JPS6367496B2 - - Google Patents

Description

[Detailed description of the invention]

[] Object of the Invention The present invention relates to a resin composition. More specifically, it relates to a resin composition made by mixing (A) an ethylene-propylene block copolymer and (B) a linear copolymer of ethylene and α-olefin having short chain branches. The object of the present invention is to provide a resin composition having excellent low-temperature impact resistance. [] Background of the Invention For some time now, compositions obtained by blending olefin-based synthetic resins mainly composed of olefins such as ethylene polymers and propylene polymers and/or synthetic rubbers have been used in a wide variety of fields. It's being used. These compositions have low-temperature impact resistance, moldability, surface gloss of molded products, heat resistance,
Although some of the physical properties such as tensile strength, surface hardness, and flexibility are excellent, it is difficult to say that the composition has satisfactory softness when judged comprehensively. In addition, in recent years, olefin-based thermoplastic elastomers (TP) have been developed as olefin-based soft resin compositions.
E.) was developed, but it is not only expensive but also has the problem of poor surface gloss of the molded product. In addition, ethylene, propylene, and
Resin blends of block copolymers and high-density polyethylene (HDPE) or ethylene-vinyl acetate copolymers (EVA) have been proposed;
The composition obtained by these methods is -30 to -40℃
There is a problem that impact resistance at very low temperatures is poor. [] Structure of the Invention Based on the above, the present inventors have conducted various searches in order to obtain a resin composition that is not only inexpensive but also has excellent low-temperature impact resistance. is 5 to 30% by weight, and the stiffness (measured based on ASTM D-747)
is 13000Kg/ ^cm2 or less, and "Melt Flow Index" (based on JIS K-6758,
Measured at a temperature of 230℃ and a load of 2.16Kg.
Ethylene-propylene block copolymer with an MFI (hereinafter referred to as "MFI") of 0.5 to 30 g/10 minutes.
(hereinafter referred to as ``block copolymer'') and (B) ``melt index'' (measured based on JIS K-6760, measured at a temperature of 190°C and a load of 2.16 kg, hereinafter referred to as ``MI'') is 0.5~40
g/10 min and a density measured based on JIS K-6760 of 0.910 to 0.925 g/cm ³ Straight chain having short chain branches of ethylene and α-olefin having at most 12 carbon atoms This is a composition obtained by mixing a block copolymer (hereinafter referred to as "ethylene-based linear copolymer"), and the proportion of the block copolymer in the composition is 1.
The resin composition, which is characterized by a content of ~99% by weight, not only has excellent low-temperature impact resistance, but also
It was discovered that it can be obtained at a relatively low price, and the present invention was achieved. [] Effects of the Invention The composition obtained by the present invention can not only be produced at a relatively low cost, but also has excellent physical properties as described below. (1) Excellent impact resistance at low temperatures (-40℃). (2) The surface of the molded product has good gloss and hardness. (3) Excellent heat resistance and flexibility. (4) Since moldability is good, molded products with complex shapes can be manufactured. (5) Good appearance with low molding shrinkage and few sink marks. (6) It also has excellent weather resistance. The composition obtained by the present invention not only can be produced at a relatively low cost, but also has the above-mentioned good physical properties, so it is expected to be used in a wide variety of fields. However, typical uses are shown below. (1) Automotive parts such as bumper faces, bumper corners, bumper sight shields, mat guards, and ducts (2) Soft parts such as hoses, tubes, and grips [] Detailed description of the invention (A) Block copolymers used in the present invention The block copolymer used is a block copolymer of ethylene and propylene, and the ethylene content thereof is 5 to 30% by weight, preferably 10 to 30% by weight, and particularly preferably 10 to 25% by weight. If the ethylene content is less than 5% by weight, the resulting composition will have poor low-temperature impact resistance and flexibility. On the other hand, if it exceeds 30% by weight, it is difficult to produce this block copolymer. Also, MFI is 0.5 to 30g/10 minutes, and 1.0
~20g/10 minutes is preferable, especially 3.0~10
g/10 minutes is preferred. If the MFI is less than 0.5 g/10 minutes, the moldability of the composition will be poor. On the other hand, 30g/
If the heating time exceeds 10 minutes, the resulting composition will have low low-temperature impact resistance, which is not preferable. Further, the stiffness is 13,000 Kg/cm ² or less, preferably 11,000 Kg/cm ² or less, and particularly preferably 6,000 to 11,000 Kg/cm ² . If the stiffness exceeds 13000 Kg/cm ² , the resulting composition will lack flexibility. (B) Ethylene-based linear copolymer The ethylene-based linear copolymer used in the present invention is a copolymer of ethylene and α-olefin. MI of the ethylene-based linear copolymer
is 0.5 to 40 g/10 minutes, preferably 1.0 to 30 g/10 minutes, particularly preferably 4.0 to 20 g/10 minutes.
