JP2006175825A - Composite molded body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composite molded body which is excellent in a foaming property, and also in soft feeling and heat resistance. <P>SOLUTION: The composite molded body is made by carrying out one piece molding of a foaming layer to a polyolefin-based composite resin layer. A composition for a foaming layer which composes the foaming layer comprises: (a) a hydrogenated product of a block copolymer having an aromatic vinyl compound and a conjugated diene compound; (b) a propylene-based polymer; (c) a softening material for rubber, and (d) a propylene-based polymer mixture comprising a crystalline propylene polymer and an amorphous copolymer comprising propylene and ethylene. (A) The type A hardness of the composition for the foaming layer is not more than 80, the surface hardness (ASKER C) of the foaming layer is not more than 75, (B) the foaming magnification of the foaming layer is at least 1.2, (C) the melt extensibility of the composition for the foaming layer is at least 80 m/min at 170-190°C, and (D) the temperature at the time of 0.1 mm deformation of the TMA measurement value of the composition for the foaming layer is at the lowest 100°C, and the temperature at the time of 0.5 mm deformation is at the lowest 120°C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a composite molded body in which a foamed layer is integrally formed with a polyolefin-based composite resin layer.

Currently, urethane foam is widely used in members that require cushioning properties such as automobile interior materials, home appliances, and furniture.
In recent years, many foams produced by injection molding using a thermoplastic resin have been reported from the viewpoints of recyclability and productivity. Among them, as a method excellent in productivity and appearance, there is a method of foaming by opening a mold after injection filling with a molding material.

  However, the expansion ratio by this method cannot be increased so much. Therefore, for example, in order to obtain a smooth surface and an overall soft feeling (soft feeling with low rebound resilience), as disclosed in Patent Document 1, a method for producing a foam mainly using an elastomer is used. ing. According to the production method of Patent Document 1, not only excellent surface appearance and smoothness without generation of silver can be obtained, but also relatively excellent foam cell uniformity can be obtained.

  However, according to the manufacturing method of Patent Document 1, a low-hardness elastomer is used. Therefore, for example, the present situation is that the target has not yet been achieved for the excellent heat resistance required for a part of automobile interior materials.

Japanese Patent Laid-Open No. 6-218741

  The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a composite molded article having excellent foaming characteristics and excellent softness and heat resistance.

The present invention is a composite molded body formed by integrally forming a foam layer by foam injection molding a foam layer composition on a polyolefin-based composite resin layer placed or injection molded in a mold,
The foam layer composition is
(A) a hydrogenated block copolymer having a weight average molecular weight of 200,000 or less having an aromatic vinyl compound block and a conjugated diene compound block;
(B) a propylene-based polymer;
(C) a softening material for rubber;
(D) containing 30 to 70% by weight of a crystalline propylene polymer, and the balance containing each component of a propylene-based polymer mixture made of an amorphous copolymer containing propylene and ethylene;
The foam layer composition or the foam layer is
(I) The foam layer composition according to JIS-K6253 has a type A hardness of 80 or less, and the surface hardness of the foam layer according to Asker C is 75 or less.
(B) The foaming ratio of the foamed layer is 1.2 times or more,
(C) The melt ductility of the composition for a foam layer is 80 m / min or more at 170 to 190 ° C.,
(D) In the TMA measurement value of the foamed layer composition in accordance with JIS-K7196, each property has a temperature at 0.1 mm deformation of 100 ° C. or higher and a temperature at 0.5 mm deformation of 120 ° C. or higher. It is in the composite molded object characterized by having (Claim 1).

The composite molded body of the present invention is obtained by improving the composition of the foam layer composition and injection molding the foam layer composition containing the components (a) to (d). It was manufactured to have each of the properties of d).
That is, the foamed layer composition contains a hydrogenated block copolymer having an aromatic vinyl compound block and a conjugated diene compound block having a weight average molecular weight of 200,000 or less as the component (a).
In this component (a), the aromatic vinyl compound block constitutes a hard segment (hard phase) which is a molecular constraint component for preventing plastic deformation, and the conjugated diene compound block is a flexible component having rubber elasticity. Constituting a soft segment (soft phase).

Moreover, as a structure of the said block copolymer, it can be set as a diblock copolymer or a triblock copolymer, for example. More preferably, it can be a triblock copolymer having rubber elasticity.
The hydrogenated product of the block copolymer may be obtained by partially or completely hydrogenating double bonds in the conjugated diene compound constituting the conjugated diene compound block. The hydrogenation rate of the conjugated diene compound block is preferably 50% or more, particularly 80% or more. When this hydrogenation rate is less than 50%, the weather resistance and heat resistance of the foamed layer in the composite molded body tend to be inferior.

Examples of the aromatic vinyl compound constituting the aromatic vinyl compound block include styrene, α-methylstyrene, o-, m-, p-methylstyrene, 1,3-dimethylstyrene, vinylnaphthalene, and vinylanthracene. Among them, styrene is preferable.
Examples of the conjugated diene compound constituting the conjugated diene compound block include butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, etc., among which butadiene, isoprene or both ( A mixture of butadiene / isoprene is preferable.

