JPH1178223A - Printing sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the elution of soluble components of printing layers into a printing H-soln. and to obtain a good printing image in a printing sheet performing printing by oleophilic ink and printing by aq. ink to mutually bond the printing layers under pressure. SOLUTION: In a printing sheet wherein first data is printed on the printing layer formed on at least one surface of a base material by oleophilic ink and second data is printed on the same printing layer by aq. ink, a pressure-sensitive adhesive, a water-soluble polymer with pH of 7 or more and a cationic crosslinking agent are added to the printing layer formed on the surface of the base material. The pressure-sensitive adhesive is at least one of a natural rubber adhesive and polyacrylic ester adhesive and the cationic crosslinking agent is a cationic substance having an epoxy group, a methylol group, an isocyanate group or an amino group. By this constitution, intermolecular crosslinking is performed and a cation group can be introduced into the water- soluble polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to, for example, a method in which general information such as a table or a pattern is printed on a print layer on the surface with lipophilic ink, and then variable information is printed with a water-based ink at a predetermined location by an ink jet printer. The present invention relates to a printing sheet of a type in which a printed print layer is releasably adhered by being folded and folded.

[0002]

2. Description of the Related Art In recent years, there has been a remarkable development of an ink jet system for printing and printing on a sheet using water-based ink. For example, a computer terminal processing system for printing and printing personal information (variable information) on a postcard and mailing the postcard to an individual. As an apparatus, an ink jet printer capable of high-speed printing at a printing speed of 300 m / min is used. In such a system, when all information (general information and personal information) is printed on a sheet by an ink jet printer, or on a sheet on which general information is printed in advance by various printing machines such as a continuous offset printing machine,
There are two cases in which only the personal information is printed later by an inkjet printer. Also, as postcard paper,
Compression postcards that have been folded so that personal information can be concealed and releasably adhered have been used.

In general, there are many ink-jet sheets in which a porous layer is formed by coating a pigment such as silica on the paper surface, or in which a resin that absorbs an aqueous ink by dissolution or swelling is coated. Also, in order to prevent bleeding of the ink due to water wetting,
It contains a water-soluble cationic dye fixing agent, a relatively low-molecular-weight water-soluble cationic resin having a primary to tertiary amino group or a quaternary ammonium group, and the like. The same applies to a newly developed pressure-bonded postcard for ink jet which has been recently developed (for example, Japanese Patent Application Laid-Open No. 9-39378).
JP-A-9-11669, JP-A-9-119094
issue). By the way, the dye fixing agent or the cationic resin can convert the anionic dye contained in the aqueous ink into water-insoluble, but the other parts are water-soluble and easily elute. When offset printing is performed on such an ink jet sheet, the components are easily eluted into the printing H liquid, causing troubles such as contamination of the water roller. did.

[0004]

That is, when printing personal information with an ink jet printer after offset printing, if a normal offset printing sheet is used, the ink jet suitability is poor. It had characteristics unsuitable for printing. Therefore, it is suitable for multicolor offset printing using a lipophilic ink, particularly a UV curable ink and an H liquid for printing, and has no problem in ink fixing property, water resistance and color development even when printed by an inkjet method. Printing sheets for postcards have been strongly desired. However, such a printing sheet does not exist at present, and at present, there is little study or research. Therefore, the present invention has been made in view of the above circumstances, and it is possible to provide a printing sheet suitable for pressure-bonded postcard paper and the like, which can achieve both offset printing with lipophilic ink and ink-jet printing with water-based ink. The purpose is.

[0005]

According to the printing sheet of the present invention, the first information is printed with a lipophilic ink on a printing layer formed on at least one surface of the base material, and the printing information is printed on the printing layer. In a printing sheet on which the second information is printed with an aqueous ink, the print printing layer may include a pressure-sensitive adhesive,
It is characterized by containing a water-soluble polymer having a pH of 7 or more and a cationic crosslinking agent.

