JP5528669B2 - A composition for forming an active energy ray-curable pressure-sensitive adhesive coating film and a peelable adhesive-processed paper using the same. - Google Patents

Description

  The present invention relates to a composition for forming a pressure-bonded coating film that enables releasable adhesion by pressure bonding, and is a composition for forming an active energy ray-curable pressure-bonded coating film that is cured by active energy rays, and a releasable adhesion using the composition. It relates to processed paper.

  In recent years, postcard systems having confidentiality instead of sealed letters have been rapidly spread for the purpose of reducing postage costs, printing information, and creating notifications. In this system, in order to conceal the information content, the paper is folded and the opposing paper surfaces are detachably bonded together. There are various adhesive compositions used for the bonding surfaces, but none of them sufficiently satisfies the surface gloss, work efficiency, paper recycling, storage stability, production cost, and the like.

  In order to improve the glossiness and working efficiency of the surface, at least selected from a (meth) acrylic copolymer having a specific molecular weight and glass transition temperature, and an ultraviolet curable monomer and oligomer having a (meth) acryloyl group It has been proposed to use an adhesive composition containing a kind of ultraviolet curable component and a photopolymerization initiator (Patent Documents 1 and 2).

In addition, an adhesive composition containing a (meth) acryloyl group-containing elastic body having a specific molecular weight, an ultraviolet curable component, and a photopolymerization initiator and having the above three components set to a specific content ratio is used. It is also considered to do (Patent Document 3).
JP-A-11-349854 JP 2000-136320 A JP 2004-210879 A

  However, the adhesive compositions as described in Patent Documents 1 and 2 are in a state where the composition components are mutually mixed and uniformly dispersed, and have excellent coating stability, but have a problem in curability and are slightly bent when bent. May occur. Moreover, the problem that the adhesive force becomes too strong with the passage of time also arises. On the other hand, the adhesive composition of the above-mentioned Patent Document 3 solves such a problem of curability and is excellent in curability, and the adhesive force and the like hardly change over time. And stable adhesiveness was not obtained.

  In addition, the market demands an adhesive composition that is excellent in surface gloss of the printing surface, efficiency of processing work, and cost performance of manufacturing processed paper.

  The present invention has been made in view of such circumstances, and is intended to improve the efficiency of processing work by eliminating the need for a good coating and drying process during coating, and enables good curing, An object of the present invention is to provide a composition for forming an active energy ray-curable pressure-sensitive adhesive coating film that has excellent adhesive strength after curing and excellent releasability at the time of peeling, and a releasable adhesive-processed paper using the same.

In order to achieve the above object, the present invention includes a carboxyl group-containing acrylic polymer (A), the following (b1) to (b3), and the content ratio of the following (b1) to (b3) is an active energy. Active energy ray-curable component ( b1) is 5 to 20% by weight, (b2) is 40 to 80% by weight, and (b3) is 10 to 40% by weight based on the whole of the wire-curable component (B) ( B), an active energy ray-curable pressure-sensitive adhesive film-forming composition containing a photopolymerization initiator (C), wherein the content of the carboxyl group-containing acrylic polymer (A) is the active energy ray. 5 to 45 parts by weight with respect to 100 parts by weight of the curable component (B), and the content of the photopolymerization initiator (C) is 10 with respect to 100 parts by weight of the active energy ray-curable component (B). Active energy ray that is ~ 30 parts by weight The reduction crimp coating forming composition to the first aspect.
(B1) At least one of epoxy (meth) acrylate and urethane (meth) acrylate.
(B2) An ethylenically unsaturated compound other than (b1) having two or more ethylenically unsaturated groups.
(B3) An ethylenically unsaturated compound other than (b1) having one ethylenically unsaturated group.

  Moreover, in this invention, let the said peelable adhesive processed paper by which the said active energy ray hardening-type composition for pressure-bonding coating-film formation is coated on the paper surface, and is hardened | cured with the active energy ray is made into a 2nd summary.

(Background to the present invention)
That is, in order to obtain an adhesive composition having excellent coating and curability and excellent peelability, the present inventors have conducted intensive studies in view of the above circumstances, the acrylic polymer (A), and the above The active energy ray-curable component (B) containing (b1) to (b3 ) and the photopolymerization initiator (C) were mainly studied. As a result, the acrylic polymer is allowed to contain a carboxyl group, and the photopolymerization initiator (C) is set at a specific ratio higher than the conventional ratio in relation to the curing component, thereby achieving good coating. The present invention has been completed by finding that an active energy ray-curable pressure-sensitive adhesive film-forming composition having good adhesion and excellent peelability can be obtained. In general, since the cured product is too increased the photopolymerization initiator (C) is a low molecular weight, where there tends to reduce the content of the photopolymerization initiator (C) is set larger than conventional content At the same time, it has been found that an excellent adhesive composition for peelable adhesive processed paper can be obtained by incorporating a carboxyl group into the acrylic polymer (A) .

  The mechanism for obtaining such an effect is considered as follows. In general, the folded sheet-like postcards used in the postcard system are pressed together so that the fine silica gel particles adhered to the paper bite into each other, so that the paper surfaces stick to each other. Since they do not mesh with each other, they do not stick again. In the present invention, by using a large amount of photopolymerization initiator, a finer sea-island structure is created on the surface after curing, and by acting as the silica gel, good press adhesion (after peeling) It is considered that it exhibits re-adhesion prevention property. In addition, by including carboxyl groups in the acrylic polymer, the distance between the carboxyl groups is reduced by pressing, and the adhesive force is increased by becoming a distance that allows interaction (hydrogen bonding). On the other hand, carboxyl groups are sterically hindered. Therefore, it is considered that the adhesive force can be prevented from increasing to such an extent that peeling becomes difficult.

