JP2669217B2 - Flame retardant epoxy film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame-retardant epoxy film having excellent properties such as adhesiveness, heat resistance, moisture resistance and chemical resistance.

[0002]

2. Description of the Related Art A high molecular weight epoxy polymer obtained by polymerizing epihalohydrin and halogenated bifunctional phenols,
Further, a flame-retardant epoxy film using any one of a high-molecular-weight epoxy polymer obtained by polymerizing a low-molecular-weight epoxy resin and a halogenated bifunctional phenol is not found in patents and literatures.

References relating to halogenated linear high molecular weight epoxy polymers include US Pat. No. 3,277,048. This is a molecular weight of 3 obtained by reacting a bifunctional epoxy resin with brominated or chlorinated bisphenol.
The purpose is to obtain a flame-retardant epoxy resin cured product having good mechanical properties by blending 0000 or more thermoplastic resins. The molecular weight of the polymer obtained in the examples was 61,0
00, but there is no description of the measurement method. The thickness of the obtained sheet is 0.125 inch,
That is, it is about 3 mm. Furthermore, no solvent was used during the synthesis.

[0004] A method for producing a high-molecular-weight epoxy polymer from a relatively low-molecular-weight bifunctional epoxy resin and a bifunctional phenol is generally referred to as a two-stage method, and the first document relating to this method is disclosed in US Pat. No. 615,008, and in Japan, there is Japanese Patent Publication No. 28-4494 by the same applicant. In this document, sodium hydroxide is used as a polymerization catalyst, and 150 to 2
By reacting at 00 ° C., the epoxy equivalent becomes 5,6.
00 high molecular weight epoxy polymer is obtained. The average molecular weight of this polymer can be estimated to be about 11,000.
In these documents, there is no example using a solvent.

[0005] An example of a document describing the use of solvents is US Patent 3,306,872. Patents which use solvents in the examples include JP-A-54-5200 and JP-A-60-11.
8757, JP-A-60-144323 and JP-A-60-144324. Solvents used in these documents include methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether and the like. These solvents are classified into ketone type and ether type (cellosolve type) solvents.

In the description of US Pat. No. 3,306,872, either methyl ethyl ketone or ethylene glycol monomethyl ether is used as a solvent, and the solution has a solid content of 20 to 60%. As a catalyst, an alkali metal or benzyltrimethylammonium,
A hydroxide or phenolate is used. The polymerization reaction temperature is 75 to 150 ° C., and the produced high molecular weight epoxy polymer has a weight average molecular weight of at least 4
The reaction continues until it reaches over 50,000. The average molecular weight is determined by a viscosity method and is in the range of 50,000 to 1,0.
It has been measured as 0,000. However, it is known that the calculated value greatly depends on the setting of the parameters used in the calculation in the viscosity method. Therefore, it is not an accurate molecular weight measurement method.

An example in which a high molecular weight epoxy polymer is considered to be obtained by polymerization in a solvent is disclosed in Japanese Patent Application Laid-Open No. 54-52200, using ethylene glycol monoethyl ether as a solvent. It is described that a high molecular weight epoxy polymer having a molecular weight of 45,500 was obtained. In Japanese Patent Application Laid-Open No. 60-118575, methyl isobutyl ketone, cyclohexanone, and ethylene glycol monoethyl ether are used as solvents.
A high molecular weight epoxy polymer having an average molecular weight of at most 31,000 is obtained. JP-A-60-144323 discloses that
Using methyl ethyl ketone as the solvent, the average molecular weight was 53,
JP-A-60-144324 describes that a high molecular weight epoxy polymer having an average molecular weight of 66,000 was obtained using methyl ethyl ketone as a solvent. I have. The above four documents all measure the average molecular weight by gel permeation chromatography, but do not describe the measurement conditions, the calculation method, and the like. The molecular weight obtained by gel permeation chromatography depends on the type of filler used,
It varies greatly depending on the measurement conditions such as the type of eluent, the calculation method, and the like, and it is difficult to obtain an accurate value, and it cannot be said that an accurate average molecular weight is always measured.

