PET melt-blown non-woven fabric and preparation process thereof

Abstract

The invention relates to the technical field of melt-blowing, and provides a PET melt-blown non-woven fabric and a preparation process thereof in order to solve the problem that superfine fibers cannot be produced due to insufficient drafting of PET melt-blown fibers. The preparation technology comprises the steps of raw material drying, melt spinning, hot air traction and receiving forming, the raw material is composite resin of PET and hyperbranched polyester containing a carboxyl-terminated structure, the melt index of the composite resin is 100-400 g / 10 min, and the intrinsic viscosity of the composite resin is 0.45-0.55 dL / g; the temperature of melt spinning is 250-300 DEG C, and the temperature is gradually increased in the melt extrusion direction; and the receiving and forming distance is 10-20 cm. And the melt-blown non-woven fabric with fine and uniform fibers, small and uniformly distributed pores and high fiber breaking strength can be prepared. The invention also provides the PET melt-blown non-woven fabric prepared by the preparation process, the fiber diameter is 1-5 microns, and the pore is 1-10 microns; the fibers are oriented longitudinally, and the longitudinal breaking strength is 60-90 N.

Description

Technical Field

[0001] The invention relates to the field of melt-blown technology, in particular to a PET melt-blown nonwoven fabric and a preparation process thereof. Background Art

[0002] Meltblown nonwoven fabrics (also called nonwoven fabrics) have the characteristics of small pore size and high porosity, so they have unique advantages in the field of filtration and can be used for air filtration, liquid filtration, etc. Polyethylene terephthalate (PET) has a high melting point. Compared with olefins, meltblown nonwoven fabrics made of it have higher mechanical strength and better elasticity. PET is the second largest raw material after PP.

[0003] The molecular structure of PET contains benzene rings with high rigidity, poor flexibility, and difficulty in rotation, as well as -CH2 links arranged in a straight line. This makes the overall arrangement of the PET molecular chain regular and the structure neat, so PET has the characteristics of high crystallinity and high orientation. This also makes PET fibers have higher strength and better mechanical properties. For example, patent CN113373597A discloses a method for making non-woven felt from pure PET composite long fibers, and patent CN104358030A discloses a method for preparing a coarse denier high-strength spunbond non-woven fabric, and the fibers used are PET fibers.

[0004] However, there is a relatively rigid benzene ring in the molecular structure of PET, and the benzene ring itself has a stable structure and is not easy to rotate and deform, so it will be affected by a relatively strong steric effect during the movement of PET molecules, and the benzene ring and the ester group will form a conjugated effect, which strengthens the connection between the chain segments, making it difficult to slide against each other, and greatly affecting the flexibility of the PET molecules. Therefore, the presence of a rigid benzene ring and the conjugated effect between the ester group and the benzene ring will offset the flexibility of the -CH2 link, making the PET molecule as a whole rigid. Thus, the characteristics of PET itself, such as large viscosity and poor fluidity, make the fiber drafting insufficient during the melt-blown process, and ultrafine fibers cannot be normally produced. Accordingly, an ideal solution is needed. Summary of the invention

[0005] In order to overcome the problem that PET melt-blown fibers cannot be sufficiently stretched to produce ultrafine fibers, the present invention provides a PET melt-blown non-woven fabric and a preparation process thereof. The raw material is a PET composite resin obtained by compounding a hyperbranched polyester with a terminal carboxyl structure and pure PET. The PET composite resin has high crystal orientation and melt strength. By combining with a specific melt-blowing processing technology, a melt-blown non-woven fabric with fine and uniform fibers, small and uniformly distributed pores, and high fiber breaking strength can be prepared.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The preparation process of PET melt-blown nonwoven fabric includes raw material drying, melt spinning, hot air drawing, and receiving molding. The raw material is a composite resin of PET and a hyperbranched polyester containing a terminal carboxyl structure, the melt index of the composite resin is 100-400g / 10min, and the intrinsic viscosity is 0.45-0.55dL / g; the temperature of the melt spinning is 250-300°C, and the temperature increases with the melt extrusion direction; the receiving distance of the receiving molding is 10-20cm.

[0007] PET meltblown nonwoven fabric is a kind of fabric directly formed by three-dimensional, irregular arrangement of fibers, most of which are ultrafine fibers. However, due to the random irregularity in the drawing and receiving processes, the performance of each fiber is different. In addition, the tensile fracture of nonwoven fabrics is not only related to the mechanical properties of the fibers, but also to the arrangement structure such as bonding and entanglement between the fibers. Therefore, when the material is stretched, the fracture, elongation and slippage of the fibers are not simultaneous. The fracture of the nonwoven fabric does not occur in an instant. The experiment observed that the PET meltblown nonwoven fabric gradually elongated during the pulling process, and the nonwoven fabric deformed as the clamps were separated. The fibers on both sides gathered to the middle and stretched longitudinally at the same time, so that the fibers in the nonwoven fabric were longitudinally oriented. During preparation, it is necessary to focus on the relationship between the die temperature, the traction hot air temperature, the traction air pressure, the crystallization process, and the number of adhesion points.

[0008] The composite resin of the present invention has a high melt strength during melt processing, and its fibers have a high crystal orientation and crystallization rate. According to the rheological characteristics of the PET melt-blown special resin used in the present invention, the melt processing temperature suitable for its processing and the drafting wind pressure during the drafting process are specifically regulated; according to the characteristics of the high crystallization temperature and fast crystallization rate of the PET melt-blown special resin, the receiving distance of the receiving molding process is specifically regulated. With the appropriate melt-blowing processing technology, melt-blown non-woven fabric products with fine and uniform fibers, small and uniformly distributed pores, and high transverse / vertical breaking strength can be prepared.

[0009] Preferably, the mass proportion of the hyperbranched polyester with a carboxyl-terminated structure in the composite resin is 0.1-5wt%. Changes in the content of the hyperbranched polyester will cause changes in the crystallization temperature and crystallization rate of the composite resin, ultimately affecting the performance of the nonwoven fabric.