The content ratio of the aromatic vinyl compound block to the conjugated diene compound block is such that the content of the aromatic vinyl compound block is 5 to 50% by weight, and the remainder is the conjugated diene compound block. . More preferably, the content of the aromatic vinyl compound block can be 10 to 40% by weight, and the balance can be the conjugated diene compound block.
When the content of the aromatic vinyl compound block is less than 5% by weight, the mechanical strength and heat resistance of the foamed layer in the composite molded body tend to be inferior. On the other hand, when the content of the aromatic vinyl compound block exceeds 50% by weight, the flexibility of the foamed layer in the composite molded body may be lost.

The weight average molecular weight of the hydrogenated product of the block copolymer is shown as a weight average molecular weight in terms of polystyrene measured by gel permeation chromatography. Moreover, the weight average molecular weight of the hydrogenated product of the block copolymer can be more preferably 5 to 150,000.
When the weight average molecular weight is less than 50,000, the mechanical strength of the foam layer in the composite molded body tends to be inferior. On the other hand, when this weight average molecular weight exceeds 150,000, the melt ductility of the foamed layer in the composite molded article is lowered and the foamability tends to be inferior.

Moreover, the said block copolymer can be obtained by performing block polymerization in an inert solvent using a lithium catalyst etc. by the method described in Japanese Patent Publication No.40-23798, for example.
Further, the hydrogenation treatment of the block copolymer is described in, for example, JP-B-42-8704, JP-B-43-6636, JP-A-59-133203, or JP-A-60-79005. Can be carried out in an inert solvent in the presence of a hydrogenation catalyst.

Examples of commercially available block copolymers include “KRATON-G” (Clayton Polymer Co., Ltd.), “Septon” (Kuraray Co., Ltd.), and “Tuftec” (Asahi Kasei Co., Ltd.).
The block copolymer can also be obtained by polymerizing an elastomeric block from styrene or a derivative thereof and coupling it with a coupling agent. The block copolymer can also be obtained by polymerizing an elastomeric block using a dilithium compound as an initiator and then successively polymerizing styrene or a derivative thereof.

Moreover, the said composition for foamed layers contains a propylene polymer as said (b) component.
Examples of the propylene polymer include polypropylene and a propylene-ethylene copolymer (random polypropylene or block polypropylene).
The range of MFR (melt flowability, melt flow rate) of the propylene-based polymer can be 2 to 100 g / 10 minutes. The propylene-based polymer preferably has an isotactic propylene block, and its melting point is preferably 150 ° C. or higher.
Moreover, the compounding quantity of the propylene-type polymer as a (b) component with respect to 100 weight part of hydrogenated products of the block copolymer as the said (a) component can be 30-200 weight part.

Moreover, the said composition for foamed layers contains the softening material for rubber | gum as said (c) component.
Examples of the rubber softener include paraffinic, naphthenic or aromatic mineral oil hydrocarbons, or synthetic resin hydrocarbons such as polybutene or polybutadiene. Moreover, these hydrocarbons preferably have a weight average molecular weight of 300 to 2000, more preferably 500 to 1500. In addition, the hydrocarbon preferably has a kinematic viscosity at 40 ° C. of 20 to 800 cst, and more preferably 50 to 600 cst. In addition, the hydrocarbon preferably has a pour point of −40 to 0 ° C., and more preferably −30 to 0 ° C. The hydrocarbon preferably has a flash point of 200 to 400 ° C, and more preferably 250 to 350 ° C.

The foam layer composition contains 30 to 70% by weight of a propylene-containing crystalline propylene polymer as the component (d), with the balance containing propylene and ethylene. A propylene polymer mixture comprising:
In addition to propylene, the crystalline propylene polymer contains, for example, ethylene, 1-butene, 3-methyl-1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene and the like. Can be.

The propylene content in the crystalline propylene polymer is preferably 90% by weight or more, and more preferably 95% by weight or more. The stereoregularity of propylene preferably has an isotactic index of 90% or more.
The amorphous copolymer preferably contains an α-olefin having 2 to 8 carbon atoms in addition to propylene and ethylene. Examples of the α-olefin having 2 to 8 carbon atoms include 1-butene, 3-methyl-1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene and 1-octene.
In addition, an alpha olefin means what has a double bond in the alpha position (between the endmost carbon and the next carbon) among olefinic hydrocarbons.

Moreover, the said composition for foamed layers contains the foaming agent besides the said (a)-(d) component.
The foaming agent can be a foaming gas that is dissolved in the composition for the foamed layer, and can also be a foaming agent component that generates gas during foam molding. Also, the foaming gas and the foaming agent component can be used simultaneously.
Moreover, as foaming gas dissolved in the composition for foamed layers, it can be used regardless of an organic type and an inorganic type, For example, it is preferable to use nitrogen and carbon dioxide which are rich in safety on manufacture.

