Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – With oxygen or halogen containing chemical bleach or oxidant...
Reexamination Certificate
2001-03-22
2001-10-30
Kopec, Mark (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
With oxygen or halogen containing chemical bleach or oxidant...
C510S109000, C510S116000, C510S511000
Reexamination Certificate
active
06310026
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of cleaning of an inorganic filler in resin-based materials, and to a method for surface treatment of the inorganic filler after cleaning. The proposed methods should be applied resin-based materials for industrial or biological use, particularly dental resin restorative materials such as dental resin composite, resin-based adhesives, cements, resin-made tooth crown prostheses, and denture base resins, in order to bind an inorganic filler firmly to a resin matrix.
2. Description of the Conventional Art
Dental resin restorative materials represented by resin composite and resin-based adhesives, cements have been widely used in dentistry. These materials are generally composed of inorganic filler particles blended into a resin matrix, as a substrate to enhance the strength of the dental resin restorative after curing. As a method for enhancing the strength of the dental resin restorative, is employed a method in which in order to bind an inorganic filler to be formulated into the dental resin restorative materials more firmly to a resin matrix, the inorganic filler is subjected to a silane coupling processing.
In the inorganic filler used for the dental resin restorative material, the strength and surface properties of the dental resin restorative after curing vary depending on the particle size thereof. Although, inorganic fillers having a particle size of from several tens &mgr;m to several hundreds &mgr;m have been used for the conventional dental resin restorative materials, in recent years, microfine inorganic fillers having a particle size of about 0.04 to 5 &mgr;m are mainly used in the dental resin restorative material, resulting in increase of a specific surface area of the inorganic filler in the dental resin restorative material.
It has been indicated that organic substances, such as carbon, which are considered to attach during the production or storage of the inorganic filler, i.e., contaminants on the inorganic filler surface, adversely affect the binding between the inorganic filler and the resin matrix strongly. These contaminants weaken the binding between the inorganic filler and the resin matrix. In addition, they inhibit the binding of a silane coupling agent onto the inorganic filler surface. Thus, a cleaning method for removing surely the contaminants from the inorganic filler is being investigated.
As a conventional cleaning method for inorganic fillers, a cleaning method in which water or a solvent has been generally applied, to remove contaminants by utilizing its dissolving power or diffusing power, has been generally employed. Water, low-boiling point paraffinic hydrocarbons, high-boiling point petroleum hydrocarbons, alcohols, or surfactants are mainly used in this method. However, water has a low dissolving power to oily organic substances, so that sufficient cleaning effects cannot be expected; and although the low-boiling point paraffinic hydrocarbons have a high dissolving power to oily organic substances, they involve problems against ignition or explosion during the use. Also, the high-boiling point petroleum hydrocarbons have such defects that a dissolving power to oily organic substances is low and that their removal and drying after the cleaning are difficult. Further, the alcohols are not effective against oily organic substances, have risks of ignition or explosion during the use, as well as the low-boiling point paraffinic hydrocarbons. Although the surfactants can remove oily organic substances or aqueous stains to some extent, it is difficult to remove the surfactants themselves after the cleaning.
As described above, a special attention is required to the handling for the conventional cleaning methods of inorganic filler. In addition, contaminants on the inorganic filler surface cannot be thoroughly removed, thus, it is pointed out that the binding between the inorganic filler and the resin matrix is insufficient, resulting in low durability of the dental resin restorative used in an oral cavity for a long period. In other words, the strength of the dental resin material is gradually lowered.
SUMMARY OF THE INVENTION
An object of the present invention is to develop a method of cleaning of an inorganic filler, upon which the inorganic filler used in resin materials for industrial or biological use, particularly dental resin restorative materials, can be more firmly bound to a resin matrix as well as a method of surface processing of the inorganic filler.
In order to solve the above-mentioned object, we, the present inventors made extensive and intensive investigations. As a result, it has been found that when, in cleaning of an inorganic filler, the removal of organic substances, such as carbon, on a surface of the organic filler is carried out with an aqueous solution of a peroxo acid and/or a peroxo acid salt, the danger as seen in the low-boiling point paraffinic hydrocarbons, the alcohols, and soon, is low, and the organic substances, such as carbon, on the inorganic filler surface can be surely removed, and further that when a surface processing with a silane coupling agent is carried out subsequently, the inorganic filler can be bound more firmly to the resin matrix, leading to accomplishment of the present invention.
More specifically, the method of cleaning of an inorganic filler according to the invention is a method of cleaning of an inorganic filler, which comprises cleaning of a surface of an inorganic filler with an aqueous solution of a peroxo acid and/or a peroxo acid salt, washing of the cleaned inorganic filler with water, and then cleaning of it with an organic solvent.
Further, the inventors have found that more preferred results are obtained when an aqueous solution of a peroxo acid and/or a peroxo acid salt having a concentration of 0.001% by weight to 10 by weight is used as the aqueous solution, and further, when sodium peroxodisulfate is used as the peroxo acid salt.
Moreover, the method of surface processing of an inorganic filler according to the invention is a method of surface processing of an inorganic filler, which comprises subjecting of the inorganic filler cleaned by the above-mentioned method to a silane coupling processing.
DETAILED DESCRIPTION OF THE INVENTION
In the method of cleaning of the inorganic filler and the method of surface processing of the cleaned inorganic filler according to the invention, the inorganic filler is, first of all, cleaned with a solution of a peroxo acid and/or a peroxo acid salt. Specific examples of the inorganic filler, which is applied to the method of cleaning of the inorganic filler and the method of surface processing of the cleaned inorganic filler according to the invention, include quartz, colloidal silica, feldspar, alumina, strontium glass, barium glass, borosilicate glass, titania, and fluoroaluminosilicate glass. Further, the methods of the invention can also be applied to organic-inorganic composite fillers prepared by mixing of the above-mentioned inorganic filler with a resin matrix, polymerizing and curing of the mixture, and then pulverizing of the cured product.
Examples of the peroxo acid and/or the peroxo acid salt, which can be used in the method of cleaning of the inorganic filler and the method of surface processing of the cleaned inorganic filler according to the invention include sodium peroxodicarbonate, potassium peroxodicarbonate, peroxodisulfuric acid, sodium peroxodisulfate, potassium peroxodisulfate, peroxophosphoric acid, sodium peroxophosphate, and potassium peroxophosphate. The aqueous solution of the peroxo acid and/or the peroxo acid salt has preferably a concentration of the peroxo acid and/or the peroxo acid salt of 0.001% by weight to 10% by weight, and more preferably 0.05% by weight to 10% by weight. In the case where the concentration is lower than 0.001% by weight, the cleaning effects are low, so that the characteristics of the invention tend to be hardly obtained. On the other hand, even when an aqueous solution having a concentrati
Okazaki Masayuki
Shintani Hideaki
Shirai Kenichi
Usuki Daisuke
Van Meerbeek Bart
GC Corporation
Kopec Mark
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Petruncio John M
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