HK1247946B - Polyester resin and method for producing same - Google Patents

Description

Polyester resin and method for producing the same

Technical Field

The present invention relates to a polyester resin and a method for preparing the same.

Background Art

Polyethylene terephthalate (hereinafter sometimes referred to as "PET") is a polyester resin widely used in films, sheets, hollow containers, and the like, due to its excellent transparency, mechanical strength, melt stability, solvent resistance, aroma retention, and recyclability. However, the glass transition temperature of PET is not always sufficiently high, and when thick-walled molded articles are obtained, transparency may be impaired due to its crystallinity. Therefore, modification by copolymerization is widely practiced.

For example, polyester resins containing 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, or pentacyclopentadecanedimethanol have been proposed as copolymer components for polyesters. Because tricyclodecane dimethanol and pentacyclopentadecanedimethanol are bulky and have rigid backbones, polyester resins containing them have a higher glass transition temperature, which can suppress crystallinity and improve the transparency of molded articles (see, for example, Patent Documents 1 and 2).

On the other hand, among aliphatic polyesters that do not contain any aromatic components, polyesters with an alicyclic structure exhibit excellent transparency and water resistance. Numerous methods have been proposed using alicyclic monomers, typified by 1,4-cyclohexanedimethanol. For example, Patent Document 3 discloses an aliphatic polyester composed of 1,4-cyclohexanedimethanol and 1,4-cyclohexanedicarboxylic acid. Furthermore, polyesters with a norbornane skeleton have been proposed for the purpose of improving the heat resistance of aliphatic polyesters (see, for example, Patent Documents 4 and 5).

Prior art literature

Patent Literature

Patent Document 1: Japanese Patent Application Laid-Open No. 58-174419

Patent Document 2: Japanese Patent Application Laid-Open No. 2003-119259

Patent Document 3: Japanese Patent Application No. 2007-517926

Patent Document 4: Japanese Patent Application Laid-Open No. 2001-64372

Patent Document 5: Japanese Patent Application Laid-Open No. 2001-64374

Summary of the Invention

Technical problem to be solved by the invention

The polyester resins described in Patent Documents 1 and 2 have aromatic dicarboxylic acid components, resulting in poor UV resistance and light transmittance. Furthermore, the aliphatic polyester described in Patent Document 3, while having good transparency, lacks high heat resistance. The polyester resins having a norbornane skeleton described in Patent Documents 4 and 5 exhibit good heat resistance compared to polyester resins using 1,4-cyclohexanedimethanol and 1,4-cyclohexanedicarboxylic acid as monomers, but further improvement is desired.

The present invention has been made in view of the above problems in the conventional technology, and an object of the present invention is to provide a polyester resin having excellent heat resistance and transparency.

Means for solving technical problems

The present inventors have conducted intensive studies to solve the above-mentioned technical problems and have found that the above-mentioned technical problems can be solved by including a structural unit having a specific alicyclic structure in the main skeleton.

That is, the present invention is as follows.

<1> A polyester resin comprising a structural unit represented by the general formula (1).

(In the above general formula (1), _R1 is a hydrogen atom, _CH3 or _C2H5 , _{and R2} and _R3 are each independently a hydrogen atom or _CH3 .)

<2> A method for producing a polyester resin, comprising the step of polymerizing a compound represented by the general formula (2).

₍ In the above general formula (2), _R1 is a hydrogen atom, _CH3 or _C2H5 , _R2 and _R3 are each independently a hydrogen atom or _CH3 , and X is a hydrogen atom or a hydrocarbon group having 4 or less carbon atoms which may or may not contain a hydroxyl group.)

Effects of the Invention

The polyester resin of the present invention is excellent in heat resistance and transparency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 shows the results of 1H-NMR measurement of the main reaction product obtained in the monomer synthesis example.

FIG2 shows the results of 13C-NMR measurement of the main reaction product obtained in the monomer synthesis example.

FIG3 shows the results of COSY-NMR measurement of the main reaction product obtained in the monomer synthesis example.

DETAILED DESCRIPTION

Hereinafter, a method for implementing the present invention (hereinafter referred to as "this embodiment") is described in detail. The following embodiments are for illustrating the present invention and are not intended to limit the present invention to the following contents. The present invention can be implemented by appropriately modifying it within the scope of its purpose.

(A) Polyester resin

The polyester resin of the present embodiment contains a structural unit represented by the following general formula (1) (hereinafter referred to as "structural unit (1)").

In the structural unit (1), R ₁ is a hydrogen atom, CH ₃ or C ₂ H ₅ , and R ₂ and R ₃ are each independently a hydrogen atom or CH ₃ .

Due to the above-mentioned structure, the polyester resin of this embodiment has excellent heat resistance and transparency. Due to its excellent heat resistance (high glass transition temperature) and transparency, the polyester resin of this embodiment is suitable as an optical material, electronic component, or medical material.

R ₁ is preferably a hydrogen atom or CH ₃ , and R ₂ and R ₃ are preferably a hydrogen atom.

The polyester resin of the present embodiment may contain other structural units in addition to the structural unit (1) within a range that does not impair the performance.

