JP2001040176A - 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) a phenolic resin having a wt. average mol.wt. of <50,000 based on a polystyrene as a control material, (c) hexamethylenetetramine as a curing agent and (d) an org. filler and/or inorg. filler. Based on the whole molding material, it pref. comprises (a) 20-45 wt.% of a high mol.wt. novolak resin having a wt. average mol.wt. of >=50,000 based on a polystyrene as a control material, (b) 5-40 wt.% of a phenolic resin having a wt. average mol.wt. of <50,000 based on a polystyrene as a control material, (c) 3-12 wt.% of hexamethylenetetramine as a curing agent and (d) 30-60 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 (hereinafter referred to as "a") having a weight average molecular weight of 50,000 or more when polystyrene is used as a reference substance; Novolak type phenolic resin ”is called“ Novolak resin ”),
(B) a phenol resin having a weight average molecular weight of less than 50,000 based on polystyrene as a reference substance, (c) hexamethylenetetramine as a curing agent, and (d) an organic filler and / or an inorganic filler as essential components. It is a phenolic resin molding material characterized by doing.

Preferably, for the entire molding material,
(A) 20 to 45% by weight of a high molecular weight novolak resin having a weight average molecular weight of 50,000 or more when polystyrene is used as a reference substance, and (b) a weight average molecular weight of less than 50,000 when polystyrene is used as a reference substance. 5 to 40% by weight of a phenolic resin, (c) 3 to 12% by weight of hexamethylenetetramine as a curing agent, and (d) an organic filler such as wood flour and / or an inorganic filler 3 such as calcium carbonate.
It is a phenolic resin molding material containing 0 to 60% by weight.

The high molecular weight novolak 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. 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. Further, from the viewpoint of workability in forming a molding material, the weight average molecular weight is 50,000.
~ 200,000 are preferred.

On the other hand, the phenol resin (b) having a weight-average molecular weight of less than 50,000 based on polystyrene used in the present invention can be used as either a novolak resin or a resol resin, and both can be used in combination. You can also. When a resole resin is used, the blending amount of hexamethylenetetramine is appropriately adjusted to be small. The preferred weight average molecular weight is from 1,500 to 30,000 from the viewpoint of workability in forming a molding material.

In the present invention, a high molecular weight novolak resin (a) having a weight average molecular weight of 50,000 or more when polystyrene is used as a reference substance and a phenol resin (b) having a weight average molecular weight of less than 50,000 are used. By using such phenolic resins having different molecular weights together, it is possible to improve the heat resistance and the burr prevention effect at the time of molding, which are the features of the high molecular weight phenolic resin, without significantly increasing the viscosity of the molding material at the time of melting. it can.

The organic filler and / or the inorganic filler is usually blended in an amount of 30 to 60% by weight based on the whole molding material. Considering the amount of hexamethylenetetramine compounded as a curing agent, the compounding amount of both phenolic resins is preferably (a) 20 to 45% by weight of a high molecular weight novolak resin, and (b) Weight average molecular weight 5
It is 5 to 40% by weight of phenolic resin of less than 10,000. When the former is less than 20% by weight or the latter exceeds 40% by weight, the heat resistance and the effect of preventing the generation of burrs during molding are reduced, and when the former exceeds 45% by weight or the latter is less than 5% by weight, In some cases, the viscosity of the material at the time of melting increases, and the moldability decreases.

In the present invention, generally, hexamethylenetetramine (c) is used as a curing agent in an amount of 3 to 12% by weight based on the whole molding material. If the amount is less than 3% by weight, the curing will be insufficient, and if the amount exceeds 12% by weight, the curability will not be further improved, and conversely, decomposition gas or the like tends to cause molding failure. Regarding the organic filler and / or inorganic filler (d) used in the present invention, the organic filler includes wood powder, plywood powder, thermosetting resin powder, and crushed cloth, and the inorganic filler includes glass fiber. , Calcium carbonate, talc, aluminum hydroxide and the like, but are not limited thereto. 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,
When the proportion of the phenolic resin is large, it is difficult to suppress the generation of burrs, and when it is more than 60% by weight, the fluidity during molding is not sufficient, and molding defects such as blurring tend to occur.

[0012]

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

Examples 1 and 2 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 and heated to 180 ° C. 0.8
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 the unreacted phenol was removed for 30 minutes. The unreacted phenol was taken out on a cooling vat to obtain 20.0 kg of a novolak resin having a weight average molecular weight of 52,000 in terms of polystyrene.

The novolak resin having a weight average molecular weight of 52,000 and a weight average molecular weight of 8.0 in terms of polystyrene were used.
Novolak resin No. 00, hexamethylenetetramine, filler, curing aid, lubricant, colorant, etc. were blended in the proportions shown in Table 1 and melt-kneaded with a biaxial roll to obtain a molding material.

Examples 3 and 4 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, and Except for supplying the turbid liquid from the lower part of the reactor with a plunger-type high-pressure metering pump, not removing unreacted phenol under reduced pressure, and having a reaction temperature of 200 to 220 ° C, all A novolak resin 2 having a weight average molecular weight of 102,000 in terms of polystyrene which was reacted in the same manner as in Example 1
7.0 kg was obtained.

A novolak resin having a weight average molecular weight of 102,000 and a weight average molecular weight of 8,8
000 novolak resin, hexamethylenetetramine,
Fillers, curing aids, lubricants, coloring agents, etc. were blended in the proportions shown in Table 1 and melted and kneaded with a biaxial roll to obtain a molding material.

COMPARATIVE EXAMPLE 1 A novolak resin having a weight average molecular weight of 8,000 in terms of polystyrene, a filler, hexamethylenetetramine, a curing aid, a lubricant, a colorant, and the like were blended in the proportions shown in Table 1 and mixed on a biaxial roll. The mixture was melt-kneaded 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.

[0019]

[Table 1]

[0020]

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 Examples.

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

Continued on the front page F-term (reference) 4J002 AA02Y AH00Y CC03X CC04W CC06W DE147 DE237 DJ047 DL007 EU186 FA047 FD01Y FD017 FD146 GN00

Claims (2)

[Claims] 1. A phenolic resin molding material,
(A) 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; and (b) a phenol resin having a weight average molecular weight of less than 50,000 when polystyrene is used as a reference substance. A phenolic resin molding material comprising (c) hexamethylenetetramine as a curing agent, and (d) an organic filler and / or an inorganic filler as essential components. 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 2 having a molecular weight of 00 or more
0 to 45% by weight, (b) 5 to 40% by weight of a phenol resin having a weight average molecular weight of less than 50,000 based on polystyrene, (c) 3 to 12% by weight of hexamethylenetetramine as a curing agent, and (D) An organic filler and / or an inorganic filler is contained in an amount of 30 to 60% by weight.
The phenolic resin molding material according to the above.