JPS6381187A - Thermosetting adhesive sheet - Google Patents

Abstract

PURPOSE:To obtain an adhesive sheet suitable for bonding, having improved shelf stability at normal temperature, low fluidity, improved heat resistance, water-vapor resistance and chemical resistance, by molding a specific mixture of a thermosetting type epoxy resin composition and heating the mixture into a semicured state. CONSTITUTION:(A) A thermosetting type epoxy resin composition preferably comprising an epoxy resin and one or more curing agents selected from curing agents of amine type, polyamide type and imidazole type as essential components is blended with (B) a thermosetting type epoxymethacrylate resin composition which is not cured or slightly cured by heating at the curing temperature of the component A and cured by heating at >= the curing temperature. The blend is molded into a sheet or filmy state and heated to the curing temperature of the component A to give the aimed adhesive sheet in a semicured state. A thermosetting type epoxymethacrylate resin composition comprising an epoxymethacrylate resin of bisphenol type, novolak type or aliphatic type, a nonpolymerizable crosslinking agent and a radical polymerization initiator as essential components is preferable as the component B.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a thermosetting adhesive sheet used for bonding printed wiring boards to each other, or to bonding printed wiring boards to a base material, copper foil, etc. be.

[Prior Art] Conventionally, such thermosetting adhesive sheets have been produced by impregnating or coating a base material with a thermosetting resin composition mainly composed of epoxy resin, unsaturated polyester resin, etc. It is produced by forming it into a film and heating it at an appropriate temperature and time to bring it into a semi-cured state.

However, the above thermosetting adhesive sheet has the following drawbacks.

First, in order to bring the resin composition into the desired semi-cured state homogeneously and with good 1Q developability, it was necessary to strictly control manufacturing conditions such as heating temperature and time. Next, since the adhesive sheet is in a semi-cured state, the curing reaction of the unreacted resin proceeds gradually even at room temperature. Therefore, the storage stability of the adhesive sheet was extremely poor.

In addition, strict manufacturing conditions such as heating temperature and heating time,
As a method for obtaining an adhesive sheet having a uniform and stable semi-cured state without the need for controlling, JP-A-56-114691 discloses a TL female radiation-curable resin composition that is cured by irradiation with ionizing radiation. By impregnating a base material with a mixture with a thermosetting resin composition that does not cure with ionizing radiation, or forming it into a sheet or film, and irradiating it with ionizing radiation, an ionizing radiation curable resin composition can be prepared. Adhesive sheets that only harden objects have been proposed. By changing the mixing ratio of the ionizing radiation-curable resin composition and the heat-curable resin composition, the adhesive sheet made of this mixed resin composition can be uniformly and stably produced with the desired semi-cured state. I was able to do that. However, this adhesive sheet had the following serious problems.

First, it is not possible to remove the solvent from the resin set Itr, fs by irradiating it with ionizing radiation.
It must be a solvent-free resin composition. However, a solvent-free, low-viscosity ionizing radiation-curable resin composition or heat-curable resin composition that can be sufficiently impregnated into a base material such as glass cloth has not yet been developed.
In order to sufficiently impregnate a base material with these highly viscous resins 11 and 3, special equipment such as vacuum impregnation or super sweat wave impregnation is required. Furthermore, even if the viscosity of these resin compositions is lowered by adding reactive or non-reactive diluents, the cured products will
There are drawbacks such as significant deterioration in performance such as heat resistance and moisture resistance.

Further, the ionizing radiation applied to bring the material into a semi-cured state not only damages the base material but also causes serious harm to the human body of the worker. Additionally, unlike ordinary heating furnaces, equipment that irradiates with ionizing radiation is expensive and has drawbacks such as being extremely time-consuming to maintain and maintain.

Next, the adhesive sheets used in the above-mentioned industrial application fields have not only good adhesive strength but also low resin flowability when heated and pressed to prevent the resin from extruding onto the circuit-forming metal surface or the edge of the base material. is required. Conventional adhesive sheets have flexibility by adding a rubbery component to a thermosetting epoxy resin composition, thereby providing both low flowability and adhesive strength.

