Compositions: coating or plastic – Coating or plastic compositions – Silicon containing other than solely as silicon dioxide or...
Reexamination Certificate
1997-11-21
2001-12-18
Moore, Margaret G. (Department: 1712)
Compositions: coating or plastic
Coating or plastic compositions
Silicon containing other than solely as silicon dioxide or...
C106S287160, C030S032000, C528S026000, C427S387000, C428S447000
Reexamination Certificate
active
06331206
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a lacquer composition, obtainable by a treatment of an organosilane compound with water, which organosilane compound comprises at least two hydrolytically-condensable silane substituents, as well as a non-hydrolyzable silane substituent which contains a hydroxy or hydrolyzable group bonded to a carbon atom. The invention also relates to a method of applying a coating of lacquer to a substrate, in particular parts of a shaver, such as a shaver head or a housing.
A lacquer composition of the type mentioned in the opening paragraph is known from a publication by K. Greiwe in Farbe+Lack, 97(11), 1991, pp. 968-971. The known lacquer composition is obtained by treating a mixture of 3-glycidyl-oxypropyltrimethoxysilane (abbr. GLYMO), an alkyl trimethoxysilane, and aluminum tri-sec-butylate with water and a solvent. The resultant lacquer composition is used, inter alia, in a method in which the lacquer composition is sprayed onto a brass surface and cured at 130° C. for 45 minutes. A disadvantage of the known lacquer composition is that it is prepared by means of aluminum tri-sec-butylate as the catalyst. This aluminum compound, which serves as a curing agent for the polymerization of the epoxy group present in GLYMO, has a limited shelf life under ambient conditions. If the curing agent has been in contact with air, the water present in the curing agent causes the effectiveness of the curing agent to be reduced, resulting in lacquer coatings of a non-uniform quality. Storage and handling should take place under water-free conditions, which, from a practical point of view, renders the processing unattractive. Although the aluminum compound plays an essential role in curing the lacquer coating, it has no important function in the cured lacquer coating. Besides, the reactivity of the aluminum compound is such that the treatment with water has to be carried out step by step, while cooling, which renders the preparation of the lacquer composition time-consuming and laborious. For example, the preparation of said lacquer composition on an industrial scale requires a computer-controlled system comprising a cooling unit and a double-walled reaction vessel, with the dosing rate of the starting substances having to be controlled by measuring the temperature of the reaction vessel.
It is known that the reactivity and the water-sensitivity of the aluminum compound can be slightly reduced by replacing a butylate ligand by an ethyl acetoacetate ligand. However, this measure proves to be insufficient to overcome the above-mentioned drawbacks.
SUMMARY OF THE INVENTION
It is an object of the invention to provide, inter alia, a lacquer composition which does not have the above-mentioned drawbacks. The invention particularly aims at providing a lacquer composition whose catalyst exhibits such insensitivity to water that storage and handling can take place in air without the properties of the lacquer composition being adversely affected. It should also be possible to prepare the lacquer composition in a simple manner, in a single step and in a short period of time without cooling, so that the preparation of the lacquer composition on an industrial scale can be carried out by means of a simple system. The invention further aims at providing a method of applying a lacquer coating to a substrate.
The object of the invention is achieved by a lacquer composition of the type mentioned in the opening paragraph, which is characterized, in accordance with the invention, in that the treatment with water takes place in the presence of a polycarboxylic acid, which is stable in contact with water.
By using a polycarboxylic acid as the catalyst, a lacquer composition is obtained whose catalyst exhibits a long shelf life under ambient conditions. Measures enabling storage and handling under water-free conditions can be dispensed with. In addition, the catalytic activity of the polycarboxylic acid proves to be such that the lacquer composition can be obtained by bringing all starting materials including the polycarboxylic acid in contact with each other, in a single step without cooling. By virtue thereof, the preparation of the lacquer composition on an industrial scale can be carried out in a simple manner without the necessity of a complicated, computer-controlled system and process. Moreover, the lacquer composition in accordance with the invention can be obtained in a short period of time. The preparation time typically amounts to approximately ten minutes.
The polycarboxylic acid does not only serve as a catalyst for the hydrolysis of the hydrolyzable substituents and groups, but also forms, in combination with the hydroxy or hydrolyzable group of the non-hydrolytically condensable silane substituent bonded to a carbon atom, an essential constituent of the lacquer coating obtained by curing the lacquer composition in accordance with the invention. If the carboxylic acid used is a polycarboxylic acid, then it becomes part of a network connection between crosslinks of the network due to the formation of ester groups from hydroxy groups and carboxy groups. An advantage of ester groups over other condensed groups, such as amides, is that esters are formed already at a low temperature of the order of 100° C.
The advantages offered by the lacquer composition in accordance with the invention only exist if the polycarboxylic acid is stable in contact with water, the protolysis of the carboxy groups of the polycarboxylic acid of course being left aside, as this reaction is reversible and does not have any influence on the stability of the carboxylic acid. In practice, this prerequisite hardly constitutes a limitation since carboxylic acids generally are stable in contact with water. However, this prerequisite does impose limitations if the carboxylic acid comprises other substituents which, in the presence of carboxy groups, are not stable in contact with water. Examples of such water-sensitive carboxylic acids, which, therefore, are not carboxylic acids in accordance with the invention, are disclosed in U.S. Pat. No. 5,036,145, formulas 5″ and 5′″.
The lacquer composition in accordance with the invention has excellent film-forming properties and, if necessary by adding diluting agents, is excellently sprayable to form lacquer coatings. The pot life of the lacquer composition is amply sufficient and typically amounts to approximately one day. In addition, said lacquer composition puts little pressure on the environment. Only emission of alcohols and water take place.
Lacquer coatings obtained by curing the lacquer composition in accordance with the invention prove to be wear-resistant and scratch-resistant, even in the case of prolonged exposure to solvents or compositions for personal care, such as shaving lotions. The lacquer coatings are transparent and meet high quality standards from an optical and esthetical point of view.
A cured lacquer coating comprises a network in which the network connections or the connections between crosslinks at some occasions of an organic and at other occasions of an inorganic character. Therefore, such a lacquer coating is also referred to as a hybrid or composite lacquer coating. Other designations are a lacquer coating obtained in accordance with a sol-gel process or a heteropolysiloxane.
Suitable polycarboxylic acids are, inter alia, maleic acid, fumaric acid, malonic acid, oxalic acid, adipic acid, tartaric acid, pyromellitic acid, terephthalic acid. Preferably, use is made of polycarboxylic acids which can be dissolved in an alcohol, such as maleic acid, oxalic acid, a benzene tricarboxylic acid and pyromellitic acid. If, in the preparation of the lacquer composition, an alcohol is liberated as a result of the hydrolysis operation, preference should be given to polycarboxylic acids which can be dissolved in this alcohol. Particularly suitable carboxylic acids are also soluble in water, such as maleic acid and oxalic acid. Preferably, use is made of maleic acid. If necessary, the polycarboxylic acid can be
Wielstra Ytsen
Winkel Jolanda H. S.
Bartlett Ernestine C.
Moore Margaret G.
U.S. Philips Corporation
LandOfFree
Lacquer composition does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Lacquer composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Lacquer composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2584409