Adhesive and adhesive sheet

Abstract

To provide an adhesive made from an environmentally friendly plant-derived raw material, which has good adhesive properties and excellent processability, dent resistance and transparency.SOLUTION: There is provided an adhesive obtained by crosslinking an adhesive composition comprising a polyester-based resin (i) having a structural site derived from polyvalent carboxylic acids (a) and a structural site derived from a polyol component (b) and a tackifier resin (viii), wherein the polyester-based resin contains 60 wt.% or more of a structural site derived from at least one selected from the group consisting of dimer acids, sebacic acids and a dimer diol based on the polyester-based resin (i) and contains a glycol (b1) having an even number of carbon atoms as the polyol component (b) (provided that a dimer diol is excluded), the ester group concentration of the polyester-based resin (i) is 2 mmol / g or more and the adhesive strength (α) under the specified conditions is 1 N / 25 mm or more.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a polyester-based adhesive and an adhesive sheet. More specifically, the present invention relates to an adhesive using a plant-derived raw material that is friendly to the global environment, which has good adhesive physical properties to various adherends such as metals and plastics, and is excellent in processability, impact resistance, and transparency, and an adhesive sheet thereof.

Background Art

[0002] In recent years, from the viewpoints of miniaturization and weight reduction of products, adhesives have been used for joining components, etc. As such adhesives, adhesives using a polyester-based resin and having excellent adhesive strength have also been studied.

[0003] On the other hand, recently, as part of measures to address the depletion of fossil resources and global warming, the use of plant-derived raw materials, which are renewable resources, has been recommended, and there is a demand for adhesives with a high degree of bioplasticity using plant-derived raw materials that are friendly to the global environment.

[0004] As such a polyester-based adhesive using a plant-derived raw material, Patent Document 1 discloses a low moisture permeability adhesive sheet having an adhesive layer with a moisture permeability of 200 g / m 2 or less, which contains, as a main component, a polyester-based polymer having an alkyl group in the molecular side chain obtained by subjecting a plant-derived dicarboxylic acid and a plant-derived diol to a condensation reaction.

[0005] Further, Patent Document 2 proposes an adhesive sheet using a polyester containing at least a lactic acid unit, a dibasic acid unit, and a glycol unit, wherein the dibasic acid unit contains dimer acid, and the polyester has a glass transition temperature of -70 to -20°C, a weight average molecular weight of 20,000 to 300,000, and a hydroxyl value of 1 to 100 mgKOH / g when measured at a heating rate of 20°C / min using a differential scanning calorimeter.

[0006] Although general polyester resins are crystalline resins, in the application of adhesives, how to break the crystallinity becomes important.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, in the disclosed technology of Patent Document 1 above, a long-chain alkyl-based raw material is used, and the resulting polyester resin itself is very soft. Therefore, although it is an adhesive with a high degree of bioplastic and environmentally friendly, the adhesive is soft and extremely inferior in handleability when made into a narrow adhesive sheet. Moreover, since the resin itself is too soft, it is difficult to produce a clean adhesive sheet before cross-linking, and the adhesive also has poor resistance to indentation. Further improvement is required in consideration of achieving both environmental compatibility and adhesive performance.

[0009] For example, in an adhesive sheet used for fixing a display protection member (such as a cover glass) of a portable electronic device, it is very important to narrow the width of the adhesive sheet from the viewpoints of increasing the screen size of the information display part, improving the design property, and improving the design freedom.

[0010] When the width of the adhesive sheet is narrowed, it becomes difficult to handle the adhesive sheet. That is, when the width is narrowed, the surface area size of the adhesive sheet becomes smaller, but even in the state with the separator film, the area of the exposed adhesive portion on the side surface of the adhesive sheet does not change, so it becomes difficult to handle. Furthermore, when narrowing the width of the adhesive sheet, the adhesive sheet needs to be slit. However, since the slit width becomes narrower, problems such as the adhesive layer being pulled by the slit blade are likely to occur, which also affects the performance of the adhesive sheet and causes problems. Moreover, when the adhesive adheres to the blade, the processability and workability will also decrease.

[0011] In addition, for an adhesive sheet corresponding to the narrowing of the display protection member of a portable electronic device, etc., an adhesive sheet is required that does not stick to the side surface and has little deformation of the adhesive layer and adhesion of the adhesive to the blade even when slit. Furthermore, an adhesive excellent in impact resistance without impact marks against external forces applied to the adhesive layer and excellent in transparency for detecting abnormalities such as foreign matter biting is required.

[0012] Even in the disclosed technology of Patent Document 2 above, although an adhesive with a high degree of biodegradability and environmentally friendly has been obtained, the adhesive is still not sufficient in terms of the adhesive physical properties to the adherend. In particular, the balance between the holding force and the adhesive force required for double-sided tapes, etc., is not sufficient, and the adhesive physical properties for adherends that are difficult to adhere to, such as plastic substrates, especially polyolefin substrates, are still not satisfactory, and further improvement is required.

[0013] Furthermore, the polylactic acid-based polyester disclosed in the technology of Patent Document 2 above is expected as a plant-derived material, but it is likely to undergo hydrolysis and requires high wet heat durability. As an adhesive use, it is very difficult to use and its use is restricted.

[0014] Therefore, in the present invention, under such circumstances, an adhesive using a plant-derived raw material that is friendly to the global environment, and an adhesive and an adhesive sheet are provided, which have good adhesive physical properties with respect to various adherends and are excellent in workability, impact resistance, and transparency.

Means for Solving the Problems

[0015] However, the present inventor has found that in an adhesive in which an adhesive composition containing a polyester resin is crosslinked, when using a polyester resin with a high degree of bioplasticity using at least one plant-derived raw material such as dimer acids, sebacic acids, and dimer diols, a glycol component having an even number of carbon atoms is used as the polyol component constituting the polyester resin, and the ester group concentration of the polyester resin is increased to set a predetermined adhesive force high, it is possible to obtain an adhesive that is friendly to the global environment, has good adhesive physical properties with respect to various adherends, and is excellent in workability, impact resistance, and transparency even when made narrower.

[0016] That is, the present invention is an adhesive in which an adhesive composition containing a polyester resin (i) having a structural part derived from polycarboxylic acids (a) and a structural part derived from a polyol component (b) is crosslinked, the above polyester resin (i) contains a structural part derived from at least one selected from the group consisting of dimer acids, sebacic acids, and dimer diols in an amount of 60% by weight or more based on the polyester resin (i), contains a glycol (b1) having an even number of carbon atoms as the above polyol component (b) (however, dimer diol is excluded), the ester group concentration of the above polyester resin (i) is 2 mmol / g or more, The first gist of the present invention is an adhesive having an adhesive force (α) of 1 N / 25 mm or more under the following conditions. Adhesive force (α): When an adhesive layer made of an adhesive forms an adhesive sheet on a base material, after being attached to an adherend of SUS-BA plate and left standing for 30 minutes in an environment of 23°C and 50% RH, the 180-degree peel strength (N / 25 mm) at a peel rate of 300 mm / min with respect to the adherend.

[0017] Further, the present invention relates to an adhesive in which an adhesive composition containing a polyester resin (ii) having a bioplastic degree of 60% or more is crosslinked, wherein the polyester resin (ii) has a structural site derived from polycarboxylic acids (a) and a structural site derived from a polyol component (b), and the polyol component (b) contains a glycol (b1) having an even number of carbon atoms (however, dimer diol is excluded), the ester group concentration of the polyester resin (ii) is 2 mmol / g or more, and the second gist is an adhesive having an adhesive strength (α) of 1 N / 25 mm or more under the following conditions. Adhesive strength (α): When an adhesive layer made of an adhesive forms an adhesive sheet on a base material, after being attached to a adherend of SUS-BA plate and left standing for 30 minutes in an environment of 23°C and 50% RH, the 180-degree peel strength (N / 25 mm) at a peel rate of 300 mm / min with respect to the adherend.

[0018] Furthermore, in the present invention, the third gist is an adhesive sheet having an adhesive layer containing the adhesive of the first gist or the second gist.

[0019] Generally, as raw materials with a high bioplastic degree, most are long-chain alkyl-based materials. For example, sebacic acid derived from castor oil, dimer acid derived from oleic acid, dimer diol using such dimer acid, and the like. For example, sebacic acid is a monomer with very high crystallinity when made into a polyester resin, and the polyester resin derived from sebacic acid is used as a crystalline polyester resin. On the other hand, dimer acid and dimer diol are monomers used for softening the resin and improving water resistance. In order to improve their physical properties, it is advantageous that the ester group concentration is as low as possible, so it is preferable to lower the ester group concentration as much as possible.

[0020] In general, when attempting to prepare an adhesive using a polyester resin, it is necessary to lower the glass transition temperature. Therefore, a glycol material containing an alkyldicarboxylic acid and an alkyl group having 5 or more carbon atoms, for example, a branched glycol such as neopentyl glycol (5 carbon atoms), is used to disrupt the crystallinity and soften it with a glycol having a somewhat long chain such as 1,6 - hexanediol (6 carbon atoms). These glycol materials can disrupt the crystallinity of the polyester resin, lower the glass transition temperature, and improve the adhesive strength. When using a glycol having a small number of carbon atoms, that is, a glycol having 4 or fewer carbon atoms, since the softness is insufficient and the adhesive properties tend to be inadequate, it is generally considered that a glycol component having 4 or fewer carbon atoms as the main component is not usually used.

[0021] However, in the present invention, unexpectedly, although it is a polyester resin with a high degree of bioplastic, a glycol having an even number of carbon atoms is used as the polyol component, the molecular alignment is increased, and a design is made such that crystallization does not actually occur. Also, while using a plant - derived long - chain monomer, the ester group concentration is increased to achieve the object of the present invention.

[0022] For example, when an adhesive is made using a polyester resin using dimer acid and dimer diol as the main components, due to the influence of the long main chain and side - chain alkyl chains, it becomes a very soft resin, and the "impact resistance during the formation of the adhesive sheet" and the "processability when cutting the completed adhesive sheet into the required size, etc." are significantly inferior. In the present invention, for example, while using dimer acid and appropriately sebacic acid to make it soft, by using a small glycol such as ethylene glycol or 1,4 - butanediol as the glycol, the ester bond concentration, which is a hard component, is increased as much as possible to improve the impact resistance and processability of the adhesive made using the polyester resin.

[0023] Further, for example, when using a glycol component having an even number of carbon atoms such as ethylene glycol or 1,4-butanediol, as compared with the case of using a glycol component having an odd number of carbon atoms such as 1,3-propanediol, it is considered that a part of the polymer chain is likely to take a structure in which it is aligned, and the cohesive force inside the resin increases. As a result, it is presumed that the adhesive force required for the double-sided tape becomes higher.

Advantages of the Invention

[0024] The adhesive of the present invention is an adhesive in which an adhesive composition containing a polyester resin (i) having a structural site derived from a polyvalent carboxylic acid (a) and a structural site derived from a polyol component (b) is crosslinked. The polyester resin (i) contains a structural site derived from at least one selected from the group consisting of dimer acids, sebacic acids, and dimer diols in an amount of 60% by weight or more based on the polyester resin (i). The polyester resin is a polyester resin containing a glycol (b1) having an even number of carbon atoms as the polyol component (b) (however, dimer diol is excluded). The ester group concentration of the polyester resin (i) is 2 mmol / g or more, and the adhesive force (α) under the above conditions is 1 N / 25 mm or more. Therefore, it is an adhesive that is highly bio-based and friendly to the global environment, and contains a polyester resin having a high ester group concentration in the polyester resin. It has good adhesive physical properties for various adherends, and has excellent effects in workability, impact resistance, and transparency even when narrowed. Therefore, it is effectively used for a single-sided or double-sided adhesive sheet used for bonding optical members, a single-sided or double-sided adhesive sheet for fixing members of portable electronic devices, and a single-sided or double-sided adhesive sheet for fixing electronic members.

