JP7452174B2 - Polyester resin and polyester resin blow molded products - Google Patents

Description

The present invention relates to a polyester resin and a blow-molded article made of polyester resin. The polyester resin contains a catalytic amount of an aluminum compound-derived component and a phosphorus compound-derived component, and reduces the amount of cyclic trimer in the polyester resin and reduces the amount of cyclic trimer when blow molding the polyester resin. Both have been achieved, and the solid phase polymerization activity has been improved.

Polyester resins represented by polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), etc. have excellent mechanical and chemical properties, and depending on the characteristics of each polyester resin, , for example, fibers for clothing and industrial materials, films and sheets for packaging, magnetic tape, optical, etc., bottles that are hollow molded products, casings for electrical and electronic parts, and other engineering plastic molded products. It is used in In particular, bottles made of saturated polyester resin such as PET have excellent mechanical strength, heat resistance, transparency, and gas barrier properties. It is widely used as

Typical polyester resins whose main constituents are units derived from aromatic dicarboxylic acids and alkylene glycols are made by, for example, PET, by esterification reaction of terephthalic acid or dimethyl terephthalate with ethylene glycol, or It is produced by producing an oligomer mixture such as bis(2-hydroxyethyl) terephthalate through a transesterification reaction, and then melt-polymerizing this at high temperature and under vacuum using a catalyst.

Conventionally, antimony compounds or germanium compounds have been widely used as polyester polymerization catalysts used in the polymerization of such polyester resins. Antimony trioxide, which is an example of an antimony compound, is a catalyst that is inexpensive and has excellent catalytic activity. During polymerization, metal antimony precipitates, causing darkening and foreign matter in the polyester resin, which also causes surface defects on the film. Furthermore, when used as a raw material for hollow molded products, it is difficult to obtain hollow molded products with excellent transparency. Under these circumstances, a polyester resin that does not contain antimony at all or does not contain antimony as a main catalyst component is desired.

Germanium compounds have already been put into practical use as catalysts other than antimony compounds that provide polyester resins that have excellent catalytic activity and do not have the above-mentioned problems. However, germanium compounds have the problem of being very expensive, and because they tend to distill out of the reaction system during polymerization, the catalyst concentration in the reaction system changes, making it difficult to control the polymerization. However, there are problems in using it as the main component of the catalyst.

Polymerization catalysts replacing antimony compounds or germanium compounds are also being investigated, and titanium compounds typified by tetraalkoxy titanates have already been proposed. However, polyester resins produced using titanium compounds are susceptible to thermal deterioration during melt molding, and there are also problems in that the polyester resins are significantly colored.

As described above, it is a polymerization catalyst whose main metal component is a metal other than antimony, germanium, and titanium, and it has excellent catalytic activity, excellent color tone and thermal stability, and excellent transparency of molded products. What is desired is a polymerization catalyst that provides a polyester resin with a polyester resin.

Blow molded articles are one of the uses of polyester resin. It is desired that the polyester resin blow-molded article has high transparency, and a catalyst consisting of an aluminum compound and a phosphorus compound has been disclosed as a new polymerization catalyst (for example, Patent Document 1 reference).

Furthermore, when a catalyst consisting of an aluminum compound and a phosphorus compound is used, it is necessary to suppress the generation of aluminum-based foreign substances in order to obtain a highly transparent polyester resin. A method for suppressing the generation of aluminum-based foreign matter is disclosed in Patent Document 2.

However, when the method of Patent Document 1 is used, there is a problem that the transparency of the resulting polyester resin varies depending on the amount and composition ratio of the aluminum compound and phosphorus compound that are the catalyst composition.

On the other hand, by carrying out the method of Patent Document 2, the above-mentioned problem of aluminum-based foreign substances can be suppressed, and a highly transparent polyester resin and a polyester resin blow-molded article can be obtained. However, for polyester resin blow-molded articles, the mold used during molding is not suitable for the cyclic trimer contained in the polyester resin (hereinafter referred to as CT) or the cyclic trimer generated during molding (hereinafter referred to as ΔCT). ), which causes staining of the mold, and this mold stain causes problems such as deterioration of transparency during continuous molding.

Japanese Patent Application Publication No. 2004-256633 Patent No. 5299655

The present invention was made against the background of the problems of the prior art described above, and uses a polymerization catalyst consisting of an aluminum compound and a phosphorus compound whose main metal components are metal components other than antimony, germanium, and titanium. In addition to having various stability characteristics such as color tone and heat resistance that are characteristic of polyester resins obtained using the polymerization catalyst, the production of aluminum-based foreign substances is suppressed and the transparency is high, and furthermore, the amount of CT is reduced. By achieving both this and the reduction of the ΔCT amount, mold contamination during the production of polyester resin blow-molded articles is suppressed, and a method for producing polyester resin using a polymerization catalyst consisting of an aluminum compound and a phosphorus compound. The objective is to improve one of the problems, that is, the solid phase polymerization rate is low.

The inventors of the present invention have made extensive studies to solve the above problems, and have succeeded in suppressing contamination of the mold due to CT and ΔCT during the production of polyester resin blow molded articles, which had not been solved with conventional techniques, and We have discovered a method to improve the quality and productivity of molded products, and have arrived at the present invention.

The above-mentioned CT amount and ΔCT amount exhibit antinomic behavior as described later. Therefore, the present inventors aimed to establish a method of achieving both reduction of CT and reduction of ΔCT, suppressing the total amount of CT and ΔCT, and suppressing mold contamination.
Patent Document 2 is a method established by focusing on the specific structure of a phosphorus compound present in a polyester resin. On the other hand, it was found that nine types of phosphorus compounds exist in polyester resins, including the structure focused on in Patent Document 2. Among the phosphorus compounds, there is a phosphorus compound bonded to the terminal hydroxyl group of the polyester represented by (Formula 1) to (Formula 3) below.
On the other hand, CT and ΔCT in polyester resins are generated by the cyclodepolymerization of the hydroxyl group end of the polyester, which attacks the third ester bond from the end, as shown in the chemical formula below. It is assumed that it is produced by a backbiting reaction.

Under the above circumstances, the present inventors have found that by increasing the amount of the compounds of (Formula 1) to (3) described above, and reducing the concentration of hydroxyl groups in the polyester, the hydroxyl group terminals can be The present invention was completed after conducting various studies, believing that the biting reaction can be suppressed and the generation of CT and ΔCT. Furthermore, as a result of the above study, we discovered that, as an unexpected effect, when a polyester polymerization catalyst consisting of an aluminum compound and a phosphorus compound is used, the problem of inferior solid phase polymerization activity compared to when an antimony catalyst is used can also be improved.

（５）アルミニウム元素の含有量が１３～２５ｐｐｍである上記（１）～（４）のいずれかに記載のポリエステル樹脂。
（６）アルミニウム元素に対するリン元素のモル比（Ｐ／Ａｌ）が１．５～３．５である上記（１）～（５）のいずれかに記載のポリエステル樹脂。
（７）上記（１）～（６）のいずれかに記載のポリエステル樹脂を用いて成形されたポリエステル樹脂製ブロー成形体。
（８）環状三量体の含有量が３６００ｐｐｍ以下である上記（７）に記載のポリエステル樹脂製ブロー成形体。 The present invention was completed based on the above findings, and has the following configurations (1) to (8).
(1) A polyester resin containing a catalytic amount of an aluminum compound-derived component and a phosphorus compound-derived component, wherein the polyester resin contains 85 mol% or more of ethylene terephthalate structural units, based on the total amount of phosphorus present in the polyester resin. A polyester resin characterized in that the total amount of phosphorus elements bonded to the terminal hydroxyl groups of the polyester is 42 to 60 mol%.
(2) The polyester resin according to (1) above, wherein the amount of cyclic trimer is 3300 ppm or less.
(3) The above (1) characterized in that when the polyester resin has a moisture content of 100 ppm or less and is melt-molded at a cylinder temperature of an injection molding machine of 290° C., the amount of increase in the cyclic trimer is 650 ppm or less. Or the polyester resin described in (2).
(4) Any of the above (1) to (3), wherein the structure of the phosphorus compound bonded to the terminal hydroxyl group of the polyester resin is at least one of the following (Formula 1) to (Formula 3): The polyester resin described in .

(5) The polyester resin according to any one of (1) to (4) above, which has an aluminum element content of 13 to 25 ppm.
(6) The polyester resin according to any one of (1) to (5) above, wherein the molar ratio of phosphorus element to aluminum element (P/Al) is 1.5 to 3.5.
(7) A polyester resin blow-molded article molded using the polyester resin according to any one of (1) to (6) above.
(8) The polyester resin blow molded article according to (7) above, wherein the content of the cyclic trimer is 3600 ppm or less.

