JP6817592B2 - Thermosetting adhesive film - Google Patents

Description

The present invention relates to a thermosetting adhesive film.

With the development of the electronics field, there is an increasing demand for miniaturization, thinning, weight reduction, and high density of electronic devices. Further, there is an increasing demand for a flexible device that can be arranged on a curved surface, an uneven surface, or the like, freely deformed, or bent according to the application.

Thermosetting resins have conventionally been used in a wide range of fields such as electronic materials and optical materials due to their excellent heat resistance, chemical resistance, moldability, insulation reliability, and the like. In particular, an adhesive film using a thermosetting resin is suitably used for interlayer bonding of various electronic components, bonding and fixing of an IC module and an IC card, and the like.

For example, Patent Document 1 provides a thermosetting adhesive composition and an adhesive sheet that are excellent in adhesiveness, heat resistance, and flexibility, and in particular, can maintain insulation reliability even after being exposed to a high humidity atmosphere for a long period of time. It is selected from the group consisting of an acrylic resin (A), an additive polyester resin (B) having a cyclic structure in the main chain, an epoxy group-containing compound, an isocyanate-containing compound, and a blocked isocyanate group-containing compound. An adhesive sheet containing an adhesive layer formed of a thermosetting adhesive composition containing at least one compound (C) is disclosed.

Further, Patent Document 2 aims to provide a thermosetting film-like adhesive sheet which has flexibility to absorb bending stress and impact and can prevent deformation at high temperature. (A) Nitrile-butadiene rubber , (B) Phenol formaldehyde and (C) Hexamethylenetetramine are dissolved in (D) an organic solvent, and then the organic solvent is removed to a concentration that does not substantially remain, so that the thickness is 10 to 150 μm. A thermosetting film-like adhesive sheet using a film is disclosed.

However, although thermosetting sheets as described in Patent Documents 1 and 2 have excellent properties such as adhesion and heat resistance, they do not have a large extensibility that allows them to be freely deformed in terms of flexibility. , It is hard to say that sufficient growth has been obtained. It was not sufficiently stretchable for devices that require wearability and shape followability, such as flexible batteries such as solar cells, medical fields, decorative fields, and in-vehicle fields.

On the other hand, the liquid thermosetting epoxy resin composition is composed of a cyclic aliphatic skeleton, an alicyclic epoxy compound having two or more epoxy groups in the molecule, and a polyol oligomer having two or more terminal hydroxyl groups. A composition containing a main agent, a curing agent and a curing accelerator has been reported (Patent Document 3). However, since such a liquid thermosetting resin composition cannot be stored in the B stage (semi-cured state), an adhesive film cannot be obtained using the resin composition.

Japanese Unexamined Patent Publication No. 2013-159762 Japanese Unexamined Patent Publication No. 2006-210867 International release WO2006 / 064736

The present invention has been made in view of the above-mentioned circumstances, and provides an adhesive film having good adhesiveness and heat resistance, as well as storage stability as an adhesive film (B stage storage stability) and high extensibility. The purpose is to do.

The thermosetting adhesive film according to one aspect of the present invention is solid with 30 to 80% by mass of a polyol resin having a weight average molecular weight of 100,000 to 1,000,000 and a hydroxyl value of 60 mgKOH / g to 110 mgKOH / g. It is characterized by containing at least 10 to 50% by mass of an epoxy resin and 10 to 50% by mass of an acid anhydride.

In the thermosetting adhesive film, the softening point of the solid epoxy resin is preferably 40 ° C. or higher, and the weight average molecular weight is preferably 800 or higher.

Further, in the thermosetting adhesive film, it is preferable that the equivalent of the acid anhydride is 200 or more and the number average molecular weight is 400 or more.

The film according to another aspect of the present invention is a film obtained by curing the above-mentioned thermosetting adhesive film.

According to the present invention, it is possible to provide an adhesive film having storage stability as an adhesive film (B stage storage property) and high extensibility in addition to adhesion and heat resistance. Further, the adhesive film having such characteristics can be applied to a device that requires wearability and shape followability.

