JP2009226871A - Antistatic thermoplastic resin foamed molding and its production process, molding die for producing antistatic thermoplastic resin foamed molding and molding device for producing antistatic thermoplastic resin foamed molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique which decreases washout of a cationic antistatic agent when a preliminary foamed particle contacts steam and allows a low cost obtaining of a foamed molding excellent in antistatic properties. <P>SOLUTION: The production process of an antistatic thermoplastic resin foamed molding is characterized by performing an in-mold foam molding while setting an opening rate between 0.5-1.0%, wherein the opening rate is the ratio of a vent hole opening area to an area of molding face to which the foamed molding in a molding die contacts; provided that the production process of the foamed molding is performed by; containing a foaming agent in a thermoplastic resin particle, preparing a foaming thermoplastic resin particle which adheres a cationic antistatic agent on at least its particle surface, producing the preliminary foamed particle by heating and foaming the foaming thermoplastic resin particle, thereafter filling the preliminary foamed particle in a cavity of a molding die having the cavity corresponding to a desired molding configuration, heating by pouring steam in the cavity through a vent-hole of the molding die and producing the foamed molding by the in-mold foam molding which inflates and fuses the preliminary foamed particle. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention provides a foamed thermoplastic resin particle in which a foaming agent and a cationic antistatic agent are added to a thermoplastic resin particle to produce foamed foam, and the prefoamed particle is formed into a mold cavity. Antistatic thermoplastic resin that fills inside and heats by flowing water vapor into the cavity through the vent hole of the mold, and expands and fuses the pre-foamed particles to produce a foam molded body Production method of foam molded article, antistatic thermoplastic resin foam molded article obtained by the production method, mold for producing antistatic thermoplastic foam molded article suitable for carrying out this production method (hereinafter, And a molding apparatus for producing an antistatic thermoplastic resin foam molding (hereinafter referred to as a molding apparatus).

  Conventionally, when manufacturing a thermoplastic resin foam molded article such as a polystyrene-based resin by performing in-mold foam molding, regarding the adjustment of the opening ratio of a vent hole for heating by flowing water vapor into a cavity, for example, Patent Document 1 The techniques disclosed in -3 are proposed.

  Patent Document 1 discloses a mold comprising a pair of male mold and female mold used for foam molding of pre-foamed resin particles, and forming a cavity space formed when both molds are clamped A molding die having a large number of steam circulation openings formed on the surface, and the opening ratio of the steam circulation openings formed on the molding surface can be changed on at least one of the molding surfaces. A foam molding die is disclosed in which an aperture ratio adjustment auxiliary plate is detachable.

  Patent Document 2 is a foam molding die for foam molding pre-foamed resin particles in which a large number of openings for vapor circulation are formed on a molding surface that constitutes a cavity space formed when the mold is clamped, A foam molding die is disclosed in which the opening area of all or a part of the steam circulation opening is variable.

Patent Document 3 discloses a container made of a polyolefin-based resin foam obtained by a bead method in-mold method, wherein at least the inner surface or outer surface of the bottom surface of the container has an opening area of a steam inlet hole of 4.5% by area ratio. The molded body obtained by foam molding using the mold having the above-described mold surface, and the obtained compact has a convexity with a minor axis of 1 to 5 mm and a groove width of 1 to 5 mm and a depth of 0.3 mm or more. A foam container characterized by having a recess is disclosed.
JP 2004-202994 A JP 2004-230835 A JP 2006-51979 A

As one application of thermoplastic resin foamed molded products such as polystyrene-based resins, glass substrates for manufacturing liquid crystal display devices and plasma display devices, and plate-like substrates such as semi-finished products in which circuits are formed on the glass substrate are used. There is a substrate transport box made of a thermoplastic resin foam molded body for buffering and holding a plurality of sheets arranged in multiple stages.
The required performance for this substrate transport box includes the mechanical properties of the thermoplastic resin foam moldings that make up the box, such as bending strength, compression resistance, impact resistance (durability against drop test), and surface resistivity. Therefore, it is required that the antistatic characteristics such as those fall within a predetermined range.

