JP2007268922A - Contact-bonding postcard paper for inkjet recording - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a contact-bonding postcard paper for inkjet recording with such advantages that an adhesive surface is not sticky, deterioration of release strength due to ultraviolet light and heat, is less significant, water leakage after contact-bonding or paper tear at high humidity, hardly occurs, and the density, water resistance and clarity of an image printed under a rapid rotary press system are excellent. <P>SOLUTION: Not less than two kinds of modified natural rubber derivatives with a differing graft polymerization rate obtained by graft-polymerizing an alkyl ester (meth)acrylate monomer to natural rubber, are mixed in the presence of a nonionic surfactant. Next, an acrylic emulsion with a special glass transition temperature (Tg), is obtained by emulsion-polymerizing a monomer component containing not less than 70 mass% at least one kind selected from the group consisting of a special alkyl ester acrylate and a special alkoxy ethyl ester acrylate, in the presence of a dispersant composed of an alkali neutralization salt of a polymer of a vinylic carboxylic acid or an acid anhydride. Further, an alkylamine epichlorhydrin polycondensation product with a special quaternarization rate, is added as an ink fixing agent to the above mixture and the acrylic emulsion. Thus a pressure-sensitive adhesive is obtained and used for the contact-bonding postcard paper. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention has little deterioration of peel strength due to ultraviolet rays and heat, stably maintains an appropriate peel strength, and does not cause paper tearing or tearing of the base paper material even under wet or high humidity environments after pressure bonding. Furthermore, the present invention relates to a pressure-sensitive postcard paper for ink-jet recording excellent in the print density, water resistance and clearness of an ink-jet recorded image printed by a high-speed rotary system. The pressure-bonded postcard paper described here is a pressure-sensitive adhesive that does not exhibit adhesiveness or adhesiveness under normal conditions, exhibits adhesiveness when pressed, and can be peeled off after pressure bonding (hereinafter referred to as “crimping”). This is a postcard paper having an adhesive layer as a main component provided on a base paper.

In recent years, while the amount of information transmitted by communication means such as communication and postal mail has increased, contact means that require confidentiality such as personal information have been demanded and have been put into practical use. With the revision of the postal code, postcard papers that are cheaper than sealed letters and that can maintain confidentiality of communications as well as sealed letters have been developed and generally spread widely.
This confidential postcard paper is usually printed with UV-curing color ink with standard items (descriptions, precautions, requests, etc.) and then addressed with the toner fixing laser printer method (address of recipient, Name) and personal information (password, membership number, billing amount, deposit balance, etc.) on the adhesive layer, which is a confidential surface, is folded in two (referred to as a four-sided type), or in a tri-fold where a lot of information can be recorded ( Folded to the postcard specification (six-face type) with the confidential surface facing inward, crimped the information so that it can be removed again, concealed the information, and then mailed to remove the part that can be removed again Crimp postcard paper for reading personal information.

  The quality required for such a pressure-bonded postcard paper is as follows: (1) There is little deterioration due to ultraviolet rays by the ultraviolet curable color ink or heat at the time of toner fixing, and the aging stability of the peel strength is excellent. (2) Excellent color ink fillability and printing durability. (3) In the 6-side type specification, there is no stickiness of the adhesive layer surfaces or blocking between the adhesive layer surfaces, and there is no transfer of the adhesive layer to the preheat plate in laser printer printing. (4) No paper tearing or tearing of the paper base material even after peeling in a wet or high humidity environment after pressure bonding. In order to obtain these qualities, selection of main components such as pressure-sensitive adhesives, fine particle fillers, binders, and additives such as anti-degradation agents that form the adhesive layer of base paper and pressure-bonded postcard paper, or design of base paper Is very important.

A specific pressure-sensitive adhesive and its use have been proposed as a measure for preventing deterioration of the adhesive layer due to ultraviolet rays or heat. These suggestions are shown below.
Proposal 1: There is a proposal of a pressure-sensitive adhesive containing 0.1 to 10 parts by weight of a nonionic surfactant having an ethylene oxide addition mole number of 50 to 200 moles relative to 100 parts by weight of modified natural rubber (Patent Document) 1).
Proposal 2: A proposal has been made that an acrylic ester copolymer having a specific glass transition temperature, which is a synthetic rubber, is used as a pressure-sensitive adhesive (see Patent Documents 2, 3, and 4).
Proposal 3: There is a proposal of an adhesive layer using an acrylic ester copolymer which is a pressure-sensitive adhesive (see Patent Document 5).
These proposals are not sufficient. Specifically, natural rubber system is less effective, synthetic rubber system is effective, but when printing with color ink, blanket stains are large and difficult to use alone.When combined with natural rubber, the effect is halved. Not effective.

Conventionally, as pressure-sensitive adhesives, natural rubber derivatives obtained by grafting unsaturated monomers such as methyl methacrylate and styrene on natural rubber have been mainly used.
That is, natural rubber derivatives maintain a high degree of self-adhesion, and when they are brought into contact with each other and applied with pressure, adhesiveness is exhibited, but there is no stickiness, that is, tackiness is low. Grafting increases the polarity of the molecule, increasing the anchoring force against the hydrophilic substance, and preventing the deterioration of self-adhesion due to ultraviolet rays and heat. However, if the grafting rate is high, the untreated peel strength decreases.
If an adhesive layer of natural rubber derivative or synthetic rubber alone is provided on the base paper, it will lack printing suitability such as color ink inking property and printing durability, and the 6-sided type will block the adhesive layers when stored in the wound state. In the case of a toner fixing type laser printer system, glue paste adheres to the preheat plate. In particular, since the synthetic rubber system is inferior, usually, a composition for an adhesive layer is appropriately combined with a fine particle filler represented by kaolin, calcium carbonate, amorphous synthetic silica, and starch particles, and the composition is used as a coating liquid. From the viewpoint of ease of preparation, economy and safety, an adhesive layer is provided by coating with an air knife coater, curtain coater or the like, which is generally an aqueous coating method.

On the other hand, when the postcard paper is wet with rain water during mailing or stored in a high humidity environment, the surface of the paper base and the strength in the paper change, causing paper tearing, paper base tearing, or adhesion. A problem occurs in peeling due to a change in strength of the layer.
Accordingly, measures have been proposed to prevent paper tearing and tearing of the paper base material even when peeled in a high humidity environment. These suggestions are shown below.
Proposal 4: There is a proposal to form or contain a wet paper strength enhancer of 0.5 to 10 g / m ^{2 as} a layer in the base paper surface and / or the adhesive composition on which the adhesive layer is provided (see Patent Document 6). ).
Proposal 5: A water repellent layer is provided between the base paper and the adhesive layer (see Patent Document 7). Alternatively, proposals such as providing a wet paper strength enhancer layer (see Patent Document 8) have been made, but all of them have been found to have a temporary effect, but in recent years, almost complete water resistance has been required. There is a problem.

By the way, as a method for printing on the address side or confidential personal information side of the crimped postcard paper, a water-soluble ink fixing type ink jet printer method capable of printing by a high-speed rotary method has been recently adopted instead of the toner fixing type laser printer method. ing.
As the water-soluble ink to be used, ink # 1000 series, for example, ink of Kodak Versamark (hereinafter referred to as Versamark ink), for example, ink of # 1040 black, # 1069 black, etc. is the most prominent. Versamark ink is characterized in that the solid content of the ink is 4 to 7% by mass, and most of the ink other than the dye is water, and the dielectric constant is excellent. In addition, the solid content of water-soluble ink in general inkjet printers is 15% by mass or more and contains a relatively large amount of non-volatile high-boiling solvent for preventing drying of the ink cartridge head in addition to dye and water. It is very different from rotary ink.

