KR980009363A - RESIN COMPOSITION OF POROUS FILM AND PROCESS FOR PRODUCING POROUS FILM USING THE SAME - Google Patents

Abstract

The present invention relates to a resin composition for a porous film comprising 100 parts by weight of a polyolefin resin, 0.5 to 40 parts by weight of a cyclopentadiene petroleum resin or hydrogenated cyclopentadiene petroleum resin, and 20 to 100 parts by weight of an inorganic filler, And then stretching the film to at least one or more axes. The porous film produced by the resin composition and the manufacturing method of the present invention is excellent in mechanical properties such as tensile strength, elongation and tearing strength, and is also excellent in the moisture permeability, so that the waterproof cover of the paper diaper passes through air and moisture, It can be used in various industrial applications such as clothing materials having characteristics that do not pass through, and building materials that prevent condensation of buildings.

Description

RESIN COMPOSITION OF POROUS FILM AND PROCESS FOR PRODUCING POROUS FILM USING THE SAME

The present invention relates to a resin composition for a porous film and a method for producing the porous film using the same. More specifically, the present invention relates to a resin composition for a porous film comprising 100 parts by weight of a polyolefin resin, 0.5 to 40 parts by weight of a cyclopentadiene petroleum resin or hydrogenated cyclopentadiene petroleum resin, and 20 to 100 parts by weight of an inorganic filler And a method for producing a porous film which is excellent in tensile strength, elongation, tear strength and moisture permeability in the longitudinal and transverse directions of the film by melting the electric resin composition and forming the film into a film and drawing the film in at least one axial direction.

Porous films are used in various industrial applications such as sanitary materials used as waterproof covers of paper diapers, clothing materials having the characteristics of passing air and moisture but not allowing water to pass through, and construction materials for preventing condensation of buildings . This is because the size of the pores formed in the porous film is so small that water can not pass through it, so that water can not pass through it and can be used for the above purposes as air and moisture pass through.

In this connection, a number of methods are known for forming a resin composition containing a polyolefin resin and various incompatible inorganic fillers into a film, followed by stretching the film to produce a porous film. For example, Japanese Patent Laid-Open No. 58-149303 discloses a porous film produced by molding a resin composition obtained by mixing a polyolefin resin, a filler, and a liquid or wax-like hydrocarbon polymer, into a film, and stretching the resin composition. However, in such a porous film, when the film is stretched in the uniaxial direction, the balance between the tensile strength and the tear strength, which are the mechanical properties in the longitudinal direction and the transverse direction, which are the stretching direction of the film, is remarkably reduced. That is, the tensile strength in the longitudinal direction in the stretching direction of the film is extremely excellent, but the tensile strength in the transverse direction is significantly lowered and the tear strength in the stretching direction is also significantly reduced. Accordingly, when such a film is applied to a diaper, wrinkles are easily generated as tension is applied to the film in the diaper production process, and in some cases, rubber is applied to the diaper wing portion in order to impart panty- If a film having a tensile strength and elongation at break is used at this time, breakage may occur and the productivity of the diaper may deteriorate significantly.

As a method for solving the problem that the tear strength in the stretching direction and the tensile strength in the transverse direction are extremely weak in such a porous film, there is a method of reducing the stretching ratio as far as possible. However, in the case of low stretching, It is impossible to provide a porous film suitable for use because of insufficient moisture permeability. In order to solve the above problems, Japanese Patent Laid-Open No. 62-280233 discloses a polyolefin mixed with a polyolefin produced by the reaction of a polybasic acid and a polyhydric alcohol. However, in this method, since the polyester is not compatible with polyolefin, It raises concern for. Further, in JP-A-58-15538, liquid polybutadiene, liquid polybutene, and terminal hydroxy liquid polybutadiene are mixed as a third component in addition to polyolefin and an inorganic filler. However, when the liquid material is mixed, There is often a problem that the liquid material moves to the surface.

In addition, when a large amount of an inorganic filler is added to a polyolefin resin to form a film and then the porous film is stretched, the moisture permeability of the porous film is increased as the content of the inorganic filler is increased. However, mechanical properties such as tensile strength, elongation, Thereby exposing the problem of deteriorating physical properties.

