A type of foam lettering film that is less prone to collapse and has a more three-dimensional feel

Abstract

This invention provides a foamed lettering film that is less prone to collapse and has a more three-dimensional effect, comprising a PET film layer and a TPU hot melt adhesive layer. A polyurethane foam layer and a polyester fiber layer are sequentially stacked between the PET film layer and the TPU hot melt adhesive layer. The polyurethane foam layer is configured with an oil-based structure to ensure stable and flat foaming. The polyester fiber layer is sandwiched between the TPU hot melt adhesive layer and the polyurethane foam layer to expand and solidify along with the polyurethane foam layer. Thus, by using an oil-based system for the polyurethane foam layer, the structural stability is improved, resulting in a smoother foam surface and a better three-dimensional effect. During the foaming process, the bubbles are evenly distributed and the air is smoothly vented, resulting in a high degree of surface flatness. Furthermore, the polyester fiber layer, tightly adhering to the inner side of the polyurethane foam layer, provides balanced elastic support during foaming expansion and expands and solidifies along with the foam after expansion, preventing local collapse of the cells during cooling or secondary processing.

Description

Technical Field

[0001] This utility model relates to the field of lettering film technology, specifically to a foamed lettering film that is not easily collapsed and has a more three-dimensional effect. Background Technology

[0002] Currently available foam lettering films are mainly composed of multiple layers of materials to achieve a three-dimensional effect for text or patterns on clothing, logos, or decorations. Common foam lettering films typically include: an outermost polyester protective film, a middle foam layer, and an innermost hot melt adhesive layer.

[0003] However, traditional foam layers are often made of a single polyurethane or EVA material. During the heating and foaming process, the cells are prone to partial collapse due to uneven heating or poor venting, resulting in unstable expansion height. Furthermore, the product is prone to shrinkage during long-term use or secondary processing, making it difficult to maintain a durable three-dimensional effect. At the same time, to ensure cell stability, some manufacturers reduce the amount of foaming agent or lower the foaming temperature. However, this leads to a decrease in foaming rate and uneven surface texture, affecting the adhesion and aesthetics of the lettering film to the substrate.

[0004] In particular, existing foam lettering films, relying solely on the three-dimensional support rigidity formed by the foam layer itself, have limited stability. Especially under wrinkling, stretching, or high-temperature environments, the lettering film is prone to deformation, leading to distortion of text or patterns and an inability to maintain a clear and three-dimensional visual effect over the long term. In addition, the film is prone to collapse during the cooling process after hot pressing, and after washing, the original three-dimensional effect becomes flat and loses its three-dimensionality, which can easily result in a poor user experience. Utility Model Content

[0005] In view of this, the purpose of this utility model is to provide a foamed lettering film that is not easy to collapse and has a more three-dimensional feel, so as to solve the above problems.

[0006] The present invention adopts the following solution:

[0007] This application provides a foamed lettering film that is less prone to collapse and has a more three-dimensional feel, comprising an outermost PET film layer and an innermost TPU hot melt adhesive layer. The PET film layer has viscosity and peel strength. The TPU hot melt adhesive layer is configured as a self-adhesive substrate. A polyurethane foam layer and a polyester fiber layer are sequentially stacked between the PET film layer and the TPU hot melt adhesive layer. The polyurethane foam layer is configured with an oil-based structure to facilitate stable and flat foaming. The polyester fiber layer is sandwiched between the TPU hot melt adhesive layer and the polyurethane foam layer to expand and solidify along with the polyurethane foam layer.

[0008] As a further improvement, the polyurethane foam layer is formed by uniformly mixing polyurethane emulsion and foaming powder.

[0009] As a further improvement, the foaming temperature range of the foaming powder is 150°C to 160°C.

[0010] As a further improvement, the oily system is a dispersion system with oil or organic solvent as the continuous phase, used to provide a colloid to a polyurethane foam layer.

[0011] As a further improvement, the viscosity of the PET film layer is in the range of 1.5 N / cm to 1.9 N / cm to ensure stable adhesion to the polyurethane foam layer.

[0012] As a further improvement, the peel force of the PET film layer is in the range of 400G to 450G to accommodate the foaming expansion of the polyurethane foam layer.

[0013] As a further improvement, the thickness of the polyester fiber layer is 150 μm to 300 μm, and the thickness of the polyurethane foam layer is more than 1.5 times the thickness of the polyester fiber layer.

[0014] As a further improvement, the PET film layer and the TPU hot melt adhesive layer are set to the same thickness, and the thickness of the PET film layer is less than 0.5 times the thickness of the polyester fiber layer.

[0015] By adopting the above technical solution, the present invention can achieve the following technical effects:

[0016] The foam lettering film of this application, which is less prone to collapse and has a more three-dimensional effect, adopts an oil-based system in the polyurethane foam layer, which makes the structure more stable, resulting in a smoother foam surface and a better three-dimensional effect. During the foaming process, the bubbles are evenly distributed and the air is smoothly vented, resulting in a high degree of surface flatness of the product. Furthermore, the polyester fiber layer is closely attached to the inner side of the polyurethane foam layer, which can provide balanced elastic support during foam expansion. After foam expansion, it can expand and shape with water, preventing the cells from collapsing locally during cooling or secondary processing.

