JP2000345118A - Roll-shaped heat-sensitive adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a roll-shaped heat-sensitive adhesive sheet hardly causing blocking or decrease of adhesion of an ink of a surface substrate and excellent in preservability when preserving the heat-sensitive adhesive sheet by winding the sheet in the roll shape. SOLUTION: This roll-shaped heat-sensitive adhesive sheet obtained by forming a heat-sensitive adhesive layer containing a wax on one surface of a surface substrate and winding the obtained sheet is regulated so that the hardness of the wind-up roll of the roll-shaped heat-sensitive adhesive sheet may have 10-40 average value of rebound degree measured by a Schmidt hammer method (J. TAPPI Paper and Pulp Testing Method No.37-81).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a heat-sensitive adhesive sheet having a heat-sensitive adhesive layer on one surface of a surface substrate, and more particularly to a heat-sensitive adhesive sheet finished in a roll.

[0002]

2. Description of the Related Art A heat-sensitive adhesive sheet has a structure in which a heat-sensitive adhesive (also called a hot-melt type adhesive or a heat seal type adhesive) layer is provided on one side of a base material. As a label, it is adhered and used on a wrapping paper or a glass bottle as an adherend using a heating and pressing device such as a hot plate. The adhesive mechanism of the heat-sensitive adhesive has no adhesion at room temperature, and adheres to the adherend by melting by heating (physical anchoring by permeation into unevenness, and improvement of chemical adhesion due to increase in contact area) Then, it is solidified by cooling and adheres to an adherend.

[0003] The heat-sensitive adhesive sheet is prepared by first performing a desired printing on one side of coated paper or art paper as a surface base material, and then heating (about 100 to 200 ° C) the heat-sensitive adhesive on the other side. (Viscosity of about 1000 to 3000 cps) and a method of applying (hereinafter also referred to as a pre-printing method), and a method of applying a heat-sensitive adhesive to a surface substrate by heating, melting, and then printing (hereinafter referred to as “post-printing method”). Printing method).

[0004]

However, in the post-printing method, the heat-sensitive adhesive sheet is wound up and stored in a roll shape until printing, but there is a risk that the winding-up will be blocked during this storage. is there. For this reason, conventionally, in general, overcoating is performed after ink application at the time of printing in order to prevent blocking between the heat-sensitive adhesive layer and the ink layer by the preprinting method. Thereafter, the sheet is cut into a predetermined label size, and is labeled on an adherend by a labeler.

[0005] One of the features of the heat-sensitive adhesive sheet is that it has no adhesiveness at room temperature, so that a release sheet for protecting the pressure-sensitive adhesive layer such as a pressure-sensitive adhesive sheet is not required. On the other hand, especially in the case of the post-printing method, there is a possibility that a problem that does not exist in the adhesive sheet may occur. That is, when the heat-sensitive adhesive sheet is wound into a roll, the heat-sensitive adhesive layer comes into contact with the surface of the base material. To reduce the adhesion of the ink during printing. To solve these problems, there is a method in which a filler such as a mineral pigment is added to the heat-sensitive adhesive as an anti-blocking agent. However, at present, the decrease in ink adhesion cannot be improved and the decrease in ink adhesion cannot be improved.

The present invention provides a roll-shaped heat-sensitive adhesive sheet which is excellent in storability without blocking or a decrease in ink adhesion of a surface substrate when the heat-sensitive adhesive sheet is wound up in a roll and stored. is there.

[0007]

Means for Solving the Problems The present inventors have taken up a heat-sensitive adhesive sheet in a roll form, stored it in various environments, blocked the heat-sensitive adhesive sheet, and set the printing property (ink As a result of various studies on the adhesiveness) and the adhesive quality, it was found that there were appropriate conditions for the winding method and the smoothness of the surface of the heat-sensitive adhesive, and the present invention was completed.

