WO2015146410A1

WO2015146410A1 - Temperature-sensitive adhesive

Info

Publication number: WO2015146410A1
Application number: PCT/JP2015/054989
Authority: WO
Inventors: 隆史惠; 伸一郎河原
Original assignee: ニッタ株式会社
Priority date: 2014-03-25
Filing date: 2015-02-23
Publication date: 2015-10-01
Also published as: JP6546910B2; TW201542743A; KR20160137994A; CN106133102B; JPWO2015146410A1; TWI663237B; CN106133102A; KR102281487B1

Abstract

This temperature-sensitive adhesive contains a first side-chain crystalline polymer, has an adhesive strength that decreases at temperatures less than the melting point of the first side-chain crystalline polymer, and further contains a second side-chain crystalline polymer having a weight average molecular weight that is smaller than the first side-chain crystalline polymer. This makes it possible to obtain the effect of having heat resistance such that glass, etc. can be secured even in a high-temperature atmosphere (e.g. 200 °C or more), and of enabling separation of the secured glass, etc. when cooled from the high-temperature atmosphere and exposed to a low-temperature atmosphere.

Description

Temperature sensitive adhesive

The present invention has heat resistance capable of fixing glass or the like even in a high temperature atmosphere (for example, 200 ° C. or higher), and peels off the fixed glass or the like when cooled from a high temperature atmosphere and exposed to a low temperature atmosphere. It is related with the temperature sensitive adhesive which can be performed.

In the manufacturing process of touch panels, organic EL elements (OLEDs), etc., in order to efficiently process the substrate, the substrate may be fixed using an adhesive, an adhesive sheet, an adhesive tape, or the like. For example, Patent Document 1 describes a pressure-sensitive adhesive sheet containing a predetermined tackifier and a side chain crystalline polymer.

By the way, in the manufacturing process of touch panels, organic EL elements, etc., there is a process of exposing a substrate to a high temperature atmosphere of 200 ° C. or higher. For example, when a plastic substrate is fixed to a glass pedestal using a conventional adhesive sheet or the like, the substrate can be peeled from the pedestal even after being exposed to high temperature conditions.

However, when a glass substrate is fixed to a glass pedestal using a conventional adhesive sheet or the like, the adhesion of the adhesive component to the glass increases when exposed to a high temperature atmosphere, and the substrate is peeled off from the pedestal. It becomes difficult. Moreover, even if it is difficult to peel, if it is a flexible film-like substrate, it can be bent and peeled, for example, so as to wind up the substrate, but in the case of a glass substrate, it cannot be bent and peeled. As described above, the conventional pressure-sensitive adhesive, pressure-sensitive adhesive sheet, pressure-sensitive adhesive tape and the like did not assume that the glass substrate is fixed to the glass base.

JP 2012-102212 A

An object of the present invention is to have heat resistance capable of fixing glass or the like even in a high-temperature atmosphere (for example, 200 ° C. or higher), and to fix the glass when cooled from a high-temperature atmosphere and exposed to a low-temperature atmosphere. It is to provide a temperature-sensitive adhesive that can be peeled off.

The temperature-sensitive adhesive of the present invention contains a first side chain crystalline polymer, and the adhesive force decreases at a temperature lower than the melting point of the first side chain crystalline polymer. A second side chain crystalline polymer having a small weight average molecular weight.

According to the temperature-sensitive adhesive of the present invention, it has heat resistance capable of fixing glass or the like even in a high temperature atmosphere (for example, 200 ° C. or more), and when it is cooled from a high temperature atmosphere and exposed to a low temperature atmosphere In addition, the effect that the fixed glass or the like can be peeled off is obtained.

It is a schematic diagram for demonstrating the measuring method of the peeling strength in an Example.

<Temperature sensitive adhesive>
Hereinafter, the temperature-sensitive adhesive according to an embodiment of the present invention will be described in detail. The temperature-sensitive adhesive of this embodiment contains a first side chain crystalline polymer and a second side chain crystalline polymer having a smaller weight average molecular weight than the first side chain crystalline polymer.

The “side chain crystalline polymer” is a polymer having a melting point. Here, the “melting point” is a temperature at which a specific portion of a polymer that is initially aligned in an ordered arrangement becomes disordered by a certain equilibrium process, and is determined using a differential thermal scanning calorimeter (DSC). It means a value obtained by measurement under the measurement conditions of ° C / min.

