DESC:FIELD
The present disclosure relates to an acrylic silicone emulsion and a process for its preparation.
DEFINITIONS
As used in the present disclosure, the following terms are generally intended to have the meaning as set forth below, except to the extent that the context in which they are used indicates otherwise.
Dirt pickup resistance (DPUR) refers to an ability of a coating/paint to maintain its original appearance with respect to soiling of the surface due to exterior environmental conditions.
Crack bridging ability (CBA) refers to an ability of a coating/paint of bridging over cracks and maintaining a continuous film.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
The acrylic silicone emulsion based coatings have properties such as water repellency, water resistance, weatherability, gloss retention, stain resistance, UV resistance, scrub resistance, adhesion properties and the like. The acrylic silicone emulsion has huge commercial applications in water-based decorative and industrial paints, coatings and adhesives. The acrylic silicone emulsions can also be used in varnish, stone coatings, textile coatings, paper processing agent, especially as a paint or finish coat for building materials such as interior and high weatherability exterior wall coatings, and adhesives and sealants such as liquid emulsion adhesives, hot-melt adhesives, flame retardant adhesives, pressure sensitive adhesives and the like.
The preparation of acrylic silicone emulsion is well known in the art. Generally, the conventional methods for the preparation of acrylic silicone emulsions require longer processing time and employs separate addition of silane monomers. Due to the separate addition of silane monomers, the silane monomers are difficult to stabilize in the pre-emulsion of acrylic monomers which leads to the formation of unreacted silicone oligomers with oily layer on the top of the emulsion. Thus, in conventional acrylic silicone emulsions, there is incomplete grafting of silicone in the acrylic back-bone.
Further, the conventional acrylic silicone emulsions have high cross-linking density and hence, are less flexible or even if made flexible then have poor dirt pickup resistance (DPUR). In addition, the conventional acrylic silicone emulsion with high acid content when used with other emulsions as a blend, it creates problem such as viscosity pickup, gelation and poor shelf stability (due to use of high acid content for stabilization).
Therefore, there is felt a need to develop an acrylic silicone emulsion that can mitigate the drawbacks mentioned herein above or at least provide a useful alternative.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows.
An object of the present disclosure is to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
Another object of the present disclosure is to provide an acrylic silicone emulsion.
Yet another object of the present disclosure is to provide an acrylic silicone emulsion that results in high dirt pickup resistance (DPUR) along with excellent crack bridging ability (CBA) in coating.
Still another object of the present disclosure is to provide a simple and an environment friendly process for the preparation of an acrylic silicone emulsion.
Yet another object of the present disclosure is to provide a coating composition comprising an acrylic silicone emulsion.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure relates to an acrylic silicone emulsion. The acrylic silicone emulsion is a reaction product of at least one acrylic monomer, at least one silane monomer, an acid, an initiator, a surface active agent, at least one chaser catalyst, at least one additive and water.
The present disclosure further relates to a process for the preparation of an acrylic silicone emulsion. The process comprises a step of charging first predetermined amounts of a surface active agent and water in a reactor followed by heating the reactor at a first predetermined temperature to obtain a first solution. A predetermined amount of an initiator is added to the first solution in the reactor at the first predetermined temperature to obtain a second solution. First predetermined amounts of at least one acrylic monomer and an acid are added gradually to the second solution under stirring over a first predetermined time period followed by reacting at a second predetermined temperature for a second predetermined time period to obtain a third solution. Separately, second predetermined amounts of at least one acrylic monomer, the acid, the surface active agent, water and a predetermined amount of at least one silane monomer are mixed under stirring to obtain a pre-emulsion. The pre-emulsion is gradually added to the third solution under stirring in the reactor over a third predetermined time period followed by reacting for a fourth predetermined time period to obtain a fourth solution. The fourth solution in the reactor is cooled to temperature in the range of 50 ºC to 70 °C followed by adding a predetermined amount of at least one chaser catalyst to the fourth solution under stirring and continuing stirring for a fifth time period to obtain a fifth solution. The fifth solution in the reactor is cooled to a temperature in the range of 30 ºC to 50 °C followed by adding a predetermined amount of additive under stirring and continuing stirring for a sixth predetermined time period to obtain the acrylic silicone emulsion.
DETAILED DESCRIPTION
The present disclosure relates to an acrylic silicone emulsion and a process for its preparation.
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising," “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.
Generally, the conventional methods for the preparation of acrylic silicone emulsions require longer processing time and employs separate addition of silane monomers. Due to the separate addition of silane monomers, the silane monomers are difficult to stabilize in the pre-emulsion of acrylic monomers which leads to the formation of unreacted silicone oligomers with oily layer on the top of the emulsion. Thus, in conventional acrylic silicone emulsions, there is incomplete grafting of silicone in the acrylic back-bone. Further, no single acrylic silicone emulsion is reported to provide the properties of high dirt-pickup resistance (DPUR) and high crack bridging ability at a time. The conventional acrylic silicone emulsions have high cross-linking density and hence, are less flexible or even if made flexible then have poor dirt pickup resistance (DPUR). Hence, there is need of acrylic silicone emulsions of controlled crosslinking density with stable viscosity and 100 % conversion of silane monomers.
As the single or blend of the commercially available acrylic silicone emulsions are not having the balanced property between dirt-pickup resistance (DPUR) and elongation along with extraordinary crack-bridging ability (CBA), there is a room for the development of a blend system of an acrylic silicone emulsion to obtain the balance property between dirt-pickup resistance (DPUR) and elongation along with extraordinary crack-bridging ability (CBA).
The present disclosure provides an acrylic silicone emulsion and a process for its preparation.
The present disclosure provides an acrylic silicone emulsion that has high dust pickup resistance (DPUR) along with high elongation and hence high crack bridging ability (CBA).
