JPS6133602B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a granular oil adsorbent made of a lipophilic thermoplastic resin. More specifically, the present invention relates to a granular oil adsorbent useful as a filler having excellent water permeability and oil absorption, and which is particularly suitable for removing oil from an oil/water mixture by overtreatment. In recent years, the problem of environmental pollution of oceans, rivers, etc. due to oil has become important, but oil in wastewater discharged from factories, hotels, gas stations, etc. is also becoming a problem and needs to be removed. sex is increasing. A large number of various treatment materials effective against environmental pollution caused by oil have already been developed and put into practical use. Even looking only at products made of lipophilic synthetic resins, they are available in various shapes such as pulp, granules, lumps, strands, and mats. Among these, fillers for water treatment equipment (hereinafter referred to as
It is called overwood. ), pine-like materials have poor water permeability and are not preferred. In addition, pulp-like materials tend to form water channels (so-called "channel rings", hereinafter referred to as this term) and have poor oil absorption efficiency.To prevent this, if they are compressed and filled before use, the water permeability will decrease. It is difficult to use as overfill material for mass processing. From this point of view, granular or small-sized materials having a certain shape and size within a certain range are preferable as overmaterials intended for mass processing. Examples of such granules or small lumps that have been proposed include oil adsorbents cut into square pieces, extruded strands of lipophilic polymer cut into pellets, and lipophilic polymers extruded into strands and cut into pellets. Foam etc. cut into sawdust, sheets,
It is known that a film or fibrous material is placed in a crusher and crushed into an appropriate size. or,
In order to utilize the surface area of the fibrous material as much as possible,
It has been proposed to cut the fibers into short fibers and stir them in water to entangle them into a fluff-like shape. Combining these conventional findings and the inventors' studies,
The following structure is most suitable for a filter material having excellent water permeability as well as oil absorption, which is the object of the present invention. That is, first, in order to ensure a large overall surface area, mere lipophilic resins or crushed foams thereof are inappropriate, and it is effective to use fibers or fibrillated fibrous materials. Second, in order to ensure voids for water permeability, it is necessary that the material be in the form of granules or small lumps so that the apparent density at the time of filling falls within a certain range. One method is to wet-paper fibrillated fine fibers (so-called synthetic pulp) to form a nonwoven sheet, heat-treat it to fuse some of the fibers, and then It has been proposed to obtain granular oil adsorbents made of fibrillated fibers by cutting them into dice. (Unexamined Japanese Patent Publication 1973-
(1985) This adsorbent certainly improves water permeability when used as a filter material, but the practical throughput is at linear velocities ranging from several m/min to 20 to 30 m/min.
Mass processing at speeds of 50 m/min to 300 m/min is not possible. Another proposal is an amorphous granular oil adsorbent that uses fibrous material as a raw material and pulverizes it in a pulverizer, causing some of it to melt and become granular due to the frictional heat generated. (Jikko 47-
31075, Japanese Patent Application Publication No. 52-101683). The structure of this product is that there is a molten resin mass in the center and fibrous so-called whiskers on the sides, so it can achieve the desired performance. However, the granules made by this so-called melt granulation method are superior to the shredded nonwoven sheets mentioned above in that they have both oil absorption and water permeability, but on the other hand, they require the use of a pulverizer during production. However, the generation of particles with small particle sizes or fine powder is unavoidable, and it becomes necessary to sieve the fine powder for actual use, and there is a need to worry about secondary pollution due to dust. Furthermore, since the center portion of this structure is a molten mass, it does not have substantial oil absorption performance, and the oil absorption property is entirely dependent on the surrounding fibrous material. In this point,
The oil absorption per unit weight of the adsorbent is poor. Under these circumstances, the present inventors conducted intensive studies to obtain an oil adhering material that does not cause channeling during water flow treatment and has higher efficiency, and as a result, the present invention was completed. It is. The present invention is a granular material obtained by shredding a laminate of fibrillated net-like material made of a thermoplastic resin having lipophilic properties, and the shredded material is cut by using a shearing type cutting machine. As a result, the cut surface of the granules maintains the shape at the time of cutting without substantially peeling, and the apparent density of the aggregate of the granules is 0.05.
