Composite drying agent as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of drying agents, and particularly relates to a composite drying agent and a preparation method and application thereof. The composite drying agent is prepared from magnesium oxide, magnesium chloride, calcium oxide and an aluminum-containing substance; the aluminum-containing substance comprises at least one of aluminate, aluminate cement, sulphoaluminate and bauxite. The drying agent disclosed by the invention has relatively high moisture absorption rate and does not generate a halogen accumulation phenomenon in a high-humidity state, and when the drying agent is applied to a security and protection monitoring product, the phenomenon that the security and protection monitoring product fogs due to too high humidity can be avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of desiccants, and in particular relates to a composite desiccant and a preparation method and application thereof. Background Art

[0002] Electronic products may suffer from metal oxidation due to excessive humidity, and the use of desiccant can avoid these defects. Security monitoring products among electronic products may have lens fogging due to excessive humidity, which will seriously affect the clarity of the monitoring image. This is absolutely not allowed in monitoring. Placing desiccant in the confined space of security products can solve this problem well.

[0003] The first type of desiccant currently used in security monitoring products is mainly silica gel and calcium oxide ball desiccant. The volume of this type of desiccant does not change after absorbing moisture, and the surface is dry, but the moisture absorption rate is too low (about 30%); the second type is mainly magnesium chloride / magnesium oxide desiccant. This type of desiccant appears as a hard block or loose small block after absorbing moisture, and when the moisture absorption rate reaches more than 200%, liquid water will reversely seep on the surface of the hard block, and the anti-halogen phenomenon will occur. The anti-halogen phenomenon is that when the air humidity is high, the surface of magnesium chloride and other products absorbs moisture in the air and becomes wet, and then is covered with water droplets, and even the water droplets appear to be connected into a piece to form a flow phenomenon. As the moisture absorption rate continues to increase, the liquid water content gradually increases. This is mainly because the crystals formed by the reaction of free magnesium chloride and magnesium oxide with water dissolve in water, resulting in a continuous increase in liquid water in the desiccant under high humidity conditions, increasing the risk of product leakage. Summary of the invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defect of the existing high moisture absorption rate desiccant that the dehalogenation phenomenon will occur under the condition of high air humidity, thereby providing a composite desiccant and its preparation method and application.

[0005] To this end, the present invention provides the following technical solutions:

[0006] The first aspect of the present invention protects a composite desiccant, wherein the composite desiccant is composed of magnesium oxide, magnesium chloride, calcium oxide and an aluminum-containing substance;

[0007] The aluminum-containing substance includes at least one of aluminate, aluminate cement, sulphoaluminate and bauxite.

[0008] According to the present invention, the composite desiccant comprises, by weight: 20-70 parts of magnesium oxide, 30-70 parts of magnesium chloride, 1-20 parts of calcium oxide, and 1-10 parts of aluminum-containing substances.

[0009] According to the present invention, the composite desiccant comprises, by weight: 30-50 parts of magnesium oxide, 45-55 parts of magnesium chloride, 2-6 parts of calcium oxide, and 2-4 parts of aluminum-containing substances.

[0010] According to the present invention, the aluminum-containing substance includes at least one of calcium aluminate, aluminate cement, calcium sulfoaluminate, and bauxite.

[0011] In the present invention, calcium aluminate is a compound composed of calcium oxide and aluminum oxide; aluminate cement has calcium aluminate as a main component; calcium sulfoaluminate is a compound composed of calcium oxide, aluminum oxide and calcium sulfate; and bauxite is a natural mineral containing aluminate.

[0012] According to the present invention, the aluminum-containing material includes calcium aluminate and / or aluminate cement.

[0013] According to the present invention, the magnesium oxide includes at least one of active magnesium oxide, light magnesium oxide and heavy magnesium oxide.

[0014] In the present invention, the magnesium chloride is conventional magnesium chloride in the art. For better moisture absorption rate, typically but not limitingly, the magnesium chloride is anhydrous magnesium chloride.

[0015] In the present invention, the particle sizes of the magnesium oxide, magnesium chloride, calcium oxide and aluminum-containing material are independently 60-300 meshes.

[0016] According to the present invention, the composite desiccant is a mixture, and the average particle size of the composite desiccant is 1-5 mm.

[0017] The second aspect of the present invention protects a method for preparing the aforementioned composite desiccant, which comprises the following steps: mixing the components of the composite desiccant, pressing into tablets, crushing, and screening to obtain the composite desiccant.

