JP7151410B2 - Hot melt adhesive with excellent transparency and chemical resistance - Google Patents

Description

The present invention relates to a crystalline polyester resin having transparency and chemical resistance. More particularly, it relates to a hot-melt adhesive containing a polyester resin composition having excellent transparency and chemical resistance.

Hot-melt adhesives containing crystalline polyester resins are excellent in water resistance, chemical resistance, etc., and can be used for adhesion without using solvents. However, since these hot melt adhesives are crystalline, it is difficult to obtain transparency. In order to improve the transparency, a method of lowering the degree of crystallinity is conceivable. However, lowering the degree of crystallinity also lowers the chemical resistance, making it a challenge to achieve both transparency and chemical resistance.

As a crystalline polyester resin, a method of copolymerizing polyalkylene glycol in polyester is known. However, in the polyether polyester block copolymer system, the blockiness is high, the mobility of the polyether portion is high at room temperature, and the crystallization of the polyester portion progresses over time, causing a problem of whitening (Patent Documents 1).

In the methods disclosed in Patent Documents 2 and 3, the results of the tetrachlorethylene immersion test at 50°C were good, but when the immersion test was repeatedly performed, there was a problem that appearance defects occurred due to insufficient chemical resistance. .

A method of blending a fatty acid metal salt with a polyester block copolymer has also been proposed (for example, Patent Document 4).

JP-A-7-70535 Japanese Patent Publication No. 59-2476 Japanese Patent Publication No. 63-54034 Japanese Patent Application Laid-Open No. 2001-164101

However, in the method disclosed in Patent Document 4, since an amorphous polyester is used for the soft segment, the fatty acid metal salt bleeds out over time, resulting in poor adhesiveness, resulting in a hot melt adhesive. There was a problem that it could not be applied.

In order to achieve the above object, the present inventors have made intensive studies and have come to propose the following invention. That is, the present invention is as follows.

A crystalline polyester resin composed of a polyvalent carboxylic acid component and a polyhydric alcohol component, containing 60 mol% or more of terephthalic acid when the polyvalent carboxylic acid component of the crystalline polyester resin is 100 mol%, and polyhydric When the alcohol component is 100 mol%, it contains 40 to 60 mol% of ethylene glycol, 40 to 60 mol% of 1,4-butanediol, 1 to 3.5 mol% of polyalkylene glycol, and 5 mol% of diethylene glycol. A crystalline polyester resin characterized by having a mol % or less and a melting point in the range of 120 to 140°C.

The crystalline polyester resin preferably has a specific gravity of 1.26 or higher and a glass transition temperature of 5° C. or lower.

A hot-melt adhesive containing the crystalline polyester resin according to any one of the above.

The polyester resin composition of the present invention relates to a hot-melt adhesive that has good adhesion to various plastic films and metals and has excellent transparency and chemical resistance.

FIG. 1 shows a schematic diagram of a curved sheet sample.

<Crystalline polyester resin>
The crystalline polyester resin used in the present invention is a polyester copolymerized from a polyhydric carboxylic acid component and a polyhydric alcohol component, and preferably has a dicarboxylic acid component and a glycol component as copolymerized components.

When the total polyvalent carboxylic acid component constituting the crystalline polyester resin of the present invention is 100 mol %, it is necessary that the terephthalic acid component is copolymerized in an amount of 60 mol % or more, preferably 62 mol % or more. Yes, more preferably 65 mol % or more. If the amount is too small, a polyester resin having excellent chemical resistance may not be obtained. Also, it is preferably 80 mol % or less, more preferably 75 mol % or less, and even more preferably 70 mol % or less. If it is too large, the crystallinity of the polyester resin may become high and the transparency may be lowered.

It is also preferable to copolymerize an adipic acid component as the polyvalent carboxylic acid component of the crystalline polyester resin. By copolymerizing the adipic acid component, it is expected that the glass transition temperature and melting point of the crystalline polyester resin will be lowered and the adhesiveness will be improved. The copolymerization ratio of the adipic acid component is preferably 10 mol% or more, more preferably 15 mol% or more, and still more preferably 18 mol% or more when the total polycarboxylic acid component is 100 mol%. is. If the amount is too small, the glass transition temperature and melting point may become high and the adhesiveness may be lowered. Also, it is preferably 40 mol % or less, more preferably 30 mol % or less, and still more preferably 23 mol % or less. If it is too large, the crystallinity of the crystallized polyester may deteriorate.

