JP5157099B2 - Non-woven fabric for tea bags and tea bags - Google Patents

Description

  The present invention relates to a nonwoven fabric for tea bags made of thermoplastic filaments, and includes thermoplastic filaments made of a blend polymer of aliphatic polyester and polyamide.

  Conventionally, when extracting ingredients such as black tea, green tea, oolong tea, etc., a tea bag method is often used as a simple method. As a packaging material used for tea bags, paper is generally used in many cases, but there are problems such as poor strength and weakness, tearing of the paper and spilling tea leaves, and inability to heat seal processing.

  For example, Patent Document 1 describes in detail a technology related to a biodegradable monofilament for tea bags, which is made of poly-L-lactic acid, has a fineness of 15 to 35 dtex, and a boiling water shrinkage of 20% or less. Yes. According to this technique, a biodegradable monofilament for tea bags made of polylactic acid fiber that can be used as a tea bag can be obtained. Furthermore, since polylactic acid is used, disposal after use is easy, and furthermore, since non-petroleum-based raw materials can be used, it has the advantage of not increasing the absolute amount of carbon dioxide in the air. . However, when biodegradable monofilaments for tea bags made of polylactic acid fibers are used, the strength and elongation of nonwoven fabrics are often insufficient. There is a problem that powder leakage increases.

  For example, Patent Document 2 describes in detail a technology related to a tea bag using a polylactic acid polymer having a low melting point and a high melting point. According to this technique, it is possible to maintain a biodegradability of polylactic acid and to obtain a tea bag made of a fiber structure such as a complete circulation type biodegradable nonwoven fabric or a woven / knitted fabric. According to the technology, by using polylactic acid fibers having a low melting point and a high melting point, the fibers are bonded to each other by heat fusion, and a high-strength tea bag can be obtained. In addition, there is no description about heat shrinkage, and the non-woven fabric made of polylactic acid cannot obtain sufficient elongation, and since it contains a polylactic acid polymer having a low melting point, the heat shrinkage rate becomes high, and the tea bag is immersed in warm water. At this time, there is a problem that the taste of the extracted teas becomes thin due to shrinkage and tightness of the fabric, resulting in a slow extraction speed.

For example, Patent Document 3 describes in detail a technique in which a tea bag made of a non-woven fabric having excellent transparency can be obtained by adjusting the fiber diameter to be configured. According to the technique, a nonwoven fabric having excellent transparency and less powder leakage is obtained. However, there is no description about the elongation of the non-woven fabric, and if there is no elongation, the tea bag swells in warm water, so that the penetration and extraction of water into the tea leaves does not occur sufficiently, and the taste of the extracted teas There is a problem that becomes thin.
JP 2001-131826 A Japanese Patent No. 3462155 Japanese National Patent Publication No. 2004-003277

  In view of the above-mentioned problems of the prior art, the present invention contains, as a main component, a resin that is excellent in mechanical strength and dimensional stability and can be synthesized from non-petroleum raw materials such as aliphatic polyesters, particularly polylactic acid. Therefore, we intend to provide a non-woven fabric for tea bags that has a low environmental impact even when discarded.

The present invention employs the following means in order to solve such problems.
That is,
(1) A non-woven fabric for tea bags comprising a thermoplastic filament nonwoven fabric, wherein the thermoplastic filament comprises a blend polymer of polylactic acid and nylon 6 ,
The thermoplastic filament nonwoven fabric has both a vertical and horizontal heat shrinkage of -5 to + 10% after being immersed in boiling water for 5 minutes,
The single filament fineness of the thermoplastic filament is 1 to 15 dtex, the basis weight of the nonwoven fabric is 10 to 100 g / m ² , and the heat seal strength / elongation product per basis weight is 80 to 200,
The blend polymer of polylactic acid: the weight ratio of nylon 6 50:50 to 85:15,
A long-fiber non-woven fabric for tea bags, wherein nylon 6 component is finely dispersed with an average single fiber fineness of 1 × 10 ⁻⁷ to 1 × 10 ⁻³ dtex in the cross-sectional direction of the thermoplastic filament.

( 2 ) The long-fiber nonwoven fabric for tea bags according to (1) , wherein the fibers constituting the nonwoven fabric are heat-bonded to each other.

(3) (1) or tea bag made of long-fiber nonwoven fabric according to (2).

  ADVANTAGE OF THE INVENTION According to this invention, the nonwoven fabric for tea bags and a tea bag which have the outstanding mechanical strength and dimensional stability can be provided, including aliphatic polyester as one of the main components.

  The non-woven fabric for tea bags of the present invention is composed of a thermoplastic filament nonwoven fabric, and contains a thermoplastic filament composed of a blend polymer in which aliphatic polyester and polyamide are blended as the thermoplastic filament constituting the thermoplastic filament nonwoven fabric. Is.