The side chain crystalline polymer is crystallized at a temperature lower than the above-mentioned melting point, and undergoes phase transition at a temperature higher than the melting point to exhibit fluidity. That is, the side chain crystalline polymer has temperature sensitivity because it reversibly becomes a crystalline state or a fluidized state in accordance with a temperature change. When the side-chain crystalline polymer is cooled to below the melting point, it crystallizes and the adhesive strength decreases. On the other hand, the side chain crystalline polymer exhibits fluidity when heated to the melting point or higher, so that the adhesive strength is recovered. As a result, the temperature-sensitive adhesive of this embodiment can be used repeatedly.

(First side chain crystalline polymer)
The first side chain crystalline polymer contained in the temperature-sensitive adhesive of the present embodiment is not particularly limited as long as it is a side chain crystalline polymer, and has, for example, a linear alkyl group having 16 or more carbon atoms (meta ) A polymer obtained by polymerizing a monomer component containing acrylate. “(Meth) acrylate” means “acrylate” or “methacrylate”. This straight-chain alkyl group having 16 or more carbon atoms functions as a side chain crystalline part in the side chain crystalline polymer. That is, the side chain crystalline polymer is a comb polymer having a linear alkyl group having 16 or more carbon atoms in the side chain, and the side chain is aligned and ordered in an ordered arrangement by intermolecular force or the like.

Examples of the (meth) acrylate having a linear alkyl group having 16 or more carbon atoms include 16 to 16 carbon atoms such as cetyl (meth) acrylate, stearyl (meth) acrylate, eicosyl (meth) acrylate, and behenyl (meth) acrylate. (Meth) acrylate having 22 linear alkyl groups. This (meth) acrylate may use only 1 type and may use 2 or more types together. This (meth) acrylate is preferably contained in the monomer component in a proportion of 10 to 90% by weight, more preferably 20 to 80% by weight.

The monomer component may contain another monomer that can be copolymerized with a (meth) acrylate having a linear alkyl group having 16 or more carbon atoms. Examples of other monomers include polar monomers and (meth) acrylates having an alkyl group other than a linear alkyl group having 16 or more carbon atoms.

Examples of polar monomers include ethylenically unsaturated monomers having a carboxyl group such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid; 2-hydroxyethyl (meth) acrylate, 2-hydroxy Examples thereof include ethylenically unsaturated monomers having a hydroxyl group such as propyl (meth) acrylate and 2-hydroxyhexyl (meth) acrylate. These polar monomers may be used alone or in combination of two or more. The polar monomer is preferably contained in the monomer component in an amount of 20% by weight or less, more preferably 1 to 15% by weight.

Examples of the (meth) acrylate having an alkyl group other than a linear alkyl group having 16 or more carbon atoms include (meth) acrylates having an alkyl group having 1 to 6 carbon atoms, such as methyl (meth) acrylate, ethyl ( Examples include meth) acrylate, butyl (meth) acrylate, and hexyl (meth) acrylate. This (meth) acrylate may use only 1 type and may use 2 or more types together. This (meth) acrylate is preferably contained in the monomer component in a proportion of 10 to 90% by weight, more preferably 20 to 80% by weight.

Furthermore, the monomer component may contain a reactive fluorine compound. The reactive fluorine compound means a fluorine compound having a reactive functional group. Examples of reactive functional groups include vinyl groups, allyl groups, (meth) acryl groups, (meth) acryloyl groups, (meth) acryloyloxy groups and other groups having an ethylenically unsaturated double bond; epoxy groups ( Glycidyl group and epoxycycloalkyl group), mercapto group, carbinol group (methylol group), carboxyl group, silanol group, phenol group, amino group, hydroxyl group and the like.

Specific examples of the reactive fluorine compound include compounds represented by the following general formula (I).

In the formula, R ₁ represents CH ₂ ═CHCOOR ₂ — or CH ₂ ═C (CH ₃ ) COOR ₂ —. R ₂ represents an alkylene group.

Examples of the alkylene group include linear or branched alkylene groups having 1 to 6 carbon atoms such as a methylene group, an ethylene group, a trimethylene group, a propylene group, a tetramethylene group, a pentamethylene group, and a hexamethylene group.

Specific examples of the compound represented by the general formula (I) include 2,2,2-trifluoroethyl acrylate represented by the following formula (Ia), 2,2,2- Examples thereof include trifluoroethyl methacrylate.

