JP2001098226A - Uv-curable pressure-sensitive adhesive and pressure- sensitive adhesive sheet using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a UV-curable pressure-sensitive adhesive that gives a cured product which does not exhibit adhesiveness in an ordinary state but adheres to another cured product under a specified applied pressure and can be easily peeled therefrom irrespectively of the angle of peeling and to provide a pressure-sensitive adhesive sheet using the adhesive. SOLUTION: This UV-curable pressure-sensitive adhesive contains an acrylic oligomer, a photopolymerizable acrylic monomer, and a photopolymerization initiator. The photopolymerizable acrylic monomer that develops an elongation of at least 100% when measured under specified conditions is used for this purpose. Also, a pressure-sensitive adhesive sheet prepared by forming a layer of a cured product of the above adhesive on a specified part of the superposed surface of each substrate is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a UV-curable pressure-sensitive adhesive and a pressure-sensitive adhesive sheet using the same, and more particularly, to an information-carrying surface formed by folding or cutting a sheet. It has not been used in this type of printing sheet, such as a confidential information transmission sheet such as a folding sheet or a superimposed sheet, an arrangable sheet that can be expanded in size, and an office sheet such as copy paper. The present invention relates to a special UV-curable pressure-sensitive adhesive and a pressure-sensitive adhesive sheet for bonding the superposed surfaces with the UV-curable pressure-sensitive adhesive.

[0002]

2. Description of the Related Art Conventionally, in a printing sheet that carries information on a superimposed surface, the superposed surfaces are usually arranged in a pattern such that the superimposed surfaces are in contact with each other so as to adhere to each other. A cured layer of the pressure-sensitive adhesive is provided on the entire surface, partially or linearly. This pressure-sensitive adhesive is also referred to as a self-adhesive pressure-sensitive adhesive. When a high pressure is applied in a state where the cured layers are in contact with each other, the respective polymers adhere to each other by self-diffusion. Depending on the type of object and the degree of pressure, permanent adhesiveness and removable adhesiveness are realized.

Conventionally, the main component of the pressure-sensitive adhesive used in this type of printing sheet generally contains an aqueous medium such as an aqueous emulsion such as an acrylic emulsion, a natural rubber latex, or a synthetic rubber latex, or a rubber latex. When a pressure-sensitive adhesive containing such an aqueous medium is applied to the surface of a substrate such as paper and dried for the formation of a cured layer, a special dryer is required or the working time is increased. In addition, it has disadvantages such as deformation of a base material such as paper and loss of information carried.

[0004]

In order to solve the problems of the conventional pressure-sensitive adhesives, the present inventors have proposed a solventless UV-curable pressure-sensitive adhesive which does not use an aqueous medium (Japanese Patent Application Laid-Open No. 10-1998). 263466, JP-A-10-26
No. 5742). However, when this UV-curable pressure-sensitive adhesive is adhered by applying a high pressure in a state where the cured layers are in contact with each other, it is easy to peel in the 90 ° direction after the adhesion, but it is easy to peel in the 180 ° direction. However, there is a problem in that if the adhered members are shifted in parallel such that they are separated from each other, they are not easily separated, and if they are forcibly separated, the substrate may be broken.

A first object of the present invention is to provide a UV-curable pressure-sensitive type which can be easily peeled regardless of the angle at which the cured layers are adhered to each other by applying high pressure in a state where the cured layers are in contact with each other. A second object of the present invention is to provide an adhesive,
A pressure-sensitive adhesive sheet in which a cured layer is formed at a predetermined position on a superposed surface of a substrate using such a UV-curable pressure-sensitive adhesive, and high pressure is applied while the cured layers are in contact with each other. It is an object of the present invention to provide a pressure-sensitive adhesive sheet which can be easily peeled regardless of a peeling direction after being adhered and adhered.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to solve the above-mentioned problems, and as a result, a UV-curable pressure-sensitive adhesive containing an acrylic photopolymerizable monomer having a specific elongation has been developed. It has been found that by using such a cured layer, the cured layers can be easily peeled irrespective of the angle at the time of peeling, after being adhered by applying a high pressure in a state where the cured layers are in contact with each other, and the present invention has been completed.

