Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From reactant having at least one -n=c=x group as well as...
Reexamination Certificate
2002-02-20
2004-02-24
Gorr, Rachel (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From reactant having at least one -n=c=x group as well as...
C528S075000, C525S123000, C525S124000
Reexamination Certificate
active
06696539
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a blocked isocyanate group-containing resin composition, and more particularly, it relates to a blocked isocyanate group-containing resin composition excellent in curability at low temperature and compatibility with base resins for paint and useful as a curing agent component, and a thermosetting composition containing the same.
BACKGROUND OF THE INVENTION
Recently, in view of the environmental preservation, it has been required to reduce the energy consumption at a paint baking step. On the other hand, the application of a baking paint to materials having a low thermal resistance has been desired owing to diversified substrates to be applied. For these demands, a paint wherein a resin having isocyanate groups blocked with an active methylene compound such as an acetoacetate ester or a malonate diester is used as a curing agent is promising because it is cured at a relatively low temperature. Various resins having isocyanate groups blocked with an active methylene compound are disclosed in, for example, Japanese Laid-Open Patent Publication Nos. 60-149572/1985, 57-121065/1982, 8-319332/1996, 10-231347/1998, 10-231348/1998.
However, the above resins having isocyanate groups blocked with an active methylene compound have defects that they sometimes crystallize at a low temperature or they tend to become inhomogeneous or clouded through phase separation into an islands-sea structure depending on the base resin component used owing to their low compatibility with common resins for paint. Therefore, they involve a problem that the kind of resins usable is limited and thus freedom at paint design is restricted. As a measure against the problem, Japanese Laid-Open Patent Publication No. 6-16769/1994 discloses a method of reacting, with a monohydric alcohol, isocyanate groups other than the isocyanate groups blocked with an active methylene compound. The method described in the publication improves the above defects to some extent but the compatibility with resins for paint is still insufficient.
On the other hand, in view of advanced environmental preservation, the use of water-based paints has been required. However, when the resins having isocyanate groups blocked with an active methylene compound are used as curing agents for water-based paints, the resulting water-based paints have poor viscosity-stability at storage and thus are accompanied by a problem that the paint viscosity decreases largely with the passage of time and the workability at painting remarkably lowers.
SUMMARY OF THE INVENTION
As a result of an extensive studies for solving the above problem, the present inventors have found that a resin obtainable by modifying a resin having blocked isocyanate groups of a specific structure with a specific alcohol and having a solubility parameter value lower than that of the resin before the modification is excellent in compatibility with various base resin components for paint and is useful as a curing agent, and therefore, they have accomplished the present invention.
The present invention relates a blocked isocyanate group-containing resin composition, comprising a resin (C) obtainable by modifying a resin (A) having, in one molecule, two or more blocked isocyanate groups represented by the following formula (I) or (II):
wherein R
1
, R
2
, R
3
, and R
4
, which are the same or different, each represents a substituent having 1 to 10 carbon atoms, with a monohydric alcohol (B) represented by the following formula (III):
R
5
OH (III)
wherein R
5
represents a substituent having 3 to 8 carbon atoms, whereby at least one of R
1
, R
2
, and R
3
in the blocked isocyanate group in the resin (A) is replaced by R
5
. The resin (C) exhibits a lowered solubility parameter as compared with the resin (A).
The resin (A) may be obtained by reacting the isocyanate groups in a polyisocyanate compound (a) having at least two isocyanate groups in one molecule with an active methylene compound (b). Part of the isocyanate groups in the polyisocyanate compound (a) may be reacted with a monohydric alcohol. The resin (A) may be a resin obtainable by homopolymerizing a vinyl monomer containing a blocked isocyanate group represented by the formula (I) or (II), or copolymerizing the monomer with other vinyl monomer.