Under these circumstances, the inventor of the present invention has conducted intensive studies to solve the above-described conventional problems. As a result, the present inventors have found that even when the amount of the inorganic filler used is less than that of the conventional method and the stretching ratio is reduced, the moisture permeability is excellent, The present inventors have found a resin composition capable of producing a porous film having excellent mechanical properties such as mechanical strength and ductility and excellent workability.

As a result, a main object of the present invention is to provide a resin composition for a porous film comprising 100 parts by weight of a polyolefin resin, 0.5 to 40 parts by weight of a cyclopentadiene petroleum resin or hydrogenated cyclopentadiene petroleum resin and 20 to 100 parts by weight of an inorganic filler .

Another object of the present invention is to provide a method for producing a porous film in which an electrical resin composition is melted, molded into a film, and at least uniaxially stretched.

Hereinafter, the present invention will be described more specifically.

The present invention provides a resin composition of a porous film comprising a polyolefin resin, a cyclopentadiene petroleum resin or a hydrogenated cyclopentadiene petroleum resin and an inorganic filler.

The polyolefin used in the present invention is an ethylene-alpha-olefin copolymer resin, a low-density polyethylene resin or an ethylene-vinyl acetate copolymer resin. When the density is lower than 0.895, the flexibility of the film is too high to be suitable for the use of the porous film. When the density is higher than 0.940, the film is stiff and causes an undesirable feeling, The extrusion load is increased and the processing is difficult. When the molten resin is 5.0 or more, the uniformity of extrusion processing is lowered. Therefore, when the density is 0.895 to 0.940 and the melt index is 0.8 To 5.0 is used. As the? -Olefin of the ethylene -? - olefin copolymer resin, butene, hexene, and octene may be used. As the low-density polyethylene, those having a density of 0.900 to 0.935 and a melt index of 1.0 to 10.0, preferably 2.5 to 7.0 are used. The ethyene-vinyl acetate copolymer has a vinyl acetate content of 5% or more, a density of 0.910 to 0.940, and a melt index of 1.0 to 4.0.

In the blending of the polyolefin resin described above, when the blending amount of the low density polyethylene is large, the film workability is increased, but the physical properties of the tensile strength and elongation are lowered. If the blending amount of the ethylene-vinyl acetate copolymer resin is large, a certain amount helps the dispersibility of the inorganic filler, but if it exceeds this amount, it does not contribute to the increase of the dispersibility and causes deterioration of tensile strength and elongation properties.

In the present invention, the cyclopentadiene petroleum resin is obtained by reacting petroleum naphtha or the like with cyclopentadiene, a cyclopentadiene obtained by steam cracking or the like, a dimer thereof or an alkyl substituent thereof or a mixture thereof, Molecular sieve having a softening point of 160 ° C or higher and a high softening point of at least 160 ° C in an inert gas such as nitrogen gas at a high temperature of 215 ° C or more for several hours or more, The cyclopentadiene petroleum resin is used. The hydrogenated cyclopentadiene petroleum resin is obtained by a conventional method, that is, a hydrogenated cyclopentadiene petroleum resin having a softening point of 160 ° C or higher, obtained by hydrogenating a metal such as nickel or cobalt or an oxide thereof, Lt; / RTI > In addition, a mixture of the cyclopentadiene petroleum resin and the hydrogenated cyclopentadiene petroleum resin may be used.

The cyclopentadiene-based or hydrogenated cyclopentadiene petroleum resin used in the present invention has a softening point of 160 ° C or higher. When the softening point is not 160 ° C, the melt-mixing property with the polyolefin-based resin increases The tensile strength and elongation can be increased, but the required moisture permeability of the porous film is not effectively increased, and the object of the present invention can not be satisfied. A cyclopentadiene-based or hydrogenated cyclopentadiene petroleum resin having a softening point of 160 to 200 ° and an iodine value of 20 or less is preferable, because it is excellent in compatibility with the polyolefin used in the present invention.

