JP2001040177A - Phenolic resin molding material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phenolic resin molding material having an excellent mechanical strength at heating and having only a small amt. of burrs. SOLUTION: This phenolic resin molding material comprises, as indispensable components, (a) a high mol.wt. novolak type phenolic resin having a wt. average mol.wt. of >50,000 based on a polystyrene as a control material, (b) hexamethylenetetramine as a curing agent and (c) an org. filler and/or inorg. filler. Based on the whole molding material, it pref. comprises (a) 30-60 wt.% of a high mol.wt. novolak type phenolic resin having a wt. average mol.wt. of >=50,000 based on a polystyrene as a control material, (b) 3-18 wt.% of hexamethylenetetramine as a curing agent and (c) 40-60 wt.% of an org. filler such as wood powder and/or an inorg. filler such as calcium carbonate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a phenolic resin molding material which has excellent mechanical strength when heated and generates less burrs.

[0002]

2. Description of the Related Art Phenolic resins are excellent among thermosetting resins in various points such as heat resistance, mechanical strength, and electrical characteristics, and are used for various applications such as molding materials and laminates. Especially for molding materials, the cost can be significantly reduced by replacing metal parts with phenolic resin molding materials reinforced with glass fiber.Therefore, demand for alternative materials for various metal parts such as the automotive field has increased. Is coming. Each year, phenolic resin molding materials are required to have improved properties.In particular, in the field of core parts such as automobile parts, it is necessary to improve not only the strength at room temperature but also the strength at hot time. .

With respect to the moldability, the molding cycle is shortened, and if there are many portions (called burrs) where the molding material has flowed out of the gate portion or parting portion of the mold during molding, the molding material cost increases, The adhesion to the mold or the like easily causes the molded article to remain in the mold, which may cause deterioration in the characteristics of the molded product, poor appearance, and damage to the mold.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a phenolic resin molding material which can provide a molded article having a higher strength when heated as compared with a conventional phenolic molding material and which generates less burrs during molding. To provide.

[0005]

According to the present invention, there is provided a phenolic resin molding material comprising: (a) a high molecular weight novolak type phenolic resin having a weight average molecular weight of 50,000 or more when polystyrene is used as a reference substance; A phenolic resin molding material characterized by containing hexamethylenetetramine as a curing agent, and (c) an organic filler and / or an inorganic filler as an essential component. Preferably, (a) A high molecular weight novolak type phenol resin having a weight average molecular weight of 50,000 or more based on polystyrene as a reference substance, 30 to 60% by weight;
(B) Hexamethylenetetramine 3 to 18 as a curing agent
It is a phenol resin molding material containing 30% to 60% by weight of an organic filler such as wood flour and / or an inorganic filler such as calcium carbonate.

The high molecular weight novolak type phenol resin (a) used in the present invention is a polycondensate of a trifunctional phenol and formaldehyde, and has a weight average molecular weight of 50,000 or more when polystyrene is used as a reference substance. is there. In order to make the molding material quick-curing, it is preferable that the methylene bond at the ortho-ortho position relative to the phenolic hydroxyl group is 60% or more of all methylene bonds. Furthermore, from the workability at the time of forming a molding material, 50,000-
200,000 are preferred.

In the present invention, a high molecular weight novolak type phenol resin having a weight average molecular weight of 50,000 or more when polystyrene is used as a reference substance is used as the phenol resin, and such a high molecular weight phenol resin is used. This makes it possible to increase the viscosity of the molding material at the time of melting to prevent the occurrence of burrs at the time of molding, and to improve the heat resistance, which is a feature of the high molecular weight phenol resin. The compounding ratio of the high molecular weight novolak type phenol resin is preferably 30 to 60% by weight based on the whole molding material. If it is less than 30% by weight, the fluidity during molding is not sufficient, and molding defects such as blurring tend to occur.
If the amount exceeds 100% by weight, the generation of burrs cannot be sufficiently suppressed. In addition, in addition to the high molecular weight novolak type phenolic resin, a small amount of phenolic resin used for a general phenolic resin molding material, for example, 5% by weight or less based on the whole molding material may be blended. This phenol resin can be used as a novolak phenol resin or a resol phenol resin.

In the present invention, hexamethylenetetramine (b) is used as a curing agent in an amount of 3 to 1 with respect to the whole molding material.
Use 8% by weight. If the amount is less than 3% by weight, the curing will be insufficient, and if the amount exceeds 18% by weight, the curability will not be further improved, and conversely, decomposition gas or the like tends to cause molding failure. The preferred range is 3 to 12% by weight.

Regarding the organic filler and / or the inorganic filler (c) used in the present invention, wood powder, plywood powder,
Thermosetting resin powder, crushed cloth, etc., and inorganic fillers include, but are not limited to, glass fiber, calcium carbonate, talc, aluminum hydroxide, and the like. The compounding ratio is preferably 30 to 60% by weight based on the whole molding material as in the case of a general phenol resin molding material. If it is less than 30% by weight, the proportion of the phenol resin is so large that it is difficult to suppress the generation of burrs,
If the amount is larger, the fluidity at the time of molding is not sufficient, and molding defects such as blurring tend to occur.