As described above, the present invention contains the carboxyl group-containing acrylic polymer (A), the following (b1) to (b3), and the content ratio of the following (b1) to (b3) is active energy ray curable. Active energy ray-curable component (B) in which (b1) is 5 to 20% by weight, (b2) is 40 to 80% by weight, and (b3) is 10 to 40% by weight, based on the entire component (B), Containing a photopolymerization initiator (C), the content of the carboxyl group-containing acrylic polymer (A) is 5 to 45 parts by weight with respect to 100 parts by weight of the active energy ray-curable component (B), Active energy ray-curable pressure-sensitive adhesive coating, wherein the content of the photopolymerization initiator (C) is 10 to 30 parts with respect to 100 parts by weight (hereinafter referred to as “parts”) of the active energy ray-curable component (B). It is a composition for film formation. Therefore, it eliminates the need for good coating and a drying process during coating, improves the efficiency of the processing work, and enables good curing, and has excellent adhesive strength after curing and good at the time of peeling. It comes to have peelability. Therefore, the peelable adhesive processed paper using this has such excellent adhesive force and peelability, and is highly practical.
(B1) At least one of epoxy (meth) acrylate and urethane (meth) acrylate.
(B2) An ethylenically unsaturated compound other than (b1) having two or more ethylenically unsaturated groups.
(B3) An ethylenically unsaturated compound other than (b1) having one ethylenically unsaturated group.

  Moreover, when the weight average molecular weight of the carboxyl group-containing acrylic polymer (A) is 100,000 or less, the coatability is further improved.

  When the glass transition temperature of the carboxyl group-containing acrylic polymer (A) is in the range of −60 to 20 ° C., the resulting adhesive layer has excellent flexibility.

  Next, embodiments of the present invention will be described in detail. However, the present invention is not limited to this embodiment.

The composition for forming an active energy ray-curable pressure-sensitive adhesive coating film of the present invention (hereinafter sometimes abbreviated as “composition for forming a pressure-sensitive adhesive coating film”) is a carboxyl group-containing acrylic polymer (A), active energy ray-curing property. A composition for forming a pressure-bonded coating film comprising a component (B) and a photopolymerization initiator (C), and active energy such as ultraviolet rays, infrared rays, electromagnetic waves such as X-rays and γ rays, and electron beams Curing with wire.
First, the carboxyl group-containing acrylic polymer (A) will be described.

<< Carboxyl group-containing acrylic polymer (A) >>
The carboxyl group-containing acrylic polymer (A) used in the present invention is obtained by copolymerizing a (meth) acrylic acid alkyl ester (a1) and a carboxyl group-containing monomer (a2). The copolymerizable monomer (a3) may be copolymerized.

  In the present invention, (meth) acrylic acid is acrylic acid or methacrylic acid, (meth) acryl is acrylic or methacrylic, (meth) acryloyl is acryloyl or methacryloyl, and (meth) acrylate is acrylate or Each means methacrylate.

  Examples of the (meth) acrylic acid alkyl ester (a1) include nonyl (meth) acrylate, n-octyl (meth) acrylate, iso-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and n-butyl ( Examples include meth) acrylate, iso-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-propyl (meth) acrylate, methyl (meth) acrylate, and ethyl (meth) acrylate. Among these, (meth) acrylic acid alkyl esters having 1 to 10 carbon atoms in the alkyl group are preferably used, and (meth) acrylic acid alkyl esters having 1 to 5 carbon atoms in the alkyl group are particularly preferably used. . Of these, ethyl (meth) acrylate and n-butyl (meth) acrylate are particularly preferably used. One or more of these (meth) acrylic acid alkyl esters (a1) are used.

  Examples of the carboxyl group-containing monomer (a2) include (meth) acrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, fumaric acid, acrylamide-N-glycolic acid, cinnamic acid, and (meth) acrylic. Michael adduct of acid (for example, acrylic acid dimer, methacrylic acid dimer, acrylic acid trimer, methacrylic acid trimer, acrylic acid tetramer, methacrylic acid tetramer, etc.), 2- (meth) acryloyloxyethyl dicarboxylic acid monoester (for example, 2 -Acryloyloxyethyl succinic acid monoester, 2-methacryloyloxyethyl succinic acid monoester, 2-acryloyloxyethyl phthalic acid monoester, 2-methacryloyloxyethyl phthalic acid monoester, 2-acryloyloxyethyl ester Sahidorofutaru acid monoester, 2-methacryloyloxyethyl hexahydrophthalic acid mono ester) carboxyl group-containing unsaturated monomers such as, and the like. Preferably, (meth) acrylic acid is used. 1 type, or 2 or more types is used for said compound.

  Examples of the other copolymerizable monomer (a3) used as necessary include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-chloro-2-hydroxypropyl acrylate, 2-hydroxyethyl. Methacrylate, 2-hydroxypropyl methacrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, tetrahydrofurfuryl acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, diethylene glycol (meth) acrylate, polyethylene glycol (meth) Hydroxyl-containing unsaturated monomers such as acrylate, N-methylol acrylamide, N-methylol methacrylamide, glycidyl (meth) acrylate, allyl glycidyl (meth) acryl Glycidyl group-containing unsaturated monomers such as t-butylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate and other amino group-containing monomers, 2- (acetoacetoxy) ethyl ( Mono (meth) alkoxy (poly) alkylene glycol (meth) acrylate-containing monomers such as meth) acrylate and allyl acetoacetate, 2-methoxyethyl (meth) acrylate, 3-methoxyethyl (meth) acrylate, methoxydiethylene glycol (meth) acrylate and the like ) Allyl compounds such as acrylates, N- (meth) acrylamidomethyltrimethylammonium chloride, allyltrimethylammonium chloride, dimethylallyl vinyl ketone, Pyrrolidone, vinyl propionate, vinyl stearate, vinyl chloride, vinylidene chloride, vinyl acetate, vinyl monomers such as styrene, acrylonitrile, n- dodecyl mercaptan, and the like. Preferably, acrylonitrile and n-dodecyl mercaptan are used. These can be used alone or in combination of two or more.

