JP2013129757A - Foamable polypropylene-based resin composition, foamed molding, and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a foamable polypropylene-based resin composition which exhibits excellent surface appearance, scratch resistance and is free from sticky feeling even in a wide range of injection rates (molding shear rates), and which is high in foaming magnification, imparted with a good steady (rigid) feeling, allows considerable reduction in weight, and is excellent in recyclability, and to provide a foamed molding and a method for producing the same.SOLUTION: The foamable polypropylene-based resin composition includes a propylene-ethylene block copolymer having specific properties (i) to (iv), a specific ethylene polymer, a filler and a foaming agent. There are also provided the foamed molding and the method for producing the same.

Description

  The present invention relates to a foamable polypropylene resin composition, a foamed molded product, and a method for producing the same, and more specifically, even under a wide range of injection rate (molding shear rate), a turbulent flow is generated in the melt front (resin flow front end). It is difficult to envelop and foam, has excellent surface appearance and scratch resistance, has no sticky feel, has a high expansion ratio, has a firm feeling (rigidity), can be significantly reduced in weight, and is excellent in recyclability In addition, the present invention relates to a foamable polypropylene resin composition, a foamed molded product, and a method for producing the same.

Conventionally, polypropylene-based resins have good physical properties and moldability, and their use range is rapidly expanding as environmentally friendly materials. In particular, for automobile parts and the like, lightweight polypropylene-based resin products having excellent rigidity are provided, and one of such products is a polypropylene resin foam molded product.
For example, in the injection molding of polypropylene resin, so-called injection foam molding for foaming has been conventionally performed for the purpose of weight reduction, cost reduction, and prevention of warping and sink marks of the molded body.
In recent years, for example, in the automobile field, further weight reduction has been achieved in order to improve fuel consumption (reducing CO ₂ emissions), and it has been necessary to significantly reduce the thickness, for example, to form a product having a thin portion of about 1 to 2 mm. is there.
However, the polypropylene resin has a low melt tension (melting tension), and bubbles are easily broken. As a result, voids were easily generated inside, and it was difficult to increase the expansion ratio. Moreover, since the bubbles were non-uniform and large, the resulting molded article was not sufficiently rigid.
In addition, the void said here means the bubble which is a coarse bubble produced, for example, when internal bubbles communicate with each other and substantially has a diameter exceeding 1.0 mm.

  As a method for improving the foamability of polypropylene, for example, a method is proposed in which a foam is produced by adding a foaming agent and a crosslinking aid to polypropylene and crosslinking the molecules (see, for example, Patent Document 1). .) However, in this method, the melt tension of polypropylene is not sufficiently improved, and in such a polypropylene, a crosslinking aid that does not crosslink remains, so that odor becomes a problem.

By introducing long-chain branching by radiation irradiation, the melt tension is higher than that of a normal linear polypropylene resin, and the viscosity increases as the stretch distortion of the melt increases. The resin is commercially available from Sun Allomer as HMS-PP (High Melt Strength Polypropylene) (see Patent Document 2).
It is also known that a foamed molded article can be obtained by using such HMS-PP as a base resin for injection foam molding (see Patent Document 3).
Usually, in order to achieve significant weight reduction while maintaining rigidity, the mold cavity clearance thickness (thickness before foaming) at the time of injection filling is significantly thinner than the non-foamed injection molded body before weight reduction. And can be highly foamed. However, the HMS-PP used here has a melt flow rate of only about 4 g / 10 min and low fluidity at the time of melting, so it has a significant thickness reduction, for example, a thickness of about 1 to 2 mm. In molding, there is a problem that a short shot tends to occur. In addition, the thermoplastic resin having a crosslinked structure tends to be difficult to be melt-processed again, which increases the cost of the foamed molded product, and has a problem from the viewpoint of the amount of waste and the recycling of resources.

  Further, by using a thermoplastic resin that does not have a cross-linked structure that defines the melt index (MI) and the capillary swell ratio, good foam cell control and a foamed article with high appearance have been achieved (for example, Patent Document 4). However, as the molded body becomes larger, more complicated, and thinner, it is possible to obtain a foam molded body that maintains a good cell shape when foamed with a high magnification and reduced thickness before foaming. It was difficult.

  Also, by using a propylene-based multistage polymer or a propylene-based resin composition that defines the intrinsic viscosity of a propylene homopolymer component or copolymer component, and also a melt flow rate (MFR), it is excellent in foam moldability and appearance. Although an injection foamed molded product is obtained (see Patent Document 6), as the molded product becomes larger, complicated, and thinner, it tends to become a short shot and the appearance is often insufficient. .

  A resin composition comprising a crystalline propylene / ethylene block copolymer (A) and an ethylene / α-olefin copolymer (B), the melt of the n-decane insoluble part (a) of (A) A polypropylene resin composition suitable for producing a foamed molded article having high rigidity and penetrating impact strength with prescribed flow rate and Mz / Mw values, and a foamed molded article thereof have been proposed (see Patent Document 7). .) However, the foamed molded article using the resin composition has a relatively low foaming ratio and may be subject to restrictions on use, and there is a description of the level of scratch resistance and the presence or absence of sticky feel described later. No.

  A polypropylene resin composition comprising a propylene homopolymer component (A) and at least one ethylene-α-olefin copolymer component (B1) and having a melt index defined, wherein (A) A polypropylene resin composition excellent in moldability and appearance, in which the ratio between the intrinsic viscosity of (A) and the intrinsic viscosity of (B1) to the intrinsic viscosity of (A) has been proposed, and an injection-foamed molded article thereof (See Patent Document 8). However, the injection-foamed molded article using the polypropylene-based resin composition has a relatively low expansion ratio and is likely to be restricted in use. In addition to the above, there is a problem that it may be present on the entire surface, and there is no description about the level of scratch resistance and the presence or absence of sticky feel described later.

  Also, there is provided a polypropylene resin injection-foamed molded article having a skin layer and a foamed core layer, having a standard deviation of lightness on the surface of the molded article and an average value of gloss and having no appearance of silver streaks (white streaks). It has been proposed (see Patent Document 9). However, the injection-foamed molded article has a relatively low expansion ratio and may have a restriction on the injection capacity (absolute amount) per unit time, and there is a possibility that the application is likely to be limited particularly in the large-sized molded article field. is there. Moreover, there is no description about the level of scratch resistance and the presence or absence of sticky tactile sensation described later.

Further, the present applicant is composed of a linear propylene / ethylene block copolymer comprising a linear propylene polymer portion and a linear ethylene / propylene random copolymer portion, and other propylene-based polymers. A linear polypropylene resin composition comprising a polypropylene-based resin and a linear propylene / ethylene block copolymer containing a foaming agent and having a specific range of the melt flow rate of the linear propylene polymer portion, etc. The thing was proposed (refer patent document 10). When this linear polypropylene resin composition is used in an injection foam molded article, the surface appearance is excellent, the injection foam moldability is good, the foaming ratio is high, the weight can be significantly reduced, and the recyclability And improved physical properties such as rigidity.
However, as the changes in the actual product design, which are becoming larger, more complicated, and thinner, are accelerating, the resin composition (injection foamed molded product) includes, for example, prevention of molding burrs and gold accompanying resin filling When the injection rate (shear rate) during molding is set to a considerably low region in order to prevent the occurrence of so-called resin burn (black spots) caused by insufficient discharge of air in the mold, etc. It is desired to further improve the surface appearance, scratch resistance and foaming ratio described later.

On the other hand, as a manufacturing method for obtaining a foamed molded article having a good surface appearance, various methods have been conventionally proposed. For example, after forming a skin layer by injecting and filling a polypropylene resin into a narrow mold cavity while reversing the movable mold at a pressure equal to or higher than the foaming pressure, the movable mold is further retracted after the filling is completed. There is a manufacturing method for foaming, and according to this, a foamed molded article having a good surface appearance can be obtained without any special device (see, for example, Patent Document 11).
However, all of the foam-molded articles obtained by these methods have a low foaming ratio, and a foam-molded article having good scratch resistance and good surface appearance, which will be described later, has not been obtained.

  In addition, using a material composed of a linear polypropylene resin, a radical polymerization initiator and a modified polypropylene resin exhibiting strain hardening obtained by melt-kneading a conjugated diene compound, and a foaming agent, the mold is a fixed mold. And a step of injecting and filling the molten mixture into a cavity having a clearance (t0) smaller than the thickness (t1) of the molded body before foaming, which is composed of a movable mold capable of moving forward and backward, and then retracting the movable mold. A method for producing an injection foam molded body comprising a step of completing injection filling up to a clearance corresponding to the thickness (t1) of the molded body before foaming, and a step of foaming the polypropylene resin by retracting the movable mold has been proposed. (Refer to Patent Document 12), injection foam moldability and surface appearance are good, and an injection foam molded article having a high expansion ratio is obtained. However, as the molded body becomes larger, more complicated, and thinner, it tends to become a short shot, and the appearance, scratch resistance, a firm feeling (rigidity), expansion ratio, and recyclability described below are insufficient. There are many cases.

  A foamable polypropylene resin composition comprising a propylene / ethylene block copolymer (A), an ethylene / 1-butene copolymer rubber (B), an inorganic filler (C), and a foaming agent (D), In an injection molding machine equipped with a fixed mold and a movable mold, the initial position of the movable mold and the specific position and final position of the movable mold are defined. First, the injection is started from the initial position of the movable mold, and the movable mold is identified. A manufacturing method in which an outer skin layer and a highly foamed core material are molded from the same resin, comprising an injection filling process for terminating injection at a position, and a foaming process in which the movable mold is further retracted and foamed to the final position. Has been proposed (see Patent Document 13), and a foamed molded article having a good appearance, light weight, high rigidity and impact resistance is obtained. However, the obtained foamed molded article has a relatively low foaming ratio, and the level of the surface appearance (presence or absence of silver streak) of the injection foamed molded article when the injection rate at the time of injection molding is low and scratch resistance described later. The level of gender is unknown.

Moreover, 70-93 weight% of propylene-type polymers whose MFR (230 degreeC, 2.16 kg) is 5-150 (g / 10min), a density is 0.91-0.945 (g / cm < ³ >), MFR. (190 ° C., 2.16 kg) with respect to 100 parts by weight of a resin composition consisting of 7 to 30% by weight of linear low density polyethylene having 1 to 50 (g / 10 min), an inorganic chemical foaming agent 0.1 Polypropylene resin foam molding in which foamed resin composition is prepared by blending ~ 0.5 part by weight, and foam molding is performed using an injection mold having an average cavity clearance (t) of 1.0 mmt to 5.0 mmt. A method for manufacturing a body has been proposed (see Patent Document 14), and a polypropylene resin foamed molded body that can suppress the occurrence of silver streaks with little reduction in productivity has been obtained. However, the obtained resin foam molded article has a relatively low expansion ratio, and there is no description of their level and firm feeling (rigidity) regarding sticky touch feeling and scratch resistance described later.

On the other hand, in the foamable propylene-based resin composition and its (injection) foamed molded article, it is important to enhance the scratch resistance in terms of further expanding the application field and improving the texture.
For example, a syndiotactic α-olefin copolymer and another thermoplastic resin, and if necessary, an olefinic thermoplastic elastomer composition composed of an ethylene copolymer rubber, and a foaming agent, Foaming olefin-based thermoplastics that have a soft feel and no rough surface due to defoaming even when the density ρ is 700 kg / m ³ or less, and have excellent scratch resistance and abrasion resistance compared to conventional olefin-based thermoplastic elastomers. An elastomer composition and a foam obtained therefrom have been proposed (see Patent Document 15). However, the composition and the foam relate to their sticky feel, physical properties (impact strength, etc.), quality of the foam by the injection molding method (injection compression molding method), and a firm feeling (rigidity). There is no description, and their level is not clear.
In addition, the present applicant contains 20 to 90% by weight of a propylene-ethylene block copolymer satisfying the above four specific requirements and 10 to 80% by weight of a thermoplastic elastomer selected from an olefin elastomer or a styrene elastomer. A foamable resin composition in which 0.05 to 10 parts by weight of a foaming agent is added to 100 parts by weight of the propylene-ethylene block copolymer composition to be thermoformed and has two specific characteristics Proposed automotive interior parts with excellent flexibility and scratch resistance due to its softness, non-stickiness, and good mold texture transfer characteristics (Patent Literature) 16). However, as the changes in the actual product design, which are becoming larger, more complicated, and thinner, are accelerating, the foamable resin composition and automobile interior parts tend to have relatively low rigidity because they have flexibility. The foaming propylene-based resin composition and the injection-foamed molded product thereof have a firm feeling (relatively high rigidity (specifically, a flexural modulus of about 700 MPa or more)) Is desired for.

  Under such circumstances, the foamed molded body, which has solved the problems of the conventional foamable polypropylene resin composition, is large, has a more complicated design, and is thinner, especially the injection foamed molded body for automobile parts, especially trims. Even in a wide range of injection rate (molding shear rate), which is a necessary performance for obtaining injection foam moldings for automobile interior parts such as ceiling materials and trunks, the melt front (resin flow front end) is disturbed. Flow and foam are less likely to occur, silver streaks (white streaks) are less likely to occur, the surface appearance and scratch resistance of the foamed molded product are excellent, there is no sticky feel, the foaming ratio is high, and a solid feeling (rigidity) There is a need for a foamable polypropylene resin composition, a foamed molded article, and a method for producing the same, which can be significantly reduced in weight and excellent in recyclability.

Japanese Examined Patent Publication No. 45-40420 Japanese Patent Laid-Open No. 62-121704 JP 2001-26032 A JP-A-8-231816 JP 2004-307665 A International Publication WO2005 / 097842 Pamphlet JP 2003-253084 A JP 2006-152271 A JP 2006-150950 A JP 2010-150509 A JP 2003-11190 A JP 2005-224963 A JP 2002-283382 A JP 2004-300260 A JP 2007-269829 A JP 2011-79924 A

  In view of the above-mentioned problems of the prior art, the object of the present invention is that silver streak hardly causes turbulent flow and foam entrainment in the melt front (resin flow tip) even under a wide range of injection rate (molding shear rate). The surface appearance and scratch resistance of the foamed molded product is excellent, there is no sticky touch, the foaming ratio is high, there is a firm feeling (rigidity), and the weight can be significantly reduced, making it easy to recycle. Another object of the present invention is to provide a foamable polypropylene resin composition, a foamed molded article, and a method for producing the same.

  As a result of intensive studies to solve the above problems, the present inventors have found that the melt flow rate and molecular weight distribution value (Mw / Mn) of the propylene polymer component (A-1), propylene / ethylene random copolymer The die swell calculated from the diameter (D1) and the orifice diameter (D0) of the extruded melt when the melt flow rate and ethylene content of the component (A-2) are in a specific range and extruded at a specific shear rate. The ratio (D1 / D0) shows linearity when the common logarithm of the shear rate is taken as the horizontal axis (having no inflection point), propylene / ethylene block copolymer (A), filler (B), specific A foamable polypropylene resin composition containing an ethylene polymer (C) and a foaming agent (D) having a melt flow rate value of In addition, even under a wide range of injection rates (molding shear rate), turbulence, foam entrapment, and silver streaks (white streaks) are less likely to occur in the melt front (resin flow front end), resulting in improved surface appearance and scratch resistance. It has been found that a foamed molded article with a high expansion ratio that is excellent and has no sticky feel can be obtained, has a firm feeling (rigidity), can be significantly reduced in weight, and is excellent in recyclability. Based on the findings, the present invention has been completed.

