NO750074L - - Google Patents

Description

Grafted polymers, as well as methods for their production.

The present invention relates to bonded, phase-separated, self-curing, hydrophilic, thermoplastic grafting polymers or grafting polymers and their production. The hydrophilic copolymers or copolymers exhibit good wet strength, which• can be used in a number of different contexts, particularly within the biochemical area, e.g. contact lenses and artificial organs.

Extensive research and development has been devoted to obtaining polymers that exhibit sufficient wet strength to make them essentially water soluble. A type of hydrophilic polymers that exhibit improved wet strength is given, e.g. in US Patents 2,976,576 and 3,22o,96o and the "Journal of Applied Polymer Science!' vol. 9, pages 2425-2435 (1965). These polymers are prepared by the simultaneous polymerization of a water-soluble monoester of acrylic acid or methacrylic acid, in which the ester moiety contains at least one hydrophilic group such as a hydroxyl group, whereby the monomer is cross-linked as it is polymerized with a polyunsaturated crosslinker such as ethylene glycol dimethacrylate. The amount of such crosslinker is usually less than about 1 mol% of the monoester. Such polymerizations are generally carried out in the presence of a redox initiator.

Hydrophilic polymers with improved wet strength and derived from a polymer obtained by copolymerizing a water-soluble vinyl monomer containing at least one nitrogen atom with a small amount of a bifunctional monomer are also disclosed. ^These polymers have been suggested to be useful for various biomedical applications depending on their compatibility with body tissue and/or the mucosa. Some of these polymers are disclosed in US Patents 3,639,524 and 3,767,731. One of the factors necessary for the production of these previously known hydrophilic polymers with improved wet strength,

is the use of a small amount of a polyunsaturated crosslinker. As the amount of the crosslinking agent used is generally very small, the amount can only be varied slightly. Consequently, it is not possible to effectively determine or control the final properties of the therein hydrophilic polymer by varying the amount of crosslinking agent. Various attempts to

avoiding this problem is disclosed in U.S. Patent Nos. 3,503,942 and 3,758,448.

A prominent and ground-breaking discovery has now been made

for the production of chemically bonded, phase-separated, thermoplastic graft polymers. These copolymers are basically polymers of the physically cross-linked type (as opposed to the chemically cross-linked type) and are referred to as "self-curing" • or "self-reinforced" thermoplastic graft polymers. This phenomenon is caused by a controlled dispersion of a macromolecular side chain in a phase (domain or area),

within the polymer's basic structure or main chain polymer phase (matrix). Since all macromolecular monomer side chain regions are a complete part or are located between large segments of the polymer backbone, the resulting graft polymer possesses the properties of a crosslinked polymer if there is a large difference in the Tg or Tm value of the polymer backbone and the side chain segments. This is the case up to the temperature required to break apart the thermodynamic cross-linking in the dispersed phase. In order for the dispersed phase regions in the graft polymer to produce the desired cross-linked or "self-curing" effect, it is important that the ■ macromolecular monomers, which comprise the dispersed phase areas, essentially have the same molecular weight, i.e. the macromolecular monomers must have a Mw/Mn ratio that is not significantly above approx.

1.1. Macromolecular monomers that have a wider molecular weight distribution, i.e. a ratio greater than approx. 1.5 or 2, common polymer species of very low molecular weight have a "copolymeric" effect on the basic structure of the polymer and polymers of very high molecular weight that form a second dispersed phase or domain, or region with a size different from the primary dispersed the phase. The end result is an opaque polymer of lower quality with respect to the desired physical properties

properties that the backbone or main chain polymer exhibits.

The present invention relates to chemically bound, phase-separated self-cured, hydrophilic, thermoplastic graft polymers, which are water-insoluble as well as swellable in water. These new copolymers consist of a copolymer of at least one hydrophilic (water-soluble), ethylenically unsaturated monomer or mixtures thereof (or compounds which have been rendered hydrophilic and at least one copolymerizable, hydrophobic, macromolecular monomer exhibiting a copolymerizable end group, which is copolymerizable with said hydrophilic monomer based on the relative reactivity ratios in the respective copolymerizable parts, whereby said copolymerizable, hydrophobic, macromolecular monomer is characterized by having an essentially uniform molecular weight distribution, so that the ratio Mw/Mn is not significantly above around 1.1 and is further characterized by the fact that it has a molecular

weight of at least approx. 2 ooo.

The new copolymers according to the present invention are dispersible and swellable in water and find use in a number of different applications, such as suspension stabilizers, flocculants

agents, hydrogels (ie biomedical hydrogels such as contact lenses, artificial organs, etc.) industrial thickeners, ion exchange resins and drilling muds. The new copolymers have the ability to give many products moisture absorption and water permeability (applicable in dialysis tubes) as well as antistatic properties.

The present invention is specifically aimed at a

chemically bonded, phase separated, self-curing, hydrophilic,. thermoplastic graft polymer consisting of a copolymer of: 1. at least one copolymerizable, normally hydrophobic macromolecular

monomer somm mainly exhibits uniform molecular weight distribution, and

2.. at least one hydrophilic (water-soluble), copolymerizable co-

monomer or compound which has been made hydrophilic and which forms the polymeric basic structure or main chain in said copolymer, whereby said copolymerizable, normal hydrophobic macro

molecular monomers form linear polymer side chains of said grafting polymer, in which: a) the basic polymer structure of the grafting polymer consists of polymerized units of said copolymerizable comonomers, whereby said copolymerizable comonomers

is at least one ethylenically unsaturated monomer of a hydrophilic

or water-soluble compound and mixtures thereof,

b) the graft polymer's linear polymer side chains essentially consist of a polymerized, hydrophobic macromolecular

monomer, whereby said hydrophobic macromolecular monomer comprises a linear polymer or copolymer which exhibits a molecular weight of at least approx. 2ooo and which exhibits an essentially uniform molecular weight distribution so that the ratio Mw/Mn is not significantly above approx. 1.1, whereby said macromolecular monomer is further characterized in that it has no more than one copolymerisable part per linear polymer or copolymer chain, whereby said copolymerization occurs between the copolymerizable end group of said hydrophobic macromolecular monomer and said copolymerizable hydrophilic co-monomers, and

c) the linear polymer side chains of the graft polymer, which are copolymerized into the copolymer backbone, are separated

of at least approx. 2o uninterrupted repeating monomer units in said hydrophilic polymer basic structure, whereby the distribution of the side chains along the basic structure and the copolymerization is regulated by the reactivity ratio between the copolymerizable end group on said hydrophobic macromolecular monomer and said copolymerizable hydrophilic comonomer.

The graft polymers according to the present invention assume a T-type structure, when only one side chain is copolymerized to the hydrophilic copolymer basic structure or main chain. However, when more than one side chain is copolymerized to the hydrophilic basic structure polymer, the graft polymer can be characterized as having a comb-type structure which is visualized in the following way:

wherein "a" represents a substantially linear, normally hydrophobic polymer or co-polymer with uniform molecular weight distribution and with a sufficient molecular weight so that the physical properties of at least one of the substantially linear hydrophobic polymers appear,

"b" represents a reacted and copolymerized end group that is chemically bound to the side chain, "a" that is completely copolymerized to the backbone polymer, and "c" is the hydrophilic backbone polymer exhibiting uninterrupted segments of sufficient molecular weight so that the physical properties of the hydrophilic polymer appears.

The main chain or basic structure of the graft polymer according to the present invention suitably contains at least approx. 2o uninterrupted repeating - monomer units in each segment and preferably at least approx. 3o uninterrupted repeating monomer units in each segment. However, it has been shown that at least approx. loo uninterrupted repeating : j monomer units in each segment exhibit particularly undesirable physical properties. It has been found that this condition gives a graft polymer that possesses the properties of the hydrophilic basic structure polymer. The presence of segment containing at least approx. In other words, 2o uninterrupted repeating monomer units give the graft polymers the physical properties attributed to the polymer basic structure, such as water compatibility and water-swelling properties.

The basic structural polymer of the chemically bound, phase separated, self-curing, hydrophilic, thermoplastic graft polymers according to the present invention is derived from copolymerizable co-monomers of low molecular weight. These copolymerizable comonomers include polycarboxylic acids r/ their anhydrides and amides, polyisocyanates, organic epoxides, including thioepoxides, urea formaldehydes, siloxanes and ethylenically unsaturated monomers.

A particularly preferred group of copolymerizable comonomers includes the ethylenically unsaturated monomers, especially compounds

monomers-vinylidene type, i.e. monomers containing at least one

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vinylidene group, CH0 = G-. The compounds of the vinyl type, represented by the formula CH^ = CH, in which a hydrogen is 1 bonded to one of the free valences in the vinylidene group, are intended to fall within the general scope of the vinylidene compounds referred to above.

The co-polymerizable co-monomers which can be used in connection with the present invention are not limited to the exemplified compounds mentioned above. The only limitation for the particular comonomers to be used lies in their ability to copolymerize with the copolymerizable end groups in the side chain prepolymer by polymerization reactions under free radical, ionic, condensing or coordinating conditions (Ziegler catalysis or Ziegler-Natta catalysis).

The only limitation with regard to the low molecular weight co-monomers is that they have a functional part which makes them hydrophilic or a functional part which can be made hydrophilic by a subsequent reaction. A particularly preferred example of this later group of compounds includes vinyl esters such as vinyl acetate. The vinyl esters are copolymerized with the copolymerizable,

hydrophobic macromolecular monomer that has a copolymerizable double bond at its molecular chain end and after the copolymerization, the resulting graft polymer is saponified to render the polymer backbone hydrophilic. In other words, the basic polymer structure consists of polyvinyl alcohols.

As will be apparent from the description below

of the copolymerizable macromolecular monomers, the choice of the copolymerizable end groups includes any commercially available copolymerizable copolymer. The selection of respective copolymerizable end groups on the macromolecular monomer and the copolymerizable comonomer can therefore be made on the basis of relative reaction conditions under their respective reaction conditions suitable for copolymerization. By simply examining the reactivity in various kp monomer pairs in the literature, one can thus find the right end group on the macromolecular monomer and the co-polymerizable co-monomer. Preferably, the r-values for the respective copolymerizable parts are as close to unity as possible, as is well known to those skilled in the field of copolymerization

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merization. For example, an acrylate- or methacrylate-terminated macromolecular monomer is copolymerized with acrylates and methacrylates under conditions with free radicals in a manner determined by the respective reactivity ratios of the co-monomers.

As will be explained in the following description, the excellent combination of beneficial properties found in the graft polymers of the present invention is attributable to the large segments of uninterrupted hydrophilic copolymer backbones and the fully copolymerized linear hydrophobic polymer side chains of controlled molecular weight and small molecular weight distribution.

The term "linear" as defined above is used

in the conventional sense to refer to a polymer backbone or main chain that is free of cross-linking.

The term "hydrophilic" as defined above is used in the conventional sense to refer to a polymer or monomer substance or system that absorbs or adsorbs water.

The term "hydrophobic" as defined above is used in the conventional sense to refer to a polymeric substance that repels water.

The side chain polymers of substantially uniform molecular weight consist essentially of linear, hydrophobic polymers and copolymers prepared by anionic polymerization of any anionic polymerizable monomer or mixtures thereof that yield a polymer that is hydrophobic. The side chain polymer is distinctly different from the hydrophilic backbone polymer.

It is preferred that at least one segment in the side chain polymer of the grafting polymers according to the present invention has a molecular weight which is sufficient to produce the advantageous properties in the respective polymers. In other words, the physical properties of the side chain polymers are such that the glass transition temperature (Tg) will appear. The molecular weight in the polymer side chains is usually at least approx. 2ooo and preferably the polymers have a molecular weight within the interval from approx. 5ooo to approx. 5o.ooo. Particularly undesirable results have been obtained when the polymer side chains have a molecular weight within the interval from approx. lo.ooo to approx. 35.obo and more preferably within the interval from approx. 12.ooo to approx. 25.ooo.

