NZ334964A

NZ334964A - Polyol-based lubricant coolant based upon non-ionic emulsifiers and water and their use in cutting elastomers

Info

Publication number: NZ334964A
Application number: NZ334964A
Authority: NZ
Inventors: Horst Beck
Original assignee: Henkel Teroson Gmbh
Priority date: 1996-10-01
Filing date: 1997-09-22
Publication date: 2001-04-27
Also published as: JP2001503084A; ATE241686T1; DE59710181D1; TR199900583T2; CZ115199A3; KR20000048565A; PL332505A1; WO1998014539A1; DE19640489A1; AU4556097A; HUP0000048A3; HUP0000048A2; EP0931128B1; EP0931128A1; AU719234B2; ZA978763B; CA2267865A1

Abstract

Described are lubricating coolants. The coolants are based on polyols (preferably, PEG's or propylene glycols or copolymers) and non-ionic emulsifiers and water. The coolants are suitable for lubricating/cooling during the cutting of elastomers. Their use prevents overheating of the cut elastomers and of the cutting tool. Furthermore, the resultant cut surface is suitable for further bonding, without requiring any further pre-treatment, in particular when high tensile strength or combined tension and shear resistance are required for the further bonding process, such as in the direct fitting of motor vehicle windows, for example.

Description

<div class="application article clearfix" id="description"> WO 98/14539 PCT/EP97/05185 A Lubricant Based on Polyols and its Use in the Cutting of Elastomers This invention relates to a lubricant based on aqueous solutions and/or emulsions of polyols and to its use in the cutting of cured elastomers. The cutting of elastomers with various tools always involves difficulties on account of the rubber-elastic behavior of these polymeric compositions. In modern automotive construction, fixed glass is now directly bonded to the bodywork; -<-An elastomeric adhesive/sealant, in most cases based on polyurethane elastomers, is generally used for this purpose. For repair purposes, the directly bonded glass has to be cut out from the frame using various tools. Various methods are available for this purpose, including for example cutting wire, knives and electrical or pneumatic oscillating or vibrating knives. Such knives are described, for example, in DE-A-38 38 044. Where vibrating knives are used, so much heat of friction is generated that decomposition reactions occur after only a very short cutting time, as immediately reflected in the emission of smoke. This generation of heat is problematical both on hygiene grounds and on technical grounds. The hygiene-related or physiological problems are attributable to the emission of smoke gases of which the exact chemical composition is rarely known because it depends both on the composition of the elastomer and on the acutely prevailing decomposition temperature. Because the processor generally has his head relatively close to the point of smoke or gas emission, the fumes are almost inevitably inhaled. There are generally no safety measures to prevent this and, even where such measures do exist, they are difficult to put into practice. The technical problems are attributable to the fact that the knife is difficult to guide under these conditions and also to the fact that the knives easily become red hot. As a result of this intensive heating, the knives have very short useful lives. In addition, the intensive heating of the elastomer in WO 98/14539 2 PCT/EP97/05185 the cutting zone can lead to serious chemical degradation of the polymer with the result that both the chemical and the physico-mechanical characteristics of the elastomer are seriously affected. The resulting change leads to significant problems in regard to re-bonding behaviour. 5 In practice, several hitherto unsatisfactory approaches have been adopted with a view to solving the problems explained above: - Cooling of the cutting zone with solvents, particularly benzines. This method is unsuitable for physiological reasons alone. Besides the 10 health-related problems caused by exposure of the processor to solvent vapors, there is also a persistent risk of explosions here on account of the solvent vapor/air mixtures formed. These mixtures can be ignited both by hot parts of cutting tools and by electrical sparks from electrically operated cutting tools. 15 - The cutting zone cannot be cooled/lubricated with water. - Cooling of the cutting zone while the processor waits. In this case, a short section is cut until smoke is emitted, after which the blade is cooled. This method is very time-consuming and is hardly used for this reason alone. 20 - One supplier of cutting tools not only recommends, but actually stipulates the use of a baby shampoo to reduce friction in the cutting zone. To this end, a solution of this shampoo in water is sprayed onto the strand of adhesive before cutting. Around 150 to 200 ml of this detergent solution are required for spraying the adhesive strand of a 25 car windscreen. Although this method prevents the generation of heat in the cutting zone of the adhesive strand, it has a very adverse effect on the re-bonding behaviour of the remaining strand because residues of detergent are inevitably left on the cut surface. 30 In every case where the cut surface of the elastomer is involved in a WO 98/14539 3 PCT/EP97/05185 rebonding process, the last of the above-mentioned methods cannot be applied because the holding strength of the adhesive after rebonding falls to very low levels on account of the residues remaining on the cut surface. US-A-4,128,452 describes a knife for separating materials joined by an adhesive, more particularly self-adhesive labels. The blade of this knife is accommodated in a sheath with an inner lining of an absorbent material. A liquid lubricant, for example silicone oil, is uniformly distributed over the absorbent material of the sheath. When the knife is inserted into or removed from the sheath, a thin film of lubricant is distributed over all the surfaces of the blade. This provides for almost frictionless contact between the knife and the material to be separated. The liquid lubricant is supposed to prevent the adhesive cut through from becoming tacky. Accordingly, the problem addressed by the present invention was to provide a lubricant and coolant which would enable elastomers to be cut without much heat of friction being generated. The cut surfaces thus produced would remain suitable for rebonding of the elastomer parts. This is particularly important for the repair of directly bonded car glass because, when damaged glass is replaced, a so-called "residual strand", i.e. an adhesive layer of variable thickness, remains on the bodywork. Subsequently, either the adhesive for the replacement glass is directly applied to this cut surface or the cut surface acts as a contact surface for the adhesive applied to the new glass. Since bonded-in-place glass, more particularly in the