JPWO2010071019A1 - Method for producing 2-hydroxyisobutyric acid polymer and depolymerization method - Google Patents

Abstract

An object of the present invention is to use resources of a 2-hydroxyisobutyric acid polymer that is excellent in heat resistance, structural stability, and resource circulation characteristics using a renewable resource as a raw material. Specifically, when producing a 2-hydroxyisobutyric acid polymer, 2-hydroxyisobutyric acid obtained by polymerization using a raw material 2-hydroxyisobutyric acid or a derivative thereof obtained from a renewable resource A process for producing a 2-hydroxyisobutyric acid polymer comprising stabilizing the polymer by treatment with an acidic substance, and solvolysis in the presence of water and / or alcohol with or without heat It consists of the depolymerization method of 2-hydroxyisobutyric acid polymer which consists of obtaining raw materials such as 2-hydroxyisobutyric acid and methacrylic acid by decomposing.

Description

The present invention relates to a method for producing a 2-hydroxyisobutyric acid polymer excellent in heat resistance, structural stability, and resource circulation characteristics using a renewable resource as a raw material. Furthermore, the present invention selectively depolymerizes 2-hydroxyisobutyric acid polymer or a resin composition containing the same into 2-hydroxyisobutyric acid and / or a derivative thereof, or methacrylic and / or methacrylic ester, which is a polymer raw material. In addition, the present invention relates to a method for recycling the obtained raw materials.

In recent years, due to the problem of global warming due to the increase in carbon dioxide gas, instead of plastic materials synthesized from fossil fuels, lactic acid polymers synthesized from biomass, which is a renewable resource, and biorecyclable and chemically recyclable Usage has been actively developed.
The advantage of using a lactic acid polymer is that the lactic acid polymer is synthesized from biomass in which carbon dioxide is fixed, so that even if incinerated, carbon dioxide does not increase significantly throughout the entire process. Supported by a neutral mindset. In addition, depolymerization-type chemical recycling, which efficiently reduces to raw materials, is a measure to return to the original raw material with very little energy, and as an environmental measure, it is a measure that goes one step further from the concept of carbon neutral.

However, lactic acid polymers have several physical problems, such as the problem that the chemical structure changes when heated at high temperatures during melt molding or thermal decomposition (racemization), and the crystallization rate is slow. Moreover, since the glass transition temperature is low, high-speed molding is difficult, and a molded product molded in an insufficiently crystallized state has a problem that it is deformed at 60 ° C. or higher. Commonly used practical lactic acid polymer is produced by ring-opening polymerization of optically active L, L-lactide and is a transparent and high-strength polymer having a melting point of about 175 ° C. The decrease in melting causes a significant decrease in melting point, and even the crystallinity disappears and its practicality is lost. Therefore, efforts are being made to improve these problems.

One of the causes of the physical problems of the lactic acid polymer as described above is known to be the presence of hydrogen on tertiary carbon which is an optically active center (Non-patent Document 1). This hydrogen atom easily repeats the desorption reaction, and racemization proceeds during the reaction.

As a polymer having a structure in which the hydrogen atom is replaced with a methyl group, a 2-hydroxyisobutyric acid polymer is known. This 2-hydroxyisobutyric acid polymer (or poly (α-hydroxyisobutyric acid)) is known to exhibit higher heat resistance (Patent Document 1) than lactic acid polymers and reduction properties to raw materials similar to lactic acid polymers. (Non-Patent Document 2). Furthermore, since this 2-hydroxyisobutyric acid polymer does not contain an optically active center in its chemical structure, it has the property that physical property degradation due to racemization can be avoided.

However, this 2-hydroxyisobutyric acid polymer also has several problems. For example, (1) Unlike polylactic acid derived from renewable resources, it is a polymer derived from fossil resources, (2) Easy degradability, which is an essential reaction characteristic of aliphatic polyester, and (3) Improvement of physical properties This is because the blending / alloying characteristics with other essential polymers are unclear, and (4) a safe and efficient monomer reduction method for resource recycling has not been found.

Regarding the point derived from the fossil resource of (1), the 2-hydroxyisobutyric acid polymer is currently synthesized by the acetone cyanohydrin method using petroleum-derived acetone (Patent Document 2). However, no examples have been synthesized from raw materials derived from renewable resources.

Regarding the suppression of the degradation of the 2-hydroxyisobutyric acid polymer in (2), it is estimated that the degradation reaction proceeds more markedly as the polymer has a lower molecular weight, so that it is estimated that the degradation starts from the molecular end. It has been found that the thermal stability is improved (Non-Patent Document 3).

Regarding blending and alloying characteristics with other polymers essential for improving the physical properties of the 2-hydroxyisobutyric acid polymer of (3), ring-opening copolymerization of 2-hydroxyisobutyric acid cyclic dimer with caprolactone and lactide, Copolymerization of 2-hydroxyisobutyric acid methyl ester with hydroxyethyl methacrylate, terephthalic acid, ethylene glycol, and adipic acid was carried out, and an increase in its moisture permeability coefficient was found. It has been found that the heat resistance and the mechanical properties due to the tensile strength tend to decrease (Patent Document 3). However, there have been no reported examples of properties improving properties by blending.

Regarding the resource circulation characteristics of the 2-hydroxyisobutyric acid polymer of (4), by thermal decomposition, 2-hydroxyisobutyric acid cyclic dimer (tetramethylglycolide (TMG)), methacrylic acid, carbon monoxide and acetone It is known to be converted (Non-Patent Document 4). However, no resource circulation technology that selectively converts and recovers any of the pyrolysis products has been disclosed.

As described above, conventionally, there is no technical disclosure regarding the synthesis of 2-hydroxyisobutyric acid polymer from renewable resources. In addition, regarding selective depolymerization to a monomer intended for resource recycling, a technique regarding clear selectivity has not been disclosed yet. As described above, lactic acid polymers produced from renewable resources have been studied for various uses, but many problems have been pointed out with respect to lactic acid polymers. Accordingly, there has been a strong demand for the development of 2-hydroxyisobutyric acid polymer and establishment of its resource recycling technology as a material with improved physical properties while maintaining the same resource recycling characteristics as lactic acid polymers.

US Pat. No. 2,811,511 Special Table 2007-522156 JP 2000-53753 A JP 2005-504506 A JP 2005-516612 Gazette JP-A-5-219969

Tsukiki, Motoyama, Shirai, Nishida, Endo, Polymer Degradation and Stability, 92, 552-559 (2007) B. J. Tighe, Applied Science Publishers, London and New York, 1984, 31-77 H. Deibig, J. Geiger, M. Sander, Die Makromolekulare Chemie, 145, 133-139 (1971) G. Sutton, B. J. Tighe, M. Roberts, Journal of Polymer Science, Polymer Chemistry Edition, 11: 1079-1093 (1973) D. G. H. Ballard, B. J. Tighe, Journal of Chemical Society (B), 1967, 702-709 (1967)

The present invention selects a method for producing a 2-hydroxyisobutyric acid polymer excellent in heat resistance, structural stability, and resource circulation characteristics from a renewable resource, and further selects a 2-hydroxyisobutyric acid polymer or a resin composition containing the same. A method for depolymerizing 2-hydroxyisobutyric acid and / or a derivative thereof, or a cyclic dimer of methacrylic acid and / or 2-hydroxyisobutyric acid, which is a raw material of the polymer, and a method for recycling its resources Is intended to provide.

In order to construct a resource recycling system for 2-hydroxyisobutyric acid polymers, the present inventors have synthesized this polymer from renewable resources, stabilized physical properties, improved various physical properties, and converted into selective raw materials. We conducted earnest research on technology. As a result, it has been found that 2-hydroxyisobutyric acid and its derivatives are synthesized from materials derived from renewable resources such as lactic acid and lactic acid derivatives. Moreover, it discovered that 2-hydroxyisobutyric acid polymer was stabilized by wash | cleaning 2-hydroxyisobutyric acid polymer obtained by superposition | polymerization of a 2-hydroxyisobutyric acid derivative using an acid and / or an acid anhydride. . Furthermore, 2-hydroxyisobutyric acid polymer can be selectively converted into 2-hydroxyisobutyric acid, a cyclic dimer of 2-hydroxyisobutyric acid, or methacrylic acid by using a specific decomposition method. I found an unexpected effect.

And when the subject of the present invention manufactures 2-hydroxyisobutyric acid polymer in which biorecycling and chemical recycling are possible, using what was obtained from renewable resources as raw material 2-hydroxyisobutyric acid or its derivative, And it is achieved by the manufacturing method of 2-hydroxyisobutyric acid polymer characterized by stabilizing the 2-hydroxyisobutyric acid polymer obtained by superposition | polymerization by an acidic substance process. Further, another object of the present invention is to solvolyze the 2-hydroxyisobutyric acid polymer in the presence of water and / or alcohol when depolymerizing the 2-hydroxyisobutyric acid polymer as described above. To obtain 2-hydroxyisobutyric acid and / or a derivative thereof, or by thermally decomposing the 2-hydroxyisobutyric acid polymer with or without using the 2-hydroxyisobutyric acid polymer, It is achieved by a depolymerization method of 2-hydroxyisobutyric acid polymer characterized in that a body is obtained.