As a result of diligent studies, the present inventors have obtained excellent adhesion and heat resistance by using a polyol resin, an acid anhydride and a solid epoxy having predetermined properties, as well as storage stability and high elongation at the B stage. We have found that an adhesive film having properties can be obtained, and based on this finding, further research has been carried out to reach the present invention.

In the present embodiment, good B-stage storage stability means that the adhesive film stored at 20 ° C. for 1 month is laminated with the adherend and cured, and the adhesion is not deteriorated as compared with the initial product. It refers to the characteristic.

Further, in the present embodiment, high extensibility means that the elongation up to tensile fracture at room temperature (23 ° C.) measured by the tensile property evaluation is large.

Hereinafter, embodiments according to the present invention will be specifically described, but the present invention is not limited thereto.

The thermosetting adhesive film of the present embodiment contains 30 to 80% by mass of a polyol resin having a weight average molecular weight of 100,000 to 1,000,000 and a hydroxyl value of 60 mgKOH / g to 110 mgKOH / g, and a solid epoxy resin 10. It is characterized by containing at least ~ 50% by mass and 10 to 50% by mass of an acid anhydride.

(Polyol resin)
The polyol resin used in the present embodiment is not particularly limited as long as it has a weight average molecular weight of 100,000 to 1,000,000 and a hydroxyl value of 60 mgKOH / g to 110 mgKOH / g.

When the weight average molecular weight is 100,000 to 1,000,000, the solvent solubility becomes good, and a highly stretchable thermosetting adhesive film having excellent film forming ability can be obtained. If the weight average molecular weight is less than 100,000, the film forming ability is lowered. On the other hand, when the weight average molecular weight is larger than 1,000,000, the solvent solubility decreases. Further, when the hydroxyl value is from 60 mgKOH / g to 110 mgKOH / g, an adhesive film having good heat resistance and extensibility can be obtained. If the hydroxyl value is less than 60 mgKOH / g, the heat resistance is lowered, and if the hydroxyl value is more than 110 mgKOH / g, the extensibility is lowered.

Preferred specific examples of the polyol resin include, for example, glycols, polyether polyols, acrylic polyols, polyester polyols and the like. The acrylic polyol can be obtained by copolymerizing an acrylic monomer having a hydroxyxy group such as hydroxyethyl methacrylate with another acrylic monomer or styrene. The polyester polyol is obtained by a condensation reaction of a polyhydric alcohol such as trimethylolpropane or 1,6-hexanediol with a polybasic acid. The polyether polyol can be obtained by ring-opening polymerization of ethylene oxide or the like. Among these polyols, acrylic polyols can be preferably used. These may be used individually by 1 type, or may be used in combination of 2 or more type, if necessary.

The adhesive film of the present embodiment contains 30 to 80% by mass of the polyol resin as described above. By including the polyol resin in this range, a highly stretchable thermosetting adhesive film can be obtained more reliably. A more preferable content of the polyol resin is 30 to 60% by mass.

(Solid epoxy resin)
The solid epoxy resin contained in the adhesive film of the present embodiment is not particularly limited as long as it is a solid epoxy resin at room temperature.

Specifically, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac epoxy resin, cresol novolac epoxy resin, triphenylmethane type epoxy resin, dicyclopentadiene type epoxy resin, phenol aralkyl epoxy resin, biphenol aralkyl. Examples thereof include epoxy resins and trisphenol type epoxy resins. These may be used individually by 1 type, or may be used in combination of 2 or more type, if necessary.

In particular, from the viewpoint of obtaining a film with no tack (stickiness) on the film surface so as not to bite air bubbles when laminating the adhesive film on the adherend, the softening point is 40 ° C. or higher and the weight average molecular weight is 800 or higher. It is preferable to use a solid epoxy resin.

Commercially available epoxy resins can be used as such epoxy resins. Specifically, JER1003 (weight average molecular weight 1300 manufactured by Mitsubishi Chemical), JER1004 (weight average molecular weight 1650 manufactured by Mitsubishi Chemical) and the like as bisphenol A type epoxy resins can be used. Is preferable.

