JP2001139920A - Pressure-sensitive adhesive composition and pressure- sensitive adhesive sheet using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain both a pressure-sensitive adhesive composition having a sufficient adhesive strength not only in the initial bonding of mutual cured layers but also even when heated after bonding or heated at high temperatures in air after the bonding or being irradiated with ultraviolet rays and a pressure- sensitive adhesive sheet having good hiding properties and using the pressure- sensitive adhesive composition. SOLUTION: This pressure-sensitive adhesive composition used is prepared by compounding preferably 100 pts.mass of an unpeeling adhesive base with 5-40 pts.mass of a thermosetting resin, 5-20 pts.mass of a flame retardant, 0.5-5 pts.mass of an antioxidant and 0.1-1 pt.mass of an ultraviolet light absorber. The pressure-sensitive adhesive sheet has a coating layer of the pressure- sensitive adhesive composition in at least a part of a substrate sheet surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet having an adhesive layer formed by applying the same, and more particularly to heat resistance and air oxidation resistance. And a pressure-sensitive adhesive composition having an improved ultraviolet light resistance, and a pressure-sensitive adhesive sheet having a double-faced surface which is temporarily adhered, but can be easily peeled off when necessary, having an adhesive layer formed by applying the same. More particularly, the present invention relates to a pressure-sensitive adhesive sheet suitable as a confidential information sheet such as a folding card, an overlapping card, an information hiding sheet, or the like, a scalable arrangement sheet, a printing sheet, a copying sheet, or the like.

[0002]

2. Description of the Related Art In recent years, with the amendment of the Postal Law, postcard systems having confidentiality have been put to practical use and have begun to spread.
This postcard system having confidentiality is, for example, a postcard in which various information such as personal information or print information or print information is described is folded, a superposed portion is adhered, the information is hidden, and then mailed. In this system, the recipient reads the hidden information by peeling off the overlapped portion again.

[0003] Conventionally, as a pressure-sensitive adhesive sheet, for example, an adhesive consisting of a non-peelable adhesive base and a fine particle filler exhibiting no affinity for the adhesive base is provided on the superposed surface of the base sheet. (Japanese Patent Application Laid-Open No. 4-59395) and those having an adhesive layer formed on the surface of a base sheet in advance and having an adhesive layer formed on the surface of the base sheet have been proposed (Jpn. JP-A-147069, Japanese Patent Application No. 7-
188378). However, the conventional pressure-sensitive adhesive sheet is an adhesive base composed of only a natural rubber-based adhesive or an adhesive obtained by mixing a natural rubber-based adhesive with a synthetic rubber or a synthetic resin emulsion as a peelable adhesive. Since the adhesive composition composed of a base material or a fine particle filler exhibiting incompatibility with the adhesive base was used, the cured layers were brought into contact with each other and a predetermined pressure was applied and bonded. At first, it has good adhesive strength, so it has good concealment property, but if it is heated after bonding, heated to high temperature in the air after bonding, or irradiated with ultraviolet light before bonding, the bonding strength decreases There was a problem.

[0004]

SUMMARY OF THE INVENTION The first object of the present invention is not only to start with the cured layers being brought into contact with each other and to apply a predetermined pressure, but also to be heated after the bonding or in the air after the bonding. A second object of the present invention is to provide a pressure-sensitive adhesive composition having a sufficient adhesive strength even when heated to a high temperature or irradiated with ultraviolet rays. Is a pressure-sensitive adhesive sheet having a double-sided surface that temporarily adheres, but can easily be peeled off when necessary, and has a predetermined surface by making the cured layers contact each other. At the beginning of applying pressure and bonding, of course, it is heated after bonding, or heated to high temperature in air after bonding,
Alternatively, it is an object of the present invention to provide a pressure-sensitive adhesive sheet having a sufficient adhesive force even when irradiated with ultraviolet rays and having a good concealing property.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies on a pressure-sensitive adhesive composition for a pressure-sensitive adhesive sheet. As a result, a natural rubber-based pressure-sensitive adhesive, a synthetic rubber, and a synthetic resin emulsion were obtained. It has been found that by appropriately blending a thermosetting resin, a flame retardant, an antioxidant, and an ultraviolet absorber with a non-peelable adhesive base such as the above, the problem can be solved by the synergistic action of these components. The present invention has been accomplished.

