JPS61257209A - Recovering method for dry cleaning solvent - Google Patents

Abstract

PURPOSE:To separate free water in dry cleaning solvent from the solvent with high efficiency and high accuracy by allowing the solvent to permeate a fibrous sheet having >=35dyne/cm critical surface tension. CONSTITUTION:Dry cleaning solvent contg. free water is recovered by distilling azeotropically the solvent, and the recovered solvent is allowed to permeate a fibrous sheet constituted mainly of single fiber having 0.1-10mum diameter having 10-70% packing rate. 0.1-70mm thickness, and >=35dyne/cm critical surface tension on the surface of the fiber. Thus, the water particles in the solvent having 0.1-50mum particle size form water drops having >=0.1mm particle size. When the permeate is transferred to a measuring cylinder, the coarse water drops having >=0.1mm particle size rise upward in the oil phase, forming immediately a transparent water phase and an oil phase.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is a method of highly accurate IC@collection of only the solvent by separating the solvent from the water droplets that are minutely dispersed as free water in the dry cleaning solvent after distillation. Regarding how to.

[Conventional technology]

Dry cleaning is a method of washing clothing using a solvent as a washing bath, as opposed to washing using water as a washing bath. When washing clothes using water as a washing bath, the quality of clothing and the like is subject to a drop in quality. For example, it swells when it absorbs water and shrinks when it dries, causing wrinkles and
Natural fibers that may change in size or lose their shape; wool fibers that have a scaly structure that shrinks when exposed to mechanical force in water; there is a risk that the texture, color, luster, appearance, etc. of the thin fabric may change or deteriorate. Wool, silk products, etc. that have a certain texture are subject to dry cleaning.

Dry cleaning machines typically have a tabular structure as shown in the schematic diagram of FIG. That is, laundry and a solvent (including an activator) are placed in a horizontally placed cylindrical rotating drum 1, and the rotating drum 1 is rotated for 10 to 30 minutes to wash the laundry. After washing, the solvent is removed and the laundry is heated and dried in the rotating drum 1 using steam or electricity as a heat source. All or part of the solvent contaminated by washing is put into a distiller 2 installed in the dry cleaning machine, distilled, cleaned, and used again.

On the other hand, textile products before dry cleaning contain moisture from the atmosphere, but during dry cleaning, the moisture in the textile products transfers to the solvent side, so in reality, solvent and water can mix into the distiller. become. If this product is distilled, free water on the order of P, P, and M will be mixed into the recovered solvent after distillation (due to azeotropy of the solvent and water).

Further, in the -1 distiller 2, sludge such as dirt and activator attached to the laundry is accumulated, so that the solvent remains in the sludge. For this reason, the solvent in the sludge is also recovered and reused by blowing steam directly into the distiller 2 once a day, but free water will also be mixed into the recovered solvent.

Textile products subjected to dry cleaning are highly likely to suffer from the problems described above if water is present, so in order to prevent free water from being mixed into the recovered solvent, the textile products are removed from the distiller 2 to the cooler. Currently, the recovered solvent that comes out through the tank 3 is separated into solvent and water by a specific gravity separator 4, and only the solvent is recovered in a clean tank 5 for reuse.

However, since the free water in the solvent that comes out through the cooler 3 exists in the form of minute water droplets that are usually less than 10 J4 m, it is not possible to separate the solvent and water sufficiently by specific gravity difference separation alone. Wool, silk products, etc. have had the problem of deterioration in quality due to free water contained in the recovered solvent.

As mentioned above, in order to separate the free water contained in the recovered solvent, some super absorbent fibers are used that have the ability to absorb water tens to hundreds of times their own weight. If the capacity is exceeded, it becomes impossible to separate free water, resulting in the problem that the superabsorbent fibers have to be replaced more frequently.

In addition, superabsorbent fibers that exceed their water absorption capacity also contain a dry cleaning solvent in addition to the water plate, and there is also the problem that post-treatment of the superabsorbent fibers after water absorption requires time and effort.

[Problem that the invention seeks to solve]

The purpose of the present invention is to overcome the above-mentioned conventional techniques and efficiently and efficiently remove the solvent and free water in order to prevent the deterioration of the quality of textile products due to the contamination of free water into the recovered dry cleaning solvent after distillation. It is an object of the present invention to provide a method for separating with high precision and continuously recovering only the solvent.

