JP2000336216A - Ethylene copolymer composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ethylene copolymer composition flexible and excellent in strengths, moldability and heat resistance. SOLUTION: There is provided a composition comprising a polyethylene having a density of 900-930 kg/m3 and a melt flow rate at a load of 2,160 g of 0.1-15 g/10 min and an ethylene-unsaturated ester copolymer containing 5-49 wt.% of an unsaturated ester, which composition has an unsaturated ester content in the range of 10-20 wt.% and a melt flow rate at a load of 2,160 g in the range of 0.1-15 g/10 min and the copolymer is compounded in an amount of 75-20 pts.wt. relative to 25-80 pts.wt. of the polyethylene (provided that when the ethylene-unsaturated ester copolymer is solely composed of an ethylene-vinyl acetate copolymer and a polyethylene employed is one having a Vicat softening point of lower than 95 deg.C, the copolymer is compounded in an amount of 45-20 pts.wt. relative to 55-80 pts.wt. of the polyethylene.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ethylene copolymer composition which is flexible and has excellent strength, moldability and heat resistance.

[0002]

2. Description of the Related Art Ethylene / unsaturated ester copolymers represented by ethylene / vinyl acetate copolymers have excellent flexibility, impact resistance, weather resistance, filler loading properties, etc. and are widely used as molding materials. However, there is a problem in heat resistance. For example, in a copolymer containing 10% by weight or more of an unsaturated ester, the copolymer melts at 100 ° C. or less.
The field of use was limited. Polyethylene, especially L
Linear polyethylene, known as LDPE, has a higher melting point and better heat resistance than the above copolymers, but has the drawback of being hard and poor in filler loading and cold resistance.

Attempts have been made to blend both of these for a long time, but it has not been easy to obtain a composition having a good balance of heat resistance, flexibility, moldability, strength and the like.
For example, Japanese Patent Publication No. 35-7286 proposes a blend of polyethylene and an ethylene / lower alkyl acrylate copolymer, which provides a composition excellent in stress crack resistance, gloss and toughness without delamination. For that purpose, no specific formulation for obtaining a composition having a good balance between heat resistance and flexibility is taught. See also
JP-A-9-66437 proposes a film composition comprising an ethylene-ethyl acrylate copolymer and LLDPE. However, since a composition having excellent sealing properties, impact resistance, and the like is demanded, a similar composition is required. No specific formulation for obtaining a composition having a good balance between heat resistance and flexibility is taught.

[0004]

According to the study of the present inventors, in a blend system of an ethylene / unsaturated ester copolymer and polyethylene, flexibility is often sacrificed in order to increase heat resistance. Thus, it was not easy to obtain a well-balanced composition, for example, in the case of seeking flexibility, such as sacrificing heat resistance and tensile strength. In such a blended system, there is also a problem that when exposed to a high-temperature atmosphere for a long time, the strength is reduced.

[0005] The inventors of the present invention have sought a compounding system having heat resistance so as not to be melted even at 100 ° C, and having sufficient flexibility and high strength. At the same time, a blending system capable of suppressing heat aging as much as possible was also studied. As a result, as described later, it has been found that a composition having desired properties can be obtained by strictly selecting the types and mixing ratios of polyethylene and an ethylene / unsaturated ester copolymer. Accordingly, an object of the present invention is to provide an ethylene copolymer composition having high strength and excellent heat resistance, flexibility, and processability.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a density of 900 is provided.
９930 kg / m ³ , melt flow rate (190 ° C.,
2160 g load, the same shall apply hereinafter) is a composition comprising polyethylene of 0.1 to 15 g / 10 min and an ethylene / vinyl acetate copolymer having a vinyl acetate content of 5 to 49% by weight, wherein acetic acid in the composition is The vinyl content is in the range of 10 to 20% by weight and the melt flow rate is 0.1 to
In the case where a polyethylene having a Vicat softening point of less than 95 ° C. is used as the polyethylene, the above copolymer is used in an amount of 45 to 80 parts by weight of polyethylene.
When a polyethylene having a Vicat softening point of 95 ° C. or higher is used as the polyethylene, the copolymer is used in an amount of 75 to 20 parts by weight based on 25 to 80 parts by weight of the polyethylene.
The present invention relates to an ethylene copolymer composition characterized by being blended in parts by weight.

