Antifibrillated polyester monofilament and preparation method thereof

Abstract

The invention belongs to the technical field of polyester monofilament preparation, and particularly relates to an antifibrillated polyester monofilament and a preparation method thereof. According to the preparation method, on the basis of a conventional preparation process, the anti-fibrillating polyester monofilament is prepared by performing ultraviolet crosslinking post-treatment on the polyester monofilament. The prepared polyester monofilament improves the overhigh crystallinity of a fiber skin layer and improves the interaction force between fibril molecular chains by increasing crosslinking sites, so that the polyester monofilament has excellent fibrillation resistance, the fibrillation resistance is improved by more than or equal to 500%, the mechanical property is not obviously influenced (the retention rate of the mechanical property is more than or equal to 90%), and the polyester monofilament has a wide market application prospect. Besides, compared with conventional thermal crosslinking, bi-component spinning and other methods, the ultraviolet crosslinking post-treatment method adopted in the invention has the advantages of less capital input, safe, simple, convenient and rapid operation, almost no pollution to the environment, small damage degree to the mechanical properties of the polyester monofilament, and suitableness for industrial large-scale production.

Description

Technical Field

[0001] The present invention belongs to the technical field of polyester monofilament preparation, and specifically relates to a polyester monofilament resistant to fibrillation and a preparation method thereof, in particular, a method for improving the anti-fibrillation ability of polyester monofilament and retaining mechanical properties by post-treating the polyester monofilament with ultraviolet crosslinking. Background Art

[0002] With the continuous development of the field of electronic circuit printing, natural fibers such as silk that were previously used with high prices and low performance can no longer meet today's demand for high-precision printing. The screen required to achieve high-resolution printing should have excellent properties such as wear resistance, resilience, and dimensional stability. The monofilaments of the woven screen should also have the characteristics of high strength, high modulus, and fine fiber. In recent years, screens woven from synthetic fibers such as polyester and nylon with reasonable costs and stable performance have been favored. Compared with nylon screens, polyester monofilament woven screens have better heat resistance and stability, less changes after moisture absorption, and are cheaper, and are widely used.

[0003] However, the polyester monofilament used for weaving printing screens will inevitably fibrillate during production and use. The reason is that the thermal conductivity of polymers is poor. The radial temperature difference of the fiber caused by the spinning process such as side blowing, heat stretching, and heat setting affects the uneven melt viscosity, forming a radial viscosity gradient, affecting the distribution of radial tension of the fiber, and resulting in the formation of a fiber skin-core structure. Due to the high orientation of the cortex along the axial direction of the fiber, after mechanical friction, the cortex is prone to stress concentration and damage, splitting along the axial direction, causing the fiber to fibrillate. Screen printing uses the screen as the base. Due to the high mesh requirements of the screen, the polyester monofilament needs to be woven at a high density. In the process of weaving into the printing screen, the original silk will be repeatedly rubbed and fibrillated, which will affect the quality of the entire screen, resulting in defects when the electronic circuit is copied by photosensitive, which is contrary to the high precision requirements required for printing. Unfortunately, the fibrillation problem is easily overlooked in other application scenarios of polyester monofilament, resulting in it not being widely concerned and solved.

[0004] At present, with the efforts of previous scholars, some effective solutions have been explored for the problem of polyester monofilament fibrillation. The patent of polyester monofilament for mesh yarn with publication number CN1333846A reported that the occurrence of scum (fibrillation) on the surface of monofilament was suppressed by using a skin-core composite polyester monofilament with conventional polyester as the core layer and polyalkylene oxide copolyester as the skin layer. However, the requirements of the two-component composite monofilament on the production process and production equipment are higher than those of the single-component monofilament, which is not cost-effective, and the uniformity and stability of the skin-core structure of the monofilament are difficult to guarantee. In the research document "Enzymatic Modification of Polyester", serine esterase was used to modify the surface of polyester, and the polymer main chain was broken by hydrolyzing the ester bond, so that the soluble polymer fragments fell off, which can significantly reduce the phenomenon of polyester fibrillation and fuzzing. However, its hydrolysis efficiency is low, the treatment conditions are harsh and difficult to control, and the fiber breaking strength and elongation at break after enzyme treatment are significantly reduced, so it is not suitable for preparing industrial polyester monofilament. In addition, since Lyocell fibers also have the typical skin-core structure characteristics that are extremely easy to fibrillate, they have been widely studied in terms of anti-fibrillation, which may provide ideas and insights for the anti-fibrillation of polyester monofilaments to a certain extent. The document "Defibrillation Method of Lyocell Fibers" states that alkaline treatment of fibers with sodium hydroxide or tetramethylammonium hydroxide can cause Lyocell fibers to plasticize and reduce the fiber fibrillation tendency by at least about 40%. In addition, the fibers can also be cross-linked. In the document "The Effect of Cross-linking Treatment on the Anti-fibrillation Performance of Lyocell Fibers", a multi-functional cross-linking agent was used to cross-link the primary fibers obtained after a water bath. The size of the base fibers and the base fiber aggregate bundles were significantly reduced and the content increased. The anti-fibrillation ability was significantly higher than that of those without cross-linking treatment, and the mechanical properties were not significantly affected. The invention patent of publication number CN104005225A, a method for reducing the fibrillation tendency of lyocell cellulose fibers, also mentions the use of dialdehyde cross-linking agents with carbon chains in the range of C2-C6, metal salts or organic acid catalysts and surfactants for post-crosslinking treatment to effectively reduce the fibrillation tendency of lyocell cellulose fibers.