As the reactive fluorine compound, a commercially available product may be used. For example, “Biscoat 3F”, “Biscoat 3FM”, “Biscoat 4F”, “Biscoat 8F”, “Biscoat 8FM” (all are Osaka Organic Chemical Industries, Ltd.) And “Light Ester M-3F” (manufactured by Kyoeisha Chemical Co., Ltd.) are commercially available.

Only one type of reactive fluorine compound may be used, or two or more types may be used in combination. Furthermore, the reactive fluorine compound is preferably contained in the monomer component in a proportion of 10% by weight or less, more preferably 5% by weight or less.

The preferred composition of the first side chain crystalline polymer is 28 to 34% by weight of behenyl acrylate, 54 to 64% by weight of methyl acrylate, 4 to 6% by weight of acrylic acid, and 2,2,2 represented by the formula (Ia) The amount of 2-trifluoroethyl acrylate is 4 to 6% by weight. Other preferred compositions of the first side chain crystalline polymer include stearyl acrylate 26-30 wt%, methyl acrylate 58-66 wt%, acrylic acid 4-6 wt%, and 2, 2,2-trifluoroethyl acrylate is 4 to 6% by weight. The first side chain crystalline polymer preferably has the highest proportion of methyl acrylate among the monomer components.

The polymerization method of the monomer component is not particularly limited, and examples thereof include a solution polymerization method, a bulk polymerization method, a suspension polymerization method, and an emulsion polymerization method. For example, when the solution polymerization method is adopted, the monomer component and the solvent are mixed, and if necessary, a polymerization initiator and a chain transfer agent are added, and the reaction is performed at about 40 to 90 ° C. for about 2 to 10 hours while stirring. You can do it.

The weight average molecular weight of the first side chain crystalline polymer is not particularly limited, and is preferably larger than 100,000, more preferably 300,000 to 800,000, still more preferably 400,000 to 700,000. The weight average molecular weight is a value obtained by measuring by gel permeation chromatography (GPC) and converting the obtained measurement value to polystyrene.

The first side-chain crystalline polymer contained in the temperature-sensitive adhesive of the present embodiment preferably has a melting point of 10 to 60 ° C., for example, considering fixing and peeling in the substrate processing process, and 20 to 60 ° C. It is more preferable to have a melting point of If the melting point is such a temperature, the adherend can be reliably fixed because the temperature-sensitive adhesive has adhesiveness in a process under a high-temperature atmosphere for substrate processing. On the other hand, when cooling to peel off the adherend, it is possible to cool to a temperature below the melting point with relatively little cooling energy. The melting point can be adjusted by changing the composition of the monomer component.

(Second side chain crystalline polymer)
The 2nd side chain crystalline polymer contained in the temperature sensitive adhesive of this embodiment will not be specifically limited if it has a weight average molecular weight smaller than a 1st side chain crystalline polymer.

When the conventional temperature-sensitive adhesive is fixed to the adherend and exposed to a high-temperature atmosphere, the temperature-sensitive adhesive becomes flexible and follows the uneven shape present on the surface of the adherend. For this reason, when cooled, a so-called anchor effect appears, and the adhesive force of the temperature-sensitive adhesive becomes higher than the initial adhesive force, resulting in poor peeling.

The second side-chain crystalline polymer reduces the wettability of the temperature-sensitive adhesive to the adherend in a high-temperature atmosphere and makes it difficult for the temperature-sensitive adhesive to follow the uneven shape present on the surface of the adherend. Inferred. As a result, the anchor effect can be suppressed and the peelability is improved.

The second side chain crystalline polymer is also basically obtained by the same method as the first side chain crystalline polymer. That is, a monomer component including (meth) acrylate having a linear alkyl group having 16 or more carbon atoms, a polar monomer, (meth) acrylate having an alkyl group other than a linear alkyl group having 16 or more carbon atoms, and the like. It is obtained by polymerizing by the above-mentioned solution polymerization method, bulk polymerization method, suspension polymerization method, emulsion polymerization method or the like. The above-mentioned reactive fluorine compound may be included in the monomer component as necessary.

In the polymerization reaction of the second side chain crystalline polymer, in order to reduce the weight average molecular weight as compared with the first side chain crystalline polymer, for example, a polymerization initiator or a chain transfer agent than the polymerization reaction of the first side chain crystalline polymer. What is necessary is just to adjust to the desired weight average molecular weight, for example by increasing the addition amount. The weight average molecular weight of the second side chain crystalline polymer is preferably 100,000 or less, more preferably 4000 to 100,000, still more preferably 4000 to 40000, and still more preferably 5000 to 30000.

