Molecular Sieve Desiccant Tablets

Abstract

This invention relates to molecular sieve desiccant tablets and a process for preparing molecular sieve desiccant tablets. The molecular sieve desiccant tablets contain 65% to 70% molecular sieve powder, 25% to 30% attapulgite clay, and 2.5% to 3% magnesium stearate. The tablets have diameters of 9 mm, 11 mm, 12 mm, and 16 mm, and a height of 5 mm. The molecular sieve desiccant tablets adsorb moisture under low relative humidity (RH) conditions (<20% RH). The process of this invention leads to achieving tablets with maximum mechanical strength. In this process, the components are made into a slurry and mixed in water, ensuring uniform mixing of the components.

Description

Technical Field

[0001] The present invention relates to a molecular sieve desiccant composition, and more specifically to a mechanically stable molecular sieve desiccant tablet.

Background Art

[0002] Desiccants play an important role in daily life for removing moisture from products and articles in the food, dietary supplement, and pharmaceutical industries. That is, desiccants help extend the shelf life and maintain the quality of products by preventing the growth of microorganisms and fungi in the products. Many desiccants, including silica gel, activated alumina, activated carbon, zeolites, calcium chloride, clay, and molecular sieves, are known in the market depending on the market segment.

[0003] Most desiccants available in the market are in the form of granules, beads, or pellets enclosed in pouches and canisters. The Chinese Utility Model Patent No. CN207894150U of Ni Shengwen describes a molecular sieve type dehumidifying dryer having granular molecular sieve desiccant stored in a dehumidifying barrel. The US Patent Application Publication No. 2008207434A1 of Martinez Jim et al. describes an adsorbent tablet having an adsorbent and a binder, the adsorbent being selected from silica gel, molecular sieve, activated carbon, or clay, and the tablet being coated with a polymer.

[0004] Therefore, the formation of a desiccant in a formed form requires coating with a polymeric agent. The available desiccants are in granular form and have the disadvantages of dust leakage and subsequent contamination of drugs and dietary supplements, and also require specific equipment for dehumidification. There is a need for a desiccant having components uniformly mixed without physical mixing and further formed in a mechanically stable form without impairing the moisture adsorption performance. Furthermore, there is a need for a firmly bound tablet having mechanical stability.

Summary of the Invention

[0005] The present invention discloses molecular sieve desiccant tablets that adsorb moisture under low relative humidity (RH) conditions (<20% RH). The tablets contain 65% to 70% molecular sieve powder, 25% to 30% attapulgite clay, and 2.5% to 3% magnesium stearate.

[0006] The molecular sieve powder in the molecular sieve desiccant tablets is selected from molecular sieve 4A powder, molecular sieve 5A powder, or molecular sieve 13x powder.

[0007] The present invention further describes a process 100 for the preparation of molecular sieve desiccant tablets. It comprises a first step 110 in which molecular sieve powder of a certain particle size is uniformly mixed with attapulgite clay and magnesium stearate in a laboratory blender. A second step 120 comprises adding water to the mixture from step 110 while continuously stirring to obtain a homogeneous slurry.

[0008] The third step 130 includes drying the slurry to obtain a semi-dried mixture. The fourth step 140 involves pressing the dried mixture in a tablet press at a constant pressure to obtain tablets of a specific size. The fifth step 150 includes heat-treating the tablets to remove residual moisture and obtain tablets with maximum mechanical strength.

[0009] According to the present invention, in the fourth step 140, the tablet is pressed with a constant pressure of 20Kn to 25Kn. In the fifth step 150 of the process of the present invention, the tablet is heated to 550°C for 1 hour at a ramp rate of 40 to 200°C, and then held at 200°C for 30 minutes. The tablet is then heated to 550°C for 1 hour at a ramp rate of 200 to 550°C, and finally held at 550°C for 30 minutes.

[0010] The molecular sieve desiccant tablets of the present invention can adsorb moisture under low relative humidity (RH) conditions (<20% RH). [Modes for carrying out the invention]

[0011] Detailed description of the invention: Any reference in this specification to “one embodiment” or “embodiment” means that certain features, structures, characteristics, or functions described in relation to an embodiment are included in at least one embodiment of the present invention. The phrase “in one embodiment” appearing in various parts of this specification does not necessarily refer to the same embodiment.

[0012] In this specification, references to “preferred embodiments” mean specific features, structures, properties, or functions that are described in detail, thereby omitting known configurations and functions for the sake of clarity in describing the invention.

[0013] The foregoing description relating to specific embodiments of the present invention is provided for illustrative and explanatory purposes only. They are not intended to be exhaustive or to limit the invention to the exact forms disclosed, and of course, many modifications and variations are possible in light of the teachings above.

[0014] This invention discloses molecular sieve desiccant tablets prepared from molecular sieve desiccant compositions, and a process for preparing molecular sieve desiccant tablets. This invention enables the preparation of molecular sieve desiccant tablets without incorporating polymers.

[0015] According to the present invention, the molecular sieve desiccant tablet of the present invention is 1) 65%~70% molecular sieve powder, 2) 25%~30% attapulgite clay, and 3) A molecular sieve desiccant composition comprising 2.5% to 3% magnesium stearate.

