JP2007009103A - Adhesive and adhesive processed article obtained by using the same adhesive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive processed article such as an adhesive sheet, capable of exhibiting sufficient performance in shorter curing time and scarcely generating formaldehyde from an adhesive not containing toluene and halogens. <P>SOLUTION: The adhesive comprises a copolymer obtained by copolymerizing radically polymerizable monomers essentially containing a carboxyl group-containing radically polymerizable monomer by using at least one kind of compound selected from a group consisting of α-pinene, limonene and terbinolene in the absence of toluene and in the presence of at least one kind of organic solvent selected from a group consisting of ethyl acetate, acetone, methylethyl ketone and methylisobutyl ketone, and an organometallic compound, and does not contain a halogen compound. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an adhesive and an adhesive processed product using the adhesive, that is, a coated product. Specifically, the demands of the social environment that do not contain toluene and halogen compounds, and the time (so-called curing time) until adhesive processed products made by applying adhesives to various substrates exhibit sufficient performance are shortened. The present invention relates to a pressure-sensitive adhesive that meets the technical demands to be applied.

Conventionally, in the field of organic solvent-type pressure-sensitive adhesives, compounds having isocyanate groups have been used as curing agents for copolymers obtained by polymerizing radically polymerizable monomers.
In this case, the main polymer is often polymerized in the presence of toluene. In addition to functioning as a solvent for the monomer and the polymer produced, toluene also functions as a chain transfer agent during polymerization. In addition, post-polymerization toluene is often used as a diluent for viscosity adjustment. However, in recent years, pressure-sensitive adhesives that do not contain toluene have been demanded from the environmental viewpoint.
Similarly, it has been demanded not to contain a halogen compound from the viewpoint of the environment.
Furthermore, a reduction in formaldehyde that can be generated from the processed adhesive product has been demanded.

  In response to such a requirement, in the absence of toluene, in the presence of at least one organic solvent selected from the group consisting of ethyl acetate, acetone, methyl ethyl ketone and methyl isobutyl ketone, α-pinene, limonene and terpinolene are used. A copolymer obtained by copolymerizing a radically polymerizable monomer essentially comprising a carboxyl group-containing radically polymerizable monomer, and an isocyanate compound, using at least one compound selected from the group consisting of: An invention relating to a pressure-sensitive adhesive not contained was proposed in Patent Document 1 (Japanese Patent Laid-Open No. 2005-139323).

In general, pressure-sensitive adhesives are applied to various substrates, and after completion of heating and drying, a certain amount of time until the physical properties of the adhesive processed product, for example, adhesive performance such as adhesive strength and holding power, is stabilized (so-called “curing time”) Is required). When an isocyanate compound is used as a curing agent, a curing time of about 1 week is required for standing storage at room temperature and normal humidity, for example, in an atmosphere of 23 ° C.-50% RH.
In addition, polar solvents such as ethyl acetate and isopropyl alcohol have a high affinity for water as compared to nonpolar solvents such as toluene. Therefore, when such a polar solvent is contained, if an isocyanate compound is used as a curing agent, the storage stability of the pressure-sensitive adhesive may be lowered.
JP 2005-139323 A

  An object of the present invention is to provide a pressure-sensitive adhesive product such as a pressure-sensitive adhesive sheet that can exhibit sufficient performance with a shorter curing time and that generates less formaldehyde from a pressure-sensitive adhesive that does not contain toluene and halogens.

  The present invention is the group consisting of α-pinene, limonene and terpinolene in the absence of toluene and in the presence of at least one organic solvent selected from the group consisting of ethyl acetate, acetone, methyl ethyl ketone and methyl isobutyl ketone. Contains a copolymer obtained by copolymerizing a radically polymerizable monomer essentially containing a carboxyl group-containing radically polymerizable monomer using at least one compound selected from the above, an organometallic compound, and a halogen compound It is related with the adhesive characterized by not doing.

  Further, the present invention is characterized in that 0.001 to 5.0 parts by weight of at least one compound selected from the group consisting of α pinene, limonene and terpinolene is used with respect to 100 parts by weight of the radical polymerizable monomer. The present invention relates to the pressure-sensitive adhesive described in the above invention.

  Moreover, this invention relates to the adhesive in any one of the said invention characterized by containing 0.001-30 weight part of organometallic compounds with respect to 100 weight part of copolymers.

  Furthermore, this invention relates to the adhesive in any one of the said invention characterized by containing acetylacetone.

  Furthermore, this invention relates to the adhesive processed product which provides the adhesive layer formed from the adhesive in any one of the said invention on a base material.

  According to the present invention using an organometallic compound as a curing agent, it becomes possible to exhibit sufficient adhesive performance in a shorter curing time as compared with the case of a conventional adhesive using an isocyanate compound as a curing agent, and production. Improved.