However, the adhesive sheet described in L has the following drawbacks.

That is, since a rubber-like component is added, there is a drawback that performance such as moisture resistance, heat resistance, chemical resistance, etc. is greatly reduced.

The present invention has been made to solve the problems of conventional adhesive sheets as described above, and its purpose is to uniformly and stably obtain an adhesive sheet in a semi-cured state, and to maintain storage stability at room temperature. The object of the present invention is to provide an adhesive sheet that has excellent properties, good adhesion at low flow properties, and has satisfactory heat resistance, moisture resistance, and chemical resistance.

[Means for Solving the Problems] In order to achieve objective 1f of item L, the present inventor has conducted extensive research and has found that the following adhesive sheet is significantly superior to conventional adhesive sheets. I found it.

That is, a thermosetting epoxy resin composition (A) and a thermosetting epoxy resin composition that does not or is difficult to cure when heated at the curing temperature of (A), but cures when heated at a higher temperature. Acrylate resin composition (B) and this mixture (C) are mixed with inorganic and organic! The above in the mixture (C) is impregnated or coated on a base material made of at least one type of A fiber, or formed into a sheet or film, and heated at the curing temperature of the above (A). By using an adhesive sheet in which only (A) is cured, it becomes 7g2.

A detailed description of the invention is provided below.

Thermosetting epoxy resin composition used for undeveloped IJ1 (
A) contains an epoxy resin and at least one type of curing agent selected from amine curing agents, polyamide curing agents, and imidazole curing agents as essential components.

First, the epoxy resin used in the present invention includes, for example, glycidyl ether of polyhydric phenols such as bisphenol A, bisphenol F, phenol novolak resin, and cresol novolac resin, and glycidyl ether of polyhydric alcohols such as butanediol and polypropylene glycol. Examples include glycidyl-type epoxy resins such as glycidyl esters of carboxylic acids such as ether, phthalic acid, and tetrahydrophthalic acid, and alicyclic-type epoxy resins obtained by epoxidizing intramolecular orphine bonds with peracetic acid or the like.

The epoxy curing agent used in the present invention is 50 to 12
Those that can cure the epoxy resin sufficiently in the temperature range of 0° C. are selected. For example, aliphatic polyamines such as diethylenetriamine and diethylaminopropylamine, alicyclic polyamines such as menthene diamine and isophorone diamine, metaphenylene diamine, Amine compounds such as aromatic amines such as diaminodiphenylmethane, polyamide compounds produced by condensation of dimer acid and polyamine, fast-curing imidazole compounds such as 2-methylimidazole and 2-ethyl-4-methylimidazole, etc. Can be mentioned.

These curing agents are preferably those capable of curing the epoxy resin within the range of 50 to 120°C. This is 50℃
A curing agent that has high curing properties at a lower temperature will have a very short bot life, resulting in poor workability, and if the temperature is higher than 120°C, the curing reaction (B) will also proceed gradually. It is preferable that the epoxy resin be cured to form a vine hardening agent within this temperature range, more preferably from 70°C to 10°C.

These curing agents are appropriately selected depending on the type of epoxy resin mentioned above and usage conditions.

In addition, a tertiary amine such as benzyldimethylamine, a compound having a phenolic hydroxyl group such as salicylic acid, etc. may be used as a curing accelerator, if necessary.

Next, the thermosetting epoxy methacrylate resin composition (B) used in the present invention contains an epoxy methacrylate resin, a copolymerizable crosslinking agent, and a radical combination initiator as essential components.

First, the epoxy methacrylate resin used in the present invention is a bisphenol type epoxy methacrylate resin, which is an addition reaction product of a bisphenol A type or bisphenol F type epoxy resin and methacrylic acid, a phenol novolac epoxy resin, or a cresol novolac epoxy resin. and methacrylic acid; an aliphatic epoxy methacrylate resin that is an addition reaction product of a glycidyl ether type epoxy resin of polyhydric alcohols and methacrylic acid; Any one
The main ingredient is seeds. Further, in the present invention, an epoxy acrylate resin which is an addition reaction product of these epoxy resins and acrylic acid can also be used after being copolymerized with an epoxy methacrylate resin, if necessary.

