JPH11181067A - Production of unsaturated polyester resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an unsaturated polyester resin (hereinafter abbreviated to polyester resin) using a recovered polyethylene terephthalate (hereinafter abbreviated to R-PET) as a raw material, more precisely a method for producing a polyester resin using an R-PET having a prescribed metal content. SOLUTION: In this method for producing an unsaturated polyester resin by sub jecting a polyethylene terephthalate to glycol decomposition and carrying out polycondensation by adding an α,β-unsaturated polybasic acid or its acid anhydride, a recovered polyethylene terephthalate having <=1,000 ppm of total content of heavy metals selected from zirconium, vanadium, chromium, molybdenum, manganese, iron, nickel, lead, tin and copper is used. Since a polyester resin having shelf stability and curability can be obtained from an R-PET as a raw material, a preferable raw material for a molding material can be obtained at an extremely low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a recovered polyethylene terephthalate (hereinafter abbreviated as R-PET).
The present invention relates to a method for producing an unsaturated polyester resin (hereinafter abbreviated as “polyester resin”) using as a raw material, and more particularly to a method for producing a polyester resin using R-PET having a specified metal content as a raw material. is there.

[0002]

2. Description of the Related Art In recent years, from the standpoint of environmental protection, recycling of various materials has been actively studied, and the effective use of R-PET is one of them. In particular, recycling of PET bottles has attracted great social interest. In.

[0003] Naturally, the method of using R-PET is directed to the conventional field of use of PET, but it is also known to use it as a raw material of polyester resin. However, although research is being conducted, its commercialization is inactive.

The reason is that the cost of R-PET is high, and
-It is considered that the purity of PET is not always constant and may affect the quality of the polyester resin using the same.

One of the reasons for the high cost of R-PET is that
The expense of removing the water during the production of PET. In other words, since a large amount of water is used in processes such as dust removal and label peeling in the recovery process, the water content before final pelletization is 0.1% by weight or less, preferably 0.05% by weight or less. Otherwise, the molecular weight will be reduced in the melting step of pelletization and it will not be possible to use it depending on the application, and the cost required for removing water will reach 40% of the production cost of R-PET. ing.

On the other hand, a method for producing a polyester resin as a raw material of a molding material by subjecting PET to glycol decomposition and further adding an α-β unsaturated polybasic acid or an acid anhydride thereof to perform polycondensation is known. Although known, the present inventors have:
As a result of repeated studies on R-PET as a raw material for producing this polyester resin, R-PET was
It is not always necessary to form pellets, but flakes are sufficient, and it has been found that mixing of water does not hinder the decomposition of R-PET in glycol.

Therefore, the present inventors have proposed a method for producing a polyester resin in which R-PET is glycol-decomposed first and then polycondensation is carried out by adding an α-β unsaturated polybasic acid or an acid anhydride thereof. (Japanese Patent Application No. 9-237889).

[0008]

On the other hand, as to the purity of R-PET, as is well known, R-PET has undergone a number of processes such as collection, crushing, label removal, and sorting of PET bottles. , Wash as much as possible R-PE
Efforts have been made to remove impurities other than T.

However, R-PE contaminated under various environments
It is difficult to maintain T at a constant purity. Among them, heavy metals are not only originally added as a catalyst for the synthesis of polyethylene-terephthalate, but also include those that adhere as metals due to contamination during the recovery. .

[0010] In contrast, the effect of using R-PET contaminated with such a metal as a raw material for the production of the polyester resin as described above, for example, the effect on the curability of the obtained polyester resin, storage, and the like. No effect on stability has been studied.

The inventors of the present invention have studied the effects of the polyester resin obtained by the above-described method on the curability and storage stability. As a result, in general, in the synthesis of polyethylene-terephthalate, metals such as titanium, antimony, and germanium were used. Compounds are used, but these metals have little effect on the curability and preservability of the polyester resin. However, the periodic table (long-period type) IVB, especially zirconium, Vanadium V, chromium VIB, molybdenum, VIIB manganese, VI
It was found that heavy metals such as iron (II), nickel, copper (IB), lead (IVA) and tin (IVA) tended to significantly impair the storage stability of the polyester resin. The organic compounds of tin include those added as a glycol decomposition catalyst.

[0012] For example, vanadium and iron tend to impair the storage stability of the polyester resin. Among them, manganese tends to impair the preservability of the molding material in combination with an organic peroxide catalyst, and the same applies to the copper compound. .

According to the study of the present inventors, R-
When PET is used as a raw material, the total content of the above heavy metals is
It must be below 1000 ppm, preferably below 100 ppm.

