JPH11342534A - Method for treating surface of thermoplastic resin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a colored spot by oxidizing a surface of a thermoplastic resin film, then coating the surface of the film with a surface modifier, and then orienting the film. SOLUTION: In the thermoplastic resin film, as a thermoplastic resin to be used, an ethylene resin or the like such as a high density polyethylene, an intermediate density polyethylene or the like, a polyolefin resin such as a propylene resin or the like, a polymethyl-1-pentene or the like is used, and a mixture of two or more types can be used. As a surface oxidizing treatment of a base material, at least one type of treating method selected from a corona discharging treatment, a flame treatment, a plasma treatment, a glow discharging treatment and an ozone treatment is used. As a surface modifier, for example, a single or a mixture of two or more components selected from primers of water dispersible resins or the like of an ethyleneimine, a 1-12C alkyl modified polyethyleneimine, a chlorinated polypropylene, and an acrylonitrile- butadiene copolymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to the coloring properties of textile prints by applying a specific oxidation treatment to the surface of a thermoplastic resin film, forming a coating film, and then stretching the film in at least one direction. And to a surface treatment method for obtaining a good thermoplastic resin film. The thermoplastic resin film obtained by the present invention is useful as paper for coloring and printing by printing, poster paper, stickers, decorative articles and the like.

[0002]

2. Description of the Related Art Conventionally, as stickers for outdoor advertising stickers or frozen food containers, the water resistance of such stickers or coated paper as label paper is poor. Coated paper in which the surface of the paper is further covered with a polyester film has been used. recent years,
As such a label paper, a thermoplastic resin film having good water resistance, especially a polyolefin-based synthetic paper, has been attracting attention as a promising material to substitute for the polyester film-coated paper. Such a resin film is a known resin film.
40794, JP-B-49-1782, JP-A-56-
Reference can be made to JP-A No. 118437, JP-A-57-12624 and JP-A-57-56224.

[0003] However, such polyolefin-based synthetic paper is not always satisfactory in printability and processability because the polyolefin as a raw material is non-polar, and therefore, is subjected to an appropriate surface treatment. It is usually used from. As one of such surface treatments, a corona discharge treatment oxidation treatment is applied to the film surface before stretching during the production of a polyolefin synthetic paper, and a coating liquid is further applied to the surface, followed by stretching, and optionally a corona discharge treatment on the surface. A method of performing an oxidation treatment such as a treatment is known.

Japanese Patent Publication No. 57-48587 discloses an improved synthetic method in terms of paper dust trouble, characterized in that an aqueous solution of a paste material that can be spread when dry is coated, and then stretched after drying. A method for producing paper is disclosed.
No. 266417 discloses that a longitudinally stretched film has a thickness of 30 to 1.
A corona treatment of 00 w · min / m ² was performed, and the treated surface was coated with a coating liquid of an ethylene-vinyl alcohol copolymer having an ethylene content of 20 to 45 mol%, dried, stretched in a lateral direction with a tenter, and further stretched for 30 minutes. A method for producing a laminated resin film characterized by performing a corona treatment of about 100 w · min / m ² is disclosed. However, when the entire surface is thinly colored by printing or applying a dyeing solution, coloring is performed. In some cases, spots are noticeable and the commercial value is impaired, and improvement has been desired.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a thermoplastic resin film having a small coloring spot on the surface of the surface of the thermoplastic resin film when the surface colorant is applied.

[0006]

According to the present invention, a thermoplastic resin film (i) is characterized in that the surface of the thermoplastic resin film (i) is oxidized, a surface modifier is applied, and then the film is stretched. ) Is provided.

[0007]

The surface of the thermoplastic resin film (i) before stretching is oxidized, a specific surface modifier is applied, and the film is stretched to make the surface treatment more uniform. Thermoplastic film (i) obtained by
It is presumed that the wettability of the surface dye to be applied and the uniformity at the time of application are improved, and the unevenness of the colorant-coated surface is reduced.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The surface treatment method for a thermoplastic resin film of the present invention comprises oxidizing the surface of a thermoplastic resin film (i), applying a surface modifier, and then stretching. This will be described in detail below. (1) Thermoplastic resin film (i) In the thermoplastic resin film (i) of the present invention, the thermoplastic resin used is an ethylene-based resin such as high-density polyethylene or medium-density polyethylene, or a propylene-based resin. Polyolefin resin, polymethyl-1-
Pentene, ethylene-cyclic olefin copolymer, polyamide-6 resin such as nylon-6, nylon-6,6, nylon-6,10, nylon-6,12, nylon-6, T, polyethylene terephthalate and copolymers thereof And thermoplastic resins such as polyethylene naphthalate and aliphatic polyester, and thermoplastic resins such as polycarbonate, atactic polystyrene, syndiotactic polystyrene, and polyphenylene sulfide. These may be used in combination 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, a propylene resin is preferable in terms of chemical resistance, cost, and the like. As such a propylene-based resin, propylene homopolymer is isotactic or syndiotactic and polypropylene showing various degrees of stereoregularity, propylene as a main component,
A copolymer of this and an α-olefin such as ethylene, butene-1, hexene-1, heptene-1,4-methylpentene-1 is used. This copolymer may be a binary, ternary, or quaternary system, and may be a random copolymer or a block copolymer.

