JP2014073938A - Method and device for carbonizing regenerated cellulose film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple method with mass production adaptability for carbonizing a regenerated cellulose film in which handling property is improved at the time of manufacturing and in which cracks and wrinkles are hard to be generated, and a device suitable for mass production using the method.SOLUTION: A regenerated cellulose film to be carbonized is fired and carbonized at high temperature under an oxygen shielding atmosphere or a low oxygen atmosphere in the state in which the regenerated cellulose film is sandwiched by sheets composed of a cellulosic fiber consisting mainly of pulp and pressured after sandwiching the sandwiched one with heat resistant members. Handling property is improved by protecting the regenerated cellulose film with the sheets composed of the cellulosic fiber consisting mainly of pulp during carbonization process.

Description

  The present invention relates to a method for flatly carbonizing a regenerated cellulose membrane and an apparatus suitable for mass production by the method.

Viscose membranes (cellophane), which are representative of regenerated cellulose membranes, are produced in large quantities and are widely used as inexpensive packaging materials and semipermeable membranes. However, cellophane has low membrane strength and is highly hydrophilic and easily absorbs moisture. Therefore, when carbonized in the same way as other polymer film materials, non-uniform shrinkage occurs upon heating, resulting in cracks and wrinkles easily, strength that can withstand practical use, and uniform and free of cracks and wrinkles It was difficult to obtain a film. In order to heat carbonize a film made of non-heat-meltable regenerated cellulose used in the method of the present invention, it is necessary to heat at a temperature of 300 ° C. or higher in a non-oxidizing atmosphere. At that time, if it is left in a high-temperature heating furnace, usually in contact with a heating roll, or heated on a heat-resistant glass or a metal net or flat plate, it is accompanied by carbonization. A non-uniform force is applied during the shrinkage process, and cracks, cracks, undulations and warpage are likely to occur, and the entire surface is smooth and uniform, and a sheet or film-like carbide with a suitable area for practical use is obtained. Was difficult. In particular, when a thin film having a thickness of about 100 μm or less is carbonized, wavy or irregular fine wrinkles are likely to occur, and it is further possible to produce a uniform carbon film without wrinkles with a large area and low cost that can be put to practical use. It was difficult.

One of the inventors of the present invention is a method of carbonizing a wood-based material, for example, wood, in which the wood-based material is disposed between two heat-resistant flat plate members, and the interval between the flat plate members is set to the thickness of the wood-based material. A method of baking and carbonizing at a high temperature in an oxygen-blocking atmosphere or a low-oxygen atmosphere while keeping a little larger than that was filed (Japanese Patent Application No. 2011-176539). This method is very effective for carbonizing relatively thin woody materials such as warp wood and paper. However, when this method was applied to carbonization of a commercially available cellophane (thickness of about 20 μm), it was found that fine lines were generated on the entire surface. When cellophane is fired and carbonized at a high temperature of around 750 ° C., it becomes a very thin film with a thickness of 9 μm and exhibits high electrical conductivity. It becomes a very promising material as a thin conductive film obtained from existing cellulose.

  Therefore, as a result of repeating the experiment, the present inventors have found that a flat cellophane film is uniformly tensioned along the surface, the material is curved, or these states are combined. It was discovered that fine wrinkles do not occur when carbonized in a state, and a method was filed (Japanese Patent Application No. 2012-085715). For example, if four sides or four corners of a cellophane film of about 10 centimeters square are held by a heat-resistant member and a force is applied to the holding member from the center of the cellophane film outward, the cellophane film is moved along the surface. Tension is applied and the cellophane film becomes flat. It was confirmed that if carbonized in this state, a flat carbonized film without fine lines was obtained.

  Although the above method is an excellent method, the present inventors have found a method that facilitates the handling of the carbonized regenerated cellulose membrane during the carbonization step and can easily carbonize the regenerated cellulose membrane, and have reached the present invention.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a regenerated cellulose membrane that is homogeneous and wrinkle-free, can be carbonized flatly, is easy to handle during the carbonization process, is easy to handle, and a carbonized apparatus for regenerated cellulose membrane suitable for mass production. is there.

In the method of the present invention, a regenerated cellulose membrane to be carbonized is sandwiched between sheets composed of natural cellulose fibers mainly composed of pulp, and the sandwiched body is further sandwiched by a heat resistant member. Firing is performed at a high temperature in an oxygen-blocking atmosphere or a low-oxygen atmosphere in a pressurized state.

