JPH0667999B2 - Resol type phenol resin manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a resol-type phenol resin.

[Conventional technology]

Phenolic resins are roughly classified into novolac type and resol type depending on whether the molecular structure is linear type or three-dimensional type, and they have industrially different uses due to the difference in their characteristics. For example, the latter resol-type phenolic resin has the property of being insoluble and infusible when it is heat-cured as it is or when it is cured at room temperature in the presence of an acid catalyst. Widely used as a material.

Which type of phenolic resin is used is determined by its production method, and when an excess amount of phenol is reacted with an aldehyde in the presence of an acid catalyst, a novolak type is obtained. On the other hand, when excess aldehydes are reacted with phenols in the presence of an alkali catalyst such as ammonia and the resulting initial condensate is further dehydrated and condensed, a crosslinking reaction proceeds and solid resol-type phenol resin (resole Alternatively, a resol resin) can be obtained.

[Problems to be Solved by the Invention]

By the way, conventionally, the above solid resol resin has a problem that it lacks thermal stability when the resin is taken out at the time of resin production and the resin gels. Further, the molding material using the solid resol resin has a drawback that it lacks in cylinder stability and storage stability during injection molding.

In view of the above circumstances, it is an object of the present invention to provide a method for producing a resol-type phenol resin having a high softening point, excellent thermal stability, and being less likely to gel during resin removal during production.

[Means for Solving the Problems]

In order to solve the above problems, the present invention is produced by addition-condensing excess aldehydes to phenols in the presence of an alkali catalyst, and then dehydrating to obtain a resole-type phenol resin, which is produced during the dehydration step. Initial condensate 100
With respect to parts by weight (hereinafter referred to as “parts”), bisphenol A epoxy resin, bisphenol F epoxy resin,
3 to 50 parts by weight of at least one epoxy resin selected from novolac type epoxy resin, brominated epoxy resin, alicyclic epoxy resin and heterocyclic epoxy resin is added.

[Action]

If the epoxy resin was added from the beginning, the addition condensation reaction between the phenols and the aldehydes would be hindered, and at the stage of dehydration condensation, even if the epoxy resin was added, it would be mixed well with the resole resin. There is a problem that there is no compatibility (poor compatibility). Therefore, in this invention, the epoxy resin is added during the dehydration step.

The amount of the epoxy resin added is set to 3 to 50 parts based on 100 parts of the phenol-aldehyde methylol type initial condensate. If the addition amount is less than 3 parts, the effect of adding the epoxy resin in the present invention cannot be obtained, and if it exceeds 50 parts, the compatibility is lowered and the strength is lowered.

Since the epoxy resin is added to the obtained resole resin within the above range, characteristics such as electric insulation and heat resistance peculiar to the epoxy resin are imparted, and thermal stability and electric characteristics are improved.

〔Example〕

The phenols and aldehydes that are raw materials for the resole resin are not particularly limited, and any compound can be used in any combination. For example, phenols include phenol, cresol, xylenol, chlorophenol, p-alkylphenol, p-phenylphenol, bisphenol A, resorcinol and the like, and aldehydes include general formaldehyde, paraformaldehyde, acetaldehyde, furfural There are things.

Examples of the alkali catalyst used in the reaction include tertiary amines such as triethylamine and trimethylamine, primary amines such as methylamine and ethylamine, secondary amines such as dimethylamine, pyridine, and alkali metal hydroxides such as sodium hydroxide and potassium hydroxide. Examples thereof include, but are not limited to, alkaline earth metal hydroxides such as calcium hydroxide and magnesium hydroxide, and ammonia. The above catalysts may be used alone or in combination of two or more.

The addition condensation reaction of the above-mentioned phenols with an excess amount of aldehydes with respect to the above-mentioned phenols is carried out according to a usual method, and the addition amount thereof, reaction conditions and the like including the above-mentioned catalyst are not particularly limited. From the same reaction, a methylol type initial condensate obtained by adding 1 to several moles of aldehyde to phenols can be obtained.

After that, when the above initial condensate is dehydrated and condensed, cross-linking due to a methylene bond or a dimethylene ether bond occurs, and a solid resol resin is produced. It is a feature of this invention that an epoxy resin is added during this dehydration step.

