KR20020081419A - Method for Agglomerating Finely Divided Polybutadiene Latices - Google Patents

Abstract

The present invention relates to a process for agglomeration of finely divided rubber latex by addition of an aqueous solution of a water-soluble amphiphilic copolymer consisting of at least one hydrophobic segment and at least one hydrophilic segment. In addition, the process of the invention is characterized in that the molar weight HB of the largest hydrophobic segment in the amphiphilic copolymer exceeds 500 g / mol and the molar weight HL of the largest hydrophilic segment exceeds 2000 g / mol.

Description

Method for Agglomerating Finely Divided Polybutadiene Latices

The present invention relates to a process for agglomeration of fine particulate rubber latex by addition of an amphipathic block copolymer. The term agglomeration herein refers to the coalescence of latex particles forming a spherical mass in which the primary particles are fused together in part or in whole.

Coarse rubber particles can be prepared by direct emulsion polymerization as described, for example, in DE-As 1,247,665 and 1,269,360. However, this direct polymerization process has the disadvantage of long polymerization times, which typically last several days, until the desired particle diameter is achieved with nearly complete conversion. To shorten the polymerization time as much as possible, high polymerization temperatures are often used. This is difficult to remove and leads to the formation of Diels-Alder adducts such as vinylcyclohexene which remain permanently in the latex particles.

As an alternative to direct polymerization, coarse rubber particles can be produced by agglomeration of fine particulate latex. The term fine particulate latex means a latex having an average particle diameter (DVN) of 40 to 250 nm. The finer the latex, the shorter the polymerization time. Aggregation can be initiated by physical and chemical methods. In this regard, it is very difficult to avoid the formation of undesired coagulum, i.e. very large aggregates (range of several micrometers to mm size), which cannot be separated from the dispersion and redispersible. Such coarse fractions also reduce gloss and adversely affect the mechanical and surface properties of plastic materials, such as ABS, made from latex.

A chemical method of enlarging rubber latex is described in DE-A 2,606,715, whereby acetic anhydride is added to rubber latex. The acetic acid released by hydrolysis neutralizes the carboxylate emulsifier, making the latex unstable until the rubber particles aggregate. However, this method can only be used for weakly acidic emulsifiers, for example salts of organic acids. Latex stabilized with highly active sulfonate or sulfate emulsifiers cannot be aggregated in this way. In addition, this method has the disadvantage of being unable to stir the latex during the flocculation phase due to the extreme sensitivity of the latex to shear forces and stabilizing the latex with an acid-stable emulsifier or alkali after flocculation. This creates a large amount of wastewater. In particular, the possibility of performing continuous aggregation is excluded. Continuous flocculation has the great advantage that it can be controlled and controlled in the event of disturbances of aggregation and / or deviation from the desired mean aggregate size.

According to the teaching of DE-A 2,645,082, aggregation is initiated by oxidized polyethylene oxide. Agglomerated latexes have a very wide particle size distribution, which is a disadvantage, for example, in the manufacture of ABS. In addition, the latex obtained by this method is only limitedly stable in further processing steps. If unoxidized polyethylene oxide (PEO) is used, ammonium salts must be added (US-A 3,288,741), which results in a relatively high waste water burden. In EP-A 330,865 branched polyethylene oxides are used before and / or during emulsion polymerization. Here too, a considerable amount of alkali or ammonium salt must be used as well. The use of PEO-containing emulsifiers is also described, for example, in DE-A 2,323,547 (= US-A 4,014,843) or US-A 4,680,321. The use of PEO-containing emulsifiers leads to a wide particle size distribution with a significant proportion of unaggregated fine particulate rubber particles and can only avoid the formation of coagulum by using auxiliary emulsifiers.

In DE-A 2,427,960, a second latex containing a carboxyl group or an amide group is used as the flocculant. Aggregated latex has a very wide molecular size distribution and contains a significant proportion of unaggregated fine particulate rubber particles. When latex stabilized with PEO-PS-PEO triblock copolymer is used as flocculant, a narrow particle size distribution is achieved with no coagulum formation in accordance with the teachings of EP-A 249,554. However, the production of latex used as flocculant is difficult. Both methods involve expensive second latex production, resulting in additional costs.

