JP6267869B2 - Foam molding - Google Patents

Description

  The present invention relates to a foamed molded article having a low surface resistivity.

  Polyolefin-based foam molded products or polystyrene-based foam molded products are used as packaging materials for electrical products and electronic parts.

  However, polyolefin-based foam molded products and polystyrene-based foam molded products are excellent insulators, but have the property of easily generating static electricity. Therefore, when used for packaging materials such as the above-mentioned electric products and electronic parts, there arises a problem that dust is attached to the packaging material and the packaging material.

As a method of improving such drawbacks,
Patent Document 1 discloses foam molding in which pre-expanded particles of a polyolefin resin using a glycerin ester of a fatty acid having a specific carbon number and an aliphatic alcohol having a specific carbon number are expanded. However, the effect of reducing the surface resistivity was insufficient.

JP 2010-159388

  An object of the present invention is to provide a foamed molded article having a performance with low surface resistivity even in a low humidity state and a method for producing the same.

  The present invention has the following configuration.

1). A foamed molded article, wherein a boron-based compound is present on the surface of the molded article, and the surface resistivity at a humidity of 12% is 1.0 × 10 ¹⁰ Ω or less.

  2). The foamed molded article according to 1), wherein the boron compound has a donor-acceptor structure with an alcohol compound.

3). The foamed molded product according to 1) or 2), wherein the boron-based compound is present in an amount of 5 g / m ² or more relative to the surface area of the foamed molded product.

  4). The foam molded article according to any one of 1) to 3), wherein the density of the foam molded article is 15 g / L to 200 g / L.

  5). The foamed molded product according to any one of 1) to 4), wherein the foamed molded product is obtained by molding pre-foamed resin particles in a mold.

  6). The foam molded article according to any one of 1) to 5), wherein the base resin of the foam is any one of a polystyrene-based resin, a polyolefin-based resin, and a styrene-modified polyolefin-based resin.

  7). The method for producing a foamed molded product according to any one of 1) to 6), wherein a solution of a boron compound is applied to or sprayed on the surface of the foamed molded product.

  The foamed molded product obtained by the present invention is excellent in performance with low surface resistivity in a low humidity state.

  Examples of the base resin of the foamed molded product that can be used in the present invention include polystyrene resins, polyolefin resins, and styrene-modified polyolefin resins. As the foam molded article, foams of these base resin can be used.

  As the polyolefin foam molding, a foam molding using polyethylene or polypropylene as a base resin is preferable.

  There is no restriction | limiting in particular as a polypropylene resin used for a polyolefin-type foaming molding, A polypropylene homopolymer, an ethylene / propylene random copolymer, a butene-1 / propylene random copolymer, an ethylene / butene-1 / propylene random Examples include copolymers, ethylene / propylene block copolymers, butene-1 / propylene block copolymers, propylene-chlorinated vinyl copolymers, propylene / maleic anhydride copolymers, and the like. Among these, an ethylene / propylene random copolymer and an ethylene / butene-1 / propylene random copolymer are preferable because they have good foamability and good moldability.

  Low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, etc. are raised as polyethylene-based foamed molded products. Among these, linear low-density polyethylene is preferable. It is preferable because a good moldability can be obtained.

  As the polystyrene resin used in the polystyrene foam molded article, a polymer obtained by bulk polymerization or suspension polymerization of a styrene monomer can be used, and the molecular weight of polystyrene or the amount of foaming agent depends on the assumed expansion ratio. Can be appropriately controlled. Moreover, you may copolymerize acrylonitrile, (alpha) -methylstyrene, an acrylate ester etc. as needed.

  The styrene-modified polyolefin resin used in the styrene-modified polyolefin-based molded article is obtained by impregnating a polyolefin component with a styrene monomer and polymerizing the polyolefin component. The polyolefin component can be selected from low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, ethylene-vinyl acetate copolymer, etc., impregnation with styrene monomer, polymerization conditions are polyolefin species and styrene monomer It can be selected appropriately depending on the additional method. Moreover, you may copolymerize acrylonitrile, (alpha) -methylstyrene, an acrylate ester etc. as needed.

  The foamed molded article of the present invention is preferably produced by suspension foaming or melt extrusion, pre-foaming the particulate particles using a foaming agent, and performing in-mold molding. By using the particulate pre-expanded particles, the boron-based compound tends to stay in the recesses between the particles of the foam-molded product, so that the surface specific resistance value can be easily lowered.

