JP5409527B2 - POLYPROPYLENE RESIN COMPOSITION, INJECTION FOAM MOLDED BODY AND PROCESS FOR PRODUCING THE SAME - Google Patents

Description

  The present invention relates to a polypropylene resin composition, an injection-foamed molded article, and a method for producing the same. More specifically, even under a low injection rate (injection speed), the surface appearance is excellent, and impact strength and injection-foaming moldability are good. The present invention relates to a polypropylene resin composition that can be significantly reduced in weight, an injection foamed molded article, 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, a polypropylene resin product that is lightweight and excellent in rigidity is provided, and one of such products is an injection foam molding of a polypropylene resin.
In the injection molding of the polypropylene-based 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 (for example, see Patent Document 1). Further, in recent years, in the automobile field, further weight reduction has been achieved in order to improve fuel efficiency (reduction of 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. It is.
However, polypropylene resin has a low melt tension (melting tension), and bubbles are easily destroyed. 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.
The term “void” as used herein refers to a coarse bubble that is generated 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 of adding a foaming agent and a crosslinking aid to polypropylene and producing a foam while cross-linking the molecules has been proposed (see, for example, Patent Document 2). .) However, even with this method, the melt tension of the polypropylene is insufficiently improved, and the odor is a problem as a result of the remaining crosslinking aid remaining in such polypropylene.

By introducing long-chain branching by irradiation, the polypropylene has a higher melt tension than ordinary linear polypropylene resins, 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 3).
It is also known that a foam molded body can be obtained by using such HMS-PP as a base resin for injection foam molding (see Patent Document 4).
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. However, it is necessary to make it 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, thermoplastic resins having a crosslinked structure tend to be difficult to be melt-processed again, and there are problems in terms of the cost of the foam, 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 5). 6)), however, as the molded body becomes larger, complicated, and thinner, an injection foam molded body that maintains a good cell shape when foamed with a high magnification and reduced thickness before foaming is obtained. It was difficult.

  In addition, by using a propylene-based multistage polymer or a polypropylene resin composition that defines the intrinsic viscosity of a propylene homopolymer component or a copolymer component, and further defines a melt index (MI) and a melt flow index (MFR), An injection-foamed molded article with excellent moldability and appearance has been obtained, but as the molded article becomes larger, more complicated, and thinner, it tends to become a short shot and the appearance is often insufficient. (For example, refer to Patent Documents 7 and 8.)

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 with a pressure higher than the foaming pressure while reversing the movable mold to form a skin layer, the movable mold is further retracted after the filling is completed. With the manufacturing method for foaming, a foamed molded article having a good surface appearance can be obtained without a special device (see, for example, Patent Document 9).
However, all of the foam-molded articles obtained by these methods have a low foaming ratio of less than 2 times, and a high foaming ratio is not obtained.

In addition, using a material composed of a linear polypropylene resin, a modified polypropylene resin exhibiting strain hardening obtained by melt-kneading a radical polymerization initiator and a conjugated diene compound, and a foaming agent, the mold is a fixed mold. A step of injecting and filling the molten mixture into a cavity having a clearance (t ₀ ) smaller than the thickness (t ₁ ) 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 And a step of completing injection filling up to a clearance corresponding to the thickness (t ₁ ) of the molded body before foaming, and a step of foaming the polypropylene resin by retracting the movable mold. Proposed injection foam moldability and surface appearance are excellent, and an injection foam molded article with a high expansion ratio is obtained (see, for example, Patent Document 10).
However, as the molded body becomes larger, more complicated, and thinner, it tends to be a short shot, and the appearance, expansion ratio, and recyclability are often insufficient.
In addition, as the injection molding machine for molding the injection foam molded body, various models such as a hydraulic drive type injection molding machine, an electric drive type injection molding machine, and an injection molding machine combining these two drive systems are used. The injection molding conditions such as the injection rate (injection speed) also vary depending on the drive system and model of the injection molding machine.

  Under these circumstances, the problems of conventional polypropylene resin compositions have been solved, and injection foam molded products that are relatively large, complicated in design, and thinned, especially injection foam molded products for automobile parts, especially trim. Excellent surface appearance, impact strength, and injection foam moldability, even under low injection rate (injection speed), which is a necessary performance for obtaining injection foam products for automobile interior parts such as roofs, ceiling materials, and trunks Therefore, there is a need for research and development on a polypropylene resin composition, an injection-foamed molded article, and a method for producing the same, which are favorable, can be significantly reduced in weight, and are excellent in recyclability.

JP-A-6-198668 Japanese Examined Patent Publication No. 45-40420 Japanese Patent Laid-Open No. 62-121704 (Japanese Patent Publication No. 7-45551) JP 2001-26032 A JP-A-8-231816 JP 2004-307665 A International Publication No. WO2005 / 097842 JP 2006-152271 A JP 2003-11190 A JP 2005-224963 A

In view of the above-mentioned problems of the prior art, the object of the present invention is that when used in an injection foam molded article, the surface appearance is excellent even under a low injection rate (injection speed), and impact strength and injection foam moldability are good. An object of the present invention is to provide a polypropylene resin composition, an injection foam molded article, and a method for producing the same, which can be significantly reduced in weight and excellent in recyclability.
Incidentally, in this specification, excellent surface appearance means that it has a good appearance while suppressing the occurrence of silver streak, and good injection foam moldability means good surface tension and a set foaming ratio. It means that the cell diameter is uniform and the cell diameter is uniform. The surface tension represents the uniformity of the surface on the surface of the molded body, and that the surface tension is good means that the entire surface of the molded body has no irregularities, and there is a partial dent or bulge. It is to indicate that there is no state. In injection foam molding, it is often experienced that the surface appearance of a molded product tends to decrease as the injection rate (injection speed) during molding decreases.

  As a result of intensive studies to solve the above problems, the present inventors have found that a linear chain having a specific property / performance comprising a linear propylene polymer portion and a linear ethylene / propylene random copolymer portion. Propylene-ethylene block copolymer (component A-1) 30 to 100% by weight and other propylene polymer (component A-2) 0 to 70% by weight polypropylene resin (component A), and a specific Propylene-ethylene block copolymer (component B), ethylene elastomer (component C), foaming agent (component D), and filler (component E) and ethylene elastomer (component C), if necessary When the elastomer (component F) was blended and the content ratios of the respective components were optimized, the first normal stress difference (N1), which shows strain hardening, even in a straight chain, in particular. 30 to 100% by weight of a linear propylene / ethylene block copolymer (component A-1) having a specific property / performance such as a ratio (N1 / SS) with a shear stress (SS) of a specific value or more, and others Specific propylene-ethylene block copolymer (component B), ethylene-based elastomer (component C), and polypropylene-based resin (component A) consisting of 0 to 70% by weight of propylene-based polymer (component A-2) When a foaming agent (component D) is blended to form a resin composition for injection foam molding, the surface appearance is excellent even under a low injection rate (injection speed), impact strength and injection foam moldability are good, The present inventors have found that a polypropylene resin composition and an injection-foamed molded product thereof that can be reduced in weight and excellent in recyclability can be obtained, and based on these findings, the present invention has been completed.

That is, according to the first invention of the present invention, it comprises a linear propylene polymer portion and a linear ethylene / propylene random copolymer portion, and the following properties (A-1-i) to (A-1) -Vi) polypropylene-based resin comprising 30 to 100% by weight of a linear propylene / ethylene block copolymer (component A-1) and 0 to 70% by weight of another propylene polymer (component A-2) (Component A), a propylene-ethylene block copolymer (Component B) having the following conditions (Bi) to (Bv), an ethylene elastomer (Component C), and a foaming agent (Component D) And the content of component B is 1 to 40% by weight with respect to 100% by weight of the total amount of components A, B and C, and the content of component C is that of components A, B and C 1 to 100% by weight of the total amount 0 polypropylene resin composition, which is a weight% is provided.
Characteristic (A-1-i): The melt flow rate (230 ° C., 2.16 kg load) of the linear propylene polymer portion is 130 g / 10 min or more.
Characteristic (A-1-ii): The ratio of the linear ethylene / propylene random copolymer portion to the entire linear propylene / ethylene block copolymer (component A-1) is 2 to 50% by weight.
Characteristic (A-1-iii): Melt flow rate (230 ° C., 2.16 kg load) exceeds 60 g / 10 min.
Characteristic (A-1-iv): Die swell ratio is 1.2 to 2.5.
Characteristic (A-1-v): Shows strain hardening in 180 ° C. extensional viscosity measurement.
Characteristic (A-1-vi): The ratio (N1 / SS) of the first normal stress difference (N1) to the shear stress (SS) in the melt viscoelasticity measurement is 1.01 or more.
Condition (Bi): 30 to 95% by weight of propylene alone or a propylene-ethylene random copolymer component (BA) having an ethylene content of 7% by weight or less in the first step using a metallocene catalyst. Propylene- obtained by sequentially polymerizing 70 to 5 wt% of a propylene-ethylene random copolymer component (BB) containing 3 to 20 wt% more ethylene than component (BA) in the process It must be an ethylene block copolymer.
Condition (B-ii): The melt flow rate (230 ° C., 2.16 kg load) is in the range of 0.5 to 100 g / 10 minutes.
Condition (B-iii): The melting peak temperature (Tm) measured by the DSC method is in the range of 110 to 150 ° C.
Condition (B-iv): The molecular weight distribution value (Mw / Mn) is in the range of 1.5-4.
Condition (Bv): In the temperature-loss tangent curve obtained by solid viscoelasticity measurement, the tan δ curve has a single peak at 0 ° C. or lower.

According to the second invention of the present invention, in the first invention, the linear propylene / ethylene block copolymer (component A-1) has an intrinsic viscosity of the linear ethylene / propylene random copolymer portion [ polypropylene resin composition _{eta] copoly} is characterized in that it is a 5.3~15dl / g is provided.
According to the third invention of the present invention, in the first or second invention, the entire linear propylene / ethylene block copolymer (component A-1) has a molecular weight distribution value (Mw / Mn) of 7 to A polypropylene-based resin composition is provided.
Furthermore, according to the fourth invention of the present invention, in any one of the first to third inventions, the linear ethylene / propylene random copolymer in the linear propylene / ethylene block copolymer (component A-1) is used. An ethylene content of the polymer part is 15 to 80% by weight based on the total amount of the linear ethylene / propylene random copolymer part, and a polypropylene resin composition is provided.

According to the fifth aspect of the present invention, in any one of the first to fourth aspects, the filler (component E) is further added in an amount of 1 part by weight based on 100 parts by weight of the total amount of the components A, B and C. A polypropylene resin composition characterized by containing ˜60 parts by weight is provided.
Furthermore, according to a sixth invention of the present invention, in the fifth invention, the filler (component E) is at least one selected from talc, polyester fiber, whisker, glass fiber or carbon fiber. A polypropylene resin composition is provided.
Furthermore, according to the seventh invention of the present invention, in any one of the first to sixth inventions, an elastomer (component F) other than the ethylene-based elastomer (component C) is further added to components A, B and C. A polypropylene resin composition characterized by containing 1 to 40 parts by weight with respect to a total amount of 100 parts by weight is provided.

According to an eighth aspect of the present invention, there is provided an injection foam molded article comprising the polypropylene resin composition according to any one of the first to seventh aspects.
Furthermore, according to the ninth aspect of the present invention, the mold is composed of a fixed mold and a movable mold capable of moving forward and backward, and more than the mold cavity clearance (T1) corresponding to the shape position of the final product. An injection step of injecting and filling a molten or semi-molten polypropylene resin composition into a mold cavity having a small mold cavity clearance (T0), and retracting the movable mold to the mold cavity clearance (T1) 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, and a method for producing an injection foam molded product made of a polypropylene resin composition, comprising a polypropylene resin composition In the injection process to inject and fill a product, molding is performed under the condition that the injection rate is 100% or more for a pre-foaming molded body filling volume of 100%. Method for producing an injection molded foam product according to the eighth invention, characterized in Rukoto is provided.

As described above, the present invention relates to a linear polypropylene resin composition and the like, and preferred embodiments include the following.
(1) In the first invention, the foaming agent (component D) comprises (i) sodium bicarbonate, sodium carbonate, ammonium bicarbonate, ammonium carbonate, ammonium nitrite, azodicarbonamide (ADCA), N, N′-di A chemical blowing agent selected from nitrosopentamethylenetetramine, benzenesulfonylhydrazide or 4,4′-diphenyldisulfonyl azide, (ii) a physical blowing agent selected from carbon dioxide, nitrogen, argon or helium, or (iii) a blowing agent (expansion) A polypropylene resin composition characterized in that it is a microcapsule encapsulating an agent.
(2) In 1st invention, the compounding quantity of a foaming agent (component D) is 0.001-10 weight part with respect to 100 weight part of total amounts of component A, B, and C in the case of a chemical foaming agent. In the case of a physical foaming agent, a polypropylene resin composition characterized in that the amount is a supercritical state.
(3) In the first invention, the linear propylene polymer portion of the linear propylene / ethylene block copolymer (component A-1) is polymerized by a multistage polymerization method, preferably a two-stage polymerization method. A polypropylene-based resin composition characterized by being:
(4) In the first invention, the linear propylene / ethylene block copolymer (component A-1) has strain hardening in 180 ° C. extensional viscosity measurement, and in 180 ° C extensional viscosity measurement, the strain rate is A polypropylene resin composition having a strain hardening degree (λmax) value of 1.0 or more at 1.0 / sec.
(5) In the eighth invention, an injection foam molded article having a foamed layer having an average cell diameter of 500 μm or less and a non-foamed layer having a thickness of 10 to 1000 μm.
(6) In the eighth aspect of the invention, an injection foam molded article having an expansion ratio of 2.0 to 10 times.

  The polypropylene resin composition and injection-foamed molded article of the present invention have excellent surface appearance, impact strength and injection-foaming moldability even under a low injection rate (injection speed) despite no cross-linking modification. It is good, can be significantly reduced in weight, and exhibits 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 can be suitably used for injection molded parts including automobile interior parts such as trims, ceiling materials, and trunks.

It is a figure which shows the elution amount and elution amount integration by temperature rising elution fractionation (TREF).