[0010] Preferably, the drying temperature is 140-160°C and the drying time is 6-8h. The raw material of the present invention has strong water absorption. The presence of water will cause the ester group in the PET molecular structure to undergo hydrolysis reaction and degradation under high temperature. Therefore, the composite resin must be dried before melt-blowing processing. The drying can be carried out in a vacuum drum drying oven.

[0011] Preferably, the melt spinning comprises the following processes in sequence: twin-screw extrusion, metering by a metering pump, melt filtration, and melt ejection through a die head.

[0012] Preferably, the screw extrusion temperature is 250-280°C, the metering pump and filtration zone temperatures are 270-280°C, and the die head temperature is 270-300°C.

[0013] As a further preference, the temperature of screw zone 1 is 250-270°C, the temperature of screw zone 2 is 250-270°C, the temperature of screw zone 3 is 260-280°C, and the temperature of screw zone 4 is 260-280°C; the temperature of die zone 1 is 270-290°C, the temperature of die zone 2 is 270-290°C, the temperature of die zone 3 is 280-300°C, and the temperature of die zone 4 is 280-300°C.

[0014] Preferably, the hot air temperature of the hot air drawing is 330-350°C, and the drawing air pressure is 0.1-0.3MPa.

[0015] Preferably, the PET composite resin contains 0.1-0.3wt% of a hyperbranched polyester with a terminal carboxyl structure, the screw zone temperature of the melt spinning is 260-280°C, and the receiving distance of the receiving molding is 15-20cm; or; the PET composite resin contains 0.5-1wt% of a hyperbranched polyester with a terminal carboxyl structure, the screw zone temperature of the melt spinning is 250-260°C, and the receiving distance of the receiving molding is 10-15cm; or; the PET composite resin contains 3-5wt% of a hyperbranched polyester with a terminal carboxyl structure, the screw zone temperature of the melt spinning is 260-280°C, and the receiving distance of the receiving molding is 15-20cm.

[0016] Changes in the content of hyperbranched polyester will cause changes in the crystallization temperature and crystallization rate of PET melt-blown resin. The die temperature, traction hot air temperature, and traction air pressure need to be adjusted according to this change to ensure that the melt-blown fiber has more adhesion points while completing rapid crystallization, so that the obtained non-woven fabric has a higher breaking strength. When a PET melt-blown special resin with a low hyperbranched polyester content (0.1-0.3%) is selected, the melt fluidity is relatively poor, the die temperature needs to be higher, and the receiving distance needs to be longer to ensure that the fiber can be fully drawn to obtain ultrafine fibers; when a PET melt-blown special resin with a high hyperbranched polyester content (3-5%) is selected, the interaction between the hyperbranched polyester and the PET molecular chain is enhanced during processing, and the molecular entanglement is intensified. At this time, a higher die temperature is also required to ensure that the PET molecules can better crystallize and orient during the drawing process to obtain higher fiber strength; when a PET melt-blown special resin with a medium hyperbranched polyester content (0.5-1%) is selected, the melt fluidity is very good, and good fluidity can still be maintained at a lower die temperature. At this time, the melt strength is high, and drawing and crystallization can be completed under a higher drawing wind pressure within a shorter receiving distance. When forming a non-woven fabric, a lot of bonding points are retained, which greatly improves the tensile strength of the non-woven fabric.

[0017] The present invention also provides a PET melt-blown non-woven fabric prepared by the above-mentioned preparation process, wherein the fiber diameter of the non-woven fabric is distributed in the range of 1-5 μm, and is mainly distributed in the range of 2-4 μm; the pore size is distributed in the range of 1-10 μm, and is mainly distributed in the range of 4-6 μm; the fibers are longitudinally oriented, and the longitudinal breaking strength is between 60-90N.

[0018] Preferably, the longitudinal elongation at break of the fibers of the nonwoven fabric is between 30-40%, the transverse breaking strength is between 40-60N, and the transverse elongation at break is between 20-30%.

[0019] As a preference, the weight of the nonwoven fabric is set at 85-95 g / m 2 The thickness is set between 0.45-0.55mm.

[0020] Preferably, the nonwoven fabric has a filtration efficiency of 90-95% for particles larger than 5 μm and a filtration flux of 25-35 mL.

[0021] Compared with the melt-blown non-woven fabric made of pure PET, the prepared melt-blown non-woven fabric has finer fibers and a more uniform fiber size distribution; smaller pores and a more uniform pore distribution; a greatly improved longitudinal breaking strength and a lower longitudinal elongation; a greatly improved transverse breaking strength and a comparable transverse elongation.

[0022] Therefore, the beneficial effects of the present invention are: (1) Compared with pure PET resin, the composite resin of the present invention maintains better melt strength and fluidity, can effectively stretch to obtain finer fibers under relatively low drafting wind pressure, and complete crystal orientation, and the obtained non-woven fabric product has higher breaking strength. Considering the die head temperature and drafting wind temperature, the composite resin has lower die head temperature and drafting wind temperature (20-30°C lower) during the melt-blowing process than the pure PET resin.

[0023] (2) Compared with pure PET resin, the composite resin of the present invention has a faster fiber crystallization rate and a higher crystallization temperature of the meltblown nonwoven fabric, which can greatly shorten the receiving distance of the meltblown nonwoven fabric during receiving and forming. In the prior art of meltblowing, the receiving distance of receiving and forming is more than 30 cm. The shortening of the receiving distance of the meltblown nonwoven fabric during receiving and forming is conducive to maintaining more bonding points between fibers, which is conducive to improving the tensile breaking strength of the meltblown nonwoven fabric.

[0024] (3) The meltblown nonwoven fabric prepared by the present invention has the advantages of fine and uniform fibers, small and uniformly distributed pores, high transverse / longitudinal breaking strength, and good filtration efficiency, which is mainly attributed to the characteristics of the composite resin having a fast crystallization rate and many fiber melt adhesion points. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is further described below through specific embodiments.