That is, a first aspect of the present invention is a sense which is characterized in that a thermosetting resin, a flame retardant, an antioxidant, and an ultraviolet absorber are blended with a non-peelable adhesive base. It relates to a pressure-sensitive adhesive composition.

According to a second aspect of the present invention, in the pressure-sensitive adhesive composition according to the first aspect, 5 to 40 parts by weight of a thermosetting resin and 100 parts by weight of a non-peelable adhesive base, and a flame retardant are used. 5-
20 parts by mass, an antioxidant of 0.5 to 5 parts by mass, and an ultraviolet absorber of 0.1 to 1 part by mass.

[0008] Claim 3 of the present invention relates to a pressure-sensitive adhesive sheet having a coating layer of the pressure-sensitive adhesive composition according to claim 1 or 2 on at least a part of the surface of a base sheet.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The pressure-sensitive adhesive composition of the present invention has an opacity which forms an adhesive layer which does not adhere under normal conditions, adheres under pressure, and can be peeled off when necessary, that is, forms a so-called adhesive layer. Or a non-peelable adhesive base comprising a natural rubber-based pressure-sensitive adhesive base, a synthetic rubber, a synthetic resin emulsion or a mixture of two or more thereof, or a non-peelable base A thermosetting resin, a flame retardant, an antioxidant, and an ultraviolet ray are applied to the non-peelable adhesive base obtained by mixing a non-affinity filler having incompatibility with the non-adhesive base as needed. It is blended with an absorbent.

The base for a natural rubber-based pressure-sensitive adhesive used in the pressure-sensitive adhesive composition of the present invention can be arbitrarily selected from those conventionally used as a base for a natural rubber-based pressure-sensitive adhesive. it can. Examples of such a latex include a latex mainly composed of natural rubber, and a modified version of the latex, such as an acidic latex, a depolymerized latex, a vulcanized latex, or a grafted natural rubber latex. From the viewpoints of heat resistance, abrasion resistance and the like, a natural rubber latex obtained by graft copolymerizing styrene and methyl methacrylate on natural rubber is particularly preferred.

Synthetic rubber emulsions include synthetic rubber latex commonly used as a component of an adhesive,
For example, an emulsion in which a synthetic rubber such as polyisoprene rubber, polybutadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, methyl methacrylate-butadiene rubber, chloroprene rubber, butyl rubber, polyurethane rubber, thiochol rubber, and acrylic rubber is dispersed in an aqueous solvent. Used. At this time, an emulsifier is required to stabilize the dispersion of the latex particles. As the emulsifier, an anionic surfactant such as rosin soap, naphthalene sulfonate, fatty acid soap, or alkylbenzene sulfonate is generally used. Can be

As the synthetic resin emulsion, a polyvinyl acetate emulsion, a vinyl acetate-ethylene copolymer emulsion, a polyacrylate emulsion, a polyvinyl chloride emulsion and the like are used. In order to stabilize the dispersion of these synthetic resin emulsions, the same emulsifiers as those used in the synthetic rubber latex can be used.

The thermosetting resin used in the pressure-sensitive adhesive composition of the present invention is not particularly limited as long as it is a resin that can be cured by heat, and a typical example is a phenol resin (eg, phenol resin). Resin emulsion, phenolite PE-402, phenolite TD-224
8, Dainippon Ink Co., Ltd.), unsaturated polyester resin, polyurethane resin (eg, polyurethane resin emulsion, Superflex 410, manufactured by Daiichi Kogyo Co., Ltd.), urea resin (eg, ply set TD-2712S, ply set P -364-BL, Beckamine N-15C, manufactured by Dainippon Ink and the like, melamine resin (eg, Beckamine J-10)
3, Dainippon Ink Co., Ltd.), epoxy resin (eg, Epicron 850, Dainippon Ink Co., Ltd.), diallyl phthalate resin, silicon resin, polyimide resin and the like.

