JP2006299017A - Uv ray-curable adhesive composition and adhesive sheet using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a UV ray-curable adhesive composition that has excellent hot-melt applicability, shows excellent adhesive property even when it is held under a high-temperature atmosphere and has reduced smell. <P>SOLUTION: This composition includes (A) a vinyl copolymer having a Tg of less than -5°C and a Mw of 50,000 to 350,000 and (A) the copolymer is constituted with the following (a) to (d) monomers wherein (a) 10 to 99 mass% of an acrylic acid ester bearing a 1-4C hydrocarbon substituent, (b) 1 to 13 mass% of an α,β-unsaturated carboxylic acid, (c) 0.01 to 10 mass% of a benzophenone derivative bearing a (meth)acryloyloxy group or a (meth)acryloyloxyalkylenoxy group on the 2 or 4 position and (d) 0 to 88.99 mass% of the other copolymerizable vinyl monomers where (a)+(b)+(c)+(d)=100 mass%. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pressure-sensitive adhesive composition used for pressure-sensitive adhesive tapes and pressure-sensitive adhesive sheet-like materials such as pressure-sensitive adhesive labels, and more specifically UV curable hot-melt pressure-sensitive adhesive that can be applied to a substrate such as a tape or a label. It is related with an agent composition.

  In recent years, due to increasing interest in the environment, adhesive compositions that do not use any organic solvent have attracted attention. For example, Patent Document 1 (JP 59-75975 A) and Patent Document 2 (JP 60-23469 A). And the like have proposed an acrylic hot-melt pressure-sensitive adhesive composition characterized by applying a heat-melted resin onto a substrate. However, the pressure-sensitive adhesive tapes using these conventional acrylic hot-melt pressure-sensitive adhesive compositions have poor adhesive properties such as adhesive strength, holding power, tack, etc., and in particular, insufficient holding power in a high-temperature atmosphere. was there.

  In order to improve the above-mentioned drawbacks, for example, Patent Document 3 (JP-A-2-276879), Patent Document 4 (JP-A-3-1155481), Patent Document 5 (JP-A-3-111981), Patent In Document 6 (Japanese Patent Laid-Open No. 3-119082), Patent Document 7 (Japanese Patent Laid-Open No. 3-220275), etc., the acrylic pressure-sensitive adhesive composition that has been hot-melt coated can be crosslinked by irradiation with active energy rays. Proposed. Similarly, Patent Document 8 (Japanese Patent Laid-Open No. 62-284651) reports a pressure-sensitive adhesive for skin obtained by copolymerizing a copolymerizable photoinitiator.

  However, in any of these publications, these pressure-sensitive adhesive compositions contain a compound having two or more unsaturated double bonds as a constituent component. When the pressure-sensitive adhesive composition is heat-treated during the coating process of the composition on the base material, the pressure-sensitive adhesive composition is likely to be thermally polymerized, resulting in unstable hot melt coating properties, residual monomer components and their ultraviolet rays. There were problems such as the odor of the photodegradation product upon irradiation and the odor due to thermal decomposition of the ester compound of the copolymer side chain.

  In order to improve the above problems, it has been proposed to add an antioxidant or a fragrance as an additive in the pressure-sensitive adhesive composition, but if the pressure-sensitive adhesive composition is still kept for several hours at the coating temperature, In addition, it has gelled, and there is a problem that it is easy to produce and color degradable organisms that cause odor.

  In order to solve the above problems, for example, in Patent Document 9 (Japanese Patent Laid-Open No. 2-18484), Patent Document 10 (Japanese Patent Laid-Open No. 8-60127), etc., an unsaturated double bond is provided. There have been proposed a melt adhesive composition and a photocationic pressure-sensitive adhesive composition that can be cross-linked by irradiation with ultraviolet rays in the air without using a compound. Further, for example, in Patent Document 11 (Japanese Patent Laid-Open No. 2-305847) and the like, an ultraviolet curable composition containing an acrylic copolymer using a specific photopolymerization initiator has been proposed, and thermal stability is proposed. It is characterized by superiority.

  The melt adhesive composition proposed in Patent Document 9 is described as being crosslinkable by ultraviolet irradiation in the air by introducing a specific copolymerizable monomer and a photopolymerization initiator. There is a problem that the heat resistance of the pressure-sensitive adhesive sheet to be obtained is insufficient, and if the heat resistance is sufficient, the adhesive strength or tack is not sufficient. Further, the photocationic pressure-sensitive adhesive composition proposed in Patent Document 10 may lack transparency when the compatibility between the acrylic copolymer and the onium salt that is a photopolymerization catalyst is deteriorated. Furthermore, since it has a specific odor caused by the photodegradation product of the photopolymerization catalyst, further improvement is desired.

  In addition, the ultraviolet curable composition proposed in Patent Document 11 has low activity against ultraviolet rays, and a large amount of ultraviolet rays is required for curing, so that the production cost of an adhesive tape or the like tends to increase. There was a problem that the substrate was easily damaged.

  Patent Document 8 described above relating to a pressure-sensitive adhesive composition for skin uses a copolymerizable monoethylenically unsaturated aromatic ketone monomer (PX monomer) containing a copolymerizable benzophenone used in the present invention. It is possible to control the creep compliance of the adhesive, but there is no specific description of the UV curable hot melt adhesive, and the adhesive properties will be maintained if the described composition is held for a certain period of time in a high temperature atmosphere. There was a problem of deterioration and odor generation.

JP 59-75975 JP 60-23469 A JP-A-2-276879 Japanese Patent Application Laid-Open No. 3-1155481 Japanese Patent Laid-Open No. 3-119081 Japanese Patent Laid-Open No. 3-119022 JP-A-3-220275 JP-A-62-284651 Japanese Patent Laid-Open No. 2-18484 JP-A-8-60127 JP-A-2-305847

  The present invention is excellent in hot melt coating properties, and can be cured even with a lower ultraviolet light amount than in the past, and the resulting pressure sensitive adhesive sheet has good adhesive properties such as adhesive strength, holding power, and tack, An object of the present invention is to provide an ultraviolet curable hot-melt pressure-sensitive adhesive composition that has excellent adhesive properties even when held for a certain period of time in a high-temperature atmosphere and has a low content of compounds that can cause odor.