The above-mentioned other structural units are not particularly limited, and examples thereof include: structural units derived from aromatic dicarboxylic acids and/or their derivatives, such as terephthalic acid, isophthalic acid, phthalic acid, 1,3-naphthalene dicarboxylic acid, 1,4-naphthalene dicarboxylic acid, 1,5-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, 2,7-naphthalene dicarboxylic acid, 2-methylterephthalic acid, biphenyl dicarboxylic acid, and tetrahydronaphthalene dicarboxylic acid; structural units derived from succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, and nonane dicarboxylic acid; aliphatic dicarboxylic acids such as 2-hydroxy-1,4-dioxanedicarboxylic acid, 2-hydroxy-1,4-dioxanedicarboxylic acid, 2-hydroxy-1,4-dioxanedicarboxylic acid, 2-hydroxy-2 ... or a structural unit derived from ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, propylene glycol, neopentyl glycol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 1,2-decahydronaphthalene dimethanol, 1,3-decahydronaphthalene dimethanol, 1,4-decahydronaphthalene dimethanol, 1,5-decahydronaphthalene dimethanol, 1,6-decahydronaphthalene dimethanol, 2,7-decahydronaphthalene dimethanol, tetralin Structural units of diols such as dimethylol, norbornanediol, benzyl alcohol, 3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane, 1,4:3,6-dianhydro-D-sorbitol, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol; and structural units derived from oxoacids such as glycolic acid, lactic acid, hydroxybutyric acid, 2-hydroxyisobutyric acid, and hydroxybenzoic acid and/or their derivatives. Structural units having an aromatic ring or alicyclic structure are preferred from the perspectives of heat resistance and transparency.

The molecular weight of the polyester resin of this embodiment can be appropriately set in consideration of the desired performance and handling properties, and is not particularly limited. The polystyrene-equivalent weight-average molecular weight (Mw) is preferably 5,000 to 300,000, and more preferably 10,000 to 250,000. An Mw of 5,000 or greater tends to ensure better heat resistance, while an Mw of 300,000 or less tends to prevent an excessive increase in melt viscosity, facilitating extraction of the resin after production. Furthermore, since good flowability is ensured, injection molding in a molten state tends to be facilitated.

The limiting viscosity of the polyester resin of this embodiment (measured at 25°C using a mixed solvent of phenol and 1,1,2,2-tetrachloroethane in a mass ratio of 6:4) is not particularly limited. From the perspective of the moldability of the polyester resin of this embodiment, it is preferably 0.1 to 2.0 dL/g, and more preferably 0.2 to 1.5 dL/g. When the limiting viscosity is 0.1 dL/g or greater, sufficient mechanical strength tends to be ensured when melt-molding the polyester resin of this embodiment into a molded article such as a film. When the limiting viscosity is 1.5 dL/g or less, good melt flowability and moldability tend to be ensured, resulting in a molded article with excellent dimensional stability.

When the polyester resin of the present embodiment is further used, it is preferable to add an antioxidant, a release agent, an ultraviolet absorber, a fluidity modifier, a crystal nucleating agent, a reinforcing agent, a dye, an antistatic agent, an antibacterial agent, or the like.

(B) Method for producing the compound represented by general formula (2)

The polyester resin of the present embodiment can be obtained by, for example, polymerizing a compound represented by the following general formula (2).

In the above general formula (2), _R1 is a hydrogen atom, _CH3 or _{C2H5 , R2} and _R3 are each independently a hydrogen atom or _CH3 , and X is a hydrogen atom or a hydrocarbon group having 4 or less carbon atoms which may or may not contain a hydroxyl group.

In formula (2), _R1 is preferably a hydrogen atom or _CH3 . _R2 and _R3 are preferably a hydrogen atom. Examples of the hydrocarbon group include, but are not limited to, methyl, ethyl, propyl, butyl, vinyl, 2-hydroxyethyl, and 4-hydroxybutyl.

The compound represented by the general formula (2) in this embodiment can be synthesized using dicyclopentadiene or cyclopentadiene and an olefin having a functional group as raw materials, for example, by the route represented by the following formula (I).

(In formula (I), _R1 is a hydrogen atom, _CH3 , or _{C2H5 ; R2} and _R3 are each independently a hydrogen atom or _CH3 ; and X is a hydrogen atom or a hydrocarbon group having 4 or less carbon atoms which may or may not contain a hydroxyl group.)

[Production of a Monoolefin Having 13 to 21 Carbon Atoms Represented by General Formula (4) in Formula (I)]

The monoolefin having 13 to 21 carbon atoms represented by the general formula (4) can be produced, for example, by a Diels-Alder reaction of an olefin having a functional group and dicyclopentadiene.

Specific examples of the olefin having a functional group used in the Diels-Alder reaction include, but are not limited to, methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, vinyl methacrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl methacrylate, acrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, vinyl acrylate, 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, crotonic acid, methyl crotonic acid, ethyl crotonic acid, 3-methylcrotonic acid, methyl 3-methylcrotonic acid, and ethyl 3-methylcrotonic acid. Preferred olefins include methacrylic acid, methyl methacrylate, 2-hydroxyethyl methacrylate, acrylic acid, methyl acrylate, and 2-hydroxyethyl acrylate. More preferred olefins include methyl methacrylate and methyl acrylate.