The present invention comprises 30 to 100% by weight of a linear propylene / ethylene block copolymer (component A-1, hereinafter also referred to simply as component A-1) and other propylene polymers (component A-2, Hereinafter, it is also simply referred to as component A-2.) A polypropylene resin (component A, hereinafter simply referred to as component A) consisting of 0 to 70% by weight, a specific propylene-ethylene block copolymer (component B, hereinafter referred to as component A). Simply referred to as Component B), an ethylene-based elastomer (Component C, hereinafter also simply referred to as Component C), a foaming agent (Component D, hereinafter also referred to simply as Component D), and, optionally, a filler ( Polypropylene characterized by containing each component of component E, hereinafter simply referred to as component E), and elastomers other than ethylene elastomer (component C) (component F, hereinafter also simply referred to as component F). Emissions-based resin composition and an injection molded foam product.
Hereafter, each component of a polypropylene resin composition, manufacture of a polypropylene resin composition, manufacture of an injection foaming molded object, etc. are demonstrated in detail.

[I] Components of a polypropylene resin composition Polypropylene resin (component A)
The polypropylene resin (component A) used in the polypropylene resin composition of the present invention is 30 to 100% by weight, preferably 40 to 40% linear propylene / ethylene block copolymer (component A-1) described below. 100% by weight, particularly preferably 50 to 100% by weight, and other propylene polymers (component A-2) 0 to 70% by weight, preferably 0 to 60% by weight, particularly preferably 0 to 50% by weight. It will be.
Here, when the component A-1 is less than 30% by weight, the surface appearance and the injection foam moldability of the polypropylene resin composition of the present invention and the injection foam molded article thereof are deteriorated.

1-1. Linear propylene / ethylene block copolymer (component A-1)
The linear propylene / ethylene block copolymer (component A-1) used in the polypropylene resin composition of the present invention is composed of a linear propylene polymer portion and a linear ethylene / propylene random copolymer portion. It is a linear propylene / ethylene block copolymer.
Component A-1 has the following characteristics (A-1-i) to (A-1-vi), and in the polypropylene resin composition, excellent surface appearance and high injection foam moldability (surface tension, (Foaming ratio, cell form).
Characteristic (A-1-i): Melt flow rate (hereinafter referred to as MFR) (230 ° C., 2.16 kg load) of the linear propylene polymer portion is 130 g / 10 min or more.
Characteristic (A-1-ii): The ratio of the linear ethylene / propylene random copolymer portion to the whole component A-1 is 2 to 50% by weight.
Characteristic (A-1-iii): MFR (230 ° C., 2.16 kg load) exceeds 60 g / 10 min.
Characteristic (A-1-iv): Die swell ratio is 1.2 to 2.5.
Characteristic (A-1-v): Shows strain hardening in 180 ° C. extensional viscosity measurement.
Characteristic (A-1-vi): The ratio (N1 / SS) of the first normal stress difference (N1) to the shear stress (SS) in the melt viscoelasticity measurement is 1.01 or more.

Here, the “linear” in the linear propylene polymer portion, the linear ethylene / propylene random copolymer portion or the linear propylene / ethylene block copolymer (component A-1) is methyl branched. This means that there are very few branched structures other than the structure, and this is a structure often found in ordinary polypropylene resins.
For example, it can be confirmed by ¹³ C-NMR analysis that no peak is observed at 31.5 to 31.7 ppm based on branched carbon (see Macromol. Chem. Phys. 2003, Vol. 204, page 1738).

  As described above, component A-1 exhibits strain-hardening properties even though it has a linear structure. This strain hardening property is usually said to be caused by molecular entanglement. In order to develop the strain hardening property, for example, the molecular weight of the linear propylene polymer portion and the linear propylene / ethylene random copolymer weight are used. Examples of the method include increasing the difference in molecular weight of the combined portion, and increasing the compatibility between the linear propylene polymer portion and the linear propylene / ethylene random copolymer portion.

Component A-1 not only satisfies these requirements, but also has a unique dispersion structure of the linear ethylene / propylene random copolymer portion in the linear propylene polymer portion, that is, general propylene / ethylene. Unlike the case of a block copolymer (in this case, when subjected to shearing, the ethylene / propylene random copolymer portion is rejected and aggregated at the interface of the propylene polymer portion and dispersed individually), It exhibits a kind of network-like state (that is, the linear ethylene / propylene random copolymer portion penetrates into the linear propylene polymer portion in a network shape), so that the strain hardening property is improved. It is considered to show.
In addition, by exhibiting a state that approximates a kind of network, the compatibility between the linear propylene polymer portion and the linear ethylene / propylene random copolymer portion is further enhanced, Has been considered.

  The effect of exhibiting strain-hardening is that, in the polypropylene resin composition and the injection foam molded article of the present invention, silver streaks due to foam breakage at the molten resin flow front end (flow front) at the time of injection foam molding, etc. It is difficult to occur, the surface appearance is likely to be beautiful, and an injection-foamed molded article having uniform fine cells at a high magnification is easily obtained.

  The effect of setting the ratio (N1 / SS) of the first normal stress difference (N1) to the shear stress (SS) to 1.01 or more in the melt viscoelasticity measurement is the polypropylene resin composition of the present invention. In products and injection-foamed molded products, it is easy to obtain a high-magnification foamed molded product while maintaining a good cell form, and furthermore, by improving the surface tension (pushing up the surface of the molded product appropriately), the surface appearance is improved. It is to make it more beautiful.

(1) Production The linear propylene / ethylene block copolymer (component A-1) used in the present invention can be produced by a semi-batch method using a single reactor.
Hereinafter, a single reactor is charged with a polymerization solvent, a polymerization catalyst and hydrogen, and propylene and hydrogen are continuously supplied to produce a linear propylene polymer. The reactor gas is purged once, and then propylene, ethylene The semi-batch process for producing and taking out a linear ethylene / propylene random copolymer will be described.

(I) Polymerization reactor The polymerization reactor is not particularly limited in shape and structure, but is generally used in a tank with a stirrer generally used in slurry polymerization and bulk polymerization, a tube reactor, and gas phase polymerization. Examples thereof include a fluidized bed reactor and a horizontal reactor having a stirring blade. In the polymerization method using a single reactor, polymerization is performed using one reactor selected from these throughout the polymerization process.

(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. If a new catalyst is not added after the start of polymerization, a powder with a high ratio of the ethylene / propylene random copolymer to the crystalline propylene polymer produced by the added catalyst will cause 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 organoaluminum are combined can be used. Since the intrinsic viscosity of the ethylene / propylene random copolymer portion is preferably relatively high, a Ziegler-Natta catalyst with less chain transfer during polymerization is more preferable. A Ziegler-Natta catalyst is a titanium trichloride or titanium trichloride composition obtained by reduction with organoaluminum or the like as a titanium compound and treated with an electron donating compound (for example, JP-A-47-34478). And disclosed in JP-A-58-23806 and JP-A-63-146906), and by supporting titanium tetrachloride on a carrier such as magnesium chloride. 58-157808, JP-A-58-83006, JP-A-58-5310, and JP-A-61-2218606). As these catalysts, known catalysts can be used without particular limitation.

  Moreover, an organoaluminum compound is used as a promoter. For example, trialkylaluminum such as trimethylaluminum, triethylaluminum and triisobutylaluminum, alkylaluminum halide such as diethylaluminum chloride and diisobutylaluminum chloride, alkylaluminum hydride such as diethylaluminum hydride, alkylaluminum alkoxide such as diethylaluminum ethoxide, methyl Examples include alumoxanes such as alumoxane and tetrabutylalumoxane, and complex organoaluminum compounds such as dibutyl methylboronate and lithium aluminum tetraethyl. It is also possible to use a mixture of two or more of these.

  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 above-described catalyst. For example, organic silicon compounds such as diphenyldimethoxysilane and tert-butylmethyldimethoxysilane, esters such as ethyl acetate, butyl benzoate, methyl p-toluate, and dibutylphthalate, ketones such as acetone and methyl isobutyl ketone, diethyl ether And electron donating compounds such as ethers such as benzoic acid and propionic acid, and alcohols such as ethanol and butanol.

(Iii) Polymerization format and polymerization solvent Polymerization formats include 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, linear propylene polymer polymerization is performed by bulk polymerization, linear ethylene / propylene random copolymer polymerization is performed by gas phase polymerization, and linear propylene polymer polymerization is followed by bulk polymerization. Examples of the method include vapor phase polymerization, and linear ethylene / propylene random copolymer polymerization may be performed by gas phase polymerization.

(Iv) Polymerization additive Although the polymerization additive depends on the combination with the catalyst, the case where an aromatic ester such as butyl benzoate is added to the titanium trichloride catalyst consumes more hydrogen. preferable.

(V) Polymerization pressure In the semi-batch polymerization, it is possible to carry out the polymerization pressure at a constant value or to change it at any time during the production of the linear propylene polymer. When the polymerization pressure is set high, there is an advantage that the catalyst activity can be increased, but there is a disadvantage that the amount of unreacted propylene to be recovered increases. Therefore, the polymerization pressure is 0.2 to 5 MPa, preferably about 0.3 to 2 MPa. Is preferred.
In addition, it is possible to carry out the polymerization pressure at a constant value or to change it at any time during the production of the linear ethylene / propylene random copolymer, but it is preferable to carry out at about 0.1 to 0.2 MPa. .

(Vi) Polymerization temperature Although it does not specifically limit regarding polymerization temperature in this invention, 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.

(Vii) Polymerization time In this invention, although polymerization time is not specifically limited, It is normally implemented in 30 minutes-10 hours. In general, the production of linear propylene polymer is typically 2 to 5 hours for gas phase polymerization, 30 minutes to 2 hours for bulk polymerization, and 4 to 8 hours for slurry polymerization. The standard of the polymer 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.

(Viii) Production of linear propylene polymer portion In the sequential multi-stage polymerization step of at least two stages, hydrogen is supplied as propylene and a chain transfer agent in the previous polymerization stage, and propylene is present in the presence of the catalyst. Homopolymerization is performed to produce a linear propylene polymer portion.
At this time, the MFR of the linear propylene polymer portion in the linear propylene / ethylene block copolymer (component A-1) is not only to be 130 g / 10 min or more, but also to the first normal stress. In order to make the ratio to the shear stress 1.01 or more, hydrogen and propylene are supplied into the reactor in the previous polymerization step, and the hydrogen concentration relative to propylene is decreased with time in the presence of the catalyst. When propylene is polymerized while a linear propylene polymer is obtained, the gas concentration ratio (H ₂ / C ₃ ) between hydrogen and propylene in the unreacted gas should be kept below 0.1 molar ratio. Is preferred.

Examples of the method for controlling the gas concentration ratio (H ₂ / C ₃ ) of hydrogen and propylene in the unreacted gas at the end of the previous polymerization step include the following methods.
That is, as described above, in the semi-batch polymerization, it is possible to carry out the polymerization pressure at a constant value or to change it at any time during the production of the crystalline propylene polymer, so that the gas concentration of hydrogen and propylene in the unreacted gas As a method for reducing the ratio (H ₂ / C ₃ ), (i) a method in which the supply amount of propylene is kept constant and the supply amount of hydrogen is reduced, and (ii) a supply amount of propylene with a constant polymerization pressure. And (iii) a method for decreasing the supply amount of both propylene and hydrogen, and (iv) a method for increasing the supply amount of both propylene and hydrogen.
In the present invention, from the simplicity of control, (ii) a method of increasing the supply amount of propylene and decreasing the supply amount of hydrogen while keeping the polymerization pressure constant, that is, the ratio of hydrogen to propylene supplied to the reactor. A method in which (H ₂ / C ₃ ) is gradually decreased is preferable.
In batch polymerization, most of the required amount is charged before production, and the hydrogen consumption rate is adjusted, so that the gas concentration ratio of hydrogen to propylene (H ₂ / C ₃ ) in the unreacted gas is 0.1. It can control so that it may become below molar ratio.

  The consumption of hydrogen varies depending on the catalyst, the presence or absence of a polymerization additive, the polymerization time, etc., but in order to keep the hydrogen concentration at the end of production of the linear propylene polymer low, it is preferable that the consumption rate of hydrogen is larger. . From the viewpoint of the consumption rate of hydrogen, a Ziegler catalyst is generally preferable to a metallocene catalyst, and among Ziegler catalysts, a titanium trichloride type is more preferable than a so-called magnesium chloride-supported catalyst.

In this way, the amount of hydrogen is controlled, and at the end of the previous polymerization step (a), the gas concentration ratio (H ₂ / C ₃ ) of hydrogen and propylene in the unreacted gas is preferably 0.1 molar ratio or less. More preferably, the molar ratio is 0.09 or less, and further preferably 0.08 or less. Within this range, it is possible to suppress the introduction of hydrogen into the subsequent linear ethylene / propylene random copolymer production process, and it is easy to obtain a highly viscous copolymer.

  As for the supply timing of hydrogen necessary for the linear propylene polymer, it is preferable to charge most of the necessary amount before production. Further, during the semi-batch polymerization, the amount of hydrogen supplied to propylene can be gradually reduced. By doing so, the average residence time of hydrogen can be made longer than the average residence time in the reactor of propylene, hydrogen can be used more efficiently, and the supply amount can be reduced. As a result, the hydrogen concentration can finally be kept low. Further, hydrogen may be supplied at the end of propylene polymerization, or supply may be stopped. When the hydrogen supply is stopped, the supply may be stopped simultaneously with the end of the propylene polymerization, or the supply may be stopped in the middle of the polymerization.

(Ix) Production of linear ethylene / propylene random copolymer portion In the previous polymerization step (a), propylene was continuously supplied to produce a linear propylene polymer, and the reactor gas was purged once. Subsequently, in the subsequent polymerization step (b), a linear ethylene / propylene random copolymer portion is produced.
In the subsequent polymerization step (b), propylene, ethylene and hydrogen are continuously supplied, and propylene is present in the presence of the catalyst (the catalyst used in the previous polymerization step (a) (first step)). And ethylene are randomly copolymerized to produce a linear ethylene / propylene random copolymer portion, and a linear propylene / ethylene block copolymer is obtained as a final product.

  At this time, the ratio of the first normal stress difference and the shear stress in the melt viscoelasticity measurement of the linear propylene / ethylene block copolymer (component A-1) of the present invention needs to be 1.01 or more. Therefore, although depending on the type of process and catalyst, it is preferable to adjust the hydrogen of the chain transfer agent to a relatively low concentration.

