Production process of anti-tightening underpants

Abstract

The invention provides a production process of anti-tightening underpants, which comprises the following steps: step 1, providing an underpants blank which is a seamless underpants blank or a cut-part type underpants body; 2, a waist opening and leg openings of the underpants blank body are inwards provided with slow pressing edge forming areas; step 3, preparing partitioned extension-limiting elastic adhesive film belts matched with the circumferential directions of the waist opening and the leg openings; step 4, coating a hot melt adhesive on the binding surface of the partition extension-limiting elastic adhesive film belt to form an adhesive layer; step 5, loading the underpants green body on a pretension calibration clamp; step 6, the partitioned stretching-limiting elastic adhesive film belt coated with the adhesive is positioned and attached to the slow-pressing edge forming area, and partitioned hot-pressing bonding is carried out under the assistance of vacuum adsorption or pressure difference; and step 7, after hot pressing, cooling and shaping, and unloading. The method solves the problems mentioned in the background technology.

Description

Technical Field

[0001] This invention relates to the field of clothing, and more particularly to a manufacturing process for anti-binding underwear. Background Technology

[0002] As a frequently worn item worn close to the skin, the comfort of underwear highly depends on the edge structure of the waistband and leg openings. Traditional underwear typically uses elastic bands sewn together, bound, or folded at the edges to achieve restraint and elastic support. However, due to the high modulus of the elastic bands themselves, the thick layers of seam threads, and fluctuations in local sewing tension, it is easy to form obvious marks on the skin and cause friction and irritation when walking or sitting for a long time. At the same time, the many sewing processes and narrow process window make it easier for the size and tightness of the same batch to be inconsistent due to differences in sewing tension and elastic rebound during mass production, which further amplifies the problems of "tightness" and "localized pressure concentration".

[0003] In recent years, the trend towards seamless fabrics has driven the industry to experiment with adhesive film bonding to replace some stitching, especially at waistbands and leg openings, to improve smoothness and reduce seam marks. Publicly available solutions point out that traditional elastic bands easily leave marks and propose using adhesive film bonding to improve smoothness and comfort; other processes soften the adhesive film, use vacuum adsorption or pressure difference to bond it, then perform hot pressing at 80℃~90℃ and cool to set, thus achieving a strong bond at the edges. While these approaches can indeed reduce seam protrusions and friction points to some extent, they still have significant shortcomings in terms of consistency between actual wear and mass production, mainly in the following aspects: 1. Many adhesive films or hot-pressing solutions have the same width, thickness, and adhesive strength throughout the entire circumference, resulting in pressure peaks still appearing in areas with different curvatures and soft tissue thicknesses, such as the waist / leg opening, the front abdomen, the hip side, and the lower back. In other words, although the solution has shifted from "suture restraint" to "continuous adhesive film constraint," it has not resolved the fundamental contradiction that "different parts require different constraints."

[0004] 2. If the blank is in an unstable tension state during edge bonding, the rebound after hot pressing will be "solidified and locked", resulting in more obvious passive shrinkage in certain areas when worn, thus creating new pressure points and curling edges; in addition, the thickness of the adhesive layer and insufficient air release may also lead to problems such as bubbling, edge lifting, and reduced washability.

[0005] 3. Even when attempting to soften the material, there is often a lack of quantitative calibration steps for "pre-stretching amount and hot-press curing strength in different circumferential areas", which means that the process can only rely on experience to adjust the machine, making it difficult to guarantee batch stability. Summary of the Invention

[0006] To solve the above-mentioned technical problems, the present invention provides a manufacturing process for anti-binding underwear, which solves the problems mentioned in the background art.

[0007] The manufacturing process for anti-binding underwear provided by this invention includes the following steps: Step 1: Provide an underwear blank, which is a seamless underwear blank or a cut-piece underwear body; Step 2: Set a soft-press edge area inward at the waist and leg openings of the underwear blank; Step 3: Prepare a partitioned stretch-limiting elastic film strip that matches the waist and leg openings in the circumferential direction. The partitioned stretch-limiting elastic film strip includes at least a first functional segment and a second functional segment in the circumferential direction, and the equivalent elastic constraint of the second functional segment is less than that of the first functional segment. Step 4: Apply hot melt adhesive to the bonding surface of the partitioned stretchable elastic film tape to form an adhesive layer; Step 5: Load the underwear blank onto the pretension calibration fixture, and apply different pretension rates to the corresponding positions of different functional sections along the circumferential direction, so that the pretension rate of the corresponding position of the second functional section is less than the pretension rate of the corresponding position of the first functional section. Step 6: Position and bond the coated partitioned stretch elastic film tape to the slow-pressed edge area, and perform partitioned hot-press bonding under vacuum adsorption or pressure difference assistance, and the hot-press curing parameters corresponding to the second functional segment are lower than the hot-press curing parameters corresponding to the first functional segment. Step 7: After hot pressing, cool and shape the product and remove the clamps to obtain the finished anti-binding underwear with zoned elasticity differences at the waist and leg openings.

