KR0134657B1 - Method for manufacturing copolyester - Google Patents

Abstract

The present invention uses terephthalic acid and ethylene glycol as the main raw materials, and during the polycondensation reaction, 2-10 equivalent% of 1,4-cyclohexane dimethanol and / or its functional derivatives are added based on ethylene glycol, and the following general formula (6 ) And the crosslinking agent represented by (7) and the terminal group blocking agent represented by the general formula (8) in the solid state or in the form of a slurry with ethylene glycol in the preparation of polyethylene terephthalate copolyester decomposition reaction during the ester reaction Phosphorus compound (D) using an ammonium compound (A) as an excipient, glycol soluble antimony compound (B) and tin compound (C) as a polymerization catalyst, and having an amine bond represented by the general formula (1) as a stabilizer (D) ), Cobalt compound (E), which is a color improving agent, is added to satisfy the formulas (2), (3), (4) and (5), and is excellent in color and transparency, and has high melt strength, gel free, High shear rate dependence Having the relates to a process for preparing a copolymer of a suitable polyester for extrusion blow-molding.

80 〈A 〈400 (2)

210 〈B + C + E 〈300 (B〉 100) (3)

0.3 1.8 (4)

1 <C / E <1.5 (5)

(Wherein R ¹ , R ² , R ³ and R ⁴ are hydrogen atoms or alkyl or aryl groups having 1 to 10 carbon atoms, R ⁵ is an alkylene group or benzing having 1 to 10 carbon atoms, and A, B, C , D and E indicate the content (ppm) of each compound in the polymer.)

R ¹ (OH) _k (6)

R ² ---- (CH ₂ OH) ₁ (7)

(R ¹ = saturated aliphatic hydrocarbon radical having 3 to 6 carbon atoms)

K = 3 to 6

R ² = saturated aliphatic hydrocarbon radical having 1 to 6 carbon atoms

I = 3 to 6)

(X: hydrogen, aliphatic radical, alkoxy group, aryloxy group, halogen)

Description

Process for producing polyester copolymer

The present invention relates to a method for producing a polyester copolymer suitable for extrusion hollow molding having excellent color tone and transparency, high melt strength, gel-free, and high shear rate dependence, and more specifically, terephthalic acid and ethylene Using glycol as a main raw material, 2-10 equivalent% of 1,4-cyclohexanedimethanol and / or functional derivatives thereof selected from linear and cyclic aliphatic glycols are added at the time of condensation polymerization reaction. The crosslinking agent represented by the general formulas (6) and (7) and the terminal group blocking agent represented by the general formula (8) are added in the solid state or in the slurry state with ethylene glycol, and the ammonium compound ( ㅁ), a glycol soluble antimony compound (B) and a tin compound (C) as a polymerization catalyst, and a phosphate compound having an amine bond represented by the general formula (1) as a stabilizer. It relates to a method for producing a polyester by adding water (D) and a cobalt compound (E), which is a color tone improving agent, to satisfy the formulas (2), (3), (4) and (5).

80 〈A 〈400 (2)

210 〈B + C + E 〈300 (B〉 100) (3)

0.3 〈1.8 (4)

1 <C / E <1.5 (5)

(Wherein R ¹ , R ² , R ³ and R ⁴ are hydrogen atoms or alkyl or aryl groups having 1 to 10 carbon atoms, R ⁵ is an alkylene group or benzing having 1 to 10 carbon atoms, and A, B, C , D and E indicate the content (ppm) of each compound in the polymer.)

R ¹ (OH) ^k (6)

R ² ---- (CH ₂ OH) ₁ (7)

(R ¹ = saturated aliphatic hydrocarbon radical having 3 to 6 carbon atoms)

K = 3 to 6

R ² = saturated aliphatic hydrocarbon radical having 1 to 6 carbon atoms

I = 3 to 6)

(X: hydrogen, aliphatic radical, alkoxy group, aryloxy group, halogen)

In general, polyester has excellent mechanical and chemical properties, and thus, there are various uses such as films, blow moldings, etc. in addition to clothes, sheets, fishing nets, tents and tire cords. In particular, thermoplastic polyesters based on ethylene glycol terephthalate units have been used as cosmetics, pharmaceuticals, foods, and packaging materials in the form of films, sheets, and containers.

Modified polyethylene terephthalates for use in the injection molding process are described in US Pat. Nos. 3673139 and 3692744. These patents relate to the introduction or combination of crosslinking agents and crystallization inhibitors in polyethylene terephthalates to give injection moldable adjustments.

