JPH11115089A - Manufacture of laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a continuous manufacturing method of a laminated film, which has an excellent balance between its seal strength and its easy peelability and excellent sealing properties. SOLUTION: This film is produced by coextruding an ethylene-based resin Y and a resin composition X under the temperature range of melted resin of 140-200 deg.C. Further, the resin composition X includes 5-40 wt.% of styrene-based resin and 60-95 wt.% of olefin-based resin, the solubility parameter SP of which is 8.45-8.70 and no polymer in which includes the repeating unit derived from an aromatic vinyl compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a laminated film.

[0002]

2. Description of the Related Art In packaging materials, it is common to form a laminate in which a heat seal (sealant) layer is formed on a base material. Examples of the sealant material include polyethylene, polypropylene, and ethylene copolymers. Olefin resins are mainly used. The laminate having the sealant layer formed thereon is used as a bag-shaped packaging container, or as a lid material of a cup-shaped or box-shaped packaging container made of plastic, paper, or the like. These packages need to have high sealing strength and excellent sealing properties, and also have excellent easy-opening properties (easy-opening properties) when the contents are used. In the case of a bag-shaped packaging container, the bag may be torn and opened, but in the case of a cup-shaped or box-shaped packaging container lid, the lid is often peeled off from the container body and opened. The material must be easy to peel from the container (easy peeling property).

[0003] As a sealant material having an easy-peeling property, a material composed of an ethylene-based resin composition is mainly used. For example, JP-A-7-207074 and JP-A-8-20774
It is disclosed in, for example, Japanese Patent No. 48849. A sealant film made of an ethylene-based resin composition generally has low rigidity, so that when peeled from a container, the sealant material stretches like a string between a container and a lid, and the appearance of a peeling interface with the container is inferior. There was a problem. Moreover, the sealant material composed of the ethylene-based resin composition often has insufficient sealing strength with respect to the container composed of the styrene-based resin.

On the other hand, a sealant film made of a styrene-based resin composition is excellent in the appearance of the peeling interface and easy-peeling to a container made of a polystyrene-based resin, but has a high sealing start temperature (low-temperature sealing). Inferiority).

Japanese Patent Application Laid-Open No. 9-151284 discloses a styrene resin and a solubility parameter of 8.45.
To 8.70, and a resin film comprising a resin composition containing an olefin-based resin not containing a repeating unit derived from an aromatic vinyl compound in a polymer is disclosed, and the sealing strength is improved. However, in the inflation processing method, there is a problem that the bubble is difficult to stabilize and continuous processing is insufficient.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an easy peel property for a container made of a styrene-based resin, to have an excellent appearance of a peeling interface, to have an excellent balance between seal strength and easy peel property, and to maintain a low temperature. An object of the present invention is to provide a method for continuously manufacturing a laminated film having excellent sealing properties by inflation processing.

[0007]

Means for Solving the Problems As a result of intensive studies, the present inventors have achieved the object of the present invention by co-extrusion of an ethylene resin and a specific resin composition at a specific molten resin temperature and inflation processing. The present invention was completed by conducting various studies.

That is, the present invention relates to a laminated film comprising at least two layers of a layer composed of an ethylene resin (Y) other than the following component (B) and a layer composed of the following resin composition (X); A method for producing a laminated film in which at least one surface layer is a layer composed of a resin composition (X), wherein the ethylene-based resin (Y) and the resin composition (X) are melted at a molten resin temperature of 140 to 200 ° C. This is a method for producing a laminated film, comprising coextrusion and inflation processing in a range. Resin composition (X): A resin composition containing the following component (A) in an amount of 5% by weight or more and less than 40% by weight, and component (B) containing more than 60% by weight and 95% by weight or less. (A) component: styrene resin (B) component: solubility parameter (SP) is 8.45 to
Olefinic resin having a molecular weight of 8.70 and containing no repeating unit derived from an aromatic vinyl compound in the polymer. Hereinafter, the present invention will be described in detail.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The resin composition (X) used in the present invention
Is a resin composition containing 5% by weight or more and less than 40% by weight, preferably 10-30% by weight, of component (A) and more than 60% by weight and less than 95% by weight, preferably 70-90% by weight of component (B). Things. (A) component: styrene resin (B) component: solubility parameter (SP) is 8.45 to
An olefin-based resin that is 8.70 and does not contain a repeating unit derived from an aromatic vinyl compound in the polymer. Here, the mixing ratios of the components (A) and (B) are out of the scope of the present invention. In such a case, the balance between low-temperature sealing, sealing strength, and easy peeling is poor, which is not preferable.

