JP3208403B2 - Biodegradable nonwoven fabric and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a biodegradable product,
In addition, the present invention relates to a non-woven fabric having microbial degradability and a method for producing the same, which can be suitably used as a material for disposable general living materials represented by sanitary materials, wipes, packaging materials and the like.

[0002]

2. Description of the Related Art Conventionally, nonwoven fabrics have been widely used as materials for sanitary materials, general living materials, industrial materials and the like. Examples of the fiber material constituting the nonwoven fabric include polymers such as polyethylene, polypropylene, polyester, and polyamide. However, nonwoven fabrics made of these materials have no self-decomposability and are chemically very stable under ordinary natural environments. Accordingly, at present, disposable nonwoven fabrics are treated by incineration or landfill after use. Although incineration is widely practiced in Japan, it requires a great deal of cost and is causing pollution from waste plastics.How to solve this problem of disposal of waste plastics, It is a major social issue in terms of protection of the natural environment and living environment. On the other hand, with regard to landfill, there is a problem that the material remains chemically stable for a long time in soil because the material is chemically stable.

As a method for solving such a problem, a new nonwoven fabric which is naturally degraded in a short period of time by using a material having natural degradability (microbial degradability, biodegradability) is demanded. .

[0004] Generally, the fibers having microbial degradability include cellulosic fibers such as cotton and hemp, and protein fibers such as silk. However, because these so-called natural fibers are non-thermoplastic,
When fabricating a nonwoven fabric using these fibers, a so-called embossing method or a thermal bonding method in which the fibers are thermally bonded to form a nonwoven fabric cannot be employed. In addition, it is not decomposed in a short time, the nonwoven fabric form is maintained for a long time,
It is not preferable in terms of protection of the natural environment and living environment.

[0005] Microbial degradable polymers include polysaccharides such as chitin, proteins and polypeptides (polyamino acids) such as cut gut (intestinal tract) and regenerated collagen, and poly-3-hydroxybutyrate produced by microorganisms in nature. And microbial polyesters such as poly-3-hydroxyvalerate and poly-3-hydroxycaprolate; synthetic aliphatic polyesters such as polyglycolide and polylactide;
Etc. are well known. However, when producing fibers from these polymers, there is a restriction that it is necessary to use a wet spinning method. Also, due to the extremely high cost of the material, its application is limited to fields such as bioabsorbable sutures.

[0006] Recently, as a biodegradable film, a mixture of polyethylene and starch has been proposed, and the film is used as a material for shopping bags. However, since polyethylene will not be decomposed in the future, it cannot be said to be a biodegradable film in its original sense. Moreover, it is not easy to obtain fibers suitable for use in nonwoven fabrics, and at present, starch-containing fibers for nonwoven fabrics have not been obtained.

[0007]

SUMMARY OF THE INVENTION In view of the above background, the present invention provides an inexpensive nonwoven fabric which can be easily decomposed by microorganisms and has high flexibility and is inexpensive.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a biodegradable nonwoven fabric of the present invention comprises a polymer consisting of only poly-ε-caprolactone, poly-β
And a mixture of a polymer consisting of only poly-ε-caprolactone and a polymer consisting of only poly-β-propiolactone, and having a single-fiber fineness of 0.1. It is composed of 8 to 6 denier fiber , and is further subjected to thermocompression bonding by embossing roll.
It is characterized by having.

Hereinafter, the present invention will be described in detail. The poly-ε-caprolactone (hereinafter may be referred to as “PCL”) and / or poly-β-propiolactone (hereinafter may be referred to as “PPL”) is AS
The melt flow rate (g / 10 minutes) measured according to TM-D-1238 (E) is 45 or less, preferably 30 or less. When the melt flow rate exceeds 45, the strength of the obtained fiber is low, and as a result, the strength of the nonwoven fabric is undesirably low.

The fibers constituting the nonwoven fabric of the present invention have a single-fiber fineness of 0.8 to 6 deniers. The reason for limiting to 0.8 to 6 deniers is that disposable diapers and covers for sanitary products are used. This is for the purpose of providing a soft texture that can be applied to a stock or a wipe. If the single-fiber fineness exceeds 6 denier, the texture becomes a rough non-woven fabric, which is not preferable. If the single-fiber fineness is less than 0.8 denier, the spinnability deteriorates, which is not preferable.

