JP5151982B2 - Pressure sensitive adhesive and pressure sensitive adhesive film - Google Patents

Description

  The present invention relates to a pressure-sensitive adhesive and a pressure-sensitive adhesive film using the pressure-sensitive adhesive. Specifically, the present invention relates to a pressure-sensitive adhesive that is suitably used when an optical film is attached to an adherend such as glass. More specifically, a pressure-sensitive type that can form a pressure-sensitive adhesive film (pressure-sensitive adhesive film) that can be peeled off without being contaminated even when placed under high temperature, high pressure, high temperature, and high temperature and high humidity after sticking. It relates to adhesives.

In recent years, display devices have been used in household and commercial appliances such as electronic computers, electronic watches, mobile phones, and televisions, equipment mounted on vehicles, etc., and have many opportunities to be used under various harsh conditions. It has become. Various optical films such as a polarizing film and a retardation film are used for display members constituting these display devices.
Various optical films such as a polarizing film and a retardation film are attached to glass or another optical film as an adherend using a pressure-sensitive adhesive. Once a defect is found in the adhesion state after being adhered to the adherend, the polarizing film or retardation film is peeled off from the glass or the like, and a new polarizing film or retardation film is adhered. This re-pasting operation is called “rework”. At the time of reworking, it is required that the pressure-sensitive adhesive layer does not remain on the adherend surface.

  By the way, a polarizing film is a thing of the structure by which the stretched polyvinyl alcohol film dye | stained with the pigment | dye was pinched | interposed with the triacetyl cellulose type protective film or the cycloolefin type protective film. Polarizing films have poor dimensional stability due to the properties of these materials, and the dimensional change due to film shrinkage is particularly severe under high temperature or high temperature and high humidity conditions.

When a laminate composed of an optical film / pressure-sensitive adhesive layer / adherent is placed under high temperature or high temperature / humidity conditions and the dimensions of the optical film change, the interface between the pressure-sensitive adhesive layer and the adherend Bubbles are generated (foaming), and the optical film is lifted from the adherend or peeled off.
Therefore, by adjusting the molecular weight or the degree of crosslinking of the main polymer component of the pressure-sensitive adhesive used, the adhesive strength is increased to resist the dimensional change of the optical film and foam, float and peel even under harsh environments. Attempts have been made to prevent this from occurring.

  However, if an attempt is made to resist the dimensional change of the optical film simply by increasing the adhesive force, the stress distribution due to the dimensional change of the optical film that occurs under high temperature or high temperature and high humidity conditions becomes non-uniform, and the four corners of the optical film are not uniform. Concentrate on or at the edge of the periphery. As a result, when the optical film is a polarizing film used in a liquid crystal display device, there is a problem that a so-called “light leakage phenomenon” occurs in which light leaks from the four corners and peripheral edges of the liquid crystal display device.

  The following techniques have been proposed for the development of pressure-sensitive adhesives (pressure-sensitive adhesives) for adhering optical films, in which foaming does not occur at the interface with the adherend even under harsh conditions, and neither lifting nor peeling occurs.

  A high molecular weight (meth) acrylic copolymer, which is a copolymer of an alkyl (meth) acrylate and a polymerizable monomer having reactivity with a crosslinking agent and has a weight average molecular weight of 1,000,000 or more, and a weight average A pressure-sensitive adhesive for polarizing plates, comprising a low molecular weight (meth) acrylic copolymer having a molecular weight of 30,000 or less, and a polyfunctional compound having at least two functional groups capable of forming a crosslinked structure in the molecule, and the pressure-sensitive adhesive Has been proposed (Patent Document 1: Japanese Patent Laid-Open No. 10-279907).

  A pressure-sensitive adhesive layer containing a (meth) acrylic resin and a dye is provided on one surface of the light transmissive film, and the (meth) acrylic resin has a high molecular weight body having a weight average molecular weight of 200,000 or more and a weight average molecular weight. Has been proposed (Japanese Patent Application Laid-Open No. 2002-372619), which is composed of a low molecular weight material having a molecular weight of less than 200,000 and has a functional group.

  As the resin component, (A) a (meth) acrylic acid ester homopolymer or copolymer having a weight average molecular weight of 500,000 to 2,000,000, and (B) a (meth) acrylic acid ester having a weight average molecular weight of 5,000 to less than 500,000. A pressure-sensitive adhesive composition comprising a polymer or a copolymer and at least one of the component (A) and the component (B) is a (meth) acrylic acid ester copolymer having a nitrogen-containing functional group in the molecule The thing is proposed (patent document 3: Unexamined-Japanese-Patent No. 2001-89731).

  A copolymer having a weight average molecular weight of 1,000,000 to 2,000,000, which is obtained by radical copolymerization of a monomer having a reactive functional group and another monomer, and a monomer having a carboxyl group in the presence of this copolymer. A copolymer (B) having a weight average molecular weight of 10,000 or more and 100,000 or less obtained by radical copolymerization of a monomer and another monomer, and reacting with the copolymer (A) and / or the copolymer (B) A pressure-sensitive adhesive composed of a polyfunctional compound having at least two possible reactive functional groups, and an optical member in which a pressure-sensitive adhesive layer composed of this pressure-sensitive adhesive is formed on at least one surface of the optical member have been proposed ( Patent Document 4: JP 2004-331697 A).

  Furthermore, a pressure-sensitive adhesive composition comprising an alkyl (meth) acrylate copolymer, an antioxidant, and a curing agent, in which the gel fraction of the pressure-sensitive adhesive composition is adjusted, has been proposed (Patent Document 5: Japanese Patent Application Laid-Open No. H10-260260). 2003-49143).

These pressure-sensitive adhesives described in Patent Documents 1 to 5 have been improved so that they can withstand use under severe conditions, but after being attached to an adherend such as glass, they are heated at high temperature and pressure. Under pressure, when exposed to high temperature and high humidity, the adhesion between the pressure-sensitive adhesive and the glass that is the adherend has increased, so the pressure-sensitive adhesive remains on the glass that is the adherend. May end up.
In the past, there was no peeling after exposure to high temperature and high pressure, high temperature, and high temperature and high humidity, and there was no problem if rework was possible after checking for defects immediately after bonding. . However, recently, from the viewpoint of shortening the work process and recycling, the number of cases where the polarizing film is peeled off after being exposed to high temperature and high pressure, high temperature and high temperature and high humidity has increased the required rework characteristics. .

  Therefore, the present invention has good adhesion to the optical film, and even after the optical film is attached to the adherend, even if it is exposed to high temperature, high pressure, high temperature, high temperature and high humidity for a long period of time, foaming occurs at the adhesion interface. It does not occur, does not float or peel off, does not cause light leakage, and also has a pressure-sensitive adhesive capable of forming a pressure-sensitive adhesive layer that is excellent in reworkability, and a feeling using this pressure-sensitive adhesive It aims at providing a pressure type adhesive film.

According to one aspect of the present invention, a pressure-sensitive type containing a copolymer (C) having a hydroxyl group and / or a carboxyl group and having a glass transition temperature of −60 to 0 ° C. and an isocyanate curing agent (D). An adhesive,
The copolymer (C) is
(1) Alkyl methacrylate having no substituent (a): 15 to 35% by weight, alkyl acrylate having no substituent (b), and other ethylenic copolymerizable with the above (a) and (b) Radical copolymerization of a monomer (c) having a saturated double bond and comprising a monomer (c1) having a hydroxyl group and / or a carboxyl group and an ethylenically unsaturated double bond (Provided that the total of (a) to (c) is 100% by weight),
(2) including a high molecular weight component (A) and a low molecular weight component (B),
(2-1) A peak of a high molecular weight component (A1) having a weight average molecular weight of 500,000 to 2,200,000 completely independent on an emission curve in gel permeation chromatography and a low weight average molecular weight of 1,000 to 100,000 The area ratio between the peak of the high molecular weight component (A1) and the peak of the low molecular weight component (B1) is (A1) / (B1) = 60/40 to 90 / 10 or
(2-2) The peak of the high molecular weight component (A2) having a weight average molecular weight of 500,000 to 2,200,000 and the weight average molecular weight of 1,000 to 100,000 located on both sides of the minimum value of the discharge curve in gel permeation chromatography The area ratio of the peak of the high molecular weight component (A2) and the peak of the low molecular weight component (B2) is (A2) / (B2) = 60/40 to 90-3, or (2-3) In gel permeation chromatography, a peak of a high molecular weight component (A3) consisting of polymer molecules having a molecular weight of 150,000 or more and having a weight average molecular weight of 500,000 to 2,200,000 And a peak of a low molecular weight component (B3) consisting of polymer molecules having a molecular weight of less than 150,000 and having a weight average molecular weight of 1,000 to 100,000, and the high molecular weight component (A3) peak, The area ratio to the low molecular weight component (B3) peak is (A3) / (B3) = 60/40 to 90/10.
A pressure sensitive adhesive is provided.

According to another aspect of the present invention, a method for producing a pressure-sensitive adhesive comprising the following (I) to (III) is provided:
(I) Alkyl methacrylate having no substituent (a): 15 to 35% by weight, alkyl acrylate (b) having no substituent and other ethylenically unsaturated dialkylates copolymerizable with the above (a) and (b) A monomer (c) having a heavy bond and comprising a monomer (c1) having a hydroxyl group and / or a carboxyl group and an ethylenically unsaturated double bond is converted into a polymerization conversion ratio. Radical copolymerization to 60-90% to obtain a copolymer containing a high molecular weight component having a weight average molecular weight of 500,000-2,200,000;
(II) Next, the monomer (c) is added as necessary, and the above (a) to (c) are further radically copolymerized until the polymerization conversion rate becomes 80 to 100% (however, (a) to ( c) is 100% by weight),
(2-1) A peak of a high molecular weight component (A1) having a weight average molecular weight of 500,000 to 2,200,000 completely independent on an emission curve in gel permeation chromatography and a low weight average molecular weight of 1,000 to 100,000 The area ratio between the peak of the high molecular weight component (A1) and the peak of the low molecular weight component (B1) is (A1) / (B1) = 60/40 to 90 / 10 or
(2-2) The peak of the high molecular weight component (A2) having a weight average molecular weight of 500,000 to 2,200,000 and the weight average molecular weight of 1,000 to 100,000 located on both sides of the minimum value of the discharge curve in gel permeation chromatography The area ratio of the peak of the high molecular weight component (A2) and the peak of the low molecular weight component (B2) is (A2) / (B2) = 60/40 to 90-3, or (2-3) In gel permeation chromatography, a peak of a high molecular weight component (A3) consisting of polymer molecules having a molecular weight of 150,000 or more and having a weight average molecular weight of 500,000 to 2,200,000 And a peak of a low molecular weight component (B3) consisting of polymer molecules having a molecular weight of less than 150,000 and having a weight average molecular weight of 1,000 to 100,000, and the high molecular weight component (A3) peak, The area ratio to the low molecular weight component (B3) peak is (A3) / (B3) = 60/40 to 90/10.
A copolymer (C) comprising a high molecular weight component (A) and a low molecular weight component (B), having a hydroxyl group and / or a carboxyl group, and having a glass transition temperature of -60 to 0 ° C Obtaining (C); and (III) mixing the copolymer (C) and the isocyanate curing agent (D).

