JP7679172B2 - Polypropylene resin composition and molded article obtained therefrom - Google Patents

Description

The present invention relates to a polypropylene resin composition and a molded article obtained therefrom. More specifically, the present invention relates to a polypropylene resin composition that gives a molded article having excellent rigidity and heat resistance and small anisotropy of mold shrinkage rate, and a molded article obtained from this resin composition.

Molded articles obtained by molding polypropylene resin compositions are increasingly being used in a variety of fields, including automobile parts and home appliance parts, due to their excellent moldability and physical properties.

However, as the applications of polypropylene resin compositions expand, the size of the parts to which they are used tends to become larger. When the size of parts increases, problems such as deformation and warping of large parts occur, and effective methods for suppressing these problems are required. It is known that such deformation and warping phenomena are caused by the anisotropy of the shrinkage rate during molding, and methods for suppressing the anisotropy of the molding shrinkage rate are required. In addition, as the size of parts increases, the weight of the parts also increases, so there is also a need for methods for suppressing the anisotropy of the shrinkage rate in lightweight polypropylene resin compositions.

As a method for suppressing deformation and warping of molded bodies, a method of combining a specific polypropylene-based resin composition with an inorganic filler is known. For example, a method of suppressing the anisotropy of rigidity and molding shrinkage rate by combining an inorganic filler such as talc has been disclosed (e.g., Patent Documents 1 and 3). In addition, a method of similarly suppressing the anisotropy of rigidity and molding shrinkage rate by combining wollastonite as an inorganic filler has been disclosed (e.g., Patent Document 2). However, the method of suppressing the anisotropy of shrinkage rate by adding a filler increases the density of the polypropylene-based resin composition, and it cannot be said that it has been able to reduce the weight.

JP 2012-229303 A JP 2015-127405 A JP 2017-019975 A

The present invention seeks to solve problems not solved by the above-mentioned conventional techniques, and aims to provide a polypropylene resin composition that provides molded articles with excellent rigidity and small anisotropy in mold shrinkage rate for use in automobile parts, home appliance parts, etc., and a molded article obtained from this resin composition.

In order to solve the above problems, the inventors conducted extensive research and discovered that a polypropylene resin composition in which a specific propylene homopolymer is blended with a specific ethylene-α-olefin random copolymer in a specific ratio, and a molded article made from the same, can solve the above problems. Based on these findings, the inventors have completed the present invention.

That is, according to the first aspect of the present invention, there is provided a polypropylene resin composition comprising 85 to 99.5% by weight of a component (A) satisfying the following conditions (A-1) and (A-2), and 0.5 to 15% by weight of a component (B) satisfying the following conditions (B-1) to (B-3) (the total of the components (A) and (B) is 100% by weight).
Condition (A-1): Component (A) is a propylene homopolymer having a melt flow rate (MFR, 230°C, 2.16 kg load) in the range of 0.5 to 100 g/10 min.
Condition (A-2): Component (A) exhibits a peak melting temperature (Tm) in the range of 160 to 175°C when measured by the DSC method.
Condition (B-1): Component (B) is a propylene-α-olefin random copolymer (wherein the α-olefin is an α-olefin having 2 to 8 carbon atoms (excluding 3 carbon atoms)), and the content of the α-olefin is 0.1 to 5% by weight (wherein the total of the propylene and α-olefin in component (B) is 100% by weight).
Condition (B-2): The melt flow rate (MFR, 230°C, 2.16 kg load) of component (B) is in the range of 0.5 to 100 g/10 min.
Condition (B-3): Component (B) exhibits a peak melting temperature (Tm) in the range of 110°C or higher and lower than 160°C when measured by a DSC method.

According to the second aspect of the present invention, the polypropylene resin composition according to the first aspect of the present invention is provided, which further contains 0.01 to 0.25 parts by weight of a nucleating agent (C) per 100 parts by weight of the polypropylene resin composition.

According to the third aspect of the present invention, a molded article is provided which is obtained from the polypropylene resin composition of the first or second aspect of the present invention.

The polypropylene resin composition of the present invention and the molded articles made from it have high rigidity and small anisotropy in shrinkage rate, making them suitable for a wide range of applications, including automobile parts and home appliance parts.

The present invention relates to a polypropylene resin composition that contains 85 to 99.5% by weight of a specific component (A) and 0.5 to 15% by weight of a specific component (B), preferably a polypropylene resin composition that contains 0.01 to 0.2 parts by weight of a specific component (C) per 100 parts by weight of the polypropylene resin composition, and a molded article obtained by molding the same.

The following provides detailed explanations of each aspect of the polypropylene resin composition of the present invention, its manufacturing method, and the molded article obtained by molding it.

[1] Constituents of polypropylene resin composition The polypropylene resin composition of the present invention must contain 85 to 99.5% by weight of a component (A) satisfying the conditions (A-1) and (A-2) described below, and 0.5 to 15% by weight of a component (B) satisfying the conditions (B-1) to (B-3) described below (where the sum of components (A) and (B) is taken as 100% by weight). The preferred ranges are 90 to 99.5% by weight of component (A) and 0.5 to 10% by weight of component (B), more preferably 92 to 99% by weight of component (A) and 1 to 8% by weight of component (B), and even more preferably 94 to 96% by weight of component (A) and 4 to 6% by weight of component (B). If the amount of component (B) is less than 0.5% by weight, the shrinkage anisotropy becomes large, whereas if the amount of component (B) exceeds 15% by weight, there is a concern that the rigidity and heat distortion temperature (HDT) will decrease. By setting the amount within the above range, it is possible to obtain a polypropylene resin composition of the present invention that is capable of reducing the shrinkage anisotropy while maintaining a higher rigidity and heat distortion temperature (HDT).

