A low-melting-point flame-retardant polyester core fiber, its preparation method and application

Abstract

This invention discloses a low-melting-point flame-retardant polyester core-sheath fiber, its preparation method, and its applications. The low-melting-point flame-retardant polyester core-sheath fiber comprises a sheath layer and a core layer; the sheath layer comprises low-melting-point polyester and zero-dimensional nanoparticles dispersed in the low-melting-point polyester; the core layer comprises conventional melting-point polyester, a phosphorus-containing non-reactive flame retardant dispersed in the conventional melting-point polyester, and modified two-dimensional nanosheets. This invention introduces zero-dimensional nanoparticles into the sheath layer of the low-melting-point flame-retardant polyester core-sheath fiber and introduces modified two-dimensional nanosheets with a high aspect ratio into the core layer as an interface reinforcing agent, resulting in a low-melting-point flame-retardant polyester core-sheath fiber with excellent mechanical properties and flame-retardant effects, greatly expanding its application fields.

Description

Technical Field

[0001] This invention belongs to the field of fiber technology, specifically relating to a low-melting-point flame-retardant polyester core fiber, its preparation method, and its application. Background Technology

[0002] Low-melting-point polyester fiber with a core-sheath structure is a novel fiber material; the core layer is conventional polyester, and the sheath layer is low-melting-point polyester. Due to the presence of low-melting-point polyester in the sheath layer, low-melting-point polyester core-sheath fibers possess advantages such as low-temperature bonding ability, strong adhesion, non-toxicity, and no pollution, and are considered "green adhesives," widely used in the automotive industry, rail transportation, building decoration, medical and health care, and home textiles. However, polyester fiber is a flammable material, posing certain safety hazards, and flame-retardant properties have become a technical bottleneck limiting its safe use.

[0003] There are several reports on the preparation of low-melting-point flame-retardant polyester core-sheath fibers. Korean Patent KR20070059064 discloses a low-melting-point flame-retardant polyester core-sheath fiber with improved flame-retardant properties through copolymerization by introducing a third monomer. Specifically, a hypophosphite derivative is introduced into the polyester molecular chain via copolymerization to improve the flame-retardant properties of the core layer polyester, but the sheath layer is not treated with flame retardancy. This results in a core-sheath structure low-melting-point flame-retardant polyester fiber with a sheath melting point of 110-190℃ and a core melting point of 220-260℃. Korean Patent KR20160039738 discloses a low-melting-point flame-retardant polyester core-sheath fiber with simultaneous copolymerization flame-retardant modification of both the sheath and core layers. Its sheath melting point is 110-158℃, the core melting point is 230-280℃, the oxygen index can reach 36%, and it achieves a UL94 V1 rating with no dripping.

[0004] Patent CN201710018844.2 discloses a method for preparing low-melting-point flame-retardant polyester core-sheath fibers with a flame-retardant core layer using 2-carboxyethylphenyl hypophosphite as the third monomer. However, without flame-retardant treatment of the sheath layer, the prepared low-melting-point flame-retardant polyester fiber with a sheath-core structure has a melting point of 100-170℃ and an oxygen index greater than 28%. Although there are methods for preparing low-melting-point flame-retardant polyester core-sheath fibers, the following limitations still exist: (1) Under existing technical conditions, using only 2-carboxyethylphenyl hypophosphite derivatives as flame-retardant comonomers results in low flame-retardant efficiency of the obtained flame-retardant fiber after copolymerization and spinning; (2) Under existing technical conditions, the interfacial bonding ability between the sheath layer and the core layer is not controlled, resulting in relatively poor mechanical properties; (3) Under existing technical conditions, the combination of flame retardants and additives is not carried out, failing to achieve synergistic flame retardancy. Therefore, providing a polyester core-sheath fiber with high flame-retardant efficiency and good mechanical properties is an urgent problem to be solved. Summary of the Invention

[0005] The main objective of this invention is to provide a low-melting-point flame-retardant polyester core fiber, its preparation method, and its application, so as to overcome the problems of low flame-retardant efficiency and relatively poor mechanical properties of the existing low-melting-point flame-retardant polyester core fiber.

[0006] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0007] This invention provides a low-melting-point flame-retardant polyester core-sheath fiber, which includes a sheath layer and a core layer;

[0008] The skin layer comprises a low-melting-point polyester and zero-dimensional nanoparticles dispersed in the low-melting-point polyester. The molecular structure of the low-melting-point polyester includes polyester segments and phosphorus-containing flame-retardant segments. The phosphorus-containing flame-retardant segments are derived from 2-carboxyethylphenyl hypophosphite and [(6-oxo-6H-dibenzo[C,E][1,2]oxophosphoric acid-6-yl)methyl]succinic acid.

[0009] The core layer comprises a conventional melting point polyester, a phosphorus-containing non-reactive flame retardant dispersed in the conventional melting point polyester, and modified two-dimensional nanosheets. The phosphorus-containing non-reactive flame retardant comprises any one or more combinations of phosphate ester flame retardants and phosphorus-phenanthrene flame retardants.

[0010] This invention also provides a method for preparing the aforementioned low-melting-point flame-retardant polyester core-sheath fiber, comprising:

[0011] Low-melting-point polyester monomers, phosphorus-containing reactive flame retardants, and zero-dimensional nanoparticles are mixed, copolymerized, and then fed into an extruder through a pipeline for extrusion granulation to obtain a skin-layer polyester material.

[0012] Conventional melting point polyester, phosphorus-containing non-reactive flame retardant, and modified two-dimensional nanosheets are mixed, melted, extruded, and granulated to obtain core layer polyester material;

[0013] Furthermore, the sheath polyester material and the core polyester material are subjected to melt spinning treatment to obtain low-melting-point flame-retardant polyester sheath-core fiber.

[0014] This invention also provides the use of the aforementioned low-melting-point flame-retardant polyester core fiber in the automotive industry, rail transportation, building decoration, medical and health care, or home textile fields.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] (1) This invention introduces zero-dimensional nanoparticles into the sheath of low-melting-point flame-retardant polyester core fiber to adjust the melt viscosity and melt strength of the polyester, giving it good anti-dripping properties and enhancing the flame-retardant effect of the condensed phase; two phosphorus-containing flame-retardant segments (2-carboxyethylphenyl hypophosphite and [(6-oxo-6H-dibenzo[C,E][1,2]oxophosphoric acid-6-yl)methyl]succinic acid) are introduced into the low-melting-point flame-retardant polyester to enhance the flame-retardant effect;

[0017] (2) In this invention, modified two-dimensional nanosheets with a high aspect ratio are introduced into the core layer of low-melting-point flame-retardant polyester core fiber as an interface reinforcing agent. The modified two-dimensional nanosheets are surface modified with melamine amide, which increases the interlayer spacing and makes it easier to disperse evenly in the polyester matrix, ensuring good spinnability. On the other hand, the layered nanostructure can migrate to the surface during combustion, playing a better barrier role, thereby blocking the heat and combustible gas exchange between the outer carbon and the inner resin, and playing a role in enhancing flame retardancy.

[0018] (3) This invention regulates the composition and surface microstructure of the core and skin layers, and the polarity of the copolymer flame retardant in the skin layer is greater than that of the polyester itself, which is beneficial to interfacial adhesion. The modified two-dimensional nanosheets in the core layer are radially oriented during the spinning process and are partially present at the core-skin interface, increasing the interface roughness. The multi-component synergistic enhancement of interfacial bonding ability is achieved. The flame retardant in the core layer mainly acts in the gas phase while the flame retardant in the skin layer mainly acts in the condensed phase. The synergy of the two can enhance the flame retardant efficiency of the core-skin structure. Detailed Implementation

[0019] In view of the deficiencies of the prior art, the inventors of this case, through long-term research and extensive practice, have proposed the technical solution of this invention. The technical solution of this invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0020] Specifically, as one aspect of the technical solution of the present invention, a low-melting-point flame-retardant polyester core-sheath fiber includes a sheath layer and a core layer.

