JPH0657098A - Phenol resin molding material for low-pressure molding - Google Patents

Abstract

PURPOSE:To provide, through a specific process, the phenol resin molding material excellent in packability in a mold and curability in its low-pressure molding, by using a resin component composed of a crystalline phenol compound and phenol resin, a specific curing agent, inorganic fine powder, etc. CONSTITUTION:(A) A two or more-nuclear crystalline phenol compound (e.g. bisphenol A), (B) a phenol resin, and (C) hexamethylenetetramine as curing agent, are put to melt-blending followed by incorporating the resultant composition with (D) inorganic fine powder 100nm or smaller in mean particle diameter, thus obtaining the objective molding material. It is preferable that the weight ratio A/B be (80:20) to (30:70). Specifically, this molding material can be obtained, for example, by the following process: novolak-type phenol resin, bisphenol F and hexamethylenetetramine are put to melt blending at 50 deg.C for 30min using a roll mill, and the ground product of the resultant composition is then mixed with calcium hydroxide and/or woodmeal, etc., followed by kneading with a twin-roll mill and then grinding.

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 low-pressure moldability and curability.

[0002]

2. Description of the Related Art Phenolic resin molding materials are excellent in heat resistance, electrical performance, mechanical performance, etc.
It is used in a wide range of applications such as electronic, electrical parts, and mechanical parts. However, the phenolic resin molding material
At the time of molding processing, it is injected into a high temperature mold to accelerate the curing reaction and solidify, so it takes longer to mold and solidify (curing) than a general thermoplastic resin molding material that is shaped by cooling. It has the drawback of a long molding cycle. In addition, a phenol resin molding material is generally injection-molded, in which a resin is injected into a mold cavity at a high pressure and curing is performed while applying pressure for a certain period of time. Therefore, residual stress is generated in the molded product shaped in the mold, and in the cooling process after the mold is taken out from the mold, when the residual stress diffuses, the molded product may be warped or deformed. Conventionally, as a method for solving these problems, the melt viscosity of the molding material is decreased, that is, the fluidity is increased and the injection pressure is decreased, but the curing speed of the molding material becomes slow, so the molding cycle Is quite long and difficult to put to practical use.

[0003]

The present invention has been completed as a result of various studies in order to obtain a phenol resin molding material which is molded at a low pressure and has a high curing rate. An object of the present invention is to provide a phenolic resin molding material which is extremely excellent in mold filling property and curability in molding.

[0004]

According to the present invention, a resin component consisting of a crystalline phenol compound having two or more nuclear bodies and a phenol resin, hexamethylenetetramine, and an average particle size of 10 are used.
Phenolic resin molding material for low-pressure molding, characterized in that a composition obtained by previously melt-mixing a fine-particle inorganic powder of 0 nm or less and a filler are mixed, and the mixture is kneaded, and the above-mentioned compound. In addition to the above, it is a phenol resin molding material for low-pressure molding, which is obtained by mixing and kneading a compound having two or more hydroxyl groups in the benzene ring.

In the present invention, the crystalline phenol compound having two or more nuclides is crystalline at room temperature, has a clear melting point, and becomes a low-viscosity liquid when melted to cure a phenol resin such as hexamethylenetetramine. A phenol compound having two or more nuclei which is hardened by reacting with the agent. Examples of the crystalline phenol compound having two or more nuclei include bisphenol A, bisphenol F, and bisphenol A.
There are bisphenol compounds such as D, bisphenol Z and bisphenol S and their derivatives, biphenol and its derivatives, and trinuclear or tetranuclear phenol compounds represented by the following chemical formulas.
More than one species can be used.

