JP4559147B2 - Adhesive for stencil printing base paper, stencil printing base paper, and method for producing the same - Google Patents

Description

  The present invention relates to an adhesive for stencil printing paper containing a polyolefin resin having a specific composition and a specific medium, a stencil printing paper using the same, and a method for producing the same.

  Conventionally used heat-sensitive stencil sheets are composed of a thermoplastic resin film such as polyester resin or polyvinylidene chloride resin, and an ink-permeable porous support that does not melt and shrink at the melt shrinkage temperature of the film. (For example, synthetic fiber or natural fiber, or thin paper, non-woven fabric, cocoon, Japanese paper, etc. mixed with these) and an adhesive, and a film for preventing fusion of the original or heating element to the film surface Is provided. The thermoplastic resin film used for this type of heat-sensitive stencil printing base paper is very thin with a thickness of about 2 μm in order to increase the sensitivity of heat-sensitive perforation. Furthermore, in recent years, a polyester resin film having a low crystallinity has been used in order to increase the sensitivity of heat-sensitive perforation.

  Thus, since the basic composition of stencil printing paper is a thermoplastic resin film and a porous support, an adhesive that bonds the two is essential, and the selection and bonding method of the adhesive is the quality of the stencil printing paper. It becomes an important factor that influences.

  The adhesive is required to have a strong adhesive force and heat softening and melting at a temperature lower than the perforation temperature of the thermoplastic resin film with a very small amount of application so as not to lower the thermal perforation sensitivity of the base paper. Furthermore, from the viewpoint of improving productivity and not causing damage such as shrinkage to an extremely thin thermoplastic resin film, drying property and adhesiveness in a temperature range of about 80 ° C. or less are required. Further, the adhesive requires water resistance, and when the water resistance is low, the adhesive softens and swells with the printing ink, and the film and the support peel off (delaminate).

  Up to now, many technical proposals have been made regarding adhesives and bonding methods for stencil printing paper. For example, Patent Document 1 discloses a method using a hot melt adhesive. Patent Document 2 discloses an adhesive in which a saturated polyester resin is dissolved in a poorly water-soluble organic solvent (for example, toluene, ethyl acetate, methyl ethyl ketone, etc.), and Patent Document 3 discloses a vinyl acetate resin or an acrylic resin. It is described that it is used after being dissolved in a medium containing a water-soluble alcohol (such as methanol). Patent Document 4 discloses a water-based adhesive in which urethane resin, vinyl acetate resin, vinyl chloride resin and the like are dispersed in water.

JP 59-16790 A JP-A-57-182495 Japanese Patent Publication No.47-17336 JP 2002-254849 A

  However, when using a hot melt adhesive as in Patent Document 1, it is difficult to apply a uniform thin film due to the high viscosity of the adhesive. Further, the adhesive must be heated to the melting point or higher, and a special coating apparatus and a complicated coating process are required. Furthermore, since the thin thermoplastic resin film shrinks due to heating, the adhesive must be applied to the porous support, and if the inter-fiber bond strength of the support is weak, the fibers are peeled off to the adhesive application roller. Therefore, the productivity is poor, and there is a problem that the porous support is deformed when the heating temperature is too high.

In the adhesive of Patent Document 2, since an organic solvent is used, there is a problem that a base material is limited, such as a polyester resin film or synthetic fiber having low crystallinity, which cannot be used because of low solvent resistance. Furthermore, the use of poorly water-soluble organic solvents tends to be restricted from the environmental viewpoint. In Patent Document 3, since a water-soluble alcohol (methanol or the like) is used, the polyester resin film or synthetic fiber having low crystallinity is not affected, but such an adhesive has a small coating amount (for example, 1 g / m). There was a problem with adhesion in ² or less). Furthermore, the adhesives of Patent Documents 2 and 3 have low water resistance, and there is a problem that the film and the support are peeled off by the printing ink described above. When the coating amount is increased, the adhesiveness is improved, but there is a problem that the perforation property of the film is hindered and the print sharpness is lowered.

  Further, the aqueous adhesive disclosed in Patent Document 4 has a problem in adhesiveness with a small coating amount.

  Thus, a water-based adhesive that sufficiently satisfies the conflicting characteristics of adhesive strength and heat-sensitive perforation, has good water resistance, and can be dried at low temperatures and has good productivity has not yet been known.

