DESC:FIELD OF THE INVENTION

[001] The present invention relates to the field of polymers, particularly to an epoxy resin composition.

BACKGROUND OF THE INVENTION

[002] Process equipment, such as pipelines and storage vessels, is predominantly used for transporting and storing water and food products consumed by human beings. The process equipment can be made up of a material such as copper, aluminum, cast iron, carbon steel, stainless steel, and alloys thereof. The process equipment is prone to corrosion problems, due to different factors like the use of toxic chemicals in the process equipment and climatic conditions (for example – humidity) at the site.

[003] Corrosion, particularly, deteriorates the material of the process equipment. Due to this, there is a need to replace the process equipment with new process equipment. This results in increasing undesired maintenance costs, which in turn increases the capital expenditure (CAPEX) of the entire process. In order to avoid any undesired maintenance costs, the use of coatings is significantly increasing to protect the process equipment from corrosion problems.

[004] It is well known in the art that epoxy based materials exhibit excellent properties including mechanical, thermal insulation and electrical insulation, resistance to chemical and heat and excellent adhesion. It is used for a wide range of applications such as coatings, paints, adhesives and composite materials. The use of epoxy resin has increased tremendously for coating purposes, particularly for coating the internal surface of the equipment predominantly used for transporting and storing products consumed by human beings. Particularly, for coating the internal surface of water pipelines, water storage vessels, and food products storage vessels.

[005] For such applications, i.e., for internal surface coating, the thickness of the coating is approximately in the range of 200 microns to 600 microns. The cost of epoxy resin has increased due to limited availability of the raw materials for preparing epoxy resin and increase in the use of epoxy resin. This in turn increases the entire cost (capital expenditure (CAPEX)) involved in coating the inner surface of the process equipment. There is, therefore, felt a need for an alternative to reduce the cost involved in coating the inner surface of the process equipment.

[006] This can be done by controlling the amount of epoxy resin to be used for coating the internal surface, which in turn facilitates in reducing the CAPEX. This is because, the CAPEX is dependent on the cost incurred due to the amount of epoxy resin used for coating the internal surface of the process equipment. The amount of epoxy resin to be used should be controlled in such a way that viscosity and flowability of epoxy resin remain unaffected.

[007] Conventionally, the amount of epoxy resin to be used for coating is controlled or reduced by mixing or diluting epoxy resin with solvents. This enables in reducing the CAPEX for coating the surface of the process equipment. However, solvents are responsible for corrosion and microbial contamination, which in turn deteriorates the quality of water passed through pipelines and food products stored in storage vessels and affects people’s health. The use of solvents with epoxy resin for coating of the internal surface of the water pipelines, water tanks, and food products storage vessels is not desired.

[008] It is well known in the art that the initial viscosity of epoxy resin is high. Therefore, to reduce the viscosity of epoxy resin for ease of application, it is imperative to heat epoxy resin approximately at a temperature in the range of 60 °C to 70 °C till a desired range of viscosity thereof is attained, before coating the internal surface of the process equipment. Heating requirement further increases the entire cost required for internal surface coating, thereby making the conventional process capital intensive.

[009] The present invention, therefore, provides an alternate composition to obviate the above-mentioned drawbacks.

DETAILED DESCRIPTION

[0010] In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without these specific details.

[0011] As used herein, the terms ‘a’, ‘an’, and ‘at least’ do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.

[0012] Reference herein to “one embodiment” or “another embodiment” means that a feature, structure, or characteristic described in accordance with the embodiment can be included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.

[0013] In the present context, unless and otherwise stated, the following terms should have the meaning as set forth below.
Sagging – it is the tendency of a wet coating to flow downward due to the gravity.
Sag resistance – it is the property of the coating to resist sagging when applied on slanted or vertical surfaces of process equipment.
Rheology – it is related to the deformation and flow of solids/liquids.

[0014] In the present context or following description, coating refers to a food grade epoxy resin composition.

[0015] As described herein above, solvents are conventionally used for controlling the amount of epoxy resin without affecting its viscosity and flowability. However, for coating the internal surface of the process equipment, solvent based coatings are not desired. Additionally, to reduce the viscosity of epoxy resin for ease of application, heating the epoxy resin is imperative, thereby resulting in increasing the overall cost involved in coating the internal surface of the process equipment. The present invention, therefore, envisages an epoxy resin composition that obviates the above-mentioned drawbacks.

