JP2006083320A - Phenol resin molding material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phenol resin molding material having good mechanical strength and excellent in moldability and curing characteristics without impairing properties which a phenol resin has. <P>SOLUTION: The phenol resin molding material comprises a novolac phenol resin and magnesium oxide having 5-30 nm average particle diameter of primary particles. In the phenol resin molding material, the average particle diameter of secondary particles of the magnesium oxide is preferably 50-200 nm and the content of the magnesium oxide is 0.3-5.0 wt.% based on the novolac phenol resin. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a phenol resin molding material.

Phenolic resins have excellent heat resistance, mechanical strength, and dimensional characteristics, and are therefore used in automobiles, industrial machines, home appliances, and the like. However, since the molding reaction is carried out at the time of molding, the molding cycle becomes longer, and the productivity is inferior to the case where a thermoplastic engineering plastic is used, resulting in an increase in the cost of the molded product. In order to compensate for this, conventionally, it has been possible to increase the amount of curing aid used in combination or to impart high curability by using a novolak resin having a high ortho bond ratio to achieve high cycle.
However, these methods have problems that the curing rate becomes extremely fast, the productivity is deteriorated, and the molding condition width becomes very narrow and the molding is cured during the molding. In addition, the particle size of the curing aid is conventionally about 0.3 μm to 100 μm, but when the curing aid of this particle size increases, the probability that the curing aid becomes the starting point of cracks generated in the molded product is increased. There is also a problem that the mechanical strength is increased and the mechanical strength is lowered and the variation is increased. Therefore, a technique capable of solving such a problem and improving the curing characteristics is required.
As a curing aid, it has been disclosed that magnesium oxide and an amine-based curing agent are used in combination with a resol-type phenol resin (see, for example, Patent Document 1), but it is not intended to solve the above problems.

JP 2003-261742 A

  The present invention provides a phenol resin molding material having good mechanical strength and excellent moldability and curing characteristics without impairing the characteristics of the phenol resin.

The phenol resin molding material of the present invention is achieved by the following present inventions (1) to (6).
(1) A phenolic resin molding material comprising a novolac-type phenolic resin and magnesium oxide having an average primary particle size of 5 to 30 nm.
(2) The phenol resin molding material according to (1), wherein the secondary particles of the magnesium oxide have an average particle size of 50 to 200 nm.
(3) The phenol resin molding material according to (1) or (2), wherein a content of the magnesium oxide is 0.3 to 5.0% by weight with respect to the novolac type phenol resin.
(4) The phenolic resin molding material according to any one of (1) to (3), wherein the content of the novolac type phenolic resin is 20 to 50% by weight with respect to the entire molding material.
(5) The phenol resin molding material according to any one of (1) to (4), further comprising an inorganic filler.
(6) Content of the said inorganic filler is a phenol resin molding material as described in (5) which is 45 to 75 weight% with respect to the whole molding material.

  The present invention is a phenolic resin molding material having good mechanical strength and excellent curing characteristics, and can be applied to automobiles, general-purpose machines, home appliances, peripheral devices, and the like.

Hereinafter, the present invention will be described in detail.
The phenol resin molding material of the present invention (hereinafter sometimes referred to as “molding material”) is characterized by containing a novolak type phenol resin and magnesium oxide having an average primary particle size of 5 to 30 nm.

The novolak type phenol resin used in the present invention is not particularly limited, and examples thereof include phenol novolak resin, cresol novolac resin, bisphenol A novolak resin and the like. Among these, phenol novolac resin is preferable in terms of moldability and cost.
Moreover, hexamethylenetetramine is usually used as a curing agent for novolac type phenolic resins. The content of hexamethylenetetramine is preferably 10 to 20 parts by weight with respect to 100 parts by weight of the novolac type phenol resin.
The content of the novolac type phenol resin is not particularly limited, but is preferably 20 to 50% by weight with respect to the entire molding material. More preferably, it is 30 to 45% by weight. When the content of the novolac type phenol resin is less than the lower limit, production of the molding material may be difficult, and the fluidity of the material may be reduced, which may cause a problem that molding becomes difficult. When the upper limit is exceeded, dimensional changes due to molding shrinkage and post-shrinkage increase, and it may be difficult to maintain a predetermined molded product dimension.

