WO2017164343A1

WO2017164343A1 - Polypropylene resin composition for injection foam molding and injection foam molded body of same

Info

Publication number: WO2017164343A1
Application number: PCT/JP2017/011863
Authority: WO
Inventors: 総一郎辻本; 正樹天野; 金田　豊
Original assignee: 株式会社カネカ
Priority date: 2016-03-24
Filing date: 2017-03-23
Publication date: 2017-09-28
Also published as: JPWO2017164343A1

Abstract

Provided is a polypropylene resin composition which is capable of providing an injection foam molded body that has excellent impact resistance and good foam state. This composition contains a conjugated diene-modified polypropylene resin (A) which is a conjugated diene-modified propylene-ethylene block copolymer having a melt flow rate of 1 g/10 min or more but less than 80 g/10 min and a polypropylene resin (B) which is a propylene-ethylene block copolymer having a melt flow rate of 1 g/10 min or more but less than 80 g/10 min. This composition is configured such that: the content of the ethylene component in the component (A) is 1% by weight or more; the content of the component (A) is 1-49% by weight and the content of the component (B) is 51-99% by weight relative to 100% by weight of the total of the component (A) and the component (B); and the melt tension of the composition is 0.1 gf or more but less than 2.0 gf.

Description

Polypropylene resin composition for injection foam molding and injection foam molded body thereof

The present invention relates to a polypropylene resin composition that can be suitably used for injection foam molding, and an injection foam molded body thereof.

Polypropylene resin has good physical properties and moldability, and its use range is rapidly expanding as an environmentally friendly material. In particular, for automobile parts and the like, lightweight and excellent polypropylene resin products are provided. One such product is a polypropylene resin injection foam molding.

Generally, as a characteristic of a polypropylene resin used for injection foam molding, fluidity for filling the resin into every corner of the mold and foamability for foaming thereafter are required.

However, the linear polypropylene resin usually used has a low impact resistance, so that the foam is easily broken, and it is difficult to apply it to uses in which the impact resistance is important. Moreover, there existed a tendency for the foaming defect to be easy to generate | occur | produce judged that a cell state is inferior by visual observation.

For example, the following proposals have been made for these improvements.

In Patent Document 1, a composition comprising (A) a linear polypropylene resin, (B) a modified polypropylene resin exhibiting strain-hardening properties, and a foaming agent is injected into a mold by injection foam molding. And a molded article obtained by the method are disclosed, and it is described that a high expansion ratio is possible and the surface appearance is good. However, only the polypropylene homopolymer was used as the base resin for modifying the component (B), and the impact resistance was insufficiently improved.

Patent Document 2 discloses a method for producing (A) a modified polypropylene resin obtained by melt-kneading (a) a polypropylene resin, (b) an isoprene monomer, and (c) a radical polymerization initiator. It is described that the obtained (A) exhibits strain-hardening properties and may be used for foam molding. However, there is no description about injection foam molding, and in that case, there is no description or suggestion about the impact resistance and the cell state when foamed, so it is not easy to apply to injection foam molding, The effect when applied was also completely unknown. In addition, there is no description that the component (A) is used in combination with an unmodified polypropylene resin.

In Patent Document 3, (a) a polypropylene resin, (b) an isoprene monomer, and (c) a radical polymerization initiator obtained by melt-kneading, (A) a modified polypropylene resin is foamed. The manufacturing method of a body is disclosed, and it is described that the heat-resistant and the foaming molding which was excellent in the expansion ratio is obtained. However, there is no description about injection foam molding, and in that case, there is no description or suggestion about the impact resistance and the cell state when foamed, so it is not easy to apply to injection foam molding, The effect when applied was also completely unknown. In addition, there is no description that the component (A) is used in combination with an unmodified polypropylene resin.

In Patent Document 4, (a) a modified polypropylene resin obtained by melt kneading (a) a polypropylene resin, (b) a monomer such as isoprene, and (c) a radical polymerization initiator is foamed. The foamed sheet obtained is disclosed, and it is described that the drawdown during heating is small and the closed cell ratio is excellent. However, there is no description about injection foam molding, and there is no description or suggestion about the impact resistance and the cell state when foamed, so it is not easy to apply to injection foam molding, and when applied The effect was also completely unknown. In addition, there is no description that the component (A) is used in combination with an unmodified polypropylene resin.

Patent Document 5 discloses a method of injection-molding a composition containing (A) a modified polypropylene resin exhibiting strain hardening and (C) a foaming agent into a mold, and a molding obtained thereby. The body is disclosed, and it is described that the foam moldability is good and the rigidity is excellent. Although propylene-ethylene block copolymer is used as the base resin for modification, there is no description or suggestion about impact resistance, so the effect when applied to applications that place importance on impact resistance is completely unknown. It was. In addition, there is no description that the component (A) is used in combination with an unmodified polypropylene resin.

As described above, in a polypropylene resin composition for injection foam molding, it has been difficult to obtain a polypropylene resin composition that achieves both impact resistance and a cell state when foamed.

JP 2005-224963 A JP 09-188729 A JP 09-188774 A JP 2001-139716 A JP 2007-130992 A

An object of the present invention is to provide a polypropylene-based resin composition that is excellent in impact resistance and can provide an injection foam molded article having a good foamed state, and an injection foam molded article thereof.

The present invention is as follows.

[1] A conjugated diene-modified polypropylene resin, which is a conjugated diene-modified propylene-ethylene block copolymer, having a melt flow rate measured at 230 ° C. and a load of 2.16 kg of 1 g / 10 min or more and less than 80 g / 10 min. (A) and
Polypropylene for injection foam molding containing a polypropylene resin (B) which is a propylene-ethylene block copolymer having a melt flow rate measured at 230 ° C. and a load of 2.16 kg of 1 g / 10 min or more and less than 80 g / 10 min. A resin composition comprising:
The content of the ethylene component in the component (A) is 1% by weight or more,
The content of the component (A) is 1 to 49% by weight and the content of the component (B) is 51 to 99% by weight with respect to the total of 100% by weight of the component (A) and the component (B).
A polypropylene resin composition for injection foam molding, wherein a melt tension measured at 200 ° C. and 10 m / min of the composition is 0.1 gf or more and less than 2.0 gf.