It is also preferable to copolymerize an isophthalic acid component as the polyvalent carboxylic acid component of the crystalline polyester resin. By copolymerizing the isophthalic acid component, it is expected that the melting point of the crystalline polyester resin will be lowered and the adhesiveness will be improved. The copolymerization ratio of the isophthalic acid component is preferably 5 mol% or more, more preferably 6 mol% or more, and still more preferably 8 mol% or more when the total polycarboxylic acid component is 100 mol%. is. When the amount is too small, the melting point becomes high and the adhesiveness may deteriorate. Also, it is preferably 20 mol % or less, more preferably 15 mol % or less, and still more preferably 12 mol % or less. If it is too large, the crystallinity of the crystallized polyester may deteriorate.

The polyvalent carboxylic acid component preferably contains terephthalic acid, isophthalic acid and adipic acid, and the total amount of terephthalic acid, isophthalic acid and adipic acid is preferably 95 mol% or more, more preferably 98 mol. % or more, more preferably 99 mol % or more, even 100 mol %. The ratio (molar ratio) of the total amount of terephthalic acid to isophthalic acid and adipic acid is preferably terephthalic acid/(isophthalic acid + adipic acid) = 1.5 to 4/1, more preferably 1.6. to 3/1, more preferably 1.8 to 2.5/1. The ratio (molar ratio) of isophthalic acid and adipic acid is preferably isophthalic acid/adipic acid=1/1 to 3, more preferably 1/1.5 to 2.5. Satisfying the above range can improve the adhesiveness of the crystalline polyester resin.

Specific examples of other polycarboxylic acids are not particularly limited, but aromatic dicarboxylic acids include orthophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 5-sodiumsulfoisophthalic acid, 5-lithiumsulfoisophthalic acid, 5-sodium sulfoterephthalic acid, 4,4'-diphenylmethanedicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 4,4'-stilbenedicarboxylic acid, Examples include p-oxybenzoic acid, p-(hydroxyethoxy)benzoic acid, β-hydroxynaphthoic acid, and the like, and these can be used alone or in combination of two or more. As the aliphatic dicarboxylic acid, either a linear aliphatic dicarboxylic acid or a branched aliphatic dicarboxylic acid may be used. of aliphatic dicarboxylic acids are preferred. Specific examples include, but are not limited to, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, dimer acid, and the like, and these can be used alone or in combination of two or more. Unsaturated alicyclic dicarboxylic acids include fumaric acid, maleic acid, itaconic acid, hexahydrophthalic acid, tetrahydrophthalic acid and the like. As the alicyclic dicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid and the like can also be used. Examples of trivalent or higher polycarboxylic acid components include polyvalent carboxylic acids such as trimellitic acid, pyromellitic acid, benzophenonetetracarboxylic acid, biphenylsulfonetetracarboxylic acid and biphenyltetracarboxylic acid, and their anhydrides. can. These dicarboxylic acid components and polycarboxylic acid components having a valence of 3 or more may be used alone or in combination of two or more. The copolymerization ratio of these polyvalent carboxylic acid components is preferably 5 mol % or less, more preferably 2 mol % or less when the total polyvalent carboxylic acid component of the crystalline polyester resin is taken as 100 mol %. More preferably, it is 1 mol % or less, and 0 mol % is acceptable.

As the polyhydric alcohol component constituting the crystalline polyester resin of the present invention, it is necessary to use 1,4-butanediol from the viewpoint of heat resistance and crystallinity. The amount of 1,4-butanediol copolymerized must be 35 mol% or more, preferably 40 mol% or more, and more preferably 100 mol% of the total polyhydric alcohol component. It is 45 mol % or more, more preferably 50 mol % or more. If the amount is too small, the chemical resistance, adhesiveness, flexibility and crystallinity may deteriorate. Further, the copolymerization amount of 1,4-butanediol must be 60 mol% or less, preferably 57 mol% or less, when the total amount of the polyhydric alcohol component is 100 mol%, More preferably, it is 55 mol % or less. If it is too large, the transparency may be lowered.