[0025] When the glycol (b1) having an even number of carbon atoms is an aliphatic glycol having a linear structure, an adhesive excellent in the balance between crystallinity and cohesive force can be obtained.

[0026] When the above polycarboxylic acids (a) contain 70 mol% or less of linear carboxylic acids (a1), an adhesive excellent in the balance between crystallinity and cohesive force can be obtained.

[0027] When the above polyol component (b) contains 10 to 100 mol% of a glycol (b1) having an even number of carbon atoms, an adhesive excellent in adhesive force can be obtained.

[0028] When the glycol (b1) having an even number of carbon atoms is a polyol having 4 or less carbon atoms, an adhesive excellent in production stability can be obtained.

[0029] When the acid value of the above polyester resin (i) is 10 mgKOH / g or less, an adhesive excellent in durability can be obtained.

[0030] When the biodegradable plastic degree of the above polyester resin (i) is 60% or more, an adhesive more friendly to the global environment can be obtained.

[0031] Further, the adhesive of the present invention is an adhesive in which an adhesive composition containing a polyester resin (ii) having a biodegradable plastic degree of 60% or more is crosslinked. The polyester resin (ii) has a structural part derived from polycarboxylic acids (a) and a structural part derived from a polyol component (b). The polyol component (b) is a polyester resin containing a glycol (b1) having an even number of carbon atoms (excluding dimer diol). The ester group concentration of the polyester resin (ii) is 2 mmol / g or more, and the adhesive force (α) under the above conditions is 1 N / 25 mm or more. Therefore, it is an adhesive that is highly biodegradable and friendly to the global environment, contains a polyester resin having a high ester group concentration of the polyester resin, has good adhesive physical properties to various adherends, and has excellent processability, impact resistance, and transparency even when narrowed. Therefore, it is effectively used for single-sided or double-sided adhesive sheets used for bonding optical members, single-sided or double-sided adhesive sheets for fixing members of portable electronic devices, fixing electronic members, etc.

[0032] When the above-mentioned adhesive composition further contains a hydrolysis inhibitor (iii), an adhesive excellent in long-term durability can be obtained.

[0033] When the above-mentioned adhesive composition further contains a crosslinking agent (iv), an adhesive excellent in adhesiveness can be obtained.

[0034] When the above-mentioned adhesive composition further contains a tackifier resin (vii), an adhesive excellent in adhesion characteristics can be obtained.

[0035] In addition, when the biodegradability of the adhesive is 60% or more, an adhesive more friendly to the global environment can be obtained.

Mode for Carrying Out the Invention

[0036] Hereinafter, the configuration of the present invention will be described in detail, but these show an example of a desirable embodiment. In the present invention, the term "carboxylic acids" includes, in addition to carboxylic acids, carboxylic acid derivatives such as hydrogenated products of carboxylic acids, carboxylates, carboxylic anhydrides, carboxylic acid halides, and carboxylic acid esters.

[0037] The adhesive composition for forming the adhesive of the present invention is an adhesive composition containing a polyester resin (i) having a structural site derived from a polyvalent carboxylic acid (a) and a structural site derived from a polyol component (b), and the polyester resin (i) contains a structural site derived from at least one selected from the group consisting of dimer acids, sebacic acids, and dimer diols in an amount of 60% by weight or more based on the polyester resin (i), contains a glycol (b1) having an even number of carbon atoms as the polyol component (b) (however, dimer diol is excluded), and contains a polyester resin having an ester group concentration of 2 mmol / g or more in the polyester resin (i).

[0038] In addition, the pressure-sensitive adhesive composition that forms the pressure-sensitive adhesive of the present invention is a pressure-sensitive adhesive composition containing a polyester resin (ii) with a bioplastic content of 60% or more. The polyester resin (ii) has a structural site derived from polycarboxylic acids (a) and a structural site derived from a polyol component (b). The polyester resin is a polyester resin containing a glycol (b1) having an even number of carbon atoms (excluding dimer diol) as the polyol component (b), and the ester group concentration of the polyester resin (ii) is 2 mmol / g or more.

[0039] Hereinafter, each component constituting the pressure-sensitive adhesive composition in the present invention will be sequentially described.

[0040] <Polyester resins (i) and (ii)> The polyester resins (i) and (ii) used in the present invention have a structural site derived from polycarboxylic acids (a) and a structural site derived from a polyol component (b). For example, they can be obtained by copolymerizing a copolymer component containing polycarboxylic acids (a) and a polyol component (b).

[0041] [Polycarboxylic acids (a)] In the present invention, in order to increase the bioplastic content, it is preferable to use plant-derived polycarboxylic acids. Examples of the plant-derived polycarboxylic acids include sebacic acids derived from castor oil, dimer acids (mainly having 36 or 44 carbon atoms) derived from oleic acid, linoleic acid, linolenic acid, erucic acid, etc., and succinic acids derived from glucose. In addition to plant-derived dimer acids, dimer acids derived from beef tallow can also be used as the dimer acids.

[0042] Among the polycarboxylic acids (a), it is preferable to use linear carboxylic acids (a1) in terms of ease of obtaining raw materials and ease of production. More preferably, they are linear carboxylic acids having 4 to 12 carbon atoms, and even more preferably, linear carboxylic acids having 6 to 10 carbon atoms. Sebacic acids are particularly preferable in that they lower the glass transition temperature and facilitate adjustment of the adhesive physical properties.

[0043] The polyester resins (i) and (ii) used in the present invention contain a structural site derived from the polycarboxylic acids (a). As the polycarboxylic acids (a), it is preferable to contain 70 mol% or less of linear carboxylic acids (a1), particularly preferably 5 to 70 mol%, and even more preferably 10 to 60 mol%. If such a content is too high, the crystallinity tends to increase easily. If it is too low, the production stability tends to decrease.

[0044] Also, as the polycarboxylic acids (a), it is preferable to use dimer acids (a2) in terms of being able to easily prevent crystallinity, and more preferably a hydrogenated product of dimer acid.

[0045] The above dimer acids (a2) are preferably contained in an amount of 40 mol% or more, particularly preferably 50 mol% or more, and even more preferably 60 mol% or more, based on the polycarboxylic acids (a). The upper limit is usually 100 mol%. If such a content is too low, the crystallinity tends to increase easily.

[0046] As the above polycarboxylic acids (a), it is also preferable to use linear carboxylic acids (a1) and dimer acids (a2) in combination. When these are used in combination, the molar ratio of (a1):(a2) is preferably 1:99 to 90:10, more preferably 5:95 to 60:40, and particularly preferably 10:90 to 50:50.

[0047] In addition, polycarboxylic acids other than the above may be used as long as the object of the present invention is not impaired. Examples of such polycarboxylic acids other than those described above include aliphatic dicarboxylic acids such as malonic acids, dimethylmalonic acids, glutaric acids, adipic acids, trimethyladipic acids, pimelic acids, 2,2-dimethylglutaric acids, azelaic acids, fumaric acids, maleic acids, itaconic acids, thiodipropionic acids, diglycolic acids, 1,9-nonanedicarboxylic acids; aromatic dicarboxylic acids such as phthalic acids, terephthalic acids, isophthalic acids, benzylmalonic acids, diphenic acids, 4,4'-oxydibenzoic acids, and naphthalenedicarboxylic acids such as 1,8-naphthalenedicarboxylic acids, 2,3-naphthalenedicarboxylic acids, 2,7-naphthalenedicarboxylic acids; alicyclic dicarboxylic acids such as 1,3-cyclopentanedicarboxylic acids, 1,2-cyclohexanedicarboxylic acids, 1,3-cyclopentanedicarboxylic acids, 1,4-cyclohexanedicarboxylic acids, 2,5-norbornanedicarboxylic acids, adamantanedicarboxylic acids; polyvalent carboxylic acids having three or more valences such as trimellitic acids, pyromellitic acids, adamantanetricarboxylic acids, trimesic acids, and the like.

[0048] The above polycarboxylic acids (a) are used singly or in combination of two or more.

[0049] [Polyol component (b)] In the present invention, in order to increase the degree of biodegradability, it is preferable to use a plant-derived polyol component. Examples of the above plant-derived polyol component include fatty acid ester-based diols derived from castor oil, dimer acids (mainly having 36 or 44 carbon atoms) derived from oleic acid, linoleic acid, linolenic acid, erucic acid, etc. and dimer diols obtained by diolizing hydrogenated products thereof, bioethylene glycol, biopropylene glycol, biobutylene glycol, etc. Among them, bioethylene glycol and biopropanediol (1,3-propanediol) are preferable in terms of easily increasing the ester group concentration, and bioethylene glycol is particularly preferable.

[0050] In the present invention, as the polyol component (b), it is necessary to use a glycol (b1) having an even number of carbon atoms (however, dimer diol is excluded) from the viewpoint of increasing the molecular alignment and imparting cohesive force while disrupting crystallinity.

[0051] Examples of the glycol (b1) having an even number of carbon atoms include aliphatic glycols having a linear structure such as ethylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol, etc., and aliphatic glycols having a branched structure such as 1,2-butanediol, 1,3-butanediol, dipropylene glycol, 2,4-dimethyl-2-ethylhexane-1,3-diol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, etc. Alicyclic glycols such as 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, adamantane diol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, etc. Aromatic glycols such as 4,4'-thiodiphenol, bisphenol S, 4,4'-dihydroxybiphenyl, o-, m- and p-dihydroxybenzene, 2,5-naphthalenediol, p-xylene diol, etc.; and their ethylene oxide and propylene oxide adducts. And the like can be mentioned. It is also preferable that such a glycol (b1) having an even number of carbon atoms is derived from plants.

[0052] Among the above-mentioned glycols (b1) having an even number of carbon atoms, aliphatic glycols are preferable, and in particular, it is preferable to use an aliphatic glycol having a linear structure from the viewpoint of the balance between crystallinity and cohesive force.

[0053] Further, from the viewpoint of increasing the ester bond concentration or manufacturing stability, it is preferable to use a glycol (b1) having an even number of carbon atoms and having 4 or less carbon atoms, and particularly preferably a glycol having 2 carbon atoms.

[0054] Preferable specific examples of the glycol (b1) having an even number of carbon atoms used in the present invention include aliphatic glycols having a linear structure and having 4 or less carbon atoms such as ethylene glycol, diethylene glycol, and 1,4-butanediol. Among them, ethylene glycol, 1,4-butanediol, and particularly ethylene glycol are preferable.

[0055] In the present invention, the content of the glycol (b1) having an even number of carbon atoms is preferably 10 to 100 mol% with respect to the total polyol component (b), particularly preferably 30 to 99.9 mol%, more preferably 50 to 99.7 mol%, and particularly preferably 70 to 99.6 mol%. If the content is too small, the adhesion performance tends to decrease.

[0056] In the present invention, a polyol component (b) other than the glycol (b1) having an even number of carbon atoms may be used as long as the object of the present invention is not impaired. Examples of the polyol component (b) other than the glycol (b1) having an even number of carbon atoms include glycols having an odd number of carbon atoms, polyhydric alcohols having a trivalent or higher valence, and the like.

[0057] Examples of the glycol having an odd number of carbon atoms include aliphatic glycols having a linear structure such as 1,3-propanediol, 1,5-pentanediol, and 1,9-nonanediol; aliphatic glycols having a branched structure such as 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, and 2,2,4-trimethyl-1,6-hexanediol; alicyclic glycols such as spiroglycol; Aromatic glycols such as 4,4'-methylenediphenol, bisphenol A, bisphenol fluorene; and their ethylene oxide and propylene oxide adducts; etc. can be mentioned.

