JP6751946B2 - Printing sheet and manufacturing method of printing sheet - Google Patents

Description

The present invention relates to a printing sheet and a method for manufacturing a printing sheet. More specifically, the present invention relates to a technique for improving the printing characteristics, water resistance, weather resistance, antistatic property, etc. of a printing sheet having a coating layer on the surface of a base material.

Conventionally, as a printing sheet, a sheet using paper, a plastic sheet made of polyester, polypropylene, or the like as a base material has been known. In particular, for example, in applications such as posters and outdoor printed materials that require characteristics such as water resistance and tear strength, a plastic sheet or a thermoplastic resin is molded into a sheet by adding an inorganic filler and a small amount of additives. Synthetic paper obtained by the above is mainly used.

In addition, now that environmental protection has become an international issue, reducing the consumption of thermoplastics and paper materials has been greatly studied. From this point of view, inorganic substance powders can be added to thermoplastics. A highly filled thermoplastic composition containing an inorganic substance powder has been proposed and has been put into practical use as a printing sheet as described above (see, for example, Patent Document 1 and the like).

By the way, when a sheet made of the above-mentioned material is considered as a printing application in particular, the surface of the plastic sheet may be modified in order to improve the adhesive force between the ink and the plastic sheet on the printing surface and the color development. There are many. Specifically, a coating liquid made of clay latex or an acrylic polymer is coated to form a coat layer also called an ink receiving layer or a printing receiving layer (for example, Patent Documents 2 to 4). Etc.)

However, for example, when the clay / latex is coated, the whiteness of the printing sheet after coating is low because the clay component has a color, and the color as a substitute for paper may be anxious. .. In addition, since the latex used contains a polystyrene component, it is greatly deteriorated by sunlight, especially ultraviolet rays, and has a problem of yellowing over time.

On the other hand, when a conventional acrylic polymer is coated, the hydrophilic acrylic polymer material added to exert an antistatic effect is highly environmentally dependent, especially in low humidity conditions such as in winter. There is a problem that the antistatic effect is lowered and static electricity is easily generated. When static electricity is generated, clogging occurs during printing and problems such as blocking between sheets occur, which is not preferable. Furthermore, when an acrylic polymer is coated on an olefin-based plastic sheet such as polyethylene or polypropylene, the polarity of the base plastic sheet is small, so that the adhesive strength between the base plastic sheet and the coating liquid depends on the manufacturing conditions. There was also a problem that it was weak and peeled off from the interface between the sheet and the coating even when printed.

In Patent Document 4, a latex of an acrylic polymer having an acid value of 20 to 60 mg of KOH / g and a Tg of less than 35 degrees Celsius as an acrylic polymer, and at least one having a Tg of more than 90 degrees Celsius. Improve high-speed printing suitability at low temperatures with at least two mixtures of acrylic polymer latex, and blend hollow polymer particles into the coating liquid composition to improve the thermal insulation properties of the coat layer. Further, it is disclosed that silica particles having a primary particle size of less than 100 nm are blended in the coating liquid composition to enhance the smoothness of the coat layer. However, when these formulations are applied to the coating liquid composition, there is a concern that the adhesive strength between the plastic sheet as the base material and the coating liquid will be further reduced, and in terms of the antistatic effect as described above. However, no particular improvement could be expected.

International Publication No. WO2014 / 109267 Special Fair 7-20739 JP-A-2015-6793 International Publication No. WO2006 / 051092

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an improved printing sheet and a method for producing the same. The present invention also has excellent printing characteristics, good adhesion between the base material and the coat layer, and good antistatic performance in a printing sheet having a coat layer for receiving ink on at least one surface of the base material. It is an object of the present invention to provide a printing sheet and a method for producing the same, which are less likely to cause problems such as paper jams during printing and are also excellent in various characteristics such as water resistance and weather resistance.

The present inventors have been a problem of a printing sheet having a coat layer formed from a conventional acrylic polymer aqueous emulsion, which is a base material caused by non-polarity of a base material resin such as polypropylene or polyethylene. Poor adhesion between the and the coat layer, poor water resistance of the coat layer due to the water-soluble emulsion of the acrylic polymer, yellowing due to poor weather resistance, paper jams in the printing process due to charging due to high surface resistance, etc. As a result of diligent studies to solve the problem, a predetermined amount of (meth) acrylic acid ester resin particles was added to the acrylic polymer aqueous emulsion, and the (meth) acrylic acid ester resin particles were added to the formed coat layer. By doing so, it was found that the adhesiveness between the base material and the coat layer was improved, the water resistance was improved, the weather resistance was improved, and the antistatic performance was improved by lowering the surface resistance. That is, in the coat layer, the presence of (meth) acrylic acid ester-based resin particles in the continuous phase made of the acrylic polymer causes physical irregularities to be formed at the bonding interface with the base material, resulting in adhesion due to the anchor effect. Improvement of properties can be seen, and the presence of (meth) acrylic acid ester-based resin particles on the surface of the coat layer causes fine irregularities to be formed on the surface of the sheet, and the effect of improving weather resistance due to scattering of incident light can be obtained. Furthermore, since (meth) acrylic acid ester-based resin particles are present in the continuous phase made of the acrylic polymer and form a so-called sea-island structure, a part of the hydrophilic polymer that exhibits antistatic performance added to the continuous phase. Can be aggregated along the interface between the resin particles and the continuous phase, that is, the matrix layer, and good electrical conduction is obtained. Therefore, the hydrophilic polymer is simply dispersed in the coat layer made of the acrylic polymer. This is a case where a good antistatic effect is obtained. The present invention has been reached based on such findings.

That is, in the present invention that solves the above problems, (meth) acrylic acid ester resin particles are blended in a continuous phase made of an acrylic polymer on one side or both sides of the base material at a ratio of 1% by mass or more and 10% by mass or less. It is a printing sheet characterized by having a coated layer made of acrylic.

In one aspect of the printing sheet according to the present invention, the printing sheet in which the volume average particle diameter of the (meth) acrylic acid ester-based resin particles is 1.0 μm or more and 10.0 μm or less is shown.

In one aspect of the printing sheet according to the present invention, the (meth) acrylic acid ester-based resin particles are also a methyl methacrylate homopolymer or a copolymer of methyl methacrylate and another copolymerizable vinyl monomer. A printing sheet, which is a coalesced particle, is shown.

In one aspect of the printing sheet according to the present invention, the printing sheet in which the (meth) acrylic acid ester-based resin particles are particles of a methyl methacrylate-ethylene glycol bismethacrylate copolymer is shown.

In one aspect of the printing sheet according to the present invention, the acrylic polymer forming the continuous phase is an alkyl ester having a hydroxyl group in the side chain of (meth) acrylic acid, or a polyethylene glycol di having an ethylene glycol unit in the molecule. Acrylate, trimethylolpropane EO-modified triacrylate, phenolEO-modified acrylate, mono- or di-alkylaminoalkyl ester of (meth) acrylic acid, acrylamide, methacrylamide, (meth) acrylamide having a methylol group, having an alkoxymethylol group. (Meta) acrylamide; A printing sheet composed of a monomer such as (meth) acrylamide having an alkoxyalkyl group as a part thereof is shown.