The styrene resin of the component (A) used in the present invention is not particularly limited, and conventional polystyrene, rubber-modified polystyrene and mixtures thereof can be used. Among them, JIS K7 under the condition of a temperature of 200 ° C. and a load of 5 kg
The melt flow rate measured according to 210 is 1 to
Polystyrene or rubber-modified polystyrene having a weight of 20 g / 10 min, preferably 2 to 15 g / 10 min, and more preferably 3 to 10 g / 10 min is preferred.

The component (B) used in the present invention has a solubility parameter (SP) of 8.45 to 8.70 and a repeating unit derived from an aromatic vinyl compound in the polymer (hereinafter referred to as "aromatic compound"). (Referred to as "vinyl compound unit"). Solubility parameter (S
When P) is smaller than 8.45 or larger than 8.70, the balance between the seal strength and the easy peel property is poor.
Here, the solubility parameter (SP) refers to Hildeb
It defines the attractive force between molecules according to the rand-Scatchard theory. A detailed commentary can be found in general textbooks on polymer chemistry, such as "Polymer blends,
Saburo Akiyama et al., CMC Corporation, 4th printing, 125-1
44 (1991) ". The solubility parameter may be determined by an experiment such as a viscosity method or a swelling degree method, or by a calculation from a molecular structure. Used a method proposed by Small to calculate from the molecular structure, which is described in detail in "Journal of Applied Chemistry".
Applied Chemistry), Volume 3, 71-
80, pp are described in detail in (1953) ". Thus, the solubility parameter was calculated using the following equation. SP value _{= ΣF i / V = ρ ·} ΣF i / M where, _{F i} is the molecular The molar attractive force of a constituent group such as an atom or an atomic group, a bond type, etc., V is a molar volume, ρ is a density, M is a molecular weight, and in the case of a polymer, the molecular weight of a repeating unit (that is, a monomer unit) Is shown.
The value of F _i is determined by Smal described in the above two documents.
The value of 1 was used. Copolymers [rho, for .SIGMA.F _i and M, [rho of the homopolymer of the monomer units constituting the copolymer, and calculating the sum of those multiplied by the mole fraction of monomer units in the numerical values of .SIGMA.F _i or M Used.

A resin composition using an olefin resin containing an aromatic vinyl compound unit in a polymer is inferior in the balance between seal strength and easy peelability. Examples of the aromatic vinyl compound include α-alkyl-substituted styrenes such as styrene and α-methylstyrene, and nucleus-substituted alkylstyrenes such as p-methylstyrene.

[0013] The solubility parameter (SP) is 8.45 to
The olefin resin having a molecular weight of 8.70 and containing no aromatic vinyl compound unit in the polymer is selected from unsaturated carboxylic acids, unsaturated carboxylic esters, unsaturated carboxylic anhydrides, and vinyl acetate. Ethylene-based copolymers comprising a repeating unit derived from the above vinyl monomer (hereinafter, referred to as "vinyl monomer unit") and a repeating unit derived from ethylene (hereinafter, referred to as "ethylene unit") are exemplified. . Examples include ethylene-unsaturated carboxylic acid copolymers, ethylene-
Unsaturated carboxylic acid ester copolymer, ethylene-unsaturated carboxylic acid anhydride copolymer, ethylene-vinyl acetate copolymer, ethylene-unsaturated carboxylic acid ester-vinyl acetate terpolymer, two types of ethylene units Multi-component copolymers composed of the above unsaturated carboxylic acid ester units and the like can be mentioned.

Examples of the unsaturated carboxylic acid include acrylic acid and methacrylic acid. Further, as the unsaturated carboxylic acid ester, for example, ethyl acrylate,
Methyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, glycidyl acrylate, methyl methacrylate, ethyl methacrylate,
-Ethylhexyl methacrylate, stearyl methacrylate, glycidyl methacrylate and the like. Examples of the unsaturated carboxylic anhydride include maleic anhydride. Preferred specific examples of the component (B) include ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-methyl methacrylate copolymer. , Ethylene-ethyl methacrylate copolymer, ethylene-vinyl acetate copolymer, ethylene-methyl acrylate-glycidyl methacrylate copolymer, ethylene-methyl methacrylate-
Glycidyl methacrylate copolymer, ethylene-vinyl acetate-glycidyl methacrylate copolymer, ethylene-
And maleic anhydride copolymer.

