Plastic and nonmetallic article shaping or treating: processes – Recycling of reclaimed or purified process material
Reexamination Certificate
2002-01-25
2004-02-24
Lechert, Jr., Stephen J. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Recycling of reclaimed or purified process material
C264S109000, C264S118000, C264S122000, C264S128000, C264S140000, C241S003000
Reexamination Certificate
active
06695993
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a process for forming particulate materials, especially fiber materials, and binders into articles that are recyclable after comminution.
2. Background Art
Fiberboard is often manufactured using pulverulent binders based on crosslinkable and noncrosslinkable addition polymers. Noncrosslinkable binders used include for example polypropylene (PP) or polyethylene (PE). Since polyethylene and polypropylene are thermoplastic, fiberboard manufactured using polypropylene or polyethylene deforms at high temperatures because of its low heat resistance.
In contrast, fiberboard manufactured using crosslinkable binders such as phenolic resins or styrene-acrylate copolymers having crosslinkable groups possesses very good thermal deformation resistance (EP-A 894888, DE-A 10014399). Fiberboard of this type has the disadvantage, however, of being impossible to recycle owing to the irreversible, chemical crosslinking. Fiberboard of this type can at most be comminuted and ground and the material obtainable thereby reused as a filler.
EP-A 807704 discloses a process for recovering fibers from fiber materials wherein the fibers are ionically bonded by a carboxyl-functional polymer whose carboxyl groups are crosslinked by an alkaline earth metal ion. The process comprises treating the fiber material with an aqueous solution of a salt whose anion forms a sparingly soluble salt with the alkaline earth metal cations and then removing the debindered fibers.
DE-A 19535792 describes a process for preparing recyclable fiber composites by bonding the fibers together using an aqueous polymer dispersion whose film is converted into an aqueous addition polymer solution upon a change of pH. After the bonding agent, or binder, has been converted into an aqueous solution, the fiber material can be removed and fibers and binders reused.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a process for forming articles, especially from fiber materials, which possess a high thermal deformation resistance and are recyclable.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
These and other objects are achieved by a process for forming particulate materials and binders into articles that are recyclable after comminution, wherein the particulate materials are treated with a binder composition containing
A) one or more polymers consisting at least one comonomer unit selected from vinyl esters of branched or unbranched alkyl carboxylic acids of 1 to 18 carbon atoms, acrylic or methacrylic esters of branched or unbranched alcohols of 1 to 15 carbon atoms, dienes, olefins, vinyl aromatics and vinyl halides, and further containing 4 to 60% by weight, based on the total weight of the copolymer, of one or more units containing polar groups, and
B) 4 to 25% by weight, based on the total weight of polymer and filler, of one or more fillers having a polar surface capable of interaction with the polar groups of polymer(s) A). The binder-containing particulate materials are then formed into articles and consolidated.
Useful vinyl esters include vinyl esters of branched or unbranched carboxylic acids of 1 to 18 carbon atoms. Preferred vinyl esters are vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, vinyl laurate, 1-methylvinyl acetate, vinyl pivalate and vinyl esters of &agr;-branched monocarboxylic acids of 5 to 11 carbon atoms, for example VeoVa9
R
or VeoVa10
R
vinyl esters (trade names of Shell). Vinyl acetate is particularly preferred.
Useful monomers from the group of the esters of acrylic acid or methacrylic acid include esters of branched or unbranched alcohols of 1 to 15 carbon atoms. Preferred methacrylic esters or acrylic esters are methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, n-butyl acrylate, n-butyl methacrylate, t-butyl acrylate, t-butyl methacrylate, 2-ethylhexyl acrylate, norbornyl acrylate. Particular preference is given to methyl acrylate, methyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate and norbornyl acrylate.
Useful dienes include 1,3-butadiene and isoprene. Examples of copolymerizable olefins are ethene and propene. Useful vinyl aromatics for copolymerization include styrene and vinyltoluene. Vinyl chloride is the customary vinyl halide.
