Molecular sieve desiccant tablet
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- JAIN MANISH
- Filing Date
- 2024-05-14
- Publication Date
- 2026-04-22
AI Technical Summary
Existing desiccants in granular form suffer from dust spillage and contamination issues, require specific equipment for dehumidification, and lack mechanical stability without compromising moisture adsorption performance.
Molecular sieve desiccant tablets composed of 65-70% molecular sieve powder, 25-30% attapulgite clay, and 2.5-3% magnesium stearate, prepared through homogeneous mixing, drying, pressing, and heat treatment to achieve mechanical stability and efficient moisture adsorption at low relative humidity.
The tablets exhibit high mechanical strength, efficient moisture adsorption at low relative humidity, and eliminate the need for polymeric binders, ensuring effective moisture control without dust spillage or equipment dependency.
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Abstract
Description
[0001] “MOLECULAR SIEVE DESICCANT TABLET”
[0002] FIELD OF THE INVENTION:
[0003] The present invention relates to molecular sieve desiccant composition, and more specifically to mechanically stable molecular sieve desiccant tablets.
[0004] BACKGROUND OF THE INVENTION:
[0005] Desiccants play an important role in day-to-day life for removal of moisture from products and articles of food, nutraceutical and drug industry. Thus, desiccants help to prolong the shelflife and maintain the quality of the product by preventing the growth of microbes and fungus in it. Many desiccants are known in the market depending on the market segment including silica gel, activated alumina, activated charcoal, zeolite, calcium chloride, clay, and molecular sieve.
[0006] The desiccants available in the market are mostly in the form of granules, beads or pellets enclosed in pouches and canisters. The Chinese Utility model CN207894150U to Ni Shengwen describes a molecular sieve type dehumidifying dryer with granular molecular sieve desiccant stored in a dehumidifying barrel. The US patent application US2008207434A1 to Martinez Jim and others describes sorbent tablets having a sorbent and a binder, where the sorbent is chosen from silica gel, molecular sieve, activated carbon or clay, and the tablets are coated with a polymer.
[0007] Thus, the formation of a desiccant in a shaped form requires coating with a polymeric agent. The desiccants available is granular form have the disadvantage of dust spillage and subsequent contamination of the drugs and nutraceuticals, and require specific equipment for dehumidification. There is a need of a desiccant with homogenously mixed components without any physical blending, further shaped in a form that is mechanically stable without compromising the moisture adsorption performance. Further there is a need of strongly bonded tablets having becomes mechanical stability.
[0008] SUMMARY OF THE INVENTION:
[0009] The present invention discloses a molecular sieve desiccant tablet that adsorbs moisture at low relative humidity (RH) condition (<20% RH). The tablet has 65% to 70% of molecular sieve powder, 25% to 30% attapulgite clay, and 2.5% to 3% magnesium stearate.
[0010] The molecular sieve powder in the molecular sieve desiccant tablet is selected from molecular sieve 4A powder, molecular sieve 5A powder, or molecular sieve 13x powder.
[0011] The present invention further describes a process 100 of preparation of the molecular sieve desiccant tablet. It includes a first step 110 of homogenously mixing molecular sieve powder of definite particle size with attapulgite clay and magnesium stearate, in a laboratory blender. The second step 120 includes adding water to the mixture of step 110 with continuous stirring to obtain homogeneous slurry.
[0012] The third step 130 includes drying the slurry to obtain a semi dried mixture. In the fourth step 140 the dried mixture is pressed in tablet press at constant pressure to obtain tablets of specific dimension. The fifth step 150 includes heat treating the tablets to remove any remaining moisture and obtaining the tablets of maximum mechanical strength.
[0013] In accordance with the present invention, in the fourth step 140, the tablets are pressed at a constant pressure between 20 to 25 Kn. In the fifth step 150 of the process of the present invention, the tablets are heated to 550°C at the ramp rate of 40-200°C for 1 hr, then are held at 200°C for 30 mins. The tablets are then heated at a ramp rate of 200-550°C for 1 hr, and finally held at 550 °C for 30 mins.
