epoxy resin, it contains two or more epoxy groups, and the epoxy equivalent is 150-10.
00, specifically, bisphenol A type epoxy resin, novolak type epoxy resin, aliphatic epoxy resin and the like. Epoxy equivalent is 150-10
In the case of using an epoxy equivalent of 00 or less, excellent adhesive strength is obtained, but in the case of using an epoxy equivalent of 150 or less, the adhesive strength is low, and when the epoxy equivalent of 1000 or more is used, the reactivity is low. Any of these is not preferred because of insufficient thermosetting properties. Further, an epoxy-modified phenol resin in which a phenol resin and an epoxy resin satisfying the above conditions are combined may be used.

The reaction inhibitor used in the present invention has a function of suppressing the crosslinking reaction of the functional group present in the heat-sensitive adhesive composition at room temperature and exhibiting thermosetting without inhibiting the crosslinking reaction when heated. Is to be granted. As the reaction inhibitor, for example, an organic acid anhydride that suppresses a reaction between an epoxy group and a carboxyl group, an aromatic amine that suppresses a reaction between a hydroxyl group and a carboxyl group, and the like are used. Specific organic acid anhydrides include phthalic anhydride, maleic anhydride, hexahydrophthalic anhydride, pyromellitic anhydride,
Examples of aromatic amines include trimellitic anhydride, dodecyl succinic anhydride, and the like. Rangeamine, 4,4'-diaminodiphenylmethane, 4,
Examples thereof include 4′-diaminodiphenyl ether and aromatic amines obtained by modifying these. This reaction inhibitor is used in an amount of 1 to 100 parts by weight of the acrylic polymer.
It is preferable to add 20 parts by weight. If the amount of the reaction inhibitor is less than 1 part by weight, a sufficient effect cannot be obtained.
Even if it is added in an amount of 0 part by weight or more, the effect is hardly improved, and conversely, the adhesive strength is lowered, which is not preferable.

The heat-sensitive adhesive composition of the present invention may be prepared by mixing and mixing the above-mentioned components according to a conventional method, and if necessary, further known components may be added. The heat-sensitive adhesive composition thus obtained is applied to a heat-resistant film,
After drying, a single-sided adhesive sheet or the like can be obtained by attaching a separator. Further, a non-support type adhesive sheet can be obtained by applying and drying the heat-sensitive adhesive composition of the present invention on a separator, and then attaching another separator thereto.

Specifically, the following products are exemplified as products using the heat-sensitive adhesive composition of the present invention. On the separator, phenolic resin 25 to 100 parts by weight of the carboxyl group-containing acrylic polymer is used.
100 parts by weight, 5 to 50 parts by weight of an epoxy resin, 1 to 20 parts by weight of a reaction inhibitor, a heat-sensitive adhesive composition is applied, dried, and then a non-support is obtained by attaching another separator. Mold adhesive sheet. 100 parts by weight of a carboxyl group-containing acrylic polymer on a double-sided separator, phenolic resin 25 to 25 parts by weight
A non-supporting adhesive sheet in which a heat-sensitive adhesive composition comprising 100 parts by weight, 5 to 50 parts by weight of an epoxy resin, and 1 to 20 parts by weight of a reaction inhibitor is applied, dried, and then rolled. Nonwoven fabric or plastic film as core material,
Acrylic polymer containing carboxyl group on both sides 100
25-100 parts by weight of a phenolic resin, based on parts by weight,
A double-sided adhesive tape obtained by applying and drying a heat-sensitive adhesive composition comprising 5 to 50 parts by weight of an epoxy resin and 1 to 20 parts by weight of a reaction inhibitor, and attaching a separator to both sides or one side.

[0016]

An adhesive having excellent properties can be obtained by using a combination of the above-mentioned carboxyl group-containing acrylic polymer, phenol resin and epoxy resin as the heat-sensitive adhesive composition. However, if this is left in the state of being applied to a film or in the state of a transfer sheet, the crosslinking reaction proceeds with time, and the adhesive strength is reduced. As a result,
Foaming and blistering sometimes occurred during processing. The reaction inhibitor used in the present invention functions to suppress the reaction of the functional group of the heat-sensitive adhesive composition and to prevent the progress of the crosslinking reaction. The reaction inhibitor loses the function of hindering the progress of the crosslinking reaction at the temperature at which heat-sensitive bonding or heat curing is performed, so that the thermosetting property is not reduced. By such an action mechanism, the heat-sensitive adhesive composition of the present invention can achieve both the storage stability at room temperature and the excellent thermosetting property during heat-sensitive adhesion and heat curing.

