JP5170735B2 - Plastic molded product - Google Patents

Description

  The present invention relates to resin molded products such as automobile parts, industrial containers, food containers, and food containers.

For automobile parts, industrial containers, food containers, food containers and the like, resin molded products made of a resin composition mainly composed of polyethylene resin or polypropylene resin are frequently used.
Polyethylene resins and polypropylene resins have a surface hardness of 2B to 4B and are soft and easily scratched.

  Therefore, the surface hardness of the resin molded product is increased by using a resin composition containing an inorganic filler such as talc for molding resin molded products such as automobile parts, industrial containers, food containers and food containers. (See Patent Document 1).

On the other hand, since polyethylene resin and polypropylene resin are oleophilic, they do not easily fall off when an oily substance adheres. Therefore, in the case of a resin molded product made of a resin composition containing a conventional polyethylene resin or polypropylene resin as a main component, there is a problem that black stains become conspicuous over time.
This black dirt is caused by airborne dust such as oil mist and carbon in the exhaust gas, dust in the air (dust dust, clay fines) attracted by the static electricity of the molded product. .

Conventionally, when there is dirt as described above, it looks unclean in a container such as food and cannot be used. In addition, there is a problem that the value of the automobile itself is lowered in the automobile parts.
Therefore, in containers for foods, hot water of 70 ° C to 80 ° C was used and washed frequently to eliminate noticeable dirt. However, when washing, the surface is rubbed with a brush to remove dirt. Even if the surface hardness was increased by the blending of the inorganic filler as described above, the surface was still scratched, and as a result, the scratch was contaminated, and the vicious cycle of washing with a stronger force was repeated.

On the other hand, there is also a method for preventing adhesion of dust or the like to the surface of a resin molded product by blending an antistatic agent in the resin composition.
If an antistatic agent with poor compatibility with the resin is blended, the antistatic agent inside the resin molded product will move to the surface side when the antistatic agent on the surface of the resin molded product disappears due to wiping or washing. Can prevent the adhesion of dirt.

  However, if all of the antistatic agent inside the molded product is consumed, the effect of preventing the adhesion of dust will be lost, so to prevent the adhesion of dirt for a long period of time, a large amount of antistatic agent is added to the resin composition. Although it is necessary to mix | blend, when a lot of antistatic agents are mix | blended with a resin composition, the surface of a molded article will become sticky and will have a dirty feeling and discomfort. For this reason, in many molded products, the attached dust accumulates gradually after use for about one year, and the dirt is thick.

JP 2001-288331 A

  In view of the above circumstances, an object of the present invention is to provide a resin molded article that has a good feeling of use, is hardly scratched on the surface, and can stably prevent adhesion of dirt components for a long period of time.

In order to achieve the above object, the resin molded product according to the present invention is a resin molded product having at least a layer comprising a resin composition containing a polyethylene resin or a polypropylene resin as a main component on the surface. It contains 2 to 6 parts by weight of porous silica having an average particle diameter of 3 μm or more and 5 μm or less and 0.1 to 1 part by weight of an antistatic agent with respect to 100 parts by weight of the main component, and has a hardness of pencil hardness HB or more. It is characterized by having.

In the present invention, the porous silica preferably has some particles exposed on the surface of the resin molded product.
That is, by exposing some of the porous silica particles, it is possible to obtain higher surface hardness and to have odor adsorptivity.

  The polyethylene resin or polypropylene resin includes not only homopolymers but also ethylene-propylene copolymers and mixtures thereof. In addition, if the MFR is excessively large, the dispersion of the silica in the resin becomes non-uniform when the resin is melted, and the effect may be reduced. If the MFR is excessively small, the fluidity of the resin is insufficient. Therefore, the effect of the present invention can be sufficiently exhibited when the MFR is about 3 to 30 g / 10 minutes.

  Although it does not specifically limit as a porous silica, A thing with an average particle diameter of 3 micrometers or more and 5 micrometers or less is preferable. If the average particle size is too small, the particles are fine, so that the exposure to the surface is reduced and the effect expression may be reduced. If it is too large, the surface of the molded product may be rough.

  Although it does not specifically limit as an antistatic agent, For example, glycerin fatty acid ester, polyoxyethylene alkylamine, alkyl diethanolamine etc. can be used. In particular, in the case of a glycerin fatty acid ester having excellent compatibility with a polypropylene resin and a polyethylene resin, the effect is excellent.