Examples of copolymerizable crosslinking agents include acrylic esters such as diallylphthalate, triethylene glycol diacrylate, and trimethylene propane triacrylate;
It is possible to use a monomer or a prepolymer thereof having two or more terminal unsaturated groups that react with epoxy methacrylate resins such as trimethylolpropane trimethacrylate and polypropylenes. It is preferable to use these copolymerizable crosslinking agents that have almost no pressability at temperatures below 120°C. This is because if there is pressability, the copolymerizable crosslinking agent will be pressed and reduced during curing of the thermosetting epoxy resin composition (A).

The copolymerizable crosslinking agent is epoxy methacrylate resin 10
10 to 200 parts by weight, preferably 5 parts by weight
0-100 It is preferable that it is a welfare department. If it is less than 50 parts by weight, the epoxy methacrylate resin composition (B
) becomes more viscous, resulting in poor workability;
If the amount exceeds 1 part by weight, the performance of the cured product will deteriorate, which is not preferable.

Next, the radical polymerization initiator is, for example, cumene hydroperoxide, t-butyl hydroperoxide, dicumyl peroxide, di-t-butyl peroxide, 2
．． Preferred are those that decompose and generate radicals when heated within the range of 100 to 200°C, such as 5-dimethyl-2,5-di-t-butylperoxyhexane. This is because if radicals are generated at a temperature lower than 100°C, the curing of (B) will proceed while curing of (A).
In addition, if the temperature is higher than 200°C, workability during bonding will deteriorate when using an adhesive sheet, and equipment and fuel costs will increase. More preferably, the temperature range is from 120°C to 170°C.
! Delicious.

Next, the mixing ratio of (A) to (B) is 1/
It is desirable that it be within the range of 9 to 9/l.

If it is smaller than 1/9, ′! The surface of the A-shaped adhesive sheet becomes extremely sticky, and if the ratio is greater than 9/l, the proportion of unreacted (8) contained in the adhesive sheet is too small, resulting in a decrease in adhesive strength. 9 preferably from 3/7 to 7/3
is preferred.

In addition to the above (A) and (B), the composition of the present invention may optionally contain a solvent having a boiling point of 120"C or less, such as acetone or methyl ethyl ketone, a flame retardant, a thixotropy imparting agent, and a filler. , a reactive diluent, a leveling agent, an antifoaming agent, etc. can be added.

The present invention relates to the use form in which the above-mentioned mixed resin set J&Things (C) is impregnated or coated on a base material made of at least one of inorganic fibers and organic fibers, and the use form in which it is formed into a sheet shape or a film shape. There are two ways to use oT1 enemies.

Examples of the substrate impregnated or coated with the mixture (C) include sam!, such as glass, silica, and asbestos.
A woven fabric, a nonwoven fabric, a mat, or a combination of these materials is used.

In addition, the sheet-like adhesive sheet is coated onto a film having mold releasability such as a fluororesin film using a curtain coater, roll coater, knife coater, etc., depending on the coating thickness, and then coated with the above (A). ) is cured by heating at a curing temperature.

[Actions of the Invention] This section 9.11 has the following effects by adopting the following measures.

First, epoxy resins are generally cured by an addition reaction with the official group of a curing agent through a ring-opening reaction of the epoxy ring. The curing reaction of an epoxy resin using an amine curing agent, which is a typical curing agent, is shown below.

→R-C1l□-CIl-C1,-Nll-R'・-(
1) Next, in general, thermosetting epoxy methacrylate resins are cured by the generation of radicals by decomposition of peroxide, which converts the terminal unsaturated groups into radical nails. The curing reaction formula of epoxy methacrylate resin is shown below.

