JP2004122779A - Pressure bonding paper for inkjet and producing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure bonding paper for inkjet using a paint with high fluidity which makes pressure bonding paper for inkjet in a single coating layer and with excellent water and weather resistance when printed on a confidential face by an inkjet printer, and the printing on the confidential face does not transfer to an opposed face when an stripping occurs after pressure bonding is done on the confidential face. <P>SOLUTION: The pressure bonding paper is made folded and bonded so that each confidential face of the paper having a confidential face can be bonded removably through an adhesive composition coated on the confidential faces. A cold sealant, polydimethylamine epichlorohydrin and/or modified dimethylamine epichlorohydrin condensate are contained in the adhesive composition. More than 5 parts weight polydimethylamine epichlorohydrin and/or modified dimethylamine epichlorohydrin condensate are(is) blended with the 100 parts weight cold sealant. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention provides an ink-jet pressure-sensitive paper used for a pressure-bonded postcard and the like, in which the confidential surfaces that have been pressed can be peeled off when necessary, and the personal information printed on the confidential surface can be confirmed using an ink-jet printer by peeling. It relates to a manufacturing method.

In recent years, with the amendment of the postal law, postcards have been developed that have lower postage rates than sealed letters and have confidentiality that enables confidentiality of communication as well as sealed letters. Above all, after printing various information on a layer of a pressure-sensitive adhesive having releasability coated on the confidential surface of the paper, the paper is folded in two or three, and a high pressure of 50 to 100 kg / cm ² is applied. By pressing the confidential surfaces together via the pressure-sensitive adhesive, the so-called "crimping postcard", which constitutes the form of a postcard, is rapidly progressing as a switch from a sealed letter in the industry where a large amount of notification documents need to be sent. In.

よ り Conventionally, a laser beam method has been used as a method for printing various types of information on pressure-bonded postcards. However, in the laser beam method, it is necessary to heat the compression postcard for fixing the toner, and there is a problem that the heating causes an unpleasant odor and the aging of the pressure-sensitive adhesive proceeds. In addition, despite the fact that most printers employing the laser beam method are of the continuous type, after printing the base paper of the pressure-bonded postcard, it is not a roll-up type but a folding type. Is developed and fed, and printing is performed. When a large load is applied to the contact portion of the bonding surface in this step, there is a problem that blocking easily occurs.

Therefore, recently, a high-speed inkjet method using a water-soluble ink (sometimes referred to as “water-based ink”) has attracted attention as a printing method replacing the laser beam method. The high-speed ink jet system is a system in which printing is directly performed on a web by a continuous nozzle continuous ink jet system in the same manner as printing, and the ink portion is locally heated and dried by a high frequency drying device. According to such a high-speed ink jet system, a large amount of information processing can be performed by low-speed printing at a high running speed of up to 300 m / min. A water-soluble ink used in a high-speed ink jet system, for example, a water-soluble ink such as Cytex # 1007, has a high dielectric constant and has a high dielectric constant against heat generation because the dye is 5 to 6% by weight and most of the other is water. It has the property of being efficient.

On the other hand, in addition to the functions naturally required for press-bonded paper, ink-jet press-bonded paper has the same printing quality, water resistance and weather resistance of ink, Dryness, ink strike-through prevention performance, and the like are required. Among these qualities, a higher degree of water resistance of the ink is required from the viewpoint of preventing accidents due to rain or the like during mailing of the postcard.

水性 The water resistance in this case is the water resistance of a water-soluble ink using a direct dye or an acid dye as a coloring agent. In this type of water-soluble ink, the dye is made water-soluble by a salt of a sulfone group and / or a carboxyl group in the dye molecule, and a portion giving water solubility has a strong negative charge. Here, the main one of the conventional water-resistant technologies of the water-soluble ink is that the dye molecules are trapped electrically by interposing a cationic polymer in the ink-receiving layer, and the water-soluble ink is brought into close proximity with the evaporation of water. The dye molecules are fixed to the ink receiving layer by applying Van der Waals force between the two. As the polymer interposed in the ink receiving layer, specifically, for example, quaternized polyvinylpyridine, polyethyleneimine, quaternized polyethyleneimine, polyallylsulfone, dicyandiamide condensate, polyethylenepolyamine-based polymer, polyallylamine, polydiallylamine, etc. Many cationic polymer applications have been introduced.

