JPH02258860A - Phenolic resin molding material - Google Patents

Abstract

PURPOSE:To obtain the subject material having remarkably improved moldability without deteriorating mechanical properties and various other characteristics by using a specific filler. CONSTITUTION:The objective phenolic resin molding material is produced by compounding 5-70wt.% of flaky glass. The flaky glass is preferably made of E glass and preferably glass fiber especially having a length of <=1,500mum is added thereto.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is a molded product that is shaped like a plate or has a shape that is not symmetrical in the top, bottom, left and right, and is prone to warping, and can be molded with extremely little warping even when used at high temperatures. This relates to phenolic resin molding materials used in products.

(Conventional technology) Phenolic resin molding materials have traditionally been made of pulp, cotton waste,
Organic fillers such as cloth chips and inorganic fillers such as glass, calcium carbonate, clay, mica, diatomaceous materials, etc. have been widely used. For glass, mainly chipped strand glass fibers are mainly used.

Among such fillers, when organic fillers such as wood flour or cotton waste are used, the warpage is greater than when inorganic fillers are used, and fibrous fillers tend to warp more easily than granular fillers.

On the other hand, molded products made from phenolic resin molding materials that do not contain fibrous fillers such as glass fibers have the disadvantage of being brittle and easily broken, and are limited to thick molded products or molded products that do not require high mechanical strength. Phenolic resin molding materials used for ordinary molded products contain 5% (by weight, the same applies hereinafter) to 10% or more of fibrous fillers such as wood flour, cotton, and glass fiber.

Therefore, when manufacturing a molded product that is plate-shaped or has a shape that is prone to warping without being oriented vertically or horizontally, it is necessary to improve the warping by creating a temperature difference in the mold during molding, or by using a jig after molding. The warpage is forcibly improved.

If warpage still occurs, the warpage is forcibly improved by using a jig at an appropriate temperature of up to 200° C. for a considerable period of time. These steps require more time and manpower than necessary and are very inconvenient for manufacturing molded products.

If you change the shape of the molded product to be symmetrical both vertically and horizontally,
It is clear that the warpage will be extremely reduced, but in practice there are very few cases where it is possible to change the shape to such a shape.There are cases where either the top, bottom or left or right sides are symmetrical, but in most cases it is a non-symmetrical shape. It is a molded product. Moreover, injection molding machines have become popular in recent years, and fibrous fillers are oriented and easily warped during injection molding, so there is an increasing demand for phenolic resin molding materials with less warp.

(Problems to be Solved by the Invention) An object of the present invention is to create a phenolic resin molding material with extremely excellent moldability without deteriorating mechanical properties and other properties by using a specific filler. It is on offer.

(Means for Solving the Problems) The present invention is a phenolic resin molding material containing 5 to 70% of glass flakes.

The flaky glass used in the present invention has a thickness of 1
It is a flaky thin film glass with a particle size of ~10μ and a particle size of about 10 to 2000 tt, and is usually obtained by crushing a thin plate glass of the above thickness. Although the type of glass does not need to be specified, E glass is preferred.

Examples of such glass flakes include "micro glass flakes" manufactured by Nippon Sheet Glass.

``Micro Glass Flake'' is commercially available in three grades with an average thickness of about 4μ and different particle sizes.

The thinner the glass flakes are, the better, but if the thickness is less than 1 μm, they tend to break easily and are difficult to manufacture.

If it is 10 μ or more, the flaky effect will be reduced.
If the particle size is less than 10μ, the effect as a flake is small, and the larger the particle size, the greater the effect on warpage.
It is difficult to manufacture a material with a diameter of 00μ or more.

It is preferable that glass flakes be surface-treated with a silane coupling agent, but raw materials used with glass flakes that may be left untreated include phenolic resins, modifiers, and other fillers. , accelerators, lubricants, colorants, plasticizers, etc.

Phenolic resins include one-step resins such as solid resols, two-step resins with a curing side such as novolak and hexamethylenetetramine, or modified with aniline, resorcinol, alkylphenols, drying oils, alkylbenzene resins, melamine, furfural, etc. Modified resins are used.

