US3890983A

US3890983A - Method for preparing cigarette filter

Info

Publication number: US3890983A
Application number: US389083A
Authority: US
Inventors: Hideo Sawada; Junji Kawamoto
Original assignee: Daicel Corp
Current assignee: Daicel Corp
Priority date: 1973-08-22
Filing date: 1973-08-22
Publication date: 1975-06-24
Anticipated expiration: 1992-06-24

Abstract

A method for preparing a cigarette filter of cellulose acetate fibers is provided, which is characterized by blooming a tow composed of cellulose acetate fibers, adding to the bloomed tow 1 to 20% by weight (based on the cellulose acetate fibers) of a plasticizer comprising as an ingredient a diglycerol ester compound and gathering the thus treated bloomed tow.

Description

United States Patent 11 1 Sawada et a1.

METHOD FOR PREPARING CIGARETTE FILTER Inventors: Hideo Sawada; Jul ii Kawamoto, both of Sakai, Japan Assignee: Daicel, Ltd., Osaka, Japan Filed: Aug. 22, 1973 Appl. No.: 389,083

US. Cl. 131/267; 156/180; 156/307 Int. Cl A2411 15/02 Field of Search 156/180, 307; 131/267; 260/488 1 References Cited UNITED STATES PATENTS 11/1961 Touey et al 131/208 June 24, 1975 3,017,309 1/1962 Crawford et a1 156/161 3,043,736 7/1962 Touey 1. 156/152 3,451,887 6/1969 Toucy et a1 161/168 Primary Examiner-Daniel J. Fritsch Attorney, Agent, or FirmWoodhams, Blanchard and Flynn [5 7] ABSTRACT 7 Claims, No Drawings 1 METHOD FOR PREPARING CIGARETTE FILTER This invention relates to a method for preparing a cigarette filter. More particularly, the invention relates to a method for preparing a cigarette filter which comprises adding a plasticizer containing as an ingredient a diglycerine ester compound to cellulose acetate fibers.

Tobacco smoke filters are very important in the cigarette manufacturing industry, because they exhibit excellent effects in removing harmful substances from tobacco smoke and, therefore, the demand for tobacco smoke filters is increasing year by year. However, the requirements for a satisfactory cigarette filter tip are becoming more stringent and improvements in the quality of cigarette filters are strongly desired.

In general, triacetin is used most widely in the industry as a plasticizer for cellulose acetate fibers constituting cigarette filters. However, triacetin has a relatively low boiling point (258C at 760 mmHg) and, though it is substantially not volatile at room temperature, triacetin may be released from filters when filter cigarettes are smoked and it will give a bitter taste in smoking. Thus, it is insufficient with respect to the cigarette flavor and smoking taste.

Further, diacetate, dipropionate and dibutyrate esters of polyethylene glycol are also used as plasticizers for cellulose acetate fibers constituting cigarette filters. However, cigarette filters obtained by using these plasticizers are defective in that the plasticizing effects of such compounds are too strong, thereby causing unnecessary dissolution of cellulose acetate fibers and also they are still unsufficient in cigarette flavor and smoking taste.

Dimethoxyethyl phthalate and triethyl citrate are also used as plasticizers, but, when they are used, it is necessary to heat filter rods at high temperatures exceeding room temperature for 2 to 4 hours during the step of curing the rods. Further, the obtained filters are generally not good with respect to the cigarette flavor and smoking taste.

We have studied to obtain a cigarette filter for tobacco smoking which does not cause any harm to the flavor and smoking taste and achieved the method of the present invention.

That is, we have discovered that, when a plasticizer containing as an ingredient a diglycerol ester compound is employed according to this invention a cigarette filter which does not harm the flavor and smoking taste of cigarettes can be obtained and have now completed this invention based on this finding.

Diglycerol ester compounds to be used in this inven tion are preferably acetate and propionate esters of diglycerol obtained by condensation and dehydration from two molecules of glycerol. These esters are tetraesters, triesters, diesters or mixtures thereof, which can be represented by the following general formula:

wherein R stands for hydrogen or a lower alkyl group having one tofour carbon atoms, preferably l to 2 carbon atoms, and whereas at least two R should be such lower alkyl groups.

These compounds can be used singly or in combination with another plasticizer. For example, they can be used together with triacetin, triethyleneglycol diacetate, etc. at an optional ratio.

In this invention, the plasticizer is added in an amount of l to 20% by weight (all percent values given hereinafter are on the weight basis), especially 5 to 10%, based on the cellulose acetate fibers.