[0018] In the present invention, a mixer is used for mixing, and after the mixing is uniform, a crusher is used for crushing and screening. After screening, large particles and fine powders that do not meet the particle size requirements will be re-entered into the mixer for mixing. This operation can be performed multiple times until the average particle size of the composite desiccant meets the standard. The specific repetition here is the conventional level in the field and is determined according to specific requirements.

[0019] The third aspect of the present invention protects the use of the aforementioned composite desiccant or the composite desiccant prepared by the aforementioned preparation method in electronic products.

[0020] According to the present invention, the electronic product includes a security monitoring product and / or an LED vehicle lamp.

[0021] The technical solution of the present invention has the following advantages:

[0022] 1. The present invention provides a composite desiccant, wherein the composite desiccant is composed of magnesium oxide, magnesium chloride, calcium oxide and aluminum-containing substances; the aluminum-containing substances include at least one of aluminate, aluminate cement, sulphoaluminate and bauxite; the composite desiccant of the present invention can maintain or slightly reduce the moisture absorption rate without causing the dehalogenation phenomenon; the water absorption principle of the composite desiccant is the MgO-MgCl-HO ternary gelling system formed by magnesium oxide, magnesium chloride and water, that is, magnesium oxychloride cement (MOC), and the main hydration product is 5Mg(OH) 2 MgCl 2 8H 2 O phase (518 phase) and 3Mg(OH) 2 MgCl 2 8H 2 O phase (318 phase); but there will be free magnesium chloride in the system, so under high humidity conditions, anti-halogen effluent will appear. In order to remove these free magnesium chlorides, calcium oxide and aluminum-containing substances are added to achieve the purpose of removing free chloride ions. The main principle is that calcium oxide will form calcium hydroxide after absorbing water, and calcium hydroxide will react with free magnesium chloride to form magnesium hydroxide and calcium chloride. The produced magnesium hydroxide will combine with magnesium chloride to form 518 phase or 318 phase hydration products. The calcium chloride produced at the same time will react with aluminum-containing substances to form hydration products. Taking calcium aluminate as an example, the hydration reaction produces calcium monochloroaluminate (3CaO·Al 2 O 3 ·CaCl 2 10H 2 O), namely Friedel salt. In this way, there will be no free chloride ions in the system, ensuring that the desiccant always remains dry in a high humidity environment, preventing desiccant leakage, and at the same time not significantly reducing the desiccant's hygroscopic performance.

[0023] 2. The specific components in the composite desiccant of the present invention can further improve the moisture absorption rate of the composite desiccant, and have better moisture absorption performance under the condition of not meeting the requirement of anti-halogen.

[0024] 3. When the composite desiccant of the present invention is used in security monitoring products, it can prevent the security monitoring products from fogging due to excessive humidity, and there is no need to frequently replace the desiccant in the security monitoring products. Security monitoring products are often placed in high places, thus avoiding high-altitude operations, greatly improving efficiency, avoiding the risks of high-altitude operations, and reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 is an initial morphological image of the composite desiccant of Example 1;

[0027] Figure 2 This is the morphological image of the composite desiccant of Example 1 after absorbing moisture;

[0028] Figure 3 This is the initial morphological image of the composite desiccant of Comparative Example 1;

[0029] Figure 4 This is the morphological image of the composite desiccant of Comparative Example 1 after absorbing moisture. DETAILED DESCRIPTION

[0030] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0031] The "range" disclosed in the present invention is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The range defined in this way can be inclusive or exclusive of the end value, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. The numerical range "ab" represents an abbreviation of any real number combination between a and b, wherein a and b are both real numbers. For example, the numerical range "20-70" represents that all real numbers between "20-70" have been fully listed herein, and "20-70" is only an abbreviation of these numerical combinations. If a range of 20-70 is listed for a specific parameter, it is understood that the range of 20-50 and 30-60 is also expected. In addition, if the minimum range value 20 is listed and if the maximum range value 70 is listed, the following ranges can all be expected: 20-30, 20-40, 20-50, 20-60, 30-50 and 45-60. In the invention, unless otherwise stated.

[0032] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0033] In the present invention, the terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "the" and "said" used in the present invention are also intended to include plural forms, unless the context clearly indicates other meanings.

