JPH06145291A - Phenolic resin molding material - Google Patents

Abstract

PURPOSE:To provide the subject molding material highly excellent in the thermal stability in the plasticized molten state in a cylinder in its injection molding and in the curability in a mold, comprising a phenolic resin, hexamethylenetetramine, a blocked isocyanate and filler. CONSTITUTION:The objective molding material comprising (A) 100 pts.wt. of a phenolic resin, (B) pref. 12-20 pts.wt. of hexamethylenetetramine, (C) pref. 5-20 pts.wt. of a blocked isocyanate (pref. a polymeric 4,4'-diphenylmethane diisocyanate blocked with 3,5-xylenol or epsilon-caprolactam) and (D) pref. 50-150 pts.wt. of a filler. This material can pref. be obtained by a conventional method, for example, by blending the components A to D followed by melt kneading with e.g. a roll mill, twin-screw kneader followed by cooling and grinding. The component A is pref. a conventional novolak-type phenolic resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phenol resin molding material excellent in molding processability and curability, and particularly in injection molding, the curing reaction hardly progresses in the cylinder of the injection molding machine, and The present invention provides a phenol resin molding material having extremely excellent molding processability that cures extremely quickly.

[0002]

2. Description of the Related Art Phenolic resin molding materials are excellent in heat resistance, electrical performance, mechanical performance and the like, and are therefore used in a wide range of applications such as automobile parts, electronic / electrical parts and mechanical parts. However, the conventional phenol resin molding material is 9
In the molten state plasticized to 0 to 125 ° C., the viscosity increases due to the progress of the curing reaction of the resin in the material.
It has the property of losing fluidity in minutes, and the thermal stability of the plasticized molten resin is extremely low. Therefore, when a conventional phenol resin molding material is injection-molded, there is a problem that the plasticization-melted molding material in the cylinder of the injection molding machine is significantly inferior in thermal stability and an appropriate molding condition range is extremely narrow. Conventionally, various methods such as increasing the fluidity of the molding material have been known as a method for solving this problem. However, if the thermal stability in the plasticized and molten state is improved, it is 150-
The curing reaction at 200 ° C. slows down, and conversely, when the curability in the mold is improved, the thermal stability becomes poor, and the thermal stability in the plasticized and molten state and the curability in the mold are reduced. It is difficult to obtain a phenol resin molding material in which both of the above are simultaneously improved.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides various kinds of phenol resin molding materials having excellent molding processability in which both thermal stability in a plasticized and molten state and curability in a mold are improved. It was made as a result of the study, and the purpose is especially a phenolic resin which is extremely excellent in thermal stability in a plasticized and molten state in a cylinder in injection molding and is extremely curable in a mold. To provide the molding material.

[0004]

The present invention relates to a phenol resin molding material containing (a) phenol resin, (b) hexamethylenetetramine, (c) blocked isocyanate, and (d) filler. It is a thing. As the phenol resin of the present invention, a normal novolac type phenol resin obtained by reacting phenols with formaldehyde is used. As the phenols of the phenol resin, one or more kinds of monovalent and polyvalent phenols such as phenol, cresol, xylenol, naphthol, Pt-butylphenol, bisphenol A, resorcin and their substitution products are used. It can be illustrated. Examples of the formaldehydes include formalin and paraformaldehyde. Further, as the phenol resin of the present invention, those modified with aromatic hydrocarbon resin, dimethoxyparaxylene, dicyclopentadiene and the like can be used.

As the hexamethylenetetramine of the present invention, a powdery one used as a curing agent for ordinary phenol resins is used, and 7 to 30 parts by weight, preferably 12 to 20 parts by weight, relative to 100 parts by weight of the phenol resin is used. Used by blending. The blocked isocyanate of the present invention is a polyisocyanate blocked with a blocking agent such as alcohols, phenols, oximes, amines, amides, imides, lactams and β-dicarbonic compounds, and is 100 ° C or lower. Although it is inactive at the temperature of 1, a compound that dissociates into an isocyanate and a blocking agent at a high temperature of 130 ° C. or higher is used. As the blocking agent, phenol, cresol, 3,5-xylenol,
Isononylphenol, methyl ethyl ketoxime, ε
Examples thereof include caprolactam, diethyl malonate, ethyl acetoacetate, and benzotriazole.
Examples of the polyisocyanate include tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate (MDI), polymeric MDI, xylene diisocyanate, naphthalene diisocyanate, isophorone diisocyanate, hydrogenated xylene diisocyanate, hydrogenated MDI, and hexamethylene diisocyanate. And one or more of these can be used. Preferred isocyanate is Polymeric M
DI and the preferred blocking agent is 3,5-xylenol or ε-caprolactam. In the present invention, the blocked isocyanate is used in an amount of 3 to 40 parts by weight, preferably 5 to 20 parts by weight, based on 100 parts by weight of the phenol resin. If the blending amount is small, the curing acceleration effect is lost, and if the blending amount is large, the mechanical properties and thermal properties of the cured product deteriorate.