[0008] None of the above-mentioned documents describes the fact that it has a film-forming ability, and there is no example. Also, because it is soluble in solvents other than amides,
It is clear that a high-molecular-weight epoxy polymer having a high-molecular-weight linearity has not been obtained until the film has sufficient strength to form a film.

A method for producing an epoxy resin sheet using a high molecular weight epoxy polymer is disclosed in
No. 87560. That is, the linear high molecular weight epoxy polymer and the low molecular weight epoxy resin are heated and melted, mixed with an organic carboxylate, and the thickness is
It is a method of obtaining a sheet of 0.3 to 0.5 mm. The properties of the obtained sheet are tensile strength of about 10 MPa and elongation of 3
It is 50 to 870%. The linear high molecular weight epoxy polymer used herein has a molecular weight of 30,000 to 250,000.
00 is set. The method of synthesizing the linear high molecular weight epoxy polymer has not been clarified. Moreover, the method for measuring the molecular weight is not described. In general, it is known that the average molecular weight measured by gel permeation chromatography varies greatly depending on measurement conditions. Although there is no restriction on the sheet thickness, it is considered that a sheet having a thickness of 300 μm or less cannot be obtained from the tensile strength of the sheet. Further, flame retardancy is not imparted to this sheet. Further, there is no example of an adhesive film in which a polyfunctional epoxy resin and a curing agent are mixed with an epoxy polymer having a film forming ability.

[0010]

In the prior art, a flame-retardant film based on an epoxy resin or an epoxy polymer having excellent properties such as heat resistance, moisture resistance, chemical resistance and adhesiveness is produced. I couldn't. Further, in the prior art, a film having a thickness of 100 μm or less, which is generally called a film or a thin film, cannot be produced for an epoxy film or an epoxy sheet.

[0011] The present invention provides a flame-retardant epoxy film which can be made as thin as 100 µm or less because of the high strength of the epoxy base film, and is excellent in adhesiveness, heat resistance, moisture resistance and chemical resistance. Is what you do.

[0012]

According to the present invention, there is provided a catalyst comprising a bifunctional epoxy resin and a halogenated difunctional phenol in an equivalent ratio of epoxy group / phenolic hydroxyl = 1: 0.9 to 1.1. A flame-retardant epoxy film characterized by using a high-molecular-weight epoxy polymer obtained by heating and polymerizing under a condition of a concentration of 50% by weight or less and a reaction temperature of 60 to 150 ° C. in an amide solvent. Things.

Hereinafter, the present invention will be described in detail. The bifunctional epoxy resin in the present invention may be any compound as long as it has two epoxy groups in a molecule. For example, bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin,
Alicyclic epoxy resin, aliphatic chain epoxy resin, other, diglycidyl etherified bifunctional phenols,
There are diglycidyl ethers of bifunctional alcohols, and halides and hydrogenated products thereof. These compounds can have any molecular weight. Some of these compounds can be used in combination. Further, components other than the bifunctional phenol resins may be contained as impurities.

The halogenated bifunctional phenol in the present invention may be any compound as long as the compound is substituted with a halogen atom and has two phenolic hydroxyl groups. For example, hydroquinone, which is a monocyclic bifunctional phenol, may be used. , Resorcinol, catechol, polycyclic bifunctional phenols such as bisphenol A, bisphenol F, naphthalene diols, biphenols and their alkyl group-substituted halides. These compounds can have any molecular weight. Some of these compounds can be used in combination. Further, components other than the bifunctional phenols may be contained as impurities.

The catalyst in the present invention may be any compound having a catalytic ability to promote the etherification reaction between an epoxy group and a phenolic hydroxyl group, such as an alkali metal compound, an alkaline earth metal compound, and the like. There are imidazoles, organophosphorus compounds, secondary amines, tertiary amines, quaternary ammonium salts and the like. Among them, alkali metal compounds are the most preferred catalysts. Examples of alkali metal compounds include sodium, lithium and potassium hydroxides, halides, organic acid salts, alcoholates, phenolates, hydrides, borohydrides, amides and the like. There is. These catalysts can be used in combination.