In addition to the quality required for the pressure-sensitive postcard paper for high-speed rotary inkjet recording, (5) the print density of the ink recorded image is high. (6) The water resistance and clearness of the ink recorded image are excellent. (7) Ink absorption during ink printing is fast. (8) The printed image on the confidential surface does not transfer to the opposite surface even after peeling after pressure bonding (hereinafter referred to as ghost prevention). More recently, for example, Versamark ink # 2000 series, specifically, # 2001 cyan, # 2002 magenta, # 2003 black, # 2004 yellow and other full-color ink print density, water resistance and sharpness are important items. It has become.
Ink-fixing and water-proofing technology for ink-jet print images is achieved by containing a cationic polymer that is an ink fixing agent in the composition for the adhesive layer so that the dye molecules in the ink can be charged and charged between the ink and the ink fixing agent. The van der Waals force works to fix the dye molecules to the adhesive layer.

Accordingly, various proposals have been made as cationic polymers that are ink fixing agents. These suggestions are shown below.
Proposal 6: A proposal has been made for a composition for an adhesive layer containing a cationic polymer whose charge changes from zero to negative in a high pH range and a cationic polymer which retains a positive charge, and a polyvalent metal salt. (See Patent Documents 9 and 10). However, these proposals are insufficient for water resistance and sharpness of printed images, particularly for full-color use.
Proposal 7: Proposal of an adhesive layer composition containing polydimethylamine / epichlorohydrin and / or modified dimethylamine / epichlorohydrin polycondensate having a molecular weight of 10,000 to 100,000 and a cation equivalent of 6.0 to 7.5 meq / g. (See Patent Document 11). However, even in this proposal, the water resistance and sharpness of the printed image, particularly the water resistance of full-color magenta ink (# 2002) is insufficient.

Proposal 8: A proposal has been made that 5-100 parts by mass of either a polyamide / epichlorohydrin resin or a water-soluble modified polyamine resin is contained per 100 parts by mass of the natural rubber emulsion (see Patent Document 12). Gelation due to the addition of a cationic polymer during preparation of the adhesive layer coating liquid, water resistance and sharpness, especially water resistance, sharpness and ghost of the full-color ink intended by the present inventors were insufficient. In addition, when the addition amount is increased, there is a problem that the peel strength decreases.
JP 2004-307623 A JP-A-9-194812 JP-A-9-310055 JP-A-11-236544 JP 2001-131503 A JP 2000-103182 A JP 2002-23643 A Japanese Patent No. 3497753 JP-A-9-157611 Japanese Patent Laid-Open No. 10-879 Japanese Patent Application Laid-Open No. 10-52985 JP-A-10-337980

  In the present invention, there is no stickiness on the adhesive layer surface of the pressure-bonded postcard paper, the deterioration of the peel strength due to ultraviolet rays and heat is small, and the appropriate peel strength is stably maintained. Ink-jet pressure bonding with excellent print density, water resistance and sharpness of ink-jet recording images printed by the high-speed rotary method without tearing or tearing of the base paper material, especially excellent water-resistance and sharpness of full-color inks It is to provide postcard paper.

  Adhesive layer composition composed mainly of pressure-sensitive adhesive, fine particle filler, and ink fixing agent that does not show tackiness and adhesiveness under normal conditions and can be peeled off under pressure, is amphoteric polyacrylamide and polyamide epichlorohydrin resin Is a pressure-sensitive adhesive that is a pressure-sensitive adhesive in the presence of a nonionic surfactant to which 50 to 200 mol of ethylene oxide has been added. A modified natural rubber derivative obtained by graft polymerization of a monomer mainly composed of one or more selected from (meth) acrylic acid alkyl ester monomers with respect to 100 parts by mass of rubber in a range of 20 to 60 parts by mass, Two or more kinds of the modified natural rubber derivatives having different graft polymerization rates are mixed, and the vinyl unsaturated monomer in the form of carboxylic acid or acid anhydride is mixed. Acrylic acid alkyl ester having an alkyl group having 1 to 8 carbon atoms and an alkoxy acrylate having an alkoxy group having 1 to 4 carbon atoms in the presence of a dispersant comprising an alkali neutralized salt of a polymer having a monomer as an essential monomer component Ink fixing and pressure-sensitive adhesive containing acrylic emulsion having a glass transition temperature (Tg) of −50 to 0 ° C. obtained by emulsion polymerization of a monomer component containing 70% by mass or more of at least one ethyl ester The object is achieved by the fact that the agent is an alkylamine / epichlorohydrin polycondensate that can have a quaternization rate of 84% or more by a colloid titration method, and the alkylamine / epichlorohydrin polycondensate has a number average molecular weight of 500 to 2000. With the knowledge that a remarkable effect can be obtained on the characteristics of inkjet recording images It has led to the present invention.

  In pressure-sensitive adhesive postcard paper for ink-jet recording, which has been coated with an adhesive layer composition, there is no stickiness on the adhesive layer surface, and the degradation of the peel strength due to ultraviolet rays and heat is minimized, and the proper peel strength is stable. Inkjet recording printed with Versa Mark Ink # 1000, for example, printed with a high-speed rotary method without causing paper tearing or tearing of the base paper material even under wet or high humidity environments after pressing It is possible to provide a pressure-sensitive postcard paper for ink-jet recording excellent in image printing density, water resistance and sharpness, and further excellent in water resistance and sharpness of Versa Mark ink # 2000 series for full color, particularly magenta ink # 2002.

The modified natural rubber derivative used in the present invention is obtained by graft polymerization of 20 to 60 parts by mass of a monomer mainly composed of one or two (meth) acrylic acid alkyl ester monomers with respect to 100 parts by mass of a natural rubber component. Get. Most preferably, it is 25-40 mass parts. If it is less than 20 parts by mass, the effect of preventing ultraviolet rays and heat deterioration is small, and if it exceeds 60 parts by mass, the peel strength decreases.
Specific examples of the alkyl acrylate monomer used in the present invention include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, and decyl acrylate. , Nonyl acrylate, dodecyl acrylate, and the like.

The modified natural rubber derivative used in the present invention is a nonionic surfactant having an ethylene oxide (hereinafter referred to as EO) addition mole number of 50 to 200 moles, preferably 70 to 130 moles per 100 parts by weight of the rubber component. contains. If the added mole number is less than 50 moles, the peel strength is not improved, and if it exceeds 200 moles, no significant effect is obtained.
The conventional modified natural rubber derivative has a greatly reduced peel strength unless one or more selected from (meth) acrylic acid alkyl ester monomers are 25 parts by mass or less with respect to 100 parts by mass of the rubber component. Not practical.
However, the modified natural rubber derivative used in the present invention can prevent a decrease in peel strength by containing a nonionic surfactant to which ethylene oxide is added.

As the nonionic surfactant to which 50 to 200 mol of EO is added, a known one can be used. Specifically, polyoxyethylene nonylphenyl ether which is alkyl allyl ether type; polyoxyethylene lauryl ether which is alkyl ether type; polyoxyethylene lauryl which is alkyl ester type; polyoxyethylene lauryl amine which is alkyl amine type; Examples thereof include polyoxyethylene sorbitan laurate which is a sorbitan derivative type; polyoxyethylene monostyrenated methyl phenyl ether which is a polyoxyethylene styrenated alkylphenyl ether type.
The usage-amount of the nonionic surfactant used for this invention is 0.5-5 mass parts with respect to 100 mass parts of rubber components of a modified natural rubber derivative. If the amount is less than 0.5 parts by mass, no effect can be obtained in improving the peel strength. If the amount exceeds 5 parts by mass, the peel strength decreases.

The acrylic emulsion used in the present invention has 1 to 8 carbon atoms in the presence of a dispersant comprising a polymer alkali neutralized salt containing a vinyl unsaturated monomer in the form of carboxylic acid or acid anhydride as an essential monomer component. A glass obtained by emulsion polymerization of a monomer component containing 70% by mass or more of at least one kind or two or more kinds of acrylic acid alkyl ester having an alkyl group and an alkoxy group having 1 to 4 carbon atoms. It is a polymer having a transition temperature (Tg) of -50 to 0 ° C.
Specific examples of the alkyl acrylate ester having 1 to 8 carbon atoms in the alkyl group include methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. Specific examples of alkoxy alkoxy ester having 1 to 4 carbon atoms of alkoxy include acrylic acid-2-methoxyethyl, acrylic acid-2-ethoxyethyl, and acrylic acid-2-butoxyethyl. In the present invention, acrylic acid alkyl ester and acrylic acid alkoxyethyl ester are used alone or in combination.

