JP2001262104A - Pressure-sensitive adhesive composition excellent in fixability of inkjet ink and sheet for carrying information using the same - Google Patents

Abstract

(57) [Summary] PROBLEM TO BE SOLVED: There is no problem such as elution of a cationic resin during wet offset printing to cause staining of a printing plate, and is excellent in printability, and excellent in water resistance of a printed inkjet ink and Provided is a pressure-sensitive adhesive composition which does not cause ink offset and has excellent ink fixability. And an information carrying sheet having an adhesive layer of the pressure-sensitive adhesive composition. The styrene-methyl methacrylate graft copolymer natural rubber-based adhesive base has an average particle diameter of 1 to 1.
A pressure-sensitive adhesive composition in which alumina fine particles of 100 nm are blended and the pH of the entire pressure-sensitive adhesive composition is adjusted to a range of 4 to 9.5 is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive composition excellent in fixability of an ink-jet ink and an information carrying sheet using the same, and more particularly, to a surface laminated by folding or cutting. Information transmission sheet such as a foldable sheet, which is used as an information carrying surface, a confidential information transmission sheet such as a superimposed sheet, an arrangable sheet which can be expanded in size, an office sheet such as copy paper, and the like. The present invention relates to a pressure-sensitive adhesive composition having excellent fixability of an inkjet ink.

[0002]

2. Description of the Related Art Conventionally, in an information carrying sheet that carries information on a superposed surface, a base sheet is usually formed in a pattern such that the superposed surfaces are in contact with each other so that the superposed surfaces are bonded to each other. An adhesive layer of a pressure-sensitive adhesive is provided on the entire surface, a specific portion, or a line of the overlapping surface. This pressure-sensitive adhesive is also called self-adhesive pressure-sensitive adhesive,
By applying a high pressure while the adhesive layers are in contact with each other, the mutual polymers adhere to each other by self-diffusion. Depending on the type of the composition and the degree of pressure, permanent adhesion or re-peeling is performed. It embodies the adhesiveness.

In recent years, an ink jet recording system has been rapidly spread as a method for variably printing addresses, names, individual information, and the like. In particular, color printing (process printing), which is comparable to the conventional plate making technology, has become possible due to the spread of ink colorization. Ink for inkjet printers has the drawback that when printed in water such as rain, it dissolves and becomes invisible when printed in water such as rainwater. It is required to increase.
Method of blending cationic resin with pressure-sensitive adhesive
No. 71758, JP-A-9-119094, etc.) and a method of interposing a cationic resin between a base sheet and a pressure-sensitive adhesive (JP-A-9-104167, etc.) have been proposed. However, there are problems that the effect is insufficient, and that the cationic resin elutes during wet offset printing to cause printing plate staining.

A conventional pressure-sensitive adhesive is prepared by printing ink on an adhesive layer using an ink jet printer, and then bonding the adhesive layer printed with ink jet ink to the adhesive layer not printed with ink jet ink. When the information carrying sheet adhered by applying a strong pressure is removed again, there is a problem that the printed inkjet ink moves to the adhesive layer side where the inkjet ink is not printed (ink offset).

A first object of the present invention is to solve the conventional problems and improve the water resistance of a printed ink-jet ink.
A second object of the present invention is to provide a pressure-sensitive adhesive composition having excellent fixability of a removable ink-jet ink which prevents ink offset from occurring.
An object of the present invention is to provide an information carrying sheet using a pressure-sensitive adhesive composition excellent in fixability of such an inkjet ink.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, blended alumina fine particles having a specific average particle diameter with a specific natural rubber adhesive base. By adjusting the pH of the entire adhesive composition to a specific range, styrene-methyl methacrylate graft copolymerized natural rubber-based adhesive base is prevented from agglomerating, and the pressure-sensitive ink jet ink has excellent fixability. They have found that an adhesive composition can be provided, and have completed the present invention.

That is, the pressure-sensitive adhesive composition according to the first aspect of the present invention, which has excellent fixability of an ink-jet ink,
An adhesive layer that is applied to the overlapping surface of the sheet and does not adhere in a normal state by a drying process is formed, and the overlapping surfaces are brought into contact with each other and given a predetermined pressure, so that the overlapping surfaces can be peeled off. A pressure-sensitive adhesive composition to be adhered, wherein the styrene-methyl methacrylate graft copolymer natural rubber-based adhesive base has an average particle diameter of 1 to 1.
It is characterized in that alumina fine particles of 100 nm are blended and the pH of the whole pressure-sensitive adhesive composition is adjusted to a range of 4 to 9.5.