The apparatus of the present invention includes at least a means for sandwiching a regenerated cellulose membrane with natural cellulose fibers mainly composed of pulp, and a plurality of sets of heating and pressurizing means for passing the regenerated cellulose membrane sandwiched with the natural cellulose fibers. The heating and pressurizing means comprises a heating roll and a heat-resistant endless belt, and a mechanism in which the heat-resistant endless belt is pressed against a part of the heating roll and a peripheral speed of the heating roll are the same. The temperature of the plurality of sets of heating rolls is increased in order, the peripheral speed is set to be lower in order, and at least the heating portion is disposed in an oxygen-blocking atmosphere or a low-oxygen atmosphere.

According to the method and apparatus of the present invention, a carbon film having an arbitrary area can be manufactured and supplied in a large amount at a low cost according to the application. The method of the present invention is a cellophane film, a regenerated cotton film, etc. made of so-called regenerated cellulose, in which various plant fibers including wood, herbaceous, or cotton are modified and solubilized, and cellulose is regenerated in the film forming process. Powerful for carbonization of thin films with a film thickness of about 100 μm or less. The method of the present invention is also applicable to sheet-like or roll-like materials such as general paper, newsprint, waste paper, etc. that maintain a fibril structure, or roll-like materials, or wood that has been cut into thin sheets like warps. it can. In the sheet-like or film-like carbide obtained by the method of the present invention, there are no cracks or wrinkles, and almost no undulation or warpage occurs. Therefore, the carbon film obtained by the method of the present invention can be used for many applications. Furthermore, carbonization can be continuously performed by sandwiching a short warp between long sheets.

FIG. 1 is an explanatory view showing the method of the present invention. FIG. 2 is an explanatory view showing an embodiment of the apparatus of the present invention.

The raw material used in the present invention is a solution obtained by modifying plant cellulose, a regenerated film or sheet obtained by spreading the film, and a film or sheet obtained by modifying these properties according to the purpose of use. There is. Moreover, the film and sheet-like material which impregnate | supported the regenerated cellulose solution on the paper and the nonwoven fabric are mention | raise | lifted. Examples of the raw material include a film having a semipermeable membrane having a self-supporting property. Among them, cellophane formed from regenerated cellulose is a typical example.

  FIG. 1 is an explanatory view showing an embodiment for explaining the method of the present invention. A regenerated cellulose membrane 10 is sandwiched between sheets 11 and 12 composed of natural cellulose fibers mainly composed of two pulps. Furthermore, it is clamped by two heat resistant members 13 and 14 from both sides. Examples of the sheets 11 and 12 include paper made of natural cellulosic fibers mainly composed of normal pulp such as newsprint, ordinary copy paper, medium quality paper, and Japanese paper, and non-woven fabric. The thickness of the sheets 11 and 12 may be the same or different. Examples of the heat resistant members 13 and 14 include heat resistant glass, ceramic, and metal. The thickness of members 13 and 14 may be the same or different.

Although not depicted in FIG. 1, the member 14 is placed on a heat-resistant base, a heat-resistant weight is placed on the member 13, and the regenerated cellulose film 10 is pressurized. . Examples of the heat-resistant base include ceramic plates, iron plates, stainless steel plates, and the like. Examples of the heat-resistant weight include a metal plate and a ceramic plate. The load applied to the regenerated cellulose membrane 10 is desirably at least about 30 kg / m ² . If the load is smaller than this, fine lines are often generated in the regenerated cellulose membrane after carbonization. If the load is too large, cracks and breaks may occur in the regenerated cellulose membrane after carbonization, so an excessive load must be avoided. Since the upper limit of the load varies depending on the thickness and type of the regenerated cellulose membrane to be used and the thickness and type of the sheet composed of natural cellulose fibers mainly composed of pulp, it is not unconditionally determined. The regenerated cellulose membrane is carbonized by firing at a high temperature in an oxygen-blocking atmosphere or a low-oxygen atmosphere in a state where a load is applied as described above in addition to the configuration of FIG.