According to experiments by the present inventors, a cationic dye fixing agent or a low molecular weight compound (for example, having a molecular weight of 1000
Even if a cationic resin having a primary to tertiary amino group or a quaternary ammonium group described below is included, the resin is easily soluble in the printing liquid H because the resin is originally water-soluble. It turned out to be. The resin eluted in this way
The solution accumulates around the supply port of the printing H liquid via the drum of the offset printing machine in reverse, and the surface viscosity of the water roller increases, which causes a problem that the cleaning must be frequently performed during printing. When these cationic fixing agents are excluded, although printing troubles are solved, deterioration of water resistance is promoted on the contrary, and the problem that the printed surface cannot be read when the printed surface is wet with rainwater or the like occurs. . To solve this problem, the print print layer contains an alkaline water-soluble polymer having a pH of 7 or more and a cationic crosslinking agent,
An attempt was made to crosslink the water-soluble polymer intermolecularly and to introduce a primary to tertiary amino group or a quaternary ammonium group into the main chain or side chain of the water-soluble polymer. The result is very good, the elution of the cationic water-soluble component from the treated surface of the substrate to the printing H liquid is greatly improved, and the fixability of the aqueous ink of the ink jet printer is inferior to ordinary ink jet paper. It was confirmed that it could be improved to an unacceptable level.

The reason is considered as follows. That is, even if the printing liquid H adheres to the portion where the lipophilic ink has not been transferred during offset printing, the water-soluble polymer is intermolecularly crosslinked, and the cationic group is also bonded to the main chain or side chain of the polymer. Therefore, the water resistance is improved, and the migration of the cationic group does not occur. On the other hand, the anionic dye of the aqueous ink used in the ink jet method is surely fixed by the positive polarity of the primary to tertiary amino groups and quaternary ammonium groups. As a result, the printability of the lipophilic ink is improved, and the fixability of the subsequent aqueous ink is maintained.

The present invention is suitable for a printing sheet in which an aqueous ink is printed by an ink-jet method after printing with an lipophilic ink, and the print-printed layers are pressure-bonded to each other. It can also be used for applications such as printing with a lipophilic ink or writing with a lipophilic ink using a writing implement or the like using an aqueous ink, followed by pressure bonding. In particular, after printing general information in advance with lipophilic ink, personal information is extracted by a computer and printed by an ink jet printer, and thereafter, the printed information layers are pressed together to conceal the personal information and sent to each individual. Ideal for such applications. Examples of such applications include the use of envelopes and postcards in banks and government offices that periodically send variable information to individuals, and the field of direct mail, and the range of use is extremely wide.

Next, the materials constituting the printing sheet of the present invention will be described. <Pressure-Sensitive Adhesive> The pressure-sensitive adhesive is included in order to impart a property that the printing sheet is temporarily adhered by pressure and can be easily peeled off by an artificial operation. Examples of conventional pressure-sensitive adhesives that are bonded by applying pressure include, for example, vinyl chloride resin, vinylidene chloride resin, natural rubber, polyacrylate, synthetic rubber resin, and the like.
It is also possible to select and use these arbitrarily. However, since the adhesiveness is sufficient and the adhesive peels off smoothly at the interface between the adhesives, among the pressure-sensitive adhesives, in particular, natural rubber adhesives and polyacrylate adhesives are particularly preferred. Those containing at least one of them as a main component are preferred. More preferred natural rubbers include raw natural rubber latex, vulcanized natural rubber latex, and natural rubber latex obtained by graft copolymerization of methyl methacrylate (MMA).

The proportion of the pressure-sensitive adhesive contained in the print layer is preferably in the range of 10% by weight to 75% by weight. If the amount is less than 10% by weight, a sufficient adhesive force cannot be obtained when pressurized, and if it exceeds 75% by weight, the adhesive force is too strong to be able to be peeled off smoothly or the absorbability of the water-based ink is extremely poor. Or become.

