JP5082925B2 - Resin composition - Google Patents

Description

  The present invention relates to a resin composition containing polyamide, polylactic acid, and a decomposition inhibitor, wherein the generation of decomposition gas during melt molding is suppressed.

  Fibers made of polyamides typified by nylon 6 and nylon 66, and fibers made of polyesters typified by polyethylene terephthalate, polybutylene terephthalate and polylactic acid are excellent in strength, mechanical properties and dimensional stability. Widely used in interiors, vehicle interiors, and industrial applications. In addition, fibers made of polyolefins such as polyethylene and polypropylene are widely used for industrial applications taking advantage of their lightness.

  However, even in the above-mentioned fibers, the performance of a fiber made of a single resin (polymer) is limited. Therefore, it is possible to combine functions by compounding, copolymerization with other components, or two or more types of resins (polymers). Modification of resins by polymer blends, etc., in which) is mixed has been studied. In particular, polymer blends do not require a new resin composition design, and high-performance products can be manufactured using a single-component melt molding machine. ing.

  As an example of such a polymer blend fiber, a polymer blend fiber of polyamide and polyester has been proposed (see Patent Document 1). Here, polyester is dissolved and removed from a polymer blend fiber of polyamide and polyester to obtain ultrafine fibers made of polyamide, but polylactic acid used as polyester is highly hydrolyzable, so polyamide is efficiently used. Ultrafine fibers can be obtained, and polylactic acid and polyamide can be said to be an effective combination.

  However, in this polymer blend, nylon 6, which is a high melting point polyamide, is melted, so that it is necessary to set the melting temperature to a higher temperature than in the case of polylactic acid alone, and the melt viscosity is lowered due to thermal degradation of the polymer. There was a problem of accompanying drip, deterioration of color tone of the obtained product, and deterioration of mechanical properties. In particular, in the case of melt spinning, since the polymer is discharged through a complicated and complicated spinning pipe in the spinning machine, the polymer is exposed to a high temperature for a long time, and thermal deterioration is particularly serious. Therefore, it has been desired to improve the heat resistance of a resin composition containing polyamide and polylactic acid. As a technology for improving the heat resistance of a resin composition containing polyamide and polylactic acid, by adding a phosphorus compound or a hindered phenol compound to the resin composition, characteristics such as melt viscosity retention, color tone improvement or molecular weight retention can be obtained. It has been proposed that it can be improved (see Patent Document 2 and Patent Document 3). On the other hand, proposals have also been made to improve the heat resistance of polylactic acid itself. Specifically, a technique using a phosphate compound and a phenol compound in combination (see Patent Document 4), or a technique adding a phenol compound ( Patent Document 5) has been proposed.

  With the above-described technique, it was possible to improve molecular weight, melt viscosity, color tone, and the like to some extent. However, as a result of further investigation, it was found that polymer blends composed of polyamide and polylactic acid have a problem that a large amount of decomposition gas is likely to be generated due to thermal decomposition of the polymer, compared to the case of polyamide alone or polylactic acid alone. It was.

  The cracked gas generated at this time contains lower fatty acids, ε-caprolactam, and the like, and this cracked gas is generated at the time of melt molding, which not only deteriorates the environment at the manufacturing site, but also contains metal in the cracked gas. Since it contains components such as lower fatty acids that have corrosive properties, corroding the piping and measuring section of the melt molding equipment, in addition to deterioration of quality due to foreign matter mixing and deterioration of quality stability due to reduced discharge lightness If the continuous production is continued, it may cause serious problems such as breakage of parts of the melt molding apparatus.

Therefore, in the polymer blend of polyamide and polylactic acid, a technology for suppressing the generation of cracked gas containing this lower fatty acid and ε-caprolactam was necessary, but the conventional technology is insufficient to suppress the generation of cracked gas. Met. For example, when the additive recommended in Patent Document 2 is used, the melt viscosity retention rate is certainly improved, but it has no effect on the suppression of cracked gas. This suggests that the generation of cracked gas may be due to the chemical reaction between polyamide and polylactic acid and the additive, and the molecular design of the cracking inhibitor based on this is necessary. there were.
JP 2004-169261 A JP, 2007-131696, A Claims JP, 2005-2174, A Claims JP, 2007-23081, A Claims Japanese Patent No. 3532850 Patent Claim

  An object of the present invention is to provide a resin composition containing polyamide, polylactic acid, and a decomposition inhibitor whose generation of decomposition gas during melt processing is suppressed.

  In order to solve the above problems, the present invention has the following configuration. That is, the resin composition of the present invention is a resin composition containing polyamide, polylactic acid, and a decomposition inhibitor, and the molecular structure of the decomposition inhibitor includes a phosphorus atom and a hindered phenol structure simultaneously in one molecule. The decomposition inhibitor is added in an amount of 0.01 to 1 mol% with respect to the entire resin composition.

  According to the preferable aspect of the resin composition of this invention, the quantity of polyamide is 10 to 90 weight% with respect to the whole resin composition.

  According to a preferred embodiment of the resin composition of the present invention, polyamide and polylactic acid form a sea-island structure, and the average dispersion diameter of the island components of this sea-island structure is 10 to 1000 nm.

  The resin composition of the present invention can be spun to produce fibers.

  According to the present invention, a resin composition containing polyamide, polylactic acid, and a decomposition inhibitor, wherein the molecular structure of the decomposition inhibitor includes a phosphorus atom and a hindered phenol structure at the same time in one molecule, By using a resin composition in which 0.01 to 1 mol% of the agent is added to the entire resin composition, the generation of decomposition gas generated at the time of melting is greatly suppressed, and there is an odor drifting to the surrounding environment as well as the production site. In addition to improving the production environment by drastically decreasing, corrosion of the piping and measuring section of the melt processing apparatus is suppressed, so that continuous production with stable quality becomes possible.

  The resin composition of the present invention contains polyamide, polylactic acid and a decomposition inhibitor as basic components.

  The polyamide used in the present invention is a resin having an amide bond in the main chain, such as nylon 6, nylon 66, nylon 46, nylon 9, nylon 10, nylon 11, nylon 12 and nylon 612, or the like. Examples thereof include compounds having an amide-forming functional group, such as copolymerized polyamides containing copolymer components such as laurolactam, sebacic acid, terephthalic acid, isophthalic acid and 5-sodium sulfoisophthalic acid. Among these, nylon 6 and nylon 66 are particularly preferably used from the viewpoint of versatility.

