Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acid esters
Reexamination Certificate
2000-12-01
2002-03-26
Sergent, Rabon (Department: 1711)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acid esters
C428S413000, C428S423100, C428S447000, C428S473500, C428S474400, C428S500000, C428S524000, C523S400000, C523S402000, C523S414000, C523S415000, C524S507000, C524S555000, C524S502000, C524S588000, C524S589000, C524S590000, C524S591000, C524S600000, C524S606000, C524S608000, C524S612000, C524S831000, C524S838000, C524S843000, C524S845000, C524S869000, C540S202000, C525S123000, C525S124000, C525S329400, C525S418000, C525S454000, C525S456000, C525S474000, C525S504000, C525S509000, C525S523000, C525S528000, C528S
Reexamination Certificate
active
06362359
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to polyisocyanate-based resins containing modified hydrazide groups, to one-component, thermoset compositions containing these resins and a cross-linking component and to their use for the production of coatings, sealants and adhesives.
2. Description of the Prior Art
One-component polyurethane coating compositions derived from polyisocyanates blocked with reversible, monofunctional blocking agents for isocyanate groups and polyols are an important class of material for applications such as automotive OEM coatings. While these one-component compositions overcome the difficulties of two-component coating compositions with regard to accurate metering of the components, the one-component coating compositions also have disadvantages, which are primarily caused by the volatilization of the blocking agent.
The release of the blocking agent can cause blistering and yellowing in thick films and oven fouling. In addition, the blocking agents are considered to be volatile organic compounds (VOC's) in the same manner as organic solvents. Therefore, certain coating compositions may not satisfy environmental regulations solely due to the presence of blocking agents.
These disadvantages of one-component coating compositions can be overcome in accordance with the invention described in U.S. Pat. No. 6,127,514 and in copending application, U.S. Ser. No. 09/197,912 now U.S. Pat. No. 6,150,457. Instead of using mixtures of polyols and polyisocyanates blocked with reversible, monofunctional blocking agents, the patent and application describe one-component compositions containing compounds containing modified hydrazide groups and cross-linking agents such as melamine resins. These compositions do not require blocking agents and, thus, do not release blocking agents during cure. When these coating compositions are cured, the only compounds-released are water or monoalcohols, which are much less toxic than conventional blocking agents.
In accordance with the preceding patent and application, the compounds containing modified hydrazide groups are prepared, e.g., by the reaction of polyisocyanates with alkyl carbazates such as ethyl carbazate. Examples of suitable polyisocyanates include NCO prepolymers, polyisocyanate adducts and monomeric polyisocyanates. One disadvantage is that the reaction products of polyisocyanate adducts or monomeric polyisocyanates with alkyl carbazates are gels or extremely viscous materials that have poor solubility in most common solvents.
It is an object of the present invention to prepare compounds containing modified hydrazide groups from polyisocyanates, especially monomeric polyisocyanates or polyisocyanate adducts, which are readily soluble in known organic solvents and which can be cured without the release of blocking agents. It is an additional object of the present invention to be able to obtain coatings that possess chemical stability, including acid etch resistance, which is comparable to that obtained from coatings prepared using blocked polyisocyanates as the crosslinking agent.
These objects can be achieved with the one-component compositions according to the present invention. In these compositions the compounds containing modified hydrazide groups are also modified with ester residues. When these compositions are cured, the only compounds released are water or monoalcohols.
SUMMARY OF THE INVENTION
The present invention relates to compounds containing modified hydrazide groups and corresponding to formula I
wherein
R represents the residue obtained by removing the isocyanate groups from a monomeric polyisocyanate, a polyisocyanate adduct or an NCO prepolymer,
X represents OR′ or NHR′ and
R′ represents a group which is inert to isocyanate groups under the conditions used to form the polyurethane of formula I,
R″ represents a divalent, linear or branched aliphatic group containing 2 to 10 carbon atoms, provided that there are at least two carbons between the oxygen atoms, wherein the aliphatic group may optionally be substituted by heteroatoms to form ether or ester groups, and
n is 2to 6.