  According to still another aspect of the present invention, there is provided an optical film selected from the group consisting of a polarizing film and a retardation film, and a pressure-sensitive adhesive layer provided on at least one surface of the optical film, There is provided a pressure sensitive adhesive film comprising a pressure sensitive adhesive layer formed from a pressure sensitive adhesive according to one aspect of the invention.

The pressure-sensitive adhesive according to the present invention includes a copolymer (C), which is a main component of the pressure-sensitive adhesive, and an isocyanate curing agent (D), and forms a pressure-sensitive adhesive layer by reacting both. .
The copolymer (C) has a hydroxyl group and / or a carboxyl group, and its glass transition temperature (hereinafter also referred to as “Tg”) is −60 to 0 ° C. The copolymer (C) comprises an alkyl methacrylate (a) having no substituent, an alkyl acrylate (b) having no substituent, and other ethylenically unsaturated dimers copolymerizable with the above (a) and (b). The monomer (c) having a heavy bond is used as a constituent component. This monomer (c) contains at least a monomer (c1) having a hydroxyl group and / or a carboxyl group and an ethylenically unsaturated double bond.

This copolymer (C) contains a high molecular weight component (A) and a low molecular weight component (B).
There are the following three types of copolymers (C) depending on the form indicated by the discharge curve of gel permeation chromatography (hereinafter also referred to as “GPC”).
(2-1) A type in which the high molecular weight component (A1) and the low molecular weight component (B1) form a completely independent peak on GPC.
(2-2) A type showing a continuous peak in which a high molecular weight component (A2) and a low molecular weight component (B2) are connected by a minimum value (valley) on the GPC emission curve. The high molecular weight component (A2) is defined as the high molecular weight component and the low molecular component (B2) is defined as the low molecular component component. In many cases, the minimum value is between about 20,000 and 200,000 molecular weight.
(2-3) A type in which the high molecular weight component (A3) and the low molecular weight component (B3) show continuous peaks on the GPC emission curve and do not have a clear minimum value. In this case, with the molecular weight of 150,000 as the boundary, the high molecular weight side is the high molecular weight component (A3) and the low molecular weight side is the low molecular weight component (B3).

  The high molecular weight component (A) and the low molecular weight component (B) contained in the copolymer (C) are classified and specified as any one of the types (2-1) to (2-3), Any of (A1) and (B1), (A2) and (B2), (A3) and (B3). In any specific method, the high molecular weight component (A) has a weight average molecular weight of 500,000 to 2,200,000, and the low molecular weight component (B) has a weight average molecular weight of 1,000 to 100,000. The area ratio of the component (A) peak to the low molecular weight component (B) peak is (A) / (B) = 60/40 to 90/10.

  The alkyl methacrylate (a) having no substituent that constitutes the copolymer (C) is an alkyl methacrylate having no functional group such as a hydroxyl group or a carboxyl group (that is, the alkyl group in the ester portion has these functional groups). It is an alkyl group that does not have.) The alkyl group may be linear, may have a branched structure, or may have a cyclic structure. It is preferable that carbon number of this alkyl group is 1-6 from a reactive (polymerizable) viewpoint.

  Specifically, as the monomer (a), methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, n-pentyl methacrylate, 2-ethylhexyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, Examples thereof include n-heptyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, n-nonyl methacrylate, n-decyl methacrylate, undecyl methacrylate, dodecyl methacrylate and the like. These may be used alone or in appropriate combination of two or more.

  The alkyl acrylate (b) having no substituent means an alkyl acrylate having no functional group such as a hydroxyl group or a carboxyl group (that is, an alkyl group in the ester part is an alkyl group having no such functional group). It is. The alkyl group may be linear, may have a branched structure, or may have a cyclic structure. The number of carbon atoms of the alkyl group is preferably 2 to 6 because it becomes difficult to foam in the durability test after sticking.

  Specifically, as monomer (b), methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, cyclohexyl acrylate, n-pentyl acrylate, 2-ethylhexyl acrylate, n-hexyl acrylate, Examples thereof include n-heptyl acrylate, n-octyl acrylate, isooctyl acrylate, n-nonyl acrylate, decyl acrylate, undecyl acrylate, and dodecyl acrylate. These may be used alone or in appropriate combination of two or more.

Examples of the other monomer (c) having an ethylenically unsaturated double bond copolymerizable with the above (a) and (b) include the following (c1) to (c3).
(C1): A monomer having a hydroxyl group and / or a carboxyl group and having an ethylenically unsaturated double bond. It is used for introducing a hydroxyl group and / or a carboxyl group into the copolymer (C).
(C2): A monomer having a substituent other than a hydroxyl group or a carboxyl group and an ethylenically unsaturated double bond.
(C3): Other monomer having an ethylenically unsaturated double bond that is not classified as any of the above monomers.
Monomers (c2) and (c3) are optional components.

As the monomer (c1) having a hydroxyl group and an ethylenically unsaturated double bond, (meth) acrylates having a hydroxyl group in the ester moiety, such as a (meth) acrylic ester of a polyol, are preferred. Specifically, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, Glycerol mono (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, caprolactone-modified (meth) acrylates Polyethylene glycol (meth) acrylates, polypropylene glycol (meth) acrylates and the like.
Here, “2-hydroxyethyl (meth) acrylate” is an abbreviation of “2-hydroxyethyl acrylate” and “2-hydroxyethyl methacrylate”. Others are the same.

  As the monomer (c1) having a carboxyl group and an ethylenically unsaturated double bond, acrylic acid, methacrylic acid, β-carboxyethyl acrylate, itaconic acid, maleic acid, maleic anhydride, crotonic acid, fumaric acid, anhydrous Examples include fumaric acid.

Any one of these exemplified monomers (c1) may be used, or plural types may be used in any combination.
Examples of other substituents and monomers (c2) having an ethylenically unsaturated double bond that can be used in combination with the monomer (c1) include amino groups, amide groups, maleimide groups, itaconimide groups, and nucleenimides. And a monomer having at least one substituent selected from the group consisting of a group and an epoxy group and an ethylenically unsaturated double bond. A plurality of types of monomers (c2) can also be used in combination.

  As the monomer (c2) having an amino group and an ethylenically unsaturated double bond, aminomethyl (meth) acrylate, dimethylaminomethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) An acrylate etc. are mentioned.

  Examples of the monomer (c2) having an amide group and an ethylenically unsaturated double bond include (meth) acrylamide, N-substituted (meth) acrylamide, N-vinylpyrrolidone and the like.

  Examples of the monomer (c2) having a maleimide group and an ethylenically unsaturated double bond include N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide and the like.

  As the monomer (c2) having an itacimide group and an ethylenically unsaturated double bond, N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexyl Itaconimide, N-cyclohexyl leuconconimide, N-lauryl itaconimide and the like can be mentioned.

  As the monomer (c2) having a nucleenimide group and an ethylenically unsaturated double bond, N- (meth) acryloyloxymethylene nucleenimide, N- (meth) acryloyl-6-oxyhexamethylene nucleenimide, N -(Meth) acryloyl-8-oxyoctamethylene nucleimide is exemplified.

  Examples of the monomer (c2) having an epoxy group and an ethylenically unsaturated double bond include glycidyl (meth) acrylate.

Other monomers (c3) having an ethylenically unsaturated double bond, which are not classified as any of the above monomers,
Vinyl monomers such as styrene, methylstyrene, vinyltoluene, vinyl acetate;
Divinyl monomers such as divinylbenzene;
1,4-butyl diacrylate, 1,6-hexyl diacrylate, hexanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di And diacrylate monomers such as (meth) acrylate and pentaerythritol di (meth) acrylate; and phosphate group-containing monomers such as 2-hydroxyethylacryloyl phosphate.

  Of these, the use of a polyfunctional monomer such as a divinyl monomer or a diacrylate monomer is preferable because the durability (heat resistance and heat and humidity resistance) of the formed pressure-sensitive adhesive layer is improved. However, if a polyfunctional monomer is used in obtaining the copolymer (C), gelation tends to occur, and therefore it is preferable to use a small amount. Specifically, when the total amount of the monomers (a), (b), and (c) used for forming the copolymer (C) is 100% by weight, the blending amount of the polyfunctional monomer is 0.001. It is preferable to be in the range of ˜3% by weight.

When the total amount of the monomers (a), (b) and (c) used for the formation of the copolymer (C) is 100% by weight, it is exposed to high temperature and high pressure, high temperature and high temperature and high humidity as described later. From the viewpoint of obtaining appropriate reworkability after the treatment, it is important that the amount of the alkyl methacrylate (a) having no substituent is 15 to 35% by weight.
Furthermore, it is important that Tg of the copolymer (C) is −60 to 0 ° C., and preferably −55 to −5 ° C. When this Tg is lower than −60 ° C., the pressure-sensitive adhesive layer is liable to float, peel off, foam and the like at high temperature and high temperature and high humidity.

  In general, the main component for forming the pressure-sensitive adhesive layer needs to be in a region where Tg is 0 ° C. or lower. In the case of a general acrylic pressure-sensitive adhesive, in order to lower the Tg of the acrylic copolymer as the main component, alkyl acrylate (b) having no substituent is mainly used as a monomer constituting the acrylic copolymer. Need to be an ingredient. On the other hand, the alkyl methacrylate (a) having no substituent, which is a component that raises Tg, is not used at all or even if used, only a very small amount is used to control Tg.

Also in the present invention, in order for the Tg of the copolymer (C) to be −60 to 0 ° C., the monomer used for forming the copolymer (C) is quantitatively substituted. Alkyl acrylate (b) having no group needs to be the main component.
However, according to the knowledge of the present inventors, if the amount of the alkyl acrylate (b) having no substituent is too much, the flexibility of the main chain of the formed copolymer becomes too high. As a result, the pressure-sensitive adhesive layer formed by the reaction of such a copolymer and the curing agent (D) described later is excessively softened at high temperature or high temperature and high humidity, so that it is pressure sensitive to the adherend. It has been found that when the adhesive film is applied and exposed to a high temperature or high temperature and high humidity for a long period of time, the film is liable to float, peel off or foam.

Accordingly, in the case of a general acrylic pressure-sensitive adhesive, it is not used at all, or even if it is used, only a small amount is used for controlling Tg. Alkyl methacrylate having no substituent (a) Is 15 to 35% by weight, and it is characteristic in the present invention to be used in a large amount as compared with conventional acrylic pressure-sensitive adhesives, and is extremely important.
That is, the presence of the methyl group of the alkyl methacrylate (a) having no substituent increases the steric hindrance of the main chain of the formed copolymer (C), thereby suppressing the translation, vibration, and rotational movement of the main chain. The As a result, it is considered that even if a pressure-sensitive adhesive film is attached to an adherend and exposed to a high temperature or high temperature and high humidity for a long period of time, there is no effect of floating, peeling, foaming or the like.

