WO2001057097A1

WO2001057097A1 - Non-aqueous polymer suspensions having a highly dilatant flow effect

Info

Publication number: WO2001057097A1
Application number: PCT/EP2001/000699
Authority: WO
Inventors: Wolfgang Podszun; Juan Gonzales-Blanco; David Bryan Harrison; Kamelia Karlou-Eyrisch; Jens Sicking; Kadir Oezbayram
Original assignee: Bayer Aktiengesellschaft
Priority date: 2000-02-04
Filing date: 2001-01-23
Publication date: 2001-08-09
Also published as: AU2001239225A1; DE10005036A1

Abstract

The invention relates to non-aqueous polymer suspensions having a highly dilatant flow effect.The invention also relates to the production and use thereof.

Description

Non-aqueous polymer suspensions with a strongly dilated flow behavior

The invention relates to non-aqueous polymer suspensions with a strongly dilated flow behavior, their preparation and use.

In the literature, the terms dilatancy and shear thickening are often defined for the increase in viscosity from a critical shear rate. According to the British Standard of Rheological Nomenclature, dilatancy is defined as an increase in volume with increasing deformation and shear thickening as an increase in viscosity with increasing shear rate (Barnes, Journal of Rheology, 33 (2), 329-366 (1989). In the present application, dilatantem Flow behavior can be understood as a sharp increase in viscosity at a defined shear rate.

Examples of the use of systems with a dilated flow behavior are, for example, shock and vibration dampers, torque transmitters in clutches, all-wheel drives, particularly in the automotive sector, thickeners, damping elements for leisure equipment and leisure shoes (e.g. sports shoe soles for long distance running, ski shoe pads) and for the filling of orthopedic cushions ,

US-A-3 728 295 describes an aqueous latex with a dilatant flow behavior which is obtained by emulsion polymerization. This latex can be used for coating products.

EP-A-043 464 describes a process for the preparation of copolymers having a narrow particle size distribution and a dilatant flow behavior. The copolymers are prepared by emulsion copolymerization, in which the monomers are copolymerized in an aqueous emulsion with simultaneous agglomeration with only partial fusion of the polymer particles initially formed. The polymer particles initially formed have a particle diameter from 5 to 200 nm. During agglomeration, they form irregular particles with a rough surface, which have a particle diameter of 380 to 640 nm. A disadvantage of these copolymer dispersions is the high temperature dependence of the critical shear rate. This temperature dependence is particularly unfavorable when used in the automotive sector.

EP-A-174 566 describes suspensions of carboxyl group-containing copolymers of monoolefinically unsaturated monomers with strongly dilated flow behavior, in which the temperature dependence of the critical shear rate through a content of 0.1 to 30% by weight of oxides, hydroxides, and carbona - th and / or water-soluble salts of 1- or 2-valent metals is reduced. The suspensions contain agglomerated copolymer particles with a very uneven and irregular surface, which were formed during the production by emulsion polymerization by partially melting the initially formed copolymer particles with a diameter of 50 to 200 nm. The copolymer particles have a rough surface and they have a diameter of 330 to 600 nm. This process gives systems which often have a low long-term stability of the viscosity increase, which is not sufficient for many technical applications. Due to the high water content of these suspensions, their use at elevated temperatures is technically complex.

DE 39 17 506 describes fluid friction clutches for the automatic transmission and deactivation of torque transmission.

US-A-5 037 880 describes an aqueous dilatant copolymer dispersion which can be used, for example, as a torque transmitter. The copolymer is produced by emulsion copolymerization and then freeze-dried. The dried powder is redispersed in an aqueous dispersant in which lithium chloride and lithium hydroxide have been dissolved. The copolymer particles have a particle size of 250 to 500 nm. This process gives

Suspensions that only have a dilatant flow at higher shear rates show behavior and therefore cannot be used for some technical applications.

The use of inorganic particles for the production of materials with dilatant flow behavior has been described in many different ways, for example in EP-A-

727 478, JP 91 00 110, and JP 10 152 669 dilatant liquids which are present as a colloidal solution at low shear stress and as a gel at high shear stress and contain dispersed inorganic particles. The inorganic particles are oxides or nitrides of Si, Al, Mg or Zr. These dilated liquids have an undesirable abrasiveness and show limited settling stability.

