JP2006160787A - Biodegradable polyester resin and adhesive by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a copolyester resin having a good bonding property to a polylactic acid material, dissolvable with widely used solvents and also excellent in biodegradability. <P>SOLUTION: This biodegradable polyester resin is constituted by (A) an aromatic dicarboxylic acid component, (B) an 8-12C aliphatic dicarboxylic acid component and (C) an aliphatic glycol component, having (30-70)/(70-30) molar ratio of the components (A)/(B), and showing ≥60% biodegradation rate at 8 weeks after making it compost in accordance with the test procedures of the JIS K6953. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a copolyester resin excellent in biodegradability and an adhesive using the same.

  In recent years, with the growing awareness of environmental issues, biodegradable plastics, especially products using polylactic acid, have been developed, and biodegradable adhesives for bonding these products have also been actively developed. It is.

  For example, Patent Document 1 proposes a method using polylactic acid itself as an adhesive, but there is a problem in adhesion because polylactic acid is hard and brittle. Patent Document 2 proposes to add a plasticizer to polylactic acid and use it as an adhesive. Polylactic acid is biodegradable, but the plasticizer is not biodegradable. The product composed of the agent and the molded product of polylactic acid was not biodegradable as a whole.

  Patent Documents 3 and 4 disclose that polylactic acid is blended with other components to form a biodegradable adhesive, but this is economically disadvantageous because a blending process is necessary.

  In Patent Document 5, Patent Document 6, and Patent Document 7, there is a method of using, as an adhesive, a resin obtained by copolymerizing polylactic acid with hydroxycarboxylic acid, polyvinyl alcohol, polycaprolactone, polybutylene succinate, aliphatic polyester, or the like. Although proposed, in these methods, since the adhesive is composed of only aliphatic monomers and polylactic acid, it has been difficult to maintain sufficient adhesiveness.

  Further, in Patent Document 8, Patent Document 9, and Patent Document 10, it is proposed that a copolymer of adipic acid, terephthalic acid, and butanediol is crosslinked with an isocyanate and used as an adhesive by mixing with a natural resin. However, in the first place, since the resin does not dissolve in a general-purpose solvent, it has been difficult to use as an adhesive.

JP 2000-38118 A JP 2000-86877 A JP-A-9-131835 JP 2002-256250 A JP-A-5-339557 JP 2000-173589 A JP 2002-88334 A Japanese National Patent Publication No. 10-508640 Japanese National Patent Publication No. 10-508647 Special table 2001-500907

  An object of the present invention is to provide a polyester resin that is biodegradable and that can be used as a solvent-based adhesive that has excellent adhesion to biodegradable substrates such as polylactic acid resin substrates. It is in.

  As a result of diligent research to solve the above problems, the present inventors include a specific amount of an aliphatic dicarboxylic acid having 8 to 12 carbon atoms as an aliphatic dicarboxylic acid component, and are soluble in a general-purpose solvent. The present inventors have found that a polyester resin having a high biodegradation rate can be produced.

  That is, the gist of the present invention is primarily composed of an aromatic dicarboxylic acid component (A), an aliphatic dicarboxylic acid component having 8 to 12 carbon atoms (B), and an aliphatic glycol component (C), and (A) / B is a biodegradable polyester resin having a biodegradability ratio of 60% or more after 8 weeks after composting according to the test procedure of JIS K6953. In addition, the biodegradable polyester resin is soluble in ethyl acetate at a concentration of 25% by mass or more at a temperature of 25 ° C., and thirdly, an adhesive using the biodegradable polyester resin.

  According to the present invention, a biodegradable resin material, in particular, a biodegradable polyester resin having sufficient adhesive force and sufficient solvent solubility for a polylactic acid material is provided, and the industrial utility value as an adhesive is Extremely expensive.

  Hereinafter, the present invention will be described in detail.

  The biodegradable polyester resin of the present invention comprises an aromatic dicarboxylic acid component (A), an aliphatic dicarboxylic acid component (B), and an aliphatic glycol component (C).

  Examples of the aromatic dicarboxylic acid component (A) include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 4,4′-dicarboxyphenyl, and 5-sodium sulfoisophthalate. Aromatic dicarboxylic acids such as acids can be exemplified.

