Production process of a wrap-around elastic baby diaper

Abstract

This invention relates to the field of disposable hygiene products, specifically to a manufacturing process for a wraparound elastic baby diaper, comprising the following steps: a) preparing the diaper body; b) preparing the elastic waistband, wherein step b includes: b1) taking a continuously conveyed waistband nonwoven fabric, and conveying a plurality of elastic yarns in the same direction on its upper or lower surface, the number of elastic yarns being n, the elastic yarns being ultrasonically welded at equal intervals on the waistband nonwoven fabric, the interval being D1, which is equal to the transverse spacing of the diaper body; the elastic yarns are selected from 30-50 dtex yarns, and the number is 30-45, 55-65, 75-145, 155-200, or 210-350 yarns; b2) applying the product obtained in b1 between the liquid-permeable surface layer and the liquid-impermeable bottom layer in step a4 above, specifically located at both ends of the longitudinal direction of the diaper body and extending transversely along it. This invention solves the problem of insufficient waistband comfort in existing diaper products.

Description

Technical Field

[0001] This invention relates to the field of disposable hygiene products, and more specifically to a manufacturing process for a wraparound elastic baby diaper. Background Technology

[0002] With the improvement of living standards, people are paying more and more attention to personal hygiene. As an essential hygiene product for newborns, baby diapers are receiving increasing attention from consumers regarding their softness, dryness, and absorption speed. Pull-up diapers, or toddler diapers, are gaining popularity due to their convenience and ease of use. Originally designed for toddlers learning to walk, their ease of use has led to their widespread adoption as a regular diaper. Their elastic waistband prevents slippage compared to traditional Velcro diapers, making them more appealing. However, traditional pull-up diapers often have a waistband made of 10 to 20, or even 30 spandex threads bonded to a non-woven fabric using hot-melt adhesive. This results in a thick waistband that often leaves marks on the baby's waist. Therefore, developing a soft, comfortable, and seamless pull-up diaper is crucial. Summary of the Invention

[0003] Therefore, the present invention provides a manufacturing process for a wraparound elastic baby diaper, which solves the problem of insufficient waist comfort in existing diaper products.

[0004] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0005] A manufacturing process for a wraparound elastic baby diaper includes the following steps:

[0006] a. Preparing a diaper body, wherein the diaper body has a longitudinal direction along its length and a transverse direction perpendicular to the longitudinal direction, step a includes:

[0007] a1. Preparation of liquid-permeable surface layer: Take a continuously conveyed surface nonwoven fabric, the surface nonwoven fabric is formed by double carding to have a structure of upper surface nonwoven fabric and lower surface layer, the upper surface nonwoven fabric is formed by carding 0.8-1.2D fine denier fibers and pure cotton fibers, and the lower surface layer is formed by carding 2.5-7D coarse denier fibers;

[0008] a2. Preparation of the absorber core;

[0009] a3. Prepare an impermeable liquid bottom layer;

[0010] a4. Stack and fix the products obtained in steps a1, a2 and a3, fold and cut them to form individual diaper products;

[0011] b. Preparing the elastic waistband, step b includes:

[0012] b1. Take a continuously conveyed waistband nonwoven fabric and convey a number of elastic yarns in the same direction on its upper or lower surface. The number of elastic yarns is n. The elastic yarns are ultrasonically welded to the waistband nonwoven fabric at equal intervals. The interval is D1, which is the same as the lateral interval of the diaper body.

[0013] The elastic yarn is selected from 30-50 dtex yarn, and its number is 30-45, 55-65, 75-145, 155-200 or 210-350;

[0014] b2. The product obtained in b1 is applied between the liquid-permeable surface layer and the liquid-impermeable bottom layer in step a4 above, specifically located at both ends of the longitudinal direction of the diaper body and extending laterally thereafter.

[0015] Preferably, the number of elastic yarns welded to the waistband nonwoven fabric in b1 is n / 2;

[0016] Step b further includes step b11, which is as follows: Take a continuously conveyed waist nonwoven fabric II, and convey n / 2 elastic yarns in the same direction on its upper or lower surface. The elastic yarns are ultrasonically welded to the waist nonwoven fabric II at equal intervals, the interval being D1. Then, the product obtained in step b1 is combined with the product obtained in step b11, and the elastic yarns of step b1 and b11 are sandwiched between the waist nonwoven fabric I and the waist nonwoven fabric II, and are in the same plane.

