Special-shaped core body and disposable hygienic product

Abstract

The utility model belongs to the technical field of personal care, and particularly relates to a special-shaped core body and a disposable hygienic product, the special-shaped core body comprises a composite core body, the composite core body comprises a middle core body layer, the two sides of the middle core body layer are subjected to continuous or discontinuous special-shaped cutting, the special-shaped cutting shape is a regular shape or an irregular shape, and the middle core body layer is made of plastic. The regular shape comprises a wave shape, a triangle shape and a square shape. The special-shaped core body can be directly applied as an absorber layer of the disposable hygienic product, and the disposable hygienic product applying the special-shaped core body has the advantages that the structure is attractive, the infiltration speed of liquid is increased, and the special-shaped core body has a good rapid infiltration effect.

Description

Technical Field

[0001] This utility model relates to the field of hygiene products, specifically an irregularly shaped core and disposable hygiene products. Background Technology

[0002] The core is a crucial component of disposable hygiene products, serving as the primary absorbent element. Currently, most cores on the market are composite cores, which are generally straight strips with a uniform shape and little variation in height on the surface and around the edges. This can easily lead to liquid buildup, affecting the rate of absorption. Utility Model Content

[0003] The purpose of this section is to outline some aspects of the embodiments of this utility model and to briefly introduce some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be used to limit the scope of this utility model.

[0004] This utility model provides the following technical solutions to solve one or more of the above-mentioned technical problems:

[0005] An irregular core includes a composite core, which includes an intermediate core layer. The two sides of the intermediate core layer are regular or irregular shapes or a combination of both. The regular shapes include wavy, triangular, square, etc.

[0006] In some implementations...

[0007] The regular shape is wavy, and after irregular cutting, a wavy line is formed. The wavy line satisfies the following formula.

[0008]

[0009] In the formula for Wave height at location, The height of the wave crest. The distance between the wave crests. The total length of the wavy line. The number of peaks, To observe the altitude, for , This indicates the location of the first peak.

[0010] The formula satisfied by the wave line simplifies to:

[0011]

[0012] In some implementations, the peak height The wave crest spacing is 5% to 45% of the total width W of the composite core. The total length of the wavy line 1% to 100%, number of crests greater than or equal to 1, total length of wavy lines It is 10% to 100% of the total length of the composite core.

[0013] In some embodiments, the two sides of the intermediate core layer are not wavy, and the lateral cutting depth is... The distance between two adjacent protrusions on one side of the intermediate core layer is 5% to 45% of the total width W of the composite core. Total cutting length 1%~100%, the number of protrusions on one side of the intermediate core layer is greater than or equal to 1, and the total cutting length It is 10% to 100% of the total length of the composite core.

[0014] In some embodiments, the intermediate core layer includes a lower hydrophilic nonwoven fabric, a first loose fabric, a second loose fabric, and an upper hydrophilic nonwoven fabric arranged sequentially from bottom to top. Both the first and second loose fabrics are coated with superabsorbent polymer, which is evenly distributed in the pores of the first and second loose fabrics.

[0015] In some implementations...

[0016] The superabsorbent polymer is evenly distributed on the corresponding first and second tufted fabrics, and / or evenly distributed in the pores on both sides of the first and second tufted fabrics.

[0017] The composite core also includes a hydrophilic covering fabric disposed on the outside of the central core layer;

[0018] The two sides of the intermediate core layer are irregularly cut to form a cut area and an uncut area. The hydrophilic covering fabric corresponding to the cut area includes an upper covering layer and a lower covering layer. The upper covering layer and the lower covering layer on both sides of the intermediate core layer are either bonded and sealed or not sealed.

[0019] A disposable hygiene product comprising the irregularly shaped core described in any of the above claims.

[0020] In some embodiments, the disposable hygiene product includes an upper structure, an absorbent layer, and a lower structure. The absorbent layer is a composite core, and the upper and lower structures are located on the upper and lower sides of the absorbent layer. The upper structure, absorbent layer, and lower structure are combined to form a whole.

[0021] In some implementations...

