DE1770044A1 - Crystal clear, thermoplastic polyester-based molding compounds and process for their production - Google Patents

Description

Crystal clear, thermoplastic molding compounds based on polyester and ancestors for their hearing

position.

Linear, saturated polyesters made from aromatic dicarboxylic acids and aliphatic diols such as polyethylene terephthalate are, according to manufactured using the usual ancestors, as thermoplastic Masses are hardly suitable for the production of moldings. Caused due to the naturally only slight, but on the other hand not completely preventable, tendency of these polyesters to crystallize namely, molded bodies are obtained whose properties are as follows winig satisfied that a technical usability is practically not given.

As can be seen from the Dutch patents 6 511 Jhh and 6 610 128, it is nevertheless possible to process the aforementioned linear polyesters, in particular the easily accessible polyethylene terephthalate, into usable thermoplastic moldings if measures are taken to increase the tendency to crystallize and to improve their formation a crystalline structure of the molded body can be taken. These measures consist in first using so-called nucleating agents, which are distributed inorganic substances such as calcium carbonate, calcium magnesium carbonate, magnosium silicates, talc, etc. with a particle size of untox ' Zfii. and this Maswo

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then squirted into molds kept at 140 ° C. This way it is achieved that the material for crystallization is on a long enough for the crystallization is kept at a favorable temperature.

The moldings obtained after this processing, however, only have sufficient impact strength if polyethylene terephthalate with a particularly high molecular weight is used. The production of such PoIyäthylenterephthalats, the reduced specific viscosity (measured in 1 ', iiger solution i' henol / Tetrachlprüth ^ n 60: KO at 25 ° C) in the range between 1, 2 - is 1.5 (dl / g), requires a separate operation, which consists of a post-condensation in the foster phase, for example according to the information in German Patent 930,231.

Moldings produced according to the described method are always opaque due to their crystalline initiation thus divorce for a number of uses at | a.

The present invention now relates to a process for producing amorphous, transparent, colorless, thermoplastic compositions based on linear, saturated polyesters which can be processed on conventional injection molding machines to give crystal-clear moldings with particularly high impact strength and high surface gloss.

This process for the preparation of linear, saturated polyesters suitable for thermoplastic molding compositions is characterized in that 1 mol of lower esters of aromatic dicarboxylic acids, which can optionally contain up to 10 mol / o of esters of aliphatic dicarboxylic acids with k to 10 carbon atoms, nit mixtures of 2 to 4 moles of ethylene glycol and 0.05 to 1 mole of a diol of the formula HO-CH ^ -CR ^ -CII -OH,

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where R ₁ and H ₀ denote hydrogen or a linear or a verso ₁ JtOn aliphatic reads with 1 to k carbon atoms, transesterified in a manner known per se and the resulting oil then polycondensed in a manner which is also known.

The esters used as starting materials are methyl, ethyl, propyl, or isopropyl esters of terephthalic acid and, if necessary, isophthalic acid. Preference is given to using dimethyl terephthalate. Up to 10 mol of the aromatic dicarboxylic acid esters can also be replaced by esters of aliphatic dicarboxylic acids with k to 10 carbon atoms, such as boron stone, adipic acid or sebacic acid methyl, ethyl, propyl or isopropyl esters.

The transesterification of the lower dicarboxylic acid esters is carried out with mixtures of 2 to k moles of ethylene glycol and 0.05 to 1 mole of one or more higher diols of the general formula HO-CH ₂ -CH-R ₀ -C] I ₀ -OlI, where R ₁ and H _{0 can be} hydrogen or a linear or branched aliphatic radical with 1 to carbon atoms. Suitable higher diols are, for example, 2-ethyl-L> -butyl-propanediol (1,3) 2,2-diethyl-propanediol (1,3), 2-methyl-2-propyl-propanediol (1,3) and preferred 2,2-dimethylpropanediol (1,3), known under the name neopentyl glycol. The molar ratio of dicarboxylic acid ester to diol in the transesterification should be 1: 2.05-1.5. In some cases it can be useful to carry out the transesterification in such a way that the individual components are added one after the other to the lower diacid esters. The latter mode of operation is particularly appropriate when the ethylene glycol component is to make up only a small proportion in the subsequent polyester. In this case, the whole or predominant amount of the (substituted) propanediol is first reacted and the transesterification is then completed with the excess of ethylene glycol.

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At dor Uinusteruii, -, which is carried out in the temperature range between about 150 and 220 ° C, the presence of catalysts is essential. Suitable, known catalysts are salts of alkaline earth and transition metals, such as calcium acetate, manganese acetate and titanium compounds. The catalysts are used in amounts of from 0.005 am 0.5 mol ^1, "based on the low dicarboxylic acid ester used. The transesterification is complete when the lower alcohol formed has been driven off from the reaction mixture.

The polycondensation involved in the transesterification is carried out in a known manner in the presence of the customary polycondensation catalysts such as Sb ,, O,., GeO ₀ or GeIiPQ ,. carried out at temperatures around 285 C ^unu under reduced pressure. The usual phosphorus compounds, e.g. phosphorous acid or tri-

phenyl phosphite and others.

