JP2000018887A - Biologically decomposable sponge ball for cleaning pipe and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel biologically decomposable pipe cleaning sponge ball having sufficient strength, excellent in durability and cleaning characteristics and causing no environmental problem even if the sponge ball flows out from a system. SOLUTION: A biologically decomposable resin principally comprising cellulose acetate having thermal deformation temperature (ASTM D 648 regulation) of 44-55 deg.C under conditions where surface hardness (HR) is 80-100, impact strength is 15-30 kgf.cm/cm2 and load is 18.6 kgf/cm2 and acetylation rate of 45% is employed as a material and sponge balls are produced through water bubbling utilizing the vaporization expansion power of moisture.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sponge ball for a biodegradable washing pipe and a method for producing the same, and more particularly, to a heat exchanger which is currently a problem in nuclear power plants and thermal power plants. The present invention relates to a sponge ball for a biodegradable washing pipe for removing dirt such as scale and scale attached to an inner wall surface of a heat transfer pipe or a fluid pipe, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In a facility that generates electricity using a steam turbine such as a nuclear power plant or a thermal power plant, steam discharged from the steam turbine is cooled and condensed by a condenser.
They are collected as condensate water. The condenser is provided with a number of small tubes through which cooling water such as seawater passes, and heat is exchanged between the steam and the cooling water through the small tubes to condense the steam. When scale or the like adheres to the thin tube, the heat conductivity is reduced and efficient heat exchange cannot be performed.For this reason, sponge balls having a diameter slightly larger than the inner diameter of the thin tube, for example, about 25 mm in diameter, are mixed in the cooling water,
The inside of the condenser narrow tube is washed by the friction between the sponge ball and the thin tube to maintain the cleanliness of the cooling surface and to prevent a decrease in the heat exchange rate. The sponge balls in the cooling water that have washed the condenser tubes are usually collected by a ball collector provided on the cooling water outlet side of the condenser and returned to the cooling water inlet side for reuse. ing. However, the collection rate of sponge balls using a ball collector is about 95%.
Sponge balls that could not be recovered were flowing out to the sea through the spillway. For this reason, in recent years, the outflow of sponge balls into the sea has become a problem such as being taken up in newspapers. Various proposals have been made for such sponge balls, such as those having an abrasive attached to the surface. However, these conventional sponge balls have a recovery rate of less than 100%. If it leaks, it does not disassemble and remains indefinitely, which is a particularly environmental problem.

In addition, sponge balls have been made of sponge rubber to which natural rubber or synthetic rubber is added as a conventional material.
No. 80300 and JP-A-60-144600,
Japanese Patent Application Laid-Open No. 10-89889 discloses a biodegradable cleaning sponge comprising a foam in which a biodegradable low-melting fiber is mixed with a cellulose sponge. -A ball has been proposed. In the case of these cellulosic foams, the dispersion of the fibers to be compounded becomes nonuniform, the strength and the like vary, and there remains a problem in practical use. Also, Japanese Patent Application Laid-Open
According to JP-A-89889, cellulose sponge is
Alkaline treatment of plant fiber from wood, etc., then adding carbon disulfide etc. to make viscose, mixing crystals such as sodium sulfate with this viscose, and adding a blowing agent such as crystalline sodium sulfate to foam There has been proposed a method of manufacturing by solidification. Further, the conventional sponge ball has a spherical shape with a predetermined diameter and size. However, the conventional sponge ball has a large cleaning area as compared with the conventional sponge ball and provides effective cleaning. Japanese Patent Publication No. -101991 proposes that a large number of pieces of sponge rubber are bound at the center to form a ball. However,
Despite these proposals, there were still few biodegradable sponge balls for washing pipes that had sufficient biodegradability even if they flowed out of the system and had no environmental problems, and had strength and cleaning properties. . Therefore, it is biodegradable and strong enough,
There has been a strong demand for the development of sponge balls for washing tubes having good washing characteristics.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the conventional sponge / ball recovery system, to have a biodegradability that does not cause any environmental problems even if it flows out of the system. It is an object of the present invention to provide a novel biodegradable resin sponge ball made of a biodegradable resin foam mainly composed of cellulose acetate, which is excellent in durability and cleaning properties. Another object of the present invention is to provide a sponge ball for a biodegradable washing tube having a shape which can be effectively cleaned by using the biodegradable resin foam and which can be easily manufactured. . Still another object of the present invention is to provide a method for producing a sponge ball for a biodegradable washing pipe made of such a biodegradable resin foam.