That is, according to 1st invention of this invention, the foamable polypropylene resin composition characterized by containing the following (A)-(D) is provided.
(A): Propylene polymer component (A-1) 40 to 97% by weight and propylene / ethylene random copolymer component (A-2) 3 to 60% by weight (provided that component (A-1) and component (A) -2) and a propylene / ethylene block copolymer having the following characteristics (i) to (iv); 100 parts by weight (B): filler; 1 -10 parts by weight (C): ethylene polymer having the following characteristics (v); 1-15 parts by weight (D): foaming agent Characteristics (i): Melt flow of the entire propylene / ethylene block copolymer (A) The rate (230 ° C., 2.16 kg load) is 50 to 300 g / 10 min.
Characteristic (ii): The propylene polymer component (A-1) has a melt flow rate (230 ° C., 2.16 kg load) of 100 to 1500 g / 10 min and a molecular weight distribution value (Mw / Mn) of 3. 5 or less.
Characteristic (iii): Propylene / ethylene random copolymer component (A-2) has a melt flow rate (230 ° C., 2.16 kg load) of 0.8 to 55 g / 10 min, and propylene / ethylene random copolymer The ethylene content with respect to the total amount of the polymer component (A-2) is 35 to 60% by weight.
Characteristic (iv): When the propylene / ethylene block copolymer (A) was extruded at a shear rate of 400 to 10,000 / s in a 180 ° C. capillary rheometer, the measured value (D1) of the diameter of the extruded melt and the orifice diameter ( The die swell ratio (D1 / D0) calculated from D0) shows linearity with respect to the common logarithm of the shear rate (having no inflection point).
Characteristic (v): Melt flow rate (190 ° C., 2.16 kg load) is 5 to 60 g / 10 min.

According to the second invention of the present invention, there is provided a foamable polypropylene resin composition characterized in that, in the first invention, the filler (B) is talc.
According to the third invention of the present invention, in the first or second invention, the ethylene polymer (C) is a high density polyethylene (HDPE) and / or a linear low density polyethylene (LLDPE). An expandable polypropylene resin composition is provided.
According to a fourth aspect of the present invention, there is provided a foamable polypropylene resin composition characterized in that, in any one of the first to third aspects, the foaming agent (D) is a chemical foaming agent. Is done.

According to a fifth aspect of the present invention, in any one of the first to third aspects, the foaming agent (D) is supercritical carbon dioxide and / or supercritical nitrogen. A foamable polypropylene resin composition is provided.
According to a sixth aspect of the present invention, there is provided a foamable polypropylene resin composition characterized by further comprising the following (E) in any one of the first to fifth aspects: .
(E): Elastomer: 1 to 50 parts by weight According to the seventh invention of the present invention, in the sixth invention, the elastomer (E) is an ethylene / octene copolymer elastomer and / or an ethylene / butene copolymer. A foamable polypropylene resin composition which is a polymer elastomer and has a melt flow rate (230 ° C., 2.16 kg load) of the entire foamable polypropylene resin composition of 40 to 300 g / 10 min. Is provided.

In addition, according to the eighth invention of the present invention, there is provided a foamable polypropylene resin composition characterized by further containing an organic peroxide in any one of the first to seventh inventions.
According to a ninth aspect of the present invention, there is provided a foamed molded article comprising the expandable polypropylene resin composition according to any one of the first to eighth aspects. Is provided.
According to a tenth aspect of the present invention, in the ninth aspect, the foamed molded article has a skin layer on at least a part of the surface and has a foaming ratio of 2 to 10 times. Is provided.

Further, according to the eleventh invention of the present invention, in the ninth or tenth invention, it is obtained by injection foam molding under the condition of an injection rate of 50% / second with respect to 100% of the black colored and pre-foamed molded body filling volume. In the image analysis using the hue histogram by the scanner on the surface, the ratio of the number of pixels in the range of lightness of 100 to 255 among the lightness of 256 gradations (0 to 255 gradations) is 0 of the total number of pixels. There is provided a foamed molded product characterized by being ˜15%.
According to a twelfth aspect of the present invention, there is provided a foamed molded product according to any one of the ninth to eleventh aspects, which is used for automobile parts.
According to a thirteenth aspect of the present invention, there is provided a method for manufacturing a foamed molded article according to any of the ninth to eleventh aspects, wherein the mold is composed of a fixed mold and a movable mold capable of moving forward and backward. Is melted into a mold cavity having a mold cavity clearance (T0) smaller than the mold cavity clearance (T1) corresponding to the shape position of the foamed molded body. An injection step of injecting and filling the expandable polypropylene-based resin composition in a state or a semi-molten state under a condition of an injection rate of 10 to 450% / second with respect to a filling volume of 100% of the pre-foamed molded body, and the mold cavity clearance The movable mold is retracted to (T1), and is manufactured by a mold opening injection molding method including a foaming process in which the cavity of the mold cavity is filled with an expansion pressure by a foaming agent. Method for producing a foamed molded body wherein is provided.

As described above, the present invention relates to a foamable polypropylene resin composition and the like, and preferred embodiments include the following.
(1) In the first invention, the ethylene polymer (C) is a group consisting of high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), and linear low density polyethylene (LLDPE). A foamable polypropylene resin composition, wherein the foamable polypropylene resin composition is at least one polymer selected from the above.
(2) In the first invention, the foaming agent (D) comprises (i) sodium bicarbonate, sodium carbonate, ammonium bicarbonate, ammonium carbonate, ammonium nitrite, azodicarbonamide (ADCA), N, N′-dinitroso At least one chemical blowing agent selected from the group consisting of pentamethylenetetramine, benzenesulfonyl hydrazide and 4,4′-diphenyldisulfonyl azide, (ii) at least selected from the group consisting of carbon dioxide, nitrogen, argon and helium A foamable polypropylene resin composition, which is a microcapsule containing one or more physical foaming agents or (iii) a foaming agent (swelling agent).
(3) In the aspect of (2), the blending amount of the foaming agent (D) is 0.001 to 10 parts by weight with respect to (A) 100 parts by weight when (D) is a chemical foaming agent. When (D) is a physical foaming agent, it is the quantity which exhibits a supercritical state, The foamable polypropylene resin composition characterized by the above-mentioned.

The foamable polypropylene-based resin composition and foamed molded product of the present invention have a melt front (resin flow front end portion) even under a wide range of injection rates (molding shear rate), despite not performing cross-linking modification, etc. Due to turbulent flow and bubble encroachment and silver streak less likely to occur, the surface appearance and scratch resistance of the foamed molded product are excellent, there is no sticky feel, the foaming ratio is high, and there is a solid feeling (rigidity) It is possible to significantly reduce the weight and to exhibit a remarkable effect of being excellent in recyclability.
In particular, molding is possible in the region where the absolute molding wall thickness before foaming is less than 2 mm, especially 1.5 mm or less, which has been difficult in the past, and it is possible to significantly reduce the weight by expressing a uniform high foaming ratio. Become. In addition, since cross-linking modification is not performed, recyclability is excellent and environmental adaptability is also good. Therefore, it is suitable for molded parts applications such as automotive interior parts such as door trims, trims, ceiling materials, trunks, instrument panels, armrests, glove boxes, switch panels, pillars, consoles, and various decorative parts. Can be used.
Moreover, according to the manufacturing method of this invention, there exists an effect that the said expandable polypropylene resin composition and a foaming molding can be manufactured easily.

Shear rate dependence (inflection) of die swell ratio (D1 / D0) calculated from diameter (D1) and orifice diameter (D0) of extruded melt by capillary rheometer using two types of propylene / ethylene block copolymers It is a graph which shows the result of having investigated the presence or absence of a point. Here, the upper line is (component Ag) (used in Comparative Example 9), and the lower line is (component A-c) (used in Example 3). It is explanatory drawing which shows an example of the superposition | polymerization apparatus which manufactures the propylene ethylene block copolymer used in the Example.

The present invention includes a propylene polymer component (A-1, hereinafter simply referred to as component (A-1)) of 40 to 97% by weight and a propylene / ethylene random copolymer component (A-2, hereinafter simply component). (Also referred to as (A-2)) 3-60 wt% (provided that the total amount of component (A-1) and component (A-2) is 100 wt%) Polymer (A) (hereinafter also simply referred to as (A)), filler (B) (hereinafter also simply referred to as (B)), ethylene polymer (C) (hereinafter also simply referred to as (C)). And a foaming agent (D) (hereinafter also simply referred to as (D)), and optionally an elastomer (E) (hereinafter also simply referred to as (E)). It is a composition, a foaming molding, and its manufacturing method.
Hereinafter, each component of the expandable polypropylene resin composition, the method for manufacturing the expandable polypropylene resin composition, the method for manufacturing the foam molded article, and the like will be described in detail.

[I] Constituent Components of Expandable Polypropylene Resin Composition Propylene / ethylene block copolymer (A)
The propylene / ethylene block copolymer (A) used in the foamable polypropylene resin composition of the present invention is 40 to 97% by weight, preferably 50 to 96% by weight, of the propylene polymer component (A-1) described below. %, More preferably 60 to 95% by weight, propylene / ethylene random copolymer component (A-2) 3 to 60% by weight, preferably 4 to 50% by weight, more preferably 5 to 40% by weight (provided that It consists of component (A-1) and (the total amount of component (A-2) is 100% by weight) and has the following characteristics (i) to (iv).
Characteristic (i): (A) The overall melt flow rate (hereinafter also referred to as MFR) (230 ° C., 2.16 kg load) is 50 to 300 g / 10 min.
Property (ii): MFR (230 degreeC, 2.16kg load) of a component (A-1) is 100-1500 g / 10min, and molecular weight distribution value (Mw / Mn) is 3.5 or less.
Characteristic (iii): MFR (230 ° C., 2.16 kg load) of component (A-2) is 0.8 to 55 g / 10 min, and ethylene content relative to the total amount of component (A-2) is 35 to 60 % By weight.
Characteristic (iv): Die calculated from the measured value (D1) of the diameter of the extruded melt and the orifice diameter (D0) when (A) is extruded at a shear rate of 400 to 10,000 / s in a 180 ° C. capillary rheometer The well ratio (D1 / D0) exhibits linearity with respect to the common logarithm of the shear rate (having no inflection point).
In the foamable polypropylene resin composition of the present invention, the propylene / ethylene block copolymer (A) has a turbulent flow on the melt front (resin flow front end) even under a wide range of injection rate (molding shear rate). It has features such as preventing foam entrainment and making silver streak less likely to express a good surface appearance of foamed molded products, suppress stickiness, increase foaming magnification, and enhance the feeling firmly .
Here, when the component (A-1) is less than 40% by weight (that is, the component (A-2) exceeds 60% by weight), the foamable polypropylene resin composition of the present invention and the surface of the foamed molded product thereof Appearance, scratch resistance, expansion ratio and firmness may be reduced. Moreover, when a component (A-1) exceeds 97 weight% (namely, a component (A-2) is less than 3 weight%), there exists a possibility that impact strength may fall.

(1) Characteristic characteristics (i):
The MFR (230 ° C., 2.16 kg load) of the entire propylene / ethylene block copolymer (A) used in the present invention is 50 to 300 g / 10 min, preferably 60 to 250 g / 10 min, more preferably 65 to 300 g / 10 min. 200 g / 10 min. When the MFR is less than 50 g / 10 minutes, there is a possibility that a short shot may occur during molding of the expandable polypropylene resin composition into a foamed molded product or a large foamed molded product cannot be obtained. Furthermore, foamability is also inhibited, and there is a possibility that the expansion ratio is lowered. On the other hand, if it exceeds 300 g / 10 min, the surface appearance is deteriorated (decreased) such as the occurrence of silver streaks due to the turbulent flow and bubble entrainment easily occurring on the melt front, as well as filler (B) and ethylene weight described later. There is a possibility that the scratch resistance may be lowered or the impact strength may be lowered in view of poor dispersion of the coalesced (C). Further, molding burrs due to overfilling easily occur. In addition, the MFR (230 degreeC, 2.16kg load) value of (A) and a component (A-1) is a value measured based on JISK7210.

Characteristic (ii):
The MFR (230 ° C., 2.16 kg load) of the propylene polymer component (A-1) in the propylene / ethylene block copolymer (A) used in the present invention is 100 to 1500 g / 10 minutes, preferably 150 to 1200 g / 10 min, more preferably 200-600 g / 10 min, and the molecular weight distribution value (Mw / Mn) is 3.5 or less, preferably 0.5-3.5, more preferably 1-3. More preferably, it is 2-3. If the MFR is less than 100 g / 10 minutes, there is a possibility that short shots may occur during molding of the expandable polypropylene resin composition into a foamed molded product or a large foamed molded product cannot be obtained. Furthermore, foamability is also inhibited, and there is a possibility that the expansion ratio is lowered. On the other hand, if it exceeds 1500 g / 10 minutes, the surface appearance deteriorates due to the occurrence of silver streaks due to the turbulent flow and bubble entrainment that easily occur on the melt front, and the filler (B) and ethylene polymer (C ) May be poorly dispersed or the impact strength may be reduced. Further, molding burrs due to overfilling easily occur. Further, when the molecular weight distribution value (Mw / Mn) exceeds 3.5, the surface appearance is deteriorated due to the occurrence of silver streaks due to the turbulent flow and bubble entrainment at the melt front, and the sticky tactile sensation. It tends to occur. The specific measurement conditions for the molecular weight distribution value (Mw / Mn) will be described later in the examples.

Characteristic (iii):
The MFR (230 ° C., 2.16 kg load) of the propylene / ethylene random copolymer component (A-2) in the propylene / ethylene block copolymer (A) used in the present invention is 0.8 to 55 g / 10. Minute, preferably 1 to 40 g / 10 minutes, more preferably 1.5 to 20 g / 10 minutes, and the ethylene content relative to the total amount of component (A-2) is 35 to 60% by weight, preferably 39 to 55% % By weight, more preferably 40-50% by weight.
If the MFR is less than 0.8 g / 10 min, the surface appearance may be deteriorated due to the turbulent flow and foam entrainment that tend to occur when the foamable polypropylene resin composition is molded into a foamed molded product. The scratch resistance may be lowered from the viewpoint of poor dispersion of the filler (B) and the ethylene polymer (C) described later. On the other hand, if it exceeds 55 g / 10 minutes, sticky tactile sensation may occur or impact strength may be reduced.
In addition, since the MFR value of this component (A-2) cannot be directly measured, the MFR of the component (A-1) and the MFR of the whole (A) are measured and calculated by the following formula.
log (MFR of the whole (A)) = (100−Wc) / 100 × log (MFR of component (A-1)) + Wc / 100 × log (MFR of component (A-2))
Here, Wc is the ratio of the component (A-2) in (A), and is determined by the method of Examples described later.
Further, when the ethylene content relative to the total amount of the component (A-2) is less than 35% by weight, the component (A-2) and the component (A-1) are formed at the time of molding the expandable polypropylene resin composition into a foamed molded product. The dispersion form of the component (A-2) is changed from a so-called ball shape to a flat shape due to the compatibility change of the liquid, or the viscosity behavior is changed. The surface appearance deteriorates due to the occurrence of silver streaks, etc., and the scratch resistance is reduced from the viewpoint of poor dispersion of the filler (B) and ethylene polymer (C) described later, and in addition, the impact strength is reduced. May decrease. On the other hand, if it exceeds 60% by weight, the surface appearance and scratch resistance may be lowered due to the above-mentioned reasons.

Characteristic (iv):
The propylene / ethylene block copolymer (A) used in the present invention is a die swell calculated from an extrusion melt diameter D1 and an orifice diameter D0 when extruded at a shear rate of 400 to 10,000 / s in a 180 ° C. capillary rheometer. The ratio, D1 / D0, needs to exhibit linearity (no inflection point) as shown by the lower line segment in FIG. 1 when the horizontal axis is the common logarithm of the shear rate.
Here, as shown in the upper line of FIG. 1, when the linearity of the common logarithm of the shear rate is not shown (having an inflection point), the expandable polypropylene resin composition and its In the foamed molded article, silver streaks are generated due to the turbulent flow and bubble entrainment at the melt front because the dispersion state of component (A-2) becomes excessive or tends to be ball-shaped. The surface appearance may be deteriorated, and scratch resistance and impact strength may be reduced from the viewpoint of poor dispersion of the filler (B) and the ethylene polymer (C) described later. Absent.
Here, as to the method for evaluating whether or not it exhibits linearity (whether or not it has an inflection point), the propylene / ethylene block copolymer (A) at 180 ° C. is used using the capillary rheometer as described above. ) Is measured for the shear rate dependence of the D1 / D0 (die swell ratio). Specific measurement conditions will be described later in Examples.