[Means for solving problems]

After distillation and before specific gravity separation, the present inventors made a fibrous sheet consisting of ultrafine fibers by passing through a solvent containing minute water droplets to coarsen the minute water droplets, and then continuously We have discovered that solvent and free water can be separated efficiently and with high precision by differential separation, and have arrived at the present invention.

In view of the above-mentioned problems, in the method of recovering dry cleaning solvent through a distillation process and a specific gravity separation process, the following process 1! The solution is to incorporate A(m)t- and continuously recover the dry cleaning solvent.

(a) A fibrous sheet mainly composed of fibers with a single fiber diameter of 0.1 to 10 μm, a fiber filling rate of 10 to 701, a thickness of 0.1 to 70 cm, and a critical surface tension of the fiber surface of 35 dyne/m or more. A process in which microscopic water droplets are made into coarse particles.

Examples of the dry cleaning solvent in the present invention include chlorinated solvents such as tetrachlorethylene, 1 e 1 ml-) dichlorethane, and carbon tetrachloride, trichlorotrifluoromethane, and chlorofluoromethane. Typical examples include thread solvents and petroleum-based solvents that are mixtures of hydrocarbon compounds such as n-decane, but are not limited to them. Includes solvents used.

"Distillation process" refers to a distillation device that includes a distiller that vaporizes the solvent using steam or electricity as a heat source, and a cooler that liquefies the vaporized solvent using water or other heat exchange medium. The capacity, shape, etc. of the container and cooler are not limited.

"Specific gravity separation process" is a process in which high-quality solvent +
The process of separating the free aqueous solution into the solvent and water based on the specific gravity difference between the solvent and A in the specific gravity difference separator is the capacity of the specific gravity difference separator,
Although the shape is not limited, it is a ratio 1 for a general dry cleaning machine.

The "coarse graining step" in the method of the present invention is 0.1 to 5
0. 0.1 sm or more C
This refers to the phenomenon of forming coarse water droplets, and the coarse droplets of 0.5 m or more are easily floated and separated due to the difference in specific gravity with the solvent.The second coarsening process is carried out between the distillation process and the specific gravity separation process. Although it is necessary, in equipment where two or more specific gravity difference separators are installed in the specific gravity difference separation process, it is possible to install it before the darkest specific gravity difference separator. The processing speed of these solvents is between that of distillation.

Furthermore, the coarsening step in the present invention involves making the fine water droplets in the solvent coarser within the fibrous sheet by passing a solvent in which fine water droplets are dispersed through a fibrous sheet to which electricity is distributed below. The following specific gravity difference separation takes a short time. It refers to the process to ensure that the The fibrous sheet used in the method of the present invention may be a woven fabric, a knitted fabric, or a nonwoven fabric. Although the fibers constituting the fibrous sheet are not limited, examples include polyethylene terephthalate and polyethylene terephthalate! Adipate, /IJ ethylene terephthalate inphthalate, polyethylene terephthalate separate, polyethylene terephthalate. Polyester copolymers such as phthalate/dodecanoate, polybutylene terephthalate, etc., fibers, polyamide, sameethylene azinamide, Ilihe, 1,000, methylene sepacamide, polyamide, sameethylene deca. Fibers of polyamides such as polyamide, polyhexamethylenehexamide, polycapramide, polyoctamide, polynonamide, polydecamide, polydodecamide, polytetramid, polyamide/imide fibers, aromatic polyamide fibers, polyno, polycybenzoate, etc. ? Liether ester fibers, polysalts: Halodane-containing polymer fibers such as vinyl chloride, polyvinylidene chloride, polyvinylidene fluoride, polytetrafluoroethylene, 4-lyolefin fibers such as -lipropylene and polyethylene, various acrylic fibers, and vinyl banners. Natural fibers include alcohol-based fibers, regenerated cellulose fibers, acetate, cotton, linen, silk, and wool. These fibers can be used alone or in combination.

The single fiber diameter of the fibers constituting the above fibrous sheet is 0.1
~10 μm is mainly used. Single fiber diameter is 1
If it exceeds 0 μmt, it will be difficult to capture and coalesce minute water droplets (5 μm or less) within the fibrous sheet, making it impossible to obtain sufficient grain coarsening performance.