  Thus, the carboxyl group-containing acrylic polymer (A) used in the present invention is the above-mentioned (meth) acrylic acid alkyl ester (a1), the carboxyl group-containing monomer (a2), and other copolymers as required. It can be obtained by copolymerizing the functional monomer (a3). As a specific proportion of the copolymer component, the (meth) acrylic acid ester monomer (a1) is 75 to 95% by weight, particularly 80 to 93% by weight, more preferably 85 to 90%, based on the entire copolymer component. It is preferable to contain 1% by weight, particularly 1.5 to 8% by weight, more preferably 2 to 6% by weight of the carboxyl group-containing monomer (a2). It is preferable to contain (a3) in an amount of 5 to 15% by weight, particularly 6 to 14% by weight, and more preferably 7 to 13% by weight.

  The carboxyl group-containing acrylic polymer (A) thus obtained preferably has a weight average molecular weight (Mw) of 100,000 or less, particularly 80,000 or less, more preferably 60,000 or less. . This is because if the weight average molecular weight (Mw) of the carboxyl group-containing acrylic polymer (A) is too large, the resin viscosity increases and the coating property tends to deteriorate.

  On the other hand, the lower limit of the weight average molecular weight (Mw) of the carboxyl group-containing acrylic polymer (A) is preferably 10,000 or more, particularly 20,000 or more, and more preferably 30,000 or more. This is because if the weight average molecular weight (Mw) of the carboxyl group-containing acrylic polymer (A) is too small, the cohesive force of the adhesive obtained by irradiation with active energy rays is insufficient and the adhesiveness tends to be lowered.

  The carboxyl group-containing acrylic polymer (A) can be produced by methods well known to those skilled in the art, such as solution radical polymerization, suspension polymerization, bulk polymerization, and emulsion polymerization. Among them, suspension polymerization is preferably used as a method for producing a carboxyl group-containing acrylic polymer (A) satisfying the above conditions because a polymer having a high degree of polymerization can be obtained and the resulting polymer can be easily isolated. . That is, the carboxyl group-containing acrylic polymer (A) is preferably a dry resin obtained by suspension polymerization.

  In the polymerization, a polymerization initiator such as azobisisobutyronitrile can be added as necessary.

  In the present invention, the glass transition temperature (Tg) of the carboxyl group-containing acrylic polymer (A) is preferably −60 to 20 ° C. or less, particularly −60 to 0 ° C., more preferably −55 to − It is preferable that it is 10 degrees C or less. This is because if the glass transition temperature (Tg) of the acrylic polymer (A) is too low, the cohesive force tends to be inferior, and conversely if too high, the adhesive tends to become brittle.

In the present invention, the weight average molecular weight is a weight average molecular weight in terms of standard polystyrene molecular weight, and is a high performance liquid chromatography (manufactured by Waters, Japan, “Waters 2695 (main body)” and “Waters 2414 (detector)”). Column: Shodex GPC KF-806L (exclusion limit molecular weight: 2 × 10 ⁷ , separation range: 100 to 2 × 10 ⁷ , theoretical plate number: 10,000 plates / pack, packing material: styrene-divinylbenzene copolymer , The particle diameter of the filler: 10 μm). The glass transition temperature is calculated from the Fox equation.

The content of the carboxyl group-containing acrylic polymer (A), Ri 5 to 45 parts der the active energy ray-curable component (B) 100 parts described below, in particular 7-35 parts, more 10 It is preferably 25 parts. When the content of the carboxyl group-containing acrylic polymer (A) is too small, Ri such sufficient adhesive property is obtained kuna, and an excessively large, the crimp coating forming composition of the present invention obtained stickiness with sensitive becomes strong, also lowered glossiness, or paper tear occurs in the adhesion too strong at the time of peeling, it is Luke et al to shortage of blocking resistance of the coated paper.

<< Active energy ray-curable component (B) >>
The active energy ray-curable component (B) is a component for curing reaction by active energy rays is caused, at least one of d epoxy (meth) acrylate and urethane (meth) acrylate and (b1), an ethylenically unsaturated group 2 Ethylene-unsaturated compound (b2) other than (b1) having at least one (hereinafter sometimes abbreviated as “polyfunctional compound (b2)”) and ethylene other than (b1) having one ethylenically-unsaturated group Active energy ray-curable component containing a polymerizable unsaturated compound (b3) [hereinafter sometimes abbreviated as “monofunctional compound (b3)”] . Thus , containing all the three components (b1) to (b3) has excellent adhesive force and good releasability at the time of peeling , and the polyfunctional compound (b2) and monofunctional compound (b3) Are preferably used in combination of two or more in terms of promoting the curing reaction. Moreover, it is more preferable that the content of the polyfunctional compound (b2) is larger than the content of the monofunctional compound (b3) because sufficient resin cohesion can be obtained.
Next, the components (b1) to (b3) will be described.

<At least one of epoxy (meth) acrylate and urethane (meth) acrylate (b1)>
In the present invention, it is preferable to contain at least one of epoxy (meth) acrylate and urethane (meth) acrylate (b1) as a constituent compound of the active energy ray-curable component (B).

  The above-mentioned epoxy (meth) acrylate can be cured at high speed even when the amount of ultraviolet rays is low, and when blended with epoxy (meth) acrylate, the mechanical properties of the product are excellent in fatigue resistance such as bending and impact during postcard products. This is because it tends to be excellent. That is, epoxy (meth) acrylate is excellent in fast curability and adhesive film toughness.

