JP2019119872A - Polyester-based adhesive composition, polyester-based adhesive, adhesive film, adhesive composition for heat resistant adhesive film, heat resistant adhesive film for masking, and use method of heat resistant adhesive film for masking - Google Patents

Abstract

To provide a polyester adhesive composition less in secular change such as increase of adhesive force even in use under high temperature environment, a polyester-based adhesive, an adhesive film, an adhesive composition for heat resistant adhesive film, a heat resistant adhesive film for masking, and a use method of the heat resistant adhesive film for masking.SOLUTION: A polyester-based adhesive composition contains a polyester resin having a carboxyl group derived from at least one of tri- or higher valent carboxylic acid and acid anhydride thereof in at least one of a side chain or a terminal of a molecule.SELECTED DRAWING: None

Description

  The present invention relates to a polyester-based pressure-sensitive adhesive composition, a polyester-based pressure-sensitive adhesive, a pressure-sensitive adhesive film, a pressure-sensitive adhesive composition for a heat-resistant pressure-sensitive adhesive film, a heat-resistant pressure-sensitive adhesive film for masking, and a method for using a heat-resistant pressure-sensitive adhesive film for masking. Even when used in a high temperature environment in a state of being attached to the body, when the adhesive is peeled off from the adherend, contamination such as the adhesive remaining on the adherend is less likely to occur, and the change in adhesive strength with time The present invention relates to a heat resistant adhesive film for masking, a polyester based adhesive composition used therefor, a polyester based adhesive, an adhesive film, an adhesive composition for a heat resistant adhesive film, and a method for using the heat resistant adhesive film for masking.

  Heretofore, it has been known that polyester resins having excellent chemical resistance, mechanical strength and the like can be obtained by combining a polyvalent carboxylic acid component and a polyol component, and are also useful in the field of pressure-sensitive adhesives . As such an adhesive, the thing of patent documents 1-3 is mentioned, for example. According to Patent Document 1, the weight-average molecular weight of the main component polyester-based resin is relatively small, and the viscosity at 23 ° C. is suppressed to a predetermined value or less, so that dilution with an organic solvent is not necessary. It is said that good coatability is realized in the temperature range of

  Moreover, the thing of patent document 2 uses less than half aromatic dicarboxylic acid with respect to the whole carboxylic acid component as a carboxylic acid component, and uses the glycol which has a hydrocarbon in a side chain as a polyhydric alcohol component, and is an adhesive property. It is said that a pressure-sensitive adhesive which is excellent in heat resistance and mechanical strength can be obtained.

  And the thing of the patent document 3 makes polyester polymer which contains a polyhydric carboxylic acid component and a glycol component as a principal chain, and polyester co-ester in which the compound which has one carboxy group and one acid anhydride group was introduce | transduced at the terminal By using a polymer, it is said that the polymer has a preferable range of molecular weight and high acid value, and as a result, while suppressing gelation, adhesion and adhesion which are contradictory characteristics are simultaneously improved.

International Publication No. 2011/081163 Japanese Patent Application Publication No. 2007-45914 JP, 2013-75965, A

  However, although the thing of the said patent document 1 can implement | achieve favorable coating property in the temperature range around room temperature, since the cohesion force is low, the handleability was very bad and was not able to endure practical use. In particular, since there is no stiffness immediately after coating, it is also weak to dents, and the yield at the time of producing the adhesive also deteriorates. Further, in applications where heat resistance is required, there is a problem that the adhesive strength is excessively increased, and when used as a heat-resistant adhesive film for masking, contamination occurs such that the adhesive remains on the adherend. Moreover, although the thing of the said patent document 2 is excellent in the adhesion physical property and an adhesive excellent in heat resistance and mechanical strength is obtained, when using as a masking film of the surface protection use of a to-be-adhered body, under high temperature environment There is room to further improve the removability after being used in And although the thing of the said patent document 3 is improving an adhesive property and adhesiveness which are the characteristics contrary to this, suppressing gelation simultaneously, this thing is an adhesive agent and it peels. It is not suitable as a masking film for the surface protection use of a to-be-adhered body, since it is not an adhesive which presupposes.

  In the present invention, under such background, a polyester-based pressure-sensitive adhesive composition having a small change with time such as increase in adhesion even if used under high temperature environment, polyester-based pressure-sensitive adhesive, pressure-sensitive adhesive film, heat-resistant pressure-sensitive adhesive film It is an object of the present invention to provide a method of using a pressure-sensitive adhesive composition, a heat-resistant adhesive film for masking, and a heat-resistant adhesive film for masking.

However, the present inventor has made the polyester system in which a carboxy group derived from at least one of a trivalent or higher carboxylic acid and an acid anhydride thereof is positively contained in at least one of the side chain and the end of the polyester resin molecule. By using a resin, it has been found that it is possible to obtain a polyester-based pressure-sensitive adhesive composition capable of suppressing an increase in adhesion even when exposed to a high temperature environment, and the first invention has been completed.
In addition, the inventor of the present invention can suppress the increase in adhesion even when exposed to a high temperature environment by using a polyester resin having a product of the acid value and the weight average molecular weight equal to or more than a specific value. The inventors have found that a pressure-sensitive adhesive composition can be obtained, and completed the second invention.

  That is, the present invention provides a polyester-based pressure-sensitive adhesive composition containing a polyester-based resin having a carboxy group derived from at least one of a trivalent or higher carboxylic acid and an acid anhydride thereof in at least one of side chain and terminal of molecule. As the first summary.

  The second aspect of the present invention is a polyester-based pressure-sensitive adhesive composition containing a polyester-based resin having a product of an acid value (mg KOH / g) and a weight average molecular weight of 350,000 or more.

  And this invention makes the polyester-based adhesive which the said polyester-based adhesive composition is bridge | crosslinked the 3rd summary, makes the adhesive film which has the adhesive layer containing the said polyester-based adhesive the 4th summary. A fifth aspect of the present invention is a pressure-sensitive adhesive composition for a heat-resistant pressure-sensitive adhesive film, which comprises the polyester-based pressure-sensitive adhesive composition. The heat-resistant adhesive film for masking having the pressure-sensitive adhesive layer for heat-resistant adhesive film comprising the pressure-sensitive adhesive composition for heat-resistant adhesive film is the sixth aspect, and the heat-resistant adhesive film for masking is the pressure-sensitive adhesive layer for the heat-resistant adhesive film. The process of affixing to an adherend using adhesive force, the heating process of heating the heat-resistant adhesive film for masking attached to the above-mentioned adherend together with the above-mentioned adherend to 120 ° C. or higher, and the heating process A seventh aspect of the present invention is a method of using the heat-resistant adhesive film for masking, comprising the step of peeling the heat-resistant adhesive film for masking from the adherend.

  The eighth aspect of the present invention is a polyester-based pressure-sensitive adhesive composition containing a polyester-based resin having an acid value of 5 mg KOH / g or more and a weight-average molecular weight of 2,000 or more, an epoxy-based crosslinking agent and an alcohol solvent. It is said that.

In general, in the production of polyester resins, the terminal of the molecule is often made to be a hydroxyl group, and in many cases, no acidic group such as a carboxy group is left. This is because hydrolysis of the polyester resin is promoted if the acid group remains. Therefore, particularly for adhesive applications where environmental durability is required, designs have been carried out in which no acid group is left as much as possible.
However, in the first aspect of the invention, sufficient crosslink density is achieved by making the acid group a carboxy group, which is an acid group, positively at the terminal end of the molecule or in the side chain in the molecule. It has been found that it is possible to obtain a polyester-based pressure-sensitive adhesive composition which can suppress the increase in adhesion and difficulty in peeling even when exposed to a high temperature environment.
In the second invention, paying attention to the relationship between the acid value and the weight average molecular weight of the polyester resin, the product of the acid value and the weight average molecular weight is used using a polyester resin having a high acid value and a large weight average molecular weight. It has been found that a polyester-based pressure-sensitive adhesive composition can be obtained which can suppress the increase in adhesion and difficulty in peeling even when exposed to a high-temperature environment when .