  In addition, the polyamide used in the present invention may be end-capped with a carboxylic acid compound or an amine compound as necessary, and the end of the polyamide blocked the autocatalytic function and improves heat resistance. Easy to make. Examples of the carboxylic acid compound used here include aliphatic monocarboxylic acids, alicyclic monocarboxylic acids, aromatic monocarboxylic acids, aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, and aromatic dicarboxylic acids. Examples of the amine compound include aliphatic monoamines, alicyclic monoamines, aromatic monoamines, aliphatic diamines, alicyclic diamines, and aromatic diamines.

  The polylactic acid used in the present invention is a resin mainly composed of L-lactic acid and / or D-lactic acid. However, in order for polylactic acid to have high heat resistance, the optical purity of the lactic acid component as polylactic acid. It is preferable to use one having a high value. Therefore, among the total lactic acid components of polylactic acid, polylactic acid containing 80% or more of L-form or 80% or more of D-form is preferred, and more preferably 90% or more of L-form is contained or D Polylactic acid containing 90% or more of the body, and more preferably polylactic acid containing 95% or more of the L-form or 95% or more of the D-form.

  As a method for producing polylactic acid, known polymerization methods can be used, and examples thereof include a direct polymerization method from lactic acid and a ring-opening polymerization method via lactide.

  The melting point of polylactic acid is preferably 120 ° C. or higher, and more preferably 150 ° C. or higher. The melting point of polylactic acid is usually increased by increasing the optical purity of the lactic acid component, and polylactic acid having a melting point of 120 ° C. or higher contains 90% or more of L-form or 90% or more of D-form. Polylactic acid having a melting point of 150 ° C. or higher can be obtained by containing 95% or more of L-form or 95% or more of D-form.

  The polylactic acid used in the present invention may contain other copolymerization components. Examples of other copolymer components include glycol compounds, dicarboxylic acids, hydroxycarboxylic acids, and lactones. These copolymer components may cause a melting point drop due to copolymerization, and conversely promote decomposition gas generation. However, the copolymerization amount is 0 to 30 mol% with respect to the total monomer components. If there is no problem, it can be used.

  In the resin composition of the present invention, it is important that the above-mentioned polyamide and polylactic acid are added with a decomposition inhibitor having a structure in which the molecular structure includes a phosphorus atom and a hindered phenol structure simultaneously in one molecule. .

  When the polymer is heated and melted, if the heat resistance of the polymer is low, organic radicals may be generated due to thermal decomposition of the polymer and oligomers contained therein. And once an organic radical generate | occur | produces, the peroxide used as a new radical and a radical initiator may be produced | generated in a chain. Since the organic radical has an unstable structure, the polymer is further decomposed and a new organic radical is generated. In this way, once the organic radical is generated, the decomposition of the polymer proceeds in a chain and the molecular weight is lowered, and in some cases, a volatile decomposition gas is generated. Furthermore, when the decomposition product is further oxidized with a peroxide, a corrosive gas such as a lower fatty acid is generated.

  In the case of polymer blends, it is more complicated, and depending on the combination of polymers, it acts as a catalyst at the polymer interface where organic radicals, thermal decomposition products, peroxides, etc. generated from one polymer are blended, and the other polymer decomposes. May be promoted, and decomposition may be promoted more than the case of each polymer alone.

  This is a problem specific to polymer blends. In particular, in the combination of polyamide and polylactic acid targeted by the present invention, as shown in Reference Examples 1 to 3 to be described later, thermal decomposition is easier to proceed than in the case of polyamide or polylactic acid alone, and a large amount of decomposition gas is present. There is a problem that occurs. In fact, in Reference Example 1 which is a polymer blend, ε-caprolactam is generated 5 times or more in terms of the weight of polyamide compared to polyamide alone (Reference Example 2), and polylactic acid compared to polylactic acid alone (Reference Example 3). 4-9 times lower fatty acids are generated in terms of weight, and 2,3-pentanedione, which is hardly generated by each polymer alone, is generated, and the degradation products of polyamide and polylactic acid decompose each other. It is thought that they are in mutual contact. For example, it is considered that lower fatty acid generated from polylactic acid decomposes polyamide to generate ε-caprolactam, which further decomposes polylactic acid (amine decomposition, hydrolysis, etc.) and accelerates decomposition. Thus, especially the combination of polyamide and polylactic acid is not only susceptible to chemical decomposition gas generation because each decomposition product easily promotes decomposition of the other, but also the polymer is finely divided into a polymer blend. When dispersed, the reaction field becomes wider due to an increase in the interface between the polymers, and as a result, it is considered that this decomposition mechanism is further facilitated.

  In order to suppress the generation of this cracked gas, the conventional single polymer thermal decomposition suppression formulation is insufficient, and it is required to suppress thermal decomposition to a higher degree, like the decomposition inhibitor used in the present invention, It is important that the structure includes a phosphorus compound structure containing a phosphorus atom in one molecule and a hindered phenol structure at the same time.

  The hindered phenol structure has the function of suppressing or stopping the radical chain reaction by supplying electrons to radicals generated by thermal decomposition of polymers and oligomers. It is to suppress. Thereby, the progress of the thermal decomposition of the polymer can be suppressed, and the generation of decomposition gas can also be suppressed.

  However, when the above radical is an organic peroxide radical (R—O—O), R—O, which is an organic peroxide when hydrogen becomes a counter cation after electrons are donated in the hindered phenol structure. In some cases, -OH is generated, and an organic acid (ROOH) is generated from the -OH. Even if this is less than the case where there is no hindered phenol structure, the above-mentioned problems may not be sufficiently solved by the generation of the organic acid. Therefore, it is necessary to suppress the generation of peroxide radicals themselves, but organic radicals that are the basis of peroxide radicals may be generated by catalyst residues as well as heat. It is a phosphorus compound that suppresses this. Specifically, the phosphoric acid structure, phosphine structure, and phosphite structure can deactivate the catalyst residue and suppress the generation of organic radicals themselves, but the phosphine structure is particularly preferable from the viewpoint of the coordination ability to the catalyst residue. preferable. In addition, phosphorus compounds are also effective from the viewpoint of changing R—O—OH, which is a peroxide, to an alcohol instead of an organic acid. In this case, it is important that the phosphorus compound acts as a reducing agent, and trivalent phosphorus such as a phosphine structure or a phosphite structure is preferable.