It is an object of the present invention to develop an environmentally friendly and inexpensive method which can rapidly agglomerate fine particulate rubber latex to form a uniformly coarse rubber latex while producing less coagulum on a large scale in an economically viable manner.

Surprisingly, this object is achieved by the use of an amphiphilic block copolymer having a minimum molecular weight specific for hydrophilic and hydrophobic blocks for flocculation.

Thus, the present invention includes at least one hydrophilic segment and at least one hydrophobic segment,

Characterized in that the molecular weight HB of the largest hydrophobic segment exceeds 500 g / mol and the molecular weight HL of the largest hydrophilic segment exceeds 2000 g / mol

Provided is a method for agglomeration of fine particulate rubber latex by addition of a water-soluble amphiphilic copolymer aqueous solution.

The term segment refers to the consistent, linear, branched or cyclic portion of the copolymer having equal hydrophobicity and / or hydrophilicity, depending on its structure.

The rubber latex to be aggregated comprises at least one monomer selected from the group consisting of butadiene, isoprene, alkyl acrylates, preferably C ₁ -C ₈ alkyl acrylates, propylene oxide, dimethylsiloxane, phenylmethylsiloxane; 30 wt% or less, preferably 20 wt% or less of other monomers such as, for example, (meth) acrylic acid ester, styrene, acrylonitrile, glycidyl (meth) acrylate, allyl vinyl ether; For example, it is manufactured by emulsion-polymerizing 10 weight% or less, preferably 5 weight% or less of bifunctional crosslinking monomers, such as divinylbenzene, ethylene glycol dimethacrylate, and ethylene glycol diacrylate. Preferably at most 30% by weight, preferably at most 15% by weight and for example divinylbenzene, ethylene glycol dimethacrylate and other monomers such as (meth) acrylic acid esters, isoprene, styrene, acrylonitrile and Particular preference is given to latexes of butadiene with 10 wt% or less, preferably 5 wt% or less, of bifunctional crosslinking monomers such as ethylene glycol diacrylate. The rubber is characterized in that the glass transition temperature is below -20 ° C, preferably below -40 ° C. The particle size of the rubber particles is less than 300 nm, preferably 40 to 250 nm, particularly preferably 80 to 200 nm. These values refer to the d ₅₀ -value of the integral mass distribution, which can be measured, for example, by ultracentrifugation.

As emulsifiers, alkyl sulfates, alkyl sulfonates, aralkyl sulfonates, saturated or unsaturated fatty acids (eg oleic acid, stearic acid), oligomers thereof (eg oleic acid dimer) and alkaline disproportionate or hydrogenated abietin Conventional anionic emulsifiers such as soaps of acids or talloleic acid are generally used. Preferably, emulsifiers containing carboxyl group (s) (e.g., C ₁₀ -C ₁₈ fatty acids or oligomers thereof, salts of disproportionated abienic acid, DE-A 36,39,904 and DE-A 39, 13,509 emulsifiers) are used, particularly preferably alkaline salts of saturated or unsaturated oligomers of unsaturated aliphatic carboxylic acids, most particularly preferably alkali metal salts of dimers or trimer fatty acids having 24 to 66 carbon atoms This is used. In addition, mixtures of the above emulsifiers may be used. The emulsifier content is 0.2 to 6% by weight, preferably 0.5 to 2.5% by weight relative to the rubber to be aggregated.

When alkali metal salts of dimers or trimer fatty acids having 24 to 66 carbon atoms are used at least 50% by weight relative to the total amount of the emulsifier, the flocculation with the amphiphilic compounds according to the invention is carried out in a coagulation-free manner or in particular a low coagulation Proceed to the rate of water generation. As emulsifiers for the production of latexes, alkali metal salts of dimers or trimer fatty acids or mixtures thereof can be used in amounts up to 50% by weight of other anionic emulsifiers, for example carboxylate emulsifiers.