[0014] The molecular sieve desiccant tablets of the present invention are capable of adsorbing moisture at low relative humidity (RH) conditions (<20% RH).
[0015] DESCRIPTION OF THE INVENTION:
[0016] References in the specification to "one embodiment" or "an embodiment" means that a particular feature, structure, characteristic, or function described in connection with the embodiment is 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.
[0017] References in the specification to “preferred embodiment” means that a particular feature, structure, characteristic, or function described in detail thereby omitting known constructions and functions for clear description of the present invention.
[0018] The foregoing description of specific embodiments of the present invention has been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed and obviously many modifications and variations are possible in light of the above teaching.
[0019] The present invention discloses molecular sieve desiccant tablets prepared from a molecular sieve desiccant composition, and a process for preparing a molecular sieve desiccant tablet. The present invention enables preparation of molecular sieve desiccant tablets without incorporating a polymer.
[0020] In accordance with the present invention, the molecular sieve desiccant tablet of the present invention includes the molecular sieve desiccant composition having
[0021] 1) 65% to 70% of molecular sieve powder,
[0022] 2) 25% to 30% attapulgite clay, and
[0023] 3) 2.5% to 3% magnesium stearate.
[0024] In accordance with a preferred embodiment, the molecular sieve desiccant tablet includes
[0025] 1) 70 gm molecular sieve powder,
[0026] 2) 30 gm attapulgite clay, and
[0027] 3) 3 gm magnesium ste aiate.
[0028] In this preferred embodiment, the molecular sieve powder is molecular sieve 4A powder having particle size between 100 to 200 mesh.
[0029] In accordance with the present invention, the molecular sieve powder is mixed with attapulgite clay and shaped in tablet of high mechanical strength. The tablets are devoid of any polymer and the binding performance is obtained through addition of attapulgite clay. Now, a preferred process 100 of preparation of the molecular sieve desiccant tablet in accordance with the present invention is disclosed. The process includes several steps described as follows.
[0030] In a first step 110, molecular sieve powder of definite particle size is mixed with attapulgite clay and magnesium stearate, homogeneously in a laboratory blender.
[0031] This is followed by a second step 120 wherein water is added to the above mixture of step 110 with continuous stirring to obtain homogeneous slurry. The third step 130 includes drying the slurry to obtain a semi dried mixture.
[0032] In a fourth step 140, the dried mixture is pressed in tablet press at predefined constant pressure to obtain tablets of predefined dimension. In the last step i.e., a fifth step 150, the tablets are heat treated to remove any remaining moisture and the tablets of maximum mechanical strength are obtained.
[0033] In the first step 110, the molecular sieve powder is molecular sieve 4A powder having particle size between 100 to 200 mesh. In the second step, about 300ml of water is added to the mixture of the first step. In the fourth step 140, the tablets are pressed at a constant pressure between 20 to 25 Kn. In the last step 150, the tablets are heated to 550°C at the ramp rate of 40-200°C for 1 hr, then held at 200°C for 30 mins, then heated at a ramp rate of 200-550°C for 1 hr, and finally held at 550 °C for 30 mins.
[0034] In accordance with the present invention, the molecular sieve desiccant tablets are prepared to adsorb moisture at low relative humidity (RH) conditions (<20% RH). The tablets are dried at 450°C before packing to remove any moisture content within the tablet. The final moisture content of 15% during the process of preparation of the tablets enables efficient tablet preparation, and removal of the moisture content on heating incorporates development of adsorption pores within the structure, that advantageously facilitates fast rate of adsorption.
[0035] In accordance with the present invention, various dimensions of tablets are prepared as per the preferred process 100 of the present invention. These dimensions include 9x5 mm, 11x5 mm, 12x5 mm and 16x5 mm. It is observed that there is no significant effect of increasing the diameter of the tablets towards moisture absorption performance of tablets. The specific percentage weight gain of the tablet is directly proportional to the quantity of tablet content under observation.
