JPH0716939A - Porous film or sheet - Google Patents

Abstract

PURPOSE:To obtain a porous film or sheet good in longitudinal and lateral strength balance and tear strength and free from stretching irregularity by combining a specific amt. of a polybutylene resin with a polyethylene resin. CONSTITUTION:A porous film or sheet is formed from a resin compsn. consisting of 99-20 pts.wt. of a polyethylene resin (a), 1-80 pts.wt. of a polybutene resin (b), 100-400 pts.wt. of a filler with respect to 100 pts.wt. of the sum total amt. of the resins (a), (b) and 1-100 pts.wt. of a plasticizer with respect to 100 pts.wt. of the sum total amt. of the resins (a), (b). The density of the polyethylene resin is 0.910-0.965g/cm<3> and the melt index thereof is 20g/10min or less and the density of the polybutene resin is 0.93g/cm<3> or less.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to porous films or sheets. Specifically, a polybutene resin formed from a resin composition in which linear polyethylene or the like is blended at a certain ratio, has a good longitudinal and lateral strength balance and tear strength,
Moreover, the present invention relates to a porous film or sheet having no uneven drawing of the film.

[0002]

2. Description of the Related Art In recent years, porous synthetic resin films having fine pores that allow water vapor and other gases to pass through, but not water droplets, have come to be used in the fields of clothing and medicine. This has the effect of preventing stuffiness and preventing the liquid from leaking to the outside. Specifically, it is often used for diapers, raincoats and the like.

A typical method for producing the porous film or sheet having air permeability is to mix a synthetic resin with an inorganic filler such as calcium carbonate, talc, or clay to form a film, which is then stretched to form a fine film. Examples include a method of causing a crack. The porous film or sheet thus obtained has a problem in anisotropy, particularly in physical properties of balance between tensile strength in the longitudinal direction (stretching direction) and tensile strength in the transverse direction.

Some of the present inventors have solved the above problems by first molding and stretching a composition comprising a specific amount of linear polyethylene, branched low-density polyethylene, a radical generator and a filler. A method for producing a porous film or sheet having a high temperature is proposed (USP 5,015,52).
1).

[0005]

DISCLOSURE OF THE INVENTION The present inventors have further earnestly studied to provide a film or sheet having improved balance between tensile strength in the longitudinal direction and transverse direction and tear strength. For example, this type of porous film or sheet is used as a diaper or an exterior material for sanitary items such as sanitary items by utilizing its breathability, but the strength of the adhesive portion of the fixing tape is There are problems such as not being sufficient, and improvement of this point has been desired.

[0006]

Means for Solving the Problems As a result of intensive studies for achieving the above-mentioned object, the present inventors have found that the above object can be achieved by combining a specific amount of polybutylene resin with polyethylene resin as a resin component. The present invention has been completed after confirming that it can be achieved. That is, the gist of the present invention is (a) a polyethylene resin 99 to 20 parts by weight, (b) a polybutene resin 1 to 80 parts by weight, and a filler 100 to 400 parts by weight with respect to a total amount of 100 parts by weight of (a) and (b). Parts and plasticizer 1-10
It exists in a porous film or sheet formed from a resin composition containing 0 part by weight.

The present invention will be described in detail below. The polyethylene resin (a) in the present invention has a density of usually 0.910 to 0.965 g / cm ³ , preferably 0.
A melt index of 910 to 0.945 g / cm ³ and a melt index of 20 g / 10 minutes or less, preferably 10 g / 10 minutes or less, and particularly preferably 0.01 to 5 g / 10 minutes is used. For example, the density is 0.91 to 0.95 g / c
linear m ³ low-density polyethylene and density of 0.965 g /
Examples include high-density polyethylene having a size of ³ cm ³ or less, and a mixture thereof.

The linear low density polyethylene is a copolymer of ethylene and other α-olefin, and is different from the branched low density polyethylene produced by the conventional high pressure method. The linear low-density polyethylene is, for example, ethylene and about 4 to 17% by weight, preferably about 5 to 15% by weight, of other α-olefins such as butene, hexene, octene, decene, and 4-methylpentene-1. Is produced by copolymerizing with a Ziegler-type catalyst or Phillips-type catalyst used in the production of medium- and high-pressure method high-density polyethylene. This product has a conventional high density polyethylene with a short branched structure by a copolymerization component, and the density is appropriately reduced by utilizing this short chain branching to 0.91 to 0.95 g.
/ Cm ^3, which is a polyethylene having a structure that is more linear than conventional branched low-density polyethylene and has more branches than high-density polyethylene.