It is also necessary to copolymerize an ethylene glycol component as the polyhydric alcohol component of the crystalline polyester resin. Copolymerization of the ethylene glycol component is expected to lower the crystallinity of the crystalline polyester resin and improve the transparency. When the total polyhydric alcohol component is 100 mol%, the copolymerization ratio of the ethylene glycol component must be 35 mol% or more, preferably 40 mol% or more, and more preferably 43 mol% or more. and more preferably 45 mol % or more. If the amount is too small, the crystallinity may increase and the transparency may decrease. Further, it is required to be 60 mol % or less, preferably 55 mol % or less, more preferably 50 mol % or less. If it is too large, the crystallinity of the crystallized polyester resin may be lowered, and the chemical resistance, adhesiveness and flexibility may be lowered.

It is necessary to copolymerize a polyalkylene glycol component as the polyhydric alcohol component of the crystalline polyester resin. By copolymerizing the polyalkylene glycol component, it is expected that the glass transition temperature of the crystalline polyester resin will be lowered, and the adhesiveness and flexibility will be improved. Examples of polyalkylene glycol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol and the like, with polytetramethylene glycol being preferred. The amount of copolymerization of the polyalkylene glycol component is required to be 1 mol% or more, preferably 1.5 mol% or more, more preferably 2 mol%, when the total polyhydric alcohol component is 100 mol%. mol% or more. If the amount is too small, the glass transition temperature may become high and the flexibility may decrease. Also, it must be 3.5 mol % or less, preferably 2.5 mol % or less. If the amount is too large, the crystallinity of the crystallized polyester resin may be lowered and the chemical resistance may be lowered.

As the polyhydric alcohol component of the crystalline polyester resin, the copolymerization ratio of the diethylene glycol component must be 5 mol% or less, preferably 4 mol% or less, when the total polyhydric alcohol component is 100 mol%. It is preferably 2 mol % or less, still more preferably 1 mol % or less, and may even be 0 mol %. If the amount is too large, the crystallinity of the crystallized polyester resin may be lowered and the chemical resistance may be lowered.

Examples of other polyhydric alcohol components include, but are not limited to, 1,2-propylene glycol, 1,3-propylene glycol, 1,5-pentanediol, 3-methylpentanediol, 1,6-hexanediol, 1,9-nonanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, diethylene glycol, triethylene glycol, neopentyl glycol, cyclohexanedimethanol , tricyclodecanedimethanol, ethylene oxide and/or propylene oxide adducts of bisphenol A, and the like, and these can be used alone or in combination of two or more. The copolymerization ratio of these polyhydric alcohol components is preferably 5 mol% or less, more preferably 3 mol% or less, when the total polyhydric alcohol component of the crystalline polyester resin is 100 mol%. It is more preferably 1 mol % or less, and may be 0 mol %.

Furthermore, polyhydric alcohol components having tri- or higher functionalities such as glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol can also be used. In that case, the copolymerization amount of the polyhydric alcohol having three or more functional groups is preferably 5 mol% or less, more preferably 2 mol% or less, and 1 mol, when the total polyhydric alcohol component is 100 mol%. % or less, and may be 0 mol %. If it is too large, the mechanical properties such as elongation at break of the coating film may be lowered, and gelation may occur during polymerization.

As the polyhydric alcohol component, the total amount of ethylene glycol, 1,4-butanediol and polyalkylene glycol is preferably 90 mol% or more, more preferably 95 mol% or more, still more preferably 97 mol%. 99 mol % or more is particularly preferable, and 100 mol % is acceptable. The ratio (molar ratio) of ethylene glycol and 1,4-butanediol is preferably ethylene glycol/1,4-butanediol = 20 to 60/80 to 40, more preferably 30 to 50/70 to 50. An excess of 1,4-butanediol over ethylene glycol is preferred. Satisfying the above range can improve the adhesiveness of the crystalline polyester resin.

The crystallinity referred to in the present invention means that, using a differential scanning calorimeter (DSC), the temperature is raised from room temperature to 250°C at 20°C/min, cooled from 250°C to -50°C at 20°C/min, and then It refers to a material that exhibits a distinct melting peak during the second heating process when the temperature is raised from -150°C to 250°C at a rate of 20°C/min. Since the polyester resin is crystalline, an effect of improving heat resistance and improving mechanical properties can be expected.

