Title of Invention	"AN IMPROVED PROCESS FOR THE PREPARATION OF ACRYLIC COPOLYMER POWDERS BY SUSPENSION POLYMERISATION"
Abstract	The present invention relates to an improved process fro preparation of acrylic copolymers by suspension polymerization. The process steps are ; polymerising a mixture of acrylic monomers 9-15% containing soluble free radical initiators in the range of 1-10% such as herein described in 80-90% deionised water in presence of protective colloids such as polyvinyl alcohol 0.05 to 2% and chain transfer agent 0.35 to 3% such as herein described optionally in presence of anti coalescence suspending agent such as herein described at a temperature in the range of 70 to 85°C for a period in the range of 1 - 2 hrs., recovering the acrylic copolymers by known methods.

Title of Invention

"AN IMPROVED PROCESS FOR THE PREPARATION OF ACRYLIC COPOLYMER POWDERS BY SUSPENSION POLYMERISATION"

Abstract

The present invention relates to an improved process fro preparation of acrylic copolymers by suspension polymerization. The process steps are ; polymerising a mixture of acrylic monomers 9-15% containing soluble free radical initiators in the range of 1-10% such as herein described in 80-90% deionised water in presence of protective colloids such as polyvinyl alcohol 0.05 to 2% and chain transfer agent 0.35 to 3% such as herein described optionally in presence of anti coalescence suspending agent such as herein described at a temperature in the range of 70 to 85°C for a period in the range of 1 - 2 hrs., recovering the acrylic copolymers by known methods.

