Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Patent
1987-01-23
1988-10-25
Nielsen, Earl
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
523414, 525510, 525528, 528108, 528109, 528110, 528111, 528113, 528122, 528341, 528374, C08G 5950, C08L 6302, C09D 544
Patent
active
047805242
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to water-dilutable binders for cationic electrocoating finishes based on modified epoxy resins containing ammonium, sulfonium and/or phosphonium groups.
Cationic electrocoating is a coating process frequently used especially for priming, in which synthetic resins carrying water-dilutable cationic groups are deposited by direct current on electrically conducting objects.
The use of modified epoxy resins as binders for cationic electrocoating finishes is known (U.S. Pat. Nos. 4,104,147; 4,260,720).
The modified epoxy resins that have been hitherto available for use in cationic electrocoating finishes are only poorly compatible with aliphatic hydrocarbons, are in need of improvement in respect of their flexibility and give rise to coats that cannot be overcoated without problems and have to be further thickened.
An object of the present invention was to develop novel modified epoxy resins that would be free from the disadvantages outlined above.
The object according to the invention was achieved by the development of binders which are obtainable by reacting epoxide equivalent weight below 2,000, with conditions, reacts monofunctionally with epoxide groups, or a mixture of such compounds, and with tertiary amine, a sulfide/acid mixture or phosphine/acid mixture or a mixture of these compounds, as well as, if desired, with polysulfide, a polyphenol or a mixture of these compounds, preferably from 4:1 to 1.5:1, the reaction of component A with component B being carried out at 100.degree. to 190.degree. C., if desired in the presence of a catalyst, and, if further desired, the dilutability with water being obtained by protonization with a water-soluble acid.
The novel modified epoxy resins can be obtained from readily accessible starting materials, and they are distinguished by good compatibility with aliphatic hydrocarbons and by high flexibility.
Their use in cationic electrocoating finishes gives rise to deposition of thick coats which can be satisfactorily overcoated.
It was found that the modification with the component B results in both an increase in flexibility and an increase in the thickness of the deposited coats.
A further reaction with the component D can lead to a further increase in flexibility of the modified eposy resins as well as to a further increase in the thickness of the deposited coats.
All compounds which contain two reactive epoxide groups and have an epoxide equivalent weight below 2,000, preferably below 1,000 and particularly preferably below 500, can e used as component A.
Diglycidyl ethers of polyphenols, prepared from polyphenols and epihalohydrins, are particularly preferred epoxide compounds. Examples of polyphenols which can be used are:
Other suitable compounds are 4,4'-dihydroxybenzophenone, bis-(4-hydroxyphenyl)-1,1-ethane, bis-(4-hydroxyphenyl)-1,1-isobutane, bis-(4-hydroxy-tert.-butylphenyl)-2,2-propane, bis-(2-hydroxynaphthyl)methane, 1,5-dihydroxynaphthalene and phenolic novolak resins.
Preferred epoxide compounds are also diglycidyl ethers of polyvalent alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,4-propylene glycol, 1,5-pentanediol, 1,2,6-hexanetriol, glycerol and bis-(4-hydroxycyclohexyl)-2,2-propane.
Diglycidyl esters of polycarboxylic acids, for example oxalic acid, succinic acid, glutaric acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, dimerized linolenic acid, etc., can be also used. Typical examples are glycidyl adipate and glycidyl phthalate.
Other suitable compounds are hydantoin epoxides, epoxidized polybutadiene and di-epoxide compounds, obtainable by epoxidization of an olefinically unsaturated alicyclic compound.
All compounds which contain a phenol or thiol group and react monofunctionally with epoxide groups under the reaction conditions prevalent in the preparation of the modified epoxy resins according to the invention can be used as component B.
Compounds of the general formula R.sup.1 --OH, in which R.sup.1 can have the following meaning ##STR1## R.sup.2 =H, al
REFERENCES:
patent: 4246089 (1981-01-01), Hazan
patent: 4593078 (1986-06-01), Kooymans et al.
patent: 4609446 (1986-09-01), Geist et al.
patent: 4609691 (1986-09-01), Geist et al.
patent: 4624974 (1986-11-01), Geist et al.
patent: 4686248 (1987-08-01), Bekooij et al.
Dobbelstein Arnold
Geist Michael
Ott Gunther
Schon Georg
BASF Lacke & Farben AG
Nielsen Earl
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