JPWO2011129390A1 - Method for producing polyester and modified product thereof - Google Patents

Abstract

In order to produce polyesters (oligomers) that are soluble in organic solvents and that can be chemically modified at a relatively low cost and with high production efficiency, a mixture comprising raw material polyesters, particularly polyesters obtained from waste materials, polyol components, and water as essential components Is heated to depolymerize the raw material polyester. According to another aspect, a raw material polyester, a polyol component, water and a mixture containing polybasic acid or anhydride thereof as essential components are heated to depolymerize the raw material polyester and esterify the depolymerized product (transesterification reaction or (Including polycondensation reaction of polyester). According to another aspect, the polyester produced by any of the above methods is further chemically modified by reacting a compound having one functional group that reacts with an alcohol or carboxylic acid and one or more ethylenically unsaturated groups. To do.

Description

  The present invention relates to a method for producing a polyester and a modified product thereof by using the recovered polyester as a raw material by depolymerization or further esterification.

  Polyesters typified by polyethylene terephthalate (PET) are used in various applications such as molded products, films, and fibers. Among them, PET bottles have been rapidly increasing in use in recent years due to their light weight, excellent transparency, gas barrier properties, and high strength, and the disposal method thereof has become a social problem. For this reason, various studies have been made on the recycling of PET bottles (see Patent Documents 1 and 2).

  However, in the recycling process, there is a problem that the molecular weight of PET decreases due to hydrolysis of ester bonds, and the melt viscosity and mechanical strength of PET decrease. Such a decrease in quality is a factor in inhibiting the recycling of PET bottles. Therefore, at present, recycled PET resin is mainly used only in the field of fibers and industrial materials. However, as the amount of discarded PET bottles increases, a new effective method of using recycled PET resin is sought. ing.

  Examples of a new recycling method for waste polyester include the production of alkyd resins for paints using a depolymerization reaction with glycols (see Patent Document 3), and the production of polyester resins for paints using recycled polyesters (Patent Documents 4 and 5). (See Patent Document 6), an alcohol component containing a trihydric or lower polyhydric alcohol and a tetrahydric or higher alcohol, fats and oils and / or fatty acids And a method for producing an alkyd resin by depolymerizing a polyester resin containing terephthalic acid recovered from waste as a main raw material and performing an esterification reaction in a mixture with a polybasic acid component (see Patent Document 7) However, all are intended for use in coating compositions.

Japanese Patent Laid-Open No. 10-287844 JP-A-11-114961 Japanese Patent No. 3310661 Japanese Patent No. 3443409 Japanese Patent No. 3256537 JP 2004-307779 A Japanese Patent No. 3334713

  Conventionally, in the depolymerization of polyester, a raw material polyester and a polyhydric alcohol, generally glycol, are charged into a reactor, and the temperature is raised to perform a decomposition reaction at a temperature close to the boiling point level of glycol. At this time, the water generated by the depolymerization reaction is removed as condensed water by azeotroping with an organic solvent, generally xylene, which can form an azeotrope with water (for example, the implementation of Patent Documents 4 and 5 described above). See example). However, the addition of xylene has a problem that the wastewater treatment becomes an environmental burden, and the manufacturing cost is likely to increase and the production efficiency is likely to decrease. Furthermore, when a polybasic acid is added to synthesize a resin having a carboxyl group at the terminal, the dehydration esterification reaction of the polybasic acid and the depolymer proceeds, and the resulting product has a low acid value ( There is a problem that the chemical modification becomes difficult.

The present invention has been made in view of the prior art as described above, and can depolymerize a raw material polyester in a short time, can produce a polyester (oligomer) at a relatively low cost with high production efficiency, and is environmentally friendly. The purpose is to provide.
Furthermore, the objective of this invention is providing the manufacturing method which converts the polyester obtained from a waste material into the polyester (oligomer) which can be easily melt | dissolved in an organic solvent and can be variously modified.
Another object of the present invention is to provide a method capable of producing various polyester modified products at a relatively low cost and with high production efficiency.