In one aspect of the printing sheet according to the present invention, the printing sheet in which the base material contains a polyolefin resin and an inorganic substance powder in a mass ratio of 50:50 to 10:90 is shown. ..

In one aspect of the printing sheet according to the present invention, the printing sheet in which the inorganic substance powder is calcium carbonate powder is shown.

The present invention, which solves the above problems, also coats one or both sides of a base material with an acrylic polymer aqueous emulsion in which (meth) acrylic acid ester-based resin particles are blended in an amount of 1% by mass or more and 10% by mass or less in dry mass. It is a method for manufacturing a printing sheet, which is characterized by being worked.

In one aspect of the method for producing a printing sheet according to the present invention, a base material containing a polyolefin resin and an inorganic substance powder in a mass ratio of 50:50 to 10:90 is extruded into a sheet and stretched. It is characterized in that an acrylic polymer aqueous emulsion containing 1% by mass or more and 10% by mass or less of (meth) acrylic acid ester-based resin particles in a dry mass is applied to one side or both sides of the base sheet through the process. The manufacturing method of the printing sheet is shown.

According to the present invention, in a printing sheet having a coating layer for receiving ink on at least one surface of a substrate, the printing characteristics are excellent, the adhesion between the substrate and the coating layer is good, and the antistatic performance is excellent. It is possible to provide a printing sheet that is good, is less likely to cause problems such as paper jams during printing, and is also excellent in various characteristics such as water resistance and weather resistance.

Hereinafter, the present invention will be described in detail based on the embodiments.

≪Printing sheet≫
The printing sheet according to the present invention comprises a sheet-like base material and a coat layer formed on at least one surface of the base material, and the coat layer is formed in a continuous layer of an acrylic polymer ( Meta) Acrylic acid ester-based resin particles are blended in an amount of 1% by mass or more and 10% by mass or less in terms of dry mass.
The printing sheet according to the present invention is not particularly limited as long as it has a coat layer as described above on at least one surface of the base material, and the other configurations are not particularly limited. An intermediate layer having some function between the base material and the coat layer, for example, a sealant layer for improving the adhesion between the base material and the coat layer, and an internal printing layer for imparting coloring and a pattern to the printing sheet. , A shielding layer or the like, a protective layer or an adhesive layer on the surface of the base material on which the coat layer is not provided, and a protective layer or the like on the surface of the coat layer can be optionally provided.

(1) Base material The material of the base material in the printing sheet according to the present invention is not particularly limited, and may be composed of a plastic-based sheet containing a resin-based material as a main component or a paper-based material. It may be composed of synthetic paper or synthetic paper. Further, as the base material, a sheet made of a thermoplastic containing an inorganic substance powder, which is a highly filled thermoplastic with an inorganic substance powder, particularly a polyolefin resin and the inorganic substance powder in a mass ratio of 50:50 to 10 It is preferable to use a sheet made of a thermoplastic containing an inorganic substance powder in a ratio of: 90 from the viewpoint of environmental resistance and from the viewpoint of improving characteristics such as mechanical strength and heat resistance.

(Resin component)
The resin constituting the plastic sheet or the thermoplastic sheet containing an inorganic substance powder is not particularly limited, and various resins may be used depending on the use and function of the printing sheet. For example, polyolefin resins such as polyethylene resins, polypropylene resins, polymethyl-1-pentene, and ethylene-cyclic olefin copolymers; ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, and ethylene-methacrylic acid copolymers. Functional groups such as polymers, metal salts of ethylene-methacrylic acid copolymers (ionomers), ethylene-acrylic acid alkyl ester copolymers, ethylene-methacrylic acid alkyl ester copolymers, maleic acid-modified polyethylenes, maleic acid-modified polypropylenes, etc. Containing polyolefin resin; polyamide resin such as nylon-6, nylon-6,6, nylon-6,10, nylon-6,12; fragrance of polyethylene terephthalate and its copolymer, polyethylene naphthalate, polybutylene terephthalate, etc. Thermoplastic polyester-based resins such as aliphatic polyester-based resins such as group polyester resins, polybutylene succinates and polylactic acid; polycarbonate resins such as aromatic polycarbonates and aliphatic polycarbonates; atactic polystyrenes, syndiotactic polystyrenes and acrylonitriles- Polystyrene-based resins such as styrene (AS) copolymers and acrylonitrile-butadiene-styrene (ABS) copolymers; polyvinyl chloride-based resins such as polyvinyl chloride and vinylidene chloride; polyphenylene sulfides; polyether sulfone and polyether ketones. , Polyether-based resins such as polyether ether ketones. These can be used individually by 1 type or in combination of 2 or more types.

Among these thermoplastic resins, it is preferable to use a polyolefin resin, an aromatic polyester resin, or an aliphatic polyester resin from the viewpoint of ease of molding, performance, economy, and the like.

Here, the polyolefin-based resin is a polyolefin-based resin containing an olefin component unit as a main component, and specifically, as described above, polypropylene-based resin, polyethylene-based resin, other polymethyl-1-pentene, ethylene- Examples thereof include cyclic olefin copolymers and the like, and a mixture of two or more of them. The above-mentioned "main component" means that the polyolefin component unit contains 50% by mass or more of the olefin component unit, and the content thereof is preferably 75% by mass or more, more preferably 85% by mass. % Or more, more preferably 90% by mass or more. The method for producing the polyolefin resin used in the present invention is not particularly limited, and can be obtained by any of a method using a Ziegler-Natta catalyst, a metallocene catalyst, a radical initiator such as oxygen or peroxide, or the like. It may be a radical.

Examples of the polypropylene-based resin include resins having a propylene component unit of 50% by mass or more, and examples thereof include propylene homopolymers and copolymers with other α-olefins copolymerizable with propylene. Other α-olefins that can be copolymerized with propylene include, for example, ethylene, 1-butene, isobutylene, 1-pentene, 3-methyl-1-butene, 1-hexene, and 3,4-dimethyl-1-butene. , 1-Heptene, 3-Methyl-1-hexene and the like, α-olefins having 4 to 10 carbon atoms are exemplified. Propylene homopolymers include any of isotactics, syndiotactics, atactics, hemiisotactics and linear or branched polypropylenes exhibiting varying degrees of stereoregularity. Further, the above-mentioned copolymer may be a random copolymer or a block copolymer, and may be not only a binary copolymer but also a ternary copolymer. Specifically, for example, ethylene-propylene random copolymer, butene-1-propylene random copolymer, ethylene-butene-1-propylene random ternary copolymer, ethylene-propylene block copolymer and the like can be exemplified. ..

