JP4294814B2 - Polylactic acid flat yarn - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is composed of a thermoplastic polymer mainly composed of a biodegradable lactic acid-based polymer, and can be continuously woven by a current loom, maintains excellent strength even after long-term use, and is promptly disposed of after disposal. It is related to flat yarn that is decomposed into, and does not accumulate in the natural environment.
[0002]
[Prior art]
Conventionally, sandbags and flexible container bags containing waste materials used on the shore or riverside have been made of materials such as polyethylene and polypropylene for a long time. Soil bags and flexible container bags made of these materials are used in large quantities because they have excellent mechanical properties and are very inexpensive. However, once the mission is finished and disposed of, the contents must be separated. There was a problem that it had to be troublesome and costly.
In order to solve these problems, Japanese Patent No. 2808192 exemplifies a sandbag using a biodegradable plastic. However, since the biodegradable plastic of the above-mentioned patent is a plastic made of polyester produced by microorganisms, the degradation rate is fast, the period of use is as short as 6 weeks or less, and it can sufficiently withstand use in a short period of time. However, it was unsuitable for sandbags that were used for some time.
In recent years, flat yarns have been obtained by extrusion molding using a microbial degradable aliphatic polyester, and attempts have been made to produce biodegradable sandbags and flexible container bags through a bag making process. It has low tensile strength and knot strength, has a lot of cutting at the time of bag making, has a very high production loss, and is suitable for short- and medium-term use because it is a microorganism-degradable type, but not suitable for long-term use. There was a problem.
[0003]
[Problems to be solved by the invention]
An object of the present invention is to provide a flat yarn having biodegradability, capable of continuous weaving with an existing loom, and having excellent strength even after long-term use.
[0004]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have found that a flat yarn obtained by slitting a uniaxially stretched film having a specific birefringence and having a main component of polylactic acid is a conventional loom. Thus, the inventors have found that it is possible to stably weave, and have reached the present invention.
That is, the present invention is a flat yarn using a monoaxially stretched film mainly composed of polylactic acid containing a lubricant, and the flat yarn is a biodegradable aliphatic polyester that is substantially incompatible with polylactic acid. the containing 5 to 20 wt%, a relative viscosity of the flat yarn is 1.8 or more, soil degradable polylactic acid flat yarn, wherein the birefringence is 0.035 or less.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
The flat yarn of the present invention is mainly composed of polylactic acid containing a lubricant. The constituent ratio of polylactic acid is preferably 75% by weight or more. When the polylactic acid component is less than 75% by weight, the strength required for the flat yarn is lowered.
Polylactic acid includes poly-L-lactic acid in which the structural unit of lactic acid is L-lactic acid, poly-D-lactic acid in which the structural unit is D-lactic acid, and poly-DL-in which is a copolymer of L-lactic acid and D-lactic acid. Lactic acid or a mixture thereof, and the number average molecular weight is 90,000 to 110,000.
The polylactic acid may contain a small amount of a copolymer component within the scope of the present invention. Examples of the copolymer component include 5-sodium sulfoisophthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, and the like. Aromatic dicarboxylic acid component, aliphatic dicarboxylic acid component such as adipic acid, sebacic acid, ethylene glycol, diethylene glycol, butylene glycol, 1,4-cyclohexanedimethanol, alkylene oxide addition product of bisphenol A, alkylene oxide addition of bisphenol S Glycol components such as products, and hydroxycarboxylic acid components such as 4-hydroxybenzoic acid and ε-caprolactone.
[0006]
In the present invention, the flat yarn needs to contain a lubricant. In other words, the polyaxially uniaxially stretched film is inferior in slipperiness as it is, and the vertical crack (fibrillation) is severe, and the flat yarn is not smoothly fed in the loom, which deteriorates the operability during the weaving process. Therefore, a lubricant is added to improve the slipperiness of the flat yarn and prevent fibrillation.
The lubricant is not particularly limited, and examples thereof include inorganic lubricants such as silica, talc, and calcium carbonate, liquid paraffin, microcrystalline wax, natural paraffin, synthetic paraffin, aliphatic hydrocarbon lubricants such as polyethylene, stearic acid, and lauryl. Fatty acid lubricants such as acid, hydroxystearic acid, hydrogenated castor oil, stearic acid amide, oleic acid amide, erucic acid amide, lauric acid amide, ethylene bisstearic acid amide, ethylene bis oleic acid amide, ethylene bis lauric acid amide Amide lubricant, aluminum stearate, lead stearate, calcium stearate, magnesium stearate, etc., metal soap lubricant, glycerin fatty acid ester, sorbitan fat Fatty acid (partial) ester-based lubricants of polyhydric alcohols such as acid esters, fatty acid ester-based lubricants such as long-chain ester waxes such as butyl stearate and montan wax, or composite lubricants in which these are combined, especially inorganic A combination of a lubricant and an organic lubricant is preferable, and specifically, a combination of silica and erucic acid amide or silica, erucic acid amide and aluminum stearate is preferable.