  The urethane (meth) acrylate has a flexible molecular skeleton, so it can give the product properties such as flexibility and high elasticity, and has a large tensile elongation as a mechanical property, such as bending and impact during postcard products. It is because it tends to be excellent in fatigue resistance.

  As described above, it is preferable to use epoxy (meth) acrylate or urethane (meth) acrylate alone or in combination of two types of epoxy (meth) acrylate and urethane (meth) acrylate. It is preferred to use (meth) acrylate alone.

  Examples of the epoxy (meth) acrylate include diglycidyl ether di (meth) acrylate of bisphenol A, a reaction product of a polyfunctional epoxy compound, (meth) acrylic acid and methyltetrahydrophthalic anhydride, and a polyfunctional epoxy compound. And a reaction product of (meth) acrylic acid, glycerin polyglycidyl ether poly (meth) acrylate, and the like. Among these, a viscosity of 100 to 1,000,000 mPa · s / 25 ° C. is particularly preferable, and 1,000 to 100,000 mPa · s / 25 ° C. is more preferable from the viewpoint of mechanical properties.

  On the other hand, as the urethane (meth) acrylate, for example, a urethane (meth) acrylate having a (meth) acryloyl group at both ends connected to a polyoxyalkylene segment or a saturated polyester segment via a urethane bond, or the like. can give. Among these, a viscosity of 100 to 100,000 mPa · s / 60 ° C is preferable, and 1,000 to 10,000 mPa · s / 60 ° C is more preferable from the viewpoint of mechanical properties.

  In the present invention, the viscosity means a viscosity measured using a B-type viscometer (product name: B-type viscometer; manufactured by Tokyo Keiki Co., Ltd.) under specific temperature conditions (for example, 25 ° C., 60 ° C., etc.).

<An ethylenically unsaturated compound (b2) other than (b1) having two ethylenically unsaturated groups>
The ethylenically unsaturated compound [polyfunctional compound (b2)] other than (b1) having two ethylenically unsaturated groups is an active energy ray-curable component (used in the composition for forming a pressure-sensitive adhesive coating film of the present invention ( It is used as a copolymerizable compound constituting B) and is a polyfunctional compound having two or more ethylenically unsaturated groups.

  Examples of the polyfunctional compound (b2) used in the present invention include polyfunctional (meth) acrylate monomers. Specifically, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (Meth) acrylate, dipropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, ethylene oxide modified bisphenol A type di (meth) acrylate , Propylene oxide modified bisphenol A di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, glycerin di (meth) Bifunctional (meth) acrylic compounds such as acrylate, pentaerythritol di (meth) acrylate, hydroxypivalic acid-modified neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate , Pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tri (meth) acryloyloxyethoxytrimethylolpropane, trimethylolpropane ethylene oxide modified tri (meth) acrylate, Trimethylolpropane propylene oxide modified tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, cap Lactone-modified dipentaerythritol penta (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate, trifunctional or more (meth) acrylic compounds such as and the like. Among these, 1,6-hexanediol di (meth) acrylate and trimethylolpropane tri (meth) acrylate are preferably used. These are used singly or in combination of two or more, particularly preferably in combination of two or more.

<An ethylenically unsaturated compound (b3) other than (b1) having one ethylenically unsaturated group>
The ethylenically unsaturated compound (b3) [monofunctional compound (b3)] other than (b1) having one ethylenically unsaturated group is an active energy ray curing used in the composition for forming a pressure-sensitive adhesive coating film of the present invention. The monofunctional compound having one ethylenically unsaturated group is used as a copolymerizable compound constituting the functional component (B). Examples of the monofunctional compound (b3) include (meth) acrylic acid alkyl ester (β-1) and other monofunctional compounds (β-2), and it is effective to use them as a monomer mixture obtained by mixing them. This is preferable.

  Examples of the (meth) acrylic acid alkyl ester (β-1) include (meth) acrylic acid alkyl esters having 1 to 20, preferably 2 to 18, and more preferably 4 to 10 carbon atoms in the alkyl group. It is done. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, tert-butyl (meth) acrylate, n -Octyl (meth) acrylate, iso-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, n-decyl (meth) acrylate, iso-decyl (meth) acrylate, etc. In particular, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and n-butyl (meth) acrylate are preferably used in terms of effects. One or more of these (meth) acrylic acid alkyl esters (β-1) are used.

  Examples of other monofunctional compounds (β-2) include (meth) acrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, fumaric acid, (meth) acrylamide-N-glycolic acid, and cinnamic acid. Michael adduct of (meth) acrylic acid (for example, acrylic acid dimer, methacrylic acid dimer, acrylic acid trimer, methacrylic acid trimer, acrylic acid tetramer, methacrylic acid tetramer, etc.), 2- (meth) acryloyloxyethyl dicarboxylic acid mono Esters (for example, 2-acryloyloxyethyl succinic acid monoester, 2-methacryloyloxyethyl succinic acid monoester, 2-acryloyloxyethyl phthalic acid monoester, 2-methacryloyloxyethyl phthalic acid monoester, 2-acryloyloxyethyl heter Carboxyl group-containing unsaturated compounds such as sahydrophthalic acid monoester, 2-methacryloyloxyethyl hexahydrophthalic acid monoester), 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-chloro-2 -Hydroxypropyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, diethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate, N-methylol (meth) acrylamide, etc. Hydroxyl group-containing unsaturated compounds, t-butylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, amino groups such as dimethylaminoethyl (meth) acrylate -Containing compounds, 2-acetoacetoxyethyl (meth) acrylate, acetoacetyl group-containing compounds such as allyl acetoacetate, 2-methoxyethyl (meth) acrylate, 3-methoxyethyl (meth) acrylate, methoxydiethylene glycol (meth) acrylate, etc. Allyl compounds such as alkoxy (poly) alkylene glycol mono (meth) acrylates, N- (meth) acrylamidomethyltrimethylammonium chloride, allyltrimethylammonium chloride, dimethylallyl vinyl ketone, N-vinylpyrrolidone, vinyl propionate, stearin (Β-1) or more such as vinyl monomers such as vinyl acid, vinyl chloride, vinylidene chloride, vinyl acetate, styrene, phenol ethylene oxide modified (meth) acrylate Of (meth) acrylic acid alkyl ester compound, etc. can be mentioned, one selected from these or two or more may be used.

