JPS63186793A - Pressure-sensitive adhesive sheet - Google Patents

Abstract

PURPOSE:To provide the title sheet which is entirely free from blocking during storage or treatment under a high-temp. body and adheres with excellent adhesion strength upon application of a high pressure and which comprises a sheet material and, formed thereon, an adhesive layer comprising a pressure-sensitive adhesive, a pigment, a tackifier and a mold releasing agent. CONSTITUTION:100pts. (dry wt.; the same shall apply hereinafter) pressure- sensitive adhesive (a) such as a natural rubber resin excellent in autohesion is compounded with 100-600pts. pigment (b) comprising inorg. or org. particles not exhibiting pressure-sensitive or heat-sensitive adhesion, such as particles of silica, TiO2, clay, talc or a melamine resin having an average particle diameter of 8mum or less, 50-300pts.wt. tackifier (c) such as a rosin (deriv.) and 5-50pts. polyolefin wax (d) (e.g., aq. PE wax emulsion) as a mold releasing agent. When desired, the viscosity of the compd. is regulated with CMC. Thus, there is obtd. a pressure-sensitive adhesive water-base ink (A). The component (A) is applied or printed on a wood-free paper (B) or various synthetic papers in such a manner that the coating thickness is 5-20mum.

Description

[Detailed description of the invention] (A> Industrial application field The present invention relates to pressure sensitive adhesive sheets.

More specifically, when the adhesive layers provided on the sheet are faced to each other and pressed with strong pressure, they have good adhesive strength. (a) The adhesive layer and the support to which no adhesive is applied When the sheets are facing each other and pressurized (B) When the adhesive layers are in contact with each other or when pressurized with a light load (C) When the adhesive layer is in contact with a high-temperature body, there is no adhesive or tackiness at all. The present invention relates to a pressure-sensitive adhesive sheet that does not exhibit blocking properties.

(B) Prior Art Various natural and synthetic adhesive resins having pressure-sensitive adhesive properties are known. These resins are applied as pressure-sensitive adhesive tapes by printing or coating on film or paper as a support, and are commercialized as adhesive tapes, cellophane tapes, etc., for example. These adhesives have various types of adhesive resin, support, and adhesive strength depending on the purpose of use, and are commonly used on a daily basis. In recent years, sheets for business forms have been printed or coated with pressure-sensitive or heat-sensitive adhesives, which are stacked so that each adhesive layer faces each other, and then bonded by applying strong pressure or heating. Demand for pressure-sensitive adhesive sheets and heat-sensitive adhesive sheets for processing into slips, forms, envelopes, postcards, etc. is increasing, and they are also introduced in literature publications.

(C) Problems to be Solved by the Invention These pressure-sensitive adhesive sheets and heat-sensitive adhesive sheets are subjected to various printing, cutting, packaging, and bending processes during the manufacturing and processing process.

In addition, the use of electrophotographic printers for printing has recently increased, and in this process, it is essential to fix the toner using a high-temperature body, so thermoplastic adhesives are practically used. It's impossible.

In other words, in an electrophotographic printer, a heating element is required to fix the toner, and the sheet is inevitably exposed to high heat, and when the adhesive layer on the sheet comes into contact with the heating element, blocking occurs. Jamming (paper jam)
If this occurs and is severe, it can cause considerable damage to the machine.It is clear that such troubles are unavoidable when heat seal type adhesives are used.

However, even pressure-sensitive adhesives exhibit thermoplasticity to some extent depending on the type of resin, and essentially, if they are exposed to high heat, they are subject to the phenomenon of failure. In addition, even if no heat is applied, blocking will inevitably occur if the adhesive layers are in contact with each other under a light load, or if the adhesive and the support sheet are stored for a long time in contact with each other.
This may become an unfavorable phenomenon in handling operations in the next process.

To address these problems, Japanese Patent Laid-Open No. 61-34552,
1-35279, 61-34550, 6l-345
In 5L Publication No. 61-34552, etc., by adding inorganic or organic pigments (so-called anti-blocking agents) that are not thermoplastic and do not have pressure-sensitive adhesive properties, it is possible to bond papers to each other or to fuse them to high-temperature bodies. It is stated that this method prevents this and improves running performance during printing.

