JP3403842B2 - Soft polyolefin-based three-layer film. - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soft polyolefin-based three-layer film. 2. Description of the Related Art Conventionally, as a flexible film, a film obtained by blending a polyvinyl chloride resin with a large amount of a plasticizer, a stabilizer and the like has been generally used. However, a soft film made of a polyvinyl chloride resin has a problem in sanitary properties such as a plasticizer and a stabilizer. It has been pointed out that gas and the like are generated and do not decompose even when landfilled, thus polluting the environment. As an alternative to such a soft film made of a polyvinyl chloride resin, a soft film made of a polyolefin resin has been proposed. For example, (A) a composition comprising an amorphous polyolefin containing a propylene component (for example, 50% by weight or more) and crystalline polypropylene, and (B) at least three layers of crystalline polypropylene Polyolefin-based film, which has excellent flexibility, heat resistance, transparency, delamination strength (adhesion), low-temperature heat sealability, etc., and is comparable to polyvinyl chloride film It has been proposed as a composition of a flexible film made of a resin. However, for example, in the case of a co-extruded laminated film comprising a composition comprising an amorphous polyolefin containing a propylene component (for example, 50% by weight or more) and a crystalline polypropylene and a crystalline polypropylene, a film-forming property And there was a tendency that a good polyolefin-based soft film could not be stably obtained. Furthermore, the above composition tends to have a high melt flow rate, and other resins, particularly in a co-extruded laminated film with a polyethylene polymer, have a large difference in the melt flow rate with the polyethylene polymer, and In addition, the die swell ratio (thickness of the extruded product / extrusion die gap) was liable to fluctuate, and the resulting film and the like tended to have significantly reduced film thickness accuracy, interlayer adhesion strength, and the like. SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, the present invention provides a method for controlling the melt flow rate even when the moldability is poor at the time of extrusion film formation and a laminated film is formed. It is an object of the present invention to provide a soft polyolefin-based three-layer film having a composition in an intermediate layer, which is easy and reduces the variation in die swell ratio, thereby improving the film thickness accuracy and eliminating a decrease in interlayer adhesive strength and the like. The feature of the present invention is that (A) an amorphous polyolefin having a propylene and / or butene-1 component content of 50% by weight or more is 20 to 100%.
% By weight and (B) 80 to 0% by weight of crystalline polypropylene
To 97 to 80% by weight of the mixture containing (C)
3 to 20 low-crystalline ethylene-α-olefin copolymer
% By weight of a polyolefin resin composition as an intermediate layer, on both surfaces of which are selected from the group consisting of a polypropylene block copolymer containing propylene as a main component, a homopolypropylene, and a polypropylene random copolymer containing 3% by weight of ethylene. An object of the present invention is to provide a soft polyolefin-based three-layer film characterized by laminating any one type of polypropylene-based resin. The amorphous polyolefin (A) according to the present invention has a propylene and / or butene-1 content of 50% by weight or more, preferably 70 to 100% by weight, and more preferably 85 to 95% by weight. What is necessary is just a weight% of an amorphous olefin polymer. When the content of the propylene and / or butene-1 component of the amorphous polyolefin is less than 50% by weight, the compatibility with the crystalline polypropylene tends to decrease, which is not preferable. Further, the above-mentioned amorphous polyolefin preferably has a boiling n-heptane insoluble content of 70% by weight or less, preferably 50% by weight or less and 10% by weight or more. When the boiling n-heptane insoluble content exceeds 70% by weight,