[0022] The upper structure includes a three-dimensional protective enclosure and a surface layer. The surface layer includes an upper non-woven fabric layer and a lower non-woven fabric layer. The three-dimensional protective enclosure is provided with a first elastic band, and the three-dimensional protective enclosure is also provided with a second elastic band on the left and right sides. The rear end of the upper structure is the back waist part of the disposable sanitary product, which is provided with an elastic waistband. The width of the upper non-woven fabric layer is less than or equal to the width of the lower non-woven fabric layer.

[0023] The lower structure includes a bottom nonwoven fabric and a bottom film arranged from bottom to top;

[0024] The surface layer is divided into sections with embossing, and the number of sections is greater than or equal to 2.

[0025] In some implementations...

[0026] The surface layer includes at least three different sections. The middle section is called the middle area. The embossing points in the middle area are gradient points, which gradually decrease from the center line of the surface layer to both sides. The first and second rows of embossing points are staggered or aligned. The height of the embossing points in the areas on both sides of the middle area is greater than or equal to the height of the center embossing point of the middle area, so that the surface layer forms a structure that is low in the middle and high on both sides.

[0027] The number of gradient points is greater than or equal to 2, and the length L1 and width W1 of the next gradient point are 30% to 98% of the length L1 and width W1 of the previous point.

[0028] Compared with the prior art, the advantages of this utility model are: beautiful structure, fast infiltration rate, good absorption effect, and prevention of side leakage. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of this utility model, the present utility model will be described in detail below with reference to the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Among them:

[0030] Figure 1 This is a plan view of a disposable sanitary product according to some embodiments of this utility model;

[0031] Figure 2 yes Figure 1 Schematic diagram of the cross-sectional structure of the middle AA section;

[0032] Figure 3 yes Figure 1 Schematic diagram of the cross-sectional structure of the middle BB section;

[0033] Figure 4 This is a plan view of the continuous wavy cut of the composite core in some embodiments of this utility model;

[0034] Figure 5 yes Figure 4 Schematic diagram of the cross-sectional structure of the middle CC section;

[0035] Figure 6 yes Figure 4 Schematic diagram of the cross-sectional structure between C1 and C1;

[0036] Figure 7 yes Figure 4 Schematic diagram of the cross-sectional structure between C2 and C2;

[0037] Figure 8 This is a schematic diagram of the manual pressurization instrument structure in some embodiments of this utility model;

[0038] Figure 9 This is a schematic diagram of the composite core with polymers distributed on both sides in some embodiments of this utility model;

[0039] Figure 10 This is a transverse cross-sectional view after liquid absorption when the polymer of the composite core is distributed on both sides in some embodiments of this utility model.

[0040] Figure 11 This is a schematic diagram of the partitioned 3D embossed surface layer in some embodiments of this utility model;

[0041] Figure 12 This is a cross-sectional view of the partitioned 3D embossing in some embodiments of this utility model;

[0042] Figure 13 This is a plan view of the intermittent wavy cut of the composite core in some embodiments of this utility model;

[0043] Figure 14 It is an application Figure 13 The diagram shows the unfolded plan view of a disposable hygiene product that conforms to the core.

[0044] Figure 15 This is the composite core cutting shape of Example 1 of this utility model;

[0045] Figure 16 This is the composite core cutting shape of Example 2 of this utility model;

[0046] Figure 17 This is the composite core cutting shape of Example 3 of this utility model. Detailed Implementation

[0047] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings.

[0048] Many specific details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0049] Secondly, this utility model is described in detail with reference to the schematic diagrams. When describing the embodiments of this utility model, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not adhering to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of this utility model. In addition, actual manufacturing should include the three-dimensional spatial dimensions of length, width, and depth.

[0050] To make the objectives, technical solutions, and advantages of this utility model clearer, the embodiments of this utility model will be described in further detail below with reference to the accompanying drawings.

[0051] Combination Figures 1 to 17 As shown in the embodiment, this invention proposes an irregularly shaped core, including a composite core 7. The composite core 7 includes a middle core layer 24, and the two sides of the middle core layer 24 are irregularly cut. The shape of the irregular cut can be regular or irregular, such as wavy, triangular, or square, with a wavy shape being preferred. Irregularly shaped cuts of shapes other than wavy can form, for example... Figures 15 to 17 The composite core structure is shown. The irregular cutting described herein can be continuous or intermittent.

