JPH0759617B2 - Method for producing high molecular weight epoxy resin - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a high molecular weight epoxy resin used for adhesives, insulating materials, paints, molded products, films and the like.

[Conventional technology]

A method for producing a high molecular weight epoxy resin from a relatively low molecular weight difunctional epoxy resin and a bifunctional phenol as a raw material is generally called a two-step method, and the first document relating to this method is Japanese Patent Publication No. is there. In this publication, sodium hydroxide is used as a polymerization catalyst, and the solvent is 150-200 without solvent.
A high molecular weight epoxy resin having an epoxy equivalent of 5,600 is obtained by reacting at ℃. The average molecular weight of this resin can be estimated to be about 11,000.

Documents using a lithium compound as a polymerization catalyst include JP-B-37-3394 and JP-B-38-334.
In the production methods described in these, the molecular weight 1
No more than 0,000 resins have been obtained.

Documents using a phosphonium salt as a polymerization catalyst include JP-B-50-5760, JP-B-52-19878, and JP-A-5-19878.
0-110499, JP-A-54-52200, JP-A-58-
185611, JP-A-60-118757, JP-A-60-14
There are 4323 and JP-A-60-114324. Among the production methods described in these, those having obtained a high molecular weight epoxy resin include those disclosed in JP-A-54-52200, JP-A-60-118757, and JP-A-60-144323. , JP-A-60-114324. In any of these methods, the polymerization reaction is carried out in a solvent.

However, according to the examples described in these publications, the resin solid content concentration in the reaction solvent is 40% by weight at the lowest. The present inventors have confirmed that when the solid content concentration during the reaction is such high, branching occurs due to a side reaction and a linear high molecular weight epoxy resin is not produced. In particular, JP-A-60-144323 and JP-A-60-11
The weight average molecular weight as shown in 4324 publication is 100,
It has been confirmed by the present inventors that the ultra-high molecular weight epoxy resin of about 000 has a film-forming ability when it is linear, but it is disclosed in JP-A-60-144323 and JP-A-60-114324.
In the publication, there is no description to the effect that it has a film forming ability.

That is, it is clear that the conventional method for producing a high molecular weight epoxy resin could not obtain a linear epoxy resin having a high molecular weight until it had a film-forming ability.

[Problems to be Solved by the Invention]

An object of the present invention is to provide a method for producing an ultra-high molecular weight epoxy resin which has a high molecular weight until it has a film forming ability.

[Means for Solving the Problems]

The method for producing a high molecular weight epoxy resin of the present invention is a method for producing a high molecular weight epoxy resin by heating a bifunctional epoxy resin and a bifunctional phenol in a polymerization reaction solvent in the presence of a catalyst to polymerize the bifunctional epoxy resin. It is characterized in that the compounding equivalent ratio of the epoxy resin and the bifunctional phenol is set to epoxy group / phenolic hydroxyl group = 1: 0.9 to 1.1 and an alkylphosphorus catalyst in an amide solvent is used.

Hereinafter, the present invention will be described in detail.

The bifunctional epoxy resin in the present invention may be any compound having two epoxy groups in the molecule, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, Alicyclic epoxy resin, aliphatic chain epoxy resin, diglycidyl ether of bifunctional phenols,
There are diglycidyl ether compounds of difunctional alcohols, halides thereof, hydrogenated products thereof, and the like. The molecular weight of these compounds may be any. Several kinds of these compounds can be used in combination. Further, components other than the bifunctional epoxy resin may be included as impurities.

The bifunctional phenol in the present invention may be any compound as long as it has two phenolic hydroxyl groups, and examples thereof include monocyclic bifunctional phenols such as hydroquinone, resorcinol, catechol, and polycyclic bifunctional phenols. Examples include bisphenol A, bisphenol F, their halides, and alkyl group-substituted products. The molecular weight of these compounds may be any. Several kinds of these compounds can be used in combination. Further, components other than the bifunctional phenols may be included as impurities.

The alkylphosphorus catalyst in the present invention may be any compound having a catalytic ability to promote the etherification reaction of the epoxy group and the phenolic hydroxyl group,
Examples include tri-n-propylphosphine and tri-n-butylphosphine. These catalysts can be used in combination. Further, it may be used in combination with other catalysts represented by alkali metal type and imidazole type.