[0026] In the present invention, unless otherwise specified, the raw materials and equipment used can be purchased from the market or are commonly used in the art. The methods in the embodiments, unless otherwise specified, are all conventional methods in the art. Unless otherwise specified, parts are all weight parts, temperatures are expressed in ° C or at ambient temperature, and pressures are atmospheric pressure or near atmospheric pressure. There are many variations and combinations of reaction conditions (such as component concentrations, desired solvents, solvent mixtures, temperatures, pressures, and other reaction ranges) and conditions that can be used to optimize the purity and yield of the product obtained by the method, and only reasonable routine experiments will be required to optimize such method conditions.

[0027] Example A preparation process of a PET melt-blown nonwoven fabric comprises the following steps: raw material drying, melt spinning, hot air drawing, and receiving molding.

[0028] The raw material is a composite resin of PET and a hyperbranched polyester containing a terminal carboxyl structure, the melt index of the composite resin is 100-400 g / 10 min, and the intrinsic viscosity is 0.45-0.55 dL / g. The test conditions of the melt index referred to in the present invention are: temperature 285° C., pressure 1.2 kg.

[0029] The hyperbranched polyester with a terminal carboxyl structure is HBPET, and the mass proportion of HBPET in the composite resin is 0.1-5wt%. HBPET is a hyperbranched high molecular polyester with a terminal carboxyl structure, the terminal carboxyl content is 1000-4000 mol / t, the number of terminal carboxyl groups accounts for 25-100% of the total terminal groups, the degree of branching is 30-100%, the relative molecular weight is 1100-50000 g / mol, and except for the O of the carboxyl and hydroxyl groups, it is composed of C and H. The molecular formula is as follows: The hyperbranched polymer polyester is prepared by the M2+M3 synthesis method, wherein M2 is a monomer containing two reactive groups, at least one of which is a carboxyl group, and M3 is a monomer containing three reactive hydroxyl groups. Preferably, M2 is pyrazine-2,3-dicarboxylic acid, 2-carboxyethylphenylphosphinic acid, 5-tert-butyl-1,3-benzenedicarboxylic acid or 2-carboxyethylphosphoric acid, [(6-oxo-6H-dibenzo[c,e][1,2]oxaphosphorin-6-yl)methyl]succinic acid; and M3 is 1,1,1-tri(hydroxymethyl)propane, tris(2-hydroxyethyl)isocyanurate, 2,4,5-trihydroxybutyrophenone, 2,3,4-trihydroxyacetophenone or 1,2,4-trihydroxybenzene.

[0030] The preparation method of HBPET in the following embodiments refers to the preparation method of substance A in patent CN109721968B, which is specifically "esterification reaction of pyrazine-2,3-dicarboxylic acid and 1,1,1-tri(hydroxymethyl)propane in a molar ratio of 1:1 at a temperature of 150°C under nitrogen protection for 1 hour, and then vacuum polycondensation reaction at a temperature of 200°C and a pressure of 0 MPa for 4 hours to obtain HBPET, wherein stirring is required during the esterification reaction and polycondensation reaction, and the stirring rate is 200 rpm." (1) The drying temperature is 140-160° C. and the drying time is 6-8 hours.

[0031] (2) The temperature of the melt spinning is 250-300°C, and the temperature increases in the direction of melt extrusion. The melt spinning includes the following processes in sequence: twin-screw extrusion, metering by a metering pump, melt filtration, and melt ejection through a die. The temperature process parameters of each process of the melt spinning are: screw zone 1 temperature 250-270°C, screw zone 2 temperature 250-270°C, screw zone 3 temperature 260-280°C, screw zone 4 temperature 260-280°C, metering pump temperature 270-280°C, filtration zone temperature 270-280°C, die zone 1 temperature 270-290°C, die zone 2 temperature 270-290°C, die zone 3 temperature 280-300°C, and die zone 4 temperature 280-300°C.

[0032] The receiving distance of the receiving molding is 10-20cm. There is 0.1-0.3wt% of hyperbranched polyester with terminal carboxyl structure in the PET composite resin, the screw zone temperature of melt spinning is 260-280℃, and the receiving distance of the receiving molding is 15-20cm; or; there is 0.5-1wt% of hyperbranched polyester with terminal carboxyl structure in the PET composite resin, the screw zone temperature of melt spinning is 250-260℃, and the receiving distance of the receiving molding is 10-15cm; or; there is 3-5wt% of hyperbranched polyester with terminal carboxyl structure in the PET composite resin, the screw zone temperature of melt spinning is 260-280℃, and the receiving distance of the receiving molding is 15-20cm.

[0033] The present invention also provides a PET melt-blown non-woven fabric obtained by the above-mentioned preparation process. The fiber diameter of the non-woven fabric is distributed in 1-5 μm, mainly distributed in 2-4 μm; the pore size is distributed between 1-10 μm, mainly distributed between 4-6 μm; the fiber is longitudinally oriented, and the longitudinal breaking strength is between 60-90N. The longitudinal breaking elongation of the fiber of the non-woven fabric is between 30-40%; the transverse breaking strength is between 40-60N, and the transverse breaking elongation is between 20-30%. The gram weight of the non-woven fabric is set at 85-95g / m 2 The thickness is set between 0.45-0.55mm. The filtration efficiency of the non-woven fabric for particles larger than 5μm is 90-95%, and the filtration flux is 25-35mL.

[0034] Example 1 A preparation process of a PET melt-blown nonwoven fabric comprises the following steps: raw material drying, melt spinning, hot air drawing, and receiving molding.

[0035] The raw material is composed of 10% (mass percentage, the same below) of HBPET / PET composite resin masterbatch and 90% of pure PET resin chips. The mass percentage of HBPET in the HBPET / PET composite resin masterbatch is 1%, and the mass percentage of HBPET in the raw material is 0.1%. The melt index of the raw material is 105.6g / 10min (test conditions: temperature 285℃, pressure 1.2kg), and the intrinsic viscosity is 0.53dL / g.

