JPS6032872A - Adhesive composition - Google Patents

Abstract

PURPOSE:The titled composition applicable to a substrate sheet without using a solvent, providing high tack and cohesive force by irradiation of ionizingn radiation with low dose, comprising a terminal mercapto group-containing vinyl polymer and a vinyl monomer as main components. CONSTITUTION:(A) 50-90pts.wt. vinyl polymer [preferably acrylic acid ester polymer shown by the formula I (R<1> is H, or methyl; R<2> is 2-14C alkyl), having 10,000-100,000 weight-average molecular weight calculated as styrene] containing a mercapto group at one end or both ends is blended with (B) preferably 50-10pts.wt. vinyl monomer [preferably acrylic acid ester monomer shown by the formula II (R<3> is 2-14C alkyl)], to give the desired composition.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to an adhesive substance that has both high adhesive strength and cohesive force when irradiated with a relatively low dose of ionizing radiation, that is, an adhesive substance that has the property of forming an adhesive layer. The object of the present invention is to provide a novel adhesive substance that can be coated onto a base sheet in a substantially solvent-free state when producing pressure-sensitive adhesive tapes, adhesive sheets, and the like.

(Prior art) Conventionally, pressure-sensitive adhesive tapes and adhesive sheets are made of rubber-based polymers such as natural rubber or synthetic rubber, or acrylic polymers such as polyacrylic acid ester, and a tackifier-1 softener.
It is manufactured by applying an organic solvent solution or water mixture of an adhesive composition containing an anti-aging agent, etc. onto a base sheet and drying it by heating. There is a risk of fire due to ignition, toxicity to workers, etc., and products that use a water mixture have a long drying time (takes a long time), consumes a lot of energy, and the resulting adhesive tapes There are disadvantages such as poor water resistance of the pressure-sensitive adhesive layer and difficulty in applying the film when using it as a base sheet.In addition, generally, the pressure-sensitive adhesive composition contains An incyanate compound was added as a crosslinking agent, and a coating agent consisting of the organic solvent solution or water mixture containing the adhesive composition was applied to the base sheet and then heated to introduce a crosslinked structure. By forming an adhesive layer, cohesive force, heat resistance, and solvent resistance are imparted to the adhesive layer, and the adhesive obtained from an adhesive composition containing such a thermal crosslinking agent The agent layer also has the disadvantage that its storage stability is extremely poor, which limits its use.

For this reason, it is necessary to eliminate the drawbacks of the prior art (for example, as a solvent-free adhesive material that does not contain a thermal crosslinking agent, acrylic Acid alkyl ester alone or together with -CO in the side chain
OH, -CN, -COOR.

An adhesive substance made of a mixture with a polymerizable monomer having a polar group such as -CONH2 has been proposed, and after applying the adhesive substance to a base sheet, ionizing radiation is irradiated to form a crosslinked structure. A method of forming an incorporated adhesive layer is described.

By the way, the method for forming the adhesive layer in which a crosslinked structure is introduced by irradiation with ionizing radiation is that 100% solid hardening is possible because the coating agent layer to which ionizing radiation is irradiated is solvent-free. Although it has many advantages such as no air pollution, low energy required for crosslinking, and instantaneous crosslinking reaction, the adhesive material consisting only of monomers proposed in the above patent publication. Although the resulting adhesive layer has sufficient adhesive strength, it is difficult to impart sufficient cohesive strength to the adhesive layer, and a slight improvement is obtained when the irradiation dose of ionizing radiation is increased. It's just a matter of getting caught.

However, in order to overcome the drawbacks of the proposed adhesive materials consisting only of monomers, research has also been carried out on adhesive materials consisting of mixed compositions of non-curable polymers and monomers. However, in order to obtain an adhesive layer with sufficient adhesion and cohesion, the amount of non-curing polymer must be increased (as a result, since it is used as a highly viscous material, the adhesive The coating process of applying the agent material to the base sheet is difficult, and it is often impossible to apply it without a solvent. In order to form a cured adhesive layer, it is necessary to irradiate a high dose of ionizing radiation, which has the disadvantage of not being satisfactory in these respects.

Furthermore, research has been conducted on adhesive substances made of mixed compositions of monomers and polymers having polymerizable unsaturated groups, but in order to cure them by irradiation with low doses of ionizing radiation, It is necessary to introduce a large amount of polymerizable unsaturated groups into the polymer molecule, and by doing so,
Although curing is possible by irradiation with low doses of ionizing radiation,
As a result of the crosslinking density becoming too high, it still has the disadvantage that it cannot exhibit a strong adhesive force.