[0052] The aforementioned irregular cut has a wavy shape, and the cut edge is a wavy line, which satisfies the following formula.

[0053] ,

[0054] In the formula for Wave height at location, The height of the wave crest. This refers to the crest spacing (the distance between two crests). The total length of the wavy line. The number of peaks, To observe the height (for example, I need to know the height of the wave crest at x=300). for , This indicates the location of the first peak.

[0055] The formula that the above wavy lines satisfy can be simplified to:

[0056] ,

[0057] Both through The phase difference relationship together determines the position of any position Wave height at the location .

[0058] The above peak height The wave crest spacing can be 5% to 45% of the total width W of the composite core 7, and the wave crest spacing can be the total length of the wave line. The percentage ranges from 1% to 100%, the number of peaks can be greater than or equal to 1, and the total length of the wave line... It can be 10% to 100% of the total length of the composite core 7.

[0059] When the shape of the irregular cut is not wavy, the lateral cutting depth The distance between two adjacent protrusions on one side of the intermediate core layer can be 5% to 45% of the total width W of the composite core 7. Total cutting length 1%~100%, the number of protrusions on one side of the intermediate core layer is greater than or equal to 1, and the total cutting length It is 10% to 100% of the total length of the composite core 7.

[0060] The aforementioned intermediate core layer 24 may include, from bottom to top, a lower layer of hydrophilic nonwoven fabric 21, a first loose fabric 22, a second loose fabric 23, and an upper layer of hydrophilic nonwoven fabric 20. Both the first loose fabric 22 and the second loose fabric 23 are coated with superabsorbent polymer 32, which is uniformly distributed in the pores of the first loose fabric 22 and the second loose fabric 23. The superabsorbent polymer 32 described herein can be uniformly distributed on the corresponding first loose fabric 22 and second loose fabric 23 (e.g., ...). Figure 5 and Figure 6 (as shown), and / or evenly distributed in the pores on both sides of the first and second tufted fabrics 22 and 23.

[0061] like Figure 9 As shown, the superabsorbent polymer 32 is only evenly distributed in the pores on both sides of the first and second tufted fabrics 22 and 23. After the urine is absorbed by the absorbent, the superabsorbent polymer 32 will swell after absorption. Because the superabsorbent polymer 32 is distributed in the pores on both sides of the first and second tufted fabrics 22 and 23, the area on both sides will be higher than the middle position after absorbing the urine, creating a bulge K, thereby accelerating the seepage of urine. Figure 10 , 11 As shown.

[0062] The composite core 7 also includes a hydrophilic covering fabric 19 disposed on the outside of the central core layer 24. The two sides of the central core layer 24 are irregularly cut to form a cut area 18 and an uncut area 17. The hydrophilic covering fabric 19 includes an upper covering layer 19-1 and a lower covering layer 19-2. The upper covering layer 19-1 and the lower covering layer 19-2 on both sides of the central core layer 24 are either bonded and sealed or not sealed.

[0063] The aforementioned hydrophilic covering fabric 19, lower hydrophilic nonwoven fabric 21, and upper hydrophilic nonwoven fabric 20 can be one of hot-air nonwoven fabric, hot-pressed nonwoven fabric, spunlace nonwoven fabric, and spunbond nonwoven fabric.

[0064] The total width W of the aforementioned intermediate core layer 24 can be 100 mm, the crest height can be 10 mm, and the crest spacing can be 100 mm. When the irregular cutting is continuous, the total length of the wavy lines is equal to the total length of the composite core 7, the length of the composite core 7 can be 375 mm, and the number of crests can be 4. For example... Figure 13 and Figure 14 As shown, when the irregular cutting is intermittent, the absorption capacity of the core can be improved, and the leakage at the front and back can be reduced. The total length L3 of the wavy line accounts for 10-100% of the total length of the composite core 7. The total length L3 of the wavy line can preferably be 300mm, and the length of the composite core 7 can be 375mm.