[0036] (1) The above raw materials are dried in a vacuum drum drying oven at a temperature of 160° C. for 8 hours to fully remove the moisture in the PET melt-blown special resin to prevent it from being degraded during the melt processing.

[0037] (2) The melt spinning includes the following processes in sequence: twin-screw extrusion, metering by a metering pump, melt filtering, and melt ejection through a die. The temperature of the melt spinning is 260-300°C, and the temperature increases with the direction of melt extrusion. The specific process parameters of each working area are as follows: screw zone 1 temperature 265°C, screw zone 2 temperature 265°C, screw zone 3 temperature 270°C, screw zone 4 temperature 275°C, metering pump temperature 275°C, filtration zone temperature 275°C, die zone 1 temperature 280°C, die zone 2 temperature 285°C, die zone 3 temperature 290°C, and die zone 4 temperature 295°C.

[0038] (3) The hot air temperature of the hot air drawing is 340° C., the drawing air pressure is 0.1 MPa, and the heat preservation is 20 minutes.

[0039] (4) Add the resin slices of the raw materials to be melt-blown, adjust the receiving distance to 20 cm, and receive the melt-blown non-woven fabric samples.

[0040] Example 2 A preparation process of a PET melt-blown nonwoven fabric comprises the following steps: raw material drying, melt spinning, hot air drawing, and receiving molding.

[0041] The raw material is composed of 10% (mass percentage, the same below) of HBPET / PET composite resin masterbatch and 90% of pure PET resin chips. The mass percentage of HBPET in the HBPET / PET composite resin masterbatch is 5%, and the mass percentage of HBPET in the raw material is 0.5%. The melt index of the raw material is 396.8g / 10min (test conditions: temperature 285℃, pressure 1.2kg), and the intrinsic viscosity is 0.50dL / g.

[0042] (1) The above raw materials are dried in a vacuum drum drying oven at a temperature of 160° C. for 8 hours to fully remove the moisture in the PET melt-blown special resin to prevent it from being degraded during the melt processing.

[0043] (2) The melt spinning includes the following processes in sequence: twin-screw extrusion, metering by a metering pump, melt filtering, and melt ejection through a die. The temperature of the melt spinning is 250-300°C, and the temperature increases with the direction of melt extrusion. The specific process parameters of each working area are as follows: screw zone 1 temperature 250°C, screw zone 2 temperature 250°C, screw zone 3 temperature 260°C, screw zone 4 temperature 260°C, metering pump temperature 275°C, filtration zone temperature 275°C, die zone 1 temperature 280°C, die zone 2 temperature 285°C, die zone 3 temperature 290°C, and die zone 4 temperature 295°C.

[0044] (3) The hot air temperature of the hot air drawing is 340° C., the drawing air pressure is 0.1 MPa, and the heat preservation is 20 minutes.

[0045] (4) Add the resin slices of the raw materials to be melt-blown, adjust the receiving distance to 20 cm, and receive the melt-blown non-woven fabric samples.

[0046] Example 3 The difference from Example 1 is that the mass proportion of the hyperbranched polyester with a terminal carboxyl structure in the composite resin is 0.5wt%, and the intrinsic viscosity of the raw material is 0.50dL / g; among the process parameters of each working area of ​​the melt spinning, the die temperature and the hot air temperature are lower, specifically: the temperature of the die zone 1 is 275°C, the temperature of the die zone 2 is 280°C, the temperature of the die zone 3 is 285°C, and the temperature of the die zone 4 is 285°C; the hot air temperature is set at 330°C during the hot air pulling process.

[0047] A preparation process of a PET melt-blown nonwoven fabric comprises the following steps: raw material drying, melt spinning, hot air drawing, and receiving molding.

[0048] The raw material is composed of 10% (mass percentage, the same below) of HBPET / PET composite resin masterbatch and 90% of pure PET resin chips. The mass percentage of HBPET in the HBPET / PET composite resin masterbatch is 5%, and the mass percentage of HBPET in the raw material is 0.5%. The melt index of the raw material is 396.8g / 10min (test conditions: temperature 285℃, pressure 1.2kg), and the intrinsic viscosity is 0.50dL / g.

[0049] (1) The above raw materials are dried in a vacuum drum drying oven at a temperature of 160° C. for 8 hours to fully remove the moisture in the PET melt-blown special resin to prevent it from being degraded during the melt processing.

[0050] (2) The melt spinning includes the following processes in sequence: twin-screw extrusion, metering by a metering pump, melt filtering, and melt ejection through a die. The temperature of the melt spinning is 250-300°C, and the temperature increases with the direction of melt extrusion. The specific process parameters of each working area are as follows: screw zone 1 temperature 265°C, screw zone 2 temperature 265°C, screw zone 3 temperature 270°C, screw zone 4 temperature 275°C, metering pump temperature 275°C, filtration zone temperature 275°C, die zone 1 temperature 275°C, die zone 2 temperature 280°C, die zone 3 temperature 285°C, and die zone 4 temperature 285°C.

[0051] (3) The hot air temperature of the hot air drawing is 330° C., the drawing air pressure is 0.1 MPa, and the temperature is kept for 20 minutes.

[0052] (4) Add the resin slices of the raw materials to be melt-blown, adjust the receiving distance to 20 cm, and receive the melt-blown non-woven fabric samples.

[0053] Example 4 The difference from Example 1 is that the mass proportion of the hyperbranched polyester with a terminal carboxyl structure in the composite resin is 0.5 wt %, and the intrinsic viscosity of the raw material is 0.50 dL / g.

[0054] A preparation process of a PET melt-blown nonwoven fabric comprises the following steps: raw material drying, melt spinning, hot air drawing, and receiving molding.

