JPH0725989B2 - Phenol resin molding material - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention has an extremely high stability at a melting temperature of 50 to 170 ° C., the stabilization time of the melt viscosity is extremely long, and the condensation reaction proceeds rapidly at the curing temperature to achieve an ultra-high speed. The present invention relates to a fast-curing novolac-type phenol resin molding material that can be molded.

[Conventional technology]

More than 80% of phenol resin molding materials are molded by the injection molding method. Due to its good moldability, it has excellent thermal, physical, electrical and chemical properties, and it is highly stable and economically obtainable, so in a wide range of application fields such as electricity, automobiles, machinery, communications and daily necessities. Many are used.

In order to further improve the molding efficiency, it combines the excellent quality up to now, it helps to further shorten the curing time and molding cycle, and it is possible to increase the molding size such as increasing the number of molds and improve the dimension accuracy. Phenolic resin molding materials having excellent molding stability are strongly desired.

Conventionally, phenol resin molding materials include novolac type resin, hexamethylenetetramine and filler, reinforcing agent, release agent,
It is well known that it can be easily obtained by mixing liquid and powder raw materials of a curing aid, a plasticizer, and a colorant, heating and kneading them, and further forming a powder or granule into a molding material. .

The phenol resin molding material thus obtained is used for compression molding, transfer molding and injection molding as a thermosetting resin molding method. In any of the molding methods, the molding material is heated to a temperature higher than the softening point of the novolac type resin of the molding material to be plasticized, and pressure-transferred to a high temperature mold cavity by a pressure device of various molding machines. It is generally practiced to obtain a target molded article after the resin is cured after a predetermined time.

Conventional phenol resin molding materials use high ortho novolac, which has a high gelation rate with hexamethylenetetramine, and a high amount of hexamethylenetetramine and a high amount of catalyst, for the purpose of imparting fast curing properties that exhibit high quality in a short curing time. Compounding and molding at high mold temperatures are widely practiced. While such a molding material and method of use have a high reaction rate of the resin, they have the drawback that the gelation time is short even at the plasticizing temperature, so that it is difficult to mold a large molded product having a long flow distance. Even in a molded product having a short flow distance, the fluidity of the molten material is greatly affected by a change in molding conditions, and there is a problem that continuous molding for a long time is unstable.

Therefore, in the prior art, in order to achieve both curability and stable molding processability, a combination of a high ortho novolac resin and a low ortho bond ratio novolac resin or a low molecular weight novolac resin is used to suppress the gelation rate at the plasticizing temperature. As a result of improving the molding processability, there is a limit in shortening the curing time and molding cycle.

[Object of the Invention]

DISCLOSURE OF THE INVENTION The present invention has been made with the aim of achieving both flow stability (called heat stability) at a plasticizing temperature and rapid curability at a curing temperature, which were not possible with conventional phenolic resin molding materials. Hexamethylenetetramine Was surface-treated, and by using this in a usual phenol resin molding material manufacturing method, it was found that the thermal stability can be significantly improved without impairing the rapid curing property, and further research is conducted based on this finding. It has been completed.

It is an object of the present invention to provide a super-velocity curable phenol resin molding material which is extremely excellent in molding processability and has a short curing time and molding cycle.

[Structure of Invention]

The present invention is characterized in that hexamethylenetetramine coated with a surface treatment agent having a melting point of 80 ° C. to 200 ° C. is blended in an amount of 2 to 25 parts by weight as a hexamethylenetetramine content with respect to 100 parts by weight of a novolac type phenol resin. And a phenol resin molding material.

The phenolic resin used in the present invention is a novolak type resin prepared by mixing phenols such as phenol and cresol with formalin or paraformaldehyde in an F / P = 0.7 to 1.0 molar ratio and proceeding the condensation reaction under an acidic catalyst. Is used.

The surface treatment agent for coating hexamethylenetetramine used in the present invention is a C _{23 to} C ₄₅ linear saturated fatty acid, a C _{28 to} C ₃₂ saturated alcohol, a C _{6 to} C ₂₂ fatty acid amide and N, N ′.
Methylenebisamide, Cd salt of C ₁₀ or more saturated fatty acid, B
Metal salts such as a salt, Zn salt and Ca salt, C ₂₆ or higher fatty acid ester and polyolefin such as low molecular weight polyethylene having a molecular weight of 1000 to 5000, polyethylene glycol alkyl ether, nonionic activator such as fatty acid monoglyceride, alkyl sulfonic acid Anion activators such as salts and higher fatty acid esters, and cationic activators such as alkylpyridinium halides alone or in combination have a melting point or softening point of 80 to 20.
It is at 0 ° C.

At the softening point of the phenolic resin used, the hexamethylenetetramine particles are coated without melting any surface treatment agent, and as a result, the reaction with the novolak type resin can be suppressed, resulting in plasticization of the molding material. Stability of melt viscosity at temperature is obtained.

Also, when heated above the melting point or softening point of each surface treatment agent, the surface treatment agent coating migrates into the resin, does not interfere with the reaction between hexamethylenetetramine and the novolak resin, and reacts with the novolak resin. It can maximize the fast-curing property according to the property.

The surface treatment agent preferably coats the entire hexamethylenetetramine particles, but partial coating is also effective. As for the coating thickness, if the coating is thick, it will adversely affect the fast curing property,
If the coating is thin, hexamethylenetetramine participates in the reaction with the novolak resin, and thus tends to impair the stability during melting, and the particle size of hexamethylenetetramine is preferably 1/20 to 1 times.

