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Rubber Toughened Powder Coatings

IP.com Disclosure Number: IPCOM000108138D
Original Publication Date: 1992-Apr-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 1 page(s) / 48K

Publishing Venue

IBM

Related People

Allen, RD: AUTHOR [+4]

Abstract

The majority of the powder coatings used today are based on acrylic polymers which have brittle mechanical properties. Toughening of such brittle films generally requires the incorporation of a dispersed rubbery phase. However, the rubber precursors are viscous liquids and not amenable towards conventional powder deposition processes. A strategy was developed to rubber toughen powder coatings while retaining standard deposition processes. This involves the use of a reactive, semicrystalline polymer which has a Tg below room temperature and a melting point of approximately 100~C. Furthermore, the polymer should have sufficient crystallinity to be a hard solid at room temperature, which allows the material to be processed (i.e., milled) into a fine powder.

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Rubber Toughened Powder Coatings

      The majority of the powder coatings used today are based on
acrylic polymers which have brittle mechanical properties. Toughening
of such brittle films generally requires the incorporation of a
dispersed rubbery phase.  However, the rubber precursors are viscous
liquids and not amenable towards conventional powder deposition
processes.  A strategy was developed to rubber toughen powder
coatings while retaining standard deposition processes.  This
involves the use of a reactive, semicrystalline polymer which has a
Tg below room temperature and a melting point of approximately 100~C.
Furthermore, the polymer should have sufficient crystallinity to be a
hard solid at room temperature, which allows the material to be
processed (i.e., milled) into a fine powder.  Once copolymerized into
a network, crystallination is prevented, leaving a low Tg-dispersed
rubber in the network.  One example involves the use of
methacrylate-terminated poly(ethylene oxide), PEO, a highly
crystalline material with a Tg approaching -60~C and a melting point
of 70~C.  Thus, PEO was readily milled and size classified as a
friable powder and was used to rubber toughen brittle networks.
Co-deposition with styrinic networks or vinyl ether-based urethanes
produced a homogenous mixture upon melting.  After polymerization,
the PEO forms a discrete rubber phase with no evidence of
crystallization.  The resulting modified networks showed substantial
improvement...