The polyester resin according to the present invention is a polyester resin obtained using a polymerization catalyst consisting of an aluminum compound and a phosphorus compound whose main metal components are metal components other than antimony, germanium, and titanium. In addition to having various stability characteristics such as color tone and heat resistance that are characteristic of polyester resins produced by polyester resins, the production of aluminum-based foreign substances is suppressed and the resin has high transparency. In addition, a part of the terminal hydroxyl group of polyester is blocked by the phosphorus compound, and the generation of CT and ΔCT in the manufacturing process of polyester resin and the molding process of blow molding polyester resin is suppressed. The effect is that pollution can be suppressed. Furthermore, as an unexpected effect, when a polyester polymerization catalyst consisting of an aluminum compound and a phosphorus compound is used, the problem that the solid phase polymerization activity is inferior to that when an antimony catalyst is used can also be improved.

FIG. 2 is a correlation diagram between the temperature time product T×RT×(P/Al) of the final polymerization tank, CT, and ΔCT, which was determined from the results of Examples and Comparative Examples. It is a correlation diagram between the temperature time product T×RT×(P/Al) of the final polymerization tank and the total CT amount (=CT amount+ΔCT amount) obtained from the results of Examples and Comparative Examples. It is a correlation diagram between the temperature time product T x RT x (P/Al) of the final polymerization tank and the amount of end-blocked phosphorus compound determined from the results of Examples and Comparative Examples. It is a correlation diagram between the amount of end-capped phosphorus compound and the total CT amount (=CT amount+ΔCT amount) determined from the results of Examples and Comparative Examples. FIG. 2 is a correlation diagram between the amount of end-capped phosphorus compound and solid phase polymerization rate determined from the results of Examples and Comparative Examples.

The present invention will be explained in detail below.

(polyester resin)
The polyester resin of the present invention contains 85 mol% or more of ethylene terephthalate structural units, more preferably 90 mol% or more, and even more preferably 95 mol% or more. The polyester resin of the present invention preferably comprises a polycarboxylic acid and/or an ester-forming derivative thereof and a polyhydric alcohol and/or an ester-forming derivative thereof.

The polyhydric carboxylic acid is preferably a dicarboxylic acid, particularly preferably terephthalic acid, but dicarboxylic acids other than terephthalic acid may be included. Dicarboxylic acids other than terephthalic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, tetradecanedicarboxylic acid, and hexadecanedicarboxylic acid. , 1,3-cyclobutanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2,5-norbornanedicarboxylic acid, Saturated aliphatic dicarboxylic acids or ester-forming derivatives thereof such as dimer acid; unsaturated aliphatic dicarboxylic acids or ester-forming derivatives thereof such as fumaric acid, maleic acid, itaconic acid, orthophthalic acid; Isophthalic acid, terephthalic acid, 5-(alkali metal) sulfoisophthalic acid, diphenic 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, 4,4'-biphenyl dicarboxylic acid, 4,4'-biphenylsulfone dicarboxylic acid, 4,4'-biphenyl ether dicarboxylic acid, 1,2-bis(phenoxy)ethane-p, Examples include aromatic dicarboxylic acids such as p'-dicarboxylic acid, pamoic acid, anthracenedicarboxylic acid, and ester-forming derivatives thereof.

In addition to the dicarboxylic acid, a trivalent or higher-valent polycarboxylic acid may be used in combination in a small amount, and a tri- to tetravalent polycarboxylic acid is preferred. Examples of the polycarboxylic acids include ethanetricarboxylic acid, propanetricarboxylic acid, butanetetracarboxylic acid, pyromellitic acid, trimellitic acid, trimesic acid, 3,4,3',4'-biphenyltetracarboxylic acid, and these. Examples include ester-forming derivatives.

The polyhydric alcohol is preferably a diol, particularly preferably ethylene glycol, but diols other than ethylene glycol may be included. Diols other than ethylene glycol include 1,2-propylene glycol, 1,3-propylene glycol, diethylene glycol, triethylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 1 , 4-butylene glycol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexane Dimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 1,10-decamethylene glycol, 1,12-dodecanediol, polyethylene glycol, polytrimethylene glycol, poly Aliphatic glycols such as tetramethylene glycol; hydroquinone, 4,4'-dihydroxybisphenol, 1,4-bis(β-hydroxyethoxy)benzene, 1,4-bis(β-hydroxyethoxyphenyl)sulfone, bis (p-hydroxyphenyl)ether, bis(p-hydroxyphenyl)sulfone, bis(p-hydroxyphenyl)methane, 1,2-bis(p-hydroxyphenyl)ethane, bisphenol A, bisphenol C, 2,5-naphthalene Examples include aromatic glycols such as diols, glycols obtained by adding ethylene oxide to these glycols, and the like.

In addition to diols, trihydric or higher polyhydric alcohols or hydroxycarboxylic acids may be used in combination in small amounts, and trihydric to tetrahydric polyhydric alcohols are preferred. Examples of the polyhydric alcohol include trimethylolmethane, trimethylolethane, trimethylolpropane, pentaerythritol, glycerol, hexanetriol, and the like. Examples of hydroxycarboxylic acids include lactic acid, citric acid, malic acid, tartaric acid, hydroxyacetic acid, 3-hydroxybutyric acid, p-hydroxybenzoic acid, p-(2-hydroxyethoxy)benzoic acid, 4-hydroxycyclohexanecarboxylic acid, or these. Examples include ester-forming derivatives of.

Further, a combination of cyclic esters is also allowed. Examples of the cyclic ester include ε-caprolactone, β-propiolactone, β-methyl-β-propiolactone, δ-valerolactone, glycolide, and lactide.

Examples of ester-forming derivatives of polyhydric carboxylic acids or hydroxycarboxylic acids include alkyl esters and hydroxyalkyl esters of these compounds.

Examples of ester-forming derivatives of polyhydric alcohols include esters of polyhydric alcohols with lower aliphatic carboxylic acids such as acetic acid.

(polymerization catalyst)
The polyester resin of the present invention contains a catalytic amount of an aluminum compound-derived component and a phosphorus compound-derived component. That is, the polyester resin of the present invention is manufactured using a polymerization catalyst consisting of an aluminum compound and a phosphorus compound, and the amounts of the aluminum compound and the phosphorus compound to be added may be catalytic amounts. The catalytic amount is an effective amount for promoting the reaction between a polyhydric carboxylic acid and/or its ester-forming derivative and a polyhydric alcohol and/or its ester-forming derivative, and specifically, The catalyst amount may be such that a predetermined amount of aluminum element and phosphorus element, which will be described later, remain in the resin.

(aluminum compound)
The aluminum compound constituting the above polymerization catalyst is not limited as long as it is soluble in the solvent, but aluminum formate, aluminum acetate, basic aluminum acetate, aluminum propionate, aluminum oxalate, aluminum acrylate, aluminum laurate, stearic acid Carboxylate salts such as aluminum, aluminum benzoate, aluminum trichloroacetate, aluminum lactate, aluminum citrate, aluminum tartrate, aluminum salicylate; aluminum chloride, aluminum hydroxide, aluminum hydroxide chloride, aluminum nitrate, aluminum sulfate, aluminum carbonate, phosphorous Inorganic acid salts such as aluminum acid and aluminum phosphonate; Aluminum alkoxides such as aluminum methoxide, aluminum ethoxide, aluminum n-propoxide, aluminum iso-propoxide, aluminum n-butoxide, and aluminum t-butoxide; aluminum acetylacetonate; Chelate compounds such as aluminum ethyl acetoacetate and aluminum ethyl acetoacetate diiso-propoxide; organoaluminum compounds such as trimethylaluminum and triethylaluminum, and their partial hydrolysates; reactions consisting of aluminum alkoxides and aluminum chelate compounds with hydroxycarboxylic acids; Examples include aluminum oxide, ultrafine aluminum oxide, aluminum silicate, and composite oxides of aluminum with titanium, silicon, zirconium, alkali metals, alkaline earth metals, and the like. Among these, at least one selected from carboxylates, inorganic acid salts, and chelate compounds is preferred, and among these, aluminum acetate, basic aluminum acetate, aluminum chloride, aluminum hydroxide, aluminum hydroxide chloride, and aluminum acetylacetate are preferred. At least one selected from aluminum acetate, basic aluminum acetate, aluminum chloride, aluminum hydroxide, and aluminum hydroxide chloride is more preferable, and at least one selected from aluminum acetate and basic aluminum acetate is more preferable. The most preferred is at least one of the following.