[0058] Examples of the above trivalent or higher polyhydric alcohols include pentaerythritol, dipentaerythritol, tripentaerythritol, glycerin, trimethylolpropane, trimethylolethane, 1,3,6-hexanetriol, adamantanetriol, etc.

[0059] Among these, glycols with an odd number of carbon atoms are preferred in terms of disrupting crystallinity and improving solution stability, and more preferably aliphatic glycols having a branched structure. Among them, from the perspective of versatility, 2,2-dimethyl-1,3-propanediol (neopentyl glycol) and 2-ethyl-2-isobutyl-1,3-propanediol are preferred.

[0060] Also, when the biodegradability of the polyvalent carboxylic acids (a) is high, for the polyol component (b), a polyol component not derived from plants may be used from the viewpoint of ease of polycondensation. However, even in that case, in order to increase the biodegradability, it is preferable to use a polyol having 4 or less carbon atoms, and particularly preferably a polyol having 2 carbon atoms. That is, when a polyol component (b) having a small number of carbon atoms of 4 or less is used, the weight ratio of carboxylic acids (a) having a high biodegradability as the polyester resins (i) and (ii) increases, and the biodegradability can be increased. Specific examples of the above polyol having 4 or less carbon atoms include ethylene glycol, 1,4-butanediol, etc.

[0061] The above polyol component (b) is used singly or in combination of two or more.

[0062] In addition to the above polyol component (b) and polycarboxylic acids (a), the use of a compound having both a carboxylic acid and a hydroxyl group in the molecule (for example, lactic acid, etc.) is possible as long as the effects of the present invention are not impaired. However, since lactic acid is liable to undergo hydrolysis, it is more preferable not to use it.

[0063] In order to obtain polyester resins (i) and (ii) having a high degree of biodegradability used in the present invention, it is preferable to contain at least one selected from the group consisting of dimer acids, sebacic acids and dimer diols in an amount of 60% by weight or more, more preferably 65% by weight or more, still more preferably 70% by weight or more, particularly preferably 80% by weight or more, based on the copolymer components of the polyester resin (i). The upper limit is 100% by weight. If such a content is low, the degree of biodegradability of the obtained polyester resins (i) and (ii) tends to be low, and the reduction of environmental load tends to be insufficient.

[0064] [Production of polyester resins (i) and (ii)] In the present invention, the polyester resins (i) and (ii) can be produced by subjecting polycarboxylic acids (a) and a polyol component (b) to a polycondensation reaction by a known method in the presence of a catalyst. In the polycondensation reaction, first, an esterification reaction or a transesterification reaction is carried out, and then a polycondensation reaction is carried out. When it is not necessary to obtain a high molecular weight, it may be produced only by an esterification reaction or a transesterification reaction.

[0065] In such an esterification reaction or transesterification reaction, a catalyst is usually used. Specifically, for example, titanium-based catalysts such as tetraisopropyl titanate and tetrabutyl titanate, antimony-based catalysts such as antimony trioxide, germanium-based catalysts such as germanium dioxide, and catalysts such as zinc acetate, manganese acetate and dibutyltin oxide can be mentioned, and one or more of these are used. Among these, antimony trioxide, tetrabutyl titanate, germanium dioxide and zinc acetate are preferable in view of the balance between high catalyst activity and the hue of the obtained reaction product.

[0066] The compounding amount of the above catalyst is preferably 1 to 10,000 ppm, particularly preferably 10 to 5,000 ppm, and even more preferably 20 to 3,000 ppm, based on the total copolymerization components (by weight). If such a compounding amount is too small, the polymerization reaction tends not to proceed sufficiently. If it is too large, there is no advantage such as shortening of the reaction time, and side reactions tend to occur easily.

[0067] Regarding the reaction temperature during the esterification reaction, 200 to 300 °C is preferable, particularly preferably 210 to 280 °C, and even more preferably 220 to 260 °C. If such a reaction temperature is too low, the reaction tends not to proceed sufficiently. If it is too high, side reactions such as decomposition tend to occur easily. Also, the pressure during the reaction is usually normal pressure.

[0068] As the reaction conditions for the polycondensation reaction carried out after the above esterification reaction or transesterification reaction, a catalyst similar to that used in the above esterification reaction or transesterification reaction is further compounded in a similar amount, and the reaction temperature is preferably 220 to 280 °C, particularly preferably 230 to 270 °C, and it is preferable to gradually reduce the pressure of the reaction system and finally react at 5 hPa or less. If such a reaction temperature is too low, the reaction tends not to proceed sufficiently. If it is too high, side reactions such as decomposition tend to occur easily.

[0069] Thus, the polyester resins (i) and (ii) used in the present invention are obtained.

[0070] In order to make the polyester resin (i) used in the present invention have a high degree of bioplastic, it is important that the polyester resin (i) contains a structural site derived from at least one selected from the group consisting of dimer acids, sebacic acids, and dimer diols in an amount of 60% by weight or more, preferably 65% by weight or more, more preferably 70% by weight or more, and particularly preferably 80% by weight or more. The upper limit is 100% by weight. If the content of such a structural site is small, the degree of bioplastic of the polyester resin (i) becomes low, and the reduction of the environmental load becomes insufficient.

[0071] The ester group concentration of the above polyester resins (i) and (ii) is 2 mmol / g or more, preferably 2.5 to 10 mmol / g, more preferably 2.7 to 7 mmol / g, and particularly preferably 3 to 5 mmol / g. If such an ester group concentration is too small, the polyester resin becomes soft and inferior in impact resistance and processability. As a method for adjusting the above ester group concentration to a predetermined range, for example, a method of selecting a polyol having 4 or less carbon atoms as the polyol component (b), a method of increasing the content of linear carboxylic acids (a1) as the polycarboxylic acids (a), a method of combining both, etc. can be mentioned.

[0072] The above ester group concentration (mmol / g) refers to the number of moles of ester bonds in 1 g of the polyester resin, and is obtained, for example, as a calculated value from the charged amount. Such a calculation method is a value obtained by dividing the smaller number of moles of the charged moles of the polycarboxylic acids (a) and the polyol component (b) by the total weight of the final product. An example of the calculation formula is shown below. In the case of using a monomer having both a carboxylic acid and a hydroxyl group, or producing a polyester from caprolactone, etc., the calculation method will be changed as appropriate.

[0073] <When the polycarboxylic acids (a) are less> Ester group concentration (mmol / g) = [(A1 / a1 × m1 + A2 / a2 × m2 + A3 / a3 × m3 ···) / Z] × 1000 A: Charged amount (g) of the polycarboxylic acids (a) a: Molecular weight of the polycarboxylic acids (a) m: Number of carboxy groups per molecule of the polycarboxylic acids (a) Z: Final weight (g)

[0074] <When the polyol component (b) is less> Ester group concentration (mmol / g) = [(B1 / b1 × n1 + B2 / b2 × n2 + B3 / b3 × n3 ···) / Z] × 1000 B: Charge amount (g) of polyol component (b) b: Molecular weight of polyol component (b) n: Number of hydroxyl groups per molecule of polyol component (b) Z: Final weight (g)

[0075] In addition, the ester group concentration can also be measured by a known method using NMR or the like.

[0076] In the present invention, the bioplastic degree of the polyester resin (i) is preferably 60% or more, more preferably 65% or more, still more preferably 70% or more, and particularly preferably 80% or more. If such bioplastic degree is low, the reduction of environmental load tends to be insufficient.

[0077] In addition, the bioplastic degree of the polyester resin (ii) is 60% or more, preferably 65% or more, more preferably 70% or more, and particularly preferably 80% or more. If such bioplastic degree is low, the reduction of environmental load becomes insufficient.

[0078] The upper limit of the above bioplastic degree is 100%. As a method for adjusting the bioplastic degree to a predetermined range, using mainly plant-derived polycarboxylic acids and plant-derived polyol components can be mentioned. In terms of being able to efficiently increase the bioplastic degree, it is particularly preferable that the polycarboxylic acids (a) are of plant origin.

[0079] Here, the bioplastic degree of the polyester resins (i) and (ii) refers to the ratio of the carbon of the plant-derived raw materials used in the production of the polyester resins (i) and (ii) incorporated into the resin with respect to the total carbon of the polyester resins (i) and (ii), and the calculation method is as follows.

[0080] Regarding the biodegradability of polycarboxylic acids (a), polyol components (b), and other components (e.g., compounds having carboxy groups and hydroxyl groups in the molecule), it shall be determined from the weighted average of the biodegradabilities of each component.

[0081] (Calculation method) <In the case involving polycondensation reaction> Biodegradability (%) = [(Number of moles of carbon of plant-derived monomers when calculating the molar ratio of each component with the molar ratio of carboxy groups and hydroxyl groups being 1:1 from the molar ratio of the charged amounts of polycarboxylic acids (a) and polyol components (b)) / (Number of moles of carbon of all constituent monomers)] × 100 <In the case not involving polycondensation reaction> Biodegradability (%) = [(Charged number of moles of carbon of plant-derived monomers) / (Number of moles of carbon of all constituent monomers)] × 100

[0082] Also, the above biodegradability can also be determined by analyzing the composition ratio of the resin by NMR and calculating the number of carbon atoms of the plant-derived monomers / the total number of carbon atoms.

[0083] Furthermore, the above biodegradability can also be measured by a method according to "ASTM D-6866" [Measurement of natural radioactive carbon (C-14) concentration].

[0084] The heat of crystal melting measured by a differential scanning calorimeter (DSC) for polyester resins (i) and (ii) is preferably 10 J / g or less, more preferably 5 J / g or less, still more preferably 2 J / g or less, and particularly preferably no heat of crystal melting. If such heat of crystal melting is too large, crystallinity will occur, and the storage stability of the resin solution will tend to be poor, and the stability and adhesion characteristics at low temperatures when made into an adhesive sheet will tend to be poor.

[0085] As a method for adjusting the above-mentioned heat of crystal fusion within a predetermined range, for example, a method of appropriately using polyvalent carboxylic acids having an alkyl group in the side chain or polyol components having an alkyl group in the side chain, a method of using three or more copolymer monomer components, preferably four or more components, etc. can be mentioned.

[0086] The above-mentioned heat of crystal fusion refers to the energy consumed when a crystallized substance is heated and melted, and can be measured by a differential scanning calorimeter (DSC).

[0087] The weight average molecular weight of the above polyester resins (i) and (ii) is preferably 2,000 to 500,000, more preferably 10,000 to 300,000, and particularly preferably 50,000 to 150,000. If the weight average molecular weight is too large, the handleability decreases, so a large amount of solvent is required, and the environmental load tends to increase. If the weight average molecular weight is too small, the adhesive physical properties tend to decrease.

[0088] The above-mentioned weight average molecular weight is the weight average molecular weight in terms of standard polystyrene molecular weight, and is measured by using two columns of TSKgel SuperMultipore HZ-M (exclusion limit molecular weight: 2×10 6 , theoretical plate number: 16,000 plates / book, filler material: styrene-divinylbenzene copolymer, filler particle size: 4 μm) in series.

[0089] The acid value of the above polyester resins (i) and (ii) is preferably 10 mgKOH / g or less in terms of preventing hydrolysis and improving durability, more preferably 5 mgKOH / g or less, particularly preferably 2 mgKOH / g or less, and especially preferably 1 mgKOH / g or less. If such an acid value is too large, the durability tends to decrease. To adjust the above acid value, for example, increasing the ratio of the polyol component (b) or adjusting the reaction conditions during the esterification reaction or transesterification reaction can be mentioned. The lower limit value of the acid value is usually 0 mgKOH / g.

