JPH10279672A - Production of polyester resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyester resin having flowability suited for extrusion blow molding by adding a specified amount of a hydrolyzable-functional-group- containing polymer to a polyester precondensate comprising an acid component containing an aromatic dicarboxylic acid and a glycol component containing an aliphatic dialcohol and subjecting the mixture to a polycondensation reaction. SOLUTION: 0.1-30 pts.wt. hydrolyzable-functional-group-containing polymer having a molecular weight of 50,000 or below is added to 100 pts.wt. polyester precondensate comprising an acid component containing at least 80 mol% aromatic dicarboxylic acid and/or an esterifiable derivative thereof and a glycol component containing an aliphatic dialcohol at least 50% of which is ethylene glycol, and the mixture is subjected to a polycondensation reaction to produce a polyester resin. The hydrolyzable-functional-group-containing polymer is desirably a polymer obtained by the vinyl polymerization of 5-90 wt.% hydrolyzable- functional-group-containing monomer and a hydrolyzable-functional-group-free monomer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a polyester resin having improved fluidity, and more particularly to a method for industrially efficiently producing a resin having fluidity suitable for extrusion blow molding.

[0002]

2. Description of the Related Art Extrusion blow molding is characterized by a low-pressure molding method capable of forming a hollow structure. This method has an economical advantage that the injection molding step can be omitted as compared with the stretch blow molding in which the cold parison is injection molded once.
It is often used in the manufacture of containers.

However, in injection molding, a molten resin is directly injected into a mold at high speed and high pressure. On the other hand, in extrusion blow molding, it is necessary to discharge the molten resin into the outside air at a low speed. There is a problem that the thickness unevenness becomes remarkable when trying to obtain a large molded product from a resin having a low melt viscosity.

On the other hand, polyester resins represented by polyethylene terephthalate and the like are excellent in mechanical properties, gas barrier properties and chemical resistance, and are used for beverage bottles and cosmetic containers, but have low melting points obtained by ordinary melt polymerization. In the case of polyester having a viscosity, drawdown during extrusion blow molding is liable to occur, so that there is a restriction that a large container having a volume of, for example, about 1 liter cannot be extrusion blow molded. Attempts have also been made to carry out solid-state polymerization of polyester to prevent drawdown, and to make the parison into a melt viscosity as high as it can be stably molded, and to use it for extrusion blow molding. However, although a high degree of polymerization polyester that certainly exceeds the limit of melt polymerization can be obtained by solid state polymerization,
Solid-state polymerization has a problem that the production efficiency is generally low because polymerization requires a long time, and an increase in cost cannot be avoided.

[0005] It is an object of the present invention to provide a polyester resin having fluidity suitable for extrusion blow molding.

[0006]

The gist of the present invention is to provide a polyester precondensate (A) 100 comprising an acid component containing an aromatic dicarboxylic acid and / or an ester-forming derivative thereof and a glycol component containing an aliphatic dialcohol. The hydrolyzable functional group-containing polymer (B) 0.1 to 100 parts by weight
This is a method for producing a polyester resin, which comprises adding 30 parts by weight and performing a polycondensation reaction.

[0007]

DETAILED DESCRIPTION OF THE INVENTION The polyester precondensate (A) used in the present invention contains an aromatic dicarboxylic acid and / or an ester-forming derivative thereof as a main acid component. Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, naphthalene-1,4 or 2,6-dicarboxylic acid, anthracenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, and 4,4′-diphenyletherdicarboxylic acid. These ester-forming derivatives include alkyl esters and aryl esters.

The aromatic dicarboxylic acid component in the polyester precondensate (A) used in the present invention accounts for 80% of all acid components.
Mol% or more, preferably 85% or more.
Preferably, it is contained in an amount of at least mol%. If the content of the aromatic dicarboxylic acid component is less than 80 mol%, the mechanical strength of the molded article may be reduced, and the productivity may be reduced. The polyester precondensate (A) in the present invention is:
As an acid component other than the aromatic dicarboxylic acid, an aliphatic dicarboxylic acid or an ester-forming derivative thereof may be contained in a total acid component in a range of less than 20 mol%, preferably less than 15 mol%. When these are contained in an amount of 20 mol% or more, the mechanical strength of the molded article is reduced. As the aliphatic dicarboxylic acid used in the present invention, oxalic acid,
Examples include succinic acid, glutaric acid, adipic acid, pimelic acid, sebacic acid, azelaic acid, dimer acid, 1,3 or 1,4-cyclohexanedicarboxylic acid.

The polyester precondensate (A) in the present invention preferably contains an ethylene glycol component in an amount of 50 mol% or more in all glycol components. And 7
It is preferable to contain 0 mol% or more. When the content of ethylene glycol is less than 50 mol%, there is a possibility that a problem such as a decrease in polymerization reactivity in a production step of the resin may occur,
There is a possibility that production efficiency may be reduced.