[0021] The skin layer comprises a low-melting-point polyester and zero-dimensional nanoparticles dispersed in the low-melting-point polyester. The molecular structure of the low-melting-point polyester includes polyester segments and phosphorus-containing flame-retardant segments. The phosphorus-containing flame-retardant segments are derived from 2-carboxyethylphenyl hypophosphite and [(6-oxo-6H-dibenzo[C,E][1,2]oxophosphoric acid-6-yl)methyl]succinic acid.

[0022] The core layer comprises a conventional melting point polyester, a phosphorus-containing non-reactive flame retardant dispersed in the conventional melting point polyester, and modified two-dimensional nanosheets. The phosphorus-containing non-reactive flame retardant comprises any one or more combinations of phosphate ester flame retardants and phosphorus-phenanthrene flame retardants.

[0023] In some preferred embodiments, the melting point of the low-melting-point polyester is lower than that of the conventional melting-point polyester.

[0024] In some preferred embodiments, the skin comprises the following components by weight: 100 parts low-melting-point polyester and 0.1 to 3 parts zero-dimensional nanoparticles.

[0025] In some preferred embodiments, the mass ratio of low-melting-point polyester to zero-dimensional nanoparticles in the skin layer is 100:(0.5-2).

[0026] Furthermore, the mass ratio of low-melting-point polyester to zero-dimensional nanoparticles in the skin layer is 100:(1-1.5).

[0027] In some preferred embodiments, the sheath comprises 10 to 50 wt% of the total mass of the low-melting-point flame-retardant polyester core fiber.

[0028] In some preferred embodiments, the intrinsic viscosity of the low-melting-point polyester is 0.54 to 0.68 dL / g.

[0029] Furthermore, the intrinsic viscosity of the low-melting-point polyester is 0.58–0.66 dL / g.

[0030] Furthermore, the intrinsic viscosity of the low-melting-point polyester is 0.60–0.64 dL / g.

[0031] In some preferred embodiments, the melting point of the low-melting-point polyester is 85°C to 145°C.

[0032] In some preferred embodiments, the polyester segments include terephthalic acid segments, isophthalic acid segments, ethylene glycol segments, and diethylene glycol segments.

[0033] Further, the molar ratio of the terephthalic acid segment, isophthalic acid segment, ethylene glycol segment and diethylene glycol segment is 1:(0.2-0.5):(1.8-2.5):(0.2-0.4).

[0034] In some preferred embodiments, the mass ratio of the low-melting-point polyester to the phosphorus-containing flame-retardant segments in the low-melting-point polyester is 100:(3-10).

[0035] Furthermore, the mass ratio of the low-melting-point polyester to the phosphorus-containing flame-retardant segment in the low-melting-point polyester is 100:(5-7).

[0036] In some preferred embodiments, the zero-dimensional nanoparticles include any one or more combinations of nano-silica and nano-carbon black, but are not limited thereto.

[0037] In some preferred embodiments, the core layer comprises the following components by weight: 100 parts conventional melting point polyester, 8-20 parts phosphorus-containing non-reactive flame retardant, and 0.1-3 parts modified two-dimensional nanosheets.

[0038] In some preferred embodiments, the mass ratio of conventional melting point polyester to phosphorus-containing non-reactive flame retardant in the core layer is 100:(10-18).

[0039] Furthermore, the mass ratio of conventional melting point polyester to phosphorus-containing non-reactive flame retardant in the core layer is 100:(13-16).

[0040] In some preferred embodiments, the mass ratio of conventional melting point polyester to modified two-dimensional nanosheets in the core layer is 100:(0.5-2).

[0041] Furthermore, the mass ratio of conventional melting point polyester to modified two-dimensional nanosheets in the core layer is 100:(1-1.5).

[0042] In some preferred embodiments, the molecular structure of the conventional melting point polyester includes terephthalic acid segments and ethylene glycol segments.

[0043] In some preferred embodiments, the conventional melting point polyester includes, but is not limited to, polyethylene terephthalate (PET).

[0044] In some preferred embodiments, the melting point of the conventional melting point polyester is 235°C to 265°C.

[0045] In some preferred embodiments, the intrinsic viscosity of the conventional melting point polyester is 0.65 to 0.85 dL / g.

[0046] Furthermore, the intrinsic viscosity of the conventional melting point polyester is 0.68–0.80 dL / g.

[0047] Furthermore, the intrinsic viscosity of the conventional melting point polyester is 0.70–0.75 dL / g.

[0048] In some preferred embodiments, the phosphate ester flame retardant comprises a compound having the structure shown in formula (I) or formula (II):

[0049]

[0050] In some preferred embodiments, the phosphorus-phenanthrene flame retardant comprises a compound having the structure shown in formula (III):

[0051]

[0052] In some preferred embodiments, the phosphorus-containing flame-retardant segment is composed of (2-Carboxyethylphenyl hypophosphite), ([(6-oxo-6H-dibenzo[C,E][1,2]oxophosphazenecyclo-6-yl)methyl]succinic acid)(DDP) is involved in the copolymerization to form this.

[0053] In some preferred embodiments, the modified two-dimensional nanosheets are obtained by surface modification of two-dimensional nanosheets using melamine amide.

[0054] Furthermore, the two-dimensional nanosheets include any one or more combinations of nanoscale montmorillonite, attapulgite, illite, and sepiolite, and are not limited thereto.

[0055] In some preferred embodiments, the method for preparing the modified two-dimensional nanosheets includes: replacing calcium ions in the two-dimensional nanosheets with sodium ions, then blending the two-dimensional nanosheets containing sodium ions with melamine amide, and further adding phosphoric acid and reacting with ultrasonic stirring to obtain surface-functionalized high aspect ratio two-dimensional nanosheets, i.e., modified two-dimensional nanosheets.

[0056] In some more specific embodiments, the method for preparing the modified two-dimensional nanosheets includes:

[0057] Step 1: Disperse the two-dimensional nanosheets in a saturated sodium chloride solution to allow for sufficient ion exchange. Sodium ions can displace calcium ions from between the layers, resulting in two-dimensional nanosheets with sodium ions as the exchangeable cations between the layers. The exchange temperature is 25–85℃, and the exchange time is 1–24 h.

[0058] Step 2: The two-dimensional nanosheets (with sodium ions as the cations) obtained by displacement are redispersed in deionized water, melamine amide is added, and the mixture is stirred at high speed until fully mixed; the stirring temperature is 65-85℃, and the displacement time is 1-6 hours.

[0059] Step 3: Add excess phosphoric acid to the mixture prepared in Step 2, and stir with ultrasound at a constant temperature for several hours; wherein, the molar ratio of two-dimensional nanosheets (cation is sodium ion), melamine amide and phosphoric acid is 1:(0.1~0.3):(0.2~1.0), the reaction temperature is 30~90℃, and the reaction time is 1~12h;

[0060] Step 4: Let the reaction solution stand for a certain period of time, remove the supernatant to obtain the precipitate, wash it repeatedly with deionized water and filter it under reduced pressure to obtain melamine amide surface modified high aspect ratio two-dimensional nanosheets, i.e.: modified two-dimensional nanosheets; the standing time is 8-16 hours.

[0061] In some preferred embodiments, the aspect ratio of the modified two-dimensional nanosheet is 5 to 16.

[0062] In some preferred embodiments, the material of the conventional melting point polyester in the core layer of the present invention includes, for example, polyethylene terephthalate (PET). The term "non-reactive" in the phosphorus-containing non-reactive flame retardant means that the flame retardant does not react with the core layer polyester matrix. The phosphate ester flame retardant includes... (Referred to as: Non-reactive flame retardant 1), (Referred to as: Non-reactive flame retardant 2); the phosphorus-phenanthrene flame retardant is... (Referred to as: non-reactive flame retardant 3); These three phosphorus-containing non-reactive flame retardants have high flame retardant efficiency and good compatibility with the core layer polyester matrix.