The aluminum compound is preferably an aluminum compound that is soluble in a solvent such as water or glycol. Solvents that can be used in the present invention are water and alkylene glycols. Examples of alkylene glycols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, trimethylene glycol, ditrimethylene glycol, tetramethylene glycol, ditetramethylene glycol, neopentyl glycol, etc. . Preferably, it is at least one selected from ethylene glycol, trimethylene glycol, and tetramethylene glycol, and more preferably ethylene glycol. It is preferable to use a solution in which an aluminum compound is dissolved in water or ethylene glycol because the effects of the present invention can be significantly exhibited. From the viewpoint of solubilization, the aluminum compound is preferably at least one selected from aluminum acetate, basic aluminum acetate, aluminum chloride, aluminum hydroxide chloride, and aluminum acetylacetonate; , and at least one selected from aluminum hydroxide chloride, and most preferably at least one selected from aluminum acetate and basic aluminum acetate.

The amount of the aluminum compound used is preferably such that the aluminum element is 13 to 25 ppm based on the total mass of the polyester resin obtained. More preferably it is 14 to 20 ppm. If the aluminum element content is less than 13 ppm, the polymerization activity may decrease. On the other hand, if it exceeds 25 ppm, the amount of aluminum-based foreign matter may increase.

(phosphorus compound)
The phosphorus compound constituting the polymerization catalyst of the present invention is not particularly limited, but it is preferable to use a phosphonic acid-based compound or a phosphinic acid-based compound because it has a large effect of improving catalyst activity. Among these, phosphonic acid-based compounds are preferably used. This is more preferable because it has a particularly large effect of improving catalyst activity.

Among the above phosphorus compounds, phosphorus compounds having a phenol structure in the same molecule are preferred. There are no particular limitations as long as the phosphorus compound has a phenol structure, but one or two selected from the group consisting of phosphonic acid compounds that have a phenol structure in the same molecule, and phosphinic acid compounds that have a phenol structure in the same molecule. Use of the above compounds is preferable because the effect of improving the catalytic activity is large, and use of one or more phosphonic acid compounds having a phenol structure in the same molecule is more preferable because the effect of improving the catalytic activity is very large.

In addition, examples of phosphorus compounds having a phenol structure in the same molecule include compounds represented by P(=O)R ¹ (OR ² ) (OR ³ ) and P(=O)R ¹ R ⁴ (OR ² ). can be mentioned. R ¹ represents a hydrocarbon group having 1 to 50 carbon atoms containing a phenol moiety, a substituent such as a hydroxyl group, a halogen group, an alkoxyl group or an amino group, and a hydrocarbon group having 1 to 50 carbon atoms containing a phenol structure. R ⁴ represents hydrogen, a hydrocarbon group having 1 to 50 carbon atoms, a hydrocarbon group having 1 to 50 carbon atoms containing a substituent such as a hydroxyl group, a halogen group, an alkoxyl group, or an amino group. R ² and R ³ each independently represent hydrogen, a hydrocarbon group having 1 to 50 carbon atoms, or a hydrocarbon group having 1 to 50 carbon atoms containing a substituent such as a hydroxyl group or an alkoxyl group. However, the hydrocarbon group may include a branched structure, an alicyclic structure such as cyclohexyl, or an aromatic ring structure such as phenyl or naphthyl. The ends of R ² and R ⁴ may be bonded to each other.

Examples of phosphorus compounds having a phenol structure in the same molecule include p-hydroxyphenylphosphonic acid, dimethyl p-hydroxyphenylphosphonate, diethyl p-hydroxyphenylphosphonate, diphenyl p-hydroxyphenylphosphonate, bis(p- hydroxyphenyl)phosphinic acid, methyl bis(p-hydroxyphenyl)phosphinate, phenyl bis(p-hydroxyphenyl)phosphinate, p-hydroxyphenylphenylphosphinic acid, methyl p-hydroxyphenylphenylphosphinate, p-hydroxyphenylphenyl Phenyl phosphinate, p-hydroxyphenylphosphinic acid, methyl p-hydroxyphenylphosphinate, phenyl p-hydroxyphenylphosphinate, 3,5-di-tert-butyl-4-hydroxy represented by the following (formula 4) Examples include dialkyl benzylphosphonate. As the phosphorus compound having a phenol structure in the same molecule, a phosphorus compound having a hindered phenol structure is particularly preferable, and among them, 3,5-di-tert-butyl-4- shown below (Formula 4) is preferable. Dialkyl hydroxybenzylphosphonate is preferred.

（（化式４）において、Ｘ¹、Ｘ²は、それぞれ、水素、炭素数１～４のアルキル基を表す。）

(In (Formula 4), X ¹ and X ² represent hydrogen and an alkyl group having 1 to 4 carbon atoms, respectively.)

The number of carbon atoms in the alkyl group of X ¹ and X ² is preferably 1 to 4, more preferably 1 to 2. In particular, the ethyl ester having 2 carbon atoms is preferred because Irganox 1222 (manufactured by BASF) is commercially available and can be easily obtained.

The amount of the phosphorus compound used is preferably such that the phosphorus element is 25 to 60 ppm based on the total mass of the polyester resin obtained. More preferably it is 30 to 50 ppm. If the phosphorus element content is less than 25 ppm, there is a risk that the polymerization activity will decrease and the amount of aluminum-based foreign matter will increase. On the other hand, if it exceeds 60 ppm, it becomes difficult to achieve both a reduction in CT amount and a reduction in ΔCT amount, and the amount of phosphorus compound added increases, which may increase catalyst cost.

In the present invention, it is preferable that the phosphorus compound is heat-treated in a solvent. The solvent to be used is not limited as long as it is at least one selected from the group consisting of water and alkylene glycol, but as the alkylene glycol, it is preferable to use a solvent that dissolves a phosphorus compound, such as ethylene glycol. It is more preferable to use glycol, which is a constituent component of polyester resin. The heat treatment in the solvent is preferably performed after the phosphorus compound has been dissolved, but it is not necessary to completely dissolve the phosphorus compound.

The temperature of the heat treatment is not particularly limited, but is preferably 20 to 250°C, more preferably 150 to 200°C.

The concentration of the phosphorus compound solution during the heat treatment is preferably 5 to 15% by mass.

The above heat treatment improves the activity of the polymerization catalyst when used in combination with the aluminum compound, and reduces the amount of foreign matter produced due to the polymerization catalyst.

In the above heat treatment, a part of the 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid dialkyl ester, which is the phosphorus compound represented by Formula 4 used in the present invention, undergoes a structural change. For example, the t-butyl group is eliminated, the ethyl ester group is hydrolyzed, and the hydroxyethyl transesterification structure is changed. Therefore, in the present invention, as a phosphorus compound, in addition to the 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid dialkyl ester shown in (Formula 4), structural changes as shown in Table 1 are used. Also included are phosphorus compounds. The amount of each phosphorus compound listed in Table 1 in an ethylene glycol solution can be determined by measuring the P-NMR spectrum of the solution.

Therefore, as the phosphorus compound in the present invention, in addition to diethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate, 3,5-di-tert-butyl-4-hydroxybenzyl shown in Table 1 above may be used. Also included are modified forms of diethyl phosphonate.

(Phosphorus compound structure in polyester resin)
In the polyester resin produced using diethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate and its modified product as a phosphorus compound, the above (Formula 1) to (Formula 3) are present. It exists in nine types of structures, including three types. Table 2 shows the structures of nine types of phosphorus compounds. In addition, the nine types of phosphorus compound structures described in Table 2 are also included in the polyester resin blow molded article described later, as in the polyester resin.

The technique disclosed in Patent Document 2 mentioned above is a technique established by focusing on (Formula 7) in Table 2 above.

In the present invention, as mentioned above, it is believed that the generation of CT and ΔCT can be suppressed by increasing the total amount of phosphorus compounds bonded to the terminal hydroxyl groups of the polyesters represented by Formulas 1 to 3. It is based on ideas.

Therefore, in the present invention, 42 to 60 mol% of the total amount of phosphorus present in the polyester resin is present bonded to the hydroxyl group terminal of the polyester, that is, based on the total amount of phosphorus present in the polyester resin. The total amount of phosphorus elements contained in (Formula 1) to (Formula 3) is 42 to 60 mol% or more. The lower limit is preferably 44 mol% or more, and the upper limit may be 100 mol% since higher is preferable, but due to technical difficulties, the upper limit is 60 mol% and should be 55 mol%. is preferable, and more preferably 50 mol%. In addition, the phosphorus compound bonded to the terminal hydroxyl group of the polyester is sometimes referred to as an end-capped phosphorus compound.

