JPS60202175A - Pressure-sensitive adhesive composition and adhesive tape or sheet thereof - Google Patents

Abstract

PURPOSE:To provide the titled compsn. which has well-balanced properties between cohesive force, tack and viscoelasticity and does not cause gelling with time, consisting of two kinds of copolymers mainly composed of an alkyl (meth) acrylate and a polyfunctional compd. CONSTITUTION:1-4pts.wt. copolymer (A) composed of 70-99.9mol% of an alkyl (meth)acrylate (a) (e.g. butyl acrylate) and 0.1-20mol% of a polymerizable monomer (b) contg. a reactive functional group (X) (e.g. 2-hydroxyethyl methacrylate), 4-1pts.wt. (co)polymer (B) composed of at least 70mol% of component (a) and not more than 30mol% of a polymerizable monomer (c) contg. neither the group X nor other functional group reactive with the group X, and a polyfunctional compd. (C) contg. two or less functional groups (Y) reactive with the group X (e.g. 2,4-tolylene diisocyanate) in an equal quantity to that of the group X, are mixed together to obtain the title compsn. The compsn. is laminated on at least one side of a substrate to obtain the titled tape or sheet.

Description

[Detailed description of the invention] Related to adhesive tape and sheet.

[Prior art]

Conventionally, pressure-sensitive adhesives include so-called rubber-based pressure-sensitive adhesives that are mainly made of natural rubber or synthetic rubber, mixed with a tackifying resin, a softening agent, filler #J, etc., and acrylic ester as the main ingredient. BACKGROUND ART Acrylic pressure-sensitive adhesives, which are copolymerized with polar monomers such as acrylic acid, are widely used in packaging, stationery, medical, and other industrial applications.

Among these, rubber-based pressure-sensitive adhesives have the convenience of being able to adhere to a relatively large number of adherends, but they also have durability (weather resistance, heat resistance, It has the disadvantage that it has poor VC and cannot be used in the field of permanent or semi-permanent adhesives.

On the other hand, acrylic pressure-sensitive adhesives have been used in an increasing number of applications in recent years due to their excellent weather resistance. However, in the case of acrylic pressure-sensitive adhesives, the weight average molecular weight has to be limited to 10' or less due to problems in conventional polymerization technology and coating technology. In this way, it is possible to obtain books with excellent tackiness and adhesion using acrylic pressure-sensitive adhesives, but only very poor holding or cohesive strength can be obtained.

As a means to compensate for this lack of cohesive force, compositions with a crosslinked structure have been investigated, and various crosslinked acrylic pressure-sensitive adhesives have been proposed.

For example, in Japanese Patent Application Laid-open No. 56-95965, 1 Lukil (
A pressure-sensitive adhesive composition comprising a copolymer (Al) of meth)acrylate and hydroxyalkyl (meth)acrylate, a copolymer (Bl) of alkyl (meth)acrylate and (meth)acrylic acid, and a polyfunctional incyanate compound. Are listed.

However, this pressure-sensitive adhesive composition is based on a copolymer (Al
Since both the and (Bl) are crosslinked by isocyanate compounds, the cohesive force tends to increase and the adhesive force and viscoelasticity tend to decrease, making it difficult to maintain the balance, and the gel fraction increases over time. there were.

[Purpose of the invention]

In view of the above-mentioned drawbacks, the object of the present invention is to provide a pressure-sensitive adhesive composition and a pressure-sensitive adhesive tape that have excellent cohesive force, adhesive force, and viscoelasticity, and which, if well-balanced, will not gel over time. It would be helpful if you could provide a cover sheet.

[Structure of the Invention] The gist of the present invention is a co-electropolymer mainly composed of alkyl (meth)acrylate and a polymerizable monomer having a reactive functional group (Xl), (Bl mainly composed of alkyl (meth)acrylate 2) ,
Reactive functional group (X) and the functional group fX),! - A polymer or a copolymer having no other reactive functional group, and (C) a functional group (Yl) that reacts with the reactive functional group (X).
and (A) a polymerizable monomer mainly composed of alkyl (meth)acrylate and having a reactive functional group (X). copolymer, (B) a polymer or copolymer mainly composed of alkyl (meth)acrylate and containing a reactive functional group (X) and other functional groups that react with the functional group (Xl), and (Pressure-sensitive adhesive in which the copolymer is crosslinked due to the polyfunctional compound (C) K, which is not a polyfunctional compound having at least two functional groups (Y) that can react with the C1 reactive functional group (X)) The present invention also includes a pressure-sensitive adhesive tape and a structure sheet characterized in that an agent layer is laminated on at least one surface of a base material.