[0008] Preferably, after step S1, the underwear blank is subjected to low-tension pre-shrinking treatment, which is steam pre-shrinking, with a pre-shrinking temperature of 75-85°C and a pre-shrinking time of 20-35 minutes.

[0009] Preferably, the partitioned stretchable elastic film strip is divided into at least three sections along the circumferential direction: a front section, a side section, and a rear section, wherein the side section is the second functional section; Furthermore, the side segment must satisfy at least one of the following conditions compared to the front and rear segments: smaller width, thinner thickness, or higher micropore density, in order to reduce the equivalent elastic constraint of the side segment.

[0010] Preferably, the partitioned stretch-limiting elastic film tape has stress-relieving microstructures near the skin-contact edge. The stress-relieving microstructures are micropore arrays and micro-cut arrays, wherein the micropore diameter is 0.3-0.8 mm, the pore spacing is 1.5-4 mm, and 1-3 rows are arranged circumferentially.

[0011] Preferably, the hot melt adhesive in step S4 is PUR hot melt adhesive or polyurethane hot melt adhesive, and intermittent adhesive application or reduced adhesive application per unit area is used in the second functional section, while continuous adhesive application or increased adhesive application per unit area is used in the first functional section. After adhesive application, the adhesive film is pre-cured and dried at a temperature of 50-70°C for 10-15 minutes.

[0012] Preferably, in step S5, the pre-stretch rate satisfies the following conditions: the pre-stretch rate at the position corresponding to the second functional segment is 2% to 6%, and the pre-stretch rate at the position corresponding to the first functional segment is 6% to 12%.

[0013] Preferably, step S6 employs a two-stage partitioned hot-pressing curve: The pre-bonding section temperature is 75–85℃, the pressure is 0.15–0.30 MPa, and the time is 8–20 seconds; The curing section temperature is 85–95℃, the pressure is 0.25–0.45MPa, and the time is 10–35s; Furthermore, the curing pressure and time of the second functional stage are reduced by 10% to 30% compared to the first functional stage; In step S7, during cooling and shaping, maintain a light pressure of 0.05–0.15 MPa for 60–180 seconds.

[0014] The beneficial effects of this invention are: 1. Significantly reduces chafing marks and tightness: The first / second functional sections are set by dividing the elastic film tape into sections, and the second functional section has a smaller equivalent elastic constraint. At the same time, the stress relief structure with micro-holes / micro-cuts on the side sections generates lower rebound constraint in sensitive areas such as waist and leg openings, thereby reducing the probability of local pressure peaks and chafing marks.

[0015] 2. Create repeatable zoned rebound differences for better mass production consistency: Introduce pre-tension calibration fixtures and apply different pre-tension rates to different functional sections, and then add zoned hot-press curing parameter differences, so that zoned anti-squeezing no longer depends on subjective feel, but is controlled by quantifiable parameters, resulting in smaller batch fluctuations.

[0016] 3. More stable adhesion and smoother edges: Vacuum adsorption or pressure difference assisted bonding and two-stage hot pressing are used, which is conducive to air removal and reduces air bubbles and edge curling; the cooling stage maintains light pressure for shaping, which helps to reduce edge curling caused by springback after hot pressing. Attached Figure Description

[0017] Figure 1 The production process flow diagram of the anti-binding underwear provided by the present invention; Figure 2 This is a schematic diagram of the structure of the partitioned stretch-limiting elastic film tape provided by the present invention; Figure 3 This is a schematic diagram of the partitioned hot-press bonding provided by the present invention.

[0018] The diagram is labeled as follows: 1. Front section; 2. Side section; 3. Rear section; 4. Hot press head; 5. First functional section; 6. Second functional section; 7. Slow-press edge area. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] Please refer to the following: Figure 1 , Figure 2 as well as Figure 3 ,in Figure 1 The production process flow diagram of the anti-binding underwear provided by the present invention; Figure 2 This is a schematic diagram of the structure of the partitioned stretch-limiting elastic film tape provided by the present invention; Figure 3 This is a schematic diagram of the partitioned hot-press bonding provided by the present invention.

