CN112043030A

CN112043030A - Manufacturing method of melt-blown non-woven fabric, melt-blown non-woven fabric and product

Info

Publication number: CN112043030A
Application number: CN202011050178.9A
Authority: CN
Inventors: 冯建国
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-08-04
Filing date: 2020-09-29
Publication date: 2020-12-08
Anticipated expiration: 2040-09-29
Also published as: CN111789333A; CN112043030B

Abstract

The invention provides a manufacturing method of melt-blown non-woven fabric, melt-blown non-woven fabric and a product. The manufacturing method of the melt-blown non-woven fabric comprises the following steps: conveying the feed liquid to a die head structure; jetting a drawing air flow by using a jet orifice of the die head structure, and simultaneously delivering the feed liquid by using a liquid jet orifice of the die head structure, so that the drawing air flow can draw the delivered feed liquid along a jetting direction; wherein the feed liquid contains melted raw materials for manufacturing melt-blown nonwoven fabrics, and the drawing airflow or the feed liquid is mixed with target materials, and the target materials comprise chitin and/or derivatives of the chitin.

Description

Manufacturing method of melt-blown non-woven fabric, melt-blown non-woven fabric and product

Technical Field

The invention relates to the field of melt-blown non-woven fabrics, in particular to a manufacturing method of a melt-blown non-woven fabric, a melt-blown non-woven fabric and a product.

Background

A nonwoven fabric, which can be described as: non Woven Fabric or Non Woven cloth, otherwise known as Nonwoven Fabric, is made up of oriented or random fibers. The melt-blown non-woven fabric is a non-woven fabric made by the existing specific process equipment, belongs to a non-woven fabric woven by high polymer chemical synthetic fibers, and can be simply understood as an industrial product which adopts a screw machine to melt chemical fiber raw materials with hot melting and then sprays liquid raw materials extruded from a spinneret orifice into a large amount of loose fibers by hot air flow to randomly pile up the loose fibers into a fabric.

In the related art, the raw material may be a high molecular fusible material, for example, a modified PP raw material is used, which is a raw material formed by combining a PP material and tourmaline, that is, a raw material called electret masterbatch, and the raw material may have a function of storing charges.

However, even in the melt-blown nonwoven fabric made of modified PP, static electricity is usually maintained for only about four hours, and further, the time for which the mask (or other corresponding products) can actually adsorb particles is not long, and if the protection effect needs to be ensured, the mask (or other corresponding products) needs to be replaced every several hours, and further, besides the increase of cost, much inconvenience is caused to the user. Therefore, the mask (or other corresponding products) manufactured by the existing process is difficult to effectively consider the cost and the protection effect.

Disclosure of Invention

The invention provides a manufacturing method of a melt-blown non-woven fabric, the melt-blown non-woven fabric and a product, and aims to solve the problem that cost and protection are difficult to effectively consider.

According to a first aspect of the present invention, there is provided a method of manufacturing a melt-blown nonwoven fabric, comprising:

conveying the feed liquid to a die head structure;

jetting a drawing air flow by using a jet orifice of the die head structure, and simultaneously delivering the feed liquid by using a liquid jet orifice of the die head structure, so that the drawing air flow can draw the delivered feed liquid along a jetting direction;

wherein the feed liquid contains a molten raw material for producing a melt-blown nonwoven fabric, and the draw air flow or the feed liquid is mixed with a target material, wherein the target material comprises chitin or a derivative of the chitin.

Optionally, before the feed liquid is delivered to the die structure, the method further comprises:

mixing the target material with the molten raw materials to form the feed solution.

Optionally, mixing the target material and the melted raw material together to form the feed liquid, specifically including:

mixing the melted chitin derivative and the melted raw materials together to form the feed liquid.

Optionally, mixing the melted chitin derivative with the melted raw materials to form the feed liquid, including:

mixing the derivative of the chitin with the raw materials to prepare a material master batch, and adding the material master batch into a screw machine to form the feed liquid in the screw machine;

or:

adding a derivative of chitin into a screw machine, so that a raw material melted in the screw machine is mixed with the derivative of chitin to form the feed liquid;

wherein the feed liquid can reach the die structure through the conveying of the screw machine.

mixing the powder of chitin with the melted raw materials to form the feed liquid so that: the feed liquid contains chitin powder.