  As the aliphatic dicarboxylic acid component (B), it is necessary to use an aliphatic dicarboxylic acid having 8 to 12 carbon atoms. When an aliphatic dicarboxylic acid composed of 7 or less carbon atoms is copolymerized, it is not preferable because it becomes insoluble in a general-purpose solvent. When 13 or more carbon atoms are copolymerized, a biodegradable resin substrate, particularly a polylactic acid-based resin group, is not preferable. Since the adhesiveness to a material becomes low, it is not preferable. Examples of the aliphatic carboxylic acid having 8 to 12 carbon atoms include suberic acid, azelaic acid, sebacic acid, 1,11-undecanedioic acid, 1,12-dodecanedioic acid, 2-methyl-1,8-octanedioic acid, Examples include 3-methyl-1,7-octanedioic acid and 2-methyl-1,10-decanedioic acid, which may be linear or have a branched structure. For the reason, a straight chain is preferable. In particular, aliphatic dicarboxylic acids having 9 or 10 carbon atoms (for example, azelaic acid, sebacic acid, etc.) are preferred for reasons of adhesion and biodegradability.

  Examples of the aliphatic glycol component (C) include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2- Methyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-amino-2-ethyl-1,3-propanediol, 2-amino-2-methyl-1,3-propane Diol, 2-ethyl-2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 1,5 -Pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanedi Aliphatic glycols such as alcohol, diethylene glycol, triethylene glycol, dipropylene glycol and tripropylene glycol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol and the like Glycol, polyethylene glycol, polypropylene glycol and the like. Among them, general-purpose ethylene glycol, 1,2-propanediol, 1,4-butanediol, and neopentyl glycol are preferable. Among them, 1,4-butanediol is preferable. Is most preferred because it has the best biodegradability.

  The molar ratio (A) / (B) needs to be 30 to 70/70 to 30, preferably 40 to 65/60 to 35, and more preferably 50 to 60/50 to 40. When the molar ratio (A) / (B) is larger than 70/30, the biodegradability is deteriorated, and when the molar ratio (A) / (B) is smaller than 30/70, the adhesiveness is poor. This is not preferable.

  In the biodegradable polyester resin of the present invention, when the total of (A) and (B) is 100 mol parts, other aliphatic dicarboxylic acids and hydroxycarboxylic acids are copolymerized within a range not exceeding 10 mol parts. May be. When the content exceeds 10 parts by mole, the adhesiveness to the biodegradable resin substrate is reduced, which is not preferable.

  Other aliphatic dicarboxylic acid components include oxalic acid, malonic acid, succinic acid, adipic acid, pentadecanedioic acid, octadecanedioic acid, eicosanedioic acid, saturated aliphatic dicarboxylic acid, fumaric acid, maleic acid, itaconic acid, Unsaturated aliphatic dicarboxylic acids such as mesaconic acid and citraconic acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 2,5 Examples thereof include norbornene dicarboxylic acid and alicyclic dicarboxylic acid of tetrahydrophthalic acid.

  Examples of the hydroxycarboxylic acid include lactic acid, p-hydroxybenzoic acid, m-hydroxybenzoic acid, o-hydroxybenzoic acid, oxirane, β-propiolactone, β-butyrolactone, γ-butyrolactone, δ-valerolactone, and ε-caprolactone. , Glycolic acid, 2-hydroxybutyric acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxyisobutyric acid, 2-hydroxy-2-methylbutyric acid, 2-hydroxyvaleric acid, 3-hydroxyvaleric acid, 4-hydroxyyoshichi Herbic acid, 5-hydroxyvaleric acid, 6-hydroxycaproic acid, 10-hydroxystearic acid and the like can also be copolymerized, and among these, it is more preferable to copolymerize lactic acid, ε-caprolactone, etc., which have high biodegradability.

  Moreover, if it is a small amount, you may use a trifunctional or more than trifunctional carboxylic acid component and alcohol component as a copolymerization component.

  Examples of the tri- or higher functional carboxylic acid component include aromatics such as trimellitic acid, pyromellitic acid, benzophenone tetracarboxylic acid, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic acid anhydride, and trimesic acid. Examples thereof include carboxylic acids and aliphatic carboxylic acids such as 1,2,3,4-butanetetracarboxylic acid.

  Examples of the tri- or higher functional alcohol component include glycerin, trimethylolpropane, trimethylolethane, pentaerythritol, α-methylglucose, mannitol, and sorbitol.

  Trifunctional or higher functional components can be used in combination of two or more depending on the properties to be imparted to the resin. In this case, the proportion of the tri- or higher functional monomer is suitably about 0.2 to 5 mole parts when the total of (A) and (B) is 100 mole parts. If it is less than 0.2 mol part, the added effect does not appear, and if it contains an amount exceeding 5 mol part, the gelation may exceed the gel point at the time of polymerization.