A first object of the present invention is to provide an acrylic oligomer which does not adhere in a normal state after curing but adheres to each other by applying a predetermined pressure to each other, but which can be easily peeled off if necessary. And a UV curable pressure-sensitive adhesive containing an acrylic photopolymerizable monomer and a photopolymerization initiator,
The present invention relates to a UV-curable pressure-sensitive adhesive, characterized in that the acrylic photopolymerizable monomer contains an acrylic photopolymerizable monomer having an elongation of 100% or more measured under the following measurement conditions. (Measurement conditions) (1) A solution is prepared by mixing an acrylic photopolymerizable monomer and a photopolymerization initiator at a ratio of 100: 1 (weight ratio). (2) This solution is irradiated with UV light twice a front and back twice for 3 minutes using a UV lamp (60 W / cm, lamp height 30 cm) to produce a UV cured product. (3) This UV-cured product was subjected to a temperature of 23 ± 2 ° C. and a relative humidity of 50.
Condition at + 5% for at least 48 hours. (4) Punch out the conditioned UV cured product using a dumbbell No. 2 mold to prepare a measurement sample. (5) Plastic tensile test method (JISK630)
According to 1), using a Tensilon type tensile test, the measurement sample is pulled at a tension speed of 10 mm / min, and the elongation (%) is determined from the length between the marked lines at the time of cutting.

[0008] The UV-curable pressure-sensitive adhesive of the present invention can be obtained by irradiating ultraviolet rays from a suitable ultraviolet light source such as a high-pressure mercury lamp or a metal halide lamp under appropriate conditions. The system-based photopolymerizable monomer itself is polymerized and cured, and the acrylic oligomer and the acrylic-based photopolymerizable monomer are copolymerized, whereby the entire adhesive is appropriately cured. The UV-curable pressure-sensitive adhesive of the present invention contains, as an acrylic photopolymerizable monomer, an acrylic photopolymerizable monomer having an elongation percentage of 100% or more measured under the above-described measurement conditions. The flexibility of the cured product is improved, and after being adhered, the cured product can be easily peeled regardless of the angle at which it is peeled.

According to a second aspect of the present invention, there is provided a UV light source according to the first aspect.
In the curable pressure-sensitive adhesive, 10 to 40 parts by weight of an acrylic photopolymerizable monomer having an elongation of 100% or more is blended in 100 parts by weight of a mixture of an acrylic oligomer and an acrylic photopolymerizable monomer. It is characterized by the following.

According to a third aspect of the present invention, there is provided a laminating sheet to which a superposed surface is releasably adhered, wherein a UV light according to the first or second aspect is provided on a predetermined portion of the superposed surface of the substrate. The present invention relates to a pressure-sensitive adhesive sheet provided with a cured layer of a curable pressure-sensitive adhesive. The pressure-sensitive adhesive sheet of the present invention, in which a cured layer of the UV-curable pressure-sensitive adhesive of the present invention is provided on a predetermined portion of the superposed surface of the base material, applies high pressure while the cured layers are in contact with each other. After being adhered by being applied, it can be easily peeled regardless of the angle at the time of peeling.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The acrylic oligomer used in the present invention is an oligomer having an acryloyl group or a methacryloyl group at an end. Examples of such an oligomer include an epoxy acrylate, a polyester acrylate, a polyvinyl alcohol-based oligomer, a polyacrylic acid-based oligomer, and a urethane-based oligomer. And acrylates of epoxy resins, for example, diglycidyl ether diacrylate of bisphenol A, reaction products of epoxy resin with acrylic acid and methyltetrahydrophthalic anhydride, Epoxy acrylates such as reaction products with -hydroxyethyl acrylate,

Ring-opening copolymers of glycidyl diacrylate and phthalic anhydride, esters of methacrylic acid dimer and polyol, polyesters obtained from acrylic acid, phthalic anhydride and propylene oxide, polyethylene glycol and maleic anhydride Polyester-based oligomers such as reaction products with glycidyl methacrylate,