By satisfying the above range, it is possible to achieve both a reduction in the amount of CT and a reduction in the amount of ΔCT.
Furthermore, as an unexpected effect, the problem of polyester polymerization catalysts made of aluminum compounds and phosphorus compounds, which is inferior in solid phase polymerization activity compared to antimony catalysts, can be improved. It is not clear why the solid-phase polymerization activity is improved by increasing the amount of end-blocking phosphorus compound in polyester, but the reaction activity between the hydroxyl group end and the end-blocking phosphorus compound in the solid-phase polymerization reaction is It is speculated that this is because the reaction activity is higher than that with blocked phosphorus compounds.

(Aluminum/phosphorus ratio in polyester resin)
In the polyester resin of the present invention, the molar ratio of phosphorus element to aluminum element (hereinafter referred to as P/Al ratio) is preferably 1.5 to 3.5. The lower limit is more preferably 1.6 or more, and the upper limit is more preferably 3.0 or less, still more preferably 2.4 or less. If the P/Al ratio is less than 1.5, it becomes difficult to achieve both a reduction in CT amount and a reduction in ΔCT amount, and the amount of aluminum-based foreign matter may increase. On the other hand, if the P/Al ratio exceeds 3.5, it becomes difficult to achieve both a reduction in CT amount and a reduction in ΔCT amount, and the amount of phosphorus compound added increases, which may increase catalyst cost. be. Moreover, polymerization activity also decreases.

(CT amount in polyester resin)
It is preferable that the amount of CT contained in the polyester resin of the present invention is 3300 ppm or less. More preferably it is 3200 ppm or less, and still more preferably 3100 ppm or less. Although the lower limit is not limited, it is approximately 2500 ppm due to technical difficulties. If the CT amount exceeds 3300 ppm, mold staining during molding increases, which is not preferable.

(ΔCT amount during melt molding of polyester resin)
When the polyester resin of the present invention is melt-molded with a moisture content of 100 ppm or less and an injection molding machine cylinder temperature of 290° C., the ΔCT amount is preferably 650 ppm or less. More preferably it is 500 ppm or less, and still more preferably 400 ppm. The lower limit is preferably 0 ppm, but due to technical difficulties, it is approximately 200 ppm. If the ΔCT amount exceeds 650 ppm, mold contamination during molding increases, which is not preferable.

(Polyester resin blow molded body)
It is important that the blow molded article of the present invention is a polyester resin blow molded article molded using the above polyester resin. By using the above polyester resin, both the CT amount and the ΔCT amount can be suppressed, so that contamination of the mold during molding can be suppressed.

The method for producing the polyester resin blow molded article in the present invention is not limited. For example, the process of molding the preform, the process of crystallizing the spout, the process of reheating the preform, the process of blow-stretching the reheated preform in a mold, and the process of blow-stretching the blow-stretched hollow molded body. A manufacturing method including a step of heat setting in a heated mold is mentioned.

Hollow containers made by blow molding PET are used as containers for various purposes. In particular, they are widely used as containers (bottles) for beverages such as juice, tea, and mineral water.

These beverage containers are broadly classified into pressure-resistant bottles for carbonated drinks, aseptic bottles for aseptic filling, and heat-resistant bottles for high-temperature filling.

Since heat-resistant bottles are filled with materials at a high temperature of around 80°C, the bottles must also be heat resistant so that they do not deform at this filling temperature. Heat resistance is achieved by crystallizing the mouth and body of the bottle. ing.

To crystallize the body, after heating the preform, blow stretching is performed in a mold heated to 130 to 180°C, and the bottle is held in the mold for about 0.5 to 10 seconds. The crystallization of the parts is increased.

At this time, oligomers such as CT in PET and ΔCT generated during blow molding migrate to the mold surface and contaminate the mold surface, and as molding is repeated, contamination accumulates and after a certain number of moldings. The resulting bottle became cloudy and had no commercial value, so the mold had to be cleaned.

Cleaning the mold requires manual wiping using a solvent, and since large-scale commercial blow molding machines are equipped with multiple blow molding molds, it takes time to clean all the molds. It took several hours to a full day, and improvements were required in terms of decreased productivity and work environment.

Therefore, in the present invention, the content of the cyclic trimer in the blow molded product is preferably 3600 ppm or less. More preferably it is 3500 ppm or less. Although it is preferable that the content of the cyclic trimer in the blow molded product is small, due to technical difficulties, it is, for example, 1000 ppm or more, preferably 2000 ppm or more, and more preferably 2700 ppm or more.

In the present invention, resins other than polyethylene terephthalate may be included in order to improve the crystallization properties of the polyester resin. The resin other than polyethylene terephthalate is preferably at least one resin selected from the group consisting of polyolefin resins, polyamide resins, polyacetal resins, and polybutylene terephthalate resins. The blending amount of the resin other than polyethylene terephthalate is preferably 0.1 ppb to 1000 ppm (based on mass), more preferably 0.3 ppb to 100 ppm (based on mass), still more preferably 0.5 ppb to 1 ppm (based on mass), and particularly preferably It is 0.5 ppb to 45 ppb (based on mass).

The method of blending the above-mentioned resin with the polyester resin is preferably a method that allows uniform mixing, such as addition during the polyester resin manufacturing process or dry blending with the polyester resin after manufacturing. is preferably added at any stage of the esterification reaction or transesterification reaction or at the beginning of the polymerization reaction process during preparation of the raw material slurry. Furthermore, a method of bringing the PET chip into contact with the crystalline resin member is also a preferred form.

(Means for achieving both reduction in CT amount and reduction in ΔCT amount)
In the present invention, in order to achieve both a reduction in CT amount and a reduction in ΔCT, it is preferable that the amount of end-capped phosphorus compounds in the phosphorus compounds present in the polyester resin is large. Therefore, in the method for producing the polyester resin of the present invention, an aluminum compound and a phosphorus compound are used as polymerization catalysts, and two or more polymerization tanks (a polymerization reaction tank for performing polycondensation after the esterification reaction/ester exchange reaction step) are used. ), and the polymerization in the final polymerization tank satisfies the conditions of formula (I) below, and a solid phase polymerization step in which solid phase polymerization is performed after the melt polymerization step. is preferred. In this specification, the term "polymerization tank" refers to a polymerization tank that performs polycondensation after the esterification reaction/ester exchange reaction process.
410≦T×RT×(P/Al)≦580… (I)
[In the above formula (I), T is the temperature (° C.) of the final polymerization tank, RT is the residence time (hours) of the final polymerization tank, and P/Al is the molar ratio of the phosphorus element to the aluminum element in the polyester resin. ]
The end-blocking type phosphorus compound is controlled by the product of the temperature and residence time of the final polymerization tank in the melt polymerization method of polyester resin and the molar ratio of phosphorus element and aluminum element remaining in the polyester resin. Therefore, in the present invention, the product of the final polymerization tank temperature and residence time is important in the above melt polymerization method. The number of polymerization tanks is more preferably 2 to 5, even more preferably 3 to 4, and most preferably 3.

The value of the above formula (I) is more preferably 420 or more, even more preferably 450 or more, and particularly preferably 500 or more. Further, the value of the above formula (I) is more preferably 560 or less, and even more preferably 530 or less. If the value of the above formula (1) exceeds 580 or is less than 410, the total amount of CT amount and ΔCT amount increases due to the decrease in the amount of end-capped phosphorus compound, and when molding polyester resin. mold contamination may increase.

There are no particular limitations on the method for producing the polyester resin of the present invention, and examples include direct esterification of a polycarboxylic acid including terephthalic acid and a polyhydric alcohol, or a method of directly esterifying a polyhydric alcohol with an alkyl ester such as terephthalic acid. An oligomer of terephthalic acid or the like and a polyhydric alcohol is obtained by the transesterification method, and then melt polymerized under normal pressure or reduced pressure to obtain a polyester resin. At this time, an esterification catalyst or the above-mentioned polymerization catalyst can be used if necessary.

(Method for melt polymerization of polyester resin)
In the method for producing the polyester resin of the present invention obtained using a polymerization catalyst consisting of an aluminum compound and a phosphorus compound, the influence of the composition of the polyester oligomer supplied to the polymerization tank is more important than that of antimony, germanium, and titanium-based catalysts. received greatly. Therefore, it is preferable to carry out the following method.

