Adhesives and adhesive sheets

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 pressure-sensitive adhesive and pressure-sensitive adhesive sheet, and more specifically to a pressure-sensitive adhesive and pressure-sensitive adhesive sheet that are made from environmentally friendly plant-derived raw materials, have good adhesive properties on various adherends such as metals and plastics, and are excellent in processability, dent resistance, and transparency. [Background technology]

[0002] In recent years, from the viewpoint of miniaturization and weight reduction of products, adhesives have come to be used for joining parts, etc., and adhesives using polyester-based resins and having excellent adhesive strength are also being considered as such adhesives.

[0003] Meanwhile, in recent years, as part of measures to combat the depletion of fossil fuel 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 that use plant-derived raw materials that are environmentally friendly.

[0004] As an example of such a polyester-based adhesive using plant-derived raw materials, Patent Document 1 describes a polyester-based adhesive containing, as a main component, a polyester-based polymer having alkyl groups in the molecular side chains, which is obtained by a condensation reaction between a plant-derived dicarboxylic acid and a plant-derived diol, and having a moisture permeability of 200 g / m 2 A low moisture-permeable pressure-sensitive adhesive sheet having the following pressure-sensitive adhesive layer has been proposed.

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

[0006] Although typical polyester resins are crystalline resins, how to break down the crystallinity is important when used in adhesives. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-308626 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-37463 Summary of the Invention [Problem to be solved by the invention]

[0008] However, the technology disclosed in Patent Document 1 uses long-chain alkyl raw materials, and the resulting polyester resin itself is very soft. Therefore, although the adhesive is highly bioplastic and environmentally friendly, the adhesive is soft and has very poor handleability when made into a narrow adhesive sheet. In addition, because the resin itself is too soft, it is difficult to neatly produce an adhesive sheet before crosslinking. Furthermore, the adhesive also has poor dent resistance. Further improvement is required in order to achieve both environmental friendliness and adhesive performance.

[0009] For example, in the case of adhesive sheets used to fix display protection members (such as cover glasses) of portable electronic devices, it is extremely important to narrow the width of the adhesive sheet from the viewpoints of increasing the screen size of the information display unit, improving design, and increasing design freedom.

[0010] When a pressure-sensitive adhesive sheet is made narrower, it becomes difficult to handle. That is, by narrowing the width, the surface area of ​​the pressure-sensitive adhesive sheet is reduced, but even with a separator film attached, the area of ​​the exposed adhesive on the side of the pressure-sensitive adhesive sheet remains the same, making it difficult to handle. Furthermore, when a pressure-sensitive adhesive sheet is made narrower, the pressure-sensitive adhesive sheet is slit, but because the slit width is narrower, problems such as the adhesive layer being pulled by the slitting blade are more likely to occur, which affects the performance of the pressure-sensitive adhesive sheet and causes problems. Furthermore, the adhesive adheres to the blade, which reduces processability and workability.

[0011] Furthermore, pressure-sensitive adhesive sheets that are compatible with the trend toward thinner display protection components for portable electronic devices, etc., are required to have non-sticky sides and, when slit, minimize deformation of the pressure-sensitive adhesive layer and adhesion of the pressure-sensitive adhesive to the blade. Furthermore, pressure-sensitive adhesives are required to have excellent dent resistance, which means that no dents are left when an external force is applied to the pressure-sensitive adhesive layer, and excellent transparency, which allows for the detection of abnormalities such as the inclusion of foreign matter.

[0012] Although the technology disclosed in Patent Document 2 above provides an adhesive that is highly bioplastic and environmentally friendly, the adhesive is still insufficient in terms of adhesive properties to adherends. In particular, the balance between holding power and adhesive power required for double-sided tapes and the like is not sufficient, and the adhesive properties to adherends that are difficult to adhere to, such as plastic substrates, particularly 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 is expected to be a plant-derived material, but it is prone to hydrolysis and requires high humidity and heat resistance, making it very difficult to use as an adhesive, and its use is discouraged.

[0014] Therefore, in this context, the present invention provides a pressure-sensitive adhesive and a pressure-sensitive adhesive sheet that have good adhesive properties for various adherends, excellent processability, dent resistance, and transparency, even though the pressure-sensitive adhesive uses plant-derived raw materials that are environmentally friendly. [Means for solving the problem]

[0015] However, the present inventors have discovered that in a pressure-sensitive adhesive obtained by crosslinking a pressure-sensitive adhesive composition containing a polyester resin, when a polyester resin with a high bioplasticity is used, which uses at least one plant-derived raw material such as dimer acids, sebacic acids, and dimer diol, and the polyol component that constitutes the polyester resin is made of a glycol component with an even number of carbon atoms, and by increasing the ester group concentration of the polyester resin and setting a high predetermined adhesive strength, it is possible to obtain a pressure-sensitive adhesive that is environmentally friendly, has good adhesive properties for various adherends, and is excellent in processability, dent resistance, and transparency even when made into a narrow width.

[0016] That is, the present invention provides a pressure-sensitive adhesive obtained by crosslinking a pressure-sensitive adhesive composition containing a polyester resin (i) having a structural moiety derived from a polycarboxylic acid (a) and a structural moiety derived from a polyol component (b), the polyester-based resin (i) contains 60% by weight or more of a structural moiety derived from at least one selected from the group consisting of dimer acids, sebacic acids, and dimer diols, based on the polyester-based resin (i); The polyol component (b) contains 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 first aspect 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 sheet is formed on a substrate with an adhesive layer made of an adhesive, it is attached to a SUS-BA plate substrate and left to stand for 30 minutes in an environment of 23°C and 50% RH, after which the 180-degree peel strength (N / 25 mm) is measured at a peel speed of 300 mm / min against the substrate.

[0017] The present invention also provides a pressure-sensitive adhesive obtained by crosslinking a pressure-sensitive adhesive composition containing a polyester-based resin (ii) having a bioplasticity of 60% or more, the polyester resin (ii) has a structural moiety derived from a polycarboxylic acid (a) and a structural moiety derived from a polyol component (b), and the polyol component (b) contains 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 second aspect 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 sheet is formed on a substrate with an adhesive layer made of an adhesive, it is attached to a SUS-BA plate substrate and left to stand for 30 minutes in an environment of 23°C and 50% RH, after which the 180-degree peel strength (N / 25 mm) is measured at a peel speed of 300 mm / min against the substrate.

[0018] Furthermore, a third aspect of the present invention is a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive according to the first or second aspect.

[0019] Typically, raw materials with a high bioplastic content are mostly long-chain alkyl-based materials, such as sebacic acid derived from castor oil, dimer acid derived from oleic acid, and dimer diols made from these dimer acids. For example, sebacic acid is a monomer that is highly crystalline when made into polyester resins, and polyester resins derived from sebacic acid are used as crystalline polyester resins. On the other hand, dimer acid and dimer diol are monomers used to soften and water-resistant resins, and in order to improve their physical properties, it is advantageous to have as low an ester group concentration as possible, so it is preferable to reduce the ester group concentration as much as possible.

[0020] Furthermore, when attempting to produce a pressure-sensitive adhesive using a polyester resin, it is generally necessary to lower the glass transition temperature. Therefore, a glycol material containing an alkyl dicarboxylic acid and an alkyl group with 5 or more carbon atoms, such as a branched glycol such as neopentyl glycol (5 carbon atoms), is used to break down the crystallinity, and a relatively long-chain glycol such as 1,6-hexanediol (6 carbon atoms) is used to soften the adhesive. These glycol materials can break down the crystallinity of the polyester resin, lower the glass transition temperature, and improve adhesive strength. When using glycols with a low carbon number, i.e., glycols with 4 or fewer carbon atoms, the softness is likely to be insufficient, resulting in insufficient adhesive properties. Therefore, it is generally not considered appropriate to use glycols with 4 or fewer carbon atoms as the main component.

[0021] However, in the present invention, the polyester resin surprisingly has a high bioplasticity, but by using a glycol with an even number of carbon atoms as the polyol component, increasing the molecular alignment and designing it so that crystallization does not actually occur, and by using a plant-derived long-chain monomer while increasing the ester group concentration, the object of the present invention has been achieved.

[0022] For example, when a pressure-sensitive adhesive is made using a polyester resin using dimer acid and dimer diol as the main components, the long main chain and side chain alkyl chains result in a very soft resin, which significantly deteriorates "dent resistance during molding of the pressure-sensitive adhesive sheet" and "processability when cutting the finished pressure-sensitive adhesive sheet to the required size." In the present invention, for example, by using dimer acid and appropriate sebacic acid to soften the resin, while using a small glycol such as ethylene glycol or 1,4-butanediol as the glycol, the concentration of ester bonds, which are hard components, is maximized, thereby improving the dent resistance and processability of the pressure-sensitive adhesive made using a polyester resin.