In the present invention, as the carbon number of the alkyl group of the acrylic monomer increases, the stickiness of the coated surface tends to increase. From the viewpoint of eliminating the stickiness, alkyl groups such as methyl acrylate, ethyl acrylate and butyl acrylate An alkyl acrylate ester having 1 to 4 carbon atoms is preferred, and ethyl acrylate is particularly preferred.
In the acrylic emulsion used in the present invention, it is necessary to use 70% by mass or more of the above acrylic monomer as a monomer component. In addition to these acrylic monomers, acrylic monomers and A copolymerizable vinyl unsaturated monomer can be used in a range of 30% by mass or less of the total monomer amount.
As the vinyl unsaturated monomer, a non-functional monomer or a monomer having a hydrophilic functional group can be used.
Specific examples of the non-functional monomer used in the present invention include vinyl acetate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, styrene, acrylonitrile and the like. Those homopolymers preferably have a glass transition temperature of 30 ° C. or higher, which reduces the stickiness of the polymer.

Examples of the monomer having a hydrophilic functional group in the vinyl-unsaturated monomers for use in the present invention, specifically acrylic acid, vinyl unsaturation with mosquito carboxyl group such as methacrylic acid, maleic acid and itaconic acid Monomer; vinyl unsaturated monomer having a hydroxyl group such as 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate; vinyl unsaturated monomer having an amide group such as acrylamide and methacrylamide; N-methylolacrylamide, N -Vinyl unsaturated monomer having an N-methylol group such as methylol methacrylamide; Vinyl unsaturated monomer having an amino group such as dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate; Sodium vinyl sulfonate and sodium styrene sulfonate Vinylically unsaturated monomers having a sulfonic acid group, such as 2-acrylamido-2-propane sulfonic acid. Emulsions obtained using these monomers having hydrophilic functional groups can be further stabilized.

When a monomer having a hydrophilic functional group among vinyl unsaturated monomers is used in an amount of preferably 5% by mass or less, particularly preferably 2% by mass or less, based on the total monomer amount, optimum release characteristics can be obtained in an emulsion composition. . Further, in order to eliminate the stickiness and obtain the optimum peel strength, it is preferable to select the monomer component and adjust the glass transition temperature (Tg) of the polymer obtained by emulsion polymerization to -50 to 0 ° C. . If the glass transition temperature (Tg) is less than −50 ° C., the surface of the adhesive layer has a sticky feeling. On the other hand, if it exceeds 0 ° C., the peel strength is very weak, which is not practical.
The acrylic emulsion used in the present invention is a polymer dispersant comprising an alkali neutralized salt of a polymer having the above monomer component as an essential monomer component of a vinyl unsaturated monomer in the form of carboxylic acid or acid anhydride. Below, it is obtained by emulsion polymerization. The polymer dispersant is used as an emulsifier at the time of emulsion polymerization, and further has a cohesive force, and has an effect of enhancing the peel strength at the contact interface between the coated surfaces of the obtained emulsion. Therefore, the acrylic emulsion used in the present invention has a high peel strength, no stickiness, and a balance of peel strength.

As the vinyl unsaturated monomer in the form of carboxylic acid or acid anhydride which is an essential monomer component of the polymer used as the polymer dispersant here, specifically, acrylic acid, methacrylic acid, maleic acid, fumaric acid, Examples thereof include crotonic acid, itaconic acid, maleic anhydride and itaconic anhydride, which are used alone or in combination.
The polymer used as the polymer dispersant in the present invention may be a polymer containing only a vinyl unsaturated monomer in the form of carboxylic acid or acid anhydride as a monomer component, and a vinyl unsaturated monomer and a copolymer thereof may be used. Copolymers containing other possible vinyl unsaturated monomers as monomer components are also possible.
Next, examples of the vinyl unsaturated monomer copolymerizable with the vinyl unsaturated monomer in the form of carboxylic acid or acid anhydride include (meth) acrylic acid alkyl esters such as methyl methacrylate and ethyl acrylate; Hydroxyalkyl (meth) acrylates such as hydroxyethyl acrylate; (meth) acrylamide derivatives such as (meth) acrylonitrile and acrylamide; sulfonic acid monomers such as sodium vinyl sulfonate and sodium styrene sulfonate; dibutyl maleate and Maleic acid esters such as dioctyl maleate; vinyl acetate and styrene.

The polymer used as a polymer dispersant having excellent stability during emulsion polymerization and excellent stability of the resulting emulsion has an acid value of 200 or more and a number average molecular weight of preferably 400 to 10,000.
Further, among the polymers having a vinyl unsaturated monomer in the form of carboxylic acid or acid anhydride as an essential component, preferred in the present invention are specifically polyacrylic acid, polymethacrylic acid, (meth) Acrylic acid / (meth) acrylic acid alkyl ester copolymer, (meth) acrylic acid / styrene copolymer, (meth) acrylic acid / (meth) acrylic acid alkyl ester / styrene copolymer and styrene / maleic anhydride copolymer A polymer etc. are mentioned.

Polymers of vinyl unsaturated monomers essential monomeric components in the form of a carboxylic acid or acid anhydride, for example in water, in a mixture of a hydrophilic organic solvent or a hydrophilic organic solvent, using a radical polymerization initiator And obtained by polymerizing the above monomers.
Specific examples of the hydrophilic organic solvent used in the present invention include alcohols such as methyl alcohol, ethyl alcohol and isopropyl alcohol; ketones such as acetone and methyl ethyl ketone; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, And glycol ethers such as ethylene glycol monobutyl ether and propylene glycol monomethyl ether.
Specific examples of the radical polymerization initiator used in the present invention include persulfates such as ammonium persulfate and potassium persulfate; 2,2-azobisisobutyronitrile, 2,2-azobis (2,4-dimethyl). Azo type such as valeronitrile); peroxide type such as t-butyl hydroperoxide, benzoyl peroxide and lauroyl peroxide.
The usage-amount of the radical polymerization initiator used for this invention is 0.2-10 mass parts with respect to 100 mass parts of superposition | polymerization all monomers, Preferably it is 0.5-5 mass parts.
The reaction temperature during the polymerization is 50 to 120 ° C., and the reaction time is 1 to 16 hours, preferably 2 to 8 hours.

Since the used organic solvent acts as a chain transfer agent when an acrylic emulsion is obtained by emulsion polymerization, it is preferably distilled off after polymerization by raising the temperature and reducing the pressure.
The carboxyl group contained in the polymer containing a vinyl unsaturated monomer in the form of carboxylic acid or acid anhydride as an essential monomer component is neutralized partially or entirely, and polymer dispersed in the form of an alkali neutralized salt. Used as an agent. Specific examples of the alkali compound used in the present invention include amine compounds such as monoethylamine, diethylamine, triethylamine, monoethanolamine, dimethylaminoethanol and morpholine; inorganic alkali compounds such as ammonia, sodium hydroxide and potassium hydroxide. Can be mentioned. If the degree of neutralization is 30 to 100%, the hydrophilicity is sufficient and a stable emulsion can be obtained.
The usage-amount of the polymer dispersing agent used by this invention is 0.1-5.0 mass parts with respect to 100 mass parts of all monomers, Preferably it is 0.2-2.5 mass parts.

