JP2000007770A - Manufacture of polyester resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a polyester resin wherein while recovered polyethylene terephthalate is left melted, a necessary amount of an organic compound of tin is added thereto and uniformly dissolved, to which a desired polyhydric alcohol is added within a short time, thereby permitting the decomposition of the glycol to be performed within a short time without causing gelation as a whole. SOLUTION: R-PET from a PET bottle is melted at 260 deg.C or over, under which a tin compound is added to and uniformly dissolved therein, followed by further addition of a glycol in about 20 to 30 minutes. While keeping the temperature for about 15 to 20 minutes to make a uniform solution, a necessary amount of an α,β-unsaturated polybasic acid or its acid anhydride is added for polycondensation so as to prepare a polyester. Moreover, a required monomer is dissolved to obtain a polyester resin. The organic compound of tin is dibutyltin dilaurate or the like. The polyhydric alcohol is dipropylene glycol or the like when the monomer used in combination is styrene, or ethylene glycol or the like when using an acrylic monomer such as diallyl phthalate or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an unsaturated polyester resin (hereinafter abbreviated as polyester resin) using recovered polyethylene terephthalate (hereinafter abbreviated as R-PET).

[0002]

2. Description of the Related Art In recent years, attempts have been actively made to recycle PET and reuse it in various fields. One of the attempts is to use it as a raw material for polyester resin.

That is, terephthalic acid (dimethyl ester)
If the use of R-PET is superior to the production of polyester resin using ethylene glycol and α-β unsaturated polybasic acid in terms of raw material price, it has great industrial significance.

However, the conventional method, that is,
In the method of adding R-PET to glycol and decomposing the glycol by heating, it may take a long time to dissolve, and the amount of R-PET used is approximately 30% by weight (%) of the entire polyester (excluding monomers). Rank is the limit.

If an attempt is made to use a larger amount of R-PET, heating at a high temperature for a long time is required, and there is a risk that the decomposition of glycol is accelerated. Leads to an increase.

[0006] As a method of solving this drawback and increasing the amount of R-PET to be used as much as possible (for example, 30% by weight or more), glycols are added to R-PET which has been previously melted in advance, and the glycol is sequentially taken over time. A method for producing a polyester resin has been proposed in which after addition, glycol decomposition is performed until the mixture becomes homogeneous, and then a required amount of an α-β unsaturated polybasic acid or an acid anhydride thereof is added and esterification is further performed to a required stage. (Japanese Unexamined Patent Publication No.
No. 51438).

[0007]

That is, in this method, the glycol is sequentially added over several hours, and the melting R
If the total amount of glycol is to be added to the molten R-PET in a very short time (for example, a short time in minutes) by this method,
R-PET solidifies and precipitates almost instantaneously, and becomes a state of agar, making it impossible to stir.

Accordingly, the present inventors have repeatedly studied a method of adding glycol to molten R-PET in a very short time to synthesize a polyester resin in a short time.
Although the reason is not necessarily clear, if a desired amount of an organic compound of tin is added to the molten R-PET and then glycol is added, even if a large amount of glycol is added in a very short time (for example, a short time in minutes), It has been found that glycol decomposition can be performed within a short time without becoming a gel state.

That is, molten R-
When glycol is added to PET, it is presumed that the depolymerization of R-PET proceeds rapidly, but even if the total amount of glycol is almost instantaneously added, the entire gelation is not observed. There is no hindrance to the agitation as long as there is a partial suspended matter, and the liquid is uniformly liquefied in minutes.

In the synthesis of PET, various metal catalysts,
For example, it is known to use metal compounds such as titanium, manganese, germanium, chrome, and antimony,
The action of these metal catalysts and the above-mentioned tin organic compound,
Different effects.

The metal catalyst used for the synthesis of PET is PE
Although it is poorly effective as a catalyst for decomposition of T, organic compounds of tin are poorly effective as catalysts for PET synthesis and are presumed to be rarely used, but are useful as catalysts for PET decomposition. .

That is, when a large amount of glycol is added within a very short time of minute unit to molten PET to which metal compounds such as manganese and antimony are separately added, the whole immediately becomes an agar-like gel and can be stirred. On the contrary, in the case of a tin organic compound, on the contrary, even if a large amount of glycol is added in a short time, it dissolves in a short time to form a uniform solution, and the action and effect of the metal compound are determined. Will be different.

A method is known in which R-PET and glycol are mixed, a tin compound is added to the mixture, the temperature is raised, and R-PET is depolymerized.

