JP2007033871A - Electrophotographic recording sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic recording sheet consisting of a biaxially oriented polypropylene laminated film having excellent printer traveling property, fold-crack resistance, water resistance, and image quality. <P>SOLUTION: The electrophotographic recording sheet comprises the biaxially oriented polypropylene laminated film formed with a surface layer obtained from an ethylenic polymer composition containing a propylene-base polymer (b1), a high-density polyethylene (b2), and a low-density polyethylene (b3) on one surface of a biaxially oriented polypropylene film base material layer obtained from a propylene polymer composition (A) formed by adding inorganic compound powder (a2) to a propylene polymer (a1). The sheet can also be used by being stuck on at least one surface of the base material. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to an electrophotographic recording sheet, and in particular, printer runnability,
The present invention relates to an electrophotographic recording sheet comprising a biaxially stretched polypropylene laminated film excellent in folding resistance, water resistance and image quality.

As one of copying and printing technologies, electrophotographic technology is widely used. This technology is a toner image formed by forming an image corresponding to an electrostatic latent image with toner powder charged with an electrostatic latent image (electrostatic latent image) formed on a photosensitive drum. Is transferred onto a recording sheet such as plain paper and fixed by heat or the like. As a main method for forming an electrostatic latent image on a photosensitive drum, a so-called plain paper copying method (PPC) in which a charge corresponding to a subject image such as a document is charged on the photosensitive drum to form an electrostatic latent image on the photosensitive drum. After digitizing an electronic subject image or subject image, the electronic data (electronic signal) is turned on / off according to the electronic signal while scanning the laser beam using a polygon mirror (rotating polygon mirror). A so-called laser beam printer method (LBP) is used in which an electrostatic latent image is formed on the photosensitive drum. In particular, laser beam printers are attracting attention as POD (Print On Demand) machines.

In general, paper is widely used as a recording sheet for electrophotography, but water resistance is required for outdoor advertising posters, restaurant menus, supermarkets, convenience stores, mass-market stores, etc. Therefore, one or more thermoplastic resin layers are formed on both sides of the paper substrate, and the outermost layer on at least one side is laminated with a layer made of polymethylpentene (Patent Document 1) or calcium carbonate and An electrophotographic recording sheet (Patent Document 2) composed of a biaxially stretched laminated sheet obtained from a resin composition mainly composed of a propylene homopolymer including high-density polyethylene has been proposed. It is described as having excellent water resistance.
However, the laminated water-resistant paper obtained by extruding and laminating a thermoplastic resin as the outermost layer does not have a porous cushion layer, and also has an electrophotographic surface layer made of a resin composition mainly composed of a propylene homopolymer. The recording sheet for use does not have sufficient toner powder adhesion.

JP 2005-88573 A (Claim 1) JP 2002-62678 A (Example)

Accordingly, an object of the present invention is to obtain an electrophotographic recording sheet composed of a biaxially stretched polypropylene laminated film which is excellent in printer runnability, folding resistance, water resistance and image quality and has a paper-like texture.

The present invention provides a biaxially oriented polypropylene film substrate layer obtained from a propylene polymer composition (A) obtained by adding an inorganic compound powder (a2) to a propylene polymer (a1),
Propylene polymer (b1), high density polyethylene (b2) and low density polyethylene (b
3), an electrophotographic recording sheet comprising a biaxially stretched polypropylene laminated film on which a surface layer obtained from the ethylene polymer composition (B) is formed, preferably the surface roughness of the surface layer (three-dimensional center plane) Average roughness: SRa) is in the range of 0.2 to 0.6 μm and glossiness is in the range of 7 to 60%, and the light transmittance of the biaxially oriented polypropylene laminated film is 10 to 55% and the density is 0.50. An electrophotographic recording sheet comprising a biaxially stretched polypropylene laminated film in a range of 0.90 g / cm ³ is provided.
Moreover, the present invention provides an ethylene polymer composition (B
) Is 85 to 50% by mass of the propylene polymer (b1), 3 to 30% by mass of the high density polyethylene (b2), and 10 to 45% by mass (b1 + b2 + b3) of the low density polyethylene (b3).
= 100 mass%), the propylene polymer (b1) comprises a propylene homopolymer (b1-1) and a propylene / α-olefin random copolymer (b1-2). And the propylene polymer composition (A) is a propylene polymer (a1)
Inorganic compound powder composed of 55 to 92% by mass, 0.5 to 20% by mass of calcium carbonate having an average particle size of 0.5 to 5 μm, an 80% cumulative frequency particle size of 3 μm or less, and 1 to 10% by mass of titanium oxide ( a recording sheet for electrophotography, characterized in that the electrophotographic recording sheet is bonded to at least one side of a paper substrate. It is to provide.

The electrophotographic recording sheet comprising the biaxially stretched polypropylene laminate film of the present invention is excellent in printer runnability, folding resistance, water resistance and image quality.

The present invention will be described in further detail.
[Propylene polymer composition (A)]
The propylene polymer composition (A) according to the present invention is a composition obtained by adding an inorganic compound powder (a2) to a propylene polymer (a1) described later, and biaxially stretching by biaxially stretching it. It becomes a polypropylene film base material layer.
The addition amount of the inorganic compound powder (a2) in the propylene polymer composition (A) with respect to the propylene polymer (a1) is the kind of the inorganic compound, as well as the haze and total light transmittance of the resulting biaxially stretched polypropylene laminated film. Depending on how much the density is set, it is usually 1.5 to 30% by mass, preferably 3 to 25% by mass.
By adding this inorganic compound powder (a2) to the propylene polymer (a1), the concealability, density, haze, cushioning and total light transmittance of the biaxially stretched polypropylene film substrate layer are adjusted to appropriate values. I can do it.

Particularly when calcium carbonate, more preferably titanium oxide, is used in combination as the inorganic compound powder (a2), the density is 0.50 to 0.90 g / cm ³ , more preferably 0.55 to 0.
. 85 g / cm ³ , haze of 90% or more, preferably 91 to 95%, light transmittance of 10
A biaxially oriented polypropylene laminate film of ~ 55%, preferably 10-27% is obtained.
In addition to the inorganic compound powder (a2), the propylene-based polymer composition (A) according to the present invention includes a heat stabilizer, a weather stabilizer, an ultraviolet absorber, a lubricant, a slip agent, a nucleating agent, an antiblocking agent, Various additives such as antistatic agents, antifogging agents, pigments, dyes and the like that are generally known to be added to polyolefins may be added as long as the object of the present invention is not impaired.

