JPH10317297A - Cellulosic ester-containing sheet and is production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a sheetlike molded product, excellent in specific surface area, sheet strength, elongation and bulkiness and suitable for an air filter by blending a cellulosic ester with a fibrillated material and/or a filmy material and binder fibers into a sheet of paper. SOLUTION: This cellulosic ester-containing sheet comprises >=40 wt.% cellulosic ester and >=15 wt.% fibers having binder functions and has >=2 m<2> /g specific surface area and >=4.0 cm<3> /g specific volume. The sheet is obtained by mixing >=40 wt.% cellulose diacetate fibers with a fibrillated material and/or a filmy material having 0.1-30 μm width and 10 μm to 10 mm length and further >=5 wt.% content of the fibrillated material and/or filmy material having >=1,000 μm length and >=4 m<2> /g specific surface area, e.g. acetate fibrils and further adding >=15 wt.% binder fibers such as polyester-based thermally fusible fibers and carrying out wet papermaking. The resultant cellulosic ester-containing sheet further has >=400 g/15 mm tensile strength in at least one direction and >=2%/15 mm tensile elongation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a novel cellulose ester-containing sheet suitable for use in an air filter, particularly a cigarette filter. More specifically, the present invention relates to a cellulose acetate-containing sheet having a high specific surface area, excellent bulkiness, and high sheet strength.

[0002]

2. Description of the Related Art Conventional types of cigarette filters include cellulose acetate, paper filters, rayon filters, and filters in which activated carbon fine particles are wrapped. However, paper and rayon filters have a disadvantage that they adsorb nicotine component and tar component in smoke well, but at the same time, catch too much water, making the taste spicy and impairing the flavor of tobacco.

[0003] In addition, the activated carbon filter also has a nicotine component,
And adsorbs tar components well, but has a drawback in that it has a remarkable ability to adsorb gaseous phase components in the smoke, thereby deteriorating the taste and furthermore, smelling when smoking.

On the other hand, a filter made of cellulose acetate fiber has a good hygroscopicity which does not impair the flavor and taste as compared with pulp paper or rayon filter.
It has a filtering effect on solids and liquids in smoke, and has an appropriate adsorption capacity for nicotine and tar components.

[0005] As described above, the cellulose acetate filter has excellent adsorption characteristics as compared with other tobacco filter materials. Therefore, most of the tobacco filter material is made of a cellulose acetate filter, particularly a cellulose diacetate material.

However, in recent years, the relationship between smoking and health has been taken up as a very serious problem, and there has been a strong demand for increasing the rate of removal of nicotine and tar components from tobacco.

As a result, various studies have been made to fully utilize the goodness of the acetate material and to achieve the object.

As a specific measure, a method of increasing the adsorption area of a filter has been proposed. As examples, studies have been made on (1) a method of reducing the fineness of the acetate fiber to a fine denier, (2) development of a fiber having a modified cross section, and (3) further increasing the filter length.

[0009] Acetate fibers for cigarette filters are generally manufactured by a dry spinning method. In the case of manufacturing by dry spinning, it is necessary to stay for a certain time in order to evaporate the solvent in a heated atmosphere in a spinning tower, and there is a limit in improving the spinning speed. For this reason, in order to reduce the fineness as in the case of (1), there is a method of increasing the spinning draft ratio represented by the ratio of the speed at which the matured liquid is extruded from the nozzle to the winding speed. However, the spinning draft ratio of ordinary acetate fibers for cigarette filters is 1 or less,
Increasing this is not practical because the draft cuts frequently. Further, although a certain degree of denier can be achieved by reducing the nozzle hole diameter and the discharge amount, a reduction in productivity is inevitable. Also, the modified cross-section fiber of (2),
Even when the filter length in (3) is increased, the productivity of the acetate fiber is the same as before. In the case of (3), the cost is unavoidable because the amount of acetate fiber used increases.

In order to solve these problems, a novel cellulose acetate material for a tobacco filter has been proposed. In particular, there has been proposed a method of using a fiber structure having a large specific surface area, which is called a fibril-like fiber, has a large number of branch structures, has a cross-sectional structure of the fiber having irregularities, and has a surface structure in which the side surface of the fiber is very prominent. ing.

