JPS63218749A - Polyethylene resin composition for extensible film - Google Patents

Abstract

PURPOSE:To obtain the titled composition having high extensibility, capable of being stuck fast to a mold of original form in vacuum in the use of sand mold for casting, by blending a specific copolymer of ethylene and an alpha-olefin with specific amounts of a linear low-density polyethylene and a plasticizer. CONSTITUTION:(A) 100pts.wt. copolymer of ethylene and >=3C alpha-olefin (e.g. propylene, etc.) having <=2g/10min melt index, <=0.91g/cm<3> density and <=30 flow ratio is blended with (B) <=70pts.wt., preferably 10-60pts.wt. linear low- density polyethylene having <=10g/10min melt index, >=500% elongation, <=0.935g/cm<3> density and 10-70 flow ratio and (C) 0.1-20pts.wt., preferably 0.2-10pts.wt. plasticizer (e.g. dimethyl phthalate, etc.).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a polyethylene resin composition for use in stretchable films. More specifically, the present invention relates to a polyethylene resin composition for stretchable films that uses a copolymer of ethylene and α-ole7·yne having 3 or more carbon atoms and has excellent stretching properties.

[Prior art]

Conventionally, casting pots (sand molds) used in casting have been made strong by tamping the sand that makes up the mold, and the shape of the mold is maintained by the strength of the mold itself. In recent years, a method has been proposed in which the shape of the mold is maintained by covering the surface of the mold with a synthetic resin film.

That is, in FIGS. 7 to 7, the thermoplastic resin film 3 is vacuum-adhered to the molding surface λ of the original matrix while heating, and the film 3 is vacuum-formed into the same shape as the matrix, Next, a frame is brought into contact with the film 3 on the molding surface from both sides, and the frame is filled with particulate matter, such as sand, and the air inside the frame is evacuated to create a negative pressure (reduced pressure). ) Then, the film is pulled toward the frame side by K, and a mold is obtained in which the shape of the film is maintained in the molded shape of the original matrix even after it is removed from the original matrix. It will be done. This mold casting method is hereinafter abbreviated as the V-process.

The typical thermoplastic resin film used for the V-process described above was an ethylene-vinyl acetate copolymer.

[Problem that the invention seeks to solve]

In the above-mentioned V-process, the thermoplastic resin film is heated to soften it and vacuum-adhered to the master mold, so film heating equipment is required. To maintain this, the wall must be thick. Therefore, it cannot be said to be economically advantageous in terms of film cost and heating equipment.

[Means for solving problems]

In view of the above situation, the present inventors, in the ■-process,
A copolymer of ethylene and an α-olefin having 3 or more carbon atoms, which has specific physical properties, is blended with a specific amount of linear low-density polyethylene and a plasticizer, resulting in a layered product that can be vacuum-adhered without additional softening. When a resin composition is used to form a film, the resulting film has high extensibility and sufficient mechanical strength even beyond the elasticity limit. -1. When used in the V- process, the present invention was completed based on the discovery that vacuum adhesion to the master mold can be achieved without heating and softening.

That is, the narrow gist of the present invention is that the melt index is -177
A copolymer of ethylene and an α-olefin having 3 or more carbon atoms lθ, which has a temperature of 0 minutes or less and a density of θ, 117− or less
The 0 attack division and melt index are less than iogyio, and the growth is! 70g or less of linear low-density summer polyethylene with a molecular weight of 0.002 or higher (not including 0) and a plasticizer of 0.7 to -
0.02 parts by weight of a polyethylene resin composition for a stretchable film.

The present invention will be explained in more detail below.

The present invention is a polyethylene resin composition for a stretchable film, which is made by blending a specific amount of linear low-density polyethylene and a plasticizer with a co-fL@body of ethylene and an α-olefin having 3 or more carbon atoms having specific physical properties. .

Ethylene and α having 3 or more carbon atoms used in the present invention
- A copolymer with olefin (hereinafter simply referred to as ethylene copolymer) has a melt index of 2Ji.
/10 minutes or less, preferably 0. /-27//10 minutes, more preferably 0.2 to /ji/10 minutes, and the density is θ, 1i7cvt or less, preferably O
Jj~O0/11/cr/l, more preferably HaOJJ~0.90II/crA, and the fluidity ratio is preferably 30 or less! ~2, more preferably 10~! It is in the range of If the above melt index is higher than the upper limit, the film becomes brittle (
,? If the density is too high and the density is higher than the upper limit, it will become soft (wrinkle), the film will have insufficient extensibility, and the flow ratio will be 3.
If it is higher than 0, the physical properties of the film will deteriorate, which is not preferable. The above ethylene copolymer has an elongation of 100θ% or more,
Desirably, 200% or more is preferably used.