[0016] According to a preferred embodiment, the molecular sieve desiccant tablet is 1) 70 gm molecular sieve powder, 2) 30 gm of attapulgite clay, and 3) Contains 3 gm magnesium stearate.

[0017] In this preferred embodiment, the molecular sieve powder is molecular sieve 4A powder having a particle size between 100 and 200 mesh.

[0018] According to the present invention, molecular sieve powder is mixed with attapulgite clay and formed into tablets with high mechanical strength. The tablets contain no polymers, and the binding properties are obtained by the addition of attapulgite clay.

[0019] Herein, a preferred process 100 for preparing molecular sieve desiccant tablets according to the present invention is disclosed. This process includes several steps described below.

[0020] In the first step 110, molecular sieve powder of a consistent particle size is uniformly mixed with attapulgite clay and magnesium stearate in an experimental blender.

[0021] Following this, a second step 120 is performed in which water is continuously added to the mixture from step 110 while stirring to obtain a homogeneous slurry. A third step 130 includes drying the slurry to obtain a semi-dried mixture.

[0022] In the fourth step 140, the dried mixture is pressed in a tablet press at a predetermined constant pressure to obtain tablets of a predetermined size. In the final step, namely the fifth step 150, the tablets are heat-treated to remove any remaining moisture and obtain tablets with maximum mechanical strength.

[0023] In the first step 110, the molecular sieve powder is a molecular sieve 4A powder having a particle size between 100 and 200 mesh. In the second step, about 300 ml of water is added to the mixture of the first step. In the fourth step 140, the tablets are pressed at a constant pressure of 20 Kn to 25 Kn. In the last step 150, the tablets are heated to 550 °C at a ramp rate of 40 to 200 °C for 1 hour, then held at 200 °C for 30 minutes, then heated at a ramp rate of 200 to 550 °C for 1 hour, and finally held at 550 °C for 30 minutes.

[0024] According to the present invention, the molecular sieve desiccant tablets are prepared to adsorb moisture under low relative humidity (RH) conditions (<20% RH). After drying the tablets at 450 °C, they are packaged to remove the moisture content within the tablets. The final moisture content of 15% during the tablet preparation process enables efficient tablet preparation, and the removal of the moisture content during heating incorporates the development of adsorption pores within the structure, and advantageously increases the adsorption rate.

[0025] According to the present invention, tablets of various dimensions are prepared according to the preferred process 100 of the present invention. These dimensions include 9×5 mm, 11×5 mm, 12×5 mm, and 16×5 mm. It is observed that increasing the diameter of the tablets has no significant effect on the moisture absorption performance of the tablets. The specific percentage of the weight gain rate of the tablets is directly proportional to the amount of the tablet contents being observed.

[0026] Example: Only some examples and implementations are disclosed. Modifications, corrections, and enhancements to the described examples and implementations, as well as other implementations, can be made based on the disclosed content.

[0027] Examples are described below in this specification, but they are illustrative of different amounts and types of reactants and reaction conditions that can be used in practicing the present disclosure. However, the present disclosure can be practiced with amounts and types of reactants and reaction conditions other than those used in the examples, and the resulting devices will, as pointed out above and below, clearly have various different characteristics and uses in accordance with the present disclosure.

[0028] Example 1: Molecular sieve desiccant tablets having a unit amount of composition: The molecular sieve desiccant tablets comprise 1) 70 gm of molecular sieve 4A powder having a particle size between 100 mesh and 200 mesh, 2) 30 gm of attapulgite clay, and 3) 3 gm of magnesium stearate.

[0029] The specifications of the tablets are as follows. [Table 1]

[0030] Example 2: Process for preparing molecular sieve 4A desiccant tablets: A process for preparing molecular sieve 4A desiccant tablets is described below. 1) 70 g of powdered molecular sieve 4A having a particle size of 100 - 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. 2) 300 ml of distilled water is added to the above mixture under continuous stirring to obtain a uniform slurry. 3) This slurry is dried at 200 °C for 90 minutes to obtain a semi - dry mixture containing 15% moisture. 4) The semi - dry mixture is passed through an 18 - mesh sieve. 5) The semi - dry mixture is pressed in a tablet press at a pressure of 20 Kn. 6) The tablets prepared above are further heated to 550°C for 1 hour at a ramp rate of 40-200°C, held at 200°C for 30 minutes, then heated again at a ramp rate of 200-550°C for 1 hour, and finally held at 550°C for 30 minutes.

[0031] Example 3: Process for preparing Molecular Sieve 5A desiccant tablets: The process for preparing molecular sieve 5A desiccant tablets is described below. 1) Mix 72g of powdered molecular sieve 5A with a particle size of 100-200 mesh with 27g of attapulgite clay and 2.6g of magnesium stearate in an experimental blender to obtain a molecular sieve mixture. 2) Add 300 ml of distilled water to the above mixture under continuous stirring to obtain a homogeneous slurry. 3) Dry this slurry at 200°C for 90 minutes to obtain a semi-dried mixture containing 15% moisture. 4) Pass the semi-dried mixture through an 18-mesh sieve. 5) Press the semi-dried mixture with a tablet press at a pressure of 22 kN. 6) The tablets prepared above are further heated to 550°C for 1 hour at a ramp rate of 40-200°C, held at 200°C for 30 minutes, then heated again at a ramp rate of 200-550°C for 1 hour, and finally held at 550°C for 30 minutes.