  Moreover, as a foaming agent component which generate | occur | produces gas at the time of foam molding, it can be used regardless of an inorganic component and an organic component. Specifically, as a foaming agent component, an azo compound such as azodicarboxylic acid amide, a nitroso compound such as N, N′-dinitrosopentamethylenetetramine, a carbonic acid such as sodium bicarbonate, sodium bicarbonate, and ammonium bicarbonate. Examples thereof include salts, organic acids such as citric acid, sodium citrate and oxalic acid. Since these foaming agent components generate gas by thermal decomposition or vaporization, it is preferable to select an optimal one according to the molding temperature.

  Moreover, the foaming agent component which generates gas at the time of foam molding can be mix | blended when mix | blending the said (a)-(d) component in the said composition for foamed layers, and is mix | blended when foam-molding. You can also. When blending the components (a) to (d) in the foam layer composition, when blending the foaming agent component, it is necessary to adjust the blending temperature so that the foaming agent component does not decompose or vaporize during the blending. .

Moreover, the said composition for foam layers mix | blends other arbitrary compounding components according to the objective in the range which does not impair the effect of this invention other than said (a)-(d) component and a foaming agent. Can do.
Examples of optional ingredients include fillers, antioxidants, heat stabilizers, light stabilizers, UV absorbers, neutralizers, lubricants, antifogging agents, antiblocking agents, slip agents, dispersants, and coloring agents. Agents, flame retardants, antistatic agents, conductivity-imparting agents, metal deactivators, molecular weight modifiers, antibacterial agents, antifungal agents, fluorescent brighteners and other additives, (a) to (d) above There are thermoplastic resins, elastomers, fillers and the like other than the components, and any of these can be used alone or in combination.

  Examples of thermoplastic resins other than the components (a) to (d) include polyphenylene ether resins, polyamide resins such as nylon 6 and nylon 66, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, and polyoxymethylene. There are polyoxymethylene resins such as homopolymers and polyoxymethylene copolymers, and polymethyl methacrylate resins.

  Examples of elastomers other than the components (a) to (d) include olefin rubbers such as ethylene / propylene copolymer rubber, ethylene / propylene / nonconjugated diene copolymer rubber, styrene rubber, and polybutadiene. . Further, examples of the filler include glass fiber, hollow glass sphere, carbon fiber, talc, calcium carbonate, mica, potassium titanate fiber, silica, metal soap, titanium dioxide, and carbon black.

The composite molded body of the present invention is characterized in that, as the property of (a) above, the foam layer composition according to JIS-K6253 has a type A hardness of 80 or less and the surface hardness of the foam layer according to Asker C. Has a property of 75 or less.
When the type A hardness (hardness measured by a type A hardness meter) of the composition for the foam layer is 80 or less, the softness of the whole foam layer (soft feeling with low rebound resilience) can be exhibited and the surface of the foam layer When the hardness is 75 or less, a soft feeling when contacting the surface of the foamed layer can be exhibited.
The type A hardness of the foam layer composition was determined as the hardness of an unfoamed molded product obtained by injection molding of the foam layer composition.

  Moreover, when the type A hardness of the composition for a foam layer and the surface hardness of the foam layer are too small (soft), when the composite molded body is used, the polyolefin composite resin layer (base material) bottoms out. There is a risk that a sufficient elasticity will not be obtained. Therefore, the type A hardness of the foam layer composition is preferably 60 or more, and the surface hardness of the foam layer is preferably 50 or more.

The surface hardness of the foamed layer is determined by the foaming ratio and the type of the foamed layer composition. In addition, the surface hardness of the foamed layer is also affected by the generation state of bubbles (closed cells or open cells) and the thickness of the unfoamed surface layer.
When a high-hardness material is used for the foamed layer composition, the foamed surface layer tends to be thick, and the foam wall needs to have a high foaming ratio because of high rigidity of the cell walls. If the foaming layer composition is made of a low-hardness material and the foaming ratio is set low, a soft surface can be easily obtained.

The composite molded body of the present invention has a property that the foaming ratio of the foamed layer is 1.2 times or more, that is, the property of (b) above, that is, the foamed layer composition is foamed at a foaming ratio of 1.2 times or more It has the property to be formed.
When the expansion ratio is 1.2 times or more, the soft feeling of the foam layer can be appropriately maintained. On the other hand, if the foaming ratio is set too large, it is difficult to form foam cells having uniformity, and molding cracks may occur in the foam layer. Therefore, it is preferable to set the expansion ratio to 5 times or less.
In addition, the expansion ratio is determined by the amount of expansion of the inner volume of the mold when the foam volume composition is subjected to foam injection molding by expanding the inner volume of the mold described later. Strictly speaking, the expansion ratio can be calculated by density measurement.

The composite molded body of the present invention has a property that the melt ductility of the foamed layer composition as a molding material is 80 m / min or more at 170 to 190 ° C. as the property (c).
This melt spreadability is obtained when the molten resin is extruded from an extrusion port having a length of 8 mm and an inner diameter of 2.095 mm at an extrusion speed of 10 mm / min, and the resin is cut when the take-up speed of the extruded molten resin is increased. Indicates the value of the take-off speed. Moreover, the temperature at the time of extruding molten resin was 170-190 degreeC.

