JP5103866B2 - Foam molded body and method for producing the same - Google Patents

Description

  The present invention is a technology relating to a resin foam having excellent dimensional stability, high rigidity, and environmental friendliness. The resin foam is mainly used as a base material of a decorative material used for a building interior material such as a flooring material, a wall material, and a ceiling material, a fitting, furniture, and a surface material of home appliances. In addition, it may be used for structural purposes such as wood deck materials and benches.

  Conventionally, as decorative materials for various uses, natural veneer or decorative paper or decorative sheet with design printed on paper or synthetic resin sheet is bonded to woody base material such as plywood or fiberboard. Is often used. However, these decorative materials have problems such as warpage due to moisture absorption and release of wood base materials, worm-eatenness and corrosion, and are difficult to recycle. However, it is disposed of by landfill or incineration. In addition, so-called sick house syndrome caused by formalin derived from a thermosetting resin as a raw material, and environmental hormone substances eluted after landfill have become problems.

  In addition, as a base material other than wood, a synthetic resin base material such as a cushion floor base material in which a polyvinyl chloride resin is formed in a different shape, a molded member, or a foamed sheet is conventionally used. Polyvinyl chloride, however, cannot avoid the generation of toxic hydrochloric acid gas in the event of a fire, for example, has become a problem with environmental hormonal substances as additives, dioxins or hydrochloric acid generated during production or disposal There are problems that pollute the environment with gas and cause corrosion of molds and incineration facilities, etc., and are gradually being replaced by polyolefin-based materials.

Furthermore, attempts have been made to lower the coefficient of thermal expansion by filling with a filler, which has been put to practical use. However, although the thermal expansion coefficient of the resin is lowered, the above-described push-up problem has not been solved, and it has been necessary to absorb expansion and contraction of the base material by providing play in the shape of the base material and the joint portion. On the other hand, if the filler content is too large, the strength derived from the resin is lost, causing problems such as a significant decrease in impact resistance and poor usability due to an increase in specific gravity.
Moreover, in order to prevent push-up due to a decrease in the thermal expansion coefficient due to filler filling, it varies depending on the use conditions, but when applied to concrete or gypsum board, the bending elastic modulus of 1500 MPa or more as a generally used plate It is necessary to keep the coefficient of thermal expansion at a very low coefficient of 1 × 10 ⁻⁵ / ° C. or less in the case of the base material, and it is very difficult. I had to hold it down.

  On the other hand, when using a foam with a low expansion ratio in consideration of scratch resistance, the load on the human body, environment, and facilities, as seen in polyvinyl chloride, for the base material made of polyolefin material is greatly reduced. Problems such as expansion due to expansion when laid as a base material, and because it is a synthetic polymer material derived from petroleum, incineration causes an increase in carbon dioxide in the atmosphere and contributes to global warming There's a problem. Efforts to reduce carbon dioxide emissions by using plant-derived resources in response to global warming are advancing. This is because when fossil resources in the ground are burned, the carbon contained in the fossil resources is released into the atmosphere as carbon dioxide, but if it is a plant-derived resource, the carbon dioxide captured by the plant from the atmosphere It is promoted based on the consideration that it has little influence on global warming.

Conventional woody substrates are excellent in this respect, and although there are soil contamination and problems with the human body, the impact on global warming is lower than that of polyolefin-based materials. Under these circumstances, plant-derived resin raw materials have been demanded, and various aliphatic polyesters including polylactic acid have been synthesized from plant-derived raw materials.