[0005]

The inventor of the present invention has conducted intensive studies on the above-mentioned problems, and as a result, focused on the material and the manufacturing method of the sponge ball, and as a material of the sponge ball for washing pipes,
Using a biodegradable resin material containing cellulose acetate having specific physical properties as a main component, and a sponge ball for a biodegradable washing tube manufactured by a special foam manufacturing method,
It has been found that it is biodegradable and has sufficient durability and cleaning properties. The present invention has been completed based on these findings.

That is, according to the present invention, cellulose cellulose
Acetate, especially a surface hardness (H _R ) of 80 to 100, an impact strength of 15 to 30 kgf · cm / cm ² , and a load of 18.
Heat deformation temperature under the condition of 6 kgf / cm ² (ASTM D
648 standard) at 44-55 ° C and at least 45
A biodegradable resin containing cellulose acetate having a degree of acetylation of 0.1% as a main component, and is produced by water foaming utilizing the vaporizing and expanding power of water, and a sponge ball for a biodegradable washing tube. Is provided. According to the present invention, the biodegradable resin containing substantially moisture and cellulose acetate is charged into a cylindrical container having a narrowed opening in front, and the biodegradable resin is pushed into the narrowed opening. The temperature in the mold is heated and pressurized while the biodegradable resin is pushed into the mold, and the atmosphere is heated and pressurized while the biodegradable resin is pushed into the mold. After being pushed into the mold, the atmosphere inside the mold is rapidly reduced in pressure, thereby foaming the fluid biodegradable resin and molding it into a shape corresponding to the mold. And a method for producing the sponge ball for a biodegradable washing pipe. Furthermore, according to the present invention, a biodegradable resin containing substantially water and cellulose acetate is charged into a cylindrical container having an extrusion nozzle in the front,
During the pushing of the biodegradable resin to the extrusion nozzle, the temperature is raised to a fluidized heating and pressurized state, and then the rod-shaped extruded product of the fluidized biodegradable resin is extruded from the extrusion nozzle while the length thereof is changed. (L) / Diameter (D) Cut so that the ratio becomes 1 or a numerical value close thereto, and shape the foam after foaming into a spherical shape or a substantially spherical shape. A method is provided.

[0007] As described above, the present invention provides a novel biodegradable sponge ball for washing a flush tube using a biodegradable resin material containing cellulose acetate having specific physical properties and manufactured by a special foaming method. Although it relates to the production method, the preferred forms include the following.

(1) The biodegradable resin is further blended with at least one other biodegradable resin selected from the group consisting of cellulose, starch and polycaprolactone having a melting point not higher than the softening point of cellulose acetate. The sponge ball for a biodegradable washing pipe characterized by the above-mentioned. (2) The sponge ball for a biodegradable washing tube according to the above (1), wherein the other biodegradable resin is a polycaprolactone-based resin. (3) The sponge ball for a biodegradable washing tube, wherein a photocatalyst is further added to the biodegradable resin. (4) The sponge ball for a biodegradable washing pipe according to the above (3), wherein the photocatalyst is a titanium oxide. (5) 3 parts per 100 parts by weight of biodegradable resin
The sponge ball for a biodegradable flushing tube, further comprising a plasticizer in a proportion of 0 parts by weight or less. (6) The sponge ball for a biodegradable flushing tube according to the above (5), wherein the plasticizer is a polyhydric alcohol or a derivative thereof. (7) 1 part per 100 parts by weight of the biodegradable resin
The sponge ball for a biodegradable washing pipe, wherein a reinforcing fiber is further added in a proportion of 0 to 70 parts by weight. (8) The sponge for a biodegradable washing tube, wherein 6 to 16 triangular pyramids or triangular pyramids with truncated heads are uniformly cut over the entire surface of the ball. ·ball.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. 1. Biodegradable resin The biodegradable resin used in the sponge ball for a biodegradable washing pipe of the present invention contains cellulose acetate as a main component. The biodegradable resin that may be further blended as an accessory component is not particularly limited, and any one that is generally used as a biodegradable resin can be used. That is, as those corresponding to these, starch-based, cellulose-based, polycaprolactone-based, and the like, preferably, the softening point of the cellulose-acetate-based biodegradable resin, which is a main component from the viewpoint of moldability, etc. And a biodegradable resin having a melting point of, for example, polycaprolactone.