[2] The composition is a polypropylene resin for injection foam molding according to [1], wherein a melt flow rate measured at 230 ° C. and a load of 2.16 kg is 8 g / 10 min or more and less than 80 g / 10 min. Composition.

[3] The content of the component (A) is 1 to 25% by weight, the content of the component (B) is 75 to 99% by weight with respect to the total of 100% by weight of the component (A) and the component (B), and ,
The polypropylene system for injection foam molding according to the above [1] or [2], wherein the melt flow rate of the component (A) measured at 230 ° C. and a load of 2.16 kg is 20 g / 10 min or more and less than 80 g / 10 min. Resin composition.

[4] The content of the component (A) is 1 to 25% by weight, the content of the component (B) is 75 to 99% by weight with respect to the total of 100% by weight of the component (A) and the component (B), and ,
The polypropylene system for injection foam molding according to the above [1] or [2], wherein the melt flow rate measured at 230 ° C. under a 2.16 kg load of the component (A) is 1 g / 10 min or more and less than 20 g / 10 min. Resin composition.

[5] An injection-foamed molded article of the polypropylene resin composition according to any one of [1] to [4].

The polypropylene resin composition of the present invention is excellent in impact resistance and can give an injection foam molded article having a good foamed state. Therefore, the polypropylene resin composition of the present invention can be suitably used for injection foam molded articles such as automobile interior materials.

Graph in which melt tension is plotted against MFR obtained in each example and comparative example

Hereinafter, embodiments of the present invention will be described.

The present invention relates to a polypropylene resin composition for injection foam molding. The composition is a conjugated diene-modified polypropylene which is a conjugated diene-modified propylene-ethylene block copolymer having a melt flow rate measured at 230 ° C. and a load of 2.16 kg of 1 g / 10 min or more and less than 80 g / 10 min. And a polypropylene resin (B) which is a propylene-ethylene block copolymer having a melt flow rate measured at 230 ° C. and a load of 2.16 kg of 1 g / 10 min or more and less than 80 g / 10 min Containing. The content of the ethylene component in the component (A) is 1% by weight or more, and the content of the component (A) is 1 to 49% by weight with respect to the total of 100% by weight of the component (A) and the component (B). ) The component content is 51 to 99% by weight, and the melt tension of the composition measured at 200 ° C. and 10 m / min is 0.1 gf or more and less than 2.0 gf.

<Conjugated Diene Modified Polypropylene Resin (A)>
The conjugated diene modified polypropylene resin (A) of the present invention is a conjugated diene modified propylene having a melt flow rate of 1 g / 10 min or more and less than 80 g / 10 min measured at 230 ° C. and a load of 2.16 kg. An ethylene block copolymer.

When the melt flow rate of the component (A) is less than 1 g / 10 min, the resin composition is insufficient in fluidity, resulting in molding defects such as short shots and deterioration of mold transferability in injection foam molding with a large mold. May cause surface defects. When the melt flow rate of the component (A) is 80 g / 10 min or more, mixing with the component (B) may be insufficient, or the impact resistance of the injection foamed molded product may be insufficient. The component (A) melt flow rate is preferably 20 g / 10 min or more and less than 80 g / 10 min when emphasizing the mold transfer property and the surface property of the molded body, and when the impact resistance of the molded body is important. Is preferably 1 g / 10 min or more and less than 20 g / 10 min.

Here, the melt flow rate (hereinafter sometimes abbreviated as “MFR”) is 230 ° C. using a melt indexer F-F01 (manufactured by Toyo Seiki Seisakusho Co., Ltd.) in accordance with JIS K7210: 1999. 2. A value obtained by converting the amount of resin extruded from a die in a certain time under a load of 16.16 kg into the amount of resin extruded in 10 minutes. This converted value was calculated by MFR automatic calculation processing (B method). The calculation formula is as follows. This method was applied even when the melt flow rate exceeded 50 g / 10 min.

MFR (g / 10 minutes) = (427 × Lxρ) / t
L (test condition interval): 3 (cm)
ρ (melt density at the test temperature): a value (g / cm ³ ) calculated by the following formula by the cutting method, but 0.75 (g / cm ³ ) when the cutting method is impossible ρ = M / (0.711xL)
m: Mass of the sample (g) measured by the cut-off method and moved out of the interval L by the piston
L: Same as the above interval t (interval movement time): Actual measured value (seconds)
That is, when the cutting method can be applied, it may be calculated by the following calculation formula.

MFR (g / 10 min) = (600 × m) / t
The conjugated diene modified polypropylene resin (A) of the present invention has a melt tension measured at 200 ° C. and 10 m / min, preferably 1.0 gf or more, more preferably 2.0 gf or more. When the melt tension of the component (A) is 1.0 gf or more, it becomes easy to obtain an injection foam molded article having uniform fine bubbles, for example, at a foaming ratio of 2 or more.

When the MFR of the resin composition is X, the melt tension Y of the resin composition is preferably not more than the melt tension obtained from the following linear equation from the viewpoint of impact resistance.
Y ≦ (−0.032) X + 1.91
(Y is the melt tension (gf) of the resin composition, and X is the MFR (g / 10 minutes) of the resin composition)
The conjugated diene modified polypropylene resin (A) of the present invention is a conjugated diene modified propylene-ethylene block copolymer. The copolymer is a resin obtained by reacting a propylene-ethylene block copolymer with a conjugated diene compound to introduce a branched structure into the propylene-ethylene block copolymer and increasing the molecular weight thereof. The copolymer is preferably obtained by melt-mixing a propylene-ethylene block copolymer (a), a radical polymerization initiator (b) and a conjugated diene compound (c). This molten mixture is excellent in that it does not require expensive equipment and can be produced at low cost.