A reaction product of polyvinyl alcohol and N-methylolacrylamide, a polyvinyl alcohol oligomer such as one obtained by esterifying polyvinyl alcohol with succinic anhydride and then adding glycidyl methacrylate, methyl vinyl ether-maleic anhydride Polyacrylic acid-based oligomers such as a reaction product of a copolymer and 2-hydroxyethyl acrylate or a product obtained by further reacting glycidyl methacrylate;

A urethane oligomer having a polyoxyalkylene segment and / or a saturated polyester segment linked via a urethane bond and having an acryloyl group or a methacryloyl group at both ends can be mentioned. These may be used alone or in combination of two or more. Further, it can be used in combination with an oligomer other than the acrylic oligomer.

Of these, epoxy-based acrylates, polyester-based acrylates, urethane-based acrylates, and oligomers combining two or more of these can be preferably used in the present invention. Further, it has a bifunctional or more preferably bifunctional functional group, does not have a side chain structure of an alkyl group or an alkylphenyl group of ethyl group or more in the main chain, and has a glass transition point of 0 ° C. or more of 60 ° C. or more of the cured film. Aliphatic epoxy acrylate, polyester acrylate, urethane acrylate (e.g., for example, Kurodamer UVU-300, UVU-310, UVE-150, manufactured by Nippon Crowda Co., Ltd.)
And the like, and an oligomer obtained by combining two or more of these can be more preferably used.

These acrylic oligomers preferably have a weight average molecular weight in the range of 2,000 to 30,000. If a material having a lower molecular weight is used, the handling becomes difficult due to high tackiness and blocking occurs, and if a material having a higher molecular weight is used, the pressure-sensitive adhesive property after curing is reduced, so that It cannot be used for releasable bonding.

The amount of the acrylic oligomer is about 1 part by weight to 50 parts by weight based on the whole pressure-sensitive adhesive (acrylic oligomer + acrylic photopolymerizable monomer = 100 parts by weight).
It is suitable that the amount is 5 parts by weight, preferably 5 parts by weight to 50 parts by weight, more preferably 10 parts by weight to 50 parts by weight, particularly preferably 20 parts by weight to 50 parts by weight. If the amount of the acrylic oligomer is less than 1 part by weight, the flexibility may not be improved, and if it exceeds 50 parts by weight, the pressure-sensitive adhesive property after curing may be reduced.

Next, specific examples of the acrylic photopolymerizable monomer used in combination with the acrylic oligomer in the present invention include unsaturated carboxylic acids such as acrylic acid and methacrylic acid and esters thereof, for example, alkyl- , Cycloalkyl-, halogenated alkyl-, alkoxyalkyl-, hydroxyalkyl-, aminoalkyl-, tetrahydrofurfuryl-, allyl-, glycidyl-, benzyl-, phenoxy-acrylate and methacrylate,

Lower alkylene glycol, acrylamide, methacrylamide or derivatives thereof, for example, acrylamide and methacrylamide mono- or di-substituted with an alkyl group or hydroxyalkyl group, diacetone acrylamide and methacrylamide, N, N'-alkylenebisacrylamide And methacrylamide.

These may be used alone or in combination of two or more. However, the UV of the present invention
It is important that the curable pressure-sensitive adhesive contains, as an acrylic photopolymerizable monomer, an acrylic photopolymerizable monomer having an elongation of 100% or more measured under the above measurement conditions.
In the present invention, it is preferable to use a mixture of an acrylic photopolymerizable monomer having an elongation of 100% or more and an acrylic photopolymerizable monomer having an elongation of less than 100%.

Specific examples of the acrylic photopolymerizable monomer having an elongation of 100% or more include the following acrylic photopolymerizable monomers. Paramylphenol EO-modified (n @ 1) acrylate (manufactured by Toagosei Co., Ltd., Aronix M-110, viscosity 110-2)
In the case of 10 cps (25 ° C., Tg 35 ° C.), the elongation is 300%. Nonylphenol EO modification (n ≒ 1)
Acrylate (Toa Gosei Co., Aronix M-11
1. In the case of a viscosity of 60 to 90 cps (25 ° C., Tg of 17 ° C.), the elongation is 250%. Trimethylolpropane PO-modified (n @ 1) triacrylate (manufactured by Toagosei Co., Ltd., Aronix M-310, viscosity: 60 to 110 cps)
(25 ° C.) and Tg of 120 ° C.), the elongation percentage is 120%.
It is. Urethane acrylate (manufactured by Toagosei Co., Ltd., Aronix M-1310, bifunctional, viscosity 50,6000-8)
7,000 cps (50 ° C), Tg-25 ° C)
The elongation is 125%.