[0036] EXAMPLES:
[0037] Only a few examples and implementations are disclosed. Variations, modifications, and enhancements to the described examples and implementations and other implementations can be made based on what is disclosed.
[0038] Examples are set forth herein below and are illustrative of different amounts and types of reactants and reaction conditions that can be utilized in practicing the disclosure. It will be apparent, however, that the disclosure can be practiced with other amounts and types of reactants and reaction conditions than those used in the examples, and the resulting devices various different properties and uses in accordance with the disclosure above and as pointed out hereinafter. EXAMPLE 1: MOLECULAR SIEVE DESICCANT TABLET WITH
[0039] COMPOSITION IN UNIT QUANTITIES:
[0040] The molecular sieve desiccant tablet includes:
[0041] 1) 70 gm molecular sieve 4A powder having particle size between 100 to 200 mesh,
[0042] 2) 30 gm attapulgite clay, and
[0043] 3) 3 gm magnesium stearate.
[0044] The specification of the tablets is as follows:
[0045] Table 1: Specification of tablets
[0046] EXAMPLE 2: PROCESS OF PREPARING MOLECULAR SEIVE 4 A
[0047] DESICCANT TABLET:
[0048] The process for preparing the molecular sieve 4A desiccant tablet is described below:
[0049] 1) 70 g of powdered molecular sieve 4A having particle size between 100 to 200 mesh is mixed with 30 g of attapulgite clay and 3 g of magnesium stearate in a laboratory blender to obtain a molecular sieve mixture.
[0050] 2) 300 ml of distilled water is added to the above mixture under continuous stirring to obtain a homogeneous slurry. 3) This slurry is dried at 200°C for 90 minutes to obtain a semi dried mixture containing 15% moisture.
[0051] 4) The semi dried mixture is passed through 18 mesh sieves.
[0052] 5) The semi dried mixture is pressed in Tablet press with pressure of 20 Kn.
[0053] 6) The as prepared tablets are further heated to 550°C with the ramp rate of 40- 200°C for 1 hr, the held at 200°C for 30 mins, followed by heating at ramp rate of 200-550°C for 1 hr, and finally held at 550 °C for 30 mins.
[0054] EXAMPLE 3: PROCESS OF PREPARING MOLECULAR SEIVE 5 A DESICCANT TABLET:
[0055] The process for preparing the molecular sieve 5A desiccant tablet is described below:
[0056] 1) 72 g of powdered molecular sieve 5A having particle size between 100-200 mesh, is mixed with 27 g of attapulgite clay and 2.6 g of magnesium stearate in a laboratory blender to obtain a molecular sieve mixture .
[0057] 2) 300 ml of distilled water is added to the above mixture under continuous stirring to obtain a homogeneous slurry.
[0058] 3) This slurry is dried at 200°C for 90 minutes to obtain a semi dried mixture containing 15% moisture.
[0059] 4) The semi dried mixture is passed through 18 mesh sieves.
[0060] 5) The semi dried mixture is pressed in Tablet press with pressure of 22 Kn. 6) The as prepared tablets are further heated to 550°C with the ramp rate of 40- 200°C for 1 hr, the held at 200°C for 30 mins, followed by heating at ramp rate of 200-550°C for 1 hr, and finally held at 550 °C for 30 mins.
[0061] EXAMPLE 4: PROCESS OF PREPARING MOLECULAR SEIVE 13x DESICCANT TABLET:
[0062] The process for preparing the molecular sieve 13x desiccant tablet is described below:
[0063] 1) 74 g of powdered molecular sieve 13x having particle size between 100-200 mesh, is mixed with 29 g of attapulgite clay and 2.9 g of magnesium stearate in a laboratory blender 74 g of powdered molecular sieve 13x is mixed with 29 g of attapulgite clay and 2.9 g of magnesium stearate in a laboratory blender.
[0064] 2) 300 ml of distilled water is added to the above mixture under continuous stirring to obtain a homogeneous slurry.
[0065] 3) This slurry is dried at 200°C for 90 minutes to obtain a semi dried mixture containing 15% moisture.