[0017] Preferably, in steps b1 and b11, the elastic yarn is gathered by the unwinding device into a yarn gathering mechanism. The yarn gathering mechanism includes a frame, an inlet plate and an outlet plate on the frame, and an adjusting roller between the inlet plate and the outlet plate. The inlet plate and the outlet plate are provided with an equal number of yarn holes for the elastic yarn to pass through / out. The two ends of the adjusting roller are mounted on an elastic support. Multiple guide rings for contacting and guiding each elastic yarn are arranged around the adjusting roller. After being gathered by the inlet plate, the elastic yarn is supported in the guide rings on the adjusting roller and then passes through the outlet plate.

[0018] Preferably, the elastic support includes a fixed seat with a bearing for supporting the axial end of the adjusting roller, a telescopic rod located at the lower end of the fixed seat, and a buffer spring sleeved on the outer surface of the telescopic rod and fixedly connected to the lower end of the fixed seat.

[0019] Preferably, in step b2 above, the number of elastic yarns on the product obtained at both ends of the longitudinal direction of the diaper body (b1) is different.

[0020] Preferably, the diaper body is defined to have a front waist area, a crotch area, and a back waist area when worn by a human body, and the dtex value of the elastic yarn of the product b1 located in the front waist area is smaller than that of the product b1 located in the back waist area.

[0021] Preferably, in step b2 above, the elastic yarn density on the product obtained at both ends of the longitudinal direction of the diaper body (b1) is different. Here, density refers to the number of elastic yarns per unit area.

[0022] Preferably, the diaper body is defined to have a front waist area, a crotch area, and a back waist area when worn by a human body, and the density of the elastic yarn of the product b1 located in the front waist area is less than that of the product b1 located in the back waist area.

[0023] Preferably, in step a1 above, a fast-penetrating hydrophilic oil agent is sprayed on one side of the upper surface nonwoven fabric of the surface layer, and a diffusing hydrophilic oil agent is sprayed on the lower surface layer.

[0024] Preferably, the first and second waistband nonwoven fabrics are made of hot-air nonwoven fabric or spunbond nonwoven fabric.

[0025] By adopting the aforementioned technical solution, the beneficial effects of the present invention are:

[0026] This invention addresses the shortcomings of current disposable diaper elastic waistbands, such as their bulkiness and tendency to leave marks. It specifically improves the production line design by using multiple strands of finer elastic yarns to avoid the traditional use of thicker spandex yarns. Unlike traditional production lines, these multiple strands of fine elastic yarns are numerous, have low elasticity, and are prone to breakage. Therefore, they cannot be transported using traditional elastic band feeding equipment. This invention employs an off-line, decelerated, and independent production method for the elastic waistbands before combining them with the diaper body. This significantly reduces the probability of fine elastic yarn breakage during production. Compared to online production, the probability of defective diapers is lower, the tolerance for error is higher, and the waste cost is lower.

[0027] The production of elastic waistbands can be carried out independently outside the production line, which makes it easier to adjust the production line. When there are many strands, the feeding and unwinding equipment of elastic yarn can be separated from the production line, which is beneficial for the initial equipment layout and also facilitates the addition and maintenance in the later stages.

[0028] In terms of materials, the waistband non-woven fabric is made of hot air non-woven fabric or spunbond non-woven fabric, which ensures the softness of the elastic waistband. Ultrasonic point pressing composite is used in production, and no elastic is used in the waistband, which reduces the thickness of the elastic waistband. The product does not feel heavy in the waistband area, and is soft and thin. It will not leave marks after use.

