KR100358711B1 - Composition for air permeable film of high processability and production of air permeable film - Google Patents

Abstract

The present invention relates to a compound composition for a breathable film excellent in processability and a method for producing a breathable film using the same, and more specifically, in a compound composition for breathable film, a linear low density having a melt index of 0.5 to 5 as the first component Polyethylene, one or two or more ethylene-based low crystalline polymers as a second component, 50 to 200 parts by weight of an inorganic filler with respect to 100 parts by weight of the total of the first and second components as a third component, and the whole polyethylene Of the amorphous region has a range of 3.0 ≦ Σω (1-Ｘ _C ) ≦ 30, where ω is the weight ratio of the second component to the sum of the first component and the second component, and Ｘ _C is the second It is characterized by the crystallinity degree of a component. The breathable film composition according to the present invention was able to improve the melt rate of the pellets in the extruder, thereby removing the surging phenomenon during high-speed production, it was possible to have a soft texture such as pure cotton without causing a decrease in physical properties of the breathable film.

Description

Compound composition for breathable film having excellent processability and manufacturing method of breathable film using the same {Composition for air permeable film of high processability and production of air permeable film}

The present invention relates to a compound composition for a breathable film excellent in processability and a method for manufacturing a breathable film using the same, and more particularly, to a compound composition for a breathable film to have a high processability when forming a film to enable high-speed production A method for producing a breathable film.

There are many methods for producing a breathable or porous film, but among them, the most economical and commercially available method is to mix the inorganic filler with the polyolefin resin and to separate the interface between the resin and the filler by uniaxial or biaxial stretching after film molding. To form fine holes.

On the other hand, looking at the prior art of manufacturing a breathable film by adding an inorganic filler, first, the first category, European Patent No. 66,672 (1982) or European Patent No. 307,116 (1988), European Patent No. 459,142 ( 1991), European Patent Publication No. 779,325 (1997 application), such as adding a third material of fatty acids to polyolefins and inorganic fillers to increase the softness of the film, or to improve the imbalance of physical properties in the longitudinal and transverse direction of the film The solution is to solve the problem. Such a third additive is capable of mixing and dispersing a high content of inorganic filler in the extrusion process, and plays an important role such as to produce a uniform stretch during film processing, thereby achieving the core contents of the present inventions.

In addition, the second category uses techniques such as embossing on the post-processing of the film to control the mechanical strength of the breathable film (Ep. 232,060 (1987)), or to increase the moisture permeability and improve the tear strength ( US Patent No. 4,777,073 (1988)).

However, the first category of technology is disadvantageous in terms of economical efficiency because it requires the use of an expensive third material, the compatibility with polyolefins decreases, the tensile strength of the film decreases, and the additives leak out to the film surface during storage after film molding. Have The second category of techniques is the control of film properties on post-processing, which has a disadvantage compared to the range of change in film properties that can be given in polyolefin resin compositions. Recent trends have emphasized the high-speed production of breathable films to reduce the manufacturing cost of breathable films, but currently commercialized compositions contain more than 50% of calcium carbonate in polyolefins, resulting in surging or film thickness irregularities, There is a limit to increase the production speed due to poor workability such as occurrence. In particular, surging is a phenomenon that thickness variation occurs due to uneven extrusion amount, which is pointed out as the biggest problem in high speed film production. This surging phenomenon is closely related to the melting characteristics of the resin, and it is known that the pumping rate of the resin melt and the melting rate of the solid resin pellet in the extruder are imbalanced (MJ Stevens and JACovas, 'Extruder Principles And Operation ', p 359, Chapman & Hall, London, 1995). In addition, the skin texture such as the cotton of the breathable film preferred by the end consumer is also a demanding property.

Accordingly, in the present invention, the ethylene-based low crystalline polymer was blended with the linear low density polyethylene resin to improve the melt rate of the pellets in the extruder. Accordingly, the surging phenomenon was eliminated during high-speed production, and the physical properties of the breathable film were not caused. It was possible to have a soft texture such as cotton, and the present invention was completed based on this.

Accordingly, an object of the present invention is to provide a compound composition for breathable film to have a high processability when forming a film to enable high-speed production.

Another object of the present invention to provide a method for producing a breathable film using the composition.

