JP2003321560A - Method for producing thermoplastic resin film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a thermoplastic film excellent in close adhesion between a film substrate with a coated film and having printing adaptability and anti-static property. <P>SOLUTION: This method for producing the thermoplastic resin film is characterized by oxidation-treating the surface of a thermoplastic resin film (i) containing an unsaturated carboxylic acid-modified polyolefinic resin, applying a surface-modifying agent and then stretching. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a thermoplastic resin film which is useful as a printing paper, a poster paper, a paper such as a sticker or a decorative article. More specifically, the present invention relates to a method for producing a thermoplastic resin film which has excellent adhesion between a coating film and a film base material, and further has printability and antistatic properties.

[0002]

2. Description of the Related Art Conventionally, as a sticker for outdoor advertisement or a label attached to a container for frozen foods, the water resistance of the coated paper which is the sticker or label paper is poor. The coated paper whose surface was coated with a plastic film was used. In recent years, as a promising label material to substitute for a plastic film-coated paper, a thermoplastic resin film having good water resistance, in particular, a polyolefin-based synthetic paper has attracted attention (see Patent Documents 1 to 5).

However, these polyolefin-based synthetic papers are not necessarily satisfactory in printability and processability because the raw material polyolefin is non-polar, and therefore, they are used after being subjected to an appropriate surface treatment. It is normal to do. For example, during the production of a polyolefin synthetic paper, the film surface before stretching is subjected to a corona discharge treatment oxidation treatment, the surface is further coated with a coating liquid, and then stretched, and optionally a surface is subjected to an oxidation treatment such as a corona discharge treatment. The method is known.

[0004] Patent Document 6 discloses that a longitudinally stretched film has three
A corona treatment of 0 to 100 w · min / m ² was performed, the treated surface was coated with an ethylene-vinyl alcohol copolymer coating solution having an ethylene content of 20 to 45 mol%, and after drying, stretched in a transverse direction with a tenter, 30 ~ 100w / min /
Disclosed is a method for producing a laminated resin film, which comprises performing m ² corona treatment. However, the laminated resin film produced by this method has low adhesion between the base material and the coating film, and also has safety and hygiene problems because the coating liquid is an organic solvent. It was rare.

Patent Document 7 discloses a surface treatment method for a thermoplastic resin film, which comprises subjecting a thermoplastic resin film to an oxidation treatment, applying a coating solution of polyethyleneimine, and then stretching. There is. According to this method, the problem of safety and hygiene can be solved because the coating liquid is an aqueous solution, but there is a problem that the printability is low, probably due to the low adhesion between the film substrate and the coating film. Therefore, improvement was needed.

[0006]

[Patent Document 1] Japanese Patent Publication No. 46-40794

[Patent Document 2] Japanese Patent Publication No. Sho 49-1782

[Patent Document 3] JP-A-56-118437

[Patent Document 4] JP-A-57-12642

[Patent Document 5] JP-A-57-56224

[Patent Document 6] JP-A-7-266417

[Patent Document 7] Japanese Patent Laid-Open No. 11-342534

[0007]

DISCLOSURE OF THE INVENTION It is an object of the present invention to provide a method for producing a thermoplastic resin film having excellent adhesion between a film base material and a coating film, and having printability and antistatic property. And

[0008]

In the present invention, the surface of a thermoplastic resin film (i) containing an unsaturated carboxylic acid-modified polyolefin resin is subjected to an oxidation treatment, a surface modifier is applied, and then stretched. A method for producing a thermoplastic resin film is provided.

In the present invention, the thermoplastic resin film (i)
A multilayer having a base layer (ii) made of a thermoplastic resin and a surface layer (iii) made of a thermoplastic resin containing the unsaturated carboxylic acid-modified polyolefin resin on at least one surface of the base layer (ii). It is preferably a resin film. Further, the thermoplastic resin film (i) comprises a base material layer (ii) made of a longitudinally stretched thermoplastic resin, and a heat containing the unsaturated carboxylic acid-modified polyolefin resin on at least one surface of the base material layer (ii). It is preferably a multilayer resin film having a surface layer (iii) made of a plastic resin.

The unsaturated carboxylic acid of the unsaturated carboxylic acid-modified polyolefin resin used in the present invention is acrylic acid,
One or a mixture of two or more selected from methacrylic acid, maleic acid, fumaric acid, itaconic acid, maleic anhydride and itaconic anhydride is preferable, and maleic acid or maleic anhydride is more preferable. preferable. The polyolefin resin of the unsaturated carboxylic acid-modified polyolefin resin used in the present invention is one or a mixture of two or more selected from polyethylene, polypropylene, polybutene-1, ethylene-vinyl acetate copolymer and ethylene-propylene copolymer. Is preferred,
Among them, polypropylene is particularly preferable.

The unsaturated carboxylic acid modified amount of the unsaturated carboxylic acid modified polyolefin resin used in the present invention is 0.01.
It is preferably from 10 to 10% by weight. When the thermoplastic resin film (i) is a single layer, the acid content represented by the following formula is preferably 0.01 to 1.0% by weight.

## EQU3 ## Acid content (% by weight) = M × S ÷ 100 M: Content of unsaturated carboxylic acid-modified polyolefin in thermoplastic resin film (i) (% by weight) S: Amount of unsaturated carboxylic acid modification (weight) %)

When the thermoplastic resin film (i) is a multi-layer, the surface layer (iii) has an acid content of 0.
It is preferably from 01 to 1.0% by weight.