  In the production of the linear ethylene / propylene random copolymer, hydrogen is not supplied in principle, but a small amount can be supplied for the purpose of finely adjusting the viscosity of the resulting propylene / ethylene random copolymer.

  Further, at the time of production of the linear ethylene / propylene random copolymer portion, it is preferable that the supply amount of propylene is decreased with time, while the supply amount of ethylene is supplied while being increased with time. By doing so, the intrinsic viscosity of the propylene / ethylene random copolymer portion can be increased, and the ratio between the first normal stress difference and the shear stress can be easily increased to 1.01 or more. This is because the chain transfer agent hydrogen is brought in somewhat from the polymerization step (a) to the polymerization step (b), but is consumed at the beginning of the polymerization step (b), and the ethylene concentration in the latter stage of polymerization where there is almost no hydrogen. It is considered that the increase in the intrinsic viscosity is possible because the polymerization reaction rate with respect to the chain transfer reaction rate is increased due to the increase.

  The linear propylene polymer portion is preferably a propylene homopolymer from the viewpoint of rigidity of the polypropylene resin composition of the present invention, but from the viewpoint of moldability, a copolymer of propylene and a small amount of a comonomer. It may be. Specific examples of the copolymer include α- other than propylene such as ethylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, and 4-methyl 1-pentene. A comonomer unit corresponding to one or more comonomers selected from the group consisting of olefin, styrene, vinylcyclopentene, vinylcyclohexane, vinylnorbornane and the like is preferably contained 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 linear propylene polymer portion, the linear ethylene / propylene random copolymer portion is polymerized. In order to adjust the die swell ratio and the molecular weight distribution value (Mw / Mn) to predetermined values, the linear ethylene / propylene random copolymer portion may be a high molecular weight linear ethylene / propylene random copolymer. preferable.
The polymerization of the linear ethylene / propylene random copolymer portion is preferably performed in a hydrogen atmosphere as low as possible or in a state substantially free of hydrogen in order to polymerize a high molecular weight polymer. The polymerization is carried out successively in the presence of the propylene polymer produced in the linear propylene polymer partial polymerization step and a catalyst. The polymerization temperature is usually selected from the range of 40 to 90 ° C., and the pressure is selected from the range of 2 × 10 ^{5 to} 35 × 10 ⁵ Pa.

(2) Physical property (A-1-i):
The MFR (230 ° C., 2.16 kg load) of the linear propylene polymer portion of component A-1 used in the present invention is 130 g / 10 min or more, preferably 200 to 3000 g / 10 min, more preferably 250 to 2000 g / 10 min. When the MFR is less than 130 g / 10 minutes, the surface appearance and the injection foam moldability of the polypropylene resin composition and the injection foam molded article are deteriorated.
The MFR is the MFR when the polymerization of the linear propylene polymer portion is completed, and when performing the multistage polymerization, the MFR is the MFR of the linear propylene polymer portion taken out from the final polymerization tank.

Characteristic (A-1-ii):
The composition ratio of the linear ethylene / propylene random copolymer portion of the component A-1 used in the present invention to the entire component A-1 is 2 to 50% by weight, preferably 5 to 40% by weight, More preferably, it is 7 to 20% by weight. That is, the ratio of the linear propylene polymer portion to the whole component A-1 is 50 to 98% by weight, preferably 60 to 95% by weight, more preferably 80 to 93% by weight. When the linear ethylene / propylene random copolymer portion is less than 2 wt% (that is, the linear propylene polymer portion exceeds 98 wt%), the polypropylene resin composition and the injection foam of the injection foam molded article Formability and impact strength are reduced. On the other hand, when the proportion of the linear ethylene / propylene random copolymer portion exceeds 50% by weight (that is, the linear propylene polymer portion is less than 50% by weight), the surface appearance and the injection foaming moldability deteriorate. To do.

Characteristic (A-1-iii):
The MFR (230 ° C., 2.16 kg load) of component A-1 used in the present invention needs to exceed 60 g / 10 minutes, preferably 70 g / 10 minutes or more, more preferably 100 g / 10 minutes or more, Preferably it is 100-500 g / 10min. When the MFR is 60 g / 10 min or less, the surface appearance and the injection foam moldability of the polypropylene resin composition and the injection foamed molded product are deteriorated. For example, the mold cavity clearance before foaming is about 1 to 2 mm. In molding having a portion, there may occur a case where short shot occurs and stable molding cannot be performed.

Characteristics (A-1-iv):
The die swell ratio of the whole component A-1 used in the present invention is 1.2 to 2.5, preferably 1.3 to 2.4, and more preferably 1.4 to 2.3. When the die swell ratio is less than 1.2, the polypropylene resin composition cannot maintain a good cell shape at a high magnification, and the injection foam moldability is lowered. On the other hand, those having a die swell ratio exceeding 2.5 are less practical because they are difficult to manufacture industrially.

Characteristics (A-1-v):
Component A-1 used in the present invention exhibits strain hardening in 180 ° C. extensional viscosity measurement. The effect of showing strain-hardening properties in this 180 ° C. extensional viscosity measurement is that, as described above, in the polypropylene resin composition of the present invention, foam breakage at the molten resin flow front end (flow front) during injection molding, etc. The resulting silver streak is unlikely to occur, the surface appearance is likely to be beautiful, and a foamed molded article having uniform fine bubbles at a high magnification is likely to be obtained.
The term “strain hardenability” as used herein means that the elongational viscosity gradually increases as the amount of stretch strain of the melt increases. It is a case of increasing.

  Here, as to the method for evaluating strain hardening, any method can be used in principle as long as the uniaxial elongation viscosity can be measured. For example, details of the measuring method and measuring instrument are known: Polymer 42 (2001) 8663 is described as a preferred measuring method, but as a measuring device, Rheometrics Ales (Jig: Extensive Visibility Fixture manufactured by TEA Instruments), Toyo Seiki Co., Ltd., Melten The method using Rheometer is mentioned.

  The degree of strain hardening is 2.0 or more, more preferably 2.5 or more, particularly preferably 3.0 or more, further preferably 5 in the 180 ° C. extensional viscosity measurement (strain rate: 1.0 / sec). It preferably has a strain hardening degree (λmax) of 0.0 or more. When the strain hardening degree (λmax) is less than 2.0, in the polypropylene resin composition and the injection-foamed molded article of the present invention, silver streak tends to occur during the injection-foaming molding, and the surface appearance tends to be lowered. In some cases, it is not possible to obtain an injection foam molded article having uniform fine bubbles.

Characteristic (A-1-vi):
Component A-1 used in the present invention has a first normal stress difference (N1) to shear stress (SS) ratio (N1 / SS) of 1.01 or more, preferably 1. 3 or more, more preferably 2.0 or more. If N1 / SS is less than 1.01, a good cell shape cannot be maintained, a high-magnification foamed molded article cannot be obtained, and surface tension tends to be reduced, resulting in a reduction in surface appearance. . On the other hand, there is no particular upper limit for N1 / SS, but if N1 / SS exceeds 5, the production becomes extremely difficult, so the practicality is small.

Other characteristics:
Component A-1 used in the present invention, the intrinsic viscosity _{[eta] copoly} of linear ethylene-propylene random copolymer portion is preferably 5.3~15dl / g, more preferably 6～14.5Dl / g, more preferably 6.5 to 14 dl / g.
When the intrinsic viscosity _{[eta] copoly} is less than 5.3 dl / g, there is a possibility that the injection foam molding is lowered. Further, the intrinsic viscosity _{[eta] copoly} is more than 15 dl / g, surface appearance and impact strength may be lowered.

  Component A-1 used in the present invention preferably has a ratio of a weight average molecular weight (Mw) and a number average molecular weight (Mn) representing a molecular weight distribution, and a molecular weight distribution value (hereinafter also referred to as Mw / Mn). It is 7-13, More preferably, it is 8-12. When the Mw / Mn is less than 7, the polypropylene resin composition cannot maintain a good cell shape, and a high-magnification foamed molded product tends to be not obtained. On the other hand, when Mw / Mn exceeds 13, production becomes extremely difficult.

  The ethylene content of the linear ethylene / propylene random copolymer portion of Component A-1 used in the present invention is preferably 15 to 80% by weight based on the total amount of the linear ethylene / propylene random copolymer. More preferably, it is 20-70 weight%, More preferably, it is 25-45 weight%. When the ethylene content is less than 15% by weight, the injection-foaming moldability and the surface appearance of the polypropylene resin composition and the injection-foamed molded product are liable to be deteriorated. On the other hand, when the ethylene content exceeds 80% by weight, the impact strength is reduced. There is a tendency to decrease.

  Furthermore, the weight average molecular weight (Mw) of the linear ethylene / propylene random copolymer portion of Component A-1 used in the present invention is preferably 1 million or more, more preferably 1.1 million to 8 million, and still more preferably. It is 1.2 million to 7 million, particularly preferably 1.5 to 4 million. When the weight average molecular weight (Mw) of the linear ethylene / propylene random copolymer portion is lower than 1,000,000, the effect of improving the injection foam moldability of the polypropylene resin composition tends to be insufficient.

MFR, die swell ratio, Mw, Mw / Mn, linear ethylene / propylene random copolymer part content and ethylene content are MFR meter, cross fractionator, Fourier transform infrared absorption spectrum analysis, gel permeation chromatography It is a value measured by (GPC). Intrinsic viscosity [η] _copy is obtained by using an Ubbelohde viscometer, strain hardening in 180 ° C. extension viscosity measurement, an extension viscometer, and N1 / SS measurement by using a dynamic viscoelasticity measuring device. To measure. The measurement conditions of main items are described in the examples.

(3) Blending ratio The blending ratio of the component A-1 in the entire component A used in the present invention is 30 to 100% by weight, preferably 40 to 100% by weight, more preferably 50 to 100% by weight of the component A. ~ 100% by weight. When the component A-1 is less than 30% by weight, the surface appearance and the injection foam moldability of the polypropylene resin composition of the present invention and the injection foam molded article thereof are lowered.

1-2. Other propylene polymers (component A-2)
Other propylene-based polymers (component A-2) used in the present invention are propylene homopolymers, copolymers of propylene and α-olefins such as propylene / ethylene random copolymers and propylene / ethylene block copolymers. Coalescence, and mixtures thereof. Of these, a copolymer of propylene and ethylene is preferable, and a propylene / ethylene block copolymer is particularly preferable.
Component A-2 has a feature that contributes to maintaining and improving physical properties such as surface appearance, injection foam moldability, impact strength, rigidity, and productivity in the polypropylene resin composition of the present invention.

(1) Production The production method of the other propylene polymer (component A-2) used in the present invention is not particularly limited, and is appropriately selected from known methods and conditions.
As the polymerization catalyst for propylene, a highly stereoregular catalyst is usually used, and examples thereof include a Ziegler catalyst and a metallocene catalyst.
In the presence of the catalyst, it is obtained by applying a production process such as a gas phase polymerization method, a liquid phase bulk polymerization method, or a slurry polymerization method.
Examples of the α-olefin in the propylene / α-olefin copolymer include α-olefins having 2 to 20 carbon atoms excluding propylene, and examples thereof include ethylene, butene-1, hexene-1, and octene-1. The α-olefin copolymerized with propylene may be used alone or in combination of two or more. Of these, ethylene and butene-1 are preferred.

(2) Physical properties The MFR (230 ° C., 2.16 kg load) of component A-2 used in the present invention is preferably 0.1 to 300 g / 10 minutes, more preferably 3 to 200 g / 10 minutes, and still more preferably. 10 to 100 g / 10 min, particularly preferably 20 to 60 g / 10 min. If the MFR is less than 0.1 g / 10 min, the surface appearance and injection foam moldability of the polypropylene resin composition and the injection foamed molded product tend to be lowered, and for example, the mold cavity clearance before foaming is 1 In molding having a thin portion of about 2 mm, short shot occurs and stable molding cannot be performed.

(3) Blending ratio The blending ratio of Component A-2 in the entire Component A used in the present invention is 0 to 70% by weight, preferably 0 to 60% by weight, particularly preferably 0, based on 100% by weight of Component A. ~ 50% by weight. When component A-2 exceeds 70% by weight, the surface appearance, injection foam moldability, physical properties and the like of the polypropylene resin composition of the present invention and the injection foam molded article thereof are deteriorated.

1-3. Blending ratio The blending ratio of the polypropylene resin (component A) in the polypropylene resin composition of the present invention is the polypropylene resin (component A), the propylene-ethylene block copolymer (component B) described later, and the postscript. In the total amount of 100% by weight with the ethylene-based elastomer (component C), the amount of component B and the amount of component C are excluded. In addition, the component A can also be used in mixture of 2 or more types as the component A.

2. Propylene-ethylene block copolymer (component B)
The propylene-ethylene block copolymer (component B) used in the present invention is a propylene-ethylene block copolymer having the following conditions (Bi) to (Bv), and the polypropylene resin of the present invention. The composition and its injection-foamed molded article have characteristics that contribute to the development of excellent surface appearance, impact strength, and injection-foaming moldability mainly including a low injection rate.
The propylene-ethylene block copolymer here is also referred to as propylene homopolymer or propylene-ethylene random copolymer (component BA) having an ethylene content of 7% by weight or less (hereinafter also referred to as component (BA)). And a propylene-ethylene random copolymer (component BB) (hereinafter also referred to as component (BB)) containing 3 to 20% by weight of ethylene more than the component (BA). It is a block copolymer in a general name obtained by sequential polymerization, and the component (BA) and the component (BB) do not necessarily have to be completely combined in a block shape.

Condition (Bi): 30 to 95% by weight of propylene alone or a propylene-ethylene random copolymer component (BA) having an ethylene content of 7% by weight or less in the first step using a metallocene catalyst. Propylene- obtained by sequentially polymerizing 70 to 5 wt% of a propylene-ethylene random copolymer component (BB) containing 3 to 20 wt% more ethylene than component (BA) in the process It must be an ethylene block copolymer.
Condition (B-ii): MFR (230 ° C., 2.16 kg load) is in the range of 0.5 to 100 g / 10 min.
Condition (B-iii): The melting peak temperature (Tm) measured by the DSC method is in the range of 110 to 150 ° C.
Condition (B-iv): The molecular weight distribution value (Mw / Mn) is in the range of 1.5-4.
Condition (Bv): In the temperature-loss tangent curve obtained by solid viscoelasticity measurement, the tan δ curve has a single peak at 0 ° C. or lower.