In the present invention, at the time of emulsion polymerization, the polymer dispersant is mixed with a known emulsifier used in ordinary emulsion polymerization. Examples of the emulsifier used in the present invention include anionic, nonionic, cationic and amphoteric emulsifiers. Specifically, anionic emulsifiers include potassium oleate, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, Sodium alkane sulfonate, sodium alkyl naphthalene sulfonate, sodium dialkyl sulfo succinate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl allyl ether sulfate, polyoxyethylene alkyl ether phosphate, polyoxyethylene alkyl allyl ether phosphate, etc. Is mentioned.
Examples of the nonionic emulsifier include polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene oxypropylene block polymer, polyethylene glycol fatty acid ester and polyoxyethylene sorbitan fatty acid ester.

Examples of the cationic emulsifier include stearylamine hydrochloride, lauryltrimethylammonium chloride, and trimethyloctadecylammonium chloride.
Examples of amphoteric emulsifiers include lauryl betaine and lauryl dimethylamine oxide.

Here, an example of known emulsion polymerization, which is a method for producing an acrylic emulsion essential in the present invention, is shown.
A monomer and a polymerization initiator are continuously added at a predetermined temperature while stirring in an aqueous medium to which a polymer dispersant alone or a polymer dispersant and an emulsifier are added. Monomer is added alone or in the form of a monomer emulsion with water and an emulsifier. The monomer concentration is 30 to 70% by mass, preferably 35 to 65% by mass, based on the total amount of charge.

  The mixing ratio of two kinds of modified natural rubber derivatives having different graft polymerization rates and acrylic emulsions used in the present invention is specifically a nonionic surfactant added with specific ethylene oxide to 100 parts by mass of natural rubber. And a modified natural rubber derivative (a) obtained by graft polymerization of 20 to 35 parts by mass of (meth) acrylic acid alkyl ester, and a nonionic surfactant having a specific ethylene oxide added to 100 parts by mass of natural rubber. Furthermore, the mixing ratio of the modified natural rubber derivative (b) obtained by graft polymerization of 36 to 60 parts by mass of (meth) acrylic acid alkyl ester and the acrylic emulsion (c) is (a) :( b) :( c) = 20-60 parts by mass: 25-50 parts by mass: 10-40 parts by mass.

  When (a) is less than 20 parts by mass, and (b) is less than 25 parts by mass, the effect of preventing ultraviolet rays and heat deterioration is small, (a) exceeds 60 parts by mass, and (b) exceeds 50 parts by mass. , Peeling strength decreases. If (c) is less than 10 parts by mass, the paper tears and the base paper material breaks in a high humidity environment, and if it exceeds 40 parts by mass, blanket stains occur during color ink printing, resulting in poor printing durability.

  Specific examples of the alkylamine / epichlorohydrin polycondensate that can have a quaternization rate of 84% or more by the colloid titration method used in the present invention include dimethylamine / epichlorohydrin polycondensate, diethylamine / epichlorohydrin polycondensate, dipropylamine.・ Epichlorohydrin polycondensate, dibutylamine / epichlorohydrin polycondensate, methylethylamine / epichlorohydrin polycondensate, methylpropylamine / epichlorohydrin polycondensate, methylbutylamine / epichlorohydrin polycondensate, ethylpropylamine / epichlorohydrin polycondensate, ethylbutylamine -1 type or 2 or more types of epichlorohydrin polycondensates are contained, Especially preferably, it is a dimethylamine epichlorohydrin polycondensate.

The number average molecular weight of the alkylamine / epichlorohydrin polycondensate used in the present invention is preferably 500 to 2000, and particularly preferably 800 to 1500.
The quaternization rate of the alkylamine / epichlorohydrin polycondensate used in the present invention by the colloid titration method is 84% or more, particularly preferably 95% or more.
If it is less than 84%, the water resistance of cyan ink # 2001 and magenta ink # 2002 in the 2000 series of inks is particularly poor.

The quaternization rate referred to in the present invention is a colloidal titration of a 1 / 400N alkylamine / epichlorohydrin polycondensate with a standard polyanion, 1 / 400N potassium potassium sulfate solution, and a cationic dye, toluidine blue 0.1% solution. The milliequivalent / g is calculated from the titration value at the time of changing from blue to reddish purple as an indicator.
Since the surface charge of the colloid changes depending on the pH, in the present invention, colloid equivalents of pH 4 and pH 10 are obtained, and the quaternization rate is obtained as [pH 10 / pH 4 × 100]. use.
The cationic polymer used for this invention is 5-70 mass parts with respect to 100 mass parts of pressure sensitive adhesives, Preferably it is 10-50 mass parts. If the amount is less than 5 parts by mass, the water resistance effect is small.

  Examples of the fine particle filler used in the present invention include talc, kaolin, calcined kaolin, acidic clay, activated clay, amorphous synthetic silica, colloidal silica, colloidal alumina, zeolite, calcium carbonate, magnesium carbonate, titanium dioxide, zinc oxide. , Aluminum hydroxide, corn starch, potato starch, wheat starch, urea formalin resin, polyethylene resin, polystyrene resin, etc. are used, and one or a mixture of two or more types is used, and particularly preferably excellent in blocking prevention and printability. Furthermore, it is amorphous synthetic silica having a fast ink absorption and corn starch, wheat starch or titanium dioxide having high opacity, which is excellent in roll stain prevention and foam processing suitability.

  The binder for the fine particle filler used in the present invention is preferably a water-soluble polymer or a hydrophobic polymer latex. Examples of the water-soluble polymer include starch, casein, soy protein, gelatin, polyvinyl alcohol and derivatives thereof. As the hydrophobic polymer latex, for example, an acrylic latex that is a copolymer of an acrylate ester and methyl methacrylate or styrene. Vinyl acetate latex which is a copolymer of vinyl acetate and acrylic acid ester or maleic acid ester. A vinylidene chloride latex which is a copolymer of vinylidene chloride and methyl acrylate, acrylonitrile or vinyl chloride. Examples of the styrene butadiene latex include styrene and butadiene as main constituent monomers. Polyvinyl alcohol and derivatives thereof having excellent binding power, and styrene butadiene latex are preferable.

If desired, the composition for an adhesive layer of the present invention can achieve an intended function by appropriately mixing auxiliary agents such as an antistatic agent, a fluorescent brightening agent, a preservative, an antifoaming agent, a penetrating agent, and a coloring dye.
The pressure-sensitive postcard paper for ink jet recording of the present invention is provided on one side or both sides of a base paper using the composition for an adhesive layer of the present invention as a coating liquid. The base paper used in the present invention is composed mainly of wood pulp, a fine filler for filling, and a paper strength enhancer. Wood pulp includes chemical pulp such as LBKP and NBKP; mechanical pulp such as GP, PGW, RMP, TMP, CTMP, and CGP; waste paper recycled pulp such as DIP. These pulps are suitable for papermaking and coating. Adjusts the beating degree (freeness) with a beater to maintain printability.
The beating degree varies depending on the type of pulp, but is generally 150 to 500 ml [Canadian Standard Freeness (hereinafter referred to as CSF): JIS P-8121].
In order to maintain the ink absorbability improvement, opacity, and printability, the inner fine particle filler includes, for example, talc, calcined kaolin, calcium carbonate, titanium dioxide, and the mixing ratio is based on 100 parts by mass of the pulp. It is 5-30 mass parts, Preferably it is 10-20 mass parts.
Furthermore, in order to maintain the water resistance of the base paper for the purpose of preventing paper tearing and tearing of the base paper material even under wet or high humidity environments, conventionally known sizing agents, yield improvers, cationizing agents Mix various additives such as paper strength enhancer. In particular, a paper strength enhancer is preferable, and specific examples include melamine resin, urea resin, polyacrylamide, polyamide / epichlorohydrin resin, melamine / formaldehyde resin, etc. Acidic, neutral, and alkaline base paper is obtained with a circular paper machine, twin wire paper machine, and the like.