Optionally, mixing the chitin powder with the melted raw materials to form the feed liquid, including:

mixing chitin powder with raw materials to prepare a material master batch, and adding the material master batch into a screw machine to form the feed liquid in the screw machine;

and/or:

adding chitin powder into a screw machine, so that the raw materials melted in the screw machine are mixed with the chitin powder to form the feed liquid;

and/or:

Optionally, the injection port is directly or indirectly communicated with the gas conveying channel;

before the jet of the pulling gas flow is sprayed by the jet opening of the die structure, the method further comprises the following steps:

adding a powder of the target material to a gas delivery channel such that: the pulling gas stream has a powder of the target material therein.

Optionally, the speed of the air flow after the pulling air flow is ejected reaches a target speed, and the target speed is higher than the speed of sound.

Optionally, the derivative of chitin is chitosan.

According to a second aspect of the present invention, there is provided a melt-blown nonwoven fabric produced by the method for producing a melt-blown nonwoven fabric according to the first aspect and the alternatives thereof.

According to a third aspect of the present invention there is provided a product comprising the meltblown nonwoven fabric of the second aspect and its alternatives.

Optionally, the product is a hygienic product, and the hygienic product is any one of the following: mask, operating coat, protective clothing, disinfection cloth, diaper, sanitary towel.

Optionally, the melt-blown nonwoven fabric is provided with spunbond layers on both sides.

In the manufacturing method of the melt-blown non-woven fabric, the melt-blown non-woven fabric and the product provided by the invention, as the chitin or the derivative thereof has positive static charges, after the chitin or the derivative thereof is added, the manufactured melt-blown non-woven fabric can have more positive static charges, and further, the attenuation period of static contained in the melt-blown fabric under the natural condition can be favorably prolonged, and the effective service time of the corresponding product is also prolonged.

Meanwhile, dust particles (also containing bacteria and viruses) in the nature contain positive static charges and negative static charges, after the scheme of the invention is adopted, the positive static charges of the melt-blown cloth are enhanced, the dust particles containing the positive charges cannot enter or are limited to enter the melt-blown cloth due to the action of repelling of like charges, and once the dust particles containing the negative static charges meet, the melt-blown cloth can powerfully prevent the dust particles from passing through due to the action of attraction of the positive charges and the negative charges. Therefore, the chitin or the derivative thereof can effectively enhance the filtering capacity of the melt-blown fabric.

Therefore, the manufactured melt-blown fabric has larger static electricity and stronger dust particle filtering capacity. The invention can not only improve PFE (particle protection effect) but also improve BFE and VFE (bacteria and virus protection effect), according to the principle of polymer material pharmacology, the surface film of bacteria and virus has negative charges, through the positive charges in chitin or derivatives thereof, the surface film can be damaged due to the action of the positive charges and the negative charges, and further the invention has the function of killing bacteria and virus.

In addition, it should be pointed out that there are some solutions to spray a chitin layer on the surface of the melt-blown fabric, and for this kind of technology, although the gaps between the fibers can be blocked to some extent, a film-like structure can be formed after spraying, and although the filtration rate can be improved (after all, there are few gaps that can flow through), the air permeability will be reduced, and it is seen that the way of coating the chitin layer will cause: the higher the filtration rate, the lower the air permeability, and the lower the filtration rate and the air permeability cannot be considered at the same time. In contrast, the present invention can form a film-like structure without spraying, and is advantageous in terms of both filterability and air permeability.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a first schematic flow chart illustrating a method for manufacturing a meltblown nonwoven fabric according to an embodiment of the present invention;

FIG. 2 is a second schematic flow chart illustrating a method for manufacturing a meltblown nonwoven fabric according to an embodiment of the present invention;

FIG. 3 is a third schematic flow chart illustrating a method for manufacturing a meltblown nonwoven fabric according to an embodiment of the present invention;

FIG. 4 is a fourth schematic flow chart illustrating a method for manufacturing a meltblown nonwoven fabric according to an embodiment of the present invention;

FIG. 5 is a schematic flow chart illustrating a method for manufacturing a meltblown nonwoven fabric according to an embodiment of the present invention;

FIG. 6 is a schematic representation of a drawn fiber;

FIG. 7 is a schematic cross-sectional view of a first mold structure of an apparatus for making meltblown nonwoven fabric according to an embodiment of the present invention;

FIG. 8 is a schematic representation of the structural form of a Laval tube in accordance with an embodiment of the present invention;

FIG. 9 is a schematic sectional view of a second embodiment of a mold head structure of an apparatus for making meltblown nonwoven fabric;

FIG. 10 is a schematic sectional view of a mold head structure of an apparatus for making meltblown nonwoven fabric according to an embodiment of the invention;

FIG. 11 is a schematic cross-sectional view of a die structure of an apparatus for making meltblown nonwoven fabric according to an embodiment of the invention;

FIG. 12 is a schematic partial cross-sectional view of a die structure of an apparatus for making meltblown nonwoven fabric according to an embodiment of the present invention;

fig. 13 is a schematic structural diagram of a die structure in a meltblown nonwoven fabric manufacturing apparatus according to an embodiment of the present invention.