[0023] Furthermore, for example, when a glycol component with an even number of carbon atoms, such as ethylene glycol or 1,4-butanediol, is used, compared to when a glycol component with an odd number of carbon atoms, such as 1,3-propanediol, is used, it is more likely that a structure will be formed in which some of the polymer chains are aligned, which is thought to increase the cohesive force within the resin, and as a result, it is presumed that the adhesive strength required for the double-sided tape will be higher. [Effects of the Invention]

[0024] The pressure-sensitive adhesive of the present invention is a pressure-sensitive adhesive obtained by crosslinking a pressure-sensitive adhesive composition containing a polyester-based resin (i) having structural moieties derived from a polycarboxylic acid (a) and structural moieties derived from a polyol component (b), wherein the polyester-based resin (i) contains at least 60 wt% of structural moieties derived from at least one selected from the group consisting of dimer acids, sebacic acids, and dimer diols, relative to the polyester-based resin (i), and the polyol component (b) is a polyester-based resin containing a glycol (b1) having an even number of carbon atoms (excluding dimer diols), and the polyester-based resin (i) has an ester group concentration of 2 mmol / g or more and an adhesive strength (α) under the above conditions of 1 N / 25 mm or more. Therefore, while the pressure-sensitive adhesive has a high bioplasticity and is environmentally friendly, it contains a polyester-based resin with a high ester group concentration, has good adhesive properties on various adherends, and exhibits excellent processability, dent resistance, and transparency even when narrowed. Therefore, it can be effectively used as a single-sided or double-sided pressure-sensitive adhesive sheet for laminating optical members, or as a single-sided or double-sided pressure-sensitive adhesive sheet for fixing members of portable electronic devices or electronic members.

[0025] When the glycol (b1) having an even number of carbon atoms is an aliphatic glycol having a straight chain structure, a pressure-sensitive adhesive having an excellent balance between crystallinity and cohesive strength can be obtained.

[0026] When the polyvalent carboxylic acid (a) contains 70 mol % or less of the straight-chain carboxylic acid (a1), a pressure-sensitive adhesive having a better balance between crystallinity and cohesive strength can be obtained.

[0027] When the polyol component (b) contains 10 to 100 mol % of glycols (b1) having an even number of carbon atoms, a pressure-sensitive adhesive having superior adhesive strength can be obtained.

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

[0029] When the acid value of the polyester resin (i) is 10 mgKOH / g or less, a pressure-sensitive adhesive having excellent durability can be obtained.

[0030] When the polyester resin (i) has a bioplastic content of 60% or more, the pressure-sensitive adhesive can be made more environmentally friendly.

[0031] The pressure-sensitive adhesive of the present invention is a pressure-sensitive adhesive obtained by crosslinking a pressure-sensitive adhesive composition containing a polyester-based resin (ii) having a bioplasticity of 60% or more, the polyester-based resin (ii) having a structural moiety derived from a polycarboxylic acid (a) and a structural moiety derived from a polyol component (b), the polyol component (b) containing a glycol (b1) having an even number of carbon atoms (excluding dimer diol), the ester group concentration of the polyester-based resin (ii) being 2 mmol / g or more, and the adhesive strength (α) under the above conditions being 1 N / 25 mm or more. Therefore, while the pressure-sensitive adhesive has a high bioplasticity and is environmentally friendly, it contains a polyester-based resin with a high ester group concentration, has good adhesive properties on various adherends, and exhibits excellent processability, dent resistance, and transparency even when made into a narrow width. Therefore, it can be effectively used as a single-sided or double-sided pressure-sensitive adhesive sheet for laminating optical members, or as a single-sided or double-sided pressure-sensitive adhesive sheet for fixing members of portable electronic devices or electronic members.

[0032] When the pressure-sensitive adhesive composition further contains a hydrolysis inhibitor (iii), the pressure-sensitive adhesive composition can have excellent long-term durability.

[0033] When the pressure-sensitive adhesive composition further contains a crosslinking agent (iv), the pressure-sensitive adhesive composition can have even better adhesive strength.

[0034] If the pressure-sensitive adhesive composition further contains a tackifying resin (vii), the pressure-sensitive adhesive can have even more excellent adhesive properties.

[0035] Furthermore, if the adhesive has a bioplastic content of 60% or more, the adhesive can be made more environmentally friendly. DETAILED DESCRIPTION OF THE INVENTION

[0036] The configuration of the present invention will be described in detail below, but these are merely examples of preferred embodiments. In the present invention, the term "carboxylic acids" includes not only carboxylic acids but also carboxylic acid derivatives such as hydrogenated carboxylic acids, carboxylic acid salts, carboxylic acid anhydrides, carboxylic acid halides, and carboxylic acid esters.

[0037] The adhesive composition forming the adhesive of the present invention is an adhesive composition containing a polyester-based resin (i) having structural moieties derived from polycarboxylic acids (a) and structural moieties derived from a polyol component (b), wherein the polyester-based resin (i) contains structural moieties 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 relative to the polyester-based resin (i), the polyol component (b) contains a glycol (b1) having an even number of carbon atoms (excluding dimer diols), and the polyester-based resin (i) has an ester group concentration of 2 mmol / g or more.

[0038] The pressure-sensitive adhesive composition forming the pressure-sensitive adhesive of the present invention is a pressure-sensitive adhesive composition containing a polyester-based resin (ii) having a bioplasticity of 60% or more, wherein the polyester-based resin (ii) has a structural moiety derived from a polycarboxylic acid (a) and a structural moiety derived from a polyol component (b), and the polyol component (b) contains a glycol (b1) having an even number of carbon atoms (excluding dimer diol), and the polyester-based resin (ii) has an ester group concentration of 2 mmol / g or more.

[0039] Each component constituting the pressure-sensitive adhesive composition of the present invention will be described below in order.

[0040] <Polyester-based resins (i) and (ii)> The polyester resins (i) and (ii) used in the present invention have a structural portion derived from a polycarboxylic acid (a) and a structural portion derived from a polyol component (b), and are obtained, for example, by copolymerizing a copolymerization component containing a polycarboxylic acid (a) and a polyol component (b).

[0041] [Polycarboxylic acids (a)] In the present invention, it is preferable to use plant-derived polycarboxylic acids in order to increase the degree of bioplasticity. 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. Note that, 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 raw material availability and ease of production, more preferably linear carboxylic acids having 4 to 12 carbon atoms, and even more preferably linear carboxylic acids having 6 to 10 carbon atoms, and sebacic acids are particularly preferable in terms of lowering the glass transition temperature and facilitating adjustment of adhesive properties.

[0043] The polyester resins (i) and (ii) used in the present invention contain a structural moiety derived from a polycarboxylic acid (a), and preferably contain 70 mol% or less of a linear carboxylic acid (a1) as the polycarboxylic acid (a), particularly preferably 5 to 70 mol%, and further preferably 10 to 60 mol%. If the content is too high, crystallinity tends to increase. On the other hand, if the content is too low, production stability tends to decrease.

[0044] As the polycarboxylic acid (a), it is preferable to use a dimer acid (a2) since crystallization is easily prevented, and more preferably a hydrogenated product of a dimer acid.

[0045] The dimer acid (a2) is 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 acid (a). The upper limit is usually 100 mol%. If the content is too low, crystallinity tends to increase.

[0046] As the 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] Polycarboxylic acids other than those mentioned above may also be used within the scope of the present invention. Examples of such polycarboxylic acids other than those mentioned 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, and 1,9-nonanedicarboxylic acids; phthalic acids, terephthalic acids, isophthalic acids, benzylmalonic acids, diphenic acids, 4,4'-oxydibenzoic acids, and further 1,8-naphthalenedicarboxylic acids, 2, Examples of the dicarboxylic acid include aromatic dicarboxylic acids such as naphthalenedicarboxylic acids, such as 3-naphthalenedicarboxylic acids and 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 and adamantanedicarboxylic acids; and trivalent or higher carboxylic acids such as trimellitic acids, pyromellitic acids, adamantanetricarboxylic acids and trimesic acids.

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

[0049] [Polyol component (b)] In the present invention, it is preferable to use a plant-derived polyol component in order to increase the degree of bioplasticity. Examples of the plant-derived polyol component include fatty acid ester 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., dimer diols obtained by converting their hydrogenated products into diols, bioethylene glycol, biopropylene glycol, biobutylene glycol, etc. Among these, bioethylene glycol and biopropane glycol (1,3-propanediol) are preferred because they allow for an easy increase in the ester group concentration, and bioethylene glycol is particularly preferred.

[0050] In the present invention, it is necessary to use, as the polyol component (b), a glycol (b1) having an even number of carbon atoms (excluding dimer diol) in order to break down crystallinity while increasing molecular alignment and imparting cohesive strength.

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

[0052] Among the glycols (b1) having an even number of carbon atoms, aliphatic glycols are preferred, and aliphatic glycols having a straight chain structure are particularly preferred from the viewpoint of the balance between crystallinity and cohesive strength.

[0053] In order to increase the ester bond concentration and in terms of production stability, it is preferable to use a glycol having 4 or less carbon atoms as the glycol (b1) having an even number of carbon atoms, and it is particularly preferable to use a glycol having 2 carbon atoms.

[0054] Preferred specific examples of the glycol (b1) having an even number of carbon atoms used in the present invention include aliphatic glycols having a straight chain structure and 4 or less carbon atoms, such as ethylene glycol, diethylene glycol, and 1,4-butanediol, of which ethylene glycol and 1,4-butanediol are preferred, with ethylene glycol being particularly preferred.

[0055] In the present invention, the content of the glycol (b1) having an even number of carbon atoms is preferably 10 to 100 mol %, particularly preferably 30 to 99.9 mol %, further preferably 50 to 99.7 mol %, and particularly preferably 70 to 99.6 mol %, based on the total polyol component (b). If the content is too low, the adhesive 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 and trihydric or higher polyhydric alcohols.

[0057] Examples of glycols having an odd number of carbon atoms include aliphatic glycols such as aliphatic glycols having a linear structure, such as 1,3-propanediol, 1,5-pentanediol, and 1,9-nonanediol, and 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, etc., and their ethylene oxide and propylene oxide adducts; etc.

[0058] Examples of the trihydric or higher polyhydric alcohol include pentaerythritol, dipentaerythritol, tripentaerythritol, glycerin, trimethylolpropane, trimethylolethane, 1,3,6-hexanetriol, and adamantanetriol.

