JP2003155461A - Delayed tack pressure-sensitive adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a delayed tack pressure-sensitive adhesive sheet for inkjet recording which has an uneven printed surface with durability and water resistance. SOLUTION: This delayed tack pressure-sensitive adhesive sheet for inkjet recording has a cushioning layer and an ink reception layer containing an inorganic pigment, the layers being formed on at least one side of a substrate. The ink reception layer further contains a solid plasticizer, a pressure-sensitive adhesive, and a tackifier. The cushioning layer is preferably a resin having a 100% modulus (according to JIS K6301) of 100 kg/cm<2> or lower. The mixing ratio by pts.mass of the inorganic pigment to the pressure-sensitive adhesive is preferably (10/100)-(100/100).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a delayed tack type pressure-sensitive adhesive sheet in which the surface of a substrate of paper or film is provided with both ink jet recording suitability and delayed tack property. The delayed tack type pressure-sensitive adhesive sheet of the present invention exhibits tackiness after being printed on the tack surface for a short period of time by being exposed to a heat source such as a heater or a hot air burner, and then tacked on cans, bottles, boxes, etc. which are packaging materials for products. It can be attached as a label. In particular, the present invention relates to a delayed tack type pressure-sensitive adhesive sheet which has no distortion of characters and images attached even when the surface of cans, bottles, boxes, etc. has irregularities. Further, the present invention relates to an adhesive sheet which has an advantage that unnecessary dust is not generated because a release paper is not required.

[0002]

2. Description of the Related Art Conventionally, paper coated with an ink receiving layer,
When characters, symbols, patterns, etc. are printed on a base material such as a film and then attached to an article, the back surface of the base material is permanently tacked and a release paper is temporarily attached, or a delayed tack type adhesive material. A delayed tack type adhesive sheet coated with is used. The delayed tack type pressure-sensitive adhesive sheet has a feature that it is non-tacky at room temperature, but develops tackiness by heating, and maintains tackiness for a while even if it is not heated thereafter.

A pressure-sensitive adhesive label obtained by imparting inkjet suitability to a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive property at room temperature is disclosed in JP-A-8-30.
It is reported in Japanese Patent Publication No. 198. However, with this configuration, when printing with an inkjet printer, handling becomes complicated because the printing surface has adhesiveness. Further, it is necessary to temporarily attach release paper when the above-mentioned sheet is stored, which is inferior in workability and productivity when it is automatically applied as a label to an article, a product, etc. on a factory site line, and a release paper is required. As a result, the cost increases, and problems such as discarding the release paper after use occur.

As a delayed tack type pressure-sensitive adhesive sheet for ink jet recording, a sheet having a delayed tack layer provided on one surface of a substrate and having an ink jet aptitude on the opposite surface is reported in Japanese Utility Model Publication No. 6-50221.
However, the printed surface is always exposed to the surface, which causes problems in durability and water resistance. After printing on such a sheet, it is possible to adhere another transparent film to protect the printed surface, but this is not preferable because the work process becomes complicated.

Japanese Unexamined Patent Publication No. 9-305117 proposes a delayed tack type pressure-sensitive adhesive sheet in which an ink receiving layer and a delayed tack layer are laminated on a substrate.
When the surface of bottles, boxes, etc. has irregularities, there is a problem that the characters and images attached along the irregularities of the surface are distorted.

[0006] In addition, in cards such as IC cards that have become widespread in recent years, in which IC chips are inserted between a plurality of layers, the flatness is deteriorated due to the curving of the card, and dust generated by cutting is inter-layered. Is likely to be deteriorated in flatness due to being mixed in with or adhering to the base material, or due to insertion of an IC chip between layers,
There is a problem that the distortion of characters occurs along the unevenness of the card surface.

Further, since cards are generally used repeatedly, there is a problem in image storability such as water resistance and scratch resistance of an image simply by sticking an ink jet recording material on the card. , Its improvement was also required.
Particularly for cards such as IC cards, strong image storability is required because they are expected to be used repeatedly many times.