<Propylene-ethylene block copolymer (a)>
The propylene-ethylene block copolymer (a) used for obtaining the conjugated diene-modified polypropylene-based resin (A) includes a polymer mainly composed of ethylene in a linear polymer mainly composed of propylene, and A propylene-based polymer in which an ethylene-propylene-rubbery copolymer is dispersed to form a sea-island structure. Such a propylene-based polymer is called impact-resistant polypropylene, and conventionally called block polypropylene in Japan, but is not a block copolymer in a chemical sense. In the present invention, the propylene-ethylene block copolymer (a) is a propylene homopolymer or a copolymer (a1) mainly composed of propylene, an ethylene homopolymer (a2) and / or ethylene and carbon number. A mixture containing a copolymer (a3) with 3 to 10 α-olefin is preferable. At this time, (a1) corresponds to a linear polymer mainly composed of propylene which is a matrix, (a2) corresponds to a polymer mainly composed of ethylene, and (a3) corresponds to an ethylene-propylene rubber-like copolymer. Corresponds to coalescence.

The propylene-ethylene block copolymer (a) is preferably a copolymer containing 51% by weight or more of a propylene component. From the viewpoint of crystallinity, rigidity, chemical resistance, etc., the propylene component is 60% by weight or more. The contained copolymer is more preferable, 70% by weight or more is further preferable, and 80% by weight or more is particularly preferable.

The propylene-ethylene block copolymer (a) contains 1% by weight or more of an ethylene component from the viewpoint of impact resistance, etc., but preferably contains 3% by weight or more. Is more preferable, 8% by weight or more is further preferable, and 10% by weight or more is particularly preferable.

The propylene-ethylene block copolymer (a) may be a copolymer obtained by copolymerizing a monomer copolymerizable with propylene in addition to propylene and ethylene. Examples of such monomers copolymerizable with propylene include 1-butene, isobutene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, and 3,4-dimethyl. 4 to 12 α-olefins such as 1-butene, 1-heptene, 3-methyl-1-hexene, 1-octene, 1-decene; cyclopentene, norbornene, tetracyclo [6,2,11,8,13, 6] Cyclic olefins such as 4-dodecene; 5-methylene-2-norbornene, 5-ethylidene-2-norbornene, 1,4-hexadiene, methyl-1,4-hexadiene, 7-methyl-1,6-octadiene Diene such as vinyl chloride, vinylidene chloride, acrylonitrile, vinyl acetate, acrylic acid, methacrylic acid, maleic acid, acrylic acid Chill, butyl acrylate, methyl methacrylate, maleic anhydride, styrene, methyl styrene, vinyl toluene, vinyl monomers such as divinylbenzene; and the like. These may be used alone or in combination of two or more. Of these, α-olefins are preferable and 1-butene is more preferable in terms of improving cold resistance and low cost.

Examples of commercially available propylene-ethylene block copolymers (a) include J709UG (MFR = 55), J708UG (MFR = 45), J830HV (MFR = 30), J717ZG (MFR = 32), J707EG (MFR = 30), J707G (MFR = 30), J715M (MFR = 9), J705UG (MFR = 9), J704UG (MFR = 5), J702LB (MFR = 1.8), and the like. . For example, according to International Publication No. 2015/060201, J708UG has an ethylene polymer content of 14% by mass and can be suitably used in the present invention.

<Radical polymerization initiator (b)>
The radical polymerization initiator (b) used to obtain the conjugated diene-modified polypropylene resin (A) generally includes peroxides and azo compounds, but the propylene-ethylene block copolymer (a) and Those having hydrogen abstraction ability from the conjugated diene compound (c) are preferred. Although it does not specifically limit, For example, organic peroxides, such as a ketone peroxide, a peroxy ketal, a hydroperoxide, a dialkyl peroxide, a diacyl peroxide, a peroxy dicarbonate, a peroxy ester, are mentioned.

Among these, those having particularly high hydrogen abstraction ability are preferable, for example, 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane. N-butyl 4,4-bis (t-butylperoxy) valerate, peroxyketals such as 2,2-bis (t-butylperoxy) butane, dicumyl peroxide, 2,5-dimethyl-2, 5-di (t-butylperoxy) hexane, α, α'-bis (t-butylperoxy-m-isopropyl) benzene, t-butylcumyl peroxide, di-t-butylperoxide, 2,5- Diacyl peroxide such as dimethyl-2,5-di (t-butylperoxy) -3-hexyne and benzoyl peroxide -Oxide, t-butyl peroxyoctate, t-butyl peroxyisobutyrate, t-butyl peroxylaurate, t-butyl peroxy 3,5,5-trimethylhexanoate, t-butyl peroxyisopropyl carbonate Peroxyesters such as 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-butylperoxyacetate, t-butylperoxybenzoate, and di-t-butylperoxyisophthalate It is done. These may be used alone or in combination of two or more.

The addition amount of the radical polymerization initiator (b) used for obtaining the conjugated diene-modified polypropylene resin (A) is 0.05% by weight with respect to 100 parts by weight of the propylene-ethylene block copolymer (a). Part to 10 parts by weight, preferably 0.2 part to 5 parts by weight. If the addition amount of the radical polymerization initiator is less than 0.05 parts by weight, the modification may be insufficient. If the amount exceeds 10 parts by weight, the molecular chain scission takes priority over the modification, and the desired modification is achieved. Quality effects may not be obtained.