The content ratio of the vinyl monomer unit and the ethylene unit in the ethylene copolymer can be appropriately determined within a range that gives a copolymer having a solubility parameter (SP) of 8.45 to 8.70. it can. The content of the vinyl monomer unit is preferably 5 to 60% by weight. Further, the bonding mode of the vinyl monomer unit and the ethylene unit in the ethylene-based copolymer, for example, random, block,
The alternation is not limited at all. Among the specific examples of the component (B), an ethylene-methyl methacrylate copolymer and an ethylene-vinyl acetate copolymer are preferable, and the content of the methyl methacrylate unit is 15 to
More preferred is 50% by weight, preferably 20-45% by weight of ethylene-methyl methacrylate copolymer.

The method of mixing the above components (A) and (B) is not particularly limited. For example, a method of thoroughly mixing the respective pellets by dry blending, or a method of melting and kneading the blended pellets with an extruder followed by pelletizing And re-granulation in the form. In order to improve the dispersibility of each component, a method of melt-kneading with an extruder and then re-granulating into pellets is preferable.

The resin composition (X) used in the present invention may contain a compatibilizer, a lubricant, an anti-blocking agent,
An antistatic agent, an antioxidant, a heat stabilizer, an ultraviolet absorber, a pigment, a dye, an antibacterial agent, an antifogging agent and the like may be contained. In particular, when co-extrusion and inflation processing of the ethylene resin (Y) and the resin composition (X), when the inner layer side is a layer composed of the resin composition (X), the resin composition (X) is used.
It is preferable to use an anti-blocking agent added therein. The average particle size of the anti-blocking agent is usually 1.0 to 2
0 μm, preferably 2 to 10 μm. The amount of the anti-blocking agent to be added is 0.05 to 2 parts by weight, preferably 0.1 to 1.5 parts by weight, based on 100 parts by weight of the resin composition (X). Specific examples of the anti-blocking agent include cross-linked polymethyl methacrylate and cross-linked poly (methyl methacrylate-
Organic fine particles such as powders such as styrene), crosslinked silicone, and crosslinked polystyrene; and inorganic fine particles such as silicon dioxide, talc, diatomaceous earth, kaolin, zeolite, and synthetic aluminosilicate powder.

The ethylene resin (Y) used in the present invention is:
An ethylene resin other than the component (B). Examples of the ethylene-based resin (Y) include ethylene-α-olefin copolymers such as polyethylene, ethylene-butene-1 copolymer and ethylene-hexene-1 copolymer, and mixtures thereof. Among them, the temperature 190
The melt flow rate measured according to JIS K7210 under the condition of 2.degree.
g / 10 minutes, polyethylene, ethylene-butene-
Preferred are ethylene-α-olefin copolymers such as 1 copolymer, ethylene-hexene-1 copolymer and the like, and mixtures thereof. As the α-olefin of the ethylene-α-olefin copolymer, for example, butene-1, hexene-1,
4-methylpentene-1, heptene-1, octene-
Α-olefins having 4 to 10 carbon atoms, such as 1, decene-1 and the like.

The method for producing a laminated film according to the present invention is characterized in that the ethylene resin (Y) other than the above-mentioned component (B) and the above-mentioned resin composition (X), So that the molten resin temperature 140 ~
The co-extrusion is performed at 200 ° C., preferably at 150 to 190 ° C., and inflation is performed. If the molten resin temperature is lower than 140 ° C., extrusion becomes difficult, and if it exceeds 200 ° C., blocking of the film is inferior, which is not preferable. In the production method of the present invention, a known co-extrusion inflation machine is used.

The thickness of the laminated film obtained by the production method of the present invention is not particularly limited, but is usually 10 to 100 μm.
It is. The thickness of the layer made of the ethylene resin (Y) is usually 5 to 50 μm, and the thickness of the layer made of the resin composition (X) is usually 5 to 50 μm.