For example, Japanese Patent Publication No. 50-38720 proposes a filter material for cigarette by combining other fibers as a cellulose acetyl derivative-based fiber having a high specific surface area.

In a cigarette filter using the fibril-like fiber structure, the aerosol contained in cigarette smoke is adsorbed and captured while repeatedly colliding with the fibril-like fiber structure without short-passing. Tar content can be effectively removed and shows excellent filtration characteristics.

Japanese Patent Publication No. 38720/1983 proposes a method for forming a web in which cellulose diacetate and cellulose diacetate fiber or softwood pulp having a high specific surface area are mixed, and forming the web into a plug.
The sheet obtained by such a method has poor strength and elongation, and it is possible to prepare a plug on a trial basis, but it is not sufficient when considering the industrial scale. Further, a method has been proposed in which a mixture of a fibril-shaped cellulose ester molded product and a cellulose ester short fiber is molded into a sheet and then molded into a rod for a cigarette filter.
(JP-A-53-45468). The purpose of using the fibril-like cellulose ester is to form a filter rod having a high specific surface area and a high filtration property by mixing the fiber having a high specific surface area with the cellulose ester staple fiber, while the sheet strength at the time of lot molding. The purpose is to improve. However, the strength of the formed sheet is 200 to 1000 g / 50 mm, which is not sufficient for forming a filter rod.

[0014]

SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet-like molded article made of a cellulose ester having a specific surface area, a sheet strength, an elongation, and a bulkiness, which is suitable for an air filter, particularly for a cigarette filter.

[0015]

A first gist of the present invention is as follows.
A cellulose ester content of 40% by weight or more, a fiber having a binder function of 15% by weight or more, a specific surface area of 2 m ² / g or more, and a specific volume of 4.0 cm ³ / g or more. Cellulose ester-containing sheet, more preferably, at least one direction has a tensile strength of 400 g / 15 mm or more, and a tensile elongation of 2% / 15 m
m or more.

The cellulose ester has a width of 0.1.
a fibril-like material and / or a film-like material having a length of 10 μm to 30 μm and a length of 10 μm to 10 mm;
The proportion of fibrils and / or films having a length of at least 5 μm is at least 5% by weight and the specific surface area is at least 4 m ² /
g or more, and a sieving test (JIS P-820
7) a fibril-containing cellulose ester having a 150 mesh passing amount of 10% by weight or less, and / or
It is preferable to include a cellulose ester fiber cut fiber. More preferably, the cellulose ester is 2
0% by weight or more of the fibril-containing cellulose ester.

Further, as the cellulose ester, preferably, cellulose acetate, more preferably, cellulose diacetate is used.

Furthermore, as the fiber having a binder function, it is preferable to use at least one selected from wood pulp, cotton pulp, hemp pulp, and heat-sealing fiber.

The second gist of the present invention resides in that a cellulose ester having a binder function of at least 40% by weight and a fiber having a binder function
A method for producing a cellulose ester-containing sheet, characterized in that a mixture comprising 5% by weight or more is subjected to wet papermaking and then dried by a through-dry method.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific examples of the cellulose ester of the present invention include cellulose (mono) acetate, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, benzylcellulose, and a mixture thereof. Cellulose acetate, more preferably cellulose diacetate, is selected.

In the present invention, as the cellulose ester component other than the fibril-containing cellulose ester, cut fibers of cellulose ester fibers are preferable, and by including these fibers, the bulkiness of the sheet can be efficiently improved. The fiber denier, cross-sectional shape, etc. are not particularly limited, but in the sense of increasing bulkiness, a Y-shape,
It is advantageous to have a + cross section. The length of the cut fiber can be appropriately selected according to the fiber diameter.