Among the alkyl (meth)acrylates used in the present invention, alkyl acrylates and alkyl methacrylates preferably have an alkyl group having 4 to 18 carbon atoms, such as n-butyl acrylate, 1so-butyl acrylate, ter-butyl acrylate, etc. Acrylate, 1so-
amyl acrylate, 2-ethylhexyl acrylate,
Examples include i-octyl acrylate, lacryl acrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, lacryl acrylate, and the like. Among these, n-butyl acrylate, 1so-amyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, n-
One or more monomers selected from the group of octyl methacrylate and lacryl methacrylate are more preferably used. .

The polymerizable monomer used in the present invention has a reactive functional group (X
A monomer having a functional group (Xl is preferably a functional group selected from the group consisting of a carboxyl group, a citroxyl group, an epoxy group, an acid anhydride group, and an amide group, such as acrylic acid, methacrylic acid, Acid, β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, polyethylene glycol acrylate, polyethylene glycol methacrylate, polypropylene glycol acrylate, polypropylene glycol methacrylate, glycidyl acrylate, maleic anhydride, acrylamide, methacrylic Examples include amides.

Copolymer in the present invention (Al is the above-mentioned alkyl)
It is a copolymer mainly composed of acrylate and the above polymerizable monomer, and since the alkyl (meth)acrylate in the copolymer (A) imparts adhesiveness, the content is 70 to 9.
The content of the polymerizable monomer is preferably 9.9 mol %, and if the content of the polymerizable monomer is too small, the crosslinked IIIK will not be able to exhibit sufficient cohesive force, whereas if it is too large, the crosslinking density will increase and the adhesiveness will decrease. Therefore, it is preferably 0.1 to 20 mol%, more preferably 0.5 to 5 mol%.

In addition, even if the above copolymer (Al is copolymerized with a reactive functional group (Xl) and a polymerizable monomer that does not have other functional groups that can react with the functional group (Xl) in a range of 29.9 mol% or less Examples of the polymerizable monomer include aromatic acrylates such as benzyl acrylate, benzyl methacrylate, and phenoxyethyl acrylate, styrene, and vinyl acetate.

The polymer or copolymer (B) in the present invention is mainly composed of alkyl (meth)acrylate, and the reactive functional group (X
1 and does not have other functional groups that can react with the functional group (X), and since the adhesiveness decreases when the content of alkyl (meth)acrylate decreases, the content of alkyl (meth)acrylate The amount is preferably 70 mol% or more, and the reactive functional group (X) and the polymerizable monomer having no other functional group that reacts with the functional group (Xl) are copolymerized within a range of 30 mol% or less. may be done.

The above copolymer (Al and polymer copolymer (B)
Any known method may be adopted as the polymerization method, and solution polymerization using an organic peroxide, an azo polymerization initiator, etc. in an organic solvent such as ethyl acetate, toluene, acetone, methyl ethyl ketone, or cyclohexane is preferred. preferable.

The polyfunctional compound used in the present invention (C1 is a compound having at least two functional groups (Yl) that can react with the reactive functional group (X), and the functional group (Y) is, for example, an isocyanate group, an amino acid group, etc. 7 groups, metal ions, etc., and the polyfunctional compound is preferably a compound selected from the group consisting of incyanate compounds, amine compounds, and alkali metals, such as 2.4) lylene diisocyanate, methylene Bisphenyl isocyanate, trimethylolpropane tolylene diisocyanate,
Examples include trimethylolpropane triincyanate, hexamethylene diamine, calcitam, magnesium, and zinc.