In an aspect, the present disclosure provides an acrylic silicone emulsion. The emulsion is a reaction product of:
a. at least one acrylic monomer;
b. at least one silane monomer;
c. an acid;
d. an initiator;
e. a surface active agent;
f. at least one chaser catalyst;
g. at least one additive; and
h. water.
In an embodiment of the present disclosure, the acrylic silicone emulsion comprises:
a. 30 mass% to 50 mass% of the acrylic monomer;
b. 2 mass% to 10 mass % of the silane monomer;
c. 0.05 mass% to 1.0 mass% of the acid;
d. 0.01 mass% to 0.2 mass% of said initiator;
e. 0.5 mass% to 2 mass% of the surface active agent;
f. 0.01 mass% to 0.2 mass% of the chaser catalyst;
g. 0.1 mass% to 2 mass% of the additive; and
h. q.s. water,
wherein the mass% of each component is with respect to the total mass of the emulsion.
In an embodiment of the present disclosure, a mass ratio of the acrylic monomer to the silane monomer is in the range of 93:7 to 80:20 (i.e. 4:1 to 13.2:1). In an exemplary embodiment of the present disclosure, the mass ratio of the acrylic monomer to the silane monomer is 9.40:1. In another exemplary embodiment of the present disclosure, the mass ratio of the acrylic monomer to the silane monomer is 11.87:1. In yet another exemplary embodiment of the present disclosure, the mass ratio of the acrylic monomer to the silane monomer is 10.27:1.

The mass ratio of the acrylic monomer to the silane monomer plays an important role in achieving the desirable properties of the acrylic silicon emulsion. This mass ratio indicates the number of silane moieties that can be attached in the acrylic backbone. The mass ratio of the acrylic monomer to the silane monomer in the range of 93:7 to 80:20 (i.e. 4:1 to 13.2:1) was found to be the optimum ratio for obtaining a stable acrylic silicon emulsion and thus, providing required properties to the acrylic silicon emulsion of the present disclosure. In contrast, if the mass ratio is less or more than the disclosed range, than the emulsion obtained is either unstable or does not provide the required properties to the emulsion or both.
In accordance with the present disclosure, the acrylic monomer can be at least one selected from the group consisting of methyl methacrylate, n-butyl acrylate, n-butyl methacrylate, lauryl methacrylate, stearyl methacrylate and 2-ethyl hexyl acrylate. In accordance with an exemplary embodiment of the present disclosure, the acrylic monomers are methyl methacrylate and butyl acrylate. In accordance with another exemplary embodiment of the present disclosure, the acrylic monomers are methyl methacrylate, butyl acrylate and lauryl methacrylate. In yet another exemplary embodiment of the present disclosure, the acrylic monomers are methacrylate, butyl acrylate and stearyl methacrylate. In an exemplary embodiment of the present disclosure, the amount of the acrylic monomers is 38 mass% with respect to the total mass of the emulsion.
In accordance with the present disclosure, the silane monomer can be at least one selected from the group consisting of methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, n-butyltrimethoxysilane, n-hexyltrimethoxysilane, n-octyltrimethoxysilane, n-decyltrimethoxysilane, n-dodecyltrimethoxysilane, hexadecyltrimethoxysilane, octadecyltrimethoxysilane, 3-acryloxy-1-propyltrimethoxysilane and 3-methacryloxy-1-propyltrimethoxy silane. In accordance with an exemplary embodiment of the present disclosure, silane monomers are methacryloxypropyltrimethoxysilane and dimethyldimethoxysilane. In an exemplary embodiment of the present disclosure, the predetermined amount of the silane monomer is 4.2 mass% with respect to the total mass of the emulsion. In another exemplary embodiment of the present disclosure, the predetermined amount of the silane monomer is 2.2 mass% with respect to the total mass of the emulsion. In yet another exemplary embodiment of the present disclosure, the predetermined amount of the silane monomer is 3.2 mass% with respect to the total mass of the emulsion.
In accordance with the present disclosure, the acid is acrylic acid, preferably, methacrylic acid. In an exemplary embodiment of the present disclosure, the amount of acid is 0.3 mass% with respect to the total mass of the emulsion.
In accordance with the embodiment of the present disclosure, the acrylic/methacrylic acid is used in an optimum quantity required for the hydrolysis and the condensation of the silane monomer to obtain a stable acrylic silicone emulsion.
The conventional acrylic silicone emulsions are stabilized by acids. Due to the use of high acid content in the emulsion (for stabilization), it creates problem such as viscosity pickup, gelation and poor shelf stability, when used with other emulsions. However, in the acrylic silicone emulsion of the present disclosure, the acid content is optimized and stabilized by proper hydrolysis and condensation of silanes such that the emulsion of the present disclosure that can be used with any other emulsion that results in excellent stability.
In accordance with the present disclosure, the initiator can be selected from the group consisting of ammonium persulfate, potassium persulfate and azobisisobutyronitrile (AIBN). In an exemplary embodiment of the present disclosure, the initiator is ammonium persulfate. In an exemplary embodiment of the present disclosure, the predetermined amount of the initiator is 0.12 mass% with respect to the total mass of the emulsion.
In accordance with the present disclosure, the surface active agent can be selected from the group consisting of succinic acid ester based sodium sulfonate, sodium alkyl allyl sulfosuccinate and adipic acid ester based sodium sulfonates. In an exemplary embodiment of the present disclosure, the surface active agent is sodium alkyl allyl sulfosuccinate. In an exemplary embodiment of the present disclosure, the amount of the surface active agent is 1.20 mass% with respect to the total mass of the emulsion.
In accordance with the present disclosure, the chaser catalyst is at least one selected from the group consisting of tertiary butyl hydroperoxide, sodium formaldehyde sulphoxalate, sodium metabisulphate, hydrogen peroxide and tartaric acid. In an exemplary embodiment of the present disclosure, the chaser catalysts are tertiary butyl hydroperoxide and sodium formaldehyde sulphoxalate. In an exemplary embodiment of the present disclosure, the amount of the chaser catalyst is 0.1 mass% with respect to the total mass of the emulsion.