  In order to achieve the above object, according to a basic aspect of the present invention, a polyester comprising a raw material polyester, a polyol component, and a mixture containing water as essential components is heated to depolymerize the raw material polyester. A manufacturing method is provided. The polyol component is a polyol having a plurality of hydroxyl groups in one molecule, and preferably contains at least a trifunctional or higher functional polyol. In another preferred embodiment, the raw material polyester is polyethylene terephthalate.

  According to another aspect of the present invention, a raw material polyester, a polyol component, water, and a mixture containing polybasic acid or anhydride thereof as essential components are heated to depolymerize the raw material polyester and esterify the depolymerized product. There is provided a method for producing a polyester, which comprises performing an ester exchange reaction and a polycondensation reaction of the polyester.

  Furthermore, according to another aspect of the present invention, the polyester produced by any one of the above methods is further combined with a compound having one functional group that reacts with alcohol or carboxylic acid and one or more ethylenically unsaturated groups. There is provided a method for producing a polyester-modified product, which is chemically modified by reaction.

The method for producing the polyester of the present invention basically depolymerizes the raw material polyester by heating a mixture containing the raw material polyester, the polyol component, and water as essential components. In addition, it can be converted into a polyester (oligomer) that can be dissolved in an organic solvent and can be chemically modified.
In another aspect, water acts as a reaction medium for efficiently performing the reaction between the raw material polyester in a pulverized or pellet form and the polyol.
Polyester generally has a high melting point of 260 ° C. or higher, and when added to the reaction vessel in a larger amount than the polyol component, or when the polyol component is a solid with a high melting point, there is a problem that stirring is difficult and inefficiency, Such a problem was solved by using water as a reaction medium.
In addition, in the case of the method of treating with a polybasic acid or its anhydride simultaneously with depolymerization, the method of adding water is not expected to increase the acid value of the depolymerized product compared to the method of not adding water. was gotten. This is considered to be because depolymerization proceeded preferentially over the esterification reaction of an acid (polybasic acid or its anhydride) and an alcohol (polyol component) by adding water.
Furthermore, according to the present invention, the polyester produced by any one of the above methods is further reacted with a compound having one functional group that reacts with alcohol or carboxylic acid and one or more ethylenically unsaturated groups. By modifying, a modified polyester having photosensitivity can be produced at a relatively low cost with high production efficiency.

As described above, the basic feature of the method for producing a polyester of the present invention is that water is used when depolymerizing the raw material polyester with a polyol component.
According to the study by the present inventors, it is possible to obtain polyester oligomers that can be chemically modified in a short time by coexisting with water, and further, no organic solvent is used in the process. It is possible to provide a manufacturing method.

  The raw material polyester used in the method of the present invention may be any conventionally known polyester, but includes polyethylene terephthalate (PET), polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene phthalate, liquid crystal polymer, and the like. . Further, recycled PET and recycled PET collected from waste such as plastic bottle waste are more preferable from the viewpoint of environmental protection. The collected PET can be crushed and washed, and the recycled PET can be obtained from the market after being washed and pelletized.

As the polyol component, all of bifunctional polyols, trifunctional or higher functional polyols and the like can be used, and they can be used alone or in combination of two or more.
Examples of the bifunctional polyol include ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, 1,3-butanediol, Neopentyl glycol, spiro glycol, dioxane glycol, adamantanediol, 3-methyl-1,5-pentanediol, methyloctanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, 2-methylpropanediol 1, Bifunctional phenols such as 3,3-methylpentanediol 1,5, hexamethylene glycol, octylene glycol, 9-nonanediol, 2,4-diethyl-1,5-pentanediol, bisphenol A Ethylene oxide modified compound of bisphenol A, propylene oxide modified compound of bifunctional phenol such as bisphenol A, ethylene oxide of bisphenol A, propylene oxide copolymer modified compound, copolymer polyether polyol of ethylene oxide and propylene oxide, polycarbonate diol, Adamantanediol, polyether diol, polyester diol, polycaprolactone diol (e.g., Plaxel 205, Plaxel L205AL, Plaxel 205U, Plaxel 208, Plaxel L208AL, Plaxel 210, Plaxel 210N, Plaxel 212, Plaxel L212AL, Plaxel 220, Plaxel 220N, Plaxel 220NP1, Plaxel L220AL, Plaque 230, Plaxel 240, Plaxel 220EB, Plaxel 220EC; all manufactured by Daicel Chemical Industries, Ltd .; trade name), hydroxyl group-terminated polyalkanediene diols (eg, 1,4-polyisoprenediol, 1,4- and 1,2-polybutadiene diols and elastomers such as hydrogenated products thereof. Examples of commercially available products of the above hydroxyl group-terminated polyalkanediene diols include EPOL (registered trademark; hydrogenated polyisoprene diol, molecular weight). 1,860, average polymerization degree 26, manufactured by Idemitsu Kosan Co., Ltd.), PIP (polyisoprene diol, molecular weight 2,200, average polymerization degree 34, manufactured by Idemitsu Kosan Co., Ltd.), polytail H (hydrogenated polybutadiene diol, molecular weight) 2,200, average degree of polymerization 39, Mitsubishi Chemical Corporation Product), R-45HT (polybutanediol, molecular weight 2,270, average polymerization degree 42, manufactured by Idemitsu Kosan Co., Ltd.), and the like.