The nonwoven fabric of the present invention has a basis weight of 10 to 150 g.
/ M ² , particularly preferably 10 to 100 g / m ² . If the basis weight exceeds 150 g / m ² , a soft nonwoven fabric cannot be obtained. In particular, in the case of a nonwoven fabric that does not require durability, it is preferable to set the basis weight to 100 g / m ² or less because the nonwoven fabric becomes more flexible. A nonwoven fabric having a basis weight of less than 10 g / m ² is not only difficult to produce, but also has poor uniformity of the nonwoven fabric itself, which is not preferable.

Next, the production method of the present invention will be described. Nonwoven fabrics can be produced by two methods. First, there is a so-called spunbond method. In this method, poly-ε is used.
Any one of a polymer consisting of only caprolactone, a polymer consisting of only poly-β-propiolactone, a polymer consisting of only poly-ε-caprolactone and a polymer consisting of only poly-β-propiolactone The fiber is melt-spun through a spinneret at a temperature 100 to 240 ° C. higher than the melting point, and the spun filaments are cooled and solidified, and then the air soccer is disposed at least 100 cm below the spinneret. 2000m by taking over means such as
After drawing / drawing at a suction / pulling speed of / min or more, and subsequently opening the long fiber group, a web having a single fiber fineness of 0.8 to 6 denier long fibers is obtained.

Second, there is a so-called spin draw spunbond method. In this method, a polymer consisting of only poly-ε-caprolactone, a polymer consisting of only poly-β-propiolactone, and a polymer consisting of only poly-ε-caprolactone are provided. Of a polymer consisting of a polymer consisting of only poly-β-propiolactone and a polymer consisting of
The melt spun at a high temperature of from 00 to 240 ° C., and the spun long fiber group is cooled and solidified, and then taken out at a take-up speed of 500 m / min or more. Between 1.5 and 3.5 times, followed by a web having a single-fiber fineness of 0.8 to 6 denier long fibers.

When a nonwoven fabric is manufactured by the spunbond method, the take-off means is arranged at least one position from the spinneret when the take-up means is taken up by take-up means such as air soccer.
Must be below 00cm. If the distance is shorter than this distance, adhesion occurs between the single yarns and spinning cannot be performed. Then, traction and take-off are performed so that the take-up speed becomes 2000 m / min or more. When the speed is lower than this speed, the degree of orientation of the obtained long fiber is low, and therefore, the strength is low and the strength of the nonwoven fabric is inferior. The group of long fibers thus obtained is collected and deposited on a moving endless net to form a web, and the web is heated between the long fibers.
The non-woven fabric can be manufactured by thermocompression bonding using a boss roll .

In the case of producing a nonwoven fabric by the spin draw spunbond method, the spun long fiber group is taken up by a take-up roll, and stretched between the take-up roll and a subsequently provided stretching roll. As the stretching method, one stage or two or more stages of cold stretching or hot stretching are employed. In the case of PCL, normal temperature stretching may be used, and in the case of PPL or PCL and PP.
In the case of mixing L, heat stretching may be performed at 40 to 60 ° C. Then, the fiber is drawn at a speed of 500 m / min or more and stretched at a total draw ratio of 1.5 to 3.5 times, whereby a fiber having a tensile strength of 2.5 g / denier or more can be produced. This method is particularly suitable when a high-viscosity polymer is used.

The cross-sectional shape of the fiber is not limited to a round shape, but may be any shape such as a hollow shape, a flat shape, and a Y shape according to the application.

[0017]

The nonwoven fabric of the present invention thus obtained has good microbial degradability, is flexible, has sufficient strength to withstand practical use, and is used as a cover stock for disposable diapers and sanitary articles, a wipe cloth, and the like. Applicable to

[0018]

The present invention will be described below in more detail with reference to examples. PCL and / or P applied to each embodiment
PL melt flow rate (hereinafter referred to as "MFR")
Was measured according to ASTM-D-1238 (E).
The melting point was measured at a heating rate of 20 ° C./min using a DSC-7 type device manufactured by PerkinElmer. When measuring the tensile strength of the nonwoven fabric shown in the examples, JIS-L-10
According to the strip method described in 96, width 3 cm, length 10
The maximum tensile strength was measured using a 10 cm / cm test piece at a tensile speed of 10 cm / min. The initial tensile strength shown in each example was calculated from the following formula after measuring the basis weight for comparison in terms of the basis weight of 30 g / m ² .