The second side chain crystalline polymer is preferably 1 to 20 parts by weight, more preferably 1 to 15 parts by weight, still more preferably 1 to 10 parts by weight, based on 100 parts by weight of the first side chain crystalline polymer. Preferably it is contained in a proportion of 1 to 5 parts by weight.

The preferred composition of the second side chain crystalline polymer is 33 to 47% by weight of behenyl acrylate, 32 to 38% by weight of stearyl acrylate, 17 to 23% by weight of methyl acrylate, and 4 to 6% by weight of acrylic acid. The second side chain crystalline polymer preferably has the highest proportion of behenyl acrylate among the monomer components.

(Tackifier)
The temperature-sensitive adhesive of this embodiment may further contain a tackifier as necessary. Examples of the tackifier include rosin resins, terpene resins, hydrocarbon resins, epoxy resins, polyamide resins, phenol resins, and ketone resins, and are not particularly limited. Only 1 type may be used for a tackifier and it may use 2 or more types together. Among these, a rosin resin is preferable from the viewpoint of compatibility with the first side chain crystalline polymer and the second side chain crystalline polymer.

The softening point of the tackifier is not particularly limited, and is, for example, about 50 to 250 ° C., preferably about 90 to 200 ° C. When the softening point is 90 to 140 ° C., preferably 90 to 110 ° C., the peelability tends to be improved. The softening point is measured according to the ring and ball method defined in JIS K 5902.

Examples of rosin resins include rosin derivatives. Examples of rosin derivatives include rosin ester compounds obtained by esterifying unmodified rosin (raw rosin) such as gum rosin, wood rosin and tall oil rosin with alcohols, or modified rosins such as hydrogenated rosin, disproportionated rosin and polymerized rosin. Ester compounds such as modified rosin esterified with alcohols; metal salts of rosins such as unmodified rosin, modified rosin and various rosin derivatives; phenols on unmodified rosin, modified rosin and various rosin derivatives Examples thereof include a rosin phenol resin obtained by addition with an acid catalyst and thermal polymerization.

Among these rosin derivatives, ester compounds of rosin are preferable. For example, “Superester A-100”, “Superester A-125”, “Pencel D-160” (all manufactured by Arakawa Chemical Co., Ltd.), etc. Is commercially available.

Examples of tackifiers other than rosin ester compounds include rosin-modified special synthetic resins “Hari Star KT-3” and “Hari Star DS-90” (manufactured by Harima Chemical Co., Ltd.), and alicyclic saturated hydrocarbons. Resin “Alcon P-100” (manufactured by Arakawa Chemical Industries, Ltd.) is commercially available.

The tackifier is contained in an amount of preferably 200 parts by weight or less, more preferably 150 parts by weight or less, and still more preferably 100 parts by weight or less with respect to 100 parts by weight of the first side chain crystalline polymer. When the content of the tackifier is preferably 5 to 40 parts by weight, more preferably 15 to 35 parts by weight, still more preferably 25 to 35 parts by weight, based on 100 parts by weight of the first side chain crystalline polymer. The peelability tends to improve.

(Crosslinking agent)
The temperature-sensitive adhesive of this embodiment may contain a crosslinking agent as long as the effects of this embodiment are not impaired. For example, the crosslinking agent is used to crosslink the first side chain crystalline polymers, the second side chain crystalline polymers, or the first side chain crystalline polymer and the second side chain crystalline polymer. Examples of the crosslinking agent include metal chelate compounds, aziridine compounds, isocyanate compounds, and epoxy compounds. Among these, a metal chelate compound is preferable in terms of further improving heat resistance. The crosslinking reaction is performed by adding a crosslinking agent and heating at 90 to 110 ° C. for about 1 to 20 minutes.

Examples of metal chelate compounds include acetylacetone coordination compounds of polyvalent metals, acetoacetate coordination compounds of polyvalent metals, and the like. Examples of the polyvalent metal include aluminum, nickel, chromium, iron, titanium, zinc, cobalt, manganese, and zirconium. Only 1 type may be used for a metal chelate compound and it may use 2 or more types together. Among these, an acetylacetone coordination compound or acetoacetate coordination compound of aluminum is preferable, and aluminum trisacetylacetonate is more preferable.

The crosslinking agent is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 15 parts by weight, and still more preferably 1 to 15 parts by weight with respect to 100 parts by weight of the first side chain crystalline polymer. included. When a metal chelate compound is employed as the cross-linking agent, the metal chelate compound is preferably 0.1 to 20 parts by weight, more preferably 5 to 12 parts by weight, more preferably 100 parts by weight of the first side chain crystalline polymer. Preferably, it is contained at a ratio of 8 to 12 parts by weight.