  Moreover, even if it uses repeatedly, a boron-type compound does not fall out easily and it is easy to maintain performance. In particular, boron-based compounds have an antistatic effect on the periphery at a distance of about several centimeters, so the effect can be exerted without completely covering the surface of the foamed molded article, so pre-expanded particles were used. When a foamed molded product is used, even if the boron compound on the surface of the molded product falls off, there is an advantage that the performance can be exhibited for a long time only with the boron compound remaining in the groove between the particles.

  As the size of each expanded particle, those having a general size can be used. When the size is too large, there is a problem in the filling property into the mold at the time of molding, and it becomes difficult to hold the boron-based compound between the particles on the surface of the molded body.

  Examples of the foaming agent for foaming various base resins include known ones, for example, aliphatic hydrocarbons such as propane, isobutane, normal butane, isopentane, normal pentane, and neopentane, difluoroethane, tetrafluoroethane, and the like. Volatile foaming agents such as hydrofluorocarbons having an ozone depletion coefficient of zero, inorganic gases such as air, nitrogen and carbon dioxide, water, and the like. The foamed particles thus obtained can be filled into a mold, blown with steam or the like, heated and foamed to obtain a foamed molded product.

  The compound used for improving the surface resistivity of the foam surface of the present invention preferably has a donor-acceptor structure of a boron compound and an aliphatic alcohol compound. Having a donor-acceptor structure is preferable because performance is easily exhibited in a low-humidity environment. The structure of the alkyl group as the aliphatic alcohol compound is not particularly limited, but a polyhydric alcohol is preferable in forming a donor-acceptor structure.

  Since the boron-based compound can exhibit its performance by being present on the surface of the molded body, it is preferably present as uniformly as possible. For this purpose, the boron-based compound is preferably dissolved or diluted in a solvent. The solvent used for dissolution or dilution is not particularly limited as long as the boron compound is dissolved or dispersed without affecting the boron compound to be used or the foamed molded product, but alcohol and water are preferable.

  Specifically, methanol, ethanol, isopropanol, and water can be mentioned, but it is preferable to use as an aqueous solution centered on water. The aqueous solution can be applied or sprayed easily and uniformly on the surface of the foamed molded product, which is preferable for efficiently exhibiting performance. Examples of boron compounds that can be used in the present invention include Antista H, Biomicel BN, Biomicel UB-502 (manufactured by Boron Laboratory).

The amount of the boron-based compound on the surface of the foamed molded body is preferably applied or sprayed so as to be 5 g / m ² or more, more preferably 8 g / m or more, particularly 25 g / m ² or more. It is preferable for stably lowering. If it exceeds 100 g / ^{m 2,} since the contamination of the object by the boron compound when used as a cushioning material is likely to occur, 100 g / ^{m 2} or less, still more 80 g / ^{m 2} or less, particularly 60 g / It is preferable to use at m ² or less.

The foamed molded article obtained as described above is excellent in surface resistivity under a low humidity environment, and has a surface resistivity of 1.0 × 10 ¹⁰ Ω or less even in a dry state such as 12% humidity. It becomes 5.0 × 10 ⁹ Ω or less, particularly 1.0 × 10 ⁹ Ω or less, and can be used without degrading the characteristic performance of the surface resistivity.

  Examples and Comparative Examples are given below, but the present invention is not limited thereby. In addition, about measurement evaluation, it implemented as follows.

<Surface specific resistance value>
The foamed molded product was cut into a sample having a size of 100 mm × 100 mm × 10 mm (t), and the surface resistivity was measured on the uncut surface where the boron-based compound was present. After drying for 12 hours in a drying room at 35 ° C., the temperature of the sample was adjusted to 35 ° C. and the relative humidity to 12% by placing it in an LH40-15P type constant temperature and humidity chamber (manufactured by Nagano Science Co., Ltd.) for 24 hours. .

  Using the sample chamber 1270A type RESISTANCE CHAMBER (manufactured by ADECY Co., Ltd.) that had been installed in the thermo-hygrostat, the surface specific resistance value was measured using a digital super resistance measuring instrument (8340A type ULTRA HIGH RESISTANCE METER (manufactured by ADECY Co., Ltd.). Measurement was performed (measurement condition: after neutralizing for 30 seconds, charging was performed at 1000 V for 30 seconds, and measurement was performed).

<Surface charge>
A polyethylene molded bag (OK bag No. 15, Okura Kogyo Co., Ltd.) immediately after the foam molded product cut out in the same manner as the foam molded product used for the measurement of the surface resistivity and taken out of the thermostat is taken out of the thermostatic chamber. The entire surface of the molded body was quickly rubbed back and forth 5 times, and the surface charge amount of the molded body surface within 1 second was measured immediately after that. The measurement was performed using Electrostatic Meter YC-102 (manufactured by As One Co., Ltd.) at a measurement distance of 30 mm (the rubbing treatment and the charge amount measurement were performed in an atmosphere of 23 ° C. and a relative humidity of 50%).

