JP2010105852A - Method of producing high strength zeolite bead molded body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems that a bead molded body formed from zeolite and a clay binder by tumbling granulation has low strength and low wear resistance, is easily pulverized in the use. <P>SOLUTION: The zeolite-bead molded body having ≥70 N hydration pressure withstanding strength and ≤1.5% wear resistance ratio is obtained by bead-molding a mixture containing ≥35 pts.wt. water with 100 pts.wt. in total of zeolite and the clay binder by tumbling granulation, making the water content of the molded body once to <35 pts.wt. and after that, making the water content of the molded body to ≥35 pts.wt. and tumbling-granulating to regulate particle size, drying and firing. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a zeolite bead molded body having high strength and particularly high wear resistance. For example, a zeolite bead molded body used for a Freon desiccant for an air conditioner of an automobile is required to have particularly high strength and wear resistance so as not to be pulverized by vibration of an engine drive.

  Zeolite bead moldings are widely used as desiccants, but recently, the demand for desiccants for automobile air conditioners is increasing. Since air conditioners for automobiles are exposed to vibration during use, if the strength and wear resistance are low, powdering may cause clogging, and a desiccant with high strength and high wear resistance is required.

  As a method of obtaining a desiccant having high strength and high abrasion resistance, for example, a method using an additive such as condensed phosphate as a binder, a method using a special needle-like crystal binder as a binder (Patent Document 2), A method of treating with an alkaline compound (Patent Document 3, Patent Document 4) and the like have been proposed. However, all of these methods require special raw materials and special processing steps, and have been the cause of increased costs for desiccants.

  In any of the methods, it has been pointed out that the obtained molded body particles are sized to smooth the surface of the molded body and increase the sphericity, but a sufficient effect has not been obtained.

  In addition, there is also known a method (Patent Document 5) in which a high-strength pellet molded body is rounded by rolling sizing. In such a method, particles having high strength can be obtained, but a molded product having a high sphericity cannot be obtained.

JP 2001-261330 A JP-A-11-314913 Japanese Patent Laid-Open No. 4-198012 JP-A-6-327968 JP-A-10-87322

  An object of the present invention is to provide a method for improving the strength and wear resistance of a bead molded product of zeolite, particularly 3A type zeolite (K ion exchange type A zeolite) and clay binder, without using special raw materials and processes. Is.

  As a result of intensive studies on the improvement of the strength (hydration pressure strength) and abrasion resistance of the zeolite bead molded body, the present inventors have determined that the water content of the bead molded body after granulation is 35 parts by weight (molding). The amount of water during sizing is adjusted to 35 parts by weight or more (based on 100 parts by weight of zeolite and clay binder in the molded body). As a result, it has been found that the hydration pressure resistance and wear resistance of the molded product are remarkably improved, and the present invention has been completed.

  Hereafter, the manufacturing method of the zeolite bead molded object of this invention is demonstrated.

  In the method for producing a zeolite bead molded body of the present invention, a composition containing 35 parts by weight or more of moisture with respect to 100 parts by weight of a zeolite and a clay binder is formed into a bead (spherical) molded body by rolling granulation, After the water content of the bead molded body is set to less than 35 parts by weight, water is further added, the sizing is performed at a water content of 35 to 45 parts by weight, dried, and fired.

  If the amount of water relative to the zeolite and clay binder during rolling granulation is too small, a molded body cannot be obtained, and if too much, the molded bodies adhere to each other and grow abnormally. The amount of water relative to 100 parts by weight of the zeolite and clay binder during granulation is 35 parts by weight or more, particularly in the range of 35 to 60 parts by weight, although there are some adjustments in the particle size and surface area of the clay binder used. Is preferred.

  In the present invention, the composition having the water content is first rolled and granulated into a spherical shape (bead shape) to obtain a molded body having a water content of less than 35 parts by weight.

  In the method of the present invention, the moisture content in the molded body is less than 35 parts by weight (relative to 100 parts of zeolite and clay binder in the molded body) after rolling granulation under conditions that do not cause peeling and pulverization of the molded body surface. In particular, it is once adjusted to a range of 30 to 35 parts by weight. Although the moisture adjustment method is not particularly limited, for example, natural drying by standing or hot air drying in a drier may be performed, and natural drying is particularly preferable.

  In the method of the present invention, the water content in the molded body is reduced to less than 35 parts by weight by the above-described method, and then water is added again for rolling sizing. The water content at the time of rolling sizing is preferably 35 parts by weight or more, particularly 35 to 45 parts by weight (based on 100 parts of the zeolite and clay binder in the molded body).