The amide solvent in the present invention may be any solvent as long as it dissolves the epoxy resin and the phenols as raw materials, and includes, for example, formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-amide. Methylacetamide, N, N-dimethylacetamide, N, N, N ', N'-tetramethylurea, 2-
Examples include pyrrolidone, N-methylpyrrolidone, and carbamic acid ester. These solvents can be used in combination. Further, it may be used in combination with other solvents represented by ketone solvents, ether solvents and the like.

The polymer synthesis conditions in the present invention include:
The compounding equivalent ratio of the bifunctional epoxy resin and the bifunctional phenol is: epoxy group / phenolic hydroxyl group = 1: 0.9-
1.1 is desirable. When the amount is less than 0.9 equivalent, a side reaction occurs without causing a high molecular weight in a linear form, resulting in crosslinking and insolubility in a solvent. If it is more than 1.1 equivalents, the high molecular weight does not progress.

The amount of the catalyst blended is not critical, but generally 0.0001 to 1 mol of the catalyst is added to 1 mol of the epoxy resin.
It is about 0.2 mol. When the amount is less than this range, the reaction for increasing the molecular weight is remarkably slow. Further, the polymerization reaction temperature is desirably 60 to 150 ° C. When the temperature is lower than 60 ° C., the reaction for increasing the molecular weight is remarkably slow, and when the temperature is higher than 150 ° C., side reactions increase and the molecular weight is not increased linearly.

The concentration at the time of the polymerization reaction using the solvent is 50%.
It is good if it is below, Preferably it is 40% or less. More preferably, it is desirable to make it 30% or less. As the concentration increases, side reactions increase and it becomes difficult to increase the molecular weight in a linear manner. Therefore, when a polymerization reaction is performed at a relatively high concentration and a linear high molecular weight epoxy resin is to be obtained, it is necessary to lower the reaction temperature and reduce the amount of the catalyst.

In the present invention, an adhesive film having excellent adhesiveness can be obtained by blending a polyfunctional epoxy resin and a curing agent thereof with the high molecular weight epoxy polymer. The polyfunctional epoxy resin used in the present invention,
Any compound may be used as long as it has two or more epoxy groups in the molecule. For example, bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, phenol novolak epoxy resin, cresol novolak Type epoxy resin, bisphenol A novolac type epoxy resin, bisphenol F novolac type epoxy resin, alicyclic epoxy resin, aliphatic chain type epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, hydantoin type epoxy resin, isocyanurate Epoxy resins, diglycidyl ether compounds of bifunctional phenols, diglycidyl ether compounds of bifunctional alcohols, and halides and hydrogenated products thereof. These compounds can have any molecular weight. Some of these compounds can be used in combination. Further, components other than the bifunctional epoxy resin may be contained as impurities.

Further, any curing agent may be used as long as it cures the ethoxy resin. Representative examples thereof include polyfunctional phenols, amines, imidazole compounds, and acid anhydrides.

Examples of polyfunctional phenols include monocyclic bifunctional phenols such as hydroquinone, resorcinol,
Examples include catechol, polyphenol bifunctional phenols such as bisphenol A, bisphenol F, naphthalene diols, biphenols, and halides and alkyl group-substituted products thereof. Further, there are novolaks and resols which are polycondensates of these phenols and aldehydes.

Examples of amines include aliphatic primary, secondary and primary amines.
And tertiary amines, aromatic primary and secondary tertiary amines, guanidines, urea derivatives, and the like. Specific examples include triethylenetetramine, diaminodiphenylmethane, diaminodiphenylether, dicyandiamide, tolylbiguanide, and guanylurea. And dimethyl urea.

Examples of the imidazole compound include alkyl group-substituted imidazole and benzimidazole. Examples of the acid anhydride include phthalic anhydride, hexahydrophthalic anhydride, pyromellitic dianhydride, benzophenonetetracarboxylic dianhydride and the like.