When a propylene homopolymer is used, polyethylene, ethylene
It is preferable to blend 2 to 25% by weight of a resin having a lower melting point than a propylene homopolymer such as a vinyl acetate copolymer. Even if the thermoplastic resin film (i) is a single layer,
Even with a two-layer structure of the base material layer (ii) and the surface layer (iii),
Even in a three-layer structure in which the surface layer (iii) exists on the front and back surfaces of the base layer (ii), a multilayer structure in which another resin film layer exists between the base layer (ii) and the surface layer (iii) May be
Further, those which do not contain the inorganic fine powder or the organic filler or those which do contain it may be used.

When the thermoplastic resin film (i) is a polyolefin resin film, and (i) is a single layer and contains an inorganic fine powder, the polyolefin resin usually contains 40 to 99.5% by weight of inorganic resin. Contains 60 to 0.5% by weight of fine powder, preferably 50 to 50% polyolefin resin.
It contains 97% by weight and 50 to 3% by weight of inorganic fine powder.
When the thermoplastic resin film (i) has a multilayer structure and the base material layer (ii) and the surface layer (iii) contain inorganic fine powder, the base material layer (ii) is usually composed of a polyolefin resin 40 to
99.5% by weight, 60-0.5% by weight of inorganic fine powder, and the surface layer (iii) is a polyolefin resin 25-1.
00% by weight and 75 to 0% by weight of an inorganic fine powder, and preferably the base material layer (ii) is a polyolefin-based resin 50 to 9%.
7% by weight, 50 to 3% by weight of an inorganic fine powder, and the surface layer (iii) has a polyolefin resin of 30 to 97% by weight;
Contains 70 to 3% by weight of inorganic fine powder.

If the amount of the inorganic fine powder contained in the base layer (ii) having a single-layer structure or a multilayer structure exceeds 60% by weight, the stretched resin film is liable to break during the transverse stretching performed after the longitudinal stretching.
75% by weight of inorganic fine powder contained in the surface layer (iii)
If it exceeds, the surface strength of the surface layer after the transverse stretching is low and the paper is liable to peel off. Examples of the inorganic fine powder include calcium carbonate, calcined clay, silica, diatomaceous earth, talc, titanium oxide, barium sulfate, and alumina, and the average particle size is 0.01 to 15 μm, preferably 0.2 to 7 μm.
Is used. If the average particle size is less than 0.01 μm, troubles such as classification and aggregation tend to occur at the time of mixing with the thermoplastic resin, and if it exceeds 15 μm, coloring spots tend to occur.

When the thermoplastic resin film is a polyolefin-based resin film, the organic filler includes
Polyethylene terephthalate, polybutylene terephthalate, polycarbonate, nylon-6, nylon-
6,6, nylon-6, T, melting point higher than the melting point of polyolefin resins such as polymers of cyclic olefins (for example,
170-300 ° C.) or glass transition temperature (for example,
170 ° C. to 280 ° C.). If necessary, stabilizers, light stabilizers, dispersants, lubricants and the like may be added. As a stabilizer, sterically hindered phenol-based, phosphorus-based, amine-based, etc., 0.001 to 1% by weight, as a light stabilizer, sterically hindered amine, benzotriazole-based, benzophenone-based, etc., 0.001 to 1% by weight, inorganic Dispersants of fine powders, for example, silane coupling agents, higher fatty acids such as oleic acid and stearic acid, metal soaps, polyacrylic acid, polymethacrylic acid or their salts, etc.
You may mix | blend 1-4 weight%.

[Formation of Resin Film] The method of forming a thermoplastic resin film is not particularly limited, and various conventionally known methods can be used. As a specific example, a single-layer or multilayer multi-layer connected to a screw-type extruder is used. Cast molding, calender molding, rolling molding, inflation molding, extrusion molding of a mixture of a thermoplastic resin and an organic solvent or oil using a T-die or I-die, or a solvent or oil after calender molding , Molding of a thermoplastic resin from a solution and removal of a solvent. In the case of stretching, various known methods can be used, and specific examples include longitudinal stretching using a difference in peripheral speed between roll groups, and transverse stretching using a tenter oven.

[Resin Film] The thermoplastic resin film of the present invention may be formed by using a thermoplastic resin and being stretched.
Although it may not be stretched, it is necessary that it be stretchable after the surface treatment. Also,
It may or may not contain an inorganic fine powder or an organic filler. Further, a resin layer that 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-based resin film, is a single layer and contains inorganic fine powder, the polyolefin-based resin is 40 to 99.5% by weight, and the inorganic fine powder is 60 to 90%.
By stretching a resin film made of a resin composition containing 0.5% by weight at a temperature lower than the melting point of the polyolefin resin of the above component, preferably at a temperature lower by 3 to 60 ° C., in a uniaxial direction or a biaxial direction, A microporous stretched resin film having fine cracks on the film surface and fine voids (voids) inside the film is obtained.

Further, the thermoplastic resin film (i) has a multilayer structure, and the polyolefin resin 40 of the base material layer (ii) is formed.
A resin film comprising a resin composition containing 100 to 100% by weight and 60 to 0% by weight of an inorganic fine powder at a temperature lower than the melting point of the polyolefin resin of the base layer (ii), preferably 3 to 60 ° C. It is stretched in the machine direction, and then the surface layer (iii) is 25 to 100% by weight of the polyolefin resin.
And a resin film composed of a resin composition containing 75 to 0% by weight of an inorganic fine powder, and a surface layer (iii) as a base material layer (i).
It can be laminated on at least one side of i) and used for surface treatment.