Further, it is preferable that the propylene / ethylene block copolymer (A) does not cause a melt fracture (ripple phenomenon) when extruded at a shear rate of 400 to 10,000 / s in a 180 ° C. capillary rheometer.
When a melt fracture occurs, the foamed polypropylene resin composition and the foamed molded product thereof tend to deteriorate the surface appearance, such as the occurrence of silver streak due to turbulent flow and foam entrainment at the melt front. . Specific measurement conditions will be described later in Examples.
The MFR, molecular weight distribution value (Mw / Mn), propylene / ethylene random copolymer component (A-2) content and ethylene content are MFR meter, cross fractionator, Fourier transform infrared absorption spectrum analysis, gel permeation. It is a value measured by an association chromatography (GPC). The measurement conditions of main items will be described later in the examples.

(2) Production The production method of the propylene / ethylene block copolymer (A) used in the present invention is not particularly limited, and can be produced, for example, by the method shown below.
(I) Polymerization reactor The polymerization reactor is not particularly limited in shape and structure, but is generally used for a tank with a stirrer generally used in slurry polymerization and bulk polymerization, a tube reactor, and gas phase polymerization. And a horizontal reactor having a stirring blade. In the present invention, a horizontal reactor having a stirring blade is preferable, and it is more preferable to use two or more connected reactors as shown in FIG.

(Ii) Polymerization catalyst The total amount of the polymerization catalyst is preferably present at the start of the polymerization, and is preferably involved in the polymerization from the beginning of the polymerization, and it is preferable not to add a new catalyst after the start of the polymerization. In this case, deterioration of the powder properties and gel generation can be suppressed.
The kind of the polymerization catalyst is not particularly limited, and a known catalyst can be used. For example, a so-called Ziegler-Natta catalyst or a metallocene catalyst (for example, disclosed in JP-A-5-295022) in which a titanium compound and organic aluminum are combined can be used.
Here, for example, an organoaluminum compound can be used as a promoter.
In addition, various polymerization additives for the purpose of improving stereoregularity, controlling particle properties, controlling soluble components, controlling molecular weight distribution, and the like can be used for the catalyst. Examples thereof include organic silicon compounds such as diphenyldimethoxysilane and tert-butylmethyldimethoxysilane, ethyl acetate, and butyl benzoate.

(Iii) Polymerization format and polymerization solvent As the polymerization format, slurry polymerization using an inert hydrocarbon such as hexane, heptane, octane, benzene or toluene as a polymerization solvent, bulk polymerization using propylene itself as a polymerization solvent, Gas phase polymerization in which propylene is polymerized in a gas phase state is possible. Moreover, it is also possible to carry out by combining these polymerization formats.
For example, the polymerization of the propylene polymer portion is performed by bulk polymerization, the polymerization of the propylene / ethylene random copolymer portion is performed by gas phase polymerization, or the polymerization of the propylene polymer portion is performed by bulk polymerization followed by gas phase polymerization. Examples of the polymerization of the propylene / ethylene random copolymer portion include gas phase polymerization.

(Iv) Polymerization pressure In the polymerization of the present invention, the polymerization pressure is not particularly limited, and can be constant or can be changed as needed. Usually, the relative pressure with respect to atmospheric pressure is 0.1 to 5 MPa, preferably about 0.3 to 3.5 MPa. When two horizontal reactors having stirring blades are connected and used as shown in FIG. 2, the first polymerization step is 1.0 to 3.0 MPa, and the second polymerization step is 1.0 to 3.0 MPa. It is preferable that However, the polymerization pressure should not be set higher than the vapor pressure of propylene at the polymerization temperature.

(V) Polymerization temperature In this invention, although it does not specifically limit regarding polymerization temperature, Usually, 20-100 degreeC, Preferably it selects from the range of 40-80 degreeC. This polymerization temperature may be the same or different at the start of polymerization and at the end of polymerization. When two horizontal reactors having stirring blades are connected and used as shown in FIG. 2, the first polymerization step may be 40 ° C. to 80 ° C., and the second polymerization step may be 30 ° C. to 80 ° C. preferable.

(Vi) Polymerization time In this invention, although superposition | polymerization time is not specifically limited, It is normally implemented in 30 minutes-10 hours. In general, the production of the propylene polymer portion is typically 30 minutes to 5 hours for gas phase polymerization, 30 minutes to 2 hours for bulk polymerization, and 2 to 8 hours for slurry polymerization, and the propylene / ethylene random copolymer portion. The standard is 1 to 3 hours for gas phase polymerization, 20 minutes to 1 hour for bulk polymerization, and 1 to 3 hours for slurry polymerization. When two horizontal reactors having stirring blades are connected and used as shown in FIG. 2, the first polymerization step may be 30 minutes to 4 hours, and the second polymerization step may be 30 minutes to 3 hours. preferable.

The propylene polymer component (A-1) is preferably a propylene homopolymer from the viewpoint of the rigidity of the foamable polypropylene resin composition, but from the viewpoint of moldability, the propylene polymer component (A-1) is a co-polymer of propylene and a small amount of a comonomer. It may be a polymer. Specifically, in the copolymer, for example, α other than propylene such as ethylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 4-methyl 1-pentene and the like. -Comonomer units corresponding to one or more comonomers selected from the group consisting of vinyl compounds such as olefins, styrene, vinylcyclopentene, vinylcyclohexane and vinylnorbornane can be included, preferably in a content of 5% by weight or less. Two or more of these comonomers may be copolymerized. The comonomer is preferably ethylene and / or 1-butene, most preferably ethylene.
Here, the content of the comonomer unit is a value determined by infrared spectroscopy (IR).
Following the polymerization of the propylene polymer portion, the propylene / ethylene random copolymer portion is polymerized.
Various products are commercially available as propylene / ethylene block copolymers that satisfy these specified values, and these commercially available products may be used as the propylene / ethylene block copolymer (A) in the present invention. .

(3) Blending ratio The blending ratio of various components in the foamable polypropylene resin composition of the present invention is based on 100 parts by weight of propylene / ethylene block copolymer (A). In addition, (A) can also use 2 or more types together, In that case, it is based on the total amount used.

2. Filler (B)
The filler (B) used in the present invention is an inorganic or organic filler. (B) is a foamable polypropylene-based resin composition and its foamed molded article, with improved solid feeling (rigidity), improved dimensional stability (reduced linear expansion coefficient), improved physical properties such as rigidity, surface appearance・ Contributes to the improvement of foaming ratio and environmental adaptability.

(1) Kind, shape, etc. Specific examples of the filler (B) include, for example, as an inorganic filler, oxides such as silica, diatomaceous earth, barium ferrite, beryllium oxide, pumice, and pumice balun, aluminum hydroxide, hydroxide Magnesium, hydroxides such as basic magnesium carbonate, carbonates such as calcium carbonate, magnesium carbonate, dolomite, dawsonite, sulfates or sulfites such as calcium sulfate, barium sulfate, ammonium sulfate, calcium sulfite, talc, clay, mica, Glass fibers, glass balloons, glass beads, silicates such as calcium silicate, wollastonite, montmorillonite, bentonite, carbons such as carbon black, graphite, carbon fiber, carbon hollow sphere, molybdenum sulfide, boron fiber, boron Zinc acid, metaphor Examples thereof include barium oxalate, calcium borate, sodium borate, basic magnesium sulfate fiber, potassium titanate fiber, aluminum borate fiber, calcium silicate fiber, calcium carbonate fiber, and various metal fibers.
On the other hand, examples of the organic filler include shell fibers such as fir shells, wood powder, cotton, jute, paper strips, cellophane pieces, aromatic polyamide fibers, cellulose fibers, nylon fibers, polyester fibers, polypropylene fibers, and various synthetic fibers. And thermosetting resin powder.

There is no restriction | limiting in particular about the shape of a filler (B), A thing of any shape, such as a granular form, plate shape, rod shape, fiber shape, and a whisker shape, can be used.
Among them, the plate-like, fiber-like, and whisker-like ones are easy to obtain the foamable polypropylene resin composition of the present invention and the foamed molded article thereof excellent in a balance of firmness (rigidity), dimensional stability and physical properties. It is preferable at such points.
Moreover, what is marketed as a filler for polymers can use all. These are often manufactured in the form of compressed soul, pellets (granulated), granules, chopped strands, etc., in addition to the general powder form, with improved handling convenience, etc. Either can be used. Of these, powder, compressed soul, and granule are preferable.

Among the fillers (B), at least one selected from talc, polyester fiber, whisker, glass fiber, and carbon fiber, particularly talc and polyester fiber, is foam moldability, dimensional stability, firm feeling (rigidity), It is preferable from the viewpoints that a foamable polypropylene resin composition excellent in balance between physical properties such as rigidity, scratch resistance and firmness (rigidity), and balance such as economy, and a foamed molded product thereof can be easily obtained. Here, for example, a blend of a plurality of different fibers such as a blend of polyester fiber and cotton may be used.
The whisker here refers to ultrafine (approximately 2 μmφ or less, especially 1 μmφ or less) fibers such as basic magnesium sulfate fibers, potassium titanate fibers, aluminum borate fibers, calcium silicate fibers, calcium carbonate fibers, and ultrafine carbon fibers. It is a shape.

Among these, talc having an average particle size of 15 μm or less, preferably 0.5 to 10 μm, more preferably 2 to 8 μm, has foam molding properties, dimensional stability, firmness (rigidity), rigidity and other physical properties, and scratch resistance. It is preferable in that a foamable polypropylene resin composition and a foamed molded product thereof that are particularly excellent in the balance of the balance between the property and the firmness (rigidity) and the economy are easily obtained.
This average particle diameter is a value measured using a laser diffraction / scattering particle size distribution analyzer or the like, and examples of the measuring apparatus include Horiba LA-920 type. Further, talc having an average aspect ratio of 4 or more, particularly 5 or more is more preferable. The aspect ratio of talc is measured from a value measured with a microscope or the like.

  These fillers (B) are surface-treated with an organic titanate coupling agent, an organic silane coupling agent, an unsaturated carboxylic acid, or a modified polyolefin grafted with an anhydride thereof, fatty acid, fatty acid metal salt, fatty acid ester, etc. In addition, two or more types may be used in combination for surface treatment.

(2) Production The production method of these fillers (B) is not particularly limited, and is produced by various known production methods. For example, in the case of talc, a product obtained by mechanically pulverizing a product naturally produced can be obtained by classifying one or more times more precisely. Examples of the pulverizer include a jaw crusher, a hammer crusher, a roll crusher, a screen mill, a jet pulverizer, a colloid mill, a roller mill, and a vibration mill. These pulverized talcs are wetted once or repeatedly in an apparatus such as a cyclone, a cyclone air separator, a micro separator, a cyclone air separator, or a sharp cut separator to adjust to the average particle size shown in the present invention. Perform dry classification. After pulverization to a specific particle size, classification is preferably performed with a sharp cut separator.
Moreover, various commercial products can also be purchased and used as a filler (B) in this invention.

(3) Blending ratio In the present invention, the blending ratio of the filler (B) used is 1 to 10 parts by weight, preferably 1.5 to 8 parts by weight, more preferably 100 parts by weight of (A). 2 to 6 parts by weight.
If the blending ratio of (B) is less than 1 part by weight, the firmness (rigidity), dimensional stability, etc. of the expandable polypropylene resin composition and the foamed molded product may be easily lowered.
On the other hand, if it exceeds 10 parts by weight, foam moldability, scratch resistance, surface appearance and impact strength may be reduced. In addition, (B) can also use 2 or more types together.

3. Ethylene polymer (C)
The ethylene polymer (C) used in the present invention has a total MFR (190 ° C., 2.16 kg load) of (C) of 5 to 60 g / 10 minutes.
The ethylene polymer (C) has an ethylene content of 50 mol% or more in the whole (C) and does not correspond to the elastomer (E) described later.
This ethylene polymer (C) is added to the propylene / ethylene block copolymer (A) and the filler (B) together with the foaming agent (D) described later, and the foamable polypropylene resin composition of the present invention. The product and its foamed molded article have characteristics such as a particularly excellent surface appearance and scratch resistance, no sticky feel, and a high expansion ratio.

(1) Types and characteristics The types of ethylene polymer (C) used in the present invention include high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), and linear low density polyethylene ( LLDPE) (including linear medium density polyethylene (LMDPE)), very low density polyethylene (VLDPE), ethylene / α, β-unsaturated carboxylic acid ester copolymer, ethylene / α-olefin copolymer Among the polymers and polyethylene copolymers such as ethylene / vinyl ester copolymers, mention may be made of those not corresponding to the elastomer (E) described later, and it is at least one polymer selected from these. .
Among them, high-density polyethylene (HDPE), medium-density polyethylene (MDPE), and low-density polyethylene (LDPE) from the viewpoints of improving the surface appearance and scratch resistance of the foamable polypropylene resin composition and foamed molded product of the present invention. ), Or linear low-density polyethylene (LLDPE) is used alone, or two or more of these are preferably used together, and each of high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE) is used alone It is more preferable to use these in combination.

  The ethylene polymer (C) has an overall MFR (190 ° C., 2.16 kg load) of 5 to 60 g / 10 minutes, preferably 6 to 40 g / 10 minutes, more preferably 10 to 30 g / 10 minutes. . When the MFR (190 ° C., 2.16 kg load) is less than 5 g / 10 minutes, in the foamable polypropylene resin composition and the foamed molded product of the present invention, the fluidity (moldability) and the appearance of the foamed molded product are May decrease. On the other hand, if it exceeds 60 g / 10 minutes, the dispersed state of (C) in the resin composition becomes non-uniform, and the appearance, scratch resistance and impact strength of the foamed molded product are reduced. There is a risk of stickiness. The MFR (190 ° C., 2.16 kg load) value is a value measured according to JIS K6922 or K7210.

Here, the density of the ethylene polymer (C) is not particularly limited, but is usually about 0.86 to 0.97 g / cm ³ . When the density is less than 0.86 g / cm ³ , scratch resistance, rigidity, and the like may be lowered in the foamable polypropylene resin composition and the foamed molded product of the present invention.
On the other hand, if it exceeds 0.97 g / cm ³ , scratch resistance and impact strength may be reduced.
For example, when (C) is high-density polyethylene, it is usually about 0.92 to 0.97 g / cm ³ , preferably 0.94 to 0.965 g / cm ³ , more preferably 0.95 to 0. 96 g / cm ³ . When the density is less than 0.92 g / cm ³ , in the foamable polypropylene resin composition and the foamed molded article of the present invention, scratch resistance, firmness (rigidity), etc. may decrease, or sticky tactile sensation may occur. There is a risk. On the other hand, if it exceeds 0.97 g / cm ³ , scratch resistance and impact strength may be reduced.
In the case of (C) is linear low density polyethylene, is usually 0.90~0.95g / cm ^3, preferably about 0.91~0.94g / cm ^3, more preferably 0.915 ˜0.935 g / cm ³ . When the density is less than 0.90 g / cm ³ , in the foamable polypropylene resin composition and the foamed molded product of the present invention, scratch resistance, firmness (rigidity), etc. may decrease, or sticky tactile sensation may occur. There is a risk. On the other hand, if it exceeds 0.95 g / cm ³ , scratch resistance and impact strength may be reduced. The density value is a value measured according to JIS K6922 or K7112.

(2) Manufacturing The manufacturing method of the ethylene polymer (C) used for this invention is not specifically limited, For example, it can manufacture with the method shown below.
When (C) is high density polyethylene or medium density polyethylene, for example, transition metal compounds such as titanium and zirconium, Ziegler catalysts composed of magnesium compounds, Phillips catalysts typified by chromium oxide catalysts, zirconium, hafnium, titanium, etc. Using a catalyst such as a metallocene catalyst having at least one cyclopentadienyl group or a substituted cyclopentadienyl group as a transition metal compound, and in a process such as a gas phase method, a solution method, a high pressure method, a slurry method, Alternatively, it is produced by (co) polymerizing ethylene and a small amount of propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene or other α-olefin.
When (C) is a linear low density polyethylene, for example, using a catalyst such as the Ziegler catalyst, the Phillips catalyst, or the metallocene catalyst, a gas phase method, a solution method, a high pressure method, a slurry method, etc. In this process, ethylene and an α-olefin such as propylene, 1-butene, 1-hexene, 4-methyl-1-pentene and 1-octene are copolymerized. The α-olefin may be used alone or in combination of two or more.

