JPH11158453A - Pressure-sensitive acrylic adhesive composition and pressure-sensitive processed article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure-sensitive acrylic adhesive composition which undergoes little adhesion enhancement phenomenon and can therefore be re- released without leaving any adhesive and a pressure-sensitive processed article prepared by using the same. SOLUTION: There is provided a pressure-sensitive adhesive composition containing 100 pts.wt. acrylic copolymer obtained by radical-polymerizing a monomer component containing 74.999-99.9 wt.% following component (a), 0.1-5 wt.% following component (C), and 0-20 wt.% following component (d) and 0.1-5 pts.wt. isocyanate crosslinking agent. Component (a): a (meth)acrylic acid alkyl ester monomer, component (b): a carboxyl-containing monomer copolymerizable with component (a); component (c): a hydroxyl-containing monomer copolymerizable with component (a), and component (d): another monomer copolymerizable with component (a).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acrylic pressure-sensitive adhesive composition having excellent removability and a pressure-sensitive adhesive product produced using the same.

[0002]

2. Description of the Related Art Conventionally, pressure-sensitive adhesive products such as pressure-sensitive adhesive tapes, pressure-sensitive adhesive sheets and pressure-sensitive adhesive labels have been widely used for various uses such as stationery, packaging, building materials, home electric appliances, etc. by utilizing the simplicity of the work. In recent years, with the diversification of needs for pressure-sensitive adhesive products, there has been an increasing demand for pressure-sensitive adhesive products (so-called removable pressure-sensitive adhesive products) that can be re-peeled cleanly after pasting.

However, in a conventional ordinary pressure-sensitive adhesive composition, a phenomenon in which the adhesive strength is improved with the passage of time (elapse of time) after application (so-called adhesion enhancement phenomenon) occurs.
For example, when used under severe conditions such as floor curing in a building site, there is a problem that it cannot be peeled off cleanly.

To cope with the above problem, for example, Japanese Patent Application Laid-Open No. H08-104857 discloses that "copolymerizable vinyl monomer containing n-octyl acrylate of 10 to 99.9% by weight and active hydrogen of 0.1 to 99.9% by weight. An acrylic pressure-sensitive adhesive composition comprising a copolymer containing 10% by weight and a copolymerizable vinyl monomer containing no active hydrogen in a ratio of 0 to 89.9% by weight, and the pressure-sensitive adhesive composition on a substrate A re-peelable pressure-sensitive adhesive product which is applied and dried on a product "has been proposed.

[0005] However, since the removable pressure-sensitive adhesive product according to the above proposal has a strong adhesive force, when it is used for a material (substrate) having a low surface strength such as paper, the surface of the adherend is peeled off. There is a problem that it cannot be re-peeled cleanly.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned conventional problems, the present invention aims to solve the above-mentioned problems even when used under severe conditions such as a building site where a high temperature and a high pressure are applied. High-performance acrylic pressure-sensitive adhesive composition that hardly causes an adhesion enhancement phenomenon even when used for a weak adherend, and that can be re-peeled cleanly, and a pressure-sensitive adhesive made using the pressure-sensitive adhesive composition It is an object to provide processed products.

[0007]

Means for Solving the Problems The invention according to claim 1
Acrylic pressure-sensitive adhesive (hereinafter referred to as "first invention")
The composition contains the following component (a): 74.999 to 99.9% by weight
%, The following (b) component 0 to 0.001% by weight, the following (c1
 ) Component 0.1 to 5% by weight and the following (d1) component 0 to 2
Radical copolymerization of a monomer component containing 0% by weight
With respect to 100 parts by weight of the obtained acrylic copolymer,
0.1 to 5 parts by weight of a cyanate crosslinking agent
An acrylic pressure-sensitive adhesive composition, wherein the pressure-sensitive adhesive composition is dried.
At 120 ° C in the dynamic viscoelastic spectrum measurement of dry film
Has a storage elastic modulus of 2 × 10^Five~ 7 × 10 ^Fivedyn / cm^Two
And the loss tangent (tan δ) is 0.05 to 0.4,
And the storage elastic modulus at 0 ° C. is 1 × 10^Five~ 4 × 10⁶d
yn / cm^TwoIt is characterized by being. Component (a): (meth) acrylic acid alkyl ester mono
Component (b): carboxy copolymerizable with component (a).
(C1) component: containing a hydroxyl group copolymerizable with the component (a).
Monomer (d1) component: From the above component (b) and the above component (c1)
Other monomer copolymerizable with the above component (a)