<Water-Soluble Polymer> The water-soluble polymer of the present invention is a material having reactivity with an epoxy group, a methylol group, an isocyanate group, an amino group, etc., and is easily prepared with an H liquid for printing after cross-linking between molecules. It is a polymer with a molecular weight that is difficult to elute. . Examples of the water-soluble polymer include water-soluble cellulose derivatives such as carboxymethyl cellulose (CMC), casein, dextrin, starch, modified starch, polyvinyl alcohol (PVA), modified polyvinyl alcohol, polyethylene oxide, polyvinyl pyrrolidone (PVP), Water-soluble polyamines, polyacrylic acids, polyacrylamides, water-soluble acrylic resins, water-soluble polyester resins, polyamide resins, cation-modified modified products of these resins, and cationic cross-linking agents can be exemplified.

<Cationic Crosslinking Agent> The cationic crosslinking agent of the present invention crosslinks the above-mentioned water-soluble polymer intermolecularly, and simultaneously introduces a tertiary amino group or a quaternary ammonium group into the molecule. Such a material is, for example, a resin having a plurality of functional groups such as an epoxy group, an isocyanate group, a methylol group, and an amino group and having a cationic property. Preferred examples of the cationic crosslinking agent include polyamide-polyamine-epichlorohydrin resin and polyamide obtained by reacting an epichlorohydrin with a basic low-molecular-weight polyamide derived from an aliphatic dicarboxylic acid (eg, adipic acid) and a polyalkylene-polyamine. Examples thereof include partially methylolated polyurea and quaternized methylolmelamine.

According to experiments conducted by the present inventors, it was found that, among the above cationic cross-linking agents, a polyamide-epichlorohydrin resin and a carboxyl-modified PVA among water-soluble polymers whose pH was previously adjusted to 8 or more were used. It was confirmed that good results were obtained. The ratio of the water-soluble polymer and the cationic crosslinking agent contained in the print layer is preferably in the range of 1 to 200% by weight based on the water-soluble polymer.
When the proportion of the cationic crosslinking agent is less than 1% by weight,
The ink absorbency is poor, and the water resistance of the image becomes insufficient.
If it is added in excess of 0% by weight, the water-soluble ink will have poor absorbency. In the case of an epoxy-based cationic cross-linking agent such as polyamide-epichlorohydrin resin, it is very important to control the pH of the water-soluble polymer, and at least pH 7 or more (that is, alkaline), and more preferably pH 9 or more, Results were obtained.

<Other components> In the present invention,
In the print layer, in addition to the above-described pressure-sensitive adhesive, a water-soluble polymer and a cationic crosslinking agent, fine-grained filler, synthetic rubber,
A thermoplastic resin or the like can be contained. Here, the finely divided fillers can be classified into inorganic fillers and organic fillers. As the inorganic filler, calcium carbonate,
Clay, kaolin clay, talc, calcium sulfate, barium sulfate, silica, zinc oxide, titanium oxide, zinc sulfide, zinc carbonate, aluminum hydroxide, alumina, aluminum silicate, calcium silicate, diatomaceous earth, magnesium silicate, hydrated Examples include aluminum oxide, mica, and glass powder. Among these inorganic fillers, when considering the absorbability of the aqueous ink, the blocking resistance, and the acceptability of the lipophilic ink, silica, calcium carbonate, talc, kaolin clay, aluminum hydroxide alone or in combination of two or more It is desirable to use it.

Examples of the organic filler include cellulose powder, sweet potato starch, potato starch, wheat starch, corn starch, rice starch, tapioca starch, styrene beads, methyl methacrylate beads and the like. Since these organic fillers have a large average particle size of 5 to 30 μm, they can improve blocking resistance and impart slipperiness of the printing sheet. Therefore, these organic fillers are preferably added in powder form. As synthetic rubber, SBR, NB
Butadiene rubber such as R and MBR, neoprene rubber and the like can be mentioned. Examples of the thermoplastic resin include polyvinyl acetate, polyacrylic acid, and polyacrylate.

These fine-grained fillers, synthetic rubbers and thermoplastic resins are used for improving the inking property and absorptivity and blocking resistance of lipophilic inks and water-based inks, preventing the fillers from falling off, adjusting the viscosity of paints and wetting. Can be appropriately added for the purpose of improving the properties. In the paint, if necessary, additives such as a dispersant, an antifoaming agent, a surfactant, an antioxidant, an ultraviolet absorber, a fungicide, a deodorant, and a fluorescent whitening agent can be added. .

