JPS5839172B2 - Hatsupou Seikeiyo Netsukaso Seiji Yushisoseibutsu - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermoplastic resin composition for foam molding, in particular an engineering resin that needs to be molded at a high temperature, and a thermoplastic resin composition reinforced with glass fiber, glass particles, carbon fiber, inorganic filler, etc. The present invention relates to a thermoplastic resin composition for foam molding that is effective for producing foamed engineering resins with excellent mechanical properties.

Many thermoplastic resin foam molded products have already been put into practical use, but most of them are foam molded products of general-purpose resins such as polyethylene, polypropylene, and polystyrene.

These foam molded products are produced by mixing a decomposable blowing agent with a thermoplastic resin and generating decomposition gas by heat during molding to obtain a foam molded product, or by infiltrating the thermoplastic resin with a volatile organic solvent and impregnating it during molding. They are manufactured by methods such as vaporizing the organic solvent used to obtain a foam, or mechanically blowing gas into the molten resin during molding to obtain a foamed molded product, but generally a decomposable blowing agent is used. This method is widely used because it has many advantages, such as not requiring a special molding machine for molding, easy handling, and good storage stability.

When using a decomposable blowing agent, care must be taken in how uniformly the blowing agent is mixed into the resin pellets or powder.

If the blowing agent is unevenly dispersed, large voids or uneven foaming may occur in the molded product, resulting in significant deterioration in mechanical properties and other properties. Mix the decomposable blowing agent uniformly with the resin pellets The method is to mix a blowing agent into resin pellets or powder,
This is kneaded in an extruder at a temperature below the decomposition temperature of the blowing agent and above the softening temperature of the resin without decomposing the blowing agent to obtain pellets containing the undecomposed blowing agent. There is a method of producing a masterbatch by producing pellets with a high concentration of and mixing an appropriate amount with the same or different resin as the base resin of the masterbatch (for example, the method of JP-A No. 47-34856). Both momme methods are difficult to control temperature and there are limits to the selection of blowing agents, so they are not used very often. Various problems also occur.

In particular, the above method is inappropriate for engineering resins that require high performance properties.

Based on the above, generally when using a degradable foaming agent, resin pellets or powder are mixed in a tri-blend, mixed and dispersed in a molding machine such as an injection molding machine or an extrusion molding machine to produce a foamed molded product. A tri-blend method is used to obtain

However, with this method, the foaming agent hardly adheres to the resin pellets, so the foaming agent falls off and the concentration of the foaming agent changes locally, resulting in uneven foaming and even large voids. It is difficult to obtain a foam molded product that is uniformly foamed and has excellent mechanical properties.

In order to improve these drawbacks of the triblend method, the surface of the resin pellets is conventionally moistened with a wetting agent such as mineral oil, polyethylene glycol, dioctyl phthalate, or metal stearate, and then this mixture is A method used to prevent the foaming agent from falling off was to mix a degradable blowing agent with a cone blender, etc., but in order to completely prevent the blowing agent from falling off, it was necessary to completely moisten the surface of the resin pellet. However, adding a large amount of wetting agent may reduce the mechanical properties, cause the wetting agent to bleed onto the surface of the molded product, or even cause bridging of the resin pellets in the hopper of the molding machine. In particular, thermoplastic resin pellets reinforced with glass fibers, glass particles, carbon fibers, inorganic fillers, etc. are more difficult to mold than non-reinforced resins due to the many irregularities on the pellet surface. Since the pellets have a large surface area, it is necessary to add a larger amount of wetting agent, and these problems are particularly serious.

The present inventors have conducted various studies in order to completely adhere the blowing agent to the surface of the resin pellet or powder by adding a small amount of wetting agent, and to obtain a triblend composition in which the blowing agent does not fall off. It was discovered that all of these problems could be solved by using a blowing agent, and this led to the present invention.

That is, the present invention provides 1,5-phenyltetrazole (I) based on 100 parts by weight of a thermoplastic resin (T) that can be molded at a temperature of 240° C. or higher, and a thermoplastic resin that is liquid at room temperature and that can be molded into the thermoplastic resin. Wetting agent (1
) (however, l) per 100 parts by weight,
(1) Ratio of 5 to 20 parts by weight) This relates to a thermoplastic resin composition for foam molding consisting of 0.1 to 5.0 parts by weight.

The thermoplastic resin (I) that can be used in the present invention may be any thermoplastic resin as long as it can be molded at 240°C or higher, and general-purpose resins such as polyethylene and polypropylene can of course be used, but in particular, nylon 6, which needs to be molded at high temperatures, nylon 66
It is effective when using engineering resins such as polycarbonate, saturated polyester, etc.

Furthermore, it is also suitable for those resins reinforced with glass fibers, glass particles, carbon fibers, inorganic fillers, etc.

The shape of these resins is not limited, and may be either pellet-like or powder-like.

Furthermore, the effects of the present invention are not affected by the unevenness of the resin surface.

Furthermore, the wetting agent (II) of the present invention is liquid at room temperature and (
It has a boiling point higher than the molding temperature of I), and in particular,
Wetting agents with affinity for 5-phenyltetrazole (II) are preferred.

Examples of wetting agents include mineral oil, dioctyl phthalate, polyethylene glycol, and polyethylene glycol is a particularly preferred wetting agent.

The present invention is characterized in that 5-phenyltetrazole is selected as the blowing agent.