Attempts have been made to introduce various modified polyesters, including polyethylene terephthalate and the like, in the area different from extrusion of containers and bottles in the past by introducing crosslinkers or end group blockers, or both, US Pat. Nos. 2606261, 2936296, Nos. 2951827, 3033824, 3039979, 3055867, 3223666, 3546180 and the like.

However, these modified polyesters have the drawback that the overall haze value is lowered, as well as a poor color tone that includes yellow, which is a very important consideration in the manufacture of bottles and containers.

In particular, when polyethylene terephthalate homopolyester is used to introduce only a crosslinking agent and a terminal group blocking agent, it is observed to have a partially opaque part by extrusion molding by a general technique. In particular, when making such containers or bottles by extrusion molding such modified polyester, the thick neck of the bottle becomes opaque. There should be no opacity due to aesthetic demands in various applications such as cosmetics, pharmaceuticals and food industry. In general, a high processing temperature should be applied to increase transparency, and problems such as yellowing and generation of side reactions (acetaldehyde, etc.) in the physical properties of the final molding are aroused. Higher processing temperatures are also the most important reason for higher molding costs.

Polyester copolymers using isophthalic acid or functional derivatives thereof known as a general method have a lower physical properties such as mechanical strength compared to homo polyesters (PET), making it difficult to apply to various applications. Therefore, studies on modified polyester having improved physical properties using 1,4-cyclohexane dimethanol have been conducted. For example, U.S. Pat.Nos. 3502620, 4219628, 4287325, 4426512, 4468510, 4560741 and the like are well shown.

Among them, the copolyester composition in which 1,4-cyclohexane dimethanol is added in an amount of 5 to 40 mol% based on the total amount of glycol is known to have easy physical properties for forming a container, a sheet, and a film.

Therefore, in this study, aliphatic glycol was added during the polymerization to prepare a polyester copolymer.

The use of such aliphatic glycols can increase the mechanical strength of the polymer, give rise to melt strength, give the proper formability, and give a polymer with a lower melting point. Particularly, solid phase polymerization can be carried out at lower temperatures. have. In addition, the crystallization rate and the crystallization temperature are low, which facilitates the quenching operation performed to remove the opacity generated in the thick tuck portion of the molded article or the like during the extrusion molding operation. However, when an excessive amount of aliphatic glycol structural unit is used, it has a low secondary transition temperature and tends to stick to each other during solid phase polymerization, thereby forming an amorphous polymer as a whole.

Accordingly, an object of the present invention is to introduce a combination of a crosslinking agent and a terminal group blocking agent, which is excellent in color tone and transparency, has a low crystallization rate, and has a high melt strength, gel-free, and high transfer rate dependency, thereby making it suitable for extrusion molding. It is to provide a method for preparing an ester.

In order to achieve the above object as well as another easily expressed object in the present invention in the production of polyester using terephthalic acid and ethylene glycol, 1,4-cyclo selected from linear and cyclic aliphatic glycol during the polycondensation reaction It is characterized by using hexanedimethanol and / or functional derivatives thereof, adding a crosslinking agent and a terminal group blocking agent, and adding various additives.

The present invention is described in more detail as follows.

In the present invention, after transferring the bis glycol ester or oligomer of terephthalic acid or its lower alkyl ester derivative and terephthalic acid obtained from ethylene glycol to a polycondensation reactor, 1,4-cyclohexane dimethanol and / or its functional derivatives are based on ethylene glycol. 2-10 equivalent%, and the crosslinking agent [Formulas (6) and (7)] and the terminal blocker [Formula (8)] were added in the solid state or in the form of a slurry with ethylene glycol to carry out the condensation polymerization. An ammonium compound (A) as a decomposition inhibitor, a glycol soluble antimony compound (B) and a tin compound (C) as a polymerization catalyst, and a phosphorus compound (D) having an amine bond represented by formula (1) as a stabilizer, Cobalt compound (E) is added as a color tone improver, but each formula (2), (3), (4) and (5) is added to satisfy the following procedure, and a prepolymer is prepared in a conventional manner to the desired degree of polymerization. Solid-state polymerization The manufacture of polyester.

80 〈A 〈400 (2)

210 〈B + C + E 〈300 (B〉 100) (3)

0.3 〈1.8 (4)

1 <C / E <1.5 (5)

(Wherein R ¹ , R ² , R ³ and R ⁴ are hydrogen atoms or alkyl or aryl groups having 1 to 10 carbon atoms, R ⁵ is an alkylene group or benzing having 1 to 10 carbon atoms, and A, B, C , D and E indicate the content (ppm) of each compound in the polymer.)

