JP2002069162A - Low specific-gravity polyester resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low specific-gravity polyester resin, easy in separating from PET in the recycling process. SOLUTION: This polyester polymer has terephthalic acid as a main carboxylic acid component and a compound expressed by chemical formula (1) and/or (2), as a diol component, wherein a grass transition temperature of this polyester is above 40 deg.C, and the density thereof is below 1.10 g/cm3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a bottle, a sheet,
Polyester resin used for films, injection molded products, and fibers. It is about.

[0002]

2. Description of the Related Art Polyethylene terephthalate (hereinafter referred to as PE)
Polyester resins represented by T) have been widely used as bottles, films, sheets and fibers because of their excellent mechanical properties, heat resistance and chemical resistance.

[0003] In recent years, the demand for PET containers has increased rapidly, and the amount of waste has also increased. Therefore, it is required to reuse PET waste. Attempts have been made to recycle PET (recovered PET) obtained by collecting and regenerating PET containers from the market. For example, JP-A-8-25322 discloses that recovered PET is used as a core layer,
A multi-layer PET bottle using virgin PET for the skin layer has been proposed.

A problem in the recycling process of the PET container is that no technique has been established for separating PET from other resins (such as PVC and polystyrene) mixed in a small amount into PET. In particular, printed films mounted on PET containers to identify the contents are usually made of polystyrene or polyvinyl chloride. If such a resin is mixed into PET, the color tone and transparency of the recovered PET deteriorate. Quality degradation such as degradation occurs. In addition, products made of polystyrene and polyvinyl chloride tend to be avoided due to environmental pollution problems.

As a method for solving such a problem, Japanese Patent Application Laid-Open No. 1-136722 and Japanese Patent Application Laid-Open No. 10-77335 have been proposed.
Japanese Patent Application Laid-Open Publication No. H11-163873 proposes using a polyester resin as a printing film. However, this method can improve the deterioration of the color tone and the transparency of the recovered PET due to the mixing of other resins, but when the printed ink is reused without detachment or decolorization, it becomes a reworked product of various colors. The problem is not solved.

Therefore, Japanese Patent Application Laid-Open Nos. 11-235770 and 11-237841 propose to use a printing film from which an ink layer can be easily removed. However, although this method allows the removal of the ink layer, it is treated in an alkaline aqueous solution at a high temperature, which causes a new decrease in the quality of the recovered PET, such as a decrease in viscosity.

On the other hand, a method of separating PET and another resin in water or an aqueous solution of an inorganic salt using the difference in specific gravity is considered to be the easiest method. Polyolefin-based resins may be mentioned as resins having a low specific gravity, but these resins have low heat resistance and deform at room temperature, and thus have insufficient physical properties as a printed film. Japanese Patent Application Laid-Open Nos. 11-235770 and 11-237841 propose a polyester resin having a low specific gravity composed of a specific compound. However, by using a long-chain aliphatic compound, heat resistance is reduced. Sexual decline is inevitable.

[0008] The present inventors consider that P in the recycling process.
We are working on the development of a low-density polyester resin that can be easily separated from ET, and have discovered that using a specific compound as a diol component can produce a polyester resin that is lighter than water or an inorganic salt aqueous solution and that has excellent heat resistance. The present invention has been reached.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to reduce the P
An object of the present invention is to provide a low specific gravity polyester resin which is easily separated from ET.

[0010]

The object of the present invention is to provide a polyester comprising terephthalic acid as a main dicarboxylic acid component and a compound represented by the formula (3) and / or (4) as a main diol component. Has a glass transition temperature of 40 ° C. or higher and a density of 1.10 g / c.
This is achieved by a polyester resin characterized by being not more than m ³ .