  Examples of the tri- or higher functional polyol include glycerin, trimethylolethane, trimethylolpropane, sorbitol, pentaerythritol, ditrimethylolpropane, dipentaerythritol, tripentaerythritol, adamantanetriol, polycaprolactone triol (for example, plaxel 303, plaxel 305, Plaxel 308, Plaxel 312, Plaxel L312AL, Plaxel 320ML, Plaxel L320AL; all of which are manufactured by Daicel Chemical Industries, Ltd .; trade names), and those having aromatic rings include ethylene oxides and propylene oxides of trifunctional or higher phenol compounds Sake manufactured by Shikoku Kasei Kogyo Co., Ltd. is exemplified as a modified product or a compound having a heterocyclic ring.

  A plant-derived alcohol component (plant-derived polyol) may be used as the polyol component. As the plant-derived alcohol component, a castor oil alcohol component is preferable. As a commercial item, for example, URIC H-30, URIC H-31, URIC H-52, URIC H-56, URIC H-57, URIC H-62, URIC H-73X, URIC H-92, URIC H-420 , URIC H-854, URIC Y-202, URIC Y-403, URIC Y-406, URIC Y-563, URIC AC-005, URIC AC-006, URIC PH-5001, URIC PH-5002, URIC PH-6000 , URIC F-15, URIC F-25, URIC F-29, URIC F-40, URIC SE-2010, URIC SE-3510, URIC SE-2606, URIC SE-3506, URIC SE-2003, POLYCASTOR # 10, PO YCASTOR # 30, URIC SE-2003 (all manufactured by Itoh Oil Co., Ltd.), and the like.

  The polyol component used in the present invention preferably contains a tri- or higher functional polyol, and particularly preferably trimethylolpropane.

  The amount of the polyol component used is preferably such that the hydroxyl group of the polyol component is 0.2 mol to 8.0 mol, preferably 0.33 mol to 7.0 mol, with respect to 1 mol of the ester bond of the raw material polyester. Is more preferable.

  The amount of water used is not particularly limited, but is preferably an amount that can sufficiently stir the reaction mixture. Since water is a medium for stirring and is not taken into the reaction system in depolymerization, the amount of water added is not particularly limited. The added water is recovered during or after the depolymerization reaction.

  Moreover, in the manufacturing method of polyester of this invention, in order to accelerate | stimulate depolymerization of raw material polyester, a depolymerization catalyst can be used. Examples of the depolymerization catalyst include monobutyltin hydroxide, dibutyltin oxide, monobutyltin-2-ethylhexanoate, dibutyltin dilaurate, stannous oxide, tin acetate, zinc acetate, manganese acetate, cobalt acetate, and calcium acetate. , Lead acetate, antimony trioxide, tetrabutyl titanate, tetraisopropyl titanate and the like, and can be used alone or in combination of two or more. The amount of these depolymerization catalysts used is usually 0.005 to 5 parts by mass, particularly preferably 0.05 to 5 parts by mass with respect to 100 parts by mass of the total amount of the raw material polyester (for example, regenerated PE) and the polyol component. It is in the range of 3 parts by mass.

