Recycled polyester resin

Abstract

To provide a polyester resin or a polyester product which is environment friendly.SOLUTION: There is provided a recycled polyester resin having a dicarboxylic acid constituent unit and a diol constituent unit, wherein the diol constituent unit includes a constituent unit derived from diol having a cyclic acetal skeleton represented by the following formula (1), the content of the constituent unit derived from diol having a cyclic acetal skeleton is 1 to 90 mol% based on the total amount of the diol constituent unit and the recycled polyester resin has a dicarboxylic acid constituent unit derived from at least one polyester for recycling selected from the group consisting of a used polyester product and a waste polyester generated in a step of producing a polyester product and a diol constituent unit (a constituent unit derived from a polyester for recycling) in an amount of 1 mass% or more with respect to the recycled polyester resin.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a recycled polyester resin. Specifically, as a diol constituent unit, it includes a constituent unit derived from a diol having a cyclic acetal skeleton, and has a dicarboxylic acid constituent unit and a diol constituent unit derived from a polyester for recycling in an amount of 1% by mass or more. The present invention relates to a recycled polyester resin.

Background Art

[0002] As a polyester resin excellent in heat resistance, transparency, and mechanical properties and suitable for molding applications such as baby bottles, a polyester resin obtained by copolymerizing 3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane (hereinafter also referred to as "spiroglycol") and a dicarboxylic acid component is known (Patent Document 1).

[0003] When manufacturing a product using a polyester resin, generation of scraps is inevitable during the manufacturing or processing stage. In addition, polyester resin products are often discarded after use.

[0004] When incinerating scraps generated during the manufacturing / processing stage or discarded polyester products, high heat is generated, so the incinerator is easily damaged and has a short lifespan.

[0005] If not incinerated, scraps and discarded polyester products will remain semi-permanently without decomposing. In recent years, plastic containers and the like discarded as garbage have flowed into the ocean via rivers, been finely crushed by the action of waves or tides, accumulated in the bodies of marine organisms as microplastics, and concentrated through the food chain, causing adverse effects on the ecosystem of marine organisms. It is regarded as a problem that plastic is a major cause of marine pollution.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] In view of the above problems, the present invention aims to provide an environmentally considerate polyester resin and polyester products.

MEANS FOR SOLVING THE PROBLEMS

[0008] That is, the present invention includes the following aspects. [1] A recycled polyester resin having a dicarboxylic acid constituent unit and a diol constituent unit, wherein the diol constituent unit includes a constituent unit derived from a diol having a cyclic acetal skeleton represented by the following formula (1), and the content of the constituent unit derived from the diol having a cyclic acetal skeleton is 1 to 90 mol% with respect to the total amount of the diol constituent units, and having a dicarboxylic acid constituent unit and a diol constituent unit (recycled polyester-derived constituent units) derived from at least one recycled polyester selected from the group consisting of used polyester products and waste polyester generated in the process of manufacturing polyester products in an amount of 1% by mass or more based on the recycled polyester resin, Recycled polyester resin.

CHEMICAL

[10] A container using the recycled polyester resin according to any one of [1] to [6] above.

[11] A bottle made of the recycled polyester resin according to any one of [1] to [6] above.

[12] Tableware made of the recycled polyester resin according to any one of [1] to [6] above.

[13] A feeding bottle made of the recycled polyester resin according to any one of [1] to [6] above.

[14] A method for producing a recycled polyester resin using at least one recycled polyester selected from used polyester products and waste polyester generated in the process of manufacturing polyester products as a raw material, the method including a step of adding ethylene glycol and / or methanol to the recycled polyester to obtain a depolymerized product. [Advantages of the Invention]

[0009] According to the present invention, there is provided an environmentally considerate recycled polyester resin containing dicarboxylic acid structural units and diol structural units derived from at least one recycled polyester selected from the group consisting of used polyester products and waste polyester generated in the process of manufacturing polyester products, which can be used for manufacturing various molded articles and various products. [Embodiments for Carrying Out the Invention]

[0010] Hereinafter, embodiments for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. The following present embodiment is an exemplification for explaining the present invention and is not intended to limit the present invention to the following contents. The present invention can be appropriately modified and implemented within the scope of its gist.

[0011] The present invention relates to a recycled polyester resin having dicarboxylic acid structural units and diol structural units.