A film obtained by reducing the ratio of the amorphous portion is poor in flexibility and tends to fail to obtain a polyolefin-based soft film, which is not preferable. Further, the amorphous polyolefin preferably has a number average molecular weight of 1,
000-200,000, more preferably 1,500-
100,000 can be exemplified. Number average molecular weight 200,
If it exceeds 000, it is difficult to form a film,
If it is less than 10, the mechanical strength (tensile elongation, etc.) tends to decrease, which is not preferable. The amorphous polyolefin of the present invention may be used alone or in combination of two or more, and there is no particular limitation. As the above-mentioned amorphous polyolefin according to the present invention, specifically, in the case of an amorphous polyolefin having a propylene component as a main component, polypropylene,
Propylene / ethylene copolymer, propylene / butene
1 copolymer, propylene / butene-1 / ethylene terpolymer, propylene / hexene-1 / octene-1
And the like. When the above-mentioned amorphous polyolefin is an amorphous polyolefin having a butene-1 component as a main component, polybutene-1, butene-1 · ethylene copolymer, butene-1 · propylene Copolymer, butene-1
・ Propylene / ethylene terpolymer, butene-1
Hexene-1 / octene-1-3 terpolymer, butene-
1-hexene-1,4-methylpentene-1-terpolymer and the like. The crystalline polypropylene (B) according to the present invention may be a general polypropylene which is usually used for extrusion molding, blow molding and the like, and examples thereof include boiling n-heptane insoluble isotactic polypropylene. The crystalline polypropylene may be a propylene homopolymer or a copolymer of isotactic polypropylene having stereoregularity and another α-olefin, and is not particularly limited. At this time, the α-olefin has 2 to 2 carbon atoms.
6, α-olefins such as ethylene, butene-1,
Examples thereof include pentene-1, hexene-1, heptene-1, and octene-1, and there is no particular limitation, but ethylene or butene-1 is preferred. More specifically, as a homopolymer of polypropylene or a copolymer of isotactic polypropylene and ethylene, a propylene / ethylene containing 50% by weight or less, preferably 20 to 1.0% by weight of an ethylene component is used. The random copolymer or the block copolymer is a copolymer of isotactic polypropylene and butene-1 and contains butene-1 in an amount of 50% by weight or less, preferably 20% by weight or less.
Examples thereof include a random copolymer or block copolymer of propylene / butene-1 containing 1.0 to 1.0% by weight. The crystalline polypropylene may be used alone or in combination of two or more, and there is no particular limitation. The mixture according to the present invention comprising (A) an amorphous polyolefin and (B) a crystalline polypropylene,
The amorphous polyolefin described above alone or 20 to 100% by weight of the amorphous polyolefin, preferably 30 to 100% by weight.
It can be obtained by being blended so as to be 100% by weight.
If the amount of the amorphous polyolefin is less than 20% by weight, sufficient flexibility cannot be imparted, and a flexible film cannot be obtained. Further, the composition according to the present invention is obtained by uniformly mixing (C) a low-crystalline ethylene-α-olefin copolymer with a mixture comprising (A) an amorphous polyolefin and (B) a crystalline polypropylene. The compounded one is preferable. (C) The compounding amount of the low-crystalline ethylene-α-olefin copolymer is as follows:
With respect to 80 to 97% by weight of the composite comprising (A) amorphous polyolefin and (B) crystalline polypropylene, 2
It is preferable to add 0 to 3% by weight. If the amount of the low-crystalline ethylene-α-olefin copolymer exceeds 20% by weight, the heat resistance of the polyolefin-based film comprising the composition of the present invention tends to decrease, which is not preferable. If the amount of the low-crystalline ethylene-α-olefin copolymer is less than 3% by weight, it is difficult to control the melt flow rate during extrusion molding and the like, and the die swell ratio during film formation varies. It is not preferable because it is not easy to prevent a decrease in film thickness accuracy, and when a laminated film is formed, an improvement in the delamination strength of the laminated film cannot be expected. The low-crystalline ethylene-α-olefin copolymer has a crystallinity of 3 to 20% and an ethylene content of 85.