In the present invention, the 2-hydroxyisobutyric acid derivative means an alkyl ester of α-hydroxyisobutyric acid, or a cyclic dimer thereof (tetramethylglycolide (TMG)), or an oligomer thereof. , An alkyl ester of lactic acid, or lactide, or an oligomer thereof. (Is there anything else within the scope of the present invention? Alkyl ester of α-hydroxyisobutyric acid?)

According to the present invention, (1) it is possible to synthesize a high-performance polymer with improved problems of lactic acid polymer using renewable resources as a raw material. Further, (2) the treatment using an acidic substance can remove the polymerization initiator component remaining in the 2-hydroxyisobutyric acid polymer, and as a result, a 2-hydroxyisobutyric acid polymer having excellent stability can be obtained. . Furthermore, (3) water resistance, flexibility, further heat resistance, etc. can be added by blending with many other compatible / incompatible resins, and in addition, (4) heated steam and general By using a basic substance such as a typical transesterification catalyst and magnesium oxide, it is possible to selectively convert it into a polymer raw material, which is very useful as a resource recycling method.

The present invention synthesizes 2-hydroxyisobutyric acid and then 2-hydroxyisobutyric acid polymer using renewable resources as raw materials, stabilizes 2-hydroxyisobutyric acid polymer and improves physical properties, and further uses the resource recycling method It is about. In the present invention, the renewable resource refers to organic resources produced by plants, animals, or microorganisms, and secondary resources derived from these organic resources.

Here, the organic resource means, for example, a primary fermentation product such as acetone, lactic acid, pyruvic acid, ethanol, ammonia, and the secondary resource derived therefrom is a lactic acid polymer derived from lactic acid; methyl lactate, Lactic acid esters such as ethyl lactate, butyl lactate and lactide; Pyruvate esters such as methyl pyruvate and ethyl pyruvate; and thermal decomposition products of organic resources such as methanol, carbon monoxide, carbon dioxide and hydrogen means.

In the present invention, 2-hydroxyisobutyric acid is also called α-hydroxyisobutyric acid, 2-hydroxy-2-methylpropionic acid, 2,2-dimethylglycolic acid, or 2-hydroxy-2,2-dimethylacetic acid. One of the aliphatic oxyacids having a hydroxyl group. In the present specification, these names are representatively described as 2-hydroxyisobutyric acid, and the polymer is referred to as a 2-hydroxyisobutyric acid polymer. However, in the following, the 2-hydroxyisobutyric acid polymer is sometimes referred to as poly (2-hydroxyisobutyric acid).

As a method of synthesizing 2-hydroxyisobutyric acid from a renewable resource, conventionally, a method of synthesizing from acetone cyanohydrin using an enzyme catalyst having a combination of nitrilase activity or nitrile hydratase and amidase activity (Patent Documents 4 and 5). ), Or a biochemical method using a microorganism of the genus Rhodococcus (patent document 6) is known, but the reaction rate and the treatment amount are extremely small, and it is not suitable as a conversion reaction to a polymer raw material.

By using the chemical synthesis reaction in the present invention, 2-hydroxyisobutyric acid can be produced at an industrially required reaction rate and in an amount for industrial use. Of the methods for synthesizing 2-hydroxyisobutyric acid from renewable resources, a preferred chemical synthesis reaction is as follows.

(1) Synthesis of 2-hydroxyisobutyric acid from fermentation-produced acetone (reaction formula of chemical formula 1 below).

(2) Synthesis of 2-hydroxyisobutyric acid from alkyl ester of fermented pyrpinic acid (reaction formula of the following chemical formula 2).

(3) Synthesis of 2-hydroxyisobutyric acid from fermentation-produced lactic acid ester (reaction formula of chemical formula 3 below).

The acetone cyanohydrin method represented by the above reaction formula (Chemical Formula 1) is a known production method, but its implementation with raw materials derived from renewable resources is not known. As used herein, acetone, hydrogen cyanide and ethanol are all renewable resources and derivatives thereof synthesized by acetone fermentation, a synthesis reaction from a methane / ammonia / air mixed gas (Andersov method), ethanol fermentation. For the synthesis of 2-hydroxyisobutyric acid by this reaction, the reaction conditions of the acetone cyanohydrin method using a known petroleum-derived raw material can be used as they are.

The method of synthesizing 2-hydroxyisobutyric acid from the alkyl ester of fermented pyruvic acid shown in the above reaction formula (Chemical Formula 2) is a reaction known as a Grignard reaction, and the reaction conditions carried out in the Grignard reaction Is used without any restrictions. Examples of preferable reaction conditions for the Grignard reaction using fermentation-produced pyrpinic acid are as follows. That is, esterified pyruvic acid is dissolved in a dehydrated organic solvent, for example, tetrahydrofuran, and 90-250 mol%, preferably 95-120 mol% of methylmagnesium bromide is added to this solution in the same dehydrated organic solvent with respect to pyruvate. The solution dissolved in is added dropwise at a temperature of 40 ° C. or lower, preferably 5 ° C. or lower, and then stirred at a temperature of 70 ° C. or lower, preferably 0 to 30 ° C. The progress of the reaction can be confirmed, for example, by tracking changes in the component spots derived from the raw materials and products by thin layer chromatography. After the reaction, the produced 2-hydroxybutyric acid ester can be isolated by operations such as distillation, column and extraction.

The raw material pyruvic acid used here is a substance that can be easily derived from lactic acid produced by fermentation. As a method for inducing pyruvic acid from lactic acid, a generally known oxidation reaction technique can be used without any limitation. As an example of preferable lactic acid oxidation reaction conditions, methyl lactate is dissolved in, for example, diethyl ether, and 30 mol% of sodium dihydrogen phosphate with respect to methyl lactate is added to this solution, followed by ice cooling. Furthermore, 80 mol% potassium permanganate is gradually added to methyl lactate while stirring this solution. The reaction temperature is kept at 15 ° C. and stirred for 3 hours. After a predetermined time has elapsed, the reaction solution is filtered and the filtrate is concentrated to obtain methyl pyruvate.

The synthesis reaction of 2-hydroxyisobutyric acid from lactic acid ester shown in the above reaction formula (Chemical Formula 3) is carried out using a generally known methylation reagent. As the methylation reagent used here, a conventionally known methylation reagent can be used without any limitation. More preferably, methyl halides such as methyl iodide; dimethyl carbonate; N-methylsuccinimide; More preferably, dimethyl carbonate is used as a methylation reagent.

Examples of preferable reaction conditions for the methylation of tertiary hydrogen of lactic acid ester using methyl carbonate diiodide as a methylation reagent are as follows. That is, it is at least 10.8 to 1.5 times mol, preferably 30.9 to 1.2 times mol, more preferably 100.95 to 1. mol with respect to the lactic acid ester whose hydroxyl group is protected by a protecting group such as a trimethylsilyl group. After adding 1 mole or more of a proton extracting reagent such as lithium diisopropylamide and mixing well, the methyl carbonate diiodide is at least 1 mole, preferably 1.5 to 5 moles, more preferably, lactic acid ester. 2 to 3 times mole added to form a homogeneous solution, and a metal oxide such as cesium carbonate as a catalyst is dispersed in the solution and heated and stirred in an inert atmosphere to obtain a 2-hydroxyisobutyric acid derivative. It is done. The reaction time is 5 minutes to 10 hours, preferably 10 minutes to 5 hours, more preferably 20 minutes to 1 hour. Here, the amount of the catalyst is 0.01 mol% or more, preferably 1 to 500 mol%, more preferably 10 to 300 mol% is preferably used. The reaction temperature is −120 to 50 to 250 ° C. and 30 ° C., preferably 100 to 100 to 2300 ° C., more preferably 140 to −90 to 220-10 ° C.

In addition to the above reaction, using lactide and lactic acid oligomer as raw materials, the active hydrogen on the optically active central carbon is converted to a methyl group by a methylation reaction using the above-mentioned methylation reagent, and as a 2-hydroxyisobutyric acid derivative A method of synthesizing TMG and 2-hydroxyisobutyric acid oligomer is also feasible.

In the present invention, for polymerization from 2-hydroxyisobutyric acid and its derivatives to poly (2-hydroxyisobutyric acid), a generally known polymerization method can be used without any limitation. Preferred polymerization methods include (1) dehydration polycondensation of 2-hydroxyisobutyric acid (reaction formula of the following chemical formula 4), (2) dealcoholization polycondensation of 2-hydroxyisobutyric acid esters (the chemical formula shown below) 5), (3) ring-opening polymerization of 2-hydroxyisobutyric acid cyclic dimer TMG (reaction formula of chemical formula 6 below), (4) ring-opening elimination polymerization of 2-hydroxyisobutyric anhydride sulfate (Reaction formula of the following chemical formula 7).

Among the above four kinds of polymerization methods, the reactions of Chemical Formula 6 and Chemical Formula 7 are preferred in order to synthesize higher molecular weight poly (2-hydroxyisobutyric acid).