[0016] The composition of the present invention comprises a first component and a second component. The first component and the second component are mixed in a pre-determined volume ratio. The pre-determined volume ratio of the first component to the second component can be 3:1.

[0017] The first component includes epoxy resin, a diluent, a deaerator, a wetting agent, a thixotropic agent, a pigment component and a filler component.

[0018] In accordance with one embodiment of the present disclosure, the amount of epoxy resin is in the range of 20 to 40% by weight of the first component. In accordance with still another embodiment of the present disclosure, the amount of epoxy resin is up to 25 % by weight of the first component.

[0019] The diluent can be one of a reactive diluent and a non-reactive diluent. The reactive diluent is divided into three groups, viz., aliphatic, aromatic and cycloaliphatic. In the present invention, the reactive diluent used can be a mono-functional aromatic reactive diluent based on cashew nut shell liquid.

[0020] It is a reactive diluent (a monofunctional epoxy resin diluent based on cashew nut shell liquid) that is being used in the said formulation. The purpose is to decrease the viscosity of the system and also increasing the liquid content in the system. Moreover, since it is a reactive diluent, it has epoxy functional groups, those can take part in final curing reaction. This means, this additive also controls the functionality (in terms of epoxy equivalent weight) of the resin. The presence of long fifteen carbon atom chain imparts flexibility to the coating.

[0021] The reactive diluent can be selected from the group consisting of C8 to C10 alkyl glycidyl ether, C12 to C14 alkyl glycidyl ether, phenyl glycidyl ether, glycidyl ether of cashew nut shell liquid, cresyl glycidyl ether, diglycidyl ether of C2 to C6 alkane diol, neopentyl glycol diglycidyl ether, cyclohexane dimethanol diglycidyl ether, and C2 to C4 alkane trimethylol triglycidyl ether.

[0022] In accordance with one embodiment of the present disclosure, the viscosity of the reactive diluent at 25 °C is 3 centipoise (cP) to 250 centipoise (cP). In accordance with another embodiment of the present disclosure, the viscosity of the reactive diluent is 10 cP to 120 cP. In accordance with still another embodiment of the present disclosure, the viscosity of the reactive diluent is 35 cP to 75 cP.

[0023] In accordance with one embodiment of the present disclosure, an epoxy equivalent weight of diluent is in the range of 145 to 600 g/eq. In accordance with another embodiment of the present disclosure, an epoxy equivalent weight of diluent is in the range of 250 to 580 g/eq. In accordance with still another embodiment of the present disclosure, an epoxy equivalent weight of diluent is in the range of 425 to 550 g/eq.

[0024] In accordance with one embodiment of the present disclosure, the amount of diluent is in the range of 7 to 15% by weight of the first component. In accordance with still another embodiment of the present disclosure, the amount of diluent is 10% by weight of the first component.

[0025] The diluent in the present invention is used for different purposes such as it facilitates in controlling the viscosity of the entire composition for ease of application, it can be used in final curing reaction since the diluent includes epoxy functional groups, it facilitates in enhancing flexibility of the coating, and the like.

[0026] The deaerator can be organic polymers or modified polysiloxanes comprising silicone. The modified polysiloxanes can be poly alkyl siloxanes or polyether alkyl siloxanes.

[0027] The absence of the deaerator in the composition results in foam formation. Due to the formation of foam, it can be difficult to identify whether the internal surface of the process equipment is coated appropriately and hence, foam formation is not desired. Therefore, the deaerator or defoaming agent is essentially used in the present composition and it plays a crucial role to avoid foam formation. Particularly, the low surface tension property of the deaerator enables inhibition of foam and bubble formation at the time of producing coating and/or its application. More particularly, the deaerator facilitates in removing bubbles/micro-air inclusions from the coating. This results in destabilization of the foam, which is desired.

[0028] In accordance with one embodiment of the present disclosure, the amount of the deaerator is in the range of 0.2 to 0.6 % by weight of the first component. In accordance with still another embodiment of the present disclosure, the amount of deaerator is up to 0.4% by weight of the first component.

[0029] The wetting agent can be selected from the group consisting of sodium salt of polyphosphates, sodium salt of polyacrylates, potassium salt of polyphosphates, potassium salt of polyacrylates, ammonium salt of polyphosphates, ammonium salt of polyacrylates, salts of unsaturated polyamine amides, and salts of low-molecular acidic polyesters. The wetting agent facilitates in homogenization of the composition.

