JPH0815810B2 - Protective sheet for information recording paper - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a protective sheet for information recording paper such as heat-sensitive recording paper and pressure-sensitive recording paper, and more particularly to protecting a colored printing layer of the information recording paper. The present invention relates to a protective sheet having adhesiveness for

[Prior Art and Problems Thereof] In recent years, the use of heat-sensitive recording paper, pressure-sensitive recording paper, etc. has increased with the spread of facsimiles, copy-type business forms and the like in office work.

These heat-sensitive recording papers, pressure-sensitive recording papers, etc. are prepared, for example, by applying a dye precursor to a base paper and forming it, and the dye precursor reacts with heat or pressure applied from the outside to develop a color, and a character or a figure is drawn. Is formed and recorded (hereinafter, the paper in which the dye precursor in the base paper is converted into the dye by the action of heat or pressure and the characters or figures are displayed is referred to as "information recording paper").

Since the color development of such information recording paper is based on a chemical reaction, the action of oxygen and moisture in the air, heat, light,
It has the drawback that it discolors due to oil, solvent, etc. and is difficult to store for a long time.

In order to overcome this drawback of the information recording paper, various methods have been tried in the past.

For example, first, a method of laminating the information recording paper itself with a normal heat-fusible film or the like is conceived, but since the laminating method applies heat and pressure, the entire lamination is colored by the laminating process and is meaningless at all.

Therefore, a method of laminating using a transparent pressure-sensitive adhesive film for laminating was developed, but this method has a drawback that the color-developed portion is economically discolored by the action of the pressure-sensitive adhesive used in the pressure-sensitive adhesive tape.

In order to solve the problem of discoloration due to this adhesive film, attempts have been made to introduce an organic acid having a function as a color developer into the adhesive, but it is not very effective and the problem that the non-colored part develops color For this reason, satisfactory results have not been obtained.

On the other hand, some methods of coating a protective agent on the surface of the information recording paper have been proposed, but none of them have a sufficient protective function.

[Means for Solving the Problems] The inventors of the present invention have conducted earnest research to develop a method for stably protecting information recording paper. As a result, they have found that the drawbacks that occur when the pressure-sensitive adhesive film for laminating is used are due to the fact that an acrylic adhesive is generally used as the adhesive from the viewpoint of weather resistance.

Therefore, as a result of searching for an adhesive having weather resistance equivalent to that of the acrylic adhesive and having no influence on the coloring dye in the printing layer of the information recording paper, a specific tackifying resin and a saturated polyolefin elastomer are found. Has been found to satisfy this condition, and has completed the present invention.

That is, the present invention is based on 100 parts by weight of a base polymer selected from polyolefin and styrene-polyolefin copolymer elastomer, and 5 to 400 parts by weight of a petroleum resin having a Gardner number of 2 or less, a hydrogenated terpene resin and a hydrogenated resin. It is intended to provide a protective sheet for information recording paper, which is obtained by applying a pressure-sensitive adhesive layer containing at least one kind of tackifying resin selected from rosin resins onto a transparent substrate.

Among the components forming the pressure-sensitive adhesive layer, examples of the polyolefin elastomer used as the base polymer include polyisobutylene rubber and hydrogenated polyisoprene rubber.

Examples of styrene-polyolefin copolymer elastomers include copolymers containing 5 to 50% styrene and 95 to 50% polyolefin, and more specifically, styrene / ethylene / propylene block polymers (SE
P), styrene / ethylene / propylene / styrene block polymer (SEPS), styrene / ethylene / butylene / styrene block polymer (SEBS) and the like.

These base polymers are preferably those which do not affect the heat-sensitive layer and the pressure-sensitive layer, do not cause discoloration or color development, and have good weather resistance themselves, and which are resistant to yellowing, whitening and curing, and particularly shown below. It is desirable to have such properties.

 When made into a film, it should be colorless and transparent.

 SP value is as low as 8.5 or less.

It should be soluble in solvents such as toluene and hexane, or its viscosity should drop significantly at high temperatures (it can be hot melted).

No or few unsaturated bonds in the olefin part.

Examples of the resin used as the tackifying resin for the adhesive layer include C ₅ , C ₉ or C ₅ / C ₉ petroleum resin having a color number of Gardner number 2 (hereinafter abbreviated as “G2”) or less, or its water addition. Compounds, hydrogenated terpene resins such as terpene resins or hydrogenated products of monoterpene / aromatic copolymers, hydrogenated rosin resins such as hydrogenated products of rosin esters or polymerized rosin esters, and the like.

Of these, hydrogenated resins are preferable because they have good weather resistance and little hardening and softening of the pressure-sensitive adhesive.

This tackifying resin is a base polymer 10
It is added in an amount of 5 to 400 parts by weight, preferably 50 to 200 parts by weight, based on 0 part by weight.

In the pressure-sensitive adhesive layer of the protective sheet of the present invention, in addition to the above-mentioned two components, a softening agent such as low molecular weight isobutylene, polybutene, process oil, paraffin wax, and hindered phenol type, in addition to the above-mentioned two components. An antioxidant such as benzophenone or an ultraviolet absorber such as benztriazole or the like can be added.

The transparent base material as the base material of the protective sheet of the present invention is transparent and has good weather resistance, is resistant to yellowing and whitening, and may be any material that is resistant to being attacked by water, oil and the like, for example, polyester, Polyethylene, polypropylene, polyvinyl chloride, polycarbonate film and the like can be used.

