WO1994002301A1

WO1994002301A1 - Use of ethers as mould release agents for thermoplastic polyesters

Info

Publication number: WO1994002301A1
Application number: PCT/EP1993/001753
Authority: WO
Inventors: Rainer HÖFER; Dieter Krampitz; Andreas Lippmann; Fritz Lange
Original assignee: Henkel Kommanditgesellschaft Auf Aktien
Priority date: 1992-07-15
Filing date: 1993-07-07
Publication date: 1994-02-03
Also published as: DE4223275A1

Abstract

The invention concerns the use of monohydric or polyhydric alcohols as mould release agents for thermoplastic polyesters, as well as a method of producing thermoplastic polyester moulding compounds in the presence of ethers.

Description

"Use of ethers as mold release agents for thermoplastic polyesters"

The invention relates to the processing of thermoplastic polyesters and relates to the use of ethers of monofunctional or polyfunctional alcohols as mold release agents for thermoplastic polyester compositions and a process for the preparation of thermoplastic polyester compositions in the presence of ethers.

Linear polyesters are obtained by esterifying diols with dicarboxylic acids or derivatives thereof. High molecular weight, linear, aromatic / aliphatic polyesters are high-melting products, the most important representative of which, polyethylene terephthalate, plays an important role in the fiber and film field. Although these products have been known as fiber raw materials since 1941 (see H. Sattler, "Chemical fibers", in Winnacker, Küchler, "Chemical technology", 4th edition, Volume 6, Organic Technology II, Carl Hanser Verlag , Munich, 1982), it was only in the mid-1960s that these products could be converted into molded articles with valuable properties by thermoplastic processing methods (cf. KD Asmus, d. Niedenberg, H. Schell, "Kunststoffe" 59, 266 (1969 ), and R. Pflüger, "Kunststoffe" 57, 31 (1967)). The prerequisite for these processes is compliance with defined processing conditions and frequently the use of so-called nucleating agents in order to accelerate the crystallization and to produce an optimal crystallite size in the shaped bodies. Among the thermoplastic polyesters, polyethylene terephthalate (PETP) and polybutylene terephthalate (PBTP) have so far become very important; they are very hard, stiff, wear-resistant and dimensionally stable. Furthermore, they have good solvent resistance and weathering stability as well as excellent electrical properties. Although the semi-crystalline products are more important in terms of application technology, copolyesters made from terephthalic acid or from isophthalic acids and bifunctional alcohols, eg. B. 1,4-dimethylolcyclohexane and neopentyl glycol, because of the lack of tendency to crystallize and the transparency gained thereby, an increasing importance, especially as (co) -extruded films with excellent barrier properties in the packaging sector for blister packs, protective films, thermoformed containers and assortment boxes for food, furthermore also in injection molding for toys, apparatus parts, display articles and the like, cf. Eastman Plastics, Publications No.MB-82B, TR-61C, PTP-25B.

Known mold release agents for injection molding processing of thermoplastic polyalkylene terephthalates are paraffin waxes, polyethylene waxes or oxidized polyethylenes produced by air oxidation of "high-density" or "low-density" polyethylene, which are described, for example, in EP-B-262566 as mold release agents for polycarbonate / Polyalkylene terephthalate blends are described. However, these products have the disadvantage that they lead to severe clouding and their use in transparent articles is prohibited.

DE-A-19 21 010 describes esters of long-chain, organic acids with 1- to 10-valent alcohols, e.g. B. pentaerythritol tetrastearate or methyl stearate alone or in combination with natriu stearate, to improve the processing properties of thermoplastic polyesters. These compounds are suitable for improving the surface properties of the polyesters and, as external lubricants, for easy removal of the poly to promote ester moldings from the molds. Certain fatty alcohols and fatty acid esters of polyhydric alcohols alone or in combination with fatty acid soaps of bivalent metal ions are known to improve the ability to unstack deep-drawn plastic articles, such as assortment boxes, as mold release agents.