In the present invention, 100 to 100 parts by weight of a mixture of an acrylic oligomer and an acrylic photopolymerizable monomer contains 10 to 40 parts by weight, preferably 15 to 40 parts by weight of an acrylic photopolymerizable monomer having an elongation of 100% or more. Desirably, 35 parts by weight is contained. If the acrylic photopolymerizable monomer having an elongation of 100% or more is less than 10 parts by weight, the acrylic polymerizable monomer may not be peeled off depending on the angle at which it is peeled.
No further effect can be expected even if it exceeds 0 parts by weight.

As the photopolymerization initiator used together with the acrylic oligomer and the acrylic photopolymerizable monomer, any one of known photopolymerization initiators can be selected and used. Specific examples of such a photopolymerization initiator include, for example, benzoin alkyl ethers such as benzoin, benzoin ethyl ether, benzoin-n-propyl ether, benzoin-isopropyl ether, and benzoin isobutyl-ether, and 2,2-dimethoxy. -Phenyl-2-acetophenone, benzophenone, benzyl, diacetyl, diphenyl sulfide, eosin, thionine, 9,10-anthraquinone, 2-ethyl-9,10-anthraquinone and the like.

These photopolymerization initiators may be used alone or in combination of two or more. The compounding amount is about 0.1% by weight to 10% by weight based on the entire pressure-sensitive adhesive (acrylic oligomer + acrylic photopolymerizable monomer + photopolymerization initiator = 100% by weight).
Is selected in the range.

The UV-curable pressure-sensitive adhesive of the present invention includes the acrylic oligomer, the acrylic photopolymerizable monomer,
In addition to the three components of the photopolymerization initiator, if necessary, additional components commonly used in general photosensitive resin compositions such as a thermal polymerization inhibitor, a tackifier, a viscosity modifier, an antioxidant, and a stabilizer. Agents, coloring agents, fine particle fillers, and the like.

Examples of the thermal polymerization inhibitor include hydroquinone, mono-tert-butylhydroquinone, benzoquinone,
2,5-diphenyl-p-benzoquinone, picric acid,
Examples thereof include di-p-fluorophenylamine, di-p-methoxyphenol, and 2,6-ditert-butyl-p-cresol. These thermal polymerization inhibitors are for preventing a thermal polymerization reaction, and therefore, the content of the thermal polymerization inhibitor is usually set to 100% by the UV-curable pressure-sensitive adhesive.
It is selected in the range of 0.01 to 5 parts by weight per part by weight.

The pressure-sensitive adhesive sheet of the present invention can be produced, for example, as follows. That is, according to the present invention, a predetermined base material sheet is applied to a portion opposed to each other by folding, tri-folding, cutting and overlapping, or overlapping of separate bodies by a coating means such as a gravure coater, a flexo, an air knife coater, and a bar coater. UV-curable pressure-sensitive adhesive is applied and then dried to form an adhesive layer. The application at this time may be performed over the entire surface of the substrate sheet, or may be performed only on a part of the surface. Necessary information may be printed on the surface of the base sheet in advance, or the information may be printed after applying an adhesive layer. At this time, when printing information with a commonly used printing machine using ultraviolet curable ink for printing, this printing process and the U
This is advantageous because it can be performed simultaneously with the application and fixing of the V-curable pressure-sensitive adhesive.