As the flame retardant used in the present invention, a flame retardant which is generally considered to have a flame retardant effect can be used, and in addition to a halogen-based flame retardant, a phosphorus-based flame retardant, an inorganic flame retardant and the like. Reaction-type flame retardants such as phosphorus-containing polyols and halogen-containing organic compounds are exemplified. Examples of the halogen-based flame retardant include bromine such as tetrabromobisphenol A (TBA) and derivatives thereof, hexabromobenzene, decabromodiphenyl ether, tetrabromoethane (TBB), tetrabromobutane, and hexabromocyclodecane (HBCD). System and chlorinated paraffin, diphenyl chloride, perchloropentacyclodecane,
Chlorine such as chlorinated naphthalene is exemplified. These are 1
Species or two or more species may be used in combination.

The phosphorus-based flame retardants include trischloroethyl phosphate (CLP), trisdichloropropyl phosphate (CRP), tricresyl phosphate (TCP), tri (β-chloroethyl) phosphate, and tri (dibromopropyl). Phosphate, a few
And phosphoric esters such as -dibromopropyl-2,3-chloropropyl phosphate and halogenated phosphoric esters.

Examples of the inorganic flame retardants include aluminum hydroxide, magnesium hydroxide, zirconium hydroxide, basic magnesium carbonate, dolomite, hydrotalcite, calcium hydroxide, barium hydroxide, hydrate of tin oxide, borax. Inorganic metal hydrates such as zinc borate, zinc metaborate, barium metaborate, zinc carbonate, magnesium-calcium carbonate, calcium carbonate, barium carbonate,
Examples include magnesium oxide, molybdenum oxide, zirconium oxide, tin oxide, antimony oxide, and red phosphorus. These may be used alone or in combination of two or more.

The antioxidant used in the pressure-sensitive adhesive composition of the present invention includes those generally referred to as antioxidants and antioxidants, and specifically includes, for example, alkylphenols and alkylenes. bisphenol, alkylphenol-thioethers, beta, beta ^'- thiopropionic esters, organic phosphate esters, Allyn salt (nonyl - and condensation thoria phosphate dinonyl phenol), aromatic amines, phenols, nickel complexes And other amine derivatives (ketone-amine condensate,
Diallyldiamine, diallylamine, ketone-diallylamine condensate), phenol derivative, wax, sulfide (dilaurylthiodipropionate, distearylthiodipropionate), metal salt of dithioic acid (metal salt of dithioic acid), and the like. it can. These may be used alone or in combination of two or more.

As a commercially available polyphenol-based antioxidant (manufactured by Ouchi Shinko Chemical Co., Ltd.), Nocrack NS-7 (2,
5-di-tert-butylhydroquinone), nocrack DAH (2,5-di-tert-amylhydroquinone), as a benzimidazole antioxidant, nocrack MB (2-mercaptobenzimidazole), nocrack MMB (2-mercaptomethyl benzimidazole), NOCRAC MBZ (2-mercapto-Benz zinc salt of imidazole) as bisphenol antioxidant, Nocrac NS-5 (2,2 ^'- methylenebis (4
- ethyl -6-tert-butylphenol), Nocrac NS-6 (2, 2 ^'- methylenebis (4-methyl -
6-tert-butylphenol), Nocrack NS-
30 (4,4 ^'- butylidenebis (3-methyl -6-t
tert-butylphenol), Nocrack NS-300
(4,4 ^'- thiobis (3-methyl -6-tert-butylphenol), NOCRAC PBK (p-cresol and butylated reaction product of dicyclopentadiene) and the like can be illustrated,

