WO2019004311A1 - Injection-molded article of polypropylene resin composition - Google Patents

Abstract

Provided is an injection-molded article which is of a polypropylene resin composition and which has excellent fluidity, flash prevention, and impact resistance. The polypropylene resin composition contains (A) a conjugated diene-modified propylene-ethylene block copolymer having a melt flow rate of 1-150 g/10 min as measured at 230ºC and a load of 2.16 kg, and (B) a polypropylene resin having a melt flow rate of 1-100 g/10 min as measured under the afore-mentioned conditions. The contained amount of (A) is 0.1-50 parts by weight and the contained amount of (B) is 99.9-50 parts by weight with respect to a total of 100 parts by weight of (A) and (B). The polypropylene resin composition has a melt flow rate of 10-100 g/10 min as measured under the afore-mentioned conditions, and a melt tension of 0.3-30 gf as measured at 200ºC and 20 m/min.

Description

Injection molded article of polypropylene resin composition

The present invention relates to an injection-molded article of a polypropylene-based resin composition.

Polypropylene resins have good physical properties and moldability, and their range of use is rapidly expanding as environmentally friendly materials. In particular, for automobile parts and the like, lightweight and highly rigid polypropylene resin products are provided. One such product is an injection molded article of polypropylene resin.

In the case of injection molding materials, high fluidization is required from the viewpoint of productivity, and this is often dealt with by formulation changes and molding condition changes.

When the injection molding material is made to be highly fluid by changing the formulation, the material intrudes into the gap between the mold division surfaces, and burrs are easily generated in the molded product. When dealing with molding condition change, it is general to increase the material injection pressure or to increase the injection speed, so the injection pressure generates a gap on the mold division surface and burrs are easily generated in the molded product . Such a tendency is remarkable in the case of large-sized injection molded products, such as injection molded products for automobiles.

Therefore, there is a demand for an injection molding material with few burrs that virtually eliminates the burrs and can be neglected, making it unnecessary or easy to remove the burrs after injection molding.

As such a material, for example, in a propylene-based resin composition containing a propylene-based resin and an elastomer and an inorganic filler, or a propylene-based resin and an inorganic filler as main components, the characteristics of the propylene-based resin Is a propylene-based resin composition in which one or both of a specific infrared absorbance ratio and a specific Mw / Mn ratio are satisfied and the characteristic value of the resin composition is within a range satisfying a specific inequality Has been proposed (Patent Document 1). Specifically, ethylene-α-olefin copolymers and styrene thermoplastic elastomers are proposed as the elastomer, and talc is proposed as the inorganic filler. However, due to the low compatibility between the propylene-based resin and the elastomer, problems such as a decrease in physical properties and appearance defects may occur, and the effect is obtained only when the elastomer is blended in an amount of 25% by weight (Example 4) or more. For example, at 20% by weight of an elastomer (Comparative Example 2), there is a problem that the anti-flashing effect is not recognized and, in addition, it can not be applied when an inorganic filler such as talc can not be blended.

In addition, crystalline polypropylene satisfying a specific MFR value range and a specific Mw / Mn ratio range; a specific MFR value range, a specific Mw / Mn ratio range, and a component having a molecular weight of 2,000,000 or more There has been proposed a polypropylene-based resin composition containing a propylene-based polymer satisfying the ratio, etc .; a thermoplastic elastomer as an optional component; an inorganic filler as an optional component; and a crystal nucleating agent (Patent Document 2). The propylene-based polymer proposed herein is a long-chain branched propylene-based polymer in which a macromer formed from an active species derived from a catalyst component is incorporated into a main chain to form a branched structure. However, when the thermoplastic elastomer and the inorganic filler are not used in combination, the effect is described only when 30% by weight (Example 1) or more of the propylene polymer is blended, and the thermoplastic elastomer and the inorganic filler are used in combination. In the case, the effect is described only when 35% by weight (Example 4) or more is blended as the total amount of the propylene-based polymer and the thermoplastic elastomer, and the anti-flashing effect at the blending amount smaller than that is described. It was unknown. In addition, the synthesis of the propylene-based polymer requires a special metal catalyst and a dedicated polymerization apparatus, which causes problems in terms of process and production cost.

As described above, it is possible to suppress or prevent burrs by using a small amount of a modifier in a polypropylene resin, that is, to obtain an injection-molded article of a polypropylene resin composition that achieves both flowability and burr prevention. It was difficult.

In particular, it has not been known that such modifiers do not reduce the impact resistance of the injection molded body by using them, or have an additional effect of improving the impact resistance.

JP 2005-194297 A JP, 2011-88955, A

An object of the present invention is to provide an injection-molded article of a polypropylene resin composition which is excellent in flowability, burr resistance and impact resistance.

The present invention is as follows.
[1] An injection-molded article of a polypropylene-based resin composition, wherein the polypropylene-based resin composition is a conjugated diene modified product having a melt flow rate of 1 to 150 g / 10 min measured at 230 ° C. under 2.16 kg load. (A) containing a high-quality propylene-ethylene block copolymer (A) and a polypropylene resin (B) having a melt flow rate of 1 to 100 g / 10 min measured at 230 ° C. and a 2.16 kg load, The content of (A) is 0.1 to 50 parts by weight and the content of (B) is 99.9 to 50 parts by weight with respect to 100 parts by weight of the total of (B) and (B). Melt flow rate measured at 230 ° C under 2.16 kg load is 10 to 100 g / 10 min, melt tension measured at 200 ° C. at 20 m / min is 0.2 to 30 gf , Injection molded articles.
[2] The injection-molded article according to the above [1], having an expansion ratio of 1.1 or less.
[3] The injection-molded article according to any one of [1] to [2], wherein the melt flow rate of the conjugated diene-modified propylene-ethylene block copolymer (A) is 10 to 100 g / 10 min.
[4] The injection molded article according to any one of the above [1] to [3], wherein the melt flow rate of the polypropylene resin (B) is 10 to 80 g / 10 min.
[5] The injection molded article according to any one of the above [1] to [4], wherein the melt flow rate of the polypropylene resin composition is 20 to 80 g / 10 min.
[6] The content of (A) is 1 to 35 parts by weight and the content of (B) is 100 parts by weight of the conjugated diene-modified propylene-ethylene block copolymer (A) and the polypropylene resin (B) in total The injection molded article according to any one of the above [1] to [5], which is 99 to 65 parts by weight.
[7] A conjugated diene-modified propylene-ethylene block copolymer (A) is a melt mixture of (a) propylene-ethylene block copolymer, (b) radical polymerization initiator, and (c) conjugated diene compound The injection molded article according to any one of the above [1] to [6].
[8] The method for producing an injection molded article according to any one of the above [1] to [7], wherein the polypropylene resin composition substantially containing no foaming agent is subjected to temperature 170 ° C. to 300 ° C. A method comprising injection molding.

