JP5052759B2 - Surface treatment method for thermoplastic resin film and thermoplastic resin film - Google Patents

Description

  The present invention relates to a surface treatment method for a thermoplastic resin film. More specifically, the present invention relates to a surface treatment method that can provide a thermoplastic resin film having good offset printing suitability and melt heat transfer printer suitability, and excellent printed paper water resistance and antistatic properties.

  Conventionally, as a sticker for outdoor advertising stickers and frozen food containers, the coated paper, which is the sticker or label paper, has poor water resistance. Coated paper coated with a polyester film was used. In recent years, thermoplastic resin films with good water resistance, especially polyolefin-based synthetic papers have attracted attention as promising materials to replace polyester film-coated paper (for example, Patent Documents 1 to 5).

However, because such polyolefin synthetic paper is a non-polar polyolefin as the raw material, it is suitable for printing such as offset printing, gravure printing, letterpress printing, flexographic printing, and printers such as fusion thermal transfer printers and sublimation thermal transfer printers. Suitability is not always satisfactory. For this reason, it is common to use it after performing an appropriate surface treatment. For example, a method is known in which the surface of a polyolefin film before stretching is subjected to an oxidation treatment such as corona discharge, further coated after applying a coating solution on the surface, and then further subjected to an oxidation treatment such as corona discharge in some cases. Yes. Specifically, the longitudinally stretched film is subjected to a corona discharge treatment of 30 to 100 W · min / m ² , and a coating solution of an ethylene-vinyl alcohol copolymer having an ethylene content of 20 to 45 mol% is coated on the treated surface. A method for producing a laminated resin film has been proposed, characterized in that the film is stretched in the transverse direction with a tenter after drying, and further subjected to a corona discharge treatment of 30 to 100 W · min / m ² (Patent Document 6). However, the laminated resin film to be produced lacks suitability for fusion thermal transfer and offset printing, and improvement is desired.

  As another method for improving the printability, for example, by forming an adhesive layer containing a copolymer of a specific amount of ethylene and a functional group-containing ethylenically unsaturated compound on a polymer film, letterpress printing A method for producing an easily adhesive film excellent in suitability is also known (Patent Documents 7 and 8). However, the easily-adhesive film produced by this method is also insufficient in both printability for offset printing and melt heat transfer suitability, and improvement is desired.

  As yet another method, an olefin copolymer (a) to which an unsaturated carboxylic acid or an anhydride thereof is bonded is converted into a nonionic surfactant, a nonionic water-soluble polymer, a cationic surfactant, and a cationic A resin aqueous dispersion dispersed in water using at least one selected from the group consisting of water-soluble polymers as the dispersant (b), wherein the weight per solid content of (a) / (b) There is also a method for producing an image receiving film for thermal transfer by applying an aqueous resin dispersion having a ratio of 100/1 to 100/30 and an average particle diameter of 5 μm or less onto a thermoplastic resin film and drying it. It has been proposed (Patent Document 9). However, the manufactured thermal transfer image receiving film also has good melt thermal transfer suitability, but there are problems with antistatic properties and offset print suitability, leaving room for improvement.

  As an improved technique of this method, printing and thermal transfer are carried out by applying a coating solution obtained by adding a polyethyleneimine resin, a crosslinking agent, and an antistatic polymer to the above-mentioned aqueous resin dispersion on a thermoplastic resin film and drying it. A method for producing an image receiving film has also been proposed (Patent Document 10). However, the manufactured film has good melt heat transfer suitability and antistatic property, but there is a problem in water resistance of the printed matter in offset printing, and there is still room for improvement.

  In addition, a method for producing a thermoplastic resin film by applying the aqueous resin dispersion to an oxidized thermoplastic resin film before stretching and stretching has also been proposed (Patent Document 11). However, the thermoplastic resin film produced has good melt heat transfer suitability and water resistance during printed printing, but has a problem in antistatic properties.

Japanese Examined Patent Publication No. 46-40794 Japanese Patent Publication No.49-1782 Japanese Patent Laid-Open No. 56-118437 JP-A-57-12642 JP-A-57-56224 JP-A-7-266417 JP-A-11-323267 JP 11-342565 A JP 2001-219661 A JP 2002-113959 A JP 2003-73490 A

  An object of the present invention is to provide a thermoplastic resin film excellent in melt thermal transfer suitability, offset print suitability, and water resistance of printed matter, and further excellent in antistatic properties, and a method for producing the same.

The above purpose is
[1] A first step of oxidizing the surface of the thermoplastic resin film,
[2] A second step of applying a surface treatment agent containing the following component (A) and component (B) to the surface of the oxidized thermoplastic resin film, and [3] a thermoplastic resin coated with the surface treatment agent A third step of stretching the film;
It was achieved by the surface treatment method for a thermoplastic resin film of the present invention characterized by comprising:

Ingredient (A):
A group consisting of a nonionic surfactant, a nonionic water-soluble polymer, a cationic surfactant, and a cationic water-soluble polymer comprising an olefin copolymer (a) to which an unsaturated carboxylic acid or an anhydride thereof is bound. An aqueous dispersion in which at least one selected from the above is used as the dispersant (b) and dispersed in water, wherein the ratio of the weight per solid content of (a) / (b) is 100/1 to 100 / 30 and an aqueous resin dispersion having an average particle size of 5 μm or less

［上式中、Ａは−Ｏ−もしくは−ＮＨ−を表し、Ｒ¹は水素原子若しくはメチル基を表し、Ｒ²は炭素数が１〜１８のアルキレン基若しくは−ＣＨ₂−ＣＨ（ＯＨ）−ＣＨ₂−を表し、Ｒ³およびＲ⁴は同一であっても異なっていても良く、炭素数が１〜３のアルキル基を表す。Ｒ³およびＲ⁴が結合する窒素原子は四級アンモニウム塩になっていてもよい。］ Ingredient (B):
Nitrogen-containing acrylic polymer having a structure obtained by copolymerizing a monomer having the following general formula (A)

[In the above formula, A represents —O— or —NH—, R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkylene group having 1 to 18 carbon atoms, or —CH ₂ —CH (OH) — Represents CH ₂ —, R ³ and R ⁴ may be the same or different, and represent an alkyl group having 1 to 3 carbon atoms. The nitrogen atom to which R ³ and R ⁴ are bonded may be a quaternary ammonium salt. ]

  In accordance with the present invention, ink transfer, adhesion and water-resistant adhesion in high-temperature and high-humidity environments are excellent in melt thermal transfer printing, and ink transfer, adhesion and water resistance are excellent in offset printing, and in addition, antistatic A thermoplastic resin film having performance can be provided.

BEST MODE FOR CARRYING OUT THE INVENTION

  Below, the surface treatment method of the thermoplastic resin film of this invention is demonstrated in detail. The surface treatment method for a thermoplastic resin film of the present invention includes the first step, the second step, and the third step. Therefore, in the following, these steps will be described in order, and the characteristics of the thermoplastic resin film produced at the end will be referred to. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

1st process The 1st process of the surface treatment method of the thermoplastic resin film of this invention is a process of oxidizing the surface of a thermoplastic resin film.

(1) Thermoplastic resin film The thermoplastic resin film used in the first step is not particularly limited as long as it is a resin exhibiting thermoplasticity. For example, ethylene resins such as high density polyethylene and medium density polyethylene, or polyolefin resins such as propylene resin, polymethyl-1-pentene, ethylene-cyclic olefin copolymer, nylon-6, nylon-6,6, nylon Polyamide resins such as −6, 10 and nylon-6, 12, polyethylene terephthalate and copolymers thereof, thermoplastic polyester resins such as polyethylene naphthalate and aliphatic polyester, polycarbonate, atactic polystyrene, syndiotactic polystyrene, Examples thereof include thermoplastic resins such as polyphenylene sulfide. These may be used in combination of two or more.

  Among these thermoplastic resins, it is preferable to use a nonpolar polyolefin-based resin in order to further exhibit the effects of the present invention. Furthermore, among polyolefin resins, propylene resins are preferred from the viewpoints of chemical resistance and cost. Examples of such a propylene-based resin include propylene homopolymers that are isotactic or syndiotactic and polypropylene exhibiting various degrees of stereoregularity. Moreover, the copolymer which has propylene as a main component and was copolymerized with alpha-olefins, such as ethylene, butene-1, hexene-1, heptene-1, 4-methylpentene-1, can also be mentioned. 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 using a propylene homopolymer, it is preferable to blend 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 has a single-layer structure or a two-layer structure of the base material layer (i) and the surface layer (ii), the surface layer (ii) is formed on the front and back surfaces of the base material layer (i). Or a multi-layer structure in which another resin film layer is present between the base material layer (i) and the surface layer (ii). Moreover, even if it contains the inorganic fine powder and the organic filler, it may not contain.