(Objective of the Invention) Therefore, the object of the present invention is to eliminate the drawbacks of the above-mentioned conventional techniques, and in particular, to form a pressure-sensitive adhesive layer having optical adhesive force and cohesive force by irradiation with a low dose of ionizing radiation. An object of the present invention is to provide a composition for a pressure-sensitive adhesive.

(Structure of the Invention) The gist of the present invention is a pressure-sensitive adhesive composition containing as main components a vinyl polymer having a mercapto group at at least one end and a vinyl monomer. .

The present invention will be explained in detail below.

The first component of the adhesive composition of the present invention is a vinyl polymer having a mercapto group at at least one end.

The vinyl polymer, which is the first component, is a homopolymer of an acrylic acid ester represented by the following general formula (11) or an acrylic ester represented by the following general formula.
It is a copolymer consisting of a heavy weight plate and a monomer other than acrylic acid ester, and has a mercapto group at the end of the molecule.

CH2-C-C00R2 (1) ■ 1 However, in the above general formula (1), R1 is hydrogen or a methyl group.
R2 represents an alkyl group having 2 to 1 carbon atoms. or,
Other monomers used to form the above copolymer include: vinyl acetate, (meth)acrylic acid, maleic anhydride, euhydroxyethyl (meth)acrylic V-) , 2-hydroxypropyl (meth)acrylate, diaseptone acrylamide, acrylamide, N, N-t-butylacrylamide, acrylonitrile.

The molecular weight of the vinyl polymer, which is the first component, is styrene equivalent weight average molecular weight /0.000~
It is preferable that t o t>, o oo. Here, if it is less than 70.000, curing will not be performed sufficiently by irradiation with low doses of ionizing radiation, and even if irradiation with high doses of ionizing radiation is performed, the crosslinking density will be high ( Too much and not enough adhesive strength can be obtained.700.00
When it exceeds 0, the viscosity of the composition becomes too high, so
Application becomes extremely difficult.

The mercapto contained in the vinyl polymer, which is the first component, is attached to one end of the vinyl polymer, which is the first component.

Vinyl polymers with mercapto groups are produced depending on their manufacturing method. Alternatively, a mixture of these can be used, but any of them can be used.

Next, the vinyl monomer, which is the second component of the adhesive composition of the present invention, functions as a viscosity modifier and an adhesive performance modifier in the adhesive composition. For example, an acrylic acid ester monomer represented by the general formula CH2=CHCOOR3 (in the formula, R3 represents an alkyl group having 2 to 4' carbon atoms), (in the formula, R4 is hydrogen or a carbon number/-g represents an alkyl group or a phenyl group, R5 and R6 represent hydrogen or an alkyl group having 3 to 3 carbon atoms, and R5 and Ro may be the same or different (, n is l-coO (in the formula, R7 is hydrogen or an alkyl group having 1 to 3 carbon atoms, R
8 represents an alkyl group having 1 or more carbon atoms, m represents an integer of 1 or more), euhydroxy-3-phenoquine propyl acrylate, acryloyloxyethyl monosuccinate, acryloyloxyethyl Monophthalate or acrylic acid ester monomers such as ethylene glycol diacrylate, polyethylene glycol diacrylate, hexanediol diacrylate, and trimethylolpropane triacrylate are mainly used.

In the adhesive composition of the present invention, the amount of the vinyl polymer as the first component is rO-90 parts by weight, and the amount of the vinyl monomer as the second component is SO to io parts by weight. It is preferable. In the above, the blending amount of the vinyl polymer is less than SO weight part, therefore, the blending amount of the vinyl monomer is SO
If the amount exceeds 1 part by weight, sufficient curing will not be achieved by irradiation with low doses of ionizing radiation, so sufficient cohesive force will not be obtained, and if the amount of vinyl polymer blended is qoN parts, Therefore, if the amount of the vinyl thread monomer is less than the IO overlapping portion, the viscosity of the composition will become too high, making application extremely difficult.

The pressure-sensitive adhesive composition of the present invention basically comprises the first step as described above.
and from the second ingredient (・roga, as necessary)・
Idoquinone, Idoquinone monoethyl ether,
Polymerization inhibitors such as Be/Zoquino 7, benzophenone, N
, N-tetraethyl-<+, lI-diaminobenzophenone, ethyl-gage methylaminobenzoate, etc., can also be added.

