EP1098932A1

EP1098932A1 - Latex compositions for antistatic coatings and a process for preparation thereof

Info

Publication number: EP1098932A1
Application number: EP00925310A
Authority: EP
Inventors: Oleg Nikolaevich Primachenko; Klavdia Aleksandra Gagarina; Valery Pavlyuchenko; Sergey Stepanovich Ivanchev; Olga Sorochinskaya; Mikael Skrifvars; Toivo Kärnä; Hanna Laamanen; Jukka Koskinen
Original assignee: Neste Chemicals Oy
Current assignee: Neste Chemicals Oy
Priority date: 1999-05-07
Filing date: 2000-04-28
Publication date: 2001-05-16
Also published as: AU4406700A; FI991050L; WO2000068310A1; FI991050A7; FI991050A0

Abstract

The invention relates to antistatic compositions of cationic latexes of copolymers of vinyl aromatic compounds, alkyl esters of (meth)acrylic acid and amine containing monomers wherein said compositions contain hollow particle latexes as polymeric filler. Fillers are prepared by using anionic surfactants and recharged with other surfactants in order to eliminate the latex coagulation in the preparation of the antistatic compositions.

Description

LATEX COMPOSITIONS FOR ANTISTATIC COATINGS AND A PROCESS FOR PREPARATION THEREOF

5

FIELD OF THE INVENTION

The present invention relates to water based polymer compositions useful for antistatic coating preparation. More specifically, it relates to water based polymer compositions l o comprising conductive polymer binder and non-conductive filler. Such compositions are useful as antistatic and dissipating materials and coatings for paper industry, construction, electronics, trimming and photographic materials.

BACKGROUND OF THE INVENTION

15

Antistatic polymeric coatings are a type of electroconductive coatings with specific surface resistance p_s = 10⁹ - 10¹⁵ ohm.

Waterborne coatings provide the most perspective approach to the formation of antistatic polymeric coatings from ecological and economical respects. A particularly promising

20 direction is concerned with the coatings obtained on the basis of polymeric latexes since in contrast to solutions latex systems afford the preparation of compositions with low viscosity at high polymer content. Low viscosity of these compositions extends the range of coating preparation methods, i.e. direct latex casting, dipping, spraying etc. In addition, the application of latex compositions allows water-resistant polymeric coatings without

25 their preliminary curing at high temperatures which is impossible to achieve using solution systems.

Finnish patent application FI 960936 (Russian Patent Application No. 98101565/04) discloses the method for the preparation of copolymers for antistatic coatings on the basis of aqueous film-forming latexes of amine-containing copolymers. The application of such

30 latexes affords antistatic coatings with p_s = 10⁷ - 10" ohm. However the increased content of amine-containing units providing the antistatic properties results in the decrease in the coating hardness and the coatings prepared become tacky. The use of filled latex compositions makes it possible to eliminate these drawbacks and improve other coating properties.

Chinese patent CN 1 100 449 discloses the application of aqueous antistatic colouring 5 compositions on the basis of poly(meth)acrylic salts filled with titanium dioxide for antistatic flame-retardant ceiling coatings. In order to prevent titanium dioxide sedimentation silica is added to the dispersion providing the formation of thixotropic structure of the composition. Thixotropic compositions have not so wide application sphere as a result of limited range of coating deposition techniques. The use of mineral fillers l o leads to the deterioration of the antistatic properties of the coatings and increase in their density (see comparative example).

US 5 268 407 discloses antistatic compositions on the basis of aqueous solutions of conductive polymers based on (meth)acrylic derivatives of quarternary ammonium salts with vinyl or acrylic comonomers, the said compositions being filled with water-soluble

15 salts of multivalent metals and used for making antistatic coatings (p_s = 5 * 10⁷ ohm) for electrophotographic and electrostatic paper. The application of up to 10 wt-% multivalent metal salts that are usually coloured in the composition complicates the preparation of transparent and light coloured coatings. Other disadvantages of water solution based compositions are well known as described

20 above.

More promising way is concerned with the application of latex compositions comprising polymeric fillers.