[0012] (Dicarboxylic Acid Structural Units) As the dicarboxylic acid structural unit, a terephthalic acid unit and / or a 2,6-naphthalenedicarboxylic acid unit is preferable, and a 2,6-naphthalenedicarboxylic acid unit is particularly preferable.

[0013] Furthermore, within a range not impairing the object of the present invention, aliphatic dicarboxylic acid units such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, cyclohexanedicarboxylic acid, decahydrophthalic acid, norbornanedicarboxylic acid, tricyclodecanedicarboxylic acid, pentacyclododecanedicarboxylic acid, 3,9-bis(1,1-dimethyl-2-carboxyethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane, 5-carboxy-5-ethyl-2-(1,1-dimethyl-2-carboxyethyl)-1,3-dioxane; aromatic dicarboxylic acid units such as isophthalic acid, phthalic acid, 2-methylterephthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, tetralindicarboxylic acid may be included.

[0014] (Diol structural unit) The recycled polyester resin of the present invention includes, as a diol structural unit, a structural unit derived from a diol having a cyclic acetal skeleton represented by the following formula (1) (hereinafter, may be abbreviated as "cyclic acetal-based diol structural unit"). [Chemical formula] In formula (1), R 1 and R 2 each independently represents an aliphatic group having 1 to 10 carbon atoms, an alicyclic group having 3 to 10 carbon atoms, or an aromatic group having 6 to 10 carbon atoms, and preferably represents a methylene group, an ethylene group, a propylene group, a butylene group or a structural isomer thereof, for example, an isopropylene group, an isobutylene group.

[0015] Particularly preferably, the cyclic acetal - based diol structural unit is 3,9 - bis(1,1 - dimethyl - 2 - hydroxyethyl)-2,4,8,10 - tetraoxaspiro[5.5]undecane (sometimes referred to as "spiroglycol").

[0016] The recycled polyester resin of the present invention may further contain an alicyclic diol structural unit as the diol structural unit. The alicyclic diol structural unit is not particularly limited, and examples thereof include diol structural units such as 1,3 - cyclohexanedimethanol, 1,4 - cyclohexanedimethanol, 1,2 - decahydronaphthalenedimethanol, 1,3 - decahydronaphthalenedimethanol, 1,4 - decahydronaphthalenedimethanol, 1,5 - decahydronaphthalenedimethanol, 1,6 - decahydronaphthalenedimethanol, 2,7 - decahydronaphthalenedimethanol, tetralindimethanol, norbornenedimethanol, tricyclodecanedimethanol, pentacyclododecanedimethanol, etc. Among them, 1,4 - cyclohexanedimethanol units, norbornenedimethanol units, tricyclodecanedimethanol units, and 2,6 - decahydronaphthalenedimethanol units are preferred, and 1,4 - cyclohexanedimethanol units are particularly preferred.

[0017] In addition, the recycled polyester resin of the present invention may contain, as a diol structural unit, a diol structural unit other than a cyclic acetal-based diol structural unit and an alicyclic diol structural unit. Examples of the other diol structural units include aliphatic diols such as ethylene glycol, trimethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, propylene glycol, and neopentyl glycol; polyether compounds such as polyethylene glycol, polypropylene glycol, and polybutylene glycol; bisphenols such as 4,4'-(1-methylethylidene)bisphenol, methylene bisphenol (bisphenol F), 4,4'-cyclohexylidene bisphenol (bisphenol Z), and 4,4'-sulfonyl bisphenol (bisphenol S); alkylene oxide adducts of the bisphenols; aromatic dihydroxy compounds such as hydroquinone, resorcinol, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxydiphenyl ether, and 4,4'-dihydroxydiphenyl benzophenone; and diol structural units such as alkylene oxide adducts of the aromatic dihydroxy compounds.

[0018] (Content) The recycled polyester resin of the present invention contains a cyclic acetal-based diol structural unit in an amount of 1 to 90 mol%, preferably 15 to 80 mol%, more preferably 20 to 70 mol%, based on the total amount of the diol structural units. When the proportion of the cyclic acetal-based diol structural unit is within the above range, the crystallinity of the recycled polyester resin decreases and the glass transition temperature increases, so that the resin tends to have high transparency and heat resistance.

