Process for reducing deformation of heat-shrinkable label

Abstract

The invention discloses a process for reducing deformation of a thermal shrinkage label. The process adapts to the core characteristics of automatic product entering, pressure-free natural shrinkage and no complex control device of traditional hot steam shrinkage equipment. According to the process, by changing the sequence of elements entering a hot steam shrinkage furnace, the elements enter the shrinkage furnace later, and in combination with a four-step collaborative process system of physical pre-positioning, steam gradient control, steam flow guide control and label element area entering the hot steam shrinkage furnace later, steam natural heat transfer and shrinkage stress distribution are optimized; and the stress concentration is obviously reduced. The element with the diameter of 12 mm-28 mm and the label with the specific shrinkage rate and thickness are applied under specific production parameters, the label deformation degree is effectively reduced, the product packaging quality is improved, unqualified products are reduced, complex devices such as visual positioning, resistance sensing and PLC control do not need to be relied on, adjustment can be achieved only through pure mechanical structure adjustment, and the production efficiency is improved. The device is low in transformation cost, easy to operate and capable of being widely applied to the field of product packaging of various small and medium-sized production enterprises.

Description

Technical Field

[0001] This invention relates to the field of packaging technology, and in particular to a process for reducing the deformation of heat-shrink labels. Background Technology

[0002] In the packaging industry, hot steam shrink wrapping equipment is widely used in heat shrink label packaging due to its advantages such as high heat transfer efficiency and ease of operation. Its working mode involves the product automatically entering the steam shrink oven via a conveyor belt. The label shrinks by relying on the heat generated by the natural diffusion of steam, without additional external pressure or complex control devices. However, in conventional processes, due to uneven steam distribution and differences in heating rates across different parts of the label, the label is prone to deformation, resulting in blurred or distorted key information or patterns, severely impacting product display and brand image.

[0003] Taking the current production process as an example:

[0004] - Shrink oven is 3 meters long

[0005] - Conveyor belt speed 320 bottles / min

[0006] - Each bottle spends 5.6 seconds in the shrink oven.

[0007] -Steam inlet pressure of the shrink furnace: 0.49 MPa

[0008] - Furnace temperature 76℃

[0009] - Furnace steam pressure: 0.39 MPa (natural steam environment pressure, no additional pressure applied)

[0010] - Control method: No visual positioning system, no resistance sensor, no PLC control system; basic equipment parameters are preset manually.

[0011] Under the above parameters, the deformation problem of heat shrink labels is particularly prominent. For example, excessive label deformation reduces the aesthetics of product packaging and the accuracy of information transmission. At the same time, the reduced presentation of label elements can easily lead to a large number of unqualified products, which greatly limits the improvement of product packaging quality and increases production costs. Summary of the Invention

[0012] This invention aims to solve the following technical problems existing in traditional label heat shrinking processes:

[0013] (1) Excessive deformation of labels leads to an increase in product defect rate;

[0014] (2) Excessive deformation of labels affects the aesthetics of product packaging and the accuracy of information transmission.

[0015] (3) The general label heat shrink process has changed and is difficult to adapt to traditional hot steam shrink equipment.

[0016] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: a process for reducing the deformation of heat-shrink labels, comprising:

[0017] A positioning structure is used to pre-position the label elements to ensure that the elements remain centered during transport;

[0018] A partition device is installed inside the hot steam shrink furnace to form multiple independent steam temperature control zones;

[0019] A flow guiding device is installed inside the hot steam shrink furnace to guide the steam to diffuse naturally and avoid localized steam accumulation.

[0020] The non-critical parts of the label are controlled to enter the hot steam shrink oven first, followed by the elemental region.

[0021] In this application, a four-step collaborative process is used to ensure that the shrinkage process of the element is controllable and the shrinkage effect is consistent. This process includes physical pre-positioning of the element, gradient control of steam, airflow guidance control of steam, and ensuring that the labeled element area enters the hot steam shrinkage furnace.

[0022] In some embodiments, the positioning structure is a mechanically guided positioning structure, particularly an adjustable guide wheel.

[0023] In some embodiments, the adjustable guide wheels are disposed on both sides of the conveyor belt, and the spacing between the guide wheels can be adjusted manually.