[0008]

SUMMARY OF THE INVENTION According to the present invention, the quality of the printing surface can be maintained for a long period of time by protecting the printing surface from the outside air and moisture without complicating the working process. Provided is a delayed tack type pressure-sensitive adhesive sheet which is non-adhesive at room temperature but has an inkjet suitability that develops adhesiveness when heated. In particular, it provides a delayed tack type pressure-sensitive adhesive sheet having no distortion in characters or images even on the surface having irregularities.

[0009]

An object of the present invention is to provide a cushion layer and an ink receiving layer containing an inorganic pigment on at least one surface of a substrate by laminating, and further a solid plasticizer and an adhesive agent in the ink receiving layer. It was solved by containing an agent and a tackifier.

The cushion layer of the present invention is JIS K63.
100% modulus specified in 01 is 100 Kg / c
It is preferable to use a resin having m ² or less as a main component.

The mixing ratio of the inorganic pigment and the pressure-sensitive adhesive contained in the ink receiving layer is such that the pigment is 1 part by weight relative to 100 parts by mass of the pressure-sensitive adhesive.
It is preferably in the range of 0 to 100 solid parts by mass.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION [Substrate] As the substrate according to the present invention, either a transparent material or an opaque material may be adopted. When a transparent sheet of polyethylene terephthalate is used as the substrate, it is possible to protect the printed surface by attaching a reverse image of a normal printed image to an opaque adherend after printing. When an opaque sheet such as paper is used as the base material, the printed surface can be protected by sticking it on a transparent adherend after printing a normal printed image. Further, in the opaque base material, a constitution is adopted in which the other surface not provided with the delayed tack layer is made to have ink jet recording suitability. That is, by printing on both sides of the base material and then sticking it to a transparent adherend, the printed surface can be identified from either side of the adherend. Examples of such applications include labels for glass containers.

[Cushion Layer] The cushion layer is a layer for absorbing unevenness on the surface of the base material having unevenness to obtain good characters and images, and a known elastic material can be used for this. For example, styrene-butadiene latex and vinyl acetate latex are preferable. A particularly desirable cushion layer is defined in JIS-K-6301 1
Resins having a 00% modulus of 100 kg / cm ² or less, for example, SBR, MBR, polyurethane resin, polybutadiene resin, polyacrylate resin, epoxy resin, polyamide resin, rosin-modified phenol resin,
Examples thereof include terpene phenol resin and ethylene-vinyl acetate copolymer resin.

When such a cushion layer is formed, the cushioning property of the delayed tack type pressure-sensitive adhesive sheet is greatly improved, and the adhesiveness is improved when it is attached to a surface having irregularities, so that the image receiving surface having poor planarity is obtained. It is possible to form well without distortion of characters and images. Such a delayed tack type adhesive sheet is not limited to cans, bottles, boxes and the like having unevenness on the surface, and IC cards having IC chips inserted between layers and having unevenness, magnetic cards, highway cards, department stores,
It can be widely used for various prepaid cards, stored fair cards, commuter passes, ID cards, cash cards (bank cards) used in supermarkets and the like.
Further, this delayed tack type adhesive sheet can of course form characters and images excellent in image storability on a surface having low smoothness such as plain paper and coated paper as well as cards.

The thickness of the cushion layer is, for example, 1 to 90.
μm, preferably about 3 to 70 μm,
It is about 5 to 50 μm (particularly about 5 to 30 μm).

[Ink Receiving Layer] As a constituent component of the ink receiving layer according to the present invention, silica, colloidal silica,
Surface treated cationic colloidal silica, alumina sol,
Inorganic pigments such as cationic aluminum oxides or hydrates thereof, pseudo-boehmite, aluminum silicate, magnesium silicate, magnesium carbonate and the like can be mentioned.