(1) Component (A)
The component (A) used in the present invention is a propylene homopolymer satisfying the conditions (A-1) and (A-2) described below.

(1-1) Condition (A-1): Melt flow rate (MFR)
The melt flow rate (hereinafter sometimes abbreviated as MFR) of the component (A) used in the present invention must be in the range of 0.5 to 100 g/10 min, preferably 3 to 80 g/10 min, more preferably 5 to 60 g/10 min, even more preferably 15 to 55 g/10 min, among which 25 to 50 g/10 min, and particularly preferably 30 to 45 g/10 min. By setting the MFR in the range of 0.5 to 100 g/10 min, the polypropylene resin composition of the present invention has sufficient moldability (fluidity) and can suppress the occurrence of burrs in a molded article obtained by molding the polypropylene resin composition. That is, if the MFR is less than 0.5 g/10 min, the moldability (fluidity) may decrease, and if the MFR is more than 100 g/10 min, burrs may occur during molding.
In this specification, the MFR is a value measured in accordance with JIS K7210 at a test temperature of 230° C. and a load of 2.16 kg.
The MFR of component (A) can be easily adjusted by changing the type of catalyst used in the production, the polymerization temperature or pressure, or, as a general method, by adding a chain transfer agent such as hydrogen during polymerization and adjusting the amount added.

(1-2) Condition (A-2): Melting peak temperature (Tm)
The component (A) used in the present invention must have a melting peak temperature (hereinafter sometimes abbreviated as Tm) measured by DSC (differential scanning calorimetry) in the range of 160°C to 175°C, preferably 162°C to 170°C, more preferably 163°C to 168°C. By setting the melting peak temperature (Tm) in this range, the heat distortion temperature (hereinafter sometimes abbreviated as HDT) and impact strength of the polypropylene resin composition of the present invention and the molded article obtained by molding the same can be in a good range. That is, if the melting peak temperature is 160°C or higher, the HDT of the polypropylene resin composition of the present invention and the molded article obtained by molding the same increases. On the other hand, if the melting peak temperature (Tm) is 175°C or lower, the impact strength and the like can be improved. Also, if the melting peak temperature (Tm) is less than 160°C, the HDT of the polypropylene resin composition of the present invention and the molded article obtained by molding the same tends to decrease. On the other hand, if the melting peak temperature (Tm) exceeds 175°C, the impact strength and other properties may decrease.
In this specification, the melting peak temperature (Tm) was measured using a differential scanning calorimeter (e.g., DSC6200 manufactured by Seiko Instruments Inc.) by taking 5.0 mg of a sample, holding it at 200° C. for 5 minutes, crystallizing it at a temperature drop rate of 10° C./min to 40° C., and further melting it at a temperature increase rate of 10° C./min.
The melting peak temperature (Tm) of component (A) can be controlled, for example, by selecting the type of catalyst used in producing component (A).

(1-3) Density The component (A) used in the present invention preferably has a density in the range of 0.86 to 0.92 g/cm ³ , more preferably 0.863 to 0.915 g/cm ³ , and even more preferably 0.865 to 0.91 g/cm ³ . By setting the density in such a range, it is possible to make both the heat distortion temperature and impact strength of the polypropylene resin composition of the present invention and the molded article made from the same as a raw material good. That is, if the density is less than 0.86 g/cm ³ , the heat distortion temperature of the polypropylene resin composition of the present invention and the molded article made from the same as a raw material tends to decrease, while if the density exceeds 0.92 g/cm ³ , there is a risk of a decrease in impact strength.

(2) Component (B)
The component (B) used in the present invention is a propylene-α-olefin random copolymer satisfying the conditions (B-1) to (B-3) described below.

(2-1) Condition (B-1): α-olefin content The component (B) used in the present invention is a propylene-α-olefin random copolymer, and the α-olefin content must be in the range of 0.1 to 5% by weight, assuming that the total content of propylene and α-olefin in the propylene-α-olefin random copolymer is 100% by weight. The α-olefin is an α-olefin having 2 to 8 carbon atoms (excluding α-olefins having 3 carbon atoms).
The content of the α-olefin is preferably 0.2 to 4.5% by weight, more preferably 0.25 to 4% by weight, and particularly preferably 0.3 to 3.5% by weight. When the content of the α-olefin is within the above range, the polypropylene resin composition of the present invention and the molded article made from the same can have good HDT and impact strength. That is, when the content of the α-olefin is less than 0.1% by weight, the impact strength tends to decrease, and when the content exceeds 5% by weight, the heat distortion temperature (HDT) may deteriorate.
In order to control the α-olefin content within a predetermined range, the ratio of the amounts of propylene and α-olefin fed to the polymerization tank during the production of component (B) may be appropriately adjusted. The relationship between the feed ratio and the α-olefin content in the resulting propylene-α-olefin random copolymer is a technical matter well known to those skilled in the art. For example, when a metallocene catalyst is used, the feed ratio can be adjusted to produce component (B) having the required α-olefin content, although this varies depending on the type of metallocene catalyst.