The MI of the ethylene linear copolymer is 0.5g/
If the time is less than 10 minutes, moldability (especially injection molding) will be poor. On the other hand, if it exceeds 40 g/10 minutes, it is not preferable because impact resistance is low. Further, the density of the ethylene-based linear copolymer is 0.910 to 0.925 g/cm ³ . The density of this ethylene-based linear copolymer is
If it is less than 0.910 g/cm ³ , the rigidity is insufficient. On the other hand, if it exceeds 0.925 g/cm ³ , it is unsuitable because the rigidity is high and the flexibility is insufficient. The α-olefin used in the production of the ethylene-based linear copolymer is an α-olefin having at most 12 carbon atoms, and typical examples include propylene, butene-1, hexene-1, and 4-methylpentene. -1 and octene-1. The copolymerization ratio of the α-olefin in this copolymer is usually 1.0 to 18% by weight. The short chain branch in this ethylene-based linear copolymer refers to a branch that is sufficiently short compared to the main chain, and has, for example, less than 15 carbon atoms.
On the other hand, a long chain branch means a branch having a length sufficiently comparable to the main chain, for example, having 15 or more carbon atoms. These block copolymers and ethylene-based linear copolymers can be obtained by copolymerizing ethylene and propylene or ethylene and the above-mentioned α-olefin using a so-called Ziegler catalyst or a Phillips catalyst. . Ziegler's catalyst is a transition metal compound (for example, a halogen-containing compound of titanium) or a carrier for the transition metal compound (for example, a magnesium-containing compound, a compound obtained by treating the magnesium-containing compound with an electron-donating organic compound). It is obtained from a so-called carrier-supported solid catalyst component obtained by supporting the catalyst component on a solid catalyst and an organoaluminum compound. Also,
Phillips catalyst is a carrier-supported catalyst obtained by supporting a chromium or molybdenum oxide or a compound of these oxides and zirconium on a carrier (for example, silica, silica-alumina), or a carrier-supported catalyst and an organic metal. It is obtained from a compound. The above catalysts are merely typical Ziegler catalysts and Phillips catalysts, and other known catalysts may also be used. The method for producing this copolymer is also a well-known method. (C) Composition ratio (mixing ratio) The composition ratio (content ratio) of the block copolymer in the composition obtained by the present invention is 1 to 99% by weight, preferably 30 to 70% by weight, and especially
40-60% by weight is preferred. If the content of the block copolymer in the composition is less than 1% by weight, the heat resistance will be poor. On the other hand, if it exceeds 99% by weight,
Low low temperature impact resistance. (D) Mixing method In producing the composition of the present invention, it can be obtained by first uniformly mixing the propylene-based copolymer and the ethylene-based linear copolymer. Depending on the purpose, anti-aging agents, antioxidants, ultraviolet absorbers, plasticizers, fillers, lubricants, flame retardants, and antistatic agents that are commonly used in olefin polymers mainly composed of ethylene and/or propylene. Additives such as colorants and colorants may also be added to the copolymer to the extent that the above-mentioned properties of the copolymer are not substantially impaired. Mixing methods include dry blending using a mixer such as a Henschel mixer, which is commonly used in the olefin resin industry, and melt kneading using a mixer such as a Banbury mixer, kneader, roll mill, and screw extruder. In this case, a more uniform composition can be obtained by dry blending or melt-kneading the resulting composition (mixture) in advance and then melt-kneading the resulting composition (mixture). Furthermore, a masterbatch is prepared by mixing a part of the ethylene linear copolymer and block copolymer, which are the components of the composition, or these and the above-mentioned additives, and other compositions are added to this masterbatch. They may be mixed to produce the composition used to produce the shock absorber of the present invention. In these cases, it is generally melt-kneaded and then formed into pellets.