Furthermore, examples of functional group-containing olefins used in the Diels-Alder reaction include acrylonitrile, methacrylonitrile, acrolein, and methacrolein. Using these olefins as raw materials, monoolefins represented by the general formula (4') can be produced, for example, via the pathways shown in the following formulas (II) and (III).

(In formula (II), R ₁ is a hydrogen atom or CH ₃ .)

(In formula (III), R ₁ is a hydrogen atom or CH ₃ .)

The dicyclopentadiene used in the Diels-Alder reaction is preferably of high purity, and the content of butadiene, isoprene, etc. is preferably reduced. The purity of dicyclopentadiene is preferably 90% or higher, more preferably 95% or higher. Furthermore, since dicyclopentadiene tends to depolymerize under heating conditions and become cyclopentadiene (so-called monocyclopentadiene), cyclopentadiene may be used instead of dicyclopentadiene. Furthermore, the monoolefin having 13 to 21 carbon atoms represented by the general formula (4) is believed to be substantially produced via the monoolefin having 8 to 16 carbon atoms represented by the following general formula (7) (the first-stage Diels-Alder reaction product). It is believed that the produced monoolefin of the general formula (7) reacts as a new dienophile with the cyclopentadiene (diene) present in the reaction system in the Diels-Alder reaction (the second-stage Diels-Alder reaction), thereby producing the monoolefin having 13 to 21 carbon atoms represented by the general formula (4).

(In formula (7), _R1 represents a hydrogen atom, _CH3 , or _{C2H5 ; R2} and _R3 each independently represent a hydrogen atom or _CH3 ; and X represents a hydrogen atom or a hydrocarbon group having 4 or less carbon atoms which may or may not contain a hydroxyl group.)

In order to effectively carry out the Diels-Alder reaction of the above-mentioned two stages, it is important to have cyclopentadiene in the reaction system. Therefore, as the reaction temperature, it is preferably 100° C. or more, more preferably 120° C. or more, and further preferably 130° C. or more. On the other hand, in order to suppress the by-products of high-boiling substances, it is preferably reacted at a temperature below 250° C. In addition, as the reaction solvent, hydrocarbons, alcohols, esters, etc., preferably aliphatic hydrocarbons with more than 6 carbon atoms, cyclohexane, toluene, xylene, ethylbenzene, mesitylene (mesitylene), propanol, butanol, etc., can also be used. In addition, AlCl ₃ and other known catalysts can also be added as needed.

As the reaction method of the Diels-Alder reaction, various reaction methods can be adopted, such as a batch method using a tank reactor, a semi-batch method in which a substrate or a substrate solution is supplied to a tank reactor under reaction conditions, and a continuous flow method in which a substrate is circulated in a tubular reactor under reaction conditions.

The reaction product obtained in the above-mentioned Diels-Alder reaction can be used directly as a raw material for the following hydroformylation reaction, but can be subjected to the following step after being purified by a method such as distillation, extraction, crystallization, etc.

[Production of a bifunctional compound having 14 to 22 carbon atoms represented by (3) in formula (I)]

The difunctional compound having 14 to 22 carbon atoms represented by the general formula (3) in the above formula (I) can be produced, for example, by subjecting a monoolefin having 13 to 21 carbon atoms represented by the general formula (4) to a hydroformylation reaction with carbon monoxide and hydrogen in the presence of a rhodium compound or an organophosphorus compound.

The rhodium compound used in the above-mentioned hydroformylation reaction can be any compound that forms a complex with an organophosphorus compound and exhibits hydroformylation activity in the presence of carbon monoxide and hydrogen, and the form of its precursor is not particularly limited. For example, a catalyst precursor such as dicarbonyl rhodium acetylacetonate (hereinafter referred to as Rh(acac)(CO) ₂ ), _Rh2O3 , _Rh4 (CO) ₁₂ , _Rh6 (CO) ₁₆ , _or Rh( _NO3 ) ₃ can be introduced into the reaction mixture simultaneously with the organophosphorus compound to form a catalytically active rhodium metal hydrogenated carbonylphosphorus complex in the reaction vessel. Alternatively, a rhodium metal hydrogenated carbonylphosphorus complex can be prepared in advance and introduced into the reactor. As a preferred specific example, there is a method in which Rh(acac)(CO) ₂ is reacted with an organophosphorus compound in the presence of a solvent and then introduced into the reactor simultaneously with an excess of the organophosphorus compound to form a catalytically active rhodium-organophosphorus complex.

