JPS63264311A - Phenol aralkyl resin composition for injection molding - Google Patents

Abstract

PURPOSE:To obtain molding material, which does not impair the curing characteristics after its shaping in a mold by a method wherein either furfural or styrene or both are added to ordinary molding material stocks. CONSTITUTION:The concerned phenol aralkyl resin composition for injection molding is produced by adding either furfural or styrene or both to phenol aralkyl resin, hexamethylene tetramine, filler and a compound agent. The mold filling time of the above-mentioned composition is less than or equal to 15 sec, even when the detention time in a cylinder exceeds 4 min under the conditions that a thermosetting resin injection molder, which is equipped with a standard nozzle of 4.5 mm bore, the mold clamping pressure of which is 45 ton, the front and the rear cylinder temperatures of which are set to be 95 deg.C and the injection pressure of which is set to be 410 kg/cm<2>, and a mold, the capacity of a cavity of which is 42 cm<3> and the temperature of which is set to be 160 deg.C, are employed. In other words, said composition can be injected for molding under the state just mentioned above. As a result, by lowering the injection pressure, the enlargement of the mold projected area, the increase of injection capacity, the reduction of injection energy, the miniaturization of sprue and the like become possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a phenolic aralkyl resin composition for injection molding that has excellent low-pressure moldability. More specifically, the present invention relates to a phenol aralkyl resin composition that has excellent fluidity and thermal stability, and has good heat curability.

[Conventional technology]

- In the injection molding of thermosetting resins, S has sufficient fluidity when heated and thermal stability that does not harden in the mold, and it hardens quickly after being shaped in the mold. Materials with properties that are considered to be contradictory are desired;
Many proposals have been made so far.

Although there are no proposals directly related to phenolic aralkyl resins, measures such as using plasticizers or controlling curing agents and curing accelerators are available to improve hot fluidity and thermal stability of phenolic resin molding materials. However, the problem was that the lotus fraction in the molding material increased, impairing the physical properties and appearance of the molded product, and that a sufficient curing speed in the mold could not be obtained. In addition, as a proposal made in view of these shortcomings, for example, Japanese Patent Application Laid-open No. 18861/1983 proposes a method that uses inorganic salt hydrates and utilizes the temperature dependence of water generation due to their decomposition. 1983-137294 discloses a method of post-adding two or more of a fluidity imparting agent, a phenolic resin, and a curing agent to a normal phenolic resin molding material, but all of these methods are insufficiently effective and are not practical. It has not yet become a reality.

[Problems to be solved]

Generally, injection molding of phenolic resin is performed at a cylinder temperature of 95 to 100°C and a mold temperature of around 160°C. In the cylinder, the material is kneaded by a screw, so the temperature of the material is partially higher than the set temperature. Therefore, the material is required to have characteristics such that the curing reaction is suppressed at around 100°C, that is, about 90 to 100°C, and that the curing reaction is not inhibited at around 160°C. All of the conventional proposals have been insufficiently effective in this respect.

[Means to solve problems]

A resin composition made by adding one or more of furfural and styrene to the raw materials of a normal molding material consisting of a phenol aralkyl resin, hexamethylenetetramine, a filler, and a compounding agent can improve fluidity and thermal stability at high temperatures. It is possible to obtain a molding material that is improved and does not impair curability after being shaped in a mold. In other words, the resin composition according to the present invention can be applied at a temperature of 95° C. at the front and rear cylinders, which has not been used in the evaluation of this type of composition, and at the proposed conventional low-pressure moldable material. Mold clamping pressure of 45 to with a standard nozzle of diameter 4.5 mm, set to an injection pressure of 410 kg/d, which is unprecedented
When measuring the mold filling time using an injection molding machine for thermosetting resins and a mold with a cavity capacity of 42 cd set at 160°C, it was found that even if the cylinder temperature residence time exceeded 4 minutes, the mold was not filled. It has a feature that the mold filling time is 15 seconds or less, that is, injection molding is possible. Further, as shown in the reference example, this composition has a hardenability in a high temperature range of around 160° C. that is equal to or higher than that of conventional materials.

The phenol aralkyl resin used in the present invention is derived from phenols and p-xylylene civalides such as α, α9-dichloro p-xylene, p-xylylene dialkyl ethers such as α, α゛-dimethoxy p-xylene, etc. It is a resin that

In addition, in the present invention, a part of the phenol aralkyl resin can be replaced with a phenol resin derived from phenols and aldehydes.

Fillers used in the present invention include wood flour, talc, silica, clay, wollastonite, sepiolite, calcium carbonate, magnesium oxide, potassium titanate, glass fiber, vinylon fiber, aramid fiber, carbon fiber, graphite,
Those used in ordinary phenolic resin molding materials such as carbon blanks can be used.

The compounding agents used in the present invention include pigments, lubricants, conductivity imparting agents, antioxidants, curing accelerators, synthetic resins such as epoxy resins, and silane coupling agents, which are commonly used in phenolic resin molding materials. Can be used.

In the present invention, the usage ratio of hexamethylenetetramine is 6 parts by weight based on 100 parts by weight of the phenol aralkyl resin.
~15 parts by weight, preferably 8 to 12 parts by weight.