  The aliphatic polyester is not particularly limited as long as it is a biodegradable aliphatic polyester. For example, polylactic acid, polyglycolic acid, polyhydroxybutyrate, polyhydroxybutyrate valerate, or a copolymer or modified product thereof. Can be used alone or in combination. Among them, a polylactic acid resin is most preferable because it has good spinnability and mechanical properties, and can be synthesized from plant-derived starch, and therefore has little environmental impact. As such a polylactic acid-based resin, poly (D-lactic acid), poly (L-lactic acid), a copolymer of D-lactic acid and L-lactic acid, or a blend thereof (including a stereo complex) is preferable. It is. The weight average molecular weight of the polylactic acid resin is preferably 50,000 to 300,000, more preferably 100,000 to 300,000. When the weight average molecular weight is less than 50,000, the strength of the fiber tends to be low, and when the weight average molecular weight exceeds 300,000, the spinnability of the polymer extruded from the nozzle is poor because the viscosity is high, It becomes difficult to draw at high speed, and ultimately it becomes an undrawn state, and there is a tendency that sufficient fiber strength cannot be obtained.

  Further, the aliphatic polyester used in the present invention is preferably one in which a part or all of the carboxyl groups at the molecular chain terminals are end-capped with a terminal blocking agent. When a part or all of the carboxyl groups at the end of the molecular chain of the aliphatic polyester are end-blocked, a decrease in strength of the filament and further the sheet due to hydrolysis is suppressed. The terminal carboxyl group concentration of the aliphatic polyester is preferably 0 to 20 equivalents / ton, more preferably 0 to 15 equivalents / ton, and more preferably 0 to 10 equivalents / ton by adding a terminal blocking agent. Is more preferable. Here, the carboxyl group end concentration of the aliphatic polyester was determined by dissolving a precisely weighed sample in o-cresol (5% water), adding an appropriate amount of dichloromethane to this solution, and then using 0.02 N KOH methanol solution. It can be determined by titration.

  The endblocker for the aliphatic polyester used in the present invention is not limited at all, but carbodiimide compounds and glycidyl-modified compounds having isocyanuric acid as a basic skeleton are preferable. The added amount of these end-capping agents is preferably in the range of 0.05 to 10 wt%, more preferably in the range of 0.1 to 7 wt% with respect to the aliphatic polyester.

Although it does not specifically limit as a carbodiimide compound used as a terminal blocker of aliphatic polyester in this invention, When a monocarbodiimide compound is used, 5% weight reduction temperature (henceforth T5 _% is shown. ) Is preferably a monocarbodiimide compound having a temperature of 170 ° C. or higher, and more preferably, T _5% is a monocarbodiimide compound having a temperature of 190 ° C. or higher. When T _5% of the monocarbodiimide compound is less than 170 ° C., the monocarbodiimide compound is decomposed and / or vaporized during spinning, which tends to increase yarn breakage and deteriorate product quality, which is not preferable. Furthermore, the monocarbodiimide compound is not preferable because it does not effectively react and act on the carboxyl group terminal of the aliphatic polyester and a sufficient effect of improving hydrolysis resistance cannot be obtained. Here, the 5% weight loss temperature is a sample weight of about 10 mg measured by a “TG-DTA2000S” TG-DTA measuring machine manufactured by MACSCIENCE, at a temperature rising rate of 10 ° C./min in a nitrogen atmosphere. This is the temperature obtained as the temperature when the weight is reduced by 5% with respect to the sample weight before the start of measurement.

  Examples of the monocarbodiimide compound that can be used as a terminal blocking agent in the present invention include, for example, N, N′-di-2,6-diisopropylphenylcarbodiimide, N, N′-di-2,6-di-tert. . -Butylphenylcarbodiimide, N, N'-di-2,6-diethylphenylcarbodiimide, N, N'-di-2-ethyl-6-isopropylphenylcarbodiimide, N, N'-di-2-isobutyl-6 Isopropylphenylcarbodiimide, N, N′-di-2,4,6-trimethylphenylcarbodiimide, N, N′-di-2,4,6-triisopropylphenylcarbodiimide, N, N′-di-2,4 Examples thereof include 6-triisobutylphenyl carbodiimide. The monocarbodiimide compound used as the end-capping agent may be a single type or a mixture of a plurality of types, but N, N in terms of heat resistance and reactivity and affinity with aliphatic polyesters. '-Di-2,6-diisopropylphenylcarbodiimide (hereinafter referred to as TIC) is preferable. When a plurality of types of monocarbodiimide compounds are used in combination, 50% or more of the total amount of monocarbodiimide compounds used as the end-capping agent is TIC. It is preferable that

  As a method of blocking the terminal carboxyl group with the monocarbodiimide compound, it can be obtained by reacting an appropriate amount of the monocarbodiimide compound as a terminal blocking agent in the molten state of the aliphatic polyester. From the viewpoint of suppressing low molecular weight substances, it is preferable to add and react the monocarbodiimide compound after completion of the polymerization reaction of the polymer. Examples of the mixing and reaction of the above-described monocarbodiimide compound and aliphatic polyester include, for example, a method of adding a monocarbodiimide compound to a molten aliphatic polyester immediately after the completion of the polycondensation reaction, stirring and reacting, and an aliphatic polyester chip. A method of adding and mixing a monocarbodiimide compound and then kneading and reacting with a reactor or an extruder, etc., a method of continuously adding a liquid monocarbodiimide compound to aliphatic polyester with an extruder, kneading and reacting, It can be carried out by a method of kneading and reacting a blend chip obtained by mixing a concentration-containing aliphatic polyester master chip and an aliphatic polyester homochip with an extruder or the like.