The injection-molded article of the polypropylene-based resin composition of the present invention is excellent in flowability, anti-burr property, and impact resistance. Therefore, continuous and stable injection molding can be performed, and furthermore, the work of removing the burrs of the injection molded body can be omitted or simplified. In addition, the impact resistance of the obtained injection molded article is excellent. The injection molded article of the present invention is particularly suitable for large-sized injection molded articles produced using large molds. Furthermore, the injection molded article of the polypropylene resin composition of the present invention can be adjusted to a desired flowability, and a desired injection molded article can be obtained as compared with conventionally known polypropylene resins. it can.

Hereinafter, embodiments of the present invention will be described.

The injection molded article of the present invention is an injection molded article composed of a polypropylene resin composition. The polypropylene resin composition comprises a conjugated diene-modified propylene-ethylene block copolymer (A) having a melt flow rate of 1 to 150 g / 10 min measured at 230 ° C. and a load of 2.16 kg, and 230 ° C. Conjugated diene-modified propylene-ethylene block copolymer (A) and polypropylene-based resin (B) containing a polypropylene-based resin (B) having a melt flow rate of 1 to 100 g / 10 min measured under 2.16 kg load The content of the conjugated diene-modified propylene-ethylene block copolymer (A) is 0.1 to 50 parts by weight, and the content of the polypropylene resin (B) is 99.9 to 50 parts by weight with respect to a total of 100 parts by weight of B). The polypropylene-based resin composition has a melt flow rate of 10 to 100 g / 1 measured at 230.degree. C. under 2.16 kg load. Minute, melt tension measured at 200 ° C, 20 m / min 0.3 to 30 gf (melt flow rate 10 to less than 40 g / 10 min) or 0.2 to 30 gf (melt flow rate 40 or more) 100 g or less / 10 minutes).

The injection molded article of the present invention is preferably a substantially non-foamed injection molded article. A foam produced by blending a foaming agent with the resin composition and foaming at the time of molding is not included in the scope of the injection molded article of the present invention. However, a very small amount of a foaming agent may be mixed for purposes other than foaming, a substance that acts as a foam may be mixed as an impurity, or a compounding agent blended for a purpose other than foaming may be thermally decomposed during molding, etc. Since bubbles may be generated as a result of defining the expansion ratio of the injection molded article, the expansion ratio of the injection molded article of the present invention is not more than 1.2 times and not more than 1.1 times. Is preferably 1.05 times or less, more preferably 1.01 times or less. Further, it is most preferable that the foam is not substantially foamed, that is, the foaming ratio is 1.00.

<Conjugated diene-modified propylene-ethylene block copolymer (A)>
The conjugated diene-modified propylene-ethylene block copolymer (A) of the present invention is prepared by reacting a propylene-ethylene block copolymer with a conjugated diene compound to introduce a branched structure into the propylene-ethylene block copolymer. It is a resin obtained by polymerizing this.

The conjugated diene-modified propylene-ethylene block copolymer (A) of the present invention has a melt flow rate of 1 to 150 g / 10 min measured under the conditions of 230 ° C. and a 2.16 kg load. If the melt flow rate of the component (A) is less than 1 g / 10 minutes, there is no problem from the viewpoint of suppressing burrs, but the flowability of the resin composition is insufficient, such as short shot in injection molding with a large mold. May cause problems. When the melt flow rate of the component (A) exceeds 150 g / 10 min, mixing with the component (B) may be insufficient or the measurement process in injection molding in dry blending may be unstable. Moreover, when the melt flow rate of the component (A) exceeds 150 g / 10 min, it becomes difficult to adjust the melt flow rate of the composition to the range described later, and mixing with the component (B) is not possible. If this is sufficient, the composition becomes nonuniform, and the effect of suppressing burrs is diminished, which is not preferable. The melt flow rate of the component (A) is preferably 3 to 100 g / 10 min, more preferably 5 to 80 g / 10 min.

Here, the melt flow rate (hereinafter sometimes abbreviated as "MFR") means 230 ° C., using a melt indexer F-F01 (manufactured by Toyo Seiki Seisakusho Co., Ltd.) in accordance with JIS K 7210: 1999. A value obtained by converting the amount of resin extruded from a die in a fixed time under the condition of a 2.16 kg load into the amount of resin extruded in 10 minutes. The converted value was calculated by MFR automatic calculation processing (method B). The calculation formula is as follows. The method was applied even if the melt flow rate exceeded 50 g / 10 min.