  That is, if the hindered phenol structure is not present, the radical chain reaction cannot be stopped, and the reaction proceeds steadily, resulting in oxidation of low-molecular organic substances that are finally produced, resulting in the generation of a large amount of lower fatty acids. On the other hand, without the phosphorus compound structure, the generation of the original organic radical cannot be suppressed, or the reaction for generating the organic acid from the organic peroxide cannot be suppressed.

  The generation of organic radicals due to thermal decomposition of the polymer and the generation reaction of decomposition gas (especially lower fatty acids) resulting from this progress in the above-described reaction, and the reaction rate may be high. Therefore, it is important to have a hindered phenol structure and a phosphorus compound structure containing a phosphorus atom in the same molecule so that the generation of organic radicals, radical deactivation, and peroxide reduction can be performed in cooperation. That's it. Of these three mechanisms, the radical deactivation by the hindered phenol structure and the remaining two mechanisms or both may be combined, but the hindered phenol structure and the phosphate structure ( Molecules having three of pentavalent phosphorus) and a phosphine structure (trivalent phosphorus) or a phosphite structure (trivalent phosphorus) are difficult to obtain industrially and are expensive even if available. Therefore, a decomposition inhibitor having any one phosphorus compound structure selected from a hindered phenol structure, a phosphoric acid structure (pentavalent phosphorus), a phosphine structure (trivalent phosphorus) and a phosphite structure (trivalent phosphorus) is preferable. . In particular, from the viewpoint of suppressing the generation of organic radicals themselves, it is preferable to use a decomposition inhibitor composed of a hindered phenol structure and a phosphate structure.

  Aiming at the same effect, for example, as described in Patent Document 4, it may be possible to use a phosphorus compound and a hindered phenol compound in combination, but here, a phosphorus atom and a hindered phenol structure are present in one molecule. Therefore, it is difficult to efficiently suppress a radical chain reaction or a reaction from an organic radical to an organic acid with a high reaction rate. In addition, since each additive has a different melting point, it is difficult to add an additive to be added while weighing separately in the resin composition at the same abundance ratio because the reactivity varies depending on the temperature. It is very difficult to suppress the generation of cracked gas which is the object of the present invention.

  Moreover, when using a phosphorus compound and a hindered phenol type compound independently like patent document 2 and patent document 3, it cannot be overemphasized that the effect which suppresses generation | occurrence | production of decomposition gas becomes low, but it is independent. In some cases, the reaction of these additives may generate a component that can be a new decomposition gas as a side effect, which is not suitable for the purpose of the present invention.

  The addition amount of the decomposition inhibitor used in the present invention is set to a range of 0.01 to 1 mol% with respect to the entire resin composition as a range that can sufficiently react with polyamide and polylactic acid to suppress decomposition. is important. By adding 0.01 mol% or more of the decomposition inhibitor, the generation of decomposition gas (especially lower fatty acids, etc.) during melt molding can be suppressed, and corrosion and production on the piping of the melt processing equipment etc. The adverse environmental impact can be improved. On the other hand, by controlling the addition amount to 1 mol% or less, the island component can be finely dispersed without losing the viscosity balance between polyamide and polylactic acid, and excessive thickening of the blend polymer can be suppressed, resulting in excellent melt moldability. Can be obtained. In the present invention, the addition amount of the decomposition inhibitor is preferably 0.1 to 0.5 mol% as a range in which the effect of suppressing the generation of decomposition gas and the dispersion state of the island components are good.

  Usually, since the temperature at the time of melt-processing polyamide and polylactic acid is about 200 to 260 ° C., the melting point of additives such as decomposition inhibitors used in the present invention is below this temperature range, that is, 200 ° C. or below. It is preferable. However, if the melting point is too low, the handleability at the time of melt molding is poor, for example, the decomposition inhibitor itself may sublimate when adding a decomposition inhibitor or at the time of melt molding, and the generation of decomposition gas with respect to the addition amount. The suppression effect may be significantly reduced. For this reason, the melting point of the decomposition inhibitor used in the present invention is preferably 70 ° C. or higher. In order to advance the reaction with high efficiency during melt-kneading or melt spinning, the melting point of the decomposition inhibitor is 100 to 100 ° C. It is preferable that it is 150 degreeC. The melting point of the decomposition inhibitor referred to here means the peak top temperature of the melting peak observed by differential scanning calorimetry (DSC). As a specific measuring method, for example, the following can be performed. it can. That is, 10 mg of a sample is weighed, sealed in an aluminum pan, placed in a DSC, and measured at a temperature rising rate of 16 ° C./min. Then, at 2nd run, the peak top temperature of the melting peak of the additive is determined as the melting point of the polymer.

  The decomposition inhibitor used in the present invention has a structure containing a phosphorus atom and a hindered phenol structure in one molecule, and diethyl [[3,5-bis (1,1-dimethylethyl) -4-hydroxy. Phenyl] methyl] phosphonate and its metal salts, and 6- [3- (3-tert-butyl-4-hydroxy-5-methyl) proxy] -2,4,8,10-tetra-tert-butyldibenz [d, f] [1,3,2] -dioxaphosphine and the like, but diethyl [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] from the viewpoints of handleability and melting point ] Methyl] phosphonate is preferably used. Examples of diethyl [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] phosphonate include “IRGAMOD” (registered trademark) 295 manufactured by Ciba Chemical Specialty Co., Ltd. Since this decomposition inhibitor is a powder, it is easy to handle at the time of blending, and has an appropriate melting point for use in the present invention at 120 ° C., so that it can be suitably used.

  The composition ratio of polyamide and polylactic acid in the resin composition of the present invention is such that the polyamide to polylactic acid is inherently fragile polylactic acid and the toughness of the polyamide if the total amount of polyamide and polylactic acid is 100% by weight if the polyamide is 10% by weight or more. This is a preferred embodiment because a product having improved impact resistance, wear resistance and flexibility of the resin composition and improved defects of polylactic acid can be obtained. Moreover, if polyamide is 30 weight% or more, since the production | generation of the fine powder of a resin composition is suppressed and the handleability at the time of shaping | molding and a moldability improve, it is a more preferable aspect. In addition, when the total of polyamide and polylactic acid is 100% by weight, if the polyamide is 90% by weight or less, polylactic acid is preferable because it can suppress poor dimensional stability due to moisture absorption of the polyamide, and 70% by weight or less. If so, it is a more preferable embodiment.