Commercially available phenolic primary antioxidants (manufactured by Sumitomo Chemical Co., Ltd.) include Sumilizer BHT and Sumilizer BHT-P (2,6-di-tert-butyl-4-).
Methylphenol), Sumilizer S (styrenated phenol), Sumilizer BP-76 (n-octadecyl 3- (3 ^{', 5'} - di -tert- butyl 4 ^'- hydroxyphenyl) - propionate), Sumilizer M
DP-S (2, 2 ^'- methylene - bis - (4-methyl -
6-tert-butylphenol), Sumilizer GM
(2-tert-butyl-6-(3 ^{'-tert-butyl-5'} - methyl-2 ^{'hydroxybenzyl)} -4-methylphenyl acrylate), Sumilizer BBM-S
(4,4 ^'- butylidene - bis - (3-methyl -6-t
ert-butylphenol), Sumilizer WX-R
(4,4 ^'- thio - bis - (3-methyl -6-tert
-Butylphenol), Sumilizer BP-179, Sumilizer BP-101, Sumilizer GA-80, and the like. As the amine-based primary antioxidant,
Sumilizer MXA (mixed N, N ^'- diallyl - phenylenediamine), etc. can be mentioned Sumilizer 9A (alkylated diphenylamine), organic sulfur 2
The next antioxidants, Sumilizer TPL-R (diallyl 3,3 ^'- thiodipropionate), Sumilizer TPM, Sumilizer TPS, Sumilizer TP-D,
Sumilizer TL, Sumilizer MB and the like, and as a phosphite-based secondary antioxidant, Sumilizer TNP (trisnonylphenylphosphite), Sumilizer TPP-R, Sumilizer P-16
And the like, and examples of the composite antioxidant include Sumilizer AZ, Sumilizer MP-S, and Sumilizer BP-225.

The ultraviolet absorber used in the pressure-sensitive adhesive composition of the present invention is a broadly defined ultraviolet absorber including an ultraviolet stabilizer, and specifically, for example, a salicylic acid ester such as phenyl salicylate ( Example: Salol),
2- (5-methyl-2-hydroxyphenyl) benzotriazole (eg, TINUVIN P, Ciba Specialty Chemicals), 2- [2-hydroxy-3,5-
Bis (alpha, alpha ^'- dimethylbenzyl) phenyl] -2H-
Benzotriazole (eg, TINUVIN 234, Ciba Specialty Chemicals), 2- (3,5-di-tert-butyl-2-hydroxyphenyl) benzotriazole (eg, TINUVIN 320, Ciba Specialty Chemicals), 2- (3-tert-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole (eg, TINUVIN 32
6, 326FL, Ciba Specialty Chemicals), 2- (3,5-di-tert-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole (eg, TINUVIN 327, 327FL, Ciba Specialty Chemicals), 2- (3,5-di-te
rt-amyl-2-hydroxyphenyl) benzotriazole (eg, TINUVIN 328, Ciba Specialty Chemicals), 2- (2′-hydroxy-5 ′)
Benzotriazoles such as -tert-octylphenyl) benzotriazole (eg, TINUVIN 329, 329FL, Ciba Specialty Chemicals), 2-hydroxybenzophenone, 2-hydroxy-
4-methoxybenzophenone (eg, Cyasorb U
V-9), hydroxybenzophenones such as 2-hydroxy-4-octoxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone (eg, Cyasorb UV-24), and UvinulN-3
5, N-539, [2,2′-thiobis (4-tert
-Octylphenolate) -n-butylamine nickel (eg, Cyasorb UV-1083), dimethyl-
p-Methoxybenzylidine malonate and the like can be mentioned.

In the present invention, among these ultraviolet absorbers, a benzotriazole-based ultraviolet absorber can be preferably used because of its large synergy with other components.