Among the above films, more preferably, a polyolefin resin film containing 5 to 60% by weight of a fine powder such as calcined clay, heavy or light calcium carbonate, titanium oxide and talc is uniaxially stretched. A film in which a number of cracks are formed on the surface to make it semi-transparent or opaque around fine inorganic powder particles, a film in which a resin composition containing the fine powder is further laminated on the surface, No. 60411, JP-A-61-37
No. 48, a raw sheet before stretching used in the production of synthetic paper, which is a laminate in which a polyolefin resin film layer substantially free of inorganic fine powder is formed on the surface layer. And a sheet after longitudinal stretching in sequential biaxial stretching. The thickness of the resin film used in the preceding surface treatment used in the present invention can be appropriately selected in accordance with the stretching ratio and the thickness of the film required after stretching, and is generally 20 to 4000 μm, preferably 100 Those having a range of up to 3000 μm are used.

[Surface Oxidation Treatment] The surface oxidation treatment of the base material is at least one treatment method selected from corona discharge treatment, flame treatment, plasma treatment, glow discharge treatment, and ozone treatment, preferably corona treatment. , Frame processing. The processing amount is 600 ~
12,000 J / m ² (10-200 W · min / m ² ),
Preferably 1200 to 9000 J / m ² (20 to 180
W · min / m ² ). 600 J / m ² (10 W / min /
If it is less than m ² ), the effect of the corona discharge treatment will be insufficient, and cissing will occur during the subsequent application of the surface modifier, resulting in 12,000
Since 0J / m ² (180W · min / m ²⁾ effect of the treatment is greater than is the plateau ^{12, 000J / m 2 (180W} · min / m ²⁾ is a fully below. In the case of frame processing,
000-200,000 J / m ² , preferably 20,000
00 to 100,000 J / m ² is used. 8:00
If it is less than 0 J / m ² , the effect of the frame processing is insufficient.
During the subsequent application of the surface modifier, repulsion occurs, and 200,
If it exceeds 2,000 J / m ² , the effect of treatment will reach a plateau, so
Less than or equal to 00,000 J / m ² is sufficient.

[Surface Modifier] The surface modifier used in the present invention is selected from the following primers, and may be used alone or as a mixture of two or more components. If necessary, a combination with the following crosslinking agent and antistatic polymer is also possible. Primers Examples of the primer include polyethyleneimine, alkyl-modified polyethyleneimine having 1 to 12 carbon atoms,
Polyethyleneimine-based polymers such as poly (ethyleneimine-urea) and ethyleneimine adduct of polyamine polyamide and epichlorohydrin adduct of polyamine polyamide, acrylamide-acrylate copolymer, acrylamide-acrylate-methacryl Acid ester copolymers, polyacrylamide derivatives,
Acrylate ester polymers such as oxazoline group-containing acrylic ester polymers, polyvinyl pyrrolidone, water-soluble resins such as polyethylene glycol, polyvinyl acetate, polyurethane, ethylene-vinyl acetate copolymer,
Water-dispersible resins such as polyvinylidene chloride, chlorinated polypropylene, and acrylonitrile-butadiene copolymer can be used.

Of these, preferred are polyethyleneimine-based polymers, urethane resins, polyacrylate copolymers and the like, more preferred are polyethyleneimine-based polymers, and further preferred are those having a polymerization degree of 20 to
3,000 polyethyleneimine, an ethyleneimine adduct of polyamine polyamide, or a modified polyethyleneimine obtained by modifying them with an alkyl halide, alkenyl halide, cycloalkyl halide, benzyl halide group having 1 to 24 carbon atoms It is.

Crosslinking Agent By adding a crosslinking agent to the above-mentioned primer, the coating film strength and water resistance can be further improved. Examples of the crosslinking agent include epoxy compounds such as glycidyl ether and glycidyl ester, epoxy resins, and water-dispersible resins such as isocyanate, oxazoline, formalin, and hydrazide. The amount of the crosslinking agent added
Usually, 1 to 50 parts by weight per 100 parts by weight of the primer
The range is 0 parts by weight.

Antistatic Polymer By adding an antistatic polymer to the above-mentioned primer, it is possible to reduce troubles due to adhesion of dust and charging during printing. Examples of the antistatic polymer include a water-soluble nitrogen-containing acrylic polymer and a styrene-maleic anhydride copolymer, and a nitrogen-containing acrylic polymer is particularly preferable. (A) Nitrogen-containing acrylic polymer The above-mentioned water-soluble nitrogen-containing acrylic polymer imparting antistatic properties may be a tertiary nitrogen or quaternary nitrogen-containing acrylic polymer. Examples of the monomer include those represented by the following chemical formulas (a) to (d).

Chemical formula (A)

Embedded image

Chemical formula (b)

Embedded image _{^{Wherein, -CH 2 N + R 2 R}} 3 R 4 X - group -CR ¹ =
It is located at the ortho, meta or para position on the aromatic ring with respect to the CH ₂ group, and is preferably bonded at the para position. ]

Chemical formula (C)

Embedded image

Chemical formula (D)

Embedded image It is at least one kind selected from (ii), (ii) or (ii), and preferably (ii).