The invention according to claim 2 (hereinafter referred to as “second
The present invention provides an acrylic pressure-sensitive adhesive composition according to (1) comprising 74.999 to 99.9% by weight of the following component (a);
Component 0-0.001% by weight, component (c2) 0.1-
An organotin compound is used in an amount of 0.1 to 100 parts by weight of an acrylic copolymer obtained by radical copolymerization of a monomer component containing 5% by weight and 0 to 20% by weight of the following component (d2).
An acrylic pressure-sensitive adhesive composition containing 5 parts by weight, wherein a storage elastic modulus at 120 ° C. in dynamic viscoelastic spectrum measurement of a dried film of the pressure-sensitive adhesive composition is 2 × 10 ⁵ to
7 × 10 ⁵ dyn / cm ^2, loss tangent (tan δ) is 0.05 to 0.4, and storage elastic modulus at 0 ° C. is 1 × 10 ⁵ to 4 × 10 ⁶ dyn / cm ² . It is characterized by the following. Component (a): alkyl (meth) acrylate monomer (b) Component: carboxyl group-containing monomer copolymerizable with component (a) Component (c2): alkoxysilyl group copolymerizable with component (a) Contained monomer (d2) component: a monomer copolymerizable with component (a) other than component (b) and component (c2)

Further, the invention according to claim 3 (hereinafter referred to as "the invention")
The pressure-sensitive adhesive product according to the “third invention” is the first product described above.
The acrylic pressure-sensitive adhesive composition according to the invention or the second invention is coated on at least one surface of a substrate.

[0010] Among the monomer components used to obtain the acrylic copolymer which is the main component of the acrylic pressure-sensitive adhesive composition according to the first or second invention, (meth) acrylic acid is used as component (a). Alkyl ester monomer 7
4.999-99.9% by weight is contained. Here, “(meth) acryl” means “acryl” or “methacryl”.

The above-mentioned component (a) may be a (meth) acrylic acid alkyl ester monomer generally used in ordinary acrylic pressure-sensitive adhesive compositions, and is not particularly limited. Ethyl acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (meth) acrylate
And octyl acrylate.
The species or two or more species are preferably used, and among them, n-butyl (meth) acrylate is more preferably used.

When the content of the component (a) in the monomer component is less than 74.999% by weight, the resulting pressure-sensitive adhesive composition has insufficient tackiness and tackiness, and conversely, When the content of the component (3) exceeds 99.9% by weight, the cohesive strength of the obtained pressure-sensitive adhesive composition decreases, and the removability and heat resistance become insufficient.

[0013] Among the monomer components used to obtain the acrylic copolymer which is the main component of the acrylic pressure-sensitive adhesive composition according to the first invention or the second invention, the above component (a) is included as the component (b). And 0 to 0.001% by weight of a carboxyl group-containing monomer copolymerizable with the above.

The component (b) is not particularly limited, but includes, for example, (meth) acrylic acid, maleic acid, itaconic acid, crotonic acid and the like, and one or more of these may be used. It is preferably used.

If the content of the component (b) in the monomer component exceeds 0.001% by weight, the resulting pressure-sensitive adhesive composition will have an excessively high tackiness or a marked increase in adhesion with time. And the removability is insufficient.

In the monomer component used to obtain the acrylic copolymer which is the main component of the acrylic pressure-sensitive adhesive composition according to the first invention, the component (c1) is copolymerizable with the component (a). Hydroxyl-containing monomer 0.1 to
It contains 5% by weight.

The component (c1) is not particularly restricted but includes, for example, 2-hydroxyethyl (meth) acrylate and 2-hydroxybutyl (meth) acrylate. One or more kinds are suitably used.

If the content of the component (c1) in the monomer component is less than 0.1% by weight, crosslinking of the resulting pressure-sensitive adhesive composition with an isocyanate-based crosslinking agent described below becomes insufficient, and the composition is re-peeled. When the content of the component (c1) exceeds 5% by weight, the crosslinking of the resulting pressure-sensitive adhesive composition with the isocyanate-based cross-linking agent proceeds excessively, resulting in insufficient tackiness and tackiness.

In the monomer component used to obtain the acrylic copolymer which is the main component of the acrylic pressure-sensitive adhesive composition according to the second invention, the component (c2) is used together with the component (a). It contains 0.1 to 5% by weight of a polymerizable alkoxysilyl group-containing monomer.

The component (c2) is not particularly limited as long as it is a monomer capable of imparting a crosslinkability due to moisture to the acrylic copolymer, and is not particularly limited. Examples thereof include methoxysilylpropyl and 3-methyldimethoxysilylpropyl (meth) acrylate, and one or more of these are suitably used.

If the content of the component (c2) in the monomer component is less than 0.1% by weight, the resulting pressure-sensitive adhesive composition will not be sufficiently crosslinked by moisture, and will have poor removability. Conversely, when the content of the component (c2) exceeds 5% by weight, the cost increases.

Among the monomer components used to obtain the acrylic copolymer which is the main component of the acrylic pressure-sensitive adhesive composition according to the first invention, the above components (b) and (c1) are included as component (d1). In addition to the component, 0 to 20% by weight of a monomer copolymerizable with the component (a) is contained.

The component (d1) is not particularly restricted but includes, for example, vinyl acetate, styrene, acrylonitrile, 3-trimethoxysilylpropyl (meth) acrylate and 3-methyldimethoxy (meth) acrylate. Silylpropyl and the like can be mentioned, and one or more of these are suitably used.