Examples of the polyethylene-based resin include resins having an ethylene component unit of 50% by mass or more. For example, high-density polyethylene (HDPE), low-density polyethylene (LDPE), medium-density polyethylene, linear low-density polyethylene ( LLDPE), ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, ethylene-propylene-butene 1 copolymer, ethylene-butene 1 copolymer, ethylene-hexene 1 copolymer, ethylene-4 methylpentene 1 Examples thereof include a copolymer, an ethylene-octene 1 copolymer, and a mixture of two or more thereof.

Among the above-mentioned polyolefin resins, polypropylene resins are preferably used because they are particularly excellent in the balance between mechanical strength and heat resistance.

(Inorganic substance powder)
Further, as described above, when the base material is an inorganic substance powder-blended thermoplastic plastic sheet, the inorganic substance powder that can be blended in the sheet is not particularly limited, and for example, calcium, magnesium, aluminum, and titanium. , Iron, zinc and other carbonates, sulfates, silicates, phosphates, borates, oxides, or powders of hydrates thereof, and specifically, for example, calcium carbonate. , Magnesium carbonate, zinc oxide, titanium oxide, silica, alumina, clay, talc, kaolin, aluminum hydroxide, magnesium hydroxide, aluminum silicate, magnesium silicate, calcium silicate, aluminum sulfate, magnesium sulfate, calcium sulfate, magnesium phosphate, Examples thereof include barium sulfate, silica sand, carbon black, zeolite, molybdenum, diatomaceous soil, sericite, silas, calcium sulfate, sodium sulfate, potassium titanate, bentonite, and graphite. These may be synthetic or derived from natural minerals, and they may be used alone or in combination of two or more.

Further, the shape of the inorganic substance powder is not particularly limited, and may be in the form of particles, flakes, granules, fibers, or the like. Further, the particles may be spherical in general as obtained by a synthetic method, or may have an indefinite shape as obtained by pulverizing the collected natural minerals. ..

As these inorganic substance powders, calcium carbonate, magnesium carbonate, zinc oxide, titanium oxide, silica, alumina, clay, talc, kaolin, aluminum hydroxide, magnesium hydroxide and the like are preferable, and calcium carbonate is particularly preferable. Further, the calcium carbonate is either so-called light calcium carbonate prepared by a synthetic method or so-called heavy calcium carbonate obtained by mechanically crushing and classifying a natural raw material containing CaCO ₃ as a main component such as limestone. It may be present, and it is possible to combine these, but from the viewpoint of economy, heavy calcium carbonate is preferable.

Here, heavy calcium carbonate is obtained by mechanically crushing and processing natural limestone or the like, and is clearly distinguished from synthetic calcium carbonate produced by a chemical precipitation reaction or the like. The pulverization method includes a dry method and a wet method, but the dry method is preferable from the viewpoint of economy.

Further, in order to enhance the dispersibility or reactivity of the inorganic substance powder, the surface of the inorganic substance powder may be surface-modified in advance according to a conventional method. Examples of the surface modification method include a physical method such as plasma treatment and a method of chemically surface-treating the surface with a coupling agent or a surfactant. Examples of the coupling agent include a silane coupling agent and a titanium coupling agent. The surfactant may be anionic, cationic, nonionic or amphoteric, and examples thereof include higher fatty acids, higher fatty acid esters, higher fatty acid amides, and higher fatty acid salts.

The inorganic substance powder is preferably particles, and the average particle size is preferably 0.1 μm or more and 50.0 μm or less, and more preferably 1.0 μm or more and 15.0 μm or less. The average particle size of the inorganic substance powder described in the present specification refers to a value calculated from the measurement result of the specific surface area by the air permeation method according to JIS M-8511. As the measuring device, for example, a specific surface area measuring device SS-100 manufactured by Shimadzu Corporation can be preferably used. In particular, it is preferable that the particle size distribution does not contain particles having a particle size of 50.0 μm or more. On the other hand, if the particles become too fine, the viscosity may increase significantly when kneaded with the above-mentioned thermoplastic resin, which may make it difficult to manufacture a molded product. Therefore, the average particle size is preferably 0.5 μm or more.

The average particle size of the powdery, flake-like, or granular inorganic substance powder is preferably 10.0 μm or less, and more preferably 5.0 μm or less.

The average fiber length of the fibrous inorganic substance powder is preferably 3.0 μm or more and 20.0 μm or less. The average fiber diameter is preferably 0.2 μm or more and 1.5 μm or less. The aspect ratio is usually 10 or more and 30 or less. The average fiber length and average fiber diameter of the fibrous inorganic substance powder were measured with an electron microscope, and the aspect ratio was the ratio of the average fiber length to the average fiber diameter (average fiber length / average fiber diameter). Is.

When the base material is an inorganic substance powder-blended thermoplastic sheet as described above, the blending ratio (mass%) of the above-mentioned thermoplastic resin contained therein and the inorganic substance powder is as described above. The ratio is preferably 50:50 to 10:90, more preferably 40:60 to 20:80, and even more preferably 40:60 to 25:75. When the proportion of the inorganic substance powder is lower than 50% by mass in the blending ratio of the thermoplastic resin and the inorganic substance powder, a predetermined texture of the inorganic substance powder blended thermoplastic resin composition due to the blending of the inorganic substance powder. This is because physical properties such as impact resistance cannot be obtained, while if it is higher than 90% by mass, molding processing by extrusion molding, vacuum molding, or the like becomes difficult.

(Other additives)
Further, when the base material is the plastic-based sheet or the inorganic substance powder-blended thermoplastic plastic sheet, other additives can be blended as an auxiliary agent in the composition, if necessary. Is. Other additives include, for example, plasticizers, colorants, lubricants, coupling agents, fluidity improvers, dispersants, antioxidants, UV absorbers, flame retardants, stabilizers, antistatic agents, foaming agents and the like. Can be mentioned. These additives may be used alone or in combination of two or more.

(Paper material)
Specific examples of the case where the base material is composed of a paper-based material include a paper base material such as glassin paper, coated paper, wood-free paper, dust-free paper, and impregnated paper, and a thermoplastic resin such as polyethylene on the above paper base material. Examples thereof include laminated paper in which the above is laminated.

(Base material composition)
The base material may be composed of a single sheet made of the above-mentioned material, or a plurality of layers may be laminated to form the base material. When the base material is the plastic-based sheet or the inorganic substance powder-blended thermoplastic plastic sheet, the sheet may be unstretched or may be uniaxially or biaxially oriented in the vertical or horizontal direction. It may be stretched.

The thickness of the base material is not particularly limited, but is usually about 10 μm or more and 300 μm or less, preferably 25 μm or more and 200 μm or less.

When a base material made of a plastic sheet or a thermoplastic sheet containing an inorganic substance powder is used, one side or both sides thereof may be used, if desired, for the purpose of improving the adhesion to the coat layer provided on the surface thereof. Surface treatment can be performed by an oxidation method, an unevenness method, or the like. Examples of the oxidation method include corona discharge treatment, frame treatment, plasma treatment, glow discharge treatment, chromic acid treatment (wet), flame treatment, hot air treatment, ozone / ultraviolet irradiation treatment, and the like. For example, a sandblasting method, a solvent treatment method, and the like can be mentioned. In addition, primer treatment can be applied.