[0019] When the recycled polyester resin of the present invention has an alicyclic diol structural unit, from the viewpoint of imparting impact resistance, the proportion of the alicyclic diol structural unit is preferably 1 to 90 mol%, more preferably 10 to 90 mol%, particularly preferably 15 to 90 mol%, based on the total amount of the diol structural units. In this case, the dicarboxylic acid structural unit is preferably a 2,6-naphthalenedicarboxylic acid unit.

[0020] Examples of the recycled polyester resin that is particularly excellent in impact resistance include a recycled polyester resin in which 15 to 60 mol% of the diol structural units are cyclic acetal - based diol structural units and 15 to 85 mol% are alicyclic diol structural units.

[0021] Considering transparency, heat resistance, impact resistance, mechanical strength, etc., it is preferable that the dicarboxylic acid structural unit is a terephthalic acid unit and / or 2,6 - naphthalenedicarboxylic acid, and 5 to 90 mol% of the diol structural units are 3,9 - bis(1,1 - dimethyl - 2 - hydroxyethyl)-2,4,8,10 - tetraoxaspiro[5.5]undecane units, 5 to 90 mol% are 1,4 - cyclohexanedimethanol units, and 0 to 90 mol% are ethylene glycol units. In particular, it is preferable that the dicarboxylic acid structural unit is a terephthalic acid unit and / or 2,6 - naphthalenedicarboxylic acid unit, and 15 to 60 mol% of the diol structural units are 3,9 - bis(1,1 - dimethyl - 2 - hydroxyethyl)-2,4,8,10 - tetraoxaspiro[5.5]undecane units, 15 to 85 mol% are 1,4 - cyclohexanedimethanol units, and 0 to 70 mol% are ethylene glycol units.

[0022] (Structural units derived from polyester for recycling) In the present invention, as the dicarboxylic acid structural units and diol structural units described above, dicarboxylic acid structural units and diol structural units (structural units derived from polyester for recycling) derived from polyester for recycling are included.

[0023] The polyester for recycling is at least one selected from the group consisting of a) used polyester products and b) waste polyester.

[0024] Examples of the used polyester products in a) include, for example, polyester molded articles that have once been on the market and are recovered after use. Representative examples thereof include containers such as baby bottles.

[0025] b) The waste polyester is generated in the process of manufacturing polyester products. For example, it includes polyester resin pellets that do not meet the standards, raw material polyester that becomes unnecessary during molding, polyester resin fragments cut during molding, scraps generated during molding or processing, cuttings of transition products generated during brand change, cuttings of prototypes and defective products, etc.

[0026] The recycled polyester can be either crystalline or amorphous. For example, pellets of amorphous polyester scraps without heat treatment, crystalline pellets subjected to heat treatment, mixtures of crystalline pellets and amorphous pellets, etc. can be used.

[0027] The properties of the recycled polyester are not particularly limited, and solid forms such as cut pieces, crushed materials (powders), molded bodies (pellets, etc.) can be mentioned. In addition, it may also be in a liquid form obtained by dispersing or dissolving the solid-state recycled polyester in a solvent.

[0028] In the present invention, the structural units derived from the recycled polyester are preferably those derived from (1) a material recycled polyester obtained by material recycling the recycled polyester, (2) an oligomer obtained by semi-chemical recycling, or (3) a product obtained by chemical recycling.

[0029] (1) Material recycling means reusing the recycled polyester as a raw material for a polyester resin molded body or product without decomposition, in the form of a polymer.

[0030] (2) Semi-chemical recycling means decomposing the recycled polyester into an oligomer state and reusing it as a raw material for a polyester resin molded body or product.

[0031] (3) Chemical recycling means decomposing the polyester for recycling into a monomer state and reusing it as a raw material for polyester resin moldings or products.

[0032] In the recycled polyester resin of the present invention, 1% by mass or more, preferably 1 to 10% by mass of the entire resin is a structural unit derived from the polyester for recycling.

[0033] (Other components) The recycled polyester resin of the present invention may contain monoalcohol units such as butyl alcohol, hexyl alcohol, and octyl alcohol, polyhydric alcohol units having a trivalent or higher valence such as trimethylolpropane, glycerin, 1,3,5-pentanetriol, and pentaerythritol, monocarboxylic acid units such as benzoic acid, propionic acid, and butyric acid, polyvalent carboxylic acid units such as trimellitic acid and pyromellitic acid, and oxyacid units such as glycolic acid, lactic acid, hydroxybutyric acid, 2-hydroxyisobutyric acid, and hydroxybenzoic acid, as long as the object of the present invention is not impaired.