MFR (g / 10 min) = (427 × L × ρ) / t
L (interval of test conditions): 3 (cm)
ρ (melt density at the test temperature): A value (g / cm ³ ) calculated by the following equation using the cutting method, but た だ し 0.75 (g / cm ³ ) if the cutting method is not possible = M / (0.711 x L)
m: mass (g) of the sample that has flowed out by moving the above-mentioned interval L, which is measured by a cutting method
L: Same as the above interval t (interval moving time): actual measured value (seconds)
That is, when the clipping method can be applied, it may be calculated by the following formula.
MFR (g / 10 min) = (600 × m) / t
The conjugated diene-modified propylene-ethylene block copolymer (A) of the present invention is obtained by melt mixing (a) a propylene-ethylene block copolymer, (b) a radical polymerization initiator and (c) a conjugated diene compound. Are preferred. This molten mixture is excellent in that it can be manufactured inexpensively without the need for expensive equipment.

<Propylene-ethylene block copolymer (a)>
The propylene-ethylene block copolymer (a) used to obtain the conjugated diene-modified propylene-ethylene block copolymer (A) is mainly composed of ethylene in a propylene-based linear polymer. And ethylene-propylene rubber-like copolymers are dispersed to form a sea-island structure. Such propylene-based polymers are conventionally referred to as impact-resistant polypropylene and block polypropylene etc. in Japan, but they are not block copolymers in a chemical sense. In the present invention, the propylene-ethylene block copolymer (a) is a homopolymer of propylene or a copolymer (a1) mainly composed of propylene, a homopolymer (a2) of ethylene and / or ethylene and a carbon number It is preferable that it is a mixture containing a copolymer (a3) with 3 to 10 α-olefins. 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) is an ethylene-propylene rubber-like copolymer It corresponds to union.

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

The propylene-ethylene block copolymer (a) contains 1% by weight or more of the ethylene component from the viewpoint of impact resistance etc., but preferably 3% by weight or more, 5% 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 of propylene and ethylene, and a monomer copolymerizable with propylene. As such a monomer copolymerizable with propylene, for example, 1-butene, isobutene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3,4-dimethyl Α-olefins of 4 to 12 carbon atoms such as -1-butene, 1-heptene, 3-methyl-1-hexene, 1-octene and 1-decene; cyclopentene, norbornene, tetracyclo [6,2,11,8, Cyclic olefins such as 13,6] -4-dodecene; 5-methylene-2-norbornene, 5-ethylidene-2-norbornene, 1,4-hexadiene, methyl-1,4-hexadiene, 7-methyl-1,6 Dienes such as octadiene; vinyl chloride, vinylidene chloride, acrylonitrile, vinyl acetate, acrylic acid, methacrylic acid, maleic acid, acrylic acid Ethyl Le acid, 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. Among them, α-olefins are preferable and 1-butene is more preferable in terms of improvement of cold resistance, low cost and the like.

Commercially available propylene-ethylene block copolymers (a) are, for example, J709UG (MFR = 55), J708UG (MFR = 45), J830HV (MFR = 30), J717ZG (MFR =, manufactured by Prime Polymer Co., Ltd.). 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 WO 2015/060201, J708UG has an ethylene-based polymer content of 14% by mass, and can be suitably used in the present invention.

<Radical polymerization initiator (b)>
Examples of the radical polymerization initiator (b) used to obtain the conjugated diene-modified propylene-ethylene block copolymer (A) generally include peroxides and azo compounds, but the propylene-ethylene block copolymer Those having the ability to extract hydrogen from (a) or conjugated diene compound (c) are preferred. Although it does not specifically limit, For example, organic peroxides, such as ketone peroxide, peroxy ketal, a hydroperoxide, a dialkyl peroxide, a diacyl peroxide, peroxy dicarbonate, peroxy ester, etc. are mentioned. Among them, those having high hydrogen abstraction ability are particularly preferable, for example, 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane Peroxyketal such as n-butyl 4,4-bis (t-butylperoxy) valerate, 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-butyl peroxide, 2,5- Dialkyl peroxides such as dimethyl-2,5-di (t-butylperoxy) -3-hexyne, and diacyl peroxides such as benzoyl peroxide Xide, t-butylperoxy octoate, t-butylperoxyisobutyrate, t-butylperoxylaurate, t-butylperoxy 3,5,5-trimethylhexanoate, t-butylperoxyisopropylcarbonate And peroxy esters such as 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-butylperoxyacetate, t-butylperoxybenzoate, and di-t-butylperoxyisophthalate. Be These may be used alone or in combination of two or more.

The addition amount of the radical polymerization initiator (b) used to obtain the conjugated diene-modified propylene-ethylene block copolymer (A) is 100 parts by weight of the propylene-ethylene block copolymer (a), 0.05 parts by weight or more and 10 parts by weight or less are preferable, and 0.2 parts by weight or more and 5 parts by weight or less are more preferable. If the addition amount of the radical polymerization initiator is less than 0.05 parts by weight, the modification may be insufficient, and if it exceeds 10 parts by weight, molecular chain cleavage takes priority over the modification, and the desired modification There may be no quality effect.

<Conjugated diene compound (c)>
Examples of the conjugated diene compound (c) used to obtain the conjugated diene-modified propylene-ethylene block copolymer (A) include butadiene, isoprene, 1,3-heptadiene, 2,3-dimethylbutadiene, 5-dimethyl-2,4-hexadiene and the like. These may be used alone or in combination. Among these, butadiene and isoprene are preferable from the viewpoints of being inexpensive, easy to handle, and capable of uniformly advancing the reaction.

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 more preferably 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 amount of conjugated diene compound added is less than 0.01 parts by weight, reforming may be insufficient, and if it exceeds 5 parts by weight, fluidity may be insufficient.

In producing the conjugated diene-modified propylene-ethylene block copolymer (A), a monomer copolymerizable with the conjugated diene compound may be used in combination with the conjugated diene compound. As such copolymerizable monomers, for example, vinyl chloride, vinylidene chloride, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, vinyl acetate, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, acrylic acid Metal salts, metal methacrylates, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, acrylic esters such as stearyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, methacrylic acid 2 -Ethylhexyl, stearyl methacrylate and the like.