The use of the combination of the chaser catalysts i.e. tertiary butyl hydroperoxide (TBHP) and sodium formaldehyde sulphoxalate (SFS) increases the catalytic activity as these are the redox chaser catalysts, wherein one act as oxidizing agent (TBHP) and another as a reducing agent (SFS). These catalysts when used in combination help to accelerate the reaction.
In accordance with an embodiment of the present disclosure, the additive is at least one selected from the group consisting of:
• a pH adjusting agent;
• a defoaming agent; and
• a biocide.
The pH adjusting agent can be selected from the group consisting of liquor ammonia, sodium hydroxide and potassium hydroxide. In an exemplary embodiment of the present disclosure, the pH adjusting agent is a liquor ammonia. In an exemplary embodiment of the present disclosure, the predetermined amount of the pH adjusting agent is 1.0 mass% with respect to the total mass of the emulsion.
The defoaming agent can be selected from the group consisting of polyether siloxane based defoamer, polyester siloxane based defoamer and long chain fatty acid silicone modified defoamer. In an exemplary embodiment of the present disclosure, the defoaming agent is polyether siloxane based defoamer. In an exemplary embodiment of the present disclosure, the predetermined amount of the defoaming agent is 0.1 mass% with respect to the total mass of the emulsion.
The biocide can be selected from the group consisting of 1,2-benzisothiazolin-3-one, methylisothiazolinone, methylchloro-isothiazolinone, octylisothiazolinone, dicholoro-octylisothiazolinone, chloromethyl isothiazolinone and butyl benzisothiazolinone. In an exemplary embodiment of the present disclosure, the biocide is 1,2-benzisothiazolin-3-one. In an exemplary embodiment of the present disclosure, the predetermined amount of the biocide is 0.2 mass% with respect to the total mass of the emulsion.
In another aspect, the present disclosure provides a process for the preparation of an acrylic silicone emulsion.
The process comprises the following steps:
(i) charging first predetermined amounts of at least one surface active agent and water in a reactor followed by heating the reactor at a first predetermined temperature to obtain a first solution;
(ii) adding a predetermined amount of an initiator to the first solution in the reactor at the first predetermined temperature under stirring to obtain a second solution;
(iii) gradually adding first predetermined amounts of at least one acrylic monomer and an acid to the second solution under stirring over a first predetermined time period followed by reacting at a second predetermined temperature for a second predetermined time period to obtain a third solution;
(iv) separately, mixing second predetermined amounts of at least one acrylic monomer, the acid, the surface active agent, water and a predetermined amount of at least one silane monomer under stirring to obtain a pre-emulsion;
(v) gradually adding the pre-emulsion to the third solution under stirring in the reactor over a third predetermined time period followed by reacting for a fourth predetermined time period to obtain a fourth solution;
(vi) cooling the fourth solution in the reactor to a temperature in the range of 50 ºC to 70 °C followed by adding a predetermined amount of at least one chaser catalyst to the fourth solution under stirring and continuing stirring for a fifth predetermined time period to obtain a fifth solution; and
(vii) cooling the fifth solution in the reactor to a temperature in the range of 30 ºC to 50 °C followed by adding a predetermined amount of at least one additive under stirring and continuing stirring for a sixth predetermined time period to obtain the acrylic silicone emulsion.
The process for the preparation of the acrylic silicone emulsion is described in detail herein below.
Step (i): First predetermined amounts of a surface active agent and water are charged in a reactor (emulsion reactor) followed by heating the reactor at a first predetermined temperature to obtain a first solution.
In accordance with an embodiment of the present disclosure, the reactor is fitted with reflux condenser, stirrer, dropping pump and thermocouple.
In an embodiment of the present disclosure, the surface active agent can be selected from the group consisting of succinic acid ester based sodium sulfonate, sodium alkyl allyl sulfosuccinate and adipic acid ester based sodium sulfonates. In an exemplary embodiment of the present disclosure, the surface active agent is sodium alkyl allyl sulfosuccinate.
In an embodiment of the present disclosure, the first predetermined amount of the surface active agent is in the range of 0.5 mass% to 1.0 mass% with respect to the total mass of the emulsion. In an exemplary embodiment of the present disclosure, the first predetermined amount of the surface active agent is 0.6 mass% with respect to the total mass of the emulsion.
The concentration of the surface active agent is in the range of 20% to 60 %. In an exemplary embodiment of the present disclosure, the concentration of the surface active agent is 40%.
In an embodiment of the present disclosure, water is demineralized water.
In an embodiment of the present disclosure, the first predetermined amount of water is in the range of 20 mass% to 35 mass% with respect to the total mass of the emulsion. In an exemplary embodiment of the present disclosure, the amount of water is 24 mass% with respect to the total mass of the emulsion.
In accordance with an embodiment of the present disclosure, the first predetermined temperature is in the range of 60 °C to 100 °C. In an exemplary embodiment of the present disclosure, the first predetermined temperature is 80 ºC.
Step (ii): A predetermined amount of an initiator is added to the first solution (obtained in step (i)) in the reactor at the first predetermined temperature under stirring to obtain a second solution.
In accordance with the embodiment of the present disclosure, the initiator (polymerization initiator) can be selected from the group consisting of ammonium persulfate, potassium persulfate and azobisisobutyronitrile (AIBN). In an exemplary embodiment of the present disclosure, the initiator is ammonium persulfate.
Any initiator catalyst has a particular half-life up to which it is in workable condition. The initiator catalyst used in an exemplary embodiment of the present disclosure is ammonium persulfate which activates and works at a temperature range of 78 °C to 82 °C only. Therefore, while adding the initiator, the temperature of the reactor is maintained in the range of 60 °C to 100 °C.