[0029] The liquid-permeable surface layer is produced using a double-carding process, forming a skin-friendly and flexible upper non-woven fabric. It is made of fine denier fibers combined with pure cotton fibers and contains a fast-penetrating hydrophilic oil agent to ensure comfort on the side closest to the skin. The lower non-woven fabric is made of coarse denier fibers with large gaps between the fibers. Combined with a diffusion hydrophilic oil agent, it can quickly diffuse the liquid that has permeated from the upper non-woven fabric. Structurally, it forms a skin-friendly outer layer and a highly diffusive inner layer. Combined with an elastic waistband, the product is soft and thin overall, and compared with traditional diapers, the waistband is comfortable and imperceptible. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the unfolded structure of a diaper according to Embodiment 1 of the present invention;

[0031] Figure 2 for Figure 1 Schematic diagram of the cross-sectional structure along the AA direction;

[0032] Figure 3 This is a schematic diagram of the molding process in Embodiment 1 of the present invention;

[0033] Figure 4 This is a schematic diagram of the structure of the hub mechanism according to Embodiment 1 of the present invention;

[0034] Figure 5 for Figure 1 A cross-sectional view of the second embodiment in the AA direction;

[0035] Figure 6 This is a schematic diagram of the molding process of the elastic waistband in Embodiment 2 of the present invention.

[0036] Reference numerals: 1. Liquid-permeable surface layer; 11. Upper surface nonwoven fabric; 12. Lower surface nonwoven fabric; 2. Absorbent core; 3. Liquid-impermeable bottom layer; 4. Elastic waistband; 41. Waistband nonwoven fabric; 41a. Waistband nonwoven fabric one; 41b. Waistband nonwoven fabric two; 42. Elastic yarn; 5. Guide layer; 6. Yarn gathering mechanism; 61. Inlet plate; 62. Outlet plate; 63. Adjusting roller; 631. Guide ring; 64. Elastic bracket; 641. Fixing base; 642. Telescopic rod; 643. Buffer spring. Detailed Implementation

[0037] The following will describe in detail the implementation of the present invention with reference to specific embodiments, so that the process of how the present invention uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0038] Example 1

[0039] refer to Figure 1 and Figure 2A wraparound elastic baby diaper includes a diaper body having a longitudinal direction along its length and a transverse direction perpendicular to the longitudinal direction. The diaper body includes a liquid-permeable top layer 1, an absorbent core 2, and a liquid-impermeable bottom layer 3 stacked together. A guide layer 5 is provided between the liquid-permeable top layer 1 and the absorbent core 2. Elastic waistbands 4 extending transversely are provided at both ends of the longitudinal direction of the diaper body. The elastic waistbands 4 are sandwiched between the liquid-permeable top layer 1 and the liquid-impermeable bottom layer 3. The elastic waistbands 4 include a waistband nonwoven fabric 41 and a plurality of evenly distributed elastic yarns 42 welded to the waistband nonwoven fabric 41. The elastic yarns 42 are selected from 30-50 dtex yarns. The selection of elastic yarn 42 models is not detailed here, as different product lines may use any model included in this category.

[0040] The liquid-permeable surface layer 1 consists of an upper nonwoven fabric 11 and a lower nonwoven fabric 12. The upper nonwoven fabric 11 is formed by carding 0.8-1.2D fine denier fibers with pure cotton fibers, and the lower nonwoven fabric 12 is formed by carding 2.5-7D coarse denier fibers. In this technical solution, the upper nonwoven fabric 11 is made by carding a mixture of 1.0D fibers with cotton fibers. Specifically, the fine denier fibers are selected from fibers such as Tencel or silk, which are silky, soft, and skin-friendly. Furthermore, as the side closest to the skin, additives can be sprayed or roller-coated onto the upper nonwoven fabric 11 to give it antibacterial, skin-protecting, and odor-reducing effects.

