GB2300865A

GB2300865A - Lubricant for covering polyurethane foam mouldings

Info

Publication number: GB2300865A
Application number: GB9609586A
Authority: GB
Inventors: Helmut Lammerting
Original assignee: TH Goldschmidt AG
Current assignee: Evonik Operations GmbH
Priority date: 1995-05-13
Filing date: 1996-05-08
Publication date: 1996-11-20
Anticipated expiration: 2016-05-08
Also published as: FR2733993B1; GB2300865B; FR2733993A1; DE19517702C1; GB9609586D0

Description

-I- Lubricant for covering polyurethane foam mouldincrs 2300865 The

invention relates to the use of high molecular weight polyethers based on polyoxypropylene as lubricant for covering polyurethane foam mouldings, in particular upholstery elements.

Elastic polyurethane foams having a bulk density of from 30 to 70 g/dM3 usually have, owing to an opencelled structure, dull surfaces which make subsequent covering with fabric difficult, considerable friction occurring. It is also found that the foam covered with fabric or leather emits squeaking noises on loading owing to the continual friction.

Previous attempts have been made to solve this problem by application of lubricants to the foam body is surface. Both silicone oil emulsions and mineral oil emulsions are available on the market for this purpose.

However, these emulsions create problems, since there is a danger of contaminating the workplace and the foam can very easily be damaged, especially since the lubricant is frequently applied in the vicinity of the foaming place.

Particularly in the production of upholstery elements in the automobile industry, there is the additional danger of soiling the covering fabrics. In addition, on handling the silicone -contaminated parts there is a danger of damaging the body paintwork.

There was therefore a need for a lubricant which is completely suited to its function and - is physiologically satisfactory and acceptable - is silicone-free and - is free of mineral oils and foam-damaging',,-.Pstances and avoids the disadvantages associated therewith.

The object of the invention is achieved by a lubricant for covering polyurethane foam mouldings, in particular upholstery elements, based on an aqueous dispersion of a lubricating oil as active substance and emulsifiers, which is characterized in that it---contains as active substance water- insoluble, liquid polyoxypropy- lene or polyoxypropylene-polyoxyethylene ethers, whose ethylene oxide content should be less than or equal to 15%, having a mean molecular weight of from 6 000 to 12 000, and has a viscosity of from 2 500 to 6 000 mPa.s. Diol ethers are preferred for the application.

Typically the aqueous dispersion comprises 35-50% of the active substance, 40-60% of water and 3-10%, preferably 3-8%, of emulsifier. All percentages quoted herein are percentages by weight.

The polyoxypropylene ethers can contain oxyethyl- ene units in blocks or randomly distributed. However, the number of these oxyethylene units has to be low enough for the conditions of water- insolubility, a liquid aggregate state and the viscosity to be met. It is is therefore not possible to give limits for the proportion of oxyethylene units, since the possible proportion depends, inter alia, on the molecular weight of the copolymer. It is generally the case that the tolerable proportion of oxyethylene units becomes greater with increasing molecular weight. The polyethers of the invention are prepared by addition of the alkylene oxides to dihydric or polyhydric initiator alcohols.

Preference is given to polyoxypropylenediol ethers which are free of oxyethylene groups. They can be prepared, for example, by adding propylene oxide to dihydric initiator alcohols in the presence of a catalyst. Examples of suitable initiator alcohols are propanediol, butanediol and hexanediol.

The preferred polyether generally consists of 100% of propylene oxide, has a molecular weight of fiom 6 000 to 12 000 and has a viscosity of from 2 500 to 6 000 mPa.s. Any proportion of ethylene oxide should be extremely low and not exceed 15%.

This high molecular weight polyether cannot be applied in the present form. Emulsions containing up to 50% of active substance can be prepared therefrom by means of nonionic emulsifiers. Preference is given to a polyether content of 35%.

Suitable emulsifiers are nonionic products such as fatty alcohol-EO adducts or addition products of ethylene oxide and fatty acids. Well suited emulsifiers are those having an EMB value of from 16 to 19, for example polyoxyethylene stearate containing from 50 to 100 units of ethylene oxide. The emulsion thus prepared has a low viscosity and can be applied satisfactorily in the present form, but also when diluted with water. For spray application, preference is given to a concentration of 10% of active substance.

The emulsion is generally used directly af ter the removal of the foam body from the mould, i.e. in the vicinity of the foaming process. Of particular importance in use is the fact that the agent of the invention contains no foam poisons or substances which destroy foam.

The demoulded foam body is generally transported further on a conveyor belt. The lubricant is applied during transport by means of air-atomizing spray guns. Application can be carried out manually or by means of automatic spray units. The amount applied is about 5 g for a foamed front seat, this means, at a prescribed application rate of 75 g/minute, a spray time of 4 seconds. For this purpose, a material pressure of 0.5 bar and an atomizer pressure of 2.0 bar are set. The diameter of the circular nozzle used is 0.5 mm. Application is generally carried out on one side on the strongly contoured seating surface.

During further transport of the moulding which is warmed by the exothermic reaction, the active substance of the lubricant dries up, so that a coherent film is formed.