The catalyst used in producing the crystalline polyester resin of the present invention is not particularly limited, and examples thereof include compounds of Ge, Sb, Ti, Al, Mn or Mg, which may be used singly or in combination of two or more. Can be used in combination. These compounds are added to the reaction system in the form of, for example, powders, aqueous solutions, ethylene glycol solutions, ethylene glycol slurries, and the like.

The melting point of the crystalline polyester resin of the present invention must be 120° C. or higher. It is preferably 121° C. or higher, more preferably 122° C. or higher. Also, the temperature must be 140° C. or lower, preferably 133° C. or lower, and more preferably 130° C. or lower. If the melting point is too high, the adhesion may deteriorate. On the other hand, if the melting point is too low, the chemical resistance may deteriorate.

The glass transition temperature of the crystalline polyester resin of the present invention is preferably 5°C or lower, more preferably 0°C or lower. If the glass transition temperature is too high, the flexibility may be insufficient. Although the lower limit is not particularly limited, it is industrially preferably -80°C or higher, more preferably -40°C or higher.

The reduced viscosity (dl/g) of the crystalline polyester resin of the present invention is preferably from 0.90 to 1.10, more preferably from 0.95 to 1.05. By setting the reduced viscosity to 0.9 or more and 1.10 or less, it can be expected to obtain a polyester resin having excellent adhesiveness.

The specific gravity of the crystalline polyester resin of the present invention is preferably 1.26 or more, more preferably 1.27 or more. If the specific gravity is low, the chemical resistance of the polyester may be lowered, resulting in poor appearance. Although the upper limit is not particularly limited, it is preferably 1.30 or less, more preferably 1.29 or less. If the specific gravity is too high, the adhesiveness may deteriorate.

The crystalline polyester resin of the present invention is preferably a random copolymer. It is believed that the random copolymerization enables the resulting adhesive layer to exhibit transparency.

As a method for producing the crystalline polyester resin, a known method (JP-A-10-182954, etc.) can be employed. Although not particularly limited, for example, the above polyhydric carboxylic acid component and polyhydric alcohol component are subjected to an esterification reaction at 150 to 250°C. Thereafter, polyalkylene glycol is added and polycondensation is carried out at 230 to 300° C. under reduced pressure to obtain the desired crystalline polyester resin. Alternatively, after transesterification at 150 to 250° C. using a derivative such as dimethyl ester of the above polyvalent carboxylic acid and a polyhydric alcohol component, polyalkylene glycol is charged and polycondensed at 230 to 300° C. while reducing pressure. By, the desired crystalline polyester resin can be obtained. At this time, if necessary, an esterification catalyst, a polycondensation catalyst, or the like can be used. In addition, various additives, stabilizers, etc. may be added depending on the purpose of use and various properties required so as not to impair the inherent properties of other thermoplastic resins.

When producing the crystalline polyester resin of the present invention, conventionally known polymerization catalysts such as titanium compounds such as tetra-n-butyl titanate, tetraisopropyl titanate, titaniumoxyacetylcetonate, antimony trioxide, and tributoxyantimony are used. Germanium compounds such as germanium oxide and tetra-n-butoxygermanium, and acetates such as magnesium, iron, zinc, manganese, cobalt and aluminum can be used. These catalysts can be used singly or in combination of two or more.

A crystal nucleating agent may be added to the crystalline polyester resin of the present invention. Transparency can be enhanced by adding 0.01 to 5 parts by mass of a crystal nucleating agent to 100 parts by mass of the crystalline polyester resin. The crystal nucleating agent accelerates the crystallization speed of the crystalline polyester resin, completes the crystallization quickly, and has the effect of controlling the size of the spherulites by adjusting the number of crystal nuclei. Specific examples of crystal nucleating agents include inorganic fine particles such as talc, silica, graphite, carbon powder, pyroferrite, gypsum, and neutral clay, metal oxides such as magnesium oxide, aluminum oxide, and titanium dioxide, sulfates, and phosphoric acid. Salts, silicates, oxalates, stearates, benzoates, salicylates, tartrates, sulfonates, montanic acid wax salts, montanic acid wax ester salts, terephthalates, carboxylates, α-olefins and an ionic copolymer composed of α,β-unsaturated carboxylic acid. Among them, metal salts such as zinc salts, calcium salts, magnesium salts, sodium salts and lithium salts of fatty acids such as hexanoic acid, lauric acid, stearic acid and montanic acid are preferable because the crystallization speed can be easily controlled. In particular, the use of a sodium salt of fatty acid facilitates the control of the spherulite size, making it easier to obtain a transparent molding.