The cellulose-acetate-based biodegradable resin used as a main component is made mainly of linter obtained from cottonseed or cellulose acetate obtained by reacting acetic acid with cellulose of wood pulp. The cellulose acetate used in the sponge ball for a biodegradable washing tube of the present invention has a degree of acetic acid esterification of cellulose of 45% in terms of an acetylation degree represented by a ratio of acetic acid bound to cellulose. Those having the above conditions are preferred, and those having an acetylation degree of 47 to 60% are particularly preferred. If the degree of acetylation is less than 45%, the melting temperature is too high, so that it is difficult to stably melt-mold the foam. Also, in the physical properties of cellulose acetate,
It is preferably soft or medium hard, the surface hardness of Rockwell hardness, those H _R = 80 to 100, the impact strength 20
Those with 30 kg-cm / cm are preferably used. Furthermore, from the viewpoint of moldability, a heat deformation temperature of 44 to 55 ° C. under a load of 18.6 kgf / cm ² specified in ASTM D648 is preferably used.
On the other hand, with a hard material, it is difficult to stably melt-mold a foam.

[0011] Cellulose-acetate-based resins include cellulose acetate acetonate and cellulose acetobutyrate in which propionic acid or butyric acid is mixed and used, in addition to acetate having only an acetate group. The mixing ratio of the acid can be appropriately selected and used from the viewpoint of solubility in a solvent and the like.

[0012] Further, since the cellulose acetate resin has a chemical structure close to that of a natural product, it has a performance of decomposing by microorganisms in the environment, that is, a biodegradability. However, microorganisms that degrade it in nature,
That is, bacteria have a low density and, therefore, biodegradation occurs relatively slowly. However, it is possible to accelerate the decomposition rate by adjusting the material.
For example, when a photocatalyst is contained in a biodegradable resin, photodegradation occurs in a natural environment subjected to ultraviolet irradiation or the like, and in this case, the decomposition rate is further accelerated by both actions of biodegradation and photodecomposition. . Examples of the photocatalyst include titanium oxides, for example, titanium oxide ST series for photocatalyst and STS series manufactured by Ishihara Sangyo Co., Ltd.

[0013] The cellulose-acetate-based resin may contain other additives and the like as long as the object of the present invention is not impaired. Examples thereof include a heat stabilizer, a foam regulator and a foaming aid. . Among them, foaming regulators such as talc, silicon oxide, titanium oxide, magnesium oxide, aluminum oxide, inorganic fine particles such as calcium silicate, cellulose powder, chitin, chitosan, wood powder, organic fine particles such as metal stearate, In particular, talc can impart a suitable foaming property to the cellulose acetate resin, so that a uniform and highly foamed foam can be easily obtained. Such foam control agents may be used alone or in combination of two or more.

The amount of these foaming regulators and foaming assistants to be added to the cellulose-acetate resin is as follows.
A suitable range is 2 to 50% by weight, preferably 5 to 30% by weight, based on the acetate resin. If the amount is less than 2% by weight, the effect of adding these additives will not be exhibited. For example, if the amount of the foaming regulator is small, an uneven and coarse foam is likely to be formed, while if it exceeds 50% by weight, the secondary aggregation of these additives will occur. Is likely to occur, so that a non-uniform and coarse foam is likely to be formed, and the foaming property is also reduced due to a decrease in the fraction of the cellulose acetate resin.

The cellulose acetate resin used for the biodegradable sponge ball for washing pipes of the present invention can be used alone as a sponge ball for biodegradable washing pipes. The purpose of the invention,
That is, it has biodegradability, is sufficient in strength, and can contain reinforcing fibers within a range that does not impair the purpose of providing a sponge ball for a biodegradable washing tube having excellent durability and cleaning properties. . For this purpose, the reinforcing fibers must be at least biodegradable, and include, for example, synthetic fibers and natural fibers obtained by melt-spinning a biodegradable and heat-adhesive resin. Examples of such a resin include an aliphatic polyester resin, flax, and cotton. As the reinforcing fiber, a fiber having a fiber length of about 5 to 20 mm is preferably used in consideration of strength and dispersibility in a cellulose acetate resin. The content ratio of the reinforcing fiber is in the range of 10 to 70 parts by weight, preferably 10 to 50 parts by weight, based on 100 parts by weight of the biodegradable resin. If the content of the reinforcing fiber is too large, the dispersibility in the cellulose acetate resin is poor, and the sponge ball for a biodegradable washing pipe becomes too hard.