[0041] The double-carding process of the upper nonwoven fabric 11 and the lower nonwoven fabric 12 is common knowledge, and details can be found in Chinese patent application CN107059246A, which will not be elaborated here. The liquid-permeable surface layer 1 is produced using a double-carding process to form a skin-friendly and flexible upper nonwoven fabric 11, which is made of fine denier fibers combined with pure cotton fibers and has a fast-penetrating hydrophilic oil agent added to ensure comfort on the side closest to the human skin; while the lower nonwoven fabric 12 is made of coarse denier fibers, specifically 5D or 7D fibers, with large gaps between the fibers. Combined with a diffusion hydrophilic oil agent, it can quickly diffuse the liquid that permeates from the upper nonwoven fabric 11; structurally, it forms a structure with a skin-friendly outer layer and a highly diffusive inner layer. Structurally, the lower nonwoven fabric 12 is coated with a diffusion hydrophilic agent layer. The rapidly penetrating hydrophilic oil agent and the diffusion hydrophilic agent layer are liquid film cracking agents as shown in Chinese Patent CN109196162B, and their components are as shown therein; and their coating method, or setting method, is as shown in CN109219679B, which will not be described in detail here.

[0042] The aforementioned liquid-permeable surface layer 1, combined with the elastic waistband 4, enables the product to be soft and thin overall, and compared with traditional diapers, the waistband is comfortable and imperceptible.

[0043] The unit "D" here specifically refers to Denier, a unit of density, which is the weight in grams of 9,000 meters of yarn or fiber; dtex, short for dtex, refers to the weight in grams of 10,000 meters of yarn at standard moisture regain.

[0044] Preferably, the elastic yarn 42 can be a 35-45 dtex yarn to be suitable for the production of most product models.

[0045] Structurally, the elastic yarn 42 is ultrasonically welded to the waistband nonwoven fabric 41, and the transverse sides of the waistband nonwoven fabric 41 are hot-pressed or ultrasonically welded between the liquid-permeable surface layer 1 and the liquid-impermeable bottom layer 3. The elastic yarn 42 is uniformly fixed to the waistband area along the waistband direction by hot pressing or ultrasonic welding, fixing both ends of the elastic yarn 42 while fixing the composite waistband, so that the elastic yarn 42 has a fixed stretch ratio.

[0046] In terms of material selection, the waistband nonwoven fabric 41 is made of hot-air nonwoven fabric or spunbond nonwoven fabric to meet the requirements of softness.

[0047] Structurally, the number of elastic yarns 42 is 30-45, 55-65, 75-145, 155-200, or 210-350. This number can be set according to different yarn types, product size and model, product characteristics, and target audience (e.g., adults, infants, newborns), thus offering different options.

[0048] To facilitate production, the waistband nonwoven fabric 41 is composed of two layers, with the elastic yarn 42 welded between the two layers. Currently, the elastic waistband 4 is produced separately off-line. The elastic yarn 42 can be applied to the waistband nonwoven fabric 41 in batches before the two layers of waistband nonwoven fabric 41 are laminated to form an elastic waistband 4 with a larger number of elastic yarns 42, thus reducing production difficulty. The elastic waistband 4 is then laminated into the overall diaper product after molding.

[0049] A manufacturing process for a wraparound elastic baby diaper includes the following steps:

[0050] a. Preparing a diaper body, wherein the diaper body has a longitudinal direction along its length and a transverse direction perpendicular to the longitudinal direction, step a includes:

[0051] a1. Preparation of liquid-permeable surface layer 1: Take a continuously conveyed surface nonwoven fabric, the surface nonwoven fabric is formed by double carding to have a structure of upper surface nonwoven fabric 11 and lower surface layer, the upper surface nonwoven fabric 11 is formed by carding 0.8-1.2D fine denier fibers and pure cotton fibers, the lower surface layer is formed by carding 2.5-7D coarse denier fibers;

[0052] a2. Preparation of absorber core 2;

[0053] a3. Preparation of an impermeable liquid bottom layer 3;

[0054] a4. Stack and fix the products obtained in steps a1, a2 and a3, fold and cut them to form individual diaper products;

[0055] b. Preparing the elastic waistband 4, step b includes:

[0056] b1. Take a continuously conveyed waist non-woven fabric 41a, and convey a number of elastic yarns 42 in the same direction on its lower surface. The number of elastic yarns 42 is n. The elastic yarns 42 are ultrasonically welded to the waist non-woven fabric 41a at equal intervals. The interval is D1, which is the same as the lateral interval of the diaper body.

[0057] The elastic yarn 42 is selected from 30-50 dtex yarn, and its number is 30-45, 55-65, 75-145, 155-200 or 210-350.