When (C) is low-density polyethylene, for example, ethylene or ethylene and a small amount of propylene, 1-butene, 1) in a process such as high-pressure radical polymerization using a radical generator such as peroxide as a polymerization initiator. -Manufactured by (co) polymerizing with α-olefin such as hexene, 4-methyl-1-pentene, 1-octene.
Moreover, when (C) is an ultra-low density polyethylene, it manufactures by the same method as the case of the said linear low density polyethylene, for example.
Moreover, various products are commercially available as ethylene polymers, and those satisfying the conditions stipulated in the present application may be purchased and used as the ethylene polymer (C) of the present invention.

(3) Blending Ratio In the present invention, the blending ratio of the ethylene polymer (C) used is 1 to 15 parts by weight, preferably 2 to 100 parts by weight of the propylene / ethylene block copolymer (A). 10 parts by weight, more preferably 3 to 8 parts by weight.
When the blending ratio of (C) is less than 1 part by weight, the surface appearance, scratch resistance, impact strength, etc. of the foamable polypropylene resin composition and the foamed molded product thereof may be lowered, while the blending ratio is If it exceeds 15 parts by weight, a sticky tactile sensation may occur or a firm feeling (rigidity) may be reduced. In addition, (C) can also use 2 or more types together.

4). Foaming agent (D)
The foaming agent (D) used in the present invention is a chemical foaming agent, a physical foaming agent, a microcapsule, or the like. In the foamable polypropylene resin composition and the foamed molded product thereof, the foaming ratio is increased and a good surface appearance is expressed. It has a function to make it.

(1) Types, functions, etc. Examples of the type of foaming agent (D) include chemical foaming agents, physical foaming agents, and microcapsules. However, a chemical foaming agent is preferable because the surface appearance and foam moldability of the foam molded article are often good.
Examples of the chemical foaming agent include inorganic chemical foaming agents such as sodium bicarbonate, sodium carbonate, ammonium bicarbonate, ammonium carbonate, and ammonium nitrite, azodicarbonamide (ADCA), N, N′-dinitrosopentamethylenetetramine. And organic chemical blowing agents such as benzenesulfonyl hydrazide and 4,4′-diphenyldisulfonyl azide.

  These chemical foaming agents include organic acids such as citric acid that promote gas generation and sodium citrate Organic acid metal salts and the like can be used and added together, and inorganic fine particles such as talc and lithium carbonate can be added as a nucleating agent.

As the chemical foaming agent, an inorganic type is preferable because various molding machines such as a normal injection molding machine can be used safely and uniform fine bubbles are easily obtained in the molded body.
As described above, the chemical foaming agent includes various inorganic and organic types, and preferable examples include sodium bicarbonate, citric acid, sodium citrate, and a mixture of two or more of these. Examples include sodium bicarbonate, a combination of sodium bicarbonate and sodium citrate, and a combination of sodium bicarbonate and citric acid.

These chemical foaming agents are, for example, processed into particles having an average particle diameter of 1 to 100 μm, and at the time of foam molding, propylene / ethylene block copolymer (A), filler (B) and ethylene polymer (C), or ( A), (B), (C) and the elastomer (E) described later are kneaded, mixed with a granulated material, etc., and then mixed, and then supplied to various molding machines such as injection molding machines, When molding, it is injected from the middle of a cylinder of an injection molding machine or decomposes in the cylinder or the like to generate a gas such as carbon dioxide.
In addition, the chemical foaming agent is used after granulating as a master batch based on a polyolefin-based resin from the viewpoints of handleability, storage stability, dispersibility in (A) and (C), etc. You can also. Thereby, contamination of the hopper of the molding machine and adhesion of powder to the surface of the molded body can be suppressed. In this case, it is preferably used as a master batch of polyolefin resin having a concentration of 10 to 50% by weight.
Alternatively, the chemical foaming agent may be added once and the chemical foaming agent may be decomposed by pelletization, or the chemical foaming agent having a high concentration may be decomposed in advance and the residue may be added. The chemical foaming agent decomposes in the cylinder of the molding machine, and the foaming residue can become the foam nucleating agent.

Examples of the physical foaming agent include inert gas, low-boiling organic solvent vapor, halogen-based inert solvent vapor, and air.
Examples of the inert gas include carbon dioxide, nitrogen, argon, helium, neon, and astatine. Examples of the low boiling point organic solvent vapor include methanol, ethanol, propane, butane, and pentane. Examples of the halogen-based inert solvent vapor include dichloromethane, chloroform, carbon tetrachloride, chlorofluorocarbon, nitrogen trifluoride, and the like. Among these, since it is not necessary to make steam, it is inexpensive, environmental pollution, and the risk of fire is extremely low, it is preferable to use an inert gas, among which carbon dioxide, nitrogen, argon, helium are preferable, Carbon dioxide and nitrogen are more preferable.
Furthermore, the physical foaming agent is preferably in a supercritical state, which has the advantage of facilitating gas melting into the resin. Therefore, it is particularly preferred that the physical blowing agent is carbon dioxide in the supercritical state and / or nitrogen in the supercritical state.
Physical foaming agents can be used in propylene / ethylene block copolymers (A) and ethylene polymers (C) in various molding machines such as cylinders of injection molding machines, or (A), fillers (B) and (C), Kneaded with the elastomer (E) described later, granulated product, etc., injected as a gas or supercritical fluid, dispersed or dissolved, foamed by injection into the mold and release of pressure. It functions as an agent.

Microcapsules are obtained by encapsulating a foaming agent (expansion agent) in a shell made of various thermoplastic resins. Examples of the blowing agent (swelling agent) include specific freons such as trichlorofluoromethane, dichlorofluoromethane, and dichlorofluoroethane, alternative freons, hydrocarbons such as n-pentane, isopentane, isobutane, and petroleum ether, Examples thereof include chlorinated hydrocarbons such as methyl chloride, methylene chloride, and dichloroethylene. The average particle size of the microcapsule foaming agent is usually 2 to 50 μm.
These microcapsules are usually kneaded with propylene / ethylene block copolymer (A) and ethylene polymer (C) or with (A), fillers (B) and (C), and elastomer (E) described later. After being mixed in advance with a granulated product or the like, it is supplied to various molding machines such as an injection molding machine and used.

  In the foamable polypropylene resin composition and the foamed molded product thereof, (D) is a chemical foaming agent and a physical component in order to improve the surface appearance of the foamed molded product and to further increase the expansion ratio. It is preferable to use a foaming agent in combination, and it is more preferable to use an inorganic chemical foaming agent in combination with carbon dioxide gas or nitrogen as a physical foaming agent.

(2) Blending ratio If the blending ratio of the foaming agent (D) in the foamable polypropylene resin composition of the present invention is appropriately set in consideration of the type of foaming agent, the foaming ratio, the molding conditions for foam molding, and the like. Good. For example, when a chemical foaming agent is used, it is usually 0.001 to 10 parts by weight, preferably 0.01 to 8 parts by weight, more preferably 0 to 100 parts by weight of the propylene / ethylene block copolymer (A). .1 to 6 parts by weight.
The blending ratio in this case is a substantial concentration of the foaming agent. For example, when a masterbatch of the foaming agent and the polyolefin resin is used, the blending ratio is calculated based on the concentration of the foaming agent contained in the masterbatch. When the blending ratio of (D) is less than 0.001 part by weight, the foamable polypropylene resin composition may not be sufficiently foamed. On the other hand, when the blending ratio exceeds 10 parts by weight, the expandable polypropylene resin Mechanical strength such as impact strength of the composition and the foamed molded product is reduced, secondary foaming phenomenon (a phenomenon in which the surface of the foamed molded product swells in a blistering state due to excessive remaining foaming gas), and There is also a risk of economic disadvantage.

  Moreover, when using a physical foaming agent, it sets suitably by adjusting the injection pressure of the gas to be used, for example. If the gas injection pressure is insufficient or excessive, as in the case of the chemical foaming agent, the foamable polypropylene resin composition does not sufficiently foam, or the mechanical strength of the foamed molded article is low. May decrease. In addition, (D) can also use 2 or more types together.

5. Elastomer (E)
The foamable polypropylene resin composition and the foamed molded product thereof of the present invention preferably further contain an elastomer (E) for the purpose of exhibiting higher impact strength and good dimensional stability.
The elastomer (E) used in the present invention is an ethylene / α-olefin copolymer elastomer or a styrene elastomer.

(1) Types As the elastomer (E), for example, ethylene / propylene copolymer elastomer (EPR), ethylene / butene copolymer elastomer (EBR), ethylene / hexene copolymer elastomer (EHR), ethylene / octene copolymer Ethylene / α-olefin copolymer elastomer such as polymer elastomer (EOR); Ethylene / α such as ethylene / propylene / ethylidenenorbornene copolymer, ethylene / propylene / butadiene copolymer, ethylene / propylene / isoprene copolymer -Olefin-diene terpolymer elastomer; styrene-butadiene-styrene triblock copolymer elastomer (SBS), styrene-isoprene-styrene triblock copolymer elastomer (SIS), styrene-ethylene Rene copolymer elastomer (SEB), Styrene-ethylene-propylene copolymer elastomer (SEP), Styrene-ethylene-butylene-styrene copolymer elastomer (SEBS), Styrene-ethylene-butylene-ethylene copolymer elastomer (SEBC) ), Hydrogenated styrene-butadiene elastomer (HSBR), styrene-ethylene-propylene-styrene copolymer elastomer (SEPS), styrene-ethylene-ethylene-propylene-styrene copolymer elastomer (SEEPS), styrene-butadiene-butylene- Styrene copolymer elastomer (SBBS), partially hydrogenated styrene-isoprene-styrene copolymer elastomer, partially hydrogenated styrene-isoprene / butadiene-styrene copolymer elastomer, etc. Examples include lene elastomers and hydrogenated polymer elastomers such as ethylene-ethylene / butylene-ethylene copolymer elastomers (CEBC).

Among these, when the ethylene / octene copolymer elastomer (EOR) or the ethylene / butene copolymer elastomer (EBR) is used alone or in combination, the foamable polypropylene resin composition of the present invention and the foam molding thereof are used. In the body, the impact strength and the dimensional stability are more preferable, the surface appearance and the scratch resistance are good, there is no sticky feeling, and the economy tends to be excellent.
Further, when an ethylene / octene copolymer elastomer (EOR) or an ethylene / butene copolymer elastomer (EBR) is used alone, or both of these are used in combination, the MFR of the entire expandable polypropylene resin composition of the present invention ( 230 ° C., 2.16 kg load) is 40 to 300 g / 10 minutes, in the foamable polypropylene resin composition and the foamed molded product thereof, impact strength, dimensional stability, surface appearance, scratch resistance, etc. are further improved. It is more preferable from the point of being excellent, etc., more preferably 50 to 200 g / 10 min, and particularly preferably 60 to 150 g / 10 min. The MFR value is a value measured according to JIS K7210.

(2) Production An ethylene / α-olefin copolymer elastomer, an ethylene / α-olefin / diene terpolymer elastomer, and the like are produced by polymerizing each monomer in the presence of a catalyst. Examples of the catalyst include titanium compounds such as titanium halide, organoaluminum-magnesium complexes such as alkylaluminum-magnesium complexes, so-called Ziegler-type catalysts such as alkylaluminum or alkylaluminum chloride, and the like described in WO91 / 04257. The metallocene compound catalyst can be used.
As the polymerization method, polymerization can be performed by applying a production process such as a gas phase fluidized bed method, a solution method, or a slurry method.

Styrenic elastomers and hydrogenated polymer elastomers can be produced by ordinary anionic polymerization methods and polymer hydrogenation techniques.
Various products are commercially available as these elastomers, and those satisfying the desired physical properties may be purchased and used as the elastomer (E) of the present invention.

(3) Physical properties The MFR (230 ° C., 2.16 kg load) of the elastomer (E) is usually 1 to 200 g / 10 minutes, preferably 2 to 100 g / 10 minutes, more preferably 3 to 80 g / 10 minutes, 4-60 g / 10min is more preferable.
When considering the automotive parts that are the main use of the present invention, those having an MFR in the above range are excellent in surface appearance, scratch resistance and impact strength, have no sticky touch, and have a high expansion ratio. In many cases, a resin composition and a foamed molded product thereof can be obtained.

(4) Blending ratio In the present invention, the blending ratio of the elastomer (E) used is preferably 1 to 50 parts by weight, more preferably 3 parts per 100 parts by weight of the propylene / ethylene block copolymer (A). -45 parts by weight, more preferably 5-40 parts by weight. If the blending ratio of (E) is less than 1 part by weight, the impact strength and dimensional stability of the foamable polypropylene resin composition and the foamed molded product may be reduced, while the blending ratio is 50 parts by weight. If it exceeds, scratch resistance and firmness (rigidity) may be reduced. In addition, (E) can also use 2 or more types together.

6). Optional additive component (F)
In the expandable polypropylene-based resin composition of the present invention, in addition to the above (A) to (E), if necessary, the effects of the present invention can be further improved, for example, as long as the effects of the present invention are not significantly impaired. For example, an optional additive component (F) (hereinafter also simply referred to as (F)) can be blended.

Specifically, light stabilizers such as hindered amines, ultraviolet absorbers such as benzotriazoles, nucleating agents such as sorbitols, colorants such as pigments, antioxidants such as phenols and phosphoruss, nonionics Antistatic agents such as inorganic compounds, antibacterial and antifungal agents such as thiazoles, flame retardants such as halogen compounds, process oils (blending oils), plasticizers, dispersants such as organic metal salts, Lubricants such as fatty acid amides, metal inactive agents such as nitrogen compounds, nonionic surfactants, polyolefins such as polypropylene other than (A) to (E), thermoplastic resins such as polyamide and polyester, etc. Can be mentioned.
These optional additional components (F) may be used in combination of two or more, may be added to the composition, may be added to each component (A) to (E), Two or more kinds of components can be used in combination.

As light stabilizers and ultraviolet absorbers, for example, hindered amine compounds, benzotriazoles, benzophenones, and salicylates are effective in imparting and improving the weather resistance and durability of foamable polypropylene resin compositions and foamed molded products thereof. It is.
Specific examples of the hindered amine compound include a condensate of dimethyl succinate and 1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine; poly [[6- (1, 1,3,3-tetramethylbutyl) imino-1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [(2 , 2,6,6-tetramethyl-4-piperidyl) imino]]; tetrakis (2,2,6,6-tetramethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate; tetrakis ( 1,2,2,6,6-pentamethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate; bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebake Bis-2,2,6,6-tetramethyl-4-piperidyl sebacate and the like, and examples of the benzotriazole type include 2- (2′-hydroxy-3 ′, 5′-di-t-butyl) Phenyl) -5-chlorobenzotriazole; 2- (2′-hydroxy-3′-t-butyl-5′-methylphenyl) -5-chlorobenzotriazole, and the like. As the benzophenone series, 2-hydroxy- 4-methoxybenzophenone; 2-hydroxy-4-n-octoxybenzophenone and the like. Examples of salicylates include 4-t-butylphenyl salicylate; 2,4-di-t-butylphenyl 3 ′, 5′- Examples include di-t-butyl-4′-hydroxybenzoate.

In addition, as a nucleating agent, for example, inorganic, sorbitol, carboxylic acid metal salt, and organic phosphate, the foaming polypropylene resin composition and its foam molded article have rigidity, heat resistance and hardness, and scratch resistance. It is effective for imparting, improving, etc., stickiness, firmness (rigidity), and foam moldability.
Specific examples include talc; silica and the like as inorganic system, and 1,3,2,4-dibenzylidene-sorbitol; 1,3,2,4-di- (p-methyl-benzylidene as sorbitol system. ) Sorbitol; 1,3,2,4-di- (p-ethyl-benzylidene) sorbitol; 1,3,2,4-di- (2 ′, 4′-di-methyl-benzylidene) sorbitol; -P-chlorobenzylidene-2,4-p-methyl-benzylidene-sorbitol; 1,3,2,4-di- (p-propylbenzylidene) sorbitol and the like. -Hydroxy-di-pt-butylbenzoate; sodium benzoate; calcium montanate and the like. (4-t-butylphenyl) phosphate; sodium-2,2′-methylene-bis (4,6-di-t-butylphenyl) phosphate; lithium-2,2′-methylene-bis (4,6 -Di-t-butylphenyl) phosphate and the like.