  As a means for satisfying such an antistatic property, an antistatic agent is adhered to the surface of the foamable thermoplastic resin particles, and the antistatic property of the thermoplastic resin foam molded product obtained by in-mold foam molding is used. Improvements are made to the properties. Examples of such an antistatic agent include a cationic antistatic agent.

  However, this cationic antistatic agent is water-soluble, and when an antistatic agent is added to expandable thermoplastic resin particles and in-mold foam molding is performed, the pre-expanded particles come into contact with water vapor and adhere to the particle surface. Since the cationic antistatic agent is easily washed away, an excess of the antistatic agent had to be added to obtain reliable antistatic properties, leading to an increase in the cost of the thermoplastic resin foam molding. was there.

  The present invention has been made in view of the above circumstances, and when pre-expanded particles come into contact with water vapor, the flow of the cationic antistatic agent is reduced, and the antistatic thermoplastic foam-molded with excellent antistatic properties at low cost. The purpose is to provide a technique capable of obtaining a body.

In order to achieve the above object, the present invention provides foamable thermoplastic resin particles in which a foaming agent is contained in thermoplastic resin particles and a cationic antistatic agent is attached to at least the particle surface, and the foamable thermoplastic resin is prepared. Resin particles are heated and foamed to produce pre-expanded particles, and then the pre-expanded particles are filled into the cavities of the mold having cavities that match the shape of the desired molded body, and the cavity is formed through the vent holes of the mold. In the method for producing an antistatic thermoplastic resin foam molded article, which is produced by producing a foam molded article by in-mold foam molding in which water vapor is flowed and heated to expand and fuse the pre-expanded particles.
In-mold foam molding is performed by setting the opening ratio, which is the ratio of the opening area of the vent hole to the area of the molding surface in contact with the foam molded body of the molding die, in the range of 0.5% to 1.0%. A method for producing an antistatic thermoplastic foamed molded article is provided.

In the method for producing an antistatic thermoplastic resin foam molded article of the present invention, the cationic antistatic agent is represented by the formula (1).
[(R ¹ ) ₄ N] ⁺ C ₂ H ₅ OSO ₃ ⁻ (1)
(Wherein R ¹ represents an optionally branched alkyl group having 1 to 17 carbon atoms) is preferably one or more selected from the group of compounds represented by:

In the method for producing an antistatic thermoplastic foam-molded article of the present invention, the cationic antistatic agent is an alkyl group having 3 to 3 carbon atoms out of the four R ¹ groups in the formula (1). It is preferable that

In the method for producing an antistatic thermoplastic foam-molded article of the present invention, the cationic antistatic agent is an alkyl group having 3 to 3 carbon atoms out of the four R ¹ groups in the formula (1). It is preferable that the remaining one is an alkyl group having 5 to 17 carbon atoms.

  In the method for producing an antistatic thermoplastic resin foam molded article of the present invention, the vent hole is formed by mounting a lotus root type ventilation member having a large number of small holes formed in a hole formed in the mold. Is preferred.

  The present invention also provides an antistatic thermoplastic resin foam molded article obtained by the above-described method for producing an antistatic thermoplastic resin foam molded article.

Further, the present invention is a molding die used in the above-described method for producing an antistatic thermoplastic resin foam molded article,
Provided is a molding die characterized in that the opening ratio, which is the ratio of the opening area of the vent hole to the area of the molding surface with which the foam molding of the molding die contacts, is in the range of 0.5% to 1.0%. To do.

  The present invention also provides a molding apparatus having the mold and performing in-mold foam molding in the mold.