[0005] However, the production of Lyocell fiber is a physical process in which cellulose is first dissolved and then precipitated in an organic solvent NMMO (N-methylmorpholine-N-oxide), using a dry-jet wet spinning process. In addition, the molecular chains of Lyocell fibers are interconnected by a large number of hydrogen bonds, which makes it easy for water molecules to enter the fiber in a wet environment, destroying the lateral binding force between molecules, resulting in Lyocell fibers being almost entirely core layers, with a thinner cortex layer, and the core layer consisting of highly crystalline, oriented giant fibrils and amorphous regions, and fibrillation usually occurring between the fibrils in the core layer. Therefore, a wet crosslinking method is usually used to allow the crosslinking agent to penetrate into the fiber (core layer) after the fiber swells, and chemical bonds are formed between the crosslinking agent molecules and the hydroxyl groups on the Lyocell fiber, thereby achieving an anti-fibrillation effect by increasing the interaction force between the fibrils. In contrast, polyester molecular chains are linked by ester bonds, and the polyester monofilaments obtained after melt spinning have relatively uniform crystalline and amorphous regions and strong interfacial binding forces, and the interaction force between the molecular chains in the core layer is strong, and fibrillation mainly occurs in the highly crystalline oriented cortex layer. In addition, in most common cross-linking situations, water is usually more likely to have an adverse effect on cross-linking. In summary, since the chemical structure and production process of Lyocell fiber are significantly different from those of polyester fiber, the above-mentioned cross-linking method of Lyocell fiber is difficult to apply to polyester monofilament.

[0006] Therefore, inventing a polyester monofilament that is effectively resistant to fibrillation, has excellent mechanical properties and is low in cost is of great significance for the high-end printing industry to achieve high-precision printing. Summary of the invention

[0007] The purpose of the present invention is to provide a polyester monofilament that is resistant to fibrillation and a preparation method thereof in view of the deficiencies in the prior art of polyester monofilaments, and in particular to a polyester monofilament that is first prepared by melt spinning with excellent mechanical properties, and then treated with a photocrosslinking agent and a hydrogen abstraction photoinitiator after drawing, and obtained by heat treatment and ultraviolet crosslinking modification to obtain a polyester monofilament that is resistant to fibrillation and a preparation method thereof. The resistant polyester monofilament described in the present invention is treated with ultraviolet crosslinking, and the ultraviolet crosslinking treatment is carried out by using a photocrosslinking agent and a photoinitiator to perform ultraviolet crosslinking modification on the polyester monofilament before winding, which can effectively improve the structural differences caused by the spinning process, and improve the anti-fibrillation ability of the polyester monofilament while maintaining the mechanical properties, so as to meet the high-quality requirements of the high-end printing industry for printing screens.

[0008] To achieve the above purpose, the technical solution adopted by the present invention is:

[0009] One of the purposes of the present invention is to provide a method for preparing anti-fibrillation polyester monofilaments, wherein the polyester monofilaments obtained after drawing are subjected to ultraviolet crosslinking post-treatment based on a conventional preparation process to obtain anti-fibrillation polyester monofilaments. The ultraviolet crosslinking treatment enables the polyester monofilaments to be crosslinked and modified, and the prepared polyester monofilaments have stable and lasting anti-fibrillation ability, and the mechanical properties are not affected.

[0010] Preferably, the UV cross-linking treatment comprises the following steps:

[0011] (1) dipping the polyester monofilament obtained after drawing and heat setting into a solution containing a crosslinking agent;

[0012] (2) heat treating the impregnated polyester monofilament;

[0013] (3) The polyester monofilament after the heat treatment is subjected to a UV cross-linking step to complete the UV cross-linking treatment.