However, in this method, since the reaction temperature cannot be raised above the boiling point of glycol, a small amount of R-PET can be used to decompose a large amount of R-PET, which is the object of the present invention, with a small amount of glycol. Requires long-term heating, resulting in the decomposition of glycol, coloring of the reaction contents,
In addition, insufficient decomposition of the produced polyester is inevitable, and therefore, it does not dissolve in a short time to form a uniform solution.

[0015]

According to the present invention, based on the above findings, R-PET is melted in an amount of 30 mol% or more and 90 mol% or less (1 mol of a repeating unit), and a polyhydric alcohol is added to decompose glycol. The present invention proposes a method for producing a polyester resin in which an organic compound of tin is added as a decomposition accelerator.

As the R-PET used in the present invention, regeneration from various molded articles can be used, a typical example of which is R-PET from a PET bottle. It is a suitable raw material.

The polyhydric alcohol used in the present invention does not need to be particularly restricted, but when the monomer used in combination is styrene, it is desirable to use a type having strong lipophilicity as much as possible in order to obtain a compatible polyester resin. Examples include propylene glycol, dipropylene glycol, neopentyl glycol, 1,2 butanediol, 2-methylpropanediol 1,3, 2-ethyl-2-butylpropanediol 1,3,1,4-cyclohexanedimethanol, 2 , 2,4, trimethylpentanediol 1,3, hydrogenated bisphenol A, bisphenol A propylene oxide adduct and the like. Of course, a combination of glycols is also possible.

When synthesizing a crystalline polyester resin using an allyl-based monomer such as diallyl phthalate, ethylene glycol, 1,4 butanediol, 1,6 hexanediol and the like can be used.

The proportions of PET and polyhydric alcohol used differ depending on the type of polyhydric alcohol.
PET repeating unit

[Formula 1] Is 1 mol, R-PET is 30 mol (%) or more and 90 mol (%) or less, and glycol is 70 mol (%) or less and 10 mol (%) or more.

The organic compound of tin used in the present invention is, for example, typically used for accelerating the reaction of a polyurethane resin, and examples thereof include dibutyltin dilaurate, dibutyltin oxide, tin octylate and the like. it can.

The amounts used are R-PET, glycol,
And 100 parts by weight of the total amount of the α-β unsaturated polybasic acid (or an acid anhydride thereof), 0.01 part by weight or more and 1 part by weight or less,
More preferably, the amount is 0.05 part by weight or more and 0.5 part by weight or less.

If the amount is less than 0.01 part by weight, the meaning of adding the decomposition catalyst is poor, and if the amount is more than 1 part by weight, the effect is not improved. In addition, other metal compounds may be used in combination with the organic compound of tin.

In the reaction sequence of the present invention, R-PET is kept in a molten state at a melting point or higher (260 ° C. or higher), a required amount of a tin compound is added and uniformly dissolved, and then a desired glycol is dissolved in a short time (almost). 10-30 minutes).

Further, if the temperature is maintained at 260 ° C. for about 15 to 20 minutes, the contents are converted into a homogeneous solution. Therefore, a necessary amount of an α-β unsaturated polybasic acid (or an acid anhydride thereof) is added to carry out polycondensation. Thereby, a polyester can be synthesized.

Further, necessary monomers are dissolved to form a polyester resin. Examples of the monomers used at this time include styrene, vinyltoluene, diallyl phthalate, diallyl isophthalate, diallyl terephthalate, triallyl isocyanocyanurate, 2, 6-dicarboxynaphthalenediallyl ester, trimethylolpropane triacrylate, bismaleimide, phenylmaleimide and the like can be mentioned.

The polyester resin using R-PET according to the present invention can be used in combination with inorganic and organic reinforcing materials, fillers, coloring agents, release agents, waxes, thermoplastic polymers and the like.

[0027]

EXAMPLES Next, examples will be shown below to facilitate understanding of the present invention. Example 1 Production of polyester containing about 68% by weight of PET (based on ester) A 1-liter separable flask equipped with a stirrer, a reflux condenser, a dropping funnel, and a thermometer equipped with a gas inlet tube was charged with R-PET [Yono PET Bottle Recycle Co., Ltd. )] 270 g (water content 1.4%), and melted at an internal temperature of 260 to 300 ° C. under a nitrogen stream.
0.7 g of dibutyltin dioxide was added for homogenization.

Further, 85 g of dipropylene glycol (R-
A PET to glycol ratio of 70 mol% to 30 mol%, glycol 5% increase) was added dropwise over about 5 minutes.

Initially, a white flake-like suspended matter of about 5 mm
Although about 6 precipitates, they did not hinder the stirring at all, and disappeared after about 10 minutes, and the R-PET which had a high viscosity at the time of melting became a very low-viscosity liquid.