That is, the present invention relates to a roll-shaped heat-sensitive adhesive sheet provided with a wax-containing heat-sensitive adhesive layer on one surface of a surface substrate, wherein the roll-shaped heat-sensitive adhesive sheet has a Schmidt hardness. A roll-shaped heat-sensitive adhesive sheet characterized by having an average value of rebound of 10 to 40 by a hammer method (J. TAPPI paper pulp test method No. 37-81). More preferably, the smoothness of the surface of the heat-sensitive adhesive layer (J. TAPPI paper pulp test method No.
5) 100 to 1000 seconds, wherein the roll-shaped heat-sensitive adhesive sheet is characterized in that:

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The heat-sensitive adhesive sheet referred to in the present invention is a sheet in which a heat-sensitive adhesive layer is provided on a surface substrate, and the composition of the heat-sensitive adhesive is, for example, ethylene vinyl acetate as a base resin. It is composed of a thermoplastic resin such as a copolymer, a tackifier such as rosin, and a wax such as paraffin. In the case of this configuration, the purpose of each compounding is to provide the base resin with cohesive force, the tackifier with adhesiveness, and the wax with fluidity during heating.

Examples of the thermoplastic resin include ethylene-vinyl acetate copolymers, ethylene-vinyl acetate-acryl copolymers, ethylene-methyl copolymers such as ethylene-methyl methacrylate and ethylene-ethyl acrylate, and styrene-butadiene. -Thermoplastic elastomers such as styrene copolymers, styrene-isoprene-styrene copolymers,
Olefin-based polymers such as polyethylene, polypropylene and amorphous polyalphaolefin, etc., having a glass transition point of about −30 ° C. to about 50 ° C. and a molecular weight of several tens
About one million to several ten million can be applied. Incidentally, when the glass transition point is lower than -30 ° C, the heat-sensitive adhesive layer exhibits tackiness even at room temperature, and a release sheet is required. On the other hand, when the glass transition point exceeds 50 ° C., the heat-sensitive adhesive layer at the time of heating is too hard, and the adhesiveness is insufficient. On the other hand, if the molecular weight is too low, the cohesive force of the heat-sensitive adhesive layer decreases, and the adhesiveness becomes insufficient. Conversely, if the molecular weight is too high, the heat-sensitive adhesive layer at the time of heating is too hard, and the adhesiveness may be insufficient. The thermoplastic resins are used alone or in combination.

Examples of the tackifier include rosin, polymerized rosin, disproportionated rosin and derivatives thereof, polyterpene resins, phenol-modified resins such as terpene phenol and rosin phenol, alkylphenol resins, and cumarone-based resins.
Indene resin, xylene resin, aliphatic hydrocarbon resin, alicyclic hydrocarbon resin, aromatic hydrocarbon resin and its hydrogenated product, styrene resin, vinyltoluene-α-methylstyrene copolymer, etc. Points from 100 ° C to 170
A temperature of about ° C is applicable. By the way, the softening point is 100 ℃
If it is less than 170, there is a problem in the preservation of the label, and
When the temperature exceeds ℃, the adhesiveness at the time of heating may decrease.
Further, the thermoplastic resins are used alone or in combination.

As the wax, paraffin wax,
Examples include petroleum waxes such as microwax, and synthetic waxes such as polyethylene wax and polypropylene wax. The melting point or softening point is from 40 ° C to 150 ° C.
Some degree is applicable. If the temperature is lower than 40 ° C., the storage stability of the heat-sensitive adhesive sheet is inferior. If the temperature exceeds 150 ° C., the fluidity of the heat-sensitive adhesive at the time of heating is reduced, and the adhesiveness may be deteriorated. The waxes can be used alone or in combination of two or more.

The mixing ratio of the thermoplastic resin, tackifier and wax is about 20 to 60% by weight, about 20 to 60% by weight, and about 20 to 60% by weight, respectively.
It is appropriately adjusted depending on the storage stability and the like, and in some cases, may be blended out of the above range.

In addition to these, an antioxidant and a filler are appropriately used. As the antioxidant, phenol-based, thioether-based, and phosphite-based antioxidants are used alone or in combination. Examples of the filler include calcium carbonate, clay, talc, barium sulfate, zinc oxide, magnesium oxide, hydrous silicic acid, silicic anhydride, and the like, and are used alone or in combination. These fillers
As described above, it also effectively acts to suppress blocking, but since the intended adhesion may be reduced depending on the amount added, it is adjusted in the range of 0 to 20% by weight, preferably 0 to 10% by weight. You.