In an embodiment of the present disclosure, the predetermined amount of the initiator is in the range of 0.01 mass% to 0.2 mass%. In an exemplary embodiment of the present disclosure, the predetermined amount of the initiator is 0.12 mass% with respect to the total mass of the emulsion.
Step (iii): First predetermined amounts of at least one acrylic monomer and an acid are added gradually to the second solution (obtained in step (ii)) in the reactor over a first predetermined time period followed by reacting at a second predetermined temperature at a second predetermined time period to obtain a third solution.
In accordance with the embodiment of the present disclosure, the acrylic monomer can be at least one selected from the group consisting of methyl methacrylate, n-butyl acrylate, n-butyl methacrylate, lauryl methacrylate, stearyl methacrylate and 2-ethyl hexyl acrylate. In accordance with an exemplary embodiment of the present disclosure, the acrylic monomers are methyl methacrylate, butyl acrylate. In accordance with another exemplary embodiment of the present disclosure, the acrylic monomers are methyl methacrylate, butyl acrylate and lauryl methacrylate. In yet another exemplary embodiment of the present disclosure, the acrylic monomers are methacrylate, butyl acrylate and stearyl methacrylate.
In an embodiment of the present disclosure, the first predetermined amount of the acrylic monomers is in the range of 5 mass% to 10 mass% with respect to the total mass of the emulsion. In an exemplary embodiment of the present disclosure, the first predetermined amount of the acrylic monomers is 7 mass% with respect to the total mass of the emulsion.
In accordance with the embodiment of the present disclosure, the acid is acrylic acid, preferably, methacrylic acid.
In an embodiment of the present disclosure, the first predetermined amount of the acid is in the range of 0.05 mass% to 0.5 mass%. In an exemplary embodiment of the present disclosure, the first predetermined amount of the acid is 0.1 mass% with respect to the total mass of the emulsion. In another exemplary embodiment of the present disclosure, the first predetermined amount of the acid is 0.3 mass% with respect to the total mass of the emulsion. In yet another exemplary embodiment of the present disclosure, the first predetermined amount of the acid is 0.4 mass% with respect to the total mass of the emulsion.
In an embodiment of the present disclosure, the first predetermined time period is in the range of 20 minutes to 40 minutes. In an exemplary embodiment of the present disclosure, the first predetermined time period is 30 minutes.
In an embodiment of the present disclosure, the second predetermined time period is in the range of 40 minutes to 90 minutes. In an exemplary embodiment of the present disclosure, the first predetermined time period is 60 minutes.
In an embodiment of the present disclosure, the second predetermined temperature is in the range of 60 °C to 100 ºC. In an exemplary embodiment of the present disclosure, the first predetermined temperature is 80 ºC.
Step (iv): Separately, second predetermined amounts of at least one acrylic monomer, the acid, the surface active agent, water and a predetermined amount of at least one silane monomer are mixed under stirring to obtain a pre-emulsion.
In an embodiment of the present disclosure, the second predetermined amount of the acrylic monomers is in the range of 25 mass% to 40 mass% with respect to the total mass of the emulsion. In an exemplary embodiment of the present disclosure, the second predetermined amount of the acrylic monomers is 31 mass% with respect to the total mass of the emulsion.
In an embodiment of the present disclosure, the second predetermined amount of the acid is in the range of 0.05 mass% to 0.5 mass%. In an exemplary embodiment of the present disclosure, the second predetermined amount of the acid is 0.2 mass% with respect to the total mass of the emulsion. In another exemplary embodiment of the present disclosure, the second predetermined amount of the acid is 0.4 mass% with respect to the total mass of the emulsion. In yet another exemplary embodiment of the present disclosure, the second predetermined amount of the acid is 0.3 mass% with respect to the total mass of the emulsion.
In an embodiment of the present disclosure, the second predetermined amount of the surface active agent is in the range of 0.5 mass% to 1.0 mass% with respect to the total mass of the emulsion. In an exemplary embodiment of the present disclosure, the second predetermined amount of the surface active agent is 0.6 mass% with respect to the total mass of the emulsion.
In accordance with the present disclosure, the silane monomer can be at least one selected from the group consisting of methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, n-butyltrimethoxysilane, n-hexyltrimethoxysilane, n-octyltrimethoxysilane, n-decyltrimethoxysilane, n-dodecyltrimethoxysilane, hexadecyltrimethoxysilane, octadecyltrimethoxysilane, 3-acryloxy-1-propyltrimethoxysilane and 3-methacryloxy-1-propyltrimethoxy silane.
In an embodiment of the present disclosure, the predetermined amount of the silane monomer is in the range of 2 mass% to 10 mass% with respect to the total mass of the emulsion. In an exemplary embodiment of the present disclosure, the predetermined amount of the silane monomer is 4.2 mass% with respect to the total mass of the emulsion. In another exemplary embodiment of the present disclosure, the predetermined amount of the silane monomer is 2.2 mass% with respect to the total mass of the emulsion. In yet another exemplary embodiment of the present disclosure, the predetermined amount of the silane monomer is 3.2 mass% with respect to the total mass of the emulsion.
The conventional methods for preparing acrylic silicone emulsions involves separate addition of silane monomers which leads to the formation of unreacted silicone oligomers with oily layer on the top layer of the emulsion i.e. there is no 100 % conversion and incomplete grafting of silicone in the acrylic back-bone. However, in the present disclosure, the higher content of silane monomers are stabilized in the pre-emulsion with optimized dosage of surfactant micelles which provides 100 % conversion and grafting of silicone in the acrylic back-bone.
The addition of the surface active agents in water followed by addition of the initiator are done separately in accordance with the process of the present disclosure so as to create micelles where seed monomer can polymerized first followed by adding pre-emulsion for further polymerization.
Step (v): The pre-emulsion (obtained in step (iv)) is added gradually to the third solution (obtained in step (iii)) in the reactor over a third predetermined time period followed by reacting for a fourth predetermined time period to obtain a fourth solution.