Other glycol components used for copolymerization in the present invention include diethylene glycol, triethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, dimer diol, and cyclohexane. Examples thereof include diol, cyclohexane dimethanol, and an adduct of bisphenol A ethylene oxide.

Further, a polyester initial condensate (A) such as bis-β-hydroxyethyl terephthalate can be directly used as a polycondensation component.

At the time of polymerization, an optional catalyst such as antimony trioxide or germanium oxide can be used as needed.

In the present invention, a polycondensation is carried out by adding a hydrolyzable functional group-containing polymer (B) to the polyester precondensate (A).

The hydrolyzable functional group contained in the hydrolyzable functional group-containing polymer (B) must be capable of reacting with a carboxylic acid terminal or a hydroxyl group terminal of the polyester.

Examples of the hydrolyzable functional group-containing polymer (B) which can be produced industrially at low cost include a polymer obtained by vinyl polymerization of a vinyl polymerizable monomer. In order to obtain a high fluidity improving effect with a small amount of the hydrolyzable functional group-containing polymer (B) added, the amount of the hydrolyzable functional group-containing monomer is preferably 5% by weight or more, Further, it is preferably at least 10% by weight.
On the other hand, although the reason is not clear, since the fluidity or appearance of the resin composition may be slightly lowered due to the excessively high content of the hydrolyzable functional group, the content of the hydrolyzable functional group may be slightly reduced. More preferably, the content of the monomer is 90% by weight or less.

Examples of suitable hydrolyzable functional group-containing monomers contained in the hydrolyzable functional group-containing polymer (B) include glycidyl methacrylate and α-hydroxyethyl methacrylate. Examples of the monomer having no hydrolyzable functional group which may be copolymerized therewith include styrene and methyl methacrylate.

Although methacrylic acid esters may be slightly transesterified under the conditions of polyester polymerization, the reaction rate is low, and under normal polyester polymerization conditions, for example, methyl ester of methacrylic acid is hydrolyzable. It can be considered not a functional group.

In the present invention, 0.1 to 30 parts by weight of the polymer (B) containing a hydrolyzable functional group is added to 100 parts by weight of the polyester initial condensate. If the amount of the hydrolyzable functional group-containing polymer (B) exceeds 30 parts by weight, excellent mechanical properties, gas barrier properties, chemical resistance, and the like of the polyester may be impaired, and a significant increase in viscosity during production may be caused. If the amount of the hydrolyzable functional group-containing polymer (B) is less than 0.1 part by weight, a clear fluidity improving effect cannot be obtained.

The molecular weight of the hydrolyzable functional group-containing polymer (B) is not particularly limited, but if it exceeds 300,000, the appearance of the molded article tends to deteriorate. More preferably, the molecular weight is 50,000 or less. A preferable composition stably obtaining the above-mentioned various properties is a hydrolyzable functional group-containing polymer (B) having a molecular weight of 50,000 or less (B) 0.1 to 30 based on 100 parts by weight of the polyester initial condensate (A).
Parts by weight, and to give a high degree of drawdown resistance as high as that of a solid-phase polymerized product to a polyester resin obtained by melt polymerization, the content of the hydrolyzable functional group-containing polymer is 0.3%. It is preferable that the amount be not less than part by weight.

When the hydrolyzable functional group-containing polymer (B) is added to the polyester prepolymer (A), the shape of the hydrolyzable functional group-containing polymer (B) is not particularly limited, but it facilitates dispersion. Powders are preferred because of the advantage.

The temperature at which the hydrolyzable functional group-containing polymer (B) and the polyester prepolymer (A) are added is not particularly limited, but is preferably from room temperature to 200 ° C. in view of operational problems.

Generally, melt mixing is known as a method for mixing a resin and other components. Melt mixing has the advantage of being able to mix multiple components over a wide range, but requires dedicated equipment. On the other hand, in the present invention, since the melting and mixing step can be omitted, the manufacturing process can be simplified, which is advantageous in terms of cost.

To produce such a polyester resin,
Any method is employed. For example, in the case of polyethylene terephthalate, a first-stage reaction for directly esterifying terephthalic acid and ethylene glycol or for transesterifying dimethyl terephthalate and ethylene glycol to obtain a polyester prepolymerized product
It is generally produced by a two-stage reaction (polycondensation reaction) in which the reaction product of the first step and the reaction product of the first step are heated under reduced pressure to distill off the generated glycol and polymerize. There is also a method of heating a polyester prepolymer such as bis-β-hydroxyethyl terephthalate under reduced pressure to distill off generated glycol and polymerize.

