JP2017078108A - Foam molding and method for producing the same, and method for producing resin material for foam molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a foam molded product, a foam molded product, and a method for producing a resin material for a foam molded product capable of producing a foam molded product having a small surface roughness and an excellent appearance.
SOLUTION: A method for producing a foam molded article includes a foam part having bubbles inside, and a skin layer containing an elastomer C formed so as to be integrated with the foam part and cover the surface thereof. A method for producing a foam-molded article, comprising an amorphous thermoplastic resin A, a crystalline thermoplastic resin B having a melting point higher than the glass transition point of the amorphous thermoplastic resin A, and Using an elastomer C other than the crystalline thermoplastic resin B, (1) a primary kneading step of kneading the crystalline thermoplastic resin B and the elastomer C, and (2) a kneaded product obtained by the primary kneading step And a non-crystalline thermoplastic resin A, and (3) a molding step in which a foaming agent is added to the kneaded product obtained by the secondary kneading step and injection molding is performed. And
[Selection] Figure 1

Description

  The present invention relates to a foam molded article, a method for producing the same, and a method for producing a resin material for a foam molded article for forming a foam molded article.

  For example, as molded products used in automobiles and office automation equipment, foaming with bubbles (foam cells) and microcapsules inside solid components made of resin, etc., for the purpose of reducing weight and reducing the amount of raw materials used. Use of a molded body (see, for example, Patent Documents 1 to 4) is performed.

  However, the foam molded article has a problem that the surface roughness increases due to foaming. When the surface roughness of the foamed molded product is increased, the foamed product is whitened and gloss is decreased, and the appearance is impaired. The reason why the surface roughness of the foamed molding increases is that when the molten resin comes into contact with the mold surface during injection molding and is cooled and solidified, the surface is broken with bubbles (swirl marks) or silver. It is thought that streaks remain.

In order to solve such a problem, conventionally, it has been necessary to raise the mold temperature to near the glass transition point (Tg) of the resin.
However, when the mold temperature is raised, the cooling time is inevitably increased, and therefore the molding time becomes longer.
In addition, in a foamed molded article containing microcapsules, a foamed molded article is formed using a thermally expandable microcapsule. However, molding must be performed under conditions that do not break the thermally expandable microcapsule. There is a problem.

JP 2011-37925 A JP 2001-151963 A WO2004 / 046243 JP 2008-150476 A

As a result of repeated studies by the present inventors, the surface roughness of the foam molded article obtained by adding an elastomer (rubber component) having a low glass transition point (Tg) to the resin material for forming the foam molded article. It was found that can be reduced.
However, it is difficult to maintain foaming simply by adding a rubber component having a low glass transition point (Tg), and thus it is difficult to reduce the weight.

  The present invention has been made on the basis of the above circumstances, and its purpose is to provide a foamed molded product that can produce a foamed molded product having a small surface roughness and excellent appearance, and the manufacturing method. It is providing the manufacturing method of the obtained foaming molding and the resin material for foaming moldings for forming the said foaming molding.

The method for producing a foamed molded article of the present invention includes a foam part having bubbles inside and a skin layer containing an elastomer C formed so as to be integrated with the foam part and cover the surface thereof. A method for producing a molded body, comprising:
Amorphous thermoplastic resin A, a crystalline thermoplastic resin B having a melting point (Tm) higher than the glass transition point (Tg) of the amorphous thermoplastic resin A, and the crystalline thermoplastic resin Using elastomer C other than resin B,
(1) a primary kneading step of kneading the crystalline thermoplastic resin B and the elastomer C;
(2) a secondary kneading step of kneading the kneaded product obtained by the primary kneading step and the amorphous thermoplastic resin A;
(3) It has a molding step of adding a foaming agent to the kneaded material obtained by the secondary kneading step and injection molding.

  In the manufacturing method of the foaming molding of this invention, it is preferable that the said amorphous thermoplastic resin A is a styrene resin.

  In the method for producing a foamed molded article of the present invention, the crystalline thermoplastic resin B has a melting point (Tm) higher by 50 ° C. or more than the glass transition point (Tg) of the styrenic resin. preferable.

  In the method for producing a foamed molded product of the present invention, the crystalline thermoplastic resin B is preferably a polyester resin, a polyamide resin or a fluororesin.

  In the method for producing a foam molded article of the present invention, the elastomer C is a copolymer of an alkyl methacrylate and / or an alkyl acrylate and an organosiloxane monomer, and the alkyl methacrylate and / or the alkyl acrylate. Is preferably used in a monomer unit of 50% or more.