[0006]

[Chemical 1]

In the present invention, 2 hydroxyl groups are added to the benzene ring.
As the compound having two or more, one kind or two or more kinds such as resorcin, hydroquinone, catheter, phloroglucinol, pyrogallol and derivatives thereof can be used. As the phenol resin of the present invention, a normal novolac type phenol resin obtained by the reaction of phenols and formaldehyde can be used.
In the present invention, the crystalline phenolic compound having a binuclear body or more is a phenolic resin molding material that is solid at room temperature, and is melted more quickly due to plasticization during injection molding to have a low viscosity.
Used to impart the property of being moldable at low pressure. The compound having two or more hydroxyl groups on the benzene ring is used for imparting the property of improving the curing rate while maintaining the low viscosity without impairing the above-mentioned properties of the crystalline phenol compound having two or more nuclei. In addition, a usual novolac type phenol resin is appropriately blended and used for adjusting viscosity and curability, if necessary.

Therefore, in the present invention, the compounding ratio of the crystalline phenol compound (A) having two or more nuclei and the phenol resin (B) can be arbitrarily selected, but preferably A / B = 80/20. It is 30/70. If the amount of component A is small, the crystallinity characteristics as described above cannot be sufficiently exhibited, and if the amount is large, curing will be slow. Further, as the blending ratio of the component B increases, the viscosity of the molten resin increases and the curability is improved.
Within the above range, it may be appropriately blended depending on the purpose. Furthermore, a compound (C) having two or more hydroxyl groups on the benzene ring
Is used for accelerating the curing, but the preferable blending ratio is the total amount of the above-mentioned A component and B component / C component = 9.
It is 7/3 to 90/10. When the amount of C component is small, the effect of accelerating the curing is small, and when it is large, the curability becomes poor.

Hexamethylenetetramine (hereinafter referred to as hexamine), which is a curing agent for the phenol resin molding material of the present invention, is melt-mixed with the resin component in advance. The proportion of hexamine is 7 to 30% by weight, preferably 10 to 25% by weight, based on the phenol resin component (the total of the components A and B). If the amount is less than 7% by weight, the curing is not sufficiently performed, and if the amount is more than 30% by weight, the curability is not improved, and conversely the characteristics of the molded product (for example, mechanical strength) are deteriorated. In the present invention, the composition in which the resin component and hexamine are melt-mixed is a method in which hexamine is mixed with the resin component which is heated and melted at a temperature of 30 to 60 ° C. by a mixer such as a kneader, a pressure kneader, or a Henschel mixer. Can be obtained by Alternatively, the phenol resin can be obtained by a method of dissolving the phenol resin in a solvent such as methanol, mixing and dissolving hexamine, and then removing the solvent to perform melt integration.

Fillers used in the phenol resin molding material of the present invention include wood powder, pulp powder, various pulverized woven fabrics, phenol resin laminates, organic substances such as pulverized powder of molded products, silica, alumina, and water. It is possible to use at least one kind of inorganic powder such as aluminum oxide, glass, talc, clay, mica, calcium carbonate and carbon, inorganic fiber such as glass fiber, carbon fiber and asbestos. The compounding ratio in the phenol resin molding material of the present invention is such that the hexa-containing phenol resin is 20 to 7
0% by weight and 80 to 70% by weight of filler. Further, various additives such as a lubricant, a colorant, a curing accelerator, and a flame retardant can be appropriately added to the phenol resin molding material of the present invention.

The phenol resin molding material of the present invention comprises a composition obtained by melt-mixing a resin component and hexamine, a filler,
It can be manufactured by blending other additives, kneading with a roll mill, a twin-screw kneader, and pulverizing. When a compound having two or more hydroxyl groups in the benzene ring is blended, it may be melt-mixed with the resin component and hexamine in advance, or may be kneaded with a filler in the next step. The compounding of such a compound is preferable in order to maintain good fast curing property and low pressure moldability.