It is an object of the present invention to provide a granular oil adsorbent having excellent water permeability and oil absorption, characterized in that the water permeability is 0.10 g/cm ³ . The lipophilic synthetic resin in the present invention includes propylene polymers such as isotactic polypropylene, propylene-ethylene block copolymer, propylene-ethylene random copolymer,
For high-pressure polyethylene, medium-low pressure polyethylene, etc., one type of thermoplastic resin having substantially lipophilic properties such as polyethylenes, ethylene-vinyl acetate copolymers, polystyrene-based polymers, polyester-based polymers, etc., or a mixture thereof is used. The fibrillated net material used in the present invention is a fibrillated net obtained by extruding the above thermoplastic resin into a tape or film, stretching it, and mechanically defibrating it using a needle drum. The fibers used are those that are fibrillated into a net by ultrasonic impact, etc. without using a machine. Other suitable materials are obtained by mixing a lipophilic thermoplastic resin with a volatile compound such as Freon, pentane, or butane, or a so-called chemical blowing agent such as azodicarbonamide or sodium bicarbonate, and extruding the mixture using an extruder. There are fibrillated net-like products produced by the so-called foam defibration method. This material can be produced at low cost, has a high degree of fibrillation, and has a large surface area, making it convenient as an oil adsorbent. In any case, the fibers are connected like a net, and when this is shredded,
The structure is such that there are no single fibers falling out from each individual granule, and that fine fibers, so-called fibrils, are present, and that they are crimped on the cut surface by cutting with a knife, etc., and produce a relatively large peeling resistance. is important. In the present invention, entanglement between fibril fibers exists as a factor that causes a relatively large peeling resistance on the cut surface, which increases the crimped area and also maintains the substantial granular shape of the entanglement between fibril fibers. It is assumed that this is working effectively. The granular oil adsorbent of the present invention is produced by obtaining a laminate made by laminating a plurality of fibrillated net-like materials made of the above-mentioned thermoplastic resin, and cutting the laminate into appropriate sizes using a shear-type cutting machine. This can be obtained by At this time, the compression between the fibril fibers substantially prevents the laminate from peeling off at the cut surface, resulting in a granular material that maintains its shape when shredded. The oil-absorbing material according to the present invention has significantly improved oil-absorbing performance compared to a method in which the material is fused and cut using a heat cutter or the like. Regarding the dimensions of this shredded granule, the apparent density is 0.05 to 0.10 g/
There is no particular limitation as long as the size is cm ³ , and a wide range of sizes can be obtained by changing the number of laminated sheets, the rotation speed of the cutting machine, etc. Therefore, the number of laminated fibrillated net-like materials is not limited in the present invention. In general, granules obtained from a material with a small number of laminated sheets have excellent oil absorption properties, but are inferior in water permeability, so for ordinary oil-water mixtures, granules obtained from laminated materials with a thickness of 2 to 7 m/m are suitable. . In addition, as mentioned above, the dimensions are not particularly limited as long as they are not just pine-shaped, but for normal oil-water mixtures, a range of 2 m/m square to 20 m/m square is preferable, and for convenience in handling, 3 m/m square is preferred. A range of square to 7 m/m square is preferred. The cutting machine used to shred the laminate may be a guillotine cutter, shredder, or the like. However, when cutting, it is inappropriate to apply heat to a knife or use a high-frequency cutter, etc., because the effects of the present invention will not be achieved. In other words, the heated cut surface becomes a so-called heat-sealed state, which causes the fibril fibers to fuse together, which not only causes a decrease in oil absorption performance, but also
As will be described later, it becomes impossible to finely adjust the apparent density by loosening the fibrillar fibers of the granules by blender treatment or the like. The apparent density can also be adjusted by adjusting the sharpness of the knife during shredding and granulating the fibril fibers while keeping some of the entanglements, but this adjustment is actually difficult. First, it is preferable to obtain granules that are shredded so that the strength of the cut surface is constant as a whole. At this time, the peeling strength between the fibril fibers is 50~
Although it is preferable to use a cutting force of about 150 g/inch, this is not effective with a cutting machine such as a band saw, and is effective only with a shearing type cutting machine (for example, a shredder) used in the present invention. Furthermore, the granules obtained in this way are stirred in a blender to loosen and fluff some of the fibrillar fibers, and the apparent density is finely adjusted in the range of 0.05 to 0.10 g/cm ³ to improve oil absorption and water permeability. A well-balanced oil adsorbent can be obtained. In addition, in the case of mass production,
Even without using a mixer, the disentanglement can be effected by passing air through a piping system of an appropriate length using a blower and providing a stirring action. In the present invention, the definition of the apparent density of the granule aggregate is important. That is, the apparent density is 0.05
The value is less than 0.05 g/cm ³ when it is already less than 0.05 g/cm ³ before the fibril fibers on the cut surface are unraveled, and when the granules that have been formed are excessively disentangled and the amount is 0.05 g/cm 3 . There are cases where it is less than /cm ³ .
In any case, if it is less than 0.05 g/cm ³ , it actually becomes an aggregate that should be considered flake-like or cotton-like rather than granular, and if we only focus on its oil adsorption ability in a static water state, it is quite good. However, it has the disadvantage that it has no compression resistance and can easily channel. Furthermore, if the material is pre-compressed to prevent channeling, the water permeability will be significantly reduced. An apparent density of 0.05 g/cm ³ is specified as the lower limit at which such a situation does not occur. On the other hand, those with an apparent density exceeding 0.10g/ ^cm3 ,
The fibril fibers are insufficiently unentangled, and the so-called fluff portion lacks oil-absorbing performance, and oil easily escapes, resulting in channeling. The apparent density obtained in this way is 0.05g/cm ³ ~
The granular oil adsorbent of the present invention, which has a particle size of 0.10 g/cm ³ , does not have a drop in oil absorption performance due to thermal adhesion, unlike shredded heat-treated sheets or granular products produced by the melt granulation method, and substantially has a certain degree of regularity. Because it is in a granular form, it maintains high water permeability. In addition, it has extremely excellent features as an oil-absorbing overmaterial, such as no generation of fine powder during manufacture and use. However, the granular oil adsorbent according to the present invention is not only used as a filter material, but also can be used for stationary general oil treatment, such as spraying on floors where oil has leaked or spraying it into rivers. However, it is possible. The explanation will be supplemented by examples below. Example 1 Polypropylene homopolymer (Mitsui Noblen)
100 parts by weight of JHG) and 10 parts by weight of azodicarbonamide were foamed and extruded using an inflation die with a 0.5 mm slit, resulting in a basis weight of 6.5 g/m ²
The fibrillated net-like material of
Various granules as shown in No. 1, No. 2, and No. 3 in No. 1 were obtained. These various granules are placed in a 40mmφ acrylic tube.