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

[0060] Furthermore, when the polycarboxylic acid (a) has a high bioplasticity, a non-plant-derived polyol component may be used as the polyol component (b) in terms of ease of polycondensation. However, even in this case, it is preferable to use a polyol having 4 or fewer carbon atoms, and it is particularly preferable to use a polyol having 2 carbon atoms, in order to increase the bioplasticity. That is, when a polyol component (b) having a carbon number of 4 or fewer is used, the weight ratio of the carboxylic acid (a) having a high bioplasticity in the polyester resins (i) and (ii) increases, thereby increasing the bioplasticity. Specific examples of polyols having 4 or fewer carbon atoms include ethylene glycol and 1,4-butanediol.

[0061] The polyol component (b) may be used alone or in combination of two or more.

[0062] In addition to the polyol component (b) and the polyvalent carboxylic acids (a), compounds having both a carboxylic acid and a hydroxyl group in the molecule (e.g., lactic acid) can also be used within the scope that does not impair the effects of the present invention. However, since lactic acid is prone to hydrolysis, it is more preferable not to use it.

[0063] To achieve a high bioplasticity, the polyester resins (i) and (ii) used in the present invention preferably 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, even more preferably 70% by weight or more, and particularly preferably 80% by weight or more, based on the copolymerization components of the polyester resin (i). The upper limit is 100% by weight. If the content is too low, the resulting polyester resins (i) and (ii) will have a low bioplasticity, and the reduction in environmental impact will tend 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 polycondensation of a polycarboxylic acid (a) and a polyol component (b) in the presence of a catalyst by a known method, and in the polycondensation reaction, an esterification reaction or an ester exchange reaction is carried out first, followed by the polycondensation reaction. When a high molecular weight is not required, the polyester resins may be produced by only an esterification reaction or an ester exchange reaction.

[0065] In such an esterification reaction or transesterification reaction, a catalyst is usually used, and specific examples include 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, and one or more of these are used. Among these, antimony trioxide, tetrabutyl titanate, germanium dioxide, and zinc acetate are preferred from the standpoint of the balance between high catalytic activity and the hue of the resulting reaction product.

[0066] The amount of the catalyst to be added is preferably 1 to 10,000 ppm, particularly preferably 10 to 5,000 ppm, and further preferably 20 to 3,000 ppm, based on the total weight of the copolymerization components. If the amount is too small, the polymerization reaction tends to proceed insufficiently, whereas if the amount is too large, there is no advantage such as shortening the reaction time, and side reactions tend to occur easily.

[0067] The reaction temperature during the esterification reaction is preferably 200 to 300°C, particularly preferably 210 to 280°C, and even more preferably 220 to 260°C. If the reaction temperature is too low, the reaction tends to proceed insufficiently, while if it is too high, side reactions such as decomposition tend to occur. The pressure during the reaction is usually normal pressure.

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

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

[0070] In order to achieve a high bioplasticity, the polyester resin (i) used in the present invention must contain at least 60% by weight of structural moieties derived from at least one selected from the group consisting of dimer acids, sebacic acids, and dimer diols, based on the polyester resin (i). This is 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 structural moieties is low, the bioplasticity of the polyester resin (i) will be low, and the reduction of environmental impact will be insufficient.

[0071] The ester group concentration of the 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 the ester group concentration is too low, the polyester resin becomes soft, resulting in poor dent resistance and processability. Examples of methods for adjusting the ester group concentration within a predetermined range include selecting a polyol having 4 or less carbon atoms as the polyol component (b), increasing the content of linear carboxylic acids (a1) as the polyvalent carboxylic acids (a), and combining both of these methods.

[0072] The ester group concentration (mmol / g) refers to the number of moles of ester bonds in 1 g of polyester resin, and can be calculated, for example, from the amounts charged. The calculation is calculated by dividing the number of moles of the polycarboxylic acid (a) or the polyol component (b), whichever is charged less frequently, by the total weight of the finished product, and an example of the calculation formula is shown below. Note that the calculation method will need to be changed appropriately when using a monomer having both a carboxylic acid and a hydroxyl group, or when preparing polyester from caprolactone, etc.

[0073] <When the amount of polycarboxylic acids (a) is small> Ester group concentration (mmol / g) = [(A1 / a1 × m1 + A2 / a2 × m2 + A3 / a3 × m3 ) / Z] × 1000 A: Amount of polycarboxylic acid (a) (g) a: Molecular weight of polycarboxylic acid (a) m: number of carboxyl groups per molecule of polycarboxylic acid (a) Z: Finished weight (g)

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

[0075] The ester group concentration can also be measured by a known method such as NMR.

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

[0077] The bioplasticity 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 the bioplasticity is low, the reduction of the environmental load will be insufficient.

[0078] The upper limit of the bioplastic degree is 100%. Methods for adjusting the bioplastic degree within a predetermined range include using mainly plant-derived polycarboxylic acids or plant-derived polyol components, but it is particularly preferable to use plant-derived polycarboxylic acids (a) in order to efficiently increase the bioplastic degree.

[0079] Here, the bioplastic degree of the polyester resins (i) and (ii) refers to the proportion of carbon from plant-derived raw materials used in producing the polyester resins (i) and (ii) incorporated into the resin relative to the total carbon in the polyester resins (i) and (ii), and is calculated as follows:

[0080] The bioplasticity of the polycarboxylic acids (a), polyol component (b) and other components (e.g., compounds having a carboxyl group and a hydroxyl group in the molecule) is calculated from the weighted average of the respective bioplasticities.

[0081] (Calculation method) <When polycondensation reaction occurs> Bioplastic content (%) = [(number of moles of carbon in plant-derived monomers when the molar ratio of each component is calculated from the molar ratio of the charged amounts of polycarboxylic acids (a) and polyol component (b) assuming a molar ratio of carboxyl groups to hydroxyl groups of 1:1)) / (number of moles of carbon in all constituent monomers)] × 100 <When no polycondensation reaction is involved> Bioplastic content (%) = [(number of moles of carbon in plant-derived monomers) / (number of moles of carbon in all constituent monomers)] x 100

[0082] The bioplastic degree can also be determined by analyzing the composition ratio of the resin by NMR and calculating the carbon number of the plant-derived monomer / total carbon number.

[0083] Furthermore, the bioplastic content can also be measured by a method in accordance with "ASTM D-6866" (measurement of natural radioactive carbon (C-14) concentration).

[0084] The crystalline heat of fusion of the polyester resins (i) and (ii) measured by a differential scanning calorimeter (DSC) is preferably 10 J / g or less, more preferably 5 J / g or less, even more preferably 2 J / g or less, and particularly preferably no crystalline heat of fusion is exhibited. If the crystalline heat of fusion is too large, crystallinity will be exhibited, which tends to result in poor storage stability of the resin solution and poor stability and adhesive properties at low temperatures when made into a pressure-sensitive adhesive sheet.

[0085] Examples of methods for adjusting the heat of crystalline fusion within a predetermined range include a method of appropriately using polycarboxylic acids having an alkyl group on the side chain or a polyol component having an alkyl group on the side chain, and a method of using three or more, preferably four or more, copolymerizable monomer components.

[0086] The heat of crystalline 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 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, handling properties will be reduced, requiring a large amount of solvent and the environmental load will tend to increase, whereas if the weight-average molecular weight is too small, adhesive properties will tend to decrease.

[0088] The weight-average molecular weights mentioned above are those calculated in terms of standard polystyrene molecular weights. The high-performance liquid chromatograph (Tosoh Corporation, "HLC-8320GPC") was used with a column: TSKgel SuperMultipore HZ-M (exclusion limit molecular weight: 2 × 10 6 The measurement is performed using two columns in series (theoretical plate number: 16,000 / column, filler material: styrene-divinylbenzene copolymer, filler particle size: 4 μm).

[0089] The acid value of the polyester resins (i) and (ii) is preferably 10 mgKOH / g or less in order to prevent hydrolysis and improve durability, more preferably 5 mgKOH / g or less, particularly preferably 2 mgKOH / g or less, and especially preferably 1 mgKOH / g or less. If the acid value is too high, durability tends to decrease. The acid value can be adjusted, for example, by increasing the proportion of the polyol component (b) during the esterification reaction or transesterification reaction, or by adjusting the reaction conditions. The lower limit of the acid value is usually 0 mgKOH / g.

[0090] The acid values ​​of the polyester resins (i) and (ii) are determined by neutralization titration in accordance with JIS K0070. The acid value in the present invention refers to the content of carboxy groups in the polyester resins (i) and (ii). The carboxy groups include those in a carboxylate ion state in which the carboxy groups are neutralized with a basic compound.

[0091] The glass transition temperature (Tg) of the polyester resins (i) and (ii) is preferably −90 to 20° C., particularly preferably −80 to 0° C., further preferably −60 to −20° C., and particularly preferably −50 to −30° C. If the glass transition temperature (Tg) is too high, the adhesiveness of the resulting pressure-sensitive adhesive composition tends to decrease, whereas if it is too low, the heat resistance and cohesive strength tend to decrease. The glass transition temperature can be adjusted by, for example, introducing an aromatic skeleton or changing the alkyl chain length of the polycarboxylic acid component or glycol component.

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

[0093] The pressure-sensitive adhesive composition of the present invention preferably contains, in addition to the 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), and the like.