(1) Production (i) Metallocene Catalyst The production of the propylene-ethylene block copolymer (component B) used in the present invention requires the use of a metallocene catalyst.
The type of the metallocene catalyst is not particularly limited as long as the component B having the performance of the present invention can be produced. In order to satisfy the requirements of the present invention, for example, the following components (a ), (B) and, if necessary, a metallocene catalyst comprising component (c) is preferably used.
Component (a): at least one metallocene transition metal compound selected from transition metal compounds represented by the following general formula:
Component (b): at least one solid component selected from the following (b-1) to (b-4).
(B-1): A particulate carrier on which an organic aluminum oxy compound is supported.
(B-2): A particulate carrier carrying an ionic compound or Lewis acid capable of reacting with component (a) to convert component (a) into a cation.
(B-3): Solid acid fine particles.
(B-4): Ion exchange layered silicate.
Component (c): an organoaluminum compound.

As the component (a), at least one metallocene transition metal compound selected from transition metal compounds represented by the following general formula can be used.
^{_{Q (C 5 H 4 -aR 1}} ) (C 5 H 4 -bR 2) MeXY
[Wherein, Q represents a divalent linking group that bridges two conjugated five-membered ring ligands, Me represents a metal atom selected from titanium, zirconium, and hafnium, X and Y represent a hydrogen atom, Represents a halogen atom, a hydrocarbon group, an alkoxy group, an amino group, a nitrogen-containing hydrocarbon group, a phosphorus-containing hydrocarbon group or a silicon-containing hydrocarbon group, and X and Y may be independently, ie, the same or different. . R ¹ and R ² are hydrogen, hydrocarbon group, halogenated hydrocarbon group, silicon-containing hydrocarbon group, nitrogen-containing hydrocarbon group, oxygen-containing hydrocarbon group, boron-containing hydrocarbon group, or phosphorus-containing hydrocarbon group. Indicates. a and b are the number of substituents. ]

  Among them, preferred for the production of Component B have a substituted cyclopentadienyl group, a substituted indenyl group, a substituted fluorenyl group, and a substituted azulenyl group crosslinked with a silylene group, a germylene group or an alkylene group having a hydrocarbon substituent. Transition metal compounds comprising a ligand, and particularly preferably a silylene group having a hydrocarbon substituent, or a 2,4-position substituted indenyl group or 2,4-position substituted azenyl group bridged by a germylene group. And a transition metal compound composed of a ligand having the same.

As the component (b), at least one solid component selected from the aforementioned components (b-1) to (b-4) is used. Each of these components is a well-known thing, and can be used selecting it suitably from well-known techniques. Specific examples and manufacturing methods thereof are described in detail in JP-A No. 2002-284808, JP-A No. 2002-53609, JP-A No. 2002-69116, JP-A No. 2003-105015, and the like.
Of the component (b), particularly preferred is the ion-exchange layered silicate of component (b-4), and more preferred are chemical treatments such as acid treatment, alkali treatment, salt treatment, and organic matter treatment. Is an ion-exchange layered silicate.

Examples of organoaluminum compounds used as component (c) as needed are:
General formula: AlR _a P _3-a
(Wherein R represents a hydrocarbon group having 1 to 20 carbon atoms, P represents hydrogen, halogen or alkoxy group, a represents a number of 0 <a ≦ 3), trimethylaluminum, Trialkylaluminum such as tripropylaluminum and triisobutylaluminum or halogen- or alkoxy-containing alkylaluminum such as diethylaluminum monochloride and diethylaluminum monomethoxide. In addition, aluminoxanes such as methylaluminoxane can also be used. Of these, trialkylaluminum is particularly preferred.

  As a method for forming the catalyst, the component (a), the component (b) and, if necessary, the component (c) are brought into contact with each other to form a catalyst. In addition, the contact method is not specifically limited.

Moreover, the usage-amount of component (a), (b), and (c) is arbitrary. For example, the amount of component (a) used relative to component (b) is preferably in the range of 0.1 μmol to 1,000 μmol, particularly preferably 0.5 μmol to 500 μmol, relative to 1 g of component (b). The amount of component (c) used relative to component (b) is preferably such that the amount of transition metal is 0.001 to 100 μmol, particularly preferably 0.005 to 50 μmol, relative to 1 g of component (b).
Furthermore, it is preferable that the catalyst used in the present invention is subjected to a prepolymerization treatment in which a small amount of polymer is brought into contact with an olefin in advance.

(Ii) Sequential Polymerization In producing the propylene-ethylene block copolymer (component B) used in the present invention, it is necessary to sequentially polymerize the component (BA) and the component (BB).
That is, in the present invention, the component B is a block copolymer obtained by sequentially polymerizing components having different ethylene contents in the first step and the second step, in the polypropylene resin composition of the present invention and its injection foam molded product. Therefore, it is necessary for exhibiting excellent surface appearance, impact strength and injection foaming moldability even under a low injection rate.
Further, in the present invention, in order to prevent problems such as adhesion to the reactor, it is necessary to use a method of polymerizing the component (BB) after polymerizing the component (BA). is there.
When performing sequential polymerization, either a batch method or a continuous method can be used, but it is generally desirable to use a continuous method from the viewpoint of productivity.

In the case of a batch method, it is possible to polymerize component (BA) and component (BB) separately using a single reactor by changing the polymerization conditions with time. As long as the effects of the present invention are not impaired, a plurality of reactors may be connected in parallel.
In the case of a continuous process, since it is necessary to polymerize component (BA) and component (BB) separately, it is necessary to use a production facility in which two or more reactors are connected in series. As long as the effect is not inhibited, a plurality of reactors may be connected in series and / or in parallel for each of the component (BA) and the component (BB).

(Iii) Polymerization process As the polymerization process, an arbitrary polymerization method such as a slurry method, a bulk method, or a gas phase method can be used. Although it is possible to use supercritical conditions as intermediate conditions between the bulk method and the gas phase method, they are substantially equivalent to the gas phase method, and are therefore included in the gas phase method without particular distinction.
Since component (BB) is easily soluble in organic solvents such as hydrocarbons and liquefied propylene, it is desirable to use a vapor phase method in the production of component (BB).
For the production of the component (BA), there is no particular problem even if any process is used. Therefore, it is desirable to use a gas phase method.
Therefore, it is most desirable to first polymerize the component (BA) by the bulk method or the gas phase method using the continuous method, and then polymerize the component (BB) by the gas phase method.

(Iv) Other polymerization conditions The polymerization temperature can be used without any particular problem as long as it is within a commonly used temperature range. Specifically, a range of 0 ° C. to 200 ° C., more preferably 40 ° C. to 100 ° C. can be used.
Although the polymerization pressure varies depending on the process to be selected, it can be used without any problem as long as it is in a pressure range usually used. Specifically, a range of greater than 0 to 200 MPa, more preferably 0.1 MPa to 50 MPa can be used. At this time, an inert gas such as nitrogen may coexist.
When performing sequential polymerization of the component (BA) in the first step and the component (BB) in the second step, it is desirable to add a polymerization inhibitor into the system in the second step. In the case of producing a propylene-ethylene block copolymer, if a polymerization inhibitor is added to the reactor for carrying out the ethylene-propylene random copolymerization in the second step, the particle properties (fluidity, etc.) of the resulting powder, gel, etc. Product quality can be improved. Various technical studies have been made on this method, and examples thereof include Japanese Patent Publication Nos. 63-54296, 7-25960, and 2003-2939. It is desirable to apply the method to the present invention.

(2) Conditional condition (Bi):
The propylene-ethylene block copolymer (component B) used in the present invention is, as described above, using the metallocene catalyst, in the first step, propylene alone or ethylene content of 7% by weight or less, preferably 5% by weight or less. More preferably, 3% by weight or less of propylene-ethylene random copolymer component (BA) is 30 to 95% by weight, and in the second step, 3 to 20% by weight of ethylene is more than component (BA). Of propylene-ethylene random copolymer component (BB) containing preferably 6 to 18% by weight of ethylene, more preferably 8 to 16% by weight of ethylene. There is a need to. Here, when the difference in ethylene content between the second step component (BB) and the first step component (BA) is less than 3% by weight, the polypropylene resin composition of the present invention and the injection foam molding thereof are used. The impact strength and injection foamability of the body are reduced. On the other hand, when it exceeds 20 weight%, the compatibility of a component (BA) and a component (BB) will fall.
That is, it is possible to sequentially polymerize components having different ethylene contents in the first step and the second step, and in the polypropylene resin composition of the present invention and the injection foamed molded article thereof, excellent surface appearance including a low injection rate, In order to develop impact strength and injection foaming moldability, and to prevent problems such as adhesion to the reactor, the component (B-A) is polymerized and then the component (B- It is necessary to use the method of polymerizing B).

Condition (B-ii):
The MFR (230 ° C., 2.16 kg load) of the propylene-ethylene block copolymer (component B) used in the present invention is 0.5 to 100 g / 10 minutes, preferably 1 to 50 g / 10 minutes, more preferably It needs to be in the range of 2 to 35 g / 10 min. When the MFR is less than 0.5 g / 10 min, the surface appearance and injection foam moldability of the polypropylene resin composition and the injection foam molded article thereof are lowered. On the other hand, when it exceeds 100 g / 10 minutes, the impact strength decreases.

Condition (B-iii):
The melting peak temperature (Tm) measured by the DSC (Differential Scanning Calorimetry) method of the propylene-ethylene block copolymer (component B) used in the present invention is 110 to 150 ° C, preferably 115 to 148 ° C. Preferably it needs to exist in the range of 120-145 degreeC. When the Tm is less than 110 ° C., the surface appearance and the injection foam moldability of the polypropylene resin composition and the injection foam molded article thereof are deteriorated. On the other hand, when it exceeds 150 degreeC, the impact strength of a polypropylene resin composition and its injection foaming molding will fall.

Condition (B-iv):
The molecular weight distribution value (Mw / Mn) measured by the GPC method of the propylene-ethylene block copolymer (component B) used in the present invention is 1.5 to 4, preferably 1.8 to 3.8. Preferably it needs to be in the range of 2 to 3.5. When Mw / Mn is less than 1.5, it is difficult to produce industrially. On the other hand, when it exceeds 4, the surface characteristics of the polypropylene resin composition and the injection-foamed molded product thereof are deteriorated (a sticky feeling is likely to occur).

Condition (Bv):
The propylene-ethylene block copolymer (component B) used in the present invention has a tan δ curve having a single peak at 0 ° C. or lower in a temperature-loss tangent curve obtained by solid viscoelasticity measurement (DMA). is necessary.
That is, in the present invention, the polypropylene resin composition and the injection foam molded product thereof, such as the surface appearance including the low injection rate, the impact strength, the injection foam moldability, etc. are expressed well. In the block copolymer (component B), it is necessary that the component (BA) and the component (BB) are not phase-separated, but in that case, the tan δ curve is single at 0 ° C. or lower. The peak is shown.
In this case, the two components are mixed in molecular order and have a single peak at a temperature intermediate between the glass transition temperatures of both components. That is, whether the phase separation structure is taken or not can be determined in the temperature-tan δ curve in the solid viscoelasticity measurement. In order to maintain compatibility (surface appearance and impact strength), the tan δ curve is It is necessary to have a single peak below 0 ° C.
Incidentally, when the component (BA) and the component (BB) are in a phase separation structure, the glass transition temperature of the amorphous part contained in the component (BA) and the component (BB) Since the glass transition temperatures of the included amorphous parts are different, there are a plurality of peaks.
Specifically, solid viscoelasticity measurement is performed by applying a sinusoidal strain of a specific frequency to a strip-shaped sample piece and detecting the generated stress. Here, the frequency is 1 Hz, and the measurement temperature is raised stepwise from −60 ° C. until the sample is melted and cannot be measured. Further, it is recommended that the magnitude of distortion is about 0.1 to 0.5%. From the obtained stress, the storage elastic modulus G ′ and the loss elastic modulus G ″ are obtained by a known method, and the loss tangent (= loss elastic modulus / storage elastic modulus) defined by this ratio is plotted against the temperature. It shows a sharp peak in the temperature range of 0 ° C. or lower, and generally the peak of the tan δ curve at 0 ° C. or lower is for observing the glass transition of the amorphous part, and here this peak temperature is the glass transition temperature Tg (° C.). Define as

(3) Blending Ratio The blending ratio of the propylene-ethylene block copolymer (component B) in the polypropylene resin composition of the present invention is 1 for the total amount of component A, component B and component C of 100% by weight. -40% by weight, preferably 2-38% by weight, particularly preferably 3-35% by weight.
When the component B is less than 1% by weight, the surface appearance, impact strength, and injection foam moldability of the polypropylene resin composition of the present invention and the injection foam molded article thereof are lowered. On the other hand, when it exceeds 40% by weight, rigidity, heat resistance and the like are lowered. In addition, this component B can also be used in mixture of 2 or more types.

3. Ethylene-based elastomer (component C)
The ethylene-based elastomer (component C) used in the present invention is an ethylene / α-olefin copolymer elastomer or the like. It has the characteristic which contributes to expressing stability etc.

(1) Kinds As component C, for example, ethylene / propylene copolymer elastomer (ethylene propylene rubber; EPR), ethylene / butene copolymer elastomer (EBR), ethylene / hexene copolymer elastomer (EHR), ethylene Examples include ethylene / α-olefin copolymer elastomers such as octene copolymer elastomer (EOR); ethylene / α-olefin / diene terpolymer elastomers such as ethylene / propylene / diene copolymer. Two or more of these elastomers can be mixed and used.

(2) Production Component C is produced by polymerizing each monomer in the presence of a catalyst.
Examples of the catalyst include titanium compounds such as titanium halides, 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. A metallocene compound catalyst or the like can be used. As the polymerization method, polymerization can be performed by applying a production process such as a gas phase fluidized bed, a solution method, or a slurry method.