The abrasiveness when using these dilated liquids in damping or control devices can lead to premature wear or to a limited lifespan of this device.

There was therefore a need for systems with a highly dilated flow behavior which

Not have disadvantages of the prior art.

Non-aqueous polymer suspensions with a strongly dilated flow behavior have now been found, which are characterized in that they

a) a spherical, largely monodisperse vinyl polymer,

b) a carrier liquid,

and if necessary

c) an additive

contain. The non-aqueous polymer suspensions according to the invention are characterized above all by the fact that they have a high dilatant effect even at low shear rates. They are particularly well suited for damping elements such as shock absorbers and vibration dampers, as well as in medical pillows, sports equipment and sports shoes. Another advantage of the suspensions according to the invention is their high stability. The polymer suspensions according to the invention are stable even after prolonged storage at higher temperatures of 200 to 300 ° C., so that they have a constant property profile even after prolonged temperature loads.

Component (a)

The spherical, largely monodisperse vinyl polymer preferably has an average particle size of 0.8 to 10 μm, preferably 1 to 5 μm.

Microscopic image analysis was used to determine the average particle size (0) and the particle size distribution of the spherical, largely monodisperse vinyl polymer. As a measure of the width of the particle size distribution of the vinyl copolymers, the ratio of the average of the volume distribution (D) and the average of the number distribution (Dz) was formed.

Largely monodisperse in the sense of the invention means D _v / D _z 1,2 1.2, preferably D / D _z 1,1 1.1, particularly preferably D / D _z 1,0 1.05.

For the purposes of the invention, the term vinyl polymer is understood to mean homopolymers and copolymers of vinyl monomers. Vinyl monomers are, for example, compounds from the group consisting of straight-chain, branched or cyclic olefins, vinyl aromatics, unsaturated carboxylic acid or carboxylic acid derivatives and vinyl derivatives, it being possible for all of the compounds mentioned to be unsubstituted or substituted. Preferred vinyl monomers are, for example, styrene, .alpha.-methylstyrene, chlorostyrene, acrylic acid, acrylic acid esters, such as, for example, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, dodecyl acrylate, methacrylic acid, methacrylic acid esters, such as, for example, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-isopropyl methacrylate, Butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate,

Decyl methacrylate, dodecyl methacrylate, stearyl methacrylate, acrylonitrile, methacrylonitrile, methacrylamide and vinyl acetate.

The spherical, largely monodisperse vinyl polymer is preferably crosslinked. Crosslinking is generally present when the vinyl polymer contains polymerized units of bifunctional or multifunctional vinyl monomers as crosslinking agents. Preferred crosslinkers are divinylbenzene, tri-allyl isocyanurate, allyl methacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, methylene bisacrylamide, trimethylolpropane triacrylate and pentaerythriol tetraacrylate.

Particularly preferred spherical, largely monodisperse vinyl polymers are crosslinked via Si-O-Si groups. These polymers can be produced by copolymerizing vinyl monomers with polymerizable vinylsilanes with hydrolyzable groups. During or after the copolymerization, the copolymerized silanes can be converted by hydrolysis into silanols which form Si-O-Si segments as crosslinking sites with elimination of water.

Very particularly preferred spherical largely monodisperse vinyl polymers contain, based on the largely monodisperse vinyl polymer

a) 50-99% by weight polymerized vinyl monomers and b) 1-50% by weight polymerized vinylsilane monomers

and have Si-O-Si segments as crosslinking sites. Preferred vinylsilane monomers are those of the formula (I)

wherein

R represents hydrogen or methyl,

R is straight-chain or branched C -C ₂ alkyl, where the carbon chain can be interrupted by -O-, -NH-, -COO-, or -NH-COO-,

R 3 represents straight-chain or branched C ₁ -C ₆ -alkyl or phenyl,

X for a hydrolyzable radical from the group halogen, alkoxy or

Carboxylate stands,

n takes the value zero or one,

a takes the value zero, one or two and

b is 3 minus a.

