JP2003041070A - Film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide films having excellent balance of flexibility, heat resistance and transparency. SOLUTION: The films are made of a resin composition comprising (A) an ethylene-vinyl acetate copolymer and (B) an isotactic propylene polymer. The weight ratio of the components (A) to (B) is regulated so as to be (95:5)-(40:60), and the absolute value of the difference of the refractive indexes of the components (A) and (B) is <=0.05. Although a film and a sheet are distinguished by the thickness, the film contains sheet.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to films comprising a resin composition containing an ethylene-vinyl acetate copolymer and an isotactic propylene polymer.

[0002]

2. Description of the Related Art Films and sheets made of polyvinyl chloride are inexpensive and easy to mold. Therefore, skin leather for automobile interior, decorative sheet for construction, decorative sheet for steel plate, wrap film, infusion bag, wallpaper, agriculture. Widely used as film for film. However, it has been pointed out that polyvinyl chloride emits toxic dioxin and hydrogen chloride gas when incinerated, and has become a major social problem in recent years. Examples of the film similar to the soft polyvinyl chloride film include a film made of an ethylene-vinyl acetate copolymer, but it cannot be said that the film has sufficient heat resistance. On the other hand, a film made of an isotactic propylene polymer has excellent heat resistance, but is not sufficiently flexible.

[0003]

Therefore, it was tried to produce a film or sheet using a resin composition comprising an ethylene-vinyl acetate copolymer and an isotactic propylene polymer. In some cases, the transparency was not good, and the transparency was sometimes deteriorated. Under such circumstances, an object of the present invention is to provide films having an excellent balance of flexibility, heat resistance and transparency.

[0004]

The present invention contains an ethylene-vinyl acetate copolymer (A) and an isotactic propylene polymer (B), and the weight ratio of the (A) to the (B). Is 95: 5 to 40:60, and the above problems are solved by films made of a resin composition in which the absolute value of the difference in refractive index between the (A) and the (B) is 0.005 or less. It is a thing. Although the film and the sheet are distinguished by the thickness, they are collectively referred to as films in the present invention.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The ethylene-vinyl acetate copolymer (A) used in the present invention is a polymer obtained by copolymerizing ethylene and vinyl acetate. For example, ethylene and vinyl acetate are mixed at a pressure of 1000. It can be obtained by polymerizing in the presence of a radical polymerization initiator under conditions of -3500 kg / cm ² and temperature of 160-350 ° C, and further in the presence of a chain transfer agent if necessary.

As the ethylene-vinyl acetate copolymer (A), one having a content of repeating units derived from vinyl acetate of 1 to 30% by weight is usually used, and preferably the content is 3 to 25% by weight. %, And more preferably 5 to 20% by weight. If the content is too small, the transparency of the obtained films will be poor, and conversely, if the content is too large, the heat resistance of the obtained films will be deteriorated. The content of the repeating unit derived from vinyl acetate is JIS K67.
Measure according to 30.

The isotactic propylene polymer (B) used in the present invention means a thermoplastic resin having an isotactic sequence structure obtained by polymerizing propylene, and has 80 or more repeating units derived from propylene. A thermoplastic propylene polymer containing at least mol% is preferable, and a propylene homopolymer, a copolymer of propylene and at least one α-olefin having 2 to 10 carbon atoms (excluding propylene), or More preferred is a copolymer of propylene and at least one other monomer. Ethylene as the α-olefin, 1-
Butene, 4-methyl-1-pentene, 1-hexene, 1
Examples thereof include octene and 1-decene. As another monomer, a conjugated diene (for example, butadiene or isoprene) can be exemplified. Further, examples of the copolymer include a random type and a block type by multistage polymerization.

The isotactic propylene polymer (B) used in the present invention is a random copolymer of propylene and at least one α-olefin having 2 to 10 carbon atoms (excluding propylene). preferable. In such a random copolymer, α other than propylene
The content of repeating units derived from olefins is 5
0 to 1% by weight is preferable, and 30 to 2% by weight is more preferable. When the content is within the above range, the transparency is excellent and it is preferable.