In addition, as a colorant, for example, an inorganic or organic pigment, the colored appearance, appearance, texture, scratch resistance, commercial value, weather resistance and durability of the expandable polypropylene resin composition and the foamed molded product thereof. It is effective for granting and improving.
Specific examples of the inorganic pigment include titanium oxide; iron oxide (eg, bengara); chromic acid (eg, galvanized lead); molybdic acid; selenide sulfide; ferrocyanide and carbon black. A poorly soluble azo lake; a soluble azo lake; an insoluble azo chelate; a condensable azo chelate; an azo pigment such as other azo chelates; a phthalocyanine pigment such as phthalocyanine blue; a phthalocyanine green; an anthraquinone; a perinone; a perylene; Rake; quinacridone type; dioxazine type; isoindolinone type. Moreover, in order to make a metallic tone or a pearl tone, an aluminum flake; a pearl pigment can be contained. Moreover, dye can also be contained.

In addition, as an antioxidant, for example, antioxidants such as phenolic, phosphorus and sulfur are heat-resistant stability, processing stability, heat aging resistance, etc. of foamable polypropylene resin compositions and foamed molded products thereof. It is effective for imparting, improving, etc.
Examples of phenolic antioxidants include 2,6-di-t-butyl-4-methylphenol; tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl). Propionate] -methane; tris (3,5-di-t-butyl-4-hydroxyphenyl) isocyanurate and the like.
Examples of phosphorus antioxidants include distearyl pentaerythritol diphosphite; tris (2,4-di-t-butylphenyl) phosphite; tris (2-t-butyl-4-methylphenyl) phosphite. For example, fights.
Moreover, as a sulfur type antioxidant, distearyl thiodipropionate etc. are mentioned, for example.

  Further, as the antistatic agent, for example, a nonionic or cationic antistatic agent is effective for imparting and improving the antistatic property of the foamable polypropylene resin composition and the foamed molded product thereof. Specific examples include polyoxyethylene alkylamines; polyoxyethylene alkylamides; polyoxyethylene alkylphenyl ethers; stearic acid monoglycerides; alkyldiethanolamines; alkyldiethanolamides; alkyldiethanolamine fatty acid monoesters;

[II] Method for Producing Expandable Polypropylene Resin Composition The method for producing the expandable polypropylene resin composition of the present invention includes propylene / ethylene block copolymer (A), filler (B), and ethylene polymer (C ) And a foaming agent (D), and in some cases, the elastomer (E) and the optional additive component (F) are blended in the above blending ratio, and then dry blended such as by dusting or hand blending, V blender Various blenders such as tumbler mixers, mixing methods using mixers, etc., single-screw extruder, twin-screw extruder, Banbury mixer, roll mixer, Brabender plastograph, kneader, etc.・ Granulation method and each of the above components separately (or partially blended) A method of directly supplying to any of various molding machines can be mentioned.

  When selecting a melting / kneading / granulating method, it is usually preferable to melt, knead / granulate using a twin screw extruder. In this melting, kneading and granulating, the blend of (A), (B), (C) and (D) (in some cases (A) to (F), etc.) is simultaneously melted, kneaded and granulated. Each component may be divided in order to improve performance. For example, a part of (A) and (B) is first melted, kneaded and granulated, and then the remaining components are melted, kneaded and kneaded. It can also be granulated. When all or part of (D) is melted / kneaded / granulated in the foam molding step, it is melted / kneaded / granulated only with components excluding all or part of (D). .

Here, in the production of the expandable polypropylene resin composition of the present invention, for the purpose of improving the fluidity, foam moldability, surface appearance of the molded foam, scratch resistance, and expansion ratio of the resin composition. Further, a molecular weight depressant can be blended, mixed, melted, kneaded and granulated. That is, when mixing, melting, kneading and granulating a blend of (A), (B), (C) and (D) (in some cases (A) to (F), etc.) Mix, melt, knead, and granulate with appropriate amount. In this case, the foamable polypropylene resin composition can be produced only by mixing. Here, the molecular weight of (A) was lowered in advance by mixing, melting, kneading and granulating the molecular weight depressant only in (A) in advance, and (A) in which this molecular weight was lowered. It can be mixed, melted, kneaded and granulated simultaneously with the other components (B).
In addition, an appropriate amount of a molecular weight depressant is mixed with a blend of (A), (B), (C) and (D) (in some cases (A) to (F), etc.) and various molding machines such as injection molding machines. It is also possible to directly add them individually or separately.

As the molecular weight depressant, various organic peroxides and so-called decomposition (oxidation) accelerators can be used, and organic peroxides are preferred.
Examples of the organic peroxide as the molecular weight depressant include benzoyl peroxide, t-butyl perbenzoate, t-butyl peracetate, t-butyl peroxyisopropyl carbonate, 2,5-di-methyl-2,5-di- (Benzoylperoxy) hexane, 2,5-di-methyl-2,5-di- (benzoylperoxy) hexyne-3, t-butyl-di-peradipate, t-butylperoxy-3,5,5 -Trimethylhexanoate, methyl-ethylketone peroxide, cyclohexanone peroxide, di-t-butyl peroxide, dicumyl peroxide, 2,5-di-methyl-2,5-di- (t-butylperoxide Oxy) hexane, 2,5-di-methyl-2,5-di- (t-butylperoxy) hexyne-3,1,3-bi -(T-butylperoxyisopropyl) benzene, t-butylcumyl peroxide, 1,1-bis- (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis- (t -Butylperoxy) cyclohexane, 2,2-bis-t-butylperoxybutane, p-menthane hydroperoxide, di-isopropylbenzene hydroperoxide, cumene hydroperoxide, t-butyl hydroperoxide, p-cymene One or two selected from the group of hydroperoxide, 1,1,3,3-tetra-methylbutyl hydroperoxide and 2,5-di-methyl-2,5-di- (hydroperoxy) hexane The thing which consists of the above can be mentioned. However, the present invention is not limited to these.

  In the present invention, the blending amount of the molecular weight depressant is not particularly limited, but is usually about 0.005 to 0.5 parts by weight with respect to 100 parts by weight of the propylene / ethylene block copolymer (A). When the molecular weight depressant is less than 0.005 parts by weight, the effect of lowering the molecular weight is poor, and when it exceeds 0.5 parts by weight, the surface appearance of the foamed molded product deteriorates (silver streaks occur, elastomer components, etc. May cause a bleed-out phenomenon).

[III] Foam Molded Body, Method for Producing the Same, and Application There are no particular limitations on the method for producing the foam molded body in the present invention. For example, a foam molding method using the above may be used. Among these, an injection foam molding method using an injection molding machine or an injection compression molding machine is a preferable manufacturing method.
In the production of a foam molded article using the expandable polypropylene resin composition in the present invention, the injection rate in the injection foam molding and the molding shear rate in extrusion molding are not particularly limited, and are relatively small (slow) Can be set in a wide range from large to fast (fast).
That is, the expandable polypropylene resin composition of the present invention is less susceptible to turbulent flow and bubble entrainment in the melt front (resin flow tip) even under a wide range of injection rates (molding shear rate). This is because it is possible to obtain a foamed molded article having excellent surface appearance, excellent scratch resistance, no sticky touch, high expansion ratio, and a firm feeling (rigidity).

Here, for example, in an injection molding machine or an injection compression molding machine used for injection foam molding, the driving system may be hydraulic, electric, or a combination of both, but any type of molding machine can be used. . Incidentally, the injection rate in these molding machines tends to be generally wider when the injection mechanism is electrically driven than when it is hydraulic.
As a method for injection foam molding, for example, a foamable polypropylene resin composition containing at least part of a foaming agent (D) that is a chemical foaming agent in a mold cavity, and a movable mold at a pressure equal to or higher than the foaming pressure. There is a method in which after injection filling while retreating to form a skin layer, the core layer is foamed by further retracting the movable mold after filling is completed.

Also, for example, a polypropylene resin composition or a foamable polypropylene resin composition composed of components excluding all or part of the foaming agent (D), which is a chemical foaming agent, is supplied to an injection molding machine. (D) which is an agent is directly added to a molding machine in a compressed gas state or in a supercritical state, and is injected into a mold to form an injection foam molded article.
That is, the foaming polypropylene-based resin composition containing a chemical foaming agent is supplied to an injection molding machine, and at the same time, the physical foaming agent is directly controlled and introduced into the molding machine, and molding is performed by moving the movable mold backward. However, after forming the skin layer by injection filling, it can also be used in a molding method in which the movable layer is retracted to foam the core layer.

Further, for example, a mold cavity corresponding to the shape position of the foam molded body as a final product using an injection molding machine or an injection compression molding machine in which the mold is composed of a fixed mold and a movable mold capable of moving forward and backward An injection process of injecting and filling a foamed polypropylene resin composition in a molten or semi-molten state into a mold cavity having an initial mold cavity clearance (T0) smaller than the clearance (T1); A mold opening injection foaming method including a foaming process in which the movable mold is retreated (core back) to the clearance (T1) and the gap of the mold cavity is filled with the expansion pressure by the foaming agent.
This molding method is a preferred method because the foamed polypropylene resin composition and the foamed molded product thereof can exhibit the surface appearance, scratch resistance, foaming ratio and firmness (rigidity) at a high level. In the present invention, in the injection step of injecting and filling the expandable polypropylene resin composition by the molding method, it is preferable that the injection rate for the pre-foamed molded body filling volume of 100% is molded under the condition of 10 to 450% / second, Molding is more preferably performed at a rate of 20 to 300% / second, more preferably molding at a rate of 20 to 80% / second, and particularly preferably molding at a rate of 30 to 60% / second. If the injection rate is less than 10% / second, the molding (production) efficiency of the foamed molded product tends to decrease. On the other hand, if it exceeds 450% / second, the expansion ratio decreases and the generation of molding burrs ( Overfilling) and resin burn (black spots) tend to occur.
The reason why it is preferable to mold under these conditions is that, under the circumstances where it is necessary to maintain applicability to various molded product designs as described above, when molding is performed under high molding efficiency and at a high injection rate. This is because it is possible to prevent the occurrence of molding burrs and resin burns, which are likely to occur, and to express the surface appearance, scratch resistance, foaming magnification and firmness (rigidity) of the foamed molded product at an even higher level.

The foamed molded product of the present invention is obtained by a method of foam-molding the above-mentioned foamable polypropylene resin composition, and preferably has a skin layer on at least a part of the surface. The skin layer is a non-foamed layer formed on the surface of at least one side of the foamed layer.
The foamed layer preferably has an average cell diameter of 500 μm or less, more preferably 200 μm or less, and the non-foamed layer preferably has a thickness of 10 μm or more and 1000 μm or less, more preferably 100 μm or more and 500 μm or less. When the average cell diameter of the foam layer exceeds 500 μm, excellent rigidity tends not to be obtained. In addition, if the thickness of the non-foamed layer is less than 10 μm, the surface is not beautiful, and scratch resistance, firmness (rigidity) and rigidity tend to decrease, and if it exceeds 1000 μm, lightness can be obtained. May be difficult.

  Furthermore, the expansion ratio of the foamed molded product in the present invention is preferably 2 to 10 times, more preferably 2.5 to 8 times, and even more preferably 3 to 6 times. If the expansion ratio is less than 2 times, it tends to be difficult to obtain light weight. On the other hand, if the expansion ratio exceeds 10 times, a firm feeling (rigidity) or a decrease in rigidity tends to be remarkable. The expansion ratio is the ratio of specific gravity between the foamed molded product and the non-foamed molded product molded under the same conditions except that no foaming agent is added to the foamable polypropylene resin composition of the present invention, and the thickness and initial thickness of the foamed molded product. It is a value obtained from the ratio to the wall thickness.

Furthermore, in the present invention, the foamed molded product obtained by injection-foaming molding of the expandable polypropylene resin composition (black coloration, the condition of an injection rate of 50% / second with respect to a filling volume of 100% before foaming) is the surface of the foamed molded product. In particular, when the image of the plane portion surface is analyzed using a hue histogram by a scanner, the ratio of the number of pixels in the range of lightness of 100 to 255 among lightness of 256 gradations (0 to 255 gradations) is the number of pixels. 0 to 15% of the whole is preferable, 0 to 12% is more preferable, and 0 to 10% is more preferable.
When the ratio of the number of pixels exceeds 15%, the surface appearance of the foamed molded product tends to deteriorate. Here, the brightness gradation value means that the higher the value (the larger the value), the higher the whiteness degree.
Therefore, the higher the ratio of the number of pixels in the brightness range of 100 to 255 gradations, the more whitish areas such as the silver streaks, and the greater the degree of defect in the surface appearance of the foamed molded product, the more the number of pixels The lower the ratio, the better the surface appearance.
Specific measurement conditions will be described later in the Examples section.

  Applications of the foamed molded article using the expandable polypropylene resin composition of the present invention include automobile parts, household appliances such as televisions, industrial parts including electronic parts, etc., building material parts, preferably automobile parts, more preferably Includes interior and exterior parts for automobiles, more preferably automobile interior parts such as door trims, trims, ceiling materials, trunks, instrument panels, armrests, glove boxes, switch panels, pillars, consoles, and various decorative parts. It is done.

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
The evaluation methods, analysis methods, and materials used in the examples are as follows.

1. Evaluation method, analysis method (1) Surface appearance of foam molded article:
(I) Visual appearance:
Foam molded body (length 400 mm × width 200 mm × 1.5 mm thickness (initial cavity clearance)), foaming ratio = 2, injection-foam molding (black coloration, injection rate with respect to 100% filling volume before foaming = 100% / second) The appearance of the surface of the flat portion was visually observed and judged according to the steps shown below. In this case, it is determined that stages 1 and 2 have utility. The black coloring was carried out by blending 3 parts by weight of 100 parts by weight of a foamable polypropylene resin composition with a low density polyethylene-based colored masterbatch having a carbon black concentration of 30% by weight.
Stage 1: Silver streak is not observed, there is no surface dent, and the surface appearance is good.
Stage 2: Silver streak is slightly observed, but there is almost no dent on the surface, and the surface appearance is good.
Stage 3 ... Silver streaks are relatively small but clearly recognized, surface dents are also partially recognized, and the surface appearance is slightly poor.
Stage 4: Silver streaks are clearly observed, surface dents are also considerably observed, and the surface appearance is poor.
Step 5: A large number of silver streaks are clearly observed, surface dents are also observed, and the surface appearance is further poor.
Details of the molding conditions of the foamed molded product are described in the “Examples and Comparative Examples” section below.

(Ii) Ratio of the number of pixels in the high brightness area:
Foam molded body (length 400mm x width 200mm x 1.5mm) (initial cavity clearance) injection-molded (black color (same conditions as in (i) above), injection rate 50% / second or 333% / second) ), And the surface of the flat portion having a foaming ratio of 2) was subjected to image analysis using a scanner in the following manner.
Thereafter, the ratio of the number of pixels (%) in the range of lightness of 100 to 255 within the whole lightness of 256 gradations (0 to 255 gradations) was read from the histogram (n number = 5).
(A) Device Scanner: GT-9400UF (manufactured by Seiko Epson Corporation)
Image processing; Adobe Photoshop 6.0
Image analysis; free software imagJ histogram mode (b) condition scanner mode; grayscale
Capture resolution: 600 dpi
Lightness: 256 gradations (0 to 255 gradations)
Image processing; brightness +5, contrast +90

(2) Scratch resistance:
Of each formulation shown in Table 1, an injection-molded test piece (flat plate) obtained by molding a polypropylene resin composition molding material having a formulation excluding the foaming agent (D) under the conditions shown below has a size of 80 mm × 80 mm. Then, 20 scratches were made with a scratching needle (tip radius of 0.25 mm) loaded with a load of 175 g at a scratching speed of 500 mm / min and a pitch of 0.75 mm.
Thereafter, the color difference as the degree of whitening with scratches was measured with a standard light source D65 and diffuse illumination of 8 degrees using a colorimeter (SE-200 manufactured by Nippon Denshoku Industries Co., Ltd.). The smaller the color difference (ΔE), the better the scratch resistance. That is, the scratch resistance (color difference (ΔE)) is preferably less than 0.5 in applications such as the field of automobile parts.
In addition, the tendency of the evaluation result by this method (good or bad scratch resistance) has the same tendency as the scratch resistance of all the components shown in Table 1 ((A) to (D), and optionally (E)). Show.
(Molding condition)
Molding machine: Toshiba Machine Co., Ltd. injection molding machine IS170
Mold clamping force: 170 tons Mold: 120mm x 120mm x 3mm flat plate [# 540 wrinkle finish]
Cylinder temperature: 185/220/220/210 ° C (temperature at the nozzle)
Mold temperature: 40 ℃
Filling time: about 2 seconds Injection pressure: 60 MPa
Holding pressure: 55 MPa
Back pressure: 1.2 MPa (gauge pressure)
Cooling time: 20 seconds

(3) Sticky feel:
The presence or absence of “sticky tactile sensation” was determined by touching the flat surface of the foamed molded article (ii) (injection rate = 50% / second) with bare hands. Here, when there is a sticky tactile sensation, there is a possibility that restrictions on the market application of the foamed molded product become large.