If the content of the component (d1) in the monomer component exceeds 20% by weight, the resulting pressure-sensitive adhesive composition becomes too hard, and the tack and the adhesive strength are reduced.

In the monomer component used for obtaining the acrylic copolymer which is the main component of the acrylic pressure-sensitive adhesive composition according to the second invention, the components (b) and (b) are used as the component (d2). It contains 0 to 20% by weight of a monomer copolymerizable with the component (a) other than the component c2).

The component (d2) is not particularly restricted but includes, for example, vinyl acetate, styrene, acrylonitrile, 2-hydroxyethyl (meth) acrylate and 2-hydroxybutyl (meth) acrylate. And one or more of these are preferably used.

When the content of the component (d2) in the monomer component exceeds 20% by weight, the resulting pressure-sensitive adhesive composition becomes too hard, and the tack and the adhesive strength are reduced.

The method for obtaining an acrylic copolymer by radical copolymerization of the above-mentioned monomer components is not particularly limited. Examples thereof include a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, and a bulk polymerization method. Legal, photopolymerization and the like,
Either method is suitably employed, but among them, a solution polymerization method using one or more of ethyl acetate, methyl ethyl ketone, toluene, n-hexane and the like as a solvent is simple and more preferably employed. .

When radical copolymerization is carried out by the above solution polymerization method, emulsion polymerization method, suspension assembly method, bulk polymerization method, etc., a radical polymerization initiator is used. The radical polymerization initiator is not particularly limited, for example, a peroxide-based polymerization initiator such as benzoyl peroxide, an azo-based polymerization initiator such as azobisisobutyronitrile, and the like. One or more of these are preferably used. When radical copolymerization is performed by a photopolymerization method, a photopolymerization initiator is used.

Further, in the case of performing the above-mentioned radical copolymerization, a chain transfer agent such as dodecyl mercaptan may be used in order to adjust the molecular weight of the obtained acrylic copolymer.

The molecular weight of the acrylic copolymer is not particularly limited, but may be 300,000 to 20,000 in weight average molecular weight.
Preferably, it is 10,000.

The weight average molecular weight of the acrylic copolymer is 3
When it is less than 10,000, the cohesive strength of the obtained pressure-sensitive adhesive composition becomes insufficient, and the removability and heat resistance may be reduced. On the contrary, the weight average molecular weight of the acrylic copolymer is 200.
If it exceeds 10,000, the cohesive strength of the obtained pressure-sensitive adhesive composition may be too high, and tackiness and pressure-sensitive adhesive strength may decrease.

The acrylic pressure-sensitive adhesive composition according to the first invention comprises 0.1 to 5 parts by weight of an isocyanate-based crosslinking agent based on 100 parts by weight of the acrylic copolymer obtained above.

As the isocyanate-based crosslinking agent, 1
As long as it has two or more isocyanate groups in the molecule, it is not particularly limited, and examples thereof include diisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and hexamethylene diisocyanate; Isocyanate prepolymers obtained by reacting a polyol such as above with a diisocyanate as described above under the condition of an excess of isocyanate groups. One or more of these are preferably used. One or more isocyanate prepolymers in which the reaction proceeds mildly are more preferably used.

When the content of the isocyanate-based crosslinking agent is less than 0.1 part by weight based on 100 parts by weight of the acrylic copolymer, crosslinking of the resulting pressure-sensitive adhesive composition does not sufficiently proceed, and re-peelability and When the heat resistance becomes insufficient and the content of the isocyanate-based cross-linking agent exceeds 5 parts by weight, the cross-linking of the obtained pressure-sensitive adhesive composition proceeds excessively, and the tack decreases or the residual isocyanate group increases, The adhesion enhancement phenomenon over time becomes remarkable, and the removability is reduced.

The acrylic pressure-sensitive adhesive composition according to the second invention comprises 0.1 to 5 parts by weight of an organotin compound based on 100 parts by weight of the acrylic copolymer obtained above.

As the above-mentioned organotin compound, (c2)
Any material that can promote moisture crosslinking of the acrylic copolymer by the alkoxysilyl group contained in the component may be used,
Although not particularly limited, for example, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin diacetylacetonate and the like can be mentioned, and one or more of these are suitably used.

If the content of the organotin compound is less than 0.1 part by weight with respect to 100 parts by weight of the acrylic copolymer, crosslinking of the resulting pressure-sensitive adhesive composition will not sufficiently proceed, and removability and heat resistance will not occur. When the content becomes insufficient and the content of the organotin compound exceeds 5 parts by weight, bleed-out of the organotin compound is likely to occur, and tackiness and adhesive strength are reduced,
The adherend is easily contaminated. .

The degree of crosslinking of the acrylic pressure-sensitive adhesive composition according to the first or second invention is not particularly limited, but is preferably 50 to 85% by weight in terms of gel fraction, and is preferably 60 to 85% by weight. More preferably, it is 80% by weight. In addition, the gel fraction referred to here means "insoluble fraction (% by weight) in ethyl acetate of the dried film of the acrylic pressure-sensitive adhesive composition".