[0063] In some preferred embodiments, the low-melting-point flame-retardant polyester core fiber has a tensile strength of 3.7–5.4 cN / dtex, an elongation at break of 12%–23%, and a limiting oxygen index of 34–46%.

[0064] Another aspect of the present invention provides a method for preparing the aforementioned low-melting-point flame-retardant polyester core-sheath fiber, comprising:

[0065] Low-melting-point polyester monomers, phosphorus-containing reactive flame retardants, and zero-dimensional nanoparticles are mixed, copolymerized, and then fed into an extruder through a pipeline for extrusion granulation to obtain a skin polyester material.

[0066] Conventional melting point polyester, phosphorus-containing non-reactive flame retardant, and modified two-dimensional nanosheets are mixed, melted, extruded, and granulated to obtain core layer polyester material;

[0067] Furthermore, the sheath polyester material and the core polyester material are subjected to melt spinning treatment to obtain low-melting-point flame-retardant polyester sheath-core fiber.

[0068] In some preferred embodiments, the low-melting-point polyester monomer includes terephthalic acid, isophthalic acid, ethylene glycol, diethylene glycol, and a phosphorus-containing flame-retardant monomer, wherein the phosphorus-containing flame-retardant monomer comprises 2-carboxyethylphenyl hypophosphite and [(6-oxo-6H-dibenzo[C,E][1,2]oxophosphoroxane-6-yl)methyl]succinic acid (DDP).

[0069] Furthermore, the molar ratio of 2-carboxyethylphenyl hypophosphite to [(6-oxo-6H-dibenzo[C,E][1,2]oxophosphoric acid-6-yl)methyl]succinic acid in the phosphorus-containing flame retardant monomer is (2-8):(8-2).

[0070] Furthermore, the molar ratio of 2-carboxyethylphenyl hypophosphite to [(6-oxo-6H-dibenzo[C,E][1,2]oxophosphoric acid-6-yl)methyl]succinic acid in the phosphorus-containing flame retardant monomer is (4-6):(6-4).

[0071] In some preferred embodiments, the process conditions for the melt spinning treatment include: a spinning temperature of 285℃~330℃, a spinning speed of 3000m / min~4200m / min; a drawing temperature of 65℃~80℃, and a drawing ratio of 2.4~3.2 times.

[0072] Furthermore, the spinning temperature is 300℃~315℃, the spinning speed is 3800m / min~4000m / min; the drawing temperature is 70℃~75℃, and the drawing ratio is 2.7~2.9 times.

[0073] In some preferred embodiments, the preparation method further includes drying the raw materials before melt spinning.

[0074] In some preferred embodiments, the preparation method further includes:

[0075] Two-dimensional nanosheets were subjected to ion exchange treatment to obtain two-dimensional nanosheets containing sodium ions.

[0076] Furthermore, the modified two-dimensional nanosheets containing sodium ions are mixed with melamine amide and stirred thoroughly, then phosphoric acid is added and the mixture is ultrasonically stirred to prepare the modified two-dimensional nanosheets.

[0077] In some more specific embodiments, the method for preparing the modified two-dimensional nanosheets includes:

[0078] Step 1: Disperse the two-dimensional nanosheets in a saturated sodium chloride solution to allow for sufficient ion exchange. Sodium ions can displace calcium ions from between the layers, resulting in two-dimensional nanosheets with sodium ions as the exchangeable cations between the layers. The exchange temperature is 25–85℃, and the exchange time is 1–24 h.

[0079] Step 2: The two-dimensional nanosheets (with sodium ions as the cations) obtained by displacement are redispersed in deionized water, melamine amide is added, and the mixture is stirred at high speed until fully mixed; the stirring temperature is 65-85℃, and the displacement time is 1-6 hours.

[0080] Step 3: Add excess phosphoric acid to the mixture prepared in Step 2, and stir with ultrasound at a constant temperature for several hours; wherein, the molar ratio of two-dimensional nanosheets (cation is sodium ion), melamine amide and phosphoric acid is 1:(0.1~0.3):(0.2~1.0), the reaction temperature is 30~90℃, and the reaction time is 1~12h;

[0081] Step 4: Let the reaction solution stand for a certain period of time, remove the supernatant to obtain the precipitate, wash it repeatedly with deionized water and filter it under reduced pressure to obtain melamine amide surface modified high aspect ratio two-dimensional nanosheets, i.e.: modified two-dimensional nanosheets; the standing time is 8-16 hours.

[0082] As a particularly preferred embodiment of this application, the method for preparing the low-melting-point flame-retardant polyester core fiber includes:

[0083] (1) Low-melting-point polyester monomers, phosphorus-containing flame-retardant segments and zero-dimensional nanoparticles are copolymerized at 235℃~245℃, extruded and granulated to obtain a skin layer low-melting-point polyester material (i.e. the aforementioned "skin layer polyester material") with a melting point of 105℃~125℃; the mass ratio of low-melting-point polyester monomers, phosphorus-containing flame-retardant segments and zero-dimensional nanoparticles is 100∶(5~7)∶(1~1.5).

[0084] (2) A conventional melting point polyester, a phosphorus-containing non-reactive flame retardant, and high aspect ratio two-dimensional nanosheets (the aforementioned "modified two-dimensional nanosheets") are mixed, melt-blended at 275℃~280℃, and extruded and granulated to obtain a core layer polyester material (i.e. the aforementioned "core layer polyester material") with a melting point of 245℃~255℃; the mass ratio of conventional melting point polyester, phosphorus-containing non-reactive flame retardant, and high aspect ratio two-dimensional nanosheets is 100∶(13-16)∶(1-1.5);

[0085] The intrinsic viscosity of the core layer polyester matrix is ​​between 0.70 and 0.75 dL / g; the phosphorus-containing non-reactive flame retardant is selected from non-reactive flame retardant 1, non-reactive flame retardant 2, or non-reactive flame retardant 3; the high aspect ratio two-dimensional nanosheets are selected from modified two-dimensional montmorillonite, attapulgite, illite, or sepiolite.

[0086] (3) Using the core polyester material as the inner core and the sheath polyester material as the outer sheath, low-melting-point flame-retardant polyester core-sheath fiber is obtained by melt spinning, wherein the sheath accounts for 25-35 wt% of the total mass of the low-melting-point flame-retardant polyester core-sheath fiber; wherein the spinning temperature is 300℃-315℃, the spinning speed is 3800m / min-4000m / min, the drawing temperature is 70℃-75℃, and the drawing ratio is 2.7-2.9 times.

[0087] Another aspect of the present invention provides the use of the aforementioned low-melting-point flame-retardant polyester core fiber in the automotive industry, rail transportation, building decoration, medical and health care, or home textile fields.

[0088] The technical solution of the present invention will be further described in detail below with reference to several preferred embodiments. These embodiments are implemented on the premise of the technical solution of the invention, and provide detailed implementation methods and specific operation processes. However, the protection scope of the present invention is not limited to the following embodiments.

[0089] Unless otherwise specified, the experimental materials used in the examples below can be purchased from conventional biochemical reagent companies.

[0090] The following examples illustrate the preparation method of melamine-modified two-dimensional nanosheets:

[0091] Step 1: Disperse two-dimensional nanosheets (nanoscale montmorillonite, attapulgite, illite, or sepiolite) in a saturated sodium chloride solution to allow for sufficient ion exchange. Sodium ions can displace calcium ions from between the layers, resulting in two-dimensional nanosheets with sodium ions as the exchangeable cation between the layers. The exchange temperature is 55℃ and the exchange time is 12h.