The polyester-based pressure-sensitive adhesive composition of the first invention contains a polyester-based resin having a carboxy group derived from at least one of a trivalent or higher carboxylic acid and an acid anhydride thereof in at least one of the side chain and the end of the molecule. It is a thing.
The polyester-based pressure-sensitive adhesive composition of the second invention contains a polyester-based resin having a product of an acid value (mg KOH / g) and a weight average molecular weight of 350,000 or more.
Therefore, as described above, the increase in adhesion is suppressed even when exposed to a high temperature environment, and the change in adhesion with time can be suppressed.
Therefore, the polyester-based pressure-sensitive adhesive in which the polyester-based pressure-sensitive adhesive composition of the present invention is crosslinked is less likely to cause contamination such as the pressure-sensitive adhesive remaining on the adherend, even when used under high temperature environment It is suitably used for the pressure-sensitive adhesive layer of the heat-resistant adhesive film for masking with little change in adhesion with time.

  Hereinafter, although the configuration of the present invention will be described in detail, these are merely examples of the preferred embodiments.

The polyester-based pressure-sensitive adhesive composition of the first invention (hereinafter, the polyester-based pressure-sensitive adhesive composition may be abbreviated as “pressure-sensitive adhesive composition”) has at least one of a side chain and an end of the molecule, a trivalent or higher carboxylic acid. It is characterized by containing polyester-based resin which has a carboxy group derived from at least one of an acid and its acid anhydride.
The pressure-sensitive adhesive composition according to the second aspect of the invention is characterized in that it contains a polyester resin having a product of an acid value (mg KOH / g) and a weight average molecular weight of 350,000 or more.
The components constituting such a polyester-based pressure-sensitive adhesive composition of the present invention will be sequentially described below.

<Polyester resin>
The polyester-based resin used in the present invention is obtained by copolymerizing a copolymer component containing a polyvalent carboxylic acid and an acid anhydride thereof (hereinafter sometimes abbreviated as "carboxylic acids") and a polyol.
In general polyester resins, divalent carboxylic acids are generally used as polyvalent carboxylic acids, but in the first invention, trivalent or higher carboxylic acids are used in addition to divalent carboxylic acids. Thus, at least one of the side chain and the end of the polyester-based resin molecule is characterized by having a carboxy group derived from the trivalent or higher carboxylic acid.
The second invention is characterized in that the product of the acid value of the polyester resin and the weight average molecular weight is not less than a specific value, that is, the acid value is high and the weight average molecular weight is large.

[Polyvalent carboxylic acids]
Examples of divalent carboxylic acids used as constituent materials of polyester resins include malonic acids, dimethylmalonic acids, succinic acids, glutaric acids, adipic acids, trimethyladipic acids, pimelic acids, 2, 2-dimethyl glutaric acids, Aliphatic dicarboxylic acids such as azelaic acids, sebacic acids, decanedicarboxylic acids, fumaric acids, maleic acids, itaconic acids, thiodipropionic acids, diglycolic acids, 1,9-nonane dicarboxylic acids, etc .;
Phthalic acids, terephthalic acids, isophthalic acids, benzyl malonic acids, diphenic acids, 4,4'-oxydibenzoic acids, further 1,8-naphthalene dicarboxylic acids, 2,3
-Aromatic dicarboxylic acids such as naphthalene dicarboxylic acids such as naphthalene dicarboxylic acids and 2,7-naphthalene dicarboxylic acids;
Alicyclic groups such as 1,3-cyclopentane dicarboxylic acids, 1,2-cyclohexane dicarboxylic acids, 1,3-cyclopentane dicarboxylic acids, 1,4-cyclohexane dicarboxylic acids, 2,5-norbornane dicarboxylic acids, adamantane dicarboxylic acids and the like Dicarboxylic acids; and the like.
These divalent carboxylic acids can be used alone or in combination of two or more.

  Moreover, as a carboxylic acid more than trivalence used as a constituent raw material of polyester-based resin, trimellitic acid, pyromellitic acid, adamantane tricarboxylic acid, trimesic acid etc. are mentioned, for example. Among these, dianhydrides of tetracarboxylic acids such as pyromellitic dianhydride are preferably used in view of high molecular weight and high acid value. Further, pyromellitic dianhydride is more preferable in terms of versatility. These trivalent or higher carboxylic acids can be used alone or in combination of two or more.

  As content of the said trivalent or more carboxylic acids, it is trivalent or more carboxylic acids / divalent carboxylic acid = 1 / 99-40 / 60 as a content ratio (molar ratio) with respect to the said bivalent carboxylic acids It is preferably, particularly preferably 5/95 to 30/70, more preferably 10/90 to 20/80. When the content ratio (molar ratio) of the trivalent or higher carboxylic acid to the divalent carboxylic acid is in the above range, an appropriate amount of acid value is imparted while maintaining the glass transition temperature low, and the molecular weight is controlled. It is preferable in terms of ease of operation.

  Further, in the present invention, among the above-mentioned divalent carboxylic acids, from the viewpoint of imparting tackiness, aliphatic dicarboxylic acids are preferably contained, and specifically, for example, sebacic acids are preferable.

  The content ratio of such aliphatic dicarboxylic acids is preferably 5 mol% or more, particularly preferably 50 to 99 mol%, still more preferably 70 to 95 mol%, based on the whole polybasic carboxylic acids. When the content ratio is too small, the glass transition point of the resin tends to be higher than necessary, and the adhesion performance tends to be lowered. If the amount is too large, crystallinity tends to be obtained and the solution stability of the pressure-sensitive adhesive tends to be reduced.

  Further, among the above-mentioned divalent carboxylic acids, it is also preferable to include an aromatic dicarboxylic acid from the viewpoint of imparting cohesive power, and specifically, for example, isophthalic acids are preferably used.

  The content ratio of such aromatic dicarboxylic acids is preferably 1 mol% or more, particularly preferably 2 to 50 mol%, and still more preferably 3 to 30 mol% with respect to the entire polyvalent carboxylic acids. If the content ratio is too low, crystallization tends to occur and the solution stability of the pressure-sensitive adhesive tends to decrease. When the amount is too large, the glass transition temperature tends to be high and the adhesion performance tends to be lowered.

  In the present invention, it is also preferable to use an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid in combination as the polyvalent carboxylic acid from the viewpoint of the adhesive property. The content ratio (molar ratio) of the aromatic dicarboxylic acids and the aliphatic dicarboxylic acids is preferably aromatic dicarboxylic acids / aliphatic dicarboxylic acids = 1/99 to 49/51, particularly preferably 5/95 to 30 / 70. It is preferable in the point which is easy to balance the glass transition temperature and cohesive force as it is in the range of this content ratio.

[Polyol]
As said polyol used as a constituent raw material of polyester-type resin, the aliphatic diol of a linear structure, other dihydric alcohol, polyhydric alcohol more than trivalence etc. are mentioned, for example.
Examples of aliphatic diols having a linear structure include ethylene glycol, diethylene glycol, triethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and the like. , 9-nonanediol, 1, 10-decanediol, 1, 12-dodecanediol, polyethylene glycol, polytetramethylene glycol and the like.
As other dihydric alcohols, for example, propylene glycol, dipropylene glycol, 2,4-dimethyl-2-ethylhexane-1,3-diol, 2-methyl-1,3-propanediol, 2,2-dimethyl 1,3-propanediol (neopentyl glycol), 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 1,3-butanediol, Aliphatic diols having a branched structure such as 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,6-hexanediol;
1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, spiroglycol, tricyclodecanedimethanol, adamantanediol, 2,2,4,4-tetramethyl-1,3 -Alicyclic diols such as cyclobutanediol;
4,4'-thiodiphenol, 4,4'-methylenediphenol, bisphenol S, bisphenol A, bisphenol fluorene, 4,4'-dihydroxybiphenyl, o-, m- and p-dihydroxybenzene, 2, 5- Aromatic diols such as naphthalenediol and p-xylenediol; and ethylene oxide and propylene oxide adducts thereof; and the like.
Examples of trihydric or higher polyhydric alcohols include pentaerythritol, dipentaerythritol, tripentaerythritol, glycerin, trimethylolpropane, trimethylolethane, 1,3,6-hexanetriol, adamantantriol and the like.

  Among these, it is preferable to use a polyol having a branched structure in that the crystallinity is broken and the solution stability is improved, and from the viewpoint of versatility, aliphatic diols having a branched structure, especially 2,2- It is preferred to use dimethyl-1,3-propanediol (neopentyl glycol), 2-ethyl-2-isobutyl-1,3-propanediol.