In order to reduce the viscosity and to make the agglomeration sensitive in the preparation of the latex to be agglomerated, conventional salts such as, for example, sodium sulfate, potassium chloride, sodium pyrophosphate or alkali metal carbonates may be used in amounts of 0.01 to 1% by weight relative to the rubber to It may be used in an amount of 0.1 to 1% by weight.

The production of rubber is generally known. For example, polybutadiene polymerization is initiated with a pyrolytic radical donor such as, for example, potassium persulfate or a redox initiator system as is generally known to those skilled in the art. The polymerization temperature of the polybutadiene is generally in the range from 5 ° C to 85 ° C, preferably 40 ° C to 70 ° C.

Rubber latexes which can be aggregated generally have a solids content of 30 to 50% by weight, preferably 35 to 45% by weight. Particular preference is given to narrow particle size distributions of low salt and low emulsifier diene latexes prepared by seed addition using 0.5 to 2.5% by weight of emulsifier and 0.1 to 0.25% of salt relative to rubber. With the emulsifier-coagulant combination according to the invention, there is no problem in the production of graft latex and ABS.

Rubber latex aggregates by addition of an aqueous solution of an amphipathic block copolymer. Aqueous solutions of block copolymers based on ethylene oxide are preferably used. The block copolymers may differ in molecular structure, for example linear, branched, comb or star. Amphiphilicity is ensured when the block copolymer comprises at least one hydrophobic segment and at least one hydrophilic segment.

The monomers belonging to the hydrophobic segment are selected from all available hydrophobic monomers. Preferred examples include styrene, α-methylstyrene and their nuclear substituted derivatives; Olefins having 3 to 12 carbon atoms, preferably butadiene and / or isoprene; Alkyl acrylates, alkyl methacrylates, preferably C ₁ -C ₄ -alkyl acrylates, C ₁ -C ₄ -alkyl methacrylates; Propylene oxide; Dimethylsiloxane, phenylmethylsiloxane; Aliphatic hydrocarboxylic acids having preferably 3 to 8 carbon atoms in the alkyl radical; The aromatic or aliphatic dicarboxylic acid, preferably aliphatic dicarboxylic acid or terephthalic acid having 3 to 12 carbon atoms in the alkyl radical and the carbon atom number of the alkyl radical is preferably 2 to 36, particularly preferably 2 to 18 Esters with aliphatic diols, in particular ethylene glycol, butanediol; Urethanes formed from said diols with aromatic or aliphatic diisocyanates, preferably selected from toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate and / or methylenediphenylene diisocyanate; Or mixtures of these monomers may be mentioned. In addition, the hydrophobic segment may contain up to 20% by weight of other monomers, ie hydrophilic monomers.

Monomers that may be included in the hydrophilic segment are all available hydrophilic monomers. Ethylene oxide, acrylamide, alkaline (meth) acrylate, vinylpyrrolidone, N-, 2- and 4-vinylpyridine, ethyleneimine, alkaline 4-styrenesulfonate, vinyl alcohol, dimethylaminoethyl (meth) acrylate Hydroxyethyl (meth) acrylate may be mentioned as a preferred example. The hydrophilic segment may also contain up to 30% by weight of other monomers, ie hydrophobic monomers as described above. Especially preferably, the hydrophilic segment comprises 70 to 100% by weight of ethylene oxide units and 30 to 0% by weight of propylene oxide units.

Preferred are linear polystyrene-polyethylene oxide diblock copolymers, and polydimethylsiloxane based branched copolymers with ethylene oxide containing side chains.

The block copolymer to be aggregated according to the invention has a molecular weight HB of at least 500 g / mol, preferably at least 600 g / mol of the largest hydrophobic segment, and a molecular weight HL of at least 2000 g / mol, preferably of the largest hydrophilic segment. Is characterized in that 2200 g / mol or more. Water-soluble compounds are preferred. Compounds that do not reach this minimum have little or even no coagulation action.

The molecular weight of the hydrophobic segment can generally be up to 20,000 g / mol, preferably up to 10,000 g / mol. The molecular weight of the hydrophilic segment is generally 100,000 g / mol or less, preferably 50,000 g / mol or less, particularly preferably 20,000 g / mol or less.

