JPH11268402A - Recording sheet and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording sheet (in particular, a jet recording sheet) having a good printing property, transparency, and preservability, and also having an antistatic property, and manufacture thereof. SOLUTION: The recording sheet is formed having a layer containing as an antistatic agent polythiophene consisting of a repetition unit shown by formula (in the formula, R<1> , R<2> express respectively hydrogen or a 1-4C alkyl group independently, or form a 1-4C substitutive alkylene group together). Coating liquid consisting of dissolving or dispersing this polythiophene is applied on a base material sheet directly or via another layer to subsequently be dried, so that a layer can be formed having an antistatic property.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for directly printing out visually recognizable information such as characters and images on the basis of electrical or optical recording signals without using a printing plate. The present invention relates to a recording sheet, and more particularly to a recording sheet used for an ink jet printer.

[0002]

2. Description of the Related Art Visual information such as characters and images created by a computer or a word processor can be recorded in a wire dot recording system, a thermosensitive coloring recording system, a heat-sensitive melt transfer recording system, a thermosensitive sublimation transfer recording system, an electrophotographic recording system, Printed out by various methods such as an ink jet recording method. Among them, the ink jet recording method has the features that plain paper can be used as recording paper, that printing cost is low, that the apparatus is compact, that there is no noise, and that high-speed recording is possible. For this reason, inkjet recording type printers are often
Attention has been drawn to a printer capable of rapidly and accurately outputting visual information such as characters, symbols, figures, and images created by the A-device, and development is being promoted. Also,
The ink jet recording method is easy to colorize, and the finished pattern is clear. For this reason, there is an increasing demand that image information created by a computer or the like be recorded on a transparent recording sheet by an ink jet printer and used as a manuscript of an OHP or the like in a conference or presentation at various conferences.

In general, in an ink jet printer, recording ink is ejected from nozzles by the pressure of a fine piezoelectric element (piezo element) or the pressure of air (bubble jet) generated by heating a thermal head. Recording is performed by adhering to a sheet for use. Ink for inkjet printers
Usually, it is prepared by dissolving dyes, resins, additives, etc. in a mixed solvent of water and alcohol, but if it is too easy to dry, it will dry at the tip of the nozzle and increase in viscosity, causing jetting failure and This causes nozzle clogging. For this reason, inks that are difficult to dry are used in inkjet printers.

[0004] However, if the ink is difficult to dry,
Since the drying time after spraying the ink on the recording sheet becomes longer, it becomes difficult to reduce the required printing time to a certain level or more, and it also causes blurring of characters and images. Become. For this reason, a recording sheet used for printing out with an inkjet printer may absorb liquid components in the ink when the hard-to-dry ink is sprayed, and may be capable of rapidly drying and solidifying the ink. Desired. In order to satisfy this requirement, an ink jet recording sheet provided with an ink receiving layer having excellent ink absorbency on an image receiving surface is used.

[0005] The ink receiving layer of the ink jet recording sheet is required to have the following characteristics. (1) It is excellent in ink absorbency and can dry the ink quickly, and (2) It is excellent in image quality, that is, the deposited ink spreads appropriately and forms dots of an appropriate size. (3) that a clear image without blurs can be obtained;
When used in OHP, haze is not large, transparency is high, and (4) storage stability is excellent, that is, printability is deteriorated even after the inkjet recording sheet is stored in a high-temperature and high-humidity environment. It does not cause blocking, (5) it has curl resistance, that is, it does not cause curling of the ink jet recording sheet in a use environment, and (6) it does not cause adhesion of dust due to electrification or double feeding of the sheet.

[0006] In order to satisfy these demands, the development of an ink jet recording sheet has been promoted. At present, a recording sheet formed by forming an ink receiving layer on a base material with a water-absorbing resin or a water-soluble resin, or the like. Has been put to practical use.

[0007]

However, an ink receiving layer made of a water-soluble resin such as polyvinyl alcohol or polyvinylpyrrolidone or a water-absorbing resin such as a water-absorbing polyester resin has a chargeability. It is easy to be charged in a low humidity environment at normal temperature. For this reason, there is a problem of adhesion of dust due to static electricity and a problem in conveyance such as double feeding during printing. In particular, the adhesion of dust leads to a reduction in image quality and resolution of a formed image, and causes a problem that an image quality that can be used practically cannot be obtained.

