Chemically sharpened co-extruded polyester monofilament as a substitute for animal hair

Abstract

A kind of ground filament of co-extrusion monofilament with skin-core structure, wherein the core layer includes polybutylene terephthalate PBT and optional additives, the skin layer includes polytrimethylene terephthalate PTT or polybutylene terephthalate PBT and optional additives, at least one end of the co-extrusion monofilament with skin-core structure is chemically treated to be ground, characterized in that wherein the ground filament includes tip region, middle region and rear end region in turn from its tip, wherein the tip region, middle region and rear end region are rough surfaces with different roughness levels;And, tip region length is ≥4mm, middle region length is 4-50mm.

Description

Technical Field

[0001] This invention generally relates to artificial animal hair. More specifically, this invention relates to co-extruded polyester monofilaments that replace animal hair and combine good feed capacity and tactile feel with chemically refined materials. Background Technology

[0002] In recent years, the proportion of brush filaments made from synthetic polymers in the market for brushes mimicking natural animal hair has been gradually increasing. Compared with natural animal hair, chemically sharpened synthetic polymer monofilaments have a cost advantage, but they are difficult to imitate the unique scaly structure of the surface of natural animal hair. This limits their ability to pick up and release loose powder, ink, and paint when used as makeup brushes, calligraphy brushes, and paintbrushes. To improve the brush's material-carrying capacity, inorganic fillers can be added to the bristles to increase the surface roughness of the monofilaments. However, because inorganic fillers are uniformly distributed in the bristles, the rough structure that appears on the surface of the bristles after chemical sharpening lacks regional differences. This causes the tips of the finished bristles to become short and blunt, affecting the feel of the brush.

[0003] Monofilaments can be produced through conventional extrusion processes. The most common extruded monofilaments are those with a uniform diameter. The ends of these monofilaments are then sharpened to obtain sharpened monofilaments, hereinafter also referred to as "sharpened monofilaments" or "sharpened filaments".

[0004] The tapered filament market is an important sub-market, and its preparation typically involves both mechanical and chemical tapering of ordinary extruded monofilaments. Currently, the share of chemically tapered polyester monofilaments is gradually increasing.

[0005] US Patent 6090488 discloses a tapered brush bristle made of polybutylene terephthalate (PBT) or polyethylene terephthalate (PET). In the method disclosed in this patent, the tapered bristles are manufactured by first cutting PBT or PET bristles to a certain length, then vertically immersing them in a strong alkali or acid solution to a depth of 10 mm, etching them to form a tapered end with a diameter of 0.10 mm-0.15 mm. The bristles are then washed and dried, and subsequently installed into a toothbrush head. Optionally, the bristle ends are trimmed and rounded. This patent requires mechanical rounding of the bristle ends after they are installed on the brush head.

[0006] JP-2001-169829 discloses a toothbrush bristle made of polyester monofilament with different cross-sectional shapes and predetermined lengths. In the bristle manufacturing method of this patent, the cut bristles are first packaged using a paper wrapping method, and then the fiber axis is perpendicular to the bottom of a stainless steel container. Next, the end of the packaged bristle bundle is immersed in a 40wt% sodium hydroxide solution at 110°C for a certain period of time. Then, the other end of the bristle bundle is treated with alkali in the same way. Finally, it is washed with water and dried to obtain toothbrush bristles with tapered ends.

[0007] Polyesters are typically used to prepare the tapered filaments, or monofilaments with tapered ends. These polyesters include, but are not limited to, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polypropylene terephthalate (PTT).

[0008] JP2003169718A discloses a monofilament and a toothbrush using the monofilament, specifically disclosing that the monofilament is configured as a double-core structure consisting of a first resin layer and a second resin layer, and that the tip portion of the monofilament in the double-core structure can be formed into a tapered shape. Further details of the monofilament tip of the double-core structure are not disclosed, nor are any effects on improving material carrying capacity and tactile feel disclosed.

[0009] There is still a sustained market demand for co-extruded polyester monofilaments with good material handling capacity and tactile feel.