R ¹ (OH) _k (6)

R ² ---- (CH ₂ OH) ₁ (7)

(R ¹ = saturated aliphatic hydrocarbon radical having 3 to 6 carbon atoms)

K = 3 to 6

R ² = saturated aliphatic hydrocarbon radical having 1 to 6 carbon atoms

I = 3 to 6)

(X: hydrogen, aliphatic radical, alkoxy group, aryloxy group, halogen)

The linear and cyclic aliphatic glycols used in the polycondensation reaction may be neopentyl glycol, 1,6-hexanediol, 1,4-cyclohexane dimethanol, diethylene glycol, triethylene glycol, or the like. .

1,4-cyclohexane dimethanol or functional derivatives thereof are substituted in the ethylene glycol moiety used to make polyethylene terephthalate low molecular weight, and from 2 to 10 based on the amount of ethylene glycol used to make a totally transparent extruded blow molded article. It is about equivalent%. Therefore, the weight ratio of ethylene glycol unit and 1,4-cyclohexane dimethanol unit in the prepared copolymer is 90:10 to 98: 2. When 1,4-cyclohexane dimethanol or functional derivatives thereof are used in an amount of 2 equivalents or less than ethylene glycol, the synergistic effect of melt viscosity is insignificant, and molding processability cannot be expected to be increased. It has ionicity and tends to stick to each other during solid state polymerization, thus forming an amorphous polymer as a whole.In particular, after completion of the high polymerization, the melt viscosity increases, which may cause a problem in the screw due to high shear stress during molding. The gas barrier property is poor, and it is subject to usage restrictions.

As the crosslinking agent used in the present invention, one or two or more mixtures selected from the compounds represented by the general formulas (6) and (7) may be added in an amount of 0.02 to 1.4 mol%, preferably 0.05 to 1.0 mol%, based on terephthalic acid. It is good. If the amount is less than 0.02 mol%, the melt viscosity does not increase sufficiently, and if it exceeds 1.4 mol%, the physical properties of the composition are deteriorated.

When the crosslinking agent is present alone without using the end group blocking agent, the degree of polymerization in the solid phase polymerization reaction exceeds the critical gel point. (P.J.FLORY, PLINCIPELS OF POLYMER CHEMISRY P350, 1953) Thus, the gel forms a totally amorphous polymer.

Therefore, the terminal group blocking agent is used in 0.50 to 5 equivalent% based on the crosslinking agent used. The terminal group blocking agent suitable for the present invention is stearic acid (STEARIC ACID) or general formula (8) having a boiling point of 200 ° C. or higher, preferably 240 ° C. or higher, and stable enough not to cause decarboxylation even at 305 ° C. or higher. It is used one or a mixture of compounds represented by.

(X: hydrogen, aliphatic radicals, alkoxy groups, aFLFoxy groups, halogens)

Catalysts and stabilizers are usually used for the ester reaction and the polycondensation reaction. In the present invention, the softening point was increased by using an ammonium compound during the ester reaction. That is, 50 to 400 ppm of tetraethyl ammonium hydroxide is added at room temperature. When the amount is less than 50pm, the softening point is lowered, and when it is more than 400pm, the reaction rate is slowed.

Phosphoryl dimethyl ethanol diamine, 2-dimetalaminophenol diphenyl phosphate, 2-diethylaminoethanol dimethyl phosphate, 2-ethylpropylaminophenol dihydro as phosphorus compound (D) having an amine bond as a stabilizer in the condensation polymerization reaction Gen phosphate, 2-dibutylaminophenol dihydrogen phosphate and the like can be used.

The amount used is determined by the tin compound and the cobalt compound as shown in Equation (4). If the amount is 0.3 or less in Eq. (4), the transparency is lowered and the reactivity is deteriorated. When the amount is 1.6 or more, the polymer becomes yellow. The cobalt compound prevents the polymer from becoming yellow due to the tin compound, but since its transparency deteriorates when its amount is increased, the cobalt compound is used as shown in Equation (5). If it is yellowish.

Patents that use glycol-soluble antimony compounds and tin compounds as a polymerization catalyst in the manufacture of polyesters generally involve ester reactions to shorten the reaction of polyesters (Japanese Patent Application No. 55-5530). Since the color tone deteriorates, in the present invention, a polymer having improved physical properties and satisfactory transparency can be prepared by using a phosphorus compound (D) having an amine bond as a stabilizer and adding a large amount of cobalt compound as a color tone improver.