In addition, the aggregation solution may contain a plurality of such block copolymers and mixtures with these and other non-aggregating amphiphilic compounds and / or anionic emulsifiers up to 70% by weight.

The concentration of the block copolymer in the aggregation solution should generally be 1 to 50% by weight, preferably 5 to 30% by weight.

The flocculating solution may optionally contain up to 50% by weight of a water miscible organic solvent, preferably methanol, ethanol, dioxane, tetrahydrofuran, pyridine, acetone, methyl ethyl ketone or acetonitrile. The satisfactory effect of the flocculant is achieved only if a homogeneous solution is used.

The flocculation solution can be used immediately after preparation. However, when the flocculation solution is aged for 3 days or more at a temperature of 20 ° C to 40 ° C, the flocculation is more reproducible and more uniform, and coagulation formation is still satisfactory, but coagulation formation is reduced. Best results are obtained when the flocculation solution is aged for 1 week with stirring at 40 ° C.

0.01 to 10% by weight, preferably 0.05 to 5% by weight, in particular 0.04 to 2% by weight, based on rubber, is used for the aggregation. Coagulation is carried out by adding a coagulation solution to the rubber latex. The addition is generally within a few seconds, preferably less than 60 seconds, with thorough mixing at a temperature of 5 to 70 ° C., preferably 10 to 60 ° C., especially 10 to 50 ° C., most particularly preferably 20 to 40 ° C. Is carried out. If the temperature is higher than 70 ℃, coagulation formation is often promoted. Aggregation can be carried out both batchwise and continuously.

After the agglomeration is finished, additional stabilizers such as, for example, anionic emulsifiers or antioxidants can be added to the coagulant-latex. In addition, the flocculant-latex may be post-treated thermally or mechanically, for example by heating or homogenizer.

In all examples, the percentage value is a weight percentage of the rubber that aggregates in latex and a weight percentage of the total solution in a homogeneous solution.

The particle size of the initial latex and agglomerated latex was determined by laser correlation spectroscopy (LCS) ("ALV-5000 Multiple Tau digital Correlator" spectrometer, ALV-Laser Vertiebsgesellschaft mbH, Langen, Germany), wavelength 633 nm, scattering angle 90 °). In addition, the particle size distribution of some latexes was determined by ultracentrifugation or specific turbidity measurement (Dr Lange Digital Photometer LP 1W, Doctor Bruno Lange Gembeh & Co. Cage (Dr). Bruno Lange GmbH & Co. KG, Dusseldorf, Germany), wavelength 535 nm).

For some of the agglomerated latex, homogeneity was determined by a Zeiss standard transmission light microscope in a dark field mode with a polar field attached camera MC 63 and a polaroid film Polarplan 57, magnification 400 × and At 1000 × and a magnification of 1000 ×, oil-impregnated oil was applied between the lens and the cover glass).

<Rubber latex>

Polybutadiene latex was prepared in a VA steel autoclave under nitrogen. Polybutyl acrylate latex was polymerized in a 2 L glass flask under nitrogen.

In all seed addition polymerizations, the seed latex was polybutadiene with an average particle size d ₅₀ of less than 40 nm and a narrow particle size distribution.

When redox initiators were used, deionized water that had been boiled thoroughly was used to prepare the solution.

<Production of Polybutadiene Latex by Seeding Addition Method: Latex 1>

42,220 g deionized water, seed latex (polybutadiene) with average particle size of 40 nm, solid content of 35.3% by weight, narrow particle size distribution, dimer acid "Pripol® 1008" (Unikema 804 g of a 7.5 wt% solution of potassium salt and 48.3 g of sodium sulfate (Unichema, Germany) were placed in a 120 L capacity VA steel autoclave under nitrogen. The autoclave was sealed, metered in while stirring 4710 g of 1,3-butadiene and 66 g of t-dodecylmercaptan and the vessel contents were heated to 50 ° C. When the temperature is constant, first a solution of 9.6 g of t-butyl hydroperoxide (80%) and 480 g of deionized water is added at once, followed immediately by an iron (II) complexonate solution prepared under nitrogen. (Consisted of 13.464 g of EDTA-disodium salt in 100 g of solution, 75.176 g of 1 M NaOH and 7.092 g of (NH ₄ ) ₂ [Fe (SO ₄ ) ₂ ] .6H ₂ O) 7.5 g, sodium hydroxymethanesulfinate A solution of 6.5 g (dihydrate) and 100 g of fully boiled deionized water was added in one portion. An exothermic reaction occurred. As soon as the internal temperature exceeded the maximum, the following stream metering started simultaneously.