  In another embodiment of the polyester production method of the present invention, the raw material polyester, polyol component, water, and polybasic acid or anhydride thereof are reacted together in the presence of a depolymerization catalyst as necessary. The target polyester is obtained by simultaneously performing a depolymerization reaction of the raw material polyester and an esterification reaction (including transesterification reaction and polycondensation reaction of polyester) between the polyester, polyol component and polybasic acid component. To manufacture. At this time, as described above, the presence of water in the reaction system is presumably because depolymerization proceeds preferentially over the esterification reaction, but a product having a high acid value is obtained. In this reaction, usually, the above-mentioned components are mixed, and the target polyester resin can be efficiently produced by reacting at a temperature of about 160 ° C. to about 270 ° C. for about 2 to 10 hours with stirring. The reaction time can be greatly shortened by batch reaction.

  As the polybasic acid or anhydride thereof used in the above method, a conventionally known polybasic acid or anhydride thereof can be used. Specific examples include aromatic polycarboxylic acids such as phthalic anhydride, isophthalic acid, terephthalic acid, tetrabromophthalic anhydride, methyl hymic anhydride, tetrachlorophthalic anhydride, and anhydrides thereof, hexahydrophthalic anhydride Acids, tetrahydrophthalic anhydride, 1,4-cyclohexanedicarboxylic acid, alicyclic carboxylic acids such as 1,3-cyclohexanedicarboxylic acid and their anhydrides, maleic anhydride, fumaric acid, succinic anhydride, adipic acid, sebacine Examples thereof include aliphatic polyvalent carboxylic acids such as acid and azelaic acid, and anhydrides thereof, pyromellitic anhydride, trimellitic anhydride, trifunctional or higher carboxylic acid such as methylcyclohexenedicarboxylic acid anhydride, alone or Two or more types can be used in combination.

  Furthermore, in the method for producing a modified polyester of the present invention, the polyester produced by any one of the above methods is further subjected to one functional group that reacts with alcohol or carboxylic acid and one or more ethylenically unsaturated groups (acryloyl group). Alternatively, photosensitivity is imparted by reacting a compound having a methacryloyl group) and chemically modifying it. This reaction is the same as the conventionally known esterification reaction. In the presence or absence of an organic solvent, an acid catalyst or a polymerization inhibitor is usually added and the reaction is carried out at about 80 ° C. to about 130 ° C. for 2 hours. Perform for 10 hours. The synthesis can be carried out at normal pressure or under pressure, and the reaction temperature can be lowered under pressure. In addition, there is no problem in characteristics even if an unreacted hydroxyl group derived from the depolymerized product is present in the obtained photosensitive compound (acrylate or methacrylate compound).

Examples of the functional group capable of reacting with the alcohol or carboxylic acid include a carboxyl group, an isocyanate group, a cyclic ether group, and a hydroxyl group.
Examples of the compound having one carboxyl group and one or more ethylenically unsaturated groups include acrylic acid, dimer of acrylic acid, methacrylic acid, β-styrylacrylic acid, β-furfurylacrylic acid, crotonic acid, α -Half ester compounds of cyanocinnamic acid, cinnamic acid, (meth) acrylic acid caprolactone adduct, and saturated or unsaturated dibasic acid anhydride and (meth) acrylates having one hydroxyl group in one molecule Can be mentioned. Examples of (meth) acrylates having a hydroxyl group for producing a half ester compound include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, trimethylolpropane di (meth) acrylate, Examples include pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, and phenylglycidyl (meth) acrylate. Examples of the dibasic acid anhydride for producing the half ester compound include succinic anhydride, maleic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylendomethylenetetrahydro Phthalic anhydride etc. are mentioned, It can use individually or in combination of 2 or more types.
In the present specification, (meth) acrylate is a term that collectively refers to acrylate, methacrylate, and mixtures thereof, and the same applies to other similar expressions.