Preferred examples of vinylsilane monomers of the formula (I) are vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyl-triethoxysilane, γ-methacryloxypropyl-methyl-dimethoxysilanoxysilane, Acryl-oxy-propyl-trimethoxysilane, γ-acryloxypropyl-triethoxysilane, γ-acryloxypropyl-methyl-dimethoxysilane and γ-acryloxypropyl-methyl-diethoxysilane. The production of the particularly preferred spherical, largely monodisperse vinyl polymers crosslinked via Si-O-Si groups is described in EP-A-417 539 and US-A-5 646 210.

The proportion of the spherical, largely monodisperse vinyl polymer in the non-aqueous polymer suspension according to the invention is important for the increase in viscosity under shear and for the critical shear rate.

The non-aqueous polymer suspensions according to the invention with a strongly dilatant flow behavior, based on the polymer suspension, preferably contain 25 to 85% by weight of spherical, largely monodisperse vinyl polymer, particularly preferably 30 to 80% by weight, very particularly preferably 35 to 75% by weight.

Component (b)

Preferred carrier liquids are polyhydroxy compounds, such as glycol, polyethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol with 5 to 25 ethylene oxide units and glycerol, formamide, dimethylformamide, dimethyl acetamide and N-methylpyrrolidone. Further preferred carrier liquids are aliphatic, cycloaliphatic and aromatic hydrocarbons, silicone oils, such as, for example, polysiloxanes, which may contain dimethyl, alkylmethyl, dialkyl, methylphenyl, diphenyl, monomethyl or fluoroalkyl groups. Other preferred carrier liquids are mineral oils, liquid distillation products obtained from mineral raw materials in the sense of the invention, which can be naphthenic as well as paraffinic.

Particularly preferred carrier liquids are polyols such as glycols and oligo- and polyglycols, silicone and mineral oils.

Mixtures of different carrier liquids can also be used. The non-aqueous polymer suspensions according to the invention with a strongly dilatant flow behavior preferably contain 5 to 74.9% by weight of carrier liquid, particularly preferably 12.5 to 69.75% by weight, very particularly preferably 20 to 64% by weight, based on the polymer suspension .-%.

Component (c)

As component (c), the polymer suspensions according to the invention preferably contain additives with a molecular weight greater than or equal to 100 to 1,000,000, particularly preferably 100 to 500,000, very particularly preferably 100 to 50,000.

Polymeric compounds which are mentioned, for example, in the directory “Water-Soluble Synthetic Polymers: Properties and Behavior” (Volume I + II by Philip Molyneux, CRC Press, Florida 1983/84) can be used as additives.

Also suitable as additives are surface-active compounds which are cationic, anionic, amophoteric and / or non-ionic in nature and, for example, in “Surfactants Europe, A. Directory of Surface Acitive Agents available in Europe (Edited by Gordon L. Hollis, Royal Society of Chemistry , Cambridge (1995) are used.

Polymeric additives of component (c) are, for example, water-soluble or water-emulsifiable compounds, such as homopolymers and copolymers, graft and graft copolymers and statistical block copolymers.

Particularly preferred polymeric additives of component (c) are, for example, AB, BAB and ABC block copolymers. In the AB or BAB block copolymers, the A segment is a hydrophobic homopolymer or copolymer which ensures a connection to component (b) and the B segment is a hydrophilic one

Homopolymer or copolymer or a salt thereof which is used to disperse the Component (a) ensures in the medium. Such polymeric additives and their synthesis are known, for example, from EP-A-518 225 and EP-A-556 649.

Further examples of preferred polymeric additives of component (c) are polyethylene oxides, polypropylene oxides, polyoxymethylenes, polytrimethylene oxides, polyvinyl methyl ether, polyethyleneimines, polyacrylic acids, polyarylamides, polymethacrylic acids, polymethacrylamides, poly-N, N-dimethyl-acrylamides, poly-N isopropyl acrylamides, poly-N-acrylglycinamides, poly-N-methacrylglycinamides, polyvinyl alcohols, polyvinyl acetates, copolymers of polyvinyl alcohols and polyvinyl acetates, polyvinyl pyrrolidone, polyvinyl oxazolidones, polyvinyl methyl oxazolidones.