R-0-0-R' → R-0・+ ・0-R'
・-(2)0■ ・-(3) In the present invention, the reactivity between the epoxy group and the curing agent shown in formula (1) is different from the decomposability of peroxide shown in formula (2). The epoxy resin curing agent and peroxide are selected to be within the temperature range. That is, a thermosetting epoxy resin composition (A) containing an epoxy group and an epoxy resin curing agent that exhibits high reactivity within the range of 50 to 120°C;
A thermosetting epoxy methacrylate resin composition (B) containing a peroxide that exhibits high decomposability within the range of 0 to 200°C and generates radicals is mixed. This mixture (
When C) is impregnated or applied onto a substrate, or formed into a sheet or film, and heated within a range of 50 to 120°C, only the above (A) in the mixture (C) is cured. As a result, the above (C) becomes a semi-cured state as a whole. Furthermore, by changing the mixing ratio of (A) and (B), any semi-cured material can be selected.

Here, we will discuss the addition reaction called the Michael reaction between the curing agent amine (and the vinyl group of the epoxy methacrylate resin or copolymerizable crosslinking agent).
When heated within the range of 50 to +20'C, this Michael reaction occurs! -0, the epoxy methacrylate resin will also be cured, and therefore (C) will not be in the desired semi-cured state.

However, this Michael reaction requires a high temperature for the reaction to occur except in the presence of a highly basic catalyst. Almost never occurs.

Next, a detailed explanation will be given of the performance of the adhesive sheet of the present invention.

As mentioned above, the adhesive sheet made by the above (C) can be in a semi-cured state as desired by changing the mixing ratio of the above (A) and the above (B).
Since (B) hardly reacts when heated within the range of 'c, it is possible to always obtain an adhesive sheet in a stable semi-cured state without strict control of the curing conditions. Also, of course, the above (B) does not react even at room temperature, so
The adhesive sheet has excellent storage stability.

Next, in applications where it is desired to obtain strong adhesive strength without the resin flowing, if the desired semi-cured state is obtained by adjusting the mixing ratio of (A) and (8), the curing of (A) will produce Said (
C) Since the three-dimensional network structure of (A) is formed throughout, the resin does not melt even when pressed at high temperature and high pressure, so the resin hardly flows. However, the adhesive sheet contains unreacted (8), which is the reason for increasing the adhesive strength.

The cured product obtained by heating the adhesive sheet of the present invention within the range of 100 to 200"C and also curing the above-mentioned (B) has the excellent heat resistance of the cured epoxy resin because it forms an interpenetrating polymer network structure. It is possible to obtain a cured product that has the excellent flexibility, high toughness, and impact resistance of a cured epoxy methacrylate resin.

[Examples] Next, the present invention will be specifically explained using Examples, but the present invention is not limited to the following Examples. In the following examples, "r parts" means "parts by weight."

100 parts of bisphenol A type epoxy resin (E-1001, manufactured by Yuka Shell Co., Ltd., with a molecular weight of 950) and 1 part of Laromin C-260 (manufactured by BASF Corporation) as a hardening agent.
2.5 parts were mixed and this was used as composition (a). In addition, bisphenol A type epoxy methacrylate resin (average molecular weight 1000, Neo Ball 8 manufactured by Nippon Yubika Co., Ltd.)
104) 100 parts, 75 parts of sialifthalate (manufactured by Osaka Sakutatsu Co., Ltd.) as a copolymerizable flavoring agent, Bark Mill D (F) (manufactured by NOF Corporation) as a radical polymerization initiator, 1
．． 8 parts were combined and used as composition (b). and,(
a) Composition and (b) Composition are mixed in a ratio of 2:1 and the viscosity is 1.
Methyl ethyl ketone was added to the mixture to give an impregnating varnish of 0.00 cl's.

Next, a glass cloth having a thickness of 30 ILm was impregnated with this impregnating varnish, and dried and cured at 80° C. for 40 minutes to obtain an adhesive sheet.

Example 2 In Example 1, ester T was added to N as a copolymerizable crosslinking agent.
The procedure was the same as in Example 1, except that 100 parts of MPT (manufactured by Shin-Nakamura Kogyo Co., Ltd.) and 2 parts of Perbutyl D (manufactured by NOF Corporation) were used as a radical polymerization initiator.