  When the thermoplastic resin film is a polyolefin resin film having a single layer structure containing inorganic fine powder, it usually contains 40-99.5 wt% of polyolefin resin and 60-0.5 wt% of inorganic fine powder, Preferably, it contains 50 to 97% by weight of polyolefin resin and 50 to 3% by weight of inorganic fine powder. When the thermoplastic resin film has a multilayer structure and the base layer (i) and the surface layer (ii) contain inorganic fine powder, the base layer (i) is usually inorganic with 40 to 100% by weight of polyolefin resin. 60 to 0% by weight of fine powder, surface layer (ii) contains 25 to 100% by weight of polyolefin resin and 75 to 0% by weight of inorganic fine powder, preferably base layer (i) is polyolefin resin 50 to 97% by weight and 50 to 3% by weight of inorganic fine powder are contained, and the surface layer (ii) contains 30 to 97% by weight of polyolefin resin and 70 to 3% by weight of inorganic fine powder. When the inorganic fine powder contained in the single-layered thermoplastic resin film or the multilayered base material layer (i) is 60% by weight or less, the stretched resin film is unlikely to break during transverse stretching performed after longitudinal stretching. Further, when the inorganic fine powder contained in the surface layer (ii) is 75% by weight or less, the surface layer (ii) after transverse stretching has sufficient surface strength, so that paper peeling hardly occurs.

  Examples of the inorganic fine powder include calcium carbonate, calcined clay, silica, diatomaceous earth, talc, titanium oxide, barium sulfate, and alumina. The average particle size of the inorganic fine powder is preferably 0.01 to 15 μm, more preferably 0.2 to 7 μm. If the average particle size is 0.01 μm or more, troubles such as classification and aggregation can be avoided when mixing with the thermoplastic resin, and if it is 15 μm or less, colored spots are unlikely to occur.

  As the organic filler, for example, when the thermoplastic resin film is a polyolefin resin film, a polyolefin resin such as polyethylene terephthalate, polybutylene terephthalate, polycarbonate, nylon-6, nylon-6,6, or a polymer of cyclic olefin is used. Those having a melting point higher than the melting point (for example, 170 to 300 ° C.) or glass transition temperature (for example, 170 to 280 ° C.) can be preferably used.

  If necessary, the thermoplastic resin film may further contain a stabilizer, a light stabilizer, a dispersant, a lubricant and the like. Specifically, sterically hindered phenol, phosphorus, amine, etc. are 0.001 to 1% by weight as stabilizers, and sterically hindered amine, benzotriazole, benzophenone, etc. are 0.001 to 1 as light stabilizers. 1% by weight, 0.01 to 4% by weight of an inorganic fine powder dispersant, such as a silane coupling agent, higher fatty acids such as oleic acid and stearic acid, metal soap, polyacrylic acid, polymethacrylic acid or salts thereof % May be blended.

  The molding method of the thermoplastic resin film used in the first step is not particularly limited, and various conventionally known methods can be used. Specific examples include cast molding, calender molding, rolling molding, inflation molding, thermoplastic resin, and extrusion of molten resin into a sheet using a single-layer or multilayer T-die or I-die connected to a screw-type extruder. Examples thereof include removal of the solvent and oil after cast molding or calendar molding of a mixture with an organic solvent and oil, molding from a thermoplastic resin solution, and solvent removal.

  The thermoplastic resin film used in the first step may be stretched or unstretched, but it must be stretchable in the third step. . Various known methods can be used for stretching. Specific examples include longitudinal stretching using a difference in peripheral speed of rolls and transverse stretching using a tenter oven. When the thermoplastic resin film has a structure of two or more layers, all the layers may be stretched or only a part of the layers may be stretched.

  When the thermoplastic resin film is a single-layer polyolefin resin film containing inorganic fine powder, for example, a resin containing 40 to 99.5% by weight of polyolefin resin and 60 to 0.5% by weight of inorganic fine powder A resin film comprising the composition is stretched in a uniaxial direction or a biaxial direction at a temperature lower than the melting point of the polyolefin resin, preferably 3 to 60 ° C. A microporous stretched resin film having fine voids is obtained. Further, when the thermoplastic resin film has a multilayer structure, for example, the base material layer (i) containing 40 to 100% by weight of the polyolefin resin and 60 to 0% by weight of the inorganic fine powder is lower than the melting point of the polyolefin resin. Based on the surface layer (ii) comprising a resin composition which is stretched in the machine direction at a temperature, preferably 3 to 60 ° C., and then contains 25 to 100% by weight of polyolefin resin and 75 to 0% by weight of inorganic fine powder. The material layer (i) can be laminated on at least one side and used for surface treatment.

  More preferably among the above films, a polyolefin resin film containing 5 to 60% by weight of fine powders such as calcined clay, heavy or light calcium carbonate, titanium oxide and talc is uniaxially stretched, and this fine inorganic A film in which countless cracks are generated on the surface centering around the powder particles to make it translucent or opaque, a film in which the resin composition containing the fine powder is further laminated on the surface, and Japanese Patent Publication No. 1-60411, 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 as described in JP-A-61-1748 And a sheet after longitudinal stretching of sequential biaxial stretching.

  The thickness of the thermoplastic resin film used in the first step can be appropriately selected according to the stretching ratio and the thickness of the film required after stretching. In general, those having a range of 20 to 4000 μm, preferably 100 to 3000 μm are used.

(2) Oxidation treatment As the oxidation treatment performed in the first step, it is preferable to employ at least one treatment method selected from the group consisting of corona discharge treatment, flame treatment, plasma treatment, glow discharge treatment, and ozone treatment. . More preferred are corona treatment and frame treatment.

The treatment amount in the case of corona treatment is preferably 600 to 12,000 J / m ² (10 to 200 W · min / m ² ), more preferably 1,200 to 9,000 J / m ² (20 to 150 W · min / m). m ² ). If it is 600 J / m ² (10 W · min / m ² ) or more, the effect of the corona discharge treatment can be sufficiently obtained, and repellency can be effectively prevented during the subsequent application of the surface treatment agent. In addition, if it exceeds 12,000 J / m ² (200 W · min / m ² ), the effect of the treatment will reach its peak, and 12,000 J / m ² (200 W · min / m ² ) or less is sufficient.

Processing amount in the case of flame treatment is preferably 8,000~200,000J / m ^2, more preferably 20,000~100,000J / m ^2. If it is 8,000 J / m ² or more, the effect of the corona discharge treatment can be sufficiently obtained, and repellency can be effectively prevented during the subsequent application of the surface treatment agent. Further, if it exceeds 200,000 J / m ² , the effect of the treatment reaches its peak, and 200,000 J / m ² or less is sufficient.

2nd process The 2nd process of the surface treatment method of the thermoplastic resin film of this invention is the process of apply | coating the surface treating agent containing a component (A) and a component (B) to the surface of the thermoplastic resin film which oxidized. It is. The surface treatment agent used in the second step contains at least component (A) and component (B) as essential components, and may further contain component (C) and component (D). Hereinafter, each component will be described in detail.

(1) Component (A)
Component (A) comprises an olefin copolymer (a) bonded with an unsaturated carboxylic acid or an anhydride thereof, a nonionic surfactant, a nonionic water-soluble polymer, a cationic surfactant, and a cationic water solution. An aqueous dispersion dispersed in water using at least one selected from the group consisting of functional polymers as the dispersant (b), wherein the weight ratio per solid content of (a) / (b) is It is a resin aqueous dispersion having a 100/1 to 100/30 average particle size of 5 μm or less.

  It is considered that the olefin copolymer (a) to which the unsaturated carboxylic acid or its anhydride is bonded contributes to the improvement of the adhesion to the substrate and the melt thermal transferability. Further, the dispersant (b) comprising at least one selected from the group consisting of a nonionic surfactant, a nonionic water-soluble polymer, a cationic surfactant, and a cationic water-soluble polymer is thermoplastic. It is thought to improve the adhesion to the resin film.