The epoxy resin to be added is a bisphenol A epoxy resin, a bisphenol F epoxy resin, a novolac type epoxy resin, a brominated epoxy resin, an alicyclic epoxy resin and a heterocyclic epoxy resin. These may be used alone or in combination of two or more. The epoxy equivalent and softening point of those resins are not particularly limited, but for example, epoxy equivalent of 700 to 2000 in the case of bisphenol A epoxy resin and epoxy equivalent of 200 to 1000 in the case of cresol novolac type epoxy resin. It is more preferable that the softening point thereof is about 90 to 130 ° C.

The dehydration step is performed according to a usual production method except that the epoxy resin is added. Although there is no particular limitation such as depressurization conditions, the obtained initial condensate is thermally unstable.
It is preferable to set a pressure at which dehydration is performed at a temperature of not higher than 0 ° C, for example, at about 40 to 50 ° C.

The obtained solid resol resin is, for example, glass fiber,
These ingredients are combined with fillers such as wood powder, asbestos, mica and calcium carbonate, and general molding aids such as plasticizers, mold release agents, diluents, lubricants, colorants, etc., if necessary. By mixing with a blender or the like and kneading with a kneader or roll, it can be used as a molding material. After kneading, it may be cooled and solidified if necessary, and may be pulverized into particles or the like.

It should be noted that the resol-type phenolic resin obtained according to the production method of the present invention has a wide range of applications as a coating material, a dip material, a casting material, a paint, an adhesive, etc., in addition to various molding materials. There is no end.

Next, more detailed examples of the present invention will be described together with comparative examples.

Examples 1 to 4 Formalin (40%) in an amount corresponding to 1.6 mol of formaldehyde was added to 1 mol of phenol, and the mixture was added with aqueous ammonia.
After adjusting the pH to 8-9, the reaction was carried out at 105 ° C for 30 minutes.

Then, the amount of epoxy resin shown in Table 1 was added to the obtained initial condensate, and dehydration condensation was performed at 40 to 50 ° C. under reduced pressure to obtain a solid resol resin. The epoxy resin is bisphenol A with a softening point of 94 ° C and an epoxy equivalent of 900.
-Based epoxy resin (I) or bisphenol A epoxy resin (II) with a softening point of 120 ° C and an epoxy equivalent of 1800
Was used.

Comparative Example A solid resol resin was obtained in the same manner as in the above example except that the epoxy resin was not added during the dehydration step.

To 50 parts of the resol type phenolic resin obtained in the above Examples and Comparative Examples. Wood powder as filler (100-200 mesh)
40 parts and 5 parts of calcium carbonate, 2 parts of zinc stearate as a release agent, and 1 to 2 parts of a coloring agent were added and mixed in a mixer and then kneaded to obtain a molding material. Further, the same molding material is molded according to a conventional method (pressure 100 to 200 kg /
cm ² , temperature 150 to 160 ° C., time 1 to 3 minutes) to obtain a cured product.

The softening point of the solid resol resin, the pot life at 110 ° C., the insulation resistance of the molding material after curing, and the residence time in the cylinder during injection molding were measured, and the results are also shown in Table 1.

As shown in Table 1, the resole resin of the example prepared by adding the epoxy resin during the dehydration step has a wider thermal stability than that of the comparative example, has a high softening point, and has a long pot life. It has become. Further, it has been found that the molding material using this resol resin has excellent cylinder stability and gives a cured product having high insulation resistance.

〔The invention's effect〕

According to the method for producing a resol-type phenol resin according to the present invention, a solid resol resin having high thermal stability and excellent electric characteristics can be obtained. Therefore, the resin can be easily taken out without causing gelation or the like at the time of taking out the resin during manufacturing. Furthermore, when the same resole resin is used as the molding material, the cylinder stability during injection molding is improved and the storage stability is also excellent.

Claims (1)

[Claims] 1. When an excess aldehyde is added and condensed to phenols in the presence of an alkali catalyst and then dehydrated to obtain a resol-type phenol resin, 100 parts by weight of an initial condensate formed during the dehydration step is used. In contrast, bisphenol A epoxy resin, bisphenol F epoxy resin, novolac type epoxy resin, brominated epoxy resin,
A method for producing a resol-type phenol resin, which comprises adding 3 to 50 parts by weight of at least one epoxy resin selected from an alicyclic epoxy resin and a heterocyclic epoxy resin.