  In the resin composition of the present invention, the polyamide and polylactic acid having a sea-island structure is a preferable embodiment from the viewpoint of combining the functions of different polymers (resins). This is because when the resin composition has a sea-island structure, the interface between the resins increases, so that it is difficult to peel off between the resins, and the durability of the resin composition and products made of them can be improved. The sea-island structure referred to in the present invention refers to a structure in which polyamide and polylactic acid have a phase separation structure, a major component or a low viscosity component becomes a sea component, and a minor component or a high viscosity component becomes an island component. In a polymer alloy system with relatively good compatibility, the island component is not a clear sea / island but has a layered structure, and it may be difficult to distinguish the sea / island, but it is phase-separated. In the present invention, it is included in the sea-island structure.

  Moreover, in this invention, it is preferable that the island component of said sea island structure is disperse | distributing finely. When the island components are finely dispersed, poor flow stability due to viscosity spots at the time of melt molding is reduced, and when the island components are refined, it is possible to expect new functions. Here, the fine dispersion means a state in which the average dispersion diameter of the island components is 1000 nm or less in the resin composition. For example, when the resin composition is spun and desealed, ultrafine fibers having an average fiber diameter of 1000 nm or less can be obtained, and a highly functional product can be obtained. As a feasible range, the lower limit of the average dispersion diameter of the island components is 10 nm or more.

  The average dispersion diameter mentioned here can be measured as follows. When the resin composition is in the form of pellets, after removing the sea component, the island component exposed from the SEM photograph was taken with a scanning electron microscope (SEM device) at a magnification allowing observation of 50 or more island component particles. The image processing software calculates 50 average diameters as circles or ellipses. This is performed at 3 or more locations, and the dispersion diameters of at least 150 island components are measured in total, and a simple number is calculated from the dispersion diameters. It can be obtained by calculating an average. The pellets referred to herein are those obtained by granulating the resin composition into small spherical shapes, cylindrical shapes, prismatic shapes, plate shapes, etc., each having a diameter or a side of about 1 to 20 mm. After making the discharged resin composition gut, it can be obtained by cutting using a cutter.

  On the other hand, when the resin composition is fibrous, 150 or more cross sections perpendicular to the fiber axis of the single yarn (single fiber) are measured with a transmission electron microscope (TEM apparatus) or a scanning electron microscope (SEM apparatus). Taken as a magnification to observe the island component. At this time, if necessary, metal staining can be applied to clarify the contrast of the sea islands. The diameters of 150 island components randomly extracted in the same image from the two-dimensionally photographed image are measured. Here, the island component appearing in the cross section perpendicular to the fiber axis is not necessarily a perfect circle, but if it is not a perfect circle, its area is measured, and a value obtained in terms of a circle is adopted. Moreover, about these values, it measures to the 1st decimal place in nm unit, and rounds off after the decimal point. In the present invention, the island component average diameter is obtained by measuring the diameters of 150 island components and obtaining a simple number average value thereof.

  In the present invention, when the sea component is polyamide, polyamide excellent in toughness, abrasion resistance and chemical resistance appears on the surface of the resin composition, so that the impact resistance and flexibility of the resin composition are increased. , Wear resistance and chemical resistance are improved. On the other hand, when the sea component is polylactic acid, polylactic acid with low hygroscopicity coats the polyamide, so that dimensional stability failure due to moisture absorption of the polyamide is suppressed, and the dimensional stability of the resin composition and its molded product is reduced. improves.

  Next, the manufacturing method of the resin composition of this invention is demonstrated. The resin composition of the present invention is a method in which polyamide, polylactic acid, and a decomposition inhibitor are melt-mixed by an extruder or kneader, and a solid material is mechanically uniformly mixed and then directly molded simultaneously with mixing. , And a method in which an additive is directly put into a polymerization can of the resin and mixed, etc., and the like.

  Specifically, for example, when polyamide, polylactic acid, and a decomposition inhibitor are separately weighed and inserted into a twin-screw kneader and the screw diameter is 37 mmφ and L / D = 48, the kneading temperature is 220 to 240. The resin composition of the present invention can be stably obtained by setting the temperature to 0 ° C., the discharge rate of 5 to 50 kg / hour, and the screw rotation speed of 100 to 400 rpm. At this time, when the screw diameter is larger than 37 mmφ or L / D is smaller than 48, it is preferable to increase the screw rotation speed in order to strengthen the kneading, and to suppress the decomposition by strengthening the kneading. In addition to reducing blend unevenness of the agent, it is also effective for fine dispersion of island components.

  The order of addition of the respective components at this time may be arbitrary, but it is preferable to first mix a decomposition inhibitor, and for example, it can be dry blended beforehand with polyamide and / or polylactic acid. This is because generation of radicals at the initial stage of kneading and generation of components that can be radical initiators such as peroxides can be suppressed.

  The resin composition of the present invention has a sea-island structure in which polyamide or polylactic acid is a sea component or island component. When the ratio of polyamide / polylactic acid is 10/90 to 50/50, polyamide is used. Is necessary because the sea component and the island component are determined by the kneading ratio of the polyamide and polylactic acid so that the polylactic acid becomes the island component when the ratio of polyamide / polylactic acid is 60/40 to 90/10. It can be adjusted according to the characteristics.

  To the resin composition of the present invention, various additives other than the decomposition inhibitor having a structure in which the molecular structure simultaneously contains a phosphorus atom and a hindered phenol structure in one molecule are added within a range that does not impair the object of the present invention. be able to. For example, molding aids such as crystal nucleating agents and lubricants, UV absorbers, hydrolysis resistance improvers, colorants such as pigments and dyes, foaming agents, antistatic agents, conductive agents, flame retardants, reinforcing agents, fillers, A plasticizer, a compatibilizer, a thickener and the like can optionally be contained.

  The resin composition of the present invention can contain a filler or the like according to the application within a range not impairing the object of the present invention, but when used for melt spinning, clogging of spinneret holes and pack pressure are possible. Since continuous operation becomes difficult due to the increase, the blending amount of the filler and the like is preferably less than 0.1% by weight.