[0034] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0035] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0036] Calcium aluminate: Gongyi Chenyi Refractory Abrasive Co., Ltd., CA-50;

[0037] Aluminate cement: Zhengzhou Hongzheng Refractory Co., Ltd., CA-50-A600;

[0038] Bauxite: Zhengzhou Sijihuo Refractory Material Co., Ltd., SJH-aggregate;

[0039] In the embodiments and comparative examples of the present invention, 1 portion is 1 kg.

[0040] Example 1

[0041] This embodiment provides a composite desiccant, which specifically includes:

[0042] 45 parts of 200 mesh heavy magnesium oxide, 48 parts of 100 mesh anhydrous magnesium chloride, 5 parts of 200 mesh calcium oxide, and 2 parts of 200 mesh calcium aluminate were added into a mixer and mixed evenly. Then, the tablets were pressed by a roller press, and the pressed tablets were crushed and sieved to obtain a composite desiccant with an average particle size of 5 mm. The image of the obtained composite desiccant is as shown below. Figure 1 As shown, it can be seen from the figure that the composite desiccant is in a distinct granular state.

[0043] Example 2

[0044] This embodiment provides a composite desiccant, which specifically includes:

[0045] 42 parts of 200-mesh light magnesium oxide, 52 parts of 100-mesh anhydrous magnesium chloride, 4 parts of 200-mesh calcium oxide, and 2 parts of 200-mesh aluminate cement are added into a mixer and mixed evenly. The mixture is then pressed into tablets using a roller press. The pressed tablets are crushed and sieved to obtain a composite desiccant with an average particle size of 3 mm.

[0046] Example 3

[0047] This embodiment provides a composite desiccant, which specifically includes:

[0048] 18 parts of 200 mesh heavy magnesium oxide, 15 parts of 200 mesh active magnesium oxide, 10 parts of 200 mesh light magnesium oxide, 50 parts of 100 mesh anhydrous magnesium chloride, 5 parts of 200 mesh calcium oxide and 2 parts of 200 mesh bauxite are added into a mixer and mixed evenly, and then the mixture is pressed into tablets by a roller press, and the pressed tablets are crushed and sieved to obtain a composite desiccant with an average particle size of 1 mm.

[0049] Example 4

[0050] This embodiment provides a composite desiccant, which specifically includes:

[0051] 25 parts of 200 mesh heavy magnesium oxide, 15 parts of 200 mesh light magnesium oxide, 54 parts of 100 mesh anhydrous magnesium chloride, 3 parts of 200 mesh calcium oxide and 3 parts of 200 mesh calcium aluminate are added into a mixer and mixed evenly, and then the mixture is pressed into tablets by a roller press, and the pressed tablets are crushed and sieved to obtain a composite desiccant with an average particle size of 5 mm.

[0052] Example 5

[0053] This embodiment provides a composite desiccant, which specifically includes:

[0054] 10 parts of 200-mesh heavy magnesium oxide, 20 parts of 200-mesh active magnesium oxide, 50 parts of 100-mesh anhydrous magnesium chloride, 10 parts of 200-mesh calcium oxide, and 10 parts of 200-mesh calcium aluminate are added into a mixer and mixed evenly. The mixture is then pressed into tablets using a roller press. The pressed tablets are crushed and sieved to obtain a composite desiccant with an average particle size of 5 mm.

[0055] Example 6

[0056] This embodiment provides a composite desiccant, which specifically includes:

[0057] 20 parts of 200-mesh active magnesium oxide, 55 parts of 100-mesh anhydrous magnesium chloride, 20 parts of 200-mesh calcium oxide, and 5 parts of 200-mesh calcium aluminate are added into a mixer and mixed evenly. The mixture is then pressed into tablets using a roller press. The pressed tablets are crushed and sieved to obtain a composite desiccant with an average particle size of 5 mm.

[0058] Comparative Example 1

[0059] This comparative example provides a composite desiccant, which is in the manner of Example 1, except that "45 parts of 200 mesh heavy magnesium oxide, 48 parts of 100 mesh anhydrous magnesium chloride, 5 parts of 200 mesh calcium oxide, and 2 parts of 200 mesh calcium aluminate" are changed to "45 parts of 200 mesh heavy magnesium oxide, 48 parts of 100 mesh anhydrous magnesium chloride"; the image of the obtained composite desiccant is as follows: Figure 3 As shown in the figure, it can be seen that most of the composite desiccant is in granular state, and a small part is in agglomerate.