[0092] Step 2: The two-dimensional nanosheets (with sodium ions as the cations) obtained by displacement are redispersed in deionized water, melamine amide is added, and the mixture is stirred at high speed until fully mixed; the stirring temperature is 74℃ and the displacement time is 3 hours.

[0093] Step 3: Add excess phosphoric acid to the mixture prepared in Step 2, and stir with ultrasound at a constant temperature for several hours; wherein, the molar ratio of two-dimensional nanosheets (cation is sodium ion), melamine amide and phosphoric acid is 1:0.2:0.6, the reaction temperature is 64℃, and the reaction time is 7.2h.

[0094] Step 4: Let the reaction solution stand for a certain period of time, remove the supernatant to obtain the precipitate, wash it repeatedly with deionized water and filter under reduced pressure to obtain melamine amide surface-modified high aspect ratio two-dimensional nanosheets, i.e. modified two-dimensional nanosheets (including modified montmorillonite, modified attapulgite, modified illite or modified sepiolite); the standing time is 12h.

[0095] Example 1

[0096] The preparation method of low-melting-point flame-retardant polyester core fiber in this embodiment includes:

[0097] (1) Terephthalic acid, isophthalic acid, ethylene glycol, diethylene glycol, phosphorus-containing reactive flame retardant and zero-dimensional nanoparticles are copolymerized at 240°C, extruded and granulated to obtain a low-melting-point polyester material with a melting point of 115°C; the mass ratio of the sum of terephthalic acid, isophthalic acid, ethylene glycol, and diethylene glycol, the phosphorus-containing reactive flame retardant and the zero-dimensional nanoparticles is 100:6:1.25;

[0098] The molar ratio of terephthalic acid, isophthalic acid, ethylene glycol and diethylene glycol is 1:0.35:2.15:0.3; the phosphorus-containing reactive flame retardant is 2-carboxyethylphenyl hypophosphite and DDP, and the molar ratio of the two is 5:5; the zero-dimensional nanoparticles are nano-silica.

[0099] (2) A conventional melting point polyester, a phosphorus-containing non-reactive flame retardant and modified two-dimensional nanosheets are mixed, melt-blended at 277°C and extruded and granulated to obtain a core layer polyester material with a melting point of 250°C; the mass ratio of conventional melting point polyester, phosphorus-containing non-reactive flame retardant and modified two-dimensional nanosheets is 100:15:1.25.

[0100] Among them, the intrinsic viscosity of conventional melting point polyester is 0.72 dL / g; the phosphorus-containing non-reactive flame retardant is non-reactive flame retardant 1; and the modified two-dimensional nanosheets are modified montmorillonite.

[0101] (3) Using the core polyester material as the inner core and the sheath polyester material as the outer sheath, low-melting-point flame-retardant polyester core-sheath fiber was obtained by melt spinning, with the sheath accounting for 30 wt% of the total mass of the low-melting-point flame-retardant polyester core-sheath fiber; wherein, the spinning temperature was 307℃, the spinning speed was 3900 m / min, the drawing temperature was 72℃, and the drawing ratio was 2.8 times. The performance of the low-melting-point flame-retardant polyester core-sheath fiber was tested, and the test results are shown in Table 1.

[0102] Example 2

[0103] The preparation method of low-melting-point flame-retardant polyester core fiber in this embodiment includes:

[0104] (1) Terephthalic acid, isophthalic acid, ethylene glycol, diethylene glycol, phosphorus-containing reactive flame retardant and zero-dimensional nanoparticles are copolymerized at 245℃, extruded and granulated to obtain a low-melting-point polyester material with a melting point of 125℃; the mass ratio of the sum of terephthalic acid, isophthalic acid, ethylene glycol, and diethylene glycol, the phosphorus-containing reactive flame retardant and the zero-dimensional nanoparticles is 100:5:1.0;

[0105] The molar ratio of terephthalic acid, isophthalic acid, ethylene glycol and diethylene glycol is 1:0.3:2.1:0.25; the phosphorus-containing reactive flame retardant is 2-carboxyethylphenyl hypophosphite and DDP, and the molar ratio of the two is 5:5; the zero-dimensional nanoparticles are nano carbon black.

[0106] (2) A conventional melting point polyester, a phosphorus-containing non-reactive flame retardant and modified two-dimensional nanosheets are mixed, melt-blended at 275°C and extruded and granulated to obtain a core layer polyester material with a melting point of 245°C; the mass ratio of conventional melting point polyester, phosphorus-containing non-reactive flame retardant and modified two-dimensional nanosheets is 100:13:1.0.

[0107] Among them, the intrinsic viscosity of conventional melting point polyester is 0.70 dL / g; the phosphorus-containing non-reactive flame retardant is non-reactive flame retardant 2; and the modified two-dimensional nanosheets are modified attapulgite clay.

[0108] (3) Using the core polyester material as the inner core and the sheath polyester material as the outer sheath, low-melting-point flame-retardant polyester core-sheath fiber was obtained by melt spinning, with the sheath accounting for 25 wt% of the total mass of the low-melting-point flame-retardant polyester core-sheath fiber; wherein, the spinning temperature was 315℃, the spinning speed was 4000 m / min, the drawing temperature was 70℃, and the drawing ratio was 2.7 times. The performance of the low-melting-point flame-retardant polyester core-sheath fiber was tested, and the test results are shown in Table 1.

[0109] Example 3

[0110] The preparation method of low-melting-point flame-retardant polyester core fiber in this embodiment includes:

[0111] (1) Terephthalic acid, isophthalic acid, ethylene glycol, diethylene glycol, phosphorus-containing reactive flame retardant and zero-dimensional nanoparticles are copolymerized at 235°C, extruded and granulated to obtain a low-melting-point polyester material with a melting point of 105°C; the mass ratio of the sum of terephthalic acid, isophthalic acid, ethylene glycol, and diethylene glycol, the phosphorus-containing reactive flame retardant and the zero-dimensional nanoparticles is 100:7:1.5;

[0112] The molar ratio of terephthalic acid, isophthalic acid, ethylene glycol and diethylene glycol is 1:0.4:2.2:0.35; the phosphorus-containing flame-retardant segments are 2-carboxyethylphenyl hypophosphite and DDP, and the molar ratio of the two is 5:5; the zero-dimensional nanoparticles are nano-silica.

[0113] (2) A conventional melting point polyester, a phosphorus-containing non-reactive flame retardant and modified two-dimensional nanosheets are mixed, melt-blended at 280°C and extruded and granulated to obtain a core layer polyester material with a melting point of 255°C; the mass ratio of conventional melting point polyester, phosphorus-containing non-reactive flame retardant and modified two-dimensional nanosheets is 100:16:1.5.

[0114] The intrinsic viscosity of the conventional melting point polyester core layer is 0.75 dL / g; the phosphorus-containing non-reactive flame retardant is non-reactive flame retardant 3; and the modified two-dimensional nanosheets are modified illite.

[0115] (3) Using the core polyester material as the inner core and the sheath polyester material as the outer sheath, low-melting-point flame-retardant polyester core-sheath fiber was obtained by melt spinning, with the sheath accounting for 35 wt% of the total mass of the low-melting-point flame-retardant polyester core-sheath fiber; wherein, the spinning temperature was 300℃, the spinning speed was 3800 m / min, the drawing temperature was 75℃, and the drawing ratio was 2.9 times. The performance of the low-melting-point flame-retardant polyester core-sheath fiber was tested, and the test results are shown in Table 1.

