KR100557566B1 - Polyolefin resin composition having matt property and method for forming film using the same - Google Patents

Abstract

The present invention relates to a polyolefin resin composition excellent in matt properties, impact strength and tear strength and a method for producing a film using the same, more specifically, the melt index (ASTM D1238, MI) is 0.01 as the first component Ethylene-alpha olefin copolymer resin or ethylene polymer resin 50-70% by weight, the second component having a density of 0.930 g / cm ³ or more and a carbon number of 10 or less alpha olefin and ethylene 0-12 wt% of an ethylene-propylene copolymer containing 30-70 wt% of ethylene with a melt index of 0.1-0.5 g / 10 min, and a melt index of 1.0-3.0 g / 10 min, 10 wt. Less than% of a copolymer mixture of ethylene and propylene of 18 to 50% by weight, wherein the mixture of the second and third components has a MI of less than 1.0 and a content of 30 to 50% by weight of the total composition. And compositions blown The method relates to a method of molding into a film.

Matte, Polyolefin, Resin Composition, Film, Blown

Description

Polyolefin resin composition having matt properties and film forming method using the same {Polyolefin resin composition having matt property and method for forming film using the same}

The present invention relates to a polyolefin resin composition having excellent matting properties, impact strength and tear strength, and a molding method of a film using the same, and more particularly, to a polypropylene resin and a commercially available resin having incompatibility with a polyethylene-based resin. The present invention relates to a polyolefin resin composition having a matte property and having excellent impact strength and tear strength, using a single layer structure or a multilayer structure film formed / blown by a blown film manufacturing method, and having excellent impact strength and tear strength.

Polyolefin is a balanced resin in terms of price and performance. Film made of polyolefin resin has excellent mechanical, thermal, and electrical properties, and has excellent chemical resistance and moldability. It is a coating material for other materials such as food packaging, product packaging, and paper. It is the most used worldwide. Among them, matte film is widely used as a high value-added product by reducing the surface gloss of the film to give a soft touch to the film, thereby increasing the commerciality of the packaged material.

Matte phenomena are caused by poor reflection phenomena due to irregularities of the reflective surface. Methods of imparting matte properties to the surface include: 1) surface treatment of general film surfaces by coating and etching, and 2) non-compatibility. Characteristic of the resin mixture, there is a method using the flowability, shrinkage and refractive index difference between the mixed resin, 3) a method of imparting concavities and convexities on the surface by using an inorganic material, and 4) an embossing method to give the concavities and convexities to the cooling roll.

In general, the first method requires a separate post-processing equipment such as coating and drying equipment and is not well used. Commercially, the second method, the third method, the fourth method, or a mixture thereof is used.

The method for producing a polyolefin film includes a casting method using a straight die (T-die) and a blown film method using a round die. Among them, the blown film method is the most widely used method because the manufacturing facilities are inexpensive and the balance of tear strength is good and the impact strength and tear strength are excellent. However, since the blown film method is a method of manufacturing a film through stretching of the bubble, there is a limit that the bubble stability of the resin to be used is more than a predetermined level. The method of imparting matte properties to the surface by using the second method is largely due to the difference in flowability between the mixed resins. In general, the larger the difference in the MI (Melt Index, ASTM D1238) of the mixed resins, the higher the MI. Resin blended). For this reason matte films have been produced using casting methods.

US Pat. No. 5,560,885 describes resin compositions and molding techniques having matt properties using polyolefin mixtures. According to the contents disclosed in the patent, incompatible ethylene-alpha olefin copolymers and propylene-alpha olefin copolymers or their ter-polymer blends are used, and the processing method is biaxial stretching after sheet production by casting. The stretching temperature is 40 to 100 ° C and the stretching ratio is 32 to 70 times. MI of the resin used is 1.5 g / min-12 g / min, and it is described that between 2.5 and 6 g / min is preferable.

According to US Pat. No. 5,473,016, a technique relating to a resin composition capable of producing a film or sheet having a matte property is disclosed. The resin mixture comprises 1) 10-80% of a polyolefin copolymer having a MI of 1-20 g / min, 2) 5-30% of a super low density ethylene-alphaolefin copolymer having a density of 0.86-0.91 g / cm ³ , and 3) MI Is 5 to 85% of a modified polyolefin resin having a value of 0.1 to 2.0 g / 10 min.