Fibers smaller than 0.1'μm are difficult to produce uniformly in industry. Desirably, the single fiber diameter is 0.3 to 7 μm.
Mainly things. Here, "consisting mainly" means that the weight of the fibers having the above-mentioned single fiber diameter is 50 inches or more, preferably 70% or more of the total weight of the fibers constituting the fibrous sheet. means. For example, if the diameter of the fiber is uniform along its length, a fibrous sheet obtained by mixing fibers with different diameters may be obtained.

It is sufficient if the weight of the fibers having a diameter of 0.1 to 10 μm among the single fibers in the fibrous sheet is 50 modulus or more. If the weight of the single fibers having a diameter of 0.1 to 10 μm is less than 50% of the total weight of the fibers constituting the fibrous sheet, sufficient coarse graining performance cannot be obtained.

The fiber filling rate of the fibrous sheet is in the range of 10-70%. The "fiber filling rate" is defined by the following formula. When the fiber filling rate is less than 10, minute water droplets permeate through the fibrous sheet without being captured, so the coarsening performance is low, and the fiber filling rate increases due to the deformation of the fibrous sheet. However, the pressure loss changes greatly between the beginning and the end, which is not preferable. Moreover, if it exceeds 70 inches, the pressure loss is too large. A desirable range of fiber filling rate is 20 to 60%.

The thickness of the fibrous sheet is 0.1 wm or more and 70 wm or less, preferably 0.2 wm or more and 50 wm or less. When the thickness is less than 0.1 mm, a large proportion of minute water droplets pass through the fibrous sheet without being captured, and sufficient grain coarsening performance cannot be obtained. If it is 70 or more, the pressure loss during liquid permeation is too large.

1. The fibers constituting the fibrous sheet are those whose surface has a critical surface tension of 35 dyne/cm or more. The surface tension of water in the present invention is
If the critical surface tension of the fiber surface is less than 35 dyn・15+1, the water droplets will not wet the fiber surface, so the capillary action between the fibers alone will cause the water droplets to break and coalesce. Therefore, the water droplets are not sufficiently coarsened. The critical surface tension of the fiber surface is desirably 40 dyne/yIII or more.

The "critical surface tension" here is measured by the following method. The same material as the fibers forming the fibrous sheet.
A non-porous film was used as the measurement sample. In the case of fibers whose surfaces are coated or chemically bonded with various processing agents, first a non-porous film is made of the same material as the fibers9, and then the same processing agents are coated or chemically bonded to the fiber surfaces. The samples are processed under the same conditions and used as measurement samples. Critical surface tension is the surface tension when the contact angle is 020 degrees, so the contact angle of the above sample was measured with nine liquids having the exact surface tension, and by extrapolation, θ=O
The critical surface tension can be obtained by finding the surface tension at a certain degree.

K, which makes the fiber surface have a critical surface tension of 35 dyn/- or more, is made of a fiber material that has a critical surface tension of 35 dyn/- or more as the fibers constituting the fibrous sheet. Alternatively, the a#I surface may be modified with a resin or the like using a known method to improve the critical surface tension to 35 dyn@/m or more. Specific examples of fiber materials used in the former method include:
Polyvinyl alcohol fiber 1a(3)d)rne/m)
, polyethylene terephthalate fiber (43dyne/c
m ) s polyhexamethyleneazino matrix (46dy
ne/cIR), -vinyl chloride (39dyn@/c
f! M), regenerated cellulose and cotton (42dyne 7
cm) etc. are typical. Specific examples of the latter include hydroxyl group, cargexyl group, and amino group.

Hydrophilic functional groups such as ketone groups and sulfone groups are introduced into fiber polymers through chemical reactions, and hydrophilic compounds such as acrylic acid are added to the side by alkali treatment through graft polymerization. How to introduce it into the chain, polyethylene glycol, licalnic acid, polyisocyanate, vinyl group, glycidyl ether group, polyamine, N-
Examples include a method of making the fiber surface hydrophilic using a hydrophilic finishing agent such as a polyalkylene oxide containing methoxymethylol or the like, a polymer electrolyte, or a hydrophilic cellulose material. The compounds used to modify the fiber surface are not limited to the above-mentioned compounds, and in the method of the present invention, the critical surface tension of the fiber surface is 35 dyn・
Any material that can be modified to have a value of /- or more may be used.