[0116] Example 4

[0117] The preparation method of low-melting-point flame-retardant polyester core fiber in this embodiment includes:

[0118] (1) Terephthalic acid, isophthalic acid, ethylene glycol, diethylene glycol, phosphorus-containing reactive flame retardant and zero-dimensional nanoparticles are copolymerized at 252°C, extruded and granulated to obtain a low-melting-point polyester material with a melting point of 135°C; the mass ratio of the sum of terephthalic acid, isophthalic acid, ethylene glycol, and diethylene glycol, the phosphorus-containing reactive flame retardant and the zero-dimensional nanoparticles is 100:5:1.0;

[0119] The molar ratio of terephthalic acid, isophthalic acid, ethylene glycol and diethylene glycol is 1:0.25:2.0:0.27; the phosphorus-containing flame-retardant segments are 2-carboxyethylphenyl hypophosphite and DDP, and the molar ratio of the two is 4:6; the zero-dimensional nanoparticles are nano-silica.

[0120] (2) A conventional melting point polyester, a phosphorus-containing non-reactive flame retardant and modified two-dimensional nanosheets are mixed, melt-blended at 270°C and extruded and granulated to obtain a core layer polyester material with a melting point of 240°C; the mass ratio of conventional melting point polyester, phosphorus-containing non-reactive flame retardant and modified two-dimensional nanosheets is 100:13:1.0.

[0121] The intrinsic viscosity of the conventional melting point polyester core layer is 0.68 dL / g; the phosphorus-containing non-reactive flame retardant is non-reactive flame retardant 1; and the modified two-dimensional nanosheets are modified sepiolite.

[0122] (3) Using the core polyester material as the inner core and the sheath polyester material as the outer sheath, low-melting-point flame-retardant polyester core-sheath fiber was obtained by melt spinning, with the sheath accounting for 20 wt% of the total mass of the low-melting-point flame-retardant polyester core-sheath fiber; wherein, the spinning temperature was 322℃, the spinning speed was 4100 m / min, the drawing temperature was 67℃, and the drawing ratio was 2.5 times. The performance of the low-melting-point flame-retardant polyester core-sheath fiber was tested, and the test results are shown in Table 1.

[0123] Example 5

[0124] The preparation method of low-melting-point flame-retardant polyester core fiber in this embodiment includes:

[0125] (1) Terephthalic acid, isophthalic acid, ethylene glycol, diethylene glycol, phosphorus-containing reactive flame retardant and zero-dimensional nanoparticles are copolymerized at 227°C, extruded and granulated to obtain a low-melting-point polyester material with a melting point of 95°C; the mass ratio of the sum of terephthalic acid, isophthalic acid, ethylene glycol, and diethylene glycol, the phosphorus-containing reactive flame retardant and the zero-dimensional nanoparticles is 100:7:1.5;

[0126] The molar ratio of terephthalic acid, isophthalic acid, ethylene glycol and diethylene glycol is 1:0.45:2.3:0.32; the phosphorus-containing flame-retardant segments are 2-carboxyethylphenyl hypophosphite and DDP, and the molar ratio of the two is 6:4; the zero-dimensional nanoparticles are nano-silica and nano-carbon black.

[0127] (2) A conventional melting point polyester, a phosphorus-containing non-reactive flame retardant and modified two-dimensional nanosheets are mixed, melt-blended at 285°C and extruded and granulated to obtain a core layer polyester material with a melting point of 260°C; the mass ratio of conventional melting point polyester, phosphorus-containing non-reactive flame retardant and modified two-dimensional nanosheets is 100:16:1.5.

[0128] The intrinsic viscosity of the conventional melting point polyester core layer is 0.8 dL / g; the phosphorus-containing non-reactive flame retardant is non-reactive flame retardant 1; and the modified two-dimensional nanosheets are modified montmorillonite.

[0129] (3) Using the core polyester material as the inner core and the sheath polyester material as the outer sheath, low-melting-point flame-retardant polyester core-sheath fiber was obtained by melt spinning, with the sheath accounting for 40 wt% of the total mass of the low-melting-point flame-retardant polyester core-sheath fiber; wherein, the spinning temperature was 292℃, the spinning speed was 3400 m / min, the drawing temperature was 77℃, and the drawing ratio was 3.0 times. The performance of the low-melting-point flame-retardant polyester core-sheath fiber was tested, and the test results are shown in Table 1.

[0130] Example 6

[0131] The preparation method of low-melting-point flame-retardant polyester core fiber in this embodiment includes:

[0132] (1) Terephthalic acid, isophthalic acid, ethylene glycol, diethylene glycol, phosphorus-containing reactive flame retardant and zero-dimensional nanoparticles are copolymerized at 250°C, extruded and granulated to obtain a low-melting-point polyester material with a melting point of 130°C; the mass ratio of the sum of terephthalic acid, isophthalic acid, ethylene glycol, and diethylene glycol, the phosphorus-containing reactive flame retardant and the zero-dimensional nanoparticles is 100:4.5:0.7.

[0133] The molar ratio of terephthalic acid, isophthalic acid, ethylene glycol and diethylene glycol is 1:0.27:2.0:0.28; the phosphorus-containing flame-retardant segments are 2-carboxyethylphenyl hypophosphite and DDP, and the molar ratio of the two is 5:5; the zero-dimensional nanoparticles are nano-silica or nano-carbon black.

[0134] (2) A conventional melting point polyester, a phosphorus-containing non-reactive flame retardant and modified two-dimensional nanosheets are mixed, melt-blended at 272°C and extruded and granulated to obtain a core layer polyester material with a melting point of 243°C; the mass ratio of conventional melting point polyester, phosphorus-containing non-reactive flame retardant and modified two-dimensional nanosheets is 100:12:0.8.

[0135] The intrinsic viscosity of the conventional melting point polyester core layer is 0.69 dL / g; the phosphorus-containing non-reactive flame retardant is non-reactive flame retardant 2; and the modified two-dimensional nanosheets are modified attapulgite clay.

[0136] (3) Using the core polyester material as the inner core and the sheath polyester material as the outer sheath, low-melting-point flame-retardant polyester core-sheath fiber was obtained by melt spinning, with the sheath accounting for 22 wt% of the total mass of the low-melting-point flame-retardant polyester core-sheath fiber; wherein, the spinning temperature was 320℃, the spinning speed was 4150 m / min, the drawing temperature was 68℃, and the drawing ratio was 2.6 times. The performance of the low-melting-point flame-retardant polyester core-sheath fiber was tested, and the test results are shown in Table 1.

[0137] Example 7

[0138] The preparation method of low-melting-point flame-retardant polyester core fiber in this embodiment includes:

[0139] (1) Terephthalic acid, isophthalic acid, ethylene glycol, diethylene glycol, phosphorus-containing reactive flame retardant and zero-dimensional nanoparticles are copolymerized at 230°C, extruded and granulated to obtain a low-melting-point polyester material with a melting point of 110°C; the mass ratio of the sum of terephthalic acid, isophthalic acid, ethylene glycol, and diethylene glycol, the phosphorus-containing reactive flame retardant and the zero-dimensional nanoparticles is 100:7.5:1.7;

[0140] The molar ratio of terephthalic acid, isophthalic acid, ethylene glycol and diethylene glycol is 1:0.42:2.25:0.34; the phosphorus-containing flame-retardant segments of 2-carboxyethylphenyl hypophosphite are selected from 2-carboxyethylphenyl hypophosphite and DDP, and the molar ratio of the two is 5:5; the zero-dimensional nanoparticles are selected from nano-silica or nano-carbon black.

[0141] (2) A conventional melting point polyester, a phosphorus-containing non-reactive flame retardant and modified two-dimensional nanosheets are mixed, melt-blended at 282°C and extruded and granulated to obtain a core layer polyester material with a melting point of 256°C; the mass ratio of conventional melting point polyester, phosphorus-containing non-reactive flame retardant and modified two-dimensional nanosheets is 100:17:1.8.

[0142] The intrinsic viscosity of the conventional melting point polyester core layer is 0.77 dL / g; the phosphorus-containing non-reactive flame retardant is non-reactive flame retardant 2; and the modified two-dimensional nanosheets are modified attapulgite clay.