That is, by mixing a mixture of 5-phenyltetrazole and a wetting agent into the thermoplastic resin (1), (I)
The result is a composition in which the mixture is uniformly adhered to the surface of the substrate.

Therefore, a foam that is uniformly foamed and has no voids can be obtained.

Furthermore, since a small amount of wetting agent is sufficient, a good foamed molded article with little deterioration in the physical properties of the thermoplastic resin can be obtained.

Furthermore, even though the amount of wetting agent is small, a composition with very little foaming agent falling off during transportation can be obtained.

General powder blowing agents other than 5-phenyltetrazole,
For example, when using lyhydrazinotramine, barium azodicarboxylate, etc., the wetting agent, which is liquid at room temperature, will cause primary aggregation when mixed, and the mixture will be uniformly dispersed on the surface of the thermoplastic resin. , it is difficult to obtain a sticky composition.

The amount of each component added in the present invention is 5 to 20 parts by weight of wetting agent (1) per 100 parts by weight of 5-phenyltetrazole.
Parts by weight, preferably 5 to 10 parts by weight of the mixture,
0.1 to 5 per 100 parts by weight of thermoplastic resin (I)
．． It is added in an amount of 0 parts by weight, preferably 0.5 to 2.0 parts by weight.

A method for obtaining the composition of the present invention includes a method in which 5-phenyltetrazole and a wetting agent are mixed in advance, and the mixture is mixed with a thermoplastic resin or a reinforced thermoplastic resin.

As a mixer, a pump blender, a cone blender, etc., which are used in a normal tri-blend, can be used.
By molding with an extrusion molding machine at a temperature of 240° C. or higher, a uniformly foamed foamed product can be obtained.

Furthermore, various additives, pigments, etc. may be added as necessary, as long as they do not impair the effects of the present invention.

Examples of the present invention are shown below.

Example 1 Mineral oil lky for 10 kg of 5-phenyltetrazole
were mixed using a cone blender.

0.1 kg of the mixture and 1 nylon 66 resin pellet
9.9- were mixed in a cone blender, and then molded in a short shot method using an injection molding machine equipped with a valve nozzle.

The molded product is a flat plate with a wall thickness of 10 mm, a width of 80 mm, and a length of 120 mm.There are 2 uniform foam molded products with a skin layer approximately 1 mm thick.
．． Up to 5 times foaming was obtained.

The bending strength of this molded product is approximately 400 kg/c when foamed twice as much.
It was wt.

Example 2 1 kg of polyethylene glycol having an average molecular weight of 400 was mixed with 10 kg of 5-phenyltetrazole in a corn blender.

0.1 kg of the mixture and 19.9 kg of polycarbonate resin pellets reinforced with 20% short glass fibers were mixed in a cone blender, and the mixture was molded using a short shot method in an injection molding machine equipped with a valve nozzle.

The molded product is a rondo with a length of 180 mm and a diameter of 25 mm.The double-foamed molded product is a uniformly foamed molded product with a skin layer about 1 inch thick, and its bending strength is 480 kg/c.
It was trt.

Example 3 1 kg of polyethylene glycol having an average molecular weight of 400 was mixed with 10 kg of 5-phenyltetrazole in a cogon blender.

0.1 kg of the mixture and 19.9 kg of nylon 66 resin pellets reinforced with 33% short glass fibers were mixed in a cone blender and foam-molded in the same manner as in Example 2.

The molded product was a uniformly foamed molded product with a skin layer about 2 times thicker until double foaming, and the physical properties of this molded product are shown in Table 1.

Comparative example 1 100g of trihydrazinotramine and average molecular weight 400
When mixed with 10 g of polyethylene glycol in a polyethylene bag, the trihydrazinotramine powder aggregated, and even when the mixture was mixed with resin pellets, the aggregates of trihydrazinotramine powder separated. It was not possible to disperse it uniformly.

Comparative example 2 33% glass fiber reinforced nylon 66 resin pellets) 10k
Specified amounts of polyethylene glycol having an average molecular weight of 400 were mixed in a cone blender, and 50 g of 5-phenyltetrazole was mixed in the mixture with a cone blender.

5 kg of each of the tri-blend composition button and the composition of Example-3 were taken out, each was placed in a polyethylene bag and vibrated for 5 minutes, and then classified with a 25-mesh sieve to obtain 5-phenyltetrazole. The amount of falling off was measured and was as shown in Table 2.

Further, from the remaining tri-blend composite material, a foamed molded product of approximately 1.5 times the size was molded by the method of Example 3, and
The bending strength of the shot and 5 shots before the completion of molding was measured and the results are shown in Table 2.

If the amount of polyethylene glycol added is small, the blowing agent will fall off and foaming will be sufficient at the start of molding, but before the end of molding, a short shot will occur and a good molded product will not be obtained. When a large amount of polyethylene glycol is added, no shedding occurs, but a decrease in physical properties is observed due to the addition of a large amount of polyethylene glycol.

Claims (1)

[Claims] Thermoplastic resin (I
) A mixture of 17 parts by weight of 5-phenyltetrazole (n)z- and a wetting agent (lI) which is liquid at room temperature and has a boiling point higher than the molding temperature of the thermoplastic resin (
However, for 100 parts by weight of (n), (1) 5 to 2
0 parts by weight) 0.1 to 5.0 parts by weight of a thermoplastic resin composition for foam molding.