[0014] Preferably, in the solution containing the crosslinking agent in step (1), the concentration of the crosslinking agent is 0.5 to 2 wt %; more preferably, the crosslinking agent is a photocrosslinking agent selected from at least one of triallyl isocyanurate (TAIC), triallyl cyanurate (TAC), pentaerythritol triallyl propionate (PETA), and glycidyl methacrylate (GMA).

[0015] Preferably, the solution containing the crosslinking agent in step (1) further contains a photoinitiator, and the concentration of the photoinitiator in the solution is 0.25-1 wt%; more preferably, the photoinitiator is a hydrogen abstraction type initiator, more preferably at least one selected from benzophenone (BP), 4-chlorobenzophenone (4-CBP), thioxanthone (TX), and isopropylthioxanthone (ITX). The presence of the photoinitiator can make the crosslinking reaction proceed more quickly.

[0016] Preferably, in the solution containing the cross-linking agent in step (1), the solvent is at least one of ethyl acetate, acetone, tetrahydrofuran and dichloromethane.

[0017] More preferably, the crosslinking agent is triallyl isocyanurate (TAIC), and the photoinitiator is benzophenone (BP).

[0018] More preferably, the solution containing the crosslinking agent in step (1) is a mixed solution containing 0.5-2 wt% of the crosslinking agent and 0.25-1 wt% of the photoinitiator. The photocrosslinking agent and the photoinitiator are used in combination, and the adapted initiation system can enable the crosslinking reaction to be completed quickly at the initial reaction stage, effectively improving the rate and crosslinking depth of ultraviolet light crosslinking.

[0019] Preferably, the dipping in step (1) is for 20 to 30 seconds, followed by subsequent heat treatment and UV cross-linking steps.

[0020] Preferably, the treatment temperature of the heat treatment in step (2) is 70-90°C, and the treatment time is not less than 5 minutes, more preferably 5-10 minutes. A more preferred heat treatment method is to perform heat treatment under hot air to remove the solvent in the photocrosslinking system. The heat treatment process can prevent the residual ethyl acetate solvent from interfering with the photocrosslinking reaction, and make the photocrosslinker and photoinitiator fully, firmly and evenly attached to the fiber surface. At the same time, the crosslinker molecules are more likely to diffuse into the fiber cortex through the micropores on the surface of the monofilament through more intense molecular thermal motion, and increase the concentration and activity of the photocrosslinker, so that it reacts more concentratedly with the active sites on the fiber, effectively improving the efficiency of the subsequent ultraviolet light crosslinking treatment. If the heat treatment temperature is too high, the photocrosslinker and photoinitiator will volatilize, affecting the subsequent photocrosslinking effect, and will also cause the highly oriented polyester molecular chain to de-orient and degrade, resulting in impaired mechanical properties. If the heat treatment time is too short, the undried composite solution containing the photocrosslinker and initiator will easily flow or migrate on the fiber, making it difficult to ensure the uniformity of the photocrosslinking reaction. The presence of residual solvents may also affect the photocrosslinking effect. Excessive heat treatment time will also cause the volatilization of the crosslinker / initiator and induce unnecessary side reactions, reducing the crosslinking effect and causing unnecessary cost consumption. Similarly, if a thermal crosslinking method is used to bond and crosslink the crosslinker with the polyester fiber, for example, the DCP thermal crosslinking temperature range is between 150-200°C, and crosslinking takes several hours, and the deorientation and thermal degradation caused by high temperature will directly affect the strength, toughness and dimensional stability of the fiber, and it is time-consuming and costly.

[0021] Preferably, the ultraviolet cross-linking step in step (3) uses ultraviolet lamp irradiation, and the ultraviolet light wavelength range is 280-400nm.

[0022] Preferably, the UV crosslinking temperature is 55-65°C, and the treatment time is 120-150s. The role of the UV crosslinking temperature is to increase the rate of the UV crosslinking reaction, thereby shortening the UV treatment time. The UV crosslinking process can also be carried out at room temperature, but it takes a long time. In addition, if the irradiation time is insufficient, the crosslinking reaction fails to proceed fully; if the irradiation time is too long or the concentration of the crosslinking solvent is too high, the mechanical properties of the polyester monofilament will be reduced and the ability to resist fibrillation will be reduced. Specifically, a comprehensive balance can be made based on actual working conditions and economic costs.

[0023] Preferably, the conventional preparation process of polyester monofilament comprises the steps of drying polyester slices, melt extrusion, cooling, oiling, drawing and winding.

[0024] Specific:

[0025] Raw material preparation: Select appropriate polyester chips as raw materials and ensure that their quality meets the requirements.

[0026] Drying and dehumidification: The polyester chips are dried and dehumidified to remove moisture to ensure the stability of subsequent processing.

[0027] Melt extrusion: The dried polyester chips are added to the extruder and melted by heating.

