JPH10278079A - Manufacture of phenol resin high-flow molded body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the manufacturing method of phenol resin high-flow molded body, which is capable of obtaining the uniform phenol resin high-flow molded body, uniform in the degree of curing and reduced in the generation of bubbles or the like, by injection molding. SOLUTION: Upon the injection molding of granular phenol resin molding material, whose grain size is 50 μm or more and whose thermal fluidity, measured through disc cure method, is 60-180 mm while whose surface layer is coated by a low surface tension substance having the melting point of 30-160 deg.C in the composite ratio to phenol resin of 0.1-5 wt %, the molten resin is charged into a mold with the filling speed of 5-30 cm<3> /sec or less and the injection molding is effected under the mold clamping pressure of 70-90 kgf/cm<2> .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a phenol resin high-flow molded article, and more particularly to a method for producing a phenol resin high-flow molded article by injection molding.

[0002]

2. Description of the Related Art Phenol resins are inexpensive and have excellent properties such as heat resistance, rigidity, hardness, electrical insulation and chemical resistance. They have been widely used in various products such as electric materials. Most products use liquid raw materials, which are
The composite thermosetting resin molded article was formed by blending a reinforcing material such as cloth, glass fiber, and inorganic filler, and a filler. Although this molded product is inexpensive, it contains a large amount of unreacted phenol, and inevitably contains air bubbles, and therefore cannot be expected to have a high degree of characteristics, and thus cannot be used for high-performance products.

When a high-purity phenol resin molding material (thermofluid granular molding material) having a solid (powder or granular) thermofluidity at room temperature is used, it has been most commonly used as a phenol resin molding method. In addition to the compression molding method, it can be molded by a transfer molding method, an injection molding method or an extrusion molding method. Here, a method of molding by a transfer molding method, an injection molding method or an extrusion molding method using a thermofluid granular molding material is called high-fluid molding, and the obtained molded body is called a high-fluid molded body.

[0004] Even such a heat-fluidized granular molding material capable of high-fluidity molding is usually used as disclosed in Japanese Patent Publication No. 1-38816, such as a reinforcing material such as glass fiber and a zinc stearate. At present, satisfactory molding cannot be performed unless the composition contains a metal-containing organic lubricant.In other words, when a phenolic resin molding material obtained by removing glass fiber or a metal-containing organic lubricant from such a molding material is subjected to high flow molding, the molding is performed in a cylinder of a molding machine. In addition, the smooth fluidity of the molding material was impaired, and it was difficult to form the material stably and with high precision.

When a phenolic resin molded article is used as a magnetic disk substrate or the like, a phenolic resin molded article that does not include the above-mentioned reinforcing material and has as few impurities as possible is required. Therefore, the present inventors have previously described in Japanese Patent Application No. Hei.
No. 264031 proposed a method of using a phenolic resin molding material that does not contain glass fibers or a metal-containing organic lubricant to obtain a phenolic resin high-flow molded body with high productivity. However, this method has a high generation rate of bubbles serving as defects, and the size of the bubbles is large.

[0006]

SUMMARY OF THE INVENTION In view of the foregoing, an object of the present invention is to provide a phenol resin high-fluidity molded article having a uniform degree of curing and having a small number of air bubbles and the like with good productivity by injection molding. An object of the present invention is to provide a method for producing a resin high-flow molded article.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, a phenol resin molding material in which the surface layer of a specific phenol resin is coated with a low surface tension substance will be described later. It has been found that the above-mentioned problems can be solved by injection molding under the conditions described above, and the present invention has been achieved.

That is, the gist of the present invention is that the particle size is 50 μm.
m or more, the thermal fluidity measured by the disc cure method is 6
When injection molding a phenolic resin molding material comprising a surface layer of a granular phenolic resin having a particle diameter of 0 to 180 mm and a low surface tension substance having a melting point of 30 to 160 ° C coated with a phenolic resin composition ratio of 0.1 to 5% by weight, The filling rate of the molten resin into the mold is 5 to ³⁰ cm ³ / sec, and the mold clamping pressure is 7
This is a method for producing a phenolic resin high-flow molded article, which is injection-molded at a pressure of 0 to 90 kgf / cm ² .