Further, the melt flow rate (MF) of the isotactic propylene polymer (B) used in the present invention is
R) is also not particularly limited, but the MFR measured at 230 ° C. is preferably in the range of 0.1 to 20 g / 10 minutes. The isotactic propylene polymer (B) used in the present invention has a heat of crystal fusion of 30 J /
It is preferably in the range of g to 120 J / g, and 50 J
/ G to 120 J / g is more preferable. If the heat of fusion of the crystals is too low, the heat resistance of the obtained films may decrease.

The above isotactic propylene polymer (B) is produced by a known polymerization method using a known olefin polymerization catalyst, for example, a Ziegler-Natta type catalyst.
It is produced by a slurry polymerization method, a solution polymerization method, a turbulent polymerization method, a gas phase polymerization method, or the like.

The ethylene-vinyl acetate copolymer (A) and isotactic propylene polymer (B) of the present invention
The weight ratio of them in the resin composition containing (A) :( B) = 95: 5 to 40:60. If the amount of the ethylene-vinyl acetate copolymer (A) is too large, the heat resistance of the resulting films will be poor, which is not preferable. Conversely, if the amount of the isotactic propylene polymer (B) is too large, the flexibility of the obtained films will be low. It is not preferable because it is inferior in properties. Preferably the weight ratio is 90:10 to 50:50,
More preferably, it is 80:20 to 60:40.

In the resin composition used in the present invention, the absolute value of the difference in refractive index between the ethylene-vinyl acetate copolymer (A) and the isotactic propylene polymer (B) is 0.005 or less. The absolute value of the difference in refractive index is preferably 0.003 or less. When the absolute value of the difference in the refractive index is within this range, the obtained films have excellent transparency, particularly transparency based on internal haze.

In the resin composition used in the present invention, various additives and fillers such as an antioxidant, a nucleating agent, an ultraviolet absorber, a lubricant, an antiblocking agent, an antistatic agent, and an antifogging agent may be added, if necessary. Agents and the like can be included. Furthermore, other resins may be blended and used within a range not hindering the present invention.

The above ethylene-vinyl acetate copolymer (A)
The method for blending the isotactic propylene polymer (B) with various additives, fillers, and other resins as necessary is not particularly limited, and known methods such as kneader, Banbury mixer, It can be carried out by heating, melting and kneading using a kneader such as a roll or a single-screw or twin-screw extruder. Also, various resin pellets may be dry blended.

The thickness of the films of the present invention is not particularly limited and can be arbitrarily selected. Usually, it is 1 to 2000 μm, preferably 10 to 150
μm, more preferably 20 to 120 μm, and particularly preferably 30 to 100 μm.

The films of the present invention can be obtained by forming a film by a usual method such as an inflation method or a T-die method. The films of the present invention may be multilayer films composed of a plurality of layers, and examples thereof include multilayer films in which at least one layer of the multilayer films is a layer composed of the above resin composition. Such multi-layer films are formed by a method of heat-bonding separately produced films, or by a coextrusion type inflation film molding machine or T-die film molding machine of, for example, 2 types 2 layers or 2 types 3 layers. It is possible to manufacture. It is also possible to laminate the other resin layer on any one of the resin layers formed by a known method such as extrusion lamination.

[0017]

EXAMPLES The present invention will be described below based on examples.
The present invention is not limited to these examples as long as the gist thereof is not exceeded. First, a method for measuring physical property values in the following examples and comparative examples will be described.

(1) Content of repeating unit derived from vinyl acetate (unit:% by weight): Measured according to JIS K6730.

(2) MFR (unit: g / 10 minutes): JI
According to SK7210, the propylene polymer was measured according to the condition 14 in Table 1.

(3) Content of Repeating Units Derived from α-Olefin in Propylene Polymer ¹³ C-by the method described in pages 615 to 619 of Handbook for Polymer Analysis (1995, Kinokuniya Bookstore). The measurement was performed by the NMR method.