  In the above component (A), as the olefin copolymer (a) to which the unsaturated carboxylic acid or its anhydride is bonded, ethylene- (meth) acrylic acid copolymer, (meth) acrylic acid grafted polyethylene, maleic anhydride grafted Polyethylene, maleic anhydride grafted ethylene-vinyl acetate copolymer, maleic anhydride grafted (meth) acrylic ester-ethylene copolymer, maleic anhydride grafted polypropylene, maleic anhydride grafted ethylene-propylene copolymer, maleic anhydride Examples thereof include grafted ethylene-propylene-butene copolymer, maleic anhydride grafted ethylene-butene copolymer, and maleic anhydride grafted propylene-butene copolymer.

  Among these, an ethylene- (meth) acrylic acid copolymer having a melting point or softening point of 130 ° C. or less, a maleic anhydride grafted ethylene-vinyl acetate copolymer, a maleic anhydride grafted (meth) acrylic acid ester-ethylene copolymer. Polymers, maleic anhydride grafted ethylene-propylene-butene copolymers, maleic anhydride grafted ethylene-butene copolymers, and maleic anhydride grafted propylene-butene copolymers are particularly preferred from the viewpoint of ink acceptability.

The dispersant (b) for dispersing the olefin copolymer to which the unsaturated carboxylic acid or its anhydride is bonded in water includes a nonionic surfactant, a nonionic water-soluble polymer, a cationic surfactant, And at least one selected from the group consisting of cationic water-soluble polymers. Even if these are used as a component for dispersing the olefin copolymer (a), they are preferable because they do not hinder printability due to the influence of the dispersant itself.
Anionic surfactants such as polysulfonic acid sodium salts that are usually widely used as dispersants are not preferred because sufficient ink adhesion cannot be obtained and offset printability tends to be reduced. Also, an aqueous dispersion in which the carboxylic acid is converted to an ammonium salt or an alkylamine salt in the olefin copolymer to which the unsaturated carboxylic acid or its anhydride is bonded so as to have dispersibility in water is not suitable for offset printing. It is sufficient and not preferable. These are presumed to be because the polarity of the dispersant is too high.

Examples of the nonionic surfactant that can be used as the dispersant (b) include polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene oxypropylene block polymer, polyethylene glycol fatty acid ester, polyoxyethylene sorbitan fatty acid. An ester etc. can be illustrated.
Examples of the nonionic water-soluble polymer include fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, modified products thereof, and hydroxyethyl cellulose.
Examples of the cationic surfactant include stearylamine hydrochloride, lauryltrimethylammonium chloride, trimethyloctadecylammonium chloride and the like.
Furthermore, examples of the cationic water-soluble polymer include polymers having a quaternary ammonium salt structure or a phosphonium salt structure, nitrogen-containing (meth) acrylic polymers, and (meth) acrylic polymers having nitrogen having a quaternary ammonium salt structure. be able to.

  Among these, cations such as nitrogen-containing (meth) acrylic polymers or (meth) acrylic polymers having nitrogen of a quaternary ammonium salt structure from the viewpoints of adhesion to thermoplastic resin films and suitability for offset printing. It is particularly preferable to use a water-soluble polymer.

  In order to disperse the olefin copolymer (a) to which the unsaturated carboxylic acid or its anhydride is bound in water using the dispersant (b), the ratio of the weight per solid content of (a) / (b) Needs to be 100/1 to 100/30. If the amount of the dispersant used is less than this range, the olefin copolymer to which the unsaturated carboxylic acid or its anhydride is bonded cannot be dispersed in water. Conversely, when the amount of the dispersant used increases, the influence of the excess dispersant becomes noticeable, impairing the adhesion to the thermoplastic resin film support, resulting in insufficient ink adhesion and lowering offset printability. It tends to make it. It also has an adverse effect on the improvement effect of poor adhesion of melt thermal transfer ink under high temperature and high humidity. The ratio of the weight per solid content of (a) / (b) is more preferably from 100/1 to 100/20, further preferably from 100/5 to 100/20, and from 100/5 to 100/20. 15 is particularly preferred.

  The average particle diameter of the resin particles obtained by dispersing the component (A) in the present invention in an aqueous solvent is required to be 5 μm or less. When it exceeds 5 μm, not only the stationary stability of the aqueous dispersion is deteriorated, but also the adhesiveness of the thermoplastic resin film to the support is deteriorated. The average particle size of the resin particles composed of the component (A) of the present invention is 5 μm or less, more preferably 3 μm or less, further preferably 2 μm or less, and particularly preferably 1 μm or less.

  In order to disperse the olefin copolymer (a) to which the unsaturated carboxylic acid or its anhydride is bonded using the dispersant (b) in water, for example, the olefin copolymer is added to an aromatic hydrocarbon solvent. In which the dispersant (b) is mixed and stirred, followed by phase transformation while adding water, and then the aromatic hydrocarbon solvent is distilled off to obtain an aqueous dispersion. As disclosed in JP-A-29447, the olefin copolymer is supplied to a hopper of a twin-screw extruder, and an aqueous solution of the dispersant (b) is added to the melted state by heating and kneading. Examples thereof include a method of subsequently adding water to obtain a dispersion. Among these, when the dispersing agent (b) is a cationic water-soluble polymer such as a nitrogen-containing (meth) acrylic polymer or a (meth) acrylic polymer having nitrogen having a quaternary ammonium salt structure, From the viewpoint of the average particle diameter of the resin particles in the obtained aqueous dispersion, it is preferable to use a twin screw extruder. A method using a twin screw extruder is preferred because the olefin copolymer (a) can form an aqueous dispersion even if the olefin copolymer (a) has a lower polarity and a higher molecular weight, and can further improve the adhesion between the surface treatment agent and the support film. .

  The melting point of the solid component (A) thus obtained is usually 60 to 150 ° C, preferably 70 to 140 ° C, more preferably 80 to 130 ° C, and further preferably 90 to 120 ° C.

(2) Component (B)
The component (B) is a nitrogen-containing acrylic polymer having a structure obtained by copolymerizing a monomer represented by the following general formula (A). By using the component (B), antistatic properties can be imparted to the thermoplastic resin film after the application of the surface treatment agent.
When only the olefin copolymer dispersion of component (A) is applied without using component (B), antistatic performance cannot be obtained. For example, when printing paper is supplied in the form of sheets (sheets) as in offset printing, the ease of charging the printing paper causes problems such as paper supply and discharge problems, and thus antistatic properties are required. . In addition, even if the printing paper is printed in roll form, such as letterpress printing, gravure printing, flexographic printing, etc., the material that has been cut or punched after printing has a tendency to be poorly aligned due to charging or to be blocked. For this reason, antistatic properties are usually required for printed materials. For this reason, in this invention, a component (B) is used with a component (A).

In the above formula, A represents —O— or —NH—, R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkylene group having 1 to 18 carbon atoms, or —CH ₂ —CH (OH) —CH. _2- represents, R ³ and R ⁴ may be the same or different, and represent an alkyl group having 1 to 3 carbon atoms. The nitrogen atom to which R ³ and R ⁴ are bonded may be a quaternary ammonium salt.

The number of carbon atoms of the alkylene group R ² is preferably 1 to 10, more preferably 1 to 6, more preferably from 1 to 3. In addition, the alkylene group may be linear or branched. Preferred as R ³ and R ⁴ is a methyl group.

In the nitrogen-containing acrylic polymer obtained by copolymerizing the monomer represented by the general formula (A), a group derived from —NR ³ R ⁴ of the general formula (A) is present. This group is preferably a quaternary ammonium salt because the antistatic property is improved. Examples of the quaternizing agent include cationizing agents such as alkyl halides, dimethyl sulfate, and monochloroacetate.

  The component (B) needs to be water-soluble or water-dispersible, but it is not desirable to be excessively water-soluble. Therefore, the nitrogen-containing acrylic polymer is desirably a copolymer with a hydrophobic monomer. Examples of the hydrophobic monomer include styrene or its nucleus or side chain substituted product, acrylic or methacrylic acid ester, and vinyl halide.