As a result of intensive studies, the present inventors have found that the above problems can be solved all at once by using an adhesive containing a polyolefin resin having a specific composition.
That is, the gist of the present invention is as follows.
(1) An ethylene- (meth) acrylic acid ester-maleic anhydride copolymer (1) containing 0.1 to 10% by mass of a maleic anhydride component and 12 to 30% by mass of an unsaturated carboxylic acid component It consists of an ethylene-unsaturated carboxylic acid copolymer (2), the solid content mass ratio (1) / (2) of (1), (2) is 95 / 5-50 / 50, and maleic anhydride and some of the components and ports Li olefin resin obtained is neutralized by some volatile basic compound of an unsaturated carboxylic acid component (a), adhesive for stencil printing sheet composed of an aqueous medium.
(2) Number-average particle diameter of 0.3μm or less (1) Symbol mounting of the stencil printing sheet adhesive of the polyolefin resin (A).
( 3 ) A stencil printing base paper composed of a thermoplastic resin film (X) , an adhesive layer (Z), and a porous support (Y) , wherein the adhesive layer (Z) has a maleic anhydride component of 0. 1 to 10% by mass of an ethylene- (meth) acrylic acid ester-maleic anhydride copolymer (1) and an ethylene-unsaturated carboxylic acid copolymer containing 12 to 30% by mass of an unsaturated carboxylic acid component ( 2) and a stencil printing base paper comprising a polyolefin resin (A) having a mass ratio (1) / (2) of (1), (2) of 95/5 to 50/50 .
( 4 ) The thermoplastic resin film (X) and the porous support (Y) are bonded at a drying temperature of 10 to 80 ° C. using the adhesive described in (1) or (2). A method for producing stencil printing paper.

According to the adhesive for stencil printing base paper of the present invention, it is possible to satisfactorily bond the thermoplastic resin film and the porous support even with a small coating amount of, for example, 1 g / m ² or less. The printing base paper has excellent film perforation properties and good print definition. Furthermore, the adhesive layer formed from the adhesive of the present invention has good water resistance and is less likely to cause delamination due to printing ink. In addition, the adhesive of the present invention exhibits excellent adhesiveness even under relatively low temperature ranges such as 80 ° C. or less and drying conditions for a short period of time, and thus is excellent in productivity. Further, when the amount of the organic solvent in the aqueous medium is reduced, it is preferable for the environment.

  The present invention will be described in detail below.

  The polyolefin resin (A) in the adhesive of the present invention needs to contain 0.1 to 30% by mass of the unsaturated carboxylic acid component (A1). The unsaturated carboxylic acid is necessary for finely and stably dispersing or dissolving the polyolefin resin in an aqueous medium (water-based). This amount is easy to make the resin water-based, dispersed particle size, adhesiveness. From the point of balance, such as 0.5-22 mass%, 0.5-15 mass% is more preferable, 1-8 mass% is further more preferable, 1-5 mass% is especially preferable. When content of (A1) exceeds 30 mass%, water resistance and adhesiveness with a base film will fall. When the content of (A1) is less than 0.1% by mass, the adhesiveness is lowered or the resin is difficult to disperse in the aqueous medium.

  The component (A1) is introduced with an unsaturated carboxylic acid or its anhydride. Specifically, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, fumaric acid, crotonic acid, etc. Besides these, unsaturated dicarboxylic acid half esters, half amides and the like can be mentioned. Of these, acrylic acid, methacrylic acid, maleic acid, and maleic anhydride are preferable, and acrylic acid and maleic anhydride are particularly preferable. The unsaturated carboxylic acid component (A1) may be copolymerized in the polyolefin resin (A), and the form thereof is not limited, and examples thereof include random copolymerization, block copolymerization, and graft copolymerization. It is done.

  It is necessary from the point of dispersion stability of the adhesive that a part of the component (A1) is neutralized with a volatile basic compound. Examples of the volatile basic compound include ammonia or various organic amine compounds, preferably ammonia or an organic amine compound having a boiling point of 250 ° C. or lower under normal pressure. When the boiling point exceeds 250 ° C., it becomes difficult to disperse the organic amine compound from the resin coating film by drying, and the water resistance of the adhesive may deteriorate. Specific examples of the organic amine compound include triethylamine, N, N-dimethylethanolamine, aminoethanolamine, N-methyl-N, N-diethanolamine, isopropylamine, iminobispropylamine, ethylamine, diethylamine, and 3-ethoxypropylamine. , 3-diethylaminopropylamine, sec-butylamine, propylamine, methylaminopropylamine, methyliminobispropylamine, 3-methoxypropylamine, monoethanolamine, diethanolamine, triethanolamine, morpholine, N-methylmorpholine, N- Examples thereof include ethyl morpholine. The carboxyl group only needs to be at least partially neutralized with the basic compound described above. From the viewpoint of dispersion stability of the adhesive, the degree of neutralization is preferably 30 to 100%, and 50 to 100%. Is more preferable, 70 to 100% is more preferable, and 80 to 100% is particularly preferable. An anion is generated by neutralizing a part of the carboxyl group (including the acid anhydride), and aggregation between the resin fine particles can be prevented by the electrostatic repulsive force of the anion, and the adhesive can be stabilized.

  When an acid anhydride is introduced, an acid anhydride structure is formed in which the adjacent carboxyl group is dehydrated and cyclized in the dry state of the resin, but in particular in a medium containing a basic compound, a part of the acid anhydride structure is formed. Or all ring-opened to take the structure of a carboxylic acid or a salt thereof.

