Anti-shrinkage agent for sole foaming material and preparation method thereof

Abstract

The invention discloses an anti-shrinkage agent used for a sole foam material and a preparation method thereof, characterized in that it is prepared from the raw materials including the following components: 10-50 parts of a polyolefin elastomer, 10-60 parts of a low-density polyethylene, and 10-30 parts of an ethylene-vinyl acetate copolymer. It can be added as a raw material to the molding process of the foam material to improve the crystallinity of the product, so that the crystallinity is improved and the heat resistance and heat shrinkage resistance of the material are improved. The obtained material has all the excellent physical properties of traditional materials, and overcomes the shortcomings of the foam shoe material such as not being resistant to high temperature, being easy to shrink, and being unstable in size, and is suitable for promotion and application in the field of foam material processing.

Description

Technical Field

[0001] The invention relates to the field of polymer materials, in particular to an anti-shrinkage agent used for processing sole foaming materials and a preparation method thereof. Background Art

[0002] With the improvement of people's living standards and the change of consumption concepts, the requirements for comfort, durability and aesthetics of footwear products are increasing. EVA and TPU foamed footwear materials are made through cross-linking, chemical foaming or physical foaming processes, which can effectively achieve lightweight materials while maintaining their good elasticity and comfort. Therefore, casual shoes, sandals, slippers and other footwear products produced by direct foaming of these two materials are deeply loved by consumers, especially among modern consumers who pursue quality of life and comfort, and have a broad market base.

[0003] However, despite the many advantages of EVA and TPU foamed shoe materials, their softness and low crystallinity also bring some technical challenges. These characteristics make the materials prone to shrinkage after foaming, especially in high temperature environments, resulting in dimensional instability. This problem not only affects the subsequent bonding process of the shoe material, such as the bonding of the sole to the upper, but may also have an adverse effect on the overall appearance and wearing experience of the shoe.

[0004] Specifically, when the shoe material is heated in a high temperature environment, the molecular chains inside it may rearrange due to thermal motion, resulting in a reduction in the volume of the material, which is called "shrinkage". This shrinkage phenomenon is particularly evident in EVA and TPU foam materials because they have higher flexibility and lower crystallinity, making the molecular chains more susceptible to thermal motion. When the shoe material shrinks, it may not only cause the adhesion between the sole and the upper to fail, but also reduce the overall size of the shoe, affecting the comfort and aesthetics of wearing.

[0005] Therefore, how to overcome the technical difficulties of EVA and TPU foam materials that are prone to shrinkage and dimensional instability at high temperatures has become an important research direction for improving the quality of footwear products and consumer satisfaction. Summary of the invention

[0006] The present invention is to solve the problem of quality decline of foaming materials due to material shrinkage, and provides an anti-shrinkage agent for sole foaming materials. The anti-shrinkage agent is added as a raw material in the molding process of the foaming material, thereby improving the crystallization performance of the foaming material. With the improvement of crystallinity, the heat resistance and heat shrinkage resistance of the foaming material are further improved. The sole foaming material after adding the anti-shrinkage agent has all the excellent physical properties of traditional materials, and at the same time overcomes the shortcomings of foaming shoe materials such as not being resistant to high temperature, easy to shrink, and unstable size, and is suitable for promotion and application in the field of foaming material processing.

[0007] The anti-shrinkage agent for the sole foaming material provided by the invention is prepared from raw materials comprising the following components: 10-50 parts of polyolefin elastomer, 10-60 parts of low-density polyethylene and 10-30 parts of ethylene-vinyl acetate copolymer.

[0008] As a further embodiment of the present invention: the polyolefin elastomer is selected from vinyl polyolefin elastomer and / or propylene polyolefin elastomer.