[0017]

As described above, the heat-sensitive adhesive composition of the present invention has the preservability at room temperature and the excellent thermosetting property at the time of heat-sensitive adhesion and heat curing as described above. Like a non-support type adhesive sheet, it can be very advantageously used as a heat-sensitive adhesive which requires a certain period of storage.

[0018]

EXAMPLES Next, the present invention will be described in more detail with reference to Production Examples, Examples and Comparative Examples. Note that these examples and the like do not limit the present invention at all. Production Example 1 Preparation of Acrylic Polymer A-1: 200 g of ion-exchanged water was placed in a reaction vessel equipped with a stirrer, a condenser, a thermometer, and a nitrogen inlet tube, and poval (Kuraray PVA 21) was added.
1.0 g of 7) was dissolved. Acrylic acid n in another container
-Butyl (BA) 65 g, acrylonitrile (AN) 3
A solution prepared by sufficiently stirring and dissolving 0.8 g of lauryl peroxide (LPO) in 5 g of acrylic acid (AA) and 5 g of acrylic acid (AA) was placed in a reaction vessel, and the reaction was carried out for 4 hours while maintaining the internal temperature at 70 ° C. After cooling, the mixture was allowed to stand, and the precipitate was dried and dissolved in ethyl acetate to adjust the nonvolatile content to 30%. The weight average molecular weight measured by GPC was 420,000.

Production Example 2 In the same manner as in Production Example 1, BA / AN / AA was 85/1.
A 0/5 compound (acrylic polymer A-2) was prepared. Its weight average molecular weight was 580,000.

Production Example 3 In the same manner as in Production Example 1, the ratio of BA / AN / AA was 85/3.
A blend (acrylic polymer A-3) having a ratio of 5/1 was prepared. Its weight average molecular weight was 460,000.

Example 1 100 parts of the acrylic polymer A-1 obtained in Production Example 1 was mixed with a phenol resin (CKM1634; resol type, manufactured by Showa Polymer Co., Ltd.) at a solid content weight ratio (the same applies hereinafter) of 30.
And 15 parts of an epoxy resin (Epicoat # 1001; bisphenol A type epoxy equivalent 450-500, manufactured by Yuka Shell Epoxy Co., Ltd.) and 8 parts of phthalic anhydride, and these were mixed in a conventional manner to obtain a heat-sensitive adhesive. A composition was obtained (Adhesive 1 of the present invention).

Example 2 A heat-sensitive adhesive composition was obtained in the same manner as in Example 1 except that 8 parts of phthalic anhydride as a reaction inhibitor was replaced with 4 parts of m-phenylenediamine and 4 parts of phthalic anhydride. (Adhesive 2 of the present invention).

EXAMPLE 3 100 parts of the acrylic polymer A-1 obtained in Production Example 1, 25 parts of a phenol resin (PL-2208; resol type, manufactured by Gunei Chemical Co., Ltd.) and an epoxy resin (Epicoat # 1)
003; bisphenol A type epoxy equivalent 670 to 7
20 parts of Yuka Shell Epoxy Co., Ltd.) and 8 parts of phthalic anhydride were added and mixed according to a conventional method to obtain a heat-sensitive adhesive composition (Adhesive 3 of the present invention).

Example 4 A heat-sensitive adhesive composition was obtained in the same manner as in Example 1 except that 8 parts of phthalic anhydride as a reaction inhibitor was replaced with 8 parts of m-xylenediamine (Adhesive 4 of the present invention). ).

Comparative Example 1 A heat-sensitive adhesive composition having the same composition as in Example 1 except for phthalic anhydride was obtained (Comparative Adhesive 1).

Comparative Example 2 An epoxy resin (Epicoat # 1001) was added to 100 parts of the acrylic polymer A-1 obtained in Production Example 1, and the mixture was mixed according to a conventional method to obtain a heat-sensitive adhesive composition. (Comparative adhesive 2).