  FIG. 2 is an explanatory view showing an embodiment suitable for mass production of the apparatus of the present invention. In FIG. 2, a sheet 16 made of natural cellulosic fibers mainly composed of pulp supplied from a supply roll 15, a regenerated cellulose film 18 supplied from a supply roll 17, and pulp supplied from a supply roll 19 as main components. The sheet 20 made of natural cellulosic fibers is combined with a roller 32 for sandwiching the guide roller / regenerated cellulose film 18 with a sheet made of natural cellulosic fibers into a single sheet 21. It advances along the guide roller 32 and then enters between the endless belt 24 moving at the same peripheral speed as the first heating roller 22 and passes along the circumference of the heating roller 22. The sheet-like body 21 that has come out between the heating roller 22 and the endless belt 24 then enters between the second heating roller 25 and the endless belt 27 and travels around the heating roller 25. Similarly, the sheet-like body 21 further enters between the third heating roller 28 and the endless belt 30, passes along the third heating roller 28, proceeds in the direction of the arrow 31, and is illustrated. Not wound on a winding roll. The carbonized regenerated cellulose film 18 may be wound in a state of being sandwiched between two sheets of carbonized natural cellulosic fibers, but at least one of the carbonized natural cellulosic fiber sheets is wound before being wound. The separated and exposed carbonized regenerated cellulose membrane may be impregnated or coated with a softening agent.

Of the three heating rollers 22, 25, 28, the heating roller 22 has a relatively low carbonization temperature (about 250 to about 350 ° C), and the heating roller 25 has a medium carbonization temperature (about 450 to about 550 ° C). The heating roller 28 is set to a maximum carbonization temperature (about 700 to about 1200 ° C.). The maximum carbonization temperature can be appropriately selected according to the application. It is desirable to set the peripheral speed of the three heating rollers to be smaller in the order of the heating rollers 22, 25, and 28. The reason is that the regenerated cellulose film shrinks as the heating temperature increases, and the regenerated cellulose film in the carbonization process may be broken unless the peripheral speed is controlled accordingly. The temperature and peripheral speed of each heating roller are optimally set according to the type of carbonized material and carbonization conditions. Although only three heating rollers are shown in FIG. 2, it can be changed as necessary. Although not shown in the drawing, the entire carbonization apparatus or at least the heating part is put in a container or a room as in the case of FIG. In order to create a low-oxygen or oxygen-free atmosphere, the device can be in a nearly closed state, or an inert gas can be fed into the device so that no oxygen is present in the device.

  Since the regenerated cellulose membranes have good mutual adhesion, a carbon film material with high film thickness and strength can be easily obtained by carbonizing the two or more regenerated cellulose membranes so that no air or the like enters between them. Can be obtained.

In the carbonization method of the regenerated cellulose membrane according to the present invention, since the regenerated cellulose membrane to be carbonized is always sandwiched between sheets made of natural cellulose fibers mainly composed of pulp during the carbonization step, the regenerated cellulose membrane in the carbonization step is It is protected by these sheets. When carbonized without these sheets, the regenerated cellulose membrane carbonized during the carbonization process frequently breaks. Surprisingly, the presence of these sheets prevents breakage. The reason is considered as follows. Sheets made of regenerated cellulose membrane and natural cellulosic fibers have the same degree of thermal shrinkage. When the regenerated cellulose film is carbonized alone without these sheets, the slipping property between the heat-resistant member (heat-resistant glass, ceramic, metal, etc.) sandwiching the regenerated cellulose film and the regenerated cellulose film is poor, both When the regenerated cellulose membrane undergoes thermal shrinkage, it cannot be uniformly shrunk and breaks at that portion. On the other hand, when a sheet made of natural cellulosic fibers is interposed between the regenerated cellulose membrane and the heat-resistant member, the slip between the sheet and the heat-resistant member is good, and this sheet is heat-resistant during the carbonization process. It is because it does not adhere to the member. Actually, when the regenerated cellulose membrane is directly sandwiched between the glass plates and carbonized, it is recognized that the regenerated cellulose membrane adheres to the heat-resistant glass plates. However, a sheet made of natural cellulose fibers such as paper is directly sandwiched between the glass plates. Thus, even if carbonized, it is not recognized that it adheres to the heat-resistant glass plate, so the above assumption is considered to be appropriate.

  It is described in the invention filed by the present inventors that the porous carbon thin film by the method of the present invention can remarkably improve flexibility and handling properties by applying a flexibility imparting agent to the surface after carbonization. Yes. As the flexibility-imparting agent, various solvents, natural products, or synthesized various oils that are liquid at least at room temperature can be used. For example, various organic solvents such as hydrocarbons, alcohols, esters, ethers, nitrogen, Examples thereof include derivatives containing heteroelements such as sulfur and silicon, organic and inorganic oils, and mixed solvents thereof. These flexibility-imparting agents can be appropriately selected from organic, inorganic solvents or mixed solvents having characteristics according to the purpose of use. Furthermore, an ionic liquid is a very effective flexibility imparting agent.