  In the method for producing a foamed molded article of the present invention, the kneading temperature in the primary kneading step is preferably less than the melting point (Tm) of the crystalline thermoplastic resin B.

The method for producing a resin material for a foam molded article of the present invention includes a foam part having bubbles inside, a skin layer containing an elastomer C formed so as to be integrated with the foam part and cover the surface thereof, A method for producing a resin material for a foam molded article used for injection molding for producing a foam molded article having
Amorphous thermoplastic resin A, a crystalline thermoplastic resin B having a melting point (Tm) higher than the glass transition point (Tg) of the amorphous thermoplastic resin A, and the crystalline thermoplastic resin Using elastomer C other than resin B,
(1) a primary kneading step of kneading the crystalline thermoplastic resin B and the elastomer C;
(2) A kneaded product obtained by the primary kneading step and a secondary kneading step of kneading the amorphous thermoplastic resin A are characterized.

The foamed molded article of the present invention comprises a foam part having bubbles inside, and a skin layer having a thickness of 50 μm or more that does not have bubbles, and is formed so as to be integrated with the foam part and cover the surface thereof. A foamed molded article in which the skin layer contains elastomer C,
The weight reduction rate is 10-50%,
The surface roughness Rz is 3 μm or less,
Elastomer C is characterized by being present in the skin layer more than in the foam part.

  According to the method for producing a foamed molded article of the present invention, a foamed molded article having a small surface roughness and an excellent appearance can be produced by injection molding while having light bubbles and being reduced in weight.

It is a schematic cross section for demonstrating the foaming molding of this invention.

Hereinafter, the present invention will be described in detail.
[Method for producing foam molded article]
FIG. 1 is a schematic cross-sectional view for explaining a foamed molded article of the present invention.
The method for producing a foamed molded article of the present invention includes a foam part 10 having bubbles 15 inside, and a skin layer 12 containing an elastomer C formed so as to be integrated with the foam part 10 and cover the surface thereof. Is a method for producing a foamed molded article having the following.
Specifically, an amorphous thermoplastic resin A (hereinafter also referred to as “amorphous resin A”) and a melting point (Tm) higher than the glass transition point (Tg) of the amorphous resin A. Using the crystalline thermoplastic resin B (hereinafter also referred to as “crystalline resin B”) and an elastomer C other than the crystalline resin B (hereinafter also referred to as “rubber component C”), the following ( It has at least the steps of 1) to (3).
(1) Primary kneading step in which crystalline resin B and rubber component C are kneaded (2) Kneaded product (crystalline resin composition) obtained in the primary kneading step and amorphous resin A are kneaded and foamed. Secondary kneading step for producing body resin material (3) Molding step of adding an foaming agent to the resin material for foam molded body obtained by the secondary kneading step to obtain an injection molding material and injection molding this

[Amorphous resin A]
Examples of the amorphous thermoplastic resin A that forms the foamed molded article of the present invention include styrene resins and polycarbonate resins. Among these, it is preferable to use a styrene resin because the change in viscosity with respect to temperature is small and foaming is easy. These can be used individually by 1 type or in combination of 2 or more types.

The glass transition point (Tg) of the amorphous resin A is preferably 90 to 150 ° C., for example.
When the glass transition point (Tg) of the amorphous resin A is too small, the foamed molded product obtained may be low in strength. On the other hand, when the glass transition point (Tg) of the amorphous resin A is excessive, a sufficient temperature difference from the melting point (Tm) of the crystalline resin B cannot be ensured. A cannot be sufficiently moved to the inner region of the mold, and as a result, there is a possibility that the skin layer composed of the crystalline resin B and the rubber component C cannot be reliably formed.

  The glass transition point (Tg) of the amorphous resin A is a frequency of 6.28 rad / sec and a temperature of 220 ° C. using a viscoelasticity measuring device “ARES-G2” (manufactured by TA Instruments Japan). It is measured as the peak temperature of tan δ under the condition of measuring while decreasing the temperature from ˜80 ° C. at 2 ° C./min.

Content of the amorphous resin A in the resin material for foam molded bodies is 70 to 93 parts by mass in 100 parts by mass of the resin material for foam molded bodies.
When the content of the amorphous resin A in the resin material for the foam molded article is excessive, a skin layer having a desired thickness cannot be formed, and the resulting foam molded article has a small surface roughness. There is a risk that it cannot be done. On the other hand, when the content of the amorphous resin A in the resin material for the foam molded article is too small, the foam part of the desired size cannot be formed, and the resulting foam molded article has a weight reduction rate. May be low.