<Conjugated diene compound (c)>
Examples of the conjugated diene compound (c) used to obtain the conjugated diene-modified polypropylene resin (A) include butadiene, isoprene, 1,3-heptadiene, 2,3-dimethylbutadiene, 2,5-dimethyl- 2,4-hexadiene and the like can be mentioned. These may be used alone or in combination. Of these, butadiene and isoprene are preferred because they are inexpensive and easy to handle and the reaction easily proceeds uniformly.

The addition amount of the conjugated diene compound (c) is preferably 0.01 parts by weight or more and 5 parts by weight or less, and 0.05 parts by weight or more and 2 parts by weight with respect to 100 parts by weight of the propylene-ethylene block copolymer (a). Part or less is more preferable. If the addition amount of the conjugated diene compound is less than 0.01 parts by weight, the modification may be insufficient, and if it exceeds 5 parts by weight, the fluidity may be insufficient.

In producing the conjugated diene-modified polypropylene resin (A), a monomer copolymerizable with the conjugated diene compound may be used in combination with the conjugated diene compound. Examples of such copolymerizable monomers include vinyl chloride, vinylidene chloride, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, vinyl acetate, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, acrylic acid. Metal salt, metal methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, and other acrylic esters, methyl methacrylate, ethyl methacrylate, butyl methacrylate, methacrylic acid 2 -Methacrylic acid esters such as ethylhexyl and stearyl methacrylate.

<Conditions for production of conjugated diene-modified polypropylene resin (A)>
When the conjugated diene-modified polypropylene resin (A) is produced, the radical polymerization initiator (b) is added in an amount of 0.1 to 10 times the weight of the conjugated diene compound (c). (Standard), the melt flow rate of the conjugated diene-modified polypropylene resin (A) can be adjusted relatively easily to a range of 1 or more and less than 80. The addition amount of the radical polymerization initiator (b) is preferably 0.5 to 7.5 times the addition amount of the conjugated diene compound (c), more preferably 0.75 to 5 times. It is.

In order to obtain the conjugated diene-modified polypropylene resin (A), an apparatus for reacting the propylene-ethylene block copolymer (a), the radical polymerization initiator (b), and the conjugated diene compound (c) includes: Rollers, kneaders, Banbury mixers, Brabenders, single-screw extruders, twin-screw extruders and other kneading machines, twin-screw surface renewal machines, horizontal twin-disk devices such as double-shaft multi-disk devices, and vertical helical ribbon stirrers Mold stirrer and the like. Among these, a kneader is preferably used, and an extruder is particularly preferable from the viewpoint of productivity.

The order of mixing and kneading (stirring) the propylene-ethylene block copolymer (a), the radical polymerization initiator (b), and the conjugated diene compound (c) to obtain the conjugated diene-modified polypropylene resin (A). There is no particular limitation on the method. The propylene-ethylene block copolymer (a), the radical polymerization initiator (b), and the conjugated diene compound (c) may be mixed and then melt-kneaded (stirred), or the propylene-ethylene block copolymer (a ) And then kneading (stirring), the radical polymerization initiator (b) and the conjugated diene compound (c) may be mixed simultaneously or separately, collectively or dividedly. The temperature of the kneading (stirring) machine is preferably 130 to 300 ° C. from the viewpoint that the propylene-ethylene block copolymer (a) melts and does not thermally decompose. The kneading (stirring) time is generally preferably 1 to 60 minutes.

As described above, the conjugated diene-modified polypropylene resin (A) can be produced. There is no restriction | limiting in the shape and magnitude | size of the conjugated diene modified polypropylene resin (A) manufactured, A pellet form may be sufficient.

<Polypropylene resin (B)>
The polypropylene resin (B) of the present invention is a propylene-ethylene block copolymer having a melt flow rate of 1 g / 10 min or more and less than 80 g / 10 min measured under conditions of 230 ° C. and 2.16 kg load. . However, the propylene-ethylene block copolymer modified with conjugated diene is not included in the category of the polypropylene resin (B).

When the melt flow rate of the component (B) is less than 1 g / 10 min, when producing an injection molded body, if the mold cavity has a thin part with a clearance of, for example, about 1 to 2 mm, it melts at a relatively low pressure. It may be difficult to fill the resin into the mold, and it may not be possible to carry out continuous and stable injection molding. When the melt flow rate of the component (B) is 80 g / 10 min or more, the fluidity is excessive and the injection molding tends to become unstable. The melt flow rate of the component (B) is more preferably 3 g / 10 min or more and 70 g / 10 min or less, and further preferably 5 g / 10 min or more and less than 70 g / 10 min. The measurement conditions for the melt flow rate are the same as those described above.

The polypropylene resin (B) of the present invention is a propylene-ethylene block copolymer. A propylene-ethylene block copolymer is a linear polymer mainly composed of propylene, in which a polymer mainly composed of ethylene and an ethylene-propylene rubber-like copolymer are dispersed to form a sea-island structure. Specifically, the same propylene-ethylene block copolymer (a) as described above can be used.

<Polypropylene resin composition for injection foam molding>
The polypropylene resin composition for injection foam molding of the present invention is excellent in impact resistance and good by using a combination of the conjugated diene-modified polypropylene resin (A) and the polypropylene resin (B) described above. An injection foam molded article having a foamed state can be provided. In order to obtain such an injection-molded body, both components are blended so that the content of the component (B) is larger than the content of the component (A). Specifically, the content of the component (A) is 1 to 49% by weight and the content of the component (B) is 51 to 99% by weight with respect to the total of 100% by weight of the component (A) and the component (B). . In this range, it is possible to obtain an injection foam molded article having excellent impact resistance and a good foamed state. From the viewpoint of impact resistance, the content of component (A) is preferably 1 to 25% by weight, more preferably 5 to 25% by weight, and still more preferably 10 to 20% by weight.