(Example 1)
Polystyrene expandable resin particles (Kanepal "SBS", manufactured by Kaneka Co., Ltd.) are pre-expanded by a conventional method and expanded in a mold to form a polystyrene-based expanded molded product (300 mm x 400 mm x 25 mm) with a molded product density of 20 g / L. (t)) was produced. On the surface to be used for measurement, boron compound solution “Antista H (Boron Laboratories, Boron antistatic agent concentration 1% aqueous solution)” is used for the surface area of the molded body so that the boron compound is 30 g / m ² . Sprayed evenly with a spray. Table 1 shows the results of the surface specific resistance value and the surface charge amount.

(Example 2)
A sample was prepared in the same manner as in Example 1 except that the boron compound was sprayed at 10 g / m ² .

Example 3
Polyethylene foam particles (Eperan “XL38”, manufactured by Kaneka Corporation) were molded by a conventional method to produce a polyethylene foam molded product (300 mm × 400 mm × 25 mm (t)) having a molded product density of 25 g / L. The boron-based compound solution was sprayed by spraying in the same manner as in Example 1 to adjust the boron-based compound amount to 30 g / m ² with respect to the surface of the molded body.

Example 4
Polypolypropylene expanded particles (Eperan “LBS30”, manufactured by Kaneka Corporation) were molded by a conventional method to produce a polypropylene expanded molded product (300 mm × 400 mm × 25 mm (t)) having a molded product density of 30 g / L. The boron-based compound solution was sprayed by spraying in the same manner as in Example 1 to adjust the boron-based compound amount to 30 g / m ² with respect to the surface of the molded body.

(Example 5)
With reference to the examples of JP2009 / 157374, (Eperan “LBS30”, manufactured by Kaneka Co., Ltd.) was molded by a usual method, and a polypropylene-based foam molded product (300 mm × 400 mm × 25 mm (t)) having a molded product density of 30 g / L. ) Was produced. The boron-based compound solution was sprayed by spraying in the same manner as in Example 1 to adjust the boron-based compound amount to 30 g / m ² with respect to the surface of the molded body.

(Comparative Example 1)
A foam-molded article was produced in the same manner as in Example 1 except that no boron-based compound was used.

(Comparative Example 2)
A foam molded article was produced in the same manner as in Example 2 except that no boron-based compound was used.

(Comparative Example 3)
A foam molded article was produced in the same manner as in Example 3 except that no boron-based compound was used.

(Comparative Example 4)
A foam-molded article was produced in the same manner as in Example 4 except that no boron-based compound was used.

(Comparative Example 5)
A sample was prepared in the same manner as in Example 1 except that the boron compound solution was sprayed so that the boron compound was 4 g / m ² .

(Comparative Example 6)
A sample was prepared in the same manner as in Example 1 except that the boron compound solution was sprayed so that the boron compound was ² g / m ² .

(Comparative Example 7)
A surfactant “EC-4 (produced by Kitahiro Chemical Co., Ltd., aqueous solution of hydroxyalkylamine and isopropyl alcohol)” is used in place of the boron compound, and the surface activity is adjusted so that the amount of the molded body surface is 30 g / m ^2. The procedure was the same as Example 1 except that the agent solution was sprayed.

Claims (7)

The base resin is a resin composed of any one of a polystyrene resin, a polyolefin resin, and a styrene modified polyolefin resin,
The boron compound is present on the surface of the molded body in an amount of 5 g / m ² or more and 100 g / m ² or less, and the surface resistivity at a temperature of 35 ° C. and a humidity of 12% is 1.0 × 10 ¹⁰ Ω or less. Foam molded body.   The foamed molded article according to claim 1, wherein the boron compound has a donor-acceptor structure with an alcohol compound. The density of a foaming molding is 15g / L-200g / L, The foaming molding of Claim 1 or 2 characterized by the above-mentioned. The foam-molded article according to any one of claims 1 to 3 , wherein the foam-molded article is obtained by molding pre-foamed resin particles in a mold. The foamed molded product according to any one of claims 1 to 4 , wherein a boron-based compound is present in a recess between particles of the foamed molded product. The foamed molded product according to any one of claims 1 to 5 , which is obtained by applying or spraying an aqueous solution of a boron compound on the surface of the foamed molded product. The method for producing a foamed molded product according to any one of claims 1 to 5 , wherein a solution of a boron compound is applied to or sprayed on the surface of the foamed molded product.