Initial tensile strength (g / 3 cm) = 30 × tensile strength (g) / basis weight (g / m ² ) The flexibility of the nonwoven fabric was represented by the compression bending resistance. When measuring compression bending resistance, width (vertical direction) 5 cm, length (horizontal direction)
A 10 cm test piece was bent laterally into a cylindrical shape, and its end was joined to form a sample. Then, using a device of Toyo Baldwin Co., Ltd. Tensilon UTM-4-100, 5 cm /
The cylindrical sample was compressed longitudinally at a compression rate of 1 minute. The compression stiffness is a value obtained by measuring the stress at the maximum load at that time. The smaller the value, the better the flexibility. At the time of evaluation, if the compression bristles were 70 g or more, the overall evaluation was poor.

Regarding the evaluation of microbial degradability, the nonwoven fabric was buried in the soil for three months and then taken out. The nonwoven fabric did not maintain its shape, or the tensile strength was reduced to 50% or less of the initial value even if the shape was maintained. In the case where it was carried out, it was judged that the microbial degradability was good. Even when the microbial decomposability is good, when the initial tensile strength (basis weight: 30 g / m ² conversion value) of the nonwoven fabric is less than 1000 g / 3 cm, the overall evaluation is poor. Example 1 Using PCL having a melting point of 59 ° C. and an MFR of 25 g / 10 min, a plurality of spinneret packs having a hole diameter of 0.35 mm and 84 holes were used and melt-spun at a spinning temperature of 230 ° C. The spun long fiber group was pulled and pulled at various suction and pulling speeds while changing the air pressure using an air sucker placed 150 cm below the spinneret. A long fiber group is spread, collected, and deposited on a moving endless wire mesh to form a web, and then, using a heated metal embossing roll and a metal flat roll, a linear pressure of 40 kg / cm and a pressing area ratio of 17%. , Heat-treated at a heat treatment temperature of 57 ° C, and a basis weight of 30 g
/ M ² . Table 1
The discharge amount of the polymer was adjusted so as to obtain the long fibers having the single-filament fineness shown in (1). Table 1 shows the evaluation results of the strength, compression bristles and microbial degradability of each of the obtained nonwoven fabrics.

[0021]

[Table 1]

As is evident from Table 1, Nos. 1 to 3 of the examples of the present invention exhibited good strength, compressive softness and microbial degradability of the obtained nonwoven fabric. However, No. 4 having too high a single-fiber fineness was poor in texture and could only obtain a non-woven fabric having a rough and hard texture. Comparative Example 1 The spinning temperature was set to 230 ° C., the position of the air sucker was set to 80 cm below the spinneret, and the spinning was performed at 3500 m / min in the same manner as in Example 1. However, adhesion occurred between the long fibers, and a nonwoven fabric could not be obtained. Example 2 Using PPL having a melting point of 101 ° C. and an MFR of 25 g / 10 min, using a plurality of spinneret packs having a hole diameter of 0.35 mm and 84 holes, and melt-spinning at a spinning temperature of 250 ° C. Taken at the indicated speed. Next, the film was stretched at a stretching ratio shown in Table 2 at a temperature of 50 ° C. At this time, the discharge amount of the polymer was adjusted so as to obtain a single fiber fineness of 4 denier long fiber. Then, open a long fiber group on a moving endless wire mesh.
The web was collected and deposited. Thereafter, a linear pressure of 4 mm was applied using a heated metal embossing roll and a metal flat roll.
Heat treatment was performed at 0 kg / cm, a pressure contact area ratio of 17%, and a heat treatment temperature of 95 ° C. to obtain a spunbond nonwoven fabric having a basis weight of 30 g / m ² . Table 2 shows the strength and compression stiffness of each nonwoven fabric.