  Furthermore, from the viewpoint of lowering the glass transition temperature (Tg) and increasing the adhesion performance, it is preferable to use an aliphatic diol having a linear structure, and further, except ethylene glycol in that it has flexibility and excellent adhesion performance. Aliphatic diols having a linear structure are preferably used, and in particular, diethylene glycol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol are preferably used, and in particular, crystals of a resin are preferably used. It is preferable to use diethylene glycol and 1,5-pentanediol from the viewpoint of lowering the degree of oxidation and being more excellent in adhesion.

  The aliphatic diol having a branched structure is preferably 10 to 100 mol%, particularly 20 to 95 mol%, more preferably 30 to 90 mol%, particularly preferably 51 to 85 mol%, based on the whole polyol component. .

  The aliphatic diol having a linear structure is preferably 0 to 90 mol%, particularly 5 to 80 mol%, further 10 to 70 mol%, particularly 15 to 49 mol%, relative to the whole polyol component. .

  The amount of the other diol other than the above is preferably 50% by mole or less, particularly preferably 30% by mole or less, and further preferably 10% by mole or less.

  In the present invention, from the viewpoint of heat resistance, the content of the compound containing an ether bond is preferably 50% by weight or less, particularly preferably 20% by weight or less, and further preferably 10% by weight or less in the polyester resin. In particular, 5% by weight or less is preferable.

  The compounding ratio of the polyvalent carboxylic acids (including trivalent or higher carboxylic acids) and the polyol is preferably 1 to 3 equivalents of the polyol per 1 equivalent of the polyvalent carboxylic acids, particularly preferably 1.1. ~ 2 equivalents. If the blending ratio of the polyol is too low, there is a tendency that it is difficult to achieve high molecular weight, and if it is too high, the yield tends to decrease.

[Production of polyester resin]
In general, polyester resins can be produced by selecting polyvalent carboxylic acids and polyols arbitrarily and subjecting them to a polycondensation reaction by a known method in the presence of a catalyst. After the reaction has been carried out, a polycondensation reaction is carried out.
The polyester-based resin used in the present invention can also be produced by a method according to this.
The polyester-based resin used in the first invention is a resin having a carboxy group derived from at least one of a trivalent or higher carboxylic acid and an acid anhydride thereof on at least one of the side chain and the end of the molecule. Also in the invention, it is preferable to use such a polyester resin.
The polyester-based resin having the above-mentioned characteristics is, for example, a hydroxyl group-containing prepolymer having a repeating unit of about 1 to 10, which is obtained by subjecting a divalent carboxylic acid and a polyol to an esterification reaction. It can be produced by a method of chain extension with an acid anhydride of a trivalent or higher carboxylic acid such as an anhydride.

  That is, first, a predetermined amount of a divalent carboxylic acid and a polyol are mixed without solvent, this mixture is charged in a reaction can, and usually heated to 170 to 260 ° C. to produce by-product water or The esterification reaction or transesterification reaction is allowed to proceed while removing methanol to obtain a hydroxyl group-containing prepolymer. The mixing ratio (molar ratio) of the divalent carboxylic acid to the polyol is preferably 1.05 to 1.65 moles of the polyol, and more preferably 1.08 to 1 mole of the divalent carboxylic acid. It is preferable to set it as -1.5 mol, especially 1.1-1.3 mol.

  In the above reaction, an esterification catalyst, a transesterification catalyst, other polymerization catalysts and the like can be appropriately blended. Specifically, for example, titanium-based catalysts such as tetraisopropyl titanate and tetrabutyl titanate, antimony trioxide and the like And the catalysts such as zinc acetate, manganese acetate, dibutyltin oxide and the like, and these can be used singly or in combination of two or more. Among these, antimony trioxide, tetrabutyl titanate, germanium dioxide and zinc acetate are preferable in terms of the balance between the height of catalytic activity and the hue of the resulting reactant.

  The compounding amount of the catalyst is preferably 1 to 10,000 ppm, particularly preferably 10 to 5,000 ppm, still more preferably 20 to 3,000 ppm, based on the total amount of the copolymer components (based on weight). If the amount is too small, the reaction tends to be difficult to proceed sufficiently. If the amount is too large, there is no advantage such as shortening of the reaction time, and side reactions tend to occur.

  Next, a polyester-based resin can be obtained by chain extension of the obtained hydroxyl group-containing prepolymer by a ring-opening addition reaction using a trivalent or higher carboxylic acid and its acid anhydride.

  The chain extension of the above hydroxyl group-containing prepolymer with a trivalent or higher carboxylic acid and its acid anhydride is usually carried out at 230 ° C. or less, preferably 60 to 210 ° C., particularly preferably 150 to 200 It is made to react at ° C. If the reaction temperature is too low, the reaction tends not to proceed sufficiently, and if it is too high, side reactions such as decomposition tend to occur. Moreover, the pressure at the time of reaction is usually normal pressure. And, the time taken for the reaction is usually 0.5 to 10 hours.

  When a trivalent carboxylic acid and an acid anhydride thereof are used to carry out the above chain extension reaction, a carboxy group derived from a trivalent or higher carboxylic acid is easily introduced at the molecular terminal, and a tetravalent carboxylic acid and a carboxylic acid When the acid anhydride is used, it becomes easy to introduce | transduce the carboxy group derived from the trivalent or more carboxylic acid in a molecule | numerator side chain and the terminal.

  In addition, after the hydroxyl group-containing prepolymer is produced, a polycondensation reaction may be performed in the same manner as a general polyester resin, and then the above-mentioned chain extension reaction may be performed. Furthermore, they may be depolymerized using a compound containing a trivalent or higher carboxylic acid and its acid anhydride to introduce a carboxy group in the side chain and / or the end.

A solvent may not necessarily be used in the above reaction, but if the viscosity of the reaction product is too high, etc., a suitable solvent may be used to facilitate stirring.
Examples of the solvent include ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone, aromatic solvents such as benzene, toluene, xylene, mesitylene and pseudocumene, and amide solvents such as dimethylformamide and dimethylacetamide. . However, it is preferable not to use solvents that may react with polyester resins, such as ester solvents and alcohol solvents.

  As the reaction conditions for carrying out the polycondensation reaction, the same amount of catalyst as used in the above esterification reaction is further blended in the same amount, and the reaction temperature is preferably 220 to 280 ° C., particularly preferably 230 to 270 ° C. Preferably, the reaction system is gradually depressurized and finally reacted at 5 hPa or less. If the reaction temperature is too low, the reaction tends not to proceed sufficiently, and if it is too high, side reactions such as decomposition tend to occur. Also, the time taken for the reaction is usually 0.5 to 10 hours. The catalyst used in the chain extension reaction (polycondensation reaction) may be added after completion of the esterification reaction, but may be added in advance before the esterification reaction.

  In addition to the above method, for example, an anhydride of a trivalent or higher carboxylic acid is added to the terminal hydroxyl group of the polyester or the oligomer obtained by the esterification reaction, and the polyester resin is It can also be obtained by replacing with a plurality of carboxy groups. Furthermore, it can also be obtained by producing a polyester, depolymerizing it using a trivalent or higher carboxylic acid, and adding a plurality of carboxy groups to the ends of the molecule. These methods may be performed alone or in combination. When performing two or more, it may carry out simultaneously and may carry out by providing a time difference.

The polyester resin thus obtained preferably has an acid value of 5 mg KOH / g or more, more preferably 10 to 180 mg KOH / g, and still more preferably 20 to 150 mg KOH / g. And, among them, 30 to 120 mg KOH / g is more preferable, 40 to 100 mg KOH / g is even more preferable, and 50 to 80 mg KOH / g is particularly preferable. If the acid value is too low, adhesion tends to be reduced and the effects of the present invention can not be sufficiently obtained. In addition, when an acid value is too high, there exists a tendency for water resistance to fall.
The acid value of the polyester-based resin is determined by neutralization titration based on JIS K 0070.

In addition, the acid value in this invention means content of the carboxy group in polyester-type resin. The carboxy group also includes a carboxylate ion state in which the carboxy group is neutralized by a basic compound.
The adjustment of the acid value can be performed, for example, according to the amount of trivalent or higher carboxylic acid and its acid anhydride, reaction conditions (reaction time of chain extension reaction), and the like.

