JPH0435201B2 - - Google Patents

Description

[Detailed description of the invention]

(Purpose and Background) The present invention relates to an adsorbent that is easy to handle and has excellent adsorption performance for adsorbing odors and other trace components in air or fluids such as water. Activated carbon, activated clay,
Activated alumina, powdered silica gel, etc. are used, but these are generally powders or granules and are not necessarily easy to handle. Therefore, attempts have been made to produce an adsorbent in which these adsorbent particles are fixed to a porous material such as a foam material or a nonwoven fabric. These materials are convenient to handle because they do not have the risk of scattering like powder or granules, and have the advantage of low resistance because the fluid can freely flow through the voids in the porous material. However, such conventionally produced adsorbents exhibit only a small portion of the original adsorption capacity of the adsorbent adhered thereto. As a result of investigating the cause, the present inventor found that this is caused by the microstructure of the adsorbent, and further traced back to its manufacturing method. Here, a conventional method for manufacturing an adsorbent will be briefly explained. In other words, when adsorbent particles such as activated carbon are directly filled into the voids of a porous material such as polyurethane foam, there is almost no adhesion force, so the filled adsorbent particles tend to scatter when handled, which is inconvenient in practice. be. Here, various attempts have been made to fix adsorbent particles to porous bodies. One such attempt is to incorporate adsorbent particles such as activated carbon during the production of polyurethane foam. In this method, if enough adsorbent particles are added, the foaming properties of the polyurethane foam itself tend to be inhibited, and the carefully blended adsorbent particles may be coated with urethane resin, or the fine pores of the adsorbent may be Since a considerable portion of the water becomes clogged, the adsorption effect is significantly inhibited. Another attempt is to impregnate a porous body with an adhesive (binder) in which adsorbent particles are mixed and adhere to the porous body. Even in this method, the adsorbent particles are coated with the binder and a considerable portion of the fine pores of the adsorbent are clogged, so that the adsorption effect is significantly inhibited. Conventional adsorbents with adsorbent particles fixed to them in this way have a large amount of adsorbents, but
In its microstructure, the entire surface of each adsorbent particle is coated with urethane resin or binder, and a considerable portion of the adsorbent's micropores are clogged. In addition, it was found that only a small portion, for example, less than 10% of the original adsorption capacity predicted from the amount of adsorbent attached was expressed. Based on this recognition, the present invention provides an adsorbent that improves the drawbacks of conventional products, is easy to handle, and has excellent adsorption performance. (Structure) That is, the present invention provides an adsorbent in which adsorbent particles are fixed to a polyurethane foam. Part of it touched and stuck, and the rest was exposed.
This is an adsorbent having adsorbent particles having an average particle diameter of 1/50 or more and 1.5 or less of the average interskeletal distance of polyurethane foam. In conventional adsorbents, the polyurethane raw material or binder and adsorbent particles are mixed in advance during production, which may result in coating of the adsorbent particle surface with the resin component or clogging of the adsorbent's fine pores, reducing the adsorption capacity. However, if adsorbent particles are fixed to a non-solvent binder layer coated on polyureta foam in advance as in the present invention, each adsorbent particle will partially contact the binder layer. Since most of the surface remains exposed without touching the binder, most of the adsorption ability of the adsorbent particles is exhibited as is. In this case, the average particle size of the adsorbent particles is equal to the average interskeletal distance (pore size) of the polyurethane foam used.
If the average particle size is 1/50 (67%) or more of the pore diameter, the skeletal structure of the porous material will be damaged even if adsorbent particles are sprayed from the surface. It is difficult to penetrate the inside of the substrate, and most of the adsorbent particles adhere near the surface of the base material, and the adhesion force is weak, so the adhered adsorbent particles easily fall off. This seems to be because the area of the adhering portion to the polyurethane foam is relatively small compared to the size of the adsorbent particles. Furthermore, when the average particle diameter is less than 1/50 (2%) of the pore diameter, the amount of adsorbent adhering to the polyurethane foam is significantly reduced. This is thought to be because the fine adsorbent particles thinly cover the binder applied to the polyurethane foam and do not adhere any further, reducing the absolute amount of adhesion. As a result, the adsorption capacity of the adsorbent as a whole decreases, and the adsorption capacity is only comparable to that of an adsorbent produced by the conventional method (a method in which adsorbent particles and a binder are mixed and deposited). That is, the average particle size is 1/50 (2%) or more of the pore size,
The value of 1/1/5 (67%) or less was set as a condition that allows the adsorbent particles to be dispersed and fixed even inside the porous material and to obtain an adsorbent with higher adsorption capacity than conventional products. Furthermore, considering the need to maintain air permeability and increase the absolute amount of adsorption, the average particle size should be set to 1/10 (10%) or more of the pore size, or 1/2 of the pore size.
(50%) or less is more preferable. (Example 1
~4 and Comparative Examples 1 and 2) The particle size distribution of the adsorbent particles actually used is