The polymerization reaction solvent in the present invention is preferably an amide-based solvent that dissolves the raw material epoxy resin and phenols. Examples of the amide solvent include formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N, N, N ′, N′-tetramethylurea, 2 -Pyrrolidone, N-methylpyrrolidone and the like. These solvents can be used in combination. Further, it may be used in combination with other solvent such as ether type.

As the production conditions in the present invention, the compounding equivalent ratio of the bifunctional epoxy resin and the bifunctional phenol is set to epoxy group / phenolic hydroxyl group = 1: 0.9 to 1.1. If the amount is less than 0.9 equivalent, the polymer does not linearly increase in molecular weight, a side reaction occurs and crosslinks, and the resin becomes insoluble in the solvent. If the amount is more than 1.1 equivalents, the high molecular weight resin will not proceed.

The amount of the catalyst to be blended is not particularly limited, but generally 0.0001 to 0.2 mol of the catalyst is used with respect to 1 mol of the bifunctional epoxy resin. If the amount is less than this range, the high molecular weight reaction is remarkably slow, and if it is more than this range, side reactions increase and the molecular weight may not linearly increase.

The synthesis reaction temperature during production is preferably 60 to 150 ° C. If the temperature is lower than 60 ° C, the high molecular weight reaction is extremely slow, and
If the temperature is higher than 0 ° C, side reactions may increase and the molecular weight may not linearly increase.

The solid content concentration in the synthetic reaction at the time of production may be 50% (% by weight, the same applies hereinafter) or less, but preferably 30% or less. When the concentration is higher than this range, side reactions increase and it becomes difficult to form a linear high molecular weight compound. Therefore,
When the polymerization reaction is carried out at a relatively high concentration and a linear high molecular weight epoxy resin is to be obtained, the reaction temperature may be lowered and the catalyst amount may be reduced.

The high molecular weight epoxy resin obtained by the present invention is an ultra high molecular weight epoxy resin having film forming ability, and has less branching as compared with the conventional high molecular weight epoxy resin,
It is considered that the polymer has a higher molecular weight and has a film forming ability with sufficient strength. The obtained film has properties that cannot be realized by a film formed using a conventional high molecular weight epoxy resin. That is, the strength is remarkably large and the elongation is remarkably large.

Another feature of the present invention is that by using an alkyl phosphorus compound as a polymerization reaction catalyst, the polymerization reaction using a solvent proceeds rapidly.

〔Example〕

Hereinafter, the present invention will be described in detail based on examples, but the present invention is not limited thereto.

Example 1 177.5 g of bisphenol A type epoxy resin (epoxy equivalent: 177.5) as a bifunctional epoxy resin and bisphenol A (hydroxyl equivalent: 115.5) as a bifunctional phenol 115.5
g, 4.81 g of tri-n-propylphosphine as an etherification catalyst was dissolved in 694.9 g of N, N-methylacetamide,
The solid content concentration in the reaction system was 30%. While mechanically stirring this, keep the temperature in the reaction system at 1 ° C in an oil bath at 110 ° C.
It was kept at 00 ° C and kept as it was for 24 hours. As a result, a high molecular weight epoxy resin solution having a viscosity of 1,331 mPa · s was obtained. The weight average molecular weight of this epoxy resin was 72,000 as measured by gel permeation chromatography and 55,000 as measured by light scattering method. The reduced viscosity of this dilute solution of high molecular weight epoxy resin (N, N-dimethylacetamide, 30 ° C, the same below) is 0.750 (dl /
g). This high molecular weight epoxy resin solution was applied to a glass plate and dried at 200 ° C. for 1 hour to obtain an epoxy resin film having a thickness of 30 μm. This film has a tensile strength of 34.3MPa, an elongation of 43.3% and a tensile modulus of 415MPa.
Met. The glass transition temperature is 100 ° C and the thermal decomposition temperature is 3.
It was 47 ° C.