[0094] <Hydrolysis inhibitor (iii)> The hydrolysis inhibitor (iii) is contained to ensure long-term durability. As the hydrolysis inhibitor (iii), a conventionally known compound can be used, for example, a compound that reacts with and bonds to the carboxyl terminal of the polyester resins (i) and (ii), specifically, for example, a compound containing a functional group such as a carbodiimide group, an epoxy group, an oxazoline group, etc. Among these, a carbodiimide group-containing compound is preferred because it is highly effective in eliminating the catalytic activity of protons derived from the carboxyl terminal.

[0095] As the carbodiimide group-containing compound, a known carbodiimide having one or more carbodiimide groups (-N=C=N-) in the molecule can usually be used. However, in order to improve durability under high temperature and high humidity, a compound having two or more carbodiimide groups in the molecule, i.e., a polyvalent carbodiimide compound, is preferred. In particular, a compound having three or more, even five or more, and especially seven or more carbodiimide groups in the molecule is preferred. 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, which tends to reduce compatibility. It is also preferred to use a high-molecular-weight polycarbodiimide produced by decarboxylation condensation reaction of diisocyanate in the presence of a carbodiimidization catalyst.

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

[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'-diphenylether diisocyanate, 3,3'-dimethyl-4,4'-diphenylether diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1-methoxyphenyl-2,4-diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and tetramethylxylylene diisocyanate. These can be used alone or in combination of two or more. Such high molecular weight polycarbodiimides can be synthesized or commercially available products can be used.

[0099] Commercially available examples of the carbodiimide group-containing compound include the Carbodilite (registered trademark) series manufactured by Nisshinbo Chemical Inc. Among these, Carbodilite (registered trademark) "V-01," "V-02B," "V-03," "V-04K," "V-04PF," "V-05," "V-07," "V-09," and "V-09GB" are preferred because of their excellent compatibility with organic solvents.

[0100] The epoxy group-containing compound is preferably, for example, a glycidyl ester compound or a glycidyl ether compound.

[0101] Specific examples of the glycidyl ester compound include benzoic acid glycidyl ester, t-Bu-benzoic acid glycidyl ester, p-toluic acid glycidyl ester, cyclohexanecarboxylic acid glycidyl ester, pelargonic acid glycidyl ester, stearic acid glycidyl ester, lauric acid glycidyl ester, palmitic acid glycidyl ester, behenic acid glycidyl ester, versatic acid glycidyl ester, oleic acid glycidyl ester, linoleic acid glycidyl ester, linolenic acid glycidyl ester, behenolic acid glycidyl ester, stearolic acid glycidyl ester, terephthalic acid diglycidyl ester, and isophthalic acid. Examples of the diglycidyl ester include diglycidyl ester, diglycidyl phthalate, diglycidyl naphthalenedicarboxylic acid, diglycidyl ester of methyl terephthalate, diglycidyl hexahydrophthalate, diglycidyl tetrahydrophthalate, diglycidyl ester of cyclohexanedicarboxylic acid, diglycidyl ester of adipic acid, diglycidyl ester of succinic acid, diglycidyl ester of sebacic acid, diglycidyl ester of dodecanedioic acid, diglycidyl ester of octadecanedicarboxylic acid, triglycidyl trimellitate, and tetraglycidyl ester of pyromellitic acid. These may be used alone or in combination of two or more.

[0102] Specific examples of the glycidyl ether compound include 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 bisglycidyl polyethers obtained by reacting bisphenols such as 2,2-bis-(4-hydroxyphenyl)propane and 2,2-bis-(4-hydroxyphenyl)methane with epichlorohydrin, and these can be used alone or in combination of two or more.

[0103] The oxazoline group-containing compound is preferably a bisoxazoline compound, etc. Specific examples include 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-methyl ... ,2'-bis(4-phenyl-2-oxazoline), 2,2'-bis(4-cyclohexyl-2-oxazoline), 2,2'-bis(4-benzyl-2-oxazoline), 2,2'-p-phenylenebis(2-oxazoline), 2,2'-m-phenylenebis(2-oxazoline), 2,2'-o-phenylenebis(2-oxazoline), 2,2'-p-phenylenebis(4-methyl-2-oxazoline), 2,2'-p-phenylenebis(4,4-dimethyl- 2-oxazoline), 2,2'-m-phenylenebis(4-methyl-2-oxazoline), 2,2'-m-phenylenebis(4,4-dimethyl-2-oxazoline), 2,2'-ethylenebis(2-oxazoline), 2,2'-tetramethylenebis(2-oxazoline), 2,2'-hexamethylenebis(2-oxazoline), 2,2'-octamethylenebis(2-oxazoline), 2,2'-decamethylenebis(2-oxazoline), 2,2'-ethylenebis Examples of suitable bis(4-methyl-2-oxazoline), 2,2'-tetramethylenebis(4,4-dimethyl-2-oxazoline), 2,2'-9,9'-diphenoxyethanebis(2-oxazoline), 2,2'-cyclohexylenebis(2-oxazoline), 2,2'-diphenylenebis(2-oxazoline), etc., are listed below. Among these, 2,2'-bis(2-oxazoline) is most preferred from the viewpoint of reactivity with the polyester resins (i) and (ii). These bis(2-oxazoline) can be used alone or in combination of two or more.

[0104] The hydrolysis inhibitor (iii) preferably has low volatility, and therefore it is preferable to use one with a high number average molecular weight, which is usually 300 to 10,000, preferably 1,000 to 5,000.

[0105] Furthermore, from the viewpoint of hydrolysis resistance, it is preferable to use a hydrolysis inhibitor (iii) having a high weight-average molecular weight. The weight-average molecular weight of the hydrolysis inhibitor (iii) is preferably 500 or more, more preferably 2000 or more, and even more preferably 3000 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, whereas if the molecular weight is too large, the compatibility with the polyester resins (i) and (ii) tends to decrease.

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

[0108] The content of the 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, relative to 100 parts by weight of the polyester resin (i) or (ii). If the content is too high, turbidity tends to occur due to poor compatibility with the polyester resin (i) or (ii), while if the content is too low, sufficient durability tends to be difficult to obtain.

[0109] The content of the hydrolysis inhibitor (iii) is preferably optimized depending on the acid value of the polyester resin (i) or (ii), and the molar ratio [(y) / (x)] of the total number of moles (y) of functional groups of the hydrolysis inhibitor (iii) in the PSA composition to the total number of moles (x) of acidic functional groups of the polyester resin (i) or (ii) in the PSA composition is preferably 0.5≦(y) / (x), particularly preferably 1≦(y) / (x)≦1000, and even more preferably 1.5≦(y) / (x)≦100. If the molar ratio of (y) to (x) is too low, the moisture and heat resistance tends to decrease, whereas if 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 strength, and durability tend to decrease.

[0110] <Crosslinking agent (iv)> The pressure-sensitive adhesive composition of the present invention preferably further contains a crosslinking agent (iv). By containing the crosslinking agent (iv), the polyester resin (i) or (ii) is crosslinked by the crosslinking agent (iv), resulting in an adhesive having excellent cohesive strength and improving performance as a pressure-sensitive adhesive.

[0111] Examples of such crosslinking agents (iv) include compounds having functional groups that react with at least one of the hydroxyl and carboxyl groups contained in the polyester resins (i) and (ii), such as polyisocyanate compounds and polyepoxy compounds. Furthermore, polyfunctional acrylic monomers and urethane acrylate oligomers that increase cohesive strength without reacting with the polyester resins (i) and (ii) can also be used. Among these, polyisocyanate compounds are particularly preferred because they can achieve a good balance between initial adhesion, 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, and triphenylmethane triisocyanate. Other examples include adducts of the above polyisocyanates with polyol compounds such as trimethylolpropane, and biuret and isocyanurate forms of these polyisocyanate compounds. The above polyisocyanate compounds may also be used in which the isocyanate moiety is blocked with phenol, lactam, or the like. These crosslinking agents (iv) may be used alone or in combination.

[0113] The content of the crosslinking agent (iv) can be appropriately selected depending on the molecular weight of the polyester resins (i) and (ii) and the intended use, but it is usually preferable to contain the crosslinking agent (iv) in a proportion such that the reactive group contained in the crosslinking agent (iv) is 0.2 to 10 equivalents per equivalent of at least one of the hydroxyl group and the carboxyl group contained in the polyester resin (i) or (ii), particularly preferably 0.5 to 5 equivalents, and even more preferably 0.5 to 3 equivalents. If the equivalent number of the reactive group contained in the crosslinking agent (iv) is too small, the cohesive strength tends to decrease, and if it is too large, the flexibility tends to decrease.

[0114] The content of the 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, per 100 parts by weight of the polyester resin (i) or (ii). If the amount of such crosslinking agent is too small, the cohesive strength tends to decrease, whereas if the amount is too large, the flexibility tends to decrease and the required adhesive strength tends to become difficult to obtain.

[0115] In the reaction between the polyester resins (i) and (ii) and the crosslinking agent (iv), organic solvents that do not have functional groups that react with the components (i), (ii), and (iv) can be used, such as esters such as ethyl acetate and butyl acetate, ketones such as methyl ethyl ketone and methyl isobutyl ketone, and aromatics such as toluene and xylene. These can be used alone or in combination of two or more.

[0116] <Urethanization catalyst (v)> In view of the reaction rate, the pressure-sensitive adhesive composition of the present invention preferably contains a urethanization catalyst (v).

[0117] Examples of the urethanization catalyst (v) include organometallic compounds, tertiary amine compounds, etc. These can be used alone or in combination of two or more kinds.

[0118] Examples of the organometallic compounds include zirconium compounds, iron compounds, tin compounds, titanium compounds, lead compounds, cobalt compounds, and zinc compounds. 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, and dibutyltin dilaurate.