Example 3 In Example 1, (a) composition and (b) composition were mixed in l:l ratio.
The procedure was the same as in Example 1, except that the mixture was mixed.

Example 4 100 parts of bisphenol A type epoxy resin (E-828 manufactured by Yuka Shell Co., Ltd.) and 40 parts of Kayahard A-A (manufactured by Nippon Kayaku Co., Ltd.) as a hardening agent were mixed. And let this be (a') set rJ, a thing. In addition, bisphenol A type methacrylate resin (-+-uniform molecular rB
+ooo, Neo Ball 8104 manufactured by Nippon U-Pica Co., Ltd.)
100 parts, diallyl phthalate (as a copolymerizable crosslinking agent)
(manufactured by Osaka Sakutatsu Co., Ltd.) as a radical polymerization initiator, and 1.8 parts of Percmil D (F) (manufactured by 11 Hon Yushi Co., Ltd.) were mixed into (b')! lIJ & things. Then, the composition (a') and the composition (b') were mixed at 2:l'''C.
'C mixed varnish.

Next, this varnish was applied onto a Teflon film using a knife coater and cured at 100° C. for 90 minutes to form a 71# adhesive sheet with a coating thickness of 50 gm.

lid 5 In Example 4, NK Kostel T was used as a copolymerizable crosslinking agent.
100 parts of MPT (manufactured by Shin-Nakamura Chemical Co., Ltd.) and Verbutyl D (manufactured by Ippon Yushi Co., Ltd.) as a radical polymerization initiator.
The procedure is the same as in Example 4 except that two parts are used.

Example 6 Example 4 was carried out in the same manner as in Example 4 except that (a') set J& product and (b') composition were mixed at a ratio of 1:1.

Comparative example A Commercially available prepreg adhesive sheet.

Comparative example B Sheet-shaped reprint adhesive sheet.

The adhesive sheets obtained in Examples and the commercially available adhesive sheets of Comparative Examples were evaluated by the following method, and the results are shown in the table.

(Rate of change over time): The calorific value before and after heat treatment at too'c for 2 hours was measured by DSC, and the change was determined from the formula shown below.

Change over time (Pe = Heat - Calorific value before treatment (resin protrusion): A hole with a diameter of 2 cm was made in the center of the adhesive sheet cut into 1Oc square, and the temperature was 170℃, the pressure was 40kgf/crn', and the pressing time was 60 minutes. After molding under press conditions, the maximum length of the resin protruding into the hole was measured.

(Adhesive strength): (Normal state) Thickness: An adhesive sheet is sandwiched between a copper plate of I51Lm and a glass evo board, and the temperature is 14C1 at 170℃.
4O/crry', 1c after pressing for 60 minutes
■Cut to width and measure beer strength.

(After ,8 treatments) Beer strength after 240 sowing times at +150°C.

(After moisture absorption): Beer strength after 100 hours at PCT (121'C2 atm).

As is clear from the table, the rate of change over time in each Example was approximately 0, which indicates that almost no hardening progressed even before and after heat treatment. This shows that the adhesive sheet of the invention) has extremely excellent storage stability at room temperature.

Furthermore, the protrusion of the resin takes almost the same value if the ratios of (A) and (B) are the same, and the amount of resin protrusion can be controlled arbitrarily by changing the ratio of (A) and (B). I understand.

On the other hand, good adhesive strength results were obtained even when the resin protrusion was small. Moreover, it was revealed that the decrease in adhesive strength after heat treatment or moisture absorption was smaller than that of the comparative example, and the heat resistance and moisture resistance were good.

[Effects of the Invention] As is clear from the Examples, the adhesive sheet of the present invention had the following advantages.

1. Since (+1) hardly reacts at the heating temperature used to make the semi-cured state, an adhesive sheet always having a uniform semi-cured state can be obtained.

2. Since (B) does not react even at room temperature, an adhesive sheet with extremely excellent storage stability can be obtained.