[0034] Further, it may contain a polymerization catalyst and various additives. Examples of the additives include antioxidants, light stabilizers, ultraviolet absorbers, plasticizers, extenders, matting agents, drying regulators, antistatic agents, anti-settling agents, surfactants, flow improvers, drying oils, waxes, fillers, colorants, reinforcing agents, surface smoothers, leveling agents, curing reaction accelerators, and chain length extenders. In addition, resins and oligomers such as polyolefin resins, polyester resins, polyamide resins, polycarbonate resins, acrylonitrile resins, vinyl chloride resins, vinyl acetate resins, polyacrylic acid resins, polymethacrylic acid resins, polystyrene, ABS resins, polyimide resins, and AS resins can also be added.

[0035] (Uses and characteristics) The recycled polyester resin of the present invention can be used for various applications. For example, it can be used for injection moldings, extruded moldings such as sheets, films, and pipes, bottles, foams, adhesives, adhesives, paints, and the like.

[0036] The injection-molded article may be an insert-molded or two-color molded article. The sheet may be single-layer or multi-layer, the film may be single-layer or multi-layer, and may be unstretched, uniaxially or biaxially stretched, and may be laminated on a steel plate or the like. The film may also be produced by inflation molding.

[0037] The bottle may be a direct blow bottle, an injection blow bottle, or an injection-molded bottle.

[0038] The foam may be a bead foam or an extruded foam. It is particularly suitable for products used inside automobiles, packaging materials for import and export, food packaging materials for retort processing or microwave heating, baby bottles and tableware for heat sterilization, etc., which require high heat resistance. It is also suitable for applications that require UV barrier properties, such as packaging materials for containers, etc., and baby bottles that can be UV sterilized.

[0039] From the perspective of heat resistance, the glass transition temperature of the recycled polyester resin of the present invention is preferably 95 °C or higher, more preferably 110 °C or higher, and particularly preferably 130 °C or higher. When the glass transition temperature is within the above range, the recycled polyester resin of the present invention can be applied to applications that require high heat resistance, such as applications inside automobiles and in ship holds passing through the equator (said to reach 70-80 °C), where conventional PET or modified PET partially copolymerized with 1,4-cyclohexanedimethanol and isophthalic acid could not be used. Specifically, it can be suitably used for automotive interiors, air fresheners used inside automobiles, containers for eye drops, etc., and packaging materials used for import and export, such as blister packs. It is also suitable for applications that require high-temperature treatment, such as food packaging materials for microwave heating or retort processing, baby bottles and tableware for heat sterilization.

[0040] Also, the heat quantity of the crystallization peak during cooling of the recycled polyester resin of the present invention is preferably 5 J / g or less, and more preferably 3 J / g or less. When the crystallization peak during cooling is within the above range, the recycled polyester resin of the present invention can be suitably used for applications that require high transparency.

[0041] The haze of a test piece with a thickness of 3.2 mm obtained by injection molding the recycled polyester resin of the present invention is preferably 4% or less, more preferably 3% or less.

[0042] Furthermore, in the recycled polyester resin of the present invention, by setting the cyclic acetal diol structural unit and the alicyclic diol structural unit in the diol structural unit to a more appropriate ratio, particularly excellent impact resistance can be imparted. Specifically, when 5 to 90 mol% of the diol structural unit is a cyclic acetal diol structural unit and 5 to 90 mol% is an alicyclic diol structural unit, the impact resistance is particularly excellent. Using a sheet with a length of 2.5 cm, a width of 2.5 cm, and a thickness of 0.28 mm, the 50% fracture energy (J) determined by performing a DuPont type falling impact test in which a striker is dropped onto the sheet under the condition of a striker shape of φ1 / 4 inch is 1 J / m or more.

[0043] The recycled polyester resin of the present invention can impart UV barrier properties by setting the 2,6-naphthalenedicarboxylic acid unit in the dicarboxylic acid structural unit to an appropriate ratio. Specifically, when 0.1 to 100 mol% of the dicarboxylic acid structural unit is a 2,6-naphthalenedicarboxylic acid unit, the polyester resin composition of the present invention has good UV barrier properties.