This invention which solves the said subject is an ultraviolet curable hot-melt adhesive composition containing the vinyl copolymer (A) whose glass transition temperature is -5 degrees C or less and whose weight average molecular weight is 50000-350,000, An ultraviolet curable hot melt pressure-sensitive adhesive composition, wherein the vinyl copolymer (A) is obtained by polymerizing monomer components (a) to (d) below: It is characterized by using.
(A) 10 to 99% by mass of an acrylate polymerizable monomer having a hydrocarbon substituent having 1 to 4 carbon atoms,
(B) 1 to 13% by mass of an α, β-unsaturated carboxylic acid polymerizable monomer,
(C) 0.01 to 10% by mass of at least one selected from copolymerizable benzophenones represented by the following general formula (I) or (II):
(D) 0 to 88.9 mass% of other copolymerizable vinyl monomers
(However, the total of (a) + (b) + (c) + (d) is 100% by mass)

(In the formula, R and R ′ each independently represent an alkyl group, a carboxyl group, or a halogen atom, n represents an integer of 0 to 5, m represents an integer of 0 to 4, and X represents (meta) Represents an acryloyloxy group or a (meth) acryloyloxyalkyleneoxy group.)

  The ultraviolet curable hot-melt pressure-sensitive adhesive composition of the present invention is excellent in adhesive properties such as holding power, has excellent adhesive properties even when held for a certain period of time in a high-temperature atmosphere, and reduces the content of compounds that can cause odor. This is a very industrially useful product.

Details of the present invention will be described below.
A pressure-sensitive adhesive label and the like according to a preferred embodiment of the ultraviolet curable hot-melt pressure-sensitive adhesive composition of the present invention will be described with reference to the drawings. FIG. 1 shows a layer structure of a label according to the first embodiment of the present invention, wherein 1 is a base film, 2 is a printing ink layer, 3 is an adhesive layer, and 4 is a separator.

  The base film 1 is, for example, paper, polyethylene terephthalate (PET), polystyrene (PS), or expanded polypropylene (OPP), and is attached to a transparent PET bottle, glass bottle, paper, or the like. The printing ink layer 2 is printed with a so-called reverse printing pattern so that the printed pattern can be seen through the base film 1.

  In addition, by making the base film 1 a colored and opaque material, printing on the front side of the base film 1 and printing on the back side of the base film 1 to form the adhesive layer 3, a glass bottle and The printed pattern on the back side may be seen through the filled liquid. It is also possible to print a pattern that becomes an opaque background on the background of the pattern, and to perform regular printing that is not reverse printing so that the opaque print can be seen through the PET bottle and the filled liquid. good.

  The pressure-sensitive adhesive layer 3 is mainly composed of the ultraviolet curable hot-melt pressure-sensitive adhesive composition of the present invention.

<< Vinyl copolymer (A) >>
The vinyl copolymer (A) used in the ultraviolet curable hot-melt pressure-sensitive adhesive composition of the present invention comprises (a) a hydrocarbon-substituted alkyl acrylate ester polymerizable monomer having 1 to 4 carbon atoms. ~ 99% by mass, (b) α, β-unsaturated carboxylic acid polymerizable monomer 1 to 13% by mass, (c) selected from copolymerizable benzophenones represented by the general formula (I) or (II) 0.01 to 10% by mass of at least one selected from the above, (d) 0 to 88.9% by mass of other copolymerizable vinyl monomers (provided that (a) + (b) + (c) + ( The sum of d) is 100% by mass) and is obtained by polymerizing these.

<(A) component>
Examples of the component (a) of the present invention include methyl acrylate, ethyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate and the like. Particularly preferred is n-butyl acrylate, which tends to be the least prone to decrease in the amount. These may be used alone or in combination of two or more as required.

<(B) component>
Examples of the component (b) of the present invention include acrylic acid, methacrylic acid, itaconic acid, fumaric acid and the like. These can be used alone or in combination of two or more as required. The amount of use is 1 to 13% by mass, but if it is 2.1% by mass or more, the adhesive strength can be further improved, and if it is 13% by mass or less, the coating viscosity can be made good. it can. More preferably, it is 2.5-8 mass%.

<(C) component>
In the copolymerizable benzophenones of the general formula (I) or (II) of the component (c) of the present invention, R and R ′ are each independently an alkyl group such as a methyl group, an ethyl group, or a propyl group. , A carboxyl group, or a halogen atom such as fluorine, chlorine, bromine or iodine, and X is a (meth) acryloyloxyalkyleneoxy group such as an acryloyloxy group, a methacryloyloxy group, or an acryloyloxyethyleneoxy group. As the component (c), one type of compound may be used, or two or more types may be used in combination. The component (c) of the present invention is preferably a compound represented by the general formula (II), and 4-methacryloyloxybenzophenone is particularly preferable. The amount used is in the range of 0.01 to 10% by mass, and more preferably in the range of 0.05 to 3% by mass. If it is this range, performances, such as holding power, adhesive strength, and tack, will all improve and it will become a well-balanced sample.

  The copolymerizable benzophenone represented by the general formula (I) or (II) as the component (c) can be produced by the method described in Patent Document 8. For example, it can be obtained by a method of reacting 4-hydroxybenzophenone and (meth) acryloyl halide in the presence of a base.

