Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2001-06-05
2003-06-03
Niland, Patrick D. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S507000, C524S590000, C524S591000, C524S839000, C524S840000, C525S124000, C525S455000
Reexamination Certificate
active
06573329
ABSTRACT:
The invention relates to a process for preparing microsuspension polymers which are suitable for preparing coating materials. The invention also relates to the microsuspension polymers and to their use to produce fibers, moldings, films or coating materials, and also to the fibers, moldings, films or coating materials produced from them.
In the preparation of particulate addition polymers, microsuspension polymerization techniques are increasingly finding application alongside emulsion polymerization. In microsuspension polymerization, monomers or monomer mixtures are dispersed in water using protective colloids to form a dispersion and are subsequently polymerized using a hydrophobic free-radical polymerization initiator. DE-A-198 02 094 describes such a process with which elastomeric microsuspension (graft) polymers are obtained. By this means it is possible to obtain relatively large polymer particles. U.S. Pat. No. 5,889,111 describes the preparation of graft copolymers in which the graft core has an average particle diameter of from 1 to 150 &mgr;m. The preparation takes place by the microsuspension polymerization technique.
The elastomeric polymer particles obtained are used for impact modification of thermoplastic molding compounds.
It is an object of the present invention to provide microsuspension polymers crosslinkable by heating to a temperature of above 80° C. Dispersions of the microsuspension polymers are to be suitable for coating applications and for molding compounds which may be processed by injection molding, extrusion, thermoforming or compression molding and which crosslink to moldings during or after processing.
We have found that this object is achieved in accordance with the invention by a process for preparing microsuspension polymers by
(1) dispersing a mixture of components A1 to A4,
a1: from 0.1 to 60% by weight of at least one free-radically polymerizable monomer A1 containing at least one functional group which is reactive with isocyanate groups (isocyanate-reactive functional group),
a2: from 40 to 99.9% by weight of at least one further free-radically polymerizable monomer A2 containing no isocyanate-reactive functional group,
a3: from 0 to 20% by weight of 1,1-diphenylethene or 1,1-diphenylethane A3,
a4: from 0.1 to 100% by weight of at least one blocked polyisocyanate A4,
in water using a protective colloid to form a dispersion having an average particle diameter of from 0.08 to 100 &mgr;m, and
(2) polymerizing the droplets using from 0.1 to 20% by weight of at least one free-radical polymerization initiator, up to a conversion of at least 50% by weight,
the amounts being based on the total weight of components A1 and A2, which gives 100% by weight.
We have also found that the object is achieved by microsuspension polymers or dispersions thereof which may be prepared by this process.
By way of the microsuspension polymerization technique it is possible to carry out the polymerization with high monomer concentrations and high conversions without the dissipation of the developing heat of reaction becoming critical. Unlike polymerization in bulk or in solution, therefore, the polymerization system is easy to manage.
It is therefore also possible to operate with high initiator concentrations, thereby achieving rapid polymerization.
First of all, the individual components of the reaction system will be described in more detail.
All amounts by weight (% by weight) relate below to the total weight of components A1 and A2, which gives 100% by weight.
The free-radically polymerizable monomer A1 is used preferably in an amount of from 5 to 50% by weight, with particular preference from 10 to 40% by weight. The monomer A1 preferably contains at least one hydroxyl, primary or secondary amino, epoxy or carboxyl group. A secondary amino group preferably has a C
1-20
alkyl radical, preferably C
1-6
alkyl radical. In the epoxy group, the carbon atoms forming the epoxide ring may be substituted independently of one another by C
1-20
alkyl radicals, preferably C
1-6
alkyl radicals. The carboxyl group is preferably in the form of the carboxylic acid group —COOH. Preferably, the monomer has precisely one of said functional groups.
Examples of suitable monomers are hydroxyalkyl acrylates and hydroxyalkyl methacrylates of 1 to 20 carbon atoms, preferably 1 to 8 carbon atoms, in the alkyl group. Said alkyl group may be linear or branched. Examples are hydroxymethyl (meth)acrylate and hydroxybutyl (meth)acrylate. Further suitable monomers are propylene glycol (meth)acrylate and butanediol monoacrylate, glycidyl (meth)acrylate, (meth)acrylic acid, tert-butylaminoethyl (meth)acrylate, dimethyl-aminoethyl acrylate, dimethylaminoethyl methacrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, N-hydroxymethacrylamide, N-hydroxymethylmethacrylamide and 2-acrylamido-2-methylpropanesulfonic acid. Preference is given to hydroxy(methyl) methacrylates, especially hydroxypropyl methacrylate.
The monomer A2 is present preferably in an amount of from 50 to 95% by weight, with particular preference from 60 to 90% by weight. Preferred monomers A2 are selected from C
1-16
alkyl (meth)acrylates, unsubstituted or substituted styrene, acrylonitrile and mixtures thereof. In preferred alkyl (meth)acrylates, the alkyl radical has 1 to 8 carbon atoms. Examples are methyl methacrylate, butyl acrylate and ethylhexyl acrylate. Substituted styrenes may be substituted either in the ring or at the double bond; examples are p-methylstyrene and &agr;-methylstyrene. Preferred monomers A2 are methyl methacrylate, butyl acrylate, ethylhexyl acrylate and styrene.
As monomers A2 it is also possible, moreover, to use monomers having two or more polymerizable double bonds, such as butadiene, isoprene, divinyl esters of dicarboxylic acids, divinylbenzene and triallyl cyanurate or, with particular preference, dihydrodicyclopentadienyl acrylate. The fraction of these crosslinkers as a proportion of the total amount of the monomers A2 is preferably from 0 to 3% by weight, where they are present.
The monomer mixture may contain up to 20% by weight, preferably up to 4% by weight, with particular preference up to 3% by weight, of 1,1-diphenylethene (DPE) or diphenylethane (DPA). This compound results in a slower and smoother course of the polymerization and may be used with advantage especially in the case of a batch reaction. Furthermore, the use of DPE or DPA leads to a reduction in the molecular weight of the polymer, which is particularly advantageous in the context of the preparation of thin films and coating materials which are to be crosslinked subsequently. The same applies to low molecular mass polymers which are to be crosslinked after processing (for example, following injection molding).
Used as component A4 are from 0.1 to 100% by weight, preferably from 2 to 80% by weight, in particular from 20 to 70% by weight, of blocked polyisocyanates. The polyisocyanates have 2 or more isocyanate groups, preferably from 2 to 10 isocyanate groups.
Suitable blocking agents for preparing component A4 are described, for example, in U.S. Pat. No. 4,444,954:
i) phenols such as phenol, cresol, xylenol, nitrophenol, chlorophenol, ethylphenol, t-butylphenol, hydroxybenzoic acid, esters of this acid, or 2,5-di-tert-butyl-4-hydroxytoluene;
ii) lactams, such as &egr;-caprolactam, &dgr;-valerolactam, &ggr;-butyrolactam or &bgr;-propiolactam;
iii) active methylenic compounds, such as diethyl malonate, dimethyl malonate, ethyl or methyl acetoacetate, or acetylacetone;
iv) alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, n-amyl alcohol, t-amyl alcohol, lauryl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, methoxymethanol, glycolic acid, glycolic esters, lactic acid, lactic esters, methylolurea, methylolmelamine, diacetone alcohol, ethylenechlorohydrin, ethylenebromohydrin, 1,3-dichloro-2-propanol, 1,4-cyclohexyldi
Barghoorn Peter
Bendix Maximilian
Christie David
Mc Kee Graham Edmund
BASF - Aktiengesellschaft
Keil & Weinkauf
Niland Patrick D.
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