The mixing ratio of the thermosetting resin and the flame retardant to the non-peelable adhesive base is not particularly limited, but preferably 5 to 40 parts by mass of the thermosetting resin to 100 parts by mass of the non-peelable adhesive base. Parts, more preferably 15 to 25 parts by mass,
5 to 20 parts by mass of a flame retardant, more preferably 8 to 15 parts by mass, 0.5 to 5 parts by mass of an antioxidant, more preferably 2 to 5 parts by mass
4 parts by mass, 0.1 to 1 part by mass of an ultraviolet absorber, more preferably 0.3 to 0.6 part by mass. If the amount of the thermosetting resin is less than 5 parts by mass, the heat resistance may not be improved, and even if the amount exceeds 40 parts by mass, the improvement of the heat resistance does not progress further, and it becomes uneconomical. If the amount of the flame retardant is less than 5 parts by mass, the heat resistance may not be improved, and if the amount exceeds 20 parts by mass, the improvement of the heat resistance does not further progress. On the other hand, if the amount of the antioxidant is less than 0.5 part by mass, the air oxidation resistance may not be improved, and if the amount exceeds 5 parts by mass, the improvement of the air oxidation resistance does not further progress. Also, the ultraviolet absorber is 0.1
If the amount is less than 1 part by mass, the UV resistance may not be improved. If the amount is more than 1 part by mass, the improvement in the UV resistance does not further progress.

The vulcanizing agent for the natural rubber latex includes organic peroxides, metal oxides, sulfur, metal halides,
Amines are used, and among them, organic peroxides are preferably used.

The pressure-sensitive adhesive composition of the present invention may contain, if necessary, a finely divided filler exhibiting non-affinity for the non-peelable adhesive base. As the finely divided filler, those having a small affinity with the adhesive base, for example, zinc oxide, titanium oxide, calcium carbonate, kaolin, activated clay, spherical alumina, wheat starch, silica, glass powder, shirasu balloon and the like are used. . These materials are
They may be used alone or in combination of two or more, but a combination of silica and another filler is particularly preferred. When two or more kinds of particles having different particle diameters are used in combination, the surface of the adhesive layer is easily formed in an uneven shape, which is advantageous in improving the blocking resistance and the peeling performance. By adding the silica, the coating film of the adhesive can be strengthened, and since the silica is porous, the adhesive easily adheres to the surface, and the adhesive force and the peeling force are easily adjusted. These finely divided fillers have an average particle diameter of 10 nm to 30 μm, preferably 1 μm to 20 μm.

The pressure-sensitive adhesive composition of the present invention may further contain a water-soluble polymer, if necessary. The water-soluble polymer may be a natural product, a synthetic product, or a mixture thereof. For example, polymethyl methacrylate, polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HE)
C), casein, starch and the like. The purpose of adding a water-soluble polymer to the pressure-sensitive adhesive composition of the present invention is mainly to improve the surface strength of the adhesive. This also has the effect of improving the fixability of the filler to a base sheet such as paper or paper.

To the pressure-sensitive adhesive composition of the present invention, other synthetic resins and rubbers or other usual additives such as pigments, dyes, lubricants, foaming agents and the like are further added without departing from the gist of the present invention. No problem.

The pressure-sensitive adhesive sheet of the present invention is applied to various types of postcards such as three-folded postcards, two-folded postcards, and partially folded type postcards, and cards. These postcards,
As an example of a card or the like, for example, in the case of a three-fold postcard shown in FIG. 1, first, as shown in FIG. After the bonding, the portion provided with the adhesive layer 1 on the surface is folded along the dotted line portion 3 ', and is overlapped and adhered to the adhesive layer 1, and the two-fold postcard shown in FIG. In the case of the partially folded type postcard 3, as shown in FIGS. 6 and 7, the portion provided with the adhesive layer 1 on one side is folded along the dotted line portion 3 ′, and the adhesive layer surfaces are overlapped and adhered. Is what you do. In the case of the type shown in FIG. 4, the adhesive layers 1 and 2 are provided on the overlapping surfaces, and the surfaces are overlapped and bonded.