<(D) component>
The component (d) of the present invention is not particularly limited as long as it is a vinyl monomer copolymerizable with the components (a), (b), and (c), but methyl methacrylate, ethyl methacrylate, Methacrylic acid esters having a hydrocarbon substituent having 1 to 4 carbon atoms such as n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, amyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meta ) Acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate , Tridecyl (meth) acrylate, (Meth) acrylic acid esters having a hydrocarbon group with 5 or more carbon atoms, such as tealyl (meth) acrylate, cyclohexyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, vinyl acetate, chloride Contains vinyl monomers such as vinyl, acrylamide, N-alkoxy substituted acrylamide, and styrene, and hydroxyl groups such as 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate (Meth) acrylic acid esters can be mentioned. (D) A component is an arbitrary component and can be used in 0-88.999 mass%. The component (d) can be used for adjusting the adhesive strength. However, when the amount of the component (d) is increased, the adhesive property tends to be lowered when held for a certain period of time in a high temperature atmosphere. Irradiation may cause degradation of the polymer side chain ester or residual monomer ester to produce a low-molecular decomposition product that can cause odor, and is preferably used at 50% by mass or less, more preferably 30% by mass or less. Is desirable.

<Acid value>
The vinyl copolymer (A) has an acid value in the range of 4 to 100 mgKOH / g, preferably in the range of 8 to 90 mgKOH / g. When it exceeds 4 mgKOH / g, the adhesive force, tackiness, and holding power are improved, and when it is less than 100 mgKOH / g, the resin viscosity can be lowered, so that the coating property is improved. More preferably, it is the range of 16-80 mgKOH / g.

<Molecular weight>
The vinyl copolymer (A) has a weight average molecular weight in the range of 50,000 to 350,000, preferably 60000 to 300,000 from the viewpoint of film forming property. When it exceeds 50000, the holding force and the adhesive force are improved, and when it is less than 350,000, the coating property is improved.

<Glass transition temperature>
The glass transition temperature of the vinyl copolymer (A) of the present invention is −5 ° C. or lower, more preferably −20 ° C. or lower. The pressure-sensitive adhesive obtained using a vinyl copolymer having a glass transition temperature higher than −5 ° C. is inferior in tackiness. The “glass transition temperature” referred to here is the glass transition temperature of the vinyl polymer (A) before UV curing, and is a value obtained from the FOX formula, as will be described later.

<Polymerization method>
As the polymerization method of the vinyl copolymer (A) of the present invention, any of solution polymerization method, suspension polymerization method, emulsion polymerization method and the like can be used, but the solution polymerization method is particularly preferable. As the solvent used in the solution polymerization, commonly used solvents such as xylene, ethyl acetate, n-butanol, methyl ethyl ketone, and toluene can be used. The vinyl copolymer (A) solution obtained by the solution polymerization method is used after removing the solvent for hot melt coating.

<Polymerization initiator>
When polymerizing the vinyl copolymer (A) of the present invention, it is preferable to use a radical polymerization initiator. Examples of radical polymerization initiators include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), and the like. Azo-based oil-soluble initiators, oil-soluble peroxides such as benzoyl peroxide and lauroyl peroxide, and aqueous peroxides such as potassium persulfate and ammonium persulfate. These polymerization initiators can be used alone or in combination of two or more.

<Chain transfer agent>
At the time of polymerization, a known chain transfer agent may be used as necessary in order to control the molecular weight. Examples of the chain transfer agent include n-dodecyl mercaptan, n-octyl mercaptan, 2-ethylhexyl thioglycolic acid ester, thiophenol, α-methylstyrene dimer, and the like. These chain transfer agents can be used alone or in combination of two or more.

<Polymerization conditions>
When the vinyl copolymer (A) is produced, the reaction temperature is preferably in the range of 30 ° C to 140 ° C. The reaction time is about 1 to 12 hours. By producing in this range, the polymerization stability becomes good.

<Desolvent>
Solvent removal of the vinyl copolymer (A) solution obtained by the solution polymerization method can be performed at a temperature of 50 ° C. to 160 ° C. under a high vacuum. The solvent removal device is not particularly limited, but a method of removing the solvent directly from the polymerization device at high temperature and high vacuum or a devolatilization device that removes the solvent while concentrating the resin solution at high temperature and high vacuum are used. Method.

<Adhesive sheet>
<Base material>
The base material 1 shown in FIGS. 1 and 2 used for an adhesive sheet-like material such as an adhesive label of the present invention is not particularly limited as long as it can be printed. Examples of the substrate 1 when the pressure-sensitive adhesive label is a transparent pressure-sensitive adhesive label include polyethylene terephthalate (PET), polystyrene (PS), stretched polypropylene (OPP), and the like. Further, the thickness, size, shape, etc. of the substrate are also selected depending on the use of the pressure-sensitive adhesive label, and are not particularly limited. The printed layer 2 of the pressure-sensitive adhesive label of the present invention is a layer in which a pattern, characters, etc. are printed with ink or the like. 1 and 2, when the base material 1 is a transparent material such as polystyrene, the printed pattern is normal when viewed through the base material 1 from the base material 1 side. It is desirable to print the pattern in the so-called reverse printing.

  Moreover, the base material 1 shown in FIG. 1 was made into a colored and opaque material, printing was performed on the back surface side of the base material 1 to form the print layer 2, and the adhesive layer 3 was formed on the print layer 2. In this case, it is desirable to perform printing so that the printed pattern of the printing layer 2 can be normally viewed when viewed through the pressure-sensitive adhesive 3 from the pressure-sensitive adhesive layer 3 side. Further, when the substrate 1 is a transparent material, the background of the pattern of the printing layer 2 is opaque, and the background is on the substrate 1 side of the printing layer 2, the adhesive layer 3 is viewed through the adhesive 3. When printing, it is desirable to perform printing so that the printed pattern of the printing layer 2 can be seen normally. Further, when the substrate 1 is a transparent material, the background of the pattern of the printed layer 2 is opaque, and the background is on the adhesive layer 3 side of the printed layer 2, the substrate 1 is viewed through the substrate 1 side. When printing, it is desirable to perform printing so that the printed pattern of the printing layer 2 can be seen normally.