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

[0120] Among these urethanization catalysts (v), organometallic compounds are preferred, and zirconium compounds are particularly preferred, in terms of reaction rate and pot life of the adhesive layer. Furthermore, the urethanization catalyst (v) is preferably used in combination with acetylacetone as a catalytic inhibitor. The inclusion of acetylacetone is preferred in that it inhibits catalytic activity at low temperatures and extends pot life.

[0121] The content of the urethanization catalyst (v) is preferably 0.0001 to 1 part by weight, particularly 0.001 to 0.1 part by weight, and even more preferably 0.01 to 0.05 part by weight, per 100 parts by weight of the polyester resin (i) or (ii). If the content is too low, the aging time until the crosslinking reaction is completed tends to be long, while if the content is too high, the adhesive properties tend to be reduced.

[0122] <Antioxidants (vi)> The pressure-sensitive adhesive composition of the present invention preferably contains an antioxidant (vi) in order to increase 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, etc. Among these, at least one selected from the group consisting of hindered phenol-based antioxidants, amine-based antioxidants, and phosphoric acid-based antioxidants is preferred, and antioxidants consisting of hindered phenol-based compounds are particularly preferred. Examples of hindered phenol-based antioxidants include antioxidants having a hindered phenol structure in which a group with large steric hindrance, such as a tertiary butyl group, is bonded to at least one of the carbon atoms adjacent to the carbon atom on the aromatic ring to which the phenolic hydroxyl group 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 even more preferably 0.05 to 5 parts by weight, relative to 100 parts by weight of the polyester resin (i) or (ii). If the content is too low, adhesive residue on the adherend tends to occur, whereas if the content is too high, adhesive properties tend to decrease.

[0125] <Tackifying resin (vii)> In the present invention, it is preferable to contain a tackifying resin (vii) in order to improve adhesive properties.

[0126] The tackifier resin (vii) is not particularly limited, and conventionally known resins can be used. Examples of the tackifier resin (vii) include hydrocarbon-based tackifier resins, terpene-based resins, phenol-based resins, rosin-based resins, xylene resins, epoxy-based resins, polyamide-based resins, ketone-based resins, and elastomer-based resins. These may be used alone or in combination of two or more. Among these, hydrocarbon-based tackifier resins, terpene-based resins, and rosin-based resins are preferred in terms of improving adhesive properties. Furthermore, it is particularly preferred that the tackifier resin (vii) contains at least one of a hydrocarbon-based tackifier resin and a terpene-based resin in terms of the stability of the adhesive. Furthermore, terpene-based resins are particularly preferred in terms of maintaining a high bioplasticity and achieving compatibility with physical properties. The content of the tackifier resin is preferably 30% by weight or more, more preferably 50% by weight or more, and even more preferably 70% by weight or more of the total tackifier resin.

[0127] Examples of the hydrocarbon tackifying resin include various hydrocarbon 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. Commercially available products include "FTR6100," "FTR6110," and "FTR6125" manufactured by Mitsui Chemicals, Inc.

[0128] Examples of the terpene resin include terpene resin, terpene phenol resin, and aromatic-modified terpene resin. Specific examples include α-pinene polymer, β-pinene polymer, dipentene polymer, and terpene resins obtained by modifying these polymers with phenol, aromatic, hydrogen, or hydrocarbon. Terpene resins are preferred because they tend to have high adhesive strength after 24 hours of application, and terpene phenol resins are preferred because they have high adhesive strength to olefins. Commercially available products include "YS Polystar S145," "YS Resin PX1000," "YS Resin PX1250," "YS Polystar T145," "YS Resin TO115," "YS Polystar U130," and "Clearon P125," all manufactured by Yasuhara Chemical Co., Ltd.

[0129] Examples of the phenolic resin that can be used include condensates of formaldehyde with various phenols such as phenol, m-cresol, 3,5-xylenol, p-alkylphenol, and resorcinol. Other examples include resols obtained by subjecting the phenols and formaldehyde to an addition reaction in the presence of an alkali catalyst, novolaks obtained by subjecting the phenols and formaldehyde to a condensation reaction in the presence of an acid catalyst, and rosin-modified phenolic resins obtained by subjecting rosins, such as unmodified or modified rosin or derivatives thereof, to addition with phenol in the presence of an acid catalyst, followed by thermal polymerization.

[0130] Examples of the rosin resin include rosin resin, polymerized rosin resin, hydrogenated rosin resin, rosin ester resin, hydrogenated rosin ester resin, rosin phenolic resin, polymerized rosin ester, etc. Specific examples include unmodified rosins (raw rosins) such as gum rosin, wood rosin, and tall oil rosin, modified rosins obtained by hydrogenating, disproportionating, polymerizing, or otherwise chemically modifying these, and derivatives of these. Commercially available products include "Harie Star TF," "Harlitack 8LJA," "Harlitack PH," "Harlitack FK100," and "Harlitack PCJ," manufactured by Harima Chemicals Co., Ltd.

[0131] The tackifier resin (vii) preferably has an acid value of 30 mgKOH / g or less, particularly 10 mgKOH / g or less, further preferably 3 mgKOH / g or less, and particularly preferably 1 mgKOH / g or less. When multiple types of tackifier resins are used in combination, the average of their acid values ​​is preferably within the above range.

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

[0133] In the present invention, the tackifier resin (vii) is preferably a plant-derived resin in order to maintain a high bioplasticity of the entire PSA. Examples of plant-derived tackifier resins include terpene resins and rosin resins.

[0134] The content of the tackifier resin (vii) is preferably 2 to 100 parts by weight, more preferably 5 to 80 parts by weight, even 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, relative to 100 parts by weight of the polyester resin (i) or (ii). If the content is too high, the pressure-sensitive adhesive layer tends to become too hard and adhesion tends to decrease, whereas if the content is too low, the effect of adding the resin tends to be difficult to obtain.

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

[0136] The pressure-sensitive adhesive of the present invention is obtained by crosslinking the pressure-sensitive adhesive composition. Furthermore, the pressure-sensitive adhesive of the present invention preferably has a bioplasticity of 60% or more, more preferably 65% ​​or more, even more preferably 70% or more, and particularly preferably 80% or more. The bioplasticity of the pressure-sensitive adhesive can be adjusted by adjusting the types and amounts of the polyester resins (i) and (ii) and other blending components. The bioplastic degree of the PSA can be calculated as a weighted average of the bioplastic degree of the polyester resin determined by the above-mentioned method and the proportion of bio-derived carbon in each of the other components.

[0137] The bioplasticity of the pressure-sensitive adhesive can also be measured by the above-mentioned method using NMR or a method based on ASTM D-6866 [measurement of natural radioactive carbon (C-14) concentration].

[0138] The pressure-sensitive adhesive of the present invention is a pressure-sensitive adhesive obtained by crosslinking a pressure-sensitive adhesive composition, and has an adhesive strength (α) under the following conditions of 1 N / 25 mm or more, more preferably 5 to 100 N / 25 mm, even more preferably 7 to 50 N / 25 mm, and particularly preferably 9 to 30 N / 25 mm. If the adhesive strength is too small, the adhesion reliability decreases. Adhesive strength (α): When an adhesive sheet is formed on a substrate with an adhesive layer made of an adhesive, it is attached to a SUS-BA plate substrate and left to stand for 30 minutes in an environment of 23°C and 50% RH, after which the 180-degree peel strength (N / 25 mm) is measured at a peel speed of 300 mm / min against the substrate.

[0139] The pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive, and the pressure-sensitive adhesive layer is preferably formed on one or both sides of a supporting substrate. In the present invention, the term "sheet" is used to include "film" and "tape."

[0140] <Adhesive sheet> The pressure-sensitive adhesive sheet can be produced, for example, as follows. Such a pressure-sensitive adhesive sheet can be produced according to a known general method for producing a pressure-sensitive adhesive sheet. For example, the pressure-sensitive adhesive composition is applied to a substrate, followed by drying, and a release sheet is attached to the surface of the pressure-sensitive adhesive composition layer on the opposite side, followed by curing as necessary, to obtain the pressure-sensitive adhesive sheet of the present invention having a pressure-sensitive adhesive layer containing a pressure-sensitive adhesive on a substrate.

[0141] Alternatively, the pressure-sensitive adhesive sheet of the present invention can be obtained by coating the pressure-sensitive adhesive composition on a release sheet, drying the composition, laminating a substrate on the opposite side of the pressure-sensitive adhesive composition layer, and optionally curing the coated sheet.

[0142] Alternatively, a substrate-less double-sided PSA sheet can be produced by forming a PSA layer on a release sheet and then laminating another release sheet to the opposite side of the PSA layer.

[0143] When using the obtained pressure-sensitive adhesive sheet or substrate-less double-sided pressure-sensitive adhesive sheet, the release sheet is peeled off from the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer is attached to an adherend.

[0144] Examples of the 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; polyethylene fluoride resins such as polyvinyl fluoride, polyvinylidene fluoride, and polyethylene fluoride; 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 cellulose triacetate 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 and the like; metal foils of aluminum, copper, and iron; paper such as fine paper and glassine paper; and woven and nonwoven fabrics made of glass fiber, natural fiber, synthetic fiber, and the like. These substrates can be used as a single layer or as a multi-layer structure in which two or more types are laminated.

[0145] Among these, substrates made of polyethylene terephthalate and polyimide are particularly preferred, with polyethylene terephthalate being particularly preferred in terms of its excellent adhesiveness to pressure-sensitive adhesives.

