JPH07145221A - Production of glycidyl-etherified phenolic novolak resin - Google Patents

Abstract

PURPOSE:To obtain a glycidyl-etherified phenolic novolak resin having excellent heat resistance and low-water absorption, self-curing, simple in compounding, excellent in workability and useful as curing agaent, etc., by reacting a specific phenolic novolak resin with an allyl halide. CONSTITUTION:The objective resin is obrtained by reacting (A) a phenolic novolak resin having a number average molecular weight of 450-1000 and (B) an allyl halide and epoxidizing the allyl group with a paracid after the allyl- etherification of 20-80% of the OH group of the component A. Further, the reaction is preferably performed e.g. under the reaction conditions: a reaction temperature of 0-80 deg.C and a reaction of about 1-5hr.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a partially glycidyl etherified phenol novolac resin. More specifically, it relates to a method for producing a partially glycidyl etherified phenol novolac resin which has excellent heat resistance and low water absorption and can be self-cured.

[0002]

2. Description of the Related Art Epoxy resins have hitherto been used in various applications such as paints, laminated plates and electric / electronic materials. Further, the epoxy resin is generally used in combination with a curing agent, and particularly in the field of electric / electronic materials, a phenol novolac resin is preferably used as the curing agent because of its excellent heat resistance.

However, the phenol novolac resin reacts with the epoxy resin to form a network structure, and at that time, the phenolic hydroxyl groups that do not participate in the reaction remain unreacted, so that they have a strong affinity with water and are generally used. It had a drawback that it had a high hygroscopicity. Therefore, when an epoxy resin composition using a phenol novolac resin as a curing agent is used as a sealing material or the like, there is a problem that the material is cracked due to the vapor pressure of water vaporized during mounting.
Further, the epoxy resin composition is a mixture of a phenol novolac resin and an epoxy resin, and the compounding requires high technology and quality control.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a phenol novolac resin which has excellent heat resistance and low water absorption and can be self-curable.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above problems, and as a result, partially glycidyl etherified phenol novolac obtained by glycidyl etherification of some of the hydroxyl groups of the phenol novolac resin. The inventors have found that a resin allows the glycidyl group and the phenolic hydroxyl group to react with each other intramolecularly or intermolecularly to self-cure to obtain a cured product having a small amount of residual phenolic hydroxyl group, and thus completed the present invention.

That is, the present invention has a number average molecular weight of 450.
~ 1000 phenol novolac resin and allyl halide are reacted to make 20-80% of the hydroxyl groups of the phenol novolac resin allyl etherified, and then the allyl group is epoxidized with peracid to form a partial glycidyl ether. The present invention relates to a method for producing a modified phenol novolac resin.

The partially glycidyl etherified phenol novolac resin obtained in the present invention is the one in which 20 to 80% of the hydroxyl groups of the phenol novolac resin are partially glycidyl etherified as described above. Preferably 35-6
5% is preferably glycidyl etherified. The glycidyl etherification rate of phenol novolac resin is 20
If it is less than%, the cross-linking density of the cured product becomes low, and heat resistance cannot be satisfied. On the other hand, when it exceeds 80%, the gelation rate becomes fast and the control of the curing rate becomes difficult, and therefore either case is not preferable.

The softening point of the partially glycidyl etherified phenol novolac resin obtained by the present invention is 70-1.
The temperature is about 20 ° C, preferably 80 to 100 ° C. 70 ° C
If it is less than 120 ° C, the heat resistance cannot be satisfied, and if it exceeds 120 ° C, the melt viscosity of the resin becomes high and the workability deteriorates.

The partially glycidyl etherified phenol novolac resin of the present invention has a number average molecular weight of 450 to 1
It can be produced by reacting 000 phenol novolac resin with allyl halide to 20 to 80% of the hydroxyl groups of the phenol novolac resin to allyl ether, and then epoxidizing the allyl group with peracid.

As the phenol novolac resin having a number average molecular weight of 450 to 1,000, known resins obtained by addition-condensing phenols and formaldehyde under acidic conditions can be used. For example, as phenols,
Phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol,
3,4-xylenol, 3,5-xylenol, p-ethylphenol, p-isopropylphenol, p-tert-butylphenol, p-octylphenol, nonylphenol, p-phenylphenol, p-
Examples thereof include chlorophenol and p-bromophenol, and these may be used alone or in combination of two or more kinds.
When the number average molecular weight of the phenol novolac resin is less than 450, the heat resistance cannot be sufficiently satisfied, and when it exceeds 1000, the melt viscosity becomes high and the workability deteriorates.
The softening point of the phenol novolac resin is preferably about 85 ° C. or higher. If the temperature is less than 85 ° C, the softening point of the partially glycidyl etherified phenol novolac resin will be low, and heat resistance will not be satisfied.