When the alkyl methacrylate (a) having no substituent is less than 15 parts by weight, the translation, vibration, and rotation of the main chain become too large, so that it cannot withstand the harsh environment as described above, and floats and peels off. , Foaming and the like are likely to occur.
On the other hand, when the alkyl methacrylate (a) having no substituent exceeds 35% by weight, the translation, vibration, and rotational motion of the main chain are excessively suppressed, so that the pressure-sensitive adhesive layer becomes rigid. In this case, when the dimension of the optical film as the base material changes due to the harsh environment as described above, the rigid pressure-sensitive adhesive layer resists the dimensional change too much, and the resistance force becomes the peripheral edge of the optical film as the base material. As a result, the light leakage phenomenon at the peripheral edge portion occurs.

  The copolymer (C) needs to have a hydroxyl group and / or a carboxyl group as a functional group for reacting with the isocyanate curing agent (D) described later. The amount of the monomer (c1) having a hydroxyl group and / or a carboxyl group and an ethylenically unsaturated double bond used for introducing a hydroxyl group or a carboxyl group is a single amount constituting the copolymer (C). It is preferably 0.01 to 10% by weight and more preferably 0.05 to 8% by weight in the total 100% by weight of the body. When the monomer (c1) is less than 0.01% by weight, the cohesive force as a pressure-sensitive adhesive layer is insufficient, and the pressure-sensitive adhesive film is floated / peeled, foamed, etc. at high temperature or high temperature / high humidity. It tends to occur. On the other hand, if the monomer (c1) exceeds 10% by weight, the degree of crosslinking becomes too high and the pressure-sensitive adhesiveness (tackiness) becomes poor, which is not preferable.

As described above, the amount of alkyl methacrylate (a) having no substituent, the amount of monomer (c1) having a hydroxyl group and / or carboxyl group and an ethylenically unsaturated double bond, and the copolymer (C ) In consideration of the Tg of the copolymer (C), the amount of monomers other than (a) and (c1), that is, alkyl acrylate (b) having no substituent, hydroxyl group or carboxyl A monomer (c2) having a substituent other than a group and an ethylenically unsaturated double bond, and other monomers having an ethylenically unsaturated double bond not classified as any of the above monomers (c3) ) Can be appropriately selected.
For example, the alkyl acrylate (b) having no substituent is preferably 45% by weight or more, and more preferably 50 to 78% by weight.

The copolymer (C) contains two copolymer components, a high molecular weight component (A) and a low molecular weight component (B) as described above. These two copolymer components are classified into the following three types according to the peak shape of the GPC discharge curve.
That is, (2-1) When the copolymer (C) has a completely independent peak on the GPC discharge curve, the copolymer (C) has a high molecular weight component (A1) on the high molecular weight side. And (A1) and (B1) are contained with the low molecular weight side as the low molecular weight component (B1).
(2-2) The copolymer (C) has a continuous peak on the GPC discharge curve, and has a minimum value (valley), specifically a minimum value between about 20,000 and 200,000 in molecular weight. In the case of having the copolymer (C), the high molecular weight side is defined as the high molecular weight component (A2) and the low molecular weight side is defined as the low molecular weight component (B2) with the minimum value as a boundary, and (A2) and (B2) Containing.
(2-3) When the copolymer (C) does not have a clear minimum value between about 20,000 and 200,000 in the GPC emission curve, the copolymer (C) has a molecular weight of 150,000. As a boundary, a copolymer composed of polymer molecules having a molecular weight of 150,000 or more is defined as a high molecular weight component (A3), and a copolymer component composed of polymer molecules having a molecular weight of less than 150,000 is defined as a low molecular weight component (B3). ) And (B3).

The weight average molecular weights of the high molecular weight components (A1), (A2), and (A3) specified as described above are 500,000 to 2,200,000, and preferably 700,000 to 2,000,000. The weight average molecular weights of the low molecular weight components (B1), (B2), and (B3) specified as described above are 1,000 to 100,000, and preferably 5,000 to 80,000.
If the weight average molecular weight of the high molecular weight component (A) is less than 500,000, the cohesive force of the pressure-sensitive adhesive layer will be insufficient even when reacted with the isocyanate-based curing agent (D) described later, causing floating / peeling, foaming, etc. Arise. On the other hand, if the weight average molecular weight of the high molecular weight component (A) is greater than 2,200,000, the viscosity becomes high and the workability such as coating becomes inferior, and the optical properties cannot be maintained.
On the other hand, when the low molecular weight component (B) having a weight average molecular weight of less than 1000 is used, the cohesive force is insufficient, and it tends to float, peel off and foam. Moreover, when the low molecular weight component (B) having a weight average molecular weight exceeding 100,000 is used, the stress concentration resulting from the expansion and contraction of the film cannot be sufficiently absorbed and relaxed, and a light leakage phenomenon occurs.

Furthermore, the area ratio of peaks in GPC of the high molecular weight components (A1), (A2), (A3) and the low molecular weight components (B1), (B2), (B3) is (A1) / (B1) = 60. / 40 to 90/10, or (A2) / (B2) = 60/40 to 90/10, or (A3) / (B3) = 60/40 to 90/10. It is important that each is preferably 65/35 to 85/15.
If the proportion of the low molecular weight component (B) is too small, the stress concentration resulting from the expansion and contraction of the optical film cannot be sufficiently absorbed and relaxed, and a light leakage phenomenon occurs. On the other hand, when the proportion of the low molecular weight component (B) is too large, the cohesive force of the pressure-sensitive adhesive layer is insufficient, and it tends to float, peel off, foam and the like.
Furthermore, since the high molecular weight component (A) and the low molecular weight component (B) are contained at a ratio of 60/40 to 90/10, the adhesive layer has good reworkability even after being placed under severe conditions. Can be obtained.

Such a copolymer (C) can be obtained by various methods. For example, the high molecular weight component (A) and the low molecular weight component (B) can be obtained separately and mixed to obtain the high molecular weight component (that is, the above (A1) to (A3)). In the presence of the obtained copolymer to obtain a low molecular weight component, and a copolymer containing both is obtained. A polymer (C) can also be obtained.
From the viewpoint of maintaining optical properties at high temperature or high temperature and high humidity, the latter method is more preferable.

In the following, after obtaining a high molecular weight component (first stage polymerization), which is a more preferable method, a monomer is polymerized (second stage polymerization) in the presence of the obtained high molecular weight component to obtain a low molecular weight component. The method for obtaining the components will be described in more detail.
For example, the high molecular weight component is 0.01 to 1 part by weight of the polymerization initiator, more preferably, 0.1 parts by weight with respect to a total of 100 parts by weight of the monomers (a) to (c) used in the first stage. It is obtained by a method such as bulk polymerization or solution polymerization, preferably solution polymerization, using a polymerization initiator of 01 to 0.1.

As the polymerization initiator, an azo compound or an organic peroxide is used, and two or more polymerization initiators may be used in combination.
In the case of solution polymerization, as a polymerization solvent, methyl acetate, ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, xylene, hexane, acetone, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, n-propanol, isopropanol, etc. are used. It is done. Two or more kinds of polymerization solvents may be mixed and used.

  Among the polymerization initiators, examples of the azo compound include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane 1- Carbonitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2′-azobis (2- Methyl propionate), 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2-hydroxymethylpropionitrile), 2,2′-azobis (2- (2-imidazoline) -2-yl) propane) and the like.

  Examples of the organic peroxide include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, and di (2-ethoxyethyl) peroxy. Examples include dicarbonate, t-butyl peroxyneodecanoate, t-butyl peroxybivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide and the like.

First, it is preferable to polymerize the monomers (a) to (c) until the polymerization conversion becomes 60 to 90% by controlling the blending amount of the polymerization initiator as described above. A copolymer constituting the high molecular weight component (A) of the copolymer (C) can be obtained in the system by the step polymerization. The copolymer obtained by the first stage polymerization mainly comprises the high molecular weight component (A), but may contain other copolymerization components.
Here, the polymerization conversion rate is a value obtained by dividing the weight of the copolymer obtained by polymerizing the monomer by the total weight of the monomers used as raw materials. More specifically, a very small amount of the solution during polymerization is sampled and heated at 150 ° C. for about 20 minutes to obtain the solid content. The monomer volatilizes under the heating conditions, but the copolymer does not volatilize. Therefore, by obtaining the solid content of the solution, the amount of the copolymer contained can be obtained, and the polymerization conversion rate is calculated based on that.

Then, if necessary, new monomers (a) to (c) and / or a polymerization initiator are added, and as a second stage polymerization, monomers remaining in the system after the first stage polymerization (and A new monomer added as necessary) is further radically polymerized to form the low molecular weight component (B). Thereby, the copolymer (C) containing a high molecular weight component (A) and a low molecular weight component (B) can be obtained.
The polymerization conversion rate of the copolymer (C) in the second stage polymerization is preferably 80 to 100%, more preferably 90 to 100%, and further preferably 95 to 100%. That is, the monomer remaining in the reaction system is preferably 20% of the total 100% by weight of the monomers used in the polymerization, including the monomer added as necessary in the second stage polymerization step. To obtain a copolymer (C) by radical copolymerization to form a low molecular weight component until it is less than 10%, more preferably less than 10% by weight, and even more preferably less than 5% by weight. Can do.

  In this second stage polymerization, it is preferable to add a new monomer (c), and in particular, a monomer (c1) having a hydroxyl group and / or a carboxyl group and an ethylenically unsaturated double bond is added. More preferably. The monomer (c1) is 0.01 to 10% by weight in 100% by weight in total of all monomers used for the polymerization of the high molecular weight component (A) and the low molecular weight component (B) as described above. It is preferable that it is 0.05 to 8% by weight. Among these, the amount of the monomer (c1) used in the first stage polymerization is preferably 0.008 to 8% by weight, and more preferably 0.04 to 6% by weight. The amount of the monomer (c2) newly added during the second stage polymerization is preferably 0.002 to 2% by weight, more preferably 0.01 to 2% by weight. . A monomer (c1) is added, and by introducing a hydroxyl group and / or a carboxyl group into the low molecular weight component (B), the pressure sensitive adhesive from the end when the optical film is cut is added. It is effective in preventing protrusion.

When the low molecular weight component (B) is formed in the second stage polymerization, the polymerization initiator used in the first stage is more than the polymerization initiator used in the first stage. It is preferable to use about 50 times the weight of the polymerization initiator. More specifically, 0.05 to 50 parts by weight of a polymerization initiator, more preferably 0.05 to 100 parts by weight of the total of the monomers (a) to (c) used in the second stage. It is preferred to use -5 parts by weight of a polymerization initiator.
Furthermore, in order to control the molecular weight to the low molecular weight side, during the synthesis of the low molecular weight component (B), mercaptans such as n-lauryl mercaptan and n-dodecyl mercaptan, chain transfer agents such as α-methylstyrene dimer and limonene are used. May be used.
Thus, in GPC, the copolymer (C) in which the area ratio of the high molecular weight component (A) to the low molecular weight component (B) is (A) / (B) = 60/40 to 90/10 is preferable. Can be obtained.