  Examples of the olefin component (A2) of the polyolefin resin (A) include alkenes having 2 to 6 carbon atoms such as ethylene, propylene, isobutylene, 1-butene, 1-pentene, 1-hexene, and a mixture thereof. You can also. Among these, alkenes having 2 to 4 carbon atoms such as ethylene, propylene, isobutylene and 1-butene are more preferable, and ethylene is particularly preferable. The content of the olefin component is preferably 50% by mass or more, and more preferably 70% by mass or more. When the content of the olefin component is less than 50% by mass, properties derived from the polyolefin resin such as adhesion and water resistance are lost.

  The polyolefin resin (A) preferably contains a (meth) acrylic acid ester component (A3) from the viewpoint of improving adhesiveness. The content of the component (A3) is preferably 0.5 to 40% by mass, and this range is 1 to 35% by mass in order to give good adhesiveness to various thermoplastic resin film substrates. It is more preferable that it is 3-30 mass%, it is especially preferable that it is 5-25 mass%, and it is most preferable that it is 10-25 mass%. When the ratio of the component (A3) is less than 1% by mass, the adhesion with the base film may be lowered. On the other hand, even if the content of the component (A3) exceeds 40% by mass, the properties of the olefin-derived resin are lost, and the adhesion to the base film may be reduced.

Examples of the (meth) acrylic acid ester (A3) component include esterified products of (meth) acrylic acid and alcohols having 1 to 30 carbon atoms. Among these, (meth) acrylic acid and An esterified product with an alcohol having 1 to 20 carbon atoms is preferred. Specific examples of such compounds include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, (meth) acrylic acid. Examples include octyl, decyl (meth) acrylate, lauryl (meth) acrylate, octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, and the like. Mixtures of these may be used. Among these, from the viewpoint of adhesiveness with the substrate film, methyl (meth) acrylate (ethyl) (meth) acrylate, butyl (meth) acrylate, hexyl acrylate, octyl acrylate are more preferable, ethyl acrylate, More preferred is butyl acrylate, and particularly preferred is ethyl acrylate. ("(Meth) acrylic acid" means "acrylic acid or methacrylic acid".)
In addition to the above components, other components may contain about 10% by mass or less of the total polyolefin resin (A). Examples of other components include alkenes having 6 or more carbon atoms such as 1-octene and norbornenes. And dienes, maleic esters such as dimethyl maleate, diethyl maleate, and dibutyl maleate, alkyl vinyl ethers such as (meth) acrylic acid amides, methyl vinyl ether, ethyl vinyl ether, vinyl formate, vinyl acetate, propion Vinyl esters such as vinyl acid vinyl, vinyl pivalate, vinyl versatate, and vinyl alcohol obtained by saponifying vinyl esters with a basic compound, 2-hydroxyethyl acrylate, glycidyl (meth) acrylate, (meth) acrylonitrile, Styrene, substituted styrene , Carbon monoxide, sulfur dioxide, and the like, can also be a mixture thereof.

  Specific examples of the polyolefin resin (A) include ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid-maleic anhydride copolymer, acid-modified polyethylene, acid-modified polypropylene, and acid-modified ethylene-propylene. Examples thereof include resins, acid-modified ethylene-butene resins, acid-modified propylene-butene resins, acid-modified ethylene-propylene-butene resins, or those obtained by further modifying these acid-modified resins with an acrylic ester or the like. In addition, acid modification is modified (specifically, graft modification) with an unsaturated carboxylic acid such as maleic anhydride, maleic acid, itaconic anhydride, itaconic acid or the like. The form of the copolymer may be any of a random copolymer, a block copolymer, a graft copolymer, and the like. Among these, an ethylene- (meth) acrylic acid ester-maleic anhydride copolymer is preferable.

  In addition, as polyolefin resin (A), maleic anhydride content is 0.1-10 mass%, and ethylene- (meth) acrylic acid ester-maleic anhydride copolymer (I) and unsaturated carboxylic acid content are 12. Adhesiveness is improved by using -30 mass%, preferably 15-25 mass% of ethylene-unsaturated carboxylic acid copolymer (II) in combination. A preferable mass ratio is in the range of (I) / (II) = 95/5 to 50/50.

  In the present invention, the polyolefin resin (A) has a melt flow rate at 190 ° C. and a load of 2160 g, which is a measure of molecular weight, usually from 0.01 to 5000 g / 10 minutes, preferably from 0.1 to 1000 g / 10 minutes, more preferably. 1 to 500 g / 10 min, more preferably 2 to 300 g / 10 min, and particularly preferably 2 to 200 g / 10 min. When the melt flow rate of the polyolefin resin (A) is less than 0.01 g / 10 minutes, the adhesiveness with the base film is lowered, or it becomes difficult to make the resin water-based. On the other hand, when the melt flow rate of the polyolefin resin exceeds 5000 g / 10 min, the coating film becomes hard and brittle, and the adhesion to the base film is lowered.

  The synthesis method of the polyolefin resin (A) is not particularly limited, and is generally obtained by high-pressure radical copolymerization of a monomer constituting the polyolefin resin in the presence of a radical generator.