(3) Physical properties The MFR (190 ° C., 2.16 kg load) of Component C is preferably 0.5 g / 10 min or more, more preferably 1 g / 10 min or more, and particularly preferably 5 g / 10 min or more.
Considering the automobile member which is the main application of the present invention, those having an MFR in the above range are preferable because a polypropylene resin composition and an injection foam molded article having good surface appearance and impact strength can be obtained in many cases.

(4) Blending ratio The blending ratio of the ethylene elastomer (component C) in the polypropylene resin composition of the present invention is 1 to 40% by weight with respect to 100% by weight of the total amount of component A, component B and component C. , Preferably 3 to 35% by weight, particularly preferably 5 to 25% by weight.
When the component C is less than 1% by weight, the impact strength and dimensional stability of the polypropylene resin composition of the present invention and the injection-foamed molded article thereof are lowered. On the other hand, when it exceeds 40% by weight, the surface appearance, injection foam moldability, heat resistance and the like are lowered.

4). Foaming agent (component D)
The foaming agent (component D) used in the present invention is a chemical foaming agent, a physical foaming agent, a microcapsule, or the like, and in a polypropylene resin composition, good injection foaming moldability (surface tension, foaming ratio, cell form). It has the feature which contributes to expressing.

(1) Kind, function, etc. Examples of the type of component D include chemical foaming agents, physical foaming agents, and microcapsules. Any material that can be normally used for injection foam molding can be used without particular limitation. These foaming agents can be used alone or in admixture of two or more.
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), and 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 Such organic acid metal salts can be used and added together, and nucleating agents such as inorganic fine particles such as talc and lithium carbonate can also be added.

  As the chemical foaming agent, an inorganic type is preferable from the viewpoint that a normal injection molding machine can be used safely and uniform fine bubbles are easily obtained in the molded body. As described above, various chemical foaming agents include inorganic and organic types. Preferred examples include sodium bicarbonate, citric acid, sodium citrate, and mixtures of two or more thereof. Preferred are sodium bicarbonate, a combination of sodium bicarbonate and sodium citrate, and a combination of sodium bicarbonate and citric acid.

These chemical foaming agents are processed, for example, into particles having an average particle diameter of 1 to 100 μm, mixed with the components A to C kneaded and sprinkled on the granulated product at the time of injection foam molding, and then injection molding machine In the case of being supplied to an injection molding machine or injection molding, it is injected from the middle of a cylinder of an injection molding machine and decomposes in the cylinder to generate a gas such as carbon dioxide.
In addition, the chemical foaming agent is granulated as a masterbatch based on a polyolefin resin from the viewpoints of handleability, storage stability, kneading of the components A to C, dispersibility in the granulated product, and the like. Can also be used. 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 is decomposed in the cylinder of the injection molding machine, and the foaming residue can be a 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, air, 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 inert solvent vapor include dichloromethane, chloroform, carbon tetrachloride, chlorofluorocarbon, and nitrogen trifluoride. Among these, it is preferable to use an inert gas because it is not necessary to use steam, is inexpensive, and has a very low risk of environmental pollution and fire. Among them, carbon dioxide, nitrogen, argon, and helium are preferable. In particular, carbon dioxide and nitrogen are preferable.
Furthermore, the physical foaming agent is preferably in a supercritical state, which has the advantage of facilitating gas melting into the resin.
A physical foaming agent is injected as a gaseous or supercritical fluid into a kneaded or granulated product of the above components A to C in a cylinder of an injection molding machine, and dispersed or dissolved, and injected into a mold. After that, the pressure is released to function as a foaming 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 supplied to an injection molding machine or the like after being kneaded with the components A to C, mixed in advance with a granulated product, or the like.

  These component D is preferably used in combination with a chemical foaming agent and a physical foaming agent in order to obtain more uniform and fine bubbles in the polypropylene resin composition and the injection foamed molded article, and to increase the expansion ratio. In particular, it is preferable to use an inorganic chemical foaming agent in combination with carbon dioxide or nitrogen as a physical foaming agent.

(2) Blending ratio The blending ratio of the foaming agent (component D) in the polypropylene resin composition of the present invention may be appropriately set in view of the type of foaming agent, the foaming ratio, injection foaming molding conditions, and the like. For example, when a chemical foaming agent is used, 0.001 to 10 parts by weight is preferable with respect to 100 parts by weight of the total amount of Component A, Component B and Component C, more preferably 0.01 to 8 parts by weight, Preferably it is 0.1-6 weight part.
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 Component D is less than 0.001 part by weight, the polypropylene resin composition does not sufficiently foam, whereas when the blending ratio exceeds 10 parts by weight, the polypropylene resin composition and the injection foamed molded article The mechanical strength such as the impact strength of the foam is reduced, or secondary foaming phenomenon (the phenomenon that the surface of the injection-foamed molded body swells in a blistering shape due to excessive residual foaming gas) occurs, which is also disadvantageous economically. .

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 polypropylene resin composition does not sufficiently foam or the mechanical strength of the injection-foamed molded article decreases. To do.
In addition, the component D can also use 2 or more types together.

5. Filler (component E)
In the present invention, the filler (component E) used as necessary is an inorganic or organic filler. Component E contributes to the development of properties such as injection-foam moldability, rigidity, physical properties such as polypropylene resin compositions and injection-foamed molded articles, dimensional stability (reduction of linear expansion coefficient), and environmental adaptability. Has features.

(1) Kind, shape, etc. Specific examples of component E include, for example, as inorganic fillers, oxides such as silica, diatomaceous earth, barium ferrite, beryllium oxide, pumice, and pumice balun, aluminum hydroxide, magnesium hydroxide, Hydroxides such as basic magnesium carbonate, carbonates such as calcium carbonate, magnesium carbonate, dolomite, and dawsonite, sulfates or sulfites such as calcium sulfate, barium sulfate, ammonium sulfate, and calcium sulfite, talc, clay, mica, glass fiber , Glass balloons, glass beads, calcium silicate, wollastonite, montmorillonite, bentonite and other silicates, carbon black, graphite, carbon fiber, carbon hollow sphere and other carbons, molybdenum sulfide, boron fiber, zinc borate , Barium metaborate , Calcium borate, sodium borate, magnesium oxysulfate, 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 the component E, Any shape, such as a granular form, plate shape, rod shape, fiber shape, and a whisker shape, can be used.
Of these, plate-like, fiber-like, and whisker-like ones are preferred in that the polypropylene resin composition and the injection-foamed molded article of the present invention having excellent balance of dimensional stability and physical properties can be easily obtained. 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 components E, at least one selected from talc, polyester fiber, whisker, glass fiber, and carbon fiber, particularly talc and polyester fiber, has physical properties such as injection foamability, dimensional stability, and rigidity, and economic efficiency. From the viewpoint of easily obtaining a polypropylene-based resin composition and an injection-foamed molded article having an excellent balance. 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 referred to here is an ultrafine fiber (generally 2 μmφ or less, especially 1 μmφ or less) such as basic magnesium sulfate fiber, potassium titanate fiber, aluminum borate fiber, calcium silicate fiber, calcium carbonate fiber, or ultrafine carbon fiber. It is a shape.

Among them, talc having an average particle size of 15 μm or less, preferably 0.5 to 10 μm, particularly preferably 2 to 8 μm, is particularly excellent in balance between physical properties such as injection foam moldability, dimensional stability, rigidity, and economic efficiency. A polypropylene resin composition and an injection-foamed molded article are preferred because they are easily obtained.
The 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.

  For these components E, organic titanate coupling agents, organic silane coupling agents, unsaturated carboxylic acids, or those which have been surface-treated with a modified polyolefin grafted with an anhydride thereof, fatty acids, fatty acid metal salts, fatty acid esters, etc. are used. Alternatively, two or more types may be used in combination for surface treatment.

(2) Manufacturing The manufacturing method of these components E is not specifically limited, It manufactures with a well-known various manufacturing method. For example, in the case of talc, a product obtained by mechanically pulverizing a naturally produced product can be obtained by classifying the talc more precisely once or a plurality of times. 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, cyclone air separator, micro separator, cyclone air separator, sharp cut separator, etc. to adjust to the average particle size shown in the present invention. Or dry classification. After pulverization to a specific particle size, classification is preferably performed with a sharp cut separator.

(3) Blending ratio In the present invention, the blending ratio of Component E used as necessary is preferably 1 to 60 parts by weight with respect to 100 parts by weight of the total amount of Component A, Component B and Component C. Preferably it is 1.5-50 weight part, Most preferably, it is 2-35 weight part. When the blending ratio of Component E is less than 1 part by weight, the rigidity and dimensional stability of the polypropylene resin composition and the injection foamed molded product tend to be lowered. On the other hand, when it exceeds 60 parts by weight, the injection foaming moldability, impact strength and surface appearance tend to be lowered.
In addition, you may use 2 or more types of component E together.

6). Elastomers other than ethylene elastomer (component C) (component F)
In the present invention, the elastomer (component F) other than the ethylene elastomer (component C) used as necessary is an elastomer such as a styrene elastomer. Component F has a feature that contributes to manifesting further improvements in impact strength, surface appearance, and the like of the polypropylene resin composition and injection-foamed molded article of the present invention.

(1) Kinds Examples of component F include styrene-ethylene / butylene copolymer (SEB), styrene-ethylene / propylene copolymer (SEP), styrene-ethylene / butylene-styrene copolymer (SEBS), and ethylene. -Ethylene / Butylene-Ethylene Copolymer (CEBC), Styrene-Ethylene / Butylene-Ethylene Copolymer (SEBC), Hydrogenated Styrene / Butadiene Elastomer (HSBR), Styrene / Isoprene / Styrene Triblock (SIS), Styrene -Ethylene-propylene-styrene copolymer (SEPS), styrene-ethylene-ethylene-propylene-styrene copolymer (SEEPS), styrene-butadiene-butylene-styrene copolymer (SBBS), partially hydrogenated styrene-isoprene- Styrene copolymer, part Examples thereof include styrene-based elastomers such as a fractionated hydrogenated styrene-isoprene / butadiene-styrene copolymer.
Two or more of these elastomers can be mixed and used.

(2) Production In the case of styrene elastomer, for example, component F can be produced by a normal anionic polymerization method and a polymer hydrogenation technique thereof.

(3) Physical properties The MFR (190 ° C., 2.16 kg load) of component F is preferably 0.5 g / 10 minutes or more, more preferably 1 g / 10 minutes or more, and particularly preferably 2 g / 10 minutes or more.
Considering the automobile member which is the main application of the present invention, those having an MFR in the above range are preferable because a polypropylene resin composition and an injection foam molded article having good surface appearance and impact strength can be obtained in many cases.

(4) Blending ratio The blending ratio of the elastomer (component F) other than the ethylene elastomer (component C) in the polypropylene resin composition of the present invention is 100 parts by weight of the total amount of component A, component B and component C. The amount is preferably 1 to 40 parts by weight, more preferably 1.5 to 30 parts by weight, and particularly preferably 2 to 20 parts by weight.
When the component F is less than 1 part by weight, the impact strength and dimensional stability of the polypropylene resin composition of the present invention and the injection-foamed molded product tend to be lowered. On the other hand, when it exceeds 40 parts by weight, the surface appearance and heat resistance tend to be lowered.

7). Optional addition component (component G)
In the polypropylene resin composition of the present invention, in addition to the components A to F, if necessary, the effects of the present invention can be further improved, for example, the effects of the invention can be further improved or other effects can be imparted. Therefore, an optional additive component (component G) 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, antiionics such as nonionics, Dispersants such as organic metal salts, lubricants such as fatty acid amides, metal deactivators such as nitrogen compounds, nonionic surfactants, polyolefins such as polypropylene other than the components A to F, polyamides, Examples thereof include thermoplastic resins such as polyester, fillers, and the like. Two or more of these components may be used in combination, may be added to the composition, may be added to each component, or two or more of these components may be used in combination.

As light stabilizers and ultraviolet absorbers, for example, hindered amine compounds, benzotriazoles, benzophenones and salicylates are effective for imparting and improving the weather resistance and durability of polypropylene resin compositions and injection-foamed molded articles. .
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.

Moreover, as a nucleating agent, for example, inorganic, sorbitol, carboxylic acid metal salt, and organic phosphate, the rigidity, heat resistance and hardness of polypropylene resin composition and injection foam molding, injection foam molding It is effective for imparting and improving properties.
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, inorganic or organic pigments, impart and improve the appearance, appearance, texture, commercial value, weather resistance, durability, etc. of polypropylene resin compositions and injection-foamed molded articles. This is effective.
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.

As antioxidants, for example, phenolic, phosphorous and sulfur antioxidants, impart and improve heat resistance stability, processing stability, heat aging resistance, etc. of polypropylene resin compositions and injection foam molded products. This is effective.
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.

As the antistatic agent, for example, an antistatic agent such as a nonionic or cationic one is effective for imparting and improving the antistatic property of the polypropylene resin composition and the injection-foamed molded article.
Specific examples include polyoxyethylene alkylamines; polyoxyethylene alkylamides; polyoxyethylene alkylphenyl ethers; stearic acid monoglycerides; alkyldiethanolamines; alkyldiethanolamides; alkyldiethanolamine fatty acid monoesters;

[II] Method for Producing Polypropylene Resin Composition, Method for Producing Injection Foam Molded Article, and Uses As a method for producing the polypropylene resin composition of the present invention, Component A to Component D, and optionally, Component E, Method of blending component F and component G in the above blending ratio, dry blending such as dusting or hand blending, method of mixing using various blenders such as V blender and tumbler mixer, mixer, etc., single screw extruder , A method of kneading and granulating using a conventional kneader such as a twin screw extruder, Banbury mixer, roll mixer, Brabender plastograph, kneader, and each of the above components separately (or partially blended) ) A method of directly supplying to an injection molding machine can be mentioned.

When selecting a kneading / granulating method, it is usually preferable to knead / granulate using a twin screw extruder. In this kneading and granulation, the blends of the components A to G may be kneaded at the same time, and each component is divided in order to improve performance, for example, first, a part of the components A and C Alternatively, the whole can be kneaded, and then the remaining components can be kneaded and granulated. In addition, when all or part of component D is mixed and kneaded in the injection foam molding stage, kneading and granulating are performed only with components excluding all or part of component D.