(4) 1% SM (unit: MPa): A test piece with a length of 12 cm and a width of 2 cm was cut out in the film forming direction (MD direction), and a distance between chucks of 6 cm was set in a tensile tester.
Then, the stress when the sample was attached at a speed of 5 mm / min and stretched by 1% was obtained, and 1% SM was obtained by the following formula. The larger this value, the better the rigidity. 1% SM = 100 × (stress) ÷ (cross-sectional area)

(5) Thermal expansion coefficient (unit:%): A test piece having a length of 10 cm and a width of 10 cm was cut out at 70 ° C. so that the length and width of the test piece were parallel to the MD and TD directions of the film, respectively. The sample was placed in warm water adjusted to 1, and after 1 minute, the lateral length L (cm) of the test piece was measured in warm water, and the coefficient of thermal expansion was determined by the following formula. The smaller this value, the better the heat resistance. Thermal expansion coefficient = (L-10) / 10 × 100

(6) Haze (unit:%) The haze was measured according to the method specified in ASTM D1003. The smaller this value is, the better the transparency is. Further, in order to suppress light scattering on the film surface irregularities, dimethyl phthalate (refractive index 1.
51) was satisfied and the film was submerged in this cell, and the internal haze was measured.

Example 1 As an ethylene polymer resin (A), Evatate H2081 manufactured by Sumitomo Chemical Co., Ltd. [Ethylene-vinyl acetate copolymer, MFR = 2 g / 10 min, a repeating unit derived from vinyl acetate] Content = 16% by weight, refractive index = 1.498], and Noblene S131 manufactured by Sumitomo Chemical Co., Ltd. as a propylene polymer resin (B)
[Propylene-ethylene random copolymer, MFR = 1
g / 10 min, content of repeating unit derived from ethylene = 5% by weight, refractive index = 1.497] and 90:10
To prepare a resin composition by dry blending in a weight ratio of
This was supplied to an inflation film molding machine manufactured by Placo Co., Ltd. equipped with an inflation die having a die diameter of 125 mm and a die lip of 2.0 mm, and a die temperature of 190 ° C.
A film having a thickness of 50 μm was manufactured by inflation molding at a blow ratio of 1.8 and a take-up speed of 10 m / min. Table 1 shows various characteristic values of the obtained film.

[Example 2] In Example 1, the ethylene polymer resin (A) (Evatate H manufactured by Sumitomo Chemical Co., Ltd.) was used.
2081) and the propylene polymer resin (B) (Sumitomo Chemical Co., Ltd. Nobrene S131) in a weight ratio of 70: 3.
The thickness was 50 μm in the same manner as in Example 1 except that the thickness was changed to 0.
m film was produced. Table 1 shows various characteristic values of the obtained film.

Example 3 In Example 1, an ethylene polymer resin (A) (Evatate H manufactured by Sumitomo Chemical Co., Ltd.) was used.
2081) and the propylene polymer resin (B) (Sumitomo Chemical Co., Ltd. Nobrene S131) in a weight ratio of 50: 5.
The thickness was 50 μm in the same manner as in Example 1 except that the thickness was changed to 0.
m film was produced. Table 1 shows various characteristic values of the obtained film.

[Example 4] In Example 2, the propylene polymer resin (B) was replaced by Noblene FS2011DG2 [Propylene homopolymer, MFR = manufactured by Sumitomo Chemical Co., Ltd.].
A film having a thickness of 50 μm was produced in the same manner as in Example 2, except that the refractive index was changed to 1 g / 10 minutes, the refractive index = 1.500, and the die temperature was changed to 200 ° C. Table 1 shows various characteristic values of the obtained film.

[0028]

[Table 1] ※Absolute value

[0029]

[Table 2]

The internal haze of the films obtained in these examples has a very small value and can be highly transparent films. If transparency is deteriorated due to external haze,
It can be improved by changing the processing conditions or forming a laminated film with other resin by the coextrusion method.

[0031]

As described in detail above, according to the present invention,
Provided are films having an excellent balance of flexibility, heat resistance and transparency.

Claims (3)

[Claims] 1. An ethylene-vinyl acetate copolymer (A) and an isotactic propylene polymer (B) are contained,
The weight ratio of the (A) to the (B) is 95: 5 to 40: 6.
Films made of a resin composition having a refractive index difference of 0 and an absolute value of the difference in refractive index between the (A) and the (B) of 0.005 or less. 2. The propylene polymer (B) is a random copolymer of propylene and at least one α-olefin having 2 to 10 carbon atoms (excluding propylene). Films. 3. The ethylene-vinyl acetate copolymer (A)
Is an ethylene-vinyl acetate copolymer having a content of repeating units derived from vinyl acetate of 3 to 25% by weight, and the films according to claim 1 or 2.