## EQU00004 ## Acid content (wt%) = H × S ÷ 100 H: Content of unsaturated carboxylic acid-modified polyolefin resin in surface layer (iii) (wt%) S: Amount of unsaturated carboxylic acid modification (wt) %)

Further, in the present invention, it is preferable that the thermoplastic resin film (i) contains an inorganic fine powder and / or an organic filler. Furthermore, it is preferable that the thermoplastic resin film (i) is a polyolefin resin, especially a propylene resin. The oxidation treatment in the present invention is
It is preferably at least one kind of treatment selected from corona discharge treatment, flame treatment, plasma treatment, glow discharge treatment and ozone treatment.

The surface modifier used in the present invention is one or more selected from polyethyleneimine-based polymers, polyurethane-based polymers, polyacrylic acid ester-based copolymers and polyester-based copolymers. It is preferable to contain a polymer binder, and it is preferable to further contain an antistatic polymer.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION In the following, after the surface of a thermoplastic resin film (i) containing an unsaturated carboxylic acid-modified polyolefin resin is subjected to an oxidation treatment, a surface treatment agent is applied and then stretching is performed. The method will be described in detail. In addition, in this specification, "-" means the range which includes the numerical value described before and after that as a minimum value and a maximum value, respectively.

[Unsaturated Carboxylic Acid Modified Polyolefin Resin] In the present invention, the unsaturated carboxylic acid modified polyolefin resin is contained in the surface layer of the thermoplastic resin substrate to improve the adhesion between the film substrate and the coating film. I am letting you.
The unsaturated carboxylic acid-modified polyolefin resin used in the present invention is preferably produced by graft-copolymerizing an unsaturated carboxylic acid with a polyolefin resin.

To graft-copolymerize an unsaturated carboxylic acid with a polyolefin resin, the polyolefin resin is dissolved or suspended in an organic solvent, and then an unsaturated carboxylic acid is added to decompose the radical generator. It is possible to use a method in which the temperature is raised to a temperature (generally 50 to 150 ° C.) and a radical generator is added little by little to carry out a graft reaction. Alternatively, it is also possible to use a method in which an unsaturated carboxylic acid, which is a graft monomer, is applied to a polyolefin resin together with a radical generator by heating at 150 to 260 ° C. in an extruder for graft polymerization.

In the present specification, the term "unsaturated carboxylic acid" is used as a concept including not only an unsaturated compound having a --COOH group but also its derivative ester or anhydride. As the unsaturated carboxylic acid, for example,
Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid; unsaturated carboxylic acid esters such as methyl methacrylate, methyl acrylate, butyl fumarate; maleic anhydride, itaconic anhydride, etc. Acid anhydrides and the like. Of these, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, maleic anhydride, and itaconic anhydride are preferable, and maleic acid and maleic anhydride are particularly preferable.

Examples of the olefin resin include polyethylene, polypropylene, polybutene-1, poly-4-methylpentene-1, ethylene-propylene copolymer, ethylene-butene-1 copolymer, ethylene-hexene-1.
Copolymer, ethylene-4 methylpentene-1 copolymer,
Ethylene-octene-1 copolymer, propylene-butene-1 copolymer, propylene-hexene-1 copolymer, propylene-4 methylpentene-1 copolymer, propylene-ethylene-octene-1 copolymer, ethylene -Butadiene copolymer, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, ethylene methyl acrylate copolymer, ethylene acrylic acid copolymer, ethylene methacrylic acid copolymer and the like can be mentioned. Among them, polyethylene, polypropylene, polybutene-1, ethylene-vinyl acetate copolymer and ethylene-propylene copolymer are preferable, and polypropylene is particularly preferable.

The unsaturated carboxylic acid-modified polyolefin resin thus obtained is preferably grafted with an unsaturated carboxylic acid unit in an amount of 0.01 to 10% by weight. If the unsaturated carboxylic acid unit is less than 0.01% by weight, the effect of adding the unsaturated carboxylic acid-modified polyolefin tends to be insufficient, and if it exceeds 10% by weight, the main chain molecular weight is reduced due to the graft polymerization, resulting in a film. The workability during molding tends to deteriorate.

[Thermoplastic Resin Film (i)] The thermoplastic resin used in the thermoplastic resin film (i) is an ethylene resin such as high density polyethylene or medium density polyethylene, or a polyolefin resin such as propylene resin. Resin, polymethyl-1-pentene, ethylene-cyclic olefin copolymer, nylon-6, nylon-6
6, polyamide resins such as nylon-6,10, nylon-6,12, polyethylene terephthalate and its copolymers, thermoplastic polyester resins such as polyethylene naphthalate and aliphatic polyester, polycarbonate,
Examples of the thermoplastic resin include atactic polystyrene, syndiotactic polystyrene, and polyphenylene sulfide. These may be used as a mixture of two or more. Among these thermoplastic resins, it is preferable to use a non-polar polyolefin resin in order to further exert the effects of the present invention. Further, among the polyolefin resins, the propylene resin is preferable from the viewpoint of chemical resistance and cost.

Examples of the propylene-based resin include propylene homopolymers, which are isotactic or syndiotactic and propylene homopolymers having various degrees of stereoregularity, and whose main component is propylene and ethylene and butene. -1, hexene-1, heptene-
A copolymer with an α-olefin such as 1,4-methylpentene-1 is used. This copolymer may be a binary system, a ternary system or a quaternary system, and may be a random copolymer or a block copolymer. When a propylene homopolymer is used, it is preferable to add 2 to 25% by weight of a resin having a melting point lower than that of a propylene homopolymer such as polyethylene or ethylene / vinyl acetate copolymer in order to improve the stretchability. .