[0007]
Lubricant can be added by a masterbatch method or a direct addition method, or previously dispersed in a biodegradable aliphatic polyester substantially incompatible with polylactic acid and added to polylactic acid. These methods can also be used in combination. In particular, when a lubricant is added using both of these methods, in addition to the sliding effect provided by the lubricant dispersed in the polylactic acid matrix, the lubricant in the incompatible resin microdispersed in the polylactic acid further slips. It is preferable for improving the property. Further, the master batch or a lubricant directly added to polylactic acid and the lubricant dispersed in the biodegradable aliphatic polyester substantially incompatible with polylactic acid may be the same or different.
The amount of the lubricant added is preferably 0.5 to 5% by weight of the flat yarn, including the amount of lubricant contained in the biodegradable aliphatic polyester substantially incompatible with polylactic acid. If the amount of lubricant added is less than 0.5% by weight, there is substantially no effect, and if it exceeds 5% by weight, production troubles such as an increase in pack pressure during film formation are not preferred.
[0008]
In the present invention, it is necessary to blend a biodegradable aliphatic polyester that is substantially incompatible with polylactic acid in order to prevent fibrillation and to impart viscosity to the film and flat yarn.
Specific examples of biodegradable polyesters that are substantially incompatible with polylactic acid include aliphatic polyesters obtained by condensing aliphatic diols and aliphatic dicarboxylic acids, and aliphatic polyesters obtained by ring-opening polymerization of cyclic lactones. And synthetic aliphatic polyesters.
An aliphatic polyester obtained by condensing an aliphatic diol and an aliphatic dicarboxylic acid is an aliphatic dicarboxylic acid such as ethylene glycol, 1,4-butanediol, and 1,4-cyclohexanedimethanol, which are aliphatic diols. One or more kinds each selected from succinic acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid and the like are obtained by condensation polymerization.
If necessary, a desired polymer can be obtained by jumping up with an isocyanate compound or the like.
Typical examples of the aliphatic polyester obtained by ring-opening polymerization of cyclic lactones include cyclic monomers such as ε-caprolactone, δ-valerolactone, and β-methyl-δ-valerolactone. Polymerized.
Synthetic aliphatic polyesters include cyclic acid anhydrides and oxiranes, such as copolymers of succinic anhydride with ethylene oxide, propylene oxide, and the like.
Particularly preferably used as the biodegradable aliphatic polyester is an aliphatic polyester obtained by condensing an aliphatic diol and an aliphatic dicarboxylic acid, and specific examples thereof include polyethylene adipate, polypropylene adipate, polybutylene adipate, Examples include polyhexyl adipate, polybutylene succinate, polybutylene succinate adipate, and the like.
[0009]
By blending a biodegradable aliphatic polyester that is substantially incompatible with polylactic acid, the flat yarn is moist and sticky, improving convergence, making fibrillation difficult, and flat yarn nodules. There is also an effect of improving strength. The blending amount of the biodegradable aliphatic polyester is required to be 5 to 20% by weight of the flat yarn. When the blending amount of the biodegradable aliphatic polyester is less than 5% by weight, the resulting flat yarn cannot be given a moist feeling and convergence, and fibrillation becomes intense. On the other hand, if it exceeds 20% by weight, good mechanical properties of polylactic acid are impaired.
[0010]
In the polylactic acid-based flat yarn of the present invention, functionalities such as an anti-blocking agent and antistatic, flame retardant, light resistance, antifouling, ultraviolet protection, plasticizer, etc., in addition to the lubricant, are within the range not impairing the object of the present invention. Additives, matting agents, pigments, and the like for the purpose of imparting water may be blended.
[0011]
The relative viscosity of the flat yarn of the present invention needs to be at least 1.8 or more, preferably 1.95 or more. The relative viscosity here is measured under the conditions of a temperature of 20 ° C. and a concentration of 0.5 g / dl using a mixed solvent of phenol / 1,1,2,2-tetrachloroethane (weight ratio 1/1) as a solvent. Refers to solution viscosity. When the relative viscosity of the flat yarn is less than 1.8, the flat yarn has a low tensile strength and is not preferable because it is cut during weaving.