Examples of the α-olefin having 2 to 8 carbon atoms, excluding 3 carbon atoms (propylene), used in component (B) include ethylene, 1-butene, 2-methyl-1-propene, 1-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 1-hexene, 2-ethyl-1-butene, 2,3-dimethyl-1-butene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3,3-dimethyl-1-butene, 1-heptene, methyl-1-hexene, dimethyl-1-pentene, ethyl-1-pentene, trimethyl-1-butene, and 1-octene.
The comonomer, which is an α-olefin having 2 to 8 carbon atoms excluding 3 carbon atoms (propylene) to be copolymerized with propylene, may be used alone or in combination of two or more kinds.

Specific examples of the propylene-α-olefin random copolymer, component (B), include binary copolymers such as propylene-ethylene random copolymer, propylene-butene-1 random copolymer, propylene-pentene-1 random copolymer, propylene-hexene-1 random copolymer, and propylene-octene-1 random copolymer, and ternary copolymers such as propylene-ethylene-butene-1 random copolymer and propylene-ethylene-hexene-1 random copolymer. Propylene-ethylene random copolymer and propylene-ethylene-butene-1 random copolymer are preferred, with propylene-ethylene random copolymer being particularly preferred because of its excellent balance of physical properties and ease of availability.

(2-2) Condition (B-2): Melt flow rate (MFR)
The melt flow rate of the component (B) used in the present invention must be in the range of 0.5 to 100 g/10 min, preferably 3 to 80 g/10 min, more preferably 5 to 50 g/10 min. By setting the MFR in the range of 0.5 to 100 g/10 min, the polypropylene resin composition of the present invention has sufficient moldability (fluidity) and can suppress the generation of burrs in a molded article obtained by molding the polypropylene resin composition. That is, if the MFR is less than 0.5 g/10 min, the moldability (fluidity) may decrease, and if the MFR is more than 100 g/10 min, burrs may occur during molding.
The MFR of component (B) can be easily adjusted by changing the type of catalyst used in the production, the polymerization temperature or pressure, or, as a general method, by adding a chain transfer agent such as hydrogen during polymerization and adjusting the amount added.

(2-3) Condition (B-3) Melting peak temperature (Tm)
The component (B) used in the present invention must have a melting peak temperature measured by DSC (differential scanning calorimetry) in the range of 110°C or more and less than 160°C, preferably 115°C to 159°C, more preferably 120°C to 157°C, even more preferably 125°C to 157°C, and particularly preferably 130°C to 155°C. By having the Tm peak in this range, the HDT and impact strength of the polypropylene resin composition of the present invention and the molded article obtained by molding the same can be in a good range. That is, if Tm is 110°C or more, the HDT of the polypropylene resin composition of the present invention and the molded article obtained by molding the same increases. On the other hand, if Tm is less than 160°C, the impact strength and the like can be improved. Also, if Tm is less than 110°C, the HDT of the polypropylene resin composition of the present invention and the molded article obtained by molding the same tends to decrease. On the other hand, if Tm is 160°C or more, there is a risk of the impact strength and the like decreasing.
Furthermore, Tm can be controlled by, for example, appropriately adjusting the ratio of the amounts of propylene and α-olefin fed to a polymerization tank when producing component (B). In order to control Tm to, for example, 110°C or higher and lower than 160°C, it is possible to produce component (B) having the desired Tm by adjusting the α-olefin content to about 0.1 to 5% by weight, although this depends on the type of catalyst used.

(2-4) Density The component (B) used in the present invention preferably has a density in the range of 0.86 to 0.92 g/cm ³ , more preferably 0.863 to 0.915 g/cm ³ , and even more preferably 0.865 to 0.91 g/cm ³ . By setting the density in such a range, it is possible to make both the heat distortion temperature and impact strength of the polypropylene resin composition of the present invention and the molded article made from the same as a raw material good. That is, if the density is less than 0.86 g/cm ³ , the heat distortion temperature of the polypropylene resin composition of the present invention and the molded article made from the same as a raw material tends to decrease, while if the density exceeds 0.92 g/cm ³ , there is a risk of a decrease in impact strength.

(3) Method for Producing Component (A) and Component (B) The method for producing component (A) and component (B) is not particularly limited as long as it is possible to obtain a polymer satisfying the conditions (A-1) to (A-2) and the conditions (B-1) to (B-3), and they can be produced by a known production method.
The catalyst used to obtain the components (A) and (B) used in the present invention is not particularly limited, and known catalysts can be used. For example, a so-called Ziegler-Natta catalyst that combines a titanium compound and an organoaluminum (for example, as described in "Polypropylene Handbook" (first edition, first printing published May 15, 1998)) or a metallocene catalyst (for example, as described in JP-A-5-295022) can be used.

In particular, it is preferable to use a metallocene catalyst in the production of component (B) used in the present invention. In other words, it is preferable that the propylene-α-olefin random copolymer (B) used in the present invention is a metallocene-based random copolymer.

The polymerization process used to obtain the component (A) and the component (B) used in the present invention is not particularly limited, and a known polymerization process can be used. For example, a slurry polymerization method, a bulk polymerization method, a gas phase polymerization method, etc. can be used. In addition, either a batch polymerization method or a continuous polymerization method can be used, and if desired, a multi-stage continuous polymerization method such as a two-stage or three-stage method can be used. In addition, it can also be produced by mechanically melt-kneading two or more kinds of propylene-based polymers.
In addition, various polypropylene resins that can be used as components (A) and (B) are commercially available from many companies, and examples of products that can be used as component (A) include the Novatec series manufactured by Japan Polypropylene Corporation, and products that can be used as component (B) include the Wintech series manufactured by Japan Polypropylene Corporation. It is also possible to purchase and use a product having the desired physical properties from these commercially available products.