[0065] like Figures 4 to 7 As shown, because the two sides of the intermediate core layer 24 in the composite core 7 are irregularly cut, after urine is absorbed by the intermediate core layer 24, it will expand after the superabsorbent polymer 32 has absorbed it. Under the same amount of urine, because the intermediate core layer 24 is irregularly cut, the area of ​​the two sides of the intermediate core layer 24 is smaller, and its expansion speed is faster, resulting in a height difference H between the cut area 18 and the uncut area 17. Because the cut-off intermediate core layer 24 is correspondingly provided with a hydrophilic covering fabric 19, this height difference H is more obvious, and the urine will... Figure 7 As indicated by the middle arrow P, the liquid flows from high to low, reducing liquid accumulation and accelerating the infiltration rate.

[0066] By manually applying pressure and adding liquid to simulate the scenario of infant use, the test showed that the liquid seepage rate of the composite core 7, which had undergone irregular cutting, was significantly faster than that of the core that had not undergone irregular cutting.

[0067] Specific manual pressurization and liquid addition testing methods can be applied as follows: Figure 8The pressure instrument 29 shown includes a hollow cylindrical liquid filling tank 30 and a circular pressure base 31 located at the bottom of the liquid filling tank 30. The liquid filling tank 30 has a liquid filling port at the top, and the diameter T of the liquid filling port can be 25 mm. The weight of the entire pressure instrument 29 can be 2.4 kg. Specific experimental equipment used in the manual pressure and liquid filling test method may also include filter paper, a graduated cylinder, sodium chloride solution (0.9%), a stopwatch, a measuring ruler, two pressure blocks (1.2 kg / block), and an electronic balance (accurate to 0.01 g).

[0068] The specific method for manual pressurization and liquid addition testing may include the following steps:

[0069] Step 1: Lay the composite core 7 or the disposable sanitary product using the composite core 7 flat and straighten it on a horizontal table; weigh a certain amount of filter paper M1 (about 15g) and another certain amount of filter paper M2 (about 10g), place the filter paper at the bottom center of the sample, and place the pressure device at the center of the sample absorption core.

[0070] Step 2: Accurately measure a certain amount of sodium chloride solution (0.9%) using a graduated cylinder (NB / S#: 40ml, M#: 60ml, L / XL / XXL#: 80ml).

[0071] Step 3: Pour the sodium chloride solution from the graduated cylinder into the pressurization device within 3-5 seconds and start timing simultaneously. When the liquid is just completely absorbed, i.e., when there is no white reflection on the surface, record it as the first absorption rate T1. At 2 minutes, measure the diffusion length and width of the surface layer with the stopwatch and record them.

[0072] Step 4: When the stopwatch reaches 5 minutes, reset it to zero. Repeat steps 2 and 3. After the second absorption is completed, the stopwatch does not need to be reset to zero. Record the second absorption speed as T2.

[0073] Step 5: 5 minutes after the second liquid addition begins (i.e., when the stopwatch reaches 5 minutes), place filter paper M1 at the center of the sample liquid addition point, and simultaneously place the pressure block (2 blocks, approximately 2.4 kg) overlapping on filter paper M1, and apply pressure for 1 minute.

[0074] Step 6: After pressurization is completed, weigh the filter paper and record the weight as M3, and weigh the filter paper at the bottom of the sample and record the weight as M4.

[0075] The parameters obtained using the above method can be used to calculate the product's reabsorption rate (unit: g). The specific calculation process is as follows:

[0076] Re-infiltration amount = M3 - M1

[0077] Leakage amount = M4 - M2.

[0078] Combination Figures 1 to 3The disposable hygiene product shown includes an upper structure 001, an absorbent layer 13, and a lower structure 14. The absorbent layer 13 can be the aforementioned composite core 7. The upper structure 001 and the lower structure 14 can be located on the upper and lower sides of the absorbent layer 13. The upper structure 001, absorbent layer 13, and lower structure 14 are combined to form a whole (i.e., a disposable hygiene product).