A pressure-sensitive adhesive can be obtained by mixing the copolymer (C) having a hydroxyl group and / or a carboxyl group obtained as described above and an isocyanate curing agent (D). When obtaining the pressure-sensitive adhesive film, the isocyanate curing agent (D) reacts with the hydroxyl group and / or carboxyl group of the copolymer (C) to form a pressure-sensitive adhesive layer.
Upon mixing, the copolymer (C) is preferably in a solution state dissolved in an organic solvent.

As an isocyanate type hardening | curing agent (D), what has 2 or more of isocyanate groups in 1 molecule is preferable, and what has 2-4 pieces is more preferable.
By using the isocyanate-based curing agent (D), a stable pressure-sensitive adhesive property can be obtained, and the adhesiveness to the base material is lost, so that it is a useful curing agent.

As an example of the isocyanate curing agent (D),
Tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethylxylylene diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, polymethylene polyphenyl isocyanate, etc. A polyisocyanate compound;
Adducts of these polyisocyanate compounds and polyol compounds such as trimethylolpropane;
Examples include burettes or isocyanurates of these polyisocyanate compounds; and adducts of these polyisocyanate compounds with known polyether polyols or polyester polyols, acrylic polyols, polybutadiene polyols, polyisoprene polyols, and the like. These may be used alone or in any combination of two or more.
The isocyanate curing agent (D) is preferably used in an amount of 0.01 to 15 parts by weight with respect to 100 parts by weight of the copolymer (C). If it is less than 0.01 part by weight, the cohesive force of the pressure-sensitive adhesive layer tends to decrease, and if it exceeds 15 parts by weight, the pressure-sensitive adhesiveness to the adherend becomes poor. More preferably, it is 0.03-10 weight part, and 0.05-2 weight part is especially preferable.

  In the pressure-sensitive adhesive, a curing agent other than the isocyanate curing agent (D), for example, one or more of an epoxy curing agent, an ethyleneimine curing agent, a metal chelate curing agent, and an amine curing agent is used. It can be used in combination with the agent (D). It is preferable that the compounding quantity in the case of mix | blending hardeners other than these isocyanate type hardening | curing agents (D) is 0.01-8 weight part with respect to 100 weight part of copolymers (C).

  Examples of epoxy curing agents include bisphenol A-epichlorohydrin type epoxy resins, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol. Diglycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl aniline, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine, 1,3-bis (N, N′-diglycidylaminomethyl) Examples include cyclohexane, N, N, N ′, N′-tetraglycidylaminophenylmethane, and the like.

  Examples of the ethyleneimine curing agent include N, N′-diphenylmethane-4,4′-bis (1-aziridinecarboxite), N, N′-toluene-2,4-bis (1-aziridinecarboxite). Bisisophthaloyl-1- (2-methylaziridine), tri-1-aziridinylphosphine oxide, N, N′-hexamethylene-1,6-bis (1-aziridinecarboxite), 2,2 ′ -Bishydroxymethylbutanol-tris [3- (1-aziridinyl) propionate], trimethylolpropane tri-β-aziridinylpropionate, tetramethylolmethanetri-β-aziridinylpropionate, Tris-2, 4,6- (1-aziridinyl) -1,3,5-triazine and the like can be mentioned.

  Examples of metal chelate curing agents include coordination compounds of polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium and zirconium with acetylacetone or ethyl acetoacetate Is mentioned.

  Furthermore, examples of the amine curing agent include hexamethylenediamine, triethyldiamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethyltetramine, isophoronediamine, amino resin, and methylene resin.

It is preferable to add a silane coupling agent to the pressure-sensitive adhesive.
As silane coupling agents, vinyltrimethoxysilane, vinyltriethoxysilane, methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyl Dimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyl Methoxysilane, N- (2-aminoethyl) 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mer Hept triethoxysilane, mercaptopropyl butyl trimethoxysilane, .gamma.-mercaptopropyl methyl dimethoxy silane, and the like. You may use these in combination of 2 or more type.
The silane coupling agent is effective in improving the adhesion between the pressure-sensitive adhesive layer and the glass, and is particularly effective in preventing the pressure-sensitive adhesive film from floating / peeling and foaming under high temperature and high humidity.

  The content of the silane coupling agent in the pressure-sensitive adhesive is preferably 0.01 to 2 parts by weight with respect to 100 parts by weight of the copolymer (C). If the amount is less than 0.01 parts by weight, the effect of improving the physical properties is poor. If the amount exceeds 2 parts by weight, the pressure-sensitive adhesive is not only expensive, but may cause floating, peeling, foaming, and the like. .

  Furthermore, the pressure-sensitive adhesive is one of known additives such as an ultraviolet absorber, an antioxidant, a pressure-sensitive adhesion-imparting resin, a plasticizer, an antifoaming agent, and a leveling regulator as long as the effects of the present invention are not impaired. You may mix | blend a seed | species or more arbitrarily.

  By using the pressure-sensitive adhesive according to the present invention, the adhesiveness to the optical film is good, and after the optical film is attached to the adherend, it is exposed for a long time under high temperature and high pressure, high temperature or high temperature and high humidity. However, it is possible to form a pressure-sensitive adhesive layer that not only causes foaming at the sticking interface, does not float and peel, does not cause light leakage, and also has excellent reworkability.

Next, a pressure sensitive adhesive film obtained using the pressure sensitive adhesive will be described.
In this pressure-sensitive adhesive film, a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive is formed on at least one surface of an optical film used for various display members.
The pressure-sensitive adhesive film is suitably used for forming various display members. For example, the pressure-sensitive adhesive film is suitably attached to a glass of a liquid crystal display member.
Examples of the optical film include a polarizing film and a retardation film, and a polarizing film is preferable.

The pressure-sensitive adhesive film can be formed by applying a pressure-sensitive adhesive to the surface of the optical film and drying to form a pressure-sensitive adhesive layer. Preferably, a release sheet is laminated on the obtained pressure-sensitive adhesive layer. If necessary, the adhesive layer may be aged.
Alternatively, the pressure-sensitive adhesive layer on the optical film can be formed by applying a pressure-sensitive adhesive to the release sheet, drying to form a pressure-sensitive adhesive layer, and then bonding it to the optical film. The pressure-sensitive adhesive layer can be transferred onto an optical film by a so-called “transfer method”.

The pressure-sensitive adhesive layer can be formed using a commonly used coating apparatus. Examples of the coating apparatus include a roll knife coater, a die coater, a roll coater, a bar coater, a gravure roll coater, a reverse roll coater, dipping, and a blade coater.
The thickness (after drying) of the pressure-sensitive adhesive layer is preferably 1 to 200 μm. If it is less than 1 μm, the pressure-sensitive adhesiveness may be poor, and if it exceeds 200 μm, the production and handling of the pressure-sensitive adhesive film may be difficult.

Pressure-sensitive adhesive layer obtained in the manner described above, the storage elastic modulus at 25 ° C., is preferably ^{0.01 × 10 5 Pa~5 × 10 5} Pa. More preferably ^{0.05 × 10 5 ~3 × 10 5} . The storage elastic modulus can be measured using a viscoelasticity tester “RDA-III” manufactured by TA Instruments Japan.

When the storage elastic modulus at 25 ° C. of the pressure-sensitive adhesive layer is smaller than 0.01 × 10 ⁵ Pa, after bonding to an adherend such as glass, it is exposed to a high temperature or high temperature and high humidity for a long time, There is a possibility that the pressure-sensitive adhesive layer is softened and is liable to float, peel off, foam or the like. On the other hand, when the storage elastic modulus at 25 ° C. of the pressure-sensitive adhesive layer is larger than 5 × 10 ⁵ Pa, the heat resistance is sufficiently high, but the pressure-sensitive adhesive layer is hard at room temperature, so the pressure-sensitive adhesive layer is attached to the adherend. When bonding the adhesive film, the pressure-sensitive adhesive layer does not fully adapt to the adherend, and the pressure-sensitive adhesive force tends to decrease.

EXAMPLES Next, although an Example of this invention is shown and it demonstrates still in detail, this invention is not limited by these. In the examples, “part” means “part by weight”, and “%” means “% by weight”.
In the following production examples and comparative production examples, for convenience, a copolymer component having a weight average molecular weight of 100,000 or more is designated as “high molecular weight component (A)”, and a copolymer component having a weight average molecular weight of less than 100,000 is designated as “low and high”. The molecular weight component (B) ”was assigned a serial number. Further, the copolymer was given a serial number as “C” regardless of whether or not it was an embodiment of the present invention.

<Production Example 1>
In a reaction vessel (hereinafter simply referred to as “reaction vessel”) equipped with a stirrer, thermometer, reflux condenser, dropping device, and nitrogen introduction tube, 76 parts of n-butyl acrylate, 22 parts of methyl methacrylate, 1 acrylic acid 0.5 part, 100 parts of acetone, and 0.03 part of AIBN (2,2′-azobisisobutyronitrile, hereinafter referred to as “AIBN”) were charged, and the air in the reaction vessel was replaced with nitrogen gas. . Thereafter, while stirring under a nitrogen atmosphere, this reaction solution is reacted at a reflux temperature for 4.5 hours until the conversion becomes 75%, and a mixed solution of a copolymer having a weight average molecular weight of 1,000,000 and a monomer. Got. Next, 200 parts of toluene, 0.5 part of acrylic acid, and 0.2 part of AIBN were added, and the reaction was further continued for 6 hours until the conversion reached 100%, and the copolymer (C1) having a Tg of −29.4 ° C. A solution was obtained.

  The copolymer (C1) does not contain a polymer having a molecular weight of less than 150,000, has a weight average molecular weight of 1,000,000, a high molecular weight component (A1-1) having a Tg of −29.9 ° C., and a weight of 150,000 or more. It contained no coalesce and contained a low molecular weight component (B1-1) having a weight average molecular weight of 30,000 and a Tg of −28 ° C. The high molecular weight component (A1-1) and the low molecular weight component (B1-1) show two independent peaks in the GPC discharge curve, and the area ratio between them is (A1-1) / (B1-1 ) = 75/25.