(2) Coat Layer The coat layer of the printing sheet according to the present invention may be provided on only one side of the base material or on both sides. The thickness of the coat layer is not particularly limited, but is preferably 1 μm or more and 10 μm or less, more preferably 2 μm or more and 8 μm or less, and particularly preferably 3 μm or more and 5 μm or less. preferable. When the thickness is within this range, the coat layer functions sufficiently as an ink receiving layer and exhibits ink receiving characteristics such as good colorability and color development, and also has water resistance and surface surface of the printing sheet. Characteristics such as antistatic property and adhesion to ink are also improved.

Thus, in the present invention, in this coat layer, (meth) acrylic acid ester-based resin particles are contained in a continuous phase of the acrylic polymer serving as a matrix in an amount of 1% by mass or more and 10% by mass or less, more preferably 3% by mass. It is added in a proportion of 8% by mass or less, more preferably 4% by mass or more and 6% by mass or less.

When an acrylic polymer aqueous emulsion is used to form such a coat layer, the (meth) acrylic acid ester resin particles are contained in the acrylic polymer aqueous emulsion by 1% by mass or more and 10% by mass in dry mass. % Or less, more preferably 2% by mass or more and 8% by mass or less, and further preferably 2% by mass or more and 6% by mass or less.

In the present invention, (meth) acrylic acid ester-based resin particles that are relatively similar in chemical composition but can retain the particle shape in the continuous phase are blended with the continuous phase of the acrylic polymer to be the matrix. Therefore, the uniform dispersibility of the resin particles in the matrix, the good adhesion at the interface between the continuous phase and the resin particles, and the resulting drop-off resistance of the resin particles from the matrix can be basically ensured. Then, as described above, the presence of the (meth) acrylic acid ester-based resin particles in the continuous phase made of the acrylic polymer in the coat layer causes physical irregularities to be formed at the bonding interface with the base material. Adhesiveness is improved by the anchor effect. Further, the presence of (meth) acrylic acid ester-based resin particles on the surface of the coat layer forms fine irregularities on the surface of the sheet, and the effect of improving weather resistance due to scattering of incident light can be obtained. Furthermore, since (meth) acrylic acid ester-based resin particles are present in the continuous phase made of the acrylic polymer and form a so-called sea-island structure, a part of the hydrophilic polymer that exhibits antistatic performance added to the continuous phase. Can be aggregated along the interface between the resin particles and the continuous phase, that is, the matrix layer, and good electrical conduction is achieved. Therefore, the hydrophilic polymer is simply dispersed in the coat layer made of the acrylic polymer. This is a case where a good antistatic effect is obtained.

If the blending amount of the (meth) acrylic acid ester-based resin particles is smaller than the above range, any or a plurality of improvements in adhesiveness, weather resistance, and antistatic performance cannot be sufficiently exhibited, while the above range. If the amount is larger than the inside, there is a possibility that the coat layer cannot be formed as a continuous layer having sufficient strength.

Further, since the coat layer of the printing sheet according to the present invention is formed by blending (meth) acrylic acid ester-based resin particles as described above, the (meth) acrylic blended therein. By appropriately adjusting the amount and particle size of the acid ester-based resin particles and the thickness of the coated layer to be formed, the surface of the coated layer can be made matte with a certain degree of roughness, or glossiness. It is also possible to make it glossy with increased.
In particular, by forming a matte surface, the weather resistance of the sheet surface can be enhanced.

(Acrylic polymer forming a continuous phase)
The acrylic polymer serving as the matrix of the coat layer includes (meth) acrylic acid, (meth) acrylic acid ester, (meth) acrylamides, and a polymer obtained by using (meth) acrylonitrile as a main monomer component. The term "(meth) acrylic" used in the present specification is used to include both "acrylic" and "methacrylic".

More specifically, the monomer component constituting the acrylic polymer is not particularly limited, but
Acrylic acid, methacrylic acid;
For example, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, hexyl acrylate, n-octyl acrylate, -2 acrylate. -Acrylic acid alkyl ester having 1 to 18 carbon atoms in an alkyl group such as ethylhexyl, lauryl acrylate, stearyl acrylate, palmityl acrylate or cyclohexyl acrylate;
For example, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, hexyl methacrylate, n-octyl methacrylate, -2 methacrylate. -A methacrylic acid alkyl ester having an alkyl group having about 1 to 18 carbon atoms such as ethylhexyl, lauryl methacrylate, stearyl methacrylate, palmityl methacrylate and cyclohexyl methacrylate;
For example, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, monohydroxyethyl phthalate acrylate. Alkyl ester having a hydroxyl group on the side chain of (meth) acrylic acid such as;
For example, polyethylene glycol having an ethylene glycol unit in the molecule (n is preferably 3 or more and 20 or less) diacrylate, trimethylolpropane EO modification (n is preferably 3 or more and 20 or less) triacrylate, phenol EO modification. (It is desirable that n is 3 or more and 20 or less.) Modified acrylate,
For example, alkenyloxyalkyl esters of (meth) acrylic acids such as allyloxyethyl acrylate and allyloxyethyl methacrylate,
For example, an alkyl ester having an alkoxyl group on the side chain of (meth) acrylic acid such as methoxybutyl acrylate, methoxybutyl methacrylate, methoxyethyl acrylate, methoxyethyl methacrylate, ethoxybutyl acrylate, and ethoxybutyl methacrylate;
For example, alkenyl esters of (meth) acrylic acids such as allyl acrylate and allyl methacrylate;
For example, glycidyl acrylate, glycidyl methacrylate, and alkyl esters having an epoxy group on the side chain of acrylic acid such as methyl glycidyl acrylate and methyl glycidyl methacrylate;
For example, mono- or di-alkylaminoalkyl esters of (meth) acrylic acids such as diethylaminoethyl acrylate, diethylaminoethyl methacrylate, methylaminoethyl acrylate, methylaminoethyl methacrylate;
For example, a silicone-modified (meth) acrylic acid ester having a silyl group, an alkoxysilyl group, a hydrolyzable alkoxysilyl group, or the like as a side chain;
For example, acrylamide, methacrylamide;
For example, (meth) acrylamide having a methylol group such as N-methylolacrylamide and N-methylolmethacrylamide;
For example, (meth) acrylamide having an alkoxymethylol group such as N-alkoxymethylolacrylamide (eg, N-isobutoxymethylolacrylamide) and N-alkoxymethylolmethacrylamide (eg, N-alkoxymethylolmethacrylamide, etc.);
For example, (meth) acrylamide having an alkoxyalkyl group such as N-butoxymethylacrylamide or N-butoxymethylmethacrylamide; and
Various acrylic monomers such as acrylonitrile and methacrylonitrile can also be mentioned as monomer components constituting the acrylic resin.
Further, when a crosslinked structure is introduced into the acrylic polymer by a photocuring reaction or the like to increase the film strength of the coat layer, a bifunctional or polyfunctional acrylic monomer, specifically, for example, 1, 4-Butandiol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, the above polyethylene glycol di (meth) acrylate, neopentyl glycol di (meth) hydroxypivalate. Acrylate, dicyclopentanyldi (meth) acrylate, caprolactone-modified dicyclopentenyldi (meth) acrylate, ethylene oxide-modified di (meth) acrylate, allylated cyclohexyldi (meth) acrylate, isocyanurate di (meth) acrylate, Trimethylol propanetri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid-modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide-modified trimethylol propanetri (meth) acrylate , Tris (acryloxyethyl) isocyanurate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, propionic acid-modified dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, caprolactone-modified It is also possible to blend a polyfunctional (meth) acrylate such as dipentaerythritol hexa (meth) acrylate.