[Crystalline resin B]
Examples of the crystalline thermoplastic resin B that forms the foamed molded article of the present invention include polyester resins, polyamide resins, fluororesins, polypropylene resins, and polyethylene resins. These can be used individually by 1 type or in combination of 2 or more types.

The melting point (Tm) of the crystalline resin B is higher than the glass transition point (Tg) of the amorphous resin A, and is preferably 200 to 300 ° C., for example.
The difference between the melting point (Tm) of the crystalline resin B and the glass transition point (Tg) of the amorphous resin A is preferably 50 ° C. or higher.
By using the crystalline resin B having a melting point (Tm) higher than the glass transition point (Tg) of the amorphous resin A by 50 ° C. or higher, the melting point (Tm) of the crystalline resin B and the amorphous resin A A sufficient temperature difference from the glass transition point (Tg) of the crystalline resin B is ensured in the molding process, and the amorphous resin A loses its fluidity in the molding process. ) It is possible to secure a sufficient time until the fluid is cooled to the following and loses fluidity. Therefore, the amorphous resin A can be reliably moved to the inner region of the mold, and as a result, the skin layer Can be reliably formed.

  In addition, when the melting point (Tm) of the crystalline resin B is excessively small, a sufficient temperature difference from the glass transition point (Tg) of the amorphous resin A cannot be ensured. A cannot be sufficiently moved to the inner region of the mold, and as a result, there is a possibility that the skin layer composed of the crystalline resin B and the rubber component C cannot be reliably formed. On the other hand, when the melting point (Tm) of the crystalline resin B is excessive, the kneading temperature and the cylinder temperature at the time of injection molding must be increased, and the amorphous resin A may be thermally decomposed.

  The melting point (Tm) of the crystalline resin B is a temperature showing the minimum value of the melting peak under the condition that the temperature is raised from room temperature to 10 ° C./min using DSC “Diamond DSC” (manufactured by PerkinElmer Japan). It is to be measured.

Content of crystalline resin B in the resin material for foam molded articles is 5 to 25 parts by mass in 100 parts by mass of the resin material for foam molded articles.
When the content of the crystalline resin B in the resin material for the foam molded body is excessive, the resin material for the foam molded body and the injection molding material obtained therefrom have low fluidity. It may be difficult to pour the material. On the other hand, when the content of the crystalline resin B in the resin material for the foam molded body is too small, a skin layer having the desired thickness cannot be formed, and the resulting foam molded body has a small surface roughness. It may not be possible.

[Rubber component C]
The elastomer C (rubber component C) forming the foamed molded article of the present invention preferably has a glass transition point (Tg) of −60 to −20 ° C.
Examples of the rubber component C include butadiene rubber, ethylene propylene rubber, chloroprene rubber, acrylonitrile butadiene rubber, and silicone acrylic rubber. These can be used individually by 1 type or in combination of 2 or more types.
The rubber component C is a copolymer of an alkyl methacrylate and / or an alkyl acrylate and an organosiloxane monomer such as a dimethylsiloxane monomer, and the alkyl methacrylate and / or the alkyl acrylate is 50% or more in monomer units. It is particularly preferable to use the used silicone acrylic rubber.

  When the glass transition point of the rubber component C is −20 ° C. or lower, the rubber component C can move even at a low temperature due to its high molecular mobility. Therefore, the surface shape of the mold can be transferred with high accuracy, and as a result, the surface roughness of the obtained foamed molded product can be reduced. Moreover, when the glass transition point of the rubber component C is lower than −60 ° C., the molecular mobility is excessively high and the rubber component is likely to move, and as a result, it may be difficult to maintain foaming.

The content of the rubber component C contained in the resin material for foam molded bodies is 2 to 15 parts by mass in 100 parts by mass of the resin material for foam molded bodies.
When the content of the rubber component C is excessive, the obtained foamed molded product may be low in strength. On the other hand, when the content of the rubber component C is too small, there is a possibility that the obtained foamed molded article cannot have a desired low surface roughness.

[Foaming agent]
As the foaming agent, an organic chemical foaming agent and an inorganic chemical foaming agent can be used.
As the organic chemical foaming agent, polycarboxylic acid, azo compound, nitroso compound, hydrazine derivative, semicarbazide compound and the like can be used.
Examples of the inorganic chemical foaming agent include bicarbonate, carbonate, organic acid metal salt, nitrite and the like.

