JPH06192544A - Phenolic resin molding material - Google Patents

Abstract

(57) [Summary] [Structure] A phenol resin molding material containing a phenol resin and an organic filler and an inorganic filler as fillers, the main component of which is a novolac type phenol resin having a number average molecular weight of 800 to 1200. A phenol resin molding material containing natural fiber having a fiber length of 2 mm as an organic filler and one or more selected from talc, clay, aluminum hydroxide, calcium carbonate, and magnesium carbonate as an inorganic filler. [Effect] Mechanical strength at room temperature and at heating is superior to that of conventional molding materials. Furthermore, since it is fast-curing and has no blisters, it does not cause dimensional changes due to blisters, is excellent in dimensional stability, and has good moldability.

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 which is excellent in mechanical strength, particularly in heating, and which is excellent in dimensional stability without blister and dimensional change due to blister.

[0002]

2. Description of the Related Art Conventionally, as means for increasing mechanical strength,
Natural fibers having a long fiber length such as pulp and crushed cloth are blended. When pulp or crushed cloth is blended, the mechanical strength is improved by about 10% compared to before blending. However, since pulp and crushed cloth deteriorate the workability during kneading, make it difficult to flow at the time of molding, and easily cause poor filling,
There is a limit to the blending amount. Further, there is a drawback that the mechanical strength during heating does not improve so much. Further, the mechanical strength is remarkably improved by incorporating glass fiber. However, when glass fibers are used, there is a drawback that abrasion resistance is poor. Further, it is not preferable because it is expensive in terms of cost. Regarding dimensional stability, conventionally, gradual hardening is liable to occur, so that blisters are likely to occur, resulting in deformation due to blisters and dimensional changes.

[0003]

SUMMARY OF THE INVENTION The present invention has been made as a result of various studies in order to solve the above-mentioned problems of the prior art, and its object is to obtain mechanical strength, particularly when heating. It is to provide a phenol resin molding material having excellent mechanical strength and dimensional stability.

[0004]

The present invention is a phenol resin molding material containing a phenol resin and an organic filler and an inorganic filler as fillers, wherein the phenol resin has a number average molecular weight of 800 to 1200. One or more selected from talc, clay, aluminum hydroxide, calcium carbonate, and magnesium carbonate as the inorganic filler, containing novolac-type phenolic resin as the main component, organic fillers containing 0.5-5 mm fiber length natural fibers. It is a phenol resin molding material characterized by containing. The phenol resin used in the present invention has a number average molecular weight of 800 to 1200, preferably 900 to 1100. If the number average molecular weight is 800 or less, improvement in mechanical strength, particularly mechanical strength during heating, cannot be expected. Further, when the number average molecular weight is 1200 or more, the softening point of the phenol resin is high, so that the resin cannot be uniformly kneaded, or the melt viscosity becomes high, resulting in poor fluidity and unfavorable molding. Further, the above-mentioned phenol resin is preferably a novolac type phenol resin in which the ratio of ortho bond to para bond in the methylene bond bonded to the phenol nucleus is 0.6 to 1.2, from the viewpoint of curability and mechanical strength.

The filler is an organic filler having a fiber length of 0.
5-5 mm organic natural fibers are used. Examples of such organic natural fibers include fibers such as cotton and hemp, cut or crushed products of these fabrics, various pulps, and the like, and two or more kinds of different materials can be used in combination. These fibers preferably have a fiber length of 0.1 to 5 mm, more preferably 0.5 to 2 m.
m. If the thickness is 0.1 mm or less, the mechanical strength of the molded product is not improved, and if it is 5 mm or more, the mechanical strength is improved. As the inorganic filler,
One or more selected from talc, clay, aluminum hydroxide, calcium carbonate and magnesium carbonate are used. By using these inorganic fillers, the heat resistance is improved, the reduction in mechanical strength during heating can be reduced, and further, the surface hardness is imparted, and the dimensional change due to blister of the molded product can be eliminated.

