JPH07278409A - Phenolic resin molding material - Google Patents

Abstract

PURPOSE:To obtain the subject material which can give a molding improved in dimensional accuracy by mixing a mixture of a bisphenol F compound or a bisphenol A compound with a novolac phenolic resin in a specified weight ratio with hexamethylenetetramine and a filler. CONSTITUTION:A bisphenol F compound or a bisphenol A compound (A) is mixed with a novolac resin (B) having an ortho isomer/para isomer ratio of 1.0-2.5 and a number-average molecular weight of 700-1000 in an (A)/(B) weight ratio of 10/90 to 30/70. A curing agent (C) (e.g. hexamethylenetetramine) in an amount of about 10-25wt.% based on the total of components A and B is added to the obtained mixture, 75-40wt.% filler (D) (e.g. silica or glass fiber) based on 25-60wt.% total of components A to C is added to the mixture of components A to C, and a mold release, a pigment, etc., are added to the resultant mixture, and the final mixture is melt-kneaded with e.g. a roll mill, cooled and ground to obtain the objective material. This material is molded into a product of good dimensional accuracy.

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 having excellent dimensional accuracy of a molded product.

[0002]

BACKGROUND OF THE INVENTION Phenolic resins are used in a wide range of applications such as automobile parts, electronic parts, electric parts, and mechanical parts because of their excellent heat resistance, electric performance and mechanical performance. In recent years, the demand for dimensional performance has increased for phenol resin products as the precision of products has increased. Therefore, it has become necessary to perform molding with high precision. However, a phenol resin molding material is generally subjected to high-pressure injection molding, 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 after the residual stress is taken out from the mold, when the residual stress diffuses in the cooling process, the molded product is warped or deformed. Since the resin is injected into the mold cavity at high pressure,
The gaps between the molds cause variations in the dimensional accuracy of the molded product.

Conventionally, as a method for solving these problems, the melt viscosity of the molding material is lowered, that is, the fluidity is increased,
Molding has been carried out at a low injection pressure. However, although the burr is less likely to occur, the hardening of the molding material is slowed down, so that the molding cycle becomes long and it is difficult to put into practical use.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a phenol resin molding material having excellent filling properties and fast curing.
It has been completed as a result of various studies, and its purpose is to develop a phenol resin molding material that is extremely excellent in mold filling and curability in low-pressure molding and has extremely good dimensional accuracy of phenol resin trial products. It is in the place of providing.

[0005]

According to the present invention, a resin component composed of a bisphenol F compound or a bisphenol A compound (A) and a novolac type phenol resin (B), hexamethylenetetramine, and a filler are essential components. It is a characteristic phenol resin molding material. In the present invention, bisphenol F compound or bisphenol A
The compound is used in order that the phenol resin molding material is solid at room temperature and is rapidly melted to have a low viscosity due to plasticization at the time of injection molding so that it can be molded at a low pressure.

In the present invention, the compounding ratio of the bisphenol F compound or bisphenol A compound (A) and the novolac type phenol resin (B) is A / B = 10/90.
It is 30/70. If the amount of component A is less than 10% by weight, the above-mentioned characteristic of crystallinity cannot be sufficiently exhibited, and if it exceeds 30% by weight, curing tends to be delayed. Further, as the blending ratio of the component B increases, the melt viscosity increases and the curability improves, so a proper blending ratio can be selected within the above range depending on the purpose.

In the present invention, when a novolak type phenol resin having an ortho-para ratio of 1.0 to 2.5 obtained by the reaction of phenols and formaldehyde is used as the phenol resin, the viscosity at the time of melting is Relatively low,
The number average molecular weight is preferably 700 to 1100 because it is fast-curing, and the number average molecular weight is preferably from the viewpoint of achieving both fast-curing property and thermal stability. On the other hand, the ortho-para ratio is 0.6-0.
When the novolac type phenol resin of No. 9 is used, the heat stability is relatively good and the moldability is stable, so that it is suitable for molding a large-capacity molded product, and the molecular weight is 600 in terms of number average molecular weight.
It is preferable that those having a molecular weight of up to 1300 have good moldability and filling properties.

When it is necessary to increase the curing rate in addition to the above components, it is preferable to incorporate a compound (C) containing two or more hydroxyl groups in the benzene ring. Such C component includes resorcin, hydroxin, catechol, phloroglucinol, pyrologlucinol,
One kind or two or more kinds such as pyrogal and derivatives thereof can be used. If the amount of component C is too large, the curability will be poor.
It is 0 to 10% by weight based on the total amount of the components.

The compounding ratio of hexamethylenetetramine (hereinafter referred to as hexamine), which is the curing agent for the phenol resin molding material of the present invention, is 1 with respect to the total amount of the components A and B.
It is 0 to 25% by weight, preferably 13 to 20% by weight.
If it is less than 10% by weight, the curing will not proceed sufficiently, and if it is more than 25% by weight, the curability will not be further improved, and on the contrary, the characteristics of the molded article (for example, mechanical characteristics) will be deteriorated.