  Particularly in applications where adhesive strength is required, in 100 parts of monofunctional compound (b3), as other monofunctional compound (β-2), a carboxyl group-containing unsaturated compound, preferably (meth) acrylic acid, crotonic acid, It is desirable to contain 1 to 20 parts of maleic acid, maleic anhydride, itaconic acid, fumaric acid, (meth) acrylamide-N-glycolic acid, cinnamic acid, particularly preferably (meth) acrylic acid.

Thus, examples of the active energy ray-curable component (B), you containing all three components of the above SL (b1) ~ (b3).

In the case of using the three components (b1) to (b3), the content ratio of each component is 5 to 20% by weight of the component (b1) with respect to the entire active energy ray-curable component (B). In particular, it is preferably 6 to 18% by weight, more preferably 7 to 16% by weight , and the component (b2) is 40 to 80% by weight, particularly 45 to 75% by weight, further 50 to 70% by weight. preferably Rukoto Oh, (b3) component is 10 to 40% by weight, in particular 13 to 35 wt%, more preferably to be set for 15 to 30 wt%.

  At least one of the epoxy (meth) acrylate and urethane (meth) acrylate (b1) imparts mechanical properties to the coating film and is a component that affects the surface hardness and flexibility. Therefore, if the content ratio of the component (b1) is too small, the stickiness of the coating film becomes strong, the adhesiveness is too strong at the time of peeling, paper breakage occurs, and the blocking resistance of the coated paper is insufficient. On the contrary, if the amount is too large, the coating film surface hardness becomes too high, so that the coating film tends to crack when bent. Moreover, adhesiveness also falls and the tendency for appropriate adhesive strength not to be obtained is also seen.

  The polyfunctional compound (b2) is a component having a role of a crosslinking agent, such as improving the reinforcing property. For this reason, if the content ratio of the component (b2) is too small, the cohesive strength of the resin is insufficient, the sticky feeling becomes strong and the glossiness is lowered, or the adhesiveness is too strong at the time of peeling, resulting in paper breakage. On the contrary, if the amount is too large, the cohesive force of the resin is increased and the adhesiveness tends to be weakened.

  Furthermore, the monofunctional compound (b3) is an acrylic rubber dispersant, which is polymerized by irradiation with active energy rays such as ultraviolet rays to control the cohesive force and glass transition temperature (Tg) of the resin. It is an ingredient. For this reason, if the content ratio of the component (b3) is too small, the content ratio of the component (b1) or the component (b2) having the role of a crosslinking agent is relatively increased, so that the cohesive strength of the resin becomes too high. On the other hand, if the amount is too large, the cohesive strength of the resin is insufficient, and the smoothness of the coating film surface tends to be lost during peeling.

<< Photopolymerization initiator (C) >>
The photopolymerization initiator (C) used in the present invention is not particularly limited as long as it generates radicals by the action of active energy rays such as light, and is an intramolecular self-cleavage photopolymerization initiator or hydrogen abstraction. A type of photoinitiator is used.

  Examples of the intramolecular self-cleaving photopolymerization initiator include 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1- ON, 1- (4-Isopropylenephenyl) -2-hydroxy-2-methylpropan-1-one, 1- (4-dodecylphenyl) -2-hydroxy-2-methylpropan-1-one, 4- ( 2-hydroxyethoxy) -phenyl (2-hydroxy-2-propyl) ketone, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one, Benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl Ether, benzoin isobutyl ether, benzyldimethyl ketal, α-acyloxime ester, acylphosphine oxide, methylphenylglyoxylate, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 4-benzoyl -4'-methyldiphenyl sulfide and the like. Among them, 2-hydroxy-2-methyl-1-phenylpropan-1-one and 1-hydroxy-cyclohexyl-phenyl-ketone are preferable.

Examples of the hydrogen abstraction type photopolymerization initiator include benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, 3,3′-dimethyl-4-methoxybenzophenone, 2,4. , 6-trimethylbenzophenone, 4-methylbenzophenone, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, camphorquinone, dibenzosuberone, 2-ethyl Anthraquinone, 3,3 ', 4,4'-tetra (t-butylperoxycarbonyl) benzophenone, benzyldimethyl ketal, 9,10-phenanthrenequinone, etc. are mentioned, among which benzophenone, methylbenzophenone, 2,4 6- trimethyl benzophenone are preferred.
These photopolymerization initiators (C) are used alone or in combination of two or more.

  If necessary, triethanolamine, triisopropanolamine, 4,4'-dimethylaminobenzophenone (Michler ketone), 4,4'-diethylaminobenzophenone, 2-dimethylamino can be used as an auxiliary for the photopolymerization initiator (C). Ethyl benzoic acid, ethyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate (n-butoxy), isoamyl 4-dimethylaminobenzoate, 2-dimethylhexyl 4-dimethylaminobenzoate, 2,4-diethylthio It is also effective to use xanthone, 2,4-diisopropylthioxanthone and the like together.