  The resin composition of the present invention may contain other thermoplastic resins as long as the object of the present invention is not impaired. Examples of other thermoplastic resins include polyethylene, polypropylene, acrylic, polyphenylene sulfide, polyesters other than polylactic acid, polyimide, and polyetherimide. However, when the melting point of the other thermoplastic resin is high, it is necessary to raise the melting temperature unnecessarily at the time of melt molding, which may accelerate the decomposition. A thermoplastic resin of ˜280 ° C. is preferred.

  When the resin composition of the present invention thus obtained is made into a fiber by an ordinary melt spinning method, the resin composition can be once pelletized and then melted and spun again. The resin composition melt-mixed by directly connecting an extruder to the machine can be melt-spun as it is. This spinning machine can be spun by a known melt spinning machine, but the spinning temperature is preferably higher by 10 ° C. or more than polylactic acid alone, specifically 210-280. It is preferable to make it into the range of ° C.

  In the case of a blend polymer, compared to the case of a single resin (polymer), a ballast phenomenon in which the polymer flow instantly swells after melt discharge is likely to occur, and in order to reduce the influence of the ballast, a spinning temperature of 230 ° C. or higher. However, in a simple polymer blend of polyamide and polylactic acid, the temperature is such that decomposition gas is remarkably generated.

  With respect to the resin composition of the present invention, the generation of cracked gas is greatly suppressed, so that the spinning can be performed without deteriorating the production environment even at this spinning temperature, and the progress of corrosion of the piping of the spinning machine is suppressed. be able to. The cracked gas generated during spinning oozes out from the piping and metering section of the spinning machine, corroding the outside of the spinning machine's piping, and if it progresses excessively, the spinning machine is damaged, making continuous operation difficult. However, in the resin composition of the present invention, these influences are remarkably reduced, and the ripple effect is very large considering industrialization.

  The spinning speed when melt spinning the resin composition of the present invention is preferably in the range of 200 to 6000 m / min from the viewpoint of suppressing fluctuations in the ballast position accompanying an increase in spinning tension. In addition, the obtained fiber may be drawn once for the purpose of reducing the fineness and improving the mechanical properties, or may be drawn by a drawing apparatus having a pair of known heating rollers continuously after spinning. it can.

  The stretching temperature and the heat treatment temperature are preferably 60 to 100 ° C. and the heat treatment temperature is preferably 100 to 150 ° C. as a condition for obtaining good stretchability. The draw ratio needs to be changed using the elongation of the undrawn yarn as a guideline. Considering the handleability of the fiber and the processability in the subsequent process, the draw ratio is such that the elongation of the drawn yarn is 10 to 50%. Is preferably set.

  Regarding the cross-sectional shape of the fiber, a round cross-section, a hollow cross-section, a multi-leaf cross-section such as a trilobal cross-section, and other irregular cross-sections can be freely selected. The form of the fibers can be any of long fibers and short fibers, and in the case of long fibers, it may be multifilament or monofilament.

  In addition, the resin composition of the present invention can be directly made into a fiber web (long fiber nonwoven fabric or the like) by a spun bond or a melt blow method. Among them, the spunbond method is preferably used from the viewpoint of improvement in tensile strength of the fiber web and production cost. The spunbond method as used herein generally refers to extruding a molten polymer from a nozzle, drawing it at a speed of 2500 to 8000 m / min with a high-speed suction gas, and then collecting the fibers on a moving conveyor to obtain a fiber web And say how. Also in the spunbond method, the melting temperature is preferably 210 to 280 ° C, and within this range, a fiber web can be stably obtained.

Further, following the collection of the fiber web, an integrated sheet-like material can be obtained by performing thermal bonding or entanglement. The entanglement method of the fiber web can be performed, for example, by needle punching or water jet punching alone or in combination.
The number of needle punching punches is preferably 500 to 3000 / cm ² for the purpose of achieving a dense surface state by high entanglement of fibers. If the number of punching is 500 / cm ² or more, the fineness of the surface fiber becomes good and a desired high-precision finish can be obtained. If the number of punching is 3000 / cm ² or less, the workability is deteriorated. Fiber damage that leads to strength reduction is suppressed without incurring. Moreover, when performing a water jet punching process, it is preferable to perform water in the state of a columnar flow, and the columnar flow normally ejected at a pressure of 1 to 60 MPa from a nozzle having a diameter of 0.05 to 1.0 mm is preferably used. It is done.

  The ultrafine fiber can be obtained by dissolving and removing the sea component from the fiber comprising the resin composition of the present invention or the fiber structure thereof, and the porous fiber can be obtained by dissolving and removing the island component. When removing polylactic acid, an alkali such as a sodium hydroxide aqueous solution is used, and when dissolving and removing polyamide, formic acid or the like may be used. As a treatment method, the fiber or the fiber structure may be used, and then immersed in an alkaline aqueous solution or formic acid. In addition, this dissolution and removal treatment can be carried out in a large amount at a time by using a known liquid dyeing machine, a zicker dyeing machine, etc., so that productivity is good and a preferred embodiment from an industrial viewpoint. It is.

  The fiber structure in the present invention refers to various fiber products such as woven fabrics, knitted fabrics, spunbonds, melt blows, spunlaces, and other non-woven fabrics such as cups and boards, and the resin of the present invention. The fibers obtained from the composition, or the ultra-fine fibers and porous fibers generated from the fibers, can be used not only for clothing such as shirts, blousons, pants, coats and artificial leather, but also for cups, pads, etc. It can be used for various uses such as clothing material use, interior use such as curtains, carpets, mats and furniture, industrial material use such as wiping cloth, polishing cloth and filter, and vehicle interior use.

  The resin composition of the present invention can be processed and used for various molded products by methods such as injection molding and extrusion molding as well as fibers. The molded product can be used as an injection molded product, an extrusion molded product, a blow molded product, a film, a sheet, and the like.

  EXAMPLES Hereinafter, although an Example is given and the resin composition of this invention is demonstrated in detail, this invention is not limited to these. About the measuring method in an Example, the following method was used.

A. Melt Viscosity of Resin (Polymer) The melt viscosity of the polymer was measured at a desired speed using a Capillograph 1B manufactured by Toyo Seiki. The polymer storage time from the insertion of the chip to the start of measurement was measured for 4 minutes in a nitrogen atmosphere.