The acrylic viscosity according to the first or second invention
As for the adhesive composition, the dried film is measured by dynamic viscoelastic spectrum measurement.
Storage modulus at 120 ° C. is 2 × 10^Five
~ 7 × 10^Fivedyn / cm^Two, Preferably 3 × 10^Five~
6 × 10^Fivedyn / cm^Two, And at 120 ° C
Loss tangent (tan δ) in the range of 0.05 to 0.4,
Or 0.1-0.3, and stored at 0 ° C.
Storage modulus is 1 × 10^Five~ 4 × 10⁶dyn / cm^Two, Good
Preferably 5 × 10^Five~ 3 × 10⁶dyn / cm ^Two,
It is necessary to

The definitions of the storage elastic modulus and the loss tangent (tan δ) in the above dynamic viscoelastic spectrum measurement are as follows, for example:
"Introduction to Polymer Chemistry (Second Edition)" [edited by Okamura et al., Kagaku Dojinsha, p. 152 (1981)].

The measurement of the dynamic viscoelastic spectrum in the first invention or the second invention is performed by a shearing mode heating method at a frequency of 20 Hz under a condition of 0.5% strain.

In the above dynamic viscoelastic spectrum measurement,
The storage elastic modulus at 120 ° C. of the dried film of the acrylic pressure-sensitive adhesive composition according to the first or second invention is 2 × 10 ⁵ dyn.
If it is less than / cm ² , when left at high temperature for a long time, the pressure-sensitive adhesive composition will flow and tend to cause an increase in adhesion, resulting in a decrease in removability, and conversely, a storage modulus at 120 ° C. of 7 ×
If it exceeds 10 ⁵ dyn / cm ² , the wettability of the pressure-sensitive adhesive composition with respect to an adherend is reduced, so that tackiness and adhesion are insufficient.

In the above dynamic viscoelastic spectrum measurement, when the loss tangent (tan δ) at 120 ° C. of the dried film of the acrylic pressure-sensitive adhesive composition according to the first or second invention is less than 0.05, Since the wettability of the pressure-sensitive adhesive composition to an adherend is reduced, tack and adhesive strength become insufficient, and when the loss tangent (tan δ) at 120 ° C. exceeds 0.4, the composition is left at high temperature for a long time. In this case, the pressure-sensitive adhesive composition tends to flow to cause an adhesion enhancement phenomenon, and the removability is reduced.

Further, in the above dynamic viscoelasticity spectrum measurement, the storage elastic modulus at 0 ° C. of the dry film of the acrylic pressure-sensitive adhesive composition according to the first or second invention is 1 × 10 ⁵ d.
When it is less than yn / cm ² , the cohesive force of the pressure-sensitive adhesive composition becomes insufficient, so that the removability is reduced, and the storage elastic modulus at 0 ° C. exceeds 4 × 10 ⁶ dyn / cm ² . Then, since the elastic modulus of the pressure-sensitive adhesive composition in a low-temperature and short-time region corresponding to the time scale at the time of peeling increases, the deformation stress at the time of peeling also increases, and the re-peelability decreases.

The acrylic pressure-sensitive adhesive composition according to the first or second invention may contain, if necessary, a tackifying resin, a thickener, a thixotropic agent, a bulking agent, and a filler within a range that does not impair the achievement of the object of the present invention. One or more of various additives such as agents, softeners, plasticizers, surfactants, stabilizers, antioxidants, ultraviolet absorbers, and colorants may be contained.

The tackifying resin is not particularly limited, but examples thereof include rosin resins such as rosin and disproportionated rosin, modified rosin resins such as rosin ester and hydrogenated rosin ester, and terpene resins. , modified terpene resins, terpene phenol resins, hydrogenated terpene phenol resin, aromatic modified terpene resins, C ₅ petroleum resins, C
_Ninth petroleum resin, aliphatic hydrocarbon resin, alicyclic hydrocarbon resin, aromatic hydrocarbon resin, coumarone indene resin, etc., and one or more of these are preferably used. Among them, one or more of disproportionated rosin, a hydrogenated terpene phenol resin, an alicyclic hydrocarbon-based resin and the like having a large initial tackiness improving effect are more preferably used.

Examples of the thickener include, but are not particularly limited to, elastomers such as acrylic rubber, epichlorohydrin rubber, isoprene rubber, and butyl rubber. One or more of these are preferably used. Can be

The thixotropic agent is not particularly restricted but includes, for example, colloidal silica, polyvinylpyrrolidone and the like.
More than one species is preferably used.

The extender is not particularly restricted but includes, for example, calcium carbonate, titanium oxide, clay, talc and the like, and one or more of these are preferably used.