  The (meth) acrylic monomer having an isocyanate group is not particularly limited as long as it is an isocyanate compound having one isocyanate group and one or more ethylenically unsaturated groups in one molecule. Specific examples include, for example, (meth) acryloyloxyethyl isocyanate, (meth) acryloyloxyethoxyethyl isocyanate, bis (acryloxymethyl) ethyl isocyanate, or modified products thereof, alone or in combination of two or more. Can be used in combination. Commercially available products include “Karenz MOI” (methacryloyloxyethyl isocyanate), “Karenz AOI” (acryloyloxyethoxyethyl isocyanate), “Karenz MOI-EG” (methacryloyloxyethoxyethyl isocyanate), “Karenz MOI BM” (Karenz MOI isocyanate block), "Karenz MOI-BP" (Karenz MOI isocyanate block), and "Karenz BEI" (1,1-bis (acryloxymethyl) ethyl isocyanate) are commercially available from Showa Denko K.K. ing. These trade names are registered trademarks. Furthermore, a half urethane compound of a compound having one hydroxyl group and one or more ethylenically unsaturated groups in one molecule and a diisocyanate such as isophorone diisocyanate, toluylene diisocyanate, tetramethylxylene diisocyanate, hexamethylene diisocyanate is also used. can do.

  Examples of the compound having one cyclic ether group and one or more ethylenically unsaturated groups in one molecule include 2-hydroxyethyl (meth) acrylate glycidyl ether, 2-hydroxypropyl (meth) acrylate glycidyl ether, 3-hydroxy Propyl (meth) acrylate glycidyl ether, 2-hydroxybutyl (meth) acrylate glycidyl ether, 4-hydroxybutyl (meth) acrylate glycidyl ether, 2-hydroxypentyl (meth) acrylate glycidyl ether, 6-hydroxyhexyl (meth) acrylate glycidyl Examples include ether or glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl acrylate, and the like, which can be used alone or in combination of two or more.

The compound having a hydroxyl group and an ethylenically unsaturated group is not particularly limited as long as it is a compound having one hydroxyl group and one or more ethylenically unsaturated groups in one molecule. Specific examples include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, trimethylolpropane di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta ( Examples thereof include hydroxyalkyl (meth) acrylates such as (meth) acrylate, and these can be used alone or in combination of two or more.
The (meth) acrylic monomer having a functional group capable of reacting with the alcohol or carboxylic acid as described above can be used alone or in combination of two or more.

  The polyester-modified product produced by the above-described method is prepared by adding one functional group that reacts with an alcohol or carboxylic acid and one or more ethylenically unsaturated groups (acryloyl group) to the depolymerized product or the polybasic acid-modified product. Alternatively, it is a photosensitive compound (acrylate or methacrylate compound) imparted with photosensitivity by reacting with a compound having a methacryloyl group) and chemically modifying it, so that it is a photocurable resin composition or a photocurable thermosetting resin composition. It is useful as a photosensitive component of a product. For example, an oxime ester photopolymerization initiator, an α-aminoacetophenone photopolymerization initiator, an acylphosphine oxide photopolymerization initiator, a benzoin compound, an acetophenone compound, an anthraquinone compound A photocurable resin composition by blending a conventionally known and commonly used photopolymerization initiator such as a thioxanthone compound, a ketal compound, a benzophenone compound, a xanthone compound, a tertiary amine compound, a photoinitiator assistant, and a sensitizer. can do.

  EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following description, “parts” and “%” are based on mass unless otherwise specified.

Example 1
A 1000 ml four-necked round bottom separable lasco fitted with a stirrer, a nitrogen introducing tube, and a cooling tube, 600 parts of recycled PET flakes having an IV value of 0.6 to 0.7, 104 parts of neopentyl glycol (melting point: 126 ° C., the same applies hereinafter), First, 44 parts of trimethylolpropane (melting point: 58 ° C., the same applies hereinafter), 1.2 parts of dibutyltin oxide, and 120 parts of tap water were charged. The atmosphere in the flask was changed to a nitrogen atmosphere, and then immersed in an oil bath heated to 180 ° C. The temperature of the oil bath was raised to 240 ° C. while gradually removing and the reaction was continued until the inside of the flask became transparent while stirring to obtain a polyester oligomer.

Example 2
Recycled PET flakes with an IV value of 0.6-0.7, 104 parts of neopentyl glycol, 0.8 parts of dibutyl oxide, 0.8 parts of water on a 1000 ml four-necked round bottom separable lasco fitted with a stirrer, nitrogen inlet tube, and cooling tube After charging 80 parts and making the inside of the flask a nitrogen atmosphere, the flask was immersed in an oil bath heated to 180 ° C., and the temperature of the oil bath was raised to 240 ° C. while gradually removing water. The reaction was continued until it became transparent to obtain a polyester oligomer.