The term "fibril-containing cellulose ester" used in the present invention refers to a fiber having a structure in which countless fine fibers having a thickness of about 0.1 μm to about 100 μm for forming a three-dimensional network are branched. Means the aggregate, the length of the fiber is several tens μm to 10m
m. Furthermore, the fibril-like material having a width of 0.1 μm to 30 μm and a length of 10 μm to 10 mm, and / or a film-like material, and having a length of 1000 μm or more, has a ratio of 5 μm or more. % By weight or more, a specific surface area of 4 m ² / g or more, and 150 in a sieving test (JIS P-8207).
Those having a mesh passage of 10% by weight or less are preferably used. The cellulose ester of the present invention needs to have both a specific surface area sufficient for adsorbing / filtering nicotine and tar components, and physical properties suitable for processing into a cigarette filter.

The specific surface area of cellulose acetate tow currently used for tobacco filters is at most 0.3 m ^2.
/ G, and also about 1 m ² / g in a cigarette filter using cellulose pulp, and the specific surface area of the cellulose ester sheet of the present invention is 2 m ² / g or more. We can show enough.

In order to ensure that the specific surface area of the cellulose ester sheet of the present invention is 2 m ² / g or more, the specific surface area of the fibril-containing cellulose ester is 4 m ² / g or more.
is necessary. In the wet papermaking method preferred as the sheet forming method of the present invention, if the fiber length is insufficient, the fibers fall off in the sheet forming step and cause a reduction in yield, and are not economical. In the step of continuously feeding the sheet material to the drying step or the step of winding the sheet material around the filter plug, the strength of the sheet material itself is required. In particular, a sheet-like material made of a cellulose ester has lower affinity for fibrils and / or film-like materials due to hydrophobic substituents than cellulose, and tends to have lower strength as a sheet-like material. For the above reasons, the fibril-containing cellulose ester used in the present invention has a width of 0.1 μm to 30 μm and a length of 10 μm.
5 to 10% by weight of a fibril-like material and / or a film-like material having a length of 1000 μm or more, which is composed of a fibril-like material and / or a film-like material having a length of 10 to 10 mm.
And the sieving test (JIS P-820
Those having a mesh passing through 150 mesh of 10% by weight or less in 7) are preferably used.

The cellulose ester-containing sheet of the present invention comprises the above cellulose ester in an amount of at least 40% by weight.
Must be contained, more preferably 60% by weight.
That is all. If the content is less than 40% by weight, the excellent flavor and taste characteristics of the cellulose ester are impaired.

The sheet of the present invention has a specific volume of 4.0 cm ^3.
/ G or more, and the tensile strength in at least one direction is 400 g / 1.
It is preferable that the requirement of 5 mm or more, and more preferably, elongation of 2% / 15 mm or more is satisfied. Since the sheets used for the filter material for cigarettes are bundled and formed into a plug, uniformity in the bundled state is important. When the specific volume of the sheet decreases, the cross-sectional direction of the plugs obtained by bundling tends to be uneven,
Voids are formed, which impairs the original filter function. For this purpose, it is important to increase the bulkiness of the sheet, and as a guide, the specific volume is at least 4.0 cm ³ / g.

The sheet of the present invention needs to have a tensile strength in at least one direction of 400 g / 15 mm or more, more preferably 2% / 15 mm or more. At least one direction means, for example, when forming a sheet by papermaking,
Generally, the strength varies depending on the papermaking direction and the direction perpendicular to the papermaking direction. For example, it means the strength in the papermaking direction, and this value is preferably 400 g / 15 mm or more.
The reason for this is that when forming into a plug, it is common to form a plug with a plug machine while stretching in the papermaking direction, and the sheet strength is at least 400 g / 15 mm or more. Further, preferably, the elongation is 2% / g or more, so that the plug can be more stably formed.

When the bulkiness is improved, there is a problem that the strength of the sheet is reduced. In order to simultaneously satisfy bulkiness and sheet strength, which are requirements of the sheet of the present invention, it is necessary to mix fibers having an appropriate binder function. Examples of the fibers having a binder function include wood pulp, cotton pulp, hemp pulp-like throat pulp, and heat-fused fibers such as polyethylene, polypropylene, and polyester. The mixing ratio is preferably as small as possible in order to maintain the original flavor and taste of tobacco, but in order to achieve the target strength of the sheet of the present invention, it is necessary to contain at least 15% by weight.