The base material used in the present invention includes, for example, high quality paper, medium paper, rough paper, and cotton paper which are uncoated papers; art paper, coated paper, lightweight coated paper which is coated paper, and the like. , Plastic laminated paper, cloth, plastic laminated cloth, plastic film, metal foil and the like. The basis weight of the substrate is usually 50 to 160 g / m
^{About 2} . In the present invention, as a substrate, polyethylene, polypropylene, polyethylene terephthalate,
When a synthetic plastic film such as polyvinyl chloride is used, it is preferable to apply a surface treatment such as a mat treatment or a corona treatment to the surface of the substrate.

The amount of the UV-curable pressure-sensitive adhesive of the present invention applied to the surface of the substrate is 1 to 30 g / m ² for maintaining the adhesiveness, peelability or transparency of the adhesive layer. Preferably 3 to 20 g / m ² , more preferably 5 to 15 g / m ^2
It is chosen to be in the range of ² .

The pressure-sensitive adhesive sheet manufactured in this manner is irradiated with ultraviolet rays to cure the adhesive layer appropriately, and then the cured adhesive layers on the respective surfaces are overlapped. Under a pressure of about 1 to 100 kg / cm ² .

The permanent adhesion and the removability of the cured layer of the UV-curable pressure-sensitive adhesive of the present invention are determined by the types of the acrylic oligomer and the acrylic photopolymerizable monomer,
It can be adjusted by changing the number of functional groups of the acrylic photopolymerizable monomer, the roller pressure at the time of bonding, and the like.
In general, as the number of functional groups of the acrylic photopolymerizable monomer increases, the bonding surface becomes harder and the bonding force decreases, and as the roller pressure during bonding increases, the bonding force increases.

In the pressure-sensitive adhesive sheet of the present invention, U
It is preferable that the information on the cured layer of the V-curable pressure-sensitive adhesive is printed with an acrylic ultraviolet curable ink or an acrylic resin toner.

First, the acrylic UV curable ink is usually a vehicle composed of an acrylic oligomer, an acrylic photopolymerizable monomer, and a photopolymerization initiator, and a coloring agent, for example, a black pigment or carbon black, a dispersant, and a stabilizer. It is adjusted by blending a matting agent, a fungicide, a viscosity modifier and the like. The acrylic oligomer, the acrylic photopolymerizable monomer and the photopolymerization initiator in this case are exemplified as the acrylic oligomer, the acrylic photopolymerizable monomer and the photopolymerization initiator in the UV-curable pressure-sensitive adhesive. Can be selected and used. In addition, when this ink is used, the application and fixing process of the UV-curable pressure-sensitive adhesive and printing and
The drying step can be performed simultaneously.

When printing information on a cured layer of a UV-curable pressure-sensitive adhesive using a toner such as a laser printer or a digital press, an acrylic resin toner is most preferable. Currently, commonly used toners include, in addition to acrylic resins, which are currently the mainstream, epoxy resins, polystyrene resins, polyester resins, and polypropylene resins as main components. Each of the toners adheres to the cured layer of the UV-curable pressure-sensitive adhesive of the present invention, but, like the acrylic UV-curable ink, the toner is formed of an acrylic resin similar to the cured layer, thereby obtaining the toner. The adhesiveness between the layer and the cured layer is enhanced, and information can be provided very well.

In the present invention, it is advantageous that the UV-curable pressure-sensitive adhesive and the UV-curable ink have compositions as similar as possible. In this case, the adhesion between the two is improved, and the characters and patterns are not blurred or peeled off.

Next, examples of the structure of the pressure-sensitive adhesive sheet of the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited to these examples. FIG.
1 is a plan view of a two-fold pressure-sensitive adhesive sheet as a first configuration example of the present invention, FIG. 2 is a cross-sectional view taken along line XX of FIG. 1, and FIG.
FIG. 4 is a plan view of a three-fold pressure-sensitive adhesive sheet according to a second embodiment of the present invention, and FIG. 5 is a back view of the pressure-sensitive adhesive sheet of FIG. FIG. 6
FIG. 7 is an explanatory view of a state of superposition of the pressure-sensitive adhesive sheet of FIG. 4, and FIG. 7 is an explanatory view of various means for facilitating separation of the superposed surface after bonding.