The polylactic acid resin is a homopolymer of either L-lactic acid or D-lactic acid, a random copolymer of L-lactic acid and D-lactic acid, a block copolymer of L-lactic acid and D-lactic acid, or a mixture of two or more thereof. The enantiomeric ratio of lactic acid greatly affects the crystallization ability of polylactic acid resin. Therefore, it is used while appropriately adjusting in light of the required quality such as heat resistance and impact resistance of the target molded product.
Also, for aliphatic polyesters other than polylactic acid, many resins are currently synthesized from petroleum-derived raw materials, but attempts to synthesize these from plant-derived resources continue, and plant-derived resources are used. Development is also in progress from a viewpoint.
Aliphatic polyesters are aliphatic polyesters that can be produced by various combinations of aliphatic hydroxycarboxylic acids, aliphatic dihydric alcohols, and aliphatic dibasic acids. In addition to polylactic acid, polyglycolic acid, polyethylene oxalate, polybutylene Examples thereof include oxalate, polycaprolactone, polyneopentyl glycol oxalate, polyethylene succinate, polybutylene succinate, polyhydroxybutyric acid and the like.

Aliphatic polyester has a lower melt viscosity compared to resins such as polystyrene, polyvinyl chloride, and polyolefins that have been used for conventional foam molding, causing foam breakage during extrusion foam molding, and sufficient foaming ratio cannot be obtained. And had various drawbacks such as severe restrictions on molding conditions. Therefore, in order to be put to practical use, it is necessary to improve the melt tension, develop the strain hardening property at the time of measuring the extension viscosity, and improve the crystallization speed.
In general, it is considered effective to add a high polymerization degree polymer or to use a polymer having a long chain branch in order to develop strain hardening. In the production of a polymer having a high degree of polymerization, polymerization takes a long time, and coloring or decomposition due to thermal history is likely to occur. On the other hand, as a method for producing branched polylactic acid, a method of adding a polyfunctional initiator at the time of polymerization, or a method of causing cross-linking by melt-kneading with a peroxide or a reactive compound in a post-process, Etc. are known. However, in practice, it is difficult to control a homogeneous branching or cross-linking structure, and as a result, a high-quality foam has not been stably formed, for example, a retention portion due to gel or quality unevenness.
JP 2003-184290 A JP-T-2004-538178 JP 2004-292499 A JP 2004-67894 A JP 2004-352750 A

By the way, the Celca method is very useful as a method for producing a foamed molded article having a skin layer. However, since the molten resin is strongly pressed against the surface of the sliding sizing die by the pressure of the foaming gas, the sliding resistance in the sliding sizing die When the rigidity of the skin layer in the sliding sizing die, particularly in the vicinity of the entrance, or the melt tension of the molten resin is low, the resin melt cannot follow the take-up and deformation or breakage occurs. Accordingly, there is a problem that a resin having low rigidity in a solid state such as an elastomer or a resin highly filled with a filler cannot be molded by a cell or a method. In addition, even when trying to obtain a foamed molded article having a high foaming ratio, there is a problem that the resin loses the tensile resistance in the sliding sizing die and breaks, so that it cannot be molded.

  An object of the present invention is to mold a foamed molded article having a skin layer such as a soft resin, a filler high-filling resin, and a high expansion ratio molding that could not be molded by the conventional Selca method. In addition, after molding, when the sheet-like base material is integrated without being peeled off, it is bonded by bonding by heat fusion of what was conventionally combined with a technique such as laminating or wrapping using an adhesive. The goal is to improve recyclability and reduce environmental impact without using any chemicals.

Invention according to claim 1, polylactic acid, comprising a thermally swellable microcapsule and fillers, in the foaming molded article having a skin layer, a thermoplastic resin melt containing at least polylactic acid, the heat-swellable microcapsule and filler When passing through a sliding sizing die, a sheet-like base material is passed between a thermoplastic resin melt and a sliding sizing die. When the thermoplastic resin melt is passed through the sliding sizing die, the sheet-like substrate is passed between the thermoplastic resin melt and the sliding sizing die, thereby reducing the sliding resistance of the thermoplastic resin melt and the sliding sizing die. In addition to the reduction, it is possible to cope with various moldings by giving the entire resin strength during take-up. A skin layer can be formed by quickly cooling the surface of a thermoplastic resin melt in which a foaming agent extruded from a mold is appropriately dispersed, and a sheet-like substrate can be used to form a resin such as breakage or deformation. Since the factors that did not exist can be eliminated, it is possible to easily produce a foamed molded article of a soft material and a highly filled material that could not be molded by an extrusion method that can be continuously molded. In addition, a foamed molded article having a high expansion ratio can be produced without causing breakage or deformation of the thermoplastic resin melt.