If desired, a curing accelerator may be added. Representative curing accelerators for epoxy resins include tertiary amines, imidazoles, and quaternary ammonium salts.

If desired, flame retardants, inorganic fillers and the like may be added. Flame retardants include bromine compounds such as tetrabromobisphenol A, decabromodiphenyl ether, brominated epoxy resins and brominated phenol resins, and metal hydroxides such as aluminum hydroxide and magnesium hydroxide. Further, if necessary, an arbitrary amount of a solvent other than the synthesis solvent may be added. These high molecular weight epoxy polymers, polyfunctional epoxy resins, curing agents, and curing accelerators may be mixed by any method.

The solvent can be removed by heating or drying under reduced pressure. The drying temperature may be any number as long as it is lower than the decomposition temperature of the high molecular weight epoxy polymer (about 320 ° C.). The atmosphere during drying is nitrogen, argon,
An inert gas such as helium or air is preferred. The pressure in the drying under reduced pressure may be any level as long as it is lower than the atmospheric pressure, but is preferably 20 kPa or less. After replacing the synthesis reaction solvent with another solvent, the solvent may be removed by the above-described method. These solvent removal methods can be used in combination.

The halogenated high molecular weight epoxy polymer having a film-forming ability of the present invention or the flame-retardant epoxy film obtained by blending a polyfunctional epoxy resin and a curing agent with the halogenated high molecular weight epoxy polymer is incompatible with a conventional epoxy adhesive film. It is possible to form a film having a thickness of 100 μm or less, which is possible, and has excellent flame retardancy. Further, it has the same or higher adhesiveness, heat resistance, chemical resistance, solvent resistance, and tensile strength. In addition, compared to the flame-retardant adhesive film using thermoplastic resin as the base adhesive film material, the flame-retardant adhesive film which has the advantages of epoxy resin such as heat resistance, moisture resistance, chemical resistance and adhesiveness. Can be obtained.

[0029]

The present inventors have determined that bisphenol A type epoxy resin and high molecular weight epoxy polymer made from bisphenol A are amide solvents when the weight average molecular weight in terms of styrene by gel permeation chromatography exceeds 100,000. It has been confirmed that it does not dissolve except for. When the weight average molecular weight in terms of styrene exceeds 100,000 and is dissolved in a solvent other than an amide solvent, it is also confirmed that the polymer is a highly branched high molecular weight epoxy polymer. For example, a high molecular weight epoxy polymer obtained by using a bisphenol A type epoxy resin and bisphenol A and polymerizing with an equivalent ratio of epoxy group / phenolic hydroxyl group of 1 / 0.60 to 1 / 0.80 has many branches. It is conceivable that the high molecular weight epoxy polymer having a weight average molecular weight of 110,000 in terms of styrene obtained at an equivalent ratio in this range dissolves in methyl ketone which is a ketone solvent. On the other hand, a high molecular weight epoxy polymer having a weight average molecular weight of 66,000 in terms of styrene polymerized in an amide-based solvent with an equivalent ratio of epoxy group / phenolic hydroxyl group of 1 / 0.99 to 1 / 1.01 is obtained. , Which is considered to be a linear high molecular weight epoxy polymer, but does not dissolve in methyl ethyl ketone. In order for the linear high molecular weight epoxy polymer to completely dissolve in methyl ethyl ketone, the weight average molecular weight in terms of styrene needs to be about 20,000 or less.

Although it is not possible at present to accurately measure the degree of branching of a linear polymer, if the molecular weight is the same, the longer the number of branches, the shorter the length of the linear portion, which affects various properties. It is thought to give. In terms of physical properties, it is considered to be sufficient to compare a thermoplastic resin of a linear polymer with a thermosetting resin that is a crosslinked polymer having many branches. Thermoplastic resins that are linear polymers generally have higher impact resistance and greater elongation than thermosetting resins.
As a result, most thermoplastics have sufficient strength to form films.

[0031]

The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples.

