Continuous process for preparing polymers

Example 1

[0032] A monomer mixture (46% butyl acrylate, 53% methyl methacrylate, 1% methacrylic acid) was fed at 58.5 g/min from a 3.6 L tank to an evacuated premixer (Cornell Model D-8 Versator with a vacuum of 55.9 mm(22 in) water). An aqueous mixture (1.4% anionic surfactant) was fed at 11.4 g/min from a 7.6 L tank to the pre-mixer. The pre-mixer was set to a speed such that a stable monomer emulsion was produced. A 20 L aqueous feed tank was used to feed hot DI water to the front of the process. A 10% ammonium persulfate catalyst solution was prepared. The solution was mixed well and fed to the catalyst feed tank. A 1.2% aqueous ammonia/13.8% sodium laurel sulfate buffer solution was prepared. The solution was mixed well and fed to the buffer feed tank. The aqueous feeds were fed through 18 feet of peroxide cured gas permeable tubing coiled in an evacuated chamber at 61.0 mm(24 in) water. The aqueous catalyst feed tanks were sparged with N2. The buffer feed tank was swept with N2.

[0033] DI water was heated to 95.degree. C. A Tranter UFX-6 plate-frame heat exchanger system was utilized as the reactor. The water was pumped through the process lines in order to heat the system. The temperature for the "water-side" of the reactors was then set to 70.degree. C. Tempered water flow through the "water-side" was begun. The reactor temperature was allowed to equilibrate.

[0034] The DI water flow was adjusted to 64.8 g/min. The catalyst pump was turned on to 5.68 ml/min and steam was injected into the catalyst line to preheat the mixture to 95.degree. C. The buffer pump was turned on to 11.03 ml/min. The monomer emulsion feed was introduced before the reactor at a rate of 18.5 g/min. The temperature of the water in the heating bath that fed a pipe in pipe heat exchanger on the aqueous feed line was adjusted to insure that the temperature of the emulsion at the heat exchanger inlet was approximately 73.degree. C. The monomer emulsion was fed continuously to the heat exchangers. The monomer was polymerized in the heat exchangers. Polymer was continuously removed from the heat exchangers and collected and cooled in the final product holding tank. When the volume was low in any of the feed tanks it was replenished with a charge equivalent to the original. After 4 hours of running, warm soapy water was pumped through the system in order to flush out any remaining emulsion. This was continued until the exiting liquid was clear.

[0035] A stable latex with a 17.9% solids content and a mean weight average particle diameter of 55 nm was obtained as a product. The polydispersity of the product was 1.06. Reaction totaled 100% conversion. The system was dismantled and the plates were weighed. The plates weighed 23 grams more than before the experiment.

[0036] Comparative Example A

[0037] A monomer mixture (46% butyl acrylate, 53% methyl methacrylate, 1% methacrylic acid) was fed at 58.5 g/min from a 3.6 L tank to a vented premixer (Cornell Model D-8 Versator with no vacuum applied). An aqueous mixture (1.4% anionic surfactant) was fed at 11.4 g/min from a 7.6 L tank to the pre-mixer. The pre-mixer was set to a speed such that a stable monomer emulsion was produced. A 20 L aqueous feed tank was used to feed hot DI water to the front of the process. A 10% ammonium persulfate catalyst solution was prepared. The solution was mixed well and fed to the catalyst feed tank. A 1.2% aqueous ammonia/13.8% sodium laurel sulfate buffer solution was prepared. The solution was mixed well and fed to the buffer feed tank. The aqueous feeds were fed through 18 feet of peroxide cured gas permeable tubing coiled in a vented chamber with no vaccum applied. The aqueous, catalyst feed tanks were sparged with N2. The buffer feed tank was swept with N2.

[0038] DI water was heated to 95.degree. C. A Tranter UFX-6 plate-frame heat exchanger system was utilized as the reactor. The water was pumped through the process lines in order to heat the system. The temperature for the "water-side" of the reactors was then set to 70.degree. C. Tempered water flow through the "water-side" was begun. The reactor temperature was allowed to equilibrate.

[0039] The DI water flow was adjusted to 64.8 g/min. The catalyst pump was turned on to 5.68 ml/min and steam was injected into the catalyst line to preheat the mixture to 95.degree. C. The buffer pump was turned on to 11.03 ml/min. The monomer emulsion feed was introduced before the reactor at a rate of 18.5 g/min. The temperature of the water in the heating bath that fed a pipe in pipe heat exchanger on the aqueous feed line was adjusted to insure that the temperature of the emulsion at the heat exchanger inlet was approximately 73.degree. C. The monomer emulsion was fed continuously to the heat exchangers. The monomer was polymerized in the heat exchangers. Polymer was continuously removed from the heat exchangers and collected and cooled in the final product holding tank. When the volume was low in any of the feed tanks it was replenished with a charge equivalent to the original. After 4 hours of running, warm soapy water was pumped through the system in order to flush out any remaining emulsion. This was continued until the exiting liquid was clear.

[0040] A stable latex with a 18.2% solids content and a mean weight average particle diameter of 56.5 nm was obtained as a product. The polydispersity of the product was 1.06. Reaction totaled 100% conversion. The system was dismantled and the plates were weighed. The plates weighed 49 grams more than before the experiment, i.e., more fouling was observed on the first plate channels for Comparative Example A than in Example 1 of this invention.