In the polymerization reaction shown in the reaction formula of Chemical Formula 6, first, cyclic dimer TMG is synthesized by dehydrating cyclization of 2-hydroxyisobutyric acid using an acid catalyst such as p-toluenesulfonic acid, Anionic polymerization of TMG is performed to synthesize poly (2-hydroxyisobutyric acid). The anionic polymerization is carried out by bulk or solution polymerization using an organolithium compound such as alkyllithium or alkoxylithium or an organotin compound such as tin octoate as an initiator and / or catalyst. In the case of solution polymerization, aromatic solvents such as toluene and xylene; ether solvents such as THF and isobutyl ether; halogen solvents such as chloroform and dichloromethane are preferably used as the solvent. Since it can utilize in a wide temperature range, it is used more suitably.

The ring-opening elimination polymerization of 2-hydroxyisobutyric anhydride shown in the reaction formula of Chemical Formula 7 makes it easier to synthesize high molecular weight poly (2-hydroxyisobutyric acid) due to the strain energy of the ring structure. (Patent Document 1, Non-Patent Document 5).

In the present invention, the 2-hydroxyisobutyric acid polymer is a polymer having a 2-hydroxyisobutyric acid ester structure as a basic unit, and the 2-hydroxyisobutyric acid ester structure unit is 90% or more, preferably 95% or more of all units. More preferably, the polymer is 98% or more.

Components other than the 2-hydroxyisobutyric acid ester structural unit include lactones, cyclic ethers, cyclic amides, cyclic acid anhydrides, oxyacids and esters thereof copolymerizable with 2-hydroxyisobutyric acid ester; amino acids There can be copolymer component units derived from the like. Examples of the copolymer component suitably used include lactones such as L, L-lactide, D, D-lactide, meso-lactide, caprolactone, valerolactone, β-butyrolactone, and varadioxanone; ethylene oxide, propylene oxide, butylene oxide, Cyclic ethers such as styrene oxide, phenylglycidyl ether, oxetane and tetrahydrofuran; cyclic amides such as ε-caprolactam; cyclic acid anhydrides such as succinic anhydride and adipic anhydride; glycolic acid, lactic acid and 2-hydroxy There are oxyacids such as butyric acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, ω-hydroxycaproic acid and malic acid and esters thereof; amino acids such as glycine and alanine.

Furthermore, as an initiator component, as a unit that can coexist in the 2-hydroxyisobutyric acid polymer of the present invention, alcohols, glycols, glycerols, other polyhydric alcohols, carboxylic acids, and polycarboxylic acids, phenols And the like are used. Specific examples of suitably used initiator components include ethylhexyl alcohol, ethylene glycol, propylene glycol, butanediol, polyethylene glycol, polypropylene glycol, polyvinyl alcohol, glycerin, octylic acid, lactic acid, glycolic acid and the like.

In the 2-hydroxyisobutyric acid polymer produced from the renewable resource of the present invention, the above-described polymerization catalyst and initiator may remain in the form of a salt at the molecular end or as a residual component. . Such metal salts and residual metals at the molecular ends may significantly accelerate the decomposition reaction of the 2-hydroxyisobutyric acid polymer, and their removal remarkably stabilizes the practical properties of the 2-hydroxyisobutyric acid polymer. It has been found to contribute.

The metal salt or residual metal at the molecular end coexisting in the 2-hydroxyisobutyric acid polymer is obtained by converting the 2-hydroxyisobutyric acid polymer after polymerization into an organic acid, an inorganic acid, an organic acid anhydride and / or an orthoester of an organic acid, Preferably, it can be removed by washing with an organic acid, an inorganic acid, an organic acid anhydride or a mixture thereof, and as a result of the removal, the 2-hydroxyisobutyric acid polymer is significantly stabilized. Examples of the compounds suitably used as the acid and / or acid anhydride used here are as follows. That is, inorganic acids such as hydrochloric acid and sulfuric acid; aliphatic carboxylic acids such as acetic acid, formic acid, propionic acid, and adipic acid, and acid anhydrides thereof.

In the present invention, the acidic substance treatment of 2-hydroxyisobutyric acid polymer means treatment with an organic acid, inorganic acid, organic acid anhydride and / or orthoester of organic acid as described above. These acid or acid anhydride treatments can be carried out in any of the solution phase, suspension / dispersion phase, and melt phase. When carried out in the solution phase, the 2-hydroxyisobutyric acid polymer is not miscible with water, such as toluene or chloroform. It can be dissolved in an organic solvent and the metal component can be removed by a liquid-liquid washing method using a diluted inorganic acid aqueous solution of 3 equivalents or less, an organic acid or an organic acid anhydride, or an ortho ester. After the treatment, the treatment liquid is separated from the 2-hydroxyisobutyric acid polymer-containing phase by a generally known liquid-liquid separation technique. When the suspension / dispersion phase is carried out, the metal component can be removed in the same manner as in the solution phase by using an organic solvent which is capable of swelling or mixing the 2-hydroxyisobutyric acid polymer with the amorphous phase. When carried out in the molten phase, it is possible to remove the metal component by incorporating an organic acid anhydride or orthoester into the molten phase. When processing in a melt phase, the 2-hydroxyisobutyric acid polymer may be used as it is as a resin composition containing the acid anhydride or orthoester after mixing. Therefore, when processing in the melt phase, the addition amount of the organic acid anhydride or orthoester is 10 times equivalent or less, preferably 5 times equivalent or less with respect to the metal component coexisting in the 2-hydroxyisobutyric acid polymer. More preferably, it is used in an amount of 2 times or less.

When the 2-hydroxyisobutyric acid polymer in the present invention is used as a resin composition by blending and / or complexing with another polymer, if the poly (2-hydroxyisobutyric acid) component is 10% by weight or more, it will be described later. Selective chemical recycling can be carried out without any problems. However, considering practical operation efficiency, it is preferable that the poly (2-hydroxyisobutyric acid) component is 20% by weight or more.

The resin composition may be a so-called blend, alloy, composite, composite resin composition in which other general-purpose resins, reinforcing fibers, fillers, additives, etc. coexist in order to express practical physical properties. Good. As a component that can coexist, it is a necessary requirement that the physical properties of 2-hydroxyisobutyric acid polymer and chemical recycling are not hindered. Other general-purpose resins for imparting practical physical properties include, for example, polyolefins such as polyethylene and polypropylene; styrene resins such as polystyrene, ABS and AS; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polycarbonate (PC), PC / ABS, PC / AS and other polycarbonate resins; polyvinyl alcohol, polyethylene vinyl alcohol and other vinyl alcohol resins; modified polyphenylene ether, polyamide, polyoxymethylene and other engineering plastics; butadiene rubber, styrene Impact-resistant rubbers such as butadiene rubber, isoprene rubber, acrylonitrile-butadiene rubber; polylactic acid, polyhydroxybutyrate, polyhydroxyal Biodegradability improvers such as noate, polytetramethylene succinate, polytetramethylene succinate adipate, polycaprolactone, polyglycolic acid, polyparadioxanone, acetylcellulose, poly-γ-glutamic acid, polylysine and the like are preferably used. . The amount of these resins added can be appropriately selected according to the physical properties required for the product physical properties, but is generally 900 parts by weight or less, preferably 400 parts per 100 parts by weight of the 2-hydroxyisobutyric acid polymer. The amount is not more than parts by weight, more preferably not more than 100 parts by weight. These resins are usually melted during chemical recycling of the 2-hydroxyisobutyric acid polymer resin composition, and material recycling is performed by re-pelletizing.

The reinforcing fibers and fillers are not particularly limited, and known reinforcing fibers and fillers are used without any limitation. Examples of the fibers that are preferably used include, for example, glass fibers, carbon fibers, Cellulose fibers derived from plants such as kenaf and the like, and fillers that are preferably used include glass microbeads, chalk, quartz, feldspar, mica, talc, silicate, kaolin, zeolite, alumina, silica, Inorganic fillers such as magnesia, ferrite, barium sulfate, calcium carbonate; organic fillers such as epoxy resin, melamine resin, urea resin, acrylic resin, phenol resin, polyimide resin, polyamide resin, unsaturated polyester resin, perfluoro resin, etc. These fillers can be used alone or in combination of two or more. It may also be used. The addition amount of these fillers can be appropriately selected according to the physical properties required for the product, but is generally 200 parts by weight or less, preferably 100 parts by weight based on 100 parts by weight of the 2-hydroxyisobutyric acid polymer. Part or less, more preferably 50 parts by weight or less.

Other additives that can coexist in the 2-hydroxyisobutyric acid polymer resin composition include flame retardants, hydrolysis inhibitors, crystallization accelerators, lubricants, UV absorbers, antioxidants, mold release agents, and compatibilizers. Agents, antistatic agents and the like. These additives can be added within a range that does not significantly affect the practical physical properties and chemical recycling behavior of the 2-hydroxyisobutyric acid polymer, and are usually added to 100 parts by weight of the resin composition of the 2-hydroxyisobutyric acid polymer. The amount is 5 parts by weight or less, preferably 3 parts by weight or less. Examples of flame retardants include phosphorus-based flame retardants such as condensed or non-condensed phosphate esters; metal hydroxide-based flame retardant compounds such as aluminum hydroxide; boric acid-based flame retardant compounds; Inorganic flame retardant compounds such as antimony compounds, iron oxide compounds, metal nitrate compounds, titanium compounds, zirconium compounds, molybdenum compounds, aluminum compounds; nitrogen flame retardant compounds such as cyanurate compounds having a triazine ring Silica-based flame retardant compounds such as silicone oil, low melting point glass and organosiloxane; colloidal flame retardant compounds such as magnesium hydroxide, calcium hydroxide and calcium aluminate are used.

