Aqueous binders

Details Aqueous binders Aqueous binders

2001-08-14

2003-06-03

Dawson, Robert (Department: 1712)

Stock material or miscellaneous articles

Composite

Of epoxy ether

C523S412000, C523S409000

Reexamination Certificate

active

06572972

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to aqueous binders.
BACKGROUND OF THE INVENTION
Air-drying resins or binders are known in particular in the field of alkyd resins; water-dilutable alkyd resins are obtained by mixing (unmodified) alkyd resins with emulsifiers or by incorporating a sufficient number of acid groups which remain following the condensation reaction and neutralizing at least some of them, or by cocondensation with hydrophilic polyoxyalkylene polyols such as polyethylene glycol.
For example, hydroxy-functional emulsifiers for alkyd resins based on polyurethane polyureas are known from EP-A 0 741 156. Other externally emulsified aqueous alkyd resin compositions are described in EP-A 0 593 487. Alkyd resins with a chemically incorporated emulsifier (self-emulsifying) are known from EP-A 0 312 733.
In all cases, compatibility with water is achieved by using nonionic or anionic emulsifiers, in chemically incorporated or added form.
It is also known to modify polyurethane resins, by incorporating unsaturated fatty acids (EP-A 0 444 454), in such a way that coating materials prepared using them are air-drying.
Resins containing epoxide groups, which by modification with fatty acids lead to air-drying binders, are described in EP-A 0 355 761 (esters of fatty acids with epoxy resins), 0 316 732, 0 370 299 (acrylic resins containing epoxide groups) and 0 267 562 (epoxide-ester resins, urethane-alkyd resins or alkyd resins grafted with olefinically unsaturated monomers in an aqueous medium).
Aqueous formulations of neutralized reaction products comprising epoxy resin-amine adducts and fatty acids are known from EP-A 0 070 704. Here, starting from amines and epoxy resins based on polyhydric phenols, adducts with a molar mass of from 1000 to 3000 g/mol are prepared and are subsequently reacted with unsaturated fatty acids to give a product in which the mass fraction of these fatty acids is from 25 to 50%. The amount of the fatty acids in this case is to be chosen such that all of the active amine hydrogen atoms are consumed.
AT-B 390 261 discloses epoxy resin ester emulsions which can be used as binders for air-drying coating materials. The resins are prepared by reacting epoxy resins, partially esterified with fatty acids, and copolymers of unsaturated fatty acids and (meth)acrylic acid, and also further copolymerizable monomers, and to achieve dilutability in water are at least partly neutralized with alkalis. These resins may also be admixed with amino-functional epoxy resin esters.
SUMMARY OF THE INVENTION
It has now been found that reaction products of epoxy resins and (optionally fatty-acid-modified) epoxide-amine adducts with an addition of bismuth compounds may be used as binders for air-drying and physically drying coating materials which bring about excellent corrosion protection on metallic substrates.
The invention accordingly provides aqueous binders comprising bismuth compounds D and reaction products A′ABC of epoxy resins A′ containing at least two epoxide groups per molecule and reaction products ABC of epoxy resins A, optionally fatty acids B and amines C, the number-average molar mass M
n
of the reaction products A′ABC being at least 5000 g/mol.
“Aqueous” binders are water-soluble binders and binders which form stable dispersions in water.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In particular, the molar mass calculated from the stoichiometry (number-average), M
n
, of these reaction products A′ABC is preferably at least 10,000 g/mol, more preferably at least 15,000 g/mol, and with particular preference at least 20,000 g/mol, and their (measured) acid number is not more than 5 mg/g. Following at least partial neutralization of the amino groups, the reaction products A′ABC can be dispersed in water to give stable dispersions which form no sediment even after the storage at room temperature (20° C.) for 4 weeks.
The epoxy resins A and A′ are selected independently of one another from diepoxide or polyepoxide compounds which are obtainable in a known manner by reacting epichlorohydrin with aromatic or (cyclo)aliphatic compounds containing two or more hydroxyl groups per molecule (Taffy process), or may be obtained by reacting diepoxides or polyepoxides with the aforementioned aromatic and (cyclo)aliphatic compounds containing two or more hydroxyl groups per molecule (advancement reaction). Preference is given to epoxy resins based on aromatic dihydroxy compounds, such as bisphenol A, bisphenol F, dihydroxydiphenyl sulfone, hydroquinone, resorcinol, 1,4-bis[2-(4-hydroxyphenyl)-2-propyl]benzene, or aliphatic dihydroxy compounds such as 1,6-hexanediol, 1,4-butanediol, cyclohexanedimethanol, or oligo- and poly-propylene glycol having average degrees of polymerization of between 3 and 40. The specific epoxide group content of the epoxy resins is, independently of one another for the epoxy resins A and A′, in each case preferably from 0.4 to 7 mol/kg, in particular from 0.6 to 6 mol/kg, the epoxide group content of A′ preferably being greater than that of A. In one preferred embodiment, diepoxide compounds are used in each case for A and A′, the specific epoxide group contents being from 0.5 to 4 mol/kg in the case of A and from 2 to 5.9 mol/kg in the case of A′.
Particular preference is given to epoxy resins based on bisphenol A and bisphenol F and mixtures thereof.
The optionally used fatty acids B contain at least one olefinic double bond and have from 6 to 30, preferably from 8 to 26, and in particular from 16 to 22 carbon atoms. Preference is given to palmoleic acid, oleic acid and erucic acid; linoleic acid, linolenic acid and eleostearic acid, arachidonic acid and clupanodonic acid, and also the fatty acids obtainable as mixtures from the naturally occurring oils, such as linseed oil fatty acid, soybean oil fatty acid, conjuvandol fatty acid, tall oil fatty acid, cottonseed oil fatty acid, rapeseed oil fatty acid, and the fatty acid mixtures obtained from dehydrated castor oil.
The amines C are preferably aliphatic, linear, cyclic or branched amines which contain at least one primary or secondary amino group. They have preferably from 2 to 12 carbon atoms and may also contain tertiary amino groups and/or hydroxyl groups as functional groups. Particularly suitable are primary monoamines having from 6 to 12 carbon atoms such as hexylamine, cyclohexylamine, 2-ethylhexylamine and stearylamine, primary diamines such as ethylenediamine, 1,4-diaminobutane and 1,6-diaminohexane, primary-tertiary diamines such as dimethylaminopropylamine, diethylaminopropylamine, diprimary-secondary amines such as diethylenetriamine, 1,9-diamino-5-azanonane, 1,13-diamino-7-azatridecane, triethylenetetramine and tetraethylenepentamine, and the mixtures of oligomeric diaminopolyethyleneimines available commercially as ®Polymin, and also secondary amines and diamines such as piperidine, piperazine, di-n-butylamine, morpholine, and hydroxy-functional amines such as ethanolamine, diethanolamine and diisopropanolamine. It is also possible to use mixtures of said amines.
The intermediates ABC may be prepared by sequential reaction (variant I), in which case the epoxide compounds A are first reacted with the amines C to give a product AC and in a second step these adducts are reacted with the fatty acids B to give the intermediate ABC. A further possibility, however (variant II), is first to react the epoxide compounds A with the fatty acids B to give a product AB and then to react the remaining epoxide groups in AB with the amines C. A further possibility (variant III) is to perform the reaction simultaneously and so in one step to arrive at the intermediates ABC. The amounts of the reactants A, B and C are chosen such that substantially all of the epoxide groups, i.e., at least 90%, preferably at least 95%, and in particular at least 98% of the epoxide groups originally present in A, are reacted. Preferably, the reaction is also to be conducted such that the intermediate ABC no longer contains any reactive amine

Affiliated with

Also associated with

Rating

Aqueous binders does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Aqueous binders, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Aqueous binders will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3147331