  The biodegradable polyester resin may contain a monocarboxylic acid or a monoalcohol. Examples of monocarboxylic acids include lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, benzoic acid, p-tert-butylbenzoic acid, cyclohexane acid, 4-hydroxyphenyl stearic acid, and the like. Examples of the alcohol include octyl alcohol, decyl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, and 2-phenoxyethanol.

  The biodegradable polyester resin of the present invention can be produced by combining the above-mentioned monomers and polycondensing by a known method. For example, all the monomer components and / or low polymers thereof can be produced under an inert atmosphere. An esterification reaction is carried out at 180 to 250 ° C. for about 2.5 to 10 hours, and then a polycondensation reaction is carried out at a temperature of 220 to 280 ° C. under a reduced pressure of 130 Pa or less to obtain a polyester resin. The method etc. can be mentioned.

  In the esterification reaction and polycondensation reaction, if necessary, organic titanate compounds such as tetrabutyl titanate, alkali metals such as zinc acetate and magnesium acetate, acetates of alkaline earth metals, trioxide Polymerization is performed using an organic tin compound such as antimony, hydroxybutyltin oxide, or tin octylate. The amount of the catalyst used at that time is preferably 1.0% by mass or less based on the mass of the resin to be produced.

  Further, when a desired acid value or hydroxyl value is imparted to the polyester resin, a polybasic acid component or a polyhydric alcohol component is further added following the polycondensation reaction, and depolymerization is performed in an inert atmosphere. be able to.

  The biodegradable polyester resin of the present invention is preferably dissolved in a general-purpose solvent such as ethyl acetate, methyl ethyl ketone (2-butanone), acetone, and toluene so as to be a solution having a concentration of 25% by mass or more at a temperature of 25 ° C. It is particularly preferable to dissolve at the above-mentioned concentration in ethyl acetate, which is said to have the lowest solubility in the solvent. Here, “dissolve” means that the resin and the solvent are uniformly mixed to become transparent, and the transparent state is maintained for at least one day. If the resin does not dissolve in the solvent, the handling becomes worse when used as an adhesive, which is not preferable.

  The biodegradable polyester resin of the present invention is required to have a biodegradation rate of 60% or more after 8 weeks of composting according to the test procedure of JIS K6953. If the biodegradation rate after 8 weeks after composting is less than 60%, the biodegradability is insufficient.

  The number average molecular weight of the biodegradable polyester resin of the present invention is preferably 4,000 or more, more preferably 12,000 or more, and most preferably 15,000 or more. If the number average molecular weight is less than 4,000, sufficient adhesive strength may not be obtained for biodegradable resin materials, particularly polylactic acid materials.

  The glass transition temperature (hereinafter referred to as Tg) of the biodegradable polyester resin is not particularly limited, but is preferably 40 ° C. or less and more preferably 10 ° C. or less from the viewpoint of adhesion to polyester.

  The biodegradable polyester resin of the present invention includes a curing agent, various additives, pigments such as titanium oxide, zinc white, carbon black, dyes, polyester resins, urethane resins, olefin resins, acrylic resins, alkyd resins as necessary. Cellulose derivatives and the like can be blended.

  In the biodegradable polyester resin of the present invention, additives such as a pigment dispersant, an ultraviolet absorber, a release agent, a pigment dispersant, and a lubricant can be blended as necessary.

  The adherend to which the adhesive of the invention can be applied is not particularly limited, but it has strong adhesiveness to biodegradable resins such as polylactic acid, polycaprolactone, polybutylene succinate and polybutylene adipate. It is preferable to use polylactic acid. Further, the shape of the adherend is not particularly limited, but is particularly suitable for adhesion of a molded body such as a film, a sheet, and a flat cable.