Particularly preferred as component (B) is a copolymer of the following three monomers.
Nitrogen-containing monomer represented by general formula (A) 20 to 40% by weight
60-80% by weight of a monomer represented by the following general formula (B)
0 to 20% by weight of other hydrophobic vinyl monomers

The most suitable component (B) is a quaternary ammonium salt copolymer obtained by copolymerizing the following three monomers (Japanese Patent Laid-Open No. 6-25447).
30 to 70% by weight of a monomer represented by the following general formula (B)
Monomers represented by the following general formula (C): 30 to 70% by weight
Other hydrophobic vinyl monomers 0-40% by weight

［式中、Ｒ⁵は水素原子またはメチル基を表し、Ｒ⁶は炭素数が１〜２２のアルキル基、炭素数が７〜２２のアラルキル基、若しくは炭素数５〜２２のシクロアルキル基を表す。］
一般式（Ｂ）のＲ⁶のアルキル基の炭素数は好ましくは１〜１８であり、より好ましくは１〜８であり、さらに好ましくは１〜５である。アルキル基は直鎖であっても分枝状であってもよい。Ｒ⁶のアラルキル基の炭素数は好ましくは７〜１８であり、より好ましくは７〜１４であり、さらに好ましくは７〜１０である。Ｒ⁶のシクロアルキル基の炭素数は好ましくは５〜１４であり、より好ましくは５〜１０であり、さらに好ましくは５〜６である。

[Wherein, R ⁵ represents a hydrogen atom or a methyl group, and R ⁶ 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. . ]
The carbon number of the alkyl group represented by R ^{6 in} the general formula (B) is preferably 1 to 18, more preferably 1 to 8, and further preferably 1 to 5. The alkyl group may be linear or branched. The carbon number of the aralkyl group of R ⁶ is preferably 7-18, more preferably 7-14, and still more preferably 7-10. The carbon number of the cycloalkyl group of R ⁶ is preferably 5 to 14, more preferably 5 to 10, and still more preferably 5 to 6.

  Examples of the hydrophobic monomer unit represented by the general formula (B) include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, tertiary butyl (meth) acrylate, cyclohexyl ( Mention may be made of alkyl (meth) acrylates such as (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, stearyl (meth) acrylate and the like.

［式中、Ａは−Ｏ−または−ＮＨ−を表し、Ｒ⁷は水素原子またはメチル基を表し、Ｒ⁸は炭素数が２〜４のアルキレン基または−ＣＨ₂−ＣＨ（ＯＨ）−ＣＨ₂−を表し、Ｒ⁹、Ｒ¹⁰、Ｒ¹¹およびＲ¹²は同一であっても異なっていてもよく、それぞれ炭素数が１〜３のアルキル基を表し、Ｒ¹³は炭素数が１〜１０アルキル基または炭素数が７〜１０のアラルキル基を表し、Ｘは塩素原子、臭素原子または沃素原子を表す。］
一般式（Ｃ）のＲ¹³のアルキル基の炭素数は好ましくは１〜８であり、より好ましくは１〜５であり、さらに好ましくは１〜３である。アルキル基は直鎖であっても分枝状であってもよい。Ｘとして好ましいのは塩素原子である。

[Wherein, A represents —O— or —NH—, R ⁷ represents a hydrogen atom or a methyl group, R ⁸ represents an alkylene group having 2 to 4 carbon atoms, or —CH ₂ —CH (OH) —CH _2- represents, R ⁹ , R ¹⁰ , R ¹¹ and R ¹² may be the same or different, each represents an alkyl group having 1 to 3 carbon atoms, and R ¹³ represents 1 to 10 carbon atoms. An alkyl group or an aralkyl group having 7 to 10 carbon atoms is represented, and X represents a chlorine atom, a bromine atom or an iodine atom. ]
Preferably carbon number of the alkyl group of R < ¹³ > of General formula (C) is 1-8, More preferably, it is 1-5, More preferably, it is 1-3. The alkyl group may be linear or branched. X is preferably a chlorine atom.

  Examples of the monomer represented by the general formula (C) include tertiary amine-containing monomers such as dimethylaminoethyl acrylate, diethylaminoethyl acrylate, and methacrylate equivalents thereof, dimethylaminopropylacrylamide, and methacrylate equivalents thereof. Can be obtained by modification with a cationizing agent represented by the following general formula (D) such as 3-chloro-2-hydroxypropyltrimethylammonium chloride.

［式中、Ｒ¹⁴およびＲ¹⁵は同一であっても異なっていてもよく、それぞれ炭素数が１〜３のアルキル基を表し、Ｒ¹⁶は炭素数が１〜１０アルキル基または炭素数が７〜１０のアラルキル基を表し、ｎは１〜３の整数で、Ｘは塩素原子、臭素原子または沃素原子を表す。］
一般式（Ｄ）のＲ¹⁶のアルキル基の炭素数は好ましくは１〜８であり、より好ましくは１〜５であり、さらに好ましくは１〜３である。アルキル基は直鎖であっても分枝状であってもよい。Ｘとして好ましいのは塩素原子である。

[Wherein R ¹⁴ and R ¹⁵ may be the same or different and each represents an alkyl group having 1 to 3 carbon atoms; R ¹⁶ 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. ]
Carbon number of the alkyl group of R ^{16 in} the general formula (D) is preferably 1 to 8, more preferably 1 to 5, and further preferably 1 to 3. The alkyl group may be linear or branched. X is preferably a chlorine atom.

  The polymer of the component (B) having a quaternary ammonium group can be obtained by copolymerizing a quaternary ammonium monomer such as the monomer represented by the general formula (C). ), A monomer containing a tertiary amine can be copolymerized to form a polymer, and then quaternized with a cationizing agent.

  In addition to the monomers represented by the general formulas (A), (B), and (C), a copolymerizable monomer can be used as necessary. For example, hydrophobic monomers such as styrene, vinyl toluene and vinyl acetate, and hydrophilic monomers such as vinyl pyrrolidone and (meth) acrylamide can be used.

  Examples of the polymerization method for obtaining the nitrogen-containing acrylic polymer of component (B) include known polymerization methods such as bulk polymerization, solution polymerization, and emulsion polymerization using a radical initiator. Among these, the preferred polymerization method is solution polymerization, and the polymerization 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. The solvent may be used by mixing them. As the polymerization initiator, peroxides such as benzoyl peroxide and lauroyl peroxide, and azo compounds such as azobisisobutyronitrile and azobisvaleronitrile are preferably used. The monomer concentration is usually 10 to 60% by weight, and the concentration of the polymerization initiator is usually 0.1 to 10% by weight with respect to the monomer.

The molecular weight of the quaternary ammonium salt type copolymer can be set to any level depending on the polymerization conditions such as the polymerization temperature, the type and amount of the polymerization initiator, the amount of solvent used, and the chain transfer agent. In general, the molecular weight of the obtained polymer is 1,000 to 1,000,000, but the range of 1,000 to 500,000 is particularly preferable.
Even if the nitrogen-containing acrylic polymer of component (B) thus obtained is applied alone on a thermoplastic resin film and dried to form a film, sufficient adhesion to the thermoplastic resin film cannot be obtained. It is normal. And since hydrophilicity is good, water resistance is hardly obtained. However, in the present invention, the component (A) exhibits sufficient adhesion to the film as the support, and at the same time, the component (B) is thermoplastic due to the entanglement effect between the polymers with the component (B). The effect of fixing on the resin film is also shown. As a result, according to the present invention, a thermoplastic resin film having not only adhesiveness but also stable antistatic properties and water resistance can be obtained.

(3) Component (C)
Component (C) is a polyimine polymer or an ethyleneimine adduct of polyamine polyamide. By adding the component (C) to the surface treatment agent, it is possible to further improve the water-resistant adhesion with a printing ink that tends to decrease due to the addition of an antistatic agent or the like that is a hydrophilic component.

  Component (C) includes polyethyleneimine, poly (ethyleneimine-urea) and polyamine polyamide ethyleneimine adducts, or alkyl-modified, cycloalkyl-modified, aryl-modified, allyl-modified, aralkyl-modified, Examples include alchiral modified products, benzyl modified products, cyclopentyl modified products, and aliphatic cyclic hydrocarbon modified products, or hydroxides thereof. These may be used alone or in combination of several kinds. Among these, it is preferable to use a polyimine polymer represented by the following general formula (E). Here, any degree of polymerization of polyethyleneimine is used, but it is preferably 20 to 3,000.

