JP6344822B2 - Inkjet recording pressure-sensitive paper - Google Patents

Description

  The present invention relates to a recording paper that performs pressure-sensitive adhesion. In particular, the present invention relates to a pressure-sensitive adhesive paper that performs printing by an inkjet method.

Crimp postcards that record personal information and confidential information are widely used from the viewpoint of confidentiality and transportation costs. The manufacturing method uses a paper with pressure sensitive adhesive that can be bonded by pressure as the base paper, records confidential information on it, folds it into two or three, and passes it between pressure rolls. Glue the faces and cut to postcard size. The person who received the postcard can read the recorded content by peeling off the adhered confidential surface, and after peeling, it cannot be reattached by the usual method. The confidentiality of As a similar feature, the pressure-sensitive paper is used for a plurality of uses such as a blind label and a delivery slip.

As a method for recording on the pressure-bonded paper, after fixed information which is a standard postcard is offset printed, variable information such as personal information, usage details, fee, barcode, two-dimensional barcode is printed. Conventionally, printing by a laser printer has been mainly used as a printing method for the variable information, but in recent years, ink jet printing capable of high-speed printing has been widely adopted.

Several pressure-sensitive papers recorded by such an ink jet method have been proposed. For example, Patent Document 1 discloses a pressure-bonded paper using 20 to 50% by mass of non-essential silica having an apparent specific gravity of 0.25 g / ml or more for an adhesive layer. Further, Patent Document 2 discloses a pressure-sensitive paper that defines the degree of steecht size of the base paper and uses a specific non-honed silica or polyvinyl alcohol as an adhesive component. Patent Document 3 discloses an adhesive layer. Is a pressure-sensitive adhesive paper using completely saponified polyvinyl alcohol, precipitated synthetic silica and gel synthetic silica in specific ratios. Patent Document 4 uses polyallylamine or polydiallyldimethylammonium chloride as the polymer component of the pressure-sensitive adhesive. Each of the pressure-sensitive papers is disclosed.

JP 2004-82466 A JP 2008-45115 A JP 2009-249745 A JP 2013-245273 A

Ink-jet pressure-bonded paper is required to have ink absorptivity and color density of ink in order to reliably fix ink for ink-jet recording onto the paper and display print information. In addition to this, when the pressure-sensitive paper is peeled off, it is required that the print is not transferred to the opposite surface (the surface that is in contact with the adhesive and separated after peeling).

  Accordingly, an object of the present invention is to provide a pressure-sensitive adhesive paper that has ink absorbability and ink coloring property of ink jet printing and does not cause print transfer after peeling.

Since silica is excellent in ink absorbability, it is generally used for inkjet recording applications. In particular, silica having high oil absorption is often used for ink jet recording paper as an ink acceptor. Similarly to this, silica having high oil absorption is used as an ink acceptor of the pressure-sensitive adhesive paper for ink jet recording. However, if the amount of silica in the pressure-sensitive adhesive is blended more than a certain amount in order to improve the ink color density, the strength of the pressure-sensitive adhesive layer is lowered and the surface strength of the pressure-bonded paper is lowered. Problems such as the printing surface partially falling off at the time of peeling and transferring to the opposite surface, or paper peeling at the time of printing occur. As described above, it has been difficult to combine all of the ink absorbability, the ink coloring property, and the surface strength of the pressure-bonded paper. The inventors have found that all the characteristics are obtained by setting the human sizing degree to a certain level or less, and have reached the present invention.

That is, the present invention is a pressure-sensitive adhesive paper having a pressure-sensitive adhesive layer composed of an adhesive base and silica on at least one side of the base paper,
The pressure-sensitive adhesive layer contains 30 parts by mass or more of silica having an oil absorption of less than 200 ml / 100 g with respect to 100 parts by mass of the adhesive base,
The present invention relates to a pressure-sensitive adhesive paper for ink-jet recording having a Steecht sizing degree of 50 seconds or less.