B. Measurement of generation amount of cracked gas of resin composition In a glass container filled with helium gas, the chip is heated from a temperature of 50 ° C. to a temperature of 250 ° C. at a temperature of 10 ° C./min, and kept at a temperature of 250 ° C. for 30 minutes. The components generated at this time are collected in an activated carbon collection tube (manufactured by Spelco: carbon trap 400). This collection tube was heated at a temperature of 300 ° C., the collected components were desorbed, introduced into Automass SUN-200 GC / MS manufactured by JEOL Ltd., and the components and the amount of generation were analyzed (CG / MS column: GL Science). CP-WAX52CB 25 m × 0.32 mm manufactured by Co., Ltd.). The generated amount per unit weight was calculated by dividing the obtained generated amount by the weight of the resin composition. Of the components contained in the cracked gas, attention is paid particularly to acetic acid and propionic acid, which have a great influence on odor and metal corrosion, and as a cracked gas suppression effect of the present invention, an unadded sample in the cracked gas (see Reference Example 1 described later). 50% of the numerical value obtained in the above, that is, the case where the amount of acetic acid in the cracked gas is 15.0 mg / kg or less and the amount of propionic acid is 7.0 mg / kg or less was regarded as an acceptable level.

C. Evaluation of Odor Generation of Resin Composition 0.5 g of a chip is weighed and introduced into a test tube, then slightly pressurized with nitrogen, heated in an oil bath heated to a temperature of 250 ° C. for 30 minutes, and immediately above the molten chip From this, 5 ml of decomposition gas was collected with a syringe. The collected cracked gas was measured with an odor sensor (portable monitor OD-85 manufactured by Riken Keiki Co., Ltd.), the displayed numerical value was measured three times, and the odor suppression rate was calculated based on the following formula. As an odor suppressing effect, an acceptable level was obtained when this value was less than 80%.
・ Odor control rate = (number of samples added / number of samples not added) × 100 (%)
The added sample represents a sample containing a decomposition inhibitor (used in Examples and Comparative Examples), and the non-added sample represents a sample containing no decomposition inhibitor (used in Reference Example 1 for pellets and Reference Example 4 for spinning).

D. Melting | fusing point of resin and additive Using TA Instruments DSC2920 Modulated DSC, the peak top temperature which shows melting | fusing of a polymer by 2nd run was made into melting | fusing point of a polymer. The temperature rising rate at this time was 16 ° C./min, and the sample amount was 10 mg.

E. Island component / average dispersion diameter of pellets Remove the sea component of the pellet-shaped resin composition, and after washing with water, photographed at a magnification at which 50 or more island components can be observed with a VE-7800 type SEM device manufactured by Keyence Corporation. The island component exposed from the SEM photograph is obtained by image processing software (“Win · ROOF” (registered trademark)) to obtain 50 average diameters as a circle or an ellipse. It was determined by measuring the dispersion diameter of one or more island components. The diameter of each island component polymer is measured in nm to one decimal place and rounded off to the nearest decimal place. A simple number average value was obtained from the dispersion diameter. A 5000 × photograph was used for the measurement.

F. Average diameter of island component of fiber Cut out ultra-thin slice of fiber, and observed 150 or more island components in a cross section perpendicular to the fiber axis of single fiber with H-7100FA transmission electron microscope (TEM apparatus) manufactured by Hitachi Shoot as much as possible. From the images photographed two-dimensionally, the diameters of 150 island components randomly extracted in the same image were measured. Here, the island component appearing in the cross section perpendicular to the fiber axis is not necessarily a perfect circle, but when it is not a perfect circle, its area was measured and a value obtained in terms of a circle was adopted. Moreover, about these values, it measured to the 1st decimal place in nm unit, and calculated | required by rounding off after the decimal point. Moreover, the diameter of each 150 pieces was measured and the simple number average value was calculated | required as an island component average diameter. In addition, the photo of 50000 times was used for the measurement.

G. Fiber Strength The fineness (dtex) was calculated by setting the diameter to 100 m using an intec corporation measuring scale and multiplying the weight by 100. Using a tensile tester “TENSILON” (registered trademark) UCT-100 manufactured by Orientec Co., Ltd., a stress-strain curve is measured under the conditions of a sample length of 20 cm and a tensile speed of 100% / min. The breaking strength is calculated by reading the load at break and dividing the load by the initial fineness. Further, the elongation at break is calculated by reading the strain at break and multiplying the value divided by the sample length by 100. This was repeated 5 times or more, and a simple number average of the obtained results was obtained to obtain an average strength and an average elongation.

(Reference Example 1)
Nylon 6 having a melt viscosity of 190 Pa · s (230 ° C., 1216 sec ⁻¹ ) and a melting point of 228 ° C. and polylactic acid having a melt viscosity of 67 Pa · s (230 ° C., 1216 sec ⁻¹ ) and a melting point of 170 ° C. The bilactic kneader (screw diameter: 37 mmφ L / D: 48), which was independently weighed so that the polylactic acid was 60% by weight, and these were set at a kneading temperature of 220 ° C., a screw rotation speed of 300 rpm, and a discharge rate of 15 kg / hour. ) To obtain a resin composition.

The melt viscosity of the obtained resin composition was 85 Pa · s (230 ° C., 1216 sec ⁻¹ ), and the average dispersion diameter of nylon 6 as an island component was 600 nm. When the decomposition gas component of this resin composition was analyzed, mainly lower fatty acids (acetic acid, propionic acid and acrylic acid), 2,3-pentanedione and ε-caprolactam were detected. The amount of each generated is shown in Table 1. In Reference Example 1, the acetic acid amount was 29.4 mg / kg and the propionic acid amount was 14.6 mg / kg, which were high values, compared with Reference Example 2 (nylon 6 alone) and Reference Example 3 (polylactic acid alone). Thus, it can be seen that the decomposition gas generation amount is greatly increased, and the decomposition is promoted by blending nylon 6 and polylactic acid so that the decomposition products of each other decompose each other. Moreover, the numerical value displayed by the odor sensor in the odor evaluation was as high as 776 because a large amount of lower fatty acid was generated.