  The invention according to claim 2 is a foamed molded article obtained by foaming and molding a thermoplastic resin melt using the method for producing a foamed molded article according to claim 1.

The invention according to claim 1 is a foam molded article including at least a thermoplastic resin, a thermally swellable microcapsule, and a filler, and having a skin layer, and a sheet when passing the thermoplastic resin melt through a sliding sizing die. It is a manufacturing method of the foaming molding characterized by passing a glass-like base material between a thermoplastic resin melt and a sliding sizing die. When the thermoplastic resin melt is passed through the sliding sizing die, the sheet-like substrate is passed between the thermoplastic resin melt and the sliding sizing die, thereby reducing the sliding resistance of the thermoplastic resin melt and the sliding sizing die. In addition to the reduction, it is possible to cope with various moldings by giving the entire resin strength during take-up. A skin layer can be formed by quickly cooling the surface of a thermoplastic resin melt in which a foaming agent extruded from a mold is appropriately dispersed, and a sheet-like substrate can be used to form a resin such as breakage or deformation. Since the factors that did not exist can be eliminated, it is possible to easily produce a foamed molded article of a soft material and a highly filled material that could not be molded by an extrusion method that can be continuously molded. In addition, a foamed molded article having a high expansion ratio can be produced without causing breakage or deformation of the thermoplastic resin melt.

The invention according to claim 2 is a foamed molded article obtained by foaming and molding a thermoplastic resin melt using the method for producing a foamed molded article according to claim 1. It is possible to obtain an inexpensive foamed molded product that is more environmentally friendly and efficient than the conventional foamed molded product.

  The present invention is described in detail below.

  The thermoplastic resin used in the present invention is not particularly limited, but polyolefin resins such as polyethylene and polypropylene, polystyrene resins, polyvinyl chloride resins, polymethyl methacrylate resins, aliphatic polyester resins, polyethylene terephthalate. It is possible to appropriately select from resin, polyamide resin, and the like. These may be used alone, or may be used as a blend or a copolymer.

  In addition, a high melt tension is usually desirable for improving foamability, but in the molding method of the present invention, heat-swellable microcapsules are used as a foaming agent, so that even a low melt tension resin can be foamed well. is there. Even when high foaming exceeding 3 times is used, a resin suitable for foaming such as polystyrene or polyvinyl chloride is usually selected, or a resin of a grade introduced with long chain branching by electron beam crosslinking is used. It is desirable to adjust the melt tension as necessary by a known method such as control of the molecular weight distribution and blend of a fluorine-based additive for increasing the melt tension. However, in the present invention, a resin having a low melt tension is not particularly problematic. It can be used.

Therefore, in the present invention, a high-magnification foamed molded product of a mixture of homopolypropylene and filler having a relatively high melt flow rate, which has low environmental burden and excellent physical properties as a base material but has been difficult to form by conventional methods, Although the load is low, the melt viscosity is low, and foam molding of an aliphatic polyester resin made of a plant-derived raw material such as polylactic acid, which requires secondary treatment such as cross-linking for foam molding, is possible. It becomes possible.

If necessary, heat stabilizers, acid neutralizers, UV absorbers, light stabilizers, bubble regulators, carboxyl end-capping agents, colorants such as pigments and dyes, antistatic agents, lubricants, nucleating agents A flame retardant, an antiblocking agent, a gloss adjusting agent, and the like can also be added. Among these additives, hindered phenols, sulfurs, phosphoruss, etc. as heat stabilizers, stearic acid metal salts, hydrotalcite, etc. as acid neutralizers, benzotriazoles, benzoates as ultraviolet absorbers, etc. , Benzophenone, triazine, etc., hindered amines as light stabilizers, polytetrafluoroethylene modified with acrylic resin as bubble regulators, carbodiimide, glycidyl ester, etc. as flame retardants, carboxyl group terminal blockers As halogen-based flame retardants, phosphorus-based flame retardants, chlorine-based flame retardants, etc., lubricants as hydrocarbon-based lubricants, fatty acids, higher alcohols, fatty acid amides, metal soaps, esters, fluorines, etc. As pigments such as carboxylic acid metal salt, sorbitol, phosphate ester metal salt, etc. There are pearl pigments such as condensed azo, insoluble azo, quinacridone, isoindoline, anthraquinone, imidazolone, cobalt, phthalocyanine, carbon, titanium oxide, iron oxide, mica, etc., and these additives are generally used in any combination Is.

