CN115449147A

CN115449147A - Ultra-light foaming material and preparation method thereof

Info

Publication number: CN115449147A
Application number: CN202211157383.4A
Authority: CN
Inventors: 李储民; 杨廉
Original assignee: Qingdao Changjie Technology Co ltd
Current assignee: Qingdao Changjie Technology Co ltd
Priority date: 2022-09-22
Filing date: 2022-09-22
Publication date: 2022-12-09
Anticipated expiration: 2042-09-22
Also published as: CN115449147B

Abstract

The invention discloses an ultralight foaming material and a preparation method thereof, relating to the technical field of chemical foaming materials for shoes, and the key points of the technical scheme are as follows: an ultralight foaming material comprises the following raw materials in parts by weight: 50-90 parts of ethylene-vinyl acetate copolymer; (b) 5-40 parts of cross-linked regenerated resin; (c) 0.3-0.9 parts of peroxide crosslinking agent; (d) 0.01-0.1 parts piperidine nitroxide radical; (e) 2-5 parts of an azo blowing agent; the preparation method of the ultralight foaming material comprises the following steps: s1, preparing regenerated resin, S2, preparing a blend, S3, extruding and granulating the blend to obtain blend particles, and S4, performing injection molding on the blend particles in an injection molding machine, and performing die jumping to obtain the composite material. The invention has the advantages of direct addition of recycled leftover materials, simple processing and excellent performance.

Description

Ultra-light foaming material and preparation method thereof

Technical Field

The invention relates to the technical field of chemical foaming materials for shoes, in particular to an ultralight foaming material and a preparation method thereof.

Background

The conventional sports shoes mainly comprise a vamp, an insole, a middle sole and an outsole, wherein the middle sole is arranged between the outsole and the vamp, the thickness of the middle sole is about 1-2cm, the middle sole plays roles of buffering ground vibration, improving the stability of the shoes and the like, and the middle sole is the part with the highest technological content in shoe materials. Ethylene-vinyl acetate copolymer (EVA) is one of common shoe materials, and the special structural design ensures that the EVA has excellent resilience performance while ensuring light weight in the field of shoe material foaming. Since lighter materials can satisfy more excellent performance of athletes in racing, weight reduction of shoe materials has been an object of continuous pursuit in the industry.

Sustainable development is one of the most important development topics in the world today and is also a goal that is constantly pursued by the industry and academia. In the conventional production process, scraps produced during processing are often regarded as unusable wastes, and are disposed of as fillers after being incinerated or physically crushed. In recent years, with the introduction of the concept of sustainable development, the concepts of "carbon footprint", "carbon emission", etc. have been deeply focused and gradually become the focus of technological development. How to recycle materials such as scrap in industrial processing is also becoming an object of continuous pursuit in the industry. However, it is difficult to obtain the same excellent performance as the new material by simply performing secondary processing on the industrial leftover materials by adding the leftover materials into the new material, which is mainly caused by the problems of degradation of the reclaimed materials, compatibility between the reclaimed materials and the new materials and the like. If the recycled leftover materials and the new materials can be mixed for use and obtain excellent performance, the method is undoubtedly beneficial to solving the problems of sustainable development, circular economy and the like in the industry.

For foaming, a lower material density can be achieved by a higher expansion ratio. However, the expansion ratio of the material cannot be increased without limit because the physical and mechanical properties such as tensile strength or tear properties of the material are significantly reduced as the expansion ratio is increased. Therefore, the EVA foaming formula which can realize high foaming ratio and has excellent physical and mechanical properties is developed, and has important application value and practical significance.

Currently, patent application publication No. CN114369302A, which may be referred to herein, discloses an EVA recycled material closed-cell foam material and a preparation method thereof, and the process requires that carbon black and EVA recycled leftover materials are first processed through banburying, open milling and other forms to obtain a premixed recycled material, and then the premixed recycled material is processed and molded through a second mixing with EVA and other components through banburying. The steps are complicated, and the preparation of the foaming material with other colors except black cannot be realized due to the introduction of carbon black reinforcement.

In the invention, an EVA waste material needs to be crushed to form a crushed material (particle size is less than 1 cm) and then mixed with a new material for the next processing.

The prior patent application published under No. CN113980348A discloses a method for preparing regenerated EVA material, which comprises crushing EVA into particles, and treating by swelling with organic solvent. The method is relatively complex in preparation, needs highly-polluted organic solvent to participate in the process, and has a lot of inconvenience in practical use.

Currently, patent application publication No. CN113502015A may be referred to, and discloses a method for recycling EVA rubber, which includes the processes of crushing, compressing, plasticizing, banburying, granulating, and the like, and then may be added into the formulation of shoe materials for further use.