Use particles in which 95% by weight or more is 1/5 to 5 times, preferably 1/2 to 2 times, the average particle size. The above are the basic constituent requirements of the adsorbent according to the present invention, but depending on the usage conditions, thermal or physical force is applied and the adsorbent material is repeatedly deformed, bent, etc. Adsorbent particles that are broken and adhered to the surface layer of the adsorbent may fall off and scatter. In order to eliminate such inconveniences, a non-solvent binder may be further applied to the surface layer of the above-mentioned adsorbent. In this case, the surface of the adsorbent particles adhering to the surface layer of the base material will be coated with a non-weldable binder, and the adhesion force to the polyurethane foam will increase, but the adsorption capacity of the adsorbent particles in that area will be reduced. descend. However, most of the adsorbent particles fixed to the inner layer of the polyurethane foam were not affected by the binder applied to the surface layer of the polyurethane foam, and the adsorption capacity of the adsorbent as a whole did not decrease significantly (see Examples 9 and 10). The thickness of the surface layer to be applied can be adjusted arbitrarily depending on the amount of non-welding binder applied, so take into account the increase in the adhesion force of the adsorbent particles on the surface layer and the decrease in the adsorption capacity of the entire adsorbent. It may be determined as appropriate. The thicker the polyurethane foam, the smaller the rate of decrease in adsorption capacity due to surface coating. The non-solvent binder applied to the surface layer may be the same as the non-solvent binder initially applied to the entire polyurethane foam. The combination effect can be obtained by using a rigid non-solvent binder with a strong adhesion force to avoid interfering with the surface layer. It is also advantageous in terms of air permeability to intentionally use an emulsion type binder that tends to cause defects (pinholes, etc.) in the film. The polyurethane foam is preferably a flexible polyurethane foam or a reticulated polyurethane foam from which the foam film has been removed. The air permeability of polyurethane foam is JIS L1004−
It is preferable to use a material whose passing air amount (cm ³ /cm ² /sec) measured by a Frazier type tester based on 1972 (Testing Methods for Cotton Fabrics) is 150 or more, preferably 250 or more when measured at a thickness of 10 mm. As adsorbent particles, adsorbent particles that have been put into practical use such as activated carbon, activated clay, activated alumina, and powdered silica gel can be arbitrarily selected depending on the purpose of use.
Although it can be used, activated carbon is commonly used due to its versatility. Various types of non-solvent binders are also selected as appropriate.
However, in order to achieve the purpose of the present invention, it is preferable that the adsorbent particles have a strong adhesive force and are unlikely to clog the pores of the adsorbent particles. Select a non-solvent binder with a low solids content, ie at least 30% by weight, preferably at least 50% by weight. To give a specific example, a urethane prepolymer with excess NCO is used, more preferably a urethane prepolymer based on MDI (methylene diisocyanate). MDI-based prepolymers are better
Compared to TDI (tolylene diisocyanate)-based products, free isocyanate is less likely to be generated, less adsorption to adsorbent particles occurs, and there are fewer hygiene problems in the manufacturing process. When using a urethane prepolymer with an excess of NCO as a binder, if the viscosity is too high as it is, add the minimum necessary amount of organic solvent and apply after blowing off most of the organic solvent with dry warm air.
Adhering adsorbent particles is advantageous because it facilitates processability and prevents solvent adsorption. The binder is applied by impregnating the base material in an impregnating tank and then squeezing out the excess binder with a roll.
There are methods such as applying it to the surface with a spray or coater and then squeezing it with a roll to spread it to the inside.
In order to attach adsorbent particles to the polyurethane foam coated with a binder in advance in this manner, methods such as adsorbent fluidized bed immersion, powder spraying, or sieve dropping are used. When using powder spray or sieve drop methods, uniform adhesion can be achieved by spraying or dropping adsorbent particles from both sides of the polyurethane foam by, for example, inverting the polyurethane foam. Vibrating the polyurethane foam during and/or after the adsorbent particles are attached can help the adsorbent particles penetrate into the polyurethane foam and reliably adhere to the polyurethane foam skeleton. Furthermore, after the adsorbent particles have been attached, they can be passed between one or more sets of rolls and lightly compressed to help the adsorbent particles adhere to the polyurethane foam skeleton. In this case, it is appropriate that the roll spacing be 90 to 60% of the thickness of the polyurethane foam. To solidify a non-solvent binder, you can use a method suitable for each binder, but when using a urethane prepolymer, it can be cured with heated steam, which simplifies the process and provides a high adhesive strength. is obtained. Furthermore, when a portion of the adsorbent is coated with a non-solvent binder, the adsorption power is less likely to decrease because fine pores are created in the coating due to the carbon dioxide gas generated during curing of the urethane. Before or after fixing this coated binder, a method such as spraying a non-solvent binder on the surface layer of the polyurethane foam as described above can be used to obtain a product in which adsorbent particles attached to the surface layer are strongly fixed. I can do it. In addition, the volume of the adsorbent of the present invention can be reduced by heat pressing or the like to increase the adsorption capacity per unit volume of the adsorbent, and by molding at the same time, it can be shaped into a shape convenient for holding and attaching the adsorbent. can do. Further, a plurality of adsorbents according to the present invention may be laminated and used, or two or more types of adsorbents using polyurethane foams having different materials, pore sizes, etc. may be laminated and used. In addition, in order to protect the adsorbent and prevent it from getting dirty, a breathable foam, knitted fabric, woven fabric, non-woven fabric, etc. can also be bonded together. Examples 1 to 4 and Comparative Examples 1 and 2 Polyurethane foam with an average interskeletal distance (pore diameter) of 2.5 mm (15 mm thickness x 100 mm x 100 mm, amount of air passing through)
300 or more, weight 4.2 g), and a non-solvent binder (prepolymer of carbodiimide modified MID and polypropylene glycol) of the same weight as the foam was impregnated and coated. This has an average particle size of 2.2
mm, 1.5mm, 0.6mm, 0.3mm, 0.1mm, and 0.02mm coconut shell activated carbon (manufactured by Fujisawa Pharmaceutical Co., Ltd., ACW,
8 to 32 mesh was crushed using a ball mill and sieved using a precision sieve for analysis) was sprayed with a powder spray, and then sprayed in the same manner from the back side. Next, the non-adherent activated carbon was sieved off by vibration, and the adhesion of the adhering activated carbon was strengthened. For each case, the amount of activated carbon adhesion (g) was measured, the internal adhesion degree and adhesion force were determined, and the adsorption capacity was measured. The adsorption capacity was measured based on the equilibrium adsorption amount of benzene based on JIS K1474-1975. Prototype sample is 15mm x 15mm
Cut into 15mm dice and put 6 into a U-shaped tube.
Sample when air containing benzene vapor is passed through at a rate of 2/min and the weight remains constant (20.25cc)
The increased weight was taken as the equilibrium adsorption amount. The results are summarized in Table 1.