In Japanese Patent Application Nos. Hei 7-315632 and Hei 8-51487, a modified polyethylene imine is used as a main component of a waterproofing agent for ink-jet pressure-sensitive adhesive paper, the pH of the paint is kept high, and the limit amount is kept in a negative ion state. A method using the following polycation or inorganic salt in combination is proposed.

However, the waterproofing agent commonly used in these patents, that is, the modified polyethyleneimine has a defect that it has poor weather resistance and yellows with time. Therefore, an object of the present invention is to develop a pressure-sensitive adhesive paper for ink jet which has high water resistance and good weather resistance by treating a substrate with a one-component paint having high fluidity and stability without using modified polyethyleneimine.

接着 Further, the adhesive composition for bonding the confidential surfaces of the pressure-bonded papers is an anion-dispersed system and reacts with the cationic polymer or the polyvalent metal salt to cause agglomeration or remarkable thickening. Further, a large amount of a water-proofing agent is required for making the ink-jet ink manufactured by Cytex Corporation water-resistant, and the water-proofing agent tends to fall off during rework. Therefore, even when a two-layer structure in which a water-resistant agent such as a cationic polymer is undercoated and an overcoat layer of the adhesive composition is provided thereon is used, the water-resistant agent has a reactivity like polyamide epichlorohydrin to cellulose. Unless the resin is a polycation that binds and is insoluble in water, the water-resistant agent of the undercoat layer will fall off during the application of the overcoat layer. Since this is mixed with the return liquid and returned into the adhesive composition, thickening and agglomeration occur, and a coating operation in a short time becomes impossible, so that a die coater in which the measured adhesive composition is poured as an overcoat layer. Unless it is in such a format, it cannot be commercialized.

That is, the cold sealant used for pressure-sensitive adhesive paper is an anionic dispersion system, and when it is mixed with a strong cationic polymer to prepare a one-pack paint suitable for ink-jet pressure-sensitive adhesive paper, the dispersion system is broken, and At the same time as the thickening, the dispersoids that have approached polymerize, forming lumps and becoming unusable as a paint.

The present invention relates to a pressure-sensitive adhesive paper for inkjet, wherein the confidential surfaces of papers having a confidential surface are peelably pressed via an adhesive composition coated on the confidential surface, and a method for producing the same. A cold sealant, a polydimethylamine epichlorohydrin condensate and / or a modified dimethylamine epichlorohydrin condensate. The modified dimethylamine epichlorohydrin condensate is polydimethylamine ammonia epichlorohydrin and polydimethylamine ethylenediamine epichlorohydrin. An inkjet pressure-sensitive adhesive paper coated with a polycation of these polydimethylamine epichlorohydrin and / or modified dimethylamine epichlorohydrin condensate at a solid content of 0.4 to 1.0 g / m ² per side. (Hereinafter, polydimethylamine epichlorohydrin-based polycation is abbreviated as PDMAE.)

In addition, the pressure-sensitive adhesive for inkjet printing contains at least 5 parts by weight of PDMAE per 100 parts by weight of the cold sealant, and the total amount of other polycationic waterproofing agents is 0.4 to 1.0 g / m ² of solid content per side. Pertaining to paper. Also, water-soluble salts of calcium and magnesium can be added for the purpose of saving the amount of polycation processing.

コ ー ル The cold sealant in the adhesive composition is mainly a polymer obtained by polymerizing a natural rubber-based latex and methyl methacrylate and the like, and some of them use an acrylic resin-based emulsion, styrene-butadiene latex or the like. The emulsifier of this natural rubber-based latex is a protein, which is converted into an anionic dispersion by adding a large amount of ammonia. When PDMAEs are added under strong stirring under the condition that the concentration of the cold sealant is 20% or less during the preparation of the paint, the isoelectric point is reached at about 5 parts by weight with respect to the cold sealant, and the viscosity reaches a peak. Beyond this, it is converted to a cationic system, and the viscosity of the system decreases as the amount of PDMAE increases. During this time, it was found that no agglomerates were formed and the viscosity was reduced. Such stable ion return is presumed to be due to the relatively low molecular weight of PDMAEs and the amphoteric dispersant of the latex itself.

The molecular weight of PDMAEs is 10,000 to 100,000, more preferably 10,000 to 30,000, and the cation equivalent is 6.0 to 7.5 meq / g. The molecular weight was determined by high performance liquid chromatography using PEO as a reference substance. The cation equivalent was determined by colloidal titration of 1 g of PDMAE solids with a 1 / 400N polyvinyl potassium sulfate solution, and toluidine 0.1% It is a numerical value obtained by dividing the volume ml (referred to as CV value) at the time of changing from blue to reddish purple by 4 using the solution as an indicator.