  It is preferable that the average particle diameter of the silica is 3 μm or less.

It is preferable that 40-60 mass parts of said silica is contained with respect to 100 mass parts of adhesive bases.

  The pressure sensitive adhesive layer preferably contains a vinylamidine copolymer.

  It is preferable that the vinylamidine copolymer is 1 to 50 parts by mass with respect to 100 parts by mass of the adhesive base.

When the pressure-sensitive paper of the present invention is employed, it is possible to achieve both ink absorptivity and color developability and the surface strength of the pressure-sensitive paper during printing by the ink jet method. Thereby, for example, high-speed inkjet printing is possible, and when the pressure-sensitive paper is peeled off, it is possible to avoid printing transfer to the opposite surface, so that it is possible to ensure information transmission as pressure-bonded paper.

The pressure-sensitive adhesive paper of the present invention has an adhesive layer made of an adhesive base and silica on at least one side of the base paper. This adhesive layer does not adhere under normal conditions, but has a function of adhering under specific pressure conditions and capable of being peeled off when necessary.

The adhesive base is composed of an adhesive main agent and an auxiliary adhesive. The adhesive main agent is not particularly limited as long as it exhibits the performance as a pressure-bonded paper. For example, natural rubber, synthetic rubber, other synthetic resins, etc. can be used, and it is called natural rubber latex or MG latex which is an aqueous polymer. One or a combination of two or more methyl methacrylate graft polymerized natural rubber latex and acrylic latex is used. These may be modified. In particular, natural rubber has a high adhesive force during pressurization, but is usually suitable for pressure bonding because of its low adhesiveness and tackiness.

The auxiliary adhesive has a function of adjusting the adhesive force and peelability as a pressure-sensitive adhesive layer. For example, SBR latex and its modified products, NBR latex, urethane emulsion, ethylene / vinyl acetate copolymer emulsion, polyvinyl alcohol Such modified products, various starches such as polyvinylpyrrolidone, carboxymethylcellulose, starch, modified starch, guar gum, gum arabic, gelatin, casein, styrene / maleic anhydride copolymer, urethane, polyacrylamide, dextrin, and the like can be used.

The mixing ratio of the adhesive main agent and the auxiliary adhesive must be adjusted appropriately because it affects the balance between the adhesive strength of the pressure-sensitive adhesive and the fixing properties to the base paper, the cohesive strength of the adhesive layer film, and the peelability. It is preferable that the adhesive main agent and the auxiliary adhesive have a mass ratio of 97: 3 to 50:50. When the auxiliary adhesive is less than 3 parts by mass, the fixing property of the pressure-sensitive adhesive to the base paper is lowered, and conversely, when the auxiliary adhesive exceeds 50 parts by mass, the adhesive layers adhere to each other on the overlapping surface. The force is reduced and proper peeling performance cannot be obtained.

In the present invention, silica having an oil absorption (ISO: 787-5) of less than 200 ml / 100 g is used. When silica having an oil absorption of 200 ml / 100 g or more is used, the ink absorbability is high, but the strength of the pressure-sensitive adhesive layer is lowered, so that the ink is transferred to the opposite surface when the pressure-sensitive paper is peeled off. On the other hand, if the amount of oil absorption is high, the viscosity of the paint at the time of preparing a paint provided with a pressure-sensitive adhesive layer increases and handling becomes worse. The oil absorption is preferably 180 ml / 100 g or less, more preferably 170 ml / 100 g or less, still more preferably 150 ml / 100 g. In addition, silica with low oil absorption is inferior in ink absorbency, but in order to compensate for this, it is necessary to achieve both ink absorbency and surface strength of the pressure-bonded paper by reducing the degree of stickiness of the pressure-bonded paper described later. Is possible.