In FIG. 1 and FIG. 2, the adhesive layers 1 and 2
May be in this state, but the pressure-sensitive adhesive composition of the present invention may be applied over the periphery of the paper transfer hole to provide an adhesive layer on the entire surface.

The case where the pressure-sensitive adhesive sheet of the present invention is used as a postcard has been described above as an example. However, the present invention can be widely applied to various other notification cards and the like. For example, an adhesive layer is provided on the entire back surface of the sheet. After printing and writing the information on the front side, fold it in half and glue the adhesive layer to create a sheet with information on both front and back sides, peel off the adhesive surface when necessary, and put the information surface on the same surface The adhesive layer may be appropriately provided on the entire front surface and the rear surface, or on the entire surface or a part of the single surface, depending on the folded form of the sheet and the purpose of use, such as developing, organizing, and preserving the sheet. Further, in order to easily perform peeling after bonding, a configuration may be made such that a step is generated in the sheet overlapped at the end opposite to the folded portion of the sheet, and a finger hook portion may be formed, or one end side Alternatively, a non-adhesive portion may be formed to form a finger hook portion.

The pressure-sensitive adhesive composition of the present invention is applied to the surface of the base sheet by a coating means such as a gravure coater, flexo, air knife coater, bar coater, etc. Or suitable for postcards, spreadsheets, notices, various cards, etc. that have a double-sided surface that temporarily adheres, but can be easily peeled off as needed, in the form of various superpositions such as superposition of separate bodies Available to

The base sheet to which the pressure-sensitive adhesive composition of the present invention is applied may be, in addition to ordinary paper, synthetic paper or polyethylene, polyethylene terephthalate, polypropylene,
Synthetic films such as vinyl chloride may be used. When these are used, the surface of the base sheet may be subjected to a surface treatment such as a mat treatment or a corona treatment. The amount of the pressure-sensitive adhesive composition of the present invention applied to the surface of the base sheet is from 1 to 30 in order to maintain the adhesiveness, peelability or transparency of the adhesive layer.
g / m ^2, preferably 3 to 20 g / m ^2, more preferably preferably set to 5 to 15 g / m ^2. Furthermore, about 0.1 to
By applying a pressure of 0.98 Pa, the blocking resistance can be further improved.

Further, the peelable adhesive layer formed by the pressure-sensitive adhesive composition of the present invention itself has the receptivity of printing ink and toner, and if necessary, can be further printed on the surface by ordinary printing. The additional information (not shown) can be printed by a device or a non-impact printer.

[0033]

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. The physical properties of the pressure-sensitive adhesive composition in each example were evaluated by the following methods.

(1) Adhesive strength: Kent paper solid-printed over the entire surface is cut into 25 mm width and 100 mm length to prepare a sample, and these two samples are overlapped with a length of 25 mm to apply a load of 4.9 Pa. , And pressure-bonded, and the peel adhesion (F1) (mN / 25 mm) was measured using Autograph AGS50 (manufactured by Shimadzu Corporation). (2) Heat resistance: A Kent paper solid-printed over the entire surface is cut into a width of 25 mm and a length of 100 mm to prepare a sample, and two samples are overlapped with a length of 25 mm.
After applying a load of 9 Pa and pressure bonding, heating at 120 ° C. for 30 minutes (heating by sandwiching between two stainless steel plates heated to 120 ° C.), and peeling adhesive force using Autograph AGS50 (manufactured by Shimadzu Corporation) ( F2) (mN / 25 mm) was measured. (3) Air oxidation resistance: Kent paper solid-printed over the entire surface was cut into 25 mm width and 100 mm length to prepare a sample, and two samples were overlapped with a length of 25 mm to apply a load of 4.9 Pa. , And stored for 7 days while blowing air in a 40 ° C constant temperature bath, and then using an Autograph AGS50 (manufactured by Shimadzu Corporation) to peel and bond (F)
3) (mN / 25 mm) was measured. (4) UV resistance: A Kent paper solid-printed over the entire surface was cut into 25 mm width and 100 mm length to prepare a sample, and the printed surface of the sample was irradiated with ultraviolet light for about 1 second with an 8 kW high-pressure mercury lamp (15 m). / Min and the sample was placed on a belt conveyor and irradiated with ultraviolet light). UV-irradiated sample 2
The sheets were overlapped with a length of 25 mm and pressed under a load of 4.9 Pa, and then peeled off using an Autograph AGS50 (manufactured by Shimadzu Corporation) (F4) (mN / 25 mm).
Was measured.