[0007] The present invention also provides a density of 900 to 930 kg.
/ M ³ , polyethylene having a melt flow rate of 0.1 to 15 g / 10 min and unsaturated ester content of 5 to 49% by weight
Wherein the content of the unsaturated ester in the composition is in the range of 10 to 20% by weight, at least a part of which is from the unsaturated carboxylic acid ester. The copolymer has a melt flow rate in the range of 0.1 to 15 g / 10 min.
The present invention relates to an ethylene copolymer composition which is blended at a ratio of 20 parts by weight.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention has a density of 900-930
kg / m ³ , melt flow rate is 0.1 to 15 g / 1
A composition comprising polyethylene for 0 minutes and an ethylene / unsaturated ester copolymer having an unsaturated ester content of 5 to 49% by weight, wherein an unsaturated ester based on the copolymer is contained in the composition at 10 to 20%. %, And the melt flow rate is 0.1 to 15 g / 10 min. In the first invention, the copolymer is ethylene-vinyl acetate copolymer. In the second invention, an ethylene / unsaturated carboxylic acid ester copolymer is used as at least a part of the copolymer.

The polyethylene used in the present invention is a homopolymer of ethylene or an ethylene / α-olefin copolymer containing ethylene as a main component and having a density of 90.
0 to 930 kg / m ³ , preferably 905 to 920 kg
/ M ³ and the melt flow rate is 0.1 to 15 g
/ 10 minutes, which may be produced by any method. For example, high-pressure process polyethylene obtained by high-pressure radical polymerization, LLDPE obtained in the presence of a multi-site catalyst or a single-site catalyst
An ethylene / α-olefin copolymer known as a polymer can be exemplified. It is not necessary to use a single polyethylene, but a combination of two or more of high-density, medium-density, low-density polyethylene, LLDPE, etc., so that the polyethylene as a whole has a predetermined density and a predetermined melt flow rate. You can also. If the density is larger than the above range, it becomes difficult to obtain a composition having excellent flexibility, and if the density is smaller than the above range, it becomes difficult to obtain a composition having excellent heat resistance. Therefore, neither is preferable.

In order to obtain a composition having excellent heat resistance, polyethylene has a Vicat softening point of 85 to 130.
It is preferable to use one having a melt flow rate of 0.1 to 15 g / 10 min, particularly 0.1 to 5 g in order to obtain a composition having balanced physical properties. It is preferable to use one for / 10 minutes.

As the ethylene / unsaturated ester copolymer, those having an unsaturated ester content of 5 to 49% by weight, preferably 10 to 35% by weight are used alone or in combination of two or more. Unsaturated ester content is 10
In order to make the content of 少 な い 20% by weight, when using one having a low unsaturated ester content, it is inevitably used together with one having a high unsaturated ester content. If the content of the unsaturated ester is less than the above range, it is not preferable because it hardly contributes to imparting flexibility and processability. If the content is too large, the composition becomes sticky, which is not preferable. At least two or more of such copolymers are used, and at least two of them differ in unsaturated ester content by 2% by weight or more, preferably 5 to 15% by weight. 1 of the whole united
When used in an amount of 0% by weight or more, it is preferable because a composition excellent in balance between heat resistance, flexibility and strength and excellent in heat aging resistance can be obtained.

The ethylene / unsaturated ester copolymer also has a melt flow rate of 0.1 to 15 g / 10
It is desirable to use a composition having a heat resistance of 0.1 to 5 g / 10 minutes in order to obtain a composition having good heat resistance. Examples of the unsaturated ester in the ethylene / unsaturated ester copolymer include vinyl esters such as vinyl acetate, methyl acrylate, ethyl acrylate, isopropyl acrylate, and the like.
Examples include unsaturated carboxylic esters such as isobutyl acrylate, n-butyl acrylate, isooctyl acrylate, and methyl methacrylate. Such an ethylene / unsaturated ester copolymer can be produced by radical copolymerization under high temperature and high pressure, similarly to the production of high pressure polyethylene.