[0055] The raw material is composed of 10% (mass percentage, the same below) of HBPET / PET composite resin masterbatch and 90% of pure PET resin chips. The mass percentage of HBPET in the HBPET / PET composite resin masterbatch is 5%, and the mass percentage of HBPET in the raw material is 0.5%. The melt index of the raw material is 396.8g / 10min (test conditions: temperature 285℃, pressure 1.2kg), and the intrinsic viscosity is 0.50dL / g.

[0056] (1) The above raw materials are dried in a vacuum drum drying oven at a temperature of 160° C. for 8 hours to fully remove the moisture in the PET melt-blown special resin to prevent it from being degraded during the melt processing.

[0057] (2) The melt spinning includes the following processes in sequence: twin-screw extrusion, metering by a metering pump, melt filtering, and melt ejection through a die. The temperature of the melt spinning is 250-300°C, and the temperature increases with the direction of melt extrusion. The specific process parameters of each working area are as follows: screw zone 1 temperature 265°C, screw zone 2 temperature 265°C, screw zone 3 temperature 270°C, screw zone 4 temperature 275°C, metering pump temperature 275°C, filtration zone temperature 275°C, die zone 1 temperature 280°C, die zone 2 temperature 285°C, die zone 3 temperature 290°C, and die zone 4 temperature 295°C.

[0058] (3) The hot air temperature of the hot air drawing is 340° C., the drawing air pressure is 0.1 MPa, and the heat preservation is 20 minutes.

[0059] (4) Add the resin slices of the raw materials to be melt-blown, adjust the receiving distance to 20 cm, and receive the melt-blown non-woven fabric samples.

[0060] Example 5 The difference from Example 4 is that the drafting wind pressure is set at 0.15 MPa and the receiving distance is set at 10 cm.

[0061] A preparation process of a PET melt-blown nonwoven fabric comprises the following steps: raw material drying, melt spinning, hot air drawing, and receiving molding.

[0062] The raw material is composed of 10% (mass percentage, the same below) of HBPET / PET composite resin masterbatch and 90% of pure PET resin chips. The mass percentage of HBPET in the HBPET / PET composite resin masterbatch is 5%, and the mass percentage of HBPET in the raw material is 0.5%. The melt index of the raw material is 396.8g / 10min (test conditions: temperature 285℃, pressure 1.2kg), and the intrinsic viscosity is 0.50dL / g.

[0063] (1) The above raw materials are dried in a vacuum drum drying oven at a temperature of 160° C. for 8 hours to fully remove the moisture in the PET melt-blown special resin to prevent it from being degraded during the melt processing.

[0064] (2) The melt spinning includes the following processes in sequence: twin-screw extrusion, metering by a metering pump, melt filtering, and melt ejection through a die. The temperature of the melt spinning is 250-300°C, and the temperature increases with the direction of melt extrusion. The specific process parameters of each working area are as follows: screw zone 1 temperature 265°C, screw zone 2 temperature 265°C, screw zone 3 temperature 270°C, screw zone 4 temperature 275°C, metering pump temperature 275°C, filtration zone temperature 275°C, die zone 1 temperature 280°C, die zone 2 temperature 285°C, die zone 3 temperature 290°C, and die zone 4 temperature 295°C.

[0065] (3) The hot air temperature of the hot air drawing is 340° C., the drawing air pressure is 0.15 MPa, and the heat preservation is 20 minutes.

[0066] (4) Add the resin slices of the raw materials to be melt-blown, adjust the receiving distance to 10 cm, and receive the melt-blown non-woven fabric sample.

[0067] Example 6 The difference from Example 4 is that the drafting air pressure is set at 0.2 MPa.

[0068] A preparation process of a PET melt-blown nonwoven fabric comprises the following steps: raw material drying, melt spinning, hot air drawing, and receiving molding.

[0069] The raw material is composed of 10% (mass percentage, the same below) of HBPET / PET composite resin masterbatch and 90% of pure PET resin chips. The mass percentage of HBPET in the HBPET / PET composite resin masterbatch is 5%, and the mass percentage of HBPET in the raw material is 0.5%. The melt index of the raw material is 396.8g / 10min (test conditions: temperature 285℃, pressure 1.2kg), and the intrinsic viscosity is 0.50dL / g.

[0070] (1) The above raw materials are dried in a vacuum drum drying oven at a temperature of 160° C. for 8 hours to fully remove the moisture in the PET melt-blown special resin to prevent it from being degraded during the melt processing.

[0071] (2) The melt spinning includes the following processes in sequence: twin-screw extrusion, metering by a metering pump, melt filtering, and melt ejection through a die. The temperature of the melt spinning is 250-300°C, and the temperature increases with the direction of melt extrusion. The specific process parameters of each working area are as follows: screw zone 1 temperature 265°C, screw zone 2 temperature 265°C, screw zone 3 temperature 270°C, screw zone 4 temperature 275°C, metering pump temperature 275°C, filtration zone temperature 275°C, die zone 1 temperature 280°C, die zone 2 temperature 285°C, die zone 3 temperature 290°C, and die zone 4 temperature 295°C.

[0072] (3) The hot air temperature of the hot air drawing is 340° C., the drawing air pressure is 0.2 MPa, and the heat preservation is 20 minutes.

[0073] (4) Add the resin slices of the raw materials to be melt-blown, adjust the receiving distance to 20 cm, and receive the melt-blown non-woven fabric samples.

[0074] Example 7 The difference from Example 1 is that the mass proportion of the hyperbranched polyester with a terminal carboxyl structure in the composite resin is 5 wt %, and the intrinsic viscosity of the raw material is 0.45 dL / g.

[0075] A preparation process of a PET melt-blown nonwoven fabric comprises the following steps: raw material drying, melt spinning, hot air drawing, and receiving molding.

