Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2003-07-11
2004-09-21
Osele, Mark A. (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S272200, C156S273300, C156S275700, C156S281000, C156S331700, C510S421000, C510S433000, C510S435000, C510S436000, C510S506000
Reexamination Certificate
active
06793760
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a cleaning agent for PVC surfaces and its use, in particular for cleaning before subsequent adhesive bonding.
It is well known that surface treatment before adhesive bonding has a decisive influence on the quality of the adhesion of a subsequent coating or adhesive bond. It includes a) surface preparation by cleaning, improving the suitability and degreasing and b) surface pretreatment by mechanical, physical, chemical or electrochemical means such as corona treatment, flame treatment and the application of adhesion promoters or primers (compare Habenichts “Kleben: Grundlagen, Technologie, Anwendung” Springer-Verlag, 3
rd
edition (1997), pages 495 to 512).
Chlorinated hydrocarbons, such as methylene chloride, are used for treating the surfaces of PVC articles. However, these cleaning agents endanger the environment. To eliminate this disadvantage, it has been suggested in DE 43 43 468 to prepare PVC profiles by ionic/multi-ionic corona treatment for subsequent adhesive bonding with a PU melt adhesive followed by the application, by calendering, of a PVC film. In this way, bond strengths are achieved which are at least as good as those achieved by cleaning with chlorinated hydrocarbons.
However, both surface treatments can be improved with respect to the durability of the adhesive bond, e.g. under the influence of heat and climatic changes.
A requirement consequently existed for a surface treatment for PVC articles, in particular PVC profiles, without the use of chlorinated hydrocarbons, in order to improve the durability of the adhesion of both an adhesive bond and a coating.
SUMMARY OF THE INVENTION
The solution is indicated in the claims. It consists essentially of an aqueous alkaline cleaning agent having the following composition:
A) 2 to 30 wt. % of a compound having an alkaline reaction in an aqueous medium,
B) 1 to 30 wt. % of a complexing agent,
C) 5 to 40 wt. % of a compound with at least one hydroxyl group,
D) 1 to 15 wt. % of a surfactant based on fatty alcohols,
E) 1 to 30 wt. % of a rinsing auxiliary agent,
F) 0 to 8 wt. % of water-soluble colorants and builders,
G) 20 to 80 wt. % of water.
The percentage by weight relates to the cleaning agent as a whole. However, it is also possible to prepare a stock solution in high concentration which is then diluted, before use, to the indicated concentration by the addition of water. The quantities indicated must always add up to give 100 wt. %.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A compound having an alkaline reaction in an aqueous medium should be understood to mean both strong and weak, both volatile and fixed compounds having an alkaline reaction, i.e. hydroxides and salts of weak acids of alkali and alkaline earth metals as well as amines and ammonia. NaOH, KOH, waterglass, ammonia and amines, in particular a combination of volatile and fixed compounds, are preferred. Volatile substances having an alkaline reaction should be understood to mean substances which have a pH of >7 in aqueous solution and volatize at room temperature or slightly elevated temperatures. The ratio of volatile to fixed compounds having an alkaline reaction should be in the region of 10:1 to 1:10, preferably in the region of 2:1 to 1:2.
The concentration of the compounds having an alkaline reaction as a whole is preferably in the region of 5 to 15 wt. %.
The pH of the cleaning agent should be above 12, preferably above 13, in particular in the region of 13.5 to 14.0.
The term complexing agents should be understood to mean compounds which are capable of complexing and masking metals. These include in particular Na salts or ammonium salts of diethylenetriamine pentaacetic acid (DTPA), hydroxyethylenediaminetriacetic acid (HEDTA), propylenediaminetetraacetic acid (PPTA), ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), citric acid, alanine diacetic acid, polyaspartic acid and methylglycidine diacetic acid as well as polycarboxylates and their mixtures. The preferred complexing agents are nitrilotriacetic acid-Na and alanine diacetic acid-Na. They are available on the market under the name Trilon A and Trilon M.