However, these pigments inherently reduce adhesive strength, and the amounts added as described in the above-mentioned publications are insufficient to completely eliminate blocking.

Furthermore, in JP-A-61-34553@, it is described that silicone-based paraffin wax-based lubricants, metal soap-based lubricants, and t!Ji type agents are added as materials to prevent blocking and heat fusion. As in the case of pigments, these also cause a considerable decrease in adhesive strength, and no matter what adhesive they are combined with, a satisfactory bonding point could not be produced.

In view of the above-mentioned problems, the present invention aims to provide a pressure-sensitive adhesive sheet with good adhesive strength.

More specifically, (1) when the adhesive layer and the support sheet to which no adhesive is applied are facing each other and pressurized, (2) when the adhesive layers are in contact with each other or when pressurized with a light load. ,(
3) To provide a pressure-sensitive adhesive sheet that does not cause any odor blocking when the adhesive layer comes into contact with a high-temperature body.

(D) Means for Solving the Problems The present invention basically involves adding and mixing the four types of adhesive, pigment, tackifier, and mold release agent that form the pressure-sensitive adhesive layer within a specific range. By setting this, a pressure-sensitive adhesive sheet (7) can be obtained which exhibits sufficient adhesive strength when pressed and which does not cause any blocking even when exposed to any harsh conditions.

The adhesive used in the present invention can be used as long as it has pressure-sensitive adhesive properties, and preferred examples include natural rubber resin, acrylic resin, styrene-butadiene resin, and synthetic rubber resin. Particularly preferred examples include natural rubber-based resins that have excellent self-adhesive properties. These resins can be mixed as long as the adhesive strength is not reduced.

Pigment refers to inorganic or organic particles that do not exhibit pressure-sensitive or heat-sensitive adhesive properties. Specifically, silica, kaolin, calcium carbonate, titanium oxide, aqueous aluminum, zinc white, clay, talc, melamine particles, melamine resin particles,
Examples include benzoguanamine particles, starch particles, etc., and particularly preferable examples include those with an average particle diameter of 8 μm or less and wrinkle strength in consideration of dispersibility, antiblocking properties, printability, etc.

Various adhesive agents are known, and one that is most compatible with the adhesive and pigment may be selected.

Specific examples of tackifiers include rosin resins and their derivatives, terpene resins, terpene phenol resins, C5 petroleum resins, C9 petroleum resins, styrene resins, alkylphenol resins, xylene resins, and chromalone indene resins. In the present invention, rosin resins are particularly preferred.

Various mold release agents are known and can be classified as follows. Examples of hydrocarbon waxes include various paraffin waxes, microwaxes, and polyolefin waxes, as well as fatty acid-based waxes, fatty acid amide-based waxes, ester-based waxes, alcohol-based waxes, metal soap-based waxes, and silicone-based waxes. In the present invention, polyolefin wax is preferred as a mold release agent, and polyethylene wax aqueous emulsion is particularly preferred.

This product not only showed an excellent effect in preventing blocking, but also showed no decrease in adhesive strength at all when added in a certain amount.

The mixing ratio of these components is approximately 100 to 600 parts of pigment, preferably 250 to 600 parts of pigment to 100 parts of adhesive (ω for drying).
450 parts, 50 to 300 parts of the tackifier, more preferably 80 to 200 parts, and a range of 5 to 50 parts of the polyolefin wax emulsion as a release agent to obtain the maximum adhesive strength and prevent blocking. It also did not occur. If the amounts of the pigment, tackifier, and release agent are added outside this range, the balance between adhesive strength and blocking property will be lost, resulting in trouble.

The support for the pressure-sensitive adhesive sheet is not particularly limited, and high-quality paper mainly composed of cellulose fibers and various synthetic papers can also be used.

The appropriate thickness for applying the pressure-sensitive adhesive ink is in the range of 5 to 20 microns. Preferred examples of the coating L1 printing method include air coating, if coating, blade knife coating, flexo printing, and screen printing. It is also possible to add thickeners, dispersants, foaming agents, preservatives, anti-deterioration agents, etc. to the composition, if necessary.