[0023]

[Table 2]

As is clear from Table 2, Nos. 2 and 3, which are examples of the present invention, had good strength and microbial degradability of the obtained nonwoven fabric, and had a soft texture. Example 3 PCL with MFR of 20 g / 10 min and MFR of 25 g / 1
A PPL of 0 min is mixed in a chip form at a weight ratio of 50/50, a plurality of spinneret packs having a hole diameter of 0.35 mm and 84 holes are used, and a discharge rate of 1.5 g / min / hole is used. The melt was spun at a spinning temperature of 250 ° C. 150 under the spinneret
Using an air sucker, the spun long fiber group was drawn and drawn at a suction / draw speed of 3500 m / min to obtain a long fiber having a single-filament fineness of 4 denier. A long fiber group is spread, collected, and deposited on a moving endless wire mesh to form a web, and then, using a heated metal embossing roll and a metal flat roll, a linear pressure of 40 kg / cm and a pressing area ratio of 17%. A heat treatment was performed at a heat treatment temperature of 60 ° C. to obtain a spunbond nonwoven fabric having a basis weight of 30 g / m ² . The resulting nonwoven fabric has a strength of 2480 g / 3 cm and a compression stiffness of 33.
g, and the microbial degradability was good.

[0025]

As described above, according to the present invention, a nonwoven fabric having a tensile strength and a soft hand that can withstand practical use and having microbial degradability can be prepared by a spunbond method, a spin draw spunbond method, or the like. Can be obtained inexpensively by the simple method described above. Further, the nonwoven fabric of the present invention is suitable as a material for general living materials such as sanitary materials, wipes, packaging materials,
If left in an environment where microorganisms are present after use, it will be biodegraded, so no special waste treatment is required, and it is extremely useful from the global environmental conservation point of view.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Takashi Inoue 222-1203 Imai Nishimachi, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture (56) References JP-A-5-195407 (JP, A) JP-A-2-119866 ( JP, A) JP-A-3-146754 (JP, A) JP-A-4-50353 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) D04H 1/00-18/00 EPAT (QUESTEL) WPI / L (QUESTEL)

Claims (3)

(57) [Claims] 1. A polymer consisting only of poly-.epsilon.-caprolactone, a polymer consisting only of poly-.beta.-propiolactone, a polymer consisting of only poly-.epsilon.-caprolactone and only consisting of poly-.beta.-propiolactone. It is composed of fibers having a single-fiber fineness of 0.8 to 6 denier, and is further formed by embossing rolls.
A microbial degradable nonwoven fabric characterized by being subjected to thermocompression bonding . 2. A polymer consisting only of poly-.epsilon.-caprolactone, a polymer consisting only of poly-.beta.-propiolactone, a polymer consisting only of poly-.epsilon.-caprolactone and only consisting of poly-.beta.-propiolactone. Either of the mixture with the polymer is passed through a spinneret from the melting point to 100 to 240.
After melt-spun at a high temperature and cooling and solidifying the spun long fiber group, it is suctioned at a rate of 2,000 m / min or more by a take-off means such as an air soccer disposed at least 100 cm below the spinneret. Pulling and pulling at the pulling speed, followed by opening the long fiber group, and then the single fiber fineness is set to 0.
A web composed of 8 to 6 denier long fibers ,
Use a heated embossing roll and flat roll
And subjecting the same to thermocompression bonding . 3. A polymer consisting only of poly-.epsilon.-caprolactone, a polymer consisting only of poly-.beta.-propiolactone, a polymer consisting only of poly-.epsilon.-caprolactone and only consisting of poly-.beta.-propiolactone. Either of the mixture with the polymer is passed through a spinneret from the melting point to 100 to 240.
C., melt-spun at a high temperature, cool and solidify the spun long fiber group, take it off at a take-up speed of 500 m / min or more, and further take it out with a take-up roll and a drawing roll provided subsequently. The web is stretched 1.5 to 3.5 times , and then the web is formed from long fibers having a single fiber fineness of 0.8 to 6 denier.
A method for producing a microbial-degradable nonwoven fabric, comprising performing thermocompression bonding using a non-woven fabric.