[0143] (3) Using the core polyester material as the inner core and the sheath polyester material as the outer sheath, low-melting-point flame-retardant polyester core-sheath fiber was obtained by melt spinning, with the sheath accounting for 38 wt% of the total mass of the low-melting-point flame-retardant polyester core-sheath fiber; wherein, the spinning temperature was 295℃, the spinning speed was 3600 m / min, the drawing temperature was 76℃, and the drawing ratio was 2.95 times. The performance of the low-melting-point flame-retardant polyester core-sheath fiber was tested, and the test results are shown in Table 1.

[0144] Example 8

[0145] The preparation method of low-melting-point flame-retardant polyester core fiber in this embodiment includes:

[0146] (1) Terephthalic acid, isophthalic acid, ethylene glycol, diethylene glycol, phosphorus-containing reactive flame retardant and zero-dimensional nanoparticles are copolymerized at 260°C, extruded and granulated to obtain a low-melting-point polyester material with a melting point of 145°C; the mass ratio of the sum of terephthalic acid, isophthalic acid, ethylene glycol, and diethylene glycol, the phosphorus-containing reactive flame retardant and the zero-dimensional nanoparticles is 100:3:0.1;

[0147] The molar ratio of terephthalic acid, isophthalic acid, ethylene glycol and diethylene glycol is 1:0.2:1.8:0.2; the phosphorus-containing flame-retardant segments are 2-carboxyethylphenyl hypophosphite and DDP, and the molar ratio of the two is 5:5; the zero-dimensional nanoparticles are nano-silica or nano-carbon black.

[0148] (2) A conventional melting point polyester, a phosphorus-containing non-reactive flame retardant and modified two-dimensional nanosheets are mixed, melt-blended at 265°C and extruded and granulated to obtain a core layer polyester material with a melting point of 235°C; the mass ratio of conventional melting point polyester, phosphorus-containing non-reactive flame retardant and modified two-dimensional nanosheets is 100:8:0.1.

[0149] The intrinsic viscosity of the conventional melting point polyester core layer is 0.65 dL / g; the phosphorus-containing non-reactive flame retardant is non-reactive flame retardant 3; and the modified two-dimensional nanosheets are a mixture of modified attapulgite and modified montmorillonite.

[0150] (3) Using the core polyester material as the inner core and the sheath polyester material as the outer sheath, low-melting-point flame-retardant polyester core-sheath fiber is obtained by melt spinning, with the sheath accounting for 10 wt% of the total mass of the low-melting-point flame-retardant polyester core-sheath fiber; wherein, the spinning temperature is 330℃, the spinning speed is 4200 m / min, the drawing temperature is 65℃, and the drawing ratio is 2.4 times. The performance of the low-melting-point flame-retardant polyester core-sheath fiber is tested, and the test results are shown in Table 1.

[0151] Example 9

[0152] The preparation method of low-melting-point flame-retardant polyester core fiber in this embodiment includes:

[0153] (1) Terephthalic acid, isophthalic acid, ethylene glycol, diethylene glycol, phosphorus-containing reactive flame retardant and zero-dimensional nanoparticles are copolymerized at 220°C, extruded and granulated to obtain a low-melting-point polyester material with a melting point of 85°C; the mass ratio of the sum of terephthalic acid, isophthalic acid, ethylene glycol, and diethylene glycol, the phosphorus-containing reactive flame retardant and the zero-dimensional nanoparticles is 100:10:3;

[0154] The molar ratio of terephthalic acid, isophthalic acid, ethylene glycol and diethylene glycol is 1:0.5:2.5:0.4; the phosphorus-containing flame-retardant segments are 2-carboxyethylphenyl hypophosphite and DDP, and the molar ratio of the two is 4:6; the zero-dimensional nanoparticles are nano-silica or nano-carbon black.

[0155] (2) A conventional melting point polyester, a phosphorus-containing non-reactive flame retardant and modified two-dimensional nanosheets are mixed, melt-blended at 290°C and extruded and granulated to obtain a core layer polyester material with a melting point of 265°C; the mass ratio of conventional melting point polyester, phosphorus-containing non-reactive flame retardant and modified two-dimensional nanosheets is 100:20:3.0.

[0156] The intrinsic viscosity of the conventional melting point polyester core layer is 0.85 dL / g; the phosphorus-containing non-reactive flame retardant is non-reactive flame retardant 3; and the modified two-dimensional nanosheets are modified attapulgite clay.

[0157] (3) Using the core polyester material as the inner core and the sheath polyester material as the outer sheath, low-melting-point flame-retardant polyester core-sheath fiber is obtained by melt spinning, with the sheath accounting for 50 wt% of the total mass of the low-melting-point flame-retardant polyester core-sheath fiber; wherein, the spinning temperature is 285℃, the spinning speed is 3000 m / min, the drawing temperature is 80℃, and the drawing ratio is 3.2 times. The performance of the low-melting-point flame-retardant polyester core-sheath fiber is tested, and the test results are shown in Table 1.

[0158] Example 10

[0159] The preparation method of low-melting-point flame-retardant polyester core fiber in this embodiment includes:

[0160] (1) Terephthalic acid, isophthalic acid, ethylene glycol, diethylene glycol, phosphorus-containing reactive flame retardant and zero-dimensional nanoparticles are copolymerized at 256°C, extruded and granulated to obtain a low-melting-point polyester material with a melting point of 140°C; the mass ratio of the sum of terephthalic acid, isophthalic acid, ethylene glycol, and diethylene glycol, the phosphorus-containing reactive flame retardant and the zero-dimensional nanoparticles is 100:3.5:0.3;

[0161] The molar ratio of terephthalic acid, isophthalic acid, ethylene glycol and diethylene glycol is 1:0.22:1.9:0.22; the phosphorus-containing flame-retardant segments are 2-carboxyethylphenyl hypophosphite and DDP, and the molar ratio of the two is 6:4; the zero-dimensional nanoparticles are nano-silica or nano-carbon black.

[0162] (2) A conventional melting point polyester, a phosphorus-containing non-reactive flame retardant and modified two-dimensional nanosheets are mixed, melt-blended at 267°C and extruded and granulated to obtain a core layer polyester material with a melting point of 236°C; the mass ratio of conventional melting point polyester, phosphorus-containing non-reactive flame retardant and modified two-dimensional nanosheets is 100:9:0.3.

[0163] The intrinsic viscosity of the conventional melting point polyester core layer is 0.66 dL / g; the phosphorus-containing non-reactive flame retardant is non-reactive flame retardant 1; and the modified two-dimensional nanosheets are modified sepiolite.

[0164] (3) Using the core polyester material as the inner core and the sheath polyester material as the outer sheath, low-melting-point flame-retardant polyester core-sheath fiber was obtained by melt spinning, with the sheath accounting for 15 wt% of the total mass of the low-melting-point flame-retardant polyester core-sheath fiber; wherein, the spinning temperature was 325℃, the spinning speed was 4150 m / min, the drawing temperature was 66℃, and the drawing ratio was 2.45 times. The performance of the low-melting-point flame-retardant polyester core-sheath fiber was tested, and the test results are shown in Table 1.

[0165] Example 11

[0166] The preparation method of low-melting-point flame-retardant polyester core fiber in this embodiment includes:

[0167] (1) Terephthalic acid, isophthalic acid, ethylene glycol, diethylene glycol, phosphorus-containing reactive flame retardant and zero-dimensional nanoparticles are copolymerized at 224℃, extruded and granulated to obtain a low-melting-point polyester material with a melting point of 90℃; the mass ratio of the sum of terephthalic acid, isophthalic acid, ethylene glycol, and diethylene glycol, the phosphorus-containing reactive flame retardant and the zero-dimensional nanoparticles is 100:9:2.5;

[0168] The molar ratio of terephthalic acid, isophthalic acid, ethylene glycol and diethylene glycol is 1:0.46:2.4:0.36; the phosphorus-containing flame-retardant segments are 2-carboxyethylphenyl hypophosphite and DDP, and the molar ratio of the two is 7:3; the zero-dimensional nanoparticles are nano-silica.