(E) Example The present invention will be explained in more detail with reference to Examples.

The weights shown in Examples and Comparative Examples all indicate the number of shoes in a dry and dehydrated state.

Example 1 Nisudyne #MS-32 (manufactured by Tsukisui Chemical Co., Ltd., natural rubber latex) 'too part' was used as a pressure-sensitive adhesive, and Mizukasil P-832 (manufactured by Mizusawa Chemical Co., Ltd., synthetic silica,
Average particle size: 350 parts, 5N-T as a tackifier
ACK (manufactured by San Nopco, rosin-based tackifier) 140
and 20 parts of polyethylene]/wax emulsion Hytic E-4B (manufactured by Toho Chemical Industry Co., Ltd.) as a mold release agent, and the non-volatile content concentration was adjusted to 50%. °C (60 rpm) to obtain a pressure-sensitive adhesive water-based ink.This ink was flexographic printed on the edges of a piece of high-quality paper with a basis weight of 1507/end to a width of 3M and a thickness of 8μm for making envelopes. A pressure-sensitive pipe-welding sheet was obtained. After bending this sheet so that the adhesive layers faced each other, a rigid calender roll was used to bend the sheet to 100 kg/cm.
When pressurized with the same pressure, an envelope was instantly obtained.

Example 2 The same Nisdyne #MS-3 as in Example 1 was used as a pressure sensitive adhesive.
2 Jilton M-42 (manufactured by Mizusawa Chemical Co., Ltd., semi-synthetic silica, average particle size 7) as a pigment per 100 parts.

430 parts of 0, m), 200 parts of Rika Vercules ID-188 (rosin-based tackifier) as a tackifier,
30% of Hytic E-4B, the same as in Example 1, was used as a mold release agent.
Partial mixing was performed to adjust the nonvolatile content to 50%. Furthermore, using commercially available carboxymethyl cellulose, the viscosity was increased to 1800 cps.
A pressure-sensitive adhesive water-based ink was obtained.

When this ink was processed into general high-quality paper and subjected to pressure treatment in the same manner as in Example 1, it had sufficient adhesive strength to cause paper layer destruction, and there was no blocking at all in the adhesive printed area.

Example 3 Acrylic emulsion AE-944 (manufactured by Japan Synthetic Rubber Co., Ltd., acrylic emulsion) '100 as adhesive
300 parts of papermaking talc as a pigment, Cellosol #8-523 as a tackifier (>90 parts of Terpene Phenol Resin Emulsion manufactured by Middle East Yushi Co., Ltd.), and an aqueous emulsion of Jeng Wax 16'1-P (Sanyo Chemical Co., Ltd.) as a mold release agent. Polyethylene wax emulsion manufactured by Kogyo Co., Ltd.)
The non-volatile content was adjusted to 52% by adding 25 parts, and the viscosity was adjusted to 18 oocp using commercially available carboxymethyl cellulose.
A pressure-sensitive adhesive ink was obtained.

When this ink was processed into high-quality paper in the same manner as in Example 1, a pressure-sensitive adhesive sheet with good adhesion was obtained.

Example 4 Styrene-butadiene latex L-14 as adhesive
32 (SBR latex manufactured by Asahi Kasei Corporation) '10
0 parts as a pigment, Eposter 5U-6 (manufactured by Nippon Shokubai Co., Ltd.) benzoguanamine particles >300 parts, as a tackifier 180 parts of CKE-2370 (manufactured by Showa Kobunshi Co., Ltd., phenolic resin emulsion), and a polypropylene wax emulsion. , Hitic E-433N (
manufactured by Toho Chemical Industry Co., Ltd. > 40 parts, the non-volatile content temperature was adjusted to 32%, and air knife coating was applied to the entire felt surface of the same high-quality paper as in Example 1 to a coating thickness of 15 μm. The pressure adhesive sheet is 17.