The usage method of the temperature-sensitive adhesive of the present embodiment is not particularly limited, and the temperature-sensitive adhesive may be used as it is, and a temperature-sensitive adhesive and a solvent are mixed and used as necessary. Also good. Alternatively, as described below, the thermosensitive adhesive of this embodiment may be processed into a thermosensitive adhesive sheet, a thermosensitive adhesive tape, or the like.

<Temperature sensitive adhesive sheet>
As a temperature-sensitive adhesive sheet, for example, a base-less sheet-like form can be mentioned. Such a baseless temperature-sensitive adhesive sheet is obtained by, for example, applying the temperature-sensitive adhesive of the present embodiment to a release film (such as a polyethylene terephthalate film coated with a release agent such as silicone), and heating. (Crosslinked) to obtain. Usually, after the application of the temperature-sensitive adhesive, a release film is further stuck on the temperature-sensitive adhesive, so that the temperature-sensitive adhesive sheet is sandwiched between the release films. The release film preferably has a thickness of 5 to 500 μm, more preferably 25 to 250 μm, and is peeled off when the temperature-sensitive adhesive sheet is used. The temperature-sensitive adhesive sheet preferably has a thickness of 5 to 200 μm, more preferably 10 to 100 μm.

Application method is not particularly limited, and examples thereof include a method in which a temperature-sensitive adhesive and a solvent are mixed to prepare a coating solution, and the coating solution is applied with a coater or the like. Examples of the coater include a knife coater, a roll coater, a calendar coater, a comma coater, a gravure coater, and a rod coater.

<Temperature sensitive adhesive tape>
When the temperature-sensitive adhesive of this embodiment is used as a temperature-sensitive adhesive tape, the pressure-sensitive adhesive layer made of the temperature-sensitive adhesive of this embodiment is placed on at least one surface of a film-like or sheet-like substrate. What is necessary is just to laminate. Examples of the base material include polyethylene, polyethylene terephthalate, polypropylene, polyester, polyamide, polyimide, polycarbonate, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-propylene copolymer, and polyvinyl chloride. Examples include synthetic resin base materials.

The substrate may have either a single layer structure or a multilayer structure, and usually has a thickness of about 5 to 500 μm, preferably about 25 to 250 μm. The substrate may be subjected to surface treatment such as corona discharge treatment, plasma treatment, blast treatment, chemical etching treatment, primer treatment, etc., in order to improve the adhesion to the adhesive layer.

As a method for laminating the pressure-sensitive adhesive layer on the substrate, as described above, a temperature-sensitive pressure-sensitive adhesive and a solvent are mixed to prepare a coating solution, and the coating solution may be applied with a coater or the like. The pressure-sensitive adhesive layer preferably has a thickness of 5 to 60 μm, more preferably 10 to 60 μm, and still more preferably 10 to 50 μm.

When the pressure-sensitive adhesive layers are laminated on both surfaces of the base material, the thickness of each pressure-sensitive adhesive layer may be the same or different. The composition of the temperature sensitive adhesive forming each adhesive layer may be the same or different. Furthermore, if the pressure-sensitive adhesive layer made of the temperature-sensitive pressure-sensitive adhesive of this embodiment is laminated on one surface, the other surface is a pressure-sensitive adhesive other than the temperature-sensitive pressure-sensitive adhesive of this embodiment (for example, a pressure-sensitive pressure-sensitive adhesive). The adhesive layer which consists of may be laminated | stacked. Examples of the pressure-sensitive adhesive include natural rubber-based adhesives, synthetic rubber-based adhesives, styrene-butadiene latex-based adhesives, acrylic adhesives, and the like.

Furthermore, a release film is usually laminated on the surface of the pressure-sensitive adhesive layer of the temperature-sensitive adhesive tape, and this release film is peeled off when the temperature-sensitive adhesive tape is used. As the release film, the release film described in the above temperature-sensitive adhesive sheet is used.

The temperature-sensitive adhesive of the present embodiment has heat resistance capable of fixing glass or the like even in a high temperature atmosphere (for example, 200 ° C. or higher), and when cooled from a high temperature atmosphere and exposed to a low temperature atmosphere. The effect of being able to peel fixed glass and the like is exhibited. For example, the temperature-sensitive adhesive of this embodiment has a glass-glass peel strength at 5 ° C. after exposure to a high temperature atmosphere of 200 ° C. or higher, preferably 10 N / 676 mm ² or lower. Since the peel strength is low in this way, the glass substrate can be peeled after cooling even when the glass substrate is fixed to the glass pedestal.

