JPH1017375A - Thermal expansion graphite composite molded article, method for producing the same, and oil absorbing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a lightweight, easily handleable porous composite formed body by depositing thermally expanded graphite on the inside of an interlocked matrix in which staples are fused to each other at their intersection points. SOLUTION: In this production, a mixture of thermally expanded graphite and thermoplastic resin based staples is charged into a mold and then, subjected to press forming while heating them to a temp. equal to or higher than the temp. at which the staples are fused to each other. Accordingly, the thermally expanded graphite is deposited on the inside of an interlocked matrix in which the staples are fused to each other at their intersection points, to produce the objective composite formed body. This composite formed body is lightweight and easily handleable and also has excellent absorbency and therefore, is useful as an oil absorbent material. As the thermally expansible graphite for forming the thermally expanded graphite, e.g. a graphite material obtained by subjecting natural scaly graphite that occurs in Canada and has 36 to 80mesh grain size, a 90wt.% fixed carbon content and a 8wt.% ash content, to acid treatment, thereafter, washing this treated graphite with water and then, drying the washed graphite, is used. The obtained thermally expansible graphite is heated to 1,000 deg.C to form thermally expanded graphite having a 0.004g/cc bulk density. The resulting thermally expanded graphite is mixed with PE(polyethylene) staples to obtain a mixture used as the above mixture.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermally expanded graphite composite molded article, a method for producing the same, and an oil absorbing material.
More specifically, the present invention relates to a porous, thermally expanded graphite composite molded article that is lightweight and easy to handle, a method for producing the same, and an oil absorbing material.

[0002]

2. Description of the Related Art The problem of large-scale marine pollution caused by oil spills caused by a large ship marine accident and an accident at a marine crude oil production base is as follows.
In addition to coastal fisheries, it also has direct damage to aquaculture fisheries such as laver, oysters and hamachi, and has a significant effect on natural biological systems.

Conventionally, for the above-mentioned marine pollution, a method of surrounding the spilled oil by an oil fence and pumping up and recovering it by a pump has been adopted, and various oil fences and recovery methods have been proposed. However, since the recovery of spilled oil is not complete, methods of using oil collecting materials or spraying a dispersant to neutralize the oil have been proposed. As oil collecting materials, inorganic and organic materials are used. Granules and the like have been proposed.

[0004] However, these oil collecting materials have problems that they are inconvenient to handle, difficult to recover after oil absorption, and that the oil absorption is not sufficient. On the other hand, in the dispersant, there is a fear that the dispersant itself floats in the sea or precipitates on the seabed, causing new damages that adversely affect plants and the environment.

[0005] The present inventors have previously proposed a method of using thermally expanded graphite as an oil absorbing material in order to efficiently recover oil spills (for example, Japanese Patent Application Laid-Open No. Hei 4-22403). . The heat-expanded graphite absorbs oil very well and is very easy to recover because it agglomerates after absorbing oil. The above method is an excellent method for treating oil-contaminated water.

[0006]

However, since the thermal expansion graphite itself is a bulky and extremely light powder,
In treating oil contaminated water, a problem was found that handling was difficult. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a porous thermally expanded graphite composite molded article that is lightweight and easy to handle. Another object of the present invention is to provide a method for producing the above-mentioned thermally expanded graphite composite molded article, and still another object of the present invention is to provide an oil absorbing material comprising the above-mentioned thermally expanded graphite composite molded article. .

[0007]

That is, the first aspect of the present invention is as follows.
The gist of the present invention resides in a thermally expandable graphite composite molded article characterized in that the heat expansion graphite is supported in an entangled matrix in which the intersections of short fibers are fused. A method for producing a thermally expanded graphite composite molded article, characterized in that a mixture with a thermoplastic resin-based short fiber is filled in a mold, pressed, and heated to a temperature at which the short fibers are fused to each other. A third aspect of the present invention resides in an oil absorbing material comprising the above-mentioned thermally expanded graphite composite molded body.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
First, for convenience of explanation, a method for producing the thermally expanded graphite composite molded article (hereinafter, abbreviated as composite molded article) of the present invention will be described.