To the surprise of the present inventors, a two-stage Diels-Alder reaction product having an internal olefin with a relatively large molecular weight, as represented by general formula (4), can be hydroformylated using a very small amount of rhodium catalyst. The amount of rhodium compound used in this hydroformylation reaction is preferably 0.1 to 60 micromoles, more preferably 0.1 to 30 micromoles, even more preferably 0.2 to 20 micromoles, and particularly preferably 0.5 to 10 micromoles per 1 mole of the monoolefin having 13 to 21 carbon atoms, represented by general formula (4), which serves as the substrate for the hydroformylation reaction. When the amount of rhodium compound used is less than 60 micromoles per 1 mole of the monoolefin having 13 to 21 carbon atoms, it can be practically evaluated that a recovery and recycling facility for the rhodium complex is unnecessary. Thus, according to this embodiment, the economic burden associated with recovery and recycling facilities can be reduced, and the cost of the rhodium catalyst can be lowered.

In the hydroformylation reaction of this embodiment, the organophosphorus compound used as a catalyst for the hydroformylation reaction with the rhodium compound is not particularly limited. Examples thereof include phosphines represented by the general formula P( _-Ra )(- _Rb )(- _Rc ) or phosphites represented by P( _-ORa )(- _ORb )(- _ORc ). Specific examples of _Ra , _Rb , and _Rc are not limited to the following groups. Examples include aryl groups that may be substituted with an alkyl group or alkoxy group having 1 to 4 carbon atoms, and alicyclic alkyl groups that may be substituted with an alkyl group or alkoxy group having 1 to 4 carbon atoms. Triphenylphosphine and triphenylphosphite are preferably used. The amount of the organophosphorus compound used is preferably 300 to 10,000 times the molar amount of the rhodium atom in the rhodium compound, more preferably 500 to 10,000 times the molar amount, further preferably 700 to 5,000 times the molar amount, and particularly preferably 900 to 2,000 times the molar amount. When the amount of the organophosphorus compound used is 300 times or more the molar amount of the rhodium atom, the stability of the rhodium metal hydrogenocarbonylphosphorus complex, which is the catalyst active material, tends to be sufficiently ensured, and as a result, good reactivity tends to be ensured. Furthermore, from the perspective of sufficiently reducing the cost of the organophosphorus compound, the amount of the organophosphorus compound used is preferably 10,000 times or less the molar amount of the rhodium atom.

The hydroformylation reaction can also be carried out without using a solvent. By using an inert solvent in the reaction, it can be more suitably carried out. The solvent that can be used in the hydroformylation reaction is not particularly limited as long as it is a solvent that dissolves the monoolefin having 13 to 21 carbon atoms represented by the general formula (4), dicyclopentadiene or cyclopentadiene, the above-mentioned rhodium compound, and the above-mentioned organic phosphorus compound. Specific examples, but not limited to the following substances, include: hydrocarbons such as aliphatic hydrocarbons, alicyclic hydrocarbons, and aromatic hydrocarbons; esters such as aliphatic esters, alicyclic esters, and aromatic esters; alcohols such as aliphatic alcohols and alicyclic alcohols; solvents such as aromatic halides. Among them, hydrocarbons are preferably used, and alicyclic hydrocarbons and aromatic hydrocarbons are more preferably used.

The temperature for conducting the hydroformylation reaction is preferably 40°C to 160°C, more preferably 80°C to 140°C. A reaction temperature of 40°C or higher tends to achieve a sufficient reaction rate and further suppress the residual amount of the raw material monoolefin. Furthermore, a reaction temperature of 160°C or lower tends to suppress the formation of byproducts derived from the raw material monoolefin or the reaction products, effectively preventing a decrease in the reaction efficiency.

When the hydroformylation reaction in the present embodiment is carried out, it is preferred to carry out the reaction under pressure of carbon monoxide (hereinafter sometimes referred to as "CO") and hydrogen (hereinafter sometimes referred to as " _H2 ") gas. In this case, CO and _H2 gas can be introduced into the reaction system independently, or can be introduced into the reaction system as a pre-prepared mixed gas. The molar ratio of CO and _H2 gas introduced into the reaction system (=CO/ _H2 ) is preferably 0.2 to 5, more preferably 0.5 to 2, and even more preferably 0.8 to 1.2. When the molar ratio of CO and _H2 gas is adjusted to the above range, there is a tendency that the reaction activity of the hydroformylation reaction or the selectivity of the target aldehyde becomes good. The CO and _H2 gas introduced into the reaction system decrease as the reaction proceeds, and therefore, when a pre-prepared mixed gas of CO and _H2 is used, the reaction control is sometimes simpler.

The reaction pressure of the hydroformylation reaction is preferably 1 to 12 MPa, more preferably 1.2 to 9 MPa, and even more preferably 1.5 to 5 MPa. A reaction pressure of 1 MPa or higher tends to achieve a sufficient reaction rate and effectively suppress the residual monoolefins used as starting materials. Furthermore, a reaction pressure of 12 MPa or lower eliminates the need for expensive equipment with excellent pressure resistance, thus achieving economic advantages. In particular, when conducting the reaction in a batch or semi-batch manner, it is necessary to discharge the CO and _H₂ gases and reduce the pressure after the reaction is completed. Lowering the pressure reduces the loss of CO and _H₂ gases, thus achieving economic advantages.

The hydroformylation reaction is preferably carried out in a batch or semi-batch manner. The semi-batch reaction can be carried out by adding a rhodium compound, an organophosphorus compound, and the above-mentioned solvent to a reactor, applying pressure or heating with CO/ _H₂ gas, etc., and then supplying a monoolefin or a solution thereof as a raw material to the reactor under known reaction conditions.