  The method for producing the resin molded product of the present invention is not particularly limited, but injection molding is common and may be molded with a single resin composition, but the core layer may be formed with other resin composition by sandwich molding. It may be formed or a core material such as a metal plate may be inserted.

  The blending amount of the porous silica and the antistatic agent is not particularly limited, but the ratio of 2 to 6 parts by weight of the porous silica and 0.1 to 1 part by weight of the antistatic agent with respect to 100 parts by weight of the main component. It is preferable that

That is, when the porous silica is less than 2 parts by weight relative to 100 parts by weight of the main component, the surface hardness cannot be sufficiently secured with the porous silica alone, and when it exceeds 6 parts by weight, the effect of addition cannot be expected any more. In addition, physical properties such as bending strength and tensile strength of the obtained molded product may be reduced.
On the other hand, if the antistatic agent is less than 0.1 part by weight relative to 100 parts by weight of the main component, there is a problem in terms of durability of the antifouling effect by the antistatic agent, and if it exceeds 1 part by weight, the porous material is porous. Depending on the amount of silica, the surface of the molded product may become sticky.

  Further, in the resin composition used for the resin molded product according to the present invention, other inorganic fillers, pigments, antioxidants, light stabilizers, and the like, as long as the purpose of the present invention is not impaired. An ultraviolet absorber, a nucleating agent, a flame retardant, a dispersing agent, etc. can be mix | blended.

  As mentioned above, since the resin composition contains porous silica and an antistatic agent and has a hardness equal to or higher than pencil hardness HB, the surface of the resin molded product according to the present invention is hardly damaged. In addition, the antistatic agent is moderately adsorbed on the porous silica, and therefore gradually bleeds out. That is, the bleed-out speed of the antistatic agent can be suppressed, and the antistatic performance can be maintained for a long time. Therefore, the contamination can be prevented for a long time, and the resin molded product can be used in a clean state for a long time. And until now, since the adhered dirt does not come off, the resin molded product that has become industrial waste can be used for a longer period of time because it becomes difficult to get dirty, and industrial waste can be reduced.

  In addition, in order to remove dirt from containers such as food, washing was performed with hot water of 70 ° C to 80 ° C every time the container was used. It can be used effectively and the load on the environment can be reduced.

  Hereinafter, the present invention will be described in detail with reference to specific examples thereof.

(Example 1)
3 parts by weight of porous silica (trade name Leoroseal QS-102 (hydrophilic) made by Tokuyama Co., Ltd.) and 100 parts by weight of an antistatic agent (Kao Corporation) with respect to 100 parts by weight of polypropylene resin (trade name Prime Polypro J-830HV, manufactured by Prime Polymer Co., Ltd.) A food container having a yellow color as shown in FIG. 1 was molded by injection molding using a resin composition containing 0.2 parts by weight of the electro-stopper 12N).

(Example 2)
Instead of 3 parts by weight of porous silica (trade name Leoroseal QS-102 (hydrophilic)) manufactured by Tokuyama Corporation, 5 weights of porous silica (Silo Hovic 100 (hydrophobic) manufactured by Fuji Silysia) was used as the porous silica. A food container shown in FIG. 1 was molded in the same manner as in Example 1 except that the ingredients were mixed.

(Example 3)
A food container shown in FIG. 1 was molded in the same manner as in Example 1 except that the amount of porous silica was 2 parts by weight.

Example 4
A food container shown in FIG. 1 was molded in the same manner as in Example 1 except that the amount of porous silica was 6 parts by weight.

(Example 5)
A food container shown in FIG. 1 was molded in the same manner as in Example 1 except that the blending amount of the antistatic agent was 0.1 parts by weight.

Example 6
A food container shown in FIG. 1 was molded in the same manner as in Example 1 except that the blending amount of the antistatic agent was 1 part by weight.

(Example 7)
A food container shown in FIG. 1 was molded in the same manner as in Example 1 except that the amount of porous silica was 10 parts by weight.

(Example 8)
A food container shown in FIG. 1 was molded in the same manner as in Example 1 except that the blending amount of the antistatic agent was 1.5 parts by weight.

(Comparative Example 1)
A food container shown in FIG. 1 was molded in the same manner as in Example 1 except that the porous silica was not blended.