The method for melt polymerizing polyester resin according to the present invention uses a polyester resin polymerization catalyst consisting of an aluminum compound and a phosphorus compound as a catalyst, and sets the above-mentioned melt polymerization conditions and P/Al (molar ratio) in the polyester resin to a specific range. Except for this point, the method can be carried out by a method including conventionally known steps. For example, when producing PET, there is a direct esterification method in which terephthalic acid and ethylene glycol, and if necessary, other copolymerization components are directly reacted, water is distilled off and esterified, and then polymerization is carried out under reduced pressure. Alternatively, it is produced by a transesterification method in which dimethyl terephthalate, ethylene glycol, and if necessary other copolymerization components are reacted, methyl alcohol is distilled off, transesterification is performed, and then polymerization is carried out under reduced pressure. In order to promote crystallization before solid phase polymerization, the melt-polymerized polyester resin may be allowed to absorb moisture and then heated and crystallized, or water vapor may be directly blown onto the polyester resin chips for heating and crystallization.
The melt polymerization reaction is preferably carried out in a continuous reaction apparatus. A continuous reactor is a system in which the reaction vessel for esterification or transesterification reaction and the melt polymerization reaction vessel are connected via piping, and raw materials are continuously fed into each reaction vessel without emptying. This method involves transferring the resin to the reactor and extracting the resin from the melt polymerization reaction vessel. In this case, "continuous" does not necessarily mean that raw materials are completely input and withdrawn at all times, but intermittently, such as in small amounts, for example, approximately 1/10 of the amount of the reaction vessel, that is performed from input to raw materials. It may be something.
In any of these methods, the esterification reaction or the transesterification reaction may be carried out in one step or may be carried out in multiple steps. The melt polymerization reaction may be carried out in one step or may be carried out in multiple steps, preferably 2 to 5 steps, more preferably 3 to 4 steps, and 3 steps. It is even more preferable.

In the present invention, the set value of the carboxyl end group concentration of the polyester oligomer supplied to the polymerization step is preferably 800 to 1500 eq/ton. More preferably 800 to 1450 eq/ton. By setting the concentration of carboxyl end groups of the polyester oligomer within the above range, the activity of the polymerization catalyst can be fully brought out.

Further, in the present invention, the ratio of the hydroxyl end group concentration to the total end group concentration of the polyester oligomer supplied to the polymerization step is preferably 45 to 70 mol%, more preferably 47 to 68 mol%.

The carboxyl end group concentration of the oligomer supplied to the polymerization step is preferably within the above-mentioned preferred range, and the variation in the carboxyl end group concentration is preferably within ±6% of the set value. It is more preferably within ±5%, even more preferably within ±4%, and particularly preferably within ±3%. If the carboxyl terminal group concentration fluctuation exceeds ±6%, there is a risk that the uniformity of quality of the obtained polyester resin will deteriorate. On the other hand, the lower limit is most preferably ±0% with no fluctuation, but from the point of view of cost performance, ±0.2% is preferable, and ±0.5% is more preferable.

For example, when carrying out an esterification reaction using a plurality of esterification reactors, in order to suppress fluctuations in the carboxyl end group concentration of the polyester oligomer at the outlet of the final esterification reactor, which is the oligomer supplied to the polymerization process, the first It is important to suppress fluctuations in the concentration of carboxyl end groups in the polyester oligomer at the outlet of the esterification reaction tank.If fluctuations in these characteristics are suppressed, fluctuations in the concentration of carboxyl end groups in the polyester oligomer at the exit of the final esterification reaction tank will be greatly reduced. Can be made smaller. In addition, fluctuations in the carboxyl end group concentration of the polyester oligomer at the outlet of the first esterification reaction tank are largely influenced by fluctuations in the amount of heat per unit time of the reactants staying in the first esterification reaction tank. It is preferable to control the variation in heat amount within an appropriate range.

That is, a slurry consisting of dicarboxylic acid and glycol is prepared in a slurry preparation tank, the slurry is continuously supplied to an esterification reaction tank, an esterification reaction is performed using the esterification reaction tank, and then the slurry is fed to a polymerization reaction tank. In a method for continuously producing polyester resin by continuously supplying and polymerizing, it is preferable to suppress the carboxyl end group concentration at the outlet of the esterification reaction tank to which the slurry is supplied to within ±10% of the set value. . It is preferably within ±9%, more preferably within ±8%, and even more preferably within ±6%. By setting it within this range, it is possible to suppress fluctuations in the carboxyl end group concentration of the oligomer at the outlet of the final esterification reaction tank to a preferable range, which can lead to stabilization of the subsequent polymerization reaction and the quality of the obtained polyester resin. This is preferable because it can be done. On the other hand, the lower limit is most preferably ±0% with no fluctuation, but from the point of view of cost performance, ±0.5% is preferable, and ±1.0% is more preferable. As a result, even if the control of the subsequent esterification reaction tank is at a conventionally known level of fluctuation, fluctuations in the carboxyl end group concentration of the polyester oligomer supplied to the polymerization process can be greatly suppressed.

Furthermore, in the above esterification reaction step, the concentration of carboxyl end groups and hydroxyl end groups of the polyester oligomer are measured online and fed back to the slurry temperature control system to improve control accuracy and stability. preferable.

Although the method for measuring the oligomer properties is not limited, it is preferable to use a near-infrared spectrophotometer. It is preferable to conduct the measurement continuously using a near-infrared spectrophotometer in a portion where the oligomer is flowing, such as a reaction vessel or piping. There is no particular limitation as long as it is a near-infrared spectrophotometer that can continuously measure online. For example, commercial products such as near-infrared online analyzers manufactured by NIRS Systems (Nireco), BRAN LUEBBE, and Yokogawa Electric Corporation may be used, or a systemized device may be manufactured for this purpose. You may respond.

Note that the detection cell of the near-infrared spectrophotometer must be installed in a high-temperature region, and a design to accommodate this is required. In addition, if installed between esterification reactors, it must be in a pressurized state, and if installed in the transfer line from the esterification reactor to the initial polymerization reactor, it must be constructed so that it can withstand both pressurization and depressurization. be. It is preferable to take appropriate measures depending on the installation location, etc.

The measurement cell of the near-infrared spectrophotometer may be installed at any location from the start of the esterification reaction to just before the start of the polymerization reaction. It may be set in the esterification reaction vessel or may be installed in the transfer line of each reaction vessel. It may be installed directly in each reaction vessel or transfer line, or it may be installed in a bypass line provided. When detecting the inside of a reaction vessel installed in the bypass line, it is preferable to provide a circulation line through which the reaction contents circulate in the target reaction vessel, and install the detection vessel in the circulation line. Since the installed measurement cell may require maintenance, it is preferably installed in a bypass line. In the present invention, as mentioned above, the concentration of carboxyl end groups of the oligomer at the outlet of the first esterification reaction tank is important, so for example, a bypass line is connected to the transfer line from the first esterification reaction tank to the second esterification reaction tank. It is preferable to install a detector on the bypass line for measurement. Furthermore, another detector may be installed in the transfer line from the final esterification reaction tank to the first polymerization reaction tank to measure the characteristic values of both oligomers to improve control accuracy. In the method of controlling the esterification reaction using a plurality of detectors, the control based on the measurement value measured by the detector installed in the transfer line at the outlet of the first esterification reaction tank is performed in the first esterification reaction tank. It is preferable to perform this by feeding back the temperature of the slurry supplied to the slurry. Control based on measured values detected at other detection locations is a control system that changes other esterification reactions, for example, by feeding back to the supply amount of glycol for adjusting the esterification reaction supplied to the second esterification reaction tank. Good too. The control system that can improve the accuracy the most may be appropriately selected and implemented.

The above oligomer properties can be measured by measuring only the carboxyl end group concentration, or by measuring both carboxyl end group concentration and hydroxyl end group concentration at the same time, or if measuring at multiple locations, measure at each location. You may change the content. For example, a control system using a detector installed in the transfer line at the outlet of the first esterification reaction tank controls the concentration of carboxyl end groups, and a control system using a detector installed in the transfer line at the exit of the final esterification reaction tank controls the concentration of carboxyl end groups. It is preferable to measure both the concentration and the hydroxyl end group concentration simultaneously and to control both end group concentrations so that they fall within a predetermined range. The measurement wavelength of near-infrared rays is not limited. It is preferable to use a model oligomer corresponding to the measurement location to investigate a wavelength with high sensitivity and little disturbance, and to set it appropriately. For example, it is preferred to use a wavelength of 1444 nm for carboxyl end group concentrations and 2030 nm for hydroxyl end group concentrations.

It is preferable that a calibration curve for both end group concentrations determined by the above method be created using the above model oligomer. In this case, it is preferable to use values measured by NMR method as the carboxyl end group concentration and hydroxyl end group concentration of the model oligomer.