The invention is aimed at providing new mold release agents for thermoplastic polyesters which are suitable for improving the slip behavior and / or the transparency of thermoplastic polyester molding compositions, in particular of co-polyester films, such as PETG polyester films. Such films are often so smooth and pliable that they can be on machine surfaces or, for. B. stacked on top of one another as a bag or as a deep-drawn molded article, strongly adhere to one another. They can then no longer be lifted off one another or opened and disrupt or prevent the containers from being filled and transported on packaging lines. Surprisingly, certain ether compounds can overcome this disadvantageous slip behavior of the polyester films.

The present invention accordingly relates to the use of ethers selected from the group of the monoethers of monofunctional alcohols with 10 to 32 carbon atoms and polyethers of polyols with 2 to 6 hydroxyl groups which are wholly or partly with monofunctional alcohols 1 to 32 carbon atoms are etherified as mold release agents for thermoplastic polyester compositions.

The ethers used according to the invention are known compounds which can be prepared from the alcohols by acidic etherification or, after the Williamsen ether synthesis, by nucleophilic substitution on alkyl halides, sulfates and sulfonates with alcohols. The monoethers are those derived from monofunctional aliphatic alcohols with 10 to 32 carbon atoms. In principle, the monoethers can be derived from the same monofunctional alcohols, resulting in symmetrical monoethers, or also from different monofunctional alcohols, resulting in asymmetrical monoethers. The monoethers used according to the invention are preferably derived from monofunctional aliphatic, preferably from monofunctional aliphatic, saturated alcohols and in particular with 12 to 22 carbon atoms. Examples of suitable monoethers are decyl dodecyl ether, didodecyl ether, tallow stearyl ether, ditallow, distearyl ether, tallow behenyl ether and dibehenyl ether.

In the present invention, the term “polyether” is understood to mean ethers of polyols having 2 to 6 hydroxyl groups, which are completely or partially etherified with monofunctional alcohols. Accordingly, the polyethers have at least one ether group and at most 6 ether groups per polyether. Possible polyol components are both diols with 2 to 22 carbon atoms and other polyols with 3 to 6 hydroxyl groups, such as glycerol, triethylolpropane, pentaerythritol and / or dipentaerythritol. These polyols are etherified with monofunctional alcohols having 1 to 32 carbon atoms, the monofunctional alcohols being able to be both those which have already been described for the monoethers and lower monofunctional alcohols such as methanol, ethanol, propanol, i- and n-buta - nol, i- and n-hexanol, i- and n-heptanol and octanol. A preferred group of the polyethers are ethers of diols such as ethylene glycol, propylene glycol, hexanediol, octanediol, decanediol, dodecanediol, hexadecanediol and / or octadecanediol. The diols are preferably completely etherified with monofunctional alcohols, preferably with monofunctional aliphatic alcohols and in particular with monofunctional aliphatic saturated alcohols having 12 to 22 carbon atoms of the type already described. The diethers of ethylene glycol, such as dilaurylethylene glycol ether and dipalmitylethylene glycol ether, are particularly preferably used here.

Another preferred group of polyethers relates to partial ethers of glycerol, triethylolpropane, pentaerythritol and / or dipentaerythritol with monofunctional aliphatic alcohols, preferably monofunctional aliphatic saturated alcohols with 12 to 22 carbon atoms, the partial ethers having at least one free one Wear hydroxyl group. Particularly preferred representatives of such partial ethers are the glycerol monoethers of tallow alcohol, lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol and behenyl alcohol. Of the trimethylol propane ethers, the trimethylol propane diethers of tri ethylol propane coconut ether are preferred.

For the purposes of the invention, the monoethers and the polyethers can be used both alone and in any combination with one another. Mono- and / or polyethers which are present at room temperature at least as a pasty mass, preferably as a solid, are particularly preferred.

