JP3171700B2 - Phenolic resin molding material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phenolic resin molding material having excellent moldability and curability. In particular, in an injection molding, a curing reaction hardly progresses in a cylinder of an injection molding machine, and the molding reaction takes place in a mold. The present invention provides a phenolic resin molding material which is extremely excellent in molding processability and cures very quickly.

[0002]

2. Description of the Related Art Phenolic resin molding materials are used in a wide range of applications such as automobile parts, electronic / electric parts, and mechanical parts because of their excellent heat resistance, electric performance, mechanical performance, and the like. However, the conventional phenolic 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, and the viscosity increases to 10 to 30 ° C.
It has the property of losing fluidity within minutes, and the thermal stability of the plasticized molten resin is extremely low. For this reason, when injection molding a conventional phenolic resin molding material, there is a problem that the thermal stability of the plasticized and melted molding material in the cylinder of the injection molding machine is extremely poor, and the range of appropriate molding conditions is extremely narrow. Conventionally, various methods for solving this problem, such as increasing the fluidity of the molding material, are known. However, when the thermal stability in the plasticized molten state is improved, 150-
When the curing reaction at 200 ° C. becomes slow, and conversely, when the curability in the mold is improved, the thermal stability becomes inferior, and the thermal stability in the plasticized molten state and the curability in the mold are reduced. It is difficult to obtain a phenolic resin molding material in which both are simultaneously improved.

[0003]

DISCLOSURE OF THE INVENTION The present invention relates to various phenolic resin molding materials having improved moldability and improved heat stability in a plasticized molten state and curability in a mold. The purpose of this study was to make phenolic resin, which is particularly excellent in thermal stability in the plasticized molten state in a cylinder and extremely excellent in curability in a mold in injection molding. Providing molding materials.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a phenolic resin molding material comprising (a) a phenolic resin, (b) hexamethylenetetramine, (c) a blocked isocyanate, and (d) a filler. Things. As the phenolic resin of the present invention, a normal novolak-type phenolic resin obtained by a reaction between phenols and formaldehyde is used. Examples of the phenols of the phenol resin include one or more of monovalent and polyvalent phenols such as phenol, cresol, xylenol, naphthol, Pt-butylphenol, bisphenol A, and resorcinol, and substituted products thereof. Examples can be given. Examples of the formaldehydes include formalin and paraformaldehyde. Further, as the phenol resin of the present invention, a resin suitably modified with an aromatic hydrocarbon resin, dimethoxyparaxylene, dicyclopentadiene or the like can be used.

As the hexamethylenetetramine of the present invention, a powdery one used as a usual curing agent for a phenol resin is used, and 7 to 30 parts by weight, preferably 12 to 20 parts by weight, per 100 parts by weight of the phenol resin is used. Used in combination. The blocked isocyanate of the present invention is a polyisocyanate blocked with a blocking agent such as alcohols, phenols, oximes, amines, amides, imides, lactams, β-dicarbonylic compounds, and 100 ° C. or lower. Is inactive at a temperature of 130 ° C., but dissociates into isocyanate and blocking agent at a high temperature of 130 ° C. or higher. Examples of the blocking agent include phenol, cresol, 3,5-xylenol,
Isononylphenol, methyl ethyl ketoxime, ε
-Caprolactam, diethyl malonate, ethyl acetoacetate, benzotriazole and the like.
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, hexamethylene diisocyanate, and the like. And one or more of these can be used. A preferred isocyanate is Polymeric M
DI and a 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 amount is too small, the effect of accelerating the curing is lost, and if it is too large, the mechanical and thermal properties of the cured product are reduced.

As the filler of the present invention, organic fillers such as wood powder, pulp powder, pulverized various fabrics, pulverized thermosetting resin laminates and molded articles, 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 in an amount of 50 to 150 parts by weight based on 100 parts by weight of the phenol resin. In the present invention, additives such as a flame retardant, a colorant, and a release agent can be appropriately blended and used as necessary. In the present invention, if necessary, a phenol compound such as a resol-type phenol resin, resorcin, bisphenol F, and biphenol can be appropriately blended and used within 20 parts by weight based on 100 parts by weight of the phenol resin. The phenolic resin molding material of the present invention is prepared by blending a phenolic resin, hexamethylenetetramine, blocked isocyanate, a filler and various additives, melt-kneading with a roll mill, a twin-screw kneader or the like, cooling, and then pulverizing. Can be manufactured.

[0007]

The phenolic resin molding material of the present invention has a 90-1
It has remarkably excellent thermal stability in a plasticized molten state at 25 ° C, and has extremely excellent curability at 150 to 200 ° C in a mold. Although the reason for this is not fully understood, the blocked isocyanate is inactive when the molding material is in the plasticized molten state, but dissociates at the temperature in the mold, and the dissociated isocyanate becomes hexamethylenetetramine and phenol resin. It is presumed that it reacts with a reaction intermediate with hexamethylenetetramine to form a cured structure.
When the blocking agent is 3,5-chylenol, the dissociated 3,5-chylenol promotes the curing reaction between the phenolic resin and hexamethylenetetramine, so that the curability is further improved. Can be

[0008]

The present invention will be described below with reference to examples. Here, "parts" represents parts by weight. [Example 1] 44 parts of a novolak resin (number average molecular weight 800) obtained by a reaction between phenol and formaldehyde,
7 parts of hexamethylenetetramine powder, 20 parts of polymeric MDI blocked with 3,5-xylenol,
30 parts of wood powder, 10 parts of calcium carbonate, and 2 parts of a release agent were mixed, melt-kneaded in a two-roll mill, cooled and pulverized to obtain a phenolic resin molding material. [Example 2] A phenolic resin molding material was obtained in the same manner as in Example 1 except that 20 parts of tolylene diisocyanate blocked with ε-caprolactam 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 methyl ethyl ketoxime was used instead of the blocked isocyanate of Example 1. [Comparative Example 1] 44 parts of a novolak resin (number average molecular weight 800) obtained by the reaction of phenol and formaldehyde, 7 parts of hexamethylenetetramine powder, 4 parts of calcium hydroxide
Parts, 32 parts of wood flour, 11 parts of calcium carbonate, and 2 parts of a release agent, were melt-kneaded in a two-roll mill, cooled and pulverized to obtain a phenolic 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 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., and the rotor is rotated to plasticize and melt the molding material, and the torque of the rotor rotation is measured. As the viscosity of the resin increases as the curing proceeds, the torque increases, and finally the fluidity is lost and the torque increases sharply. The time from the start of the measurement to the sudden rise of the torque was measured, and this time was regarded as the thermal stability. The longer the time, the better the thermal stability. The curability shown in Table 1 indicates the curing speed of the molding material in the mold. The transfer molding machine having a cavity having a diameter of 50 mm and a thickness of 3 mm and having a mold maintained at 175 ° C. 30 g of a tablet-shaped molding material preheated to 100 to 105 ° C. by a preheater is charged, and 40
The molded product was taken out after 10 seconds, and the molded product hardness after 10 seconds was measured using a Barcol hardness meter No. 1. 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 have extremely excellent heat stability and curability as compared with the conventional phenolic resin molding material of Comparative Example 1. You can see that it is. 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 molten state was allowed to stand in the cylinder as it was, all the materials of Examples 1 to 3 were left for 90 minutes, and then 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 the operation.

[0013]

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

Claims (1)

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