~ 95 mol%, density 0.86-0.91, MI (190
° C) 0.1-40, melting point (measured by DSC) 60-90 ° C
Ethylene-butene-1-random amorphous or low-crystalline ethylene-propylene random copolymer having a melting point of 60 to 90 ° C. and an ethylene content of 8
A preferred example is 5-95 mol% of an ethylene-butene-1-random copolymer. At this time, the crystallinity was a value obtained by X-ray diffraction measurement having a crystal peak at the diffraction position on the [100] plane, and dividing the peak area by the entire intensity. This is a value determined based on the peak position. Low-crystalline ethylene-α-olefin copolymer in these ranges,
It has excellent compatibility with polyolefins and tends to improve the flexibility, impact resistance, heat sealability, transparency, etc. of polyolefin resins, etc., and can give excellent film thickness accuracy (appearance) to films. . The polyolefin resin composition according to the present invention may further contain various additives and fillers, if desired, such as heat stabilizers, antioxidants, light stabilizers, antistatic agents, and the like.
Lubricants, nucleating agents, twisting agents, pigments or dyes, calcium carbonate, barium sulfate, magnesium hydroxide, mica, talc, clay and the like can be added. Further, other thermoplastic resins, thermoplastic elastomers and the like may be blended as necessary. The method for producing a polyolefin resin composition according to the present invention comprises: (A) 20 to 100% by weight of an amorphous polyolefin having a propylene and / or butene-1 component content of 50% by weight or more; B) 80 to 0% by weight of a crystalline polypropylene and, if necessary, other additives are heated and melted and kneaded. The kneading can be exemplified to be carried out at a temperature at which each of the above components melts, usually at 180 to 250 ° C. for about 30 minutes. Melt kneading is performed by an appropriate known method,
For example, using a kneader such as a pressure kneader, a Banbury mixer, or a roll, a single-screw or twin-screw extruder, for example,
Granulation into pellets can be performed. Next, 80 to 9 of the mixture obtained above
20% to 3% by weight of (C) a low crystalline ethylene-α-olefin copolymer is uniformly blended with 7% by weight. As a method of uniformly blending, after mixing the pellets of the composition obtained above and the pellets of the low-crystalline ethylene-α-olefin copolymer with a Hensiel mixer, a ribbon blender, and the like, Examples of the method include melt kneading with a twin-screw extruder, a Banbury mixer, a pressure kneader, and the like. Further, the composition of the present invention comprises (A) propylene and / or
Or an amorphous polyolefin having a butene-1 component content of 50% by weight or more, (B) a crystalline polypropylene, and (C)
A method in which the low-crystalline ethylene-α-olefin copolymer is mixed with a Henschel mixer, a ribbon blender, or the like, and then melt-kneaded with a single- or twin-screw extruder, a Banbury mixer, a pressure kneader, or the like. Since the polyolefin resin composition according to the present invention has improved compatibility, heat resistance, moldability, etc., the composition is used as an intermediate layer, and a polypropylene block containing propylene as a main component on both surfaces thereof. A three-layer film obtained by laminating any one type of polypropylene resin selected from the group consisting of a copolymer, homopolypropylene, and a polypropylene random copolymer containing 3% by weight of ethylene has flexibility, delamination strength (adhesion). This results in excellent film thickness accuracy. The use of the present invention includes various uses, for example, food packaging, textile packaging, medical use, industrial material use, and the like. According to the present invention, a specified amount of a mixture of a specified amount of an amorphous polyolefin containing a specified amount of propylene and / or a butene-1 component and a specified amount of crystalline polypropylene, Is a three-layer film comprising, as an intermediate layer, a polyolefin-based resin composition obtained by uniformly blending the low-crystalline ethylene-α-olefin copolymer described above. This makes it easy to control the melt flow rate even when forming a laminated film and poor moldability at the time of extrusion film formation, reduces the die swell ratio, and improves the film thickness accuracy at the time of molding. It is possible to provide a flexible film made of a polyolefin-based resin having excellent flexibility and the like, in which a decrease in interlayer adhesion strength and the like of the laminated film is eliminated. The present invention will be described below in more detail with reference to examples. However, it goes without saying that the present invention is not limited to only the following examples. At this time, each inspection item in the following examples of the present invention was measured by the following method. [Film thickness accuracy (μ)]: Difference in thickness in the width direction. [Peeling strength (kg / cm)]: After two films were laminated and heat-sealed at 180 ° C., a 15 mm wide test piece was prepared, and the 180 ° peel strength was measured and evaluated. Example 1 [Preparation of Composition] (A) Density 0.86 g / cm ³ , propylene content 65
Wt%, butene-1 content 35 wt%, melt viscosity 10,
000 cps (190 ° C.), 50% by weight of amorphous polyolefin resin, (B) density 0.90 g / cm ³ , melt flow rate (MFR) (230 ° C.) 1.0 g / 10
min. Was mixed and melt-kneaded and granulated at 230 ° C. for 30 minutes to obtain pellets. 95% by weight of the pellets obtained above were added to (C) a density of 0.88 g / cm3 and a melt flow rate (MFR).