Whether the thermoplastic resin film (i) is a single layer or a two-layer structure of a base material layer (ii) and a surface layer (iii), the front and back surfaces of the base material layer (ii) are Surface layer (ii
It may have a three-layer structure in which i) exists or a multi-layer structure in which another resin film layer exists between the base material layer (ii) and the surface layer (iii). When the plastic resin film (i) is a single layer, the acid content represented by the following formula is 0.01 to 1.
It is preferably 0% by weight.

## EQU00005 ## Acid content (wt%) = M × S ÷ 100 M: Content of unsaturated carboxylic acid-modified polyolefin resin in thermoplastic resin film (i) (wt%) S: Modification amount of unsaturated carboxylic acid (weight%)

When the thermoplastic resin film (i) is a multilayer, the acid content represented by the following formula is 0.01 to 1.0% by weight.
Is preferred.

## EQU00006 ## Acid content (wt%) = H × S ÷ 100 H: Content of unsaturated carboxylic acid-modified polyolefin resin in surface layer (iii) (wt%) S: Amount of unsaturated carboxylic acid modification (wt) %) Acid content is 0.
If it is less than 01% by weight, the adhesion between the base material and the coating film tends not to be improved, and if it exceeds 1.0% by weight, not only the effect is saturated, but also the film becomes yellow and the surface becomes sticky. There is a tendency that adverse effects such as

The thermoplastic resin film (i) may or may not contain the inorganic fine powder or the organic filler. When the thermoplastic resin film (i) is a polyolefin-based resin film and (i) is a single layer and contains an inorganic fine powder, the polyolefin-based resin and the unsaturated carboxylic acid-modified polyolefin-based resin are usually 40 to It is preferable to contain 99.5% by weight and 60 to 0.5% by weight of the inorganic fine powder.

When the thermoplastic resin film (i) has a multi-layer structure and the base material layer (ii) and the surface layer (iii) contain inorganic fine powder, the base material layer (ii) usually contains a polyolefin resin. 40-99.5% by weight, inorganic fine powder 60-0.5% by weight, surface layer (iii) 25-100% by weight of polyolefin resin and unsaturated carboxylic acid modified polyolefin resin, inorganic fine powder 75 to
It is preferable to contain 0% by weight. The inorganic fine powder contained in the base material layer (ii) having a single-layer structure or a multi-layer structure is 60
When the content exceeds the weight%, the stretched resin film tends to be easily broken during the transverse stretching performed after the longitudinal stretching. Surface layer (ii
If the inorganic fine powder contained in i) exceeds 75% by weight, the surface strength of the surface layer after transverse stretching is low and paper peeling tends to occur.

As the inorganic fine powder, calcium carbonate,
Examples include calcined clay, silica, diatomaceous earth, talc, titanium oxide, barium sulfate, and alumina. In the present invention, it is preferable to use one having an average particle diameter of 0.01 to 15 μm, and more preferably to use one having an average particle diameter of 0.2 to 7 μm. If the average particle size is less than 0.01 μm, problems such as classification and aggregation tend to occur during mixing with the thermoplastic resin, and if it exceeds 15 μm, abnormal appearance such as lumps tends to occur.

When the thermoplastic resin film is a polyolefin resin film, the organic filler is
Polyethylene terephthalate, polybutylene terephthalate, polycarbonate, nylon-6, nylon-
6,6, melting point higher than that of polyolefin resin such as cyclic olefin polymer (for example, 170 to 300 ° C)
Or glass transition temperature (for example, 170 ° C. to 280 ° C.)
C.) is used.

If desired, stabilizers, light stabilizers, dispersants, lubricants and the like may be added. As a stabilizer, 0.001 to 1% by weight of sterically hindered phenols, phosphorus, amines, etc., as a light stabilizer, 0.001 to 1% by weight of sterically hindered amines, benzotriazoles, benzophenones, etc. A fine powder dispersant, for example, a silane coupling agent, a higher fatty acid such as oleic acid or stearic acid, a metal soap, polyacrylic acid, polymethacrylic acid, or a salt thereof may be added in an amount of 0.01 to 4% by weight. Good.

[Molding of Resin Film] The molding method of the thermoplastic resin film (i) is not particularly limited, and various conventionally known methods can be used. Specific examples include a single layer connected to a screw type extruder. Alternatively, cast molding for extruding a molten resin into a sheet using a multi-layer T die or I die, calender molding, roll molding, inflation molding, cast molding of a mixture of a thermoplastic resin and an organic solvent or oil, or a solvent after calender molding. And removal of oil, molding from a solution of a thermoplastic resin and removal of a solvent. In the case of stretching, various known methods can be used, and specific examples thereof include longitudinal stretching utilizing the peripheral speed difference between roll groups and transverse stretching using a tenter oven.

[Resin Film] The thermoplastic resin film (i) may be stretched using a thermoplastic resin,
Although it may not be stretched, it is necessary that it can be stretched after the surface treatment. Also,
It may contain no inorganic fine powder or organic filler, or may contain it. In addition, a resin layer which is not stretched may be provided on at least one surface of the stretched base layer.