In the above formula, R ¹⁷ and R ¹⁸ are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 10 carbon atoms, an alkyl group having an alicyclic structure, or an aryl group; ¹⁹ is a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an allyl group, an alkyl group having an alicyclic structure, an aryl group, or a hydroxide thereof, and m is an integer in the range of 2 to 6. Yes, n is an integer in the range of 20-3000. The n structural units may be the same as or different from each other.
Carbon number of the alkyl group of R <^17> and R < ¹⁸ > of general formula (E) becomes like this. Preferably it is 1-8, More preferably, it is 1-4, More preferably, it is 1-2. Carbon number of the alkyl group of R ¹⁹ is preferably 1 to 18, more preferably 1 to 10, and further preferably 1 to 4. These alkyl groups may be linear or branched. The number of carbon atoms in the aryl group of R ¹⁷ , R ¹⁸ and R ¹⁹ is preferably 4 to 10, more preferably 5 to 10, and further preferably 6 to 8. The carbon number of the alkyl group having an alicyclic structure of R ¹⁷ , R ¹⁸ and R ¹⁹ is preferably 5 to 14, more preferably 5 to 10, and further preferably 6 to 8. The preferred range for m is 2-3. Moreover, the preferable range of n is 100-10000, and a more preferable range is 500-5000.

(4) Component (D)
Component (D) is one or more crosslinking agents selected from the group of water-soluble resins consisting of epoxy resins, isocyanate resins, formalin resins, and oxazoline resins. When the component (D) is added to the surface treatment agent used in the present invention, the water-resistant adhesion with the printing ink can be further improved. As component (D), bisphenol A-epichlorohydrin resin, polyamine polyamide epichlorohydrin resin, aliphatic epoxy resin, epoxy novolac resin, cycloaliphatic epoxy resin, brominated epoxy resin are preferred, and most preferred is polyamine polyamide epichlorohydrin. Examples thereof include adducts, monofunctional to polyfunctional glycidyl ethers, and glycidyl esters.

(5) Preparation and application of surface treatment agent The surface treatment agent used in the present invention mixes component (A), component (B), and component (C), component (D), and other components as necessary. Can be prepared. The mixing method is not particularly limited. In the surface treatment agent used in the present invention, it is preferable to mix the component (B) to the component (D) in the following ratio with respect to 100 parts by weight of the component (A).
Component (B) preferably 1 to 25 parts by weight, more preferably 2 to 15 parts by weight Component (C) preferably 0 to 25 parts by weight, more preferably 2 to 15 parts by weight Component (D) preferably 0 to 25 parts by weight Parts, more preferably 2 to 15 parts by weight

  To the surface treatment agent used in the present invention, auxiliary agents such as an antifoaming agent, a wetting agent, and an antiblocking agent may be added as necessary as long as the melt heat transfer suitability and the offset printing suitability are not impaired.

  The surface treatment agent used in the present invention has a film elongation of preferably 100% or more, more preferably 120 to 500%, and further preferably 130 to 400%. If the film elongation is 100% or more, the film formed after applying the surface treatment agent can sufficiently follow the stretching of the thermoplastic resin film, so that the film is cracked and the ink adhesion of the film is greatly reduced. You can avoid the situation.

  Each component of the surface modifier is used as it is or after being diluted and dissolved in a hydrophilic solvent such as water, methyl alcohol, ethyl alcohol, or isopropyl alcohol. Among these, it is preferable to use in the form of an aqueous solution. The solution concentration is usually 0.05 to 60% by weight, preferably about 0.1 to 40% by weight. If it is 0.05 mass% or more, the drying process of water | moisture content and the time of drying can be set to a moderate length. Moreover, if it is 60 weight% or less, generation | occurrence | production of a coating spot can be suppressed more.

  As a coating method, 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, or the like can be appropriately employed. Further, if necessary, smoothing can be performed, or excess water and hydrophilic solvent can be removed through a drying step.

The coating amount is usually 0.005~10g / m ² as solid content after drying is preferably 0.01 to 1 g / m ^2, more preferably a 0.01~0.6g / m ^2. If it is 0.005 g / m ² or more, the effect of improvement is sufficiently exerted, and if it exceeds 10 g / m ² , the effect is saturated.

3rd process 3rd process is a process of extending | stretching the thermoplastic resin film which apply | coated the surface treating agent. The third step may be performed after drying the surface treatment agent applied in the second step, or may be performed simultaneously with the drying. Preference is given to carrying out simultaneously with drying. By doing so, it is predicted that the substrate and the surface treatment agent are firmly fixed, and as a result, the water resistance of the printed matter is considered to increase.

  The drying temperature of the surface treatment agent is preferably 20 ° C. or more higher than the melting point of the component (A), more preferably 30 to 100 ° C., and even more preferably 50 to 80 ° C. If it is 20 degreeC or more, since a surface treating agent fully fuse | melts on a film and the adhesiveness of a thermoplastic resin film and a surface modifier is hard to fall, it is preferable.

For stretching, various conventionally known methods can be used. In the case of an amorphous resin, a known value suitable for each thermoplastic resin having a temperature higher than the glass transition temperature of the thermoplastic resin to be used, and in the case of a crystalline resin, higher than the glass transition temperature of the amorphous portion to the melting point of the crystalline portion. In the temperature range. Specific stretching methods include longitudinal stretching using a difference in peripheral speed between rolls, lateral stretching using a tenter oven, rolling, and simultaneous biaxial stretching using a combination of a tenter oven and a linear motor.
The stretching direction can be appropriately determined in consideration of the purpose of use and usage of the thermoplastic resin film. For example, the first step and the second step of the present invention are performed using a multilayer resin film in which a surface layer (ii) made of a thermoplastic resin is laminated on at least one side of a base material layer (i) made of a longitudinally stretched thermoplastic resin. When implemented, the thermoplastic resin film can be laterally stretched in the third step. By adopting such an embodiment, there is an advantage that a film having both film strength and flexibility can be manufactured. Further, an unstretched thermoplastic resin film may be longitudinally uniaxially stretched in the third step.

  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.), 110 to 164 ° C., high density polyethylene (melting point 121 to 134 ° C. ) Is preferably 110 to 120 ° C. and polyethylene terephthalate (melting point 246 to 252 ° C.) is preferably 104 to 115 ° C., and is appropriately selected depending on the stretching process and conditions.

The draw ratio is not particularly limited, and is appropriately selected depending on the purpose and the characteristics of the thermoplastic resin used. For example, when polypropylene or a copolymer thereof is used as the thermoplastic resin and stretched in one direction, it is usually about 1.2 to 12 times, preferably 2 to 10 times. The area magnification is usually 1.5 to 60 times, preferably 10 to 50 times. When stretching in one direction using other thermoplastic resins, it is usually 1.2 to 10 times, preferably 2 to 5 times, and when biaxially stretching, it is usually 1.5 to 20 times in area magnification. Preferably it is 4 to 12 times. Furthermore, heat treatment at a high temperature is performed as necessary. The stretching speed is preferably 20 to 350 m / min.
The elongation of the film of the surface treatment agent in the present invention is the elongation when the surface treatment agent provided on the thermoplastic resin film is simultaneously stretched along with the stretching of the film, and is usually a thermoplastic resin. It is equal to the film draw ratio in terms of%. The elongation of the film of the surface treatment agent in the present invention is usually 100% or more, and preferably greater than 100%. When polypropylene or a copolymer thereof is used as the thermoplastic resin and stretched in one direction, it is usually about 120 to 1200%, preferably 200 to 1000%, and when biaxially stretched, it is usually 150 to 6000 in area magnification. %, Preferably 1000 to 5000%. When stretching in one direction using another thermoplastic resin, it is usually 120 to 1000%, preferably 200 to 500%. When biaxially stretching, the area magnification is usually 150 to 2000%, preferably 400 to 1200%.

When the thermoplastic resin film contains an inorganic fine powder or an organic filler, fine cracks are produced on the film surface, and fine voids are produced inside the film.
The thickness of the stretched thermoplastic resin film is usually 20 to 500 μm, preferably 35 to 300 μm.
The surface specific resistance value of the stretched thermoplastic resin film is preferably 1 × 10 ¹² Ω / □ or less from the viewpoint of antistatic performance. When it exceeds 1 × 10 ¹² Ω / □, the substrate is charged during offset printing, and the paper supply / discharge performance is greatly reduced.