PDMAEs may be used as a dispersant for fine mineral powder, or may be added after a cold sealant is added to a dispersion of fine mineral powder with a conventional anionic dispersant in advance. If the PDMAE is less than 5 parts by weight with respect to 100 parts by weight of the cold sealant, the viscosity increases to such an extent that the fluidity is almost lost, and the fluidity comes out at 5 parts by weight or more. It can be seen that the electric point has been reached. Therefore, in practice, it is better to increase the amount to 8 parts by weight and to impart fluidity as completely cationic. When held in this state, rearrangement of the charge of the dispersoid occurs, and the dispersion when the remaining polycation is added is good, and the viscosity is significantly reduced.

Even without such a two-stage addition, when the polycation is continuously mixed, an adhesive coating can be easily obtained without a significant thickening phenomenon, but the viscosity is higher than in the case of the two-stage addition. Slightly higher.

In these cationic adhesive coatings, the viscosity decreases at a practical concentration as the polycation increases with the isoelectric point as a peak, so that the polycation amount can be freely adjusted according to the required water resistance. . In addition, it is possible to save the amount of polycation by using salts of calcium and magnesium having high solubility in water such as hydrochloric acid, sulfuric acid and nitric acid. The present invention is characterized in that the amount of polycations in the adhesive composition when water resistance is the same is small, which is advantageous in maintaining printability during preprinting.

１００ In the adhesive composition, 100 to 250 parts by weight of fine mineral powder is used per 100 parts by weight of the cold sealant. Ultrafine amorphous silica having a particle size of 3 μm or less is optimal as the fine mineral powder. However, since silica itself has a silanol group at the terminal, the silica often reacts with a polycation to increase the viscosity. Mineral powders generally used for coating pigments, such as calcium carbonate, titanium oxide, talc, zeolite, aluminum silicate, calcium silicate, and barium sulfate, are appropriately mixed in consideration of printability. Among these mineral powders, those forming secondary particles are desirably 3 μm or less. This is because the large-diameter secondary particles are apt to collapse due to the linear pressure applied during the pressure bonding, and when the portion overlapping the printed portion of the confidential surface is peeled off, the surface moves to the opposite surface, and the frequency of a transfer accident increases.

The polycations used for the post-addition are polyalkylene polyamine polydiallyl dimethyl ammonium chloride, mineral salts of polyamidoamine (reaction product of polybasic acid or its alkyl ester and polyalkylene polyamine), polyamidoamine epichlorohydrin, 2-propene Amine hydrochloride homopolymer, polyallylamine, allylamine / diallylamine copolymer, polyvinylamine and the like which can be generally used as a water-proofing agent can be used.Other than PDMAEs, polyamidoamine mineral acid salts, polyamidoamine partial epichlorohydrin condensate, 21-propenamine hydrochloride homopolymer and the like are particularly excellent in water resistance. The total amount of polycation applied to the paper is 0.4 to 1.0 g / m ² (solid) per one side, preferably 0.5 to 0.7 g / m ² .

(4) Polyvalent metal salts are effective in insolubilizing dyes, and are particularly useful for forming hydrochloric acid, nitric acid, and sulfate salts of calcium and magnesium by replacing salts in the dyes to form insolubilized dye products. Thereby, the amount of polycation added can be saved.

(4) In the adhesive composition, a pigment dispersant, a pigment adhesive, an antifoaming agent, a pH adjuster, a crosslinking agent for the adhesive, an antioxidant, an antiseptic, and the like may be used as necessary.

This fixing method can be similarly applied to a cationic cold sealant, and an ink jet paint having a particularly low viscosity can be obtained by using PDMAE. In the embodiments, inks manufactured by Cytex Co., Ltd. have been described. However, the present invention can be applied to all water-soluble inks using a direct or acidic dye as a colorant.

According to the present invention, when various types of information are printed on a confidential surface by the ink jet method, the water resistance is good, and even when wet, the printing does not cause bleeding, falling off, contamination, etc., and the preprintability is good. Thus, it is possible to provide an ink jet pressure-bonded paper which also has the performance as a pressure-bonded paper.

Moreover, despite the conversion of anionic paint to cationic paint, it does not generate agglomerates, but becomes a stable and low-viscosity cationic paint, and the polycation can be freely increased or decreased according to the degree of water resistance. It is possible to do. In some cases, salts such as Ca and Mg can be used in combination to help insolubilize the dye. This coating can economically produce the target processed paper regardless of the type of coating as long as uniform lightweight coating is possible.

