JPH1149928A - Phenolic resin molding material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide phenolic resin molding materials having superior moldability in injection molding due to a high flowability and heat stability in the molten state and excellent curing characteristics at high temperatures. SOLUTION: Phenolic resin molding materials comprise 10-45 pts.wt. novolak- type phenolic resin (A) having a ratio of ortho-linkage to para-linkacue (O/P), relative to the methylene linkage with the phenolic nucleus, of 1.5-2.5 and a number average molecular weight of 350-600, 100 pts.wt. novolak-type phenolic resin (B) having an 0/P of 0.7-1.0 and a number average molecular weight of 700-1,000, hexamethylenetetramine and an filler.

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 heat stability and curability.
Particularly, the present invention provides a phenolic resin molding material having excellent thermal stability in a cylinder of an injection molding machine.

[0002]

2. Description of the Related Art Phenolic resin molding materials have an excellent balance of heat resistance, electrical properties, mechanical properties, dimensional stability, etc.
It is used in a wide range of fields including electric components.
Generally, these are molded by injection molding, but in the molten state plasticized at 80 to 120 ° C. in the cylinder of the injection molding machine, the viscosity increases due to the progress of the curing reaction of the resin and the property of losing fluidity have. When injection molding a conventional phenolic resin molding material, the molding material melted in the cylinder of the injection molding machine has poor thermal stability,
There is a problem that the appropriate condition width is extremely narrow.

Conventionally, various methods have been known to solve these problems, such as reducing the melt viscosity of a molding material, that is, increasing the fluidity. In these cases, however, the thermal stability in the molten state is reduced. If the content is improved, the curing is slowed, so that the molding cycle is lengthened, and it is difficult to put to practical use.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made as a result of various studies to solve these problems, and it is an object of the present invention to provide a heat stability in a molten state in a cylinder during injection molding. And a phenolic resin molding material having excellent curability in a mold.

[0005]

According to the present invention, there is provided (a) a methylene bond bonded to a phenol nucleus, wherein a ratio of an ortho bond to a para bond (O / P ratio) is 1.5 to 2.5; The novolak type phenolic resin A having a number average molecular weight of 350 to 600, and (b) the ratio of the ortho bond to the para bond in the methylene bond bonded to the phenol nucleus is 0.7 to 1.
0, and contains novolak-type phenolic resin B having a number average molecular weight of 700 to 1000, (c) hexamethylenetetramine, and (d) a filler, and preferably contains a phenolic resin. The ratio relates to a phenolic resin molding material characterized in that 10 to 45 parts by weight of phenolic resin A is blended with respect to 100 parts by weight of phenolic resin B.

[0006] The novolak type phenol resin used for the molding material generally has a molecular weight of 700 to 1,000. However, by making the molecular weight relatively small, 350 to 600, the thermal stability in the plasticized molten state is improved, and Due to the low viscosity, the fluidity in the mold is good. Molecular weight 35
If it is less than 0, the resin does not easily become solid, and the workability in forming a molding material deteriorates. If it exceeds 600, thermal stability and fluidity will be reduced, which is not preferable.

The novolak type phenolic resin A becomes highly ortho-osmotic with an O / P ratio of 1.5 to 2.5, thereby increasing the activation energy of the resin and improving the curability in the mold. When the O / P ratio is less than 1.5, the curability in the mold becomes insufficient, and it is difficult to produce a resin exceeding 2.5. When the ratio of the phenolic resin A to the phenolic resin B is less than 10 parts by weight with respect to 100 parts by weight of the phenolic resin B, the curability is significantly reduced. Further, when the phenolic resin A is added in an amount exceeding 45 parts by weight, the curability is improved, but the thermal stability is lowered, which is not preferable. As (c) hexamethylenetetramine of the present invention, a powdery substance used as a usual curing agent for phenol resin is used, and usually 7 to 30 parts by weight, preferably 12 to 20 parts by weight, based on 100 parts by weight of phenol resin. Parts used.