As a method for solving such a problem, it is known to form an antistatic layer containing a surfactant or other components as an antistatic agent on the back surface of the recording sheet. However, when a conventional antistatic layer containing an antistatic agent is formed on a recording sheet, there are problems that the sheet becomes sticky and the haze increases. Further, when the recording sheets are stacked and stored, the antistatic agent in the antistatic layer migrates to the adjacent ink receiving layer, causing ink bleeding and deterioration in printability. Furthermore, even if the antistatic effect is not sufficient from the beginning, or even if the antistatic effect is sufficient in the initial stage, the antistatic agent migrates to various places where it comes into contact with the antistatic layer during storage of the recording sheet. Thus, there is a problem that the antistatic effect decreases with time.

The present invention has been accomplished in view of the above circumstances, and has excellent printability, transparency, and storage stability, and also has excellent antistatic properties, particularly an ink-jet recording sheet and its preferred ink-jet recording sheets. It is intended to provide a simple manufacturing method.

[0010]

In order to solve the above-mentioned problems, in the present invention, the following formula (1) is used as an antistatic agent.

Embedded image [In the formula (1), R ¹ and R ² each independently represent hydrogen or an alkyl group having 1 to 4 carbon atoms, or have 1 to 4 carbon atoms which may be substituted together. Form an alkylene group. A recording sheet for recording characters, images and / or other visually recognizable information, characterized by having a layer containing a polythiophene comprising a repeating unit represented by the following formula:

The polythiophene used in the present invention is an electron conductive antistatic agent and unlike the conventional ion conductive antistatic agent, is less susceptible to environmental humidity. Demonstrates prevention performance.
In addition, such polythiophene is a polymer and unlike conventional low molecular weight antistatic agents, it is difficult to bleed out from the antistatic layer, so the antistatic performance is reduced, the recording sheet is sticky, and the receiving layer due to the bleedout antistatic agent is formed. Almost no contamination (set-off). Furthermore, such polythiophenes are highly transparent.

Therefore, by using such a polythiophene as an antistatic agent for a recording sheet, excellent antistatic properties can be imparted without impairing the printability, transparency and storage stability of the recording sheet.

[0013] Among the recording sheets, an ink jet recording sheet is provided with an ink receiving layer containing a water-soluble resin, and this ink receiving layer is easily charged. Therefore, it is extremely effective to add the above polythiophene to the ink receiving layer of the ink jet recording sheet or other layers.

Accordingly, the present invention provides an ink jet recording sheet comprising at least a base sheet and an ink receiving layer mainly composed of a water-soluble resin and / or a water-based resin provided on the base sheet. Accordingly, there is provided a recording sheet containing a polythiophene in which at least one of the ink receiving layer and the other layer comprises a repeating unit represented by the formula (1).

In a preferred method of manufacturing a recording sheet according to the present invention, a coating solution obtained by dissolving or dispersing the above-described polythiophene as an antistatic agent is applied onto a base material sheet directly or via another layer. And drying to form a layer having antistatic properties.

The above polythiophene can be prepared from water or a water- and water-miscible organic solvent (eg, methanol, ethanol,
In a mixed solvent of acetone or the like) in the presence of a polyanion and partially dissolved or dispersed with a positive charge. Therefore,
A polythiophene-containing layer is easily formed by preparing a coating solution such as an antistatic layer coating solution or a receiving layer coating solution containing the polythiophene and applying the coating solution on a recording sheet base sheet. can do.

[0017]

Next, the present invention will be described in more detail with reference to specific examples of an ink jet recording sheet.
Note that the recording sheet according to the present invention is used for directly printing out visually recognizable information such as characters and images based on electrical or optical recording signals without using a printing plate. It covers all recording sheets, and is not limited to inkjet recording sheets.

FIG. 1, FIG. 2 and FIG. 3 are diagrams schematically showing the cross sections of the ink jet recording sheets 1A, 1B and 1C according to the present invention, respectively.

The ink jet recording sheet (1) shown in FIG.
In A), an ink-receiving layer 3 capable of forming an image is provided on one surface of a base sheet 2. In the ink receiving layer 3, the following formula (1) is used as an antistatic agent.

Embedded image [In the formula (1), R ¹ and R ² each independently represent hydrogen or an alkyl group having 1 to 4 carbon atoms, or have 1 to 4 carbon atoms which may be substituted together. Form an alkylene group. And a polythiophene comprising a repeating unit represented by the formula: Polythiophene is
It may be uniformly distributed in the ink receiving layer, or may be unevenly distributed in the portion 3b near the surface of the ink receiving layer as shown in FIG. In FIG. 1, the lower portion 3a of the ink receiving layer does not contain polythiophene.