[0169] (2) A conventional melting point polyester, a phosphorus-containing non-reactive flame retardant and modified two-dimensional nanosheets are mixed, melt-blended at 284°C and extruded and granulated to obtain a core layer polyester material with a melting point of 257°C; the mass ratio of conventional melting point polyester, phosphorus-containing non-reactive flame retardant and modified two-dimensional nanosheets is 100:19:2.5.

[0170] The intrinsic viscosity of the conventional melting point polyester core layer is 0.83 dL / g; the phosphorus-containing non-reactive flame retardant is non-reactive flame retardant 2; and the modified two-dimensional nanosheets are modified attapulgite clay.

[0171] (3) Using the core polyester material as the inner core and the sheath polyester material as the outer sheath, low-melting-point flame-retardant polyester core-sheath fiber was obtained by melt spinning, with the sheath accounting for 12wt% of the total mass of the low-melting-point flame-retardant polyester core-sheath fiber; wherein, the spinning temperature was 290℃, the spinning speed was 3300m / min, the drawing temperature was 78℃, and the drawing ratio was 3.1 times. The performance of the low-melting-point flame-retardant polyester core-sheath fiber was tested, and the test results are shown in Table 1.

[0172] Example 12

[0173] The preparation method of low-melting-point flame-retardant polyester core fiber in this embodiment includes:

[0174] (1) Terephthalic acid, isophthalic acid, ethylene glycol, diethylene glycol, phosphorus-containing reactive flame retardant and zero-dimensional nanoparticles are copolymerized at 259°C, extruded and granulated to obtain a low-melting-point polyester material with a melting point of 143°C; the mass ratio of the sum of terephthalic acid, isophthalic acid, ethylene glycol, and diethylene glycol, the phosphorus-containing reactive flame retardant and the zero-dimensional nanoparticles is 100:3.2:0.2;

[0175] The molar ratio of terephthalic acid, isophthalic acid, ethylene glycol and diethylene glycol is 1:0.24:1.95:0.24; the phosphorus-containing flame-retardant segments are 2-carboxyethylphenyl hypophosphite and DDP, and the molar ratio of the two is 8:2; the zero-dimensional nanoparticles are nano-silica and nano-carbon black.

[0176] (2) A conventional melting point polyester, a phosphorus-containing non-reactive flame retardant and modified two-dimensional nanosheets are mixed, melt-blended at 269°C and extruded and granulated to obtain a core layer polyester material with a melting point of 238°C; the mass ratio of conventional melting point polyester, phosphorus-containing non-reactive flame retardant and modified two-dimensional nanosheets is 100:8.5:0.2.

[0177] The intrinsic viscosity of the conventional melting point polyester core layer is 0.67 dL / g; the phosphorus-containing non-reactive flame retardant is non-reactive flame retardant 1; and the modified two-dimensional nanosheets are modified attapulgite clay.

[0178] (3) Using the core polyester material as the inner core and the sheath polyester material as the outer sheath, low-melting-point flame-retardant polyester core-sheath fiber was obtained by melt spinning, with the sheath accounting for 45 wt% of the total mass of the low-melting-point flame-retardant polyester core-sheath fiber; wherein, the spinning temperature was 329℃, the spinning speed was 4160 m / min, the drawing temperature was 65℃, and the drawing ratio was 2.47 times. The performance of the low-melting-point flame-retardant polyester core-sheath fiber was tested, and the test results are shown in Table 1.

[0179] Example 13

[0180] The preparation method of low-melting-point flame-retardant polyester core fiber in this embodiment includes:

[0181] (1) Terephthalic acid, isophthalic acid, ethylene glycol, diethylene glycol, phosphorus-containing reactive flame retardant and zero-dimensional nanoparticles are copolymerized at 222℃, extruded and granulated to obtain a low-melting-point polyester material with a skin layer and a melting point of 87℃; the mass ratio of the sum of terephthalic acid, isophthalic acid, ethylene glycol, and diethylene glycol, the phosphorus-containing reactive flame retardant and the zero-dimensional nanoparticles is 100:9.5:2.8;

[0182] The molar ratio of terephthalic acid, isophthalic acid, ethylene glycol and diethylene glycol is 1:0.48:2.45:0.39; the phosphorus-containing flame-retardant segments are 2-carboxyethylphenyl hypophosphite and DDP, and the molar ratio of the two is 2:8; the zero-dimensional nanoparticles are nano carbon black.

[0183] (2) A conventional melting point polyester, a phosphorus-containing non-reactive flame retardant and modified two-dimensional nanosheets are mixed, melt-blended at 289°C and extruded and granulated to obtain a core layer polyester material with a melting point of 263°C; the mass ratio of conventional melting point polyester, phosphorus-containing non-reactive flame retardant and modified two-dimensional nanosheets is 100:18.5:2.8.

[0184] The intrinsic viscosity of the conventional melting point polyester core layer is 0.84 dL / g; the phosphorus-containing non-reactive flame retardant is non-reactive flame retardant 3; and the modified two-dimensional nanosheets are modified attapulgite clay.

[0185] (3) Using the core polyester material as the inner core and the sheath polyester material as the outer sheath, low-melting-point flame-retardant polyester core-sheath fiber was obtained by melt spinning, with the sheath accounting for 48 wt% of the total mass of the low-melting-point flame-retardant polyester core-sheath fiber; wherein, the spinning temperature was 288℃, the spinning speed was 3100 m / min, the drawing temperature was 79℃, and the drawing ratio was 3.15 times. The performance of the low-melting-point flame-retardant polyester core-sheath fiber was tested, and the test results are shown in Table 1.

[0186] Comparative Example 1

[0187] The method was followed in Example 1, except that "spinning temperature of 307°C" was replaced with "370°C". The test results are shown in Table 1.

[0188] Comparative Example 2

[0189] The method was followed in Example 1, except that "spinning speed of 3900 m / min" was replaced with "4600 m / min". The test results are shown in Table 1.

[0190] Comparative Example 3

[0191] The method was followed in Example 1, except that "drawing temperature of 72°C" was replaced with "115°C". The test results are shown in Table 1.

[0192] Comparative Example 4

[0193] The method was followed in Example 1, except that "drawing ratio of 2.8 times" was replaced with "4.0 times". The test results are shown in Table 1.

[0194] Comparative Example 5

[0195] The method was the same as in Example 1, except that the modified two-dimensional nanosheets did not undergo surface modification with melamine amide; instead, the original two-dimensional nanosheets were used. The test results are shown in Table 1.

[0196] Comparative Example 6

[0197] The method of Example 1 was followed, except that "copolymerization of terephthalic acid, isophthalic acid, ethylene glycol, diethylene glycol, phosphorus-containing reactive flame retardant and zero-dimensional nanoparticles at 240°C" was replaced with "280°C". The test results are shown in Table 1.

[0198] Comparative Example 7

[0199] The method of Example 1 was followed, except that "conventional melting point polyester, phosphorus-containing non-reactive flame retardant and high aspect ratio two-dimensional nanosheets were melt-blended at 290°C" was replaced with "350°C". The test results are shown in Table 1.

[0200] Comparative Example 8

[0201] The method is the same as in Example 1, except that zero-dimensional nanoparticles (silica nanoparticles) are not used. The detection results are shown in Table 1.

[0202] Comparative Example 9

[0203] The method is the same as in Example 1, except that the modified two-dimensional nanosheets are not used. The test results are shown in Table 1.

[0204] Comparative Example 10

[0205] The method is the same as in Example 1, except that only 2-carboxyethylphenyl hypophosphite is used as the phosphorus-containing reactive flame retardant. The test results are shown in Table 1.