As described above, the film produced by the casting method has a disadvantage of weak tear strength and impact strength due to uniaxial or biaxial stretching effects, and has a disadvantage in that the process is complicated and the initial investment costs are high. In addition, the film produced by casting has a disadvantage that a second sealing process is required when manufacturing a packaging bag such as a shopping bag.

U. S. Patent No. 3,361, 704 discloses a method of adding matte to a polyolefin film by adding an inorganic material. As in the above patent, when 30-80% of inorganic material is added, physical properties of the inorganic material are not compatible with the resin, and thus tearing, tensile, impact strength, etc. are reduced, and a separate compounding device for mixing the inorganic material There is a disadvantage that it is necessary.

 Accordingly, an object of the present invention is to provide a polyolefin resin composition excellent in matt properties, impact strength and tear strength.

Another object of the present invention is to use the blown film method, which is different from the above-described conventional technology, to provide excellent physical properties such as impact strength and tear strength, and to provide simple and inexpensive equipment. The present invention also provides a method for forming a polyolefin film having excellent properties.

The composition of the present invention for achieving the above object is an alpha olefin having a melt index (ASTM D1238, MI) of 0.01 ^~ 0.4g / 10min, a density of 0.930g / cm ³ or more, carbon number 10 or less as a first component; Ethylene-alpha olefin copolymer resin or copolymer of ethylene or ethylene-propylene containing 50 to 70% by weight of ethylene polymerized resin and a melt index of 0.1 to 0.5g / 10min as a second component and 30 to 70% by weight of ethylene 0-12 weight% of a copolymer, and a melt index of 1.0-3.0 g / 10min as a 3rd component, and 18 to 50 weight% of a copolymer mixture of ethylene and propylene of less than 10 weight%, Comprising: The said 2nd component The mixture of components and the third component has a MI of less than 1.0 and a content of 30 to 50% by weight of the total composition.

The molding method of the present invention for achieving another object of the present invention is a single layer or through a blown film method of the temperature of the resin extruded from the die is 180 ~ 250 ℃, BUR (Blow Up Ratio) of the bubble 0.9 ~ 3.0 It consists of shape | molding the said resin composition into a film in multilayer.

Looking at the present invention in more detail as follows.

The composition of the present invention has a melt index (ASTM D1238, MI) of 0.01 to 0.4 g / 10 min, a density of 0.930 g / cm ³ or more, and a copolymer of alpha olefin and ethylene having 10 or less carbon atoms as the first component, ethylene. -50 to 70% by weight of alpha olefin copolymer resin is used. At this time, if the melt index of the ethylene-alpha olefin copolymer resin or the ethylene polymer resin, which is the first component, is less than 0.01 g / 10 min, the viscosity of the resin is too high, resulting in problems in kneading property, and thus it is difficult to obtain a uniform matt effect. If exceeded, the total MI of the resin is increased and the bubble stability of the resin tends to be impaired. If the density is less than 0.930 g / cm ^3, the shrinkage of the resin is small, thereby not giving a matt effect. In addition, when the amount of the ethylene-alpha olefin copolymer resin or ethylene polymerized resin used as the first component is less than 50% by weight, it may not form a matrix, resulting in deterioration of film properties, and when it exceeds 70% by weight, one component becomes excessive. Accordingly, surface irregularities tend to be reduced, thereby reducing the matte properties of the film.

As a second component of the composition according to the present invention, a melt index of 0.1 to 0.5 g / 10 min, and 0 to 12 wt% of an ethylene-propylene copolymer containing 30 to 70 wt% of ethylene is used. At this time, if the melt index of the ethylene-propylene copolymer is less than 0.1g / 10min, there is a problem in kneading due to the viscosity problem, if it exceeds 0.5g / 10min, the phase becomes smaller during the kneading process, the matte properties are reduced, and the amount of ethylene is 30 If less than or more than 70% by weight, the crystallinity of the resin is increased, and the export rate is similar when cooling with other components, thereby reducing the surface irregularities, thereby reducing the matte properties of the film. In addition, when the amount of the ethylene-propylene copolymer used as the second component exceeds 12% by weight, the content of the amorphous resin increases, the rigidity of the film decreases, the film becomes transparent, and the matting property tends to decrease.