As the filler of the present invention, organic materials such as wood powder, pulp powder, pulverized products of various fabrics, pulverized products of thermosetting resin laminates and molded products, silica, alumina, aluminum hydroxide, glass, Inorganic powders such as talc, clay, mica, calcium carbonate, and carbon, and inorganic fibers such as glass fiber, carbon fiber, and asbestos are used, and one or more of these can be used. These fillers are used by mixing 50 to 150 parts by weight with respect to 100 parts by weight of the phenol resin. In the present invention, additives such as a flame retardant, a coloring agent, and a release agent can be appropriately mixed and used as necessary. Further, in the present invention, if necessary, a phenol compound such as a resole type phenol resin, resorcin, bisphenol F or biphenol can be appropriately mixed and used within 20 parts by weight with respect to 100 parts by weight of the phenol resin. The phenol resin molding material of the present invention is prepared by blending a phenol resin, hexamethylenetetramine, blocked isocyanate, a filler and various additives, melt-kneading the mixture with a roll mill, a twin-screw kneader, etc., and after cooling, it is a usual method such as grinding Can be manufactured in.

[0007]

The function of the phenol resin molding material of the present invention is 90 to 1
It is remarkably excellent in thermal stability in a plasticized and melted state at 25 ° C., and is extremely excellent in curability in a mold at 150 to 200 ° C. The reason for this is not clear enough, but the blocked isocyanate is inactive when the molding material is in the plasticized and molten state, but dissociates at the temperature in the mold, and the dissociated isocyanate becomes hexamethylenetetramine and phenol resin. It is believed that this is due to reaction with a reaction intermediate with hexamethylenetetramine to form a cured structure.
When the blocking agent is 3,5-kylenol, the dissociated 3,5-kylenol accelerates the curing reaction between the phenol resin and hexamethylenetetramine, which is considered to further improve the curability. To be

[0008]

EXAMPLES The present invention will be described below with reference to examples. Here, "parts" represent parts by weight. Example 1 44 parts of novolak resin (number average molecular weight 800) obtained by the reaction of phenol and formaldehyde,
Hexamethylenetetramine powder 7 parts, 3,5-xylenol blocked polymeric MDI 20 parts,
30 parts of wood powder, 10 parts of calcium carbonate and 2 parts of a release agent were mixed, melt-kneaded with a two-roll mill, cooled and ground to obtain a phenol resin molding material. Example 2 A phenol resin molding material was obtained in the same manner as in Example 1 except that 20 parts of ε-caprolactam-blocked tolylene diisocyanate was used instead of the blocked isocyanate of Example 1.

[Example 3] A phenol resin molding material was obtained in the same manner as in Example 1 except that 20 parts of MDI blocked with methylethylketoxime was used instead of the blocked isocyanate of Example 1. [Comparative Example 1] 44 parts of novolac resin (number average molecular weight 800) obtained by the reaction of phenol and formaldehyde, 7 parts of hexamethylenetetramine powder, and 4 parts of calcium hydroxide.
Parts, 32 parts of wood powder, 11 parts of calcium carbonate, and 2 parts of a release agent were mixed, melt-kneaded with a two-roll mill, cooled and pulverized to obtain a phenol resin molding material.

Table 1 shows the material properties of the phenolic resins obtained in Examples 1 to 3 and Comparative Example 1.

[Table 1]

The thermal stability shown in Table 1 represents the thermal stability of the molding material in the plasticized and molten state, and was measured by the following method. 28 g of a powdery molding material is charged into a Labo Plastomill (manufactured by Toyo Seiki Co., Ltd.) kept at 100 ° C., the rotor is rotated to plasticize and melt the molding material, and the torque of rotor rotation is measured. The torque increases as the viscosity increases with the progress of curing of the resin, and finally the fluidity is lost and the torque rapidly increases. The time from the start of measurement to the sudden rise in torque was measured, and this time was defined as thermal stability. The longer the time, the better the thermal stability. The curability in Table 1 represents the curing speed of the molding material in the mold, and a transfer molding machine having a cavity with a diameter of 50 mm and a thickness of 3 mm and having a mold kept at 175 ° C. was used for high frequency. 40 g of tablet-like molding material preheated to 100-105 ° C with a preheater
Molded for 2 seconds, taken out of the molded product, and the hardness of the molded product after 10 seconds was measured by a Barcol hardness tester No. It was measured at 935. The higher the hardness, the faster the curing speed and the better the curability.

From Table 1, the phenolic resin molding materials of the present invention shown in Examples 1 to 3 are extremely excellent in thermal stability and curability as compared with the conventional phenolic resin molding material of Comparative Example 1. You can see that In addition, Examples 1 to 3
And injection molding the phenolic resin molding material of Comparative Example 1,
When the molding machine was stopped on the way and the molding material in the plasticized and molten state was allowed to stand in the cylinder as it was, after all the materials of Examples 1 to 3 were left for 90 minutes, when the molding machine was restarted, However, when the material of Comparative Example 1 was left for 30 minutes, it hardened in the cylinder and it was difficult to restart.

[0013]

As can be seen from the above examples, the phenol resin molding material of the present invention has extremely excellent thermal stability in the plasticized and molten state and curability at high temperature. For this reason,
Particularly in injection molding, the progress of the curing reaction of the plasticized molten resin in the cylinder of the injection molding machine is significantly suppressed, and it rapidly cures in the mold, so it can be applied to a wide range of molding conditions and has excellent molding processability. ing. Further, the phenol resin molding material of the present invention is extremely suitable for sprue / runnerless molding because it has extremely excellent thermal stability in a plasticized and molten state.

Claims (1)

[Claims] 1. A phenolic resin, (b) hexamethylenetetramine, (c) blocked isocyanate,
(D) A phenol resin molding material containing a filler.