[0024] By adopting the above scheme, a mechanical guiding positioning structure is used in the physical positioning stage of the element. Adjustable guide wheel sets are installed on both sides of the conveyor belt. According to the diameter specifications of the element to be shrunk, the spacing of the guide wheels is manually adjusted to keep the element aligned in the center during the conveying process, so as to avoid the uneven shrinkage force caused by the offset.

[0025] In some embodiments, the adjustable guide wheel is made of high-temperature resistant rubber.

[0026] In some embodiments, the spacing between the guide wheels is set to "element diameter + 1.0~1.5mm".

[0027] By adopting the above solution, positioning can be achieved without additional clamping force, simply through physical limiting, and it is suitable for cylindrical elements with diameters of 12~28mm.

[0028] In some embodiments, the separating device is a physical separating plate, and the material of the separating plate is one or more of refractory metals, ceramics, and polymer materials.

[0029] In some embodiments, the plurality of independent steam temperature control zones include a first temperature control zone, a second temperature control zone, and a third temperature control zone.

[0030] Preferably, the temperatures of the first temperature control zone, the second temperature control zone, and the third temperature control zone are preset.

[0031] In some embodiments, the first temperature control area is near the furnace opening and is used for label pre-softening; the second temperature control area is in the middle section of the furnace body and is used for the natural shrinkage of the label; and the third temperature control area is near the furnace outlet and is used for the natural cooling of the label.

[0032] By adopting the above technical solution, a natural temperature gradient can be formed by utilizing the natural flow characteristics of steam and the heat insulation effect of the partition plate.

[0033] In some embodiments, the temperature of the first temperature control zone is 80~90°C.

[0034] By adopting the above technical solution, local wrinkling of elements caused by sudden heating can be avoided.

[0035] In some embodiments, the temperature of the second temperature control zone is 120~140°C.

[0036] In some embodiments, the flow rate is 0.5~0.8 m³ / h.

[0037] By adopting the above technical solution, stable heat can be provided for the natural contraction of elements.

[0038] In some embodiments, the temperature of the third temperature control zone is 60~70°C.

[0039] By adopting the above technical solution, the morphological stability of the element after shrinkage can be ensured.

[0040] In some embodiments, the flow guiding device is a flow guiding plate, the thickness of which is 2 mm and the material is one or more of refractory metals, ceramics, and polymer materials.

[0041] In some embodiments, the deflector has at least one of the following features:

[0042] a. The guide vanes are symmetrically arranged;

[0043] b. The angle between the guide plate and the axis of the hot steam shrink furnace is 10~30°;

[0044] c. The thickness of the guide plate is adapted to the hot steam shrink oven to ensure that the steam acts evenly on the label surface and the shrinkage stress is evenly distributed. The thickness of the guide plate is preferably 5~15cm.

[0045] d. When the preset thickness of the guide plate makes the temperature difference on the label surface ≤5℃, it is considered to be compatible with the hot steam shrink oven.

[0046] By adopting the above technical solution, the mechanical structure can guide the natural diffusion of steam and avoid local steam accumulation.

[0047] In some embodiments, controlling the label to enter the hot steam shrink oven includes at least one of the following features:

[0048] a. Optimize the mechanical structure of the bottle separator at the front end of the conveyor belt;

[0049] b. Adjust the spacing and rotation speed of the bottle-separating teeth;

[0050] c. Change the phase of the product arrangement on the conveyor belt;

[0051] d. The dwell time of each product in each of the temperature-controlled zones is precisely matched with the temperature of the temperature-controlled zones, wherein the product stays in the first temperature-controlled zone for 1.5 to 2.0 seconds, the product stays in the second temperature-controlled zone for 2.0 to 2.5 seconds, and the product stays in the third temperature-controlled zone for 1.0 to 1.5 seconds.

[0052] By adopting the above technical solution, the order in which elements enter the shrink furnace can be precisely controlled, and the residence time of each bottle of the product in each temperature zone can be precisely matched with the temperature gradient, ensuring a smooth natural shrinkage process.