Preferably, the complexing agents are used in a concentration of 2 to 10 wt. %. Of particular importance is the weight ratio of complexing agents to substances having an alkaline reaction. It should be within the region of 2:1 to 1:8.
The compound with at least on hydroxyl group is an alcohol, in particular a higher alcohol. The number of hydroxyl groups is 1 to 12, preferably maximum 2. Higher alcohols should be understood to mean alcohols with 3 to 12 C atoms in the molecule. Concrete examples are benzyl alcohol and phenoxyethanol. However, ethers of polyols also belong to the higher alcohols, e.g. propylene glycol n-butyl ether, propylene glycol methyl ether, propylene glycol isobutyl ether and propylene glycol phenyl ether. The higher alcohols also include ethers of oligopropylene glycols such as dipropylene glycol methyl ether and tripropylene glycol methyl ether as well as ethyl or methyl diglycols. The glycols include in particular butyl glycol and butyl diglycol as well as ethylene glycol. These compounds with at least one hydroxyl group are preferably used in a quantity of 15 to 25%, individually or in mixture.
The fatty alcohols for the surfactants are above all fatty alcohols with 8 to 18, in particular 12 to 18 C atoms. However, oxy alcohols with 8 to 18, in particular 9 to 13 C atoms can also be used. These fatty alcohols are reacted with hydrophilic substances. In this way, fatty alcohols with 12 to 18 C atoms, for example, are etherified with 3 to 50 ethylene oxide units and, if necessary additionally with 1 to 15 propylene oxide units. The fatty alcohol alkoxylates can be used in a form with closed terminal groups. They can also be converted to fatty alcohol ether sulphates by sulphatising or to fatty alcohol sulphonates by sulphonation.
Glucose, for example, is another hydrophilic substance. Alkyl polyglycosides, e.g. Glucopon and Plantaren as well as Intensol are preferred.
The preferred concentration of the fatty alcohol surfactants is 2 to 8 wt. %. Apart from the fatty alcohol surfactants, rinsing auxiliary agents are also used.
The rinsing auxiliary agents are substances which are intended to achieve certain effects such as a solubilising mixture. In concrete terms, rinsing auxiliary agents are, on the one hand, phosphates and, on the other hand, sulphonates of the cumene and toluene sulphonate type. Phosphoric acid esters are also suitable rinsing auxiliary agents. Such substances are usually used as surfactants or builders in rinsing auxiliary agents. In concrete terms, the following deserve to be mentioned: pentasodium triphosphate, alkyl benzene sulphonate, alkane sulphonate and/or ester sulphonate.
In general, the water concentration is in the region of 20 to 80, in particular 50 to 60 wt. %.
Apart from these essential components of the cleaning agent, substances can be added in order to satisfy certain requirements in individual cases such as colorants, perfumes, builders.
The composition according to the invention is, surprisingly, highly suitable for cleaning PVC surfaces for subsequent adhesive bonding or coating. The adhesion on the PVC surface has been shown to become more resistant to the effect of heat and climatic fluctuations. This becomes particularly clear in the case of PVC profiles. PVC profiles are widely used as solid, hollow or core profiles because they are easy to manufacture by the extrusion process and because of their low costs and satisfactory application properties. The PVC used for this purpose can be flexible, semi-flexible or rigid PVC. To improve the properties and, above all, the appearance of the profiles, their surface is treated. PVC profiles are usually used in the building and furniture industry e.g. as skirting boards, kick strips, sliding rails, curtain rails, window frames, window seal fillets, door edges, door flames, roller blinds, balcony cladding, partitioning, panelling, façade cladding, stair
Gehrke Joerg
Hoffmann Horst
Kleinert Horst
Rogmann Karl-Heinz
Carmen Michael E.
Harper Stephen D.
Henkel Kommanditgesellschaft auf Aktien
Osele Mark A.
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