Comparative Example 3 To 100 parts of the acrylic polymer A-1 obtained in Production Example 1, 30 parts of a phenol resin (CKM1634) was added.
This was mixed according to a conventional method to obtain a heat-sensitive adhesive composition (Comparative Adhesive 3).

Comparative Example 4 30 parts of a phenol resin (CKM1634) and 30 parts of an epoxy resin (Epicoat 1007; bisphenol A type; epoxy equivalent: 1750-2200 oily shell epoxy) were used for 100 parts of the acrylic polymer A-1 obtained in Production Example 1. 15 parts and 8 parts of phthalic anhydride were added and mixed according to a conventional method to obtain a heat-sensitive adhesive composition (Comparative Adhesive 4).

Comparative Example 5 100 parts of the acrylic polymer A-1 obtained in Production Example 1 was added to a phenol resin (CKM2400; novolak type).
30 parts of Showa Polymer Co., Ltd.), 15 parts of epoxy resin (Epicoat # 1001) and 8 parts of phthalic anhydride were added,
This was mixed according to a conventional method to obtain a heat-sensitive adhesive composition (Comparative Adhesive 5).

Comparative Example 6 To 100 parts of the acrylic polymer A-2 obtained in Production Example 2, 30 parts of a phenol resin (CKM1634), 15 parts of an epoxy resin (Epicoat # 1001) and 8 parts of phthalic anhydride were added. Was mixed in a conventional manner to obtain a heat-sensitive adhesive composition (Comparative Adhesive 6).

Comparative Example 7 To 100 parts of the acrylic polymer A-3 obtained in Production Example 3, 30 parts of a phenol resin (CKM1634) and 15 parts of an epoxy resin (Epicoat # 1001) were added, and mixed in a conventional manner. Thus, a heat-sensitive adhesive composition was obtained (Comparative Adhesive 7).

Test Example 1 The heat-sensitive adhesive compositions prepared in Examples and Comparative Examples were dried on a separator to a thickness of 4%.
It was applied so as to have a thickness of 0 μm, dried at 100 ° C. for 3 minutes, and then another separator was applied thereto to produce a non-support type adhesive sheet. After peeling off the separator of the adhesive sheet, the adhesive sheet was sandwiched between a 90 μm-thick FPC board and a 6 mm-thick glass epoxy plate, and heated and pressed at 150 ° C. for 2 minutes at a pressure of 5 kg / cm ² . The laminate is further cooled to 170 ° C. under normal pressure.
For 20 minutes.

With respect to the sample thus prepared,
The appearance after curing was observed, and the adhesive strength (peeling strength) and solder heat resistance according to JIS C6481 were examined.
Table 1 shows the results.

[0034]

Test Example 2 The heat-sensitive adhesive compositions prepared in Examples 1 and 2 and Comparative Example 1 were stored at room temperature for 3 months, and then heat-pressed in the same manner as in Example 1, The adhesive strength and solder heat resistance were examined. Table 2 shows the results.

[0036]

As is evident from the results, the adhesive strength of the comparative adhesive decreases after storage for a long period of time, and the heat resistance also decreases. Good.

Test Example 3 The heat-sensitive adhesive compositions prepared in Example 1 and Comparative Example 5 were stored at 40 ° C. for 2 weeks, and then heated and pressed in the same manner as in Example 1, and the appearance after heating and curing. , Adhesive strength and solder heat resistance were examined. Table 3 shows the results.

[0039]

As is apparent from the results, the adhesive of the comparative example shows a decrease in adhesive strength after storage under heating, and also a decrease in heat resistance. Is also good. that's all

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical indication location C09J 163/00 JFP C09J 163/00 JFP (72) Inventor Akira Nishii 130 Kamihirose Mukaida, Sayama City, Saitama Prefecture. Soken Kagaku Co., Ltd. (72) Inventor Shuji Okamoto 130 Kamihirose Mukata, Sayama City, Saitama Prefecture Soken Chemical Co., Ltd. (72) Inventor Yuji Ikeda 130 Kamihirose Mukada, Sayama City, Saitama Prefecture Soken Chemical Co., Ltd. (56) Reference Document JP-A-3-255186 (JP, A) JP-A-2-212574 (JP, A)

Claims (6)