In the method of the present invention, the melt index is JIS
It is a value measured at 0℃ in accordance with K d2 01C, elongation is a value measured in accordance with the method for measuring elongation at cutting in the tensile test section of JIS K 430/, and density is It is a value measured in accordance with JIS K, <7≦OVc, and the flow ratio is a value measured using the above-mentioned melt index measuring device, with a shear force of 101' dynes/d (load ///3y) and 108 dynes/cII ( Load///, 7/JF) to extrusion i2 (11//o min).

α-olefin copolymerized with ethylene Teha, 7'
robirene, phten-/, pentene-7゜hexene-/,
Coumethylpentene/etc. Among these, propylene and butene are preferable.The ethylene copolymer used in the present invention is a ternary copolymer made by copolymerizing ethylene, an α-olefin having 3 or more carbon atoms, and a non-conjugated diene. Also includes merging. Examples of such non-conjugated dienes include /, 4t, dicyclopentadiene, ethylidene norbornene, and the like.

Ethylene copolymers are produced using a Ziegler-Natsuta catalyst, in particular a catalyst consisting of a vanadium compound such as vanadium trichloride or vanadium tetrachloride and an organoaluminium compound, to produce ethylene and an α-olefin, and in some cases a non-conjugated diene. It can be produced by copolymerizing with.

・In addition, what is the ethylene content of the ethylene copolymer used in the present invention? It is desirable that the α-olefin content be in the range of lθ to 60 mol S.

Next, the linear low-density polyethylene used by blending with the above-mentioned ethylene copolymer is a copolymer of ethylene and other α-olefins, and the low-density polyethylene resin produced by the conventional high-pressure method is different. The linear low-density polyethylene may be made of, for example, ethylene and other α-olefins such as butene, hexene, octene, decene, damethylpentene-1, etc. in an amount of about 4t-%-77% by weight, preferably J
-/j Weight: 9% A copolymerized product using a Ziegler type catalyst or a Phillips type catalyst used in the production of high density polyethylene using a medium to low method. By making use of this short chain branching, the density is appropriately reduced to 0. ri/~θ, rijI/c! It is a polyethylene with a structure that is more linear than conventional low-density polyethylene and more branched than high-density polyethylene.

The linear low density polyethylene used in the present invention is
The melt index is 10Ji/10 minutes or less, preferably in the range of Oo- to rg7io minutes, and the elongation is 30
0% or more, preferably 100% or more. If the melt index is larger than 10Ji/10 minutes, it is extremely difficult to form the film, and if the elongation is smaller than θθ, the extensibility of the film will be insufficient, which is not preferable.

Furthermore, the density of the linear low density polyethylene is 0.9Jj
l/cd or less, extra busy 0. ? 10-,0,9jθ1/cd
From the point of view of film softness, it is desirable that the fluidity ratio be in the range of 10 to 1, especially /! ~3! From the viewpoint of film strength and transparency, the range is preferably .

The resin composition of the present invention is made by blending the above-mentioned ethylene copolymer with a specific amount of linear low-density polyethylene and a plasticizer.

Plasticizers that are usually used as plasticizers for vinyl chloride resins can be used, and are not particularly limited, such as phthalate ester plasticizers, aromatic carboxylic ester plasticizers, fat Group dibasic acid ester plasticizers, aliphatic ester derivative plasticizers, phosphate ester plasticizers, epoxy plasticizers, chlorine plasticizers, polyester plasticizers, and other plasticizers are used.

Examples of phthalate ester plasticizers include dimethyl phthalate, diethyl phthalate, di-coethyl phthalate, di-inoctyl phthalate, dinonyl phthalate, diinnonyl phthalate, didecyl heptathalate, diindecyl heptathalate,
Diethyl phthalate, dichlorosil phthalate, diphenyl phthalate, dibenzyl phthalate, di(mixed alcohol) phthalate, diethyl phthalate, butyl lauryl phthalate, butyl benzyl phthalate, butyl octyl phthalate, octyl decyl phthalate, butyl cyclohexyl 7 talates etc.