As a method of applying the pressure-sensitive adhesive layer to the transparent substrate, a generally used method can be adopted, and examples thereof include the following method.

Each component constituting the pressure-sensitive adhesive layer is dissolved in a solvent such as toluene or hexane and mixed to prepare an appropriate viscosity, which is then coated on a separator, the solvent is volatilized and then transferred to a transparent substrate. Alternatively, it may be directly applied to a transparent substrate having a back surface subjected to a peeling treatment, volatilized with a solvent, and then wound up.

When a styrene-polyolefin copolymer elastomer is used, its hot melt property is utilized, and each component constituting the pressure-sensitive adhesive layer is mixed in a hot melt state, and this mixture is transferred or directly coated by a hot melt applicator.

The thickness of the pressure-sensitive adhesive layer applied to the transparent substrate can be arbitrarily determined, but generally, it is preferably about 10 μm to 30 μm.

[Action and Effect of Invention] The excellent action of the protective sheet for information recording paper of the present invention is due to the synergistic action of the polyolefin resin adopted in place of the acrylic resin and the tackifying resin constituting the adhesive layer. it is conceivable that. That is, the polyolefin-based resin has weather resistance not inferior to the acrylic resin, and does not affect the leuco-based compound that is a pigment generally used for thermal paper and pressure-sensitive paper, Further, since the tackifying resin is also colorless and transparent, has good adhesiveness, and has good stability over time, it is possible to store characters, figures, etc. recorded on the information recording paper as they are for a long period of time. is there.

Therefore, the information recording paper protection sheet can be advantageously used when it is necessary to store the contents received by facsimile, important documents created by copying paper, etc. for a long period of time.

EXAMPLES Next, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to these examples.

Example 1 A pressure-sensitive adhesive composition was prepared with the composition and blending amount shown in Table 1 below, and 100 g thereof was dissolved in 140 ml of toluene. This toluene solution is applied to a polyethylene terephthalate film having a thickness of 25 μm so that the pressure-sensitive adhesive layer is 25 μm, and the temperature is 80 ° C.
And dried for 2 minutes to prepare an adhesive sheet.

The pressure-sensitive adhesive sheet thus obtained was examined for adhesiveness, heat sensitivity, surface protection of pressure-sensitive paper, and resistance to UV irradiation by the following methods. The results are shown in Table 2.

(1) Adhesiveness: Adhesiveness was examined according to the 180 degree peeling test method described in JIS Z0237.

That is, using a SUS plate as an adherend, attach a pressure-sensitive adhesive sheet set to a sample width of 20 mm to this plate, and after 24 hours, use a load cell type tensile tester to remove at a speed of 300 m.
The resistance value when the adhesive sheet was peeled off was measured at m / min, and the average value was expressed in units of g / 20 mm.

(2) Surface protection of heat and pressure sensitive paper: A sample adhesive sheet with a width of 50 mm and a length of 200 mm was attached to a printed A-4 size FACOM FIIX thermal recording paper (Fujitsu Ltd.) at 50 ° C, The sample was left to stand in a constant temperature bath kept at 80% humidity for 5 days, and the print definition was visually compared.

As the pressure-sensitive recording paper, general office slip paper was used, and this was uniformly pressed with a rubber roller to develop a color, and then the surface protection was examined in the same manner as the heat-sensitive recording paper.

(3) Resistance to UV irradiation: The sample pressure-sensitive adhesive sheet was irradiated with ultraviolet rays for 40 hours using a W-O-meter under the condition of 50 ° C / 80% humidity. After the irradiation, yellowing and whitening of the pressure-sensitive adhesive sheet were visually determined.

Adhesive composition: result: Comparative Example 1 According to the disclosure of JP-A-63-278989, a pressure-sensitive adhesive composition was prepared with the following composition and blending amount, and then a pressure-sensitive adhesive sheet was prepared according to Example 1.

With respect to the obtained pressure-sensitive adhesive sheet, its adhesiveness, surface protection of thermal paper and resistance to UV irradiation were examined by the method described in Example 1. The results are as follows.

(Composition) SIS ^* 100 parts by weight Hydrogenated terpene ^** 40 parts by weight * Califlex TR1112 ** Clearon P105 (Result) Adhesion: 500g / 200mm The adhesion after UV irradiation for 48 hours became 0.

Thermal paper fading test: No fading was visually observed, but color development was observed in the non-recorded area.

UV resistance: Whitening was visually observed.

As is clear from the above results, the protective sheet for information recording paper of the present invention has sufficient adhesiveness, has a sufficient protective effect, and does not fade even when irradiated with ultraviolet rays.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication C09J 7/02 JJV JJY JKE JLF

Claims (2)

[Claims] 1. A base polymer selected from 100 parts by weight of a polyolefin elastomer and a styrene-polyolefin copolymer elastomer, and selected from 50 to 200 parts by weight of a hydrogenated petroleum resin, a hydrogenated terpene resin and a hydrogenated rosin resin. A protective sheet for information recording paper, which is obtained by applying a pressure-sensitive adhesive layer containing at least one kind of tackifying resin on a transparent substrate. 2. The base polymer is styrene / ethylene /
The information recording paper according to claim 1, which is selected from propylene block polymer, styrene / ethylene / propylene / styrene block polymer, styrene / ethylene / butylene / styrene block polymer, polyisobutylene rubber and hydrogenated isoprene rubber. Protective sheet.