Examples of the method for providing the adhesive layer composition of the present invention on one side of a base paper include a blade coater, an air knife coater, a curtain coater, a bar coater, a gravure coater, a roll coater, a bill blade coater, a gate roll coater, a transfer roll coater, and the like. With this coating method, an adhesive layer is provided on one side of the base paper so that the coating amount is 1.5 to 10 g / m ² (dry mass solid content), and further suitable for printer printing, color ink In order to improve printability, the surface of the adhesive layer is processed with a smoothing device such as a super calender or soft calender so that the smoothness of the surface of the adhesive layer is 20 to 40 seconds in Beck-type smoothness, and the crimped postcard paper for bi-fold inkjet recording Get.

Alternatively, the adhesive layer composition may be provided on both sides of the base paper by coating a blade coater, air knife coater, curtain coater, bar coater, gravure coater, roll coater, bill blade coater, gate roll coater, transfer roll coater, etc. Coating on one side of the base paper and then on the other side in the construction method (so that a separation balance on both sides can be obtained) with a single-side coating amount of 1.5 to 10 g / m ² (dry mass solid content) After drying, an adhesive layer is provided, and in the same manner as described above, the surface of the adhesive layer is smoothed by a smoothing device such as a super calender or soft calender so that the smoothness of the surface of the adhesive layer is 20 to 40 seconds, and is folded in three. A pressure-sensitive postcard paper for ink jet recording is obtained.

  The preferred embodiments of the present invention and the excellent effects thereof will be specifically described below with the most representative examples. In the following, all parts are parts by mass, and all% are% by mass.

Example 1
[Trifold (double-sided coating) Preparation of pressure-sensitive postcard for inkjet recording]
LBKP (CSF 300 ml) 100 parts Talc 20 parts 50% rosin size emulsion 3.4 parts 50% sulfuric acid band aqueous solution 5 parts 4% amphoteric polyacrylamide aqueous solution 3.8 parts 25% polyamide / epichlorohydrin resin 1.5 parts 1% of the above composition After the slurry is made with a long paper machine, a size press is performed with a 6% aqueous solution of oxidized starch (manufactured by Nippon Shokuhin Kako Co., Ltd .: MS-3800) so that the double-sided adhesion is 1.2 g / m ² (dry mass solid content). A base paper for pressure proof postcards for tri-fold ink jet recording that is resistant to tearing and tearing even in a high humidity environment with a basis weight of 113 g / m ² was obtained.

[Production of 20% modified natural rubber emulsion (1)]
Prepare a monomer emulsion (I) by stirring and dispersing 20 parts of water, 5 parts of polyoxyethylene tridecyl ether type nonionic surfactant (EO added mole number 70 moles) and 20 parts of methyl methacrylate in a separate container in advance. did.
Next, 167 parts of 60% natural rubber emulsion (substantially solid content 100 parts) and 24 parts of water were added to the reaction vessel and the temperature was increased to 40 ° C. while stirring and the monomer emulsion (a), 3 51% solid content denatured by 20% by adjusting water content appropriately after gradually dropping 10 parts of 3% aqueous solution of t-butyl hydroperoxide and 15 parts of 3% tetraethylenepentamine aqueous solution, aging and cooling to room temperature A natural rubber emulsion of concentration (1) was obtained.

[Production of 60% modified natural rubber emulsion (2)]
20% modified 51% solid content natural rubber emulsion-(1) Replace 20 parts of methyl methacrylate, which is the material of the monomer emulsion (a) at the time of preparation, with 10 parts of methyl acrylate and 50 parts of methyl methacrylate. A natural rubber emulsion (51) having a solid content concentration of 51%, which was modified 60% by appropriately adjusting the amount of water by the same method except that the monomer emulsion (b) was prepared, was obtained.

[Preparation of Acrylic Emulsion-A]
A monomer emulsion (a) composed of 225 g of water, 500 g of ethyl acrylate, and 6.5 g of a reactive emulsifier (Eleminol JS-2: manufactured by Sanyo Chemical Industries) was prepared in a separate container in advance.
Next, 150 g of water, 12.5 g of 30% polymethacrylic acid (number average molecular weight 650, acid value 652) as a polymer dispersant, and 2.5 g of 25% ammonia water were added to the reaction vessel, and the temperature was raised to 60 ° C. It was.
Further, while stirring, 12 g of 10% ammonium persulfate aqueous solution and the monomer emulsion (a) prepared above were gradually added dropwise, and after aging and cooling to room temperature, the water content was adjusted as appropriate to adjust the glass transition temperature (Tg) − An acrylic emulsion A having a solid content concentration of 19 ° C. and 55% solid was obtained.

[Production of tri-fold (double-sided coating) pressure-sensitive postcard paper for inkjet recording]
While stirring 550 parts of the prepared water, 16 parts of a 25% aqueous sodium hydroxide solution (mass solid content 4 parts), 70 parts of amorphous synthetic silica powder (Mizusawa Chemical Industry: Mizukasil P78D), amorphous synthetic silica powder ( 70 parts of Mizusawa Chemical Industries: Mizukasil P78F) and 10 parts of wheat starch powder (Glyco Nutrition Foods: 75A) are gradually added and dispersed.
Subsequently, 107.8 parts (55 parts by mass solid content) of the 20% modified 51% natural rubber emulsion (1) obtained above and 49.0 parts (60) modified 51% natural rubber emulsion (2) ( (Mass solid content 25 parts), 55% acrylic emulsion-A 36.4 parts (mass solid content 20 parts), quaternization rate 84% and number average molecular weight 2000, dimethylamine / epichlorohydrin polycondensate 50% aqueous solution 100 10 parts polyvinyl alcohol aqueous solution 20 parts (mass solid content 2 parts), 50% styrene butadiene copolymer latex 60 parts (mass solid content 30 parts) was gradually added, and then diluted water Was adjusted to a 25.0% solid content concentration to obtain a coating solution for an adhesive layer for inkjet recording.

Next, the coating amount for the adhesive layer was coated on one side of the 113 g / m ² base paper prepared above, and the coating amount was 6.8 g / m ² (dry mass solid content), and then the coating amount on the other side was 6.5 g. / M ² (dry mass solid content) is coated and dried with an air knife coater so as to obtain a peel strength balance on both sides, an adhesive layer is provided, and then a soft calender with a Beck smoothness of 25 to 35 seconds. A tri-fold ink jet pressure-bonded postcard paper was obtained.

Example 2
[Production of 35% modified natural rubber emulsion (3)]
20% modified 51% natural rubber emulsion of Example 1-(1) 20 parts of methyl methacrylate, which is the material of the monomer emulsion (i) at the time of preparation, 10 parts of methyl acrylate, 15 parts of butyl acrylate, methacrylic A 51% solid content natural rubber emulsion (3) modified by 35% was obtained in the same manner as in Example 1 except that the monomer emulsion (c) was prepared by stirring and dispersing in place of 10 parts of methyl acid. It was.

[Production of 40% modified natural rubber emulsion (4)]
20% modified 51% natural rubber emulsion of Example 1-(1) 20 parts of methyl methacrylate, which is the material of the monomer emulsion (i) at the time of preparation, 10 parts of methyl acrylate, 20 parts of butyl acrylate, methacrylic acid A 51% solid content natural rubber emulsion (4) modified by 40% was obtained in the same manner as in Example 1 except that the monomer emulsion (d) was prepared by stirring and dispersing in place of 10 parts of methyl. .

[Preparation of acrylic emulsion-B]
Monomer emulsification consisting of 225 g of water, 490 g of ethyl acrylate, 12.5 g of 80% acrylic acid, 9.5 g of 25% aqueous ammonia, and 2.5 g of reactive emulsifier (Aqualon HS-10, manufactured by Daiichi Kogyo Seiyaku) in a separate container. A liquid (b) was produced.
Next, 150 g of water, 2.5 g of 30% methacrylic acid / butyl acrylate copolymer (number average molecular weight 4200, acid value 456), which is a polymer dispersant, and 5.0 g of 25% ammonia are charged into the reaction vessel. The temperature was raised to ° C.
Further, 12 g of a 10% ammonium persulfate aqueous solution and the monomer emulsion (b) prepared above were gradually added dropwise with stirring, after aging and cooling to room temperature, the water content was adjusted as appropriate, and the glass transition temperature (Tg) -17. An acrylic emulsion-B having a solid content concentration of 55 ° C. was obtained.