These monomer components can be used alone or in combination of two or more.
That is, the acrylic polymer constituting the continuous phase of the coat layer in the present invention may be a homopolymer composed of only one of the various monomer components exemplified above, but the various monomer components exemplified above. It may be a copolymer (copolymer) formed by combining a plurality of the above.
Further, in one embodiment of the present invention, a copolymer containing other monomer components in addition to the above-mentioned monomer components can be used as the acrylic polymer.

The monomer component other than the above examples is not particularly limited as long as it forms a copolymer with the above-mentioned monomer component, and for example, vinyl acetate, vinyl chloride, vinylidene chloride, vinyl lactate, vinyl butyrate, vinyl versatic acid and the like. Examples thereof include vinyl-based monomers such as vinyl benzoate, ethylene, butadiene, and styrene.

The method for forming the coat layer in the printing sheet according to the present invention is not particularly limited, but generally, from the viewpoint of good coatability in forming such a coat layer. , It is desirable to use it in a form dispersed in water / or dissolved in an organic solvent, and in particular, a form dispersed in water, that is, a form of an acrylic polymer aqueous emulsion is desirable. Therefore, it is preferable that the acrylic polymer has the form of an aqueous emulsion at the stage as a raw material for forming a coat layer.

The emulsion polymerization itself in producing an acrylic polymer aqueous emulsion is well known to those skilled in the art. As the surfactant used in the emulsion polymerization, anionic, cationic, amphoteric, and nonionic surfactants can be used alone or in combination of two or more. Of these, those of nonionic and cationic ones are preferable. The nonionic surfactant is not particularly limited, and examples thereof include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ester, sorbitan alkyl ester, and polyoxyethylene sorbitan alkyl ester. is there. The cationic surfactant is not particularly limited, and examples thereof include dodecyltrimethylammonium chloride, stearyltrimethylammonium chloride, N-2-ethylhexylpyridinium chloride and the like, and most preferably a nonionic surfactant. .. Of these, polyoxyethylene alkylphenyl ether is particularly preferable. The surfactant is not particularly limited, but is usually used in an amount of about 1 to 5% by mass based on the total amount of the monomers.

Further, a water-soluble polymer such as gelatin or polyvinyl alcohol may be used in combination as the protective colloid agent.

In addition, as a radical polymerization initiator in emulsion polymerization, a water-soluble type such as potassium persulfate, ammonium persulfate or other persulfate, hydrogen peroxide solution, t-butyl hydroperoxide, azobisamidinopropane hydrochloride or the like, benzoyl Oil-soluble types such as peroxide, diisopropylperoxydicarbonate, cumylperoxyneodecanoate, cumylperoxyoctate, and azobisisobutyronitrile are exemplified, but water-soluble ones are preferable. The polymerization initiator is not particularly limited, but is used, for example, in a proportion of about 0.01 to 0.50% by mass of the total amount of the monomers.

The polymerization reaction is not particularly limited, but is usually carried out under stirring at a temperature of about 35 to 90 ° C., and the reaction time is usually about 3 to 40 hours. Further, by adjusting the pH by adding a basic substance at the start or end of emulsion polymerization, it is possible to improve the leaving stability, freezing stability, chemical stability and the like of the emulsion. In this case, the obtained emulsion is preferably adjusted to have a pH of 5 to 9, and therefore bases such as ammonia, ethylamine, diethylamine, triethylamine, ethanolamine, triethanolamine, dimethylethanolamine, caustic soda, and caustic potash. Sexual substances can be used.

The components constituting the acrylic polymer that forms the matrix of the coat layer are not particularly limited as described above, but in order to improve the antistatic performance of the coat layer, a hydrophilic monomer, for example, (meth) Alkyl ester having a hydroxyl group on the side chain of acrylic acid, polyethylene glycol diacrylate having ethylene glycol unit in the molecule, trimethylolpropane EO modified triacrylate, phenolEO modified acrylate, mono- or di-alkyl of (meth) acrylic acid Aminoalkyl ester, acrylamide, methacrylicamide, (meth) acrylamide having a methylol group, (meth) acrylamide having an alkoxymethylol group; (meth) acrylamide having an alkoxyalkyl group, etc. It is desirable to be there.

Although not particularly limited, an acrylic copolymer or the like can be preferably exemplified as the acrylic polymer that serves as the matrix of the coat layer.

((Meta) acrylic acid ester resin particles)
The (meth) acrylic acid ester-based resin particles blended in the continuous phase made of the acrylic polymer as described above need to be capable of maintaining the particle shape without showing compatibility with the acrylic polymer. Further, in the manufacturing process, it is preferable that the acrylic polymer emulsion or the acrylic polymer solution used for forming the matrix of the coat layer is stable to the solvent, the microemulsion, the monomer and the like. For this reason, it is preferable to use crosslinked resin particles, but the resin is not necessarily limited to crosslinked ones as long as it is stable and can maintain the particle shape in the added system. Even particles can be used.

As the monomer constituting the (meth) acrylic acid ester-based resin particles, any of the monomer groups listed as the monomers constituting the acrylic polymer forming the matrix of the coat layer can be basically used, but the resin particles can be used. An alkyl methacrylate monomer is desirable because it has a certain hardness or higher. That is, it is desired that the (meth) acrylic acid ester-based resin particles are particles of a methyl methacrylate homopolymer or a copolymer of methyl methacrylate and another copolymerizable vinyl monomer.

In particular, when it is a crosslinked resin particle, it is not particularly limited, but as described above, a bifunctional or polyfunctional acrylic monomer, specifically, for example, 1,4-butanediol di (meth). ) Acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, the above polyethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate of hydroxypivalate, dicyclopentanyldi (Meta) acrylate, caprolactone-modified dicyclopentenyl di (meth) acrylate, ethylene oxide-modified di (meth) acrylate phosphate, allylated cyclohexyl di (meth) acrylate, isocyanurate di (meth) acrylate, trimethylol propanthry (meth) ) Acrylate, dipentaerythritol tri (meth) acrylate, propionic acid-modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide-modified trimethylolpropanthry (meth) acrylate, tris (acryloxyethyl) Isocyanurate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, propionic acid-modified dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) It is desirable to blend a polyfunctional (meth) acrylate such as an acrylate, and more specifically, for example, it is desirable that a polyfunctional to polyfunctional acrylic monomer is contained.