[0090] The acid values of the above polyester resins (i) and (ii) are determined by neutralization titration based on JIS K0070. Note that the acid value in the present invention means the content of carboxy groups in the polyester resins (i) and (ii). The above carboxy groups include those in the carboxylate ion state in which the carboxy group is neutralized by a basic compound.

[0091] The glass transition temperature (Tg) of the above polyester resins (i) and (ii) is preferably -90 to 20°C, particularly preferably -80 to 0°C, more preferably -60 to -20°C, and especially preferably -50 to -30°C. If the glass transition temperature (Tg) is too high, the adhesion of the resulting pressure-sensitive adhesive composition tends to decrease. If it is too low, the heat resistance and the cohesive force tend to decrease. To adjust the above glass transition temperature, for example, introducing an aromatic skeleton or changing the alkyl chain length of the polyvalent carboxylic acid component or glycol component can be mentioned.

[0092] The above glass transition temperature (Tg) is measured using a differential scanning calorimeter DSC Q20 manufactured by TA Instruments. The measurement temperature range is -90 to 100°C, and the temperature increase rate is 10°C / min.

[0093] In the pressure-sensitive adhesive composition of the present invention, together with the above polyester resin (i) or (ii), for example, a hydrolysis inhibitor (iii), a crosslinking agent (iv), a urethanization catalyst (v), an antioxidant (vi), a tackifier resin (vii), etc. are preferably contained.

[0094] <Hydrolysis inhibitor (iii)> The above hydrolysis inhibitor (iii) is contained to ensure long-term durability. As the hydrolysis inhibitor (iii) described above, conventionally known ones can be used. For example, compounds that react and bond with the carboxy group terminals of the polyester resins (i) and (ii) are included. Specifically, for example, compounds containing functional groups such as a carbodiimide group, an epoxy group, an oxazoline group, etc. are included. Among these, carbodiimide group-containing compounds are preferable in that they have a high effect of eliminating the catalytic activity of protons derived from the carboxy group terminals.

[0095] As the carbodiimide group-containing compound described above, usually, known carbodiimides having one or more carbodiimide groups (-N=C=N-) in the molecule can be used. However, in terms of improving durability under higher temperature and humidity conditions, a compound containing two or more carbodiimide groups in the molecule, that is, a polyvalent carbodiimide-based compound is preferable, and particularly, a compound containing three or more, further five or more, especially seven or more carbodiimide groups in the molecule is preferable. Note that the number of carbodiimide groups in the molecule is usually 50 or less. If there are too many carbodiimide groups, the molecular structure becomes too large, and thus the compatibility tends to decrease. It is also preferable to use a high molecular weight polycarbodiimide produced by subjecting a diisocyanate to a decarboxylation condensation reaction in the presence of a carbodiimidization catalyst.

[0096] Furthermore, a high molecular weight polycarbodiimide in which the terminal isocyanate groups are blocked by a blocking agent is preferable in terms of storage stability. Examples of the blocking agent include compounds having active hydrogen that reacts with an isocyanate group, or compounds having an isocyanate group. For example, monoalcohols, monocarboxylic acids, monoamines, and monoisocyanates having one substituent selected from a carboxy group, an amino group, and an isocyanate group are included.

[0097] Examples of such high molecular weight polycarbodiimides include those obtained by subjecting the following diisocyanates to a decarboxylation condensation reaction.

[0098] Examples of such diisocyanates include 4,4'-diphenylmethane diisocyanate, 3,3'-dimethoxy-4,4'-diphenylmethane diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, 3,3'-dimethyl-4,4'-diphenyl ether diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1-methoxyphenyl-2,4-diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, tetramethylxylylene diisocyanate, etc. These can be used alone or in combination of two or more. Such high molecular weight polycarbodiimides may be synthesized or commercially available products may be used.

[0099] Examples of commercially available products of the carbodiimide group-containing compound include, for example, the Carbodilite (registered trademark) series manufactured by Nisshinbo Chemical Inc. Among them, Carbodilite (registered trademark) "V-01", "V-02B", "V-03", "V-04K", "V-04PF", "V-05", "V-07", "V-09", "V-09GB" are preferable in terms of excellent compatibility with organic solvents.

[0100] Examples of the epoxy group-containing compound include, for example, glycidyl ester compounds and glycidyl ether compounds, etc.

[0101] Specific examples of the glycidyl ester compound include, for example, glycidyl benzoate, glycidyl t-Bu-benzoate, glycidyl p-toluate, glycidyl cyclohexanecarboxylate, glycidyl pelargonate, glycidyl stearate, glycidyl laurate, glycidyl palmitate, glycidyl behenate, glycidyl versatate, glycidyl oleate, glycidyl linoleate, glycidyl linolenate, glycidyl behenolate, glycidyl stearolate, diglycidyl terephthalate, diglycidyl isophthalate, diglycidyl phthalate, diglycidyl naphthalenedicarboxylate, diglycidyl methyl terephthalate, diglycidyl hexahydrophthalate, diglycidyl tetrahydrophthalate, diglycidyl cyclohexanedicarboxylate, diglycidyl adipate, diglycidyl succinate, diglycidyl sebacate, diglycidyl dodecanedioate, diglycidyl octadecanedicarboxylate, triglycidyl trimellitate, tetraglycidyl pyromellitate, etc. These can be used alone or in combination of two or more kinds.

[0102] Specific examples of the glycidyl ether compound include, for example, phenyl glycidyl ether, o-phenyl glycidyl ether, 1,4-bis(β,γ-epoxypropoxy)butane, 1,6-bis(β,γ-epoxypropoxy)hexane, 1,4-bis(β,γ-epoxypropoxy)benzene, 1-(β,γ-epoxypropoxy)-2-ethoxyethane, 1-(β,γ-epoxypropoxy)-2-benzyloxyethane, 2,2-bis-[p-(β,γ-epoxypropoxy)phenyl]propane and bisphenols such as 2,2-bis-(4-hydroxyphenyl)propane and 2,2-bis-(4-hydroxyphenyl)methane and bisglycidyl polyethers obtained by the reaction of epichlorohydrin, etc. These can be used alone or in combination of two or more kinds.

[0103] As the oxazoline group-containing compound, bisoxazoline compounds and the like are preferable. Specifically, for example, 2,2'-bis(2-oxazoline), 2,2'-bis(4-methyl-2-oxazoline), 2,2'-bis(4,4-dimethyl-2-oxazoline), 2,2'-bis(4-ethyl-2-oxazoline), 2,2'-bis(4,4'-diethyl-2-oxazoline), 2,2'-bis(4-propyl-2-oxazoline), 2,2'-bis(4-butyl-2-oxazoline), 2,2'-bis(4-hexyl-2-oxazoline), 2,2'-bis(4-phenyl-2-oxazoline), 2,2'-bis(4-cyclohexyl-2-oxazoline), 2,2'-bis(4-benzyl-2-oxazoline), 2,2'-p-phenylene bis(2-oxazoline), 2,2'-m-phenylene bis(2-oxazoline), 2,2'-o-phenylene bis(2-oxazoline), 2,2'-p-phenylene bis(4-methyl-2-oxazoline), 2,2'-p-phenylene bis(4,4-dimethyl-2-oxazoline), 2,2'-m-phenylene bis(4-methyl-2-oxazoline), 2,2'-m-phenylene bis(4,4-dimethyl-2-oxazoline), 2,2'-ethylene bis(2-oxazoline), 2,2'-tetramethylene bis(2-oxazoline), 2,2'-hexamethylene bis(2-oxazoline), 2,2'-octamethylene bis(2-oxazoline), 2,2'-decamethylene bis(2-oxazoline), 2,2'-ethylene bis(4-methyl-2-oxazoline), 2,2'-tetramethylene bis(4,4-dimethyl-2-oxazoline), 2,2'-9,9'-diphenoxyethane bis(2-oxazoline), 2,2'-cyclohexylene bis(2-oxazoline), 2,2'-diphenylene bis(2-oxazoline) and the like can be exemplified. Among these, 2,2'-bis(2-oxazoline) is most preferable from the viewpoint of reactivity with the polyester resins (i) and (ii). Further, these can be used alone or in combination of two or more.

[0104] As these hydrolysis inhibitors (iii), those with lower volatility are preferred, and for this purpose, those with a higher number average molecular weight are preferably used. Usually, the number average molecular weight is 300 to 10,000, preferably 1,000 to 5,000.

[0105] Also, as the hydrolysis inhibitor (iii), those with a higher weight average molecular weight are preferably used from the viewpoint of hydrolysis resistance. The weight average molecular weight of the hydrolysis inhibitor (iii) is preferably 500 or more, more preferably 2,000 or more, and even more preferably 3,000 or more. The upper limit of the weight average molecular weight is usually 50,000.

[0106] If the molecular weight of the hydrolysis inhibitor (iii) is too small, the hydrolysis resistance tends to decrease. If the molecular weight is too large, the compatibility with the polyester resins (i) and (ii) tends to decrease.

[0107] Among these hydrolysis inhibitors (iii), it is preferable to use a carbodiimide group-containing compound. In this case, the carbodiimide equivalent is preferably 50 to 10,000, particularly 100 to 1,000, and even more preferably 150 to 500. The carbodiimide equivalent indicates the chemical formula weight per one carbodiimide group.

[0108] The content of the above hydrolysis inhibitor (iii) is preferably 0.01 to 10 parts by weight, particularly preferably 0.1 to 5 parts by weight, and even more preferably 0.2 to 3 parts by weight with respect to 100 parts by weight of the above polyester resin (i) or (ii). If such a content is too much, turbidity tends to occur due to poor compatibility with the polyester resin (i) or (ii), and if it is too little, sufficient durability tends to be difficult to obtain.

[0109] In addition, the content of the hydrolysis inhibitor (iii) is preferably optimized according to the acid value of the polyester resin (i) or (ii). The molar ratio [(y) / (x)] of the total number of moles (y) of the functional groups of the hydrolysis inhibitor (iii) in the pressure-sensitive adhesive composition to the total number of moles (x) of the acidic functional groups of the polyester resin (i) or (ii) in the pressure-sensitive adhesive composition is preferably 0.5 ≦ (y) / (x), particularly preferably 1 ≦ (y) / (x) ≦ 1000, and more preferably 1.5 ≦ (y) / (x) ≦ 100. When the molar ratio of (y) to (x) is too low, the hygrothermal performance tends to deteriorate. When the molar ratio of (y) to (x) is too high, the compatibility with the polyester resin (i) or (ii) tends to decrease, and the adhesive strength, cohesive force, and durability performance tend to decrease.

[0110] <Crosslinking agent (iv)> The pressure-sensitive adhesive composition in the present invention preferably further contains a crosslinking agent (iv). By containing the crosslinking agent (iv), the polyester resin (i) or (ii) is crosslinked with the crosslinking agent (iv) to have excellent cohesive force, and the performance as a pressure-sensitive adhesive can be improved.

[0111] Examples of such a crosslinking agent (iv) include compounds having a functional group that reacts with at least one of the hydroxyl group and the carboxyl group contained in the polyester resins (i) and (ii), such as polyisocyanate-based compounds and polyepoxy-based compounds. In addition, polyfunctional acrylic monomers and urethane acrylate oligomers that can increase the cohesive force even if they do not react with the polyester resins (i) and (ii) can also be used. Among these, it is particularly preferable to use polyisocyanate-based compounds from the viewpoint of achieving a good balance between initial adhesiveness, mechanical strength, and heat resistance.

[0112] Examples of such polyisocyanate compounds include polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, tetramethylxylylene diisocyanate, 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate, etc. Further, adducts of the above polyisocyanates and polyol compounds such as trimethylolpropane, and burette bodies, isocyanurate bodies, etc. of these polyisocyanate compounds are included. In addition, the above polyisocyanate compounds in which the isocyanate moiety is blocked with phenol, lactam, etc. can also be used. These crosslinking agents (iv) may be used alone or in combination of two or more.