Silica is blended in an amount of 30 parts by mass or more based on 100 parts by mass of the adhesive base. When the blending ratio is less than 30 parts by mass, the color density of the ink is lowered because there are few fine particles that accept ink. Preferably they are 30 to 80 mass parts with respect to 100 mass parts of adhesive bases, More preferably, they are 35 to 60 mass parts, More preferably, they are 40 to 60 mass parts is there. Exceeding 60 parts by mass is not preferable because the strength of the pressure-sensitive adhesive layer is lowered, and there is a risk that the layer may fall off or print transfer may occur when the pressure-sensitive paper is peeled. In addition, when the oil absorption amount of silica is 200 ml / 100 g or more, the strength of the pressure-sensitive adhesive layer is lowered as described above. However, since the present invention has an oil absorption amount of less than 200 ml / 100 g, 30 parts by mass or more of silica is blended. It becomes possible.

As the silica, synthetic silica such as precipitated synthetic silica and gel synthetic silica is preferably used, but the type is not particularly limited as long as it is less than 200 ml / 100 g. Precipitation synthetic silica, which is a sedimentation type, has a large primary particle and a relatively coarse aggregate structure. On the other hand, gel-type synthetic silica, which is a gel type, has a structure in which the primary particles are small and thus densely aggregated without any gaps. Thereby, the gel-like synthetic silica has a larger BET specific surface area, and the gel-like synthetic silica is superior also in the oil absorption of the silicone oil. Among gel-like synthetic silicas, those having a BET specific surface area of 200 m ² / g or more are particularly preferably used.

In this invention, it is preferable that the average particle diameter of a silica is 3 micrometers or less. If the average particle diameter exceeds 3 μm, characters and images may not be printed clearly. The average particle diameter here refers to the volume average particle diameter.

It is preferable to blend particles for preventing blocking in the pressure-sensitive adhesive layer. The particles preferably have an average particle diameter of 10 μm or more. Examples of the particles include silica, alumina, kaolin, titanium oxide, zeolite, zinc oxide, activated clay, glass powder, calcium carbonate, starch, and polyethylene. It is preferable that the compounding quantity of particle | grains is 40-70 mass parts per 100 mass parts of adhesive bases.

Furthermore, in the pressure-sensitive adhesive layer, a surfactant, a dispersant, a pH adjuster, an antifoaming agent, an adhesive, a release agent, a dye, a pigment, an antistatic agent, as long as the performance of the present invention is not impaired. Auxiliaries such as lubricants and antioxidants can be appropriately added.

  For example, the pressure sensitive adhesive layer preferably contains a vinylamidine copolymer. The vinylamidine copolymer contributes particularly to water resistance and fixing of magenta ink for ink jet printing, and has the effect of suppressing printing transfer to the opposing surface when the pressure-sensitive paper is peeled off.

  The vinylamidine copolymer is a polymer having a repeating unit of the following general formula (1) or a copolymer having a repeating unit of the following general formula (1) and other repeating units.

（式中、Ｒ_１及びＲ_２は、水素原子またはアルキル基を、Ａ⁻は陰イオンを表す。）
Ｒ_１及びＲ_２は、水素原子または炭素数１〜１０のアルキル基を表し、炭素数１〜１０のアルキル基は、より好ましくは炭素数１〜４のアルキル基であり、特に好ましくは炭素数１〜２のアルキル基である。Ａ⁻は陰イオンを表し、ＡＨで表される酸の対イオンである。ＡＨで表される酸としては、無機酸、有機酸のいずれでもよく、例えば、塩酸、硫酸、硝酸、リン酸、ピロリン酸、メタンスルホン酸、ｐ−トルエンスルホン酸等が挙げられ、特に塩酸、硫酸であることが好ましい。

(In the formula, R ₁ and R ₂ represent a hydrogen atom or an alkyl group, and A ⁻ represents an anion.)
R ₁ and R ₂ represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and the alkyl group having 1 to 10 carbon atoms is more preferably an alkyl group having 1 to 4 carbon atoms, particularly preferably a carbon number. 1 or 2 alkyl groups. A ⁻ represents an anion and is a counter ion of the acid represented by AH. The acid represented by AH may be either an inorganic acid or an organic acid, and examples thereof include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, pyrophosphoric acid, methanesulfonic acid, p-toluenesulfonic acid, etc., and particularly hydrochloric acid, Sulfuric acid is preferred.