As the third component of the composition according to the present invention, the melt index is 1.0 to 3.0 g / 10 min, and less than 10% by weight of 18 to 50% by weight of a copolymer mixture of ethylene and propylene is used. At this time, when the melt index of the ethylene propylene copolymer resin is less than 1.0 g / 10 min, the flowability difference with the resin of the first component is reduced, and the matte property is reduced. When the melt index of the ethylene copolymer copolymer is less than 3.0 g / 10 min, the bubble stability is deteriorated. If the content is 10% by weight or more, the crystallinity is lowered and the matte property is also reduced. In addition, when the amount of the copolymer mixture of ethylene and propylene which is the third component is less than 18% by weight, the surface unevenness tends to decrease as the first component is excessive, thereby reducing the matte property of the film. The first component does not form a matrix, resulting in a decrease in film properties.

Therefore, the mixture of the second component and the third component preferably has a MI of less than 1.0, and the content of the total composition is preferably 30 to 50% by weight.

In addition, in order to control the visual touch of the surface of the matte film to the composition, it can be added to less than 300ppm with a peroxide (fourth component), if the amount exceeds 300ppm odor due to unreacted peroxide And foreign matters are more likely to occur, and the crosslinking reaction of the first component may be excessive.

At this time, the resin mixture is composed of a matrix phase of the first component, which is a very low ethylene-alpha olefin copolymer resin, and a copolymer mixture of ethylene and propylene. To achieve this, the second component serves to help the compatibility of the two phases. That is, the first component improves / maintains the bubble stability of the resin mixture as the matrix, and the third component gives the unevenness on the surface of the film by the difference in refractive index / flow / shrinkage with the matrix. The component acts as a compatibilizer of the first component and the third component to compensate for the reduction in tear strength and impact strength, which is a general disadvantage of the phase separated resin. In this case, the second component and the third component may use impact polypropylene prepared beforehand in the form of a mixture in a single process during resin polymerization.

The fourth component, peroxide, which is optionally added, acts as a compatibilizer for polyethylene and polypropylene to reduce the size of the phase-separated resin phase, thereby providing a soft touch visual characteristic.

Molding equipment and conditions for producing a matte film using the composition is a blower film molding machine for producing single or multilayer polyolefin film commercially available, the temperature of the resin extruded from the die is 180 ~ 250 ℃ is preferable, and the BUR (Blow Up Ratio) of the bubbles is preferably 0.9 to 3.0. When manufacturing a film in a multilayer, the resin composition of this invention is used as a surface layer.

In the present invention, a blown film forming apparatus for producing a polyolefin film means a blown film apparatus for manufacturing a film such as high density / medium density / (linear) low density polyethylene, polyethylene vinyl acetate resin, and the like. If the temperature of the resin extruded from the die is less than 180 ℃, melt fracture occurs on the surface of the film, so that the surface of the film is not multiplied. If the temperature exceeds 250 ℃, the bubble stability becomes low, making it impossible to form a uniform film. do. The higher the BUR of the bubble, the better the balance between the physical properties of the film in the machine direction and the resin direction. However, if the BUR exceeds 3.0, the BUR deteriorates the stability of the bubble.

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 thereto.

Examples 1-8

To obtain a polyolefin resin composition of the present invention in the components and amounts shown in Table 1 below, the resin composition was kneaded at 200 ~ 240 ℃ using a 30ψ twin screw compounder, low density polyethylene blown film forming machine To prepare a matte film (die temperature = 200 ℃, BUR = 1.6). The matte properties, impact strength and bubble stability of the films prepared in Examples 1 to 8 were measured and shown in Table 1 below. Matte properties, impact strength and bubble stability are measured as follows.

Gloss: When the light is shined on the test material at a certain angle (60 °) and the reflected light is received at the same angle as the incident light, the intensity of the light is set to 100 on the glass surface with a refractive index of 1.567. It is expressed as a value (%).

Impact strength: In the method of measuring the impact strength of the film, Spencer impact strength was used in the present invention. At this time, the weight is 30kg and the diameter of hemispherical weight is 0.5 ^〃 .