(4) Nucleating Agent (C)
The polypropylene resin composition of the present invention preferably further contains 0.01 to 0.25 parts by weight of a nucleating agent (C) (hereinafter, sometimes simply referred to as component (C)) relative to 100 parts by weight of the polypropylene resin composition. The amount of component (C) relative to 100 parts by weight of the polypropylene resin composition is preferably in the range of 0.03 to 0.23 parts by weight, more preferably 0.05 to 0.22 parts by weight, and even more preferably 0.08 to 0.21 parts by weight. By setting the amount of component (C) in the range of 0.01 to 0.25 parts by weight, the effect of increasing the heat distortion temperature (hereinafter, sometimes abbreviated as HDT) of the molded article can be obtained. That is, if the amount of component (C) is less than 0.01 part by weight, the effect of increasing the heat distortion temperature of the molded article may not be obtained. On the other hand, if the amount of component (C) is more than 0.25 parts by weight, the anisotropy of the shrinkage rate may become large.

Component (C) that can be used in the present invention preferably includes nucleating agents (a) represented by the following formula (1), nucleating agents (b) represented by the following formula (2), nucleating agents (c) represented by the following formula (3), nucleating agents (d) consisting of aromatic carboxylic acid metal salts, and nucleating agents (e) represented by the following formula (4). Component (C) may be used alone or in combination of two or more types.

（式中、Ｒ_１、Ｒ_２及びＲ_３は、互いに独立して、未置換の又は置換された炭化水素基を表す。） The nucleating agent (a) is an aminobenzene compound represented by the following general formula (1).

(In the formula, R ₁ , R ₂ and R ₃ each independently represent an unsubstituted or substituted hydrocarbon group.)

Specific examples of compounds having unsubstituted or substituted hydrocarbon groups include the various compounds shown below. The nucleating agent used in the present invention has a performance that can be properly achieved if it has the form of the compound of formula (1) above. The various compounds having unsubstituted or substituted hydrocarbon groups depend on the reaction components selected when synthesizing the compound represented by formula (1) used in the present invention, and although they have a slight effect on the reaction yield of the compound of formula (1), they act equally as nucleating agents, and specific examples include the following.

Preferred are compounds of formula (1) in which at least one of the groups R ₁ , R ₂ and R ₃ is a branched alkyl group having 3 to 20 carbon atoms or a cycloalkyl group having 3 to 12 carbon atoms which is unsubstituted or substituted by one or more alkyl groups having 1 to 20 carbon atoms.

In addition, the groups R ₁ , R ₂ and R ₃ each independently represent a 1-methylethyl group, a 2-methylpropyl group, a 1-methylpropyl group, a tert-butyl group, a 1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutyl group, a 1,1-dimethylpropyl group, a 1-ethylpropyl group, a tert-butylmethyl group, a cyclopropyl group, a 3-methylcyclopropyl group, a 2,2,3,3-tetramethylcyclopropyl group, a cyclopentyl group, a cyclopentylmethyl group, a 2-cyclopentylethyl group, a cyclohexyl group, a cyclohexylmethyl group, a 2-cyclohexylethyl group, a 4-tert-butylcyclohexyl group, a (4-methylcyclohexyl)methyl group, or any of the groups represented by the following formulae (1-1) to (1-3): More preferred are compounds of formula (1) represented by the functional group α-cyclohexylbenzyl, 3-methylbenzyl, 3,4-dimethoxybenzyl, 4-biphenylmethyl, 2-naphthylmethyl, m-tolyl, m-methoxyphenyl, p-tolyl, 4-ethylphenyl, 4-isopropylphenyl, 4-tert-butylphenyl, 2,3-dimethylphenyl, 2,6-dimethylphenyl, 2,4-dimethylphenyl, 3,4-dimethylphenyl, 3,5-dimethylphenyl, 3,5-di-tert-butylphenyl, 2,4,6-trimethylphenyl or 3,5-di-tert-butyl-4-hydroxyphenyl.

Specifically, the compounds represented by formula (1) include 1,3,5-tris[2,2-dimethylpropionylamino]benzene, 1,3,5-tris[cyclohexylcarbonylamino]benzene, 1,3,5-tris[4-methylbenzoylamino]benzene, 1,3,5-tris[3,4-dimethylbenzoylamino]benzene, 1,3,5-tris[3,5-dimethylbenzoylamino]benzene, 1,3,5-tris[cyclopentanecarbonylamino]benzene, 1,3,5-tris[1-adamantanecarbonylamino]benzene, 1,3,5-tris[2-methylprop propionylamino]benzene, 1,3,5-tris[3,3-dimethylbutyrylamino]benzene, 1,3,5-tris[2-ethylbutyrylamino]benzene, 1,3,5-tris[2,2-dimethylbutyrylamino]benzene, 1,3,5-tris[2-cyclohexyl-acetylamino]benzene, 1,3,5-tris[3-cyclohexyl-propionylamino]benzene, 1,3,5-tris[4-cyclohexyl-butyrylamino]benzene, 1,3,5-tris[5-cyclohexyl-valeroylamino]benzene, 1-isobutyrylamino-3,5-bis[pi 1,3-bis[isobutyrylamino]-5-pivaloylaminobenzene, 1,3-bis[isobutyrylamino]-5-(2,2-dimethyl-butyryl)aminobenzene, 1,3-bis[isobutyrylamino]-5-(3,3-dimethyl-butyryl)aminobenzene, 1,3-bis[2,2-dimethylbutyrylamino]-5-pivaloylaminobenzene, 1,3-bis[2,2-dimethylbutyrylamino]-5-pivaloylaminobenzene, 1,3-bis[2,2-dimethylbutyrylamino]-5-pivaloylaminobenzene, Examples of the 1,3-bis[2,2-dimethylbutyrylamino]-5-isobutyrylaminobenzene, 1,3-bis[3,3-dimethylbutyrylamino]-5-(3,3-dimethylbutyryl)-aminobenzene, 1,3-bis[3,3-dimethylbutyrylamino]-5-pivaloylamino-benzene, 1,3-bis[3,3-dimethylbutyrylamino]-5-isobutyryl-aminobenzene, 1,3-bis[3,3-dimethylbutyrylamino]-5-(2,2-dimethyl-butyrylamino)aminobenzene, or 1,3,5-tris[3-(trimethylsilyl)propionylamino]benzene can be mentioned.