This sheet was cut into pieces the size of a government postcard, the coated surfaces facing each other, and a rigid calendar roll pressure of 300 kg/cm was applied.
When applied with a pressure of

Comparative Example 1 A pressure-sensitive adhesive ink was obtained in the same manner as in Example 1 except that the amount of pigment P-832 added was changed to 50 parts, and a pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1.

Comparative Example 2 A pressure-sensitive adhesive ink was obtained in the same manner as in Example 1, except that 800 parts of the pigment P-832 was added.
Furthermore, a pressure-sensitive adhesive sheet was obtained in the same manner.

Comparative Example 3 In Example 1, a pressure-sensitive adhesive ink was obtained without adding 5N-TACK, and pressure-sensitive adhesive sheets 1 to 1 were prepared in roughly the same manner as in Example 1.
I got it.

Comparative Example 4 A pressure-sensitive adhesive ink was obtained in the same manner as in Example 1, except that the amount of 5N-TACK added was 350 parts,
A pressure-sensitive adhesive sheet was obtained in the same manner.

Comparative Example 5 In Example 1, a pressure-sensitive adhesive ink was obtained without adding Hytic E-4B, and a pressure-sensitive adhesive sheet was obtained in the same manner.

Comparative Example 6 In Example 1, the amount of Hytic E-4B added was 65%.
A pressure-sensitive adhesive ink was obtained in the same manner as above, and a pressure-sensitive adhesive sheet was obtained in the same manner as above.

The pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were evaluated for adhesive properties according to the following test method.

a. Adhesiveness The adhesive force when pressed with a rigid calendar roll was evaluated in two levels: pressure force of 100 Kg/cm and 300 Kg/cm.

Judgment criteria Q20: Paper layer destruction occurs.

Δ　Does not cause paper layer destruction but adheres well are doing.

× indicates almost no adhesion b, light load blocking properties Layer the sheets so that the coated surfaces are facing each other, and
Evaluate the blocking property after applying a light load of Kg/ctrt and leaving it at room temperature for 72 hours Judgment criteria Q: ○ No blocking at all △ Some blocking × Severe blocking C9 Heat blocking adhesive layer coated surfaces should face each other. The blocking property was evaluated when the sheets were brought into contact with each other and sandwiched between the coated surfaces for 10 seconds using a household iron heated to 200'C from above and below the sheet.

Judgment criteria: d, same as light load blocking property; Copying: 1q pressure-sensitive adhesive sheets of Examples and Comparative Examples were cut into 8-4 size, and the copies were made using an RPC copying machine 437 manufactured by Fuji Xerox Co., Ltd.
Evaluate running performance when treated with Type 0. Judgment criteria:○
Table 1 summarizes the evaluation results of "Possible to print without problems" and "Possible or higher" such as printing quality and runnability.

(F) Effect of the invention As is clear from the examples, the present invention claims that the mixing ratio of the adhesive, pigment, tackifier, and release agent, which are the components of the adhesive layer on the pressure-sensitive adhesive sheet, is By setting the adhesive strength within this range, it is possible to obtain a pressure-sensitive adhesive sheet that has excellent adhesive strength and does not cause any blocking during storage or processing under a high-temperature body. This means that the pressure-sensitive adhesive sheet according to the present invention will not cause any trouble under any processing conditions encountered during actual use, and can be very useful industrially.

Claims (5)

[Claims] (1) In a pressure-sensitive adhesive sheet in which the adhesive layers provided on the sheet are bonded by facing each other and applying pressure, the composition of the adhesive layer is basically 100 parts of the pressure-sensitive adhesive (
A pressure-sensitive adhesive sheet comprising 100 to 600 parts of pigment, 50 to 300 parts of tackifier, and 5 to 50 parts of polyolefin wax based on dry weight. (2) The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive is a self-adhesive natural rubber-based adhesive. (3) The pressure-sensitive adhesive sheet according to claim 1, wherein the pigment is silica having an average particle diameter of 8 μm or less. (4) The pressure-sensitive adhesive sheet according to claim 1, wherein the tackifier is a rosin resin. (5) The pressure-sensitive adhesive sheet according to claim 1, wherein the polyolefin wax is polyethylene wax.