As the filler used in the phenol resin molding material of the present invention, wood powder, pulp powder, various pulverized woven fabrics, organic materials such as pulverized powder of phenol resin laminates and molded products, silica, alumina , Aluminum hydroxide, glass, talc, clay, mica, calcium carbonate, inorganic powder such as carbon, glass fiber, carbon fiber, inorganic fiber such as asbestos, etc., and one or more of these are used. be able to.

The compounding ratio of the phenol resin molding material of the present invention is usually 25 to 60% by weight of the resin component containing hexamine and 75 to 40% by weight of the filler. Further, various additives such as a lubricant, a colorant, a curing accelerator, and a flame retardant can be appropriately blended in the phenol resin molding material of the present invention. The phenol resin molding material of the present invention can be manufactured by blending a resin component, hexamine, a filler, and other additives, kneading with a roll mill, a twin-screw kneader, or the like and pulverizing.

[0012]

According to the present invention, a resin component comprising a bisphenol F compound or a bisphenol A compound and a novolac type phenol resin has a low viscosity when melted, and a resin component containing hexamine or hexamine and a compound containing two or more hydroxyl groups in the benzene ring. It has excellent curability because it is blended in a proper ratio. 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 a good fluidity, so that the pressure inside the cavity of the mold can be reduced without applying extra pressure. It is possible to obtain a product with extremely good dimensional accuracy of the molded product, because it can be filled in the mold and distortion of the mold can be suppressed. Furthermore, it is possible to reduce the amount of burrs generated during molding, 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 >> 30 parts of novolak type phenolic resin (number average molecular weight 900) having an ortho-para ratio of 0.8, 8 parts of bisphenol F, 7 parts of hexamine, 1 part of magnesium hydroxide
Parts, 50 parts of glass fiber, 4 parts of release agent and pigment are mixed, and
The mixture was melt-kneaded with this roll mill, cooled, and then pulverized to obtain a phenol resin molding material.

Example 2 Novolac-type phenolic resin (number average molecular weight 800) with an ortho-para ratio of 2.1 26
Parts, bisphenol F 11 parts, hexamine 7 parts, magnesium hydroxide 1 part, resorcin 1 part, glass fiber 50
Parts, a release agent and a pigment were mixed in 4 parts. A phenol resin molding material was obtained in the same manner as in Example 1 except for the above.

<< Comparative Examples 1 and 2 >> Ortho-para ratio of 0.8
Novolak type phenolic resin (number average molecular weight 900)
38 parts, 7 parts of hexamine, 1 part of magnesium hydroxide, 50 parts of glass fiber, 4 parts of a release agent and a pigment were mixed, melt-kneaded with a two-roll mill, and cooled and ground to obtain a phenol resin molding material.

Table 1 shows the viscosities of the phenolic resins used in Examples and Comparative Examples and the characteristics of the phenolic resin molding materials. In Comparative Examples, Comparative Example 1 is a case of molding at the same gauge pressure of 50 kg / cm ^{2 as} that of the Example, and Comparative Example 2 is a case of increasing the gauge pressure to 110 kg / cm ² . As is clear from the results in Table 1, the phenolic resin molding materials obtained in each of the examples have lower viscosity and excellent curability than the conventional phenolic resin molding materials of the comparative examples. The filling property is good, and the dimensional accuracy of the molded product is extremely good.

[0017]

[Table 1]

The method of measuring the characteristics in Table 1 is as follows. 1. Flowability of molding material: Melt viscosity measured by a Koka type flow tester (CFT-500C manufactured by Shimadzu Corporation). 2. Curability: The barcol hardness is measured by filling a mold at 175 ° C. with a molding material preheated to 105 ° C. by a transfer molding machine, taking out a molded product after 30 seconds, and measuring it. 3. Moldability: The molded product shown in FIG. 1 was molded with an injection molding machine, and the filling property into the cavity was visually determined. After cooling the molded product, the dimensions of the molded product were measured, the standard deviation value (σ) was determined, and the dimensional accuracy of the molded product was determined.

[0019]

EFFECTS OF THE INVENTION As will be apparent from the following examples, the phenol resin molding material of the present invention has a low viscosity when melted and is excellent in curability, so that it is possible to perform low pressure molding, and It is possible to achieve both good mold filling properties and high dimensional accuracy of molded products. Therefore, it can be widely used as a phenolic resin molding material having excellent moldability, and it is possible to suppress the occurrence of burrs and improve the mold life.

[Brief description of drawings]

1A and 1B are molded products molded in Examples, in which FIG. 1A is a front view, FIG. 1B is a side view, and FIG. 1C is a plan view.

Claims (3)

[Claims] 1. A resin component consisting of a bisphenol F compound or a bisphenol A compound (A) and a novolac type phenol resin (B), A / B = 10/90 to 30/70, hexamethylenetetramine, and a filler are essential. A phenol resin molding material characterized by being used as a component. 2. A novolac type phenolic resin is an ortho
A phenol resin molding material having a para ratio in the range of 1.0 to 2.5. 3. A novolac type phenol resin is an ortho
A phenol resin molding material having a para ratio in the range of 0.6 to 0.9.