[0012]

The phenol resin molding material of the present invention is excellent in curability because hexamine is dissolved or uniformly dispersed in the resin component by previously melt-mixing the resin component and hexamine. In addition, 2 hydroxyl groups on the benzene ring
When the compound containing one or more compounds is contained, the curability is further improved. When it contains a crystalline phenol compound having two or more nuclei, it has a low melt viscosity, a good fluidity, and is very suitable for low pressure molding. That is, the phenol resin molding material of the present invention melts very quickly in the plasticizing step at the time of molding to have a low viscosity and has good fluidity, so that it can be formed in a mold cavity at a low pressure without applying extra pressure. It can be filled and can be quickly cured to obtain a molded article having good characteristics.
Further, it is possible to shorten the forming cycle, reduce burrs, improve the life of the mold, and reduce the weight of the mold.

[0013]

EXAMPLES The present invention will be described below with reference to examples and comparative examples. Here, "parts" represent parts by weight. << Example 1 >> 22 parts of a novolac type phenol resin (number average molecular weight 800), 19 parts of bisphenol F and 7 parts of hexamine were melt-mixed in a roll mill at 50 ° C. for 30 minutes, then taken out and pulverized. 3 parts of resorcin, 3 parts of calcium hydroxide, 30 parts of wood flour, 11 parts of calcium carbonate,
Mix 3 parts of release agent, melt and knead with 2 roll mill,
After cooling, it was pulverized 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 bisphenol F in Example 1 was replaced with trisphenol. <Example 3> A phenol resin molding material was obtained in the same manner as in Example 1 except that the resorcinol of Example 1 was replaced with phloroglucinol. <Example 4> Example 1 was repeated except that resorcin was not blended.
A phenol resin molding material was obtained in the same manner as in.

Comparative Example 1 Novolak-type phenol resin (number average molecular weight 800) 44 parts, hexamine 7 parts, calcium hydroxide 3 parts, wood flour 30 parts, calcium carbonate 11
Parts and 3 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 viscosities of the phenol resins used in Examples and Comparative Examples and the properties of the obtained phenol resin molding materials.

[0015]

[Table 1]

In Table 1, the viscosity of the resin is the high temperature type cone plate viscometer (made by Cordix, CCV-1S).
Type). The fluidity of the molding material is a Koka type flow tester (CFT-500C manufactured by Shimadzu Corporation).
It shows the melt viscosity measured by. The curability indicates the Bacol hardness measured by filling a mold at 175 ° C. with a molding material preheated to 105 ° C. by a transfer molding machine and taking out after 40 seconds for measurement. The burr generation state was measured by molding with a transfer molding machine under the following conditions. (Molding Conditions by Transfer Molding Machine) 20 g of tableted phenol resin molding material was preheated to about 100 ° C., and molded at 175 ° C. for 3 minutes using a transfer molding die having the shape shown in FIG. The moldability was determined by visually checking the filling property into the rectangular cavity and the burr in the air vent. From Table 1, the phenol molding materials obtained in each of the examples have lower viscosity and excellent curability than the conventional phenol resin molding materials of the comparative examples. The filler is good, and the occurrence of burrs during molding is extremely small.

[0017]

As is apparent from the above examples, the phenol resin molding material of the present invention has a low viscosity when melted and is excellent in curability. It is possible to achieve both mold filling and burr suppression. Therefore, it can be widely used as a phenol molding material having excellent moldability, and a molding cycle can be shortened and a die life can be improved.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a transfer molding die used in an example.

FIG. 2 is a sectional view taken along line AA of FIG.

[Explanation of symbols]

 1 Circular Cavity 2 Square Cavity 3,4,5 Air Vent 6 Pot 7 Plunger

Claims (2)

[Claims] 1. A composition and a filler in which a resin component composed of a crystalline phenol compound having two or more nuclear bodies and a phenol resin, hexamethylenetetramine, and finely divided inorganic powder having an average particle diameter of 100 nm or less are melt-mixed in advance. A phenol resin molding material for low-pressure molding, which is prepared by mixing as a component and kneading the mixture. 2. The phenol resin molding material for low-pressure molding according to claim 1, wherein the compound contains a compound having two or more hydroxyl groups in the benzene ring and is kneaded.