When the total content of the above heavy metals is 1000 ppm or more, the storage stability of the obtained unsaturated polyester resin is impaired.

It should be noted that the presence of the above heavy metals does not necessarily affect the polyester resin, but may have a favorable effect if the value is less than the specified value.
The presence of copper above pm almost completely inhibits the curing of the polyester resin and the resin does not cure, but the presence of 0.5-50 ppm of copper organic acid salt is more likely in a system with cobalt organic acid salt. In some cases, it acts as an accelerator.

[0016]

According to the present invention, based on the above findings, the total content of heavy metals selected from zirconium, vanadium, chromium, molybdenum, manganese, iron, nickel, lead, tin and copper is reduced. R-PET below 1000ppm
To produce a polyester resin which is subjected to glycol decomposition using as a raw material, and further subjected to polycondensation by adding an α-β unsaturated polybasic acid or an acid anhydride thereof.

The R-PET used in the present invention is desirably a colorless type mainly made of film scraps and PET bottles, and a colored type is a type containing a large amount of pigments and heavy metals. This is undesirable because it can inhibit curing.

The quantitative analysis of heavy metals contained in R-PET is conveniently carried out by a spectrophotometric method. This is done by selecting a specific compound and a system that develops color. The details are described in, for example, Handbook of Analytical Chemistry (edited by the Japan Society for Analytical Chemistry, III Inorganic Edition), and the necessary analytical methods using instruments and equipment are also prepared. ing.

The R-PET used in the present invention may contain 0.1 to 10 parts by weight of water with respect to 100 parts by weight of R-PET, regardless of the amount of adhering water and the amount of adsorbed water.

In addition, when water is removed from the filter after washing with water, 3 to 7 parts by weight of water is removed, and when water is removed by a centrifuge, 0.5 to 1.5 parts by weight of R-PET is removed.
R-PET having such a water content can be subjected to glycol decomposition as it is.

In decomposing R-PET with glycol,
If necessary, an organic compound such as tin is used as a catalyst for promoting decomposition together with the desired glycol, and the reaction is carried out by heating.

The type of glycol used for the glycol decomposition is selected according to the application. For example, when used for a molding material requiring crystallinity, a type that forms a crystalline polyester resin such as ethylene glycol, 1,4 butanediol, 1,6 hexanediol, 1,4 cyclohexane dimethanol, hydrogenated bisphenol A, etc. Is useful.

When it is necessary to dissolve in monomers such as styrene, propylene glycol, dipropylene glycol, neopentyl glycol, 1,3 butanediol, 2,2,4 trimethylpentanediol 1,3, and alkylene of bisphenol A Rather, a type such as an oxide adduct that breaks the crystallinity and allows the solubility of the monomer is desirable. Of course, two or more of these can be used in combination.

When the ratio of R-PET to glycol is calculated assuming that R-PET in the following formula is 1 mol, R-PET is 10 mol (%) or more and 90 mol (%) or less, more preferably 20 mol (%).
Not less than 80 mol (%) or less.

[0025]

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Naturally, the required amount of glycol is 90 mol (%) or less, 10 mol (%), excluding the portion lost due to distillation during the reaction.
As described above, it is more desirably 80 mol (%) or less and 20 mol (%) or more.

When the amount of R-PET used is less than 10 mol (%), the meaning of using R-PET is poor. When the amount used is 90 mol (%) or more, the amount of R-PET used is less than the amount of α-β unsaturated polybasic acid. The ratio is 10
Mol (%) or less, the resulting polyester resin has low reactivity, and has adverse effects on strength and other physical properties,
The solubility in a monomer such as styrene is significantly impaired, resulting in lack of practicality.

After the glycol decomposition, α-
A β-unsaturated polybasic acid (or an acid anhydride thereof, hereinafter omitted) must be added, and examples thereof include maleic anhydride, maleic acid, fumaric acid, and itaconic acid.

The proportion of the α-β unsaturated acid used is selected to be equimolar or less than that of the glycol.

Although not an essential component, a modifying saturated or unsaturated polybasic acid (or acid anhydride thereof) can be added to impart versatility to the polyester resin.

These include, for example, phthalic anhydride, isophthalic acid, tetrahydrophthalic anhydride, endomethylenetetrahydrophthalic anhydride, adipic acid, sebacic acid and the like.

As a monomer for dissolving and curing the formed polyester resin, styrene is preferable, and vinyl toluene can be used in addition to the above. In the case of a crystalline polyester resin, an allyl monomer is used in combination. There is.