(190 ° C.) 3.6 g / 10 min. And 5% by weight of a low-crystalline ethylene-butene-1-random copolymer having an ethylene content of 90 mol% were uniformly blended. The obtained compound was melt-kneaded with an extruder having a twin screw heated to 230 ° C., and then granulated to produce a pellet composition. {Forming of Laminated Film} The composition prepared above was added to the layer (a) and the density was 0.9.
g / cm ³ , melt flow rate (MFR) (230
C) 8.2 g / 10 min. A polypropylene-based block copolymer having a melting point of 161 ° C. was used for the layer (b).
The three-layer laminated film of (b) / (a) / (b) was made to have the thickness shown in Table 1, and three independent extruders were used for each of the three layers and a three-layer T die connected thereto. And melt-extruded into three layers while adjusting the thickness. Subsequently, the laminated film shown in Table 1 was obtained while cooling with an air knife and a cooling roll having a surface temperature of 40 ° C. Table 2 shows the thickness difference in the width direction of the laminated film and the peel strength between the (a) layer and the (b) layer. Example 2 The density of 0.9 g / cm ³ and the melt flow rate (MFR) (230 ° C.) of 13.0 g / 10 min. ,
A laminated film having the structure shown in Table 1 was obtained in the same manner as in Example 1 except that a homopolypropylene resin having a melting point of 161 ° C. was used. Table 2 shows the thickness difference in the width direction of the laminated film and the peel strength between the (a) layer and the (b) layer. Example 3 A layer (b) having a density of 0.90 g / cm ³ and a melt flow rate (MFR) (230 ° C.) of 9.0 g / 10 min. ,
A laminated film having the structure shown in Table 1 was obtained in the same manner as in Example 1 except that the ethylene-propylene random copolymer having a melting point of 142 ° C. and an ethylene content of 3% by weight was used. Table 2 shows the thickness difference in the width direction of the laminated film and the peel strength between the (a) layer and the (b) layer. Comparative Example 1 The composition was (A) an amorphous material having a density of 0.86 g / cm ³ , a propylene content of 65% by weight, a butene-1 content of 35% by weight, and a melt viscosity of 10,000 cps (190 ° C.). 50% by weight of polyolefin resin and (B) density of 0.90 g / c
m ³ , melt flow rate (MFR) (230 ° C.)
0 g / 10 min. Crystalline polypropylene resin 50
% Of the mixture and melt-kneaded and granulated at 230 ° C. for 30 minutes to obtain a laminated film having the structure shown in Table 1 in the same manner as in Example 1. Table 2 shows the thickness difference in the width direction of the laminated film and the peel strength between the (a) layer and the (b) layer.
Shown in Comparative Example 2 The composition was (A) an amorphous material having a density of 0.86 g / cm ³ , a propylene content of 65% by weight, a butene-1 content of 35% by weight, and a melt viscosity of 10,000 cps (190 ° C.). 50% by weight of polyolefin resin and (B) density of 0.90 g / c
m ³ , melt flow rate (MFR) (230 ° C.)
0 g / 10 min. Crystalline polypropylene resin 50
Wt.%, Melt-kneaded and granulated at 230 ° C. for 30 minutes, and the layer (b) has a density of 0.9 g / cm.