Example 3
Recycled PET flakes with an IV value of 0.6-0.7, 134 parts of trimethylolpropane, 134 parts of dibutyltin oxide, 0.8 parts of dibutyltin oxide, 1000 ml four-necked round bottom separable lasco fitted with a stirrer, nitrogen inlet pipe, and cooling pipe After charging 80 parts of exchange water and setting the inside of the flask to a nitrogen atmosphere, the flask was immersed in an oil bath heated to 180 ° C., the temperature of the oil bath was raised to 240 ° C. while gradually removing water, and the flask was stirred. The reaction was continued until the inside became transparent to obtain a polyester oligomer.

Example 4
A 1000 ml four-necked round bottom separable lasco fitted with a stirrer, a nitrogen introducing tube, and a cooling tube is equipped with 384 parts of recycled PET flakes having an IV value of 0.6 to 0.7, 134 parts of trimethylolpropane, pentaerythritol (melting point 260 ° C.) 136. Parts, 1.0 part of dibutyltin oxide and 80 parts of industrial water were added, the inside of the flask was made into a nitrogen atmosphere, then immersed in an oil bath heated to 180 ° C., and the oil bath was placed at 240 ° C. while gradually removing water. The reaction was continued until the inside of the flask became transparent while stirring to obtain a polyester oligomer.

Example 5
Recycled PET flakes with an IV value of 0.6 to 0.7, 134 parts of trimethylol propane, 134 parts of dibutyltin oxide, 1.0 part of dibutyltin oxide on a 1000 ml four-necked round bottom separable lasco fitted with a stirrer, nitrogen inlet pipe and cooling pipe After charging 80 parts of water and setting the inside of the flask to a nitrogen atmosphere, the flask was immersed in an oil bath heated to 180 ° C., the temperature of the oil bath was raised to 240 ° C. while gradually removing water, and the flask was stirred while stirring. The reaction was continued until became transparent to obtain a polyester oligomer.

Example 6
Recycled PET flakes having an IV value of 0.6 to 0.7, 104 parts of neopentyl glycol, 42 parts of trimethylolpropane, 42 parts of trimethylolpropane, isophthalic acid on a 1000 ml four-necked round-bottom separable lasco fitted with a stirrer, nitrogen introducing tube and cooling tube 136 parts, 1.0 part of dibutyltin oxide, and 80 parts of industrial water were charged, the inside of the flask was made into a nitrogen atmosphere, then immersed in an oil bath heated to 180 ° C., and the oil bath was removed while gradually removing water. The temperature was raised to 0 ° C., and the reaction was continued while stirring until the inside of the flask became transparent to obtain a polyester oligomer.

Example 7
Ten plastic bottles containing 500 ml of tea were prepared, the label and cap were removed, and the contents were taken out. The bottle was easily rinsed with tap water and placed in an aluminum half-size pan with a capacity of 25L. Next, 57 parts of neopentyl glycol, 22 parts of trimethylolpropane, 0.6 part of dibutyltin oxide, and 120 parts of tap water were charged and heated with a hot plate so that the internal temperature of the pan became 240 ° C. ± 5 ° C. Stirring was continued while stirring until the inside of the pan became transparent to obtain a polyester oligomer.

Example 8
Ten PET bottles containing 500 ml of soft drink were prepared, the label and cap were removed, and the contents were taken out. The bottle was put in an aluminum half-size pan with a capacity of 25L without any loss. Next, 57 parts of neopentyl glycol, 22 parts of trimethylolpropane, 0.6 part of dibutyltin oxide, and 120 parts of tap water were charged and heated with a hot plate so that the internal temperature of the pan became 240 ° C. ± 5 ° C. Stirring was continued while stirring until the inside of the pan became transparent to obtain a polyester oligomer.