An anti-curl / antistatic layer 4 for the purpose of preventing curl and antistatic is provided on the surface of the base sheet 2 opposite to the surface on which the ink receiving layer 3 is formed. The anti-curl / antistatic layer 4 contains polythiophene comprising a repeating unit represented by the formula (1) or other antistatic agents.

The ink jet recording sheet (1) shown in FIG.
In B), the ink receiving layer 3 is provided on one surface of the base sheet 2, and the antistatic layer 5 containing polythiophene composed of the repeating unit represented by the formula (1) is further provided thereon. . The ink receiving layer 3 of the ink jet recording sheet (1B) does not contain polythiophene. On the other surface of the base sheet 2, a curl prevention / antistatic layer 4 similar to that shown in FIG. 1 is provided.

The ink jet recording sheet (1) shown in FIG.
In C), the ink receiving layer 3 is provided on one surface of the base sheet 2 via the primer layer 6, and the curl prevention / antistatic layer similar to that shown in FIG. 1 is provided on the other surface. 4 are provided. The primer layer 6 contains polythiophene composed of a repeating unit represented by the formula (1) as an antistatic agent. Further, the ink receiving layer 3 of the ink jet recording sheet (1C) does not contain polythiophene.

The recording sheet according to the present invention has at least one layer containing a polythiophene composed of a repeating unit represented by the following formula (1) as an antistatic agent. The layer containing polythiophene may be a dedicated antistatic layer, or may also serve as a receiving layer, a primer layer, and an anti-curl layer.

[0024]

Embedded image In the formula (1), R ¹ and R ² each independently represent hydrogen or an alkyl group having 1 to 4 carbon atoms, or
Together, they form an optionally substituted alkylene group having 1 to 4 carbon atoms.

Examples of the alkyl group having 1 to 4 carbon atoms include a methyl group and an ethyl group.

The alkylene group having 1 to 4 carbon atoms includes, for example, methylene which may be substituted with alkyl; 1,2-ethylene which may be substituted by an alkyl group having 1 to 12 carbon atoms or a phenyl group, respectively. 1,3-propylene; 1,2-cyclohexylene; 2,3-butylene;
2,3-dimethyl-2,3-butylene; 2,3-pentylene and the like. 1,2-alkylene groups such as 1,2-ethylene include ethene, prop-1-ene,
It can be derived from α-olefins such as hex-1-ene, oct-1-ene, des-1-ene and dodes-1-ene or 1,2-dibromoalkane obtained by brominating styrene. Among the alkylene groups, methylene, 1,2-ethylene and 1,3-propylene are preferred, and 1,2-ethylene is particularly preferred.

Polythiophene comprising a repeating unit represented by the formula (1) is an electron conductive antistatic agent, and unlike a conventional ion conductive antistatic agent, is less susceptible to environmental humidity. Also exhibit sufficient antistatic performance. In addition, such polythiophene is a polymer and unlike conventional low molecular weight antistatic agents, it is difficult to bleed out from the antistatic layer, so the antistatic performance is reduced, the recording sheet is sticky, and the receiving layer due to the bleedout antistatic agent is formed. Almost no contamination (set-off). Therefore, excellent printability and storage stability are provided. Further, since such polythiophene has high transparency, it can be used for a recording sheet for OHP.

The above polythiophene can be prepared from water or an organic solvent miscible with water (eg, methanol, ethanol,
In a mixed solvent of acetone or the like) in the presence of a polyanion and partially dissolved or dispersed with a positive charge. Therefore,
A polythiophene-containing layer is easily formed by preparing a coating solution such as an antistatic layer coating solution or a receiving layer coating solution containing the polythiophene and applying the coating solution on a recording sheet base sheet. can do.

As a source of the polyanion, for example,
Polymer sulfonic acid such as polystyrene sulfonic acid, polymer carboxylic acid such as polyacrylic acid, polyphosphoric acid,
Alternatively, their alkali salts, especially those having a molecular weight of 2,000
Those having 0 to 500,000 can be used. A preferred polyanion is polystyrene sulfonic acid. When preparing a dispersion, the average particle size of the polythiophene in such a dispersion is preferably 10 μm or less. The polythiophene solution or dispersion can be obtained as a commercial product, for example, from Bayer under the trade name “Baytron P”.