As a hydrolysis inhibitor that can coexist in the resin composition of 2-hydroxyisobutyric acid polymer, a known hydrolysis inhibitor having a function of suppressing hydrolysis of 2-hydroxyisobutyric acid polymer can be used without any limitation. . Preferred hydrolysis inhibitors include carbodiimide compounds, isocyanate compounds, and oxazoline compounds. The amount of these hydrolysis inhibitors added is 100 parts by weight of a 2-hydroxyisobutyric acid polymer resin composition. Is 5 parts by weight or less, preferably 3 parts by weight or less, and more preferably 1 part by weight or less.

The resin composition of 2-hydroxyisobutyric acid polymer is applicable to various uses. For example, by using this resin composition, molded articles such as casings of electric / electronic devices such as radios, microphones, televisions, keyboards, portable music players, mobile phones, personal computers, and various recorders can be obtained. It can also be used for applications such as automobile interior parts, various packing materials, and various decorative sheets. Examples of molding methods for these molded products include film molding, sheet molding, extrusion molding, and injection molding. Among them, injection molding is preferably used for molding electrical / electronic device product parts. More specifically, the extrusion molding can be performed according to a conventional method, for example, using a known extrusion molding machine such as a single-screw extruder, a multi-screw extruder, or a tandem extruder. The injection molding can be performed according to a conventional method using a known injection molding machine such as an in-line screw injection molding machine, a multilayer injection molding machine, or a two-head injection molding machine.

The final object of the present invention is a method for recycling resources of 2-hydroxyisobutyric acid polymer, and solvolysis of 2-hydroxyisobutyric acid polymer with water or alcohol, or heat in the presence of a catalyst. It is to be decomposed and converted into a raw material such as 2-hydroxyisobutyric acid or a derivative thereof, or methacrylic acid or an ester thereof, and by using these as raw materials, a polymer is synthesized again and reused. Therefore, another aspect of the present invention is that when depolymerizing a 2-hydroxyisobutyric acid polymer that can be biorecycled and chemically recycled, the 2-hydroxyisobutyric acid polymer is solvated in the presence of water and / or alcohol. Decompose to obtain 2-hydroxyisobutyric acid and / or derivatives thereof, or thermally decompose with or without the 2-hydroxyisobutyric acid polymer, thereby cyclic of methacrylic acid and / or 2-hydroxyisobutyric acid A method for depolymerizing 2-hydroxyisobutyric acid polymer comprising obtaining a dimer. Hereinafter, this depolymerization method will be described.

Here, for the decomposition in the presence of water or alcohol, a known solvolysis method can be used. However, when the 2-hydroxyisobutyric acid polymer is converted into 2-hydroxyisobutyric acid or an ester thereof, an aqueous solution or It is preferably carried out by contact with alcohol. On the other hand, when converting to a 2-hydroxyisobutyric acid derivative having a low molecular weight such as a 2-hydroxyisobutyric acid oligomer, a method of hydrolyzing a 2-hydroxyisobutyric acid polymer in a heated steam atmosphere is a post-treatment after reaction. This is a preferable method because of various advantages such as ease, promotion effect of hydrolysis by autocatalysis of a carboxyl group, and ease of reaction control for conversion to a predetermined molecular weight.

Hydrolysis for conversion to 2-hydroxyisobutyric acid is preferably performed by adding 15 parts by mass or more, more preferably 15 to 1,000 parts by mass of water with respect to 100 parts by mass of the solid content. The product in the case of hydrolysis is mainly hydroxyisobutyric acid and its chain oligomers. As a temperature range of hydrolysis, it is 80-250 degreeC, Preferably, 150-230 degreeC, More preferably, it is 180-210 degreeC (in the case of 100 degreeC or more, steam decomposition). The hydrolysis method is not particularly limited, but in the case of steam decomposition, it is carried out in an autoclave or a steam generator. Although it is not necessary to use a catalyst in particular, for example, as a catalyst, ammonia, aqueous ammonia, sodium hydroxide, calcium hydroxide, magnesium hydroxide and other iron oxides, iron oxides such as ferrous oxide, or Acids such as dilute hydrochloric acid, dilute sulfuric acid, and toluene sulfonic acid may be used. The amount of the catalyst added is suitably about 0.5 to 5% by weight of the whole. Although heating time is not specifically limited, 0.25-5 hours are preferable and 1-3 hours are more preferable.
Furthermore, a hydrolase may be used for the purpose of promoting dissolution by hydrolysis. The type of hydrolase is not particularly limited, and examples thereof include various microorganism-derived lipases. Conventionally known ones can be used alone or in combination of two or more.

In the case of alcoholysis, the product is mainly the ester of hydroxyisobutyric acid ester and its chain oligomers. As the type of alcohol, methanol, ethanol, isopropanol, butanol, octanol and the like can be used. The temperature in the case of alcoholysis is 100 to 250 ° C, preferably 130 to 220 ° C, and more preferably 150 to 200 ° C. The alcoholysis decomposition method is usually carried out in a pressurized reaction vessel. When a catalyst is used, the amount of catalyst added is the same as in the case of hydrolysis, and the heating time is also the same.

When converting a 2-hydroxyisobutyric acid polymer into a 2-hydroxyisobutyric acid oligomer in a heated steam atmosphere, the temperature and pressure of the heated steam treatment are performed under conditions of 100 to 155 ° C. and 0.10 to 0.56 MPa. Is preferred. In such a range, the hydrolysis rate is sufficiently large in practical use, the 2-hydroxyisobutyric acid polymer is hardly melted, and separation from other polymers becomes easy. Moreover, the temperature and pressure of a more preferable heating steam process are 100-135 degreeC, and 0.10-0.32 MPa. In such a range, in addition to the above-described effects, the pressure of water vapor can be suppressed to be relatively low, and an effect that safety problems are less likely to occur can be obtained. The hydrolysis time is appropriately selected according to the temperature and pressure in the container and the molecular weight of the target 2-hydroxyisobutyric acid polymer, but the treatment is performed in 30 minutes to 5 hours. Is appropriate. The amount of water vapor in the reaction vessel during the hydrolysis reaction is preferably 550 to 2,800 g / m ³ from the viewpoint of performing autocatalytic hydrolysis inside the 2-hydroxyisobutyric acid polymer throughout the hydrolysis process. More preferably, it is appropriate to maintain in the range of 550 to 1,700 g / m ³ .

In the present invention, an oligomer generally refers to a low molecular weight component of a polymer, but in this specification, a 2-hydroxyisobutyric acid oligomer is distinguished from poly (2-hydroxyisobutyric acid). That is, poly (2-hydroxyisobutyric acid) in the present specification means a high molecular weight product excluding 2-hydroxyisobutyric acid oligomers. On the other hand, the 2-hydroxyisobutyric acid oligomer in the present specification is qualitatively defined as a molecular weight less than the molecular weight at the critical point (critical point molecular weight) at which the amorphous phase shifts from homogeneous decomposition to heterogeneous decomposition. By exceeding such a critical point, the strength of the amorphous phase is remarkably lowered by the hydrolysis proceeding in the amorphous phase connecting the crystalline phases, and cracks are easily generated due to weak external pressure, and breakage easily occurs ( Collapse critical value). When the collapse critical value is reached, the molded body tends to collapse. The quantitative critical point molecular weight depends on crystallinity and crystal size (repeated molecular length corresponding to lamellar thickness). On the other hand, the collapse critical value is a value that varies in various ways depending on the crystal orientation, the molecular density connecting the lamella crystals, the degree of external pressure, the direction of external pressure, etc. The value of “critical point molecular weight” is larger.