When only the ethylene / vinyl acetate copolymer is used as the ethylene / unsaturated ester copolymer in the present invention, it is necessary to adjust the amount of the ethylene / vinyl acetate copolymer in accordance with the Vicat softening point of the polyethylene used. That is, when using a polyethylene having a Vicat softening point of less than 95 ° C. as polyethylene, 55 to 80 parts by weight of polyethylene, preferably 55 to 70 parts by weight, and 45 to 20 parts by weight of ethylene / vinyl acetate copolymer , Preferably 45
It is blended at a ratio of ３０30 parts by weight. When polyethylene having a Vicat softening point of 95 ° C. or higher is used as the polyethylene, 25 to 80 parts by weight of polyethylene, preferably 25 to 80 parts by weight.
7 parts by weight of ethylene-vinyl acetate copolymer
It is used in a proportion of 5 to 20 parts by weight, preferably 75 to 30 parts by weight. If the blending ratio of polyethylene exceeds the above range, it is difficult to obtain a flexible composition, and if the blending ratio is less than the above range, it becomes difficult to obtain a composition having excellent heat resistance.

When only the ethylene / unsaturated carboxylic acid ester copolymer is used as the ethylene / unsaturated ester copolymer, or when the ethylene / unsaturated carboxylic acid ester copolymer and the ethylene / vinyl acetate copolymer are used in combination. In this case, the ethylene / unsaturated ester copolymer is 75 to 20 parts by weight, preferably 75 to 80 parts by weight, preferably 25 to 70 parts by weight, based on 25 to 80 parts by weight of polyethylene.
Used in a proportion of 30 parts by weight. If the blending ratio of polyethylene exceeds the above range, it is difficult to obtain a flexible composition, and if the blending ratio is less than the above range, it becomes difficult to obtain a composition having excellent heat resistance.

The polyethylene and the ethylene / unsaturated ester copolymer preferably have an approximate melt flow rate. For example, the difference in melt flow rate is 5 g / 10 min or less, preferably 4 g / 10 min or less. It is better to be. Also, considering various physical properties, the melt flow rate of both compositions is 0.1 to 1
It is desirable to adjust so as to be in a range of 5 g / 10 minutes, particularly 0.1 to 5 g / 10 minutes.

Various additives can be added to the composition of the present invention, if necessary. Examples of such additives include antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, antistatic agents, lubricants, antiblocking agents, pigments, dyes, crosslinking agents, foaming agents, inorganic fillers, and inorganic fillers. Flame retardants and the like can be added.

According to the present invention, by appropriately selecting the kind and the mixing ratio of the polyethylene and the ethylene / unsaturated ester copolymer, they do not melt at 100 ° C. and have a breaking strength of 22 to 37 MPa, preferably 23 to 37 MPa. ~ 35MPa,
A composition excellent in heat resistance, strength, flexibility and workability such as a Shore D hardness of 35 to 45, preferably 36 to 44 can be obtained.

[0018]

Next, the present invention will be described in more detail by way of examples. In addition, the raw materials and various physical property evaluation methods used in the examples are as follows.

1. Raw materials (1) Polyethylene

[Table 1] *: Single site catalyst LLDPE **: LLDPE

(2) Ethylene / unsaturated ester copolymer

[Table 2]

(3) Antioxidant Ir1010 (trade name: Irganox 1010, manufactured by Ciba Specialty Chemicals)

2. Physical properties test method (1) Tensile properties: JIS K6760 Specimen: JIS K6301 No. 3 dumbbell 1 mm thickness Heat aging: Heating conditions of JIS C3005 (100 ° C. ×
(48 hours) (2) Melt flow rate (MFR): JIS K67
Conforms to 60 190 ° C, 2160g load (3) Flexural rigidity: conforms to JIS K7106 (4) Hardness: conforms to JIS K7215 (5) Vicat softening point: conforms to JIS K6730

Examples 1 to 8 and Comparative Examples 1 to 9 The respective raw materials were blended at the blending ratios shown in Table 3 (Example) and Table 4 (Comparative Example), and melt kneading was performed using a 40 mmφ single screw extruder. To prepare a polymer composition. The workability (MFR) of the obtained composition was examined, and sheets having a thickness of 1 mm and 3 mm were prepared by press molding, and tensile properties, hardness, heat resistance (heat aging), and the like were evaluated. The results are shown in Tables 3 and 4.