[0076] The raw material is composed of 10% (mass percentage, the same below) of HBPET / PET composite resin masterbatch and 90% of pure PET resin chips. The mass percentage of HBPET in the HBPET / PET composite resin masterbatch is 5%, and the mass percentage of HBPET in the raw material is 0.5%. The melt index of the raw material is 396.8g / 10min (test conditions: temperature 285℃, pressure 1.2kg), and the intrinsic viscosity is 0.50dL / g.

[0077] (1) The above raw materials are dried in a vacuum drum drying oven at a temperature of 160° C. for 8 hours to fully remove the moisture in the PET melt-blown special resin to prevent it from being degraded during the melt processing.

[0078] (2) The melt spinning includes the following processes in sequence: twin-screw extrusion, metering by a metering pump, melt filtering, and melt ejection through a die. The temperature of the melt spinning is 250-300°C, and the temperature increases with the direction of melt extrusion. The specific process parameters of each working area are as follows: screw zone 1 temperature 265°C, screw zone 2 temperature 265°C, screw zone 3 temperature 270°C, screw zone 4 temperature 275°C, metering pump temperature 275°C, filtration zone temperature 275°C, die zone 1 temperature 280°C, die zone 2 temperature 285°C, die zone 3 temperature 290°C, and die zone 4 temperature 295°C.

[0079] (3) The hot air temperature of the hot air drawing is 340° C., the drawing air pressure is 0.1 MPa, and the heat preservation is 20 minutes.

[0080] (4) Add the resin slices of the raw materials to be melt-blown, adjust the receiving distance to 20 cm, and receive the melt-blown non-woven fabric samples.

[0081] Comparative Example 1 The difference from Example 1 is that: ① the raw material is pure PET resin, and does not contain hyperbranched polyester with terminal carboxyl structure. ② in the process parameters of each working area of ​​melt spinning, the screw temperature is higher and the drafting air pressure is greater, specifically: the temperature of screw zone 1 is 265°C, the temperature of screw zone 2 is 270°C, the temperature of screw zone 3 is 275°C, and the temperature of screw zone 4 is 280°C; the drafting air pressure is set at 0.2MPa.

[0082] A preparation process of a PET melt-blown nonwoven fabric comprises the following steps: raw material drying, melt spinning, hot air drawing, and receiving molding.

[0083] (1) The raw material is pure PET resin. The raw material is dried in a vacuum drum drying oven at a temperature of 160°C for 8 hours to fully remove the moisture in the PET melt-blown special resin to prevent it from being degraded during the melt processing.

[0084] (2) The melt spinning includes the following processes in sequence: twin-screw extrusion, metering by a metering pump, melt filtering, and melt ejection through a die. The temperature of the melt spinning is 250-300°C, and the temperature increases with the direction of melt extrusion. The specific process parameters of each working area are as follows: screw zone 1 temperature 265°C, screw zone 2 temperature 270°C, screw zone 3 temperature 275°C, screw zone 4 temperature 280°C, metering pump temperature 275°C, filtration zone temperature 275°C, die zone 1 temperature 280°C, die zone 2 temperature 285°C, die zone 3 temperature 290°C, and die zone 4 temperature 295°C.

[0085] (3) The hot air temperature of the hot air drawing is 340° C., the drawing air pressure is 0.2 MPa, and the heat preservation is 20 minutes.

[0086] (4) Add the resin slices of the raw materials to be melt-blown, adjust the receiving distance to 20 cm, and receive the melt-blown non-woven fabric samples.

[0087] Comparative Example 2 The difference from Example 1 is that: ① the raw material is pure PET resin, and does not contain hyperbranched polyester with a terminal carboxyl structure; ② in the process parameters of each working area of ​​the melt spinneret, the temperature is higher and the drawing wind pressure is greater; specifically: the temperature of screw zone 1 is 265°C, the temperature of screw zone 2 is 280°C, the temperature of screw zone 3 is 300°C, the temperature of screw zone 4 is 310°C, the temperature of the metering pump is 310°C, the temperature of the filtration zone is 310°C, the temperature of die zone 1 is 315°C, the temperature of die zone 2 is 325°C, the temperature of die zone 3 is 330°C, and the temperature of die zone 4 is 335°C; during the hot air drawing process, the hot air temperature is set at 350°C, and the drawing wind pressure is set at 0.15MPa; ③ the receiving distance is shorter, which is 15cm.

[0088] A preparation process of a PET melt-blown nonwoven fabric comprises the following steps: raw material drying, melt spinning, hot air drawing, and receiving molding.

[0089] (1) The raw material is pure PET resin. The raw material is dried in a vacuum drum drying oven at a temperature of 160°C for 8 hours to fully remove the moisture in the PET melt-blown special resin to prevent it from being degraded during the melt processing.

[0090] (2) The melt spinning includes the following processes in sequence: twin-screw extrusion, metering by a metering pump, melt filtering, and melt ejection through a die. The temperature of the melt spinning is 250-300°C, and the temperature increases with the direction of melt extrusion. The specific process parameters of each working area are as follows: screw zone 1 temperature 265°C, screw zone 2 temperature 280°C, screw zone 3 temperature 300°C, screw zone 4 temperature 310°C, metering pump temperature 310°C, filtration zone temperature 310°C, die zone 1 temperature 315°C, die zone 2 temperature 325°C, die zone 3 temperature 330°C, and die zone 4 temperature 335°C.

[0091] (3) The hot air temperature of the hot air drawing is 350° C., the drawing air pressure is 0.15 MPa, and the heat preservation is 20 minutes.

[0092] (4) Add the resin slices of the raw materials to be melt-blown, adjust the receiving distance to 15 cm, and receive the melt-blown non-woven fabric samples.

[0093] Comparative Example 3 The existing preparation process of PET melt-blown non-woven fabrics comprises the following steps: raw material drying, melt spinning, hot air drawing, and receiving molding.

[0094] (1) The raw material is pure PET resin. The raw material is dried in a vacuum drum drying oven at a temperature of 160°C for 8 hours to fully remove the moisture in the PET melt-blown special resin to prevent it from being degraded during the melt processing.