[0021] In the specific implementation process, such as Figures 1-3 As shown, it includes the following steps: Step 1: Provide an underwear blank, which is a seamless underwear blank or a cut-piece underwear body; Step 2: Set a soft-press edge area inward at the waist and leg openings of the underwear blank; Step 3: Prepare a partitioned stretch-limiting elastic film strip that matches the waist and leg openings in the circumferential direction. The partitioned stretch-limiting elastic film strip includes at least a first functional segment and a second functional segment in the circumferential direction, and the equivalent elastic constraint of the second functional segment is less than that of the first functional segment. Step 4: Apply hot melt adhesive to the bonding surface of the partitioned stretchable elastic film tape to form an adhesive layer; Step 5: Load the underwear blank onto the pretension calibration fixture, and apply different pretension rates to the corresponding positions of different functional sections along the circumferential direction, so that the pretension rate of the corresponding position of the second functional section is less than the pretension rate of the corresponding position of the first functional section. Step 6: Position and bond the coated partitioned stretch elastic film tape to the slow-pressed edge area, and perform partitioned hot-press bonding under vacuum adsorption or pressure difference assistance, and the hot-press curing parameters corresponding to the second functional segment are lower than the hot-press curing parameters corresponding to the first functional segment. Step 7: After hot pressing, cool and shape the product and remove the clamps to obtain the finished anti-binding underwear with zoned elasticity differences at the waist and leg openings.

[0022] Example 1: Production of seamless trouser blanks to prevent binding 1. Billet preparation and pre-shrinking 1.1. Provide underwear blanks, select seamless underwear blanks (cylindrical knitting), and complete basic shaping and inspection.

[0023] 1.2. Perform low-tension steam pre-shrinking on the billet: temperature 75-85℃, time 20-35 minutes, to stabilize the billet dimensions and release residual stress.

[0024] 2. Set up a buffer zone Leave a soft-pressing edge area inward at the waist and leg edges (this area can be achieved by adjusting the weave structure or relaxing it after processing) as a bearing area for adhesive film bonding, reducing the tendency of edge hardening and curling.

[0025] 3. Preparation of zoned stretch-limiting elastic adhesive tape 3.1. Prepare adhesive tapes according to the circumferential dimensions of the waist opening and leg opening respectively.

[0026] 3.2. The adhesive tape is divided into three sections along the circumference: front section, side section, and rear section. The side section is designated as the second functional section. The side section is designed to be at least as wide, thinner, or have a higher micropore density than the front / rear section, in order to reduce the equivalent elastic constraint of the side section.

[0027] 3.3. Stress-relieving microstructures are set near the skin-contact edge of the adhesive film: micropore array and micro-cut array; micropore diameter 0.3-0.8mm, pore spacing 1.5-4mm, 1-3 rows along the circumference, to provide local release channels during stretching and reduce pressure peak.

[0028] 4. Applying adhesive and pre-curing drying 4.1. Apply hot melt adhesive to the bonding surface of the adhesive film to form an adhesive layer, wherein the hot melt adhesive is PUR hot melt adhesive or polyurethane hot melt adhesive.

[0029] 4.2. In the second functional section, intermittent glue application or reduced glue application per unit area is adopted, while in the first functional section, continuous glue application or increased glue application per unit area is adopted.

[0030] 4.3. Pre-curing and drying after applying adhesive: 50-70℃, 10-15 minutes.

[0031] 5. Loading of pretension calibration fixture and zoned pretensioning 5.1. Load the underwear blank onto the pretension calibration fixture (the fixture can be a ring support structure with segmented clamping points and scale marks along the circumference to apply different pretension rates to different areas).

[0032] 5.2. Pre-stretch rate applied to the zones: 2% to 6% for the corresponding position of the second functional segment (side segment), and 6% to 12% for the corresponding position of the first functional segment.

[0033] Note: This pretension calibration is used to distribute the elastic reserves of different circumferential areas before hot pressing and curing, so as to avoid localized pressure points caused by the same rebound throughout the entire circle.

[0034] 6. Positioning and bonding with zoned hot pressing 6.1. Position and bond the coated, zoned, stretchable elastic film tape to the edge area, and use vacuum adsorption or pressure difference to assist bonding, so that the film can be more fully degassed and adhered.

[0035] 6.2. A two-stage zoned hot pressing curve is adopted: Pre-bonding section: 75~85℃, 0.15~0.30MPa, 8~20s; Curing section: 85~95℃, 0.25~0.45MPa, 10~35s; This also reduces the pressure and time of the second functional stage curing stage by 10% to 30% compared to the first functional stage.

[0036] Explanation: By using partitioned low-curing strength, the side-section bonding stiffness is lower and more flexible, thus creating circumferential springback differences.

[0037] 7. Cooling, shaping, and clamping After hot pressing, maintain a light pressure of 0.05-0.15 MPa and cool for 60-180 seconds. Then remove the clamps to obtain a finished product with zoned rebound differences between the waist and leg openings.

