JPH04222853A - Phenolic resin molding material for injection molding - Google Patents

Abstract

PURPOSE:To obtain a phenolic resin molding material for injection molding having excellent fluidity and heat stability in a cylinder and remarkably improved in impact resistance of molding. CONSTITUTION:The objective phenolic resin molding material obtained by adding alpha, alpha-dimethoxy-p-xylene to a mixture consisting essentially of phenolic resin, hexamethylene tetramine and glass fiber, having 30-70wt.% glass fiber content and having 0.3-3.0mm number-average fiber length of glass fiber. The molding material can remarkably improve heat stability in a cylinder and impact resistance of the molding.

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 for injection molding which has excellent fluidity and in-cylinder thermal stability, and which can significantly improve the impact resistance of molded products.

0002

BACKGROUND OF THE INVENTION In general, phenolic resin molding materials for injection molding must have sufficient fluidity and in-cylinder thermal stability for stable continuous molding. In order to improve this fluidity and in-cylinder thermal stability, α,α'-dimethoxy-p-xylene is added to the phenolic resin molding material, which impairs the hardening properties after shaping in the mold. It has been disclosed that the fluidity and in-cylinder thermal stability can be improved without any
3-264310).

On the other hand, in order to improve the impact resistance of phenolic resin molded articles, it is common to use glass fiber as a filler, and the longer the glass fiber, the higher the impact resistance. Therefore, in order to obtain a phenolic resin molded product with high impact resistance, a phenolic resin molding material using long glass fibers is preferable. However, if the glass fibers present in the molding material are long, during injection molding, the molding material receives shearing force from the rotation of the screw during plasticization measurement and generates heat, resulting in a decrease in fluidity and in-cylinder thermal stability due to the curing reaction. However, there were major problems in achieving stable continuous molding.

[0004] From the above, a phenolic resin molding material for injection molding using glass fiber as a filler, which has excellent fluidity and in-cylinder thermal stability and has high impact resistance for molded products, has not yet been found. That was the reality.

[0005]

[Problems to be Solved by the Invention] The object of the present invention is to provide a phenolic resin molding material for injection molding, which uses glass fiber as a filler, has excellent fluidity, thermal stability inside the cylinder, and has excellent impact resistance. It is about providing.

[0006]

[Means for solving the problem] As a result of intensive studies, the present inventors added α,α'-dimethoxy-p-xylene to a mixture whose main components are phenolic resin, hexamethylenetetramine, and glass fiber. It has been discovered that a phenolic resin molding material for injection molding, which contains a specific amount of glass fibers and glass fibers with an adjusted number average fiber length, can solve the above problems, and the present invention reached.

[0007] That is, the present invention provides phenolic resins,
In a phenolic resin molding material for injection molding, which is obtained by adding α,α'-dimethoxy-p-xylene to a mixture containing hexamethylenetetramine and glass fiber as main components,
The content of glass fiber in the molding material is 30 to 70% by weight, and the number average fiber length of the glass fiber is 0.3 to 3.0 mm.
A phenolic resin molding material for injection molding characterized by
When mixing and dispersing α'-dimethoxy-p-xylene, 4 to 15 parts by weight of an organic solvent and/or water are added to 100 parts by weight of each component in total and kneaded. It is also a method for producing a phenolic resin molding material for injection molding.

[0008] The contents of the present invention will be explained in detail below.

The phenolic resin used in the present invention may include all phenolic resins that can be cured with hexamethylenetetramine.
For example, phenols such as phenol, cresol, xylenol, resorcinol, bisphenol A, p-butylphenol, p-octylphenol, and styrenated phenol, formalin, paraformaldehyde,
Phenolic resins obtained by reacting aldehydes such as trioxane and furfural using an acidic or basic catalyst, phenols and p-xylylene dihalides such as α,α'-dichloro-p-xylene, α,
There are phenol aralkyl resins derived from p-xylylene dialkyl ethers such as α'-dimethoxy-p-xylene, etc., and these resins can be used alone or in combination of two or more.

In the present invention, the amount of hexamethylenetetramine used is 3 to 20 parts by weight, preferably 6 to 15 parts by weight, based on 100 parts by weight of the phenolic resin. 3
If it is less than 20 parts by weight, the molded product will have poor rigidity when heated, and if it exceeds 20 parts by weight, blistering will occur on the surface of the molded product, which is not preferable.

The content of glass fiber in the present invention in the molding material is 30 to 70% by weight, and the number average fiber length is 0.
．． It is 3 to 3.0 mm, preferably 0.4 to 2.5 mm. If the content of glass fiber is less than 30% by weight, the reinforcing effect of glass fiber as a filler will not be achieved, and the impact resistance of the molded product will be low; if it exceeds 70% by weight, fluidity will be poor and stable continuous molding will not be possible. . Furthermore, if the number average fiber length of the glass fiber is less than 0.3 mm, the impact resistance of the molded product will be low;
If it exceeds mm, fluidity and in-cylinder thermal stability will decrease, causing problems in molding.

In the present invention, α,α'-dimethoxy-
The amount of p-xylene used is 1 to 15 parts by weight, preferably 2 to 10 parts by weight, per 100 parts by weight of the phenolic resin. If it is less than 1 part by weight, the effect of improving fluidity and in-cylinder thermal stability is poor, and if it exceeds 15 parts by weight, backflow will be severe during injection molding and the appearance of the molded product will be impaired, which is not preferable.