^3. Melt flow rate (MFR) (230 ° C)
0 g / 10 min. A laminated film having the structure shown in Table 1 was obtained in the same manner as in Example 1 except that the resin was a homopolypropylene resin having a melting point of 161 ° C. Table 2 shows the thickness difference in the width direction of the laminated film and the peel strength between the (a) layer and the (b) layer. Comparative Example 3 The composition was (A) an amorphous material having a density of 0.86 g / cm ³ , a propylene content of 65% by weight, a butene-1 content of 35% by weight, and a melt viscosity of 10,000 cps (190 ° C.). 50% by weight of polyolefin resin and (B) density of 0.90 g / c
m ³ , melt flow rate (MFR) (230 ° C.)
0 g / 10 min. Crystalline polypropylene resin 50
Wt.%, Melt kneaded and granulated at 230 ° C. for 30 minutes, and the layer (b) has a density of 0.90 g /
cm ³ , melt flow rate (MFR) (230 ° C)
9.0 g / 10 min. A laminated film having the structure shown in Table 1 was obtained in the same manner as in Example 1 except that the ethylene-polypropylene random copolymer having a melting point of 142 ° C. and an ethylene content of 3% by weight was used. Table 2 shows the thickness difference in the width direction of the laminated film and the peel strength between the (a) layer and the (b) layer.
Shown in Comparative Example 4 The composition was (A) an amorphous material having a density of 0.86 g / cm ³ , a propylene content of 65% by weight, a butene-1 content of 35% by weight, and a melt viscosity of 10,000 cps (190 ° C.). 50% by weight of polyolefin resin and (B) density of 0.90 g / c
m ³ , melt flow rate (MFR) (230 ° C.)
0 g / 10 min. Crystalline polypropylene resin 50
Wt.%, Melt kneaded and granulated at 230 ° C. for 30 minutes, and (b) layer has a density of 0.92 g /
cm ³ , melt flow rate (MFR) (190 ° C.)
4.0 g / 10 min. A laminated film having the configuration shown in Table 1 was obtained in the same manner as in Example 1 except that the low-density polyethylene (LDPE) having a melting point of 110 ° C. was used. Table 2 shows the thickness difference in the width direction of the laminated film and the peel strength between the (a) layer and the (b) layer. [Table 1] [Table 2] The film obtained by melt-extruding the composition of the present invention is a film having a small variation in the die swell ratio during the melt extrusion, a small variation in the film thickness and an excellent film thickness accuracy. is there. Moreover, the film is excellent in flexibility, heat resistance and the like. Furthermore, when a laminated film is formed, even a film (for example, a polyolefin-based resin) that requires an adhesive layer to be interposed due to poor adhesiveness, when laminated with a layer composed of the composition of the present invention, A laminated film having excellent adhesive strength can be obtained without an adhesive layer. In addition, films (including laminated films) comprising the composition of the present invention can be used for various packaging materials, for example, packaging films for food packaging, textile packaging, medical use, industrial materials, and the like. Can be illustrated.

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁷ identification code FI (C08L 23/20 23:08) (58) Investigated field (Int.Cl. ⁷ , DB name) C08L 23/00-23 / 36 B32B 27/00-27/42

Claims (1)

(57) [Claims] (1) Propylene and / or butene-1
Amorphous polyolefin 2 having a component content of 50% by weight or more
0 to 100% by weight and (B) crystalline polypropylene 80 to
(C) low-crystalline ethylene-α-olefin copolymer in 80 to 97% by weight of the mixture containing 0% by weight.
A polyolefin-based resin composition containing 0 to 3% by weight is selected as an intermediate layer, and a polypropylene block copolymer containing propylene as a main component, a homopolypropylene, and a polypropylene random copolymer containing 3% by weight of ethylene on both surfaces thereof. A soft polyolefin-based three-layer film, characterized in that any one of the above-mentioned polypropylene-based resins is laminated.