A) 1560 g of 1,3-butadiene and 199.8 g t-dodecylmercaptan for 10 hours,

B) 31,710 g of butadiene for 20 hours,

C) a solution of 38.4 g t-butyl hydroperoxide (80%) and 2500 g deionized water for 25 hours,

D) 9418 g of a 7.5 wt% solution of potassium salt of dimeric acid prepol® 1008 for 25 hours,

E) A solution of 26 g of hydroxymethanesulfinate dihydrate and 2476 g of deionized water for 25 hours.

The polymerization was stopped when the pressure dropped to 1.5 bar. Thereafter, the latex was degassed and transferred to a plastic container. 104 l of an emulsifier (potassium salt of the hydrogenated dimer acid "Freepol® 1008" of oleic acid), 0.13% of sodium sulfate, average particle diameter d ₅₀ 142 nm and solids 39.8% by weight of polybutadiene latex were obtained. . The integral and differential weight distribution of the particle diameter of this latex is shown in FIG.

Latex 1-8 of Table I were prepared in a similar manner. All latexes were similarly narrow in particle size distribution as determined by ultracentrifugation.

<Production of Polybutadiene Latex by Batch Method: Latex 9>

12255.8 g of deionized water, 3678.9 g of a 10% by weight solution of potassium oleate, 162.6 g of potassium (1 N), 62.74 g of tetrasodium diphosphate, 21.02 g of potassium persulfate and 52.55 g of t-dodecylmercaptan under 40 L Placed into a capacity VA steel autoclave. The autoclave was sealed and metered in while stirring 10511.1 g of 1,3-butadiene, and the contents of the vessel were heated to 54 ° C. As soon as this temperature was reached, this time point was defined as reaction time zero. The following temperature profile was adopted.

Reaction time (hours) Temperature (℃)

2.554.5

4.555

1256

1361

1464

1571

1674

When the pressure dropped to 2 bars, the polymerization was stopped. Thereafter, the latex was degassed and transferred to a plastic container.

34 L of polybutadiene latex containing 3.50% of potassium oleate salt and 0.6% of sodium diphosphate, having an average particle diameter d ₅₀ of 64 nm, d _LKS = 95 nm, and a solid content of 41.4% by weight was obtained.

<Preparation of polybutyl acrylate latex by seed addition method: latex 10>

405.1 g deionized water, seed latex (polybutadiene latex with an average particle size of 40 nm, 35.3% by weight solids, narrow particle distribution), dimer acid "Freepol® 1013" (Unikema, Germany 77.7 g of a 10% by weight solution of potassium salt and 0.65 g of sodium sulfate were placed in a 4 L glass flask. 88.7 g of n-butyl acrylate were metered in while stirring and the reactor contents were heated to 80 ° C. When the temperature was constant, a solution of 0.73 g of potassium persulfate, 5.61 g of sodium hydroxide (IN) and 30.7 g of deionized water was added at one time. The following stream meterings were started simultaneously and metered in within 4 hours.

F) 114.8 g of a 10% by weight solution of the potassium salt of the dimeric acid "Pripol® 1008", 0.65 g of sodium sulfate, 2.17 g of potassium persulfate, 20 g of sodium hydroxide (1 N) and 778.2 g of deionized water,

G) 874.3 g n-butyl acrylate.

At the end of the metering procedure, the reactor contents were further stirred at 80 ° C. for 2 hours before cooling. The latex was transferred to a plastic container.