The first embodiment of the present invention shown in FIGS. 1 to 3 is a superimposed surface 3 constructed as a "concealment postcard".
This is a two-fold pressure-sensitive adhesive sheet 1 in which a cured layer 4 of a UV-curable pressure-sensitive adhesive is applied to the entire surface. This is because the upper sheet A and the lower sheet C are folded by the folding perforation line Mf.
And concealed information in a state of being folded in two as shown in FIG. As shown in FIGS. 1 and 3, a general print 5 such as a postal code entry field, a purchase information entry field, a company name, etc. is provided on the front and back surfaces of the base sheet 2, and is also overlapped when folded. The entire surface of the mating surface 3, that is, the entire surface of one side of the upper sheet A and the lower sheet C
A cured layer 4 of a curable pressure sensitive adhesive is provided.

In this embodiment, cuts K are provided at the corners of the upper sheet A to form a partial step between the upper sheet A and the lower sheet B, thereby facilitating separation of the superposed surface after bonding. And As such peeling facilitating means, as shown in FIG. 7, (a) a step is provided by making a cut K at the corner of the overlapping surface as in this configuration example, or (b) Make a notch K on the side to create a step,
(C) A method of extending the flap piece F on one of the overlapping surfaces to provide a step can be adopted.

A second embodiment of the present invention shown in FIGS. 4 to 6 is a superimposed surface 3 constructed as a "concealment postcard".
This is a three-fold pressure-sensitive adhesive sheet 1 in which a cured layer 4 of a UV-curable pressure-sensitive adhesive is applied to the entire surface. This is because the base sheet 2 is divided into an upper sheet piece A, a middle sheet piece B, and a lower sheet piece C by two folding perforation lines Mf, Mf, and as shown in FIG. It carries concealment information in a folded state. Then, as shown in FIGS. 4 and 5, on the front and back surfaces of the base sheet 2, a general print 5 such as a postal code entry field, a variable information entry field, an explanatory note, etc. is given, and the base sheet 2 is folded into a Z-shape. A cured layer 4 of a UV-curable pressure-sensitive adhesive is applied to the entire surface of the overlapping surface 3 in this case.

[0040]

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to these Examples without departing from the gist of the present invention. (Example 1) As an acrylic photopolymerizable monomer having an elongation of less than 100%, trifunctional acrylate (manufactured by Toagosei Co., Ltd., M310, modified with trimethylolpropane PO (n ≒)
1) Triacrylate, viscosity 60 to 110 cps / 25
50 ° C., Tg 120 ° C., elongation 0 to 5%) 50 parts by weight, monofunctional acrylate (manufactured by Toagosei Co., Ltd., M113, nonylphenol EO-modified (n ≒ 4) acrylate, viscosity 80 to 1)
10 cps / 25 ° C, Tg-20 ° C, elongation rate 50%) 1
5 parts by weight, bifunctional acrylate (M22, manufactured by Toagosei Co., Ltd.)
5. Polypropylene glycol diacrylate (n ≒)
7), viscosity 30-50 cps / 25 ° C., Tg-8 ° C., elongation 10%) 15 parts by weight,

As an acrylic photopolymerizable monomer having an elongation of 100% or more, a monofunctional acrylate (M110 manufactured by Toagosei Co., Ltd., modified with paracumylphenol EO (n ≒)
1) Acrylate, viscosity 110-210 cps / 25
10 ° C., Tg 35 ° C., elongation 300%), 10 parts by weight of an urethane acrylate (manufactured by Nippon Crowda Co., Ltd., Kurodamer UVU310) as an acrylic oligomer,
The UV-curable pressure-sensitive composition of the present invention containing 10 parts by weight of an epoxy acrylate (manufactured by Nippon Crowda Co., Kurodamer UVE150) and 8 parts by weight of Irgacure 907 manufactured by Ciba Specialty Chemicals, Inc. as a photopolymerization initiator. An adhesive was prepared. The UV-curable pressure-sensitive adhesive thus obtained was applied to a coated paper having a continuous weight of 110 kg at a rate of 10 g / cm ^{2 using} a wire bar, and then subjected to an exposure treatment using an ultraviolet irradiation device manufactured by iGraph Fix Co., Ltd. And cured. Thus, the pressure-sensitive adhesive sheet of the present invention having a colorless, transparent and glossy cured layer was produced.
Next, on the day of production, the 90 ° peel (T-peel) adhesive force (A) and the 180 ° peel adhesive force (B) of the pressure-sensitive adhesive sheet were evaluated by the following methods. The results are shown in Table 1.