[Production of tri-fold (double-sided coating) pressure-sensitive postcard paper for inkjet recording]
Number average molecular weight of 20% modified 51% natural rubber emulsion of Example 1 (1), 60% modified 51% natural rubber emulsion (2) and 55% acrylic emulsion A and quaternization rate of 84% 51% natural rubber emulsion modified with 35% of a 50% aqueous solution of 2000 dimethylamine / epichlorohydrin polycondensate (7) (3) 78.4 parts (mass solid content 40 parts), 51% natural rubber emulsion modified 40% (4) ) 68.6 parts (mass solid content 35 parts), 55% acrylic emulsion-B 45.5 parts (mass solid content 25 parts) and quaternization rate 99%, number average molecular weight 300, dimethylamine / epichlorohydrin polycondensate A crimped postcard paper for tri-fold ink jet recording was obtained in the same manner except that it was replaced with 100 parts of a 50% aqueous solution.

Example 3
[Production of 25% modified natural rubber emulsion (5)]
20% modified natural rubber emulsion of Example 1 (1) Polyoxyethylene tridecyl ether type nonionic surfactant 5 parts and methyl methacrylate 20 parts which are the raw materials of the monomer emulsion (i) at the time of preparation Oxyethylene higher alcohol ethoxylate-type nonionic surfactant (EO added mole number 100 moles) 1.4 parts methyl acrylate 10 parts, methyl methacrylate 15 parts stirring and dispersing monomer emulsion (e) A natural rubber emulsion (51) having a solid content concentration of 51% with 25% modification was obtained by appropriately adjusting the amount of water in the same manner as in Example 1 except that the above was prepared.

[Production of 40% modified natural rubber emulsion (6)]
20% modified natural rubber emulsion of Example 1 (1) Polyoxyethylene tridecyl ether type nonionic surfactant 5 parts and methyl methacrylate 20 parts which are the raw materials of the monomer emulsion (i) at the time of preparation Oxyethylene higher alcohol ethoxylate-type nonionic surfactant (EO added mole number 100 moles) 1.4 parts, methyl acrylate 10 parts, methyl methacrylate 30 parts A 51% solid content natural rubber emulsion (6) was obtained by appropriately adjusting the amount of water in the same manner as in Example 1 except that was prepared.

[Preparation of Acrylic Emulsion-C]
To the reaction vessel, 383.3 g of water and 41.7 g of 30% acrylic acid / ethyl acrylate copolymer (number average molecular weight 2800, acid value 234) as a polymer dispersant were added and the temperature was raised to 60 ° C.
Further, 12 g of 10% ammonium persulfate aqueous solution and 500 g of ethyl acrylate were gradually added dropwise with stirring, and then aged and cooled to room temperature. Acrylic emulsion-C having a glass transition temperature (Tg) of -19 ° C. and 55% solid content concentration Got.

[Production of tri-fold (double-sided coating) pressure-sensitive postcard paper for inkjet recording]
Number average molecular weight of 20% modified 51% natural rubber emulsion of Example 1 (1), 60% modified 51% natural rubber emulsion (2) and 55% acrylic emulsion A and quaternization rate of 84% 25% modified 51% natural rubber emulsion of 2000% dimethylamine / epichlorohydrin polycondensate 50% aqueous solution-(5) 78.4 parts (mass solid content 40 parts), 40% modified 51% natural rubber emulsion-(6 ) 78.4 parts (mass solid content 40 parts), 55% acrylic emulsion-C 36.4 parts (mass solid content 20 parts) and quaternization rate 99%, number average molecular weight 3000, dimethylamine / epichlorohydrin polycondensate A crimped postcard paper for tri-fold ink jet recording was obtained in the same manner except that it was replaced with 100 parts of a 50% aqueous solution.

Example 4
[Production of 25% modified natural rubber emulsion (7)]
25% modified natural rubber emulsion of Example 3 (5) 1.4 parts of polyoxyethylene higher alcohol ethoxylate type nonionic surfactant which is the material of the monomer emulsion (e) at the time of preparation was polyoxyethylene nonyl 25% modification in the same manner as in Example 1 except that the monomer ether emulsion (g) was prepared by stirring and dispersing in place of 0.5 part of phenyl ether type nonionic surfactant (EO addition mole number 130 mol). A natural rubber emulsion (7) having a solid concentration of 51% was obtained.

[Production of tri-fold (double-sided coating) pressure-sensitive postcard paper for inkjet recording]
Number average molecular weight of 20% modified 51% natural rubber emulsion of Example 1 (1), 60% modified 51% natural rubber emulsion (2) and 55% acrylic emulsion A and quaternization rate of 84% 25% modified 51% natural rubber emulsion of 2000% dimethylamine / epichlorohydrin polycondensate 50% aqueous solution-(7) 78.4 parts (mass solid content 40 parts), 40% modified 51% natural rubber emulsion-(4 ) 78.4 parts (mass solid content 40 parts) and 55% acrylic emulsion-C 36.4 parts (mass solid content 20 parts) and a quaternization rate 99% and a number average molecular weight of 500 and a number average molecular weight of 500 dimethylamine / epichlorohydrin polycondensate A crimped postcard paper for tri-fold ink jet recording was obtained in the same manner except that it was replaced with 100 parts of a 50% aqueous solution.

Example 5
[Preparation of acrylic emulsion-D]
The monomer emulsion (c) was prepared by replacing 500 g of ethyl acrylate, which is the material of the monomer emulsion (a) at the time of preparation of the acrylic emulsion-A of Example 1, with 250 g of methyl acrylate and 250 g of ethyl acrylate. In the same manner, an acrylic emulsion-D having a glass transition temperature (Tg) of -6 ° C. and a solid content concentration of 55% was obtained.

[Production of tri-fold (double-sided coating) pressure-sensitive postcard paper for inkjet recording]
A crimped postcard paper for tri-fold ink jet recording was obtained in the same manner except that the same amount of 55% acrylic emulsion-A in Example 1 was replaced with 55% acrylic emulsion-D.

Example 6
[Preparation of acrylic emulsion-E]
Similar to Example 1, except that 500 g of ethyl acrylate, which is the material of the monomer emulsion (a) at the time of preparation of the acrylic emulsion-A, was replaced with 475 g of butyl acrylate and 25 g of acrylonitrile to prepare a monomer emulsion (d). By the method, an acrylic emulsion-E having a glass transition temperature (Tg) of −47 ° C. and a solid content concentration of 55% was obtained.

[Production of tri-fold (double-sided coating) pressure-sensitive postcard paper for inkjet recording]
A crimped postcard paper for tri-fold inkjet recording was obtained in the same manner except that the same amount of 55% acrylic emulsion-A in Example 1 was replaced with 55% acrylic emulsion-E.

Example 7
[Production of 20% modified natural rubber emulsion (8)]
20 % modified natural rubber emulsion of Example 1 (1) Polyoxyethylene tridecyl ether type nonionic surfactant, which is a raw material of the monomer emulsion (i) at the time of preparation, is polyoxyethylene nonylphenyl ether type nonionic A 51% natural rubber emulsion (8) modified by 20% was obtained in the same manner except that the same amount was replaced with a surfactant (EO added mole number 50 moles) to prepare a monomer emulsion (h).

[Production of tri-fold (double-sided coating) pressure-sensitive postcard paper for inkjet recording]
Crimped postcard paper for tri-fold inkjet recording in the same manner except that the same amount of 20% modified 51% natural rubber emulsion of Example 1 (1) was replaced with 20% modified 51% natural rubber emulsion (8). Got.