The time to reach the critical point molecular weight generally depends on the initial molecular weight, crystallinity, and surface area. The higher the initial molecular weight, the longer the time to reach the critical point molecular weight, and the larger the surface area, the wider the water vapor permeation start area and the faster the reaction. On the other hand, as the degree of crystallinity increases, the proportion of amorphous material relatively decreases, so that random hydrolysis (uniform hydrolysis) that proceeds in the amorphous portion is accelerated earlier by non-random hydrolysis (non-uniform hydrolysis). Non-random hydrolysis (non-uniform hydrolysis), which is preferred for amorphous materials, promotes fracture of the amorphous part surrounding the crystalline phase and reaches the collapse critical value at an early stage. It is easy to become. One way to increase the time to reach the collapse critical value is to reduce the crystal size and reduce the crystallinity, but this leads to a decrease in the overall strength of the product, resulting in low stress. It is easy to invite collapse. Further, since the decrease in crystallinity increases the amorphous portion that is preferentially decomposed, the hydrolysis rate itself can be increased. In the present invention, the term “2-hydroxyisobutyric acid oligomer” means that the 2-hydroxyisobutyric acid ester structural unit and the terminal 2-hydroxyisobutyric acid unit are 90% or more of the total units. The same components as in the case of polymers such as

The 2-hydroxyisobutyric acid oligomer has the following characteristics. (1) Since the mechanical strength is small, it is easily crushed and pulverized. (2) Since the thermal decomposition temperature is low, it is converted into a raw material with smaller energy. (3) Since the hydrolysis rate is high, it is easily converted to 2-hydroxyisobutyric acid in the solution system. (4) Since it is a solid, there is no liquid leakage or corrosion due to acidity. (5) After crushing and crushing, it is not bulky like a molded product of poly (2-hydroxyisobutyric acid). Such a feature is extremely effective for efficiently carrying out the transportation, crushing, and storage processes that are unavoidable when chemically recycling used plastic molded products.

When the weight-average molecular weight of the 2-hydroxyisobutyric acid oligomer recovered in the present invention is less than 1,000, the melting point is remarkably lowered and it becomes easy to soften. Furthermore, the progress of hydrolysis promotes the generation of hydrophilic carboxyl groups and hydroxyl groups, and it becomes easy to swell by adsorbing and hydrating condensed water. The swollen 2-hydroxyisobutyric acid oligomer tends to cause fusion, and as a result, tends to hinder crushing and pulverization. In order to prevent such swelling and fusion, cooling is performed while reducing the pressure again after the water vapor treatment, and after the water vapor in the system is discharged, dry air and / or inert gas is introduced, which is a main factor of fusion. By efficiently removing moisture, a solid 2-hydroxyisobutyric acid oligomer that can be effectively crushed and pulverized can be obtained.

In order to significantly effectively and easily circulate the 2-hydroxyisobutyric acid polymer by chemical recycling, it is important to facilitate the crushing and pulverization of the recovered 2-hydroxyisobutyric acid oligomer. From the viewpoint that the critical point molecular weight described above, which can serve as an index for crushing or grinding the 2-hydroxyisobutyric acid oligomer, depends on the crystal size, the weight-average molecular weight of the 2-hydroxyisobutyric acid oligomer and / or its derivative is 50. Is preferably 30,000 or less, more preferably 30,000 or less, further preferably 20,000 or less, particularly preferably 15,000 or less, and 1,000 to 15,000. Most preferably it is. Further, the number average molecular position of the 2-hydroxyisobutyric acid oligomer and / or derivative thereof is preferably 25,000 or less, more preferably 15,000 or less, and still more preferably 10,000 or less. 7,500 or less is particularly preferable, and 1,000 to 7,500 is most preferable.

According to the oligomerization by hydrolysis of the present invention, a used bulky 2-hydroxyisobutyric acid polymer molded product is converted into a crushed or pulverized 2-hydroxyisobutyric acid oligomer having a large bulk density that is efficient for transportation and storage. And can be easily converted. Also, what is subject to chemical recycling is often a mixture of a 2-hydroxyisobutyric acid polymer molded product and other polymer molded products. Only the 2-hydroxyisobutyric acid polymer molded product is preferentially hydrolyzed from the mixture to form 2-hydroxyisobutyric acid oligomer, and as a result of being easily crushed and pulverized, crushed and pulverized material of 2-hydroxyisobutyric acid oligomer Can be easily separated and recovered from other polymer molded products. Therefore, this aspect is used as a pretreatment method for chemical recycling by thermal decomposition, which will be described later, for a molded product comprising a used high molecular weight 2-hydroxyisobutyric acid polymer or a resin mixture containing a 2-hydroxyisobutyric acid polymer. Can be used very effectively. That is, the present invention is a mixture of a 2-hydroxyisobutyric acid polymer molded product and another polymer molded product. -It can be converted into a pulverized product to provide a pretreatment method for chemical recycling that is effective for transportation and storage.

Another embodiment of the cyclic utilization of the 2-hydroxyisobutyric acid polymer in the present invention is a chemical recycling method by conversion to a 2-hydroxyisobutyric acid derivative or methacrylic acid and / or methacrylic acid ester by thermal decomposition.

From the 2-hydroxyisobutyric acid polymer and the 2-hydroxyisobutyric acid oligomer obtained by the hydrolysis method described above, various cyclic oligomers, linear oligomers, methacrylic acid and methacrylic acid oligomers can be produced by thermal decomposition. Among these pyrolysis products, it can be preferentially converted to TMG or methacrylic acid, which is a cyclic dimer useful in regenerating the polymer. When obtaining TMG or methacrylic acid by thermal decomposition, it is preferably heated at a temperature of 190 to 350 ° C, more preferably 200 to 300 ° C. In such a range, depolymerization can be performed in a short time. During the pyrolysis, the pressure is 0.01 MPa or less, more preferably 0.005 MPa or less, more preferably 0.001 MPa or less, and most preferably 0.0001 to 0.001 MPa. It is advantageous to obtain a high acid recovery.

When only a 2-hydroxyisobutyric acid polymer and a 2-hydroxyisobutyric acid oligomer are heated and a sufficient reaction rate cannot be obtained during thermal decomposition, the 2-hydroxyisobutyric acid polymer and 2-hydroxyisobutyric acid are used. It is preferable to obtain 2-hydroxyisobutyric acid and / or a derivative thereof or a methacrylic acid and methacrylic acid oligomer by catalytically decomposing the oligomer under reduced pressure using a catalyst. Further, TMG or methacrylic acid can be more selectively converted and recovered by thermal decomposition using an appropriate catalyst. The pyrolysis temperature is preferably 200 ° C. or higher.

The catalyst for selective conversion to TMG is not particularly limited as long as it is a homogeneous transesterification catalyst, and examples thereof include tin octylate. Moreover, the catalyst for selectively converting to methacrylic acid can be used without particular limitation as long as it is a metal oxide catalyst. Preferable methacrylic acid selection catalysts include, for example, alkaline earth oxides such as magnesium oxide and calcium oxide; long-period III-XV metal oxides such as tin oxide, and more preferably alkaline earth metals Oxides and oxides of Sn, Ti, Zr and Zn, more preferably alkaline earth metal oxides and SnO. The alkaline earth metal compound used in the present invention need not be special. Commonly known alkaline earth metal compounds include calcium compounds, magnesium compounds, barium compounds and the like, and oxides, hydroxides, carbonates, salts with organic acids, and the like are preferably used. Preferably, a calcium compound and a magnesium compound are preferably used because of their availability. More preferably, magnesium oxide is suitably used from the viewpoint of the thermal decomposition reaction selectivity. As the oxide of magnesium which is the catalyst most suitably used in the present invention, any magnesium oxide generally produced from seawater or ore can be used without any particular limitation. Examples of magnesium oxide that can be suitably used include light-burned magnesia, heavy-burned magnesia, and electrofused magnesia.

In the present invention, the alkaline earth metal compound and / or metal oxide is 0.1 to 10 parts by weight per 100 parts by weight of 2-hydroxyisobutyric acid polymer component in the resin composition of 2-hydroxyisobutyric acid polymer, Preferably 0.2 to 5 parts by weight are added. As an example of catalytic pyrolysis in the present invention, selective conversion to TMG using a tin octylate catalyst will be described. 0.01 to 5 parts by weight of tin octylate is added to 100 parts by weight of 2-hydroxyisobutyric acid polymer. And a TMG fraction can be obtained by pyrolyzing the polymer at 200 to 300 ° C. for 1 to 10 hours. In addition, TMG which is pyrolyzed and distilled as a vapor can be passed through a distillation column and fractionated to recover purified TMG. Although the purity of the TMG solution from the pyrolysis distillation step is high, TMG having higher purity can be obtained by further purification by a crystallization method or a recrystallization method using an organic solvent.

In the present invention, as a method for recovering high-purity TMG or methacrylic acid, a 2-hydroxyisobutyric acid polymer resin composition is charged into, for example, a thermal decomposition reactor set to a temperature range of 200 to 300 ° C. Although it is desirable, a method of raising the temperature from a lower temperature can also be selected. As the pyrolysis reactor suitably used, either batch type or continuous type can be implemented. Suitable reactors include an extruder, an autoclave, a fluidized bed reactor, and the like. In the case of using an extruder, the control of the thermal decomposition temperature, the thermal decomposition rate, and the heating rate can be controlled according to the temperature setting of each block of the cylinder, the number of rotations of the screw, the shape of the screw, the type of uniaxial / biaxial screw, etc. It is possible to set the temperature range at.