2. Biodegradable resin foam and method for producing the same The biodegradable resin foam used in the sponge ball for a biodegradable washing pipe of the present invention is constituted by a biodegradable resin containing cellulose acetate as a main component. , But further has the following features. Foamed with water. Biodegradable in all materials and plasticizers. It can deal with various disposal processes compared to general-purpose plastic foam. Compared to starch-based biodegradable resin foams, impact performance does not fluctuate due to atmospheric humidity, and strength is superior.

The most characteristic feature of the biodegradable resin foam is that it is produced by foaming with water. The method for producing a foam using water and the method for molding the obtained foam are as follows. And the following various methods. In the first method, substantially water and a biodegradable resin composed of a cellulose acetate resin are charged into a cylindrical container having a narrowed opening in front, and the biodegradable resin is pushed into the narrowed opening. The temperature inside the mold is kept in a pressurized state while the biodegradable resin is pushed into the mold while the temperature is raised to a fluid state. After it is pushed into the mold, the atmosphere in the mold is rapidly reduced in pressure, whereby the fluid biodegradable resin is foamed to have a shape corresponding to the mold. As a method of introducing substantially water and the biodegradable resin into the cylindrical container, a suitable amount of water may be contained in the biodegradable resin for foaming in advance, or water may be added together with the biodegradable resin. It may be added directly into the hopper, as long as the biodegradable resin and moisture are substantially supplied. In addition, the input ratio of water and a biodegradable resin composed of a cellulose acetate resin is 3 to 100 parts by weight of the biodegradable resin.
100 parts by weight are selected, preferably 5 to 50 parts by weight. Also, when a polyhydric alcohol or a derivative thereof as a plasticizer is added to a biodegradable resin composed of a cellulose / acetate resin, the boiling point of water in the biodegradable resin increases, so that the foam is dense and uniform. Become. Examples of polyhydric alcohols include polyethylene glycol, polymethylene glycol, glycerin, and the like, and glycols are particularly preferably used. In the first method of the present invention, these plasticizers such as polyhydric alcohols are appropriately added in an amount of 0 to 30 parts by weight based on 100 parts by weight of the biodegradable resin. Further, when a starch, for example, is added as a binder to a biodegradable resin composed of a cellulose-acetate resin, the foams are uniformly adhered to each other and the strength is increased. In the first method of the present invention, these binders such as starch are appropriately added in an amount of 0 to 30 parts by weight based on 100 parts by weight of the biodegradable resin. This first
In the method (1), the production of the foam and the molding of the foam can be performed in one step, so that the procedure is not complicated and is preferably used. In this method, a homogeneous foam having a desired shape can be obtained.

Next, as a second method, substantially water and a biodegradable resin containing cellulose acetate are charged into a cylindrical container having an extrusion nozzle in front thereof, and the biodegradable resin is poured into the extrusion nozzle. During the extrusion, the rod-shaped extrudate made of the flowable biodegradable resin is extruded from the extrusion nozzle while being heated to a heated and pressurized state. This is a method in which the foam is extruded from an extrusion nozzle into a spherical shape or a substantially spherical shape by cutting so that the ratio becomes 1 or a numerical value close to it. In this method, the biodegradable resin is discharged from the extrusion nozzle at a shear rate of 10 ^3.
After being extruded at ~ 2.0 × 10 ⁴ sec ⁻¹ , the extruded, biodegradable resin rod-like extrudate in a fluid state is immediately extruded with a knife or the like using a length (L) / diameter (D). The pellets are cut into appropriately sized pellets such that the ratio is at or near 1 and each cut pellet automatically becomes spherical or nearly spherical due to subsequent foaming. As a method of substantially adding the water and the biodegradable resin into the cylindrical container, similarly to the first method, an appropriate amount of water may be contained in the biodegradable resin for foaming in advance. Alternatively, water itself may be directly added into the hopper together with the biodegradable resin, and it is sufficient that substantially the biodegradable resin and water are supplied. The proportion of water to be added between the biodegradable resin composed of a cellulose acetate resin and water is 3 to 100 parts by weight, preferably 5 to 50 parts by weight, per 100 parts by weight of the biodegradable resin. Also, when a polyhydric alcohol or a derivative thereof as a plasticizer is added to a biodegradable resin composed of a cellulose / acetate resin, the boiling point of water in the biodegradable resin increases, so that the foam is dense and uniform. Become. Examples of polyhydric alcohols include polyethylene glycol, polymethylene glycol, glycerin, and the like, and glycols are particularly preferably used. In the second method of the present invention, these plasticizers such as polyhydric alcohols are appropriately added in an amount of 0 to 30 parts by weight based on 100 parts by weight of the biodegradable resin. . Further, when a starch, for example, is added as a binder to a biodegradable resin composed of a cellulose-acetate resin, the foams are uniformly adhered to each other and the strength is increased. In the second method of the present invention, these binders such as starch are appropriately added in an amount of 0 to 30 parts by weight based on 100 parts by weight of the biodegradable resin. This second
Is also preferably used because the procedure is not complicated since the production of the foam and the molding of the foam can be performed in one step. In this way, a homogeneous spherical foam suitable for a biodegradable sponge ball for a washing pipe can be obtained.

