CN113736249A

CN113736249A - Polyamide 56 resin, fiber, preparation method and application thereof

Info

Publication number: CN113736249A
Application number: CN202010467386.2A
Authority: CN
Inventors: 孙朝续; 陈万钟; 高祥; 刘修才
Original assignee: Cathay R&D Center Co Ltd; CIBT America Inc
Current assignee: Cathay R&D Center Co Ltd; CIBT America Inc
Priority date: 2020-05-28
Filing date: 2020-05-28
Publication date: 2021-12-03

Abstract

The invention provides polyamide 56 resin, a fiber, a preparation method and an application thereof, wherein the preparation method of the polyamide 56 resin comprises the step of polymerizing a monomer to prepare the polyamide 56 resin, and the polyamide 56 resin contains titanium dioxide, wherein the titanium dioxide is added in the polymerization reaction process. According to the preparation method of the polyamide 56 resin, the problems of filament breakage, poor dyeing property and the like in the subsequent spinning process can be effectively avoided; meanwhile, the preparation method is simple and easy to operate, and the production cost is low.

Description

Polyamide 56 resin, fiber, preparation method and application thereof

Technical Field

The invention relates to polyamide, in particular to polyamide 56 resin, fiber, and preparation methods and applications thereof.

Background

Polyamide fiber is one of synthetic fibers which are put into industrial production at the earliest time in the world, and plays a very important role in the field of synthetic fibers. Polyamide fibers are of various types, and currently, polyamide 6 and polyamide 66 are the most widely used and industrially produced. The main applications relate to: socks, lace underwear, corset, sports underwear, wedding dress, casual jacket, sports wear, wind-rain coat, outdoor tent, sleeping bag, climbing bag and the like; and industrial yarn is widely used in such fields as cord, transmission belt, hose, rope, fishing net, tire, parachute, etc.

The polyamide fiber is divided into a bright fiber and a dull fiber according to whether the delustering agent is contained or not, the fabric prepared from the bright fiber has obvious surface gloss and strong surface wax texture and is difficult to be applied to casual clothes and high-grade clothes with higher requirements, and the fabric prepared from the dull fiber has the advantages of soft gloss, natural effect approaching, soft hand feeling, bright color, good drapability, strong shielding performance and the like, and is more and more pursued by consumers.

Titanium dioxide (TiO)₂) Is widely used as a matting materialIs widely applied to the field of chemical fiber matting fibers. At present, the main production method of the extinction fiber mainly adopts an on-line extinction master batch adding technology. In the method, firstly, the extinction master batch is added in the spinning process, a spinning factory is required to be equipped with a master batch adding device, and the production investment is large; secondly, the adding proportion of the master batch needs to be strictly controlled in the master batch adding process, if the mixing proportion is improper or the mixing is not uniform, the poor compatibility of the extinction master batch and the matrix resin is easily caused, and the problems of broken monofilaments, broken filaments, low strength, dyeing color difference and the like are easily generated in the spinning process.

The invention patent application (publication number CN105986327A) discloses a polyamide 56 fiber and a manufacturing method thereof, wherein the spinning step comprises the following steps: a plurality of polyamide 6 matte resin particles were provided and melt-kneaded with the polyamide 56 resin particles subjected to the viscosity and moisture adjustment step, and spun at 275 ℃ to 285 ℃ to obtain matte 56 fibers. In the material, firstly, the melting point of polyamide 6 is about 220 ℃, the melting point of polyamide 56 is about 256 ℃, and the difference between the melting points of the polyamide 6 and the polyamide 56 is large, so that the improper control of spinning processing conditions can cause phase separation, thereby causing the conditions of melt viscosity reduction and fiber strength reduction; secondly, in order to prepare polyamide 56 fibers with a high titanium dioxide content, polyamide 6 matting resin particles with a content of more than 10 weight percent need to be added into polyamide 56 resin particles, which causes poor compatibility and causes problems of increase of broken filaments and ends, reduction of fiber strength, uneven dyeing, reduction of M rate and the like in the spinning process.

The patent application of the invention (with the publication number of CN 110054891A) discloses a delustering polyamide 56 master batch, a delustering fiber and a preparation method thereof, wherein the delustering polyamide 56 master batch is prepared firstly, and then the delustering polyamide 56 master batch and the polyamide 56 are blended and spun to prepare the delustering fiber, so that the production investment is large. And the blending addition extinction master batch spinning method is adopted, the master batches are required to be added uniformly, otherwise, the extinction master batches are easy to be compatible with the matrix spinning material, and the problems of filament breakage, dyeing color difference, low M rate and the like are caused.

Disclosure of Invention

The main object of the present invention is to provide a polyamide 56 resin comprising titanium dioxide, wherein the content of titanium dioxide is 0.2 to 5.0 wt%, and the dispersed particle size of 98% or more of titanium dioxide is 0.2 to 0.6 μm.

The invention further provides a preparation method of the polyamide 56 resin, which comprises the step of polymerizing the monomers to prepare the polyamide 56 resin, wherein the polyamide 56 resin contains titanium dioxide, and the titanium dioxide is added in the polymerization reaction process.

An embodiment of the present invention further provides a polyamide 56 fiber prepared by melt spinning the above polyamide 56 resin or directly spinning a melt generated during the preparation of the polyamide 56 resin.

An embodiment of the present invention further provides a method for preparing the polyamide 56 fiber, including the following steps:

(a) heating the polyamide 56 resin to a molten state to obtain a polyamide 56 melt;

(b) feeding the polyamide 56 melt into a spinning manifold, injecting the melt into a spinning assembly, and extruding nascent fibers from spinneret orifices;

(c) cooling, oiling, stretching and winding the nascent fiber to obtain polyamide 56 pre-oriented yarn;

(d) and carrying out hot stretching treatment on the polyamide 56 pre-oriented yarn through a first roller, then cooling and shaping, and then carrying out false twister, second roller, netmaker, oiling treatment and winding treatment to obtain the polyamide 56 fiber.

An embodiment of the present invention further provides a use of the above polyamide 56 fiber in a knitted or woven fabric.

According to the preparation method of the polyamide 56 resin, the problems of yarn breakage, poor dyeing property and the like in the subsequent spinning process can be effectively avoided; meanwhile, the preparation method is simple and easy to operate, and the production cost is low.

Detailed Description

Exemplary embodiments that embody features and advantages of the invention are described in detail below. It is to be understood that the invention is capable of other and different embodiments and its several details are capable of modification without departing from the scope of the invention, and that the description is intended to be illustrative in nature and not to be construed as limiting the invention.

One embodiment of the present invention provides a method for preparing polyamide 56 resin, comprising polymerizing monomers to obtain polyamide 56 resin, wherein the polyamide 56 resin contains titanium dioxide, and the titanium dioxide is added during the polymerization.

According to the method provided by the embodiment of the invention, titanium dioxide is added in the polymerization process of polyamide 56 for in-situ polymerization, so that the titanium dioxide can be uniformly distributed in the polyamide 56 resin, and the problems of yarn breakage, poor dyeing property and the like in the subsequent spinning process can be effectively avoided; meanwhile, the preparation method is simple and easy to operate, and the production cost is low.

In the method of one embodiment of the present invention, TiO is directly added in the polymerization process₂The method has relatively simple operation, convenient control, no need of additional master batch adding device, reduced production investment, and TiO addition during polymerization₂Can make TIO₂Longer mixing time with resin, so that TiO₂The dispersion is more uniform in matrix resin, the broken monofilaments and broken filaments in the subsequent spinning process are fewer, the fiber strength is high, and the dyeability is good.

In one embodiment, the particle size of the titanium dioxide powder added in the polymerization of polyamide 56 may be 0.15 to 0.5. mu.m, further 0.15 to 0.4. mu.m, further 0.15 to 0.3. mu.m, such as 0.18. mu.m, 0.20. mu.m, 0.22. mu.m, 0.23. mu.m, 0.25. mu.m, 0.27. mu.m, 0.28. mu.m.

The titanium dioxide may be added to the polymerization system of polyamide 56 in the form of particles, or may be added to the polymerization system of polyamide 56 in the form of a slurry of titanium dioxide.

In one embodiment, the amount of titanium dioxide added is 0.2 to 5.0 wt%, and more preferably 0.2 to 3.0 wt% based on the total weight of the polyamide 56 resin.

In one embodiment, the raw materials for producing the polyamide 56 resin include at least 1, 5-pentanediamine and adipic acid; alternatively, 1, 5-pentanediamine and adipic acid are used as monomers to polymerize polyamide 56.

In one embodiment, the 1, 5-pentanediamine is prepared from bio-based materials by fermentation or enzymatic conversion.

In the method for preparing polyamide 56 resin according to an embodiment of the present invention, the raw material for production is a non-petroleum-based material, such as a bio-based material, which does not cause significant pollution and is environmentally friendly.

In one embodiment, a method of preparing a polyamide 56 resin comprises:

(1) preparing a polyamide 56 salt solution;

(2) polymerizing polyamide 56 salt solution serving as a raw material to prepare polyamide 56 melt;

(3) and filtering the polyamide 56 melt through a melt filter, and finally pelletizing and drying to obtain the polyamide 56 resin.

In one embodiment, titanium dioxide may be added at any one or more of the stages of step (1) and step (2).

In one embodiment, step (1) comprises: under the condition of nitrogen, 1, 5-pentanediamine, adipic acid and water are uniformly mixed to prepare a polyamide 56 salt solution.

In one embodiment, the molar ratio of 1, 5-pentanediamine to adipic acid may be (1-1.08): 1, for example, 1.02:1, 1.04:1, 1.05:1, 1.06:1, and the like.

In one embodiment, step (2) comprises: heating the polyamide 56 salt solution to raise the pressure in the reaction system to 0.3-2.4 MPa (gauge pressure), exhausting and maintaining the pressure for 0.2-2.5 h, then reducing the pressure to reduce the pressure in the reaction system to 0-0.3 MPa (gauge pressure), and then vacuumizing to the vacuum degree of-0.001-0.08 MPa (gauge pressure) to obtain the polyamide 56 melt.

In one embodiment, the temperature of the reaction system at the end of the pressure holding in step (2) is 230 to 265 ℃, for example, 235 ℃, 240 ℃, 245 ℃, 250 ℃, 255 ℃, and the like.

In one embodiment, the pressure maintaining time in step (2) is 0.5-2 h, and further 0.5-1.5 h, such as 0.8h, 1h, and 1.2 h.

In one embodiment, the temperature of the reaction system after the pressure reduction in step (2) is completed is 240 to 275 ℃, for example, 245 ℃, 250 ℃, 255 ℃, 260 ℃, 265 ℃, 270 ℃ and the like.

In one embodiment, the temperature after the vacuum-pumping in step (2) is 250 to 285 ℃, for example, 255 ℃, 260 ℃, 265 ℃, 270 ℃, 275 ℃, 280 ℃, and the like.

In one embodiment, the time for maintaining the vacuum degree after the vacuum pumping in the step (2) is 10-50 min; further 15-45 min.

In one embodiment, the second additive may be added to the reaction system, and may be added at any one or more stages of the step (1) and the step (2). The second additive may or may not be added simultaneously with the titanium dioxide.

In one embodiment, the second additive may include one or more of a flame retardant, an antioxidant, a capping agent, an ultraviolet absorber, an infrared absorber, a crystallization nucleating agent, a fluorescent whitening agent, and an antistatic agent.

In one embodiment, the second additive is added in an amount of 0 to 1% by weight, for example, 0.05%, 0.1%, 0.2%, 0.4%, 0.5%, 0.6%, 0.8% by weight, based on the total weight of the raw materials for producing the polyamide 56 resin.

In one embodiment, after the drying treatment in step (3), the water content of the resin is 300 to 1000ppm, more preferably 300 to 800ppm, and still more preferably 600 to 800 ppm.

In one embodiment, the temperature of the drying treatment in step (3) may be 80 to 130 ℃, and further may be 100 to 110 ℃, for example, 90 ℃, 95 ℃, 98 ℃, 102 ℃, 104 ℃, 105 ℃, 106 ℃, 108 ℃, 115 ℃, 120 ℃, 125 ℃ and the like.

In one embodiment, the time of the drying treatment in step (3) may be 10 to 30 hours, and further may be 15 to 25 hours, such as 12 hours, 16 hours, 18 hours, 20 hours, 22 hours, 24 hours, 28 hours, and the like.

In one embodiment, step (3) is performed by filtering with a melt filter before pelletizing to remove TiO from the polymerization process₂The large-size particles generated by the agglomeration can ensure that the particle diameter of the titanium dioxide in the polyamide 56 resin is small and the distribution is narrow, and the titanium dioxide can enterThe uniformity of the polyamide 56 melt is improved in one step, and further the phenomena of filament breakage and more broken filaments generated in the stretching process due to overlarge particle size and the influence on the mechanical property and dyeing property of the fiber caused by the filament breakage and the broken filaments are avoided, so that the number of broken filaments in the subsequent spinning process is small, and the dyeing property is improved.

In one embodiment, the dispersion particle size of titanium dioxide in the delustered polyamide 56 resin is 0.2 to 1.0 μm, more preferably, 98% or more of the dispersion particle size of titanium dioxide particles is 0.2 to 0.6 μm, and further more preferably, 95% or more of the dispersion particle size of titanium dioxide particles is 0.2 to 0.35 μm, as measured by melt filter filtration.

In one embodiment, the melt filter has a mesh size of 5-15 um.

In the method for preparing polyamide 56 resin according to an embodiment of the present invention, TiO is used₂The delustered polyamide 56 resin is prepared by carrying out in-situ polymerization by strictly controlling TiO₂Particle size and distribution of the particles to avoid or remove TiO₂The agglomerated particles reduce the particle size distribution range and improve the spinning performance.

One embodiment of the present invention provides a polyamide 56 resin, which can be produced by the above-described method.

One embodiment of the present invention provides a polyamide 56 resin, which has a relative viscosity of 2.3 to 3.0, and further 2.5 to 2.8; an oligomer content of 1.5 wt% or less, further 1 wt% or less, further 0.8 wt% or less, for example, 0.3 to 1.0 wt%, 0.3 to 0.8 wt%, or the like; the water content can be 300-1000 ppm, further can be 300-800 ppm, further can be 600-800 ppm; the number average molecular weight is 15000 to 42000, and further 18000 to 35000; the molecular weight distribution is 1.2 to 2.0, and further 1.4 to 1.8. The oligomer of the present invention has a polymerization degree of 5 or less.

The polyamide 56 resin according to one embodiment of the present invention has a low oligomer content, a narrow molecular weight distribution, and a moderate viscosity.

In one embodiment, the relative viscosity of the polyamide 56 resin may be 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, and the like.

In one embodiment, the polyamide 56 resin may have a water content of 350ppm, 550ppm, 650ppm, 700ppm, 750ppm, 850ppm, 900ppm, or the like.

In one embodiment, the number average molecular weight of the polyamide 56 resin may be 16000, 20000, 22000, 25000, 28000, 30000, 32000, 34000, 38000, 40000, and the like.

In one embodiment, the polyamide 56 resin may have a molecular weight distribution of 1.3, 1.5, 1.6, 1.7, 1.9, and the like.

In one embodiment, the polyamide 56 resin oligomer content may be 0.3%, 0.6%, 1.0%. The polymerization degree of the oligomer is below 10, and if the content of the oligomer in the resin is too high, the oligomer is separated out and condensed below a spinneret plate in the spinning process, and the separation is too much, so that the spinning is influenced, and broken filaments are generated in the spinning process. And reduces the service time of the spinning assembly.

In one embodiment, the polyamide 56 resin comprises a titanium dioxide matting agent.

In one embodiment, the polyamide 56 resin may be a semi-dull polyamide 56 resin, a dull polyamide 56 resin, or a full dull polyamide 56 resin.

In one embodiment, the polyamide 56 resin is a semi-dull polyamide 56 resin having a titanium dioxide content of 0.2 to 0.4 wt%, and further 0.25 to 0.35 wt%, such as 0.3 wt%.

In one embodiment, the polyamide 56 resin is a full-dull polyamide 56 resin, and the titanium dioxide content is 1.2 to 2.0 wt%, and further 1.4 to 1.8 wt%, such as 1.5 wt%, 1.6 wt%, and 1.7 wt%.

In one embodiment, the polyamide 56 resin is an ultra-dull polyamide 56 resin, and the content of titanium dioxide is 2.5 to 5.0 wt%, and further 3.0 to 4.5 wt%, such as 2.8 wt%, 3.2 wt%, 3.5 wt%, 4.0 wt%, 4.2 wt%, 4.4 wt%, and 4.8 wt%.

In one embodiment, the dispersed particle size of titanium dioxide in the polyamide 56 resin is 0.2 to 1.0. mu.m, the particle distribution ratio of the dispersed particle size of titanium dioxide is 0.2 to 0.6. mu.m is 98% or more, and the ratio of the dispersed particle size of titanium dioxide is 0.2 to 0.6. mu.m is 98.5% or more; further, the proportion of particles having a dispersed particle diameter of titanium dioxide of 0.2 to 0.35 μm is 95% or more, and the proportion of particles having a dispersed particle diameter of 0.2 to 0.35 μm is 96% or more; wherein the above description of the percentage of titanium dioxide refers to the percentage of the number of titanium dioxide particles.

One embodiment of the present invention provides a polyamide 56 fiber which can be obtained by melt spinning the polyamide 56 resin.

In one embodiment, the polyamide 56 fibers may be semi-dull polyamide 56 fibers, full dull polyamide 56 fibers; wherein, the semi-dull polyamide 56 fiber, the dull polyamide 56 fiber and the full dull polyamide 56 fiber can be respectively prepared by melt spinning of semi-dull polyamide 56 resin, dull polyamide 56 resin and full dull polyamide 56 resin.

In one embodiment, the polyamide 56 fiber includes undrawn yarn (UDY), Fully Drawn Yarn (FDY), pre-oriented yarn (POY), Highly Oriented Yarn (HOY), Fully Oriented Yarn (FOY), textured yarn (DTY), continuous bulk textured yarn (BCF), monofilament, staple fiber, and industrial yarn, preferably pre-oriented yarn (POY) and textured yarn (DTY). Textured yarns are also known as drawn false-twist yarns or draw textured yarns.

The polyamide 56 fiber of one embodiment of the present invention has the advantages of high strength, low-temperature dyeability, hygroscopicity, flexibility, wear resistance, high elasticity, etc., and has a wide development prospect in the field of civil yarns and industrial yarns.

In one embodiment, the monofilament fineness of the polyamide 56 fiber may be 0.5 to 5.0dtex, further 0.8 to 4.0dtex, further 1.2 to 3.0dtex, further 1.2 to 2.0dtex, such as 1.0, 1.5, 1.8, 2.5, 3.5, 4.5dtex, etc.

In one embodiment, the breaking strength of the polyamide 56 fiber can be 3.3 to 5.5cN/dtex, further 3.5 to 4.8cN/dtex, further 3.7 to 4.5cN/dtex, further 3.9 to 4.2 cN/dtex.

In one embodiment, the coefficient of variation in breaking strength of the polyamide 56 fiber is 5.0% or less, further 3.0% or less, further 2.5% or less, further 2.0% or less.

In one embodiment, the initial modulus of the polyamide 56 fiber can be 15 to 35cN/dtex, further 22 to 33cN/dtex, further 24 to 30cN/dtex, further 26 to 28 cN/dtex.

In one embodiment, the boiling water shrinkage of the polyamide 56 fiber may be 7% or less, more preferably 6.8% or less, still more preferably 6.5% or less, and still more preferably 6.0% or less.

In one embodiment, the moisture regain of the polyamide 56 fiber may be 4.0% or more, more preferably 4.5% or more, still more preferably 5.0% or more, and still more preferably 5.5% or more.

In one embodiment, the crimp shrinkage of the polyamide 56 fiber may be 35 to 60%, more preferably 40 to 58%, and still more preferably 45 to 55%.

In one embodiment, the crimp stability of the polyamide 56 fiber may be 38 to 58%, more preferably 40 to 56%, still more preferably 48 to 54%, for example 45%, 50%, 52%.

In one embodiment, the polyamide 56 fiber has a dyeing uniformity (gray card) of grade 3.5 or more, further grade 4.0 or more, further grade 4.5 or more, and further grade 5.0 or more.

In one embodiment, the M-ratio of the polyamide 56 fibers is 92% or more, more preferably 94% or more, still more preferably 96% or more, and still more preferably 98% or more.

In one embodiment, the soaping fastness of the polyamide 56 fiber: the color fastness can be more than or equal to 3.5 grade, further more than or equal to 4.0 grade, further more than or equal to 4.5 grade, further more than or equal to 5.0 grade; the staining fastness may be at least 3.5 level, further at least 4.0 level, further at least 4.5 level, further at least 5.0 level.

An embodiment of the present invention provides a method for preparing the polyamide 56 fiber, including the steps of:

(a) heating polyamide 56 resin to a molten state to form a polyamide 56 melt;

(b) conveying the polyamide 56 melt into a spinning box body through a melt pipeline, accurately metering by a metering pump, injecting into a spinning assembly, and extruding at high pressure from a spinneret orifice to obtain nascent fiber;

(c) and cooling, oiling, stretching and winding the extruded nascent fiber to obtain the polyamide 56 pre-oriented yarn.

(d) The polyamide 56 pre-oriented yarn is fed to a first roller through a yarn guide, passes through a twist stopper, is subjected to hot drawing in a first hot box, is cooled and shaped by a cooling plate, passes through a false twister, a second roller and a network device, is oiled and is wound to obtain the polyamide 56 elastic yarn.

In one embodiment, the heating in step (a) is performed by a screw, wherein the temperature in one zone may be 245-265 ℃, and further 250-260 ℃; the temperature of the second zone can be 260-280 ℃, and further can be 265-275 ℃; the temperature of the three zones can be 275-285 ℃, and further can be 278-283 ℃; the temperature of the four zones can be 280-290 ℃.

In one embodiment, the temperature of the spinning beam in the step (b) may be 278 to 290 ℃, and further 282 to 285 ℃; the pressure of the spinning pack may be 13 to 22MPa, and further 15 to 18 MPa.

In one embodiment, the cooling of step (c) comprises side-blown cooling and circular-blown cooling, preferably circular-blown cooling; the wind speed can be 0.3-0.8 m/s, and further can be 0.45-0.6 m/s; the air temperature can be 18-23 ℃; the degree of rheumatism may be 50 to 85%, and further 55 to 70%.

In one embodiment, the applying of step (c) is a nozzle tip application; the oiling rate can be 0.4-0.6 wt%, and further can be 0.45-0.55 wt%; the oiling height can be 80-150 cm, further can be 90-130 cm, and further can be 95-110 cm.

In one embodiment, the winding speed during the winding process in step (c) may be 4000 to 5000m/min, further 4200 to 4800m/min, and further 4300 to 4500 m/min; the overfeed rate may be 10 to 100m/min, and further 20 to 80 m/min.

In one embodiment, the thermal stretching ratio in step (d) may be 1.1 to 1.4, and further may be 1.15 to 1.35; the temperature of the hot stretching may be 160 to 210 ℃, further 170 to 205 ℃, and further 180 to 195 ℃.

In one embodiment, the speed ratio D/Y of the false twister in the step (D) may be 1.3 to 2.2, and further may be 1.5 to 2.0; the pressure of the compressed air in the network device can be 0.3-1.5 MPa, further 0.4-1.2 MPa, and further 0.5-1.0 MPa.

In one embodiment, the applying of step (d) is a nozzle tip applying; the oiling rate can be 2.2-2.8 wt%, and further can be 2.3-2.6 wt%.

In one embodiment, the winding speed in the winding step (d) may be 300 to 800m/min, and further may be 400 to 700 m/min; the winding overfeed speed during winding is 1 to 8%, further 1.5 to 6%, and further 2 to 5%.

In one embodiment of the invention, the raw material for producing the polyamide 56 fiber can be prepared by a biological method, is a green material, does not depend on petroleum resources, does not cause serious pollution to the environment, and can reduce the emission of carbon dioxide and reduce the generation of greenhouse effect.

The polyamide 56 fiber provided by the embodiment of the invention can be prepared by adopting conventional spinning equipment of polyamide 6 and polyamide 66, the spinning equipment is not required to be modified, and the preparation rate can be improved by optimizing the quality of the polyamide 56 fiber resin and the spinning process.

The polyamide 56 fiber provided by the embodiment of the invention has good mechanical properties, dimensional stability, hygroscopicity and dyeing properties, and has a good extinction effect when applied to knitted or woven fabrics.

An embodiment of the invention provides an application of the polyamide 56 fiber in knitted or woven fabrics. The light transmittance of the polyamide 56 fabric can be less than or equal to 50%, further less than or equal to 48%, further less than or equal to 35%, and further less than or equal to 30%.

In one embodiment, the polyamide 56 fiber has high strength, softness, moisture absorption, fluffiness (crimp stability), easy dyeing and delustering properties, and is more suitable for knitting and civil apparel. The application for the knitted and tatted fabric comprises the fields of underwear, shirts, suits, yoga coats, down coats, outdoor jackets, socks, cases, curtains, shoe materials, embroidery threads, trademarks, sofa cloth, tools, sportswear, elastic bands and the like without limitation.

The fabric prepared from the polyamide 56 fiber provided by the embodiment of the invention has good extinction performance and the same TiO content₂The content extinction effect is better than that of the polyamide 6 fiber and the polyamide 66 fiber, and the polyamide 56 fabric with the same extinction effect is prepared by adding TiO₂The content is lower, and the production cost can be reduced.

The light transmittance of the semi-dull polyamide 56 fabric provided by the embodiment of the invention can be less than or equal to 48%, the light transmittance of the full-dull polyamide 56 fabric can be less than or equal to 33%, and the light transmittance of the super-dull polyamide 56 fabric can be less than or equal to 25%.

Hereinafter, the polyamide 56 resin, the polyamide 56 fiber, and the production thereof according to one embodiment of the present invention will be described in detail with reference to specific examples. Wherein, unless otherwise specified, all the raw materials used are commercially available, and the details of the relevant tests involved are as follows; the parameters according to the present invention were measured as follows.

1) Fineness number:

measured according to GB/T14343.

2) Breaking strength, modulus: the determination of the breaking strength can refer to a GB/T14344-2008 chemical fiber tensile property test method; applying a pretension of 0.05 +/-0.005 cN/dtex, a holding distance of 500mm and a stretching speed of 500 mm/min; modulus is the breaking strength corresponding to 1% elongation at break x 100.

3) The determination method of the moisture regain comprises the following steps: putting the washed fiber in a loose state into an oven for drying, and then putting the dried fiber sample in standard atmosphere specified in GB/T6529 for humidifying to balance; and (4) measuring the moisture regain, wherein the moisture regain measuring method is executed according to GB/T6503, the drying temperature of the oven is 105 ℃, and drying is carried out.

4) Shrinkage in boiling water:

the pretension was measured according to GB/6505 at 0.05. + -. 0.005 cN/dtex.

5) Dyeing evenness (grey card)/grade:

and (3) keeping the temperature at 98 ℃ for 30min according to the FZ/T50008 nylon filament dyeing uniformity test method, and judging the dyeing uniformity.

6) Water content of resin:

and (4) measuring by a Karl Fischer water content titrator.

7) Crimp shrinkage, crimp stability: GB/T6506-.

8) Soaping fastness:

measured according to GB/T3921.1-1997.

9) Relative viscosity of resin: concentrated sulfuric acid method by Ubbelohde viscometer: accurately weighing 0.25 +/-0.0002 g of dried polyamide resin slices, and adding 50mL of concentrated sulfuric acid (96 wt%) for dissolution; measuring and recording the flowing time t0 of concentrated sulfuric acid and the flowing time t of the polyamide sample solution in a constant-temperature water bath at 25 ℃;

viscosity number calculation formula: relative viscosity t/t₀；

t-solution flow time;

t₀-solvent flow time.

10) Number average molecular weight and molecular weight distribution of resin: gel Permeation Chromatography (GPC).

11) Titanium dioxide dispersion particle size: the dispersion particle size of titanium dioxide was measured and counted from a transmission electron micrograph of a polyamide resin chip.

12) M rate: the M ratio (the dyeing uniformity is equal to or more than 4.5 fiber weight/total weight of all dyed fibers) x 100%.

13) Extinction property: the fibers prepared in the examples and the comparative examples are weaved by the same air jet loom, rinsed by an open width soaping machine and dyed by a liquid flow dyeing machine to prepare fabrics with uniform specification, and the extinction performance grades are visually evaluated and averaged by setting a specific detection group (10 people), namely, the surface extinction performance of the fabrics are compared under the conditions of halogen lamps simulating sunlight and the temperature of 25 ℃, and the extinction performance evaluation grades are divided into grades 1, 2, 3, 4 and 5, which shows that the extinction performance is respectively from low to very high.

14) Light transmittance: and (3) measuring by an ultraviolet-visible spectrophotometer, wherein the scanning wavelength is 300-800nm, and the light transmittance of the fabric refers to the light transmittance at the wavelength of 550 nm.

15) Fiber yield: the yield (weight of finished fiber prepared/total charged resin) x 100%.

16) And (3) testing the content of oligomer in the resin:

drying a polyamide sample in a forced air oven at 130 ℃ for 7 hours, then placing the polyamide sample into an aluminum-plastic bag, sealing the opening, then placing the polyamide sample into a dryer for cooling, then accurately weighing 2g of the polyamide sample, placing the polyamide sample into a 250mL round-bottom flask, adding 100mL of water, heating and refluxing for 24 hours at 100 ℃ by using a heating sleeve, taking out the polyamide sample, washing the polyamide sample with pure water for three times, drying the polyamide sample in the forced air oven at 130 ℃ for 7 hours, then transferring the polyamide sample into a pre-weighed aluminum-plastic bag, sealing the opening, then placing the polyamide sample into the dryer for cooling, weighing the total weight of the aluminum-plastic bag and the polyamide sample, subtracting the weight of the aluminum-plastic bag to obtain the weight of the polyamide sample after water boiling, and calculating the content of oligomer by comparing the weight difference before and after water boiling of the polyamide sample. Each sample was tested in duplicate.

17) Testing the content of titanium dioxide in the resin: calcination method, 10g of the sample was put into a crucible, calcined in a muffle furnace at 480 ℃ for 10 hours, and the weight of the residue in the crucible was weighed.

18) Coefficient of Variation (CV) test of breaking strength: reference is made to GB/T14344-. The titanium dioxide is uniformly distributed in the fibers, so that different fibers are simultaneously broken in the stretching process, and the corresponding breaking strengths are consistent during breaking, which shows that the coefficient of variation is small.

19) The number of broken filaments: and manually counting the yarn breakage times in the process of preparing the polyamide fiber by the nascent fiber.

Example 1

Preparation of Polyamide 56 resin

(1) Under the condition of nitrogen, 1, 5-pentanediamine, hexanedioic acid and water are uniformly mixed to prepare a polyamide 56 salt solution; wherein the molar ratio of the 1, 5-pentanediamine to the hexanedioic acid is 1.05: 1.

(2) Adding titanium dioxide with the particle size of 0.2 mu m into polyamide 56 salt solution, heating the salt solution system to ensure that the pressure in the reaction system is increased to 2.4MPa, exhausting and maintaining the pressure for 1.2h, then reducing the pressure in the reaction system to gauge pressure of 0MPa, then vacuumizing to ensure that the vacuum degree is-0.04 MPa, and maintaining the vacuum degree for 35min to obtain polyamide 56 melt; wherein the adding amount of the titanium dioxide is 0.27 wt% of the resin prepared without adding the titanium dioxide under the same condition, the temperature of the reaction system is 260 ℃ when the pressure maintaining is finished, the temperature of the reaction system is 275 ℃ after the pressure reducing is finished, and the temperature of the reaction system is 280 ℃ after the vacuum pumping is finished.

(3) Filtering the polyamide 56 melt through a melt filter, wherein the mesh number of a filter screen in the melt filter is 10 mu m, and then cutting into particles and drying to obtain polyamide 56 resin; wherein the drying temperature is 110 ℃, and the drying time is 20 h.

Preparation of Polyamide 56 fibers

(a) Heating the prepared polyamide 56 resin to a molten state to form a polyamide 56 melt; the heating was carried out using screws with a temperature in the first zone of 253 deg.C, a temperature in the second zone of 266 deg.C, a temperature in the third zone of 278 deg.C and a temperature in the fourth zone of 288 deg.C.

(b) Conveying the polyamide 56 melt into a spinning box body through a melt pipeline, accurately metering by a metering pump, injecting into a spinning assembly, and extruding from a spinneret orifice at high pressure; wherein the temperature of the spinning manifold is 285 ℃, and the pressure of the spinning assembly is 16.2 MPa.

(c) Cooling, oiling, stretching and winding the extruded nascent fiber to obtain polyamide 56 pre-oriented yarn; wherein, the cooling adopts circular blowing, the wind speed is 0.48m/s, the wind temperature is 20 ℃, and the rheumatism degree is 80%; oiling is performed by an oil nozzle, the oiling rate is 0.5 wt%, and the oiling height is 110 cm; the winding speed during winding forming is 4300m/min, and the overfeed speed is 60 m/min.

(d) The polyamide 56 pre-oriented yarn is fed to a first roller through a yarn guide, is subjected to hot drawing in a first hot box through a twist stopper, is cooled and shaped by adopting a cooling plate, and is oiled and wound through a false twister, a second roller, a network device and an oil nozzle to obtain polyamide 56 elastic yarn;

wherein the hot stretching multiple is 1.3, and the hot stretching temperature is 185 ℃; the speed ratio D/Y of the false twister is 1.8; the pressure of compressed air in the network device is 0.8 MPa; oiling is performed by an oil nozzle, and the oiling rate is 2.5 wt%; the winding speed during winding was 600m/min, and the winding overfeed speed during winding was 2.5%.

Example 2

Preparation of Polyamide 56 resin

Polyamide 56 resin was prepared using essentially the same raw materials and process as in example 1, except that: the amount of titanium dioxide added in step (2) was 0.34 wt%.

Preparation of Polyamide 56 fibers

The polyamide 56 resin obtained above was used as a raw material for spinning, and the specific spinning process was the same as in example 1.

Example 3

Preparation of Polyamide 56 resin

Essentially the same starting materials as in example 1 were used, except that: the vacuum degree of the step (2) is-0.07 MPa, the maintaining time is 10min, and the adding amount of the titanium dioxide in the step (2) is 0.35 wt%.

Preparation of Polyamide 56 fibers

Example 4

Preparation of Polyamide 56 resin

Polyamide 56 resin was prepared using essentially the same raw materials and process as in example 1, except that: the amount of titanium dioxide added in step (2) was 1.23 wt%, and the mesh size of the filter mesh in the melt filter in step (3) was 5 μm.

Preparation of Polyamide 56 fibers

Example 5

Preparation of Polyamide 56 resin

Polyamide 56 resin was prepared using essentially the same raw materials and process as in example 1, except that: the amount of titanium dioxide added in step (2) was 1.56 wt%, and the mesh size of the filter mesh in the melt filter in step (3) was 15 μm.

Preparation of Polyamide 56 fibers

Example 6

Preparation of Polyamide 56 resin

Polyamide 56 resin was prepared using essentially the same raw materials and process as in example 1, except that: the amount of titanium dioxide added in step (2) was 1.84% by weight.

Preparation of Polyamide 56 fibers

Example 7

Preparation of Polyamide 56 resin

Polyamide 56 resin was prepared using essentially the same raw materials and process as in example 1, except that: the amount of titanium dioxide added in step (2) was 2.56% by weight.

Preparation of Polyamide 56 fibers

Example 8

Preparation of Polyamide 56 resin

Polyamide 56 resin was prepared using essentially the same raw materials and process as in example 1, except that: the amount of titanium dioxide added in step (2) was 3.05 wt%.

Preparation of Polyamide 56 fibers

Example 9

Preparation of Polyamide 56 resin

Polyamide 56 resin was prepared using essentially the same raw materials and process as in example 1, except that: the amount of titanium dioxide added in step (2) was 4.05 wt%.

Preparation of Polyamide 56 fibers

Example 10

Preparation of Polyamide 56 resin

Polyamide 56 resin was prepared using essentially the same raw materials and process as in example 1, except that: in the step (2), the addition amount of the titanium dioxide is 0.34 wt%, the vacuum degree is vacuumized to-0.06 MPa, and the temperature of the reaction system after the vacuum pumping is 285 ℃.

Preparation of Polyamide 56 fibers

Example 11

Preparation of Polyamide 56 resin

Polyamide 56 resin was prepared using essentially the same starting materials and procedures as in example 10, except that: the amount of titanium dioxide added in step (2) was 1.54% by weight.

Preparation of Polyamide 56 fibers

Example 12

Preparation of Polyamide 56 resin

Polyamide 56 resin was prepared using essentially the same starting materials and procedures as in example 10, except that: the amount of titanium dioxide added in step (2) was 2.53 wt%.

Preparation of Polyamide 56 fibers

Example 13

Preparation of Polyamide 56 fibers

The polyamide 56 resin prepared in the example 10 is used as a raw material for spinning, and the specific spinning process is basically the same as that of the example 1: the only difference is that: the spinning assembly contains a 10 μm nonwoven filter screen.

Example 14

Preparation of Polyamide 56 fibers

The polyamide 56 resin prepared in the example 11 is used as a raw material for spinning, and the specific spinning process is basically the same as that of the example 1: the only difference is that: the spinning assembly contains a non-woven fabric filter screen with the thickness of 15 mu m.

Example 15

Preparation of Polyamide 56 fibers

The polyamide 56 resin prepared in the example 11 is used as a raw material for spinning, and the specific spinning process is basically the same as that of the example 1: the only difference is that: the spinning assembly contains a 20 μm nonwoven filter screen.

Comparative example 1

Preparation of Polyamide 56 resin

Polyamide 56 resin was prepared using essentially the same raw materials and process as in example 2, except that: and (4) filtering without a melt filter in the step (3), and directly pelletizing to obtain the polyamide 56 resin.

Preparation of Polyamide 56 fibers

Comparative example 2

Preparation of Polyamide 56 resin

Polyamide 56 resin was prepared using essentially the same starting materials and procedures as in example 5, except that: and (4) filtering without a melt filter in the step (3), and directly pelletizing to obtain the polyamide 56 resin.

Preparation of Polyamide 56 fibers

Comparative example 3

Preparation of Polyamide 56 resin

Polyamide 56 resin was prepared using essentially the same starting materials and procedures as in example 7, except that: and (4) filtering without a melt filter in the step (3), and directly pelletizing to obtain the polyamide 56 resin.

Preparation of Polyamide 56 fibers

Comparative example 4

Preparation of Polyamide 6 fibers

Polyamide 6 resin (viscosity 2.7, molecular weight distribution 1.59, oligomer content 0.61%, water content 612ppm) and 0.33 wt% titanium dioxide (particle size 0.2um) were mixed as a spinning material, and spun by the same spinning process as in example 1 to obtain polyamide 6 fiber; the content of titanium dioxide is based on the mass of the polyamide 6 resin.

Comparative example 5

Preparation of Polyamide 66 fibers

Polyamide 66 resin (viscosity 2.68, molecular weight distribution 1.61, oligomer content 0.62%, water content 605ppm) and 0.32 wt% titanium dioxide (particle size 0.2um) were mixed as a spinning material, and spun by the same spinning process as in example 1 to obtain polyamide 66 fiber; the content of titanium dioxide is based on the mass of the polyamide 66 resin.

Comparative example 6

Preparation of Polyamide 56 fibers

Polyamide 56 resin (viscosity 2.68, molecular weight distribution 1.61, oligomer content 0.61%, water content 607ppm) and 0.26 wt% titanium dioxide (particle size 0.2um) were mixed as a spinning material, and spun by the same spinning process as in example 1 to obtain polyamide 56 fiber; the content of titanium dioxide is based on the mass of the polyamide 56 resin.

Comparative example 7

Preparation of Polyamide 56 resin

Polyamide 56 resin was prepared using essentially the same starting materials and procedures as in example 5, except that: the mesh number of the filter screens in the melt filter in the step (3) is 20 mu m.

Preparation of Polyamide 56 fibers

The polyamide 56 resins prepared in examples 1 to 12 and comparative examples 1 to 3 were subjected to the relevant property tests, and the results are shown in Table 1.

TABLE 1 Properties of Polyamide 56 resin of examples and comparative examples

The polyamide fibers prepared in examples 1 to 15 and comparative examples 1 to 7 were subjected to the relevant property tests, and the results are shown in tables 2 and 3.

TABLE 2 Polyamide fibre Properties of the examples and comparative examples

TABLE 3 Polyamide fibre Properties of the examples and comparative examples

Unless otherwise defined, all terms used herein have the meanings commonly understood by those skilled in the art.

The described embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of the present invention, and those skilled in the art may make various other substitutions, alterations, and modifications within the scope of the present invention, and thus, the present invention is not limited to the above-described embodiments but only by the claims.

Claims

1. Polyamide 56 resin comprises titanium dioxide, wherein the content of the titanium dioxide is 0.2-5.0 wt%, and the dispersion particle size of more than 98% of the titanium dioxide is 0.2-0.6 mu m.

2. The polyamide 56 resin according to claim 1, wherein 95% or more of the titanium dioxide has a dispersed particle diameter of 0.2 to 0.35. mu.m.

3. The polyamide 56 resin of claim 1, wherein the titanium dioxide is present in an amount of 0.2 to 0.4 wt%, 1.2 to 2.0 wt%, or 2.5 to 5.0 wt%.

4. The polyamide 56 resin according to claim 1, wherein the polyamide 56 resin has a relative viscosity of 2.3 to 3.0; and/or the polyamide 56 resin has a water content of 300-1000 ppm; and/or the molecular weight distribution of the polyamide 56 resin is 1.2-2.0; and/or the oligomer content of the polyamide 56 resin is less than 1.5 wt%.

5. A preparation method of polyamide 56 resin comprises the step of polymerizing monomers to obtain the polyamide 56 resin, wherein the polyamide 56 resin contains titanium dioxide, and the titanium dioxide is added in the polymerization process.

6. The method of claim 5, wherein the monomers comprise 1, 5-pentanediamine and adipic acid, and the polymerization process comprises the steps of:

(1) preparing a polyamide 56 salt solution;

(2) polymerizing the polyamide 56 salt solution serving as a raw material to prepare a polyamide 56 melt;

adding the titanium dioxide in the step (1) and/or the step (2).

7. The method of claim 6, wherein the step (2) comprises: heating the polyamide 56 salt solution to enable the pressure of a polyamide 56 salt solution reaction system to be increased to 0.3-2.4 MPa, exhausting and maintaining the pressure for 0.2-2.5 h, then reducing the pressure to enable the pressure in the reaction system to be reduced to 0-0.3 MPa, and then vacuumizing to enable the vacuum degree in the reaction system to be-0.001-0.08 MPa.

8. The process according to claim 7, wherein the temperature of the reaction system at the end of the pressure holding process is 230 to 265 ℃; and/or the presence of a gas in the gas,

after the pressure reduction process is finished, the temperature of the reaction system is 240-275 ℃; and/or the presence of a gas in the gas,

after vacuumizing, the temperature of the reaction system is 250-285 ℃;

and/or maintaining the vacuum degree for 10-50 min after vacuumizing.

9. The method of claim 6, comprising filtering, pelletizing and drying the melt of polyamide 56 to obtain the polyamide 56 resin.

10. A polyamide 56 fiber obtained by melt spinning a polyamide 56 resin obtained by the method of any one of claims 5 to 9 or a polyamide 56 resin obtained by the method of any one of claims 1 to 4, or directly melt spinning a polyamide 56 obtained by the method of any one of claims 5 to 8.

11. The polyamide 56 fiber according to claim 10, wherein the fiber number per filament is 0.5 to 5.0 dtex; and/or the breaking strength is 3.3-5.5 cN/dtex; and/or the initial modulus is 15-35 cN/dtex; and/or the boiling water shrinkage is less than or equal to 7 percent; and/or the moisture regain is more than or equal to 4.0 percent; and/or the crimping shrinkage rate is 35-60%, and the crimping stability is 38-58%; and/or the dyeing uniformity is more than or equal to 3.5 grade; and/or the M rate is more than or equal to 92 percent, and the color fastness is more than or equal to 3.5 grade; and/or the staining fastness is more than or equal to 3.5 grade.

12. The polyamide 56 fiber of claim 11, comprising one or more of undrawn yarn, fully drawn yarn, pre-oriented yarn, highly oriented yarn, fully oriented yarn, textured yarn, continuous textured yarn, staple fiber, monofilament, and industrial yarn, further preferably pre-oriented yarn and textured yarn.

13. A method for preparing a polyamide 56 fiber according to any one of claims 10 to 12, comprising the steps of:

14. The method according to claim 13, wherein in the step (a), the heating is performed by using a screw, and the temperature of a first zone is 245-265 ℃; the temperature of the second zone is 260-280 ℃; the temperature of the three zones is 275-285 ℃; the temperature of the fourth zone is 280-290 ℃; and/or the presence of a gas in the gas,

in the step (b), the temperature of the spinning manifold is 278-290 ℃, and the pressure of the spinning assembly is 13-22 MPa.

15. The method according to claim 13, wherein in the step (c), the cooling treatment adopts side-blowing cooling or circular-blowing cooling, the wind temperature is 18-23 ℃, and the wind humidity is 50-85%; and/or the oiling treatment is performed by using an oil nozzle, and the oiling rate is 0.4-0.6 wt%; and/or the winding speed of the winding treatment is 4200-5000 m/min, and the overfeed speed is 10-100 m/min.

16. The method according to claim 13, wherein in the step (d), the multiple of the thermal stretching treatment is 1.1 to 1.4, and the temperature of the thermal stretching treatment is 160 to 210 ℃; the speed ratio D/Y of the false twister is 1.3-2.2; the pressure of compressed air in the network device is 0.3-1.5 MPa; the oiling treatment is performed by using an oil nozzle, and the oiling rate is 2.2-2.8 wt%; the winding speed of the winding treatment is 300-800 m/min, and the winding overfeed speed during winding is 1-8%.

17. Use of a polyamide 56 fiber according to any of claims 10 to 12 or a polyamide 56 fiber obtained by a process according to any of claims 13 to 16 in a knitted or woven fabric.