In each of the above chemical formulas (a) to (d), R
¹ is a hydrogen atom or a methyl group, and R ² and R ³ are each a lower alkyl group (particularly having 1 to 4 carbon atoms, especially 1 to 4 carbon atoms).
2), R ⁴ is a saturated or unsaturated alkyl or cycloalkyl group having 1 to 22 carbon atoms, X ⁻ is a quaternized N ⁺ counter anion (for example, halide (especially chloride)), and M is an alkali metal ion (especially Sodium, potassium, or lithium) and A represents an alkylene group having 2 to 6 carbon atoms.

The above chemical formulas (a), (b), (c),
The polymer of the quaternary nitrogen-containing monomer represented by (d) is obtained by polymerizing the quaternary nitrogen-containing monomer of the precursor and then cationizing agent such as alkyl halide, dimethyl sulfate, monochloroacetate and the like. Needless to say, the polymer can be present in the polymer by quaternization. In the present invention, the antistatic agent needs to be water-soluble, but not excessively water-soluble is not desirable. Therefore, (A)
The quaternary nitrogen-containing polymer as a component is preferably a copolymer with a hydrophobic monomer. Examples of the hydrophobic monomer include styrene or its nucleus or side chain substituent, acrylic or methacrylic acid ester, vinyl halide, and the like.

<Suitable Antistatic Polymer> In the present invention, a particularly preferred antistatic polymer of the component (A) is a copolymer of the following components (a) to (c). (A) Component: 20 to 40% by weight of quaternary nitrogen-containing monomer represented by chemical formulas (A) to (D) (b) Component: 60 to 80% by weight of monomer represented by the following general formula Component (c): other hydrophobic vinyl monomer 0 to 20% by weight

[0030]

Embedded image [In the formula, R ¹ represents a hydrogen atom or a methyl group, R ⁵ represents an alkyl group having 1 to 22 carbon atoms, an aralkyl group having 7 to 22 carbon atoms, or a cycloalkyl group having ⁵ to 22 carbon atoms. ]

<Most Suitable Antistatic Agent Polymer> In the present invention, the most preferred antistatic agent polymer of the component (A) is
(A) The quaternary nitrogen-containing monomer of the component is the monomer (a) described above.
In which X ⁻ is Cl ⁻ . Also, (A)
The components are, as described in JP-A-6-25447, (a ') a monomer represented by the following general formula: 30 to 70% by weight.

[0032]

Embedded image Wherein A represents —O— or —NH—, R ¹ represents a hydrogen atom or a methyl group, and R ⁶ has 2 to 4 carbon atoms.
Alkylene group or -CH ₂ -CH of (OH) -CH
Represents _2- , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ may be the same or different and represent an alkyl group having 1 to 3 carbon atoms, and R ¹¹ represents an alkyl group having 1 to 10 carbon atoms. Represents a group or an aralkyl group having 7 to 10 carbon atoms, and X represents a chlorine atom, a bromine atom or an iodine atom. (B) 30 to 70% by weight of a monomer represented by the following general formula:

[0033]

Embedded image [Wherein, R ¹ represents a hydrogen atom or a methyl group, R ⁵ represents an alkyl group having 1 to 22 carbon atoms, an aralkyl group having 7 to 22 carbon atoms, or a cycloalkyl group having ⁵ to 22 carbon atoms. Component (c): A quaternary ammonium salt type copolymer obtained by copolymerizing 0 to 40% by weight of another hydrophobic vinyl monomer is also preferable. Specific examples of the monomer (a ′) include the following general formulas such as dimethylaminoethyl acrylate, diethylaminoethyl acrylate and their methacrylate equivalents, dimethylaminopropylacrylamide, and their methacrylate equivalents. The tertiary amine-containing monomer represented by (IV) is modified with a modifier represented by the following general formula (VI) such as 3-chloro-2-hydroxypropyltrimethylammonium chloride before or after polymerization. Can be obtained.

Formula (IV)

Embedded image Wherein A represents —O— or —NH—, R ¹ represents a hydrogen atom or a methyl group, and R ⁶ has 2 to 4 carbon atoms.
Alkylene group or -CH ₂ -CH of (OH) -CH
Represents _2- , and R ⁷ and R ⁸ may be the same or different and represent an alkyl group having 1 to 3 carbon atoms. ]

Formula (VI)

Embedded image [Wherein, R ⁹ and R ¹⁰ may be the same or different and represent an alkyl group having 1 to 3 carbon atoms, and R ¹¹ represents an alkyl group having 1 to 10 carbon atoms or 7 carbon atoms. Represents an aralkyl group of 10 to 10, n is an integer of 1 to 3, and X represents a chlorine atom, a bromine atom or an iodine atom. ]

The hydrophobic monomer unit of the component (b) includes methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, tertiary butyl (meth) acrylate, Cyclohexyl (meth) acrylate, 2
-Ethylhexyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate,
Alkyl (meth) such as stearyl (meth) acrylate
Acrylates can be mentioned. Further, as other monomer units of the component (c) copolymerizable with the components (a) or (a ′) and (b) used as necessary,
Examples include hydrophobic monomers such as styrene, vinyltoluene, and vinyl acetate, and hydrophilic monomers such as vinylpyrrolidone and (meth) acrylamide.