form of windscreens and rear windows, is an integral part of the strength and stiffness of a car body, car manufacturers specify minimum tensile shear strengths for such bonds of, generally, at least 3 N/mm2. Standard adhesives generally achieve bond strengths of more than 5 N/mm2. Accordingly, the same strength levels also have to be reached in the event of rebonding. It has now been found that all the disadvantages of known methods can be avoided by using lubricants based on aqueous solutions and/or emulsions of polyols. This method enables car glass to be quickly and safely WO 98/14539 4 PCT/EP97/05185 rebonded and is toxically and physiologically safe. The lubricating effect of the polyol and the cooling of the blade by the water present are both very good and have been proven by numerous internal practical tests. The residual strand is re-bondable, at least 85% of the tensile shear strength determined by the adhesive always being achieved. The first-time bonding values specified by all car manufacturers are thus achieved. In principle, numerous polyols may be used for the lubricants according to the invention. Polyether polyols based on linear or branched polyethylene glycols, polypropylene glycols or copolymers thereof are particularly preferred. The molecular weight and the OH value and viscosity of the polyether polyols may vary within wide limits. Preferred ranges for the OH value are 500 to 15 mg KOH/g, OH values of 50 to 20 mg KOH/g being more particularly preferred. The viscosity of such polyether polyols at 25°C is between 500 mPa-s and 3,000 mPa-s. The OH value is determined in accordance with DIN 53240 while viscosity is determined in accordance with DIN 51550. Although polyether polyols are the preferred polyols for the purposes of the invention, polytetrahydrofurans, polyester polyols, hydroxyfunctional polybutadienes and ethoxylation and propoxylation products thereof and other water-miscible or water-emulsifiable polyols may also be used. Mixtures of high molecular weight and low molecular weight polyols and relatively small additions of surfactants or emulsifiers may be used to support miscibility with water and to guarantee a stable emulsion. Nonionic surfactants preferably containing at least 2 OH groups per molecule are generally used either individually or in the form of mixtures. The alkyl polyglycosides produced and marketed, for example, by Henkel KGaA are most particularly preferred. Preservatives known per se may be added to the lubricant according to the invention to increase its stability in storage. For the actual use as a lubricant/coolant, it is sufficient for about 2% by weight of polyether polyol to be present in the solution sprayed onto the strand of adhesive or elastomer to be cut. However, for more effective WO 98/14539 5 PCT/EP97/05185 transportation from the point of production to the point of use and in the interests of better storage, it is advisable initially to prepare a concentrate which the end user may readily dilute with water. Accordingly, a typical composition according to the invention for the 5 lubricant/coolant concentrate contains - 15 to 40% by weight of polyether polyol optionally consisting of a mixture of several polyether polyols, - 0.1 to 3% by weight of nonionic surfactants, preferably alkyl polygly-cosides, 10 - 0.05 to 0 5% by weight of preservative and - 56.5 to 84.85% by weight of demineralized water. The ratio in which such a concentrate is diluted for application is determined by its polyether polyol content and is of the order of 1:8 to 1:20. A particularly preferred embodiment of the invention is described in the 15 following. Example 1 A lubricant concentrate was prepared from the following ingredients: 29% by weight of polyether polyol (Lupranol 2040, a product of BASF, 20 hydroxyl value ca. 28 mg KOH/g), 0.8% by weight of alkyl polyglycoside (Henkel KGaA), 0.2% by weight of Acticid SPX (Thorchemie) and 70% by weight of demineralized water. The polyol and the surfactant were introduced first and water was slowly added with intensive stirring using a dissolver. It is particularly important to achieve intensive mixing in the highly viscous 25 phase to ensure that a stable emulsion containing finely dispersed polyol droplets is formed. Example 2 In a practical test, the lubricant of Example 1 was diluted with water in 30 a ratio of 1:15 for application and the resulting liquid was sprayed onto the WO 98/14539 6 PCT/EP97/05185 adhesive strand of a glazed-in car windscreen. The cured adhesive strand could be cut with a commercial vibrating knife without any generation of heat. Example 3, Comparison Example 5 To determine tensile shear strength after rebonding, glass strips measuring 25x100x4 mm and lacquered steel strips measuring 25x100x1 mm were pretreated with a primer and bonded with an adhesive strand consisting of the one-component moisture-curing direct glazing adhesive Terostat 8597 (Teroson) so that a layer thickness of 5 mm was formed. The test specimens 10 were produced and their tensile shear strength was determined in accordance with DIN EN 1465. After final curing as directed by the manufacturer, a bond such as this (referred in the standard as an original bond) develops a tensile shear strength of 5 to 6 MPa. To simulate glass removal, the accessible surfaces of the cured 15 adhesive strand perpendicular to the cut surface were sprayed with the lubricant/coolant according to the invention. For comparison, a solution of a baby shampoo in water was prepared as directed by the tool manufacturer and sprayed onto the adhesive strand. The test specimens were then cut. For rebonding, new glass strips were pre-cleaned and then pretreated with 20 the primer Terostat 8510 (Teroson). A corresponding quantity of Terostat 8597 was applied to the primer surface aired as directed by the manufacturer. The metal strips from the cutting tests still carrying the residual strand which had not been pretreated any further were then used to simulate rebonding so that a layer thickness of 5 mm was again formed. 25 After the bond had reached its ultimate strength, a tensile strength of more than 5 N/mm2 was achieved with all the test specimens containing residual strands which had been cut using the lubricant/coolant according to the invention. Test specimens containing residual strands which had been cut using the baby shampoo developed tensile shear strengths of less than 30 1 N/mm2. WO 98/14539 7 PCT/EP97/05185 It can clearly be seen that, where a recommended lubricant/coolant according to the prior art is used, there is a distinct safety risk in regard to the tensile shear strength of rebonding whereas, where the lubricant/coolant according to the invention is used, tensile shear strengths well above the minimum required by car manufacturers of 3 N/mm2 are achieved in rebonding. PCT/EP97/05185 * </div>