  The carbodiimide compound used as a hydrolysis inhibitor in the present invention is not particularly limited, but when a polycarbodiimide compound is used, [Chemical Formula 1]

4,4'-dicyclohexylmethane diisocyanate represented by the formula:

And isophorone diisocyanate represented by the formula:

It is preferably a polycarbodiimide compound derived from at least one tetramethylxylylene diisocyanate represented by the formula, having two or more carbodiimide groups in the molecule, and having the isocyanate terminal sealed with a carboxylic acid. .

  The polycarbodiimide compound is a 4,4′-dicyclohexylmethane diisocyanate (hereinafter abbreviated as HMDI) represented by the above formula 1, or an isophorone diisocyanate (hereinafter abbreviated as “IPDI”) represented by the above formula 2, or the above A carbodiimide derived from any one of tetramethylxylylene diisocyanate (hereinafter abbreviated as TMXDI) represented by Formula 3, or a carbodiimide derived from any mixture of the above compounds or any of the three mixtures. The main component is one having 2 or more carbodiimide groups in the molecule, preferably 5 or more carbodiimide groups. The upper limit of carbodiimide groups in polycarbodiimide is 20. Such a carbodiimide can be produced by a carbodiimidization reaction accompanied by a decarbonation reaction using HMDI, IPDI, TMXDI, a mixture of the above two compounds, or a mixture of the three compounds as a raw material. Of these, carbodiimide using 50% by weight or more of HMDI is preferable and carbodiimide using 80% by weight or more of HMDI is more preferable because the obtained fiber has excellent mechanical properties.

  In addition, as the polycarbodiimide compound used in the present invention, even if an unreacted polycarbodiimide compound is present in the aliphatic polyester resin, since it is excellent in thermal stability, the spinnability deteriorates when it is made into a filament. Since generation | occurrence | production of an irritating gas can be suppressed, it is necessary for the isocyanate terminal to be the terminal sealed using carboxylic acid. The carboxylic acid preferably used is a monocarboxylic acid, such as cyclohexane carboxylic acid, benzoic acid, trimellitic anhydride, 2-naphthoic acid, nicotinic acid, isonicotinic acid, 2-fluic acid, propionic acid, butyric acid, isobutyric acid, Examples include methacrylic acid, palmitic acid, stearic acid, oleic acid, cinnamic acid, glyceric acid, acetoacetic acid, benzylic acid, and anthranilic acid. Among these, cyclohexanecarboxylic acid is most preferred.

  In order to reduce the amount of pyrolysis gas generated by thermal degradation of the unreacted polycarbodiimide compound, the amount of polycarbodiimide compound added is equal to or less than twice the total carboxyl group terminal amount of the aliphatic polyester as the carbodiimide group equivalent. It is preferable to do. The addition amount of the polycarbodiimide compound is more preferably 1.5 times equivalent or less, more preferably 1.2 times equivalent or less of the total carboxyl group terminal amount.

  The glycidyl-modified compound having isocyanuric acid as a basic skeleton used as an endblocker for aliphatic polyesters in the present invention is represented by the following [Chemical Formula 4].

(Here, at least one of R _{1 to} R ₃ is a glycidyl ether or a glycidyl ester, and the rest are functional groups such as hydrogen, an alkyl group having 1 to 10 carbon atoms, a hydroxyl group, and an allyl group).
The glycidyl-modified compound having isocyanuric acid as a basic skeleton used as a terminal blocking agent in the present invention is not particularly limited as long as it is a compound represented by the above [Chemical Formula 4]. Any one of R ₁ to ₃ is a glycidyl group, the remaining two are allyl groups, diallyl monoglycidyl isocyanurate, or any _one of R _{1 to} R _{3 in} the above [Chemical Formula 4] is a glycidyl group. Monoallyl diglycidyl isocyanurate, one of which is an allyl group, and tris (2,3-epoxypropyl) isocyanurate in which all of R _{1 to} R _{3 in} the above [Chemical Formula 4] are glycidyl groups are preferably used. In addition, a crystal nucleating agent, a matting agent, a pigment, an antifungal agent, an antibacterial agent, a flame retardant, an antistatic agent, a hydrophilic agent, and the like may be added to the aliphatic polyester as long as the effects of the present invention are not impaired. .

In the present invention, nylon 6, nylon 66, nylon 6-10, nylon 12, or a copolymer or a modified product thereof can be used alone or blended as the polyamide constituting the blended polymer with the aliphatic polyester. . In selecting the polyamide, it is preferable to select a polyamide having a small melting point difference from the aliphatic polyester. In addition, a crystal nucleating agent, a matting agent, a pigment, an antifungal agent, an antibacterial agent, a flame retardant, an antistatic agent, a hydrophilic agent, and the like may be added to the polyamide as long as the effects of the present invention are not impaired.
The most preferred blend polymer in the present invention is one using the above-mentioned polylactic acid as the aliphatic polyester and nylon 6 as the polyamide. Nylon 6 is particularly preferable because it has a melting point of 220 ° C. and a melting point of 170 ° C. of polylactic acid is small, has high affinity, and has good spinnability when combined spinning. In particular, when used as a tea bag, a combination of the above polymers is a preferable form in terms of heat resistance because the melting point is 100 ° C. or higher, which is the boiling point of water.