In view of the unusual and improved physical properties possessed by the thermoplastic graft polymers of the present invention, it is believed that the monofunctionally bonded polymer side chains of substantially uniform molecular weight form what are known as "domains" or "regions"

("domains") which appear as dispersed small droplets which are

precipitated inside the matrix of the polymer base structure. As the domains or droplets are microscopic, they are generally below the wavelength of the backbone polymer.

The final graft polymer is clear or transparent. The hydrophobic polymer side chains, which provide the self-curing or self-reinforcing effect on the hydrophilic polymer backbone, improve the wet strength of the final polymer.

Preferred embodiments of the invention are described in the following:

Copolymerizable hydrophobic macromolecular monomers.

The hydrophobic polymer side chains of the above-mentioned chemically bonded, phase-separated, self-curing, hydrophilic graft polymers are preferably prepared by anionic polymerization of a polymerizable monomer or combination of monomers. In most cases, such monomers are made up of those having an olefin group such as the vinyl-containing compounds, although the olefin-containing monomers can be used in combination with epoxy- or thioepoxy-containing compounds.

The first step in preparing the copolymerizable hydrophobic macromolecular monomers is to prepare viable polymers. The viable polymers are conveniently prepared by contacting the monomer with an alkali metal hydrocarbon or alkoxide salt in the presence of an inert organic diluent or filler which does not participate in or interfere with the polymerization reaction.

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The monomers which are amenable or sensitive to anionic polymerization are well known and the present invention relates to

to use all anionically polymerisable monomers which give a mainly hydrophobic polymer with a molecular weight of at least approx. 2 ooo. Illustrative, non-limiting examples include aromatic vinyl compounds such as styrene, α-methylstyrene, vinyl toluene and isomers thereof, acenaphthalene, acrylonitrile and methactrylonitrile, organic isocyanates including lower alkyl, phenyl, lower alkylphenyl and halophenyl isocyanates , organic diisocyanates including lower alkylene, phenylene and tolylene diisocyanates, lower alkyl and allyl acrylates and methacrylates, including methyl, t-butyl acrylates and methacrylates, lower olefins such as ethylene, propylene, butylene, isobutylene, pentene , hexene, etc, vinyl esters of aliphatic carboxylic acids such as vinyl acetate, vinyl propionate, vinyl octoate, vinyl oleate, vinyl stearate, vinyl benzoate, vinyl lower alkyl ethers, conjugated dienes including isoprene and butadiene. The term "lower" is used above to denote organic groups containing eight or four carbon atoms.

The preferred olefinic monomers suitable for the preparation of the hydrophobic macromolecular monomers are the conjugated dienes containing 4-12 carbon atoms per molecule and the vinyl-substituted aromatic hydrocarbons containing up to approx. 12 carbon atoms. Particularly preferred monomers include styrene, α-methylstyrene, butadiene and isoprene.

Many other monomers suitable for the preparation of the side chains by anionic polymerization are those listed in "Macro-molecular Reviews", vol. 2, pages 74-83, Interscience Publishers, Inc. (1967), under the section headed "Monomers Polymerized by Anionic Initiators", to which content the

refer here.

The initiators for these anionic polymerizations are made up of any alkali metal hydrocarbons and alkoxide salts which give one monofunctional viable polymer, i.e. only one of the polymers contains a reactive anion. The catalysts which have proved suitable include the hydrocarbons of lithium, sodium or potassium according to the formula RMe, in which Me is an alkali metal such as sodium, lithium or potassium and R represents a hydrocarbon radical, for example an alkyl radical containing | up to about 20 carbon atoms or more and preferably up to approx. 8 carbon atoms, an aryl radical, an alkaryl radical or an aralkyl radical. Illustrative alkali metal hydrocarbons include ethyl sodium, n-propyl sodium, n-butyl potassium, n-octyl potassium, phenyl sodium, ethyl lithium, sec-butyl lithium-t-butyl lithium and 2-ethylhexyl lithium. Sec-butyllithium is the preferred initiator, because it has a rapid initiation, which is important in the production of polymers with a small molecular weight distribution. It is preferred to use the alkali metal salts of tertiary alcohols, such as potassium t-butyl alkoxylate, when the polymerizing monomers have a nitrile or carbonyl functional group.

The alkali metal hydrocarbons and alkoxylates are either available commercially or can be prepared by known methods, for example by allowing a halogen hydrocarbon, halogen benzene or alcohol to react with it. the appropriate alkali metal.

An inert solvent is usually used to support heat transfer and proper mixing of initiator and monomer. The hydrocarbon and ethers are the preferred solvents. Solvents useful in the anionic polymerization process include the aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, t-butylbenzene, etc. Also suitable are the saturated aliphatic and cycloaliphatic hydrocarbons such as n-hexane, n-heptane, n-octane , cyclohexane, etc. In addition to these, aliphatic and cyclic ether solvents can be used, for example dimethyl ether, diethyl ether, dibutyl ether, tetrahydrofuran, dioxane, anisole, tetrahydropyran, diglyme, glyme, etc. The polymerization rates are faster in ether solvents than in hydrocarbon solvents, and small amounts of ether in the hydrocarbon solvents increase the polymerization rates .

The amount of initiator is an important factor in anionic polymerization because it determines the molecular weight of the viable polymer. If a small proportion of initiator is used in relation to the amount of monomer, the molecular weight in the viable polymer will be greater than if a large proportion of initiator is used. Generally, it is advisable to add the initiator dropwise to the monomer (when this is the chosen order of addition) as long as the characteristic color of the organic anion is present and then add the calculated amount of initiator for the desired molecular weight. The initial dropwise additions serve to magnify impurities and thus provide better control of the polymerization.

In order to produce a polymer with a small molecular weight distribution, it is usually preferred to introduce all reactive species into the system at the same time. In this technique, polymer growth occurs by consistent addition of monomer at the same rate to an active end group, without a chain transfer or chain termination reaction. When this is done, the molecular weight in the polymer is regulated by the ratio between monomer and initiator, as can be seen from the following table:

As can be seen from the above formula, high concentrations of the initiator lead to the formation of polymers with a low molecular weight, while low concentrations of the initiator lead to the production of polymers with a high molecular weight.

The concentration of monomer charged to the reaction vessel can vary within wide limits and is limited by the ability of the reaction equipment to remove the heat of polymerization and properly mix the resulting viscous solutions of the viable polymer. Concentrations of monomers as high as 50% by weight or higher, based on the weight of the reaction mixture, can be used. However, the preferred monomer concentration is from approx. 5% to approx. 25% to achieve the right mix.

As can be seen from the above formula and the aforementioned limitations on the concentration of the monomer, the initiator concentration is critical, but can be varied according to the desired molecular weight of the viable polymer and the relative concentration of the monomer. The initiator concentration can generally range from approx. o,ool to approx. o.l mol active alkali metal per mol monomer, or higher. The concentration of the!<i>initiator is preferably from approx. o,ol to approx. o,oo4 mol of active alkali metal per moles of monomer.

The polymerization temperature depends on the monomer. Generally, the reaction can be carried out at temperatures ranging from approx. -loo°C up to approx. 100°C. When using aliphatic fillers and hydrocarbon fillers, the preferred temperature range is from approx. -lo°C to approx. 100°C. With ethers as solvent, the preferred temperature range is from approx. -loo°C to approx. 100°C. The polymerization of styrene is usually carried out at temperatures slightly above room temperature and the polymerization of α-methylstyrene is preferably carried out at lower temperatures, e.g.

-8o°C.

The preparation of the living or viable polymer can be carried out by adding a solution of the alkali metal hydrocarbon initiator in an inert organic solvent to a mixture of monomer and diluent or inactive filler at the desired polymerization temperature, after which the mixture is allowed to stand with or without agitation until the polymerization is finished. An alternative method of preparation is to add monomer to a solution of the catalyst in the diluent at the desired polymerization temperature at the same rate as it is polymerized. In each method, the monomer is quantitatively transferred or converted into a viable polymer as long as the system remains free of contaminants that inactivate the anionic species. As pointed out above, however, it is important to quickly add all the reactive components together to ensure the formation of an even or uniform molecular weight distribution in the polymer.

The anionic polymerization must be carried out under carefully controlled conditions to exclude substances that interfere with the catalytic effect in the catalyst or initiator. Such contaminants are, for example, water, acid, carbon dioxide, etc. The polymerization is thus usually carried out in dry equipment using anhydrous reagents and in an atmosphere of an inert gas, such as e.g. nitrogen, helium, argon, methane and the like.

The viable polymers, as described above, are amenable to further reactions including further polymerization. If such additional monomers, such as e.g. styrene is added to the viable polymer, polymerization begins again and the chain grows until there is no more monomer styrene left. If, alternatively, an anionically polymerizable monomer of a different kind is added, such as e.g. butadiene or ethylene oxide, the viable polymer described above initiates the polymerization of butadiene or ethylene oxide and the final viable polymer obtained consists of a polystyrene segment and a polybutadiene or polyoxyethylene segment.

A hydrophobic diblock or diblock copolymer can be prepared by bringing the first viable or active polymer, e.g. an active polymer of an aromatic vinyl compound, such as e.g. active polystyrene or active poly-(α-methylstyrene), in contact with another anionic polymerizable monomer, e.g.

the conjugated diene, such as e.g. butadiene or isoprene. In this way, an active disegment polymer is obtained which can be terminated by means of the methods used in the application of the present invention. By using this technique, an active disegment polymer with the following formula can be obtained:

wherein A is a polymer segment of an aromatic vinyl compound and,

B is a polymer segment of a conjugated diene. Copolymerizable macromolecular monomers having a disegment structure are described in US Patent Application No. 347,116, to which content reference is made herein.

As stated above, the active polymers used in the present invention are characterized by a relatively homogeneous or uniform molecular weight, i.e. the distribution of the molecular weights in the mixture of active polymers that is formed is quite narrow. This constitutes a marked contrast to the typical polymer, where the molecular weight distribution is very broad. The difference in the molecular weight distribution is particularly evident in an analysis of the partial permeation chromatogram for commercial polystyrene (Dow 666u) which is produced by polymerization with free

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radicals and polystyrene which is produced by the anionic polymerization method used in the application of the present invention. The active polymers thus produced according to the present invention are characterized by having an Mw/Mn ratio that is not significantly above approx. 1,1,

where Hw is the average molecular weight. for the active polymer and Mn is the number average molecular weight for the active polymer as determined by common analytical techniques such as e.g. gel permeation chromatography (GPC).

The active polymers specified herein are terminated by reaction with a ralogen-containing compound which also contains a polymerisable part, such as e.g. an olefin group or an epoxy or thioepoxy group. Suitable halogen-containing end-capping agents include: vinyl halogen alkyl ethers in which the alkyl groups contain six or fewer carbon atoms, such as e.g. methyl, ethyl, propyl, butyl, isobutyl, sec-butyl, amyl or hexyl, vinyl esters or haloalkanoic acids in which the alkanoic acid contains six or fewer carbon atoms, such as e.g. acetic acid, propionic acid, succinic acid, valeric acid or caproic acid, olefinic halides with six or fewer carbon atoms, such as e.g. vinyl halide, allyl halide, methallyl halide, 6-halo-1-hexene, etc, halides of dienes such as e.g. 2-halomethyl-1,3-butadiene, epihalohydrins, acrylyl and methacrylyl halides, haloalkylmaleic anhydrides, haloalkylmaleic esters, vinylhaloalkylsilanes, vinylhaloaryls, and vinylhaloalkylaryls, such as e.g. vinyl benzyl chloride (VBC, haloalkyl norbornenes, such as e.g. bromethylnorbornenes, bromonorbornenes and epoxy compounds such as e.g. ethylene or propylene oxide, The halogen group can be chlorine, fluorine, bromine or iodine and preferably

is it chlorine. Anhydrides of compounds having an olefin group or an epoxy or thioepoxy group can also be used,

such as e.g. malic anhydride, acrylic or methacrylic anhydride.