[0009] The thermally expandable graphite used in the present invention refers to graphite obtained by thermally expanding thermally expandable graphite,
The above-mentioned thermally expandable graphite refers to a thermally expandable graphite obtained by oxidizing raw graphite such as natural graphite, pyrolytic graphite, and quiche graphite in the presence of a strong acid, washing with water, and drying. Then, after the raw graphite is treated with a mixture of sulfuric acid and an oxidizing agent, it is washed with water and dried, and thus the thermally expandable graphite can be easily obtained because it is already industrially used.

The above-mentioned heat-expandable graphite is obtained, for example, by pulverizing raw graphite to about 20 to 150 mesh and then mixing it with a mixture of 98% concentrated sulfuric acid and 60% hydrogen peroxide under a temperature condition of 45 ° C. or less. It can be manufactured by contacting for 30 minutes, followed by washing with water and drying.

[0011] The heat-expandable graphite has the property of expanding tens to hundreds times in the C-axis direction of the graphite crystal when rapidly heated to about 500 ° C or more. The heat-expandable graphite used in the present invention is preferably a heat-expandable graphite having a degree of expansion of about 2.5 to 1000 cc / g when rapidly heated at 1000 ° C. for 10 seconds. The bulk density after thermal expansion (bulk density of thermally expanded graphite) is usually 0.001 to 0.001.
0.4 g / cc, preferably 0.002 to 0.2 g / c
c.

The above-mentioned degree of expansion is determined by heating the sample in an electric furnace maintained at 1000 ° C. for more than 10 minutes.
cc quartz beaker was taken out of the furnace. Immediately, 0.5 g of the heat-expandable graphite was put into the beaker, immediately put into an electric furnace maintained at 1000 ° C., and left as it was for 10 seconds. And then the volume / weight ratio (cc / g) of the thermally expanded graphite after natural cooling.

The thermoplastic resin short fibers (hereinafter, abbreviated as short fibers) used in the present invention include, for example,
Short fibers such as acetate, polyamide, polyvinylidene chloride, polyurethane, polyester, polyethylene, and polypropylene are exemplified. The fiber length need only be long enough to form a network between fibers that gives the composite molded article the necessary strength after fusion at the intersection of short fibers. The above-mentioned fibers may be used by mixing different kinds of fibers, but from the viewpoint of achieving sufficient fusion between the fibers, a combination of materials having a small difference in melting point is preferable.

Specifically, the fiber length is usually from 10 μm to 2 μm.
0 mm, preferably 20 μm to 10 mm. When the fiber length is less than 10 μm, a net which gives the composite molded article a certain strength is not formed, and the fiber length is 2 μm.
If it exceeds 0 mm, uniform mixing of short fibers becomes difficult. Fiber diameter is usually 1 to 200 μm, preferably 5 to 100 μm
Is selected from the range. If the fiber diameter is less than 1 μm, a net which gives the composite molded article a certain degree of strength cannot be obtained, and if the fiber diameter exceeds 200 μm, it becomes difficult to uniformly mix the thermally expanded graphite and short fibers.

The method for producing a composite molded article according to the present invention comprises a first step of mixing thermally expanded graphite and short fibers, a second step of pressing and molding the mixture, and a third step of heating the pressed molded article.
Process. Hereinafter, each of these steps will be sequentially described.

<First Step> The first step is a step of mixing thermally expanded graphite and short fibers. The content of the short fibers is usually 5 to 80 by weight ratio to the total of the thermally expanded graphite and the short fibers.
% By weight, preferably in the range of 10 to 75% by weight. If the content of the short fibers is less than 5% by weight, the strength of the composite molded article may be insufficient and the mold may be lost.

On the other hand, if the content of the short fibers exceeds 80% by weight, the molten resin may enter the pores of the thermally expanded graphite, so that the porosity of the composite molded article may be lost. The mixing method is not particularly limited, but may be any method as long as the thermal expansion graphite is not remarkably broken in this step.

<Second Step> In the second step, the mixture obtained in the first step is filled in a desired mold, and the mixture is pressed and formed into a volume of 1/2 to 1/5 of the original volume. This is the step of obtaining a product. When pressing to a volume less than 1/2 of the original volume, there is a possibility that the strength of the pressed molded product is insufficient and the mold collapses. When pressing to a volume exceeding 1/5 of the original volume, the porosity of the pressed molded product may be lost. The shape and size of the pressed product may be appropriately adopted. Examples of the shape of the pressed product include a rectangular parallelepiped, a sphere, a sheet, and a block.