Example 9
225 parts of the polyester oligomer obtained in Example 3, 187 parts of acrylic acid, 1.87 parts of paratoluenesulfonic acid, paramethoxyphenol 1 in a 1000 ml four-necked round bottom separable lasco equipped with a stirrer, a nitrogen introduction pipe and a cooling pipe .50 parts was charged and stirred to dissolve uniformly, and then immersed in an oil bath heated to 118 ° C. to continue the reaction for 16.5 hours. After completion of the reaction, the acid value of the reaction solution was measured, and an acid equivalent alkaline aqueous solution was added to the flask for neutralization. Then, brine (20 wt%) was added and stirred. Thereafter, the solution was transferred to a separatory funnel, 1.4 times as much methyl isobutyl ketone as the reaction solution was added, and the aqueous phase was discarded. The oil phase was washed again with brine (5 wt%) and the aqueous phase was discarded. Thereafter, the oil phase was reprecipitated in hexane, dissolved in methyl ethyl ketone, and impurities were removed by suction filtration. After reprecipitation of the filtrate with tap water, the supernatant is discarded, the reprecipitate is further stirred and washed with tap water, and finally diluted with carbitol acetate to a solid content of 70%. Obtained.

Comparative Example 1
Recycled PET flakes with an IV value of 0.6 to 0.7, 104 parts of neopentyl glycol, 44 parts of trimethylolpropane, 44 parts of trimethylolpropane, dibutyltin oxide on a 1000 ml four-necked round bottom separable lasco fitted with a stirrer, nitrogen inlet pipe and cooling pipe 1.2 parts and 80 parts of xylene were charged and the inside of the flask was made into a nitrogen atmosphere, then immersed in an oil bath heated to 180 ° C., and the oil bath was heated to 240 ° C. while gradually removing xylene, The reaction was continued while stirring until the inside of the flask became transparent to obtain a polyester oligomer.

Comparative Example 2
Recycled PET flakes with an IV value of 0.6 to 0.7, 104 parts of neopentyl glycol, 0.8 parts of dibutyl oxide, 0.8 parts of dibutyls, xylene on a 1000 ml four-necked round bottom separable lasco fitted with a stirrer, nitrogen inlet tube, and cooling tube After 91 parts were charged and the inside of the flask was made into a nitrogen atmosphere, the flask was immersed in an oil bath heated to 180 ° C., and the temperature of the oil bath was raised to 240 ° C. while gradually removing xylene. The reaction was continued until it became transparent to obtain a polyester oligomer.

Comparative Example 3
Recycled PET flakes with an IV value of 0.6 to 0.7, 134 parts of trimethylolpropane, 134 parts of dibutyltin oxide, 0.8 parts of dibutyltin oxide, xylene on a 1000 ml four-necked round-bottom separable lasco fitted with a stirrer, nitrogen inlet pipe, and cooling pipe After 91 parts were charged and the inside of the flask was made into a nitrogen atmosphere, the flask was immersed in an oil bath heated to 180 ° C., and the temperature of the oil bath was raised to 240 ° C. while gradually removing xylene. The reaction was continued until it became transparent to obtain a polyester oligomer.

Comparative Example 4
Depolymerization was carried out in the same manner as in Example 4 except that industrial water was not used.

Comparative Example 5
Depolymerization was conducted in the same manner as in Example 5 except that industrial water was not used.

Comparative Example 6
A 1000 ml four-necked round bottom separable lasco fitted with a stirrer, nitrogen inlet tube, and cooling tube, 423 parts of recycled PET frame having an IV value of 0.6 to 0.7, 104 parts of neopentyl glycol, 42 parts of trimethylolpropane, isophthalic acid 136 parts, 1.0 part of dibutyltin oxide and 17 parts of xylene were charged, and the atmosphere in the flask was changed to a nitrogen atmosphere. Then, the flask was immersed in an oil bath heated to 180 ° C., and the oil bath was placed at 240 ° C. while gradually removing xylene. The reaction was continued until the inside of the flask became transparent while stirring to obtain a polyester oligomer.