The stretched thermoplastic resin film preferably has a porosity of 10 to 60% represented by the following formula, more preferably 10 to 50%, and even more preferably 20 to 40%. Density from 0.650 to 1. Is preferably 20 g / cm ^3, more preferably 0.65~1.10g / cm ^3, further to be 0.70~0.95g / cm ³ preferable. The opacity is preferably 75% or more, more preferably 80% or more, and further preferably 90% or more. The Beck smoothness is preferably 50 to 25,000 seconds, more preferably 50 to 15,000 seconds, and further preferably 100 to 5,000 seconds.

  In the present invention, the surface oxidation treatment in the first step may be performed again on the stretched film for the purpose of preventing the film from being charged. Moreover, you may add the process of laminating | stacking the layer which has a specific function on the surface as needed, or cut | disconnecting to a specific shape.

  The thermoplastic resin film subjected to the surface treatment according to the present invention has the characteristics that it exhibits excellent ink transferability, adhesion and water-resistant adhesion under high temperature and high humidity environments when performing melt thermal transfer printing. is doing. In addition, when offset printing is performed, the ink has excellent ink transferability, adhesion, and water resistance. Furthermore, the thermoplastic resin film subjected to the surface treatment according to the present invention has a feature that it has excellent antistatic performance. As described above, the usefulness of the present invention is extremely high in that it is possible to produce a thermoplastic resin film having good aptitude for offset printing and aptitude for melting thermal transfer printer by performing a simple surface treatment.

  The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

<Production example>
The manufacturing method of the component of the surface treating agent used by the Example and comparative example which are mentioned later is described below.

Ingredient (A)
Four equipped with 62.9 parts by weight of N, N-dimethylaminoethyl methacrylate, 71 parts by weight of butyl methacrylate, 25.4 parts by weight of lauryl methacrylate and 200 parts by weight of isopropyl alcohol, equipped with a stirrer, reflux condenser, thermometer and dropping funnel. After charging in the neck flask and replacing with nitrogen gas, 0.9 part by weight of 2,2′-azobisisobutyronitrile was added as a polymerization initiator, and a polymerization reaction was carried out at 80 ° C. for 4 hours. Next, after neutralizing with 24 parts by weight of acetic acid, water was added while distilling off isopropyl alcohol, and finally an aqueous solution (b) of a viscous cationic dispersant having a solid content of 35% was obtained.

  An ethylene-methacrylic acid copolymer (methacrylic acid content 10%, MFR 35 g / 10 min) (a) (a) at a rate of 100 parts by weight / hour in the same direction meshing type twin screw extruder (product name: PCM45φ, manufactured by Ikegai Co., Ltd.) Continuously fed. Further, from the first inlet of the extruder, the aqueous solution (b) of the dispersant is continuously added at a rate of 22.9 parts by weight / hour (the solid content as the dispersant is 8 parts by weight / hour). Supplied. Further, while continuously supplying water at a rate of 70 parts by weight / hour from the second inlet of the extruder, it was continuously extruded at a heating temperature (cylinder temperature) of 130 ° C. to obtain a milky white aqueous resin dispersion. It was. The resin aqueous dispersion was filtered through a 250 mesh stainless steel wire mesh, and water was added so that the solid content was 45%.

  It was 0.74 micrometer when the average particle diameter of this resin aqueous dispersion was measured with the laser type particle size distribution measuring apparatus (the Shimadzu make, SALD-2000). Further, after evaporating and solidifying water in the obtained aqueous dispersion, the melting point of the obtained solid was measured with a differential operation calorimeter (DSC-6200, manufactured by Seiko Instruments Inc.) and found to be 94 ° C. .

Ingredient (B-1)
A four-necked flask equipped with a reflux condenser, a thermometer, a glass tube for nitrogen substitution, and a stirrer, 35 parts by weight of dimethylaminoethyl methacrylate, 20 parts by weight of ethyl methacrylate, 20 parts by weight of cyclohexyl methacrylate, stearyl methacrylate 25 parts by weight, 150 parts by weight of ethyl alcohol and 1 part by weight of azobisisobutyronitrile were added, and a polymerization reaction was performed at a temperature of 80 ° C. for 6 hours under a nitrogen stream. Next, ethyl alcohol was distilled off while dropping water into the system to obtain a nitrogen-containing acrylic polymer having a final solid content of 30%.

Ingredient (B-2)
A four-necked flask equipped with a reflux condenser, a thermometer, a glass tube for nitrogen substitution, and a stirrer, 35 parts by weight of dimethylaminoethyl methacrylate, 20 parts by weight of ethyl methacrylate, 20 parts by weight of cyclohexyl methacrylate, stearyl methacrylate 25 parts by weight, 150 parts by weight of ethyl alcohol and 1 part by weight of azobisisobutyronitrile were added, and a polymerization reaction was performed at a temperature of 80 ° C. for 6 hours under a nitrogen stream. Furthermore, after adding 70 parts by weight of a 60% by weight ethyl alcohol solution of 3-chloro-2-hydroxypropylammonium chloride and further reacting at a temperature of 80 ° C. for 15 hours, the ethyl alcohol was distilled off while dropping water, A quaternary ammonium salt type acrylic polymer having a final solid content of 30% was obtained. This copolymer is an acrylic acid alkyl ester polymer containing a group represented by the following formula (F) in the molecular chain.

Ingredient (C-1)
In a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet, a 25% by weight aqueous solution of polyethyleneimine (manufactured by Nippon Shokubai Co., Ltd., trade name Epomin P-1000, degree of polymerization 1600) 100 Part by weight, 10 parts by weight of glycidol and 10 parts by weight of propylene glycol monomethyl ether were added and stirred under a nitrogen stream, and a denaturation reaction was performed at a temperature of 80 ° C. for 16 hours to obtain a glycidol-modified polyethyleneimine aqueous solution. This was dried and then subjected to infrared spectroscopic analysis, ¹ H-nuclear magnetic resonance spectroscopic analysis ( ¹ H-NMR), and ¹³ C-nuclear magnetic resonance spectroscopic analysis ( ¹³ C-NMR). It was confirmed that the product had a structure in which a group was added to nitrogen of polyethyleneimine, and that 23% of nitrogen of polyethyleneimine was a product reacted with glycidol.

Ingredient (C-2)
In a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet, a 25% by weight aqueous solution of polyethyleneimine (manufactured by Nippon Shokubai Co., Ltd., trade name Epomin P-1000, degree of polymerization 1600) 100 Part by weight, 10 parts by weight of n-butyl chloride and 10 parts by weight of propylene glycol monomethyl ether were added and stirred under a nitrogen stream, and a modification reaction was carried out at a temperature of 80 ° C. for 20 hours to obtain a 20% by weight butyl-modified polyethyleneimine aqueous solution. Obtained.

Ingredient (D-1)
Epiamine hydrin adduct of polyamine polyamide (manufactured by Nippon PMC Co., Ltd., trade name WS-570, solid content 12.5% by weight)

In the following Examples and Comparative Examples, the above-mentioned components were mixed so as to have the composition described in Table 1, and a surface treatment agent was prepared and used. In addition, the film elongation of each surface treating agent described in Table 1 is measured by the following procedure.
The surface treatment agent was poured into a Teflon pad (Teflon: registered trademark) so that the film thickness after drying was 1.5 mm and dried at room temperature for 7 days. After punching the film into a dumbbell No. 3, the film elongation was measured at a tensile speed of 500 m / min with an autograph (manufactured by Shimadzu Corporation, trade name AGS-5kND) by a measuring method in accordance with the procedure of JIS K-6251. It was measured with 300% as the upper limit. The film elongation is calculated by the following formula.
Film elongation (%) = (L1-L0) ÷ L0 × 100
L1: Distance between marked lines when cutting (mm)
L0: Distance between marked lines before cutting (mm)

<Example 1>
(1) Production of resin sheet A composition (c ′) comprising 85% by weight of polypropylene having a melt flow rate (MFR) of 0.8 g / 10 min and 15% by weight of heavy calcium carbonate having an average particle diameter of 1.5 μm. The mixture was kneaded with an extruder set at 240 ° C., then extruded into a sheet, and cooled with a cooling device to obtain an unstretched sheet. In addition, in the composition extruded into the sheet form and the composition used for the following extrusion and lamination, 3-methyl-2,6-di- with respect to 100 parts by weight of the total amount of polypropylene and calcium carbonate to be used. t-Butylphenol 0.05 parts by weight, phenolic stabilizer Irganox 1010 (product name, manufactured by Ciba-Gaykey) 0.05 parts by weight, phosphorus stabilizer Weston 618 (manufactured by Borg Warner Co., Ltd., product) Name) 0.05 part by weight was blended. This sheet was heated to a temperature of 140 ° C. and stretched 5 times in the machine direction.