Description of reference numerals:

1-a die head structure;

101-a groove;

102-a gas chamber;

103-liquid feed cavity;

104-an injection port;

105-an exit surface;

1051-a first surface;

1052-a second surface;

106-liquid spraying port;

107-groove body;

108-die body.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The terms "first," "second," "third," "fourth," and the like in the description and in the claims, as well as in the drawings, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

The technical solution of the present invention will be described in detail below with specific examples. The following several specific embodiments may be combined with each other, and details of the same or similar concepts or processes may not be repeated in some embodiments.

Referring to fig. 1, a method for manufacturing a melt-blown nonwoven fabric includes:

s1: conveying the feed liquid to a die head structure;

s2: and jetting a drawing air flow by using the jet orifice of the die head structure, and simultaneously delivering the feed liquid by using the liquid jet orifice of the die head structure, so that the drawing air flow can draw the delivered feed liquid along the jetting direction.

In step S2, the discharged feed liquid may be pulled to the receiving surface by an air flow to form a meltblown web (i.e., a meltblown nonwoven).

The feed liquid according to the embodiment of the present invention may be understood as including high-temperature molten raw materials, that is: the feed liquid contains a molten raw material for producing a melt-blown nonwoven fabric, and may be a molten material that may contain a non-liquid material (e.g., tourmaline, chitin powder, etc.), and further, the drawing gas flow or the feed liquid contains a target material including chitin or a derivative of chitin.

Chitin can be characterized as Chitin, which is a homopolysaccharide formed by connecting N-acetyl-2-amino 2-deoxy-D-glucose in a beta-1 and 4 glycosidic bond form, and is an organic high molecular compound with the second existing amount in nature next to cellulose. The method has various characteristics, and the characteristics applied by the embodiment of the invention comprise the following steps: the amino group in the chitin molecule has positive charge. In addition, Chitosan (Chitosan) can be regarded as a modified chitin, a deacetylated chitin, which is one of the aforementioned "derivatives". Meanwhile, the derivative of chitin is not limited to chitosan.

In addition, it should be noted that the chitin and its derivatives according to the embodiments of the present invention refer to natural biopolymer fiber materials, not chemically synthesized polymer materials.

Taking the manufacturing process of the melt-blown nonwoven fabric in the mask as an example (similar processes are adopted in the manufacturing process in other scenes), the whole process may include, for example:

charging raw materials → extruding screw rod → metering and conveying metering pump → spraying by die head → receiving rack surface → forming static electricity by electret generator → coiling cloth.

The above step S2 of the present embodiment can be understood as a partial or entire process in which the die performs spinning, and the above step S1 can be, for example, a process of at least one of the above raw material feeding, screw extrusion, metering and conveying by a metering pump.

The raw material may be a raw material made of polypropylene (PP), for example, in this case, the raw material may be referred to as PP masterbatch, the raw material may be a raw material made of other Polyester (PET), for example, the raw material may be referred to as PET masterbatch, and the raw material may be a raw material made of other polymer meltable material.

In the raw material, other materials with corresponding functions (such as tourmaline or chitin and derivatives thereof mentioned in the embodiments of the present invention) can be added to form a material master batch with corresponding functions, which can be understood as modified materials (or modified raw materials) on the basis of the raw materials. The material master batch added with tourmaline can also be called electret master batch, which is only an example and is not limited to this.

In some embodiments of the present invention, the chitin (or its derivative) may be added to the raw material to be made into a modified material of the chitin (or its derivative) during the preparation of the raw material, or the chitin (or its derivative) may be added to the screw machine.

Therefore, in the scheme, as the chitin or the derivative thereof has positive static charges, after the chitin or the derivative thereof is added, the prepared melt-blown non-woven fabric can have more positive static charges, and further, the attenuation period of static charges contained in the melt-blown fabric under the natural condition can be favorably prolonged, and the effective service time of corresponding sanitary products (such as masks) or other products is prolonged.