Examples of the filler include inorganic hollow bodies such as glass balloons, alumina balloons and ceramic balloons; organic hollow bodies such as vinylidene chloride balloons and acrylic balloons; organic spherical bodies such as nylon beads, acrylic beads and silicone beads; Single fibers such as rayon and nylon are exemplified, and one or more of these are suitably used.

Next, the pressure-sensitive adhesive product according to the third invention is characterized in that the acrylic pressure-sensitive adhesive composition according to the first or second invention is applied to at least one surface of a substrate. The term "adhesive product" used herein is not particularly limited, and includes various adhesive products such as an adhesive tape, a foam tape, an adhesive sheet, an adhesive label, a surface protective film or a sheet.

The above-mentioned pressure-sensitive adhesive product may be a single-sided pressure-sensitive adhesive product in which the pressure-sensitive adhesive composition is coated on only one side of the substrate, such as a single-sided pressure-sensitive adhesive tape, or a substrate, such as a double-sided pressure-sensitive adhesive tape. It may be a double-sided pressure-sensitive adhesive product having a pressure-sensitive adhesive composition applied to both sides.

Further, after applying the pressure-sensitive adhesive composition to the release surface of a substrate having release properties, such as release paper or a release film,
A so-called non-support type single-sided or double-sided adhesive processed product which is finally obtained by removing the substrate having a releasing property may be used.

Further, in any of the above cases, a pressure-sensitive adhesive product in which one kind of pressure-sensitive adhesive composition is coated in a single layer or a plurality of layers may be used, or two or more kinds of pressure-sensitive adhesive compositions may be coated in a plurality of layers. The processed adhesive product may be used.

Further, in the case of a double-sided pressure-sensitive adhesive processed product, the pressure-sensitive adhesive compositions applied to the respective surfaces may have the same composition or different compositions.

The type of the substrate used in the third invention is not particularly limited, and examples thereof include various films such as cellophane, polyethylene, polypropylene, polyester, and polystyrene; various nonwoven fabrics such as rayon and cellulose. Various plastic foams such as polyethylene foam, polypropylene foam and polyurethane foam; various rubber foams such as natural rubber foam, styrene-butadiene rubber foam, chloroprene rubber foam, acrylonitrile-butadiene rubber foam and the like. And
It is preferably used. When a non-support type pressure-sensitive adhesive product is produced, a substrate having release properties on one or both sides, such as release paper or a release film, is preferably used.

When a pressure-sensitive adhesive product is produced using the above-mentioned substrate, the pressure-sensitive adhesive composition is coated to further enhance the adhesion of the acrylic pressure-sensitive adhesive composition according to the first or second invention to the substrate. The substrate surface to be coated (coated surface) may be subjected to a surface treatment such as corona discharge treatment or primer coating in advance, or the acrylic pressure-sensitive adhesive composition according to the first or second invention may be coated. In order to enhance the releasability (developability) of the pressure-sensitive adhesive composition from the non-coated base material surface (non-coated surface), the non-coated surface of the base material may be subjected to a release treatment in advance.

The method for applying the acrylic pressure-sensitive adhesive composition according to the first or second invention to the substrate is not particularly limited, and examples thereof include a roll coater, a bar coater, a flow coater, a spray coater, and a doctor blade. What is necessary is just to perform using the normally used coating apparatus, such as.

The coating thickness of the acrylic pressure-sensitive adhesive composition according to the first or second invention on the surface of the base material may be appropriately set according to the use and purpose of use of the pressure-sensitive adhesive product, and is particularly limited. Although not to be performed, generally, the thickness of the pressure-sensitive adhesive composition on one side of the substrate after drying is 10 to 20
It is preferably about 0 μm.

[0061]

The acrylic pressure-sensitive adhesive composition according to the first invention is characterized in that an acrylic copolymer obtained from a monomer component containing a specific amount of a specific monomer is appropriately crosslinked with a specific amount of an isocyanate crosslinker, and , 12 of the dried film
Since the storage elastic modulus and the loss tangent (tan δ) at 0 ° C. and the storage elastic modulus at 0 ° C. are set to be in specific ranges, high performance with excellent balance between tack and adhesion and cohesion. Pressure-sensitive adhesive composition, and even when used under harsh conditions such as construction sites, even when used on adherends with low surface strength such as paper,
It is suitable for obtaining a pressure-sensitive adhesive product exhibiting excellent re-peelability, with almost no increase in adhesion over time.

The acrylic pressure-sensitive adhesive composition according to the second aspect of the present invention is characterized in that an acrylic copolymer obtained from a monomer component containing a specific amount of a specific monomer is appropriately crosslinked using a specific amount of an organotin compound as a crosslinking accelerator. Storage modulus and loss tangent (t) of the dried film at 120 ° C.
anδ), and the storage elastic modulus at 0 ° C. is set so as to be in a specific range, so that it is a high-performance pressure-sensitive adhesive composition having an excellent balance between tack and tackiness and cohesion. Even when used under harsh conditions such as construction sites, or when used on adherends with low surface strength, such as paper, there is almost no increase in adhesion over time, demonstrating excellent removability. It is suitable for obtaining an adhesive processed product.