As a third method, a biodegradable resin and water are supplied to a kneading extruder at an appropriate ratio, and the mixture is heated at 120 ° C. to 250 ° C.
And then extruding through a die or nozzle having pores to obtain a foam of biodegradable resin, filling the obtained foam of biodegradable resin into a mold, A method comprising shaping and obtaining a molded article of a foam. The mixing ratio of the biodegradable resin and water is selected from 3 to 100 parts by weight of water, preferably 5 to 50 parts by weight, based on 100 parts by weight of the biodegradable resin. In addition, it is preferable to apply a plasticizer to the foam during the thermal shaping, and to thermoplastically fuse the surface of the foam to be used. The adhesion ratio of the plasticizer is 3 to 3 based on the weight of the foam.
It is appropriately selected within a range of 30% by weight. The plasticizer is not particularly limited as long as it can plasticize the biodegradable resin by heating.For example, when the biodegradable resin is a cellulose-acetate resin, various plasticizers such as polyethylene glycol and glycerin can be used. Dihydric alcohols; phthalic acid esters such as methyl phthalate; phosphate esters such as tributyl phosphate; dibasic acid esters such as dioctyl sebacate and dioctyl adipate; Further, it is preferable to increase the strength by attaching a binder to the foam during heat shaping so as to uniformly bond the foam to each other. The adhesion ratio of the binder is appropriately selected in the range of 0 to 30% by weight based on the weight of the foam. Examples of the binder include starch and the like.

3. Sponge ball for biodegradable washing pipe The sponge ball for biodegradable washing pipe of the present invention is used for removing dirt such as scale attached to the inner wall surface of the heat transfer tube of the heat exchanger. A spherical shape is usually used, and for example, a sponge ball for a biodegradable washing tube having a shape shown in FIG. 1 can be preferably used. In this method, 6 to 16 cuts are uniformly formed in the spherical biodegradable resin foam over the entire surface of the ball in order to increase the cleaning ability as compared with the conventional spherical one. In particular, triangular pyramids with 8 to 12 cuts are preferably used from the viewpoint of cleaning ability and production.

The size of the sponge ball for a biodegradable washing pipe of the present invention varies depending on the specific application, but is usually about 10 to about 10.
300 mm, for example, about 25 to 30 mm for a heat transfer tube of a heat exchanger, and about 3 to 30 mm for pig cleaning of a pipe.
A sponge ball having a diameter of about 0 to 300 mm is used. In each case, a sponge ball having the same diameter as or slightly larger than the diameter of the tube is used in order to clean the inside of the thin tube by a frictional force between the sponge ball and the thin tube. . Further, since the sponge ball for a biodegradable washing pipe is circulated and washed together with water or seawater, the specific gravity of the ball after absorbing water is preferably about 1 to 1.1. The specific gravity of the ball can be controlled by adjusting the foaming method.

In the cleaning method using sponge balls according to the present invention, for example, in the case of a heat exchanger, about 3,000 pieces per unit are usually put into a pipe. 1 to several pieces per shot.