<Separator>
The separator 4 is a film or sheet that can be easily peeled off even if an adhesive film is attached. An example of a material used for the separator 4 is a polyethylene terephthalate (PET) base film coated with a silicon release agent, which can be easily peeled off even if the adhesive used in the present invention is adhered. If it is, it will not specifically limit.

<Example of layer structure of adhesive label>
FIG. 2 shows an example of the layer structure of an adhesive label having a concealing layer. Printing is performed on one side of the substrate 1 to form the printing layer 2a, and the concealing layer 5 which is an opaque layer is formed thereon. Next, printing is performed on the other surface of the concealing layer 5 to form the printing layer 2b, and an adhesive is applied thereon to form the adhesive layer 3. Then, the separator 4 is bonded to the pressure-sensitive adhesive layer 3. The masking layer 5 is an opaque layer and serves to shield the two print layers from overlapping. By doing in this way, the printed picture different from the base material 1 side and the adhesive layer 3 side can be seen. The material and thickness of the masking layer 5 are not particularly limited as long as they are opaque and can be shielded so that the two print layers do not overlap. Examples of the concealing layer 5 include a printing layer having an opaque background, a metal vapor deposition film layer, and an opaque resin film layer.

<Label manufacturing method>
Next, the manufacturing method of the adhesive label of this invention is demonstrated. FIG. 3 shows an example of an apparatus for producing the adhesive label according to the present invention. This adhesive label manufacturing apparatus 10 includes a substrate film roll 11 that supplies the substrate 1, a printing machine 12, a coating machine 13, an ultraviolet lamp 14, a separator roll 15 that supplies a separator 4, a cutter 16, and an adhesive label film roll 17. It is configured.

  In the manufacturing method using the apparatus shown in FIG. 3, first, the transparent substrate 1 is sent out from the substrate film roll 11 and printed by the printer 12. At this time, the reverse printing is performed so that the printing looks normal when viewed from the substrate 1 side. Next, the pressure-sensitive adhesive is applied to the printing surface side by the coating machine 13 to form the pressure-sensitive adhesive layer 3. Subsequently, the pressure-sensitive adhesive layer 3 is cured by being irradiated with ultraviolet rays using an ultraviolet lamp 14. The film in which the pressure-sensitive adhesive is cured becomes a transparent film. The separator 4 is supplied from the separator roll 15 to the adhesive layer 3 of the transparent film and bonded. Then, only the transparent film side is punched into a predetermined label shape by the half-cut cutter 16. After punching, an unnecessary portion of the transparent film is peeled off from the separator 4 and wound on an adhesive label film roll 17 to obtain an adhesive label sheet 17 in which adhesive labels are arranged on the separator 4. The manufacturing method of this pressure-sensitive adhesive label is not limited to the above-described manufacturing method. For example, the pressure-sensitive adhesive label may be used for application of a pressure-sensitive adhesive using a transparent base film printed in reverse printing in advance, or the pressure-sensitive adhesive layer may be previously formed. A separator that has been coated and UV cured may also be used.

  In FIG. 4, an example of the apparatus which manufactures the adhesive label which has the concealing layer of this invention shown in FIG. 2 is shown. This adhesive label manufacturing apparatus 20a is composed of a base film roll 11, a printing machine 12, a coating machine 13, an ultraviolet lamp 14, a separator roll 15, a cutter 16, an adhesive label film roll 17, and a masking layer forming printing machine 18. Yes. First, the base material 1 is supplied from the base material film roll 11, and printing is performed thereon by the printing machine 12 to form the printing layer 2a. The masking layer forming printing machine 18 performs printing with an opaque background to form the masking layer 5 on the printing layer 2a. Next, printing is performed on the surface of the masking layer 5 opposite to the surface in contact with the printing layer 2a to form the printing layer 2b. Then, the pressure-sensitive adhesive is applied onto the printing layer 2 b by the coating machine 13 to form the pressure-sensitive adhesive layer 3, and is cured by irradiating with ultraviolet rays using the ultraviolet lamp 14. The separator 4 is supplied from the separator roll 15 to the pressure-sensitive adhesive layer 3 and bonded to the pressure-sensitive adhesive layer 3.

  From the base material 1 side of this film, a half-cut cutter 16 is punched into a predetermined label shape so as not to punch out only the separator. After punching, an unnecessary part of the film is peeled off from the separator and wound on an adhesive label sheet roll 17 to obtain an adhesive label sheet in which adhesive labels are arranged on the separator. The method for producing this pressure-sensitive adhesive label is not limited to the above-mentioned production method, and for example, it may be used for forming a concealing layer and applying a pressure-sensitive adhesive using a substrate on which both sides have been printed in advance. It is also possible to use a separator that has been previously coated and UV cured.

  FIG. 5 shows another example of an apparatus for producing an adhesive label having the concealing layer of the present invention shown in FIG. The pressure-sensitive adhesive label manufacturing apparatus 20 b includes a base film roll 11, a printing machine 12, a coating machine 13, an ultraviolet lamp 14, a separator roll 15, a cutter 16, a pressure-sensitive adhesive label film roll 17, and a concealing layer film roll 19. First, the concealing layer 5 which is an opaque resin film is supplied from the concealing layer film roll 19, and printing is performed on one side of the concealing layer 5 by the printing machine 12 to form the printing layer 2 b. Subsequently, printing is performed on the other surface of the concealing layer 5 by the printing machine 12 to form the printing layer 2a. Next, the base material 1 is supplied from the base film roll 11 and bonded onto the printing layer 2a. An adhesive is applied onto the printing layer 2b by the coating machine 13, and an ultraviolet lamp 14 is used. Curing by UV irradiation. The separator 4 is supplied from the separator roll 15 onto the pressure-sensitive adhesive layer 3 formed in this manner, and bonded together.