The present invention will be described more specifically with reference to examples below, but the present invention is not limited to these examples. Parts and% in Examples are parts by weight and% by weight, respectively, unless otherwise noted. The characteristics of PDMAE used in the examples are shown in Table 1 below. In the examples, PDMAE is followed by symbols A to G in accordance with this classification.

<Example 1>
Amorphous silica having a representative particle size of 1.2 μm (Carplex FPS101: manufactured by Shionogi & Co., Ltd.) and 75 parts of talc each having a representative particle size of 2.5 μm are dispersed in water together with an anionic dispersant, and the mixture is dispersed in natural rubber latex (FB). -06FK: manufactured by Mitsui Fuller). To this, 8 parts of PDMAE-F was added. One hour later, as a polycation, 20 parts of PDMAE-G, 15 parts of cationic starch (degree of substitution: 0.15), and 10 parts of magnesium sulfate were added to obtain a paint having a concentration of 28%. This coating material was coated on a high-quality paper with a coating rod so as to have a coating amount of 6 g / m ² .
<Example 2>
It carried out similarly to Example 1 except having used 20 parts of PDMAE-A as a polycation.

<Example 3>
It carried out similarly to Example 1 except having used 20 parts of PDMAE-B as polycation.

<Example 4>
It carried out like Example 1 except having used 20 parts of PDMAE-E as a polycation.

<Example 5>
It carried out like Example 1 except having used 20 parts of PDMAE-D as a polycation.

<Example 6>
It carried out similarly to Example 1 except having used 20 parts of PDMAE-C as polycation.

<Example 7>
The procedure was performed in the same manner as in Example 1, except that 20 parts of a dicyanamide polyalkylene polyamine condensate (Neofix E-117: manufactured by Nichika Chemical) was used as the polycation.

Example 8
The procedure was performed in the same manner as in Example 1 except that as a polycation, 20 parts of a polymer (KJC-S: manufactured by Seiko Chemical Co., Ltd.) obtained by neutralizing polyamidoamine, a reaction product of diethylenetriamine and adipic acid, with sulfuric acid were used.

<Example 9>
The procedure was performed in the same manner as in Example 1 except that 20 parts of 2-propenamine hydrochloride homopolymer (NEOFIX RD-5, manufactured by Nika Chemicals) was used as the polycation.

<Example 10>
Example 1 was repeated except that PDMAE-F as a charge conversion agent was not used and 28 parts of PDMAE was added as a fixing polycation.

<Example 11>
Example 10 was carried out in the same manner as in Example 10, except that 28 parts of PDMAE-A was used as the polycation.

<Example 12>
The same operation as in Example 10 was carried out except that 28 parts of PDMAE-F was used as the polycation.

<Example 13>
Carplex FPS101 and 75 parts each of talc having a representative particle size of 2.5 μm were dispersed in water together with 8 parts of PDMAE-A, and mixed with 100 parts of FB06FK. Immediately, 20 parts of Neofix RD-5, 15 parts of cationic starch, and 10 parts of magnesium sulfate were added to obtain a paint having a concentration of 28%. Hereinafter, it carried out similarly to Example 1.

<Example 14>
Example 13 was carried out in the same manner as in Example 13, except that 8 parts of PDMAE-E was used as a dispersant for the fine mineral powder.

<Example 15>
Carplex FPS101 and 25 parts each of talc having a representative particle size of 2.5 μm were dispersed in water together with an anionic oligomer and mixed with 100 parts of FB06FK. To this, 15 parts of PDMAE-F, 25 parts of PDMAE-C and 15 parts of cationic starch were added to obtain a paint having a concentration of 28%. The viscosity of this paint was measured, and it was applied to a high-quality paper with a coating rod so as to have a solid content of 6 g / m ² .

<Example 16>
Example 15 was carried out in the same manner as in Example 15 except that 20 parts of a polycation to be added later was added as Neofix RD-5.

<Example 17>
In Example 15, it carried out similarly to Example 15 except having added 20 parts of polycation added later as PDMAE-G.

<Comparative Example 1>
Example 1 was repeated except that PDMAE-F as a charge additive was not used and 28 parts of Neofix RD-5 was added as a polycation.

<Comparative Example 2>
It carried out similarly to Example 10 except having used 28 parts of PDMAE-A as a polycation.