US 5 500 457 discloses latex compositions on the basis of core-shell copolymers filled with polymer particles for making colour-sensitive antistatic coatings for

25 electrophotographic or xerographic applications. This method affords the coatings with p_s = 2*10" ohm at the deposition from the prepared dilute (solids 5.7 wt-%) latexes. The use of low-molecular antistatics in this invention does not provide a long-term antistatic effect of the coating. This drawback is eliminated by using antistatic polymer latexes simultaneously acting as a

30 binder in the composition. Such antistatic polymer latexes usually comprise ionizable functional groups. Depending on the type of ionizing groups the latexes are stabilized with either anionic or cationic surfactants, in some cases in combination with non-ionic ones, to form anionic or cationic latexes correspondingly. Carboxy- or sulfur-containing are commonly used for the preparation of anionic latexes. In case of cationic latexes amino- monomers or monomers containing ammonia groups are most often applied as ionizing

monomers. Antistatics containing amino units particularly in the form of ammonia salts prepared by the neutralization of amines are known to be more efficient in comparison with those containing anionic units. Therefore the application of amine-containing polymer antistatic latexes is mostly preferable. The filler polymer particles incorporated into a cationic latex should be either electrically neutral or their particles should be positively charged. Otherwise the formation of aggregative stable latex composition is impossible. The most common filler form is a latex since in this case the composition preparation process is mostly convenient and economically efficient. In this case there is no necessity in using special equipment to prepare filler aqueous dispersions and adding an additional amount of surfactant for their stabilization.

The appropriate latex fillers are aqueous dispersions of rigid polymers such as polystyrene, most preferentially latexes with hard hollow particles. In this case the filler provides the decrease in the coating density. In addition, hollow particles can perform a function of a white pigment. US 4 427 836, US 5 157 084, WO 95/11265 and many other patents disclose hollow polymer particle latexes. However particles of these anionic latexes are negatively charged and therefore cannot be incorporated into the cationic latexes of polymeric antistatics without coagulation. US 4 469 825 discloses a method for the preparation of latexes with cationic hollow polymeric particles consisting of the core comprising crosslinked copolymer of methyl methacrylate with amino-monomer and the shell comprising poly(isobuthyl methacrylate). This method has the following disadvantages:

1. A large coagulum amount (higher than 50 wt-%) is formed at the synthesis.

2. Too high cationic surfactant concentrations (about 10 wt-%) are used at the stage of latex particle core formation.

3. The solids of the final latex is low (about 8 wt-%).

These cationic latexes with hollow particle fillers are useful for the preparation of latex compositions for antistatic coatings on the basis of electroconductive latexes with positively charged particles. However such compositions have a significant disadvantage since low solids in the polymeric latex filler (no more than 8 wt-%) make it impossible to

5 attain high solids (40-50 wt-%) in the composition.

In general, all components for latex antistatic compositions of the state of art do not allow the preparation of aggregative stable antistatic latex compositions with high solids comprising cationic latexes of amine-containing polymer antistatic and hollow polymer l o particles as a filler.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a latex composition suitable for

15 antistatic coatings, comprising cationic copolymer latex of vinyl aromatic monomer/(meth)acrylic ester/amine containing monomer from about 65% by weight to about 95% by weight, based on the total dry weight of the latex composition and styrene- acrylate hollow particle latex as a filler from about 5% by weight to about 35% by weight based on the total dry weight of the latex composition are used.

20 It is another object of the present invention to provide a simple process of the latex composition preparation, characterized in that before blending of the cationic latex and the hollow particle latex with negative ς-potential from -10 to -55 mV, particle size from 200 to 1000 nm, and solids from 30% by weight to 40% by weight said hollow particle latex is recharged with from 4% by weight to 9% by weight based on the total weight of dry

25 hollow polymer of cationic surfactant selected from the group of quartemary ammonium salts, ς-potential of the recharged hollow particle latex becoming positive one from +15 mV to +55 mV.

In another aspect, the invention comprises antistatic latex coatings prepared on the basis of said latex compositions at the temperature higher compared to the minimum film formation

30 temperature of said latex compositions.

DETAILED DESCRIPTION OF THE INVENTION Latex compositions of the invention comprise cationic latex of amine-containing polymer and hollow particle latex, wherein the weight ratio of these latexes based on dry weight ranges from about 95/5 to about 65/35, preferably from about 95/5 to 80/20. Copolymers of vinyl-aromatic compounds, alkylic esters of (meth)acrylic acid and amine-

containing monomers are used as cationic polymer latexes.