  According to the present invention, by performing in-mold foam molding with the opening ratio, which is the ratio of the opening area of the vent hole occupying the area of the molding surface with which the foam molded body is in contact, in the range of 0.5% to 1.0%. In addition, the flow of cationic antistatic agent from the pre-foamed particles during steam heating can be suppressed, and the same quality foamed molded product can be obtained under the same molding conditions as when the opening ratio is about 1.5 to 4.8%. It is done. Therefore, according to the present invention, even when the pre-foamed particles are in contact with water vapor, the loss of the cationic antistatic agent is reduced, and an antistatic thermoplastic foamed molded article having excellent antistatic properties at low cost is obtained. be able to.

The method for producing an antistatic thermoplastic resin foam molded article according to the present invention comprises preparing foamable thermoplastic resin particles in which a foaming agent is contained in thermoplastic resin particles and a cationic antistatic agent is attached to at least the particle surface. The foamable thermoplastic resin particles are heated and foamed to produce pre-foamed particles, and then the pre-foamed particles are filled into the cavities of a mold having cavities that match the desired molded body shape, and molded. In a method for producing an antistatic thermoplastic foam-molded article in which foam is produced by in-mold foam molding in which steam is flowed into a cavity through a vent hole of a mold and heated, and pre-foamed particles are expanded and fused. The opening ratio (hereinafter referred to as the opening ratio of the mold), which is the ratio of the opening area of the vent hole to the area of the molding surface with which the foamed molded body of the mold comes into contact, is 0.5% to 1. It is characterized by performing mold foaming as% range.
In the present invention, the “opening ratio” means that the area of the molding surface with which the foamed molded body of the mold comes into contact is A, and the total opening area of the vent holes opened in the molding surface is B ( B / A) refers to the aperture ratio calculated by 100 (%).

  In the method for producing an antistatic thermoplastic resin foam molded article of the present invention, examples of the thermoplastic resin constituting the thermoplastic resin foam molded article include polystyrene resins, polyethylene resins, polypropylene resins, and polyethylene terephthalate resins. Can be mentioned. Examples of polystyrene resins include polystyrene resins, copolymers of styrene and other monomers such as acrylic acid, high impact polystyrene resins, styrene modified polyolefin resins, and the like.

  In the method for producing an antistatic thermoplastic resin foam molded article of the present invention, the foamable thermoplastic resin particles are resin particles (beads) obtained by adding a foaming agent and a cationic antistatic agent to the thermoplastic resin. . The shape and average particle size of the foamable thermoplastic resin particles are not particularly limited, but the particle shape is preferably spherical. Further, the production method of the expandable thermoplastic resin particles can be appropriately selected according to the resin material to be used. For example, in the case of producing expandable resin particles made of a polystyrene resin, a suspension polymerization method or a melt extrusion method is used. Well-known bead manufacturing methods such as can be used.

  The foaming agent added to the foamable thermoplastic resin particles can be appropriately selected from foaming agents conventionally used in the production of thermoplastic resin foam molded articles such as polystyrene resin foam molded articles. Examples thereof include propane, n-butane, i-butane, n-pentane, i-pentane, cyclopentane, carbon dioxide gas, and nitrogen. These blowing agents may be used alone or in combination of two or more. it can.

As the cationic antistatic agent added to the foamable thermoplastic resin particles, the formula (1)
[(R ¹ ) ₄ N] ⁺ C ₂ H ₅ OSO ₃ ⁻ (1)
(Wherein R ¹ represents an optionally branched alkyl group having 1 to 17 carbon atoms) is preferably one or more selected from the group of compounds represented by:

In the method for producing an antistatic thermoplastic foam-molded article of the present invention, the cationic antistatic agent is an alkyl group having 3 to 3 carbon atoms out of the four R ¹ groups in the formula (1). It is preferable that

In the method for producing an antistatic thermoplastic foam-molded article of the present invention, the cationic antistatic agent is an alkyl group having 3 to 3 carbon atoms out of the four R ¹ groups in the formula (1). It is preferable that the remaining one is an alkyl group having 5 to 17 carbon atoms. Furthermore, the remaining one is more preferably an alkyl group having 9 to 14 carbon atoms.