As a polymerization method for obtaining a copolymer which is a water-soluble antistatic agent of the component (A), known polymerization methods such as bulk polymerization, solution polymerization, emulsion polymerization and the like using a radical initiator are employed. can do. Among these, a preferred polymerization method is solution polymerization, which is carried out by dissolving each monomer in a solvent, adding a radical polymerization initiator, and heating and stirring under a nitrogen stream. The solvent is preferably water, alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol, and the like, and these solvents may be used in combination. As the polymerization initiator, peroxides such as benzoyl peroxide and lauroyl peroxide, and azo compounds such as azobisisobutyronitrile and azobisvaleronitrile are suitably used. The concentration of the monomer is usually 10 to 60% by weight, and the concentration of the polymerization initiator is usually 0.1 to 10% by weight based on the monomer.

The molecular weight of the quaternary ammonium salt copolymer is determined by the polymerization temperature, the type and amount of the polymerization initiator, the amount of the solvent used,
The level can be set to an arbitrary level depending on polymerization conditions such as a chain transfer agent. Generally, the molecular weight of the resulting polymer is 1,000
0 to 1,000,000, but especially 1,000 to
A range of 500,000 is preferred. The amount of the antistatic polymer is usually based on 100 parts by weight of the primer.
It is 10 to 500 parts by weight, preferably 30 to 250 parts by weight. When the amount is less than 10 parts by weight, the antistatic effect is insufficient, and when it exceeds 500 parts by weight, the adhesion of the printing ink may be insufficient.

The surface modifier of the present invention may contain the following optional components as required. The amount of the optional component is usually 50 parts by weight or less based on 100 parts by weight of the primer. Optional component 1: alkali metal salt or alkaline earth metal salt As the alkali metal salt or alkaline earth metal salt, water-soluble inorganic salts such as sodium carbonate, sodium hydrogencarbonate, potassium carbonate, sodium sulfite, and other alkaline salts; And sodium chloride, sodium sulfate, sodium nitrate, sodium tripolyphosphate, sodium pyrophosphate, ammonium alum and the like. Optional Component 2: The surface modifier may further include a surfactant, an antifoaming agent, a water-soluble or water-dispersible fine powder substance, and other auxiliaries.

[Formation of Surface Modified Layer] Each component of the surface modified layer is used after being dissolved in water or a hydrophilic solvent such as methyl alcohol, ethyl alcohol, or isopropyl alcohol. Usually used in form. The solution concentration is usually about 0.05 to 20% by weight, preferably about 0.1 to 10% by weight. 0.0
If the amount is less than 5% by weight, it is necessary to devise a step of drying the water or extend the drying time. If the amount is more than 20% by weight, coating unevenness tends to occur. The coating method is performed by a roll coater, blade coater, bar coater, air knife coater, size press coater, gravure coater, reverse coater, die coater, lip coater, spray coater, etc. Through which excess water and hydrophilic solvent are removed. Coating amount is 0.005 to 10 g as solids after drying
/ M ^2, and preferably more preferably ^{0.01~1g / m 2 0.01~0.6g / m 2} . 0.005g / m
^If it is less than ² , the effect of the primer is insufficient, and 10 g /
If it exceeds m ² , coating unevenness may be conspicuous and the uniformity of coloring may be deteriorated.

[Stretching] For the stretching, conventionally known various methods can be used. As a specific example, in the case of an amorphous resin, the temperature is equal to or higher than the glass transition temperature of the thermoplastic resin to be used, and in the case of a crystalline resin. Can be carried out in a known temperature range suitable for each thermoplastic resin from the glass transition point temperature of the non-crystalline portion to the melting point of the crystalline portion or less, the longitudinal stretching using the peripheral speed difference of the roll group, a tenter oven. Examples include transverse stretching, rolling, and simultaneous biaxial stretching using a combination of a tenter oven and a linear motor. The stretching ratio is not particularly limited, and is appropriately selected depending on the purpose and the characteristics of the thermoplastic resin to be used. For example, when polypropylene or a copolymer thereof is used as the thermoplastic resin, when it is stretched in one direction, it is about 1.2 to 12 times, preferably 2 times.
10 to 10 times, and in the case of biaxial stretching, 1.5 times the area ratio.
６０60 times, preferably 10 to 50 times. When using other thermoplastic resins, when stretched in one direction, it is 1.2 to 10 times, preferably 2 to 5 times, and in the case of biaxial stretching, it is 1.5 to 20 times in area magnification, preferably Is 4 ~
It is 12 times. Further, a heat treatment at a high temperature is performed as necessary.

The stretching temperature is 2 to 60 ° C. lower than the melting point of the thermoplastic resin to be used. When the resin is a propylene homopolymer (melting point: 155 to 167 ° C.), the stretching temperature is 110 to 164.
110 ° C. for high-density polyethylene (melting point 121 to 134 ° C.) and 104 to 115 ° C. for polyethylene terephthalate (melting point 246 to 252 ° C.), which are appropriately selected depending on the stretching process and conditions. The stretching speed is from 20 to 350 m / min. When the thermoplastic resin film contains an inorganic fine powder or an organic filler, fine cracks are formed on the film surface and fine pores are formed inside the film. The thickness of the stretched thermoplastic resin film (i) is 20 to 500 μm, preferably 3 to 500 μm.
5 to 300 μm.