  Content of the said photoinitiator (C) is 10-30 parts with respect to 100 parts of said active energy ray hardening components (B), Preferably it is 13-27 parts, Especially 16-25 parts. It is preferable. If the content of the photopolymerization initiator is less than the above lower limit value, the polymerization is likely to vary. Conversely, if the content exceeds the above upper limit value, the adhesiveness does not occur and it is not suitable for practical use.

"Additive"
Further, in the present invention, other pressure-sensitive adhesives, urethane resins, rosins, rosin esters, hydrogenated rosin esters, phenol resins, aromatic modified terpene resins, aliphatic petroleum resins, alicyclic rings, as long as the effects of the present invention are not impaired. Tackifiers such as group petroleum resins, styrene resins, xylene resins, polymerization inhibitors, viscosity modifiers, leveling agents, waxes, antifoaming agents, anti-aging agents, stabilizers, colorants, fine particle fillers And the like, and compounds that cause coloration or discoloration by irradiation with ultraviolet rays or radiation can be added.

  By using the above component materials, the composition for forming an active energy ray-curable pressure-sensitive coating film of the present invention is obtained.

<< Composition for forming active energy ray-curable pressure-sensitive adhesive coating film >>
The composition for forming an active energy ray-curable pressure-bonded coating film of the present invention is substantially free of water, an aqueous solvent or an organic solvent, and contains a carboxyl group-containing acrylic polymer (A) and a photopolymerization initiator (C Further, other components added as required are dissolved or uniformly dispersed in the active energy ray-curable component (B). Such a composition for forming an active energy ray-curable pressure-bonded coating film includes a carboxyl group-containing acrylic polymer (A), an active energy ray-curable component (B), a photopolymerization initiator (C), and, if necessary, added. The other components to be prepared can be prepared by warming and mixing at room temperature (about 25 ° C. ± 10), and in some cases, from room temperature to 60 ° C.

  The viscosity of the obtained active energy ray-curable pressure-sensitive adhesive coating film-forming composition is preferably 100 to 500 mPa · s / 25 ° C. If the viscosity is too high, it tends to be difficult to apply uniformly, and conversely, if it is too low, the coating suitability deteriorates and it tends to be difficult to obtain a uniform coating film. Because.

  The obtained active energy ray-curable pressure-sensitive adhesive film-forming composition is formed on a whole surface or a predetermined portion of a base paper such as a printing sheet or postcard paper, and a gravure coater, flexo coater, air knife coater, bar coater. By applying an active energy ray to this, an adhesive layer that is appropriately cured is obtained. And the adhesion | attachment which has peelability is attained by superposing | stacking the said hardening adhesive layers on each other, for example, making it press-fit under a predetermined pressure with a pressure roller etc.

  Examples of the base paper to be coated with the coating film forming composition of the present invention include high-quality paper, medium-quality paper, rough paper, cotton paper, art paper, coated paper, lightweight coated paper, and plastic laminate. Examples thereof include paper, cloth, plastic laminate cloth, plastic film, and metal foil.

  As described above, in the case of overlaying and pressure bonding after irradiation with active energy rays, it is more preferable to irradiate active energy rays in an inert gas atmosphere in order to eliminate polymerization inhibition factors due to oxygen during irradiation with active energy rays. It is also possible to balance the physical properties by adjusting the irradiation conditions in consideration of the polymerization inhibition factor due to oxygen.

《Active energy ray》
In the above, as the active energy ray, in addition to electromagnetic waves such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays, infrared rays, electromagnetic waves such as X-rays and γ rays, electron beams, proton rays, neutron rays, etc. can be used. Curing by ultraviolet irradiation is advantageous because of the availability of the irradiation device and the price.

  For ultraviolet irradiation, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, a chemical lamp, an electrodeless discharge lamp, or the like that emits light in a wavelength range of 150 to 450 nm can be used.

In the present invention, the exposure dose of the actinic energy ray is preferably at 500 mJ / cm ² or more, particularly 1000 mJ / cm ² or more, and further preferably not 1500 mJ / cm ² or more. When this irradiation amount is too low, there is a tendency that the polymerization by active energy ray irradiation tends to vary. The upper limit of the irradiation dose is usually 10,000 mJ / cm ² . This is because if the irradiation amount is too large, there is a tendency that it is not practical due to the relationship between the apparatus and the cost.

  Further, the thickness of the adhesive layer obtained by coating is not limited in general because requirements vary depending on the application, but is preferably 5 to 200 μm, and more preferably 10 to 150 μm. This is because if the thickness of the adhesive layer is too thin, the adhesive properties tend to be difficult to stabilize, and conversely, if it is too thick, adhesive residue tends to occur.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist.
In the examples, “parts” and “%” mean weight basis unless otherwise specified.

<Preparation of acrylic polymer>
[Production Example 1: Component A (for Examples)]
In a polymerization apparatus equipped with a stirrer, a thermometer, and a condenser, 250 parts of deionized water was added and stirred, and 0.6 part of polyvinyl alcohol was added and dissolved as a dispersion stabilizer. Thereafter, while stirring this, 2.5 parts of acrylic acid, 10 parts of acrylonitrile, 77.5 parts of n-butyl acrylate, 10 parts of methyl methacrylate, 0.5 part of n-dodecyl mercaptan, and azobisiso 0.4 part of butyronitrile was added. Next, the contents were heated to 75 ° C. and reacted for 3 hours while maintaining the reaction temperature of 75 ° C. Thereafter, the temperature was raised to 90 ° C., and this temperature was maintained for 1 hour to complete the reaction. The reaction product was filtered and washed with a filter cloth having a mesh size of 10 μm and dried with a circulating hot air dryer at 50 ° C. to obtain a carboxyl group-containing acrylic polymer (component A).
The obtained carboxyl group-containing acrylic polymer had a weight average molecular weight (Mw) of 80,000 and a glass transition temperature of −50 ° C.