In order to be effective as a mold release agent for thermoplastic polyester compositions in the sense of the invention, it is advisable to add the ethers in amounts of 0.01 to 3, in particular 0.1 to 2,% by weight, based on polyester weight use. The slip behavior of thermoplastic polyester molding compositions, preferably of polyethylene terephthalates, and in particular of their films, can be improved by using the polyethers. In addition, most of the ethers used in accordance with the invention, and in particular the polyethers of glycerol, which are partially etherified with monofunctional aliphatic saturated alcohols having 12 to 22 carbon atoms, show extremely good transparency. They are therefore particularly suitable for clear, transparent polyester molding compositions and in particular for polyethylene terephthalate films. Another object of the present invention is a process for the production of thermoplastic polyester molding compositions, in particular polyester films based on polyalkylene terephthalates, which is characterized in that the polyester compositions are mixed with ethers selected from the group of monoethers and polyethers. The polyethers are mixed in in a manner known per se. For example, ethers which have melting points below 90 ° C. are applied in a customary manner to the polyester compositions using a mixer, preferably using a fluid mixer. Ethers which have higher melting points are mixed into the polyester materials by tumbling. Further details on the method can be found in the above description.

B e i s p i e l e

A) Preparation of the ethers

Example 1: Glycerol monoether from tallow alcohol

3315 g of glycerol, corresponding to 36 moles, were heated to 150 ° C. together with 240 g of 50% strength by weight sodium hydroxide solution under nitrogen. 1029 g of sodium salt of a tallow alcohol sulfate, corresponding to 3 mol, (tallow alcohol, composition in% by weight: 25-30 CJÖ? 65-70 C ^ g; balance Ci2-14 and C20) were added and 10 hours at 180 ° C implemented.

The reaction mixture was washed with 1.5 l of n-hexanol and twice with 1.5 l of water. a white solid product with a hydroxyl number OHZ (according to DIN

53240) = 296.

Example 2: Glycerol monoether of (2 / (alcohol

45 kg of glycerol, corresponding to 4887 mol, 7.2 kg of 50% by weight sodium hydroxide solution and 26.1 kg of sodium salt of a Cχ2 / Ci4 alcohol sulfate, corresponding to 90 mol, (alcohol, composition in% by weight) %: 65 - 75 C12, 22 - 30 C14, balance C10, Ciö-lβ) reacted with each other. The reaction mixture was washed twice with 20 kg of water, separated and dried. A white solid product with an OHN of 366 was obtained.

Example 3: Tallow stearyl ether

28.4 kg of stearyl alcohol (with> 95% by weight of cis), corresponding to 105 mol, and 18.9 kg of 30% by weight sodium methoxide solution were heated to 150 ° C. under nitrogen. A total of 36 kg of sodium salt of a tallow alcohol sulfate according to Example 1, corresponding to 105 mol, were added in portions and heated to 180 ° C. for 8 hours. The reaction mixture was with 2x 20 kg of water and 41.5 kg of hexanol washed and dried. A solid product with an OHZ of 37.5 was obtained.

B) application

Production of mixtures of polyesters and ethers to be used according to the invention

A polyester commercially available product from Eastman Chemical Products, Inc., Kingsport, Tennessee, USA (K0DAR ^R PETG copolyester 6763) was used, which is a crystal-clear amorphous polymer with a glass transition temperature of about 81 ° C. and a number average molecular weight of is about 26,000.

The ethers to be used according to the invention, insofar as they had melt products of less than 90 ° C., were applied to the granulated PETG polyester in a Henschel fluid mixer at low speed (approx. 1000 rpm) and temperatures of approx. 80 ° C. The mixture was removed from the mixer in the hot state. In products with higher melting ranges, the distribution of the ethers was achieved by tumbling in a polyethylene bag.

This was followed by homogeneous incorporation of the ethers in a Collin twin-shaft kneader, type 235 (50 X 15 D) with a K-Tron T 20 twin screw and integrated water cooling bath and round strand pelletizer. The extrusion temperatures were between 230 and 235 ° C, the screw speed at 70 rpm. The granules obtained were dried at 75 ° C. for at least 8 hours.

C. Testing the polyester / ether mixtures

1. Slip effect

To determine the slip effect, a test according to DIN 53375 (determination of the friction behavior) was carried out. The slides required for this were manufactured with a Brabender film blowing system, consisting of a Plasticorder PLE 651, extrusiograph (30 x 25 D) and a blow head (nozzle diameter 50 mm) as well as a take-off system with air control box, roller assembly and automatic width adjustment device.