<Conditions for Production of Conjugated Diene-Modified Propylene-Ethylene Block Copolymer (A)>
When producing the conjugated diene-modified propylene-ethylene block copolymer (A), the addition amount of the radical polymerization initiator (b) is 0.1 times or more of the addition amount of the conjugated diene compound (c), 10 If it is twice or less (by weight), the melt flow rate of the conjugated diene-modified propylene-ethylene block copolymer (A) can be adjusted relatively easily in the range of 1 or more and 150 or less. The addition amount of the radical polymerization initiator (b) is preferably 0.5 times or more and 7.5 times or less the addition amount of the conjugated diene compound (c), more preferably 0.75 times or more and 5 times or less It is.

Device for reacting propylene-ethylene block copolymer (a), radical polymerization initiator (b) and conjugated diene compound (c) to obtain conjugated diene-modified propylene-ethylene block copolymer (A) As the roll, co-kneader, Banbury mixer, Brabender, single-screw extruder, kneading machine such as twin screw extruder, twin screw surface renewal machine, horizontal stirrer such as twin screw multi disk device, double helical ribbon stirrer And vertical stirrers, etc. Among these, it is preferable to use a kneader, and in particular, an extruder is preferable from the viewpoint of productivity.

In order to obtain a conjugated diene-modified propylene-ethylene block copolymer (A), the propylene-ethylene block copolymer (a), a radical polymerization initiator (b) and a conjugated diene compound (c) are mixed and kneaded (stirred (stirred) There is no particular limitation on the order or method to be performed. 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) After melt-kneading (stirring), the radical initiator (b) and the conjugated diene compound (c) may be mixed simultaneously or separately, collectively or in portions. The temperature of the kneading (stirring) machine is preferably 130 to 300 ° C. in 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, a conjugated diene-modified propylene-ethylene block copolymer (A) can be produced. The shape and size of the conjugated diene-modified propylene-ethylene block copolymer (A) to be produced are not limited and may be in the form of pellets.

<Polypropylene resin (B)>
A polypropylene resin (B) points out what has crystallinity. Polypropylene resins modified with conjugated dienes are not included in the concept of polypropylene resins (B). The polypropylene resin (B) may be either a homopolymer of propylene or a copolymer of a monomer copolymerizable with propylene and propylene. In addition, a mixture of a homopolymer and a copolymer of propylene may be used. As the copolymer, either a so-called block copolymer or a random copolymer may be used. As the copolymer, a copolymer containing 51% by weight or more of propylene is preferable, and 75 weight of propylene is preferable in that the crystallinity, rigidity, chemical resistance and the like which are the characteristics of the polypropylene resin are maintained. Copolymers containing at least% are more preferred. As monomers copolymerizable with propylene, the above-mentioned monomers can be used.

Specific examples of the preferred polypropylene resin (B) include homopolymers of propylene (homopolymers), random copolymers of propylene and ethylene, block copolymers of propylene and ethylene, and other propylene and ethylene copolymers. It can be mentioned. You may mix and use these.

In the propylene-ethylene copolymer, a polymer mainly composed of ethylene and an ethylene-propylene rubber-like copolymer are dispersed in a linear polymer mainly composed of propylene to form a sea-island structure Such a propylene-based polymer may be used. Such propylene-based polymers are conventionally referred to as impact-resistant polypropylene and block polypropylene etc. in Japan, but they are not block copolymers in a chemical sense.

The melt flow rate of the polypropylene resin (B) measured under the conditions described above is 1 to 100 g / 10 min, preferably 10 to 80 g / 10 min, and more preferably 20 to 70 g / 10 min. When the melt flow rate of the polypropylene resin (B) is in the above range, even when the clearance of the mold cavity has a thin portion of, for example, about 1 to 2 mm when manufacturing the injection molded body, relatively low pressure It is possible to fill the molten resin in the mold and there is a tendency that continuous and stable injection molding can be performed. Moreover, when the melt flow rate of the component (B) exceeds 100 g / 10 min, it becomes difficult to adjust the melt flow rate of the composition to the range described later, and mixing with the component (A) is not sufficient. If this is sufficient, the composition becomes nonuniform, and the effect of suppressing burrs is diminished, which is not preferable. If the melt flow rate of the component (B) is less than 1 g / 10 min, although there is no problem from the viewpoint of suppressing burrs, molding defects such as short shots are likely to occur, or excessive injection pressure is required. This is not preferable because another molding failure may occur.

<Polypropylene-based resin composition>
The polypropylene-based resin composition constituting the injection molded article of the present invention has a melt flow rate of 10 to 100 g / 10 min, preferably 15 to 80 g / 10 min, more preferably 20 to 100 g, measured under the conditions described above. 70 g / 10 min.

In addition, the polypropylene-based resin may be used to obtain a relatively small molded product and do not require much flowability, or to increase mold transferability by applying a resin pressure during molding to a certain extent. The melt flow rate of the composition is preferably 10 to 60 g / 10 minutes, more preferably 10 to 50 g / 10 minutes, still more preferably 10 to 40 g / 10 minutes. In addition, when it is necessary to obtain a relatively medium-sized molded product and it is necessary to have both fluidity and application of a resin pressure at the time of molding, the melt flow rate of the polypropylene resin composition is preferably 20. It is about -75 g / 10 min, more preferably 25-70 g / 10 min, still more preferably 30-65 g / 10 min.

When the melt flow rate of the polypropylene resin composition is in the above range, even when the mold cavity has a thin portion with a clearance of, for example, about 1 to 2 mm when manufacturing an injection molded body, relatively low pressure It is possible to fill the molten resin in the mold and there is a tendency that continuous and stable injection molding can be performed. When the melt flow rate of the composition exceeds 100 g / 10 min, the effect of suppressing the burrs of the component (A) is undesirably reduced. When the melt flow rate of the composition is less than 10 g / 10 min, although there is no problem in suppressing the burrs, molding defects such as short shots are likely to occur, or excessive injection pressure is required. It is not preferable because molding defects may occur. The melt flow rate of the resin composition is a numerical value measured after sufficiently melt-kneading each component, and is a melt exhibited by each of the conjugated diene-modified propylene-ethylene block copolymer (A) and the polypropylene resin (B). It can be easily adjusted depending on the flow rate, the blending amount of each component, and the like.