Next, the method for producing the adhesive composition of the present invention will be explained. First, a vinyl polymer, which is the first component, is prepared. A predetermined amount of tyt4 or one or more of the acrylic acid esters of the general formula (Il) described above as starting materials for the polymer, or other monomers described above in addition to these, are prepared in a predetermined amount, and the monomers as described above are prepared. Benzoyl peroxide, α,α'-azobisisobutyronitrile, 'A,'%'-azobis(tl-
cyanovaleric acid) or succinic acid peroxide, etc., and a mercaptan having an active hydrogen group such as mercaptoethanol, mercaptopropanol, mercaptoethylamine, mercaptopropionic acid, mercaptosuccinic acid, etc. By adding 0.03-/0.0 parts by weight of 7 or 2 or more of the following, and then dropping it dropwise into a refluxing solvent to cause a polymerization reaction, at least one molecular end , OH group, COOH group, or Nl2 group is prepared, and a polymerization inhibitor such as be/zoquinone or hydroquinone is added to stop the polymerization. After termination of polymerization, a polymerizable unsaturated group can be introduced by condensing or adding the following compounds depending on the group at the end of the molecule of the polymer; (a) When the end of the molecule is an OH group; (b) When the molecular terminal is a C0OH group, it is a condensation reaction with mercaptoethanol, mercaptoethylamine, etc. () → When the molecular terminal is a Nl2 group, it is a mercapto Condensation reaction with propionic acid, etc.; 2) Equimolar reaction product of vinyl cyclohexe/dioxide and mercaptoethylamine, or coccotolelene diincyanate, regardless of whether the molecular terminal is an OH group, COOH group, or Nl2 group. and mercaptoethanol are added.

In addition, it can also be obtained by adding thioepoxides such as ethylene sulfide and propylene sulfide to the terminals of the above polymers.

After introducing the mercapto group, the solvent used during polymerization is removed by heating or heating under reduced pressure.

In addition, in the above, the molecular weight of the polymer can be arbitrarily adjusted by increasing or decreasing the amount of the polymerization initiator and mercaptans added, and as described above (,) o, o o o ~ / 00
．． It is preferable to set it to 0θO.

The obtained vinyl polymer having a mercapto group at the end,
A pressure-sensitive adhesive composition can be prepared by mixing a predetermined amount of a vinyl monomer and other components and uniformly dissolving the mixture preferably using a disilver or a kneader.

The adhesive composition of the present invention having the structure as described above,
In general, a coating method such as roll coating, die coating, knife coating, dip coating, etc., is applied to a base sheet made of paper, plastic film, metal foil, or a laminate film of these materials, for example, to coat a base sheet of about 1O to JOji/rl. applied in proportion,
Thereafter, the adhesive tape is cured by irradiation with ionizing radiation such as X-rays, gamma rays, electron beams, and ultraviolet rays to obtain an adhesive tape having an adhesive layer having excellent adhesive strength and cohesive strength. In the process of mounting the adhesive tape, ionizing radiation is irradiated at 50 to /000 KeV, particularly /00 to .000 KeV.
? An electron beam with an energy of about 00 KeV /
It is preferable to irradiate at a dose of about −2° Mrad. In addition, when irradiating this ionizing radiation, the surface coated with the pressure-sensitive adhesive composition of the present invention is protected with paper or film that has release properties, and the ionizing radiation a is irradiated in a state where oxygen is blocked. Irradiation is preferable because the generated radicals can be effectively utilized.

(Effects) Since the pressure-sensitive adhesive composition of the present invention has the above-described structure, it can be applied substantially without solvent, and it can also be applied with sufficient adhesive strength and It is possible to provide an adhesive layer with cohesive strength.

(Example) Examples for showing the present invention more specifically are listed below.

Example 1 A mixture having the following composition was dropped into a SL flask with refluxing ethyl acetate qsog for about 2 hours while stirring, and after further heating to 80°C for 6 hours, 1 llj of hydroquinone; / was added to stop the reaction.

Mixture CompositionMeanwhile, put in another tl q flask I/C2,'I-toluene diincyanate/74i and bring the temperature to 0.
While controlling the temperature to ~60°C, qg of mercaptoethanol was added dropwise and reacted for 1 hour to obtain an adduct of 2,II-) luene diincyanate and mercaptoethanol.

3 g of the obtained adduct was added to a flask containing the polybutyl acrylate that had been polymerized earlier, and then dibutyl tin dilauryl was added to the flask. J, 9 was added and reacted at 80°C for S hours. The resulting reaction product was desolvented to obtain polybutyl acrylate having a mercapto group at the end.

Next, a pressure-sensitive adhesive composition was obtained by mixing and dissolving the following composition.

Composition for Adhesive The viscosity of the obtained composition was about 13θθ centivoise at gO°C.