Measurement method of 90 ° peeling (T-type peeling) adhesive strength (A) and 180 ° peeling adhesive strength (B): The obtained pressure-sensitive adhesive sheet was cut into 25 mm width and 100 mm length samples. The two samples were superposed on each other with a length of 25 mm and pressed under a load of 100 kg / cm ² , and then subjected to an autograph AGS50 (manufactured by Shimadzu Corporation) in accordance with JIS K 6854, an adhesive peeling strength test method. 90 ° peeling (T-peeling) adhesive force using (gf / 25 mm)
(A) and 180 ° peel adhesion (gf / 25 mm)
(B) is measured.

(Examples 2-3) The elongation percentage shown in Table 1 was 1
Acrylic photopolymerizable monomer of less than 00%, elongation percentage is 1
The UV-curable pressure-sensitive adhesive of the present invention was prepared in the same manner as in Example 1 except that at least 00% of an acrylic photopolymerizable monomer, an acrylic oligomer, and a photopolymerization initiator were used in the composition shown in Table 1. A pressure-sensitive adhesive sheet of the present invention was produced. Then, in the same manner as in Example 1, the pressure-sensitive adhesive sheet 9
The 0 ° peeling (T-type peeling) adhesive strength and the 180 ° peeling adhesive strength were evaluated, and the results are shown in Table 1.

Examples 4 to 6 Monofunctional acrylate (M110, paracumylphenol E, manufactured by Toa Gosei Co., Ltd.) as an acrylic photopolymerizable monomer having an elongation of 100% or more.
O-modified (n ≒ 1) acrylate, viscosity 110-210c
ps / 25 ° C., Tg 35 ° C., elongation 300%) instead of urethane acrylate (M131, manufactured by Toagosei Co., Ltd.)
0, viscosity 56,000-87,000 cps / 25 ° C,
(Tg-25 ° C., elongation: 125%) and the same procedure as in Examples 1 to 3 except that the components shown in Table 1 were used. A pressure-adhesive sheet was produced. Then, in the same manner as in Example 1, 90 ° peeling (T-peeling) adhesive force of the pressure-sensitive adhesive sheet and 18
The 0 ° peel adhesion was evaluated, and the results are shown in Table 1.

Comparative Example 1 Example 1 was repeated except that an acrylic photopolymerizable monomer having an elongation of 100% or more was not used.
A UV-curable pressure-sensitive adhesive and a pressure-sensitive adhesive sheet for comparison were produced in the same manner as in the above. Next, the 90 ° peeling (T-type peeling) adhesive force and the 180 ° peeling adhesive force of the pressure-sensitive adhesive sheet were evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[0046]

[Table 1]

From Table 1, it can be seen that the pressure-sensitive adhesive sheets of the present invention using the UV-curable pressure-sensitive adhesives of the present invention of Examples 1 to 6 are as follows:
90 ° peeling (T-type peeling) Adhesive strength (A) is moderate,
180 ° peel adhesion (B) is not high, (B) / (A)
Since the ratio is low, it can be seen that the film can be easily peeled regardless of the angle at which the film is peeled after being adhered. In contrast, the elongation is 1
In the case of Comparative Example 1 in which no acrylic photopolymerizable monomer of 00% or more was used, the 90 ° peeling (T-type peeling) adhesive strength (A) was moderate, but the 180 ° peeling adhesive strength (B) was high. , (B) / (A) ratio is high, and peeling is not possible depending on the angle at the time of peeling.

[0048]

Since the UV-curable pressure-sensitive adhesive according to the first aspect of the present invention is a non-aqueous type, it does not cause wrinkles due to drying, and the cured layer has gloss and appearance. Is good, and printing can be performed thereon. Further, after the cured layers are brought into close contact with each other by applying strong pressure and adhered to each other, they can be easily peeled regardless of the angle at which they are peeled.