The adhesive film of the present embodiment contains 10 to 50% by mass of the solid epoxy resin as described above. By including the solid epoxy resin in this range, the thermosetting adhesive film can more reliably have heat resistance.

(Acid anhydride)
The acid anhydride used in the present embodiment is not particularly limited, and is, for example, 1,2,3,6-tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 4-methylhexahydrophthalic anhydride, methylbicyclo [2]. .2.1] Heptane-2,3-dicarboxylic acid anhydride, bicyclo [2.2.1] heptane-2,3-dicarboxylic acid anhydride, glycerin bisamhydrotrimerotate monoacetate and the like can be used. .. These may be used individually by 1 type, or may be used in combination of 2 or more type, if necessary.

Among them, an acid anhydride having an equivalent of 200 or more and a number average molecular weight of 400 or more can be preferably used. When such an acid anhydride is used, it has low volatility (for example, when it is left at 160 ° C. for 15 minutes, the volatile component excluding the volatilization of water is 0.5% or less), and the adhesive film can be laminated on both sides. There is an advantage that it becomes possible. On the other hand, when the equivalent of the acid anhydride is less than 200 and the molecular weight is less than 400, it is possible to laminate the adhesive film on one side, but it may be difficult to laminate the adhesive film on both sides because volatile gas is generated.

In particular, it is preferable that the acid anhydride is a polyfunctional alicyclic acid anhydride containing a skeletal structure represented by the following chemical formula (1).

By using such a polyfunctional alicyclic acid anhydride, volatile gas is not generated at the time of curing after laminating the adhesive film, so that the adherend can be laminated on both sides of the adhesive film, and the adhesive film without coloring can be obtained. It has the advantage of being obtained.

The adhesive film of the present embodiment contains 10 to 50% by mass of the acid anhydride as described above. By containing an acid anhydride in this range, an adhesive film having excellent adhesion and heat resistance can be obtained.

(Other additives)
The adhesive film of the present embodiment may contain, for example, a curing agent or the like in addition to the above-mentioned components. The curing agent is not particularly limited as long as it works as a curing agent for a thermosetting resin. In particular, examples of a phenol resin, an amine compound, an acid anhydride, an imidazole compound, a sulfide resin, and a dicyandiamide that can be preferably used as a curing agent for an epoxy resin can be mentioned. In addition, a light / ultraviolet curing agent, a thermal cation curing agent, and the like can also be used. Depending on the situation, one of these may be used alone, or two or more thereof may be used in combination.

In addition, the adhesive film of the present embodiment includes other additives such as a cross-linking agent, a curing catalyst (curing accelerator), a flame retardant, a flame retardant aid, a leveling agent, and a colorant as long as the effects of the present invention are not impaired. , Inorganic filler (for example, electrically conductive filler, thermally conductive filler, etc.) and the like may be contained as required.

(Manufacturing method of adhesive film)
The method for preparing the thermosetting adhesive film of the present embodiment is not particularly limited, and can be obtained by, for example, the following method.

First, a polyol resin, a solid epoxy resin, an acid anhydride, a curing agent and, if necessary, other additives and a solvent are mixed so as to be uniform to obtain a resin solution. The solvent used in this embodiment is not particularly limited, and for example, toluene, xylene, methyl ethyl ketone, acetone and the like can be used. These solvents may be used alone or in combination of two or more. Further, if necessary, an organic solvent for adjusting the viscosity and various additives may be blended.

By heat-curing the resin solution obtained as described above, the adhesive film of the present embodiment can be obtained by semi-curing while evaporating the solvent.

The method, apparatus, and conditions for heat-curing the resin solution may be various means similar to the conventional ones or improved means thereof. The specific heating temperature and time can be appropriately set depending on the cross-linking agent and solvent used, and for example, the resin solution is cured and adhered by heating at 50 to 200 ° C. for about 60 to 120 minutes. You can get the film.