Example 2

[0041] A monomer mixture (46% butyl acrylate, 53% methyl methacrylate, 1% methacrylic acid) was fed at 58.5 g/min from a 3.6 L tank to an evacuated premixer (Cornell Model D-8 Versator with a vacuum of 55.9 mm (22 in) water). An aqueous mixture (1.4% anionic surfactant) was fed at 11.4 g/min from a 7.6 L tank to the pre-mixer. The pre-mixer was set to a speed such that a stable monomer emulsion was produced. A 20 L aqueous feed tank was used to feed hot DI water to the front of the process. A 10% ammonium persulfate catalyst solution was prepared. The solution was mixed well and fed to the catalyst feed tank. A 1.2% aqueous ammonia/13.8% sodium laurel sulfate buffer solution was prepared. The solution was mixed well and fed to the buffer feed tank. The aqueous feeds were fed through 18 feet of peroxide cured gas permeable tubing coiled in an evacuated chamber at 61.0 mm (24 in) water. The aqueous tanks were sparged with Helium. The buffer feed and catalyst tanks were swept with Helium.

[0042] DI water was heated to 95.degree. C. A Tranter UFX-6 plate-frame heat exchanger system was utilized as the reactor. The water was pumped through the process lines in order to heat the system. The temperature for the "water-side" of the reactors was then set to 70.degree. C. Tempered water flow through the "water-side" was begun. The reactor temperature was allowed to equilibrate.

[0043] The DI water flow was adjusted to 64.8 g/min. The catalyst pump was turned on to 5.68 ml/min. The buffer pump was turned on to 11.03 ml/min. The monomer emulsion feed was introduced before the reactor at a rate of 18.5 g/min. The temperature of the water in the heating bath that fed a pipe in pipe heat exchanger on the aqueous feed line was adjusted to insure that the temperature of the emulsion at the heat exchanger inlet was approximately 73.degree. C. The monomer emulsion was fed continuously to the heat exchangers. The monomer was polymerized in the heat exchangers. Polymer was continuously removed from the heat exchangers and collected and cooled in the final product holding tank. When the volume was low in any of the feed tanks it was replenished with a charge equivalent to the original. After 4 hours of running, warm soapy water was pumped through the system in order to flush out any remaining emulsion. This was continued until the exiting liquid was clear.

[0044] A stable latex with a 17.1% solids content and a mean weight average particle diameter of 56 nm was obtained as a product. The polydispersity of the product was 1.05. Reaction totaled 100% conversion. The system was dismantled and the plates were weighed. The plates weighed 20 grams more than before the experiment.

Example 3

[0045] A monomer mixture (46% butyl acrylate, 53% methyl methacrylate, 1% methacrylic acid) was fed at 58.5 g/min from a 3.6 L tank to an evacuated premixer (Cornell Model D-8 Versator with a vacuum of 55.9 mm (22 in) water). An aqueous mixture (1.4% anionic surfactant) was fed at 11.4 g/min from a 7.6 L tank to the pre-mixer. The pre-mixer was set to a speed such that a stable monomer emulsion was produced. A 20 L aqueous feed tank was used to feed hot DI water to the front of the process. A 10% ammonium persulfate catalyst solution was prepared. The solution was mixed well and fed to the catalyst feed tank. A 1.2% aqueous ammonia/13.8% sodium laurel sulfate buffer solution was prepared. The solution was mixed well and fed to the buffer feed tank. The aqueous feeds were fed through 18 feet of peroxide cured gas permeable tubing coiled in an evacuated chamber at 24" water. The aqueous, catalyst feed tanks were sparged with N2. The buffer feed tank was swept with N2.

[0046] DI water was heated to 95.degree. C. A Tranter UFX-6 plate-frame heat exchangers system was utilized as the reactor. The water was pumped through the process lines in order to heat the system. The temperature for the "water-side" of the reactors was then set to 70.degree. C. Tempered water flow through the "water-side" was begun. The reactor temperature was allowed to equilibrate.

[0047] The DI water flow was adjusted to 64.8 g/min. The catalyst pump was turned on to 5.68 ml/min. The buffer pump was turned on to 11.03 ml/min. The monomer emulsion feed was introduced before the reactor at a rate of 18.5 g/min. The temperature of the water in the heating bath that fed a pipe in pipe heat exchanger on the aqueous feed line was adjusted to insure that the temperature of the emulsion at the heat exchanger inlet was approximately 73.degree. C. The monomer emulsion was fed continuously to the heat exchangers. The monomer was polymerized in the heat exchangers. Polymer was continuously removed from the heat exchangers and collected and cooled in the final product holding tank. When the volume was low in any of the feed tanks it was replenished with a charge equivalent to the original. After 4 hours of running, warm soapy water was pumped through the system in order to flush out any remaining emulsion. This was continued until the exiting liquid was clear.

[0048] A stable latex with a 17.5% solids content and a mean weight average particle diameter of 55 nm was obtained as a product. The polydispersity of the product was 1.06. Reaction totaled 100% conversion. The system was dismantled and the plates were weighed. The plates weighed 16 grams more than before the experiment.