  The adhesive of the present invention is obtained by dissolving or dispersing the above-described polyolefin resin (A) in an aqueous medium. An aqueous medium consists of water and another solvent that can be mixed with water. As the other solvent, a water-soluble organic solvent is particularly preferable. The water-soluble organic solvent is, for example, one having a solubility in water at 20 ° C. of 100 g / L or more. The content of the water-soluble organic solvent is preferably 10 to 98% by mass, more preferably 20 to 95% by mass, still more preferably 40 to 95% by mass, and more preferably 50 to 95% by mass when the total amount of the medium is 100% by mass. Is particularly preferable, and 60 to 95% by mass is most preferable. If the ratio exceeds 98% by mass, the solubility and dispersibility of the resin tend to decrease. The aqueous medium also contains the above-described volatile basic compound for neutralizing the carboxylic acid of the polyolefin resin.

  As the water-soluble organic solvent, those having a boiling point of 100 ° C. or less at normal pressure are preferable from the viewpoint of drying property (productivity) at low temperature. Specific examples thereof include methanol, ethanol, n-propanol, isopropanol, Tetrahydrofuran and acetone are mentioned, and ethanol and isopropanol are particularly preferable from the viewpoint of adhesive stability and low temperature drying property.

  A water-soluble organic solvent having a boiling point of 100 ° C. or lower is less likely to attack the thermoplastic resin film, and when the content is large, excellent adhesion is exhibited even at low temperature and short time drying. Productivity can be increased.

  Usually, the polyolefin resin (A) is present in a dispersed state (emulsion) in the medium, and the particle size is very important for the dry film-forming property and adhesiveness. The number average particle diameter (hereinafter, mn) of the resin particles is preferably 0.3 μm or less, more preferably 0.005 to 0.3 μm, still more preferably 0.01 to 0.2 μm, and 0.01 to 0.1 μm. Is most preferred. Furthermore, regarding a volume average particle diameter (henceforth, mw), 0.5 micrometer or less is preferable, 0.01-0.3 micrometer is more preferable, 0.01-0.2 micrometer is especially preferable. By reducing the particle size, the dry film-forming property and adhesion at a low temperature (especially 80 ° C. or less) are remarkably improved.

  In the present invention, in order to further improve performance such as adhesion to a base film or a porous support and water resistance, a crosslinking agent can be added, and 0.1 to 0.1 parts by mass of polyolefin resin. It is preferable to add 30 mass parts, More preferably, it is 0.5-20 mass parts. When the addition amount of the crosslinking agent is less than 0.1 parts by mass, the degree of improvement in various performances is small, and when it exceeds 30 parts by mass, the performance such as workability is deteriorated. As the crosslinking agent, a crosslinking agent having a self-crosslinking property, a compound having a plurality of functional groups that react with a carboxyl group in the molecule, a metal having a polyvalent coordination site, etc. can be used, of which an isocyanate compound, Melamine compounds, urea compounds, epoxy compounds, carbodiimide compounds, oxazoline group-containing compounds, zirconium salt compounds, titanium salt compounds, aluminum salt compounds, silane coupling agents and the like are preferable. Moreover, you may use combining these crosslinking agents. Among these, an isocyanate compound is preferable from the viewpoint of liquid stability of the adhesive and adhesiveness at low temperature drying.

  Furthermore, the adhesive of the present invention has an organic / inorganic filler, a plate pigment, an inorganic layered compound, a pigment, a pigment dispersant, a wetting agent, an antifoaming agent, a thickening agent, a freezing agent as long as the properties are not impaired. Melting stabilizer, coating film forming aid, antiseptic, antifungal agent, anticorrosive agent, plasticizer, antioxidant, ultraviolet absorber, radical scavenger, weathering agent, flame retardant, leveling agent, anti-waki agent, etc. Can be added. Furthermore, in order to improve initial adhesiveness, other resins such as a polyester resin, a polyurethane resin, and an acrylic resin may be added, and such a resin preferably has a glass transition temperature of 30 ° C. or less. Moreover, you may add a tackifier and wax.

  The stencil printing base paper of the present invention is obtained by laminating a thermoplastic resin film (X) and a porous support (Y) with the above adhesive, and includes a thermoplastic resin film (X) and an unsaturated carboxylic acid component 0. It is comprised from the contact bonding layer (Z) which consists of polyolefin resin (A) containing 0.1-30 mass%, and a porous support body (Y).

  Examples of the thermoplastic resin film (X) constituting the stencil printing base paper include films made of homopolymers and copolymers such as polyester resin, polypropylene resin, polyamide resin, polycarbonate resin, polyvinyl chloride resin, and polyvinylidene chloride resin. Among these, a polyester resin film is preferable, and examples of the polyester resin include polyethylene terephthalate, a copolymer of ethylene terephthalate and ethylene isophthalate, and a copolymer of hexamethylene terephthalate and cyclohexanedimethylene terephthalate. In order to improve the perforation sensitivity, particularly preferred are a copolymer of ethylene terephthalate and ethylene isophthalate, a copolymer of hexamethylene terephthalate and cyclohexanedimethylene terephthalate, and the like.