The coating amount of the heat-sensitive adhesive is ^{2 to} 30 g / m ^{2 in} dry weight. Preferably it is 5 to 20 g / m ² . By the way, if it is less than 2 g / m ² , sufficient adhesiveness cannot be obtained. On the other hand, if it exceeds 30 g / m ² , the adhesiveness obtained will be saturated, which is not economically preferable.

As a method for applying the heat-sensitive adhesive to the substrate, a general coater provided with a heating and heat retaining device can be applied. As the coater head, a reverse roll coater,
It is performed by a roll coater such as a gravure roll coater, and various coating apparatuses such as a resin extrusion type die coater and a lip coater.

The surface substrate used in the heat-sensitive adhesive sheet of the present invention includes papers (eg, high-quality paper, art paper, coated paper, cast-coated paper, impregnated paper, laminated paper, etc.),
Synthetic paper (for example, polypropylene-based synthetic paper), films (for example, films of polyethylene terephthalate, polypropylene, polyethylene, etc.), metal foils, non-woven fabrics, woven fabrics, and the like, and sheets obtained by appropriately laminating these, include hot plate heating. When used in a mold high-speed labeler, a substrate having excellent heat resistance is preferred. Needless to say, various recording layers such as a pressure-sensitive recording layer, a thermal transfer image receiving layer, an ink jet recording layer, a pigment coating layer, a metal deposition layer, and a printing layer may be appropriately provided on the surface of these substrates. On the other hand, the surface to which the heat-sensitive adhesive is applied may be provided with a barrier layer for reinforcing the strength or preventing the heat-sensitive adhesive from penetrating into the base material and preventing the adhesive function from being deteriorated.

When used as a label, the surface substrate is required to have printability and the like. For example, a substrate on which a pigment coating layer is formed, or a substrate on which an anchor layer or an easily printed layer is formed on a film or the like is preferable. Further, in the case of a label to be attached to a glass bottle which may be immersed in water such as soft drink or liquor and refrigerated, it is preferable to use a base material having excellent water resistance.

Next, a specific method for solving the problems when the heat-sensitive adhesive sheet described above is wound up in a roll and stored, that is, blocking and a decrease in ink adhesion, will be described.

The present inventors have first studied which components in the heat-sensitive adhesive affect the above-mentioned problems, and have found the following facts. That is, the glass transition point and the molecular weight of the thermoplastic resin component, which is the base resin, particularly affect the blocking, and the lower the glass transition point, the lower the molecular weight, the lower the blocking tends to be. It becomes remarkable when stored in a high temperature environment. In addition, the wax component affects the decrease in ink adhesion,
The lower the melting point or softening point of the wax component, the lower the ink adhesion tends to be. Further, the degree of the problem also differs depending on the amounts of the respective components of the thermoplastic resin and the wax.

However, as a result of various studies on the types and amounts of the thermoplastic resin and the wax component, if the blocking or the ink adhesion, which is a problem, is improved, the intended adhesiveness is reduced, and good quality balance is not achieved. It turned out to be difficult.

For this reason, the present inventors have repeated studies on the surface properties of the heat-sensitive adhesive layer and the winding hardness of the roll-shaped winding, which are involved in the production of the heat-sensitive adhesive sheet. We found appropriate conditions. That is, the roll hardness of the roll-shaped heat-sensitive adhesive sheet is determined by the Schmid hammer method (J.T.
APPI paper pulp test method no. The roll is excellent in storability and adhesion without blocking or ink adhesion reduction by winding so that the average value of the degree of resilience (based on 37-81) is in the range of 10 to 40, preferably 15 to 30. It becomes a thermo-sensitive adhesive sheet.

If the average value of the degree of rebound according to the Schmidt hammer method is less than 10, winding deviation occurs, causing problems such as handleability and meandering during printing. Conversely, the same number is 4
If it exceeds 0, blocking and a decrease in ink adhesion may occur. Even if blocking can be prevented by using a blocking inhibitor such as a filler, it is impossible to suppress ink adhesion.

There is no particular limitation on the method of finishing the roll-shaped heat-sensitive adhesive sheet so that the average value of the rebound of the Schmidt hammer method is 10 to 40, and the heat-sensitive adhesive is applied to the substrate by the coating apparatus described above. Is achieved by tension control of a winder of the coating machine. In this case, the variation (profile) of the coating amount of the heat-sensitive adhesive affects the partial hardness of the winding, so that the variation is preferably small. Specifically, it is preferable to select a coating apparatus that can control the fluctuation width to a range of 10% or less with respect to a predetermined coating amount.