The pressure-sensitive adhesive of the present invention is one in which ethyl acetate, acetone, methyl ethyl ketone, and methyl isobutyl ketone are used alone or in combination of two or more as a substitute solvent for toluene when the copolymer as the main component is polymerized. In view of temperature, ethyl acetate alone is slightly preferred.
Instead of toluene, the copolymerization of radically polymerizable monomers essentially containing carboxyl group-containing radically polymerizable monomers in the presence of these organic solvents is the same as the copolymer obtained in the presence of toluene. The weight average molecular weight of the coalescence increases, and as a result, the viscosity of the pressure-sensitive adhesive increases, causing a decrease in coating properties and a decrease in pressure-sensitive adhesive performance.
The present invention not only uses an organic solvent other than toluene, but also when polymerized in the presence of conventional toluene by using at least one of α-pinene, limonene, and terpinolene as a chain transfer agent during polymerization. It is now possible to obtain a copolymer having a weight average molecular weight or the like that is not significantly different from that of the copolymer.
α-pinene and the like can adjust the molecular weight of the copolymer obtained depending on the amount used. α-pinene and limonene are preferably used in an amount of 0.1 to 5.0 parts by weight, more preferably 0.3 to 3.0 parts by weight, and more preferably 0.5 to 1 part per 100 parts by weight of the radical polymerizable monomer. More preferably, 3 parts by weight are used. The terpinolene is preferably used in an amount of 0.001 to 1.0 part by weight, more preferably 0.01 to 0.05 part by weight, based on 100 parts by weight of the radical polymerizable monomer.

Turpinolene is preferable in that the molecular weight can be adjusted in a small amount as compared with α-pinene and limonene, but it affects the molecular weight of the resulting copolymer depending on the amount used. Accordingly, α-pinene and limonene are slightly preferred from the viewpoint of producing a copolymer having a constant property with good reproducibility in consideration of weighing errors and the like.
Limonene has a citrus scent, although it is not an intense and unique unpleasant odor like a compound having a thiol group. Therefore, α-pinene is slightly preferable to limonene when an adhesive with low fragrance is required.

The copolymer which is a main component constituting the pressure-sensitive adhesive of the present invention may be any having a carboxyl group. The copolymer having a carboxyl group may be copolymerized with a monomer having a carboxyl group-containing radical polymerizable monomer as an essential component.
Examples of the carboxyl group-containing radical polymerizable monomer include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, and crotonic acid.

Examples of the monomer containing another functional group that can be copolymerized with the carboxyl group-containing radical polymerizable monomer include a hydroxyl group-containing radical polymerizable monomer. Examples of the hydroxyl group-containing radical polymerizable monomer preferably used in the present invention include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, glycerol mono (meth) acrylate, and the like. Is mentioned.
In the present invention, 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are slightly preferred.

  Other (meth) acrylic monomers used in the present invention include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, 2-ethylhexyl ( (Meth) acrylate, heptyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) Acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (medium ) Acrylate, eicosyl (meth) acrylate, heneicosyl (meth) acrylate and docosyl (meth) acrylate. In the present invention, it is preferable to use an acrylic monomer having 4 to 12 carbon atoms for copolymerization in that preferable adhesive properties are easily obtained. More preferred are methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate.

  Examples of other radical polymerizable monomers having no carboxyl group or hydroxyl group include vinyl acetate monomer, styrene monomer, vinyl propionate monomer and the like.

In the polymerization, conventionally known polymerization initiators such as peroxide-based polymerization initiators and azobis-based polymerization initiators can be used.
These polymerization initiators are preferably used in an amount of 0.02 to 2.0 parts by weight, more preferably 0.10 to 1.0 parts by weight, based on 100 parts by weight of the monomer.

  The resulting copolymer preferably has a weight average molecular weight (hereinafter referred to as MW) in terms of polystyrene of gel permeation chromatography of 400,000 to 1,200,000, and more preferably 600,000 to 800,000. When the MW is less than 400,000, the heat resistance performance and cohesive force of the coated product are poor, and when the MW is 1,200,000 or more, the adhesive strength and the coating performance tend to decrease, which is not preferable.

  In addition, considering that the obtained copolymer is the main component of the pressure-sensitive adhesive, the glass transition temperature required from the monomer subjected to copolymerization is preferably 0 ° C. to −80 ° C., and −20 ° C. It is more preferable that the temperature is -60C.