[0012]
An important property in the flat yarn of the present invention is the birefringence of the film. The birefringence needs to be 0.035 or less, preferably 0.033 or less. The birefringence here is measured by a retardation method using a polarizing microscope. When the birefringence exceeds 0.035, since the orientation is advanced, the flat yarn is rubbed at the time of winding with a paper tube by traverse, causing vertical cracks (fibrillation), and cutting due to fibrillation in the weaving process. This is not preferable because the operability is significantly deteriorated.
[0013]
The flat yarn of the present invention preferably has a fineness of 500 to 6000 dtex, a tensile strength of 2.2 cN / dtex or more, and a knot strength of 2.2 cN / dtex or more.
If the fineness of the flat yarn is less than 500 dtex, the absolute strength will be insufficient, the flat yarn will be torn during the weaving process on the loom, and even if a bag can be made, its strength as a bag will be low, and it will break during operation. Since there is a possibility of bagging, it is not preferable. On the other hand, if it exceeds 6000 dtex, weaving may not be possible because it does not meet the specifications of the loom. Further, when the knot strength is less than 2.2 cN / dtex, the flat yarn is cut in the weaving process on the loom.
The thickness and width of the film are not particularly limited, but may be designed to fall within the fineness range in consideration of workability when weaving and necessary strength.
[0014]
As a method for forming a polylactic acid film used as a material for the polylactic acid flat yarn of the present invention, for example, a melt casting method, a melt extrusion method, a calendering method or the like can be used. The melt extrusion method is generally used.
As the melt extrusion method, a known T-die method, inflation method or the like can be applied. The extrusion temperature is in the range of 170-250 ° C, preferably 190-230 ° C. If the molding temperature is too low, the film forming becomes unstable, and if it is too high, polylactic acid is decomposed, resulting in problems such as reduction in the strength of the resulting film or coloring.
The polylactic acid film in the present invention needs to be uniaxially stretched. In the flat yarn obtained from the biaxially stretched film, since the molecules are oriented vertically and horizontally, if any crack exists in the transverse direction, it is not preferred because it easily cuts and leads to frequent cutting during the weaving process. In the case of uniaxial stretching, it is preferably stretched 4 to 8 times in the longitudinal direction. If the draw ratio is too low, it will not only produce stretch spots, but it will be difficult to obtain a film with a sufficiently satisfactory strength. If it is too high, the molecular orientation will be high and birefringence will be high, and vertical cracking (fibrillation) will occur. ) Occurs frequently, which is not preferable.
The stretching temperature is preferably in the range of not less than the glass transition temperature (Tg) and not more than (Tg + 65) ° C. of the polylactic acid used. If the stretching temperature is less than Tg, stretching is difficult, and if it exceeds (Tg + 65) ° C., strength improvement due to stretching may not be observed. In order to increase heat resistance and dimensional stability, heat treatment may be performed after stretching at a temperature of 70 ° C. or higher and lower than the melting point under tension.
The flat yarn of the present invention can be woven with an existing loom and easily processed into a sandbag or a flexible container bag. Also, sandbag bags and flexible container bags made of these flat yarns can withstand long-term use, and after completing their roles, for example, use steam to create a high-temperature and high-humidity environment; Can promote degradation and will not accumulate in the natural environment after disposal.
[0015]
【Example】
Next, the present invention will be described more specifically with reference to examples.
In addition, the measuring method of each physical-property value used in the Example and the comparative example is as follows.
(1) Tensile strength and knot strength of flat yarn: measured according to JIS Z 1533.
(2) Tensile strength of woven fabric: measured according to JIS Z 1096.
[0016]
Example 1
Polybutylene succinate adipate containing 5% by weight of silica and erucamide for 90% by weight of polylactic acid (Cargoill Dow Polymers, ECOPLA) with a number average molecular weight of 100,000 and D% of 1 mol% Using an extruder equipped with a round die at 200 ° C., 10% by weight (produced by Showa Polymer Co., Ltd., Bionore) was mixed with 10% by weight (hereinafter, Bionore containing a lubricant is abbreviated as Bionore Master). It was melt-kneaded and extruded by an inflation method to obtain an unstretched film. After slitting this unstretched film, it was heated to 120 ° C. and uniaxially stretched seven times in the length direction by a roll method to obtain flat yarns of 1100 dtex and 3300 dtex. Table 1 shows various physical property values of these flat yarns.
Next, a 1100 dtex flat yarn was woven with a water jet loom and a 3300 dtex one with a sulzer loom to obtain a plain weave fabric. The physical property values of the obtained woven fabric are shown in Table 1.
