JPH10120868A - Phenol resin molding material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a phenol resin molding material which has a good flowability and thermal stability in a plasticized molten state, is excellent in curability at high temps., is inhibited from viscosity increase in the plasticized molten state in the cylinder of a molding machine during injection molding, quickly cures in a metal mold, and hardly causes flashes to occur since it is injection molded at a low pressure. SOLUTION: This material contains a novolak phenyl resin having an ortho/ para ratio of 1.0-2.5 and a soln. viscosity (50% ethanol soln., Ostwald method, 25 deg.C) of (80-120)×10<-6> m<2> /sec, a monohydric aliph. alcohol, hexamethylenetetramine and a filler. Pref. the alcohol is a 5C or lower monohydric aliph. alcohol boiling at 80-140 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phenolic resin molding material which is excellent in thermal stability and curability, can be molded at low pressure, and can produce a molded product with less burrs.

[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 90 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. As described above, since the phenolic resin has low thermal stability of the molten resin, when the conventional phenolic resin molding material is injection-molded, the thermal stability of the molding material melted in the cylinder of the injection molding machine is inferior. There is a problem that the condition width is extremely narrow.

[0003] Further, a general phenol resin molding material has a relatively high viscosity even in a state where it is plasticized at 90 to 120 ° C in a cylinder, and is injected into a mold at about 160 to 180 ° C in order to cure. Once the viscosity is reduced, the viscosity rapidly increases with curing, and the time during which good fluidity is maintained is short. Therefore, in order to obtain a good molded product, it must be injected at a high pressure in a short time and injected into a mold, and a residual stress occurs in the molded product formed in the mold,
After being removed from the mold, warping and deformation occur in the molded product when stress is diffused in the cooling process, and gaps are easily generated between the molds when injecting resin at high pressure into the mold,
Burrs are inevitable.

Conventionally, in order to solve these problems, there is a case where molding is performed by lowering the melt viscosity of the molding material, that is, by increasing the fluidity and decreasing the injection pressure. Although it can be reduced, the curing cycle becomes slow, so that the molding cycle becomes long, and it is difficult to put it to practical use.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made as a result of various studies in order to solve these problems, and it is an object of the present invention to provide a method for stabilizing heat in a molten state in a cylinder during injection molding. It is an object of the present invention to provide a phenolic resin molding material having excellent curability, low melt viscosity in a plasticized state, and further excellent curability.

[0006]

SUMMARY OF THE INVENTION The present invention provides (a) an ortho-
The para ratio is in the range of 1.0 to 2.5, and the solution viscosity (50
% Ethanol solution, Ostwald method (25 ° C.)
0-120) × 10 ⁻⁶ m ^{2 /} sec novolak-type phenolic resin, (b) monovalent aliphatic alcohols,
A phenolic resin molding material comprising (c) hexamethylenetetramine and (d) a filler.

In the present invention, (a) the ortho-para ratio is in the range of 1.0 to 2.5, and the solution viscosity (50% ethanol solution, Ostwald method (25 ° C.)) is (80 to 12).
0) Novolak-type phenolic resin of ^10-6 m2 ^/ sec, (b) monohydric aliphatic alcohols are quickly melted and reduced in viscosity during depopulation during injection molding, and are thermally stable in a molten state. It is used to provide improved properties, and at high temperatures it cures quickly, making it possible to shorten the molding cycle. The solution viscosity of the conventional novolak resin is (80 to 300) × 10 ⁻⁶ m ^{2 /} sec. With a novolak resin having a solution viscosity of (121 to 300) × 10 ⁻⁶ m ^{2 /} sec, (b) even if a monovalent aliphatic alcohol is added, the viscosity does not become low, and the solution viscosity becomes (80 to 120). × 1
The novolak resin of 0 ^-6 m ^{2 /} sec does not have a low viscosity unless used in combination with (b) a monohydric aliphatic alcohol.

In the present invention, (b) monohydric aliphatic alcohols include primary alcohols such as methanol, ethanol, propyl alcohol, butyl alcohol, amyl alcohol, hexyl alcohol, heptyl alcohol and octyl alcohol; There are secondary alcohols and tertiary alcohols such as isopropyl alcohol and isobutyl alcohol which are isomers of these, and one or more of these can be used. These alcohols have the effect of reducing the viscosity in the molten state at 80 to 120 ° C. when plasticizing and measuring the molding material in the cylinder of the injection molding machine. Furthermore, when the boiling point of these alcohols is close to the above temperature range, the latent heat of evaporation has the effect of reducing the heat generated by the shearing of the molding material from the screw and the cylinder wall, and suppresses the acceleration of the curing of the molding material and the thermal stability. To improve. These alcohols are preferably alcohols having 5 or less carbon atoms and boiling points of 80 to 140 ° C. In the present invention, amyl alcohol is more preferred. These are phenolic resin 10
It is used in an amount of 1 to 20 parts by weight per 0 parts by weight.
If the amount is less than 1 part by weight, the above-mentioned effect is small, and if it is more than 20 parts by weight, it is difficult to measure plasticization by an injection molding machine.

In the present invention, the compounding ratio of (c) hexamethylenetetramine is 7 to 7 with respect to the phenol resin component.
It is 25% by weight, preferably 10 to 20% by weight. If it is less than 7% by weight, curing will not be sufficiently performed, and if it is more than 25% by weight, the curability will not be improved, and conversely the properties of the molded article (for example, mechanical strength) will be reduced.

As the filler (d) used in the phenolic resin molding material of the present invention, organic fillers such as wood powder, pulp powder, pulverized various fabrics, phenolic resin laminates, pulverized molded articles, 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, and a flame retardant can be appropriately blended into the phenolic resin molding material of the present invention.

[0011] The phenolic resin molding material of the present invention comprises a resin component, a filler, and other additives.
It can be manufactured by kneading with a twin-screw kneader or the like and pulverizing.

The phenolic resin molding material of the present invention has an ortho-para ratio of 1.0 to 2.5 as a phenolic resin and a solution viscosity (50% ethanol solution, Ostwald method (25 ° C.)) of (80). ~ 180) × 10 ^-6 m ^{2 /} s
ec, a novolak-type phenol resin is used, and monohydric aliphatic alcohols are further blended. Such a phenolic resin molding material has a melt viscosity at 100 ° C. of 10 ³ Pa · s or less, has a low melting state in a cylinder of an injection molding machine, is excellent in heat stability, and needs to apply extra pressure during injection. In addition, since the mold cavity can be filled with a low pressure, generation of burrs can be significantly suppressed.
Furthermore, since plasticization is possible at a temperature of 70 to 80 ° C. in the cylinder of the injection molding machine, heat generation due to shearing is small, acceleration of the curing reaction can be further suppressed, and thermal stability is dramatically improved. In addition, fluidity and curability are excellent in a mold at 160 to 200 ° C. Therefore, the phenolic resin molding material of the present invention has a wide range of molding conditions and good continuous moldability in injection molding.

[0013]

The present invention will be described below with reference to examples. In the formulations, "parts" are parts by weight. The phenolic resin molding material was obtained by kneading the resin and the compound shown in Table 1 with a heating roll. Using these, melt viscosity was measured and injection molding was performed, and the results of evaluating the in-cylinder stability and curability are also shown in Table 1.

(Measurement method) Melt viscosity: Shimadzu flow tester (CFT, Shimadzu Corporation)
-500C). 2. Thermal stability: Labo Plastomill (C manufactured by Toyo Seiki Seisaku-sho, Ltd.)
(Mold) to measure the time from melting to curing. 3. In-cylinder stability: A test piece of 60φ × 4mm (hereinafter, referred to as a test piece) is continuously molded for 20 shots (cylinder temperature 90 ° C., mold temperature 175 ° C.,
After molding under the same conditions), it is left in a weighed state, and injection is performed after a predetermined time has elapsed. 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. 4. Curability: Change the holding time in the mold after injection molding,
The presence or absence of blisters on the test piece surface was observed. 5. Injection pressure: The minimum injection pressure at which the test piece can be continuously molded without causing defects such as insufficient filling is indicated by the hydraulic gauge value of the injection molding machine. 6. Burr generation: Burrs generated on the test piece were visually determined.

[0015]

[Table 1]

[0016]

As is clear from the above examples, the phenolic resin molding material obtained according to the method of the present invention is excellent in fluidity and heat stability in a molten state and excellent in curability at high temperatures. For this reason, in the injection molding, the rise in the viscosity of the plasticized molten resin is suppressed in the cylinder of the molding machine, and it is rapidly cured in the mold, so that the moldability is excellent. Furthermore, since injection molding can be performed at a low pressure, generation of burrs can be suppressed. In addition, 100 as obtained in the present invention.
A phenol resin molding material having a melt viscosity at 10 ° C. of 10 ³ Pa · s or less is a screw having a compression ratio of 1.5 or more, which is generally used for injection molding of a thermoplastic resin molding material.
Alternatively, injection molding can be performed in an injection molding machine provided with a screw provided with a backflow prevention ring.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08K 3:00 5:05 5: 3495)

Claims (2)

[Claims] (1) An ortho-para ratio of 1.0 to 2.5.
And the solution viscosity (50% ethanol solution, Ostwald method (25 ° C.)) is (80 to 120) × 10 ⁻⁶ m
^{2 /} sec novolak phenolic resin, (b) 1
A phenolic resin molding material comprising a polyhydric aliphatic alcohol, (c) hexamethylenetetramine and (d) a filler. 2. The method according to claim 1, wherein (b) the monohydric aliphatic alcohol has 5 or less carbon atoms and a boiling point of 80 to 140 ° C.
Phenolic resin molding material.