At the synthesis of such copolymers styrene and its alkyl- or halogen-substituted derivatives are used as vinyl-aromatic compounds. Methyl-, ethyl-, n-butyl-, i-butyl-, octyl- and 2-ethyl hexyl acrylates as well as methyl-, ethyl- and n-butyl methacrylates are used as alkylic esters of (meth)acrylic ester. Aminoalkyl esters of (meth)acrylic acid and vinyl pyridine derivatives are used as amine- containing monomers. Dimethyl, diethylaminoethyl acrylates; methyl-n-butyl, ethyln-butylaminoethyl acrylates; dimethylaminoethyl methacrylate; dimethylaminopropyl methacrylate; dimethyl, diethyl, dipropylaminoethyl methacrylates; methylaminoethyl methacrylate are used as amino-alkyl esters, 2-methyl-5-vinyl pyridine, 5-ethyl-2-vinyl pyridine, l,2-dimethyl-5-vinylpyridinium methylsulfate are used as vinyl pyridine derivatives. Amine-containing copolymer latexes can have either uniform morphology of latex particles comprising only amine-containing copolymer or core-shell latex particle morphology with amine containing copolymer encapsulated in the latex particle shell. Amine-containing polymer latexes prepared using cationic surfactants consist of positively charged particles (z-potential from +15 to +50 mV, preferably from +20 to +40 mV). The amine-containing latex copolymer particle size varies within the range from 50 to 2000 nm, preferably from 100 to 300 nm).

Cationic amine-containing polymer latexes have minimum film formation temperature from 30 to 70°C, preferably from 40 to 60°C.

In order to prepare highly concentrated latex compositions latexes of amine-containing copolymers with solids 40-55 wt-% are used. The recipes of amine-containing latex copolymers forming antistatic latex coatings with _ps = 10⁷ - 10⁹ ohm are selected for the latex composition preparation.

Styrene-acrylate copolymer based hollow polymer particle latexes are used as copolymer fillers for latex compositions, said latexes have negative particle charge (ς-potential from - 10 to -55 mV, preferably from -30 to -45 mV).

Commercially available hollow particle latexes such as Ropaque-543 or Ropaque OP842M can be used. Besides a hollow polymer latex can be prepared by the process comprising (A) emulsion polymerization of a core from a core monomer system comprising at least one unsaturated monomer containing acid functionality, (meth)acrylic ester and optionally

styrene optionally in the presence of seed latex; (B) encapsulating said core with a hard shell by emulsion polymerizing a shell monomer system containing at least styrene and/or (meth)acrylic ester in the presence of said core; (C) addition of the shell monomers, a radical inhibitor, a nonionic surfactant and volatile base into the resultant core-shell polymer particles and swelling of said core-shell particles at elevated temperature followed by (D) polymerization of shell monomers added at stage (C). Core monomer system and shell monomer system can contain a crosslinking monomer such as divinyl benzene, ethylene glycol methacrylate, allyl methacrylate. Emulsion polymerization is carried out in the presence of water-soluble free radical initiators such as sodium, potassium or ammonium persulfate and anionic surfactants such as sodium dodecyl benzene sulfonate at a temperature from 70°C to 95°C. Semicontinuous polymerizations are carried out at continuous feeding of the components. The hollow particle size in such latexes should be within the range from 200 to 1000 nm, preferably from 400 to 950 nm.

In order to prepare highly concentrated latex compositions hollow polymer particle latexes with solids 30-40 wt-% are used. Since the presently known highly concentrated hollow polymer particle latexes are anionic ones obtaining of compositions on the basis of cationic latexes in order to eliminate the latex coagulation at the composition preparation requires recharging of hollow polymer particle latexes.

Recharging of anionic latexes is performed using aqueous solutions of cationic surfactants selected from the group of quartemary ammonium salts. Recharging of negatively charged hollow polymer latex particles with ς-potential from -10 with -55 mV is carried out until their ς-potential changes from negative to posiitive values and becomes equal to from +15 to +55 mV.