[0010] Unexpectedly, the inventors discovered that in the co-extruded polyester filaments coated with silicone oil after chemical grinding prepared according to the present invention, by specifically controlling the ratio of the sheath thickness to the diameter of the co-extruded polyester monofilament within a certain range, and further controlling the surface morphology distribution of the co-extruded filaments, i.e. forming a shape that sequentially includes a tip region, a middle region, and a rear end region starting from the tip of the filament, wherein the tip region, middle region, and rear end region are rough surfaces with different degrees of roughness, a co-extruded polyester filament with good material carrying capacity and tactile feel for use in the chemical grinding of artificial animal hair can be obtained. In the grasping and releasing experiments of ink, powder, and paint, compared with the filament without the co-extruded structure, the grasping and releasing amount of such materials as ink is significantly improved, and the release length is also significantly increased. Summary of the Invention

[0011] This invention provides a sharpened filament of a co-extruded monofilament coated with silicone oil and having a core-sheath structure, wherein at least one end of the co-extruded monofilament with the core-sheath structure is chemically treated and sharpened to obtain the sharpened filament. The sharpened filament is characterized by comprising, from its tip, a pointed region, a middle region, and a rear region, wherein the pointed region, middle region, and rear region are rough surfaces with different degrees of roughness; and the length of the pointed region is ≥4 mm, and the length of the middle region is 4-50 mm, preferably 4-30 mm, and more preferably 4-20 mm.

[0012] In one embodiment of the invention, the diameter of the abrasive filament is 0.05-0.5 mm, preferably 0.05-0.3 mm, more preferably 0.05-0.18 mm; and the ratio of the skin thickness of the abrasive filament to the diameter of the abrasive filament is 5-30%, preferably 10-20%.

[0013] In another embodiment of the invention, the diameter of the tapered filament at a distance of 0.01 mm from the tip is ≤0.05 mm, preferably ≤0.01 mm.

[0014] In a further preferred embodiment of the invention, the rough surface of the tip region has a pitted morphology, and the average area of ​​the pits in the tip region is ≤10 μm. 2 The rough surface at the beginning of the central region contains pores, and the average area of ​​the pores in the beginning region of the central region is >10 μm. 2 The pore area gradually decreases from the beginning to the end of the middle region, and the average pore area at the end of the middle region is >3μm. 2 The relatively smooth surface of the rear end region contains tiny pores, and the average area of ​​the pores in the rear end region is ≤3μm. 2 Preferably ≤2μm 2 .

[0015] In a more preferred embodiment of the invention, the core layer of the core-skin structure comprises polybutylene terephthalate (PBT) and optionally present additives, and the skin layer of the core-skin structure comprises polybutylene terephthalate (PTT) or polybutylene terephthalate (PBT) and optionally present additives. Particularly preferably, the core layer of the core-skin structure is composed of polybutylene terephthalate (PBT) and optionally present additives; the skin layer of the core-skin structure is composed of polybutylene terephthalate (PTT) or polybutylene terephthalate (PBT) and optionally present additives.

[0016] This invention also provides a method for preparing the chemically sharpened co-extruded polyester filament. First, a core-sheath structure monofilament is prepared by co-extrusion spinning, primarily with PBT as the core layer and PTT as the sheath layer. The sheath thickness can be precisely adjusted by changing the pump speed. Then, the core-sheath structure monofilament obtained in the previous step is cut into filament cakes and immersed in a strong acid and / or strong alkali solution of a certain concentration to a certain depth and for a certain period of time, so that at least one end is sharpened. Finally, the chemically sharpened co-extruded polyester monofilament is coated with silicone oil.

[0017] The present invention also provides brush bristles made from the above-described tapered filaments, brush filaments made from the brush bristles that mimic animal hair, and paintbrushes, cosmetic brushes, and paintbrushes containing the brush filaments. Attached Figure Description

[0018] Figure 1 The image shown is a SEM photograph of the pit at the end of the tip region of sample 1 according to the present invention.

[0019] Figure 2 The image shown is a SEM photograph of the holes at the beginning of the middle region of sample 1 according to the present invention;

[0020] Figure 3 The image shown is a SEM photograph of the holes at the end of the middle region of sample 1 according to the present invention;

[0021] Figure 4 The image shown is a SEM image of the micropores at the beginning of the rear end region of sample 1 according to the present invention. Invention Details

[0023] Except as provided in the examples or otherwise expressly indicated, all figures in this specification representing the amount of material or reaction conditions, the physical properties of the material and / or its use may optionally be understood to be modified by the word “about”.

[0024] Unless otherwise stated, all quantities are by weight of the composition.