Examples of other repeating units include a substituent-containing alkylene group having 2 to 7 carbon atoms, and specific examples include a cyanoalkylene group, a formaminoalkylene group, an acylaminoalkylene group, and an aminoalkylene group.

The reason why the vinylamidine copolymer is effective for fixing magenta ink is not clear, but it also has a diallyldimethylammonium chloride copolymer, a methyldiallylamine copolymer having the same five-membered heterocyclic structure, or also having an amidine group. Since the dicyandiamide copolymer has a small effect of suppressing the transfer of magenta ink, it is considered that having a five-membered heterocyclic structure having an amidine group is effective for water resistance of the magenta ink.

  The vinylamidine copolymer is preferably blended in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the adhesive base. If the amount is less than 1 part by mass, the fixing ability of the magenta ink to the pressure-bonding sheet is insufficient, and satisfactory print transfer suppression performance cannot be obtained. This is not preferable because sufficient adhesive strength as a sheet cannot be obtained.

The base paper of the present invention is preferably paper, but non-woven fabrics, woven fabrics, synthetic papers, synthetic films such as polyethylene, polyethylene terephthalate, polypropylene, and vinyl chloride, metal films, and the like can be used alone or in combination. When using a synthetic film or a metal film, it is preferable to subject the surface of the base paper to a surface treatment such as a mat treatment or a corona treatment.

Wood pulp that can be used is wood such as softwood bleached kraft pulp (NBKP), hardwood bleached kraft pulp (LBKP), softwood bleached sulfite pulp (NBSP), hardwood bleached sulfite pulp (LBSP), thermomechanical pulp (TMP), etc. Pulp is used alone or mixed. As the raw material wood, it is preferable to select a production area and tree species that do not contain a large amount of foreign matter. These wood pulps are mainly used, and if necessary, non-wood pulp such as hemp, bamboo, straw, kenaf, straw, three straws and cotton, modified pulp such as cationized pulp, mercerized pulp, rayon, vinylon, nylon, Synthetic fibers such as acrylic and polyester, chemical fibers, or microfibrillated pulp can be used alone or in combination.

In addition, in the range not impairing the performance of the present invention, for the papermaking fiber mainly composed of the above-described wood pulp, if necessary, an adhesive, an antifungal agent, various papermaking fillers, a wet paper strength enhancer, Add dry paper strength enhancer, sizing agent, colorant, fixing agent, yield improver, slime control agent, etc., then known and existing long net paper machine, circular net paper machine, short net paper machine, long net It can be obtained by making paper with various paper machines such as a circular net combination paper machine.

When the base paper is produced, if the beating of the wood pulp is advanced, the effect of increasing the paper interlayer strength can be expected. The beating degree is 200 to 650 ml c. s. f. It is preferable that

  The method for forming the pressure sensitive adhesive layer on the base paper is not particularly limited, but various coatings such as a bar coater, blade coater, die coater, roll coater, air knife coater, rod coater, curtain coater, gravure coater, comma coater, etc. You may coat using a construction apparatus and may provide by printing, such as an inkjet system and a gravure. The pressure sensitive adhesive layer may be provided on the entire surface of the base paper or may be provided partially. Further, it may be provided on one side or both sides of the base paper.

The amount of pressure sensitive adhesive layer provided to the base paper, is not particularly limited so delle performance as crimping paper, preferably 3 to 30 g / ^{m 2,} more preferably 5 to 20 g / ^{m 2,} 5 to 15 g / m ² is even more preferred.

  In addition, it is also possible to provide layers other than a pressure sensitive adhesive layer in the base paper in the range which does not impair the performance of this invention.

  The pressure-sensitive paper of the present invention may be subjected to processing such as calendering, super calendering, soft nip calendering, embossing, etc. during papermaking or after providing a pressure sensitive adhesive layer. Surface properties and thickness can be adjusted by processing.