The filler used in the present invention can be appropriately selected from known inorganic fillers and organic fillers.
Specific examples of the inorganic filler include talc, non-swellable mica, swellable mica, swollen mica subjected to ion exchange, calcium carbonate, bentonite, organically modified montmorillonite, magnesium hydroxide, wollastonite, silica, alumina, oxidation Magnesium, calcium oxide, calcium silicate, sodium aluminate, calcium aluminate, sodium aluminosilicate, magnesium silicate, glass balloon, carbon black, zinc oxide, antimony trioxide, zeolite, hydrotalcite, potassium titanate, boron nitride, Examples thereof include graphite, glass fiber, and carbon fiber.

Specific examples of organic fillers include cotton fiber, hemp fiber, kenaf fiber, hemp fiber, jute fiber, banana fiber, coconut fiber, cellulose fiber, paper powder, wood powder, bamboo powder, cellulose powder, rice husk powder, fruit shell powder. , Protein, starch and the like.
These fillers may be coated with a thermoplastic resin such as an ethylene / vinyl acetate copolymer or a thermosetting resin such as an epoxy resin to improve adhesion with the resin, such as aminosilane or epoxysilane. You may process by a well-known method with a coupling agent etc. Moreover, according to a use and the objective, you may use single and may mix multiple types.

As the selection of the filler in the present invention, the thermal expansion coefficient reducing effect is high, and there is also a nucleating effect. Plates such as talc, mica, organically modified montmorillonite, scale-like filler, relatively low specific gravity, and cutting of foam molded products More preferably, it is selected from fibrous organic fillers such as kenaf fiber and wood flour, which have a great effect on the properties and nailing properties.
The blending ratio of the filler depends on the use of the foamed molded product and the type of filler, but is preferably 10% by weight or more and 70% by weight or less, more preferably 20% by weight or more and 50% by weight or less, based on the total.

The heat-swellable microcapsules in the present invention include those obtained by wrapping a hydrocarbon foaming agent such as isobutane, isopentane, isohexane, or isooctane with a polymer having a large gas barrier property such as a vinylidene chloride / acrylonitrile copolymer. In particular, since heat resistance is required for heat-swellable microcapsules to be used in extrusion molding, heat-swellable microcapsules having a polymer composed of a nitrile monomer and a monomer having a carboxyl group as an outer shell polymer, Furthermore, a heat-swellable microcapsule having a polymer composed of a nitrile monomer, a monomer having a carboxyl group, a monomer having an amide group, a monomer having a cyclic structure in the side chain as an outer shell polymer in JP WO2004 / 058910, It is desirable to use heat-swellable microcapsules with high heat resistance.
By using heat-swellable microcapsules under appropriate conditions, it is possible to produce foamed molded products with high mechanical strength of closed cells even when using resins with low melt viscosity or resins that are generally not suitable for foaming with strain rate softening properties. It becomes possible to make.

The method of kneading the filler and the thermoplastic resin is not particularly limited. Generally, a method of kneading with a Henschel mixer, cooling and pulverizing and pelletizing with a pelletizer, or a method of mixing and pelletizing with a twin screw extrusion kneader are common.
In addition, a known foaming technique and equipment can be used as they are for the extrusion technique and equipment. As the extruder, both a single-screw extruder and a twin-screw extruder can be used. In the twin-screw extruder, any of the same direction, different directions, conical, and parallel can be used. Similar to the known foaming technique, it is not desirable in terms of quality and stability that the heat-swellable microcapsules swell in the extruder while maintaining a sufficient resin pressure in the vicinity of the exit of the extruder.