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
In the present invention, a phenol resin molding material obtained by coating a surface layer of a granular phenol resin described below with a low surface tension substance is used. As a granular phenol resin, the particle size is 50
A phenol resin having a thermal fluidity of 60 to 180 mm, preferably 90 to 160 mm measured by a disc cure method is used.
Here, the particle diameter represents the average maximum diameter (circumscribed sphere diameter) of the granular material. When the particle size is less than 50 μm, supply to a molding machine may not be performed stably. The upper limit of the particle size is not particularly limited, but a practical particle size is 100 to 4000 μm.
Is appropriate. The particle shape may be any of a spherical shape, a cylindrical shape, a cubic shape, and the like. When the particle size is small, the spherical shape is more excellent in transportability during molding.

In the present invention, the term "thermofluidity" refers to the property of being solid at normal temperature but showing fluidity when a load is applied in a heated state. However, phenolic resins have self-curing properties differently from ordinary thermoplastic resins, so if heating is continued at a temperature that indicates fluidity for a certain period of time or more, condensation within molecules and / or between molecules will occur. It has the property of starting and crosslinking and curing. Therefore, as a scale representing the heat fluidity, the flow (elongation of diameter; mm) of a sample resin disk under a predetermined load at 160 ° C. measured by JIS standard (disc cure method) described later. The resin having a heat fluidity of less than 60 mm tends to have low moldability,
On the other hand, if the resin exceeds 180 mm, the time required for the curing reaction becomes longer, thereby lowering the productivity. In addition, since water and the like generated by the curing reaction are trapped in the molded product,
There is a risk of defective products.

The method for producing the particulate phenol resin is not limited at all. For example, as described in Japanese Patent Application Laid-Open No. 4-159320, a novolak resin is prepared by adding an alkali catalyst / methylene crosslinking agent such as hexamethylenetetramine and a methylene crosslinking agent. A method of performing suspension polymerization in an aqueous medium in the presence of a turbidity stabilizer (self-curing modified novolak resin method), suspending phenol and formaldehyde in an aqueous medium in the presence of a basic catalyst and a suspension stabilizer A polymerization method (solid resol resin method) such as a method of performing polymerization can be suitably employed. According to these methods, spherical particles having a very high purity and a shape close to a true sphere can be obtained. In order to obtain a molding raw material having a large particle size, a method of granulating the above fine particles to prepare a raw material having a predetermined particle size is effective.

[0012] The low surface tension substance has a melting point of 30 ° C to 160 ° C.
C., preferably 40 ° C. to 80 ° C., a low melting point compound which is solid at room temperature at room temperature, and has a low surface tension substance such as lubricity, mold release and non-adhesiveness (for example, critical surface tension at room temperature [25 ° C.] Is a substance having a characteristic characteristic of about 35 dynes / cm or less), particularly a compound containing no metal element such as metal salts. If the melting point is less than 30 ° C., poor measurement tends to occur during molding, and if it exceeds 160 ° C., lubricity in the cylinder of the molding machine is poor, and stable moldability tends not to be obtained.

Typical examples are higher fatty acids such as lauric acid, palmitic acid and stearic acid; higher fatty acid esters such as lauric acid monoglyceride, ethyl stearate, stearic acid monoglyceride, sorbitan monopalmitate and sorbitan monostearate; Solid fats and oils such as trilaurin, tristearin, hardened castor oil;
Higher fatty acid amides such as stearic acid amide and ethylenebisstearic acid amide; higher aliphatic alcohols such as cetyl alcohol and stearyl alcohol; higher aliphatic (meth) acrylates such as stearyl methacrylate and stearyl acrylate; waxy hydrocarbons such as paraffin wax A polyvalent fluorine-containing higher fatty acid such as perfluorooctanoic acid and 9H-hexadecafluorononanoic acid; a polyvalent fluorine-containing higher aliphatic sulfonamide such as N-ethylperfluorooctylsulfonamide; 2- (perfluorooctyl) Polyvalent fluorine-containing higher aliphatic iodides such as ethyl iodide and 2- (perfluorodecyl) ethyl iodide;
1H, 1H, 9H-hexadecafluorononanol, 2
Poly (fluorinated higher aliphatic alcohols such as-(perfluorooctyl) ethanol and 2- (perfluorodecyl) ethanol; 2- (perfluorodecyl) methyl methacrylate, 1H, 1H, 11H-icosafluoroundecyl acrylate, etc. Poly (fluorine-containing higher aliphatic (meth) acrylates); polyfluoro-containing higher aliphatic hydrocarbons such as perfluorododecane; poly (methyl-oxybenzoate) hexafluoropropene trimer adducts; Polyvalent fluorine-containing aromatic hydrocarbons such as fluorinated aliphatic aromatic compounds and pentafluorobenzamide; polyvalent fluorine-containing oligomer compounds such as TFE wax (tetrafluoroethylene telomer) and CTFE telomer (chlorotrifluoroethylene telomer); Or derivatives thereof,
Low surface tension substances such as a mixture of one or more of these, and a composition in which additives such as a polymerization catalyst are blended with them are exemplified.