Full Text	The present invention relates to an improved process for preparation of acrylic copolymers by suspension polymerisation. This invention particularly relates to an improved process for the preparation of acrylic copolymer powders required for various applications in the plastics and coating industries. This invention more particularly relates to the acrylic copolymers prepared by suspension polymerisation technique especially suited for coating TV picture tubes. The Suspension polymerisation process is an important industrial process for the production of polyacrylic copolymers. A number of patents have appeared in technical literature on this subject. They are: U.S.Pats.: 2,194,354; 2,322,309; 2,445,970; 2,470,909; 2,470,910; 2,470,911; 2,476,474; 2,483,959; 2,483,960; 2,492,087; 2,492,088; 2,528,469; 2,538,050; 2,538,051; 2,511,811; 2,543,094; 2,564,291; 2,564,292; 2,580,277; 2,594,375; 2,772,257; 2,778,257; 2,875,186; 2,875,187; 2,957,857; 3,049,520 Brit.Pats.: 548,682; 627,235; 637,995; 640,120; 646,969; 658,426; 670,197; 671,446; 712,442; 745,053; 791,894. Germ.Pats.:751,602; 813,459; 826,358; 888,172; 888,173; 912,022; 947,736; 1,076,374. It. Pats.: 526,394; 532,304; 560,363; 562,180; 572,070; 643,255. The most common initiators are organic peroxide of which most frequently used is benzoyl peroxide. The polymerization temperature is generally in the range of 40-60 deg C . In most recent patents, the use of couple of suspending agents is described (U.S.Pat 2957857; 3049520).These are generally water soluble polymers such as polyvinyl alcohol, cellulose ethers, cellulose esters etc. These suspending agents also act as protective colloids. It prevents the coagulation of thee suspension and effects the size of polymer particles. The second suspending agent acts on the porosity of the polymer particles. Surprisingly, only very few studies on the controlling of the degree of polymerization have appeared in the patents. Most of the patents listed above deal with the acrylic suspension polymerization, mainly describing the initiators and various protective colloids. The degree of polymerization of acrylic copolymers required for coating TV pictures tubes should be very low, that is the molecular weight of the copolymers should be well controlled so as to give flexible coating with high adhesion. There are no patents or published literature on this subject. The main object of the present invention is to provide an improved process for the preparation of acrylic copolymer powders by suspension polymerization which obviates the drawbacks of the previous inventions. Another object is to provide a process of the present invention is to prepare acrylic copolymers of viscosity in the range of 2 to 3 CPS as 5 % solution in toluene. Yet another object of the present invention is to prepare the polymers having excellent clarity. Accordingly, the present invention provides an improved process for the preparation of acrylic copolymer powders by suspension polymerization which comprises: characterized in that polymerising a mixture of acrylic monomers 9-15% containing soluble free radical initiators in the range of 1-10% such as herein described in 80-90% deionised water in presence of protective colloids such as polyvinyl alcohol 0.05 to 2% and chain transfer agent 0.35 to 3% such as herein described optionally in presence of anti coalescence suspending agent such as herein described at a temperature in the range of 70 to 85°C for a period in the range of 1 - 2 hrs., recovering the acrylic copolymers by known methods. The present invention provides an improved process for the preparation of acrylic copolymer powders by suspension polymerization of two or more than two acrylic monomers while controlling the degree of polymerization and desired viscosity in toluene at 5% solid concentration. This was achieved by adding suitable quantities and varieties of chain transfer agents, the temperature of polymerization and by using varied percentages initiators. Such type of low molecular weight acrylic copolymers can also be used in the coating and plastic industries. In the present process, the monomers containing soluble free radical initiators were added to deionised water having suspending and protective colloids under stirring at 70 85°C as described in the examples. As the polymerization is proceeding, the polymer formed separates out from the water medium in the form of fine particles. In practice, the monomer to water ratio used is 1:5. The polymerization was allowed to proceed at this temperature for 1 - 2 h to complete the polymerization reaction. After the charge is cooled to about 40 - 50°C the suspending magnesium carbonate is converted to water soluble salt, magnesium chloride by adding dilute hydrochloric acid. The charge is then transferred to a filter press and filtered, washed with warm water to remove the protective colloid polyvinyl alcohol. The polymer powder was then dried. The size of the polymer granules formed in this process is governed by the speed of agitation which is normally maintained in this process at 300 - 400 rpm and also the type and concentration of the suspending agent. Molecular weight of the copolymers (degree of polymerization) is measured by the viscosity of the polymer solution in toluene at 5% solid concentration. This