[0017] 2. The design consists of layers of PET film, foam layer, fiber layer, and TPU adhesive layer, which work together to create a higher and clearer engraving pattern with a more three-dimensional look and feel. The oil-based foam layer has a certain degree of resilience, making it softer and more elastic to the touch. The outermost PET film has both the necessary mechanical strength and controllable peel force, allowing it to be smoothly peeled off after hot stamping without damaging the underlying foam structure. Combined with the high adhesion of the innermost TPU hot melt adhesive layer, it can firmly bond to various substrates such as fabric and leather without the need for additional glue or treatment. The layers are tightly bonded, and the overall interlayer shear strength is high, making it difficult for the layers to delaminate or peel. Attached Figure Description

[0018] Figure 1 This is a cross-sectional schematic diagram of a foamed lettering film that is not easily collapsed and has a more three-dimensional effect according to an embodiment of the present invention;

[0019] Figure 2 yes Figure 1 The diagram shows the enlarged TPU hot melt adhesive layer.

[0020] Icons: 1-PET film layer; 2-TPU hot melt adhesive layer; 3-polyurethane foam layer; 4-polyester fiber layer. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model. Therefore, the following detailed description of the embodiments of this utility model provided in the accompanying drawings is not intended to limit the scope of the claimed utility model, but merely to represent selected embodiments of this utility model.

[0022] Example

[0023] Combination Figures 1 to 2 This embodiment provides a foamed lettering film that is less prone to collapse and has a more three-dimensional feel, including an outermost PET film layer 1 and an innermost TPU hot melt adhesive layer 2. The PET film layer 1 has viscosity and peel strength. The TPU hot melt adhesive layer 2 is configured as a self-adhesive substrate. A polyurethane foam layer 3 and a polyester fiber layer 4 are sequentially stacked between the PET film layer 1 and the TPU hot melt adhesive layer 2. The polyurethane foam layer 3 is configured with an oil-based structure to facilitate stable and flat foaming. The polyester fiber layer 4 is sandwiched between the TPU hot melt adhesive layer 2 and the polyurethane foam layer 3 to expand and solidify along with the polyurethane foam layer 3.

[0024] The aforementioned foamed lettering film utilizes an oil-based system in its polyurethane foam layer 3, resulting in better structural stability, a smoother foamed surface, and a better three-dimensional effect. During the foaming process, the bubbles are evenly distributed and the air is smoothly vented, leading to a high degree of surface flatness. Furthermore, the polyester fiber layer 4 is tightly attached to the inner side of the polyurethane foam layer 3, providing balanced elastic support during foam expansion. After foam expansion, it can expand and solidify with the water, preventing local collapse of the cells during cooling or secondary processing.

[0025] In particular, the PET film, foam layer, fiber layer, and TPU adhesive layer are stacked in sequence. The combined effect of these multi-layered structures makes the engraved pattern higher and the outline clearer, giving it a three-dimensional look and feel. The oily foam layer itself has a certain degree of resilience, making it softer and more elastic to the touch. The outermost PET film has both the necessary mechanical strength and controllable peel force, allowing it to be smoothly peeled off after hot stamping without damaging the underlying foam structure. Combined with the high adhesion of the innermost TPU hot melt adhesive, it can firmly bond with various substrates such as fabric and leather without the need for additional glue or treatment. The layers are tightly bonded, and the overall interlayer shear strength is high, making it less prone to delamination or peeling.

[0026] In this embodiment, the polyurethane foam layer 3 is formed by uniformly mixing polyurethane emulsion and foaming powder. Specifically, after the polyurethane emulsion and foaming powder are fully mixed, the bubbles are evenly distributed throughout the oily system, avoiding the phenomenon of excessively large or small local pores caused by uneven dispersion of raw materials in traditional one-time foaming, thereby obtaining a dense and stable foam structure.

[0027] Preferably, the foaming temperature range of the foaming powder is between 150°C and 160°C. Particularly within the temperature range of 150°C, the foaming powder can fully decompose to generate gas, allowing the polyurethane foam layer 3 to achieve the ideal expansion ratio, resulting in a uniform and dense cell structure. This ensures a three-dimensional appearance while avoiding large pores or collapse caused by excessive expansion. Furthermore, this temperature range falls precisely below the temperature resistance limits of the PET film and TPU hot melt adhesive, ensuring that the PET film layer 1 does not undergo thermal deformation or aging, and preventing excessive flow or cross-linking of the TPU adhesive layer, thereby ensuring the overall stability of the multilayer composite structure throughout the foaming and cooling process.

[0028] It should be noted that the oily system is a dispersion system with oil or organic solvent as the continuous phase, used to provide the colloid to the polyurethane foam layer 3. Thus, the oily continuous phase can effectively stabilize the colloidal particles, preventing sedimentation or aggregation caused by phase separation during preparation and storage, thereby ensuring uniform mixing of the foaming powder and polyurethane emulsion, resulting in a finer and more consistent cell structure after foaming. Simultaneously, the oil or organic solvent as the continuous phase can reduce the surface tension of the system, enhance the interfacial wettability between the colloid and the polyurethane matrix, making it easier for the colloid to encapsulate and fix itself on the cell walls during foaming, improving the morphological stability and mechanical support effect of the cells.