  In the method for producing an antistatic thermoplastic resin foam molded article of the present invention, the expandable thermoplastic resin particles include, in addition to the foaming agent and the antistatic agent, a flame retardant, a flame retardant aid, an oxidation, if necessary. Additives such as an inhibitor, an ultraviolet absorber, a pigment, and a colorant may be contained.

  The foamable thermoplastic resin particles are prefoamed (primary foaming) to a desired bulk factor by a conventionally known prefoaming machine to obtain prefoamed particles.

  Next, the pre-expanded particles are filled into the cavities of the mold having a cavity that matches the desired shape of the molded body, heated by flowing steam into the cavities through the vent holes of the mold, and the pre-expanded particles A foam-molded product is produced by in-mold foam molding for expanding and fusing the material. In the present invention, the opening ratio of the mold is set in the range of 0.5% to 1.0%. When the opening ratio is less than 0.5%, the air permeability of the molding die is deteriorated, unevenness in heating occurs, or the fusion between the foamed particles becomes insufficient, and the machine of the foamed molded body to be obtained is obtained. Strength may be deteriorated. On the other hand, if the opening ratio exceeds 1.0%, the air permeability of the mold is improved, but the cationic antistatic agent tends to flow away from the surface of the foam molded article, and the resulting foam molded article has antistatic properties. It becomes easy to get worse.

  FIG. 1 is a cross-sectional view showing an example of a mold according to the present invention, and FIG. 2 is an enlarged cross-sectional view of a main part thereof. In these drawings, reference numeral 1 is a mold, 2 is a first mold part, 3 is a first mold (female mold), 4 is a second mold frame, 5 is a second mold (male mold), 6 is a cavity, 7 is a vent hole, 8 is a hole, and 9 is a ventilation member. The molding die 1 of this example includes a first mold part 2 and a second mold part 4 that are approached and separated from each other, and a first mold attached to the first mold part 2. 3 and a second mold attached to the second mold part 4. In addition, in this illustration, although the shaping | molding die 1 for shape | molding a box-shaped foaming molding is shown, the shape of a foaming molding is not limited to this illustration, According to the intended purpose of a foaming molding, it is various. The shape of the first and second molds can be variously changed accordingly.

  Moreover, the molding apparatus according to the present invention only needs to include the molding die 1 according to the present invention, and may include other components necessary for in-mold foam molding. For example, as the molding apparatus, the mold 1, a driving mechanism for moving any one of the mold sections so as to be mold-closed and mold-openable, and heating steam are supplied to the mold sections 2, 4. A water vapor supply source, an exhaust mechanism for exhausting each mold part 2, 4, a pipe for supplying pre-expanded particles into the cavity 6, and a cooling water supply for cooling each mold part 2, 4 Sources and the like.

  As shown in FIG. 2, each of the molds 3 and 5 is provided with a number of vent holes 7 for flowing water vapor from the outside of the molds 3 and 5 into the cavity 6 filled with the pre-expanded particles. These vent holes 7 are composed of holes 8 drilled in the respective molds 3 and 5 and ventilation members 9 mounted in the holes 8. In order to adjust the opening ratio of the mold 1, for example, the ventilation member 9 and a non-opening member (Mekura member) are appropriately combined with the mold 1 in which a large number of holes 8 are previously formed. It can implement by adjusting so that the aperture ratio of a type | mold may become the range of 0.5%-1.0%.

  The ventilation member 9 attached to the vent hole 7 has a bottomed cylindrical shape, and a plurality of small holes (lotus type) and a plurality of slits (slit type) are formed in the bottom. Yes. In the present invention, the opening shape of the ventilation member is preferably a lotus root type. Since the lotus root type has a smaller opening rate of the vent holes 7 than the slit type, it can be arranged evenly on the molding surface.