The coating liquid for forming the polythiophene-containing layer may be prepared by adding polythiophene and other components to water or an aqueous solvent obtained by mixing water and an organic solvent, or by adding a polythiophene solution or dispersion. It is prepared by separately preparing another coating liquid (for example, a coating liquid for a receptor layer) in advance and then mixing them. When using a commercially available polythiophene solution or dispersion, dilute with water, a water-miscible organic solvent, or an aqueous solvent obtained by mixing water and an organic solvent, or add other components as necessary. Or by mixing with another coating liquid to prepare a coating liquid for forming a layer containing polythiophene.

The coating solution thus prepared is applied or sprayed on the surface of the base sheet or on another layer provided on the base sheet, and then dried and solidified to obtain polythiophene. Can be formed.

When polythiophene is contained in the ink receiving layer, it is usually 1 to 2 times the total solid content of the ink receiving layer.
The polythiophene is mixed at a ratio of 0% by weight, preferably 3 to 10% by weight. If the amount of polythiophene is too small, the antistatic effect will not be sufficiently exhibited. On the other hand, if the amount of polythiophene is too large, coloring becomes strong, and the transparency of the ink receiving layer is impaired. When polythiophene is contained in the primer layer, the polythiophene is usually mixed at a ratio of 5 to 60% by weight, preferably 10 to 30% by weight based on the total solid content of the primer layer.

In order to make the polythiophene contained only in the portion near the surface of the ink receiving layer, the application of the coating liquid for the ink receiving layer is performed in about two to three times. The coating liquid for the ink receiving layer not containing may be applied, and the coating liquid for the ink receiving layer containing polythiophene may be applied only in the last one coating operation.

When the polythiophene is not contained in the ink receiving layer or the primer layer, but is provided with a dedicated antistatic layer containing polythiophene, the polythiophene is added to water or an aqueous solvent obtained by mixing water and an organic solvent. A coating solution is prepared by dissolving or dispersing polythiophene in the coexistence of an anion, and then applying the coating solution on the surface of a base sheet or another layer such as an ink receiving layer by a top coat method or a spray method. After spraying, dry and solidify.

Regardless of whether polythiophene is contained in the ink receiving layer, the primer layer, or the like, or if a dedicated antistatic layer containing polythiophene is provided, the polythiophene-containing layer may be used. The coating amount, the coating amount of the polythiophene itself, and the content ratio of the polythiophene in the coating solution are determined so that the surface electric resistivity of the obtained recording sheet, especially the image receiving surface, is 10 ⁶ to 10 ^12.
It is preferable to adjust so as to be Ω / □ (Ω / square).

[Base Sheet] As the base sheet 2 of the ink jet recording sheet according to the present invention, when the use of the recording sheet is, for example, an OHP sheet or a backlight film, transparency, heat resistance, It is preferably a thermoplastic having dimensional stability and rigidity. Specifically, polyethylene terephthalate resin, polycarbonate resin, acrylic resin, polyvinyl chloride resin, polypropylene resin, polystyrene resin, polyvinyl alcohol resin, polyethylene resin, diacetate resin, triacetate resin, or polyimide resin, etc., the thickness is 5-250 μm, preferably 50-180 μm
For example, a plastic film or a plastic sheet having a length of about m can be exemplified.

When the recording sheet is not required to be transparent, such as specialty paper, glossy paper, label paper, etc., not only the above-mentioned transparent base sheet but also a polystyrene base sheet may be used as the base sheet. Such as synthetic paper, high quality paper, art paper, coated paper, cast coated paper, wallpaper, backing paper, synthetic resin impregnated paper, emulsion resin impregnated paper, synthetic rubber latex impregnated paper, synthetic resin internal paper, paperboard, white plastic White or colored papers, films and sheets such as films and foamed films can be used.

When the adhesion between the base sheet and the ink receiving layer is insufficient, it is preferable to apply a primer treatment or a corona discharge treatment to the surface of the base sheet, or to provide a primer layer.

[Ink Receiving Layer] The ink receiving layer 3 for the ink jet system is formed mainly of a water-soluble resin, an aqueous resin, and a water-soluble resin having wet heat resistance and low-temperature printability.

The water-soluble resin used in the present invention is a resin soluble in water or a mixed solution of water and alcohol.
Various conventionally known water-soluble resins can be used. For example, polyvinyl alcohol, polyvinyl pyrrolidone,
Poly (meth) acrylic acid, cellulosic resin (carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, etc.), polyacrylamide, polyethylene oxide, polyethylene glycol, polyvinyl acetal resin, polyvinyl methyl ether, polyamine, polyethyleneimine, casein,
Examples include water-soluble resins such as gelatin and starch, copolymers thereof, cationically modified products, and anionically modified products. The water-soluble resins may be used alone or as a mixture of two or more.