In addition to the above-mentioned linear low-density polyethylene, linear high-density polyethylene having a density of 0.965 g / cm ³ or less can be used as the linear polyethylene of (a) in the present invention. Examples of the polybutene resin that is the resin component (b) include butene-1, butene-2, isobutene,
The thing which polymerized butane etc. using the Ziegler-Natta catalyst etc., Preferably, the homopolymer of 1-butene and the copolymer of butene and ethylene whose ethylene content is 10 weight% or less are mentioned. Preferably, the weight average molecular weight is 2
50,000 to 3 million, particularly preferably 1 million to 300
10,000, the density is 0.93 g / cm ³ or less, preferably 0.1.
87-0.92 g / cm ³ , melt index 10
Resins having a high stereoregularity having a helical structure in the range of g / 10 minutes or less, preferably 0.1 to 5 g / 10 minutes are mentioned.

The melt index in the present invention is JIS K which is a reference standard of JIS K 6760.
It is a value measured in accordance with the condition 4 of Table 1 of 7210. The density is a value measured according to JIS K6760. In the present invention, the ratio of (a) polyethylene resin and (b) polybutene resin used is (a) 9
9 to 20 parts by weight, preferably 95 to 50 parts by weight,
(B) is selected from the range of 1 to 80 parts by weight, preferably 5 to 50 parts by weight.

As the filler contained in the resin composition of the present invention, known inorganic or organic fillers can be used. As the inorganic filler, for example, calcium carbonate, talc, clay, kaolin, silica, diatomaceous earth, magnesium carbonate, barium carbonate, magnesium sulfate, barium sulfate, calcium sulfate, aluminum hydroxide, zinc oxide, magnesium hydroxide, calcium oxide, Examples thereof include magnesium oxide, titanium oxide, alumina, mica, asbestos powder, glass powder, shirasu balloon, zeolite, and silicate clay. Of these, calcium carbonate, talc, clay, silica, diatomaceous earth, and barium sulfate are particularly preferable.

Examples of the organic filler include cellulosic powders such as wood powder and pulp powder. The fillers may be used alone or as a mixture.
The filler having an average particle size of 30 μm or less, preferably 10 μm or less, and particularly preferably 0.8 to 5 μm is used.

In the present invention, the filler is used after being surface-treated with a fatty acid such as stearic acid or a metal salt thereof according to a conventional method in view of dispersibility in the polyolefin resin and stretchability of the polyolefin resin. Is preferred. The amount of the filler added is 100 to 400 parts by weight, preferably 120 to 300 parts by weight, based on 100 parts by weight of the total of the resins (a) and (b).

The plasticizer is not particularly limited, and various known ones can be used. Examples thereof include phthalate ester plasticizers, phosphoric acid ester plasticizers, trimellitic acid ester plasticizers, dipentaerythritol ester plasticizers, and the like. A particularly preferable compound as a plasticizer has an ester bond or an amide bond in the molecule and has a molecular weight of 100 or more, preferably 35.
0 or more, particularly preferably 350 to 1500, the boiling point at atmospheric pressure is 200 ° C or more, preferably 250 ° C or more, particularly preferably 250 to 500 ° C, and the melting point is 100 ° C.
Or less, preferably 50 ° C. or less, particularly preferably 30 to −
It is a compound which is 60 ° C.

Specific examples of the compound having an ester or amide bond in the molecule include dioctyl phthalate, trioctyl trimellitate, triisodecyl trimellitate, diisodecyl phthalate, oleic acid amide, stearic acid amide and dipentaerythritol-. 2-ethylhexanoic acid ester and the like can be mentioned. Among these, trioctyl trimellitate, diisodecyl phthalate and dipentaerythritol-2-ethylhexanoic acid ester are particularly preferable.

The proportion of the plasticizer used is 1 to 100 parts by weight, based on 100 parts by weight of the resins (a) and (b).
It is preferably 5 to 40 parts by weight. Further, in the present invention, the resin composition may further contain a radical generator. As the radical generator, for example, the decomposition temperature at which the half-life is 1 minute is 130 to 300 ° C., preferably 160 to 300 ° C.
Those having a temperature in the range of 240 ° C. are preferable, and specific examples of such a radical generator include dicumyl peroxide,
2,5-Dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-bis (t-
Examples include peroxides such as butylperoxy) -3-hexyne, α, α′-bis (t-butylperoxyisopropyl) benzene, dibenzoyl peroxide, and di-t-butyl peroxide.

The proportion of the radical generator used is 0.000 relative to 100 parts by weight of the total of the resins (a) and (b).
1 to 0.1 parts by weight, preferably 0.001 to 0.07
Parts by weight. Furthermore, in the present invention, a heat stabilizer, an ultraviolet stabilizer, a pigment, an antistatic agent, a polyolefin resin,
Known additives such as a fluorescent agent may be added within a range that does not impair the effects of the present invention.