Also, the suitable range of the MFR and content of the component (A) can vary depending on the MFR of the component (B). For example, when the MFR of the component (B) is less than 8 g / 10 minutes, the MFR of the component (A) is preferably 20 g / 10 minutes or more, more preferably 40 g / 10 minutes or more from the viewpoint of fluidity, When the MFR of the component (A) is less than 20 g / 10 minutes, problems such as deterioration of mold transferability may occur due to insufficient fluidity. When the MFR of the component (B) is less than 8 g / 10 minutes as described above, the amount of the component (A) added is preferably 5 to 49% by weight, more preferably 10 to 35% by weight.

The polypropylene resin composition for injection foam molding of the present invention has a melt tension measured at 200 ° C. and 10 m / min of 0.1 gf or more and less than 2.0 gf. When the melt tension of the polypropylene resin composition is within the above range, an injection foam molded article having excellent impact resistance and a good foamed state can be obtained. The melt tension of the resin composition is a numerical value measured after sufficiently melting and kneading each component, and the melt flow rate indicated by each of the conjugated diene-modified polypropylene resin (A) and the polypropylene resin (B), It can be easily adjusted depending on the kind, combination, blending amount, and the like of the components.

The melt tension represents the tension required to deform the molten resin, whereas the melt flow rate is a measure showing the fluidity of the molten resin, so they are different concepts.

The melt flow rate of the polypropylene resin composition for injection foam molding of the present invention is not limited, but is preferably 8 g / 10 min or more and less than 80 g / 10 min. This melt flow rate is measured under the conditions described above. When the melt flow rate of the polypropylene resin composition is within this range, the polypropylene resin composition for injection foam molding has fluidity suitable for injection foam molding and has high impact resistance after injection foam molding. A molded body can be obtained.

The melt flow rate of the polypropylene resin composition is a numerical value measured after sufficiently melting and kneading each component, and the melt flow rate indicated by each of the conjugated diene-modified polypropylene resin (A) and the polypropylene resin (B). And it can be easily adjusted depending on the blending amount of each component.

<Foaming agent (C)>
The polypropylene resin composition for injection foam molding of the present invention contains a foaming agent. The foaming agent that can be used in the present invention can be used without particular limitation as long as it can be usually used for injection foam molding, and may be either a chemical foaming agent or a physical foaming agent.

The chemical foaming agent is mixed with a resin component in advance and then supplied to an extruder or an injection molding machine, and decomposes in a cylinder to generate a gas such as carbon dioxide. The chemical foaming agent is not particularly limited, and examples thereof include inorganic chemical foaming agents such as sodium bicarbonate and ammonium carbonate, and organic chemical foaming agents such as azodicarbonamide and N, N′-dinitrosopentamethylenetetramine. It is done. These may be used alone or in combination of two or more.

The physical foaming agent is injected as a gaseous or supercritical fluid into the molten resin in the cylinder of an extruder or injection molding machine, and is dispersed or dissolved. After injection into the mold, the pressure is released. It functions as a foaming agent. The physical foaming agent is not particularly limited, but examples thereof include aliphatic hydrocarbons such as propane and butane, alicyclic hydrocarbons such as cyclobutane and cyclopentane, halogenated hydrocarbons such as chlorodifluoromethane and dichloromethane, nitrogen, and the like. And inorganic gases such as carbon dioxide and air. These may be used alone or in combination of two or more.

Among these foaming agents, it can be safely used in ordinary extruders and injection molding machines, and it is easy to obtain uniform fine bubbles. As chemical foaming agents, inorganic chemical foaming agents, and as physical foaming agents, nitrogen Inorganic gases such as carbon dioxide and air are preferred. These foaming agents include, for example, foaming aids such as organic acids such as citric acid, talc, lithium carbonate, etc. A nucleating agent such as inorganic fine particles may be added. Usually, the inorganic chemical foaming agent is prepared from a polyolefin resin master batch having a concentration of the foaming agent of 10 to 75% by weight from the viewpoints of handleability, storage stability, and dispersibility in polypropylene resin. Are preferably used.

The amount of the foaming agent used in the present invention can be appropriately set depending on the foaming ratio of the final product, the type of foaming agent, and the resin temperature during molding. For example, the inorganic chemical foaming agent is preferably in the range of 0.5 to 30 parts by weight, more preferably 1 to 20 parts by weight, with respect to 100 parts by weight of the polypropylene resin composition of the present invention. Used in. By using the inorganic chemical foaming agent in this range, it is possible to economically and easily obtain an injection foam molded article having a foaming ratio of 2 times or more and uniform fine cells. On the other hand, the physical foaming agent is preferably injected in an amount of 0.05 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, with respect to 100 parts by weight of the polypropylene resin composition. Used by supplying to a molding machine.

<Other additives>
The polypropylene-based resin composition of the present invention is a high-density polyethylene-based resin as well as a polypropylene resin that does not fall under any of the components (A) and (B) as long as the effects of the present invention are not impaired. Resin, high-pressure low-density polyethylene resin, linear low-density polyethylene resin, ethylene-α-olefin copolymer, olefin-based elastomer, styrene-based elastomer, and other thermoplastic resins .

In addition, the polypropylene resin composition of the present invention is an antioxidant, a metal deactivator, a phosphorus processing stabilizer, an ultraviolet absorber, an ultraviolet stabilizer, as long as the effects of the present invention are not impaired, if necessary. Stabilizers such as fluorescent brighteners, metal soaps, antacid adsorbents, crosslinking agents, chain transfer agents, nucleating agents, plasticizers, lubricants, fillers, reinforcing materials, pigments, dyes, flame retardants, antistatic agents, etc. These additives may be further contained.

<Injection foam molding>
The present invention also relates to an injection-foamed molded article of the polypropylene resin composition.

The expansion ratio of the injection-foamed molded article of the present invention is preferably 1.5 to 10 times, more preferably 2 to 6 times. If the expansion ratio is less than 1.5 times, it tends to be difficult to obtain light weight, and if it exceeds 10 times, the rigidity tends to be significantly reduced.