  For the thermoplastic resin film (X), an organic lubricant such as a flame retardant, a heat stabilizer, an antioxidant, an ultraviolet absorber, an antistatic agent, a pigment, a dye, a fatty acid ester, a wax, or a polysiloxane, if necessary. An antifoaming agent or the like can be blended. Furthermore, easy slipperiness can be imparted if necessary. The slipperiness imparting method is not particularly limited. For example, clay, mica, titanium oxide, calcium carbonate, kaolin, talc, wet or dry silica and other inorganic particles, acrylic acids, styrene, etc. There are a method of blending molecular particles, a method using internal particles, a method of applying a surfactant, and the like.

  Although the thickness of thermoplastic resin film (X) is not specifically limited, Preferably it is 0.1 micrometer-5.0 micrometers, More preferably, it is 0.1 micrometer-3.0 micrometers. When the thickness exceeds 5.0 μm, the piercing property may be deteriorated. When the thickness is less than 0.1 μm, the film forming stability may be deteriorated or the printing durability may be deteriorated.

  Examples of the porous support (Y) in the stencil printing base paper of the present invention include paper-making paper obtained by making short fibers, non-woven fabrics, woven fabrics, screen wrinkles, etc., and non-woven fabrics are more preferably used. It may be used in combination. The porous support (Y) is made of natural fibers such as manila hemp, ridges, honey or pulp, polyester, polyamide, polyphenylene sulfide, vinylon, polyacrylonitrile, polypropylene, polyethylene, or a copolymer thereof. Examples thereof include semi-synthetic fibers such as fibers and rayon. Moreover, the binder fiber etc. which have a core sheath structure may be sufficient.

The basis weight of the porous support (Y) is preferably ^{3g / m 2 ~20g / m 2} , more preferably ^{5g / m 2 ~15g / m 2} . If the basis weight exceeds 20 g / m ² , the ink permeability decreases and the image sharpness decreases. On the other hand, if the basis weight is less than 3 g / m ² , sufficient strength as a support may not be obtained.

  In addition, silicone oil, silicone resin, fluororesin, surfactant, antistatic agent, heat resistance to prevent fusion at the time of drilling on the surface of the thermoplastic resin film (X) that should contact the thermal head It is desirable to provide a thin layer comprising an agent, an antioxidant, organic particles, inorganic particles, a pigment, a dispersion aid, an antiseptic, an antifoaming agent, and the like. The thickness of the anti-fusing thin layer is preferably 0.005 μm to 0.4 μm, more preferably 0.01 μm to 0.4 μm. The method for forming the thin layer is not particularly limited, but it is preferable to apply a solution diluted with water, a solvent, or the like using a roll coater, a gravure coater, a reverse coater, a bar coater or the like, and then dry.

In the present invention, the method of applying the adhesive is not particularly limited, and the adhesive or the diluted adhesive may be applied using a roll coater, gravure coater, reverse coater, bar coater or the like. In addition, the adhesive can be applied to either the thermoplastic resin film (X) or the porous support (Y) or to both, but in consideration of productivity, the thermoplastic resin film ( X) is preferably applied. Coating amount after drying of the adhesive is preferably in the range of 0.1 to 3 g / m ^2, more preferably in the range of 0.2 to 2 g / m ^2, particularly preferably in the range of 0.2~1g / m ² . When the coating amount is less than 0.1 g / m ² , the adhesion is poor, and when it is more than 3 g / m ² , the piercing property is inhibited. The adhesive used in the present invention can form a uniform adhesive layer even with a small coating amount as described above, and has good adhesiveness.

  Since the adhesive of the present invention can be dried at a relatively low temperature of 80 ° C. or lower, deformation of the thermoplastic resin film (X) or the porous support (Y) due to heat can be suppressed. A more preferable drying temperature is 10 to 80 ° C, and 40 to 65 ° C is more preferable. When the drying temperature is low, the drying time tends to be longer. Moreover, when a crosslinking agent is added, it is preferable to perform an aging process at about 20-60 degreeC after drying, and to advance a crosslinking reaction, when improving adhesiveness further.

  Next, a method for preparing an adhesive will be described.

  The method for obtaining the adhesive of the present invention is not particularly limited. For example, the polyolefin resin (A) and an aqueous medium (volatile basic compound, water-soluble organic solvent having a boiling point of 100 ° C. or less, water) can be sealed. A method of heating and stirring in a simple container can be employed.

  As the container, a solid / liquid stirring device or a device known to those skilled in the art as an emulsifier that can appropriately stir a mixture of an aqueous medium and a resin can be used, and pressurization of 0.1 MPa or more is possible. Is preferable. The stirring method and the rotation speed of stirring are not particularly limited.