The laminated film obtained by the production method of the present invention is a laminated film composed of at least two layers of a layer composed of the ethylene resin (Y) and a layer composed of the resin composition (X). The resin used for the layers other than the above layer is not particularly limited, and examples thereof include an ethylene resin or a resin composition containing 50% by weight or more of the ethylene resin.

The laminated film obtained by the production method of the present invention can be used as a lid. As a method of obtaining the lid material, for example, a method of laminating a base material composed of plastic, aluminum foil, paper, and the like and the above-described laminated film, and then processing the laminated body into a predetermined shape may be mentioned. . Here, when laminating, it is necessary to laminate the layer on the opposite side of the layer composed of the resin composition (X) and the substrate. In the case of laminating, at least one surface layer of the laminated film and the substrate of the present invention,
It is preferable to apply a surface treatment such as a corona treatment and laminate the treated surfaces together.

As a method of obtaining a container sealed with a lid, for example, a method of filling the container body with the contents and then heat-sealing the lid to the container body may be mentioned.

[0024]

As described in detail above, according to the present invention,
It is possible to provide a method for efficiently producing a laminated film which is excellent in continuous processability of a film, easy peeling property and blocking property. The laminated film obtained in the present invention is most suitable as a sealant film.

[0025]

Hereinafter, the present invention will be described based on examples.
The present invention is not limited to these examples. In addition, among the evaluation items, the items other than the items described above were implemented as follows.

(1) Film processability A film that could be processed continuously for 10 m was rated as ○, and a film that could not be processed was rated as ×. (2) Easy Peeling An adhesive tape ("Cellophane Tape" manufactured by Nichiban Co., Ltd.) is attached to the layer of the obtained laminated film opposite to the sealant film side, and the sealant film side of the laminated film is adhered to the adherend. Close contact, pressure 3kg / cm ² , time 1 second,
Heat sealing was performed under the conditions of a width of 10 mm and the temperature shown in Table 1. As the adherend, a 0.6 mm thick sheet made of rubber-modified polystyrene (Sumibrite E580, manufactured by Sumitomo Chemical Co., Ltd.) using a V65-1000 sheet extruder manufactured by Tanabe Plastic Machinery Co., Ltd. was used. The heat-sealed sample was cut out to a width of 15 mm, and using an automatic strain type tensile tester manufactured by Toyo Seiki Co., Ltd.
The peel strength when peeling 180 degrees at a pulling speed of 300 mm / min was measured. This peel strength is 300 g / 15
If the width is less than mm, the sealability in practical use is inferior and 200 mm
When the width exceeds 0 g / 15 mm, the easy peel property is poor. (3) Film blocking property Both ends of the obtained blown film were cut and peeled into two films. Those that could be peeled off smoothly were rated as ○, and those that were difficult to peel off were rated X.

Example 1 As the component (A) in the resin composition (X), a rubber-modified polystyrene obtained by continuous bulk polymerization (soft component particle content: 20.8% by weight, melt flow rate: 3.2 g) / 10 minutes)
As the component (B), an ethylene-methyl methacrylate copolymer resin (manufactured by Sumitomo Chemical Co., Ltd., trade name: Acrif WM403, content of methyl methacrylate unit: 38)
80% by weight of pellets having an SP value of 8.50), and the following antiblocking agents and lubricants were added in the amounts shown below.
Using a single-screw extruder with a diameter of φ mm, the pellets were pelletized at a temperature of 190 ° C. As the ethylene resin (Y), low-density polyethylene (Sumitomo Chemical Industries, Ltd., trade name: Sumikasen F
200, a density of 0.923 g / cm ³ , and a melt flow rate of 2.0 g / 10 minutes). Using the above-mentioned materials, a three-layer, three-layer co-pressed inflation film forming apparatus (extruder A (inner layer): 40 mmφ, extruder B (intermediate layer): 50 mmφ, extruder C (outer layer) manufactured by Placo Co., Ltd .: 40m
mφ), and the above resin composition (X) is extruded with an extruder A.
The resin was extruded at a resin temperature of 170 ° C. and an extrusion rate of 5.9 kg / hour, and the ethylene resin (Y) was extruded with extruders B and C at a resin temperature of 170 ° C. and an extrusion rate of 8.2 kg / hour and 9.1 kg / hour. Extrusion under the condition of time, take-off speed12.
Under the condition of 7 m / min, the thickness is 40 μm (resin composition (X)
Was processed into a two-layer laminated film having a thickness of 10 μm), and a corona treatment was performed on the layer side of the ethylene-based resin (Y) so as to have a wetting tension of 45 dyne / cm. Table 1 shows the results. Master batch formulation used Antiblocking agent Synthetic aluminosilicate powder having an average particle diameter of 5.0 μm was prepared by mixing ethylene-hexene-1 copolymer (melt flow rate: 0.8 g / 10 min, density: 0.925 g / c).
5% by weight of a master batch kneaded at a concentration of 10% by weight into the m ³ ) (0.1% as an anti-blocking agent).
5 parts by weight). Lubricant The powder of erucamide was mixed with an ethylene-hexene-1 copolymer (melt flow rate: 0.8 g / 10 min, density:
1.5 parts by weight of a master batch kneaded at a concentration of 4% by weight to 0.925 g / cm ³ ) was added (0.06 part by weight as a lubricant).