Example 1 A bisphenol A type epoxy resin (epoxy equivalent: 17) was used as a bifunctional epoxy resin.
1.5) 171.5 g, tetrabromobisphenol A as a bifunctional phenol (hydroxyl equivalent: 271.9)
271.9 g and 1.20 g of sodium hydroxide as an etherification catalyst were dissolved in 1037.4 g of N, N-dimethylacetamide, which is an amide solvent, to give a solid concentration of 30% in the reaction system. While mechanically stirring the mixture, the temperature in the reaction system was maintained at 120 ° C. in an oil bath, and was maintained for 6 hours. As a result, the viscosity was 6,200 mPa.
The reaction was saturated with s, and the reaction was completed. The weight average molecular weight of the obtained high molecular weight epoxy polymer was 258,000 as measured by gel permeation chromatography, and 121,000 as measured by light scattering.
The reduced viscosity of the diluted solution was 0.89 dl / g.

The obtained solution was applied to a glass plate and dried by heating in a dryer at 170 ° C. for 1 hour to remove the solvent, thereby obtaining a 28 μm thick flame-retardant epoxy film.
The film has a tensile strength of 58 MPa and a tensile elastic modulus of 2.5.
00 MPa, elongation was 12%, Tg was 123 ° C, and thermal decomposition temperature was 326 ° C. After exposing the film cut to 12.7 mm × 127 mm to the flame of a gas burner for 10 seconds, the film was kept away from the flame and burned for an average of 3 seconds.

Example 2 A high molecular weight epoxy polymer was prepared in the same manner as in Example 1 except that lithium hydroxide and 0.66 g were used instead of 1.20 g of sodium hydroxide as a catalyst in Example 1. I got The viscosity of a 30% solution of N, N-dimethylacetamide is 18,600 mPa.s.
s, The weight average molecular weight was 511,000 as measured by gel permeation chromatography, and 178,000 as measured by light scattering. The reduced viscosity of the diluted solution was 1.36 dl / g. In the same manner as in Example 1, a flame-retardant epoxy film having a thickness of 22 μm was obtained from the obtained high molecular weight epoxy polymer solution. The tensile strength of the film is 71 MPa, and the tensile elastic modulus is 2,70.
0 MPa, elongation was 21%, Tg was 126 ° C, and thermal decomposition temperature was 327 ° C. After exposing the film cut to 12.7 mm x 127 mm in the flame of a gas burner for 10 seconds, the film was kept away from the flame and burned for an average of 2 seconds.

Example 3 The procedure of Example 2 was repeated, except that N-methylpyrrolidone was used instead of N, N-dimethylacetamide as the reaction solvent in Example 2.
A high molecular weight epoxy polymer was obtained. The viscosity of a 30% solution of N-methylpyrrolidone is 10,300 mPa.s. s, The weight average molecular weight was 194,000 as measured by gel permeation chromatography, and 110,000 as measured by light scattering. The reduced viscosity of the diluted solution was 1.02 dl / g. From the obtained high molecular weight epoxy polymer solution, a thickness of 24 was obtained in the same manner as in Example 1.
A μm flame-retardant epoxy film was obtained. The film had a tensile strength of 65 MPa, a tensile modulus of 2,500 MPa, an elongation of 9%, a Tg of 125 ° C., and a thermal decomposition temperature of 325 ° C. After exposing the film cut to 12.7 mm × 127 mm to the flame of a gas burner for 10 seconds, the film was kept away from the flame and burned for an average of 3 seconds.

Example 4 A cresol novolak type epoxy resin (epoxy equivalent: 19) was added to the high molecular weight epoxy polymer solution obtained in Example 1 as a polyfunctional epoxy resin.
8) 146 g, 78 g of phenol novolak (hydroxyl equivalent: 106) as a curing agent, and 0.73 g of 2-ethyl-4-methylimidazole as a curing accelerator, and N, N-dimethylacetamide as a diluting solvent was added to adjust the concentration to 20. %, And then mechanically stirred for 1 h. The obtained varnish is applied on a glass plate and dried in a vacuum dryer at 100 ° C / 1
After drying under reduced pressure, a flame-retardant epoxy adhesive film having a thickness of 30 μm was obtained.