Hereinafter, the present invention will be described specifically by way of examples.
(1) Composition of polyester resin
^It calculated | required from < ¹ > H-NMR analysis (The product made by a Varian, 300MHz).
(2) Number average molecular weight of polyester resin GPC analysis (using liquid feeding unit LC-10ADvp type manufactured by Shimadzu Corporation and UV-visible spectrophotometer SPD-6AV type, detection wavelength: 254 nm, solvent: tetrahydrofuran, polystyrene conversion ).
(3) Glass transition temperature of polyester resin 10 mg of the polyester resin was used as a sample, and measurement was performed using a DSC (Differential Scanning Calorimetry) apparatus (DSC7 model, manufactured by PerkinElmer Co., Ltd.) at a heating rate of 10 ° C./min. An intermediate value of two bending point temperatures derived from the glass transition in the obtained temperature rise curve was determined, and this was taken as the glass transition temperature (Tg).
(4) Relative viscosity 100 mg of polyester resin is dissolved in 20 ml of a mixed solvent of phenol / 1,1,2,2-tetrachloroethane = 5/5 (mass ratio), and 20 ± 0.01 ° C. using an Ubbelohde viscometer. The flow time of each of the sample solution and the solvent was measured at a temperature of 5 ° C., and the relative viscosity was calculated by (flow time of the sample solution / flow time of the solvent).
(5) Solubility At 25 ° C., 25 g of a polyester resin and 75 g of ethyl acetate were placed in a paint shaker for 120 minutes and kept at 25 ° C. for 1 day. At this time, when the solution becomes transparent by the vibration operation and the state is maintained for one day, it is determined as “◯”, and when the solution does not become transparent by the vibration operation, However, the case where the solution became turbid or non-uniform after 1 day was judged as “x”.
(6) Biodegradability According to the test procedure of JIS K6953, the biodegradation rate after 60 weeks after composting is 60% or more as biodegradable (○), and the biodegradability is less than 60%. It was determined that there was no (×).
(7) Adhesive strength Polylactic acid film (thickness 25 μm, manufactured by Unitika Co., Ltd.) was coated with a resin solution using a tabletop coating device (manufactured by Yasuda Seiki Co., Ltd., film applicator No. 542-AB type, equipped with bar coater). . By heating in an oven set at 100 ° C. for 1 minute, a resin film with a thickness of about 10 μm is formed on the substrate, and then two coated polylactic acid films are prepared, and the coated surfaces are temporarily bonded together Thereafter, the sample was pressed for 1 minute with a hot press set at 85 ° C. to prepare a sample cut to a width of 15 mm. Thereafter, the adhesive strength was measured using a precision universal material testing machine 2020 manufactured by Intesco under an atmosphere of a temperature of 20 ° C. and a humidity of 50%. 10 N / 20 mm or more was determined to be acceptable (◯), and less than 10 N / 20 mm was determined to be unacceptable (x).

Example 1
A mixture of 415 g (25 mol parts) of terephthalic acid, 498 g (30 mol parts) of isophthalic acid, 910 g (45 mol parts) of sebacic acid and 1217 g (135 mol parts) of butanediol was stirred at 240 ° C. in an autoclave. Esterification reaction was performed by heating for 3 hours. Next, 2.0 g of tetrabutyl titanate was added as a catalyst, the pressure of the system was gradually reduced to 13 Pa after 1.5 hours, and a polycondensation reaction was performed. After 4 hours, the system was pressurized with nitrogen gas, and the resin was discharged in the form of a sheet to obtain the copolymerized polyester shown in Table 2. This polyester had a number average molecular weight of 35,000, a glass transition point of −41 ° C., and solubility, biodegradability, and adhesive strength were all good. Table 1 shows the charged composition and production conditions, and Table 2 shows the results.

Examples 2-7, Comparative Examples 1-4
The monomer used and its molar ratio were changed as shown in Table 1, and the same operation as in Example 1 was performed to obtain a copolymerized polyester shown in Table 2.

  The polyesters obtained in Examples 1 to 4 all had excellent solubility, biodegradability, and adhesive strength.

  On the other hand, each comparative example had the following problems.

  In Comparative Example 1, since an aliphatic dicarboxylic acid having 7 or less carbon atoms was used, the solubility was poor.

  In Comparative Example 2, since an aliphatic dicarboxylic acid having 13 or more carbon atoms was used, the adhesiveness was inferior.

  In Comparative Example 3, since the proportion of the aliphatic dicarboxylic acid component was below the lower limit defined in the present invention, the biodegradability was poor.

In Comparative Example 4, since the ratio of the aliphatic dicarboxylic acid component exceeded the upper limit specified in the present invention, the adhesiveness was poor.

Claims (3)

It is composed of an aromatic dicarboxylic acid component (A), an aliphatic dicarboxylic acid component (B) having 8 to 12 carbon atoms, and an aliphatic glycol component (C), and the molar ratio (A) / (B) is 30 to 70. A biodegradable polyester resin having a biodegradation rate of 60% or more after 8 weeks after composting according to the test procedure of JIS K6953. The biodegradable polyester resin according to claim 1, wherein the biodegradable polyester resin is soluble in ethyl acetate at a temperature of 25 ° C at a concentration of 25% by mass or more. An adhesive using the biodegradable polyester resin according to claim 1 or 2.