  After charging the raw material into this apparatus, it is preferably stirred and mixed at a temperature of 40 ° C. or lower, and then the temperature in the tank is kept at 50 to 200 ° C., preferably 60 to 200 ° C., preferably 5 to 5 ° C. The adhesive of the present invention can be obtained by making the resin sufficiently aqueous by continuing stirring for 120 minutes, and then preferably cooling to 40 ° C. or lower with stirring. When the temperature in the tank is less than 50 ° C., it becomes difficult to make the resin water-based. When the temperature in a tank exceeds 200 degreeC, there exists a possibility that the molecular weight of polyolefin resin may fall.

  Moreover, you may add a small amount of the emulsifier mentioned later when preparing the adhesive agent of this invention. The addition amount of the emulsifier is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, based on 100 parts by mass of the polyolefin resin solid content, from the viewpoint of adhesion to the base film and water resistance. It is particularly preferred that the emulsifier is not substantially contained. This is because such a compound remains in the layer even after the formation of the adhesive layer, and plasticizes the layer to deteriorate various performances or to elute from the layer.

  Examples of the emulsifier referred to in the present invention include a cationic emulsifier, an anionic emulsifier, a nonionic emulsifier, and an amphoteric emulsifier. In addition to those generally used for emulsion polymerization, surfactants are also included. For example, anionic emulsifiers include sulfate esters of higher alcohols, higher alkyl sulfonates, higher carboxylates, alkyl benzene sulfonates, polyoxyethylene alkyl sulfate salts, polyoxyethylene alkyl phenyl ether sulfate salts, vinyl sulfosuccinates. Nonionic emulsifiers include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyethylene glycol fatty acid ester, ethylene oxide propylene oxide block copolymer, polyoxyethylene fatty acid amide, ethylene oxide-propylene oxide. Compounds having a polyoxyethylene structure such as copolymers and sorbitan derivatives such as polyoxyethylene sorbitan fatty acid esters And examples of the amphoteric emulsifiers, lauryl betaine, lauryl dimethyl amine oxide, and the like.

  The resin content (solid content concentration) in the adhesive can be appropriately selected depending on the desired coating amount and performance, and is not particularly limited. However, the adhesive has an appropriate viscosity and is thin and uniform. In terms of forming a layer, 1 to 40% by mass is preferable, 1 to 20% by mass is more preferable, 2 to 15% by mass is further preferable, and 3 to 15% by mass is particularly preferable. The method for preparing the resin content is not particularly limited, but an adhesive having a resin content of 15% by mass or more is prepared, and water and / or the above-mentioned water-soluble organic solvent having a boiling point of 100 ° C. or less is prepared there. A method of adding a predetermined amount of is preferable.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

  Various characteristics were measured or evaluated by the following methods.

1. Characteristics of resin (1) Composition of polyolefin resin (A)
Obtained from ¹ H-NMR analysis (manufactured by Varian, 300 MHz). The polyolefin resin was measured at 120 ° C. using orthodichlorobenzene (d ₄ ) as a solvent. The unsaturated carboxylic acid content in the polyolefin resin was calculated from the value obtained by measuring the acid value of the resin according to JIS K5407.
(2) Polyolefin resin (A) melt flow rate (MFR)
It measured by the method of JIS6730 description (190 degreeC, 2160g load).

2. Properties of Adhesive (1) Solid Content Concentration of Adhesive An appropriate amount of the adhesive was weighed and heated at 150 ° C. until the mass of the residue (solid content) reached a constant weight, and the solid content concentration was determined.
(2) Average particle diameter of polyolefin resin The number average particle diameter and the volume average particle diameter were calculated | required using the Nikkiso Co., Ltd. make and micro track particle size distribution analyzer UPA150 (MODEL No. 9340, dynamic light scattering method). Here, the refractive index of the resin used for calculating the particle diameter was set to 1.50.
(3) Pot Life of Adhesive The appearance of the adhesive after leaving the adhesive at room temperature for 30 days was evaluated in the following three stages.
○: No change in appearance.
Δ: Thickening is observed.
X: Solidification, aggregation and precipitation are observed.
(4) Organic solvent content in adhesives Shimadzu Corporation gas chromatograph GC-8A [using FID detector, carrier gas: nitrogen, column packing material (manufactured by GL Sciences): PEG-HT (5%) − Uniport HP (60/80 mesh), column size: diameter 3 mm × 3 m, sample charging temperature (injection temperature): 150 ° C., column temperature: 60 ° C., internal standard substance: n-butanol], and the adhesive with water The diluted product was directly put into the apparatus, and the content of the organic solvent in the medium was determined. The detection limit was 0.01% by mass.