is controlled, in this process, by the temperature of the polymerisation initiator concentration, and the addition of chain transfer agents such as alkyl mercaptans, carbon tetrachloride and mixtures thereof. In an embodiment of the present invention, the monomers used may be such as isobutyl methacrylate, butylmethacrylate and methylmethacrylate. In an another embodiment of the invention, the initiators used may be monomer soluble free radical initiators and may be such as benzoyl peroxide and azobis isobutyronitrile. In an yet another embodiment of the invention, the anticoalsecence suspending agents used may be such as magensium carbonate, barium carbonate, strontium carbonate and surface treated (by stearic acid) calcium carbonate. In yet another embodiment of the invention, protective colloid or anti coalscence agents used may be such as cold water soluble polyvinyl alcohol. Still another embodiment of the invention, the chain transfer agents used may be such as carbon tetrachloride, decylmercaptan and lauryl mercaptans. To illustrate the efficacy of the present invention, various acrylic copolymer powders were prepared by suspension polymerisation technique. The acrylic copolymer powder thus prepared by the process described above has the following components: 1) Monomer mixture (a)Isobutyl methacrylate 9-15% Methyl methacrylate (70:30) (b)Butyl methacrylate 9 - 15% Methyl methacrylate(70:30) (c)Isobutyl methacrylate 9 - 15% Butyl methacrylate(70:30) 2) Free radical initiators 1-10%] 3) Suspending agents 0 - 2%] 4) Protective colloid 0.05-2%] on the total wt. of the 5) Chain transfer agents: 0.35 - 3.0% ] monomers Carbontetrachloride 0.35 - 2% ] Alkyl mercaptan 0.10-0.15%] 6) Monomer mixture to deionised 1:5- 1:10 water ratio 7) Deionised water 80-90% The following examples are given by way of illustration and therefore should not be construed to limit the scope of the present invention. EXAMPLE - 1 In a polymerisation kettle, deionised water (325ml) was taken and heated to 70°C under stirring at 3OOrpm. To this, cold water soluble polyvinyl alcohol GH17 (O.O3g) was added. When clear solution was obtained, magnesium carbonate (1.3g) was added. Monomer mixture isobutyl methacrylate (43g) and methylmethacrylate (20g) containing commercial grade benzoyl peroxide (1.3g) was added to the polymerisation kettle over a period of 30 min. The polymer is formed as fine white powder. The polymerisation was continued for a further period of one hour. The contents of the kettle were cooled to 35°C and to which 10% aqueous hydrochloric acid (100ml) was added to convert magnesium carbonate as magnesium chloride which is soluble in water. The polymer powder was filtered off and washed with deionised water (3 L), to remove the excess hydrochloric acid. The copolymer powder was then dried and weighed as 60g. Copolymer was dissolved in toluene to make a 5% solution. It has 6.7 CP viscosity. EXAMPLE-2 The procedure as given in example I is repeated by varying initiator percent benzoyl peroxide, and percent polyvinyl alcohol on the total weight of the monomers isobutyl methacrylate and methyl methacrylate. The various acrylic copolymers were obtained and the viscosity of the polymers in toluene at 5% solids was measured as shown in the following table: Copolymer Benzoylperoxide PVAGH17 Viscosity of 5% polymer (%) (%) solution in toluene (C.P) I 5 0.05 3.43 II 1 0.15 8.78 III 6 0.15 3.47 IV 7.5 0.15 3.32 V 10 0.15 3.03 EXAMPLE - 3 In a polymerisation kettle, deionised water (2800ml) was taken and heated to 80°C and in which cold water soluble polyvinyl alcohol GH17 (0.48g) was dissolved. To control the degree of polymerisation, a chain transfer agent such as carbontetrachloride CC14 (4.8ml) was added. Monomer mixture butyl methacrylate (340g) and methylmethacrylate (160g) containing commercial grade initiator benzoyl peroxide (40g) (8 wt.% on the monomer mixture) was added gradually to the reaction kettle over a period of 1 h. As the polymerisation is taking place, the copolymer as white powder was formed. The polymerisation was continued for further one hour. The copolymer powder was seperated by filtration. It was then washed with water (50°C) to remove polyvinyl alcohol from the acrylic copolymer. The copolymer powder was dried and it weighed 490g. It has a viscosity of 3.4 CP as 5% copolymer solution in toluene. In order to reduce the viscosity of the 5% copolymer solution in toluene, the quantities of benzoyl peroxide and the chain transfer agent were varied and the results are given in the following table: Copolymer Benzoylperoxide CC14 Viscosity of 5% polymer (%) (%) solution in toluene (C.P) I 5.0 1.0 4.0 II 5.0 2.0 3.8 III 8.0 1.5 3.4 IV 4.8 2.5 3.0 EXAMPLE - 4 In a polymerisation kettle deionised water (2500 ml) was taken and heated to 85°C and to this poly vinyl alcohol (lOg) (2% on the weight of the monomers) was added and dissolved. The chain transfer agent, carbontetrachloride (8ml) was then added. A monomer mixture butyl methacrylate (340g) and methylmethacrylate (160g) having benzoyl peroxide (24g) was added to the polymerisation kettle over a period of 90 minutes. The polymerisation reaction was continued for further period of 2 1/2 hours to complete the polymerisation. The speed of the agitator in the kettle was maintained between 300 - 400 rpm. The