The hot-melt adhesive of the present invention is an adhesive containing the crystalline polyester resin. By containing a crystalline polyester resin, excellent adhesiveness, chemical resistance and transparency can be exhibited. The content of the crystalline polyester resin in the hot melt adhesive is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more. If the amount is too small, the adhesion and chemical resistance may deteriorate. Also, it is preferably 99% by mass or less, more preferably 98% by mass or less. If it is too large, the transparency may be lowered.

An adhesive layer can be prepared using the hot melt adhesive of the present invention. The adhesive layer refers to the adhesive layer after the hot-melt adhesive is applied to the substrate and cured. The thickness of the adhesive layer is preferably 2 μm or more, more preferably 5 μm or more. If the thickness is too thin, the effect as an adhesive may not be exhibited. Also, it is preferably 100 μm or less, more preferably 80 μm or less.

Substrates that can be used in the present invention include, but are not limited to, metal, plastic, wood, cloth, or paper. Examples of metal materials include various metals such as aluminum, SUS, copper, iron, and zinc, and their alloys, metal plates such as plated products, metal foils, vapor deposition layers, and the like. Plastics include plastic sheets or plastic films such as polyvinyl chloride, polyester, polyolefin, polyamide, poval or polyurethane. Examples of the cloth include cotton, silk, hemp, synthetic fibers such as polyester, and the like. Examples of papers include woodfree paper, kraft paper, roll paper, glassine paper, and the like.

When the hot-melt adhesive of the present invention requires high-temperature long-term durability, it is preferable to add an antioxidant. Although the antioxidant is not particularly limited, for example, 1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate, 1,1,3 -tri(4-hydroxy-2-methyl-5-t-butylphenyl)butane, 1,1-bis(3-t-butyl-6-methyl-4-hydroxyphenyl)butane, 3,5-bis(1 ,1-dimethylethyl)-4-hydroxy-benzenepropanoic acid, pentaerythritol tetrakis(3,5-di-t-butyl-4-hydroxyphenyl)propionate and the like. but for example 3,9-bis(p-nonylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-bis(octade siloxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, tri(monononylphenyl)phosphite, triphenoxyphosphine and isodecylphosphite. These can be used singly or in combination. The amount to be added is preferably 0.1% or more and 5% or less based on the mass of the hot melt adhesive. If it is less than 0.1%, the effect of preventing thermal deterioration may be poor. If it exceeds 5%, the hot-melt adhesive and the color tone of the adhesive layer may be adversely affected.

Furthermore, when the hot melt adhesive of the present invention requires weather resistance, it is preferable to add an ultraviolet absorber and/or a hindered amine compound. Examples include, but are not limited to, benzophenone-based, benzotriazole-based, triazole-based, nickel-based, and salicyl-based light stabilizers. Specific examples include, but are not limited to, 2,2′-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, pt-butylphenylsalicylate, 2,4-di-t- Butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di -t-amyl-phenyl)benzotriazole, 2-[2'-hydroxy-3',5'-bis(α,α-dimethylbenzylphenyl)benzotriazole, 2-(2'-hydroxy-3'-t- Butyl-5'-methylphenyl)-5-chlorobenztriazole, 2-(2'-hydroxy-3',5'-di-t-butylphenyl)-5-chlorobenzothiriazole, 2,5-bis -[5′-t-butylbenzoxazolyl-(2)]-thiophene, bis(3,5-di-t-butyl-4-hydroxybenzyl phosphate monoethyl ester) nickel salt, 2-ethoxy-5- t-Butyl-2'-ethyloxalic acid-bis-anilide 85-90% and 2-ethoxy-5-t-butyl-2'-ethyl-4'-t-butyloxalic acid-bis-anilide 10- 15% mixture, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole, 2-ethoxy-2′-ethyloxazalic acid bisanilide, 2- [2′-hydroxy-5′-methyl-3′-(3″,4″,5″,6″-tetrahydrophthalimido-methyl)phenyl]benzotriazole, bis(5-benzoyl-4-hydroxy -2-methoxyphenyl)methane, 2-(2'-hydroxy-5'-t-octylphenyl)benzotriazole, 2-hydroxy-4-i-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2 -Hydroxy-4-octadecyloxybenzophenone, light stabilizers such as phenyl salicylate. The amount to be added is preferably 0.1% or more and 5% or less based on the mass of the hot melt adhesive.