When the thermal decomposition of the resin composition of 2-hydroxyisobutyric acid polymer is carried out using these thermal decomposition reactors, the produced TMG or methacrylic acid is volatilized in the gas phase, so that the gas phase components are taken out. Process is essential. Each of the reactors described above has a discharge port for taking out the gas phase component and / or an inlet of an inert gas such as nitrogen gas for extruding and replacing the gas phase component. For example, in the case of an extruder having a vent structure, the vent port is preferably used as the discharge port. When taking out the gas phase component from the vent port, generally, a method of taking it out under reduced pressure is preferably carried out. The degree of vacuum and / or the exhaust speed can be set according to the amount and temperature of the vaporized component, but is usually 0.01 MPa or less, more preferably 0.005 MPa or less, and even more preferably 0.001 MPa or less. Is preferably implemented. TMG or methacrylic acid can be highly selectively recovered from the 2-hydroxyisobutyric acid polymer resin composition by the above-described methods and means.

EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.

[Example 1] Synthesis of methyl 2-hydroxyisobutyrate from methyl pyruvate (see the reaction formula of the following chemical formula 8).

A 100 mL three-necked flask equipped with a condenser and a dropping funnel was charged with 2.00 g (19.60 mmol) of methyl pyruvate and 20 mL of dehydrated tetrahydrofuran (THF). Under ice cooling, a mixed solution of 18.15 mL (1.08 mol / L; THF solution, 19.60 mmol) of methylmagnesium bromide and 15 mL of dehydrated THF was added dropwise from a dropping funnel in a nitrogen atmosphere. After completion of the dropping, the reaction was performed at room temperature for 1 hour. The progress of the reaction was followed by thin layer chromatography (TLC, developing solvent; methylene chloride). After completion of the reaction, the mixture was allowed to cool to room temperature, and 10% ammonium chloride aqueous solution was gradually added thereto to stop the reaction. The reaction solution was extracted with methylene chloride and washed with water, and then the organic layer was separated. The organic layer was dehydrated with anhydrous sodium sulfate, the solution was collected by filtration, and the solvent was distilled off under reduced pressure. The residue was subjected to preparative TLC to isolate the product: methyl 2-hydroxyisobutyrate. Yield 1.15 g (50% yield). IR and GCMS values were as follows:

IR (cm-1): 3461 (νOH), 2983, 2952-1737 (νC = O), 1465, 1430, 1374, 1275, 1193, 1145, 986, 883, 814, 767, 616; GCMS (EI): m / Z
103 (M-15)

[Example 2] Synthesis of 2-hydroxyisobutyric acid from ethyl lactate (see the reaction formula of the following chemical formula 9).

Ethyl lactate (0.4 g, 0.003 mol) and dimethyl carbonate (5.5 g, 0.061 mol) were added to the ampoule tube, and cesium carbonate (2.2 g, 0.006 mol) was added as a catalyst. The ampule tube was sufficiently cooled with liquid nitrogen and frozen, and then the pressure was reduced with a vacuum pump, and then the contents were melted on a water bath in a nitrogen atmosphere to perform nitrogen replacement. The tube was sealed again using a gas burner while cooling to liquid nitrogen temperature and reducing the pressure with a vacuum pump. The sealed tube was reacted on a drive lock bath set at 150 ° C. for 7 hours. After completion of the reaction for 7 hours while shaking the ampule tube every hour, the taken ampule tube was immersed in water and allowed to stand overnight. Thereafter, the reaction solution was decanted, and white transparent and needle-like crystals deposited on the inner surface of the ampoule tube were collected. The yield was 10 mg or less. The structure of the produced crystal was confirmed using ¹ H-NMR. The results were as follows.

¹ H-NMR
(CDCl3, TMS standard, ppm): 1.55 (s, CH3)

[Reference Example 1] Synthesis of tetramethyl glycolide (TMG) from 2-hydroxyisobutyric acid and synthesis of poly (2-hydroxyisobutyric acid) by ring-opening polymerization of TMG (see the reaction formula of the following chemical formula 10).

2-hydroxyisobutyric acid (40.0 g, 0.38 mol) was placed in a 200 ml round bottom flask, and toluene (100 ml) was added and stirred. Dean-Stark
It refluxed using Trap, 0.05 equivalent of p-toluenesulfonic acid (p-TSA) (3.7g, 0.02mol)) was added, and it was made to react for 48 hours. After confirming that the starting material and about equimolar amount (7.2 ml, 0.40 mol) of water had accumulated in the moisture receiver trap, the reaction solution was returned to room temperature, and toluene was removed as much as possible under reduced pressure. . This was diluted with diethyl ether and washed twice with water. Further, the organic layer was washed with saturated brine, dried over MgSO4, and concentrated under reduced pressure to obtain 24.4 g of white crystals. Further, purification was performed by a recrystallization method. 20 ml of ethyl acetate was added to the obtained crude crystals, and all were dissolved while heating at 50-60 ° C. While this was gradually cooled, n-hexane was added little by little, and the mixture was allowed to stand overnight in a draft to obtain colorless and transparent crystals. This operation was further repeated twice to obtain 20.1 g (0.12 mol) of transparent crystalline TMG. The synthesis yield was 73%. Values such as IR and NMR were as follows.

FT-IR (single reflection): (cm-1) 2985 (CH, CH3), 1740 (C = O, carboxylic group), 1H-NMR
(CDCl3) (ppm): 1.73 (12H, s, CH3), EI-MS: m / z = 173 (M + 1) +, DSC: Tm83.1 ° C

Next, an operation of putting the synthesized TMG (8.0 g, 0.046 mol) into a 100 ml ampoule tube and melting it under reduced pressure by a vacuum pump and pressurized dry nitrogen through a calcium chloride tube while cooling with liquid nitrogen. It performed 3 times and freeze deaeration drying was performed. This was returned to room temperature, Li-t-Bu as a polymerization initiator was added with 1.7 M pentane solution (30 μl, 0.05 mmol) in 10 ⁻³ equivalent, and the pressure was reduced by a vacuum pump while cooling with liquid nitrogen again. It was. The tube was sealed with a gas burner while reducing the pressure, and reacted for 8 hours in an oil bath at 130 ° C. to obtain a white solid. After completion of the reaction, the tube was opened, and the produced white solid was dissolved in chloroform, added dropwise to a large excess of methanol, and allowed to stand overnight at -35 ° C. The white precipitate was washed with acetone while separating by suction filtration to obtain a white powder. This was dried under reduced pressure at 110 ° C. for 2 hours using a vacuum oven. The yield of the obtained poly (2-hydroxyisobutyric acid) was 7.1 g, and the polymerization yield was 88.8%. The obtained poly (2-hydroxyisobutyric acid) was confirmed by ¹ H-NMR for structure confirmation, GPC for molecular weight, and DSC for glass transition temperature and melting point. The results were as follows.

¹ H-NMR (CDCl3)
(ppm): 1.54 (s, CH3)
GPC (polystyrene conversion): Mn 22000, MW 32000
DSC: Tg = 70.8 ℃, Tm = 190.7 ℃

Example 3 and Comparative Example 1 Thermal stabilization of poly (2-hydroxyisobutyric acid) by treatment with dilute hydrochloric acid.
0.2087 g of poly (2-hydroxyisobutyric acid) (Mn8100, Mw12000) was taken in a 100 mL Erlenmeyer flask, and 20 mL of chloroform was added to this and stirred to dissolve. This solution was transferred to a separatory funnel and washed three times with 10 mL of 1N aqueous HCl. Thereafter, the chloroform solution was separated, and chloroform was distilled off from the solution under reduced pressure using a rotary evaporator. After distillation, the film-like polymer remaining at the bottom of the flask was taken out and dried under vacuum at 40 ° C. for 4 hours. The dried film-like sample was heated to 400 ° C. under a nitrogen gas stream (100 mL / min) using a TG / DTA at a temperature rising rate of 9 ° C./min. As a result, the weight loss due to thermal decomposition started at about 250 ° C and almost completely disappeared at 310 ° C. For comparison, untreated poly (2-hydroxyisobutyric acid) was used and heated with TG / DTA under similar conditions. As a result, the weight loss due to thermal decomposition started at about 235 ° C and almost completely disappeared at 295 ° C. Comparing the above results, it was confirmed that by washing poly (2-hydroxyisobutyric acid) with a 1N HCl aqueous solution, the thermal decomposition temperature of about 15 ° C. was increased and thermal stabilization was achieved.

[Examples 4 to 6 and Comparative Example 2] Preparation of blend film of poly (2-hydroxyisobutyric acid).
Poly (2-hydroxyisobutyric acid) (Mn8100, Mw12000), polycarbonate (PC, Mn11000, Mw34000), polybutyl succinate (PBS, Mn25600, Mw72000), and polycaprolactone (PCL, Mw120,000) in the amounts shown in Table 1. It took in the sample tube bottle of a 20 mL capacity | capacitance, chloroform 4mL was added in it, and it stirred and dissolved at room temperature overnight. The solution in which both polymers were dissolved was colorless and transparent. The solution was transferred to a flat petri dish having an inner diameter of 5 cm, and the solvent chloroform was gradually evaporated on a horizontal table to form a cast film. The obtained film was unemployed transparent or white, but was an isolatable film. The isolated film was dried under vacuum at 70 ° C. for 5 hours. The film was taken out from the inside of the vacuum dryer, and the thermal property was measured using a differential scanning calorimeter (DSC) under a nitrogen stream (50 mL / min) at a heating rate of 9 ° C./min. As a result, endothermic peaks based on crystal melting of other resins blended with poly (2-hydroxyisobutyric acid) were observed at the temperatures shown in Table 1, respectively. For comparison, a cast test (Comparative Example 2) was carried out in the same manner only for poly (2-hydroxyisobutyric acid) having the same molecular weight as in Examples 4 to 6 without blending other resins. However, in the case of Comparative Example 2, unlike Examples 4 to 6, an isolatable film was not formed. From the above results, it is clear that the coexistence of other resins worked effectively on the film formation of poly (2-hydroxyisobutyric acid).