The thickness of the adhesive film of the present embodiment obtained as described above is not particularly limited and can be appropriately adjusted according to the intended use. Specifically, for example, a thickness of 10 μm to 100 μm is preferable from the viewpoint of handleability, optical characteristics, and wearability.

The adhesive film of the present embodiment thus obtained has not only adhesiveness and heat resistance, but also storage stability as an adhesive film (B stage storage stability) and high extensibility. The adhesive film of the present embodiment having such characteristics is also used in devices that require wearability and shape followability, such as flexible batteries such as solar cells, medical fields, decorative fields, and in-vehicle fields. It seems to be applicable.

As described above, this specification discloses various aspects of technology, of which the main technologies are summarized below.

The thermosetting adhesive film according to one aspect of the present invention is solid with 30 to 80% by mass of a polyol resin having a weight average molecular weight of 100,000 to 1,000,000 and a hydroxyl value of 60 mgKOH / g to 110 mgKOH / g. It is characterized by containing at least 10 to 50% by mass of an epoxy resin and 10 to 50% by mass of an acid anhydride.

With such a configuration, it is possible to provide an adhesive film having not only adhesiveness and heat resistance but also storage stability as an adhesive film (B stage storage stability) and high extensibility.

In the thermosetting adhesive film, the softening point of the solid epoxy resin is preferably 40 ° C. or higher and the molecular weight is preferably 800 or higher. As a result, a film having no tack (stickiness) on the surface of the film can be obtained, and there is an advantage that air bubbles can be prevented from being caught when the adhesive film is laminated on the adherend.

Further, in the thermosetting adhesive film, it is preferable that the equivalent of the acid anhydride is 200 or more and the number average molecular weight is 400 or more. This has the advantage that the adherend can be laminated on both sides of the thermosetting adhesive film.

The film according to another aspect of the present invention is a film obtained by curing the above-mentioned thermosetting adhesive film. Since the film of the present invention is a film having high adhesion, heat resistance and extensibility, it can be suitably used for devices and the like that require wearability and shape followability.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited thereto.

(Preparation of polyols A1 to A8)
First, the polyol was prepared by the following method.

Polymer A was prepared by blending each monomer according to the blending table shown in Table 1 below.

1300 parts by mass of water was placed in a four-necked flask equipped with a stirrer, 3 parts by mass of polyvinyl alcohol was dissolved as a dispersion stabilizer, and 430 parts by mass of a mixture in which each monomer component was mixed at the mass ratio shown in Table 1 while stirring. A suspension was prepared by adding 4 parts by mass of 2,2'-azobisisobutyronitrile as a part and a polymerization initiator. The suspension was heated to 68 ° C. with stirring and kept constant for 4 hours for reaction. Then, it cooled to room temperature (about 25 degreeC). Next, the reactants were solid-liquid separated, thoroughly washed with water, and then dried using a dryer to obtain polyol A (Synthesis Examples 1 to 8).

The weight average molecular weight Mw and solvent solubility of the polyols A obtained in Synthesis Examples 1 to 8 were evaluated. The results are shown in Table 1. For the solubility, a sample in which 15% by mass was dissolved in toluene was accepted, and a sample insoluble was rejected. Since the polyol resin A8 prepared in Synthesis Example 8 was insoluble in 15% toluene, it could not be used in Examples described later.

(Preparation of polyol C)
Polyethylene glycol (weight average molecular weight: 35,000), α-cyclodextrin (hereinafter, may be simply abbreviated as “α-CD”), and polyol A composed of an adamantanamine group were prepared by the following method.