The polypropylene-based resin composition has a melt tension of 0.3 to 30 gf (when the melt flow rate of the resin composition is 10 to less than 40 g / 10 minutes) or 0.2 measured at 200 ° C. and 20 m / min. And 30 gf (when the melt flow rate of the resin composition is 40 or more and 100 g or less / 10 minutes).

When the melt flow rate of the resin composition is 10 or more and less than 40 g / 10 minutes, the melt tension of the resin composition is preferably 0.4 to 20 gf, more preferably 0.5 to 10 gf, and still more preferably It is 0.5 to 5.0 gf.

When the melt flow rate of the resin composition is 40 to 100 g / 10 minutes, the melt tension of the resin composition is preferably 0.3 to 20 gf, more preferably 0.4 to 10 gf, and still more preferably It is 0.5 to 5.0 gf.

When the melt tension of the polypropylene-based resin composition is in the above range, the injection-molded product can achieve an excellent burr suppression effect. The melt tension of the resin composition is a numerical value measured after sufficiently melt-kneading each component, and the melt flow exhibited by each of the conjugated diene-modified propylene-ethylene block copolymer (A) and the polypropylene resin (B) It can be easily adjusted depending on the rate, type, combination, amount of each component, and the like.

In the present application, melt tension (hereinafter sometimes abbreviated as "MT") is measured as follows. Using a Capillograph (made by Toyo Seiki Seisakusho Co., Ltd.) equipped with a melt tension measurement attachment and equipped with a φ10 mm cylinder fitted with an orifice with φ1 mm and 10 mm in length at the tip, piston lowering speed 10 mm The load applied to the pulley with a load cell was measured over time while the strand discharged from the die when being lowered at a rate of 1 minute was pulled on a load cell equipped pulley under 520 mm and pulled at a speed of 20 m / min. The maximum value and the minimum value of the load obtained after the deflection of the load was approximately stabilized were measured, and their average value was taken as the melt tension. When the strand is broken, it can not be measured, and when the load applied to the pulley with load cell is too low to be sensed, the melt tension is set to 0.

Melt tension refers to the tension required to deform the molten resin, whereas melt flow rate is a measure of the flowability of the molten resin, so both are different concepts. As shown in the following comparative example, even if the melt flow rate of the resin composition is within the range defined in the present application, desired melt suppression is achieved when the melt tension of the resin composition is not within the range defined herein. The effect can not be achieved. It has not been known at all until now that the burrs of the injection molded article can be reduced by adjusting the melt tension of the resin composition, and it is a finding that the present inventors have found for the first time. The present invention is a mechanism capable of suppressing the burrs of the injection molded article by using predetermined components (A) and (B) and adjusting both the melt flow rate and the melt tension of the resin composition within a predetermined range. Although it is unclear at present, the increase in the elasticity of the molten resin makes it difficult for the molten resin to penetrate into the gaps of the mold, and as a result, it is considered that the generation of burrs becomes difficult. Moreover, it is thought that the crystallization promotion effect achieved by addition of (A) component which is mentioned later is also contributed.

The conjugated diene-modified propylene-ethylene block copolymer (A) relative to 100 parts by weight in total of the conjugated diene-modified propylene-ethylene block copolymer (A) and the polypropylene-based resin (B) in the polypropylene resin composition The content of) is 0.1 to 50 parts by weight, and the content of the polypropylene resin (B) is 99.9 to 50 parts by weight. When the compounding ratio is in the above range, an injection molded article satisfying both the flowability and the anti-burr effect can be provided at low cost. If the compounding ratio is outside the above range, for example, if the content of the conjugated diene-modified propylene-ethylene block copolymer (A) is less than 0.1 parts by weight, a sufficient burr prevention effect tends not to be obtained, If it exceeds 50 parts by weight, the flowability tends to be reduced and the appearance of the molded product tends to be deteriorated. From the viewpoint of fluidity and anti-burr effect, the content of (A) is preferably 0.5 to 45 parts by weight, the content of (B) is preferably 99.5 to 55 parts by weight, and the content of (A) is 1 to 35 parts The content of (B) is more preferably 99 to 65 parts by weight, the content of (A) is 2 to 25 parts by weight, the content of (B) is more preferably 98 to 75 parts by weight, and the content of (A) is The content of 3 to 15 parts by weight and the content of (B) is particularly preferably 97 to 85 parts by weight.

<Other additives>
The polypropylene resin composition constituting the injection molded article of the present invention is a high density polyethylene resin other than the polypropylene resin different from any of the components (A) and (B) to the extent that the effects of the present invention are not impaired. It may further contain a resin, high-pressure low density polyethylene resin, linear low density polyethylene resin, ethylene-α-olefin copolymer, olefin elastomer, styrene elastomer, and other thermoplastic resins. .

The said polypropylene resin composition is an antioxidant, a metal deactivator, a phosphorus process stabilizer, an ultraviolet absorber, an ultraviolet stabilizer, a fluorescent brightener, a metal soap, in the range which does not impair the effect of this invention. In addition, additives such as stabilizers such as acid adsorbents, crosslinking agents, chain transfer agents, nucleating agents, plasticizers, lubricants, fillers, reinforcing materials, pigments, dyes, flame retardants, antistatic agents, etc. It may be. However, the polypropylene resin composition does not contain a foaming agent.