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

(Equation 2) (Coloring) The printing paper having the colorant receiving layer formed on the surface of the thermoplastic resin film (i) thus obtained can be colored uniformly. As a coloring method, various known methods such as coating with a spray brush or a spray coater, silk screen, printing, immersion, aqueous gravure, and roll transfer can be used. Among them, printing is preferable. These coloring methods are described in "Dye Handbook" 79-2.
48 pages, Synthetic Organic Chemistry Association, published by Maruzen Co., Ltd., 19
1970, “Dyeing and Processing of Chemical Fibers”, pp. 337-359,
Edited by The Society of Polymer Science, published by Jinjinshokan Co., Ltd., 1966,
Can be used. Colored thermoplastic resin film is easy to identify for each paper by color,
It is possible to give a picture by dyeing. In addition to coloring and dyeing, it can be used not only for letterpress printing, gravure printing, flexographic printing, solvent-based offset printing, but also for ultraviolet-curable offset printing.

[0044]

EXAMPLES The present invention will be described more specifically with reference to the following examples. The raw materials and evaluation methods used in the examples are as follows. Further, “parts” in the component mixing ratio indicates “parts by weight”. [I] Surface modifier (1) Preparation of surface modifiers (G1 to G3) Synthesis of modified ethyleneimine-based polymer Alkyl-modified ethyleneimine-based polymer (F1) Stirrer, reflux condenser, thermometer, and nitrogen gas In a four-necked flask provided with an inlet, polyethyleneimine “Epomin P-1000” (trade name; degree of polymerization: 16) manufactured by Nippon Shokubai Co., Ltd.
100) of a 25% by weight aqueous solution, 10 parts of n-butyl chloride and 10 parts of propylene glycol monomethyl ether were stirred under a nitrogen stream, and a denaturing reaction was carried out at a temperature of 80 ° C. for 20 hours to give a butyl-modified polyethyleneimine aqueous solution. I got Water was added to this solution to obtain a solution having a concentration of 25% by weight of butyl-modified polyethyleneimine (hereinafter, referred to as a solution).
Abbreviated as "F1". ).

(G1) 5 parts of the above aqueous solution (F1) was added to 100 parts of water, and the mixture was stirred and mixed to obtain a surface modifier (G1).
Was prepared. (G2) 6 parts of an aqueous solution of polymin SN (manufactured by BASF, trade name, solid content: 24% by weight, hereinafter abbreviated as "F2") based on 100 parts of water, based on a polyethyleneimine polymer. In addition, the mixture was stirred and mixed, and the surface modifier (G
2) was prepared.

(G3) 35 parts of dimethylaminoethyl methacrylate, 20 parts of ethyl methacrylate, 20 parts of cyclohexyl methacrylate were placed in a four-necked flask equipped with a reflux condenser, a thermometer, a glass tube for purging nitrogen, and a stirrer. Then, 25 parts of stearyl methacrylate, 150 parts of ethyl alcohol and 1 part of azobisisobutyronitrile were added, and a polymerization reaction was carried out at 80 ° C. for 6 hours under a nitrogen stream. Next, 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. Ethyl alcohol was distilled off while water was added dropwise to obtain a final solid content. 30% quaternary ammonium salt type copolymer (abbreviation H
1) was obtained. This is an alkyl acrylate polymer containing a group represented by the following general formula in the molecular chain.

[0047]

Embedded image 5 parts of the aqueous solution (F1) and 3 parts of the quaternary ammonium salt type copolymer (H1) were added to 100 parts of water, and mixed and stirred to prepare a surface modifier (G3).

Example 1 (1) Resin Sheet Production Example 1 (P1) 15 wt% of heavy calcium carbonate having an average particle size of 1.5 μm was added to polypropylene having a melt flow rate (MFR) of 0.8 g / 10 min. The compounded composition (c ′) was kneaded by an extruder set at 240 ° C., extruded into a sheet, and cooled by a cooling device to obtain a non-stretched sheet. The composition extruded into a sheet and the composition used for the following extrusion and lamination were 3-methyl-to-polypropylene and calcium carbonate in a total amount of 100 parts.
0.05 parts of 2,6-di-t-butylphenol, 0.05 parts of Irganox 1010 (trade name, manufactured by Ciba-Gaiky) as a phenolic stabilizer, and Weston 618 (BorgWarner Co., Ltd.) as a phosphorus-based stabilizer ) Product name)
0.05 part was blended. This sheet was heated to a temperature of 140 ° C. and stretched 5 times in the machine direction.

50% by weight of polypropylene having an MFR of 4.0 g / 10 min and 5% by weight of maleic acid-modified polypropylene
(A ′) obtained by mixing and kneading a composition (a ′) prepared by mixing an extruder set at 250 ° C. with an MFR of 4.0 g / 10
(B ′) obtained by mixing 55% by weight of polypropylene and 45% by weight of calcium carbonate having an average particle size of 1.5 μm by melt kneading with another extruder set at 250 ° C., and laminated in a die. This laminate was co-extruded on both sides of the 5-fold stretched sheet obtained above so that (a ′) was on the outside, and a five-layer laminate (a ′ / b ′ / c ′ / b ′ /
a ′) was obtained (hereinafter abbreviated as “P1”).