When the melt spreadability of the composition for a foam layer at 170 to 190 ° C. is less than 80 m / min, the foamability of the foam layer may be lowered.
In addition, the melt ductility value is preferably 500 m / min or less because if the ductility is more than necessary, the uniformity of the foamed cells may be affected.

  Further, in ordinary resins, the melt ductility increases as the temperature decreases, but in styrene-based elastomers, it tends to decrease as the temperature decreases. Therefore, in particular, when a styrene elastomer is used as the aromatic vinyl compound in the component (a) of the foam layer composition, the melt ductility at 170 to 190 ° C. is less than 80 m / min. There is a possibility that uniform foam cells (bubbles) may not be generated.

The composite molded body of the present invention has a property of the above (d), in the TMA measurement value of the foamed layer composition in accordance with JIS-K7196, the temperature at the time of deformation of 0.1 mm is 100 ° C. or more and is 0. It has the property that the temperature when deformed by 5 mm is 120 ° C. or higher.
Thereby, the said foaming layer can exhibit the outstanding heat resistance, although it is low hardness. When the temperature at the time of deformation of 0.1 mm is less than 100 ° C. or the temperature at the time of deformation of 0.5 mm is less than 120 ° C., the heat resistance of the foam layer may not be sufficiently exhibited.

In addition, the TMA measurement value is such that the temperature at the time of 0.1 mm deformation is 170 ° C. or less and the temperature at the time of 0.5 mm deformation is 160 ° C. or less, considering the composition of the foam layer composition. preferable.
Moreover, the said TMA measurement value is the value calculated | required based on JIS-K7196 (The softening temperature test method by the thermomechanical analysis of a thermoplastic film and a sheet | seat).

By the way, as a high-temperature body that is in direct contact with general use, there are few that have a boiling point of 100 ° C. or more, which is the boiling point of water, and the temperature rise when exposed to direct sunlight is also 100 ° C. or more from experience. There is hardly anything. In particular, when the temperature at the time of deformation of 0.1 mm is 100 ° C. or more, for example, in the instrument panel of an automobile, a phenomenon that a dent occurs when a hot body such as hot can juice is placed, or direct sunlight in summer It is possible to prevent a phenomenon in which deformation occurs when the temperature rises due to leaving it in a location where it hits.
Therefore, the heat resistance of the foamed layer can be kept high by setting the temperature at the time of 0.1 mm deformation to 100 ° C. or higher and the temperature at the time of 0.5 mm deformation to 120 ° C. or higher.
Moreover, by maintaining the heat resistance of the foam layer high, it is possible to prevent the appearance of the foam from being deformed at 100 ° C. even if it is a foam.

  As described above, according to the present invention, the foamed layer composition containing the components (a) to (d) is injection-molded to obtain a foamed layer having the properties (a) to (d) above. By molding, it is possible to provide a composite molded article having excellent foaming characteristics, soft feeling and heat resistance.

A preferred embodiment of the present invention described above will be described.
In the present invention, the composite molded body is used for members that require a wide range of cushioning properties such as automobile interior materials (instrument panels, door panels, seat back panels, steering wheels, etc.), home appliances, furniture (cushion portions, etc.). can do.

  As the blending method of the above components (a) to (d) in the foamed layer composition, there are generally used melting method, solution method, suspension dispersion method, etc., and practically a melt kneading method is adopted. It is preferable to do. As this melt-kneading method, the above components (a) to (d) are uniformly mixed using a Henschel mixer, ribbon blender, V-type blender, etc. The method of kneading using a normal kneader can be exemplified.

The temperature at which the components (a) to (d) are melted and kneaded exceeds the melting point of each component and is not less than the temperature at which the components are brought into a molten state.
In addition, when blending the above-mentioned components (a) to (d) with a foaming agent component that generates gas during foam molding, the temperature at which the melt-kneading is carried out is 180, although depending on the type of foaming agent component to be blended. It is preferable that it is below ℃.
Further, the order and method of kneading the components (a) to (d) are not particularly limited, and a method of kneading all the components at once or a part of the components after kneading, then additional components A method of kneading the remaining components including can be employed.

In addition, as the polyolefin-based composite resin layer as a base material in the composite molded body, various polyolefin-based composite resin materials satisfying the rigidity, heat resistance, durability, etc. required in applications using the composite molded body Can be molded from
Specifically, the polyolefin-based composite resin material can be a composite resin material in which reinforcing fillers such as talc, mica, calcium carbonate, and glass fiber are blended with a polyolefin resin such as polypropylene and polyethylene. The polyolefin resin constituting the polyolefin-based composite resin layer includes ethylene-propylene rubber, ethylene-propylene-diene rubber, styrene-butadiene-styrene block copolymer (and its hydrogenated product), styrene-isoprene-styrene block copolymer. Polymer (and its hydrogenated product).

  In addition to the above, polyolefin composite resin materials include polystyrene, high impact polystyrene (HIPS), polystyrene resins such as acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, polycarbonate, and polymethyl. Acrylic resins such as methacrylate, polyphenylene ether, polyester elastomers, polyamide elastomers, elastomers having polar groups such as polyurethane elastomers, polyesters such as polyethylene terephthalate and polybutylene terephthalate, nylon 6, nylon 11 and nylon 12 Polyamides and the like may be contained.