The number and size of reactors in the polymerization step in the present invention, the manufacturing conditions for each step, etc. can be appropriately selected without limitation.

For example, in the case of a three-stage system of initial polymerization, middle stage polymerization, and late stage polymerization, the polymerization reaction conditions are as follows: The reaction temperature of the first stage polymerization is 250 to 290°C, preferably 260 to 280°C, and the pressure is 2.6°C. -65kPa, preferably 4-27kPa, the temperature of the final stage polymerization reaction is 265-300°C, preferably 265-290°C, and the pressure is 0.013-1.3kPa, preferably 0.065-0. It is 65kPa. When the polymerization reaction is carried out in three or more stages, the reaction conditions of the intermediate stage polymerization reaction are between the reaction conditions of the first stage and the final stage. Preferably, the degree of increase in intrinsic viscosity achieved in each of these polymerization reaction steps is smoothly distributed.

(Addition of polymerization catalyst for polyester resin)
In the present invention, the method and place of adding the aluminum compound solution and the phosphorus compound solution are not limited. It is preferable that the aluminum compound solution and the phosphorus compound solution are added at the same time. Adding at the same time includes a method in which each component is added individually to the same reaction vessel or to piping between the reaction containers, and a method in which the aluminum compound solution and the phosphorus compound solution are mixed in advance to form a single solution and then added. Examples of methods for making the solutions into one liquid include a method of mixing the respective solutions in a tank, and a method of merging the pipes for adding the catalyst in the middle and mixing them. In addition, when adding to a reaction container, it is preferable to increase stirring of the reaction container. When adding the catalyst solution to a pipe between reaction vessels, it is preferable to install an in-line mixer or the like so that the added catalyst solution can be quickly and uniformly mixed.

If an aluminum compound solution and a phosphorus compound solution are added separately, a large amount of foreign matter caused by the aluminum compound is likely to be generated, resulting in a lower heating crystallization temperature, a higher cooling crystallization temperature, and insufficient catalytic activity. You may not be able to obtain it. By adding an aluminum compound and a phosphorus compound at the same time, a complex of the aluminum compound and a phosphorus compound that brings about polymerization activity can be generated quickly and without waste, but if they are added separately, There is a possibility that the aluminum compound is insufficiently produced and that the aluminum compound that has not been able to form a complex with the phosphorus compound will precipitate as a foreign substance.
Further, the aluminum compound solution and the phosphorus compound solution are preferably added after the esterification reaction or transesterification reaction is completed. If it is added before the completion of the esterification reaction or transesterification reaction, the amount of aluminum-based foreign substances may increase.

(Solid phase polymerization method for polyester resin)
In the present invention, as a method for lowering the CT amount, it is preferable to additionally polymerize a polyester resin produced by a melt polymerization method by a solid phase polymerization method. Solid phase polymerization is carried out by pulverizing the polyester obtained by the melt polymerization method. Powder means chips, pellets, flakes, and powdered polyester, preferably chips or pellets, and usually has an average particle size of 2.0 to 5.5 mm, preferably 2.2 to 4.0 mm. It is desirable to have

The above-mentioned solid phase polymerization is carried out by heating the powdered polyester at a temperature below the melting point of the polyester under an inert gas flow or under reduced pressure. The solid phase polymerization step consists of at least one stage, the polymerization temperature is usually 190 to 235°C, preferably 195 to 230°C, and in the case of an inert gas flow method, the pressure is usually 0.98 MPa to 0.0013 MPa, preferably is carried out under conditions of 0.49 MPa to 0.013 MPa under the flow of an inert gas such as nitrogen, argon, carbon dioxide, etc. In the case of a reduced pressure method, the pressure is usually 13 to 39,000 Pa, preferably 13 to 13,300 Pa. It will be carried out below. The solid phase polymerization time is generally 1 to 50 hours, preferably 5 to 30 hours, and more preferably 10 to 25 hours, although the higher the temperature, the faster the desired physical properties are achieved. The solid phase polymerization step may be performed in multiple stages.

The powdery polyester supplied to the solid phase polymerization step may be pre-crystallized by heating to a temperature lower than the temperature at which the solid phase polymerization is performed, and then supplied to the solid phase polymerization step.

Such pre-crystallization step may be carried out by heating the granular polyester in a dry state to a temperature of usually 120 to 200°C, preferably 130 to 180°C for 1 minute to 4 hours, or by heating the granular polyester to a temperature of 1 minute to 4 hours. It may be carried out by heating to a temperature of usually 120 to 200° C. for 1 minute or more in a steam atmosphere, a steam-containing inert gas atmosphere, or a steam-containing air atmosphere.

The polyester melt-polymerized as described above is, for example, chipped and then transported through transportation piping to a storage silo or a solid phase polymerization process. If such chips are transported by a forced low-density transport method using air, for example, a large impact force is applied to the surface of the melt-polymerized polyester chips due to collision with the piping, resulting in fine and film-like A lot of things are generated. Such fine and film-like materials have the effect of promoting crystallization of polyester, and when present in large amounts, the transparency of the obtained molded product becomes extremely poor. Therefore, it is one of the preferred embodiments to add a step of removing such fines and film-like materials.

The method for removing the above-mentioned fines and film-like materials is not limited, but examples include a vibrating sieve step installed separately in the intermediate step between the solid phase polymerization step and a post-step step installed after the solid phase polymerization step; Examples include a treatment method using an airflow classification process using an airflow, a gravity classification process, and the like.

The polyester obtained by the production method of the present invention is more effective against mold stains caused by oligomers such as cyclic trimers adhering to the inner surface of the mold, the gas exhaust port of the mold, the exhaust pipe, etc. during molding. In order to prevent this, a contact treatment with water can be carried out after the solid state polymerization. The method is not limited, but examples include a method of immersing the chip in water and a method of sprinkling water on the chip in a shower. The treatment time is 5 minutes to 2 days, preferably 10 minutes to 1 day, more preferably 30 minutes to 10 hours, and the water temperature is 20 to 180°C, preferably 40 to 150°C, more preferably 50 to 150°C. The temperature is 120°C.

The solid-phase polymerization and the above-mentioned accompanying treatments in the present invention may be carried out either batchwise or continuously, but a continuous method is preferred from the viewpoint of uniform quality of the resulting polyester and economical efficiency.

In the present invention, the degree of polymerization of the polyester may be appropriately set according to the required characteristics of the intended use of the obtained polyester, but in general, polyester having an intrinsic viscosity of 0.3 to 0.65 dl/g by melt polymerization is used. It is preferable to increase the intrinsic viscosity of the polyester obtained by the melt polymerization to 0.60 to 1.20 dl/g by solid phase polymerization.

(Method for manufacturing polyester resin blow molded body)
Although the method for producing the polyester resin blow-molded article in the present invention is not limited, it is preferably carried out by the following method.

In blow molding of heat-resistant bottles, a bottomed precursor called a preform is generally created, this preform is blow-stretched in a mold, and then heat-set. For manufacturing the preform, methods such as compression molding and injection molding are used. Taking injection molding as an example, a preform can be obtained by heating and melting the material to 260 to 300° C. and injecting it into a preform mold. Typically, the preform is thick-walled and has a test tube-like shape with a gate at the bottom and a cap screw carved into the spout.

For heat-resistant bottles, the spout of the obtained preform is crystallized. Crystallization can prevent the spout from deforming even when filling with high-temperature contents. Crystallization of the spout is preferably carried out by heating to 130 to 200°C, more preferably 140 to 190°C. As a heating method, an infrared heater, hot air, induction heating, immersion in an oil bath, etc. can be used, and it is preferable to use an infrared heater from the viewpoint of productivity. Note that the spout may be heated and crystallized after blow molding.

The preform is heated, stretched in the bottle length direction (vertical direction), and blow molded in the circumferential direction to obtain a bottle. It is stretched in the length direction using a generally rod-shaped stretching rod, and in the circumferential direction a pressurized gas such as air or nitrogen is used. The pressurized gas is preferably 1 to 10 MPa. It is preferable to blow pressurized gas while inserting a stretching rod and stretch the material simultaneously in the length direction and the circumferential direction, but it is also possible to stretch it in the length direction and then in the circumferential direction. For heating, infrared heaters, hot air, induction heating, etc. are used. The heating temperature is usually 80 to 130°C, preferably 90 to 120°C.

The lower limit of the stretching ratio in the longitudinal direction of the bottle is preferably 1.5 times, more preferably 2 times. If it is less than the above, uneven stretching may occur. The upper limit of the stretching ratio in the length direction is preferably 6 times, more preferably 5 times, and even more preferably 4 times. If the above is exceeded, breakage etc. are likely to occur.

