Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-06-02
2001-02-27
Buttner, David J. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S375000, C524S376000, C524S377000, C524S378000, C524S611000, C525S467000
Reexamination Certificate
active
06194500
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a modified emulsion of polycarbonate resin and a process for production of said emulsion. More particularly, the present invention relates to a polycarbonate emulsion improved in adhesivity, water resistance and chemical resistance, as well as to a process for producing such a polycarbonate resin emulsion.
2. Description of the Prior Art
Polycarbonate resins, which are a thermoplastic resin, are superior in heat resistance, impact resistance, transparency and dimensional stability. Therefore, they are in wide industrial use as molded products such as electric or electronic parts and the like. Moreover, they have come to be used recently also as surface coatings for various base materials, owing to their properties.
These coatings have heretofore been used mainly as a solvent-based coating obtained by dissolving a polycarbonate resin in an organic solvent such as toluene, xylene, acetone, ethyl acetate, butyl acetate, cyclohexanone, methylene chloride, chloroform, dimethyl formamide, tetrahydrofuran, dioxane, dioxolan or the like. In recent years, however, a demand for a water-based coating (using no solvent) has increased in consideration of air pollution, fire hazard and environmental sanitation during application, associated with the solvent-based coating.
With respect to the demand for such a water-based coating containing a polycarbonate resin, there was proposed a process for producing the coating by emulsifying a polycarbonate resin in water using a small amount of an emulsifier. The water-based coating produced by such a process is free from the above-mentioned problems of solvent-based coatings containing a polycarbonate resin.
Water-based coatings containing a polycarbonate resin, however, have the following problems. That is, a polycarbonate resin itself has low adhesivity to a base material; when the polycarbonate resin is made into an aqueous emulsion using an emulsifier, the emulsifier has an adverse effect and, as a result, the polycarbonate resin comes to have even lower adhesivity.
Further, when a water-based coating of polycarbonate resin is applied to form a coating film, an emulsifier remains in the dried coating film and, as a result, the film has reduced water resistance and reduced chemical resistance (these problems can not be ignored).
SUMMARY OF THE INVENTION
The present invention has been completed in view of the above situation. The present invention has an object of providing (1) a modified emulsion of polycarbonate resin, which is improved in adhesivity, water resistance and chemical resistance and (2) a process for producing such a modified emulsion of polycarbonate resin.
According to the present invention there is provided a modified emulsion of polycarbonate resin, comprising a polycarbonate resin emulsion and a monocarbodiimide compound and/or a polycarbodiimide compound.
According to the present invention, there is also provided a process for producing a modified emulsion of polycarbonate resin, which comprises adding a monocarbodiimide compound and/or a polycarbodiimide compound to a polycarbonate resin emulsion.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is hereinafter described in detail.
The polycarbonate resin emulsion used in the present invention can be exemplified by an emulsion containing a polycarbonate resin and an adduct of (a) a polyhydric alcohol or an aromatic alcohol and (b) an alkylene oxide.
The polycarbonate resin used in the present invention can be exemplified by an ordinary-grade product having a molecular weight of 10,000 to 100,000 produced by using bisphenol A as a main raw material. Since a high molecular weight may make emulsification difficult, a polycarbonate resin having a molecular weight of 10,000 to 50,000 is preferred.
The polyhydric alcohol used for obtaining an adduct of a polyhydric alcohol and an alkylene oxide, used in the present invention can be exemplified by dihydric alcohols such as 1,4-butanediol, 1,6-hexanediol, neopentyl glycol and the like; and trihydric or higher alcohols such as trimethylolpropane, glycerine, pentaerythritol, castor oil, sorbitan and the like. A trihydric or higher alcohol is preferred.
The reason why a trihydric or higher alcohol is preferred, is presumed to be as follows. Since the polycarbonate resin used in the present invention has a high molecular weight, an emulsifier having a certain high molecular weight is necessary in order to emulsify the polycarbonate in water. In an adduct of a polyhydric alcohol, particularly a trihydric or higher alcohol and an alkylene oxide, the hydrophobic group has a relatively large molecular weight and the hydrophilic group is branched; therefore, even when the moles of alkylene oxide added are relatively large and the resulting adduct has a high molecular weight, the adduct has a balance between the hydrophobic group and the hydrophilic group and can satisfactorily emulsify the polycarbonate.
In contrast, merely when the moles of alkylene oxide added are large and the resulting adduct has a straight chain of high molecular weight, the adduct has a large hydrophilic group, is not balanced between the hydrophobic group and the hydrophilic group, and has no sufficient emulsification power.
The aromatic alcohol used for producing an adduct of an aromatic alcohol and alkylene oxide used in the present invention can be exemplified by monocyclic phenols (having one aromatic ring) such as phenol, phenol having at least one alkyl group, and the like; polycyclic phenols (having at least two aromatic rings) such as phenylphenol, cumylphenol, benzylphenol, bisphenol, naphthol and the like; and reaction products between monocyclic or polycyclic phenol and styrene, i.e. stryrenated phenols.
The alkylene oxide added to the polyhydric alcohol or the aromatic alcohol can be exemplified by alkylene oxides having 2 to 4 carbon atoms, for example, ethylene oxide (EO), propylene oxide (PO) and butylene oxide (BO). These alkylene oxides can be used in combination of two or more kinds. The addition form may be random or block. Ethylene oxide (EO) is particularly preferred and the moles of EO added are generally 5 to 250, preferably 30 to 200.
There is no particular restriction as to the method for adding the alkylene oxide to the polyhydric alcohol or the aromatic alcohol, and an appropriate known method can be used. The obtained adduct between (a) the polyhydric alcohol and/or the aromatic alcohol and (b) the alkylene oxide can be used singly or in combination of two or more kinds.
The polycarbonate resin emulsion used in the present invention can further contain, as necessary, a polyalkylene ether glycol having oxyalkylene units.
The polyalkylene ether glycol having oxyalkylene units can be exemplified by polyethylene glycol, polypropylene glycol and polybutylene glycol. The oxyalkylene units may be a combination of two or more kinds and may be random or block. Preferred is an ethylene oxide (Eo)-propylene oxide (PO) block polyalkylene ether glycol having a molecular weight of 5,000 to 20,000.
The polycarbonate resin emulsion used in the present invention can be, for example, one obtained by dissolving, in an organic solvent, a mixture of a polycarbonate resin, an adduct of (a) a polyhydric alcohol and/or an aromatic alcohol and (b) an alkylene oxide and, as necessary, a polyalkylene ether glycol having oxyalkylene units, then mixing the resulting solution with water to give rise to emulsification, and subjecting the resulting emulsion to solvent removal.
Specifically, first there is dissolved, in at least one kind of organic solvent selected from dimethylformamide, dioxane, dioxolan, toluene, chloroform, methylene chloride, etc., a polycarbonate resin (of an amount of 10 to 40% by weight, preferably 20 to 30% by weight based on the amount of the organic solvent), an adduct of (a) a polyhydric alcohol and/or an aromatic alcohol and (b) an alkylene oxide and, as necessary, a polyalkylene ether glycol having oxyalkylene units (the adduct and the polyalkylen
Imashiro Yasuo
Iwao Akito
Masaki Takao
Takahashi Ikuo
Buttner David J.
Kubovcik & Kubovcik
Nisshinbo Industries Inc.
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