Termination of the active polymer is accomplished simply

by adding the terminating agent to the solution of active polymer at the temperature at which the active polymer is produced. The reaction is immediate and the yield is theoretical. A small molar excess of the terminating agent in relation to \

the amount of anionic initiator can be used, even if the reaction proceeds on a mole-to-mole basis. j

Termination can be carried out in any suitable inert solvent. It is usually advisable to utilize the same solvent system as is used in the preparation of the active polymer. A preferred embodiment of the invention consists in carrying out the termination reaction in a hydrocarbon solution rather than in polar solvents of the ether type, such as e.g. tetrahydrofuran. It has been shown that the hydrocarbon solvents, such as e.g. the aromatic hydrocarbons, saturated aliphatic and cycloaliphatic hydrocarbons, give several differences in the reaction conditions and the . the resulting products. The termination reaction can, for example, be carried out at higher temperatures with a hydrocarbon solvent in contrast to the ether solvents.

Due to the nature of the active polymer and the monomer from which it is prepared and due to the nature of the breeding agent, in some cases certain harmful side reactions occur which result in impure product. For example, the carbon anions in some active polymers tend to react with functional groups or any active hydrogens in the terminating agent. Thus gives, for example, acrylyl or methacrylyl chloride, while

they function as termination agents depending on the presence of chlorine atoms in their structure, also a carbonyl group in the terminated polymer chain, and this carbonyl group can form a center for attack by another highly reactive viable or active polymer. In each case, the resulting polymer has twice the . the expected molecular weight or contains some chlorine, indicating that some of the active polymer has been terminated by reaction with another active polymer or with one of the active hydrocarbons in the acrylyl or methacrylyl chloride.

It has been discovered that one way to overcome the above problem is to make the reactive carbon atoms less sensitive or susceptible to reaction with the functional groups or any active hydrogens in a terminating agent. A preferred method of making the active polymer less susceptible to the adverse reaction is to "protect"

the highly reactive active polymer with a smaller

in reactive reagent. Examples of preferred protecting agents include the lower alkylene oxides, i.e. those having eight or fewer carbon atoms, such as e.g. ethylene and propylene oxide, diphenylethylene, etc. The protected reaction

yields a product which still constitutes a viable or active polymer, but yields a pure product upon subsequent reaction with a capping agent containing a functional group or active hydrogen.

It has been found that diphenylethylene is an excellent protective or encapsulating agent when such terminating agents as e.g. vinyl chloroalkanoates are used.

A particularly preferred protective agent is an alkylene oxide, such as e.g. ethylene oxide. It reacts with the active polymer while dissolving its oxirane ring. In the following, it is explained

in a typical way the protected or encapsulated reaction and according to this example is shown the reaction between ethylene oxide as a protecting agent with an active polymer prepared by polymerization of styrene with sec-butyllithium as initiator:

The protected reaction is carried out simply by adding the protective and encapsulating reagent to the active polymer at polymerization temperatures, like the termination reaction. The reaction occurs immediately. As is the case with the termination reaction, a small molar excess of the protective reaction agent can be used in relation to the amount of initiator. The reaction occurs on a mole-for-mole basis.

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It should be understood that when a large molar excess of alkylene oxide is reacted with the active polymer, an active polymer is formed which has two polymer segments. A typical example with a polystyrene segment and a polyalkylene segment is explained as follows:

where x is a positive integer.

Each of them. the ethylene oxide encapsulated polymers described above

can be easily end-capped with a compound containing a moiety reactive with the anion in the protected polymer and a polymerizable end group including the following typical compounds: acrylyl chloride, methacrylyl chloride, vinyl-2-chloroethyl ether, vinyl chloroacetate, chloromethylmaleic anhydride and its esters, maleic anhydride (gives half-esters of maleic acid with subsequent protonation with water), allyl and methallyl chloride and vinyl benzyl chloride.

The reaction between the above-described protected active polymers with either acrylyl or methacrylyl chloride can be visualized by,-

where n is a positive integer of approx. at least 5o,

x is either 0 or a positive integer and R 4 is either hydrogen or methyl.

When an epihalohydrin is used as the end terminating reagent, the resulting polymer contains a terminal epoxy group. This terminal epoxy group can itself be used as the polymerizable group such as e.g. during manufacture

of a graft polymer with polypropylene oxide as the main chain or backbone, or it can be converted to various other useful polymerizable end groups by any of several known reactions.

As an embodiment of the invention, the terminating active polymer, which contains an epoxy or thioepoxy end group, can be reacted with a polymerizable carboxylic acid halide, such as e.g. acrylic acid, methacrylic acid or maleic acid halide, to form a (3-hydroxyalkyl acrylate ester, -methacrylate ester or -maleic ester as the polymerizable portion of the polymer with the substantially uniform molecular weight. The same polymerizable esters can be prepared from the terminal epoxy polymer by first converting the epoxy group to corresponding glycol by heating the polymer with aqueous sodium hydroxide followed by conventional esterification of the glycol end group with the appropriate polymerizable carboxylic acid or acid halide.

The resulting glycol obtained by the water hydrolysis of the epoxy group in the presence of a base can be converted into a copolymer by reaction with a high molecular weight dicarboxylic acid, which can be prepared e.g. by polymerization of a glycol or diamine with a molar excess of phthalic anhydride, maleic anhydride, succinic anhydride or the like. These reactions can be modified to obtain a polystyrene segment and a polyamide (nylon) segment. The glycol-terminated polymer can also be reacted with a diisocyanate to form a polyurethane. The diisocyanate can e.g. constitute the reaction product of a polyethylene glycol having an average molecular weight of

4oo with a molar excess of phenylenediisocyanate.

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According to another embodiment of the invention is copolymerized

J an organic epoxide with an end polymer containing an epoxy or thioepoxy end group. The graft polymer that is obtained is characterized by a basic structure or main chain that exhibits uninterrupted segments of at least approx. 2o and preferably at least approx. 3o repeating units of the organic epoxide. Preferred organic epoxides include ethylene oxide, cyclohexene epoxide and styrene oxide, ie those having eight or fewer carbon atoms. By simply performing hydrolysis, the backbone polymer can be rendered hydrophilic.

If one wishes to isolate and further purify the macromolecular monomer from the solvent from which it is produced, one can use any of the known techniques utilized by the person skilled in the field of polymer material recovery. These techniques include (1) solvent-non-solvent precipitation, (2) solvent drift in an aqueous medium, (3) solvent drift, such as e.g. by vacuum roll drying, spray drying, freeze drying, and (4) steam jet coagulation.

Isolation and recovery of the macromolecular monomer is not a critical feature of the invention. In the work itself, the macromolecular monomer need not be extracted at all. Stated another way, macromolecular monomer, once formed, can be charged with the appropriate monomer and polymerization catalyst to perform graft polymerization in the same system in which the macromolecular monomer was prepared, provided that the solvent and materials in the reaction vessel for its preparation the macromolecular monomer does not poison the catalyst or adversely affect the graft polymerization process. A well-considered choice of solvent and cleaning of the reaction vessel during the production of the macromolecular monomer can thus finally result in large savings during the production of graft polymerization according to the present invention.

As pointed out above, the macromolecular monomers,

which eventually become side chains in the graft polymer by being completely polymerized to basic structure polymers, exhibit

in a small molecular weight distribution. Methods for determining the molecular weight distribution in polymers, such as the macromolecular monomers, are known in the art. By using these known methods, the weight average molecular weight (Mw) and number average molecular weight (Mn) can be determined and the molecular weight distribution (Mw/Mn) of the macromolecular monomer can be determined. The macromolecular monomers must have a molecular weight distribution according to Poisson or be practically monodisperse in order to have the highest degree of functionality, i.e. the ratio Mw/Mn must not be significantly above approx. 1.1. The ratio Mw/Mn in the new macromolecular monomers is preferably less than approx. 1.1. The macromolecular monomers according to the present invention have the previously mentioned narrow molecular weight distribution and purity, thanks to the above-described method for their production. It is thus important that the sequence of the steps in the preparation of the macromolecular monomers is considered in order to obtain optimal results with regard to advantageous and beneficial properties of the graft polymers.

As can be seen from the above description is represented

the hydrophobic copolymerizable macromolecular monomers referred to according to the present invention, generally of the following structural formula:

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wherein I is the residue of the monofunctional anionic initiator, P-^ is at least one anionic polymerized monomer,

?2 is at least one anionic polymerized monomer which is that which or differs from P^,

R is either hydrogen or lower alkyl,

R' is either hydrogen or

wherein X is either hydrogen, lower alkyl or a monovalent metal,

n is a positive integer of at least approx. 2o,

m is either 0 or a positive integer, whereby the sum of n and m is such that the molecular weight of the macromolecular monomer is at least approx. 2ooo and preferably 5ooo to approx. 5o.ooo, o, q, r and s are either 0 or 1, and

p is either 0 or a positive integer within the interval from 1 to approx. 8 with the proviso that when o and p are 1, q is 0, r is 0 or 1, s is 0 or 1, and t is 0, when o is 0, p may be a positive integer and q, r, s and t can be 0 or 1, when o, q, r, s, and t are 0, p is a positive integer, and s can be 0 or 1, and

u and v are either 0 or 1, with the proviso that when u is 1,

is v 0 and when v is 1, u is 0,

whereby said copolymerizable macromolecular monomer is distinguished by the fact that it exhibits an essentially homogeneous or uniform molecular weight distribution, so that its ratio Mw/Mn is not significantly above approx. 1.1, where Mw is the weight average molecular weight in the monomer and Mn is the number average molecular weight in the monomer.

As previously mentioned, P₁ and P₂ are preferably polymers of aromatic vinyl compounds and conjugated dienes.

Copolymerizable hydrophilic (water-soluble) compounds.

The copolymerizable co-monomers which are suitable for obtaining the hydrophilic polymer basic structure of the graft polymer or the graft polymer according to the present invention must be water-soluble or have the ability to be made water-

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soluble after the copolymerization. These compounds must have the ability to copolymerize into a water-soluble material or one that can be made water-soluble. The term "water-soluble" is used here to include those compositions in which at least approx. 10% by weight and preferably at least 30% by weight are uniformly miscible in water at room temperature. Suitable copolymerizable monomers, which are intended to be used in the preparation of the hydrophilic polymer backbone in the graft polymer according to the present invention, include:

acrylic acid and methacrylic acid,

water-soluble monoesters of acrylic acid and methacrylic acid in which the ester part contains at least one hydrophilic group such as a hydroxy group, i.e. hydroxy-lower-alkyl acrylates and -methacrylates, of which the following are typical examples:

2-hydroxyethyl acrylate,

2-hydroxyethyl methacrylate,

2-hydroxypropyl acrylate,

2- hydroxypropyl methacrylate,

3- hydroxypropyl acrylate,

3-hydroxypropyl methacrylate,

diethylene glycol monomethacrylate,

diethylene glycol monoacrylate,

dipropylene glycol monomethacrylate, and

dipropylene glycol monoacrylate,

water-soluble vinyl monomers that have at least one nitrogen atom in the molecule, examples of which follow:

acrylamide,

methacrylamide,

methylacrylamide,

methylImethacrylamide,

diacetoneacrylamide,

N-methylacrylamide,

N-ethylacrylamide,

N-Hydroxyethylacrylamide,

N,N-disubstituted acrylamides such as N,N-dimethylacrylamide, N,N-diethylacrylamide, N-ethylmethylacrylamide, N,N-dimethylol-acrylamide and N,N-dihydroxyethylacrylamide, heterocyclic nitrogen-containing compounds such as N-pyrrolidone, N-vinylpiperidone , N-acryloylpyrriblidone, N-acryloylpiperidine and N-acryloylmorpholene,

cationic functional monomers can also be used, e.g.

vinylpyridine quaternary ammonium salts and dimethylaminoethyl methacrylate quaternary ammonium salts and compounds known under the trade name "Sipomer Q-1".

A particularly preferred class of compositions includes those capable of being rendered hydrophilic in a subsequent polymer reaction. For example, vinyl esters of carboxylic acid, such as vinyl formate, vinyl acetate, vinyl monochloroacetate and vinyl butyrate, can be copolymerized with the copolymerizable macromolecular monomers described above and, after the copolymerization reaction, the polymer basic structure containing repeating monomeric units of these vinyl esters of carboxylic acids can be made hydrophilic by hydrolysis to the resulting polyvinyl alcohol.