In the present invention, the foamed layer is formed by disposing the polyolefin composite resin layer in the mold or by injection molding, and then enlarging the internal volume of the mold or attaching another mold to the mold to form a void portion. Preferably, the foamed layer composition is foamed by injection molding the foam layer composition into the void portion, and further enlarging the void portion by enlarging the internal volume of the mold (claim 2).
In this case, the expansion ratio of the foam layer composition can be easily set, and the foam layer composition can be foamed in an optimal state.

  Further, the inner volume of the molding die can be increased by making the partition located on the side where the foam layer is formed in the molding die a movable die and moving the movable die. Further, the amount of expansion of the inner volume of the mold after injecting the foam layer composition is appropriately determined depending on the thickness of the foam layer and the design of the expansion ratio.

  In addition, the foamed layer has a polyolefin-based composite resin molded product as the polyolefin-based composite resin layer disposed in a mold (mold), and the foam layer composition is injection-molded in a void portion in the mold. It can also be formed. In this case, the polyolefin-based composite resin layer can be molded using, for example, injection molding, press molding, vacuum molding, or the like. Then, the polyolefin-based composite resin layer (molded product) is mounted in a mold for foaming and injection-molding the foam layer, and a void portion is formed on the side where the foam layer is formed in the mold, and the foam layer is formed in the void portion. Can be foam injection molded.

  When the foam layer is foamed and injection molded in the mold, the foaming agent and the like are introduced into the mold in addition to the components (a) to (d) in the foam layer composition. . And especially when using the foaming agent component which generate | occur | produces gas at the time of foam molding as a foaming agent, the temperature in the cylinder of an injection molding machine shall be more than the temperature which a foaming agent component can generate | occur | produce gas sufficiently.

Moreover, it is preferable to set the pressure inside the injection cylinder before starting the injection of the foamed layer composition into the mold in the range of 1 to 500 MPa. If the pressure inside the injection cylinder is lower than 1 MPa, the amount of foam gas dissolved in the foam layer composition is lowered, and the foam gas in the foam layer composition may escape to the outside.
Moreover, the injection pressure at the time of performing the foam injection molding of the composition for a foam layer can be set in the range of 10-1500 MPa.

  Moreover, when foaming is performed by enlarging the inner volume of the mold, it is preferable that the foam layer composition is sufficiently filled in the voids in the mold. When the filling amount of the composition for the foam layer is insufficient in the void portion, sufficient foaming magnification and foam cell uniformity cannot be obtained, the surface appearance of the foam layer is deteriorated, and the polyolefin composite resin layer There is a possibility that the integrated strength and the like of the material may be reduced.

  Further, when the foam layer composition is subjected to foam injection molding, it is preferable that the temperature of the foam layer composition is set to a predetermined temperature or higher to melt the surface of the polyolefin-based composite resin layer. When the foamed layer is integrally formed with the polyolefin-based composite resin layer, it is preferable to mold the composite molded body in a state where these are fused. When the molding temperature of foam injection molding is too low, or when the filling amount of the composition for the foam layer is insufficient and the pressure applied to the polyolefin composite resin layer is low, the surface of the polyolefin composite resin layer is sufficient. The foamed layer may not be melted and the foamed layer may be peeled off from the polyolefin-based composite resin layer.

  Moreover, the part for foaming layer composition which is cooled and solidified before foaming produces | generates in the part which contacts a shaping | molding die, or the part which contacts a polyolefin-type composite resin layer. This solidified portion remains on the surface of the foam layer without foaming. The thickness of the unfoamed solidified portion (skin layer) varies depending on various other conditions such as the molding temperature, the temperature of the mold, the time required for injection and filling of the foamed layer, the thickness of the void portion, and the like. The thinner the skin layer, the better the soft feeling, but the thickness can be arbitrarily determined depending on the required performance, foaming ratio, part design, and the like. Moreover, when the thickness of the skin layer is too thin, appearance defects such as perforations and dents on the surface may occur.

The temperature of the mold can be set to a general temperature for molding. If the mold temperature is low, the thickness of the unfoamed portion tends to be thick, and if the mold temperature is high, the injection cycle becomes long.
The time until completion of injection is preferably as short as possible. If the length is longer, foaming progresses until the completion of injection, and it is difficult to obtain a good foam. In addition, the thickness of the unfoamed portion on the surface increases and the soft feeling is lost.

  Moreover, when expanding the foam layer composition by expanding the internal volume of the mold, it is preferable to set the time from the completion of the injection of the foam layer composition to the expansion of the internal volume as short as possible. As a result, the thickness of the unfoamed solidified portion (skin layer) described above can be reduced, the foaming ratio can be easily increased, and the unevenness and cracking of the cell walls can be reduced.