Claims

<div class="application article clearfix printTableText" id="claims"> CLAIMS

1. The use of a composition based on aqueous solutions and/or emulsions of polyether polyols as a lubricant for lubrication and cooling in the cutting of cured elastomeric adhesive/sealant joints or of cured 5 elastomeric moldings or profiles.

2. The use claimed in claim 1, characterized in that the lubricant contains water, at least one polyether polyol, one or more nonionic surfactant(s) and optionally preservatives.

3. The use claimed in at least one of the preceding claims, 10 characterized in that the polyether polyol is selected from the group consisting of linear or branched polyethylene glycols, polypropylene glycols or copolymers thereof.

4. The use claimed in claim 3, characterized in that the polyol has an OH value of 500 to 15 mg KOH/g (DIN 53240) and preferably 50 to 20 mg 15 KOH/g and a viscosity at 25°C of 500 mPa-s to 3,000 mPa-s (DIN 51550).

5. The use claimed in any of claims 2 to 4, characterized in that the surfactant(s) contain(s) at least 2 OH groups.

6. The use claimed in claim 5, characterized in that the surfactant(s) is/are an alkyl polyglycoside. 20

7. A process for cutting cured elastomeric adhesive/sealant joints or elastomeric moldings, characterized by the following steps: - spraying or coating of the areas of the elastomer to be cut with the lubricant claimed in claims 1 to 6, - cutting of the elastomer with a vibrating or oscillating knife or a cutting 25 wire, - optionally flexible rebonding on at least one of the cut surfaces. AMENDED SHEET END </div>