Specific means for adding chitin or its derivatives will be specifically exemplified below with reference to fig. 2 to 5. In the embodiment shown in fig. 2 to 4, the target material can be mixed into the feed liquid, and in the embodiment shown in fig. 5, the target material can be mixed into the drawing gas flow.

Referring to fig. 2, before step S1, the method may further include:

s3: mixing the target material with the molten raw materials to form the feed solution.

Among them, there are various possibilities for the target material, and accordingly, there are also process differences. Several possible ways will be exemplified below in connection with fig. 3 and 4.

Referring to fig. 3, in one embodiment, the target material includes a derivative of chitin (e.g., chitosan), and then: step S3 may include:

s31: mixing the melted chitin derivative and the melted raw materials together to form the feed liquid.

Further, step S31 may include:

and/or:

adding chitin powder into a screw machine, and mixing the raw materials melted in the screw machine with the chitin powder to form the feed liquid.

In a specific example, when melt-blowing cloth layer is used in the manufacturing of mask, chitosan derivative (such as chitosan) can be added into the screw machine used in the process (II), and the chitosan can be melted together with the melted raw material (such as modified PP or other high polymer meltable material used in the traditional process) in the screw machine and then fused with each other. At this time, the chitin derivative melted in the raw material can be ejected through the die head structure along with the feed liquid. In other examples, the derivative of chitin (e.g. chitosan) may be mixed with the raw material and made into a material master batch, and then the material master batch is added into the screw machine used in the process (ii).

Referring to fig. 4, in one embodiment, the target material includes chitin, in which a powder of chitin may be used, and step S3 may include:

s32: mixing the powder of chitin with the melted raw materials to form the feed liquid so that: the feed liquid contains chitin powder.

Wherein, the powder of chitin can adopt very fine powder, and then the guarantee: the chitin powder can meet the requirement of a liquid spraying port so as to be suitable for being sent out. According to the performance requirement of the melt-blown fabric, the liquid-jet orifice can be designed to be required size, as long as the process requirement is met, and the chitin powder can be sprayed out through the design of the size of the liquid-jet orifice, so that the embodiment of the invention is not specifically exemplified here.

In addition, in some prior arts, there is 80 nm tourmaline in the melt-blown feed liquid, and the tourmaline with the size can be suitable for being sent out from the liquid-spraying opening, and then chitin powder with suitable size (for example, less than or equal to 80 nm) can also be sent out from the liquid-spraying opening naturally.

Specifically, step S32 may include:

mixing chitin powder with raw materials, making into material master batches, and adding the material master batches into a screw machine to form the feed liquid in the screw machine;

and/or:

In a specific example, when the fabric layer is melt-blown in the mask, chitin powder can be added into a screw machine adopted in the process (II), the chitin powder can be mixed with a molten raw material in the screw machine, and the chitin can be kept into powder. At the moment, the chitin powder can be sprayed out through the die head structure along with the feed liquid. In other examples, the chitin powder can also be mixed with the raw materials to prepare a material master batch, and then the material master batch is added into a screw machine adopted in the second process.

In the process of preparing the material masterbatch in the schemes of the steps S31 and S32, the masterbatch can be prepared by combining with required chemical additives (such as an antioxidant, an anti-decomposition additive and the like). In addition, an auxiliary (for example, an antioxidant, an anti-decomposition auxiliary, etc.) may be added to the screw machine.

The schemes of steps S31 and S32 may be alternatively implemented or simply implemented.

Referring to fig. 5, in addition to adding a target material to a raw material, a powder of the target material may be mixed in the drawing gas flow. Meanwhile, the timing of the addition of the powder of the target material may be arbitrary, that is: the powder of the target material may be added at any position between the blower and the ejection port. It can also be understood as: the delivery passage can be any one or more sections of passage parts which can deliver gas between the fan and the jet orifice, and furthermore, the jet orifice is directly or indirectly communicated with the gas delivery passage.

In one example, a feed port (e.g., one or more small holes) for feeding the target material powder may be provided in the side wall of the feed passage, and the feed port may be further provided with a member for controlling the amount of the powder fed by metering, for example, a member for achieving uniform feeding. In another example, the feed port may also be provided with a feed device having anti-recoil capabilities.

In a specific example, a device having both the above uniform feeding capability and the anti-backflushing capability may be used, for example, the feeding port may be provided with a screw feeder.

Correspondingly, referring to fig. 5, before step S2, the method may further include:

s4: adding a powder of the target material to a gas delivery channel such that: the pulling gas stream has a powder of the target material therein.