When the thermoplastic resin film (i) is a polyolefin resin film and is a single layer and contains an inorganic fine powder, preferably 40 to 99.5% by weight of the polyolefin resin and the inorganic fine powder are used. Powder 60-0.5
% By weight, unsaturated carboxylic acid-modified polyolefin resin 1
By stretching a resin film comprising a resin composition containing 50% by weight to a temperature lower than the melting point of the polyolefin resin as the above component, preferably 3 to 60 ° C. lower in a uniaxial direction or a biaxial direction, a film is obtained. A microporous stretched resin film having fine cracks on the surface and fine pores (voids) inside the film can be obtained.

In another preferred embodiment, the thermoplastic resin film (i) has a multilayer structure and has a base material layer (i).
A resin film composed of a resin composition containing 40 to 100% by weight of the polyolefin resin of i) and 60 to 0% by weight of the inorganic fine powder is formed at a temperature lower than the melting point of the polyolefin resin of the base material layer (ii), preferably Stretched in the machine direction at a temperature lower by 3 to 60 ° C., and then the surface layer (iii) contains 25 to 99% by weight of polyolefin resin and 75 to 75% of inorganic fine powder.
Surface treatment by laminating a surface layer (iii) on at least one side of the base layer (ii) with a resin film comprising a resin composition containing 0% by weight and 1 to 80% by weight of an unsaturated carboxylic acid-modified polyolefin resin. Can be used for

The thickness of the resin film used for the surface treatment of the first stage used in the present invention can be appropriately selected depending on the stretching ratio and the thickness of the film required after stretching.
Generally from 20 to 4000 μm, preferably from 100 to 300
Those having a range of 0 μm are used.

[Surface Oxidation Treatment] Examples of the surface oxidation treatment of the above-mentioned base material include at least one treatment method selected from corona discharge treatment, flame treatment, plasma treatment, glow discharge treatment and ozone treatment. Corona treatment and frame treatment are preferable. In case of corona treatment, the treatment amount is 600 to 12,000 J / m ² (10 to 200 W
-Min / m < ² >), preferably 1,200-9,000 J /
m ² (20 to 180 W · min / m ² ). 600 J / m
^When it is less than ² (10 W · min / m ² ), the effect of corona discharge treatment is insufficient, and cissing tends to occur during subsequent coating of the surface modifier. Also, 12,000 J / m ² (18
If it exceeds 0 W · min / m ² ), the effect of the treatment will reach the ceiling, so 12,000 J / m ² (180 W · min / m ² ) or less is sufficient. For frame processing, 8,000-200,0
00 J / m ² , preferably 20,000 to 100,000
0 J / m ² is used. Below 8,000 J / m ² ,
The effect of flame treatment is insufficient, and cissing tends to occur during subsequent application of the surface modifier. Also, 20
If it exceeds 10,000 J / m ² , the effect of the treatment will reach the ceiling, so 200,000 J / m ² or less is sufficient.

[Surface modifier] The surface modifier used in the present invention is selected from the following polymer binders and is preferably a single component or a mixture of two or more components.
It is preferable to add an antistatic polymer from the viewpoint of antistatic properties of the film and a crosslinking agent from the viewpoint of improving the adhesion between the substrate and the coating layer.

Polymer binder As the polymer binder, an unsaturated carboxylic acid-modified polyolefin resin and an aqueous resin having high adhesion to the polyolefin resin and having printability are preferable. Examples of the polymer binder include polyethyleneimine, alkyl-modified polyethyleneimine having 1 to 12 carbon atoms,
Polyethyleneimine-based polymers such as poly (ethyleneimine-urea) and ethyleneimine adducts of polyamine polyamides and epichlorohydrin adducts of polyamine polyamides, acrylic acid amide-acrylic acid ester copolymers, acrylic acid amide-acrylic acid ester-methacryl Acid ester copolymer, polyacrylamide derivative,
Acrylic ester-based polymers such as oxazoline group-containing acrylic ester-based polymers, polyvinylpyrrolidone, polyethylene glycol, etc., in addition to polyvinyl acetate, polyurethane, ethylene-vinyl acetate copolymer, polyvinylidene chloride, chlorinated polypropylene, acrylic Nitrile-
A water-soluble resin such as a butadiene copolymer or polyester, or a water-dispersible resin can be used. Of these, polyethyleneimine-based polymers, polyurethane-based polymers, polyacrylic acid ester-based copolymers, and polyester-based polymers are preferable.

Antistatic Polymer As the antistatic polymer, cation type, anion type,
Amphoteric type, nonionic type, etc. can be used. Examples of the cation type include those having an ammonium salt structure or a phosphonium salt structure. As anion type, alkali metal salts such as sulfonic acid, phosphoric acid and carboxylic acid, for example, acrylic acid, methacrylic acid, maleic acid (anhydride)
And the like having an alkali metal salt structure (for example, lithium salt, sodium salt, potassium salt, etc.) structure in the molecular structure.

The amphoteric type contains both the above-mentioned cation type and anion type structures in the same molecule, and examples thereof include betaine type. Examples of the nonionic type include ethylene oxide polymers having an alkylene oxide structure and polymers having an ethylene oxide polymerization component in the molecular chain. In addition, a polymer having boron in its molecular structure can be mentioned as an example.

Of these, nitrogen-containing polymers are preferable, and tertiary nitrogen- or quaternary nitrogen-containing acrylic polymers are more preferable. By adding an antistatic polymer to the above-mentioned polymer binder, it is possible to reduce dust adhesion and troubles due to electrification during printing. The addition amount of the antistatic polymer is usually in the range of 1 to 200 parts by weight with respect to 100 parts by weight of the above polymer binder.