In this invention, cellulose acetate fibers are used in the form of a tow obtained by gathering 5,000 to 100,000 continuous fibers having a size of l to lo deniers. It is preferred that 10 to 30 uniform crimps are given to the tow per 25 mm of the tow length.

Any method that can apply the plasticizer uniformly to cellulose acetate fibers may be adopted in this invention without any particular limitation. For instance, the plasticizer is applied to both the upper and lower surfaces of the tow by a known method using a spray gun or wick. In case the amount of the plasticizer is too large locally, cellulose acetate fibers are so dissolved that dopes are formed. Accordingly, it is desired that the plasticizer is applied uniformly. in case the amount of the plasticizer is too small, a sufficient bonding is not obtained among the fibers. In view of the foregoing, in this invention it is important that the plasticizer is distributed uniformly in the interior of the tow band.

In this invention, the preparation of cigarette filters from plasticizer-containing tows can be conducted by methods now industrially conducted for the preparation of cigarette filters of cellulose acetate fibers.

The cigarette filter obtained by the above-mentioned method of this invention is characterized in that the inherent flavor and smoking taste of tobacco are not damaged at all and there can be obtained cigarette filters having satisfactory pressure drop hardness and other properties. Accordingly, this invention has a great industrial value.

The advantages of the method according to the present invention are summarized as follows:

1. The above diglycerol ester compounds have high boiling points, and they are odorless, colorless, tasteless and non-toxic. They have boiling points of to 230C at 3 mmHg which are higher than that of triacetin, and, therefore, there is no substantial possibility of their being inhaled into the mouth and, even if they might be inhaled, the taste and flavor of the filter cigarette will not be damaged.

2. The diglycerol ester compounds themselves are stable and substantially not hydrolyzable and, accordingly, they do not give any acidic smell.

3. They have sufficient plasticizing effects on cellulose acetate fibers at room temperature.

As mentioned above, the method by employing the above diglycerol ester compounds according to the present invention has many advantages in the manufacture of tobacco smoke filters and in the quality of the obtained cigarette filter per se and it will be apparent that the method of the present invention is much more efiective in comparison with known conventional methods.

The method of this invention will now be illustrated by reference to Examples. ln Examples, the rod hardness, pressure drop and nicotine and tar removal ratios were determined by the following methods, respectively. which have been conventionally employed in the art.

Hardness Pressure Drop It was expressed in terms of the resistance pressure in a water column height (mm) obtained when air was passed through a filter rod of a length of MD mm at a rate of 17.5 ml/sec.

Tar removal ratio and Nicotine removal ratio A sample filter tip was attached to a cigarette and the obtained filter cigarette was smoked, when the amounts of nicotine and tar contained in the smoke passed through the filter and the amounts of nicotine and tar adsorbed on the filter were respectively determined by ultraviolet spectroscope and gas chromatography. The respective ratios of nicotine and tar ad sorbed on the filter based on their entire amounts were shown by as nicotine and tar removal ratios.

EXAMPLE 1 A cellulose acetate fiber tow of a filament denier of 4 and a total denier of43,000 having 26 crimps per 25 mm of the tow length was bloomed and diglycerol tetraacetate was added in the amount of 4.7% by weight to the bloomed cellulose acetate fiber tow by means of a plasticizer applicator. Then, the tow was fed to a filter rod maker apparatus and wrapped by means of a rice paper. Then, it was cut into a length of lOZ mm.

Such filter characteristics as the rod weight, the pressure drop, the hardness of the rod and the removal raties of nicotine and tar were determined with respect to the resulting rod. The results are shown in Table 1.

For the purpose of comparison, the above procedure was repeated in the same manner by employing triacetin as the plasticizer in the amount of 8% by weight, and the properties of the resulting filter rod were determined in the same manner. The results are shown in Table l as results of Comparative Example l.

Each of the thus-obtained rods having a length of 102 mm was divided into 6 filter tips having a length of 17 mm. A tip of a commercially available Hi-Light cigerette (Trade name} was removed and the thus formed tip was attached instead. As a result of the smoking test, it was found that volatilization of the plasticizer is particularly small and a good taste and flavor was obtained in the case of the plasticizer comprising diglyc erol tetracetate without causing any harm to the taste in tobacco smoking.

