JPS5941714B2 - Porous body for cigarette filter and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a porous body for a cigarette filter having through holes and a method for manufacturing the same.

In order to reduce the physiological and sanitary effects caused by smoking, cigarettes, especially cigarettes, are mainly used to produce cigarettes with a built-in filter (hereinafter referred to as filter cigarettes).

) is widely used. A filter cigarette is defined as having a filter at one end containing an adsorbent capable of adsorbing tar and irritants, so that tobacco smoke passes through the filter before being absorbed into the smoker's body. refers to tobacco products that have been

The filter must not substantially interfere with the enjoyment of smoking in terms of flavor and must remove tar and irritants from the smoke while not obstructing the passage of air through the filter.

Traditionally, acetate tow has been overwhelmingly used as a cigarette filter, but other types such as viscose rayon, polypropylene,
It is also known to use fibers such as polyamide and polyacrylic.

However, with the exception of polyamide fibers, these filters have the drawback of not being able to sufficiently remove harmful substances such as polyphenols.

Furthermore, when polyamide fiber alone was used as a filter, it was not possible to sufficiently adsorb harmful substances other than polyphenols.

The present inventors completed the present invention as a result of intensive research to develop a filter with excellent adsorption and filtration ability for these harmful substances.

The gist of the present invention is that polyamide and acetic acid degree of 53
As a result of X-ray diffraction measurements, ~58% of cellulose acetate was dispersed in a finely mixed state of less than 1 μm without exhibiting any crystallinity or orientation, and was substantially integrated. A porous body with a porosity of 30 to 80%,
A porous body for a cigarette filter, characterized in that the porous body has through-holes with an average pore diameter of 0.1 μm to 1 μm, the orientation angle of the long axis of which is substantially perpendicular to at least one coordinate axis, and a polyamide and cellulose acetate with an acetylation degree of 53 to 58% as a mixture in a solution of an aliphatic primary alcohol having 4 or less carbon atoms containing an alcohol-soluble deliquescent inorganic compound. production of a porous material for a cigarette filter, which is characterized in that the inorganic compound is dissolved in water, then wet-spun into an aqueous coagulation bath at a draft of less than 1.0, and at the same time the inorganic compound is dissolved and removed, or the inorganic compound is removed by washing after wet-spinning. It is the law.

The most important feature of the porous material for cigarette filters of the present invention is that the polyamide and cellulose acetate exhibit no crystallinity and are hardly oriented, with fine particles of 1μ or less in size, as measured by X-ray diffraction. A porous body that is dispersed in a mixed state and substantially integrated, the porosity of which is 30 to 80, and the orientation angle of the long axis of the porous body is substantially aligned with at least one coordinate axis. Average pore diameter perpendicular to 0.1 μ to 1
It has a through hole.

Cigarette filters using conventional polymer materials are in the state of fibers, and the molecular chains that make up the fibers are oriented in the fiber axis direction.
While the crystallinity is approximately 30 coefficients or higher, the molecular chains of the porous material of the present invention are not oriented, and therefore the crystallinity is 10 coefficients or lower, which is so low that it does not show any crystallinity in X-ray diffraction. Therefore, it has particularly excellent adsorption performance for polyphenols.

The larger the porosity of the porous body, the better; however, if it becomes too large, the mechanical properties of the porous body deteriorate, and an increase in the porosity causes a quantitative decrease in adsorbed substances.

Therefore, the porosity is usually 80 or less. Especially 50-70
Rice cake is preferred.

In addition, for porous bodies with the same porosity, the smaller the average diameter r, the better the adsorption performance, but the resistance when gas passes through the porous body is approximately equal to the square of the average pore diameter r. Since it is inversely proportional, the minimum average pore diameter of a porous filter material is
The lower limit is 0.1μ, and the value of r of the porous body is 20 to 2
00μ is preferable, and is characterized by forming a through hole and communicating with the outside world.

A second feature of the invention is that the orientation angle of the long axis of the through hole is substantially perpendicular to at least one coordinate axis.

More preferably, the orientation angle is substantially perpendicular to two orthogonal coordinate axes, that is, the direction of the through hole is oriented in a constant direction.

By oriented the through holes in this way, even if the average pore diameter and porosity are small, the resistance when gas passes through the porous body can be reduced, making it an extremely excellent cigarette filter. It is something.

That is, there are advantages such as the fact that it is easy to determine the direction of air flow when used as a cigarette filter, and the conventional work of arranging and bundling tows can be omitted.

The long axis here means the direction in which the hole penetrates, and usually corresponds to the direction of the long axis when the hole is approximated as an ellipsoid.

An orientation angle of a major axis substantially perpendicular to at least one coordinate axis means that the major axis is oriented in a plane.