In accordance with an embodiment of the present disclosure, the third predetermined time period is in the range of 3 hours to 6 hours. In an exemplary embodiment of the present disclosure, the third predetermined time period is 4.5 hours.
Graduall addition i.e. the flow rate per minute should be such that the total amount of emulsion addition should complete in 4.5 hours as the initiator used in an exemplary embodiment is ammonium persulphate which has a half-life of 5 hours at 80 °C. Therefore, the addition of the pre-emulsion should be completed before 5 hours as after 5 hours the initiator may get inactivated which in turn would lead to unreacted free monomers in the reaction mixture.
In an embodiment of the present disclosure, the fourth predetermined time period is in the range of 30 minutes to 90 minutes. In an exemplary embodiment of the present disclosure, the fourth predetermined time period is 60 minutes.
Step (vi): The fourth solution (obtained in step (vi)) in the reactor is cooled a temperature in the range of 50 ºC to 70 °C followed by adding a predetermined amount of at least one chaser catalyst to the fourth solution under stirring and continuing for a fifth time period to obtain a fifth solution.
In an exemplary embodiment of the present disclosure, the temperature is 60 °C.
In an embodiment of the present disclosure, the chaser catalyst is at least one selected from the group consisting of tertiary butyl hydroperoxide, sodium formaldehyde sulphoxalate, sodium metabisulphate, hydrogen peroxide and tartaric acid. In an exemplary embodiment of the present disclosure, the chaser catalysts are tertiary butyl hydroperoxide and sodium formaldehyde sulphoxalate.
In an embodiment of the present disclosure, the amount of the chaser catalyst is in the range of 0.01 mass% to 0.2 mass% with respect to the total mass of the emulsion. In an exemplary embodiment of the present disclosure, the amount of the chaser catalyst is 0.1 with respect to the total mass of the emulsion.
In an embodiment of the present disclosure, the fifth predetermined time period is in the range of 40 minutes to 80 minutes. In an exemplary embodiment of the present disclosure, the fifth predetermined time period is 60 minutes.
Step (vii): The fifth solution in the reactor is cooled to a temperature in the range of 30 ºC to 50 °C followed by adding predetermined amount of at least one additive under stirring and continuing stirring for a sixth predetermined time period to obtain the acrylic silicone emulsion.
In accordance with the present disclosure, the at least one additive can be selected from pH adjusting agent, defoaming agent and biocide.
The pH adjusting agent can be selected from the group consisting of liquor ammonia, sodium hydroxide and potassium hydroxide. In an exemplary embodiment of the present disclosure, the pH adjusting agent is liquor ammonia.
The defoaming agent can be selected from the group consisting of polyether siloxane based defoamer, polyester siloxane based defoamer and long chain fatty acid silicone modified defoamer. In an exemplary embodiment of the present disclosure, the defoaming agent is polyether siloxane based defoamer.
The biocide can be selected from the group consisting of 1,2-benzisothiazolin-3-one, methylisothiazolinone, methylchloro-isothiazolinone, octylisothiazolinone, dicholoro-octylisothiazolinone, chloromethyl isothiazolinone and butyl benzisothiazolinone. In an exemplary embodiment of the present disclosure, the biocide is 1,2-benzisothiazolin-3-one, methylisothiazolinone.
The predetermined amount of the additive is in the range of 0.1 mass% to 2 mass% with respect to the total mass of the emulsion. In an exemplary embodiment of the present disclosure, the amount of the pH adjusting agent is 1.0 mass% with respect to the total mass of the emulsion. In an exemplary embodiment of the present disclosure, the amount of the defoaming agent is 0.1 mass% with respect to the total mass of the emulsion. In an exemplary embodiment of the present disclosure, the amount of the biocide is 0.2 mass% with respect to the total mass of the emulsion.
In an embodiment of the present disclosure, the sixth predetermined time period is in the range of 10 minutes to 30 minutes. In an exemplary embodiment of the present disclosure, the sixth predetermined time period is 15 minutes.
In accordance with an embodiment of the present disclosure, the obtained acrylic silicone emulsion is filtered by using a wire net having a predetermined mesh size in the range of 60 mesh to 100 mesh to obtain a solid mass. The solid mass is in the range of 41% to 44%. In an exemplary embodiment of the present disclosure, the solid mass is 43.5%. In another exemplary embodiment of the present disclosure, the solid mass is 41.5%.
In yet another aspect, the present disclosure provides a coating composition comprising an acrylic silicone emulsion.
In an embodiment of the present disclosure, the coating composition comprises the acrylic silicone emulsion.
In another embodiment of the present disclosure, the coating composition comprises a blend of the acrylic silicone emulsion and an elastomeric emulsion.
The elastomeric emulsion can be any conventional elastomeric emulsion having a thick and strong consistency and cures into a durable and highly elastic membrane when it dries.
In yet another embodiment of the present disclosure, the coating composition comprises a blend of the acrylic silicone emulsion and an elastomeric emulsion along with adhesion promoting additives, wherein the adhesion promoting additives are selected from silanes, siloxane derivatives, low molecular weight polyurethane derivatives and long chain fatty acid derivatives.
In an embodiment of the present disclosure, the acrylic silicone emulsion of the present disclosure is blended with an elastomeric emulsion in a weight ratio in the range of 10:90 to 90:10.
In accordance with the present disclosure, the acrylic silicone emulsion has a huge commercial applications such as in water based decorative and industrial paints; and coatings and adhesives. The acrylic silicone emulsion can be used in varnishes, stone coatings, interior and high weatherability exterior wall coatings, and adhesives and sealants such as liquid emulsion adhesives, hot-melt adhesives, flame retardant adhesives, pressure sensitive adhesives and the like.
The acrylic silicone emulsion of present disclosure can be used in the coating for anti-cracking, anti-peeling, high UV resistance (no yellowing), high scrub resistance, excellent water resistance, high dirt-pickup resistance (DPUR), high elongation and excellent crack-bridging ability (CBA).