In addition to the above-mentioned components, the constituent components of the ink receiving layer according to the present invention include commonly used aqueous polymer binders such as polyvinyl alcohol, silyl-modified polyvinyl alcohol, vinyl acetate, oxidized starch, etherified starch, Cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, casein, gelatin, soybean protein, etc .; Maleic anhydride resin, styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer, etc., conjugated diene copolymer aqueous binder; acrylic acid Acrylic polymer aqueous binder such as ester or methacrylic acid ester polymer or copolymer, acrylic acid and methacrylic acid polymer or copolymer; vinyl polymer aqueous binder such as ethylene vinyl acetate copolymer; or these Aqueous binders of functional polymers modified with functional group-containing monomers such as carboxyl groups of various polymers; Aqueous binders of thermosetting synthetic resin such as melamine resin and urea resin; Polymethylmethacrylate, polyurethane resin, unsaturated polyester Examples thereof include resins, vinyl chloride-vinyl acetate copolymers, polyvinyl butyral, alkyd resins, and other synthetic resin binders, and at least one or more types can be used. Further, a cationic resin may be used together for the purpose of fixing the dye contained in the inkjet ink.

The mixing ratio of the aqueous polymer binder is preferably in the range of 5 to 50 parts by mass with respect to 100 parts by mass of the inorganic pigment. If the mixing ratio is less than this range, the surface of the ink receiving layer is easily cracked, the gloss is lowered, the dot reproducibility is deteriorated, and an image with high sharpness cannot be obtained, which is not preferable. On the other hand, if it exceeds this range, the ink absorbency is lowered, which is not preferable.

In addition to the above components, the ink receiving layer according to the present invention may further contain an organic pigment, a hardener, an antiseptic, a dye, an ultraviolet absorber, an antioxidant, a pH adjuster, an antifoaming agent, etc. Various additives can be added.

In the present invention, the solid plasticizer which is added to the ink receiving layer and has a delayed tack function includes
Diphenyl phthalate, dihexyl phthalate, dicyclohexyl phthalate, dihydroabietyl phthalate, dimethyl isophthalate, sucrose benzoate, ethylene glycol dibenzoate, glyceride tribenzoate, pentaerythritol tetrabenzoate, sucrose octaacetate, citric acid The melting point of tricyclohexyl, etc., catechol dipalmitate, catechol distearate, catechol dibenzoate, stearyl stearate, behenylic acid monoglyceride, stearic acid monoglyceride, etc. is about 40 to 130 ° C.
Although various ester compounds within the range are listed, these are used as an aqueous dispersion after being atomized by a wet or dry pulverization method. Also, instead of the above solid plasticizer,
Liquid plasticizers such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate and dibutyl maleate can also be used as the solid plasticizer according to the present invention if they are microencapsulated to make them apparently solid.

In the present invention, a thermoplastic resin emulsion having a glass transition temperature (Tg) of 20 ° C. or lower, preferably 0 ° C. or lower is used as the pressure-sensitive adhesive which is added to the ink receiving layer and has a delayed tack function. , For example, acrylic acid ester copolymer, styrene-acrylic acid ester copolymer, styrene-butadiene copolymer, ethylene-
Vinyl acetate copolymer, vinyl acetate-acrylic acid ester copolymer, ethylene-vinyl chloride copolymer, ethylene-
Examples of the resin include acrylic acid ester copolymers, ethylene-acrylic acid copolymers, polybutadiene, and polyurethane. These may be used alone or in combination.

In the present invention, the tackifier for adding a delayed tack function to the ink receiving layer is
For example, terpene resin, aliphatic petroleum resin, aromatic petroleum resin, coumarone-indene resin, styrene resin, phenol resin, terpene-phenol resin, rosin derivative (rosin, polymerized rosin, hydrogenated rosin and their glycerin, penta Examples thereof include esters with erythritol and the like, resin acid dimer and the like.

The mixing ratio of the tackifier in the ink receiving layer of the present invention is 50 to 250 with respect to 100 parts by mass of the solid adhesive.
A range of parts by mass is preferred. When the mixing ratio is less than this range, the tackiness is extremely poor, and when it exceeds this range, the composition becomes too hard and the tackiness is poor. The mixing ratio of the solid plasticizer is 100 parts by mass of the solid adhesive,
The range of 50 to 500 parts by mass is preferable. If the mixing ratio is less than this range, blocking becomes extremely likely to occur,
If it exceeds this range, the adhesive strength tends to decrease and choking tends to occur.

In the present invention, the mixing ratio of the inorganic pigment in the ink receiving layer is 10 with respect to 100 parts by mass of the adhesive.
The range of 100 to 100 parts by mass is preferable. When the mixing ratio is less than this range, bleeding is likely to occur in the inkjet image, and when it exceeds this range, the adhesive strength is lowered.