  The weight average molecular weight of the polyester resin is preferably 2,000 to 500,000, more preferably 5,000 to 200,000, and particularly preferably 10,000 to 100,000. If the weight average molecular weight is too large, the handling tends to be reduced and the economy tends to be reduced due to the need to use a large amount of dilution solvent. On the other hand, when the weight average molecular weight is too small, heat resistance, adhesive strength after heat resistance, and adhesive residue after peeling tend to be deteriorated.

The above-mentioned weight average molecular weight is a weight average molecular weight by standard polystyrene molecular weight conversion, and high-performance liquid chromatograph (Tosoh Corp. make "HLC-8320GPC"), column: TSKgel SuperMultipore HZ-M (exclusion limit molecular weight: 2 × 10) ⁶ , the number of theoretical plates: 16,000, per filler, filler material: styrene-divinylbenzene copolymer, filler particle diameter: 4 .mu.m).

It is important that the product of the acid value and the weight average molecular weight of the polyester resin used in the second invention is 350,000 or more. That is, by using a polyester resin having a high acid value of the polyester resin and a large weight average molecular weight, it is possible to impart cohesion when used as a pressure sensitive adhesive and to suppress an increase in the adhesive strength even when exposed to a high temperature environment. It is possible to suppress the change in adhesion with time. The preferable range of this product is 450,000 to 10,000,000, and the particularly preferable range is 1,000,000 to 7,000,000.
In addition, since a general polyester resin has a carboxy group only at the molecular terminal, the acid value is low, and it is difficult to achieve 350,000 or more by the product of the acid value and the weight average molecular weight.
As described above, in order to obtain a polyester resin having a product of an acid value and a weight average molecular weight of 350,000 or more, at least one of a side chain and an end of the molecule is a trivalent or higher carboxylic acid and its acid anhydride It is preferable to have a carboxy group derived from at least one.

  The glass transition temperature (Tg) of the polyester-based resin is preferably -90 to 20 ° C, particularly preferably -80 to 0 ° C, and still more preferably -60 to -20 ° C. If the glass transition temperature (Tg) is too high, the adhesion of the resulting pressure-sensitive adhesive composition tends to be reduced. On the other hand, when the glass transition temperature (Tg) is too low, the heat resistance tends to decrease and the cohesion tends to decrease.

The glass transition temperature (Tg) is a differential scanning calorimeter DSC made by TA Instruments.
It is measured using Q20. The measurement temperature range is −90 ° C. to 100 ° C., and the temperature increase rate is 10 ° C./min.

  It is preferable from the viewpoint of storage stability that the above-mentioned polyester resin is not crystallized, but even when it is crystallized, it is preferable that the crystallization energy of the polyester resin is as low as possible, usually 35 J / g or less, preferably 20 J / G or less, particularly preferably 10 J / g or less, particularly preferably 5 J / g or less.

  In the pressure-sensitive adhesive composition of the present invention, optional components may be used together with the above-mentioned polyester resin, and as such optional components, for example, a crosslinking agent can be mentioned. The crosslinking agent crosslinks the polyester resin to make it excellent in cohesion, and improves the performance as an adhesive.

<Crosslinking agent>
The crosslinker may be a compound containing a functional group having reactivity with a functional group contained in the polyester resin, for example, a compound containing a functional group having reactivity with a carboxy group in the polyester resin Is used.
As such a crosslinking agent, for example, an epoxy type crosslinking agent, an oxazoline type crosslinking agent, an aziridine type crosslinking agent, a melamine type crosslinking agent, an isocyanate type crosslinking agent, a carbodiimide type crosslinking agent, an amino type crosslinking agent, a metal type crosslinking agent, etc. Can be mentioned.

As said epoxy type crosslinking agent, For example, bisphenol A * epichlorohydrin type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether, 1, 6- hexanediol diglycidyl ether , Trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl erythritol, diglycerol polyglycidyl ether, 1,3'-bis (N, N-diglycidylaminomethyl) cyclohexane, N , N, N ', N'-tetraglycidyl-m-xylene diamine and the like, and "Tetrad C" manufactured by Mitsubishi Gas Chemical Co., Ltd., Mitsubishi Gas Chemical Co., Ltd. "Tetrad X", Synasia Co. "S-610", such as may be used commercially available products.
Among them, 1,3'-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N ', N'-tetraglycidyl-- in that the increase in adhesion after heating is small and the heat-resistant staining resistance is good. m-xylene diamine is preferred.

  Examples of the oxazoline-based crosslinking agent include, for example, 2,2′-bis (2-oxazoline), 1,2-bis (2-oxazolin-2-yl) ethane, and 1,4-bis (2-oxazoline-2-). Yl) butane, 1,8-bis (2-oxazolin-2-yl) butane, 1,4-bis (2-oxazolin-2-yl) cyclohexane, 1,2-bis (2-oxazolin-2-yl) Aliphatic or aromatic bisoxazoline compounds such as benzene, 1,3-bis (2-oxazoline-2-yl) benzene, 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5 Addition-polymerizable oxazoline ethyl-2-oxazoline, and the like.

  Examples of the aziridine type crosslinking agent include tetramethylolmethane-tri-β-aziridinyl propionate, trimethylolpropane-tri-β-aziridinyl propionate, and N, N′-diphenylmethane-4,4. Examples include '-bis (1-aziridine carboxamide), N, N'-hexamethylene-1,6-bis (1-aziridine carboxamide) and the like.

  Examples of the melamine-based crosslinking agent include hexamethoxymethylmelamine, hexaethoxymethylmelamine, hexapropoxymethylmelamine, hexabutoxymethylmelamine, hexapentyloxymethylmelamine, hexahexyloxymethylmelamine, melamine resins and the like.

Examples of the isocyanate-based crosslinking agent include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hydrogenated tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, hexamethylene Diisocyanate, diphenylmethane-4,4-diisocyanate, isophorone diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, tetramethyl xylylene diisocyanate, 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate, and polyisocyanate compounds thereof And adducts of these with a polyol compound such as trimethylolpropane and the like, burettes and isocyanurates of these polyisocyanate compounds, and the like.
Among them, isocyanurate of hexamethylene diisocyanate and adduct of 2,4-tolylene diisocyanate and / or 2,6-tolylene diisocyanate with trimethylolpropane in view of heat resistance, 2,4-tolylene diisocyanate and And / or isocyanurate of 2,6-tolylene diisocyanate, and an adduct of tetramethyl xylylene diisocyanate and trimethylolpropane are preferable.

  The carbodiimide type crosslinking agent may be a carbodiimide group as a functional group or a compound having at least two or more cyanamide groups in the molecule having a tautomeric relationship, for example, “Carbodilite V” manufactured by Nisshinbo Chemical Co., Ltd. -02 "," Carbodilight V-02-L2 "," Carbodilight SV-02 "," Carbodilight V-04 "," Carbodilight V-10 "," Carbodilight E-03A "," Carbodilight E-02 "," Carbodilight E-04 "and the like. Among them, those having an aromatic group such as a xylylene skeleton, a tolylene skeleton, a diphenylmethane skeleton, a tetramethyl xylylene skeleton and the like are preferable from the viewpoint of the adhesion between the pressure-sensitive adhesive layer and the base material. "Carbodilite E-04" and the like are preferred.

  As an amino type crosslinking agent, hexamethylene diamine, a triethanolamine, etc. are mentioned, for example.

  Examples of metal crosslinking agents include metal alkoxides such as tetraethyl titanate, tetraethyl zirconate, aluminum isopropionate, aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, zirconium, etc. Acetylacetone and acetoacetic acid esters of polyvalent metals, metal chelate compounds of ethylenediaminetetraacetic acid coordination compounds, etc., acetic acid-ammonium complex salt, ammonium-carbonate complex salt and the like can be mentioned.

  As a crosslinking agent, only 1 type chosen from these may be used, and 2 or more types may be used together.

  In the present invention, it is preferable to use an epoxy-based crosslinking agent as the crosslinking agent from the viewpoint of heat resistance of the pressure-sensitive adhesive film and the small amount of adhesive residue after peeling after heat resistance.