It is a copolymer (aluminum and polymer is also a copolymer (
The ratio of Bl is (as the ratio of Al increases, the ratio of crosslinkable copolymer increases, making it difficult to control the crosslinking rate, decreasing storage stability, and increasing the ratio of inverse K (B). If it becomes too large, sufficient cohesive force cannot be obtained even if cross-linked, so 1
It is preferable that the ratio is 4 to 4:1. Also, polyfunctional compounds (
If the amount of C1 added is too large, free polyfunctional compound tc
The presence of + decreases the adhesive properties, and when it decreases, the crosslinking density decreases and sufficient cohesive force cannot be obtained. It is preferable to add approximately equivalent amount.

The pressure-sensitive adhesive tape or mechanism sheet of the present invention has a pressure-sensitive adhesive layer formed by crosslinking the above-mentioned pressure-sensitive adhesive composition laminated on at least one surface of a base material, and the above-mentioned base material is optional. Can be used, such as polyester,
Examples include films of polycarbonate, cellophane, cellulose triacetate, polyether kerfone, polymethyl methacrylate, and the like.

Further, the crosslinking of the pressure sensitive adhesive layer is carried out at the same time as the pressure sensitive adhesive composition is applied to the base material Klj and the solvent etc. are volatilized, but in order to ensure crosslinking, one heat curing may be performed.

In addition, when crosslinking density decreases, cohesive force is insufficient, adhesive strength decreases, and creep properties worsen; conversely, when crosslinking density decreases, it becomes hard, wettability decreases, and adhesive strength decreases, so the gel fraction is preferably 15 to 60%.

The glue here is immersed in ethyl acetate at 20℃,
This is the weight fraction of the insoluble portion after 72 hours of extraction. .

Furthermore, if the saturated gel fraction in the copolymer is GA, and the gel fraction/copolymer (A) blending ratio in the pressure-sensitive adhesive layer is GAB, then as the value of GAB/GA becomes smaller, the copolymer (A) )
Since the effect of mixing the polymer and the copolymer (B) is reduced, the value of GAB/GA is preferably α6 or more, more preferably a7 to LO. .

The saturated gel fraction GA is a copolymer (by adding an excess polyfunctional compound to AIK,
It refers to the gel fraction when reacting and crosslinking.

Further, any method may be used for producing the pressure-sensitive adhesive tape or the structure sheet of the present invention, such as applying a solution-polymerized pressure-sensitive adhesive composition onto a tape base using a roll coater.
A pressure-sensitive adhesive tape can be obtained by coating the adhesive using a knife caulk or the like so that the solid content is several tens of μm and several hundred P, and then evaporating the solvent with hot air.

〔Effect of the invention〕

Since the composition of the pressure-sensitive adhesive composition and the pressure-sensitive adhesive tape and the structure sheet of the present invention are as described above, the adhesive after crosslinking contains the crosslinked gel-like copolymer (A) and the uncrosslinked sol-like copolymer (A). The copolymer (B) and the copolymer (B) coexist, and the cohesive force, adhesive force, and viscoelasticity are excellent and well-balanced. It is easy to use, and does not gel over time and its physical properties do not deteriorate.

〔Example〕

Next, the present invention will be explained in detail.

Examples 1 to 6, Comparative Example The nine compositions shown in Table 1 were put into an anti-FI5 vessel equipped with a stirrer, a cooler, a temperature controller, and a nitrogen introduction device, and the oxygen in the reactor was removed by a nitrogen stream. After expelling, the reactor was heated to 60
The mixture was heated to .degree. C. and polymerized for 15 hours under a nitrogen stream to obtain a copolymer solution.

In addition, 500y of ethyl acetate was added at 3 hours and 6 hours after the start of polymerization, and 100g of ethyl acetate was added at 10 hours.
, y and azobisisobutyronitrile 3F were added, and then the temperature was raised until ethyl acetate refluxed.

Furthermore, ethyl acetate was added to the obtained copolymer solution to obtain adhesives A and B having a solid content of 15%.

Table 1 Next, use adhesives A and B in the ratio shown in Table 2 with a solid content of 100.
PK, mix both uniformly, and add a predetermined amount of trimethylolpro/pro/as a crosslinking agent shown in Table 2
A pressure sensitive adhesive composition solution was obtained by adding p-triisocyanate.

Next, the above pressure-sensitive adhesive composition solution was applied onto one side of a 25p thick polyester film that had been subjected to silicone mold release treatment so that the glue thickness was 30P, dried at 80°C for 20 minutes, and then crosslinked. A pressure-sensitive adhesive tape was obtained by transferring the mixture onto a cellulose triacetate film having a thickness of 80/A.