The aqueous resin is an aqueous emulsion of a hydrophobic resin, for example, an alkyd resin, a polyester resin, a polyvinyl acetate resin, a vinyl chloride-vinyl acetate copolymer resin, NBR.
Resin, SBR resin, polyurethane resin, acrylic resin,
Examples thereof include an aqueous emulsion containing a polyamide resin, a copolymer thereof, or a modified product thereof alone or in combination of two or more.

The modified product of the aqueous resin includes, for example, a hydroxyl group,
It is an aqueous resin having enhanced hydrophilicity by using a monomer or oligomer having a carboxyl group, a sulfone group, a quaternary ammonium group or the like as a copolymerization component or a graft component.

Preferred aqueous resins are water-absorbing polyester resins. The water-absorbing polyester resin has a high adhesiveness to the base sheet, a high film strength, and a high wet strength, so that scars of the print roller marks are less likely to occur on the printing portion during the transportation of the printer.

As the water-soluble resin having wet heat resistance and low-temperature printability, it is soluble in water, alcohol, or a mixed solvent thereof, and has good storage stability in a wide range of environments, for example, temperature range:
Good storage stability at -20 to 50 ° C. and humidity range: 10 to 90% RH is used. In particular, it is preferable that printability and water absorbency hardly decrease even after storage at high temperature and high humidity, and good printability and water absorbency in each environment, especially in a low temperature environment. As the water-soluble resin having wet heat resistance and low-temperature printability, those conventionally used in ink jet recording sheets can be used. For example, polyvinylpyrrolidone, poly (meth) acrylic acid, cellulose-based resins (methylcellulose, hydroxy Water-soluble resins such as propylmethylcellulose and hydroxypropylethylcellulose), polyethylene oxide and polyethylene glycol, copolymers thereof (for example, polyvinylpyrrolidone-vinyl acetate copolymer), cation-modified products and anion-modified products. . These resins may be used alone or in combination of two or more. Among the above resins, polyvinylpyrrolidone and hydroxypropylmethylcellulose are preferable because they are excellent in ink absorbency, printability in a low-temperature and low-humidity environment, and printability after storage in a high-temperature and high-humidity environment.

A preferred combination of a water-soluble resin, an aqueous resin, and a water-soluble resin having wet heat resistance and low-temperature printability includes a combination of polyvinyl alcohol, a water-absorbing polyester, and polyvinyl pyrrolidone.

Normally, each resin has a ratio of [amount of aqueous resin] to [total amount of water-soluble resin and water-soluble resin having wet heat resistance and low-temperature printability] of 7: 3 to 1: 9, and , [Amount of water-soluble resin] to [Amount of water-soluble resin having wet heat resistance and low-temperature printability] are 1: 9 to 9: 1.
Preferably, the former is between 5: 5 and 2: 8 and the latter between 2: 8 and 4: 6. When the mixing ratio of each resin deviates from the above range, ink drying properties, image clarity, printability in high-temperature, high-humidity or low-temperature, low-humidity environments, and printability after storage under high-temperature, high-humidity, etc. The performance may not be balanced.

Particularly when it is desired to prevent blocking,
Organic particles having a primary particle size of 5 to 80 μm and secondary particle sizes of 5 to 20 μm
m to 10 to 10% by weight based on the resin component
It is effective to add at the ratio of If the amount of the organic particles or the inorganic particles is less than the above range, blocking cannot be sufficiently prevented. On the other hand, if the amount is more than the above range, the transparency of the ink receiving layer deteriorates, which is not preferable.

The ink receiving layer may contain an additive, an inorganic compound, or the like for improving the fixing property of the dye. In addition, various surfactants, antioxidants, ultraviolet absorbers, antifoaming agents, various highly hydrophilic modified oils, and the like can be mixed and used as long as the effects of the present invention are not impaired.

To form the ink receiving layer, a coating liquid for an ink receiving layer containing a water-soluble resin, an aqueous resin, and a water-soluble resin having wet heat resistance and low-temperature printability is applied by a conventionally known coating method, for example, Coating and drying on a substrate sheet by any method such as gravure coating, gravure reverse coating, roll coating, wire bar coating, blade coating, knife coating, air knife coating, comma coating, slot die coating, and dip coating.

The thickness of the ink receiving layer is usually 0.1 when dry.
The thickness is 1 to 50 μm, preferably 3 to 30 μm. When the thickness is less than 0.1 μm, the ink absorption amount is often insufficient, whereas when the thickness is more than 50 μm, the manufacturing cost increases, which is not preferable. In order to coat a sufficient amount of the coating liquid, a coating liquid having the same composition may be repeatedly applied a plurality of times.