The Tg of the high molecular weight component (A1-1) is expressed by the following formula based on the glass transition temperature of the homopolymer obtained from each monomer, assuming that each monomer used is uniformly polymerized. This is the value obtained by (1). The Tg of the low molecular weight component (B1-1) is based on the unreacted remaining monomer and the amount of each added monomer and the glass transition temperature of the homopolymer obtained from each monomer. It is the value calculated | required by the following formula | equation (1). The Tg of the copolymer (C1) is expressed by the following formula (based on the glass transition temperature of the homopolymer obtained from each monomer (that is, the blended monomer) constituting the copolymer (C1): This is the value obtained by 1).
Formula (1) (Form of FOX):
1 / Tg = [(W1 / Tg1) + (W2 / Tg2) + ... + (Wn / Tgn)]
/ 100 (Here, the temperature is an absolute temperature.)
Wn:% by weight of monomer n
Tgn: Glass transition temperature of homopolymer composed of monomer n

<Production Example 2>
In a reaction vessel, 73.98 parts of n-butyl acrylate, 24 parts of n-butyl methacrylate, 1.5 parts of acrylic acid, light acrylate 4EG-A (PEG # 200 diacrylate, manufactured by Kyoeisha Chemical Co., Ltd., the same shall apply hereinafter) 02 parts, 100 parts of acetone and 0.03 part of AIBN were charged and reacted for 4.5 hours until the conversion rate reached 75% in the same manner as in Production Example 1, and the copolymer and the monomer having a weight average molecular weight of 980,000 were used. A mixed solution with the body was obtained.
Next, 200 parts of toluene, 0.5 part of acrylic acid, and 0.2 part of AIBN were added, and the reaction was further continued for 6 hours until the conversion reached 100%, and the copolymer (C2) having a Tg of −37.8 ° C. A solution was obtained.

The copolymer (C2) does not contain a polymer having a molecular weight of less than 150,000, has a weight average molecular weight of 980,000, a high molecular weight component (A1-2) having a Tg of −38.2 ° C., and a heavy weight having a molecular weight of 150,000 or more. A low molecular weight component (B1-2) having a weight average molecular weight of 31,000 and a Tg of −36.4 ° C. was contained. The high molecular weight component (A1-2) and the low molecular weight component (B1-2) show two independent peaks in the GPC emission curve, and the area ratio between them is (A1-2) / (B1-2). ) = 75/25.
In addition, Tg was calculated | required except the light acrylate 4EG-A which was trace amount.

<Production Example 3>
A reaction vessel was charged with 74 parts of n-butyl acrylate, 24 parts of methyl methacrylate, 1.5 parts of acrylic acid, 100 parts of acetone and 0.03 part of AIBN, and the same procedure as in Production Example 1 was carried out until the conversion reached 65%. The mixture was reacted for a time to obtain a mixed solution of a copolymer having a weight average molecular weight of 1,10,000 and a monomer.
Subsequently, 200 parts of toluene, 0.5 part of 2-hydroxyethyl methacrylate, and 0.2 part of AIBN were added, and the mixture was further reacted for 6 hours until the conversion reached 100%. A copolymer having a Tg of −27.1 ° C. ( A solution of C3) was obtained.

  The copolymer (C3) does not contain a polymer having a molecular weight of less than 150,000, has a weight average molecular weight of 1.10,000, a Tg of −27.6 ° C., a high molecular weight component (A1-3), and a molecular weight of 150,000 or more. A low molecular weight component (B1-3) having a weight average molecular weight of 28,000 and a Tg of −26.3 ° C. was contained. The high molecular weight component (A1-3) and the low molecular weight component (B1-3) show two independent peaks in the GPC discharge curve, and the area ratio between them is (A1-3) / (B1-3). ) = 65/35.

<Production Example 4>
A reaction vessel was charged with 83 parts of n-butyl acrylate, 15 parts of methyl methacrylate, 1.5 parts of acrylic acid, 100 parts of acetone and 0.03 part of AIBN, and the same procedure as in Production Example 1 was carried out until the conversion rate reached 85%. The mixture was reacted for a time to obtain a mixed solution of a copolymer having a weight average molecular weight of 1,000,000 and a monomer.
Next, 200 parts of toluene, 0.5 part of acrylic acid, and 0.2 part of AIBN were added, and the reaction was further continued for 6 hours until the conversion reached 100%, and the copolymer (C4) having a Tg of −37.1 ° C. A solution was obtained.

  The copolymer (C4) does not contain a polymer having a molecular weight of less than 150,000, has a weight average molecular weight of 1,000,000, a high molecular weight component (A1-4) having a Tg of -37.6 ° C., and a weight of 150,000 or more. A low molecular weight component (B1-4) having a weight average molecular weight of 37,000 and a Tg of −35.8 ° C. was contained. The high molecular weight component (A1-4) and the low molecular weight component (B1-4) show two independent peaks in the GPC discharge curve, and the area ratio between them is (A1-4) / (B1-4). ) = 85/15.

<Production Example 5>
The same as in Production Example 2, except that the monomer composition was 82.98 parts of n-butyl acrylate, 15 parts of methyl methacrylate, 1.5 parts of 2-hydroxyethyl methacrylate, and 0.02 parts of light acrylate 4EG-A. The mixture was reacted until the conversion rate reached 75% to obtain a mixed solution of a copolymer having a weight average molecular weight of 1,000,000 and a monomer.
Next, the reaction was continued until the conversion reached 100%, except that 0.5 part of 2-hydroxyethyl methacrylate was added instead of 0.5 part of acrylic acid, and the Tg was -37 ° C. A solution of the polymer (C5) was obtained.

The copolymer (C5) does not contain a polymer having a molecular weight of less than 150,000, has a weight average molecular weight of 1 million, a high molecular weight component (A1-5) having a Tg of −37.9 ° C., and a weight of 150,000 or more. It contained no coalesce, and contained a low molecular weight component (B1-5) having a weight average molecular weight of 31,000 and Tg of −35.6 ° C. The high molecular weight component (A1-5) and the low molecular weight component (B1-5) show two independent peaks in the GPC discharge curve, and the area ratio between them is (A1-5) / (B1-5). ) = 75/25.
In addition, Tg was calculated | required except the light acrylate 4EG-A which was trace amount.

<Production Example 6>
A reaction vessel was charged with 78 parts of n-butyl acrylate, 20 parts of methyl methacrylate, 2 parts of acrylic acid, 100 parts of acetone, and 0.03 part of AIBN, and the air in the reaction container was replaced with nitrogen gas. Thereafter, while stirring in a nitrogen atmosphere, this reaction solution is reacted for 6 hours at a reflux temperature until the conversion becomes 100%, and does not contain a component having a weight average molecular weight of 1050,000 and a molecular weight of less than 150,000, and Tg is − A solution of the high molecular weight copolymer (A1-6) at 31.7 ° C. was obtained. The obtained copolymer solution was diluted with toluene, and the non-volatile content concentration was adjusted to 40%.

  In a separate reaction vessel, 78 parts of n-butyl acrylate, 20 parts of methyl methacrylate, 2 parts of acrylic acid, 150 parts of toluene and 0.03 part of AIBN were charged, and the air in the reaction container was replaced with nitrogen gas. Thereafter, while stirring in a nitrogen atmosphere, this reaction solution is reacted for 6 hours at a reflux temperature until the conversion becomes 100%. The Tg is −31.7 ° C., the weight average molecular weight is 30,000, and the molecular weight is 150,000 or more. A solution of a low molecular weight copolymer (B1-6) containing no components was obtained (nonvolatile content concentration: 40%).

  Next, both copolymer solutions were prepared so that the weight ratio of the high molecular weight component (A1-6) to the low molecular weight component (B1-6) was (A1-6) / (B1-6) = 75/25. After mixing, a copolymer (C6) solution having a Tg of −31.7 ° C. was obtained, and GPC was measured. The area ratio of the high molecular weight component (A1-6) to the low molecular weight component (B1-6) was (A1-6) / (B1-6) = 75/25.

<Production Example 7>
In a reaction vessel, 67.98 parts of n-butyl acrylate, 30 parts of methyl methacrylate, 2 parts of 2-hydroxyethyl methacrylate, 0.02 part of light acrylate 4EG-A, 110 parts of acetone and 0.03 part of AIBN were prepared, and Production Example 6 In the same manner as described above, the reaction is allowed to proceed for 6 hours until the conversion becomes 100%, and no high molecular weight copolymer having a weight average molecular weight of 1050,000 and a molecular weight of less than 150,000, Tg of −19.9 ° C. (A1 A solution of -7) was obtained. The obtained copolymer solution was diluted with toluene, and the non-volatile content concentration was adjusted to 40%.

  In a separate reaction vessel, 67.98 parts of n-butyl acrylate, 30 parts of methyl methacrylate, 2 parts of acrylic acid, 0.02 part of light acrylate 4EG-A, 130 parts of toluene and 0.03 part of AIBN were prepared. Similarly, the reaction is allowed to proceed for 6 hours until the conversion becomes 100%, and the low molecular weight copolymer (B1-B) containing no components having a Tg of −19.9 ° C., a weight average molecular weight of 30,000, and a molecular weight of 150,000 or more. The solution of 7) was obtained (nonvolatile content concentration: 40%).

Next, both copolymer solutions were prepared so that the weight ratio of the high molecular weight component (A1-7) to the low molecular weight component (B1-7) was (A1-7) / (B1-7) = 90/10. Mixing was performed to obtain a copolymer (C6) solution having a Tg of −19.9 ° C., and GPC was measured. The area ratio of the high molecular weight component (A1-7) to the low molecular weight component (B1-7) was (A1-7) / (B1-7) = 90/10.
In addition, Tg was calculated | required except the light acrylate 4EG-A which was trace amount.

<Production Example 8>
The same as in Production Example 2, except that the monomer composition was 82.98 parts of n-butyl acrylate, 15 parts of methyl methacrylate, 1.5 parts of 2-hydroxyethyl methacrylate, and 0.02 parts of light acrylate 4EG-A. The mixture was reacted until the conversion rate became 75% to obtain a mixed solution of a copolymer having a weight average molecular weight of 980,000 and a monomer.
Next, 150 parts of ethyl acetate, 50 parts of toluene, 0.5 part of 2-hydroxyethyl methacrylate and 0.2 part of AIBN were added, and the reaction was further continued for 6 hours until the conversion reached 100%. A solution of the polymer (C8) was obtained.

  The copolymer (C8) shows a continuous peak having a minimum value at a molecular weight of 120,000 in GPC, a high molecular weight component (A2-8) on the higher molecular weight side than this minimum value, and a lower molecular weight than the minimum value. The low molecular weight component (B2-8) on the side, the high molecular weight component (A2-8) has a weight average molecular weight of 1,000,000, the low molecular weight component (B2-8) has a weight average molecular weight of 30,000, both areas The ratio was (A2-8) / (B2-8) = 75/25.

<Production Example 9>
The same as in Production Example 2, except that the monomer composition was 82.98 parts of n-butyl acrylate, 15 parts of methyl methacrylate, 1.5 parts of 2-hydroxyethyl methacrylate, and 0.02 parts of light acrylate 4EG-A. The mixture was reacted until the conversion rate became 75% to obtain a mixed solution of a copolymer having a weight average molecular weight of 950,000 and a monomer.
Subsequently, 200 parts of ethyl acetate, 0.5 part of 2-hydroxyethyl methacrylate, and 0.2 part of AIBN were added, and the reaction was further continued for 6 hours until the conversion reached 100%. A copolymer (C9 ) Was obtained.

  The copolymer (C9) shows a continuous peak having no clear minimum value in GPC, a high molecular weight component (A3-9) on the high molecular weight side having a molecular weight of 150,000 or more, and a low molecular weight having a molecular weight of less than 150,000. Component (B3-9), the weight average molecular weight of the high molecular weight component (A3-9) is 1,000,000, the weight average molecular weight of the low molecular weight component (B3-9) is 80,000, and the area ratio of both is ( A3-9) / (B3-9) = 75/25.