(2) Oxidation Treatment The surface of the five-layer laminate (P1) was subjected to the following corona discharge treatment. Corona discharge treatment machine is Kasuga Electric
Using a corona discharge treatment machine HFS400F made of aluminum, using a silicone-coated roll for the aluminum electrode and treater roll,
The treatment was performed at a line speed of about 30 m / min and an applied energy density of 100 W · min / m ² with the gap between the electrode and the roll being 2 mm.

(3) Application of Surface Modifier Next, the surface treated with the corona discharge was treated with the surface modifier (G1) described in the section of “Preparation of Surface Modifier”.
Was applied so that the coating amount at the time of drying was about 0.2 g / m ^2, and was led to the following tenter oven. (4) Stretching After heating the oxidized and coated five-layer laminate at 155 ° C. in a tenter oven, it is stretched by a factor of 8.5 in the horizontal direction to form a five-layer laminate having a thickness of 110 μm. Film (thickness of each layer: 6 μm / 23 μm / 52 μm / 23 μm / 6 μ
m). The uniformity of the colorant during coating, the water resistance of the colored surface, the ink adhesion, and the like were evaluated by the methods described below.

[Evaluation] (1) Uniformity at the time of applying a colorant A colorant was prepared by the following method and used for evaluating the uniformity at the time of applying a colorant. 0.1 g of sodium hydroxide (manufactured by Wako Pure Chemical Industries, Ltd., reagent grade) was completely dissolved in 40 g of water, the temperature was brought to 50 ° C. in a hot water bath, and 1 g of ethanol was further added.
Then, while stirring, 0.5 g of tetrabromophenolsulfonephthalein (a reagent grade, manufactured by Wako Pure Chemical Industries, Ltd.) as a dye was dissolved little by little, and after the addition was completed,
The mixture was stirred at 50 ° C. for 4 hours to prepare a dye stock solution.

While stirring in 1060 g of water at 80 ° C. in a hot water bath, polyvinyl alcohol 500 (manufactured by Wako Pure Chemical Industries, Ltd., fully saponified, average degree of polymerization of about 400 to 6) was used as a paste.
00, saponification degree 96 mol% or more) 118 g and polyvinyl alcohol 500 (manufactured by Wako Pure Chemical Industries, Ltd., complete saponification type, average polymerization degree about 400 to 600, saponification degree 96 mol%)
118 g) was dissolved little by little, and after the addition was completed, the temperature was raised to 90 ° C., and the mixture was stirred for 2 hours to prepare a paste solution. The glue solution is allowed to cool to room temperature, and then stirred with water 230
g, 2.5 g of 2-butoxyethanol (Wako Pure Chemical Industries, Ltd., reagent grade, purity 98% or more), and 3.3 g of sodium sulfosuccinate bis (2-ethylhexyl) ester as a surfactant, followed by stirring for 2 hours After that, the above dye stock solution was gradually added with further stirring, and
After stirring for a minute, a colorant was prepared.

This dye was applied to the film surface of Example 1
It was applied to a thickness of about 18.3 μm using a Mayer bar (# 8) and dried at room temperature for 1 hour to obtain a film having a surface coated with a colorant. The resulting film was visually observed for color unevenness on the coated surface, and evaluated on the following three levels. 3: The coloring unevenness is partially slight but not so noticeable. 2: Color unevenness is partially present and conspicuous. 1: The coloring unevenness is conspicuous on the entire surface. Example 1 was at a level of 3. The results are shown in Table 1. (2) Color Density of Colored Surface The color density of the above colored surface was measured as a light reflection density (Macbeth density) using a Macbeth densitometer (manufactured by Colmorgen, USA). Example 1 was at a level of 0.18.

<Comparative Example 1> The uncolored Macbeth concentration of the film produced in Example 1 was measured without applying a colorant, and it was 0.02. The results are shown in Table 1. <Comparative Example 2> A film was prepared and evaluated in the same manner as in Example 1 except that the application of the surface modifier was not performed. The results are shown in Table 1. <Comparative Example 3> A film was produced in the same manner as in Example 1 except that the surface modifier G1 was applied without performing corona discharge treatment before stretching, but the film was repelled when the surface modifier was applied. No further evaluation was performed because of the occurrence of. The results are shown in Table 1.

Comparative Example 4 A laminated resin sheet was manufactured in the same manner as in Example 1, and the corona treatment amount before stretching was 5 W · min / m ^2.
The surface modifier G1 was applied, but repelling occurred, and a uniform applied surface was not obtained. Therefore, the subsequent evaluation was not performed. The results are shown in Table 2. <Examples 2 to 3> The surface modifier was (G2) or (G
3), and a film was produced in the same manner as in Example 1 except that the coating amount after drying was changed as shown in Table 2.
Surface treatment and evaluation were performed. Table 2 shows the main points and evaluation results of the examples.

Example 4 The oxidation treatment before stretching was changed to a corona treatment amount of 40 W · min / m ^2, and the coating amount of the surface modifier (G1) after drying was 0.4 g / m ² . Except for Example 1
A film was produced, surface treated and evaluated in the same manner as described above.
The results are shown in Table 2. <Example 5> Oxidation treatment before stretching was performed with a corona treatment amount of 180 W
A film was produced, surface treated and evaluated in the same manner as in Example 1 except that the film was changed to minutes / m ² . The results are shown in Table 2.