Such compounds can be produced, for example, by the production method described in Published Patent Publication No. 2006-518402.

Of these, compounds of formula (1) in which the groups R ₁ , R ₂ and R ₃ are the same group are preferred, and among these, compounds of formula (1) in which R ₁ , R ₂ and R ₃ are tert-butyl groups, i.e., 1,3,5-tris[2,2-dimethylpropionylamino]benzene, are particularly preferred.

［式中、Ｒ^１は、直接結合、硫黄、炭素数１～９のアルキレン基又は炭素数２～９のアルキリデン基であり、Ｒ^２及びＲ^３は、同一又は異なって、それぞれ水素原子、炭素数１～８のアルキル基又は炭素数７～９のアルキルアリール基であり、ＭはＬｉ、Ｎａ、Ｋ、Ｍｇ、Ｃａ、Ｚｎ又はＡｌであり、ｎはＭの価数である。］ The nucleating agent (b) is an organophosphate metal salt compound represented by the following general formula (2).

[In the formula, R ¹ is a direct bond, sulfur, an alkylene group having 1 to 9 carbon atoms, or an alkylidene group having 2 to 9 carbon atoms; R ² and R ³ are the same or different and each is a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an alkylaryl group having 7 to 9 carbon atoms; M is Li, Na, K, Mg, Ca, Zn, or Al; and n is the valence of M.]

Specific examples of organophosphate metal salt compounds represented by general formula (2) include sodium-2,2'-methylene-bis(4,6-di-t-butylphenyl) phosphate, sodium-2,2'-ethylidene-bis(4,6-di-t-butylphenyl) phosphate, sodium-2,2'-methylene-bis(4-cumyl-6-t-butylphenyl) phosphate, and lithium-2,2'-methylene-bis(4,6-di-t-butylphenyl) phosphate. phosphate, lithium 2,2'-ethylidene-bis(4,6-di-t-butylphenyl)phosphate, lithium 2,2'-methylene-bis(4-cumyl-6-t-butylphenyl)phosphate, sodium 2,2'-ethylidene-bis(4-i-propyl-6-t-butylphenyl)phosphate, lithium 2,2'-methylene-bis(4-methyl-6-t-butylphenyl)phosphate, lithium 2,2'-methylene- Bis(4-ethyl-6-t-butylphenyl)phosphate, sodium-2,2'-butylidene-bis(4,6-di-methylphenyl)phosphate, sodium-2,2'-butylidene-bis(4,6-di-t-butylphenyl)phosphate, sodium-2,2'-t-octylmethylene-bis(4,6-di-methylphenyl)phosphate, sodium-2,2'-t-octylmethylene-bis(4,6-di-t-butylphenyl)phosphate phosphate, sodium 2,2'-methylene-bis(4-methyl-6-t-butylphenyl) phosphate, sodium 2,2'-methylene-bis(4-ethyl-6-t-butylphenyl) phosphate, sodium (4,4'-dimethyl-6,6'-di-t-butyl-2,2'-biphenyl) phosphate, sodium 2,2'-ethylidene-bis(4-s-butyl-6-t-butylphenyl) phosphate, sodium 2,2'-methylene-bis(4,6-dimethylphenyl)phosphate, sodium-2,2'-methylene-bis(4,6-diethylphenyl)phosphate, potassium-2,2'-ethylidene-bis(4,6-di-t-butylphenyl)phosphate, calcium-bis[2,2'-methylene-bis(4,6-di-t-butylphenyl)phosphate], magnesium-bis[2,2'-methylene-bis(4,6-di-t-butylphenyl)phosphate] phenyl) phosphate], zinc bis[2,2'-methylene-bis(4,6-di-t-butylphenyl) phosphate], aluminum tris[2,2'-methylene-bis(4,6-di-t-butylphenyl) phosphate], calcium bis[2,2'-methylene-bis-(4-methyl-6-t-butylphenyl) phosphate], calcium bis[2,2'-ethylidene-bis(4,6-di-t-butylphenyl) phosphate phosphate], calcium bis[2,2'-thiobis(4-methyl-6-t-butylphenyl) phosphate], calcium bis[2,2'-thiobis(4-ethyl-6-t-butylphenyl) phosphate], calcium bis[2,2'-thiobis(4,6-di-t-butylphenyl) phosphate], magnesium bis[2,2'-thiobis(4,6-di-t-butylphenyl) phosphate], magnesium bis[2,2'-thio Examples of such nucleating agents include bis(4-t-octylphenyl)phosphate], calcium bis[(4,4'-dimethyl-6,6'-di-t-butyl-2,2'-biphenyl)phosphate], magnesium bis[2,2'-ethylidene-bis(4,6-di-t-butylphenyl)phosphate], aluminum tris[2,2'-ethylidene-bis(4,6-di-t-butylphenyl)phosphate], and mixtures of two or more of these. Of these, sodium-2,2'-methylene-bis(4,6-di-t-butylphenyl)phosphate is particularly preferred. As such nucleating agents, commercially available products can be used. Specifically, ADEKA Corporation's product name: Adeka STAB NA-11 can be mentioned.