The third feature of the present invention is that the polymeric materials constituting the porous body are polyamide and cellulose acetate with an acetylation degree of 53 to 58, but both components are dispersed in a finely mixed state of 1μ or less, and the porous body is The point is that the body is essentially one.

Here, to explain the mixed state of 1μ or less, when a sample is generally composed of two types of polymeric materials and the two components do not mix in molecular form,
The dispersion state of each component changes depending on the component composition.

Now considering a system composed of components A t and B, if component A accounts for 70% or more of the composition, component A forms a support layer, and the remaining component B becomes dispersed particles.

A state in which the diameter of the dispersed particles is 1 μm or less is defined as a mixed state of 1 μm or less.

When the composition of component A is in the range of 30 to 70%, the distinction between the support layer and the dispersed particles becomes unclear, but components with a composition of 50% or less are considered to be dispersed particles, and aggregates of this component are treated as dispersed particles. A state in which the size is 1 μ or less is defined as a mixed state of 1 μ or less.

By finely dispersing one component in this manner, the gas molecule adsorption performance is significantly improved.

For example, after dispersing a fine powder of nylon 6 in a 10% acetone solution of cellulose acetate, the adsorption amount of polyphenols on the film determined by the solvent evaporation method (the amount of adsorption at 20°C for 220 minutes) is equal to the number of particles of the fine nylon 6 powder. The amount of adsorption increases as the weight increases, and when a powder with a diameter of 10 μm, a powder with a diameter of 1 μm, and a powder with a diameter of 1 μm are compared at the same weight, the adsorption amount increases by 1:1.5.

Next, regarding the ratio of polyamide in the porous body, the greater the amount of polyamide, the better the adsorption ability for polyphenols, but the more the adsorption ability for nicotine and tar decreases.

Therefore, the mixing ratio of polyamide and cellulose acetate is
It is determined by the most preferable composition ratio between the adsorption capacity for irritants such as nicotine and tar and the adsorption capacity for polyphenols.

From the viewpoint of stability, it is most effective when the ratio of the polyamide amount is between 5 and 60 parts.

Next, the method for manufacturing the porous body of the present invention will be described in detail.

Polyamides used in the present invention include nylon 6, nylon 6-10, nylon 6-12, nylon 6
-6 etc. are suitable.

Particularly suitable are nylon 6 and nylon 6-10.

First, as a solvent, a solution of an aliphatic primary alcohol having 4 or less carbon atoms containing an alcohol-soluble deliquescent inorganic compound is prepared.

At this time, it is not necessary to use a saturated solution, but a concentration as high as possible improves the solubility of the polyamide and cellulose acetate.

A mixture of polyamide and cellulose acetate is dissolved in the solution in an amount of 8% by weight or more and 20% by weight or less, and the mixture is used as a spinning stock solution.

The porous body of the present invention can be obtained by wet spinning the spinning stock solution into an aqueous coagulation bath at a draft of 1.0 or less.

Here, as the alcohol-soluble deliquescent inorganic compound, at least one inorganic compound selected from the group of calcium chloride, lithium chloride, aluminum chloride, magnesium chloride, calcium nitrate, lithium nitrate, and aluminum nitrate is particularly preferred.

Examples of aliphatic primary alcohols having 4 or less carbon atoms include methyl alcohol, ethyl alcohol, flobyl alcohol,
One type of alcohol selected from the group of n-butyl alcohol and t-butyl alcohol is used.

As the aqueous coagulation bath, a dilute aqueous hydrochloric acid solution or a dilute aqueous phosphoric acid solution is preferable. By using dilute hydrochloric acid or a dilute aqueous phosphoric acid solution in the coagulation bath, the deionization rate of metal ions during the formation of a porous body is improved and the formation of through holes. It has extremely excellent effects.

In addition, by wet spinning with a draft of 1.0 or less,
A porous fiber having through-holes oriented in the longitudinal direction of the fiber and having unorientated molecular chains can be obtained.

When wet spinning is carried out under conditions where the draft is higher than 1.0, orientation of the molecular chains occurs and the degree of crystallinity increases.
This results in a decrease in the adsorption capacity of a cigarette filter.

The coagulation bath temperature is related to the average pore diameter of the porous body, especially 5
A temperature in the range of ~35°C is preferable because it forms a pore size suitable for a cigarette filter.

When the coagulation bath temperature is 35°C or higher, the pore diameter increases,
When the temperature is 5° C. or lower, a porous body with a small pore diameter, which is not suitable for use as a cigarette filter in terms of airflow passage resistance and mechanical properties, may be formed.

Various physical property measurement methods (1) Adsorption rate measurement method Using an automatic smoking device, the test conditions were as follows: A porous filter was attached to one end of a commercially available double-cut piece, and the temperature was 20TL for 1 second.
Inhale at a flow rate of 2 times for 2 seconds at a time for 30 seconds until 30 degrees of watermelon remains, and measure the amount A of nicotine adsorbed on the filter and the amount B of nicotine in the smoke that passed through the filter. It is calculated using the following formula.