The fibrous sheet in the present invention is not limited in any way to the liquid permeation method during grain coarsening treatment, and can be used in any form, such as a flat membrane, a cylinder, or a cylindrical shape. Furthermore, from the viewpoint of processing efficiency, it is preferable to use the fibrous sheet in a bellows-like form.
The liquid passing method may be any method such as liquid permeation by gravity or liquid permeation by pressure feeding, and is not limited to the above.

For the fibrous sheet used in the present invention, it is also possible to use a reinforcing material such as a wire mesh or a fibrous structure for the purpose of reinforcement. Further, in order to collect dust and the like in the processing liquid, it is also possible to place a dust-collecting material as a pre-filter before processing the liquid to be processed with the fibrous sheet. For example, the pre-filter may be a film-like or cotton-like dust-trapping material.

〔Effect of the invention〕

According to the method of the present invention, it is possible to efficiently, accurately and continuously separate free moisture that has conventionally been mixed into the recovered solvent, so textile products during dry cleaning can be easily separated due to the contamination of free moisture. Quality deterioration can be prevented.

Below margin 〔Example〕 Next, the implementation of the present invention will be specifically explained.

In the following examples, the critical surface tension of the surface of the fibers constituting the fibrous sheet was measured using a Kyowa Chemical Layer CA-D type contact angle measuring device. Moreover, the water concentration was measured by the following method.

Collect the sample to be measured in a 500WLl beaker, take 10ml of it, and add 0.21ml of ethanol with a known water content.
After adding R1, the moisture content was measured using the Karl Fischer method using MKC-3P (Kyoto Electronic Industry Exhibition).

The formula for calculating the water concentration is as follows.

C-D×106 Water concentration (ppl) −,. 1 A: Weight of 10 tJ of sample (Me B: Weight of 0.2 tJ of ethanol <ti> C: Amount of water in the entire sample + ethanol (N) D: Ethanol-NO, Z w
Moisture content in tl (li) Example 1 To form a fibrous sheet made of polyethylene terephthalate fibers with a single fiber diameter of 0.5 to 15.4 μm, the fiber filling rate was 221 and the thickness was 1.5 μm. That is, the single fiber diameter is 0.
A fibrous sheet consisting of fibers of 5 to 1.5 μm was obtained by melt blowing. Further, a fibrous sheet consisting of fibers of 3.7 to 15.4 μm was obtained by a wet papermaking method after cutting fibers obtained by direct spinning into a length of 5 m.

Six types of fibrous sheets with different single fiber diameters obtained in this way were attached to a filter holder manufactured by Milia (transmission surface diameter 90 mm), and the dry cleaner MC- It was installed between nine coolers and a specific gravity difference separator. In addition, in front of the filter holder, there is a liquid pump (
A phantom type manufactured by Nippon Feeder Co., Ltd.) was installed. 50 tons of tetrachlorethylene, an activator Gungu Clean PM250 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), and 3 tons of water were placed in the distiller of a dry cleaner machine, and distillation was carried out at a rate of 0.5 sty minutes.

After distillation and subsequent cooling, the solvent was a cloudy liquid with water droplets dispersed in tetrachlorethylene.

When we measured the water content in tetrachlorethylene, we found that
At 35°C, it was 250 p, p, m, and the size of the water droplet was photographically measured using an optical microscope, and it was 0.5. It was ~3 μm. Distillation - Cooled tetrachlorethylene is passed through a filter holder equipped with a fibrous sheet from a liquid feed pump at a rate of 0.5 t/ml, and then tetrachlorethylene and water are separated by specific gravity difference in a specific gravity difference separator. I went.

Table 1 shows the results of measuring the water content of six types of fibrous sheets with different single fiber diameters and tetrachlorethylene after specific gravity separation. Comparative Example (3) in Table 1 shows the water content when the sample was subjected to specific gravity separation immediately after distillation and cooling. As is clear from the results in Table 1, the method according to the present invention has an extremely good separation performance between the solvent and free water, and it can be seen that water is completely separated up to the level of solubility.