The lubricant film of the invention remains on the moulding. During covering of the foam body, it fulfils the function of a lubricant and thus makes this process considerably easier. It also remains on the contact surfaces between moulding and covering fabric and gives a lasting, long-term reduction in the frictional forces, so that no squeaking noises can occur during use of the upholstery elements.

is Example 1 a) To prepare a composition containing the lubricant of the invention, a 1.5 1 stirred vessel is charged with 50 g of water and 50 g of a polyoxyethylene stearate containing 100 units of ethylene oxide. 350 9 of a polyoxypropylenediol ether (mean molecular weight of 8 000) are added in portions to this initial charge and intimately mixed using a high- shear stirrer. 550 g of dilution water is stirred in portions into this high-viscosity dispersion under low shear. This gives a stable finely divided emulsion.

To prepare a ready-to-use, sprayable composition, 30 parts by weight of the composition containing the lubricant of the invention are mixed with 70 parts by weight of water.

b) To test the composition containing the lubricant of the invention, a cold foam cushion having a size of 10 x 10 x 40 cm is foamed. A model formulation as is customarily used for producing automobile seats is employed for this purpose. This is based on a high molecular weight polyethertriol having a molecular weight of 6 000, contains the customary additives such as amine catalysts, crosslinkers, silicone stabilizers and water as blowing agent and is foamed using an isocyanate mixture consisting of 80 parts of tolylene diisocyanate and 20 parts of diphenylmethane diisocyanate. A mould-foamed bulk density of 45 g/dm' is obtained.

Immediately afterwards, the ready-to-use aqueous composition containing the lubricant of the invention is sprayed onto the demoulded moulding on all sides for 4 seconds by means of an air-atomizing spray gun having a circular nozzle of 0.5 mm diameter and a coherent film is thus produced. The material -conveying pressure is 0.5 bar and the air atomizater pressure is 2.0 bar. The throughput of the gun is 75 g/minute. The moulding sprayed with the lubricant of the invention is dried for 15 minutes to evaporate the water.

A covering fabric as is used in the automobile industry is then drawn over it. Very good lubricant action and satisfactory covering is found. The covered foam cushion is subsequently flexed. No noise emission is found.

The covered foam cushion is stored for a half year at 401C in an oven. The flexing procedure is then repeated. No noise emission is found.

Examiple 2 (without lubricant) A foam cushion is produced in a similar manner to Example 1 a) and, without a lubricant being sprayed on is beforehand, a covering fabric is drawn over it. Very high friction is found during covering and squeaking is found on flexing the covered moulding.

Comparative example (not according to the invention) a) A 10% strength aqueous solution of a water-soluble polyethertriol not according to the invention and having a mean molecular weight of 5 000, an ethylene oxide content of 16% and a propylene oxide content of 84% is tested in a manner similar to Example 1 b). After spraying on, this shows no greasing on the moulding. On covering the moulding, the desired lubricating action is not achieved. On flexing, squeaking noises can clearly be heard.

b) For comparison, a product from the prior art is tested. This is an aqueous nonionic dispersion containing 10% of active substance. This comprises a polydimethylsiloxane and paraffin wax. This emulsion is applied in a manner similar to Example 1 b) to a previously produced moulding.

Although this product of the prior art does have a lubricant action, the coated foam parts show excessive greasing so that silicone residues are transferred on handling. It is known that the automobile industry desires silicon-free auxiliaries which do not damage paint.

Claims

A lubricant suitable for application to polyurethane foam mouldings which comprises a dispersion, in water, of one or more emulsifiers and an active substance which is a water-insoluble, liquid polyoxypropylene ether or polyoxypropylene-polyoxyethylene ether having an ethylene oxide content less than or equal to 15%, a mean molecular weight of from 6 000 to 12 000 and a viscosity of from 2 500 to 6 000 mPa.s.
2. A lubricant according to Claim 1 wherein the active substance is a polyoxypropylene ether or polyoxypropylenepolyoxyethylene ether having a mean molecular weight of from 7 000 to 10 000.
3. A lubricant according to Claim 1 or 2, wherein the active substance is a diol ether.
4. A lubricant according to claim 3 wherein the active substance is a polyoxypropylene diol ether.
5. A lubricant according to any one of the preceding claims which comprises an emulsifier having a HLB value of from 16 to 19.
6. A lubricant according to any one of the preceding claims wherein the dispersion comprises 35-50% by weight of the active substance, 40-600-. by weight of water and 3-10% by weight of emulsifier.
7. A lubricant as claimed in claim 1, substantially as hereinbefore described in Example 1.
8. A ready-to-use, sprayable lubricant composition which comprises 30 parts by weight of a lubricant as claimed in claim 6 and 70 parts by weight of water.
9. A composition according to claim 8 which comprises 10% by weight of the active substance.
10. A process for decreasing friction on the surface of a polyurethane foam moulding, which process comprises applying to the moulding a lubricant as claimed in any one of claims 1 to 7, either directly or diluted in water, or a lubricant composition as claimed in claim 8 or 9.

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11. A process according to claim 10 wherein the polyurethane foam moulding is an upholstery element.
12. A coated moulding produced by applying a lubricant as claimed in any one of claims 1 to 7, either directly or diluted in water, or a lubricant composition as claimed in claim 8 or 9, to a polyurethane foam moulding.
13. A coated moulding according to claim 12 which is an upholstery element.