In the scheme, the superfine powder of the chitin can be ejected to a receiving surface along with high-pressure and high-speed traction gas and feed liquid, and at the moment, the superfine powder of the chitin can be embedded into the cavities among fibers because the airflow is high-temperature and high-pressure.

In some embodiments, the above steps S3 and S4 may be combined to realize a dual addition manner of chitin and its derivatives, such as: the chitin and/or its derivative (such as chitin powder and/or chitosan) can be added into the raw materials, and the very fine powder chitin can be added into the gas conveying channel. Meanwhile, in step S3, the target material may be added to the raw material in one manner, or the target material may be added to the raw material in more than one manner.

In addition, besides the chitin powder, other infusible materials can be added into the gas delivery channel.

In one embodiment, the velocity of the air flow after the pulling air flow is ejected reaches a target velocity, and the target velocity is higher than the speed of sound.

In contrast, existing die structures typically do not provide for the pulling gas to flow beyond transonic velocity, wherein, due to insufficient pressure, the hot gas stream is not ejected at a high velocity and is located a short distance from the receiving surface, which results in insufficient space for the fibers to be fully drawn, the fibers are not fine enough, and the dope exiting the die is at temperatures of more than 200 degrees celsius, such that filaments at high temperatures often stick together on the receiving surface, and further, the exiting filaments may be side-by-side or intertwined on the receiving surface, as shown in fig. 6. Wherein the black and white parts are two filaments, respectively, of which only two simpler cases are illustrated. Therefore, the existing production operation process is further very complex, and the required filtration rate and air permeability can not be achieved synchronously.

When the configuration of the drawing airflow is higher than the sound velocity, the full drawing of the fibers can be facilitated, so that thinner fibers are formed, and the condition that the fibers are stuck together on the receiving surface is effectively avoided or alleviated.

Also, the actual situation may be much more complex, with more voids, or large-scale voids, between fibers on the receiving surface that are not densified by the hot gas stream, due to the various random states of the fibers, and particles that easily pass through.

Part current scheme can be at the surface of melt-blown cloth scribble chitin layer again, and to this type of prior art, though can be at the clearance of certain shutoff fibre within a definite time, nevertheless, can form similar film form's structure after the spraying, though can improve the filtration rate (after all the circulated clearance is few), but the gas permeability can descend, and it is visible, the mode of coating chitin layer can cause: the higher the filtration rate, the lower the air permeability, and the lower the filtration rate and the air permeability cannot be considered at the same time.

In comparison, the target material can block gaps among fibers to a certain degree, can avoid forming a separate film-shaped structure, and can effectively take filtering performance and air permeability into consideration.

In addition, in the above scheme, the structure of the die head enables the drawing air flow to reach supersonic speed, so that the time that the target material (chitin and/or derivatives thereof) is in a high-temperature environment in the whole process is effectively reduced, the target material is likely to be decomposed when being in a certain high-temperature environment, and therefore, the decomposition of the target material can be greatly reduced by designing a supersonic speed process, so that the quality stability of the target material can be effectively improved, and the electrostatic charge content is ensured, so that the effect of effective sterilization is achieved.

One alternative way to help bring the pulling air stream to sonic velocity is described below in connection with fig. 7-13.

Referring to fig. 7, the apparatus for manufacturing a meltblown nonwoven fabric includes: the die head structure 1 is provided with a groove 101 on one side of the die head structure 1, the bottom of the groove 101 is provided with an exit surface 105, and the exit surface 105 is provided with at least one row of liquid jet ports 106 and two groups of jet ports 104; the two groups of injection ports 104 are respectively disposed at two sides of the at least one row of liquid injection ports 106, for example, at the left and right sides (which may be understood as two sides along the first direction) shown in fig. 1, and two gas cavities 102 for flowing pulling gas and a material liquid cavity 103 for flowing melting material are disposed in the die head structure 1; the liquid cavity 103 is connected with the at least one row of liquid injection ports 106 to form a channel for sending out molten materials, and each gas cavity 102 is correspondingly connected with a group of injection ports 104 to form a channel for sending out drawing gas.

The number of rows of the liquid ejecting openings 106 may be one as shown in the figure, or may be two or more rows, for example, if the number of rows of the liquid ejecting openings 106 is two or more rows, the liquid ejecting openings 106 in each row are distributed along the second direction, at least two rows of the liquid ejecting openings are distributed along the first direction, and the first direction and the second direction are perpendicular to each other. The shape of the liquid spray opening can be any regular or irregular pattern, such as a circle or a diamond.