[0025] It should be noted that when specifying any numerical range, any particular upper limit value can be associated with any particular lower limit value.

[0026] To avoid ambiguity, the word "contains" is intended to mean "including," but not necessarily "composed of" or "consisting of." In other words, the steps or options listed do not need to be exhaustive.

[0027] The disclosure of the present invention found herein is intended to cover all embodiments found to be multiplely dependent on each other in the claims, regardless of the fact that the claims may not be found to be multiplely dependent or redundant.

[0028] Where a feature is disclosed with respect to a particular aspect of the invention (e.g., the composition of the invention), such disclosure is also considered applicable to any other aspect of the invention (e.g., the method of the invention) with necessary modifications.

[0029] Monofilament base resin

[0030] The base resin for the monofilaments used in this invention can be polyester resin.

[0031] The polyesters applicable to this invention are typically formed by condensation polymerization of dicarboxylic acids and diols.

[0032] Resin for the core layer

[0033] In the co-extruded polyester filament with good material carrying capacity and tactile feel provided by the present invention, the polyester resin used as the core layer can be polybutylene terephthalate resin.

[0034] Polybutylene terephthalate resin, abbreviated as PBT resin, is typically obtained through the condensation polymerization of terephthalic acid and 1,4-butanediol. Specifically, PBT is usually obtained through direct esterification or transesterification.

[0035] PBT resin is commonly used as an engineering plastic, spinning material, etc.

[0036] In embodiments of the present invention, exemplary representatives of the PBT resin used include PBTB2520 purchased from BASF, PBT L2100 purchased from Sinopec Yizheng Chemical Fiber, PBT 1200 211D / 211M purchased from Changchun Chemical, and spinning-grade PBT purchased from Hengli Chemical Fiber.

[0037] Most preferably, in an embodiment of the present invention, the PBT resin used is PBT L2100 purchased from Sinopec Yizheng Chemical Fiber.

[0038] Resins for the skin

[0039] In the co-extruded polyester filament with good material carrying capacity and tactile feel provided by the present invention, the polyester resin suitable as the skin layer can be polypropylene terephthalate resin.

[0040] Poly(propylene terephthalate) resin, abbreviated as PTT resin, is a relatively new polyester material. It is produced by the condensation polymerization reaction of terephthalic acid (PTA) and 1,3-propanediol (PDO).

[0041] Industrialized PTT is one of the latest industrialized polyester products, mainly developing after the efficient production of its raw material 1,3-propanediol was achieved.

[0042] Polypropylene terephthalate (PTT) resin combines the performance advantages of various materials and is one of the latest and most popular new polymer materials developed internationally. It can be widely used in multiple fields such as fiber materials and engineering plastics.

[0043] In embodiments of the present invention, exemplary representatives of the PTT resin used include commercially available PTT resins from DuPont China Group Limited, such as those marketed under trademarks. PTT resin obtained from K1141.

[0044] The polyester resin suitable as the skin layer can also be polybutylene terephthalate resin PBT, which can be extruded together with commonly used fillers in the art such as calcium carbonate, barium sulfate, talc, glass fiber, and mica to serve as the skin layer of the co-extruded monofilament in this application.

[0045] silicone oil

[0046] In an embodiment of the present invention, the surface of the co-extruded polyester filament for chemical grinding needs to be coated with silicone oil.

[0047] Silicone oil typically refers to linear polysiloxane products that remain liquid at room temperature, and usually has the following structural formula:

[0048]

[0049] Wherein, R is alkyl or aryl, R' is alkyl, aryl, hydrogen, carbon functional group, amino-containing alkyl and polyether chain, etc.; X is alkyl, aryl, alkenyl, hydrogen, hydroxyl, alkoxy, acetoxy, chlorine, carbon functional group and polyether chain, etc.; n, m = 0, 1, 2, 3, etc.

[0050] According to the present invention, in the structure shown above, when all organic groups are methyl, the silicone oil is called methyl silicone oil. Other organic groups can also be used to replace some of the methyl groups to improve certain properties of the silicone oil and make it suitable for various applications. Common other groups include hydrogen, ethyl, phenyl, chlorophenyl, trifluoropropyl, etc.

[0051] In embodiments of the invention, the silicone oil can typically be used in the form of an emulsion; that is, a silicone oil emulsion can be used in the invention. In a preferred embodiment of the invention, the silicone oil emulsion is typically diluted with water and then coated onto the surface of the monofilament.