[Production Example 2: Comparative Example]
A four-necked round bottom flask was equipped with a reflux condenser, stirrer, dropping funnel and thermometer, charged with 88 parts of n-butyl acrylate, 7 parts of acrylonitrile, 5 parts of 2-hydroxyethyl methacrylate, and 80 parts of ethyl acetate, and heated. After the start of reflux, 0.06 part of azobisisobutyronitrile was added as a polymerization initiator, reacted for 2 hours at the reflux temperature of ethyl acetate, and 0.07 part of azobisisobutyronitrile was dissolved in 5 parts of toluene. And further reacted at reflux temperature for 5 hours. Thereafter, this reaction product was dried at 70 ° C. for 12 hours using a dryer to obtain an acrylic polymer for a comparative example containing no carboxyl group.
The obtained acrylic polymer had a weight average molecular weight (Mw) of 400,000 and a glass transition temperature of -40 ° C.

  Using each acrylic polymer obtained in the above production example, each active energy ray-curable pressure-sensitive coating film-forming composition was produced according to the following examples and comparative examples.

[Example 1]
13 parts of the carboxyl group-containing acrylic polymer obtained in Production Example 1, 13 parts of epoxy acrylate (trade name: “CN-116”; manufactured by Sartomer) as the component (b1), and trimethylolpropane as the polyfunctional compound (b2) 22 parts of triacrylate, 40 parts of 1,6-hexanediol diacrylate, 11 parts of n-butyl acrylate as monofunctional compound (b3), 2-hydroxy-3-phenoxypropyl acrylate (trade name: “Aronix M-5700”; 14 parts of Toa Gosei Co., Ltd. was placed in a container equipped with a stirrer and stirred and mixed for 24 hours to dissolve. The viscosity of this solution was 150 mPa · s / 25 ° C.

  In this solution, 16 parts of 1-hydroxy-cyclohexyl-phenyl-ketone (trade name “Irgacure 184”; manufactured by Ciba Specialty Chemicals) as a photopolymerization initiator (C), 2-methyl-1- (4-methylthiophenyl) ) -2-morpholinopropan-1-one (trade name: “Irgacure 907”; manufactured by Ciba Specialty Chemicals) was mixed to obtain a composition for forming an active energy ray-curable pressure-sensitive adhesive coating film. .

[ Reference Example 1 ]
14 parts of the carboxyl group-containing acrylic polymer obtained in Production Example 1, 26 parts of trimethylolpropane triacrylate as the polyfunctional compound (b2), 43 parts of 1,6-hexanediol diacrylate, and n as the monofunctional compound (b3) -Active energy ray-curable type in the same manner as in Example 1 except that 14 parts of butyl acrylate and 17 parts of 2-hydroxy-3-phenoxypropyl acrylate (trade name: “Aronix M-5700”; manufactured by Toagosei Co., Ltd.) are used. A composition for forming a pressure-bonded coating film was obtained.

Example 3
14 parts of carboxyl group-containing acrylic polymer obtained in Production Example 1, 14 parts of epoxy acrylate (trade name: “CN-116”; manufactured by Sartomer) as component (b1), 63 parts of 1,6-hexanediol diacrylate Example 1 except that 10 parts of n-butyl acrylate and 13 parts of 2-hydroxy-3-phenoxypropyl acrylate (trade name: “Aronix M-5700”; manufactured by Toagosei Co., Ltd.) were used as the monofunctional compound (b3). In the same manner as above, an active energy ray-curable pressure-sensitive adhesive coating film-forming composition was obtained.

[Comparative Example 1]
Active energy ray curing is carried out in the same manner as in Example 1 except that the photopolymerization initiator is 6 parts of 1-hydroxy-cyclohexyl-phenyl-ketone (trade name “Irgacure 184”; manufactured by Ciba Specialty Chemicals). A composition for forming a pressure-bonded coating film was obtained.

[Comparative Example 2]
Example 1 except that the photopolymerization initiator was 6 parts 2-hydroxy-2-methyl-phenyl-propan-1-one (trade name “D-1173”; manufactured by Ciba Specialty Chemicals) Thus, an active energy ray-curable pressure-sensitive adhesive film-forming composition was obtained.

[Comparative Example 3]
The photopolymerization initiator was changed to 6 parts of 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one (trade name: “Irgacure 907”; manufactured by Ciba Specialty Chemicals). In the same manner as in Example 1, a composition for forming an active energy ray-curable pressure-sensitive adhesive coating film was obtained.

[Comparative Example 4]
An active energy ray-curable pressure-sensitive adhesive film-forming composition was obtained in the same manner as in Example 1, except that the acrylic polymer for Comparative Example obtained in Production Example 2 was used. In addition, the viscosity of the solution before adding a photoinitiator was 1300 mPa * s / 25 degreeC.

  Table 1 below shows the blending ratios of the above component materials used in Examples and Comparative Examples.

Using the active energy ray-curable pressure-sensitive adhesive coating film-forming composition obtained in each of the above Examples , Reference Examples and Comparative Examples, a peelable adhesive processed paper was prepared by the following method.
^On the coated paper having a weight of 110 g / m ² , the active energy ray-curable pressure-sensitive adhesive film-forming composition obtained in each example , reference example and comparative example was applied at a rate of 7 g / m ² with a wire bar, An adhesive layer was formed by curing by ultraviolet irradiation to obtain each peelable adhesive processed paper. The ultraviolet irradiation conditions are a high-pressure mercury lamp, an irradiation intensity of about 200 W / m ² , an integrated illuminance of 60 mJ / m ² , and a lamp height of 18 cm.

  Using each of the obtained peelable adhesive-treated papers, the coatability and curability were evaluated.