Below, when the permeated liquid after permeating the blank fibrous sheet was taken in a measuring cylinder and observed with the naked eye, it was found that the liquid obtained by the method of the present invention was 0.
It was found that water droplets coarsened to 5 to 2 square centimeters in size rose in the tetrachlorethylene, and immediately separated into two, a transparent tetrachlorethylene phase and an aqueous phase, due to the difference in specific gravity. On the other hand, the permeate of the comparative example was cloudy because fine water droplets were dispersed in tetrachlorethylene. It can be seen that in Comparative Example (3), there is almost no separation based on specific gravity difference.

Example 2 Fibrous sheets made of teripropylene fibers having single fiber diameters of 1.5 μm and 3.5 μm, respectively, were obtained by melt blowing. On the other hand, single fibers with diameters of 13.5 μm and 15.1 μm obtained by the direct spinning method were cut into 5 m pieces,
Fibrous sheets were formed by a wet papermaking method. After surface modification of these sheets under the following conditions, the thickness and fiber filling rate of the fibrous sheets were as shown in Table 2.

Table 2 Single fiber diameter Thickness Fiber filling rate 1.7
2.9 303.5 2.8
3013.5 3.0
3115.1 2.9 31 Modification conditions: After immersing the above fibrous sheet in a 4% aqueous solution of Permalos*TM manufactured by ICI, it was dehydrated and heated at 100°C
After drying for 3 minutes, heat treatment was performed at 170°C for 1 minute.Using the four types of fibrous sheets obtained in this way, tetrachlorethylene and water were separated using a treatment solution in the same manner as in Example 1. . The results are shown in Table 3.

The critical surface tension of the fiber surface after modification is 50 dyne/
It was more than cm.

As is clear from the results shown in Table 3 below, it can be seen that the method of the present invention can separate tetrachlorethylene and water with high precision.

Example 3 5. By direct spinning method. A nonwoven fabric having a fiber filling rate of 5% and a thickness of 0.2 m was obtained by a wet papermaking method after obtaining Oltm viscose rayon fiber and cutting it into 5 pieces.

Next, this nonwoven fabric is pressed to a fiber filling rate of 5 to 80.
A nonwoven fabric of 1 was obtained. Pressing process is 1-150kll/c
In addition to this, a nonwoven fabric was created in which the fiber filling rate varied depending on the pressing temperature and time.Next,
A fibrous sheet with a thickness of 10.0 ± 0.1 wm was created by overlapping several sheets of nonwoven fabric with the same fiber filling rate (critical surface tension of the fiber surface: 42 dyn/tan).
. The fibrous sheet thus obtained was attached to a 45 .phi. Millipore filter holder. Meanwhile, the following mixture was distilled and cooled at a rate of 127 minutes, and subsequently,
Using the same liquid feeding bond as in Example 1, the liquid was fed at a rate of 1 t/min to a filter holder equipped with a fibrous sheet, and the permeated liquid was then led to a specific gravity difference separator to perform specific gravity difference separation. . The results are shown in Table 4.

Mixed liquid nitrichloroethane 50t, water 2t Dry cleaning machine: Permac MC-9 (manufactured by Mitsubishi Heavy Industries, Ltd.) Distillation - Water content in trichloroethane after cooling is 510
The size of p, px, and minute water droplets was 0.5 to 3 μm as a result of photomicrograph measurements.

As is clear from the results in Table 4 in the margin below, it is clear that free water is not sufficiently separated in fibrous sheets with a fiber filling rate of less than 1 (a). Water is separated until solubility.

On the other hand, with a fibrous sheet of 70 inches or less, the pressure loss is 2.
On the other hand, in the case of SOW fibrous sheets, the pressure loss is extremely high and the industrial value is low.

Example 4 Nylon 66 fibers with a diameter of 5.0 μm obtained by the direct spinning method were cut into 5 m lengths, and then processed into sheets with a thickness of 0.05 cm and a fiber filling rate of 10 cm using the wet paper forming method. A nonwoven fabric was obtained. When this nonwoven fabric was treated under the following modification conditions,
The critical surface tension of the fiber surface was 5Qdyn@/w or more. This nonwoven fabric was tightly rolled up into a spiral shape to create a fibrous structure with a diameter of 45 mm and a height of 100 mm. The fiber filling rate of this product was 11%.