When polythiophene is added to the ink receiving layer, it is usually 1 to 20 times the total solid content of the ink receiving layer.
Polythiophene is added in a proportion of 3% by weight, preferably 3 to 10% by weight.

[Primer Layer] The primer layer 6 is provided between the base sheet and the ink receiving layer or between the base sheet and the anti-curl layer to improve the adhesion between the ink receiving layer and the anti-curl layer. it can. The primer layer is formed mainly of a binder having good adhesion to both the base sheet and the ink receiving layer, or a binder having good adhesion to both the base sheet and the anti-curl layer. Polythiophene comprising a repeating unit represented by the formula (1) may be added in order to impart antistatic properties to the primer layer.

Examples of the binder for the primer layer include polyester resins, polyurethane resins, polyacrylic resins, polyvinyl formal resins, epoxy resins, polyvinyl butyral resins, polyamide resins, polyether resins, and polystyrene resins. Resin, styrene-acryl copolymer resin and the like can be exemplified. Among them, polyester resins are preferable in terms of adhesion to a substrate, compatibility with polythiophene, and the like, and can be obtained, for example, from Toyobo Co., Ltd. under the trade name of “Vylonal MD1200”.

The primer layer is formed, for example, by adding a binder and, if necessary, polythiophene and other components to a solvent containing water (a mixture of water and a water-miscible organic solvent such as methanol, ethanol, isopropyl alcohol, and normal propyl alcohol). The coating solution is prepared by dissolving or dispersing in a solvent, and applying the solution on a substrate sheet by a known method such as gravure coating, roll coating, wire bar coating and the like, followed by drying.

An optional additive such as a surfactant for improving the wettability of the substrate sheet and an antifoaming agent for suppressing bubbles can be added to the coating liquid for the primer layer. As the surfactant, a phosphate ester-based surfactant can be preferably used. In addition, in order to improve the adhesion of the primer layer and the strength of the coating film, a curing agent such as an epoxy resin, a melamine resin, or an isocyanate compound is added to the coating solution, and after application, the resin of the primer layer is heated or ionized radiation. May be crosslinked.

The thickness of the primer layer is 0.1 to
It is good to be 10 μm, preferably 0.2 to 5 μm.
When the thickness is less than 0.1 μm, the adhesiveness is often insufficient. On the other hand, when the thickness exceeds 10 μm, the recording sheet is undesirably sticky and time-consuming.

When polythiophene is added to the primer layer, it is usually 5 to 6 times the total solid content of the primer layer.
Polythiophene is added at a rate of 0% by weight, preferably 10 to 30% by weight.

[Anti-Curl Layer] An anti-curl layer may be formed on the surface (back side) of the recording sheet opposite to the surface on which the ink receiving layer is formed. The anti-curl layer can be formed using, for example, a water-soluble resin such as that used to form the ink receiving layer, an acrylic resin, a polyester resin, and the like, in particular, an acrylic resin, a modified acrylic resin,
Use of a polyester-based resin is useful because it can impart blocking resistance and slip properties. Polythiophene comprising a repeating unit represented by the formula (1) may be added to the anti-curl layer to impart antistatic properties. The thickness of the curl prevention layer is preferably about 0.1 to 50 μm when dried, and can be formed by the same coating method as that for the above-described ink receiving layer.

[Antistatic Layer] Instead of including polythiophene in the ink-receiving layer or the primer layer, a dedicated antistatic layer containing polythiophene may be provided.
The antistatic layer is formed, for example, on the ink receiving layer or on the anti-curl layer on the back side.

When the antistatic layer containing polythiophene is provided, the coating solution is prepared by dissolving or dispersing polythiophene in water or an aqueous solvent obtained by mixing water and an organic solvent in the presence of a polyanion. Then, it is applied onto the surface of the base sheet or other layers such as the ink receiving layer by a method such as gravure coating, gravure reverse coating, roll coating, or sprayed by a spray method or the like, and then dried and solidified. Let it. In this case, the coating amount of the polythiophene is preferably adjusted so that the surface electrical resistivity of the recording sheet becomes 10 ⁶ to 10 ¹² Ω / □. The thickness of the antistatic layer is usually about 0.001 to 0.1 μm when dried.