In addition, the polyester resin obtained by the present invention may be used in combination with various reinforcing materials, fillers, coloring agents, modifying polymers, oligomers, mold release agents, and the like. Of course you can.

[0034]

In summary, the present invention provides an R-PET
As a raw material, a polyester resin having storage stability and curability can be obtained, so that a suitable raw material for a molding material can be obtained at an extremely low cost.

Next, examples will be shown below to help understanding of the present invention. In this example, since it was difficult to find a sample containing an appropriate amount of heavy metals, a desired amount of metal was added.

Example 1 In a 1 L separable flask equipped with a stirrer, a reflux condenser, a thermometer and a gas inlet tube, a colorless, transparent flake-like product of "Yoyo PET Bottle Recycle Co., Ltd." was used as R-PET. Pets were used.

As a result of analysis of this R-PET, 1.9 ppm of iron, 4.5 ppm of aluminum, 6 ppm of lead, 0.06 ppm of copper, and 0.3 ppm of manganese were detected as heavy metals other than titanium and germanium.

230 g (1.2 mol) of this R-PET, 96 g (1.07 mol) of 1,2 butanediol and 0.6 g of dibutyltin oxide (500 ppm as tin) were charged, and glycol decomposition was carried out for 8 hours under reflux of 1,2 butanediol. After that, the condenser was replaced with a fractionation type, 78 g (0.8 mol) of maleic anhydride was added, and polycondensation was carried out in a nitrogen gas stream at 200 to 205 ° C.
As a result, the reaction was stopped at an acid value of 29.7, and the mixture was a tan transparent liquid.

0.13 g of hydroquinone was added to the mixture in an air stream.
At 140 ° C., it was dissolved with 260 g of styrene. The initially transparent content began to become turbid with a decrease in temperature, and turned into a yellow-brown, slightly opaque liquid polyester resin at room temperature. Viscosity 5.9
Poise.

To these, organic acids of the following metals in Examples 1 to 6 were added in calculated amounts as (octylate) metals.

Example 1 Blank (500 ppm tin) Example 2 1 ppm as copper Example 3 3 ppm as copper Example 4 9 ppm as copper Example 5 10 ppm as manganese Example 6 5 ppm as iron

Assuming a molding material, t-butyl peroxybenzoate as an organic peroxide catalyst was added in a ratio of 2 parts by weight to 100 parts by weight of the resin, and 2/3 of the amount was added to a commercially available candle bottle.
The volume was filled and sealed with polyethylene. This was placed in a constant temperature bath at 60 ° C., and a storage stability verification test was performed. The results are shown in Table 1.

Comparative Example In a 1 L separable flask equipped with a stirrer, a fractionating condenser, a thermometer and a gas inlet tube, 96 g of 1,2 butanediol (1.
07 mol), 82 g (1.32 mol) of ethylene glycol, 233 g (1.2 mol) of dimethyl terephthalate and 0.8 g of tetraisopropyltitanium.
A methanol removal reaction was carried out at 0 ° C., and when methanol distillation was completed, 76 g (0.8 mol) of maleic anhydride was added thereto.
The polycondensation was carried out in a nitrogen gas stream at 0 to 205 ° C. Acid value 29.
The reaction was stopped at 4, and 0.13 g of hydroquinone was added and dissolved in 260 g of styrene under an air stream. A pale yellow transparent polyester resin was obtained with a viscosity of 6.1 poise. To this, a storage stability verification test was performed by the above-mentioned method without adding a metal organic acid, and the results are shown in Table 1.

[0043]

That is, it is clear that the presence of the heavy metal significantly shortens the storage stability, and the molding material, ie, SMC
And cannot be used for BMC.

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[Procedure amendment]

[Submission date] February 5, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0040

[Correction method] Change

[Correction contents]

Example 1 500 ppm tin Example 2 1 ppm as copper Example 3 3 ppm as copper Example 4 9 ppm as copper Example 5 10 ppm as manganese Example 6 5 ppm as iron

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0043

[Correction method] Change

[Correction contents]

[0043]

Claims (1)

[Claims] 1. A method for producing an unsaturated polyester resin, comprising subjecting polyethylene-terephthalate to glycol decomposition and further adding an α-β unsaturated polybasic acid or an acid anhydride thereof to carry out polycondensation, wherein zirconium is used as polyethylene-terephthalate. Vanadium, chrome, molybdenum,
A method for producing an unsaturated polyester resin, comprising using polyethylene-terephthalate having a total content of heavy metals selected from manganese, iron, nickel, lead, tin, and copper of 1000 ppm or less.