JP2631843B2 - Manufacturing method of glass cloth prepreg - Google Patents

Description

The present invention relates to a method for producing a glass cloth prepreg impregnated with an epoxy resin. More specifically, the present invention relates to a method for producing a prepreg made of glass cloth using a mixed solvent for an epoxy resin which is less toxic to living organisms and has excellent storage stability.

<< Prior Art >> An epoxy resin-glass cloth copper-clad laminate is a substrate that is frequently used after a phenol resin-paper copper-clad laminate.

This epoxy resin-glass cloth copper-clad laminate has better properties such as electrical insulation, moisture resistance, and dimensional stability than the phenol resin-paper copper-clad laminate. It is used for power distribution boards such as electronic desk calculators.

Epoxy resin-glass cloth-based copper-clad laminates are made by immersing glass cloth in a varnish in which a curing agent, a reaction accelerator and a solvent are mixed in an epoxy resin to impregnate the varnish into the gaps between individual fibers of the glass cloth, The varnish adhered to the varnish is removed by squeezing and then dried to produce a prepreg. The prepreg is further cut into predetermined dimensions, overlapped, and laminated with copper foil.

One of the important characteristics is the storage stability of the prepreg manufactured through the series of steps as described above. In order to prevent a decrease in moldability due to long-term storage, among high-temperature curing type curing agents, those that hardly lower the fluidity of the prepreg and that are latent curing agents that rapidly cure during press molding are used.

Such latent curing agents include dicyandiamide,
Examples include diphenyldiaminomethane and diphenylaminosulfone.

Above all, dicyandiamide can cure an epoxy resin with a small amount of addition, and can produce a prepreg having a longer storage period than when other curing agents are used.

In order to prepare a prepreg having a uniform surface from a composition using dicyandiamide as a curing agent, dicyandiamide must be completely dissolved in the resin.

Therefore, a method of dissolving dicyandiamide using a solvent and mixing a resin with the solution is adopted.

Solvents that can be used at this time are limited, and include dimethylformamide, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, etc., all of which are high boiling solvents and require high drying temperatures after impregnation of the substrate. And Among them, ethylene glycol monomethyl ether has a boiling point of 125 ° C., is a solvent having a low boiling point as compared with the above-mentioned other solvents, and has relatively high solubility of dicyandiamide, so that it is often used in a prepreg production process.

As described above, when used as a curing agent, ethylene glycol monomethyl ether is used as a solvent during production of a varnish composition in consideration of the properties of dicyandiamide.

It is preferable that the epoxy resin is dissolved in ethylene glycol monomethyl ether in advance so that it can be completely mixed with the curing agent.

Therefore, in some cases, the market is traded as a composition in which an epoxy resin is dissolved in ethylene glycol monomethyl ether.

<< Problems to be solved by the invention >> However, at present, the epoxy resin solution composition using ethylene glycol monomethyl ether as a solvent, which is traded on the market, is highly toxic to living organisms and lacks storage stability. There was a problem.

First, animal experiments have shown that ethylene glycol monomethyl ether can damage living organisms at relatively low concentrations.

For example, testicular disorders, reduced fertility, fetal toxicity, maternal toxicity, reduced bone marrow and immune function, neurotoxicity, and the like have been pointed out.

In addition, epidemiological and clinical studies have revealed examples of disorders such as sperm loss, irregular menstruation, blood disorders, and neurotoxicity.

Solvent vapors generated during exposure during drying after impregnation of the substrate pose a great danger to the operator. In addition, epoxy resin solution compositions currently marketed undergo an increase in viscosity during prolonged storage. This is caused by the reaction of the primary OH group of ethylene glycol monomethyl ether with the epoxy resin, and was an important problem in the manufacturing process in the manufacturing industry.

In view of these circumstances, the present inventors have conducted intensive studies to find an epoxy resin solution composition that is safe for the human body and has excellent storage stability, and as a result, completed the present invention.

<< Means for Solving the Problems >> That is, the present invention relates to a method for producing a glass cloth prepreg by mixing and mixing an epoxy resin solution composition obtained by dissolving an epoxy resin in a solvent and a curing agent or a curing agent solution. And the solvent has the following formula (I) 95 to 100 parts by weight of a substance represented by the following formula (II) A method for producing a glass cloth prepreg, comprising using a mixed solvent obtained by mixing 5 to 0 parts by weight of a substance represented by the formula: It is.

<< Embodiment of the Invention >> Here, the substance represented by the above formula (I) is called 1-methoxy-2-propylene glycol, generally 1-methoxypropanol, and the substance represented by the above formula (II) is 2-methoxy-2-propanol. Methoxy-1-propylene glycol, generally 1
It is widely known as a solvent with low toxicity called -methoxy-2-propanol.