The content of the crosslinking agent can be appropriately selected according to the amount of functional groups contained in the polyester resin, the molecular weight of the polyester resin, and the purpose of use, but preferably 2.5 to 5 parts by weight based on 100 parts by weight of the polyester resin It is 30 parts by weight, particularly preferably 5 to 20 parts by weight, and further preferably 7 to 15 parts by weight.
When the amount of the crosslinking agent is too large, crosslinking does not occur to the contrary, adhesion between the pressure-sensitive adhesive layer and the base material and water resistance tend to decrease, and when it is too small, crosslinking tends to be insufficient and adhesion and water resistance tend to decrease.

  The molar ratio of the amount of functional group (carboxy group) in the polyester resin to the amount of functional group in the crosslinking agent is preferably 100/1 to 100/600 as polyester resin / crosslinking agent, and 100/1. 20 to 100/200 is more preferable, 100/40 to 100/150 is further preferable, and 100/60 to 100/110 is particularly preferable. When the amount of functional groups of the crosslinking agent is too large, crosslinking does not occur reversely, adhesion between the pressure-sensitive adhesive layer and the base material, water resistance tends to decrease, and when too small, crosslinking becomes insufficient, heat resistance, resistance after heat resistance peeling There is a tendency for adhesive retention to decrease.

  In the reaction of the polyester resin and the crosslinking agent, an organic solvent having no functional group reactive with these components, for example, esters such as ethyl acetate and butyl acetate, ketones such as methyl ethyl ketone and methyl isobutyl ketone, toluene Organic solvents such as aromatics such as xylene, alcohols such as methanol, ethanol, 1-propanol, 2-propanol, butanol and the like can be used. These can be used alone or in combination of two or more.

In the present invention, among the above organic solvents, in order to extend the pot life when compounding a polyester resin and a liquid containing a crosslinking agent, an alcohol solvent is preferably contained, and in particular, 2-propanol is contained. Is preferred.
Here, the organic solvent is preferably a mixed solvent containing an alcohol-based solvent, and the content ratio of the alcohol-based solvent is preferably 10 to 80% by weight, particularly 20 to 70% by weight in the organic solvent. Further, 30 to 60% by weight is preferable.

In general, when a polyester resin having a high acid value and a large weight average molecular weight and an epoxy crosslinking agent are contained, the pot life tends to be short, but in the present invention, the polyester resin and the epoxy crosslinking are used. The pot life can be extended by containing an alcoholic solvent when forming a solution containing an agent.
That is, the pressure-sensitive adhesive composition of the third invention contains a polyester resin having an acid value of 5 mg KOH / g or more and a weight average molecular weight of 2,000 or more, an epoxy crosslinking agent, and an alcohol solvent.

  In the pressure-sensitive adhesive composition of the present invention, as an optional component, in addition to the above-mentioned crosslinking agent, an antioxidant, a hydrolysis inhibitor, a urethanization catalyst, a catalytic action inhibitor, a softener, insofar as the effects of the present invention are not impaired. Additives such as UV absorbers, stabilizers, antistatic agents, tackifiers, etc., and other additives such as inorganic or organic fillers, powders such as metal powders and pigments, and particles it can. Any of these may be used alone or in combination of two or more.

<Antioxidant>
In the pressure-sensitive adhesive composition of the present invention, by containing the antioxidant, it is possible to suppress the molecular weight decrease of the polyester resin in a heat-resistant environment, and the heat resistance is improved, and the adhesive residue to the adherend It becomes excellent in prevention.
Examples of the antioxidant used in the present invention include hindered phenol-based antioxidants, amine-based antioxidants, sulfur-based antioxidants, phosphoric acid-based antioxidants, and the like. Among them, at least one selected from amine-based antioxidants and phosphoric acid-based antioxidants is preferable, and in particular, antioxidants composed of hindered phenol-based compounds are preferable.
As the hindered phenol-based antioxidant, for example, a hindered group in which a group having a large steric hindrance such as tertiary butyl group is bonded to at least one of adjacent carbon atoms of carbon atoms on the aromatic ring to which a hydroxyl group of phenol is bonded Antioxidants having a phenolic structure can be mentioned.

The content of the antioxidant is preferably 0.01 to 10 parts by weight, more preferably 0.03 to 8 parts by weight, and still more preferably 0.05 to 10 parts by weight with respect to 100 parts by weight of the polyester resin. 5 parts by weight.
When the content is too small, adhesive residue on the adherend tends to be generated, and when the content is too large, the adhesive property tends to be lowered.

  The pressure-sensitive adhesive composition of the present invention may contain, in addition to the above-described additives, a small amount of impurities and the like contained in the raw materials for producing the components of the pressure-sensitive adhesive.

  Further, the polyester-based pressure-sensitive adhesive (hereinafter sometimes abbreviated as "pressure-sensitive adhesive") of the present invention is obtained by crosslinking (curing) the pressure-sensitive adhesive composition of the present invention. The crosslinking (curing) enhances the tackiness of the pressure-sensitive adhesive composition to provide a pressure-sensitive adhesive having a desired tackiness.

  The gel fraction of the pressure-sensitive adhesive is preferably 70% by weight or more, particularly preferably 80 to 99% by weight, and still more preferably 90 to 98% by weight, from the viewpoint of durability and adhesion. If the gel fraction is too low, the cohesion will decrease and the heat resistance tends to decrease. If the gel fraction is too high, there is a concern that the cohesion will be lowered due to an increase in cohesion.

  The gel fraction is a measure of the degree of crosslinking, and is calculated, for example, by the following method. That is, a pressure-sensitive adhesive film (having no separator) formed by forming a pressure-sensitive adhesive layer on a polymer film (for example, a PET film etc.) to be a substrate is wrapped with 200 mesh SUS wire mesh and Soak for 24 hours, and use as a gel fraction the weight percentage of the undissolved pressure-sensitive adhesive component remaining in the wire mesh relative to the weight of the pressure-sensitive adhesive layer before immersion in toluene. However, the weight of the substrate is deducted.

The pressure-sensitive adhesive film of the present invention is a pressure-sensitive adhesive film having a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive of the present invention on one side or both sides of a supporting substrate, and is particularly suitable as a heat-resistant pressure-sensitive adhesive film for masking.
In the present invention, "film" is meant to include "sheet" and "tape".

<Adhesive film>
The pressure-sensitive adhesive film can be produced, for example, as follows.
Such a pressure-sensitive adhesive film can be produced according to a generally known method for producing a pressure-sensitive adhesive film. For example, the above-mentioned pressure-sensitive adhesive composition is coated on one surface of a substrate, dried, A layer is formed, a release sheet is attached to the surface (opposite side of the surface in contact with the substrate), and if necessary curing is carried out, the adhesive composition containing the adhesive composition crosslinked on the substrate is contained. The pressure-sensitive adhesive film of the present invention having a pressure-sensitive adhesive layer is obtained.

  In addition, the above-mentioned pressure-sensitive adhesive composition is coated on a release sheet and dried to form a pressure-sensitive adhesive layer, and a substrate is bonded to the surface (opposite side of the surface in contact with the release sheet) The adhesive film of the present invention can also be obtained by curing according to

  At the time of use, the obtained adhesive film peels the said release sheet from an adhesive layer, and bonds an adhesive layer and a to-be-adhered body.

Examples of the substrate include polyester resins such as polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate, polyethylene terephthalate / isophthalate copolymer, etc .;
Polyolefin resins such as polyethylene, polypropylene and polymethylpentene;
Polyfluorinated ethylene resins such as polyvinyl fluoride, polyvinylidene fluoride, and polyfluorinated ethylene;
Polyamides such as nylon 6, nylon 6, 6 etc.
Vinyl polymers such as polyvinyl chloride, polyvinyl chloride / vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, vinylon and the like;
Cellulose-based resins such as cellulose triacetate and cellophane;
Acrylic resins such as polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate and polybutyl acrylate;
Polystyrene, polycarbonate, polyarylate, polyimide, synthetic resin film such as cycloolefin polymer, metal foil of aluminum, copper, iron, paper such as high quality paper, glassine paper, etc. Woven or non-woven fabric made of glass fiber, natural fiber, synthetic fiber etc. Can be mentioned. These substrates can be used as a single layer body or a multilayer body in which two or more kinds are laminated.