Example 1 A natural rubber-based non-peelable adhesive base was prepared by mixing a tackifier, a synthetic rubber for adjustment, a synthetic resin, and the like with a natural rubber latex obtained by graft copolymerization of 15% by mass of methyl methacrylate. Was prepared. 20 parts by mass of a thermosetting resin (Phenolite PE-402 (phenolic resin emulsion), manufactured by Dainippon Ink), 100 parts by mass of the non-peelable adhesive base, and a flame retardant (ANFRAM 3PX, Trischloroethyl) Phosphate (CL
P) Flame retardant, 10 parts by mass of NOF Corporation, 3 parts by mass of antioxidant (Sumilyzer GD, manufactured by Sumitomo Chemical Co., Ltd.), 0.5 parts by mass of UV absorber (Tinuvin 234, manufactured by Ciba Specialty Chemicals) To prepare the pressure-sensitive adhesive composition of the present invention, and the peel adhesive strength (F1), the peel adhesive strength (F2), the peel adhesive strength (F3) and the peel adhesive strength (F)
Table 1 shows the measurement results of 4).

(Examples 2 to 5) The pressure-sensitive adhesive composition of the present invention was prepared in the same manner as in Example 1 at the compounding ratio shown in Table 1, and the peel adhesive strength (F1) and the peel adhesive strength (F2) were prepared. Table 1 shows the results of measuring the peel adhesion (F3) and the peel adhesion (F4).

(Comparative Example 1) Peel adhesion using only the natural rubber-based non-peelable adhesive base prepared in Example 1 without blending a thermosetting resin, a flame retardant, an antioxidant and an ultraviolet absorber. Force (F1), peel adhesion (F2), peel adhesion (F
Table 1 shows the results of measuring 3) and the peel adhesion (F4).

(Comparative Example 2) A pressure-sensitive adhesive composition for comparison was prepared in the same manner as in Example 1 except that the thermosetting resin was not blended, and the peel adhesion (F1) and the peel adhesion were measured. (F2), peel adhesion (F3) and peel adhesion (F
Table 1 shows the measurement results of 4).

(Comparative Example 3) A pressure-sensitive adhesive composition for comparison was prepared in the same manner as in Example 1 except that the flame retardant was not added, and the peel adhesive strength (F1) and the peel adhesive strength (F) were prepared.
2) Table 1 shows the results of measuring the peel adhesion (F3) and the peel adhesion (F4).

(Comparative Example 4) A pressure-sensitive adhesive composition for comparison was prepared in the same manner as in Example 1 except that the antioxidant was not blended, and the peel adhesion (F1) and the peel adhesion ( F
2) Table 1 shows the results of measuring the peel adhesion (F3) and the peel adhesion (F4).

(Comparative Example 5) A pressure-sensitive adhesive composition for comparison was prepared in the same manner as in Example 1 except that no ultraviolet absorber was blended, and the peel adhesion (F1) and the peel adhesion ( F2), peel adhesion (F3) and peel adhesion (F
Table 1 shows the measurement results of 4).