[0024]

[Table 3]

[0025]

[Table 4]

As is clear from Tables 3 and 4, when Examples 1 to 5 and Comparative Examples 1 to 7 are compared, in the composition of polyethylene and ethylene / vinyl acetate copolymer, the type and type of polyethylene used By appropriately selecting the compounding amount, the heat resistance becomes extremely good despite the toughness, the moldability, and the flexibility are excellent, and a composition having excellent properties that cannot be obtained by each polymer alone is obtained. You can see that. In particular, those using two kinds of ethylene / vinyl acetate copolymers (Examples 1 and 2) are more excellent in heat aging resistance than those using only one kind (Examples 3 to 5). On the other hand, if the selection and the mixing ratio of polyethylene are not appropriate, those having good flexibility and heat resistance cannot be obtained (Comparative Examples 1 to 4).

As is clear from the comparison between Examples 6 to 8 and Comparative Examples 8 to 9, when the ethylene / ethyl acrylate copolymer is used as at least a part of the ethylene / unsaturated ester copolymer. Has the same tendency,
There is an advantage that a composition having desired physical properties can be obtained even when the blending amount of polyethylene (PE-2) having a low Vicat softening point is relatively small (Examples 6, 8).

[0028]

According to the present invention, a high-strength ethylene copolymer composition having excellent moldability, flexibility and heat resistance can be provided. Taking advantage of such characteristics, it can be used as various molded products by various molding methods such as extrusion molding, injection molding, compression molding, hollow molding, and foam molding. For example, civil engineering fields such as artificial turf, mats, waterproof sheets, tunnel sheets, roofing, etc., pipe applications such as hoses and tubes, home appliances such as packing and vibration damping sheets, carpet backing materials, door panel prevention sheets, mudguards It can be used in various fields such as automotive parts such as malls, building materials such as furniture, flooring materials, foam sheets, etc., and cables such as communication cables, electric power cables, and shrink tubing containing a flame retardant.

Claims (5)

[Claims] (1) a density of 900 to 930 kg / m ³ , 19
A composition comprising polyethylene having a melt flow rate of 0.1 to 15 g / 10 min at 0 ° C. and a load of 2160 g and an ethylene / vinyl acetate copolymer having a vinyl acetate content of 5 to 49% by weight. Vinyl acetate content in the range of 10 to 20% by weight and 190
C. and a melt flow rate at a load of 2160 g of 0.
In the case where polyethylene having a Vicat softening point of less than 95 ° C. is used, the above copolymer is added to 55 to 80 parts by weight of polyethylene.
In the case of using a polyethylene having a Vicat softening point of 95 ° C. or higher, the above copolymer is used in an amount of 75 to 20 parts by weight based on 25 to 80 parts by weight of polyethylene.
An ethylene copolymer composition, which is blended at a ratio of 20 parts by weight. 2. An ethylene / vinyl acetate copolymer comprising at least two types, at least one of which is:
The melt flow rate at 190 ° C. under a load of 2160 g is in the range of 0.1 to 15 g / 10 minutes, and at least two of them have a vinyl acetate content of 2% by weight relative to each other.
2. The ethylene copolymer composition according to claim 1, which is different from the above. 3. A density of 900 to 930 kg / m ³ , 19
A composition comprising a polyethylene having a melt flow rate of 0.1 to 15 g / 10 min at 0 ° C. and a load of 2160 g and an ethylene / unsaturated ester copolymer having an unsaturated ester content of 5 to 49% by weight. The content of the unsaturated ester in the composition is in the range of 10 to 20% by weight, at least a part of which is composed of unsaturated carboxylic acid ester, and the melt flow rate at 190 ° C. under a load of 2160 g is 0.1 to 15 g / 10. Of the above copolymer in 75 to 2 parts by weight and 25 to 80 parts by weight of polyethylene.
An ethylene copolymer composition, which is blended at a ratio of 0 parts by weight. 4. An ethylene / unsaturated ester copolymer comprising at least two kinds, and at least one of them has a melt flow rate at 190 ° C. under a load of 2160 g within a range of 0.1 to 15 g / 10 minutes. 4. The ethylene copolymer composition according to claim 3, wherein at least two of them have different unsaturated ester contents by at least 2% by weight. 5. It does not melt at 100 ° C. and has a breaking strength of 22
The ethylene copolymer composition according to any one of claims 1 to 4, wherein the Shore D hardness is in the range of 35 to 45 MPa.