<Comparative Production Example 1>
The monomer composition was reacted until the conversion reached 75% in the same manner as in Production Example 1 except that 99 parts of n-butyl acrylate, 1 part of 4-hydroxybutyl acrylate and 75 parts of acetone were used. A mixed solution of 1.6 million copolymer and monomer was obtained.
Next, 200 parts of toluene, 0.25 part of acrylic acid, and 0.2 part of AIBN were added and reacted in the same manner as in Production Example 1 until the conversion rate reached 100%, and Tg was -54.1 ° C. A solution of the polymer (C10) was obtained.

  The copolymer (CC10) does not contain a polymer having a molecular weight of less than 150,000, has a weight average molecular weight of 1,600,000 and a high molecular weight component (A1-10) having a Tg of −54.3 ° C. and a weight of 150,000 or more. It contained no coalesce and contained a low molecular weight component (B1-10) having a weight average molecular weight of 34,000 and Tg of −53.4 ° C. The high molecular weight component (A1-10) and the low molecular weight component (B1-10) show two independent peaks in the GPC discharge curve, and the area ratio between them is (A1-5) / (B1-5). ) = 75/25.

<Comparative Production Example 2>
In the same manner as in Production Example 1 except that the monomer composition was 58 parts of n-butyl acrylate, 40 parts of methyl methacrylate, and 1.5 parts of acrylic acid, the reaction was carried out until the conversion reached 75%, and the weight average molecular weight was A mixed solution of 1 million copolymer and monomer was obtained.
Subsequently, 200 parts of toluene, 0.5 part of acrylic acid, and 0.2 part of AIBN were added, and the reaction was further carried out until the conversion rate reached 100% in the same manner as in Production Example 1. A solution of C11) was obtained.

  The copolymer (C11) does not contain a polymer having a molecular weight of less than 150,000, has a weight average molecular weight of 1,000,000, a high molecular weight component (A1-11) having a Tg of −7.4 ° C., and a heavy weight having a molecular weight of 150,000 or more. A low molecular weight component (B1-11) having a weight average molecular weight of 25,000 and a Tg of −5.8 ° C. was contained. The high molecular weight component (A1-11) and the low molecular weight component (B1-11) show two independent peaks in the GPC discharge curve, and the area ratio between them is (A1-11) / (B1-11). ) = 75/25.

<Comparative Production Example 3>
In the same manner as in Production Example 1 except that the monomer composition was 76 parts of n-butyl acrylate, 22 parts of methyl methacrylate, and 1.5 parts of acrylic acid, the mixture was reacted for 3.4 hours until the conversion reached 58%. A mixed solution of a copolymer and a monomer having a weight average molecular weight of 1,040,000 was obtained.
Next, 200 parts of toluene, 0.5 part of acrylic acid, and 0.2 part of AIBN were added and reacted in the same manner as in Production Example 1 until the conversion reached 100%, and Tg was -32.4 ° C. A solution of the polymer (C12) was obtained.

  The copolymer (C12) does not contain a polymer having a molecular weight of less than 150,000, has a weight average molecular weight of 1,040,000, a Tg of −32.1 ° C., a high molecular weight component (A1-12), It contained no coalesce and a low molecular weight component (B1-12) having a weight average molecular weight of 30,000 and Tg of −32.9 ° C. The high molecular weight component (A1-12) and the low molecular weight component (B1-12) show two independent peaks in the GPC discharge curve, and the area ratio between them is (A1-12) / (B1-12). ) = 58/42.

<Comparative Production Example 4>
The monomer composition was reacted for 5.5 hours until the conversion reached 90% in the same manner as in Production Example 1 except that 76 parts of n-butyl acrylate, 22 parts of methyl methacrylate and 1.5 parts of acrylic acid were used. A mixed solution of a copolymer having a weight average molecular weight of 1.1 million and a monomer was obtained.
Next, 200 parts of toluene, 0.5 part of acrylic acid, and 0.2 part of AIBN were added and reacted in the same manner as in Production Example 1 until the conversion reached 100%, and Tg was -32.4 ° C. A solution of the polymer (C13) was obtained.

  The copolymer (C13) does not contain a polymer having a molecular weight of less than 150,000, has a weight average molecular weight of 1,100,000, a Tg of −32.1 ° C., a high molecular weight component (A1-13), and a molecular weight of 150,000 or more. A low molecular weight component (B1-13) having a weight average molecular weight of 28,000 and a Tg of −34.9 ° C. was contained. The high molecular weight component (A1-13) and the low molecular weight component (B1-13) show two independent peaks in the GPC discharge curve, and the area ratio between them is (A1-13) / (B1-13). ) = 90/10.

<Comparative Production Example 5>
The monomer composition was reacted for 4.5 hours until the conversion reached 75% in the same manner as in Production Example 1 except that 76 parts of n-butyl acrylate, 22 parts of methyl methacrylate and 1.5 parts of acrylic acid were used. A mixed solution of a copolymer having a weight average molecular weight of 1,000,000 and a monomer was obtained.
Next, 50 parts of acetone, 150 parts of toluene and 0.5 part of acrylic acid are added, and the reaction is further carried out until the conversion becomes 100% in the same manner as in Production Example 1, and the coagulation with Tg of −32.4 ° C. A solution of coalescence (C14) was obtained.

  The copolymer (C14) shows a continuous peak having a minimum value at a molecular weight of 180,000 in GPC, a high molecular weight component (A2-14) on the higher molecular weight side than this minimum value, and a lower molecular weight than the minimum value. Side low molecular weight component (B2-14). The weight average molecular weight of the high molecular weight component (A2-14) is 1,000,000, the weight average molecular weight of the low molecular weight component (B2-14) is 120,000, and the area ratio of both is (A2-14) / (B2-14) = 75/25.

<Comparative Production Example 6>
The monomer composition was 76 parts of n-butyl acrylate, 22 parts of methyl methacrylate, 1.5 parts of acrylic acid, 75 parts of toluene, 25 parts of acetone, 0.03 parts of AIBN, and the same as in Production Example 1, The reaction was carried out until the conversion reached 75% to obtain a mixed solution of a copolymer and a monomer having a weight average molecular weight of 450,000 and a Tg of −32.1 ° C.
Next, 200 parts of toluene, 0.5 part of acrylic acid, and 0.2 part of AIBN were added and reacted in the same manner as in Production Example 1 until the conversion reached 100%, and Tg was -32.4 ° C. A solution of the polymer (C15) was obtained.

  The copolymer (C15) shows a continuous peak having no clear minimum value in GPC, a high molecular weight component (A3-15) on the high molecular weight side having a molecular weight of 150,000 or more, and a low molecular weight having a molecular weight of less than 150,000. And a component (B3-15). The weight average molecular weight of the high molecular weight component (A3-15) is 450,000, the weight average molecular weight of the low molecular weight component (B3-15) is 30,000, and the area ratio of both is (A3-15) / (B3-15) = 75/25.

<Comparative Production Example 7>
The conversion rate is 75 as in Production Example 1 except that the monomer composition is 76 parts of n-butyl acrylate, 22 parts of methyl methacrylate, 1.5 parts of acrylic acid, 50 parts of acetone, and 0.03 part of AIBN. To obtain a mixed solution of a copolymer having a weight average molecular weight of 2.5 million and a monomer.
Next, 200 parts of toluene, 0.5 part of acrylic acid, and 0.2 part of AIBN were added and reacted in the same manner as in Production Example 1 until the conversion reached 100%, and Tg was -32.4 ° C. A solution of the polymer (C16) was obtained.

  The copolymer (C16) does not contain a polymer having a molecular weight of less than 150,000, has a weight average molecular weight of 2.5 million, a Tg of −32.1 ° C., a high molecular weight component (A1-16), and a molecular weight of 150,000 or more. It contained no coalesce and contained a low molecular weight component (B1-16) having a weight average molecular weight of 30,000 and Tg of −33.2 ° C. The high molecular weight component (A1-16) and the low molecular weight component (B1-16) show two independent peaks in the GPC emission curve, and the area ratio between them is (A1-16) / (B1-16). ) = 75/25.

<Comparative Production Example 8>
Production Example 6 except that the monomer composition was 95 parts of n-butyl acrylate, 5 parts of acrylic acid, and 100 parts of ethyl acetate and 0.2 part of benzoyl peroxide instead of 100 parts of acetone and 0.03 parts of AIBN. In the same manner as above, the reaction is carried out for 10 hours until the conversion rate reaches 100%, and a high molecular weight copolymer (A1-17 containing no components having a Tg of −49.3 ° C., a weight average molecular weight of 1,500,000 and a molecular weight of less than 15). ) Was obtained. The obtained copolymer solution was diluted with ethyl acetate to adjust the nonvolatile content concentration to 20%.

  Separately, the monomer composition was 65 parts of n-butyl acrylate, 30 parts of methyl methacrylate, and 5 parts of acrylamide. Instead of 150 parts of toluene and 0.03 parts of AIBN, 100 parts of toluene, 2 parts of AIBN, and n-lauryl mercaptan 2 In the same manner as in Production Example 6 except that the components were changed, the reaction was allowed to proceed for 6 hours until the conversion rate reached 100%, and the Tg was −17.2 ° C., the weight average molecular weight was 10,000 and the molecular weight was not more than 150,000. A solution of the low molecular weight copolymer (B1-17) was obtained. The obtained copolymer solution was diluted with toluene and adjusted to a nonvolatile content concentration of 40%.

Next, both weight ratios of the high molecular weight copolymer (A1-17) and the low molecular weight copolymer (B1-17) are (A1-17) / (B1-17) = 100/150. The copolymer solution was mixed to obtain a copolymer (C17) solution having a Tg of −31.1 ° C.
The copolymer (C17) does not contain a polymer having a molecular weight of less than 150,000, has a weight average molecular weight of 1,500,000 and a high molecular weight component (A1-17) having a Tg of −49.3 ° C., and a heavy weight having a molecular weight of 150,000 or more. A low molecular weight component (B1-17) having a weight average molecular weight of 10,000 and a Tg of −17.2 ° C. was contained. The high molecular weight component (A1-17) and the low molecular weight component (B1-17) show two independent peaks in the GPC discharge curve, and the area ratio between them is (A1-17) / (B1-17). ) = 75/25.
The alkyl methacrylate (a) having no substituent constituting the copolymer (C17) was about 18%.

<Comparative Production Example 9>
The monomer composition was 95 parts of n-butyl acrylate, 5 parts of acrylic acid, and instead of 100 parts of acetone and 0.03 part of AIBN, 0.3 parts of benzoyl peroxide, 40 parts of ethyl acetate, and 60 parts of toluene were used. Was reacted for 10 hours until the conversion rate reached 100% in the same manner as in Production Example 6, and the high molecular weight co-polymer containing no component having a Tg of −49.3 ° C., a weight average molecular weight of 1,000,000 and a molecular weight of less than 15. A combined (A1-18) solution was obtained. The obtained copolymer solution was diluted with ethyl acetate to adjust the nonvolatile content concentration to 20%.