Crosslinking Agent By adding a crosslinking agent to the above polymer binder, the coating strength and water resistance can be further improved. Examples of the cross-linking agent include epoxy-based compounds such as glycidyl ether and glycidyl ester, epoxy resin, isocyanate-based, oxazoline-based, formalin-based, hydrazide-based, and carbodiimide-based water-dispersible resins. The amount of the crosslinking agent added is usually in the range of 1 to 200 parts by weight with respect to 100 parts by weight of the above polymer binder.

Pigment In the ink fixing agent layer of the present invention, raw material components can be added to improve the fixability of the ink components. The pigment component is
One kind or two or more kinds selected from the inorganic fine powders and the organic fillers described in the above section of the substrate can be used.

Other Auxiliary Agent The ink fixing agent layer may further contain a surfactant, a defoaming agent, a water-soluble metal salt and other auxiliary agents.

[Formation of Surface Modification Layer] Each of the components of the surface modification layer may be used after being dissolved in water or a hydrophilic solvent such as methyl alcohol, ethyl alcohol or isopropyl alcohol. It is preferably used in the form. The solution concentration is usually 0.05 to 20% by weight, preferably 0.1 to 10% by weight. 0.0
If it is less than 5% by weight, it is necessary to take measures such as a drying process of water and extension of drying time. If it exceeds 20% by weight, coating unevenness tends to occur.

The coating method is performed by a roll coater, a blade coater, a bar coater, an air knife coater, a size press coater, a gravure coater, a reverse coater, a die coater, a lip coater, a spray coater, etc., and a smoothing step is added if necessary. Alternatively, excess water and hydrophilic solvent are removed through a drying process. The coating amount is 0.005 to 10 g as the solid content after drying.
/ M ^2, preferably from 0.01 to 1 g / m ^2, more preferably 0.01~0.6g / m ^2. 0.005 g / m ²
If less than 10, the effect of the polymer binder is insufficient and 10
If it exceeds g / m ² , the difference in substrate thickness between the coated portion and the non-coated portion becomes large, and it tends to be difficult to uniformly stretch the film.

[Stretching] Various conventionally known methods can be used for the stretching. As a specific example, in the case of a non-crystalline resin, the glass transition temperature of the thermoplastic resin to be used or higher, or in the case of a crystalline resin, is used. Can be carried out in a known temperature range suitable for each thermoplastic resin from the glass transition temperature of the amorphous portion to the melting point of the crystalline portion or less, and longitudinal stretching utilizing the peripheral speed difference of the roll group, using a tenter oven Horizontal stretching, rolling, simultaneous biaxial stretching using a combination of a tenter oven and a linear motor, and the like.

The stretch ratio is not particularly limited and is appropriately selected depending on the purpose and the characteristics of the thermoplastic resin used. For example, when a propylene homopolymer or a copolymer thereof is used as the thermoplastic resin, it is about 1.2 to 12 times, preferably 2 to 10 times, when it is stretched in one direction.
In the case of biaxial stretching, the area magnification is 1.5 to 60 times, preferably 10 to 50 times. When using other thermoplastic resins, it is 1.2 to 10 times, preferably 2 to 5 times in the case of stretching in one direction, and 1.5 to 20 times in area magnification in the case of biaxial stretching, preferably Is 4 to 12 times. Further, heat treatment at a high temperature is performed if necessary.

The stretching temperature is 2 to 60 ° C. lower than the melting point of the thermoplastic resin used, and 110 to 164 when the resin is a propylene homopolymer (melting point 155 to 167 ° C.).
C., 110 to 120.degree. C. for high-density polyethylene (melting point 121 to 134.degree. C.) and 104 to 115.degree. C. for polyethylene terephthalate (melting point 246 to 252.degree. C.), which are appropriately selected depending on the stretching process and conditions. The stretching speed is 20 to 350 m / min.

When the thermoplastic resin film contains inorganic fine powder or organic filler, fine cracks are formed on the film surface and fine voids are formed inside the film. The thickness of the stretched thermoplastic resin film is 20 to 500 μ.
It is preferably m, and more preferably 35 to 300 μm.

(Physical Properties of Stretched Film) The stretched thermoplastic resin film has a porosity of the base material portion represented by the following formula of 10 to 60% and a density of 0.650 to 1.20 g / c.
m ³ , opacity of 75% or more, Bekk smoothness of 50 to 2
It has a physical property of 5,000 seconds.

[Equation 7]

The thermoplastic resin film obtained in the present invention has good adhesion between the film base material and the coating film and also has excellent printability, and can be used for letterpress printing, gravure printing,
It can be used not only in flexographic printing and solvent-based offset printing but also in UV-curable offset printing.

[0052]

EXAMPLES The features of the present invention will be described more specifically below with reference to production examples, examples, comparative examples, and test examples. Materials, usage amounts, ratios, processing contents, processing procedures, and the like shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be limitedly interpreted by the following specific examples. In addition, "part" in a component mixture ratio shows a "weight part."