Next, the method for producing the porous film of the present invention will be described. The porous film of the present invention is particularly preferably formed into an unstretched film or sheet by a T-die molding method, an air-cooled or water-cooled inflation molding method. Next, the film is made porous by uniaxially stretching the unstretched film in the film take-up direction (longitudinal direction) or biaxially stretching in the longitudinal direction and the transverse direction.

In the air-cooled inflation molding method, the respective components are kneaded by a kneader such as an extruder or a Banbury mixer, then pelletized, and then extruded into a tube shape with a cylindrical die, air is enclosed and expanded. This is a method of cooling. In inflation molding, the blow-up ratio (BUR) is usually 1.5 to 8, preferably 2 to 6.
The height of the frost line should be adjusted to 2 to 50 times, preferably 5 to 20 times the diameter of the annular slit of the die.

The unstretched laminated film is at least uniaxially stretched, but from the viewpoint of manufacturing cost, it is preferable to stretch it uniaxially in the machine direction. A roll stretching method is usually used for the uniaxial stretching, but a tubular stretching method can also be used. The stretching treatment may be performed in one stage or in multiple stages of two or more stages. The stretching temperature is about 100 ° C lower than the melting point of the resin to 20 ° C lower than the melting point, preferably 90 ° C lower than the melting point of the resin temperature to 50 ° C lower than the melting point.
It is a low temperature. The stretching ratio is usually 1.
It is 2 to 8 times, preferably 1.5 to 4.5 times.

The thickness of the porous film or sheet of the present invention is 50 μm or less, preferably 15 to 40 μm,
Moisture permeability 1000~6000g / m ² · 24hr, and preferably 1500~4800g / m ² · 24hr.
The porous film or sheet of the present invention has improved lateral strength, improved strength balance with the longitudinal direction, and tear strength as compared with conventional porous films or sheets. Usually, longitudinal strength transverse strength at 55kg / cm ² ~90kg / cm ² is 160kg / cm ² ~220kg / cm ² and the balance is good, moreover, tear strength 6.5kg / cm~16k
g / cm is obtained.

The porous film or sheet of the present invention is suitable for use as an exterior film or sheet for sanitary articles such as diapers. In the case of a sanitary article, the porous film or sheet of the present invention, a water-absorbent material layer made of a water-absorbent polymer or the like, and a water-permeable material layer made of a nonwoven fabric or the like may be stacked. Examples of the water-absorbent material layer of the present invention include a laminate of a plurality of water-absorbent papers, a linear kraft pulp wrapped with a water-absorbent paper, or a superabsorbent polymer such as "Product Name: Diamond". Wet ”
(Made by Mitsubishi Yuka Co., Ltd.), “Product name: Aqua Reserve” (made by Nippon Synthetic Chemical Co., Ltd.), and the like used in conventional sanitary products.

Further, as the water-permeable material layer of the present invention,
Any material may be used as long as it is water permeable, but it is formed from hydrophobic fibers mainly composed of polyester fibers and polyolefin fibers, which are devised so as to prevent the absorbent liquid from returning from the water absorbent material layer. Preferred are non-woven fabrics and woven fabrics. For sanitary goods, an appropriate number of water-absorbent materials, paper for preventing scattering, and the like are placed on a porous film. At that time, the thickness of the water-absorbent material layer is usually about 5 to 20 mm. Further, a non-woven fabric or a woven fabric may be appropriately laminated thereon with a paper or the like interposed therebetween, and they may be integrally formed with an adhesive tape or the like and molded.

[0024]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. The physical properties shown in the examples of the present invention were measured according to the following methods. (1) Tensile strength 25 mm (width) according to JIS L1085-1977
Using a test piece of × 100 mm (length), pulling speed 300
It was measured at mm / min. (2) Water vapor transmission rate (g / m ² · 24 hr) According to JIS Z0208-1976, it was measured at a temperature of 30 ° C and a relative humidity of 90%. (3) Air permeability (sec / 100 cc) Measured according to JIS P8117-1963.

Example 1 Linear low density polyethylene resin (melt index:
1.0 g / 10 minutes, density: 0.921 g / cm ³ , copolymerization component: butene-1, copolymerization amount: 10% by weight, melting point: 1
20 ° C.) 80 parts by weight, polybutene-1 (melt index: 1.0 g / 10 minutes, density: 0.910 g / c
m ³ , weight average molecular weight: 1.3 million) 20 parts by weight, dipentaerythritol ester plasticizer {Asahi Denka Kogyo Co., Ltd.
Product name "Adeka Sizer UL-6"} 7 parts by weight and 180 parts by weight of calcium carbonate surface-treated with stearic acid and having an average particle size of 0.9 µm are mixed with a Henschel mixer, and then mixed with a biaxial kneader at 180 ° C. Kneaded and granulated. After that, a film was formed under the following conditions, and then the film was made porous under the following conditions to obtain a 37 μm porous film having a beautiful surface and no stretching unevenness.