  In the case where the foamed layer composition is injection-molded in the gap formed by expanding the inner volume of the mold, the speed of expanding the inner volume of the mold is determined by the expansion ratio, molding temperature, mold The temperature can be determined in consideration of the temperature. If this speed is too high, the bubble wall breaks and the like tend to be remarkable, and if it is too slow, the required expansion ratio tends to be not obtained. Further, when the expansion of the inner volume of the molding die is completed, the state is maintained for a certain time, the mold is opened, and the composite molded body is taken out. The appropriate time for cooling the composite molded body varies depending on various conditions, but generally about 30 seconds are required.

Hereinafter, examples of the composite molded body of the present invention will be described with reference to the drawings.
The composite molded body of this example is formed by integrally foaming a foamed layer by foaming and injection-molding a composition for a foamed layer on a polyolefin-based composite resin layer injection-molded in a mold. The foam layer is formed by injection-molding a polyolefin-based composite resin layer in a mold, then expanding the inner volume of the mold to form a void portion, and injection-molding the composition for the foam layer into the void portion. Further, foaming is performed by enlarging the inner space of the mold and enlarging the gap.

The foam layer has the following properties (a) to (d) by performing foam injection molding using the foam layer composition containing the following components (a) to (d). .
That is, the foam layer composition comprises (a) a hydrogenated block copolymer having a weight average molecular weight of 200,000 or less having an aromatic vinyl compound block and a conjugated diene compound block, and (b) a propylene-based polymer. , (C) a softening material for rubber, and (d) a propylene-based system comprising 30 to 70% by weight of a crystalline propylene polymer containing propylene, with the balance being propylene and ethylene. Each component with the polymer mixture is contained. Moreover, the composition for foamed layers contains the foaming agent component.

  The foam layer composition or foam layer has (a) a foam layer composition conforming to JIS-K6253 having a type A hardness of 80 or less and a foam layer conforming to Asker C having a surface hardness of 75 or less. (B) The foaming ratio of the foamed layer is 1.2 times or more, (c) the melt ductility of the composition for the foamed layer is 80 m / min or more at 170 to 190 ° C., and (d) JIS- In the TMA measured value of the composition for a foam layer in accordance with K7196, the temperature at the time of 0.1 mm deformation is 100 ° C. or higher and the temperature at the time of 0.5 mm deformation is 120 ° C. or higher.

Moreover, in this example, the composition for foamed layers containing said (a)-(d) and the foamed layer shape | molded using this are made into invention products 1-4, and the said (a)-for comparison. The composition for foaming layers which does not contain any of (d) (especially (d) component) and the foamed layer shape | molded using this were made into the comparative products 1-4.
The configurations of the inventive products 1 to 4 are shown in the upper part of Table 1, and the configurations of the comparative products 1 to 4 are shown in the upper part of Table 2.

  In Tables 1 and 2, the content of the components (a) to (e) is expressed as% by weight with respect to the entire foam layer composition, and the content of the foaming agent component is 100 parts by weight of the entire foam layer composition. As shown in parts by weight.

Below, (a)-(d) component in the composition for foamed layers used in invention products 1-4 and comparative products 1-4, (e) component in the composition for foamed layers used in comparative products 1-4 The foaming agent component will be described.
(A) Component a-1: Hydrogenated product of styrene-butadiene-styrene block copolymer (29% by weight of styrene, weight average molecular weight of block copolymer 70,000)
a-2: Hydrogenated product of styrene-butadiene-styrene block copolymer (styrene 30% by weight, weight average molecular weight of block copolymer 100,000)
a-3: Hydrogenated product of styrene-butadiene-styrene block copolymer (styrene 20% by weight, weight average molecular weight of block copolymer 140,000)
a-4: Hydrogenated product of styrene-butadiene-styrene block copolymer (33% by weight of styrene, weight average molecular weight of block copolymer 230,000)

(B) Component b-1: Block polypropylene (MFR 10 g / 10 min)
b-2; random polypropylene (MFR 30 g / 10 min)
b-3: Random-block polypropylene (MFR 30 g / 10 min)
b-4; random polypropylene (MFR 1.5 g / 10 min)

(C) Component c-1: Paraffin oil (impurity 0.2% by weight or less, weight average molecular weight 550)
(D) Component d-1: containing 50% by weight of polypropylene (homopolymer having an isotactic index of 90% or more) and 50% by weight of ethylene-propylene copolymer (weight average molecular weight 900,000), After polymerization, an elastomer composition obtained by polymerizing an ethylene-propylene copolymer (MFR 1 g / 10 min).

(E) Component e-1; low density polyethylene (MFR 5 g / 10 min)
e-2; ethylene-propylene rubber (MFR 0.5 g / 10 min)
Foaming agent component f-1; Fine blow S20N (blowing agent masterbatch containing inorganic salt and organic acid mixture)

In the above components (b), (d), and (e), the value of MFR (melt flow rate) is measured in accordance with JIS-K7210, and in the components (b) and (d), 230 ° C. The component (e) was measured under the conditions of 190 ° C. and a load of 21 N.
Moreover, the composition for the foamed layer in the said invention products 1-4 and the composition in the said comparative products 1-4 use the biaxial kneader (Ikegai Iron Works Co., Ltd. PCM45), temperature 200 degreeC, rotation speed 200rpm, discharge It knead | mixed on the conditions of the quantity of 40 kg / hr, and manufactured in the pellet state.
Moreover, the foamed layer in the said invention products 1-4 and the foamed layer in the said comparative products 1-4 were shape | molded using the injection molding machine (Mitsubishi Heavy Industries MS series) with a core back function.