<Injection foam molding method>
It does not specifically limit as an injection foam molding method which can be used in order to manufacture the injection foam molding of this invention, A well-known method is applicable. Specific molding conditions at that time can be appropriately determined in consideration of the melt flow rate, melt tension, type of molding machine, mold shape, and the like of the polypropylene resin composition. As an example, the resin temperature is preferably 170 to 300 ° C., more preferably 190 to 270 ° C., and the mold temperature is preferably 10 to 100 ° C., more preferably 20 to 80 ° C. Further, it is preferable to carry out under conditions such as a molding cycle of 1 to 120 minutes, an injection speed of 10 to 300 mm / second, and an injection pressure of 10 to 200 MPa.

Hereinafter, the present invention will be described in more detail by way of examples. However, the present invention is not limited to these examples.

In the examples and comparative examples, the test methods and criteria used for various evaluation methods are as follows.

(1) Melt flow rate (MFR)
In accordance with JIS K7210: 1999, the amount of resin extruded from a die at a predetermined time under a condition of 230 ° C. and 2.16 kg load using a melt indexer F-F01 (manufactured by Toyo Seiki Seisakusho) is 10 The value converted into the amount of resin extruded per minute was taken as the melt flow rate. This converted value was calculated by MFR automatic calculation processing (B method). The calculation formula is as follows. This method was applied even when the melt flow rate exceeded 50 (g / 10 min).

MFR (g / 10 minutes) = (427 × Lxρ) / t
L (test condition interval): 3 (cm)
ρ (melt density at test temperature): a value calculated by the following formula by the cutting method, but when the cutting method is not possible, 0.75 (g / cm 3) ρ = m / (0.711 × L )
m: Mass of the sample (g) measured by the cut-off method and moved out of the interval L by the piston
L: Same as the above interval t (interval movement time): Actual measured value (seconds)
That is, when the cutting method can be applied, it may be calculated by the following calculation formula.

MFR (g / 10 min) = (600 × m) / t
(2) Melt tension (MT)
A capillograph (manufactured by Toyo Seiki Seisakusyo Co., Ltd.) equipped with a melt tension measurement attachment and having a φ10 mm cylinder fitted with an orifice of φ1 mm and a length of 10 mm at the tip was used. The sample was filled in a cylinder heated to 200 ° C. and preheated for 5 minutes. After the preheating time has elapsed, when the piston descends at a rate of 10 mm / min, the strand discharged from the die is placed on a pulley with a load cell below 370 mm or 520 mm and pulled at a speed of 10 m / min. The load applied to was measured over time. About 5 minutes after the start of the measurement, the maximum value and the minimum value of the load obtained after the blurring of the load was substantially stabilized were measured, and the average value thereof was taken as the melt tension. The melt tension was set to 0 when the load applied to the pulley with the load cell was so low that it could not be detected.

Also, when the strand breaks when measuring the melt tension under the above conditions, the melt tension at 10 m / min is too high, so the melt tension was measured by changing the take-up speed to 3 m / min. In principle, when the value measured at 10 m / min is compared with the value measured at 3 m / min, the former is higher and the latter is lower. Therefore, when the fracture occurs under the former conditions, it is higher than the latter value. Can be estimated.

(3) DuPont impact test Using a DuPont impact tester (manufactured by Yasuda Seiki Seisakusho), the 50% fracture height was determined by the steer case method using constant drop weight, and the energy value was calculated from the load at that time. The drop load was 300 g, 700 g, or 1000 g, and the energy value was calculated according to JIS-K-7221.

(4) Visual Evaluation of Cell State of Foam Using an injection molding machine (MD350S-IV manufactured by Niigata Machine Techno), the resin composition is completely filled in the following evaluation mold under the following molding conditions. Injection molded with minimum filling pressure.
・ Resin temperature: 200 ℃
・ Mold temperature: 40 ℃
・ Injection speed: 100mm / sec
-Mold used: Flat plate mold with 1-point pin gate at the bottom center In collecting the molded product, 4 shots after purging (material switching) were discarded and 7 subsequent shots were collected in order to guarantee the stability of the injection state. The injection molded body was cut, and the foamed state of the cross section was visually observed. The foaming state was evaluated according to the following criteria.
A: The test sample has the best foamability. B: The test sample has the best foamability. Δ: The test sample has the poor foamability. (5) DSC measurement JIS K7122 ( 1987), using a differential scanning calorimeter DSC6200 manufactured by Seiko Instruments Inc., 4 to 10 mg of a measurement sample was heated from 30 ° C. to 210 ° C. at a rate of 10 ° C./min and once melted. (1st scan), after the heat history of cooling from 210 ° C. to 30 ° C. at a rate of 10 ° C./min. A DSC curve of (2nd scan) was obtained. In the obtained DSC curve, a base line is drawn so as to extend a portion that can be regarded as a substantially straight line on both sides across the peak of the DSC curve, and the DSC curve is separated from the low temperature side baseline a and the high temperature side baseline. The amount of heat of fusion calculated from the area of the portion surrounded by the line ab connecting the point b and the DSC curve was ΔH. On the other hand, in the obtained DSC curve, the temperature at the point where the endothermic amount becomes maximum at one melting peak was defined as the melting peak temperature. When there were two or more melting peaks, the maximum endothermic temperature at each peak was defined as the respective peak temperature, and it was clearly shown that there were two peak temperatures.

In the examples, 2nd scan values are shown.