[0017]
Reference Example Polylactic acid (number average molecular weight 100,000, D% is 1 mol%) containing 10% by weight of erucic acid amide with respect to 80% by weight of polylactic acid used in Example 1 (abbreviated as erucic acid amide master) A flat yarn and a woven fabric were obtained in the same manner as in Example 1 except that 20% by weight of the chip was mixed. These various physical property values are shown in Table 1.
[0018]
Example 2
A flat yarn and a woven fabric were prepared in the same manner as in Example 1 except that 85% by weight of polylactic acid used in Example 1 was mixed with 10% by weight of Bionore Master and 5% by weight of Erucamide Master. Obtained. These various physical property values are shown in Table 1.
[0019]
Comparative Example 1
A flat yarn and a woven fabric were obtained in the same manner as in Example 1 except that the draw ratio was increased to 4.3 times without adding a lubricant. These various physical property values are shown in Table 1.
[0020]
Comparative Example 2
A flat yarn and a woven fabric were obtained in the same manner as in Example 1 except that polylactic acid having a number average molecular weight of 30,000 and D% of 1 mol% (ECOPLA manufactured by Cargill Dow Polymers) was used. These various physical property values are shown in Table 1.
[0021]
Comparative Example 3
A flat yarn was obtained in the same manner as in Example 1 except that the draw ratio was changed to 10. Table 1 shows various physical property values of these flat yarns.
[0022]
Comparative Example 4
A 1100 decitex flat yarn and woven fabric were obtained in the same manner as in Example 1 except that polybutylene succinate (manufactured by Showa High Polymer Co., Ltd., Bionore) was used instead of polylactic acid and the draw ratio was increased to 4. . These various physical property values are shown in Table 1.
[0023]
In Examples 1 and 2 and Reference Example , a flat yarn having excellent tensile strength and knot strength and no fibrillation was obtained, and a woven fabric having excellent tensile strength was obtained. In addition, weaving was possible without any trouble in the weaving process. There was no decrease in strength even after 6 months of leaving the riverbank, and long-term use was possible.
In Comparative Example 1, since the polylactic acid was not blended with a lubricant, the smoothness was poor, and the draw ratio could only be set up to 4.3 times by winding around a roll or whitening. Therefore, the flat yarn obtained had low tensile strength and knot strength. Moreover, since the slipperiness was also poor, cutting troubles frequently occurred in the weaving process, and the strength of the obtained woven fabric was low.
In Comparative Example 2, since the polylactic acid used had a low molecular weight, the resulting flat yarn also had a low relative viscosity, and therefore had a low tensile strength and knot strength. For this reason, the obtained woven fabric was also low in strength. Moreover, since the knot strength of the flat yarn was low, it could not withstand the mechanical weaving and the cutting occurred frequently. The strength after 6 months of leaving the riverbank was slightly reduced, but it was not a problem.
In Comparative Example 3, since the draw ratio was 10 times, the obtained flat yarn was fibrillated vigorously, so that the tensile strength and knot strength were low, and mechanical weaving with a loom could not be performed.
In Comparative Example 4, the resin used was Bionore, which is a biodegradable aliphatic polyester. Therefore, when the film was stretched 7 times as in Example 1, the whitening was severe and the film could only be stretched up to 4 times. For this reason, the nodule strength was low. In addition, the drop in strength after 6 months of standing on the riverbank was so severe that it could not withstand long-term use.
[0024]
[Table 1]
[0025]
【The invention's effect】
According to the present invention, a flat yarn obtained by slitting a uniaxially stretched film mainly containing polylactic acid and having a relative viscosity of 1.8 or more and birefringence of 0.035 or less, according to the present invention, It is excellent in strength, and the slipperiness is remarkably improved, so that weaving by mechanical weaving is easy and it has soil degradability. In addition, by blending a biodegradable aliphatic polyester that is substantially incompatible with polylactic acid, the flat yarn is moist and sticky, improves convergence, makes fibrillation difficult, and flat yarn. There is also an effect of improving the nodule strength. Such flat yarns are suitable for applications such as sandbags and flexible containers.

Claims (2)

A flat yarn using a uniaxially stretched film mainly composed of polylactic acid containing a lubricant, wherein the flat yarn contains 5 to 20% by weight of a biodegradable aliphatic polyester substantially incompatible with polylactic acid. containing, and the relative viscosity of the flat yarn is 1.8 or more, soil degradable polylactic acid flat yarn, wherein the birefringence is 0.035 or less. The stretching ratio of the uniaxially stretched film is 4 to 8 times, the fineness of the flat yarn is 500 to 6000 dtex, the tensile strength is 2.2 cN / dtex or more, and the knot strength is 2.2 cN / dtex or more. 2. The polylactic acid-based flat yarn according to claim 1, wherein