[0028] Cooling: The ejected thin stream is cooled by air cooling or water cooling to solidify it into a monofilament.

[0029] Oiling: Apply a layer of oil to the surface of the monofilament to increase its softness and smoothness and reduce friction.

[0030] Drawing: Stretching the cooled monofilament to increase its strength and toughness. Drawing can be done in multiple stages, usually including hot water drawing, hot air drawing, heat setting and other steps.

[0031] Winding: Wind the stretched monofilament into a roll for subsequent processing and use.

[0032] More preferably, the main process parameters are as follows:

[0033] The drying temperature is 150-170°C;

[0034] The extrusion temperature is 280-300°C;

[0035] The cooling water temperature is 70-80°C;

[0036] The oil concentration of the oiling agent is 5 to 15%;

[0037] The drafting process:

[0038] One roller: speed is 20-25m / min;

[0039] Second roller: speed is 75~85m / min;

[0040] Three rollers: speed is 120-130m / min;

[0041] Four rollers: speed is 90-100m / min;

[0042] The heat setting temperature is 240-245°C;

[0043] The winding speed is 30-80 m / min.

[0044] The polyester monofilament is prepared by the relevant limited parameters of the above-mentioned conventional preparation process, and can obtain a structural feature with high crystallinity and high orientation after hot stretching and heat setting, so that the polyester monofilament has excellent mechanical properties, such as high strength (≥500MPa) and high modulus (≥5GPa). However, it is also affected by the temperature difference in the spinning process to form a skin-core structure, characterized in that the crystallinity and orientation of the inner core layer are low; the crystallinity and orientation of the cortex are too high. Because the cortex molecular chain is highly oriented along the fiber axis, and the lateral binding force between the molecular chains is low, under the action of mechanical friction external force, the fibril molecular chain in the cortex is prone to brittle fracture and split in the radial direction, which will show scum debris in the macroscopic view, affecting the fabric precision in the subsequent web forming process. Therefore, on the basis of the conventional preparation process, after the ultraviolet crosslinking post-treatment of the present invention, the cortex of the polyester monofilament is crosslinked and modified, which can effectively improve the anti-fibrillation effect of the polyester monofilament, obtain a durable and stable anti-fibrillation polyester monofilament, and still retain its excellent mechanical properties, which is also applicable to polyester monofilaments with conventional mechanical properties. It should be noted that the UV cross-linking treatment of the present invention can also be applied to conventional processes with other parameters and can improve the anti-fibrillation effect of polyester monofilaments. The present invention only preferably illustrates conventional process parameters with excellent mechanical properties, but does not constitute a limitation on the technical solution of the present invention.

[0045] Preferably, the method for preparing the anti-fibrillation polyester monofilament comprises: preparing the anti-fibrillation polyester monofilament by drying, melt extrusion, water bath cooling, oiling, hot water stretching, hot air stretching, heat setting, ultraviolet crosslinking post-treatment and winding the polyester chips, and the main spinning process parameters are as follows:

[0046] The drying temperature is 150-170°C;

[0047] The extrusion temperature is 280-300°C;

[0048] The cooling water temperature is 70-90°C;

[0049] The oil concentration of the oiling agent is 5 to 15%;

[0050] The drafting process:

[0051] One roller: speed is 20-25m / min;

[0052] Second roller: speed is 75~85m / min;

[0053] Three rollers: speed is 120-130m / min;

[0054] Four rollers: speed is 90-100m / min;

[0055] The heat setting temperature is 235-250°C;

[0056] The winding speed is 30-80 m / min.

[0057] The ultraviolet cross-linking post-treatment process comprises: immersing the prepared polyester monofilament in a mixed solution containing a cross-linking agent for reaction for 20 to 30 seconds, and then performing heat treatment and ultraviolet cross-linking treatment.

[0058] The second object of the present invention is to provide a fibrillation-resistant polyester monofilament prepared by any of the above-mentioned preparation methods. The fibrillation-resistant polyester monofilament is prepared by chemically bonding a crosslinking agent and polyester fiber, which effectively improves its fibrillation-resistant ability and does not affect the mechanical properties, thereby obtaining a stable and long-lasting fibrillation-resistant polyester monofilament with excellent mechanical properties.

[0059] Preferably, the prepared polyester monofilament has an improved degree of anti-fibrillation by ≥500%, and a mechanical property retention rate of ≥90%.

[0060] Preferably, the polyester monofilament has a diameter of 0.2 to 0.6 mm, a breaking strength of ≥500 MPa, and an elongation at break of 10 to 35%.