The allyl etherification of the known phenol novolac resin is carried out by reacting the hydroxyl group of the phenol novolac resin with an allyl halide having the above allyl etherification ratio in the presence of an alkali such as sodium hydroxide. To do. The amount of allyl halide used is preferably about 1.5 times the desired allyl etherification rate. The reaction is usually carried out in a solvent such as methyl isobutyl ketone at a reaction temperature of about 40 to 70 ° C.
The reaction time is 2 to 5 hours. The partially allyl etherified phenol novolac resin obtained is solvent-extracted, washed with water, and then concentrated before use. The softening point of the partially allyl etherified novolak is preferably about 50 ° C. or higher. If the softening point is less than 50 ° C., the partially glycidyl etherified phenol novolac resin will have a low softening point even if it is oxidized and epoxidized, and heat resistance cannot be satisfied.

Next, in the present invention, the allyl group of the partially allyl etherified phenol novolac resin is epoxidized with a peracid to produce a partially glycidyl etherified phenol novolac resin. Hydrogen peroxide solution as peracid,
Examples thereof include peracetic acid, perbenzoic acid, and metachloroperbenzoic acid. The amount of the peracid used is usually 1 to 1.2 molar equivalents of peracid with respect to 1 molar equivalent of allyl groups of the partially allyl etherified phenol novolac resin. . Such epoxidation is usually carried out in a solvent such as dichloroethane, dichloromethane or chloroform at a reaction temperature of about 0 to 80 ° C. for a reaction time of 1 to 5
Perform under the condition of time. The partially glycidyl etherified phenol novolac resin obtained is solvent-extracted and washed with water, or peracid is reduced with a reducing agent such as sodium thiosulfate and then washed with water.

The partially glycidyl etherified phenol novolac resin of the present invention thus obtained is usually used after adding a curing accelerator in order to accelerate the curing reaction. As the curing accelerator, for example, 1,8-diaza-bicyclo (5,5
4,0) tertiary amines such as undecene-7, triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, tris (dimethylaminomethyl) phenol; 2-methylimidazole, 2-phenylimidazole, 2-phenyl Imidazoles such as 4-methylimidazole and 2-heptadecylimidazole; organic phosphines such as tributylphosphine, methyldiphenylphosphine, triphenylphosphine, diphenylphosphine and phenylphosphine; tetraphenylphosphonium tetraphenylborate, 2-ethyl- Examples include tetraphenylboron salts such as 4-methylimidazole tetraphenylborate and N-methylmorpholine tetraphenylborate. . The amount of the curing accelerator used is 100% of the partially glycidyl etherified phenol novolac resin.
It is used in a proportion of 0.1 to 5 parts by weight with respect to parts by weight.
If the amount is less than 0.1 parts by weight, the effect of promoting curing is scarce, and if the amount exceeds 5 parts by weight, the cured product tends to impair properties such as heat resistance and mechanical properties, which is not preferable.

The partially glycidyl etherified phenol novolac resin of the present invention is self-curable, but a known phenol novolac resin or polyfunctional epoxy resin is used in combination within a range that does not adversely affect the performance of low water absorption. You can also Known phenol novolac resins include the phenol novolac resins exemplified above, and polyfunctional epoxy resins include orthocresol novolac type epoxy resins, phenol novolac type epoxy resins and other novolac resin type epoxy resins; bisphenol A, bisphenol F Glycidyl ester type epoxy resin obtained by reacting diglycidyl ether such as phthalic acid, polybasic acid such as dimer acid, and epichlorohydrin; reacting polyamine such as diaminodiphenylmethane, isocyanuric acid with epichlorohydrin Glycidyl amine type epoxy resins obtained include linear aliphatic epoxy resins and alicyclic epoxy resins obtained by oxidizing an olefin bond with a peracid such as peracetic acid.

In addition, a solvent, a filler, a release agent, a surface treatment agent, a flame retardant and the like may be added to the partially glycidyl etherified phenol novolac resin, if necessary.

[0016]

According to the present invention, a phenol novolac resin excellent in heat resistance and low water absorption can be provided. Further, the phenol novolac resin of the present invention is self-curing, easy to mix, and excellent in handleability.

[0017]

EXAMPLES The present invention will be described in more detail with reference to production examples, examples and comparative examples, but the present invention is not limited to these examples.

Production Example 1 After replacing the inside of a 1000 ml flask equipped with a stirrer, a thermometer and a condenser with nitrogen gas, 329 g of phenol
(3.5 mol), 236 g of 37% formalin aqueous solution
(2.9 mol) and 2.2 g of oxalic acid were added, and the mixture was refluxed under a nitrogen stream for 4 hours, dehydrated under reduced pressure, and dephenoled by steam distillation to obtain an unreacted phenol content of 0.5%. Hereafter, the softening point is 115 ° C. and the number average molecular weight is 65.
0, phenolic novolac resin 32 having a hydroxyl equivalent of 106
0 g was obtained. The phenol novolac resin is referred to as Compound A.