Further, the pressure-sensitive adhesive product according to the third invention is:
Since it is produced using the acrylic pressure-sensitive adhesive composition according to the first invention or the second invention, it has both excellent adhesive performance and removability.

[0064]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In the examples, “parts” means “parts by weight”, and “%” means “% by weight” unless otherwise specified.

(Example 1)

(1) Polymerization of Acrylic Copolymer In a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a dropping funnel, n-butyl acrylate 9 as a component (a) was added.
9 parts, 1 part of 2-hydroxyethyl methacrylate as the component (c1) and 81.8 parts of ethyl acetate as a solvent were charged, and the mixture was heated to reflux for 30 minutes. Then, benzoyl peroxide 0.1 as a radical polymerization initiator was added. Was added and reacted for 7 hours. Further, 0.1 part of benzoyl peroxide was added and reacted for 3 hours. At the second, fourth, and seventh hours after the start of the reaction, 20 parts of ethyl acetate was added for each dilution. Then, toluene 8
After adding 0 parts, the mixture was cooled to obtain an acrylic copolymer solution having a solid content of 31%.

(2) Preparation of acrylic pressure-sensitive adhesive composition The solid content of the acrylic copolymer solution obtained above was 100%.
To the parts, 2 parts of solid content of “Coronate L-45” (solid content: 45%, manufactured by Nippon Polyurethane Industry Co., Ltd.) was added as an isocyanate-based cross-linking agent, and the mixture was uniformly stirred and mixed. I got

(3) Preparation of pressure-sensitive adhesive tape The acrylic pressure-sensitive adhesive composition obtained above was coated on a 38 μm-thick polyethylene terephthalate film so that the film thickness after drying was 20 μm, and then heated at 80 ° C. For 3 minutes. Then, release paper is stuck,
After curing for one week in an atmosphere of 20 ° C. and 65% RH, the sheet was cut to a width of 25 mm to obtain a single-sided adhesive tape.

(4) Characteristic evaluation of acrylic pressure-sensitive adhesive composition The characteristics (measurement of dynamic viscoelastic spectrum, gel fraction) of the acrylic pressure-sensitive adhesive composition obtained in (2) were evaluated by the following methods. . The results were as shown in Table 1.
The evaluation was performed at 20 ° C.-65% RH unless otherwise specified.
Performed under the atmosphere of

Measurement of Dynamic Viscoelastic Spectrum The acrylic pressure-sensitive adhesive composition was applied to the release surface of release paper, and dried in an oven at 80 ° C. for 3 minutes. Then
An adhesive composition sheet having a film thickness of about 1 mm was formed by lamination, and the sheet was cured under an atmosphere of 20 ° C. and 65% RH for one week to obtain a sample for dynamic viscoelasticity spectrum measurement.

The dynamic viscoelastic spectrum of the sample obtained above was measured using a dynamic viscoelasticity measuring apparatus (model “itk DVA-20”).
0 "(manufactured by IT Measurement Control Co., Ltd.) under the following conditions, and the storage elastic modulus at 120 ° C. (dyn / cm ² )
And the loss tangent (tan δ) and the storage modulus at 0 ° C. (dyn / cm ² ) were determined. [Measurement conditions] Deformation mode: shearing method, heating rate: 3 ° C /
Minute, frequency: 20 Hz, distortion: 0.5%

After precisely weighing about 0.5 g of the pressure-sensitive adhesive composition sheet prepared in accordance with the gel fraction, the sheet was immersed in about 100 g of ethyl acetate and shaken at 20 ° C. for 2 days. Next, the insoluble matter was filtered off with a 100-mesh stainless steel wire gauze and dried. After that, the weight of the insoluble matter was precisely weighed, and the gel fraction (%) was determined by the following formula.

(5) Evaluation of Performance of Adhesive Tape The performance (adhesive strength, removability) of the adhesive tape obtained in (3) was evaluated by the following method. The results were as shown in Table 1. The evaluation was 2 unless otherwise stated.
The test was performed in an atmosphere of 0 ° C. and 65% RH.

Adhesive Strength A stainless steel plate (1.5 mm thick) in accordance with JIS Z-0237 “Testing method for adhesive tape / adhesive sheet”
And a 180-degree angle peel strength (g / 25 mm) after curing in an atmosphere of 20 ° C. for 30 minutes as an initial adhesive force, and curing for one week in an atmosphere of 50 ° C. as an adhesive force with time. 180 degree peel strength (g /
25 mm). The tensile speed at the time of measurement was 300
mm / min.

Removability After adhering an adhesive tape to high quality paper, 2 kg / 900
The cells were cured under an atmosphere of 50 ° C. for 1 week by applying a pressure of ² cm ² . Next, the adhesive tape was peeled off by hand, and the presence or absence of paper tear was visually observed.