Wherein the jet port 104 may be any port structure capable of jetting a pulling gas stream. In one example, the set of injection ports 104 may include a row of injection ports, which may be distributed along the second direction; in another example, the group of ejection openings 104 may include an elongated ejection opening, which may be understood as a slit-like ejection opening. The ejection port therein may also be described as an ejection port.

In the embodiment of the present invention, the closer the gas chamber 102 is to the injection port 104, the smaller the cross-sectional area of the gas chamber 102 is; in the groove 101, the sectional area of the groove 101 is smaller as the distance from the ejection port 104 is closer;

the cross-sectional area is an area of a cross-section perpendicular to a melt sending direction. The above variation in cross-sectional area may be linear or non-linear, as long as the variation in cross-sectional area satisfies the above description, without departing from the scope of the embodiments of the present invention.

Referring to fig. 8, when the airflow velocity reaching the L-plane reaches the speed of sound (referred to as mach 1), then:

for a convergent section (e.g., the gas chamber 102), the smaller the cross-sectional area of the gas flow path, the velocity of the gas flow satisfies: the closer to the L surface, the higher the speed;

for the expanded pipe section (e.g., the groove 101), the larger the cross-sectional area of the gas flow passage, the velocity of the gas flow satisfies: the further from the L-plane, the higher the velocity.

In one embodiment, the melt-blown nonwoven fabric manufacturing apparatus for achieving sonic velocity further comprises a gas delivery assembly (not shown) directly or indirectly communicating with the gas chamber; the gas delivery assembly is configured to deliver a pulling gas to the gas cavity such that a gas flow velocity of the pulling gas from the jet orifice is greater than or equal to sonic velocity.

The gas delivery assembly may, for example, comprise a gas delivery channel directly or indirectly connecting the gas chamber and the injection orifice, a blower, and may further comprise other components capable of providing gas power, and the gas flow velocity of the pulling gas of the injection orifice may be greater than or equal to the sonic velocity by at least one of the blower, related components of the gas power, and the cross-sectional area of the gas delivery channel.

It can be seen that the velocity of the gas flow at the L-plane reaches sonic velocity to act as a constriction (e.g., gas chamber 102) and an expansion (e.g., groove 101). In some embodiments, other acceleration structures (e.g., the aerodynamic related components mentioned above) may be added to achieve this flow rate. In the actual implementation process, if the structures such as the airflow channel of the existing manufacturing equipment can meet the speed requirement, a corresponding structure can be added on the basis of the existing structure to form a shrinking and expanding pipe, if the speed of the jet orifice of the original structure is less than the sound speed (namely the requirement cannot be met), the inner hole structure of the original structure can be reconstructed according to the requirement of the invention, so that the inner hole structure conforms to the principle of a Laval pipe.

It can be seen that the embodiment of the present invention can be beneficial to increase the speed of the pulling airflow, and in the case that the speed of the ejected airflow is higher than the speed of sound, a higher airflow speed (i.e. increased dynamic pressure) can be formed than that of the conventional structure, and correspondingly, the airflow can be ejected for a longer distance. Further, the high velocity gas flow kinetic energy can forcefully draw the filaments into finer fibers than conventional structures. The specific surface area of the fiber is improved along with the improvement of the fiber degree, the chitin powder is blown into gaps among the fibers, the problems of doubling and winding are solved, the defect of a cavity is filled, and finally the air permeability and the filterability are effectively considered.

In other schemes in the prior art, the research work in the aspect of considering how to make the size of the molten material hole small is generally emphasized, and the development of recent years at home and abroad is not few, and the common direction is to draw chemical fibers sprayed by a spray head into microfiber through hot air flow, so that the smaller the pore diameter, the larger the specific surface area, the less the particles are, and the better the quality of the finished product of the melt-blown fabric is.

However, limited to the limitations of machining techniques, the area of the liquid ejection port cannot be reduced without limit, in other words, the degree of reduction in the size of the liquid ejection port is limited by the processing capability, which results in: a. the solution of small-sized liquid jet cannot be generally applied, and b, the reduction degree of the liquid jet is limited.

In contrast, in the embodiment of the present invention, through the introduction of the convergent-divergent pipe (i.e. the combination of the convergent section such as the gas chamber 102 and the divergent section such as the groove 101), the flow rate and the pressure of the jet are higher, the length of the fiber which is drawn is longer, the fiber is thinner, and therefore a larger specific surface area is achieved, and the filtration rate of the product is increased.