  The weight ratio of aliphatic polyester: polyamide blended in the present invention is preferably in the range of 20:80 to 95: 5, more preferably 40:60 to 90:10, and most preferably 50:50 to 85:15. If the weight ratio of the polyamide exceeds 80, the effect of reducing the environmental impact by blending the aliphatic polyester is reduced, which is not preferable. If the weight ratio of the polyamide is 5 or more, the nonwoven fabric tends to have sufficient strength and heat shrinkage characteristics, which is preferable.

The thermoplastic filament made of the blend polymer in the present invention is preferably formed by finely dispersing polyamide in the cross-sectional direction at an average single fiber fineness of 1 × 10 ⁻⁷ to 1 × 10 ⁻³ dtex. If the average single fiber fineness of the polyamide is finely dispersed within the above range, the nonwoven fabric tends to have sufficient strength and heat shrinkage characteristics, which is preferable. The average single fiber fineness of the finely dispersed polyamide is more preferably 2 × 10 ^{−7 to} 5 × 10 ⁻⁴ dtex, and most preferably in the range of 9 × 10 ⁻⁷ to 4 × 10 ⁻⁴ dtex. In addition, the average single fiber fineness of the polyamide component in this invention is calculated | required with the following method. That is, 10 small sample samples are randomly collected from a sample, embedded in an epoxy resin, cut out as an ultrathin section in a cross-sectional direction, and 40,000 to 100,000 using a transmission electron microscope (TEM, for example, Hitachi H7100FA type). Take a photo at double magnification. The average value is calculated by measuring the size of the cross-sectional area of the polyamide component from each sample by 20 pieces in total, calculating a mean value, converting this to the fiber diameter of the circular fiber, and correcting the polymer density. is there. If it is difficult to distinguish between polyamide and aliphatic polyester in TEM observation, the sample may be appropriately stained.

In the present invention, as a method for finely dispersing the polyamide in the aliphatic polyester, it is preferable to knead by a melt kneading extruder, a stationary kneader or the like. In addition, as a method for improving kneadability, the combination of polyamide and aliphatic polyester is also important, and it is preferable to optimize the compatibility of the combined polymer. As a compatibility index, the difference in solubility parameter (SP value) between polyamide and aliphatic polyester is preferably 1 to 9 (MJ / m ³ ) ^1/2 . Here, the SP value is a parameter reflecting the cohesive strength of a substance defined by (evaporation energy / molar volume) ^1/2 . For example, “Plastic Data Book” Asahi Kasei Amidus Co., Ltd./Plastics Editorial Department, 189 It is described on the page. If the SP value difference between the polyamide and the aliphatic polyester is in the range of 1 to 9 (MJ / m ³ ) ^1/2 , the compatibility between the polymers will be improved, so that the dispersibility of the polyamide will be improved and the spinning stability will be improved. This is a preferable direction because the tendency to improve the property is also improved. For example, the above-mentioned combination of polylactic acid and nylon 6 has a difference in SP value of 2 (MJ / m ³ ) ^1/2 and is preferable from the viewpoint of compatibility.

  Furthermore, it is preferable that the melt viscosity of the polyamide is lower than that of the aliphatic polyester. It is preferable that the melt viscosity of the polyamide is lower than that of the aliphatic polyester because the polyamide is easily deformed by shearing force and easily dispersed.

  Although the said blend polymer is used as a raw material polymer of a thermoplastic filament nonwoven fabric, when manufacturing a thermoplastic filament nonwoven fabric by the spun bond method mentioned later, you may perform a blend and spinning continuously. Moreover, thermoplastic filaments other than the thermoplastic filament which consists of blend polymers may be included.

  The thermoplastic filament nonwoven fabric of the present invention preferably has a thermal shrinkage ratio in the vertical direction and the horizontal direction in the range of -5 to + 10% after being immersed in boiling water for 5 minutes. If the heat shrinkage is in the range of -10 to + 5% in both the vertical and horizontal directions, when used as a non-woven fabric for tea bags, the tea bag immersed in warm water shrinks, the basis weight becomes tight, and the extraction speed becomes slow. Therefore, it is possible to prevent the taste of the extracted tea from becoming thin, which is preferable. A more preferable range of the heat shrinkage rate is in the range of −3 to + 8%. A more preferable range of heat shrinkage is −2 to + 5%. In addition, the thermal contraction rate in this invention can be measured with the following method. That is, referring to JIS L1906 (2000 version) 5.9.1 and 5.9.2, 10 samples of 25 cm long x 25 cm wide were taken from any part of the non-woven fabric, and 20 cm in 3 vertical and horizontal positions. Is marked (measured to the nearest 0.01 cm) and immersed in boiling water for 5 minutes in a suitable container. Remove the test piece, drain lightly with a filter paper, etc., and remove the unnatural wrinkle without twisting or stretching, and let it dry on a flat screen with a horizontal screen mesh or similar hole. For 10 samples, measure the length of 3 marked vertical and horizontal directions to 0.01 cm units, apply the total of 10 samples to the following formula, and round off the first decimal place. Calculate heat shrinkage.

Thermal contraction rate (%) = ((L1-L2) / L1) × 100
Here, L1: Total length of three wires before heating (total of 10 samples) (cm)
L2: Total length of three wires after heating (total of 10 samples) (cm).