  Cut from 10 cm x 10 cm size of normal cellophane film with a thickness of 21μ and a size of about 45 cm x 50 cm, which is commercially available as a recycled cellulose film at a stationery store. 0.09 mm). The cellophane film was placed almost in the center of the copy paper. The plate in this state was placed on a ceramic plate (about 220 g) having a size of 15 cm × 15 cm and a thickness of 4 mm, and a ceramic plate of the same size and thickness was stacked thereon. An iron plate having a weight of 1.2 kg and a size of 12 cm × 12 cm was placed on the glass plate and a load was applied. In this state, it was put in a ceramic container that had been in an oxygen-blocked atmosphere, put in an electric furnace, raised from room temperature to 750 ° C. at a rate of 230 ° C. per hour, held at 750 ° C. for 30 minutes, then stopped heating and naturally Allowed to return to room temperature. When the carbonized cellophane film was taken out from the ceramic container and confirmed to be carbonized, a uniform carbonized film was obtained which was almost completely flat and free of fine lines, and the film thickness was about 9 μm. The copy paper sandwiched with cellophane film was also carbonized flat.

Visking tube used for dialysis (VISKING SEAMLESS CELLULOSE
The TUBING tube was crushed into a film-like long roll, and three strips were prepared by cutting the crushed state into a film with a thickness of 51 μm and a width of 33.5 mm. Instead of the cellophane film of Example 1, three of these strips were arranged so as not to overlap the range of about 10 cm × 10.8 cm. Other than that, when carbonized in the same manner as in Example 1, a completely flat cellophane carbonized film was obtained.

  A flat cellophane carbonized film free of fine lines was obtained in exactly the same manner as in Example 1 except that cellophane was sandwiched between two sheets of ordinary copy paper (a total of four copy papers).

  Flat carbonized cellophane free of fine lines was obtained in exactly the same manner as in Example 1 except that newspaper paper was used instead of ordinary copy paper.

  The porous carbon thin film using the regenerated cellulose according to the present invention has high water impermeability, heat resistance and corrosion resistance, and can be produced in large quantities at a low cost. In addition, carbon thin films whose flexibility has been improved by affinity solvents are porous, have affinity for various solvents, and can be easily combined with other membrane materials, so they can be used for ion batteries, fuel cells, and capacitors. It can be used as a functional carbon thin film material such as a separator. In addition, because it can be made conductive on the entire surface, locally or in a pattern, and has excellent processability such as lamination, it is also a functional carbon thin film material in the fields of information electronics and medical equipment such as sensors for measuring equipment. Available. Furthermore, it can be used as a surface protective material for equipment, tools, and containers used in general households, and as a functional film material for packaging materials and building materials for indoor and outdoor use.

DESCRIPTION OF SYMBOLS 10, 18 Regenerated cellulose membrane 11, 12, 16, 20 Sheet | seat 13 and 14 which consists of cellulosic fiber 15, 14 Heat-resistant member 15, 19 Sheet supply roll 17 Regenerated cellulose membrane supply roll 21 Regenerated cellulose membranes 22 and 25 pinched | interposed into the sheet | seat 28 Heating rolls 24, 27, 30 Pressure endless belt 32 Guide and clamping rollers

Claims (2)

  A state in which the regenerated cellulose membrane to be carbonized is sandwiched between sheets composed of natural cellulosic fibers mainly composed of pulp, the sandwiched body is sandwiched between heat-resistant members, and the regenerated cellulose membrane is pressurized. A method for carbonizing a regenerated cellulose film, comprising firing at a high temperature in an oxygen-blocking atmosphere or a low-oxygen atmosphere.   Means for sandwiching at least the regenerated cellulose membrane with natural cellulose fibers mainly composed of pulp, and means for passing the regenerated cellulose membrane sandwiched with the natural cellulose fibers through a plurality of heating and pressurizing means; The heating and pressurizing means includes a heating roll and a heat-resistant endless belt, and a mechanism in which the heat-resistant endless belt is pressed against a part of the heating roll and a mechanism driven at the same speed as the peripheral speed of the heating roll. The regenerated cellulose membrane is characterized in that the temperature of the plurality of sets of heating rolls is high in order, the peripheral speed is set to be low in order, and at least the heating portion is arranged in an oxygen-blocking atmosphere or a low-oxygen atmosphere. Carbonization equipment.