The reaction product obtained in the above-mentioned hydroformylation reaction may be used as a raw material for the following reduction reaction as it is, or may be subjected to the following step after being purified by, for example, distillation, extraction, crystallization, or the like.

[Production of a compound having 14 to 22 carbon atoms represented by formula (2)]

The compound having 14 to 22 carbon atoms represented by the general formula (2) in the above formula (I) can be produced by reducing the compound having 14 to 22 carbon atoms represented by the general formula (3) in the presence of a catalyst having hydrogenation ability and hydrogen.

In the above-mentioned reduction reaction, as a catalyst having hydrogenation ability, a catalyst containing at least one element selected from copper, chromium, iron, zinc, aluminum, nickel, cobalt, and palladium is preferably used. More preferred catalysts include Cu-Cr catalysts, Cu-Zn catalysts, Cu-Zn-Al catalysts, etc., and Raney-Ni catalysts, Raney-Co catalysts, etc. are also mentioned. More preferred catalysts are Cu-Cr catalysts and Raney-Co catalysts.

The usage amount of the hydrogenation catalyst is 1 to 100 mass % relative to the compound having 14 to 22 carbon atoms represented by the general formula (3) as the substrate, preferably 2 to 50 mass %, more preferably 5 to 30 mass %. By setting the usage amount of the catalyst to these ranges, hydrogenation reaction can be appropriately implemented. When the usage amount of the catalyst is 1 mass % or more, there is a tendency to fully react, and as a result, the yield of the target product can be fully ensured. In addition, when the usage amount of the catalyst is 100 mass % or less, there is a tendency that the balance of the catalyst amount for reaction and the improvement effect of the reaction speed becomes good.

The reaction temperature of the reduction reaction is preferably 60 to 200°C, more preferably 80 to 150°C. By setting the reaction temperature to 200°C or below, there is a tendency to suppress the occurrence of side reactions and decomposition reactions, and to obtain the target product in high yield. Furthermore, by setting the reaction temperature to 60°C or above, there is a tendency to complete the reaction within a suitable time, and to avoid a decrease in productivity or a decrease in the yield of the target product.

Regarding the reaction pressure of the above-mentioned reduction reaction, it is preferably 0.5 to 10 MPa as a hydrogen partial pressure, and more preferably 1 to 5 MPa. By setting the hydrogen partial pressure to below 10 MPa, there is a tendency to suppress the generation of side reactions or decomposition reactions and obtain the target product in a high yield. In addition, by setting the hydrogen partial pressure to above 0.5 MPa, there is a tendency to complete the reaction within an appropriate time, which can avoid a decrease in productivity or a decrease in the yield of the target product. In addition, an inert gas (such as nitrogen or argon) can also be coexisted in the reduction reaction.

A solvent may be used in the reduction reaction. Examples of the solvent used in the reduction reaction include aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, and alcohols. Among them, alicyclic hydrocarbons, aromatic hydrocarbons, and alcohols are preferred. Specific examples include cyclohexane, toluene, xylene, methanol, ethanol, and 1-propanol.

As the reaction method of the above-mentioned reduction reaction, various reaction methods can be adopted, such as a batch method using a tank reactor, a semi-batch method in which a substrate or a substrate solution is supplied to a tank reactor under reaction conditions, and a continuous flow method in which a substrate or a substrate solution is circulated in a tubular reactor filled with a molded catalyst under reaction conditions.

The reaction product obtained in the above-mentioned reduction reaction can be purified by, for example, distillation, extraction, crystallization, or the like.

(C) Method for producing polyester resin

The method for polymerizing the compound represented by general formula (2) in this embodiment to produce a polyester having a structural unit represented by general formula (1) is not particularly limited, and conventionally known methods for producing polyesters can be applied. Examples thereof include melt polymerization methods such as transesterification and direct esterification, and solution polymerization methods.

When producing the polyester resin of the present embodiment, the transesterification catalyst, esterification catalyst, polycondensation catalyst, etc. used in the production of conventional polyester resins can be used. These catalysts are not particularly limited, and examples thereof include compounds of metals such as zinc, lead, cerium, cadmium, manganese, cobalt, lithium, sodium, potassium, calcium, nickel, magnesium, vanadium, aluminum, titanium, antimony, germanium, and tin (for example, fatty acid salts, carbonates, phosphates, hydroxides, chlorides, oxides, alcoholates), or metallic magnesium. These substances can be used alone or in combination of two or more. As catalysts, compounds of manganese, cobalt, zinc, titanium, calcium, antimony, germanium, and tin are preferred among the above, and compounds of manganese, titanium, antimony, germanium, and tin are more preferred. The amount of these catalysts used is not particularly limited, and the amount as the metal component relative to the raw material of the polyester resin is preferably 1 to 1000 ppm, more preferably 3 to 750 ppm, and further preferably 5 to 500 ppm.