Therefore, the temperature-sensitive adhesive of this embodiment is, for example, an adhesive for temporarily fixing a glass substrate in a manufacturing process such as a touch panel and an organic EL element including a process of exposing the glass substrate to a high temperature atmosphere of 200 ° C. or higher. It is preferably used as an agent.

Hereinafter, the present invention will be specifically described with reference to examples and comparative examples, but the present invention is not limited to these examples.

(Synthesis Example 1: Synthesis of first side chain crystalline polymer)
The monomers shown in Table 1 were added to the reaction vessel at the ratio shown in Table 1. The monomers shown in Table 1 are as follows.
C22A: Behenyl acrylate C18A: Stearyl acrylate C1A: Methyl acrylate AA: Acrylic acid V3F: Reactive fluorine compound (2,2,2-trifluoroethyl acrylate represented by the above formula (Ia): Osaka Organic Chemical Industry Co., Ltd. "Biscoat 3F")

Next, 200 parts by weight of a solvent was added to the reaction vessel with respect to 100 parts by weight of the monomer mixture. As the solvent, a mixed solvent of ethyl acetate: toluene = 8: 2 (weight ratio) was used. Further, “Perloyl OPP” manufactured by NOF Co., Ltd. was added to the reaction vessel at a ratio of 0.3 part by weight as a polymerization initiator, and then stirred at 55 ° C. for 4 hours to copolymerize these monomers. A side chain crystalline polymer was obtained. The obtained first side chain crystalline polymer had a weight average molecular weight of 600,000 and a melting point of 55 ° C. The weight average molecular weight is a value obtained by measuring by GPC and converting the obtained measurement value into polystyrene. The melting point is a value measured using DSC under measurement conditions of 10 ° C./min.

(Synthesis Example 2: Synthesis of second side chain crystalline polymer)
The monomers shown in Table 1 were added to the reaction vessel at the ratio shown in Table 1. Next, 100 parts by weight of the solvent was added to the reaction vessel with respect to 100 parts by weight of the monomer mixture. Toluene was used as the solvent. Further, 1.0 part by weight of “Perhexyl PV” manufactured by NOF Corporation as a polymerization initiator and 6.0 parts by weight of dodecyl mercaptan as a chain transfer agent were respectively added to the reaction vessel, and then at 60 ° C. for 2 hours. Stir. Then, the mixture was further stirred for 3 hours at the reflux temperature to copolymerize these monomers to obtain a second side chain crystalline polymer. The weight average molecular weight of the obtained second side chain crystalline polymer was 8000, and the melting point was 51 ° C.

Example 1
For 100 parts by weight of the first side chain crystalline polymer obtained in Synthesis Example 1, 1 part by weight of the second side chain crystalline polymer obtained in Synthesis Example 2 and aluminum trisacetylacetonate ( Kawaken Fine Chemical Co., Ltd.) was mixed at a ratio of 10 parts by weight. Subsequently, ethyl acetate was added to the obtained mixture so that solid content might be 30 weight%, and the coating liquid was prepared.

The obtained coating solution was applied onto a release film and heated at 100 ° C. for 10 minutes to carry out a crosslinking reaction. In this way, a temperature-sensitive adhesive sheet having a thickness of 25 μm was obtained. As the release film, a polyethylene terephthalate film having a thickness of 50 μm and having a surface coated with silicone was used.

(Examples 2 to 7 and Comparative Example 1)
A coating solution was prepared in the same procedure as in Example 1 except that the components shown in Table 2 were used in the proportions shown in Table 2 to obtain a temperature-sensitive adhesive sheet. As a tackifier, “Super Ester A-100” manufactured by Arakawa Chemical Industries, Ltd. having a softening point of 95 to 105 ° C. was used.

<Evaluation>
With respect to the thermosensitive adhesive sheets obtained in Examples 1 to 7 and Comparative Example 1, (1) heat resistance, (2) peelability, and (3) peel strength were evaluated by the following methods. The results are shown in Table 2.