The hot melt adhesive of the present invention may optionally contain an antioxidant, an ultraviolet absorber, an inorganic filler, a stabilizer, an anti-aging agent, a coloring pigment, an inorganic or organic filler, a coupling agent, and tackiness. Enhancers, quenchers, stabilizers such as metal deactivators, flame retardants, and other additives that are widely used as additives for hot-melt adhesives can be blended within a range that does not impair the characteristics of the present invention. can.

<Example>
Examples are given below to describe the present invention in detail, but the present invention is not limited to the examples. In the present examples and comparative examples, "parts" means "mass parts".

1. Composition of Crystalline Polyester Resin A crystalline polyester resin was dissolved in chloroform-d to prepare a measurement sample. The measurement sample was analyzed using a nuclear magnetic resonance spectrometer ( ¹ H-NMR) 400-MR manufactured by VARIAN to determine the composition.

2. Measurement of Melting Point and Glass Transition Temperature Measurement was performed with a differential scanning calorimeter (DSC-200, SII). 5 mg of a sample (crystalline polyester resin) was placed in an aluminum lid-type container and sealed, heated from room temperature to 250°C at a rate of 20°C/min, cooled from 250°C to -50°C at a rate of 20°C/min, and then -150. When the temperature is raised from ° C. to 250 ° C. at a rate of 20 ° C./min, in the endothermic curve obtained in the second heating process, the position of the peak top of the heat of crystal fusion is the melting point (unit: ° C.), and an endothermic peak appears. The temperature at the intersection of the previous baseline and the tangent to the endothermic peak was taken as the glass transition temperature (Tg, unit: °C).

3. Reduced Viscosity 0.1±0.005 g of a crystalline polyester resin sample and phenoltetrachloroethane are placed in a 25 ml volumetric flask and heated to dissolve. Prepare a 25 ml solution, put the prepared sample solution into a viscosity tube, and place it in a water bath at 30°C for 15-20 minutes so that the sample solution reaches 30°C. As soon as the predetermined temperature is reached, the number of seconds in which the solvent falls is measured while checking the marked line of the viscosity tube, and the reduced viscosity (unit: dl/g) is calculated from the difference in the number of seconds in which the blank solvent falls. The calculation formula is shown in Formula 1.
Formula 1: {(seconds of sample solution falling) - (seconds of blank falling)} / (seconds of blank falling) / (weight of crystalline polyester resin x 100/25)

4. Specific Gravity A graduated cylinder containing a calcium chloride solution with a known specific gravity is placed in a water bath at 30°C for 15-20 minutes to warm to the specified temperature. After that, a small piece (5 mm×5 mm) of a crystalline polyester resin that has been completely crystallized at 60° C. is put into a graduated cylinder. The concentration of the calcium chloride solution is adjusted by adding water or a highly concentrated calcium chloride solution so that the sample floats in the liquid. The adjusted potassium chloride solution was measured by floating a hydrometer.

5. Preparation Method of Sheet Sample A 1 g sample of a crystalline polyester resin was pressed with a heat press machine at 220° C. under a pressure of 20 MPa for 1 minute. After that, it was cooled to room temperature, and a sheet sample having a thickness of 100 μm was produced.

6. Transparency The sheet sample was measured for haze and evaluated for transparency. Haze was measured using NDH5000 manufactured by Nippon Denshoku Industries Co., Ltd. to measure the haze value (%).
Evaluation criteria ○: Less than 70% haze ×: 70% or more haze

7. Adhesion The sheet sample was made into a layer structure of polyester film (Toyobo, Shine Beam (registered trademark) Q1215, thickness 250 μm) / sheet sample / polyester film (Toyobo, Shine Beam (registered trademark) Q1215, thickness 250 μm). Then, lamination was performed using a roll laminator under the conditions of 160° C.×3 MPa×1 m/min to prepare a laminated sample. Adhesion was evaluated by cutting a laminated sample into 1 cm width and measuring the T peel strength at a rate of 100 mm/min at 20° C. and 67% RH using a Tensilon tensile tester.
Evaluation criteria
◎: T-type peel strength 15 N / cm or more ○: T-type peel strength 12 N / cm or more and less than 15 N / cm △: T-type peel strength 10 N / cm or more and less than 12 N / cm ×: T-type peel strength less than 10 N / cm