contents of the kettle were cooled to 40°C and filtered. The copolymer powder was then washed with warm water (50°C) 3 times to remove the polyvinyl alcohol. The copolymer was dried and weighed as 480g. The viscosity of this copolymer solution in toluene as 5% solids was 2.8 CP. EXAMPLE - 5 In a polymerisation kettle deionised water (1440 ml) was taken and heated to 80°C under stirring at 400rpm. To this polyvinyl alcohol GH17 (4g) was added. After obtaining clear solution, the chain transfer agents, carbontetrachloride (1ml) and lauryl (dodecyl) mercaptan 0.3g (0.11% weight on the monomer) was added. A monomer mixture isobutyl methacrylate (200g) and butylmethacrylate (80g) having benzoyl peroxide (14g) was added to the polymerisation kettle gradually over a period of Ih. The polymerisation reaction was continued for further period of 2 hours to complete the polymerisation. The white copolymer powder was seperated from the liquid by filtration and then washed with deionised water 50°C (4 L), to remove the polyvinyl alcohol. The copolymer (270g) was then obtained as dry powder. Copolymer solution in toluene as 5% solids gave viscosity of 2.5 CP. Copolymer solution in toluene as 4% solids gave as viscosity of 2.3 CP. EXAMPLE - 6 In a polymerisation kettle deionised water (1440 ml) was taken and heated to 80°C under stirring at 300rpm. Cold water soluble polyvinyl alcohol (4g) was added and after obtaining clear solution, the chain transfer agents, carbontetrachloride (Ig) and decyl mercaptan 0.3g (0.11% weight on the monomers) were added. A monomer mixture isobutyl methacrylate (200g) and butylmethacrylate (80g) having free radical initiator benzoyl peroxide (14g) was added to the polymerisation kettle gradually over a period of 1 h. The polymerisation reaction was continued for further period of 2 hours to complete the polymerisation. The contents were then cooled to 50°C and filtered. The polymer powder was then washed with hot water (40°C) (4 L), to remove the polyvinyl alcohol. The polymer was then dried and it weighed 270g. 5% polymer solution in toluene gave viscosity of 2.4 CP and 3.8% solution gave viscosity of 2.00 CP. The main advantages of this process are: 1) The acrylic copolymers of varied degrees of polymerisation (in terms of solution viscosity at 5% solids in toluene) can be made by this process of suspension polymerisation to suit to various requirements for plastics, lacquers for paints, TV picture tube coatings and as adhesives. 2) The acrylic copolymers obtained by this process could be dissolved into solvents such as toluene, xylene or butyl acetate or their combinations thereof for use as high clarity lacquers as TV picture tube coating. 3) The copolymers of butyl methacrylate, isobutyl methacrylate, and methylmethacrylate are adjusted in such a manner that their films thus obtained are soft and flexible. In this process, the chain transfer agents such as CC14, decyl mercaptan and dodecyl mercaptan are adjusted in these preparations so as to get the copolymers which can give viscosity in the range of 2.5 to 9 CP as 5% solids in toluene. 4) The protective colloids such as polyvinyl alcohol and suspending agent such as magnesium carbonate barium carbonate, strontium carbonate are used effectively to prevent the polymer powder to coalesce. 5) These acrylic copolymers powders form films of excellent clarity which are resistant to light and aging. We Claim: 1. An improved process for the preparation of acrylic copolymer powders by suspension polymerization which comprises: characterized in that polymerising a mixture of acrylic monomers 9-15% containing soluble free radical initiators in the range of 1-10% such as herein described in 80-90% deionised water in presence of protective colloids such as polyvinyl alcohol 0.05 to 2% and chain transfer agent 0.35 to 3% such as herein described, optionally in presence of anti coalescence suspending agent such as herein described at a temperature in the range of 70 to 85°C for a period in the range of 1 - 2 hrs., recovering the acrylic copolymers by known methods. 2. An improved process as claimed in claim (1) wherein the monomer mixture used are selected from isobutyl methacrylate and methyl methacrylate; butyl methacrylate and methyl methacrylate and isobutyl methacrylate and butyl methacrylate in the ratio 70:30. 3. An improved process as claimed in claims (1) & (2) wherein the monomer soluble free radical initiators used are selected from benzyol peroxide, azobisisobutyronitrile preferably in the range of 4-7% on the total weight of the monomers. 4. An improved process as claimed in claims (1) to (3) wherein the anti coalescence suspending agents used are selected from magnesium carbonate, barium carbonate, strontium carbonate in the range of 0-2% on the total weight of the monomers. 5. An improved process as claimed in claims (1) to (4) wherein the chain transfer agents to control the degree of polymerization used are selected from decyl or lauryl mercaptans , CCl4) or mixture thereof. 6. An improved process as claimed in claims (1) to (5) wherein the ratio of monomer to deionised water used is in the range of 1:5 to 1:10. 7. An improved process for the preparation of acrylic copolymer powders by suspension polymerization substantially as herein described with reference to the examples.