[0206] Comparative Example 11

[0207] The method was the same as in Example 1, except that only DDP was used as the phosphorus-containing reactive flame retardant. The test results are shown in Table 1.

[0208] Comparative Example 12

[0209] The method is the same as in Example 1, except that a phosphorus-containing non-reactive flame retardant is missing. The test results are shown in Table 1.

[0210] Table 1. Performance characterization results of the low-melting-point flame-retardant polyester core fibers prepared in Examples 1-13 and Comparative Examples 1-12.

[0211]

[0212]

[0213] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0214] It should be understood that the technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made to the technical solutions of the present invention without departing from the spirit and scope of the claims are within the scope of protection of the present invention.

Claims

1. A low-melting-point flame-retardant polyester core-sheath fiber, characterized in that, Including the cortex and core; The skin layer comprises a low-melting-point polyester and zero-dimensional nanoparticles dispersed in the low-melting-point polyester. The molecular structure of the low-melting-point polyester includes polyester segments and phosphorus-containing flame-retardant segments. The phosphorus-containing flame-retardant segments are derived from 2-carboxyethylphenyl hypophosphite and [(6-oxo-6H-dibenzo[C,E][1,2]oxophosphoroxane-6-yl)methyl]succinic acid. The melting point of the low-melting-point polyester is 85℃ to 145℃. The zero-dimensional nanoparticles include any one or more combinations of nano-silica and nano-carbon black. The core layer comprises a conventional melting point polyester, a phosphorus-containing non-reactive flame retardant dispersed in the conventional melting point polyester, and modified two-dimensional nanosheets. The phosphorus-containing non-reactive flame retardant includes any one or more combinations of phosphate ester flame retardants and phosphaphenanthrene flame retardants. The melting point of the conventional melting point polyester is 235℃~265℃. The modified two-dimensional nanosheets are obtained by surface modification treatment of the two-dimensional nanosheets with melamine-amide. The two-dimensional nanosheets include any one or more combinations of nano-sized montmorillonite, attapulgite, illite, and sepiolite. The preparation method of the low-melting-point flame-retardant polyester core fiber includes: Low-melting-point polyester monomers, phosphorus-containing reactive flame retardants, and zero-dimensional nanoparticles are mixed and copolymerized at 235℃~245℃, followed by extrusion granulation to obtain a skin-layer polyester material; the low-melting-point polyester monomers include terephthalic acid, isophthalic acid, ethylene glycol, diethylene glycol, and phosphorus-containing flame retardant monomers; wherein, the phosphorus-containing flame retardant monomers include 2-carboxyethylphenyl hypophosphite and [(6-oxo-6H-dibenzo[C,E][1,2]oxophosphoric acid hexane-6-yl)methyl]succinic acid; Conventional melting point polyester, phosphorus-containing non-reactive flame retardant, and modified two-dimensional nanosheets are mixed, melted at 275℃~280℃, and extruded and granulated to obtain core layer polyester material. Furthermore, the sheath polyester material and the core polyester material are subjected to melt spinning treatment to obtain low-melting-point flame-retardant polyester sheath-core fiber; the process conditions for the melt spinning treatment include: spinning temperature of 285℃~330℃, spinning speed of 3000m / min~4200m / min; drawing temperature of 65℃~80℃, and drawing ratio of 2.4~3.2 times; The method for preparing the modified two-dimensional nanosheets includes: Two-dimensional nanosheets were subjected to ion exchange treatment to obtain two-dimensional nanosheets containing sodium ions. The two-dimensional nanosheets containing sodium ions were mixed with melamine-amide and stirred thoroughly. Then, phosphoric acid was added and the mixture was ultrasonically stirred to prepare the modified two-dimensional nanosheets.

2. The low-melting-point flame-retardant polyester core fiber according to claim 1, characterized in that, The skin layer comprises the following components by weight: 100 parts low-melting-point polyester and 0.1 to 3 parts zero-dimensional nanoparticles; And / or, the sheath layer accounts for 10 to 50 wt% of the total mass of the low-melting-point flame-retardant polyester core fiber.

3. The low-melting-point flame-retardant polyester core fiber according to claim 2, characterized in that: The mass ratio of low-melting-point polyester to zero-dimensional nanoparticles in the skin layer is 100:(1-1.5).

4. The low-melting-point flame-retardant polyester core fiber according to claim 1, characterized in that: The intrinsic viscosity of the low-melting-point polyester is 0.54–0.68 dL / g; And / or, the polyester segments include terephthalic acid segments, isophthalic acid segments, ethylene glycol segments, and diethylene glycol segments; the molar ratio of the terephthalic acid segments, isophthalic acid segments, ethylene glycol segments, and diethylene glycol segments is 1:(0.2-0.5):(1.8-2.5):(0.2-0.4); And / or, the mass ratio of the low-melting-point polyester to the phosphorus-containing flame-retardant segment in the low-melting-point polyester is 100:(3-10).

5. The low-melting-point flame-retardant polyester core fiber according to claim 4, characterized in that: The intrinsic viscosity of the low-melting-point polyester is 0.58–0.66 dL / g; And / or, the mass ratio of the low-melting-point polyester to the phosphorus-containing flame-retardant segment in the low-melting-point polyester is 100:(5-7).

6. The low-melting-point flame-retardant polyester core fiber according to claim 1, characterized in that, The core layer comprises the following components by weight: 100 parts conventional melting point polyester, 8-20 parts phosphorus-containing non-reactive flame retardant, and 0.1-3 parts modified two-dimensional nanosheets.

7. The low-melting-point flame-retardant polyester core fiber according to claim 6, characterized in that: The mass ratio of conventional melting point polyester to phosphorus-containing non-reactive flame retardant in the core layer is 100:(13-16); And / or, the mass ratio of conventional melting point polyester to modified two-dimensional nanosheets in the core layer is 100:(1-1.5).

8. The low-melting-point flame-retardant polyester core fiber according to claim 1, characterized in that: The molecular structure of the conventional melting point polyester includes terephthalic acid segments and ethylene glycol segments. And / or, the intrinsic viscosity of the conventional melting point polyester is in the range of 0.65 to 0.85 dL / g; And / or, the phosphate ester flame retardant comprises a compound having the structure shown in formula (I) or formula (II): And / or, the phosphorus-phenanthrene flame retardant comprises a compound having the structure shown in formula (III):

9. The low-melting-point flame-retardant polyester core fiber according to claim 1, characterized in that: The low-melting-point flame-retardant polyester core fiber has a tensile strength of 3.7–5.4 cN / dtex, an elongation at break of 12%–23%, and a limiting oxygen index of 34–46%.

10. The low-melting-point flame-retardant polyester core fiber according to claim 1, characterized in that: The molar ratio of 2-carboxyethylphenyl hypophosphite to [(6-oxo-6H-dibenzo[C,E][1,2]oxophosphazenecyclo-6-yl)methyl]succinic acid in the phosphorus-containing flame retardant monomer is (2-8):(8-2).

11. The low-melting-point flame-retardant polyester core fiber according to claim 10, characterized in that: The molar ratio of 2-carboxyethylphenyl hypophosphite to [(6-oxo-6H-dibenzo[C,E][1,2]oxophosphazenecyclo-6-yl)methyl]succinic acid in the phosphorus-containing flame retardant monomer is (4-6):(6-4).

12. The low-melting-point flame-retardant polyester core fiber according to claim 1, characterized in that, The process conditions for the melt spinning treatment include: a spinning temperature of 300℃~315℃, a spinning speed of 3800m / min~4000m / min; a drawing temperature of 70℃~75℃, and a drawing ratio of 2.7~2.9 times.

13. Use of the low-melting-point flame-retardant polyester core fiber according to any one of claims 1-12 in the automotive industry, rail transportation, building decoration, medical and health care, or home textile fields.

Images