[0058] b2. The product obtained in b1 is applied between the liquid-permeable surface layer 1 and the liquid-impermeable bottom layer 3 in step a4 above, specifically located at both ends of the longitudinal direction of the diaper body and extending laterally thereafter.

[0059] This invention addresses the shortcomings of current diaper elastic waistbands 4, such as being thick and prone to leaving marks. It specifically improves the production line design by using multiple strands of finer elastic yarn 42 to avoid the traditional use of thicker spandex yarn. Unlike traditional production lines, the multiple strands of fine elastic yarn 42 are numerous, have low elasticity, and are easily broken. Therefore, they cannot be transported using traditional elastic band feeding equipment. This invention employs an off-line, decelerated, and independently produced elastic waistband 4 before being combined with the diaper body. This significantly reduces the probability of fine elastic yarn 42 breaking during production. Compared to online production, the probability of defective diapers is lower, the error tolerance is higher, and the waste cost is lower.

[0060] The production of elastic waistband 4 is carried out independently outside the production line, which makes it easier to adjust the production line. When there are many strands, the feeding and unwinding equipment of elastic yarn 42 can be separated from the production line, which is beneficial for the initial equipment layout and also facilitates the addition and maintenance in the later stages.

[0061] In this embodiment, in steps b1 and b11, the elastic yarn 42 is gathered by the unwinding device into a yarn collecting mechanism 6, as detailed in the following reference. Figure 4The elastic yarns 42 are numerous, and their unwinding equipment is several times larger than that of conventional production. Therefore, the yarn gathering mechanism 6 needs to be designed to gather and adjust the elastic yarns 42. The yarn gathering mechanism 6 includes a frame, an inlet plate 61 and an outlet plate 62 mounted on the frame, and an adjusting roller 63 located between the inlet plate 61 and the outlet plate 62. The inlet plate 61 and the outlet plate 62 are provided with an equal number of thread holes for the elastic yarns 42 to pass through / exit. The adjusting roller 63 is mounted on an elastic support 64 at both ends. The adjusting roller 63 is surrounded by multiple guide rings 631 for contact and guidance of each elastic yarn 42. Specifically, the guide rings 631 are made of ceramic or metal and are detachable, which can be easily disassembled or added or removed. After being gathered by the inlet plate 61, the elastic yarns 42 are supported in the guide rings 631 on the adjusting roller 63 and then pass out of the outlet plate 62. During production, the elastic yarns 42 are collected by various unwinding devices and pass through the infeed plate 61. Then, the direction is adjusted on the infeed plate 61, and the yarns are mounted on the adjusting roller 63. During transmission, the elastic support 64 of the adjusting roller 63 actively generates irregular up-and-down elastic feedback under the force of each elastic yarn 42, thereby achieving the purpose of adjusting the elastic yarns 42. In this process, the elastic force generated by the elastic yarns 42 varies depending on the position of the unwinding devices and the placement of the elastic yarns 42. Therefore, the adjusting roller 63 is needed to uniformly adjust them, ensuring that the elastic yarns 42 after passing through the exit plate 62 have a relatively uniform elasticity. This avoids inconsistent elasticity after lamination and also prevents individual elastic yarns 42 from breaking during transport.

[0062] Specifically, the elastic support 64 includes a fixed seat 641 with a bearing for supporting the axial end of the adjusting roller 63, a telescopic rod 642 located at the lower end of the fixed seat 641, and a buffer spring 643 sleeved on the outer surface of the telescopic rod 642 and fixedly connected to the lower end of the fixed seat 641. Structurally, the telescopic rod 642 is supported by the buffer spring 643, and when subjected to force during production, the buffer spring 643 can actively achieve elastic adjustment.

[0063] Meanwhile, depending on the product's positioning, size, and target audience, the elastic waist circumference 4 can also be adjusted for its specific elasticity during production through the following methods:

[0064] First, in step b2 above, the number of elastic yarns 42 on the products obtained in b1 at both ends of the longitudinal direction of the diaper body is different. Specifically, the diaper body is defined to have a front waist area, a crotch area, and a back waist area when worn by a human. The dtex value of the elastic yarns 42 on the product obtained in b1 on the front waist area is smaller than that on the product obtained in b1 on the back waist area. At this time, when the number of elastic yarns 42 in the front waist area and the back waist area is the same, the dtex value of the front waist area is chosen to be smaller, so that the elasticity of the back waist area is greater than that of the front waist area, in order to meet the actual wearing needs of the human body.