Natural polymeric additives of component (c) such as cellulose, starch, gelatin or their derivatives and polyamino acids are also suitable.

Preferred anionic additives of component (c) are in particular condensation products of aromatic sulfonic acids with formaldehyde, such as, for example, condensation products from formaldehyde and alkylnaphthalenesulfonic acids, condensation products from formaldehyde, naphthalenesulfonic acids and / or benzenesulfonic acids or condensation products from optionally substituted phenol with formaldehyde and sodium bisulfite.

Further preferred anionic additives are condensation products which can be obtained by reacting naphthols with alkanols, addition of alkylene oxide and at least partial conversion of the terminal hydroxyl groups into sulfo groups or half esters of maleic acid, phthalic acid or succinic acid.

Further examples of preferred anionic polymeric additives of component (c) are the salts of polyacrylic acids, polyethylene sulfonic acids, polystyrene sulfonic acid, polymethacrylic acids, polyphosphoric acids. Preferred examples of anionic, polymeric additives of component (c) are furthermore copolymers of acrylic monomers, which are given below by way of example by combining monomers which are synthesized to random, alternating or graft copolymers:

Acrylamide, acrylic acid; Acrylamide, acrylonitrile; Acrylic acid, N-acrylglycinamide; Acrylic acid, ethyl acrylate; Acrylic acid, methyl acrylate; Acrylic acid, methylene butrolactam; N-acrylglycinamide, N-isopropylacrylamide; Methacrylamide, methacrylic acid; Methacrylic acid, benzyl methacrylate; Methacrylic acid, diphenylmethyl methacrylate; Methacrylic acid, methyl methacrylate; Methacrylic acid, styrene;

Preferred examples of cationic, polymeric additives of component (c) are the salts of polyethyleneimines, polyvinylamines, poly (2-vinylpyridines), poly (4-vinylpyridines), poly (diallyldimethylammonium) chloride, poly (4-vinylbenzyltrimethylammonium) salts, poly (2-vinyl piperidine).

Lignin sulfonates, for example those obtained by the sulfite or Kraft process, are also preferred. They are preferably products which are partially hydrolyzed, oxidized, propoxylated, sulfonated, sulfomethylated or disulfonated and fractionated by known methods, e.g. after this

Molecular weight or by degree of sulfonation. Mixtures of sulfite and kraft lignin sulfonates can also be used. Lignin sulfonates with an average molecular weight of greater than 1000 to 100,000, an active lignin sulfonate content of at least 80% and preferably with a low content of polyvalent cations are particularly preferred. The degree of sulfonation can vary within wide limits.

Preferred nonionic additives of component (c) are, for example, alkoxylates, alkylolamides, esters, amine oxides and alkypolyglycosides. Reaction products of alkylene oxides with alkylatable compounds, such as, for example, fatty alcohols, fatty amines, fatty acids, phenols, alkyl phenols, arylalkylphenols, such as, for example, styrene-phenol condensates, carboxylic acid amides and resin acids.

Examples of preferred anionic additives of component (c) are: alkyl sulfates, ether sulfates, ether carboxylates, phosphate esters, sulfosucinates,

Sulfosuccinatamides, paraffin sulfonates, olefin sulfonates, sarcosinates, isothionates, taurates and lignin compounds.

Also preferred are additives of component (c) from the group of the sulfosuccinic acid esters and alkylbenzenesulfonates and sulfated, alkoxylated fatty acid alcohols or their salts. From the group of alkoxylated fatty acid alcohols, use is made in particular of those with 5 to 120, preferably 5 to 60, in particular 5 to 30 ethylene oxide, C ₆ -C ₂ fatty acid alcohols which are saturated or unsaturated, in particular stearyl alcohol. A stearyl alcohol alkoxylated with 8 to 10 ethylene oxide units is particularly preferred. The sulfated alkoxylated

Fatty acid alcohols are preferably present as a salt, in particular as an alkali or amine salt, preferably as a diethylamine salt.

If the non-aqueous polymer suspensions according to the invention with a strongly dilatant flow behavior contain an additive, this is, based on the polymer suspension, preferably 0.1 to 10% by weight, particularly preferably 0.25 to 7.5% by weight, very particularly preferably 1 to 5% by weight.