That is, first, a polypropylene composite material having a thickness of 3 mm as the polyolefin composite resin layer is injection molded into a mold of an injection molding machine, and then the movable part of the mold is moved to form a polypropylene composite material. A 3 mm gap was formed adjacently. Subsequently, CO ₂ gas was injected into the injection cylinder at a pressure of 3 MPa, and the above-described void portion was filled with the foamed layer composition in Inventions 1 to 4 or the composition in Comparative Products 1 to 4.
Thereafter, the movable part of the mold is further moved to enlarge the internal volume of the void part, and the foam layer composition or composition is foamed to a predetermined foaming ratio (2 times or 1.7 times), The intended foamed layer was molded.

Next, the foamed layer and the foamed layer composition constituting the invention products 1 to 4 and comparative products 1 to 4 will be described with respect to methods for measuring the properties (a) to (d).
Moreover, in this example, it tested about the item of the following (1)-(7) which shows those properties about the foam layer and the composition for foam layers.
In the tests for each item, the tests for items (1) and (2) indicate the property (a), the item (3) indicates the property (b), and the test for the item (6) The property of (c) is shown, and the test of item (7) shows the property of (d).

(Measurement of each property)
(1) Type A hardness: The hardness of an unfoamed molded article obtained by injection molding of the foam layer composition was measured according to JIS-K6253 (JIS-A, durometer hardness test).
(2) Surface hardness: The surface hardness of the foam layer (foam) obtained by foam injection molding the foam layer composition was measured according to Asker C (Japan Rubber Association Standard).
(3) Foaming ratio: The thickness (mm) of the foam layer (foam) after foam molding was divided by the thickness (mm) of the gap when the foam layer composition was filled in the mold. Value.

(4) MFR: Measured according to JIS-K7210 (230 ° C., load 21 N).
(5) Melt viscosity (melt tension): When the molten resin is extruded from an extrusion port having a length of 8 mm and an inner diameter of 2.095 mm at an extrusion speed of 10 mm / min, and the extruded molten resin is taken up at a speed of 4 m / min. The tension value was measured as melt viscosity. The melt viscosity was measured by setting the temperature of the molten resin at two stages of 170 ° C. and 190 ° C. The melt viscosity was measured using a melt tension tester type II (manufactured by Toyo Seiki Seisakusho Co., Ltd.), and the outer diameter of the die forming the extrusion port was 9.5 mm.
(6) Melt spreadability: When the take-up speed was increased under the same measuring machine and the same conditions as in (5), the take-up speed when the resin was cut was measured.
Moreover, in the test of the item of said (4)-(6), what fuse | melted the pellet of the composition for foamed layers was used.

(7) TMA measurement: In accordance with JIS-K7196, the measurement atmosphere is air (flow rate 50 to 100 ml / min), the temperature rising speed is 5 ° C./min, the probe diameter is 1 mm, and the foamed layer composition is injected. The temperature when the unfoamed molded body obtained by molding was deformed by 0.1 mm and 0.5 mm was measured.
Moreover, in the test of the item of said (1) and (7), it does not mix | blend foaming agent component f-1, but uses an in-line screw type injection molding machine ("IS100" by Toshiba Machine Co., Ltd.), and composition for foaming layers An unfoamed sheet (120 mm wide, 120 mm long, 2 mm thick) obtained by injection molding the product under conditions of an injection pressure of 50 MPa, a cylinder temperature of 21 ° C., and a mold temperature of 40 ° C. was used.

  About the said invention products 1-4 and the comparative products 1-4, the result of having done the test of the item of said (1)-(7) is shown in the middle stage of Table 1, and the middle stage of Table 2. From this result, it can be seen that the inventive products 1 to 4 satisfy the above properties (a) to (d).

Moreover, in this example, about the foamed layer in the said invention products 1-4 and the comparative products 1-4, the evaluation of the characteristic of the following (8)-(10), the test of the characteristic of (11), (12), and Evaluation was performed.
(Evaluation of each characteristic)
(8) Foaming property (bubble generation state): A foamed layer (foam) obtained by injection molding the foam layer composition was cut out and the bubble (cell) generation state was confirmed with a stereomicroscope (magnification 10 times) did. In the evaluation of foaming property, the bubble is broken and a hollow layer is formed or a cell having a size of 2 mm or more can be confirmed x, the cell size is not uniform but many cells of less than 2 mm can be confirmed. The case was Δ, and the case where uniform bubbles were generated was ○.

(9) Appearance: In the foamed layer (foam) obtained by injection molding the composition for the foamed layer, dents such as avatars (bubble removal), weld lines (lines that can be fused to the resin), and the like, and It was confirmed whether or not there was transfer unevenness such as embossing or sink marks due to the mold. In the evaluation of the appearance of the foamed layer, “◯” indicates that there is no practical problem, and “x” indicates that the defect is conspicuous and causes a practical problem.