[0061] The present invention provides a method for preparing a polyester monofilament that is resistant to fibrillation as described above. The photocrosslinker and photoinitiator attached to the polyester monofilament rapidly act on the amorphous region of the fiber cortex under ultraviolet irradiation, and the crosslinking bonds enhance the interaction between the molecular chains. The spatial network structure formed by the crosslinking limits the mobility of the molecular chains, making it difficult for them to slip. The increase in crosslinking sites gradually limits the orderly arrangement of the straightened molecular chains in the crystal region, which can reduce the crystallinity of the polyester monofilament cortex. While reducing the brittleness of the fiber cortex, the interaction between the fibrils is enhanced, so that the ability to disperse external stress is improved, thereby achieving the effect of resisting fibrillation.

[0062] The crosslinking reaction process is that the photoinitiator simultaneously captures hydrogen from the photocrosslinking agent and polyethylene terephthalate to generate free radicals, and a crosslinking reaction occurs between the free radicals to form a crosslinking bond. Taking triallyl isocyanurate (TAIC) photocrosslinking agent and benzophenone (BP) photoinitiator as an example, the photocrosslinking mechanism is as follows: Figure 1 shown.

[0063] Compared with the prior art, the present invention achieves the following beneficial effects:

[0064] (1) The anti-fibrillation polyester monofilament prepared by the present invention has a monofilament diameter of 0.2-0.6 mm, a breaking strength of ≥500 MPa, and an elongation at break of 10-35%, and can be applied to the high-end precision printing industry.

[0065] (2) The preparation method of the anti-fibrillation polyester monofilament of the present invention adopts a method of ultraviolet crosslinking post-treatment. Compared with conventional thermal crosslinking and two-component spinning methods, it has less capital investment, is safe, simple and fast to operate, and almost does not pollute the environment. It also has little damage to the mechanical properties of the polyester monofilament, and is suitable for industrial large-scale production.

[0066] (3) The method for preparing a polyester monofilament resistant to fibrillation of the present invention improves the excessively high crystallinity of the fiber cortex and enhances the interaction force between the original fibril molecular chains by increasing the cross-linking sites, so that the polyester monofilament has excellent fibrillation resistance, which is more than 500% higher than that of the unmodified polyester monofilament, and the mechanical properties remain more than 90% of the original ones. It has broad market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 Schematic diagram of the photocrosslinking mechanism of the crosslinking reaction of the present invention. DETAILED DESCRIPTION

[0068] In order to better clarify and understand the purpose, process scheme and advantages of the present invention, the technical scheme and implementation method of the present invention are further described clearly, completely and in detail through specific examples and in combination with the accompanying drawings. It should be noted that the embodiments described in the present invention are implemented on the premise of the technical scheme of the present invention, and detailed implementation methods and specific operating processes are given, but they are only part of the embodiments of the present invention, not all of the embodiments. The specific implementation methods described are limited to explaining and interpreting the present invention, and do not limit the present invention. Based on the embodiments in the present invention, all other implementation methods obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0069] The experimental methods and conditions used in the following examples are conventional methods and conventional conditions unless otherwise specified, and the materials, reagents or instruments used in the examples, unless otherwise specified, can be obtained from commercial sources. The reaction conditions embodied in the content of the invention of the present invention can achieve the reaction and obtain the product of the expected effect. Due to space limitations, only some embodiments are listed below to further illustrate the advantages of the technical solution of the present invention.

[0070] In the embodiment of the present invention, the anti-fibrillation ability is represented by the wet friction resistance time, and the degree of improvement of the anti-fibrillation ability is represented by (D), and the calculation formula is:

[0071]

[0072] Where, t0 is the wet friction resistance time of the monofilament without cross-linking treatment; t c It is the wet friction resistance time of cross-linked monofilament.

[0073] The present invention uses a wet friction method to evaluate the fibrillation of polyester monofilaments. The wet friction method simulates the environment in which the monofilaments are prone to fibrillation based on the characteristics that the fiber is easily damaged and broken after fibrillation. The anti-fibrillation ability of the polyester monofilament is quantified by calculating the time it takes for the monofilament to be fully fibrillated to break by mechanical friction under wet conditions. The method refers to the method disclosed in the invention patent of patent publication number CN102680389A, patent application number CN201110058072.8, and patent name A method for evaluating the fibrillation performance of fibers.

[0074] The present invention uses a YG026Q fabric strength tester to evaluate the mechanical properties of polyester monofilaments. The specific test method is: the sample clamping distance is 100mm, the stretching speed is 250mm / min, each group of samples is tested five times at room temperature, and the results are averaged. The breaking strength (σ), breaking elongation (ε), and breaking strength retention (R σ ) and elongation at break retention (R ε ) and other indicators.

[0075] The breaking strength retention rate (R σ ) is calculated as:

[0076]

[0077] Where, σ0 is the breaking strength of the single filament without cross-linking treatment; σ c It is the breaking strength of the cross-linked single filament.