In the present invention, as long as the effects of the present invention are not impaired, conventionally known cations, anions and amphoteric ions other than polythiophene comprising a repeating unit represented by the formula (1) Either a system-based or a non-ionic system antistatic agent may be used in combination. Examples of antistatic agents that can be used in combination include, for example, quaternary ammonium salts, cationic antistatic agents such as polyamine derivatives, anionic antistatic agents such as alkyl phosphates, and nonionic antistatic agents such as fatty acid esters. Can be exemplified.

[0062]

EXAMPLES Hereinafter, the recording sheet according to the present invention will be described in more detail through examples.

Example 1 A base film having a thickness of 10
A 0 μm PET (polyethylene terephthalate) film (T-60, manufactured by Toray Co., Ltd.) was prepared, and a coating solution for primer layer having the following composition having a coating amount of 0.
Coating and drying were performed at 5 g / m ² to form a primer layer containing polythiophene. Further, a coating liquid 1 for an ink receiving layer having the following composition was formed on the primer layer.
Was applied and dried so that the coating amount at the time of drying was 8.0 g / m ² to form an ink receiving layer, thereby obtaining a recording sheet.

<Coating liquid 1 for primer layer> Polyester resin (MD1930, manufactured by Toyobo): 70 parts by weight as a solid content Polythiophene (1% aqueous solution of Baytron P, manufactured by Bayer AG): 30 parts by weight as a solid content Water / Isopropanol (1/1): proper amount <Coating liquid 1 for ink receiving layer>-Polyester resin (Vylonal MD1200, manufactured by Toyobo): 28 parts by weight as a solid content-Polyvinyl alcohol (PVA 217, manufactured by Kuraray): as a solid content 35 parts by weight ・ Polyvinylpyrrolidone (PVP K-90, BASF
: 35 parts by weight as solids ・ Silica (Sylysia 470, manufactured by Fuji Silysia): 2 parts by weight as solids ・ Water / isopropanol (2/1): appropriate amount

Example 2 A base film having a thickness of 10
A 0 μm PET (polyethylene terephthalate) film (T-60, manufactured by Toray Co., Ltd.) was prepared, and a primer layer coating liquid 2 having the following composition was dried on the image receiving surface side at a coating amount of 0.
The primer layer was formed by coating and drying at 5 g / m ² . Further, on the primer layer, an ink receiving layer coating liquid 2 having the following composition was dried at a coating amount of 8.0 g / d.
and coating and drying so that m ² to form an ink receiving layer containing polythiophene, to obtain a recording sheet.

<Coating liquid 2 for primer layer>-Polyester resin (Byron 200, manufactured by Toyobo): 10% by weight as solid content-Methyl ethyl ketone / toluene (1/1): balance <Coating liquid 2 for ink receiving layer> -Polyester resin (Vylonal MD1200, manufactured by Toyobo): 20 parts by weight as solids-Polyvinyl alcohol (PVA 217, manufactured by Kuraray): 24 parts by weight as solids-Polyvinylpyrrolidone (PVP K-90, BASF)
): 24 parts by weight as a solid content ・ Silica (Sylysia 470, manufactured by Fuji Silysia): 2 parts by weight as a solid content ・ Polythiophene (1% aqueous solution of Baytron P, manufactured by Bayer AG): 30 parts by weight as a solid content (2/1): appropriate amount

Example 3 A base film having a thickness of 10
A 0 μm PET (polyethylene terephthalate) film (T-60, manufactured by Toray Co., Ltd.) was prepared, and the primer layer coating liquid 2 used in Example 2 was dried on the image receiving surface side at a coating amount of 0.5 g / d The primer layer was formed by coating and drying so as to obtain m ² . On the primer layer, the coating amount of the ink receiving layer coating liquid 1 used in Example 1 when dried was 8.0.
g / m ² and dried to form an ink receiving layer. Further, an antistatic layer coating liquid 1 having the following composition was applied and dried on the ink receiving layer to form an antistatic layer containing polythiophene, thereby obtaining a recording sheet. Since the antistatic layer was very thin and the amount of coating could not be controlled, the coating was performed so that the surface electrical resistivity was within an appropriate range.

<Coating liquid 1 for antistatic layer> Polythiophene (1% aqueous solution of Baytron P, manufactured by Bayer AG): proper amount Water / isopropanol (1/2): proper amount

[Comparative Examples 1-3] In place of the polythiophene used in Examples 1-3, quaternary ammonium salts (TB-
34, manufactured by Matsumoto Yushi Co., Ltd.), and the recording sheets of Comparative Examples 1 to 3 were obtained in the same manner as in the examples.