<Production Example> Preparation of Surface Modifying Agents Surface modifying agents G1 to G7 used in Examples and Comparative Examples are as described below. (G1) Polymer binder component 1: Modified ethyleneimine-based polymer In a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet, polyethyleneimine "Epomin" was added.
P-1000 (polymerization degree 1600) "(manufactured by Nippon Shokubai Co., Ltd., trade name), 100 parts of a 25 wt% aqueous solution, 10 parts of glycidol and 10 parts of propylene glycol monomethyl ether were added, and the mixture was stirred under a nitrogen stream to give 80. 1 at a temperature of ℃
A glycidol-modified polyethyleneimine aqueous solution was obtained by performing a modification reaction for 6 hours. After drying this, infrared spectroscopy, ¹ H-nuclear magnetic resonance spectroscopy ( ¹ H-NMR), and
¹³ C-nuclear magnetic resonance spectroscopy ( ¹³ C-NMR) shows a structure formed by the addition of the epoxy group of glycidol to the nitrogen of polyethyleneimine, and 23% of the nitrogen of polyethyleneimine is the product reacted with glycidol. It was confirmed.

(G2) Polymer binder component 2: polyacrylic ester copolymer Polyacrylic ester resin emulsion "DI
CNAL WF-73H "(manufactured by Dainippon Ink and Chemicals, Inc., trade name, solid content concentration 40% by weight) was used.

(G3) Polymer binder component 3: polyurethane-based polymer polyether-based polyurethane resin emulsion "VONDIC 1040NS" (trade name, solid content concentration 50% by weight, manufactured by Dainippon Ink and Chemicals, Inc.) It was used.

(G4) Polymer binder component 4: polyacrylic acid ester copolymer Polyacrylic acid ester resin emulsion "Movinyl 735" (trade name, solid content concentration 40% by weight, manufactured by Clariant Polymer Co., Ltd.) It was used.

(G5) Antistatic Polymer 1: Acrylic ester type antistatic polymer 35 parts of dimethylaminoethyl methacrylate were placed in a four-necked flask equipped with a reflux condenser, a thermometer, a glass tube for nitrogen substitution, and a stirrer. , Ethyl methacrylate 2
0 part, cyclohexyl methacrylate 20 parts, stearyl methacrylate 25 parts, ethyl alcohol 150
And 1 part of azobisisobutyronitrile were added, and a polymerization reaction was carried out at a temperature of 80 ° C. for 6 hours under a nitrogen stream. Then, 70 parts of a 60% solution of 3-chloro-2-hydroxypropylammonium chloride was added, and the mixture was further reacted at a temperature of 80 ° C. for 15 hours, and then ethyl alcohol was distilled off while adding water dropwise to give a final solid content. 30% of a quaternary ammonium salt type copolymer (abbreviation G5) was obtained. This is an alkyl acrylate polymer containing a group represented by the following general formula in the molecular chain.

[0058]

[Chemical 1]

(G6) Crosslinking Agent Component 1: Polyamine Polyamide Derivative Polyamine polyamide epichlorohydrin adduct "W
S-570 (solid content 12.5%) "(Japan PMC Corporation)
(Trade name, manufactured by the company) was used.

(G7) Pigment Component 1: Calcium Carbonate "Brilliant S-15" which is light calcium carbonate
(Trade name, manufactured by Shiraishi Industry Co., Ltd.) was used.

Example 1 (1) Resin Sheet Melt Flow Rate (MFR) 0.8 g / 10 min Propylene Homopolymer [Nippon Polychem Co., Novatec P]
P: EA8], calcium carbonate having an average particle size of 1.5 μm [Bihoku Koka Kogyo Co., Ltd., Softon 1800] 15% by weight of the composition (c ′) was blended into the extruder at 240 ° C. After kneading, the mixture was extruded into a sheet and cooled by a cooling device to obtain an unstretched sheet. In addition, the composition extruded into a sheet and the composition used for the following extrusion and lamination include 3-methyl-2,6 with respect to 100 parts of the total amount of the propylene homopolymer and calcium carbonate used.
-0.05 parts of di-t-butylphenol and 0.05 parts of Irganox 1010 (manufactured by Ciba-Gaiki Co., Ltd.) which is a phenolic stabilizer, Weston 618 (manufactured by BorgWarner Co., Ltd.) which is a phosphorus stabilizer. Product name) 0.05
Parts were compounded. This sheet was heated to a temperature of 140 ° C. and stretched 5 times in the machine direction.

Propylene homopolymer with MFR of 5.0 g / 10 min [Nippon Polychem Co., Novatec PP: MA
4] A composition (a ′) obtained by mixing 90% by weight and 10% by weight of maleic acid-modified polypropylene (modification rate with maleic anhydride of 0.5% by weight) is melt-kneaded by an extruder set at 250 ° C. , Propylene homopolymer having an MFR of 5.0 g / 10 min [Nippon Polychem Co., Ltd., Novatec PP: MA4] 55% by weight and calcium carbonate having an average particle size of 1.5 μm, manufactured by Bihoku Koka Kogyo KK, Soften 1
800] The composition (b ') mixed with 45% by weight of 250
What was melt-kneaded by another extruder set to ℃ was laminated in a die, and this laminate was co-extruded on both sides of the longitudinally 5 × stretched sheet obtained above so that (a ′) was on the outside. Thus, a 5-layer laminate (a '/ b' / c '/ b' / a ') was obtained (hereinafter, abbreviated as "P1").

(2) Oxidation treatment The following corona discharge treatment was applied to the front surface of the 5-layer laminate (P1). The corona discharge processor is Kasuga Electric Co., Ltd.
Using corona discharge treatment machine HFS400F, aluminum electrode, silicone coating roll for the treating roll,
The gap between the electrode and the roll was 2 mm, the line speed was about 30 m / min, and the applied energy density was 100 W · min / m ^{2 for the} treatment.