[0095] (2) The melt spinning includes the following processes in sequence: twin-screw extrusion, metering by a metering pump, melt filtering, and melt ejection through a die. The temperature of the melt spinning is 250-300°C, and the temperature increases with the direction of melt extrusion. The specific process parameters of each working area are as follows: screw zone 1 temperature 285°C, screw zone 2 temperature 295°C, screw zone 3 temperature 310°C, screw zone 4 temperature 320°C, metering pump temperature 320°C, filtration zone temperature 320°C, die zone 1 temperature 320°C, die zone 2 temperature 325°C, die zone 3 temperature 330°C, and die zone 4 temperature 335°C.

[0096] (3) The hot air temperature of the hot air drawing is 350° C., the drawing air pressure is 0.1 MPa, and the heat preservation is 20 minutes.

[0097] (4) Add the resin slices of the raw materials to be melt-blown, adjust the receiving distance to 32 cm, and receive the melt-blown non-woven fabric samples.

[0098] Comparative Example 4 The difference from Example 1 is that the receiving distance is less than 10 cm, which is lower than the preferred range.

[0099] A preparation process of a PET melt-blown nonwoven fabric comprises the following steps: raw material drying, melt spinning, hot air drawing, and receiving molding.

[0100] The raw material is composed of 10% (mass percentage, the same below) of HBPET / PET composite resin masterbatch and 90% of pure PET resin chips. The mass percentage of HBPET in the HBPET / PET composite resin masterbatch is 1%, and the mass percentage of HBPET in the raw material is 0.1%. The melt index of the raw material is 105.6g / 10min (test conditions: temperature 285℃, pressure 1.2kg), and the intrinsic viscosity is 0.53dL / g.

[0101] (1) The above raw materials are dried in a vacuum drum drying oven at a temperature of 160° C. for 8 hours to fully remove the moisture in the PET melt-blown special resin to prevent it from being degraded during the melt processing.

[0102] (2) The melt spinning includes the following processes in sequence: twin-screw extrusion, metering by a metering pump, melt filtering, and melt ejection through a die. The temperature of the melt spinning is 250-300°C, and the temperature increases with the direction of melt extrusion. The specific process parameters of each working area are as follows: screw zone 1 temperature 265°C, screw zone 2 temperature 265°C, screw zone 3 temperature 270°C, screw zone 4 temperature 275°C, metering pump temperature 275°C, filtration zone temperature 275°C, die zone 1 temperature 280°C, die zone 2 temperature 285°C, die zone 3 temperature 290°C, and die zone 4 temperature 295°C.

[0103] (3) The hot air temperature of the hot air drawing is 340° C., the drawing air pressure is 0.1 MPa, and the heat preservation is 20 minutes.

[0104] (4) When the resin slices of the raw materials to be melt-blown are added and the receiving distance is adjusted to 5 cm, the melt cannot be effectively stretched under the action of hot air. After the melt is ejected, a large number of material points are formed on the receiving roller, and a non-woven fabric cannot be formed.

[0105] Comparative Example 5 The difference from Example 1 is that the receiving distance is greater than 20 cm, which is beyond the preferred range.

[0106] A preparation process of a PET melt-blown nonwoven fabric comprises the following steps: raw material drying, melt spinning, hot air drawing, and receiving molding.

[0107] The raw material is composed of 10% (mass percentage, the same below) of HBPET / PET composite resin masterbatch and 90% of pure PET resin chips. The mass percentage of HBPET in the HBPET / PET composite resin masterbatch is 1%, and the mass percentage of HBPET in the raw material is 0.1%. The melt index of the raw material is 105.6g / 10min (test conditions: temperature 285℃, pressure 1.2kg), and the intrinsic viscosity is 0.53dL / g.

[0108] (1) The above raw materials are dried in a vacuum drum drying oven at a temperature of 160° C. for 8 hours to fully remove the moisture in the PET melt-blown special resin to prevent it from being degraded during the melt processing.

[0109] (2) The melt spinning includes the following processes in sequence: twin-screw extrusion, metering by a metering pump, melt filtering, and melt ejection through a die. The temperature of the melt spinning is 250-300°C, and the temperature increases with the direction of melt extrusion. The specific process parameters of each working area are as follows: screw zone 1 temperature 265°C, screw zone 2 temperature 265°C, screw zone 3 temperature 270°C, screw zone 4 temperature 275°C, metering pump temperature 275°C, filtration zone temperature 275°C, die zone 1 temperature 280°C, die zone 2 temperature 285°C, die zone 3 temperature 290°C, and die zone 4 temperature 295°C.

[0110] (3) The hot air temperature of the hot air drawing is 340° C., the drawing air pressure is 0.1 MPa, and the heat preservation is 20 minutes.

[0111] (4) Add the resin slices of the raw materials to be melt-blown, adjust the receiving distance to 25 cm, and receive the melt-blown non-woven fabric samples.

[0112] Performance Characterization The breaking strength of meltblown nonwoven fabrics was tested by HD026N+ electronic fabric strength tester according to GB / T 24218.3-2010. The test method was the strip method, and the cut strips should be more than 10 cm away from the edge of the nonwoven fabric. The longitudinal direction refers to the direction perpendicular to the arrangement of the spinneret holes, and the transverse direction refers to the direction parallel to the spinneret holes. The clamping length between the upper and lower clamps of the fabric strength tester is 10 cm. The sample needs to be placed through the two ends of the sample through the clamp to ensure that the sample is clamped tightly. The constant elongation speed of the clamp is 10 cm / min. The tensile breaking strength and tensile breaking elongation of the sample in the longitudinal (MD) and transverse (CD) directions were tested. The fiber size and distribution of the meltblown nonwoven samples after gold spraying were detected by scanning electron microscopy. The minimum pore size, maximum pore size, pore size distribution, etc. of the sample can be tested by using the CFP-1100AI aperture tester. At the same time, the gram weight, thickness and filtration efficiency of particles above 5μm of the sample were also compared. Meltblown processability is the meltblown processability of the raw material, which is judged by naked eyes and divided into four levels: poor, general, good, and good. The comparison results are shown in Table 1.