The mixing ratio of the electric petroleum resin is 0.5 to 40 parts by weight, more preferably 2 to 30 parts by weight, based on 100 parts by weight of the polyolefin. If the amount is less than 0.5 part by weight, the composition can not meet the object of the present invention. If the amount is more than 40 parts by weight, the moisture permeability increases sharply at the same stretching ratio, but the mechanical properties of tensile strength, elongation and tear strength are not effectively increased, The film is stiff and the texture is not good.

In the present invention, inorganic fillers include calcium carbonate, silica, magnesium carbonate, barium sulfate, clay, talc, calcium oxide, titanium oxide, alumina, zeolite, potassium sulfate, barium carbonate or mixtures thereof, Barium is preferred. The inorganic filler may be any of those which have been surface-treated with stearic acid or the like by a known method and have an average particle diameter of 0.3 to 20 탆, preferably 0.5 to 4.0 탆. The blending amount of the inorganic filler is 20 to 100 parts by weight, preferably 40 to 80 parts by weight, per 100 parts by weight of the polyolefin resin. At this time, if the content is less than 20 parts by weight, the desired moisture permeability is not achieved as desired for the use of the porous film. If the content is more than 100 parts by weight, the tensile strength, the elongation and the tearing resistance are rapidly lowered.

In addition to the above-mentioned polyolefin resin, petroleum resin and inorganic filler, known resin additives may be used in the resin composition of the present invention. For example, phenolic or phosphorus antioxidants, processing stabilizers, and lubricants such as zinc stearate and metal stearate such as calcium stearate are used.

In order to prepare such a mixture of various compositions, each composition is put into a conventional tumbler or a henschell mixer, and then mixed using a twin-screw extruder, a kneader, a banbury mixer, A pellet-like compound is obtained by melt-processing mixing using a continuous mixer. At this time, the processing temperature should be in the range of 210 to 270 캜. In addition, when the petroleum resin and the polyolefin are preliminarily melted and mixed to make a masterbatch, and an inorganic filler is blended and melted and mixed by the above-mentioned method, the dispersed state of the petroleum resin is excellent and is very effective.

The resin composition of the thus-prepared porous film is extruded by a single screw extruder, cast on a casting roll through a die, cooled, and processed into a film. At this time, a die T_die, a fish tail die or a coat hanger die is used. The processed film immediately enters the stretching roll and is stretched in the longitudinal direction of the film. In this case, the preheating is preheated in a preheating roll having a preheating temperature of 30 to 70 DEG C before stretching, and the stretch ratio varies depending on the use of the porous film. When the stretching magnification is low, the mechanical properties such as tensile strength, elongation and tear strength However, the water vapor permeability decreases. On the contrary, when the stretching ratio is increased to 3.0 or more, the mechanical properties are rapidly lowered. Therefore, a magnification of 1.5 to 3.0 based on the linear velocity of the stretching roll is suitable. Such a porous film may also be produced by stretching in the longitudinal direction of the film and then stretching in the transverse direction of the film in a tenter equipped with a hot-air heating furnace.

In addition, the film processed by the composition of the present invention can be subjected to surface treatment with a corona or plasma treatment, depending on the intended use.

Hereinafter, the present invention will be described in more detail with reference to Examples.

It is to be understood by those skilled in the art that these embodiments are for describing the present invention only in detail and that the scope of the present invention is not limited to these embodiments.

Evaluation of physical properties in the following examples was carried out in the following manner.

(1) Tensile strength at break point, elongation: Tensile strength, elongation and tensile load were measured by taking specimens from longitudinal and transverse directions of a film prepared by the method of ASTM D882. The width of the measurement specimen was 25 mm, the grip interval was 50 mm, and the grip speed was 500 mm / min.

(2) Tear strength: Tensile strength was measured from the film prepared by the method of ASTM D1004 in the longitudinal direction of the film, and the tear strength was measured. The intergrip speed was 500 mm / min.

(3) Water vapor permeability: The water vapor permeability represents the amount of water that has passed through 24 hours per square meter of film in grams. About 50 grams of anhydrous calcium chloride was placed in an aluminum cup having a diameter of 12 cm and a depth of 1.5 cm and the film was placed thereon and sealed. The plate was allowed to stand for 2 hours in a constant temperature and humidity chamber at a temperature of 37.8 DEG C and a relative humidity of 90% The degree of hygroscopicity of calcium chloride caused by permeation of water was measured. The result of the 2-hour measurement was converted into 24 hours, and the area was also converted into 1 m2.