  In the case of performing in-mold foam molding using this mold 1, the mold is closed in a state where both mold parts 2, 4 are brought close to each other, and inside the cavity 6 formed between both molds 3, 5. The pre-expanded particles are filled, water vapor is flowed from the outside of the molds 3 and 5, and the pre-expanded particles are heated. By this heating, the pre-expanded particles are expanded, and the particles are fused to obtain a foamed molded product. After cooling the mold, the mold is opened and the foamed molded article is taken out.

  Thus, by performing in-mold foam molding with the opening ratio of the mold within the range of 0.5% to 1.0%, the flow of the cationic antistatic agent from the pre-foamed particles during steam heating can be suppressed, A foam-molded article of the same quality can be obtained under the same molding conditions as in the case of a normal opening ratio of about 1.5 to 4.8%. Therefore, even when pre-foamed particles with antistatic agent attached to the particle surface come into contact with water vapor, the flow of cationic antistatic agent is reduced, and the antistatic thermoplastic foamed with low cost and excellent antistatic properties. A molded body can be obtained. Since the foam-molded article obtained by the production method of the present invention is excellent in antistatic properties, it is suitably used, for example, as a substrate transport box.

[Example 1]
(Production of polyethylene resin pellets)
With respect to 100 parts by mass of an ethylene-vinyl acetate copolymer having a melt flow rate of 0.3 g / 10 min and a vinyl acetate content of 5.5% by mass, 0.3 part by mass of calcium silicate as a foam regulator and steer 0.1 parts by mass of calcium phosphate was added, and these were put into an extruder, heated and melted in the extruder and uniformly kneaded, and then extruded and granulated to prepare polyethylene resin pellets.

(Production of styrene-modified polyethylene resin particles)
40 parts by mass of the polyethylene resin pellets, 120 parts by mass of water, 0.45 parts by mass of magnesium pyrophosphate, and 0.02 parts by mass of sodium dodecylbenzenesulfonate are added to a pressure-resistant container with a stirrer having an internal volume of 100 liters and stirred. The temperature was raised to 85 ° C. Separately, 0.8 parts by mass of benzoyl peroxide as a radical polymerization initiator and 0.02 parts by mass of t-butylperoxybenzoate, and 0.8 parts by mass of dicumyl peroxide as a crosslinking agent were added to 60 parts by mass of a styrene monomer. The solution was dissolved to form a solution, and this solution was added to the aqueous medium in the pressure vessel, and the polymerization was carried out for 4 hours while being absorbed by the polyethylene resin pellets. Thereafter, the aqueous medium temperature was raised to 140 ° C. and held for 3 hours, and then cooled to take out styrene-modified polyethylene resin particles.

(Impregnation of foaming agent and foam molding)
To a V-type blender having an internal volume of 50 liters that can be sealed with a pressure resistance, 100 parts by mass of the styrene-modified polyethylene resin particles and a cationic antistatic agent, 2 trade names “Kachiogen ESO” manufactured by Daiichi Kogyo Seiyaku Co., Ltd. 0.04 parts by mass was added, and 14 parts by mass of butane was press-fitted as a foaming agent while stirring and sealing. Then, the inside of the vessel was kept at 50 ° C. for 4 hours, and the resin particles were impregnated with butane. Then, it cooled and took out the foamable thermoplastic resin particle.
Next, the taken-out foamable thermoplastic resin particles were immediately steam-heated with a batch-type foaming machine, pre-foamed to a bulk multiple of 30 times, and then the obtained pre-foamed particles were stored at room temperature for 24 hours.
Next, the pre-expanded particles were filled into a cavity of a mold having a length of 40 mm, a width of 300 mm, and a height of 30 mm, which was assembled in a foam molding apparatus (manufactured by Sekisui Koki Co., Ltd., Wiz-40LL). At this time, the vent hole set in the mold has a structure in which a lotus root type ventilation member having a small hole of φ0.8 mm × 24 holes is attached to a circular hole having a diameter of 10 mm formed in the mold. Yes, 234 vent holes were evenly arranged in the mold so that the opening ratio of the mold was 1.0%, and the other member was fitted with a mekura member.
Next, water vapor with a gauge pressure of 0.08 MPa was injected into the mold for 127 seconds to expand the pre-foamed particles in the mold to fuse the particle surfaces to each other, and after cooling, the foamed molded article was taken out. .