  Among them, particularly preferred is a substrate made of polyethylene terephthalate or polyimide, more preferably polyethylene terephthalate from the viewpoint of excellent adhesion to the pressure-sensitive adhesive layer, and in particular polyethylene terephthalate having a metal thin film layer, The adhesive strength with the pressure-sensitive adhesive layer is excellent, and the substrate can be stably maintained without corrosion of the metal thin film layer, which is preferable in that the effect of the pressure-sensitive adhesive used in the present invention can be remarkably exhibited.

  The thickness of the substrate is, for example, preferably 1 to 1,000 μm, particularly preferably 2 to 500 μm, and further preferably 3 to 300 μm.

  As the release sheet, for example, those obtained by release treatment of various synthetic resin sheets exemplified in the above-mentioned base material, paper, cloth, nonwoven fabric and the like can be used. Among them, it is preferable to use a silicon-based synthetic resin sheet.

  As a method of coating the above-mentioned adhesive composition on a substrate or a release sheet, for example, a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, a spray coater, a comma coater Etc.

  As drying conditions after coating the said adhesive composition, 60-140 degreeC of a drying temperature is preferable, Especially preferably, it is 80-120 degreeC. The drying time is preferably 0.5 to 30 minutes, and particularly preferably 1 to 5 minutes.

  When the pressure-sensitive adhesive composition is cured, the temperature is usually room temperature (23 ° C.) to 70 ° C., and the time is usually 1 to 30 days, and specifically, for example, 23 ° C. It is preferable to carry out under conditions such as 1 to 20 days, preferably 3 to 14 days at 23 ° C, and 1 to 10 days at 40 ° C.

  The thickness of the pressure-sensitive adhesive layer is preferably 2 to 500 μm, more preferably 5 to 200 μm, and still more preferably 10 to 100 μm. When the thickness of the pressure-sensitive adhesive layer is too thin, the adhesive strength tends to decrease, and when it is too thick, it becomes difficult to apply uniformly, and a defect such as air bubbles in the coating tends to easily occur. is there. In addition, when considering shock absorption, it is preferable to set it as 50 micrometers or more.

  In addition, the thickness of the said adhesive layer is calculated | required by deducting the measured value of the thickness of structural members other than an adhesive layer from the measured value of the thickness of the whole adhesive film using Mitutoyo company make "ID-C112B" It is a value.

  Furthermore, such an adhesive film may provide a release sheet in the outer side of an adhesive layer, and may protect an adhesive layer as needed. In the pressure-sensitive adhesive film in which the pressure-sensitive adhesive layer is formed on one side of the substrate, the surface of the substrate opposite to the pressure-sensitive adhesive layer is subjected to a release treatment to use the above-mentioned release-treated surface. It is also possible to protect the

  Moreover, although the adhesive film of this invention can be used for bonding of a various member, it is preferable to use as a masking film of the surface protection use of a to-be-adhered body especially. Even if the pressure-sensitive adhesive layer provided in the pressure-sensitive adhesive film is exposed to a high-temperature environment, the increase in the adhesive strength is suppressed, and the pressure-sensitive adhesive layer It is because it is hard to produce contamination, such as an adhesive remaining on a to-be-adhered body.

Therefore, the pressure-sensitive adhesive film of the present invention can be suitably used as a heat-resistant pressure-sensitive adhesive film for masking because it is particularly excellent in heat resistance.
For example, the heat-resistant adhesive film for masking of the present invention is attached to an adherend using the adhesive force of the pressure-sensitive adhesive layer, and the heat-resistant adhesive film for masking attached to the adherend is attached to each adherend By heating at 120 ° C. or higher and peeling the heat-resistant adhesive film for masking from this adherend from the adherend, masking is accurately performed, and an adherend not contaminated with the pressure-sensitive adhesive layer is obtained. be able to.

  The heat-resistant adhesive film according to the present invention temporarily holds a product as a heat-resistant adhesive film for temporary surface protection, for temporarily protecting the surface of a circuit substrate such as an FPC substrate or an ITO transparent electrode layer, for example. -It can be used as a heat-resistant adhesive film for temporary fixation for fixing for reinforcement.

Examples of the adherend to which such a heat-resistant adhesive film is to be attached include the following base materials.
Metal plate or metal foil of aluminum, copper, iron, stainless steel, magnesium, nickel, titanium etc.
Polyester resins such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyethylene terephthalate / isophthalate copolymer, ester acrylate;
Polyethylene, chlorinated polyethylene, chlorsulfonated polyethylene, ethylene propylene rubber, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-isobutyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-methacryl Polyolefin resin such as acid copolymer, ionomer, polypropylene, polyallomer polybutylene, polymethylpentene;
Polyfluorinated ethylene-based resins such as polyvinyl fluoride, polyvinylidene fluoride, polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, etc.
Polystyrene, poly (α-methylstyrene), acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, acrylonitrile-styrene-acrylate copolymer;
Polyalkyl (meth) acrylates such as poly (methyl methacrylate), poly (ethyl methacrylate), poly (ethyl acrylate) and poly (butyl acrylate), acrylics such as methyl methacrylate-styrene copolymer, methyl methacrylate-α-methyl styrene copolymer resin;
Polyvinyl chloride, plasticized polyvinyl chloride, ABS modified polyvinyl chloride, post-chlorinated polyvinyl chloride, polyvinyl chloride-acrylic resin alloy, vinyl chloride-propylene copolymer, vinyl chloride-vinyl acetate copolymer, poly chloride Polyvinyl chloride polymers such as vinylidene and its derivatives;
Polyvinyl acetate, polyvinyl alcohol, polyvinyl formal, polyvinyl butyral, ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, polyvinyl acetate such as vinylon, and derivatives thereof;
Polyvinyl methyl ether, polyvinyl methyl ketone;
Polyformaldehyde, acetal copolymer, polyethylene oxide, polypropylene oxide, chlorinated polyether, phenoxy resin, polyether such as polyphenylene oxide;
Fluorinated resins such as polytelora fluoroethylene, polychlorotrifluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, polyvinylidene fluoride, chlorotrifluoroethylene-vinylidene fluoride copolymer;
Polycarbonate, polycarbonate ABS alloy;
Nylon (polyamide) such as nylon, nylon-6, nylon-6,6, nylon-6 / 6,6 copolymer, nylon-6,10, nylon-6,12, nylon-11, nylon-12, etc .;
Butadiene-Styrene copolymer, Butadiene type plastic;
Polyimide and derivatives thereof, polysulfone, polyphenylene sulfide, high acrylonitrile copolymer;
Silicone resins, semi-inorganic and inorganic polymers;
Phenolic resin such as phenolic resin, phenol-furfural resin, modified phenolic resin and derivatives thereof;
Formalin resin such as furan resin, xylene resin, aniline resin, acetone-formaldehyde resin;
Unsaturated polyester and alkyd resin;
Epoxy resin such as bisphenol type epoxy resin, epoxy resin composite material, alicyclic epoxy resin, epoxy novolac, biphenyl type epoxy resin, epoxy acrylate, etc.
Polyurethane, polyurethane foam, polyurethane acrylate, etc .;
Allyl resins such as diallyl phthalate resin, triallyl cyanurate resin, polyallyl sulfone, allyl diglycol carbonate, polyallyl ether, polyarylate;
Cellulose-based resins such as cellulose-based plastics, cellulose acetate, cellulose propionate, cellulose acetate butyrate, ethyl cellulose, nitrocellulose and celluloid.

In particular, as a material of a heat-resistant adherend, a metal plate or metal foil of aluminum, copper, iron, stainless steel, magnesium, nickel, titanium, etc .;
Polyester resins such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyethylene terephthalate / isophthalate copolymer, ester acrylate;
Polyfluorinated ethylene-based resins such as polyvinyl fluoride, polyvinylidene fluoride, polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, etc.
Polyimides and their derivatives;
Bisphenol type epoxy resin, epoxy resin composite material, alicyclic epoxy resin, epoxy novolac, epoxy resin such as biphenyl type epoxy resin, epoxy acrylate, etc. are preferably used.