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

(2) Oxidation treatment A corona discharge treatment was performed on one surface of the five-layer laminate (P1) using a corona discharge treatment machine (trade name HFS400F, manufactured by Kasuga Electric Co., Ltd.). In the corona discharge treatment, a silicone-coated roll was used as the treater roll, the gap between the aluminum 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 .

(3) Application of surface treatment agent Next, a surface treatment agent having the composition shown in Table 1 is applied to the surface subjected to the corona discharge treatment, and the dry coating amount after stretching is about 0.15 g / m ^2. It was applied by a bar coater so as to be.

(4) Stretching Before the applied surface treatment agent is completely dried, it is heated to 155 ° C. in a tenter oven, and then stretched 8.5 times in the transverse direction to form a 5-layer laminated film having a thickness of 110 μm ( The thickness of each layer was 6 μm / 23 μm / 52 μm / 23 μm / 6 μm). The porosity of this film was 25%. In the present invention, the drying of the surface treatment agent is completed simultaneously with the stretching.

<Example 2>
A film was produced in the same manner as in Example 1 except that the component (B) of the surface treatment agent was changed to (B-2) and the compounding ratio was changed as shown in Table 1.

< Reference Example 1 >
A film was produced in the same manner as in Example 2 except that component (C) (C-1) was added to the surface treatment agent and the compounding ratio was changed as shown in Table 1.

< Reference Example 2 >
A film was produced in the same manner as in Reference Example 1 except that the component (C) of the surface treatment agent was changed to (C-2).

< Reference Example 3 >
The following (D-1) which is a component (D) was added to the surface treatment agent, and a film was produced by the same operation as in Reference Example 2 except that the compounding ratio was changed as shown in Table 1.

< Reference Example 4 >
Instead of the corona treatment used to perform the oxidation treatment, a fringe F3000 direct flame plasma treatment machine manufactured by FLYNN BURNER was used, propane was used as the combustion gas, a line speed of 40 m / min, and an applied energy of 37 A film was produced in the same manner as in Reference Example 3 except that the frame treatment was performed at 700 J / m ² .

<Example 3 >
When preparing the component (A) of the surface treatment agent, the dispersant (b) is a commercially available nonionic surfactant (water-soluble polymer) (from Kuraray Co., Ltd. A milky white aqueous resin dispersion was obtained by the same operation as in the above production example, except that it was changed to an aqueous solution of the product name POVAL PVA117). The resin aqueous dispersion was filtered through a 100-mesh stainless steel wire mesh, and water was added so that the solid content was 45%.
The average particle size of this aqueous resin dispersion was measured with a laser particle size distribution analyzer and found to be 3 μm. Further, after evaporating and solidifying water in the obtained aqueous dispersion, the melting point of the obtained solid was measured with a differential operation calorimeter, and found to be 93 ° C.
A film was produced in the same manner as in Example 1 except that the component (A) of the surface treatment agent was changed to the above.

<Example 4 >
When preparing the component (A) of the surface treating agent, the aqueous solution (b) of the dispersing agent is continuously supplied at a rate of 71.5 parts by weight / hour (the solid content as the dispersing agent is 25 parts by weight / hour). A milky white resin aqueous dispersion was obtained by the same operation as in the production example, except that the above. The resin aqueous dispersion was filtered through a 250 mesh stainless steel wire mesh, and water was added so that the solid content was 45%.
It was 0.7 micrometer when the average particle diameter of this resin aqueous dispersion was measured with the laser type particle size distribution analyzer. Moreover, after evaporating and solidifying the water in the obtained aqueous dispersion, the melting point of the obtained solid was measured with a differential operation calorimeter and found to be 94 ° C.
A film was produced in the same manner as in Example 1 except that the component (A) of the surface treatment agent was changed to the above.

<Comparative Example 1>
A film was prepared in the same manner as in Example 1 except that the surface treatment agent having the composition shown in Table 1 was applied without performing corona discharge treatment before stretching. However, since evaluation occurred when applying the surface treatment agent and a film having a uniform surface treatment was not obtained, the subsequent evaluation was stopped.

<Comparative example 2>
A film was produced in the same manner as in Example 1 except that the surface treatment agent was not applied.

<Comparative Example 3>
When preparing the component (A) of the surface treating agent, a sodium polysulfonate emulsifier is used as the dispersing agent (b), and the polymer (a) is dispersed in an autoclave (200 ° C., 5 atm) to give a milky white resin aqueous solution. A dispersion was obtained. The resin aqueous dispersion was filtered through a 250 mesh stainless steel wire mesh, and water was added so that the solid content was 45%.
The average particle size of the aqueous resin dispersion was measured with a laser particle size distribution measuring device and found to be 1 μm. Further, after evaporating and solidifying water in the obtained aqueous dispersion, the melting point of the obtained solid was measured with a differential operation calorimeter, and found to be 93 ° C.
A film was produced in the same manner as in Example 1 except that the component (A) of the surface treatment agent was changed to the above.

<Comparative example 4>
When preparing the component (A) of the surface treatment agent, the aqueous solution (b) of the dispersant is continuously added at a rate of 1.4 parts by weight / hour (the solid content as the dispersant is 0.5 parts by weight / hour). The same operation as in the above production example was performed except that the product was supplied to. However, the olefin copolymer could not be uniformly dispersed in water, and a dispersion could not be prepared under the same conditions.

<Comparative Example 5>
When preparing the component (A) of the surface treatment agent, the aqueous solution (b) of the dispersant was continuously supplied at a rate of 100 parts by weight / hour (the solid content as the dispersant was 35 parts by weight / hour). Except for the above, a milky white aqueous resin dispersion was obtained by the same operation as in the above production example. The resin aqueous dispersion was filtered through a 250 mesh stainless steel wire mesh, and water was added so that the solid content was 45%.
It was 0.7 micrometer when the average particle diameter of this resin aqueous dispersion was measured with the laser type particle size distribution analyzer. Moreover, after evaporating and solidifying the water in the obtained aqueous dispersion, the melting point of the obtained solid was measured with a differential operation calorimeter and found to be 94 ° C.
A film was produced in the same manner as in Example 1 except that the component (A) of the surface treatment agent was changed to the above.

<Comparative Example 6>
When preparing the component (A) of the surface treatment agent, the ethylene-methacrylic acid copolymer (a), the aqueous solution (b) of the dispersant, and the amount of water supplied to the twin-screw extruder are all reduced at the same rate. At the same time, a milky white aqueous resin dispersion was obtained in the same manner as in the above production example, except that the number of revolutions of the twin screw extruder was decreased to lower the discharge amount of the extruder. The resin aqueous dispersion was filtered through a 100-mesh stainless steel wire mesh, and water was added so that the solid content was 45%.
The average particle size of this aqueous resin dispersion was measured with a laser type particle size distribution analyzer and found to be 7 μm. This aqueous resin dispersion was poor in stability at rest, and easily clogged during filtration, and it was very difficult to handle because the layers were separated in one to several days. After evaporating and solidifying water in the obtained aqueous dispersion, the melting point of the obtained solid was measured with a differential operation calorimeter, and found to be 94 ° C.
A film was produced in the same manner as in Example 1 except that the component (A) of the surface treatment agent was changed to the above.

<Comparative Example 7>
A film was produced in the same manner as in Example 1 except that a surface treating agent consisting of only component (A) was used.

<Comparative Example 8>
The five-layer laminate (P1) of Example 1 was stretched in the same manner as in Example 1 without performing oxidation treatment and application of a surface treatment agent. The obtained 5-layer laminated film was subjected to an oxidation treatment and a surface treatment agent in the same manner as in Example 1, and then dried at 60 ° C. to obtain a 5-layer laminated film having a thickness of 110 μm (the thickness of each layer). 6 μm / 23 μm / 52 μm / 23 μm / 6 μm).

<Test example>
About each film of Examples 1-4, Reference Examples 1-4, and Comparative Examples 1-8 , melt heat transfer suitability, offset printing suitability, and antistatic property were evaluated in accordance with the following procedures.