Examples of aromatic carboxylic acid ester plasticizers include tri-coethylhexyl trimellitate, tri-n-octyl trimellitate, and ethylene glycol dibenzoate.

Examples of aliphatic dibasic acid ester plasticizers include di-n-hechudyl adipate, dioctyl adipate, di-n
-ethylhexyl adipate, diindecyl adipate, dicabryl adipate, dibutyl sebacate, dioctyl sebacate, di-ethylhexyl sebacate,
Dioctyl azelate, di-ethylhexyl azelate, butyl fumarate, dioctyl fumarate 1, dioctyl succinate, diindecyl succinate, dioctyltetrahydroaliphatic ester derivative plasticizers include butyl oleate, methyl acetyl, etc. Examples include ricino L/-to, dipentaerythritol ester, and pentaerythritol ester.

Examples of phosphate ester-based softeners include trioctyl phosphate, trichloroethyl phosphate, tributyl phosphate, tri(,2-ethyl)phosphate, driftoxyethyl phosphate, triphenyl phosphate, cresyl diphenyl phosphate, Examples include tricresyl phosphate, diphenyloctyl phosphate, and the like.

Examples of the epoxy plasticizer include butyl evo-medium distearate, octyl epoxy stearate, octyl epoxy benzoate, epoxidized soybean oil, benzyl epoxy stearate, and epoxidized dioctyl hexahydrophthalate.

Examples of the chlorinated plasticizer include chlorinated paraffin, chlorinated methyl stearate, chlorinated diphenyl, benzyl laurate salt'X, and chlorinated diphenylbenzene.

Examples of polyester plasticizers include polypropylene adipate and polypropylene sebacate.

These plasticizers can be used alone or in combination of two or more.

In the present invention, the polyethylene resin composition for a stretchable film contains the linear low-density polyethylene in an amount greater than θ and 70 parts by weight or less, preferably 1. < is 10 to 1 parts and the above-mentioned particulate agent o, i to θ! Quantity part.

Okibe or 0. - to 10 parts by weight.

If the blending amount of linear low density polyethylene exceeds the above range, the softness of the film and the adhesion of the film will be insufficient, which is not preferable.

Furthermore, if the content of the plasticizer is less than the lower limit, the film formability will be markedly deteriorated, and the film will suffer from rough skin and protrusion, which is not preferable. On the other hand, if the amount exceeds the upper limit, crosstalk with the ethylene copolymer will be significantly worsened, and the film strength will be significantly lowered, which is not preferable.

The polyethylene resin composition for stretch film of the present invention is
The above-mentioned components are dry-blended using a blender or the like, and then used as is, or after tri-blending, melt-mixed and pelletized using an extruder, etc.
It can be formed into a film using conventional film forming techniques.

Although ordinary film forming methods can be applied to the film forming method, especially in the inflated film forming method, the extrusion temperature /! θ-1 to 0℃, lip gap 0.7~g,
A particularly preferable film can be obtained when molding is performed using a θ-shaped annular die under the conditions of a blow-up ratio of λ to 6, a frost line height of 70 to 1003, and a draft rate of 3 to 7o. Note that the draft rate is a value calculated using the following formula.

In addition, in the T-die film forming method, the extrusion temperature / J
'θ~, 2! Molding is carried out using a die with a lip gap of 0° C., a lip gap of 5 to 6, and a draft ratio of 10 to 0.

Furthermore, the polyethylene resin composition for stretchable films of the present invention may be blended with ≦Xiang-1 antioxidant, ultraviolet absorber, heat stabilizer, antistatic agent, anti-blocking agent, pigment, stabilizer, etc., depending on the purpose of use. can do.

[For production]

In the method of the present invention, a resin composition is prepared by blending a specific amount of linear low-density polyethylene and a plasticizer with a copolymer of ethylene and an α-olefin having 3 or more carbon atoms, which has specific physical properties. By using this, when made into a film, it is possible to provide high elongation and sufficient mechanical strength even beyond the elastic limit.