The cellulose ester-containing sheet of the present invention is obtained by wet-making a mixture comprising at least 40% by weight of a cellulose ester and at least 15% by weight of a fiber having a binder function, and then drying the mixture by a through-dry method. Can be.

As a method of forming the sheet, either a wet papermaking method or a dry papermaking method can be used. The wet papermaking method is capable of uniformly forming a sheet and has a more hygroscopic property than cellulose. Superior for inferior synthetic fibers. That is, the hygroscopic synthetic fiber is apt to generate static electricity in a dry state, and causes troubles in the process due to static electricity in a dry papermaking system. Furthermore, the sheet of the present invention can be efficiently manufactured by drying without pressing after forming the sheet by a wet papermaking method. As such a drying method, a through dryer, a belt dryer and the like can be used, but it is not particularly limited.

[0031]

Next, the present invention will be described specifically with reference to examples. Example 1 284 g of cellulose diacetate (MGH, manufactured by Daicel Chemical Industries, Ltd.) was added to 703 g of acetone and water 1
It was dissolved in a solution to which 3 g was added to obtain a 28.4% by weight solution of cellulose diacetate. 1.5 kg /
The mixture was extruded under nitrogen pressurization of cm ² , and a fixed amount of water was supplied to the nozzle shown in FIG. 1 using a gear pump, and at the same time, water vapor was supplied. The supply amount of steam was controlled by regulating the supply pressure with a pressure reducing valve. The amount of water vapor was measured by ejecting only water vapor from the nozzle shown in FIG. 1 into the coagulating liquid and calculating the weight increase per unit time. A solution discharge port having a Y-shaped cross-sectional shape shown in FIG. 2, a cylindrical mixing cell having a diameter of 2 mmφ and a length of 1.5 mm, a water vapor passage having a slit shape and an opening of 250 μm were adjusted. Using a nozzle manufactured so that the angle between the center line and the slit center line is 30 degrees, the supply amount of the solution is 48 ml / mi.
n, with the supply pressure of water vapor being 2.5 kg / cm ² , the water was jetted into water at a temperature of 30 ° C. The water vapor consumption at this time was 150 g / min in terms of water, and the linear flow velocity of water vapor in the mixing cell was calculated to be about 750 m / sec. The coagulated body of cellulose acetate suspended in the coagulated liquid was collected, and further washed in boiling water for 1 hour or more. The obtained coagulated product was filtered to obtain a hydrated fibril aggregate. The solid content weight of the hydrate was about 27%. This hydrous fibril was dispersed again in water to prepare a fibril dispersion of about 0.5 wt%. The fibril dispersion was diluted and the freeness was measured. The freeness was measured using a Canadian freeness tester in accordance with JIS P-8121. The value corrected to the standard temperature of 20 ° C. and the standard concentration of 0.30% was 606 ml. In addition, the sieving test was conducted according to JIS P-
When carried out in accordance with 8207, the passing through 150 mesh was 3.9%. Next, this hydrous fibril aggregate was dried with hot air at 80 ° C., and the obtained coagulated body was observed for its fiber cross-sectional shape using a scanning electron microscope. Furthermore, the shape of the fiber in the longitudinal direction was observed using a projection stereo microscope (Nippon Kogaku's profile projector V-12). The obtained solidified body has a thickness of sub-μm to 20 μm,
It was a fibril-like or film-like aggregate having a length of several tens of μm to several mm. The aggregate had a portion having a branched structure, and a tree-like branched structure was observed as a whole. The specific surface area of this aggregate was measured using an automatic specific surface area measuring device (Gemini 2375 manufactured by Micromeritics Co., Ltd.), and was 5.4 m ² / g. 40 parts by weight of the obtained acetate fibrils, 5 denier cellulose diacetate fiber 30 having a Y-shaped cross section cut into 3 mm
Parts by weight, and 30 parts by weight of polyester-based heat-fusible fiber N720 (manufactured by Kuraray Co., Ltd.) were mixed, and PolyEthyl was used as a tackifier.
After adding the eneOxide-based polymer, sheets were formed by a wet papermaking method. The papermaking method was a short net, and the drying method was continuous drying with a through drier. The drying temperature was 150 ° C. and the winding speed was 5 m / min. The obtained sheet has a basis weight of 50 (g / m ² ), a sheet thickness of 0.31 mm, a specific volume of 6.3 cm ³ / g, a specific surface area of 2.2 m ² / g, a tensile strength of 920 g / 15 mm, and a tensile elongation. Was 6.5% / 15 mm.