Higher alkyltrimethylammonium halides such as decyl, undecyl, dodecyl, hexadecyl, octadecyl, docozyltrimethylammonium chlorides and bromides; higher C_2.4- alkyltrimethyl()ammoniumhalides; tetradecyl, hexadecyl, octadecyltriethyl(propyl,butyl)ammonium chlorides and bromides; C_10.,₈- alkylbenzyldimethylammonium chloride are used as cationic surfactants. At recharging cationic surfactant is fed as 10-50%wt., preferably 25-50% wt. aqueous solution into a latex with negatively charged particles with the feeding rate higher than 7.0* 10^"3 mol(surfactant)/100 g (dry hollow polymer)*s.

Decrease of the cationic surfactant feeding rate leads to the latex coagulation. Latex compositions are prepared by simple mixing cationic polymer latexes with recharged hollow polymer particle latexes at room temperature without using any additional surfactant at mixing.

The application of highly concentrated cationic polymer latexes and hollow

polymer particle latexes affords latex compositions with solids from 35 to 50 wt-%. The latex composition preparation proceeds without the latex coagulation. Latexes and latex compositions obtained according to the claimed method are characterized and analyzed by the following techniques. ς-potential was estimated by macroelectrophoresis technique at Barton installation using latexes with the concentration 7% and 0.025 N KC1 solution as a side liquid. The ς- potential was calculated using the Helmholtz-Smolukhovsky equation 4p_ηU₀

D where h is viscosity and D is dielectric permeability of the dispersion medium (water) and they are equal to 0.1 cP and 81, correspondingly,

U₀ is electrophoretic mobility of the particles determined according to the equation U * l U₀ = '

E where U is latex side liquid boundary shift rate, E is potential difference equal to 100 V in our experiments, 1 is distance between the electrodes - 24 cm. For recharging from 1.0% by weight to 3.0% by weight based on the total weight of dry hollow polymer of hydrochloric acid may or may not be added into the aqueous solution of cationic surfactant.

Examples

The following examples are provided for illustrative purposes only, and do not limit the

scope of the invention, which is reflected only by the claims.

Example 1

Preparation of amine-containing copolymer cationic latex

Example la

A 0.5 L round-bottomed flask is equipped with a paddle stirrer, thermometer, nitrogen inlet

and reflux condenser. 100 g deionized water containing 4.0 g dissolved cationic surfactant trimethyldodecylammonium chloride (TMDDAC) is loaded into the reactor, the reactor content is treated with nitrogen flow, the reaction mixture is heated up to 70°C followed by the addition of 25 g monomer mixture containing styrene (ST), butyl acrylate (B A) and dimethacrylic ester of ethylene glycol (DMEG) with the weight ratio 47.3:52.3:0.4 at stirring; in 5 min 0.162 g azo-initiator 2,2'-azobis(2-aminopropan)dihydrochloride; then copolymerization is performed within 1 hour to obtain the seed latex. 5 ml aqueous solution of HCl (10%) is fed into the prepared seed latex at stirring within 10 min; then 0.333 g of the above azo-initiator is charged followed by feeding 75 g of monomer mixture containing ST, BA and dimethylaminoethyl methacrylate (DMAEMA) (weight ratio 38.0:42.0:20.0) with the rate 18.75 g/hour. At the latex particle shell formation stage the additional amount of azo-initiator is charged: 0.162 g in 2 hours after the start of monomer mixture feeding and 0.162 g in 4 hours after the start of monomer mixture feeding. When the feeding is completed the latex is heated at 70°C within 0.5 hour and at 80°C within 1 hour. The resulting core-shell latex has solids 50.8% wt., pH 4.5, latex particle size 260 nm, viscosity 37.2 cP, ς-potential +15 mV.

Example lb

5

2 g TMDDAC is dissolved in 100 g deionized water; then 2.5 mg aqueous solution of HCl (10%), 0.2 g azo-initiator are charged and 80.0 g monomer mixture containing ST, BA and diethyl -aminoethyl methacrylate (weight ratio 45.0:40.0:15.0) is fed with the rate 16.0 g/hour. The process is performed at 70°C. The additional 0.2, 0.2 and 0.1 g azo- 10 initiator is

charged correspondingly in 2, 4 and 5 hours after the start of monomer mixture feeding. Then the latex is heated at 80°C within 1 hour. The resulting latex with uniform particle morphology, solids 15 44.8%> wt, pH 4.0, latex particle size 150 nm, viscosity 30.0 cP, ς-potential +36 mV.