[0030] In accordance with one embodiment of the present disclosure, the amount of the wetting agent is in the range of 0.2 to 0.8% by weight of the first component. In accordance with still another embodiment of the present invention, the amount of wetting agent is up to 0.6% by weight of the first component.

[0031] The thixotropic agent can be selected from the group consisting of modified castor wax with polyamide, modified castor wax with epoxy resin and oxidized polyethylene wax. The thixotropic agent plays a vital role in providing sag resisting property to the coating.

[0032] In accordance with another embodiment of the present disclosure, the amount of thixotropic agent is in the range of 0.3 to 1% by weight of the first component. In accordance with still another embodiment of the present disclosure, the amount of thixotropic agent is up to 0.6% by weight of the first component.

[0033] The pigment can be selected from the group consisting of titanium oxide, iron oxide, and zinc phosphate. The pigment is used for imparting color to the coating.

[0034] In accordance with one embodiment of the present disclosure, the amount of the pigment component is in the range of 0.2 to 3% by weight of the first component. In one embodiment of the present disclosure, the pigment component includes a white pigment as 1.2% and a black pigment as 0.4% by weight of the first component.

[0035] The filler can be selected from the group consisting of aluminium silicate, barium sulfate, calcium carbonate, calcium sulfate, kaolin, silica, fumed silica, silicon carbide, wollastonite, and hydrated magnesium silicate. The filler facilitates in improving the strength of the coating; and controlling the density and rheology of the composition.

[0036] In accordance with one embodiment of the present disclosure, the amount of the filler component is in the range of 40 to 65% by weight of the first component. In one embodiment of the present invention, the filler component includes a Reinforcing filler as 0.8%, a Silica micro filler as 25%, a Hydrated magnesium silicate as 24% and a Barium sulfate mineral filler as 12% by weight of the first component.

[0037] The second component of the composition includes a hardener. The hardener can be phenalkamine, i.e., the Mannich reaction of cardanol, formaldehyde and amines or the Mannich reaction of cardanol, formaldehyde and polyamide/cycloaliphatic amines. The present hardener imparts different properties, such as improved flexibility, resistance to salt and water, pot life and surface tolerance, to the coating.

[0038] A spraying nozzle has been used to spray the liquid epoxy inside the pipe as per the required thickness. Before applying the epoxy paint, internal surface of the pipe is cleaned. Heating the epoxy resin is intended to reduce the viscosity thereof so that the epoxy resin, with ease, can be sprayed from a sprayer. Particularly, heating reduces a possibility of the epoxy resin getting stuck in the sprayer. In the present invention, heating is not required as the viscosity of epoxy resin is approximately in the range of 1800 cP to 2200 cP at 40 °C for ease of application. This facilitates the coating application at a temperature of 40 °C which is low as compared to that of conventional requirement of 60 °C. This reduces the amount of energy required for heating the epoxy resin, thereby reducing the entire cost involved in coating the internal surface of the process equipment. Moreover, the thixotropic agent in the present composition facilitates in regaining the viscosity of the epoxy resin after coating to obviate sagging. The composition of the present invention enables coating of a desired thickness on the internal surface of the process equipment can be applied without sagging. The hardener facilitates in enhancing the curing rate. Further, enhanced curing rate enables achieving a high level of crosslinking at a faster rate, which is desired to produce a stable coating. Furthermore, enhanced curing rate facilitates in protecting the coating from coating failures, i.e., it improves the application productivity. The coating can be applied to the internal surface of the process equipment by a brush/brushes or sprayers.

[0039] In accordance with one embodiment of the present invention, the viscosity of the hardener at 25 °C is in the range of 2000 cP to 50000 cP. In accordance with another embodiment of the present invention, the viscosity of the hardener at 25 °C is in the range of 10000 cP to 30000 cP. In accordance with still another embodiment of the present invention, the viscosity of the hardener at 25 °C is in the range of 12000 cP to 50000 cP.