The injection foam molding method for producing the injection foam molding in the present invention is not particularly limited, and usually includes a foam molding method using an injection molding machine, an injection compression molding machine, or the like.
Examples of the drive system such as the injection molding machine and the injection compression molding machine to be used include the hydraulic type, the electric type, and the combination of both as described above, and any type of molding machine can be used.
Incidentally, the injection rate (injection speed) in these molding machines generally tends to be higher when the injection mechanism is an electric type.
As an injection foam molding method, for example, a polypropylene resin composition containing at least part of component D is injected and filled in a mold cavity while reversing the movable mold at a pressure equal to or higher than the foaming pressure. There is a method in which the core layer is foamed by further retracting the movable mold after the filling is completed.

  Also, for example, a polypropylene resin composition composed of components excluding all or part of component D is supplied to an injection molding machine, and component D such as the physical foaming agent is also compressed or supercritical. In addition to the direct molding machine, there is a method of injecting into a mold and molding an injection foam molded article. That is, a polypropylene resin composition containing a chemical foaming agent is supplied to an injection molding machine, and at the same time, a physical foaming agent is directly controlled and introduced into the molding machine for molding. This method can also be used in a molding method in which the skin layer is formed by injection filling while retracting the movable mold, and then the core layer is foamed by retracting the movable mold.

Further, for example, the mold is composed of a fixed mold and a movable mold capable of moving forward and backward, and an initial mold cavity clearance (T0) smaller than the mold cavity clearance (T1) corresponding to the shape position of the final product. ) Having a molten or semi-molten polypropylene resin composition injected and filled in the mold cavity, and retracting the movable mold to the mold cavity clearance (T1) (core back), and using a foaming agent There is a mold opening injection foaming method including a foaming step of filling a cavity of a mold cavity with an expansion pressure.
This molding method is preferable because the surface appearance and injection foam moldability of the polypropylene resin composition and the injection foam molded article can be expressed at a high level. Among these, in the molding method, it is preferable that the injection rate in the injection step of injecting and filling the polypropylene resin composition with respect to 100% of the pre-foamed molded body filling volume is 20% / second or more, and 50% / second. The above is more preferable. The molding method under these conditions can exhibit the above-described injection foam moldability and surface appearance at a higher level.

  Moreover, the injection foamed molded article in the present invention has an average cell diameter of preferably 500 μm or less, more preferably 200 μm or less, and a thickness formed on the surface of at least one side of the foam layer, preferably 10 μm or more and 1000 μm or less. More preferably, it has a non-foamed layer of 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, when the thickness of the non-foamed layer is less than 10 μm, the surface is not beautiful and the rigidity tends to decrease, and when it exceeds 1000 μm, it is difficult to obtain light weight.

  Further, the expansion ratio of the injection foamed molded product in the present invention is preferably 2.0 times or more and 10.0 times or less, more preferably 2.5 times or more and 6.0 times or less, and more preferably 3.0 times or more and 6.0 times. The following are particularly preferred: If the expansion ratio is less than 2.0 times, the lightness tends to be difficult to obtain, whereas if the expansion ratio exceeds 10.0 times, the rigidity tends to decrease significantly. The expansion ratio is the ratio of the specific gravity of the foamed molded product to the non-foamed molded product that was injection-molded under the same conditions except that no foaming agent was added to the 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 thickness.

  Applications of the polypropylene resin composition and injection-foamed molded article of the present invention include automobile parts, household appliances such as television, industrial parts including electronic parts, etc., building material parts, preferably automobile parts, especially trims, ceilings. Automotive interior parts such as materials, trunks, instrument panels, pillars.

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 (a) Silver streak:
The degree of occurrence of silver streaks in the foamed molded product was evaluated in the following three stages, compared with a separately produced non-foamed molded product.
Same level as non-foamed molded products ...
There are some silver streaks on the surface of the molded body.
The molded product has a lot of silver streaks over the entire surface ...
In this case, ◯ and Δ are levels that are judged to have practicality.

(2) Injection foam moldability (a) Surface tension:
The degree of surface tension of the foamed molded product was evaluated in the following three stages as compared with a separately produced non-foamed molded product.
Exactly the same level as a non-foamed molded product, or with very slight irregularities on the surface of the molded body.
Those with irregularities on the surface of the molded body
The molded product has many irregularities on the entire surface .... ×
In this case, ◯ and Δ are levels that are judged to have practicality.

(B) Foaming ratio:
It calculated | required by the plate | board thickness / initial stage thickness of the foaming molding. The thickness of the molded body obtained under the condition of cavity clearance after core back / initial cavity clearance = 2.7 times the core back amount was evaluated. The evaluation criteria are the following three stages.
However, the initial cavity clearance = 1.3 mm. Therefore, the cavity clearance after the core back is 3.5 mm.
The thickness of the entire molded body is exactly the same as the cavity clearance after the core back.
There are some places where the thickness of the molded body is partially thinner than the cavity clearance after the core back.
The overall thickness of the molded product is thinner than the cavity clearance after the core back.
In this case, ◯ and Δ are levels that are judged to have practicality.

(C) Cell form:
A micrograph of a cross section obtained by cutting the foam molded body in the thickness direction was visually observed and evaluated. The evaluation criteria are the following three stages.
The cell diameter is fine and uniform throughout.
Cell diameter is small and partly non-uniform.
Cell diameter is non-uniform throughout or completely peeled
In this case, ◯ and Δ are levels that are judged to have practicality.

(3) Charpy impact strength (notched)
Measured at a measurement ambient temperature of 23 ° C. in accordance with JIS K7111. However, the composition of this test piece is obtained by removing the foaming agent (component D) from each formulation shown in Table 3. The test piece is 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.
The tendency (large or small) of the impact strength of the blend excluding the foaming agent (component D) is considered to be very close to the impact strength of the blend of all components (component A to component F) shown in Table 3. Is done. In particular, in the industrial parts field including automobile parts and the like, it is determined that a Charpy impact strength value of 5 KJ / m ² or more has practicality.

(4) MFR
Conforms to JIS K7210. Test temperature: 230 ° C., load: 2.16 kg. However, component C is 190 ° C., load: 2.16 kg.

(5) Content of linear ethylene / propylene random copolymer portion and ethylene content (a) Analytical apparatus used:
(A-1) Cross sorter:
Diamond Instruments CFC T-100 (hereinafter abbreviated as CFC)
(A-2) Fourier transform infrared absorption spectrum analysis:
FT-IR, Perkin Elmer 1760X
The fixed wavelength infrared spectrophotometer attached as a CFC detector is removed, and an FT-IR is connected instead, and this FT-IR is used as a detector. The transfer line from the outlet of the solution eluted from the CFC to the FT-IR is 1 m long, and the temperature is maintained at 140 ° C. throughout the measurement. The flow cell attached to the FT-IR has an optical path length of 1 mm and an optical path width of 5 mmφ, and the temperature is maintained at 140 ° C. throughout the measurement.
(A-3) Gel permeation chromatography (GPC):
The GPC column in the latter part of the CFC is used by connecting three AD806MS manufactured by Showa Denko KK in series.

(B) CFC measurement conditions:
(B-1) Solvent: Orthodichlorobenzene (hereinafter also referred to as ODCB)
(B-2) Sample concentration: 4 mg / mL
(B-3) Injection amount: 0.4 mL
(B-4) Crystallization: The temperature is lowered from 140 ° C. to 40 ° C. over about 40 minutes.
(B-5) Sorting method:
The fractionation temperature at the time of temperature-raising elution fractionation is 40, 100, and 140 ° C., and fractionation is performed in 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 are defined. W ₄₀ + W ₁₀₀ + W ₁₄₀ = 100. Moreover, each fractionated fraction is automatically transported to the FT-IR analyzer as it is.
(B-6) Solvent flow rate during elution: 1 mL / min

(C) FT-IR measurement conditions:
After elution of the sample solution starts from GPC at the latter stage of CFC, FT-IR measurement is performed under the following conditions, and GPC-IR data is collected for each of the above-described fractions 1 to 3.
(C-1) Detector: MCT
(C-2) Resolution: 8 cm ⁻¹
(C-3) Measurement interval: 0.2 minutes (12 seconds)
(C-4) Number of integrations per measurement: 15 times

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

A calibration curve is created by injecting 0.4 mL of a solution dissolved in ODCB (containing 0.5 mg / mL BHT) so that each is 0.5 mg / mL. The calibration curve uses a cubic equation obtained by approximation by the least square method. Conversion to molecular weight uses a general-purpose calibration curve with reference to “Size Exclusion Chromatography” written by Sadao Mori (Kyoritsu Shuppan). The following numerical values are used for the viscosity equation ([η] = K × M ^α ) used at that time.
(D-1) When creating a calibration curve using standard polystyrene:
K = 0.000138, α = 0.70
(D-2) During sample measurement of component A-1:
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. Ask.

(E) Content of linear ethylene / propylene random copolymer portion:
The content (Wc) of the ethylene / propylene random copolymer portion in Component A-1 used in the present invention is theoretically defined by the following formula (I), and is determined 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. The measured average ethylene content (unit: wt%), and B ₄₀ and B ₁₀₀ are the ethylene content (unit: wt%) of the linear ethylene / propylene random copolymer portion 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 the formula (I) is a term for calculating the amount of the linear ethylene / propylene random copolymer portion contained in the fraction 1 (portion soluble at 40 ° C.). When fraction 1 contains only a linear ethylene / propylene random copolymer and no linear propylene polymer, W ₄₀ is the linear ethylene / propylene random derived from fraction 1 as it is Fraction 1 contributes to the copolymer content, but in addition to the component derived from the linear ethylene / propylene random copolymer, a small amount of the component derived from the linear propylene polymer (component with extremely low molecular weight) And atactic polypropylene), it is necessary to correct the portion. Therefore, by multiplying W ₄₀ by A ₄₀ / B ₄₀ , the amount derived from the linear ethylene / propylene random copolymer portion 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 linear ethylene / propylene random copolymer contained in fraction 1 is 40% by weight In the fraction 1, 30/40 = 3/4 (ie, 75% by weight) is derived from a linear ethylene / propylene random copolymer, and 1/4 is derived from a linear propylene polymer. Thus, the operation of multiplying A ₄₀ / B ₄₀ by the first term on the right side means that the contribution of the linear ethylene / propylene random copolymer is calculated from the weight% of fraction 1 (W ₄₀ ). The same applies to the second term on the right side. For each fraction, the linear ethylene / propylene random copolymer partial content is calculated by adding the contribution of the linear ethylene / propylene random copolymer. .

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

(E-2) The ethylene content corresponding to the peak position in the differential molecular weight distribution curve of fraction 1 is 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 linear ethylene / propylene random copolymer portion contained in each fraction, but it is practically impossible to obtain this value analytically. This is because there is no means for completely separating and fractionating the linear propylene polymer and the linear ethylene / propylene random copolymer 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. Further, B ₁₀₀ has crystallinity derived from an ethylene chain, and the amount of the linear ethylene / propylene random copolymer contained in these fractions includes the linear ethylene / propylene random copolymer contained in the fraction 1. Due to the two reasons that it is relatively small compared to the amount of polymer, the approximation to 100 is closer to the actual situation and causes almost no error in calculation. Therefore, the analysis is performed with B ₁₀₀ = 100.

(E-3) For the above reason, the content (Wc) of the linear ethylene / propylene random copolymer portion is determined according to the following formula.
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 (wt%) of the linear ethylene / propylene random copolymer having no crystallinity, and the second term W ₁₀₀ × A _100/100 is a linear ethylene / propylene random copolymer partial content (% by weight) having crystallinity.
_Here, the average ethylene content _A 40 of _{B 40} and each of the fractions obtained by the CFC measurement 1 and _{2, A 100} is determined as follows.
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 is 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, a polymer having no crystallinity at 40 ° C. (for example, most of the linear ethylene / propylene random copolymer or extremely low molecular weight in the linear propylene polymer portion) It has the meaning that it is a temperature condition necessary and sufficient for fractionating only the component and the atactic component). 100 ° C. is a component that is insoluble at 40 ° C. but becomes soluble at 100 ° C. (for example, in a linear ethylene / propylene random copolymer, it has crystallinity due to the chain of ethylene and / or propylene) The temperature is necessary and sufficient to elute only the components and the linear propylene polymer having low crystallinity. 140 ° C. means a component that is insoluble at 100 ° C. but becomes soluble at 140 ° C. (for example, a component having particularly high crystallinity in a linear propylene polymer and a linear ethylene / propylene random copolymer) The temperature is necessary and sufficient to elute only the component having extremely high molecular weight and extremely high ethylene crystallinity and recover the entire amount of propylene / ethylene block copolymer used for analysis. W ₁₄₀ does not contain a linear ethylene / propylene random copolymer portion at all, or even if it is present, it is very small amount and can be substantially ignored. This is excluded from the calculation of the polymer content and the ethylene content of the linear ethylene / propylene random copolymer.

(F) Ethylene content of linear ethylene / propylene random copolymer portion:
The ethylene content of the linear ethylene / propylene random copolymer portion in Component A-1 used in the present invention is determined from the following formula using the values described above.
Ethylene content (% by weight) of linear ethylene / propylene random copolymer portion = (W ₄₀ × A ₄₀ + W ₁₀₀ × A ₁₀₀ ) / Wc
[Wc is the ratio (% by weight) of the linear ethylene / propylene random copolymer portion determined previously. ]

(6) Die swell ratio:
The die swell ratio of component A-1 used in the present invention is a value determined by the following method.
Set the in-cylinder temperature of the MFR meter to 190 ° C. The orifice has a length of 8.00 mm, a diameter of 1.00 mmφ, and L / D = 8. Also, place a graduated cylinder with ethyl alcohol directly under the orifice (the distance between the orifice and the ethyl alcohol liquid surface is 20 ± 2 mm). In this state, the sample is put into the cylinder, and the load is adjusted so that the extrusion amount per minute becomes 0.10 ± 0.03 g. The extrudate after 6 to 7 minutes is dropped into ethanol and solidified before being collected. The maximum and minimum values of the diameter of the strand-shaped sample of the collected extrudate were measured at 3 locations, 1 cm from the top, 1 cm from the bottom, and the center. Ratio.
The die swell ratio of component A-1 is determined by, for example, performing polymerization in a hydrogen atmosphere of as low a concentration as possible or in a state substantially free of hydrogen at the time of polymerization of the constituent linear ethylene / propylene random copolymer portion. It can be adjusted by controlling the molecular weight high.