According to a second aspect of the present invention, there is provided an information carrying sheet comprising an adhesive layer of the pressure-sensitive adhesive composition excellent in fixability of an ink jet ink according to the first aspect, on a predetermined portion of a superposed surface of a base sheet. It is characterized by having.

In the pressure-sensitive adhesive composition of the present invention, alumina fine particles that are insoluble in water are used, and no cationic resin is used. This eliminates problems such as elution of the cationic resin during wet offset printing to cause printing plate contamination. By using the pressure-sensitive adhesive composition of the present invention, the water resistance of the printed inkjet ink is improved, and ink offset does not occur.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As the natural rubber-based adhesive base used in the pressure-sensitive adhesive composition of the present invention, a latex containing natural rubber as a main component, a modified product thereof, for example, an acidic latex, a depolymerization Of latex, vulcanized latex or grafted natural rubber latex, especially in terms of water resistance, blocking resistance, heat resistance, abrasion resistance, etc., especially natural rubber is graft copolymerized with methyl methacrylate and styrene. The obtained natural rubber latex is preferably used.

The natural rubber latex obtained by graft copolymerizing methyl methacrylate and styrene onto natural rubber, which is preferably used in the pressure-sensitive adhesive composition of the present invention, is obtained by adding, for example, methyl methacrylate to 100 parts by mass of natural rubber. About 40 parts by mass About 1 to 10 parts by mass of styrene is graft copolymerized.

In the pressure-sensitive adhesive composition of the present invention, it is necessary to mix fine alumina particles having an average particle diameter of 1 to 100 nm with a natural rubber-based adhesive base without using a cationic resin. If the average particle diameter of the alumina fine particles is less than 1 nm or more than 100 nm, water resistance and ink offset may not be improved. Average particle size 1-100
It is considered that the use of a predetermined amount of the alumina fine particles having a thickness of nm improves the ink-jet ink's adsorptivity and improves water resistance and ink offset. Since alumina fine particles that are not soluble in water are used, problems such as elution of the cationic resin during wet offset printing and contamination of the printing plate are eliminated.

In the present invention, in addition to the alumina fine particles,
Other fine particle fillers can be blended with the natural rubber-based adhesive base. It is preferable to use a water-resistant fine particle filler having a regular particle shape.

Examples of other fine particle fillers include various types of starch-based fine particles, fine spherical acrylic resin, fine spherical methacrylic resin, fine spherical polyethylene, glass powder, shirasu balloon, natural zeolite, synthetic zeolite, calcium carbonate, activated clay, and the like. No. These fine particle fillers may be used alone or in combination of two or more.

The natural rubber-based adhesive base used in the light-sensitive pressure-sensitive adhesive composition of the present invention may include, if desired, additives commonly used in adhesives, such as tackifiers, viscosity modifiers, and the like.
Anti-aging agents, stabilizers, coloring agents and the like can be added.

When an alumina fine particle having an average particle diameter of 1 to 100 nm is blended with 100 parts by mass of a styrene-methyl methacrylate graft copolymer natural rubber adhesive base (solid content), an anionic natural rubber adhesive is obtained. Aggregation occurs due to the action of the base and the cationic alumina fine particles, but the pH of the entire pressure-sensitive adhesive composition is adjusted within the above-mentioned predetermined range by adding an acidic aqueous solution such as an acetic acid aqueous solution or a hydrochloric acid aqueous solution. Thereby, aggregation is avoided and a uniform pressure-sensitive adhesive composition is obtained. If the pH exceeds 9.5, styrene
Aggregation of the methyl methacrylate copolymer natural rubber adhesive base occurs, and if the pH is less than 4, there is a possibility that the base sheet, machine, skin, and the like will be adversely affected.

The pressure-sensitive adhesive composition of the present invention is applied to the surface of a base sheet by a coating means such as a gravure coater, flexo, air knife coater, bar coater, etc., and is folded in two, three, folded or separated. It can be suitably used for postcards, spreadsheets, notices, various cards, etc., which have a double-sided surface that is temporarily adhered in various forms such as superposition, but can be easily peeled off as needed.

Next, as the substrate sheet on which the adhesive composition of the present invention is applied, in addition to ordinary paper, synthetic paper or a synthetic film of polyethylene, polyethylene terephthalate, polypropylene, vinyl chloride or the like may be used. it can. When using these synthetic films, the surface of the base sheet is preferably subjected to a surface treatment such as a mat treatment or a corona treatment. The amount of the adhesive composition applied to the substrate sheet surface is 1 to 30 g / m ² , preferably 3 to maintain the adhesiveness, peelability or transparency of the adhesive layer.
-20 g / m ² , more preferably 5-15 g / m ² . Furthermore, by pressing the formed peelable adhesive layer with a pressure roller at about 1 to 10 kg / cm ² , the blocking resistance can be further improved.