[0146] The substrate may also be a foam substrate, such as a foam sheet made of a synthetic resin foam such as polyurethane foam, polyethylene foam, polyacrylate foam, etc. Among these, polyethylene foam and polyacrylate foam are preferred because they have an excellent balance between conformability to the adherend and adhesive strength.

[0147] The thickness of the substrate is, for example, preferably from 1 to 1000 μm, particularly preferably from 2 to 500 μm, and further preferably from 3 to 300 μm.

[0148] As the release sheet, for example, a sheet made of any of the various synthetic resins exemplified above as the substrate, paper, cloth, nonwoven fabric, etc. that has been subjected to a release treatment can be used. As the release sheet, it is preferable to use a silicone-based release sheet.

[0149] The pressure-sensitive adhesive composition may be applied using, for example, a gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, bar coater, knife coater, spray coater, comma coater, or the like.

[0150] The conditions for the aging treatment are generally room temperature (23°C) to 70°C, and the time is generally 1 to 30 days. Specifically, the treatment may be carried out under conditions such as 1 to 20 days at 23°C, preferably 3 to 14 days at 23°C, or 1 to 10 days at 40°C.

[0151] As for 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 pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet and substrate-less double-sided pressure-sensitive 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 the pressure-sensitive adhesive layer is too thin, the adhesive strength tends to decrease, while if it is too thick, it becomes difficult to apply uniformly and problems such as air bubbles entering the coating film tend to occur. In addition, when considering impact absorption, a thickness of 50 μm or more is preferable.

[0153] The thickness of the adhesive layer is determined by subtracting the measured thickness of the components other than the adhesive layer from the measured thickness of the entire adhesive sheet using a Mitutoyo ID-C112B.

[0154] The gel fraction of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is preferably 10% by weight or more, particularly preferably 20 to 80% by weight, even more preferably 25 to 70% by weight, and especially preferably 27 to 45% by weight, from the viewpoints of durability and adhesive strength. If the gel fraction is too low, the cohesive strength tends to decrease, resulting in a decrease in holding power. However, if the gel fraction is too high, the cohesive strength tends to increase, resulting in a decrease in adhesive strength.

[0155] The gel fraction is an index of the degree of crosslinking and is calculated, for example, by the following method. That is, a pressure-sensitive adhesive sheet (without a release sheet) consisting of a substrate polymer sheet (e.g., a PET film) on which a pressure-sensitive adhesive layer is formed is wrapped in a 200-mesh SUS wire netting and immersed in toluene at 23°C for 24 hours, and the gel fraction is calculated as the weight percentage of the insoluble pressure-sensitive adhesive component remaining in the wire netting after immersion relative to the weight of the pressure-sensitive adhesive component before immersion, excluding the weight of the substrate.

[0156] Furthermore, such a PSA sheet may be protected by providing a release sheet on the outer side of the PSA layer, if necessary. In a PSA sheet in which the PSA layer is formed on one side of a substrate, the PSA layer can be protected by applying a release treatment to the side of the substrate opposite the PSA layer, thereby utilizing the release-treated surface.

[0157] The pressure-sensitive adhesive of the present invention can be used to bond various components, and in particular, can be used as a single-sided or double-sided pressure-sensitive adhesive sheet for bonding optical components, or as a single-sided or double-sided pressure-sensitive adhesive sheet for fixing components of portable electronic devices or electronic components. [Example]

[0158] The present invention will be explained in more detail below by way of examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention. In the examples, "parts" and "%" are by weight.

[0159] In the examples below, the bioplasticity of the polyester resin, the ester group concentration, the heat of crystalline fusion, the weight average molecular weight, the glass transition temperature, the acid value, and the gel fraction of the adhesive were measured according to the methods described above.

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

[0161] [Production Example 1: Production of Polyester Resin (i-1)] Thermometer, stirrer, distillation column, nitrogen inlet tube and vacuum equipment equipped reactor, polycarboxylic acids (a), sebacic acid 17.8 parts (0.45 mol), hydrodistilled dimer acid (Croda, "Pripol 1009") 61.4 parts (0.55 mol), polyol component (b), ethylene glycol 20.7 parts (1.7 mol) and trimethylolpropane 0.2 parts (0.0065 mol), catalyst, tetrabutyl titanate 0.01 parts were charged, the internal temperature was gradually increased to 250 ° C., and an esterification reaction was carried out over 4 hours. Then, the internal temperature was increased to 260 ° C., and tetrabutyl titanate 0.01 parts were charged as a catalyst, the pressure was reduced to 1.33 hPa, and the polymerization reaction was carried out over 3 hours, producing polyester resin (i-1). The resulting polyester resin (i-1) had a bioplasticity of 92%, an ester group concentration of 4.64 mmol / g, a heat of fusion of 0 J / g, a weight-average molecular weight of 58,000, a glass transition temperature (Tg) of -50°C, and an acid value of 0.4 mg KOH / g. The plant-derived raw materials in Production Example 1 were sebacic acid and hydrodistilled dimer acid, and the content of these relative to the polyester resin (i-1) was 86%.

[0162] [Production Example 2: Production of Polyester Resin (i-2)] Thermometer, stirrer, distillation column, nitrogen inlet tube and vacuum equipment equipped reactor, as polycarboxylic acids (a), hydrodistilled dimer acid (manufactured by Croda, "Pripol 1009") 84.3 parts (1.00 mol), as polyol component (b), ethylene glycol 15.6 parts (1.7 mol) and trimethylolpropane 0.1 parts (0.0065 mol), as catalyst, tetrabutyl titanate 0.01 parts were charged, the internal temperature was gradually increased to 250 ° C., and the esterification reaction was carried out over 4 hours. Then, the internal temperature was increased to 260 ° C., and tetrabutyl titanate 0.01 parts was charged as a catalyst, the pressure was reduced to 1.33 hPa, and the polymerization reaction was carried out over 3 hours, producing polyester resin (i-2). The resulting polyester resin (i-2) had a bioplasticity of 95%, an ester group concentration of 3.36 mmol / g, a heat of fusion of 0 J / g, a weight-average molecular weight of 72,000, a glass transition temperature (Tg) of -47°C, and an acid value of 0.3 mg KOH / g. The plant-derived raw material in Production Example 2 was a hydrodistilled dimer acid, and its content relative to the polyester resin (i-2) was 90%.

[0163] [Production Example 3: Production of Polyester Resin (i-3)] Thermometer, stirrer, distillation column, nitrogen inlet tube and vacuum equipment equipped reactor, as polycarboxylic acids (a), hydrodistilled dimer acid (manufactured by Croda, "Pripol 1009") 80.6 parts (1.00 mol), as polyol component (b), 19.1 parts (1.5 mol) of 1,4-butanediol and 0.3 parts (0.015 mol) of trimethylolpropane, as a catalyst, tetrabutyl titanate 0.01 parts were charged, the internal temperature was gradually increased to 250 ° C., and an esterification reaction was carried out over 4 hours. Then, the internal temperature was increased to 260 ° C., and 0.01 parts of tetrabutyl titanate were charged as a catalyst, the pressure was reduced to 1.33 hPa, and the polymerization reaction was carried out over 3 hours to produce polyester resin (i-3). The resulting polyester resin (i-3) had a bioplasticity of 86%, an ester group concentration of 3.21 mmol / g, a heat of fusion of 0 J / g, a weight-average molecular weight of 71,000, a glass transition temperature (Tg) of -52°C, and an acid value of 0.3 mg KOH / g. The plant-derived raw material in Production Example 3 was a hydrodistilled dimer acid, and its content relative to the polyester resin (i-3) was 86%.

[0164] [Production Example 4: Production of Polyester Resin (i-4)] Thermometer, stirrer, distillation column, nitrogen inlet tube and vacuum equipment equipped reactor, as polycarboxylic acids (a), hydrodistilled dimer acid (manufactured by Croda, "Pripol 1009") 80.3 parts (1.00 mol), as polyol component (b), ethylene glycol 7.9 parts (0.90 mol), neopentyl glycol 11.7 parts (0.80 mol) and trimethylolpropane 0.1 parts (0.0065 mol), as a catalyst, tetrabutyl titanate 0.01 parts were charged, the internal temperature was gradually increased to 250 ° C., and an esterification reaction was carried out over 4 hours. Then, the internal temperature was increased to 260 ° C., and as a catalyst, tetrabutyl titanate 0.01 parts were charged, the pressure was reduced to 1.33 hPa, and the polymerization reaction was carried out over 3 hours, producing polyester resin (i-4). The resulting polyester resin (i-4) had a bioplasticity of 91%, an ester group concentration of 3.25 mmol / g, a heat of fusion of 0 J / g, a weight-average molecular weight of 72,000, a glass transition temperature (Tg) of -47°C, and an acid value of 0.2 mg KOH / g. The plant-derived raw material in Production Example 4 was a hydrodistilled dimer acid, and its content relative to the polyester resin (i-4) was 87%.

