JP2773894B2 - Resin composition for moisture-permeable film or sheet, moisture-permeable film or sheet, and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a resin composition for a flexible moisture-permeable film or sheet and a moisture-permeable film or sheet which can be used mainly for disposable diapers, plasters, clothing and the like. And its manufacturing method.

(Prior Art) As a moisture-permeable film or sheet, for example, JP-A-58-15538 discloses a linear low-density polyethylene resin and an inorganic filler poorly compatible with the linear low-density polyethylene resin. A porous film or sheet obtained by heating and melting a composition in which a rubber-like substance is blended as a third component, forming the film into a shape of a film, and performing a stretching treatment is disclosed.

(Problems to be Solved by the Invention) However, when the above-described porous film or sheet is stretched in a uniaxial direction, the film or sheet has anisotropy in physical properties, and particularly, the tear strength in the stretching direction. Is extremely reduced.

Further, when the film or sheet is stretched in the biaxial direction, although there is no anisotropy in the physical properties of the film or sheet, there is a problem in stretchability and a problem that the flexibility of the film or sheet is lost. there were.

Furthermore, in order to improve the anisotropy of the physical properties of the film or sheet and the stability of the stretching process, a method of making the film or sheet porous while keeping the stretching ratio as low as possible is usually attempted. There was a problem that the method could not be applied successfully.

Further, in order to improve the anisotropy of the physical properties of the film or sheet and to impart flexibility, a rubber-like substance is added. There was a problem that sheets caused blocking.

(Means for Solving the Problems) The present invention has been made to solve the above problems, and the first invention is to provide (a) a linear ultra-low density polyethylene resin having a density of less than 0.910 g / cm ^3. If, (b) a range which does not exceed five times the weight, density 0.940 g / cm ³ or more high-density polyethylene resin, density 0.910 g / cm ³ or more linear low density polyethylene resins and density 0.910 g / 100 parts by weight of a resin composed of at least one selected from low-density polyethylene resins having a density of at least ³ cm3, (c) 50 to 200 parts by weight of a filler, and (d) 5 to 30 parts by weight of butadiene rubber. A second resin composition for a moisture-permeable film or sheet,
The present invention provides a moisture-permeable film or sheet obtained by stretching a film or sheet formed using the resin composition of the first invention. Using the composition, a film or sheet is formed by an extrusion method, and then the film or sheet is stretched in a uniaxial direction using a roll stretching apparatus, thereby producing a moisture-permeable film or sheet. The above object is achieved.

The linear ultra low density polyethylene resin (a) is a linear copolymer of ethylene and an α-olefin such as butene, hexene, octene, and decene, and has a density of 0.910 g / cm ^3.
Less than. As the commercially available linear ultra low density polyethylene resin (a), for example, "Exelen VL" manufactured by Sumitomo Chemical Co., Ltd. can be mentioned. This linear ultra-low density polyethylene resin is used for improving the tear strength of a moisture-permeable film or sheet and imparting flexibility.

The high-density polyethylene resin (b) is produced by a medium-low pressure method, and has a density of 0.940 g / cm ³ or more. The linear low-density polyethylene resin is a linear copolymer with the above-mentioned α-olefin similarly to the linear ultra-low-density polyethylene resin, and has a density of 0.910 g / cm ³ or more. Further, the low-density polyethylene resin is produced by a high-pressure method, and has a density of 0.910 g / cm ³ or more and less than 0.940 g / cm ³ .

In the composition for a moisture-permeable film or sheet of the present invention, the component (a) and the component (b) are usually composed of (a)
It is used as a mixed resin in which component (b) is mixed at a ratio of 10 to 500 parts by weight, preferably 10 to 300 parts by weight with respect to 100 parts by weight of the component.

(A) A stretched film or sheet using a linear ultra-low density polyethylene resin having a component density of less than 0.910 g / cm ³ is excellent in mechanical strength such as tear strength, stretchability, flexibility, and uniform pores. On the other hand, the stiffness is weak and the workability in a secondary processing (printing, laminating, etc.) apparatus may be deteriorated. However, by blending the above-mentioned component (b), this disadvantage is solved. If the amount of the component (b) exceeds 500 parts by weight, the tear strength of the film or sheet is reduced, the rigidity is increased, and the flexibility is lost.

As the filler of component (c) used in the present invention, inorganic fillers such as calcium carbonate, diatomaceous earth, talc, kaolin, powdered silica, zeolite, mica powder, clay, barium sulfate, titanium oxide, and alumina are suitable. ing. Further, the particle size is 20 μm or less, preferably 5 μm or less. These fillers are generally blended in an amount of 50 to 200 parts by weight, preferably 75 to 150 parts by weight, per 100 parts by weight of the mixed resin, and act to form pores in a film or the like by stretching. If the particle size of these fillers is larger than 20 μm, the pores of the film or sheet formed by the stretching process become large, which is not preferable because it becomes water-permeable rather than staying permeable.