  In the present invention, it is necessary that the pressure sizing degree of the pressure-bonded paper is 50 seconds or less. It is preferably 40 seconds or shorter, more preferably 30 seconds or shorter, and even more preferably 25 seconds or shorter. The ink absorbability increases as the sizing degree of the pressure-bonded paper is lower. If the Steecht sizing degree exceeds 50 seconds, the ink absorbability, fixability, and drying properties are deteriorated. In particular, when printing is performed with a high-speed rotary ink jet, the ink is required to be absorbed quickly, which is not suitable. Note that the degree of sizing of the present invention is measured from the pressure-sensitive adhesive layer side.

  In order to design the sticky sizing degree of the pressure-bonded paper within the above range, the sizing degree of the base paper and the layer provided on the base paper may be appropriately adjusted. For example, the amount of sizing agent or water repellent applied to the base paper or the pressure sensitive adhesive layer may be adjusted, or a layer different from the pressure sensitive adhesive layer may be provided.

The pressure-sensitive paper of the present invention preferably has a basis weight of 80 to 150 g / m ² .

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely using an Example and a comparative example, the scope of the present invention is not limited to an Example.

(1) Stichtite sizing degree The squeecht sizing degree of the surface of the pressure-sensitive adhesive paper on the pressure-sensitive adhesive layer side was measured in accordance with JIS P8122.

(2) Evaluation of inkjet printing Test printing using an aqueous ink (trade names “BCI-321 + 320 / 5MP”, “BCI-321GY”, manufactured by Canon) for an inkjet printer (trade name “MP990”, manufactured by Canon) A pattern was printed on a pressure-sensitive adhesive paper, and ink absorbency and color development were evaluated.
(2-1) Ink absorbency: The absorbency immediately after printing was visually evaluated.
◎: Solid print part is completely absorbed even immediately after printing ○: Solid print part is completely absorbed within 5 seconds after printing x: It takes 6 seconds or more after printing for the solid print part to completely absorb (2-2 ) Color development: The color density (OD value) after printing was evaluated with a densitometer (trade name “MACBETH CH-8105”, manufactured by Gretag Macbeth).
A: O. of black solid printing part. D. Is 1.1 or more. O: O. of black solid print portion. D. Is 1.0 or more
X: O. of black solid print part D. Is less than 1.0

(3) Evaluation of ink transfer The pressure-bonded paper after printing in (2) above was cut into a width of 25 mm and a length of 100 mm to prepare a sample, and the two samples were stacked with a length of 25 mm and 7 MPa. The above load was applied and crimped. In accordance with JIS-K6854, the adhesive peel strength test method was used to perform a T-type peel test using a universal testing machine (trade name “Tensilon”, manufactured by Orientec Co., Ltd.) to transfer the ink on the peeled surface. The presence or absence of was visually observed and evaluated as follows.
◎: Almost no transfer ○: Transfer can be seen, but characters and barcodes cannot be read ×: Transferred characters and barcodes can be read clearly

[Manufacture of base paper]
20 parts by weight of softwood bleached kraft pulp and 80 parts by weight of hardwood bleached kraft pulp were 430 ml C.I. S. F. And adding 0.9 parts by mass of rosin sizing agent (trade name “Size Pine E”, manufactured by Arakawa Chemical Industries, Ltd.) and 3.5 parts by mass of sulfuric acid band to prepare a stock, A paper having a basis weight of 85 g / m ² was made using a machine to obtain a base paper.

[Example 1]
As an adhesive base, 30 parts by mass of silica having an average particle diameter of 1.2 μm and an oil absorption of 133 ml / 100 g, and an average particle diameter of 20 μm with respect to 100 parts by mass of natural rubber latex obtained by grafting methyl methacrylate to natural rubber. 60 parts by mass of starch was prepared. This was coated on both sides of the base paper by 7 g / m ² using an air knife coater to obtain a pressure-bonded paper. The Steecht sizing degree was 48 seconds.