According to the above Examples and Comparative Examples, the viscosity of the prepared coating material was measured, and the coating material was coated on a high quality paper with a coating rod so as to have a coating amount of 6 g / m ² . The water resistance of the processed paper with respect to the three color inks of black, blue and red was measured. Hereinafter, each performance test method and a method of evaluation thereof will be described.

(1) Viscosity A paint having a concentration of 28% was measured with a Tokimec B-type viscometer at 60 revolutions. Since the thixotropic property of the paint was large and the viscosity greatly changed depending on the history, the measurement was carried out after a certain period of time from the completion of the preparation as much as possible. A is 50 mPa · s or less, B is 51 to 120 mPa · s, C is 121 to 200 mPa · s, D is 201 to 400 mPa · s. s and E are 401 to 1,000 mPa. s and F are 1,000 mPa · s or more.

(2) Water resistance of printing Ink tanks of # 1007 black, # 1008 blue, and # 1011 red are respectively injected into ink tanks of an inkjet printer (Sharp IO-735X), and solid printing of each color is performed on the bonding surface in a normal mode. went. The printed material was vertically immersed in water at 30 ° C. for 2 minutes, pulled up from the water, attached to a mirror plate, and air-dried so that the material was vertical. The outflow state of the ink in the printed portion of the air-dried material was visually determined and classified into five stages of ◎, ○, ′ ', Δ, and Δ'. ′ 'Is the limit of acceptance, and a slight exudation of the dye is observed at the lower part, and は means that the dots are sharp, no elution of the dye is observed around the print, and the dye is completely fixed.

The results of Examples 1 to 17 and Comparative Examples 1 and 2 are shown in Table 2 below. Except for Examples 15 to 17, the amount of polycation used was 0.5 g / m ² / s.

In Examples 1 to 9, after the charge was reversed with PDMAE-F, the viscosity of the system to which the polycation was added was extremely low. In particular, although the polycation was composed only of PDMAEs, the rate of improvement in water resistance to ink was the highest. .

比較 Comparing Examples 7 and 9 with Comparative Examples 1 and 2, it can be seen that the pretreatment with PDMAE significantly reduces the viscosity and improves the water resistance. Polyamidoamine salts, polyamide epichlorohydrin, and the like can be used in the same formulation. When polyamide epichlorohydrin is used, it has a feature as a water-insoluble dye fixing agent.

１０ In Examples 10 and 12, the required amount of PDMAE was added at one time. At this time, only PDMAE-F has low viscosity but poor fixability, so it is necessary to increase the polycation ratio required for water resistance. A, E, etc., after cationization with F, have higher viscosities and slightly less water resistance than those added.

１３Examples 13 and 14 use A and E of PDMAE for charge reversal, but have higher viscosities than those of FDMA charged reversal, but have almost the same degree of water resistance.

In all of the above examples, an inorganic salt is used in combination. Examples 15 to 17 show systems in which an inorganic salt is not used. When the total amount of polycations is 0.6 to 0.7 g / m ² / s, sufficient water resistance can be achieved.

By mixing 5 parts by weight or more of polydimethylamine epichlorohydrin and / or modified dimethylamine epichlorohydrin condensate with respect to 100 parts by weight of the cold sealant, the anionic dispersion liquid is converted into a cationic liquid, giving fluidity, It is a one-part paint and can be used optimally as an adhesive composition for pressure-sensitive adhesive paper for inkjet.

Claims (2)

In an ink jet pressure-bonded paper, the confidential surfaces of papers having a confidential surface are folded and pressure-bonded so that the confidential surfaces of the papers are peelably adhered to each other via an adhesive composition coated on the confidential surface. Cold sealant, containing polydimethylamine epichlorohydrin condensate and / or modified dimethylamine epichlorohydrin condensate, and blending 5 parts by weight or more of polydimethylamine epichlorohydrin and / or modified dimethylamine epichlorohydrin condensate with 100 parts by weight of the cold sealant Adhesive pressure-sensitive paper for ink-jet, characterized by being made. When producing a press-bonded paper for inkjet, which is folded and press-bonded so that the confidential surfaces of the paper having a confidential surface are peelably adhered to each other via an adhesive composition coated on the confidential surface, the adhesive is used. The composition contains a cold sealant, polydimethylamine epichlorohydrin and / or modified dimethylamine epichlorohydrin condensate, and 5 parts by weight or more of polydimethylamine epichlorohydrin and / or modified dimethylamine epichlorohydrin with respect to 100 parts by weight of the cold sealant. A method for producing a pressure-sensitive adhesive paper for inkjet, comprising mixing a condensate.