[0053] The beneficial effects of this invention are that it can adapt to the simple operation characteristics of traditional hot steam shrink equipment, effectively reduce label deformation through purely mechanical structural adjustments and process optimization, ensure the clarity and integrity of key elements, improve the aesthetics of product packaging and the accuracy of information transmission, and enhance product market competitiveness; it significantly reduces the number of defective products caused by label deformation, lowers the scrap rate, and saves raw material costs; it eliminates the need to purchase additional complex devices such as visual positioning, resistance sensing, and PLC control, resulting in low modification costs; at the same time, it optimizes steam usage parameters, reduces steam waste, and lowers energy consumption; it is fully compatible with existing traditional hot steam shrink equipment, requiring no large-scale modification of the equipment, and can be achieved simply by adjusting the guide wheel spacing, installing separators and guide plates, and optimizing the bottle separator structure. The process steps are simple, and workers can operate it after simple training, making it easy to quickly promote and apply on the existing production lines of various small and medium-sized manufacturing enterprises. Attached Figure Description

[0054] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings required in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can obtain these drawings without any additional creative effort.

[0055] Figure 1 This invention provides a process for reducing the deformation of heat-shrinkable labels.

[0056] Figure 2 This is a comparison image of label sizes after heat shrinking using traditional methods and one embodiment of the present invention's method for reducing heat shrink label deformation.

[0057] Figure 3 This is a comparison chart of label parameters after batch statistics of traditional processes and one embodiment using the heat shrink label deformation reduction process of the present invention. Detailed Implementation

[0058] The technical solutions will now be clearly and completely described with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the examples described are only a part of the embodiments of the present invention and do not cover all possible implementations. Based on the embodiments of the present invention, all other embodiments that can be obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0059] The term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. In the description of the present invention, the terms "upper," "lower," "top," "bottom," etc., refer to the orientation or positional relationship based on the orientation or position shown in the accompanying drawings, and are used only for the convenience of describing the present invention and simplifying expression, and do not imply that the device or element must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0060] To illustrate the technical solutions provided in this application, the following detailed description is provided in conjunction with specific drawings and embodiments, taking "processing of labels in a hot steam shrink oven" as an example.

[0061] Please see Figure 1 , Figure 1 The process for reducing heat shrink label deformation in some embodiments of this application involves a four-step coordinated process: physical pre-positioning, steam gradient control, steam airflow guidance control, and ensuring that the label element area enters the hot steam shrink furnace. This ensures that the shrinkage process of the elements is controllable and the shrinkage effect is consistent.

[0062] The hot steam shrink oven is 3 meters long and has a permissible conveying speed of 320 bottles / minute.

[0063] In the physical pre-positioning process, high-temperature resistant rubber guide wheel sets are installed on both sides of the conveyor belt. The spacing between the guide wheels is adjusted manually by adjusting bolts according to the diameter of the produced element, ensuring that the spacing is "element diameter + 1.0~1.5mm", thereby achieving physical positioning during the element conveying process.

[0064] In the gradient control process of steam, three high-temperature resistant ceramic partition plates are installed in the shrink furnace to divide the furnace body into a preheating zone, a main shrinking zone, and a shaping zone, with a spacing of 1 meter between the partition plates. Symmetrical stainless steel guide plates are installed in each zone, with the angle between the guide plates and the furnace body axis fixed at 20° and the spacing set at 10 cm to guide the steam to diffuse evenly.

[0065] Meanwhile, by using the manual knob on the equipment, the steam inlet flow rate can be set to 0.5~0.8m³ / h, and the temperature of the main shrink zone can be finely adjusted according to the label material to ensure that the temperature of each area in the furnace is maintained within the preset range (preheating zone 80~90℃, main shrink zone 120~140℃, shaping zone 60~70℃), without the need for real-time monitoring and adjustment.

[0066] The steam inlet pressure is 0.49 MPa, and the steam pressure inside the steam furnace is 0.39 MPa. At this time, the steam furnace is in a natural steam environment without any additional pressure applied.

[0067] Each product spends 5.4 to 6 seconds in the hot steam shrink oven, with the product spending 1.5 to 2.0 seconds in the preheating zone, 2.0 to 2.5 seconds in the main shrink zone, and 1.0 to 1.5 seconds in the setting zone.