[0113] The content of such a crosslinking agent (iv) can be appropriately selected according to the molecular weights and intended uses of the polyester resins (i) and (ii). Usually, the reactive groups contained in the crosslinking agent (iv) are preferably contained in the crosslinking agent (iv) at a ratio of 0.2 to 10 equivalents per 1 equivalent of at least one of the hydroxyl groups and carboxyl groups contained in the polyester resin (i) or (ii). Particularly preferably, it is 0.5 to 5 equivalents, and more preferably 0.5 to 3 equivalents. If the equivalent number of the reactive groups contained in such a crosslinking agent (iv) is too small, the cohesive force tends to decrease, and if it is too large, the flexibility tends to decrease.

[0114] In addition, the content of such a crosslinking agent (iv) is preferably 0.01 to 10 parts by weight, particularly preferably 0.1 to 8 parts by weight, further preferably 0.5 to 6 parts by weight, and especially preferably 1 to 4 parts by weight with respect to 100 parts by weight of the polyester resin (i) or (ii). If there is too little of such a crosslinking agent, the cohesive force tends to decrease, and if it is too large, the flexibility decreases and the required adhesive force tends not to be obtained.

[0115] In the reaction of the polyester resins (i) and (ii) with the crosslinking agent (iv), organic solvents having no functional groups that react with these components (i), (ii), and (iv), such as esters like ethyl acetate and butyl acetate, ketones like methyl ethyl ketone and methyl isobutyl ketone, and aromatics like toluene and xylene, can be used. These can be used alone or in combination of two or more.

[0116] <Urethane-forming catalyst (v)> In view of the reaction rate, it is more preferable for the pressure-sensitive adhesive composition of the present invention to contain a urethane-forming catalyst (v).

[0117] Examples of the urethane-forming catalyst (v) include organometallic compounds and tertiary amine compounds. These can be used alone or in combination of two or more.

[0118] Examples of the above-mentioned organometallic compounds include zirconium compounds, iron compounds, tin compounds, titanium compounds, lead compounds, cobalt compounds, zinc compounds, etc. Examples of zirconium compounds include zirconium naphthenate and zirconium acetylacetonate. Examples of iron compounds include iron acetylacetonate and iron 2-ethylhexanoate. Examples of tin compounds include dibutyltin dichloride, dibutyltin oxide, dibutyltin dilaurate, etc.

[0119] Examples of titanium compounds include dibutyltitanium dichloride, tetrabutyl titanate, butoxytitanium trichloride, etc. Examples of lead compounds include lead oleate, lead 2-ethylhexanoate, lead benzoate, lead naphthenate, etc. Examples of cobalt compounds include cobalt 2-ethylhexanoate and cobalt benzoate. Examples of the zinc-based compound include zinc naphthenate, zinc 2-ethylhexanoate, and the like. Examples of the tertiary amine compound include triethylamine, triethylenediamine, 1,8-diazabicyclo-(5,4,0)-undecene-7, and the like.

[0120] Among these urethanization catalysts (v), organometallic compounds are preferable, and zirconium-based compounds are particularly preferable, in terms of reaction rate and pot life of the adhesive layer. Further, it is preferable to use acetylacetone in combination with the urethanization catalyst (v) as a catalyst action inhibitor. Inclusion of acetylacetone is preferable in that it suppresses the catalytic action at low temperatures and lengthens the pot life.

[0121] The content of the urethanization catalyst (v) is preferably 0.0001 to 1 part by weight, particularly preferably 0.001 to 0.1 part by weight, and still more preferably 0.01 to 0.05 part by weight, based on 100 parts by weight of the polyester resin (i) or (ii). If the content is too small, the aging time until the crosslinking reaction is completed tends to be long, and if it is too large, the adhesive physical properties tend to deteriorate.

[0122] <Antioxidant (vi)> The adhesive composition of the present invention more preferably contains an antioxidant (vi) from the viewpoint of improving the stability of the resin.

[0123] Examples of the antioxidant (vi) 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 hindered phenol-based antioxidants, amine-based antioxidants, and phosphoric acid-based antioxidants is preferable, and an antioxidant composed of a hindered phenol-based compound is particularly preferable. Examples of the hindered phenol antioxidant include antioxidants having a hindered phenol structure in which a group with a large steric hindrance such as a tertiary butyl group is bonded to at least one of the adjacent carbon atoms of the carbon atom on the aromatic ring to which the hydroxyl group of phenol is bonded.

[0124] The content of the antioxidant (vi) 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 5 parts by weight with respect to 100 parts by weight of the polyester resin (i) or (ii). If such a content is too small, there is a tendency that glue residue on the adherend is likely to occur, and if it is too large, there is a tendency that the adhesive physical properties decrease.

[0125] <Adhesion - imparting resin (vii)> In the present invention, it is preferable to contain the adhesion - imparting resin (vii) in terms of being able to improve the adhesion characteristics.

[0126] The adhesion - imparting resin (vii) is not particularly limited, and conventionally known ones can be used. Examples of the adhesion - imparting resin (vii) include hydrocarbon - based adhesion - imparting resins, terpene - based resins, phenol - based resins, rosin - based resins, xylene resins, epoxy - based resins, polyamide - based resins, ketone - based resins, elastomer - based resins, etc. These may be used alone or in combination of two or more. Among them, hydrocarbon - based adhesion - imparting resins, terpene - based resins, and rosin - based resins are preferable in terms of improving the adhesive physical properties. Also, it is particularly preferable that the adhesion - imparting resin (vii) contains at least one of a hydrocarbon - based adhesion - imparting resin and a terpene - based resin from the viewpoint of the stability of the adhesive. Furthermore, a terpene - based resin is particularly preferable in terms of maintaining a high degree of biodegradability and being compatible with physical properties. The content thereof is preferably 30% by weight or more, preferably 50% by weight or more, and preferably 70% by weight or more of the total adhesion - imparting resin.

[0127] Examples of the hydrocarbon-based tackifying resin include various hydrocarbon-based resins such as aliphatic hydrocarbon resins, aromatic hydrocarbon resins, aliphatic cyclic hydrocarbon resins, aliphatic-aromatic petroleum resins (such as styrene-olefin copolymers), aliphatic-alicyclic petroleum resins, hydrogenated hydrocarbon resins, coumarone resins, and coumarone-indene resins. Examples of commercially available products include "FTR6100", "FTR6110", "FTR6125", etc. manufactured by Mitsui Chemicals, Inc.

[0128] Examples of the terpene-based resin include terpene resins, terpene phenol resins, and aromatic-modified terpene resins. Specifically, α-pinene polymers, β-pinene polymers, dipentene polymers, and terpene-based resins obtained by phenol modification, aromatic modification, hydrogenation modification, or hydrocarbon modification of these can be used. Among them, terpene resins are preferable in that the adhesive strength after 24 hours of sticking tends to be high, and terpene phenol resins are preferable in that the adhesive strength to olefins is high. Examples of commercially available products include "YS Polyster S145", "YS Resin PX1000", "YS Resin PX1250", "YS Polyster T145", "YS Resin TO115", "YS Polyster U130", "Clearon P125", etc. manufactured by Yasuhara Chemical Co., Ltd.

[0129] Examples of the phenolic resin that can be used include condensates of various phenols such as phenol, m-cresol, 3,5-xylenol, p-alkylphenol, and resorcinol with formaldehyde. Furthermore, resol obtained by subjecting the phenols and formaldehyde to an addition reaction under an alkaline catalyst, novolak obtained by subjecting the phenols and formaldehyde to a condensation reaction under an acid catalyst, rosin-modified phenolic resins obtained by adding phenol to unmodified or modified rosin or derivatives thereof such as these under an acid catalyst and then thermally polymerizing, etc. can be used.

[0130] Examples of the rosin-based resin include rosin resin, polymerized rosin resin, hydrogenated rosin resin, rosin ester resin, hydrogenated rosin ester resin, rosin phenol resin, polymerized rosin ester, etc. Specifically, unmodified rosin (raw rosin) such as gum rosin, wood rosin, and tall oil rosin, modified rosin obtained by hydrogenating, disproportionating, polymerizing, or other chemically modifying these, and derivatives thereof can be used. Examples of commercially available products include "Halister TF", "Halitack 8LJA", "Halitack PH", "Halitack FK100", "Halitack PCJ", etc. manufactured by Harima Kasei Co., Ltd.

[0131] The tackifier resin (vii) preferably has an acid value of 30 mgKOH / g or less, particularly preferably 10 mgKOH / g or less, more preferably 3 mgKOH / g or less, and especially preferably 1 mgKOH / g or less. When using a combination of multiple types of tackifier resins, the average preferably falls within the above range.

[0132] The softening point of the tackifier resin (vii) (measured by, for example, the ring and ball method) is preferably 80 to 170°C, particularly preferably 85 to 160°C, and more preferably 95 to 150°C. When the softening point is within the above range, the tackiness characteristics (adhesive force, cohesive force) can be improved, which is preferable.

[0133] In the present invention, the tackifier resin (vii) is preferably of plant origin in order to keep the bioplastic degree of the entire adhesive high. Examples of the plant-derived tackifier resin include terpene-based resins, rosin-based resins, etc.

[0134] The content of the tackifier resin (vii) is preferably 2 to 100 parts by weight, more preferably 5 to 80 parts by weight, still more preferably 6 to 50 parts by weight, particularly preferably 8 to 30 parts by weight, and especially preferably 9 to 20 parts by weight, based on 100 parts by weight of the polyester resin (i) or (ii). If the content is too much, the adhesive layer tends to become too hard and the adhesion tends to decrease. If the content is too little, it tends to be difficult to obtain the additive effect.

[0135] In the adhesive composition of the present invention, in addition to the above polyester resin (i) or (ii), hydrolysis inhibitor (iii), crosslinking agent (iv), urethanization catalyst (v), antioxidant (vi), and tackifier resin (vii), additives such as softeners, ultraviolet absorbers, stabilizers, antistatic agents, etc., and other inorganic or organic fillers, powders such as metal powders and pigments, and particulate additives can be blended within the range that does not impair the effects of the present invention. Also, it may contain a small amount of impurities contained in the raw materials for producing the components of the adhesive. These can be used alone or in combination of two or more.

[0136] Also, the adhesive of the present invention is obtained by crosslinking the above adhesive composition. Furthermore, the adhesive of the present invention preferably has a bioplasticity degree of 60% or more, more preferably 65% or more, still more preferably 70% or more, and particularly preferably 80% or more. The bioplasticity degree of the above adhesive can be adjusted by adjusting the types and blending amounts of the polyester resins (i), (ii) and other blending components. The bioplasticity degree of the above adhesive can be obtained by considering the bioplasticity degree of the polyester resin determined by the above method and the ratio of bio-derived carbon for each other component and calculating the weighted average.

[0137] In addition, the bio-plasticity degree of the above-mentioned adhesive can also be measured by the method using the aforementioned NMR or a method in accordance with ASTM D-6866 [Measurement of Natural Radioactive Carbon (C-14) Concentration].

[0138] And the adhesive of the present invention is an adhesive in which the adhesive composition is crosslinked, and the adhesive force (α) under the following conditions is 1 N / 25 mm or more, more preferably 5 to 100 N / 25 mm, still more preferably 7 to 50 N / 25 mm, and particularly preferably 9 to 30 N / 25 mm. If the above adhesive force is too small, the adhesion reliability will decrease. Adhesive force (α): When the adhesive layer composed of the adhesive forms an adhesive sheet on the base material, after being attached to the adherend of SUS-BA plate and left standing for 30 minutes in an environment of 23°C and 50% RH, the 180-degree peel strength (N / 25 mm) at a peel rate of 300 mm / min with respect to the adherend.