Example 2 177.5 g of bisphenol A type epoxy resin (epoxy equivalent: 177.5) as a bifunctional epoxy resin and bisphenol A (hydroxyl equivalent: 115.5) as a bifunctional phenol 115.5
g, tri-n-butylphosphine as an etherification catalyst
6.07 g was dissolved in N, N-dimethylacetamide 697.8 g,
The solid content concentration in the reaction system was 30%. While mechanically stirring this, keep the temperature in the reaction system at 1 ° C in an oil bath at 110 ° C.
It was kept at 00 ° C and kept as it was for 24 hours. As a result, a high molecular weight epoxy resin solution having a viscosity of 1,152 mPa · s was obtained. The weight average molecular weight of this epoxy resin was 89,000 as a result of measurement by gel permeation chromatography, and 65,000 as a result of measurement by a light scattering method. The reduced viscosity of the dilute solution of the high molecular weight epoxy resin was 0.842 (dl / g). This high molecular weight epoxy resin solution is applied to a glass plate and dried at 200 ° C for 1 hour,
An epoxy resin film having a thickness of 35 μm was obtained. The tensile viscosity of this film was 26.5 MPa, the elongation was 44.3%, and the tensile elastic modulus was 400 MPa. The glass transition temperature is 102.
℃, the thermal decomposition temperature was 350 ℃.

Example 3 173.2 g of a bisphenol A type epoxy resin (epoxy equivalent: 173.2) as a bifunctional epoxy resin, 55.3 g of hydroquinone (hydroxyl group equivalent: 55.3) as a bifunctional phenol, and tri-n-propylphosphine 4.81 g as an etherification catalyst.
Was dissolved in 933.2 g of N, N-dimethylacetamide to adjust the solid content concentration in the reaction system to 20%. While mechanically stirring this, keep the temperature in the reaction system at 120 ° C in an oil bath at 125 ° C.
And kept for 12 hours. As a result, the viscosity is 1.
A high molecular weight epoxy resin solution of 920 mPa · s was obtained. The weight average molecular weight of this epoxy resin was 108,000 as measured by gel permeation chromatography and 87,500 as measured by light scattering method. The reduced viscosity of a dilute solution of this high molecular weight epoxy resin is 0.890.
(Dl / g). This high molecular weight epoxy resin solution is applied to a glass plate and dried at 200 ° C for 1 hour to give a thickness of 28 μm.
The epoxy resin film of was obtained. This film has a tensile strength of 36.7 MPa, an elongation of 43.2% and a tensile modulus of 392.
It was MPa. The glass transition temperature was 78 ° C and the thermal decomposition temperature was 348 ° C.

Example 4 173.2 g of bisphenol A type epoxy resin (epoxy equivalent: 173.2) as a bifunctional epoxy resin, 55.3 g of hydroquinone (hydroxyl equivalent: 55.3) as a bifunctional phenol, and tri-n-butylphosphine 6.07 g as an etherification catalyst.
It was dissolved in 938.3 g of N, N-dimethylformamide, and the solid content concentration in the reaction system was set to 20%. While mechanically stirring this, the temperature in the reaction system was kept at 120 ° C. in an oil bath at 125 ° C. and kept as it was for 12 hours. As a result, the viscosity is 2,17
A high molecular weight epoxy resin solution of 6 mPa.s was obtained. The weight average molecular weight of this epoxy resin was 112,000 as measured by gel permeation chromatography and 89,500 as measured by light scattering method. The reduced viscosity of this dilute solution of high molecular weight epoxy resin is 0.925 (dl /
g). This high molecular weight epoxy resin solution was applied to a glass plate and dried at 200 ° C. for 1 hour to obtain an epoxy resin film having a thickness of 33 μm. This film has a tensile strength of 42.2MPa, an elongation of 49.0% and a tensile modulus of 375MPa.
Met. The glass transition temperature is 79 ° C and the thermal decomposition temperature is 35.
It was 0 ° C.

Example 5 173.2 g of a bisphenol A type epoxy resin (epoxy equivalent: 173.2) as a bifunctional epoxy resin, 55.4 g of resorcinol (hydroxyl equivalent: 55.4) as a bifunctional phenol, and tri-n-propylphosphine 4.81 as an etherification catalyst.
g was dissolved in 544.6 g of N, N-dimethylacetamide to adjust the solid content concentration in the reaction system to 30%. While mechanically stirring this, keep the temperature in the reaction system at 110 ° C in an oil bath at 115 ° C.
And kept for 20 hours. As a result, the viscosity is 1.
A high molecular weight epoxy resin solution of 306 mPa · s was obtained. The weight average molecular weight of this epoxy resin was 92,000 as a result of measurement by gel permeation chromatography and 79,000 as a result of measurement by a light scattering method. The reduced viscosity of a dilute solution of this high molecular weight epoxy resin is 0.812 (d
l / g). This high molecular weight epoxy resin solution was applied to a glass plate and dried at 200 ° C. for 1 hour to obtain an epoxy resin film having a thickness of 30 μm. The tensile strength of this film is 38.2MPa, the elongation is 52.0%, the tensile modulus is 435MP.
It was a. The glass transition temperature is 80 ° C and the thermal decomposition temperature is 3.
It was 45 ° C.