(4) Maximum foaming ratio:
Set the initial cavity clearance to 1.5 mm, expand the cavity clearance after core back from 3 mm to 0.25 mm increments, and change the foaming ratio under the above injection rate = 100% / sec. (Higher magnification) to form an injection foam molded article. Thus, in the foam molded body formed under the condition of the maximum cavity clearance after the core back, which provides a good balance between the filling state and the surface appearance, it is obtained by the plate thickness / initial thickness of the foam molded body. It was.

(5) Firm feeling (rigidity):
Holds both ends (longitudinal direction) of the injection foam molded article for visual appearance observation of (i) described above, deforms it several times like bending, and feels firm (rigidity) due to the magnitude of repulsive force at the time of bending Was determined as follows.
Yes ... There is a sense of rigidity overall, and a moderate repulsive force against bending is recognized.
None… There is little rigidity and the repulsive force against bending is also small.

(6) Melt flow rate (MFR):
In accordance with JIS K7210, measurement was performed at a test temperature of 230 ° C. and a load of 2.16 kg.
The MFR is an index mainly representing moldability. For example, in injection molding, the larger the value, the better the moldability (fluidity). The sample is obtained by removing the foaming agent (D) from each formulation shown in Table 1. In addition, the tendency (large / small) of MFR in the composition excluding the foaming agent (D) is that of all the ingredients shown in Table 1 ((A) to (C) and optionally (A) to (E)). It shows the same tendency as MFR.

(7) Charpy impact strength (notched):
In accordance with JIS K7111, the measurement was performed at a measurement ambient temperature of 23 ° C. However, the composition of this test piece is one obtained by removing the foaming agent (D) from each formulation shown in Table 1. The test piece was molded using an injection molding machine (IS80G manufactured by Toshiba Machine Co., Ltd.) with a clamping pressure of 80 tons under conditions of a molding temperature of 200 ° C. and a mold temperature of 40 ° C.
Here, if the Charpy impact strength is less than 4 KJ / m ² , application to the industrial parts field or the like may be difficult.
In addition, the tendency (large / small) of the impact strength in the composition excluding the foaming agent (D) is that of all the ingredients shown in Table 1 ((A) to (C), and in some cases (A) to (E)). It shows the same tendency as impact strength.

(8) Content of propylene / ethylene random copolymer partial component (A-2) and ethylene content:
(I) Analytical device used (a) Cross fractionation device;
Diamond Instruments CFC T-100 (hereinafter abbreviated as CFC)
(B) Fourier transform infrared absorption spectrum analysis;
FT-IR, Perkin Elmer 1760X
The fixed wavelength infrared spectrophotometer attached as a CFC detector was removed, and an FT-IR was connected instead, and this FT-IR was used as a detector. The transfer line from the outlet of the solution eluted from the CFC to the FT-IR was 1 m long, and the temperature was maintained at 140 ° C. throughout the measurement. The flow cell attached to the FT-IR was one having an optical path length of 1 mm and an optical path width of 5 mmφ, and the temperature was maintained at 140 ° C. throughout the measurement.
(C) Gel permeation chromatography (GPC);
The GPC column in the latter part of the CFC was used by connecting three AD806MS manufactured by Showa Denko KK in series.

(Ii) CFC measurement conditions (a) Solvent; orthodichlorobenzene (hereinafter also referred to as ODCB)
(B) Sample concentration: 4 mg / mL
(C) Injection volume: 0.4 mL
(D) Crystallization: The temperature was lowered from 140 ° C. to 40 ° C. over about 40 minutes.
(E) Sorting method;
Fractionation temperatures at the time of temperature-raising elution fractionation were 40, 100, and 140 ° C., and the fractions were separated into three fractions in total. In addition, the elution ratio (unit:% by weight) of the component eluting at 40 ° C. or lower (fraction 1), the component eluting at 40 to 100 ° C. (fraction 2), and the component eluting at 100 to 140 ° C. (fraction 3), respectively W ₄₀ , W ₁₀₀ , and W ₁₄₀ were defined. W ₄₀ + W ₁₀₀ + W ₁₄₀ = 100. Each fractionated fraction was automatically transported to the FT-IR analyzer as it was.
(F) Solvent flow rate during elution: 1 mL / min

(Iii) Measurement conditions for FT-IR After elution of the sample solution started from GPC at the latter stage of the CFC, FT-IR measurement was performed under the following conditions, and GPC-IR data was collected for each of the above-described fractions 1 to 3. .
(A) Detector; MCT
(B) Resolution: 8 cm ⁻¹
(C) Measurement interval: 0.2 minutes (12 seconds)
(D) Integration count per measurement: 15 times

(Iv) Post-treatment and analysis of measurement results The elution amount and molecular weight distribution of the components eluted at each temperature were determined using the absorbance at 2945 cm ⁻¹ obtained by FT-IR as a chromatogram. The elution amount was standardized so that the total elution amount of each elution component was 100%. Conversion from the retention capacity to the molecular weight was performed using a standard curve prepared in advance with standard polystyrene.
The standard polystyrenes used were all the following brands manufactured by Tosoh Corporation.
F380, F288, F128, F80, F40, F20, F10, F4, F1, A5000, A2500, A1000.

A calibration curve was prepared by injecting 0.4 mL of a solution dissolved in ODCB (containing 0.5 mg / mL BHT) so that each would be 0.5 mg / mL. For the calibration curve, a cubic equation obtained by approximation by the least square method was used. For conversion to molecular weight, a general-purpose calibration curve was used with reference to “Size Exclusion Chromatography” written by Sadao Mori (Kyoritsu Shuppan). The following numerical values were used in the viscosity equation ([η] = K × M ^α ) used at that time.
(A) when creating a calibration curve using standard polystyrene;
K = 0.000138, α = 0.70
(B) During sample measurement of (A);
K = 0.000103, α = 0.78
The ethylene content distribution (distribution of ethylene content along the molecular weight axis) of each eluted component is a ratio of the absorbance of 2956 cm ⁻¹ and the absorbance of 2927 cm ⁻¹ obtained by FT-IR, and is obtained by using polyethylene, polypropylene, or ¹³ Converted to ethylene content (% by weight) using a calibration curve prepared in advance using ethylene-propylene rubber (EPR) and mixtures thereof whose ethylene content is known by C-NMR measurement, etc. Asked.

(V) Content of Propylene / Ethylene Random Copolymer Component (A-2) The content (Wc) of component (A-2) in the propylene / ethylene block copolymer (A) used in the present invention is expressed by the following formula: It is theoretically defined by (I) and is obtained by the following procedure.
Wc (% by weight) = W ₄₀ × A ₄₀ / B ₄₀ + W ₁₀₀ × A ₁₀₀ / B ₁₀₀ (I)
In the formula (I), W ₄₀ and W ₁₀₀ are elution ratios (unit:% by weight) in each of the above-described fractions, and A ₄₀ and A ₁₀₀ are actual values in the respective fractions corresponding to W ₄₀ and W _100. It is the average ethylene content (unit: wt%) of measurement, and B ₄₀ and B ₁₀₀ are the ethylene content (unit: wt%) of the component (A-2) contained in each fraction. A method for obtaining A ₄₀ , A ₁₀₀ , B ₄₀ , and B ₁₀₀ will be described later.

The meaning of the formula (I) is as follows.
That is, the first term on the right side of formula (I) is a term for calculating the amount of component A-2 contained in fraction 1 (portion soluble at 40 ° C.). When fraction 1 contains only component A-2 and no propylene polymer component (A-1), W ₄₀ contributes to the content of component (A-2) derived from fraction 1 in the whole. However, since fraction 1 also contains components derived from component (A-2) in addition to components derived from component (A-2) (components with extremely low molecular weight and atactic polypropylene), Need to be corrected. Therefore, by multiplying W ₄₀ by A ₄₀ / B ₄₀ , the amount derived from the component (A-2) in fraction 1 is calculated. For example, when the average ethylene content (A ₄₀ ) of fraction 1 is 30% by weight and the ethylene content (B ₄₀ ) of the component (A-2) contained in fraction 1 is 40% by weight, 30/40 = 3/4 (that is, 75% by weight) is derived from the component (A-2), and 1/4 is derived from the component (A-1). Thus, the operation of multiplying A ₄₀ / B ₄₀ by the first term on the right side means that the contribution of the component (A-2) is calculated from the weight% (W ₄₀ ) of the fraction 1. The same applies to the second term on the right side, and for each fraction, the component (A-2) content is obtained by calculating and adding the contribution of the component (A-2).

(A) As described above, the average ethylene contents corresponding to fractions 1 and 2 obtained by CFC measurement were A ₄₀ and A ₁₀₀ , respectively (units are weight%).
The method for obtaining the average ethylene content will be described later.

(B) The ethylene content corresponding to the peak position in the differential molecular weight distribution curve of fraction 1 was defined as B ₄₀ (unit is% by weight). Fraction 2 is considered to be substantially defined as B ₁₀₀ = 100 in the present invention because it is considered that the rubber part is completely eluted at 40 ° C. and cannot be defined with the same definition. B ₄₀ and B ₁₀₀ are the ethylene content of the component (A-2) contained in each fraction, but it is practically impossible to determine this value analytically. This is because there is no means for completely separating and separating the component (A-1) and the component (A-2) mixed in the fraction.
Results of investigations using various models sample, B _40, when using ethylene content corresponding to the peak position of the differential molecular weight distribution curve of fraction 1, it can be well explained the effect of improving the material properties I understood. Also, B ₁₀₀ may have a crystallinity of ethylene derived chain and relative as compared to the amount of component amounts of components (A-2) contained in these fractions contained in the fraction 1 (A-2) For two reasons, the approximation to 100 is closer to the actual situation and causes almost no error in calculation. Therefore, the analysis was performed with B ₁₀₀ = 100.

(C) For the above reason, the content (Wc) of the propylene / ethylene random copolymer component (A-2) was determined according to the following formula (II).
Wc _{(wt%) = W 40 × A 40} / B 40 + W 100 × A 100/100 ... (II)
That is, W ₄₀ × A ₄₀ / B ₄₀ which is the first term on the right side of the formula (II) indicates the content (% by weight) of the component (A-2) having no crystallinity, and W ₁₀₀ which is the second term. * _A100 / 100 shows content (weight%) of the component (A-2) which has crystallinity.
_Here, the average of _{B 40} and each fraction 1 and 2 obtained by CFC measurement ethylene content _{A 40, A 100} was determined in the following manner.
Ethylene content corresponding to the peak position of the differential molecular weight distribution curve is B _40. In addition, the sum of the products of the weight ratio for each data point and the ethylene content for each data point, which is captured as data points at the time of measurement, is the average ethylene content A _{40 of} fraction 1.
The average ethylene content A _{100 of} fraction 2 was determined in the same manner.

The significance of setting the three types of fractionation temperatures is as follows.
In the CFC analysis of the present invention, the polymer having no crystallinity at 40 ° C. (for example, most of the propylene / ethylene random copolymer component (A-2) or the propylene polymer component (A-1)) It has the meaning that it is a temperature condition necessary and sufficient for fractionating only extremely low molecular weight components and atactic components). 100 ° C. means a component that is insoluble at 40 ° C. but becomes soluble at 100 ° C. (for example, component (A-2) having crystallinity due to a chain of ethylene and / or propylene, and crystals) This is a temperature that is necessary and sufficient to elute only the component (A-1) having low properties.140 ° C. is a component that is insoluble at 100 ° C. but becomes soluble at 140 ° C. (for example, component (A-1) ) In particular, a propylene / ethylene block copolymer that elutes only a highly crystalline component and a component (A-2) having an extremely high molecular weight and extremely high ethylene crystallinity) and is used for analysis. The temperature is necessary and sufficient to recover the entire amount of (A), and W ₁₄₀ does not contain any component (A-2) or is present in an extremely small amount. Since it can be ignored, component (A-2) And the ethylene content of component (A-2) were excluded from calculation.

(Vi) Ethylene content of propylene / ethylene random copolymer component (A-2):
The ethylene content of the component (A-2) in the propylene / ethylene block copolymer (A) used in the present invention was determined from the following formula using the values described above.
Ethylene content (% by weight) of component (A-2) = (W ₄₀ × A ₄₀ + W ₁₀₀ × A ₁₀₀ ) / Wc
[Wc is the ratio (% by weight) of the component (A-2) obtained previously. ]

(9) Molecular weight distribution value (Mw / Mn) of propylene polymer component (A-1):
The molecular weight distribution value (Mw / Mn) of the component (A-1) used in the present invention was determined from the molecular weight distribution curve of 140 ° C. solubles measured by gel permeation chromatography in the cross fractionation.
The method of calculating the weight average molecular weight (Mw) and the number average molecular weight (Mn) from this molecular weight distribution curve was Mw / Mn as a molecular weight distribution value (sometimes referred to as Q value) according to a known method.

(10) Linearity (existence of inflection point) of the ratio (D1 / D0 (die swell ratio)) between the diameter D1 of the extruded melt and the orifice diameter D0:
Capillary flow characteristics were measured with the following contents, and on the measurement result graph (vertical axis: D1 / D0 (die swell ratio), horizontal axis: shear rate (logarithm)), the D1 / D0 (die swell ratio). ) Plot line linearity (presence of inflection points) was determined.
(I) Equipment used: Capillary rheometer (Capillograph IC manufactured by Toyo Seiki Seisakusho Co., Ltd.)
(Ii) Orifice diameter (D0); 0.5 mm (length 5 mm, flat type)
(Iii) Barrel diameter: 9.55 mm
(Iv) Detection method of the diameter D1 of the extruded melt: Laser (v) Measurement temperature: 180 ° C.
(Vi) Piston speed; 5 to 500 mm / min (vii) Shear speed: 486 / s, 972 / s, 1945 / s, 4864 / s, 9728 / s, 19456 / s, 48641 / s
(Viii) Shear rate range for determining linearity; 400 to 10000 / s

(11) Presence or absence of melt fracture (wave phenomenon):
1 above. At the time of measuring the linearity of D1 / D0 (die swell ratio) shown in the item (10), the formation state of the extrudate having a shear rate of 400 to 10,000 / s was visually observed, and the melt fracture (ripple phenomenon) The presence or absence of occurrence was determined.

2. Material (1) Propylene / ethylene block copolymer (A)
(I) Aa: Novatec PP manufactured by Nippon Polypro Co., Ltd., grades having the following composition were used.
In the material, the ratio of the propylene / ethylene random copolymer component (A-2) to the entire propylene / ethylene block copolymer (A) is 19.9% by weight, and the total MFR (230 ° C .; 16 kg load) is 100 g / 10 minutes, MFR (230 ° C., 2.16 kg load) of the propylene polymer component (A-1) is 326 g / 10 minutes, and the molecular weight distribution value (Mw / Mn) of the same part is 2.7. The propylene-ethylene random copolymer component (A-2) has an MFR (calculated value (230 ° C., 2.16 kg load)) of 0.86 g / 10 min, and the ethylene content with respect to the total amount of the component (A-2) is 39 wt. %Met.
In addition, when the material is extruded at a shear rate of 400 to 10,000 / s in a 180 ° C. capillary rheometer, D1 / D0 (die swell ratio) calculated from the diameter D1 of the extrusion melt and the orifice diameter D0 indicates the shear rate. When the horizontal axis (logarithmic) was taken, the linearity was shown (no inflection point), and no melt fracture occurred in the extruded melt.