The flame-retardant epoxy adhesive film has a tensile strength of 60 MPa, a tensile modulus of 2,300 MPa and an elongation of 1
1%, Tg 92 ° C, softening point 85 ° C, pyrolysis temperature 3
22 ° C. After exposing the film cut to 12.7 mm x 127 mm in the flame of a gas burner for 10 seconds,
The burning time, away from the flame, averaged 3 seconds.

When the flame-retardant epoxy adhesive film was sandwiched between copper foils having a thickness of 35 μm and molded under the conditions of 170 ° C./10 min and 1 MPa, the peel strength of the copper foil was 1.6 kN / m. The Tg of the cured film was 135 ° C. No abnormality was found even when immersed in toluene, methylene chloride, 10% hydrochloric acid, and 10% aqueous sodium hydroxide for 30 minutes.

Example 5 A flame-retardant epoxy adhesive film having a thickness of 27 μm was obtained in the same manner as in Example 1, except that 4.5 g of dicyandiamide was used instead of phenol novolak as a curing agent in Example 4. The flame-retardant epoxy adhesive film has a tensile strength of 65 MPa and a tensile modulus of 2,20.
0 MPa, elongation 9%, Tg 75 ° C., softening point 89
℃, the thermal decomposition temperature was 311 ℃. The burning time measured in the same manner as in Example 1 was 6 seconds. The copper foil peel strength when molded in the same manner as in Example 1 is 2.1 kN / m
Met. The Tg of the cured film was 140 ° C. The solvent resistance and chemical resistance were also good.

Example 6 Phenol novolac, which is the curing agent in Example 4, was replaced with 2-phenylimidazole 3
A flame-retardant epoxy adhesive film having a thickness of 25 μm was obtained in the same manner as in Example 1 except that g was changed. The flame-retardant epoxy adhesive film has a tensile strength of 63 MPa and a tensile elastic modulus of 2,
300 MPa, elongation 8%, Tg 82 ° C., softening point 9
The temperature was 6 ° C, and the thermal decomposition temperature was 327 ° C. The burning time measured in the same manner as in Example 1 was 4 seconds. The copper foil peeling strength when molded in the same manner as in Example 1 is 1.8 kN /
m. The Tg of the cured film was 147 ° C. The solvent resistance and chemical resistance were also good. [Example 7]

The procedure of Example 4 was repeated, except that the high molecular weight epoxy polymer obtained in Example 2 was used.
A flame-retardant epoxy adhesive film of was obtained. The flame-retardant epoxy adhesive film has a tensile strength of 53 MPa and a tensile modulus of 1
900 MPa, elongation 7%, Tg 73 ° C., softening point 9
The temperature was 6 ° C and the thermal decomposition temperature was 328 ° C. The burning time measured in the same manner as in Example 1 was 2 seconds. The copper foil peeling strength when molded in the same manner as in Example 1 is 1.8 kN /
m. The Tg of the cured film was 140 ° C. The solvent resistance and chemical resistance were also good.

Example 8 The method of preparing an adhesive film in Example 4, after applying a varnish on a glass plate and then drying it in a vacuum dryer at 100 ° C. for 1 hour under reduced pressure, was replaced with a glass. After applying it to the plate, soak it in ethanol for 30 min, and then in a dryer at 80 ° C / 0.5
A thickness of 28 was obtained in the same manner as in Example 1 except that the material was heated and dried.
A μm flame-retardant epoxy adhesive film was obtained. The flame-retardant epoxy adhesive film had a tensile strength of 66 MPa, a tensile modulus of 2,400 MPa, an elongation of 17%, a Tg of 81 ° C, a softening point of 88 ° C, and a thermal decomposition temperature of 320 ° C. The combustion time measured in the same manner as in Example 1 was 3 seconds. The copper foil peeling strength when formed in the same manner as in Example 1 was 1.
It was 8 kN / m. The Tg of the cured film is 13
8 ° C. The solvent resistance and chemical resistance were also good.

