Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2001-05-12
2004-09-14
Cain, Edward J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C106S491000, C523S216000, C524S493000
Reexamination Certificate
active
06790900
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a treatment agent for hydrophilicity preferable for the treatment for hydrophilicity of aluminum materials used for the heat exchanger part of air conditioner, air filter parts of air cleaner, etc., and a method for preparing said agent.
2. Background Art
The heat exchanger part of air conditioner and air filter part of air cleaner are complicated in structure wherein aluminum fins for the heat exchange and removal of atmospheric dust and microbes are held in narrow spaces between aluminum pipes. Therefore, it has been devised so as to facilitate the discharge of condensed water during the cooling operation by making the surface of aluminum fins, etc. hydrophilic. However, since the surface of aluminum fins, etc, which has been made hydrophilic as described above, is exposed to severe conditions including the repeated cycle of “heating←→cooling”, and adhesion of condensed water, atmospheric dusts or microbes, it is difficult to maintain the hydrophilicity of the surface of aluminum fins, etc. for a long period of time.
A variety of inventions have been hitherto made to solve these problems, and, for example, in Japanese Patent Laid-open Publication No. Hei 5-202313, a treatment agent for hydrophilicity comprising a mixture of polyvinyl alcohol and water-dispersible silica or a complex thereof, and lithium metasilicate has been disclosed. Herein, lithium metasilicate has been said to be effective in maintaining the lasting hydrophilicity, lowering the freezing point and expressing antimicrobial activity.
In addition, in Japanese Patent Laid-open Publication No. Hei 5-214273, a paint composition consisting of a water-soluble or water-dispersible organic resin, nitrogen-containing anticorrosive and silica particulates, and coated aluminum materials with coating film obtained from this paint composition have been disclosed.
Furthermore, in Japanese Patent Publication No. 2649297, a paint composition for fin materials made of aluminum or aluminum alloy containing water-soluble or water-dispersible organic resin (excluding water-soluble amino resins), water-soluble amino resin, water-dispersed agglutinating colloidal silica containing silanol groups of 50 m&mgr;~2 &mgr;m in particle size, or water-dispersible humed silica powder, and a surfactant with HLB value of 8~18, fin materials and a method for manufacturing these fin materials have been disclosed. This invention aims at obtaining a pre-coated type fin material and a hydrophilic coating film resistant to drawless processing (ironing) during the manufacturing of heat exchanger.
In addition, in Japanese Patent Laid-open Publication No. Hei 10-30069, an aqueous agent to give hydrophilicity containing colloidal silica of 5~100 nm in dispersed particle size and carboxylic acid polymer at pH 1~5, and a method for manufacturing pre-coated fin materials for the heat exchanger using this agent have been disclosed.
All of these aforementioned prior arts have aimed to enhance the hydrophylicity of paint compositions utilizing irregularities of silica surface by using water-soluble or water-dispersible resin together with colloidal silica or particulate silica. However, hydrophilic coatings formed by the combined use of resin and particulate silica tend to deteriorate due to the long time use of heat exchanger. As a result, particulate silica is exposed, posing problems such as emission of silica specific dust smell or stink from materials adsorbed on silica.
SUMMARY OF THE INVENTION
Therefore, it is an object of this invention to provide a treatment agent for hydrophilicity which enables the maintenance of deodorizing capability and hydrophilicity even after the long time use and is preferable for the treatment of aluminum materials to be used in the heat exchanger parts of air conditioner or air filter parts of air cleaner, and a method for manufacturing said agent.
A treatment agent for hydrophilicity of this invention comprises silica particulate and polymer of vinyl alcohol series in an aqueous medium in the weight ratio ranging from 30:70 to 70:30, amounting to 1~25 weight percent relative to the entire treatment agent, wherein said silica particulates are coated with polymer of vinyl alcohol series, and dispersed as coated particles of 5~1000 nm in the average particle diameter in said aqueous medium.
A method for preparing a treatment agent for hydrophilicity of this invention comprises the following processes:
(1) a process for dissolving or dispersing a polymer of vinyl alcohol series to make a concentration ranging 0.3~17.5 weight percent relative to the entire treatment agent,
(2) a process for adding silica particulates of 5~100 nm in the average particle diameter to a dissolution or dispersion system of polymer of polyvinyl alcohol series formed in said process (1) to make a concentration in the range of 0.3~17.5 weight percent relative to the entire treatment agent, maintaining a weight ratio between said silica particulates and said polymer of vinyl alcohol series ranging 30:70~70:30, and furthermore,
(3) a process for forcibly dispersing “aggregates of polymer of vinyl alcohol series with silica particulates” generated by the addition of said silica particulates.
A treatment agent for hydrophilicity according to this invention is preferable for aluminum materials such as aluminum fins, etc. of evaporator which are exposed to severe conditions including the repeated cycle of “heating←→cooling”, and adhesion of condensed water, atmospheric dusts or contaminating microbes.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
This invention will be described below in more detail.
The treatment agent for hydrophiliciity of this invention comprising silica particulates coated with polymer of vinyl alcohol series dispersed in aqueous medium is morphologically different from the conventional mixture of silica particulates and resin particles, or silica particulates bound to resin with a silane compound in prior arts.
Silica particulates usable as the raw material of treatment agents for hydrophilicity can be exemplified by humed silica and colloidal silica. Among them, humed silica is prepared by hydrolyzing halosilane such as trichlorosilane and tetrachlorosilane at high temperature in the vapor phase, which is particulate having large surface area. Colloidal silica is a silica sol of the acid- or alkali-stable type dispersed in water. The particle diameter of silica particulates is 5~100 nm, preferably 7~60 nm on the average. When this average particle diameter is less than 5 nm, the irregularity of treated coating film surface is not sufficient, resulting in the decrease in hydrophilicity, and when it exceeds 100 nm, aggregates of large particle diameter are formed in the preparation of treatment agents, aggravating the painting processability.
A typical polymer of vinyl alcohol series usable in this invention is polyvinyl alcohol (PVA) obtained by saponifying a vinyl acetate polymer. PVA with a high saponification level is preferred, especially the one with a saponification level exceeding 98% is preferred. Denatured PVAs, for example, PVA a portion of hydroxyl groups of which are substituted with alkyl groups such as propyl or butyl group can be also used as polymer of vinyl alcohol according to this invention. Furthermore, as the occasion demands, other hydrophilic polymers such as hydroxyl group-containing acrylic resins, polyacrylic acid, polyvinyl sulfonic acid, polyvinylimidazole, polyethylene oxide, polyamide, water-soluble nylon, etc. can be used together with PVA in the amount of less than 50 weight percent relative to PVA.
To prepare a treatment agent for hydrophilicity used in this invention, first, a polymer of vinyl alcohol series (and other hydrophilic polymer, when the occasion demands. Hereafter simply referred to as polymer of vinyl alcohol series.) is dissolved or dispersed to make the concentration 0.3~17.5 weight percent, preferably 0.5~5 weight percent relative to the entire treatment agent. To this mi
Inbe Toshio
Matsukawa Masahiko
Yoshida Tatsuo
Cain Edward J.
Nippon Print Co., Ltd.
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