  From the side of the film on which the substrate 1 is bonded, a half-cut cutter 16 is punched into a predetermined label shape so as not to punch out only the separator. After punching, an unnecessary part of the film is peeled off from the separator and wound on an adhesive label sheet roll 17 to obtain an adhesive label sheet in which adhesive labels are arranged on the separator. In the manufacturing method of this adhesive label, it is not limited to the said manufacturing method, For example, you may use for the application | coating of an adhesive using the concealment layer 5 film which printed both surfaces beforehand, and adhesive layer 3 is used. A separator that has been coated in advance and UV-cured may be used. Moreover, the order of application of the base material 1 to the concealing layer 5 and application to the adhesive on the opposite surface of the concealing layer 5 may be switched. Further, an adhesive layer may be provided between the printing layer 2 a on the concealing layer 5 and the substrate 1.

The coating machine 13 used for the application of the pressure-sensitive adhesive of the present invention may be any coating machine as long as it can be applied by heating and melting the pressure-sensitive adhesive composition, such as a known hot melt coater. Is used. As the light source of the ultraviolet lamp 14 used for curing the ultraviolet curable acrylic hot melt pressure-sensitive adhesive of the present invention, a known light source may be used. Low pressure mercury lamp, high pressure mercury lamp, metal halide lamp, xenon lamp, arc lamp, gallium lamp Etc. The ultraviolet curable hot-melt pressure-sensitive adhesive composition of the present invention is usually heated and melted in the range of 20 to 160 ° C., preferably 100 to 150 ° C., and then irradiated with ultraviolet rays having a wavelength region of 200 to 450 nm. Can be cured and put to practical use. Moreover, the light irradiation amount to the pressure-sensitive adhesive of the present invention usually can be put into practical use by being irradiated with a range of 50~1000mJ / cm ^2, at least 100 mJ / cm ^2, unprecedented described below It is characterized by high performance.

(1) A light intensity of 100 mJ / cm ² irradiated from a high-pressure mercury lamp is applied to a resin film in which the ultraviolet curable hot-melt pressure-sensitive adhesive composition of the present invention is applied in a sheet shape with a thickness of 20 to 50 μm on a PET film. Irradiate a dose of ultraviolet light. Separately, in accordance with the measuring method of holding force described in JIS Z 0237, a test plate is prepared by polishing a SUS304 steel plate with No. 280 sandpaper. In addition, a test piece having a width of 25 mm and a length of 300 mm is cut out from the resin film, and the test piece after light irradiation is pasted so that an area of 25 mm × 25 mm is in contact with one end of the test plate. Bend with the layer inside. A 2 kg rubber roller was moved from the top of the test piece at a speed of 300 mm / min and reciprocated once to apply a load to the test piece for pressure bonding, and then left in a creep tester tester maintained at a temperature of 70 ° C. for 30 minutes. After that, a stainless steel plate was installed so that a force was applied in the shearing direction to the bonding surface, a load of 1 kg was applied with the other end of the test piece down, and the test piece dropped from the test plate while maintaining the temperature at 70 ° C. The holding time until it is 180 minutes or more.

(2) In accordance with the method for measuring adhesive strength described in JIS Z 0237, a test plate obtained by polishing a SUS304 steel plate with No. 280 sandpaper is prepared, and the present invention is formed so as to have a film thickness of 20 to 50 μm on the PET film. A test piece having a width of 15 mm and a length of 250 mm was cut out from the resin film after the UV curable hot-melt pressure-sensitive adhesive composition was applied and irradiated with ultraviolet light at a dose of 100 mJ / cm ² irradiated from a high-pressure mercury lamp. One end of the test piece is attached to one end of the test plate so that an area of 15 mm × 100 mm is in contact with the test piece, and a 2 kg rubber roller is moved at a speed of 300 mm / min to reciprocate once to load the test piece. After applying pressure, a 5 kg load cell was installed, and a 180 ° peel test was conducted at a speed of 300 mm / min using a tensile tester with the temperature adjusted to 23 ° C. It adhesive strength at that time is 1.96N / 15mm (200g · f) above, is.

Moreover, although the application amount of the adhesive of this invention is the range whose thickness of an adhesive layer is 100 micrometers or less normally, neither a base material nor an application amount is specifically limited. Particularly preferably, when the film thickness is 10 to 50 μm, it has been found that the ultraviolet light having a low irradiation amount of 100 mJ / cm ² has very high performance as described above.

  In the pressure-sensitive adhesive label of the present invention, the hot-melt pressure-sensitive adhesive to be used is a copolymer represented by the acrylic polymerizable monomers (a) and (b) in the pressure-sensitive adhesive and the general formula (I) or (II). By having a polymerizable benzophenone (c), it exhibits higher activity with respect to ultraviolet light than before, so that it can be cured at a low ultraviolet light amount, and has a hydrocarbon substituent having 1 to 4 carbon atoms. By containing 10 to 99% by mass of the acrylate ester polymerizable monomer (a), the thermal stability is good without deteriorating the adhesive property even if it is kept for a certain period of time in a high temperature atmosphere. Productivity of adhesive labels is good because of excellent workability. In addition, the pressure-sensitive adhesive label of the present invention has good pressure-sensitive adhesive properties such as pressure-sensitive adhesive force, holding power, and tack, and particularly has a low content of compounds that can cause odor.

  EXAMPLES Synthesis examples, examples and comparative examples according to the present invention will be described below. However, the present invention is not limited to the following examples, and can be arbitrarily changed within the scope of the present invention. “Part” and “%” are both based on mass.

Production Example 1 [Production of Vinyl Copolymer Solution (A-1)]
In a reactor equipped with a reflux apparatus, a thermometer, a stirrer, a dropping apparatus, and a nitrogen introduction tube, 65 parts by mass of ethyl acetate, 10 parts by mass of 2-propanol, 24.75 parts by mass of methyl acrylate, 70 parts by mass of n-butyl acrylate , 50 parts by mass of a mixture consisting of 5 parts by mass of acrylic acid, 0.25 parts by mass of 4-methacryloyloxybenzophenone, 0.02 parts by mass of azobisisobutyronitrile, and heated to 80 ° C. in a nitrogen atmosphere while stirring. . Next, while heating the reaction solution under a nitrogen atmosphere, the remainder of the mixture was added over 150 minutes using a dropping device, and further reacted at 80 ° C. for 1 hour. Next, 2 parts by mass of an azobisisobutyronitrile ethyl acetate solution (5% by mass) is added 4 times every 1 hour, and further heated for 2 hours. A solution (A-1) was obtained.