(Reference Example 2)
All were carried out in accordance with Reference Example 1 except that no polylactic acid resin was added and nylon 6 was 100% by weight. Polymer properties including cracked gas and odor evaluation are as shown in Table 1. In this case, generation of acetic acid and propionic acid, which are lower fatty acids, was not confirmed, and the amount of ε-caprolactam derived from nylon 6 was also generated. Was 244.9 mg / kg, which was about 50% lower than that of Reference Example 1.

(Reference Example 3)
All were carried out according to Reference Example 1 except that nylon 6 was not added and polylactic acid was 100% by weight. Polymer properties including cracked gas and odor evaluation are as shown in Table 1. Generation of ε-caprolactam derived from nylon 6 was not confirmed, and the amount of acetic acid as a lower fatty acid was 12.0 mg / kg, the amount of propionic acid Was 5.5 mg / kg, a decrease of 50% or more compared to Reference Example 1.

[Decomposition gas component / evaluation]: Pass ○ Fail × [Odor evaluation]: Pass ○ Fail ×
[Example 1]
As a decomposition inhibitor having a structure in which polylactic acid contains a phosphorus atom and a hindered phenol structure in one molecule before introduction into a biaxial kneader, the following chemical formula 1

Reference Example 1 except that “IRGAMOD” (registered trademark) 295 (melting point: 120 ° C.) manufactured by Ciba Chemical Specialty Co., Ltd. is dry blended to 0.12 mol% (0.5 wt%). It carried out according to.

The obtained resin composition has a melt viscosity of 85 Pa · s (230 ° C., 1216 sec ⁻¹ ), and the average dispersion diameter of nylon 6 as an island component is 620 nm. I couldn't. When the decomposition gas component of this resin composition was analyzed, the amount of acetic acid was 10.6 mg / kg and the amount of propionic acid was 3.9 mg / kg, which was significantly suppressed as compared to Reference Example 1 (pass). The odor evaluation (odor sensor value: 403) was also suppressed to 52% and passed. The results are shown in Table 2.

(Comparative Example 1)
The additive is represented by the following chemical formula 2

Except for the change to “ADEKA STAB” (registered trademark) AX-71 (phosphate compound, melting point 70 ° C., addition amount 0.12 mol% (0.7 wt%)) manufactured by Adeka Co., Ltd. did.

The melt viscosity of the obtained resin composition is 83 Pa · s (230 ° C., 1216 sec ⁻¹ ), the average dispersion diameter of nylon 6 as an island component is 720 nm, and the average dispersion diameter of the island component is increased. From the viewpoint of fine dispersion of the components, it was inferior to Example 1. The decomposition gas component of this resin composition was analyzed. The amount of acetic acid was 49.2 mg / kg, the amount of propionic acid was 15.6 mg / kg, and the amount generated was increased compared to Reference Example 1, It was a failure. Further, the odor evaluation (odor sensor value: 931) was also rejected as 120%, and the addition of a phosphoric acid compound alone resulted in an increase in odor.

  The additive having only the phosphoric acid structure used in Comparative Example 1 suppresses the generation of organic radicals by deactivating the catalyst as described in Patent Document 3, and the melt viscosity retention ratio at the time of melting is improved. However, it was not effective in suppressing the generation of cracked gas due to the lack of a function to stop the chain reaction of the generated radicals and the lack of a function of reducing organic peroxides or a function of inhibiting decomposition of decomposition products. Inferred. The results are shown in Table 2.

(Comparative Example 2)
The additive is represented by the following chemical formula 3

In order to make the hindered phenol structure the same amount as in Example 1 with “IRGANOX” (registered trademark) 1010 (hindered phenol compound melting point 110 ° C.) manufactured by Ciba Chemical Specialty Co., Ltd. All were carried out in accordance with Example 1 except that the content was 0.05 mol% (0.7 wt%).

The melt viscosity of the obtained resin composition is 85 Pa · s (230 ° C., 1216 sec ⁻¹ ), the average dispersion diameter of nylon 6 as an island component is 610 nm, and the influence of the additive on the polymer properties is observed. There wasn't. The decomposition gas component of this resin composition was analyzed, but although the acetic acid amount was 19.8 mg / kg and the propionic acid amount was 8.3 mg / kg, there was an inhibitory effect, but the acceptable level was not reached, and the odor evaluation (odor) The sensor numerical value: 737) was also slightly reduced to 95%, which was a result that did not reach Example 1 of the present invention in terms of the effect of suppressing decomposition and odor.

  Since the additive having only the hindered phenol structure used in Comparative Example 2 has a function of stopping or suppressing the chain reaction of the generated organic radical, generation of cracked gas is generated as compared with the case of not adding (Reference Example 1). However, the effect is lower than that of Example 1 of the present invention because it does not have the function of suppressing the generation of organic radicals itself or the function of reducing the generated organic peroxide. It is presumed that The results are shown in Table 2.

(Comparative Example 3)
As an additive, the phosphorus compound used in Comparative Example 1 and the hindered phenol compound used in Comparative Example 2 are used in combination, and the phosphorus compound is 0.13 mol% (0.7 wt%), the hindered phenol compound. Was carried out according to Example 1 except that was added as 0.05 mol% (0.6 wt%).

The melt viscosity of the obtained resin composition is 86 Pa · s (230 ° C., 1216 sec ⁻¹ ), the average dispersion diameter of nylon 6 as an island component is 698 nm, and the island component expands due to the addition of the phosphorus compound. It was seen. The decomposition gas component of this resin composition was analyzed. The amount of acetic acid was 22.7 mg / kg and the amount of propionic acid was 7.3 mg / kg. It was a result. Odor evaluation (smell sensor value: 629) was 81%, slightly exceeding the standard, and as a result, the gas analysis and odor evaluation were rejected.

  In Comparative Example 3, the hindered phenolic compound and the phosphoric acid compound were used as independent molecules, but their synergistic effects could not be exerted because they did not have the same structure in the same molecule. It is presumed that the effect of suppressing the proceeding radical chain reaction is low, which is inferior to that of Example 1 of the present invention. The results are shown in Table 2.