[0079] The upper structure 001 includes a three-dimensional protective enclosure 1 and a surface layer 25. The surface layer 25 can be formed by bonding an upper non-woven fabric 5 and a lower non-woven fabric 6 through an ultrasonic process or a hot-pressing process, either online or offline. The surface layer 25 can have a three-dimensional 3D structure. The three-dimensional protective enclosure 1 is provided with a first elastic band 2, and the three-dimensional protective enclosure 1 is also provided with a second elastic band 16 on the left and right sides. The rear end of the upper structure 001 is the back waist part of the disposable sanitary product, and the back waist part is provided with an elastic waistband 15.

[0080] The lower structure 14 may include a bottom nonwoven fabric 9 and a bottom film 8 arranged from bottom to top.

[0081] The width of the upper nonwoven fabric 5 can be less than or equal to the width of the lower nonwoven fabric 6.

[0082] The denier of the first elastic band 2 can be 120D to 1000D, and is preferably 620D.

[0083] The denier of the second elastic band 16 can be 120D to 1000D, and is preferably 620D.

[0084] Waist stickers 3 can be added to the left and right sides of the above-mentioned three-dimensional protective fence 1, and the waist stickers 3 are equipped with magic hooks 4.

[0085] The aforementioned elastic waistband 15 may be composed of a water-repellent nonwoven fabric 11 and a third elastic band 12.

[0086] The aforementioned surface layer 25 can be partitioned embossed, with the number of partitions being greater than or equal to 2, preferably 3 different partitions. For example... Figure 11 and Figure 12As shown, when surface layer 25 includes three different zones, these three zones are the middle zone I1, the left zone I2, and the right zone I3. The embossed dots in the middle zone I1 are gradient dots, decreasing gradually from the center line of the surface layer to both sides. The number of gradient dots is greater than or equal to two, preferably four. The first and second rows of embossed dots are staggered or aligned, preferably staggered. The first row can have a total of nine embossed dots, and the second row can have a total of ten embossed dots. The length L1 and width W1 of the next gradient dot are 30% to 98% of the length L1 and width W1 of the previous dot. The L1*W1 dimensions for point 1 can be 7.4mm*5.3mm, for point 2 it can be 6.7mm*4.8mm, for point 3 it can be 6.1mm*4.4mm, for point 4 it can be 5.5mm*3.9mm, and for point 5 it can be 4.9mm*3.5mm. The patterns for different sections can be the same or different.

[0087] By using zoned pressure points and varying embossing sizes, the liquid can be accelerated to diffuse to both sides, while the zoning also acts as a barrier to the liquid. When the pressure points in the middle region I1 are gradually varied, the side cross-sectional view of its surface layer 25 is as follows. Figure 12 As shown, the pressure points decrease progressively from the central pressure point outwards, resulting in pressure points of varying sizes and heights. This helps the liquid diffuse outwards. Furthermore, the surface layer is divided into sections with embossing. The central region I1 differs from the left region I2 and the right region I3. The pressure point heights of the left region I2 and the right region I3 are greater than or equal to the height of the central pressure point of the central region I1. This creates a dam-like structure in the two outer regions (left region I2 and right region I3), blocking the liquid and preventing side leakage. Figure 12 As indicated by the middle arrow P1.

[0088] The absorbent layer 13 mentioned above can also be composed of a single or multiple combinations of wood pulp core, composite core, absorbent paper, dust-free paper, etc.

[0089] A front waist patch nonwoven fabric 10 can be added below the aforementioned bottom nonwoven fabric 9. This front waist patch nonwoven fabric 10 can be positioned to correspond to the user's abdomen. The front waist patch nonwoven fabric 10 is correspondingly positioned with the Velcro hook 4.

[0090] This example only illustrates the relevant structure of baby diapers.

[0091] The aforementioned surface layer structure design and novel core can also be applied to products such as baby pull-up diapers, adult diapers, adult pull-up pants, women's menstrual pants, and feminine hygiene products.

[0092] The aforementioned undisclosed matters can be directly implemented using existing technologies, so they will not be elaborated upon here.