(7) Strain hardenability:
The strain hardening property of Component A-1 used in the present invention is measured by the following method.
(A) Apparatus: Ales manufactured by Rheometrics
(B) Jig: EXTENSIONAL VISUALITY FIXTURE, manufactured by TA Instruments
(C) Test temperature: 180 ° C
(D) Strain rate: 1.0 / sec
(E) Sample test piece: press-molded sheet of 15 mm × 10 mm, thickness 0.5 mm

(F) Determination of the presence or absence of strain hardening:
The elongational viscosity at a strain rate of 1.0 / sec is plotted as a logarithmic graph of the amount of strain on the horizontal axis and the elongational viscosity ηE (Pa · s) on the vertical axis. As the amount of strain increases, the extensional viscosity gradually increases, and when the rate of increase in the extensional viscosity increases abruptly from a certain amount of strain, this is a case where strain hardening is exhibited. The case was made “strain hard”. On the other hand, the case where the above-mentioned phenomenon was not substantially recognized was set as “no strain”.
(G) Calculation method of strain hardening degree (λmax):
On the above logarithmic graph, the viscosity immediately before the strain hardening is approximated by a straight line, and the maximum value (ηmax) of the extension viscosity ηE until the strain amount becomes 4.0 is obtained. The viscosity on the approximate line is ηlin. ηmax / ηlin is defined as λmax.
The strain rate can be measured in the range of 0.001 / sec to 10.0 / sec, and the strain hardening degree varies depending on the difference in strain rate.

(8) Shear stress (SS) and first normal stress difference (N1):
The ratio (N1 / SS) between the first normal stress difference (N1) and the shear stress (SS) of component A-1 used in the present invention is determined by the following method.
Using a dynamic viscoelasticity measuring device (“ARES” manufactured by TA Instruments), a steady flow measurement is performed by rotating a cone plate having a diameter of 25 mm and a cone angle of 0.1 radians at a temperature of 180 ° C. and a strain rate of 10 / sec. The values of the shear stress and the first normal stress difference at the time of 100 s are defined as the shear stress (SS) and the first normal stress difference (N1), respectively.

(9) Intrinsic viscosity [η] _{copy of the} linear ethylene / propylene random copolymer portion:
The intrinsic viscosity [eta] _copoly of linear ethylene-propylene random copolymer portion in the component A-1 used in the present invention is determined as follows.
First, after completion of the polymerization of the linear propylene polymer part, a part is sampled from the polymerization tank, and the intrinsic viscosity [η] _{homo of the part} is measured.
Next, after polymerizing the linear propylene polymer portion, the intrinsic viscosity [η] _F of the final polymer (F) obtained by polymerizing the linear ethylene / propylene random copolymer portion is measured. This measurement is performed at a temperature of 135 ° C. using decalin as a solvent using an Ubbelohde viscometer. [Η] _copy is obtained from the following relationship.
[Η] _F = (100−Wc) / 100 × [η] _homo + Wc / 100 × [η] _copy

(10) Molecular weight distribution value of component A-1 (Mw / Mn):
Mw / Mn of component A-1 used in the present invention is the total molecular weight of component A-1 prepared by synthesizing the molecular weight distribution curves of fractions 1 to 3 measured by gel permeation chromatography in the cross fractionator. Obtained from the distribution curve. The method for calculating the weight average molecular weight (Mw) and the number average molecular weight (Mn) from this molecular weight distribution curve is Mw / Mn as a molecular weight distribution value (sometimes referred to as Q value) according to a known method.

(11) Identification of component (BA) and component (BB) in component B:
A technique for evaluating the crystallinity distribution of a propylene-ethylene random copolymer by temperature-temperature elution fractionation (TREF, hereinafter, also simply referred to as TREF) is well known to those skilled in the art. Detailed measurement methods are shown.
G. Glockner, J. et al. Appl. Polym. Sci. : Appl. Polym. Symp. 45, 1-24 (1990)
L. Wild, Adv. Polym. Sci. 98, 1-47 (1990)
J. et al. B. P. Soares, A .; E. Hamielec, Polymer; 36, 8, 1639-1654 (1995)
Identification of component (BA), component (BB), and the like in component B used in the present invention is based on TREF.
A specific method will be described using the figure showing the elution amount and elution amount integration by TREF in FIG. In the TREF elution curve (plot of elution amount with respect to temperature), components (BA) and (BB) show their elution peaks at T (A) and T (B), respectively, due to the difference in crystallinity. Is sufficiently large so that separation is possible at an intermediate temperature T (C) (= {T (A) + T (B)} / 2).

In addition, the lower limit of the TREF measurement temperature is −15 ° C. in the apparatus used in this measurement, but in the present measurement method when the crystallinity of the component (BB) is very low or an amorphous component, There is a case where no peak is shown in the measurement temperature range (in this case, the concentration of the component (BB) dissolved in the solvent is detected at the lower limit of the measurement temperature (ie, −15 ° C.)).
At this time, T (B) is considered to exist below the measurement temperature lower limit, but the value cannot be measured. In such a case, T (B) is the measurement temperature lower limit − It is defined as 15 ° C.
Here, if the integrated amount of the components eluted up to T (C) is defined as W (B) wt%, and the integrated amount of the component eluted at T (C) or higher is defined as W (A) wt%, W (B) Corresponds almost to the amount of the low-crystalline or amorphous component (BB), and the integrated amount W (A) of the component eluted at T (C) or higher is a component with relatively high crystallinity ( It almost corresponds to the amount of B-A). The elution amount curve obtained by TREF and the above-described methods for calculating the various temperatures and amounts obtained therefrom are performed as illustrated in FIG.

(A) TREF Measuring Method In the present invention, TREF is specifically measured as follows.
A sample is dissolved in ODCB (containing 0.5 mg / mL BHT) at 140 ° C. to obtain a solution. This is introduced into a 140 ° C. TREF column, cooled to 100 ° C. at a rate of 8 ° C./min, subsequently cooled to −15 ° C. at a rate of 4 ° C./min, and held for 60 minutes. Then, ODCB (containing 0.5 mg / mL BHT) as a solvent is allowed to flow through the column at a flow rate of 1 mL / min, and components dissolved in ODCB at −15 ° C. are eluted for 10 minutes in the TREF column. The column is linearly heated to 140 ° C. at a rate of 100 ° C./hour to obtain an elution curve.
The outline of the apparatus is as follows.
TREF column: 4.3 mmφ × 150 mm stainless steel column Column filler: 100 μm Surface inactive glass beads Heating method: Aluminum heat block Cooling method: Peltier element (Peltier element is cooled by water)
Temperature distribution: ± 0.5 ° C
Temperature controller: Chino Corporation Digital Program Controller KP1000 (Valve Oven)
Heating method: Air bath oven Measurement temperature: 140 ° C
Temperature distribution: ± 1 ° C
Valve: 6-way valve 4-way valve Injection method: Loop injection method Detector: Fixed wavelength infrared detector MIRAN 1A manufactured by FOXBORO
Detection wavelength: 3.42 μm
High-temperature flow cell: Micro flow cell for LC-IR Optical path length 1.5 mm Window shape 2φ × 4 mm long round Synthetic sapphire window Sample concentration: 5 mg / mL
Sample injection volume: 0.1 mL

(B) Specificity of ethylene content in component (BA) and component (BB) (A) Separation of component (BA) and component (BA):
Based on T (C) obtained by the previous TREF measurement, soluble (component (BA)) and T (C) in T (C) by a temperature rising column fractionation method using a preparative fractionator And insoluble (component (BA)), and the ethylene content of each component is determined by NMR.
The temperature rising column fractionation method refers to a measurement method disclosed in, for example, Macromolecules, 21 314 to 319 (1988). Specifically, the following method was used in the present invention.

(B) Sorting conditions:
A cylindrical column having a diameter of 50 mm and a height of 500 mm is packed with a glass bead carrier (80 to 100 mesh) and maintained at 140 ° C.
Next, 200 mL of a sample ODCB solution (10 mg / mL) dissolved at 140 ° C. is introduced into the column. Thereafter, the temperature of the column is cooled to 0 ° C. at a rate of temperature decrease of 10 ° C./hour. After holding at 0 ° C. for 1 hour, the column temperature is heated to T (C) at a heating rate of 10 ° C./hour and held for 1 hour. Note that the temperature control accuracy of the column through a series of operations is ± 1 ° C.
Next, while maintaining the column temperature at T (C), 800 mL of ODCB of T (C) is flowed at a flow rate of 20 mL / min to elute and recover components soluble in T (C) existing in the column. To do.
Next, the column temperature is increased to 140 ° C. at a rate of temperature increase of 10 ° C./min, and left at 140 ° C. for 1 hour, and then 800 mL of a 140 ° C. solvent (ODCB) is flowed at a flow rate of 20 mL / min, whereby T (C ) To elute and collect insoluble components.
The solution containing the polymer obtained by fractionation is concentrated to 20 mL using an evaporator and then precipitated in 5 times the amount of methanol. The precipitated polymer is recovered by filtration and then dried overnight in a vacuum dryer.

(C) Measurement of ethylene content by ¹³ C-NMR:
The ethylene content of each of the component (BA) and the component (BB) obtained by the fractionation is determined by analyzing a ¹³ C-NMR spectrum measured according to the following conditions by the proton complete decoupling method. .
Model: GSX-400 manufactured by JEOL Ltd. or equivalent device (carbon nuclear resonance frequency of 100 MHz or more)
Solvent: ODCB / heavy benzene = 4/1 (volume ratio)
Concentration: 100 mg / mL
Temperature: 130 ° C
Pulse angle: 90 °
Pulse interval: 15 seconds Integration count: 5,000 times or more The attribution of the spectrum may be performed with reference to, for example, Macromolecules, 17 1950 (1984). The attribution of spectra measured under the above conditions is as shown in the table below. In the table, symbols such as S _αα are in accordance with the notation of Carman et al. (Macromolecules, 10536 (1977)), P represents a methyl carbon, S represents a methylene carbon, and T represents a methine carbon.

Hereinafter, when “P” is a propylene unit in a copolymer chain and “E” is an ethylene unit, six kinds of triads of PPP, PPE, EPE, PEP, PEE, and EEE may exist in the chain. As described in Macromolecules, 15 1150 (1982), the concentration of these triads and the peak intensity of the spectrum are linked by the following relational expressions (1) to (6).
[PPP] = k × I (T _ββ ) (1)
[PPE] = k × I (T _βδ ) (2)
[EPE] = k × I (T _δδ ) (3)
[PEP] = k × I (S _ββ ) (4)
[PEE] = k × I (S _βδ ) (5)
[EEE] = k × [I (S _δδ ) / 2 + I (S _γδ ) / 4} (6)
Here, [] indicates the fraction of triads, for example, [PPP] is the fraction of PPP triads in all triads.
Therefore, [PPP] + [PPE] + [EPE] + [PEP] + [PEE] + [EEE] = 1 (7).
Further, k is a constant, I indicates the spectral intensity, and for example, I (T _ββ ) means the intensity of the peak at 28.7 ppm attributed to T _ββ .

By using the relational expressions (1) to (7) above, the fraction of each triad is obtained, and the ethylene content is obtained from the following expression.
Ethylene content (mol%) = ([PEP] + [PEE] + [EEE]) × 100
Note that the propylene random copolymer according to the present invention contains a small amount of propylene heterogeneous bonds (2,1-bonds and / or 1,3-bonds), thereby producing the following minute peaks.

In order to obtain an accurate ethylene content, it is necessary to include these peaks derived from heterogeneous bonds in the calculation, but it is difficult to completely separate and identify the peaks derived from heterogeneous bonds. Since it is a small amount, the ethylene content in the present invention is determined using the relational expressions (1) to (7), as in the analysis of the copolymer produced with a Ziegler catalyst that does not substantially contain heterogeneous bonds. I will do it.
Conversion from mol% to wt% of ethylene content is performed using the following formula.
Ethylene content (% by weight) = (28 × X / 100) / {28 × X / 100 + 42 × (1−X / 100)} × 100
Here, X is the ethylene content in mol%. The ethylene content [E] W of the entire propylene-ethylene block copolymer is the ethylene content [E] A and [E] B of each of the component (BA) and the component (BB) measured from the above. And the weight ratio W (A) and W (B) weight% of each component calculated from TREF, and is calculated by the following formula.
[E] W = {[E] A × W (A) + [E] B × W (B) / 100 (% by weight)

(12) Melting peak temperature (Tm):
Using a differential scanning calorimeter (DSC) manufactured by Seiko Co., Ltd., a sample of 5.0 mg was taken, held at 200 ° C. for 5 minutes, crystallized to 40 ° C. at a cooling rate of 10 ° C./minute, and further increased by 10 ° C./minute Melt at a warm speed and measure.

(13) Molecular weight distribution value of component B (Mw / Mn):
The molecular weight distribution value (Mw / Mn) of component B is obtained by measurement by gel permeation chromatography (GPC).
Conversion from the retention volume to the molecular weight is performed using a calibration curve prepared in advance with standard polystyrene.

The standard polystyrenes used are all the following brands manufactured by Tosoh Corporation.
F380, F288, F128, F80, F40, F20, F10, F4, F1, A5000, A2500, A1000
A calibration curve is prepared by injecting 0.2 ml of a solution dissolved in ODCB (containing 0.5 mg / ml BHT) so that each is 0.5 mg / ml.
The calibration curve uses a cubic equation obtained by approximation by the least square method. The following numerical values are used for [η] = K × M ^α in the viscosity formula used for conversion to molecular weight.
PS: K = 1.38 × 10 ⁻⁴ α = 0.7
PP: K = 1.03 × 10 ⁻⁴ α = 0.78
The measurement conditions for GPC are as follows.
Apparatus: GPC manufactured by WATERS (ALC / GPC 150C)
Detector: MIRAN 1A IR detector manufactured by FOXBORO (measurement wavelength: 3.42 μm)
Column: AD806M / S (3 pieces) manufactured by Showa Denko KK
Mobile phase solvent: ODCB
Measurement temperature: 140 ° C
Flow rate: 1.0 ml / min
Injection volume: 0.2ml
Sample preparation: Prepare a 1 mg / ml solution using ODCB (containing 0.5 mg / ml BHT) and dissolve at 140 ° C. for about 1 hour.