Compound composition for breathable film of the present invention for achieving the above object is a compound composition for breathable film, linear low density polyethylene having a melt index of 0.5 to 5 as a first component, one or two or more ethylene-based low as a second component Crystalline polymer, consisting essentially of 50 to 200 parts by weight of an inorganic filler with respect to 100 parts by weight of the sum of the first and second components as a third component, the amount of the amorphous region in the total polyethylene is 3.0≤Σω (1-Ｘ _C ) ≦ 30, wherein ω is a weight ratio of the second component to the sum of the first component and the second component, and Ｘ _C is a crystallinity of the second component.

The production method of the present invention for achieving the above another object is to produce at 1.5 to 2.5 times the production rate by uniaxially or biaxially stretching the composition while extruding the composition into a film with a T-die extruder.

Looking at the present invention in more detail as follows.

As described above, according to the present invention, the amount of amorphous region of the ethylene-based low crystalline polymer is appropriately adjusted so that various problems such as surging during high-speed production, non-uniform film thickness, and hole generation during film forming are possible. The present invention relates to a breathable compound resin composition and a method for manufacturing a breathable film using the same to solve the problems and to significantly increase the production speed, and to have the same texture as the cotton of the breathable film.

The composition according to the present invention consists essentially of a linear low density polyethylene resin, an ethylene-based low crystalline polymer and an inorganic filler, and may optionally further comprise a lubricant, an antioxidant and / or titanium dioxide.

The first component of the composition according to the present invention is a linear low density polyethylene resin (LLDPE) having a melt index (Melt Index) of 0.5 to 5 range. In particular, the copolymerizable monomers usable in the preparation of the resin are selected from the group consisting of butene (1-Butene), hexene (1-Hexene) and octene (1-Octene), in the present invention, a linear low density selected from at least 1 or 2 Polyethylene resin is used. At this time, when the melt index is less than 0.5, the processing load during the production of the film increases, and when it exceeds 5, the physical properties of the manufactured breathable film tend to decrease.

In addition, the second component is one or two or more ethylene-based low crystalline polymers, wherein the amount of the amorphous region of the entire polyethylene resin (the first component and the second component) is 3.0 ≦ Σω (1-Ｘ _C ) ≦ 30 The content is adjusted to have a range. Is the weight ratio of the second component to the sum of the first component and the second component, and _C is the crystallinity of the second component. In general, the density (ρ _C ) of the crystal region of the polyethylene is 1.0 g / ml, and the density (ρ _A ) of the amorphous region is 0.85 g / ml (DWVan Krevelen, "Properties of Polymers", p574, Elsevier Scientific Publishing Co.) , Amsterdam, 1976). When the degree of crystallinity of the ethylene-based low crystalline polymer is expressed as Ｘ _C (weight ratio of the crystalline region) and the weight ratio of the ethylene-based low crystalline polymer in the total polyethylene is expressed as ω, Σω (1-Ｘ _C ) is the amount of amorphous region in the entire polyethylene. do. On the other hand, since ρ _C = 1.0 g / ml and ρ _A = 0.85 g / ml, when the density of the ethylene-based low crystalline polymer is represented by ρ, the relationship between _C and ρ is represented by the following formula (1).

1-Ｘ _C = 5.667 (1 / ρ-1)

Therefore, Σω (1-Ｘ _C ) can be calculated by the following equation.

Σω (1-Ｘ _C ) = Σω {5.667 (1 / ρ-1)}

The degree of crystallinity (Ｘ _C ) of the ethylene-based low crystalline polymer used in the present invention is 0.5 or less, using low density polyethylene that is gas phase polymerized, or butene, propylene, hexene, octene, vinyl acetate, It is manufactured by copolymerizing 1 or 2 or more of acrylic acid. Representative examples of commercial production include Mitsui Sekka trade name "Tafmer", DuPont Dow Elastomers trade name "Affinity" or "Engage", DuPont Mitsui Polychemicals trade name " Evaflex ", the trade name" Primacor "from Dow Chemicals, and the like. As described above, the ethylene-based low-crystalline polymer is in amounts such that the range of the total amount of the amorphous polyethylene regions 3.0≤Σω (1-X _C) ≤30 is appointed. If the amount of amorphous region is less than 3.0, the melt non-uniformity in the extruder during high-speed production is not sufficiently improved as desired, there is a limit to increase the production rate, and the manufactured breathable film also feels less like cotton. In addition, if the amount of the amorphous region is greater than 30, the overall physical properties of the breathable film occurs to lose the commercial value.