(10) Soft feeling (soft feeling with low impact resilience); The soft feeling when the surface of the foam layer (foam) obtained by injection molding the foam layer composition was pressed with a finger was confirmed. This feeling is evaluated by comparing the polyurethane foam with a vinyl chloride skin (which is often found in general instrument panels) with ○ having a soft feeling, △ with a slightly harder, and hard with an unacceptable level. X.

(Evaluation of each test and characteristics)
(11) Irradiation heat resistance test: The surface temperature of the foam layer with respect to a sample of a composite molded body in which the foam layer (foam) obtained by injection molding of the composition for the foam layer is integrally molded with a polyolefin-based composite resin layer. Was irradiated with infrared rays so that the temperature became 110 ° C. and left for 90 hours. Thereafter, the foamed layer in the above sample which was allowed to cool to room temperature was observed, and “O” indicates that there was no change in appearance, and “X” indicates that deformation was observed in whole or in part.

(12) Hot load resistance test; test piece in which a load of 360 g was put on a metal container having a diameter of 50 to 60 mm on the surface of a foam layer (foam) obtained by injection molding of the composition for a foam layer The foam and test piece in this state were placed in an oven at 110 ° C. and left for 3 hours. Moreover, the width | variety of the outer peripheral part in the test piece which contacts a foam was 2-3 mm. Then, the foam was allowed to cool to room temperature, and after removing the container from the foam, it was observed whether a dent or a mark was formed on the foam from the metal container.
In the evaluation of this hot load resistance test, the case where the dent is large is indicated by “X”, the case where the dent is not substantially concave but the trace remains clearly is indicated by “Δ”, and the case where the dent is substantially inconspicuous is indicated by “◯”.
In addition, about the comparative products 5 and 6, since the favorable foam was not obtained, evaluation of said (9)-(12) was not implemented.

The results of the above evaluations (8) to (12) for the inventive products 1 to 4 and the comparative products 1 to 4 are shown in the lower part of Table 1 and the lower part of Table 2. From these results, the inventive products 1 to 4 were evaluated in any of the characteristics evaluations of (8) foamability, (9) appearance, (10) soft feeling, (11) irradiation heat resistance test and (12) hot load resistance test. , ◯ or Δ was obtained, and it was found that all the characteristics were excellent.
On the other hand, the comparative products 1 to 4 were evaluated as x in any of the characteristics evaluations (8) to (12), and it was found that either of the characteristics was inferior to the invention product.

From the above, the inventive products 1 to 4, that is, the foamed layer in the composite molded body satisfies the above properties (a) to (d), that is, (1) type A hardness, (2) surface hardness, By satisfying the values of (3) foaming ratio, (6) melt spreadability and (7) TMA measurement value, the uniformity of the foam cell, the appearance of the foam layer surface, the soft feeling of the foam layer and the heat resistance It was found that both properties were excellent.
Moreover, it turned out that the foaming layer (invention products 1-4) in a composite molded object is excellent also in production efficiency by (6) large melt ductility.

Furthermore, the composite molded body having the foamed layer is excellent in heat resistance, so that, for example, in heat treatment in processing such as painting or in automobile interior materials, it is used under high temperatures (in summer, hot cans, etc.). It has been confirmed that it is possible to prevent the occurrence of problems such as deformation in the case of placing them.
In particular, it was confirmed that the use of automobile interior materials (instrument panels, door panels, seat back panels, steering wheels, etc.) and the like can be advantageously used in terms of productivity and performance.

Claims (2)

A composite molded body obtained by integrally forming a foam layer by foam injection molding the foam layer composition on a polyolefin-based composite resin layer placed or injection molded in a mold,
The foam layer composition is
(A) a hydrogenated block copolymer having a weight average molecular weight of 200,000 or less having an aromatic vinyl compound block and a conjugated diene compound block;
(B) a propylene-based polymer;
(C) a softening material for rubber;
(D) containing 30 to 70% by weight of a crystalline propylene polymer, with the remainder comprising each component of a propylene-based polymer mixture made of an amorphous copolymer containing propylene and ethylene,
The foam layer composition or the foam layer is
(I) The foam layer composition conforming to JIS-K6253 has a type A hardness of 80 or less, and the foam layer conforming to Asker C has a surface hardness of 75 or less.
(B) The foaming ratio of the foamed layer is 1.2 times or more,
(C) The melt ductility of the composition for a foam layer is 80 m / min or more at 170 to 190 ° C.,
(D) In the TMA measurement value of the foamed layer composition in accordance with JIS-K7196, each property has a temperature at the time of 0.1 mm deformation of 100 ° C. or higher and a temperature at the time of 0.5 mm deformation of 120 ° C. or higher. A composite molded body characterized by comprising:   2. The foamed layer according to claim 1, wherein the foamed layer is formed by disposing the polyolefin-based composite resin layer in the mold or by injection molding, and then enlarging the inner volume of the mold or attaching another mold to the mold. And forming the foam layer composition by injection molding into the void portion, and further expanding the void volume by expanding the inner volume of the mold. .