(Example 2) 40 parts by weight of acetate fibril prepared in the same manner as in Example 1, 20 parts by weight of cellulose diacetate fiber cut into a Y-shaped cross section of 5 denier and 3 mm in length, polyester-based heat fusion fiber N720 ( 40 parts by weight of Kuraray) were mixed in the same manner, and
After the addition of yEthylene Oxide-based polymer, sheets were formed by a wet papermaking method. Similarly, the paper making method was a short net, the drying method was a through drier, the drying temperature was 150 ° C., and the winding speed was 5 m / min. The obtained sheet has a basis weight of 58 (g / m ² ), a sheet thickness of 0.32 mm, a specific volume of 5.5 cm ³ / g, and a specific surface area of 2.
3 m ² / g, tensile strength 750 g / 15 mm, tensile elongation 4.6% / 15 mm.

Example 3 36.3 parts by weight of acetate fibril prepared in the same manner as in Example 1,
44.5 parts by weight of cellulose diacetate fiber cut to a denier length of 3 mm and 18.2 parts by weight of Manila hemp pulp were mixed, and similarly, Poly Ethylene was added to the adhesive.
After adding the e Oxide-based polymer, the sheet was formed by a wet papermaking method. As in Example 1, the papermaking method was short net, the drying method was a through drier, and the drying temperature was 150.
C. and a winding speed of 5 m / min. The basis weight of the obtained sheet was 50 g / m ² , the sheet thickness was 0.22 mm,
Specific volume 4.4 cm ³ / g, specific surface area 2.3 m ² / g, tensile strength 440 g / 15 mm, tensile elongation 2.5% / 15 m
m.

Example 4 50 parts by weight of acetate fibril prepared in the same manner as in Example 1 and 50 parts by weight of a polyester heat-fusible fiber N720 (manufactured by Kuraray) were mixed.
Similarly, add PolyEthylene Oxi to the adhesive.
After adding the de-based polymer, sheets were formed by a wet papermaking method. Similarly, the papermaking method is a short net, the drying method is a through drier, the drying temperature is 150 ° C., and the winding speed is 5 mm.
m / min. The basis weight of the obtained sheet is 54 (g).
/ M ² ), sheet thickness 0.22 mm, specific volume 4.1 cm ³
/ G, specific surface area 2.5 m ² / g, tensile strength 800 g / 1
It was 5 mm, and the tensile elongation was 5.2% / 15 mm.

(Example 5) 25 parts by weight of acetate fibril prepared in the same manner as in Example 1, 35 parts by weight of cellulose diacetate fiber cut into a 3 denier length of 3 mm in a Y-shape, and polyester heat fusion fiber N720 ( 40 parts by weight of Kuraray) were mixed in the same manner, and
After the addition of yEthylene Oxide-based polymer, sheets were formed by a wet papermaking method. Similarly, the paper making method was a short net, the drying method was a through drier, the drying temperature was 150 ° C., and the winding speed was 5 m / min. The basis weight of the obtained sheet is 55 (g / m ² ), the sheet thickness is 0.28 mm, the specific volume is 5.1 cm ³ / g, and the specific surface area is 2.
0 m ² / g, tensile strength was 710 g / 15 mm, and tensile elongation was 5.0% / 15 mm.