  The molding material of the present invention is characterized by using magnesium oxide having an average primary particle size of 5 to 30 nm. Such magnesium oxide particles have a large surface area capable of reacting with the novolac type phenol resin not only in the form of primary particles but also in the form of secondary particles in which they are aggregated. Thereby, while being able to improve sclerosis | hardenability, content can be reduced.

The average particle size of the magnesium oxide secondary particles is not particularly limited, but is preferably 50 to 200 nm.
Thereby, in the molding material of the present invention, the magnesium oxide is such secondary particles due to such fine secondary particles or energy such as stirring, mixing, and kneading imparted to the material mixture when forming the molding material. It is considered that the particles can be present as finer particles by agglomeration and dissociation. These forms of magnesium oxide particles are finer than conventional micron-level particles and have high dispersibility in the molding material, so that the curing reaction with the novolac-type phenolic resin can be performed uniformly with higher accuracy. Uniform curability can be imparted to the cured product.

In the molding material of the present invention, the content of the magnesium oxide is not particularly limited, but is preferably 0.3 to 5.0% by weight with respect to the novolac type phenol resin. More preferably, it is 0.5 to 1.5% by weight.
Usually, when magnesium oxide having a relatively large particle size is used as a curing aid for a novolak type phenol resin, 5.1 to 6.0% by weight is blended with respect to the novolac type phenol resin. Since the molding material having the above average particle diameter is used, the content can be reduced in this way.

Moreover, in the molding material of this invention, an inorganic filler can be used as a filler.
Examples of the inorganic filler include, but are not limited to, glass fiber, clay, calcium carbonate, talc, aluminum hydroxide, magnesium hydroxide, silica, wollastonite, rock wool, mica, and the like. Or it can mix and use 2 or more types.
In the molding material of the present invention, when an inorganic filler is used, the content is not particularly limited, but is preferably 45 to 75% by weight with respect to the entire molding material. Furthermore, 50 to 60% by weight is preferable. If the value falls below the lower limit, dimensional changes due to molding shrinkage and post-shrinkage increase, and it may be difficult to maintain a predetermined molded product size. In addition, when the above upper limit is exceeded, not only the production of the molding material becomes difficult, but also the problem that the molding becomes difficult because the fluidity of the material decreases.

  As a method for producing the molding material of the present invention, a usual method is adopted. For example, it can be obtained by mixing the above-mentioned blend at a predetermined blending ratio, adding a colorant, a curing catalyst, etc., kneading with a heating roll, and pulverizing it into a sheet. At this time, magnesium oxide may be melt-mixed or pulverized and mixed with the phenol resin in advance.

  The molding material of the present invention can be molded by a conventional molding method such as compression molding, transfer molding, injection molding or the like to obtain a molded product.

  Hereinafter, the present invention will be described by way of examples.

Example 1
35% by weight of novolak-type phenol resin, 5% by weight of hexamethylenetetramine, 40% by weight of glass fiber, 15.85% by weight of calcium carbonate, 0.15% by weight of magnesium oxide A, 2% by weight of colorant, and 2% by weight of release agent The blended raw material mixture was kneaded for 3 minutes with a heating roll at 90 ° C., then taken out, pulverized, and pulverized into granules to obtain a molding material.

(Example 2)
A molding material was obtained in the same manner as in Example 1 except that the amount of calcium carbonate was increased to 15.95% by weight and the amount of magnesium oxide A was decreased to 0.05% by weight.

(Comparative Example 1)
Raw material mixture containing 35% by weight of novolak-type phenolic resin, 5% by weight of hexamethylenetetramine, 40% by weight of glass fiber, 14% by weight of calcium carbonate, 2% by weight of magnesium oxide, 2% by weight of colorant, and 2% by weight of release agent Was kneaded for 3 minutes with a heating roll at 90 ° C., then taken out, pulverized and pulverized into granules to obtain a molding material.

(Comparative Example 2)
A molding material was obtained in the same manner as in Comparative Example 1 except that the amount of calcium carbonate was increased to 15.85% by weight and the amount of magnesium oxide B was decreased to 0.15% by weight.