  Examples of the organometallic compound used as a curing agent in the present invention include an organotitanium compound, an organozirconium compound, and an organoaluminum compound, and 0.001 to 30 parts by weight with respect to 100 parts by weight of the copolymer. Is preferred. It is more preferable to use 0.01 to 15.0 parts by weight. When it is less than 0.001 part by weight, the crosslinking density when cured with the main agent is small, the cohesive force of the obtained pressure-sensitive adhesive layer becomes weak, and the performance such as heat resistance becomes poor. When the amount is more than 30 parts by weight, the crosslinking density when cured with the copolymer is large, and the adhesive strength of the resulting adhesive layer becomes poor, which is not preferable.

In the case of a pressure-sensitive adhesive containing an isocyanate compound, in order to suppress the reaction between the isocyanate compound and water, it has been common so far to incorporate a halogen compound such as benzoyl chloride into the pressure-sensitive adhesive as a moisture scavenger. .
However, when an organometallic compound is used as the curing agent, a halogen compound such as benzoyl chloride may not be contained in the adhesive.

By using the pressure-sensitive adhesive of the present invention, pressure-sensitive adhesive products used in various applications and fields can be obtained. For example, it can be suitably used as an adhesive for adhering an interior / exterior member of a building or a member of a home appliance. When used for an object placed in a room after being attached, such as an interior member of a building or a member of a home appliance, it is preferable to contain acetylacetone in the pressure-sensitive adhesive of the present invention.
By containing acetylacetone in the adhesive, the amount of formaldehyde generated from the processed adhesive product can be suppressed. It is preferable to add 0.01-2.0 weight part of acetylacetone with respect to 100 weight part of adhesives, and it is more preferable to add 0.05-1 weight part. If the amount is less than 0.01 parts by weight, the effect of collecting formaldehyde is thin. If the amount exceeds 2.0 parts by weight, the effect of collecting formaldehyde is increased, but the adhesive is applied to a substrate described later, dried, and subjected to an adhesive process. When a product is obtained, it may remain in the pressure-sensitive adhesive layer, resulting in insufficient cohesive force.

  Furthermore, in the pressure-sensitive adhesive of the present invention, fillers, pigments, dyes, diluents, anti-aging agents, polymerization inhibitors, UV absorbers, UV stabilizers blended in known pressure-sensitive adhesive compositions as necessary. Various additives such as these may be contained. Only one kind of these additives may be used, or two or more kinds may be appropriately used. Moreover, the addition amount of an additive should just be taken as the quantity from which the desired physical property is obtained, and is not specifically limited.

The pressure-sensitive adhesive having the above-described configuration can be applied to any application using a known pressure-sensitive adhesive composition.
That is, the pressure-sensitive adhesive according to the present invention can be suitably used for manufacturing various pressure-sensitive adhesive processes such as pressure-sensitive adhesive sheets, pressure-sensitive adhesive tapes, pressure-sensitive adhesive labels, and double-sided tapes. Specific examples of the base material of the above-mentioned adhesive processed product include polyethylene, polypropylene, polyester, polystyrene, polyethylene terephthalate (hereinafter referred to as PET), polyvinyl chloride, polycarbonate, cellophane, and the like; fine paper, kraft paper, and crepe paper Paper such as glassine paper; cloth such as woven fabric and non-woven fabric; and the like, but is not particularly limited. Examples of the shape of the substrate include a film shape, a sheet shape, a tape shape, and a plate shape, but are not particularly limited. Moreover, when a base material is a plastic, a foam may be sufficient.

  The application method for applying the pressure-sensitive adhesive to the substrate, that is, the method for producing the pressure-sensitive processed product is not particularly limited, and various known methods can be employed. Examples of the method include a method in which a pressure-sensitive adhesive is directly applied to a substrate; a method in which the pressure-sensitive adhesive is applied to a release paper, and then the coated material is transferred to the substrate. The pressure-sensitive adhesive can be easily applied to the substrate. The application apparatus used when apply | coating an adhesive to a base material is not specifically limited. And after apply | coating an adhesive to the single side | surface or both surfaces of a base material, it is made to dry, and a base material and an adhesive are integrated, and an adhesive layer (henceforth an adhesive surface) is formed in the base material surface. The The drying temperature is not particularly limited. Depending on the application, the pressure-sensitive adhesive composition may be applied directly to the adherend. In addition, after the adhesive is applied to the release paper, the coated product is peeled from the release paper, thereby producing an adhesive product in which the adhesive itself is formed into a film, sheet, tape, plate, or the like. You can also.

The present invention will be described based on examples. In the examples, “part” is “part by weight”, and “%” is “% by weight”.