It is preferable to add an antistatic agent to the propylene polymer composition (A) according to the present invention. As such an antistatic agent, various known antistatic agents, for example,
Alkylamines such as alkyldiethanolamine, alkyldiethanolamide, alkyldiethanolamine fatty acid esters and derivatives thereof;
Higher alcohols having 8 to 18 carbon atoms such as lauryl alcohol, myristyl alcohol, cetyl alcohol, cetostearyl alcohol, stearyl alcohol or behenyl alcohol;
Glycerin esters of higher fatty acids having 8 to 24 carbon atoms such as palmitic acid, stearic acid, oleic acid, linoleic acid or linolenic acid;
Partial fatty acid esters of polyhydric alcohols such as glycerin, ethylene glycol, propylene glycol or pentaerythritol;
The following surfactants such as nonionic surfactants, cationic surfactants, anionic surfactants and amphoteric surfactants;

(Nonionic surfactant)
Ethylene oxide adduct (number average molecular weight 150 to 200,000) of the higher alcohol, higher fatty acid (carbon number 8 to 24) or higher alkylamine (carbon number 8 to 24): polyalkylene which is an ethylene oxide adduct of glycol Glycol (number average molecular weight 1
50-6,000) higher fatty acid esters: ethylene glycol, propylene glycol, glycerin, pentaerythritol, sorbitan and other divalent to octavalent or higher polyhydric alcohols having 2 to 18 carbon atoms, ethylene oxide of higher fatty acid esters Adduct (number average molecular weight 250 to 30,000): ethylene oxide adduct of higher fatty acid amide (number average molecular weight 200 to 30,000) and polyhydric alcohol alkyl (carbon number 3 to 60) ether ethylene oxide adduct ( Ethylene oxide addition type nonionic surfactant such as number average molecular weight 120-30,000):
Fatty acid (carbon number 3-60) ester of polyhydric alcohol, alkyl (carbon number 3-60) ether of polyhydric alcohol:
Polyhydric alcohol (C3-60) such as fatty acid (C3-60) alkanolamide
) Type nonionic surfactants;

[Anionic surfactant]
C8-24 saturated or unsaturated fatty acids such as palmitic acid, stearic acid, oleic acid, linoleic acid or linolenic acid and higher fatty acids such as ether carboxylic acids or alkali metal salts, alkaline earth metal salts, ammonium salts, alkyls Amines (C1-20
) Salts and salts such as alkanolamine (C2-C12, for example mono-, di- and triethanolamine) salts:
The higher alcohol sulfate ester salt and the higher alcohol ethylene oxide (
1-10 mol) Sulfate esters such as higher alkyl ether sulfates such as sulfates of adducts:
Alkylbenzenesulfonates such as sodium dodecylbenzenesulfonate, alkylsulfonates, alkylnaphthalenesulfonates, sulfosuccinic acid dialkyl ester types, hydrocarbon (eg alkane, α-olefin) sulfonates and Igepon T
C10-20 sulfonates such as molds:
Phosphoric acid ester salts such as the higher alcohol ethylene oxide adduct phosphoric acid ester salt and alkyl (carbon number 4 to 60) phenol ethylene oxide adduct phosphoric acid ester salt;

[Cationic surfactant]
C3-C100 tetraalkylammonium salts such as lauryltrimethylammonium chloride, didecyldimethylammonium chloride, dioctyldimethylammonium bromide and stearyltrimethylammonium bromide, C3-C3 such as lauryldimethylbenzylammonium chloride (benzalkonium chloride) 80 trialkylbenzylammonium salts, C2-C60 alkylpyridinium salts such as cetylpyridinium chloride, C2-C4 polyoxyalkylene trialkylammonium salts such as polyoxyethylene trimethylammonium chloride and stearamide ethyl diethyl Quaternary ammonia such as sapamine-type quaternary ammonium salts such as methylammonium and methosulfate Salt type cationic surfactants:
Inorganic acid salts or acetic acid, propionic acid, lauric acid, oleic acid such as hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid of higher aliphatic amines having 12 to 60 carbon atoms such as laurylamine, stearylamine, cetylamine, hardened beef tallow amine and rosinamine Organic acid salts having 2 to 22 carbon atoms such as benzoic acid, succinic acid, adipic acid and azelaic acid, inorganic acid salts or organic acid salts such as ethylene oxide adducts of aliphatic amines having 1 to 30 carbon atoms and triethanol 3 to 3 carbon atoms such as amine monostearate and stearamide ethyl diethyl methyl ethanol amine
30 amine salt type cationic surfactants such as inorganic or organic acid salts of tertiary amines;

[Amphoteric surfactant]
Amino acid type amphoteric surfactants such as sodium propionate of higher alkylamines having 8 to 24 carbon atoms:
Betaine-type amphoteric surfactants such as alkyl dimethylbetaines having 12 to 18 carbon atoms:
Sulfate ester-type amphoteric surfactants such as higher alkylamine sulfate sodium salt and hydroxyethylimidazoline sulfate sodium salt having 8 to 24 carbon atoms:
Sulfate-type amphoteric surfactants such as pentadecyl sulfotaurine and imidazoline sulfonic acid:
Phosphate ester-type amphoteric surfactants such as phosphate ester amine salts of glycerin higher fatty acid esterified products;
However, it is not limited to these antistatic agents.
These antistatic agents may be used alone or in combination of two or more. The addition amount of the antistatic agent is usually 300 to 30000 with respect to 100 parts by mass of the propylene polymer composition (A).
ppm, preferably 500 to 25000 ppm. Addition amount of antistatic agent is 300pp
If it is less than m, when the obtained biaxially stretched polypropylene laminated film is used as an electrophotographic recording sheet, the electrophotographic recording sheet is easily charged during printing, and the electrophotographic recording sheet is multi-feed particularly when performing double-sided printing. There is a risk of causing. On the other hand, when it exceeds 30000 ppm,
The water resistance of the resulting electrophotographic recording sheet may be impaired. By adding an antistatic agent in the above range to the propylene polymer composition (A), the surface resistivity of the surface layer of the resulting electrophotographic recording sheet is in the range of 1 × 10 ⁷ to 1 × 10 ¹³ Ω. Can be.

<Propylene polymer (a1)>
Propylene polymer constituting the biaxially oriented polypropylene film substrate layer according to the present invention (a
1) is a polyolefin resin that is generally produced and sold under the name of polypropylene, and usually has a density of 0.890 to 0.930 g / cm ³ and an MFR (ASTM D1238 load of 2160 g, temperature of 230 ° C.) of 0.5. -60 g / 10 min, preferably 0.5-10 g /
A homopolymer of propylene for 10 minutes, more preferably 1-5 g / 10 minutes, or propylene and other small amounts, for example 2 mol% or less of α-olefins such as ethylene, 1-butene, 1-hexene, It is a random copolymer with 1-octene or the like.
These propylene polymers (a1) are compositions composed of one or more polymers, for example, a composition of propylene homopolymers and propylene / α-olefin random copolymers having different molecular weights. There may be. Among these, a homopolymer of propylene,
Alternatively, a random copolymer of 1 mol% or less and a polymer having high isotacticity, particularly a homopolymer of propylene is preferable because a biaxially stretched polypropylene laminated film having high rigidity and excellent heat resistance can be obtained.
This propylene polymer (a1) is blended with the inorganic compound powder (a2) and biaxially stretched to form the biaxially stretched film base layer of the biaxially stretched polypropylene laminate film of the present invention.