As the third component, an inorganic filler is used in an amount of 50 to 200 parts by weight based on 100 parts by weight, which is the sum of the polyolefin resins from the first component to the second component. At this time, if the use amount is out of the range, the air permeability effect is lowered or the physical properties tend to be lowered. Calcium carbonate and barium sulfate are preferable, and the said inorganic filler is preferable in the range whose average particle size is 0.7-5 micrometers. If the average particle size is less than 0.7㎛, there is a problem in that the kneading property is not good to exhibit the desired physical properties when manufacturing the breathable compound, if the average particle size exceeds 5㎛, the occurrence frequency of pores during the manufacture of the breathable film increases the number of defects. In addition, the inorganic filler may be used without coating, or may be used coated with stearic acid fatty acid.

The fourth component is added in an amount of 0.05 to 3 parts by weight based on 100 parts by weight which is the sum of the polyolefin resins from the first component to the second component as a processing lubricant. If the amount of the lubricant is less than 0.05 parts by weight can not play a role of the lubricant during processing, if more than 3 parts by weight die build-up (Die Build-up) phenomenon occurs when forming the breathable film to reduce the production efficiency. The lubricant may be used in the form of calcium stearate, zinc stearate or a mixture thereof.

The fifth component is used as an antioxidant at 0.05 to 3 parts by weight based on 100 parts by weight of the sum of the polyolefin resins from the first component to the second component. If the amount of the antioxidant is less than 0.05 parts by weight, the antioxidant effect can not be expressed as much as desired, and if it exceeds 3 parts by weight, an increase in the antioxidant effect can no longer be expected. As the antioxidant, a phenolic antioxidant, a phosphoric acid antioxidant or a mixture thereof may be used.

In addition, as a sixth component added to increase the whiteness or hiding power of the film, titanium dioxide may be used in an amount of 0.1 to 3 parts by weight based on 100 parts by weight of the total of the first component and the second component.

The composition thus formed may be uniaxially or biaxially stretched while extruding the film into a T-die extruder to produce a breathable film at a production rate of 1.5 to 2.5 times the normal production rate. In general, the production rate can be adjusted according to the characteristics of the machine and the use of the film, in the present invention can exhibit a production rate of 1.5 to 2.5 times in the same machine.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to the following examples.

Comparative Example 1

In this Comparative Example, a breathable compound was prepared by mixing only calcium carbonate as an inorganic filler in a linear low density polyethylene (M.I. = 2.0, density = 0.919, copolymerized monomer = octene) for general casting.

100 parts by weight of the linear low-density polyethylene, 0.3 parts by weight of antioxidant (Kolong Emulsification, KB9112C), and 0.3 parts by weight of zinc stearate (Dubon Chemical) were mixed with a super mixer using a twin screw extruder maintained at an average extrusion temperature of 190 ° C. Injected into the main inlet and the average particle size is 1.5㎛, 100 parts by weight of calcium carbonate coated with stearic acid was injected into the side inlet by melt mixing and extrusion to prepare a pellet. The compound was uniaxially stretched twice in the machine direction using a T-die film forming machine having an extruder screw diameter of 130 mm to prepare a breathable film having a basis weight of 35 g / m ² at a production speed of 40 m / min. 1 is shown.

Example 1

In this embodiment, low-density polyethylene (hereinafter referred to as 'LDPE') and ethylene vinyl acetate (hereinafter referred to as 'EVA') which are gas phase polymerized with an ethylene-based low crystalline polymer are used to increase the amount of amorphous region of polyethylene at high speed. Film production was possible to produce breathable compounds.