Bubble Stability: Evaluated by the degree of shaking of bubbles during film forming and the dimensional (thickness and width) stability of the molded film.

No vibration of phase-bubble and stable dimension.

Medium-bubble tremors, but dimensions remain stable.

Due to the tremor of lower bubble, there is no dimensional stability.

Examples and Comparative Examples Composition ratio (% by weight) Matte Gloss (%)  Impact strength  Bubble stability First ingredient Second ingredient Third ingredient Fourth ingredient  Example 1    60% ρ = 0.956 MI = 0.047 2.4% C ₂ = 55% MI = 0.2 37.6% C ₂ = 0% MI = 0.7  -  6.5 (up)  Prize  Prize  Example 2    60% ρ = 0.956 MI = 0.047 2.4% C ₂ = 55% MI = 0.2 37.6% C ₂ = 0% MI = 0.7  200 ppm  5.0 (upper)  Prize  Prize  Example 3    60% ρ = 0.944 MI = 0.22 2.4% C₂ = 55% MI = 0.2 37.6% C ₂ = 0% MI = 0.7  -  10.5 (Medium)  Prize  medium  Example 4    60% ρ = 0.930 MI = 0.36 2.4% C ₂ = 55% MI = 0.2 37.6% C ₂ = 0% MI = 0.7  200 ppm  10.8 (medium)  medium  medium  Comparative Example 1    60% ρ = 0.920 MI = 1.0 2.4% C ₂ = 55% MI = 0.2 37.6% C ₂ = 0% MI = 0.7  200 ppm  20.0 (lower)  Ha  Ha  Example 5    50% ρ = 0.941 MI = 0.33 50% C ₂ = 5.9% MI = 0.5  -  9.3 (medium)  medium  medium  Comparative Example 2    50% ρ = 0.941 MI = 0.33 50% C ₂ = 2.0% MI = 1.8  -  8.8 (medium)  Ha  Ha  Comparative Example 3    50% ρ = 0.941 MI = 0.33 50% C ₂ = 8.0% MI = 3.5  -  15.5 (Lower)  Ha  Ha

Note) p is the density (g / cm 3) and C ₂ is the ethylene content.

In the case of the first component in Table 1,% is the content relative to the whole, Examples 1 and 2 are ethylene homo polymers, the rest is ethylene / butene-1 copolymer.

As can be seen in Examples 1 and 2 of Table 1, the addition of the peroxide was found to improve the matte properties of the film, in Examples 3 and 4 the density of the first component is reduced to the matte properties It was lowered, the MI was increased, the bubble stability was shown, but it was usable level. In Comparative Example 1, the MI of the first component was not high, so there was no sufficient bubble stability for film molding, and the matt of the first component was greater than that of the second and third components. Example 5 and Comparative Examples 2 and 3 used the second component and the third component as one impact polypropylene, the results of Example 5 were similar to Example 4, the results of Comparative Examples 2 and 3 are Comparative Examples Similar to 1.

Claims (4)

Ethylene-alpha olefin copolymer resins or ethylene polymer resins having a melt index (ASTM D1238, MI) of 0.01 to 0.4 g / 10 min and a density of 0.930 g / cm ³ or more and 10 or less alpha olefins having 10 or less carbon olefins. 70% by weight, 0-12% by weight of an ethylene-propylene copolymer having a melt index of 0.1-0.5 g / 10min as a second component and containing 30-70% by weight of ethylene, and The third component has a melt index of 1.0 to 3.0 g / 10 min and comprises less than 10% by weight of 18 to 50% by weight of a copolymer mixture of ethylene and propylene, Here, the mixture of the second component and the third component has a MI of less than 1.0, the content of the total composition is a polyolefin resin composition having a matte characteristics, characterized in that consisting of 30 to 50% by weight. The polyolefin resin composition of claim 1, wherein the composition further comprises a peroxide of 300 ppm or less. The resin composition extruded from the die has a temperature of 180 to 250 ° C. and a blow up ratio (BUR) of 0.9 to 3.0, and the resin composition according to claim 1 or 2 is filmed through a blown film method. How to mold The method according to claim 3, wherein when the multilayer film is molded, at least one layer of the resin composition is formed on the surface layer.