The foam molding method according to the present invention is a molding method by an extrusion method capable of continuous molding, and any method can be used as long as a sliding sizing die can be used. For example, application to foamed sheet molding using a T-die or a deformed shape is assumed.

  FIG. 1 shows a schematic view of the method for producing a foamed molded product of the present invention. In the drawings of the present invention, both the thermoplastic resin melt and the foamed molded product are denoted by reference numeral 1. The thermoplastic resin melt 1 is extruded from the mold 2 and then passed through a sliding sizing die together with the sheet-like substrate.

  The mold 2 only needs to have a mechanism for continuously extruding the thermoplastic resin melt, and examples thereof include a T die and a dying die. Since the mold 2 is close to the sliding sizing die 3 and positioning is also important, a contact surface is often provided, and heat insulation becomes important. At the same time, existing methods such as oil circulation can be used in addition to the heater. It is desirable to use and maintain the temperature of the mold.

On the other hand, the existing design method is also used for the sliding sizing die 3. Generally, a material having high thermal conductivity such as brass or aluminum is used, and a flow path for circulating a coolant such as water is provided. This flow path is provided at a position close to the flow surface of the resin by appropriately adjusting the dimensions according to the Reynolds number or the like so as to be turbulent in order to enhance the cooling effect. Further, the sliding sizing die 3 can be disposed in the water, and in this case, a vacuum slit or the like for sucking out the water entering the sliding sizing die 3 can be provided.

  Regarding the length of the sliding sizing die 3, the purpose can be achieved with a relatively short length for the formation of the target skin layer. In addition to this, if the subsequent cooling method is a cooling method in which the shape changes due to the foaming pressure, such as when a chill roll is used, a sufficient length is required so that the shape does not change due to the foaming pressure. .

  It is desirable that the thermoplastic resin melt 1 extruded from the mold 2 is cooled to a desired shape while applying sufficient pressure until foaming by the foaming gas stops. The cooling method can be selected from sliding sizing dies, chill rolls, cooling using a metal belt, etc., except for the initial cooling at the die exit. It is necessary to use it. This is because, in the case of the chill roll method and the metal belt method, the roll diameter is inevitably increased to overcome the foaming pressure, and the air gap is increased, so that foaming of the surface proceeds and a good skin layer cannot be obtained. It is.

Also, the resin outlet shape of the mold can be arbitrarily designed in accordance with the melt properties of the extruded resin. There is a tendency that a foam molded article having a good skin layer can be obtained by a hollow shape often used in the SELKA method or a method of extruding in a strand shape. In sheet forming using a T die, a sheet of about 2 mm to 10 mm can be formed by providing a torpedo to the die exit, extruding in two layers, and joining them in sizing. In FIG. 1, a torpedo 5 is provided at the mold outlet. In sheet molding of 3 mm or less, a skin layer can be formed on both sides even when extrusion is performed with one layer without using a torpedo.

  The opening at the entrance of the sliding sizing die is preferably the final product shape or slightly larger than this, and is preferably slightly larger than the outer periphery of the resin outlet of the die. If it is smaller than the outer periphery of the resin outlet of the die, the resin smoothly slips into the sizing die and the take-up resistance increases, or the resin stably enters the sliding sizing die. Further, if the entrance of the sliding sizing die is too large, a problem that a good skin layer is not formed occurs. It is also possible to provide the skin layer only on a part of the foamed molded article by using the so-called partial cellca method by appropriately adjusting the size and arrangement of the openings of the mold and the sliding sizing die.