The reaction temperature in the polymerization reaction depends on the type of catalyst, the amount used, etc., and is generally selected within the range of 150°C to 300°C. Taking the reaction rate and resin coloration into consideration, it is preferably 180°C to 280°C. The pressure within the reaction layer is preferably adjusted to 1 kPa or less from the atmospheric pressure, and more preferably to 0.5 kPa or less.

During the polymerization reaction, a phosphorus compound may be added as desired. The phosphorus compound is not limited to the following substances, and examples thereof include phosphoric acid, phosphorous acid, phosphoric acid esters, and phosphite esters. The phosphoric acid ester is not limited to the following substances, and examples thereof include methyl phosphate, ethyl phosphate, butyl phosphate, phenyl phosphate, dimethyl phosphate, diethyl phosphate, dibutyl phosphate, diphenyl phosphate, trimethyl phosphate, triethyl phosphate, tributyl phosphate, and triphenyl phosphate. The phosphite is not limited to the following substances, and examples thereof include methyl phosphite, ethyl phosphite, butyl phosphite, phenyl phosphite, dimethyl phosphite, diethyl phosphite, dibutyl phosphite, diphenyl phosphite, trimethyl phosphite, triethyl phosphite, tributyl phosphite, and triphenyl phosphite. These substances may be used alone or in combination of two or more. The concentration of phosphorus atoms in the polyester resin of this embodiment is preferably 1 to 500 ppm, more preferably 5 to 400 ppm, and even more preferably 10 to 200 ppm.

As described above, the polyester resin of this embodiment may contain other structural units in addition to the structural unit (1) within a range that does not impair the performance. The structural units may be appropriately selected from structural units derived from dicarboxylic acids and/or their derivatives, diol structural units, units derived from monools, units derived from trivalent or higher polyols, units derived from monocarboxylic acids, units derived from polycarboxylic acids, and units derived from oxoacids other than the compound represented by the general formula (2). The conventionally known polyester production method is polymerized simultaneously with the compound represented by the general formula (2) using a conventionally known polyester production method. Examples of conventionally known polyester production methods include, but are not limited to, melt polymerization methods such as the transesterification method and the direct esterification method, and solution polymerization methods.

Furthermore, when producing the polyester resin of the present embodiment, various stabilizers such as an etherification inhibitor, a heat stabilizer, and a light stabilizer, a polymerization regulator, and the like may be used.

To the polyester resin of this embodiment, various additives and molding aids such as antioxidants, light stabilizers, ultraviolet absorbers, plasticizers, extenders, matting agents, drying regulators, antistatic agents, anti-settling agents, surfactants, flow improvers, drying oils, waxes, fillers, colorants, reinforcing agents, surface smoothing agents, leveling agents, curing reaction accelerators, and tackifiers may be added within a range that does not impair the purpose of this embodiment.

Example

The present invention will be described in further detail below with reference to Examples, but the scope of the present invention is not limited by these Examples.

(1) Weight average molecular weight (Mw)

The polyester resin was dissolved in tetrahydrofuran to a concentration of 0.2% by mass and measured by gel permeation chromatography (GPC) using standard polystyrene as a standard. GPC was performed using a TSKgel SuperHM-M column manufactured by Tosoh Corporation at a column temperature of 40°C. Tetrahydrofuran was allowed to flow as the eluent at a flow rate of 0.6 mL/min, and measurement was performed using an RI detector.

(2) Glass transition temperature (Tg)

The glass transition temperature of a polyester resin is measured as follows. Using a differential scanning calorimeter (Shimadzu Corporation, trade name: DSC/TA-60WS), approximately 10 mg of the polyester resin is placed in an aluminum, non-sealed container. The resulting melt is heated to 280°C at a rate of 20°C/min in a nitrogen gas stream (30 mL/min) and quenched to form a measurement sample. This sample is then measured under the same conditions, and the temperature at which the baseline before and after the DSC curve shifts by half the difference is defined as the glass transition temperature.

(3) Transparency

A polyester resin press-molded disc (3 mm thick) was used as a sample to measure the total light transmittance using a colorimeter/turbidity meter (manufactured by Nippon Denshoku Industries, Ltd., trade name: COH-400).

(4) Water vapor permeability coefficient (g·mm/m ² ·day)

The water vapor transmission rate of the coated substrate was measured using a water vapor transmission rate meter (manufactured by MOCON, trade name: PERMATRAN-W Model 1/50G) at 40°C and a relative humidity of 90%. The water vapor transmission coefficient of the coating film was calculated using the following formula:

1/R ₁ = 1/R ₂ + DFT/P

Here, assume that:

R ₁ = Water vapor transmission rate of the coated substrate (g/m ² ·day)

R ₂ = Water vapor transmission rate of substrate (g/m ² ·day)

DFT = coating thickness (mm)

P = water vapor permeability coefficient of the coating film (g·mm/m ² ·day).

(5) Photoelastic coefficient (m ² /N)

The birefringence was calculated from the change in load at a wavelength of 633 nm using an ellipsometer (M220, manufactured by JASCO Corporation) and an optical film produced by a casting method.