The present disclosure provides the acrylic silicone emulsion that requires lower processing time and has stabilization of higher quantity of silane monomers in the pre-emulsion with optimum level of surfactant dosage.
Acrylic silicone emulsion of present disclosure is prepared in a controlled way with optimum cross-linking density by controlling the factors such as
• by using the optimized quantity of silane, stabilized in the pre-emulsion,
• by using optimized dosage of reactive surfactant,
• by using an optimized ratio of the acrylic monomer to the silane monomer,
• by optimizing the acid content,
• by optimizing process time, and
• by converting 100 % conversion of silane monomer to silicone polymer.
The acrylic silicone emulsion of the present disclosure either alone or in combination with other emulsions provides high dirt-pickup resistance (DPUR) along with high elongation and hence high crack-bridging ability (CBA).
The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment but are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.
The present disclosure is further described in light of the following experiments which are set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure. The following experiments can be scaled up to industrial/commercial scale and the results obtained can be extrapolated to industrial scale.
EXPERIMENTAL DETAILS
Experiment 1: Process for the preparation of the acrylic silicone emulsion in accordance with the present disclosure
Example 1: Preparation of an acrylic silicone emulsion
0.6 parts of 40% aqueous solution of sodium alkyl allyl sulfosuccinate (a co-polymerizable emulsifier/surfactant), 24 parts demineralized water were charged in a emulsion reactor fitted with reflux condenser, stirrer, dropping pump and thermocouple, followed by heating the emulsion reactor and heated the reactor to 80 °C to obtain a first solution.
0.04 parts of ammonium persulfate solution (polymerization initiator) was added to the first solution in the reactor at 80 °C to obtain a second solution.
4 parts methyl methacrylate (acrylic monomer), 3 parts n-butyl acrylate (acrylic monomer) and 0.1 parts methacrylic acid (acid) were added gradually to the second solution under stirring over 30 minutes, followed by reacting at 80 °C for 1 hour to obtain a third solution.
Separately, 16 parts methyl methacrylate (acrylic monomer), 15 parts n-butyl acrylate (acrylic monomer) and 0.2 parts methacrylic acid (acid), 0.2 parts ?-methacryl oxypropyltrimethoxysilane (silane monomer), 4 parts dimethyl dimethoxysilane (silane monomer), 0.6 part of 40% aqueous solution of sodium alkyl allyl sulfosuccinate (surfactant) and 29 parts demineralized water were mixed under stirring to obtain a pre-emulsion.
The obtained pre-emulsion was added gradually to the third solution under stirring in the reactor over 4.5 hours followed by reacting for 1 hour to obtain a fourth solution.
The obtained fourth solution in the reactor was cooled to 60 °C, followed by adding 0.05 parts of tertiary butyl hydroperoxide (chaser catalyst) and 0.05 parts of sodium formaldehyde sulphoxalate (chaser catalyst) to the fourth solution under stirring and continued stirring for 60 minutes to obtain a fifth solution.
The fifth solution in the emulsion reactor was cooled to 40 °C, followed by adding 1 mass% of liquor ammonia (pH adjusting agent), 0.1 mass% of polyether siloxane based defoamer (defoaming agent) and 0.2 mass% of 1,2-benzisothiazolin-3-one biocide) under stirring and continued stirring for 15 minutes to obtain the acrylic silicone emulsion (batch).
The so obtained batch was filtered through 80-mesh wire net and 43.5% solid mass was obtained. The pH of the emulsion was 9.
Examples 2-6: Preparation of an acrylic silicone emulsion
The same procedure of Example 1 was repeated by varying the components and their amounts as summarized in Table 1 to obtain the acrylic silicone emulsion.
Comparative examples:
Comparative examples 1-3: Preparation of acrylic silicone emulsion
The same procedure of Example 1 was repeated for the comparative examples 1 and 2 by varying the components and their amounts to obtain the acrylic silicone emulsion.
The predetermined amounts of the components used in all the examples 1-6 and the comparative examples 1-3 are summarized in Table 1 below.
Table 1: Components and amounts of components used in the preparation of acrylic silicone emulsion in accordance with the present disclosure
Sr. No. Components of acrylic silicone emulsion Ex ample 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Comparative Example 3
1 DM Water 56 55.3 55.8 55 55 56 54.3 54.5 54.7
2 Sodium alkyl allyl sulfosuccinate 1.20 1.20 1.20 1.20 1.20 1.20 1.20 1.20 1.20
3 Ammonium Persulphate 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12
4 Methyl Methacrylate 20 20 20 19 19 18 20 20 20
5 Butyl acrylate 18 18 18 18 18 20 18 18 18
6 Methacrylic Acid 0.3 0.3 0.3 0.3 0.3 0.3 0.8 0.6 0.3
7 Lauryl methacrylate 0.0 0.0 0.0 1.0 0.0 0.0 0.0 0.0 0.0
8 Stearyl methacrylate 0.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 0.0
9 Methacryloxypropyltrimethoxysilane 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2
10 Dimethyldimethoxysilane 4.0 3.5 3.0 4.0 4.0 4.0 4.0 4.0 4.0
11 Tertiary Butyl Hydroperoxide 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.0
12 Sodium Formaldehyde Sulphoxalate 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.0
13 Liquor Ammonia 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0
14 Defoamer 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1
15 Biocide 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2
Experiment 2: Preparation of coating composition
Example (a): Preparation of coating composition by using the acrylic silicone emulsion prepared in the example 1 of the present disclosure
10 mass% of the acrylic silicone emulsion prepared in Example 1 of Experiment 1 was mixed with 30 mass% of elastomeric emulsion under stirring (in a mass ratio of 1:3) along with 2 mass% of a surfactant, 0.5 mass% of a defoamer, 1 mass% of an adhesion promoter and 56.5 mass% of water to obtain a coating composition. The so obtained coating composition was further tested for its properties.