[0042]

[Table 1]

From Table 1, it can be seen that the pressure-sensitive adhesive compositions of the present invention of Examples 1 to 5 are not only initially heated when the cured layers are brought into contact with each other and applied with a predetermined pressure, but also heated after the adhesion. It can be seen that, even after being heated to a high temperature in the air after application or being irradiated with ultraviolet rays, it has a sufficient adhesive strength, and is excellent in all of heat resistance, air oxidation resistance and ultraviolet resistance. On the other hand, the pressure-sensitive adhesive composition of Comparative Example 1 is inferior in all of heat resistance, air oxidation resistance, and ultraviolet resistance,
The pressure-sensitive adhesive compositions of Comparative Examples 2 and 3 are inferior in heat resistance, the pressure-sensitive adhesive compositions of Comparative Example 4 are inferior in air oxidation resistance, and the pressure-sensitive adhesive compositions of Comparative Example 5 Is inferior in UV resistance.

[0044]

According to the pressure-sensitive adhesive composition of the present invention, a thermosetting resin, a flame retardant, an antioxidant, and an ultraviolet absorber are blended with a non-peelable adhesive base. Due to the synergistic action of the components, the cured layers are brought into contact with each other by applying a predetermined pressure and bonded, as well as being heated after bonding, heated to a high temperature in the air after bonding, or irradiated with ultraviolet rays. It has a sufficient adhesive strength even if it is used, and has excellent heat resistance, air oxidation resistance, and UV resistance. The pressure-sensitive adhesive sheet having an adhesive layer formed by applying the pressure-sensitive adhesive composition of the present invention to the surface of the base sheet and having a double-sided surface that can be temporarily bonded but can be easily peeled off when necessary is a cured layer. Of course, at the beginning of contacting each other and applying a predetermined pressure and bonding them together, of course, after bonding, they are heated or heated in air after bonding,
Alternatively, it has a sufficient adhesive strength even when irradiated with ultraviolet rays, so that it has a good concealing property.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an example of a postcard system having confidentiality.

FIG. 2 is an explanatory diagram showing an example of another embodiment of a postcard system having confidentiality.

FIG. 3 is an explanatory diagram showing an example of another embodiment of a postcard system having confidentiality.

FIG. 4 is an explanatory diagram showing an example of another embodiment of a postcard system having confidentiality.

FIG. 5 is an explanatory view of a folded state in FIG. 1;

FIG. 6 is an explanatory view of a folded state in FIG. 2;

FIG. 7 is an explanatory view of a folded state in FIG. 3;

[Explanation of symbols]

 1 pressure-sensitive adhesive composition layer 2 pressure-sensitive adhesive composition layer 3, 3 'fold line

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Emiko Somon 1-1-10 Sengawacho, Chofu City, Tokyo (72) Inventor Masami Ichikawa 1-16-16 Ojida, Yokkaichi City, Mie Prefecture Inside E-Tech Co., Ltd. 72) Inventor Manabu Shimizu 1-6-16 Ojita, Yokkaichi-shi, Mie F-term in E-Tech Co., Ltd. (reference) DA141 DC021 DE021 DE031 DE042 DF041 DL011 EB032 EB112 EB132 EC002 ED112 EF001 EF002 EH032 EJ011 EK032 HA056 HA136 HA156 HA196 HA326 HA356 HB05 HB06 HB19 HB33 HB36 HC01 HC25 HD05 HD24 JA03 JA09 LA08

Claims (3)

[Claims] 1. A pressure-sensitive adhesive composition comprising a non-peelable adhesive base, a thermosetting resin, a flame retardant, an antioxidant, and an ultraviolet absorber. 2. A thermosetting resin, 5 to 40 parts by mass, a flame retardant, 5 to 20 parts by mass, and an antioxidant, 0.5 to 5 parts by mass, based on 100 parts by mass of the non-peelable adhesive base. 2. The composition according to claim 1, further comprising 0.1 to 1 part by mass of an ultraviolet absorber.
The pressure-sensitive adhesive composition according to the above. 3. A pressure-sensitive adhesive sheet having a coating layer of the pressure-sensitive adhesive composition according to claim 1 on at least a part of a surface of a base sheet.