Examples of the antimony compound used in the present invention include antimony acetate, antimony tritrate, antimony trichloride, antimony trifluoride, antimony trioxide, and the like, and the tin compound includes monobutyl tin oxide, dibutyl tin oxide, and the like.

When soluble antimony compound and tin compound are used as a polymerization catalyst, dilute the concentration to 2.5% and 1.0% or less, respectively, and maintain the temperature of the input tank at 150 ℃ or higher, so that the reaction compound in the reactant may be evenly distributed. I could see that. The amount of catalyst used is about 100-250ppm. If the catalyst is less than 100ppm, the degree of polymerization is difficult to increase and the color tone is poor, which requires an excessive amount of cobalt compound to be injected. In addition, when the content exceeds 250ppm, the addition of a stabilizer is required due to the decrease in transparency and color tone, such as when the antimony compound is added alone, which has disadvantages such as deterioration of transparency and a long reaction time.

In carrying out the method of the present invention, the antimony compound of the tin compound is added at a temperature of 150 ° C. or higher, but the cobalt compound should be added to the same input bath after the antimony compound and the tin compound are dissolved.

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples.

Melting strength (MS)

MS = T ₁ / T ₂

(T ₁ : time required to extrude the first 3 inches out of total 6 inch length strands, T ₂ : time to extrude the second 3 inches)

Melt strength is measured by extruding it 6 inches with a melt index meter (MELT INDEXER) at a temperature high enough to keep the polymer molten (285 ° C). In order to apply to extrusion blow molding, it should have a value of 1 to 2.0. Ideally a value of 1.0 means that it is extruded at the same rate. The ideal polyester for extrusion molding is MS = 1.2 or less at 285 ° C.

Intrinsic Viscosity (IV)

IV = 1 nNr / c

(Nr: Relative viscosity at the same temperature, which is the viscosity of dilution solution divided by the viscosity of the applied solvent. C: concentration of solution g / 100ml)

IV is measured as 0.2 parts by weight solids of a 1,1,2,2-tetrachloroethane / phenol (4/6 parts by weight) solution. In the case of the prepolymer, it is measured by dissolving at 120 ° C. with an ortho chlorophenol solution.

Example 1

Tetraphthalic acid and ethylene glycol were added in a molar ratio of 1 / 1.2, respectively, and 0.01% by weight of tetraethylammonium hydroxide was added to the ester reaction tube and reacted for about 4 hours under a pressurized nitrogen atmosphere of 2 Kg / cm &lt; 2 &gt;. The reaction product is transferred to the condensation polymerization tube, and 1,4-cyclohexane dimethanol is added, but the amount of ethylene glycol and 1,4-cyclohexane dimethanol is added in an equivalence ratio of 95: 5.

At the same time, 0.33 parts by weight of trimethylolpropane as a crosslinking agent and 1.8 parts by weight of benzoic acid as a terminal group blocking agent are prepared in the form of a slurry with ethylene glycol and added in small amounts.

0.02 weight% of phosphoryl dimethyl ethanolamine is added after completion | finish of these raw materials. After stirring for 5 minutes at atmospheric pressure, the polymerization catalyst of the antimony compound and the tin compound is dissolved in 2.5% and 1% in advance in a dissolution tank and then added. The amount of catalyst containing the cobalt acetate compound was added to 0.012% by weight of antimony trioxide, 0.01% by weight of monobutyl tin oxide, and 0.008% by weight of cobalt acetate compound to continue the reaction (expressed in% by weight in the final polymer). Amount is converted value).

At this time, the pressure of the condensation polymerization tube is 1 mmHg or less and condensation polymerization for 3 hours 30 minutes at a temperature of 285 ~ 310 ℃ to obtain a prepolymer. The intrinsic viscosity of the obtained prepolymer is very transparent at the time of melting to 0.61 level L value 55.0, b value 0.7 and haze 0.50.

Intrinsic Viscosity (IV) is a value measured by a Wevelrod viscometer at 25 ° C using ortho chlorophenol as a solvent for prepolymers and 1,1,2,2-tetrachloroethane / It measured using phenol (4/6 weight part) as a solvent. The color tone of the polymer was obtained by using a color difference meter at room temperature for the finished polyethylene terephthalate polyester copolymer in each step of polymerizing the propolymer and the final polymer. The hue L value indicates lightness (the higher the value is good), and the b value indicates the color of yellow and blue (the lower the value, the better). In addition, the characteristics of the polymer are represented by solution haze, which was dissolved in a tetrachloroethane / phenol (4/6 parts by weight) solution at 120 ° C. and measured at room temperature with a haze meter (the lower the value, the better).