[0026]

[Table 1] Film formed into a film having a thickness of 65 µm by inflation molding Cylinder temperature: 170-190-210-230
℃ head, die temperature: 200 ℃ Die diameter (D): 100 mm Pulling speed: 8 m / min Blow ratio: 3.0 Frost line height (FLH): 700 mm Folding diameter: 471 mm Uniaxial stretching with a roll stretching machine Stretching temperature: 50 ° C Stretching ratio: 2.5 times Stretching speed: 11.0 m / min The performance of this film is shown in Table-1.

On the above film, a paper having a thickness of about 200μ,
About 15m thick made of linear pulp containing super absorbent polymer
m liquid absorber, thickness of about 200μ paper and basis weight of about 15g
/ M ²Nonwoven fabric of polyester fiber
By embodying and then fixing them with tape
Therefore, the disposable diaper could be manufactured well.

Example 2 Linear high density polyethylene resin (melt index:
0.03 g / 10 minutes, density: 0.942 g / cm ³ ) 7
A porous film was obtained in the same manner as in Example 1 except that 0 parts by weight and 30 parts by weight of polybutene-1 of Example 1 were used. The performance of the obtained film is shown in Table 1. Using this film, a disposable diaper could be manufactured as well as in Example 1.

Example 3 The porosity was the same as in Example 1 except that 50 parts by weight of the linear low density polyethylene of Example 1, 30 parts by weight of polybutene-1 and 20 parts by weight of the linear high density polyethylene of Example 2 were used. I got a film. The performance of the obtained film is shown in Table 1. Using this film, a disposable diaper could be manufactured as well as in Example 1.

Example 4 Radical generator 2,5-dimethyl-2,5-bis (t-
A porous film was obtained in the same manner as in Example 1 except that 0.02 parts by weight of butylperoxy) -3-hexyne was added and mixed. The performance of the obtained film is shown in Table 1. Using this film, a disposable diaper could be manufactured as well as in Example 1.

Example 5 Polybutene-1 was melt indexed 0.2 g / 10
Min, density 0.890 g / cm ³ , weight average molecular weight: 30
A porous film was obtained in the same manner as in Example 1 except that the physical properties were changed to 100,000. The performance of the obtained film is shown in Table 1. Using this film, a disposable diaper could be manufactured as well as in Example 1.

Comparative Example 1 Linear low density polyethylene resin (melt index:
1.0 g / 10 minutes, density: 0.920 g / cm ³ ) 90
A porous film was obtained in the same manner as in Example 1 except that the weight part and the branched low-density polyethylene resin were changed to 10 parts by weight. The performance of the obtained film is shown in Table 1. A disposable diaper was manufactured in the same manner as in Example 1, but the strength was weak, and when the fixing tape was peeled off, a tear was generated in the exterior film (porous film).

[0033]

[Table 2]

[0034]

According to the present invention, when a porous film made of a combination of a polyethylene resin and a specific amount of polybutene resin is used, strength, breathability and moisture permeability are good, and disposable hygiene products such as diapers and sanitary products can be obtained. It can be manufactured advantageously.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Akagi 3-10, Shiodotsu, Kurashiki-shi, Okayama Mitsubishi Kasei Co., Ltd. Mizushima Plant

Claims (5)

[Claims] 1. A filler 99 to 20 parts by weight, (b) a polybutene resin 1 to 80 parts by weight, and a filler 100 to 40 per 100 parts by weight of the total amount of (a) and (b).
A porous film or sheet formed from a resin composition containing 0 parts by weight and 1 to 100 parts by weight of a plasticizer. 2. The density of polyethylene resin is 0.910.
0.965 g / cm ³And melt index is 20g /
The porous film according to claim 1, which is 10 minutes or less, or
Sheet. 3. The density of polybutene resin is 0.93 g / c.
The porous film or sheet according to claim 1, which has a m ³ or less. 4. The porous composition according to claim 1, wherein the resin composition according to claim 1 contains 0.0001 to 0.1 part by weight of a radical generator with respect to 100 parts by weight of the total amount of the polyethylene resin and the polybutene resin. Film or sheet. 5. A hygiene article comprising at least a porous film, a water-absorbent material layer and a water-permeable material layer, wherein the porous film is (a) polyethylene resin 9
9 to 20 parts by weight, (b) 1 to 80 parts by weight of polybutene resin, and 100 to 400 parts by weight of a filler and 1 to 100 parts by weight of a plasticizer per 100 parts by weight of the total amount of (a) and (b). A hygiene article characterized by being formed from a resin composition.