[0011]

Embedded image (R1 and R2 are hydrogen atoms or alkyl groups, and the total number of carbon atoms is 4 or more)

[0012]

Embedded image (R1 to R4 are a hydrogen group or an alkyl group, and the total number of carbon atoms is 3 or more)

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Terephthalic acid is mainly used as the acid component of the polyester resin of the present invention, but a small amount of other dicarboxylic acid components may be used. Specifically, adipic acid, oxalic acid, malonic acid, succinic acid, azelaic acid,
Aliphatic dicarboxylic acids such as sebacic acid, isophthalic acid,
Examples thereof include aromatic dicarboxylic acids such as 2,6-naphthalenedicarboxylic acid and diphenyldicarboxylic acid, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, and dimer acids. These can be used alone or in combination of two or more, but preferably less than 50 mol% of the whole dicarboxylic acid component.

The polyester resin of the present invention mainly uses a diol component represented by the following chemical formulas (5) and / or (6), but a small amount of other glycol components may be used. Specifically, ethylene glycol, diethylene glycol, butanediol, neopentyl glycol, propylene glycol, hexamethylene glycol, 1,
4-cyclohexanedimethanol, polyalkylene glycol, bisphenol A or bisphenol S diethoxy compound, and the like. These alone are 2
More than one species may be used, but preferably less than 50 mol% of the total diol component.

[0015]

Embedded image (R1 and R2 are hydrogen atoms or alkyl groups, and the total number of carbon atoms is 4 or more)

[0016]

Embedded image (R1 to R4 are a hydrogen group or an alkyl group, and the total number of carbon atoms is 3 or more)

The compounds represented by the above formula (5) include:
1,2-hexanediol, 1,2-decanediol,
Examples thereof include 1,2-dodecanediol, 1,2-octadecanediol, 1,2-nonadecanediol, and 1,2-eicosanediol. Among them, 1,2-decanediol is particularly preferred because of its good reactivity with terephthalic acid.

The compound represented by the above formula (2) includes 2
-Ethyl-1,3-hexanediol, 2,2-diethyl-1,3-propanediol, 3-butyl-1,3-
Propanediol, 2-butyl-2-ethyl-1,3-
Propanediol, 2,2-diisobutyl-1,3-propanediol, 2,2-diisopentyl-1,3-propanediol, 2,2-dihexyl-1,3-propanediol, 2,2-dioctyl-1,2 Examples thereof include 3-propanediol and 2,2-didecyl-1,3-propanediol. Among these, 2,2-diisopentyl-1,3-propanediol and 2,2-dioctyl-1,3-propanediol are particularly preferred because of their good reactivity with terephthalic acid.

The polyester resin of the present invention comprises a raw material mainly composed of terephthalic acid or an ester-forming derivative thereof and the compound represented by the above formula (5) and / or (6). , Tin,
It is produced by an esterification reaction step, a liquid phase polycondensation reaction step, and, if necessary, a solid phase polymerization reaction step, using at least one metal element-containing compound selected from the group consisting of zinc as a catalyst.

The esterification reaction step is carried out at 240 to 280 ° C.
At a pressure of 20 to 300 KPa. At this time, only water generated by the esterification reaction between terephthalic acid and the diol component is released out of the system. When a small amount of a basic compound is added in this esterification reaction step, a polyester having a small amount of side reaction products can be obtained. Examples of such a basic compound include triethylamine, tributylamine, and benzylmethylamine.
And quaternary amines such as quaternary amines, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, and trimethylbenzylammonium hydroxide.

The liquid phase polycondensation reaction step is carried out in the presence of at least one metal element-containing compound catalyst selected from the group consisting of antimony, titanium, germanium, tin and zinc.
The reaction is performed at a temperature of 50 to 300 ° C. and under a reduced pressure of 13.3 to 665 Pa. In the liquid phase polycondensation reaction step, the unreacted diol component is distilled out of the system from the low-order condensate of terephthalic acid and the diol component obtained in the esterification reaction step.