The biodegradable sponge ball for washing pipes according to the present invention has improved mechanical properties, and its constituent materials are all biodegradable. Is finally decomposed into water and carbon dioxide, etc.
It is characterized in that the shape of the ball disappears.

The use of the sponge ball for biodegradable washing pipe of the present invention is not particularly limited, but specific examples thereof include heat transfer tubes for condensers of nuclear power plants and thermal power plants, and chemical plants. Scale cleaning of the inner wall surface of the heat transfer tube of the heat exchanger or scale cleaning of the inner wall surface of the pipe such as industrial water or seawater, for example, pig cleaning.

[0025]

The present invention will be described below in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples.

Example 1 Production of Sponge Ball and Biodegradability As a biodegradable resin, a soft cellulose diacetate manufactured by Teijin Limited (surface hardness (H _R ): 85, impact strength:
25 kgf · cm / cm ² , heat deformation temperature: 48 ° C., degree of acetylation: 57%) (standard: 100 parts by weight), water (31 parts by weight) as a foaming agent, and a plasticizer having an average molecular weight of 400 Polyethylene glycol (25 parts by weight), talc (13.6 parts by weight) was added as a foam regulator,
The third production method, that is, the mixture was supplied to a hopper of a melt-kneading extruder, heated and kneaded at a temperature of 180 ° C., and then extruded from a nozzle having a diameter of 1.5 mm to obtain a foam of a biodegradable resin. Then, the obtained foam of the biodegradable resin is filled in a mold and subjected to heat shaping to form a spherical sponge ball for washing a tube having a diameter of about 25 mm, and the obtained sponge ball is immersed in the sea. A degradability test was performed. The results are shown in Table 1 and FIG. The biodegradability test was carried out for six months by measuring the weight of the sponge ball before the test and the weight change every month and taking photographs. The sponge ball was 100% biodegraded and lost in the sea for 6 months.

[0027]

[Table 1]

Comparative Example 1 As a biodegradable resin, a thermoplastic biodegradable resin pellet comprising a derivative derived from a plurality of agricultural products such as starch and modified polyvinyl alcohol was used in place of the cellulose acetate resin. This resin is a resin derived from multiple agricultural products such as starch and denatured polyvinyl alcohol that penetrate each other at the molecular level into the partner molecule and are linked by hydrogen bonds, and usually absorb water and swell. It promotes biodegradation and exhibits biodegradability equivalent to that of paper in an environment where microorganisms can survive. A biodegradability test was conducted by obtaining a biodegradable foam and a spherical sponge ball for washing a tube, and immersing the same in the sea, in the same manner as in Example 1 except that the biodegradable resin was changed. The results are shown in Table 1 and FIG. The sponge balls degraded about 40% in the sea in 2 months and about 45% in 6 months.

Examples 2 to 5 [Photocatalyst] In Examples 2 and 3, in addition to the composition of Example 1, a powdery titanium oxide photocatalyst A (ST-01 manufactured by Ishihara Techno Co., Ltd .;
(X-ray particle size = 7 nm) was added in an amount of 0.5 part by weight or 1.0 part by weight, respectively, and a biodegradable foam was obtained in the same manner as in Example 1. On the other hand, in Examples 4 and 5, instead of the powdered titanium oxide photocatalyst A of Examples 2 and 3, a titanium oxide photocatalyst aqueous dispersion B (STS-01 manufactured by Ishihara Techno Co., Ltd .; titanium oxide concentration 30% by weight, X-ray particle size = 7 nm)
0.5 parts by weight or 1.0 parts by weight were added as titanium oxide components, and a biodegradable foam was obtained in the same manner as in Examples 1 to 3. A rectangular sample of 7 cm in length was cut out from these foams and subjected to a decomposition test by irradiation with ultraviolet rays. As a blank test, a 7-cm square sample was cut out from the foam of Example 1 and subjected to a decomposition test by ultraviolet irradiation. Irradiation with ultraviolet light was performed for 2 months with black light of a light amount of 1.8 mW / cm ² , and the change with time of the weight was measured to calculate the reduction rate.
The results are shown in Table 1 and FIG. The effect of adding the photocatalyst is clear.