Specific examples of the polycarboxylic acid in the organic chemical foaming agent include citric acid, oxalic acid, fumaric acid, and phthalic acid.
Specific examples of the azo compound include azodicarbonamide (ADCA), 1,1′-azobis (1-acetoxy-1-phenylethane), dimethyl-2,2′-azobisbutyrate, dimethyl-2,2 ′. -Azobisisobutyrate, 2,2'-azobis (2,4,4-trimethylpentane), 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis [N- (2 -Carboxyethyl) -2-methyl-propionamidine] and the like.
Specific examples of the nitroso compound include N, N′-dinitrosopentamethylenetetramine (DPT).
Specific examples of the hydrazine derivative include 4,4′-oxybis (benzenesulfonylhydrazide), diphenylsulfone-3,3′-disulfonylhydrazide and the like.
Specific examples of the semicarbazide compound include p-toluenesulfonyl semicarbazide.
Specific examples of other organic chemical foaming agents include trihydrazinotriazine.

In the inorganic chemical foaming agent, specific examples of the bicarbonate include sodium bicarbonate and ammonium bicarbonate.
Specific examples of the carbonate include sodium carbonate and ammonium carbonate.
Specific examples of the organic acid metal salt include sodium citrate.
Specific examples of nitrite include ammonium nitrite.

  Of these foaming agents, it is preferable to use a foaming agent that does not decompose below the melting temperature of the resin constituting the foamed molded article but decomposes below the decomposition temperature. As such a foaming agent, azodicarbonamide (ADCA), sodium bicarbonate, citric acid, sodium citrate and the like can be preferably used. In particular, it is preferable to use sodium hydrogen carbonate from the viewpoint of preventing odor and color unevenness from occurring in the obtained foamed molded article.

  As the foaming agent, it is preferable to use a foaming gas whose main component is a nonflammable gas. Specific examples of such foaming agents include nitrogen gas and carbon dioxide-generating foaming agents such as azodicarbonamide, and carbon dioxide-generating foaming agents such as sodium hydrogen carbonate, Examples of the blowing agent that generates nitrogen gas include dinitrosopentamethylenetetramine, p, p′-oxybisbenzenesulfonylhydrazide, and the like.

  The amount of the foaming agent added to the resin material for the foamed molded product is determined in consideration of the type of foaming agent, the weight reduction rate of the foamed molded product, etc. It is 0.2-10 mass parts with respect to 100 mass parts.

[Other ingredients]
In the resin material for foam molded articles, other components other than the foaming agent may be contained.
Other components include reinforcing agents, dispersants, pigments and colorants, fillers, crystallization accelerators, clearing agents, foam inhibitors, flame retardants, flame retardant aids, antistatic agents, processing aids, lubricants. Organic peroxides, plasticizers, photocatalysts, and the like can be used. These other components may be used alone or in combination of two or more.
As the reinforcing agent, carbon black, silica, glass fiber, carbon fiber, cellulose fiber, aramid fiber, or the like can be used.
As the dispersant, wax, modified wax, metal soap, low molecular weight polyethylene, low molecular weight polypropylene and the like can be used.
As the wax, paraffin wax, polyolefin wax, or the like can be used.
As the modified wax, for example, a wax having an acidic group in the molecular structure can be used. Specific examples thereof include maleic acid-modified wax, fumaric acid-modified wax, acrylic acid-modified wax, methacrylic acid-modified wax, crotonic acid. Examples thereof include modified waxes. As the metal soap, sodium salts, calcium salts, zinc salts, magnesium salts, and aluminum salts of fatty acids such as stearic acid, hydroxystearic acid, behenic acid, montanic acid, lauric acid, and sebacic acid can be used.
As the pigment and colorant, inorganic pigments and inorganic pigments can be used. Specific examples of inorganic pigments include petals, titanium oxide, cadmium red, cadmium yellow, zinc oxide, ultramarine, cobalt blue, calcium carbonate, titanium yellow, lead white, red lead, lead yellow, and bitumen. Specific examples of the organic pigment include quinacridone, polyazo yellow, anthraquinone yellow, polyazo red, azo lake yellow, perylene, phthalocyanine blue, phthalocyanine green, and isoindolinone yellow.