A preferred embodiment of the polymer suspensions according to the invention contains, based on the polymer suspension

a) 25 to 85 wt .-% spherical, largely monodisperse

vinyl polymer,

b) 5 to 74.9 wt .-% carrier liquid and c) 0.1 to 10 wt .-% additive.

A particularly preferred embodiment of the polymer suspensions according to the invention contains, based on the polymer suspension

a) 30 to 80% by weight, spherical, largely monodisperse vinyl polymer,

b) 12.5 to 69.75 wt .-% carrier liquid and

c) 0.25 to 7.5 wt .-% additive.

A very particularly preferred embodiment of the polymer suspension according to the invention contains, based on the polymer suspension

a) 35 to 75 wt .-% spherical, largely monodisperse vinyl polymer

b) 20 to 64 wt .-% carrier liquid and

c) 1 to 5 wt .-% additive.

To produce the polymer suspensions according to the invention, component (a) in powder form or as a water-moist press cake is preferably first mixed with component (b) and, if appropriate, component (c) and processed to a homogeneous suspension. This can be done, for example, using an agitator, dissolver and similar devices.

In a further preferred production form, component (a) is dispersed in water in powder form or as a water-moist presscake in the presence of an additive, component (b) is mixed in and the water is removed by distillation. If necessary, pH regulators such as hydrochloric acid, acetic acid or sodium hydroxide solution are added to adjust the pH.

Examples

example 1

Production of a spherical, largely monodisperse vinyl polymer crosslinked via Si-O-Si groups

16 g of poly (styrene-co-maleic acid sodium salt) and 32.8 g of nonylphenol polyglycol (with 6 ethylene oxide units) were dissolved in a mixture of 4260 g of methanol and 2050 g of deionized water in a reaction flask with a reflux condenser, stirrer and thermometer. 1520 g of methyl methacrylate were added to the solution. The mixture was heated to 65 ° C with stirring. 80 g of γ-methacryloxypropyltrimethoxysilane and 8.2 g of sodium peroxodisulfate, dissolved in 33 g of deionized water, and 1 g of citric acid were then added and the mixture was stirred at 65 ° C. for 24 h. The reaction mixture was then cooled to 25 ° C. A vinyl polymer with an average particle size of 1.5 μm and a D _v / D _z of 1.01 was obtained.

Example 2

56 g of polyvinylpyrrolidone, 8 g of methyltricaprylammonium chloride and 0.64 g of azodisisobutyronitrile were dissolved in a mixture of 1440 ml of methanol and 160 ml of hexane in a reaction flask with a reflux condenser, stirrer and thermometer. A mixture of 97.5 methyl methacrylate and 2.5 g of γ-methacryloxypropyltrimethoxysilane was added to the solution. The mixture was heated with stirring for 5 hours and then cooled to 25 ° C. 100 ml of 1N HC1 were then added dropwise. The mixture was stirred for a further hour at 25 ° C, then the

Polymer isolated by centrifugation, washed with methanol and water and redispersed in water with the addition of 1 g of polyvinylpyrrohdon to a 20% suspension. A vinyl polymer with an average particle size of 2.0 μm and a Dv / D _z of 1.01 was obtained.

Example 3:

Preparation of a polymer suspension according to the invention

50 g of a 20% polymer suspension prepared according to Example 2 and 11.2 g of triethylene glycol were weighed into a 100 mL round-bottomed flask. The volatile constituents of this mixture were completely removed within 5 hours by means of a rotary evaporator at a bath temperature of 80 ° C. while slowly lowering the internal pressure to a value of 10 ^"3 bar. The mixture was then passed over a period of one hour at a pressure of 10 ^" distilled bar.

To determine the solids content, approximately 4-5 g of the suspension were weighed into an evaporation dish and dried in a drying cabinet at a temperature of 210 ° C. within 20-24 hours to constant mass. The anhydrous suspension produced had a solids content of 47.2%.