  Moreover, it is preferable that the single fiber fineness of the thermoplastic filament which consists of a blend polymer in this invention is 1-15 dtex. When the single fiber fineness of the filament is less than 1 dtex, when the tea bag is immersed in warm water, the taste of the extracted teas becomes unfavorable due to the slow extraction speed. When the single fiber fineness of the filament exceeds 15 dtex, it is not preferable because tea leaves and tea powder in the tea bag spill out. A more preferable range of single fiber fineness is 1.8 to 12 dtex. In addition, the single fiber fineness referred to here is a sample of 10 small pieces taken at random from a sample, photographed 500 to 3000 times with a scanning electron microscope or the like, and 10 fibers from each sample, a total of 100 fibers. The fiber diameter calculated by rounding off the average of those values and rounding to the nearest 0.01 μm is corrected with the density of the polymer, and the first decimal place is rounded off. Furthermore, the cross-sectional shape of the filament is not limited at all, and a round shape, an oval shape, a hollow round shape, a flat shape, or an irregular shape such as an X shape, a Y shape, or a multileaf shape is preferably used. However, the round shape is the most preferable because it is easy to manufacture.

The basis weight of the thermoplastic filament nonwoven fabric in the present invention is preferably 10 to 100 g / m ² . When the basis weight is less than 10 g / m ² , it is difficult to obtain sufficient strength for use as a non-woven fabric for tea bags, and when the basis weight exceeds 100 g / m ² , when the tea bag is immersed in warm water, The taste of the extracted teas becomes light due to the slow extraction speed, which is not preferable. More preferably, the nonwoven fabric has a basis weight of 15 to 70 g / m ² , and more preferably 20 to 50 g / m ² . Here, the basis weight is obtained by the following method. In other words, three samples with a size of 50 cm in length x 50 cm in width are taken and each weight is measured, and the average value of the obtained values is converted per unit area and calculated by rounding off the first decimal place. It is.

  The thermoplastic filament nonwoven fabric in the present invention is preferably used as a tea bag after being processed into a bag shape such as a flat bag or a tetrahedron and filled with an extractable substance. The bag-making method is not particularly limited, and for example, heat sealing, welding seal, fusing seal, ultrasonic sealing with an ultrasonic sewing machine, high-frequency sealing, etc. are possible by melting a nonwoven fabric with a heat sealer and bonding fibers together. Yes, a known bag making machine can be used. The temperature at the time of heat sealing is preferably within a range 15 ° C. lower than the melting point of the resin constituting the nonwoven fabric. If the temperature at the time of heat sealing is higher than the melting point of the resin constituting the nonwoven fabric, the nonwoven fabric is completely melted and there is a hole, which is not preferable. On the other hand, when the temperature is lower than the melting point by 15 ° C. or more, heat sealing is not sufficiently performed and peeling occurs at the bonded portion, which is not preferable. The time and pressure at the time of heat sealing can be performed under arbitrary conditions as long as they are within the above temperature range. The set temperature when the resin constituting the nonwoven fabric is composed of multiple components is set based on the resin having the lowest melting point. Further, when used as a tea bag, it is preferable that the heat seal strength / elongation product per basis weight is 80 to 200 in order to prevent the bonded portion from being broken and the tea leaves inside from spilling out. If the heat seal strength / elongation product per unit weight is less than 80, the strength of the heat seal portion tends to be insufficient, which is not preferable. When the heat seal strength / elongation product per basis weight exceeds 200, the texture of the nonwoven fabric tends to be too hard, which is not preferable. A more preferable heat seal strength / elongation product per basis weight is in the range of 100 to 180. The heat seal strength / elongation product per unit weight of the nonwoven fabric in the present invention indicates the relationship between the basis weight of the nonwoven fabric, the heat seal tensile strength, and the elongation. The heat seal tensile strength and heat seal elongation are determined by the following methods. That is, 10 specimens having a width of 5 cm and a length of 31 cm are collected in the longitudinal direction (length direction) of the nonwoven fabric. The sample was cut at 15.5 cm, which is the middle point in the length direction of the obtained sample, the two divided samples were overlapped at a margin of 0.5 cm, and the melting point of the resin constituting the nonwoven fabric was determined by a heat sealer. At a temperature lower by 15 ° C., heat seal adhesion was performed for 0.5 cm width for 3 seconds to obtain a heat seal test piece having a width of 5 cm × length of 30 cm. The obtained heat seal test piece is subjected to a tensile test at a holding interval of 20 cm and a tensile speed of 10 ± 1 cm / min using a constant speed extension type tensile tester, and the strength (N) at the maximum load until breaking is determined. Obtained to the order of 0.1 N, this is the heat seal tensile strength (N / 5 cm). Further, the elongation (cm) at the maximum load is obtained to the order of 0.1 cm, this is divided by the test length (20 cm), and the second decimal place is rounded off to obtain the heat seal elongation (%). The average value of ten points of the obtained tensile strength and elongation is obtained by rounding off the first decimal place, and this is defined as the heat seal tensile strength and elongation of the nonwoven fabric. The basis weight is obtained by the above-described method. Here, the heat seal strength / elongation product per basis weight is obtained by dividing the product of the heat seal tensile strength and heat seal elongation by the basis weight and rounding off the first decimal place.