A bar code printer (trade name B-30-S5, manufactured by Tech Co., Ltd.) and a melt-type resin ink ribbon (trade name B110C, manufactured by Ricoh Co., Ltd.) were used for the melt thermal transfer suitability printing.

(1) Evaluation of ink transferability A barcode was printed on one side of the film under the conditions of 35 ° C and 85% relative humidity, and the ink transferability was evaluated in the following five stages.
5: Good (a clear image can be obtained)
4: Possible (Slight fading is observed in barcode printing, etc., but the practical level is maintained.)
3: Impossible (breaks in bar code printing etc.)
2: Impossible (printed characters are difficult to read)
1: Impossible (almost no ink is transferred)

(2) Evaluation of ink adhesion Bar code was printed on one side of the image receiving film under the conditions of 23 ° C. and 50% relative humidity. The printed matter is conditioned for 2 hours or more under conditions of 35 ° C. and 85% relative humidity, and then cellophane tape (registered trademark) is applied to the surface. The sex was evaluated in the following five stages.
5: Good (no ink peeling)
4: Possible (Slight part of ink peeled, but maintained practical level)
3: Impossible (peeling part was less than 25%)
2: Impossible (peeling part was 25% to 75%)
1: Impossible (peeling part was more than 75%)

For offset printing aptitude evaluation, a printing press (made by Meisei Co., Ltd., trade name RI-III type print suitability tester) and printing ink (made by T & K TOKA, trade name Best Cure 161 (black)) were used. Using.
(1) Ink transfer property After storing the film in an atmosphere of 23 ° C. and 50% relative humidity for 3 days, the ink was printed on the coated surface of the film to a thickness of 1.5 g / m ² . The light reflection density was measured with a light reflection densitometer (trade name Macbeth densitometer manufactured by Colmogen Co., Ltd.).

(2) Ink adhesion After storing the film for 3 days in an atmosphere of 23 ° C. and 50% relative humidity, the ink was printed on the coated surface of the film to a thickness of 1.5 g / m ² , Irradiation was carried out by passing once at a speed of 10 m / min through a portion 10 cm below a metal halide lamp (manufactured by Eye Graphic Co., Ltd., 80 W / cm). Thereafter, the adhesion strength was measured with an adhesion strength measuring device (Kumagaya Riki Kogyo Co., Ltd., trade name Internal Bond Tester). This adhesion strength is measured by applying cellophane tape on the printed surface, attaching an aluminum angle to the application surface, and setting the opposite surface in the same holder. An impact is applied and the peel energy at that time is measured. Here, the adhesive strength of 1.2 kg · cm or more was determined to be acceptable.

(3) Water resistance evaluation After the film was stored for 3 days in an atmosphere of 23 ° C. and 50% relative humidity, the ink was printed on the coated surface of the film so as to have a thickness of 1.5 g / m ² . Irradiation was carried out by passing once at a speed of 10 m / min through a portion 10 cm below a metal halide lamp (manufactured by Eye Graphic Co., Ltd., 80 W / cm). Then, after immersing the printed matter in 23 ° C. water for 3 hours, the printed surfaces were rubbed 30 times in 30 seconds while bending the printed surfaces in water to evaluate the scratching property of the printed surfaces in water. The evaluation criteria are as follows.
5: Good (no ink peeling)
4: Possible (Slight part of ink peeled, but maintained practical level)
3: Impossible (peeling part was less than 25%)
2: Impossible (peeling part was 25% to 75%)
1: Impossible (peeling part was more than 75%)

After conditioning the antistatic film for 2 hours or more in an atmosphere of 23 ° C. and 50% relative humidity, the surface resistivity (JIS K-6911) of the coated surface of the film was measured with an insulation meter (manufactured by Toa Denpa Kogyo Co., Ltd.) , Measured by the trade name DSM-8103) to obtain the surface resistivity. Those having a surface resistivity of 1 × 10 ¹² Ω / □ or less were judged to have good antistatic performance.

The evaluation results of the films of Examples 1 to 4, Reference Examples 1 to 4 and Comparative Examples 1 to 8 are shown in the following table. In addition, about the film of the comparative example 1, since repellency generate | occur | produced at the time of the coating of a surface treating agent, evaluation was not performed.

  The thermoplastic resin film subjected to the surface treatment according to the present invention is excellent in ink transfer property, adhesion and water-resistant adhesion under high temperature and high humidity environment in melt thermal transfer printing, and in ink transfer property and adhesion in offset printing. Excellent in water resistance and water resistance, and additionally has antistatic performance. For this reason, the surface treatment method of this invention can be widely used for manufacture of the thermoplastic resin film for fusion thermal transfer printing or offset printing, and its industrial applicability is high.

Claims (13)

[1] A first step of oxidizing the surface of the thermoplastic resin film,
[2] A second step of applying a surface treatment agent comprising the following components (A) and (B) to the surface of the oxidized thermoplastic resin film, and [3] a thermoplastic resin film coated with the surface treatment agent A method for treating the surface of a thermoplastic resin film, comprising a third step of stretching the film.
Ingredient (A)
A group consisting of a nonionic surfactant, a nonionic water-soluble polymer, a cationic surfactant, and a cationic water-soluble polymer comprising an olefin copolymer (a) to which an unsaturated carboxylic acid or an anhydride thereof is bound. An aqueous dispersion in which at least one selected from the above is used as the dispersant (b) and dispersed in water, wherein the ratio of the weight per solid content of (a) / (b) is 100/1 to 100 / 30 and an aqueous resin dispersion having an average particle size of 5 μm or less
Ingredient (B)
Nitrogen-containing acrylic polymer having a structure obtained by copolymerizing a monomer represented by the following general formula (A)

[In the above formula, A represents —O— or —NH—, R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkylene group having 1 to 18 carbon atoms, or —CH ₂ —CH (OH) — Represents CH ₂ —, R ³ and R ⁴ may be the same or different, and represent an alkyl group having 1 to 3 carbon atoms. The nitrogen atom to which R ³ and R ⁴ are bonded may be a quaternary ammonium salt. ] As the component (B), a nitrogen-containing acrylic polymer having a structure obtained by copolymerizing a monomer in which the nitrogen atom to which R ³ and R ^{4 in} the general formula (A) are bonded is a quaternary ammonium salt is used. The surface treatment method according to claim 1. The thermoplastic resin film used in the first step is a multilayer resin film in which a surface layer (ii) made of a thermoplastic resin is laminated on at least one surface of a base material layer (i) made of a longitudinally stretched thermoplastic resin, and a surface treatment method according to claim 1 or 2, characterized in that the transverse stretching a thermoplastic resin film in the third step. The thermoplastic resin film used in the first step is a multilayer resin film in which a surface layer (ii) made of a thermoplastic resin is laminated on at least one surface of a base material layer (i) made of a thermoplastic resin, and the surface treatment method according to any one of claims 1 to 3, characterized in that the longitudinal stretching a thermoplastic resin film in the third step. The thermoplastic resin film used in the first step comprises a base material layer (i) containing 40 to 100% by weight of thermoplastic resin and 60 to 0% by weight of inorganic fine powder, 25 to 100% by weight of thermoplastic resin and inorganic the surface treatment method according to claim 3 or 4, characterized in that a multi-layer resin film consisting of a surface layer containing the fine powder 75 to 0 wt% (ii). The surface treatment method according to any one of claims 1 to 5 , wherein the porosity of the thermoplastic resin film obtained after the third step is 10 to 60%.

The surface treatment method according to any one of claims 1 to 6 , wherein the thermoplastic resin film used in the first step is made of a polyolefin resin. The surface treatment method according to claim 7 , wherein the polyolefin resin used in the first step is a propylene resin. The oxidation treatment, corona discharge treatment, flame treatment, plasma treatment, glow discharge treatment, and any one of claims 1 to 8, characterized in that at least one treatment selected from the group consisting of ozone treatment The surface treatment method according to 1. The surface treatment method according to any one of claims 1 to 9, the film elongation of the surface treatment agent is characterized in that 100% or more. The surface treatment method according to any one of claims 1 to 10, the surface resistivity of the thermoplastic resin film obtained in the third step is equal to or is 1x10 ¹² Ω / □ or less. Drying temperature of the surface treatment agent applied in the second step, a surface treatment method according to any one of claims 1 to 11, characterized in that high 20 ° C. or higher than the melting point of the solid component (A) . A thermoplastic resin film obtained using the surface treatment method according to any one of claims 1 to 12 .