［式中、Ｍ_１及びＭ_２は、いずれもリチウムイオン、ナトリウムイオン若しくはカリウムイオンであるか、又は共同してカルシウム、マグネシウム、ストロンチウム、亜鉛及び一塩基性アルミニウムからなる群より選択される単一の金属カチオンであり、Ｒ_１、Ｒ_２、Ｒ_３、Ｒ_４、Ｒ_５、Ｒ_６、Ｒ_７、Ｒ_８、Ｒ_９及びＲ_１０は、同一又は異なって、水素、ヒドロキシ、フッ素、塩素、臭素、沃素、炭素数１～９のアルキル（ここで、いずれか２つのビシナル（隣接炭素に結合）又はジェミナル（同一炭素に結合）アルキルは、一緒になって６個までの炭素原子を有する炭化水素環を形成してもよい）、炭素数１～９のアルコキシ、炭素数２～９のアルキレンオキシ、フェニル、アミノ及び炭素数１～９のアルキルアミノからなる群からそれぞれ選択される。］ The nucleating agent (c) is a nucleating agent represented by the general formula (3).

[In the formula, M ₁ and M ₂ are each a lithium ion, a sodium ion, or a potassium ion, or are jointly a single metal cation selected from the group consisting of calcium, magnesium, strontium, zinc, and monobasic aluminum, and R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , R ₈ , R ₉ , and R ₁₀ are the same or different and are each selected from the group consisting of hydrogen, hydroxy, fluorine, chlorine, bromine, iodine, alkyl having 1 to 9 carbon atoms (wherein any two vicinal (bonded to adjacent carbons) or geminal (bonded to the same carbon) alkyl may be joined together to form a hydrocarbon ring having up to 6 carbon atoms), alkoxy having 1 to 9 carbon atoms, alkyleneoxy having 2 to 9 carbon atoms, phenyl, amino, and alkylamino having 1 to 9 carbon atoms.]

Here, the term "monobasic aluminum" is well known and is intended to include an aluminum hydroxide group as a single cation with two carbonyloxy groups attached. Furthermore, in each of these possible salts, the configuration of the asymmetric carbon atom may be either cis or trans, with cis being preferred.

The nucleating agent represented by general formula (3) may be mixed with other compounds to prevent aggregation, etc.

ハイパフォームＨＰＮ－２０Ｅの造核剤成分の構造を下記に示す。

As such a nucleating agent, commercially available products can be used. Specific examples include Hyperform HPN68L and Hyperform HPN-20E, both manufactured by Milliken. The structure of the nucleating agent component of Hyperform HPN68L is shown below. Metal represents sodium.

The structure of the nucleating agent component of Hyperform HPN-20E is shown below.

The nucleating agent (d) is an aromatic carboxylic acid metal salt, and a commercially available one having the following formula, trade name: AL-PTBBA, manufactured by Kyodo Yakuhin Co., Ltd., can be mentioned.

［式中、Ｒ^１は、プロパン－１，２，３－トリイル基又はブタン－１，２，３，４－テトライル基を表す。３個又は４個のＲ^２は、互いに同一又は異なって、それぞれ水素原子又は炭素数１～１０の直鎖状若しくは分岐鎖状のアルキル基を表す。ａは、３又は４の整数を表す。］ The nucleating agent (e) is a nucleating agent represented by the formula (4), and a commercially available example thereof is Rikaclear PC-1, manufactured by New Japan Chemical Co., Ltd.

[In the formula, R ¹ represents a propane-1,2,3-triyl group or a butane-1,2,3,4-tetrayl group. Three or four R ^2s may be the same or different and each represents a hydrogen atom or a linear or branched alkyl group having 1 to 10 carbon atoms. a represents an integer of 3 or 4.]

(5) Pigment The polypropylene resin composition of the present invention may contain a pigment within a range that does not impair the effects of the present invention.
Pigments that can be used in the polypropylene resin composition of the present invention include black-based carbon black and iron black; white-based titanium oxide, zinc oxide, litbones, and lead white; blue-based iron blue, ultramarine, cobalt blue, phthalocyanine blue, indanthrene blue RS, fast sky blue lake, alkali blue lake, and Victoria blue lake; red-based red oxide, lead charcoal, molybdenum red, cadmium red, lake red C, lake red D, brilliant carmine 6B, lithol red, permanent red 4R, watching red, thioindigo red, alizarin red, quinacridone red, rhodamine lake, orange lake, benzimidazolone red, pyrazolone red, condensed azo red, perylene red, permanent carmine FB, and quinacridone mazene. Examples of pigments that can be used include yellow lead yellow, cadmium yellow, titanium yellow, iron yellow, isoindolinone yellow, benzidine yellow, fast yellow, flavonethron yellow, naphthol yellow, quinoline yellow, benzimidazolone yellow, HR yellow, and condensed azo yellow; green chrome green, chromium oxide, gyne green, spinel green, phthalocyanine green, pigment green B, naphthol green, acid green lake, and malachite green lake; orange chrome orange, cadmium orange, benzimidazolone orange, and perinone orange; brown zinc ferrite; purple manganese purple, cobalt purple, red iron oxide, fast violet B, methyl violet lake, and dioxazine violet. Pigments that can be used in the range that does not impair the effects of the present invention are preferably small in particle size, and if the particle size of the pigment is too large, poor dispersion may occur on the surface of the molded body.

In the present invention, the amount of pigment is usually 0.01 to 20 parts by weight, preferably 0.025 to 15 parts by weight, more preferably 0.05 to 10 parts by weight, even more preferably 0.075 to 5 parts by weight, and particularly preferably 0.1 to 2 parts by weight, per 100 parts by weight of the polypropylene resin composition. By setting the amount within the above range, it becomes possible to easily adjust the color and obtain good color development. In other words, if the amount of pigment is less than 0.01 parts by weight, the uniformity of the coloring may deteriorate and color unevenness may occur. Furthermore, if the amount exceeds 20 parts by weight, adverse effects on physical properties such as a decrease in rigidity may occur.

The pigment can be directly blended into the polypropylene resin composition, but it is preferable to use it in the form of a masterbatch in terms of the ease of handling the pigment and blending. For example, a masterbatch containing 20 to 80% by weight of pigment can be used, in which the matrix components are polyethylene wax, polyethylene, etc., in addition to component (A) and component (B) used in the polypropylene resin composition.

(6) Optionally Added Components In addition to the above-mentioned components (A), (B), (C) and pigment, optional components may be added to the polypropylene resin composition of the present invention, if necessary, within a range that does not significantly impair the effects of the present invention, for example, to further improve the intended effects or to impart other performance or effects. The amount of the optional components added is usually 0.2 to 2.0% by weight based on the entire polypropylene resin composition.
Specific examples of optional components include antistatic agents such as nonionic ones, light stabilizers such as hindered amine ones, ultraviolet absorbers such as benzotriazole ones, foaming agents such as physical foaming agents, dispersants such as organic metal salts, antioxidants such as phenols, neutralizing agents such as inorganic compounds, lubricants such as fatty acid amides, metal deactivators such as nitrogen compounds, surfactants such as nonionic ones, antibacterial and antifungal agents such as thiazoles, flame retardants such as halogen compounds, fluorescent whitening agents, antifoaming agents (antifoaming agents), crosslinking agents, peroxides, process oils (blended oils), antiblocking agents, plasticizers, polyolefins such as polypropylene other than the above component (A), thermoplastic resins such as polyamides and polyesters, fillers such as small particle size talc, elastomers (rubber-like polymers), and other additives. Two or more of these components may be used in combination, and may be added later to the polypropylene resin composition of the present invention, or may be added to each component, and two or more of each component may be used in combination.

[II] Production of Polypropylene-Based Resin Composition The polypropylene-based resin composition of the present invention can be produced by blending the above-mentioned component (A), component (B), and further, as necessary, component (C) and optional added components such as pigments, in the blending ratio described above, and mixing them by a known method such as a tumbler mixer, super mixer, Henschel mixer, screw blender or ribbon blender, or by kneading and granulating them using a conventional kneading machine such as a single-screw extruder, twin-screw extruder, Banbury mixer, roll mixer, Brabender Plastograph or kneader.

In this case, it is desirable to select a kneading/granulation method that can achieve good dispersion of each component, and a twin-screw extruder is usually used. During this kneading/granulation, the above-mentioned blend of each component may be kneaded simultaneously, or, in order to improve performance, each component may be divided; for example, first, component (A) and part or all of component (B) may be kneaded, and then the remaining components may be kneaded/granulated.

[III] Molding and Use of Polypropylene Resin Composition (1) Molding Molding of the polypropylene resin composition of the present invention can be carried out by injection molding (including gas injection molding) or injection compression molding (including press injection, hot flow stamping molding, and gas injection compression molding). Among them, the effects of the present invention can be more effectively obtained by injection molding other than gas injection molding and injection compression molding (press injection), and it is preferable to obtain a molded article by such a molding method.
For molding the polypropylene resin composition of the present invention, various molding methods such as blow molding, extrusion molding, compression (press) molding, foam (expansion) molding, sheet molding, thermoforming, stamping molding, powder molding, etc. can be applied as necessary, thereby making it possible to obtain a desired molded product (e.g., an extrusion molded product). Among them, molding methods other than foam (expansion) molding are preferred.

(2) Applications The molded article obtained from the polypropylene resin composition of the present invention has excellent mechanical properties such as density, heat distortion temperature, and impact strength, and has excellent shrinkage anisotropy. The molded article obtained from the polypropylene resin composition of the present invention can be suitably used in applications such as automobile parts, home appliance lighting fixtures, etc.