[Primary training process]
In the primary kneading step, the crystalline resin B and the rubber component C are kneaded.
The kneading temperature in the primary kneading step is preferably less than the melting point (Tm) of the crystalline resin B.
Since the kneading temperature in the primary kneading step is lower than the melting point (Tm) of the crystalline resin B, the kneading is performed in a state where the viscosity of the crystalline resin B is high, so that a large shearing force can be applied and the crystallinity can be increased. The interaction between the resin B and the rubber component C can be increased, and as a result, the rubber component C can be dispersed in the crystalline resin B with high dispersibility.

[Secondary training process]
In the secondary kneading step, the crystalline resin composition obtained by the primary kneading step and the amorphous resin A are kneaded.
The kneading temperature in the secondary kneading step can be set to 160 to 280 ° C., for example.

[Molding process]
In the molding step, an injection molding material is obtained by adding a foaming agent to the resin material for foam molding obtained in the secondary kneading step, and this is injection molded.
Specifically, an injection molding material in which a foaming agent is dry blended with a resin material for a foam molding is put into an injection molding machine, and the foaming agent is decomposed in a cylinder to generate gas. When charged into the mold from the cylinder, the crystalline resin B, which was cooled to below the melting point and rapidly increased in viscosity on the mold surface, was cooled and solidified, and dispersed in the crystalline resin B and the crystalline resin B. A skin layer 12 made of the rubber component C is formed. Since the amorphous resin A can flow at a temperature above the glass transition point, it takes longer than the crystalline resin B to cool to below the glass transition point and lose fluidity. For this reason, the amorphous resin A is moved to the inner region spaced from the mold surface, and the gas expands in the inner region to form the bubbles 15 to form the foam portion 10. The body is obtained.
In the skin layer 12, the rubber component C that can move even at a low temperature (room temperature) is pressed against the surface of the mold by the pressure of foaming, whereby the surface shape of the mold is transferred with high accuracy.

  The molding temperature varies depending on the glass transition point (Tg) of the amorphous resin A to be used, the melting point (Tm) of the crystalline resin B, and the type of the rubber component C. For example, the cylinder temperature is 180 to 300 ° C., the mold It is preferable that temperature is 30-120 degreeC.

  According to the method for producing a foamed molded article as described above, the crystalline resin B having the bubbles 15 and being solidified in advance because the rubber component C has a high melting point while being reduced in weight. Since the rubber component C is sufficiently kneaded in advance, the rubber component C can be unevenly distributed in the skin layer 12 of the foam molded article, and as a result, a foam molded article having a small surface roughness and excellent appearance can be produced by injection molding. it can.

[Foamed molded product]
The foamed molded product of the present invention has a foam part 10 having air bubbles 15 therein, and is formed so as to be integrated with the foam part 10 so as to cover the surface, and has a thickness of 50 μm or more with almost no air bubbles. And a skin layer 12.
In this foam molded article, the elastomer C is present in the skin layer 12 more than the foam part 10.

  The thickness of the skin layer 12 in the foamed molded product is determined by cutting the foamed molded product and analyzing the cross-section of the bubbles initially present from the end on the surface side in an image obtained by a laser microscope “VK9510” (manufactured by Keyence). The distance to the position is measured to obtain the thickness of the skin layer, which is calculated for any 10 locations and calculated as the average value.

  The skin layer 12 in the foamed molded product may have a form that covers not only the foam part 10 but also a part of the foam part 10.

[Bubbles]
It is preferable that the main component of the gas filled in the bubbles 15 included in the foam molded article is a nonflammable gas. Here, “non-combustible gas” means a gas that does not contribute to combustion other than combustible gas (for example, hydrogen gas, hydrocarbon gas, ammonia gas, etc.) and combustion-supporting gas (for example, oxygen gas, halogen gas, etc.). To do.
Specific examples of such incombustible gas include nitrogen gas and carbon dioxide gas.
It is preferable that the ratio of nonflammable gas among the gas with which the bubble 15 is filled is 95 mol% or more.

  The weight reduction rate of the foamed molded product of the present invention is 10 to 50%, preferably 15 to 50%. When the weight reduction rate is excessively small, it is difficult to reduce the weight sufficiently.

The weight reduction rate of the foam molded body is calculated according to the following formula (a), where P0 is the specific gravity of the unfoamed solid molded body of the resin material constituting the foam molded body and P1 is the specific gravity of the foam molded body. Is.
Formula (a): Weight reduction rate = ({P0−P1} / P0) × 100

  The foamed molded article of the present invention is obtained by injection molding using a mold having a surface roughness Rz of 2 μm, and has a surface roughness Rz of 3 μm or less.