[0032] Example 4: Process for preparing molecular sieve 13x desiccant tablets: The process for preparing molecular sieve 13x desiccant tablets is described below. 1) Mix 13 x 74 g of powdered molecular sieve having a particle size of 100-200 mesh with 29 g of attapulgite clay and 2.9 g of magnesium stearate in an experimental blender. 2) Add 300 ml of distilled water to the above mixture under continuous stirring to obtain a homogeneous slurry. 3) Dry this slurry at 200°C for 90 minutes to obtain a semi-dried mixture containing 15% moisture. 4) Pass the semi-dried mixture through an 18-mesh sieve. 5) Press the semi-dried mixture with a tablet press at a pressure of 25 kN. 6) The tablets prepared above are further heated to 550°C for 1 hour at a ramp rate of 40-200°C, held at 200°C for 30 minutes, then heated again at a ramp rate of 200-550°C for 1 hour, and finally held at 550°C for 30 minutes.

[0033] Example 5: Molecular sieve desiccant tablet moisture absorption capacity [Table 2] To observe the effect of increasing the diameter on the moisture adsorption capacity of tablets, tablets of different dimensions (9×5mm, 11×5mm, 12×5mm, and 16×5mm) were prepared. The final results suggested that there was little difference in the moisture adsorption performance of the tablet composition with respect to tablet size. The percentage of the specific weight increase of the tablets was directly proportional to the observed amount of tablet contents and relative humidity.

[0034] These and other embodiments will become apparent to those skilled in the art and others, given the following detailed descriptions of some embodiments. However, it should be understood that this summary and detailed description are merely illustrative of some examples of various embodiments and are not intended to limit the claimed invention.

[0035] Advantageously, the method for preparing molecular sieve desiccant tablets according to the present invention extends the lifespan of the desiccant. This method provides a homogeneous blend of the tablet components before tablet formation. In this method, the components, which are made into a slurry and mixed in water, ensure uniform mixing of the components. Molecular sieve desiccant tablets adsorb moisture under low relative humidity (RH) conditions (<20% RH). Furthermore, the partially moist mixture forms a strongly bound tablet that becomes even more mechanically stable after complete removal of moisture by drying. Thus, the present invention provides tablets with high mechanical strength without containing coating materials and without impairing the moisture adsorption capacity of the tablets. Tablets prepared by the method of the present invention do not use any polymer binders such as PVA, PVP, or EVA, and as a result, the tablets can be heated up to 550°C.

[0036] The embodiments are selected and described in a manner that best illustrates the principles and practical applications of the present invention, thereby enabling those skilled in the art to best utilize the present invention and various embodiments with various modifications suitable for specific intended uses.

[0037] Where circumstances may suggest or may be advantageous, various omissions and substitutions of equivalents are contemplated, but it is understood that these are intended to cover the application or implementation without departing from the scope of the invention.

Claims

1. A molecular sieve desiccant tablet characterized by adsorbing moisture under low relative humidity (RH) conditions (<20% RH), wherein the tablet is a) Molecular sieve powder having a particle size of 100 to 200 mesh, with 65% to 70% being b) 25% to 30% attapulgite clay, c) 2.5% to 3% magnesium stearate, Molecular sieve desiccant tablets containing this material.

2. The molecular sieve desiccant tablet according to claim 1, wherein the molecular sieve powder is selected from molecular sieve 4A powder, molecular sieve 5A powder, or molecular sieve 13x powder.

3. A process 100 for preparing molecular sieve desiccant tablets according to claim 1, a) A first step 110 in which molecular sieve powder of a certain particle size is uniformly mixed with attapulgite clay and magnesium stearate in a laboratory blender, b) A second step 120 in which water is added to the mixture from step 110 while continuously stirring to obtain a homogeneous slurry, c) A third step 130 in which the slurry is dried to obtain a semi-dried mixture, d) A fourth step 140 in which a dry mixture is pressed in a tablet press at a constant pressure to obtain tablets of a specific size, e) A fifth step 150 in which the tablets are heat-treated to remove residual moisture and obtain tablets with maximum mechanical strength, Process 100, including the process.

4. The process 100 according to claim 3, wherein in the fourth step 140, the tablet is pressed with a constant pressure of 20 kN to 25 kN.

5. The process 100 according to claim 3, wherein in the fifth step 150, the tablet is heated to 550°C for 1 hour at a ramp rate of 40 to 200°C, then held at 200°C for 30 minutes, then heated at a ramp rate of 200 to 550°C for 1 hour, and finally held at 550°C for 30 minutes.

6. Molecular sieve desiccant tablets according to claim 1, which exhibit moisture adsorption under low relative humidity (RH) conditions (<20% RH).

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