10 g of PEG (molecular weight 35,000), 100 mg of TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy radical) and 1 g of sodium bromide were dissolved in 100 ml of water. To the obtained solution, 5 ml of an aqueous sodium hypochlorite solution (effective chlorine concentration of about 5%) was added, and the mixture was reacted with stirring at room temperature. It was prepared by adding 1N NaOH so as to maintain pH: 10-11. The decrease in pH disappeared within approximately 3 minutes, but the mixture was further stirred for 10 minutes. Ethanol was added in a range of up to 5 ml to terminate the reaction. Extraction with 50 ml of methylene chloride was repeated three times to extract components other than the inorganic salt, and then methylene chloride was distilled off with an evaporator. After dissolving in 250 ml of warm ethanol, only PEG-carboxylic acid was precipitated in a freezer at -4 ° C overnight. The precipitated PEG-carboxylic acid was recovered by centrifugation. This cycle of hot ethanol dissolution-precipitation-centrifugation was repeated several times, and finally dried by vacuum drying to obtain PEG-carboxylic acid.

After dissolving 3 g of the PEG-carboxylic acid and 12 g of α-CD prepared above in 50 ml of warm water at 70 ° C. prepared separately, the two were mixed, and then allowed to stand in a refrigerator (4 ° C.) overnight. The inclusion complex precipitated in the form of cream was freeze-dried and recovered. At room temperature, 0.13 g of adamantaneamine was dissolved in 50 ml of dimethylformamide (DMF), added to 14 g of the polyol obtained above, and then swirled promptly and well. Subsequently, 0.38 g of a BOP reagent (benzotriazole-1-yl-oxy-tris (dimethylamino) phosphonium / hexafluorophosphate) dissolved in 25 ml of DMF was added, and the mixture was similarly shaken well. Further, 0.14 ml of diisopropylethylamine dissolved in 25 ml of DMF was added, and the mixture was similarly shaken well. The resulting mixture was allowed to stand in the refrigerator overnight. Then, 100 ml of a DMF / methanol = 1: 1 mixed solution was added, mixed well, centrifuged, and the supernatant was discarded. After washing with this DMF / methanol mixed solution was repeated twice, washing with 100 ml of methanol was repeated twice by the same centrifugation. The obtained precipitate was vacuum dried and then dissolved in 50 ml of dimethyl sulfoxide (DMSO), and the obtained transparent solution was added dropwise to 700 ml of water to precipitate a polyol. The precipitated polyol was recovered by centrifugation and vacuum dried or lyophilized. This DMSO dissolution-precipitation-recovery-drying cycle in water was repeated twice to finally obtain purified polyol B.

After a part of the OH group of α-CD of the polyol B was further hydroxypropylated, 20 g of the obtained prepared product was placed in a three-necked flask, and 90 g of ε-caprolactone was introduced while slowly flowing nitrogen. After uniformly stirring at 130 ° C. for 60 minutes with a mechanical stirrer, 6 g of tin 2-ethylhexanoate (50% by mass solution) diluted with toluene in advance was added, and the mixture was reacted for 5 hours to remove the solvent and the reaction product. 110 g was obtained. In addition, the obtained polyol had a weight average molecular weight Mw of 600,000 by GPC. The hydroxyl value was 73 mgKOH / g. The solvent was removed, and a polyol having a side chain modified with polycaprolactone was obtained as a solid to obtain a polyol C.

The molecular weight and molecular weight distribution of the synthesized polyol were measured by a PU610-1X GPC device of GL Sciences Co., Ltd. The hydroxyl value and acid value were measured by a method according to JIS 0070-1992.

(Preparation of acid anhydride A)
The abbreviations of the compounds in the preparation of acid anhydride A are as follows.
Ricabinol HB: Hydrogenated bisphenol A (manufactured by New Japan Chemical Co., Ltd.)
Ricacid HH: Hexahydrophthalic anhydride (manufactured by New Japan Chemical Co., Ltd.), number average molecular weight 154, acid anhydride equivalent 154 g / eq
To 17.6 g (73.0 mmol) of licabinol HB in 15.0 g of cyclohexanone, 22.5 g (146.0 mmol, 2.0 times mmol of ricabinol HB) was added, and the mixture was stirred at 110 ° C. for 3 hours under a nitrogen stream. A solution of a dicarboxylic acid compound (HB / HH) cyclohexanone was obtained.