Example 6 173.2 g of bisphenol A type epoxy resin (epoxy equivalent: 173.2) as a bifunctional epoxy resin, 55.4 g of resorcinol (hydroxyl equivalent: 55.4) as a bifunctional phenol, and tri-n-butylphosphine 6.07 g as an etherification catalyst.
Was dissolved in 547.6 g of N, N-dimethylformamide to adjust the solid content concentration in the reaction system to 30%. While mechanically stirring this, keep the temperature in the reaction system at 110 ° C in an oil bath at 115 ° C.
And kept for 20 hours. As a result, the viscosity is 1.
A high molecular weight epoxy resin solution of 740 mPa · s was obtained. The weight average molecular weight of this epoxy resin was 92,000 as a result of measurement by gel permeation chromatography and 83,000 as a result of measurement by a light scattering method. The reduced viscosity of this dilute solution of high molecular weight epoxy resin is 0.785.
(Dl / g). This high molecular weight epoxy resin solution is applied to a glass plate and dried at 200 ° C for 1 hour to give a thickness of 30 μm.
The epoxy resin film of was obtained. This film has a tensile strength of 32.2 Mpa, an elongation of 46.0% and a tensile modulus of 395.
It was MPa. The glass transition temperature was 78 ° C and the thermal decomposition temperature was 340 ° C.

Comparative Example 1 The compounding amount of bisphenol A in Example 1 was changed from 115.5 g (1.00 equivalent to the epoxy resin) to 80.9 g (0.70 equivalent to the epoxy resin), and the compounding amount of N, N-dimethylacetamide was 694.9 g. Example 1 was repeated except that the amount was changed to 614.2 g. As a result, it gelated after 1 hour and became insoluble in the solvent.

Comparative Example 2 The compounding amount of bisphenol A in Example 1 was changed from 115.5 g (1.00 equivalent to the epoxy resin) to 80.9 g (0.70 equivalent to the epoxy resin), and the compounding amount of N, N-dimethylacetamide was 694.9 g. The procedure of Example 1 was repeated except that the amount was changed to 614.2 g, but heating was stopped before gelation to obtain a high molecular weight epoxy resin solution having a viscosity of 620 mPa · s. The weight average molecular weight of the obtained resin was 72,000 as a result of measurement by gel permeation chromatography and 58,000 as a result of measurement by a light scattering method. The reduced viscosity of a dilute solution of this high molecular weight epoxy resin is 0.495 (dl /
g). This high molecular weight epoxy resin was applied to a glass plate and dried at 200 ° C. for 1 hour, but an epoxy resin film of 100 μm or less having sufficient strength for handling was not obtained.

Comparative Example 3 The procedure of Example 1 was repeated, except that N, N-dimethylacetamide in Example 1 was changed to methyl ethyl ketone, but the viscosity after 24 hours from the start of heating was 1.9 mPa · s. The weight average molecular weight of the obtained resin is 1,800 in the result measured by gel permeation chromatography,
It could not be measured by the light scattering method. This high molecular weight epoxy resin was applied to a glass plate and dried at 200 ° C for 1 hour.
No epoxy resin film was obtained.

Comparative Example 4 The procedure of Example 2 was repeated, except that the tri-n-butylphosphine in Example 2 was changed to boron trifluoride-methanol complex salt, but the viscosity after 24 hours from the start of heating was 3.8 m.
It was Pa · s. The weight average molecular weight of the obtained resin was 4, in the result measured by gel permeation chromatography.
It was 800 and could not be measured by the light scattering method. This high molecular weight epoxy resin was applied to a glass plate and dried at 200 ° C. for 1 hour, but an epoxy resin film of 100 μm or less showing sufficient strength in handling was not obtained.

Comparative Example 5 The procedure of Example 2 was repeated except that benzimidazole was used instead of tri-n-butylphosphine in Example 2, but the viscosity after heating for 24 hours was 10.2 mPa · s. The weight average molecular weight of the obtained resin was 7,800 as measured by gel permeation chromatography, and could not be measured by the light scattering method. This high molecular weight epoxy resin was applied to a glass plate and dried at 200 ° C. for 1 hour, but an epoxy resin film of 100 μm or less showing sufficient strength in handling was not obtained.