The monomer copolymerizable with methyl methacrylate in constituting the resin particles is not particularly limited, and other (meth) acrylic monomers as described above and other copolymerizable vinyl monomers are not particularly limited. Can be used.

Specific examples of the (co) polymer constituting the resin particles include, for example, methyl methacrylate homopolymer, ethyl methacrylate-methyl methacrylate-vinyl acetate copolymer, ethyl methacrylate-ethyl methacrylate-acrylic acid ( 2-Hydroxyethyl) -methyl methacrylate copolymer, methyl methacrylate-vinyl acetate copolymer, methyl methacrylate-methyl methacrylate-methacrylate (2-hydroxyethyl) -styrene copolymer, 1,3-butadiene- Butyl acrylate-methyl methacrylate copolymer, butyl acrylate-butyl methacrylate-methyl methacrylate-styrene copolymer, butyl methacrylate-methacrylic acid (2-hydroxyethyl) -methyl methacrylate-methyl methacrylate copolymer , Methyl methacrylate-methyl methacrylate-styrene copolymer, ethyl acrylate-methyl methacrylate-methyl methacrylate-styrene copolymer, methyl methacrylate [2- (dimethylamino) ethyl] -methyl methacrylate copolymer, acrylic acid Butyl-methyl methacrylate-styrene copolymer, alkyl acrylate-alkyl acrylate (C28) -methyl methacrylate-methyl methacrylate (2-hydroxyethyl) -styrene copolymer, butyl butyl methacrylate-methyl methacrylate-methyl methacrylate Polymer, butyl acrylate-methyl methacrylate-methacrylic acid (2-hydroxyethyl) -styrene copolymer, butyl acrylate-methyl methacrylate copolymer, butyl methacrylate-methyl methacrylate (2-hydroxyethyl) -methacryl Methyl acid acid copolymer, butyl-methacrylic acid-methyl methacrylate copolymer, butyl-acrylic acid (2-hydroxyethyl) -methyl methacrylate-styrene copolymer, butyl-N (hydroxymethyl) acrylate ) Acrylyl-methyl methacrylate copolymer, acrylate-butyl acrylate-methyl methacrylate-styrene copolymer, acrylate-butyl acrylate-methacrylic acid (2-hydroxyethyl) -methyl methacrylate copolymer, methacrylic Amino groups of butyl acid acid-ethyl methacrylate-methyl methacrylate copolymer, butyl acrylate-methacrylic acid-methyl methacrylate-styrene copolymer, acrylic acid ester-methyl methacrylate-aminoethyl methacrylate-styrene copolymer 4, Methyl methacrylate-butyl acrylate-methyl methacrylate-butyl methacrylate-methacrylic acid (2- Hydroxyethyl) copolymer, butyl-methacrylic acid (2-hydroxyethyl) -methacrylic acid-methyl methacrylate-styrene copolymer, butyl acrylate-butyl-methacrylic acid (2-hydroxyethyl) -methacrylic acid Methyl-styrene copolymer, methyl methacrylate-styrene copolymer, methyl methacrylate-ethylene glycol bis methacrylate copolymer, ethyl acrylate-methacrylic acid-methyl methacrylate copolymer, 1,3-butadiene-methacrylic acid Examples thereof include a methyl-styrene copolymer, an ethylacrylic acid-methyl methacrylate copolymer, and a methacrylic acid-methyl methacrylate copolymer, but the present invention is not limited to these.

Of these, resin particles made of a methyl methacrylate-ethylene glycol bismethacrylate copolymer are particularly preferable.

The particle size of the resin particles is not particularly limited and depends to some extent on the thickness of the coat layer to be formed, but for example, 0. It is desirable to have an average particle size of about 2 times or more and 2.0 times or less, more preferably 0.5 times or more and less than 0.8 times. More specifically, for example, the volume average particle size is 1.0 μm or more and 10.0 μm or less, more preferably 1.5 μm or more and 8.0 μm or less, and further preferably 2.0 μm or more and 6.0 μm or less. preferable. With such a particle size range, the resin particles can be blended in the formed coat layer with good dispersibility, and as described above, the base material adhesiveness is improved, the weather resistance is improved, and the antistatic performance is improved. It becomes possible to more preferably exert the desired effect such as.

The shape of the resin particles is not particularly limited, and is not limited to a spherical shape, and may be an elliptical spherical shape or an indefinite shape, but the shape is close to a spherical shape to some extent. It is desirable from the viewpoint of uniform dispersibility in the coat layer. From this point of view, the aspect ratio of the resin particles is preferably 5 or less, more preferably 3 or less, still more preferably 2 or less. The aspect ratio indicates a major axis / minor axis.

Further, as the resin particles, it is desirable that the particle size between the particles is uniform in order to make the in-plane characteristics of the coat layer uniform.

Further, the specific gravity of the resin particles is not particularly limited, but is, for example, 0.9 to 1.5, more preferably about 0.9 to 1.3, for the entire coat layer to be formed. It is desirable because it can be uniformly dispersed.

The method for producing the (meth) acrylic acid ester-based resin particles used in the present invention is not particularly limited, and known suspension polymerization (including pearl polymerization, bead polymerization, etc.) and emulsion polymerization (seed). It can be produced by (including polymerization, etc.) and the like.

(Other additives)
In the present invention, the coat layer may contain other components such as additives other than the above.
Specific examples of the additive include a cross-linking agent, a pH adjuster, a thickener, a fluidity improver, a defoaming agent, a foam suppressant, a surfactant, a mold release agent, a penetrant, a coloring pigment, and a coloring dye. , Fluorescent whitening agents, ultraviolet absorbers, antioxidants, preservatives, fungicides, water resistant agents, ink fixing agents, curing agents, weather resistant materials and the like.

Examples of the cross-linking agent include aldehyde compounds, melamine compounds, isocyanate compounds, zirconium compounds, titanium compounds, amide compounds, aluminum compounds, borates, borates, carbodiimide compounds, and oxazoline compounds. Be done.

Further, it is preferable that the ink fixing agent contains a cationic resin other than the acrylic resin or a polyvalent metal salt. Examples of the cationic resin include polyethyleneimine resin, polyamine resin, polyamide resin, polyamide epichlorohydrin resin, polyamine epichlorohydrin resin, polyamide polyamine epichlorohydrin resin, polydialylamine resin, and dicyandiamide condensate. Examples of the polyvalent metal salt include calcium compounds, magnesium compounds, zirconium compounds, titanium compounds, aluminum compounds and the like. Among these, calcium compounds are preferable, and calcium nitrate tetrahydrate is more preferable.