<Preparation of conjugated diene modified polypropylene resin>
(Production Example 1)
(A) 100 parts by weight of a propylene-ethylene block copolymer (a-1) (containing 14% by weight of an ethylene component) as a propylene-ethylene block copolymer and a melt flow rate of 45 g / 10 min, and (b) a radical A mixture of 1.1 parts by weight of t-butylperoxyisopropyl carbonate as a polymerization initiator was supplied from a hopper to a 46 mmφ twin screw extruder (L / D = 40) at 70 kg / hour, and melt kneaded at a cylinder temperature of 200 ° C. Then, from the press-fitting portion provided in the middle, (c) 0.32 parts by weight (0.245 kg / hour) of isoprene monomer as a conjugated diene compound was supplied using a metering pump in the twin-screw extruder. Was then kneaded to obtain pellets of the conjugated diene-modified polypropylene resin (A-1). MFR = 60 g / 10 min. The obtained conjugated diene-modified polypropylene resin (A-1) is shown in Table 1.

(Production Example 2)
(B) Production Example 1 except that the amount of t-butylperoxyisopropyl carbonate as a radical polymerization initiator was changed to 1.1 parts by weight, and the amount of isoprene supplied as a (c) conjugated diene compound was changed to 0.41 parts by weight. In the same manner as above, a conjugated diene-modified polypropylene resin (A-2) was obtained. MFR = 40 g / 10 min.

(Production Example 3)
(A) A polypropylene homopolymer (a-2) having a melt flow rate of 45 g / 10 min was used in place of the propylene-ethylene block copolymer, and (b) t-butylperoxyisopropyl carbonate as a radical polymerization initiator was used. The conjugated diene modified polypropylene resin (A-3) was prepared in the same manner as in Production Example 1, except that the amount was 1.1 parts by weight and (c) the amount of isoprene supplied as the conjugated diene compound was changed to 0.4 parts by weight. ) MFR = 60 g / 10 min.

(Production Example 4)
(B) Production Example 3 except that the amount of t-butylperoxyisopropyl carbonate as a radical polymerization initiator was changed to 1.1 parts by weight, and the amount of isoprene supplied as a (c) conjugated diene compound was changed to 0.44 parts by weight. In the same manner as above, a conjugated diene-modified polypropylene resin (A-4) was obtained. MFR = 40 g / 10 min.

(Production Example 5)
(A) A polypropylene homopolymer (a-3) having a melt flow rate of 8 g / 10 min was used in place of the propylene-ethylene block copolymer, and (b) t-butyl peroxyisopropyl carbonate was used as a radical polymerization initiator. Conjugated diene modified polypropylene resin (A-5) in the same manner as in Production Example 3, except that the amount was changed to 0.75 parts by weight and (c) the amount of isoprene supplied as the conjugated diene compound was changed to 0.5 parts by weight. ) MFR = 7 g / 10 min.

(Production Example 6)
(A) 100 parts by weight of a propylene-ethylene block copolymer (a-4) (containing 14% by weight of an ethylene component) having a melt flow rate of 5 g / 10 min as a propylene-ethylene block copolymer, (b) Except for changing the amount of t-butyl peroxyisopropyl carbonate as a radical polymerization initiator to 1.1 parts by weight and (c) the supply amount of isoprene as a conjugated diene compound to 0.42 parts by weight, the same as in Production Example 1. As a result, a conjugated diene-modified polypropylene resin (A-6) was obtained. MFR = 9 g / 10 min.

<Polypropylene resin>
Table 2 shows the resins used as the polypropylene resin (B).

(Examples 1 to 11)
<Preparation of polypropylene resin composition>
Dry blending with conjugated diene modified polypropylene resin (A), polypropylene resin (B), foaming agent (C), and color masterbatch as colorant (D) at the types and composition ratios shown in Table 3. The sample was subjected to injection foam molding.

As (C), 3 parts by weight of EE25C (manufactured by Eiwa Kasei), and as (D), 1.5 parts by weight of DAICOLOR PP-M77255 (black) manufactured by Dainichi Seika Co., Ltd. (B) was used as 100 parts by weight).

<Foaming evaluation of injection foam molding>
The above injection foam molding was evaluated according to the items of foaming evaluation described above.

(Comparative Examples 1 to 19)
Dry blending, injection foam molding, and evaluation were carried out in the same manner as in Example 1 with the types and composition ratios shown in Table 4.
The obtained results are shown in Tables 3 and 4.

(4a) When component (A) is a modified propylene-ethylene block copolymer, and component (B) is a propylene-ethylene block copolymer: Examples 1 to 3 and Comparative Example 1 are both modified propylene- It contains an ethylene block copolymer (A-2) and a propylene-ethylene block copolymer (B-1). The blending amount of (A-2) is 1 to 49% by weight (provided that the component (A) and It can be seen that the Dupont impact strength of the foam can be increased by setting the total amount of the component (B) to 100% by weight, and the same applies hereinafter. Among them, the DuPont impact strength of the foam can be further increased by setting the blending amount of (A-2) to 1 to 25% by weight.

Examples 4 to 6 and Comparative Example 2 both contain a modified propylene-ethylene block copolymer (A-1) and a propylene-ethylene block copolymer (B-1). It can be seen that the DuPont impact strength of the foam can be increased by setting the blending amount of 1) to 1 to 49% by weight. Among them, the DuPont impact strength of the foam can be further increased by setting the blending amount of (A-1) to 1 to 25% by weight.

Here, in all of Examples 1 to 6 and Comparative Examples 1 and 2, the MFR of the component (A) is generally in the range of 20 to 80. From the viewpoint of impact resistance, the component (A) It can be seen that it is preferable that the blending amount is 1 to 25% by weight. When emphasizing mold transferability, it is preferable that the MFR of the component (A) is approximately in the range of 20 to 80.

Each of Examples 7 to 9 includes the modified propylene-ethylene block copolymer (A-6) and the propylene-ethylene block copolymer (B-1). The blending amount of (A-6) It can be seen that the Dupont impact strength of the foam can be made higher than that of Comparative Examples 1 and 2 and about the same as or higher than that of Examples 1 to 6 by setting the content to 1 to 49% by weight. . Among them, the DuPont impact strength of the foam can be further increased by setting the blending amount of (A-6) to 1 to 25% by weight.