[0052] In embodiments of the present invention, exemplary examples of silicone oils that can be used in the present invention include: DOWSIL from Dow Inc. TM SH 7024, DOWSIL TM8024, DOWSIL TM MEM 0024; ElkemSILCOLAPSE from Elkem Silicones TM 7140; Momentive SM2128 from Momentive Performance Materials Inc.; from Wacker Chemie International Group, Germany. FC 228E, etc.

[0053] Other additives

[0054] In the polyester monofilament of the present invention, other additives may be added as needed, including but not limited to antioxidants, light stabilizers, antistatic agents, lubricants, plasticizers, fillers, antibacterial agents, etc.

[0055] In this invention, the antioxidant can be any antioxidant commonly used in the art. In a preferred embodiment of this invention, the antioxidant is selected from butylated hydroxytoluene (BHT), phenyl-β-naphthylamine, alkyl-p-quinone, thioether, phenyl salicylate, mercaptothioether, thiopropionate, hindered phenol, etc.

[0056] In this invention, the antistatic agent can be any antistatic agent commonly used in the art. In a preferred embodiment of this invention, the antistatic agent is selected from quaternary ammonium salts, ethoxylated amines, sulfonated paraffins, and combinations thereof.

[0057] In this invention, the lubricant can be any lubricant commonly used in the art. In a preferred embodiment of the invention, the lubricant is selected from aliphatic esters (e.g., monoglycerides of fatty acids) and combinations thereof.

[0058] In this invention, the plasticizer can be any plasticizer commonly used in the art. In a preferred embodiment of this invention, the plasticizer is selected from terephthalates, phthalates, aliphatic diesters, phosphate esters, chlorinated paraffins, and combinations thereof.

[0059] In this invention, the filler can be any filler commonly used in the art, including but not limited to calcium carbonate, glass fiber, glass sheet, aluminum sheet, glass beads, carbon fiber, talc, mica, wollastonite, calcined clay, kaolin, diatomaceous earth, sodium fluoride, magnesium sulfate, magnesium silicate, barium sulfate, titanium dioxide, sodium aluminum carbonate, potassium titanate, and mixtures thereof.

[0060] Method for preparing co-extruded monofilaments with skin-core structure

[0061] In this invention, monofilaments with a skin-core structure can be prepared using methods conventional in the art. These include, but are not limited to, melt co-extrusion methods. Specifically, in one embodiment of this invention, a method for preparing the co-extruded monofilament is provided, comprising the following steps:

[0062] 1) The core layer composition B containing PBT resin is added to extruder B, and the skin layer composition A containing PTT resin is added to extruder A, and the skin layer composition A and the core layer composition B are melted respectively.

[0063] 2) The melt of the skin layer composition A enters the skin layer material channel in the extrusion spinneret assembly, and the melt of the core layer composition B enters the core layer material channel in the extrusion spinneret assembly. The two melts then merge in the extrusion spinneret assembly and are extruded from the spinneret holes on the spinneret plate. The composite melt of the skin layer composition and the core layer composition is then drawn into cold water for rapid cooling and solidification, and subsequently stretched several times in hot water.

[0064] 3) Adjust the skin thickness by adjusting the pump speed of extruder A and extruder B.

[0065] 4) After being shaped in a dry heat oven, it is finally rolled up and packaged.

[0066] This yields co-extruded monofilaments with PBT core / PTT sheaths of varying sheath thicknesses, featuring a sheath-core structure.

[0067] Chemical sharpening

[0068] The chemical sharpening method involves cutting a monofilament rod with a specific sheath thickness and a specific ratio of sheath thickness to monofilament diameter, obtained in a previous step, into a filament cake, and then immersing it in a strong acid and / or strong alkali solution of a certain concentration to a certain depth and for a certain period of time, so that at least one end of the monofilament is chemically sharpened.

[0069] The chemical sharpening process can involve chemically sharpening one end of the monofilament or both ends of the monofilament. In one embodiment of the invention, only one end of the monofilament is chemically sharpened. In another embodiment of the invention, both ends of the monofilament are chemically sharpened.

[0070] Specifically: the monofilament cake with a core-sheath structure according to the present invention is immersed face down in a strong alkaline solution of a certain concentration to a certain depth and for a certain period of time, and / or the monofilament cake with a core-sheath structure according to the present invention is placed horizontally and completely immersed in the alkaline solution for a certain period of time.