Examples 1 to 5

Of the polyolefin resins, the ethylene -? - olefin copolymer has a density of 0.917, a melt index of 2.1 and a comonomer of octene type, a low density polyethylene having a density of 0.925 and a melt index of 4.5, and ethylene- The coalescent used was 12% vinyl acetate comonomer and a melt index of 2.5. The cyclopentadiene petroleum resin having an iodine value of 12 and hydrogenated, and having a softening point of 172 占 폚 was used. The inorganic filler used was calcium carbonate surface-treated with stearic acid having an average particle diameter of 2.0 mu m.

Each of the above compositions was weighed in a predetermined amount as shown in the following Table 1, and 0.01 part by weight of a phenolic antioxidant IgGANOX-1010 (manufactured by Ciba Geigy Co., Ltd.), 10 parts by weight of a phosphorus antioxidant IgAphos-168 , Japan) and 0.01 part by weight of zinc stearate were each weighed, placed in a Henschel mixer, mixed for 5 minutes, and melt-extruded at 230 ° C by a twin-screw extruder to form a pelletized resin composition.

The electric resin composition was formed into a film by using a single screw extruder having a screw diameter of 60 mm and an apparatus having a die width of 800 mm. The cylinder temperature of the extruder was 225 deg. C, the die temperature was 220 deg. C, and the casting roll was cooled to 18 deg. C to produce a film. Then, the preheated film was again preheated at a temperature of 60 DEG C, and stretched in the longitudinal direction of the film by a roll stretching method to produce a porous film having a thickness of 35 microns (mu m). The stretching ratio at this time was 1.8 times as the ratio of the linear velocity of the stretching roll.

The tensile strength, elongation and mechanical properties of the tear strength and moisture permeability of the porous film thus prepared were measured (see Table 1)

Comparative Examples 1 to 3

The same ethylene /? - olefin copolymer, low density polyethylene, a polyolefin resin similar to ethylene-vinyl acetate and calcium carbonate used in Examples 1 to 5 and the mixing ratios of Table 1 were used in the same manner as in Examples 1 to 5 A resin composition was prepared and then stretched under the same conditions as in Examples 1 to 5 to prepare a porous film. The tensile strength at break, elongation, tear strength and moisture permeability of the thus-prepared porous film were measured and compared with the results of Examples 1 to 5 (see Table 1)

Table 1: Evaluation of physical properties of resin composition and porous film of porous film

[Table 1]

As shown in Table 1, the tensile strength, elongation and tear strength of the porous film prepared from the resin composition blended with the cyclopentadiene petroleum resin were higher than those of the resin compositions not containing the cyclopentadiene petroleum resin And the moisture permeability was remarkably increased.

Examples 6 and 7

The resin composition of the porous film was prepared by mixing to the same raw materials and blending ratios as those used in Examples 3 and 4, and the film was made into a film in the same manner as in Examples 3 and 4, and then stretched at a stretching ratio of 1.6 to obtain a porous film . The tensile strength, elongation, tear strength and moisture permeability of the thus-prepared porous film were measured (see Table 2)

Comparative Examples 4 and 5

The resin composition of the porous film was prepared by mixing with the same raw materials and mixing ratios as those used in Comparative Examples 2 and 3, and the film was made into a film in the same manner as in Examples 3 and 4, and then stretched at a stretching ratio of 1.6 to obtain a porous film . The tensile strength, elongation, tear strength and moisture permeability of the thus-prepared porous film were measured and compared with those of Examples 6 and 7 (see Table 2)

Table 2: Evaluation of physical properties of resin composition and porous film of porous film

[Table 2]

As shown in Table 2, the moisture permeability of the porous film having the stretching ratio of 1.6 without using the cyclopentadiene petroleum resin was significantly lower than that of the porous film having the stretch ratio of 1.8 (see Table 1) The porous film using the composition containing the cyclopentadiene-based petroleum resin has a lowered moisture permeability when the stretching ratio is lowered from 1.8 to 1.6, but the moisture permeability is still higher than the comparative example in which the cyclopentadiene- And the mechanical properties of tensile strength, elongation and tear strength were greatly increased.