The viscosity of the suspension produced in this way was determined using the Bohlin CS rheometer as a function of the shear rate in the shear range from 0.1 to 1000 s ^"1 (cone / plate measuring system, cone angle 4 °, diameter 40 mm, measuring gap 150 The following viscosities were measured:

Viscosity before the critical shear rate: 1, 3 Pa s

Critical shear rate: 0.6 s ^"1

Viscosity after the critical shear rate: 174 Pa s Example 4:

Preparation of a suspension according to the invention

50 g of one prepared according to Example 2 were placed in a 100 mL round bottom flask

20% polymer dispersion and 10.7 g of triethylene glycol weighed out.

The volatile constituents of this mixture were completely removed within 5 hours by means of a rotary evaporator at a bath temperature of 80 ° C. while slowly lowering the internal pressure to a value of 10 ^"3 bar. The mixture was then passed over a period of one hour at a pressure of 10 ^" distilled bar.

To determine the solids content, about 4-5 g of the dispersion were weighed into an evaporation dish and dried in a drying cabinet at a temperature of 210 ° C. within 20-24 hours to constant mass. The anhydrous suspension thus produced has a solids content of 48.4%.

The viscosity of the suspension produced in this way was determined using the Bohlin CS rheometer as a function of the shear rate in the shear range from 0.1 to 1000 s ^-1 (cone / plate measuring system, cone angle 4 °, diameter

40 mm, measuring gap 150μm). The following viscosities were measured:

Viscosity before the critical shear rate: 5 Pa s

Critical shear rate: 0.16 s ^"1 Viscosity after the critical shear rate: 174 Pa s

Claims

claims

1. Containing non-aqueous polymer suspensions

a) a spherical, largely monodisperse vinyl polymer,

b) a carrier liquid and optionally

c) an additive.

2. Non-aqueous polymer suspensions according to claim 1, characterized in that the spherical, largely monodisperse vinyl polymer has an average particle size of 0.8 to 10 microns.

3. Non-aqueous polymer suspensions according to one or more of the preceding claims 1 and 2, characterized in that they, based on the polymer suspension

a) 25 to 85 wt .-% of a spherical, largely monodisperse vinyl polymer

b) 5 to 74.9 wt .-% of a carrier liquid and optionally

c) contain 0.1 to 10% by weight of an additive.

4. Non-aqueous polymer suspensions according to one or more of the preceding claims 1 to 3, characterized in that the spherical, largely monodisperse vinyl polymer is a copolymer of vinyl monomers and vinylsilane monomers crosslinked via Si-O-Si groups. Non-aqueous polymer suspensions according to claim 4, characterized in that the spherical, largely monodisperse vinyl polymer from a copolymer crosslinked via Si-O-Si groups

a) 50 - 99 wt .-% polymerized vinyl monomers and

b) 1-50% by weight of polymerized vinylsilane monomers of the formula (I)

is what

R ^{1 represents} hydrogen or methyl,

R ^{2 is} straight-chain or branched C -Ci ₂ alkyl, where the carbon chain can be interrupted by -O-, -NH-, -COO-, or -NH-COO-,

R ^{3 represents} straight-chain or branched C ₁ -C ₆ -alkyl or phenyl,

X for a hydrogenatable radical from the group halogen, alkoxy or

Carboxylate stands,

n takes the value zero or one,

a takes the value zero, one or two and b is 3 minus a.

6. A process for the preparation of non-aqueous polymer suspensions according to one or more of the preceding claims 1 to 5, characterized in that the spherical, largely monodisperse vinyl polymer in powder form or as a water-moist presscake is mixed with the carrier liquid and optionally with an additive and added a homogeneous suspension is processed.

7. A process for the preparation of non-aqueous polymer suspensions according to one or more of the preceding claims 1 to 5, characterized in that the spherical, largely monodisperse vinyl polymer in powder form or as a water-moist presscake is dispersed in water in the presence of an additive, the carrier liquid being admixed and the water is removed by distillation.

8. Use of the non-aqueous polymer suspensions according to one or more of the preceding claims 1 to 5 for shock and vibration damping.

9. Use of the non-aqueous polymer suspensions according to one or more of the preceding claims 1 to 5 as damping elements in leisure equipment and leisure shoes.