[0165] [Production Example 5: Production of Polyester Resin (i-5)] Thermometer, stirrer, distillation column, nitrogen inlet tube and vacuum equipment equipped reactor, polycarboxylic acids (a), sebacic acid 17.0 parts (0.45 mol), hydrodistilled dimer acid (Croda, "Pripol 1009") 58.5 parts (0.55 mol), polyol component (b), ethylene glycol 24.3 parts (2.1 mol) and trimethylolpropane 0.2 parts (0.0065 mol), catalyst, tetrabutyl titanate 0.01 parts were charged, the internal temperature was gradually increased to 250 ° C., and an esterification reaction was carried out over 4 hours. Then, the internal temperature was increased to 260 ° C., and tetrabutyl titanate 0.01 parts were charged as a catalyst, the pressure was reduced to 1.33 hPa, and the polymerization reaction was carried out over 3 hours, producing polyester resin (i-5). The resulting polyester resin (i-5) had a bioplasticity of 92%, an ester group concentration of 4.64 mmol / g, a heat of fusion of 0 J / g, a weight-average molecular weight of 97,000, a glass transition temperature (Tg) of -50°C, and an acid value of 0.1 mg KOH / g. The plant-derived raw materials in Production Example 5 were sebacic acid and hydrodistilled dimer acid, and the content of these in the polyester resin (i-5) was 86%.

[0166] [Production Example 6: Production of Polyester Resin (i-6)] Thermometer, stirrer, distillation column, nitrogen inlet tube and vacuum equipment equipped reactor, as polycarboxylic acids (a), hydrodistilled dimer acid (manufactured by Croda, "Pripol 1009") 84.3 parts (1.00 mol), as polyol component (b), ethylene glycol 15.6 parts (1.7 mol) and trimethylolpropane 0.1 parts (0.0065 mol), as catalyst, tetrabutyl titanate 0.01 parts were charged, the internal temperature was gradually increased to 250 ° C., and the esterification reaction was carried out over 4 hours. Then, the internal temperature was increased to 260 ° C., and tetrabutyl titanate 0.01 parts was charged as a catalyst, the pressure was reduced to 1.33 hPa, and the polymerization reaction was carried out over 3 hours, producing polyester resin (i-6). The resulting polyester resin (i-6) had a bioplasticity of 95%, an ester group concentration of 3.36 mmol / g, a heat of fusion of 0 J / g, a weight-average molecular weight of 88,000, a glass transition temperature (Tg) of -47°C, and an acid value of 0.1 mg KOH / g. The plant-derived raw material in Production Example 6 was a hydrodistilled dimer acid, and its content relative to the polyester resin (i-6) was 90%.

[0167] Comparative Production Example 1: Production of Polyester Resin (i'-1) Thermometer, stirrer, distillation column, nitrogen inlet tube and vacuum equipment equipped reactor, as polycarboxylic acids (a), hydrodistilled dimer acid (manufactured by Croda, "Pripol 1009") 49.2 parts (1.00 mol), as polyol component (b), dimer diol (manufactured by Croda, "Pripol 2033") 50.8 parts (1.09 mol), as a catalyst, tetrabutyl titanate 0.01 parts were charged, the internal temperature was gradually increased to 200 ° C., and the esterification reaction was carried out over 4 hours. Then, the internal temperature was increased to 240 ° C., and 0.01 parts of tetrabutyl titanate were charged as a catalyst, the pressure was reduced to 1.33 hPa, and the polymerization reaction was carried out over 3 hours, producing polyester resin (i'-1). The obtained polyester resin (i'-1) had a bioplasticity of 100%, an ester group concentration of 1.78 mmol / g, a heat of fusion of crystalline 0 J / g, a weight-average molecular weight of 33,000, a glass transition temperature (Tg) of -50°C, and an acid value of 0.1 mg KOH / g. The plant-derived raw materials in Comparative Production Example 1 were hydrodistilled dimer acid and dimer diol, and the content of these relative to the polyester resin (i'-1) was 100%.

[0168] Comparative Production Example 2: Production of Polyester Resin (i'-2) A reactor equipped with a heater, a thermometer, a stirrer, a rectification column, a nitrogen inlet tube, and a vacuum device was charged with 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 parts (0.013 mol) of trimethylolpropane as polyol components (b), and 0.01 parts of tetrabutyl titanate as a catalyst. The internal temperature was gradually increased to 250°C, and an esterification reaction was carried out over 4 hours. Thereafter, the internal temperature was raised to 260° C., 0.01 parts 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 obtained polyester resin (i'-2) had a bioplasticity of 56%, an ester group concentration of 7.7 mmol / g, a heat of fusion of crystals of 0 J / g, a weight-average molecular weight of 80,000, a glass transition temperature (Tg) of -49°C, and an acid value of 0.4 mg KOH / g. The plant-derived raw material in Comparative Production Example 2 was sebacic acid, and its content relative to the polyester resin (i'-2) was 52%.

[0169] Comparative Production Example 3: Production of Polyester Resin (i'-3) A reactor equipped with a thermometer, a stirrer, a distillation column, a nitrogen inlet tube, and a vacuum device was charged with 17.8 parts (0.45 mol) of sebacic acid as polycarboxylic acid (a), 61.2 parts (0.55 mol) of hydrodistilled dimer acid (manufactured by Croda, "Pripol 1006"), 20.6 parts (1.387 mol) of 1,3-propanediol as polyol component (b), and 0.3 parts (0.013 mol) of trimethylolpropane, 0.01 parts of tetrabutyl titanate as catalyst, and the temperature was gradually increased to 250 ° C., and the esterification reaction was carried out over 4 hours. Then, the internal temperature was increased to 260 ° C., and 0.01 parts of tetrabutyl titanate as catalyst was charged, and the pressure was reduced to 1.33 hPa, and the polymerization reaction was carried out over 3 hours to produce polyester resin (i'-3). The obtained polyester resin (i'-3) had a bioplasticity of 100%, an ester group concentration of 4.49 mmol / g, a heat of crystalline fusion of 0 J / g, a weight-average molecular weight of 112,000, a glass transition temperature (Tg) of -56°C, and an acid value of 0.5 mg KOH / g. The plant-derived raw materials of Comparative Production Example 3 were hydrodistilled dimer acid, sebacic acid, and 1,3-propanediol, and the content of hydrodistilled dimer acid and sebacic acid relative to the polyester resin (i'-3) was 83%.

[0170] Comparative Production Example 4: Production of Polyester Resin (i'-4) In a reactor equipped with a thermometer, a stirrer, a distillation column, a nitrogen inlet tube, and a vacuum device, 84.1 parts (1.00 mol) of hydrodistilled dimer acid (manufactured by Croda, "Pripol 1006") as polycarboxylic acids (a), 15.6 parts (1.387 mol) of 1,3-propanediol as polyol component (b), and 0.3 parts (0.013 mol) of trimethylolpropane, 0.01 parts of tetrabutyl titanate as a catalyst were charged, and the internal temperature was gradually increased to 250 ° C., and an esterification reaction was carried out over 4 hours. Then, the internal temperature was increased to 260 ° C., and 0.01 parts of tetrabutyl titanate were charged as a catalyst, and the pressure was reduced to 1.33 hPa, and the polymerization reaction was carried out over 3 hours to produce polyester resin (i'-4). The obtained polyester resin (i'-4) had a bioplasticity of 100%, an ester group concentration of 3.28 mmol / g, a heat of crystalline fusion of 0 J / g, a weight-average molecular weight of 157,000, a glass transition temperature (Tg) of -52°C, and an acid value of 0.8 mg KOH / g. The plant-derived raw materials of Comparative Production Example 4 were hydrodistilled dimer acid and 1,3-propanediol, and the content of hydrodistilled dimer acid relative 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] The polyester resins produced in the above production examples were examined for bioplasticity, ester group concentration, and heat of crystalline fusion. As a result, (i-1) to (i-6) all satisfied the ranges specified in the present invention, and can be used as the polyester resin (i) or (ii) used in the pressure-sensitive adhesive composition of the present invention.

[0175] On the other hand, polyester resin (i'-2), which is a common polyester resin for adhesives, has a bioplasticity of about 56%, which is insufficient for reducing the burden on the environment.

[0176] Next, prior to preparing the pressure-sensitive adhesive composition, the following components were prepared. [Hydrolysis inhibitor (iii)] Carbodiimide compound (iii-1): "Carbodilite V-09GB" (Nisshinbo Chemical Co., Ltd.) [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 compounds (v-1): "Orgatics ZC-150" (Matsumoto Fine Chemical Co., Ltd.) (diluted with acetylacetone to a solids concentration of 1%) [Antioxidants (vi)] Hindered phenolic antioxidant (vi-1): "IRGANOX 1010" (BASF) [Tackifying resin (vii)] Aromatic hydrocarbon resin (vii-1): "FTR6100" (Mitsui Chemicals) (softening point: 95°C, acid value: less than 0.1 mgKOH / g) Bioplastic content: 0% Polymerized rosin ester (vii-2): "Haritack PCJ" (Harima Chemicals Co., Ltd.) (softening point: 118-128°C, acid value: 16 mg KOH / g or less) Bioplastic content: 88% Special rosin ester (vii-3): "Super Ester A-100" (Arakawa Chemical Co., Ltd.) (softening point: 100°C, acid value: 10 mgKOH / g or less) Bioplastic content: 99% Aromatic terpene (vii-4): "YS Resin TO115" (Yasuhara Chemical Co., Ltd.) (softening point: 115°C, acid value: 0 mgKOH / g) Bioplastic content: 70% or more Terpene resin (vii-5): "YS Resin PX1000" (Yasuhara Chemical Co., Ltd.) (softening point: 110°C, acid value: 0 mgKOH / g) Bioplastic content: 90% or more

[0177] Next, the polyester resins (i-1 to i-6 and i'-1 to i'-4) obtained above were used to prepare pressure-sensitive adhesive compositions according to the following Examples and Comparative Examples, and pressure-sensitive adhesive sheets were fabricated.

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

[0179] [Examples 2 to 14, Comparative Examples 1 to 7] A pressure-sensitive adhesive composition was prepared and a pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1, except that the ingredients were blended as shown in Table 3 below.