The composition was applied to a thickness of 30μ on a polyester film having a thickness of lOμ, and the coating was then subjected to a low energy electron accelerator (Energy 5ci) in an N2 atmosphere.
Manufactured by ence, Electro Curtain CB, 2 o o
/ s o / ,? o) So, electron beam! Mrad'
A film having an adhesive layer which had been polymerized and crosslinked was obtained by irradiation for 7 hours.

Next, a releasable polyethylene laminate paper was laminated on the adhesive layer surface of the film, and then this was
It was cut into a tape shape of mm, and then the adhesive tape obtained by peeling off the polyethylene laminate paper described above was attached to a stainless steel plate (SUS-, 04') and JI
The adhesion strength as a result of the 1gO° beer test specified in S -Z -0,273 is ψgo! A tape having excellent properties as an adhesive tape was obtained.

In addition, the /gO' beer test specified in JIS-Z-0273 is performed using a stainless steel plate (5tJs -,?otI).
After polishing with sandpaper (≠2go), adhesive tape was attached, a 2kg rubber roll was moved back and forth, and after ripening under certain conditions, the adhesive tape was applied to the steel/res.
In this method, the film is folded back and then peeled off at a speed of 300 mm/min, and the peeling force at this time is measured.

Example U In the same manner as in Example 1, the following monomer mixture was polymerized to obtain a copolymer (A)'lr.

Mixed liquid composition Meanwhile, using another flask, add vinyl cyclohexane dioxide/1131, and while controlling the temperature at 60 to 90°C, add mercaptoethylamine yq7sfl'x dropwise to react. obtained an adduct body.

The obtained Adaku-Batai-hi copolymer (in addition to Al, additionally 0
After adding Pyrin 7 of RI I and reacting at a temperature of 30 to 100° C. for 7 hours, the solvent was removed to obtain a copolymer (B) having a mercapto group at the end.

The obtained mercap, a copolymer with a radical (BISO
Parts by weight of SO were mixed with parts by weight of a monofunctional acrylic acid ester monomer [Light Ester DPMA: manufactured by Kyoeisha Yushi Kagaku Kogyo ■] to obtain a pressure-sensitive adhesive composition of the present invention.

Next, the pressure-sensitive adhesive composition is heated to have a viscosity of J 00
70 by gravure coating method while maintaining cps.
g/m' high-quality paper surface to a thickness of 30 μm, and was irradiated with an electron beam in the same manner as the electron beam irradiation method described in Example 1 below to obtain an adhesive that was polymerized and crosslinked. A paper label with layers was obtained.

The obtained paper label was subjected to a beer test in the same manner as described in Example 1, and the adhesive strength was 'l 00 j
i//Omm or more, and had excellent properties as a paper label.

Example 3 Same as Example 1 except that 7 roy of toluene was used instead of 7 roy of ethyl acetate. ;Similarly add O to the terminal using Oji
A polybutyl acrylate having H groups was obtained.

In the obtained polybutyl acrylate solution, β-mercaptopropionic acid (t, sg and P-)/9/7, sulfonic acid 1. ! 9 was added, and an esterification reaction was carried out while removing toluene at /θO°C to 130°C to obtain polybutyl acrylate having a mercapto group at the terminal. Next, a pressure-sensitive adhesive composition having the following composition was prepared.

Parts by Weight of Adhesive Composition S The adhesive strength of the label obtained by applying the above adhesive composition to a SO μm thick polyester film to a thickness of 30 μm and irradiating it with ultraviolet light is as follows: lIt, o
It was l/10 my.

Patent applicant: Dai Nippon Printing Co., Ltd.

Claims (8)

[Claims] (1) A pressure-sensitive adhesive composition containing as main components a vinyl polymer having a mercapto group at at least one end and a vinyl monomer. (2) The pressure-sensitive adhesive composition according to claim (1), which has a mercapto group at one end. (3) The pressure-sensitive adhesive composition according to claim (1), which has a mercapto group at both ends. (4) The polymerizable unsaturated group is an acrylic group, a methacrylic group,
or a vinyl group, the pressure-sensitive adhesive composition according to any one of claims (1) to (3). (5) The adhesive composition according to any one of claims (1) to (4), wherein the vinyl polymer is an acrylic ester polymer. (6) The pressure-sensitive adhesive composition according to claims 11 to 5, wherein the vinyl polymer has a styrene equivalent weight average molecular weight of /0.000 to /00.000. (7) The adhesive composition according to any one of claims (1) to (6), wherein the vinyl monomer is an acrylic acid ester monomer. (8) The pressure-sensitive adhesive according to any one of claims 11 to 7, which is blended in a ratio of 50 to 90 parts by weight of a vinyl polymer and 70 parts by weight of a vinyl monomer SO. Composition for use.