<Coating properties>
The coated surface of the peelable adhesive processed paper was observed, and the coated state was judged according to the following criteria.
○: The entire surface is evenly coated and glossy.
Δ: Slightly disturbed coating surface is observed, but there is no practical problem.
X: The mixing property of the composition is poor, or because of high viscosity, the coated surface is disturbed and gaps are scattered.

<Curing property>
The stickiness and hardness of the coated surface of the peelable adhesive processed paper were confirmed, and the cured state of the adhesive layer was determined according to the following criteria.
○: There is no stickiness and the curing is sufficiently completed.
(Triangle | delta): Although it has hardened almost, there exists some sticky part.
X: There is much stickiness, it peels off when scratched lightly, and it is in a state of poor curing.

  Next, the peelable adhesive-treated paper is cut into a width of 25 mm and a length of 100 mm, and the coated surfaces are combined with each other in two layers, and are pressure-bonded using a laminator with a pressure of 0.2 MPa, and a sample having a width of 25 mm ( Pressure temporary adhesive paper).

  The adhesiveness was evaluated using each of the obtained pressure temporary adhesive papers.

<Adhesiveness>
The pressure temporary adhesive paper was bent, and the presence or absence of adhesion failure such as peeling of the adhesion surface and floating was confirmed, and the adhesion state was judged according to the following criteria.
(Double-circle): It adhere | attaches completely and even if it bends, peeling of an adhesion part does not arise.
○: Almost adhered and can be used sufficiently for the application of the present invention.
Δ: Adhesion is temporary, but it is weak, and depending on the paper quality, if it is bent, the adhesion surface may be lifted away.
X: Adhesion is weak or not adhered at all.

  Furthermore, peelability was evaluated by the following method using the pressure temporary adhesive paper.

Using a universal measuring machine (trade name “Autograph”; manufactured by Shimadzu Corporation) on a pressure temporary adhesive paper having a width of 25 mm under the measurement conditions of a peeling speed of 300 mm / min, 23 ° C., and a relative humidity of 50%, a T type A peel test was performed.
<Peelability>
The peeling state in the T-type peeling test was determined according to the following criteria.
○: The paper peels without tearing.
Δ: The paper peels without tearing, but the peel strength is strong, and depending on the paper quality, cracks may appear on the surface of the coating film.
X: Adhered, and if it is peeled off, the paper is torn.
-: Not determined from the beginning because it is not bonded.

  Table 2 below shows the evaluation results of the coating properties, curability, adhesiveness, and peelability obtained above.

From the above results, the peelable adhesive processed paper obtained in Example 1 was excellent in coating property, curability, adhesiveness, and peelability, and was highly practical . Also, although the embodiment 3 in which not only one kind of multifunctional compound (b2) blended real施例3, coating properties, a good adhesion, even in other physical properties such as releasability It was practical. Moreover, in these Examples, the drying process at the time of coating was unnecessary, and the surface gloss which was excellent in the printing surface was seen.

  On the other hand, Comparative Examples 1 to 3, which are contents of a general photopolymerization initiator, cannot be said to have sufficient adhesion due to poor curing. Moreover, since the comparative example 4 using the acrylic polymer which does not contain a carboxyl group has bad mixability of the composition for pressure-bonding coating film formation, is inferior in coating property, and adhesiveness is too high, if it tries to peel off The paper was torn.

  The composition for forming an active energy ray-curable pressure-bonded coating film of the present invention is used as an adhesive used in a postcard system having a confidentiality instead of a sealed letter for the purpose of reducing postage costs, printing information and automating the creation of a notice. It is useful and can also be used as a double-sided tape or an adhesive tape by coating on a base material sheet such as a nonwoven fabric or a foam base material.

Claims (6)

The carboxyl group-containing acrylic polymer (A) contains the following (b1) to (b3), and the content ratio of the following (b1) to (b3) is relative to the whole active energy ray-curable component (B). An active energy ray-curable component (B) containing 5 to 20% by weight of (b1), 40 to 80% by weight of (b2), and 10 to 40% by weight of (b3 ), and a photopolymerization initiator (C) The composition for forming an active energy ray-curable pressure-bonded coating film, wherein the content of the carboxyl group-containing acrylic polymer (A) is 100 parts by weight of the active energy ray-curable component (B). 5 to 45 parts by weight, and the content of the photopolymerization initiator (C) is 10 to 30 parts by weight with respect to 100 parts by weight of the active energy ray-curable component (B). For energy beam curable pressure-sensitive adhesive coatings Narubutsu.
(B1) At least one of epoxy (meth) acrylate and urethane (meth) acrylate.
(B2) An ethylenically unsaturated compound other than (b1) having two or more ethylenically unsaturated groups. (B3) An ethylenically unsaturated compound other than (b1) having one ethylenically unsaturated group.   The composition for forming an active energy ray-curable pressure-bonded coating film according to claim 1, wherein the carboxyl group-containing acrylic polymer (A) has a weight average molecular weight of 100,000 or less.   3. The composition for forming an active energy ray-curable pressure-bonded coating film according to claim 1, wherein the carboxyl group-containing acrylic polymer (A) has a glass transition temperature in the range of −60 to 20 ° C. 3. The active energy ray-curable ingredient (B) is (b2), the active energy ray-curable bonding coating forming composition according to any one of claims 1 to 3, wherein Rukoto such two or more Thing . Content of a photoinitiator (C) is 16-30 weight part with respect to 100 weight part of said active energy ray hardening components (B) , The any one of Claims 1-4 characterized by the above-mentioned. The composition for active energy ray-curable pressure-sensitive adhesive coating film formation described in 1 . The active energy ray-curable pressure-sensitive adhesive film-forming composition according to any one of claims 1 to 5 is coated on a paper surface and cured with an active energy ray. paper.