8. Chemical Resistance The sheet sample and laminate sample were immersed in a tetrachlorethylene solution for 1 hour and dried at 60° C. for 20 minutes. A total of 4 cycles were carried out, with this operation as 1 cycle. The sheet samples were measured for swelling rate, and the laminate samples were visually checked for changes in appearance. The swelling rate was determined by the following formula.
Swelling rate (%) = (weight of sheet sample after immersion - weight of sheet sample before immersion) / weight of sheet sample before immersion x 100
Evaluation criteria
<Seat sample>
◎: swelling ratio less than 110% ○: swelling ratio 110% or more and less than 120% △: swelling ratio 120% or more and less than 140% ×: swelling ratio 140% or more <Lamination sample>
○: No change in appearance of laminated sample ×: Change in appearance of laminated sample

9. Flexibility The sheet sample was cut to a width of 1 cm x 12 cm, and was fixed at 25°C for 3 days while being curved as shown in Fig. 1 . After that, the fixation was released, and when the film was passed through a roll lamination, it was measured how much the deformation of the film returned to its original state.
Evaluation criteria ○: The film returns to its original state ×: The deformation of the film is fixed and does not return to its original state

Example 1 (Synthesis of crystalline polyester resin (a-1))
In a reactor equipped with a stirrer, a thermometer, and a condenser for distillation, 1035 parts of terephthalic acid, 148 parts of isophthalic acid, 260 parts of adipic acid, 657 parts of ethylene glycol, 636 parts of 1,4-butanediol, talc ( 20 parts of Hayashi Kasei Micron White (registered trademark) 5000) and 1.6 parts of tetra-n-butyl titanate were charged, the temperature was gradually raised to 240 ° C. over 3 to 5 hours, and the distilled water was added to the system. Esterification reaction was carried out while removing outside. After completion of the esterification reaction, the temperature was lowered to 170°C, and 196 parts of polytetramethylene glycol was charged. A 90 minute post-polymerization was carried out as follows. Thereafter, the pressure was returned to normal pressure with nitrogen to obtain a crystalline polyester resin. Table 1 shows the composition and characteristic values of the crystalline polyester resin (a-1) thus obtained. Each measurement evaluation item followed the method described above.

Examples 2 to 9, Comparative Examples 1 to 7 (Synthesis of crystalline polyester resins (a-2) to (a-16))
Polyester resins (a-2 to a-16) were synthesized in the same manner as the crystalline polyester (a-1). However, the types and blending ratios of raw materials were changed as shown in Table 1. Table 2 shows the evaluation results of the obtained resin.

As shown in Table 2, the hot-melt adhesives of Examples 1 to 9 of the present invention had good adhesiveness, transparency and chemical resistance. Comparative Examples 1 and 2 had poor chemical resistance due to their low melting points. In Comparative Example 3, the 1,4-butanediol content was high, so the crystallinity was high and the transparency was poor. In Comparative Example 4, the adhesion was poor due to the high melting point. In Comparative Example 5, the compounded amount of diethylene glycol was large, so the chemical resistance was poor.

The crystalline polyester resin and hot-melt adhesive of the present invention have better chemical resistance than conventional hot-melt resin adhesives. Furthermore, since it is excellent in transparency, it can be applied to fields with high design property where transparency is desired, and is useful as a hot-melt adhesive composition.

Claims (4)

A crystalline polyester resin composed of a polyvalent carboxylic acid component and a polyhydric alcohol component, containing 60 mol% or more of terephthalic acid when the polyvalent carboxylic acid component of the crystalline polyester resin is 100 mol%, and polyhydric When the alcohol component is 100 mol%, it contains 35 to 60 mol% of ethylene glycol, 35 to 60 mol% of 1,4-butanediol, 1 to 3.5 mol% of polyalkylene glycol, and 5 mol% of diethylene glycol. A crystalline polyester resin characterized by having a mol % or less and a melting point in the range of 120 to 140°C. The crystalline polyester resin according to Claim 1, which has a specific gravity of 1.26 or more. The crystalline polyester resin according to any one of claims 1 and 2, which has a glass transition temperature of 5°C or less. A hot-melt adhesive containing the crystalline polyester resin according to any one of claims 1 to 3.

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