<Inorganic compound powder (a2)>
The inorganic compound powder (a2) according to the present invention is a powder of calcium carbonate, clay (kaolin), calcined clay, talc, silica, zeolite, barium sulfate, aluminum sulfate, titanium oxide or the like, and usually has an average particle size of 5 μm. In the following, it is preferably in the range of 0.1 to 1.5 μm. Among these inorganic compound powders, calcium carbonate and titanium oxide are preferable in that a biaxially stretched polypropylene laminated film having excellent whiteness without unevenness can be obtained.
Further, by using calcium carbonate, preferably calcium carbonate and titanium oxide in combination, the density is 0.50 to 0.90 g / cm ³ , more preferably 0.55 to 0.85 g / cm ^3.
A biaxially stretched polypropylene laminated film having a light transmittance of 10 to 55%, preferably 12 to 50% is obtained. The calcium carbonate preferably has an average particle size in the range of 0.5 to 5 μm, more preferably 1 to 1.5 μm. The maximum particle size is preferably 5 μm or less. The particle size of calcium carbonate is a value measured by a laser diffraction scattering method.
When calcium carbonate and titanium oxide to be added to the propylene polymer (a1) are used in combination, calcium carbonate is preferably 0.5 to 20% by mass, more preferably 1-1.
5% by mass, and titanium oxide is preferably 1 to 10% by mass, more preferably 1.5 to 10%.
[Propylene polymer (a1) + calcium carbonate + titanium oxide = 100% by mass
].
If the blending amount of calcium carbonate is less than 0.5% by mass, the concealability of the resulting biaxially stretched polypropylene laminate film may be inferior. On the other hand, if it exceeds 20% by mass, the appearance of the biaxially stretched polypropylene laminate film is impaired. There is a fear. Moreover, when the compounding amount of titanium oxide is less than 1% by mass, the concealability and whiteness of the obtained biaxially stretched polypropylene laminate film may be slightly inferior. There is a possibility that the appearance is damaged.
In the calcium carbonate according to the present invention, preferably the calcium carbonate particles having a particle size of 3 μm or less are 80% by mass (80% cumulative frequency particle size) or more, preferably 90% by mass (90% cumulative frequency particle) of the whole calcium carbonate. (Diameter) or more. When calcium carbonate having such a particle size distribution and average particle size is used, the size of voids in the film due to the calcium carbonate particles becomes uniform, so that a film with excellent non-uniform hiding power and whiteness can be obtained.
In order to obtain a film having uniform voids in the film and excellent in hiding power and whiteness, it is more preferable that the water content of calcium carbonate used is 0.5% by mass or less. The water content of calcium carbonate is a value measured according to JIS K 5101.
Furthermore, the surface of the particles of the calcium carbonate according to the present invention may be surface-treated with, for example, a higher fatty acid, preferably a higher fatty acid having 10 to 28 carbon atoms. By treating the particle surface with such a higher fatty acid, it is possible to prevent the occurrence of foreign matters, fish eyes and the like due to secondary aggregation of calcium carbonate, and to obtain a biaxially stretched polypropylene laminated film exhibiting a good appearance. .
Specific examples of the higher fatty acid include decanoic acid, undecanoic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, and serothin. Acid, saturated higher fatty acids such as heptacosanoic acid [CH ₃ (CH ₂ ) nCOOH, n = 8 to 26]; oleic acid (cis),
Elaidic acid (trans), cetreic acid, erucic acid (cis), brassic acid (tr
ans), unsaturated higher fatty acids such as linoleic acid, linolenic acid, arachidonic acid, and the like,
Of these, saturated higher fatty acids, particularly stearic acid, are preferred.
The titanium oxide preferably has an average particle size in the range of 0.1 to 0.5 μm. Titanium oxide is also called titanium white, and there are a rutile type and an anatase type, but the rutile type is preferable because of its excellent hiding power. In addition, when the titanium oxide according to the present invention has an alumina-treated surface, the resulting biaxially stretched polypropylene laminate film is excellent in appearance, and the L * value is 90 or more. The electrophotographic recording sheet using is preferable in that it gives a high-class feeling and can express the gradation more clearly when recording an image having a gradation. L * value means that 10 films are overlaid on white paper and Sp
It is the value measured using electro Eye (made by Gretag Macbeth). The particle diameter of titanium oxide is a value measured by a light scattering method.

[Ethylene polymer composition (B)]
The ethylene polymer composition (B) according to the present invention is a propylene polymer (b1) described later.
, A composition containing high-density polyethylene (b2) and low-density polyethylene (b3), preferably 85 to 50% by mass, more preferably 80 to 55% by mass, of propylene-based polymer (b1),
Preferably high density polyethylene (b2) is 3-30% by weight, more preferably 5-25% by weight and preferably low density polyethylene (b3) is 10-45% by weight, more preferably 15%.
It is a composition in the range of -40 mass% (b1 + b2 + b3 = 100 mass%), and is a composition which forms the surface layer of the biaxially-stretched polypropylene film base material layer obtained from the said propylene polymer composition (A). .
Such an ethylene-based polymer composition (B) usually has a peak temperature (Tp) determined from a crystal melting curve based on a differential scanning calorimeter (DSC), and low density polyethylene (b3
), 95-1 corresponding to high-density polyethylene (b2) and propylene polymer (b1)
One to a plurality of each in the range of 25 ° C, 120 to 138 ° C, and 125 to 170 ° C.
MFR (melt flow rate; ASTM D-123) of ethylene polymer composition (B)
8 load; 2160 g, temperature; 230 ° C.) is not particularly limited as long as it has film-forming ability, but is usually in the range of 0.5 to 20 g / 10 minutes, preferably 2 to 10 g / 10 minutes.
The ethylene polymer composition (B) according to the present invention comprises three components of the propylene polymer (b1), high density polyethylene (b2) and low density polyethylene (b3),
When a composition lacking any one component is used as the surface layer, toner adhesion may be inferior.
As a propylene polymer (b1) which is one of the components of the ethylene polymer composition (B) according to the present invention, a propylene homopolymer (b1-1) and a propylene / α-olefin random copolymer (b1) -2) is preferable because a surface layer with better toner adhesion can be obtained. When the propylene homopolymer (b1-1) and the propylene / α-olefin random copolymer (b1-2) are used in combination, the ratio [(b1-1) / (b1-2
); Weight ratio] is preferably in the range of 95/5 to 60/40.
The ethylene polymer composition (B) according to the present invention is mainly composed of the propylene polymer (b1) and the propylene polymer (b1) from the viewpoint of heat resistance of the obtained electrophotographic recording sheet.
Also in b1), it is preferable that a propylene homopolymer (b1-1) is a main component.
When producing the biaxially stretched polypropylene laminated film according to the present invention, the ethylene polymer composition (B) according to the present invention comprises a propylene polymer (b1) and a high density polyethylene (b2).
) And low density polyethylene (b3) may be mixed by a dry blend or the like at a desired ratio and charged into a molding machine, or may be previously melt-kneaded. Also, in a series of polymerization systems, propylene polymer (b1), high density polyethylene (b2) and low density polyethylene (b3)
May be polymerized to obtain an ethylene polymer composition (B), or these methods may be combined.
Propylene polymer (b1), high density polyethylene (b2), and low density polyethylene (b3) which are components contained in the ethylene polymer composition (B) or ethylene polymer composition (B) according to the present invention Are usually added to polyolefins such as heat stabilizers, weathering stabilizers, UV absorbers, lubricants, slip agents, nucleating agents, antiblocking agents, inorganic compound powders, antistatic agents, antifogging agents, pigments, dyes, etc. It is also possible to add various known additives within a range that does not impair the object of the present invention.