(57) [Claims] 1. The following three components: (a) at least one kind of (meth) acrylate having an alkyl group having 1 to 12 carbon atoms, 40 to 79 parts by weight, and (b) acrylonitrile or methacrylonitrile, 20 to 50 parts by weight. (C) Carboxyl group-containing acrylic polymer 10 containing 1 to 10 parts by weight of carboxyl group-containing copolymerizable vinyl monomer
Resol type phenolic resin 25-1 based on 0 parts by weight
00 parts by weight, having two or more epoxy groups, epoxy equivalent
There epoxy resin 5 to 50 parts by weight of 150 to 1000, organic
A heat-sensitive adhesive composition comprising 1 to 20 parts by weight of a reaction inhibitor selected from the group consisting of an acid anhydride and an aromatic amine . 2. The heat-sensitive adhesive composition according to claim 1, wherein the reaction inhibitor is one or more aromatic amines. 3. A heat-resistant film having the following three components: (a) at least one kind of (meth) acrylate having an alkyl group having 1 to 12 carbon atoms, 40 to 79 parts by weight, and (b) acrylonitrile or methacrylic acid. Acrylonitrile 20 to 50 parts by weight (c) Carboxyl group-containing acrylic polymer 10 containing 1 to 10 parts by weight of a carboxyl group-containing copolymerizable vinyl monomer 10
Resol type phenolic resin 25-1 based on 0 parts by weight
00 parts by weight, 5 to 50 parts by weight of an epoxy resin having two or more epoxy groups and an epoxy equivalent of 150 to 1000, 1 to 20 parts by weight of a reaction inhibitor selected from the group consisting of organic acid anhydrides and aromatic amines A single-sided adhesive sheet formed by applying a heat-sensitive adhesive composition comprising a blended part. 4. On a separator, the following three components: (a) at least one kind of (meth) acrylate having an alkyl group having 1 to 12 carbon atoms 40 to 79 parts by weight (b) acrylonitrile or methacrylonitrile 20 (C) a carboxyl group-containing acrylic polymer 10 containing 1 to 10 parts by weight of (c) a carboxyl group-containing copolymerizable vinyl monomer 10
Resol type phenolic resin 25-1 based on 0 parts by weight
00 parts by weight, 5 to 50 parts by weight of an epoxy resin having an epoxy equivalent of 150 to 1000 having two or more epoxy groups, 1 to 20 parts by weight of a reaction inhibitor selected from the group consisting of organic acid anhydrides and aromatic amines A non-support type adhesive sheet obtained by applying and drying a heat-sensitive adhesive composition comprising the above components, and further applying another separator thereto. 5. A double-sided separator having the following three components: (a) at least one kind of (meth) acrylate having an alkyl group having 1 to 12 carbon atoms, 40 to 79 parts by weight, (b) acrylonitrile or methacrylonitrile 20 to 50 parts by weight (c) a carboxyl group-containing acrylic polymer 10 containing 1 to 10 parts by weight of a carboxyl group-containing copolymerizable vinyl monomer 10
Resol type phenolic resin 25-1 based on 0 parts by weight
00 parts by weight, 5 to 50 parts by weight of an epoxy resin having two or more epoxy groups and an epoxy equivalent of 150 to 1000, 1 to 20 parts by weight of a reaction inhibitor selected from the group consisting of organic acid anhydrides and aromatic amines Non-support type adhesive sheet obtained by applying and drying a pressure-sensitive adhesive composition comprising a plurality of parts, and then forming a roll. 6. A non-woven fabric or a plastic film as a core material, and the following three components on both sides: (a) at least one kind of (meth) acrylate having an alkyl group having 1 to 12 carbon atoms, 40 to 79 parts by weight ( b) acrylonitrile or methacrylonitrile 20 to 50 parts by weight (c) carboxyl group-containing acrylic polymer 10 containing 1 to 10 parts by weight of a carboxyl group-containing copolymerizable vinyl monomer 10
Resol type phenolic resin 25-1 based on 0 parts by weight
00 parts by weight, 5 to 50 parts by weight of an epoxy resin having two or more epoxy groups and an epoxy equivalent of 150 to 1000, 1 to 20 parts by weight of a reaction inhibitor selected from the group consisting of organic acid anhydrides and aromatic amines A double-sided adhesive tape obtained by applying and drying a pressure-sensitive adhesive composition prepared by blending parts, and attaching a separator to both sides or one side.