The butadiene rubber of the component (d) used in the present invention comprises:
It is a homopolymer of butadiene or a copolymer of butadiene and another monomer copolymerizable with butadiene, and exhibits rubbery properties, such as polybutadiene, acrylonitrile-butadiene copolymer, and styrene-butadiene. Copolymers and the like are exemplified. The butadiene rubber of the component (d) is added in an amount of 5 to 30 parts by weight, preferably 10 to 20 parts by weight, based on 100 parts by weight of the mixed resin. Butadiene rubber is added to impart flexibility to a film or sheet and to improve the anisotropy of its physical properties.
Butadiene rubber is added in an amount of 5 parts by weight based on 100 parts by weight of the mixed resin.
If the amount is less than 30 parts by weight, the stretchability of the film or sheet is deteriorated.If the amount is more than 30 parts by weight, the film or sheet has flexibility, but it is difficult to perform a porous treatment, and the films or sheets may cause blocking. become. Therefore, the amount of butadiene rubber to be added is limited to the minimum necessary for imparting good stretchability.

In the present invention, excellent mechanical strength, stretchability, and flexibility are exhibited by using, as a base resin, a mixed resin composed of a linear ultra-low density polyethylene (a) and a high density polyethylene resin (b). And the amount of butadiene rubber added can be greatly reduced.

Next, a method for producing the moisture-permeable film or sheet of the present invention will be described with reference to the drawings.

First, a predetermined amount of a filler and butadiene rubber are kneaded with a Banbury mixer 3 and the like, and then a predetermined amount of a linear ultra-low density polyethylene resin (a) and a high density polyethylene resin (b) are sequentially added, After the respective components are made into a uniform kneaded material using the Banbury mixer 3 or the like, the kneaded material is linearly extruded from the pellet extruder 4 and pelletized by the pelletizer 5. From these pellets, a T-die extrusion molding device 6
(Or an inflation extrusion molding apparatus), the film or sheet raw material 1 is formed, and then uniaxially stretched to a predetermined stretching ratio by a stretching molding apparatus 7 to obtain a porous moisture-permeable film or sheet 2.

(Operation) Since the present invention is configured as described above, a mixed resin such as the linear ultra-low density polyethylene resin (a) and the high density polyethylene resin (b) is used to form the tear strength of the moisture-permeable film or sheet. And the like, to enhance mechanical strength, stretchability and flexibility, to form uniform pores, and to reduce the amount of butadiene rubber added.

That is, according to the present invention, compared to the prior art, flexibility is imparted, and excellent mechanical strength such as stretchability and tear strength, and the porous treatment is easily performed, and a moisture-permeable film that does not cause blocking or Sheets can be provided at low cost.

(Example) An example of the present invention will be described below.

Example 1 [1] Production of moisture-permeable film (a) Linear ultra-low density polyethylene resin (MFR2.0, density of 0.1%)
And 900 g / cm ³⁾ 100 parts by weight, mixed resin consisting of (b1) a high density polyethylene resin (density 0.960g / cm ³⁾ 50 parts by weight 100
Parts by weight, (c) 110 parts by weight of calcium carbonate (average particle diameter 1.2 μm) as a filler, and (d) butadiene rubber
The composition containing 11 parts by weight was uniformly kneaded with a Banbury mixer and then pelletized with a pelletizer.

The pellets were extruded with a 50 mmT die extrusion molding apparatus to obtain a 50 μm thick film raw material.

Next, by using a roll stretch molding device,
The film was stretched uniaxially at 80 ° C. to produce a stretched film having a stretching ratio of 2.0.

[2] Measurement of Physical Properties of Stretched Film The following physical properties were measured for the stretched film produced in [1].

-Tensile strength and tensile elongation Measured in the longitudinal direction (stretching direction) and the transverse direction (direction perpendicular to the stretching direction) of the stretched film according to JIS-ZI702.

・ Tear strength Measured in the longitudinal direction according to JIS-P8116.

-Moisture permeability Measured according to JIS-Z0208.

-Yield point strength Measured in the longitudinal direction according to ASTM-D882.

・ Blocking property Two stretched films cut to a size of 1300 × 200 mm were used as test pieces, and the test pieces were sandwiched between two glass plates while the test pieces were stacked and left in a constant temperature bath at 40 ° C. for 24 hours. The test pieces were tested for ease of peeling.