Polybutyl acrylate latex 2.5 containing 2% of an emulsifier (potassium salt of hydrogenated dimer acid "Freepol® 1008" of oleic acid) and 0.13% of sodium sulfate, with an average particle diameter of 144 nm and a solids content of 40.9% by weight. L was obtained.

Latexes 10-12 listed in Table II were prepared in a similar manner.

Amphiphilic Compounds as Coagulants

<Compound I>

LB 25: polyether starting from butyl diglycol and having 15.6% propylene oxide (PO) and 63.5% ethylene oxide (EO) intermediate blocks and end capped with 20.9% EO; Average molecular weight (weight average molecular weight): 2200 (by Bayer AG).

<Compound II>

Borchigen SN 95: reaction product of trimer toluene diisocyanate with LB 25 and dimethylaminoethanol in a molar ratio 2: 1, commercial product of Bayer AG.

<Compound III>

VP SE 1030: Linear block copolymers with polystyrene blocks with an average molecular weight of 1000 g / mol and polyethylene oxide blocks with an average molecular weight of 3000 g / mol (from Goldschmidt AG, Essen, Germany).

<Compound IV>

VP ME 1030: Linear block copolymers with polymethyl methacrylate blocks with an average molecular weight of 1000 g / mol and polyethylene oxide blocks with an average molecular weight of 3000 g / mol (Goldschmidt AG, Essen, Germany)

<Compound V>

VP BE 1030: Linear block copolymer with poly (n-butyl acrylate) block of average molecular weight 1000 g / mol and polyethylene oxide block of average molecular weight 3000 g / mol (Goldschmidt AG)

<Compound VI>

VP SE 1010: Linear block copolymer with polystyrene block of average molecular weight 1000 g / mol and polyethylene oxide block of average molecular weight 1000 g / mol (Goldschmidt AG)

<Compound VII>

Desmodur® N 3300 (trimerized hexamethylene diisocinate, functional: 3.8, Bayer AG) 30 g (NCO 0.15 mol) and Baysilon® OF-OH 502 6 14.7 g of% (dimethylpolysiloxane with alcoholic OH group, functional value = 2, OH 6%, manufactured by Bayer AG) was stirred at 80 ° C. for 3 hours. 224 g (0.1 moles of OH) LB 25 were added and stirred at the same temperature until there was no NCO in the batch (until there are no more NCO bands (2263 to 2275 cm ⁻¹ ) in the IR spectrum). The material obtained was easily dispersed in water.

<Compound VIII>

Desmodur® N 3300 30 g (N5 0.15 mole) and PE 170 HN (adipic acid and hexanediol, and polyesters of neopentyl glycol, average molecular weight = 1700, functionality = 2, made by Bayer AG) 42.5 g (0.05 mol) was stirred at 80 ° C. for 3 hours. Thereafter, 224 g (0.1 mol) of LB 25 were added and stirred at the same temperature until the NCO disappeared from the batch. The material obtained was easily dispersed in water.

<Compound IX>

30 g of Desmodur® N 3300 (0.15 mol of NCO) and 42.5 g of PE 170 HN (0.05 mol of OH) were stirred at 80 ° C for 3 hours. Thereafter, 35 g (0.1 mol) of Carbowax 350 (methoxypolyethylene glycol, average molecular weight = 350, Bayer AG) were added and further stirred at the same temperature until NCO disappeared from the batch. . The material obtained was easily dispersed in water.

<Compound X>

Sovermol DDI (dimethyl diisocyanate, Henkel KGaA, Dusseldorf, Germany, average molecular weight 190 g / mol, NCO = 13.8%) 30.4 g (NCO 0.10 mol), LB 25 224 g (OH 0.1 mole) and 0.05 g of dibutylphosphoric acid were mixed and stirred at 80 ° C. until NCO disappeared from the batch. The material obtained was water soluble.

Compound XI

P1557-BdEO: Linear block copolymers (Polymer Source, Inc., with poly (1,4-butadiene) blocks with an average molecular weight of 5000 g / mol and polyethylene oxide blocks with an average molecular weight of 6000 g / mol. H7P, Canada 1J7 Montreal Lajoy 771, Quebec).