Additive A: “IRGAMOD” (registered trademark) 295 chemical formula 1 manufactured by Ciba Chemical Specialty Co., Ltd.
Additive B: Adeka Corporation ADEKA STAB AX-71 Chemical Formula 2 (phosphorus compound)
Additive C: “IRGANOX” (registered trademark) 1010 manufactured by Ciba Chemical Specialty Co., Ltd. Chemical formula 3 (hindered phenol compound)
[Decomposition gas component / evaluation]: Pass ○ Fail × [Odor evaluation]: Pass ○ Fail ×
[Examples 2 to 4]
Example 1 except that the addition amount of the decomposition inhibitor was 0.01 mol% (0.05 wt%), 0.03 mol% (0.1 wt%), and 1.0 mol% (4 wt%). It carried out according to. Table 3 shows the polymer properties, decomposition gas generation amount, and odor evaluation results of the obtained resin composition.

  With the increase in the amount of decomposition inhibitor added, the amount of cracked gas generation and odor evaluation improved, and even with 0.01 mol% added, the amount of acetic acid was 14.5 mg / kg and the amount of propionic acid was 6.8 mg / kg. Compared to Example 1, it was suppressed by about 50%, and the odor evaluation was 76%, which was a pass level. Moreover, about 1.0 mol% addition, the acetic acid amount further decreased to 10.1 mg / kg and the propionic acid amount 4.4 mg / kg, and the odor was greatly suppressed to 48% in the odor evaluation.

[Example 5]
The same procedure as in Example 1 was performed except that the kneading ratio of nylon 6 and polylactic acid was 20 wt% and 80 wt%, and the decomposition inhibitor was 0.13 mol% (0.5 wt%).

  The components in the cracked gas of the resin composition thus obtained were 13.5 mg / kg for acetic acid and 5.8 mg / kg for propionic acid, which were as low as in Example 1. In addition, the odor evaluation reaches 65%, which is an acceptable level, and it was found that the odor evaluation is also effective in a resin composition rich in polylactic acid. The results are shown in Table 3.

[Example 6]
The same procedure as in Example 1 was performed except that the kneading ratio of nylon 6 and polylactic acid was 60 wt% and 40 wt%, and the decomposition inhibitor was 0.13 mol% (0.5 wt%).

  In the obtained resin composition, the sea-island component was reversed as compared with Example 1, and the sea component was nylon 6. The components in the decomposition gas of this resin composition had an acetic acid amount of 12.1 mg / kg and a propionic acid amount of 4.8 mg / kg, which were low values as in Example 1. Further, the odor evaluation reached 56%, which was an acceptable level, and it was found that the odor evaluation is also effective in a nylon 6-rich resin composition. The results are shown in Table 3.

Additive A: “IRGAMOD” (registered trademark) 295 chemical formula 1 manufactured by Ciba Chemical Specialty Co., Ltd.
[Decomposition gas component / evaluation]: Pass ○ Fail × [Odor evaluation]: Pass ○ Fail ×
(Reference Example 4)
Using the pellets prepared in Reference Example 1, melt spinning was performed at a spinning temperature of 240 ° C. It measured so that it might become a single hole discharge amount 0.85g / min, and it discharged from 0.35mm (phi) (L / D = 2.0) -36 hole nozzle | capacitance (residence time until discharge: 25 minutes). The melted and discharged resin was cooled and solidified, and after the oil agent was adhered, it was wound up at a spinning speed of 1350 m / min. The obtained undrawn yarn was subjected to heat treatment at a draw ratio of 2.1 times with the temperature of the first hot roller being 90 ° C. and the temperature of the second hot roller being 130 ° C., and the mechanical properties of the obtained drawn yarn were measured. However, the strength was 1.7 cN / dtex. The island component average diameter seen in the fiber cross section of the obtained drawn yarn was 100 nm, and a sea-island type composite fiber in which the island component was refined was obtained.

  As an indication of the amount of cracked gas generated, an odor sensor (portable monitor OD-85 manufactured by Riken Keiki Co., Ltd.) using the odor just below the base for odor evaluation was evaluated, and the displayed numerical value was 854. In addition, after spinning continuously for 24 hours under the above-mentioned conditions, the spinning was completed, the melt spinning machine was cooled, the temperature was raised again, and disassembling and the spinning machine piping and measuring section were checked. A wide range of metal corrosion was observed at the joints and shafts of the measuring section.

[Example 7]
All were carried out according to Reference Example 4 except that the pellets prepared in Example 1 were used. When the mechanical properties of the obtained drawn yarn were measured, the strength was 2 cN / dtex or more, and the strength was slightly increased as compared with Reference Example 4. The island component average diameter found in the fiber cross section of the obtained drawn yarn was 100 nm, and as in Reference Example 4, a sea-island composite fiber in which the island component was refined was obtained.

  When the odor just below the spinneret was evaluated in the same manner as in Reference Example 2, the displayed value of the odor sensor was 555, and the odor was suppressed by 35%. In addition, after spinning for 24 hours continuously, after cooling the melt spinning machine, the temperature was raised again by heating, disassembling and checking the piping and measuring section of the spinning machine, almost no metal corrosion was observed in the piping and measuring section. I couldn't.

(Comparative Examples 4-6)
All were performed according to Reference Example 2 except that the pellets prepared in Comparative Examples 1 to 3 were used. When the odor just below the spinneret was evaluated in the same manner as in Reference Example 2, the display value of the odor sensor was 982 in Comparative Example 4 using a phosphorus compound, and conversely, the odor increased by 15%. Comparative Examples 5 and 6 However, although the display value of the odor sensor was 794 and 768 and a slight suppression effect was seen, the effect was hardly seen. The corrosion of the spinning machine was almost the same as in Reference Example 2, and was far from the effect of the resin composition of the present invention.

Claims (6)

  A resin composition comprising polyamide, polylactic acid and a decomposition inhibitor, wherein the decomposition inhibitor has a molecular structure containing a phosphorus atom and a hindered phenol structure simultaneously in one molecule, A resin composition characterized by being added in an amount of 0.01 to 1 mol% with respect to the entire resin composition.   The resin composition according to claim 1, wherein the content of the polyamide is 10 to 90% by weight with respect to the entire resin composition.   3. The resin composition according to claim 1, wherein the polyamide and polylactic acid form a sea-island structure, and an average dispersion diameter of island components of the sea-island structure is 10 to 1000 nm.   A fiber comprising the resin composition according to any one of claims 1 to 3.   A fiber structure comprising the fiber according to claim 4.   A method for producing a fiber, comprising melt-spinning the resin composition according to any one of claims 1 to 3.