(14) the peak of the tan δ curve;
It is measured by the solid viscoelasticity measurement described above. The sample used is a 10 mm width × 18 mm length × 2 mm thickness strip cut out from a 2 mm thick sheet formed by injection molding under the following conditions.
As the apparatus, ARES manufactured by Rheometric Scientific is used.
Standard number: JIS-7152 (ISO294-1)
Molding machine: TU-15 injection molding machine manufactured by Toyo Machine Metal Co., Ltd. Molding machine set temperature: 80, 80, 160, 200, 200, 200 ° C. from below the hopper
Mold temperature: 40 ℃
Injection speed: 200 mm / sec (speed in the mold cavity)
Injection pressure: 800 kgf / cm ²
Holding pressure: 800 kgf / cm ²
Holding time: 40 seconds Mold shape: Flat plate (thickness 2mm, width 30mm, length 90mm)

2. Material (1) Linear propylene / ethylene block copolymer (component A-1)
(A-1a): Polymerized with Ziegler-based catalyst, MFR (230 ° C., 2.16 kg load) of the linear propylene polymer portion is 294 g / 10 min, component of the linear ethylene / propylene random copolymer portion The ratio to the entire A-1 is 7.2% by weight, the MFR of the entire component A-1 (230 ° C., 2.16 kg load) is 102 g / 10 minutes, and the die swell ratio of the entire component A-1 is 1.6. Shows strain hardening in 180 ° C. extensional viscosity measurement (strain hardening “Yes”), its strain hardening degree (λmax) is 3.71, and shear stress in transient response measurement at 180 ° C. strain rate of 10 / sec. the first normal stress difference relative (SS) (N1) ratio (N1 / SS) is 2.17, furthermore, intrinsic viscosity _{[eta] copoly} of linear ethylene-propylene random copolymer portion 7. 3dl / g Component A-1 overall molecular weight distribution value (Mw / Mn) is 8.1, linear ethylene / propylene random copolymer portion has an ethylene content of 36% by weight (measured by cross fractionation method), linear ethylene / propylene A linear propylene / ethylene block copolymer (antioxidant / neutralizing agent, added pellets) having a random copolymer portion Mw of 1,220,000 (cross fractionation GPC measurement).

(A-1b): Polymerized with a Ziegler-based catalyst, MFR (230 ° C., 2.16 kg load) of the linear propylene polymer portion is 615 g / 10 min, component of the linear ethylene / propylene random copolymer portion The ratio to the whole A-1 is 9.3 wt%, the MFR of the whole component A-1 (230 ° C., 2.16 kg load) is 153 g / 10 minutes, and the die swell ratio of the whole component A-1 is 1.7. Shows strain hardening in 180 ° C. extensional viscosity measurement (strain hardening “Yes”), has a strain hardening degree (λmax) of 7.43, and shear stress in transient response measurement at 180 ° C. strain rate of 10 / sec. the first normal stress difference relative (SS) (N1) ratio (N1 / SS) is 2.81, furthermore, intrinsic viscosity _{[eta] copoly} of linear ethylene-propylene random copolymer portion 9. 4 dl / g The molecular weight distribution value of Component A-1 as a whole is 12.0, the ethylene content of the linear ethylene / propylene random copolymer portion is 27% by weight (measured by a cross fractionation method), and the linear ethylene / propylene random copolymer portion is The linear propylene / ethylene block copolymer (antioxidant / neutralizing agent, added pellet) having an Mw of 1.870,000 (cross fractional GPC measurement).

(2) Propylene polymer (component A-2)
(A-2a): Polymerized with a Ziegler catalyst, MFR of component A-2 as a whole (230 ° C., 2.16 kg load) is 32 g / 10 minutes, relative to component A-2 of ethylene / propylene random copolymer portion as a whole Propylene / ethylene block copolymer (antioxidant) having a proportion of 15.1% by weight and an ethylene / propylene random copolymer portion having an ethylene content of 51% by weight (cross fractionation method: measured by the same method as component A-1) Agent, neutralizer, added pellets).

(A-2b): Polymerized with Ziegler catalyst, MFR of component A-2 as a whole (230 ° C., 2.16 kg load) is 98 g / 10 min, relative to component A-2 of ethylene / propylene random copolymer portion as a whole Propylene / ethylene block copolymer (antioxidant) having a proportion of 19.9% by weight and an ethylene content of the ethylene / propylene random copolymer portion of 37% by weight (cross fractionation method: measured by the same method as component A-1) Agent, neutralizer, added pellets).

(3) Propylene / ethylene block copolymer (component B)
(B-1): Polymerized with a metallocene catalyst, 50% by weight of a propylene-ethylene random copolymer component (BA) having an ethylene content of 1.5% by weight in the first step, and a component (B It is obtained by sequential polymerization of 50% by weight of a propylene-ethylene random copolymer component (BB) containing 10% by weight of ethylene more than -A). (16 kg load) has a single peak at 5.9 g / 10 min, melting peak temperature (Tm) of 140 ° C., molecular weight distribution value (Mw / Mn) of 2.7, and tan δ curve of −12.3 ° C. A propylene / ethylene block having an ethylene content of component (BA) of 1.5% by weight, an ethylene content of component (BB) of 11.5% by weight, and an overall ethylene content of component B of 13% by weight Copolymer (antioxidant, neutralization - nucleating agent, additive already pellets).

(4) Ethylene elastomer (component C)
(C-1): Ethylene / octene copolymer elastomer (Dow Chemical Japan, Engage 8407, MFR (190 ° C., 2.16 kg load) 30 g / 10 min, octene content 40% by weight).

(5) Foaming agent (component D)
(D-1): 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 bicarbonate -Citric acid based, low density polyethylene base.

(6) Filler (component E)
(E-1): Talc (manufactured by Fuji Talc Industrial Co., Ltd., average particle size 5.3 μm, average aspect ratio 6).

(7) Elastomers other than ethylene elastomer (component C) (component F)
(F-1): Hydrogenated styrene-butadiene elastomer (HSBR) (manufactured by JSR, Dynalon 1320P, MFR (230 ° C., 2.16 kg load) 3.5 g / 10 min, styrene content 10% by weight).

3. Examples and Comparative Examples [Examples 1 to 7, Comparative Examples 1 to 5]
(1) Manufacture of a polypropylene resin composition Component A-1, Component A-2, Component B, Component C, Component E and Component F are blended in the proportions shown in Table 3 (excluding Component D). The mixture was kneaded and granulated under the following conditions.
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 polypropylene-based resin composition Component D was further added to the above kneaded and granulated composition, blended in the proportions shown in Table 3, and molded under the following conditions.
Injection molding machine: “α-300” manufactured by FANUC.
Mold: 400 mm long × 200 mm wide, having a flat plate-shaped cavity with variable thickness by adjusting the position of the movable mold, and its initial cavity clearance (T0) is 1.3 mm.
Molding conditions: cylinder temperature 210 ° C., mold temperature 40 ° C., injection rate 65% / second, cooling time 30 seconds.
Molding method: mold opening injection foaming in which the initial cavity clearance (T0) is 1.3 mm and the post core back cavity clearance (T1) is 3.5 mm.
However, as described above, the Charpy impact strength test piece was an injection molding machine (Toshiba Machine) using the kneading and granulating composition (excluding the foaming agent (component D)) with a clamping pressure of 80 tons. It was molded under the conditions of a molding temperature of 200 ° C and a mold temperature of 40 ° C.

(3) Evaluation Performance evaluation was performed on the above molded product. The results are shown in Table 4.

From the results shown in Tables 3 and 4, the polypropylene resin compositions and injection-foamed molded articles having the compositions shown in Examples 1 to 7 that satisfy the respective requirements in the essential constituent elements of the present invention are both surface appearance and impact strength. Excellent in injection foaming moldability.
All of these can be significantly reduced in weight, are excellent in recyclability and environmental adaptability, and are automotive parts, industrial parts including television parts and other home appliances, parts of electronic products, building material parts, preferably automobile parts. In particular, it has become clear that it has performance suitable for automobile interior parts such as trims, ceiling materials, trunks, instrument panels, pillars and the like.

On the other hand, the polypropylene resin compositions and injection-foamed molded articles having the compositions shown in Comparative Examples 1 to 5 are inferior because of their poor performance balance.
For example, (1) Comparative Example 1 did not contain Component B and Component C, and therefore there was a significant difference from Examples 2 and 3 in surface appearance and impact strength. This indicates that component B and component C are essential to meet the requirements of the present invention.
(2) Since Comparative Example 2 did not contain Component B, significant differences from Example 3 occurred in surface appearance, impact strength, and injection foaming moldability (foaming ratio and cell form). This indicates that component B is essential to meet the requirements of the present invention.
(3) Since Comparative Example 3 and Comparative Example 4 did not contain Component C, a significant difference from Example 3 occurred in impact strength. This indicates that it is essential that component C meets the requirements of the present invention.
(4) Since the comparative example 5 does not contain the component A-1 such that the ratio (N1 / SS) of the first normal stress difference (N1) to the shear stress (SS) is 1.01 or more, the surface appearance In addition, a significant difference from Example 7 occurred in injection foaming moldability (surface tension and foaming ratio). This indicates that it is essential that component A meets the requirements of the present invention.
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 polypropylene resin composition and injection-foamed molded article of the present invention have excellent surface appearance, good impact strength and injection-foaming moldability, and can be significantly reduced in weight even under a low injection rate (injection speed). Because of its excellent recyclability and environmental adaptability, industrial parts including automobile parts, household appliances such as TV sets, electronic product parts, etc., preferably automobile parts, especially trim parts, ceiling materials, trunks, instruments It can be suitably used for automobile interior parts such as a reinforcement panel and a pillar.

Claims (9)

A linear propylene / ethylene block copolymer comprising a linear propylene polymer portion and a linear ethylene / propylene random copolymer portion and having the following characteristics (A-1-i) to (A-1-vi): A polypropylene resin (component A) composed of 30 to 100% by weight of a polymer (component A-1) and another propylene polymer (component A-2) of 0 to 70% by weight, and the following conditions (Bi ) To (Bv), a propylene-ethylene block copolymer (component B), an ethylene elastomer (component C), and a foaming agent (component D). The content of component C is 1 to 40% by weight based on 100% by weight of the total amount of A, B and C, and the content of component C is 1 to 40% with respect to 100% by weight of the total amount of components A, B and C. % Polyp Pyrene-based resin composition.
Characteristic (A-1-i): The melt flow rate (230 ° C., 2.16 kg load) of the linear propylene polymer portion is 130 g / 10 min or more.
Characteristic (A-1-ii): The ratio of the linear ethylene / propylene random copolymer portion to the entire linear propylene / ethylene block copolymer (component A-1) is 2 to 50% by weight.
Characteristic (A-1-iii): Melt flow rate (230 ° C., 2.16 kg load) exceeds 60 g / 10 min.
Characteristic (A-1-iv): Die swell ratio is 1.2 to 2.5.
Characteristic (A-1-v): Shows strain hardening in 180 ° C. extensional viscosity measurement.
Characteristic (A-1-vi): The ratio (N1 / SS) of the first normal stress difference (N1) to the shear stress (SS) in the melt viscoelasticity measurement is 1.01 or more.
Condition (Bi): 30 to 95% by weight of propylene alone or a propylene-ethylene random copolymer component (BA) having an ethylene content of 7% by weight or less in the first step using a metallocene catalyst. Propylene- obtained by sequentially polymerizing 70 to 5 wt% of a propylene-ethylene random copolymer component (BB) containing 3 to 20 wt% more ethylene than component (BA) in the process It must be an ethylene block copolymer.
Condition (B-ii): The melt flow rate (230 ° C., 2.16 kg load) is in the range of 0.5 to 100 g / 10 minutes.
Condition (B-iii): The melting peak temperature (Tm) measured by the DSC method is in the range of 110 to 150 ° C.
Condition (B-iv): The molecular weight distribution value (Mw / Mn) is in the range of 1.5-4.
Condition (Bv): In the temperature-loss tangent curve obtained by solid viscoelasticity measurement, the tan δ curve has a single peak at 0 ° C. or lower. Linear propylene-ethylene block copolymer (Component A-1) has a feature in that the intrinsic viscosity _{[eta] copoly} of linear ethylene-propylene random copolymer portion is 5.3~15dl / g The polypropylene resin composition according to claim 1.   The polypropylene-based resin composition according to claim 1 or 2, wherein the linear propylene / ethylene block copolymer (component A-1) has a molecular weight distribution value (Mw / Mn) of 7 to 13. .   The ethylene content of the linear ethylene / propylene random copolymer portion in the linear propylene / ethylene block copolymer (component A-1) was 15 with respect to the total amount of the linear ethylene / propylene random copolymer portion. The polypropylene resin composition according to any one of claims 1 to 3, wherein the content is -80 wt%.   Furthermore, 1-60 weight part of filler (component E) is contained with respect to 100 weight part of total amounts of component A, B, and C, The any one of Claims 1-4 characterized by the above-mentioned. Polypropylene resin composition.   The polypropylene resin composition according to claim 5, wherein the filler (component E) is at least one selected from talc, polyester fiber, whisker, glass fiber, or carbon fiber.   Furthermore, the elastomer (component F) other than the ethylene-based elastomer (component C) is contained in an amount of 1 to 40 parts by weight with respect to 100 parts by weight of the total amount of the components A, B and C. 7. The polypropylene resin composition according to any one of 6 above.   An injection-foamed molded article comprising the polypropylene resin composition according to any one of claims 1 to 7.   A mold having a mold cavity clearance (T0) smaller than a mold cavity clearance (T1) corresponding to the shape position of the final product, which is composed of a fixed mold and a movable mold capable of moving forward and backward An injection step of injecting and filling a molten or semi-molten polypropylene resin composition into the cavity, and retracting the movable mold to the mold cavity clearance (T1), and expanding the cavity of the mold cavity by the expansion pressure by the foaming agent A mold-opening injection molding method comprising a foaming step for filling, and a method for producing an injection foamed molding comprising a polypropylene resin composition, wherein the molding prior to foaming in the injection step of injection-filling a polypropylene resin composition The molding is performed under a condition that an injection rate with respect to a filling volume of 100% is 20% / second or more. Method for producing injection foam molding.

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