In other words, the basic polymer structure consists of a polyvinyl alcohol.

The hydrophilic monomers described above or those which are rendered hydrophilic by a later reaction can be used individually or in combination or as an intermediate product with other copolymerisable co-monomers. The copolymerizable monomers used in admixture or in combination with the hydrophilic monomers or those which can be rendered hydrophilic may be any ethylenically unsaturated monomer which may include a combination of hydrophilic monomers or a hydrophobic monomer and the "hydrophobic copolymerizable macromolecular monomer". Suitable hydrophobic copolymerizable monomers which may be interpolymerized with the above-described "hydrophobic copolymerizable macromolecular monomers" and the above-described "hydrophilic copolymerizable comonomers" include alkyl acrylates and methacrylates, e.g. methyl acrylate or methacrylate, ethyl acrylate or methacrylate, propyl acrylate or methacrylate, butyl acrylate or methacrylate, whereby butyl acrylate is preferred. Other suitable hydrophobic copolymerizable comonomers include vinyl chloride, vinylidene chloride, acrylonitrile, methacrylonitrile, vinylidene cyanide, vinyl acetate, vinyl propionate and vinyl aromatic compounds such as styrene and α-methylstyrene and maleic anhydride.

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The preferred classes of co-monomers which are useful

in the preparation of the hydrophilic polymer base structure in the j graft polymer according to the present invention, the monoesters of either acrylic acid and/or methacrylic acid and a polyhydric alcohol, such as 2-hydroxyethyl acrylate and -methacrylate, include the N,N-disubstituted acrylamides, such as N,N-dimethylacrylamide, especially when it is used in combination with butyl acrylate as another co-monomer, and vinyl esters of monocarboxylic acids such as vinyl acetate, which are saponified with an alkali with a subsequent copolymerization reaction.

The aforementioned "hydrophobic copolymerizable macromolecular monomers" which copolymerize with the copolymerizable co-monomer forming the hydrophilic copolymer backbone are present in amounts ranging from about 1% by weight to approx. 95% by weight, based on the copolymerizable co-monomer, which forms the hydrophilic polymer backbone. Stated differently, the chemically bonded, phase-separated, thermoplastic graft polymers having hydrophilic polymer backbones consist of (1) from about 1% by weight to approx. 95% by weight

of the copolymerizable hydrophobic macromolecular monomer having a narrow molecular weight distribution, and (2) from ca. 99% by weight to approx. 5% by weight of the copolymerizable co-monomer which forms the hydrophilic polymer basic structure. The grafting polymer preferably contains up to approx. 60% by weight and more preferably from approx. 2% by weight to approx. 40% by weight of the hydrophobic macromolecular monomer described above to achieve the final mechanical holding strength or strength in the polymer.

The copolymerization of the copolymerizable hydrophobic macromolecular monomer and the copolymerizable comonomer forming the hydrophilic polymer backbone of the graft polymer (and optionally a small amount of the appropriate comonomer or modifying monomer, as is sometimes indicated in the art), can be carried out by solution polymerization, emulsion polymerization, block or bulk polymerization, suspension polymerization and non-aqueous suspension polymerization.

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It is usually desirable, after the copolymerization reaction is completed, to remove any copolymerizable hydrophobic macromolecular monomer that has remained unreacted in the polymerization system. The removal of the macromolecular monomer can be done by any suitable means such as by solvent extraction.

If desired, especially in the case of mass polymerization,

the copolymerization can be carried out in a shaped form such as a contact lens form. In such a case, a prenitrating agent can be added to the copolymerization reaction to further improve the wet strength properties of the graft polymer. Suitable crosslinking agents for this purpose include ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, diethylene glycol dimethacrylate, divinylbenzene and N,N-methylene bis-methacrylamide. The amount of crosslinking agent used usually depends on the degree of cross-linking desired. Appropriate amounts of crosslinking agent can range from approx. o, 1% by weight to approx. 2% by weight or usually less than approx. 1 mol% based on the weight of the monomer that forms the hydrophilic polymer basic structure.

If a polymerization catalyst is used for copolymerization, a polymerization medium suitable for the catalyst should be used. For example, oil- or solvent-soluble peroxides, such as benzoyl peroxide, are usually effective when the copolymerizable hydrophobic macromolecular monomer is copolymerized with an ethylenically unsaturated comonomer in bulk, in solution in an organic solvent, such as benzene, cyclohexane, toluene, xylene, etc, or in aqueous suspensions. Water-soluble peroxides, such as e.g. sodium, potassium, lithium and ammonium persulfates, etc., are useful in aqueous suspension and emulsion systems. In the copolymerization of many of the copolymerizable hydrophobic macromolecular monomers, such as those with an ethylenically unsaturated end group and a polystyrene, polyisoprene or polybutadiene repeating unit, an emulsifier or dispersant can be used in an aqueous suspension system. In these systems, particular advantages can be obtained by dissolving the water-insoluble polymerizable macromolecular monomer in a small amount of a suitable solvent, such as a hydrogen-carbon. In this new technique, the co-monomer I is copolymerized with the polymerizable macromolecular monomer in the solvent in an aqueous system that surrounds the solvent-polymer system. The polymerization catalyst is selected so that it becomes soluble in the organic phase of the polymerization system.

The polymerization catalyst used can be any of the catalysts which. are suitable in the polymerization of compounds containing an ethylenic ring (provided the above criteria are met) and are preferably made by four-radical catalysts. Of particular interest are such catalysts as azobisisobutyronitrile and peroxide catalysts. Some examples of suitable peroxide catalysts include hydrogen peroxide, benzoyl peroxide, tert-butyl peroctoate, phthalic peroxide, succinic peroxide, benzoyl acetic peroxide, coconut oil peroxide, lauric peroxide, stearic peroxide, maleic peroxide, tert-butyl hydroperoxide, di-tert-butyl peroxide and the like.

The preferred catalyst is one which is active at moderately low temperatures such as approx. 45 - 85°C.

Besides the polymerization catalysts with free radicals, the catalysts can include such materials which primarily polymerize by opening the epoxide group, such as e.g. the epoxy-terminated copolymerizable hydrophobic macromolecular monomer. Such catalysts include p-toluenesulfonic acid, sulfuric acid, phosphoric acid, aluminum chloride, stannous chloride, ferric chloride, boron trifluoride, boron trifluoride-ethyl ether complex and iodine. It may be desirable to use a multi-stage polymerization process.

The amount of catalyst used depends on the type of catalyst system used and is usually from approx. o,l to approx. lo parts by weight per loo parts of the co-monomer mixture and is preferably from approx. o, 1 - approx. 1 part by weight per loo parts of the co-monomer mixture.

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The copolymerization is generally carried out at a temperature of approx. room temperature to approx. 165°C. However, it is usually preferred to initiate the polymerization at a relatively low temperature, such as from about. 4o°C to approx. 85°C and then increase the temperature to approx. 9o - approx. 165°C, as the reaction continues and preferably after most of the reaction has been completed. The most preferred initial temperature range for the polymerization is between approx. 45 and 7o°C. Usually, the polymerization is carried out under gas pressure in a closed reaction vessel. However, any suitable means or means may be used to prevent significant evaporation of any of the monomers.

The copolymerization is generally finished within approx. 4 to approx.

48 hours and preferably finished within approx. 6 to approx. 24 hours. It should be understood that time and temperature are inversely related to each other, i.e. a temperature used at the upper part of the temperature range results in polymerization processes that may be completed near the lower part of the time interval.

After the copolymerization, the graft polymer can be post-cured,

if desired, with the help of a suitable means. Depending on the self-reinforcing and self-hardening effect in the grafting polymer according to the present invention, however, such post-hardening is generally not necessary, with the exception of such applications where extreme holding strength is required. In those cases where a post-hardening reaction is desired, this can be carried out in a form or stop form which corresponds to the general or exact shape and/or size of the desired products. After the polymer is finished, including any post-curing, a solid, hard and clear copolymer is obtained.

The fabricated products can then be swollen in a suitable liquid until equilibrium is achieved or until a hydrogel is obtained containing the desired amount of liquid, such as aqueous liquid. In addition to this, it should be stated that the hydrogels can be obtained by swelling the polymers according to the present invention with water-soluble swelling agents instead of aqueous solutions. Some examples of water-soluble bulking agents include ethylene glycol, the liquid polyethylene glycols, the glycols of lactic acid, formamide, dimethylformamide, dimethylsulfoxide and the like, in

The copolymers according to the present invention can, besides

to be shaped in situ, processed by molding, strand pressing or spraying. It is also intended to be within the scope of the present invention that the copolymer can be coated or coated with other substrate or substrate materials. In this case, the graft polymers according to the present inventor Ise are particularly useful, as they contain both hydrophilic and hydrophobic groups. One or the other of these groups or both may be compatible or compatible with the coated substrate.

The copolymerizable or reactive end group of the hydrophobic macromolecular monomer, which is copolymerized with the second monomer, is specifically selected based on the relative reactivity ratios of the second comonomer selected to form the hydrophilic polymer backbone or backbone. The present invention thus relates to a means or method for controlling or regulating the structure of the graft polymer. More specifically, the control of the structure of the graft polymer can be achieved by one or all of the following ways: 1) by determining the reactivity ratio between the copolymerizable hydrophobic macromolecular monomer and the other monomer and the copolymerization reaction, a pure graft polymer can be produced, which is free from contamination by homopolymers, 2 ) by controlling the monomer addition rates during the copolymerization of the copolymerizable hydrophobic macromolecular monomer and the second co-monomer, the distance between the side chains in the polymer structure can be regulated, 3) the size of the graft chain can be determined and regulated during the anionic polymerization step in the preparation of the copolymerizable hydrophobic macromolecular monomer.

I It will be obvious to those skilled in the art that, ;

with the right choice of the end capping agent, all copolymerization mechanisms can be used in the production of the controlled j phase-separated graft polymers.

The reactivity ratio, r^, can be assessed from a sample with relatively low turnover by a simple experiment with. copolymerization. The value of this addition with a predeterminable and controllable reactivity for the copolymerizable hydrophobic macromolecular monomer can thereby be determined. It has been shown that the reactivity for commercial monomers together with the copolymerizable hydrophobic macromolecular monomers according to the present invention with different end groups corresponds to the values available in the literature for the reactivity ratio for r^.

By following the procedures outlined above, graft polymer is produced which exhibits distinctive or unique combinations of properties. These unique combinations of properties are made possible by the novel method of preparation described herein which conditions the compatibility of the otherwise incompatible polymer segments. These incompatible segments separate into phases of their own kind. In the case of the present graft polymer which has a hydrophilic polymer base structure and a hydrophilic polymer side chain, separate phases of the respective polymers are thus formed. The product morphology consists of a hydrophobic domain or region dispersed in a hydrophilic polymer matrix. The hydrophobic domains are connected by means of water-soluble chain segments. The hydrophobic domains.: act as crosslinks and give the water-swollen polymer backbone wet strength. The degree of swelling in water can be controlled by the amount and molecular weight of the copolymerized hydrophobic macromolecular monomer and by the composition of the water-soluble or hydrophilic polymer backbone. One type of example includes a composition in which the hydrophilic backbone or main chain consists of a 5/95-acrylic acid/ethyl acrylate to 10/0-acrylic acid/ethyl acrylate, and a methacrylate-terminated polystyrene having a molecular weight in the range of about lo.ooo to approx. 35.ooo and a weight within the range from - 2o% to approx. 80% of the total product. This product can be swelled with water to form a usable hydrogel.

i As the graft polymer consists of hydrophobic and hydrophilic segments, they are particularly useful as protective colloids in or suspension stabilizers for pigment, polymer suspensions, emulsions, etc. They are also useful in protective coatings and paints, where the color rheology can be controlled, or in adhesives, where they the hydrophobic polymer side chains can serve a dual role as a stabilizer and promoter in adhesion.