The lower limit of the stretching ratio in the circumferential direction of the bottle is preferably 2 times, more preferably 2.5 times. If it is less than the above, uneven stretching may occur. The upper limit of the stretching ratio in the circumferential direction is preferably 6 times, more preferably 5 times, and still more preferably 4 times. If the above is exceeded, breakage etc. are likely to occur.

When heat setting is performed in the same mold after blow molding, the lower limit of the mold temperature for blow molding is preferably 80°C, more preferably 120°C, still more preferably 130°C, and most preferably The temperature is 140°C. If it is less than the above, sufficient crystallization may not be promoted in the subsequent heat setting, resulting in insufficient heat resistance, or it may be necessary to take a long heat setting time, resulting in a decrease in productivity.

The upper limit of the mold temperature is preferably 200°C, more preferably 190°C, still more preferably 180°C, particularly preferably 170°C. As the mold temperature increases, mold contamination increases and the number of times that continuous molding can be performed may decrease.

The blow molded bottle is then heat set in a mold. The lower limit of the heat set time is preferably 0.5 seconds, more preferably 1 second, and still more preferably 1.5 seconds. If it is less than the above, sufficient crystallization may not be promoted and heat resistance may be insufficient. The upper limit of the heat set time is 15 seconds, preferably 10 seconds, and more preferably 5 seconds. Not only does a long heat setting time result in poor productivity, but in the case of a rotary blow molding machine, it is necessary to prepare a large number of molds, which may lead to poor economic efficiency when the equipment becomes large. Note that after heat setting in the mold, additional heat setting may be performed by further heating with infrared rays, hot air, induction heating, or the like.

It is also possible to perform blow molding in a mold at 5 to 50° C. and then heat set in a heated mold. The temperature of the heat set mold in this case is the same as the mold temperature in the above case.

Blow molding equipment may be equipped with one mold, but in the case of mass production, it is equipped with multiple molds, and these molds have a place where heated preforms are set in the mold, It is preferable to use a system in which the stretching location, heat setting location, and bottle ejection location are sequentially moved.

Although the cold parison method in which a cooled preform is reheated has been described above, a hot parison method in which blow molding is performed without completely cooling the preform is also possible.

The content of the bottle to be molded is preferably 200 mL to 6 L. Particularly preferred is one between 300 mL and 2 L. The shape of the bottle body can be any shape such as a circle, a square (including shapes with cut corners), and a hexagon.

EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples. The evaluation methods used in each example and comparative example are as follows.

[Evaluation method]
(1) Intrinsic viscosity (IV) of polyester resin
The polyester resin was dissolved in a 6/4 (weight ratio) mixed solvent of phenol/1,1,2,2-tetrachloroethane and measured at a temperature of 30°C.

(2) Quantification of the total amount of phosphorus elements bonded to the terminal hydroxyl group of polyester relative to the total amount of phosphorus elements present in the polyester resin (2-1) P-NMR spectrum measurement 420 mg of polyester resin was mixed with hexafluoroisopropanol + It was dissolved in 2.7 mL of heavy benzene (1+1) mixed solvent, 10 μL of 25% phosphoric acid solution in heavy acetone was added, and centrifugation was performed. Thereafter, 100 to 150 mg of trifluoroacetic acid was added to the supernatant, and immediately P-NMR measurement was performed. Note that the method for measuring the amount of polyester terminal group-bonded phosphorus compounds is not limited to the same method as above, and the above-mentioned (Formula 1) to (Formula 3) (hereinafter referred to as "three types of polyester terminal group-bonded phosphorus compounds") Any method that can confirm the peak corresponding to is sufficient.
Equipment: Fourier transform nuclear magnetic resonance apparatus (BRUKER, AVANCE500)
31P resonance frequency: 202.456MHz
Locking solvent: Heavy benzene Detection pulse flip angle: 65°
Data acquisition time: 1.5 seconds Delay time: 0.5 seconds Proton decoupling: Full decoupling Measurement temperature: 25-35℃
Accumulated number of times: about 20,000 to 30,000 times

(2-2) Quantification method In the spectrum obtained in (2-1) above, 6 peaks were observed at 27-38 ppm and 0-3 peaks at 50-55 ppm. The three peaks corresponding to the three types of polyester terminal group-bonded phosphorus compounds appear at 27 to 38 ppm. Compared to the other three peaks that do not correspond to the three group-bonded phosphorus compounds, there are three peaks with almost no shift change, and the chemical shift values are 28.8 ± 0.3 ppm for the first peak and 30.1 for the second peak. ±0.3ppm, and the third one was 30.5±0.3ppm. The shift difference between the first peak and the second peak is 1.3±0.1 ppm, and the shift difference between the second peak and the third peak is 0.4±0.1 ppm. The ratio of the integral values of these three peaks to the total of the integral values of the peaks corresponding to all phosphorus compounds was determined and shown as a, b, and c in Table 4. In addition, the total value of a to c above was taken as the amount of polyester end-bonded phosphorus element (the total amount of phosphorus element contained in the three types of polyester end group-bonded phosphorus compounds relative to the total amount of phosphorus element present in the polyester resin).

(3) Determination of aluminum element in polyester resin (dry decomposition method)
A polyester resin was weighed in a platinum crucible, carbonized in an electric stove, and then incinerated in a muffle furnace at 550° C. for 8 hours. After the incinerated sample was acid-treated with 6M hydrochloric acid, the volume was adjusted to 20 mL with 1.2M hydrochloric acid.
Metal concentration was determined by ICP luminescence measurement.
Equipment: CIROS-120 manufactured by SPECTRO
Plasma output: 1400W
Plasma gas: 13.0L/min
Auxiliary gas: 2.0L/min
Nebulizer: Crossflow nebulizer Chamber: Cyclone chamber Measurement wavelength: 167.078nm

(4) Determination of phosphorus element in polyester resin (molybdenum blue colorimetric method)
The polyester resin was subjected to wet decomposition with sulfuric acid, nitric acid, and perchloric acid, and then neutralized with aqueous ammonia. After adding ammonium molybdate and hydrazine sulfate to the prepared solution, the absorbance at a wavelength of 830 nm was measured using an ultraviolet-visible spectrophotometer (manufactured by Shimadzu Corporation, UV-1700).

(5) Amount of aluminum-based foreign matter Pour 30 g of polyester resin and 250 mL of parachlorophenol/tetrachloroethane (3/1: weight ratio) mixed solution into a 500 mL Erlenmeyer flask equipped with a stirrer, and use a hot stirrer to The mixture was heated and dissolved at 105°C for 1.5 hours. The solution was filtered to remove foreign substances using a polytetrafluoroethylene membrane filter (PTFE membrane filter manufactured by Advantec, product name: T100A047A) having a diameter of 47 mm and a pore size of 1.0 μm. The effective filtration diameter was 37.5 mm. After the filtration was completed, the filter was washed with 50 mL of chloroform, and then the filter was dried.
The amount of aluminum element on the filtration surface of the membrane filter was determined using a scanning fluorescent X-ray analyzer (manufactured by RIGAKU, ZSX100e, Rh line bulb 4.0 kW). Quantification was performed on a 30 mm diameter portion at the center of the membrane filter. The calibration curve for the fluorescent X-ray analysis method was determined using a polyethylene terephthalate resin with a known aluminum element content, and the apparent aluminum element content was expressed in ppm. The measurement was carried out by measuring the Al-Kα ray intensity at an X-ray output of 50 kV-70 mA, using pentaerythritol as a spectroscopic crystal, a PC (proportional counter) as a detector, and a PHA (wave height analyzer) of 100-300. . The amount of aluminum element in the PET resin for the calibration curve was determined by high frequency inductively coupled plasma emission spectrometry.