[0065] Second, in step b2 above, the elastic yarns 42 on the products obtained at both ends of the longitudinal direction of the diaper body (b1) have different densities. Here, density refers to the number of elastic yarns 42 per unit area. Specifically, the diaper body is defined as having a front waist area, a crotch area, and a back waist area when worn by a person. The density of the elastic yarns 42 on the product obtained at the front waist area (b1) is less than that on the product obtained at the back waist area (b1). In this case, the elasticity of the elastic waistband 4 is adjusted by adjusting the number of elastic yarns 42 to achieve the purpose of different elasticity between the front and back waist areas.

[0066] The above only shows two specific choices of the type and number of elastic yarns 42 in the front waist area and the back waist area under normal conditions. When the target audience is different, it can also be designed with the above specific choices, with multiple combinations, which will not be elaborated here.

[0067] In production, in step a1 above, a fast-penetrating hydrophilic oil agent is sprayed onto one side of the upper surface layer nonwoven fabric 11 of the surface layer, and a diffusing hydrophilic oil agent is sprayed onto the lower surface layer. This process is carried out during continuous conveying after the liquid-permeable surface layer 1 is formed, and different oil agents are sprayed onto its upper and lower surfaces respectively, so that the upper and lower surfaces of the liquid-permeable surface layer 1 achieve the required technical effect.

[0068] Example 2

[0069] refer to Figure 5 , Figure 6 Compared with Example 1, the number of elastic yarns 42 welded to the waist nonwoven fabric 41a in b1 is n / 2;

[0070] Step b further includes step b11, which involves: taking a continuously conveyed waist nonwoven fabric 41b, and conveying n / 2 elastic yarns 42 in the same direction on its upper or lower surface. The elastic yarns 42 are ultrasonically welded to the waist nonwoven fabric 41b at equal intervals, the interval being D1. Then, the product obtained in step b1 is combined with the product obtained in step b11, and the elastic yarns 42 of steps b1 and b11 are sandwiched between the waist nonwoven fabric 41a and the waist nonwoven fabric 41b, in the same plane. During production, it is necessary to adjust the spacing and position of the elastic yarns 42 on the waist nonwoven fabric 41a and the waist nonwoven fabric 41b to ensure that there is no large overlap after the two are combined.

[0071] This structural design changes the original one-time molding of the elastic waistband 4 to two moldings, which is particularly suitable for situations where the number of elastic yarns 42 is large. Under this structure, the two-time lamination of elastic yarns 42 can greatly reduce the lamination difficulty and has good practicality in production.

[0072] Specifically, the waistband nonwoven fabric 41a and waistband nonwoven fabric 41b are made of hot-air nonwoven fabric or spunbond nonwoven fabric, and the materials can meet the product's requirements for softness.

[0073] Although the invention has been specifically shown and described in conjunction with preferred embodiments, those skilled in the art should understand that various changes in form and detail may be made to the invention without departing from the spirit and scope of the invention as defined in the appended claims, all of which shall be within the scope of protection of the invention.