The new graft polymers according to the present invention

are also usable as flocculants, especially when the hydrophilic polymer structure contains cationic monomer functional groups. These types of basic structure polymer material are also usable as • pulp additive. The copolymers can also be used as a thickener or antifoam agent. The dual nature of the new copolymers according to the present invention also makes them usable as a wetting agent and connecting agent for hydrophilic surfaces in adhesive and bonding applications.

The high wet strength of the new copolymers according to the invention makes the polymer compositions according to the invention usable as water-permeable membranes, sponges, hydrogels, ion exchange resins, conductive polymers, etc. Compositions with moisture permeability and moisture absorbability

ability can also be produced by incorporating the copolymer according to the present invention in films, etc. When the copolymerizable hydrophobic macromolecular monomer is used in lower concentrations, the products exhibit antistatic properties, especially if cationic functional parts are present in the hydrophilic polymer basic structure. The copolymers according to the present invention can also be used to be deposited on packaging film to obtain antistatic properties and for a fog-free hydrophilic surface.

The graft polymers that contain both the hydrophilic and hydrophobic polymer chains in a single molecule have an increased effect on thickening in contrast to conventional industrial thickeners.

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The dissolution properties of the graft polymers according to the present invention differ from randomly selected copolymers. While in the case of a randomly selected copolymer with dissolution properties it can be considered that there should be a new polymer composed of a single monomer unit, the graft polymers according to the present invention contain elements with the properties found in the constituent homopolymer chains. As soon as the interaction between the two dissimilar polymer chains becomes dominant, the norm is that there will be incompatibility and phase separation.

When e.g. a grafting polymer consisting of water-soluble

and water-insoluble component chains are added to composite latex, the exchange action takes place between polymer thickener and latex particles, or pigment, clays, and the molecules in the polymer thickener break up. As two homopoly tag chains are incompatible, the hydrophobic chains join together to form a microgel particle. The flocculation progresses rapidly to form large aggregates and finally a network is formed where all the particles are bound together by the latex thickener's molecules and where microgel particles of the hydrophobic part of the thickener's molecules act as cross-linking points. When using the polymer materials as industrial thickeners, flocculants, etc., the most effective structures are block or graft polymers containing two incompatible homopolymer chains, i.e. one is hydrophilic and the other hydrophobic. The hydrophilic part of the molecules loosens the hydrophobic part to make the whole molecule water (or alkali) soluble. However, when the thickeners are added to compound latex, the interaction between the thickener and latex particles, clay, pigment, and the grafting polymer reduces the water solubility. The hydrophobic part of the molecule becomes water insoluble and aggregates to form a microgel, as it is incompatible with the other part of the molecule.

The new graft polymers according to the present invention

is also suitable for forming a carrier for medically active substances and for natural and synthetic aroma components, fragrances, spices, food colors, leavening agents,

color components and the like. Various additives can thus be incorporated into the grafting polymer according to the present invention in the manner indicated in American patent no. 3,520,949, to whose contents reference is hereby made.

The invention shall be illustrated by the following examples. In all cases, all materials must be clean and care must be taken to keep the reacted mixtures dry and free from contaminants. All parts and percentages are expressed by weight, if nothing else is expressly stated.

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EXAMPLE 1

Production of polystyrene finished with allyl chloride. A stainless steel reactor is charged with 76.56 parts of A.C.S.-grade (thiphene-free) benzene, which has been desiccated using Linde-type molecular sieves and calcium hydride. The reactor is heated to 4o°C and 0.15 parts diphenylethylene is added to the reactor by means of an injection syringe. A 12.1% solution of sec-butyllithium. in hexane is added to the reactor portionwise until a permanent orange-yellow color is maintained, at which time an additional 0.885 parts (1.67 mol) of sec-butyllithium solution is added followed by the addition of 22.7^ parts (218 mol) of styrene over a period of 44 my. The reactor temperature is maintained at 36 - 42°C. The viable or active polystyrene is terminated by adding 0.127 parts of allyl chloride to the reaction mixture. The resulting polymer is precipitated by the addition of the α-olefin-terminated polystyrene-benzene solution to methanol, whereupon the polymer is precipitated in the solution. The α-olefin-terminated polystyrene is dried in a dryer with an air-circulating atmosphere at 4o - 45°C and then in a fluidized substrate to remove trace amounts of methanol. The methanol content after purification is lo ppm. The molecular weight of the polymer, as determined by membrane phase osmometry, is 15.4oo (theoretically 13.ooo) and the molecular weight distribution is me narrow, i.e. the ratio Mw/Mn is less than 1.05. The macromolecular monomer has the following structural formula: ; in which n has such a value that the molecular weight of the polymer is 15.4oo. ;EXAMPLE 2;Preparation of poly-(α-methylstyrene) terminated with allyl chloride. A reading of 472 g (4.0 mol) of α-methylstyrene in 2500 ml of tetrahydrofuran is treated dropwise with a 12% solution of n-butyllithium in hexane until a light red color is retained. A further 30 ml (0.383 mol) of this n-butyllithium solution is added, resulting in the appearance of a clear red color. The temperature of the mixture is then lowered to -8o°C and. after 3o min. at this temperature, 4.5 g (0.06 mol) of allyl chloride are added. The red color disappears almost immediately, indicating that the active polymer is terminated. The obtained colorless solution is poured into methanol to precipitate the α-olefin-terminated poly(α-methylstyrene) which, by vapor phase osmometry, is found to have a number average molecular weight of 11.ooo (theoretically 12.3oo) and the molecular weight distribution is very narrow, i.e. .,the ratio Mw/Mn is less than l.o5. The produced macromolecular monomer has the following structural formula: ; in which n has such a value that the molecular weight of the polymer becomes ll.ooo. ;EXAMPLE 3;Production of polystyrene finished with vinyl chloroacetate.;A solution of 1 drop of diphenylethylene in 25oo ml of cyclohexane;at 4o°C is treated in portions with a 12% solution of sec-butyllithium in cyclohexane until a pale red color remains , at which time a further 18 ml (0.024 mol) of sec-butyllithium is added followed by the addition of 312 g (3.0 mol) of styrene,<p>the temperature of the polymerization mixture is maintained at 4o°C for 3o min., after which the active polystyrene be encapsulated or protected by treatment with 6 ml (o.o5 mol) vinyl chloroacetate. The resulting polymer is precipitated by adding the cyclohexane solution to methanol and the polymer is separated by filtration. Its number average molecular weight, as determined by vapor phase osmometry, is 12.ooo (theoretically 13,265); and the molecular weight distribution is very narrow, i.e. Mw/Mn is less than 1.06. The produced macromolecular monomer has the following structural formula: ;i ; in which n has such a value that • the molecular weight of the polymer is 12,000. ;EXAMPLE 4;Preparation of poly-(α-methylstyrene) terminated with vinyl chloroacetate. A solution of 357 g (3.0 mol) of α-methylstyrene in 2.500 ml of tetrahydrofuran is treated dropwise with a 12% solution of t-butyllithium in pentane until a light red color remains. A further 15.0 ml (0.03 mol) of t-butyllithium solution is then added, resulting in the development of a clear red colour. The temperature of the mixture is then lowered to -8o°C and after 3o min. at this temperature, 5.6 ml of diphenylethylene are added. The resulting mixture is kept in 5.0 ml (0.04 mol) of vinyl chloroacetate and the poly-(α-methylstyrene) thus terminated is precipitated with methanol and separated by filtration. Its number average molecular weight, as determined by pond phase osmometry, is 14.28o (theoretical 12.065) and the molecular weight distribution is very narrow. The produced macromolecular monomer has the following structural formula: ; in which n has such a value that the molecular weight of the polymer is 14.28o. ;I ;I \ EXAMPLE 5 ;Production of polystyrene finished with vinyl-2-chloroethyl ether.';1 solution of 1 drop of diphenylethylene at 4o°C is treated in portions with a 12% solution of t-butyllithium in pentane to a light red color remains, at which point a further 30 ml (0.04 mol) of the t-butyllithium solution is added, followed by the addition of 312 g (3.0 mol) of styrene. The temperature of the polymerisation mixture is maintained at 4o°C for 3o min., after which the active polystyrene is finally terminated by treatment with 8 ml (0.08 mol) of vinyl-2-chloroethyl ether. The resulting polymer is precipitated by adding the benzene solution to methanol and the polymer is separated by filtration. Its number average molecular weight, as determined by vapor phase osmometry is 7.2oo (theoretical 7.87o) and the molecular weight distribution is very narrow, i.e. the ratio Mw/Mn is less than 1.06. The produced macromolecular monomer has the following structural formula: ; in which n has such a value that the molecular weight of the polymer is 7.2oo. ;EXAMPLE 6;A benzene solution of active polystyrene is prepared according to example 5 and is terminated by treatment with 10 g (0,10 mol) epichlorohydrin. The end-capped polystyrene obtained is precipitated with methanol and separated by filtration. Its molecular weight, as determined by vapor phase osmometry, is 8,660 (theoretical 7,757) and its molecular weight distribution is very narrow. The produced macromolecular monomer has the following structural formula: ; ; in which n has such a value that the molecular weight of the polymer is 8,660.; EXAMPLE 7; Production of polystyrene finished with methacrylyl chloride. A 12% solution of n-butyllithium in hexane is added dropwise to a solution of 0.2 ml of diphenylethylene in 2.500 ml of benzene until a light reddish-brown color remains. A further 24 ml (0.031 mol) of this n-butyllithium solution is added and then 416 g (4.0 mol) of styrene, resulting in the development of an orange color. A temperature of 4o°C is maintained at all times by external cooling and by controlling the rate at which the styrene is added. This temperature is maintained for a further 3o min after all the styrene has been added and is then lowered to 2o°C, after which. 4.4 g (0.1 mol) of ethylene oxide are added, which causes the solution to become colourless. The active polymer is terminated by reaction with 10 ml (0.1 mol) methacrylyl chloride. The resulting polymer has a number average molecular weight of 10,000 as determined by vapor phase osmometry. The macromolecular monomer has the following structural formula: ; where n has such a value that the molecular weight of the polymer becomes lo.000. ;i ;EXAMPLE 8;Production of polystyrene finished with methacrylyl chloride. A stainless steel reactor is charged with 121.12 liters of A.C.S.-grade (thiphene-free) benzene, which has been desiccated using Linde-type molecular sieves and calcium hydride. The reactor is heated to a temperature of between 38 - 40°C and 10 ml of diphenylethylene is added to the reactor using an injection syringe. An 11.4% solution of sec-butyllithium in hexane is added to the reactor in portions until a residual orange-yellow color is obtained (60 ml) at which time a further 1.562 kg of sec-butyllithium in hexane is added to the reactor followed by the addition of 37.455 kg of purified styrene; for a period of 1 hour and 4o min. The temperature of the reactor is kept at 38 - 4o°C. The active polystyrene is encapsulated or protected by the addition of 127.1 g of ethylene oxide and the reaction solution changes color from reddish orange to yellow. The resulting encapsulated active polystyrene is then reacted with 260 ml of methacrylyl chloride and the solution changes colour, so that a very pale yellow color is obtained. The methacrylate-terminated polystyrene is precipitated by adding the polymer benzene solution to methanol, after which the polymer is precipitated from the solution. The polymer is dried with an air-circulating atmosphere at 4o - 45°C; and then on a fluidized substrate for. to remove trace amounts of methanol. The polymer's molecular weight, as determined by membrane phase osmometry, is 13.4oo and the molecular weight distribution is very narrow, i.e. the ratio Mw/Mn is less than 1.05. ;EXAMPLE 9;Manufacture of polystyrene terminated with maleic anhydride.;A stainless steel reactor is charged with 2.5 liters of A.C.S.-grade benzene (thiphene-free), which had been desiccated by means of ;Linde-type molecular sieves and calcium hydride. The reactor was heated to 40°C and 0.2 ml of diphenylethylene was added to the reactor using an injection syringe. A 12.1% solution of sec-butyllithium in hexane is added to the reactor in portions until a permanent orange-yellow color (0.7 mL) is obtained, at which time an additional 22.3 mL of the sec-butyllithium solution is added followed by addn. of 421.7 g of styrene over a period of 16 min. The reactor temperature is kept at 4o - 45°C. 5 min. after all the styrene has been added, ethylene oxide is added intermittently from a bottle placed below the surface until the solution becomes water-clear. ;1 hour after all the ethylene oxide has been added, ;2o.55 ml of a solution of maleic anhydride and benzene (the maleic anhydride solution is prepared by dissolving 84 g of maleic anhydride in 55o g of purified benzene) is added to the encapsulated active polymer. 1 hour after the addition of the maleic anhydride solution, the reactor is emptied of its contents, which are then precipitated in methanol. The maleic acid half-ester terminated polystyrene had a molecular weight of approx. 14.ooo, as determined by gel permeation chromatography. The polymerizable macromolecular monomer has a structural formula according to the following: ; ; EXAMPLE 10; Preparation of polybutadiene terminated with allyl chloride. C.P.-quality 1,3-butadiene (99.0% purity) is condensed and collected in half-liter soda bottles. These bottles had been oven treated at 15o°C, nitrogen gas purged under cooling and encapsulated with a perforated metal crown cap using butyl rubber and polyethylene film inserts. These bottles containing the butadiene are stored at -lo°C; a nitrogen pressure head (lo psi) in a laboratory freezer for use. Hexane solvent is charged to the reactor and heated to 5o°C followed by the addition of 0.2 ml of diphenylethylene by means of a syringe. Sec-butyllithium is added dropwise by means of the sprayer to the reactor until the red diphenylethylene anion color remains for at least j ;I ;i lo - 15 min. The reactor temperature is lowered to 0°C and 328, and butadiene is charged to the polymerization reactor followed by the addition of 17.4 ml (0.02187 mol) of a 12% sec-butyllithium solution in hexane, after half of the butadiene charge has been fed to the reactor. The butadiene is polymerized for 18 hours in hexane at 5o°C. After the polymerization, portions of 4oo ml of the anionic polybutadiene solution are transferred into the reactor under nitrogen pressure in capped bottles. Allyl chloride (o.48 mL, o.oo588 mol) is injected into each bottle. Collect in a water bath at temperatures of 5o°C and 7o°C for a period of time that extends up to 24 hours. The samples in each of the bottles are interrupted with methanol and Ionol solution and analyzed by gel permeation chromatography. Each sample is water clear and the analyzes of the sample from the gel permeation chromatography reveal that each sample had a narrow molecular weight distribution. A number of comparison samples are prepared in the bottles, which samples came from the same mass of active polybutadiene and which were encapsulated with 2-chlorobutane (0.4 ml, 0.00376 mol) as end capping agent. The obtained polymers terminated with 2-chlorobutane were yellow in color and after standing for a period of 24 hours at 7o°C they proved to have a broad molecular weight distribution as evidenced by the sample from the gel permeation chromatography. It is clear that the reaction between 2-chlorobutane and anionic polybutadiene and the.. obtained reaction products differs from the reaction between allyl chloride and anionic polybutadiene and the* thereby obtained reaction products.