  In the present invention, the thermoplastic filament constituting the thermoplastic filament nonwoven fabric preferably contains 0.1 to 5.0 wt% of aliphatic bisamide and / or alkyl-substituted aliphatic monoamide. By containing 0.1 wt% or more of aliphatic bisamide and / or alkyl-substituted aliphatic monoamide, the frictional resistance of the filament surface is preferably reduced, and by setting the content to 5.0 wt% or less, It is preferable because deterioration of spinnability is unlikely to occur. A more preferable content range is 0.3 to 4.0 wt%, and a most preferable range is 0.5 to 2.0 wt%. In the present invention, aliphatic bisamides or alkyl-substituted aliphatic monoamides may be used singly or in combination.

The aliphatic bisamide used in the present invention is not particularly limited, and examples thereof include saturated fatty acid bisamides, unsaturated fatty acid bisamides, and aromatic fatty acid bisamides, such as methylene bis stearamide, ethylene bis stearamide, Examples thereof include ethylene bisvalmitic acid amide and ethylene bisoleic acid amide, and a plurality of these may be used in combination.
Examples of the alkyl-substituted aliphatic monoamide used in the present invention include compounds having a structure in which an amide hydrogen such as a saturated fatty acid monoamide or an unsaturated fatty acid monoamide is substituted with an alkyl group, and N-lauryl lauric acid amide and N-palmityl Examples thereof include palmitic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, and a plurality of these may be used in combination.

  In order to contain the aliphatic bisamide and / or the alkyl-substituted aliphatic monoamide in the thermoplastic filament, there are methods such as applying to the surface of the thermoplastic filament, but a method of adding to the blend polymer as a raw material is preferable. The method of adding the aliphatic bisamide and / or the alkyl-substituted aliphatic monoamide to the blend polymer as a raw material for spinning is not limited at all, but the raw resin and the substance to be added are previously heated and melt mixed. The most preferable method is to prepare a master chip and add the necessary amount to the raw material resin during spinning to adjust the amount of the added substance.

  The thermoplastic filament nonwoven fabric used as a nonwoven fabric for tea bags in the present invention is a long-fiber nonwoven fabric composed of continuous filaments, and is obtained by a spunbond method from the viewpoint of high production efficiency and excellent mechanical strength and dimensional stability. Long fiber nonwoven fabric is most preferred. The spunbond method of the present invention is to extrude a melted raw material polymer from a nozzle, suck and stretch it with a high-speed suction gas to form a filament, charge and open it, and deposit and collect it on a moving conveyor to form a fiber web. In this method, the fiber web is integrated into a sheet by heat bonding. In the present invention, the temperature at which the raw polymer is melted is preferably 30 to 90 ° C higher than the melting point of the aliphatic polyester, more preferably 40 to 80 ° C, and most preferably 50 to 70 ° C. When the difference between the melting temperature and the melting point of the aliphatic polyester is less than 30 ° C., the melt viscosity of the raw material becomes too high, and the spinnability tends to become unstable, which is an undesirable direction. When the difference between the melting temperature and the melting point of the aliphatic polyester exceeds 90 ° C., the thermal decomposition of the aliphatic polyester tends to be particularly severe, which is not preferable. Furthermore, the spinning speed at which the filament is drawn by suction is preferably 1500 to 6000 m / min. When the spinning speed is less than 1500 m / min, the filament strength may be insufficient due to insufficient stretching, which is not preferable. When the spinning speed exceeds 6000 m / min, the spinning stability tends to deteriorate, which is not preferable. A more preferable spinning speed range is 2000 to 5000 m / min.

  As a method for integrating the fiber web, thermal bonding is preferable. However, the integration by thermal bonding in the present invention is a method in which fibers are thermally bonded to each other at a contact point, or the thermal bonding is a nonwoven fabric. What is made partially in the range of 5 to 50% with respect to the total area is preferable. As a method of thermally bonding the fibers to each other at the contact point, a heat treatment with a pair of flat rolls or a process of blowing hot air (air through bonding process) is preferable. Further, as a method of partially thermally bonding, a heat embossing process using a pair of embossing rolls or a heat embossing process using an embossing roll and a flat roll is preferable. In the partial thermal bonding, when the ratio of the bonding area is less than 5% with respect to the total area of the nonwoven fabric, the strength of the nonwoven fabric tends to be insufficient, which is not preferable. When the ratio of partial thermal bonding exceeds 50% with respect to the total area of the nonwoven fabric, the texture of the nonwoven fabric tends to be too hard, and further, when the tea bag is immersed in warm water, the extraction speed becomes slow. The taste of tea extracted by the above becomes unpreferable. A more preferable ratio of partial thermal bonding is 8 to 30%. Furthermore, the temperature of these thermal bonding is preferably 5 to 70 ° C., more preferably 10 to 60 ° C. lower than the melting point of the aliphatic polyester constituting the filament. When the temperature difference between the thermal bonding temperature and the melting point of the aliphatic polyester is less than 5 ° C., the thermal bonding tends to be too strong, which is not preferable. When the temperature exceeds 70 ° C., thermal bonding may be insufficient, which is an undesirable direction.

  The extract to be filled in the tea bag made of the nonwoven fabric of the present invention is generally, for example, black tea, green tea or oolong tea as tea leaves, but is not limited thereto, hoji tea, sencha, barley tea, medicinal herbs. Etc.