When the surface resistivity of the obtained foamed molded product was measured, it was 1 × 10 ¹² Ω or less and was excellent in antistatic performance.
The surface resistivity was measured as follows.

<Measurement method of surface resistivity>
Measured according to the method described in JIS K6911: 1995 “General Test Method for Thermosetting Plastics”. As test equipment, a digital ultra-high resistance / microammeter R8340 and a resiliency chamber R12702A manufactured by Advantest Co., Ltd. are used, and an electrode is pressure-bonded to a sample sample (foamed molded body) with a load of about 30 N, and 1 at 500V. The resistance value after charging for a minute was measured, and the surface resistivity was calculated by the following formula (2). The sample sample was 100 mm × 100 mm × 25 mm, the measurement surface (100 mm × 100 mm) was used as the skin surface, 10 samples were cut out from the same foamed molded product, and each was measured. If the surface resistivity was 1 × 10 ¹² Ω or less, the foamed molded article was judged to have antistatic properties.
ρs = π (D + d) / (D−d) × Rs (2)
(Wherein ρs represents the surface resistivity (MΩ), D represents the inner diameter (cm) of the annular electrode on the surface, d represents the outer diameter (cm) of the inner circle of the surface electrode, and Rs represents the surface resistance (MΩ).

[Example 2]
Place 117 loton type (φ0.8mm × 24 small holes within 10mm diameter) vent holes evenly in the mold so that the mold opening ratio is 0.5%. Was fitted with a mekura member. Otherwise, a foamed molded article was produced in the same manner as in Example 1, and the surface resistivity was measured. The obtained foamed molded article had a surface resistivity of 1 × 10 ¹² Ω or less, and was excellent in antistatic performance.

[Example 3]
The ventilation member attached to the vent hole is a slit mold in which six slits having a width of 0.3 mm are opened within a diameter of 10 mm, and 180 vent holes are formed so that the opening ratio of the mold is 1.0%. Were placed evenly on the mold, and the other holes were fitted with mekura members. Otherwise, a foamed molded article was produced in the same manner as in Example 1, and the surface resistivity was measured. The obtained foamed molded article had a surface resistivity of 1 × 10 ¹² Ω or less, and was excellent in antistatic performance.

[Comparative Example 1]
1123 lotus-shaped vent holes (φ0.8 mm × 24 small holes in a diameter of 10 mm) were evenly arranged in the mold so that the opening ratio of the mold was 4.8%. Otherwise, a foamed molded article was produced in the same manner as in Example 1, and the surface resistivity was measured. As a result, the surface resistivity of the obtained foamed molded article was 10 ¹³ Ω or more, and the antistatic performance was inferior.

[Comparative Example 2]
Arrange 351 lotus-shaped vent holes (φ0.8 mm × 24 small holes within a diameter of 10 mm) evenly in the mold so that the opening ratio of the mold is 1.5%. Was fitted with a mekura member. Otherwise, a foamed molded article was produced in the same manner as in Example 1, and the surface resistivity was measured. As a result, the surface resistivity of the obtained foamed molded article was 1 × 10 ¹³ Ω or more, and the antistatic performance was inferior.

[Comparative Example 3]
Seventy loton type vent holes were evenly arranged in the mold so that the opening ratio of the mold was 0.3%, and the other members were fitted with mekura members. Otherwise, a foamed molded article was produced in the same manner as in Example 1. However, the obtained foamed molded article was unsuitable for practical use because the degree of fusion between the foamed particles was low and the mechanical strength was low. .

From the test results of Examples 1 to 3 and Comparative Examples 1 to 3 described above, the results are obtained in Examples 1 to 3 according to the present invention in which the opening ratio of the mold is in the range of 0.5% to 1.0%. The surface resistivity of the foamed molded product was 1 × 10 ¹² Ω or less, and it was found that a foamed molded product excellent in antistatic performance was obtained. Moreover, practically sufficient mechanical strength was obtained for the foam molded articles produced in Examples 1 to 3.