About the space | interval of the metal mold | die 2 and the sliding sizing die 3, an appropriate range changes with molding conditions. What is important is that the skin layer is formed before the surface layer is foamed, which means that the allowable range of the gap between the die and the sliding sizing die varies depending on the molding speed. It is important to design the time from exiting the mold until the resin enters the sliding sizing die within 0.5 seconds, more preferably within 0.1 seconds. When the time longer than this elapses, the surface layer is foamed and a good skin layer is not formed.

Further, since resistance is applied to the sliding sizing die, the sliding sizing itself may move in the downstream direction. In order to prevent this, the sliding sizing die needs to be mechanically held with a strength sufficient to withstand pressure.

  Since a relatively large take-up resistance is applied in the sliding sizing die due to the pressure of the foaming gas, a take-up mechanism is required after the sliding sizing die, and the nip roll 4 is provided. If the sheet is formed by a T-die, a driving nip roll may be used. However, if the take-up resistance is high, it is necessary to arrange a plurality of drive-type nip rolls or use a caterpillar take-up machine.

  On the other hand, after the skin layer is formed by the sliding sizing die, a cooling method using a chill roll or a metal belt can be appropriately selected. Cooling with a sliding sizing die can be performed while applying pressure to the target shape, and has the advantage of being able to cool to various shapes, but has a drawback that a large force is required for taking up because of frictional resistance. In addition, cooling with a metal belt can be expected to have a pulling force without pressure while applying pressure, but the accuracy is inferior to a sliding sizing die. Although cooling with a chill roll can be applied mainly to cooling of a sheet-like molded body, there are problems such as inability to always apply pressure, narrow contact area and poor cooling efficiency. Therefore, it is necessary to select a cooling method as appropriate depending on the target shape and operating state.

  In the present invention, the sheet-like substrate 6 is passed through the sliding sizing die simultaneously with the thermoplastic melt. About the sheet-like base material used, both a material and a shape can be selected as appropriate. Specifically, a metal foil such as an aluminum foil, a resin film such as a biaxially stretched polyethylene terephthalate film or a cast homopolypropylene film, and paper can be used. The sheet-like substrate is wound up, for example, in a roll shape, and is continuously supplied when the thermoplastic resin melt passes through the sliding sizing die.

  When a resin film, paper, or the like is used, the thickness of the skin layer is reduced, and the strength is decreased due to fine foaming. Therefore, when emphasizing the thickness of the skin layer and the expansion ratio, it is preferable to quench the surface of the thermoplastic resin by using a metal foil as the sheet-like substrate. A good skin layer is formed by using a sheet-like substrate as a metal foil. However, when a resin sheet having a thickness of about 0.5 mm or less is used, the quality of the skin layer is not greatly deteriorated. When importance is attached to the functionality of the sheet-like base material, some quality of the skin layer is used. Even if there is a decrease, the object of the present invention can be sufficiently achieved.

  If the resin is solidified to some extent in the sliding sizing die and the foamed molded body has a strength that can withstand the frictional resistance in the sliding sizing die, then the sheet-like substrate may be peeled off at an arbitrary timing. For example, when there are a plurality of sliding sizing dies, an intermediate portion between the sliding sizing die and the sliding sizing die may be used, and an off-line peeling step may be provided after the sliding sizing die. Moreover, when the adhesiveness of a sheet-like base material and a thermoplastic resin melt is good, you may perform easy peeling processes, such as a release coat.

  In addition, when a material of the same type as the extruded resin is used for the sheet-like base material, the function of the sheet-like base material that is bonded and combined by the pressure to the sliding sizing die by the foaming gas and the heat of the molten resin is directly foamed. It can be applied to the molded body. As the function, for example, various known functions such as hard coat, adhesion imparting, antistatic property, designability imparting, weatherability imparting and the like can be imparted. Conversely, it is possible to use a film that is not heat-sealed as it is as a protective film.

  In the case of using a sheet-like base material made of a material having poor heat conductivity such as resin, there is a concern that the formation of the skin layer may be delayed. Therefore, the thickness of the sheet-like base material is desirably 0.5 mm or less. However, this is not the case when the sheet-like base material is not charged over the entire surface of the molded body and a reduction in thickness or physical properties of the skin layer of the foam molded body is acceptable.