Useful polar groups are, for example, carboxyl, hydroxyl, phosphonate, sulfonate or NH groups.
Useful carboxyl-functional comonomers for copolymer A) include ethylenically unsaturated mono- and dicarboxylic acids, preferably acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid and maleic acid. The carboxyl function may also be introduced by copolymerizing maleic anhydride into the copolymer A). Useful hydroxyl-functional comonomers include hydroxyalkyl acrylates and hydroxyalkyl methacrylates having a C
1
- to C
8
-alkyl radical, preferably hydroxyethyl acrylate and methacrylate, hydroxypropyl acrylate and methacrylate, and hydroxybutyl acrylate and methacrylate. Useful NH-functional comonomers include (meth)acrylamide, diacetoneacrylamide, maleimide, alkyl maleamate, alkyl fumaramate, maleamide, fumaramide, vinyl glutaramate, vinyl succinamate, allyl glutaramate, allyl succinamate, dimethylaminoethyl methacrylate, dimethylaminopropylmethacrylamide, trimethylammonium methyl methacrylate chloride, and trimethylammonium propylmethacrylamide chloride. A useful phosphonate-functional comonomer is vinyl phosphonate. Useful sulfonate-functional comonomers include vinyl sulfonate, styrenesulfonic acid, and 2-acrylamido-2-methylpropanesulfonic acid.
Preference is given to carboxyl-functional comonomer units, preferably those derived from acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid and maleic anhydride. The fraction of functional units in copolymer A) is in the range from 4 to 60% by weight and preferably in the range from 5 to 25% by weight, each percentage being based on the total weight of the copolymer. Each polar comonomer may be used to the exclusion of one or more of other polar comonomers.
Preference is given to the polymer compositions specified below for copolymer A), which additionally includes, in the foregoing amounts, the functional group-containing monomer units previously described:
vinyl acetate polymers; vinyl ester-ethylene copolymers, such as vinyl acetate-ethylene copolymers; vinyl ester-ethylene-vinyl chloride copolymers where the vinyl ester component is preferably vinyl acetate and/or vinyl propionate and/or one or more copolymerizable vinyl esters such as vinyl laurate, vinyl pivalate, vinyl 2-ethylhexanoate, vinyl esters of an alpha-branched carboxylic acid of 5 to 11 carbon atoms, especially vinyl versatate (VeoVa9
R
, VeoVa10
R
); vinyl acetate copolymers with one or more copolymerizable vinyl esters such as vinyl laurate, vinyl pivalate, vinyl 2-ethylhexanoate, vinyl esters of an alpha-branched carboxylic acid of 5 to 11 carbon atoms, especially vinyl versatate (VeoVa9
R
, VeoVa10
R
), which optionally contain ethylene as well; vinyl ester-acrylic ester copolymers, especially with vinyl acetate, butyl acrylate and/or 2-ethylhexyl acrylate, which optionally contain ethylene as well; vinyl ester-acrylic ester copolymers with vinyl acetate and/or vinyl laurate and/or vinyl versatate and acrylic esters, especially butyl acrylate or 2-ethylhexyl acrylate, which also optionally contain ethylene as well.
Particular preference is given to (meth)acrylic ester and styrene polymers: copolymers with n-butyl acrylate and/or 2-ethylhexyl acrylate; copolymers of methyl methacrylate with butyl acrylate and/or 2-ethylhexyl acrylate and/or 1 ,3-butadiene; styrene-1,3-butadiene copolymers and styrene-(meth)acrylic ester copolymers such as styrene-butyl acrylate, styrene-methyl methacrylate-butyl acrylate or styrene-2-ethylhexyl acrylate, where the butyl acrylate used can be n-, iso- or tert-butyl acrylate.
Most preference is given to compositions having a carboxyl-functional styrene-n-butyl acrylate
Hashemzadeh Abdulmajid
Kohlhammer Klaus
Pröbstl Herbert
Wierer Konrad Alfons
Brooks & Kushman P.C.
Lechert Jr. Stephen J.
Wacker Polymer Systems GmbH & Co. KG
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