Full Text

The present invention relates to an improved process for preparation of acrylic
copolymers by suspension polymerisation.
This invention particularly relates to an improved process for the preparation of
acrylic copolymer powders required for various applications in the plastics and
coating industries.
This invention more particularly relates to the acrylic copolymers prepared by
suspension polymerisation technique especially suited for coating TV picture
tubes.
The Suspension polymerisation process is an important industrial process for the
production of polyacrylic copolymers. A number of patents have appeared in
technical literature on this subject. They are:
U.S.Pats.: 2,194,354; 2,322,309; 2,445,970; 2,470,909; 2,470,910; 2,470,911; 2,476,474; 2,483,959; 2,483,960; 2,492,087; 2,492,088; 2,528,469; 2,538,050; 2,538,051; 2,511,811; 2,543,094; 2,564,291; 2,564,292; 2,580,277; 2,594,375; 2,772,257; 2,778,257; 2,875,186; 2,875,187; 2,957,857; 3,049,520
Brit.Pats.: 548,682; 627,235; 637,995; 640,120; 646,969; 658,426; 670,197; 671,446; 712,442; 745,053; 791,894.
Germ.Pats.:751,602; 813,459; 826,358; 888,172; 888,173; 912,022; 947,736; 1,076,374.
It. Pats.: 526,394; 532,304; 560,363; 562,180; 572,070; 643,255.

The most common initiators are organic peroxide of which most frequently used is benzoyl peroxide. The polymerization temperature is generally in the range of 40-60 deg C . In most recent patents, the use of couple of suspending agents is described (U.S.Pat 2957857; 3049520).These are generally water soluble polymers such as polyvinyl alcohol, cellulose ethers, cellulose esters etc. These suspending agents also act as protective colloids. It prevents the coagulation of thee suspension and effects the size of polymer particles. The second suspending agent acts on the porosity of the polymer particles. Surprisingly, only very few studies on the controlling of the degree of polymerization have appeared in the patents. Most of the patents listed above deal with the acrylic suspension polymerization, mainly describing the initiators and various protective colloids. The degree of polymerization of acrylic copolymers required for coating TV pictures tubes should be very low, that is the molecular weight of the copolymers should be well controlled so as to give flexible coating with high adhesion. There are no patents or published literature on this subject. The main object of the present invention is to provide an improved process for the preparation of acrylic copolymer powders by suspension polymerization which obviates the drawbacks of the previous inventions.
Another object is to provide a process of the present invention is to prepare acrylic copolymers of viscosity in the range of 2 to 3 CPS as 5 % solution in toluene. Yet another object of the present invention is to prepare the polymers having excellent clarity.
Accordingly, the present invention provides an improved process for the preparation of acrylic copolymer powders by suspension polymerization which comprises: characterized in that polymerising a mixture of acrylic monomers 9-15% containing

soluble free radical initiators in the range of 1-10% such as herein described in 80-90% deionised water in presence of protective colloids such as polyvinyl alcohol 0.05 to 2% and chain transfer agent 0.35 to 3% such as herein described optionally in presence of anti coalescence suspending agent such as herein described at a temperature in the range of 70 to 85°C for a period in the range of 1 - 2 hrs., recovering the acrylic copolymers by known methods.
The present invention provides an improved process for the preparation of acrylic copolymer powders by suspension polymerization of two or more than two acrylic monomers while controlling the degree of polymerization and desired viscosity in toluene at 5% solid concentration. This was achieved by adding suitable quantities and varieties of chain transfer agents, the temperature of polymerization and by using varied percentages initiators. Such type of low molecular weight acrylic copolymers can also be used in the coating and plastic industries.
In the present process, the monomers containing soluble free radical initiators were added to deionised water having suspending and protective colloids under stirring at 70 85°C as described in the examples. As the polymerization is proceeding, the polymer formed separates out from the water medium in the form of fine particles. In practice, the monomer to water ratio used is 1:5. The polymerization was allowed to proceed at this temperature for 1 - 2 h to complete the polymerization reaction. After the charge is cooled to about 40 - 50°C the suspending magnesium carbonate is converted to water soluble salt, magnesium chloride by adding dilute hydrochloric acid. The charge is then transferred to a filter press and filtered, washed with warm water to remove the protective colloid polyvinyl alcohol. The polymer powder was then dried.
The size of the polymer granules formed in this process is governed by the speed of agitation which is normally maintained in this process at 300 - 400 rpm and also the type and concentration of the suspending agent. Molecular weight of the copolymers (degree of polymerization) is measured by the viscosity of the