The UV-curable pressure-sensitive adhesive according to claim 2 of the present invention has an acrylic photopolymerization having an elongation of 100% or more in 100 parts by weight of a mixture of an acrylic oligomer and an acrylic photopolymerizable monomer. Since the cured monomer is contained in an amount of 10 to 40 parts by weight, the cured layers can be peeled more easily regardless of the angle at which the cured layers are adhered and adhered to each other by applying high pressure in a state where the cured layers are in contact with each other.

The pressure-sensitive adhesive sheet according to the third aspect of the present invention is a sheet having a cured layer of the UV-curable pressure-sensitive adhesive of the present invention provided on a predetermined portion of a superposed surface of a substrate. After the layers are brought into close contact with each other by applying a high pressure to make them adhere to each other, they can be easily peeled regardless of the angle at which they are peeled. The pressure-sensitive adhesive sheet of the present invention may be a folded sheet in which a surface superimposed by folding or cutting is used as an information carrying surface, a confidential information-transmitting sheet such as a superposed sheet, or a dimensionally expandable arrangement. It is useful as an office sheet such as a sheet or copy paper.

[Brief description of the drawings]

FIG. 1 is a plan view of a two-fold pressure-sensitive adhesive sheet that is a first configuration example of the present invention.

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is an explanatory view of a superposed state of the pressure-sensitive adhesive sheet of FIG. 1;

FIG. 4 is a plan view of a tri-fold pressure-sensitive adhesive sheet according to an example of the present invention.

FIG. 5 is a back view of the pressure-sensitive adhesive sheet of FIG.

FIG. 6 is an explanatory view of a superposed state of the pressure-sensitive adhesive sheet of FIG.

FIG. 7 is an explanatory view of various means for facilitating peeling of a superposed surface after bonding.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pressure-sensitive adhesive sheet 2 Base sheet 3 Lamination surface 4 Cured layer of UV-curable pressure-sensitive adhesive 5 General printing part A Upper paper piece B Middle paper piece C Lower paper piece Mc Cutting perforation line Mf Folding perforation line

Claims (3)

[Claims] 1. An acrylic oligomer and an acrylic photopolymerizable material which are not adhered in a normal state after curing, but are adhered to each other by applying a predetermined pressure to each other, but which can be easily peeled off as required. A UV-curable pressure-sensitive adhesive containing a monomer and a photopolymerization initiator, wherein the acrylic photopolymerizable monomer has an elongation of 100% or more measured under the following measurement conditions as the acrylic photopolymerizable monomer. A UV-curable pressure-sensitive adhesive, comprising: (Measurement conditions) (1) A solution is prepared by mixing an acrylic photopolymerizable monomer and a photopolymerization initiator at a ratio of 100: 1 (weight ratio). (2) This solution is irradiated with UV light twice a front and back twice for 3 minutes using a UV lamp (60 W / cm, lamp height 30 cm) to produce a UV cured product. (3) This UV-cured product was subjected to a temperature of 23 ± 2 ° C. and a relative humidity of 50.
Condition at + 5% for at least 48 hours. (4) Punch out the conditioned UV cured product using a dumbbell No. 2 mold to prepare a measurement sample. (5) Plastic tensile test method (JISK630)
According to 1), using a Tensilon type tensile test, the measurement sample is pulled at a tension speed of 10 mm / min, and the elongation (%) is determined from the length between the marked lines at the time of cutting. 2. An elongation rate of 10 in 100 parts by weight of a mixture of an acrylic oligomer and an acrylic photopolymerizable monomer.
0-4% or more of acrylic photopolymerizable monomer is 10-4
2. The UV-curable pressure-sensitive adhesive according to claim 1, wherein the UV-curable pressure-sensitive adhesive is contained in an amount of 0 part by weight. 3. A UV-curable pressure-sensitive adhesive according to claim 1 or 2, wherein said sheet is a laminating sheet to which said laminating surface is peelably bonded. Pressure-sensitive adhesive sheet provided with a cured layer.