[0139] And the adhesive sheet of the present invention has an adhesive layer containing the above-mentioned adhesive, and it is preferable that such an adhesive layer is formed on one or both sides of the support base material. In the present invention, "sheet" is described as meaning including "film" and "tape".

[0140] <Adhesive sheet> The adhesive sheet can be produced, for example, as follows. As a manufacturing method of such an adhesive sheet, it can be manufactured according to a known general manufacturing method of an adhesive sheet. For example, on the base material, the above-mentioned adhesive composition is coated and dried, a release sheet is laminated on the opposite adhesive composition layer surface, and if necessary, cured to obtain the adhesive sheet of the present invention having an adhesive layer containing an adhesive on the base material.

[0141] Also, by coating and drying the above-mentioned adhesive composition on the release sheet, laminating the base material on the opposite adhesive composition layer surface, and if necessary, curing, the adhesive sheet of the present invention can also be obtained.

[0142] In addition, a substrate-free double-sided adhesive sheet can be manufactured by forming an adhesive layer on a release sheet and laminating a release sheet on the adhesive layer surface on the opposite side.

[0143] When using the obtained adhesive sheet or substrate-free double-sided adhesive sheet, during use, the above release sheet is peeled off from the adhesive layer and the adhesive layer is bonded to the adherend.

[0144] Examples of the above substrate include polyester resins such as polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate, and polyethylene terephthalate / isophthalate copolymer; polyolefin resins such as polyethylene, polypropylene, and polymethylpentene; polyfluoroethylene resins such as polyvinyl fluoride, polyvinylidene fluoride, and polyfluoroethylene; polyamides such as nylon 6 and nylon 6,6; vinyl polymers such as polyvinyl chloride, polyvinyl chloride / vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, and vinylon; cellulose resins such as triacetate cellulose and cellophane; acrylic resins such as polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, and polybutyl acrylate; polystyrene; polycarbonate; polyarylate; polyimide; and sheets made of at least one synthetic resin selected from the group consisting of cycloolefin polymers; metal foils of aluminum, copper, and iron; papers such as high-quality paper and glassine paper; and woven fabrics and non-woven fabrics made of glass fibers, natural fibers, synthetic fibers, etc. These substrates can be used as a single layer or as a multilayer in which two or more layers are laminated.

[0145] Among these, substrates made of polyethylene terephthalate and polyimide are particularly preferred, and polyethylene terephthalate is particularly preferred in terms of excellent adhesiveness to the adhesive.

[0146] Further, as the base material, a foam sheet made of a foam of a synthetic resin such as a foam base material, for example, a polyurethane foam, a polyethylene foam, a polyacrylate foam, etc. can be used. Among these, a polyethylene foam and a polyacrylate foam are preferable in terms of excellent followability to the adherend and balance of adhesive strength.

[0147] The thickness of the above base material is preferably, for example, 1 to 1000 μm, particularly preferably 2 to 500 μm, and even more preferably 3 to 300 μm.

[0148] As the release sheet, for example, a sheet made of various synthetic resins exemplified for the above base material, paper, cloth, a non-woven fabric, etc. subjected to a release treatment can be used. As the release sheet, a silicone-based release sheet is preferably used.

[0149] As the coating method of the above pressure-sensitive adhesive composition, 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. may be used.

[0150] As the conditions of the above curing treatment, the temperature is usually room temperature (23 ° C) to 70 ° C, and the time is usually 1 to 30 days. Specifically, for example, it may be carried out under conditions such as 1 to 20 days at 23 ° C, preferably 3 to 14 days at 23 ° C, 1 to 10 days at 40 ° C, etc.

[0151] Further, as the drying conditions, the drying temperature is preferably 60 to 140 ° C, particularly preferably 80 to 120 ° C, and the drying time is preferably 0.5 to 30 minutes, particularly preferably 1 to 5 minutes.

[0152] The thickness of the adhesive layer of the above-mentioned adhesive sheet and the substrate-free double-sided adhesive sheet is preferably 2 to 500 μm, particularly preferably 5 to 200 μm, and even more preferably 10 to 100 μm. If the thickness of such an adhesive layer is too thin, the adhesive strength tends to decrease. If it is too thick, it becomes difficult to apply it uniformly, and there is a tendency that problems such as air bubbles entering the coating film are likely to occur. In addition, when considering impact absorbency, it is preferably 50 μm or more.

[0153] The thickness of the above-mentioned adhesive layer is determined by subtracting the measured value of the thickness of the constituent members other than the adhesive layer from the measured value of the thickness of the entire adhesive sheet using "ID-C112B" manufactured by Mitutoyo Corporation.

[0154] Regarding the gel fraction of the adhesive layer of the above-mentioned adhesive sheet, from the viewpoints of durability performance and adhesive strength, it is preferably 10% by weight or more, particularly preferably 20 to 80% by weight, even more preferably 25 to 70% by weight, and particularly preferably 27 to 45% by weight. If the gel fraction is too low, the cohesive force decreases, and thus the holding force tends to decrease. If the gel fraction is too high, the adhesive strength tends to decrease due to the increase in the cohesive force.

[0155] The above-mentioned gel fraction serves as a measure of the degree of crosslinking and is calculated, for example, by the following method. That is, an adhesive sheet (one without a release sheet) in which an adhesive layer is formed on a polymer sheet serving as a substrate (for example, a PET film, etc.) is wrapped with a 200-mesh SUS wire mesh and immersed in toluene at 23 °C for 24 hours. The weight percentage of the insoluble adhesive component remaining in the wire mesh after immersion with respect to the weight of the adhesive component before immersion is defined as the gel fraction. However, the weight of the substrate is subtracted.

[0156] Furthermore, such an adhesive sheet may be provided with a release sheet on the outside of the adhesive layer for protection as needed. Also, in the case of an adhesive sheet in which the adhesive layer is formed on one side of the substrate, it is also possible to protect the adhesive layer by performing a peeling treatment on the surface of the substrate opposite to the adhesive layer and using the peeled surface.

[0157] The pressure-sensitive adhesive of the present invention can be used for bonding various members, and in particular, a single-sided or double-sided adhesive sheet used for bonding optical members, a single-sided or double-sided adhesive sheet used for fixing members of a portable electronic device or fixing electronic members, etc.

Examples

[0158] Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the examples, "parts" and "%" mean weight basis.

[0159] Regarding the measurement of the biodegradable degree, ester group concentration, heat of crystal melting, weight average molecular weight, glass transition temperature, acid value, and gel fraction of the pressure-sensitive adhesive of the polyester resin in the following examples, the measurement was carried out according to the above-described method.

[0160] A polyester resin was produced by the following method.

[0161] 〔Production Example 1: Production of polyester resin (i-1)〕 Into a reaction vessel equipped with a thermometer, a stirrer, a rectification column, a nitrogen inlet tube, and a vacuum device, 17.8 parts (0.45 mol) of sebacic acid, 61.4 parts (0.55 mol) of hydrogenated distilled dimer acid (manufactured by Kuraray Co., Ltd., "Pripol 1009") as polyvalent carboxylic acids (a), 20.7 parts (1.7 mol) of ethylene glycol and 0.2 parts (0.0065 mol) of trimethylolpropane as a polyol component (b), and 0.01 part of tetrabutyl titanate as a catalyst were charged. The temperature was gradually raised to 250 ° C, and an esterification reaction was carried out over 4 hours. Then, the internal temperature was raised to 260 ° C, 0.01 part of tetrabutyl titanate was charged as a catalyst, the pressure was reduced to 1.33 hPa, and a polymerization reaction was carried out over 3 hours to produce a polyester resin (i-1). The biodegradable degree of the obtained polyester resin (i-1) was 92%, the ester group concentration was 4.64 mmol / g, the heat of crystal melting was 0 J / g, the weight average molecular weight was 58,000, the glass transition temperature (Tg) was -50 ° C, and the acid value was 0.4 mgKOH / g. The plant-derived raw materials in Production Example 1 were sebacic acid and hydrogenated distilled dimer acid, and the content thereof with respect to the polyester resin (i-1) was 86%.

[0162] 〔Production Example 2: Production of polyester resin (i-2)〕 Into a reaction vessel equipped with a thermometer, a stirrer, a rectifying column, a nitrogen inlet tube, and a vacuum device, 84.3 parts (1.00 mol) of hydrogenated distilled dimer acid (manufactured by Croda, "Pripol 1009") as the polycarboxylic acids (a), 15.6 parts (1.7 mol) of ethylene glycol and 0.1 part (0.0065 mol) of trimethylolpropane as the polyol component (b), and 0.01 part of tetrabutyl titanate as the catalyst were charged. The temperature was gradually raised to 250°C, and an esterification reaction was carried out over 4 hours. Thereafter, the internal temperature was raised to 260°C, 0.01 part of tetrabutyl titanate was charged as the catalyst, the pressure was reduced to 1.33 hPa, and a polymerization reaction was carried out over 3 hours to produce a polyester resin (i-2). The bioplastic degree of the obtained polyester resin (i-2) was 95%, the ester group concentration was 3.36 mmol / g, the crystal melting heat was 0 J / g, the weight average molecular weight was 72,000, the glass transition temperature (Tg) was -47°C, and the acid value was 0.3 mgKOH / g. The plant-derived raw material in Production Example 2 was hydrogenated distilled dimer acid, and the content thereof with respect to the polyester resin (i-2) was 90%.

[0163] 〔Production Example 3: Production of polyester resin (i-3)〕 Into a reaction vessel equipped with a thermometer, a stirrer, a rectification column, a nitrogen inlet tube, and a vacuum device, 80.6 parts (1.00 mol) of hydrogenated distilled dimer acid (manufactured by Croda, "Pripol 1009") as polycarboxylic acids (a), 19.1 parts (1.5 mol) of 1,4-butanediol and 0.3 parts (0.015 mol) of trimethylolpropane as polyol component (b), and 0.01 part of tetrabutyl titanate as a catalyst were charged. The temperature was gradually raised to 250 °C, and an esterification reaction was carried out over 4 hours. Then, the internal temperature was raised to 260 °C, 0.01 part of tetrabutyl titanate was charged as a catalyst, the pressure was reduced to 1.33 hPa, and a polymerization reaction was carried out over 3 hours to produce a polyester resin (i-3). The bioplastic degree of the obtained polyester resin (i-3) was 86%, the ester group concentration was 3.21 mmol / g, the heat of crystal fusion was 0 J / g, the weight average molecular weight was 71,000, the glass transition temperature (Tg) was -52 °C, and the acid value was 0.3 mgKOH / g. In addition, the plant-derived raw material in Production Example 3 was hydrogenated distilled dimer acid, and its content in the polyester resin (i-3) was 86%.

[0164] [Production Example 4: Production of polyester resin (i-4)] Into a reaction vessel equipped with a thermometer, a stirrer, a rectification column, a nitrogen inlet tube, and a vacuum device, 80.3 parts (1.00 mol) of hydrogenated distilled dimer acid (manufactured by Croda, "Pripol 1009") as polycarboxylic acids (a), 7.9 parts (0.90 mol) of ethylene glycol, 11.7 parts (0.80 mol) of neopentyl glycol and 0.1 parts (0.0065 mol) of trimethylolpropane as polyol component (b), and 0.01 part of tetrabutyl titanate as a catalyst were charged. The temperature was gradually raised to 250 °C, and an esterification reaction was carried out over 4 hours. Then, the internal temperature was raised to 260 °C, 0.01 part of tetrabutyl titanate was charged as a catalyst, the pressure was reduced to 1.33 hPa, and a polymerization reaction was carried out over 3 hours to produce a polyester resin (i-4). The bioplastic degree of the obtained polyester resin (i-4) was 91%, the ester group concentration was 3.25 mmol / g, the heat of crystal fusion was 0 J / g, the weight average molecular weight was 72,000, the glass transition temperature (Tg) was -47 °C, and the acid value was 0.2 mgKOH / g. Incidentally, the plant-derived raw material in Production Example 4 was hydrogenated distilled dimer acid, and its content with respect to the polyester resin (i-4) was 87%.