<Injection molded body>
The present invention relates to an injection-molded article of the polypropylene-based resin composition. The injection molded article of the present invention is excellent in flowability and anti-burr property. Therefore, it is particularly suitable for large-sized injection molded articles manufactured using large molds. Furthermore, since the injection molded article of the present invention can be adjusted to a desired flowability and can suppress burrs, compared with injection molded articles of conventionally known polypropylene resins. The desired injection molded body can be obtained.

The injection molding method that can be used to produce the injection molded article of the present invention is not particularly limited, and known methods can be applied. Specific molding conditions can be appropriately determined in consideration of the melt flow rate and melt tension exhibited by the polypropylene resin composition, the type of molding machine, the shape of a mold, and the like.

Specifically, the resin temperature is preferably 170 to 300 ° C., more preferably 180 to 280 ° C., still more preferably 190 to 270 ° C., and the mold temperature is preferably 10 to 100 ° C., more preferably 20 to 80 ° C is illustrated. 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 / sec, and an injection pressure of 10 to 200 MPa.

The injection molded article of the present invention can be used for various applications, and in particular, as a large injection molded article in which burrs are suppressed, automobile parts, exterior parts for household electric appliances, exterior parts for industrial machinery, construction It can be suitably used for an exterior member for construction, an interior member for construction, a protection member for impact absorption, a casing for electronic parts, and the like.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

The test methods and criteria used for the various evaluation methods in the examples and comparative examples are as follows.

(1) Melt flow rate (MFR)
In accordance with JIS K 7210: 1999, using Melt Indexer F-F01 (manufactured by Toyo Seiki Seisakusho Co., Ltd.), under the conditions of 230 ° C. and a load of 2.16 kg, the amount of resin extruded from the die in a fixed time is 10 The value converted into the amount of resin extruded in one minute was taken as the melt flow rate. The converted value was calculated by MFR automatic calculation processing (method B). The calculation formula is as follows. The method was applied even if the melt flow rate exceeded 50 (g / 10 min).

MFR (g / 10 min) = (427 × L × ρ) / t
L (interval of test conditions): 3 (cm)
溶 融 (melt density at the test temperature): A value calculated by the following equation using the cutting method, provided that 0.75 (g / cm ³ ) is possible if the cutting method is not possible: == m / (0. 711xL)
m: mass (g) of the sample that has flowed out by moving the above-mentioned interval L, which is measured by a cutting method
L: Same as the above interval t (interval moving time): actual measured value (seconds)
That is, when the clipping method can be applied, it may be calculated by the following formula.

MFR (g / 10 min) = (600 × m) / t
(2) Melt tension (MT)
Using a Capillograph (made by Toyo Seiki Seisakusho Co., Ltd.) equipped with a melt tension measurement attachment and equipped with a φ10 mm cylinder fitted with an orifice with φ1 mm and 10 mm in length at the tip, piston lowering speed 10 mm The load applied to the pulley with a load cell was measured over time while the strand discharged from the die when being lowered at a rate of / minute was pulled on a pulley with a load cell under 370 mm or 520 mm and pulled at a speed of 20 m / min. The maximum value and the minimum value of the load obtained after the deflection of the load was approximately stabilized were measured, and their average value was taken as the melt tension. When the strand is broken, it can not be measured, and when the load applied to the pulley with load cell is too low to be sensed, the melt tension is set to 0.

(3) Crystallization temperature 4 to 10 mg of a sample to be measured from room temperature to 230 using a differential scanning calorimeter Q1000 manufactured by TA Instruments Japan Co., Ltd. according to a measuring method in accordance with JIS K 7121 (1987). The temperature is raised at a rate of 20 ° C / min to 0 ° C, kept at 230 ° C for 5 minutes to melt, then cooled at a rate of 10 ° C / min from 230 ° C to 0 ° C to obtain a DSC curve of crystallization behavior The In the obtained DSC curve, the temperature at which the calorific value is maximum at the main crystallization peak was taken as the crystallization temperature.

(4) Burr evaluation described in Tables 3 and 4 In a mold for evaluating burrs having a disc-shaped cavity of 50 mm in diameter × 2.5 mm in thickness, using an injection molding machine (IS-100 IV manufactured by Toyo Machine Metals Co., Ltd.) And injection molding at a filling pressure of 100 MPa. When the resin composition could not be completely filled by the pressure, evaluation was not possible due to molding failure.

Burr length (burr length) generated in the injection molded body by slits (clearance) 0.01 mm, 0.02 mm, 0.03 mm or 0.04 mm × width 4 mm provided on the circumferential part of the cavity Was measured using a loupe. The shorter the burr length, the better the effect of suppressing the occurrence of burr (burr characteristics).

As for the burr characteristics, Table 3 shows specific numbers of burr lengths. In Table 4, the following criteria were evaluated.

(Table 4)
:: no burrs observed ~ less than 0.2 mm burr length x: burr length 0.2 mm or more (5) Dupont impact test Above except using a flat plate mold with one pin gate at the center of the bottom Under the same conditions as (4), a flat injection molded article was prepared.

Using a Dupont impact tester (manufactured by Yasuda Seiki Seisakusho Co., Ltd.), the 50% fracture height was determined by the Staircase method with a constant falling weight, and the energy value was calculated from the load at that time. The falling load was 300 g, 700 g, or 1000 g, and the energy value was calculated according to JIS K 7211. Impact resistance was evaluated based on the following criteria.
○: Among the test samples, those with good impact resistance Δ: Among the test samples, those with poor impact resistance ×: Among the test samples, those with the lowest impact resistance <Conjugated diene-modified propylene -Preparation of ethylene block copolymer (A)>
(Production Example 1)
(A) 100 parts by weight of a propylene-ethylene block copolymer (a-1) having a melt flow rate of 5 g / 10 min as a propylene-ethylene block copolymer, and (b) t-butylperoxy as a radical polymerization initiator 1.1 parts by weight of isopropyl carbonate is supplied to a 46 mm φ twin-screw extruder (L / D = 62) at 70 kg / hour and 0.77 kg / hour respectively from the hopper prepared respectively, and the cylinder temperature Melt-kneaded at 200 ° C., 0.42 parts by weight of isoprene as a conjugated diene compound (c) was supplied at a rate of 0.294 kg / hour using a metering pump from the press-in portion provided in the middle, and the biaxial extrusion was performed By melt-kneading in a press, pellets of a conjugated diene-modified propylene-ethylene block copolymer (A-1) were obtained. MFR = 9 g / 10 min.