EXAMPLE 2 Except that 6.5% by weight of a mixture of equal amounts of triacetin and diglycerol tetracetate was used instead of diglycerol tetraacetate alone as the plasticizer, a filter rod was produced substantially by the same procedure as in Example 1. The properties of the resulting filter rod were as follows:

Pressure Drop Hardness Rod weigh! When this filter tip was attached to the cigarette in the same manner as in Example 1, it gave a good taste in smoking.

EXAMPLE 3 Except that 7.0% by weight of a mixture of equal amounts of triethyleneglycol diacetate and diglycerol tetraacetate was used instead of diglycerol tetraacetate alone as the plasticizer, a filter rod was produced substantially by the same procedure as in Example 1.

Also, as Comparative Example 2, a filter rod was produced substantially by the same procedure as in Example 1, except that 6.9% by weight of triethyleneglycol diacetatc alone was used instead of diglycerol tetraacetate alone.

The properties of the filter rods obtained above in Example 3 (7.0 wt.% of a mixture of equal amounts of triethyleneglycol diacetate and diglycerol tetraacetate) and in Comparative Example 2 are shown in Table 2.

Further, as a result of the smoking test, it was found that the filter rod produced by using a plasticizer comprising diglycerol tetraacetate as an ingredient was excellent particularly in the taste and flavor in smoking, compared to the filter rod produced by using triethyleneglycol diacetate alone as the plasticizer.

What we claim is:

I. A tobacco smoke filter comprising a bundle of substantially longitudinally extending cellulose acetate fibers having a size of from 1 to 16 denier per fiber, said fibers being substantially uniformly coated with from I to 20% by weight, based on the weight of the fibers, of a plasticizer comprising as an ingredient a compound or a mixture of compounds having the formula:

cll ocore lYIlL OCUR wherein R is hydrogen or a lower alkyl group having one to four carbon atoms and at least two R are said lower alkyl groups.

5 6 2. A tobacco smoke filter according to claim 1, in wherein R is hydrogen or a lower alkyl group having which the amount of plasticizer is from 5 to l()% by one to four carbon atoms and at least two R are weight, based on the weight of the cellulose acetate fisaid lower alkyl groups, and gathering the thustreated bloomed tow to form a filter.

A method for p pf Cigarette f f Cellu' 4. A method according to claim 3, wherein said plaslose acetate fibers whch Comprises l t s a f" ticizer consists essentially of said ingredient. composed of cellulose acetate fibers, distributing uni- A method according to Claim 3 wherein Said p|as forlnly throughout the bloomed tow from I to 20% y ticizer contains at least 50% by weight of said ingrediweight, based on the cellulose acetate fibers, ofa plasticizer comprising as an ingredient a compound or a mix- 1() ture of compounds having the formula:

6. A method according to claim 5, wherein the remainder of said plasticizer is a substance selected from the group consisting of triacetin and the diacetate, dipropionate and dibutyrate esters of polyethylene glycol. aits-m li-lilil 7. A method according to claim 3, wherein the amount of said plasticizer is from S to 10%, based on the cellulose acetate fibers.

Claims

1. A TOBACCO SMOKE FILTER COMPRISING A BUNDLE OF SUBSTANTIALLY LONGITUDINALLY EXTENDING CELLULOSE ACETATE FIBERS HAVING A SIZE OF FROM 1 TO 16 DENIER PER FIBER, SAID FIBERS BEING SUBSTANTIALLY UNIFORMLY COATED WITH FROM 1 TO 20% BY WEIGHT, BASED ON THE WEIGHT OF THE FIBERS, OF A PLASTICIZER COMPRISING AS AN INGREDIENT A COMPOUND OR A MIXTURE OF COMPOUNDS HAVING THE FORMULA:

2. A tobacco smoke filter according to claim 1, in which the amount of plasticizer is from 5 to 10% by weight, based on the weight of the cellulose acetate fibers.

3. A method for preparing a cigarette filter of cellulose acetate fibers, which comprises blooming a tow composed of cellulose acetate fibers, distributing uniformly throughout the bloomed tow from 1 to 20% by weight, based on the cellulose acetate fibers, of a plasticizer comprising as an ingredient a compound or a mixture of compounds having the formula:

4. A method according to claim 3, wherein said plasticizer consists essentially of said ingredient.

5. A method according to claim 3, wherein said plasticizer contains at least 50% by weight of said ingredient.

6. A method according to claim 5, wherein the remainder of said plasticizer is a substance selected from the group consisting of triacetin and the diacetate, dipropionate and dibutyrate esters of polyethylene glycol.

7. A method according to claim 3, wherein the amount of said plasticizer is from 5 to 10%, based on the cellulose acetate fibers.