[Examples 7 to 9 and Comparative Example 3] Thermal decomposition of poly (2-hydroxyisobutyric acid) (see the reaction formula of Chemical Formula 11 below).

Poly (2-hydroxyisobutyric acid) and the thermal decomposition catalyst were weighed into a sample bottle at the ratio shown in Table 2, dissolved in chloroform (5 ml), and stirred for 3 hours. This solution was transferred to a flat petri dish and allowed to stand overnight on a horizontal platform to prepare a cast film. The obtained film was decompressed (17 Pa) with a vacuum pump while being heated to 70 ° C. in a vacuum oven, and chloroform was completely removed.

For thermal decomposition of poly (2-hydroxyisobutyric acid), about 10 mg of the sample shown in Table 2 was taken in an ampoule tube and dried under reduced pressure with a vacuum pump for 3 hours. Subsequently, the tube was cooled with liquid nitrogen, sealed with a vacuum pump, and placed in a glass tube. The glass tube oven was set to the predetermined temperature shown in Table 2 and heated for 30 minutes. The decomposition product was generated and stayed in the ampoule. After the heat treatment, the ampoule tube was cooled and crushed, and the internal pyrolysis product was dissolved in chloroform. The structure was confirmed by 1H-NMR analysis. The molar composition ratio of the product was calculated from the integral ratio of ¹ H-NMR spectrum. The results are shown in Table 2.

From the results in Table 2, when no catalyst was used (Comparative Example 3), the main product was methacrylic acid (3), but a large amount of acetone (2) was produced, and the ratio of TMG (1) was It was slight. When the octylate tin (Sn (Oct) ₂ ), which is a transesterification catalyst, was used as the thermal decomposition catalyst, it was found that the amount of TMG produced was remarkably increased and TMG selective thermal decomposition occurred. When tin oxide (SnO) and magnesium oxide (MgO) were added, it was found that methacrylic acid occupied the majority and methacrylic acid selective thermal decomposition was progressing.

[Example 10] Synthesis of a 2-hydroxyisobutyric acid derivative from a lactic acid derivative (see the reaction formula of the following chemical formula 12).

A stirrer was placed in a three-necked flask having an internal volume of 200 mL equipped with a cooling tube, a nitrogen introduction tube (three-way cock), a dropping funnel, and a septum cap, and nitrogen substitution was performed. DL-ethyl lactate (18.07 g, 150 mmol), triethylamine (31.6 mL, 230 mmol) and 150 ml of chloroform were added, and the flask was cooled to 0 ° C. using ice water. Trimethylsilyl chloride (29.2 mL, 230 mmol) was added to the dropping funnel, and this was slowly dropped into the flask. After completion of the dropwise addition, the reaction temperature was returned to room temperature, and the reaction was performed for 3 hours in a nitrogen atmosphere. The reaction was followed by GC gas chromatograph. After completion of the reaction, the reaction solution was washed with water three times, and the separated organic layer was dehydrated over anhydrous magnesium sulfate. The solution was filtered and chloroform was distilled off under reduced pressure. The resulting crude product was purified by a silica gel column. At that time, hexane: ethyl acetate (3: 1) was used as a solvent. As a colorless transparent liquid, 7.0 g of ethyl 2-trimethylsiloxypropanoate having a purity of 99% (GC purity) was obtained (yield: 25%). The physical properties were as follows.

¹ H-NMR: δ = 0.16 (9H, s, Si (CH ₃ ) ₃ )
), 1.27-1.30 (
3H, t, J = 7.3 Hz, CH ₃ ), 1.39 (3H, d, J = 6.5 Hz, CH ₃
), 4.15-4.22 (
2H, q, CH _2- ), 4.28-4.32 (1H, q, J = 6.8 Hz, CH)

A stirring bar was placed in an eggplant-shaped flask having an internal volume of 100 mL equipped with a nitrogen introduction tube (three-way cock), and nitrogen substitution was performed. 50 mL of ethyl 2-trimethylsiloxypropanoate (0.5 g, 2.6 mmol) and dehydrated THF
The flask was cooled to −84 ° C. (ethyl acetate + liquid nitrogen), lithium diisopropylamide solution (2.0 M heptane-tetrahydrofuran-ethylbenzene mixed solution) (1.3 mL, 2.6 mmol) was added, and 30 minutes. Stir in a nitrogen atmosphere. After 30 minutes, methyl iodide (0.4 mL, 5.2 mmol) was added and maintained at -84 ° C and stirred for 30 minutes. After completion of the reaction, 10% aqueous ammonium chloride solution was added to stop the reaction. The reaction solution was extracted with methylene chloride, washed twice with water, dried over anhydrous magnesium sulfate, the reaction solution was collected by filtration, and the solvent was distilled off under reduced pressure. The obtained crude product was purified with a silica gel column (solvent: hexane), and 0.1 g of the product 2-ethyl trimethylsiloxy-2-isobutyrate was obtained as a yellow liquid (yield: 19%). The physical properties were as follows.

¹ H-NMR: δ = 0.14 (9H, s, Si (CH ₃ ) ₃ )
), 1.27-1.30 (
3H, t, J = 7.3 Hz, CH ₃ ), 1.45 (6H, s, CH ₃ ),
4.14-4.19 (2H
, q, J = 7.0 Hz, CH _2- ), ¹³ C-NMR: δ = 2.01, 14.1, 28.6, 60.9, 75.0, 176.

[Examples 11 to 14] Thermal decomposition of poly (2-hydroxyisobutyric acid).
286.4 mg of poly (2-hydroxyisobutyric acid) and 16.2 mg (5% by weight) of calcium oxide (CaO) as a thermal decomposition catalyst were weighed into a sample bottle, dissolved in chloroform (3 ml), and stirred for 3 hours. This solution was transferred to a flat petri dish and allowed to stand overnight on a horizontal platform to prepare a cast film. The obtained film was dried for 4 hours while being reduced in pressure with a vacuum pump while being heated to 50 ° C. in a vacuum oven.

The thermal decomposition of poly (2-hydroxyisobutyric acid) was performed using a thermal decomposition-gas chromatograph / mass spectrometer (pyrolysis-GC / MS). About 0.1 mg of the above sample was put into a pyrolyzer, and pyrolysis was performed while the temperature was raised from 60 ° C. to the temperature shown in Table 3 at a rate of temperature rise of 9 ° C./min. Thermal decomposition products were separated by a GC / MS apparatus, and the amount of each component was measured as total ion count (TIC)%. The obtained results are shown in Table 3. From the results in Table 3, it was found that high methacrylic acid selective thermal decomposition was in progress.

[Reference Example 2] Measurement of equilibrium melting point of poly (2-hydroxyisobutyric acid).
Crystallization is promoted by repeatedly heating and cooling about 10 mg of poly (2-hydroxyisobutyric acid) synthesized in Reference Example 1 using a differential scanning calorimeter (DSC) in a nitrogen stream (20 mL / min). Then, the heat treatment temperature and the melting point were confirmed. As a result, the heat treatment temperature was gradually increased by 5 ° C. and finally held at 200 ° C. for 10 minutes, and then the melting point (Tm) was measured. As a result, the melting point of 205.4 ° C. was confirmed. Furthermore, the intersection (equilibration melting point) between the heat treatment temperature and the melting point rise curve was found to be 220 ° C.

[Examples 15 to 17] Steam decomposition of poly (2-hydroxyisobutyric acid).
About 10 mg of poly (2-hydroxyisobutyric acid) (Mn 44,000, Mw 61,000) was weighed into a sample bottle, and this was measured at 180 ° C., 200 ° C. in an atmospheric steam treatment apparatus (manufactured by Naomoto Kogyo). And steam at 210 ° C. was blown for 1 hour to perform a decomposition reaction with water vapor. Then, the sample was melt | dissolved in chloroform and the molecular weight was measured using the GPC apparatus. The results are shown in Table 4. From the results of the table, it was found that hydrolysis proceeds efficiently as the water vapor temperature increases.

According to the present invention, a 2-hydroxyisobutyric acid polymer excellent in heat resistance, structural stability and resource circulation characteristics is synthesized from a renewable resource as a raw material, and the 2-hydroxyisobutyric acid polymer is selectively used as a polymer raw material. It has become possible to carry out resource recycling by converting it into hydroxyisobutyric acid and / or a derivative thereof, or methacrylic acid and / or TMG. This is extremely effective in constructing a circulation system that makes effective use of renewable resources without depending on fossil resources.