[0044] The recycled polyester resin of the present invention may be melt-kneaded with a thermoplastic resin such as polyethylene terephthalate or polybutylene terephthalate according to the application within a range that does not inhibit the purpose.

[0045] (Production method) The method for producing the recycled polyester resin of the present invention (hereinafter referred to as the production method of the present invention) is not particularly limited as long as at least one recycled polyester selected from used polyester products and waste polyester generated in the process of producing polyester products is used as a raw material.

[0046] For example, a virgin polyester resin is produced by a melt polymerization method such as a transesterification method or a direct esterification method, or a conventionally known method such as a solution polymerization method using a monomer material not derived from a polyester for recycling, and (1) a material recycled polyester may be mixed with this virgin polyester resin.

[0047] Further, in producing a polyester resin by a known method using a monomer material or an oligomer material not derived from a polyester for recycling, (2) an oligomer component obtained by semi-chemical recycling and (3) a monomer component obtained by chemical recycling may be used together.

[0048] The production method of the present invention preferably includes a step of subjecting the polyester for recycling to material recycling, semi-chemical recycling or chemical recycling, more preferably includes a step of subjecting the polyester for recycling to semi-chemical recycling or chemical recycling, particularly preferably includes a step of adding ethylene glycol and / or methanol to the polyester for recycling to obtain a depolymerized product, and most preferably preferably includes a step of adding ethylene glycol to obtain an oligomer or adding methanol after adding ethylene glycol to obtain a monomer.

Claims

1. A recycled polyester resin having dicarboxylic acid structural units and diol structural units, wherein the diol structural units include structural units derived from a diol having a cyclic acetal skeleton represented by the following formula (1), and the content of the structural units derived from the diol having the cyclic acetal skeleton is 1 to 90 mol% based on the total amount of the diol structural units, having dicarboxylic acid structural units and diol structural units (recycled polyester-derived structural units) derived from at least one recycled polyester selected from the group consisting of used polyester products and waste polyester generated in the process of manufacturing polyester products in an amount of 1% by mass or more based on the recycled polyester resin, Recycled polyester resin. 【Chemical 1】 (In formula (1), R １ and R ２ each independently represents an aliphatic group having 1 to 10 carbon atoms, an alicyclic group having 3 to 10 carbon atoms, or an aromatic group having 6 to 10 carbon atoms.)

2. The recycled polyester resin according to claim 1, wherein the structural units derived from the diol having the cyclic acetal skeleton are 3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane units.

3. The recycled polyester resin according to claim 1 or 2, wherein the dicarboxylic acid structural units are 2,6-naphthalenedicarboxylic acid units, and the diol structural units further contain 1 to 90 mol% of alicyclic diol structural units based on the total amount of the diol structural units.

4. The recycled polyester resin according to claim 3, wherein the alicyclic diol units are 1,4-cyclohexanedimethanol units.

5. The recycled polyester resin according to any one of claims 1 to 4, having the recycled polyester-derived structural units in an amount of 1 to 10% by mass based on the recycled polyester resin.

6. The recycled polyester-derived structural units are the following (1) to (3); (1) Dicarboxylic acid structural units and diol structural units derived from a material recycled polyester obtained by material recycling of a recycled polyester, (2) Dicarboxylic acid structural units and diol structural units derived from an oligomer obtained by semi-chemical recycling of a recycled polyester, and (3) Dicarboxylic acid structural units and diol structural units obtained by chemical recycling of a recycled polyester The recycled polyester resin according to any one of claims 1 to 5, selected from the group consisting of.

7. An injection molded article using the recycled polyester resin according to any one of claims 1 to 6.

8. An extrusion molded article using the recycled polyester resin according to any one of claims 1 to 6.

9. A foam using the recycled polyester resin according to any one of claims 1 to 6.

10. A container using the recycled polyester resin according to any one of claims 1 to 6.

11. A bottle using the recycled polyester resin according to any one of claims 1 to 6.

12. Tableware using the recycled polyester resin according to any one of claims 1 to 6.

13. A baby bottle using the recycled polyester resin according to any one of claims 1 to 6.

14. A method for producing a recycled polyester resin using at least one recycled polyester selected from used polyester products and waste polyester generated in the process of manufacturing polyester products as a raw material, the method comprising a step of adding ethylene glycol and / or methanol to the recycled polyester to obtain a depolymerized product.