JP2000212389A - Melamine resin molding material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a melamine resin molding material having flexibility, good electrical properties such as tracking resistance and color fastness. SOLUTION: The objective molding material is produced by compounding 100 pts.wt. of a melamine resin with 1-40 pts.wt. of an epoxy resin. The epoxy resin preferably has a structure free from benzene ring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention has excellent flexibility, good electrical properties such as tracking resistance and arc resistance and discoloration resistance, and excellent workability in the production of molding materials. Melamine resin molding material.

[0002]

2. Description of the Related Art Melamine resin molding materials have been used for wiring equipment, electric equipment and the like because of their excellent tracking resistance, electric insulation, coloring property and the like. Conventionally, melamine resins include organic fillers such as pulp, cotton dust, cloth chips, and glass, calcium carbonate, clay, mainly for the purpose of improving molding shrinkage and mechanical properties such as impact strength and bending strength. And an inorganic filler such as mica.

[0003] Melamine resins have a higher number of functional groups than other thermosetting resins, and therefore have a high crosslinking density and are liable to cause rigidity of the resin, and lack flexibility and toughness. It is known that a phenol resin such as a resole resin is added to alleviate the rigidity of the melamine resin in order to compensate for the disadvantages. However, the addition of the phenol resin tends to impair the excellent tracking resistance characteristic of the melamine resin, and the discoloration resistance is also impaired by the discoloration of the phenol resin due to oxidation. It is also well known that, by adding a thermoplastic resin such as polyurethane, polyvinyl butyral, or polyvinyl acetate in place of the phenol resin, the rigidity is reduced and the discoloration resistance is improved. This causes the arc resistance to decrease.

In recent years, due to the enforcement of the PL method (product liability law), the adoption of ISO safety standards, and the like, thermoplastic resin molding materials having low electrical properties such as tracking resistance and arc resistance have been replaced with excellent electrical properties. Although melamine resin molding materials are being reviewed, higher electrical properties such as tracking resistance and arc resistance and good discoloration resistance are required.

[0005]

In view of the above, the present invention has excellent flexibility, good electrical properties such as tracking resistance and arc resistance, and good discoloration resistance. An object of the present invention is to provide a melamine resin molding material excellent in workability at the time.

[0006]

The present invention is a melamine resin molding material characterized in that 1 to 40 parts by weight of an epoxy resin is mixed with 100 parts by weight of a melamine resin. Although the melamine resin used in the present invention is not particularly limited, those having a number average molecular weight of 180 to 400 are easy to resinate, workability during molding material production, workability during molding materialization. It is preferred in terms of.

Although any epoxy resin can be used in the present invention, in order to impart flexibility and maintain and improve the electrical properties such as tracking resistance and arc resistance, the epoxy resin containing no benzene ring is used. Those having high properties are preferred. Examples of such an epoxy resin include butylpropyl diglycidyl ether type epoxy resin. Those having an epoxy equivalent of 100 to 5,000 and a number average molecular weight of 500 to 5,000 are preferred in terms of flexibility and appearance of a molded product.

[0008] The flexibility of the melamine resin molded article depends on the crosslinking density of the melamine resin molding material at the time of curing.
Since the number of functional groups of the melamine resin is as large as 6 per triazine nucleus, the melamine resin component has a high crosslinking density at the time of curing. Since the epoxy resin used in the present invention has a smaller number of functional groups per molecular weight than the melamine resin, the rigidity of the melamine resin is reduced by blending the epoxy resin having a long bond chain. The amount of the epoxy resin is preferably from 1 to 40 parts by weight, more preferably from 5 to 15 parts by weight, per 100 parts by weight of the melamine resin.
If the amount is less than 1 part by weight, the flexibility is not sufficiently improved, and
If the amount exceeds 0 parts by weight, unreacted epoxy resin emerges on the surface of the molded article, resulting in poor appearance and reduced flame resistance.

In the production of a melamine resin molding material, there is a problem that as the degree of polymerization of the melamine resin increases, the viscosity increases and the workability decreases. However, when an epoxy resin is added, flexibility is imparted to the resin and productivity is increased. Is improved.

[0010] The melamine resin used in the present invention may be modified with an epoxy resin, rubber or the like. Further, a part of the melamine resin may be replaced with a urea resin or the like. Also,
Raw materials used together with melamine resin and epoxy resin to produce molding materials include fillers such as glass fiber, crushed cloth, and metal oxides, curing agents, coloring agents, release agents, plasticizers, and metal hydroxides. And flame retardants such as materials.

As a method for producing the melamine resin molding material of the present invention, the melamine resin molding material may be heated and kneaded with a usual mixing roll or a twin-screw extruder, or may be granulated with a high-speed rotary mixer. The molding method for obtaining a molded article using the melamine resin molding material of the present invention can be applied to any of injection molding, transfer molding, compression molding and the like, and is not limited.

[0012]

EXAMPLES The raw materials shown in Table 1 were granulated by a high-speed rotary mixer at a predetermined ratio to produce a melamine resin molding material.
For each of the obtained molding materials, a test piece was molded,
Flexural strength (JIS K 7203), flexural modulus (JIS
K7203), Charpy impact strength (JIS K71)
11), bending deflection (JIS K 7203), arc resistance (JIS K 6911), and tracking resistance (IEC. Pub 112) were measured. The molding of the test piece is performed by transfer molding.
3 minutes.

[0013]

[Table 1] * 1) Melamine resin: degree of methylolation 1.70, number average molecular weight 300 * 2) Butyl propyl diglycidyl ether type epoxy resin: epoxy equivalent 600 to 700, number average molecular weight 17
00 * 3) dimethylene ether type resole resin: dimethylene ether group 50 mol%, methylol group mol 15%, number average molecular weight 750

As in the above examples, when an epoxy resin was used, a melamine resin molding material excellent in electrical properties such as tracking resistance and arc resistance and discoloration resistance could be obtained.

[0015]

The melamine resin molding material of the present invention has good electrical properties such as tracking resistance and arc resistance and discoloration resistance, and can provide a molded article having excellent flexibility. Moreover, since the productivity of the molding material is good, it is suitable as an industrial melamine resin molding material.

Claims (3)

[Claims] 1. A melamine resin molding material comprising 100 parts by weight of a melamine resin and 1 to 40 parts by weight of an epoxy resin. 2. The melamine resin molding material according to claim 1, wherein the epoxy resin has a structure containing no benzene ring. 3. An epoxy resin having an epoxy equivalent of 100 to 100.
The melamine resin molding material according to claim 1 or 2, having a number average molecular weight of from 5,000 to 500,000.