3. The resin flow can be determined by the mixing ratio of (A) and (B), and a stable flow can always be obtained.

4. Since unreacted (B) is present in the adhesive sheet, good adhesive strength can be obtained even when the resin flow is small.

5. Since it does not contain rubbery components, it is heat resistant, moisture resistant,
Excellent chemical resistance.

As described above, it is possible to obtain an adhesive sheet with extremely superior performance compared to conventional adhesive sheets, so it is useful in industry.

Claims (12)

[Claims] (1) Thermosetting epoxy resin composition (A) and the above (A
) is mixed with a thermosetting epoxy methacrylate resin composition (B) that does not cure or is difficult to cure when heated at a curing temperature of 1.), and which cures when heated at a temperature higher than that, and this mixture (C) is By forming it into a sheet or film and heating it at the curing temperature of (A),
A thermosetting adhesive sheet characterized in that only (A) in the mixture (C) is cured. (2) The above (A) is an epoxy resin and an amine curing agent,
The thermosetting adhesive sheet according to claim 1, characterized in that it contains at least one type of curing agent selected from a polyamide curing agent and an imidazole curing agent as an essential component. (3) The heat according to claim 1 or 2, wherein the curing agent contained in (A) is a curing agent capable of curing the epoxy resin within a range of 50 to 120°C. Curable adhesive sheet. (4) The above (B) is a bisphenol-type epoxy methacrylate resin obtained by adding methacrylic acid to a bisphenol-type epoxy resin, a novolak-type epoxy methacrylate resin obtained by adding methacrylic acid to a novolak-type epoxy resin, or a polyhydric alcohol. Essential components include at least one selected from resin group type epoxy methacrylate resins obtained by adding methacrylic acid to glycidyl ether type epoxy resins, a copolymerizable crosslinking agent, and a radical polymerization initiator. A thermosetting adhesive sheet according to any one of claims 1 to 3, characterized in that: (5) The radical polymerization initiator contained in the above (B) is 10
The thermosetting adhesive sheet according to any one of claims 1 to 4, characterized in that it decomposes within the range of 0 to 200°C and generates radicals. (6) The mixing ratio of (A) to (B) is 1/9.
The thermosetting adhesive sheet according to any one of claims 1 to 5, wherein the thermosetting adhesive sheet is within the range of 9/1 to 9/1. (7) Thermosetting epoxy resin composition (A) and the above (A
) is mixed with a thermosetting epoxy methacrylate resin composition (B) that does not cure or is difficult to cure when heated at a curing temperature of 1.), and which cures when heated at a temperature higher than that, and this mixture (C) is Only the above (A) in the mixture (C) was cured by impregnating or applying it to a base material consisting of at least one of inorganic fibers and organic fibers and heating it at the curing temperature of above (A). A thermosetting adhesive sheet characterized by: (8) The above (A) is an epoxy resin and an amine curing agent,
8. The thermosetting adhesive sheet according to claim 7, which contains at least one type of curing agent selected from a polyamide curing agent and an imidazole curing agent as an essential component. (9) The heat according to claim 7 or 8, wherein the curing agent contained in (A) is a curing agent capable of curing the epoxy resin within a range of 50 to 120°C. Curable adhesive sheet. (10) The above (B) is a bisphenol-type epoxy methacrylate resin in which methacrylic acid is added to a bisphenol-type epoxy resin, a novolak-type epoxy methacrylate resin in which methacrylic acid is added to a novolak-type epoxy resin, and polyhydric alcohols. The essential components are at least one selected from aliphatic epoxy methacrylate resins obtained by adding methacrylic acid to glycidyl ether type epoxy resins, a copolymerizable crosslinking agent, and a radical polymerization initiator. A thermosetting adhesive sheet according to any one of claims 7 to 9. (11) The radical polymerization initiator contained in (B) is 1
The thermosetting adhesive sheet according to any one of claims 7 to 10, characterized in that it decomposes and generates radicals within the range of 00 to 200°C. (12) The mixing ratio of (A) to (B) is 1/
The thermosetting adhesive sheet according to any one of claims 7 to 11, characterized in that it is within the range of 9 to 9/1.