(Production Example 2)
(A) 100 parts by weight of a propylene-ethylene block copolymer (a-2) (containing 14% by weight of an ethylene component) having a melt flow rate of 45 g / 10 min as a propylene-ethylene block copolymer, (b) radical polymerization initiation As in Preparation Example 1 except that 1.1 parts by weight of t-butylperoxyisopropyl carbonate as the curing agent and 0.41 parts by weight of isoprene as the conjugated diene compound (c) were used. A diene-modified propylene-ethylene block copolymer (A-2) was obtained. MFR = 40 g / 10 min.

(Production Example 3)
(A) 100 parts by weight of a propylene-ethylene block copolymer (a-2), (b) 1.1 parts by weight of a blending amount of t-butylperoxyisopropyl carbonate as a radical polymerization initiator, (c) a conjugated diene compound A conjugated diene-modified propylene-ethylene block copolymer (A-3) was obtained in the same manner as in Production Example 1 except that the supply amount of isoprene was 0.32 parts by weight. MFR = 60 g / 10 min.

(Production Comparative Example 1)
(A) A propylene homopolymer (for injection molding) having a melt flow rate of 8 g / 10 min instead of a propylene-ethylene block copolymer, (b) a blending amount of t-butylperoxyisopropyl carbonate as a radical polymerization initiator Conjugated diene-modified polypropylene resin (A-4) in the same manner as in Production Example 1 except that the amount of isoprene supplied was changed to 0.75 parts by weight and (c) conjugated diene compound to 0.6 parts by weight. I got MFR = 7 g / 10 min.

(Production Comparative Example 2)
(A) Propylene homopolymer (for injection molding) having a melt flow rate of 45 g / 10 min instead of propylene-ethylene block copolymer, (b) Blending amount of t-butylperoxyisopropyl carbonate as a radical polymerization initiator Conjugated diene-modified polypropylene resin (A-5) in the same manner as in Production Example 1 except that the amount of isoprene supplied was changed to 1.1 parts by weight and (c) conjugated diene compound to 0.55 parts by weight. I got MFR = 43 g / 10 min.

(Production Comparative Example 3)
(A) Propylene homopolymer (for injection molding) having a melt flow rate of 45 g / 10 min instead of propylene-ethylene block copolymer, (b) Blending amount of t-butylperoxyisopropyl carbonate as a radical polymerization initiator Conjugated diene-modified polypropylene-based resin (A-6) in the same manner as in Production Example 1 except that the amount of isoprene supplied was changed to 1.1 parts by weight and (c) conjugated diene compound to 0.5 parts by weight. I got MFR = 60 g / 10 min.

 

 

<Polypropylene resin (B)>
The following were used as a polypropylene resin (B).
(B-1) Propylene-ethylene block copolymer having a melt flow rate of 30 g / 10 min (manufactured by Prime Polymer, J830 HV)
(B-2) Propylene-ethylene block copolymer having a melt flow rate of 55 g / 10 min (manufactured by Prime Polymer, J709QG)
(B-3) Propylene homopolymer having a melt flow rate of 30 g / 10 min (manufactured by Prime Polymer, J107G)
(B-4) Propylene homopolymer having a melt flow rate of 60 g / 10 min (manufactured by Prime Polymer, S119)
The propylene-ethylene block copolymers described in (B-1) and (B-2) are, among linear polymers mainly composed of propylene, polymers mainly composed of ethylene, and ethylene -A propylene-based polymer in which a propylene-rubbery copolymer is dispersed to form a sea-island structure. In Japan, it is customary to call block polypropylene etc.

 

 

<Preparation of injection molded body>
(Examples 1 to 23, Comparative Examples 1 to 4)
Conjugated diene-modified propylene-ethylene block copolymer (A), polypropylene resin (B), and color master batch as a coloring agent [product made by Dainichiseika, die color] according to the type and composition ratio shown in Table 3 PP-M77255, black, 3 parts by weight (the total of (A) and (B) was 100 parts by weight) was dry-blended. From the obtained dry blend, according to the item of the above-mentioned flash evaluation, an injection molded article was manufactured under the temperature conditions described in Table 3, and the degree of the flash was evaluated. The obtained results are shown in Table 3.

In Comparative Examples 1 to 4, injection molded bodies were produced in the same manner as in each Example except that the conjugated diene-modified propylene-ethylene block copolymer (A) was not used, and the degree of burrs was evaluated. .

The obtained results are shown in Table 3.

<Preparation of composition pellet for evaluation>
Conjugated diene-modified propylene-ethylene block copolymer (A), polypropylene resin (B), and color master batch as a coloring agent [product made by Dainichiseika, die color] according to the type and composition ratio shown in Table 3 PP-M77255, black, 3 parts by weight (the total of (A) and (B) was 100 parts by weight) was dry-blended.

The dry-blended pellet mixture was supplied from a hopper at a rate of 9 kg / hour to a 32 mmφ twin-screw extruder (L / D = 25), and melt-kneaded at a cylinder temperature of 200 ° C. to obtain pellets of the composition. The composition pellet was subjected to physical property measurement of melt flow rate (MFR), melt tension (MT), and crystallization temperature.