EXAMPLE 11

Production of polyisoprene finished with methacrylate.

A 4 liter glass bowl reactor of the Chemco type is charged with 2.5 1 of purified heptane, which had been dried using Linde type molecular sieves and calcium hydride, after which 0.2 ml of diphenylethylene as an indicator is added and the reactor is sterilized by the dropwise addition of tertiary butyllithium solution (12% in hexane) until the characteristic pale yellow color is obtained and remains. The reactor is heated to 4o° and 19.9 ml (o.o25 mol) of a 12% solution of tertiary butyllithium in hexane is injected into the reactor by means of an injection syringe followed by the addition of 331.4 g (4.86 mol) isoprene. The mixture is allowed to stand for 1 hour at 4o C and 0.13 mol of ethylene oxide is added to the reactor to encapsulate the active polyisoprene. The encapsulated active polyisoprene is kept at 4o°C for 4o min., after which o,o41

moles of methacrylyl chloride are charged to the reactor to terminate the encapsulated active polymer. The mixture is kept for 3o min.. at 4o°C, after which the heptane solvent is removed by vacuum extraction. Based on the sample from the gel permeation chromatography for polystyrene, the methacrylate-terminated polyisoprene exhibited a molecular weight of approx. lo.ooo (theoretically 13.oo). The methacrylate-terminated polyisoprene macromeloecular monomer has the following structural formula:

EXAMPLE 12

Production of polyisoprene terminated with α-olefin.

A 4 liter glass bowl reactor of the Chemco type is bet with 2.5

liters of purified heptane, which has been combined using Linde-type molecular sieves and calcium hydride, after which 0.2 ml of diphenylethylene as an indicator is added. The reactor and solvent are sterilized by the dropwise addition of tertiary butyllithium solution (12% in hexane) until the characteristic pale yellow color is obtained and remains. The reactor is heated to 40°C and 19.03 ml (0.02426 mol) of tertiary butyllithium solution is injected into the reactor by means of an injection syringe followed by the addition of 315.5 g (4.63 mol) of isoprene. The polymerization may take place at 5o°C

for 66 min. and at this point 2.0 mol (0.2451 mol) of allyl chloride is added to the active polyisoprene. The finished polyisoprene is kept at 5o° for 38 min., after which the polymer is removed from the reaction to be used in copolymerization reactions. The polymer is analyzed by gel permeation chromatography and showed a very narrow molecular weight distribution/ i.e.

a ratio Mw/Mn of less than approx. l,o6. The theoretical molecular weight of the polymer is 13.ooo. The polymerizable macromolecular

The monomer has the following structural formula:

EXAMPLE 13

Preparation of polystyrene macromolecular monomer encapsulated with butadiene and terminated with allyl chloride.

2.5 1 benzene (thiephen-free) is added to the reactor and heated to 4o°C. o.2 ml of diphenylethylene is added as an indicator and the reactor is sterilized by the dropwise addition of a 12% solution of sec-butyllithium until an orange-red color remains.

At this point, a further 18 ml (o.o24 mol) is added

of the sec-butyllithium solution (12% in hexane) followed by the addition of 416 g (4.0 mol) of styrene. The temperature of the polymerization mixture is maintained at 4o°C for 5 min. The active polystyrene is then encapsulated or protected with butadiene by bubbling butadiene gas into the reactor until the solution changes color from maroon to orange. The active polymer is terminated by treatment with 4.1 ml (0.05 mol) allyl chloride. The macromolecular monomer thus produced is precipitated with methanol and separated by filtration. Its number average molecular weight determined by gel permeation chromatography is 2 5.ooo (theoretical I8,000) and the molecular weight distribution is very narrow. The produced macromolecular monomer has the following structural formula:

where m is equal to 1 or 2.

EXAMPLE 14

Preparation of a graft polymer having hydrophilic poly- and acrylic acid polymer basic structure and hydrophobic polystyrene polymer side chains.

60g of a polystyrene finished with vinyl-2-chloroethyl ether like this

as prepared according to example 5 and which had a molecular weight of approx. 8,000 and a very narrow molecular weight distribution so that the ratio Mw/Mn is less than approx. l,o6, was dissolved in 24o g acrylic acid and 5o g tetrahydrofuran (THF) in a 2-liter plastic bottle. 500 g of additional THF was placed in the 2 liter plastic bottle and 0.6 g of benzoyl peroxide was then added. The bottle was heated to 65°C and the polymerization was allowed to proceed for 2 hours. After the polymerization, 300 g of distilled water was added to the plastic bottle and the tetrahydrofuran was distilled off. The aqueous copolymer system was then used as a latex thickener.

EXAMPLE 15

Preparation of a padding polymer having a hydrophilic polyacrylic acid polymer backbone and hydrophobic polystyrene polymer side chains.

4 g of tTriton-X-loo" were dissolved in 5oo g of distilled water and

placed in a Waririg type mixer. 30 g of tertiary butyl polystyrene vinyl ether prepared according to Example 5 was dissolved in 60 g of benzene and the solution was added to the Waring mixer containing the "Triton X-loo" solution under vigorous stirring to obtain a stable dispersion. The dispersion He was placed in a 2-liter plastic bottle, which was equipped with a stirrer and a shaker, and was purged with nitrogen for 1 hour. The vessel was heated to 65°C and 240 g of acrylic acid was added (pH was neutralized to 8.0 with ammonium hydroxide). 1 g of benzoyl peroxide was added to the plastic bottle and the polymerization was carried out at 69°C over the course of 3 hours. The polymer was recovered as in Example 14 for further calculation and testing as an industrial latex thickener.

EXAMPLE 16

Preparation of a graft polymer having hydrophilic polyacrylic acid polymer structure and hydrophobic polystyrene polymer side chains. 18 g of Triton X-405 (or 26 g of a 70% solid Triton X-405) was dissolved in 300 g of water and the pH was adjusted to 8 with ammonium hydroxide and the solution was placed in a tfaring mixer. 30 g of tertiary butyl polystyrene vinyl ether was prepared according to Example 5, was dissolved in 70 g of ethyl acrylate and the solution was added to the tfaring mixer containing the "Triton X-405" solution, under high shear stresses to prepare a stable dispersion. The dispersion is placed in a 2-liter plastic bottle, which was equipped with a stirrer and a dressing apparatus, and purged with nitrogen for one hour. The vessel was heated to 65°C and 0.1 g of ammonium persulfate was added. 200 g of ethyl acrylate and 2% ammonium persulfate solution were added to the polymerization vessel over a 3-hour period and the polymerization was carried out at 65°C - 67°C. The polymer backbone was made hydrophilic by hydrolyzing the acrylic acid ester groups with alkali under heat. The hydrophilic-hydrophobic polymer obtained was recovered in the manner described in the preceding examples.

EXAMPLE 17

Latex thickening of graft polymer having a hydrophilic polyacrylic acid polymer backbone and polystyrene polymer side chains. 3 graft polymers, which were composed of 80% polyacrylic acid polymer backbones and 20% polystyrene polymer side chains and which were prepared according to the previous example, were tested as latex thickeners. The size of the polystyrene side chain was as follows: Prove A (G30), Mn = 1.ooo, Prove B (G32), > Mn = 4,000, Prove C(G33), Mn = 8,000. The graft polymers were tested in the following way. To 3oo g of samples of "Wica-Latex'7o35" (5o% solids) 0.3 g, 0.6 g and 1.2 g of the hydrophilic graft polymer (calculated on solids) were added and the viscosity was measured using of a Brookfield LVT-Viscometer (spindle #3, 12 revolutions per minute). The result of this testing is shown in table 1 below.

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As can be seen from the above data, the graft polymers according to the present invention function as excellent thickeners for latexes due to the presence of both the hydrophilic and hydrophobic polymer segments. It is clear that the polymer side chains, which have a uniform molecular weight distribution, contribute to the overall ability to form a stable latex. It also appears that the polymer side chains with a higher molecular weight improve the overall thickening ability. This is because the polymer side chains at the higher molecular weights, i.e. above approx. 2.ooo, has the same properties as a polystyrene polymer and a better phase separation occurs when the polymer side chains have a higher molecular weight.

EXAMPLE 18

Preparation of graft polymerizate having a hydrophilic polyvinyl alcohol polymer backbone and hydrophobic polystyrene polymer side chains.

60g of the purified copolymerizable hydrophobic macromolecular monomer exhibiting a vinyl end group as prepared according to that given in Example 5 (the macromolecular monomer was prepared in the same way, with the exception that sec-butyllithium was used as initiator and the polymer had a molecular weight of 2.080 and a Mw/Mn ratio of less than about 1.1), was copolymerized with 240 g of vinyl acetate in benzene using benzoyl peroxide as catalyst. The thus produced polyvinyl acetate styrene graft polymer (G26) was hydrolyzed to polyvinyl alcohol-styrene graft poly-<1>

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merisate in a 5o/5o methanol/benzene mixture using sodium hydroxide as catalyst. The resulting polymer<1>was washed with methanol, vacuum dried and then extracted with benzene. Analyzes of the extracted copolymer showed that a copolymer had been formed. The saponified products were formed as a film to maintain their water resistance compared to commercially available polyvinyl alcohol. Each film was placed on glass and soaked in water at room temperature overnight. By simple visual observation, it became quite clear that the water resistance in the copolymers according to the present invention was improved to a large extent in relation to the water resistance in the control sample of polyvinyl alcohol.