[Table] Activated carbon average particle size is 2.2mm (particle size/pore size ratio 88%)
In the case of (Comparative Example 1), the amount of activated carbon adhering was large and the adsorption capacity was high, but only a small amount of activated carbon adhered inside the foam skeleton, and most of it adhered near the surface layer of the foam, and the adhesion force was weak. Ta. In addition, the activated carbon average particle size is 0.02 mm (particle size/pore size ratio
0.8%) (Comparative Example 2), the amount of adhesion was small because the fine activated carbon particles thinly covered the binder, and the adsorption capacity was only slightly better than that of the conventional method (Comparative Example 3). Those having an average particle size/pore size ratio in between these (Examples 1 to 4) showed good results with a good balance between adhesion and adsorption ability. Comparative Example 3 (corresponding to Example 2) The same amount of activated carbon (average particle size 0.6 mm) used in Example 2 was added to the binder used in Examples 1 to 4 and mixed, and the polyurethane used in Example 2 was mixed. Knead it into a foam and squeeze out the excess with a roll. 6 g of binder and 6 g of activated carbon were attached to a 15 mm x 100 mm x 100 mm foam. After curing the binder, the adsorption capacity was measured and it was 0.03.
g/20.25cc. This seems to be because the pores of the activated carbon were clogged with the binder, or the surface was coated with the binder, making it inactive. Examples 5 to 6 Polyurethane foam with an average distance between skeletons of 1.3 mm (15 mm thickness x 100 mm x 100 mm, passing air 300 or more, weight
After applying the same binder as used in Examples 1 to 4 in the same weight as the foam, coconut shell activated carbon with an average particle size of 0.6 mm and 0.3 mm (in Examples 1 to 6) was used. (same as used) was fixed. Table 2 shows the results of measuring adsorption capacity and other properties.