〔Example〕

Example / Ethylene-propylene copolymer (melt index =
θ, ay/10 min, density = Of t i /d1 elongation = / J 00 :2.077/10
min, elongation = (ooX, flow ratio: /r1 density: θ, r20
1/d1. Copolymerization component Nibutene-7, copolymerization amount: 0% by weight) / 7.7 parts by weight and dioctyl phthalate)
(DOP), after tri-blending 2.7 parts by weight, cylinder diameter! The mixture was melt-kneaded and extruded into pellets at a temperature of 710° C. using a θ■φ single-screw extruder. This was then extruded using an inflation molding machine manufactured by Modern Machinery Co., Ltd. equipped with a Delsa 4tO■φ extruder equipped with an annular slit diameter of 100■φ, an inflation die with a lip clearance of 82mm, and a cooling air ring, and an extrusion temperature of l! θ
℃, extrusion amount/OkQ/hT, blow-up ratio (BU
R) i, o, 70 lines height 32cm.

Pickup speed 4. Inflation molding was performed under conditions of r m 7 minutes to obtain an blown silane film with a thickness of 30 μm. Table 1 shows the results of measuring various properties of the obtained blown silane film. The physical properties in Table 1 were measured using the following measurement method.

(a) The surface condition of the film: Visually determine whether or not so-called shark skin (Shark 5kin) has occurred.

(b) Blocking property of the film In the case of an blown-in blown film, the overlapped films completely fused together and could not be peeled off at all.

Those that can be easily peeled off by hand are good - (C) Coefficient of friction of the film (C, O, F) /60 x 10■ and /6 with the extrusion direction of the film as the longitudinal direction
0x43. Cut out two test pieces j.

A film of /lO×IO is fixed to a board with felt attached to the tiltable surface. (The inclination direction is the longitudinal direction.) /40X4j, jam film has a bottom surface of 1OOX40
．． Fix it so as to cover the bottom surface of the rectangular (sponge attached) weight/IQj weight.

A weight is placed on a film attached to an inclined plate, and the inclined plate is gradually inclined to determine the angle at which the weight begins to slide (tanθ).
Measure.

Repeat the same operation three times and use the average value.

(d) Adhesive diameter 10. Prepare a mold with a hole 2mm deep, and fix it to the top of the mold with a film adhesive.
The inside of the above hole is depressurized at a decompression degree of -2r O'rorr,
Place the film tightly inside the hole.

A case where the film was in contact with the bottom surface of the hole by at least aO- or more and no tearing occurred was considered good, and a case where the contact area was 4to- or less or the film was torn was judged as poor.

(e) Tensile elongation Measured in accordance with JIS Z/7θλ.

Examples 2 to 6 7 The same procedure as in Example 1 was carried out except that the household charge and the mixing ratio were changed as shown in Table 7. The results are shown in Table 7.

Comparative example 1-! The same procedure as in Example 1 was carried out except that the raw materials and blending ratios with physical properties shown in Table 7 were changed.

The results are shown in Table 7.

Comparative Example O As a resin composition, ethylene-vinyl acetate copolymer CM
I=! i/10 minutes, obedience = o, ri! 1/d, vinyl acetate content = 3%) was carried out in the same manner as in Example 1. As a result, the surface condition and blocking degree of the film were good. [Effects of the Invention] The film obtained from the polyethylene resin composition for stretchable films of the present invention has high extensibility, and even if it exceeds its own elastic limit, Since the film has good moldability and mechanical strength, and has good opening properties, when used in the process (1) above, it can be vacuum-adhered to the master mold without heat treatment.

Further, the above-mentioned film can be used in applications where it is desirable to use a stretchable film, such as packaging materials such as stretch packaging, and simple finger bags formed by stretching the fingers, gloves, etc.

[Brief explanation of the drawing]

Figures 1 to 1! The figure is a partially broken pressure surface diagram illustrating the V-process step by step. In the figure, 7 is a matrix, C is a molding surface, 3 is a film, and G is a frame.

Claims (1)

[Claims] (1) 100 parts by weight of a copolymer of ethylene and α-olefin having 3 or more carbon atoms with a melt index of 2 g/10 minutes or less and a density of 0.91/cm^3 or less and a melt index of 10 g/cm^3 or less. A polyethylene resin composition for a stretchable film comprising 70 parts by weight or less (excluding zero) of linear low-density polyethylene that elongates in 10 minutes or less and has an elongation of 500% or more and 0.1 to 20 parts by weight of a plasticizer. .