Comparative Example 6 The average molecular weight of phenoxy resin YP50P (Toto Kasei), which is a high molecular weight epoxy resin, was measured. The weight average molecular weight calculated as styrene by gel permeation chromatography was 77,000. The reduced viscosity of this dilute solution of phenoxy resin was 0.488 (dl / g). The resin dissolved readily in methyl ethyl ketone. Also, cyclohexanone 20%
The solution viscosity was 205 mPa · s. This high molecular weight epoxy resin solution was coated on a glass plate and heated and dried in a dryer to try to prepare an epoxy resin film.
A film having a thickness of 0 μm or less was not obtained.

Details of the experimental methods in the above Examples and Comparative Examples are shown below.

The viscosity was measured using an EMD viscometer (Tokyo Keiki). The column used for gel permeation chromatography (GPC) is TSKgel G6000 + G5000 + G4000 + G3000 + G2000. N, N-dimethylacetamide was used as the eluent, and the sample concentration was 2%. After the relationship between the molecular weight and the elution time was obtained using styrene having various molecular weights, the molecular weight was calculated from the elution time to obtain the styrene-equivalent weight average molecular weight. As the light scattering photometer, DLS-700 manufactured by Otsuka Electronics Co., Ltd. was used. Tensilon manufactured by Toyo Baldwin was used for tensile strength, elongation, and tensile elasticity. The film sample size was 50 × 10 mm, and the pulling speed was 5 mm / min. Glass transition temperature (Tg) is 910 type differential scanning calorimeter (DSC) manufactured by DuPont
Was measured using. The thermal decomposition temperature was determined by using a differential thermal balance TGD-3000 manufactured by Vacuum Riko Co., Ltd. as the temperature at which the weight loss started in the air.

As shown in Comparative Examples 1 and 2, when the compounding equivalent of the epoxy resin is excessive, it is considered that there is a large amount of branching, and although the molecular weight is considerably higher than 70,000, it is a film of 100 μm or less. Could not be molded.

In addition, as shown in Comparative Example 6, a commercially available phenoxy resin, which is a bisphenol A type ultra high molecular weight epoxy resin, was dissolved in methyl ethyl ketone even though it had a considerably high molecular weight, and the viscosity of a 20% cyclohexanone solution was increased. Was significantly lower than the viscosity of the ultra high molecular weight epoxy resin solution of the present invention. For these resins, 100μ
A film of m or less could not be formed.

When the reaction was stopped halfway and the epoxy resin having a relatively low molecular weight was used in the same formulation as in Example 1, the film could be molded, but the strength was remarkably low.

In all of the examples, as compared with the comparative example, an epoxy resin film having a thickness of 100 μm or less and having sufficient strength is obtained.

〔The invention's effect〕

According to the method for producing a high molecular weight epoxy resin of the present invention, an ultrahigh molecular weight epoxy capable of forming a sufficiently thin epoxy resin film having a sufficient strength of 100 μm or less, further 50 μm or less, which has not been obtained conventionally. It becomes possible to produce a resin, and this ultra high molecular weight epoxy resin can be obtained in a short time.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masami Arai, 1500 Ogawa, Shimodate, Shimodate, Ibaraki, Shimodate Research Laboratory, Hitachi Chemical Co., Ltd. (72) Ikuo Hoshi, 1500, Ogawa, Shimodate, Ibaraki, Hitachi Chemical Co., Ltd. Shimodate Laboratory (56) Reference JP-A-53-98399 (JP, A) JP-A-57-179219 (JP, A) JP-A-58-149914 (JP, A) JP-A-60-262819 (JP, A) JP-A-1-254733 (JP, A)

Claims (1)

[Claims] 1. A bifunctional epoxy resin and a bifunctional phenol are polymerized by heating in a polymerization reaction solvent in the presence of a catalyst,
In the method for producing a high molecular weight epoxy resin, the compounding equivalent ratio of the bifunctional epoxy resin and the bifunctional phenols is set to epoxy group / phenolic hydroxyl group = 1: 0.9 to 1.1, in an amide solvent, using an alkyl phosphorus catalyst, The solid content concentration at the time of the polymerization reaction is 50% by weight or less and is polymerized, which does not dissolve in methyl ethyl ketone and has a reduced viscosity of 0.6 dl / g.
(30 ° C., N, N-dimethylacetamide) or higher, a method for producing a high molecular weight epoxy resin.