(1) Heat resistance A glass substrate (cover glass (50 mm × 70 mm)) was fixed on a glass pedestal through a temperature-sensitive adhesive sheet in an atmosphere of 50 ° C. Next, the glass pedestal on which the glass substrate was fixed was allowed to stand for 60 minutes in an atmosphere of 200 ° C. Thereafter, the state of the glass substrate was visually observed and evaluated according to the following criteria. In the case of ○, it was judged that the glass substrate was fixed to the glass pedestal even in a high-temperature atmosphere, and was evaluated as a temperature-sensitive adhesive sheet having good heat resistance.
○: When the glass substrate was not lifted.
X: When a float is seen in the glass substrate.

(2) Peelability After visually observing the heat resistance, the glass pedestal on which the glass substrate was fixed was allowed to stand for 5 minutes in a 5 ° C atmosphere. Then, the glass substrate was peeled by hand from the glass pedestal and evaluated according to the following criteria. In the case of (double-circle), (circle), or (triangle | delta), it evaluated that it was a temperature-sensitive adhesive sheet which has favorable peelability.
A: When the glass substrate can be easily peeled from the glass pedestal.
○: When the glass substrate can be peeled off from the glass pedestal, although some resistance is felt.
Δ: Resistance is felt, but the glass substrate can be peeled from the glass pedestal.
X: When the glass substrate was broken or the glass substrate could not be peeled from the glass pedestal.

(3) Peel strength As shown in FIG. 1, one slide glass 1 a was fixed to the pedestal 2 out of the two

slide glasses

1 a and 1 b (width 26 mm and length 76 mm). Fixing was performed by holding both ends of the slide glass 1a with the fixture 3. Another slide glass 1b was fixed to the slide glass 1a in a cross shape through a temperature-sensitive adhesive sheet 4 in an atmosphere of 50 ° C. and allowed to stand for 20 minutes. Thereafter, the temperature was raised to 200 ° C. and allowed to stand for 20 minutes. Subsequently, after cooling to 5 degreeC and leaving still for 5 minutes, the slide glass 1b was lifted in 5 degreeC atmosphere, and the peeling strength when the slide glass 1b peeled from the slide glass 1a was measured. The results are shown in the column of “5 ° C. Peel Strength” in Table 2.

As is apparent from Table 2, it can be seen that the temperature-sensitive adhesive sheets of Examples 1 to 7 containing the second side chain crystalline polymer all have good heat resistance and peelability. Furthermore, it can be seen that when exposed to an atmosphere of 5 ° C., the peel strength is low at 10 N / 676 mm ² or less (that is, the adhesive strength is reduced). That is, when the temperature-sensitive adhesive (temperature-sensitive adhesive sheet) of this embodiment is used, the glass substrate can be fixed even in a high temperature atmosphere, and when it is cooled from a high temperature atmosphere and exposed to a low temperature atmosphere. It can also be seen that the fixed glass substrate can be peeled off without problems. On the other hand, Comparative Example 1 not containing the second side chain crystalline polymer was inferior in peelability and could not withstand practical use.

(Example 8)
In Example 6, “Super Ester A-125” (manufactured by Arakawa Chemical Industries, Ltd.) having a softening point of 120 to 130 ° C. was used instead of Super Ester A-100. A coating solution was prepared according to the procedure to obtain a temperature-sensitive adhesive sheet. The peel strength of the obtained sheet was measured by the same procedure as in Example 1. As a result, it was 6.0 N / 676 mm ² .

Therefore, from the measured value of peel strength, when the temperature sensitive adhesive (temperature sensitive adhesive sheet) of this embodiment is used, the glass substrate is fixed when cooled from a high temperature atmosphere and exposed to a low temperature atmosphere. It can be seen that can be peeled off without problems.

(Synthesis Example 3: Synthesis of first side chain crystalline polymer)
The monomers shown in Table 3 were added to the reaction vessel at the ratio shown in Table 3, and the monomers were copolymerized in the same manner as in Synthesis Example 1 to obtain a first side chain crystalline polymer. The obtained first side chain crystalline polymer had a weight average molecular weight of 550000 and a melting point of 25 ° C.

Example 9
A coating solution was prepared in the same procedure as in Example 1 except that the components shown in Table 4 were used in the proportions shown in Table 4 to obtain a temperature-sensitive adhesive sheet. As a tackifier, “Super Ester A-100” manufactured by Arakawa Chemical Industries, Ltd. having a softening point of 95 to 105 ° C. was used.

For the obtained temperature-sensitive adhesive sheet, (1) heat resistance, (2) peelability, and (3) peel strength were evaluated in the same manner as in Example 1. The results are shown in Table 4.