<Example 6> Five-layer laminate (P1) before stretching
FLYNN BURNE
R) manufactured by Furin F3000 Direct Flame Plasma Processor, using propane as the combustion gas, at a line speed of 40 m / min and an applied energy of 37,700 J / m ^2.
A film was produced, surface-treated and evaluated in the same manner as in Example 1 except that the frame treatment was performed. Table 3 shows the evaluation results. Example 7 A film was produced in the same manner as in Example 6, except that the applied energy of the frame treatment before stretching was 28,000 J / m ² . Table 3 shows the evaluation results. <Embodiment 8> The applied energy of the frame processing is set to 6060.
A film was produced in the same manner as in Example 6, except that 0 J / m ² and the line speed were 70 m / min. Table 3 shows the evaluation results.

Example 9 The production of the resin sheet was changed as shown in Production Example 2 below, the corona treatment amount was 90 W · min / m ² , and the surface modifier was G3 (coating amount after drying). 0.3
g / m ² ), except that the film was manufactured and evaluated in the same manner as in Example 1. The following was used as a resin sheet before stretching. Production Example 2 of Resin Sheet (P2) Polypropylene having an MFR of 4.0 g / 10 min in the composition of A ′ in Production Example 1 of the resin sheet before transverse stretching was ethylene-propylene random copolymer having an MFR of 10 g / 10 min. Except for changing to 5, the same as in Production Example 1 (P1)
A layer laminate was obtained. Table 3 shows the evaluation results.

Example 10 The following was used as a resin sheet before stretching. Production Example 3 of Resin Sheet Before Lateral Stretching (P3) Composition (c ′) in which 15% by weight of heavy calcium carbonate having an average particle size of 1.5 μm was blended with polypropylene having a melt index (MFR) of 0.8 g / 10 minutes. Was kneaded by an extruder set at 250 ° C., extruded into a sheet, and cooled by a cooling device to obtain a single-layer unstretched sheet.
This was heated to a temperature of 140 ° C., stretched 4.5 times in the longitudinal direction by utilizing the peripheral speed difference between the rolls, and dried under the same conditions as in Example 1 to apply the surface modifier G1. 0.2 g / m ²
After drying in a drying oven, the film was heated to 155 ° C. in a tenter oven and stretched 9 times in the transverse direction to obtain a biaxially stretched film having a thickness of 95 μm. This film was subjected to a corona discharge treatment under the conditions of 90 W · min / m ² . Table 3 shows the evaluation results.

<Comparative Example 5> Without performing the oxidation treatment before stretching,
The same operation as in Example 9 was performed except that G3 was used as the surface modifier, but evaluation was not performed because repelling occurred when the surface modifier was applied. <Comparative Example 6> The same operation as in Example 10 was performed except that the oxidation treatment before stretching was not performed and the surface modifier was changed to G1, but repelling occurred when the surface modifier was applied. No evaluation was performed.

[0062]

[Table 1]

[0063]

[Table 2]

[0064]

[Table 3]

[0065]

As described above, according to the present invention, it was possible to provide a thermoplastic resin film having good uniformity of coloring with an aqueous dye.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29L 9:00

Claims (10)

[Claims] 1. A method for treating the surface of a thermoplastic resin film (i), comprising oxidizing the surface of the thermoplastic resin film (i), applying a surface modifier, and then stretching the film. 2. A thermoplastic resin film (i) stretches a base material layer (ii) made of a thermoplastic resin in a longitudinal direction, and then a surface layer (iii) made of a thermoplastic resin is formed on at least one surface of the base material layer (ii).
The surface treatment according to claim 1, wherein the surface of the multilayer resin film is obtained by oxidizing the surface, applying a surface modifier, and then performing transverse stretching. Method. 3. A thermoplastic resin film (i) comprising a base layer (ii) made of a thermoplastic resin and a surface layer (iii) made of a thermoplastic resin laminated on at least one surface of the base layer (ii). The surface treatment method according to claim 1, wherein the surface of the obtained multilayer resin film is subjected to an oxidation treatment, a surface modifier is applied, and then longitudinal stretching is performed. 4. A thermoplastic resin film (i) comprising 40 to 100% by weight of a thermoplastic resin and 60 to 0% by weight of an inorganic fine powder.
% Of the base material layer (ii) and the thermoplastic resin 25 to 10
4. The surface treatment method according to claim 2, wherein the multilayer resin film comprises a surface layer (iii) containing 0 wt% and 75 to 0 wt% of inorganic fine powder. 5. The surface treatment method according to claim 1, wherein the thermoplastic resin film (i) has a porosity represented by the following formula of 10 to 60%. . (Equation 1) 6. The thermoplastic resin film (i) is made of a polyolefin-based resin.
The surface treatment method according to any one of the above. 7. The surface treatment method according to claim 6, wherein the polyolefin-based resin is a propylene-based resin. 8. The method according to claim 1, wherein the oxidation treatment is at least one treatment selected from a corona discharge treatment, a flame treatment, a plasma treatment, a glow discharge treatment, and an ozone treatment. Surface treatment method. 9. Corona treatment in which the oxidation treatment is performed at 10 to 200 W · min / m ² , or 8,000 to 200,000
9. The surface treatment method according to claim 8, wherein the frame treatment is performed at J / m < ² >. 10. The surface treatment method according to claim 1, wherein the surface modifier is a polyethyleneimine-based primer.