EXAMPLE 19

Preparation of graft polymer which has a hydrophilic polyvinyl alcohol polymer basic structure and hydrophobic polystyrene polymer side chains.

A latex copolymerization reaction was carried out by adding 0.4 g of sodium dodecyl sulfate to 85 g of water with stirring. To this is added 15 g of the methacrylate-terminated polystyrene which was produced according to example 8, after which 30 g of vinyl acetate was added, 0.15 g of benzoyl peroxide was added and the polymerization was carried out for 6 hours at 4o - 5o°C. After the polymerization, the copolymer was stirred in 10 ml of methanol and 10 ml of sodium hydroxide was added to the solution over a period of 20 minutes. The solution was treated by reflux in lo min. and the polymer was washed twice with iso-propanol and dried at 70°C under vacuum. The solubility of the hydrolysed products was investigated using a range of different solvents. The copolymer was slightly soluble in DMSO, but insoluble in toluene, tetrahydrofuran>benzene and cresol. Films produced from the copolymer were transparent and exhibited good tensile strength and excellent wet strength.

EXAMPLE 2o

Preparation of copolymer having hydrophilic polyhydroxy-ethyl methacrylate polymer basic structure and hydrophobic polystyrene polymer side chains. 75 parts of a methacrylate-terminated polystyrene was prepared according to example 7 and showed a uniform or narrow molecular weight distribution, was mixed with 125 parts of hydroxyethyl methacrylate and the polymerization was initiated with 0.4 parts of tertiary butyl peroctoate as polymerization catalyst. The polymerization of the material was carried out by initially heating the mixture to approx. 5o°C for 8 hours. The polymerization was then terminated by heating for about 1 hour at 9o°C and then heating for a further 1 hour at 12o°C. After the polymerization was finished, a clear, firm and hard copolymer was obtained. The polymer was contacted with physiological saline until it reached an osmotic equilibrium state.

with the physiological saline solution. The hydrogel film thus obtained was clear, flexible and elastic.

EXAMPLE 21

Preparation of a graft polymer having a hydrophilic poly-(N,N-dimethylacrylamide) polymer backbone and hydrophobic polystyrene polymer side chains.

40 g of the purified highly functional methacrylate-terminated polystyrene was prepared according to Example 8 (molecular weight 13.400 and a Mw/Mn ratio of less than 1.05) and 60 g of N,N-dimethylacrylamide was dissolved in 150 g of benzene. The mixture

was mixed on a shaker to obtain a homogeneous solution. o.12 g of AIBN-(VAZO) polymerization initiator was added and the contents transferred to a 1 liter polymerization bottle, the contents were flushed with nitrogen and subsequently contained by further nitrogenation. The polymerization bottle was placed on a shaker in a water bath for 19.5 hours at 6o°C followed by a final polymerization temperature

o

at 85 C for 2 hours. The copolymer obtained was a clear, highly viscous liquid. 250 g of benzene was added to the viscous liquid copolymer to make it less viscous.

The weight of the solvent and the copolymer was 465 g, of which 20.9% were solids (95.4 g solids), giving a copolymer yield of 95.4%.

Films of the copolymer were formed by drawing the benzene polymer merisate solution onto glass slides using a drawing forceps.

i The films were optically clear. The coated disks were immersed in

in distilled water and the resulting wet films were tough and remained clear. The degree of swelling of the films was 2.2 g of water per g copolymer. The wetted films had a tensile strength of -. of o,o7o3 kp/cm 2 (87o psi) and an elongation capacity of loo%. The films were tested for water vapor transmission (WVT) using ASTM Test Method E96-63T.(B) and the wetted films' WVT values were 1.loo g/24 h/m 2 .

Analyzes of the copolymer by gel permeation chromatography showed that no unreacted hydrophobic macromolecular monomer was present. The fact that the copolymer did not dissolve when immersed in water and the high holding strength of the wetted films testifies that the hydrophobic polymer side chains functioned as physical cross-links to the normally water-soluble poly-(N,N-dimethylacrylamide).

The above copolymer was inverted in water and examined for water vapor transmission properties. The wetted copolymer film had a tfVT value of 2.ooo g/24 h/m , which highlights its utility as a semipermeable membrane.

EXAMPLE 22

Preparation of a graft polymer having a hydrophilic poly-(N,N-dimethylacrylamide) polymer backbone and hydrophobic polystyrene polymer side chains.

10 parts of a methacrylate-terminated polystyrene were prepared according to the method described in Example 8 (the methacrylate-terminated polystyrene had a molecular weight of 12.00 and a Mw/Mn ratio of less than about 1.06, as determined by analysis by gel permeation chromatography )

was dissolved in a mixture of 9o parts of N,N-dimethylacrylamide and 9oo parts of benzene. The mixture was placed on a shaker until a homogeneous solution was obtained. Next, 0.1 part AIBN is added and the solution is introduced into a 1-litre polymerization bottle and purged with nitrogen and sealed. After further purging the contained system with nitrogen, the polymerization mixture is placed on a shaker in a hot water bath at 67°C and the polymerization is allowed to proceed

for 12 hours. After the polymerization, the copolymer was recovered by precipitation in hexane followed by filtration and i

drying. The copolymer was a clear, viscous solution that exhibited excellent wet strength properties when immersed in water.

EXAMPLE 23

Preparation of a graft polymer having a hydrophilic poly-(N,N-dimethylacrylamide) polymer backbone and hydrophobic polystyrene polymer side chains.

lo parts of a methacrylate-terminated polystyrene produced according to the method described in example 8 (the methacrylate-terminated polystyrene had a molecular weight of 12.7oo and a Mw/Mn ratio of less than about 1.05 as determined by analyzes with gel permeation chromatography) were dissolved in 9o parts of N,N-dimethylacrylamide, 5 parts of calcium stearate were dispersed in the comonomer mixture and 200 parts of heptane and 1.1 part of AIBN were added to the comonomer mixture with rapid stirring. The system was placed in a 1-liter polymerization bottle, purged with nitrogen and sealed. The contained system is subjected to a further purge with nitrogen to purge the system. The polymerization is carried out by placing the polymerization bottle on a shaker in a hot water bath at 67°C and the polymerization is allowed to take place for 12 hours. The copolymer is obtained in the form of a fine powder and can be easily filtered and dried. The recovery of the copolymer was extremely successful due to the application of the non-aqueous emulsion polymerization technique. Analysis of the product by permeation chromatography showed that there was no unreacted methacryl-terminated polystruene present. The copolymer exhibited excellent wet strength when exposed in water. The copolymer was also useful in the preparation of a poly blend with polyvinyl chloride. In this way, various polyblends were prepared by dry mixing 40 - 60 parts by weight of the copolymer with 60 - 40 parts by weight of polyvinyl chlorides. The dry sheets were subjected to shear stress on a roller at elevated temperature to obtain films exhibiting excellent properties in the trace measure of water vapor transmission or transfer. For a further description of the method of mixing polymers of N,N-dialkylacrylamides with polyvinyl chloride resins, reference is made to US patent application No. 359,284, the contents of which are hereby referred to.

in

In the following, a specific example of a poly mixture is described. 33.3 parts of the copolymer described above is dry-blended with 70 parts polyvinyl chloride ("Vygen llo) and 70 parts dioctyl phthalate (DOP). The dry-blended mixture is placed on a rubber roller at a temperature of 147°C (3oo°F) under 8 min.

The mixed components melt very quickly and formed

a smooth, clear, transparent film. After the mixture was mixed and subjected to high shear stress, a film with a thickness of 0.0025 mm was examined for water vapor transmission and water absorption properties. The poly compound had a water vapor transmission of 2oo g/24 h/m 2 and absorbed 5.8% moisture for 18 hours at 85% relative humidity. As a comparison, a similar sheet of a homopolymer of N,N-dimethyl-acrylamide and the plasticized polymer of vinyl chloride was prepared, whereby this sheet exhibited a water vapor transfer rate of 75g/24 h/m and absorbed 4.5% moisture for 18 hours at 85% relative humidity. It is quite clear that, besides the improved physical properties, the hydrophobic polystyrene side chains improve the preparation of the poly blend and this is attributed to the solubility of the polystyrene side chains in the dioctyl phthalate.

In other words, the side chains improve the melt rheology given to the poly-(N,N-dimethylacrylamide) by these side chains.

EXAMPLE 2 4

Preparation of a graft terpolymer from a hydrophilic poly-(N,N-dimethylacrylamide)/butyl acrylate polymer backbone and hydrophobic polystyrene polymer side chains.

lo parts of a methacrylate-terminated macromolecular monomer was prepared according to Example 8 (the methacrylate-terminated polystyrene had a molecular weight of 2o.ooo and a Mw/Mn ratio of less than about 1.06, as determined by gel permeation chromatography) was dissolved in 85 g N,N-dimethylacrylamide using an air stirrer. 5 parts butyl acrylate, 5 parts calcium stearate and 0.1 part AIBN and 200 parts heptane were then added to the co-rhonomer mixture, which was then stirred and transferred to a 1 liter polymerization bottle, the polymerization mixture was purged with nitrogen and contained. The polymerization was carried out by placing the reaction flask on a shaker in a hot water bath at 67°C for 16 hours. The terpolymer was filtered and dried. The yield of terpolymer was 105 g - 100%

based on added "solid material".

EXAMPLE 2 5

Preparation of a graft terpolymer from a hydrophilic maleate half-ester polymer backbone and hydrophobic polystyrene polymer side chains.

A maleate half-ester of a metoxypolyethylene oxide ether with a molecular weight of 75o ("Carbowax 75o") was first prepared by condensing maleic anhydride with "Carbowax 75o". 7 parts of the "Carbowax 75o-maleate half-ester and 25o parts of isooctane ("Soltrol lo", Phillips Petroleum Company) were placed in a reaction vessel. The temperature of the reaction vessel was raised to

o

73 C and a co-monomer mixture of 135 parts of N,N-dimethylacrylamide and 7.5 parts of a maleate half-ester terminated polystyrene macromolecular monomer was added. (The maleate half-ester terminated polystyrene had been prepared according to the method described in Example 9. The polymer had a molecular weight of 7,000 and a Mw/Mn ratio of less than about 1.05, as determined by gel permeation chromatography). To the reaction vessel, which contained the polymerizable monomers, were then added 20 parts of a 20% solution of 53/47 N,N-dimethylacrylamide/lauryl methacrylate copolymer dispersion in isooctane and 0.3 parts of AIBN as polymerization initiator, which addition took place over a period of 5 hours, after which time additional isooctane was added. After polymerization for a further 12 hours, a fine dispersion of the terpolymer was recovered by filtration. The terpolymer had excellent wet strength when immersed in water.

EXAMPLE 26

Preparation of a copolymer of hydrophilic poly-(hydroxyethylmethacryl) polymer backbone and hydrophobic polyisoprene polymer side chains.

50 parts (based on solids, dry state) of the methacrylate terminated polyisoprene prepared according to Example 11

(the methacrylate-terminated polyisoprene had a molecular weight of 10.ooo and a Mw/Mn ratio of less than 1.1, as determined by gel permeation chromatography) in heptane was mixed with 10 parts hydroxyethyl methacrylate in a 1 liter polymerization reactor. The co-monomer mixture is purged with nitrogen and co-i

is polymerized by adding o.2 parts AIBN polymerization initiator at a temperature of 67°C over a period of time !

in 16 hours. The resulting copolymer was a clear,

viscous solution. The clear copolymer solution was placed in a mold and subjected to gamma radiation for 20 hours. The copolymer was then blotted in physiological saline. The wetted copolymer had excellent wet strength attributed to the fact that the hydrophilic backbone is held together by the hydrophobic side chains,

which are bound together by radiation cross-linking. The copolymer was thus reinforced by a cross-linked hydrophobic domain structure that was chemically bound to hydrophilic ones

matrix phases.