[0066] 4) The semi dried mixture is passed through 18 mesh sieves.
[0067] 5) The semi dried mixture is pressed in Tablet press with pressure of 25 Kn.
[0068] 6) The as prepared tablets are further heated to 550°C with the ramp rate of 40- 200°C for 1 hr, the held at 200°C for 30 mins, followed by heating at ramp rate of 200-550°C for 1 hr, and finally held at 550 °C for 30 mins. EXAMPLE 5: MOISTURE ADSORPTION CAPACITY OF MOLECULAR
[0069] SIEVE DESICCANT TABLET
[0070] Different dimensions (9 x 5 mm, 11 x 5 mm, 12 x 5 mm and 16 x 5 mm) of tablets were prepared to observe the effect of increasing diameter towards moisture adsorption capacity of the tablets. The end results suggested that not much difference in the moisture adsorption performance of the tablet composition is observed with respect to dimension of the tablet. The specific percentage weight gain in the tablets was directly proportional to the quantity of tablet content under observation and relative humidity.
[0071] These and other embodiments will be apparent to those of skill in the art and others in view of the following detailed description of some embodiments. It should be understood, however, that this summary, and the detailed description illustrate only some examples of various embodiments, and are not intended to be limiting to the invention as claimed.
[0072] Advantageously, the method of preparation of molecular sieve desiccant tablets in accordance with the present invention increases the life expectancy of the desiccant. The method provides homogenous blending of the constituents of the tablet before tablet formation. In this method, the ingredients being made into slurry and mixed in water ascertain homogeneous mixing of the constituents. The molecular sieve desiccant tablets adsorb moisture at low relative humidity (RH) conditions (<20% RH). Further, the partially moist mixture result into strongly bonded tablets, that further become mechanically stable after complete removal of moisture through drying. Thus, the present invention provides tablets of high mechanical strength without any coating substance and without compromising the moisture adsorption capacity of the tablets. The tablets prepared by the method of the present invention does not use any polymeric binder like PVA, PVP or EVA; as a result, it is possible to heat the tablets up to 550°C.
[0073] The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, to thereby enable others, skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated.
[0074] It is understood that various omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the scope of the present invention.
Claims
CLAIMS:
1. A molecular sieve desiccant tablet characterized to adsorb moisture at low relative humidity (RH) condition (<20% RH), such that the said tablet comprising: a) 65% to 70% of molecular sieve powder having particle size between 100 to 200 mesh; b) 25% to 30% attapulgite clay; and c) 2.5% to 3% magnesium stearate.
2. The molecular sieve desiccant tablet as claimed in Claim 1, wherein the molecular sieve powder being selected from molecular sieve 4A powder, molecular sieve 5 A powder, or molecular sieve 13x powder.
3. A process 100 of preparation of the molecular sieve desiccant tablet as claimed in Claim 1 including: a) a first step 110 of homogenously mixing molecular sieve powder of definite particle size with attapulgite clay and magnesium stearate, in a laboratory blender; b) a second step 120 of adding water to the mixture of step 110 with continuous stirring to obtain homogeneous slurry; c) a third step 130 of drying the slurry to obtain a semi dried mixture; d) a fourth step 140 of pressing the dried mixture in tablet press at constant pressure to obtain tablets of specific dimension; and e) a fifth step 150 of heat treating the tablets to remove any remaining moisture and obtaining the tablets of maximum mechanical strength.
4. The process 100 as claimed in Claim 3, wherein in the fourth step 140, the tablets being pressed at a constant pressure between 20 to 25 Kn.
5. The process 100 as claimed in Claim 3, wherein in the fifth step 150, the tablets being heated to 550°C at the ramp rate of 40-200°C for 1 hr, then being held at 200°C for 30 mins, then being heated at a ramp rate of 200- 550°C for 1 hr, and finally being held at 550 °C for 30 mins.
6. The molecular sieve desiccant tablets as claimed in Claim 1, wherein the tablets demonstrating moisture adsorption at low relative humidity (RH) conditions (<20% RH).