Example lc

The latex is prepared according to the process of example la but the weight ratio

20

ST:B A:DMAEMA=40.45 :40.45 : 19.1.

The resulting core-shell latex has solids 41.8% wt., pH 5.5, latex particle size 200 nm, viscosity 76.9 cP, ς-potential +21 mV.

Other latex recipes with the particle ς-potential from +15 to 50 mV can be also used as 25 cationic latexes of amine-containing copolymers.

Example 2.

Preparation of hollow particle latex.

30 Stage A. Core polymer preparation.

The process is carried out in 250 ml flask equipped with stirrer, reflux condenser, inlet for nitrogen and necks for feeding components. The feed is fulfilled with syringe pumps. Step 1. Seed latex preparation. Recipe monomer mixture 1 : Methyl methacrylate (MMA) 0.544 g n-butyl acrylate (BA) 0.650 g

Methacrylic acid (MAA) 0.056 g

Sodium dodecylbenzene sulfonate (SDBS) 3.00 g (0.21% aqueous solution) Potassium persulfate (PP) 6.12 g (1.96%) aqueous solution)

Distilled water 45.0 g

This step is carried out as a batch process. 45.0 g of distilled water is charged into the flaskand heated up to 82°C with stirring and nitrogen flow. Then SDBS solution is charged. In 5 min PP solution and monomer mixture 1 are added. The process period (after the monomer mixture charge) is 1 hour.

Seed particle size is 90 nm.

Step 2. Final core polymer preparation.

Recipe

Seed latex prepared at step 1.

Monomer mixture 2

MMA 22.93 g

Styrene (ST) 1.65 g

Methacrylic acid 8.25 g

Ethylene glycol methacrylate 0.165 g SDBS (20.8% aqueous solution) 0.89 g aqueous phase:

PP O.l lό g

Distilled water 96.00 g Step 2 starts straight away after completing step 1. The monomer mixture 2 and aqueous phase are simultaneously fed into the seed latex within 3 hours. Then the process is continued for another 20 min followed by cooling, discharging and filtering of the latex prepared.

Solids of the latex is 17.8% wt. Average particle size is 200 nm.

Stage B. Hard shell preparation.

The process is carried out in 500 ml flask equipped with stirrer, reflux condenser, inlet for nitrogen and necks for feeding components.

Recipe

Latex of core polymer 5.73 g ST 93.89 g

PP (1.47% aqueous solution) 33.90 g

Distilled water 70.6 g

Aqueous phase for feeding: PP 0.73 g

SDBS 0.497 g

Distilled water 42.29 g

Latex of core-shell polymer and distilled water are charged into the flask. The flask content is heated in the nitrogen flow up to 85°C, then aqueous solution of PP is added followed by feeding styrene and aqueous phase. Feeding is carried out for 130 min.

Stage C. Swelling of the particles. Recipe Latex recharged at stage B

Ammonia aqueous solution (cone. 10.4% wt.) 4J6 g

ST 9.39 g

2,2,6,6-tetramethyl-4-oxo-pyperidine-oxyl-l (TEMPO) 0.177 g Nonionic surfactant Disponil APE 257 aqueous solution (cone. 18.1% wt.) 5.32 g

All the components (nonionic surfactant, ammonia and ST with dissolved TEMPO) are sequentially charged into the latex dropwαse within 4-5 min. Then the reflux condenser is closed and within the next 10-15 min the temperature is increased up to 95-96°C and the reaction mixture is maintained for 60 min. Then the temperature is reduced to 85°C within 10-15 min.

Stage D. Polymerization of styrene added at stage C.

0.70 g of ammonia persulfate dissolved in 12.0 g of water is charged and the reaction 0.71 mixture is kept at 85°C for 40 min. Then the latex is cooled and filtered. Solids of the latex is 31.2% wt. Particle size is 840 nm.

Example 3.

Recharging of anionic hollow particle latex.

The latex Ropaque HP-543 of Rohm & Haas Co. Or hollow particle latex prepared according to example 2 are used. The performances of the hollow particle latexes are as follows:

Hollow latex Solids, % Particle size, nm Viscosity, cP ς^' -potential, mV

Ropaque HP-543 30.6 500 13 -42

Latex of example 2 31.2 840 15 -45

Recharging of the latex is performed as follows. Aqueous solution of cationic surfactant is fed into 100 g of the hollow particle latex. If hydrochloric acid is used it is incorporated preliminarily into the aqueous solution of cationic surfactant. The recharging recipes, feeding rates of cationic surfactant into the hollow latex and properties of recharged latexes are presented in Table 1.