An explanatory sectional view of the foamed molded article of the present invention is shown in FIG. The foamed molded body made of the thermoplastic resin of the present invention has a smooth skin layer 11 on the surface, and the foamed body has a foamed layer 12 inside.

In the present invention, foam molding of a resin that is not suitable for the Celca method, such as a foam molded body having a high expansion ratio, is also possible. As a result, since the frictional resistance is applied by the foaming gas pressure when entering the sliding sizing die, which is a drawback of the SELKA method, it is possible to solve the difficulty that a foam with a high foaming ratio cannot be molded. Also, by controlling the resin of the foamed molded product, the resin of the sheet base material, and the molding conditions, the sheet base material can be bonded simultaneously with the molding, and there are many advantages in terms of cost and environment.

Examples of the present invention and comparative examples are shown below. Example 1 is a reference example.
The materials and equipment used were as follows. The blending ratio is expressed in weight% where the total amount is 100. However, the foaming agent is externally added. For example, when 3% by weight of the foaming agent is added, the total amount is 103% by weight. The filler used was adjusted to a moisture content of 2% by weight or less.

<Materials used>
Homopolypropylene (Prime Polymer Prime Polypro E100GV)
Acid-modified polypropylene (Sanyo Kasei Umex 1001)
Polylactic acid (Mitsui Chemicals Lacia H440)
Wood flour (Shimada Shokai Cellulosin 100M)
Talc (Takehara Chemical Hightron)
Carboxyl group terminal blocker (Nisshinbo Carbodilite LA-1)
Heat-swellable microcapsules (Matsumoto Yushi Seiyaku Matsumoto Microsphere F230)
ADCA foaming agent master batch (Daiichi Seika Kogyo Fine Cell Master PO551K)

<Devices used>
Co-directional twin-screw extruder (Nippon Steel Works TEX65)
Single screw extruder (Ikegai Iron Works FS-65 L / D = 36)
Mold 1 (150mm width 5mm thickness plate shape Selka foam molding mold)
Mold 2 (150mm width 5mm thickness plate shape sheet cell foaming mold)
Dehumidifying dryer (Kawata Challenger II)

<Device conditions>
Same direction twin screw extruder 180 ° C setting 150rpm 100kg / h
Single screw extruder conditions 150 ° C setting mold temperature 170 ° C setting sizing temperature 30 ° C setting

(1) Preparation of Compound 1 Compound 1 was prepared by kneading 10 parts by weight of acid-modified polypropylene, 50 parts by weight of homopolypropylene, 30 parts by weight of wood flour, and 10 parts by weight of talc with a twin screw extruder in the same direction. did.
(2) Production of Foam Molded Body The above-mentioned compound 1: 100 parts by weight, heat-swellable microcapsules: 4 parts by weight were extruded using a mold 2 with a single-screw extruder using a sheet cell method, and a foaming ratio of 3.0. A foamed molded article of Example 1 having a doubled flexural modulus of 1600 MPa was prepared.

(1) Preparation of Compound 2 Compound 2 was prepared by kneading 40 parts by weight of acid-modified low-density polypropylene, 50 parts by weight of wood flour, and 10 parts by weight of talc with a twin screw extruder in the same direction.
(2) Preparation of foamed molded product The above compound 2: 70 parts by weight, polylactic acid 2: 29 parts by weight, heat-swellable microcapsules: 3 parts by weight, carboxyl group terminal blocker: 1 part by weight in a single screw extruder The mold 2 was extruded using the sheet selka method to produce a foamed molded article of Example 2 having a foaming ratio of 2.6 times and a flexural modulus of 2000 MPa.

<Comparative Example 1>
(1) Compound Compound 1 prepared in Example 1 was used.
(2) Production of foam molded body The above compound 1: 100 parts by weight, ADCA foaming agent masterbatch: 6 parts by weight was extruded using a mold 2 with a single screw extruder using a sheet selka method, and a foaming ratio of 2.4. A foamed molded article of Comparative Example 1 having a doubled flexural modulus of 1800 MPa was prepared. However, the foamed molded product had a rough surface due to outgassing due to open cells in the foamed cells.