1-methoxy-propanol can be prepared by reacting the compounds of formula (III) and formula (I
It is obtained by the reaction of the substance represented by V), and 2-methoxypropanol is obtained as a by-product of the reaction.

CH ₃ OH (III) The mixture ratio of 1-methoxypropanol and 2-methoxy-propanol can be adjusted by the reaction temperature and the distillation after the reaction.

What is marketed widely as methoxypropanol in the general market is this mixture of 1-methoxypropanol and 2-methoxypropanol, which contains 1.6-2.5% of 2-methoxypropanol.

In the present invention, when a glass cloth prepreg is produced, when used as a solvent for an epoxy resin solution composition to be impregnated, 2-methoxypropanol is used in an amount of 0 to 0.
It is better to contain 5.0%.

That is, in the production of methoxypropanol, 2
-It is sufficient that the content of methoxypropanol is reduced to the separation and purification degree of 5.0%.

Here, in the present invention, when a glass cloth prepreg is used as a solvent for an epoxy resin solution composition to be impregnated and used, when the proportion of 2-methoxypropanol is more than 5.0%, the second methoxypropanol has The primary OH group reacts with the epoxy resin, and the viscosity of the epoxy resin composition is extremely increased, which makes it difficult to mix the epoxy resin composition with the curing agent solution composition.

Examples of the epoxy resin used include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, alicyclic epoxy resin, glycidyl ester type epoxy resin, and glycidyl. Amine type epoxy resin, hydantoin type epoxy resin, isocyanurate type epoxy resin, glycidyl etherified product of polycondensate of bisphenol A or bisphenol F and formaldehyde and their halides, hydrogenated products, etc. You can also.

Further, there is no limitation on the method and temperature for mixing these epoxy resins.

The characteristics required for epoxy resin for substrates are that they are solid at room temperature, have good affinity with the substrate, that they have stable curability, and that they do not contain impurities that reduce the electrical characteristics of the laminated board. Good varnish and prepreg preservability, good adhesion to copper foil, good electrical and mechanical properties, good workability of the laminate, and the like.

Bisphenol A, one of the representative epoxy resins
Among the mold epoxy resins, those having an epoxy equivalent of 190 to 1000 are used for producing a laminate.

Particularly, a copper-clad laminate is often a solid epoxy resin having an epoxy equivalent of about 450 to 550 at room temperature.

Bisphenol A type epoxy resin has good adhesiveness to copper foil and glass cloth, and has excellent heat resistance, flexibility, mechanical properties, and chemical resistance. Therefore, it is a typical resin used for a copper-clad laminate. An epoxy resin produced by reacting epichlorohydrin with a novolak-type phenol resin or cresol resin has two or more functional groups (epoxy groups) in one molecule. The crosslink density after curing increases. Therefore, the heat resistance, solvent resistance, chemical resistance, dimensional stability, etc. of the laminate are improved. However, on the other hand, there are disadvantages such as the peeling of the copper foil, the adhesiveness is lowered, and the resin becomes brittle. Therefore, a laminated board is not made only of the novolak type epoxy resin, and is used for improving heat resistance and dimensional stability by adding it to the bisphenol A type epoxy resin.

1 for 100 parts by weight of bisphenol A epoxy resin
By adding 0 parts by weight of the novolak type epoxy resin, the solvent resistance and heat resistance of the laminate are improved, but when 20 parts or more are added, the working time of the prepreg and the adhesive strength of the copper foil are reduced. . In addition, the punching workability, the shearing properties of the laminate, etc. are also reduced. Instead of using a novolak type epoxy resin, using a low molecular weight epoxy resin having an epoxy equivalent of about 180 to 200 of a bisphenol A type epoxy resin has also been adopted as a method of improving heat resistance by increasing the crosslink density of the cured resin. .

However, in general, by increasing the crosslink density of the epoxy resin, the heat resistance of the epoxy resin is improved, but the flexibility of the resin is lost, so the adhesive strength of the copper foil, particularly the peeling strength, tends to decrease. .

Commercial brominated epoxy resins have a bromine content of 18-48%
There are even things.

Those having a high bromine content have a large flame-retarding effect, but tend to reduce heat resistance, and also reduce the solubility when dissolved in an organic solvent to form a varnish. Therefore, it is necessary to use a mixture with a low brominated resin or a bisphenol A type epoxy resin. When higher heat resistance is required, the flame retardancy can be further improved by using a brominated epoxy resin and using a curing agent having a halogen in the molecule in combination therewith.

The use of an inorganic flame retardant such as antimony oxide is also effective in improving the flame retardancy. In any case, the flame retardancy of the epoxy resin is directly related to the halogen content in the combination of epoxy resin and curing agent.