To this dicarboxylic acid compound solution was added 26.1 g of acetic anhydride (255.5 mmol, 3.5 times mmol with respect to ricabinol HB), and the mixture was stirred at 100 ° C. under a nitrogen stream for 1 hour. Then, the pressure inside the reaction vessel is gradually reduced to 10.7 to 13.3 kPa, and then cyclohexanone is added dropwise into the reaction vessel at a rate of 60 ml / hour, while acetic acid produced as a by-product is 60 ml outside the reaction system together with cyclohexanone. A polycarboxylic acid anhydride solution was obtained by subjecting to a condensation reaction at 100 ° C. for 5 hours while distilling off at a rate of / hour. The equivalent was 1150 and the number average molecular weight was 4700. Then, it was diluted with butyl acetate and adjusted to 40% by weight of polycarboxylic acid anhydride.

The infrared absorption (FT-IR) spectrum, number average molecular weight, and acid anhydride equivalent of the obtained polycarboxylic acid anhydride were measured and calculated by the methods shown below.

<Infrared absorption (FT-IR) spectrum>
The obtained polycarboxylic acid anhydride solution was vacuum-dried, and the solvent was distilled off to obtain a flaky solid polycarboxylic acid anhydride. Regarding this polycarboxylic acid anhydride, a peak (1813 cm ^-1 ) showing an acid anhydride group was observed in the spectrum measured by FT-IR, and the desired polycarboxylic acid anhydride (acid anhydride A) was obtained. It was observed.

<Number average molecular weight>
About 0.1 g of a polycarboxylic acid anhydride solution is dissolved in 2 ml of tetrahydrofuran to prepare a sample solution for molecular weight measurement. For the number average molecular weight Mn, the polystyrene-equivalent number average molecular weight (Mn) was determined by using gel permeation chromatography (GPC).

<Acid anhydride equivalent>
Weigh 3.00 g of the polycarboxylic acid anhydride solution in an Erlenmeyer flask, and add 10 ml of pyridine to dissolve it. Further, 50 ml of ion-exchanged water is added, and the mixture is heated under reflux for 3 hours and then allowed to cool to room temperature (25 ° C.). After allowing to cool, 5 drops of a 1 wt% phenolphthalein solution was added, and titration was performed with a 0.5 M potassium hydroxide ethanol solution. The acid anhydride equivalent was calculated by applying the following formula (1). The acid anhydride equivalent (g / eq) is the mass of a polycarboxylic acid anhydride solution containing 1 mol of an acid anhydride group expressed in grams.

Acid anhydride equivalent = (B × 2 × 103) / (A × N) (1)
A: 0.5M potassium hydroxide ethanol solution (ml) used for titration
B: Sample collection amount (g)
N: Normality of potassium hydroxide ethanol solution

(Each material used)
The various materials used in this example and the comparative example are as follows.
-Polyform resin: The above polyol B
-Epoxy resin A: "JER1003" manufactured by Mitsubishi Chemical Corporation (7 to 8 methyl groups, bifunctional, weight average molecular weight 1300)
-Epoxy resin B: "JER828" manufactured by Mitsubishi Chemical Corporation (liquid bisphenol A type epoxy resin, weight average molecular weight 370)
-Acid anhydride A: Polycarboxylic acid anhydride prepared above-Acid anhydride B: Hexahydrophthalic anhydride (manufactured by Shin Nihon Rika Co., Ltd.) (number average molecular weight 154, acid anhydride equivalent 154 g / eq)
-Curing accelerator: "2E4MZ" manufactured by Shikoku Chemicals Corporation, 2 ethyl 4 methylimidazole

<Examples 1-11 and Comparative Examples 1-8>
A resin solution (varnish) was prepared by adding the solvent methyl ethyl ketone and uniformly mixing the mixture composition (parts by mass) shown in Table 2 below so that the solid content concentration was 40% by mass.

Next, the obtained resin composition was applied on a PET film (support) having a thickness of 75 μm with a bar coater, dried at 120 ° C. for 10 minutes, and the solvent was removed to obtain an adhesive film.