Production Examples 2 to 10 [Production of vinyl copolymer solutions (A-2) to (A-10)]
Except having changed the solvent composition and monomer composition in the said manufacture example 1 as described in Table 1, 2, it manufactures similarly to the said manufacture example 1, and vinyl-type copolymer solution (A-2)-( A-10) was obtained. In addition, all the compounding quantities of each composition of Table 1, 2 are a mass part.

  The physical properties of the vinyl copolymers (A-1) to (A-10) were measured and calculated according to the following methods and listed in Tables 1 and 2.

(1) Weight average molecular weight The polystyrene equivalent weight average molecular weight was measured by the gel permeation chromatography (GPC) method.

(2) Glass transition temperature Tg (° C)
It calculated | required from the calculated value using the following Fox formula.
1 / (Tg + 273) = Σ (Wi / Tgi)
(In the formula, Wi represents the weight fraction of various components, and Tgi represents the Tg (K) of the homopolymer of various synthetic components. However, Tg excludes the component (c) and (a) + (b) + (This is a value obtained by converting (d) to 100% by mass.)

In Tables 1 and 2, the abbreviations have the following meanings.
MMA: methyl methacrylate MA: methyl acrylate BA: n-butyl acrylate EHA: 2-ethylhexyl acrylate AA: acrylic acid MAA: methacrylic acid I-1: 4-methacryloyloxybenzophenone

[Examples 1 to 4, Comparative Examples 1 to 6]
The vinyl copolymer (A-1 to A-10) solution obtained in the above production example was heated under reduced pressure at 130 ° C. to remove the solvent, and an ultraviolet curable acrylic hot melt pressure-sensitive adhesive was obtained. Tables 3 and 4 show the results of quantifying the residual monomer amount of component (a) and component (d) and the amount of alcohol which is a thermally decomposable product of the ester side chain contained in the obtained adhesive by GC analysis. did. The results after holding at 140 ° C. for 6 hours are also shown in Tables 3 and 4.

表中、*は定量下限以下であることを示す。

In the table, * indicates that it is below the lower limit of quantification.

表中、*は定量下限以下であることを示す。

In the table, * indicates that it is below the lower limit of quantification.

  A transparent PET film having a thickness of 38 μm printed on the back surface using a hot melt coater in a state where the pressure-sensitive adhesives obtained in Examples 1 to 4 and Comparative Examples 1 to 6 were heated and melted. On the printed layer, an adhesive was applied to a thickness of 20 to 50 μm and cooled to room temperature. The coating properties at this time were evaluated according to the following criteria.

Irradiation with ultraviolet rays using an 80 W / cm high-pressure mercury lamp in the air so that the energy to be irradiated is 100 mJ / cm ² (actual value measured by integrating light meter UV-350 (manufactured by Oak Co., Ltd.)). Then, the pressure-sensitive adhesive layer was cured to obtain a pressure-sensitive adhesive label. Table 5 shows the evaluation results of the properties of the obtained pressure-sensitive adhesive label. Moreover, an adhesive label is similarly created using the adhesive after hold | maintaining each adhesive in the said Examples 1-4 and Comparative Examples 1-6 at 140 degreeC for 6 hours, The characteristic of an adhesive label The evaluation results are shown in Table 6.

Coating property: The state of coating on a glass plate with an applicator so as to have a dry film thickness of 20 to 50 μm was determined according to the following criteria.
○: Viscosity at 150 ° C. is lower than 40000 mPa · s and coating property is good Δ: Viscosity at 150 ° C. is 40000 to 50000 mPa · s and there is no problem in coating property.
X: Viscosity at 150 ° C. is higher than 50000 mPa · s, and there is a problem in coatability.
(○ and △ are acceptable and × are unacceptable)
The holding power, adhesive strength, and tack of the obtained adhesive label were tested and evaluated according to the following methods.

(1) Holding power A dose of light of 100 mJ / cm ² irradiated from a high-pressure mercury lamp onto a resin film in which a UV curable hot-melt adhesive composition is applied in a sheet form to a thickness of 20 to 50 μm on a PET film Irradiate UV light. Separately, in accordance with the measuring method of holding force described in JIS Z 0237, a test plate is prepared by polishing a SUS304 steel plate with No. 280 sandpaper. In addition, a test piece having a width of 25 mm and a length of 300 mm is cut out from the resin film, and the test piece after light irradiation is attached so that an area of 25 mm × 25 mm is in contact with one end of the test plate. Bend with the layer inside. A 2 kg rubber roller is moved from the top of the test piece at a speed of 300 mm / min, reciprocated once to apply pressure to the test piece, and then left to stand in a creep tester tester maintained at a temperature of 70 ° C. for 30 minutes. After that, a stainless steel plate was installed so that a force was applied in the shearing direction to the bonding surface, a 1 kg load was applied with the other end of the test piece down, and the test piece dropped from the test plate while maintaining the temperature at 70 ° C. The holding time until it was measured was measured. If the holding time was 180 minutes or more, it was considered acceptable.