The low surface tension substance is added to the surface of the granular phenolic resin particles in an amount of 0.1 to 5% by weight, preferably 0.2 to 3% by weight, based on the phenolic resin. 0.1% by weight of low surface tension substance based on phenol resin
If the amount is less than 5%, the molding may be blocked in the cylinder of the molding machine at the time of molding, and it may be difficult to continuously perform molding. It may be difficult to obtain a transparent molded product.

The coating of the particulate phenolic resin with the low surface tension substance is preferably such that it is distributed as evenly as possible between the particles and the film thickness is uniform. As the coating method, the granular phenolic resin and the low surface tension substance are mixed and mixed at a predetermined temperature within a temperature range from the melting point of the low surface tension substance to the softening point of the granular phenolic resin in a blender with a heating device. A method of stirring, a method of fluid-bed stirring both raw materials at the above temperature, dissolving the low surface tension substance by a solvent showing no solubility in the granular phenolic resin and showing good solubility in the low surface tension substance, A method in which a granular phenol resin is mixed with this solution, and the solvent is distilled off and dried is recommended.

At this time, as described later, it is preferable that the phenol resin molding material is controlled to have a water content of 1% by weight or less at least at the time of molding. Usually, the raw phenolic resin after polymerization contains water of several weight% or more. Therefore, it is effective to dry the phenolic resin before use to reduce the water content within the above-mentioned limits and apply the above coating. is there. As a drying method at this time, a method of heating the granular phenol resin to a temperature of 60 to 120 ° C. in a vacuum or under a circulation of dry air is recommended. In the present method, it is also effective to combine the coating of the phenol resin with the low surface tension substance and the drying of the phenol resin.

In the phenolic resin molding material thus prepared, the coating film is made of a water repellent, low moisture permeable, low surface tension substance. From an industrial viewpoint, it is preferable to store and store in a sealed container or sealed package until immediately before molding in terms of quality control. Of course, even if it is a phenolic resin molding material obtained by coating the granular phenolic resin without drying it as described above, if it is sufficiently dried immediately before molding and molded under conditions that do not absorb moisture, the same molded article as described above can be obtained. Can be made.

At this time, as described above, the phenol resin molding material preferably has a water content of 1% by weight or less, more preferably 0.5% by weight or less.
If the water content exceeds 1% by weight, pores remain in the molded body during molding, and depending on the molding conditions, degradation phenomena such as hydrolysis may occur.

The phenolic resin molding material may contain a cured product of the same type of resin. The molding material containing the cured resin gives a uniform carbon material by firing. Further, when injection molding is performed using the phenolic resin molding material under the molding conditions described below, a phenolic resin molded article substantially free of bubbles and overcured products is obtained.

In injection molding, the molten resin is molded at a filling rate of 5 to 30 cm ³ / sec and a mold clamping pressure of 70 to 90 kgf / cm ² .

The filling speed of the molten resin into the mold is 5 cm ³
If it is less than / sec, the flow of the resin in the mold is slow, so that bubbles are likely to be generated on the outer peripheral portion. 30cm ³ / sec
If the speed is higher, the molten resin may foam due to frictional heat at the nozzle portion, or air bubbles may be generated by entraining air into the resin plate. A more preferable range of the filling rate is 15 to 25 cm ³ / sec.

When the mold clamping pressure is less than 70 kgf / cm ² , bubbles may be generated due to insufficient mold clamping pressure.
If the pressure is higher than 90 kgf / cm ² , a high filling pressure is required, and bubbles may be generated by the molten resin flowing backward in the cylinder. In addition, problems such as dimensional defects and large stress distortion of the product may also occur. A more preferable range of the mold clamping pressure is 75 to 85 kgf / cm.
²

The molded article obtained by the present invention can be used for various purposes as it is,
When curing is performed at a predetermined temperature within a temperature range of 0 ° C., crosslinking proceeds further, and various products having a high degree of curing can be obtained.