Example (b) to (i): Preparation of coating composition by using the acrylic silicone emulsion prepared in the examples 2-6 and the comparative examples 1-3 of the present disclosure
The same procedure of Example (a) was repeated except the acrylic silicone emulsions prepared in the examples 2-6 and the comparative examples 1-3 were used to obtain the coating composition of Examples (b) to (i) respectively.
Experiment 3: Effect of the acrylic silicone emulsion prepared in Examples 1-6 and comparative examples 1-3
The coating compositions of Examples (a) to (i) were prepared by using the acrylic silicone emulsions prepared in examples 1-6 and in comparative examples 1-3 respectively. The obtained coating compositions were analyzed for the coat/paint properties such as stability, compatibility with the acrylic silicone emulsion, compatibility in pigmented paint, crack bridging ability (in mm) in the paint and dirt pickup resistance in paint. The results of the analysis are summarized in Table 2.
Table 2: Properties of the coating compositions comprising acrylic silicone emulsion of the present disclosure
Properties Example (a) Example (b) Example (c) Example (d) Example (e) Example (f) Comparative example (g) Comparative example (h) Comparative example (i)
Stability and Compatibility with emulsion Yes Yes Yes Yes Yes Yes No No No
Compatibility in pigmented paint Yes Yes Yes Yes Yes Yes No No No
Crack Bridging ability (mm) in paint 0.7 No No 0.5 0.5 0.5 No No 0.6
Dirt pickup resistance in paint Yes No No Yes Yes No No No No
The results of Table 2 clearly indicated that the coating compositions prepared in examples (a) to (f) showed good stability and compatibility in paints, good compatibility in the pigmented paint. Further, it is observed that the coating compositions of the present disclosure prepared in examples (a) to (f) showed good crack bridging ability in paint along with good dirt pick up resistance.
TECHNICAL ADVANCEMENTS
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of;
? an acrylic silicone emulsion that can be used in a coating composition that;
• has high dirt-pickup resistance (DPUR);
• has high elongation;
• has excellent crack-bridging ability (CBA); and
• is economic; and
? a process for the preparation of an acrylic silicone emulsion that;
• is simple, economic, efficient and environmental friendly.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising, will be understood to imply the inclusion of a stated element, integer or step,” or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the invention to achieve one or more of the desired objects or results. While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Variations or modifications to the formulation of this invention, within the scope of the invention, may occur to those skilled in the art upon reviewing the disclosure herein. Such variations or modifications are well within the spirit of this invention.
The numerical values given for various physical parameters, dimensions and quantities are only approximate values and it is envisaged that the values higher than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the invention unless there is a statement in the specification to the contrary.
While considerable emphasis has been placed herein on the specific features of the preferred embodiment, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiment without departing from the principles of the disclosure. These and other changes in the preferred embodiment of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.
,CLAIMS:WE CLAIM:
1. An acrylic silicone emulsion, being a reaction product of:
a. at least one acrylic monomer;
b. at least one silane monomer;
c. an acid;
d. an initiator;
e. a surface active agent;
f. at least one chaser catalyst;
g. at least one additive; and
h. water.
2. The emulsion as claimed in claim 1 comprises:
a. 30 mass% to 50 mass% of said acrylic monomer;
b. 2 mass% to 10 mass % of said silane monomer;
c. 0.05 mass% to 1.0 mass% of said acid;
d. 0.01 mass% to 0.2 mass% of said initiator;
e. 0.5 mass% to 2 mass% of said surface active agent;
f. 0.01 mass% to 0.2 mass% of said chaser catalyst;
g. 0.1 mass% to 2 mass% of said additive; and
h. q.s. water,
wherein the mass% of each component is with respect to the total mass of said emulsion.
3. The emulsion as claimed in claim 1, wherein a mass ratio of said acrylic monomer to said silane monomer is in the range of 93:7 to 80:20.
4. The emulsion as claimed in claim 1, wherein said acrylic monomer is at least one selected from the group consisting of methyl methacrylate, n-butyl acrylate, n-butyl methacrylate, lauryl methacrylate, stearyl methacrylate and 2-ethyl hexyl acrylate.
5. The emulsion as claimed in claim 1, wherein said silane monomer is at least one selected from the group consisting of methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, n-butyltrimethoxysilane, n-hexyltrimethoxysilane, n-octyltrimethoxysilane, n-decyltrimethoxysilane, n-dodecyltrimethoxysilane, hexadecyltrimethoxysilane, octadecyltrimethoxysilane, 3-acryloxy-1-propyltrimethoxysilane and 3-methacryloxy-1-propyltrimethoxy silane.
6. The emulsion as claimed in claim 1, wherein said acid is an acrylic acid, preferably, methacrylic acid.
7. The emulsion as claimed in claim 1, wherein said initiator is selected from the group consisting of ammonium persulfate, potassium persulfate and azobisisobutyronitrile (AIBN).
8. The emulsion as claimed in claim 1, wherein said surface active agent is selected from the group consisting of succinic acid ester based sodium sulfonates, sodium alkyl allyl sulfosuccinate and adipic acid ester based sodium sulfonate.
9. The emulsion as claimed in claim 1, wherein said chaser catalyst is at least one selected from the group consisting of tertiary butyl hydroperoxide, sodium formaldehyde sulphoxalate, sodium metabisulphate, hydrogen peroxide and tartaric acid.
10. The emulsion as claimed in claim 1, wherein said additive is at least one selected from the group consisting of pH adjusting agent, defoaming agent and biocide.
11. The emulsion as claimed in claim 10, wherein
said pH adjusting agent is selected from the group consisting of liquor ammonia, sodium hydroxide and potassium hydroxide;
said defoaming agent is selected from the group consisting of polyether siloxane based defoamer, polyester siloxane based defoamer and long chain fatty acid silicone modified defoamer.
said biocide is selected from the group consisting of 1,2-benzisothiazolin-3-one, methylisothiazolinone, methylchloro-isothiazolinone, octylisothiazolinone, dicholoro-octylisothiazolinone, chloromethyl isothiazolinone and butyl benzisothiazolinone.