[0093] Although the present invention has been described above with reference to embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the present invention. In particular, as long as there is no structural conflict, the features in the embodiments disclosed in this invention can be combined with each other in any way. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An irregularly shaped core, characterized in that, It includes a composite core, which includes an intermediate core layer. The two sides of the intermediate core layer have regular and / or irregular shapes. The regular shapes include wavy, triangular, and square shapes.

2. The irregularly shaped core according to claim 1, characterized in that, The regular shape is wavy, and after irregular cutting, a wavy line is formed. The wavy line satisfies the following formula. In the formula for Wave height at location, The height of the wave crest. The distance between the wave crests. The total length of the wavy line. The number of peaks, To observe the altitude, for , This indicates the location of the first peak. The formula satisfied by the wave line simplifies to: 。 3. The irregularly shaped core according to claim 2, characterized in that, The peak height The wave crest spacing is 5% to 45% of the total width W of the composite core. The total length of the wavy line 1% to 100%, number of crests greater than or equal to 1, total length of wavy lines It is 10% to 100% of the total length of the composite core.

4. The irregularly shaped core according to claim 1, characterized in that, The two sides of the intermediate core layer are not wavy, and the transverse cutting depth is... The distance between two adjacent protrusions on one side of the intermediate core layer is 5% to 45% of the total width W of the composite core. Total cutting length 1%~100%, the number of protrusions on one side of the intermediate core layer is greater than or equal to 1, and the total cutting length It is 10% to 100% of the total length of the composite core.

5. The irregularly shaped core according to claim 1, characterized in that, The intermediate core layer includes a lower layer of hydrophilic nonwoven fabric, a first loose fabric, a second loose fabric, and an upper layer of hydrophilic nonwoven fabric arranged sequentially from bottom to top. Both the first and second loose fabrics are sprinkled with superabsorbent polymer resin, which is evenly distributed in the pores of the first and second loose fabrics.

6. The irregularly shaped core according to claim 5, characterized in that, The superabsorbent polymer is evenly distributed on the corresponding first and second tufted fabrics, and / or evenly distributed in the pores on both sides of the first and second tufted fabrics. The composite core also includes a hydrophilic covering fabric disposed on the outside of the central core layer; The two sides of the intermediate core layer are irregularly cut to form a cut area and an uncut area. The hydrophilic covering fabric corresponding to the cut area includes an upper covering layer and a lower covering layer. The upper covering layer and the lower covering layer on both sides of the intermediate core layer are either bonded and sealed or not sealed.

7. A disposable hygiene product, characterized in that, Includes the irregular core as described in any one of claims 1 to 6.

8. The disposable hygiene product according to claim 7, characterized in that, Disposable hygiene products include an upper structure, an absorbent layer, and a lower structure. The absorbent layer is a composite core, and the upper and lower structures are located on the upper and lower sides of the absorbent layer. The upper structure, absorbent layer, and lower structure are combined to form a whole.

9. The disposable hygiene product according to claim 8, characterized in that, The upper structure includes a three-dimensional protective enclosure and a surface layer. The surface layer includes an upper non-woven fabric layer and a lower non-woven fabric layer. A first elastic band is provided inside the three-dimensional protective enclosure, and a second elastic band is provided on the left and right sides of the three-dimensional protective enclosure. The rear end of the upper structure is the back waist part of the disposable sanitary product, and the back waist part is provided with an elastic waistband. The width of the upper non-woven fabric layer is less than or equal to the width of the lower non-woven fabric layer. The lower structure includes a bottom nonwoven fabric and a bottom film arranged from bottom to top; The surface layer is divided into sections with embossing, and the number of sections is greater than or equal to 2.

10. The disposable hygiene product according to claim 9, characterized in that, The surface layer includes at least three different sections. The middle section is called the middle area. The embossing points in the middle area are gradient points, which gradually decrease from the center line of the surface layer to both sides. The first and second rows of embossing points are staggered or aligned. The height of the embossing points in the areas on both sides of the middle area is greater than or equal to the height of the center embossing point of the middle area, so that the surface layer forms a structure that is low in the middle and high on both sides. The number of gradient points is greater than or equal to 2, and the length L1 and width W1 of the next gradient point are 30% to 98% of the length L1 and width W1 of the previous point.

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