[0009] As a further solution of the present invention: the melt index of the low-density polyethylene is 1-5 g / 10 min;

[0010] As a further embodiment of the present invention: the vinyl acetate content of the ethylene-vinyl acetate copolymer is 18-26%;

[0011] As a further embodiment of the present invention: an anti-shrinkage agent for a sole foam material further comprises 1-10 parts of a processing aid and 1-10 parts of a compatibilizer;

[0012] As a further embodiment of the present invention: the processing aid is one or more of zinc stearate, stearic acid or mesoamide;

[0013] As a further solution of the present invention: the compatibilizer is a polyolefin elastomer graft;

[0014] The method for preparing an anti-shrinkage agent for use in a sole foaming material provided by the present invention comprises the following steps:

[0015] S1 Accurately weigh various materials, add various raw materials and processing aids into a high-speed mixer and stir for 2-10 minutes to mix evenly to obtain mixed raw materials;

[0016] S2 sends the mixed material into a twin-screw extruder for granulation;

[0017] S3 sets the front zone temperature to 90-220℃ and the head temperature to 150-200℃;

[0018] S4 sets the twin-screw speed to 30 Hz, the pelletizing speed to 20 Hz, the vacuum to 0.08 MPa, and extrude water-cooled pellets to obtain anti-shrinkage agent masterbatch for foaming materials.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. This product can improve the crystallization performance inside the foam material products, make the crystallinity of the material higher, thereby making its internal support capacity stronger and improving its resistance to heat shrinkage.

[0021] 2. The foamed material product prepared using the anti-shrinkage agent provided by the present invention has the advantages of low shrinkage and high temperature resistance, and will not affect other properties of the product.

[0022] 3. The anti-shrinkage agent of the present invention has a simple production process, excellent product uniformity, good compatibility with resin, and low cost.

[0023] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention, but it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should all be deemed to fall within the scope of protection of the present invention.

[0025] Example 1

[0026] An anti-shrinkage agent for foam material processing is prepared from the following components:

[0027] Polyolefin elastomer (Vistamaxx6102): 20 parts;

[0028] Low density polyethylene (DOW 2426): 60 parts;

[0029] Ethylene-vinyl acetate copolymer (Formosa Plastics 7470): 10 parts;

[0030] Intermediate acid amide: 2 parts;

[0031] Compatibilizer (polyolefin elastomer grafted with maleic anhydride): 8 parts.

[0032] The preparation method of the anti-shrinkage agent is as follows: various materials are accurately weighed according to the above formula, various raw materials and processing aids are added into a high-speed mixer and stirred for 2-10 minutes, after being evenly mixed, an extruder is used to directly extrude and granulate to obtain anti-shrinkage agent particles.

[0033] Example 2

[0034] An anti-shrinkage agent for foam material processing is prepared from the following components:

[0035] Polyolefin elastomer (SABIC 1055): 30 parts;

[0036] Low-density polyethylene (Sinopec TR144): 50 parts;

[0037] Ethylene-vinyl acetate copolymer (Formosa Plastics 7470): 10 parts;

[0038] Intermediate acid amide: 2 parts;

[0039] Compatibilizer (polyolefin elastomer grafted with maleic anhydride): 8 parts.

[0040] The preparation method of the anti-shrinkage agent is as follows: various materials are accurately weighed according to the above formula, various raw materials and processing aids are added into a high-speed mixer and stirred for 2-10 minutes, after being evenly mixed, an extruder is used to directly extrude and granulate to obtain anti-shrinkage agent particles.

[0041] Example 3

[0042] An anti-shrinkage agent for foam material processing is prepared from the following components:

[0043] Polyolefin elastomer (Vistamaxx6102): 30 parts;

[0044] Low density polyethylene (Sinopec TR144): 40 parts;

[0045] Ethylene-vinyl acetate copolymer (Formosa Plastics 7470): 20 parts;

[0046] Intermediate acid amide: 2 parts;

[0047] Compatibilizer (polyolefin elastomer grafted with maleic anhydride): 8 parts.

[0048] The preparation method of the anti-shrinkage agent is as follows: various materials are accurately weighed according to the above formula, various raw materials and processing aids are added into a high-speed mixer and stirred for 2-10 minutes, after being evenly mixed, an extruder is used to directly extrude and granulate to obtain anti-shrinkage agent particles.

[0049] Implementation Case 4

[0050] The anti-shrinkage agent masterbatch prepared in Examples 1, 2, and 3 was added as a raw material to a conventional foaming molding process to prepare a foaming material test piece, and the physical properties of the material were tested. Sample 1 was added with 5% of the anti-shrinkage agent prepared in Example 1; Sample 2 was added with 8% of the anti-shrinkage agent prepared in Example 1; Sample 3 was added with 10% of the anti-shrinkage agent prepared in Example 1; Sample 4 was added with 5% of the anti-shrinkage agent prepared in Example 2; Sample 5 was added with 8% of the anti-shrinkage agent prepared in Example 2; Sample 6 was added with 10% of the anti-shrinkage agent prepared in Example 2; Sample 7 was added with 5% of the anti-shrinkage agent prepared in Example 3; Sample 8 was added with 8% of the anti-shrinkage agent prepared in Example 3; Sample 9 was added with 10% of the anti-shrinkage agent prepared in Example 3.

[0051] Comparative Example 1: A foamed material was prepared by conventional process without adding an anti-shrinkage agent, and its physical properties were tested.

[0052] The test results are shown in Table 1.

[0053]

[0054] It can be seen that the thermal shrinkage of the material with the anti-shrinkage agent is significantly reduced, and becomes lower as the amount of anti-shrinkage agent added increases. Moreover, the addition of the anti-shrinkage agent does not affect other performance indicators of the material, and the surface of the material is smooth and crack-free.

[0055] Example 5

[0056] The anti-shrinkage agent for the sole foam material provided in this embodiment has the following raw material composition: polyolefin elastomer (vinyl polyolefin elastomer): 30 parts; low-density polyethylene (melt index is 3g / 10min): 40 parts; ethylene-vinyl acetate copolymer (vinyl acetate content is 21%): 20 parts; processing aid (zinc stearate): 5 parts; compatibilizer (polyolefin elastomer graft): 5 parts. The preparation method is as follows:

[0057] Accurately weigh the above materials, and add the polyolefin elastomer, low-density polyethylene, ethylene-vinyl acetate copolymer, processing aid and compatibilizer into a high-speed mixer.

[0058] The mixer speed was set to 500 revolutions per minute and the mixing time was set to 5 minutes to ensure that the various raw materials were mixed evenly to obtain a mixed raw material.

[0059] The obtained mixed raw material is fed into a twin-screw extruder for granulation.

[0060] The front zone temperature of the twin-screw extruder was set to 150°C and the head temperature was set to 180°C.

[0061] The twin-screw speed was set to 30 Hz, the pelletizing speed was set to 20 Hz, and the vacuum degree was set to 0.08 MPa. The anti-shrinkage agent masterbatch for the foaming material was obtained by an extrusion water-cooling pelletizing process.

[0062] The obtained material was subjected to a performance test, specifically, the anti-shrinkage agent masterbatch prepared in this embodiment was added to the molding process of the EVA foam material according to a certain ratio to obtain the EVA foam material containing the anti-shrinkage agent. Through comparative tests, it was found that the shrinkage rate of the EVA foam material added with the anti-shrinkage agent of this embodiment at high temperature was significantly reduced, and other physical properties such as elasticity and wear resistance were not affected.

[0063] Example 6

[0064] The anti-shrinkage agent for the sole foam material provided in this embodiment has the following raw material composition: polyolefin elastomer (propylene-based polyolefin elastomer): 20 parts; low-density polyethylene (melt index is 2g / 10min): 50 parts; ethylene-vinyl acetate copolymer (vinyl acetate content is 26%): 20 parts; processing aid (stearic acid): 3 parts; compatibilizer (polyolefin elastomer graft): 7 parts. The preparation method is as follows:

[0065] Accurately weigh the above materials and add them into the high-speed mixer according to the above proportions.

[0066] The mixer speed was set to 600 revolutions per minute and the mixing time was set to 8 minutes to ensure that the various raw materials were mixed evenly to obtain a mixed raw material.

[0067] The obtained mixed raw material is fed into a twin-screw extruder for granulation.

[0068] The front zone temperature of the twin-screw extruder was set to 180°C and the head temperature was set to 190°C.

[0069] The twin-screw speed was set to 35 Hz, the pelletizing speed was set to 22 Hz, and the vacuum degree was set to 0.08 MPa. The anti-shrinkage agent masterbatch for the foaming material was obtained through an extrusion water-cooled pelletizing process.

[0070] The obtained material was subjected to a performance test, specifically, the anti-shrinkage agent masterbatch prepared in this embodiment was added to the molding process of the TPU foam material according to a certain ratio to obtain a TPU foam material containing an anti-shrinkage agent. Through comparative tests, it was found that the dimensional stability of the TPU foam material added with the anti-shrinkage agent of this embodiment at high temperature was significantly improved, and its physical properties such as elasticity and wear resistance were maintained excellent.

[0071] In Examples 5 and 6, by optimizing the raw material composition and adopting a composite formula of polyolefin elastomer, low-density polyethylene and ethylene-vinyl acetate copolymer, good compatibility of the anti-shrinkage agent with the foaming material is achieved, and the effectiveness of the anti-shrinkage agent is improved. During the preparation process, by adjusting the parameters of the twin-screw extruder, such as temperature, rotation speed, etc., the uniformity and stability of the anti-shrinkage agent masterbatch are further improved, thereby improving its dispersibility and effect in the foaming material. The embodiment also adds processing aids and compatibilizers, which not only improves the production efficiency of the anti-shrinkage agent, but also further enhances the compatibility of the anti-shrinkage agent with the foaming material, so that the foaming material after adding the anti-shrinkage agent has better dimensional stability and physical properties at high temperatures.

[0072] The above description is merely an implementation case of the present invention so that professionals in the field can implement or use the present invention. It does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiments based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. An anti-shrinkage agent for use in a sole foaming material, characterized in that: The invention is prepared from the following raw materials: 10-50 parts of polyolefin elastomer, 10-60 parts of linear low-density polyethylene, 10-30 parts of ethylene-vinyl acetate copolymer, 1-10 parts of processing aid and 1-10 parts of compatibilizer; wherein the polyolefin elastomer is selected from vinyl polyolefin elastomer; and the melt index of the linear low-density polyethylene is 1-5 g / 10 min.

2. The anti-shrinkage agent for use in the sole foaming material according to claim 1, characterized in that: The vinyl acetate content of the ethylene-vinyl acetate copolymer is 18-26%.

3. The anti-shrinkage agent for use in the sole foaming material according to claim 1, characterized in that: The processing aid is one or more of zinc stearate, stearic acid or stearic acid amide.

4. The anti-shrinkage agent for use in the sole foaming material according to claim 1, characterized in that: The compatibilizer is a polyolefin elastomer graft.

5. The method for preparing the anti-shrinkage agent for sole foaming material according to any one of claims 1 to 4, comprising the following steps: S1. Accurately weigh various materials, add various raw materials, processing aids and compatibilizers into a high-speed mixer and stir for 2-10 minutes to obtain mixed raw materials; S2, feeding the mixed material into a twin-screw extruder for granulation; S3, set the front zone temperature to 90-220℃, and the head temperature to 150-200℃; S4, set the twin-screw speed to 30 Hz, the pelletizing speed to 20 Hz, the vacuum to 0.08 MPa, extrude and water-cool the pellets to obtain the anti-shrinkage agent masterbatch for the foaming material.

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