In order to form a print layer on a substrate, the above-mentioned material is dispersed or dissolved in water to form a coating material. For example, a size press device or a gate roll device provided during a paper-making process of a substrate such as paper. Alternatively, apply with a spray device,
After coating with a usual coating means such as a roll coater, a bar coater, a blade coater, an air knife coater, a rod blade coater or a gravure roll coater, it is dried.

The type of substrate used in the present invention is not particularly limited to paper, and either a transparent substrate or an opaque substrate can be used. When transparency is required for an image printed by using, for example, a transparent plastic film is suitable. Examples of the transparent substrate include, for example, polyester resin, diacetate resin, triacetate resin, acrylic resin, polycarbonate resin, polyvinyl chloride resin, polyimide resin, cellophane, celluloid and other films. No. Preferred examples of the opaque substrate include, for example, ordinary paper, cloth, synthetic paper, and the like, and those obtained by subjecting the above transparent substrate to opacity treatment by a known means such as filling with a white pigment or fine foaming. Is mentioned. In the case of wood pulp paper such as paper, coated paper or cast paper provided with a coating layer in advance can also be used. Further, a laminated paper or the like obtained by bonding these resin films to the surface of paper or processing with a molten resin can also be used. In addition, the sheet obtained by applying the above-described print print layer to the base material can be used as it is as a printing sheet, but the surface may be smoothed with a super calender or the like.

[0019]

Next, the present invention will be described in more detail with reference to the following embodiments. However, the printing sheet of the present invention is not limited to these embodiments. (Example 1) Foam paper 81.4 g / m ² as base material
(KPF-N manufactured by Kishu Paper) was used. On this substrate,
A paint having the following composition was applied at a coating amount (solid content) of 6 g / m.
² , and then dried by blowing hot air of 105 ° C. for 2 minutes to produce a printing sheet. "Paint"-100 parts by weight of MMA-grafted natural rubber adhesive-65 parts by weight of silica (Mizukasil P-78A manufactured by Mizusawa Chemical Co., Ltd.)-40 parts by weight of constarch (manufactured by Nippon Shokuhin Kako Co., Ltd.)-Carboxyl-modified PVA (Nippon Synthetic Chemical Company) 12 parts by weight of Gosenal T-350 manufactured by Toho Kagaku Co., Ltd.
-71) 130 parts by weight (pH 9)

Example 2 A printing sheet was prepared in the same manner as in Example 1 except that a paint having the following composition was used. "Paint"-100 parts by weight of cold seal adhesive for secret letter (manufactured by Sanyo Chemical Industries)-36 parts by weight of silica (Mizukasil P-78A manufactured by Mizusawa Chemical Co., Ltd.)-22 parts by weight of constarch (manufactured by Nippon Shokuhin Kako) 7 parts by weight of carboxyl-modified PVA (Gosenal T-350 manufactured by Nippon Gohsei) ・ Cation-modified epoxy-based crosslinker (FL manufactured by Toho Chemical Co., Ltd.)
-71) 100 parts by weight (pH 8)

Example 3 A printing sheet was prepared in the same manner as in Example 1 except that a paint having the following composition was used. "Paint"-100 parts by weight of MMA-grafted natural rubber adhesive-65 parts by weight of silica (Mizukasil P-78A manufactured by Mizusawa Chemical Co., Ltd.)-40 parts by weight of constarch (manufactured by Nippon Shokuhin Kako Co., Ltd.)-Polyvinylpyrrolidone (manufactured by BASF) 12 Parts by weight-220 parts by weight of polyamide epichlorohydrin resin (wet master GT-360 manufactured by Toho Chemical Co., Ltd.) (pH
7)