When maintained at 260 ° C. for 2 hours in this state, it was completely dissolved in acetone, and it was recognized that the decomposition of R-PET in glycol was substantially completed.

Change the condenser to a fractionation type,
The temperature was lowered to 210 ° C., and 60 g of maleic anhydride was dropped by melting. After 30 minutes of esterification, finally reduce the pressure to 20 Torr.
When the time polycondensation was carried out, the acid value became 29.1. Therefore, the esterification was stopped, 0.06 g of hydroquinone was added, and 267 g (40% by weight) of styrene was added and dissolved at a temperature of 150 ° C. in an air stream.

The resulting polyester resin (A) was slightly cloudy, pale yellow, had a viscosity of 14.4 poise, methyl ethyl ketone peroxide 1.0 phr, cobalt naphthenate 0.2 phr, dimethylaniline 0.05 phr, and gelation time when adding 5 ppm of copper naphthenate. In 6 minutes, heat is generated rapidly, and the maximum heat generation temperature (JIS method)
The temperature reached 144 ° C.

The cast product had a flexural strength of 12.7 kg / mm ² , a flexural modulus of 310 kg / mm ² and a heat deformation temperature of 81 ° C.

Comparative Example 1 When dibutyltin dioxide was removed with the same composition as in Example 1, an agar-like gel-like substance immediately began to be generated when dipropylene glycol was dropped into the molten R-PET, and after 5 minutes of dropping, It was impossible to stir because the contents of the entire flask solidified.

Comparative Example 2 From the beginning, all the amounts of R-PET, dibutyltin dioxide and dipropylene glycol described in Example 1 were charged at once.
R-PE under reflux of dipropylene glycol (200 ~ 220 ℃)
Depolymerization of T was attempted, but after 12 hours, R-PET remained and no complete dissolution was observed, and the contents gradually became brownish brown and eventually became quite dark. Therefore, the reaction was stopped.

Example 2 Synthesis of a polyester resin having a PET content of about 70% (based on ester) R-PE was placed in a 1 L separable flask equipped with a stirrer, reflux condenser, dropping funnel with heater, and thermometer with gas inlet tube.
T [Yono PET Bottle Recycle Co., Ltd., water content about 1.4% by weight] 270 g, melt at 260 ° C., add 0.5 g of dibutyltin dioxide, dissolve uniformly, and add 68 g of neopentyl glycol at 130 ° C. It was melted and dropped in 5 minutes.

After the completion of the dropping, a small amount of white suspended matter remained, but it did not hinder the stirring at all, and disappeared after 10 minutes.
A low viscosity homogeneous solution was obtained.

After maintaining at 260 ° C. for 2 hours, the acetone dissolution test revealed that the glycol decomposition reaction was substantially completed.

The condenser was changed to a fractionating type, and the temperature was set to 210.
The temperature was lowered to 59 ° C., and 59 g of maleic anhydride was added dropwise by melting. After 30 minutes of esterification, polycondensation was finally advanced for 2 hours under a reduced pressure of 25 Torr. Discontinue at the stage of acid value 26.9, hydroquinone 0.
Add 07g, lower the temperature to 150 ° C,
320 g was added and uniformly dissolved. As a result, a slightly yellowish-brown liquid polyester resin (B) slightly thixotropy at room temperature and somewhat cloudy was obtained.

Comparative Example 3 A reaction was carried out by the same formulation and operation as in Example 2 except that dibutyltin dioxide was not used. After the addition of neopentyl glycol, the whole became a translucent agar-like solidified product, and stirring was not possible. It has become possible.

[0041]

In summary, according to the present invention, molten PE
When a polyhydric alcohol such as glycol is added to T to perform glycol decomposition, an organic compound of tin is used as a decomposition accelerator, so that a large amount of glycol can be added in a short time to cause glycol decomposition. it can.

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[Procedure amendment]

[Submission date] May 18, 1999 (1999.5.1
8)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J029 AA07 AB04 AC02 AD01 BA02 BA03 BA05 BA07 BA08 BA10 BD07A BD10 BF10 BF19 GA81 HA01 JB111 JB171 JC751 JD05 JF371 KB02 KE13 KG01

Claims (1)

[Claims] 1. Melting 30 mol% or more and 90 mol% or less (1 mol of a repeating unit) of the recovered polyethylene terephthalate and adding a polyhydric alcohol to decompose glycol to decompose an organic compound of tin. A method for producing a polyester resin, which is added as an accelerator.