In the delayed tack type pressure-sensitive adhesive sheet of the present invention, the coating amount of the ink receiving layer varies depending on the kind of the substrate and the composition of the coating liquid, but the dry coating amount is usually 3 to 50 g / m ^2.
It is coated in the range of.

The drying temperature after coating is set to 50 ° C. or lower, preferably 40 ° C. or lower. If the drying temperature is higher than that, the delayed tack layer is activated and develops tackiness, which is not preferable.

The delayed tack type pressure-sensitive adhesive sheet of the present invention is activated by being heated for a short time with a heater, a hot air burner, a heat stamp or the like, and exhibits tackiness. The activation time is preferably in the range of 1 to 30 seconds. Activation is carried out at a temperature 5-10 ° C below the melting point of the solid plasticizer.

[0028]

EXAMPLES The present invention will now be described with reference to examples, but the contents of the present invention are not limited to the examples. In addition,
The% and the number of parts described in the examples indicate solid mass.

Example 1 Dicyclohexyl phthalate 130 as a solid plasticizer
Parts, 100 parts of ethylene / vinyl acetate copolymer as an adhesive, 60 parts of rosin-based resin as a tackifier, and colloidal silica (average particle size of about 0.01 μm) as an ink absorbing medium.
m) 80 parts were uniformly mixed to prepare an ink receiving layer coating liquid. Urethane resin paint as a cushion layer on a base paper of LBKP having a basis weight of 85 g / m ² and a thickness after drying 1
The coating solution was dried to a thickness of 5 μm, and the coating liquid for the ink receiving layer having the above composition was coated thereon so that the dry coating amount was 20 g / m ² and dried at 40 ° C. An adhesive sheet was produced.

Example 2 Dicyclohexyl phthalate 130 as a solid plasticizer
Parts, 100 parts of an ethylene / vinyl acetate copolymer as an adhesive, 60 parts of a rosin-based resin as a tackifier, 80 parts of colloidal silica (average particle diameter of about 0.01 μm) as an ink absorbing medium of the ink receiving layer, and an adhesive. Aqueous polymer binder (10% aqueous solution of polyvinyl alcohol) 10
An ink receiving layer coating liquid was prepared by uniformly mixing 0 parts.
15 μm in thickness after drying urethane resin coating as a cushion layer on base paper made of LBKP having a basis weight of 85 g / m ^2.
To obtain a delayed tack-type pressure-sensitive adhesive sheet. The coating solution for the ink-receiving layer having the above composition was applied thereon so that the dry coating amount was 30 g / m ² , and dried at 40 ° C. .

Example 3 Dicyclohexyl phthalate 130 as solid plasticizer
Parts, 100 parts of ethylene / vinyl acetate copolymer as an adhesive, 60 parts of a rosin-based resin as a tackifier, and 150 parts of colloidal silica (average particle size about 0.01 μm) as a medium for absorbing ink in the ink receiving layer. To prepare an ink receiving layer coating liquid. Bg 85g / consisting of LBKP
A urethane resin coating material as a cushion layer is applied to m ² base paper so that the thickness after drying is 15 μm, and dried, and then a coating solution of the above formulation is applied to a dry coating amount of 30 g / m ^2. Application and drying at 40 ° C. to produce a delayed tack type pressure-sensitive adhesive sheet.

Example 4 Instead of colloidal silica (average particle size of about 0.01 μm) as the medium for absorbing ink in the ink receiving layer in Example 1, silica was used as a recording medium for absorbing ink (average particle size of 1.0 μm). A delayed tack-type pressure-sensitive adhesive sheet was produced in exactly the same manner except that (1) was used.

Example 5 A delayed tack type pressure-sensitive adhesive sheet having an ink receiving layer was prepared in the same manner as in Example 1 except that a polyethylene terephthalate film having a thickness of about 100 μm was used as the substrate.

Example 6 A delayed tack type pressure-sensitive adhesive sheet was prepared in the same manner as in Example 3 except that 5 parts of colloidal silica was used instead of 150 parts of colloidal silica which is the medium for absorbing ink used in Example 3. Was produced.