(Examples 2 to 4 and Comparative Examples 1 to 6) The polymerization composition of the acrylic copolymer was set to the composition shown in Table 1, and the amount of the solid content of the isocyanate crosslinking agent "Coronate L-45" was added. In the same manner as in Example 1 except that the amounts shown in Table 1 were used, nine types of acrylic copolymer solutions, acrylic pressure-sensitive adhesive compositions, and pressure-sensitive adhesive tapes were obtained.

The properties of the nine types of acrylic pressure-sensitive adhesive compositions obtained above and the performance of nine types of pressure-sensitive adhesive tapes were evaluated in the same manner as in Example 1. The results were as shown in Table 1.

[0078]

[Table 1]

As is clear from Table 1, the pressure-sensitive adhesive tapes of Examples 1 to 4 according to the first invention have excellent initial pressure-sensitive adhesive strength and improved adhesive strength after curing at 50 ° C. for one week (adhesion). (Repeated phenomenon), and exhibited excellent removability even when applied to an adherend having a low surface strength such as paper.

On the other hand, when the content of the component (b) is 0.0
The pressure-sensitive adhesive tape of Comparative Example 1 produced using an acrylic pressure-sensitive adhesive composition obtained by copolymerizing a monomer component exceeding 01% by weight, and having a storage elastic modulus at 120 ° C. of 2 × 10 ⁵
dyn / cm ² , the loss tangent (tan δ) of the pressure-sensitive adhesive tape of Comparative Example 2 or Comparative Example 6 produced using the acrylic pressure-sensitive adhesive composition exceeding 0.4,
Since the initial adhesive strength was too high and the adhesive strength after aging (adhesion enhancement phenomenon) was large, the removability was poor.

Further, the pressure-sensitive adhesive tape of Comparative Example 3 produced using an acrylic pressure-sensitive adhesive composition obtained by copolymerizing a monomer component having a component (c1) content of more than 5% by weight,
Using an acrylic pressure-sensitive adhesive composition obtained by copolymerizing a monomer component having a component (d1) content of more than 20% by weight and having a storage elastic modulus at 0 ° C. of more than 4 × 10 ⁶ dyn / cm ^2. Pressure-sensitive adhesive tape of Comparative Example 4 or an acrylic pressure-sensitive adhesive in which the solids content of the isocyanate-based cross-linking agent (Coronate L-45) exceeds 5 parts by weight based on 100 parts by weight of the acrylic copolymer Although the adhesive tape of Comparative Example 5 produced using the composition had good re-peelability, the adhesive strength was extremely low both in the initial stage and after the elapse of time, and functioned as an adhesive tape. Did not.

Example 5 A four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a dropping funnel was charged with 98 parts of n-butyl acrylate as the component (a) and 3-triacrylic acid as the component (c2). 2 parts of methoxysilylpropyl and 81.8 parts of ethyl acetate as a solvent were charged, and the temperature was increased to 3 parts.
After refluxing for 0 minutes, 0.1 part of benzoyl peroxide was added as a radical polymerization initiator and reacted for 7 hours, and 0.1 part of benzoyl peroxide was further added and reacted for 3 hours. At the second, fourth, and seventh hours after the start of the reaction, 20 parts of ethyl acetate was added for each dilution. Then, after adding 80 parts of toluene,
Upon cooling, an acrylic copolymer solution having a solid content of 31% was obtained.

To 100 parts of the solid content of the acrylic copolymer solution obtained above, 2 parts of a solid content of dibutyltin dilaurate as an organic tin compound was added, and the mixture was stirred and mixed uniformly to obtain an acrylic pressure-sensitive adhesive composition. I got

Next, a single-sided pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 using the acrylic pressure-sensitive adhesive composition obtained above.

The properties (measurement of dynamic viscoelastic spectrum, gel fraction) of the acrylic pressure-sensitive adhesive composition obtained above,
And, the performance (adhesive strength,
(Removability) was evaluated in the same manner as in Example 1. The results were as shown in Table 2.

(Examples 6 and 8, and Comparative Examples 7 and 12)
The polymerization composition of the acrylic copolymer is the composition shown in Table 2,
Nine types of acrylic copolymer solutions and acrylic pressure-sensitive adhesive compositions were prepared in the same manner as in Example 5 except that the amount of the solid content of the organotin compound (dibutyltin dilaurate) was changed to the amount shown in Table 2. Obtained. Next, nine kinds of single-sided pressure-sensitive adhesive tapes were obtained in the same manner as in Example 1 using the acrylic pressure-sensitive adhesive composition obtained above.

The properties of the nine kinds of acrylic pressure-sensitive adhesive compositions obtained above and the performance of nine kinds of pressure-sensitive adhesive tapes were evaluated in the same manner as in Example 1. The results were as shown in Table 2.

[0088]

[Table 2]

As is evident from Table 2, the pressure-sensitive adhesive tapes of Examples 5 to 8 according to the second invention have excellent initial pressure-sensitive adhesive strength and improved adhesive strength after curing at 50 ° C. for one week (adhesion). (Repeated phenomenon), and exhibited excellent removability even when applied to an adherend having a low surface strength such as paper.

