DE1694202A1 - Thermoplastic molding compounds made from polyesters - Google Patents

Description

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Thermoplastic molding compounds made from polyesters

It is from the Dutch patent documents 6 511 744 and 6 610 128 "known to crystalline polyester molding compounds containing linear, saturated polyesters of aromatic dicarboxylic acids Process moldings. For example, polyethylene terephthalate can be injected into molded bodies, their crystallization rate and degree of crystallization can be influenced by adding suitable nucleating agents. The moldings obtained in this way have only moderate impact strength.

From the German patent specification 1 102 820 it is also known to Add polyesters, polypropylene or poly-4-methylpentene-1. Molding compositions with improved dimensional stability are obtained.

It has now been found that thermoplastic Fcrnmasson consisting of a mixture of
a) linear saturated polyesters of aromatic SicirLon-üäureri and; ;, · -IHmeniVllo ί: 1ο ^; -; ΐ ^Λ η Ui: n ^: - nli 1; ϋη. ^; : ΐοοΐ. ^: ίΓ. ; ci-buiuwi · :, · -.ν.

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with saturated aliphatic or c.'cloaliph'itinchen diols

b) aliphatic polyethers in Menken from 0.1 to 25, preferably 0.5 to 10 percent by weight of the total mishage, excellent Have properties.

Surprisingly, the impact strength of the modified Polyester increases without losing hardness or abrasion resistance adversely affected .verden.

One can; s according to the invention. en molding compositions add nucleating agents which, as is known, increase the rate of crystallization of the polyester composition and ensure that the polyester moldings achieve a good degree of crystallization. Moldings with a good degree of crystallization are dimensionally stable even above the glass transition temperature and do not shrink. In a known manner, finely divided inorganic substances which are insoluble in polyester fiber masses, such as calcium carbonate, aluminum silicate or talc, can be used as nucleating agents. The addition of the nucleation.3mitt .Is can take place at various points in the production process of the polyester fiberglass. So!: The nucleating agent can be added during the polycondensation during the production of the starting polyester, for example. The nucleating agent can also be mixed with the polyether to the polyester. riltt :! i: \ iem ro tiex- ^ ndon vessel handling ^

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Melt the truder, press it out while cooling and granulate it again.

A preferred linear saturated polyesters of aromatic dicarboxylic acids it is preferably ^poly:; thylenglyklterephthalat used. Other polyesters can also be used, for example! ülycyclohexane-1,4-dimethylol-terephthalate can be used. Llan can also use modified Polyäthyleiiierephthalate, which besides terephthalic acid also contain other aromatic or aliphatic dicarboxylic acids as basic units, for example naphthalenediearboxylic acid-2.6 or adipic acid. It is also possible to use modified polyethylene terephthalates which, in addition to ethylene glycol, also contain other aliphatic diols, such as neopentyl glycol or batanediol-1.4, as alcoholic components.

The polyesters should have a reduced specific viscosity dl ⁷ g (measured in a 1 $ solution of phenol / tetrachlorethylene 60:40 at 25 C) between 0.6 and 2.0, preferably between 0.9-1> 0 and 1.4- 1.6 have.

One can also use polyesters with lower reduced specific Go out of viscosity and through post-condensation the desired higher viscosity during the mixing process bring about.

Aliphatic polyethers are understood to mean I-olym-Te, the following recurrence; ennden the circular units:

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K ₁ it

I I

Cf-

" ^(CH 2 ⁾ α" ⁰ !

R ₂

where R ₁ to R. are hydrogen atoms or alkyl radicals with 1 to 6 carbon atoms or phenyl radicals and η is an integer of

0 to 2 mean. Homopolymers are particularly suitable of ethylene oxide, propylene oxide, styrene oxide, 3,3'-dimethyl

- oxetane and tetrahydrofuran. Copolymers of the invention cyclic ethers, e.g. copolymers of ethylene oxide with propylene oxide, can advantageously be used.

The polyethers can have molecular weights between 5000 and

Own 1,000,000. It is advantageous to use polyethers in the molecular weight range between 10,000 and 500,000 and completely especially between 10,000 and 100,000.

The amount of polyether to be mixed in depends on the desired properties of the polymer mixture and is expedient 0.1 to 2.5, preferably 0.5 to 10 percent by weight.

The addition of polyethers to polyester can be different Manner, preferably according to a) and b): ·. ■

a) The polyester is melted and optionally in the Melt was post-condensed in vacuo to the desired viscosity. Then the polyether is added and introduced intensively, ζ awake under nitrogen. If necessary, the

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The melt was stirred in vacuo until a homogeneous mixture occurred is.

b) The polyester granulate or polyester powder is mixed as evenly as possible with the polyether, melted in the extruder, Squeezed out with cooling and granulated.

c) The polyester granulate is at elevated temperature with the Roll molten polyether in a rotating jar and allow to cool with continued rolling. The mixture takes place during the processing of the .Polyester molding compositions to form the molded body ^ by the screw of the injection molding machine.

d) The polyester is melted together with the polyether, expediently under nitrogen. After melting, the mixture is vigorously stirred, if necessary under vacuum.

e) The polyester granulate is mixed with a solution of the polyether, for example rolled in benzene or toluene in a rotating vessel. The solvent is evaporated under rollers, the polyester granulate is coated with a film of the polyether. The mixture takes place when processing the polyester mold mass to the molding through the screw of the injection molding machine.