Nicotine adsorption rate = X100 (%) Tar adsorption rate and polyphenol adsorption rate are calculated in the same manner.

(2) Porosity (Pr) The apparent density ρa was measured and determined from the following equation.

Pr=(1-ρa/ρf)×100(%) where,
ρf is the density of the sample, for example 1.3 for cellulose acetate.
0 (g/1rLl), 1.16 (g/1rLl) for nylon 6
/ml).

In the case of a mixture of cellulose acetate and nylon 6, the following holds true, where the respective weight fractions are Wl and W2.

(3) A scanning electron microscope and an optical microscope were used to measure the average pore diameter and observe through holes.

(4) Determination of crystallinity/non-quality and determination of degree of orientation.

Qualitative determination is made using wide-angle X-ray diffraction photographs.

X-ray wide-angle diffraction photographs were recorded on a flat film using an X-ray generator M manufactured by Shimadzu, type X-2, at a tube voltage of 30 KV, a tube current of 18 mA, and a camera length of 30 degrees.

Crystallinity/non-quality is determined by scanning this film with a Rigaku microdensitometer and observing the diffraction pattern. A pattern that does not show any diffraction peaks based on crystalline regions is determined to be non-quality.

The presence or absence of orientation of polymer chains is determined by observing the azimuthal direction of the film and observing links or circular arcs.

Example 1 50 g of calcium chloride dihydrate was dissolved in 100 g of methyl alcohol.
5 g of nylon 6 (viscosity average molecular weight 200
00) chips and 10 g of cellulose acetate (degree of acetylation 54.
1% and average polymerization degree of 19.2) and stirred at room temperature for 96 hours to prepare a nylon 6/cellulose acetate solution.

The solution viscosity at 25°C was 780 poise.

After degassing under reduced pressure, use Q, l tinφ1 as a spinneret.
00 hole into a coagulation bath prepared with 25°c t 3% diluted hydrochloric acid aqueous solution at a linear velocity of 6 m/m1n1 trough)
Wet spinning was carried out at a speed of 0.9.

The obtained porous fiber had a single fiber diameter of 150μ and a porosity of 65.
H. It had through-holes with an average pore diameter of 30μ.

Approximately 300 pieces were bundled together to make a filter chip with a diameter of 6 inches, and the tip was inserted into the conduit section of the pipe.

A commercially available double-cut piece was connected to a pipe and a smoke test was conducted.

When suction resistance is 240mmH2O, nicotine adsorption rate is 31%
The tar adsorption rate was 34%, and the polyphenol adsorption rate was 58%.

In addition, as a result of a sensory test, 95% of 20 smokers agreed that it eased the smoking taste.

This porous fiber was found to be non-oriented in an X-ray diffraction photograph, with no diffraction rings exhibiting crystallinity, and only a non-quality halo.

Example 2 50 g of aluminum chloride dihydrate was dissolved in 100 g of methanol, and 3 g of nylon 6 chips and 12 g of cellulose diacetate were mixed and dissolved.

It was 750 poise at 25°C.

After degassing under reduced pressure, a spinneret of 0.25 gmφ, 5
Wet spinning was carried out under the same conditions as in Example 1 using 0 holes.

The obtained porous fiber had a single fiber diameter of 300μ and a porosity of 70.
It had through-holes with an average pore diameter of 30 μm.

Approximately 100 pieces were bundled together to make a filter chip with a diameter of 61 LTIL, which was inserted into the conduit section of the pipe.

As a result of the same smoke test as in Example 1, the nicotine adsorption rate was 3.
Section 6, tar adsorption rate 40%, polyphenol adsorption rate 55
It was a rice cake.

Also, as a result of a sensory test, 90% of people agreed that the taste was milder.

As a result of the X-ray diffraction photograph, only a non-oriented halo was observed.

Example 3 A nylon-cellulose acetate solution prepared with the composition of Example 1 was prepared using a spinneret Q with a hole of 100 nm in diameter and 25 mm in diameter.
Wet spinning was carried out in a 3-diluted hydrochloric acid aqueous solution at .degree.

Table 1 shows the draft value and the performance of the obtained porous fiber.

These porous bodies No. 3-1 to 3-6 had through holes of 20 to 40 μm, and had good air flow passage performance.
Differences in adsorption to harmful substances were observed with a draft value of 1.0 as the boundary.

That is, by having crystallinity and orientation, the adsorption rate of polyphenols in particular decreases.

Comparative Area 1 In the same manner as in Example 1, 50 g of calcium chloride dihydrate was dissolved in 100 g of methyl alcohol, and 5 g of nylon 6 chips and 10 g of cellulose acetate were mixed and dissolved.