On the other hand, when the content of the component (b) is 0.0
A pressure-sensitive adhesive tape of Comparative Example 7, produced using an acrylic pressure-sensitive adhesive composition obtained by copolymerizing a monomer component exceeding 01% by weight, having a storage elastic modulus at 120 ° C. of 2 × 10 ⁵
The pressure-sensitive adhesive tape of Comparative Example 8 or Comparative Example 10 manufactured using an acrylic pressure-sensitive adhesive composition having a dtang / cm ^{2 of} less than 0.4 and a loss tangent (tan δ) of more than 0.4 has an initial adhesive strength. Was too high, and the improvement of the adhesive force after a lapse of time (adhesion enhancement phenomenon) was large, so that the removability was poor.

The pressure-sensitive adhesive tape of Comparative Example 11, which was produced using an acrylic pressure-sensitive adhesive composition not containing an organotin compound (dibutyltin dilaurate) as a crosslinking accelerator, was prepared in either the initial state or after aging. Also, the cohesive force of the pressure-sensitive adhesive layer was extremely low, and the removability was poor.

Further, the pressure-sensitive adhesive tape of Comparative Example 9 produced using an acrylic pressure-sensitive adhesive composition obtained by copolymerizing a monomer component having a component (d2) content of more than 20% by weight, or Comparative Example 12 produced using an acrylic pressure-sensitive adhesive composition having a solid content of an organotin compound (dibutyltin dilaurate) as a crosslinking accelerator of more than 5 parts by weight per 100 parts by weight of an acrylic copolymer Each of the pressure-sensitive adhesive tapes had good removability, but the adhesive strength was extremely low both at the initial stage and after aging, and did not function as an adhesive tape.

[0093]

As described above, the acrylic pressure-sensitive adhesive composition according to the first or second invention exhibits excellent adhesive strength both in the initial stage and after the elapse of time, and has a long lasting condition under severe conditions. Even when left for a long period of time, the adhesion promotion phenomenon is less likely to occur and the removability is excellent.

Further, since the pressure-sensitive adhesive product according to the third invention is manufactured using the acrylic pressure-sensitive adhesive composition according to the first or second invention, it has excellent adhesive performance and removability. Yes, it is suitably used for various uses such as stationery, packaging, building materials, home appliances and the like.

Claims (3)

[Claims] 1. The following component (a): 74.999 to 99.9
0 to 0.001% by weight of the following component (b), 0.1 to 5% by weight of the following component (c1) and 0 of the following component (d1)
100 parts by weight of an acrylic copolymer obtained by radical copolymerization of a monomer component containing 20 to 20% by weight,
An acrylic pressure-sensitive adhesive composition containing 0.1 to 5 parts by weight of an isocyanate-based cross-linking agent, wherein the pressure-sensitive adhesive composition has a dry film of 120 in a dynamic viscoelasticity spectrum measurement.
Storage elastic modulus at 2 ° C. is 2 × 10 ^{5 to} 7 × 10 ⁵ dyn / c
m ² and loss tangent (tan δ) are 0.05 to 0.4, and storage elastic modulus at 0 ° C. is 1 × 10 ⁵ to 4 × 10
An acrylic pressure-sensitive adhesive composition having a dyn / cm ² of ⁶ dyn / cm ² . Component (a): alkyl (meth) acrylate monomer (b) Component: carboxyl group-containing monomer copolymerizable with component (a) Component (c1): hydroxyl-containing monomer copolymerizable with component (a) Component (d1): a monomer other than the component (b) and the component (c1), which is copolymerizable with the component (a) 2. The following component (a): 74.999 to 99.9
0 to 0.001% by weight of the following component (b), 0.1 to 5% by weight of the following component (c2) and 0 of the following component (d2)
100 parts by weight of an acrylic copolymer obtained by radical copolymerization of a monomer component containing 20 to 20% by weight,
An acrylic pressure-sensitive adhesive composition containing 0.1 to 5 parts by weight of an organotin compound, wherein the storage elastic modulus at 120 ° C. in dynamic viscoelastic spectrum measurement of a dried film of the pressure-sensitive adhesive composition is 2 × 10 ^{5 to} 7 × 10 ⁵ dyn / cm ² and a loss tangent (tan δ) of 0.05 to 0.4; and
The storage elastic modulus at 0 ° C. is 1 × 10 ⁵ to 4 × 10 ⁶ dyn /
acrylic pressure-sensitive adhesive composition which is a cm ^2. Component (a): alkyl (meth) acrylate monomer (b) Component: carboxyl group-containing monomer copolymerizable with component (a) Component (c2): alkoxysilyl group copolymerizable with component (a) Contained monomer (d2) component: a monomer copolymerizable with component (a) other than component (b) and component (c2) 3. A pressure-sensitive adhesive product, wherein the acrylic pressure-sensitive adhesive composition according to claim 1 or 2 is applied to at least one surface of a substrate.