[0180] [Table 3]

[0181] The following evaluations were carried out on the obtained pressure-sensitive adhesive sheets of Examples 1 to 14 and Comparative Examples 1 to 7. The evaluation results are shown in Table 4 below.

[0182] <Adhesive strength (peel strength) (against SUS-BA)> A SUS-BA plate was prepared as the adherend. The pressure-sensitive adhesive sheet obtained above was cut to 25 mm x 200 mm in an environment of 23 °C and 50% RH, after which the release film was peeled off, and the pressure-sensitive adhesive layer side was placed against the SUS-BA plate, and a 2 kg roller was pressed back and forth to adhere it. After leaving it in the same atmosphere for 30 minutes, the 180-degree peel strength (N / 25 mm) was measured at a peel speed of 300 mm / min using an autograph (Shimadzu Corporation, Autograph AGS-H 500N) and evaluated according to the following criteria. (Evaluation criteria) ◎...5N / 25mm or more. ○···More than 1N / 25mm, less than 5N / 25mm. ×...Less than 1N / 25mm.

[0183] <Adhesive strength after 24 hours (peel strength after 24 hours)> A SUS-BA plate was prepared as the adherend. The pressure-sensitive adhesive sheet obtained above was cut to 25 mm x 200 mm in an environment of 23°C and 50% RH, after which the release film was peeled off, and the pressure-sensitive adhesive layer side was placed against the SUS-BA plate, and a 2 kg roller was pressed back and forth to adhere the sheet. After leaving the sheet in the same atmosphere for 24 hours, the 180° peel strength (N / 25 mm) was measured at a peel speed of 300 mm / min using an autograph (Shimadzu Corporation, Autograph AGS-H 500N) and evaluated according to the following criteria. (Evaluation criteria) ◎...20N / 25mm or more. ○···More than 13N / 25mm, less than 20N / 25mm. ×Less than 13N / 25mm.

[0184] <Adhesive strength (peel strength) (against PP)> A polypropylene (PP) plate (Nippon Test Panel Co., Ltd., PP 2.0 × 70 × 150 mm) was prepared as the adherend. The pressure-sensitive adhesive sheet obtained above was cut to 25 mm × 200 mm in an environment of 23 ° C and 50% RH, and the release film was peeled off. The pressure-sensitive adhesive layer side was placed against a polypropylene (PP) plate, and a 2 kg roller was pressed back and forth to adhere the sheet. After leaving the sheet to stand for 30 minutes in the same atmosphere, the 180-degree peel strength (N / 25 mm) was measured at a peel speed of 300 mm / min using an autograph (Shimadzu Corporation, Autograph AGS-H 500N) and evaluated according to the following criteria. (Evaluation criteria) ◎...10N / 25mm or more. ○···More than 6N / 25mm, less than 10N / 25mm. ×Less than 6N / 25mm.

[0185] <Holding force (cohesive force)> The pressure-sensitive adhesive sheet obtained above was applied to a SUS304 substrate in accordance with JIS Z-0237, with an area of ​​25 mm x 25 mm, and then left to stand at 80°C for 20 minutes. A load of 1 kg was then applied and the time until the sheet fell off was measured, or for sheets that had not fallen off after 24 hours of standing, the displacement after 24 hours was measured and evaluated according to the following criteria. (Evaluation criteria) ○...It did not fall off even after being left standing for 24 hours. ×: The sample fell off after being left standing for 24 hours.

[0186] <Mark resistance> The pressure-sensitive adhesive composition was applied to a polyethylene terephthalate (PET) film (thickness: 38 μm) as a substrate so that the thickness after drying would be approximately 25 μm, and then dried for 3 minutes at 100° C. to form a pressure-sensitive adhesive layer. A release-treated PET film (release film) was then attached to the pressure-sensitive adhesive layer, and a 2 kg roller was placed on top of the release film and stopped for 10 seconds, after which the pressure-sensitive adhesive layer was visually observed and evaluated according to the following criteria. (Evaluation criteria) ○···No change. × There are dents where the roller was placed.

[0187] <Workability> The adhesive sheet obtained above was cut into a width of 25 mm with a cutter knife, and adhesion of the adhesive to the blade of the cutter knife was visually observed and evaluated according to the following criteria. (Evaluation criteria) ○···Glue did not stick to the blade. ×...Glue got on the blade.

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

[0189] [Table 4]

[0190] The results in Table 4 show that the pressure-sensitive adhesive sheets of Examples 1 to 14 had the desired adhesive properties not only on metal adherends but also on adherends that are difficult to adhere to, such as polyolefin-based resins, and exhibited an excellent balance between adhesive strength and holding power. Furthermore, even when narrowed, the pressure-sensitive adhesive sheets of Examples 1 to 14 exhibited excellent resistance to dents during production, excellent processability as pressure-sensitive adhesive sheets, and excellent processability and transparency during lamination. Furthermore, it can be seen that the inclusion of a tackifier resin resulted in even better adhesive properties, and even better adhesive properties over time. In contrast, the pressure-sensitive adhesives of Comparative Examples 1 to 3, which used conventional polyester-based resins with a high bioplasticity, did not have satisfactory adhesive properties, and the pressure-sensitive adhesive layer was too soft, causing dents and exhibiting poor processability and transparency.Furthermore, the pressure-sensitive adhesives of Comparative Examples 1 and 3 to 7, which used polyester-based resins that did not use glycols with an even number of carbon atoms as the polyol component, exhibited insufficient adhesive strength to polyolefin resins and a poor balance between adhesive strength and holding power.

[0191] Although the above examples show specific embodiments of the present invention, the examples are merely illustrative and should not be construed as limiting. Various modifications that are obvious to those skilled in the art are intended to fall within the scope of the present invention. [Industrial Applicability]

[0192] The pressure-sensitive adhesive of the present invention uses environmentally friendly plant-derived raw materials, and even when a polyester-based resin with a high bioplasticity is used, it has good adhesive properties to various adherends such as metals and plastics, and has excellent processability, dent resistance, and transparency even when made narrower.It can be used as a single-sided or double-sided pressure-sensitive adhesive sheet used for bonding optical components, or as a single-sided or double-sided pressure-sensitive adhesive sheet for fixing components of portable electronic devices or electronic components.

Claims

1. A pressure-sensitive adhesive obtained by crosslinking a pressure-sensitive adhesive composition containing a polyester resin (i) having a structural moiety derived from a polyvalent carboxylic acid (a) and a structural moiety derived from a polyol component (b), and a tackifier resin (vii), the polyester-based resin (i) contains 60% by weight or more of a structural moiety derived from at least one selected from the group consisting of dimer acids, sebacic acids, and dimer diols, based on the polyester-based resin (i); As the polyol component (b), a glycol (b1) having an even number of carbon atoms (excluding dimer diol) ) the content of the glycol (b1) having an even number of carbon atoms is 10 to 100 mol % based on the total polyol component (b), The polyester resin (i) has an ester group concentration of 2 mmol / g or more and a weight average molecular weight of 71,000 to 500,000; A pressure-sensitive adhesive characterized by having an adhesive strength (α) of 1 N / 25 mm or more under the following conditions: Adhesive strength (α): When a pressure-sensitive adhesive sheet is formed on a substrate with a pressure-sensitive adhesive layer made of a pressure-sensitive adhesive, the sheet is attached to an adherend made of SUS-BA plate and allowed to stand for 30 minutes in an environment of 23°C and 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, wherein 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 polycarboxylic acid (a) contains 70 mol % or less of a linear carboxylic acid (a1).

4. The pressure-sensitive adhesive according to any one of claims 1 to 3, wherein the glycol (b1) having an even number of carbon atoms is a polyol having 4 or less carbon atoms.

5. The pressure-sensitive adhesive according to any one of claims 1 to 4, wherein the polyester resin (i) has an acid value of 10 mgKOH / g or less.

6. The pressure-sensitive adhesive according to any one of claims 1 to 5, wherein the polyester resin (i) has a bioplasticity of 60% or more.

7. A pressure-sensitive adhesive obtained by crosslinking a pressure-sensitive adhesive composition containing a polyester resin (ii) having a bioplasticity of 60% or more and a tackifier resin (vii), the polyester resin (ii) has a structural moiety derived from a polycarboxylic acid (a) and a structural moiety derived from a polyol component (b); As the polyol component (b), a glycol (b1) having an even number of carbon atoms (excluding dimer diol) ) the content of the glycol (b1) having an even number of carbon atoms is 10 to 100 mol % based on the total polyol component (b), The polyester resin (ii) has an ester group concentration of 2 mmol / g or more and a weight average molecular weight of 71,000 to 500,000; A pressure-sensitive adhesive characterized by having an adhesive strength (α) of 1 N / 25 mm or more under the following conditions: Adhesive strength (α): When a pressure-sensitive adhesive sheet is formed on a substrate with a pressure-sensitive adhesive layer made of a pressure-sensitive adhesive, the sheet is attached to an adherend made of SUS-BA plate and allowed to stand for 30 minutes in an environment of 23°C and 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.

8. The pressure-sensitive adhesive according to any one of claims 1 to 7, characterized in that the pressure-sensitive adhesive composition further contains a hydrolysis inhibitor (iii).

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 crosslinking agent (iv).

10. The pressure-sensitive adhesive according to any one of claims 1 to 9, characterized in that the bioplasticity is 60% or more.

11. The pressure-sensitive adhesive according to any one of claims 1 to 10, which is used for bonding members together.

12. A pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive according to any one of claims 1 to 11. An adhesive sheet.

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