Comparative Example 1 Dicyclohexyl phthalate 130 as a solid plasticizer
Parts, 100 parts of an ethylene / vinyl acetate copolymer as an adhesive, and 60 parts of a rosin-based resin as a tackifier are uniformly mixed to prepare a coating solution, and a cushion is applied to a base paper of LBKP having a basis weight of 85 g / m ² A urethane resin coating is applied as a layer so as to have a thickness after drying of 15 μm and dried, and then a coating solution having the above composition is applied so that a dry coating amount becomes 15 g / m ² and dried at 40 ° C. Thus, a delayed tack type pressure-sensitive adhesive sheet was produced.

Comparative Example 2 Comparative Example 2 was prepared in the same manner as in Example 1 except that the cushion layer was not provided.

[Adhesive Strength] The delayed tack type pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were 30% in an atmosphere of 80 ° C.
After the adhesiveness was developed by heating for 2 seconds, it was immediately attached to a transparent glass plate having irregularities and the 180 ° peeling force was measured and evaluated according to the following criteria. Δ or more is practically usable. A: 800 g / 25 mm or more C: 300 g / 25 mm or more and less than 800 g / 25 mm X: 300 g / 25 mm or less

[Ink Absorbency] The printed surface was evaluated by rubbing the image area with a finger 5 minutes after printing with an inkjet printer (BJC-600J; manufactured by Canon Sales Co., Ltd.), and the ink absorbency was evaluated according to the following criteria. did. ○: Good △: Within practical limit ×: Poor

[Character Distortion] Evaluation Character distortion on a glass plate having unevenness of characters was visually evaluated. The evaluation criteria are as follows. Δ or more can be practically used. ◯: No distortion of characters was observed. Δ: Some character distortion was observed, but even surface irregularities were not recognized. X: Distortion of characters was clearly observed along the irregularities on the surface.

[0040]

[Table 1]

In Examples 1 and 2, the addition ratio of the inorganic pigment to the pressure-sensitive adhesive was proper. In Example 1, no aqueous polymer binder was added, and in Example 2, the adhesive force and ink absorbability were both added. Was good. In Example 3, the adhesive force was slightly lowered when the addition ratio of colloidal silica was higher than that of the pressure-sensitive adhesive. On the other hand, in Example 6, the ink absorptivity was slightly lowered when the addition ratio of colloidal silica was low. In Example 4, when the colloidal silica was replaced with silica having a large average particle size (average particle size 1.0 μm), the ink absorbency was slightly lowered. In Example 5, when a polyethylene terephthalate film was used as the substrate instead of paper, the adhesive strength and ink absorbency were good, and in this case, the printed characters and images could be recognized through the transparent film.

Comparative Example 1 has a constitution in which no inorganic pigment is added to the ink receiving layer. In this constitution, although the adhesive force at the time of heat activation was sufficient, almost no ink absorption was observed. Since the cushion layer was not provided in Comparative Example 2, distortion of the characters was recognized.

[0043]

According to the present invention, a delayed tack type pressure-sensitive adhesive sheet capable of printing on the pressure-sensitive adhesive surface can be obtained by imparting the delayed tack property to the surface of the substrate on which the ink receiving layer is provided. INDUSTRIAL APPLICABILITY The delayed tack type pressure-sensitive adhesive sheet of the present invention can be used as a label or tape which is required to have durability and water resistance particularly on an uneven surface.

Claims (3)

[Claims] 1. A cushion layer and an ink receiving layer containing an inorganic pigment are laminated on at least one surface of a substrate,
Further, a delayed tack type pressure-sensitive adhesive sheet comprising a solid plasticizer, a pressure-sensitive adhesive and a tackifier in the ink receiving layer. 2. The delayed tack type pressure-sensitive adhesive sheet according to claim 1, wherein the cushion layer is a layer containing as a main component a resin having a 100% modulus defined by JIS K6301 of 100 Kg / cm ² or less. 3. The mixing ratio of the inorganic pigment and the pressure-sensitive adhesive contained in the ink receiving layer is in the range of 10 to 100 solid parts by mass of pigment with respect to 100 parts by mass of solid adhesive. The delayed tack type pressure-sensitive adhesive sheet according to 2.