<Compound XII>

P914-SANa: Linear block copolymer (polymer source, Inc. product) with polystyrene blocks having an average molecular weight of 4100 g / mol and poly (sodium acrylate) blocks having an average molecular weight of 3200 g / mol.

<Compound XIII>

P1037-S4VP: Linear block copolymers with a polystyrene block with an average molecular weight of 3300 g / mol and a poly (4-vinylpyridine) block with an average molecular weight of 4750 g / mol (polymer source, Inc. product). Water soluble only under 0.5 mL of 1 N HCl per 0.5 g of P1037-S4VP).

<Compound XIV>

P1358-StAMD :: Linear block copolymers with polystyrene blocks having an average molecular weight of 16400 g / mol and polyamide blocks with an average molecular weight of 4000 g / mol (polymer source, Inc. products)

<Agglomeration of Rubber Latex>

<Example of Batch Aggregation: Example 1>

100 ml of latex 1 was placed in a 250 ml beaker. 3 ml of an 8% solution of compound II was added to the latex with stirring at one time. Aggregation occurred within a few seconds. After further stirring for 10 minutes, the latex was filtered and transferred to a 100 ml PE bottle. No clot formation was observed.

Agglomerated latex with an average particle size of 488 nm (LCS), a solids content of 39.1 wt%, and a narrow particle size distribution was obtained, which remained unchanged after storage for one month at room temperature. The integral and differential weight distribution of the particle diameter of this latex measured by ultracentrifugation is shown in FIG.

As in Example 1, the latexes listed in row 2 of Table III were experimentally aggregated with the flocculant concentrations listed in row 8 of Table III and the flocculant concentrations listed in row 10. The properties of the aggregated latexes are listed in rows 12-14. A typical dark field microscope image of the aggregated latex of Example 2 was reproduced in FIG. 3.

<Example of Continuous Aggregation: Example 19>

In a static mixer (6 mm in diameter, 12 mm in length), 1 60 L of latex per hour and 12 L of 1% solution of Compound II were continuously mixed. The aggregated latex was collected in a collector equipped with a stirrer. No clot formation was observed.

Agglomerated latex with an average particle size of 320 nm and solids of 32.9% by weight was obtained.

<Description of Example>

From Table III (see Examples 1-8 and 37), the use of dimer soap (potassium salt of Freepol® 1008 and Freepol® 1013) in the primary latex, and After addition of the flocculant (block amphiphile) according to the invention, it can be confirmed that a coagulant-free flocculent latex is obtained, which generally has a desired average particle diameter of about 300 to 600 nm. Coagulants II, III, VII and VIII are particularly advantageous.

If the amphipathic coagulant is not according to the present invention (see Comparative Examples V.9 to V.12), no agglomeration of latex actually occurred. That is, the block compounds VI, IX, X and I have proven ineffective because they do not have the proper structure. Thus, the "aggregate" latex only had a slightly larger average diameter. When VI, IX, X and I were added, coagulum formation did not occur.

A coagulant effective for dimer soap primary latex (Compound II, for Borgenen SN 95) is given by potassium oleate salt (Example 13), resin soap dressinate (Example 14), potassium palmitate salt (Example 15), d. Very large amounts of coagulum when used in primary particle sizes of similar particle size produced in flocculation experiments with urine acid potassium salts (Examples 16 and 19) and tallow fatty acid potassium salt T11 (Example 17) (10 to 60%) was formed. Dimer soap did not produce this large amount of coagulum. In addition, the latexes of Examples 13 to 17 did not substantially change the particle size compared to the primary latex after the coagulum was removed by filtration or sieving.

If the emulsifier was not a dimer or trimer fatty acid, the flocculation conditions had to be adjusted more precisely to minimize coagulation formation. Coagulation formation could be particularly reduced in the following way.

Dilution of the flocculating solution (see Examples 18 and 19)

Increased aggregation temperature below 70 ° C. (e.g. less coagulum may form at 50 ° C. than 20 ° C., see Examples 20 and 21)

Appropriate control of the coagulant structure (e.g. less coagulum could be formed if the hydrophobic blocks of amphiphilic compounds were made on the basis of polysiloxanes, see examples 15 and 22)

Addition of an additional emulsifier to the starting latex before flocculation (see Examples 20, 23 and 24).