polymer solution in toluene at 5% solid concentration. This is controlled, in this
process, by the temperature of the polymerisation initiator concentration, and the
addition of chain transfer agents such as alkyl mercaptans, carbon tetrachloride
and mixtures thereof.
In an embodiment of the present invention, the monomers used may be such as
isobutyl methacrylate, butylmethacrylate and methylmethacrylate.
In an another embodiment of the invention, the initiators used may be monomer
soluble free radical initiators and may be such as benzoyl peroxide and azobis
isobutyronitrile.
In an yet another embodiment of the invention, the anticoalsecence suspending
agents used may be such as magensium carbonate, barium carbonate, strontium
carbonate and surface treated (by stearic acid) calcium carbonate.
In yet another embodiment of the invention, protective colloid or anti coalscence
agents used may be such as cold water soluble polyvinyl alcohol.
Still another embodiment of the invention, the chain transfer agents used may be
such as carbon tetrachloride, decylmercaptan and lauryl mercaptans.
To illustrate the efficacy of the present invention, various acrylic copolymer
powders were prepared by suspension polymerisation technique.
The acrylic copolymer powder thus prepared by the process described above has
the following components:
1) Monomer mixture
(a)Isobutyl methacrylate 9-15%
Methyl methacrylate (70:30)
(b)Butyl methacrylate 9 - 15%
Methyl methacrylate(70:30)
(c)Isobutyl methacrylate 9 - 15%

Butyl methacrylate(70:30)
2) Free radical initiators 1-10%]
3) Suspending agents 0 - 2%]
4) Protective colloid 0.05-2%] on the total wt. of the
5) Chain transfer agents: 0.35 - 3.0% ] monomers
Carbontetrachloride 0.35 - 2% ]
Alkyl mercaptan 0.10-0.15%]
6) Monomer mixture to deionised 1:5- 1:10
water ratio
7) Deionised water 80-90%
The following examples are given by way of illustration and therefore should not be construed to limit the scope of the present invention.
EXAMPLE - 1
In a polymerisation kettle, deionised water (325ml) was taken and heated to 70°C under stirring at 3OOrpm. To this, cold water soluble polyvinyl alcohol GH17 (O.O3g) was added. When clear solution was obtained, magnesium carbonate (1.3g) was added. Monomer mixture isobutyl methacrylate (43g) and methylmethacrylate (20g) containing commercial grade benzoyl peroxide (1.3g) was added to the polymerisation kettle over a period of 30 min. The polymer is formed as fine white powder. The polymerisation was continued for a further period of one hour. The contents of the kettle were cooled to 35°C and to which 10% aqueous hydrochloric acid (100ml) was added to convert magnesium carbonate as magnesium chloride which is soluble in water. The polymer powder was filtered off and washed with deionised water (3 L), to remove the excess hydrochloric acid. The copolymer powder was then dried and weighed as 60g. Copolymer was dissolved in toluene to make a 5% solution. It has 6.7 CP viscosity.