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

1. Material (1) Component (A)
Novatec PP MA04C (manufactured by Nippon Polo Pro)
Propylene homopolymer produced using a Ziegler catalyst, melt flow rate (MFR, 230°C, 2.16 kg load) 40 g/10 min, melting peak temperature (Tm) = 166°C, density: 0.90 g/cm ³
(2) Component (B)
Wintech PP WMH02 (manufactured by Nippon Polo Pro)
Propene-ethylene random copolymer (ethylene concentration: 0.35% by weight) produced using a metallocene catalyst, melt flow rate (MFR, 230°C, 2.16 kg load) 20g/10min, density: 0.90g/cm ³ , melting peak temperature (Tm) = 152°C
(3) Nucleating agent (C)
(C-1) Adeka STAB NA-11 (ADEKA Corporation)
Sodium 2,2'-methylenebis(4,6-di-t-butylphenyl)phosphate
(C-2) AL-PTBBA (Kyodo Pharmaceutical Co., Ltd.)
Aluminum hydroxydi(p-tert-butylbenzoate)

2. (Examples 1 to 5 and Comparative Examples 1 to 2)
The components were mixed in the ratios shown in Table 1, and kneaded and granulated under the following conditions. The ratio of the nucleating agent in the table is a value shown in parts by weight relative to 100 parts by weight of polyolefin resin. In addition, 0.1 parts by weight of Adeka STAB AO20 manufactured by ADEKA and 0.1 parts by weight of Irgafos 168 manufactured by BASF as a heat stabilizer, and 0.05 parts by weight of Calcium Stearate G manufactured by NOF Corporation as a neutralizing agent were blended per 100 parts by weight of polyolefin resin, and then blended for 3 minutes using Super Floater SFC-50 manufactured by Kawata Co., Ltd., and the strands extruded and kneaded under the following kneading conditions were cut and pelletized. The obtained pellets were injection molded for mechanical properties and shrinkage properties, and the obtained test pieces were evaluated under the following conditions. The evaluation results are shown in Table 1.
Mixing equipment: Kobe Steel KCM50 twin-screw extruder.
Kneading conditions: temperature = 200°C, screw rotation speed = 800 rpm.
(Mechanical property test piece)
Injection molding equipment: Toshiba injection molding machine EC100 and ISO mold type A
Injection molding conditions: primary injection pressure 50 MPa, molding temperature 200°C, mold cooling water temperature 40°C, molding cycle 15 seconds (test piece for shrinkage characteristics)
Injection molding equipment: Toshiba IS100GN and a mold of 100 mm x 100 mm x 2 mm (T) Injection molding conditions: primary injection pressure 70 MPa, molding temperature 240°C, mold cooling water temperature 60°C, molding cycle 50 seconds

3. Evaluation Method (1) Density The density was measured by the underwater displacement method in accordance with JIS-K7112. The unit is g/ ^cm3 .
(2) Heat distortion temperature (HDT)
The measurement was performed in accordance with JIS-K7191-1 at a bending stress of 0.45 MPa.
(3) Impact strength (Charpy impact strength (notched)):
The measurement was performed in accordance with JIS K7111 (notched) at a test temperature of 23° C. (unit: kJ/m ² ).
(4) Shrinkage anisotropy The obtained test pieces were kept (conditioned) for 48 hours in a thermostatic chamber at 23°C and relative humidity (RH) of 50%, and then the shrinkage ratios in the MD and TD directions were measured using a projector (NIKON Corporation, Model No. PROFILE PROJECTOR V-16E). The shrinkage ratios shown in Table 1 were obtained by multiplying the obtained values by ^103. The shrinkage anisotropy was evaluated based on these shrinkage ratios as "shrinkage ratio TD - shrinkage ratio MD".

4. Evaluation From the results shown in Table 1, it can be seen that Examples 1 to 5, which satisfy the requirements for the polypropylene resin composition of the present invention, are excellent in density, heat distortion temperature, and shrinkage anisotropy. As described above, Examples 1 to 5 are judged to be good or to have reached a practical level in all evaluations, and it is clear that the polypropylene resin composition of the present invention can be suitably used in applications such as automobile parts and home appliance lighting fixtures.
On the other hand, Comparative Examples 1 and 2, which do not satisfy the requirements for the polypropylene resin composition of the present invention, have large anisotropy in shrinkage rate and are inferior to Examples 1 to 5.

The polypropylene resin composition of the present invention and a molded article obtained therefrom have reduced density, heat distortion temperature, and shrinkage anisotropy, and therefore can be suitably used in applications such as automobile parts and home appliance lighting fixtures.
can.

Claims (2)

A polypropylene resin composition comprising 85 to 99.5% by weight of a component (A) satisfying the following conditions (A-1) and (A-2), and 0.5 to 15% by weight of a component (B) satisfying the following conditions (B-1) to (B-3), (wherein the total of the components (A) and (B) is 100% by weight) , and 0.01 to 0.25 parts by weight of a nucleating agent (C) per 100 parts by weight of the composition .
Condition (A-1): Component (A) is a propylene homopolymer having a melt flow rate (MFR, 230°C, 2.16 kg load) in the range of 0.5 to 100 g/10 min.
Condition (A-2): Component (A) exhibits a peak melting temperature (Tm) in the range of 160 to 175°C when measured by the DSC method.
Condition (B-1): Component (B) is a propylene-α-olefin random copolymer (wherein the α-olefin is an α-olefin having 2 to 8 carbon atoms (excluding 3 carbon atoms)), and the content of the α-olefin is 0.1 to 5% by weight (wherein the total of the propylene and α-olefin in component (B) is 100% by weight).
Condition (B-2): The melt flow rate (MFR, 230°C, 2.16 kg load) of component (B) is in the range of 0.5 to 100 g/10 min.
Condition (B-3): Component (B) exhibits a peak melting temperature (Tm) in the range of 110°C or higher and lower than 160°C when measured by a DSC method. A molded article obtained from the polypropylene resin composition according to claim 1 .