The peeling force and pole tack of the obtained adhesive tape were measured and the results are shown in Table 2. In addition, the gel fraction and GAB/GA values of the adhesive layer of the adhesive tape were measured and shown in Table 2.

The measurement method is as follows.

(l The peeling force is determined by pasting an adhesive tape with a width of 15M on a glass plate, pressing it with the 2 o'clock roll back and forth 5 times, leaving it for 15 minutes, and then peeling it off at a speed of 300ffZ at an angle of 180 degrees. It shows the strength when it is applied, and it shows the adhesive force and cohesive force.

The unit is y/15 drunkenness.

(2) Ball tack is based on the J-DOW method and represents adhesive strength. The unit is 1732 inches.

(3) Saturated gel fraction was determined by adding 2% by weight of trimethylolpropane tolylene diisocyanate and 0.05% by weight of digyltin silacrate based on the solid content of Adhesives AK and Adhesive A, and heating at 50°C for 5 days. Measurements were taken after curing. 85
%Met,.

Table 2

Claims (1)

[Scope of Claims] LiA) A copolymer mainly composed of alkyl (meth)acrylate and a polymerizable monomer having a reactive functional group (X); (B) A copolymer mainly composed of alkyl (meth)acrylate and having a reactive functional group (X); A polymer or copolymer that does not have a functional group (X) and other functional groups that can react with the functional group (X), and (C) a functional group (Y) that can react with the reactive functional group (X). )
A pressure-sensitive adhesive composition comprising a polyfunctional compound having at least two. 2. The pressure-sensitive adhesive according to claim 1, wherein the reactive functional group (X) is a functional group selected from the group consisting of a carboxyl group, a hydroxyl group, an epoxy group, an acid anhydride group, and an amide group. Composition. 3. Claim 1, wherein the content of alkyl (meth)acrylate in the copolymer (A) is 70 to 99.9 mol%, and the content of the polymerizable monomer is α1 to 20 mol%. Or the pressure-sensitive adhesive composition according to item 2. Table: Pressure-sensitive adhesive according to claim 1, 2, or 3, wherein the copolymer (Al and the polymer copolymer (B) have a mixing ratio of 1=4 to 4:1) Agent composition. 5. Polyfunctional compound (C1 is a compound selected from the group consisting of incyanate compounds, amine compounds, and alkali metals) according to any one of claims 1 to 4. A pressure-sensitive adhesive composition. a (A) a copolymer mainly composed of an alkyl (meth)acrylate and a polymerizable monomer having a reactive functional group (X); (B) a copolymer mainly composed of an alkyl (meth)acrylate; , a polymer or copolymer that does not have a reactive functional group (X) and other functional groups that can react with the functional group '(X), and (C) a reactive functional group (that can react with Functional group (Y)
A copolymer (A
1. A pressure-sensitive adhesive tape-based sheet, characterized in that a cross-linked pressure-sensitive adhesive layer is laminated on at least one surface of a base material. 7. The pressure-sensitive adhesive tape according to claim vJ6, wherein the reactive functional group (X) is a functional group selected from the group consisting of a carboxyl group, a hydroxyl group, an epoxy group, an acid anhydride group, and an amide group. Or a sheet. a Copolymer (in Al, the content of alkyl (meth)acrylate is 70 to 99.9 mol%, and the content of polymerizable monomer is 0.1 to 20 mol%) Claim 6 or the pressure-sensitive adhesive tape and sheet according to item 7. 9. Copolymer (Al and polymer 1 polymer or copolymer (B)
The pressure-sensitive adhesive tape or sheet according to claim 6, 7 or 8, wherein the mixing ratio of l is 1=4 to 4:1. The pressure-sensitive adhesive tape according to any one of claims 6 to 9, wherein the IQ polyfunctional compound fc) is a compound selected from the group consisting of isocyanate compounds, amine compounds, and alkali metals. Bake sheet 1) IL Pressure-sensitive adhesive frame i & gel fraction is 15-60%
A pressure-sensitive adhesive tape and sheet according to any one of claims 6 to 10.