As is clear from Table 4, it can be seen that the temperature-sensitive adhesive sheet of Example 9 has good heat resistance and peelability. Furthermore, it can be seen that when exposed to an atmosphere at 5 ° C., the peel strength is as low as 10 N / 676 mm ² or less (that is, the adhesive strength is reduced).

(Synthesis Examples 4 to 7: Synthesis of second side chain crystalline polymer)
The monomer shown in Table 5 was added to the reaction vessel at the ratio shown in Table 5, and the monomer was copolymerized in the same manner as in Synthesis Example 2 except that the addition amount of the chain transfer agent dodecyl mercaptan was changed to the ratio shown below. A second side chain crystalline polymer was obtained. Table 5 shows the weight average molecular weight and melting point of the obtained second side chain crystalline polymer. For comparison, Table 5 also shows Synthesis Example 2 described above.

(Dodecyl mercaptan addition amount)
Synthesis Example 4: 15.0 parts by weight Synthesis Example 5: 3.0 parts by weight Synthesis Example 6: 0.5 parts by weight Synthesis Example 7: 0.2 parts by weight

(Examples 10 to 13)
A coating solution was prepared in the same procedure as in Example 1 except that the components shown in Table 6 were used in the proportions shown in Table 6 to obtain a temperature-sensitive adhesive sheet. As a tackifier, “Super Ester A-100” manufactured by Arakawa Chemical Industries, Ltd. having a softening point of 95 to 105 ° C. was used.

For the obtained temperature-sensitive adhesive sheet, (1) heat resistance, (2) peelability, and (3) peel strength were evaluated in the same manner as in Example 1. The results are shown in Table 6. For comparison, Table 6 also shows Example 6 described above.

As is apparent from Tables 5 and 6, it can be seen that the second side chain crystalline polymer has particularly good peelability when it has a weight average molecular weight of 4000 to 40000.

Claims

A temperature-sensitive pressure-sensitive adhesive containing a first side chain crystalline polymer, the adhesive strength of which decreases at a temperature lower than the melting point of the first side chain crystalline polymer;
The temperature sensitive adhesive which further contains the 2nd side chain crystalline polymer which has a weight average molecular weight smaller than the said 1st side chain crystalline polymer.
The temperature-sensitive adhesive according to claim 1, further comprising a tackifier.
The temperature-sensitive adhesive according to claim 2, wherein the tackifier has a softening point of 90 to 110 ° C.
The temperature-sensitive adhesive according to claim 2 or 3, wherein the content of the tackifier is 15 to 35 parts by weight with respect to 100 parts by weight of the first side chain crystalline polymer.
The temperature-sensitive adhesive according to any one of claims 1 to 4, wherein the first side-chain crystalline polymer has a weight average molecular weight greater than 100,000.
The temperature-sensitive adhesive according to any one of claims 1 to 5, wherein the second side chain crystalline polymer has a weight average molecular weight of 100,000 or less.
The temperature-sensitive adhesive according to any one of claims 1 to 6, wherein the second side chain crystalline polymer has a weight average molecular weight of 4000 to 100,000.
The temperature-sensitive adhesive according to any one of claims 1 to 7, wherein the content of the second side chain crystalline polymer is 1 to 20 parts by weight with respect to 100 parts by weight of the first side chain crystalline polymer. .
The first side chain crystalline polymer and the second side chain crystalline polymer have a (meth) acrylate having a linear alkyl group having 16 or more carbon atoms, and a (meth) acrylate having an alkyl group having 1 to 6 carbon atoms. The temperature-sensitive adhesive according to any one of claims 1 to 8, which is a copolymer obtained by polymerizing a polar monomer.
The temperature-sensitive adhesive according to claim 9, wherein the first side chain crystalline polymer is a copolymer obtained by further polymerizing a reactive fluorine compound.
The temperature-sensitive adhesive according to any one of claims 1 to 10, wherein the glass-glass peel strength at 5 ° C after exposure to a high temperature atmosphere of 200 ° C or higher is 10 N / 676 mm 2 or less.
The temperature-sensitive adhesive according to any one of claims 1 to 11, which is used for temporarily fixing a glass substrate.
A temperature-sensitive adhesive sheet comprising the temperature-sensitive adhesive according to any one of claims 1 to 12.
A temperature-sensitive adhesive tape comprising a film-like or sheet-like substrate and an adhesive layer comprising the temperature-sensitive adhesive according to any one of claims 1 to 12 laminated on at least one surface of the substrate. .