[0071] In one aspect of the invention, the strong alkaline solution may be a sodium hydroxide solution, a potassium hydroxide solution, or a combination thereof.

[0072] In another aspect of the invention, the time for immersing the monofilament with a core-sheath structure obtained by the invention in the strong alkaline solution can be from 30 min to 300 min; for example, from 60 min to 240 min, or most preferably from 120 min to 210 min.

[0073] Silicone oil coating on the surface of chemically sharpened monofilaments

[0074] In a specific embodiment of the present invention, after the chemical grinding of the monofilaments is completed, the filament cake is thoroughly cleaned and dried, and then a silicone oil coating liquid is sprayed on. Specifically, a thin film of silicone oil emulsion is uniformly coated on the surface of the ground filaments, so that the silicone oil emulsion can penetrate into the ground filaments, but most of the silicone oil emulsion remains on the surface of the ground filaments. This makes it easier to arrange the ground filaments and obtain a neatly arranged filament cake. The amount of silicone oil coated on the ground filaments must be appropriate. Too much silicone oil will cause the ground filaments to stick together, making them difficult to straighten during brush making; too little oil will cause the filament bundle to dry out, also making it difficult to straighten the pointed filaments during brush making.

[0075] Surface morphology of sharpened wire

[0076] According to an embodiment of the present invention, after the chemical sharpening process, the surface of the co-extruded sharpened filament forms three different morphological characteristics or roughness levels starting from its tip, specifically, in order, the tip region, the middle region, and the rear region. When both ends of the co-extruded monofilament are chemically sharpened, both ends respectively possess the three different morphological characteristics or roughness levels described above.

[0077] The surface of the tip region is a rough surface with a pitted morphology. The pits are very shallow depressions, typically less than 0.5 μm deep, and the average area of ​​the pits in the tip region is ≤10 μm². 2 The filament diameter at 0.01 mm from the tip of the abrasive filament is typically ≤0.05 mm, preferably ≤0.01 mm. In embodiments of the present invention, because PBT is used as the core, it is easier to achieve a fine tip region than PTT or PBT containing inorganic fillers, thereby ensuring a good tactile feel when used as a brush.

[0078] According to an embodiment of the present invention, the tip length should generally not be too short, otherwise it will affect the tactile feel of the brush. According to one embodiment of the present invention, the tip length needs to be controlled to be ≥4mm. In actual production, there is no particular upper limit to the tip length, but it can generally be <20mm.

[0079] The central region follows the tip region. In an embodiment according to the invention, the central region has the roughest surface, consisting of numerous pores that are deeper than pits, typically at least >0.5 μm deep. The average area of ​​the pores in the initial region of the central region is >10 μm². 2The pore area gradually decreases from the beginning to the end of the middle region, and the average pore area at the end of the middle region is >3μm. 2 .

[0080] In an embodiment of the invention, the length of the central region is 4-50 mm, more preferably 4-30 mm, and most preferably 4-20 mm.

[0081] Following the middle section of the bristles is the rear section, where the surface is neither too rough nor mostly smooth; even if it is rough, the average area of ​​the micropores on its surface is ≤3μm. 2 Preferably, the average area of ​​the pores on its surface is ≤2μm. 2 This ensures the ease of brush preparation during the brush-making process.

[0082] By creating a co-extruded polyester monofilament surface with a typically uniquely arranged rough morphology, the gripping and release capabilities of the co-extruded pointed filament for powder, ink, and paint can be significantly improved. For example, compared to ordinary PBT pointed filament, PTT / PBT co-extruded pointed filament exhibits a 54% increase in ink gripping, a 60% increase in release, and a 97% extension in ink release length. PTT / PBT co-extruded pointed filament also shows a significant improvement in its ability to carry powder and paint.

[0083] The present invention will be described in more detail below with reference to the embodiments. The embodiments of the present invention are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of the present invention.

[0084] Those skilled in the art can improve and adjust the technical solution without departing from the spirit of the present invention, and the specific protection scope of the present invention will be defined by the appended claims. Detailed Implementation

[0085] Basic raw material description

[0086] Polybutylene terephthalate (PBT): Commercially available polybutylene terephthalate (PBT) was purchased from Sinopec Yizheng Chemical Fiber Co., Ltd. (PBT L2100).