Production Example 2 After replacing the inside of a 1000 ml flask equipped with a stirrer, a thermometer and a condenser with nitrogen gas, orthocresol 37
8g (3.5mol), 37g formalin aqueous solution 131g
(1.6 mol), 92% paraformaldehyde 52.6
g (1.6 mol) and 2.2 g of oxalic acid were added, refluxed under a nitrogen stream for 3 hours, dehydrated under reduced pressure, and decresoled by steam distillation to obtain an unreacted cresol content of 0.5. % Or less, softening point 110 ° C., number average molecular weight 70
380 g of ortho-cresol novolac resin having 0 and a hydroxyl equivalent of 120 was obtained. The orthocresol novolak resin is referred to as Compound B.

Production Example 3 After replacing the inside of a 1000 ml flask equipped with a stirrer, a thermometer and a condenser with nitrogen gas, 329 g of phenol
(3.5 mol), 207 g of 37% formalin aqueous solution
(2.55 mol) and 1.3 g of oxalic acid were added, and the mixture was refluxed under a nitrogen stream for 3 hours, dehydrated under reduced pressure, and dephenoled by steam distillation to obtain an unreacted phenol content of 0.5%. Below, softening point 92 ℃, number average molecular weight 48
0, phenolic novolac resin 30 having a hydroxyl equivalent of 106
3 g was obtained. The phenol novolac resin is referred to as compound C.

Example 1 After replacing the inside of a 1000 ml flask equipped with a stirrer, a thermometer and a cooler with nitrogen gas, 106 g of compound A (hydroxyl equivalent 106) obtained in Preparation Example 1 and 200 g of methyl isobutyl ketone. Was added and dissolved. Then, 94.4 g of allyl bromide was added, and subsequently 100 g of a 24% aqueous sodium hydroxide solution was added dropwise over 1 hour, and then at 60 ° C. for 3 hours.
I kept it warm for an hour. Then, it was washed 5 times with 400 g of water, and the organic solvent layer was concentrated to obtain 136 g of resin. The resin was a semi-solid resin, and the allyl etherification rate was 60%. Then, 68 g of the semi-solid resin was added to dichloroethane 2
It was dissolved in 00 g, cooled to 10 ° C., and 57 g of metachloroperbenzoic acid was gradually added with stirring. After stirring at 10 ° C. for 2 hours, diluting with 1000 ml of ether, washing the solvent layer with aqueous sodium thiosulfate, washing thoroughly with water, and concentrating, softening point is 95 ° C., partial glycidyl etherification of epoxy equivalent 264 72 g of phenol novolac resin was obtained. The partially glycidyl etherified phenol novolac resin is referred to as Compound D.

Example 2 Compound B obtained in Production Example 2 was replaced with 106 g of Compound A (hydroxyl group equivalent 106) obtained in Production Example 1 in Example 1.
(Hydroxyl equivalent 120) The same procedure as in Example 1 except that 120 g was used, the softening point was 91 ° C, and the epoxy equivalent was 296.
80 g of partially glycidyl etherified phenol novolac resin of was obtained. The partially glycidyl etherified phenol novolac resin is referred to as Compound E.

(Test Example) Compound A or B obtained in the example or compound C obtained in Production Example 3 as a comparative example and an epoxy resin (ESCM195XL, manufactured by Sumitomo Chemical Co., Ltd., epoxy equivalent 198) Mixture and curing accelerator DBU (1,8-diaza-bicyclo (5,4,4
0) undecene-7) was blended in the proportions shown in Table 1 and cured at 175 ° C. for 10 hours to obtain a plate-shaped test piece having a thickness of 2 mm. The results of measuring the glass transition temperature and water absorption of the obtained cured product are shown in Table 1.

The glass transition temperature (Tg) was measured by using TMA120 manufactured by Seiko Instruments Inc. Also,
The water absorption rate is 2 mm in thickness and 50 mm in diameter, and a disk-shaped test piece is made into a thermo-hygrostat (manufactured by Tabai, HUMIDITY CABINE
T, LHL-111) and the rate of increase in weight after being left for 96 hours under the conditions of 85 ° C. and 85% humidity.

[0025]

[Table 1]

From the results shown in Table 1, the self-cured cured product of the present invention has lower water absorption than the cured product of the conventional epoxy resin composition having almost the same glass transition temperature (heat resistance). Is recognized.

Claims (1)

[Claims] 1. A phenol novolac resin having a number average molecular weight of 450 to 1000 is reacted with an allyl halide,
A method for producing a partially glycidyl etherified phenol novolac resin, which comprises allylating 20 to 80% of the hydroxyl groups of the phenol novolac resin and then epoxidizing the allyl group with peracid.