As a use of the heat-resistant adhesive film obtained by using the pressure-sensitive adhesive composition for heat-resistant adhesive film of the present invention, a carrier film for a process such as a printed substrate, particularly a flexible printed substrate;
Curling of films and foils with heating process, wrinkles, protective films to prevent contamination;
Protective film for printed circuit board solder plating;
Film for insulation and heat protection such as heat resistant transformer;
Film for masking during solder reflow process of electronic circuit board;
Various temporary fixing and film for protection of parts;
Through-hole sealing film;
Applications such as surface protection films of touch panel related members such as ITO transparent electrode layers can be mentioned, and it can be widely used for masking applications requiring heat resistance and temporary fixing applications in general. In particular, a heat-resistant adhesive film for masking is preferred.

  As a usage method of the heat-resistant adhesive film for masking of this invention manufactured using the adhesive composition for heat-resistant adhesive films of this invention, when a heating process is included in the manufacturing process of a to-be-adhered body, for example, a heating process Methods for temporarily surface protecting the adherend to be For example, as a method of using an adherend, the heat-resistant adhesive film for masking of the present invention is attached to the adherend surface and subjected to a heating step of usually 120 ° C. or more, preferably 150 ° C. or more, particularly preferably 170 ° C. or more Thereafter, the heat-resistant adhesive film for masking may be peeled off from the surface of the adherend.

  The heat-resistant adhesive film for masking of the present invention is less likely to cause contamination such as adhesive residue [an adhesive layer (adhesive agent) remains] on the adherend when it is peeled off from the adherend after being used under high temperature conditions. The possibility of contamination in the process of manufacturing the adherend is reduced. Moreover, since the heat-resistant adhesive film for masking of the present invention is less likely to cause corrosion on a metal adherend, the possibility of causing a defect in the final product is also reduced.

EXAMPLES Hereinafter, the present invention will be more specifically described by way of examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the examples, "part" and "%" mean weight basis.
The weight average molecular weight, glass transition temperature, acid value, and gel fraction of the pressure-sensitive adhesive in the following examples were measured according to the method described above.

<Production of polyester resin>
In the following production examples, each component was blended with the total of carboxylic acids used in the esterification reaction as 1 mole.

[Production of Polyester Resin (A-1)]
In a reaction vessel equipped with a thermometer, a stirrer, a rectification column, and a nitrogen introduction pipe, 495 parts (0.9 mol) of sebacic acid (SebA) as a divalent carboxylic acid, and 45 parts (0. 1 mol), 283 parts (1 mol) of neopentyl glycol (NPG) as a polyol, 64 parts (0.2 mol) of 1,6-hexanediol (1,6 HG), 0.3 parts of tetrabutyl titanate as a catalyst The temperature was increased over 2 hours until the internal temperature reached 260 ° C., and the esterification reaction was performed at 260 ° C. for 3 hours.
Thereafter, the internal temperature is lowered to 170 ° C., 113 parts (0.19 mole) of pyromellitic anhydride (PMAn) is added as an acid anhydride of a trivalent or higher carboxylic acid, and chain extension reaction is carried out for 1 hour. Based resin (A-1) was manufactured.
The weight average molecular weight of the polyester resin (A-1) was 28,900, the glass transition temperature (Tg) was -32 ° C, and the acid value was 70.1 mg KOH / g. In addition, the finished composition (%) was SebA / IPA / NPG / 1, 6HG / PMAn = 45.7 / 4.0 / 30.8 / 7.0 / 12.5. The product of the acid value and the weight average molecular weight was 2,025,890.

[Production of Polyester Resin (A-2)]
In a reaction vessel equipped with a thermometer, a stirrer, a rectification column, and a nitrogen introduction pipe, 543 parts (0.9 mol) of sebacic acid (SebA) as a divalent carboxylic acid and 50 parts (0. 1 mol), 286 parts (1 mol) of neopentyl glycol (NPG) as a polyol, 63 parts (0.2 mol) of 1,6-hexanediol (1,6 HG), 0.3 parts of tetrabutyl titanate as a catalyst The temperature was increased over 2 hours until the internal temperature reached 260 ° C., and the esterification reaction was performed at 260 ° C. for 3 hours.
Thereafter, the internal temperature is lowered to 170 ° C., 59 parts (0.09 mol) of pyromellitic anhydride (PMAn) is added as an acid anhydride of a trivalent or higher carboxylic acid, and chain extension reaction is carried out for 1 hour. Based resin (A-2) was manufactured.
The weight average molecular weight of the polyester resin (A-2) was 25,700, the glass transition temperature (Tg) was -42 ° C, and the acid value was 49.0 mg KOH / g. In addition, the finished composition (%) was SebA / IPA / NPG / 1, 6HG / PMAn = 51.1 / 4.5 / 31.7 / 7.1 / 5.6. The product of the acid value and the weight average molecular weight was 1,259,300.

[Production of polyester resin (A-3)]
A polyester-based resin (A-3) was prepared in the same manner as in the production of the polyester-based resin (A-1) except that the internal temperature was lowered to 140 ° C. and pyromellitic anhydride was added to perform chain extension reaction. Manufactured.
The weight average molecular weight of the polyester resin (A-3) was 5,500, the glass transition temperature (Tg) was -30 ° C, and the acid value was 96 mg KOH / g. The product of the acid value and the weight average molecular weight was 528,000.

[Production of Polyester Resin (A'-1)]
9.6 parts (0.2 mol) of isophthalic acid and 46.8 parts of sebacic acid as polyvalent carboxylic acids in a reaction vessel equipped with a heating device, thermometer, stirrer, rectification column, nitrogen introducing pipe and vacuum device Parts (0.8 mol), 27.1 parts (0.9 mol) of neopentyl glycol as a polyol, 13.0 parts (0.5 mol) of 1,4-butanediol, and 1,6-hexanediol 3.0 Parts (0.087 moles) and 0.5 parts (0.013 moles) of trimethylolpropane, and 0.01 parts of tetrabutyl titanate as a catalyst, gradually raising the temperature to 250 ° C., taking 4 hours An esterification reaction was performed.
Thereafter, the internal temperature is raised to 260 ° C., 0.01 part of tetrabutyl titanate is charged as a catalyst, the pressure is reduced to 1.33 hPa, and the polymerization reaction is performed over 3 hours to produce a polyester resin (A′-1). did.
The weight average molecular weight of the obtained polyester resin (A′-1) was 70,000, the glass transition temperature was −50 ° C., and the acid value was 0.4 mg KOH / g. The product of the acid value and the weight average molecular weight was 28,000.

<Manufacture of polyester resin (A'-2)>
A reaction vessel equipped with a heating device, thermometer, stirrer, rectification column, nitrogen introducing pipe and vacuum device, 680.6 parts (1.0 mol) of Pripol 1009 as polyvalent carboxylic acids, Pripol as polyol 319.4 parts (0.5 mol) of 2033 and 0.2 parts of tetrabutyltitanate as a catalyst were charged, and the temperature was gradually raised to an internal temperature of 240 ° C., and an esterification reaction was performed over 4 hours. Thereafter, the internal temperature was 240 ° C., the pressure was reduced to 1.33 hPa, and the esterification reaction was continued for 3 hours to produce a polyester resin (A′-2).
The weight average molecular weight of the polyester resin (A′-2) was 4,340, the glass transition temperature was −45 ° C., and the acid value was 66.6 mg KOH / g. Further, the finished composition (%) was pripol 1009 / pripol 2033 = 66.8 / 33.2. The product of the acid value and the weight average molecular weight was 289,044.

<Production of polyester-based pressure-sensitive adhesive composition>
The polyester resins (A-1) to (A-3) and (A'-2) obtained above are each diluted to a solid concentration of 50% using a solution of methyl ethyl ketone: 2-propanol = 1: 1. , (A'-1) was diluted with ethyl acetate to a solid concentration of 50% and used in the following Examples and Comparative Examples.

Example 1
5 parts of an epoxy-based crosslinking agent (manufactured by Mitsubishi Gas Chemical Co., Ltd., Tetrad X) with respect to 100 parts of the solid content of the polyester-based resin (A-1) solution obtained above, a hindered phenol-based antioxidant (BASF Corporation) 0.1 parts of IRGANOX1010 manufactured by Toray Industries, Ltd. was blended to obtain a polyester-based pressure sensitive adhesive composition.
The resulting polyester-based pressure-sensitive adhesive composition is applied to a polyethylene terephthalate (PET) film (100 μm in thickness) as a substrate so that the thickness after drying is about 50 μm, and then dried at 100 ° C. for 3 minutes The agent layer was formed. Thereafter, a release-treated PET film (release film) is adhered to the above-mentioned adhesive layer to protect the surface, and aged for 10 days under an atmosphere of a temperature of 40 ° C., an adhesive film (heat-resistant adhesive film) I got

[Embodiments 2 and 3]
A pressure-sensitive adhesive film (heat-resistant pressure-sensitive adhesive film) was obtained in the same manner as in Example 1, except that the compounding amount of the crosslinking agent was changed as shown in Table 1.