 

 

From Comparative Example 1, it can be seen that the propylene-ethylene block copolymer (B-1) is a resin which is prone to burrs. Here, as seen in Example 1, in (B-1), 3 parts by weight of a conjugated diene-modified propylene-ethylene block copolymer (A-1) (however, (A) component and (B) component It was found that the effect of suppressing burrs is exhibited by blending 100 parts by weight of the total of the same. Also, as seen in Examples 2 and 3, increasing the blending amount of the component (A-1) to 10 to 20 parts by weight showed a tendency to increase the effect.

Moreover, instead of (A-1), the case where the more fluid (A) component, that is, (A-2) in Examples 4 to 6 or (A-3) in Examples 7 to 9 is used In the same manner, it was also found that the effect of suppressing burrs was expressed.

It can be seen from Comparative Example 2 that the propylene-ethylene block copolymer (B-2) has a higher fluidity than the resin (B-1) and is a resin that is more likely to have burrs. Here, as shown in Examples 10 to 17, 3 to 20 parts by weight of a conjugated diene-modified propylene-ethylene block copolymer (A-1) to (A-3) is blended with (B-2) It was recognized that the effect which suppresses burrs was expressed by this.

Similarly, Comparative Examples 3 and 4 show that the propylene homopolymers (B-3) and (B-4) are resins that are prone to burrs. However, as seen in Examples 18 to 23, by blending 20 parts by weight of the conjugated diene-modified propylene-ethylene block copolymer (A-1) to (A-3) with each component (B), It was found that the effect of suppressing burrs was developed.

As can be seen from Examples 1 to 9 and 18 to 21, the MFR of the resin composition is in the range of 20 to 40 g / 10 min, and the MT (200 ° C., 20 m / min) is in the range of 0.3 to 30 gf Occasionally, it was recognized that the remarkable effect that a burr | flash was suppressed was expressed by the burr | flash evaluation in clearance 0.02 mm. Among them, as in Examples 1, 4 and 7, even when only 3 parts by weight of the component (A) was added, the above effect was observed.

Also, from Examples 10 to 17 and 22 to 23, the MFR of the resin composition is in the range of 40 to 60 g / 10 min, and the MT (200 ° C., 20 m / min) is in the range of 0.2 to 30 gf Occasionally, it was recognized that the remarkable effect that a burr | flash was suppressed was expressed by the burr | flash evaluation in clearance 0.02 mm.

(Comparative Examples 5 to 10)
In the type and composition ratio shown in Table 4, conjugated diene-modified propylene homopolymer (A '), polypropylene resin (B), and color master batch as a coloring agent (manufactured by Dainichiseika Seiyaku, die color PP- M77255, black, 3 parts by weight (the total of (A ') and (B) was 100 parts by weight) was dry-blended. From the obtained dry blend, according to the item of flash evaluation described above, the clearance of the slit was 0.02 mm, and an injection molded article was produced under the temperature conditions described in Table 4, and the degree of flash was evaluated. Further, according to the item of the Dupont impact test described above, a flat injection molded article was manufactured under the temperature conditions described in Table 4, and the impact resistance was evaluated. Furthermore, composition pellets were prepared as described above to measure the melt flow rate. The obtained results are shown in Table 4.

Further, in Examples 3, 6, 9, 12, 14, and 17 as well, in accordance with the items of the Dupont impact test described above, flat-plate injection molded articles were produced under the temperature conditions described in Table 4, and impact resistance was evaluated. The obtained results are shown in Table 4.

 

 

From the results of Table 4, each of the examples using (A-1) to (A-3) which are conjugated diene-modified propylene-ethylene block copolymers (A) are conjugated diene-modified propylene homopolymers ( It can be seen that the impact resistance is excellent as compared with each comparative example using (A-4) to (A-6) which are A ').

Claims (8)

An injection molded article of a polypropylene resin composition,
The polypropylene-based resin composition is
A conjugated diene-modified propylene-ethylene block copolymer (A) having a melt flow rate of 1 to 150 g / 10 min measured at 230 ° C. and a load of 2.16 kg;
And a polypropylene resin (B) having a melt flow rate of 1 to 100 g / 10 min measured at 230 ° C. under a load of 2.16 kg,
The content of the conjugated diene-modified propylene-ethylene block copolymer (A) is 0.1 to 100 parts by weight in total of the conjugated diene-modified propylene-ethylene block copolymer (A) and the polypropylene resin (B). 50 parts by weight, the content of the polypropylene resin (B) is 99.9 to 50 parts by weight,
The polypropylene resin composition has a melt flow rate of 10 to 100 g / 10 min measured at 230 ° C. and a 2.16 kg load, and a melt tension of 0.2 to 30 gf measured at 200 ° C. and 20 m / min. Is an injection molded body. The injection molded article according to claim 1, wherein the expansion ratio is 1.2 times or less. The injection-molded article according to claim 1, wherein the melt flow rate of the conjugated diene-modified propylene-ethylene block copolymer (A) is 10 to 100 g / 10 min. The injection molded article according to any one of claims 1 to 3, wherein the melt flow rate of the polypropylene resin (B) is 10 to 80 g / 10 min. The injection molded article according to any one of claims 1 to 4, wherein the melt flow rate of the polypropylene resin composition is 20 to 80 g / 10 min. The content of the conjugated diene-modified propylene-ethylene block copolymer (A) is 1 to 35 weight with respect to a total of 100 parts by weight of the conjugated diene-modified propylene-ethylene block copolymer (A) and the polypropylene resin (B) The injection-molded article according to any one of claims 1 to 5, wherein the content of the polypropylene resin (B) is 99 to 65 parts by weight. The conjugated diene modified propylene-ethylene block copolymer (A) is a melt mixture of (a) a propylene-ethylene block copolymer, (b) a radical polymerization initiator, and (c) a conjugated diene compound. An injection molded article according to any one of Items 1 to 6. A method of producing the injection molded article according to any one of claims 1 to 7, comprising:
Injection-molding the polypropylene-based resin composition substantially free of a foaming agent at a temperature of 170 ° C. to 300 ° C.