<Propylene-based polymer (b1)>
The propylene polymer (b1) which is one of the components contained in the ethylene polymer composition (B) according to the present invention is a propylene homopolymer (b1-1), propylene and ethylene, 1-
Random copolymers or block copolymers (b1-2) with other α-olefins such as butene, 1-hexene and 1-octene. The propylene polymer (b1) may be used singly or in combination of two or more polymers, but is preferably a propylene homopolymer (b1-1) and a propylene / α-olefin random copolymer (b1-2). Are preferably used.
The propylene homopolymer (b1-1) usually has a peak temperature (Tp) determined from a crystal melting curve based on DSC in the range of 160 to 170 ° C.
The propylene / α-olefin random copolymer (b1-2) is preferably D
The peak temperature (Tp) obtained from the crystal melting curve based on SC is in the range of 125 to 158 ° C.
MFR (melt flow rate; ASTM) of the propylene-based polymer (b1) according to the present invention
D-1238 (load: 2160 g, temperature: 230 ° C.) is not particularly limited as long as the composition mixed with high density polyethylene (b2) and low density polyethylene (b3) described later has film-forming ability, but usually 0.5 to 20 g. / 10 minutes, preferably in the range of 2 to 10 g / 10 minutes.

<High-density polyethylene (b2)>
The high density polyethylene (b2) which is one of the components contained in the ethylene polymer composition (B) according to the present invention is an ethylene homopolymer or ethylene and propylene, 1-butene,
Copolymers with other α-olefins such as 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, etc., and usually an ethylene system having a density of 0.945 to 0.970 g / cm ³ A polymer that is generally manufactured and sold as high-density polyethylene (HDPE) or that is obtained in a polymerization system.
The high density polyethylene (b2) usually has a peak temperature (Tp) determined from a crystal melting curve based on DSC in the range of 120 to 138 ° C.
MFR (melt flow rate; ASTM) of high density polyethylene (b2) according to the present invention
D-1238 load 2160 g, temperature 190 ° C. is the same as the propylene polymer (b1).
) And the composition mixed with the low density polyethylene (b3) described below, but not limited as long as it has a film-forming ability, usually 0.1 to 50 g / 10 minutes, preferably 0.2 to 35 g.
/ 10 min.

<Low density polyethylene (b3)>
Low density polyethylene (b3), which is one of the components contained in the ethylene polymer composition (B) according to the present invention, is an ethylene homopolymer or ethylene and propylene, 1-butene,
Copolymers with other α-olefins such as 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, etc., usually having an ethylene density of 0.905 to 0.935 g / cm ³ It is a polymer, and is generally produced and sold as a high pressure method low density polyethylene (HP-LDPE) and linear low density polyethylene (LLDPE), or is obtained in a polymerization system.
The low density polyethylene (b3) usually has a peak temperature (Tp) determined from a crystal melting curve based on DSC in the range of 95 to 125 ° C.
MFR (melt flow rate; ASTM) of low density polyethylene (b3) according to the present invention
D-1238 (load: 2160 g, temperature: 190 ° C.) is not particularly limited as long as the composition mixed with the propylene polymer (b1) and the high density polyethylene (b2) has a film-forming ability. .1-50 g / 10 min, preferably 0.2-35 g / 1
It is in the range of 0 minutes.

[Electrophotographic recording sheet]
The electrophotographic recording sheet of the present invention comprises an inorganic compound powder (a2) and a propylene polymer (a1).
) On one side of a biaxially stretched polypropylene film substrate layer obtained from the propylene polymer composition (A) to which the propylene polymer (b1), high density polyethylene (b2) and low density polyethylene (b3) are added. The surface layer obtained from the ethylene-based polymer composition (B) containing is preferably formed. Preferably, the surface layer has a surface roughness (three-dimensional center plane average roughness; SRa) of 0.
. 2 to 0.6 μm, glossiness of 7 to 60%, and surface resistivity of 1 × 10 ⁷ to 1 × 10 ¹³ Ω
And a biaxially stretched polypropylene laminate film having a light transmittance of 10 to 55% and a density of 0.5 to 0.9 g / cm ³ .

The other side of the biaxially oriented polypropylene film substrate layer of the electrophotographic recording sheet of the present invention (
The surface on which the surface layer obtained from the ethylene-based polymer composition (B) is not formed;
Although it is not particularly limited, the base layer may be used as it is, but it is easy to manufacture a biaxially stretched polypropylene laminated film, easy to handle the resulting biaxially stretched polypropylene laminated film, and used as an electrophotographic recording sheet. It is preferable to form a back layer from the viewpoint of workability when attaching paper or the like to the back surface of the electrophotographic recording sheet. The polymer constituting the back layer is not particularly limited as long as it has a film-forming ability. The propylene polymer (a1) or the ethylene-based polymer composition which is a component constituting the biaxially oriented polypropylene film substrate layer. A thing (B) etc. can be used.

The surface roughness of the surface layer is related to the glossiness, and an electrophotographic recording sheet having a surface roughness of more than 0.6 μm may result in a decrease in toner transfer efficiency and image defects. An electrophotographic recording sheet having a total light transmittance of more than 55% is inferior in concealment, and the back image may be seen through. An electrophotographic recording sheet having a density of less than 0.50 g / cm ³ is extremely unstable in molding, and may be cut during stretching, or the physical properties in the width direction may vary, resulting in a homogeneous electrophotographic recording sheet. On the other hand, an electrophotographic recording sheet having a density of more than 0.90 g / cm ³ may have a reduced resistance to breakage.
As long as the electrophotographic recording sheet of the present invention has at least one surface, that is, a surface layer obtained from the ethylene-based polymer composition (B) on which an image is formed, only the biaxially stretched polypropylene laminated film is configured. However, the structure bonded together with the core material layer by the thickness or the use may be sufficient.

In the electrophotographic recording sheet comprising only the biaxially stretched polypropylene laminated film, the thickness of the base layer is usually 40 to 380 μm, preferably 45 to 280 μm, and the thickness of the surface layer is 0.00.
5 to 50 μm, preferably 2 to 40 μm, when having a back layer, the thickness of the back layer is 0.5
˜50 μm, preferably 1˜40 μm, and the thickness of all layers is 40˜400 μm, preferably 5
It exists in the range of 0-300 micrometers. When the thickness of the surface layer is less than 0.5 μm, the toner adhesion may be reduced. On the other hand, when the thickness of the surface layer is 50 μm or more, there is a risk of sticking on the fixing roll of the printer when used as an electrophotographic recording sheet. On the other hand, if the thickness exceeds 400 μm, the thickness of the obtained electrophotographic recording sheet becomes excessive, resulting in inconveniences such as deterioration in image quality and a decrease in the number of sheets supplied to the paper supply unit of the printer. It becomes.

When the biaxially stretched polypropylene laminated film is used by being bonded to one or both sides of a core material layer such as a paper base material, the thickness of the base material layer is usually 10 to 65 μm, preferably 15 to 5
0 μm, the thickness of the surface layer is 0.5 to 15 μm, preferably 2 to 10 μm, and when having the back layer, the thickness of the back layer is 0.5 to 15 μm, preferably 1 to 10 μm. Say 15
It is in the range of ˜80 μm, preferably 25˜60 μm. If the thickness of all layers is less than 15 μm,
The mechanical and thermal strength becomes insufficient, which may cause sticking due to heat of the fixing roll.
The roughness of the surface layer in the present invention is a three-dimensional surface roughness measuring instrument SE-30KS manufactured by Kosaka Laboratory.
Measured with the analyzer TDA-21 and the average roughness obtained (three-dimensional center plane average roughness SRa)
It is.