As the filler (e) used in the phenolic resin molding material of the present invention, organic materials such as wood powder, pulp powder, various crushed fabrics, phenolic resin laminates and crushed molded products, silica, Alumina, aluminum hydroxide, glass, talc, clay, mica, calcium carbonate, inorganic powders such as carbon, glass fiber,
One or more kinds of inorganic fibers such as carbon fibers can be used. The mixing ratio in the phenolic resin molding material of the present invention is such that the resin component is 20 to 70% by weight and the filler is 80% by weight.
３０30% by weight.

Further, various additives such as a lubricant, a colorant, a curing accelerator, a flame retardant and the like can be appropriately added to the phenolic resin molding material of the present invention. The phenolic resin molding material of the present invention can be produced by blending a resin component, a filler, and other additives, kneading with a roll mill, a twin-screw kneader or the like, and pulverizing as usual.

The phenolic resin molding material of the present invention comprises:
(A) In a methylene bond bonded to a phenol nucleus,
The ratio of ortho bonds to para bonds (O / P ratio) is 1.5-2.
Novolak type phenolic resin A having a number average molecular weight of 350 to 600 and (b) a methylene bond bonded to a phenol nucleus has a ratio of ortho bonds to para bonds of 0.7 to 1.0, and Number average molecular weight is 700-1
Phenolic resin B, (c) hexamethylenetetramine, and (d) a filler. Further, the mixing ratio of the phenolic resin is such that 1 part by weight of the phenolic resin A is added to 100 parts by weight of the phenolic resin B.
It is characterized by being added in an amount of 0 to 45 parts by weight. Such a phenolic resin molding material has remarkably excellent thermal stability in a plasticized molten state at 80 to 120 ° C.,
Excellent curability in a mold at 0 ° C. From this,
The injection molding of the phenolic resin molding material of the present invention can provide a molded article having good characteristics by continuous molding.

[0011]

The present invention will be described below with reference to examples. Table 1
The phenolic resin molding material was obtained by kneading with a heating roll at the mixing ratios of the resin and the filler as shown in (1). Using these, the melt viscosity was measured, injection molding was further performed, the thermal stability and curability in the cylinder were measured, and the strength characteristics of the molded product were evaluated. Table 1 shows the results.

(Evaluation method) Melt viscosity: Shimadzu flow tester (CFT, Shimadzu Corporation)
-500C). 2. In-cylinder stability: Using a family mold (approximately 150 g / 1 shot) including 50 mm x 3 mm, continuously mold 20 shots with an injection molding machine (cylinder temperature 90
C. and a mold temperature of 175.degree. C.). When molding was performed by changing the standing time, the longest standing time at which the molten molding material could flow and sufficiently fill the mold was determined. 3. Curability: After filling with an injection molding machine using the same mold as described above, a molded product of 50φ × 3 mm was taken out after 30 seconds of curing, and the Bacoal hardness after a lapse of 10 seconds was shown.

[0013]

[Table 1]

[0014]

As is clear from the above examples, the phenolic resin molding material of the present invention has excellent fluidity and thermal stability in the molten state and excellent curability at high temperatures. Extremely excellent moldability. Further, a phenolic resin molding material having a melt viscosity at 100 ° C. of 10 ³ Pa · s or less as in the present invention is generally used for injection molding of a thermoplastic resin molding material. Injection molding can also be performed using an injection molding machine having a screw provided with a backflow prevention ring.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08G 14/073 C08G 14/073

Claims (2)

[Claims] 1. A ratio of an ortho bond to a para bond (O / P ratio) in a methylene bond bonded to a phenol nucleus.
Is 1.5 to 2.5, and the number average molecular weight is 350 to
Novolak-type phenolic resin A having a ratio of ortho-bond to para-bond of 0.7 to 1.0 and a number-average molecular weight of 700 to 1000 in a methylene bond bonded to a phenol nucleus. A phenolic resin molding material comprising: resin B; (c) hexamethylenetetramine; and (d) a filler. 2. The mixing ratio of the phenolic resin is such that the phenolic resin A is added to the phenolic resin B in an amount of 10 to 100 parts by weight.
The phenolic resin molding material according to claim 1, which is blended in an amount of 45 parts by weight.