(Comparative Example 1) Foam paper 8 as a base material
1.4 g / m ² (KPF-N manufactured by Kishu Paper) was used. A coating material having the following composition was applied to this base material so that the coating amount (solid content) was 6 g / m ^2, and thereafter, 10 g
Hot air of 5 ° C. was applied for 2 minutes to dry. "Paint"-100 parts by weight of MMA-grafted natural rubber adhesive-75 parts by weight of silica (Mizukasil P-78A manufactured by Mizusawa Chemical Co., Ltd.)-50 parts by weight of constarch (manufactured by Nippon Shokuhin Kako Co., Ltd.)-SBR (Nipol LX416 manufactured by Zeon Corporation) ) 15 parts by weight Furthermore, a specially modified polyamine (Polyfix 60 manufactured by Showa Kogaku KK) was used as a cationic resin on the coating layer.
The 10% aqueous solution of 1) was applied so as to have a wet weight of 10 g / m ² , and then heated with 105 ° C. hot air for 1 minute to dry, thereby producing a printing sheet.

(Comparative Example 2) The same as Comparative Example 1 except that the paint of Comparative Example 1 was used and that the cationic resin was a 10% aqueous solution of a polyamine resin (PNF-70, manufactured by Nikka Chemical Co., Ltd.). To prepare a printing sheet.

(Comparative Example 3) A printing sheet was prepared in the same manner as in Comparative Example 1 except that the paint of Comparative Example 1 was used and a 10% aqueous solution of a cationic resin (HP-20K manufactured by Senka) was used. Produced.

Next, with respect to the samples prepared in the above Examples and Comparative Examples, water resistance to the H solution for printing, ink absorption, ink spreading, water transfer resistance, image transfer to the opposing surface, blocking resistance and An evaluation test of the adhesive strength was performed. The test method is as follows, and the results are shown in Table 1. (Recording characteristics of inkjet ink) Inkjet printer MachJet MJ- manufactured by Seiko Epson Corporation
Images were printed using 1050V2, and the above characteristics were examined.

Water resistance to printing liquid H At room temperature, 50 cc of pure water is placed in a beaker, and a sample (2.5 cm × 2.5 cm) is immersed in the water for 1 minute. After removing the sample, a few drops of 0.1% toluidine blue indicator were added into the water of the beaker,
Titration was performed using a 400 polyvinyl potassium sulfate solution (PVSK), and the amount of PVSK when the color of the indicator changed from blue to bright reddish purple was measured. The contents of the evaluation are shown below. ◎ PVSK amount less than 0.5 ml: good water resistance △ PVSK amount 0.5 ml or more and less than 0.1 ml: slightly poor in water resistance × PVSK amount less than 1.0 ml: poor water resistance

Ink Absorbability Five minutes after printing, a filter paper was pressed against the print surface, and whether or not the aqueous ink had migrated to the filter paper was visually observed. The contents of the evaluation are shown below. ：: no migration to the filter paper side, good ink absorbency ×: migration to the filter paper side, poor ink absorption

Spreading of Ink The printed characters were visually observed to determine whether the characters could be clearly confirmed without bleeding. The contents of the evaluation are shown below. ：: The printed characters are clearly confirmed. X: The bleeding is large and the characters are not clear.

Water transfer resistance After the filter paper is soaked in water, excess water on the surface is removed, and the filter paper is bonded to the printing surface. A pressure of 100 kg / cm ² is applied for 2 seconds to determine whether or not the ink has transferred to the filter paper. Was visually observed. The contents of the evaluation are shown below. ◎: No transfer to the filter paper side at all, extremely good water transfer resistance of the ink. ○: Slight transfer to the filter paper side, but practically no problem and good water transfer resistance of the ink. ×: Transfer to the filter paper side. There is migration, poor water transfer resistance of ink

Transfer of Image to Opposite Surface The sample printed by the above inkjet printer was
Postal mailer "Partner" (Nippon Rika Paper)
Was set to 100 μm, and the obtained printing sheet was Z-folded, passed through a width of 100 mm, and adhered under pressure. After leaving for 1 hour after pressure bonding, transfer of the image to the opposing surface when peeled was observed. The contents of the evaluation are shown below. ：: There is no transfer of the image to the opposing surface ○: There is a slight transfer of the image to the opposing surface, but there is no practical problem at all △: There is a little transfer of the image to the opposing surface ×: The opposing surface There is an image transfer to