[0113] Table 1. Properties of meltblown nonwoven fabrics obtained in Examples and Comparative Examples As can be seen from Table 1, the composite resin containing terminal carboxyl hyperbranched polyester used in the embodiment has better melt-blown processability than the pure PET resin used in Comparative Examples 1 and 2, and its melt-blown non-woven fabric products also have better performance. Moreover, Comparative Examples 1 and 2 use pure PET resin, and melt-blown processing needs to be carried out at a higher temperature, and relatively good processability is required at above 300°C, but the performance of its melt-blown non-woven fabric products is poor, and the uneven drafting leads to a wide size distribution of non-woven fabric fibers and pores, low filtration efficiency for particles, and low mechanical strength of the non-woven fabric.

[0114] Comparing the various embodiments, it can be seen that the process conditions of the meltblowing process have a great influence on the performance of the meltblown non-woven fabric products. Therefore, in order to obtain a meltblown non-woven fabric with excellent performance after meltblowing with a meltblown special PET resin, suitable process conditions are required.

[0115] Comparing Examples 2-4, the melt-blown processability is better when the processing temperature reaches above 250°C. On this basis, simply increasing the processing temperature improves the performance of the product, but the improvement is not significant.

[0116] Comparing Examples 2, 4, and 5, it can be seen that shortening the nonwoven receiving distance on the basis of increasing the temperature can obtain more uniform fibers, and the corresponding nonwoven products have higher mechanical strength. This is mainly attributed to the characteristics of the selected PET melt-blown special resin with fast crystallization rate and high crystallization temperature. At this processing temperature, the drafting wind can well complete the drafting effect on the melt. During this drafting process, the fibers are quickly oriented and crystallized longitudinally, so that the fibers have a higher longitudinal breaking strength. After shortening the receiving distance, the drafted fibers have more bonding points when they fall on the receiving platform, which can greatly improve the transverse breaking strength of the nonwoven fabric.

[0117] The PET melt-blown special resin has a fast crystallization rate during melt-blowing processing. After the receiving distance is shortened to 10 cm, it can still complete longitudinal orientation and crystallization during the stretching process. The receiving distance set in the traditional melt-blown non-woven fabric processing process (i.e., Comparative Example 3) is more than 30 cm, so as to ensure that the fiber can be fully stretched and crystallized. However, the extension of the receiving distance will inevitably reduce the number of bonding points after the fiber reaches the receiving platform. The reduction in bonding points will greatly weaken the tensile breaking strength of the non-woven fabric, especially the transverse breaking strength.

[0118] Compared with Example 1, the receiving distance of Comparative Example 4 is too short, and it cannot be effectively stretched under the action of hot air. After the melt is ejected, a large number of material points are formed on the receiving roller, and a non-woven fabric cannot be formed; the receiving distance of Comparative Example 5 is too long, and the performance of the melt-blown non-woven fabric product is poor. Therefore, the receiving distance needs to be controlled within a reasonable range to achieve better experimental results.

[0119] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. The preparation process of PET melt-blown nonwoven fabric is characterized in that: The process includes raw material drying, melt spinning, hot air drawing and receiving molding. The raw material is a composite resin of PET and a hyperbranched polyester containing a terminal carboxyl structure. The melt index of the composite resin is 100-400 g / 10min and the intrinsic viscosity is 0.45-0.55 dL / g. The temperature of the melt spinning is 250-300°C and the temperature increases with the direction of melt extrusion. The receiving distance of the receiving molding is 10-20 cm.

2. The preparation process of the PET melt-blown nonwoven fabric according to claim 1, characterized in that: The mass proportion of the hyperbranched polyester with a terminal carboxyl structure in the composite resin is 0.1-5wt%.

3. The preparation process of the PET melt-blown nonwoven fabric according to claim 1 or 2, characterized in that: The drying temperature is 140-160°C and the drying time is 6-8 hours.

4. The preparation process of the PET melt-blown nonwoven fabric according to claim 1, characterized in that: The melt spinning process includes the following steps in sequence: Screw extrusion, metering pump metering, melt filtering, and melt ejection through the die head.

5. The preparation process of the PET melt-blown nonwoven fabric according to claim 4, characterized in that: The screw extrusion temperature is 250-280 ℃, the metering pump and filtration zone temperature is 270-280 ℃, and the die head temperature is 270-300 ℃.

6. The process for preparing the PET melt-blown nonwoven fabric according to claim 4 or 5, characterized in that: The screw extrusion is divided into four zones, the temperature of screw zone 1 is 250-270°C, the temperature of screw zone 2 is 250-270°C, the temperature of screw zone 3 is 260-280°C, the temperature of screw zone 4 is 260-280°C, and the temperature is increasing.

7. The process for preparing the PET melt-blown nonwoven fabric according to claim 1, 4 or 5, characterized in that: The hot air temperature of the hot air drawing is 330-350° C., and the drawing air pressure is 0.1-0.3 MPa.

8. The PET melt-blown non-woven fabric obtained by the preparation process of the PET melt-blown non-woven fabric according to any one of claims 1 to 7, characterized in that: The fiber diameter of the non-woven fabric is distributed in the range of 1-5 μm; the pore size is distributed in the range of 1-10 μm; the fibers are longitudinally oriented, and the longitudinal breaking strength is between 60-90 N.

9. The PET melt-blown nonwoven fabric according to claim 8, characterized in that: The weight of non-woven fabric is 85-95 g / m 2 , thickness is 0.45-0.55 mm.

10. The PET melt-blown nonwoven fabric according to claim 8 or 9, characterized in that: The filtration efficiency of nonwoven fabric for particles larger than 5 μm is 90-95%, and the filtration flux is 25-35 mL.

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