In the electrophotographic recording sheet of the present invention, the surface layer obtained from the ethylene-based polymer composition (B) is excellent in water resistance and toner adhesion, and the printing layer has good image quality. Although not necessary, a resin having a high affinity with the toner component such as polyester resin or styrene resin may be applied on the surface layer in order to further improve the toner adhesion, but depending on the type of the coating agent, There is a risk that the performance will be reduced.
Since the recording sheet for electrophotography of the present invention has a surface layer obtained from the ethylene polymer composition (B), the propylene polymer composition (A) which is a biaxially stretched polypropylene film substrate layer is used. Add antistatic agent, surface resistivity of surface layer is 1 × 10 ⁷ to 1 × 10 ¹³ Ω
Preferably, it can be in the range of 1 × 10 ⁸ to 1 × 10 ¹² Ω. When the polymer forming the surface layer is the propylene polymer (b1) alone or the polymer composition obtained by adding the high density polyethylene (b2) to the propylene polymer (b1) is the surface layer, Even if an antistatic agent is added to the surface, the surface resistivity of the surface layer may not be 1 × 10 ¹³ Ω or less.
In the case of an electrophotographic recording sheet having a surface electrical resistance value of less than 1 × 10 ⁷ Ω, when the surface comes into contact with a conductive member such as a fixing roll during toner transfer, the balance of transfer current is lost, resulting in a decrease in toner transfer efficiency. There is a risk of doing. On the other hand, if it exceeds 1 × 10 ¹³ Ω, the electrophotographic recording sheets may be more likely to be double-fed during sheet feeding due to static electricity.
In the electrophotographic recording sheet of the present invention, the surface resistivity of the surface layer is 1 × 10 ⁷ to 1 × 10 ^13.
As long as it is in the range of Ω, it is not necessary to apply an antistatic agent on the surface layer.

As the core material layer used in the electrophotographic recording sheet of the present invention, a high-quality paper mainly composed of cellulose pulp, coated paper, art paper, paper such as cast coated paper, at least one is provided with a thermoplastic resin layer. A paper base material such as processed paper such as laminated paper provided is preferably used. Of these, coated paper and art paper are particularly preferable as the core material layer. With fine paper, the roughness of the paper surface
The high smooth appearance of the surface layer of the biaxially stretched polypropylene laminate film after bonding may be impaired. In cast coated paper, the difference between the front and back of the presence or absence of the cast coated layer may cause curling at the time of fixing. The laminated paper may cause the coating layer and the thermoplastic resin layer to swell and the biaxially stretched polypropylene laminated film to peel off due to the heat history during fixing. It is preferable that the core material layer usually has a thickness of 50 to 200 μm. If the thickness is less than 50 μm, the mechanical strength of the electrophotographic recording sheet laminated with the biaxially stretched polypropylene laminated film becomes insufficient, and the repulsive force against deformation becomes insufficient, and the electrons generated at the time of printing The curling of the photographic recording sheet may not be sufficiently prevented. On the other hand, if the thickness exceeds 200 μm, the thickness of the electrophotographic recording sheet increases and the number of sheets supplied to the paper supply unit of the printer decreases, the deterioration of image quality due to the unevenness of the core material layer, and the texture of the transfer sheet. May be inferior.

The electrophotographic recording sheet of the present invention may be subjected to surface treatment such as corona treatment or flame treatment on one or both sides as necessary. Depending on the application, in order to impart heat sealability, a high pressure process low density polyethylene, linear low density polyethylene, a random copolymer of crystalline or low crystalline ethylene and an α-olefin having 3 to 10 carbon atoms, or Random copolymer of propylene and ethylene or α-olefin having 4 or more carbon atoms, polybutene, ethylene
You may laminate | stack the film which consists of low melting point polymers, such as a vinyl acetate copolymer, alone or those compositions on a back surface layer. Furthermore, in order to improve adhesiveness with other substances, the surface of the stretched film may be anchored with an adhesive such as imine or urethane, or maleic anhydride-modified polyolefin may be laminated.

<Method for producing electrophotographic recording sheet>
The electrophotographic recording sheet of the present invention has, for example, a propylene polymer composition (A
), A multilayer sheet obtained by coextrusion molding of the ethylene polymer composition (B) to be the surface layer and, if necessary, the polymer to be the back layer by a method known per se, a simultaneous biaxial stretching method Or it is usually 45 by a surface magnification (longitudinal direction x transverse direction) by a biaxially stretched film forming method such as a sequential biaxial stretching method
It can be obtained by stretching to 65 times, preferably 50 to 60 times.
When the surface magnification is less than 45 times, the rigidity and heat resistance of the biaxially stretched polypropylene film base material layer are not improved, and the recording sheet may shrink due to heat when used as an electrophotographic recording sheet.
On the other hand, an electrophotographic recording sheet having a surface magnification exceeding 65 times may cause the film to be cut during stretching, and a stable quality electrophotographic recording sheet may not be obtained.

A specific example in the case of producing the electrophotographic recording sheet forming method of the present invention by sequential biaxial stretching will be described in the longitudinal direction at a temperature of 70 to 140 ° C, preferably 90 to 120 ° C, 4.5 to 7
. After stretching in the range of 5 times, preferably 5 to 7 times, then in the transverse direction 120 to 190 ° C., preferably 140 to 180 ° C., 7 to 12 times, preferably 8 to 11 times and surface magnification (
(Longitudinal direction × transverse direction) after stretching to 45 to 65 times, preferably 50 to 60 times, 110 to 18
It can be obtained by heat setting in a temperature range of 0 ° C., preferably 125 to 170 ° C.
If the stretching temperature in the machine direction is less than 70 ° C, the multilayer sheet may not be stretched uniformly. On the other hand, if it exceeds 140 ° C, it may be difficult to form voids in the film. Further, if the stretching ratio in the longitudinal direction is less than 4.5 times, the multilayer sheet may not be uniformly stretched, and if it exceeds 7.5 times, the film formability may be deteriorated.
If the transverse stretching temperature is less than 120 ° C., the multilayer sheet may not be uniformly stretched.
When it exceeds 90 degreeC, there exists a possibility that it may be difficult to form a space | gap in a film. In addition, if the stretching ratio in the transverse direction is less than 7 times, the multilayer sheet may not be uniformly stretched, and if it exceeds 12 times, the film formability may be deteriorated.

Further, if the heat setting temperature is less than 110 ° C., curling may occur in the electrophotographic recording sheet and the processability may be lowered, and if it exceeds 180 ° C., it may be difficult to form voids in the film.
In order to obtain an electrophotographic recording sheet having a core material layer, the biaxially stretched polypropylene laminated film and the core material can be bonded together by various known methods. The method of laminating (adhering and laminating) the biaxially stretched polypropylene laminated film on one side or both sides of the core material layer is not particularly limited, but includes a wet laminating method, an extrusion laminating method,
Known techniques such as a dry laminating method and a wax laminating method are used. In general, the dry laminating method is widely used, and as the polymer resin used at this time, a polyisocyanate-based or epoxy-based curing agent is added to a polyether-based or polyester-based polymer adhesive component. Are often used. The coating amount of the adhesive is 1-30 g /
The range of m ² is desirable, and in order to maintain the curl balance, it is preferable that the coating amount of the adhesive on the front surface layer and the back surface layer of the core material layer be the same. An extrusion laminating method is also preferably used for improving the image quality. The thickness of an electrophotographic recording sheet having a core layer is usually
It is preferable that it exists in the range of 100-500 micrometers.