Table 1

Recharging Recipes and Properties of Recharged Latexes

Example Cationic surfactant Hollow Surfactant amount Recharging rate Performances of latex compositions No latex mol (surfactant)/ mol (surfactant)/

Type Cone, 100 g (hollow polymer) 100 g (hollow Coagulum Solids, Brookfield viscosity, ς-potential, % wt. polymer polymer) s % wt. % wt. cP (#2, 50 rpm, 20°C mV

3a TMDDAC 36.5 Ropaque- 1.52 10^" 7.6 10^"3 no 30.9 317.0 +31.0 543

3b TMDDAC 36.5 ditto 3.41 10^"2 1.7 lO^"2 no 30.8 69.9 +27.0

3c TMDDAB* 50.0 ditto 1.62 10^"2 8.1 lO^"3 no 30.8 250.0 +30.5

3d TMDDAB 50.0 ditto 2.27 10^"2 1.1 lO² no 30.8 65.0 +27.0

3e TMDDAC 36.5 ditto 1.52 lO^"2 5.1 10^"4 100

3f TMDDAC 10.0 ditto 1.52 lO^'2 5.1 10^"4 100

3g TMDDAC 36.5 ditto 1.52 10^"2 3.0 10^"3 27 22.4 180.0 +29.0

^~3h TMDDAC 36! Example 2 3.41 10^"2 1.7 lO^" no 32.0 +55.0

3i** TMDDAC 36.5 Example 2 2.65 10^'2 1.3 lO^'2 no 29.2 +45.0

* - TMDDAB - trimethyldodecylammonium bromide ** - 3.2 * 10^"2 mol HCl is added into the aqueous solution of cationic surfactant

The data presented in Table 1 show that the cationic surfactant feeding rate into the hollow latex should be 7.0* 10^~3 mol(surfactant)/100 g(dry hollow polymer)*s or higher. In case the feeding rate is less than this value partial or complete coagulation takes place.

Example 4.

Preparation of latex composition.

The recharged hollow polymer particle latex prepared according to example 3 is added to 100 g of cationic amine containing polymer latex prepared according to Example 1 at stirring.

The composition preparation is performed within 5 min. No coagulum formation is observed at the composition preparation, the composition is stable during the preparation, application and storage. No stratification of the composition is observed. Properties of the latex compositions are presented in Table 2.

Table 2

Properties of Latex Compositions

Example Cationic latex Recharged hollow Polymer filler Performances of latex compositions No (example No) particle latex content in the composition. Solids, MF1 , Brookfield viscosity.

Example No Amount, % wt. (based % wt. °C cP (#2, 50 rpm, 20°C from Table 1 σ on solid polymer)

4a la 3a 88.5 35 41.5 41.8 180.0

4b la 3a 8.7 5 49.2 37.2 50.0

4c lb 3a 36.2 20 41.1 50.0 140.0

4d lc 3b 33.9 20 39.0 47.8 91.0

4e lc 3b 16.9 10 40.2 44.3 82.1

4f lc 3c 33.9 20 39.1 47.3 108.9

4g lb 3d 7.7 5 43.8 42.3 30.0

4h lc 3h 32.6 20 39.4 47.0 4i lc 3i 35.8 20 38.5 47.0

4j* lb TiO, 2.7 42.0 42.5 26.1

(comparative)

TiO_n dispersion in 1.0% aqueous solution of TMDDAC was used to prepare the stable composition

Example 5.

Preparation of antistatic coating.

Antistatic coating prepared on the basis of the latex composition prepared according to example 4 is deposited onto the surface of ABS-plastic discs with 100 mm diameter and 2 mm width. The period of drying is 30 min. The coating method, the drying temperature and antistatic coating properties are presented in Table 3.