[0005]
For this purpose, we conducted extensive research on the synthesis of this polymer from renewable resources, stabilization of physical properties, improvement of various physical properties, and selective conversion to raw materials. As a result, it has been found that 2-hydroxyisobutyric acid and its derivatives are synthesized from materials derived from renewable resources such as lactic acid and lactic acid derivatives. Moreover, it discovered that 2-hydroxyisobutyric acid polymer was stabilized by wash | cleaning 2-hydroxyisobutyric acid polymer obtained by superposition | polymerization of a 2-hydroxyisobutyric acid derivative using an acid and / or an acid anhydride. . Furthermore, 2-hydroxyisobutyric acid polymer can be selectively converted into 2-hydroxyisobutyric acid, a cyclic dimer of 2-hydroxyisobutyric acid, or methacrylic acid by using a specific decomposition method. I found an unexpected effect.
[0016]
And when the subject of the present invention manufactures 2-hydroxyisobutyric acid polymer in which biorecycling and chemical recycling are possible, using what was obtained from renewable resources as raw material 2-hydroxyisobutyric acid or its derivative, And it is achieved by the manufacturing method of 2-hydroxyisobutyric acid polymer characterized by stabilizing the 2-hydroxyisobutyric acid polymer obtained by superposition | polymerization by an acidic substance process. Further, another object of the present invention is to solvolyze the 2-hydroxyisobutyric acid polymer in the presence of water and / or alcohol when depolymerizing the 2-hydroxyisobutyric acid polymer as described above. To obtain 2-hydroxyisobutyric acid and / or a derivative thereof, or obtain a cyclic dimer of methacrylic acid and / or 2-hydroxyisobutyric acid by thermally decomposing the 2-hydroxyisobutyric acid polymer. It is achieved by a depolymerization method of 2-hydroxyisobutyric acid polymer characterized by
[0017]
In the present invention, a derivative of 2-hydroxyisobutyric acid means an alkyl estil of α-hydroxyisobutyric acid, or a cyclic dimer thereof (tetramethyl glycolide (TMG)), or an oligomer thereof. Means an alkyl ester of lactic acid, lactide, or an oligomer thereof.

[0006]
Effects of the Invention [0018]
According to the present invention, (1) it is possible to synthesize a high-performance polymer with improved problems of lactic acid polymer using renewable resources as a raw material. Further, (2) the treatment using an acidic substance can remove the polymerization initiator component remaining in the 2-hydroxyisobutyric acid polymer, and as a result, a 2-hydroxyisobutyric acid polymer having excellent stability can be obtained. . Furthermore, (3) water resistance, flexibility, further heat resistance, etc. can be added by blending with many other compatible / incompatible resins, and in addition, (4) heated steam and general By using a basic substance such as a typical transesterification catalyst and magnesium oxide, it is possible to selectively convert it into a polymer raw material, which is very useful as a resource recycling method.
MODE FOR CARRYING OUT THE INVENTION [0019]
The present invention synthesizes 2-hydroxyisobutyric acid and then 2-hydroxyisobutyric acid polymer using renewable resources as raw materials, stabilizes 2-hydroxyisobutyric acid polymer and improves physical properties, and further uses the resource recycling method It is about. In the present invention, the renewable resource refers to organic resources produced by plants, animals, or microorganisms, and secondary resources derived from these organic resources.
[0020]
Here, the organic resource means, for example, a primary fermentation product such as acetone, lactic acid, pyruvic acid, ethanol, ammonia, and the secondary resource derived therefrom is a lactic acid polymer derived from lactic acid; methyl lactate, Lactic acid esters such as ethyl lactate, butyl lactate and lactide; Pyruvate esters such as methyl pyruvate and ethyl pyruvate; and thermal decomposition products of organic resources such as methanol, carbon monoxide, carbon dioxide and hydrogen means.
[0021]
In the present invention, 2-hydroxyisobutyric acid is also called α-hydroxyisobutyric acid, 2-hydroxy-2-methylpropionic acid, 2,2-dimethylglycolic acid, or 2-hydroxy-2,2-dimethylacetic acid. Has a hydroxyl group

[0028]
[0088]
¹ H-NMR (CDCl 3)
(Ppm): 1.54 (s, CH3)
GPC (polystyrene conversion): Mn22000, MW32000
DSC: Tg = 70.8 ° C., Tm = 190.7 ° C.
[0089]
Example 3 and Comparative Example 1 Thermal stabilization of poly (2-hydroxyisobutyric acid) by treatment with dilute hydrochloric acid.
0.2087 g of poly (2-hydroxyisobutyric acid) (Mn8100, Mw12000) was taken in a 100 mL Erlenmeyer flask, and 20 mL of chloroform was added to this and stirred to dissolve. This solution was transferred to a separatory funnel and washed three times with 10 mL of 1N aqueous HCl. Thereafter, the chloroform solution was separated, and chloroform was distilled off from the solution under reduced pressure using a rotary evaporator. After distillation, the film-like polymer remaining at the bottom of the flask was taken out and dried under vacuum at 40 ° C. for 4 hours. The dried film-like sample was heated to 400 ° C. under a nitrogen gas stream (100 mL / min) using a TG / DTA at a temperature rising rate of 9 ° C./min. As a result, the weight loss due to thermal decomposition started at about 250 ° C and almost completely disappeared at 310 ° C. For comparison, untreated poly (2-hydroxyisobutyric acid) was used and heated with TG / DTA under similar conditions. As a result, the weight loss due to thermal decomposition started at about 235 ° C and almost completely disappeared at 295 ° C. Comparing the above results, it was confirmed that by washing poly (2-hydroxyisobutyric acid) with a 1N HCl aqueous solution, the thermal decomposition temperature of about 15 ° C. was increased and the heat was stabilized [0090].
[Examples 4 to 6 and Comparative Example 2] Preparation of blend film of poly (2-hydroxyisobutyric acid).
Poly (2-hydroxyisobutyric acid) (hereinafter sometimes abbreviated as PTMG) (Mn8100, Mw12000) and polycarbonate (PC, Mn11000, Mw34000), polybutyl succinate (PBS, Mn25600, Mw72000) in the amounts shown in Table 1 ) And polycaprolactone (PCL, Mw120,000) in a 20 mL sample tube, add 4 mL of chloroform, and stir overnight at room temperature to dissolve.

Claims (11)

When the 2-hydroxyisobutyric acid polymer is produced, the raw material 2-hydroxyisobutyric acid or a derivative thereof obtained from a renewable resource is used, and the 2-hydroxyisobutyric acid polymer obtained by polymerization is converted into an acidic substance. A process for producing a 2-hydroxyisobutyric acid polymer characterized by stabilization by treatment. 2. The renewable resource is lactic acid and / or a lactic acid derivative, and 2-hydroxyisobutyric acid and / or a derivative thereof is synthesized by methylation of the lactic acid and / or lactic acid derivative. Process for producing hydroxyisobutyric acid polymer. The 2-hydroxyisobutyric acid polymer according to claim 2, wherein a biomass-derived methylation reagent is used when synthesizing 2-hydroxyisobutyric acid and / or a derivative thereof by methylation of lactic acid and / or a lactic acid derivative. Manufacturing method. 2-hydroxyisobutyric acid or a derivative thereof obtained from a renewable resource is 2-hydroxyisobutyric acid or a cyclic dimer or oligomer obtained by depolymerizing a 2-hydroxyisobutyric acid polymer The method for producing a 2-hydroxyisobutyric acid polymer according to claim 1. The 2-hydroxyisobutyric acid polymer is stabilized by treating with an acidic substance using an organic acid, an inorganic acid, an organic acid anhydride, or a mixture thereof. Process for producing hydroxyisobutyric acid polymer. In depolymerizing the 2-hydroxyisobutyric acid polymer, the 2-hydroxyisobutyric acid polymer is solvolyzed in the presence of water and / or alcohol to obtain 2-hydroxyisobutyric acid and / or a derivative thereof, or Depolymerization of 2-hydroxyisobutyric acid polymer characterized by obtaining a cyclic dimer of methacrylic acid and / or 2-hydroxyisobutyric acid by thermal decomposition with or without using 2-hydroxyisobutyric acid polymer Method. The method for depolymerizing a 2-hydroxyisobutyric acid polymer according to claim 6, wherein the catalyst for thermally decomposing the 2-hydroxyisobutyric acid polymer is an alkaline earth metal compound and / or a transesterification catalyst. The method for depolymerizing a 2-hydroxyisobutyric acid polymer according to claim 6, wherein the 2-hydroxyisobutyric acid polymer is thermally decomposed with heated steam to obtain 2-hydroxyisobutyric acid and / or a derivative thereof. The 2-hydroxyisobutyric acid polymer constitutes a resin composition blended and / or complexed with another polymer, 2. -Depolymerization method of hydroxyisobutyric acid polymer. The method for depolymerizing a 2-hydroxyisobutyric acid polymer according to claim 6, wherein when the 2-hydroxyisobutyric acid polymer is thermally decomposed, an extruder having a vent structure is used. The method for depolymerizing a 2-hydroxyisobutyric acid polymer according to claim 6, wherein the 2-hydroxyisobutyric acid derivative is a cyclic dimer or oligomer of 2-hydroxyisobutyric acid.