  It is known that a zeolite bead molded body containing a clay binder improves the strength and wear resistance to some extent by smoothing the surface of the molded body by sizing (rolling sizing). However, conventional sizing is intended to remove foreign substances adhering to the surface of the molded body and smooth the surface, and its effect is limited.

  Generally, at the time of rolling granulation, with the molding and densification of the bead molding, the temperature rises mainly due to the friction between the moldings, and the water content decreases. If rolling granulation is continued in a state where the water content is reduced, the dry surface of the molded body is peeled off and pulverization occurs, and the strength and wear resistance of the molded body are reduced. On the other hand, when granulation and granulation are performed while maintaining the water content within a certain range by adding water that volatilizes in the process of granulation to rolling regulation, powdering and surface peeling due to drying can be prevented. The water in the molded body hinders the bonding between the zeolite and the clay binder and the pore shrinkage, and the strength and wear resistance due to the sizing cannot be sufficiently improved.

  In the present invention, the moisture that worked as a binder at the time of granulation is once removed from the inside of the molded body after granulation, and then added separately at the time of granulation to regulate the size of the molded body by the sizing operation. In addition, the wear resistance is remarkably improved.

  Molding and sizing in the present invention are not particularly limited as long as a bead molded body can be molded, and any of a general rolling granulator, drum granulator, and rotary cylindrical granulator can be used.

  The zeolite used in the present invention is not particularly limited, but when used as a desiccant for an automotive air conditioner, it is preferably a K ion exchange type A zeolite that does not adsorb chlorofluorocarbon and selectively adsorbs only moisture.

  3A-type zeolite powder is obtained by a known method, that is, sodium A-type zeolite powder synthesized from sodium aluminate and sodium silicate is exchanged with potassium ions in potassium chloride aqueous solution, and 35% or more of sodium ions in the zeolite are exchanged with potassium ions. The 3A-type zeolite powder having an effective pore diameter of 3 angstroms can be obtained.

  The clay binder for the zeolite used in the present invention is not particularly limited. And a general-purpose kaolin clay. The amount of the clay binder added to the zeolite is preferably 10 parts by weight or more and 50 parts by weight or less, and particularly preferably 30 parts by weight or more and 45 parts by weight or less with respect to 100 parts by weight of the zeolite (excluding moisture). When the amount of the binder is too small, the strength is insufficient, and when it is too large, the performance as a desiccant per unit weight is lowered.

  The diameter of the molded bead of the present invention is preferably 1.0 to 3.0 mm, particularly preferably 1.4 to 2.5 mm. If the diameter is less than 1.0 mm, sufficient strength cannot be obtained, and if it exceeds 3.0 mm, a sufficient adsorption / desorption rate cannot be obtained, so that the performance as an adsorbent is lowered.

  In the present invention, as long as the performance as a desiccant is not adversely affected, in addition to the clay binder, a dispersant and a molding aid (an auxiliary agent such as CMC) may be included.

  The conditions for drying and calcination in the production method of the present invention are not particularly limited, but the zeolite is hydrothermally deteriorated when calcinated in a dry state with a high water content or calcinated at a high temperature. Performance decreases. The moisture content at the time of drying is 10 to 25% in terms of ig-loss, and the firing temperature is in the range of 600 to 700 ° C. for several hours to 10 hours.

  As drying and activation methods, known methods can be used. For example, a hot air dryer, an electric muffle furnace, a tubular furnace, a rotary furnace, etc. may be used.

  In the method of the present invention, the zeolite crystal diameter is 5 μm or less, the clay binder is 10 parts by weight or more and less than 50 parts by weight, the hydration pressure strength is 70 N or more (= 7.14 kgf or more), the wear resistance is 1.5% or less, A zeolite bead molded product having an average diameter in the range of 1.0 to 3.0 mm can be obtained.

  The zeolite crystal diameter is preferably 5 μm or less, particularly 3 to 5 μm. The zeolite crystal diameter can be confirmed by SEM observation. When the zeolite crystal diameter is larger than 5 μm, the wear resistance tends to be lowered.

  The clay binder is 10 parts by weight or more and 50 parts by weight or less, and particularly preferably 30 parts by weight or more and 45 parts by weight or less with respect to 100 parts by weight of zeolite (excluding moisture). The clay binder used is a plate-like crystal, preferably having a crystal size comparable to or smaller than that of the zeolite particles. If the binder is less than 10 parts by weight, the strength and wear resistance are insufficient, and if it exceeds 50 parts by weight, the performance as a desiccant (adsorbent) decreases.