[0165] 〔Production Example 5: Production of polyester resin (i-5)〕 Into a reaction vessel equipped with a thermometer, a stirrer, a rectifying column, a nitrogen inlet tube, and a vacuum device, 17.0 parts (0.45 mol) of sebacic acid, 58.5 parts (0.55 mol) of hydrogenated distilled dimer acid (manufactured by Croda, "Pripol 1009") as polycarboxylic acids (a), 24.3 parts (2.1 mol) of ethylene glycol and 0.2 part (0.0065 mol) of trimethylolpropane as polyol component (b), and 0.01 part of tetrabutyl titanate as a catalyst were charged. The temperature was gradually raised to 250 °C, and an esterification reaction was carried out over 4 hours. Then, the internal temperature was raised to 260 °C, 0.01 part of tetrabutyl titanate was charged as a catalyst, the pressure was reduced to 1.33 hPa, and a polymerization reaction was carried out over 3 hours to produce a polyester resin (i-5). The bioplastic degree of the obtained polyester resin (i-5) was 92%, the ester group concentration was 4.64 mmol / g, the heat of crystal fusion was 0 J / g, the weight average molecular weight was 97,000, the glass transition temperature (Tg) was -50 °C, and the acid value was 0.1 mgKOH / g. Incidentally, the plant-derived raw materials in Production Example 5 were sebacic acid and hydrogenated distilled dimer acid, and their content with respect to the polyester resin (i-5) was 86%.

[0166] 〔Production Example 6: Production of polyester resin (i-6)〕 Into a reaction vessel equipped with a thermometer, a stirrer, a rectification column, a nitrogen inlet tube, and a vacuum device, 84.3 parts (1.00 mol) of hydrogenated distilled dimer acid (manufactured by Croda, "Pripol 1009") as polycarboxylic acids (a), 15.6 parts (1.7 mol) of ethylene glycol and 0.1 part (0.0065 mol) of trimethylolpropane as polyol component (b), and 0.01 part of tetrabutyl titanate as a catalyst were charged. The temperature was gradually raised to 250 °C, and an esterification reaction was carried out over 4 hours. Thereafter, the internal temperature was raised to 260 °C, 0.01 part of tetrabutyl titanate was charged as a catalyst, the pressure was reduced to 1.33 hPa, and a polymerization reaction was carried out over 3 hours to produce a polyester resin (i-6). The biodegradability of the obtained polyester resin (i-6) was 95%, the ester group concentration was 3.36 mmol / g, the heat of crystal fusion was 0 J / g, the weight average molecular weight was 88000, the glass transition temperature (Tg) was -47 °C, and the acid value was 0.1 mgKOH / g. In addition, the plant-derived raw material in Production Example 6 was hydrogenated distilled dimer acid, and its content in the polyester resin (i-6) was 90%.

[0167] 〔Comparative Production Example 1: Production of Polyester Resin (i'-1)〕 Into a reaction vessel equipped with a thermometer, a stirrer, a rectification column, a nitrogen inlet tube, and a vacuum device, 49.2 parts (1.00 mol) of hydrogenated distilled dimer acid (manufactured by Croda, "Pripol 1009") as polycarboxylic acids (a), 50.8 parts (1.09 mol) of dimer diol (manufactured by Croda, "Pripol 2033") as polyol component (b), and 0.01 part of tetrabutyl titanate as a catalyst were charged. The temperature was gradually raised to 200 °C, and an esterification reaction was carried out over 4 hours. Thereafter, the internal temperature was raised to 240 °C, 0.01 part of tetrabutyl titanate was charged as a catalyst, the pressure was reduced to 1.33 hPa, and a polymerization reaction was carried out over 3 hours to produce a polyester resin (i'-1). The bio-based plastic content of the obtained polyester resin (i'-1) was 100%, the ester group concentration was 1.78 mmol / g, the heat of crystal fusion was 0 J / g, the weight average molecular weight was 33,000, the glass transition temperature (Tg) was -50 °C, and the acid value was 0.1 mgKOH / g. The plant-derived raw materials in Comparative Production Example 1 were hydrogenated distilled dimer acid and dimer diol, and the content relative to the polyester resin (i'-1) was 100%.

[0168] 〔Comparative Production Example 2: Production of polyester resin (i'-2)〕 Into a reaction vessel equipped with a heating device, a thermometer, a stirrer, a rectification column, a nitrogen inlet tube, and a vacuum device, 9.6 parts (0.2 mol) of isophthalic acid and 46.8 parts (0.8 mol) of sebacic acid as polycarboxylic acids (a), 27.1 parts (0.900 mol) of neopentyl glycol, 13.0 parts (0.500 mol) of 1,4-butanediol, 3.0 parts (0.087 mol) of 1,6-hexanediol, and 0.5 part (0.013 mol) of trimethylolpropane as the polyol component (b), and 0.01 part of tetrabutyl titanate as a catalyst were charged. The temperature was gradually raised to 250 °C, and an esterification reaction was carried out over 4 hours. Then, the internal temperature was raised to 260 °C, 0.01 part of tetrabutyl titanate was charged as a catalyst, the pressure was reduced to 1.33 hPa, and a polymerization reaction was carried out over 3 hours to produce a polyester resin (i'-2). The bio-based plastic content of the obtained polyester resin (i'-2) was 56%, the ester group concentration was 7.7 mmol / g, the heat of crystal fusion was 0 J / g, the weight average molecular weight was 80,000, the glass transition temperature (Tg) was -49 °C, and the acid value was 0.4 mgKOH / g. The plant-derived raw material in Comparative Production Example 2 was sebacic acid, and the content relative to the polyester resin (i'-2) was 52%.

[0169] 〔Comparative Production Example 3: Production of polyester resin (i'-3)〕 Into a reaction vessel equipped with a thermometer, a stirrer, a rectification column, a nitrogen inlet tube, and a vacuum device, 17.8 parts (0.45 mol) of sebacic acid and 61.2 parts (0.55 mol) of hydrogenated distilled dimer acid (manufactured by Croda, "Pripol 1006") were charged as polycarboxylic acids (a), 20.6 parts (1.387 mol) of 1,3-propanediol and 0.3 parts (0.013 mol) of trimethylolpropane were charged as a polyol component (b), and 0.01 part of tetrabutyl titanate was charged as a catalyst. The temperature was gradually raised to 250 °C, and an esterification reaction was carried out over 4 hours. Thereafter, the internal temperature was raised to 260 °C, 0.01 part of tetrabutyl titanate was charged as a catalyst, the pressure was reduced to 1.33 hPa, and a polymerization reaction was carried out over 3 hours to produce a polyester resin (i'-3). The bioplastic degree of the obtained polyester resin (i'-3) was 100%, the ester group concentration was 4.49 mmol / g, the crystal melting heat was 0 J / g, the weight average molecular weight was 112,000, the glass transition temperature (Tg) was -56 °C, and the acid value was 0.5 mgKOH / g. The plant-derived raw materials in Comparative Production Example 3 were hydrogenated distilled dimer acid, sebacic acid, and 1,3-propanediol, and the contents of hydrogenated distilled dimer acid and sebacic acid with respect to the polyester resin (i'-3) were 83%.

[0170] [Comparative Production Example 4: Production of Polyester Resin (i'-4)] Into a reaction vessel equipped with a thermometer, a stirrer, a rectification column, a nitrogen inlet tube, and a vacuum device, 84.1 parts (1.00 mol) of hydrogenated distilled dimer acid (manufactured by Croda, "Pripol 1006") were charged as polycarboxylic acids (a), 15.6 parts (1.387 mol) of 1,3-propanediol and 0.3 parts (0.013 mol) of trimethylolpropane were charged as a polyol component (b), and 0.01 part of tetrabutyl titanate was charged as a catalyst. The temperature was gradually raised to 250 °C, and an esterification reaction was carried out over 4 hours. Thereafter, the internal temperature was raised to 260 °C, 0.01 part of tetrabutyl titanate was charged as a catalyst, the pressure was reduced to 1.33 hPa, and a polymerization reaction was carried out over 3 hours to produce a polyester resin (i'-4). The bioplastic content of the obtained polyester resin (i'-4) was 100%, the ester group concentration was 3.28 mmol / g, the heat of crystal fusion was 0 J / g, the weight average molecular weight was 157,000, the glass transition temperature (Tg) was -52 °C, and the acid value was 0.8 mgKOH / g. The plant-derived raw materials in Comparative Production Example 4 were hydrogenated distilled dimer acid and 1,3-propanediol, and the content of hydrogenated distilled dimer acid with respect to the polyester resin (i'-4) was 88%.

[0171] The compositions and physical properties of the polyester resins produced in the above production examples are shown in Tables 1 and 2 below.

[0172]

Table 1

[0173]

Table 2

[0174] Regarding the polyester resins produced in the above production examples, when the bioplastic content, ester group concentration, and heat of crystal fusion were confirmed, (i-1) to (i-6) all satisfied the ranges defined in the present invention and could be used as the polyester resin (i) or (ii) for the adhesive composition of the present invention.

[0175] On the other hand, the polyester resin (i'-2), which is a general polyester resin for adhesives, had a bioplastic content of about 56% and was insufficient for reducing the environmental load.

[0176] Next, prior to preparing the adhesive composition, each component was prepared as follows. 〔Hydrolysis inhibitor (iii)〕 · Carbodiimide-based compound (iii-1): "Carbodilite V-09GB" (manufactured by Nisshinbo Chemical Inc.) 〔Crosslinking agent (iv)〕 · Isocyanate crosslinking agent (iv-1): "Coronate HX" (manufactured by Tosoh Corporation) · Isocyanate crosslinking agent (iv-2): "Coronate L" (manufactured by Tosoh Corporation) 〔Urethanization catalyst (v)〕 · Zirconium-based compound (v-1): "Organix ZC-150" (manufactured by Matsumoto Fine Chemical Co., Ltd.) (diluted to a solid content concentration of 1% with acetylacetone) 〔Antioxidant (vi)〕 · Hindered phenol antioxidant (vi-1): "IRGANOX 1010" (manufactured by BASF) 〔Adhesion-imparting resin (vii)〕 · Aromatic hydrocarbon resin (vii-1): "FTR6100" (manufactured by Mitsui Chemicals, Inc.) (softening point: 95°C, acid value: less than 0.1 mgKOH / g) Bio-plasticity degree: 0% · Polymerized rosin ester (vii-2): "Haritac PCJ" (manufactured by Harima Chemicals, Inc.) (softening point: 118 - 128°C, acid value: 16 mgKOH / g or less) Bio-plasticity degree: 88% · Special rosin ester (vii-3): "Super Ester A-100" (manufactured by Arakawa Chemical Industries, Ltd.) (softening point: 100°C, acid value: 10 mgKOH / g or less) Bio-plasticity degree: 99% · Aromatic terpene (vii-4): "YS Resin TO115" (manufactured by Yasuhara Chemical Co., Ltd.) (softening point: 115°C, acid value: 0 mgKOH / g) Bio-plasticity degree: 70% or more · Terpene resin (vii-5): "YS Resin PX1000" (manufactured by Yasuhara Chemical Co., Ltd.) (softening point: 110°C, acid value: 0 mgKOH / g) Bio-plasticity degree: 90% or more

[0177] Next, using the polyester resins (i-1 to i-6 and i'-1 to i'-4) obtained above, an adhesive composition was prepared as in the following Examples and Comparative Examples, and an adhesive sheet was produced.