Example 6 40 parts by weight of acetate fibril prepared in the same manner as in Example 1, 30 parts by weight of cellulose diacetate fiber cut into a 3 denier length of 3 mm in a Y-shape, and 30 parts by weight of wood pulp were mixed. Similarly, a Poly Ethylene Oxide-based polymer was added to the adhesive, and then a sheet was formed by a wet papermaking method. Similarly, the papermaking method is short net, the drying method is a through dryer, the drying temperature is 150 ° C., and the winding speed is 5 m / m.
went in. The basis weight of the obtained sheet is 51 (g / g).
m ² ), sheet thickness 0.26 mm, specific volume 5.1 cm ³ /
g, specific surface area 2.1 m ² / g, tensile strength 420 g / 15
mm and tensile elongation were 2.6% / 15 mm.

[0037]

According to the present invention, a cellulose acetate sheet excellent in high specific surface area, sheet strength and bulkiness and suitable for an air filter, particularly a tobacco filter material, is obtained.
This cellulose acetate sheet is excellent in plug workability due to its physical properties and bulkiness, and the cigarette filter using the sheet of the present invention as a material has excellent performance in filtering properties of nicotine and tar, and has acetate fiber. Being able to maintain the flavor is of great industrial significance.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a nozzle used in the present invention.

[Explanation of symbols]

 1: Flow path of cellulose acetate solution 2: Discharge port of cellulose acetate solution 3: Inlet of coagulant fluid 4: Slit of coagulant fluid 5: Mixing cell section 6: Exit of mixing cell section: Discharge line of cellulose acetate solution : Injection line of coagulant fluid: Angle formed with

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] July 4, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of the drawings]

FIG. 1 is a longitudinal section showing an example of a nozzle used in the present invention.
FIG .

FIG. 2 shows a cellulose ester of a nozzle used in the present invention .
FIG. 3 is a cross-sectional view of a discharge port of the liquid solution.

[Description of Reference Numerals] 1: flow path 2 of the cellulose ester solution: outlet of the cellulose ester solution 3: inlet coagulant fluid 4: slit coagulant fluid 5: Mixed cell part 6: the outlet of the mixing cell part: Cellulose Ester solution discharge line: Coagulant fluid injection line: Angle formed with

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Megumi Hirota 3 Kaigan-dori, Toyama City, Toyama Prefecture Mitsubishi Rayon Co., Ltd. Toyama Works

Claims (9)

[Claims] 1. A cellulose ester comprising at least 40% by weight,
Contains 15% by weight or more of a fiber having a binder function,
The specific surface area is 2 m ² / g or more, and the specific volume is 4.0 cm ³ /
g or more. 2. A tensile strength in at least one direction of 40.
The cellulose ester-containing sheet according to claim 1, wherein the sheet has a tensile elongation of 2 g / 15 mm or more. 3. A cellulose ester having a width of 0.1 μm.
Composed of a fibril-like material and / or a film-like material having a length of 10 μm to 10 μm and a length of 10 μm to 10 mm.
m or more, the proportion of the fibril-like material and / or the film-like material is 5% by weight or more, and the specific surface area is 4 m
² / g or more, and sieving test (JIS P-8
The cellulose ester-containing sheet according to claim 1 or 2, wherein the cellulose ester-containing sheet contains a fibril-containing cellulose ester having a 150 mesh passing amount of 10% by weight or less in 207). 4. A cellulose ester containing at least 20% by weight of a fibril-containing cellulose ester.
The cellulose ester-containing sheet according to the above. 5. The cellulose ester-containing sheet according to claim 3, wherein the cellulose ester contains cut fibers of cellulose ester fibers. 6. The cellulose ester-containing sheet according to claim 1, wherein the cellulose ester is cellulose acetate. 7. The cellulose ester-containing sheet according to claim 6, wherein the cellulose acetate is cellulose diacetate. 8. The cellulose ester-containing sheet according to claim 1, wherein the fibers having a binder function include at least one selected from wood pulp, cotton pulp, hemp pulp, and heat-sealing fibers. . 9. A method for producing a cellulose ester-containing sheet, comprising: wet-making a mixture of 40% by weight or more of cellulose ester and 15% by weight or more of a fiber having a binder function, followed by drying by a through-dry method. Method