[Example 1]
Using a polymerization apparatus equipped with a stirrer, thermometer, dropping funnel, and refluxing apparatus, 64.9 parts of butyl acrylate, 25 parts of 2-ethylhexyl acrylate, 7 parts of ethyl acrylate, 3 parts of acrylic acid, hydroxyethyl acrylate 0 0.1 part, ethyl acetate 120 parts, α-pinene 0.85 part, and benzoyl peroxide 0.03 part were copolymerized under reflux for 2 hours, and the reaction temperature was maintained for 1 hour and 2 hours later. 0.023 parts of benzoyl peroxide was added in portions. After the addition, the reaction was allowed to proceed for 2 hours, and then 0.022 parts of t-butyl-oxy-2-ethylhexanoate was added after 1 hour, 2 hours, and 3 hours. After the last addition, the reaction is further allowed to proceed for 2 hours. After cooling, when diluted with ethyl acetate and the liquid temperature reaches 60 ° C. or less, 0.1 part of hydroquinone derivative (trade name: Non-Flex Albert, Seiko Chemical Co., Ltd.) is added. After addition and sufficient stirring, the copolymer solution was taken out. The non-volatile content of the copolymer solution was 45%, and the viscosity was 25000 mPa · s. The MW of the copolymer in terms of polystyrene as determined by gel permeation chromatography (hereinafter referred to as GPC) was about 650,000.
To 177.8 parts of the obtained copolymer solution (about 80 parts by weight as a copolymer), 20 parts of tackifier resin, 0.5 parts by weight of acetylacetone, and an organometallic compound, an organoaluminum compound (trade name) : Aluminum Chelate A (manufactured by Kawaken Fine Chemical Co., Ltd.) in an amount of 6.0 parts by weight and 24.4 parts of ethyl acetate were added to obtain an adhesive having a nonvolatile content of about 45%.
In addition, the measurement of the non volatile matter was calculated | required from the weight ratio before and behind drying after 150 degreeC-20 minutes with an electric oven. The viscosity is a value measured with a B-type viscometer (# 3 rotor, 12 rpm) at 25 ° C.

  The obtained pressure-sensitive adhesive was coated on a release paper so that the dry film thickness was 25 μm, dried and cured at 100 ° C. for 2 minutes, and immediately after that, a PET film (thickness 50 μm) as a sheet base material on the pressure-sensitive adhesive layer Was pressed and stored (cured) for 72 hours or 168 hours under an atmosphere of 23 ° C.-50% RH to obtain two types of pressure-sensitive adhesive sheets for testing.

Using the two types of test pressure-sensitive adhesive sheets, tests for adhesive strength, holding power, and ball tack were performed by the following methods.
<Adhesion test method>
Release the release paper from a 10cm x 25mm test adhesive sheet, stick an adhesive layer to a polished stainless steel plate or polyethylene plate, press it once with a 2kg roll, and measure it by a 180 ° peel test 24 hours later. did.
<Retention force test method>
The release paper is peeled off from the 10 cm × 25 mm test adhesive sheet, and the adhesive layer is pasted on a polished stainless steel plate with an area of 25 mm × 25 mm. After pressing once with a 2 kg roll, a load of 1 kg is applied in an atmosphere of 40 ° C. It took 70,000 seconds to elapse, and when it was dropped, the time was measured, and when it was not dropped, the displacement distance (mm) of the sticking position was measured.
<Ball tack test method>
The test was conducted according to JIS Z 0237 tilting ball tack.

[Comparative Example 1]
Instead of the organoaluminum compound used in Example 1, an ethyl acetate solution of an aromatic diisocyanate trimethylolpropane adduct (trade name: Takenate TY-10, non-volatile content 37.5%, manufactured by Mitsui Takeda Chemical Co., Ltd.) Except for blending 2.5 parts by weight, a pressure-sensitive adhesive was obtained in the same manner as in Example 1, a test pressure-sensitive adhesive sheet was obtained in the same manner, and evaluated in the same manner.

Claims (5)

In the absence of toluene, at least one selected from the group consisting of α-pinene, limonene and terpinolene in the presence of at least one organic solvent selected from the group consisting of ethyl acetate, acetone, methyl ethyl ketone and methyl isobutyl ketone. It contains a copolymer obtained by copolymerizing a radically polymerizable monomer having a carboxyl group-containing radically polymerizable monomer as an essential component, and an organometallic compound, and does not contain a halogen compound. Adhesive. The pressure-sensitive adhesive according to claim 1, wherein 0.001 to 5.0 parts by weight of at least one compound selected from the group consisting of α-pinene, limonene and terpinolene is used with respect to 100 parts by weight of the radical polymerizable monomer. Agent. The pressure-sensitive adhesive according to claim 1 or 2, comprising 0.001 to 30 parts by weight of an organometallic compound with respect to 100 parts by weight of the copolymer. The pressure-sensitive adhesive according to any one of claims 1 to 3, comprising acetylacetone. A pressure-sensitive adhesive processed product comprising a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive according to claim 1 on a base material.