<Third Step> The third step is a step of heating the press-formed product obtained in the second step and fusing short fibers together. The heating temperature may be a temperature sufficient to fuse the short fibers together, and is equal to or higher than the temperature at which the short fibers fuse. Examples of the heating method include oven heating and Joule heating in which a pressed product is sandwiched between electrodes and a current is passed. Note that the above-described second step and third step do not necessarily need to be performed as separate steps, and heating may be performed simultaneously with press molding.

Next, the composite molded article of the present invention will be described. The composite molded article of the present invention is obtained by the above-described production method, and is characterized in that thermally expanded graphite is supported in an entangled matrix in which intersections of short fibers are fused. FIGS. 1 and 2 are photographs as substitutes for drawings of the cross section of the composite molded article of the present invention obtained in Examples described later, and have magnifications of 95 times (FIG. 1) and 85.
This is based on a scanning electron micrograph at a magnification of (FIG. 2).
FIG. 1 relates to a composite molded article using polyethylene as the short fiber, and FIG. 2 relates to a composite molded article using polypropylene as the short fiber. As is clear from these figures, it is understood that the intersections of the short fibers are fused.

As shown in the above figures, the composite molded article of the present invention has an entangled matrix structure in which the intersections of short fibers are fused, and thermally expanded graphite is supported in the matrix structure. It has a structure. The type of the short fibers constituting the matrix structure, the fiber diameter, the fiber length, the characteristics of the above-mentioned thermally expanded graphite, the quantity relationship between the short fibers and the thermally expanded graphite, and the like are as described above.

In the present invention, as one of preferred embodiments, a liquid-sheet surrounding composite molded article is included. The above-mentioned liquid-permeable sheet has a structure such as a mesh and a net made of fibers such as polyamide, polyester, polyethylene, polypropylene, and cellulose, a woven fabric, and a nonwoven fabric. The above fibers may be used by mixing fibers having different types, fiber lengths or fiber diameters. When different types of fibers are used in combination, a combination of materials having a small difference in melting point is preferable from the viewpoint of achieving sufficient fusion between the fibers. Further, the above-mentioned liquid-passing sheet is a mesh and a net made of metal, ceramics fiber or wire,
It may be a woven fabric, a nonwoven fabric, or the like.

The above-mentioned liquid-passing sheet surrounding composite molded article is produced by, in the above-mentioned steps, in the second step, surrounding the mixture obtained in the first step with the liquid-sheet and filling it into a mold. I can do it. On the contact surface between the composite molded article and the liquid-passing sheet, the short fibers in the composite molded article and the constituent fibers of the liquid-passing sheet may be completely or partially fused. The latter is preferred. From the viewpoint of maintaining the shape of the liquid-passing sheet, fibers having a higher melting point than the short fibers are usually selected as the fibers of the liquid-passing sheet. A combination of no fibers is preferred.

Further, in the present invention, by surrounding the composite molded article of the present invention obtained in the third step with the above-mentioned liquid-permeable sheet, it is also possible to produce a liquid-sheet surrounded composite molded article. .

Next, the oil absorbing material of the present invention will be described.
The oil absorbing material of the present invention is composed of the above-mentioned composite molded body.
The oil absorbing material of the present invention preferably contains an emulsion breaker. Examples of the emulsion breaker include sodium chloride, sodium carbonate, potassium chloride, calcium carbonate and the like. The composite molded article containing an emulsion breaker can be produced by blending the above-mentioned emulsion breaker with the mixture of the thermal expansion graphite and the short fibers in the first step.

The oil-absorbing material of the present invention has features such as high-speed oil absorption, high oil absorption, harmlessness to living organisms, and floating. Usually, the oil-absorbing material of the present invention is used by being introduced into an oil-contaminated water area, and can be recovered extremely easily. The oil-absorbing material of the present invention comprising a liquid-pervious sheet-surrounding composite molded article has a feature that, when swollen with oil-contaminated water, the thermal expansion graphite is particularly small and therefore there is almost no risk of contaminating seawater. .

The above-mentioned composite molded article of the present invention can be used in addition to the above oil absorbing material, electromagnetic wave shielding material, heat radiating material, vibration damping material, soundproofing material, shock absorbing material, heat generating material, antistatic material, wall material and the like. Is available.

[0028]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which, however, are not intended to limit the scope of the invention.