The shape of the tea bag made of the nonwoven fabric of the present invention may be a flat bag, but if it is a three-dimensional shape, there is a space, and when the tea bag is placed in hot water, the volume of the tea bag is large. It is preferable because leaf swelling and spreading are good and extraction is performed quickly.
As a three-dimensional shape, for example, a tetrahedral shape such as a triangular pyramid three-dimensional shape or a tetrapack shape can be cited as a preferable example.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto. Moreover, the evaluation method used in the Example and its measurement conditions are demonstrated below.

(1) Polymer melt viscosity (poise)
The melt viscosity of the polymer was measured with a capillarograph 1B manufactured by Toyo Seiki Seisakusho. The polymer storage time from sample introduction to measurement start was 10 minutes.

(2) Melting point (° C)
Using a Perkin Elmer DSC-7, the peak top temperature indicating the melting of the polymer at 2nd run was taken as the melting point of the polymer. The temperature rising rate at this time was 20 ° C./min, and the sample amount was 10 mg.

(3) Weight average molecular weight The weight average molecular weight of polylactic acid was calculated | required with the following method. Tetrahydrofuran was mixed with the chloroform solution of the sample to obtain a measurement solution, which was measured at 25 ° C. using a gel permeation chromatograph (GPC) Waters 2690 manufactured by Waters, and the weight average molecular weight was determined in terms of polystyrene. Three measurements were performed for each sample, the average value was calculated, and the weight average molecular weight was rounded off to the nearest thousand.

(4) Single fiber fineness (decitex):
Ten small sample samples are taken at random from the nonwoven fabric, photographed at 500 to 3000 times with a scanning electron microscope or the like, 10 from each sample, the diameter of 100 fibers in total, and the average value thereof. The fiber diameter calculated by rounding off the 0.01 μm position was corrected by the polymer density, and the first decimal place was rounded off.

(5) Weight per unit area (g / m ² ):
Three samples each having a size of 50 cm in length and 50 cm in width were collected from the nonwoven fabric, and each weight was measured. The average value of the obtained values was converted per unit area, and the first decimal place was rounded off.

(6) Dispersion state of polyamide component (average single fiber fineness: decitex)
Ten small piece samples are randomly collected from the nonwoven fabric, embedded in an epoxy resin, cut in the cross-sectional direction, cut into ultrathin sections, and cut into 40,000 to 100,000 with a transmission electron microscope (TEM: H7100FA type manufactured by Hitachi). Photos were taken at double magnification. Measure the cross-sectional area of the polyamide component from each sample, 20 in total, 200 in total, calculate the average value thereof, convert this to the fiber diameter of the circular fiber, and correct it with the polymer density to obtain the polyamide component The single fiber fineness was determined. In TEM observation, when it was difficult to distinguish between polyamide and aliphatic polyester, the sample was appropriately stained.

(7) Thermal shrinkage (%)
Referring to JIS L1906 (2000 edition) 5.9.1 and 5.9.2, 10 samples of 25 cm long x 25 cm wide were taken from any part of the non-woven fabric, and 20 cm in each of the vertical and horizontal positions were 20 cm. Mark the length (measured to the nearest 0.01 cm) and immerse in boiling water for 5 minutes in a suitable container. Remove the test piece, drain lightly with a filter paper, etc., and remove the unnatural wrinkle without twisting or stretching, and let it dry on a flat screen with a horizontal screen mesh or similar hole. For 10 samples, measure the length of 3 marked vertical and horizontal directions to 0.01 cm units, apply the total of 10 samples to the following formula, and round off the first decimal place. Calculate heat shrinkage.

Thermal contraction rate (%) = ((L1-L2) / L1) × 100
Here, L1: Total length of three wires before heating (total of 10 samples) (cm)
L2: Total length of three wires after heating (total of 10 samples) (cm).

(8) Ten test specimens having a width of 5 cm and a length of 31 cm are collected in the longitudinal direction (length direction) of the heat-sealable high-stretch product nonwoven fabric per unit weight. The sample was cut at 15.5 cm which is the middle point in the length direction of the obtained sample, the two divided samples were overlapped at a margin of 0.5 cm, and 160 ° C., 0.5 cm width, Heat seal adhesion was performed for 3 seconds to obtain a heat seal test piece having a width of 5 cm and a length of 30 cm. The obtained heat seal test piece is subjected to a tensile test at a holding interval of 20 cm and a tensile speed of 10 ± 1 cm / min using a constant speed extension type tensile tester, and the strength (N) at the maximum load until breaking is determined. Obtained to the order of 0.1 N, this is the heat seal tensile strength (N / 5 cm). Further, the elongation (cm) at the maximum load is obtained to the order of 0.1 cm, this is divided by the test length (20 cm), and the second decimal place is rounded off to obtain the heat seal elongation (%). The average value of ten points of the obtained tensile strength and elongation is obtained by rounding off the first decimal place, and this is defined as the heat seal tensile strength and elongation of the nonwoven fabric. The basis weight is obtained by the above-described method. Here, the heat seal strength / elongation product per unit weight is obtained by dividing the product of the heat seal tensile strength and the heat seal elongation by the basis weight obtained by the method of (5) above, and calculating the first decimal place. It is calculated by rounding off.

Example 1
Melt viscosity 570 poise (240 ° C., shear rate 2432 sec ⁻¹ ), melting point 220 ° C. nylon 6 (40 wt%), weight average molecular weight 120,000, melt viscosity 300 poise (240 ° C., shear rate 2432 sec ⁻¹ ), melting point 170 ° C. Of poly (L-lactic acid) (optical purity 99.5% or more) (60 wt%) was kneaded at 240 ° C. with a twin screw extruder kneader to obtain a blend polymer chip.