(2) Adhesive strength In accordance with the method for measuring adhesive strength described in JIS Z 0237, a test plate is prepared by polishing a SUS304 steel plate with No. 280 sandpaper so that the film thickness is 20 to 50 μm on the PET film. A test piece having a width of 15 mm and a length of 250 mm was cut out from the resin film after applying the ultraviolet curable hot-melt pressure-sensitive adhesive composition and irradiating with ultraviolet light at a dose of 100 mJ / cm ² irradiated from a high-pressure mercury lamp, One end of this test piece is attached to one end of this test plate so that an area of 15 mm × 100 mm is in contact with it, and a 2 kg rubber roller is moved at a speed of 300 mm / min to reciprocate once to load the test piece. After crimping, install a 5 kg load cell and perform a 180 ° peel test at a speed of 300 mm / min using a tensile tester with the temperature adjusted to 23 ° C. It was measured the adhesive force at that time. If the adhesive strength was 1.96 N / 15 mm (200 g · f) or more, it was determined to be acceptable.

(3) Tack Measured by the rolling ball method at a temperature of 23 ° C. according to JIS Z 0237. In addition, the numerical value described in the result is the ball number used. It is.

  The pressure-sensitive adhesive label satisfying the conditions of the present invention had all excellent coating properties, transparency and pressure-sensitive adhesive properties as shown in Examples 1 to 4. On the other hand, as shown in Comparative Examples 1 to 6, the pressure-sensitive adhesive label that does not satisfy the conditions of the present invention did not satisfy all the coating properties, transparency, and pressure-sensitive adhesive properties.

(4) Odor Odorability: The odor of the pressure-sensitive adhesive label obtained on the PET film was subjected to sensory evaluation.
○: Odor is not worrisome, and there is no problem with odor.
Δ: Slightly odor but no problem due to odor.
X: Strong odor and problematic due to odor.
(○ and △ are acceptable and × are unacceptable)

  Although it is a pressure-sensitive adhesive composition obtained by polymerizing a copolymerizable benzophenone, the pressure-sensitive adhesive composition of Comparative Examples 1 and 3 having a weight average molecular weight outside the range of 50,000 to 350,000, and (b) component α, β-unsaturated In the pressure-sensitive adhesive compositions of Comparative Examples 2 and 4 in which the carboxylic acid polymerizable monomer was outside the range of 1 to 13% by mass, the balance between coatability and tack was poor. In addition, the pressure-sensitive adhesive composition of Comparative Example 6 that does not contain an acrylate polymerizable monomer having a hydrocarbon substituent having 1 to 4 carbon atoms as the component (a) remains at 140 ° C. for 6 hours. Alcohol, which is a thermally decomposable product of the monomer and polymer side chain ester, was produced in a large amount, resulting in poor odor and a marked decrease in holding power. In Comparative Example 5 in which the copolymerizable benzophenone was not polymerized, the holding power was low. Further, Comparative Example 1 in which the weight average molecular weight is larger than the specified range, Comparative Example 4 in which the component (b) is less than the specified range, and Comparative Example 6 in which the component (a) is not used, have insufficient adhesive strength. .

  On the other hand, Examples 1-4 in the range of the pressure-sensitive adhesive composition of the present invention have good coating properties, excellent balance of pressure-sensitive adhesive force, holding power, and tack, and remain even when held at 140 ° C. for 6 hours. The production amount of alcohol, which is a thermally decomposable product of the monomer and polymer side chain ester, was small and the odor was good, and the adhesive property was not deteriorated.

  The pressure-sensitive adhesive label of the present invention uses the ultraviolet curable acrylic hot-melt pressure-sensitive adhesive of the present invention for the pressure-sensitive adhesive layer and is copolymerized with a copolymerizable benzophenone (c), so that it can be cured at a low ultraviolet light amount. It is possible to improve the hot melt coating property, improve the productivity, reduce the manufacturing cost, have excellent weather resistance, excellent adhesive properties even if held for a certain period of time in a high temperature atmosphere, and can cause odor The content of is small, and the adhesiveness in a high temperature atmosphere is excellent. Furthermore, since there is no bleeding such as bleeding out of the pressure-sensitive adhesive, and no solvent is contained, there is an advantage that the printed layer is not affected and the label is easily cut when it is cut.

  Moreover, since the adhesive label of this invention has the said adhesive layer, a base material, and a printing layer and has a printing layer between a base material and an adhesive layer, a base material becomes a protective layer. Does not damage the printed layer. Moreover, since the base material is a transparent material and the said adhesive layer is also excellent in transparency, the adhesive label of this invention is a transparent adhesive label excellent in transparency. Furthermore, since printing is performed so that printing of the printing layer can be normally viewed from the transparent substrate side, the pattern can be seen through the transparent substrate, and the surface of the pattern of the printing layer is transparent. Since it is covered with the base material, there is no risk of the pattern being deteriorated by scratches, water drops, or the like without forming a protective layer on the printed layer.

  In addition, since the pressure-sensitive adhesive label of the present invention is printed so that the printing of the printed layer can be normally seen from the pressure-sensitive adhesive layer side, the liquid filled in the glass bottle and the glass bottle, for example, when attached to a glass bottle or the like Through this, you can see the printed picture normally. Moreover, the pressure-sensitive adhesive label of the present invention has the pressure-sensitive adhesive layer, the transparent base material, the printing layer, and the masking layer, and between the transparent substrate and the masking layer and between the masking layer and the pressure-sensitive adhesive layer. Since the ultraviolet curable acrylic hot melt pressure-sensitive adhesive used in the pressure-sensitive adhesive layer has excellent transparency, the printed pattern printed on one side of the concealing layer can be seen through the transparent substrate. In addition, another printed pattern printed on the other side of the hiding layer can be seen from the pressure-sensitive adhesive layer side.

  In the method for producing the pressure-sensitive adhesive label of the present invention, after printing on one side of the substrate to form a printed layer, the ultraviolet curable acrylic hot melt pressure-sensitive adhesive is hot-melt coated on the printed layer, It is characterized by curing the pressure sensitive adhesive by irradiating the pressure sensitive adhesive layer with an ultraviolet ray, so that the pressure sensitive adhesive layer has excellent transparency, adhesiveness, heat stability, weather resistance, and heat resistance. Can be manufactured automatically.