EXAMPLE-2
The procedure as given in example I is repeated by varying initiator percent benzoyl peroxide, and percent polyvinyl alcohol on the total weight of the monomers isobutyl methacrylate and methyl methacrylate. The various acrylic copolymers were obtained and the viscosity of the polymers in toluene at 5% solids was measured as shown in the following table:
Copolymer Benzoylperoxide PVAGH17 Viscosity of 5% polymer
(%) (%) solution in toluene
(C.P)
I 5 0.05 3.43
II 1 0.15 8.78
III 6 0.15 3.47
IV 7.5 0.15 3.32
V 10 0.15 3.03
EXAMPLE - 3
In a polymerisation kettle, deionised water (2800ml) was taken and heated to 80°C and in which cold water soluble polyvinyl alcohol GH17 (0.48g) was dissolved. To control the degree of polymerisation, a chain transfer agent such as carbontetrachloride CC14 (4.8ml) was added. Monomer mixture butyl methacrylate (340g) and methylmethacrylate (160g) containing commercial grade initiator benzoyl peroxide (40g) (8 wt.% on the monomer mixture) was added gradually to the reaction kettle over a period of 1 h. As the polymerisation is taking place, the copolymer as white powder was formed. The polymerisation was continued for further one hour. The copolymer powder was seperated by filtration. It was then washed with water (50°C) to remove polyvinyl alcohol from the acrylic copolymer. The copolymer powder was dried and it weighed 490g. It has a viscosity of 3.4 CP as 5% copolymer solution in toluene. In order to reduce the viscosity of the 5% copolymer solution in toluene, the quantities of benzoyl

peroxide and the chain transfer agent were varied and the results are given in the following table:
Copolymer Benzoylperoxide CC14 Viscosity of 5% polymer
(%) (%) solution in toluene
(C.P)
I 5.0 1.0 4.0
II 5.0 2.0 3.8
III 8.0 1.5 3.4
IV 4.8 2.5 3.0
EXAMPLE - 4
In a polymerisation kettle deionised water (2500 ml) was taken and heated to 85°C and to this poly vinyl alcohol (lOg) (2% on the weight of the monomers) was added and dissolved. The chain transfer agent, carbontetrachloride (8ml) was then added. A monomer mixture butyl methacrylate (340g) and methylmethacrylate (160g) having benzoyl peroxide (24g) was added to the polymerisation kettle over a period of 90 minutes. The polymerisation reaction was continued for further period of 2 1/2 hours to complete the polymerisation. The speed of the agitator in the kettle was maintained between 300 - 400 rpm. The contents of the kettle were cooled to 40°C and filtered. The copolymer powder was then washed with warm water (50°C) 3 times to remove the polyvinyl alcohol. The copolymer was dried and weighed as 480g. The viscosity of this copolymer solution in toluene as 5% solids was 2.8 CP.

EXAMPLE - 5
In a polymerisation kettle deionised water (1440 ml) was taken and heated to 80°C under stirring at 400rpm. To this polyvinyl alcohol GH17 (4g) was added. After obtaining clear solution, the chain transfer agents, carbontetrachloride (1ml) and lauryl (dodecyl) mercaptan 0.3g (0.11% weight on the monomer) was added. A monomer mixture isobutyl methacrylate (200g) and butylmethacrylate (80g) having benzoyl peroxide (14g) was added to the polymerisation kettle gradually over a period of Ih. The polymerisation reaction was continued for further period of 2 hours to complete the polymerisation. The white copolymer powder was seperated from the liquid by filtration and then washed with deionised water 50°C (4 L), to remove the polyvinyl alcohol. The copolymer (270g) was then obtained as dry powder. Copolymer solution in toluene as 5% solids gave viscosity of 2.5 CP. Copolymer solution in toluene as 4% solids gave as viscosity of 2.3 CP.
EXAMPLE - 6
In a polymerisation kettle deionised water (1440 ml) was taken and heated to 80°C under stirring at 300rpm. Cold water soluble polyvinyl alcohol (4g) was added and after obtaining clear solution, the chain transfer agents, carbontetrachloride (Ig) and decyl mercaptan 0.3g (0.11% weight on the monomers) were added. A monomer mixture isobutyl methacrylate (200g) and butylmethacrylate (80g) having free radical initiator benzoyl peroxide (14g) was added to the polymerisation kettle gradually over a period of 1 h. The polymerisation reaction was continued for further period of 2 hours to complete the polymerisation. The contents were then cooled to 50°C and filtered. The polymer powder was then washed with hot water (40°C) (4 L), to remove the polyvinyl alcohol. The

