Stock material or miscellaneous articles – Composite – Of epoxy ether
Patent
1986-02-03
1987-07-07
Nielsen, Earl
Stock material or miscellaneous articles
Composite
Of epoxy ether
427 13, 427386, 525504, 528111, 528104, C08G 5964
Patent
active
046787127
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to an adduct having terminal aliphatic --OH groups, a curable coating composition containing this adduct, a method for coating a substrate using this composition and to coated articles prepared therefrom.
Due to their physical and chemical properties such as high resistance to chemical attack and good adhesion to various substrates, epoxy resins are useful in the preparation of coatings. The epoxy resins can be applied from organic or aqueous solutions onto a variety of different substrates or sprayed, in a powder form, onto a metal substrate using electrostatic techniques.
Conventionally, in preparing a powder coating using an epoxy resin, the epoxy resin is blended with a hardener such as a compound containing one or more reactive phenolic hydroxyl groups, which reacts with the epoxide groups to form a hard, infusible coating. For example, a high molecular weight epoxy resin coating has been prepared in situ on a suitable substrate by applying a mixture of a solid component having more than one 1,2-epoxy group, a solid component having more than one phenolic hydroxyl group and a suitable catalyst to a substrate and subsequently heating the coated substrate to effect the reaction between the epoxy containing component and the phenolic hydroxyl containing component. If desired, the mixture can also contain dyes, pigments and flow control agents. The phenolic --OH containing component is prepared by reacting an excess of a phenolic compound having more than one phenolic --OH group with an epoxy compound having more than one epoxide group.
Although the adhesion of the coating prepared from the described epoxy resin composition to the substrate is generally sufficient, the adhesion of the cured resin coating to various metal substrates such as untreated mild steel substrates, could be improved, particularly when the cured coating is subjected to humid conditions.
Accordingly, this invention provides a curable coating composition useful in preparing a coating having improved adhesion. The curable coating composition comprises (1) a component having more than one 1,2-epoxy group and (2) a component having more than one group reactive with the epoxy groups of component (1) wherein at least one of components (1) and (2) is an adduct formed by reacting a compound containing at least one primary or secondary amino group and at least one aliphatic hydroxyl group with an epoxy resin and optionally a component reactive with the epoxy resin, said reaction product having terminal aliphatic --OH groups, and having epoxy groups or groups reactive with an epoxy group. Preferably, component (2) is a compound having more than one phenolic --OH group. Optionally, the coating composition can contain a catalyst for promoting the reaction between the epoxy and phenolic --OH groups and other adjuncts such as pigments, dyes and flow control agents. The reaction product of the compound containing at least one primary or secondary amino group and at least one aliphatic hydroxyl group with an epoxy resin and optionally a component reactive with the epoxy resin comprises an adduct of the epoxy resin with the compound containing at least one primary or secondary amine group and at least one aliphatic hydroxyl group, and may also include other materials, specifically unreacted starting material.
In a preferred embodiment, the coating composition is a powder coating composition. The powder coating composition of the present invention comprises (1) a component containing more than one 1,2-epoxy group, (2) a component having more than one phenolic --OH group wherein component (1) and/or component (2) is the reaction product of an epoxy resin or an epoxy resin and polyhydric phenol with a compound containing at least one primary or secondary amino group and at least one aliphatic hydroxyl group; said reaction product having terminal aliphatic --OH groups and epoxy or phenolic --OH groups. Preferably, both components (1) and (2) are normally solid materials, i.e., materials solid at room te
REFERENCES:
patent: 3317471 (1967-05-01), Johnson et al.
patent: 4152285 (1979-05-01), Thomassen
patent: 4162244 (1979-07-01), Bertram
patent: 4246148 (1981-01-01), Shimp et al.
patent: 4330644 (1982-05-01), Allen
Nielsen Earl
The Dow Chemical Company
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