3. Material characteristics The following evaluations were performed using heat-sensitive stencil sheets prepared as in the examples.
(1) Blocking resistance The base paper immediately after production is cut into a size of 10 cm × 10 cm, 50 sheets are stacked, a 5 kg weight is placed thereon, and the base paper is separated from each other after storage at 45 ° C. for 7 days. Then, the degree of peeling at that time was examined.
○: No blocking occurs and the base papers are separated from each other.
Δ: Slightly stuck and sticky, but easily separated.
X: The thing which requires forced peeling.
(2) Water resistance The peel condition between the thermoplastic resin film and the porous support after the base paper immediately after production was immersed in tap water at 30 ° C. for 1 hour was visually evaluated.
○: No peeling Δ: Partial peeling ×: Overall peeling (3) Peeling strength A stencil sheet was cut out with a width of 15 mm, and one day later, a tensile tester (precision universal material testing machine 2020, manufactured by Intesco) The peel strength of the coating film was measured at a pulling speed of 50 mm / min and a pulling angle of 180 degrees.
Next, each of the heat-sensitive stencil sheets thus prepared was allowed to stand at room temperature for 3 days and then used as a manuscript on a facsimile test chart of the Institute of Image Electronics Engineers of Japan using a plate-making printing machine (Gestettner CD760) equipped with a 16 dot / mm thermal head. No. 2 and color test chart no. 11 was used to evaluate the following items.
(4) Halftone dot reproducibility The presence or absence of halftone dots (white spots) in the solid image portion and the halftone image portion was visually evaluated.
○: A clear tone with no halftone dots and a uniform tone.
Δ: There are only a few halftone dots or very small halftone dots, but they are inconspicuous.
X: The dot missing is clearly recognized.
(5) Resolution It was examined whether or not lines and characters of 10 lines / mm could be visually read.
○: Clear and easy to read.
Δ: There are thick lines, thin lines, streaks and spots, and it is difficult to read.
×: Lines and characters cannot be read.
(6) Durability of printing The number of printed sheets was determined so that there was no tearing, wrinkles or elongation of the base paper, and a printed material equivalent to the original printed material was obtained.

Po Li olefin resin was used commercially. The composition of the polyolefin resin used in the production of the following adhesive is shown in Table 1.

Reference example 1
Using a stirrer equipped with a hermetic pressure-resistant 1 liter glass container equipped with a heater, 60.0 g of polyolefin resin (I) [Bondaine HX-8290, manufactured by Atofina ] , 60.0 g of isopropanol (Wako Pure Chemical Industries, Ltd.) Manufactured, boiling point 81 ° C.) 3.7 g of triethylamine (manufactured by Wako Pure Chemical Industries, Ltd., boiling point 89 ° C.) and 176.3 g of distilled water were charged in a glass container and stirred at a rotation speed of 300 rpm. The bottom of the resin particle was not observed at the bottom, and it was confirmed that it was in a floating state. Therefore, while maintaining this state, the heater was turned on and heated after 10 minutes. Then, the system temperature was kept at 140 ° C. and further stirred for 20 minutes. Then, after cooling to room temperature (about 25 ° C.) while stirring with air rotation at 300 rpm, pressure filtration (air pressure 0.2 MPa) with a 300 mesh stainless steel filter (wire diameter 0.035 mm, plain weave) Thus, an aqueous dispersion of a uniform milky white polyolefin resin (I) was obtained. An adhesive E-2 was prepared by adding a mixed solvent of 7/3 (mass ratio) of isopropanol / distilled water so that the solid content concentration was 10% by mass to the obtained aqueous dispersion.

Next , in the Meyer bar so that the adhesive adhesion amount after drying E-2 on the copolymer polyester resin film (biaxially stretched film having a thickness of 2.0 μm) having a melting point of 230 ° C. or less becomes 0.8 g / m ^2. A porous support (Manila hemp thin paper, 8.5 g / m ² ) was bonded in a wet state, and dried at 60 ° C. for 15 seconds. Thereafter, a silicone oil emulsion (SM-8701 manufactured by Toray Dow Corning Silicone Co., Ltd.) was applied to the film surface of this laminate so that the coating amount was 0.2 g / m ² after drying, and dried at 60 ° C. for 15 seconds. A stencil printing base paper was obtained.

Reference example 2
Ethylene-acrylic acid copolymer resin (D) (Primacol 5980I, 20% by mass acrylic acid copolymer, manufactured by Dow Chemical) was used as the polyolefin resin. Using a stirrer equipped with a hermetically sealed 1 liter glass container equipped with a heater, 60.0 g of ethylene-acrylic acid copolymer resin (Primacol 5980I (E), manufactured by Dow Chemical Company), 16.8 g When triethylamine and 232.2 g of distilled water were charged into a glass container and stirred at a rotation speed of the stirring blade of 300 rpm, no sedimentation of resin particulates was observed at the bottom of the container, indicating that it was in a floating state. confirmed. Therefore, while maintaining this state, the heater was turned on and heated after 10 minutes. Then, the system temperature was kept at 120 ° C. and further stirred for 40 minutes. Then, after cooling to room temperature (about 25 ° C.) while stirring with air rotation at 300 rpm, pressure filtration (air pressure 0.2 MPa) with a 300 mesh stainless steel filter (wire diameter 0.035 mm, plain weave) An aqueous dispersion of a slightly cloudy polyolefin resin (D) was obtained. Isopropanol was added to the obtained aqueous dispersion so that the solid concentration would be 10% by mass to prepare an adhesive E-5.