Example 8
[Production of 25% modified natural rubber emulsion (9)]
25% modified 51% natural rubber emulsion of Example 4 (7) 130 mol of EO addition mole of polyoxyethylene nonylphenyl ether type nonionic surfactant which is a material of monomer emulsion (g) at the time of preparation A 51% natural rubber emulsion (9) modified by 25% was obtained in the same manner as in Example 1 except that the amount added was changed to 200 mol and the same amount was replaced to prepare a monomer emulsion (Li).

[Production of tri-fold (double-sided coating) pressure-sensitive postcard paper for inkjet recording]
Crimped postcard paper for tri-fold inkjet recording in the same manner except that the same amount of 25% modified 51% natural rubber emulsion (7) in Example 4 was replaced with 25% modified 51% natural rubber emulsion (9). Got.

Comparative Example 1
[Production of 20% modified natural rubber emulsion (10)]
20 Modified Natural Rubber Emulsion of Example 1-(1) Polyoxyethylene tridecyl ether type nonionic surfactant which is a raw material of the monomer emulsion (i) at the time of preparation is changed to polyoxyethylene nonylphenyl ether type nonionic interface A 51% natural rubber emulsion (10) modified by 20% was obtained by the same method except that the same amount was replaced with the activator (EO addition mole number 30 mol) to prepare a monomer emulsion (nu).

[Trifold (double-sided coating) production of pressure-sensitive postcard paper for inkjet recording]
Crimped postcard paper for tri-fold ink jet recording by the same method except that the same amount of 20% modified 51% natural rubber emulsion of Example 1 (1) was replaced with 20% modified 51% natural rubber emulsion (10). Got.

Comparative Example 2
[Production of 25% modified natural rubber emulsion (11)]
25% modified 51% natural rubber emulsion of Example 4 (7) Polyoxyethylene nonylphenyl ether type nonionic surfactant which is a raw material of monomer emulsion (g) at the time of preparation was changed to lauryl ether sulfate sodium salt type anion A 51% natural rubber emulsion (11) modified by 25% was obtained in the same manner as in Example 1 except that the monomer emulsion (L) was prepared by replacing the same amount with the surfactant.

[Production of tri-fold (double-sided coating) pressure-sensitive postcard paper for inkjet recording]
Crimped postcard paper for tri-fold ink jet recording in the same manner as in Example 4, except that the same amount of 25% modified 51% natural rubber emulsion (7) was replaced with 25% modified 51% natural rubber emulsion (11). Got.

Comparative Example 3
[Production of 15% modified natural rubber emulsion (12)]
20% modified natural rubber emulsion of Example 1-(1) Monomer emulsion (O) was prepared by replacing 20 parts of methyl methacrylate, which is the material of the monomer emulsion (I) at the time of preparation, with 15 parts of methyl methacrylate. A 51% natural rubber emulsion (12) modified by 15% was obtained in the same manner as described above.

[Production of tri-fold (double-sided coating) pressure-sensitive postcard paper for inkjet recording]
Crimped postcard paper for tri-fold ink jet recording in the same manner except that the same amount of 25% modified 51% natural rubber emulsion of Example 4 (7) was replaced with 15% modified 51% natural rubber emulsion (12). Got.

Comparative Example 4
[Production of 70% modified natural rubber emulsion (13)]
60% modified natural rubber emulsion of Example 1 (2) Monomer emulsification by replacing 10 parts of methyl acrylate and 50 parts of methyl methacrylate, which are raw materials of the monomer emulsified liquid (b) at the time of preparation, with 70 parts of methyl methacrylate A 51% natural rubber emulsion (13) modified by 70% was obtained in the same manner except that the liquid (wa) was produced.

[Trifold (double-sided coating) production of pressure-sensitive postcard paper for inkjet recording]
Crimped postcard paper for tri-fold ink jet recording in the same manner as in Example 1, except that the same amount of 60% modified 51% natural rubber emulsion (2) was replaced with 70% modified 51% natural rubber emulsion (13). Got.

Comparative Example 5
[Preparation of acrylic emulsion-F]
Monomer emulsion (e) consisting of 225 g of water, 490 g of ethyl acrylate, 12.5 g of 80% acrylic acid, and 10 g of polyoxyethylene nonylphenyl ether sulfate ammonium salt (Eleminol ES-70: manufactured by Sanyo Chemical Industries) in a separate container. Was made.
Next, 150 g of water and 10 g of polyoxyethylene nonylphenyl ether (Nonipol 200: manufactured by Sanyo Chemical Industries) were added to the reaction vessel and the temperature was raised to 60 ° C.
Further, with stirring, 12 g of 10% ammonium persulfate aqueous solution and the monomer emulsion (e) prepared above were added dropwise, then aged and cooled to room temperature, and a glass transition temperature (Tg) of -17 ° C. and 55% solids concentration acrylic. System Emulsion-F was obtained.

[Production of tri-fold (double-sided coating) pressure-sensitive postcard paper for inkjet recording]
A crimped postcard paper for tri-fold inkjet recording was obtained in the same manner except that the same amount of 55% acrylic emulsion-A in Example 1 was replaced with 55% acrylic emulsion-F.

Comparative Example 6
[Preparation of acrylic emulsion-G]
Glass in the same manner except that the monomer emulsion (f) was prepared by replacing the same amount of ethyl acrylate as the material of the monomer emulsion (a) at the time of preparation of the acrylic emulsion-A of Example 1 with methyl acrylate. A 55% solid content acrylic emulsion-G having a transition temperature (Tg) + 8 ° C. was obtained.

[Production of tri-fold (double-sided coating) pressure-sensitive postcard paper for inkjet recording]
A crimped postcard paper for tri-fold inkjet recording was obtained in the same manner except that the same amount of 55% acrylic emulsion-A in Example 1 was replaced with 55% acrylic emulsion-G.

Comparative Example 7
[Preparation of acrylic emulsion-H]
Glass in the same manner except that the monomer emulsion (g) was prepared by replacing the same amount of ethyl acrylate as the material of the monomer emulsion (a) used in the preparation of the acrylic emulsion-A in Example 1 with butyl acrylate. A 55% solid content acrylic emulsion-H having a transition temperature (Tg) of −52 ° C. was obtained.

[Production of tri-fold (double-sided coating) pressure-sensitive postcard paper for inkjet recording]
A crimped postcard paper for tri-fold inkjet recording was obtained in the same manner except that the same amount of 55% acrylic emulsion-A in Example 1 was replaced with 55% acrylic emulsion-H.

Comparative Example 8
[Production of tri-fold (double-sided coating) pressure-sensitive postcard paper for inkjet recording]
20% modified 51% natural rubber emulsion as pressure sensitive adhesive of Example 1 (1) 107.8 parts, 60% modified 51% natural rubber emulsion (2) 49.0 parts, 55% acrylic Emulsion-A 36.4 parts, 60% modified 51% natural rubber emulsion-Excluding (2), 20% modified 51% natural rubber emulsion- (1) 156.8 parts (mass solid content 80 parts) A crimped postcard paper for tri-fold ink jet recording was obtained in the same manner except that the amount was increased.

Comparative Example 9
[Production of tri-fold (double-sided coating) pressure-sensitive postcard paper for inkjet recording]
20% modified 51% natural rubber emulsion as pressure sensitive adhesive of Example 1 (1) 107.8 parts, 60% modified 51% natural rubber emulsion (2) 49.0 parts, 55% acrylic Emulsion-A 36.4 parts, 51% natural rubber emulsion modified by 20%, except for (1), 51% natural rubber emulsion modified by 60%-(2) 156.8 parts (mass solid content 80 parts) A crimped postcard paper for tri-fold ink jet recording was obtained in the same manner except that the amount was increased.

Comparative Example 10
[Production of tri-fold (double-sided coating) pressure-sensitive postcard paper for inkjet recording]
20% modified 51% natural rubber emulsion as pressure sensitive adhesive of Example 1 (1) 107.8 parts, 60% modified 51% natural rubber emulsion (2) 49.0 parts, 55% acrylic Emulsion-A 36.4 parts, except 55% acrylic emulsion-A, except 20% modified 51% natural rubber emulsion (2) 147.1 parts (mass solid content 75 parts) In this way, a crimped postcard paper for tri-fold ink jet recording was obtained.