On the other hand, in Comparative Examples 1 and 2 in which the aperture ratio exceeded the aperture ratio range of the present invention, the surface resistivity of the obtained foamed molded product was higher than 1 × 10 ¹² Ω, and the antistatic performance was inferior. This is presumably because when the pre-expanded particles were brought into contact with water vapor, the antistatic agent adhering to the particle surface was washed away, so that the surface resistivity increased.
Further, in Comparative Example 3 in which the aperture ratio was less than the aperture ratio range of the present invention, a foamed molded article having a practically sufficient mechanical strength could not be obtained.

It is sectional drawing which shows an example of the shaping | molding die concerning this invention. It is a principal part expanded sectional view of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Molding die, 2 ... 1st mold part, 3 ... 1st type | mold, 4 ... 2nd mold frame, 5 ... 2nd type | mold, 6 ... Cavity, 7 ... Vent hole, 8 ... Hole, 9 ... ventilation member.

Claims (8)

Preparation of foamable thermoplastic resin particles in which a foaming agent is contained in the thermoplastic resin particles and a cationic antistatic agent is attached to at least the particle surface, and the foamable thermoplastic resin particles are heated and foamed to be prefoamed particles Then, the pre-expanded particles are filled into the cavity of a mold having a cavity matching the desired shape of the molded body, heated by flowing steam into the cavity through the vent hole of the mold, and pre-expanded In the method for producing an antistatic thermoplastic resin foam molded article in which a foam molded article is produced by performing in-mold foam molding for expanding and fusing particles,
In-mold foam molding is performed by setting the opening ratio, which is the ratio of the opening area of the vent hole to the area of the molding surface in contact with the foam molded body of the molding die, in the range of 0.5% to 1.0%. A process for producing an antistatic thermoplastic resin foam molded article. The cationic antistatic agent has the formula (1)
[(R ¹ ) ₄ N] ⁺ C ₂ H ₅ OSO ₃ ⁻ (1)
(Wherein R ¹ represents an optionally branched alkyl group having 1 to 17 carbon atoms) is one or more selected from the group of compounds represented by the formula: 2. A method for producing an antistatic thermoplastic resin foam molded article according to 1. 3. The antistatic heat according to claim 2, wherein three of the four R ¹ groups in the formula (1) are alkyl groups having 1 to 3 carbon atoms as the cationic antistatic agent. A method for producing a plastic resin foam molded article. In the cationic antistatic agent, three of the four R ¹ groups in the formula (1) are alkyl groups having 1 to 3 carbon atoms, and the remaining one is an alkyl group having 5 to 17 carbon atoms. The manufacturing method of the antistatic thermoplastic resin foaming molding of Claim 3 characterized by the above-mentioned.   5. The antistatic device according to claim 1, wherein the vent hole is formed by mounting a lotus root type ventilation member having a large number of small holes formed in a hole formed in the mold. Method for producing a foamed thermoplastic resin molded article.   An antistatic thermoplastic resin foam molded article obtained by the method for producing an antistatic thermoplastic resin foam molded article according to any one of claims 1 to 5. A mold for producing an antistatic thermoplastic resin foam molded article used in the method for producing an antistatic thermoplastic resin foam molded article according to any one of claims 1 to 5,
The antistatic heat, wherein the opening ratio, which is the ratio of the opening area of the vent hole to the area of the molding surface with which the foamed molded body of the mold comes into contact, is in the range of 0.5% to 1.0%. Mold for manufacturing plastic resin foam moldings.   An antistatic thermoplastic resin foam molded article for manufacturing an antistatic thermoplastic resin foam molded article, comprising the mold for producing an antistatic thermoplastic resin foam molded article according to claim 7 and performing in-mold foam molding in the mold. Molding equipment.

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