<Monomer Synthesis Example>

A 500 mL stainless steel reactor was charged with 173 g (2.01 mol) of methyl acrylate and 167 g (1.26 mol) of dicyclopentadiene, and the mixture was reacted at 195° C. for 2 hours. The reaction yielded a reaction liquid containing 96 g of a monoolefin represented by the following formula (4a). This liquid was purified by distillation, and a portion was used in the following reaction.

A 300 mL stainless steel reactor was used to hydroformylate the monoolefin represented by formula (4a) using a CO/ _H2 mixed gas (CO/ _H2 molar ratio = 1) and purified by distillation. 70 g of the monoolefin represented by formula (4a), 140 g of toluene, 0.50 g of triphenylphosphite, and 550 μL of a separately prepared toluene solution of Rh(acac)(CO) ₂ (concentration 0.003 mol/L) were added to the reactor. After replacement with nitrogen and the CO/ _H2 mixed gas three times each, the system was pressurized with a CO/ _H2 mixed gas and the reaction was carried out at 100°C and 2 MPa for 5 hours. After completion of the reaction, the reaction liquid was analyzed by gas chromatography, confirming that it contained 76 g of the compound represented by formula (3a) and 1.4 g of the monoolefin represented by formula (4a) (conversion 98%, selectivity 97%). The reaction liquid was then purified by distillation, and a portion was used in the following reaction.

In a 300 mL stainless steel reactor, 54 g of the compound represented by the formula (3a) purified by distillation, 7 mL of a sponge cobalt catalyst (manufactured by NIKKO RICA CORPORATION: R-400) and 109 g of toluene were added, the system was pressurized with hydrogen, and the reaction was carried out at 3 MPa and 100 ° C for 9 hours. After the reaction, the catalyst was filtered from the obtained slurry with a membrane filter having a pore size of 0.2 μm. Thereafter, the solvent was distilled off using an evaporator, and analyzed by gas chromatography and GC-MS, confirming that 51 g of the main product represented by the formula (2a) with a molecular weight of 250 was contained (main product yield 93%). It was further distilled and purified, and the main product was obtained.

＜Identification of products＞

The components obtained in the monomer synthesis example were subjected to NMR analysis. The NMR spectra are shown in Figures 1 to 3. The results of the GC-MS analysis shown below and the NMR analysis in Figures 1 to 3 confirmed that the main product obtained in the monomer synthesis example was the compound represented by the above formula (2a).

＜Analysis Method＞

1) Gas chromatography measurement conditions

Analytical equipment: Capillary gas chromatograph GC-2010Plus manufactured by Shimadzu Corporation

Analytical column: InertCap 1 manufactured by GL Sciences Co., Ltd. (30 m, 0.32 mm ID, film thickness 0.25 μm)

Column oven temperature: 60°C (0.5 minutes) - 15°C/minute - 280°C (4 minutes)

Detector: FID, temperature 280℃

2) GC-MS measurement conditions

·Analysis device: manufactured by Shimadzu Corporation, GCMS-QP2010Plus

Ionization voltage: 70eV

Analytical column: Agilent Technologies, DB-1 (30 m, 0.32 mm ID, film thickness 1.00 μm)

Column oven temperature: 60°C (0.5 minutes) - 15°C/minute - 280°C (4 minutes)

3) NMR measurement conditions

Device: JEOL Ltd., JNM-ECA500 (500MHz)

Measurement mode: 1H-NMR, 13C-NMR, COSY-NMR

Solvent: CDCl ₃ (heavy chloroform)

Internal standard substance: tetramethylsilane

<Example 1>

In a 200 mL polyester manufacturing apparatus equipped with a decompressor, a full-contractor, a cold hydrazine, a stirrer, a heating device, and a nitrogen inlet tube, 45 g of the compound represented by formula (2a) obtained in the monomer synthesis example and 0.007 g of tetrabutyl titanate were placed. The temperature was raised to 230° C. under a nitrogen atmosphere and then maintained for 1 hour. Thereafter, the temperature was slowly raised and the pressure was reduced, and finally polycondensation was carried out at 270° C. and below 0.1 kPa. The reaction was terminated at the moment of reaching an appropriate melt viscosity to obtain a polyester resin. The obtained polyester resin had a weight-average molecular weight of 26,000, a glass transition temperature of 167° C., and a total light transmittance of 91%.

<Example 2>

In a 30 mL polyester manufacturing apparatus equipped with a decompressor, a full-contractor, a cold hydrazine, a stirrer, a heating device, and a nitrogen inlet tube, 11.5 g of the compound represented by formula (2a) obtained in the monomer synthesis example and 0.005 g of tetrabutyl titanate were placed. The temperature was raised to 230°C under a nitrogen atmosphere and then maintained for 1 hour. Thereafter, the temperature was slowly raised and the pressure was reduced, and finally polycondensation was carried out at 270°C and below 0.1 kPa. The reaction was terminated at the moment of reaching an appropriate melt viscosity to obtain a polyester resin. The obtained polyester resin had a weight average molecular weight of 46,800, a glass transition temperature of 171°C, and a total light transmittance of 91%.