  Separately, Production Example 6 except that the monomer composition was 99 parts methyl methacrylate and 1 part acrylic acid, and instead of 150 parts toluene and 0.03 parts AIBN, AIBN 1 part, ethyl acetate 40 parts, toluene 60 parts Similarly, the reaction is performed for 6 hours until the conversion rate reaches 100%, and the low molecular weight copolymer (B1-18) having a Tg of 105 ° C., a weight average molecular weight of 20,000, and no component having a molecular weight of 150,000 or more. A solution (non-volatile content 50%) was obtained.

Next, both the high molecular weight copolymer (A1-18) and the low molecular weight copolymer (B1-18) were mixed so that the weight ratio was (A1-18) / (B1-18) = 48/52. The polymer solution was mixed to obtain a copolymer (C18) solution having a Tg of 10.5 ° C. When GPC was measured for the copolymer (C18), it had two independent peaks, and the area ratio of the high molecular weight copolymer (A1-18) to the low molecular weight copolymer (B1-18) was ( A1-18) / (B1-18) = 48/52.
The alkyl methacrylate (a) having no substituent constituting the copolymer (C18) was about 51.5%.

<Comparative Production Example 10>
Production Example except that the monomer composition was 98 parts of n-butyl acrylate, 1 part of acrylic acid, 1 part of acrylamide, and 100 parts of ethyl acetate and 0.03 parts of AIBN instead of 100 parts of acetone and 0.03 parts of AIBN. In the same manner as in No. 6, the reaction is allowed to proceed for 8 hours until the conversion reaches 100%, the Tg is -52.3 ° C., the weight average molecular weight is 700,000, and the high molecular weight co-polymer does not contain any component having a molecular weight of less than 100,000. A combined (A3-19) solution was obtained. The obtained copolymer solution was diluted with ethyl acetate to adjust the nonvolatile content concentration to 25%.

Separately, the monomer composition was n-butyl acrylate 86.4 parts, methyl methacrylate 13.6 parts, and instead of toluene 150 parts and AIBN 0.03 parts, ethyl acetate 200 parts, AIBN 0.03 parts In the same manner as in Production Example 6, the reaction is allowed to proceed for 4 hours until the conversion rate reaches 100%, the Tg is −40.7 ° C., the weight average molecular weight is 300,000, A polymer (A3-19 ′) solution was obtained. The obtained copolymer solution was diluted with ethyl acetate to adjust the nonvolatile content concentration to 25%.
Next, both copolymer solutions so that the weight ratio of the high molecular weight copolymer (A3-19) and (A3-19 ′) is (A3-19) / (A3-19 ′) = 100/30. Were mixed to obtain a copolymer (C19) solution having a Tg of −49.7 ° C. The alkyl methacrylate (a) having no substituent constituting the copolymer (C19) was about 3.1%.
The copolymer (C19) shows a continuous peak having no clear minimum value in GPC, and the area ratio between the high molecular weight side and the low molecular weight side with a molecular weight of 150,000 is 83/17, The weight average molecular weight on both sides of the high molecular weight was 550,000, and the weight average molecular weight on the low molecular weight side was 80,000.

<Comparative Production Example 11>
The monomer composition was 95 parts of n-butyl acrylate, 5 parts of acrylic acid, and 100 parts of ethyl acetate and 0.2 parts of AIBN were used instead of 100 parts of acetone and 0.03 parts of AIBN. The polymer is allowed to react for 12 hours until the conversion rate reaches 100%, Tg is −49.3 ° C., the weight average molecular weight is 1,500,000, and the high molecular weight copolymer (A1- 20) A solution was obtained. The obtained copolymer solution was diluted with ethyl acetate to adjust the nonvolatile content concentration to 20%.

  Separately, the monomer composition was 100 parts of n-butyl acrylate, and instead of 150 parts of toluene and 0.03 parts of AIBN, 100 parts of toluene, 5 parts of α-methylstyrene dimer as a chain transfer agent, and 2 parts of AIBN were used. Is the same as in Production Example 6 and is allowed to react for 6 hours until the conversion rate reaches 100%. The low molecular weight copolymer having a Tg of −54 ° C. and a weight average molecular weight of 7000 and containing no component having a molecular weight of 150,000 or more. A combined (B1-20) solution was obtained. The obtained copolymer solution was diluted with toluene, and the non-volatile content concentration was adjusted to 40%.

Next, both copolymer solutions were prepared so that the weight ratio of the high molecular weight copolymer (A1-20) and the low molecular weight copolymer (B1-20) was (A19) / (B19) = 100/100. By mixing, a copolymer (C19) solution having a Tg of −51.7 ° C. was obtained.
The alkyl methacrylate (a) having no substituent constituting the copolymer (C1-20) was 0%. When GPC was measured for the copolymer (C20), it had two independent peaks, and the area ratio of the high molecular weight copolymer (A1-20) to the low molecular weight copolymer (B1-20) was ( A1-20) / (B1-20) = 50/50.

The above production examples are summarized and shown in Tables 1 to 3.
Abbreviations of monomers in Tables 1 to 3 are shown below.
BA: butyl acrylate 2EHA: 2-ethylhexyl acrylate MMA: methyl methacrylate BMA: butyl methacrylate AA: acrylic acid MAA: methacrylic acid 2HEMA: 2-hydroxyethyl methacrylate 4HBA: 4-hydroxybutyl acrylate 4EG-A: light acrylate 4EG-A ( PEG # 200 diacrylate (manufactured by Kyoeisha Chemical Co., Ltd.)
AAm: Acrylamide

In addition, the weight average molecular weight of a copolymer is the weight average molecular weight of polystyrene conversion calculated | required by GPC measurement, and GPC measurement conditions are as follows.
Apparatus: Shodex GPC System-21 (manufactured by Showa Denko KK)
Column: A total of three Shodex KF-602.5 and two Shodex KF-606M (Showa Denko Co., Ltd.) are connected and used.
Solvent: Tetrahydrofuran Flow rate: 0.5 ml / min
Temperature: 40 ° C
Sample concentration: 0.1 wt%
Sample injection volume: 50 μl

<Example 1>
0.2 parts by weight of an active ingredient of an isocyanate curing agent (trimethylolpropane adduct of tolylene diisocyanate; the same shall apply hereinafter) with respect to 100 parts of the solid content of the copolymer (C1) solution obtained in Production Example 1. Silane coupling agent 1 (3-glycidoxypropyltrimethoxysilane; hereinafter the same) was added in an effective amount of 0.1 part and stirred well to obtain a pressure-sensitive adhesive composition (pressure-sensitive adhesive composition). The obtained adhesive composition was subjected to various tests described later.

<Examples 2-3>
Instead of the copolymer (C1) solution, the adhesive composition was prepared in the same manner as in Example 1 except that each of the copolymer (C2) to (C3) solutions obtained in Production Examples 2-3 was used. Obtained and evaluated in the same manner as in Example 1.

<Example 4>
Instead of the copolymer (C1) solution, the copolymer (C4) solution obtained in Production Example 4 was used. The isocyanate-based curing agent was 0.15 part as an active ingredient, and the epoxy-based curing agent 1 (N, N , N ′, N′-tetraglycidyl-m-xylenediamine; hereinafter the same) was used in the same manner as in Example 1 except that 0.05 part was used as an active ingredient. And evaluated in the same manner.

<Examples 5-9>
Instead of the copolymer (C1) solution, the adhesive composition was prepared in the same manner as in Example 1 except that each of the copolymer (C5) to (C9) solutions obtained in Production Examples 5 to 9 was used. Obtained and evaluated in the same manner as in Example 1.

<Comparative Example 1>
With respect to 100 parts of the solid content of the copolymer (C10) solution obtained in Comparative Production Example 1, 0.05 part of the isocyanate curing agent and 0.1 part of the silane coupling agent 1 as the active ingredient are used. Was added and stirred well to obtain an adhesive composition. When evaluated in the same manner as in Example 1, foaming occurred in the heat resistance test and the moist heat resistance test.

<Comparative Examples 2-7>
Adhesive composition in the same manner as in Example 1, except that the copolymers (C11) to (C16) solutions obtained in Comparative Production Examples 2 to 7 were used instead of the copolymer (C1) solution, respectively. And evaluated in the same manner as in Example 1.

<Comparative Example 8>
To 250 parts of the solid content of the copolymer (C17) solution obtained in Comparative Production Example 8, 0.02 part of the epoxy curing agent 1 as an active ingredient is added and stirred well to obtain an adhesive composition. It was.
When the obtained pressure-sensitive adhesive composition was evaluated in the same manner as in Example 1, the substrate adhesion was remarkably poor, and remarkable foaming was observed in the heat resistance test and the moist heat resistance test.

<Comparative Example 9>
To 100 parts of the solid content of the copolymer (C18) solution obtained in Comparative Production Example 9, 0.05 part of epoxy curing agent 2 (ethylene glycol diglycidyl ether; the same applies hereinafter) is added as an active ingredient. The adhesive composition was obtained by stirring well.
When the obtained pressure-sensitive adhesive composition was evaluated in the same manner as in Example 1, the substrate adhesion and reworkability were remarkably poor, a light leakage phenomenon occurred, and remarkable foaming was observed in the heat resistance test and the moist heat resistance test. It was.

<Comparative Example 10>
To 130 parts of the solid content of the copolymer (C19) solution obtained in Comparative Production Example 10, 0.6 parts of epoxy curing agent 1 is added as an active ingredient and stirred well to obtain an adhesive composition. It was.
As a result of evaluating the obtained pressure-sensitive adhesive composition in the same manner as in Example 1, the substrate adhesion and reworkability were extremely poor.

<Comparative Example 11>
An ethyleneimine-based curing agent (trimethylolpropane tri-β-aziridinylpropionate) was added as an active ingredient to the solid content of 200 parts of the copolymer (C20) solution obtained in Comparative Production Example 11. 25 parts, 2.5 parts phenolic compound (3,5-di-t-butyl-4-hydroxy-benzylphosphonate-diethyl ester) as an active ingredient as an antioxidant, and silane coupling agent 2 (3- 1 part of aminopropyltrimethoxysilane) was added as an active ingredient and stirred well to obtain an adhesive composition.
As a result of evaluating the obtained adhesive composition in the same manner as in Example 1, the substrate adhesion and reworkability were remarkably poor, and foaming was observed in the heat resistance test and the moist heat resistance test.

<Comparative Example 12>
A pressure-sensitive adhesive composition was obtained in the same manner as in Example 1 except that the epoxy-based curing agent 1 was used instead of the isocyanate-based curing agent, and evaluated in the same manner as in Example 1. As a result of evaluation, the substrate adhesion was remarkably poor.