The prepolymer is subsequently subjected to a solid phase polymerization process to make a high melt strength, gel free, crosslinkable polyethylene terephthalate polyester copolymer suitable for extrusion molding. The prepolymer is slowly heated and dried at a temperature higher than the secondary transition temperature (Tg) (Tg = 70 to 80 ° C.), preferably at about 120 ° C. for 1 hour until the chips crystallize.

The dried chips were reacted in a conical solid-state polymerization vacuum dryer at 215 ° C. for 24 hours under 0.2 Torr. The intrinsic viscosity of the final polymer thus obtained was 1.05. It also had a very high shear rate dependence at a temperature of 275 ° C., and measured as 180000 poise at zero shear rate and 8000 poise at 10 ³ / sec. In fact, the melt strength value was measured to be 1.1.

In the extrusion blow molding process, the final polymer is passed through a hopper dryer to the end of the die in a screw-type extrusion. The screw array temperature ranges from 225 ° C to 285 ° C. The shear rate in the extruder is 1000 / sec.

The degree of transparency of the trunk portion of the final molded product was measured under normal temperature conditions using a haze meter as it was cut out from the center of the trunk (as the lower the value, the better).

Example 2 and Comparative Examples 1-4

As shown in Table 1, except that the composition or composition ratio of the raw material to be added was changed in the same manner as in Example 1, and the physical properties are shown in Table 1 to evaluate.

As shown in Table 1, it can be seen that the difference in melt strength and shear rate dependence by the crosslinking agent and the end group blocking agent selected from the composition based on terephthalic acid, ethylene glycol and 1,4-cyclohexanedimethanol is apparent. At the same time, it can be seen that the phosphorus compound having an amine bond, in particular, the difference in color tone and transparency due to the addition of phosphoryldimethylethanolamine.

a: Examples 1-2 and Comparative Examples 1, 3, and 4 were phosphoryl dimethylethanolamine. In Comparative Example 2, phosphoric acid was used.

b: It becomes impossible to measure because an excess gel exists in a polymer.

c: When molding, cosmetic melts are present, which makes it impossible to form proforms.

d: not measurable

TMP: trimethylolpropane

BA: benzoic acid

PETOL: Pentaerythritol

STA: stearic acid

CHDM: 1,4-cyclohexane dimethanol

IV-1: Intrinsic viscosity after liquid polymerization

IV-2: Intrinsic viscosity after solid state polymerization

Claims (4)

1,4-cyclohexane dimethanol and / or its functional derivative, crosslinked product and terminal group blocking agent are added in the polycondensation reaction step when preparing polyester mainly composed of terephthalic acid and ethylene glycol and decomposed during ester reaction. Ammonium compound (A) as a reaction agent, glycol soluble antimony compound (B) and tin compound (C) as a polymerization catalyst, phosphorus compound (D) having an amine bond represented by the general formula (1) as a stabilizer, A cobalt compound (E) is added to satisfy the following formulas (2), (3), (4) and (5): A method for producing a polyester copolymer. 80 〈A 〈400 (2) 210 〈B + C + E 〈300 (B〉 100) (3) 0.3 〈1.8 (4) 1 <C / E <1.5 (5) (Wherein R ¹ , R ² , R ³ and R ⁴ are hydrogen atoms or alkyl or aryl groups having 1 to 10 carbon atoms, R ⁵ is an alkylene group or benzing having 1 to 10 carbon atoms, and A, B, C , D and E indicate the content (ppm) of each compound in the polymer.) The method according to claim 1, wherein the amount of 1,4-cyclohexane dimethanol and / or functional derivatives thereof is 2 to 10 equivalent% based on the ethylene glycol used. The method for producing a polyester copolymer according to claim 1, wherein the crosslinking agent is at least one selected from the compounds represented by the following formulas (6) and (7) and uses 0.02 to 1.4 mol% based on terephthalic acid. R ¹ (OH) _k (6) R ² ---- (CH ₂ OH) ₁ (7) (R ¹ = saturated aliphatic hydrocarbon radical having 3 to 6 carbon atoms) K = 3 to 6 R ² = saturated aliphatic hydrocarbon radical having 1 to 6 carbon atoms I = 3 to 6) The method for producing a polyester copolymer according to claim 1, wherein the terminal group blocking material is at least one selected from the compounds represented by the following formula (8), and 0.5 to 5 equivalents are added to the intercalation equivalents of the crosslinking agent. . (X: hydrogen, aliphatic radical, alkoxy group, aryloxy group, halogen)