Using this blend polymer chip as a raw material, the raw material is melted by an extruder at 240 ° C., spun from a round pore at a spinning temperature of 240 ° C., and then spun at a spinning speed of 4200 m / min by a ejector. Using a embossing roll and a flat roll, the roll temperature is 140 ° C., the linear pressure is applied to the web obtained by opening the yarn with a fiber device and collecting it on the moving conveyor. thermally bonded under conditions of 50 kg / cm, to obtain a single fiber fineness 2 dtex, basis weight 150 g / ^{m 2} nonwoven fabric.

(Example 2)
The nonwoven fabric was manufactured under the same conditions as in Example 1 except that the discharge amount and the moving speed of the net conveyor were adjusted so that the single fiber fineness was 1.8 dtex and the basis weight was 30 g / m ² .

(Example 3)
To the blend polymer chip used in Example 1, 0.5 wt% of ethylenebisstearic acid amide was added, melted in an extruder at 240 ° C., spun from a round pore at a spinning temperature of 240 ° C., and then ejector An embossing roll that spins at a spinning speed of 4000 m / min, opens the yarn with a known opening device, and collects the web collected on the moving conveyor with a crimping area ratio of 16%. And a flat roll, and heat bonded under the conditions of a roll temperature of 140 ° C. and a linear pressure of 50 kg / cm, to obtain a nonwoven fabric having a single fiber fineness of 1.8 dtex and a basis weight of 50 g / m ² .

Example 4
Under the same conditions as in Example 1, only the weight ratio of nylon 6: poly (L-lactic acid) was changed to 20:80 to obtain a blend chip. To this blend polymer chip, 0.5% by weight of ethylenebisstearic acid amide was added, the raw material was melted at 240 ° C with an extruder, spun from a round pore at a spinning temperature of 245 ° C, and then spun with an ejector. An embossing roll and a flat roll that are spun at a speed of 3900 m / min, opened the yarn with a known opening device, and collected on the moving conveyor, with a crimping area ratio of 13% Was used for heat bonding under the conditions of a roll temperature of 140 ° C. and a linear pressure of 50 kg / cm to obtain a nonwoven fabric having a single fiber fineness of 2 dtex and a basis weight of 30 g / m ² .

(Example 5)
To the blend polymer chip used in Example 1, 0.5 wt% of ethylenebisstearic acid amide was added, and further 1 wt% of TIC was added with respect to the content of poly (L-lactic acid). After melting and spinning from round pores at a spinning temperature of 245 ° C., spinning at a spinning speed of 3500 m / min with an ejector, opening the yarn with a known opening device, and collecting on a moving conveyor The resulting web was thermally bonded using an embossing roll and a flat roll with a crimp area ratio of 16% under the conditions of a roll temperature of 135 ° C. and a linear pressure of 50 kg / cm, and the single fiber fineness was 2 dtex and the basis weight. A nonwoven fabric of 50 g / m ² was obtained.

  The properties of the obtained nonwoven fabric are as shown in Table 1, but the nonwoven fabrics of Examples 1 to 5 are all heat-sealed despite containing poly (L-lactic acid) resin which is an aliphatic polyester. The tensile strength and elongation were high, and the nonwoven fabrics of Examples 2 to 5 had excellent heat seal strength / elongation products per unit weight of 85, 98, 93, and 109, respectively.

(Comparative Example 1)
Using the poly (L-lactic acid) resin described in Example 1 as a raw material, the raw material was melted with an extruder at 230 ° C., spun from a round pore at a spinning temperature of 235 ° C., and then a spinning speed of 4400 m / second with an ejector. The web obtained by spinning in min, opening the yarn with a known opening device, and collecting it on the moving conveyor, using an embossing roll and a flat roll with a crimping area ratio of 16% Then, heat bonding was performed under the conditions of a roll temperature of 140 ° C. and a linear pressure of 50 kg / cm to obtain a nonwoven fabric having a single fiber fineness of 2 dtex and a basis weight of 50 g / m ² .

Claims (3)

A non-woven fabric for tea bags made of a thermoplastic filament nonwoven fabric, wherein the thermoplastic filament is a blend polymer of polylactic acid and nylon 6 ,
The thermoplastic filament nonwoven fabric has both a vertical and horizontal heat shrinkage of -5 to + 10% after being immersed in boiling water for 5 minutes,
The single filament fineness of the thermoplastic filament is 1 to 15 dtex, the basis weight of the nonwoven fabric is 10 to 100 g / m ² , and the heat seal strength / elongation product per basis weight is 80 to 200,
The blend polymer of polylactic acid: the weight ratio of nylon 6 50:50 to 85:15,
A long-fiber non-woven fabric for tea bags, wherein nylon 6 component is finely dispersed with an average single fiber fineness of 1 × 10 ⁻⁷ to 1 × 10 ⁻³ dtex in the cross-sectional direction of the thermoplastic filament. The long-fiber nonwoven fabric for tea bags according to claim 1 , wherein the fibers constituting the nonwoven fabric are heat-bonded to each other. Tea bag made of long-fiber nonwoven fabric according to claim 1 or 2.