[0087] Polypropylene terephthalate (PTT): Produced using DuPont China Group Co., Ltd. K1141.

[0088] Silicone oil: food-grade polydimethylsiloxane aqueous emulsion; specifically, DOWSIL purchased from Dow Inc. TM SH 7024.

[0089] Ink: Commercially available ink is used, specifically Yidege premium ink.

[0090] Pressed powder: Commercially available pressed powder is used, specifically the Jingda Marshmallow Oil Control Pressed Powder.

[0091] Xuan paper: Commercially available Xuan paper is used, specifically Yidege calligraphy and painting Xuan paper (semi-sized).

[0092] TPU film: Commercially available TPU film is used, specifically a 0.5mm thick frosted film.

[0093] Test method description

[0094] 1. Test method for the ratio of monofilament skin thickness to monofilament diameter

[0095] 1.1 Using a laser diameter gauge with an accuracy of 0.01 mm, the diameter of the single filament is measured at the middle of the filament. The diameters of 150 single filaments are measured to obtain the average single filament diameter.

[0096] 1.2 Using a slicer, cut a flat end face in the middle of the monofilament and then observe it under a microscope. Using the microscope's measurement function, measure the cortical thickness of at least 15 monofilaments and take the average value to obtain the average cortical thickness of the monofilament.

[0097] 1.3. Calculate the ratio (%) of cortex thickness to monofilament diameter according to the following formula.

[0098]

[0099] In the context of this application, the monofilament sheath thickness and monofilament diameter described in the above test methods have the same meaning as the tapered filament sheath thickness and tapered filament diameter described in this application, and can be used interchangeably; that is, the tapered filament sheath thickness and tapered filament diameter both refer to the sheath thickness and overall diameter of the co-extruded monofilament in the un-chemically tapered part of the tapered filament.

[0100] 2. Method for testing the diameter from the tip of the grinding wire

[0101] Examine the filament at a distance of 0.01 mm from the tip of the ground wire using a microscope with a magnification of 30x or higher. The minimum graduation of the microscope is 0.001 mm. Measure the diameter of the monofilament at a distance of 0.01 mm from the tip of the ground wire.

[0102] For each sample, 30 grinding wires were randomly selected and the above test was repeated. The diameter of the single wire at 0.01 mm from the tip of the wire was counted among the 30 measured grinding wires.

[0103] 3. Measurement of the dimensions of each section of the pointed wire

[0104] The lengths of each segment of the sharpened wire were measured using scanning electron microscopy (SEM), with units in mm. The wire sample was fixed on the sample stage, and gold sputtering was performed at 20 mA for 60 s using a JEOL EC-30000BU. The surface morphology of the sample was then observed using a JEOL IT200 SEM at 10 kV. The lengths of each segment were measured and recorded, with at least three parallel measurements taken for each sample, and the average value was calculated.

[0105] 4. Measurement of the roughness (diaphragm or hole size) of each zone of the sharpened wire.

[0106] The surface morphology of each location of the monofilament was observed using a scanning electron microscope. The length and width of five pits or holes were measured using the measurement function. Data from at least two filaments were collected. The area of ​​each pit or hole was calculated and the average value was taken.

[0107] 5. Measurement of ink gripping amount, ink dispensing amount, and ink dispensing length.

[0108] 5.1 The invention sample and the control sample with the same filament diameter were made into small brushes with a bristle length of 25mm. The number of bristles in the small brushes was made as close as possible by weighing.

[0109] 5.2 Pour the ink into the ink tray, weigh the initial weight of the small brush, move it back and forth three times in the diameter direction of the ink tray, and weigh it again. This weight is the weight after the brush has gripped the ink.

[0110] Ink-grabbing amount = weight after ink-grabbing - initial weight.

[0111] 5.3 Lay the Xuan paper flat, and use a small brush to stroke from the left end to the right end, and then from the right end to the left end. This is counted as one stroke of ink. Repeat this process 3 times, and then weigh the small brush. This is recorded as the weight after ink application.

[0112] Ink dispensing volume = weight after ink grabbing - weight after ink dispensing.

[0113] 5.4 Measure and record the ink dispensing length using a ruler. The ink dispensing endpoint is the point where the width of the white part (i.e. the part without ink) in the vertical direction of ink dispensing just reaches 2mm.