Various tests were conducted as follows.
<Base material adhesion and reworkability>
The pressure-sensitive adhesive composition obtained in each Example and each Comparative Example was applied to a polyester release film (thickness 38 μm) and dried at 100 ° C. for 2 minutes to form a pressure-sensitive adhesive layer having a thickness of 25 μm. A polarizing film (thickness: 180 μm) was bonded to the obtained adhesive layer, and the reaction was allowed to proceed for 7 days in an atmosphere of 23 ° C. and 50% RH (aging) to obtain an adhesive film 1.
The obtained pressure-sensitive adhesive film 1 is cut to a width of 25 mm, the release film is peeled off, and the exposed pressure-sensitive adhesive layer is attached to a glass plate having a thickness of 0.7 mm in an atmosphere of 23 ° C. and 50% RH. After holding and bonding for 15 minutes under a pressure of 5 kg / cm ² , roll pressure bonding was performed according to JIS Z 0237.

After 24 hours of pressure bonding, the mixture was left at 80 ° C. for 500 hours. Thereafter, the polarizing film was peeled off from the glass plate at a peel rate of 180 ° C. and a pulling speed of 300 mm / min using a peel tester in an atmosphere of 23 ° C. and 50% RH, and the glass plate surface and the adhesive layer surface were visually observed. . The evaluation criteria are as follows.
4: The pressure-sensitive adhesive layer is not transferred to the glass plate surface at all, and the pressure-sensitive adhesive layer surface is also smooth.
3: The pressure-sensitive adhesive layer is not transferred to the glass plate surface, but slight unevenness is generated on the surface of the pressure-sensitive adhesive layer.
2: A part of the pressure-sensitive adhesive layer has been transferred to the surface of the glass plate, and the surface of the pressure-sensitive adhesive layer is also significantly uneven.
1: The adhesive layer has completely transferred to the glass plate surface.

<Light leakage phenomenon>
The adhesive composition obtained in each Example and each Comparative Example was applied to a polyester release film (thickness: 38 μm) and dried at 90 ° C. for 60 seconds to form an adhesive layer having a thickness of 25 μm. A polarizing film (thickness: 180 μm) was bonded to the obtained adhesive layer, and the reaction was allowed to proceed for 7 days in an atmosphere of 23 ° C. and 50% RH (aging). The pressure-sensitive adhesive film 2 was obtained by cutting into 200 mm × 200 mm so that the axial direction of the absorption axis of the polarizing film was at an angle of 45 ° with respect to the side.
The release film of the adhesive film 2 is peeled off, and the exposed adhesive layer is placed on both surfaces of a 0.7 mm thick glass plate so that the axial directions of the absorption axes of the respective polarizing films are orthogonal to each other in a 50 ° C. atmosphere. After applying pressure of 5 kg / cm ² and holding for 15 minutes, bonding was carried out for 500 hours in an atmosphere at 80 ° C. and then returned to room temperature, and the presence or absence of light leakage from the four corners or peripheral edges was observed. . The evaluation criteria are as follows.
4: No light leakage is observed.
3: Almost no light leakage is observed.
2: Light leakage is slightly noticeable.
1: Light leakage is very remarkable.

<Heat resistance and moist heat resistance>
The release film of the adhesive film 2 described in the light leakage phenomenon is peeled off, and the exposed adhesive layer is subjected to a pressure of 5 kg / cm ² in a 50 ° C. atmosphere on one side of a 0.7 mm thick glass plate for 15 minutes. After holding and bonding, the substrate was left in an atmosphere at 80 ° C. for 500 hours (heat resistance test).
Separately, the adhesive film 2 and the glass plate were bonded together in the same manner, and then left in a constant temperature and humidity chamber at 60 ° C. and 90% RH for 500 hours (moisture and heat resistance test).
After standing, the temperature was returned to room temperature, and the adhesive film 2 was observed to float, peel and foam.

“Foaming” is a state in which relatively large bubbles are generated at the interface (other than the peripheral edge) between the adhesive layer and the glass.
The “floating / peeling” is a state where the adhesive film 2 is lifted from the glass and peeled off. Each evaluation standard is as follows.
4: Not generated.
3: Minor occurrence is observed.
2: Occurrence is observed.
1: Significant occurrence is observed.
The above evaluation results are shown in Tables 4-6.

Abbreviations in Tables 4 to 6 are as follows.
Isocyanate-based curing agent: trimethylolpropane adduct of tolylene diisocyanate Epoxy-based curing agent 1: N, N, N ′, N′-tetraglycidyl-m-xylenediamine Epoxy-based curing agent 2: ethylene glycol diglycidyl ether Ethyleneimine curing agent: trimethylolpropane tri-β-aziridinylpropionate Antioxidant: 3,5-di-t-butyl-4-hydroxy-benzylphosphonate-diethyl ester Silane coupling agent 1: 3- Glycidoxypropyltrimethoxysilane Silane coupling agent 2: 3-aminopropyltrimethoxysilane

The disclosure of the present application is related to the subject matter described in Japanese Patent Application No. 2006-243715 filed on Sep. 8, 2006, the entire contents of which are incorporated herein by reference.
It should be noted that various modifications and changes may be made to the above-described embodiments without departing from the novel and advantageous features of the present invention other than those already described. Accordingly, all such modifications and changes are intended to be included within the scope of the appended claims.

Claims (7)

A pressure-sensitive adhesive containing a copolymer (C) having a hydroxyl group and / or a carboxyl group and having a glass transition temperature of −60 to 0 ° C. and an isocyanate curing agent (D),
The copolymer (C) is
(1) Alkyl methacrylate having no substituent (a): 15 to 35% by weight, alkyl acrylate having no substituent (b), and other ethylenic copolymerizable with the above (a) and (b) Radical copolymerization of a monomer (c) having a saturated double bond and comprising a monomer (c1) having a hydroxyl group and / or a carboxyl group and an ethylenically unsaturated double bond (Provided that the total of (a) to (c) is 100% by weight),
(2) including a high molecular weight component (A) and a low molecular weight component (B),
(2-1) A peak of a high molecular weight component (A1) having a weight average molecular weight of 500,000 to 2,200,000 completely independent on an emission curve in gel permeation chromatography and a low weight average molecular weight of 1,000 to 100,000 The area ratio between the peak of the high molecular weight component (A1) and the peak of the low molecular weight component (B1) is (A1) / (B1) = 60/40 to 90 / 10 or
(2-2) The peak of the high molecular weight component (A2) having a weight average molecular weight of 500,000 to 2,200,000 and the weight average molecular weight of 1,000 to 100,000 located on both sides of the minimum value of the discharge curve in gel permeation chromatography The area ratio of the peak of the high molecular weight component (A2) and the peak of the low molecular weight component (B2) is (A2) / (B2) = 60/40 to 90-3, or (2-3) In gel permeation chromatography, a peak of a high molecular weight component (A3) consisting of polymer molecules having a molecular weight of 150,000 or more and having a weight average molecular weight of 500,000 to 2,200,000 And a peak of a low molecular weight component (B3) consisting of polymer molecules having a molecular weight of less than 150,000 and having a weight average molecular weight of 1,000 to 100,000, and the high molecular weight component (A3) peak, The area ratio to the low molecular weight component (B3) peak is (A3) / (B3) = 60/40 to 90/10.
A pressure-sensitive adhesive.   The alkyl group of the alkyl methacrylate (a) having no substituent has 1 to 6 carbon atoms, and the alkyl group is selected from the group consisting of a linear alkyl group, a chain alkyl group having a branched structure, and a cyclic alkyl group The pressure-sensitive adhesive according to claim 1, which is at least one kind.   The pressure-sensitive adhesive according to claim 1 or 2, comprising 0.01 to 10 parts by weight of an isocyanate curing agent (D) with respect to 100 parts by weight of the copolymer (C).   Copolymer (C) is alkyl methacrylate (a) having no substituent: 15 to 35% by weight, alkyl acrylate (b) having no substituent, and other copolymerizable with the above (a) and (b) A monomer (c) having an ethylenically unsaturated double bond, the monomer (c) comprising a monomer (c1) having a hydroxyl group and / or a carboxyl group and an ethylenically unsaturated double bond; Then, radical copolymerization is carried out until the polymerization conversion becomes 60 to 90% to synthesize a copolymer containing a high molecular weight component having a weight average molecular weight of 500,000 to 2,200,000, and then a monomer (c) is required. The pressure-sensitive type according to any one of claims 1 to 3, which is obtained by further radical copolymerization of the (a) to (c) until the polymerization conversion rate is 80 to 100%. adhesive. A method for producing a pressure-sensitive adhesive comprising the following (I) to (III):
(I) Alkyl methacrylate having no substituent (a): 15 to 35% by weight, alkyl acrylate (b) having no substituent and other ethylenically unsaturated dialkylates copolymerizable with the above (a) and (b) A monomer (c) having a heavy bond and comprising a monomer (c1) having a hydroxyl group and / or a carboxyl group and an ethylenically unsaturated double bond is converted into a polymerization conversion ratio. Radical copolymerization to 60-90% to obtain a copolymer containing a high molecular weight component having a weight average molecular weight of 500,000-2,200,000;
(II) Next, the monomer (c) is added as necessary, and the above (a) to (c) are further radically copolymerized until the polymerization conversion rate becomes 80 to 100% (however, (a) to ( c) is 100% by weight),
(2-1) A peak of a high molecular weight component (A1) having a weight average molecular weight of 500,000 to 2,200,000 completely independent on an emission curve in gel permeation chromatography and a low weight average molecular weight of 1,000 to 100,000 The area ratio between the peak of the high molecular weight component (A1) and the peak of the low molecular weight component (B1) is (A1) / (B1) = 60/40 to 90 / 10 or
(2-2) The peak of the high molecular weight component (A2) having a weight average molecular weight of 500,000 to 2,200,000 and the weight average molecular weight of 1,000 to 100,000 located on both sides of the minimum value of the discharge curve in gel permeation chromatography The area ratio of the peak of the high molecular weight component (A2) and the peak of the low molecular weight component (B2) is (A2) / (B2) = 60/40 to 90-3, or (2-3) In gel permeation chromatography, a peak of a high molecular weight component (A3) consisting of polymer molecules having a molecular weight of 150,000 or more and having a weight average molecular weight of 500,000 to 2,200,000 And a peak of a low molecular weight component (B3) consisting of polymer molecules having a molecular weight of less than 150,000 and having a weight average molecular weight of 1,000 to 100,000, and the high molecular weight component (A3) peak, The area ratio to the low molecular weight component (B3) peak is (A3) / (B3) = 60/40 to 90/10.
A copolymer (C) comprising a high molecular weight component (A) and a low molecular weight component (B), having a hydroxyl group and / or a carboxyl group, and having a glass transition temperature of -60 to 0 ° C Obtaining (C); and (III) mixing the copolymer (C) and the isocyanate curing agent (D).   A pressure-sensitive adhesive obtained by the production method according to claim 5.   An optical film selected from the group consisting of a polarizing film and a retardation film, and a pressure-sensitive adhesive layer provided on at least one surface of the optical film, wherein the optical film is any one of claims 1 to 4 or claim 6. A pressure-sensitive adhesive film comprising a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive.