Polyamide resin composition

Abstract

This invention provides a polyamide resin composition that serves as a raw material for bio-based polyamide fibers, exhibiting excellent quality in terms of color tone and strength, as well as superior high-order passability. [Solution] A polyamide resin composition comprising a diamine component and sebacic acid, wherein the content of metal sulfate salts, which are inorganic particulate components, is 1000 ppm or less, and the bio-based carbon concentration is 50% or more.

Description

Technical Field

[0001] The present invention relates to a polyamide resin composition obtained by polycondensing a diamine component and sebacic acid, which has excellent spinning operability.

Background Art

[0002] Thermoplastic resins such as polyamides and polyesters are widely used as clothing fibers, industrial fibers or resin molding applications, and are excellent in strength, durability and heat resistance. In recent years, due to the increasing awareness of sustainable society, activities to replace petroleum-based raw materials have become active, and non-petroleum raw materials are also required for polyamide fibers.

[0003] In particular, in apparel brands that lead the activities to replace petroleum-based raw materials, the demand for biomass materials in clothing applications such as outdoor jackets, sportswear, and inners, which are the central products using polyamide fibers, is high. Due to the increasing demand for soft-touch, lightweight, and pocketable materials, fibers with a finer single-filament fineness and higher strength are required.

[0004] Under such circumstances, a biomass-derived polyamide resin composition from which high-quality fibers can be obtained is desired. Among them, polyamide obtained by polycondensing diamine and sebacic acid has sebacic acid generally being a biomass-derived component, and strength, durability, and heat resistance not inferior to those of general-purpose petroleum-derived polyamides such as polyhexamethylene adipamide (N66) and polycapramide (N6). Therefore, the demand for environmentally friendly polyamide resins is increasing, and they are also widely used in fiber applications.

[0005] As a method for producing a biomass-derived polyamide resin composition, for example, in Patent Document 1, a polyamide resin composed of adipic acid and biomass-derived 1,5-pentanediamine is extracted with high-temperature hot water to reduce the amounts of monomer and oligomer components contained in the polyamide resin, and a polyamide resin composition that is a raw material for high-quality, high-grade, and operable polyamide fibers is provided.

[0006] Furthermore, Patent Document 2 provides a polyamide resin composition comprising a diamine component and biomass-derived sebacic acid, in which the amount of amino-terminal groups that serve as dyeing sites for acid dyes is sufficiently large, and thermal degradation is suppressed by optimizing the polymerization temperature, time, and pressure, thereby providing a polyamide resin composition with excellent dyeability and spinning operability. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Special Publication No. 2024-521432 [Patent Document 2] International Publication No. 2022 / 202535 Brochure [Overview of the project] [Problems that the invention aims to solve]

[0008] However, biomass-derived sebacic acid retains a large amount of inorganic particulate matter, and highly bio-based polyamide resin compositions obtained by polycondensation of diamine components and sebacic acid also have a high inorganic particulate matter content. Furthermore, inorganic particles tend to coarseen and aggregate, and when used in fibers, the retention of such coarse inorganic particles in the fibers makes the yarn prone to fuzzing and breakage, as well as causing a decrease in strength.

[0009] The high-temperature hot water extraction method described in Patent Document 1 extracts polyamide resin at a hot water extraction temperature in the range of 80°C to 140°C, allowing for the removal of inorganic particles in addition to monomers and oligomer components. However, due to the high extraction temperature, the polymer is significantly affected by thermal degradation, resulting in poor color. Even after fiberization, the color remains poor, leading to a decline in quality. The method described in Patent Document 2, while capable of suppressing the formation of microgels and the like due to thermal degradation by optimizing polymerization temperature, time, and pressure, was insufficient in removing inorganic particles. Therefore, due to the influence of coarse inorganic particles still remaining in the polymer, operational deterioration such as a rapid increase in pack pressure due to filter clogging and an increase in yarn breakage is observed during melt spinning. Furthermore, even after fiberization, the remaining coarse inorganic particles cause fuzzing and a decrease in strength, resulting in a decline in quality.

[0010] Thus, even using conventional methods for producing biomass-derived polyamide resin compositions, it was difficult to obtain a high-quality biomass-derived polyamide resin composition with excellent spinning operability, which was obtained by polycondensation of a diamine component and sebacic acid.

[0011] Therefore, the present invention aims to solve the above problems and to obtain a biomass-derived polyamide resin composition that is of high quality and has excellent spinning operability when a polyamide resin obtained by polycondensation of a diamine component and sebacic acid is made into fibers.

[0012] Through diligent investigation into the aforementioned problem, we discovered that the inorganic particulate components contained in sebacic acid include metal sulfate salts, which are by-products generated during the manufacturing process of sebacic acid, and thus arrived at the present invention. [Means for solving the problem]

[0013] The present invention, which solves the above problems, has the following configuration. (1) A polyamide resin composition comprising a diamine component and sebacic acid, wherein the content of metal sulfate salts, which are inorganic particulate components, is 1000 ppm or less, and the bio-based carbon concentration is 50% or more. (2) The polyamide resin composition according to (1), wherein the metal component of the metal sulfate salt is sodium or potassium. (3) The polyamide resin composition according to (1) or (2), wherein the degree of yellowing YI of the pellets of the polyamide resin composition is 6.0 or less. [Effects of the Invention]

[0014] The polyamide resin composition of the present invention can provide fine-denier, high-strength biomass-derived polyamide fibers with excellent spinning operation properties and superior color tone. [Modes for carrying out the invention]

[0015] The present invention relates to a polyamide resin composition obtained by polycondensation of a diamine component and sebaciic acid. The polyamide resin composition of the present invention is preferably a polyamide resin composition in which 90 mol% or more of the repeating units are composed of sebacic acid units. A high content of sebacic acid units facilitates oriented crystallization during the spinning process, thereby increasing the regularity of the molecular chains of the resulting fibers, resulting in fibers with excellent mechanical properties, boiling water shrinkage rate, and heat resistance. The ratio of sebacic acid units is more preferably 95 mol% or more, and even more preferably 98 mol% or more.

[0016] Furthermore, while sebacic acid can be derived from petroleum or from biomass such as plants, in this invention, it is preferable to use sebacic acid obtained from biomass such as castor oil, which is a plant-derived raw material.

[0017] Furthermore, within a range that does not impair the effects of the present invention, the mixture may contain, for example, 10 mol% or less of dicarboxylic acid components other than sebacic acid. Other dicarboxylic acids are not particularly limited, but include aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, undecanediic acid, dodecanediic acid, brassic acid, tetradecanediic acid, pentadecanediic acid, and octadecanediic acid, as well as aromatic dicarboxylic acids such as cyclohexanedicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, and naphthalenedicarboxylic acid.

[0018] The diamine component of the present invention includes, for example, aliphatic diamines such as ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane, 1,13-diaminotridecane, 1,14-diaminotetradecane, 1,15-diaminopentadecane, 1,16-diaminohexadecane, 1,17-diaminoheptadecane, 1,18-diaminooctadecane, 1,19-diaminononadecane, 1,20-diaminoeicosane, 2-methyl-1,5-diaminopentane; alicyclic diamines such as cyclohexanediamine, bis-(4-aminohexyl)methane; aromatic diamines such as xylylenediamine, etc.

[0019] Either one type of diamine component or two or more types of diamine components may be used. When mixing a plurality of diamine components, the main diamine component is preferably 90 mol% or more of the repeating unit with respect to the total of the sub-diamine components. By setting it within this range, it becomes easier to perform orientation crystallization in the spinning process, so the regularity of the molecular chains of the obtained fibers increases, resulting in fibers excellent in mechanical properties, boiling water shrinkage rate, and further heat resistance. The ratio of the main diamine unit is more preferably 95 mol% or more, and even more preferably 98 mol% or more.

[0020] When the polyamide resin composition of the present invention is used for clothing fibers, industrial fibers, or resin molding applications, from the viewpoints of processability and heat resistance, the melting point of the polymer is preferably 200 to 300 °C, and it is preferable to select a diamine component such that it falls within this range. To obtain a polymer within this melting point range, the diamine component is preferably 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,10-diaminodecane. Further, from the ease of industrial availability, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane are more preferable.

[0021] In addition, the polyamide resin composition in the present invention can contain structural units derived from amino acids such as 6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, and para-aminomethylbenzoic acid, and lactams such as ε-caprolactam and ω-laurolactam, as long as the effects of the present invention are not impaired.

[0022] As described above, with the depletion of petroleum resources and global warming being regarded as problems, and efforts being made on a global scale to address environmental issues, products using raw materials that consider the environment and do not rely on petroleum resources are required to be biomass-derived, and further to have a high bio-based degree considering the contribution to the global environment.

[0023] In the polyamide resin composition of the present invention, the bio-based carbon concentration calculated from the measured value of radioactive carbon (14C) is 50% or more of the total carbon mass constituting the polyamide resin composition. A more preferable bio-based carbon concentration is 80% or more, and even more preferably 100%.

[0024] By setting the bio-based carbon concentration within such a range, an effect of suppressing the emission amount of carbon dioxide emitted during polyamide production can be expected. As a result, the generation of carbon dioxide during the production of polyamide multifilament can be suppressed.

[0025] Here, the bio-based carbon concentration will be explained. Generally, if the production methods of a resin composition derived from vegetable raw materials and a resin composition derived from petroleum are the same, there are no differences in mechanical properties such as molecular weight and crystallinity, which are caused by the structure of the polymer, and thermal properties such as melting point, which are due to the structure of the polymer. To distinguish between raw material origins, the bio-based carbon concentration, which can be calculated by measuring the content of the radioactive isotope 14C, is used. Since plants absorb atmospheric 14C along with carbon dioxide during their growth, 14C is contained only in plant-based raw materials. On the other hand, petroleum-based raw materials do not contain 14C. Therefore, the concentration of the radioactive isotope 14C is measured by accelerator mass spectrometry, and the proportion of plant-based raw material content in the resin composition is calculated. The bio-based carbon concentration can be evaluated by radiocarbon analysis based on the ASTM D6866 method (20-B).

[0026] Biomass-derived sebacic acid contains a large amount of residual inorganic particulate matter. In this invention, we have found that the majority of these residual inorganic particulate matter is metal sulfate salts that are by-products in the manufacturing process of sebacic acid.

[0027] Biomass-derived sebacic acid is produced using plant-derived raw materials such as castor oil. In the production process, a large excess of alkali is added to the raw materials such as castor oil, and the mixture is heated to decompose it. When separating sebacic acid from the decomposed reaction solution, a large amount of sulfuric acid is used to dissipate the alkali metal salts of sebacic acid. As a result, a large amount of metal sulfate salts are produced as a by-product in the process of producing biomass-derived sebacic acid, and although by-product removal treatments are performed, some remain.

[0028] The polyamide resin composition of the present invention has a content of 1000 ppm or less of metal sulfate salts, which are inorganic particulate components. Preferably, it is 500 ppm or less, and more preferably 300 ppm or less.

[0029] When the metal sulfate content exceeds 1000 ppm, a large amount of coarse inorganic particles accumulate in the filtration filter within the melt system during melt spinning, causing clogging. As a result, the pressure in the extruder piping increases, making stable melting difficult. Furthermore, during the fiber manufacturing stage, metal sulfates crystallize and aggregate to form coarse inorganic particles that remain in the fiber. These coarse inorganic particles can cause filament breakage, resulting in filament splitting (fuzzing). This filament breakage also leads to a decrease in strength. In particular, in the case of fine polyamide fibers for clothing with low total and individual filament fineness, the fiber diameter is small (fine), and the proportion of coarse inorganic particle size relative to the fiber diameter is high, making them more susceptible to these effects.

[0030] Therefore, by keeping the content of metal sulfate salts below 1000 ppm, it is possible to suppress the rapid increase in filtration pressure, the generation of fluff, and the decrease in strength during melt spinning, thereby providing high-quality, fine-denier polyamide fibers with good spinning operability. In particular, polyamide resins with a bio-based carbon concentration of 50% by weight or more have a high content of metal sulfate salts, which are inorganic particulate components contained in biomass-derived sebacic acid, making them prone to aggregation and highly susceptible to the influence of coarse inorganic particles.

[0031] The content of metal sulfate salts, which are inorganic particulate components, is determined by dissolving the polyamide resin in a solvent, filtering it through a 2 μm membrane filter, and calculating the content from the amount of ash in the residual inorganic particles remaining on the filter. The metal compounds in these inorganic particles can be analyzed and quantified by methods such as ion chromatography or atomic absorption spectrometry.

[0032] Furthermore, reducing the metal sulfate content to 0 ppm would incur enormous costs for purification and other processes required to completely remove the metal sulfates, making it economically disadvantageous in terms of improving spinning efficiency and yarn quality. Therefore, considering the balance between cost, spinning efficiency, and yarn quality, a lower limit of 5 ppm for metal sulfate content is industrially desirable.

[0033] Furthermore, the metal component of the metal sulfate salt depends on the alkaline component used in the production of sebacic acid. Examples include sodium hydroxide (NaOH) or potassium hydroxide (KOH). While the metal component of metal sulfate salts is often sodium or potassium, it is not limited to these. It is even more preferable that the total content of sodium and potassium salts in the metal sulfate salt is 70% or more of the metal sulfate salt.

[0034] The polyamide resin composition of the present invention preferably has a degree of yellowing YI of 6.0 or less for the pellets. The degree of yellowing YI is a value measured by the method described later. A low YI indicates less discoloration. If the discoloration is high (poor color tone), the applications are limited and it leads to a decrease in quality, so a low YI is preferable. By making the degree of yellowing YI of the pellets 6.0 or less, clear and high-quality fibers that do not affect the color development after dyeing can be obtained, especially in clothing fiber applications. The degree of yellowing YI of the pellets of the polyamide resin composition of the present invention is more preferably 2.0 or less, and even more preferably 0.0 or less. The lower limit of the degree of yellowing YI is about -10.

[0035] The polyamide resin composition of the present invention preferably contains 1.5% by weight or less of low polymer components detected by hot water extraction. More preferably, it contains 1.0% by weight or less. By keeping the amount of low polymer components within this range, the generation of low polymer components during fiber production using the polyamide resin composition is suppressed. This reduces yarn breakage caused by low polymer components (such as spinneret filament contamination), making it possible to produce polyamide fibers with good operability. Furthermore, since spinneret filament contamination is reduced, the periodic cleaning of the spinneret surface, which is performed during long-term continuous production, can be extended.

[0036] The polyamide resin composition of the present invention may be supplemented with known end-cap agents to adjust its molecular weight. Monocarboxylic acids are preferred as end-cap agents. Other examples include acid anhydrides such as phthalic anhydride, monoisocyanates, monoacid halides, monoesters, and monoalcohols.

[0037] There are no particular restrictions on the monocarboxylic acids that can be used as end-capturing agents, as long as they are reactive with an amino group. Examples include aliphatic monocarboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecyl acid, myristic acid, palmitic acid, stearic acid, pivalic acid, and isobutyric acid; alicyclic monocarboxylic acids such as cyclohexanecarboxylic acid; and aromatic monocarboxylic acids such as benzoic acid, toluic acid, α-naphthalenecarboxylic acid, β-naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid, and phenylacetic acid. In the present invention, one or more of these monocarboxylic acids may be used.

[0038] The polyamide resin composition of the present invention may contain other additives depending on the application, as long as they do not impair the effects of the present invention. These additives can be added during the copolymerization of the polyamide or by melt-mixing them with the polyamide resin composition. When melt-mixing, an extruder can be used.

[0039] Furthermore, these additives can also be incorporated by blending master chips containing these additives with chips, or by physically mixing them with pellets of polyamide resin composition, and then subjecting them to molding processes such as spinning, extrusion, or injection molding.

[0040] Examples of such additives include antioxidants and heat stabilizers (hindered phenols, hydroquinones, phosphites and their derivatives, copper halides, iodine compounds, etc.), weathering agents (benzophenones, hindered amines, etc.), mold release agents and lubricants (aliphatic alcohols, aliphatic amides, etc.), pigments (titanium dioxide, carbon black, etc.), dyes (nigrosine, aniline black, etc.), nucleating agents (talc, silica, kaolin, clay, etc.), antistatic agents (polyetheramide antistatic agents, polyether esteramide antistatic agents, etc.), flame retardants (melamine cyanurate, magnesium hydroxide, etc.), fillers (graphite, barium sulfate, magnesium sulfate, calcium carbonate, magnesium carbonate, etc.), and other polymers (other polyamides, polyethylene, polypropylene, polyester, polycarbonate, etc.).

[0041] The polycondensation method of polyamide is not particularly limited in the present invention, but preferred manufacturing methods for obtaining the polyamide resin composition of the present invention are shown. There are generally two methods for polycondensation of polyamides: continuous polymerization and batch polymerization. Production is possible using either method, but the outline of the batch polymerization method for polyamide polycondensation will be shown using polypentamethylene sevacamide as an example.

[0042] An aqueous solution of equimolar salts of sebacic acid and 1,5-diaminopentane is prepared and concentrated by heating in a pressure vessel (concentration step). The water content of the equimolar salt aqueous solution can be adjusted considering the convenience of handling and weighing, but 10-60% is preferred, and 10-50% is more preferred. Concentration can also be performed in a separate apparatus from the polycondensation apparatus to an arbitrary water content, in which case the water content after concentration is preferably 10-30%, and more preferably 10-20%. To the concentrated equimolar aqueous solution of the salt, 1,5-diaminopentane is added in an amount that meets the desired amino-terminal group requirements. While the addition of 1,5-diaminopentane may be done before concentration, it is preferable to add it after concentration to minimize evaporation during concentration.

[0043] The concentrated equimolar aqueous solution is heated in a sealed container until the target pressure is reached (pressurization step). The maximum pressure inside the container is preferably 1.0 MPa or higher, more preferably 1.3 MPa (absolute pressure) or higher, and even more preferably 1.7 MPa or higher. A pressure of 1.0 MPa or higher can reduce the evaporation of 1,5-diaminopentane. There is no particular upper limit, but considering the pressure resistance of the polycondensation apparatus, it is preferably 3.0 MPa or lower, and even more preferably 2.0 MPa or lower.

[0044] While maintaining the above pressure, the container is allowed to evaporate moisture until the internal temperature reaches 240-250°C (pressure reduction step). Then, while continuing heating, the internal pressure of the container is gradually reduced to 0.1 MPa (atmospheric pressure) (pressure release step). The temperature at which pressure release begins is important; if it is 240°C or higher, polycondensation can occur without the internal liquid solidifying during the pressure release step, and if it is 250°C or lower, thermal degradation of the polymer can be suppressed.

[0045] To proceed with polycondensation after the depressurization process, there are two methods: one is to remove condensation water by circulating an inert gas while the internal pressure of the container is at atmospheric pressure (atmospheric pressure polymerization), and the other is to reduce the internal pressure of the container (reduced pressure polymerization). When the internal pressure of the container is reduced, the water in the polymer vaporizes rapidly and foams, causing the polymer to adhere to the can wall, where it is heated and thermally degraded. This thermally degraded material is then mixed back into the polymer liquid, generating microgels. Therefore, atmospheric pressure polymerization is preferred in this invention. Examples of inert gases include helium gas, argon gas, and nitrogen gas, with nitrogen gas being preferred from a cost perspective.

[0046] The reaction time at atmospheric pressure to advance polycondensation to the desired degree of polymerization is preferably 20 to 50 minutes. More preferably, it is 20 to 40 minutes.

[0047] Furthermore, the maximum temperature inside the container for atmospheric pressure polymerization is preferably 240 to 250°C. This range suppresses thermal degradation even during prolonged atmospheric pressure polymerization, reducing polymer discoloration and microgel formation. More preferably, the temperature is 245 to 250°C. Above 240°C, the polymer's melt viscosity does not increase excessively, maintaining good fluidity within the container. Below 250°C, thermal degradation, including polymer discoloration and microgel formation, can be suppressed.

[0048] The preferred polymerization conditions for polyhexamethylene sebakamid, which consists of 1,6-diaminohexane and sebamic acid, are the same as the preferred polycondensation method for polypentamethylene sebakamid described above.

[0049] In the case of polytetramethylene sebakamid, which consists of 1,4-diaminobutane and sebaic acid, the melting point of the polyamide resin composition is high, so the maximum temperature in the container for atmospheric pressure polymerization is preferably 250 to 260°C, and more preferably 255 to 260°C. If the temperature is 250°C or higher, the melt viscosity of the polymer does not increase too much, and good fluidity in the container can be maintained. If the temperature is 260°C or lower, deterioration of the polymer's color can also be suppressed. The polyamide resin composition thus obtained is preferably extruded from the container in a strand shape, cut, and formed into pellets.

[0050] Since metal sulfate salts such as sodium sulfate and potassium sulfate contained in bio-based sebacic acid are water-soluble, performing hot water washing (extraction treatment) before use in yarn production can remove not only low polymer components but also metal sulfate salts. In the present invention, the extraction method for the polyamide resin composition pellets is not particularly limited, but it is carried out by continuous extraction and batch extraction methods.

[0051] As a method for reducing the amount of low polymer components in a polyamide resin composition, Patent Document 1 of the prior art describes a method of extraction in high-temperature hot water at 80°C to 140°C for 4 to 50 hours. However, in this method, because the extraction temperature is high, the polyamide resin composition is greatly affected by thermal degradation, resulting in poor color and a high YI value of the polyamide resin composition. Therefore, in order to avoid the effects of thermal degradation, it is preferable to extract at a temperature below the glass transition point of the polyamide resin.

[0052] Furthermore, the solubility of metal sulfate salts contained in bio-based sebacic acid is temperature-dependent. For example, the amount of sodium sulfate (anhydrous) dissolved in 100g of saturated solution is 48.1g (40°C) and 42.2g (100°C), indicating that it is nearly saturated at 40°C. Similarly, the amount of potassium sulfate (anhydrous) is 12.9g (40°C) and 19.4g (100°C), representing approximately 67% solubility compared to extraction with boiling water. Therefore, depending on the type of polyamide resin, considering thermal degradation, the solubility of metal sulfate salts, and the dissolution of low polymer components, the extraction temperature is preferably 40°C to 80°C, more preferably 40°C to 60°C, and most preferably 40°C to 50°C.

[0053] By extracting at this temperature, the content of metal sulfate salts can be reduced to 1000 ppm or less, and furthermore, the YI value can be reduced to 6.0 or less, and the amount of low polymer components can be reduced to 1.5% by weight or less. As a result, biomass-derived polyamide fibers with excellent spinning operability and quality (color tone and strength) can be obtained.

[0054] When the temperature exceeds 80°C, thermal degradation causes the polyamide resin composition to deteriorate in color, resulting in poor color and reduced quality even after fiberization. If extraction is not performed or if the temperature is below 40°C, the removal of metal sulfates and low polymer components is insufficient, causing an increase in filtration pressure during yarn production. This not only worsens operability but also degrades quality, such as reducing strength.

[0055] The extraction time varies depending on the pellet shape of the polyamide resin composition, the extraction temperature, and the bath ratio. However, short extraction times tend to result in insufficient removal of metal sulfates and low polymer components, while long extraction times tend to worsen the color. Generally, the extraction time is about 24 to 144 hours, preferably about 36 to 108 hours, and most preferably 48 to 72 hours. The bath ratio is preferably 1.0 to 15.0 m 3 / ton, more preferably 4.0~12.0m 3 / ton, most preferably 7-10.5m 3 It is done at a rate of / ton. The bath ratio is the ratio of polymer to hot water.

[0056] The polyamide resin composition (pellets) after the extraction and preparation process contains approximately 2-8% by weight of moisture, so it is preferable to dry it.

[0057] In the present invention, the drying or solid-phase polymerization method for the polyamide resin composition (pellets) includes a batch heating method under reduced pressure of 1.3 kPa or less, or a method of continuously contacting the polyamide resin composition (pellets) with heated nitrogen. When mass-producing polyamide resin compositions (pellets), the latter method, which allows for continuous operation, is advantageous, while the former method is advantageous when producing small quantities of many different products.

[0058] Typically, drying is carried out by holding the polyamide at a temperature range of 80°C to 120°C for about 10 to 30 hours until the moisture content is approximately 0.1% by weight or less. Furthermore, it is possible to increase the molecular weight by solid-phase polymerization of polyamide resin pellets.

[0059] Solid-phase polymerization proceeds by heating the temperature in the range of 120°C to the melting point using the method described above, and it is possible to increase the molecular weight of polyamide resin compositions that have insufficient molecular weight through heating polycondensation.

[0060] The polyamide resin composition of the present invention is in the form of pellets and is preferably used in textile applications, and particularly preferably in textile applications for clothing.

[0061] The fibers obtained from the polyamide resin composition of the present invention are manufactured by known melt spinning. For example, molten polyamide pellets are weighed and transported by a gear pump, discharged from a spinneret, and cooled and solidified to room temperature by passing through a steam injection device located directly below the spinneret and toward the spinneret surface, and a region located downstream of the steam injection device where cooling air is blown from a cooling device. Then, the yarn is lubricated by an oil supply device to concentrate the yarn, entangled by a fluid entanglement nozzle device, and passed through a take-up roller and a stretching roller. At this time, the yarn is stretched according to the ratio of the peripheral speeds of the take-up roller and the stretching roller. Furthermore, the yarn is heat-set by heating the stretching roller and wound up by a winder (winding device). [Examples]

[0062] The present invention will be further described with reference to the following examples, but the present invention is not limited to the descriptions in these examples.

[0063] [Relative viscosity of sulfuric acid ηr] 0.25 g of resin pellets were dissolved in 100 ml of 98 wt% sulfuric acid to a total volume of 1 g, and the flow time (T1) at 25°C was measured using an Ostwald viscometer. Subsequently, the flow time (T2) of 98 wt% sulfuric acid alone was measured. The ratio of T1 to T2, i.e., T1 / T2, was defined as the relative viscosity ηr of the sulfuric acid.

[0064] [Yellowing degree YI] The degree of yellowing of resin pellets was measured using a color computer manufactured by Suga Test Instruments Co., Ltd. The measurement method followed JIS standard K7105 (Test method for the optical properties of plastics).

[0065] [Sulfate metal salt content / Sodium content / Potassium content] Ten g of resin pellets were weighed and transferred to a platinum container, then heated in an electric furnace at 800°C for two hours. The resulting ash was weighed (A), and the metal sulfate content was calculated. Sulfate metal salt content (ppm by weight) = Aμg / 10g. The generated ash was dissolved in 5 mL of concentrated sulfuric acid, and the solution was made up in a 10 mL volumetric flask with concentrated sulfuric acid. The sodium and potassium content in the resin pellets was then calculated using an ICP emission spectrometer (ICPE-9800) in accordance with JIS K0133 (2007).

[0066] [Amount of low polymer component] After crushing the resin pellets, the mixture was sieved through 35-mesh (opening 420 μm) and 115-mesh (opening 125 μm) wire mesh filters. The powder that passed through the 35-mesh filter and remained in the 115-mesh filter was separated. The obtained powder was dried until its moisture content was 0.03% by weight or less, and approximately 3 g was weighed (W1). The weighed powder was extracted in 10 L or more of boiling water for 4 hours. The obtained powder was washed with water, dried until its moisture content was 0.03% by weight or less, and then weighed (W2). The following formula was used to calculate the result from W1 and W2. Amount of low polymer component (wt%)=(W1-W2) / W1×100.

[0067] [Bio-based carbon concentration] The bio-based carbon concentration of the resin pellets was analyzed by radiocarbon analysis according to the ASTM D6866 method.

[0068] [Filtration pressure rise rate ΔP] Resin pellets dried at 105°C for 8 hours under a vacuum of 133 Pa or less were subjected to a filterability test (Fuji Filter Industry Co., Ltd. Melt Spinning Tester CII) to measure the rate of increase in filtration pressure. The filter used was a Watanabe Yoshiichi Manufacturing Co., Ltd. Dynalloy Filter X5 (mesh opening 5 μm, filtration area 4.5 cm²). 2 Filtration was performed using a polymer temperature of 280°C and a flow rate of 4g / min. The difference between the filtration pressure after 1 hour and 2 hours after filter installation was measured and defined as the pressure rise rate ΔP (MPa / hour). The measurement results were categorized as follows, with ◎, ○, and △ indicating pass / fail. ◎: Less than 1.0 MPa / hour. ○: 1.0 MPa / hour or more, and less than 5.0 MPa / hour. △: 5.0 MPa / hour or more, and less than 10.0 MPa / hour. ×: 10.0 MPa / hour or more.

[0069] [Strength (fiber properties)] A. Fineness A fiber sample was placed in a measuring device with a circumference of 1.125 m, rotated 500 times to create a loop-shaped skein, dried in a hot air dryer (105 ± 2°C, 60 minutes), the skein mass was measured using a balance, and the fineness (dtex) was calculated from the value multiplied by the official moisture content.

[0070] B. Strength Fiber samples were measured according to JIS L1013 (2010) for tensile strength and elongation. The test conditions were a constant-speed tensioning machine, a gripping distance of 50 cm, and a tensile speed of 50 cm / min. If the strength at break was less than the maximum strength, the maximum strength and the elongation at that point were measured. The strength was calculated using the following formula. Strength = Strength at break (cN) / Fineness (dtex) The measurement results were categorized as follows, with ◎, ○, and △ indicating a passing grade. ◎: 4.75cN / dtex or more, 5.0cN / dtex or less. ○: 4.5 cN / dtex or higher, and less than 4.75 cN / dtex. △: 4.25 cN / dtex or higher, and less than 4.5 cN / dtex. ×: Less than 4.25 cN.

[0071] [Spinning nozzle stains] The spinning nozzle was removed, and five experienced fiber evaluation inspectors performed a visual sensory evaluation of the foreign matter accumulated around the ejection hole using a microscope. The results were calculated by taking the average of each inspector's evaluation score and rounding to the nearest whole number. An average score of 5 was given as ◎, 4 as ○, 3 as △, and 1-2 as ×. 5 points: Excellent 4 points: Slightly above average 3 points: Average 2 points: Slightly inferior 1 point: Inferior ◎, ○, and △ were considered to meet the quality standards.

[0072] [Color Tone (Textile Packaging)] The obtained fiber packages were subjected to visual sensory evaluation by five experienced inspectors in a location with natural light on the north side. The results were calculated by taking the average of each inspector's evaluation score and rounding to the nearest whole number. An average score of 5 was given as ◎, 4 as ○, 3 as △, and 1-2 as ×. 5 points: Excellent 4 points: Slightly above average 3 points: Average 2 points: Slightly inferior 1 point: Inferior ◎, ○, and △ were considered to meet the quality standards.

[0073] (Reference Example 1) (Preparation of a 40% by weight aqueous solution of 1,5-diaminopentane sebacate) An aqueous solution of 1,5-diaminopentane (manufactured by Tokyo Chemical Industry Co., Ltd.) diluted with deionized water was stirred while immersed in an ice bath. Small amounts of sebacic acid (manufactured by Kirk Co., Ltd.), which has an equimolar amount of radioactive carbon (C14) content of 70% or more, were added to the solution. Near the neutralization point, the solution was heated in a 40°C water bath to bring the internal temperature down to 33°C, and a 40% by weight aqueous solution of 1,5-diaminopentane / sebacic acid equimolar salt was prepared. A 40% by weight aqueous solution of 1,6-diaminohexane / sebacic acid equimolar salt and a 40% by weight aqueous solution of 1,4-diaminobutane / sebacic acid equimolar salt were prepared using the same method.

[0074] (Reference Example 2) (Preparation of a 40% by weight aqueous solution of 1,6-diaminohexane sebacate) An aqueous solution of 1,6-diaminohexane (manufactured by Tokyo Chemical Industry Co., Ltd.) diluted with deionized water was stirred, and sebacic acid (manufactured by Kirk Co., Ltd.), which has an equimolar amount of radioactive carbon (C14) content of 70% or more, was added in small amounts. Near the neutralization point, the solution was heated in a 40°C water bath to bring the internal temperature down to 33°C, and a 40 wt% aqueous solution of 1,6-diaminohexane-sebacic acid equimolar salt was prepared. Using the same method, a 40 wt% aqueous solution of 1,5-diaminopentane-sebacic acid equimolar salt and a 40 wt% aqueous solution of 1,4-diaminobutane-sebacic acid equimolar salt were prepared.

[0075] (Reference Example 3) (Preparation of a 40% by weight aqueous solution of 1,4-diaminobutane sebacate) An aqueous solution of 1,4-diaminobutane (manufactured by Tokyo Chemical Industry Co., Ltd.) diluted with deionized water was stirred, and sebacic acid (manufactured by Kirk Co., Ltd.), which has an equimolar amount of radioactive carbon (C14) content of 70% or more, was added in small amounts. Near the neutralization point, the solution was heated in a 40°C water bath to bring the internal temperature down to 33°C, and a 40 wt% aqueous solution of 1,6-diaminohexane / sebacic acid equimolar salt was prepared. A 40 wt% aqueous solution of 1,5-diaminopentane / sebacic acid equimolar salt and a 40 wt% aqueous solution of 1,4-diaminobutane / sebacic acid equimolar salt were prepared using the same method.

[0076] (Example 1) Three kilograms of a 40% by weight aqueous solution of 1,5-diaminopentane sebaciate obtained in Reference Example 1 were placed in a jacketed autoclave. After thoroughly purging the container with nitrogen, the solution was heated and concentrated until the water content reached 15% by weight, while maintaining a container temperature of 200°C and a container pressure of 0.2 MPa (gauge pressure) (concentration step). The concentration of the aqueous solution in the container was determined from the amount of distillate. After concentration, the solution was transferred to an autoclave equipped with a stirrer and a heat transfer medium jacket. The heat transfer medium was heated to 290°C, and the pressure was increased while stirring at 30 rpm until the container pressure (gauge pressure) reached 1.7 MPa (pressure increase step). After this, the container pressure (gauge pressure) was maintained at 1.7 MPa until the container temperature reached 245°C (pressure control step). Subsequently, the pressure was released to atmospheric pressure over 50 minutes (pressure release step). While adjusting the heating temperature so that the internal temperature at the end of atmospheric pressure polymerization was between 245°C and 250°C, nitrogen gas was circulated at a rate of 0.5 L / min (50 L / min) per kg of polymer and blown for 30 minutes to increase the degree of polymerization (atmospheric pressure process). Subsequently, a nitrogen pressure of 0.5 MPa (absolute pressure) was applied to the container, and the polyamide resin composition obtained by polycondensation was extruded into strands with a diameter of approximately 3 mm, cut to a length of approximately 4 mm, and 1 kg of pellets was obtained (dispensing process).

[0077] The obtained pellets were placed in a batch-type extraction tank, and 10 times the weight of the pellets in ion-exchanged water (extraction water) adjusted to 50±1℃ was added, followed by extraction for 72 hours. After treatment, the pellets were thoroughly rinsed with ion-exchanged water and dehydrated using a centrifuge (extraction process). The results for the obtained polyamide 510 resin composition (pellets) are shown in Table 1.

[0078] The obtained polyamide 510 resin composition (pellets) was dried to a moisture content of 0.10% by weight or less, and then reeled into fibers as follows.

[0079] At a spinning temperature of 280°C, the fibers were melt-extruded at a rate of 28 g / min from a spinneret with 24 extrusion holes (hole diameter 0.2 mm, hole elongation 0.7 mm). After melt-extrusion, the fibers were cooled, lubricated, and entangled before being taken up by a Godet roller at 1900 m / min. Subsequently, they were stretched to 1.9 times their original length, heat-set at 155°C, and wound at a winding speed of 3500 m / min to obtain nylon 510 fibers and fiber packages with a total fineness of 22 decitex and 24 filaments. The results are shown in Tables 1 and 2.

[0080] (Comparative Example 1) Polymerization and yarn production were carried out in the same manner as in Example 1, except that the extraction step was omitted, to obtain nylon 510 fibers. The results are shown in Table 1.

[0081] (Examples 2-12) Polymerization, extraction, and yarn production were carried out in the same manner as in Example 1, except that the extraction water temperature and extraction time were changed as shown in Table 2, to obtain nylon 510 fibers. The results are shown in Table 2.

[0082] (Example 13) 3 kg of a 40 wt% aqueous solution of 1,6-diaminohexanesebacic acid obtained in Reference Example 2 was placed in a jacketed autoclave. After thoroughly purging the container with nitrogen, the autoclave was heated and concentrated until the water content of the aqueous solution reached 15 wt% while maintaining a container temperature of 200°C and a container pressure of 0.2 MPa (gauge pressure) (concentration step). The concentration of the aqueous solution in the container was determined from the amount of distillate. After concentration, the solution was transferred to an autoclave equipped with a stirrer and a heat transfer medium jacket. The heat transfer medium was heated to 290°C, and the pressure was increased while stirring at 30 rpm until the container pressure (gauge pressure) reached 1.7 MPa (pressure increase step). After this, the container pressure (gauge pressure) was maintained at 1.7 MPa and the container temperature was maintained at 245°C (pressure control step). Subsequently, the pressure was released to atmospheric pressure over 50 minutes (pressure release step). While adjusting the heating temperature so that the internal temperature at the end of atmospheric pressure polymerization was between 245°C and 250°C, nitrogen gas was circulated at a rate of 0.5 L / min (50 L / min) per kg of polymer and blown for 30 minutes to increase the degree of polymerization (atmospheric pressure process). Subsequently, a nitrogen pressure of 0.5 MPa (absolute pressure) was applied to the container, and the polyamide resin composition obtained by polycondensation was extruded into strands with a diameter of approximately 3 mm, cut to a length of approximately 4 mm, and 1 kg of pellets was obtained (dispensing process).

[0083] The obtained pellets were extracted and spun into yarn in the same manner as in Example 1 to obtain nylon 610 fibers. The results are shown in Tables 1 and 2.

[0084] (Comparative Example 2) Polymerization and yarn production were carried out in the same manner as in Example 6, except that the extraction step was omitted, to obtain nylon 610 fibers. The results are shown in Table 1.

[0085] (Example 14) 3 kg of a 40 wt% aqueous solution of 1,4-diaminobutane sebaciate obtained in Reference Example 3 was placed in a jacketed autoclave. After thoroughly purging the container with nitrogen, the solution was heated and concentrated until the water content in the solution reached 5 wt% while maintaining a container temperature of 150°C and a container pressure of 0.2 MPa (gauge pressure) (concentration step). The concentration of the aqueous solution in the container was determined from the amount of distillate. After concentration, the solution was transferred to an autoclave equipped with a stirrer and a heat transfer medium jacket. The heat transfer medium was heated to 290°C, and the pressure was increased while stirring at 30 rpm until the container pressure (gauge pressure) reached 1.0 MPa (pressure boosting step). After this, the container pressure (gauge pressure) was maintained at 1.0 MPa and the container temperature was maintained at 255°C (pressure control step). Subsequently, the pressure was released to atmospheric pressure over 50 minutes (pressure release step). While adjusting the heating temperature so that the internal temperature at the end of atmospheric pressure polymerization was between 255°C and 260°C, nitrogen gas was circulated at a rate of 0.5 L / min (50 L / min) per kg of polymer, and the mixture was blown for 30 minutes to increase the degree of polymerization (atmospheric pressure process). Subsequently, a nitrogen pressure of 0.5 MPa (absolute pressure) was applied to the container, and the polyamide resin composition obtained by polycondensation was extruded into strands with a diameter of approximately 3 mm, cut into lengths of approximately 4 mm, and 1 kg of pellets was obtained (dispensing process).

[0086] The obtained pellets were extracted and spun into yarn in the same manner as in Example 1 to obtain nylon 410 fibers. The results are shown in Tables 1 and 2.

[0087] (Comparative Example 3) Polymerization and yarn production were carried out in the same manner as in Example 14, except that the extraction step was omitted, to obtain nylon 410 fibers. The results are shown in Table 1.

[0088] [Table 1]

[0089] [Table 2]

Claims

1. A polyamide resin composition comprising a diamine component and sebacic acid, wherein the content of metal sulfate salts, which are inorganic particulate components, is 1000 ppm or less, and the bio-based carbon concentration is 50% or more.

2. The polyamide resin composition according to claim 1, wherein the metal component of the metal sulfate salt is sodium or potassium.

3. The polyamide resin composition according to claim 1 or claim 2, wherein the degree of yellowing YI of the pellets of the polyamide resin composition is 6.0 or less.

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