Example 9 A flame-retardant epoxy adhesive film having a thickness of 20 μm was obtained in the same manner as in Example 4 except that 50 g of aluminum hydroxide was added as a flame retardant to the composition of Example 4. The flame-retardant epoxy adhesive film has a tensile strength of 62 MPa, a tensile elastic modulus of 2500 MPa, and an elongation of 10
%, Tg 84 ° C., softening point 92 ° C., thermal decomposition temperature 30
7 ° C. The burning time measured in the same manner as in Example 1 was 0 second. The copper foil peel strength when molded in the same manner as in Example 1 was 1.8 kN / m. The Tg of the cured film was 134 ° C. The solvent resistance and chemical resistance were also good.

Example 10 A brominated epoxy resin (epoxy equivalent: 400) which is a flame-retardant epoxy resin instead of the cresol novolak type epoxy resin in Example 4
Was prepared in the same manner as in Example 4 except that 300 g of
An 8 μm flame-retardant epoxy adhesive film was obtained. The flame-retardant epoxy adhesive film had a tensile strength of 70 MPa, a tensile elastic modulus of 2,600 MPa, an elongation of 9%, a Tg of 84 ° C., a softening point of 90 ° C., and a thermal decomposition temperature of 317 ° C. The burning time measured in the same manner as in Example 1 was 0 second. The copper foil peeling strength when formed in the same manner as in Example 1 was 1.
It was 9 kN / m. The Tg of the cured film is 13
8 ° C. The solvent resistance and chemical resistance were also good.

Comparative Example 1 The average molecular weight of phenoxy resin YP50P (Toto Kasei), which is a high molecular weight epoxy resin, was measured. The styrene-equivalent weight average molecular weight by gel permeation chromatography was 68,000, and the average molecular weight by light scattering was 58,000. The reduced viscosity of the diluted solution was 0.48 dl / g. This resin readily dissolved in methyl ethyl ketone. The viscosity of a 20% solution of N, N-dimethylacetamide is 200 mPa.s. s. The obtained varnish was applied to a glass plate, and dried in a dryer for 1 hour.
The solvent was removed by heating and drying at 70 ° C. for 1 hour, but an epoxy film having a thickness of 200 μm or less and a tensile strength of 10 MPa or more was not obtained.

Comparative Example 2 A high molecular weight epoxy polymer was obtained in the same manner as in Example 1, except that the reaction solvent N, N-dimethylacetamide used in Example 1 was changed to methyl isobutyl ketone. 30 of methyl isobutyl ketone
% Solution viscosity is 150 mPa.s. s, the weight average molecular weight is
38,000 according to the result measured by gel permeation chromatography, 2 according to the result measured by the light scattering method.
It was 1,000. The dilute solution has a reduced viscosity of 0.2.
It was 7 dl / g. An attempt was made to obtain a flame-retardant epoxy film from the obtained high-molecular-weight epoxy polymer solution in the same manner as in Example 1, except that a tensile strength of 200 μm or less was obtained.
An epoxy film of 0 MPa or more was not obtained.

Comparative Example 3

An epoxy adhesive film was obtained in the same manner as in Example 4, except that 271.9 g of tetrabromobisphenol A in Example 1 was replaced with 114.2 g of bisphenol A. The tensile strength of the epoxy adhesive film is 54
MPa, tensile elastic modulus is 2,100 MPa, elongation is 18
%, Tg is 85 ° C., softening point is 90 ° C., and thermal decomposition temperature is 32
It was 0 ° C. The burning time measured in the same manner as in Example 1 did not extinguish the fire until all the films burned. The copper foil peel strength when molded in the same manner as in Example 1 was 1.5 kN / m. The Tg of the cured film is
120 ° C. Toluene, 10% hydrochloric acid, 10%
There was no abnormality even when immersed in an aqueous solution of sodium hydroxide for 30 minutes. Details of the experimental methods in the above Examples and Comparative Examples are shown below. The phenol compounding equivalent is a compounding equivalent of phenols to 1.000 equivalent of the epoxy resin. The viscosity was measured using an EMD type viscometer (Tokyo Keiki). The column used for gel permeation chromatography (GPC) is TSKgel G6000 + G5000 +
It is G4000 + G3000 + G2000. N, N-dimethylacetamide was used as the eluent, and the sample concentration was 2%. After obtaining the relationship between the molecular weight and the elution time using styrene of various molecular weights, the molecular weight was calculated from the elution time, and the calculated weight average molecular weight was calculated as styrene.