[0114] 5.5 Repeat steps 5.2 and 5.3 to obtain the ink grabbing amount, ink dispensing amount, and ink dispensing length for the second and third uses of the brush. Each sample should have at least 5 parallel samples. The average of the 5 parallel data for the third use of each sample should be taken as the representative data for ink grabbing amount, ink dispensing amount, and ink dispensing length.

[0115] 6. Measurement of powder grabbing and powder dispensing amounts

[0116] The basic operation is the same as in step 5, except that you replace the ink with powder and the rice paper with TPU film.

[0117] Preparation Examples

[0118] Description of co-extruded monofilament preparation

[0119] 1) The core layer composition B containing PBT resin is added to extruder B, and the skin layer composition A containing PTT resin is added to extruder A, and the skin layer composition A and the core layer composition B are melted respectively.

[0120] 2) The melt of skin composition A enters the skin material channel in the extrusion spinneret assembly, and the melt of core composition B enters the core material channel in the extrusion spinneret assembly. The two melts are then combined in the extrusion spinneret assembly. After extrusion from the spinneret orifices on the spinneret, the composite melt of the skin and core compositions is drawn into cold water for rapid cooling and solidification, followed by stretching several times in hot water. The skin thickness is adjusted by adjusting the pump speeds of extruders A and B.

[0121] 3) After being shaped in a dry heat oven, it is finally rolled up and packaged.

[0122] This yields a monofilament rod with a skin-core structure consisting of a PBT core and a PTT skin.

[0123] Chemical sharpening treatment

[0124] The chemical tipping method involves cutting a previously prepared monofilament rod with a skin-core structure into a filament cake and immersing one end in a 40 wt.% sodium hydroxide aqueous solution heated to 110°C for 180 min. The tip morphology is controlled by adjusting the concentration and temperature of the alkali solution and the immersion time.

[0125] Silicone oil coating

[0126] After chemically sharpening the monofilaments, the filament cake is thoroughly cleaned, coated with a silicone oil solution, and then dehydrated and dried. Finally, the filament cake is trimmed and repackaged.

[0127] Examples 1-3

[0128] Based on the above preparation examples, monofilaments with different sheath thicknesses were prepared under the fixed condition of a monofilament diameter of 0.102 mm; the ratio of sheath thickness to monofilament diameter is referred to as "sheath thickness / filament diameter (%)" in the following table.

[0129] Example 1 (Invention): PTT / PBT co-extruded pointed filament with a skin thickness to monofilament diameter ratio of 19%, corresponding to sample 1;

[0130] Example 2 (Invention): PTT / PBT co-extruded pointed filament with a skin thickness to monofilament diameter ratio of 11%, corresponding to sample 2;

[0131] Example 3 (not of this invention): Conventional ordinary PBT tapered wire, without core-sheath structure, corresponding to sample 3;

[0132] Table 1: Length of each zone and tip diameter of the grinding wire in this application

[0133]

[0134] Note: Because sample 3 has no core-sheath structure, there is no data on sheath thickness / fiber diameter; because the surface of sample 3 has no partitions, there is no data on the length of the tip area and the middle area.

[0135] Table 2: Surface roughness of various locations on the grinding wire of this application

[0136]

[0137] Note: Because sample 3 lacks a partitioned structure, the surface exhibits a relatively uniform micro-pit morphology from the tip to 16 mm from the tip, with the area of ​​these micro-pits ranging from 0.8 to 1.4 μm. 2 Within the range.

[0138] Grab and release test

[0139] The tapered filament samples obtained in Examples 1-3 were made into brushes, and the brushes were used to conduct ink and powder collection and release tests according to the test methods in steps 5 and 6. The results are recorded in Tables 3 and 4 below.

[0140] Table 3: Experimental results of ink grasping and releasing by the brush made from the pointed filaments of this application

[0141] Sample Name Ink volume (mg) Ink dispensing volume (mg) Ink release length (cm) Sample 1 359.4 309.8 22.4 Sample 2 326.6 269.9 17.6 Sample 3 233.6 193.3 11.4

[0142] Table 4: Experimental results of powder compact grasping and releasing by the brush made of the pointed filaments of this application

[0143] sample Average powder intake (mg) Average powder dosage (mg) Sample 1 12.7 6.4 Sample 2 13.5 6.5 Sample 3 11.5 5.6

[0144] It is understood that the above description is only a preferred embodiment of the present invention; for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also within the scope of protection claimed by the present invention.