[0040] The technical advantages of the composition are provided herein below:
• the composition is devoid of solvents;
• without using any solvents (without diluting epoxy resin); the amount of epoxy resin to be used in the composition can be controlled, this facilitates in reducing the entire cost involved in coating the internal surface of the process equipment;
• the composition enables ease of application 40 °C without sagging;
• the viscosity and rheology of the coating can be controlled without using any solvents; and
• with relatively less amount of epoxy resin and without using solvents, the coating with a thickness approximately in the range of 200 microns to 600 microns can be applied on the internal surface of the process equipment without sagging.

[0041] Although a particular exemplary embodiment of the invention has been disclosed in detail for illustrative purposes, it will be recognized to those skilled in the art that variations or modifications of the disclosed invention, including the rearrangement in the configurations of the parts, changes in steps and their sequences may be possible. Accordingly, the invention is intended to embrace all such alternatives, modifications and variations as may fall within the spirit and scope of the present invention.

[0042] The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in the light of the above teaching.
,CLAIMS:1. An epoxy resin composition, comprising a first component and a second component mixed in a volume ratio of 3:1.

2. The composition according to claim 2, wherein the first component comprises;
- an epoxy resin in a range of 20-40 % by weight of the first component;
- a diluent in a range of 7 - 15 % by weight of the first component;
- a deaerator in a range of 0.2-0.6 % by weight of the first component;
- a wetting agent in a range of 0.2-0.8 % by weight of the first component;
- a thixotropic agent in a range of 0.3- 1.0 % by weight of the first component;
- a pigment component in a range of 0.2- 2.0 % by weight of the first component; and
- a filler component in a range of 40- 65 % by weight of the first component.

3. The composition according to claim 1, wherein the second component is a hardener.

4. The composition according to claim 3, wherein the hardener is phenalkamine.

5. The composition according to claim 4, wherein the phenalkamine is a Mannich adduct of cardanol, formaldehyde & amine.

6. The composition according to claim 1, wherein the diluent is one from a group consisting of C8 to C10 alkyl glycidyl ether, C12 to C14 alkyl glycidyl ether, phenyl glycidyl ether, glycidyl ether of cashew nut shell liquid, cresyl glycidyl ether, diglycidyl ether of C2 to C6 alkane diol, neopentyl glycol diglycidyl ether, cyclohexane dimethanol diglycidyl ether, and C2 to C4 alkane trimethylol triglycidyl ether.

7. The composition according to claim 1, wherein the deaerator is one from a group consisting of organic polymers, modified polysiloxanes comprising silicone.

8. The composition according to claim 1, wherein the wetting agent is one from a group consisting of of sodium salt of polyphosphates, sodium salt of polyacrylates, potassium salt of polyphosphates, potassium salt of polyacrylates, ammonium salt of polyphosphates, ammonium salt of polyacrylates, salts of unsaturated polyamine amides and salts of low-molecular acidic polyesters.

9. The composition according to claim 1, wherein the thixotropic agent is one from a group consisting of modified castor wax with polyamide, modified castor wax with epoxy resin and oxidized polyethylene wax.

10. The composition according to claim 1, wherein the pigment component includes at least one pigment from a group consisting of titanium oxide, iron oxide, zinc phosphate or a combination therof.

11. The composition according to claim 1, wherein the filler component includes at least one filler from a group consisting of aluminum silicate, barium sulfate, calcium carbonate, calcium sulfate, kaolin, silica, fumed silica, silicon carbide, wollastonite, hydrated magnesium silicate or a combination thereof.

12. The composition according to claim 2, wherein the first component comprises;
- an epoxy resin as 25 % by weight of the first component;
- the diluent as 10 % by weight of the first component;
- the deaerator as 0.4 % by weight of the first component;
- the wetting agent as 0.6 % by weight of the first component;
- the thixotropic agent as 0.6 % by weight of the first component;
- the pigment component as 1.6 % by weight of the first component; and
- the filler component as 61.8 % by weight of the first component.

13. The composition according to claim 12, wherein the pigment component includes a white pigment as 1.2% and a black pigment as 0.4% by weight of the first component.

14. The composition according to claim 12, wherein the filler component includes a Reinforcing filler as 0.8%, a Silica micro filler as 25%, a Hydrated magnesium silicate as 24% and a Barium sulfate mineral filler as 12% by weight of the first component.

15. The epoxy resin composition according to claim 1 is adapted to be used as a coating applied to inner surface of pipelines and containers carrying food material.

16. The epoxy resin composition according to claim 1 is adapted to be applied as a coating at a temperature in a range of 35-40 degree Celsius.