Modification conditions: The above fibrous sheet was immersed in a 4-polymer solution of Ranogun TNT-2 manufactured by Matsumoto Yushi Co., Ltd., deliquified, dried at 100°C for 3 minutes, and then heat-treated at 160°C for 30 seconds. Each spiral structure has a thickness of 50cm,
Three types of fibrous sheets 1 were prepared by slicing them into pieces of 705wm and 100mm.

On the other hand, a 0.05 m nonwoven fabric after surface modification was prepared.

Three types of fibrous sheets 1 were placed in a stainless steel container with a diameter of 45 m and equipped with an inlet and an outlet, and the container was installed so that the liquid was fed from the top of the cylindrical fibrous sheet 1 and the permeated liquid was obtained from the bottom. 203 types of fibrous sheets are 45! It was attached to a membrane filter holder manufactured by φNogu Repore.

The following mixture t1. Distillation-cooling 1 at a rate of o/Jl.
Then, using the same liquid feeding bond as in Example 1, the liquid was fed at a rate of 1.0/min to the filter holder equipped with the fibrous sheet, and the permeated liquid was then led to the specific gravity difference separator. Specific gravity separation was performed.

The results are shown in Table 5.

Mixed liquid nitrichlorotrifluoromethane 50! , water 2
1 The water content t in trichlorotrifluoromethane after distillation and cooling is 205 ppm-, and the size of the microscopic water droplets is 0.5 to 3 μm as a result of photomicrograph measurement, which is #l! 5
As is clear from the results in the table, the method according to the present invention has a low water concentration after separation based on the difference in specific gravity (separation is performed based on free water content), and is good, and is within the scope of the method of the present invention. It can be seen that the solvent and free water cannot be separated outdoors with low pressure drop.

Example 5 Single fiber diameter 1.7 μm, thickness 2 by melt blowing method
．． A fibrous sheet 3 of ethylene terephthalate with a fiber filling rate of 5 tm and a fiber filling rate of 28 tm was prepared. This fibrous sheet 3 is treated in the manner and under the conditions shown in the submanure, and the fibrous sheet 3 is treated with different critical surface tensions on the fiber surface (4), 5.
6 was created.

Fibrous sheet 4: Manufactured by Meisei Kagaku Co., Ltd., immersed in a 4 gb solution of Asahi Guard 800, dehydrated, dried at 100°C for 3 minutes, and then heat-treated at 18Q'c for 1 minute.

Fibrous sheet 5: polonM1 manufactured by FFL Etsu Silicon Co., Ltd.
After soaking in a mixed solution of 4 wt.
It was heat treated for several minutes. ' Fibrous sheet 6: Same treatment as Example 2 The above fibrous sheets) 3, 4, 5.6 were subjected to experiments using the same method and conditions as Example 1, and an experiment was conducted to separate tetrachlorethylene and free water. Ta'.

In addition, the fibrous sheet after surface modification is Fi#! It was Tooshi on the 6th table.

Table 6 Thickness Fiber filling rate Critical surface tension (xi) (%) (dyn-1 fibrous sheet 3 2.5 28 45#
42.8 26 16152.8
26 31x62.8 26
50 or more results are shown in Table 7.

As is clear from the above results, the method of the present invention can separate the solvent and free water with high accuracy. Those outside the scope of the method of the present invention cannot completely separate free water.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a dry cleaning machine. 1: Rotating drum, 2: distiller, 3: Cooler, 4: Specific gravity difference separator, 5: Clean tank, 6: Waoshi Otori Tank G...Rotating drum 2... distiller 3...Cooler 4...Specific gravity difference separator 5...Clean tank 6φ...Washta/ri July 30, 1985

Claims (1)

[Scope of Claims] A method for recovering a dry cleaning solvent through a distillation step and a specific gravity separation step, characterized in that the following step (a) is incorporated between the distillation step and the specific gravity separation step. Continuous solvent recovery method. (a) Mainly composed of fibers with a single fiber diameter of 0.1 to 10 μm,
A process of coarsening minute water droplets using a fibrous sheet having a fiber filling rate of 10 to 70%, a thickness of 0.1 to 70 mm, and a critical surface tension of the fiber surface of 35 dyne/cm or more.