[Table] Examples 7 to 8 Polyurethane foam with an average interskeletal distance of 0.6 mm (passing air of 300 or more, weight 4.1 g) was used, the binder impregnated amount was 4.2 g, and the average particle diameter was 0.3 mm and 0.1 mm.
Examples 5 to 6 except that activated carbon was used from coconut shells.
The adsorbent was made using the same method. The adsorption capacity and other measured results are shown in Table 3.

[Table] Example 9 The same sample as Example 2 was created, and before curing the non-solvent binder that was originally applied, the temperature of the same binder that was originally applied was raised to 60°C (to lower the viscosity). Then, use air spray to remove the foam.
Sprayed from both sides. Spray amount is 50g/
Each portion was equivalent to ^100m2 , for a total of 100g/ ^m2 . The increase in the inactivated area due to the surface coating was surprisingly small, and the adsorption capacity was 0.20 g/20.25 cc, and the adhesion to the foam was improved. Example 10 The same sample as Example 2 was prepared, and after curing the initially applied non-solvent binder with heated steam, acrylic emulsion (manufactured by Japan Synthetic Rubber Co., Ltd., AE331, solid content 55%) was applied. Form table/
A total amount equivalent to 200 g/m ² was sprayed from the back side at a time of 100 g/m ² to evaporate the water. The increase in the inactivated portion is surprisingly small and the adsorption capacity is 0.21g/20.25
cc, and the adhesion to the foam was improved. Example 11 Same sample as Example 2 (but thickness 30mm)
was pressed at 200°C for 5 minutes to obtain a product with a thickness of 15 mm.
The adsorption capacity was 0.39g/20.25cc, which is about 70% more adsorption capacity per unit volume than the original adsorbent. (Effects) As shown in Examples 1 to 11, the adsorbent of the present invention has adsorbent particles stably fixed, has a high adsorption ability, and can be freely subjected to surface treatment, thermoforming, etc.

Claims (1)

[Scope of Claims] 1. An adsorbent comprising adsorbent particles fixed to polyurethane foam, comprising: a non-solvent binder layer coated on the surface and inside of the porous skeleton structure of the polyurethane foam; 1.5 or more than 1/50 of the average interskeletal distance of the polyurethane foam, where the parts are in contact and fixed and the rest is exposed.
Adsorbent particles having an average particle diameter of 1/2 or less. 2. In an adsorbent material in which adsorbent particles are fixed to a polyurethane foam, a non-solvent binder layer is coated on the surface and inside of the porous skeleton structure of the polyurethane foam, and a part of the adsorbent particles comes into contact with the binder layer and becomes fixed. 1.5 or more than 1/50 of the average distance between the skeletons of the polyurethane foam, with the remainder exposed.
An adsorbent having adsorbent particles having an average particle diameter of 1/2 or less and having a non-solvent binder coated on the surface layer.