  The particle size of the zeolite bead molded body is in the range of 1.0 to 3.0 mm, and particularly preferably in the range of 1.4 to 2.5 mm.

  Since the zeolite bead molded body obtained by the method of the present invention is not added (impregnated) with a conventional vitrifying agent such as sodium silicate, it has excellent toughness and does not block the pores of the molded body due to the vitrifying agent. Therefore, the adsorption performance is excellent. Whether or not it is a molded body to which a vitrifying agent such as sodium silicate is added can be confirmed by confirming the structure with an electron microscope.

  The zeolite bead molded body of the present invention has a hydration pressure strength of 70 N or more (= 7.14 kgf or more) and an abrasion resistance of 1.5% or less. The wear resistance is particularly preferably 1% or less. The pressure strength and wear resistance of the present invention are both strengths in a hydrated state (phase humidity 80%). In a dry (non-hydrated) state, even higher pressure strength and wear resistance are exhibited, but in practice, strength and wear are problematic in a state of advanced hydration. In the present invention, it is significant that strength and wear resistance are high in a hydrated state.

  The hydration pressure strength in the present invention is based on a crushing strength test method for a granulated product described in a granulated product-strength test method described in JIS-Z-8841 for a sample hydrated at a relative humidity of 80%. It is a measured value, and the abrasion resistance is measured by a weight reduction ratio by shaking for 1 hour with a general-purpose paint conditioner using 100 ml of a hydrated sample and 55 ml of an organic solvent (trichloroethylene) for testing. .

  In the method of the present invention, a zeolite bead molded body having a high hydration strength and a remarkably low wear rate can be obtained.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.

(Measurement method of strength (hydration pressure strength))
The zeolite bead molded body hydrated at 80% relative humidity is measured based on the granulated product crushing strength test method described in the granulated product-strength test method described in JIS-Z-8841. The maximum load that the zeolite bead compact can withstand when a compression load is applied by pressing the pressure plate at a constant speed in the diameter direction of the granular material, which is a test piece, in a normal temperature and normal pressure atmosphere using a hardness meter. Measure.

  In the present invention, a fired zeolite bead molded body having a diameter of 1.4 mm to 2.4 mm is used to measure the pressure strength in the diametrical direction of a cylindrical column having a diameter of 5 mm, using a Kiya digital hardness meter (KHT-20 type). Measured with a pressure plate. A pressure plate made of stainless steel was used, and 25 pressure-resistant strengths were measured.

(Measurement method of wear rate)
Measure the weight loss after loading 100 ml of zeolite bead hydrated at 80% relative humidity and 55 ml of trichloroethylene into a screw mouth bottle (130 ml) and shaking with a paint shaker (Toyo Seiki Seisakusho) for 1 hour. did. After shaking, wear particles are separated with a 1 mm sieve and the change in weight is measured.

Example 1
40 parts by weight of kaolin clay is mixed with 100 parts by weight of zeolite (K ion exchange A-type zeolite), 50 parts by weight of water is mixed with 100 parts by weight of zeolite and clay, and molded by rolling granulation. A preform of 1.7 mmφ was obtained by sieving. The water content of the preform after molding (calculated as ig-loss at 900 ° C. firing) was 36 parts by weight. The molded body was allowed to stand and dried to adjust the water content to 30 parts by weight, and then sprayed with water again to perform rolling sizing with a water content of 37 parts by weight. The rolling sizing was performed at 26 rpm for 70 minutes using a pot mixer (460 mmφ). Then, it dried further and baked at 680 degreeC for 5 hours.

  The properties of the obtained bead molded body are shown in Table 1.

Comparative Example 1
The preformed body obtained in Example 1 was dried as it was and fired under the same conditions as in Example 1.

  The properties of the obtained bead molded body are shown in Table 1. Only molded articles with low hydration pressure strength and wear resistance were obtained.

Claims (4)

A composition containing 35 parts by weight or more of moisture with respect to 100 parts by weight of zeolite and clay binder is formed into a bead molded body by rolling granulation, and the water content of the bead molded body is less than 35 parts by weight. A method for producing a zeolite bead molded product, further comprising adding water and rolling and regulating the water content to 35 to 45 parts by weight, followed by drying and firing. The manufacturing method of Claim 1 which dries a molded object before rolling sizing. The production method according to any one of claims 1 to 3, wherein the clay binder with respect to zeolite is 10 parts by weight or more and 50 parts by weight or less. 4. The production method according to claim 1, wherein the zeolite is K ion exchange type A zeolite.