The R
5
in the monohydric alcohol (B) may be a substituent having 5 to 18 carbon atoms containing no hetero atom. The monohydric alcohol (B) may be one or more selected from mono(or oligo)propylene glycol monoalkyl ethers having 4 to 10 carbon atoms, mono(or oligo)ethylene glycol monoalkyl ethers having 4 to 10 carbon atoms, and aliphatic alcohols having 4 to 10 carbon atoms. The R
5
in the monohydric alcohol (B) may be a group having more number of carbon atoms than the number of carbon atoms of least one of R
1
, R
2
, and R
3
in the resin (A).
The resin (C) may be obtainable by removing part or all of the alcohol derived from at least one selected from R
1
, R
2
, and R
3
in the blocked isocyanate groups in the resin (A). In this case, part or all of the alcohol derived from at least one selected from R
1
, R
2
, and R
3
in the blocked isocyanate groups in the resin (A) may be removed by heating and vacuuming operation.
PREFERRED EMBODIMENTS OF THE INVENTION
In the present invention, the resin (A) has two or more blocked isocyanate groups represented by the above formula (I) or (II) in one molecule, and is usually obtained by reacting the isocyanate groups in a polyisocyanate compound (a) having at least two isocyanate groups in one molecule with an active methylene compound (b). In the above formula (I) or (II), R
1
, R
2
, R
3
, and R
4
, which are the same or different, each represents a substituent having 1 to 10 carbon atoms, and the substituent may contains a hetero atom and is preferably a substituent having 1 to 8 carbon atoms.
Examples of the above polyisocyanate compound (a) include diisocyanates having 4 to 25 carbon atoms such as diphenylmethane-4,4′-diisocyanate (MDI), 1,5-naphthalene diisocyanate, tolylene diisocyanate (TDI), xylylene diisocyanate, 1,4-tetramethylene diisocyanate, 2-methyl-1,5-diisocyanatopentane (MPDI), 1,6-diisocyanatohexane (HDI), 2,2,4-trimethyl-1,6-hexamethylene diisocyanate (TMDI), lysine diisocyanate, 1-isocyanato-3,5,5-trimethyl-3-(isocyanatomethyl)cyclohexane (IPDI), dicyclohexylmethane-4,4′-diisocyanate (HMDI), m-tetramethylxylylene diisocyanate (TMXDI), diisocyanatonorbornane, and di(isocyanatomethyl)norbornane, triisocyanates having 6 to 30 carbon atoms such as 2-(isosyanatoethyl)-2,6-diisocyanatocaproate (LTI), adducts of these di- or triisocyanates with a polyhydric hydroxyl group-containing compound, a monohydric alcohol, or water; polyisocyanates containing a urethane structure, a biuret structure, an isocyanurate structure, an allophanate structure, or a urethodione structure, and having a number-average molecular weight of 300 to 20000 and an average number of isocyanate groups in one molecule of 2 to 100; polyisocyanates obtainable by homopolymerizing isocyanate group-containing vinyl monomers such as (meth)acryloyl isocyanate, 2-isocyanatoethyl (meth)acrylate, m-isopropenyl-&agr;,&agr;′-dimethylbenzyl isocyanate, and 1:1 adducts of hydroxyl group-containing vinyl monomers with the above diisocyanates, or copolymerizing the isocyanate group-containing vinyl monomers with other vinyl monomers such as (meth)acrylate esters and vinyl aromatic compounds, and having a number-average molecular weight of 1000 to 20000, and an average number of isocyanate groups in one molecule of 2 to 100; and the like. These may be used singly or as a combination of two or more of them. Moreover, a polyisocyanate derived from one of these various polyisocyanates, and one or more selected from polyhydric hydroxyl group-containing compound, water and monohydric alcohols having a molecular weight of 32 to 400, and having a number-average molecular weight of 300 to 20000 and an average number of isocyanate groups in one molecule of 2 to 100 can be also used as
Harakawa Hiromi
Ishii Hidekazu
Kobata Masami
Gorr Rachel
Kansai Paint Co. Ltd
Rader & Fishman & Grauer, PLLC
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