[0068] In the steam airflow guidance control process, mechanical guide plates (made of stainless steel, 2mm thick) with a fixed angle are installed inside the shrink furnace. The guide plates are symmetrically arranged, with a fixed angle of 20° to the furnace axis. The mechanical structure guides the steam to diffuse naturally, avoiding local steam accumulation. The spacing between the guide plates is preset to 10cm according to the equipment specifications, which is compatible with the size of mainstream hot steam shrink furnaces. At this time, the steam acts evenly on the label surface, with a surface temperature difference of ≤5℃, and the shrinkage stress is evenly distributed.

[0069] In the process of the label element area entering the hot steam shrink oven, the tooth spacing of the bottle separator at the front end of the conveyor belt is adjusted (set to "element diameter + 2.0mm" according to the element diameter) and the rotation speed (matched with the conveyor belt speed to ensure uniform product arrangement) so that the non-critical parts of the label enter the shrink oven first, and the element area enters later, achieving precise control of the entry sequence.

[0070] Please see the appendix Figure 2The standard measurement position of the label is as follows: the original size of the conventional label is 17.7mm (suitable for elements with a diameter range of 12~28mm), and the label thickness is 0.043-0.050mm. After processing by the embodiment of this invention, the dimensional parameters of the conventional label before and after heat shrinkage are statistically analyzed. When the size of the heat-shrinked label is greater than 16.5mm and the shrinkage size is greater than the original size × 0.93, the heat-shrinked label is considered qualified. The size of the label after the heat shrinkage reduction label process proposed in this invention is 17.48mm > 16.5mm (corresponding to the original size of 17.7mm). Furthermore, for elements with a diameter of 12~28mm, the shrinkage must meet the requirement of "shrinkage size > original size × 0.93", the lateral shrinkage rate of the label is ≥70%, and the longitudinal shrinkage rate of the label is 3~5%. Therefore, the label after the heat shrinkage reduction label process proposed in this invention is qualified.

[0071] In contrast, the label is heat-shrinked using the traditional method in an advanced shrink oven, resulting in a shrinkage size of 16.35mm, which does not meet the requirement of being greater than 16.5mm. Meanwhile, the label treated with the deformation-reducing process of this invention exhibits significantly less deformation than labels heat-shrinked using the traditional method, thus reducing the defect rate of finished products.

[0072] Please see the appendix Figure 3 The table below illustrates the effectiveness of the heat shrink label reduction process described in this invention in actual production. Data from multiple batches of labels produced were statistically analyzed. The statistical data after multiple batches of heat shrinking labels using both the heat shrink label reduction process described in this invention and traditional processes showed that "image in front" corresponds to the traditional process using an advanced shrink oven, while "image in back" corresponds to the heat shrink label reduction process described in this invention. The pass rate for multiple batches with "image in back" labels was significantly higher than that of batches with "image in front." In continuous production testing of multiple batches with "image in back," the pass rate was generally higher (mostly >88%), indicating that the process described in this invention performs stably in production, effectively and consistently improving the pass rate, reducing heat shrink deformation, lowering production costs, and enhancing product quality.

[0073]

[0074] After numerous production experiments, the statistical data shown in the table below was obtained. Using the traditional method of heat shrinking labels by first placing the label elements into the shrink furnace, the maximum deformation of the labels was 28.87%, the average deformation was 15.25%, and the failure rate was 94%. In contrast, the labels produced using the heat shrink reduction label process of this invention had a maximum deformation of 23.8%, an average deformation of 6.78%, and a failure rate of 8.13%. Therefore, labels produced using the heat shrink reduction label deformation process of this invention are significantly superior to those produced using the traditional method of first placing the label elements into the shrink furnace in terms of deformation and failure rate. This significantly reduces the degree of heat shrinkage, resulting in labels with higher clarity and more accurate information display after heat shrinking. Furthermore, it effectively improves the product qualification rate with minimal modifications to the steam shrink furnace, greatly reducing production costs.

[0075]

[0076] The above description represents preferred embodiments and implementation methods of the present invention. It should be noted that those skilled in the art can make various improvements and adjustments without departing from the principles of the present invention, and these improvements and adjustments should also be considered within the scope of protection of the present invention.