EXAMPLES Next, although an Example is given and this invention is demonstrated further more concretely, this invention is not restrict | limited to these Examples, unless the technical idea is exceeded. In this example, unless otherwise specified, “%” and “parts” mean “% by mass” and “parts by mass”, except for those relating to solvents.

<Evaluation of physical properties>
The physical property values in Examples and Comparative Examples are values obtained by the following evaluation methods.
(1) Haze (%)
The light transmittance of one biaxially stretched laminated polypropylene film was measured according to JIS K 7105 using Haze Meter (NDH-300A manufactured by Nippon Denshoku Industries Co., Ltd.).
(2) Light transmittance (%)
The light transmittance of one biaxially stretched laminated polypropylene film was measured according to JIS K 7105 using Haze Meter (NDH-300A manufactured by Nippon Denshoku Industries Co., Ltd.).
(3) Glossiness (%)
Using a Haze Meter (Nippon Denshoku Industries Co., Ltd. VGS-1D-300A), the measurement was performed according to JIS K 7105 at an incident angle of 60 °.
(4) Surface roughness (μm)
Three-dimensional center surface average roughness SRa was measured using a three-dimensional surface roughness measuring instrument (SE-30KS manufactured by Kosaka Laboratory) and an analyzer (TDA-21 manufactured by Kosaka Laboratory).
(5) Density (g / cm ³ )
It was calculated by measuring the mass thickness and 1 m ² per film.
(6) Surface resistivity (Ω)
Advantest Digital Ultra High Resistance / Micro Ammeter R8340A, Resistivity
It measured according to JISK6911 using chamber R12704.
(7) Color tone (-)
Overlay 10 sheets of biaxially stretched polypropylene laminated film on white paper, Spectro
The L * value was measured using Eye (manufactured by Gretag Macbeth).
(8) Melting peak temperature (° C)
About 5 mg of polymer was weighed and a differential scanning calorimeter (DSC Q1 manufactured by TA Instruments) was used.
00), the temperature was raised to 240 ° C. at 10 ° C./min, held at 240 ° C. for 5 minutes, then cooled down to −50 ° C. at 10 ° C./min, and the temperature was raised again. Rate: -5 at 10 ° C / min
The melting curve when the temperature was raised to 0 ° C. to 240 ° C. was measured, and the peak temperature (
Tp) was determined.
(9) Suitability for electrophotography [Evaluation of recordability of electrophotographic recording sheet]
After the electrophotographic recording sheet is stored at 23 ° C. and 50% RH for 10 hours, an ISO standard image “name: N3A fruit basket” is output using a color laser printer LBP2410 (manufactured by Canon Inc.) in A4 size. In addition, running performance, image quality reproducibility, and cracking were evaluated by the following methods.
(I) Running performance ○: 10 sheets printed continuously, no paper jam ×: 10 sheets printed continuously, double feed or paper jam occurred (b) Image quality reproducibility ○: Original image reproducibility is good ×: Original image is not reproduced due to poor toner transfer (c) Fracture resistance Once the crease is made so that the image receiving surface is convex, then the crease is opened, and the toner is rubbed with a finger along the crease. Observe for delamination.
○: No toner layer peeling ×: Toner layer peeling (10) Water resistance 1 ml of water is dropped on the image receiving surface, and after 1 minute, the wet part is rubbed with a finger. The degree of toner peeling was visually evaluated according to the following evaluation criteria.
○: There is no toner peeling.
X: Toner peeling off.

Example 1
<Base material layer: Propylene polymer composition (A) layer>
Propylene homopolymer (a 1-1): Propylene homopolymer (PP-1; melting point: 162)
C., MFR: 2.0 g / 10 min), tetrakis [methylene-3- (
3 ', 5'-di-t-butyl-4'hydroxyphenyl) propionate] methane (Nippon Ciba Geigy product name "Irganox 1010") 1000 ppm and calcium stearate (Nippon Yushi) 1000 ppm added propylene homopolymer .
Calcium carbonate powder [average particle size: 1.2 μm, maximum particle size: 5 μm, 90% cumulative frequency particle size of 2 is added to the propylene homopolymer (a1-1) and the propylene homopolymer (a1-1). 0.5 μm, moisture content: 400 ppm or less (Karl Fischer method, measured at 200 ° C.)
] Is dry blended to obtain a propylene homopolymer (
a propylene polymer composition (A1-1) containing 97.2% a1-1) and 2.8% calcium carbonate
-1) was prepared. The propylene polymer composition includes a propylene polymer composition 100.
8500 ppm of a mixture of antistatic agents mainly composed of alkyldiethanolamine fatty acid ester as an antistatic agent was added to parts by mass.
<Surface layer and back layer: ethylene polymer composition (B) layer>
Propylene homopolymer component (b1-1-1; MFR: 20 g / 10 min, Tp: 160 ° C.
): 40%, propylene / ethylene / 1-butene random copolymer component (b1-2-1;
MFR: 7 g / 10 min, Tp: 139.7 ° C.): 20%, high-density polyethylene component (b2
−1; MFR: 0.33 g / 10 min, density: 0.964 g / cm ³ , Tp: 128.1 ° C.
): 10% and high pressure method low density polyethylene component (b3-1; MFR: 0.35 g / 10 min, density: 0.919 g / cm ³ , Tp: 109.8 ° C.): 30%, heat stabilizer As tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-4′hydroxyphenyl) propionate] methane (product name “Irganox 10” manufactured by Ciba Geigy Japan)
10 ") ethylene polymer composition (B-1) containing 1000 ppm and calcium stearate (manufactured by NOF Corporation) 1000 ppm (Tp: 109.8 ° C, 128.1 ° C and 156.
8 ° C., MFR: 4.5 g / 10 min).
<Manufacture of biaxially oriented polypropylene laminated film>
The ethylene polymer composition (B-1) as the surface layer and the back surface layer, and the propylene polymer composition (A-1) as the base material layer, the extrusion ratio of the surface layer / base material layer / back surface layer (1 / 12 / 1.5)
Each was melted using a screw extruder, extruded using a multi-manifold type T-die, and rapidly cooled on a cooling roll to obtain a multilayer sheet having a thickness of about 1.5 mm. This sheet was heated at 110 ° C. and stretched 5.0 times in the film flow direction (longitudinal direction). This 5.
The sheet stretched 0 times is heated at 160 ° C. and 1 in the direction perpendicular to the flow direction (lateral direction).
Stretched 0 times (surface magnification: 50 times), substrate layer thickness: 29 μm, surface layer thickness: 3.6 μm
And the thickness of the back layer: 2.4 micrometers (total thickness: 35 micrometers) The biaxially stretched polypropylene laminated film was obtained. The front layer and the back layer of the biaxially stretched polypropylene laminated film were subjected to corona treatment. The physical properties and the like of the obtained biaxially stretched polypropylene laminated film were measured by the method described above.
Next, the obtained biaxially stretched polypropylene laminated film was made of high-quality paper (OK) having a thickness of 67 μm.
Polyurethane adhesive (trademark: AD-) on both sides of high-quality paper 52.3g / m ² , made by Oji Paper Co., Ltd.
593, manufactured by Toyo Morton Co., Ltd.), and bonded together at a coating amount of 5 g / m ² as an adhesive amount to obtain an electrophotographic recording sheet. Table 1 shows the evaluation results obtained by measuring the physical properties and the like of the obtained electrophotographic recording sheet by the method described above.