Claims

1. A manufacturing process for a wraparound elastic baby diaper, characterized in that, Includes the following steps: a. Preparing a diaper body, wherein the diaper body has a longitudinal direction along its length and a transverse direction perpendicular to the longitudinal direction, step a includes: a1. Preparation of liquid-permeable surface layer (1): Take a continuously conveyed surface nonwoven fabric, the surface nonwoven fabric is formed by double carding and has a structure of upper surface nonwoven fabric (11) and lower surface layer, the upper surface nonwoven fabric (11) is formed by carding 0.8-1.2D fine denier fibers and pure cotton fibers, and the lower surface layer is formed by carding 2.5-7D coarse denier fibers; a2. Preparation of the absorber core (2); a3. Preparation of an impermeable liquid bottom layer (3); a4. Stack and fix the products obtained in steps a1, a2 and a3, fold and cut them to form individual diaper products; b. Preparing the elastic waistband (4), step b is an off-line independent production step, and its production speed is lower than that of the diaper body. Step b includes: b1. Take a continuously conveyed waist non-woven fabric (41a) and convey a number of elastic yarns (42) in the same direction on its upper or lower surface. The number of elastic yarns (42) is n. The elastic yarns (42) are ultrasonically welded to the waist non-woven fabric (41a) at equal intervals. The interval is D1, which is the same as the transverse interval of the diaper body. The elastic yarn (42) is selected from 30-50 dtex yarn, and its number is 30-45, 55-65, 75-145, 155-200 or 210-350; b2. The product obtained in b1 is applied between the liquid-permeable surface layer (1) and the liquid-impermeable bottom layer (3) in step a4 above. Specifically, it is located at both ends of the longitudinal direction of the diaper body and extends laterally. The diaper body is defined to have a front waist area, a crotch area and a back waist area when worn by a human body. The elastic waistband has different elastic contraction forces in the front waist area and the back waist area. The number of elastic yarns (42) in b1 welded to the waist nonwoven fabric (41a) is n / 2; Step b further includes step b11, which is as follows: take a continuously conveyed waist nonwoven fabric II (41b), and convey n / 2 elastic yarns (42) in the same direction on its upper or lower surface. The elastic yarns (42) are ultrasonically welded to the waist nonwoven fabric II (41b) at equal intervals, the interval being D1. Then, the product obtained in step b1 is combined with the product obtained in step b11, and the elastic yarns (42) of step b1 and b11 are sandwiched between the waist nonwoven fabric I (41a) and the waist nonwoven fabric II (41b) in the same plane. In steps b1 and b11, the elastic yarn (42) is gathered by the unwinding device into a yarn gathering mechanism (6). The yarn gathering mechanism (6) includes a frame, an inlet plate (61) and an outlet plate (62) on the frame, and an adjusting roller (63) between the inlet plate (61) and the outlet plate (62). The inlet plate (61) and the outlet plate (62) are provided with an equal number of yarn holes for the elastic yarn (42) to pass through / exit. The two ends of the adjusting roller (63) are mounted on an elastic support (64). The adjusting roller (63) is surrounded by multiple guide rings (631) for contact and guidance of each elastic yarn (42). After being gathered by the inlet plate (61), the elastic yarn (42) is supported in each guide ring (631) on the adjusting roller (63) and then passes through the outlet plate (62). The elastic support (64) includes a fixed seat (641) with bearing for supporting the axial end of the adjusting roller (63), a telescopic rod (642) provided at the lower end of the fixed seat (641), and a buffer spring (643) sleeved on the outer surface of the telescopic rod (642) and fixedly connected to the lower end of the fixed seat (641). In step b2 above, the number of elastic yarns (42) on the products obtained by b1 at both ends of the longitudinal direction of the diaper body is different; the difference in elastic shrinkage force between the front waist area and the back waist area is achieved by making the dtex value of the elastic yarns (42) of the products obtained by b1 in the front waist area smaller than that of the products obtained by b1 in the back waist area. Alternatively: In step b2 above, the elastic yarns (42) on the products obtained by b1 at both ends of the longitudinal direction of the diaper body have different densities; the difference in elastic contraction force between the front waist area and the back waist area is achieved by making the density of the elastic yarns (42) on the products obtained by b1 in the front waist area less than that on the products obtained by b1 in the back waist area.

2. The manufacturing process of a wraparound elastic baby diaper according to claim 1, characterized in that: In step a1 above, a fast-penetrating hydrophilic oil agent is sprayed on one side of the upper surface nonwoven fabric (11) of the surface nonwoven fabric, and a diffusing hydrophilic oil agent is sprayed on the lower surface side.

3. The manufacturing process of a wraparound elastic baby diaper according to claim 1, characterized in that: The waistband nonwoven fabric one (41a) and waistband nonwoven fabric two (41b) are made of hot air nonwoven fabric or spunbond nonwoven fabric.

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