[Examples 4 to 8, Comparative Examples 1 to 3]
An adhesive film (heat-resistant adhesive film) was obtained in the same manner as in Example 1 except that the polyester resin shown in Table 1 was used and the crosslinking agent was blended as shown in Table 1.

Comparative Examples 4 and 5
An isocyanate-based crosslinking agent (Coronanate HX, manufactured by Tosoh Corp.) in an amount shown in Table 1 is blended with 100 parts of the solid content of the polyester-based resin (A'-1) solution obtained above, and a polyester-based pressure-sensitive adhesive An adhesive film (heat-resistant adhesive film) was obtained in the same manner as in Example 1 except that the composition was obtained.

  While measuring the gel fraction (%) of the pressure-sensitive adhesive using each of the obtained pressure-sensitive adhesive films (heat-resistant pressure-sensitive adhesive films), evaluation of the adhesive strength, adherend contamination and dent marks resistance is performed as described below. went. The results are shown in Table 1 below.

[Adhesive force]
SUS-BA and alkali-free glass were prepared as adherends. The adhesive film (heat-resistant adhesive film) obtained above is cut at 25 × 200 mm under an environment of 23 ° C. and 50% RH, and then the release film is peeled off, and the adhesive layer side is made of SUS-BA or alkali-free glass. It was made to abut, 2 kg roller was reciprocated, and pressure sticking was carried out. Then, after standing for 30 minutes in the same atmosphere, using an autograph (Autograph AGS-H 500N manufactured by Shimadzu Corporation), measure the 180 degree peel strength (N / 25 mm) at a peel speed of 300 mm / min. The following criteria were evaluated.
◎: 0.3 N / 25 mm or less.
○: More than 0.3 N / 25 mm and less than 0.5 N / 25 mm.
X: more than 0.5 N / 25 mm.

[Heat resistant adhesive strength]
Each adhesive film (heat-resistant adhesive film) was stuck on each adherend similarly to the above. Then, after storing for 1 day (24 hours) in a 150 ° C. incubator, after standing for 30 minutes under an environment of 23 ° C. and 50% RH, an autograph (Autograph AGS-H 500 N, manufactured by Shimadzu Corporation) The peel strength (N / 25 mm) was measured at a peel speed of 300 mm / min using the above, and evaluated according to the following criteria.
◎: 2.5 N / 25 mm or less.
○: more than 2.5 N / 25 mm and less than 10 N / 25 mm.
X: more than 10 N / 25 mm.

[Adhesive body contamination]
The adherend after measurement of the heat-resistant adhesive strength was visually observed, and the presence or absence of adhesive residue was evaluated according to the following criteria.
○: The adhesive residue is not visible at all.
Fair: I can see after sticking slightly.
X: Adhesive residue is clearly visible.

[Dentation resistance]
With respect to each obtained adhesive film (heat-resistant adhesive film), a 2 kg roller was rolled on the adhesive film from the release film side, the adhesive layer was observed visually, and the following references | standards evaluated.
○: No change.
X: There is a nick.

From the results in Table 1 above, the pressure-sensitive adhesive film of the present invention has a sufficiently low adhesive strength in the state of being attached to an adherend, and even when used under a high temperature environment, from the adherend It can be seen that contamination such as the adhesive remaining on the adherend is less likely to occur when peeled off, and the heat-resistant adhesive strength is also low.
Therefore, it is understood that the polyester-based pressure-sensitive adhesive composition, the polyester-based pressure-sensitive adhesive, and the pressure-sensitive adhesive composition for a heat-resistant adhesive film used therein are suitable as the pressure-sensitive adhesive layer of a heat-resistant adhesive film for masking.
On the other hand, in Comparative Examples 1 to 3 which are conventional products, the pressure-sensitive adhesive layer is too soft to peel off the PET film or a dent is generated, and the adhesive strength is high. , Was not suitable for masking. In particular, in Comparative Example 1, the peeling film could not be peeled smoothly, and when it was peeled forcibly, the pressure-sensitive adhesive layer was cohesively broken, so that it was not possible to measure the adhesive strength and the heat-resistant adhesive strength itself. Further, in Comparative Examples 4 and 5, the adhesion after heat resistance was too high, and both were difficult to withstand use as a heat-resistant adhesive film.

Moreover, it dilutes with the dilution solvent shown in Table 2 so that solid content concentration may be 50% using said polyester-based resin (A-1), and the solid of the obtained polyester-based resin (A-1) solution is carried out. The pot life was evaluated about what mixed the epoxy type crosslinking agent (Mitsubishi Gas Chemical company make, Tetrad X) by the compounding quantity shown to following Table 2 with respect to 100 parts of parts. The evaluation criteria are as follows, and the results are shown in Table 2 below.
○: No significant thickening is observed even after 2 hours of mixing.
X: A clear thickening is observed within 2 hours after mixing.

  From the results of Table 2 above, while those diluted with solvent only with methyl ethyl ketone are inferior in pot life, use of 2-propanol results in superior pot life.

  The pressure-sensitive adhesive composition of the present invention may be suitably used as a pressure-sensitive adhesive layer of a heat-resistant adhesive film for masking, because the change over time such as increase in adhesion is small even when used under high temperature environment. it can.

Claims (14)

  A polyester-based pressure-sensitive adhesive composition comprising a polyester-based resin having a carboxy group derived from at least one of a trivalent or higher carboxylic acid and an acid anhydride thereof in at least one of the side chain and the end of the molecule.   A polyester-based pressure-sensitive adhesive composition comprising a polyester-based resin having a product of an acid value (mg KOH / g) and a weight average molecular weight of 350,000 or more.   The polyester-based pressure-sensitive adhesive composition according to claim 1 or 2, wherein the glass transition temperature of the polyester-based resin is -90 to 20 ° C.   The polyester-based pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein the acid value of the polyester-based resin is 5 mg KOH / g or more.   The polyester-based pressure-sensitive adhesive composition according to any one of claims 1 to 4, wherein the weight average molecular weight of the polyester-based resin is 2,000 to 500,000.   The polyester-based pressure-sensitive adhesive composition according to any one of claims 1 to 5, further comprising a crosslinking agent.   The polyester-based pressure-sensitive adhesive composition according to claim 6, wherein the crosslinking agent is a compound having an epoxy group.   A polyester-based pressure-sensitive adhesive comprising the polyester-based pressure-sensitive adhesive composition according to any one of claims 1 to 7 crosslinked.   The polyester-based pressure-sensitive adhesive according to claim 8, wherein the gel fraction of the polyester-based pressure-sensitive adhesive is 70% by weight or more.   A pressure-sensitive adhesive film comprising a pressure-sensitive adhesive layer containing the polyester-based pressure-sensitive adhesive according to claim 8 or 9.   A pressure-sensitive adhesive composition for a heat-resistant adhesive film comprising the polyester-based pressure-sensitive adhesive composition according to any one of claims 1 to 7.   A heat-resistant adhesive film for masking comprising a pressure-sensitive adhesive layer for a heat-resistant adhesive film comprising the pressure-sensitive adhesive composition for a heat-resistant adhesive film according to claim 11.   A process for affixing the heat-resistant adhesive film for masking according to claim 12 to an adherend using the adhesive force of the pressure-sensitive adhesive layer for heat-resistant adhesive film, and the heat-resistant adhesive film for masking attached to the adherend A method of using the heat-resistant adhesive film for masking comprising the steps of heating the adherends to a temperature of at least 120 ° C. and separating the heat-resistant adhesive film for masking from the adherends via the heating step; .   A polyester-based pressure-sensitive adhesive composition comprising a polyester-based resin having an acid value of 5 mg KOH / g or more and a weight-average molecular weight of 2,000 or more, an epoxy-based crosslinking agent, and an alcohol-based solvent.