(Comparative Example 2)
A food container shown in FIG. 1 was molded in the same manner as in Example 1 except that the amount of porous silica was 1 part by weight.

(Comparative Example 3)
The food container shown in FIG. 1 was molded in the same manner as in Example 2 except that the amount of porous silica was 1 part by weight.

(Comparative Example 4)
A food container shown in FIG. 1 was molded in the same manner as in Example 1 except that no antistatic agent was added.

For the food containers obtained in Examples 1 to 8 and Comparative Examples 1 to 4, pencil hardness measurement, antistatic property evaluation, and dirt evaluation on the container surface were carried out by the following methods, and the results are shown in Table 1. And in Table 2.
[Pencil hardness measurement]
It was based on the scratch hardness (pencil method) of JIS K 5600-5-4.
[Chargeability]
The surface specific resistance value of the container surface immediately after molding, after 1 week of molding, after 1 month of molding, and after 3 months of molding was measured using a surface resistivity measuring machine (Surface Resistivity Meter MODEL 475 manufactured by ACI Incorporated).
[Dirt evaluation]
A mixture of 50% by weight of engine oil (10W-30 for 4-cycle engine manufactured by ExxonMobil Corporation) and 50% by weight of carbon powder as a dirty substance (substitute) is applied to the container surface in a thin film form, Store at 60 ° C x 8 hours, 20 ° C x 16 hours under repeated storage conditions of 1 cycle, 1 week after storage, 2 weeks after storage, 3 weeks after storage, 1 month after storage, 2 months after storage After 3 months, the dirt substance was wiped off with a clean cotton cloth, and then ΔE was measured with a “color difference meter”.

  From the above Tables 1 and 2, it can be seen that the resin molded product of the present invention is less likely to be scratched and dirty than the conventional resin molded product.

Example 9
3 parts by weight of porous silica (trade name Mizukasil P73 (hydrophilic) made by Mizusawa Chemical Co., Ltd.) and 100 parts by weight of an antistatic agent (trade name Electro produced by Kao Co., Ltd.) are added to 100 parts by weight of polyethylene resin (trade name Hi-Zex 2208G made by Prime Polymer Co., Ltd.). The dimensions of each part are shown in FIG. 2 by injection sandwich molding using a resin composition for surface layer containing 0.2 parts by weight of stopper 12N) and a polyethylene resin for core layer (trade name Hi-Zex 2208G manufactured by Prime Polymer Co., Ltd.). A bucket with a blue color was molded.

(Example 10)
As a resin composition for the surface layer, 5 parts by weight of (Silo Hovic 100 (hydrophobic) manufactured by Fuji Silysia) and 100 parts by weight of an antistatic agent (Kao Corporation) with respect to 100 parts by weight of polyethylene resin (trade name Hi-Zex 2208G manufactured by Prime Polymer Co., Ltd.) A bucket having a blue color as shown in FIG. 2 was formed in the same manner as in Example 9 except that 0.2 wt part of the product name electro stopper 12N) was used.

(Comparative Example 5)
As the resin composition for the surface layer, one containing 0.2 parts by weight of an antistatic agent (trade name: Electrostopper 12N, manufactured by Kao Corporation) with respect to 100 parts by weight of polyethylene resin (trade name: Hi-Zex 2208G, manufactured by Prime Polymer Co., Ltd.) was used. Except for the above, a bucket having a blue color as shown in FIG.

  For the buckets obtained in Examples 9 and 10 and Comparative Example 5, the pencil hardness measurement, the antistatic property evaluation, and the dirt evaluation on the bucket surface were performed by the methods described above, and the results are shown in Table 3 and Table 4. It was.

  The resin molded product of the present invention can be used for, for example, automobile parts, industrial containers, food containers, food containers and the like.

It is a perspective view which shows the dimension of each part of the container for foodstuffs produced in Examples 1-8 and Comparative Examples 1-4. It is a perspective view which shows the dimension of each part of the bucket produced in Examples 9 and 10 and Comparative Example 5. FIG.

Claims (1)

In a resin molded article having at least a layer formed of a resin composition containing a polyethylene resin or a polypropylene resin as a main component,
The resin composition contains 2 to 6 parts by weight of porous silica having an average particle diameter of 3 μm or more and 5 μm or less and 0.1 to 1 part by weight of an antistatic agent with respect to 100 parts by weight of the main component, and has a pencil hardness of HB A resin molded product having the above hardness.

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