Table 3

Properties of Antistatic Coatings

Example Composition Coating method Drying temperature, Coating Performances No (example No °C from Table 2) p_s, ohm Relative Tackiness Density,

(RH=65%) hardness g/cm³

la* - dipping 50 2.0 10⁸ 0.42 slight 1.16 lb* - dipping 70 8.6 10⁷ 0.49 no 1.14 lc* - dipping 50 2.5 10^s 0.39 slight 1.16

5a 4a dipping 70 4.0 10⁹ 0.58 no 0.87

5b 4b dipping 50 2.4 10^s 0.50 no 1 .12

5c 4a dipping 70 1.7 10⁸ 0.44 no 1.01

5d 4d dipping 70 2.2 10⁸ 0.46 no 0.99

5e 4e dipping 70 1.9 10^s 0.44 no 1.12

5f 4f direct latex 70 3.4 10⁷ 0.58 no - casting

5g 4g dipping 50 1.8 10^s 0.52 no 1.06

5h 4a dipping 20 coating was not formed

5i 4h direct latex casting 60 3.1 10⁷ 0.41 no 1.09

5j 4i direct latex casting 60 1.5 10⁷ 0.47 no 1.1 1

5k 4j direct latex 50 7.4 10⁹ 0.52 no 1.24

(comparative) casting performances of non- filled coatings

Claims

1. A latex composition comprising a cationic latex and a polymeric filler characterized in that the cationic latex of amine containing copolymer from about 65% by weight to about 95% by weight, based on the total dry weight of the latex composition and hollow particles as a polymeric filler from about 5% by weight to about 35% by weight based on the total dry weight of the latex composition are used.

2. The latex composition according to claim 1, characterized in that the amine containing copolymer is a copolymer of vinyl aromatic compound, (meth)acrylic ester, and amine containing monomer.

3. The latex composition according to claims 1 and 2, characterized in that particles of the cationic latex of the amine-containing copolymer have a core-shell morphology.

4. The latex composition according to claims 1-3, characterized in that the latex of amine containing copolymer has positive ς-potential from +15 to +50 mV, particles of from 50 to 2000 nm in size, and solids of from 40 to 55 %wt.

5. The latex composition according to claims 1-4, characterized in that the hollow particle latex, comprising particles of styrene-acrylate copolymer, has negative ς-potential from -10 mV to -55 mV, and solids in the range from 30 %wt. to 40 %wt.

6. The latex composition according to claims 1-5, characterized in that the hollow particle latex comprising particles of styrene-acrylate copolymer, is prepared by the process, comprising (A) emulsion polymerization of a core from a core monomer system containing at least one unsaturated monomer containing acid functionality, (meth)acrylic ester and optionally styrene optionally in the presence of seed latex; (B) encapsulating said core with a hard shell by emulsion polymerizing a shell monomer system containing at least styrene and/or (meth)acrylic ester in the presence of said core; (C) addition of the shell monomers, a radical inhibitor, a nonionic surfactant and volatile base into the resultant core-shell polymer particles and swelling of said core-shell particles at elevated temperature followed by (D) polymerization of . tell monomers added at stage (C).

7. The latex composition according to claim-, 1 6, characterized in that the solids of said latex compositions ranges from 35% wt. to 50 %wt. and minimum film formation temperature from 30 to 70°C.

8. A process for preparation of the latex compos ion according to claims 1-7, characterized in that before blending of the cationic latex of amine containing polymer and the hollow particle latex, having negative ς-potential, said hjllow particle latex is recharged with from 4%> by weight to 9% by weight based on the total weight of dry hollow polymer of cationic surfactant selected from quartemary ammonium salts, ς-potential of the recharged hollow particle latex becoming positive one from +15 to +55 mV.

9. A process for preparation of the latex composition according to claim 7, characterized in that the recharging of the hollow particle latex is carried out with from 4% by weight to 9% by weight based on the total weight of dry hollow polymer of cationic surfactant selected from quartemary ammonium salts and from 1.0% by weight to 3.0% by weight based on the total weight of dry hollow polymer of hydrochloric acid.

10. A process for preparation of the latex composition according to claim 8, characterized in that the cationic surfactant is injected into the hollow polymer latex at the rate of higher than 7.0* 10^"2 mol/s per 100 g of dry hollow polymer, the cationic surfactant being injected as an aqueous solution of from 10 to 50 %wt. in concentration.

11. A latex antistatic coating characterized in that said coating is formed at the temperature higher than minimum film formation temperature of the latex composition according to claims 1-7.