However, in the present invention, a phenol resin high-flow molding material is used, the filling rate of the molten resin into the mold is 5 to ³⁰ cm ³ / sec, and the mold clamping pressure is 70 to 90.
By performing injection molding at kgf / cm ² , it becomes possible to mass-produce a uniform phenolic resin high-flow molded body with few defects. Further, by curing the molded body obtained by the present invention at a predetermined temperature, various products having a high degree of curing can be obtained. By baking at high temperature in a gas atmosphere, it becomes a carbon material such as high-purity amorphous carbon (glassy carbon) and high-purity graphite, and can be used for various uses such as a magnetic disk substrate and a crucible container.

[0025]

EXAMPLES Next, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples.

Reference Example Novolak resin (# 600 manufactured by Mitsui Toatsu Chemicals, Inc.) 15
0 parts by weight were melted at 160 ° C. to dissolve 1 part by weight of completely saponified polyvinyl alcohol (degree of polymerization: about 2000).
The mixture was poured into hot water (220 parts by weight) at 0 ° C. with stirring to disperse and form a suspension, and then 24 parts by weight of hexamine was dissolved in 40 parts by weight of warm water and added. The suspension was stirred for 20 minutes to carry out suspension polymerization to terminate the reaction. The suspension was separated into solid and liquid and dried to obtain a granular phenolic resin molding material. Table 1 shows the properties of the phenolic resin molding material.

However, these characteristics shown in Table 1 were measured by the following methods. Thermal fluidity (HPF) is JIS-K-6
911 (1979) 5.3.2 [Molding material (disc type)]
2 g of a sample at 1150 ° C. for 1 minute
It was hot pressed under a load of kg and determined from the diameter (average value of the longest diameter and the shortest diameter) of the formed disk. The average particle size was obtained by developing a sample on a glass plate, taking a micrograph, measuring 100 randomly selected particle sizes, and indicating the average value. The moisture was measured using an infrared heater,
C. for 30 minutes and the weight loss was determined.

[0028]

[Table 1]

Examples 1 to 12 Using the phenolic resin molding materials having the properties shown in Table 1 produced in Reference Examples, and using an M150BL-TS injection molding machine (manufactured by Meiki Seisakusho), the results are shown in Table 2. A disk having a diameter of 260 mm, a thickness of 5.2 mm, and a basis weight of 350 g was formed under the conditions, and the bubble generation rate of the formed product was calculated by the method described below. Bubble generation rate: (the number of molded articles in which bubbles with a diameter of 100 μm or more were generated / the number of shots) × 100

[0030]

[Table 2]

Comparative Examples 1 to 9 Using phenolic resin molding materials having the properties shown in Table 1 produced in Reference Examples, and using an M150BL-TS type injection molding machine (manufactured by Meiki Seisakusho), the results are shown in Table 3. A disk having a diameter of 260 mm, a thickness of 5.2 mm, and a basis weight of 350 g was molded under the conditions, and the bubble generation rate of this molded product was calculated as described above, and the results are shown in Table 3.

[0032]

[Table 3]

It was confirmed that all of the compacts obtained in the present example became high-purity amorphous carbon materials when fired at 1600 ° C. in an inert gas.

[0034]

According to the present invention, it is possible to obtain a high-flowability molded article of a phenolic resin which has almost no defects such as overcured products, has a uniform curing degree, and has no air bubbles. And mass production is possible. In addition, the phenolic resin high-flow molded article obtained by the method of the present invention has a low bubble generation rate, is inexpensive and has heat resistance, rigidity, hardness,
It has excellent properties such as electrical insulation and chemical resistance, and can be suitably used for various applications as products such as optical parts, containers, and window materials. Further, the phenolic resin high-fluidity molded product obtained by the method of the present invention can be made into a high-purity carbon material by firing at a high temperature in a vacuum or an inert atmosphere.
It can be used for various applications such as crucible containers.

Continued on the front page (72) Inventor, Mutsunori Yamao 23 Uji Kozakura, Uji-city, Kyoto, Japan Unitika Central Research Laboratories (72) Inventor Hiroshi Ibuki 23 Uji Kozakura, Uji-city, Kyoto, Japan Unitika Central Research Laboratories

Claims (1)

[Claims] 1. A low surface tension substance having a melting point of 30 to 160 ° C. on a surface layer of a granular phenol resin having a particle diameter of 50 μm or more and a heat fluidity of 60 to 180 mm measured by a disc cure method, based on the phenol resin composition. 0.1-5% by weight
When injection molding the coated phenolic resin molding material, the filling speed of the molten resin into the mold is 5 to 30 cm.
^A method for producing a phenolic resin high flow molded article, wherein injection molding is performed at a pressure of 70/90 kgf / cm ² at ³ / sec.