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
1999-07-14
2001-01-16
Mullis, Jeffrey (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S242000, C525S267000, C526S075000, C526S213000, C526S218100, C526S303100, C526S306000, C526S307000, C526S307600, C526S317100, C526S911000, C526S932000
Reexamination Certificate
active
06174963
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an amphoteric resin (copolymer) having function as a dispersant which is used for dispersing a functional compound. More particularly, it relates to a method for producing an amphoteric resin having function as a dispersant or a binder for functional compounds which resin is excellent in dispersibility for functional compounds such as pigments and excellent in wettability with the functional compounds, and consequently provides satisfactory weather resistance for the resin after dispersion (dispersion system).
Familiar functional compounds are pigments used for paints and inks, and these are generally used in combination rather than being used each alone. As well known, when these functional compounds are used in combination, since they differ in surface chemical characteristics, resins are demanded which have excellent function as a dispersant such that dispersibility for the functional compounds is not different so much even in any combination of the compounds differing in surface characteristics. Especially, at present, paints and inks are required to have weather resistance and endurance, and hence it is strongly demanded that wettability of functional compounds concerning these properties with binders, namely, dispersibility of the compounds in binders is satisfactory.
Conventionally, for giving good dispersibility to various pigments, it is proposed to use as a resin for dispersion of pigment a graft copolymer which comprises an acrylic resin in which is incorporated a basic prepolymer comprising an amino group-containing polymerizable compound such as dimethylaminoethyl methacrylate. (See, for example, JP-B-Hei 5 (1993)-49715, JP-Appln. No. Sho 58 (1983)-91930, and JP-A-Sho 59 (1984)-217769).
However, although the conventionally proposed acrylic copolymers grafted with basic prepolymer are superior in dispersibility for acidic pigments, they are inferior in dispersibility for basic pigments to cause sometimes a phenomenon of pigment separation as floating or flooding or pigment agglomeration. Moreover, since the basic prepolymers comprise amines such as dimethylaminoethyl methacrylate, if they are used in a large amount, the coat is yellowed and damaged in weather resistance. Thus, it is difficult to obtain a resin system having desirable dispersing function.
On the other hand, it is proposed for obtaining resins superior in weather resistance to use cyclohexyl methacrylate as a monomer (See, for example, JP-A-Hei 6 (1994)-207142). However, though resins prepared using cyclohexyl methacrylate are superior in weather resistance, the phenomenon such as pigment separation as floating or flooding or pigment agglomeration caused by the inferior pigment dispersibility cannot be avoided. Thus, for satisfying both the dispersibility for the functional compounds and the weather resistance for the resin after dispersion, it can be considered to use the above-mentioned resins of both types. However, sufficient effect cannot still be obtained even with using the resins in combination.
SUMMARY OF THE INVENTION
The object of the present invention is to provide resins which are effective for improving simultaneously dispersibility for the functional compounds, endurance and weather resistance of the resulting resins and especially which can disperse indiscriminately any of acidic and basic functional compounds irrespective of using each alone or in combination.
As a result of intensive research conducted by the inventors in an attempt to develop resins having characteristics to improve both the dispersibility and the weather resistance, they have succeeded in obtaining a novel amphoteric resin by graft copolymerizing a basic prepolymer and an acidic prepolymer on the main chain of a polymer. Thus, the present invention has been accomplished.
The present invention is a method for producing an amphoteric resin having dispersing function which comprises polymerizing the following prepolymer A
2
, prepolymer B
2
and component C as essential components to graft copolymerize the prepolymer A
2
and the prepolymer B
2
on the main chain of the polymer of the component C so that amount of A
2
is in the range of 0.1-85% by weight, that of B
2
is in the range of 0.1-85% by weight, and that of C is in the range of 0.1-96% by weight with the total amount of A
2
, B
2
and C being 100% by weight:
prepolymer A
2
which is copolymerizable and has a copolymerizable double bond and an amino group and an acid group together and which is obtained by reacting a prepolymer A
1
having a weight-average molecular weight of 1000-30000 and being obtained by polymerization of a polymerization initiator having a carboxyl group at an end, an amino group-containing &agr;, &bgr;-ethylenically polymerizable compound and other &agr;, &bgr;-ethylenically polymerizable compound, with a compound having an epoxy group represented by the following formula (I):
(wherein R
1
represents H or a methyl group, and R represents a straight or branched chain alkyl group of 1-10 carbon atoms) in an amount of 0.1-1.0 equivalent for amino group equivalent of the prepolymer A
1
;
prepolymer B
2
which is copolymerizable and is obtained by reacting a prepolymer B
1
having a weight-average molecular weight of 1000-30000 and being obtained by polymerization of a polymerization initiator, a carboxyl group-containing &agr;, &bgr;-ethylenically polymerizable compound and other &agr;, &bgr;-ethylenically polymerizable compound, with a compound having an epoxy group represented by the above formula (I) in an amount of 0.1-1.0 equivalent for carboxyl group equivalent of the prepolymer B
1
; and
component C which is &agr;, &bgr;-ethylenically copolymerizable with A
2
and B
2
.
DETAILED DESCRIPTION OF THE INVENTION
The embodiments of the present invention will be explained in more detail.
In the present invention, the prepolymer A
1
is a prepolymer having a weight-average molecular weight of 1000-30000 which is obtained by the solution polymerization of an amino group-containing &agr;, &bgr;-ethylenically polymerizable compound and other polymerizable compound using a polymerization initiator containing a carboxyl group at an end by a conventional polymerization method at a temperature of 80-180° C. in a nitrogen stream.
The polymerization initiators having a carboxyl group at an end used in the present invention include, for example, 4,4′-azobis-4-cyanovaleric acid.
The amino group-containing &agr;, &bgr;-ethylenically polymerizable compounds used in the present invention include, for example, acrylates such as dimethylaminomethyl acrylate, diethylaminomethyl acrylate, dibutylaminomethyl acrylate, dihexylaminomethyl acrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, di(t-butyl)aminoethyl acrylate, diisohexylaminoethyl acrylate, dihexylaminopropyl acrylate, and di(t-butyl)aminohexyl acrylate, and methacrylates corresponding to these acrylates. These may be used each alone or in combination. It is necessary that amount of the amino group-containing polymerizable compound is at least 30% by weight of the components of the prepolymer A
1
. If it is less than 30% by weight, the resulting resin (copolymer) cannot completely or sufficiently disperse an acidic pigment.
The other &agr;, &bgr;-ethylenically polymerizable compounds used in the present invention include, for example, (1) monomers, e.g., alkyl or cycloalkyl esters of acrylic acid or methacrylic acid, such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, n-butyl methacrylate, i-butyl acrylate, i-butyl methacrylate, t-butyl acrylate, t-butyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate, and lauryl methacrylate, (2) vinyl monomers such as styrene, vinyltoluene, &agr;-methylstyrene, vinyl acetate, acrylonitrile, and methacrylonitrile, and (3) monomers, e.g., hydroxyalkyl esters of acrylic acid or methacrylic acid, such as 2-hydroxyethyl acrylate, 2-h
Kuroda Yasuo
Tamazawa Mitsuo
Mullis Jeffrey
Pillsbury Madison & Sutro LLP
Taisei Chemical Industries, Ltd.
LandOfFree
Method for producing amphoteric resin having dispersing... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for producing amphoteric resin having dispersing..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for producing amphoteric resin having dispersing... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2509568