Example 6 [Cleaning of heat exchanger tubes in heat exchanger] The spherical sponge balls for washing tubes having a diameter of about 25 mm of Example 1 and the foam of the biodegradable resin obtained in Example 1 were placed in a mold. Filled and thermally shaped, about 25 m in diameter with 8 cuts in the shape of a triangular pyramid with the shape shown in FIG. 1
50 m of sponge balls for tube washing were prepared. About these two types of sponge balls for washing pipes,
With a ball circulation pump, sponge for washing
After pumping the balls into separate heat exchangers at 2-3 kg / cm ² , the sponge balls for washing pipes pass through the heat transfer tubes,
The scale on the inner wall was scraped off and recovered. The cleaning ability of the two types of sponge balls was confirmed by visually evaluating the degree of cleaning of the heat transfer tubes. The cleaning ability of the spherical sponge ball for washing pipes of Example 1 was reasonably good. However, the sponge ball having eight cuts in the shape of a triangular cone was clearly cleaned compared to the spherical one. The result is increased ability. The sponge balls recovered were not deformed and could be reused.

Example 7 [Production of Sponge Ball] In Example 7, a sponge ball was produced with the same composition as that of Example 1 by applying the first production method. That is,
Forward restrictive opening (opening diameter: 3.5 mm) into a cylindrical container having, as a biodegradable resin, soft Teijin Co. cellulose diacetate (surface hardness (H _R): 85, impact strength: 25 kgf・ Cm / cm ² , heat deformation temperature: 48
° C, degree of acetylation: 57%) (reference: 100 parts by weight)
Water (31 parts by weight) was added as a foaming agent, polyethylene glycol (25 parts by weight) having an average molecular weight of 400 was added as a plasticizer, and talc (13.6 parts by weight) was added as a foaming regulator. The temperature is raised to about 180 ° C. while the biodegradable resin is pushed into the constriction opening, and is pushed into a gas-permeable spherical mold as a fluid, and while the biodegradable resin is pushed into the mold, the inside of the mold is changed. leave the atmosphere and pressurized state (about 5 kg / cm ² gauge pressure), after pushing the biodegradable resin into the forming mold is abruptly reducing the pressure of an ambient in the mold (atmospheric pressure), thereby fluidized Was foamed to obtain a spherical sponge ball for washing a tube having a diameter of about 25 mm. The obtained sponge balls had almost the same moldability as the spherical sponge balls for tube washing obtained in Example 1.

Example 8 [Production of Sponge Ball] In Example 8, a sponge ball was produced with the same composition as in Example 1 by applying the second production method. That is,
Extrusion nozzle (nozzle diameter: 4.5 mm) forward in the cylindrical container having, as a biodegradable resin, soft Teijin Co. cellulose diacetate (surface hardness (H _R): 8
5. Impact strength: 25 kgf · cm / cm ² , heat distortion temperature: 48 ° C., degree of acetylation: 57% (standard: 100 parts by weight)
And water (31 parts by weight) as a foaming agent, and polyethylene glycol (2) having an average molecular weight of 400 as a plasticizer.
5 parts by weight), and a foam control agent to which talc (13.6 parts by weight) is added, and while the biodegradable resin is being pushed to the extrusion nozzle, the temperature is raised to about 180 ° C. to obtain a fluid state. Pressurized state (approximately 5 kg / cm ² gauge pressure), and then a shear rate of 1.0 × 10 ⁴ sec.
Extruded at ^{-1, and} before the expansion due to water foaming occurs, the biodegradable resin rod-shaped extrudate still in a fluid state has a length (L) /
Cutting was performed so that the diameter (D) ratio became 1, and a substantially spherical sponge ball for washing washes having a diameter of about 25 mm was obtained by foaming generated thereafter. The resulting sponge balls had almost the same moldability as the spherical sponge balls for tube washing obtained in Examples 1 and 7.

From these evaluation results, the foam of the cellulose-acetate-based resin was compared with the foam of the biodegradable derivative-based resin obtained from a plurality of agricultural products such as starch.
Obviously excellent biodegradability. Further, the effect of adding the titanium oxide photocatalyst to the foam of the cellulose-acetate-based resin is also evident with respect to the UV decomposition performance. further,
A sponge ball of a cellulose acetate resin foam has excellent detergency in a heat transfer tube, and a sponge ball having a triangular pyramid-shaped notch has a better detergency than a spherical one. Furthermore, it became clear that the first and second production methods, in which foam production and foam molding can be performed in one step, are also excellent in moldability.