The adhesive film was then heat-cured at 170 ° C. for 60 minutes. The obtained cured product was used as a dumbbell No. 6 shape film (measurement site width 4 mm, parallel portion length 25 mm) having a thickness of 50 μm, and used as a sample in the evaluation of elongation described later.

<Evaluation method>
(Film property)
In the evaluation of the film property of the adhesive films of Examples and Comparative Examples, the adhesive films obtained by coating and drying did not allow air to enter during laminating, were not sticky, and could be handled as a film. .. On the other hand, if the varnish has poor solubility and is turbid due to incompatibility of the adhesive film obtained even after application and drying, or if the adhesive film is sticky such that air enters during laminating, it is judged as rejected. did.

(Adhesion)
A double-sided copper foil of a flexible substrate material R-F775 having a polyimide layer (thickness ratio: copper foil / polyimide / copper foil = 12 μm / 25 μm / 12 μm) was etched to obtain a polyimide film. An adhesive film was laminated on the polyimide film at 40 ° C., and a vacuum laminator was used to obtain a bonded product of the polyimide and the adhesive film at 0.3 MPa under pressure for 60 seconds. The bonded product was attached to an adhesive film, the PET film was peeled off, and then heated at 150 ° C. for 30 minutes to obtain a sample for adhesion evaluation. The adhesive film was peeled off from the polyimide, and those in which the adhesive film was not continuously peeled off were accepted.

(Stretchability)
A cured product film of dumbbell No. 6 shape (measurement site width 4 mm, parallel part length 25 mm) with a thickness of 50 μm obtained in each example and comparative example was pulled at a test speed of 25 mm / min and a temperature of 23 ° C. to stretch until fracture. evaluated. Those with an elongation of 100% or more were rejected, and those with an elongation of less than 100% were rejected.

(Solder heat resistance)
The adhesive films obtained in each Example and Comparative Example were heat-cured at 170 ° C. for 60 minutes and cut into 25 mm × 25 mm samples. The sample was floated in a solder bath at 260 ° C. for 60 seconds, taken out, and then observed for any change in appearance. Those with no change in appearance such as shrinkage were accepted.

The above results are shown in Table 2.

<Discussion>
As is clear from the results in Table 2, the films obtained in Examples 1 to 12 were uniform and were good in all of adhesion, elongation, and solder heat resistance as compared with Comparative Examples.

On the other hand, no elongation was obtained in the films of Comparative Example 1 in which the molecular weight of the polyol resin used was too small and Comparative Example 7 in which the polynol resin was not used. Further, even in the film of Comparative Example 3 in which the hydroxyl value of the polyol resin used was too large, no elongation was obtained.

Further, the films of Comparative Example 2 in which the hydroxyl value of the polyol resin used was too small and Comparative Example 6 in which the epoxy resin was not used did not provide sufficient heat resistance.

The films obtained in Examples 1 to 12 and Comparative Examples 1 to 3 and 5 to 7 were transparent, but in Comparative Example 4, the varnish solubility was poor, and neither the film nor the turbidity was compatible. No further evaluation has been done. Further, in Comparative Example 5, air was introduced during laminating due to the stickiness of the adhesive film, and uniform laminating could not be performed, so that the subsequent evaluation was not performed.

Claims (4)

30 to 80% by mass of a polyol resin having a weight average molecular weight of 100,000 to 1,000,000 and a hydroxyl value of 60 mgKOH / g to 110 mgKOH / g.
A thermosetting adhesive film containing at least 10 to 50% by mass of a solid epoxy resin and 10 to 50% by mass of an acid anhydride. The thermosetting adhesive film according to claim 1, wherein the solid epoxy resin has a softening point of 40 ° C. or higher and a weight average molecular weight of 800 or higher. The thermosetting adhesive film according to claim 1 or 2, wherein the acid anhydride has an equivalent of 200 or more and a number average molecular weight of 400 or more. A film obtained by curing the thermosetting adhesive film according to any one of claims 1 to 3.