Meanwhile, the sound velocity refers to the local sound velocity: for example, at 15 degrees celsius, the sonic velocity is 340 m/s, but at 25 degrees celsius, the sonic velocity is 346 m/s, which is called mach 1 (the ratio of the actual jet velocity to the sonic velocity is 1), so mach 1 is based on the local sonic velocity and is not a fixed value.

When the scheme is applied to the production of the melt-blown fabric, if one atmosphere pressure of the local environment is taken as a condition, an empirical formula can be introduced: the velocity V (m/s) is 331.3 (sound velocity at 0 ℃) +0.606t (t is temperature).

If the temperature of the workshop environment is 25 ℃, the speed of the spray pipe 1 Mach is 346 m/s. If the hot air flow jet speed required by production is 519 m/s, namely Mach 1.5, the relationship between the sectional area change and the flow velocity change can be researched according to the flow characteristic equation in the Laval nozzle pipe, and the proper air jet opening size is designed to achieve the jet speed at the hot air flow expansion pipe opening required by the design target.

In conjunction with fig. 9, the characteristic equation is:

wherein:

ma is Mach number;

a is the sectional area;

v is the flow velocity;

the above equation is called the flow characteristic equation in the pipe, and gives the relationship between the Mach number, the change rate of the sectional area and the change rate of the flow velocity.

To facilitate understanding of the above characteristic equations, the following is further explained:

the characteristic equation can be obtained by derivation of a continuity equation and an Euler equation of motion;

the continuity equation is: ρ VA is a constant;

the euler equation of motion is:

for the laval tube, there are:

in one embodiment, referring to fig. 7 to 13, the groove 101 has two opposite and non-parallel side surfaces, and the closer the ejection opening 104 is in the groove 101, the smaller the distance between the two side surfaces is.

Taking fig. 7, 10 to 13 as an example, the two side surfaces are flat surfaces, and taking fig. 10 as an example, the two side surfaces may also be curved surfaces, and the curved surfaces may include circular arc surfaces, for example. In some examples, the side surface may include both a flat surface and a curved surface. The side wall formed by the side face can be a straight line taper, and can also be various curves, such as a hyperbolic curve, a parabolic curve or an irregular curve. The side surfaces may be symmetrical or asymmetrical, and the sectional area may be reduced or increased without departing from the scope of the embodiment of the present invention, regardless of the change in shape or size.

Any solution for forming the above structural form, whether it is integrally formed or assembled, does not depart from the scope of the embodiments of the present invention.

Wherein the air inlet and air jet directions of the die structure can be from top to bottom (as shown in figure 12) or horizontal (as shown in figure 11).

In one embodiment, referring to fig. 10 to 13, the die structure 1 includes a die body 108 and two groove bodies 107, the exit surface 105 is a partial surface of a first side surface of the die body 108, and the gas cavity 102 and the liquid cavity 103 are both disposed in the die body 108, where shapes, sizes, and the like of the gas cavity and the liquid cavity are not limited to the examples in the drawings.

The two slot bodies 107 connect a first side of the die body 108 (which may be, for example, the upper side as shown in fig. 11) to form the recess 101 between two opposing sides of the two slot bodies 107 and the first side of the die body, with the exit surface 105 located between the two slot bodies 107.

Wherein the groove body 107 and the die body 108 are fixedly connected together, for example, by a threaded structure or other means.

In one example, the spacing distance between the two groove bodies 107 is adjustable. By adjusting and determining the position of the groove body 107, the sectional area of the groove 101 can be changed, thereby meeting the requirement of flow rate change.

In one embodiment, referring to fig. 13, the exit surface 105 has a first surface 1051 and a second surface 1052, the second surfaces 1052 are respectively disposed on two sides of the first surface, the ejection opening 104 is disposed on the second surface 1052, the at least one row of liquid ejection openings 106 are disposed on the first surface 1051, an included angle between the first surface 1051 and the second surface 1052 is less than 180 degrees, and a certain inclined included angle can be formed between the ejection opening 104 and the liquid ejection openings 106.

In an example, the included angle between the first surface 1051 and the second surface 1052 may be 120 degrees, and correspondingly, the included angle between the injection direction of the gas and the discharge direction of the feed liquid may be 60 degrees.