Examples of modifiers to be added to the phenolic resin molding material include synthetic resins other than phenolic resins such as melamine resins, alkylbenzene resins, and NBR, or rubbers.

The filler used with the glass flakes may not be used, but general organic fillers and inorganic fillers can be used.

Organic fillers have low heat resistance and cause molded products to warp when heated, so depending on the application, the smaller the amount, the better.

Fibrous fillers such as glass fiber are effective in improving the strength of molded products, but they can cause warping, so care must be taken when blending them.From the balance between zero strength and warping, usually
In order to maintain strength, the amount of fibrous filler blended is 10% or less, preferably 5% or less, based on the total molding material, or 20% or less, preferably 10% or less based on the total filler. The fibrous filler to be added is preferably glass fiber, particularly glass fiber having a length of 1500 μm or less.

The phenolic resin molding material may be produced by granulation using a high-speed rotating mixer, or by kneading using a conventional mixing roll or twin-screw extrusion kneader.

The method for molding the molding material according to the present invention can be applied to injection molding, transfer molding, compression molding, extrusion molding, etc., and is not limited to any one of them.

(Function) Warpage of phenolic resin molded products is caused by shrinkage that occurs as the phenol resin molding material hardens.

Generally, phenolic resin molding materials containing organic fillers are
The organic filler itself often contains a large amount of water and has low heat resistance, so it shrinks greatly during curing and is prone to warping.

On the other hand, phenolic resin molding materials containing inorganic fillers have a low volatile content and high heat resistance, so they shrink less during curing and exhibit less warpage than those containing organic fillers.

However, if a fibrous filler is blended for practical mechanical strength, the fibrous filler will be oriented during molding, and if there is asymmetry in the vertical or horizontal directions or in the shape of the molded product, the asymmetry will occur. It is thought that the degree of shrinkage varies depending on the area, leading to warping of the entire molded product.

The flake-shaped glass in the present invention is completely different in shape from the chopped strand glass fibers and bead-shaped glass used conventionally, and is thin and planar. Mica has been known as such a planar filler for a long time, but since mica itself has a low strength and has a layered structure, phenolic resin molding materials that mainly use mica can be used in the form of a plate or in the top, bottom, left and right. Molding an asymmetrical molded product that easily warps has the disadvantage that it is easily broken and brittle.

The glassy flakes of the present invention have sufficient bending strength, and when used in a phenolic resin molding material, molded products that do not crack or chip and have mechanical strength that can withstand practical use can be obtained.

Moreover, since it is not a fibrous filler, it is less likely to be oriented during molding (and a molded product with extremely little warping can be obtained).

By blending only inorganic fillers without using organic fillers, it is possible to obtain molded products with high heat resistance that can be used at a maximum temperature of about 180° C. and have little warpage.

(Example) The raw materials shown in Table 1 were kneaded in a predetermined composition using a mixing roll and pulverized. The resulting molding material was measured for warpage, bending strength according to JIS K 6911, bending elastic modulus, and Charpy impact strength.

Warpage was determined by transfer molding a 100 x 200 x 2 (am) plate-shaped product for 3 minutes at 175"C.
After baking at ℃ for 10 hours, the height was determined.

The measurement results are also shown in Table 1.

As shown in the Examples in Table 1, when glass flakes were used, good molded products with a predetermined strength and little warpage were obtained.

(Effects of the Invention) According to the present invention fi, the same high yield as before can be obtained without changing the existing method for producing a phenolic resin molding material. In addition, it is not necessary to change the shape of the mold, and a molded product with extremely little warpage can be obtained without performing any steps such as using a forced jig after molding. Therefore, it has become possible to easily manufacture plate-like molded products or molded products that are asymmetrically warped vertically and horizontally, which could not be manufactured in the past, especially molded products for applications that are used at high temperatures, and industrial phenol It is suitable as a resin molding material.

Claims (1)

[Claims] (1) A phenolic resin molding material containing 5 to 70% by weight of glass flakes.