JPH05156123A - Molding material of phenol resin - Google Patents

Abstract

PURPOSE:To obtain the subject molding material which is excellent in flowability, gives a molding with no or little occurrence of flash, and therefore can be widely used as a molding material with good moldability. CONSTITUTION:The objectives molding material of phenol resin consists mainly of a phenolic novolak resin, a polynuclear phenolic compound composed of at least three nuclei, a curing agent, and an organic or inorganic filler.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosetting molding material containing a novolac type phenol resin and a polynuclear phenol compound having 3 or more nuclei as a binder.

[0002]

2. Description of the Related Art A phenolic resin molding material is a typical thermosetting resin molding material. Phenolic resin molding materials have excellent mechanical strength, heat resistance, electrical characteristics, and the like, and are therefore used in a wide range of applications such as mechanical parts, electric parts, and automobile parts.

When molding a phenolic resin molding material,
Since the phenolic resin is a condensation type thermosetting resin, there are the following problems that cannot be found in the usual molding of thermoplastic resins. (1) During curing, after the molding material has melted, the melt viscosity increases and it takes a certain amount of time for it to gel and harden, so avoid burrs from the parting surface of the mold during that time. I can't. (2) Since gas such as ammonia is generated during curing,
Since it is necessary to provide an air vent on the parting surface of the mold, the occurrence of burrs here is particularly large. (3) The viscosity of the molding material increases from melting to gelling,
Since the time is several tens of seconds or more, the molding cycle becomes long. In particular, burrs generated in molded products require a great deal of labor for their removal, which increases the cost of this molded product, and while phenolic resin molding materials have excellent properties, they are a major obstacle to the expansion of demand. It was.

[0004]

Therefore, the present invention has been completed by various studies with the main purpose of reducing the occurrence of burrs during molding. When the molding material is melt-cured, the gel is rapidly formed. It was possible to suppress the generation of burrs.

[0005]

DISCLOSURE OF THE INVENTION The gist of the present invention is a novolac-type phenol resin, a trinuclear or higher polynuclear phenol compound, a curing agent, and a phenol resin molding material containing an organic or inorganic filler as a main component. To do. In the present invention, the novolac type phenol resin is not particularly limited as long as it is used in a usual phenol resin molding material. Examples of the trinuclear or higher polynuclear phenol compound include, but are not limited to, the following compounds. These polynuclear phenolic compounds are
Similar to the novolac type phenolic resin, it undergoes a condensation reaction with a curing agent such as hexamethylenetetramine (hereinafter referred to as hexamine) to cure.

[0006]

[Chemical 1]

The compounding ratio of the novolac type phenolic resin and the polynuclear phenolic compound is not particularly limited, but is usually 95: 5 to 5:95. A preferred mixing ratio is 90:10 to 30:70. If the proportion of the novolac type phenol resin is more than 90%, the effect of compounding the polynuclear phenol compound is small, and if it is less than 30%, it takes time to cure and the molding cycle may become long. A more preferred range is 70 to 30 to 50.
Pair 50. To obtain the molding material of the present invention, a novolac type phenolic resin and a polynuclear phenolic compound, a curing agent and a filler are mixed, and then melted and kneaded by an ordinary method, that is, a roll, an extruder, or a Henschel mixer, and then pulverized. By doing so, a molding material is obtained. But,
When the proportion of the polynuclear phenol compound is high, the melting point is high and it may be difficult to form a molding material.Therefore, by appropriately selecting the type and amount of the polynuclear phenol compound, the melting point of the binder component may be lowered. It becomes easy to make a molding material.

Since the polynuclear phenolic compound is crystalline, the molding material obtained by blending the novolac type phenolic resin with the novolac type phenolic resin is melted by heating during molding and becomes a liquid material having good fluidity. And after a certain period of time a curing reaction occurs quickly,
It gels and hardens. From this, especially when the proportion of polynuclear phenolic compound is high, if a molding material is formed in the same manner as a normal phenolic resin molding material, a low-viscosity fluid state during molding continues for a certain period of time. Can be prevented. On the other hand, when curing is slow and the low-viscosity fluid state continues for a long time during molding, the reaction between the novolac type phenolic resin, polynuclear phenolic compound and the curing agent proceeds when forming the molding material or by heating after forming the molding material. If it is stopped at a stage slightly before the start of the curing reaction, when the molding material is molded, it becomes a low-viscosity liquid substance by heating, and then the curing reaction is promptly started to lead to gelation. Therefore, even if the molding is performed at a low pressure, the filling is completed in a short time, and the burrs can be prevented from being generated by the rapid curing. Further, the molding cycle can be shortened.