Example 2
As the propylene polymer composition for the base material layer, the propylene homopolymer used in Example 1 (
a1-1) and the calcium carbonate composition and the propylene homopolymer used in Example 1 (a
1-1) Rutile-type titanium oxide treated with alumina [average particle size: 0.2 μm, water content:
400 ppm or less (Karl Fischer method, measured at 200 ° C.) kneaded to dry blend, 92.7% propylene homopolymer (a1-1), 3.0% calcium carbonate and titanium oxide Except that the extrusion ratio of the surface layer / base material layer / back surface layer is (2 / 31.5 / 1.5) using a propylene polymer composition (A-2) containing 4.3% of In the same manner as in Example 1, the thickness of the base layer is 31.5 μm, the thickness of the surface layer is 2.0 μm, and the thickness of the back layer is 1.5 μm (total thickness: 35 μm). An electrophotographic recording sheet bonded to a polypropylene film and fine paper was obtained.
The evaluation results are shown in Table 1.

Example 3
Instead of the propylene polymer composition (A-1) used in Example 1 as the propylene polymer composition for the base material layer, 94.0% of the propylene homopolymer (a1-1) and calcium carbonate were used. The propylene polymer composition (A-3) containing 3.0% and 3.0% titanium oxide was used, and the ethylene polymer composition (B-1) used in Example 1 was used as the polymer for the back layer. Instead of
Using a propylene homopolymer (PP-1; MFR: 3 g / 10 min, Tp: 158 ° C.), the extrusion ratio of the surface layer / base material layer / back surface layer was (0.5 / 5.1 / 0.4). Except to be
Biaxially stretched laminated polypropylene having the same base layer thickness: 25.5 μm, surface layer thickness: 2.5 μm, and back layer thickness: 2.0 μm (total thickness: 30 μm) as in Example 1. An electrophotographic recording sheet bonded to the film and fine paper was obtained.
The evaluation results are shown in Table 1.

Example 4
As a propylene polymer composition for a base material layer, instead of the propylene polymer composition (A-1) used in Example 1, 84.1% of a propylene homopolymer (a1-1) and calcium carbonate were used. Using a propylene polymer composition (A-4) containing 11.5% and 4.4% titanium oxide,
As a polymer for the back layer, a propylene homopolymer (PP-1; MFR: 3 g / 10 min, Tp: 158 ° C.) was used instead of the ethylene-based polymer composition (B-1) used in Example 1. Use
The same procedure as in Example 1 was conducted except that the extrusion ratio of the front surface layer / base material layer / back surface layer was (1.1 / 14.5 / 1.1). A biaxially stretched laminated polypropylene film of 7 μm, surface layer thickness: 1.65 μm, and back layer thickness: 1.65 μm (total thickness: 25 μm) and an electrophotographic recording sheet bonded to fine paper were obtained. .
The evaluation results are shown in Table 1.

Example 5
Instead of the propylene polymer composition (A-1) used in Example 1 as the propylene polymer composition for the base material layer, 83.8% of the propylene homopolymer (a1-1) and calcium carbonate were used. Using a propylene polymer composition (A-5) containing 12.0% and 4.2% titanium oxide,
As the polymer for the surface layer, a composition obtained by adding 3% of the calcium carbonate powder used in Example 1 to the ethylene-based polymer composition (B-1) used in Example 1 is used. As the polymer for the back layer used, instead of the ethylene-based polymer composition (B-1) used in Example 1, a propylene homopolymer (PP-1; MFR: 3 g / 10 min, Tp: 158) 1), and the extrusion ratio of the front surface layer / base material layer / back surface layer is (1.5 / 10/1).
The thickness of the base layer: 20 μm, the thickness of the surface layer: 3.0 μm, and the thickness of the back layer: 2
. An electrophotographic recording sheet bonded to a 0 μm (total thickness: 25 μm) biaxially stretched laminated polypropylene film and fine paper was obtained.
The evaluation results are shown in Table 1.

Example 6
Instead of the propylene polymer composition (A-1) used in Example 1 as the propylene polymer composition for the base material layer, 75.0% of the propylene homopolymer (a1-1) and calcium carbonate were used. Using a propylene polymer composition (A-6) containing 20.0% and titanium oxide 5.0%,
As a polymer for the back layer, a propylene homopolymer (PP-1; MFR: 3 g / 10 min, Tp: 158 ° C.) was used instead of the ethylene-based polymer composition (B-1) used in Example 1. Use
Example 1 except that the extrusion ratio of the surface layer / base material layer / back surface layer is (8/17/8).
And a biaxially stretched laminated polypropylene film having a base layer thickness of 77.2 μm, a surface layer thickness of 36.4 μm, and a back layer thickness of 36.4 μm (total thickness: 150 μm). An electrophotographic recording sheet was obtained.
The evaluation results are shown in Table 1.

Comparative Example 1
Instead of the propylene polymer composition (A-1) used in Example 1 as the propylene polymer composition for the base material layer, 86.8% of the propylene homopolymer (a1-1) and calcium carbonate were used. Using the propylene polymer composition (A-6) containing 6.0% and titanium oxide 7.2%, the ethylene-based polymer composition used in Example 1 as a polymer for the front surface layer and the back surface layer ( B-1)
Instead of propylene homopolymer (PP-1; MFR: 3 g / 10 min, Tp: 158 ° C.)
Except that the extrusion ratio of the front surface layer / base material layer / back surface layer is (1/18/1).
Biaxially stretched laminated polypropylene having a base layer thickness of 27.0 μm, a surface layer thickness of 1.5 μm and a back layer thickness of 1.5 μm (total thickness: 30 μm) An electrophotographic recording sheet bonded to the film and fine paper was obtained.
The evaluation results are shown in Table 1.

Comparative Example 2
Instead of the propylene polymer composition (A-1) used in Example 1 as the propylene polymer composition for the base material layer, 88.0% of the propylene homopolymer (a1-1) and calcium carbonate were used. Using the propylene polymer composition (A-7) containing 6.0% and 6.0% titanium oxide, the ethylene polymer composition (B-1) used in Example 1 was used as the surface layer polymer. Instead of
Propylene homopolymer component (b1-1-2; Tp: 160 ° C.): 40%, propylene / ethylene random copolymer component (b1-2-2; Tp: 135.3 ° C.): 30% and low density polyethylene Component (b3-2; density: 0.919 g / cm ³ , Tp: 109.8 ° C.): 3
Polymer composition comprising 0% (C-1; Tp: 109.0 ° C., 144.3 ° C. and 152.5 ° C.
In place of the ethylene-based polymer composition (B-1) used in Example 1 as a polymer for the back surface layer, and a propylene homopolymer (CFR, MFR: 5.0 g / 10 min). PP-1; M
FR: 3 g / 10 min, Tp: 158 ° C.) and the extrusion ratio of the surface layer / base material layer / back surface layer is (1
. 5 / 12.5 / 1), except that the thickness of the base material layer is 2 as in Example 1.
5.0 μm, surface layer thickness: 3.0 μm, and back layer thickness: 2.0 μm (total thickness: 30
An electrophotographic recording sheet bonded to a (μm) biaxially stretched laminated polypropylene film and fine paper was obtained.
The evaluation results are shown in Table 1.