Example 8

The resin composition of the porous film was prepared by mixing with the same raw materials and mixing ratios as those used in Example 4. The ethylene /? - olefin copolymer, the low density polyethylene resin and the cyclopentadiene petroleum resin were mixed at a blending ratio , The phenolic antioxidant, the phosphorus-based antioxidant and the zinc stearate used in Examples 1 to 5 were respectively weighed at the mixing ratios used in Examples 1 to 5 and then mixed in a henschell mixer for 5 minutes, And melt-mixed at 230 DEG C with a twin-screw extruder to obtain a masterbatch of the resin mixture on the pellet. The resin mixture of the prepared masterbatch and the calcium carbonate measured in the same mixing ratio as in Example 4 were put again in a Henschel mixer and mixed for 5 minutes and then melt-mixed at 230 DEG C with a twin-screw extruder to obtain a pellet-like compound. A film was prepared in the same manner as in Example 4 and stretched at the same stretching ratio to prepare a porous film. The tensile strength, elongation, tear strength and moisture permeability of the prepared film were measured (see Table 2)

As shown in Table 2, when the porous film is produced by masterbatching the resin composition of the porous film, the moisture permeability is not largely changed as compared with the case of not masterbatching, and the transverse tensile strength, elongation and longitudinal tear strength It was found that the mechanical properties were increased.

As described and demonstrated in detail above, the present invention is characterized in that the polyolefin resin comprises 100 parts by weight of a polyolefin resin, 0.5 to 40 parts by weight of a cyclopentadiene petroleum resin or hydrogenated cyclopentadiene petroleum resin and 20 to 100 parts by weight of an inorganic filler A resin composition for a film and a process for producing a porous film by melt-mixing the same, molding the film into a film, and stretching the film at least one or more axes. The porous film produced by the resin composition and the manufacturing method of the present invention is excellent in mechanical properties such as tensile strength, elongation and tearing strength, and is also excellent in the moisture permeability, so that the waterproof cover of the paper diaper passes through air and moisture, It can be used in various industrial applications such as clothing materials having characteristics that do not pass through, and building materials that prevent condensation of buildings.

Claims (9)

100 parts by weight of a polyolefin resin, 0.5 to 40 parts by weight of a cyclopentadiene-based petroleum resin or hydrogenated cyclopentadiene-based petroleum resin, and 20 to 100 parts by weight of an inorganic filler. The resin composition according to claim 1, wherein the polyolefin resin is at least one compound selected from the group consisting of an ethylene-alpha-olefin copolymer resin, a low-density polyethylene resin and an ethylene-vinyl acetate copolymer resin. The resin composition according to claim 1, wherein the cyclopentadiene petroleum resin or the hydrogenated cyclopentadiene petroleum resin has a softening point of 160 ° C or higher. The porous film according to claim 1, wherein the inorganic filler is calcium carbonate, silica, magnesium carbonate, barium sulfate, clay, talc, calcium oxide, titanium oxide, alumina, zeolite, potassium sulfate, barium carbonate, . The resin composition according to claim 1, wherein the inorganic filler has an average particle diameter of 0.3 to 20 占 퐉. The resin composition according to claim 2, wherein the ethylene -? - olefin copolymer resin is a copolymer resin having a melt index of 0.8 to 5.0 and a density of 0.895 to 0.940. The resin composition according to claim 2, wherein the low-density polyethylene resin is a resin having a melt index of 1.0 to 10.0 and a density of 0.900 to 0.935. The resin composition for a porous film according to claim 2, wherein the ethylene-vinyl acetate copolymer resin is a copolymer resin having a melt index of 1.0 to 4.0 and a density of 0.910 to 0.940. A process for producing a porous film, comprising the step of melt-mixing the resin composition of claim 1 to form a film, and stretching the film to at least one or more axes. ※ Note: It is disclosed by the contents of the first application.