The polyester molding compound should contain as little moisture as possible, preferably less than 0.01 percent by weight.

For keeping down the absorption of moisture, the granulated

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Polyester molding compound with a coating of an inert hydrophobic Fabric such as paraffin or wax can be provided. ,

The polymer blends of the invention are thermoplastic -process to dimensionally stable moldings, which unexpectedly have a significantly increased impact strength, at the same time hardness and, abrasion resistance

keep staying. I ₁

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To obtain crystalline or semi-crystalline moldings, the mold temperature must be above the freezing temperature of the polyester material used. The moldings obtained from the polyester molding compositions produced according to the invention have good surface hardness and good surface hardness Solvent resistance and low moisture absorption due to particularly high impact strength and flexural strength speed aas. =

The polymer mixtures according to the invention can also be used Process into hollow bodies using known methods.

Example 1i

950 g of a polyester made from tetraphthalic acid and ethylene glycol with a 1? _re ^ value of 1.40 dl / g (measured on a 1 percent solution in phenal / tetrachloroethane 60:40 at 25 ° C) are mixed with 50 g of polyethylene oxide with an average molecular weight of 10,000 in a straight extruder -

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sized and then granulated,

These granules were rolled under nitrogen with 2 * 0 g of aluminum silicate powder (47 1 ° SiO ₂ , 38 "/ * Al ₂ O ₅ ; particle diameter below 2 / u) for 2 hours. Then 3.0 g of paraffin (Trorfpunkt Mj ⁰ C) rolled at 90 ⁰ C. that · material love inject 60 χ 60 χ 1 mm, which had a good dimensional stability at a mold temperature of 15O ⁰ C plates with dimensions. the impact strength of the plates was duch ft a drop test GAPR. The test plates were subjected to an impact load in such a way that a falling body, sliding on low-friction rails, was dropped from various heights perpendicularly onto the plates stretched on a frame. The tip of the drop hammer was a hemisphere with a radius r = 10 mm of the falling hammer is 500 g. The height of fall F ₂ Q was used as a measure of the impact strength, that is the height at which the impact energy was sufficient to cause the panels to break at 20% f your. 10 panels were tested per height. The results are shown in Table 1.

Example 2i

90Q g of d-3 polyester from Example 1 were mixed with 100 g of polyethylene oxide mixed with an average molecular weight of 20,000, b-weighed in an extruder and then granulated. This granulate is as described in Example 1 with AIu-

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minium silicate powder and paraffin added and to plates splashed. The result of the drop test is shown in Table 1.

Example 3:

975 g of the polyester from Example 1 was charged with 25 g of a copolymer of 20 wt .- Äthxlenoxid with? 6 propylene oxide (1 / _d in benzene at 25 ⁰ C = 2:53 dl / g), homogenized in an extruder and then granulated. As described in Example 1, these granules are mixed with aluminum silicate powder and paraffin and sprayed to form plates. The result of the drop test is shown in Table 1.

Example 4:

950 g of the polyester from Example 1 in a solution of 50 g PoIytetrahydrofuran (average molecular weight 55 000) in 100 ml. Of dry benzene iiispergiert with stirring while the solvent removed in vacuo at 50 ⁰ C. When most of the benzene has evaporated, 2.0 g of aluminum silicate powder are added and the mixture is again stirred in vacuo for 2 hours. This mixture is then sprayed to form sheets; the homogeneous mixing in of the polytetrahydrofuran takes place during the injection process through the screw of the injection molding machine. The result of the drop test is shown incorrectly in Table 1.

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Table 1: Impact strength of a mixture of polyethers with Polyethylene terephthalate

Polyether set amount IPall height F ₂₀ '
,cm Polyester
example 1 50 Polyethylene
oxide (example 1) 5 * 0 100 Polyethylene
oxide (Bei'ep.2) 10.0. 125 Ethylene oxide /
Propylene oxide
Co-polymer
(Example 3) 2.5 150 Polytetrahydrofuran
(Example 4} 5.0 115

*) Height sufficient ^{to break 20 c} / o of the panels.

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Claims (1)

Claim; Thermoplastic molding compounds, characterized in that she from a) 99.9 to 75 percent by weight of a linear saturated polyester aromatic dicarboxylic acids and, if appropriate, small amounts of aliphatic dicarboxylic acids with saturated aliphatic ones or cycloaliphatic diols, and b) 0.1 to 25 percent by weight of an aliphatic polyether exist. 1098 15/2117 BAD