After defoaming under reduced pressure, it was cast onto a glass plate and coagulated with a 3-dilute hydrochloric acid aqueous solution to obtain a film-like porous body with a thickness of 130 μm.

As a result of X-ray diffraction, it was found to be defective and the molecular chains were non-oriented.

When the cross section in the direction perpendicular and parallel to the film surface was observed under a microscope, only flat pores were present and no through-holes were present.

In the case of a porous film made by the solvent casting method, it does not have through holes as described above.

Therefore, since cigarette smoke does not pass through the inside of the porous filter, only the surface of the porous material has an adsorption effect. Therefore, an adsorption effect equivalent to that of the porous filter with through holes of the present invention is sought. In order to achieve this, it is necessary to increase the surface area, which naturally results in an increase in filter volume and filter weight, and when used as a cigarette filter, it is significantly inferior to the porous body with through holes of the present invention. It is clear that there are.

Comparative Example 2 50 g of calcium chloride dihydrate was mixed with 100 g of methyl alcohol.
g, and 15 g of cellulose acetate was mixed and dissolved therein.

The viscosity at 25°C was 950 poise.

After degassing under reduced pressure, use a spinneret with a diameter of 0.01 mm, 10
Using a 0 hole, draft o, s into a coagulation bath prepared with a 3% dilute aqueous hydrochloric acid solution at 25°C.

Wet spinning was performed.

The obtained porous fiber had a single thread of 150μ, a porosity of 60,
It had through-holes with an average pore diameter of 25 μm.

A suction test was conducted in the same manner as in Example 1, and the result was that the nicotine adsorption rate was 28%, the tar adsorption rate was 30%, and the polyphenol adsorption rate was 7%.

Comparative Example 3 A tow of cellulose acetate fiber of 7 d of single yarn and a tow of nylon 6 fiber of 7 d of single yarn were mixed in a weight ratio of 1:1, and the tow of 6 d of single yarn was mixed without using any adhesive or swelling agent. A filter chip was made and inserted into the conduit section of the pipe.

As a result of the smoke test, the nicotine adsorption rate was 24%, the tar adsorption rate was 27%, and the polyphenol adsorption rate was 20%.

As a result of the sensory test, 55% of people agreed that the taste was the same as that of the conventional filter tip made only of cellulose acetate tow.

As is clear from the above examples, the present invention has an extremely superior effect on adsorbing harmful substances compared to conventional cigarette filters, and is porous but has through-holes, so it It has low smoke absorption resistance and excellent adsorption properties despite the small amount of filter, making it an extremely excellent cigarette filter.

Claims (1)

[Claims] 1. Polyamide and cellulose acetate with an acetylation degree of 53 to 58 are dispersed and substantially integrated in a finely mixed state of 1 μm or less with almost no orientation. a porous body with a porosity of 30 to 80 cm, the porous body having an average pore diameter of 0.1 μ to 1 mm, the orientation angle of the long axis of which is substantially perpendicular to at least one coordinate axis; A porous body for a cigarette filter, characterized by having through holes. 2 The mixing ratio of polyamide and cellulose acetate is 5 to 6
0:95-40. The porous body for cigarette filters according to claim 1. 3. The porous body for a cigarette filter according to claim 1, wherein the porous body has a porosity of 50 to 70%. 4. The porous body for a cigarette filter according to claim 1, wherein the average pore diameter of the through holes is 20 to 200 mμ. 5. The porous body for a cigarette filter according to claim 1, wherein the orientation angle of the long axis of the through hole is substantially perpendicular to two orthogonal coordinate axes. 6 Both components of polyamide and cellulose acetate with an acetylation degree of 53 to 58 are mixed in a solution of an aliphatic primary alcohol having 4 or less carbon atoms containing an alcohol-soluble deliquescent inorganic compound, and mixed with 20 weights of 8-fold or more heredity. Below, a porous cigarette filter characterized in that the inorganic compound is dissolved and then wet-spun into an aqueous coagulation bath at a draft of less than 1.0, and the inorganic compound is simultaneously dissolved and removed, or removed by washing after wet-spinning. How the body is manufactured. 7 The mixing ratio of polyamide and cellulose acetate is 5 to
60:95-40, the method for producing a porous body for a cigarette filter according to claim 6. 8. Claim 6, wherein the alcohol-soluble deliquescent inorganic compound is at least one selected from the group of calcium chloride, lithium chloride, aluminum chloride, magnesium chloride, calcium nitrate, lithium nitrate, and aluminum nitrate. A method for producing a porous material for cigarette filters. 9. The method for producing a porous body for a cigarette filter according to claim 6, wherein the aqueous coagulation bath is a dilute aqueous hydrochloric acid solution or an aqueous phosphoric acid solution. 10. The method for producing a porous body for a cigarette filter according to claim 6, wherein the temperature of the aqueous coagulation bath is 5 to 35°C.