(Ii) Ab: A propylene / ethylene block copolymer produced by the following method was used as pellets to which an antioxidant / neutralizing agent had been added.
(A) Preparation of solid catalyst component A 10 L autoclave equipped with a stirrer was sufficiently substituted with nitrogen, and 2 L of purified toluene was introduced. To this, 200 g of Mg (OEt) ₂ and 1 L of TiCl ₄ were added at room temperature. The temperature was raised to 90 ° C. and 50 ml of di-n-butyl phthalate was introduced. Thereafter, the temperature was raised to 110 ° C. to carry out a reaction for 3 hours. The reaction product was thoroughly washed with purified toluene. Next, purified toluene was introduced to adjust the total liquid volume to 2 L. 1 L of TiCl ₄ was added at room temperature, the temperature was raised to 110 ° C., and the reaction was performed for 2 hours. The reaction product was thoroughly washed with purified toluene. Subsequently, the refined toluene was introduce | transduced and the whole liquid quantity was adjusted to 2L.
1 L of TiCl ₄ was added at room temperature, the temperature was raised to 110 ° C., and the reaction was performed for 2 hours. The reaction product was thoroughly washed with purified toluene. Further, using purified n-heptane, toluene was replaced with n-heptane to obtain a solid component slurry. A portion of this slurry was sampled and dried. As a result of analysis, the Ti content of the solid catalyst component was 2.7% by weight.
Next, a 20 L autoclave equipped with a stirrer was sufficiently replaced with nitrogen, and 100 g of the solid component slurry was introduced as a solid component. Purified n-heptane was introduced to adjust the solid component concentration to 25 g / L. 50 ml of SiCl ₄ was added and a reaction was performed at 90 ° C. for 1 hr. The reaction product was thoroughly washed with purified n-heptane.
Thereafter, purified n-heptane was introduced to adjust the liquid level to 4 L. To this, 30 ml of dimethyldivinylsilane, 30 ml of diisopropyldimethoxysilane, and 80 g of triethylaluminum diluted n-heptane as triethylaluminum were added and reacted at 40 ° C. for 2 hours. The reaction product was thoroughly washed with purified n-heptane, and a portion of the resulting slurry was sampled and dried. As a result of analysis, the solid catalyst component contained 1.2% by weight of Ti and 8.8% by weight of diisopropyldimethosisilane.

Using the solid catalyst component obtained above, prepolymerization was performed by the following procedure. Purified n-heptane was introduced into the slurry, and the concentration of the solid catalyst component was adjusted to 20 g / L.
After the slurry was cooled to 10 ° C., 10 g of a triethylaluminum diluted n-heptane solution was added as triethylaluminum, and 280 g of propylene was supplied over 4 hours.
After the supply of propylene was completed, the reaction was further continued for 30 minutes. Next, the gas phase was sufficiently replaced with nitrogen, and the reaction product was thoroughly washed with purified n-heptane. The obtained slurry was extracted from the autoclave and vacuum dried to obtain a solid catalyst component. This solid catalyst component contained 2.5 g of polypropylene per 1 g of the solid catalyst component. As a result of analysis, the portion of the solid catalyst component excluding polypropylene contained 1.0% by weight of Ti, 17.5% by weight of Mg, and 8.2% by weight of diisopropyldimethosisilane.

(A) Polymerization The polymerization method will be described with reference to the flow sheet shown in FIG. In the horizontal polymerization vessel 10 (L / D = 3.7, internal volume 100 liters) 10 of the first polymerization step having a stirring blade, 0.31 g / hr of the above-mentioned prepolymerized solid catalyst component and triethylaluminum as the organic aluminum compound were added. It supplied continuously so that Al / Mg molar ratio might be set to 5 with respect to Mg in a solid catalyst component. While maintaining the conditions of a reaction temperature of 70 ° C., a reaction pressure of 2.2 MPa, and a stirring speed of 35 rpm, hydrogen gas was added so that the hydrogen concentration in the gas phase in the polymerization vessel 10 was maintained at a hydrogen / propylene molar ratio of 0.10. The MFR of the first stage polymer was adjusted by continuously supplying from the circulation pipe 4.
The reaction heat was removed by the vaporization heat of the raw material liquefied propylene supplied from the pipe 17. The unreacted gas discharged from the polymerization vessel 10 was cooled and condensed outside the reactor system through the pipe 13 and refluxed to the polymerization vessel 10 through the pipe 17.
The produced first-stage polymerization polymer was continuously extracted from the polymerization vessel 10 through the pipe 32 so that the retained level of the polymer was 50% by volume of the reaction volume, and supplied to the polymerization vessel 20 in the second polymerization step. . At this time, a part of the polymer was intermittently collected from the pipe 32 and used as a sample for measuring the polymer yield per unit weight of MFR and catalyst. The polymer yield per catalyst unit weight was calculated from the Mg content in the polymer measured by inductively coupled plasma emission spectroscopy (ICP method) (first polymerization step).

A propylene polymer from the first stage polymerization tank and an ethylene-propylene mixed gas are continuously supplied from a first stage polymerization tank and a pipe 6 to a horizontal polymerization vessel 20 (L / D = 3.7, internal volume 100 liters) having a stirring blade, Copolymerization of ethylene and propylene was performed. The reaction conditions are agitation speed of 25 rpm, temperature of 60 ° C., pressure of 2.0 MPa, in order to adjust the ethylene content in the ethylene / propylene copolymer and the molecular weight of the ethylene / propylene copolymer, The composition was adjusted to an ethylene / propylene molar ratio of 0.35 and a hydrogen / ethylene molar ratio of 0.12. Oxygen was supplied from the pipe 7 as a polymerization activity inhibitor for adjusting the polymerization amount of the propylene-ethylene copolymer.
The reaction heat was removed by the heat of vaporization of the raw material liquefied propylene supplied from the pipe 27. The unreacted gas discharged from the polymerization vessel 20 was cooled and condensed outside the reactor system through the pipe 23 and refluxed to the polymerization vessel 20. The propylene / ethylene block copolymer produced in the polymerization step was continuously withdrawn from the polymerization vessel 20 through the pipe 39 so that the retained level of the polymer was 50% by volume of the reaction volume. The production rate of the propylene / ethylene block copolymer was 11.2 / hr (second polymerization step).

  In the material (polymer), the ratio of the propylene / ethylene random copolymer component (A-2) to the entire propylene / ethylene block copolymer (A) was 13.5% by weight, and the total MFR (230 ° C.) of (A) , 2.16 kg load) is 111 g / 10 minutes, MFR (230 ° C., 2.16 kg load) of the propylene polymer component (A-1) is 195 g / 10 minutes, and the molecular weight distribution value (Mw / Mn) of the same part is 2.9, the MFR (calculated value) of the component (A-2) is 2.99 g / 10 minutes, the ethylene content with respect to the total amount of the component (A-2) is 40.7% by weight, and the D1 in the capillary rheometer measurement / D0 (die swell ratio) showed linearity (no inflection point) as described above, and no melt fracture occurred.

(Iii) Ac: Nippon Polypro's Newcon, 100 parts by weight of grade having the composition shown below, 0.13 1,3-bis- (t-butylperoxyisopropyl) benzene as a molecular weight depressant A blended part by weight and kneaded granulated (using a single screw extruder, kneading temperature 210 ° C.) was used.
The composition of the grade was such that the proportion of the propylene / ethylene random copolymer component (A-2) to the entire propylene / ethylene block copolymer (A) was 26.1% by weight, and the total MFR (230 ° C., 2.16 kg load) is 30 g / 10 minutes, and the ethylene content with respect to the total amount of component (A-2) is 41.4% by weight.
The kneaded and granulated material has a component (A-2) ratio of 25.5% by weight to the total of (A), (A) MFR (230 ° C., 2.16 kg load) of the whole is 130 g / 10 min, propylene weight The MFR (230 ° C., 2.16 kg load) of the combined component (A-1) is 420 g / 10 minutes, the molecular weight distribution value (Mw / Mn) of the same part is 2.3, and the MFR (calculation of the component (A-2)) Value) is 4.2 g / 10 minutes, the ethylene content with respect to the total amount of component (A-2) is 41.2% by weight, and the D1 / D0 (die swell ratio) in the capillary rheometer measurement is linear as described above. (No inflection point) and no melt fracture occurred.

(Iv) Ad: 80 parts by weight of Nippon Polypropylene Newcon, the same as that used in (iii) Ac above, and 20 weights of the composition shown below in Nippon Polypro Newcon As a molecular weight depressant, 0.05 part by weight of 1,3-bis- (t-butylperoxyisopropyl) benzene was blended in 100 parts by weight of the mixture of parts, and kneading granulation (using a single screw extruder, kneading temperature 210). ℃) was used.
The composition of the grade (using 20 parts by weight) was such that the proportion of the propylene / ethylene random copolymer component (A-2) to the entire propylene / ethylene block copolymer (A) was 52.1% by weight, and the whole (A) MFR (230 ° C., 2.16 kg load) was 1 g / 10 min, and the ethylene content relative to the total amount of component (A-2) was 39.3 wt%.
In the kneaded and granulated material, the ratio of the component (A-2) to the whole (A) is 31.6% by weight, the whole MFR (230 ° C., 2.16 kg load) is 67 g / 10 min, The MFR (230 ° C., 2.16 kg load) of the combined component (A-1) is 375 g / 10 min, the molecular weight distribution value (Mw / Mn) of the same part is 2.6, and the MFR (calculation) of the component (A-2) Value) is 1.64 g / 10 min, the ethylene content with respect to the total amount of the component (A-2) is 40% by weight, and the D1 / D0 (die swell ratio) in the capillary rheometer measurement shows linearity in the same manner as described above. There was no melt fracture (no inflection point).

(V) Ae: (iii) 80 parts by weight of Newcon grade made by Nippon Polypro Co., Ltd., the same as that used in A-c, and (iv) the same as that used in A-d As a molecular weight depressant, 0.1 parts by weight of 1,3-bis- (t-butylperoxyisopropyl) benzene is blended with 100 parts by weight of a mixture of 20 parts by weight of Nippon Polypro's Newcon grade and kneaded. Grains (single screw extruder use, kneading temperature 210 ° C.) were used.
In the kneaded and granulated material, the proportion of the propylene / ethylene random copolymer component (A-2) to the entire propylene / ethylene block copolymer (A) is 33.9% by weight, and the total MFR (230 ° C.) is (A). , 2.16 kg load) is 110 g / 10 min, propylene polymer component (A-1) MFR (230 ° C., 2.16 kg load) is 1146 g / 10 min, and the molecular weight distribution value (Mw / Mn) of the same part is 2.5, MFR (calculated value) of component (A-2) is 1.14 g / 10 min, ethylene content with respect to the total amount of component (A-2) is 40.6% by weight, and said D1 in the capillary rheometer measurement / D0 (die swell ratio) showed linearity (no inflection point) as described above, and no melt fracture occurred.

(Vi) Af: 1,3-bis- (t-butyl) as a molecular weight depressant in 100 parts by weight of Nippon Polypro's Newcon grade same as that used in (iv) Ad Peroxyisopropyl) benzene was blended in 0.26 parts by weight and kneaded and granulated (using a single screw extruder, kneading temperature 210 ° C.).
In the kneaded and granulated material, the proportion of the propylene / ethylene random copolymer component (A-2) to the entire propylene / ethylene block copolymer (A) is 51.3% by weight, and the total MFR (230 ° C.) is (A). , 2.16 kg load) is 50 g / 10 minutes, MFR (230 ° C., 2.16 kg load) of the propylene polymer component (A-1) is 298 g / 10 minutes, and the molecular weight distribution value (Mw / Mn) of the same part is 2.1, MFR (calculated value) of component (A-2) is 9.3 g / 10 min, ethylene content with respect to the total amount of component (A-2) is 39% by weight, and the D1 / D0 in the capillary rheometer measurement The (die swell ratio) showed linearity as described above (no inflection point), and no melt fracture occurred.

(Vii) Ag: A propylene / ethylene block copolymer produced by the following method was used as pellets to which an antioxidant / neutralizing agent had been added.
(A) Preparation of solid catalyst component 20 liters of dehydrated and deoxygenated n-heptane and 20 liters of MgCl ₂ and Ti (O— the _{n-C 4} H _{9) 4} and 20 moles introduced and reacted for 2 hours at 95 ° C.. After completion of the reaction, the temperature was lowered to 40 ° C., and then 12 liters of methylhydropolysiloxane (20 centistokes) was introduced and reacted for 3 hours. The resulting solid component was washed with n-heptane.
Next, 5 liters of n-heptane purified in the same manner as described above was introduced into the tank using the tank equipped with a stirrer, and 3 mol of the solid component synthesized above was introduced in terms of Mg atoms. Next, 5 mol of SiCl ₄ was mixed with 2.5 liters of n-heptane, introduced into the flask at 30 ° C. for 30 minutes, and reacted at 70 ° C. for 3 hours. After completion of the reaction, washing with n-heptane was performed.
Next, 2.5 liters of n-heptane was introduced into the tank equipped with a stirrer, 0.3 mol of phthalic acid chloride was mixed, introduced at 70 ° C. for 30 minutes, and reacted at 90 ° C. for 1 hour. After completion of the reaction, washing with n-heptane was performed.
Next, 2 liters of TiCl ₄ was introduced and reacted at 110 ° C. for 3 hours. After completion of the reaction, a solid catalyst component was obtained. The titanium content of this solid catalyst component was 2.0% by weight.
Next, 8 liters of n-heptane and 400 grams of the solid catalyst component synthesized above were introduced into the tank equipped with a stirrer substituted with nitrogen, and 0.6 liter of SiCl ₄ was introduced, followed by reaction at 90 ° C. for 2 hours. After completion of the reaction, 0.54 mol of (CH ₂ ═CH) Si (CH ₃ ) ₃ , 0.27 mol of (t-C ₄ H ₉ ) (CH ₃ ) Si (OCH ₃ ) ₂ and Al (C ₂ H ₅ ) ₃ 1.5 mol was sequentially introduced and contacted at 30 ° C. for 2 hours. After completion of the contact, it was thoroughly washed with n-heptane to obtain 390 g of a solid catalyst component mainly composed of magnesium chloride. The titanium content of this product was 1.8% by weight.

(Ii) Polymerization A stainless steel autoclave with a stirrer having an internal volume of 400 liters was sufficiently substituted with propylene gas, and 120 liters of dehydrated and deoxygenated n-heptane was added as a polymerization solvent.
Next, 30 g of triethylaluminum, 147 liters of hydrogen, and 17 g of the solid component were added under the condition of a temperature of 70 ° C. After the temperature of the autoclave was raised to an internal temperature of 75 ° C., propylene was supplied so that the pressure became 0.3 MPaG, and polymerization was started. Hydrogen is supplied at a constant rate of hydrogen / propylene of 2.0 (L / kg). After 220 minutes, the introduction of propylene and hydrogen is stopped, the unreacted gas in the vessel is released to 0.03 MPaG, A coalescence part was obtained (first polymerization step).
Next, after setting the autoclave at an internal temperature of 65 ° C., 12.5 cc of n-butanol was introduced, then propylene was supplied at a constant rate of 3.5 kg / hr and ethylene was supplied at a constant rate of 1.5 kg / hr, and 90 minutes later The feed was stopped and the polymerization was terminated. The pressure was 0.03 MPaG at the start of ethylene and propylene supply, but gradually increased and was 0.1 MPaG at the stop of supply (second polymerization step).
The resulting slurry was transferred to the next tank with a stirrer, 2.5 liters of butanol was added, treated at 70 ° C. for 3 hours, and further transferred to the next tank with a stirrer to dissolve 20 g of sodium hydroxide. 100 liters of purified water was added and the mixture was treated for 1 hour, and then the aqueous layer was allowed to stand and separated to remove the catalyst residue. The slurry was treated with a centrifuge to remove heptane and treated with a dryer at 80 ° C. for 3 hours to completely remove heptane, thereby obtaining 59.6 kg of a polymer.

  In the material (polymer), the ratio of the propylene / ethylene random copolymer component (A-2) to the entire propylene / ethylene block copolymer (A) is 7.5% by weight, and the total MFR (230 ° C.) of (A) , 2.16 kg load) is 115 g / 10 min, MFR (230 ° C., 2.16 kg load) of the propylene polymer component (A-1) is 246 g / 10 min, and the molecular weight distribution value (Mw / Mn) of the same part is 3. MFR (calculated value) of component (A-2) is 0.01 g / 10 min, ethylene content with respect to the total amount of component (A-2) is 39% by weight, and the D1 / D0 (die dice) in the capillary rheometer measurement Well ratio) did not show linearity (having an inflection point) when the shear rate was taken on the horizontal axis (logarithm), and melt fracture occurred.