The polycondensation reaction catalyst used in the present invention includes germanium compounds such as germanium dioxide, germanium tetraethoxide and germanium tetrabutoxide; antimony compounds such as antimony trioxide, antimony pentoxide, antimony tartrate and antimony acetate;
Examples include titanium compounds such as tetrabutyl titanate, tin compounds such as tin acetate, and zinc compounds such as zinc acetate. Among them, a germanium compound is preferable in terms of color tone and transparency of the obtained resin. The polycondensation reaction catalyst is added as an aqueous solution or ethylene glycol solution having a predetermined catalyst concentration.

The amount of the polycondensation reaction catalyst to be added is 1 × 10 ⁻⁵ to 1 × per 1 mol of the acid component of the obtained polyester resin.
An amount of 10 ^-3 mol is preferred from the viewpoint of the rate of the polycondensation reaction.

In the liquid phase polycondensation reaction step, a stabilizer may be added to prevent side reactions such as thermal decomposition of the polyester resin. As stabilizers, trimethyl phosphate,
Examples include phosphoric acid esters such as triethylphosphoric acid and triphenylphosphoric acid, phosphorus compounds such as phosphorous acid and polyphosphoric acid, and hindered phenol compounds.

The amount of the stabilizer to be added is 1 × 10 ⁻⁵ to 1 × 10 ⁻³ mol per 1 mol of the acid component of the polyester resin to be obtained. It is preferable from the point of view.

The limiting viscosity of the polyester resin obtained in the liquid phase polycondensation reaction step of the present invention is 0.40 to 0.70 dl.
/ G. If necessary, a polyester resin having an intrinsic viscosity of 0.60 to 1.00 dl / g can be obtained by a solid-phase polycondensation reaction. The solid-phase polycondensation reaction is performed at 180 to 2
At a temperature of 20 ° C. under reduced pressure or in an inert gas atmosphere;
Performed for ~ 40 hours.

The polyester resin of the present invention has a glass transition temperature of 40 ° C. or more as measured at a heating rate of 10 ° C./min using a DSC (differential scanning calorimeter). It is preferably at least 50 ° C, more preferably at least 60 ° C. When the glass transition temperature is lower than 40 ° C., the heat resistance of the obtained molded product is insufficient.

The polyester resin of the present invention has a density of 1.
It is 10 g / cm ³ or less. Preferably 1.00
g / cm ³ or less, more preferably 0.95 g / cm ³ or less. It is preferable that the density be in this range because it becomes easy to separate from the PET resin in water or an aqueous solution of an inorganic salt due to a difference in specific gravity.

For example, the specific gravity of a 10% by weight aqueous solution of sodium carbonate is 1.1008 g / c at ordinary temperature (25 ° C.).
m ³ , and the specific gravity of a 16% by weight aqueous solution of sodium chloride is 1.11401 g / cm ^{3 at} ordinary temperature (25 ° C.).
(Edited by The Chemical Society of Japan, Basic Handbook of Chemical Handbook II). When the PET resin and the polyester resin of the present invention are simultaneously introduced into such an inorganic salt aqueous solution, the PET resin settles at the lower part of the solution, and the polyester resin of the present invention floats at the upper part of the solution, so that it can be easily separated. is there.

The polyester resin of the present invention is formed into a sheet, film, bottle, or fiber by a known method. For example, in the case of a film, it can be obtained by stretching an unstretched film obtained by an arbitrary method such as an extrusion method or a calendering method as necessary.

[0031]

The polyester resin of the present invention has a lighter specific gravity than water or an aqueous solution of an inorganic salt and has a low P when recycled.
It is easily separated from ET resin and has excellent heat resistance, and can be widely used as bottles, sheets, films, injection molded products, and fibers.

[0032]

The present invention will be described below in detail with reference to examples. Measurement and evaluation of each physical property were performed according to the following methods.

(1) Intrinsic viscosity (IV) Phenol / tetrachloroethane =
Dissolve in a 60/40 (weight ratio) mixture and use an automatic viscosity measurement device (SS-270LC manufactured by Shibayama Scientific) at 20 ° C.
Was measured.