(6) Quantification of CT and ΔCT A solid-phase polymerized polyester resin or a polyester resin blow-molded body molded by the method described below was freeze-pulverized or cut into pieces, and 100 mg of the sample was precisely weighed. This was dissolved in 3 mL of a hexafluoroisopropanol/chloroform mixture (volume ratio = 2/3), and further diluted with 20 mL of chloroform. 10 mL of methanol was added to this to precipitate the polymer, which was then filtered. The filtrate was evaporated to dryness and made up to volume with 10 mL of dimethylformamide. The cyclic trimer was then quantified using the high performance liquid chromatography method described below.
Note that the CT amount indicates the amount of cyclic trimer in the solid phase polymerized polyester resin. Further, the ΔCT amount is the value obtained by subtracting the amount of cyclic trimer in the polyester resin subjected to solid phase polymerization from the amount of cyclic trimer in the blow molded product made of polyester resin. Furthermore, the total CT amount (=CT amount+ΔCT amount) is the amount of cyclic trimer in the polyester resin blow molded article.
Equipment: L-7000 (manufactured by Hitachi, Ltd.)
Column: μ-Bondasphere C18 5 μ 100 angstrom 3.9 mm x 15 cm (manufactured by Waters)
Solvent: Eluent A: 2% acetic acid/water (v/v)
Eluent B: Acetonitrile Gradient B%: 10 → 100% (0 → 55 minutes)
Flow rate: 0.8ml/min Temperature: 30℃
Detector: UV-259nm

(7) Preparation of aluminum compound A 20 g/L aqueous solution of basic aluminum acetate was charged with an equal amount (volume ratio) of ethylene glycol, and after stirring at room temperature for several hours, under reduced pressure (3 kPa), Water was distilled off from the system while stirring at 50 to 90° C. for several hours to prepare an ethylene glycol solution containing 20 g/L of an aluminum compound.

(8) Preparation of phosphorus compound As a phosphorus compound, Irganox 1222 (manufactured by BFA Co., Ltd.) was charged into a preparation tank together with ethylene glycol, and heated at a liquid temperature of 175°C for 2 and a half hours with stirring under nitrogen substitution, so that 50 g/ An ethylene glycol solution containing L was prepared. The mole fraction of the phosphorus compound represented by (Formula 4) in the obtained solution was 40%, and the mole fraction of the compound whose structure had changed from (Formula 4) was 60%.

Examples 1 and 2, Comparative Examples 1 and 2
(melt polymerization method)
It consisted of three continuous esterification reactors and three polycondensation reactors, and an in-line mixer with a high-speed stirrer was installed in the transfer line from the third esterification reactor to the first polycondensation reactor. A slurry prepared by mixing 0.75 parts by mass of ethylene glycol with 1 part by mass of high-purity terephthalic acid was continuously supplied to a continuous polyester manufacturing apparatus, and the temperature, pressure, and residence time listed in Table 3 were maintained. A lower condensate was obtained by reacting according to the following procedure. The lower-order condensation product was continuously transferred to a continuous polycondensation apparatus consisting of three reactors, and polycondensation was performed according to the temperature, pressure, and residence time listed in Table 3, and the IV was 0.554 dl/g. of PET was obtained. The polyester resin was extruded into strands, cooled in water, and then cut into chips with an average particle weight of 23.5 mg.
Note that the polyester resin was produced under the conditions listed in Table 3. In addition, in order to eliminate the influence of the previous batch and ensure a high-quality product, the polyester resin was sampled more than 30 hours after the start of operation or the change of conditions.
From the in-line mixer, the ethylene glycol solution containing 20 g/L of the aluminum compound prepared by the above method and the ethylene glycol solution containing 50 g/L of the phosphorus compound prepared by the above method were added after the completion of polymerization. The amount was added so that the residual amount was as shown in Table 4 based on the mass of the polyester resin obtained.

(Solid phase polymerization method)
Next, the obtained chips were transported to a continuous solid phase polymerization apparatus. The mixture was crystallized at about 155° C. under a nitrogen atmosphere, and after being preheated to about 200° C. under a nitrogen atmosphere, it was sent to a continuous solid phase polymerization reactor and subjected to solid phase polymerization at about 207° C. under a nitrogen atmosphere. Subsequently, fines and film-like materials were removed by a vibrating sieving process and an air classification process to obtain a polyester resin having an IV of 0.735 dl/g.

(Method for manufacturing polyester resin blow molded body)
The polyester resin was dried in a vacuum dryer to a moisture content of 100 ppm or less, and then molded using a Meiki Seisakusho 150C-DM injection molding machine and a preform mold (mold temperature 5°C). Molded the renovation. The plasticizing conditions using the M-150C-DM injection molding machine are: feed screw rotation speed = 70%, screw rotation speed = 120 rpm, back pressure 0.5 MPa, cylinder temperature from directly below the hopper to 45°C, 250°C, and including the nozzle. The cylinder temperature thereafter was set at 290°C. In addition, the injection pressure and holding pressure were adjusted so that the weight of the molded product was 28.4±0.2 g.
Next, the spout of the preform was heated and crystallized using an NC-01 spout crystallizer manufactured by Frontier Co., Ltd. Furthermore, using an SBO Lab N° 1045 Type 1 Lab blow molding machine manufactured by Sidell, the mold was molded vertically at 750 bph in a molding cycle of 30 seconds while blowing air at a pressure of 36 bar in the mold set at 160°C. The preform was biaxially stretched and blown at a magnification of 2.5 times in the circumferential direction and 3.8 times in the circumferential direction.

Table 4 shows the conditions of the final melt polymerization tank (third polymerization tank) of the polyester resins obtained in Examples 1 and 2 and Comparative Examples 1 and 2 and the characteristic values of the polyester resin blow molded articles.

In Table 4, the CT amount is the measured value of the cyclic trimer contained in the solid phase polymerized product of polyester resin, and the total CT amount (=CT amount + ΔCT amount) is the measured value of the cyclic trimer contained in the polyester resin blow molded product. It is a measured value. Further, the amount of aluminum-based foreign matter and the amount of end-capped phosphorus compound are measured values of the polyester resin obtained by the melt polymerization method. The amount of aluminum-based foreign substances and the amount of end-capped phosphorus compounds do not change substantially during solid phase polymerization treatment and blow molding evaluation, so the measured values in Table 4 are also the same for solid phase polymerized products of polyester resin and blow molded products made of polyester resin. It was considered as a degree. The amount of aluminum-based foreign substances and end-capped phosphorus compounds do not change during the solid-phase polymerization and blow molding processes because the temperature is low in the solid-phase polymerization process, and the residence time in the blow molding process is extremely short. I believe.

The polyester resins and polyester resin blow molded articles of Examples 1 and 2 have a lower CT amount and total CT amount (CT amount + ΔCT amount), and are of higher quality than the polyester resins and polyester resin blow molded articles of Comparative Examples 1 and 2. It is.

Using the results of the Examples and Comparative Examples in Table 4, the relationship between T×RT×(P/Al) and CT and ΔCT is shown in Figure 1. Figure 2 shows the relationship between T x RT Figure 4 shows the relationship between the amount of end-capped phosphorus compound and the solid phase polymerization rate.

From these figures, it is clear that the scope of the claims of the present invention is critical. Furthermore, it is clear that the CT amount and the ΔCT amount are antinomic events.

The polyester resin of the present invention relates to a polyester resin obtained using a polymerization catalyst consisting of an aluminum compound and a phosphorus compound in which the main metal component of the catalyst is a metal component other than antimony element, germanium element, and titanium element. . In addition to having various stability characteristics such as color tone and heat resistance that are characteristic of polyester resins obtained using the polymerization catalyst, the production of aluminum-based foreign matter is suppressed and the resin has high transparency. In addition, since a part of the terminal hydroxyl group of the polyester resin is blocked by a phosphorus compound, the generation of CT and ΔCT in the manufacturing process of the polyester resin and the molding process of blow molding the polyester resin is suppressed, and the molding die The effect of suppressing contamination is exhibited, and furthermore, the solid phase polymerization rate can be improved. Therefore, it will greatly contribute to industry.

Claims (7)

A polyester resin containing a catalytic amount of an aluminum compound-derived component and a phosphorus compound-derived component, wherein the polyester resin contains 85 mol% or more of ethylene terephthalate structural units, and the hydroxyl of the polyester is based on the total amount of phosphorus present in the polyester resin. The total amount of phosphorus elements present bonded to the group terminals is 42 to 60 mol%,
The content of aluminum element is 13 to 25 ppm,
A polyester resin characterized in that the molar ratio of phosphorus element to aluminum element (P/Al) is 1.5 to 3.5 . The polyester resin according to claim 1, wherein the amount of cyclic trimer is 3300 ppm or less. The polyester resin according to claim 1 or 2, wherein the polyester resin has a moisture content of 100 ppm or less and an amount of cyclic trimer generated when melt-molded at a cylinder temperature of 290° C. of an injection molding machine is 650 ppm or less. The polyester resin according to any one of claims 1 to 3, wherein the structure of the phosphorus compound bonded to the terminal hydroxyl group of the polyester resin is at least one of the following (Formula 1) to (Formula 3).

The polyester resin according to any one of claims 1 to 4, wherein the content of elemental phosphorus is 25 to 60 ppm. A polyester resin blow molded article molded using the polyester resin according to any one of claims 1 to 5 . The polyester resin blow molded article according to claim 6 , wherein the content of the cyclic trimer is 3600 ppm or less.

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