In summary, the specific scheme of the embodiment of the invention can bring the following effects:

a. the positive charge of the chitin or the derivative thereof is enhanced, the positive charge attracts various dust particles (which can comprise bacteria and viruses) with negative charge, the dust particles do not pass through the three-dimensional netted melt-blown cloth, and the filtering effect is obviously stronger than that of the traditional process (without the chitin).

b. The chitin added from the gas conveying channel has the single superposition effect of positive charges, is mainly attached to the surface of the microfiber, overcomes the defect that filaments are fused together under the conditions of filament doubling and filament winding in the traditional process, and cannot cause the loss of the air permeability of melt-blown cloth when the filtering capacity is enhanced. Meanwhile, the holes in the three-dimensional net structure generated when the original microfiber is laid on the receiving surface are effectively filled, so that the spatial physical dimension of the holes is smaller than that of dust particles, and the function of filtering the dust particles containing bacteria or viruses is further achieved.

c. The Laval tube is used, so that the Laval tube has a new function of breaking through the speed limit of hot air flow in the original melt-blown fabric production, the fiber is drawn to be thinner, the effect of larger specific surface area of the fiber is achieved, and the filterability is improved; the defects that the viscosity of the raw materials is increased and the fibers are not easy to stretch during the production of the melt-blown fabric due to the addition of the chitin in the raw materials are effectively overcome, and the kinetic energy is high-speed and strong and is sprayed to a receiving surface to form the new-generation melt-blown fabric.

Therefore, the scheme provides a mode of double addition (namely that the sprayed feed liquid contains the target material and the sprayed airflow also contains the target material) adopted by the chitin and the derivatives (chitin and chitosan) in the manufacture of the melt-blown fabric, the mode introduces a new production mechanism, changes the traditional production process for manufacturing the melt-blown fabric in the chemical fiber field, and opens a new exploration direction for the research work in the field of more effective antibacterial and antiviral materials.

In addition, when chitin or derivatives thereof and the structural form of the Laval tube are introduced, during cloth forming, the chitin introduced into the hot gas flow channel is filled into the original larger-size cavities along with high-speed gas flow by the huge jet force generated by the contraction and expansion tube, and further, the sprayed filaments cannot (or are not easy to) stick together on a receiving surface, so that higher filtration rate and air permeability can be achieved, the cavity size of the three-dimensional net structure of the melt-sprayed cloth is smaller, and the passage of dust particles is blocked. Meanwhile, the defect that chitin is sprayed on the surface of the melt-blown fabric in the prior art is overcome, and particularly, a plane thin film layer with a cubic network structure cannot be formed, so that the air permeability cannot be weakened. Further, the air permeability and the filtration rate can be effectively considered.

The embodiment of the invention provides a melt-blown non-woven fabric which is manufactured by the manufacturing method of the melt-blown non-woven fabric related to the alternative scheme.

The embodiment of the invention also provides a product comprising the melt-blown non-woven fabric related to the alternative scheme.

In one example, the product can be a hygiene article, which can be any one of: mask, operating coat, protective clothing, disinfection cloth, diaper, sanitary towel. Examples of sanitary articles are also not limited to the above list.

In another example, the product may also be an air filtration product, such as a protective filter screen for a fresh air system.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for manufacturing melt-blown non-woven fabric is characterized by comprising the following steps:

conveying the feed liquid to a die head structure;

wherein the feed liquid contains melted raw materials for manufacturing melt-blown nonwoven fabrics, and the drawing airflow or the feed liquid is mixed with target materials, and the target materials comprise chitin and/or derivatives of the chitin.

2. The method of claim 1, wherein prior to delivering the feed solution to the die structure, further comprising:

3. The method of claim 2, wherein mixing the target material and the melted raw material to form the feed solution comprises:

4. The method of claim 3, wherein the step of mixing the melted chitin derivative with the melted raw material to form the feed solution comprises:

and/or:

5. The method of claim 2, wherein mixing the target material and the melted raw material to form the feed solution comprises:

6. The method of claim 5, wherein the step of mixing chitin powder with melted raw materials to form the feed solution comprises:

and/or:

7. The melt-blown nonwoven fabric production method according to any one of claims 1 to 6, wherein the jet port is directly or indirectly communicated with a gas delivery passage;

8. The method of manufacturing a meltblown nonwoven fabric according to any of claims 1 to 6, characterised in that the air flow velocity after the draw air flow is ejected reaches a target velocity, which is higher than the sonic velocity.

9. A melt-blown nonwoven fabric produced by the method for producing a melt-blown nonwoven fabric according to any one of claims 1 to 8.

10. A product comprising the melt blown nonwoven fabric of claim 9.