Examples 1 to 7 The heat-expandable graphite was acid-treated from natural flaky graphite produced in Canada having a particle size of 36 to 80 mesh, a fixed carbon content of 90% by weight, and an ash content of 8% by weight, followed by washing with water and drying. Used. As the heat-expandable graphite, heat-expandable graphite having a bulk density of 0.004 g / cc obtained by heating the above-mentioned heat-expandable graphite to 1000 ° C. was used.

The above-mentioned thermally expanded graphite and polyethylene short fiber (
"Kemibest FD990" manufactured by Mitsui Petrochemical Co., Ltd., fiber length:
2. 2 mm, fiber diameter: about 10-100 μm) or polypropylene short fiber (“RP852” manufactured by Chisso Polypropylene)
(Fiber length: 3 mm, fiber diameter: 22 μm) were uniformly mixed at the ratios shown in Table 1. Next, after filling the above mixture into a mold of 115 × 85 × 50 mm, it was subjected to a heat treatment under the conditions shown in Table 1 to obtain a pressed molded product of 115 × 85 × 10 mm.

The above heat treatment is carried out in an oven at 140 ° C. for polyethylene short fibers, 165 ° C. for polypropylene short fibers, and for a mixture of polyethylene and polypropylene short fibers. Performed at 165 ° C. for about 15 minutes. Each of the obtained composite molded bodies was used as an oil absorbing material, and the oil absorption amount and the oil absorbing speed were measured. The measuring method is as follows.

<Oil Absorption (g / g)> The oil absorption was determined by floating a test piece in a container filled with heavy fuel oil at 19 to 21 ° C., allowing it to stand for 5 minutes, and then placing it on a wire mesh with 15 mm openings for 5 minutes. Leave it alone
The weight of the test piece was measured to determine the increase in weight ratio to the weight of the first test piece. Table 1 shows the results.

<Oil Absorption Rate (sec)> The oil absorption rate was expressed as a time (sec) from when the test piece was floated in a container filled with heavy fuel oil C to when the heavy oil permeated up to the upper portion of the test piece. Table 1 shows the results. The oil-absorbing materials of Examples 1 to 7 had a low density of the composite molded body, and had good strength and oil absorption.

[0034]

[Table 1] ──────────────────────────────────── Example 1 2 3 4 5 6 7 <Manufacturing conditions> Thermal expansion graphite (g) 0.93 1.4 1.4 1.4 1.4 1.4 1.86 PE short fiber (g) 0.93 0.6 1.4 3.23 0 0.7 0.8 PP short fiber (g) 0 0 0 0 1.4 0.7 0 Fiber content (%) 50 30 50 70 50 50 30 Press ratio 1/2 1/3 1/3 1/3 1/3 1/3 1/4 <Compacted body> Weight (g) 1.86 2.0 2.8 4.63 2.8 4.6 2.66 Volume (cc) 97.75 97.75 97.7 97.75 97.75 97.75 97.75 Density (g / cc) 0.019 0.020 0.028 0.047 0.028 0.028 0.027 <Performance> Oil absorption (g / g) 32 28 24 11 26 27 16 Oil absorption speed (sec) 2 to 3 2 to 3 2 to 3 6 〜 7 2 〜 3 2〜3 30 <Strength ○ ○ ○ ◎ ◎ ◎ ◎ ──────────────────────────────── ────

[0035]

×: Collapse during production due to insufficient strength (the same applies hereinafter). Δ: Cracks and the like occur during handling (the same applies hereinafter). ：: Withstands normal handling (the same applies hereinafter). A: Sufficient for normal handling (the same applies hereinafter).

FIGS. 1 and 2 show scanning electron micrographs of the cross sections of the composite molded articles of the present invention obtained in Examples 3 and 5 at a magnification of 95 times (FIG. 1) and 85 times (FIG. 2). From these figures, fusion of the intersection of the short fibers was confirmed.

Examples 8 and 9 In Examples 8 and 9, composite moldings were produced in the same manner as in Example 3, except that the production conditions shown in Table 3 were changed. In Example 8, 13.5 × 10.5c was obtained by heat sealing using the cloth shown in Table 3.
m, and the bag was filled with the composite molded body, and the opening was heat-sealed. In Example 9, the mixture obtained in the first step was surrounded by a nonwoven fabric shown in Table 3, then filled in a mold, pressed, and then heat-treated. Table 3 shows the measurement results.