Comparative Example 11
[Production of tri-fold (double-sided coating) pressure-sensitive postcard paper for inkjet recording]
A crimped postcard paper for tri-fold ink jet recording was obtained in the same manner as in Example 1 except that the 50% aqueous solution of dimethylamine / epichlorohydrin polycondensate having a quaternization ratio of 84% and a number average molecular weight of 2000 was removed.

Comparative Example 12
[Production of tri-fold (double-sided coating) pressure-sensitive postcard paper for inkjet recording]
The 50% aqueous dimethylamine / epichlorohydrin polycondensate having a quaternization ratio of 84% and a number average molecular weight of 2000 in Example 1 was converted to a 50% aqueous solution of dimethylamine / epichlorohydrin polycondensate having a quaternization ratio of 51% and a number average molecular weight of 1100. A crimped postcard paper for tri-fold inkjet recording was obtained in the same manner except that the same amount was replaced.

Comparative Example 13
[Production of tri-fold (double-sided coating) pressure-sensitive postcard paper for inkjet recording]
The 50% aqueous solution of dimethylamine / epichlorohydrin polycondensate having a quaternization ratio of 84% and a number average molecular weight of 2000 in Example 1 was converted to a 50% aqueous solution of dimethylamine / epichlorohydrin polycondensate having a quaternization ratio of 80% and a number average molecular weight of 1100. A crimped postcard paper for tri-fold inkjet recording was obtained in the same manner except that the same amount was replaced.

The trifold inkjet recording pressure-bonded postcard papers obtained in Examples 1 to 8 and Comparative Examples 1 to 13 were measured and evaluated by the following methods.
Measurement / Evaluation Method << Peel Strength >>
In the room at 23 ° C and 50% RH, the adhesive layer surface on which confidential information is printed should be the arrow (→) surface → N-shaped, folded in three so that it is 102mm wide x 152.5mm long. Set the pressure scale to the desired scale and perform crimping, then cut the crimped postcard paper into a size of 25 mm wide x 150 mm long, and the confidential information surface crimping part and the other address / standard item surface crimping part at a pulling speed of 300 mm A T-shaped peel test was conducted with a Tensilon universal tensile tester per minute, and the peel strength was measured. The pressure-sensitive postcard paper for tri-fold ink jet recording according to the present invention has a sealer pressure scale 30 in Example 1 that provides a confidential information surface peel strength of 0.65 N / 25 mm after 10 minutes of pressure bonding.
The unit is represented by N / 25 mm, and the larger the value, the stronger the peel strength.

<< Peel strength after UV irradiation >>
Using an ultraviolet curable ink printing vacuum baking machine equipped with a metal hydrolamp (1 kW) manufactured by I-Graphics Inc., the surface of the adhesive layer on which confidential information is printed with the speed dial setting 80 is irradiated with ultraviolet rays, and then the above << peeling strength >> The residual strength rate (%) was determined according to the following formula.

○: Peeling strength is 0.45 N / 25 mm or more, and the residual strength rate is 70% or more, which is excellent.
X mark: Peel strength is 0.30 N / 25 mm or less, and the residual strength rate is 50% or less, which is not practical.

<Peel strength after heating>
After heating in a circulating hot air dryer at 70 ° C. for 16 hours, the residual strength ratio (%) was determined by the following formula by measurement according to the above << Peel strength >>.

○: Peeling strength is 0.45 N / 25 mm or more, and the residual strength rate is 70% or more, which is excellent.
X mark: Peel strength is 0.30 N / 25 mm or less, and the residual strength rate is 50% or less, which is not practical.

《Paper tear after leaving in high humidity environment, tearing of base paper material》
Combine with the same method as the above sample for peel strength measurement, fold it in three, adjust the pressure scale of the dry sealer, and press it so that the peel strength after 1 day of press bonding is 1.00 N / 25 mm. After being allowed to stand in an environment of high temperature and high humidity of RH for 2 days, the measurement was performed according to the above << peel strength >>, and the peel strength of the confidential information surface, the paper tearing of the crimped portion, and the base paper material tear were evaluated.
○: Excellent with no paper tearing and tearing of the base paper.
Δ mark: Paper tearing and tearing of the base paper material are partially caused, which is not practical.
X mark: The paper is torn and the base paper material is completely broken, which is not practical.
Further, the peel strength measurement of Δ mark and X mark is impossible because it does not show normal strength due to partial or complete paper tearing and tearing of the base paper material.

<Inkjet print image density>
After injecting Versamark ink # 1069 black and # 2003 black into an ink cartridge of an ink jet printer (Canon: BJC420J), solid printing was performed on the adhesive layer surface on which confidential information was printed, and a Macbeth densitometer (RD918 type) one hour later. Then, the density of the printed part was measured. The larger the value, the higher the print density.

《Water resistance and sharpness of inkjet printed images》
After injecting Versamark ink # 1069 black, # 2001 cyan, # 2002 magenta, # 2003 black and # 2004 yellow into an ink cartridge of an ink jet printer (Canon: BJC420J), test printing is performed on the adhesive layer surface on which confidential information is printed. A pattern (characters, lines, solids) was printed, immersed in water for 20 minutes, and then the water resistance (decoloring degree) and image sharpness of the printed image after natural drying were visually determined.
◎: There is no color erasure and bleeding, and it is very excellent.
○ mark: Although fading slightly, it is excellent with no bleeding.
Δ mark, x mark: Discoloration and bleeding occur, which is not practical.

<Sticking of adhesive layer>
The stickiness of the adhesive layer surface on which confidential information is printed was evaluated by touch.
○: There is no stickiness and there is no practical problem.
X mark: There is stickiness, the stackability of the crimped postcard paper is inferior, and it is not practical.

  The above measurement / evaluation results are summarized in Table 1, Table 2, Table 3, and Table 4. Table 4 shows the overall evaluation. A: Excellent. ○ mark: Excellent. X mark: Not practical.

Claims (2)

  Mainly composed of pressure sensitive adhesive, fine particle filler, and ink fixing agent that can be peeled off under pressure without showing adhesiveness and adhesiveness under normal conditions on a base paper containing amphoteric polyacrylamide and polyamide / epichlorohydrin resin. A pressure-sensitive adhesive that is a pressure-sensitive adhesive in the presence of a nonionic surfactant to which 50 to 200 moles of ethylene oxide has been added is applied to the pressure-sensitive postcard paper for ink-jet recording provided with the adhesive layer composition. A modified natural rubber derivative obtained by graft polymerization of a monomer mainly composed of one or more selected from (meth) acrylic acid alkyl ester monomers with respect to 100 parts by mass of rubber in a range of 20 to 60 parts by mass, Two or more of these modified natural rubber derivatives having different graft polymerization rates are mixed, and a vinyl-based unsaturated compound in the form of carboxylic acid or acid anhydride is mixed. An acrylic acid alkyl ester having an alkyl group having 1 to 8 carbon atoms and an alkoxy acrylate having an alkoxy group having 1 to 4 carbon atoms in the presence of a dispersant comprising a polymer alkali neutralized salt having a monomer as an essential monomer component Ink fixing and pressure-sensitive adhesive containing acrylic emulsion having a glass transition temperature (Tg) of −50 to 0 ° C. obtained by emulsion polymerization of a monomer component containing 70% by mass or more of at least one ethyl ester A pressure-sensitive postcard paper for ink jet recording, characterized in that the agent is an alkylamine-epichlorohydrin polycondensate having a quaternization ratio of 84% or more by a colloid titration method.   2. The pressure-sensitive postcard paper for ink-jet recording according to claim 1, wherein the alkylamine / epichlorohydrin polycondensate has a number average molecular weight of 500 to 2,000.