Examples of the ink for ink jet recording that can be used in the present invention include, for example, JP-A-7-2
Nos. 28808 and 7-228809 can be used. In particular, anthraquinones,
Benzoquinone, naphthoxyquinone, xanthene,
Triphenylmethane, quinoline, indigoid,
At least one anionic ink selected from the group consisting of azine, oxazine, thiazine and methine dyes is preferably used. These specific examples are illustrated in paragraph No. 0015 of JP-A-7-228809. As a medium used for this ink, a mixed solvent of water and a water-soluble organic solvent can be used.
In addition, a pH adjuster, a viscosity adjuster, a surface tension adjuster and the like can be contained.

Next, the configuration of the information carrying sheet of the present invention will be described in detail with reference to the accompanying drawings. Here, FIG.
FIG. 2 is a front view of the three-fold postcard of the present invention, FIG. 2 is a rear view of the postcard, FIG. 3 is a cross-sectional view taken along line XX of FIG.
FIG. 5 is an explanatory view of the state when the postcard of FIG. 1 is folded, FIG. 5 is a front view of the folded postcard of the present invention, FIG. 6 is a developed view of the back side of the postcard, and FIG. 8 and FIG. 8 are front development views of the partially folded postcard according to the present invention, FIG. 9 is a rear development view of the postcard, and FIG. 10 is a state explanatory view when the postcard of FIG. 8 is folded.

First, a three-fold postcard 1 shown in FIGS. 1 to 3 is composed of a base sheet 2 having a size three times the size of a standard postcard, and is divided into three regions by folding lines 3a and 3b. is there. On the front surface of the left section area A, print destination information such as a zip code, a destination name, and an address.
However, concealment information prints 5 are printed directly on the base sheet 2 on the front and back surfaces of the central partitioned area B and on the front face of the right partitioned area C. Further, the pressure-sensitive adhesive composition of the present invention is applied to the entire front surfaces of the divided regions B and C and the whole back surfaces of the divided regions A and B of the printed base sheet 2 by the adhesive layer 6 which can be peeled off. Is formed. As shown in FIG. 4, the tri-fold postcard 1 configured as described above folds the overlapping surface of each section into a Z-shape along the folding lines 3a and 3b to bring the adhesive layers into contact with each other. By pressing with a sealer, the adhesive layer 6 is activated and adhered.

Next, a two-fold postcard 11 shown in FIGS. 5 and 6 is composed of a base sheet 2 having a size twice as large as a standard postcard, and is divided into two regions D and E by a fold line 3 at the center. It is what is divided. A destination information print 4 such as a postal code, a destination name and an address is printed on the front surface of the left section area D, and a concealment information print 5 is printed directly on the base sheet 2 on the back sides of the section areas D and E. . further,
The pressure-sensitive adhesive composition of the present invention is applied to the entire back surface of the divided areas D and E of the printed base sheet 2 to form a peelable adhesive layer 6. As shown in FIG. 7, the two-fold postcard 11 configured as described above is folded and pressed at the fold line 3 so that the adhesive layers on the right and left rear surfaces are in contact with each other, similarly to the above-described three-fold postcard. The adhesive layer 6 is activated and adhered.

8 and 9 is composed of a base sheet 2 having a size 1.5 times the size of a standard postcard. And G. The postal code, address,
A destination information print 4 such as an address, and a concealment information print 5 is printed directly on the base sheet 2 on the back surface of the right side divided area G. Further, the pressure-sensitive adhesive composition of the present invention is applied to the entire back surface of the partitioned area G of the printed base sheet 2 and a part of the back face of the partitioned area F which is overlapped when the partitioned area G is folded along the folding line 3. Adhesive layer 6 to which object is applied and which can be peeled off
Are formed. As shown in FIG. 10, the partially folded postcard 21 configured as described above is folded and pressed at the folding line 3 so that the adhesive layers on the back surfaces of the left and right sections are in contact with each other, similarly to the above-described two-fold postcard. Thereby, the adhesive layer 6 is activated and adhered.

Further, the peelable adhesive layer formed by the composition of the present invention itself also has a receptivity for printing ink and toner. Therefore, if necessary, a normal printing device or a non-impact printer may be further provided on the surface thereof. Can print additional information (not shown).