  The surface roughness Rz of the foamed molded product is calculated as a 10-point average roughness by analyzing an image obtained by observing the surface with a laser microscope “VK-X100” (manufactured by Keyence Corporation).

  The shape of the foamed molded product of the present invention is not particularly limited, and can be configured to have an appropriate shape such as a plate shape, a cylindrical shape, a square shape, a spherical shape, and the like according to various applications. .

  As mentioned above, although embodiment of this invention was described concretely, embodiment of this invention is not limited to said example, A various change can be added.

  Hereinafter, specific examples of the present invention will be described, but the present invention is not limited thereto.

[Example 1: Production Example 1 of Foam Molded Article]
Using a twin-screw kneader “KTX-30” (manufactured by Kobe Steel), 100 parts by mass of polypropylene “MA3” (manufactured by Nippon Polypro Co., Ltd.) and 50 parts by mass of silicone acrylic rubber were added at a cylinder temperature of 210 ° C. and screw rotation. It knead | mixed on the conditions of several 300 rpm (primary kneading process).
15 parts by mass of the obtained kneaded product and 85 parts by mass of polystyrene resin “Dick Styrene XC515” (manufactured by DIC) were kneaded under the conditions of a cylinder temperature of 210 ° C. and a screw rotation speed of 300 rpm (secondary kneading step). Thus, the pellet which consists of a resin material for foaming moldings of this invention was obtained.
After adding 2 parts by mass of the chemical foaming agent “Cermic 6074MB” (manufactured by Sankyo Kasei Co., Ltd.) to the obtained pellets and dry blending, an injection molding machine “J1 40AD-110H” (manufactured by Nippon Steel Works) was used. A bending test piece having a shape in accordance with JIS K7110 (K7111) was produced under the molding conditions of a cylinder temperature of 230 ° C., a mold temperature of 50 ° C., an injection speed of 30 mm / sec, and a holding pressure of 5 MPa (molding step). The mold used has a surface roughness Rz of 2 μm on the inner surface.
Let this test piece be a foaming molding [1].

[Example 2]
Using a twin-screw kneader “KTX-30” (manufactured by Kobe Steel), 100 parts by mass of polyamide 6 “1030B” (manufactured by Ube Industries) and 50 parts by mass of silicone acrylic rubber were added at a cylinder temperature of 210 ° C. and screw rotation. It knead | mixed on the conditions of several 300 rpm (primary kneading process).
15 parts by mass of the obtained kneaded product and 85 parts by mass of polystyrene resin “Dick Styrene XC515” (manufactured by DIC) were kneaded under the conditions of a cylinder temperature of 210 ° C. and a screw rotation speed of 300 rpm (secondary kneading step).
Subsequent steps were carried out in the same manner as in Example 1 to obtain a foamed molded product [2].

Example 3
Using a twin-screw kneader “KTX-30” (manufactured by Kobe Steel), 100 parts by mass of PTFE “Polyflon MPA” (manufactured by Daikin Industries, Ltd.) and 50 parts by mass of silicone acrylic rubber were added at a cylinder temperature of 270. It knead | mixed on the conditions of (degreeC) and screw rotation speed 300rpm (primary kneading process).
15 parts by mass of the obtained kneaded material and 85 parts by mass of polystyrene resin “Dick Styrene XC515” (manufactured by DIC) were kneaded under the conditions of a cylinder temperature of 230 ° C. and a screw rotation speed of 300 rpm (secondary kneading step).
Subsequent steps were performed in the same manner as in Example 1 to obtain a foamed molded product [3].

Example 4
Using a biaxial kneader “KTX-30” (manufactured by Kobe Steel), 100 parts by mass of polyethylene “Novatech HB420R” (manufactured by Nippon Polyethylene Co., Ltd.) and 50 parts by mass of silicone acrylic rubber, a cylinder temperature of 210 ° C. and a screw It knead | mixed on the conditions of rotation speed 300rpm (primary kneading process).
15 parts by mass of the obtained kneaded product and 85 parts by mass of polystyrene resin “Dick Styrene XC515” (manufactured by DIC) were kneaded under the conditions of a cylinder temperature of 210 ° C. and a screw rotation speed of 300 rpm (secondary kneading step).
Subsequent steps were performed in the same manner as in Example 1 to obtain a foamed molded product [4].