(3) Application of surface modifier Next, the surface modifier (G1) is applied to the surface subjected to the corona discharge treatment at a coating amount of about 0.2 g / m 2 when dried.
^It was applied so that it would be ^2, and was introduced into the following tenter oven.

(4) Stretching After heating the above-mentioned oxidation-treated and coated five-layer laminate at 155 ° C. in a tenter oven, it was stretched 8.5 times in the transverse direction to form a film having a thickness of 110 μm. 5-layer laminated film (thickness of each layer 6 μm / 23 μm / 52 μm / 23 μm / 6 μ
m) was obtained.

<Examples 2 to 8> Five-layer laminated films were obtained in the same manner as in Example 1 except that the composition shown in Table 1 was used as the surface modifier.

Example 9 Instead of the composition (a ′) used in Example 1, a propylene homopolymer having an MFR of 5.0 g / 10 min [Nippon Polychem Co., Novatec P] was used.
P: MA4] 95% by weight and maleic acid-modified polypropylene 5% by weight (modification rate with maleic anhydride 0.5% by weight) were used, except that the composition (d ') was used.
A five-layer laminated film was obtained by the same operation as above.

Example 10 Instead of the composition (a ') used in Example 1, 5.0 g / 10 min of a propylene homopolymer [Nippon Polychem Co., Novatec PP: MA] was used.
4] 45% by weight, maleic acid modified polypropylene weight 1
A composition in which 0% (modification rate with maleic anhydride of 0.5% by weight) and calcium carbonate having an average particle size of 1.5 μm (manufactured by Bihoku Powder Chemical Co., Ltd., Softon 1800) are mixed.
A 5-layer laminated film was obtained in the same manner as in Example 1 except that (e ′) was used.

Example 11 Instead of the composition (a ') used in Example 1, a propylene homopolymer having an MFR of 5.0 g / 10 min [Nippon Polychem Co., Novatec P].
P: MA4] 90% by weight and maleic acid-modified high-density polyethylene 10% by weight (modification rate with maleic anhydride: 0.
5% by weight), except that the composition (f ′) mixed with
A 5-layer laminated film was obtained by the same operation as in Example 1.

<Example 12> Instead of the composition (a ') used in Example 1, a propylene homopolymer having an MFR of 5.0 g / 10 min [Nippon Polychem Co., Novatec P].
P: MA4] 90% by weight and maleic acid-modified ethylene vinyl acetate copolymer 10% by weight (modification rate with maleic anhydride 0.5% by weight) were used except that a composition (g ′) was mixed. A five-layer laminated film was obtained by the same operation as in Example 1.

Comparative Example 1 It was attempted to apply the surface modifier to the resin sheet used in Example 1 without performing oxidation treatment. However, repellency was generated due to insufficient wettability of the sheet surface and uniform application was impossible. The experiment was interrupted because it could not be performed.

<Comparative Example 2> Instead of the composition (a ') used in Example 1, a propylene homopolymer having an MFR of 5.0 g / 10 min [Nippon Polychem Co., Ltd., Novatec P].
P: MA4] 55% by weight and calcium carbonate having an average particle size of 1.5 μm [Bihoku Koka Kogyo KK, Softon 1800]
A 5-layer laminated film was obtained in the same manner as in Example 1, except that the composition (h ') in which 45% by weight was mixed was used.

Comparative Example 3 Composition (a) used in Example 1
), A propylene homopolymer having an MFR of 5.0 g / 10 min [Nippon Polychem Co., Novatec PP:
MA4] A 5-layer laminated film was obtained in the same manner as in Example 1 except that 100% by weight of the composition (i ′) was used.

<Test Example> Examples 1 to 12 and Comparative Examples 1 to 1
The test described below was performed on each film prepared in 3. [White paper adhesion] Film at 23 ° C, relative humidity 50
After being stored for 3 days in an atmosphere of 100%, the adhesion strength was measured with an adhesion strength measuring device “Internal Bond Tester” (trade name, manufactured by Kumagai Riki Kogyo Co., Ltd.). The principle of measuring the adhesion strength is as follows: an aluminum angle is attached to the upper surface of the sample with cellophane tape on the film-coated surface, the lower surface is also set in the same holder, and a hammer is swung down at an angle of 90 degrees. Impact is applied and the peeling energy at that time is measured. Adhesion strength 1.
The pass level was 0 or higher.

[Ink Transferability] The film was stored for 3 days at a temperature of 23 ° C. and a relative humidity of 50%, and then a printing machine “RI-III type printability tester” (manufactured by Co., Ltd.) Printing ink "Best SP (Ai)" (product name, manufactured by T & K TOKA Co., Ltd.) on Akira Mfg. Co., Ltd. product name, to a thickness of 1.5 g / m ² , 24
Dried at room temperature for hours. Print surface "Macbeth Densitometer"
The Macbeth concentration was measured by (Kormogen Co., Ltd. (USA), trade name). A Macbeth concentration of 1.5 or higher was regarded as a passing level. If it is less than 1.5, the ink transfer is insufficient and it is not practical.

[Ink Adhesion] After printing was carried out in the same manner as in the ink transfer evaluation, the ink adhesion strength of the printed surface was measured by the above-mentioned adhesion strength measuring instrument “Internal Bond Tester”. An ink adhesion strength of 1.0 kg · cm or more was regarded as a pass level. If it is less than 1.0 kg · cm, the ink adhesion strength is insufficient and it is not practical.