On the other hand, when the proportion of the novolac type phenol resin is high, it can be produced in the same manner as a usual phenol resin molding material, but depending on the case, it may be heated at the time of forming the molding material or after forming the molding material. The reaction may proceed.

The filler used in the present invention is an organic substance such as wood powder, pulp powder, various crushed fabrics, crushed thermosetting resin laminates and molded products, silica, alumina, glass, talc, clay. Powders such as calcium carbonate and carbon, and inorganic substances such as glass fiber, carbon fiber and mica are used.

[0010]

EXAMPLES The present invention will be described below with reference to Examples and Comparative Examples. Here, "parts" indicate parts by weight. [Example 1] 22 parts of novolac type phenol resin (number average molecular weight 800, the same in the following examples), trisphenol PA 22 parts, hexamine 7 parts, calcium hydroxide 3
Part, wood powder 32 parts, calcium carbonate 11 parts, and mold release agent 3 parts were mixed, melt-kneaded with a roll, cooled and pulverized to obtain a molding material. [Example 2] 35 parts of novolac type phenol resin, 9 parts of trisphenol PA, 7 parts of hexamine, 3 parts of calcium hydroxide, 32 parts of wood powder, 11 parts of calcium carbonate and 3 parts of release agent were mixed and melted by a roll. The mixture was kneaded, cooled, and then pulverized to obtain a molding material.

[Example 3] 13 parts of novolac type phenol resin, 31 parts of trisphenol PA, and 7 of hexamine
Parts, 3 parts of calcium hydroxide, 32 parts of wood powder, 11 parts of calcium carbonate, 3 parts of release agent are melted and kneaded with a roll, then heated at 150 ° C. for 10 minutes, cooled and pulverized to form a molding material. Got [Comparative Example 1] 44 parts of novolac type phenol resin, 7 parts of hexamine, 3 parts of calcium hydroxide, 32 parts of wood powder, 11 parts of calcium carbonate and 3 parts of release agent are mixed, melt-kneaded by a roll, and after cooling. It was crushed to obtain a molding material.

The fluidity (viscosity measured by a Koka type flow tester) was measured for each of the obtained molding materials. Furthermore, transfer molding was performed under the following conditions, and the presence or absence of burrs was measured. The results are shown in Table 1. (Transfer molding conditions) 20 g of the tabletted molding material was preheated to about 100 ° C. and a transfer molding die having the shape shown in FIG. 1 was used to obtain a gauge pressure of 25 kg / cm ² (50 kg / cm in Example 2 and Comparative Example 1 cm ² ), and the temperature was 200 ° C. for 3 minutes. The presence or absence of burrs was determined by visually observing burrs in the mold air vent.

[0013]

[Table 1]

From Table 1, the molding materials obtained in the respective examples have better fluidity than the conventional phenol resin molding materials of the comparative examples. It can be seen that burrs do not occur or are extremely small during molding.

[0015]

As is clear from the above examples, the phenol resin molding material of the present invention has excellent fluidity and has little or no burrs during molding, so that it can be widely used as a molding material having good moldability. It is available.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a transfer molding die used in an example.

FIG. 2 is a sectional view taken along line AA of FIG.

[Explanation of reference numerals] 1 circular cavity 2 square cavity 3, 4, 5 air vent 6 pot 7 plunger

Claims (2)

[Claims] 1. A phenol resin molding material containing a novolac type phenol resin, a trinuclear or higher polynuclear phenol compound, a curing agent, and an organic or inorganic filler as main components. 2. The phenol resin molding material according to claim 1, wherein the ratio of the novolac type phenol resin and the polynuclear phenol compound having 3 or more nuclei is 90:10 to 30:70.