Example 5
Using a biaxial kneader “KTX-30” (manufactured by Kobe Steel), 100 parts by mass of polyester “EMC355” (manufactured by Toyobo Co., Ltd.) and 50 parts by mass of silicone acrylic rubber were added at a cylinder temperature of 250 ° C. It knead | mixed on the conditions of screw rotation speed 300rpm (primary kneading process).
15 parts by mass of the obtained kneaded material and 85 parts by mass of polystyrene resin “Dick Styrene XC515” (manufactured by DIC) were kneaded under the conditions of a cylinder temperature of 230 ° C. and a screw rotation speed of 300 rpm (secondary kneading step).
Subsequent steps were performed in the same manner as in Example 1 to obtain a foamed molded product [5].

[Comparative Example 1]
Using a biaxial kneader “KTX-30” (manufactured by Kobe Steel), 85 parts by mass of polystyrene resin “Dick Styrene XC515” (manufactured by DIC), 10 parts by mass of “polyamide 6” and 5 parts by mass of silicone acrylic rubber Was kneaded under conditions of a cylinder temperature of 210 ° C. and a screw rotation speed of 300 rpm.
After adding 2 parts by mass of the chemical foaming agent “Cermic 6074MB” (manufactured by Sankyo Kasei Co., Ltd.) to the obtained pellets and dry blending, an injection molding machine “J1 40AD-110H” (manufactured by Nippon Steel Works) was used. A bending test piece having a shape according to JIS K7110 (K7111) was produced under molding conditions of a cylinder temperature of 230 ° C., a mold temperature of 50 ° C., an injection speed of 30 mm / sec, and a holding pressure of 5 MPa.
This test piece is used as a comparative foam molded article [6].

[Comparative Example 2]
Using a biaxial kneader “KTX-30” (manufactured by Kobe Steel), 85 parts by mass of polystyrene resin “Dick Styrene XC515” (manufactured by DIC) and 5 parts by mass of silicone acrylic rubber were added at a cylinder temperature of 210 ° C. It knead | mixed on the conditions of screw rotation speed 300rpm.
The obtained kneaded material and 10 parts by mass of “polyamide 6” were kneaded under the conditions of a cylinder temperature of 210 ° C. and a screw rotation speed of 300 rpm.
After adding 2 parts by mass of the chemical foaming agent “Cermic 6074MB” (manufactured by Sankyo Kasei Co., Ltd.) to the obtained pellets and dry blending, an injection molding machine “J1 40AD-110H” (manufactured by Nippon Steel Works) was used. A bending test piece having a shape according to JIS K7110 (K7111) was produced under molding conditions of a cylinder temperature of 230 ° C., a mold temperature of 50 ° C., an injection speed of 30 mm / sec, and a holding pressure of 5 MPa.
This test piece is used as a comparative foam molded article [7].

[Comparative Example 3]
Using a twin-screw kneader “KTX-30” (manufactured by Kobe Steel), 100 parts by mass of polycarbonate “Caliver 301-10” (manufactured by Sumika Stylon Polycarbonate) and 50 parts by mass of silicone acrylic rubber were added to the cylinder temperature. It knead | mixed on the conditions of 260 degreeC and screw rotation speed 300rpm (primary kneading process).
15 parts by mass of the obtained kneaded material and 85 parts by mass of polystyrene resin “Dick Styrene XC515” (manufactured by DIC) were kneaded under the conditions of a cylinder temperature of 230 ° C. and a screw rotation speed of 300 rpm (secondary kneading step).
Subsequent steps were carried out in the same manner as in Example 1 to obtain a foamed molded product [8].

[Comparative Example 4]
Using a biaxial kneader “KTX-30” (manufactured by Kobe Steel), 100 parts by mass of polyethylene “Novatech HB420R” (manufactured by Nippon Polyethylene Co., Ltd.) and 50 parts by mass of silicone acrylic rubber, a cylinder temperature of 210 ° C. and a screw It knead | mixed on the conditions of rotation speed 300rpm (primary kneading process).
15 parts by mass of the obtained kneaded product and 85 parts by mass of polycarbonate resin “Caliver 301-10” (manufactured by Sumika Stylon Polycarbonate) were kneaded under conditions of a cylinder temperature of 230 ° C. and a screw rotation speed of 300 rpm (secondary Kneading process).
Subsequent steps were performed in the same manner as in Example 1 to obtain a foam molded article [9].