[0060] Comparative Example 2

[0061] This comparative example provides a composite desiccant, which is prepared in the manner of Example 1, except that "45 parts of 200 mesh heavy magnesium oxide, 48 parts of 100 mesh anhydrous magnesium chloride, 5 parts of 200 mesh calcium oxide, and 2 parts of 200 mesh calcium aluminate" are changed to "45 parts of 200 mesh heavy magnesium oxide, 48 parts of 100 mesh anhydrous magnesium chloride, and 7 parts of 200 mesh calcium aluminate".

[0062] Comparative Example 3

[0063] This comparative example provides a composite desiccant, which is prepared in the manner of Example 1, except that "45 parts of 200 mesh heavy magnesium oxide, 48 parts of 100 mesh anhydrous magnesium chloride, 5 parts of 200 mesh calcium oxide, and 2 parts of 200 mesh calcium aluminate" are changed to "45 parts of 200 mesh heavy magnesium oxide, 48 parts of 100 mesh anhydrous magnesium chloride, and 7 parts of 200 mesh calcium oxide".

[0064] Test Case

[0065] Hygroscopicity test: The granular desiccant prepared in the embodiment and the comparative example was subjected to a hygroscopicity test. The test conditions were: humidity 90%, temperature 35°C, constant temperature and humidity for 7 days, the initial weight and weight after moisture absorption of the solid desiccant were recorded, and the moisture absorption rate was calculated. Moisture absorption rate = weight after moisture absorption / initial weight × 100%, and the particle state and the dehalogenation of the liquid were observed after moisture absorption, the moisture absorption morphology was recorded, and the moisture absorption rate was tested 5 times and the average value was taken. The specific test results are shown in Table 1.

[0066] Table 1

[0067]

[0068]

[0069] From Table 1 and Figure 2 It can be seen from Table 1 that the composite desiccant in Example 1 after moisture absorption is in a clumped particle state; Figure 4 It can be seen that the composite desiccant particles in Comparative Example 1 agglomerated and appeared slurry after absorbing moisture.

[0070] No calcium oxide and aluminum-containing substances were added in Comparative Example 1. By comparing Example 1 with Comparative Example 1, it can be seen that although the moisture absorption rate in Example 1 is slightly reduced, there is no dehalogenation phenomenon on the surface of the desiccant after moisture absorption, and the desiccant still maintains agglomerated particles, which can meet the requirement of long-term moisture absorption, while the particles in Comparative Example 1 are agglomerated and slurry-like and cannot meet the requirements.

[0071] Comparison of Example 1 with Comparative Examples 2 and 3 shows that there is a synergistic effect between calcium oxide and aluminum-containing substances, and using them together can avoid the dehalogenation phenomenon.

[0072] Obviously, the above embodiments are merely examples for clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, it should be clear that the described embodiments are only some embodiments of the present invention, rather than all embodiments. Other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the protection scope of the invention.

Claims

1. A composite desiccant, characterized in that: The composite desiccant is composed of magnesium oxide, magnesium chloride, calcium oxide and aluminum-containing substances; The aluminum-containing substance includes at least one of aluminate, aluminate cement, sulphoaluminate and bauxite.

2. The composite desiccant according to claim 1, characterized in that: The composite desiccant comprises, by weight: 20-70 parts of magnesium oxide, 30-70 parts of magnesium chloride, 1-20 parts of calcium oxide, and 1-10 parts of aluminum-containing substances.

3. The composite desiccant according to claim 2, characterized in that: The composite desiccant comprises, by weight: 30-50 parts of magnesium oxide, 45-55 parts of magnesium chloride, 2-6 parts of calcium oxide, and 2-4 parts of aluminum-containing substances.

4. The composite desiccant according to claim 1, characterized in that: The aluminum-containing substance includes at least one of calcium aluminate, aluminate cement, calcium sulfoaluminate, and bauxite.

5. The composite desiccant according to claim 4, characterized in that: The aluminum-containing material includes calcium aluminate and / or aluminate cement.

6. The composite desiccant according to claim 1, characterized in that: The magnesium oxide includes at least one of active magnesium oxide, light magnesium oxide and heavy magnesium oxide.

7. The composite desiccant according to claim 1, characterized in that: The average particle size of the composite desiccant is 1-5 mm.

8. A method for preparing the composite desiccant according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: mixing the components of the composite desiccant, pressing into tablets, crushing and screening to obtain the composite desiccant.

9. Use of the composite desiccant according to any one of claims 1 to 7 or the composite desiccant prepared by the preparation method according to claim 8 in electronic products.

10. The use according to claim 9, characterized in that: The electronic products include security monitoring products and / or LED car lights.

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