[0178] [Example 1] The polyester resin (i-1) obtained above was diluted with ethyl acetate to a solid content concentration of 50%. To 100 parts of the solid content, 1 part (solid content) of a carbodiimide compound (iii-1), 2 parts of an isocyanate-based crosslinking agent (iv-2), 0.02 part (solid content) of a zirconium compound (v-1), and 0.1 part of a hindered phenol-based antioxidant (vi-1) were added, and they were stirred and mixed to obtain an adhesive composition. The obtained adhesive composition was applied to a polyethylene terephthalate (PET) film (thickness 38 μm) so that the thickness after drying would be about 25 μm, and then dried at 100°C for 3 minutes to form an adhesive layer. Thereafter, a release-treated PET film (release film) was adhered to the adhesive layer to protect its surface, and it was cured for 10 days in an atmosphere at a temperature of 40°C to obtain an adhesive sheet.

[0179] [Examples 2 to 14, Comparative Examples 1 to 7] In Example 1, an adhesive composition was prepared and an adhesive sheet was obtained in the same manner except that the blending was carried out as shown in Table 3 below.

[0180]

Table 3

[0181] The obtained adhesive sheets of Examples 1 to 14 and Comparative Examples 1 to 7 were evaluated as follows. The evaluation results are shown in Table 4 below.

[0182] <Adhesive strength (peel strength) (against SUS-BA)> An SUS-BA plate was prepared as the adherend. The adhesive sheet obtained above was cut into 25 mm × 200 mm in an environment at 23°C and 50% RH, and then the release film was peeled off. The adhesive layer side was brought into contact with the SUS-BA plate, and a 2 kg roller was reciprocated to apply pressure and adhere it. After standing still for 30 minutes in the same atmosphere, using an autograph (manufactured by Shimadzu Corporation, Autograph AGS-H 500N), the 180-degree peel strength (N / 25 mm) was measured at a peel rate of 300 mm / min and evaluated according to the following criteria. (Evaluation criteria) ◎···5 N / 25 mm or more. ○ ··· 1 N / 25 mm or more and less than 5 N / 25 mm. × ··· less than 1 N / 25 mm.

[0183] <Adhesive strength after 24 hours (Peel strength after 24 hours)> A SUS-BA plate was prepared as the adherend. After cutting the adhesive sheet obtained above into 25 mm × 200 mm in an environment of 23°C and 50% RH, the release film was peeled off, the adhesive layer side was brought into contact with the SUS-BA plate, and a 2 kg roller was reciprocated for pressure bonding. Then, after standing still for 24 hours in the same atmosphere, using an autograph (manufactured by Shimadzu Corporation, Autograph AGS-H 500N), the 180-degree peel strength (N / 25 mm) was measured at a peel rate of 300 mm / min and evaluated according to the following criteria. (Evaluation criteria) ◎ ··· 20 N / 25 mm or more. ○ ··· 13 N / 25 mm or more and less than 20 N / 25 mm. × ··· less than 13 N / 25 mm.

[0184] <Adhesive strength (Peel strength) (against PP)> A polypropylene plate (PP) (manufactured by Nippon Test Panel Co., Ltd., PP 2.0 × 70 × 150 mm) was prepared as the adherend. After cutting the adhesive sheet obtained above into 25 mm × 200 mm in an environment of 23°C and 50% RH, the release film was peeled off, the adhesive layer side was brought into contact with the polypropylene plate (PP), and a 2 kg roller was reciprocated for pressure bonding. Then, after standing still for 30 minutes in the same atmosphere, using an autograph (manufactured by Shimadzu Corporation, Autograph AGS-H 500N), the 180-degree peel strength (N / 25 mm) was measured at a peel rate of 300 mm / min and evaluated according to the following criteria. (Evaluation criteria) ◎ ··· 10 N / 25 mm or more. ○ ··· 6 N / 25 mm or more and less than 10 N / 25 mm. × ··· less than 6 N / 25 mm.

[0185] <Retention force (Cohesion force)> The pressure-sensitive adhesive sheet obtained above was pasted onto SUS304 in accordance with JIS Z-0237 with a pasting area of 25 mm × 25 mm, and then allowed to stand at 80°C for 20 minutes. A load of 1 kg was applied to the sheet, and the time until it fell or, if it did not fall after standing for 24 hours, the deviation after 24 hours was measured and evaluated according to the following criteria. (Evaluation Criteria) ○ ··· It did not fall even after standing for 24 hours. × ··· It fell during the 24-hour standing period.

[0186] <Impact Resistance> The above pressure-sensitive adhesive composition was applied to a polyethylene terephthalate (PET) film (thickness: 38 μm) as a base material so that the dried thickness would be approximately 25 μm, and then dried at 100°C for 3 minutes to form a pressure-sensitive adhesive layer. Thereafter, a release-treated PET film (release film) was adhered to the pressure-sensitive adhesive layer, a 2-kg roller was placed on top of the release film, and after stopping for 10 seconds, the pressure-sensitive adhesive layer was visually observed and evaluated according to the following criteria. (Evaluation Criteria) ○ ··· No change. × ··· There are indentations remaining from where the roller was placed.

[0187] <Processability> When cutting the pressure-sensitive adhesive sheet obtained above into a width of 25 mm using a cutter knife, the adhesion of the paste to the blade of the cutter knife was visually observed and evaluated according to the following criteria. (Evaluation Criteria) ○ ··· No paste adhered to the blade. × ··· Paste adhered to the blade.

[0188] <Transparency> The release film was peeled off from the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet obtained above, and the exposed pressure-sensitive adhesive layer was bonded to a non-alkali glass plate (manufactured by Corning, Eagle XG). Thereafter, a test piece having a structure of PET film / pressure-sensitive adhesive layer / non-alkali glass plate was prepared. For this test piece, haze was measured using a HAZE MATER NDH2000 (manufactured by Nippon Denshoku Industries Co., Ltd.), and the haze value of the pressure-sensitive adhesive sheet was obtained by subtracting the haze value of the PET film, and evaluated according to the following criteria. The haze meter conforms to JIS K7361-1. ○···Haze is 3 or less. △···Haze exceeds 3 and is 10 or less. ×···Haze exceeds 10.

[0189]

Table 4

[0190] From the results in Table 4, the pressure-sensitive adhesive sheets of Examples 1 to 14 had desired adhesive physical properties not only for metal adherends but also for difficult-to-adhere adherends such as polyolefin resins, and were excellent in the balance between adhesive strength and holding power. Further, the pressure-sensitive adhesive sheets of Examples 1 to 14 were excellent in scratch resistance during the production of the pressure-sensitive adhesive sheet even when the width was narrowed, were excellent in processability as a pressure-sensitive adhesive sheet, and were also excellent in processability and transparency during bonding. Furthermore, it can be seen that by containing an adhesion-imparting resin, it has more excellent adhesive properties, and further adhesive properties over time. On the other hand, the adhesives of Comparative Examples 1 to 3 using conventional polyester resins with a high degree of biodegradability did not satisfy the adhesive physical properties, and the adhesive layer was too soft to cause scratches, and was inferior in processability and transparency. Further, in the adhesives of Comparative Examples 1 and 3 to 7 using polyester resins that do not use glycols having an even number of carbon atoms as the polyol component, the adhesive strength to polyolefin resins was insufficient, or the balance between adhesive strength and holding power was inferior.

[0191] In the above examples, specific forms of the present invention were shown, but the above examples are merely illustrative and are not to be construed in a limiting sense. Various modifications obvious to those skilled in the art are intended to be within the scope of the present invention.

Industrial Applicability

[0192] The adhesive of the present invention uses plant-derived raw materials that are friendly to the global environment, and even when using a polyester-based resin with a high degree of biodegradability, it has good adhesive properties to various adherends such as metals and plastics, and has excellent effects in processability, impact resistance, and transparency even during narrow-width processing. It is used for single-sided or double-sided adhesive sheets used for bonding optical members, single-sided or double-sided adhesive sheets for fixing members of portable electronic devices, and fixing electronic members, etc.

Claims

1. A pressure-sensitive adhesive obtained by crosslinking a pressure-sensitive adhesive composition containing a polyester resin (i) having a structural portion derived from a polyvalent carboxylic acid (a) and a structural portion derived from a polyol component (b), The polyester resin (i) contains 60% by weight or more of a structural portion derived from at least one selected from the group consisting of dimer acids, sebacic acids, and dimer diols, based on the weight of the polyester resin (i); As the polyol component (b), a glycol (b1) having an even number of carbon atoms (excluding dimer diol) ) The polyester resin (i) has an ester group concentration of 2 mmol / g or more; The adhesive strength (α) under the following conditions is 1N / 25mm or more A pressure-sensitive adhesive characterized by: Adhesive strength (α): When an adhesive sheet having an adhesive layer made of an adhesive formed on a substrate is formed, the sheet is attached to an adherend made of a SUS-BA plate and allowed to stand for 30 minutes in an environment of 23, 50% RH, after which the sheet exhibits a 180-degree peel strength (N / 25 mm) at a peel speed of 300 mm / min against the adherend.

2. The adhesive according to claim 1, characterized in that the glycol (b1) having an even number of carbon atoms is an aliphatic glycol having a straight chain structure.

3. 3. The pressure-sensitive adhesive according to claim 1, wherein the polyvalent carboxylic acids (a) contain 70 mol % or less of linear carboxylic acids (a1).

4. The pressure-sensitive adhesive according to any one of claims 1 to 3, characterized in that the polyol component (b) contains 10 to 100 mol % of a glycol (b1) having an even number of carbon atoms.

5. The pressure-sensitive adhesive according to any one of claims 1 to 4, characterized in that the glycol (b1) having an even number of carbon atoms is a polyol having 4 or less carbon atoms.

6. The pressure-sensitive adhesive according to any one of claims 1 to 5, characterized in that the acid value of the polyester resin (i) is 10 mgKOH / g or less.

7. The pressure-sensitive adhesive according to any one of claims 1 to 6, characterized in that the polyester resin (i) has a bioplasticity of 60% or more.

8. A pressure-sensitive adhesive composition containing a polyester resin (ii) having a bioplastic content of 60% or more is crosslinked, The polyester resin (ii) has a structural portion derived from a polyvalent carboxylic acid (a) and a structural portion derived from a polyol component (b), and the polyol component (b) is a glycol (b1) having an even number of carbon atoms (excluding dimer diol). ) The polyester resin (ii) has an ester group concentration of 2 mmol / g or more; The adhesive strength (α) under the following conditions is 1N / 25mm or more A pressure-sensitive adhesive characterized by: Adhesive strength (α): When an adhesive sheet having an adhesive layer made of an adhesive formed on a substrate is formed, the sheet is attached to an adherend made of a SUS-BA plate and allowed to stand for 30 minutes in an environment of 23, 50% RH, after which the sheet exhibits a 180-degree peel strength (N / 25 mm) at a peel speed of 300 mm / min against the adherend.

9. The pressure-sensitive adhesive according to any one of claims 1 to 8, characterized in that the pressure-sensitive adhesive composition further contains a hydrolysis inhibitor (iii).

10. The pressure-sensitive adhesive according to any one of claims 1 to 9, characterized in that the pressure-sensitive adhesive composition further contains a crosslinking agent (iv).

11. The pressure-sensitive adhesive according to any one of claims 1 to 10, characterized in that the pressure-sensitive adhesive composition further comprises a tackifier resin (vii).

12. The pressure-sensitive adhesive according to any one of claims 1 to 11, characterized in that the pressure-sensitive adhesive has a bioplasticity of 60% or more.

13. The pressure-sensitive adhesive according to any one of claims 1 to 12, which is used for bonding members.

14. A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive according to any one of claims 1 to 13.

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