[0078] The elongation at break retention rate (R ε ) is calculated as:

[0079]

[0080] Where, ε0 is the elongation at break of the uncrosslinked monofilament; ε c It is the elongation at break of cross-linked monofilament.

[0081] Comparative Example

[0082] A method for preparing polyester monofilament, comprising the steps of slice drying, melt extrusion, water bath cooling, oiling, hot water stretching, hot air stretching, heat setting and winding, and the spinning process is shown in Table 1.

[0083] Table 1 Spinning process parameters of polyester monofilaments with different diameters

[0084]

[0085]

[0086] Example 1

[0087] The preparation method of 0.2 mm polyester monofilament in the comparative example is adopted, and after heat setting, ultraviolet crosslinking post-treatment is adopted, and the obtained polyester monofilament is immersed in a mixed solution containing a photocrosslinker and a photoinitiator for 20 seconds. The types of the photocrosslinker and the photoinitiator are shown in Table 2, wherein the concentration of the photocrosslinker in the mixed solution is 0.5wt%, the concentration of the photoinitiator is 0.5wt%, and the solvent of the mixed solution is ethyl acetate. The polyester monofilament with anti-fibrillation ability is prepared by heat treatment at 70°C for 5 minutes and ultraviolet crosslinking treatment at 65°C for 120 seconds. The blank sample is the polyester monofilament without crosslinking treatment in the comparative example, which is used as a comparative example to detect the effects of the types of photocrosslinkers and photoinitiators on the wet friction resistance time, the degree of improvement of anti-fibrillation ability, breaking strength and elongation at break and their retention rate of the polyester monofilament. The results are shown in Table 2:

[0088] Table 2 Summary of results of different types of photocrosslinkers and photoinitiators

[0089]

[0090]

[0091] The results show that the polyester monofilaments treated with the same steps have different anti-fibrillation abilities. Compared with the polyester monofilaments that have not been cross-linked (i.e., blank samples), the anti-fibrillation abilities of the monofilaments have been improved. Among them, benzoin dimethyl ether and chlorendic anhydride are cleavage-type photoinitiators, and the remaining photoinitiators are hydrogen-abstracting types. It can be seen that the breaking strength and elongation at break of the polyester monofilaments can be maintained at more than 80% of the blank sample after using the two types of photoinitiators. However, the anti-fibrillation effect obtained by the hydrogen-abstracting photoinitiator under the same conditions is significantly better than that of the cleavage-type photoinitiator, and the mechanical property retention rate is stable enough to be maintained at more than 90%.

[0092] Example 2

[0093] The preparation method of 0.6 mm polyester monofilament in the comparative example is adopted, and the obtained polyester monofilament is immersed in a mixed solution containing a photocrosslinker and a photoinitiator for 20 seconds, wherein the mixed solution includes a photocrosslinker of triallyl isocyanurate (TAIC) at a concentration of 0.5wt%, and a photoinitiator of a certain concentration of benzophenone (BP), the specific concentrations of which are shown in Table 3, and the polyester monofilament with anti-fibrillation ability is obtained by heat treatment at 70°C for 5 minutes and ultraviolet crosslinking treatment at a temperature of 65°C for 120 seconds. The blank sample is a polyester monofilament without crosslinking treatment, and is used as a comparative example to detect the effect of the concentration of benzophenone (BP) photoinitiator on the fibrillation index, the degree of improvement of anti-fibrillation ability, breaking strength, elongation at break and its retention rate of the polyester monofilament, and the results are shown in Table 3:

[0094] Table 3 Concentration changes of benzophenone (BP) photoinitiator and summary of results

[0095]

[0096] The results show that when the benzophenone photoinitiator content is lower than 0.25wt%, the mechanical properties are almost not damaged, but its anti-fibrillation ability is poor. Although the anti-fibrillation ability has been improved, if the polyester monofilament is used for high-precision printing screens, this index is still difficult to meet the application requirements. With the increase of the concentration of benzophenone photoinitiator, the anti-fibrillation ability is significantly improved, especially between 0.25 and 1.0wt%, its anti-fibrillation ability can be increased by more than 500%, and the mechanical properties are also maintained well, all above 90% of the blank sample. When the concentration of benzophenone photoinitiator is higher than 1.0wt%, the anti-fibrillation ability and mechanical properties of polyester monofilament begin to decline significantly. In summary, the anti-fibrillation effect of benzophenone photoinitiator concentration is better at 0.25-1.0wt%, and the mechanical properties are also maintained well, among which 0.5wt% is the best.