Claims

1. A tapered filament of a co-extruded monofilament having a core-sheath structure, wherein the core-sheath structure is a sheath-core structure; wherein at least one end of the co-extruded monofilament having the core-sheath structure is chemically treated and tapered to obtain the tapered filament, characterized in that... The sharpened wire comprises, from its tip, a tip region, a middle region, and a rear end region, wherein the tip region, middle region, and rear end region are rough surfaces with different degrees of roughness; and the length of the tip region is ≥4mm, the length of the middle region is 4-50mm, preferably 4-30mm, and more preferably 4-20mm.

2. The tapered filament according to claim 1, wherein the core layer of the core-sheath structure comprises polybutylene terephthalate (PBT) and optionally present additives, or is composed of PBT and optionally present additives; and the sheath layer of the core-sheath structure comprises polypropylene glycol terephthalate (PTT) or PBT and optionally present additives, or is composed of PBT or PBT and optionally present additives.

3. The tapered filament according to claim 1, wherein the diameter of the tapered filament is 0.05-0.5 mm, preferably 0.05-0.3 mm, more preferably 0.05-0.18 mm; and the ratio of the skin thickness of the tapered filament to the diameter of the tapered filament is 5-30%, preferably 10-20%.

4. The tapered wire according to claim 1, wherein the diameter of the tapered wire at a distance of 0.01 mm from the tip is ≤0.05 mm, preferably ≤0.01 mm.

5. The sharpening wire according to any one of claims 1 to 4, wherein the rough surface of the tip region has a pit morphology, and the average area of ​​the pits in the tip region is ≤10 μm. 2 The rough surface at the beginning of the central region contains pores, and the average area of ​​the pores in the beginning region of the central region is >10 μm. 2 The pore area gradually decreases from the beginning to the end of the middle region, and the average pore area at the end of the middle region is >3μm. 2 The surface of the rear end region has micropores, and the average area of ​​the micropores in the rear end region is ≤3μm. 2 Preferably ≤2μm 2 .

6. The tapered filament according to any one of claims 1 to 4, wherein the chemical treatment tapering involves immersing the co-extruded monofilament having a core-sheath structure in a heated alkaline solution, wherein the alkaline solution comprises a sodium hydroxide solution, a potassium hydroxide solution, or a combination thereof.

7. The tipped wire according to any one of claims 1 to 4, wherein the surface of the tipped wire with the core-sheath structure is coated with silicone oil; the silicone oil includes methyl silicone oil, amino silicone oil, phenyl silicone oil, etc.

8. The tapered filament according to any one of claims 1 to 4, wherein the additives in the sheath and / or the core layer include antioxidants, light stabilizers, antistatic agents, lubricants, plasticizers, fillers, antibacterial agents, etc.

9. The tapered wire according to claim 8, wherein the filler comprises at least one of the following: calcium carbonate, barium sulfate, talc, glass fiber, and mica.

10. A method for preparing a tapered filament of a co-extruded monofilament having a core-sheath structure as described in any one of claims 1-9, comprising the following steps: a. Co-extruded monofilaments with a core-sheath structure having a PBT core layer and a PTT sheath layer are obtained by melt co-extrusion; b. The co-extruded monofilament with a core-sheath structure obtained in step a is subjected to chemical sharpening treatment; c. Clean and dry the resulting tapered wire; d. The monofilaments obtained by chemical grinding are coated with silicone oil. e. Optional further post-processing to obtain the final product.

11. The method of claim 10, wherein the chemical sharpening treatment comprises the following steps: The end face of the co-extruded monofilament cake with a core-sheath structure prepared according to the method of claim 10 is immersed in an alkaline solution, and / or the end face of the monofilament cake with a core-sheath structure prepared according to the method of claim 10 is placed horizontally and completely immersed in the alkaline solution.

12. The method according to claim 11, wherein the alkaline solution is selected from sodium hydroxide solution, potassium hydroxide solution, or a combination thereof, preferably sodium hydroxide solution.

13. A brush, said brush being obtained from a tapered filament as described in any one of claims 1 to 9, or from a tapered filament prepared by the method described in any one of claims 10 to 12.

14. The brush as described in claim 13, characterized in that, The brushes mentioned include paintbrushes, makeup brushes, and paintbrushes.

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