[Reference Example 1]
A solid molded article [10] for reference was obtained in the same manner as in Production Example 1 of foam molded article, except that the formulation described in Table 1 was changed.

[Evaluation of molded body]
The molded body [1] to [10] according to the above examples, comparative examples, and reference examples were evaluated as follows. The results are shown in Table 1 below.

(1) Weight reduction rate The weight reduction rate is calculated according to the following formula (a), where P0 is the specific gravity of an unfoamed solid molded body of the resin material constituting the molded body, and P1 is the specific gravity of the foam molded body. Lightness was evaluated according to the evaluation criteria.
Formula (a): Weight reduction rate = ({P0−P1} / P0) × 100
-Evaluation criteria-
○: Weight reduction rate is 15% or more (pass)
Δ: Weight reduction rate is 10% or more (pass)
X: Lightening rate is less than 10% (failed)

(2) Surface roughness Using “VK-X100” manufactured by Keyence Corporation, an image obtained by observing the surface of the molded body was analyzed, the 10-point average roughness was calculated, and the surface shape of the mold was transferred according to the following evaluation criteria. Sex was evaluated.
-Evaluation criteria-
○: Surface roughness is 3.0 μm or less (pass)
Δ: Surface roughness is 4.0 μm or less (pass)
X: Surface roughness is 4.1 μm or more (failed)

  As is clear from the results in Table 1, it was confirmed that the foamed molded products according to Examples 1 to 5 had excellent lightness and excellent transferability of the surface shape of the mold.

10 Foam part 12 Skin layer 15 Air bubbles

Claims (8)

A method for producing a foamed molded article having a foam part having bubbles inside, and a skin layer containing an elastomer C formed so as to be integrated with the foam part and covering the surface thereof,
Amorphous thermoplastic resin A, a crystalline thermoplastic resin B having a melting point (Tm) higher than the glass transition point (Tg) of the amorphous thermoplastic resin A, and the crystalline thermoplastic resin Using elastomer C other than resin B,
(1) a primary kneading step of kneading the crystalline thermoplastic resin B and the elastomer C;
(2) a secondary kneading step of kneading the kneaded product obtained by the primary kneading step and the amorphous thermoplastic resin A;
(3) A method for producing a foamed molded article, comprising: a molding step of adding a foaming agent to the kneaded product obtained by the secondary kneading step and performing injection molding.   The method for producing a foam molded article according to claim 1, wherein the amorphous thermoplastic resin A is a styrene resin.   The foamed molded article according to claim 2, wherein the crystalline thermoplastic resin B has a melting point (Tm) higher by 50 ° C or more than the glass transition point (Tg) of the styrenic resin. Manufacturing method.   The method for producing a foamed molded article according to any one of claims 1 to 3, wherein the crystalline thermoplastic resin B is a polyester resin, a polyamide resin or a fluororesin.   The elastomer C is a copolymer of an alkyl methacrylate and / or an alkyl acrylate and an organosiloxane monomer, wherein the alkyl methacrylate and / or the alkyl acrylate is used in a monomer unit of 50% or more. It exists, The manufacturing method of the foaming molding in any one of Claims 1-4 characterized by the above-mentioned.   The method for producing a foam molded article according to any one of claims 1 to 5, wherein a kneading temperature in the primary kneading step is lower than a melting point (Tm) of the crystalline thermoplastic resin B. Used for injection molding for producing a foamed molded article having a foamed part having bubbles inside and a skin layer containing the elastomer C, which is integrated with the foamed part and covers the surface thereof. A method for producing a resin material for foam molded articles,
Amorphous thermoplastic resin A, a crystalline thermoplastic resin B having a melting point (Tm) higher than the glass transition point (Tg) of the amorphous thermoplastic resin A, and the crystalline thermoplastic resin Using elastomer C other than resin B,
(1) a primary kneading step of kneading the crystalline thermoplastic resin B and the elastomer C;
(2) A method for producing a resin material for a foam-molded product, which comprises a secondary kneading step of kneading the kneaded product obtained by the primary kneading step and the amorphous thermoplastic resin A. It has a foam part having bubbles inside, and a skin layer that is integrated with the foam part and covers the surface thereof, and has a thickness of 50 μm or more without bubbles, and the skin layer is an elastomer. A foamed molded article containing C,
The weight reduction rate is 10-50%,
The surface roughness Rz is 3 μm or less,
A foam molded article, wherein the elastomer C is present in the skin layer more than in the foam part.

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