Comparative Example 3
Instead of the propylene polymer composition (A-1) used in Example 1 as the propylene polymer composition for the base material layer, 83.8% of the propylene homopolymer (a1-1) and calcium carbonate were used. Using a propylene polymer composition (A-8) containing 12.0% and 4.2% titanium oxide,
As a polymer for the surface layer, instead of the ethylene-based polymer composition (B-1) used in Example 1, a propylene homopolymer component (PP-1; MFR: 3 g / 10 min, Tp: 158 ° C. 9)
6.5% and high density polyethylene component (b2-2; MFR: 5.2 g / 10 min, density: 0)
. An ethylene-based polymer composition containing 3.5% of 968 g / cm ³ and Tp: 134.9 ° C.) was used, and as the polymer for the back layer, the ethylene-based polymer composition used in Example 1 ( B-1
), Propylene homopolymer (PP-1; MFR: 3 g / 10 min, Tp: 158 ° C.
), And the extrusion ratio of the surface layer / base material layer / back surface layer is set to (1.5 / 10/1). A biaxially stretched laminated polypropylene film of 0 μm, surface layer thickness: 3.0 μm, and back layer thickness: 2.0 μm (total thickness: 25 μm) and an electrophotographic recording sheet bonded to fine paper were obtained. .
The evaluation results are shown in Table 1.

表１の記載から明らかなように、プロピレン系重合体（ｂ１）、高密度ポリエチレン（
ｂ２）及び低密度ポリエチレン（ｂ３）を含むエチレン系重合体組成物（Ｂ）から得られ
る表面層を有する二軸延伸ポリプロピレン積層フィルムからなることを特徴とする電子写
真用記録シート（実施例１〜６）は、隠蔽性を有し、表面層の光沢度が低く、表面粗さも
良好で、且つ表面固有抵抗値も１×１０¹³Ω以下を示し、走行性、画質再現性及び耐折り
割れ性に優れ、耐水性も良好である。また、二軸延伸ポリプロピレンフィルム基材層を構
成するプロピレン重合体組成物（Ａ）として、炭酸カルシウム粉末と酸化チタン粉末を添
加した組成物を用いた電子写真用記録シート（実施例２〜６）は、さらに隠蔽性が良好で
、光沢度も低く、且つ白色度に優れている。
一方、表面層がプロピレン系重合体のみからなる電子写真用記録シート（比較例１）、
プロピレン系重合体と低密度ポリエチレンからなる表面層を有する電子写真用記録シート
（比較例２）及びプロピレン系重合体と高密度ポリエチレンからなる表面層を有する電子
写真用記録シート（比較例３）は、何れも、耐折り割れ性に劣っている。さらに、プロピ
レン系重合体のみからなる表面層を有する電子写真用記録シート（比較例１）及びプロピ
レン系重合体と高密度ポリエチレンからなる表面層を有する電子写真用記録シート（比較
例３）は、光沢度が高く、且つ帯電防止剤を基材層に添加しても表面固有抵抗値が１．８
〜２．７×１０¹⁵Ωと走行性や画質再現性にも劣ることが明らかである。

As is apparent from the description in Table 1, the propylene polymer (b1), high density polyethylene (
An electrophotographic recording sheet comprising a biaxially stretched polypropylene laminated film having a surface layer obtained from an ethylene polymer composition (B) containing b2) and low density polyethylene (b3) (Examples 1 to 3) 6) has concealability, low glossiness of the surface layer, good surface roughness, and surface resistivity of 1 × 10 ¹³ Ω or less, running property, image quality reproducibility and anti-cracking property Excellent water resistance. Moreover, the recording sheet for electrophotography using the composition which added the calcium carbonate powder and the titanium oxide powder as a propylene polymer composition (A) which comprises a biaxially-stretched polypropylene film base material layer (Examples 2-6) Has better concealability, low gloss and excellent whiteness.
On the other hand, an electrophotographic recording sheet (Comparative Example 1) whose surface layer is composed only of a propylene polymer,
An electrophotographic recording sheet having a surface layer composed of a propylene polymer and low density polyethylene (Comparative Example 2) and an electrophotographic recording sheet having a surface layer composed of a propylene polymer and high density polyethylene (Comparative Example 3) , Both are inferior in crack resistance. Furthermore, an electrophotographic recording sheet (Comparative Example 1) having a surface layer composed only of a propylene polymer and an electrophotographic recording sheet (Comparative Example 3) having a surface layer composed of a propylene polymer and high-density polyethylene are: Glossiness is high, and even if an antistatic agent is added to the base material layer, the surface resistivity is 1.8.
It is apparent that the running performance and image quality reproducibility are inferior to 2.7 × 10 ¹⁵ Ω.

The electrophotographic recording sheet of the present invention is extremely useful as a sheet for recording by a recording method using an electrophotographic method. In addition, the electrophotographic recording sheet of the present invention is not limited to paper for electrophotographic printers in particular, and can be effectively applied to letterpress printing, gravure printing, flexographic printing, solvent offset printing, ultraviolet curable offset printing, and the like. it can. In addition, the electrophotographic recording sheet of the present invention can be applied to printing of a recording form as it is and printing of a roll-type rotary system.
The printed matter printed on the electrophotographic recording sheet of the present invention is excellent in water resistance, taking advantage of such characteristics, outdoor, frozen food related advertising posters, signs, signs, tags, usage instructions and precautions It can be used for manufacturing management cards with written notes.

Claims (6)

On one side of a biaxially stretched polypropylene film substrate layer obtained from the propylene polymer composition (A) obtained by adding the inorganic compound powder (a2) to the propylene polymer (a1), the propylene polymer (b1), high An electrophotographic recording sheet comprising a biaxially stretched polypropylene laminated film on which a surface layer obtained from an ethylene polymer composition (B) containing high density polyethylene (b2) and low density polyethylene (b3) is formed . The biaxially stretched polypropylene laminated film has a surface layer surface roughness (three-dimensional center plane average roughness;
SRa) is in the range of 0.2 to 0.6 μm and the glossiness is in the range of 7 to 60%, and the light transmittance of the biaxially oriented polypropylene laminated film is 10 to 55% and the density is 0.50 to 0.90 g /
The electrophotographic recording sheet according to claim 1, which is in a range of cm ³ . The ethylene polymer composition (B) is 85 to 50% by mass of the propylene polymer (b1),
The high density polyethylene (b2) is 3 to 30% by mass and the low density polyethylene (b3) is 10 to 10%.
2. The electrophotographic recording sheet according to claim 1, which is a composition containing 45% by mass (b1 + b2 + b3 = 100% by mass). The propylene polymer (b1) is a propylene homopolymer (b1-1) and propylene / α.
The recording sheet for electrophotography according to claim 1 or 3, comprising an olefin random copolymer (b1-2). The propylene polymer composition (A) is composed of 55 to 92% by mass of the propylene polymer (a1), calcium carbonate having an average particle size of 0.5 to 5 μm, and an 80% cumulative frequency particle size of 3 to 3 μm.
2. The electrophotographic recording sheet according to claim 1, wherein the electrophotographic recording sheet is a composition with an inorganic compound powder (a2) comprising 0% by mass and 1 to 10% by mass of titanium oxide. An electrophotographic recording sheet comprising the biaxially stretched polypropylene laminated film according to any one of claims 1 to 5 bonded to at least one surface of a paper substrate.