Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2002-07-03
2004-07-13
Sellers, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C428S418000, C523S414000, C523S415000
Reexamination Certificate
active
06762252
ABSTRACT:
The present invention relates to a resin composition for coating and more specifically relates to a resin composition for cationic electrodeposition paint capable of forming a coating film excellent in electrodeposition property, coating surface smoothness and anticorrosivity in spite of small content of organic solvent and without containing a lead compound.
Electrodeposition paint is being used as undercoat paint for motorcar and for other wide range of application and products with various features have been developed hitherto. Particularly cationic electrodeposition paints, containing as base resin an epoxy resin containing an amino group as solubilizing group and an epoxy resin solubilized by a quaternary ammonium salt group etc., have been being widely used due to its excellent anticorrosivity, throwing power etc., replacing conventional anionic electrodeposition paints.
These cationic electrodeposition paints are generally water-based paints, but usually an organic solvent is used together in order to secure the electrodeposition property and coating surface smoothness. Further, a lead compound is compounded in order to secure the anticorrosivity. Though an organic solvent plays an important role at the time of an electrodeposited film formation, it is desirable to reduce its amount to the utmost from the viewpoint of VOC (volatile organic compounds). Moreover, a lead compound is a very harmful substance and its usage is problematic in the counter-measures against public pollution.
The main purpose of the present invention is to provide a resin composition for cationic electrodeposition paint without deflects as mentioned above and excellent in coating film properties such as anticorrosivity, coating surface smoothness etc. with low content of organic solvent and without containing a lead compound.
Means of Solving the Problems
The present inventors have been conducting an intensive research in order to solve the problems a cationic electrodeposition paint has as mentioned above. As a result, this time, they have found out that the above-mentioned purpose could be achieved by using as base resin a resin obtained by reacting an epoxy resin, in which a prescribed amount of alkylene oxide has been introduced, with a cyclic ester and has completed the present invention.
Thus, according to the present invention, there is provided a resin composition for coating comprising a modified epoxy-poly-amine resin (f), obtained by first reacting a diepoxide compound (a) selected from the group consisting of the compounds represented by the following general formulae (I) and (II)
wherein
R
1
represents a hydrogen atom or an alkyl group of 1-6 carbon atoms,
m and n are respectively a number of 0 or more, and the sum of m and n is in the range of 1-20,
x is an integer of 1-9,
y is a number of 1-50,
and a bisphenol A type epoxy resin of an epoxy equivalent 170-500 with a bisphenol (b), reacting the epoxy resin (c) thus obtained with a cyclic ester (d) represented by the following general formula (III)
wherein
R
2
represents a hydrogen atom or a methyl group,
p is an integer of 3-6,
and further reacting an amine compound having an active hydrogen to the modified epoxy resin (e) thus obtained.
The resin composition for coating of the present invention will be described hereinafter in more detail.
The diepoxide compound of the aforementioned formula (I) used as the component (a) in the present invention can be prepared, for example, by adding an alkylene oxide represented by the following formula (IV)
wherein R
1
has the aforementioned meaning, to bisphenol A according to a per se known process, and diepoxidizing by reacting the obtained polyether compound of hydroxyl terminal further with epihalohydrin. As an alkylene oxide of the above-mentioned formula (IV) used here there are mentioned, for example, an alkylene oxide of 2-8 carbon atoms such as ethylene oxide, propylene oxide, butylene oxide etc. and, above all, propylene oxide (the compound of the formula (IV) wherein R
1
is methyl) is preferred.
The addition mole number of alkylene oxide in the formula (I), namely, the number of the repeating unit of the alkylene oxide structure part m and n are respectively numbers of 0 or more, preferably in the range of 1-10, and the sum of m and n (m+n) can be a number in the range of 1-20, preferably 2-10.
The diepoxide compound of the aforementioned formula (II) as the component (a) can be prepared, for example, according to per se known processes, (i) by diepoxidizing by reacting epihalohydrin to the polyalkylene oxide of hydroxyl terminal obtained by ring-opening polymerization of an alkylene oxide of the aforementioned formula (IV) by using an alkylene glycol as mentioned below as initiator; or (ii) by diepoxidizing by reacting epihalohydrin to an alkylene glycol represented by the following formula (V)
wherein R
1
and x have the aforementioned meaning, or a polyether diol obtained by dehydrating condensation of 2 or more molecules of said alkylene glycol. As an alkylene glycol of the above-mentioned formula (V) used here there are mentioned alkylene glycols of 2-10 carbon atoms such as ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol etc.
In the above-mentioned formula (V) x can be an integer in the range of 1-9, preferably 1-6, and the number of the repeating unit of the alkylene oxide or alkylene glycol structure part y in the aforementioned formula (II) ban be a number in the range of 1-50, preferably 5-20.
According to the present invention an epoxy resin (c) is prepared first by reacting a bisphenol (b) with the above-mentioned diepoxide compound (a) combined with a bisphenol A type epoxy resin of an epoxy equivalent 170-500.
Here “bisphenol A type epoxy resin of an epoxy equivalent 170-500” to be combined with the diepoxide compound (a) and reacted with a bisphenol (b) includes substances of relatively low molecular weight having 2 or more epoxy groups in the molecule, obtained by reaction of bisphenol A and epihalohydrin, representatively represented by the following formula (VI)
wherein q is a number in the range of 0-5, preferably 0-3.
Said bisphenol A type epoxy resin can have an epoxy equilavent in the range of 170-500, preferably 200-400 and a number-average molecular weight in the range of 340-1500, preferably 400-1000.
On the other hand, a bisphenol (b) to be reacted with the above-mentioned diepoxide compound (a) and a bisphenol A type epoxy resin includes compounds represented by the following general formula (VII)
wherein
R
3
and R
4
each represents a hydrogen atom, an alkyl group of 1-6 carbon atoms, or a trifluoromethyl group,
R
6
, R
7
, R
8
, R
9
, R
10
, R
11
, R
12
and R
13
each represents a hydrogen atom or an alkyl group of 1-6 carbon atoms,
and there are mentioned specifically, for example, bis (4-hydroxyphenyl)-2,2-propane (bisphenol A), bis(4-hydroxyphenyl)-1,1-ethane, bis(4-hydroxyphenyl)-methane (bisphenol F) etc. Among them, particularly bisphenol A is preferred.
The reaction of the diepoxide compound (a) and bisphenol A type epoxy resin with a bisphenol (b) can be conducted by heating to a temperature of about 100-about 200° C., preferably about 120-about 170° C., usually without using a solvent, in an atmosphere of an inert gas such as nitrogen gas etc., suitably in the presence of a catalyst such as a tertiary amine like dimethylbenzylamine, tributylamine etc.; a quaternary ammonium salt like tetraethylammonium bromide etc. Said reaction is conducted until the epoxy equivalent of the formed epoxy resin (c) reaches in the range of 400-5000, particularly 500-2000.
The application ratio of the diepoxide compound (a), bisphenol A type epoxy resin and a bisphenol (b) is not strictly limited but can be varied according to the kinds of these components to be used etc. The diepoxide compound (a) is preferably used in the range of generally 5-50% by weight, particularly 10-40% by weight based upon the total solid content of the above-mentioned three components
Kamikado Koji
Nishida Reiziro
Kansai Paint Co. Ltd.
Sellers Robert
Wenderoth , Lind & Ponack, L.L.P.
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