[0025]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. (Example 1) As a natural rubber-based adhesive base, natural rubber 1
Based on 100 parts by mass of styrene-MMA copolymerized natural rubber emulsion obtained by mixing 2 parts by mass of styrene and 10 parts by mass of methyl methacrylate (MMA) with 100 parts by mass and graft-copolymerizing the mixture. A mixture of 5 parts by mass of a terpene resin was used as a thickener. To 100 parts by mass (solid content) of the natural rubber-based adhesive base, 60 parts by mass of wheat starch having an average particle size of 15 μm was added, and the mixture was stirred well. Subsequently, 40 parts by mass (as a solid content) of alumina fine particles (AL203C manufactured by Nippon Aerosil Co., Ltd., containing 15% by weight of alumina fine particles) dispersed in water and a 5% aqueous acetic acid solution were added in appropriate amounts to adjust the pH of the entire composition to 9. A pressure-sensitive adhesive composition of the present invention, No. 15, was prepared.

The pressure-sensitive adhesive composition of the present invention was used in an amount of 70
5 kg of high quality paper (base sheet) with an air knife coater
g / m ² to form an adhesive layer.
Heating was performed at 20 ° C. for 30 seconds to perform a drying treatment. After printing (black, red, blue, and green inks) on the adhesive layer of the information carrying sheet thus produced by a Cytex inkjet printer, water resistance and ink offset were evaluated by the following methods. It is shown in Table 1.

(1) Water resistance: The printed portion is washed away with running water for a certain period of time, or a water droplet is dropped on the printed portion for a certain period of time, and then wiped off to visually determine the state of the ink. If the print is completely left ◎, if the print almost completely remains ○, if the print is a little thin, △,
Those with light prints were judged as x.

(2) Ink offset: After folding in two with the printing surface inside and pressing and integrating, it was peeled off again, and it was visually determined whether or not the ink was offset to the opposite surface. ◎ indicates that the offset phenomenon has not occurred at all and the shape of the print remains exactly, も の indicates that the offset phenomenon has hardly occurred, ○, the print is slightly transferred to the adhesive composition surface opposite to the printed surface, A sample in which the offset phenomenon occurred slightly was evaluated as Δ, and a sample in which the print was transferred to the surface of the adhesive composition opposite to the surface on which the image was printed, and in which the offset phenomenon clearly occurred was evaluated as ×.

(Example 2) Water resistance was measured in the same manner as in Example 1 except that 30 parts by mass of wheat starch and 60 parts by mass of alumina fine particles were blended to prepare a pressure-sensitive adhesive composition of the present invention.
Table 1 shows the results of evaluating the ink offset.

Example 3 Water resistance and ink were prepared in the same manner as in Example 1 except that 120 parts by mass of wheat starch and 30 parts by mass of alumina fine particles were blended to prepare a pressure-sensitive adhesive composition of the present invention. Table 1 shows the results of evaluating the offset.

Comparative Example 1 Water resistance and ink offset were prepared in the same manner as in Example 1 except that a comparative pressure-sensitive adhesive composition was prepared using alumina fine particles as silica fine particles (Mizukasil P-526, manufactured by Mizusawa Chemical Co., Ltd.). Are shown in Table 1.

Example 4 As a natural rubber adhesive base, styrene-MMA copolymer natural rubber emulsion (FB-DO-3, manufactured by Mitsui & Co., Solvent Coating Co., Ltd.)
20 parts by mass of wheat starch having an average particle size of 15 μm was added to 100 parts by mass (solid content), and the mixture was stirred well. Subsequently, alumina fine particles separately dispersed in water (AL made by Nippon Aerosil Co., Ltd.)
A pressure-sensitive adhesive composition of the present invention having a pH of 9.10 is prepared by adding an appropriate amount of 40 parts by mass (as solid content) of 203C, 15% by mass of alumina fine particles) and a 5% aqueous solution of acetic acid. did.

The pressure-sensitive adhesive composition of the present invention was used in an amount of 10
5 kg of high quality paper (base sheet) is coated with an air knife coater at a rate of 5 g / m ² to form an adhesive layer.
Heating was performed at 120 ° C. for 30 seconds to perform a drying treatment. After printing (black, red, blue, and green inks) on the adhesive layer of the information carrying sheet thus produced by a Cytex inkjet printer, water resistance and ink offset were evaluated in the same manner as in Example 1. Table 1 shows the evaluation results.