It is used for the molding described later. (E) Molding methods, etc. To produce various molded products using the composition of the present invention, molding methods commonly used in the field of commonly used ethylene polymers and propylene polymers can be applied. do it. Examples of the molding method include injection molding, extrusion molding, and compression molding. In order to produce various molded products using these molding methods, it is necessary to conduct the molding at a temperature higher than the melting point of the linear ethylene copolymer and block copolymer used. Of course, the coalescence must be carried out at a temperature below that at which thermal degradation occurs. From the above, the molding temperature is 130~
The temperature is 300℃. The resin composition of the present invention is highly flexible, and includes conventionally used polyurethane (RIM molded) TPE and propylene resin.
Rubber whose main components are ethylene and propylene,
It can replace soft resins typified by blends consisting of ethylene-vinyl acetate copolymer and/or low-density polyethylene having long chain branches, and is suitable for the above-mentioned uses. Physically, it has excellent heat resistance and low-temperature impact resistance, and has superior heat resistance and low-temperature impact resistance.
Compared to E., it has a significantly higher gloss, no flow marks, etc., and has a good appearance. Furthermore, it is characterized by not being sticky like the blends described above and being inexpensive. [] Examples and Comparative Examples The present invention will be explained in more detail below using Examples. In addition, in the Examples and Comparative Examples, the tensile test was performed based on JIS K-6301 at a tensile speed of 200 mm/min. Further, the Dupont impact strength was measured as follows immediately after immersing the flat plate (sample) used in the measurement of the molding shrinkage rate (described later) in a dry ice-methyl alcohol solution (-40°C). Steel cylinder (thickness 2 mm, diameter 46
mm), a 2 kg load weight (tip radius 1/2 inch) was dropped onto the sample from a height of 150 cm, and the presence or absence of cracks was observed. Furthermore, the surface hardness (Shoer D) was measured based on ASTM D-2240. Moreover, gloss was measured based on JIS 2-8741. Furthermore, the heat distortion temperature is ASTM D-648.
Measured based on. The molding shrinkage rate was determined using an injection molding machine (manufactured by Toshiba Machine Co., Ltd., product name IS-80A), with a cylinder temperature of 230°C, injection pressure, and primary pressure of 60~60°C.
75Kg/cm ² , secondary pressure 50-55Kg/cm ² , injection time 12
A flat plate having a thickness of 2 mm and a size of 110 x 150 mm was injection molded under conditions of a cooling time of 20 seconds and a mold temperature of 50°C. At this time, the molding shrinkage rates in the M direction and the T direction were measured. The thermal sagging property was measured by cutting out a specimen with a width of 1/2 inch, a length of 5 inches, and a thickness of 2.0 mm from the molded piece used to measure the molding shrinkage rate.
One end was fixed, and the amount of deformation of the 100 mm long tip was measured after 30 minutes at a temperature of 80°C. Example 1 Ethylene co-content is 16.2 as a block polymer
70% by weight of ethylene-propylene block copolymer [MFI 6.9g/10 min, hereinafter referred to as "polymer (A)"] and ethylene and butene-1 as ethylene-based linear copolymer. A copolymer that is essentially linearly randomly copolymerized [density 0.920g/
cm ³ , MI7.0g/10 minutes, hereinafter referred to as "polymer (B)"]
30 parts by weight were previously dry blended for 5 minutes using a Henschel mixer. The resulting mixture was placed in an extruder (diameter 65 mm) set at a temperature of 220°C.