20 parts by mass of the obtained polyester resin and 80 parts by mass of tetrahydrofuran were mixed to form a coating solution with a solids concentration of 20% by mass. A 50 μm thick stretched polyethylene terephthalate film (Ester Film E5100 manufactured by Toyobo Co., Ltd.) was used as a substrate. The coating solution was applied to the substrate using a rod coater No. 20 and dried at 100°C for 60 minutes to form a coating film. The water vapor permeability of the resulting coating film was evaluated. The coating thickness was 5.7 μm, and the water vapor permeability coefficient calculated from the water vapor permeability was 1.14 g·mm/m ² ·day (40°C, 90% RH).

An optical film was produced using the polyester resin obtained above using the following casting method. Specifically, the polyester resin was dissolved in dichloromethane to a concentration of 5 wt%, cast onto a horizontal casting plate, and then volatilized while adjusting the amount of solvent evaporating from the casting solution to produce a transparent optical film with a thickness of 50 μm. The resulting optical film was thoroughly dried in a dryer at a temperature below the glass transition temperature, and then cut into 5 cm × 1 cm samples. The photoelastic coefficient was evaluated using an ellipsometer and the result was -0.4 × 10 ^-12 (m ² /N).

<Comparative Monomer Synthesis Example>

A 500 mL stainless steel reactor was charged with 95 g (1.10 mol) of methyl acrylate and 105 g (0.79 mol) of dicyclopentadiene, and the mixture was reacted at 195°C for 2 hours. A reaction solution containing 127 g of a monoolefin represented by the following formula (8) and 55 g of a monoolefin represented by formula (2a) was obtained. This solution was purified by distillation to obtain the monoolefin represented by formula (8), a portion of which was used in the following reaction.

A 500 mL stainless steel reactor was used to carry out a hydroformylation reaction of a monoolefin represented by formula (8) that had been purified by distillation using a CO/ _H2 mixed gas (CO/ _H2 molar ratio = 1). 100 g of the monoolefin represented by formula (8), 200 g of toluene, 0.614 g of triphenyl phosphite, and 200 μL of a separately prepared toluene solution of Rh(acac)(CO) ₂ (concentration 0.0097 mol/L) were added to the reactor. After replacement with nitrogen and a CO/ _H2 mixed gas three times each, the system was pressurized with a CO/ _H2 mixed gas and the reaction was carried out at 100°C and 2 MPa for 4.5 hours. After completion of the reaction, the reaction liquid was analyzed by gas chromatography, confirming that it contained 113 g of the difunctional compound represented by formula (9) (conversion 100%, selectivity 94%). The reaction liquid was then purified by distillation, and a portion was used in the following reaction.

In a 500 mL stainless steel reactor, 70 g of a difunctional compound represented by formula (9) purified by distillation, 14 mL of a sponge cobalt catalyst (R-400 manufactured by NIKKO RICA CORPORATION), and 210 g of toluene were added. The system was pressurized with hydrogen and the reaction was carried out at 3 MPa and 100° C. for 3.5 hours. After the reaction, the catalyst was filtered through a membrane filter with a pore size of 0.2 μm. Thereafter, the solvent was distilled off using an evaporator, and analysis was performed using GC-MS to confirm the presence of 69 g of a main product with a molecular weight of 184 (main product yield 98%). This was further purified by distillation to obtain the main product (10).

Comparative Example 1

A polyester resin was obtained by reacting in the same manner as in Example 2, except that the compound represented by formula (10) obtained in the comparative monomer synthesis example was used as the raw monomer and the final polycondensation temperature was set at 265°C. The obtained resin was then used to form a coating film in the same manner as in Example 2, and the water vapor transmission rate was measured and the water vapor transmission coefficient was calculated. The weight-average molecular weight, glass transition temperature, and water vapor transmission coefficient of the obtained resin are shown in Table 1. The total light transmittance of the obtained polyester resin was 91%.

[Table 1]

The water vapor permeability of Example 2 was reduced to 12.9 g/m ² ·day compared to 13.8 g/m ² ·day for the substrate alone. Furthermore, when evaluated using the water vapor permeability coefficient, the water vapor permeability of the resin of Example 2 was approximately 1/3 of that of the resin of Comparative Example 1.

This application is based on Japanese Patent Application No. 2015-107183 filed on May 27, 2015 and Japanese Patent Application No. 2016-061737 filed on March 25, 2016, the entire contents of which are incorporated herein by reference.

Possibility of industrial application

The polyester resin of the present invention is excellent in transparency and heat resistance and can be preferably used for materials requiring transparency or heat resistance. The present invention has great industrial significance.

Claims (2)

1. A polyester resin, wherein, Composed only of structural units represented by general formula (1), In the above general formula (1), _R1 is a hydrogen atom, _CH3 or _C2H5 , and _R2 and _R3 are hydrogen atoms or _CH3 independently _, respectively. 2. A method for manufacturing a polyester resin, wherein, The polyester resin is the polyester resin according to claim 1. It has a process for polymerizing the compound represented by general formula (2), In the above general formula (2), _R1 is a hydrogen atom, _CH3 or _C2H5 , _R2 and _R3 are hydrogen atoms or _CH3 independently, and X is a hydrocarbon group with or without hydroxyl groups _, which has 4 or fewer carbon atoms.