In Examples 7 to 9, the MFR of the component (A) is generally in the range of 1 to 20, but from the viewpoint of impact resistance, the blending amount of the component (A) is 1 to 25. It turns out that it is suitable to set it as weight%. When the mold transfer property is not so important, it is preferable that the MFR of the component (A) is approximately in the range of 1 to 20.

In the case where the component (B) has a low MFR, Example 10 and Example 11 were modified propylene-ethylene block copolymers (A-1, A-2) and propylene-ethylene block copolymers (B -3), the DuPont impact strength of the foam can be further increased as compared with Examples 3 and 6 above.

In the case where the MFR of the component (B) is high, Comparative Examples 12 to 13 are modified propylene-ethylene block copolymers (A-2, A-1) and propylene-ethylene block copolymers (B-4). In comparison with Examples 3 and 6 above, the DuPont impact strength of the foam is inferior.

(4b) When component (A) is a modified propylene homopolymer and component (B) is a propylene-ethylene block copolymer Comparative Examples 3-5, Comparative Examples 6-8, and Comparative Examples 9-11 are: As the component A), the modified propylene homopolymers (A-5), (A-4), and (A-3), respectively, and as the component (B), the propylene-ethylene block copolymer (B-1) However, it can be seen that the DuPont impact strength of the foam is inferior to that of the example containing the modified propylene-ethylene block copolymer as the component (A).

For example, in Comparative Example 4 and Example 9, the component (A) is a modified propylene homopolymer (A-5) and a modified propylene-ethylene block copolymer (A-6), respectively. Other than the above, the composition is the same including the blending amount, but the former is inferior in the DuPont impact strength of the foam.

(4c) When component (A) is a modified propylene-ethylene block copolymer and component (B) is a propylene homopolymer Comparative Examples 14 to 16 are the modified propylene-ethylene block as component (A). Copolymers (A-6), (A-2), and (A-1), and propylene homopolymer (B-2) as component (B), but modified as component (A) Compared to Examples 9, 3, and 6 containing a propylene-ethylene block copolymer and a propylene-ethylene block copolymer as component (B), it can be seen that the DuPont impact strength of the foam is inferior. However, compared with Comparative Examples 17 to 19 containing the modified propylene homopolymer as the component (A) and the propylene homopolymer as the component (B), the foam has excellent DuPont impact strength.

(4d) When component (A) is a modified propylene homopolymer, and component (B) is a propylene homopolymer Comparative Examples 17 to 19 are the modified propylene homopolymer (A- 5), including (A-4) and (A-3), and propylene homopolymer (B-2) as component (B), but overall the foam has a low DuPont impact strength. I understand.

In addition, in the blending of 100 parts by weight of the component (B), 3 parts by weight of the component (C) and 1.5 parts by weight of the component (D) without blending the component (A), injection foam molding should be satisfactorily performed. I can't. From this, it is understood that it is essential to combine the component (A) with the component (B) in carrying out the injection foam molding.

Further, FIG. 1 shows a graph in which the melt tension is plotted against the MFR obtained in each example and comparative example.

In the figure, the examples are plotted with circles (outlined), and the comparative examples are plotted with triangles (black). As a result, it can be seen that the melt tension of the resin composition of each example is equal to or less than the melt tension obtained from the following linear equation. Therefore, when the MFR of the resin composition is X, the melt tension Y of the resin composition is preferably not more than the melt tension obtained from the following linear equation from the viewpoint of impact resistance.
Y ≦ (−0.032) X + 1.91
(Y is the melt tension (gf) of the resin composition, and X is the MFR (g / 10 minutes) of the resin composition)

Claims

Conjugated diene-modified polypropylene resin (A) which is a conjugated diene-modified propylene-ethylene block copolymer having a melt flow rate measured at 230 ° C. and a load of 2.16 kg of 1 g / 10 min or more and less than 80 g / 10 min. ,as well as,
Polypropylene for injection foam molding containing a polypropylene resin (B) which is a propylene-ethylene block copolymer having a melt flow rate measured at 230 ° C. and a load of 2.16 kg of 1 g / 10 min or more and less than 80 g / 10 min. A resin composition comprising:
The content of the ethylene component in the component (A) is 1% by weight or more,
The content of the component (A) is 1 to 49% by weight and the content of the component (B) is 51 to 99% by weight with respect to the total of 100% by weight of the component (A) and the component (B).
A polypropylene resin composition for injection foam molding, wherein a melt tension measured at 200 ° C. and 10 m / min of the composition is 0.1 gf or more and less than 2.0 gf.
2. The polypropylene resin composition for injection foam molding according to claim 1, wherein the composition has a melt flow rate measured at 230 ° C. and a load of 2.16 kg of 8 g / 10 min or more and less than 80 g / 10 min.
The content of the component (A) is 1 to 25% by weight, the content of the component (B) is 75 to 99% by weight with respect to the total of 100% by weight of the component (A) and the component (B), and
The polypropylene resin composition for injection foam molding according to claim 1 or 2, wherein the melt flow rate of component (A) measured at 230 ° C and a load of 2.16 kg is 20 g / 10 min or more and less than 80 g / 10 min. .
The content of the component (A) is 1 to 25% by weight, the content of the component (B) is 75 to 99% by weight with respect to the total of 100% by weight of the component (A) and the component (B), and
The polypropylene resin composition for injection foam molding according to claim 1 or 2, wherein the melt flow rate of component (A) measured at 230 ° C and a load of 2.16 kg is 1 g / 10 min or more and less than 20 g / 10 min. .
An injection-foamed molded article of the polypropylene resin composition according to any one of claims 1 to 4.