The present invention also relates to one-component, thermoset compositions containing the compounds of formula I and a cross-linking component that is reactive with these compounds. Finally, the present invention relates coatings, sealants and adhesives prepared from these thermoset compositions.
DETAILED DESCRIPTION OF THE INVENTION
The compounds of formula I are preferably prepared by reacting a polyisocyanate, R—(NCO)
n
, with a compound corresponding to formula II
wherein X, R′ and R″ are as previously defined.
The compounds corresponding to formula II may be prepared by reacting a compound corresponding to formula III
with a cyclic carbonate as described in U.S. Pat. No. 4,369,301. Suitable cyclic carbonates include ethylene carbonate, 1,2-propylene carbonate, 1,3-propylene carbonate and neopentyl carbonate. Ethylene carbonate and 1,2-propylene carbonate are preferred, and 1,2-propylene carbonate is especially preferred.
It is also possible to prepare the compounds of formula II by reacting the compounds of formula III with chloroformate hydroxyesters corresponding to formula (IV)
This method is suitable for preparing the compounds of formula II from compounds which cannot be converted into cyclic carbonates.
In formulas I, II, III and IV
X represents OR′ or NHR′, preferably OR′, and
R′ represents a group which is inert to isocyanate groups under the conditions used to form the compound of formula I, preferably an alkyl, cycloalkyl, araliphatic or aromatic group containing 1 to 20, preferably 1 to 10 carbon atoms, which may optionally be substituted by heteroatoms to form ether or ester groups,
R″ represents a divalent, linear or branched aliphatic group containing 2 to 10 carbon atoms, provided that there are at least two carbons between the oxygen atoms, wherein the aliphatic group may optionally be substituted by heteroatoms to form ether or ester groups, preferably a linear or branched alkylene group having 2 to 5 carbon atoms,
n is 2 to 6, preferably 2 to 4.
When X represents OR′, examples of R′ include methyl, ethyl, propyl, butyl, hexyl, octyl, phenyl, cyclohexyl and benzyl. Most preferably, R′ is an alkyl group having 1 to 4 carbon atoms. When X represents NHR, R′ is most preferably an alkyl group containing at least 4 carbon atoms.
Compounds corresponding to formula III wherein X represents NHR′ can be prepared by reacting hydrazine with an organic monoisocyanate in a molar ratio of 1:1.In order to increase the amount of product corresponding to formula III, it is also possible to use an excess amount of hydrazine and to remove the excess, e.g., by precipitation, distillation or extraction. However, this is generally not necessary since the selectivity to form the monoadduct is very high.
Examples of suitable polyisocyanates which may be used as the polyisocyanate component to prepare the compounds of formula I include monomeric polyisocyanates, polyisocyanate adducts and NCO prepolymers having an average functionality of 1.5 to 6, preferably 1.8 to 6, more preferably 2 to 6 and most preferably 2 to 4. Monomeric polyisocyanates and polyisocyanate adducts are preferred.
Suitable monomeric diisocyanates may be represented by the formula
R(NCO)
2
in which R represents an organic group obtained by removing the isocyanate groups from an organic diisocyanate having a molecular weight of about 112 to 1,000, preferably about 140 to 400. Preferred diisocyanates for the process according to the invention are those represented by the above formula in which R represents a divalent aliphatic hydrocarbon group having 4 to 40, preferably 4 to 18 carbon atoms, a divalent cycloaliphatic hydrocarbon group having 5 to 15 carbon atoms, a divalent araliphatic hydrocarbon group having 7 to 15 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms.
Examples of suita
Henderson Karen M.
Jacobs Patricia B.
Lee Sze-Ming
Sylvester Robert A.
Wicks Douglas A.
Bayer Corporation
Gil Joseph C.
Roy Thomas W.
Sergent Rabon
LandOfFree
One-component thermoset coating compositions does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with One-component thermoset coating compositions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and One-component thermoset coating compositions will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2847924