[Water resistance evaluation] The printed matter, which was subjected to the same method as the ink transfer evaluation, was dipped in water at 23 ° C. for 3 hours, and then the printing surfaces were bent 30 times in water while bending the printing surfaces. The rubbing property in water of the printed surface was evaluated by rubbing. The evaluation criteria are as follows. 5: Good (the ink is not peeled at all) 4: Good (Ink peeled off a small amount of the ink, but kept at a practical level) 3: Good (Peeled portion was less than 25%) 2: Not good ( The peeled portion was 25% to 75%) 1: No (the peeled portion was more than 75%)

[Evaluation of Antistatic Property] The film was conditioned at a temperature of 23 ° C. and a relative humidity of 50% for 2 hours or more, and then the coated surface of the film was measured with an insulation meter “DSM-8103”.
The surface specific resistance (Ω) was measured by (trade name, manufactured by Toa Denpa Kogyo Co., Ltd.).

Table 1 summarizes the results of the above-mentioned tests performed on the films prepared in Examples 1 to 12 and Comparative Examples 1 to 3.

[0080]

[Table 1]

[0081]

EFFECTS OF THE INVENTION According to the present invention, a thermoplastic resin film having excellent adhesion between the film and the coating film and having printability and antistatic properties can be produced. The thermoplastic resin film obtained by the production method of the present invention is useful as a paper for prints, poster paper, stickers, ornaments and the like.

Front page continuation (51) Int.Cl. ⁷ Identification symbol FI theme code (reference) B29L 9:00 B29L 9:00 C08L 23:26 C08L 23:26 F term (reference) 4F006 AA12 AA55 AA56 AA58 AB24 AB32 AB35 AB37 AB62 AB72 BA01 BA07 CA07 CA10 EA01 EA03 4F073 AA01 AA03 BA06 BB01 CA01 CA21 DA07 GA03 GA11 4F210 AA04 AA04E AA10 AA11 AA11E AA12 AB13 AG01 AG03 AH53 AH81 QA02 QC06 QD08 QD10 QG01 QG15

Claims (16)

[Claims] 1. A thermoplastic resin film comprising a thermoplastic resin film (i) containing an unsaturated carboxylic acid-modified polyolefin resin, the surface of which is oxidized, a surface modifier is applied, and the film is then stretched. Manufacturing method. 2. A thermoplastic resin film (i) comprising a base material layer (ii) made of a thermoplastic resin, and a heat containing the unsaturated carboxylic acid-modified polyolefin resin on at least one surface of the base material layer (ii). Surface layer made of plastic resin (ii
The method according to claim 1, which is a multilayer resin film having i). 3. A thermoplastic resin film (i) comprising a base material layer (ii) made of a longitudinally stretched thermoplastic resin, and the unsaturated carboxylic acid-modified polyolefin resin on at least one surface of the base material layer (ii). The manufacturing method according to claim 1, which is a multilayer resin film having a surface layer (iii) made of a thermoplastic resin contained therein. 4. The unsaturated carboxylic acid of the unsaturated carboxylic acid-modified polyolefin resin is one selected from acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, maleic anhydride and itaconic anhydride. Or 2
It is a mixture of 1 or more types, The manufacturing method in any one of Claims 1-3 characterized by the above-mentioned. 5. The method according to claim 4, wherein the unsaturated carboxylic acid of the unsaturated carboxylic acid-modified polyolefin resin is maleic acid or maleic anhydride. 6. The polyolefin resin of the unsaturated carboxylic acid-modified polyolefin resin is one or more selected from polyethylene, polypropylene, polybutene-1, ethylene-vinyl acetate copolymer and ethylene-propylene copolymer. It is a mixture, The manufacturing method in any one of Claims 1-5 characterized by the above-mentioned. 7. The method according to claim 6, wherein the polyolefin resin of the unsaturated carboxylic acid-modified polyolefin resin is polypropylene. 8. The method according to claim 1, wherein the unsaturated carboxylic acid-modified polyolefin resin has an unsaturated carboxylic acid modification amount of 0.01 to 10% by weight. 9. The production according to claim 1, wherein the thermoplastic resin film (i) has an acid content represented by the following formula of 0.01 to 1.0% by weight. Law. ## EQU1 ## Acid content (% by weight) = M × S ÷ 100 M: Content of unsaturated carboxylic acid-modified polyolefin in thermoplastic resin film (i) (% by weight) S: Modification amount of unsaturated carboxylic acid (weight) %) 10. The production method according to claim 2, wherein the surface layer (iii) has an acid content represented by the following formula of 0.01 to 1.0% by weight. . ## EQU00002 ## Acid content (wt%) = H × S ÷ 100 H: Content of unsaturated carboxylic acid-modified polyolefin resin in surface layer (iii) (wt%) S: Amount of unsaturated carboxylic acid modification (wt) %) 11. The method according to claim 1, wherein the thermoplastic resin film (i) contains an inorganic fine powder and / or an organic filler. 12. The thermoplastic resin film (i) contains a polyolefin-based resin.
1. The method according to any one of 1. 13. The method according to claim 12, wherein the polyolefin resin is a propylene resin. 14. The oxidation treatment is at least one treatment selected from corona discharge treatment, flame treatment, plasma treatment, glow discharge treatment and ozone treatment. Manufacturing method. 15. The surface modifier is selected from polyethyleneimine-based polymers, polyurethane-based polymers, polyacrylic acid ester-based copolymers and polyester-based polymers.
15. The method according to any one of claims 1 to 14, characterized in that it contains one kind or two or more kinds of polymer binders. 16. The method according to claim 1, wherein the surface modifier contains an antistatic polymer.