A 30cm bed is filled, and an oil-water mixture containing 5000 ppm of B heavy oil is passed through this to measure the linear velocity of the liquid, the outflow of oil droplets on the outlet side, and the oil adsorption when the overfill material in the packed bed reaches saturation. The rate (amount) etc. were measured. All of these had excellent oil absorption and sufficient water permeability. Reference example Table-1 No.4 using the same raw materials as Example 1,
Granules as shown in No. 5, No. 6, and No. 7 were obtained. This material was unsuitable as an overfill material because channeling occurred and oil droplets fell immediately after the oil/water mixture was passed through.

[Table] Example 2 When extruding 100 parts by weight of polystyrene (Toporex 550), 1.0 parts by weight of Freon-11 was injected from the middle of the extruder, and the molten mixture was
The foam was extruded using an inflation die having a slit of 0.5 mm to obtain a fibrillated net-like product having a basis weight of 8.2 g/m ² . After stacking 80 sheets of this net-like material, it was shredded into 5 mm square pieces using a shredder. The apparent density of this product was 0.12 g/cm ³ . The granules were then disentangled using a drum blender for 5 minutes to obtain fluffy granules with an apparent density of 0.075 g/cm ³ . This product was overtested in the same manner as in Example 1. As a result, there was no channeling, and oil was removed without any problems until the saturated oil absorption amount reached 3.1 times (g/g). In addition, the initial linear velocity of liquid passing is
It was 210cm/min. Example 3 Polyethylene terephthalate (Gutdeyer Co., Ltd.)
VFR-5041) 100 parts by weight of azodicarbonamide
0.75 parts by weight and 0.5 parts by weight of sodium bicarbonate were blended and extruded, and 0.5 parts by weight of Freon-11 was injected from the middle of the extruder, and foaming was extruded using an inflation die with a 0.5 mm slit to reduce the basis weight.
A fibrillated net of 7.5 g/m ² was obtained.
After laminating 100 sheets of this net-like material, it was cut into 7 mm square pieces using a guillotine cutter. The apparent density of this product was 1.12 g/cm ³ . Next, the granules were passed through a PVC bellows pipe with a diameter of 150 mm and a length of 5 m using a blower, and discharged into a cloth bag, with an apparent density of 0.073.
A granular aggregate with fluff of g/cm ³ was obtained. The overtest results of this product are good, and the saturated adsorption amount
Oil content could be removed without channeling until it reached 2.8 times (g/g). In addition, the initial linear velocity of liquid passage was 230 cm/min. Example 4 Polypropylene homopolymer (Mitsui Noblen)
JHG) 55 parts and high-density polyethylene (Hi-Zex
1300J) 45 parts of the mixture was extruded through a T-die with a slit width of 0.6 mm, then uniaxially stretched 5 times in the extrusion direction to wind up a 15 μm film. This uniaxially stretched film was repeatedly subjected to defibration using a needle drum having a length of 7 mm to obtain a fibrillated net-like product weighing 13.5 g/m ² . 50 sheets of this net-like material were stacked and then shredded into 5 mm square pieces using a Schrader to give an apparent density of 0.105 g/
Granules of cm ³ were obtained. Mix this with a drum blender for 7
The fluffy granular aggregate with an apparent density of 0.065 g/cm ³ was obtained by processing for 1 minute. This product was successfully tested in the same manner as in Example 1, with no channeling and continued oil removal until the saturated oil adsorption amount reached 3.3 times (g/g). The initial linear velocity of liquid passage was 190 cm/min.

Claims (1)

[Scope of Claims] 1. A granular material obtained by shredding a laminate of fibrillated net-like material made of a thermoplastic resin having lipophilic properties, the shreds being cut by cutting using a shearing type cutter. By doing so, the cut surface of the granules maintains the shape at the time of cutting without substantially peeling, and the apparent density of the aggregate of the granules is 0.05 to 0.10 g/cm ³
A granular oil adsorbent with excellent water permeability and oil absorption. 2. The granular oil adsorbent according to claim 1, whose apparent density is adjusted to 0.05 to 0.10 g/cm ³ by disentangling the granules using a mixer or a pneumatic transport device.