The surface treatment of hexamethylenetetramine includes a method of melting and mixing a surface treatment agent having a melting point or a softening point higher than hexaethylene tetramine, a method of spraying a surface treatment agent having a melting point or a softening point higher than hexamethylenetetramine, and the like.
For example, it can be carried out by stirring and mixing with hexamethylenetetramine at a temperature exceeding the melting point or softening point of the surface treatment agent in a mixer, kneader, or extruder equipped with a heating device.

Further, a method of dissolving a surface treatment agent in a solvent and then mixing with hexamethylenetetramine, and then drying and volatilizing the solvent, a method of spraying a solution of the surface treatment agent dissolved in the solvent onto hexamethylenetetramine, and then drying and volatilizing the solvent. Is also effective. A method of physically coating is also effective, for example, stirring and mixing hexamethylenetetramine and a surface treatment agent, even in a rotating ball mill, because the surface treatment agent adheres to hexamethylenetetramine and agglomerates due to the frictional action with the mill. A rotating ball mill can be used.

Since the particle size of hexamethylenetetramine significantly affects the reactivity with the novolac type resin, it is preferable to adjust it to a fine powder having a particle size of 100 μm or less and perform the surface treatment.

Fillers that can be used in the phenol resin molding material of the present invention are wood powder, coconut husk powder, fir shell powder, corn powder, plywood powder, resin molded product powder, organic base materials such as pulp powder, calcium carbonate, clay, talc, Inorganic base materials such as aluminum hydroxide, magnesium hydroxide, magnesium carbonate, mica and asbestos diatomaceous earth can be used.

When higher mechanical strength is required, inorganic or organic fibers such as glass fiber, rock wool, kaolin wool or knitted cloth, pulp can be used.

Hexamethylenetetramine coated with the surface treating agent according to the present invention is mixed with a novolac resin and a filler, a reinforcing agent, a release agent, a curing aid, a plasticizer and a colorant, and the compounded composition is subjected to usual phenol resin molding. As in the material manufacturing method, a molding material can be obtained by heating and melting with a roll, a kneader, or the like.

Further, such treated hexamethylenetetramine can be added in the resin production process because it does not participate in the reaction with the novolak resin or is less likely to participate in the reaction at a temperature below the melting point of the surface treatment agent, and as a result, hexamethylenetetramine is extremely uniform. To help obtain a resin with uniform reactivity. By using such a resin as a molding material, it is possible to consistently obtain high-quality molded products with uniform cross-linking density and high quality, and high reliability of parts that require severe durability in automobiles and heavy electric applications. It is useful for improvement.

〔The invention's effect〕

The phenolic resin molding material of the present invention has the characteristic that the melt viscosity is extremely stable at the plasticizing temperature immediately before the material is injected into the mold, and after the material is filled into the mold, the material is transferred by heat from the mold. As the temperature rises, the curing reaction proceeds rapidly, and high-speed molding can be maximized without impairing the quality with a very short curing time, which was not possible with conventional phenol resin molding materials.

Especially in the injection molding of phenolic resin, the thermal stability of the molten material in the cylinder is dramatically improved, and as a result, cushion molding similar to thermoplastic resin injection molding, which was not possible with the conventional technology, becomes possible. It helps to stabilize the excellent and high quality by improving the packing density of the material in the mold. Also, it was difficult to mold with conventional technology, 200
Even in the molding temperature range of up to 250 ° C, stable continuous molding can be performed for a long time using a normal thermosetting resin injection molding machine, and the molding cycle can be increased by dramatically shortening the curing time. This is extremely useful because the efficiency of can be significantly increased.

[Examples and Comparative Examples]

A molding material composed of the blended composition shown in Table 1 was obtained by a usual method for producing a phenol resin molding material using a heating roll kneading device.

As shown in Table 2, in comparison with Comparative example-1 in which ordinary hexamethylenetetramine was used, in Example-1, the thermal stability in the cylinder was remarkably lengthened, and moreover, the mold temperature was increased. It was confirmed that the curing time could be shortened.

As shown in Comparative Example-2, when a novolak resin having a high O—P bond ratio (ortho / para bond ratio) and fast curing was used and ordinary hexamelenetetramine was used, the thermal stability in the cylinder was extremely poor, Cannot be molded.

It was confirmed that by using the surface-treated hexamethylenetetramine of Example 2 of the present invention, the thermal stability was improved and the curing time in the mold was very short. The effect of the present invention is remarkably exhibited when a novolac resin which cures quickly is used.

In Example 3, the effect of the present invention was confirmed by using polyethylene having a melting point of 107 ° C. as the surface treatment agent.

In Example 4, the effect of the present invention was confirmed by using caproic acid amide having a melting point of 101 ° C. as a surface treatment agent.

In Example 5, the effect of the present invention was confirmed by using surface-treated hexamethylenetetramine and untreated hexamethylenetetramine in combination.

Claims (1)

[Claims] 1. Hexamethylenetetramine coated with a surface-treating agent having a melting point or softening point of 80 to 200 ° C. is added to 100 parts by weight of a novolac type phenol resin in an amount of 2 to 25 parts by weight as a hexamethylenetetramine content. A phenolic resin molding material characterized in that