Comparative Example 1 A single-layer film made of the resin composition (X) was prepared by using the same resin composition (X) as in Example 1 and using the same co-pressed inflation film forming apparatus and processing conditions as in Example 1. However, it was difficult to start the bubble and it was not possible to process it.

Comparative Example 2 Example 1 was repeated except that the resin composition (X) and the low-density polyethylene (Y) were melted at a temperature of 210 ° C. Table 1 shows the results.

Comparative Example 3 As the resin composition (X), the same components (A) and (B) as in Example 1 were used, and an ethylene-hexene-1 copolymer obtained by a high-pressure ion polymerization method. (Melt flow rate: 0.8 g / 10 min, density: 0.925 g /
cm ³ ) pellets of 10% by weight and 40% by weight, respectively.
The procedure was performed in the same manner as in Comparative Example 1, except that the components were blended at 50% by weight and 50% by weight. Table 1 shows the results.

[0031]

[Table 1]---------------------------------------------------------------------------------------------Example −−−−−−−−−−−−−−−−−− Workability ○ × ○ ○ Easy peeling Peel strength g / 15mm width Heat seal temperature 100 ℃ g / 15mm width 630 − 700 0 120 ℃ g / 15mm Width 990-1000 300 140 ° C g / 15mm Width 970-1100 500 Blocking property-------------------------------

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI // B29K 23:00 25:00 B29L 9:00

Claims (7)

[Claims] 1. A laminated film comprising at least two layers of a layer composed of an ethylene-based resin (Y) other than the following component (B) and a layer composed of the following resin composition (X),
A method for producing a laminated film in which at least one surface layer is a layer composed of a resin composition (X), wherein the ethylene-based resin (Y) and the resin composition (X) are melted at a resin temperature of 140 to 200 ° C. A method for producing a laminated film, comprising co-extrusion and inflation in the range of Resin composition (X): A resin composition containing the following component (A) in an amount of 5% by weight or more and less than 40% by weight, and component (B) containing more than 60% by weight and 95% by weight or less. (A) component: styrene resin (B) component: solubility parameter (SP) is 8.45 to
Olefinic resin which is 8.70 and does not contain a repeating unit derived from an aromatic vinyl compound in the polymer (2) The component (B) comprises ethylene and a repeating unit derived from one or more vinyl monomers selected from unsaturated carboxylic acids, unsaturated carboxylic esters, unsaturated carboxylic anhydrides and vinyl acetate. 2. An ethylene copolymer comprising a derived repeating unit.
A method for producing the laminated film as described above. 3. The method according to claim 2, wherein the component (B) is an ethylene-unsaturated carboxylic acid ester copolymer. 4. The method according to claim 2, wherein the component (B) is an ethylene-methyl methacrylate copolymer or an ethylene-vinyl acetate copolymer. 5. The method according to claim 4, wherein the component (B) is an ethylene-methyl methacrylate copolymer having a content of a repeating unit derived from methyl methacrylate of 15 to 50% by weight. 6. An ethylene resin (Y) comprising polyethylene,
The method for producing a laminated film according to claim 1, which is an ethylene-α-olefin copolymer or a mixture thereof. 7. An anti-blocking agent having an average particle diameter of 1.0 to 20 μm is further added to 100 parts by weight of the resin composition (X).
The method for producing a laminated film according to claim 1, comprising 5 to 2 parts by weight.