[0029] Preferably, the viscosity of the PET film layer 1 is between 1.5 N / cm and 1.9 N / cm to ensure stable adhesion to the polyurethane foam layer 3. Furthermore, the peel force of the PET film layer 1 is between 400 G and 450 G to accommodate the foaming expansion of the polyurethane foam layer 3. In a preferred embodiment, the viscosity of the PET film layer 1 is 1.5 N / cm, and the peel force is 400 G. This not only ensures sufficient adhesion of the PET film layer to the polyurethane foam layer 3, preventing premature delamination during hot pressing, washing, or friction, but also allows for easy peeling without film breakage or residue of the underlying adhesive layer.

[0030] In this embodiment, the thickness of the polyester fiber layer 4 is 150µm to 300µm, and the thickness of the polyurethane foam layer 3 is more than 1.5 times the thickness of the polyester fiber layer 4. With this appropriate thickness, the polyester fiber layer 4 can provide precise support by closely adhering to the foam layer without causing the overall sheet to be too thick and affecting flexibility. The foam layer thickness is at least 1.5 times that of the fiber layer, ensuring sufficient height and elastic support during three-dimensional expansion, significantly improving the three-dimensional appearance and resilience.

[0031] In this embodiment, the PET film layer 1 and the TPU hot melt adhesive layer 2 are of equal thickness, and their thickness is less than 0.5 times the thickness of the polyester fiber layer 4. On one hand, the equal thickness of the outer PET film and the inner TPU adhesive layer allows for symmetrical thermal expansion and contraction during hot pressing and cooling, reducing stress concentration within the multi-layer composite structure and preventing edge warping or bubbling. On the other hand, the two relatively thin film layers facilitate rapid and uniform heat transfer to the intermediate foaming and fiber layers, achieving more stable foaming expansion and shaping, and improving production efficiency and consistency.

[0032] It is worth mentioning that the film structure constructed from the PET film layer 1, polyurethane foam layer 3, polyester fiber layer 4, and TPU hot melt adhesive layer 2 can maintain its three-dimensional effect without collapsing after a 5A standard water washing test. This foamed lettering film can be applied to clothing, bags, shoe materials, home textiles, advertising signage, and other fields, satisfying personalized pattern requirements while ensuring product durability and decorative effect.

[0033] The above are merely preferred embodiments of this utility model. The protection scope of this utility model is not limited to the above embodiments. All technical solutions that fall within the scope of this utility model's concept are protected by this utility model.

Claims

1. A foamed lettering film that is less prone to collapse and has a more three-dimensional feel, characterized in that, include: The outermost PET film layer has viscosity and peel strength; The innermost TPU hot melt adhesive layer is configured as a self-adhesive substrate. Among them, a polyurethane foam layer and a polyester fiber layer are sequentially stacked between the PET film layer and the TPU hot melt adhesive layer; Furthermore, the polyurethane foam layer is configured with an oil-based structural design to ensure stable and smooth foaming. Furthermore, the polyester fiber layer is sandwiched between the TPU hot melt adhesive layer and the polyurethane foam layer to expand and solidify along with the polyurethane foam layer.

2. The foamed lettering film that is not easily collapsed and has a more three-dimensional feel according to claim 1, characterized in that, The polyurethane foam layer is formed by uniformly mixing polyurethane emulsion and foaming powder.

3. The foamed lettering film that is not easily collapsed and has a more three-dimensional feel according to claim 2, characterized in that, The foaming temperature range of the foaming powder is 150°C to 160°C.

4. The foamed lettering film that is not easily collapsed and has a more three-dimensional feel according to claim 2, characterized in that, The oily system is a dispersion system with oil or organic solvent as the continuous phase, used to provide colloids to polyurethane foam layers.

5. The foamed lettering film that is not easily collapsed and has a more three-dimensional feel according to claim 1, characterized in that, The viscosity of the PET film layer is between 1.5 N / cm and 1.9 N / cm to ensure stable adhesion to the polyurethane foam layer.

6. The foamed lettering film that is not easily collapsed and has a more three-dimensional feel according to claim 1, characterized in that, The peel force of the PET film layer is between 400G and 450G to accommodate the foaming expansion of the polyurethane foam layer.

7. The foamed lettering film that is not easily collapsed and has a more three-dimensional feel according to claim 1, characterized in that, The thickness of the polyester fiber layer is 150um to 300um, and the thickness of the polyurethane foam layer is more than 1.5 times the thickness of the polyester fiber layer.

8. The foamed lettering film that is not easily collapsed and has a more three-dimensional effect according to claim 7, characterized in that, The PET film layer and the TPU hot melt adhesive layer are of equal thickness, and the thickness of the PET film layer is less than 0.5 times the thickness of the polyester fiber layer.

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