Example 2 (a) 100 parts by weight of a mixed resin composed of 100 parts by weight of the linear ultra-low-density polyethylene resin used in Example 1 and (b1) 300 parts by weight of the high-density polyethylene resin used in Example 1
A uniaxially stretched film was prepared in the same manner as in Example 1 from a composition comprising (c) 110 parts by weight of calcium carbonate and (d) 11 parts by weight of butadiene rubber.

The physical properties of the stretched film were measured in the same manner as in Example 1.

Example 3 A stretched film having a draw ratio of 1.5 was produced by the same composition and method as in Example 1.

The physical properties of the stretched film were measured in the same manner as in Example 1.

Example 4 (d) A uniaxially stretched film was produced by the same composition and method as in Example 1, except that the amount of butadiene rubber was changed to 6 parts by weight.

The physical properties of the stretched film were measured in the same manner as in Example 1.

Comparative Example 1 (b2) To 100 parts by weight of a linear low-density polyethylene resin,
A uniaxially stretched film was prepared from a composition containing (c) 110 parts by weight of calcium carbonate and (d) 11 parts by weight of butadiene rubber in the same manner as in Example 1.

The physical properties of the stretched film were measured in the same manner as in Example 1.

Comparative Example 2 (a) A mixed resin comprising 100 parts by weight of the linear ultra-low density polyethylene resin used in Example 1 and (b1) 600 parts by weight of the high density polyethylene resin was mixed with (c) calcium carbonate 110
A uniaxially stretched film was produced from a composition in which 11 parts by weight of (d) butadiene rubber were blended in the same manner as in Example 1.

The physical properties of the stretched film were measured in the same manner as in Example 1.

Comparative Example 3 (b2) To 100 parts by weight of the linear low-density polyethylene resin,
A uniaxially stretched film was prepared in the same manner as in Example 1 from a composition comprising (c) 110 parts by weight of calcium carbonate and (d) 30 parts by weight of butadiene rubber.

The physical properties of the stretched film were measured in the same manner as in Example 1.

Comparative Example 4 (d) A uniaxially stretched film was produced by the same composition and method as in Comparative Example 3 except that the amount of butadiene rubber was changed to 6 parts by weight.

Comparative Example 5 A uniaxially stretched film having a draw ratio of 1.5 was produced by the same composition and method as in Comparative Example 1.

The physical properties of the stretched film were measured in the same manner as in Example 1.

Table 1 shows the composition (parts by weight), film thickness, stretch ratio and stretchability of each of the above Examples and Comparative Examples, and Table 2 shows their mechanical strength, moisture permeability and blocking properties.

In the following table, the amounts of (c) and (d) are expressed in parts by weight per 100 parts by weight of (a) + (b1) + (b2).状態 indicates a state in which the film can be stretched uniformly, 発 生 indicates a state in which the stretching unevenness is slightly large but the film is not cut during the stretching, and × indicates a state in which the stretching unevenness is large and the film is cut during the stretching.

[Effect of the Invention] Since the moisture-permeable film or sheet of the present invention is constituted as described above, it exhibits excellent stretchability as compared with the conventional method, and can realize uniform porosity at a low stretch ratio.

Furthermore, despite the uniaxial stretching process, anisotropy of physical properties is not exhibited, and excellent balance of physical properties such as tensile strength, tear strength, moisture permeability, water resistance, flexibility, etc., and blocking between films or sheets. Do not wake up.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing one embodiment of the manufacturing process of the present invention. DESCRIPTION OF SYMBOLS 1 ... Film raw material 2, ... Moisture permeable film, 3 ... Banbury mixer, 4 ... Pellet extruder, 5 ... Pelletizer, 6 ... T-die extrusion molding apparatus, 7 ... Roll stretching forming apparatus

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29K 23:00 105: 04 B29L 7:00

Claims (3)

(57) [Claims] (1) a linear ultra-low-density polyethylene resin having a density of less than 0.910 g / cm ³ , and (b) a density of 0.940 g / c in a range not exceeding 5 times its weight.
m ³ or more high-density polyethylene resin, density 0.910 g / cm ³ or more linear low density polyethylene resins and density 0.910 g / c
and m ³ or more low density made of one or more selected from polyethylene resin 100 parts by weight of the resin, and (c) filler 50 to 200 parts by weight, were blended and (d) butadiene rubber 5-30 parts by weight A resin composition for a moisture-permeable film or sheet. 2. A moisture-permeable film or sheet obtained by stretching a film or sheet formed using the resin composition according to claim 1. 3. A film or sheet is formed by an extrusion method using the resin composition according to claim 1, and then the film or sheet is uniaxially stretched using a roll stretching apparatus. A method for producing a moisture-permeable film or sheet.