[0038]

[Table 3] ──────────────────────────────────── Example 8 9 <Manufacturing conditions> Thermal expansion graphite (g) 1.4 1.4 PE short fiber (g) 1.4 1.4 Fiber content (%) 50 50 Press ratio 1/3 1/3 Liquid passing sheet Polyester cloth (about 70g / m^Two) PE non-woven fabric (about 25g / m^Two ) Operating weight (g) 0.99 0.28 <Moldability> Weight (g) 3.79 3.08 Volume (cc) − − Density (g / cc) − − <Performance> Oil absorption (g / g) 20 25 Oil absorption speed (sec) 22 ~ 23 12 ~ 13 Strength ◎ ◎ ────────────────────────────────────

Examples 10 to 12 In Examples 10 to 12, composite moldings were produced in the same manner as in Example 3, except that the production conditions shown in Table 4 were changed. Table 4 shows the measurement results. Oil absorption is enhanced by adding an emulsion breaker.

[0040]

[Table 4] Example 10 11 12 <Manufacturing conditions> Thermal expansion graphite (g) 1.4 1.4 1.4 PE short fiber (g) 1.4 1.4 1.4 Fiber content (%) 50 50 50 Press ratio 1/3 1/3 1/3 emulsion breaker Calcium chloride Calcium carbonate-Use Weight (g) 0.45 0.45 − Addition rate (%) 13.8 13.8 − <Compact> Weight (g) 3.25 3.25 2.8 Volume (cc) 97.75 97.75 97.75 Density (g / cc) 0.033 0.033 0.028 <Performance> Residual oil amount (ppm) ) 163 150 1500 Oil absorption speed (sec) 2-3 3 2-3 2-3 Strength ○ ○ ○ ──────────────────────────── ────────

The residual oil content (ppm) in Table 4 was measured as follows. Thermal expansion super graphite 0.5 g PE short fiber 0.5 g,
Using a mold having an emulsion breaker of 0.16 g and an inner diameter of 3 cm, a cylindrical composite molded article having an outer diameter of about 3 cm and a height of 4.9 cm was produced. The above composite molded body has an inner diameter of 3c.
m, 30 cm height, packed into the bottom of a column for a chemical experiment.

5000 ppm of salad oil and surfactant (“Neo Perex No. 6F powder” manufactured by Kao Corporation) 5
Using 1000 g of an aqueous solution of a dispersion oil in which 00 ppm was dissolved, the solution was passed from the upper part of the column tube at a linear flow rate of 5 cm / min. The residual oil concentration was determined by extracting the liquid flowing out from the lower part of the column with hexane, heating the obtained hexane at 80 ° C. for 0.5 hour and drying, and measuring the weight of the salad oil.

[0043]

The composite molded article of the present invention described above has:
It is lightweight, porous, easy to handle and has excellent absorbency. Therefore, it is useful as an oil absorbing material.

[Brief description of the drawings]

FIG. 1 is a drawing-substitute photograph of a cross section of the composite molded article of the present invention obtained in Example 3, which is a scanning electron micrograph at a magnification of 95 times.

FIG. 2 is a drawing substitute photograph of a cross section of the composite molded article of the present invention obtained in Example 5, which is a scanning electron micrograph at a magnification of 85 times.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication location C01B 31/04 101 C01B 31/04 101A C02F 1/28 C02F 1/28 N 1/40 1/40 E

Claims (6)

[Claims] 1. A thermally expanded graphite composite molded article comprising a thermally entangled matrix in which an intersecting point of short fibers is fused with an entangled matrix. 2. The heat-expandable graphite composite article according to claim 1, which is surrounded by a liquid-passing sheet. 3. The thermally expanded graphite composite molded article according to claim 1, wherein the composite molded article and the liquid-permeable sheet are at least partially fused. 4. The method according to claim 1, wherein a mixture of the heat-expanded graphite and the thermoplastic resin-based short fibers is filled in a mold, pressed, and heated to a temperature at which the short fibers are fused to each other. 4. The method for producing a thermally expanded graphite composite molded article according to any one of 1 to 3 above. 5. A mixture of thermally expanded graphite and thermoplastic short fibers is surrounded by a liquid sheet, filled in a mold, pressed, and heated to a temperature at which the short fibers are fused to each other. A method for producing the thermally expanded graphite composite molded article according to claim 1. 6. An oil absorbing material comprising the thermally expanded graphite composite molded product according to claim 1.