The light scattering photometer is a DLS manufactured by Otsuka Electronics Co., Ltd.
-700 was used. The reduced viscosity of the diluted solution was measured using an Ubbelohde viscometer. For tensile strength, elongation and tensile modulus, Tensilon manufactured by Toyo Baldwin was used. The film sample size is 50 × 10 mm, and the tensile speed is 5 mm /
min. The glass transition temperature (Tg) was measured using a DuPont 910 differential scanning calorimeter (DSC).
The thermal decomposition temperature is the differential thermal balance TGD-300 manufactured by Vacuum Riko.
Using 0, the temperature at which weight loss started in air was defined as the thermal decomposition temperature.

As shown in Comparative Example 1, when a phenoxy resin which is a commercially available high molecular weight epoxy polymer was used,
Epoxy films of 200 μm or less could not be molded. Further, as shown in Comparative Example 2, even when methyl isobutyl ketone, which is a solvent other than the amide-based solvent, was used as a reaction solvent, an epoxy film of 200 μm or less could not be formed. Furthermore, as shown in Comparative Example 3, when no halogenated phenols are used as a raw material for synthesis, there is no self-extinguishing property.

[0051]

As described above, the flame-retardant epoxy film according to the present invention is sufficiently thin, has sufficient strength, heat resistance, adhesiveness, and chemical resistance. The value is great.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-56722 (JP, A) JP-A-1-304110 (JP, A) JP-A-62-279224 (JP, A) JP-B-38 20988 (JP, B1)

Claims (11)

(57) [Claims] 1. A bifunctional epoxy resin and a halogenated bifunctional phenol are mixed with epoxy group / phenolic hydroxyl group = 1:
At an equivalent ratio of 0.9 to 1.1, in the presence of a catalyst, in an amide-based solvent, the reaction solids concentration is 50% by weight or less, and the reaction temperature is 60 to
A flame-retardant epoxy film comprising a high molecular weight epoxy polymer obtained by heating and polymerizing at 150 ° C. 2. The flame-retardant epoxy film according to claim 1, wherein a polyfunctional epoxy resin and a curing agent are blended with the high molecular weight epoxy polymer. 3. The method according to claim 1, wherein the weight average molecular weight in terms of styrene of the high molecular weight epoxy polymer by gel permeation chromatography or the average molecular weight by light scattering method is 50,000 or more. Flammable epoxy film. 4. The flame-retardant epoxy film according to claim 1, wherein the reduced viscosity of the dilute solution of the high molecular weight epoxy polymer is 0.50 dl / g or more. 5. The flame-retardant epoxy film according to claim 1, wherein the reduced viscosity of the dilute solution of the high molecular weight epoxy polymer is 0.70 dl / g or more. 6. The flame-retardant epoxy film according to claim 1, wherein the obtained flame-retardant epoxy film having a thickness of 100 μm or less has a tensile strength of 10 MPa or more. 7. The flame-retardant epoxy film according to claim 1, wherein the reaction solvent for the high molecular weight epoxy polymer is N, N-dimethylacetamide. 8. The reaction solvent for the high molecular weight epoxy polymer is N
-The flame-retardant epoxy film according to claim 1, which is methylpyrrolidone. 9. The flame-retardant epoxy film according to claim 1, wherein the solid content concentration during the synthesis of the high molecular weight epoxy polymer is 30% or less. 10. The flame-retardant epoxy film according to claim 1, wherein the halogenated bifunctional phenol is brominated bisphenol A. 11. The flame-retardant epoxy film according to claim 2, wherein the curing agent is selected from the group consisting of polyfunctional phenols, amines, and imidazole compounds.