Further, in the preparation of the coating liquid for forming the coat layer, for example, when an acrylic polymer aqueous emulsion is used as the acrylic polymer to be the matrix of the coat layer, the above (meth) acrylic acid ester-based resin particles are prepared. Or the dispersion in water or the like is added to water which is a dispersion medium of the acrylic polymer aqueous emulsion, and an appropriate stirrer or disperser, for example, a wet colloid mill, an edged turbine, a paddle blade or the like is used. , It can be carried out by usually dispersing for 1 to 5 minutes under a rotation condition of about 500 to 3000 rpm. As described above, since the resin particles used have a relatively similar chemical composition, it is possible to obtain a sufficiently good dispersion even with a mild stirring treatment.

<Manufacturing method of printing sheet>
As a method for producing a printing sheet of the present invention, a conventional method of forming a coat layer on the surface of a base material can be used, for example, as described above (meth) on one side or both sides of the base material. Appropriate methods such as roll coating, blade coating, bar coating, brush coating, spray coating, dipping, etc., of an acrylic polymer aqueous emulsion containing 1% by mass or more and 10% by mass or less of acrylic acid ester resin particles in a dry mass. This can be done by coating and then drying and curing the coat layer. The temperature conditions for drying or curing the coat layer are not particularly limited, but may be, for example, a temperature of 90 to 120 ° C.

In the embodiment in which the sheet made of the thermoplastic plastic containing the inorganic substance powder is used as the base material, for example, the polyolefin resin and the inorganic substance powder are contained in a mass ratio of 50:50 to 10:90. The base material is extruded into a sheet, and the (meth) acrylic acid ester-based resin particles are blended in a dry mass of 1% by mass or more and 10% by mass or less on one side or both sides of the base material sheet through a stretching treatment. The resin aqueous emulsion can be applied by an appropriate method as described above, and then the coat layer is dried and cured. Inorganic substance powder blending In molding a sheet made of thermoplastic, the inorganic substance powder and polyolefin resin can be mixed even if the polyolefin resin and the inorganic substance powder are kneaded and melted before being put into the molding machine from the hopper. Often, the polyolefin resin and the inorganic substance powder may be kneaded and melted at the same time as molding by a molding machine. The same applies to other additives other than the inorganic substance powder. Further, in the melt kneading, it is preferable to knead the polyolefin resin by applying a high shear stress while uniformly dispersing the inorganic substance powder, and it is preferable to knead the mixture with, for example, a biaxial kneader. When the above inorganic substance powder is blended with a polyolefin resin, the higher the temperature, the more odor tends to be generated. Therefore, the melting point of the polyolefin resin is + 55 ° C. or lower, preferably the melting point of the polyolefin resin is + 55 ° C. or lower. More preferably, the treatment is carried out at a temperature at which the melting point of the polyolefin resin is + 10 ° C. or higher and the melting point of the thermoplastic resin is + 45 ° C. or lower.
The molding temperature at the time of extrusion molding into a sheet is preferably the same temperature.

Further, the stretching treatment when molding into a sheet shape is not particularly limited, and is uniaxially or biaxially oriented or multiaxially oriented (stretching by the tubular method, etc.) during or after the molding. ) Can be stretched. In the case of biaxial stretching, sequential biaxial stretching or simultaneous biaxial stretching may be used.

Stretching (for example, longitudinal and / or transverse stretching) of the molded sheet reduces the density of the sheet. As the density decreases, the whiteness of the sheet becomes good.

Hereinafter, the present invention will be described in more detail based on Examples. It should be noted that these examples are specific embodiments and embodiments in order to facilitate understanding of the concept and scope of the present invention, which are disclosed in the present specification and described in the appended claims. The present invention is described only for the purposes of the examples of the above, and the present invention is not limited to these examples.

(Evaluation method)
Each physical property value in the following Examples and Comparative Examples was evaluated by the following method.

(Adhesion evaluation)
In order to examine the adhesion of the coat layer to the substrate, a peeling test with a cellophane adhesive tape was performed.
-Measurement tape Cellophane adhesive tape (width: 24 mm) conforming to JIS Z1522: 2009
-Measurement procedure (1) Take out the tape to a length of about 75 mm.
(2) Stick the tape on the sheet to be measured, and rub the tape with your finger so that it can be seen through. At this time, it is decided to press with the palm of the finger without raising the nail.
(3) Within 5 minutes after applying the tape, lift the end of the tape so that the peeling direction and the coat layer form an angle of about 60 °, and surely separate the tape in 0.5 to 1.0 seconds. The peeled surface is observed, and whether or not the coating layer is attached is visually observed, and the adhesion between the coat layer and the base material is evaluated based on the following evaluation criteria.
To do.
-Evaluation criteria ○ There is no peeling of the coat layer.
Δ The peeling of the coat layer is less than 20%.
× The peeling of the coat layer is 20% or more.

(Water resistance evaluation)
The surface of the coat layer was rubbed with a wet Kimwipe (trade name manufactured by Nippon Paper Crecia) for 10 seconds, and visually observed whether water marks remained, and the water resistance was evaluated based on the following evaluation criteria.
-Evaluation criteria ○ No water marks remain on the surface of the coat layer.
△ A slight amount of water marks appear on the surface of the coat layer.
× A large stain-like water mark remains on the surface of the coat layer.

(Weather resistance evaluation)
In the metal halide weather test, when the black panel temperature was 63 ° C (± 2 ° C), the humidity was 50% (± 5%), and the illuminance was 1200 W / m ² for 24 hours, the state of the coat layer surface before and after the test was visually observed. , L ^* a ^* b ^* Color space The colors were measured in comparison with the chromaticity diagram and evaluated based on the following evaluation criteria.
-Evaluation criteria ○ Before and after the test on the surface of the coat layer, there was almost no change in brightness L ^* and chromaticity a ^* b ^* , and yellowing did not occur substantially.
Δ Before and after the test on the surface of the coat layer, the changes in the lightness L ^* and the chromaticity a ^* were slight, but the values of the chromaticity b ^* increased, and the color was slightly yellowed.
× Before and after the test on the surface of the coat layer, both the lightness L ^* and the chromaticity a ^* b ^* changed, and in particular, the value of the chromaticity b ^* increased remarkably and turned yellow.

(Evaluation of surface resistivity)
Measured according to JIS K 6911: 2006. For the measurement, the sample was used as a 100 mm square sheet, and the measurement was performed under the following conditions.
Temperature 23 ° C, humidity 50%

(Environmental dependence of surface resistivity)
In order to investigate the environment dependence of surface resistivity, immediately after coating the sample, set it to 23 ° C, 30 ° C, 40 ° C, 50 ° C, 60 ° C (humidity conditions are all 50% (± 5% RH) for 30 minutes for a predetermined time). The surface resistivity after holding was measured.

(material)
The components used in the following examples and comparative examples were as follows.