(Comparative Example 3)
A molding material was obtained in the same manner as in Comparative Example 1 except that the amount of calcium carbonate was reduced to 13% by weight and the amount of magnesium oxide B was increased to 3% by weight.

Each compounding ingredient used for an example and a comparative example is as follows.
(1) Novolac type phenolic resin: PR-50716 manufactured by Sumitomo Bakelite Co., Ltd.
(2) Hexamethylenetetramine: Urotropin manufactured by Sumitomo Seika Co., Ltd. (3) Glass fiber: Chopped strand RES manufactured by Nippon Sheet Glass Co., Ltd. (fiber length 1 to 3 mm, fiber diameter 10 to 13 μm)
(4) Calcium carbonate: SS80 manufactured by Nitto Flour Chemical Co.
(5) Magnesium oxide A: manufactured by Hosokawa Micron, average particle size of primary particles 20 nm, average particle size of secondary particles 100 nm
(6) Magnesium oxide B: manufactured by Kamishima Chemical Co., Ltd., average particle size of primary particles 400 nm, average particle size of secondary particles 2 μm
(7) Colorant: Carbon black (8) Release agent: Calcium stearate

Among the properties shown in Table 1, the Barcol hardness was measured by hardening a molded product of φ = 50 × 3 mmt by transfer molding in 15 seconds and 25 seconds, and measuring the hardness after 10 seconds from demolding. The higher the value at this time, the higher the degree of curing.
In-cylinder thermal stability, the material is retained in the cylinder of an injection molding machine heated to 95 ° C at the front and 50 ° C at the rear, and the residence time is changed up to 5 minutes every 30 seconds, and the injection time at that time is measured. did. In addition, when the head was cured without being allowed to stay for 5 minutes, the residence time when the head was cured was recorded.
A test piece for measuring the mechanical strength was produced by transfer molding using the obtained molding material. The molding conditions were a mold temperature of 175 ° C. and a curing time of 3 minutes. The characteristics of each molding material in Table 1 were measured by the following method.
(1) Flexural strength and flexural modulus were measured according to JIS K 6911 “General Thermosetting Plastics Test Method”.
(2) Charpy impact strength was measured according to JIS K 6911 “General Thermosetting Plastics Test Method”.

Examples 1 and 2 are both phenolic resin molding materials of the present invention containing novolac-type phenolic resin and magnesium oxide having an average primary particle diameter of 20 nm, and the average particle diameter of primary particles is 400 nm. Compared with the comparative example 1 which mix | blended magnesium oxide, the molded article which has substantially the same sclerosis | hardenability, heat stability, and mechanical strength with a small compounding was able to be obtained.
In Comparative Example 2, magnesium oxide having an average primary particle diameter of 400 nm was used in the same amount as in Example 1, but a decrease in curability and mechanical strength was observed. In Comparative Example 3, a large amount of magnesium oxide having an average primary particle size of 400 nm was blended to ensure the same curability as in the examples, but the amount of curing aid was excessive. The thermal stability was lowered, and the mechanical strength was lowered due to the large amount of magnesium oxide having such a large particle size.

  The phenolic resin molding material of the present invention exhibits excellent mechanical strength and excellent curability and moldability in a small amount compared to conventional phenolic resin molding materials using magnesium oxide with a large particle size as a curing aid. To do. For this reason, this phenol resin molding material is suitably applied to mechanical parts applications such as automotive parts, general-purpose machine parts, and home appliance parts.

Claims (6)

A phenol resin molding material comprising a novolac type phenol resin and magnesium oxide having an average primary particle size of 5 to 30 nm. The phenol resin molding material according to claim 1, wherein the average particle diameter of the secondary particles of magnesium oxide is 50 to 200 nm. The phenol resin molding material according to claim 1 or 2, wherein a content of the magnesium oxide is 0.3 to 5.0% by weight with respect to the novolac type phenol resin. The phenol resin molding material according to any one of claims 1 to 3, wherein a content of the novolac type phenol resin is 20 to 50% by weight with respect to the entire molding material. Furthermore, the phenol resin molding material in any one of Claims 1-4 which contains an inorganic filler. The phenol resin molding material according to claim 5, wherein the content of the inorganic filler is 45 to 75% by weight with respect to the entire molding material.