[Example 2]
As an adhesive base, 70 parts by mass of silica having an average particle diameter of 1.2 μm and an oil absorption of 133 ml / 100 g, and an average particle diameter of 20 μm, based on 100 parts by mass of natural rubber latex obtained by graft polymerization of methyl methacrylate on natural rubber. 60 parts by mass of starch was prepared. This was coated on both sides of the base paper by 7 g / m ² using an air knife coater to obtain a pressure-bonded paper.

[ Reference example ]
A pressure-bonded paper was obtained in the same manner as in Example 1 except that silica having an average particle diameter of 7 μm and an oil absorption of 190 ml / 100 g was used.

[Example 3 ]
As an adhesive base, 2 parts by mass of vinylamidine copolymer (trade name “KP7000”, manufactured by Daianitrix) per 100 parts by mass of natural rubber-based latex obtained by graft polymerization of methyl methacrylate to natural rubber, average 70 parts by mass of silica having a particle diameter of 1.2 μm and an oil absorption of 133 ml / 100 g and 60 parts by mass of starch having an average particle diameter of 20 μm were prepared. This was coated on both sides of the base paper by 7 g / m ² using an air knife coater to obtain a pressure-bonded paper.

[Comparative Example 1]
A pressure-bonded paper was obtained in the same manner as in Example 1 except that silica having an average particle size of 2.3 μm and an oil absorption of 255 ml / 100 g was used.

[Comparative Example 2]
A pressure-bonded paper was obtained in the same manner as in Example 1 except that the silica was changed to 25 parts by mass with respect to 100 parts by mass of the natural rubber latex.

[Comparative Example 3]
A pressure-bonded paper was obtained in the same manner as in Example 1 except that the rosin sizing agent of the base paper was changed to 1.8 parts by mass. The Steecht sizing degree was 70 seconds.

As a result of evaluating the pressure-sensitive adhesive paper obtained in Examples and Comparative Examples, the pressure-sensitive papers of Examples 1 to 3 did not have any problems in all evaluations. In the reference example, slight transfer was slightly confirmed. In Example 3 , there was no transfer of magenta ink in particular. On the other hand, with the pressure-sensitive adhesive paper of Comparative Example 1, print transfer was observed in the peel evaluation after pressure bonding. In Comparative Example 2, the color density of the inkjet ink was low, and the pressure-sensitive paper of Comparative Example 3 had poor ink absorbability.

  From the above results, it was confirmed that the pressure-sensitive adhesive paper for ink-jet recording of the present invention can obtain the absorbability and color developability of the ink-jet ink and can have a surface strength without print transfer after peeling. It was.

Claims (5)

A pressure-sensitive adhesive paper having a pressure-sensitive adhesive layer composed of an adhesive base (excluding starch) and silica on at least one side of a base paper,
The silica has an average particle size of 3 μm or less,
The pressure-sensitive adhesive layer contains 30 parts by weight or more and 80 parts by weight or less of silica having an oil absorption of less than 200 ml / 100 g with respect to 100 parts by weight of the adhesive base.
A pressure-sensitive adhesive paper for ink jet recording, having a Steecht sizing degree of 50 seconds or less. Furthermore, the pressure-sensitive adhesive layer for inkjet recording according to claim 1, wherein the pressure-sensitive adhesive layer contains particles having an average particle diameter of 10 µm or more. The pressure-sensitive adhesive paper for inkjet recording according to claim 1 or 2 , wherein the silica is contained in an amount of 40 to 60 parts by mass with respect to 100 parts by mass of the adhesive base. The pressure-sensitive adhesive paper for ink jet recording according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive layer contains a vinylamidine copolymer. The pressure-sensitive adhesive paper for inkjet recording according to claim 4 , wherein the compounding amount of the vinylamidine copolymer is 1 to 50 parts by mass with respect to 100 parts by mass of the adhesive base.