The preferred blending amount of these fillers is 10 to 10 parts by weight of the organic resin and 100 parts by weight of the phenol resin.
50 parts by weight and 15 to 40 parts by weight of inorganic filler. When the amount of the organic natural fiber is 10 parts by weight or less, the mechanical strength of the molded product is not improved, and when it is 50 parts by weight or more, the bulkiness of the molding material becomes large, and it becomes difficult to form the molding material. Further, if the amount of the inorganic filler is 15 parts by weight or less, the heat resistance is not improved, and the mechanical strength and surface hardness during heating are reduced. When it is 40 parts by weight or more, the moldability is deteriorated and voids are easily generated on the surface of the molded product, which is not preferable.
With such a combination of fillers, a molding material is obtained which has excellent mechanical strength, especially mechanical strength and dimensional stability during heating, as compared with conventional phenol resin molding materials. If necessary, a curing catalyst, a lubricant, a coloring agent, etc. are added to the phenol resin composition, and the mixture is heated and kneaded to obtain a molding material.

[0007]

The phenol resin molding material of the present invention has a number average molecular weight of 800 to 120 as the main component of the phenol resin.
By using a relatively high molecular weight novolac type phenolic resin having a molecular weight of 0, the cured resin has a long inter-crosslinking chain length and can be imparted with characteristics that are not brittle and have excellent toughness as compared with conventional phenolic resins. Furthermore, the mechanical strength can be further improved by blending an organic natural fiber having a long fiber length. Further, by blending the above-mentioned inorganic filler to impart heat resistance, mechanical strength during heating is improved. Furthermore, the surface hardness is increased by the effect of these inorganic fillers, and the formation of blisters can be suppressed, and a molded product with good dimensional stability can be obtained.

[0008]

EXAMPLES Next, the present invention will be explained based on Examples and Comparative Examples. Here, "part" means "part by weight". The materials and formulations shown in Table 1 were kneaded with a heating roll to obtain a phenol resin molding material.

[Table 1]

Comparative Example 1 is a case where the novolac type phenol resin of Example 1 is replaced with a resin having a number average molecular weight of 800 or less. Comparative Example 2 is a case where the novolac type phenol resin of Example 1 is replaced with a resin having a number average molecular weight of 1200 or more. Comparative Example 3 is a case where the clay of Example 1 is replaced with a crushed cloth and wood flour, and no clay is blended. The molding materials obtained in each of the examples and comparative examples were tested at room temperature (25
C.) and heating (120.degree. C.) flexural strength, Charpy impact strength, and curability (minimum curing time without blistering) were measured. The obtained results are shown in Table 2.

[0010]

[Table 2]

[Measuring method] (1) Bending strength, Charpy impact strength: Measured according to JIS K 6911. (2) Bending strength at 120 ° C .: The atmosphere was kept at 120 ° C. for 30 minutes and then measured at 120 ° C. by the same method as above. (3) Fillability: 180 ° C. with an evaluation mold of 100 × 5 × 2 mm
And injection molding from the length (100 mm) direction (injection pressure 1
250 kgf / cm ² ) and the quality of the filling property was judged. (4) Minimum curing time without blistering: The mold is set to 180 ° C., a test piece of 60φ × 4 mm thickness is molded by injection molding,
Curing time is reduced from 20 seconds by 1 second. The curing time 1 second before the occurrence of blisters is the minimum curing time without blistering. For blister, measure the thickness of the molded product with a micrometer, and bulge when the thickness exceeds the specified thickness by 0.05 mm.

The molding materials obtained in Examples 1 to 3 retain a high bending strength even at room temperature and at the time of heating and have a high impact strength and excellent mechanical strength. Further, it is possible to obtain a molded product which has good moldability, is fast-curing, has no blisters, and does not cause dimensional changes due to blisters. In Comparative Example 1, the moldability is good, but the mechanical strength and curability are poor. Comparative Example 2 has high mechanical strength, but poor filling properties and poor moldability. In Comparative Example 3, the mechanical strength at room temperature is high, but the bending strength at the time of heating is poor, and the moldability and curability are also reduced.

[0013]

As is clear from the above examples, the phenolic resin molding material of the present invention is superior in mechanical strength to the conventional molding material at room temperature and at heating. Furthermore, since it is fast-curing and has no blisters, it does not cause dimensional changes due to blisters, is excellent in dimensional stability, and has good moldability.

Claims (1)

[Claims] 1. A phenol resin molding material containing a phenol resin and an organic filler and an inorganic filler as fillers, wherein the phenol resin has a number average molecular weight of 80.
Main component is 0-1200 novolac type phenolic resin, natural fiber with fiber length 0.5-5mm is contained as organic filler, and inorganic filler is selected from talc, clay, aluminum hydroxide, calcium carbonate, magnesium carbonate. A phenolic resin molding material containing one or more of