  In the method for producing the pressure-sensitive adhesive label of the present invention, after printing is performed on one side of a base material to form a printing layer, a concealing layer that is an opaque layer is formed thereon, and printing is further performed on the concealing layer. After the layer is formed, the ultraviolet curable acrylic hot melt pressure-sensitive adhesive is hot-melt coated on the printed layer, and then the pressure-sensitive adhesive layer is irradiated with ultraviolet rays to cure the pressure-sensitive adhesive. Therefore, the transparency of the pressure-sensitive adhesive layer is excellent, and the pressure-sensitive adhesive label has excellent adhesiveness, heat stability, weather resistance, and heat resistance, and another printed pattern can be seen from both sides of the pressure-sensitive adhesive label. Such an adhesive label can be manufactured efficiently.

  In the method for producing the pressure-sensitive adhesive label of the present invention, after printing is performed on both sides of the concealing layer to form a printing layer, a substrate is bonded onto one printing layer, and the above-mentioned printing layer is placed on the other printing layer The adhesive layer is excellent in transparency because it is characterized in that UV-curable acrylic hot melt adhesive is hot-melt coated and then the adhesive layer is irradiated with ultraviolet rays to cure the adhesive. The pressure-sensitive adhesive label has excellent adhesiveness, heat stability, weather resistance, and heat resistance. Further, different printed patterns can be seen from both sides of the pressure-sensitive adhesive label, and such a pressure-sensitive adhesive label can be produced efficiently. .

  From the above, it is very useful industrially.

It is sectional drawing which shows an example of the adhesive label of this invention. It is sectional drawing which shows another example of the adhesive label of this invention. It is a schematic diagram which shows an example of the manufacturing apparatus which performs the manufacturing method of the adhesive label of this invention. It is a schematic diagram which shows an example of the manufacturing apparatus which performs the manufacturing method of the adhesive label of this invention. It is a schematic diagram which shows an example of the manufacturing apparatus which performs the manufacturing method of the adhesive label of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base material 2 Print layer 3 Adhesive layer 5 Concealment layer

Claims (10)

An ultraviolet curable hot melt pressure-sensitive adhesive composition containing a vinyl copolymer (A) having a glass transition temperature of −5 ° C. or lower and a weight average molecular weight of 50,000 to 350,000, wherein the vinyl copolymer (A ) Is obtained by polymerizing the following monomer components (a) to (d) as constituent components: an ultraviolet curable hot-melt pressure-sensitive adhesive composition.
(A) 10 to 99% by mass of an acrylate polymerizable monomer having a hydrocarbon substituent having 1 to 4 carbon atoms,
(B) 1 to 13% by mass of an α, β-unsaturated carboxylic acid polymerizable monomer,
(C) 0.01 to 10% by mass of at least one selected from copolymerizable benzophenones represented by the following general formula (I) or (II):
(D) 0 to 88.9 mass% of other copolymerizable vinyl monomers
(However, the total of (a) + (b) + (c) + (d) is 100% by mass)

(In the formula, R and R ′ each independently represent an alkyl group, a carboxyl group, or a halogen atom, n represents an integer of 0 to 5, m represents an integer of 0 to 4, and X represents (meta) Represents an acryloyloxy group or a (meth) acryloyloxyalkyleneoxy group.)   The amount of decomposition product of the polymer side chain ester of the component (a) and the component (b), or the component (d), which is increased by holding the vinyl copolymer (A) from which the volatile component has been separated at 140 ° C. for 6 hours. 2. The ultraviolet curable hot melt according to claim 1, wherein the amount of decomposition products of the polymer side chain esters of the components (a), (b) and (d) is 3000 ppm or less in total. Adhesive composition.   A pressure-sensitive adhesive sheet comprising the ultraviolet curable hot-melt pressure-sensitive adhesive composition according to claim 1 or 2 as a pressure-sensitive adhesive layer.   The pressure-sensitive adhesive sheet-like material is a pressure-sensitive adhesive label having the pressure-sensitive adhesive layer, a base material, and a printing layer, and has the printing layer between the base material and the pressure-sensitive adhesive layer. Item 4. The pressure-sensitive adhesive sheet-like material according to Item 3.   The pressure-sensitive adhesive sheet-like sheet according to claim 4, wherein the base material is made of a transparent material, and is printed so that the printing of the printed layer can be normally seen when viewed from the base material side. object.   The pressure-sensitive adhesive sheet-like article according to claim 4, wherein the printed layer is printed so that printing can be normally seen when viewed from the pressure-sensitive adhesive layer.   The pressure-sensitive adhesive sheet-like material is a pressure-sensitive adhesive label having the pressure-sensitive adhesive layer, a transparent base material, a printing layer, and a concealing layer, and between the transparent base material and the concealing layer and between the concealing layer and the pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheet-like product according to claim 3, further comprising a printed layer therebetween.   After printing on one side of the base material to form a printing layer, UV-curable acrylic hot melt adhesive is hot-melt coated on the printing layer, and then the adhesive layer is irradiated with ultraviolet rays to form an adhesive. The method for producing a pressure-sensitive adhesive label using the ultraviolet curable hot-melt pressure-sensitive adhesive composition according to claim 5, wherein:   After printing on one side of the base material to form a printing layer, an opaque layer that is an opaque layer was formed thereon, and printing was performed on the other side of the shielding layer to form a printed layer. 8. The pressure-sensitive adhesive according to claim 7, wherein a UV-curable acrylic hot-melt pressure-sensitive adhesive is subsequently hot-melt coated on the printed layer, and then the pressure-sensitive adhesive layer is irradiated with ultraviolet rays to cure the pressure-sensitive adhesive. Label manufacturing method.   After printing on both sides of the concealing layer to form a printing layer, a substrate is bonded onto one printing layer, and an ultraviolet curable acrylic hot melt adhesive is hot-melted onto the other printing layer. The method for producing a pressure-sensitive adhesive label according to claim 7, wherein the pressure-sensitive adhesive is cured by applying ultraviolet rays to the pressure-sensitive adhesive layer.

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