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Subject: Elvace


From: Walter Henry <whenry>
Date: Sunday, January 3, 1993
In a recent DistList I wrote:

  One assumes he means EVA, Ethylene Vinyl Acetate, which is what Elvace

Looks like I was wrong.  Elvace is indeed properly called VAE, not EVA.
The order of mention indicates which is the major component.  I should
have realized this (and was probably taught it at some time or other,
but...).  Here is something from Blades "Vinyl Acetate-Ethylene
Copolymer Emulsions in Adhesives" (in Skeist. 2nd ed, I think).

  The development of ethylene-vinyl acetate resins with ethylene as the
  major monomer component occurred during the 1950's.  Such products are
  more readily related propertywise, to the polyethylenes and their
  commercial availability was favored since manufacture was adaptable to
  existing continuous systems for radical polymerization of ethylene.

  Today the commercially available poly(vinyl acetate-ethylene) polymers
  can be divided into three groups.

  1.  Those with low vinyl acetate content (ca 10 - 40 wt %).  These are
  used for hot-melt and plastic (molding) applications.  They are
  manufactured by polyethylene producers in a continuous bulk
  polymerization process at high pressures and marketed under trade
  names such as:  Elvax (duPont), Ultrathene (USI), Bakelite (UCC),
  Lupolen V (BASF), Alathon (duPont), Alkathene (ICI), and Montothene

  2.  Those with nearly equal vinyl acetate and ethylene contents (45-
  55 wt %).  These are used for specialty rubber applications and as a
  graft base for PVC polymerization for impact modification.  They are
  made in a solution copolymerization at medium pressures.  There is one
  dominant commercial product -- Levapren made by Farbenfabriken Bayer.

  3.  Those with high vinyl acetate content (ca 60 - 90%).  These are
  made by an emulsion polymerization process at 300 - 1500 psi.  They
  are thermoplastic resins sold under such trade names as: Airflex (Air
  Products and Chemicals, Inc), Elvace (duPont), Vinnapas (Wacker),
  Mowilith (Hoechst), Sumikaflex (Sumitomo), AmscoRes (Union Oil
  Corporation), and Vinivil (Montecatini Edison).  These products with
  5- 40 wt % ethylene in the copolymer appear  on the market almost
  exclusively as emulsions or dispersions in water.  They may be viewed
  as modifications of polyvinyl acetate with ethylene.  Such
  copolymerization in essence reduces they incidence of acetate
  functionality with respect to polyvinyl acetate as it occurs on the
  polymer chain.


  In this chapter, we shall deal with the vinyl acetate-ethylene
  copolymers in which the ethylene content is less than 40 wt %.  The
  other group of copolymers is treated in Chapter 30.

I included that last paragraph, because Chapter 30 happens to be Domine
and Schaufelberger, "Ethylene Copolymer Based Hot Melt Adhesives", in
which it is writ

  Ethylene vinyl acetate (EVA) copolymers represent by a wide margin,
  the major class of ethylene copolymers use commercially in hot melt

                  Conservation DistList Instance 6:35
                 Distributed: Thursday, January 7, 1993
                        Message Id: cdl-6-35-005
Received on Sunday, 3 January, 1993

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