The erfindungsgemäü polyesters produced in the Mononterenelnheit to 1 mole Dicarbonsaur.e 95 to 0 Mo I ^ jithylenglycol and 5 to 100 moles ^1; '' of the substituted or unsubstituted 1,3-propanediol. They have reduced specific viscosities of 0.7 to 1.1 dl / g, which can be increased without difficulty through post-condensation in the solid phase. The granulate, which can be produced from the melt in a known manner, is completely colorless and, after drying, additional measures such as the addition of glide waxes can be processed effortlessly on the injection molding machine to give moldings with the properties mentioned.

The following examples illustrate the process in more detail

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example 1

680 g of dimethyl terephthalate (3 »5 mol) are added to a mixture of 500 g of glycol (8.3 mol) and 72.8 g of noopentyl glycol (0.7 mol) in the presence of 125 ml; Manganese acetate at 150 to .22O C uni- (perester. The split off methanol is continuously distilled off during the transesterification. After the transesterification is complete, 250 mg GelIIPO ,, are added, whereupon the excess glycol is removed by distillation and at 0, ^ Torr and 285 C polycondensed. Dio polycondensation is over after 2½ hours. The melt is poured into water. The solidified polyester is comminuted, dried at 100 to 150 ° C. in vacuo and stored in the absence of moisture. It shows a reduced specific viscosity of 0.8 dl / g (measured in fig solution in phenol / totrachloroethane 60: k0 at 25 ° C.). The glass transition temperature of approx. 80 C agrees with that of an unmodified polyethylene terephthalate. Crystal-clear, smooth moldings which have a high degree of toughness can be produced by injection molding.

example

19 ¹ L g of dimethyl terephthalate (1 mol) are gradually heated from 50 mg of manganese acetate with 104 g (1 mol) of neopentyl glycol to 210 in Gogenwart. At this temperature, gehulten so long, no elimination of methanol bie longer be observed. Is added then 100 g of ethylene glycol (1.65 mol), terminates the transesterification is distilled after addition of 75 mg GeIIPO "excess glycol from and polycondensed 2 hours boi 285 ° C and 0, b Torr. The resulting polyester has a reduced specific viscosity of 0.7 dl / g.

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Example 3

194 g of dimethyl terephthalate (1 mol) are as described in Example 2, with 132 g of 2-methyl-2-propyl-propanediol (1,3) (1 mol) and 100 g of ethylene glycol in the presence of 50 μg of manganese acetate and then exhaled with addition of 75 mg GellPO ^ at approx. 0.2 k Torr and 285 ° C for 2 hours. A colorless, crystal-clear polyester with a reduced specific viscosity of 0.7 dl / g is obtained.

Example k

A dry polyester granulate produced according to the invention according to Example 1 was injected into a mold cooled with water in the usual Veiso at a cylinder temperature of 260 to 270 C under an injection pressure of about 120 atU and a holding pressure of 70 to 80 atU using a Stübbe injection molding machine . Easily demoldable, distortion-free, crystal-clear, completely homogeneous injection molded parts with a remarkably high surface gloss were obtained.

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Claims (3)

Sponsorship claims: 1. Process for the preparation of linear, saturated polyesters suitable for thermoplastic formulas, characterized in that 1 mole of low eater of aromatic dicarboxylic acids, and possibly up to 10 Μοί ', ο of esters of aliphatic dicarboxylic acids with 4 to 10 carbon atoms are contained can, with mixtures of 2 to k moles of Xthyloniylycol and 0.05 to 'moles of a diol of the formula 110-CII ₂ -CH ₁ It ₀ -CII ₀ -OII, wherein H ₁ and H _{0 are} hydrogen or a linear or branched aliphatic radical with 1 to h carbon atoms means transesterified in a manner known per se and the esters obtained are then polycondensed in a manner likewise known. 2. Use of linear, saturated polyesters consisting of aromatic dicarboxylic acids, which can optionally contain up to 10 moles of aliphatic dicarboxylic acids with h to 10 carbon atoms, and mixtures consisting of 95 to 0 moles; Ethylene glycol and 5 to 100 MoI ^ of a diol of the formula HO-ClL-CH ₁ H ₀ -ClI ₀ -OIf, in which R _{1 and H 0 are} hydrogen or a linear or branched aliphatic radical with 1 to h carbon atoms are built up , for the production of crystal clear, thermoplastic moldings. 3. Glass-clear, thermoplastic molding compounds consisting of linear, saturated polyesters of aromatic dicarboxylic acids, which may contain up to 10 mol of aliphatic dicarboxylic acids with k to 10 carbon atoms, with mixtures of 95 to 0 mol of ethylene glycol and 5 to 1.00 MoI ^ of a diol of the formula 110-ClI ₀ -CH ₁ H ₀ -CH ₀ -OII, in which H ₁ and R _{0 are} hydrogen or a linear or branched aliphatic radical having 1 to h carbon atoms. 10 9 8 3 9/1695