As the roll-shaped heat-sensitive adhesive sheet, when the heat-sensitive adhesive layer is applied and stored during a slitting step, a printing step, and the like, for example, a roll of about 2000 to 5000 m (a so-called raw fabric) is used. Or, after the slitting process, until it is applied to a printing machine or a printer, for example, 200 to 1000
There are windings of about m (so-called small windings) and the like. In any case, the average value of the degree of resilience of the surface by the Schmid hammer method needs to be 10 to 40. If the average value of the values on the surface is 10 to 40, the same degree of resilience is obtained inside the winding, and no quality problem occurs. As the core, a paper-made paper tube, a plastic-made paper tube, a metal-made paper tube, or the like can be used as appropriate.

Further, it is a more preferred embodiment that the smoothness of the surface of the heat-sensitive adhesive layer (J. TAPPI paper pulp test method No. 5: Oken type smoothness) is 100 to 1000 seconds. By the way, if the smoothness is less than 100 seconds, it is possible to almost completely avoid blocking and a decrease in ink adhesion, but care must be taken in application since there is a fear that adhesion may decrease. On the other hand, if the smoothness exceeds 1000 seconds, it becomes difficult to prevent blocking and decrease in ink adhesion.

The method for adjusting the smoothness of the surface of the heat-sensitive adhesive layer is not particularly limited. For example, a roll coater using a gravure roll, a pattern coating by a printing machine such as a gravure or screen, and a die coater described above. And the like. In addition, a method of producing a streaky coated surface by utilizing the hard fluidity of the heat-sensitive adhesive at the time of heat coating can be applied.

When the roll-shaped heat-sensitive adhesive sheet of the present invention is stored, when exposed to high humidity and high temperature,
It is preferable to store in a moisture-proof package at, for example, 40 ° C. or less, since blocking may occur. Also,
Since blocking easily occurs even by the weight of the sheet,
It is preferable to store, for example, a roll-shaped heat-sensitive adhesive sheet such that the core is perpendicular to the installation surface so that the weight is not easily applied.

When printing on the heat-sensitive adhesive sheet, a usual printing method can be used, but it is necessary to dry the sheet under a temperature condition at which the heat-sensitive adhesive layer does not melt. For example, drying at 70 ° C. or less is preferable. As a printing method, it is preferable to employ a method of curing a UV curable ink or an EB curable ink by UV irradiation or EB irradiation.

[0030]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but it is needless to say that the present invention is not limited thereto. In the examples, parts and% indicate "parts by weight" and "% by weight" unless otherwise specified.

Example 1 <Preparation of heat-sensitive adhesive sheet coated raw material> One side of printing paper (trade name "OK Top Coat", manufactured by Oji Paper Co., Ltd.) having a width of 750 mm and a rice area of 79.1 g / m ^2. , EVA (VA
c 28%) 40 parts, rosin ester (softening point 85 ° C) 3
A pan-feed type roll coater (a gravure roll having 150 lines was applied to an applicator roll while heating a thermosensitive adhesive having a solid content of 100% comprising 5 parts and 25 parts of paraffin wax (melting point 65 ° C.) to a temperature of 150 ° C.). Using), a coating width of 740 mm and a coating amount of 10 g / m ² were applied to obtain a roll-shaped heat-sensitive adhesive sheet raw material having a flow direction of 5000 m. At this time, a paper core (12 mm thick, 3 inches in inner diameter) was used as the core, the winding tension of the coater was set at 25 kg / cm, and the obtained roll-shaped heat-sensitive adhesive sheet had a winding hardness of: The resilience (hereinafter, Schmitt hammer value) of the Schmidt hammer method using a Schmidt hammer (“LR type”, manufactured by Fuji Bussan Co., Ltd.) was measured at 50 mm intervals in the width direction.
３２32 (average 25). The surface of the obtained heat-sensitive adhesive layer had an Oken-type smoothness of 500 seconds.