In the present invention, the proportion of furfural and styrene used is 1 part by weight per 100 parts by weight of the phenol aralkyl resin.
-15 parts by weight, preferably 2 to 1011 parts. If it is less than 1 part by weight, the effect of improving fluidity is poor;
If the amount exceeds 1 part by weight, the physical properties and appearance of the molded article will be impaired, which is undesirable.

The resin composition of the present invention can be made into a molding material by the usual method of kneading with a roll, kneader, etc., and pulverizing with a power mill, etc.

(Example) Examples 1 to 4 Injection molding with the composition shown in Table 1 using phenol aralkyl resin (Milex XL-225 manufactured by Mitsui Toatsu Chemical Co., Ltd.) and novolac resin (Novolank 100OHs manufactured by Mitsui Toatsu Chemical Co., Ltd.) Thermosetting resin compositions were obtained. These resin compositions were rolled using a 14-inch roll with a front roll of 90
~100℃, if the filler is mainly inorganic, about 60℃, if the filler is mainly wood flour, about 1
The mixture was kneaded at 30° C. for about 2 minutes. The obtained kneaded sheet was cooled and then ground into a molding material using a power mill equipped with a 6m11 screen.

For these molding materials, using a Toshiba Machine ■ lR45P injection molding machine equipped with a standard nozzle with a diameter of 4°5++ uw, the front and rear cylinder temperatures were set at 95°C and the injection pressure was set at 410 kg/cJ. Mold temperature 166
The residence time in the cylinder at which the mold filling time reached 15 seconds was determined as °C. The mold is a JIS family mold for bending strength, Charpy impact strength and water absorption with a cavity capacity of 42cj. The results are shown in Table 1.

Comparative Examples 1 to 4 Molding materials were obtained in the same manner as in Examples 1 to 4, except that furfural and styrene were not used. An attempt was made to measure the mold filling time, which is an indicator of thermal stability, but the injection pressure was too low, making injection difficult and it was not possible to obtain data sufficient for evaluation.

Comparative Example 5 Using a commercially available phenolic resin molding material (P0001 manufactured by Sumitomo Bakelite ■) as a low-pressure injection molding material, the mold filling time was measured in the same manner as in the example. The results are also listed in Table-1.

Reference Example Examples 1 and 4 were examined for their curability at 160°C using a Koka type flow tester. The measurement conditions are load 3
00Kg, nozzle 11wl1ΦX 10+*m. For comparison, the molding material of Comparative Example 1 and PM-000
The curability of No. 1 was investigated. The results are shown in Figure 1.

Regarding the examples, the physical properties of molded products obtained by low-pressure injection molding at 410 kg/cm3 are also listed in Table 1.

〔Effect of the invention〕

The injection molding material obtained using the resin composition of the present invention has excellent low-pressure moldability, and if necessary, can be molded at an injection pressure of 200 Kg/aJ or lower, which was previously impossible in this field. By lowering the injection pressure, for example, the projected area of the mold can be expanded, the injection capacity can be increased,
This makes it possible to reduce injection energy, reduce molded product residual stress, reduce the cross-sectional area of the mold gate, use film gates and pinpoint gates, and downsize runners and sprues.

In addition, by taking advantage of its excellent thermal stability, it is now possible to devise molding methods.For example, it has become possible to apply molding machines and molding methods used for injection molding of thermoplastic resins, so-called cushion molding, and to form molds without flashing. becomes possible. Further, many effects such as being able to shorten the molding cycle by raising the cylinder temperature can be obtained.

The injection molding material obtained from the resin composition of the present invention is
Not only can it be applied to fields where phenolic resin molding materials have traditionally been used, but it can also be used to replace thermoplastic resin molded products or to create large molded products that were previously considered impossible with phenolic resin, such as by molding without molding or large-capacity molding. It can be applied to a wide range of fields.

In addition, although the injection molding material obtained from the resin composition of the present invention is a material with excellent low-pressure moldability, it is of course possible to apply normal injection molding conditions, such as precision molding that takes advantage of high fluidity. It has many industrially useful benefits, such as shortening the molding cycle by shortening the mold filling time, and improving workability when changing brands or troubleshooting due to its thermal stability even if it remains in the cylinder for a long time. Effects can be obtained.

4. Explanation of drawings FIG. 1 is a diagram showing the relationship between preheating time and outflow amount Q.

Patent applicant: Mitsui Toatsu Chemical Co., Ltd. Figure-1 Preheating time 1 second)

Claims (1)

[Claims] 1. A resin composition in which one or more of furfural and styrene is added to a phenol aralkyl resin, hexamethylenetetramine, a filler, and a compounding material, and the cylinder temperature at the front and rear parts is 95°C and injection Diameter 4.5 with pressure set to 410Kg/cm^2
When measuring the mold filling time using a thermosetting resin injection molding machine with a mold clamping pressure of 45 tons and a mold with a cavity capacity of 42 cm^3 and a temperature set at 160°C, the cylinder A thermosetting resin composition for injection molding whose mold filling time is 15 seconds or less even if the residence time exceeds 4 minutes.