A stencil printing base paper was obtained in the same manner as in Reference Example 1 using E-5.

Example 1
The aqueous dispersions obtained in Reference Examples 1 and 2 were mixed and stirred so that the solid content mass ratio of the polyolefin resins (A) and (D) was 70/30. Isopropanol was added to this liquid so that solid content concentration might be 10 mass%, and adhesive E-9 was prepared.

A stencil printing base paper was obtained in the same manner as in Reference Example 1 using E-9.

Comparative Example 1
An ethylene-maleic anhydride alternating copolymer (v) (manufactured by Aldrich, maleic anhydride content 50 mass%) was used as a polyolefin resin having many unsaturated carboxyl groups. Using a stirrer equipped with a heat-resistant 1-liter glass container with a heater, 60.0 g of resin (v), 15.5 g of triethylamine, and 224.5 g of distilled water were charged into the glass container and stirred. When stirring was performed at a blade rotation speed of 300 rpm, no sedimentation of resin particles was observed at the bottom of the container, confirming that it was in a floating state. Therefore, while maintaining this state, the heater was turned on and heated after 10 minutes. Then, the system temperature was kept at 100 ° C. and further stirred for 10 minutes. Then, after cooling to room temperature (about 25 ° C.) while stirring with air rotation at 300 rpm, pressure filtration (air pressure 0.2 MPa) with a 300 mesh stainless steel filter (wire diameter 0.035 mm, plain weave) Thus, an aqueous dispersion of a substantially transparent polyolefin resin (e) was obtained. Isopropanol was added to the obtained aqueous dispersion so that the solid content concentration was 10% by mass to prepare an adhesive S-1.

A stencil sheet was obtained in the same manner as in Reference Example 1 using S-1.

Comparative Example 2
In Reference Example 2 , sodium hydroxide (made by Wako Pure Chemicals, special grade), which is a non-volatile basic compound, was used instead of triethylamine, and the addition amount was 6.7 g, and the addition amount of water was 233.7 g. An aqueous dispersion of a slightly cloudy polyolefin resin (D) was obtained in the same manner as in Reference Example 2 . Isopropanol was added to the resulting aqueous dispersion so that the solid content concentration was 10% by mass to prepare an adhesive S-2.

A stencil sheet was obtained in the same manner as in Reference Example 1 using S-2.

By using the adhesive of the present invention, excellent adhesiveness was exhibited at a low temperature, for a short time, and with a small coating amount. Further, the obtained stencil printing paper had good performance such as blocking resistance, water resistance, halftone dot reproducibility, resolution, printing durability and the like . Trend shown in the following was observed.

(1) When the unsaturated carboxylic acid in the polyolefin resin was contained and the amount thereof was an appropriate amount, the adhesiveness was good ( Reference Examples 1 and 2 ).
( 2 ) Adhesion was improved by mixing a polyolefin resin having a specific composition (comparison between Example 1 and Reference Example 1 ).

In Comparative Example 1, the content of the unsaturated carboxyl group was outside the range of the present invention, so the adhesiveness was poor, and the water resistance, halftone dot reproducibility, resolution, and printing durability were also poor. In Comparative Example 2, since a non-volatile basic compound was used, the adhesiveness was poor, and the water resistance, halftone dot reproducibility, resolution, and printing durability were also poor.

Claims (4)

Ethylene- (meth) acrylic ester-maleic anhydride copolymer (1) containing 0.1 to 10% by weight of maleic anhydride component and ethylene-unsaturated containing 12 to 30% by weight of unsaturated carboxylic acid component A saturated carboxylic acid copolymer (2), the mass ratio (1) / (2) of (1), (2) is 95/5 to 50/50, and one of the maleic anhydride components parts and a port re-olefin resin (a) formed by neutralized by some volatile basic compound of an unsaturated carboxylic acid component, the adhesive stencil printing sheet composed of an aqueous medium. Stencil sheet adhesive of claim 1 Symbol mounting a number average particle size of 0.3μm or less of the polyolefin resin (A). A stencil printing base paper composed of a thermoplastic resin film (X) , an adhesive layer (Z), and a porous support (Y) , wherein the adhesive layer (Z) has a maleic anhydride component of 0.1 to 10 Ethylene- (meth) acrylic acid ester-maleic anhydride copolymer (1) containing 1% by mass, ethylene-unsaturated carboxylic acid copolymer (2) containing 12-30% by mass of unsaturated carboxylic acid component, and A stencil printing base paper comprising a polyolefin resin (A) having a solid content mass ratio (1) / (2) of 95/1 to 50/50 . Production of stencil printing base paper, wherein thermoplastic resin film (X) and porous support (Y) are bonded at a drying temperature of 10 to 80 ° C. using the adhesive according to claim 1 or 2. Method.