[0038] Example 2: Production of anti-squeezing trousers with pre-cut panels The difference from Example 1 is that: after the blank is sewn or seamlessly spliced ​​into trousers, the waist and leg openings are then provided with pressure relief zones, partitioned adhesive tapes, and partitioned heat pressing in accordance with claims 1-7.

[0039] Key considerations remain: steam pre-shrinkage at 75–85°C for 20–35 minutes; three-segment structure of the zoned adhesive film with low constraint on the side segments; micropore and micro-cut size range; hot melt adhesive type, zoned application strategy, and pre-curing conditions. The pre-stretching rate for each zone is 2%–6% and 6%–12%; the parameters for the two-stage zoned hot pressing curve and the second functional section are reduced by 10%–30%. This embodiment is more conducive to integration with existing cutting, sewing / seamless splicing processes and is suitable for parallel production of multiple sizes and styles.

[0040] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A manufacturing process for anti-binding underwear, characterized in that, Includes the following steps: Step 1: Provide an underwear blank, which is a seamless underwear blank or a cut-piece underwear body; Step 2: Set a soft-press edge area inward at the waist and leg openings of the underwear blank; Step 3: Prepare a partitioned stretch-limiting elastic film strip that matches the waist and leg openings in the circumferential direction. The partitioned stretch-limiting elastic film strip includes at least a first functional segment and a second functional segment in the circumferential direction, and the equivalent elastic constraint of the second functional segment is less than that of the first functional segment. Step 4: Apply hot melt adhesive to the bonding surface of the partitioned stretchable elastic film tape to form an adhesive layer; Step 5: Load the underwear blank onto the pretension calibration fixture, and apply different pretension rates to the corresponding positions of different functional sections along the circumferential direction, so that the pretension rate of the corresponding position of the second functional section is less than the pretension rate of the corresponding position of the first functional section. Step 6: Position and bond the coated partitioned stretch elastic film tape to the slow-pressed edge area, and perform partitioned hot-press bonding under vacuum adsorption or pressure difference assistance, and the hot-press curing parameters corresponding to the second functional segment are lower than the hot-press curing parameters corresponding to the first functional segment. Step 7: After hot pressing, cool and shape the product and remove the clamps to obtain the finished anti-binding underwear with zoned elasticity differences at the waist and leg openings.

2. The manufacturing process of the anti-binding underwear according to claim 1, characterized in that, After step S1, the underwear blank is subjected to low-tension pre-shrinking treatment. The pre-shrinking is steam pre-shrinking, the pre-shrinking temperature is 75-85℃, and the pre-shrinking time is 20-35 minutes.

3. The manufacturing process of the anti-binding underwear according to claim 1, characterized in that, The partitioned stretch-limiting elastic film strip is divided into at least three sections along the circumference: a front section, a side section, and a rear section, wherein the side section is the second functional section. Furthermore, the side segment must satisfy at least one of the following conditions compared to the front and rear segments: smaller width, thinner thickness, or higher micropore density, in order to reduce the equivalent elastic constraint of the side segment.

4. The manufacturing process of the anti-binding underwear according to claim 1, characterized in that, The partitioned stretch-limiting elastic film tape has stress-relieving microstructures near the skin-contact edge. The stress-relieving microstructures are micropore arrays and micro-cut arrays, wherein the micropore diameter is 0.3-0.8 mm, the pore spacing is 1.5-4 mm, and 1-3 rows are arranged along the circumference.

5. The manufacturing process of the anti-binding underwear according to claim 1, characterized in that, In step S4, the hot melt adhesive is PUR hot melt adhesive or polyurethane hot melt adhesive. In the second functional section, intermittent adhesive application or reduced adhesive application per unit area is used, while in the first functional section, continuous adhesive application or increased adhesive application per unit area is used. After adhesive application, the adhesive film is pre-cured and dried at a temperature of 50-70°C for 10-15 minutes.

6. The manufacturing process of the anti-binding underwear according to claim 1, characterized in that, In step S5, the pre-stretch rate is satisfied that the pre-stretch rate at the corresponding position of the second functional segment is 2% to 6%, and the pre-stretch rate at the corresponding position of the first functional segment is 6% to 12%.

7. The manufacturing process for anti-binding underwear according to claim 1, characterized in that, Step S6 employs a two-stage partitioned hot-pressing curve: The pre-bonding section temperature is 75–85℃, the pressure is 0.15–0.30 MPa, and the time is 8–20 seconds; The curing section temperature is 85–95℃, the pressure is 0.25–0.45MPa, and the time is 10–35s; Furthermore, the curing pressure and time of the second functional stage are reduced by 10% to 30% compared to the first functional stage; In step S7, during cooling and shaping, maintain a light pressure of 0.05–0.15 MPa for 60–180 seconds.

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