The polyester resin obtained by the present invention is most suitable for extrusion blow molding when the melt viscosity measured at 270 ° C. and a shear rate of 600 [1 / sec] is in the range of 1,000 to 20,000 [poise]. Flow characteristics can be obtained. Furthermore, in the polyester resin obtained by the present invention, in order to express high drawdown resistance at a lower melt viscosity than ordinary polyester, the melt viscosity of the blow molding polyester obtained by solid-state polymerization is less than 5,000 poise or less. Since the drawdown resistance suitable for extrusion blow molding can be obtained even in the melt viscosity range of, a resin for blow molding having high fluidity, which has not been obtained in the past, can be obtained.

The molded article obtained by using the polyester resin obtained in the present invention may be subjected to various conventionally known processing treatments, if necessary, in order to further impart specific performance, or may be added with an appropriate additive. Can be blended. Examples of the processing include irradiation of ultraviolet rays, α-rays, β-rays, γ-rays, electron beams, etc., corona treatment, plasma irradiation treatment, flame treatment, etc., treatment of resins such as vinylidene chloride, polyvinyl alcohol, polyamide, and polyolefin. Coating, laminating,
Alternatively, metal deposition and the like can be mentioned. Examples of additives include resins such as polyamide, polyolefin and polymethyl methacrylate, inorganic particles such as silica, talc, kaolin and calcium carbonate, pigments such as titanium oxide and carbon black, ultraviolet absorbers, release agents, and antistatic agents. Agents, flame retardants and the like.

The polyester resin obtained in the present invention can be used for materials such as hollow articles such as bottles, direct blow molded articles such as pipes and tubes, and extruded sheets, plates, blown films, molded articles by extrusion molding methods such as laminate coating and the like. Can be used as

[0027]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not particularly limited to the following methods.

(Examples 1 and 2) Bis-β-hydroxyethyl terephthalate (BHET) 100 (parts by weight) (75.8 (parts by weight) in terms of the weight of the produced polyester) and ammonium trioxide as a polycondensation catalyst were made of polyester. In addition to 0.04 (parts by weight) container based on the charged weight of raw materials, 150
C. and melted, and then powdered hydrolyzable functional group-containing polymers 1 and 2 synthesized by emulsion polymerization were mixed with BH
1 part by weight based on 100 parts by weight of ET, and 28
A polycondensation reaction was performed at 0 ° C. and 1 mmHg for 2 hours to obtain a polyester resin.

The melt viscosity was evaluated by using a Capillograph and measuring the viscosity when extruded at 270 ° C. and a shear rate of 600 [1 / sec].

The drawdown resistance was evaluated by using a Capillograph and measuring the number of seconds until the strand length reached 400 [mm] when extruded at 270 [° C.] and a shear rate of 60 [1 / sec].

The transparency was evaluated by visually observing the appearance of the strand-like sample obtained by the draw-down resistance evaluation.

Comparative Example 1 The procedure of Example 1 was repeated except that no polymer containing a hydrolyzable functional group was added.

Comparative Example 2 The procedure of Example 1 was repeated except that the amount of the hydrolyzable functional group-containing polymer was changed to 40 parts by weight. Adding a large amount of polymer is not only uneconomical,
It can be seen that the homogeneity of the obtained polymer is impaired and the transparency of the material is impaired.

[0034]

[Table 1]

Transparency-X: marked cloudiness, Δ: slightly cloudy,
○ Transparent except for thick part (lumps of discharged resin), ◎ Thick part is also transparent Representation smoothness-×: No surface gloss due to remarkable unevenness, △:
Surface gloss slightly reduced due to unevenness, good surface gloss. Functional group-containing polymer 1: Styrene / glycidyl methacrylate = 60/40 copolymer, coagulation of polymer obtained by emulsion radical polymerization controlled in molecular weight with n-octyl mercaptan. Dry powder. Weight average molecular weight 9000 Functional group-containing polymer 2: Styrene / α-hydroxyethyl methacrylate = 80/20 copolymer, coagulated and dried powder of a polymer obtained by emulsion radical polymerization of which molecular weight is controlled with n-octyl mercaptan. Weight average molecular weight 2
0000

[0036]

As described above, the polyester resin obtained by the method of the present invention can be used for direct blow molding of hollow containers such as bottles and parts such as pipes and tubes without impairing the processability and transparency of the polyester. It has excellent drawdown resistance that enables stable molding of molded articles, extruded sheets, boards, blown films, molded articles by extrusion molding methods such as laminate coating.

Claims (1)

[Claims] 1. A hydrolyzable functional group based on 100 parts by weight of a polyester initial condensate (A) comprising an acid component containing an aromatic dicarboxylic acid and / or an ester-forming derivative thereof and a glycol component containing an aliphatic dialcohol. A method for producing a polyester resin, comprising adding 0.1 to 30 parts by weight of a polymer (B) to be included and subjecting it to a polycondensation reaction.