(Example 5) The results of evaluating water resistance and ink offset in the same manner as in Example 4 except that 10 parts by mass of wheat starch was blended to prepare the pressure-sensitive adhesive composition of the present invention are shown in Table 1. It is shown in FIG.

Example 6 Water resistance was measured in the same manner as in Example 1 except that 60 parts by mass of wheat starch and 60 parts by mass of alumina fine particles were blended to prepare a pressure-sensitive adhesive composition of the present invention.
Table 1 shows the results of evaluating the ink offset.

Example 7 20 parts by mass of alumina fine particles and silica fine particles (Mizukasil manufactured by Mizusawa Chemical Co., Ltd.)
Table 1 shows the results of evaluating water resistance and ink offset in the same manner as in Example 4 except that the pressure-sensitive adhesive composition of the present invention was prepared by blending 20 parts by mass of P-526).

Comparative Example 2 Water resistance and ink offset were prepared in the same manner as in Example 4 except that a comparative pressure-sensitive adhesive composition was prepared using alumina fine particles as silica fine particles (Mizukasil P-526, manufactured by Mizusawa Chemical Co., Ltd.). Are shown in Table 1.

Comparative Example 3 Water resistance and ink offset were performed in the same manner as in Example 1 except that a comparative pressure-sensitive adhesive composition was prepared using alumina fine particles as silica fine particles (Mizukasil P-78A, manufactured by Mizusawa Chemical Co., Ltd.). Are shown in Table 1.

[0039]

[Table 1]

From Table 1, it can be seen that the pressure-sensitive adhesive compositions of the present invention of Examples 1 to 7 are excellent in printability and water resistance.
It is clear that the ink offset is excellent and the offset phenomenon does not occur. On the other hand, it can be seen that the pressure-sensitive adhesive compositions for comparison of Comparative Examples 1 to 3 are inferior in water resistance and may cause an offset phenomenon.

[0041]

The pressure-sensitive adhesive composition according to the first aspect of the present invention does not use a cationic resin, so that there is no problem that the cationic resin is eluted during wet offset printing to cause a printing plate stain, and the printing suitability is improved. In addition to being excellent in water resistance, the printed ink-jet ink is excellent in water resistance, so there is no bleeding of the print due to rain or sweat from the hand, and ink offset does not occur, and the ink-jet ink has excellent fixability. Has a remarkable effect.

The information carrying sheet according to the second aspect of the present invention can be obtained economically and advantageously at a low production cost, is recordable by an ink jet recording method, and is concealed by peeling off its interface. In addition, there is no risk of blocking due to stacking during storage of the sheet, etc., the printed ink-jet ink has excellent water resistance, and the surface of the pressure-sensitive adhesive composition when the interface is peeled off. The offset phenomenon in which the information recorded on the recording medium is transferred to the opposite bonding surface does not occur.

[Brief description of the drawings]

FIG. 1 is a surface development view of a three-fold postcard according to the present invention.

FIG. 2 is a developed rear view of the postcard of FIG. 1;

FIG. 3 is a sectional view taken along line XX of FIG. 1;

FIG. 4 is an explanatory view of the state when the postcard of FIG. 1 is folded.

FIG. 5 is a surface development view of the two-fold postcard of the present invention.

FIG. 6 is a developed rear view of the postcard of FIG. 5;

FIG. 7 is an explanatory diagram of a state when the postcard of FIG. 5 is folded.

FIG. 8 is a surface development view of a partially folded postcard according to the present invention.

FIG. 9 is a developed rear view of the postcard of FIG. 8;

FIG. 10 is an explanatory view of the state when the postcard of FIG. 8 is folded.

[Explanation of symbols]

 2, 12, 22 Base sheet 3, 3a, 3b Folding line 5 Concealment information printing 6 Peelable adhesive layer

Claims (2)

[Claims] An adhesive layer which is applied to a superposed surface of a sheet and which does not adhere in a normal state by a drying process is formed, and the superposed surfaces are brought into contact with each other and a predetermined pressure is applied thereto, whereby the superposed surface is formed. A pressure-sensitive adhesive composition for releasably adhering each other, with respect to a styrene-methyl methacrylate graft copolymer natural rubber-based adhesive base,
Alumina fine particles with an average particle diameter of 1 to 100 nm are blended,
A pressure-sensitive adhesive composition excellent in fixability of an inkjet ink, wherein the pH of the entire pressure-sensitive adhesive composition is adjusted to a range of 4 to 9.5. 2. An information carrying sheet having an adhesive layer of the pressure-sensitive adhesive composition according to claim 1 on a predetermined portion of a superposed surface of a base sheet.