<Depolymerization time>
Table 1 shows the time required for depolymerization in Examples 1 to 6 and Comparative Examples 1 to 6. Moreover, even if it reacts for 10 hours or more, the thing in which the residue of PET which is a raw material was confirmed is described as "x". The measurement results are shown in Table 1.
As shown in the measurement results shown in Table 1, depolymerization does not proceed within 10 hours when water is not used in the case of a large amount of solid PET flakes or polyol having a high melting point. Some PET residue was identified. On the other hand, depolymerization progressed when water was used.
In Examples 7 and 8, it was confirmed that when water is used, a polyester oligomer can be obtained even if the PET bottle is not washed and dried and there is some dirt in the PET bottle. As described above, the production method in which depolymerization is performed using water is excellent in production efficiency and leads to energy saving in that it can be input into the reaction without passing through a drying step after washing as in the prior art.

<Molecular weight>
The molecular weights of the depolymerized products of Examples 1 to 6 and Comparative Examples 1 to 6 were measured by GPC (gel permeation chromatography). Measurement conditions were as follows. Shodex GPC KF-806L × 3 manufactured by Showa Denko Co., Ltd. was used for the column, and the column temperature was 40 ° C. Standard polystyrene was used as a reference material, and tetrahydrofuran was used as an eluent at a flow rate of 1 mL / min. The measurement results are shown in Table 1.

<Acid value>
The acid values of the depolymerized products of Example 6 and Comparative Example 6 are shown in Table 1.
It was confirmed that the acid value was increased when water was used.

<Solvent solubility>
The solvent solubility of the depolymerized products of Examples 1 to 6 and Comparative Examples 1 to 6 was confirmed.
As a confirmation method, 50 parts of various solvents were added to 50 parts of the depolymerized product, stirred to prepare a 50 wt% solution of the depolymerized product, and the transparency of the solution was evaluated. The evaluation criteria are as follows.
○: Completely transparent.
Δ: Slightly cloudy.
X: There is turbidity.

Example 10
100 parts of the acrylate resin varnish obtained in Example 9 was mixed with 5 parts of a photopolymerization initiator (Irgacure 184; manufactured by BASF Japan Ltd.), and then applied to a glass plate with a thickness of 20 μm using an applicator. did. After coating, the film was dried for 20 minutes in a hot air circulation drying oven at 80 ° C., and exposed using an exposure apparatus equipped with a high-pressure mercury lamp at an exposure amount of 1 J / cm ² to obtain an evaluation coating film.

Rubbing test:
When the evaluation coating film was rubbed 50 times with a waste cloth containing acetone, it was confirmed that there was no surface dissolution and the film was sufficiently cured.

Pencil hardness test:
A pencil of B to 9H sharpened so that the tip of the pencil core was flattened against the evaluation coating film was pressed against the coating film at an angle of 45 ° C. with a load of 1 kg. As a result of scratching the coating film by about 1 cm with this load applied and measuring the hardness of the pencil on which the coating film was not peeled off, it was 6H.

Heat resistance test:
The said evaluation coating film was put into a 200 degreeC hot-air circulation type drying furnace, and was heated for 3 minutes. The sample was taken out after heating and visually observed for melting to conduct a heat resistance test. As a result, it was confirmed that the sample had heat resistance at 200 ° C. for 3 minutes.

  As described above, the method of the present invention can convert a polyester obtained from waste materials or the like into a polyester (oligomer) that can be easily dissolved in an organic solvent and can be chemically modified.

  According to the present invention, polyesters (oligomers) that can be dissolved in various organic solvents that are useful in various technical fields such as molded articles, films, fibers, resist materials, insulating resin materials, adhesives, and the like, and can be chemically modified. The imparted polyester-modified product can be produced with high production efficiency at a relatively low cost from a raw material polyester obtained from waste materials, and a method with less environmental impact can be provided because no organic solvent is used in the production process. .

Claims (4)

  A method for producing a polyester, comprising heating a mixture containing a raw material polyester, a polyol component, and water as essential components to depolymerize the raw material polyester.   The production method according to claim 1, wherein the polyol component contains at least a trifunctional or higher functional polyol.   A method for producing a polyester comprising heating a mixture containing raw material polyester, polyol component, water and polybasic acid or anhydride thereof as essential components to depolymerize the raw material polyester and esterify the depolymerized product.   The polyester produced by the production method according to any one of claims 1 to 3 is further reacted with a compound having one functional group that reacts with alcohol or carboxylic acid and one or more ethylenically unsaturated groups. A method for producing a polyester-modified product, which is chemically modified.