60 parts by weight of linear low density polyethylene (SK Co., Ltd., MI = 2.0, density = 0.99, copolymerization monomer = octene) and LDPE (Hanhwa, MI = 5.3, crystallinity = 0.5) using a twin screw extruder whose extrusion temperature is maintained at an average temperature of 190 ° C. 20 parts by weight, EVA (Dupont-Mitsui Petrochemical, VA content = 25%, MI = 2, Crystallinity = 0.26) 20 parts by weight, 0.3 parts by weight of antioxidant (Kolon Oil, KB9112C), 0.3 parts by weight of zinc stearate (Dubon Chemical) 3 parts by weight of titanium oxide masterbatch (TiO ₂ content = 60%) were mixed with a super mixer, and then introduced into the main inlet, and 100 parts by weight of calcium carbonate coated with stearic acid was added to the side inlet with an average particle size of 1.5 μm. While melt mixing and extrusion was prepared in the form of pellets. The prepared compound was uniaxially stretched twice in the machine direction using a T-die film forming machine having an extruder screw diameter of 130 mm to prepare a breathable film having a basis weight of 35 g / m ² at a production speed of 85 m / min. 1 is shown.

Example 2

In this embodiment, using an ethylene-based low crystalline polymer LDPE and DuPont Dow Elastomer brand name 'Engage' to increase the amount of the amorphous region of the polyethylene to produce a high-speed breathable compound.

35 parts by weight of linear low density polyethylene (SK Co., MI = 2.0, density = 0.99, copolymerization monomer = octene) and linear low density polyethylene (Hanhwa, MI = 2.0, density =) 0.919, copolymerized monomer = hexene) 35 parts by weight, LDPE (Hanhwa, MI = 5.3, crystallinity = 0.5) 20 parts by weight, 10 parts by weight of DuPont Dow Elastomer's 'Engage' 8100 (MI = 1.0, crystallinity = 0.15), 0.3 parts by weight of an antioxidant (Kolon Emulsification, KB9112C), 0.15 parts by weight of zinc stearate and calcium stearate (Dubon Chemical), respectively, were mixed with a super mixer, and injected into the main inlet, and the average particle size was 1.5 µm and coated with calcium stearate. 100 parts by weight were injected into a side inlet, melt mixed and extruded to prepare pellets. The prepared compound was uniaxially stretched twice in the machine direction using a T-die film forming machine having an extruder screw diameter of 130 mm to prepare a breathable film having a basis weight of 35 g / m ² at a production speed of 80 m / min. 1 is shown.

Example 3

In the present embodiment, using an LDPE and Mitsui Seka brand name 'Tafmer' as an ethylene-based low crystalline polymer, a breathable compound was prepared to increase the amount of amorphous region of polyethylene to enable film production at high speed.

50 parts by weight of linear low density polyethylene (SK Co., Ltd., MI = 2.0, density = 0.99, copolymerized monomer = octene) and linear low density polyethylene (Hanhwa, MI = 2.0, density =) using a twin screw extruder whose extrusion temperature is maintained at an average temperature of 190 ° C. 0.919, copolymerized monomer = butene) 20 parts by weight, LDPE (Hanhwa, MI = 5.3, crystallinity = 0.5) 20 parts by weight, 10 parts by weight of 'Tafmer' A-4085 (MI = 3.6, crystallization degree = 0.23) from Mitsui Seka 0.3 parts by weight of antioxidant (Kolong Emulsification, KB9112C), 0.15 parts by weight of zinc stearate and calcium stearate (Dubon Chemical), respectively, were mixed with a super mixer, and introduced into the main inlet. The average particle size was 1.0 µm and 100 parts of untreated barium sulfate. The part was injected into the side inlet, melt mixed, and extruded to prepare pellets. The prepared compound was uniaxially stretched twice in the machine direction using a T-die film forming machine having an extruder screw diameter of 130 mm to prepare a breathable film having a basis weight of 35 g / m ² at a production speed of 75 m / min. 1 is shown.