It is necessary to control the halogen content in the resin-hardener ratio depending on the required degree of flame retardancy. An epoxy resin having a high bromination ratio generally has high crystallinity, and may be precipitated when dissolved in an organic solvent to form a varnish. Therefore, a uniform prepreg is obtained by blending a halogen-containing curing agent with one having a bromine content of 18 to 20%.

The mixing ratio of the mixed solvent of 1-methoxypropanol and 2-methoxypropanol to the epoxy resin is not particularly limited.

However, in order to produce a uniform and high quality prepreg,
It is desirable to control the concentration of the epoxy resin so that the viscosity of the epoxy resin solution composition becomes 150 to 250 centipoise at 25 ° C.

The correlation between the epoxy resin concentration and the viscosity differs depending on the resin. Examples are shown in FIG. 1 [Epoxy resin (Epicoat 1001) concentration (%) (Epibis type epoxy-Cyer Epoxy Co., Ltd.)] and FIG. (Araldite
8011) Concentration (%) (Brominated Epoxy-Ciba-Geigy Inc.)
It was shown to. Epibis epoxy resin (Epicoat 1001)
It is clear that the desired viscosity can be obtained by using an epoxy resin concentration of 50-55% and a brominated epoxy resin (Araldite 8011) by using an epoxy resin concentration of 55-65%.

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples.
The present invention is not limited by these. In the examples, “parts” are all parts by weight.

<Example-1> Bisphenol A type epoxy resin (Ciba-Geigy-GY60
71) Weigh 100 parts by weight into a three-necked flask and add
29 parts of a mixed solvent of 99.5 parts of methoxypropanol and 0.5 part of 2-methoxypropanol were added to the flask.

Next, the inner temperature of the flask was heated to 80 ° C. by a mantle heater, and the flask was kept as it was, and stirred and dissolved for 3 hours.

The three-necked flask was equipped with a condenser, a nitrogen inlet tube, and a thermometer.

The flow rate of nitrogen was extremely small, and the space in the separable flask was filled with nitrogen. The following stability test was performed using the obtained epoxy resin solution composition.

The epoxy resin solution composition is sealed in ampoules in an air atmosphere and a nitrogen atmosphere, and left in an oil bath at 80 ° C. for 3 weeks to test the stability by heating. Hue, epoxy equivalent, viscosity, and curability when mixed with a curing agent solution composition were taken as evaluation indices. The results are shown in Table 1.

Example 2 29 parts of a mixed solvent of 98.0 parts of 1-methoxy-propanol and 2.0 parts of 2-methoxypropanol and bisphenol A
100 parts by weight of a type epoxy resin (Ciba-Geigy-GY6071) was weighed in the same apparatus as in Example 1, and an epoxy resin solution composition was obtained in the same manner. The epoxy resin solution composition was evaluated by the same stability test as in Example-1. The results are shown in Table 1.

Example 3 29 parts of a mixed solvent of 95.0 parts of 1-methoxypropanol and 5.0 parts of 2-methoxypropanol and 100 parts by weight of a bisphenol A type epoxy resin (Ciba-Geigy-GY6071) were weighed into the same apparatus as in Example-1. An epoxy resin solution composition was obtained in the same manner as in Example 1. The epoxy resin solution composition was evaluated by the same stability test as in Example-1. The results are shown in Table 1.

<Comparative Example> 29 parts of ethylene glycol monomethyl ether and bisphenol A type epoxy resin (Ciba-Geigy-GY-6071) 10
0 parts by weight was weighed into the same apparatus as in Example 1, and an epoxy resin solution composition for glass cloth prepreg was obtained in the same manner. The epoxy resin solution composition was evaluated by the same stability test as in Example-1. The results are shown in Table 1.

<< Effects of the Invention >> According to Examples-1 to 3 and Comparative Example, the substance represented by the formula (I) or a mixture of the substance represented by the formula (I) and the substance represented by the formula (II) is stored safely for the production of glass cloth prepreg. It is shown to be a mixed solvent for epoxy resins with excellent stability.

[Brief description of the drawings]

FIG. 1 and FIG. 2 show the correlation between the epoxy resin concentration and the viscosity of the epoxy resin solution composition, respectively.

Claims (1)

(57) [Claims] An epoxy resin solution composition in which an epoxy resin is dissolved in a solvent and a curing agent or a curing agent solution are mixed and impregnated to produce a prepreg made of glass cloth. 95 to 100 parts by weight of a substance represented by the following formula (II) A method for producing a glass cloth prepreg, comprising using a mixed solvent obtained by mixing 5 to 0 parts by weight of a substance represented by the formula: