Plastic draw-bar box shell and preparation method thereof

Abstract

The invention discloses a plastic draw-bar box shell and a preparation method thereof. The shell is sequentially provided with an outer layer, a middle layer, a bonding layer and an inner cloth layer from outside to inside, the outer layer is a BOPP (Biaxially-oriented Polypropylene) film, the middle layer is formed by compounding a plurality of layers of PP flat filament woven fabrics, the bonding layer is a CPP (Chlorinated Polypropylene) film, and the inner cloth layer is PP textile cloth or PP gridding cloth. According to the invention, a multi-layer composite structure is adopted, and the prepared plastic draw-bar box shell realizes the balance of light weight and strength through the cooperation of each layer of material and structure, and has excellent low-temperature performance. According to the process, integral molding is achieved through mold pressing, the problems that an existing traditional box shell is prone to softening at high temperature and prone to embrittlement at low temperature are solved, splicing is not needed in the process, multi-layer compounding is completed through one procedure, the production efficiency is high, energy consumption is low, and the machining cost is low.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of luggage, and particularly relates to a plastic trolley case shell and a preparation method thereof. BACKGROUND

[0002] At present, plastic trolley cases occupy more than 70% of the global trolley case market due to advantages such as lightweight, easy processing and controllable cost, and the shell as a core bearing component is mainly prepared by two process routes of injection molding of PP or modified PP material or vacuum forming of PC material. However, due to the limitations of materials and production processes, neither injection molding nor vacuum forming can balance lightweight and toughness. When the shell is light and thin, the impact resistance and overall toughness will decrease significantly; on the contrary, increasing the strength of the shell will increase the weight of the product significantly.

[0003] Another obvious weakness of the existing plastic trolley case shell is poor low-temperature performance of the shell. When the PP or PC material trolley case is used in low-temperature climate conditions, for example, below-12℃, the shell becomes brittle and is prone to breakage. The low-temperature performance defect has seriously limited the application scenarios of the trolley case. SUMMARY

[0004] In order to overcome the deficiencies of the prior art, the purpose of the present application is to provide a plastic trolley case shell with high strength, light weight and excellent low-temperature performance and a preparation method thereof.

[0005] The present application is realized by the following technical solutions: A plastic trolley case shell, which is sequentially provided with an outer layer, an intermediate layer, a bonding layer and an inner cloth layer from outside to inside; the outer layer is a BOPP film, the intermediate layer is a composite of a plurality of layers of PP flat filament woven cloth, the bonding layer is a CPP film, and the inner cloth layer is a PP woven cloth or a PP mesh cloth.

[0006] The present application adopts a biaxially oriented polypropylene film (BOPP) as an outer protective film, and the BOPP film can improve the appearance and scratch resistance of the case, and enhance the impact resistance.

[0007] When the outer BOPP film and the intermediate layer of the plurality of layers of PP flat filament woven cloth are molded, the surface resin on the flat filament becomes a molten state under the action of temperature, and at the same time, due to the action of pressure, the molten resin will fill between the cloth and the cloth and between the cloth and the film to form a firm chemical bond to constitute a high-strength case shell. The surface BOPP film further enhances its waterproofness, pollution resistance and scratch resistance.

[0008] According to some preferred embodiments of the present application, the thickness of the outer layer is 0.01-0.08 mm. The present application realizes better scratch resistance and water and pollution resistance by the synergistic effect of the BOPP film and the multi-layer PP flat filament woven cloth, and the thickness of the outer layer only needs to be 0.01-0.08 mm.

[0009] The present application first creatively uses a plate material laminated and compounded by a multi-layer PP flat filament woven cloth as the main framework of the shell. The PP flat filament woven cloth forms a high-strength network structure through the interlacing of the warp and weft directions, and the multi-layer compounding further disperses the stress and reduces the risk of single-point damage. The intermediate layer has obvious advantages in the balance between light weight and high strength.

[0010] According to some preferred embodiments of the present application, the unit area weight of the PP flat filament woven cloth is 80-150 g / m2.

[0011] According to some preferred embodiments of the present application, the number of layers of the multi-layer PP flat filament woven cloth is ≥3 layers, and preferably 5-15 layers.

[0012] The present application can adjust the number of layers of the woven fabric used by the plate according to the required thickness of the plate and the grammage of the woven fabric material. As a preferred embodiment, the number of layers used by the 20-inch box shell is 5-8 layers, the 24-inch is 6-10 layers, the 28-inch is 7-12 layers, and the 31-inch is 8-14 layers.

[0013] According to some preferred embodiments of the present application, the warp tensile load of the PP flat filament woven cloth is >360 N / 50 mm, and the weft tensile load is >340 N / 50 mm, which is determined according to GB / T 1040.3-2006.

[0014] The present application uses a cast polypropylene film (CPP) prepared from copolymerized PP instead of traditional EVA glue / hot melt glue as the bonding layer. The material of the intermediate layer and the inner cloth layer belongs to the PP system, and can form a chemical bond after melting, which can greatly increase the bonding strength of the intermediate layer and the inner cloth layer.

[0015] According to some preferred embodiments of the present application, the thickness of the bonding layer is 0.01-0.06 mm.

[0016] The bonding layer of the present application uses a CPP film prepared from copolymerized PP, and the melting point is 150-163℃, and the melt index is 6 g / 10 min-10 g / 10 min, which is determined according to GB / T 3682.1-2018.

[0017] The inner cloth layer of the present application uses a PP textile cloth or a PP mesh cloth, which mainly increases the internal texture and reduces the use of internal materials of the final box shell product. While further achieving the purpose of light weight, it avoids introducing non-PP materials to facilitate the recycling of the box shell.

[0018] The present invention also provides a method for preparing the above-mentioned plastic trolley case shell, comprising the following steps: (1) Stack the outer layer, intermediate layer, adhesive layer and inner fabric layer materials in sequence and place them in a preheating press for preheating. The preheating temperature is 130-150℃, the preheating pressure is 0.1-0.2 MPa, and the pressurization time is 3-5 minutes; (2) Place the preheated sheet into a hot press mold for hot pressing. The hot pressing temperature is 150-160℃, the pressure is 1.0-5.0 MPa, and the pressing time is 30s-120s. (3) After hot pressing, hold the pressure until the mold temperature drops below 60°C to allow the workpiece to cool and solidify. Then open the mold to obtain the plastic trolley case shell.

[0019] Compared with the prior art, the present invention has the following beneficial effects: This invention employs a multi-layer composite structure (outer BOPP layer + middle PP flat yarn woven fabric + bonding layer CPP + inner fabric layer PP textile / mesh fabric). Through the synergy of the materials and structures in each layer, the resulting plastic trolley case shell has a tensile strength greater than 150MPa, and the weight of the 24-inch case shell top or bottom cover is less than 500g, achieving a balance between lightweight and strength. Furthermore, it exhibits excellent low-temperature performance without cracking when dropped at -30℃.

[0020] The plastic trolley case shell of this invention is made of PP material, which can be 100% recycled as a whole without disassembly. It has low energy consumption during recycling, high recycling rate, and significantly reduces the total life cycle cost.

[0021] This invention integrates an outer layer, a middle layer, an adhesive layer, and an inner fabric layer through molding. This process eliminates the need for additional adhesives. During molding, the multiple layers of materials melt and bond together under high temperature and pressure, forming a strong chemical bond. This avoids the problems of traditional adhesive layers being prone to peeling and softening at high temperatures and brittleness at low temperatures. Furthermore, this process eliminates the need for splicing, completing the multi-layer composite in a single step, resulting in high production efficiency, low energy consumption, and low processing costs. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of a plastic trolley case shell. Detailed Implementation

[0023] The present invention will be further illustrated below through specific embodiments. The following embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the following embodiments.

[0024] Unless otherwise specified, all materials used in this invention can be purchased commercially or prepared using conventional methods.

[0025] The materials used in this invention are sourced from the following sources: PP flat yarn woven fabric: produced by Suzhou Lingji Textile Technology Co., Ltd., weight 130g / ㎡, maximum tensile load: warp 397 N / 50mm, weft 349 N / 50mm, tested according to GB / T 1040.3-2006. Example 1

[0026] like Figure 1 As shown, a plastic trolley case shell is provided with an outer layer 1, a middle layer 2, and an adhesive layer from the outside to the inside. The outer layer 1 is a BOPP film with a thickness of 0.05 mm, the middle layer 2 is composed of 6-10 layers of PP flat yarn woven fabric, the adhesive layer 3 is a CPP film prepared by copolymer PP through casting process with a thickness of 0.04 mm, and the inner fabric layer 4 is a PP textile fabric.

[0027] Its preparation process includes the following steps: (1) Stack the outer layer, middle layer, adhesive layer and inner fabric layer materials in sequence, place them in a hot press to preheat the press plate, the preheating temperature is 140℃, the preheating pressure is 0.15 MPa, and the pressurization time is 4 minutes; (2) Place the preheated sheet into a hot press mold for hot pressing. The hot pressing temperature is 155℃, the pressure is 3.0 MPa, and the pressing time is 80s. (3) After hot pressing, hold the pressure until the mold temperature drops below 60°C, then open the mold to obtain the plastic trolley case shell. Example 2

[0028] The structure of the plastic trolley case shell is the same as that in Example 1, except that the middle layer is composed of 5-8 layers of PP flat yarn woven fabric, and the inner fabric layer 4 is PP mesh fabric.

[0029] Its preparation process includes the following steps: (1) Stack the outer layer, middle layer, adhesive layer and inner fabric layer materials in sequence, place them in the hot press to preheat the press plate, the preheating temperature is 130℃, the preheating pressure is 0.2 MPa, and the pressurization time is 3 minutes; (2) Place the preheated sheet into a hot press mold for hot pressing. The hot pressing temperature is 150℃, the pressure is 2.0 MPa, and the pressing time is 100s. (3) After hot pressing, hold the pressure until the mold temperature drops below 60°C, then open the mold to obtain the plastic trolley case shell. Example 3

[0030] The structure of the plastic trolley case shell is the same as that in Example 1, except that the middle layer is composed of 7-12 layers of PP flat yarn woven fabric.

[0031] Its preparation process includes the following steps: (1) Stack the outer layer, middle layer, adhesive layer and inner fabric layer materials in sequence, place them in a hot press to preheat the press plate, the preheating temperature is 150℃, the preheating pressure is 0.1 MPa, and the pressurization time is 5 minutes; (2) Place the preheated sheet into a hot press mold for hot pressing. The hot pressing temperature is 160℃, the pressure is 4.0 MPa, and the pressing time is 60s. (3) After hot pressing, hold the pressure until the mold temperature drops below 60°C, then open the mold to obtain the plastic trolley case shell.

[0032] Comparative Example 1: PP Injection Molded Box Shell Modified PP in a molten state is directly injected into the mold cavity using an injection molding machine to form the final product.

[0033] Table 1 Performance test results of the examples and comparative examples

[0034] As shown in Table 1, under the condition that the specific gravity is basically the same, compared with the traditional PP injection molded box shell of Comparative Example 1, the tensile strength of the plastic trolley box shell prepared by the present invention is increased by more than 10 times and the weight is reduced by more than 30%, achieving a balance between lightweight and strength. Moreover, it does not crack when dropped at a low temperature of -30℃, and has excellent low temperature performance.

Claims

1. A plastic trolley case shell characterized in that, The shell is sequentially provided with an outer layer (1), an intermediate layer (2), a bonding layer (3) and an inner cloth layer (4) from outside to inside; the outer layer is a BOPP film, the intermediate layer is composed of a plurality of layers of PP flat filament woven cloth, the bonding layer is a CPP film, and the inner cloth layer is a PP textile cloth or a PP mesh cloth.

2. The plastic trolley case shell of claim 1, wherein, The thickness of the outer layer is 0.01-0.08mm.

3. The plastic trolley case shell of claim 1, wherein, The unit area weight of the PP flat filament woven cloth is 80g / m2-150g / m2.

4. The plastic trolley case shell of claim 1, wherein, The number of layers of the multi-layer PP flat filament woven cloth is ≥3 layers, preferably 5-15 layers.

5. The plastic trolley case shell of claim 1, wherein, The warp tensile load of the PP flat filament woven cloth is >360 N / 50mm, and the weft tensile load is >340 N / 50mm, determined according to GB / T 1040.3-2006.

6. The plastic trolley case shell of claim 1, wherein, The thickness of the bonding layer is 0.01-0.06mm.

7. The plastic trolley case shell of claim 1, wherein, The melting point of the CPP film is 150-163℃, and the melt index is 6g / 10min-10g / 10min, determined according to GB / T 3682.1-2018.

8. The method of manufacturing a plastic trolley case shell according to any one of claims 1 to 7, wherein, The method comprises the following steps: (1) The materials of the outer layer, the intermediate layer, the bonding layer and the inner cloth layer are sequentially stacked and combined, and are placed in a hot press for preheating, the preheating temperature is 130-150℃, the preheating pressure is 0.1-0.2 Mpa, and the pressurization time is 3-5 minutes; (2) The preheated plate is placed in a hot press mold for hot pressing, the hot pressing temperature is 150-160℃, the pressure is 1.0-5.0 MPa, and the pressurization time is 30-120s; (3) After hot pressing, the pressure is maintained until the mold temperature drops below 60℃, the mold is opened, and the plastic draw-bar box shell is obtained.

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