(2) Glass transition temperature (heat resistance Tg) The glass transition temperature was measured at a heating rate of 10 ° C./min using a DSC (differential scanning calorimeter) manufactured by PerkinElmer.

(3) Density: Density was measured by a density gradient method using an n-heptane / carbon tetrachloride mixed solution. (Measurement temperature 23.0 ° C)

(4) Determination of polyester constituents (NM
R measurement) A polyester resin was dissolved in a mixed solution of trifluoroacetic acid and chloroform in a ratio of 1: 1 (weight ratio), and tetramethylsilane was mixed as a standard, and the mixture was subjected to Varian FT-NMR.
(Model 300MG).

(5) Separability from PET resin 1 A 10% by weight aqueous solution of sodium carbonate at room temperature (25 ° C.)
Weight 1.100 g / cm ^Three) PET resin and polyester
The resin simultaneously and wait for 10 minutes
Measured. ：: PET resin settles at the lower part of the solution and is a polyester resin
Floats above the solution. ×: Both PET resin and polyester resin settle.

(6) Separability from PET resin 2 The PET resin and the polyester resin were simultaneously introduced into pure water (specific gravity 0.997 g / cm ³ ) at room temperature (25 ° C.).
The state after standing for minutes was observed. ：: PET resin sediments at the bottom of the solution, and polyester resin floats at the top of the solution. ×: Both PET resin and polyester resin settle.

(7) Heat Deformation Temperature (Heat Resistance Test) After drying the polyester resin of the present invention, it was melt-molded into a JIS No. 1 bending test specimen having a width of 6.0 mm, a height of 13.0 mm and a length of 130 mm, and load deflection. Temperature tester (Toyo Seiki Seisakusho heat distortion tester model S3-MH)
Was measured according to JIS K7207. (Heating rate 120 ° C./hour, load 45.1 N / cm ² ) ：: heat deformation temperature 40 ° C. or more. X: Heat deformation temperature of less than 40 ° C.

Examples 1 to 18 and Comparative Examples 1 to 6 A predetermined amount of a dicarboxylic acid component and a glycol component were charged into a stainless steel autoclave so that the molar ratio of the glycol component to the acid component was 1.2. , 0.2
The esterification reaction was performed at MPa. After completion of the esterification reaction, a predetermined amount of germanium dioxide was added as a polycondensation catalyst, and the polycondensation reaction was performed at 285 ° C. under a reduced pressure of 133 Pa. Germanium dioxide was added as a 0.8% by weight aqueous solution. The polyester after the polycondensation reaction was extruded in a gut shape and then cut using a cutter. The composition of the obtained polyester resin analyzed by NMR, and
Tables 1 to 3 show the physical property evaluation results.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

[Table 3]

Continued on the front page F term (reference) 4J029 AA03 AC01 AC02 AD07 AD10 AE01 AE02 AE03 BA02 BA03 BA05 BA07 BA08 BA09 BA10 BD07A BF09 CA01 CA02 CA03 CA04 CA06 CB05A CB06A CB10A CC06A CD03 GA74 JE182

Claims (2)

[Claims] 1. A low specific gravity polyester resin having a glass transition temperature of 40 ° C. or more and a density of 1.10 g / cm ³ or less. 2. A polyester comprising terephthalic acid as a main dicarboxylic acid component and a compound represented by the following formula (1) and / or (2) as a main diol component,
The glass transition temperature of the polyester is 40 ° C. or higher,
2. The low specific gravity polyester resin according to claim 1, wherein the density is 1.10 g / cm ³ or less. Embedded image (R1 and R2 are each a hydrogen atom or an alkyl group, and the total number of carbon atoms is 4 or more) (R1 to R4 are a hydrogen group or an alkyl group, and the total number of carbon atoms is 3 or more)