Extrusion parameters; Cylinder temperature: 180 to 220 ° C nozzle temperature: 210 to 235 ° C screw speed: 40 U / min take-off roller speed: 6 to 7 m / min.

Test pieces of approx. 8 x 12 cm were cut out from the film tubes obtained (thickness approx. 100 mm) for the friction measurement. The inner surfaces of the film were kept at a distance by paper and then stored in a test climate (approx. 50% real air humidity and room temperature).

The friction measurements were carried out in accordance with DIN 53375-A (film against film) with the RPF friction tester with electronic force measuring device (Wazau company) immediately after production of the films and after 24 hours, 2 to 3 days and 1 week (inside measured, triple determination).

The sliding friction coefficient μn. is calculated according to μp = FQ / FN, where Fp = sliding friction force in N and FR = normal force in N.

The results are summarized in the table. If the sliding friction number is given in the table, there was consistently smooth sliding. If "-" was given, there was no improvement in the slip effect, ie in sliding. 2. Maintaining transparency

The assessment of the transparency was carried out using a measuring device from Lange (universal measuring unit UME 3 and transparency measuring head LT 12). Sprayed spirals (3 mm thick) were used as test specimens.

The spirals were produced with the Mannesmann Demag injection molding machine DNC-120.

Injection molding parameters: Cylinder equipment: open nozzle, screw diameter = 45 mm, with non-return valve

Cylinder temperatures: 230-250 ° C

Nozzle temperature: 260 ° C

Screw speed: position 16

Injection pressure: 31

Reprint: 16

Snail back pressure 4

Injection speed 4

Nozzle contact force 9

Form clamping force 1000 kN

Injection time 5.0 s

Holding time 2.0 s

Pause time 2.0 s

Cooling time 15.0 s

Dosing delay time 0.5 s

Time nozzle back 2.0 s

Dosing path 37 mm

Compression relief 39 mm

Tool spiral shape, 3 x 15 mm deflected at right angles

Mold temperature water-cooled Sprue rod

Since the spiral did not completely cover the measuring area of the LT, the area was reduced to 1.6 x 1.6 cm by a cover.

The measurement was carried out without using spectral filters. The standard setting (= light transmission) was made on the blank sample (Kodar PETG-6763, without additive).

table

Claims

Patent claims

1. Use of ethers selected from the group monoethers of mono-functional alcohols with 10 to 32 carbon atoms and polyethers of polyols with 2 to 6 hydroxyl groups, which are fully or partially etherified with monofunctional alcohols with 1 to 32 carbon atoms , as a mold release agent for thermoplastic polyester materials.

2. Use according to claim 1, characterized in that monoethers of monofunctional aliphatic alcohols, preferably of monofunctional aliphatic saturated alcohols and in particular with 12 to 22 carbon atoms, are used.

3. Use according to claim 1, characterized in that as the polyether diether of diols having 2 to 22 carbon atoms, completely with mono-functional alcohols, preferably with monofunctional aliphatic alcohols and in particular with monofunctional aliphatic saturated alcohols with 12 to 22 C atoms are etherified, are used.

4. Use according to claim 3, characterized in that the diethers of ethylene glycol are used as polyethers.

5. Use according to claim 1, characterized in that partial ethers of glycerol, trimethylolpropane, pentaerythritol and / or dipentaerythritol with monofunctional aliphatic alcohols, preferably monofunctional aliphatic saturated alcohols having 12 to 22 carbon atoms, are used as polyethers, the partial ethers being used carry at least one free hydroxyl group.

6. Use according to claim 1, characterized in that the ethers are used in amounts of 0.01 to 3, in particular 0.1 to 2 wt .-% - based on polyester weight.

7. A process for the preparation of thermoplastic polyester molding compositions, in particular polyester films based on polyalkylene terephthalates, characterized in that the polyester compositions ether selected from the group of monoethers of monofunctional alcohols having 10 to 32 carbon atoms and polyethers of polyols having 2 up to 6 hydroxyl groups which are fully or partially etherified with monofunctional alcohols having 1 to 32 carbon atoms.