Blocking Resistance The printing layers were superimposed, applied with a pressure of 500 g / cm ² , and allowed to stand at 50 ° C. for 24 hours. Then, it was peeled off and the state of the surface was visually observed. The contents of the evaluation are shown below. ○: Light peeling resistance, no surface pain, no blocking problem ×: Pulp fiber fluff on the surface, blocking problem

Adhesive force The printed print layers of the samples were adhered under pressure under the same conditions as in the above test method, left for 1 hour, and then subjected to a Tensilon tensile tester (Tensilon RTM-10 manufactured by Orientec Co., Ltd.).
Using 0), T-peeling was performed on the surfaces where the print print layers were pressure-adhered to each other at a pulling speed of 300 mm / min, and the adhesive strength was measured.

From these test results, the practicality of the printing sheet was comprehensively determined. The evaluation is as follows. ◎: Excellent in practical use ○: Available in practical use ×: There is a practical problem

As is clear from the results shown in Table 1, in Examples 1 to 3 in which the print print layer contains a water-soluble polymer and a cationic cross-linking agent together with the pressure-sensitive adhesive, printing was performed with a lipophilic ink, and It satisfies all functions as a printing sheet for printing by the ink jet method.

Further, in Examples 1 and 3, the carboxyl-modified PVA or PVP was included as a natural rubber-based adhesive, a cationic cross-linking agent and a water-soluble polymer, so that water resistance and water resistance to the H solution for printing were used. Transferability is a very favorable result. On the other hand, Comparative Examples 1 to
No. 3 used a printing resin because a cationic resin or a cationic dye fixing agent was used instead of a cationic crosslinking agent in the printing layer.
It was confirmed that water resistance to the liquid was inferior, and troubles with lipophilic ink were likely to occur. In the examples and comparative examples, the water-based ink absorbency, spread,
Adhesive strength, image transfer to opposing surface, blocking resistance, etc.
The state printed by the inkjet method was all good.

[0036]

[Table 1]

The present invention is not limited to a printing sheet for ink jet printing, but can be applied as a printing sheet for various printing apparatuses such as a laser printer. Further, the sheet is not limited to the one for printing, and may be a sheet for handwriting. For example, the present invention can be applied to a crimped postcard that is written by hand and then folded in two, and the folded surfaces are bonded and mailed. In this case, a heat-sensitive adhesive may be contained together with the pressure-sensitive adhesive, and the heat-sensitive adhesive may be bonded using an iron or the like. Such a crimped postcard is very convenient because the postcard can be used like a sealed letter. further,
The object to be bonded is not limited to a sheet-like object, and may be, for example, a rigid body such as a wall or a desk.

[0038]

As described above, according to the printing sheet of the present invention, the printing print layer contains a pressure-sensitive adhesive, a water-soluble polymer having a pH of 7 or more, and a cationic cross-linking agent. Even when printing with the ink and printing with the aqueous ink are performed, the soluble component of the print print layer is not eluted, and an effect is obtained in which a good print print image can be obtained.

Claims (5)

[Claims] 1. Printing wherein first information is printed with a lipophilic ink on a print print layer formed on at least one surface of a base material, and second information is printed with a water-based ink on the print print layer. A printing sheet, wherein the printing print layer contains a pressure-sensitive adhesive, a water-soluble polymer having a pH of 7 or more, and a cationic crosslinking agent. 2. The printing print layer is brought into contact with each other by folding the printing sheet, and is peelable at the contact surface by containing the pressure-sensitive adhesive in the contact surface of these printing sheets. The printing sheet according to claim 1, wherein the printing sheet is adhered to the printing sheet. 3. The adhesive according to claim 1, wherein the pressure-sensitive adhesive is an adhesive composed of at least one of a natural rubber adhesive and a polyacrylate adhesive. Printing sheet. 4. The printing sheet according to claim 1, wherein the cationic crosslinking agent is a cationic substance having an epoxy group, a methylol group, an isocyanate group or an amino group. 5. The printing sheet according to claim 1, wherein the water-soluble polymer is a water-soluble polymer having a carboxyl group, a hydroxyl group, or an amino group.