Use of mixtures of flocculants and emulsifiers (for example mixtures of 80% by weight of amphipathic copolymer and 20% by weight of potassium oleate salt, see examples 13 and 25)

PH change of the latex (see Examples 26 and 27)

Improved complete mixing of the latex with the flocculating solution (if the latex is not exposed to excessive shear forces, otherwise a large amount of coagulum will form)

Dilution of the starting latex and / or the addition of additional emulsifiers will result in the formation of smaller aggregated particles, in which case the salt concentration is slightly raised (eg, addition of 0.5% by weight of Na ₂ SO ₄ , example 26 and 28) It is possible to increase the particle size without forming a large amount of coagulum.

Not only can the polybutadiene latex be agglomerated with the method according to the invention, but also as shown in Examples 29 to 35 using poly (n-butyl acrylate) latex, rubber latex is also generally agglomerated according to the method of the invention. Suitable for.

Examples 32-35 also showed that amphiphilic copolymers with hydrophilic segments having a structure not based on ethylene oxide are likewise suitable for aggregation.

From examples 31 to 35, it can be seen that latexes prepared using sulfonate emulsifiers can be agglomerated by the process according to the invention. Thus, the process according to the invention is not limited to only carboxylate emulsifiers.

When a flocculant not according to the invention (e.g. VI), based on emulsifiers other than dimers or trimer soaps, was used for flocculation of more sensitive latex, the effect of increasing particle size remained unsatisfactory and slightly A coagulated product of was formed (Comparative Example V36, Resin Acid Emulsifier).

Claims (8)

One or more hydrophilic segments and one or more hydrophobic segments, Characterized in that the molecular weight HB of the largest hydrophobic segment exceeds 500 g / mol and the molecular weight HL of the largest hydrophilic segment exceeds 2000 g / mol Agglomeration method of fine particulate rubber latex by addition of aqueous aqueous amphiphilic copolymer solution. The hydrophilic segment of the block copolymer according to claim 1, wherein the hydrophilic segment of the block copolymer is ethylene oxide, acrylamide, alkaline (meth) acrylate, vinylpyrrolidone, N-, 2- and 4-vinylpyridine, ethyleneimine, alkaline 4-styrenesulfone Acid salts, vinyl alcohol, dimethylaminoethyl (meth) acrylate, hydroxyethyl (meth) acrylate, mixtures of these monomers, or mixtures of at least one hydrophilic monomer and up to 30% by weight of hydrophobic monomers. . The hydrophobic segment of the block copolymer according to claim 1 or 2, wherein the hydrophobic segment of the block copolymer is styrene, α-methylstyrene, their nuclear substituted derivatives, olefins having 3 to 12 carbon atoms, alkyl acrylates, alkyl methacrylates, and propylene oxide. At least one hydrophobic group selected from the group consisting of dimethylsiloxane, phenylmethylsiloxane, aliphatic hydroxycarboxylic acid, ester of aromatic or aliphatic dicarboxyl and aliphatic diol, and urethane of aromatic or aliphatic diisocyanate and aliphatic diol And a monomer. The method according to any one of claims 1 to 3, characterized in that alkali metal salts of dimers or trimer fatty acids or mixtures of up to 50% by weight of these and other anionic emulsifiers are used as emulsifiers for latex to be aggregated. Way. The process according to any of claims 1 to 4, characterized in that the alkaline salts of saturated or unsaturated dimers of unsaturated aliphatic carboxylic acids are used as emulsifiers for the latex to be aggregated. The method according to claim 1, wherein the aggregation is carried out in a continuous procedure. Use for the preparation of impact resistant thermoplastic processable molding compositions of coarse particulate rubber latex prepared according to claim 1. A method for producing coarse particulate rubber latex, which is prepared by producing fine particulate rubber latex and then coagulating by adding the amphipathic copolymer according to any one of claims 1 to 6.