[0097] Example 3

[0098] The preparation method of 0.6 mm polyester monofilament in the comparative example was adopted, and the obtained polyester monofilament was immersed in a mixed solution containing a photocrosslinker and a photoinitiator for 20 seconds, wherein the photocrosslinker was a certain concentration of triallyl isocyanurate, and the specific concentration was shown in Table 4, and the photoinitiator was 0.5wt% of benzophenone, and the polyester monofilament with anti-fibrillation ability was obtained by heat treatment at 70°C for 5 minutes and ultraviolet crosslinking treatment at 65°C for 120 seconds. The blank sample was a polyester monofilament without crosslinking treatment, and was used as a comparative example to detect the effect of the concentration of the photocrosslinker on the wet friction resistance time, the degree of improvement of the anti-fibrillation ability, the breaking strength, the breaking elongation and its retention rate of the polyester monofilament, and the results are shown in Table 4:

[0099] Table 4 Concentration changes and result summary of triallyl isocyanurate photocrosslinker

[0100]

[0101]

[0102] The results show that the use of triallyl isocyanurate photocrosslinker can significantly improve the antigenicity of polyester monofilaments. When the concentration of triallyl isocyanurate photocrosslinker is less than 0.5wt%, as the concentration of crosslinker increases, its anti-fibrillation ability can be increased by 452.5% on the basis of the blank sample, and the mechanical properties are almost not negatively affected. However, if the polyester monofilament is used for high-precision printing screens, this index is still difficult to meet the application requirements. As the concentration of triallyl isocyanurate photocrosslinker continues to increase, the anti-fibrillation ability of polyester monofilaments is significantly improved, especially between 0.5 and 5.0wt%, its anti-fibrillation ability can be stably increased by more than 500%. However, when the concentration of crosslinker exceeds 2.0wt%, the breaking strength and elongation of polyester monofilaments are significantly reduced, and the retention rate is less than 90%, which is difficult to meet the application requirements. In summary, the anti-fibrillation ability of triallyl isocyanurate photocrosslinker with a concentration between 0.5 and 2.0wt% is good, and the mechanical properties are also maintained above 90%, among which 0.5wt% is the best.

[0103] Example 4

[0104] The preparation method of 0.2 mm polyester monofilament in Example 1 was adopted, and the heat treatment conditions were changed. The prepared polyester monofilament was immersed in a mixed solution containing a photocrosslinker and a photoinitiator for 20 seconds, wherein the photocrosslinker was 0.5 wt% triallyl isocyanurate and the photoinitiator was 0.5 wt% benzophenone, and heat-treated under different conditions. The specific conditions are shown in Table 5. The ultraviolet crosslinking treatment was carried out at a temperature of 65°C for 120 seconds to obtain a polyester monofilament with anti-fibrillation ability. The blank sample is a polyester monofilament that has not been crosslinked. As a comparative example, the influence of heat treatment temperature and time on the wet friction resistance time, the degree of improvement of anti-fibrillation ability, breaking strength, elongation at break and its retention rate of the polyester monofilament are detected. The results are shown in Table 5:

[0105] Table 5 Summary of heat treatment conditions and results

[0106]

[0107]

[0108] The results show that when the heat treatment temperature is lower than 70℃, the anti-fibrillation ability of polyester monofilament is not significantly improved based on the anti-fibrillation ability of the blank sample, and the mechanical properties are significantly affected due to the uneven crosslinking. As the heat treatment temperature increases, the anti-fibrillation ability increases, but when the temperature exceeds 90℃, the anti-fibrillation ability and mechanical properties may decrease significantly. In addition, under the same heat treatment temperature, the anti-fibrillation ability of polyester monofilament increases with the increase of heat treatment time. It is difficult to ensure that the anti-fibrillation ability reaches the expected effect before 5 minutes of heat treatment, while the anti-fibrillation of the sample is basically stable after 10 minutes of heat treatment. Considering that increasing the heat treatment time will not only increase the cost, but also affect the mechanical properties of the fiber. Therefore, combined with the above experimental data, considering factors such as cost, the heat treatment temperature is controlled between 70 and 90℃ to ensure good anti-fibrillation ability, and the heat treatment time is controlled between 5 and 10 minutes, the comprehensive performance of the fiber is the best.