Pellets were produced using 5 of these pellets
Examples 2 to 5 and Comparative Examples 1 to 8, in which test pieces were created using an injection molding machine of 100 oz. Polymer (A) and ethylene-based linear copolymer used as the block copolymer in Example 1 Dry blending was carried out in the same manner as in Example 1, except that the blending amount of the polymer (B) was changed as shown in Table 1. Pellets were prepared from each of the obtained mixtures under the same conditions as in Example 1 (Examples 2 and 3). Instead of the polymer (A) and polymer (B) used in Example 1, a copolymer in which ethylene and octene-1 were copolymerized in a substantially linear random manner [density 0.916 g/cm ³ , MI15g/10min, below polymer
(C)'' (Example 4)], a copolymer in which ethylene and hexene-1 were copolymerized in a substantially linear random manner [density 0.917 g/cm ³ , MI 10 g/10 min,
Hereinafter referred to as "Polymer (D)" (Example 5)], ethylene-propylene copolymer rubber [ethylene content 70% by weight, MI 0.8 g/10 min, hereinafter referred to as "Polymer (E)",
(Comparative Example 3)], ethylene-vinyl acetate copolymer [vinyl acetate content 15% by weight, MI 2.1 g/10 min, hereinafter referred to as "polymer (F)". (Comparative Example 4)], low-density polyethylene with long chain branches obtained by homopolymerizing ethylene by a high-pressure method [density
0.916g/cm ³ , MI4.1g/10min, hereinafter "polymer (G)"
(Comparative Example 5)] and ethylene and butene.
Copolymer obtained by substantially linear copolymerization with 1 [density 0.960 g/cm ³ , MI 4.9
g/10 min, hereinafter referred to as "polymer (H)" (Comparative Example 6)] were changed as shown in Table 1 (Table 1 shows the blending amount of each polymer). Dry blending was performed in the same manner as in Example 1. Pellets were prepared from each of the obtained mixtures under the same conditions as in Example 1. Instead of the polymer (A) used as the block copolymer in Example 1, a propylene homopolymer (MFI 8.2 g/10 min, hereinafter referred to as "polymer (J)" obtained by homopolymerizing propylene was used. Polymer (J) and Polymer (B) were dry blended in the same manner as in Example 1 at the blending amounts shown in Table 1. Pellets were prepared from the resulting mixture under the same conditions as in Example 1 (Comparative Example 7). Pellets containing only polymer (A) (Comparative Example 1), polymer
Pellets containing only (B) (Comparative Example 2), pellets containing only polymer (H) (Comparative Example 8), and the respective mixed pellets obtained as above were used to produce specimens for measuring each physical property. Example 1 was similarly molded using an injection molding machine (in Comparative Example 3, the molded product was sticky like rubber, and in Comparative Example 4, a considerable odor was generated during molding). The physical properties of each specimen obtained were measured. The results of each physical property obtained and the MFI of each pellet are shown in Table 2.

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[Table] From the results of the above Examples and Comparative Examples, the composition obtained by the present invention has excellent impact resistance at low temperatures, good heat resistance and flexibility, low mold shrinkage rate, It is clear that it can be molded into various shapes and used in a wide variety of fields, since it has few sink marks and has excellent gloss and hardness on the surface of the molded product, as well as good moldability.

Claims (1)

[Claims] 1 (A) The ethylene content is 5 to 30% by weight,
The stiffness is 13000Kg/ ^cm2 or less, and the melt flow index is 0.5 to 30g/cm2.
and (B) ethylene having a melt index of 0.5 to 40 g/10 min and a density of 0.910 to 0.925 g/cm ³ and a carbon number of at most 12. This is a composition obtained by mixing a linear copolymer having short chain branching with α-olefin, and the proportion of the block copolymer in the composition is 1 to 99%.
% by weight.