In the present invention, additives such as pigments and lubricants may be added as necessary. Compounding agents include pigments, lubricants, conductivity imparting agents, antioxidants, curing accelerators, synthetic resins such as epoxy resins, silane coupling agents, and other materials used in normal phenolic resin molding materials. .

The phenolic resin molding material for injection molding of the present invention is produced by adding α,α'-dimethoxy-p-xylene to a mixture containing a phenol resin, hexamethylenetetramine, and glass fiber as main components, and then using a known method. That is, it is produced by kneading with a roll, kneader, twin-screw kneading extruder, or the like.

[0015] As a method for adjusting the number average fiber length of the glass fibers in the molding material to 0.3 to 3.0 mm, a wet kneading method using an organic solvent or water is used to prevent breakage of the glass fibers during kneading. It is also desirable because it can be kneaded uniformly. The glass fibers used during wet kneading include chopped strands with a diameter of 6 to 13 mm and a cut length of 1.5 to 12 mm, which are used in ordinary phenolic resin molding materials.

[0016] Examples of organic solvents used in wet kneading include alcohols such as methanol and ethanol, ketones such as acetone and methyl ethyl ketone, furfural, and styrene, and these may be used alone or in combination of two or more. can. The amount of organic solvent or water used in wet kneading is based on 100 parts by weight of the mixture containing phenolic resin, hexamethylenetetramine, glass fiber as the main components, and α,α'-dimethoxy-p-xylene. , 4 to 15 parts by weight. If it is less than 4 parts by weight, the glass fibers will break during kneading, and if it exceeds 15 parts by weight, the phenolic resin and glass fibers will not be uniformly dispersed.

The kneading temperature and kneading time vary depending on the kneading machine used, the type and amount of organic solvent used, etc.
Although not particularly limited, each room temperature to 120℃
(room temperature to boiling point for organic solvents with a boiling point of 120°C or lower), preferably 1 to 30 minutes. If the kneading temperature exceeds 120°C, a curing reaction between the phenol resin and hexamethylenetetramine will occur, which is undesirable. In addition, if the kneading time is less than 1 minute, the dispersion of the phenolic resin and glass fibers will be poor.
If the time exceeds 30 minutes, it is undesirable that the glass fibers will be significantly broken.

The mixture kneaded above is shaped into a sheet using a roll or an extruder, and then pulverized using a pulverizer or cut using a cutter type granulator such as a sheet pelletizer to obtain a molding material. I can do it.

[0019]

[Examples] The present invention will be specifically explained below with reference to Examples and Test Examples.

(Examples 1 to 5) As shown in Table 1, phenol novolac resin (manufactured by Mitsui Toatsu Chemical Co., Ltd., Novolac #1000HS and #2000), phenol aralkyl resin (manufactured by Mitsui Toatsu Chemical Co., Ltd., Mirex XL- 225)
, hexamethylenetetramine, magnesium stearate, and carbon black were crushed and mixed, and charged into a kneader, and then α,α'-dimethoxy-p-xylene, acetone, glass chopped strands with a diameter of 11 μm and a cut length of 6 mm, and γ-amino Propyltriethoxysilane was added and kneaded. The kneaded material was shaped into a sheet, then pulverized and granulated using a Henschel mixer, and dried to obtain a molding material. The number average glass fiber length in the obtained molding material is also listed in Table-1.

(Comparative Examples 1 to 4) Molding materials were obtained in the same manner as in Examples 1 to 5. (Test Example) The following tests were conducted on the molding materials obtained in Examples 1 to 5 and Comparative Examples 1 to 4. ■Fluidity, thermal stability inside the cylinder Using an injection molding machine IR45P manufactured by Toshiba Machinery Co., Ltd., the molding material was weighed at a cylinder front temperature of 95°C, a cylinder rear temperature of 60°C, and a screw rotation speed of 50 rpm, and for a certain period of time immediately after the measurement. The molding material was retained in the cylinder, and a JIS family mold (with a cavity capacity of 42 cm3) set at 180°C and an injection pressure of 800 kg/cm2 was used.
(for bending strength, Charpy impact strength, and water absorption test pieces) was injected into a mold. At this time, the maximum residence time without causing filling defects was defined as the thermal stability time. (2) Impact resistance Charpy impact strength was measured according to JIS K6911 using the Charpy impact strength test piece obtained by molding under the above conditions.

The test results of ■ and ■ are also listed in Table 1.

[0023]

[Table 1]

[0024]

[Effects of the Invention] Since the present invention has the above-described structure, it has two contradictory properties that are not present in conventional phenolic molding materials for injection molding.
It is possible to achieve both of the following properties: fluidity, in-cylinder thermal stability, and impact resistance of molded products.

Claims (2)

[Claims] Claim 1: A mixture containing phenolic resin, hexamethylenetetramine, and glass fiber as main components contains α, α'
- In a phenolic resin molding material for injection molding containing dimethoxy-p-xylene, the content of glass fiber in the molding material is 30 to 70% by weight, and the number average fiber length of the glass fiber is 0.3. A phenolic resin molding material for injection molding, characterized in that the thickness is 3.0 mm. Claim 2: In the production of a phenolic resin molding material for injection molding, a mixture containing a phenolic resin, hexamethylenetetramine, glass fiber as the main components, and α, α
A claim characterized in that when mixing and dispersing '-dimethoxy-p-xylene, 4 to 15 parts by weight of an organic solvent and/or water are added to 100 parts by weight of each component in total and kneaded. Item 1. A method for producing a phenolic resin molding material for injection molding according to item 1.