[0109] Example 5

[0110] The preparation method of 0.2 mm polyester monofilament in Example 1 was adopted, and the ultraviolet crosslinking time was changed. The prepared polyester monofilament was immersed in a mixed solution containing a photocrosslinker and a photoinitiator for 20 seconds, wherein the photocrosslinker was 0.5 wt% triallyl isocyanurate and the photoinitiator was 0.5 wt% benzophenone, and heat treated at 70°C for 5 minutes, and ultraviolet crosslinking treatment was carried out at 65°C for a certain time, as shown in Table 6, to obtain polyester monofilament with anti-fibrillation ability. The blank sample is a polyester monofilament that has not been crosslinked. As a comparative example, the influence of heat treatment temperature and time on the wet friction resistance time, the degree of improvement of anti-fibrillation ability, breaking strength and breaking elongation of the polyester monofilament are detected. The results are shown in Table 6:

[0111] Table 6 UV cross-linking conditions and results summary

[0112]

[0113]

[0114] The results show that under certain conditions, the longer the UV crosslinking time, the stronger the anti-fibrillation ability of polyester monofilament. When the UV crosslinking time is 150s, the anti-fibrillation ability of the fiber is increased by 918.9% compared with the blank sample, and the mechanical properties can also be maintained above 90%. After that, the anti-fibrillation ability of the fiber does not change significantly when the UV crosslinking time is increased, and the breaking strength and elongation at break decrease significantly. In addition, the above data show that under the condition of UV crosslinking time of 150s, with the increase of UV crosslinking temperature, the anti-fibrillation ability of the fiber increases, while the mechanical properties show a downward trend. When the UV crosslinking temperature is 65℃, the anti-fibrillation ability is increased by 918.9% compared with the blank sample, and then the anti-fibrillation ability and mechanical properties decrease significantly with the increase of temperature. In summary, the UV crosslinking time of 120-150s and the UV crosslinking temperature of 55-65℃ have good anti-fibrillation effect and can have excellent mechanical properties.

[0115] The above-described embodiments are only preferred solutions of the present invention and are not intended to limit the present invention in any form. Other variations and modifications are possible without exceeding the technical solutions described in the claims.

Claims

1. A method for preparing a fibrillation-resistant polyester monofilament, characterized in that: The preparation method comprises: preparing polyester monofilaments; and ultraviolet cross-linking post-treatment.

2. The method for preparing a fibrillation-resistant polyester monofilament according to claim 1, characterized in that: The UV cross-linking post-treatment comprises the following steps: (1) immersing the prepared polyester monofilament in a solution containing a cross-linking agent; (2) heat treating the impregnated polyester monofilament; (3) The polyester monofilament after heat treatment is subjected to a UV cross-linking step to complete the UV cross-linking post-treatment.

3. The method for preparing a fibrillation-resistant polyester monofilament according to claim 2, characterized in that: In the solution containing the crosslinking agent in step (1), the concentration of the crosslinking agent is 0.5-2 wt %, and the crosslinking agent is selected from at least one of triallyl isocyanurate, triallyl cyanurate, pentaerythritol triallyl propionate, and glycidyl methacrylate.

4. The method for preparing a fibrillation-resistant polyester monofilament according to claim 2, characterized in that: The solution containing the crosslinking agent in step (1) also contains a photoinitiator. The concentration of the photoinitiator in the solution is 0.25-1 wt %. The photoinitiator is a hydrogen abstraction type initiator.

5. The method for preparing a fibrillation-resistant polyester monofilament according to claim 2, characterized in that: In the step (1), the mixture is immersed for 20 to 30 seconds.

6. The method for preparing a fibrillation-resistant polyester monofilament according to claim 2, characterized in that: The heat treatment in step (2) is performed at a temperature of 70 to 90° C. and for a time of not less than 5 minutes.

7. The method for preparing a fibrillation-resistant polyester monofilament according to claim 2, characterized in that: In the ultraviolet cross-linking step in step (3), the peak value of the ultraviolet light is 280-400nm, the ultraviolet cross-linking temperature is 55-65°C, and the ultraviolet cross-linking time is 120-150s.

8. The method for preparing a fibrillation-resistant polyester monofilament according to claim 1, characterized in that: The preparation process of the polyester monofilament without UV crosslinking treatment includes the steps of polyester chip drying, melt extrusion, water bath cooling, oiling, and drawing. The main process parameters are as follows: The drying temperature is 150-170°C; The extrusion temperature is 280-300°C; The cooling water temperature is 70-80°C; The oil concentration of the oiling agent is 5 to 15%; The drafting process: One roller: speed is 20-25m / min; Second roller: speed is 75~85m / min; Three rollers: speed is 120-130m / min; Four rollers: speed is 90-100m / min; The heat setting temperature is 240-245°C.

9. A fibrillation-resistant polyester monofilament prepared by the preparation method according to any one of claims 1 to 8.

10. The anti-fibrillation polyester monofilament according to claim 9, characterized in that: The anti-fibrillation ability of the prepared polyester monofilament is improved by ≥500%, the mechanical property retention rate is ≥90%, the diameter of the polyester monofilament is 0.2-0.6mm, the breaking strength is ≥500MPa, and the breaking elongation is 10-35%.

Images