[Evaluation Test] (1) Evaluation of Image Quality Using the recording sheets obtained in each of Examples and Comparative Examples,
Under each environment of 23 ° C. and 50% RH and 10 ° C. and 10% RH, an image was output using an inkjet printer (BJC-400J, manufactured by Canon), and the image quality was visually observed. The evaluation criteria are as follows. The evaluation results are shown in Table 1.

<Evaluation Criteria for Image Quality> A: Uniform image without bleeding.

Δ: The image was slightly blurred and uneven.

×: Bleeding and unevenness were severe.

(2) Surface Electric Resistivity A voltage of 100 V was applied to the surface of each recording sheet under each of the above-mentioned environments, and the surface electric resistivity 10 seconds after the start of application was measured using a surface resistance measuring instrument (Hiesta). , Manufactured by Mitsubishi Yuka). The results are shown in Table 1.

[0075]

[Table 1]

[0076]

As described above, in the recording sheet of the present invention, polythiophene comprising a repeating unit represented by the formula (1) is used as an antistatic agent.
This polythiophene always exhibits excellent antistatic properties even when the environmental humidity changes. Also, this polythiophene
It hardly causes stickiness, bleed-out, or contamination of the receptor layer, so that the printability and storability of the recording sheet are not impaired. Further, since the polythiophene has high transparency, the transparency of the recording sheet is not impaired. Therefore, the recording sheet of the present invention has excellent antistatic properties as well as printability, transparency and storage properties.

The above-mentioned polythiophene is positively charged and dissolved or dispersed in water or a mixed solvent of water and a water-miscible organic solvent in the presence of a polyanion. Therefore, by preparing a coating solution such as an antistatic layer coating solution or a receiving layer coating solution containing the polythiophene and applying the coating solution onto the base sheet of the recording sheet, the polythiophene-containing layer can be easily formed. Can be formed.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a cross section of an example of a recording sheet of the present invention.

FIG. 2 is a diagram schematically showing a cross section of another example of the recording sheet of the present invention.

FIG. 3 is a diagram schematically showing a cross section of still another example of the recording sheet of the present invention.

[Explanation of symbols]

 Reference Signs List 2 base sheet 3 ink receiving layer 3a lower part of ink receiving layer 3b part near surface of ink receiving layer 4 curl / antistatic layer 5 antistatic layer 6 primer layer

Claims (9)

[Claims] 1. An antistatic agent represented by the following formula (1): [In the formula (1), R ¹ and R ² each independently represent hydrogen or an alkyl group having 1 to 4 carbon atoms, or have 1 to 4 carbon atoms which may be substituted together. Form an alkylene group. A recording sheet for recording characters, images and / or other visually recognizable information, comprising a layer containing a polythiophene comprising a repeating unit represented by the following formula: 2. An ink jet recording sheet comprising at least a base sheet and an ink receiving layer mainly composed of a water-soluble resin and / or a water-based resin provided on the base sheet, wherein 2. The recording sheet according to claim 1, wherein at least one of the layer and the other layer contains polythiophene composed of the repeating unit represented by the formula (1). 3. 3. The recording sheet according to claim 2, wherein polythiophene comprising a repeating unit represented by the formula (1) is contained in the ink receiving layer. 4. In a portion near the surface of the ink receiving layer,
4. A polythiophene comprising a repeating unit represented by the formula (1) is contained.
Recording sheet according to 1. 5. The method according to claim 1, wherein the formula (1) is provided on the ink receiving layer.
Characterized in that an antistatic layer containing a polythiophene comprising a repeating unit represented by is provided,
The recording sheet according to claim 2. 6. A primer layer containing a polythiophene comprising a repeating unit represented by the formula (1) is provided between the base sheet and the ink receiving layer. Recording sheet according to 1. 7. The recording sheet according to claim 6, wherein the primer layer contains a polyester resin as a binder. 8. The ink receiving layer is provided on one side of the base sheet, and the formula (1) is provided on the other side.
Characterized in that an antistatic layer containing a polythiophene comprising a repeating unit represented by is provided,
The recording sheet according to claim 2. 9. In producing a recording sheet for recording characters, images and / or other visually recognizable information, the following formula (1) is used as an antistatic agent: [In the formula (1), R ¹ and R ² each independently represent hydrogen or an alkyl group having 1 to 4 carbon atoms, or have 1 to 4 carbon atoms which may be substituted together. Form an alkylene group. A coating solution obtained by dissolving or dispersing a polythiophene comprising a repeating unit represented by the formula (1) directly or via another layer on a base sheet, and drying to form a layer having antistatic properties. A method for producing a recording sheet.