[0010]

The present invention will be described below with reference to examples.

EXAMPLE 1 22.0 kg of phenol was placed in a 50 L high-pressure reactor having a heat exchanger, a heating device and a two-stage turbine type stirring blade of the same diameter, heated to 180 ° C., and heated to 0 ° C. with nitrogen gas. .8
After pressurizing to MPa, the formic acid content was previously reduced to 50P by ion exchange resin treatment with a diaphragm type high pressure metering pump.
13.3Kg of 40% formalin reduced to PM to 60
The mixture was added sequentially from the lower part of the reactor over a period of minutes to cause an addition condensation reaction. The temperature and the addition rate of the jacket of the reactor were adjusted so that the reaction temperature during this time was 180 to 200 ° C. After completion of the addition, the temperature was maintained for 5 minutes, and after confirming that self-heating did not occur, a dehydration reaction was performed while returning to normal pressure over 30 minutes via a heat exchanger while heating to further maintain the temperature at 220 to 230 ° C. Was. Thereafter, the pressure was reduced to 1.3 KPa, and unreacted phenol was removed for 30 minutes. The unreacted phenol was taken out on a cooling vat, and a novolak type phenol resin having a weight average molecular weight of 52,000 in terms of polystyrene 20.0%
Kg was obtained.

The novolak-type phenol resin having a weight average molecular weight of 52,000, a filler, hexamethylenetetramine, a curing aid, a lubricant, a coloring agent, and the like are blended in the proportions shown in Table 1, and are melt-kneaded with a heating roll and molded. The material was obtained.

Example 2 20.0 kg of phenol was placed in a reactor, 8.9 kg of 88% paraformaldehyde was used as aldehydes, and this paraformaldehyde was previously mixed with 8.0 kg of phenol to form a suspension. Except that the liquid was supplied from the lower part of the reactor with a plunger-type high-pressure metering pump, unreacted phenol was not removed under reduced pressure, and the reaction temperature was 200 to 220 ° C. 27.0 Kg of a novolak phenol resin having a weight average molecular weight of 102,000 in terms of polystyrene reacted in the same manner as in Example 1 was obtained.

This novolak type phenol resin having a weight average molecular weight of 102,000, a filler, hexamethylenetetramine, a curing aid, a lubricant, a coloring agent, and the like are blended in the proportions shown in Table 1, and are melt-kneaded with a heating roll and molded. The material was obtained.

Comparative Example 1 A novolak-type phenol resin having a weight average molecular weight of 8,000 in terms of polystyrene, a filler, hexamethylenetetramine, a curing aid, a lubricant, a coloring agent, and the like were blended in the proportions shown in Table 1 and heated. To obtain a molding material.

A test piece was formed from the obtained molding material by transfer molding (molding conditions: temperature: 175 ° C., time: 3 minutes), and the bending strength at 25 ° C. and 120 ° C. (JIS K)
6911) was evaluated. The bending strength was measured after the test piece was left at the above temperature for 30 minutes. Further, the occurrence of burrs was measured using the transfer mold shown in FIG. Table 1 shows the results.

[0017]

[Table 1]

[0018]

As is evident from the results obtained by the above Examples and Comparative Examples, the phenolic resin molding material of the present invention is superior in heat strength to conventional phenolic resin molding materials, Since it is a molding material that generates few burrs, it is suitably used for molded articles requiring various heat resistances.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a transfer molding die used when measuring the generation of burrs during molding in an embodiment.

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

[Explanation of symbols]

 1 circular cavity 2 air vent (thickness 100 μm) 3 air vent (thickness 50 μm) 4 air vent (thickness 30 μm) 5 air vent (thickness 10 μm) 6 pot 7 plunger

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J002 AA02X AH00X CC04W DE147 DJ047 DL007 EN046 FA047 FA08X FD01X FD017 FD146

Claims (2)

[Claims] 1. A phenolic resin molding material,
(A) a high molecular weight novolak phenol resin having a weight average molecular weight of 50,000 or more when polystyrene is used as a reference substance, (b) hexamethylenetetramine as a curing agent, and (c) an organic filler and / or an inorganic filler. A phenolic resin molding material, characterized by containing as an essential component. 2. The weight average molecular weight of (a) polystyrene as a reference substance is 50,0 based on the whole molding material.
High molecular weight novolak type phenolic resin 3 having a molecular weight of 00 or more
The phenolic resin molding material according to claim 1, comprising 0 to 60% by weight, (b) 3 to 18% by weight of hexamethylenetetramine as a curing agent, and (c) 30 to 60% by weight of an organic filler and / or an inorganic filler. .