12. A process for the preparation of an acrylic silicone emulsion, said process comprising the following steps:
(i) charging first predetermined amounts of a surface active agent and water in a reactor followed by heating said reactor at a first predetermined temperature to obtain a first solution;
(ii) adding a predetermined amount of an initiator to said first solution in said reactor at said first predetermined temperature under stirring to obtain a second solution;
(iii) gradually adding first predetermined amounts of at least one acrylic monomer and an acid to said second solution under stirring over a first predetermined time period followed by reacting at a second predetermined temperature for a second predetermined time period to obtain a third solution;
(iv) separately, mixing second predetermined amounts of at least one acrylic monomer, said acid, said surface active agent, water and a predetermined amount of at least one silane monomer under stirring to obtain a pre-emulsion;
(v) gradually adding said pre-emulsion to said third solution under stirring in said reactor over a third predetermined time period followed by reacting for a fourth predetermined time period to obtain a fourth solution;
(vi) cooling said fourth solution in said reactor to a temperature in the range of 50 ºC to 70 °C followed by adding a predetermined amount of at least one chaser catalyst to said fourth solution under stirring and continuing stirring for a fifth predetermined time period to obtain a fifth solution; and
(vii) cooling said fifth solution in said reactor to a temperature in the range of 30 ºC to 50 °C followed by adding a predetermined amount of at least one additive under stirring and continuing stirring for a sixth predetermined time period to obtain said acrylic silicone emulsion.
13. The process as claimed in claim 12, wherein said surface active agent is at least one selected from the group consisting of succinic acid ester based sodium sulfonates, sodium alkyl allyl sulfosuccinate and adipic acid ester based sodium sulfonates.
14. The process as claimed in claim 12, wherein said initiator is selected from the group consisting of ammonium persulfate, potassium persulfate and azobisisobutyronitrile (AIBN).
15. The process as claimed in claim 12, wherein said acrylate monomer is at least one selected from the group consisting of methyl methacrylate, n-butyl acrylate, n-butyl methacrylate, lauryl methacrylate, stearyl methacrylate and 2-ethyl hexyl acrylate.
16. The process as claimed in claim 12, wherein said acid is acrylic acid, preferably, methacrylic acid.
17. The process as claimed in claim 12, wherein said silane monomer is at least one selected from the group consisting of methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, n-butyltrimethoxysilane, n-hexyltrimethoxysilane, n-octyltrimethoxysilane, n-decyltrimethoxysilane, n-dodecyltrimethoxysilane, hexadecyltrimethoxysilane, octadecyltrimethoxysilane, 3-acryloxy-1-propyltrimethoxysilane and 3-methacryloxy-1-propyltrimethoxy silane.
18. The process as claimed in claim 12, wherein said chaser catalyst is at least one selected from the group consisting of tertiary butyl hydroperoxide, sodium formaldehyde sulphoxalate, sodium metabisulphate, hydrogen peroxide and tartaric acid.
19. The process as claimed in claim 12, wherein said additive is at least one selected from the group consisting of a pH adjusting agent, a defoaming agent and a biocide
20. The process as claimed in claim 19, wherein said pH adjusting agent is selected from the group consisting of liquor ammonia, sodium hydroxide and potassium hydroxide.
21. The process as claimed in claim 19, wherein said defoaming agent is selected from the group consisting of polyether siloxane based defoamer, polyester siloxane based defoamer and long chain fatty acid silicone modified defoamer.
22. The process as claimed in claim 19, wherein said biocide is selected from the group consisting of 1,2-benzisothiazolin-3-one, methylisothiazolinone, methylchloro-isothiazolinone, octylisothiazolinone, dicholoro-octylisothiazolinone, chloromethyl isothiazolinone and butyl benzisothiazolinone.
23. The process as claimed in claim 12, wherein
• said first and second predetermined amounts of said surface active agent are independently in the range of 0.5 mass% to 1 mass%;
• said predetermined amount of said initiator is in the range of 0.05 mass% to 0.2 mass%;
• said first predetermined amount of said acrylic monomer is in the range of 5 mass% to 10 mass%;
• said second predetermined amount of said acrylic monomer is in the range of 25 mass% to 40 mass%;
• said first and second predetermined amounts of said acid are independently in the range of 0.05 mass% to 0.5 mass%;
• said predetermined amount of said silane monomer is in the range of 2 mass% to 10 mass%;
• said predetermined amount of said chaser catalyst is in the range of 0.01 mass% to 0.2 mass%;
• said predetermined amount of said additive is in the range of 0.1 mass% to 2 mass%; and
• said first and second predetermined amounts of water are independently in the range of 20 mass% to 35 mass%.
24. The process as claimed in claim 12, wherein said first and said second predetermined temperatures are independently in the range of 60 °C to 100 ºC;
25. The process as claimed in claim 12, wherein
• said first predetermined time period is in the range of 20 minutes to 40 minutes;
• said second predetermined time period is in the range of 40 minutes to 90 minutes;
• said third predetermined time period is in the range of 3 hours to 6 hours;
• said fourth predetermined time period is in the range of 30 minutes to 90 minutes;
• said fifth predetermined time period is in the range of 40 minutes to 80 minutes; and
• said sixth predetermined time period is in the range of 10 minutes to 30 minutes.
26. A coating composition comprising said acrylic silicone emulsion as claimed in claim 1 and an elastomeric emulsion in a mass ratio in the range of 10:90 to 90:10.

Dated this 28th day of November, 2022

_______________________________
MOHAN RAJKUMAR DEWAN, IN/PA – 25
of R.K. DEWAN & CO.
Authorized Agent of Applicant

TO,
THE CONTROLLER OF PATENTS
THE PATENT OFFICE, AT MUMBAI