Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-09-27
2002-04-16
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C523S411000, C523S412000, C525S107000, C525S114000, C525S117000, C525S119000, C525S121000, C428S418000
Reexamination Certificate
active
06372823
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cationically electrodepositable coating composition forming a coating film which does not cause cissing and is excellent in performances such as a flatness, an adhesion to an adjacent coating film and a chipping resistance.
2. Description of the Prior Art
A cationically electrodepositable coating material is excellent in a throwing property and-a corrosion resistance and therefore is used for an undercoating material for car bodies in many cases. For the sake of rust-prevention and cissing prevention on a coated surface, a scaly pigment such as talc and silica and a vinyl resin having a low solubility parameter value (SP value) are added, and a hydrophilic plasticizing component is added to a terminal of a base epoxy resin.
However, caused are the problems that addition of a scaly pigment and addition of a hydrophilic plasticizing component to an epoxy resin reduce a corrosion resistance, an impact resistance and a chipping resistance of a coating film and a flatness on a coated surface and that addition of a vinyl resin having a low SP value reduces an adhesive property with an adjacent intermediate coating film and top coating film.
A principal object of the present invention is to solve the problems described above and provide a novel cationically electrodepositable coating composition forming a coating film which prevents cissing from being caused on a coated surface without reducing throwing property and a corrosion resistance and is excellent in performances such as an impact resistance, a chipping resistance and an adhesive property with other coating films.
SUMMARY OF THE INVENTION
Thus, provided according to the present invention is a cationically electrodepositable coating composition comprising:
(A) a water-soluble or water-dispersible resin obtained by reacting a hydroxyl group of a bisphenol A type epoxy resin with a cyclic ester compound,
(B) a vinyl resin having a solubility parameter value of less than 9.6,
(C) polyalkylene glycol having a solubility parameter value of less than 9.6, and
(D) a pigment component having an average particle diameter of 0.5 &mgr;m or less.
The cationically electrodepositable coating composition of the present invention shall be explained below in detail.
DESCRIPTION OF SPECIFIC EMBODIMENTS
Component (A): water-soluble or water-dispersible resin obtained by reacting a hydroxyl group of a bisphenol A type epoxy resin with a cyclic ester compound
A bisphenol A type epoxy resin which constitutes the base of the resin component (A) is a resin having together a phenolic hydroxyl group and an epoxy group in a molecule, and to be specific, preferred is a resin having at least 0.5, particularly 0.8 to 2 phenolic hydroxyl groups on an average and at least 2, particularly 2 epoxy groups on an average in a molecule. Further, the above resin has preferably a number average molecular weight falling in a range of usually about 400 to about 1000, particularly about 450 to about 700.
Such bisphenol A type epoxy resin includes, for example, 2,2-bis(4-hydroxyphenyl)propane(bisphenol A); 1,1-bis(4-hydroxyphenyl)ethane; bis(4-hydroxyphenyl)methane(bisphenol F); 4,4′-dihydroxydiphenylsulfone (bisphenol S); and glycidyl ethers of polyphenols such as a phenol novolak and a cresol novolak, and polymers thereof. In particular, bisphenol A is suited.
The cyclic ester compound which is reacted with such bisphenol type epoxy resins as described above includes, for example, lactones having 3 to 10 carbon atoms, such as &dgr;-valerolactone, &egr;-caprolactone, &zgr;-enalactone, &eegr;-caprylolactone, &ggr;-valerolactone, &dgr;-caprolactone, &egr;-enalactone and &zgr;-caprylolactone. In particular, &egr;-caprolactone is suited.
The component (A) can be obtained by subjecting a hydroxyl group of the bisphenol A type epoxy resin to a ring-opening addition reaction with the cyclic ester compound. This resin component (A) has a number average molecular weight falling preferably in a range of usually about 1000 to about 7000, particularly about 2000 to about 5000.
This addition reaction can be carried out by known methods, for example, by heating at 100 to 250° C. for about one to about 15 hours in the presence of a catalyst for accelerating the reaction, for example, a titanium compound such as tetrabutoxytitanium and tetrapropoxytitanium, an organic tin oxide such as tin octylate, dibutyltin oxide and dibutyltin laurate, or stannous chloride.
A side chain which has a primary hydroxyl group excellent in a reactivity based on ring-opening of the cyclic ester compound and which has a large plasticizing capacity is introduced into the epoxy resin by this addition reaction, and therefore it is estimated that a coating film formed can be improved in a corrosion resistance, an adhesive property, an impact resistance, a chipping resistance and a finishing property by using a coating composition containing this epoxy resin.
A use amount of the cyclic ester compound is preferably controlled so that a content of a moiety contained in the resin component (A), which originates in the cyclic ester compound falls in a range of usually 5 to 40% by weight, particularly 10 to 35% by weight.
The resin component (A) thus obtained can be used as a cationically electrodepositable resin after an epoxy group contained in the above resin is reacted with an amino compound in order to make it water-soluble or water-dispersible and then neutralized with an acid.
The amino compound may be any one as long as it can be reacted with an epoxy group to introduce a secondary amino group or a tertiary amino group into the resin component (A) and includes aliphatic, alicyclic and aromatic-aliphatic primary or secondary amines. It includes, for example primary monoamines such as methylamine, ethylamine, n- or iso-propylamine, monoethanolamine and n- or iso-propanolamine; secondary monoamines such as diethylamine, diethanolamine, di-n- or iso-propanolamine, N-methylethanolamine and N-ethylethanolamine; and primary or secondary polyamines such as ethylenediamine, diethylenetriamine, hydroxyethylaminoethylamine, ethylaminoethylamine, methylaminopropylamine, dimethylaminoethylamine and dimethylaminopropylamine. Among these amino group-containing compounds, primary amines and N-hydroxyl secondary amines are preferably reacted in advance with ketone, aldehyde or carboxylic acid to be turned to aldimines, ketimines, oxazolines or imidazolines, and then they are preferably reacted with an epoxy group. A use amount of these amino group-containing compounds is preferably such an extent that the resulting resin has an amine value falling in a range of usually 15 to 100, particularly 30 to 80.
The acid used for neutralizing the resin component (A) reacted with the amino compound includes, for example, water-soluble organic acids such as formic acid, acetic acid, glycolic acid and lactic acid, and an extent of neutralization falls suitably in a range of 0.8 to 1.2 equivalent ratio.
Component (B): Vinyl Resin Having a Solubility Parameter Value of Less than 9.6
In the present specification, a solubility parameter value (hereinafter referred to as an SP value) of the vinyl resin can be determined by turbid point titration, and to be specific, it can be calculated according to the following equation of K. W. Suh and J. M. Corbett (Journal of Applied Polymer Science, 12, 2359, 1968):
SP
=
V
H
·
δ
H
+
V
D
·
δ
D
V
H
+
V
D
wherein V
H
is a volume proportion of n-hexane; V
D
is a volume proportion of deionized water; &dgr;
H
is an SP value of n-hexane and &dgr;
D
is an SP value of deionized water.
In the turbid point titration, n-hexane is slowly added to a solution prepared by dissolving 0.5 g (solid matter) of the dried vinyl resin in 10 ml of acetone, and a titrating amount H (ml) in the turbid point is read. Deionized water is added to the acetone solution in the same manner, and a titrating amount D (ml) in the turbid point is read. Then, these values are applied to the following equation
Furukawa Hidenori
Kasukawa Takahisa
Aylward D.
Dawson Robert
Kansai Paint Co. Ltd.
LandOfFree
Cationically electrodepositable coating 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 Cationically electrodepositable coating composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Cationically electrodepositable coating composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2876066