Claims

1. A process for reducing deformation of heat-shrink labels, characterized in that, include: A positioning structure is used to pre-position the label elements to ensure that the elements remain centered during transport; A partition device is installed inside the hot steam shrink furnace to form multiple independent steam temperature control zones; A flow guiding device is installed inside the hot steam shrink furnace to guide the steam to diffuse naturally and avoid localized steam accumulation. The non-critical parts of the label are controlled to enter the hot steam shrink oven first, followed by the elemental parts.

2. The process for reducing deformation of heat-shrink labels according to claim 1, characterized in that, The positioning structure is a mechanically guided positioning structure, particularly an adjustable guide wheel.

3. The process for reducing deformation of heat-shrinkable labels according to claim 2, characterized in that, The adjustable guide wheels are located on both sides of the conveyor belt.

4. The process for reducing deformation of heat-shrinkable labels according to claim 2, characterized in that, The adjustable guide wheel is made of high-temperature resistant material.

5. The process for reducing deformation of heat-shrinkable labels according to claim 3, characterized in that, The spacing between the guide wheels is set to "element diameter + 1.0~1.5mm".

6. The process for reducing deformation of heat-shrink labels according to claim 1, characterized in that, The separating device is a physical separating plate, and the material of the separating plate is one or more of refractory metals, ceramics, and polymer materials.

7. The process for reducing deformation of heat-shrink labels according to claim 1, characterized in that, The multiple independent steam temperature control zones include a first temperature control zone, a second temperature control zone, and a third temperature control zone.

8. The process for reducing deformation of heat-shrinkable labels according to claim 7, characterized in that, The temperatures of the first temperature control zone, the second temperature control zone, and the third temperature control zone are preset.

9. The process for reducing deformation of heat-shrinkable labels according to claim 7, characterized in that, The first temperature control area is located near the furnace opening and is used for label pre-softening.

10. The process for reducing deformation of heat-shrinkable labels according to claim 7, characterized in that, The temperature of the first temperature control zone is 80~90℃.

11. The process for reducing deformation of heat-shrinkable labels according to claim 7, characterized in that, The second temperature control zone is located in the middle section of the furnace body and is used for the natural shrinkage of the labels.

12. The process for reducing deformation of heat-shrinkable labels according to claim 7, characterized in that, The temperature of the second temperature control zone is 120~140℃.

13. The process for reducing deformation of heat-shrinkable labels according to claim 12, characterized in that, The temperature control of the second temperature control zone is achieved by adjusting the total flow rate of the steam inlet, which is 0.5~0.8 m³ / h.

14. The process for reducing deformation of heat-shrinkable labels according to claim 7, characterized in that, The third temperature control zone is located near the furnace outlet and is used for the natural cooling of the labels.

15. The process for reducing deformation of heat-shrinkable labels according to claim 14, characterized in that, The temperature of the third temperature control zone is 60~70℃.

16. The process for reducing deformation of heat-shrinkable labels according to claim 1, characterized in that, The flow guiding device is a flow guiding plate, which has a thickness of 2mm and is made of one or more of refractory metals, ceramics, and polymer materials.

17. The process for reducing deformation of heat-shrinkable labels according to claim 16, characterized in that, The deflector plate has at least one of the following characteristics: a. The guide vanes are symmetrically arranged; b. The angle between the guide plate and the axis of the hot steam shrink furnace is 10°~30°; c. The thickness of the guide plate is adapted to the hot steam shrink oven to ensure that the steam acts evenly on the label surface and the shrinkage stress is evenly distributed. The thickness of the guide plate is preferably 5~15cm. d. When the preset thickness of the guide plate makes the temperature difference on the label surface ≤5℃, it is considered to be compatible with the hot steam shrink oven.

18. A process for reducing deformation of heat-shrinkable labels according to any one of claims 1 or 7-15, characterized in that, The operation of controlling the label to enter the hot steam shrink oven includes at least one of the following features: a. Optimize the mechanical structure of the bottle separator at the front end of the conveyor belt; b. Adjust the spacing and rotation speed of the bottle-separating teeth; c. Change the phase of the product arrangement on the conveyor belt; d. The dwell time of each product in each of the temperature control zones is precisely matched with the temperature of the temperature control zone, wherein the product stays in the first temperature control zone for 1.5 to 2.0 seconds, the product stays in the second temperature control zone for 2.0 to 2.5 seconds, and the product stays in the third temperature control zone for 1.0 to 1.5 seconds.

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