(Viii) Ah: In FIG. 2, 0.28 g / hr of the prepolymerized solid catalyst component supplied to the polymerization vessel 10, hydrogen / propylene mole in the gas phase in the polymerization vessel in the first polymerization step (Ii) Ab above, except that the ratio was 0.08, the hydrogen / ethylene molar ratio in the gas phase in the polymerization vessel in the second polymerization step was 0.50, and the ethylene / propylene molar ratio was 0.50. In accordance with the case of. The production rate of the propylene block copolymer was 11.8 kg / hr.
The produced propylene / ethylene block copolymer was used as pellets to which an antioxidant / neutralizing agent had been added.
The ratio of the propylene / ethylene random copolymer component (A-2) to the entire propylene / ethylene block copolymer (A) is 20% by weight, and (A) MFR (230 ° C., 2.16 kg load) ) Is 104 g / 10 min, the MFR (230 ° C., 2.16 kg load) of the propylene polymer component (A-1) is 148 g / 10 min, the molecular weight distribution value (Mw / Mn) of the same part is 5.3, the component The MFR (calculated value) of (A-2) is 25.3 g / 10 minutes, the ethylene content relative to the total amount of component (A-2) is 48.3 wt%, and the D1 / D0 (die swell in the capillary rheometer measurement) Ratio) did not show linearity (having an inflection point), and melt fracture occurred.

(Ix) Ai: In FIG. 2, 0.28 g / hr of the prepolymerized solid catalyst component supplied to the polymerizer 10, hydrogen / propylene mole in the gas phase in the polymerizer in the first polymerization step (Ii) Ab above except that the ratio was 0.105, the hydrogen / ethylene molar ratio in the gas phase in the polymerization vessel was 0.22 and the ethylene / propylene molar ratio was 0.17 in the second polymerization step. In accordance with the case of. The production rate of the propylene-based block copolymer was 11.0 kg / hr. The produced propylene / ethylene block copolymer was used as pellets to which an antioxidant / neutralizing agent had been added.
In the material, the ratio of the propylene / ethylene random copolymer component (A-2) to the entire propylene / ethylene block copolymer (A) was 9.8% by weight, and the MFR (230 ° C., 2. 16 kg load) is 136 g / 10 minutes, MFR (230 ° C., 2.16 kg load) of the propylene polymer component (A-1) is 210 g / 10 minutes, and the molecular weight distribution value (Mw / Mn) of the same part is 2.7. The MFR (calculated value) of the component (A-2) is 2.5 g / 10 minutes, the ethylene content relative to the total amount of the component (A-2) is 28% by weight, and the D1 / D0 (die swell in the capillary rheometer measurement) Ratio) showed linearity (no inflection point) and no melt fracture occurred.

(2) Filler (B)
(I) Ba: Talc (manufactured by Fuji Talc Industrial Co., Ltd., average particle size 4.5 μm, average aspect ratio 5).

(3) Ethylene polymer (C)
(I) Ca: High density polyethylene (Nippon Polyethylene, Novatec HD HJ490, MFR (190 ° C., 2.16 kg load) 20 g / 10 min, density 0.958 g / cm ³ ).
(Ii) Cb: High density polyethylene (Nippon Polyethylene, Novatec HD HY530, MFR (190 ° C., 2.16 kg load) 0.55 g / 10 min, density 0.959 g / cm ³ ).

(4) Foaming agent (D)
(I) Da: Chemical foaming agent master batch (manufactured by Eiwa Kasei Co., Ltd., Polyslen EE25C, foaming agent concentration 20%, amount of generated gas 75 to 90 ml / 2.5 g (220 ° C. constant temperature × 20 minutes)). Sodium / citric acid base, low density polyethylene base.

(5) Elastomer (E)
(I) Ea: ethylene-octene copolymer elastomer (Dow Chemical Japan, Engage 8137, MFR (230 ° C., 2.16 kg load) 30 g / 10 min, octene content 42 wt%).

3. Examples and Comparative Examples [Examples 1 to 7, Comparative Examples 1 to 11]
(1) Production of Expandable Polypropylene Resin Composition First, propylene / ethylene block copolymer (A), filler (B) and ethylene polymer (C) are blended in the proportions shown in Table 1 Only Example 7 was added with an elastomer (E)) and a tumbler, and then kneaded and granulated under the following conditions. A foaming agent (D) was blended with the granulated material at a ratio shown in Table 1 using a tumbler.
Kneading apparatus: “TEX30α” type twin screw extruder manufactured by Nippon Steel Works.
Kneading conditions: temperature = 210 ° C., screw rotation speed = 300 rpm.

(2) Molding of expandable polypropylene resin composition The expandable polypropylene resin composition produced in (1) was molded under the following conditions.
At this time, 3 parts by weight of black colored master batch (low density polyethylene base containing 30% by weight of carbon black) was blended with respect to 100 parts by weight of the total amount of the resin composition.
The test piece for evaluation of scratch resistance and Charpy impact strength is the same as that in Example 1. Evaluation method and analysis method As described in the items (2) and (7).
Injection molding machine: “α-300” manufactured by FANUC.
Mold: 400 mm long × 200 mm wide, with a plate-shaped cavity with variable thickness by adjusting the position of the movable mold, and its initial cavity clearance (T0) is 1.5 mm.
Molding conditions: cylinder temperature = 210 ° C., mold temperature = 40 ° C., injection rate = 50% / second (60 cc / second), 100% / second (120 cc / second), and 333% / second (400 cc / second), Cooling time = 30 seconds.
Molding method: The injection step is a step of injecting and filling a molten polypropylene-based resin composition into a mold cavity having an initial cavity clearance (T0) of 1.5 mm, and the foaming step is a mold cavity clearance ( T1) The mold was opened by a mold opening injection molding method, which is a step of retracting the movable mold to 3 to 5 mm and filling the voids of the mold cavity with the expansion pressure of the foaming agent. In addition, all the foaming moldings obtained by this molding method had a skin layer on the top of the foaming layer.

(3) Evaluation Performance evaluation was performed on the above molded product. The results are shown in Table 2.

4). Evaluation From the results shown in Tables 1 and 2, the foamable polypropylene resin composition having the composition shown in Examples 1 to 7 of the present invention and the foamed molded product satisfy the respective requirements in the essential constituent requirements. The foamed molded article was excellent in surface appearance and scratchability, had no sticky feel, had a high expansion ratio, had a firm feeling (rigidity), and had good MFR (moldability) and impact strength.
The flexural modulus of the resin composition excluding the foaming agent (D) of Example 1 is 1150 MPa, and the flexural modulus of the resin composition excluding the foaming agent (D) of Example 7 is 1150 MPa. The value was 860 MPa. The specimen preparation was in accordance with the Charpy impact strength, and the measurement was in accordance with JIS K7171.
If these are used, they can be significantly reduced in weight, and are excellent in recyclability and environmental adaptability. Therefore, industrial parts such as automobile parts, home appliances such as TV sets, electronic parts, etc. Has performance suitable for automotive parts such as door trims, trims, ceiling materials, trunks, instrument panels, armrests, glove boxes, switch panels, pillars, consoles, various decorative parts, etc. It was confirmed that

On the other hand, the expandable polypropylene-based resin composition having the composition shown in Comparative Examples 1 to 11 and the foamed molded product thereof are inferior to those of Examples 1 to 7 because of poor performance balance.
For example, in Comparative Example 1 in which the filler (B) and the ethylene polymer (C) were not blended, the feeling of firmness was significantly different from that in Example 1. This is considered because (B) and (C) do not satisfy the requirements of the present invention.
Moreover, the comparative example 2 which does not mix | blend ethylene polymer (C) produced the remarkable difference from Example 1 in the surface appearance and scratch resistance. This is considered because (C) does not satisfy the requirements of the present invention.
Moreover, the comparative example 3 which mix | blended (Cb) as an ethylene polymer (C) produced the remarkable difference with Example 1 in flaw resistance. This is considered because the MFR of (Cb) does not satisfy the requirements of the present invention.
Moreover, the comparative example 4 which does not mix | blend ethylene polymer (C) produced the remarkable difference from Example 2 in the surface external appearance, scratch resistance, and impact strength. This is considered because (C) does not satisfy the requirements of the present invention.
Moreover, the comparative example 5 which does not mix | blend ethylene polymer (C) produced the remarkable difference with Example 3 in flaw resistance. This is considered because (C) does not satisfy the requirements of the present invention.
Moreover, the comparative example 6 which does not mix | blend ethylene polymer (C) produced the remarkable difference with Example 4 in the flaw resistance. This is considered because (C) does not satisfy the requirements of the present invention.
Moreover, the comparative example 7 which does not mix | blend ethylene polymer (C) produced the remarkable difference with Example 5 in the flaw resistance. This is considered because (C) does not satisfy the requirements of the present invention.
Moreover, the comparative example 8 which does not mix | blend an ethylene polymer (C) produced the remarkable difference with Example 6 in flaw resistance. This is considered because (C) does not satisfy the requirements of the present invention.

Moreover, the comparative example 9 which mix | blended (Ag) as a propylene-ethylene block copolymer (A) had the remarkable difference from Example 1 in the surface appearance, scratch resistance, and impact strength. This is because (Ag) is calculated by the capillary rheometer measurement, the D1 / D0 (die swell ratio) does not show linearity (having an inflection point) when the shear rate is taken as the horizontal axis (logarithm). This is probably because the MFR of the propylene / ethylene random copolymer component (A-2) does not satisfy the requirements of the present invention.
Moreover, the comparative example 10 which mix | blended (Ah) as a propylene ethylene block copolymer (A) produced the remarkable difference from Example 1 in the surface appearance, scratch resistance, and sticky touch. This is because (Ah) is calculated by the capillary rheometer measurement, D1 / D0 (die swell ratio) does not show linearity (having an inflection point) when the shear rate is taken as the horizontal axis (logarithm). This is probably because the molecular weight distribution value (Mw / Mn) of the propylene polymer component (A-1) does not satisfy the requirements of the present invention.
Moreover, the comparative example 11 which mix | blended (Ai) as a propylene ethylene block copolymer (A) had the remarkable difference from Example 1 in the surface appearance and damage resistance. This is considered because (Ai) does not satisfy the requirements of the present invention for the ethylene content of the propylene / ethylene random copolymer component (A-2).
From the results of the above examples and comparative examples, the rationality and significance of the configuration and requirements of the present invention are demonstrated, and the superiority of the present invention over the prior art is also apparent.

  The foamable polypropylene resin composition of the present invention and the foamed molded product thereof are less likely to cause turbulent flow and foam entrainment in the melt front (resin flow front end) even under a wide range of injection rates (molding shear rate). (Silver streak) is less likely to occur, so the surface appearance and scratch resistance of the foamed molded product are excellent, there is no sticky feel, the foaming ratio is high, there is a solid feeling (rigidity), and a significant weight reduction is possible. Because of its excellent recyclability and environmental adaptability, automotive parts, household appliances such as TVs, industrial parts including electronic parts, etc., building material parts, preferably automobile parts, especially door trims, trims, ceiling materials, around trunks, Automotive interior parts such as instrument panels, armrests, glove boxes, switch panels, pillars, consoles, and various decorative parts It can be suitably used.

1, 2 Catalyst component supply piping 3, 5 Raw material propylene supply piping 4, 6 Raw material supply piping (hydrogen etc.)
7 Pipe for adding activity inhibitor 10 Polymerizer (first polymerization step)
11, 21 Gas-liquid separation tank 12, 22 Reactor upstream end 13, 23 Unreacted gas extraction pipe 14, 24 Reactor downstream end 15, 25 Condenser 16, 26 Compressor 17, 27 Raw material liquefied propylene supply line 18, 28 Raw material mixed gas supply pipe 20 Polymerizer (second polymerization step)
30 Degassing tank 32, 39 Polymer extraction piping 35 Polymer supply piping

Claims (13)

A foamable polypropylene resin composition comprising the following (A) to (D).
(A): Propylene polymer component (A-1) 40 to 97% by weight and propylene / ethylene random copolymer component (A-2) 3 to 60% by weight (provided that component (A-1) and component (A) -2) and a propylene / ethylene block copolymer having the following characteristics (i) to (iv); 100 parts by weight (B): filler; 1 -10 parts by weight (C): ethylene polymer having the following characteristics (v); 1-15 parts by weight (D): foaming agent Characteristics (i): Melt flow of the entire propylene / ethylene block copolymer (A) The rate (230 ° C., 2.16 kg load) is 50 to 300 g / 10 min.
Characteristic (ii): The propylene polymer component (A-1) has a melt flow rate (230 ° C., 2.16 kg load) of 100 to 1500 g / 10 min and a molecular weight distribution value (Mw / Mn) of 3. 5 or less.
Characteristic (iii): Propylene / ethylene random copolymer component (A-2) has a melt flow rate (230 ° C., 2.16 kg load) of 0.8 to 55 g / 10 min, and propylene / ethylene random copolymer The ethylene content with respect to the total amount of the polymer component (A-2) is 35 to 60% by weight.
Characteristic (iv): When the propylene / ethylene block copolymer (A) was extruded at a shear rate of 400 to 10,000 / s in a 180 ° C. capillary rheometer, the measured value (D1) of the diameter of the extruded melt and the orifice diameter ( The die swell ratio (D1 / D0) calculated from D0) shows linearity with respect to the common logarithm of the shear rate (having no inflection point).
Characteristic (v): Melt flow rate (190 ° C., 2.16 kg load) is 5 to 60 g / 10 min.   The expandable polypropylene resin composition according to claim 1, wherein the filler (B) is talc.   The expandable polypropylene resin composition according to claim 1 or 2, wherein the ethylene polymer (C) is high-density polyethylene and / or linear low-density polyethylene.   The foaming polypropylene resin composition according to any one of claims 1 to 3, wherein the foaming agent (D) is a chemical foaming agent.   The foaming polypropylene resin composition according to any one of claims 1 to 3, wherein the foaming agent (D) is supercritical carbon dioxide and / or supercritical nitrogen. Furthermore, the following (E) is contained, The expandable polypropylene-type resin composition as described in any one of Claims 1-5 characterized by the above-mentioned.
(E): Elastomer; 1 to 50 parts by weight   The elastomer (E) is an ethylene / octene copolymer elastomer and / or an ethylene / butene copolymer elastomer, and the melt flow rate (230 ° C., 2.16 kg load) of the entire expandable polypropylene resin composition is It is 40-300 g / 10min, The foamable polypropylene-type resin composition of Claim 6 characterized by the above-mentioned.   Furthermore, an organic peroxide is contained, The expandable polypropylene resin composition as described in any one of Claims 1-7 characterized by the above-mentioned.   A foamed molded article comprising the expandable polypropylene resin composition according to any one of claims 1 to 8.   The foamed molded article according to claim 9, wherein the foamed article has a skin layer on at least a part of the surface and has a foaming ratio of 2 to 10 times.   In an image analysis using a hue histogram by a surface scanner when the injection rate is 50% / second for an injection rate of 100% for black coloring and pre-foaming filling volume, brightness 256th The foam molded article according to claim 9 or 10, wherein the ratio of the number of pixels in the range of lightness of 100 to 255 gradations is 0 to 15% of the total number of pixels during tone (0 to 255 gradations). .   It is an object for motor vehicle parts, The foaming molding as described in any one of Claims 9-11 characterized by the above-mentioned. The method for producing a foamed molded article according to any one of claims 9 to 11, wherein the mold is composed of a fixed mold and a movable mold capable of moving forward and backward, or injection compression molding. The foaming property in a molten state or a semi-molten state is used in a mold cavity having a mold cavity clearance (T0) smaller than the mold cavity clearance (T1) corresponding to the shape position of the foamed molded product. An injection process in which a polypropylene resin composition is injected and filled under an injection rate of 10 to 450% / second with respect to a filling volume of 100% before foaming, and the movable mold is retracted to the mold cavity clearance (T1). A foam molded article produced by a mold opening injection molding method, comprising a foaming step of filling a cavity of a mold cavity with an expansion pressure by a foaming agent Manufacturing method.

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