Evaluation of Breathable Film Properties According to the Composition of Compounds Item Comparative Example 1 Example One 2 3 Linear low density polyethylene (M.I. = 2.0, density = 0.919, octene) 100 60 35 50 Linear low density polyethylene (M.I. = 2.0, density = 0.919, hexene) 35 Linear low density polyethylene (M.I. = 2.0, density = 0.919, butene) 20 Low Density Polyethylene (LDPE) (M.I. = 5.0, Crystallinity = 0.5) 20 20 20 'Engage' 8100 (M.I. = 1.0, Crystallinity = 0.15) 10 'Evaflex' EV360 (M.I. = 2.0, VA content = 25%, crystallinity = 0.26) 20 'Tafmer' A-4085 (M.I. = 3.6, Crystallinity = 0.23) 10 Antioxidant (KB9112C) 0.3 0.3 0.3 0.3 Bow Calcium Stearate Zinc Stearate 0.3 0.3 0.150.15 0.150.15 Calcium carbonate 100 100 100 Barium sulfate 100 TiO ₂ M / B 3 Elongation ratio 2 2 2 2 Film properties Max film production speed (m / min) 40 85 80 75 Water vapor permeability (WVTR g / ㎡24hrs) 5300 5100 5500 4300 Softness (g), MD 300 220 230 230 Tensile strength (g) MD (longitudinal direction) TD (lateral direction) 1700600 1550550 1600580 1600580 Tensile Elongation (%) MD (longitudinal direction) TD (lateral direction) 170490 160470 170500 160480

Physical properties shown in Table 1 were measured by the following method.

Softness: The longitudinal tensile (mechanical) tensile strength at 3% elongation was measured according to KS M3016.

* Maximum film production rate: Using the film equipment used in the actual production, the maximum production linear velocity before the occurrence of the thickness deviation due to the extrusion unevenness observed with the naked eye was observed in 5 m / min unit.

* Water vapor permeability: According to ASTM E96-92, the moisture permeability according to the increase in weight after storage for a certain period of time under constant temperature and humidity conditions was measured.

* Tensile Strength and Tensile Elongation: Tensile strength and elongation at break in the longitudinal (machine direction) and transverse (machine vertical) directions were measured according to KS M3016.

As can be seen in Table 1, the breathable film composition according to the present invention was able to improve the melt rate of the pellets in the extruder, thereby eliminating the surging phenomenon during high-speed production, and does not cause the physical properties of the breathable film It could have a soft texture like cotton.

Claims (8)

Compound composition for breathable film, comprising: linear low density polyethylene having a melt index of 0.5 to 5 as a first component, one or two or more ethylene-based low crystalline polymers as a second component, and the first and second components as a third component 50 to 200 parts by weight of an inorganic filler based on 100 parts by weight of the sum, and the amount of the amorphous region in the total polyethylene has a range of 3.0≤Σω (1-Ｘ _C ) ≤30, where ω is It is a weight ratio of the 2nd component with respect to the sum of 1 component and a 2nd component, and _C is a compound composition for breathable films, characterized by the crystallinity degree of a 2nd component. The compound according to claim 1, wherein the linear low density polyethylene resin is a linear low density polyethylene resin selected from one or two or more of the linear low density polyethylene resins selected from the group consisting of butene, hexene, and octene. . The method of claim 1, wherein the ethylene-based low crystalline polymer is an ethylene-based polymer having a crystallinity of 0.5 or less, 1 from the group consisting of butene, propylene, hexene, octene, vinyl acetate and acrylic acid in the gas phase polymerization of low density polyethylene, or polyethylene polymerization Or a polyethylene prepared by copolymerization with two or more selected copolymerization monomers. The compound composition for breathable film according to claim 1, wherein the inorganic filler is calcium carbonate, barium sulfate, or a mixture thereof, and has an average particle size of 0.7 to 5 µm untreated or coated with fatty acid. The composition of claim 1, further comprising 0.05 to 3 parts by weight of a lubricant comprising calcium stearate, zinc stearate, or a mixture thereof as a fourth component based on 100 parts by weight of the sum of the first and second components. Compound composition for air permeable films. 2. The composition of claim 1, wherein the composition further comprises 0.05 to 3 parts by weight of a phenolic antioxidant, a phosphoric acid antioxidant, or a mixture thereof, based on 100 parts by weight of the total of the first and second components. Compound composition for breathable film. The compound composition for breathable film according to claim 1, wherein the composition further comprises titanium dioxide at 0.1 to 3 parts by weight based on 100 parts by weight of the total of the first and second components. A breathable film, characterized in that the composition according to any one of claims 1 to 7, uniaxially or biaxially stretched by extrusion into a film with a T-die extruder to produce at a production rate of 1.5 to 2.5 times the normal production rate. Manufacturing method.