[0034]

According to the present invention, the sponge ball for a biodegradable washing pipe of the present invention is produced by a special foam production method using a cellulose acetate resin as a main component as a biodegradable resin and using water. Excellent biodegradability compared to biodegradable resins, and those containing a photocatalyst,
It has the effect of improving the decomposition ability. Further, the sponge ball for a biodegradable washing pipe of the present invention is excellent in the washing power in the heat transfer tube, and the sponge ball having a triangular pyramid-shaped cut is more excellent in washing ability than the spherical one. ing. The sponge balls for biodegradable washing pipes of the present invention can be used for scale cleaning of heat transfer tubes of condensers of nuclear power plants and thermal power plants, heat transfer tube inner walls of heat exchangers of chemical plants and the like, or other industrial water, It can be suitably used for scale cleaning of the inner wall surface of piping such as seawater, for example, pig cleaning.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a sponge ball for a biodegradable washing pipe according to an embodiment of the present invention.

FIG. 2 is a diagram showing the results of a biodegradability test of an example of the present invention.

FIG. 3 is a view showing a result of an ultraviolet ray decomposability test of an example of the present invention.

Continued on the front page F-term (reference) 4F074 AA02 AA03 AA68 AA76 AC17 AG02 BA34 BC12 CA22 CA23 CC04X CC04Y CC34X CC34Y DA08 DA09 DA24 DA59 4F204 AA01 AA24 AA32 AB02 AB17 AG20 AH81 EA01 EB01 EF01 EF02 EL02 EB23 AB02 AG02 EB02

Claims (9)

[Claims] 1. A sponge ball for a biodegradable washing tube, wherein the sponge ball is made of a biodegradable resin containing cellulose acetate as a main component and is produced by water foaming utilizing the vaporizing and expanding power of water. 2. The cellulose acetate has a surface hardness (H
_R ) is 80-100 and the impact strength is 15-30kgf ・ c
The heat distortion temperature (ASTM D648 standard) under the conditions of m / cm ² and load 18.6 kgf / cm ² is 44 to 55 ° C.
2. The sponge ball for a biodegradable washing tube according to claim 1, wherein the sponge ball has a degree of acetylation of at least 45%. 3. The biodegradable resin is further blended with at least one other biodegradable resin selected from the group consisting of cellulose, starch and polycaprolactone, having a melting point equal to or lower than the softening point of cellulose acetate. The sponge ball for a biodegradable washing tube according to any one of claims 1 to 2, characterized in that: 4. The sponge ball according to claim 3, wherein the biodegradable resin having a melting point not higher than the softening point of cellulose acetate is a polycaprolactone-based resin. 5. The sponge ball for a biodegradable washing tube according to claim 1, wherein a photocatalyst is blended with the biodegradable resin. 6. The sponge ball for a biodegradable flushing tube according to claim 5, wherein the photocatalyst is a titanium oxide. 7. A ball as claimed in claim 1, wherein 6 to 16 cone-shaped or truncated cone-shaped cuts are formed uniformly over the entire surface of the ball. A sponge ball for a biodegradable washing tube according to the above-mentioned. 8. A biodegradable resin containing substantially water and cellulose acetate is charged into a cylindrical container having a narrowed opening in front, and the temperature is raised while the biodegradable resin is pushed into the narrowed opening. During the process, the biodegradable resin is pressed into the air-permeable mold and the biodegradable resin is pressed into the mold. 2. The method according to claim 1, wherein after being pushed into the mold, the atmosphere in the mold is rapidly decompressed, whereby the fluid biodegradable resin is foamed and formed into a shape corresponding to the mold.
8. The method for producing a sponge ball for a biodegradable washing pipe according to any one of claims 1 to 7. 9. A substantially biodegradable resin containing water and cellulose acetate is charged into a cylindrical container having an extrusion nozzle at the front thereof, and while the biodegradable resin is pushed to the extrusion nozzle, the biodegradable resin is raised. The rod-shaped extrudate made of a fluid biodegradable resin is heated to a fluidized heating and pressurized state, and then extruded from the extrusion nozzle, with a length (L) / diameter (D) ratio of 1
8. The method for producing a sponge ball for biodegradable flushing tubes according to claim 1, wherein the sponge ball for a biodegradable washing tube is cut into a numerical value close to the numerical value, and the shape after foaming is formed into a spherical shape or a substantially spherical shape. .