polymer was then dried and it weighed 270g. 5% polymer solution in toluene gave viscosity of 2.4 CP and 3.8% solution gave viscosity of 2.00 CP. The main advantages of this process are:
1) The acrylic copolymers of varied degrees of polymerisation (in terms of
solution viscosity at 5% solids in toluene) can be made by this process of
suspension polymerisation to suit to various requirements for plastics,
lacquers for paints, TV picture tube coatings and as adhesives.
2) The acrylic copolymers obtained by this process could be dissolved into
solvents such as toluene, xylene or butyl acetate or their combinations
thereof for use as high clarity lacquers as TV picture tube coating.
3) The copolymers of butyl methacrylate, isobutyl methacrylate, and
methylmethacrylate are adjusted in such a manner that their films thus
obtained are soft and flexible. In this process, the chain transfer agents
such as CC14, decyl mercaptan and dodecyl mercaptan are adjusted in
these preparations so as to get the copolymers which can give viscosity
in the range of 2.5 to 9 CP as 5% solids in toluene.
4) The protective colloids such as polyvinyl alcohol and suspending agent
such as magnesium carbonate barium carbonate, strontium carbonate
are used effectively to prevent the polymer powder to coalesce.
5) These acrylic copolymers powders form films of excellent clarity which
are resistant to light and aging.

We Claim:
1. An improved process for the preparation of acrylic copolymer powders by suspension
polymerization which comprises: characterized in that polymerising a mixture of acrylic
monomers 9-15% containing soluble free radical initiators in the range of 1-10% such as
herein described in 80-90% deionised water in presence of protective colloids such as
polyvinyl alcohol 0.05 to 2% and chain transfer agent 0.35 to 3% such as herein
described, optionally in presence of anti coalescence suspending agent such as herein
described at a temperature in the range of 70 to 85°C for a period in the range of 1 - 2
hrs., recovering the acrylic copolymers by known methods.
2. An improved process as claimed in claim (1) wherein the monomer mixture used are
selected from isobutyl methacrylate and methyl methacrylate; butyl methacrylate and
methyl methacrylate and isobutyl methacrylate and butyl methacrylate in the ratio 70:30.
3. An improved process as claimed in claims (1) & (2) wherein the monomer soluble free
radical initiators used are selected from benzyol peroxide, azobisisobutyronitrile
preferably in the range of 4-7% on the total weight of the monomers.
4. An improved process as claimed in claims (1) to (3) wherein the anti coalescence
suspending agents used are selected from magnesium carbonate, barium carbonate,
strontium carbonate in the range of 0-2% on the total weight of the monomers.
5. An improved process as claimed in claims (1) to (4) wherein the chain transfer agents to
control the degree of polymerization used are selected from decyl or lauryl mercaptans ,
CCl4) or mixture thereof.
6. An improved process as claimed in claims (1) to (5) wherein the ratio of monomer to
deionised water used is in the range of 1:5 to 1:10.
7. An improved process for the preparation of acrylic copolymer powders by suspension
polymerization substantially as herein described with reference to the examples.

Documents:

261-del-2000-abstract.pdf

261-del-2000-claims.pdf

261-del-2000-correspondence-others.pdf

261-del-2000-correspondence-po.pdf

261-del-2000-description (complete).pdf

261-del-2000-form-1.pdf

261-del-2000-form-19.pdf

261-del-2000-form-2.pdf

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Patent Number

230946

Indian Patent Application Number

261/DEL/2000

PG Journal Number

13/2009

Publication Date

27-Mar-2009

Grant Date

28-Feb-2009

Date of Filing

16-Mar-2000

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG, NEW DELHI-110001, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	NORI KRISHNAMURTI	INDIAN INSTITUTE OF CHEMICAL TECHNOLOGY HYDERABD-500007, ANDHRA PRADESH INDIA.
2	BHAMTDIPALLI SUBRAMANYA SITARAMAM	INDIAN INSTITUTE OF CHEMICAL TECHNOLOGY HYDERABD-500007, ANDHRA PRADESH INDIA.
3	DEEKSHITULA BHASKARA ROHINI KUMAR	INDIAN INSTITUTE OF CHEMICAL TECHNOLOGY HYDERABD-500007, ANDHRA PRADESH INDIA.

PCT International Classification Number

C08J 3/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA