JPH09137038A - Phenolic resin molding material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phenolic resin molding material which has excellent stability of the resin-molten state in the cylinder, when it is injected, low melt viscosity in the plasticized state and shows excellent curing behavior. SOLUTION: In this phenol resin molding material containing a resole type phenol resin, a crystalline phenol compound having 2 or more benzene nuclei, hexamethylenetetramine, a low-molecular-weight polyolefin and a filler, the number-average molecular weight of the resole type of the phenol resin is 300-500 and the tow-molecular polyolefin is a polyethylene with a molecular weight of 500-1,500.

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 thermal stability and curability and which can be molded at low pressure to obtain 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 characteristics, mechanical characteristics, dimensional stability, etc. and are used in a wide range of fields including electric parts. Generally, these are molded by injection molding,
In the molten state plasticized in the cylinder of the injection molding machine at 90 to 120 ° C., the viscosity of the molten resin increases and the fluidity is lost due to the progress of the curing reaction of the resin, and the thermal stability of the molten resin is low. Become. Therefore, when a conventional phenol resin molding material is injection molded, there is a problem that the molding material melted in the cylinder of the injection molding machine has poor thermal stability and the appropriate condition range is extremely narrow.

Further, a general phenol resin molding material has a relatively high viscosity even in a plasticized state in a cylinder at 90 to 120 ° C., and is cured at the stage of being injected into a mold at 160 to 180 ° C. for curing. With this, the viscosity rises sharply, and the fluidity is maintained for a short time. Therefore, in order to obtain a good molded product, it has to be injected at high pressure in a short time and injected into the mold, and residual stress occurs in the molded product shaped in the mold, and After the product is taken out, warpage or deformation may occur in the molded product when stress diffuses in the cooling process, and a gap may easily occur between the molds when injecting resin at a high pressure into the molds, and burrs are avoided. I can't.

Conventionally, in order to solve these problems, the melt viscosity of the molding material, that is, the fluidity is increased and the injection pressure is decreased to perform molding, but the occurrence of burrs is reduced. Although it is possible, since the curing is slow, the molding cycle becomes long and it is difficult to put it into practical use.

[0005]

The present invention has been made as a result of various studies in order to solve these problems. The purpose of the present invention is to improve the thermal stability of the molten state in the cylinder during injection molding. Another object of the present invention is to provide a phenol resin molding material which is excellent, has a low melt viscosity in a plasticized state, and is excellent in curability.

[0006]

Means for Solving the Problems The present invention comprises (a) a resole type phenolic resin, (b) a crystalline phenol compound having two or more nuclei, (c) hexamethylenetetramine, and (d).
The present invention relates to a phenolic resin molding material containing a low molecular weight polyolefin compound and (e) a filler.

In the present invention, the (a) resole type phenolic resin has a relatively low number average molecular weight of 300 to 500, whereby the thermal stability in the molten state is improved and the melt viscosity is low, so that This results in good fluidity. The number average molecular weight may be 300 or less, but the resin does not easily solidify and the workability in the production of the molding material deteriorates. Further, when the number average molecular weight is 500 or more, the thermal stability and the fluidity are low, and the application to the present invention may be difficult.

In the present invention, (b) the crystalline phenol compound having two or more nuclides is a solid at room temperature, has a clear melting point, and becomes a low-viscosity liquid when melted, and a phenol resin such as hexamethylenetetramine. A phenol compound of a binuclear or higher body that is hardened by reacting with the curing agent. As such a crystalline phenol compound having two or more nuclear bodies,
There are bisphenol compounds such as bisphenol A, bisphenol F, bisphenol AD, bisphenol Z, and bisphenol S, and derivatives thereof, biphenol and its derivatives, trinuclear or tetranuclear phenol compounds such as trisphenol AP, and one of these or Two or more kinds can be used. Since the phenolic resin molding material is a solid at room temperature, the crystalline phenolic compound having two or more nuclear bodies is rapidly melted to have a low viscosity due to plasticization at the time of injection molding, and imparts the property of being molded at a lower pressure than usual. Used for. As the phenol resin, a normal novolac resin can be used, but by using a lower molecular weight novolac resin, the melt viscosity can be further reduced, while the amount of the expensive crystalline phenol compound can be reduced. it can. Bisphenol F and bisphenol A are preferable as the crystalline phenol compound, and bisphenol F is particularly preferable.

In the present invention, the compounding ratio of the (a) resol type phenolic resin and the (b) binuclear or more crystalline phenolic compound can be arbitrarily selected, but preferably (a) / (b) = It is 20/80 to 90/10.
When the amount of the component (b) is small, the above-mentioned characteristics of crystallinity cannot be sufficiently exhibited, and when the amount is large, curing becomes slow. Also,
As the ratio of the component (a) increases, the viscosity of the molten resin increases and the curability is improved, so that it can be appropriately blended within the above range depending on the purpose.

As the hexamethylenetetramine (b) of the present invention, a powdery one used as a curing agent for a usual phenol resin is used, and (b) 100 parts by weight of a crystalline phenol compound having two or more nuclei is used. 7 to 30 parts by weight, preferably 12 to 20 parts by weight.

Examples of the low molecular weight polyolefin compound (c) of the present invention include low molecular weight polypropylene and low molecular weight polyethylene. Such compounds have a molecular weight of from 300 to 30,000. These compounds reduce heat generation due to shearing that is received from the screw and the cylinder wall when plasticizing and measuring the molding material in the cylinder of the injection molding machine, and suppress the progress of curing to improve the thermal stability. It also has the effect of reducing the viscosity in the molten state at 80 to 120 ° C. The molecular weight of these compounds is preferably between 300 and 3000. In the present invention, the one having a markedly reduced viscosity is more preferably a molecular weight of 500.
~ 1500 polyethylene. These compounds are added in an amount of 0.1 to the total amount of the above-mentioned components (a) and (b).
It is used by mixing 10 to 10 parts by weight. When the amount is less than 0.1 part by weight, the above-described action is small, and when the amount is more than 10 parts by weight, the plasticization measurement becomes difficult.

Examples of the filler (d) used in the phenol resin molding material of the present invention include wood powder, pulp powder, various pulverized fabrics, phenol resin laminates, organic substances such as pulverized products, silica, and the like. Alumina, aluminum hydroxide, glass, talc, clay, mica, calcium carbonate, carbon and other inorganic powders, glass fiber,
One or more types of inorganic fibers such as carbon fibers can be used. The blending ratio in the phenol resin molding material of the present invention is 20 to 70% by weight of the resin component containing hexamethylenetetramine and 80 to 30% by weight of the filler.
Further, various additives such as a lubricant, a colorant, a curing accelerator, and a flame retardant can be appropriately added to the phenol resin molding material of the present invention.

The phenol resin molding material of the present invention comprises a resin component, hexamethylenetetramine, a filler, and other additives, which are kneaded with a roll mill, a twin-screw kneader, or the like.
It can be crushed and manufactured.

The phenol resin molding material of the present invention contains a resol type phenol resin having a number average molecular weight of 300 to 500 as a phenol resin and a crystalline phenol compound having two or more nuclei. Therefore, when molding 80-120
In the molten state at ℃, the fluidity is good and the thermal stability is good,
It flows into the mold and a hardening reaction occurs quickly after a certain time,
It gels and hardens. Further, since the low molecular weight polyolefin compound is blended, the melt viscosity is further reduced, and the fluidity and thermal stability are improved. Therefore, by arbitrarily selecting the compounding ratio of the above resin and the compounding ratio of the low molecular weight polyolefin compound, it is possible to obtain a phenol resin molding material having excellent curability and low melt viscosity in a wide range, and high thermal stability. it can. The phenol resin molding material has a melt viscosity at 100 ° C. of 10 ³ Pa · s or less, and further becomes 10 ² or less depending on the ratio of the crystalline phenol compound and the low molecular weight polyolefin compound,
Viscosity in the molten state plasticized in the injection molding machine cylinder is low.

The above-mentioned phenol resin molding material is an example of one having a low melt viscosity and an excellent thermal stability at 90 to 120 ° C., but the phenol resin molding material satisfies the above-mentioned melt viscosity and has a good thermal stability. Of course, it is possible to obtain the excellent moldability that is the object of the present invention.

Therefore, the phenol resin molding material of the present invention melts very quickly in the plasticizing process of the injection molding machine to have a low viscosity and has a good fluidity, so that no extra pressure is applied during injection. Since the mold cavity can be filled with a low pressure, the occurrence of burrs can be 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.

[0019]

EXAMPLES The present invention will be described below with reference to examples. In the formulations, "parts" are parts by weight. The resin and compound shown in Table 1 were kneaded with a heating roll to obtain a phenol resin molding material. 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) 1. 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 × 4 mm (hereinafter referred to as “test piece”) is continuously molded for 20 shots (cylinder temperature 90 ° C., mold temperature 175 ° C., hereinafter, molding is the same) and then left in a weighed state After a certain time, the injection is performed. When molding was performed while changing this standing time, the longest standing time during which the molten material flows and can be sufficiently filled in 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.

[0021]

[Table 1]

[0022]

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 number Agency reference number FI Technical display location C08L 23:00)

Claims (2)

[Claims] 1. (a) Resol type phenolic resin,
In a phenol resin molding material containing (b) a dinuclear or higher crystalline phenol compound, (c) hexamethylenetetramine, (d) a low-molecular-weight polyolefin compound, and (e) a filler, the number average of resol-type phenol resins. A phenol resin molding material having a molecular weight of 300 to 500. 2. The phenol resin molding material according to claim 1, wherein the low molecular weight polyolefin compound (d) is poly (ethylene) having a molecular weight of 500 to 1500.