<Preparation of Small Winding for Printing> The heat-sensitive adhesive sheet was slit with a paper core (7 m) as a core.
m thickness, inner diameter 3 inches), take-up tension is 25 kg / cm, width 200 mm, length 1
Finished in small winding of 000 m. The Schmid hammer value of the small roll for printing was 20 to 30 (average 25) as a result of measuring the width direction at intervals of 50 mm.

Example 2 A plain roll was used for an applicator roll, and a winding tension with a slitter was 15 kg / c.
A small reel for printing was produced in the same manner as in Example 1 except that the conditions were set at m. The surface of the obtained heat-sensitive adhesive layer had an Oken-type smoothness of 10,000 seconds. The Schmid hammer value of the small roll for printing was 10 to 15 (average 12) as a result of measuring the width direction at intervals of 50 mm.

Example 3 A small winding for printing was performed in the same manner as in Example 1 except that a gravure roll having 100 lines was used as an applicator roll, and the winding tension with a slitter was performed under the condition of 30 kg / cm. Was prepared. The Oken type smoothness of the surface of the obtained heat-sensitive adhesive layer was 7 seconds. The Schmid hammer value of the small roll for printing was 31 to 40 (average 35) as a result of measuring the width direction at intervals of 50 mm.

Comparative Example 1 A small winding for printing was produced in the same manner as in Example 1 except that the winding tension of the slitter was 10 kg / cm. The Schmid hammer value of the small roll for printing was 7 to 11 (average: 9) as a result of measuring the width direction at intervals of 50 mm.

Comparative Example 2 A small printing roll was produced in the same manner as in Example 3 except that the winding tension with a slitter was performed at 35 kg / cm. The Schmid hammer value of the small roll for printing was 36 to 45 (average 42) as a result of measuring the width direction at intervals of 50 mm.

"Evaluation" The following evaluation was carried out on the small roll for printing of the obtained heat-sensitive adhesive sheet, and the results are shown in Table 1.

[Blocking] The treatment was carried out at 40 ° C. for 4 weeks and evaluated under the following conditions. ：: No blocking at all, very good. Δ: Slight blocking, but no practical problem. X: There is a practical problem due to blocking.

[Ink Adhesion] Stored at 40 ° C. for 4 weeks, printed with UV ink (trade name: No. 5L carton, manufactured by Tokasha Co., Ltd.), and evaluated according to the following conditions when cellotape was attached and peeled off. did. ：: The ink is not peeled at all and is excellent. Δ: The ink picked up a little, but there was no practical problem. ×: There is a practical problem because the ink is picked.

[Rolling deviation] During printing, the evaluation was made under the following conditions. ：: No winding deviation. Δ: Although slight winding deviation occurs, there is no meandering on the printing press, and there is no practical problem. X: The meandering on the printing press is severe due to the winding deviation, and there is a practical problem.

[Adhesive quality] The obtained heat-sensitive adhesive sheet was cut into labels of 5 cm x 10 cm, and the hot plate temperature was 120 ° C.
For 1 second to adhere to the glass bottle. Thereafter, the label was peeled off by hand, and the adhesive quality was evaluated based on the following conditions. ：: Extremely strong adhesion, making it difficult to peel off the label. Δ: Strongly adhered, the substrate was broken when the label was peeled off. X: The adhesion is weak and the label can be easily peeled off.

[Comprehensive Judgment] A: Excellent. ：: Excellent ×: Poor

[0043]

[Table 1]

[0044]

As is clear from the results in Table 1, the roll-shaped heat-sensitive adhesive sheet of the present invention basically does not affect the adhesive quality, has no blocking, and has excellent ink adhesion.
In addition, it is hard to cause winding deviation and is good.

Claims (2)

[Claims] 1. A rolled heat-sensitive adhesive sheet provided with a wax-containing heat-sensitive adhesive layer on one surface of a surface substrate, and the roll-shaped heat-sensitive adhesive sheet has a winding hardness determined by a Schmid hammer method ( J. TAPPI paper pulp test method N
o. 37-81), wherein the average value of the degree of resilience is from 10 to 40. 2. The smoothness of the surface of the heat-sensitive adhesive layer (J. TA).
PPI paper pulp test method No. 5) is 100 to 1000
The heat-sensitive adhesive sheet according to claim 1, wherein the time is seconds.