<Comparative example 2>
(1) Preparation of Compound 4 Compound 4 was prepared by kneading 40 parts by weight of acid-modified low-density polypropylene, 50 parts by weight of wood flour, and 10 parts by weight of talc with a twin screw extruder in the same direction.
(2) Preparation of Foam Molded Body The above compound 4: 70 parts by weight, polylactic acid 2: 29 parts by weight, ADCA foaming agent master batch: 4 parts by weight, carboxyl group terminal blocker: 1 part by weight in a single screw extruder. The mold 2 was extruded using the sheet selka method to prepare a foamed molded article of Comparative Example 2 having a foaming ratio of 1.6 times and a flexural modulus of 2400 MPa. However, the foamed molded product had a rough surface due to outgassing due to open cells in the foamed cells.

<Comparative Example 3>
(1) Compound Compound 1 prepared in Example 1 was used.
(2) Preparation of foamed molded body The above compound 1: 100 parts by weight, heat-swellable microcapsules: 4 parts by weight were extruded using a mold 1 with a single screw extruder using the selka method, but a sliding sizing die Due to the internal resistance, the foamed molded article was cut and could not be molded.

<Comparative example 4>
(1) Compound Compound 1 prepared in Example 1 was used.
(2) Preparation of foamed molded body The above-mentioned compound 1: 100 parts by weight, ADCA foaming agent masterbatch: 2 parts by weight were extruded using a mold 1 with a single screw extruder using the Celca method, and the foaming ratio was 1.5. A foamed molded article of Comparative Example 4 having a doubled flexural modulus of 2000 MPa was prepared.

Table 1 shows the results of various evaluations of the foam molded articles of Examples 1 and 2 and Comparative Examples 1 to 4. The measuring method of the flexural modulus was measured according to JIS K7171. Moreover, the measuring method of a foaming ratio measured the density of the foaming molding and the density of the foaming molding which did not put a foaming agent, using Shiro Sangyo Electronic Densitometer SMD-200S. Density / calculated from the density of the molded foam. Moreover, the measuring method of the coefficient of thermal expansion was measured according to JIS K7197.
For the evaluation of closed cells, a sample cut out to a thickness of 100 μm with a microtome is observed with an SEM, and any 30 bubbles are taken. If there are 3 open bubbles or less, ◎ If 4 or more and 10 or less, ○ When the number was 11 or more and 25 or less, the evaluation was Δ, and when the number was 26 or more, the evaluation was ×.

  As shown in Table 1, Examples 1 to 2 showed good foamability and push-up resistance. From Comparative Example 1 and Comparative Example 2, it was confirmed that the thermally expandable microcapsules improved foamability and physical properties. Moreover, it was confirmed that the push-up resistance is improved by foaming from Comparative Example 4. Further, it was confirmed that the sheet celler method was superior when molding at a higher expansion ratio than Comparative Example 3.

  According to the present invention, it has become possible to produce a more environmentally friendly foam molded body at a lower cost and more efficiently than conventional foam molded bodies.

It is the schematic of an example of the manufacturing method of the foaming molding of this invention. It is sectional drawing of an example of the foaming molding of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thermoplastic resin melt / foaming molding 11 Skin layer 12 Foaming layer 2 Mold 3 Sliding sizing die 4 Nip roll 5 Torpedo 6 Sheet-like base material

Claims (2)

In a foamed molded article containing polylactic acid , heat-swellable microcapsules and filler, and having a skin layer, when passing a thermoplastic resin melt containing at least polylactic acid, heat-swellable microcapsules and filler through a sliding sizing die, A method for producing a foamed molded article, comprising passing a sheet-like substrate between a thermoplastic resin melt and a sliding sizing die.   A foamed molded article obtained by foaming and molding a thermoplastic resin melt using the method for producing a foamed molded article according to claim 1.