The hydrophilic-hydrophobic graft polymers according to the present invention exhibit unexpectedly improved physical properties (e.g. tensile strength, wet strength, elongation, etc.) when they are in their hydrated state. Generally, the hydrophilic polymers must be cross-linked with a chemical cross-linking agent to achieve their improved physical properties.

The new copolymers according to the present invention, however, provide in a unique or distinctive way a thermally labile physical crosslink, which serves to anchor the polymer structure and also provides a "filler effect" and thus increases the modulus and tensile strength in the final polymer. When the graft polymer is heated to a temperature higher than the Tg value of the polymer side chain (9o - loo°C for polystyrene), the domains become liquid and achieve plastic shape change or flow under pressure and are thus truly thermoplastic. When the graft polymer is cured, the domains form again and the graft polymer assumes the properties of a cross-linked hydrophilic polymer.

The addition of an aqueous liquid acts only as a plasticizer for the hydrophilic polymer, without dissolving the entire copolymer material. The graft polymers can be formed into hydrogels by immersion in an aqueous liquid (water or physiological salt, etc.). The amount of aqueous liquid can vary over a wide range depending on the composition of the graft polymer, i.e. the amount of polymer side chains in the graft polymer. in

Usually, the amount of the water-holding liquid is within the inter-

the election from approx. lo weight-% to approx. 95% by weight calculated on the graft polymer, preferably 45 - 80% by weight. Even when a higher content of aqueous liquids is found in the grafting polymer according to the present invention, they have the ability to retain their shape, which makes them usable in the production of contact lenses, body implants and the like. The formation of hydrogels by immersing the copolymer according to

lying invention in an aqueous liquid, causes the hydrogel to collect in the copolymer in the form of small droplets that fill microscopic pores or openings, which are distributed throughout the matrix in the hydrogel or the hydrogel's mechanical preservation is increased by the hydrophilic polymer's covalent forces held together by the the thermally labile crosslinks in the hydrophobic polymer side chains. The water can also, if desired, be removed from the graft polymer by subjecting the polymer material to pressure. After the pressure ceases, air cannot enter the openings and the total volume of the products remains smaller until they are placed in contact with water or an aqueous solution, whereupon they swell back to their original size and shape. The water is held in such a product partly by capillary action in the openings and partly because it forms a component of the hydrogel's colloidal system. Hereby, the hydrogels according to the present invention have absorbent properties which can be advantageously utilized for booklet compresses or layers such as e.g. by medical bandages. The products can also be used as an ultra-filtering semi-permeable membrane film. In the latter context, it may be appropriate to make the hydrophilic copolymer porous by using a leaching agent or raising agent which is incorporated into the polymer structure during the polymerization process or during a subsequent treatment.

Another unique modification of the present invention involves the preparation of hydrophilic-hydrophobic graft polymers as emulsions which are useful for coating or coating paper. These . copolymer includes a polyvinyl aromatic compound (eg, polystyrene) or polyvinyl aromatic compound/polybutadiene in a polyvinyl acetate polymer backbone. The following reactions characterize this unique modification for the production of emulsion graft polymer:

The graft polymer is initially produced by copoly-

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merize either the copolymerizable macromolecular monomer (a) or (b) with vinyl acetate under free radical conditions. The emulsion has excellent physical properties which are suitable for use in paper coating. It is e.g. It is known that polystyrene butadiene latex is used to a large extent in the paper industry as a pigment binder.

Although polyvinyl acetate latex has the better adhesion, whiteness and lower odor, its use has been limited due to its low wet nap strength and wet rubbing resistance. This is because polyvinyl acetate is more hydrophilic (the water strength of the vinyl acetate monomer is 2.8 g/loo g of water) compared to polystyrene-butadiene which is a hydrocarbon resin. Copolymeri-

sation of styrene with vinyl acetate is impossible because the r^ value for styrene is 0.01 and the r^ value for vinyl acetate is 55. By using the unique copolymerizable macromolecular monomers of the present invention, the properties of polyvinyl acetate and polystyrene can and polystyrene-butadiene combine to obtain the excellent adhesion and whiteness of polyvinyl acetate and the good wet nap strength and wet rub resistance of a polystyrene or polystyrene-butadiene latex.

A further unique aspect of the present invention lies

in producing paper additives for pulp addition from the copolymer. For example, the graft polymer according to example 18 can be treated with a cationic reagent to thereby obtain a wet end additive for pulp addition in papermaking. Such a method can be illustrated with the following reaction core starting from the products according to example 18:

The polymer described above is unique insofar as the phase separation of the polyvinyl alcohol segment increases both the wet strength and the dry strength of the paper containing the cationic graft polymer.

Although the invention has been described in connection with specific embodiments, it must be understood that further modifications can be made and the present description and patent claims are intended to cover any variations, applications or transformations of the invention that follow the general principles of the invention and the description and the patent claims thus include deviations from what has been described above, which fall within known or applicable adaptations within the area to which the invention belongs and which can be applied to the essential properties which have been described in the foregoing and which fall within the scope of the invention .

Claims (1)

1. Chemically bonded, phase-separated, self-curing, hydrophilic, thermoplastic graft polymer, characterized by 1) at least one copolymerizable normally hydrophobic macromolecular monomer, which has an essentially uniform molecular weight distribution, and 2) at least one hydrophilic (water-soluble) copolymerisable co-monomer or compound that has been made hydrophilic and which forms the basic polymer structure or main chain of the copolymer, which copolymerizable normally hydrophobic macromolecular monomers form unpaired polymer side chains in the graft polymer, whereby a) the polymer base structure of the graft polymer consists of polymerized units of said copolymerizable comonomers, which copolymerizable co-monomers make up at least one ethylenically unsaturated monomer of a hydrophilic or water-soluble compound and mixtures thereof or a compound that can be made hydrophilic or water-soluble, b) the linear polymer side chains of the graft polymer essentially consist of a polymerized hydrophobic macromolecular monomer, which hydrophobic macromolecular monomer comprises a linear polymer or copolymer that exhibits a molecular weight of at least approx. 2,000 and which has an essentially uniform molecular weight distribution so that its Mw/Mn ratio, as defined in the description, is not significantly above approx. 1,1, which macromolecular monomer is further characterized in that it has no more than one copolymerizable part per linear polymer or copolymer chain, which copolymerization takes place between the copolymerizable end group in said copolymerizable hydrophilic comonomers, and whereby c) the graft polymer's linear polymer side chains, which are copolymerized to the copolymer base structure, are separated by approx. 2o uninterrupted repeating monomer units of said polymer basic structure, in addition the distribution of the side chains along the basic structure and the copolymerization is regulated by the I reactivity ratio between the copolymerizable end group; in on said hydrophobic macromolecular monomer and said copolymerizable hydrophilic co-monomer. j 2. Graft polymer according to claim 1, characterized in that said copolymerizable co-monomers, which form said hydrophilic copolymer basic structure, are selected from a group consisting of acrylic acid and methacrylic acid. 3. Graft polymer according to claim 1, characterized in that said copolymerizable co-monomer, which forms said hydrophilic copolymer basic structure, is a monoester of either acrylic acid or methacrylic acid and a polyhydric alcohol. 4. Graft polymer according to claim 3, characterized in that said monoester is selected from a group consisting of 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate. 5. Graft polymer according to claim 1, characterized in that said copolymerizable co-monomer, which forms the hydrophilic copolymer basic structure, is a water-soluble vinyl monomer which has at least one nitrogen atom in the molecule. 6. Graft polymer according to claim 5, characterized in that said water-soluble vinyl monomer is N,N-dimethyl-acrylamide. 7. Graft polymer according to claim 6, characterized in that said water-soluble vinyl monomers are copolymerized in a mixture with butyl acrylate. 8. Graft polymer according to claim 1, characterized in that said normally hydrophobic macromolecular monomer, which is copolymerized with said copolymerizable co-monomer, which forms the hydrophilic copolymer basic structure, is derived from a monofunctional copolymerizable macromolecular monomer represented by the formula wherein R is lower alkyl, Z is a repeating monomer unit of a moiety selected from the group consisting of vinyl aromatic compounds having up to 12 carbon atoms and conjugated dienes having 4-8 carbon atoms and mixtures thereof, n is such a positive integer that the molecular weight of the polymer is in the range from approx. 5.ooo to approx. 5o.ooo, and in which X is a polymerizable end group selected from the group consisting of wherein R is either hydrogen or lower alkyl. 9. Grafting polymer according to claim 8, characterized in that said copolymerizable hydrophobic macromolecular monomer is represented by the structural formula: wherein R is lower alkyl, R' is either hydrogen or lower alkyl and n is a positive integer which has such a value that the molecular weight of the polymer is within the range from about 5,000 to about 5o.ooo. laughed. Grafting polymer according to claim 8, characterized in that said copolymerizable hydrophobic macromolecular monomer is represented by the structural formula: in which n is such a positive integer that the molecular weight of the polymer is within the range from approx. 5.ooo to approx. 5o.ooo. 11. Graft polymer according to claim 8, characterized in that said copolymerizable hydrophobic macromolecular ■ monomer is represented by the structural formula: n in which n is such a positive integer that the molecular weight of the polymer is within the range from approx. 5.ooo to approx. 5o.ooo. 12. Graft polymer according to claim 1, characterized in that said copolymerizable co-monomer, which forms the hydrophilic copolymer basic structure, is a vinyl ester of a monocarboxylic acid which is made hydrophilic by saponification of said vinyl ester after the copolymerization. 13. Graft polymer according to claim 12, characterized in that said vinyl ester is vinyl acetate. 14. Method for producing a chemically bound, phase-separated, self-curing, hydrophilic, thermoplastic graft polymer according to one of claims 1-13, characterized by the following steps: 1) copolymerization of: a) at least one copolymerisable normally hydrophobic macromolecular monomer, comprising a linear polymer or copolymer having a molecular weight of at least approx. 2.ooo and an essentially uniform molecular weight distribution so that its Mw/Mn ratio is not significantly above approx. 1,1, which macromolecular monomer is further characterized by the fact that it has no more than one copolymerisable part per linear polymer or copolymer chain, which copolymerizable part is found at the end of the chain, and b) at least one copolymerizable co-monomer, which copolymerizable co-monomer forms the basic polymer structure or main chain of the graft polymer and which copolymerizable normally hydrophobic macromolecular monomer forms the linear polymer side chains in the graft polymer, whereby the linear polymer side chains of the graft polymer are copolymerized into the basic structure polymer via the polymerizable end group on said macro- In molecular monomers, whereby said copolymerizable co-monomer unit in the basic structure consists of a polymerized vinyl ester of a monocarboxylic acid and the linear polymer side chains of the graft polymer, which are copolymerized to the copolymer basic structure, are separated by at least approx. 2o uninterrupted repeating monomer units in said basic structure polymer, moreover, the copolymerization and the distribution of the side chains along the basic structure are regulated by the relative reactivity ratios between the copolymerizable end group on said hydrophobic macromolecular monomer and said copolymerizable comonomer, and 2) saponification of the resulting copolymer to thereby obtain said chemically bound, phase-separated, self-curing, hydrophilic, thermoplastic graft polymer. 15. Method according to claim 14, characterized in that said vinyl ester of a monocarboxylic acid is vinyl acetate. 16. Method according to claim 15, characterized in that the produced polyvinyl alcohol copolymer basic structure is reacted with a cationic reagent. 17. Grafting polymer according to claim 1, characterized in that said graft polymer is in the form of a hydrogel containing from approx. lo weight-% to approx. 95% by weight of an aqueous liquid calculated on the weight of said grafting polymer. 18. Grafting polymer according to claim 17, characterized in that the graft polymer hydrogel is a porous membrane.