Substrate S1: 36.0 parts by mass of polypropylene homopolymer (melting point 160 ° C.) and heavy calcium carbonate particles 60.0 with an average particle size of 2.2 μm (average particle size by air permeation method) as an inorganic substance powder. An extrusion molding machine equipped with a twin-screw screw (T-die extrusion molding device φ20 mm, L /) containing 2.0 parts by mass and 2.0 parts by mass of sodium alkanesulfonate (alkyl group carbon number (average value) = 12) as a lubricant. D = 25), kneaded at a temperature of 220 ° C. or lower, the kneaded raw material is sheet-molded with a T-die at a molding temperature of 220 ° C., stretched while being wound by a take-up machine, and blended with an inorganic substance powder as a base material. A sheet made of thermoplastic was made. The wall thickness of the sheet thus obtained was 200 μm.

Aqueous emulsion of an acrylic acid ester copolymer containing M1: 1,6-hexanediol dimethacrylate and polyethylene glycol (# 400) diacrylate at a mass ratio of 90:10 (solid content: water =) 20:80 (mass ratio))
Ma: Styrene-acrylic acid containing styrene, benzyl acrylate, butyl acrylate, 1,6-hexanediol dimethacrylate and 2-hydroxyethyl methacrylate in a mass ratio of 84: 26: 32: 0.1: 0.9. Aqueous emulsion of ester copolymer (solid content: water = 20:80 (mass ratio))

-Resin particles B1: Crosslinked polymethylmethacrylate particles (methyl methacrylate-ethylene glycol dimethacrylate copolymer) (volume average particle diameter 2 μm, specific gravity 1.19)
B2: Cross-linked polymethyl methacrylate (methyl methacrylate-ethylene glycol dimethacrylate copolymer) particles (volume average particle diameter 3 μm, specific gravity 1.19)
B3: Cross-linked polymethyl methacrylate (methyl methacrylate-ethylene glycol dimethacrylate copolymer) particles (volume average particle diameter 5 μm, specific gravity 1.19)
B4: Crosslinked polymethylmethacrylate particles (methyl methacrylate-ethylene glycol dimethacrylate copolymer) (volume average particle diameter 1 μm, specific gravity 1.19)
B5: Crosslinked polymethylmethacrylate particles (volume average particle diameter 8 μm, specific gravity 1.20)
B6: Crosslinked polymethylmethacrylate particles (methyl methacrylate-ethylene glycol dimethacrylate copolymer) (volume average particle diameter 10 μm, specific gravity 1.20)
B7: Polymethylmethacrylate homopolymer particles (volume average particle diameter 3 μm, specific gravity (1.19))
Ba: Chemipearl W-400 (manufactured by Mitsui Chemicals, Inc., low molecular weight polyethylene (aqueous dispersion of polyethylene wax (solid content 40%)) (average particle size (Coulter method) 4 μm)

Examples 1-12, Comparative Examples 1-3 and Reference Examples 1-5
The resin aqueous emulsion, the types of resin particles, and the addition amounts were each blended as shown in Table 1 below, and the coating layer coating liquid was prepared by stirring and mixing at 3000 rpm for 3 minutes using an edged turbine. The amount of resin particles added shown in Table 1 is a value in terms of dry mass of each of the resin aqueous emulsion and the resin particles. The coat layer coating liquid prepared in this manner is applied to the surface of the above-mentioned base material by a microgravure method so as to have a predetermined film thickness shown in Table 1, dried at 110 ° C., and used for printing. I created a sheet. The obtained printing sheets were measured with respect to adhesiveness (adhesion of the coat layer to the substrate), surface resistivity, water resistance, and weather resistance under the above-mentioned conditions. The results obtained are shown in Table 2.

In each of the examples of the printing sheet according to the present invention, the coating layer has good adhesion to the base material and has sufficiently good properties in terms of surface resistivity, water resistance, and weather resistance. You can see that it was obtained. On the other hand, in the comparative example in which only the conventional acrylic coat layer is configured, the adhesion of the coat layer is poor, and there are problems in terms of surface resistivity, water resistance, and weather resistance, and yellowing occurs. It was a thing.

Next, Table 3 shows the results of environment-dependent evaluation of the surface resistivity using the printing sheets of Examples 7 and 8 and Comparative Example 1.

As is clear from the results shown in Table 3, in Examples 7 and 8 of the present invention, there is little variation in the surface resistivity due to a change in the environmental temperature, and the change in resistivity is between 23 ° C. and 60 ° C. It was found that the number was less than one order, and the antistatic performance was less dependent on the environment. On the other hand, in Comparative Example 1 having only the conventional acrylic coat layer, the surface resistivity varies greatly due to the change in the environmental temperature, and the resistivity increases sharply especially when the temperature is 40 ° C. As a result, the antistatic performance was highly environmentally dependent.

Claims (8)

A coat layer in which (meth) acrylic acid ester-based resin particles are blended in a proportion of 1% by mass or more and 10% by mass or less in a continuous phase made of an acrylic polymer is provided on one side or both sides of the base material .
The volume average particle diameter of the (meth) acrylic acid ester-based resin particles is 1.0 μm or more and 10.0 μm or less.
The (meth) acrylic acid ester-based resin particles are spherical with an aspect ratio of 5 or less.
Printing sheet. The printing sheet according to claim 1, wherein the (meth) acrylic acid ester-based resin particles are particles of a methyl methacrylate homopolymer or a copolymer of methyl methacrylate and another copolymerizable vinyl monomer. The printing sheet according to claim 1 or 2 , wherein the (meth) acrylic acid ester-based resin particles are particles of a methyl methacrylate-ethylene glycol bismethacrylate copolymer. The acrylic polymer forming the continuous phase is an alkyl ester having a hydroxyl group in the side chain of (meth) acrylic acid, a polyethylene glycol diacrylate having an ethylene glycol unit in the molecule, a trimethylolpropane EO modified triacrylate, and a phenol EO modification. having an alkyl amino alkyl esters, acrylamide, methacrylamide, having a methylol group (meth) acrylamide, having an alkoxy methylol group (meth) acrylamide, and an alkoxyalkyl group - sex a acrylate, mono (meth) acrylic acid - or di The printing sheet according to any one of claims 1 to 3 , which is composed of a part containing a monomer selected from the group consisting of (meth) acrylamide. The printing sheet according to any one of claims 1 to 4, wherein the base material contains a polyolefin resin and an inorganic substance powder in a mass ratio of 50:50 to 10:90. The printing sheet according to claim 5, wherein the inorganic substance powder is calcium carbonate powder. Including a step of applying an acrylic polymer aqueous emulsion containing 1% by mass or more and 10% by mass or less in dry mass of (meth) acrylic acid ester-based resin particles on one or both sides of a base material .
The volume average particle diameter of the (meth) acrylic acid ester-based resin particles is 1.0 μm or more and 10.0 μm or less.
Manufacturing method of printing sheet. A base material containing a polyolefin resin and an inorganic substance powder in a mass ratio of 50:50 to 10:90 is extruded into a sheet, and (meth) acrylic is formed on one side or both sides of the base material sheet through stretching treatment. The method for producing a printing sheet according to claim 7, wherein an acrylic resin aqueous emulsion containing 1% by mass or more and 10% by mass or less of acid ester-based resin particles in a dry mass is applied.