All the technical documents do not solve the problem that leftover materials in the production process are directly added into a chemical foaming formula to produce the ultralight and high-performance EVA foaming material without special treatment.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide an ultralight foaming material and a preparation method thereof, and the ultralight foaming material has the advantages of capability of directly adding recycled leftover materials, simplicity in processing and excellent performance.

In order to achieve the purpose, the invention provides the following technical scheme: an ultralight foaming material comprises the following raw materials in parts by weight:

(a) 50-90 parts of ethylene-vinyl acetate copolymer;

(b) 5-40 parts of cross-linked regenerated resin;

(c) 0.3-0.9 part of peroxide crosslinking agent;

(d) 0.01-0.1 part of piperidine nitroxide radical;

(e) 2-5 parts of azo foaming agent.

Further, the ethylene-vinyl acetate copolymer has a vinyl acetate content of >18%.

Further, the crosslinked regenerated resin is a crosslinked product of a mixture of vinyl acetate and a polyolefin elastomer, and the mass ratio of the vinyl acetate to the polyolefin elastomer is 1.

Further, the peroxide crosslinking agent includes, but is not limited to, aromatic diacyl peroxides, aliphatic diacyl peroxides, dibasic acid peroxides, bis-2, 4-dichlorobenzoyl peroxide, dicumyl peroxide, di-t-butylperoxyisopropyl benzene, 2, 5-bis (t-butylperoxy) -2, 5-dimethylhexane, lauroyl peroxide, succinic peroxide, cyclohexanone peroxide, and combinations thereof.

Further, the air conditioner is characterized in that, the piperidine nitroxide radicals include, but are not limited to, 2,2,6,6-tetramethylpiperidine-1-oxyl, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-methyl-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl, and mixtures thereof.

Further, the azo foaming agent includes, but is not limited to, azodicarbonamide, 2' -azobisisobutyronitrile, diisopropyl azodicarboxylate, barium azodicarboxylate, diethyl azodicarboxylate, azoaminobenzene, and mixtures thereof or master batches containing the same.

Further, the preparation method of the ultralight foamed material comprises the following steps:

s1, preparing regenerated resin: mixing ethylene-vinyl acetate copolymer and polyolefin elastomer uniformly, extruding and granulating to obtain particles A; injecting the particles A to obtain a device B; crosslinking the device B to obtain a crosslinked device C, cutting and reserving the required part, and crushing the rest part to obtain the crosslinked device C;

s2, preparing a blend: sequentially adding other raw materials according to the weight ratio, uniformly mixing, adding an azo foaming agent and a peroxide crosslinking agent, and continuously mixing to obtain the composite material;

s3, extruding and granulating the blend to obtain blend particles;

s4, carrying out injection molding on the blend particles in an injection molding machine, and (5) jumping the mold to obtain the product.

Further, in step S1, the weight ratio of the ethylene-vinyl acetate copolymer to the polyolefin elastomer is 3.

Further, in step S4, the injection molding parameters are that the screw temperature is 115 ℃ and the mold temperature is 170 ℃, after the injection molding is completed, the mold closing state of the mold is maintained, the pressure is maintained for 5min, and then the mold is instantaneously tripped to release the pressure.

Further, the density of the ultra-light foaming material is 0.05-0.30g/cc.

In conclusion, the invention has the following beneficial effects:

the ultra-light foaming material can directly use recycled leftover materials as raw materials, complex pretreatment is not needed, the preparation method is simple and practical, and the density of the obtained foaming material is 0.05-0.30g/cc, so that the ultra-light foaming material has excellent ultra-light performance.

Drawings

FIG. 1 is a photograph of particles A in a production example of a crosslinked recycled resin according to the present invention;

FIG. 2 is a photograph of a device B in an example of the production of a crosslinked recycled resin according to the present invention;

FIG. 3 is a photograph of a device C according to an example of the production of the crosslinked recycled resin of the present invention, wherein the circled portion is the crosslinked recycled resin.

Detailed Description

The present invention will be described in further detail with reference to examples.

As used throughout this specification, all "percentages" recited herein are weight percentages (wt%), unless the context clearly dictates otherwise.

As used throughout this specification, all "parts" recited herein are parts by weight unless the context clearly dictates otherwise.

As used throughout this specification, unless the context clearly indicates otherwise, all "density" determination methods described in this specification are as follows: the foamed sample was cut into a rectangular parallelepiped having a length of 10cm and a width of 5cm, and the thickness was measured with a vernier caliper and recorded as A cm. The sample was weighed using a balance to give a mass of mg and the density of the sample was calculated by the following formula:

as used throughout this specification, all "tensile strengths" described herein are measured using the ASTM D638 method, unless the context clearly indicates otherwise.

As used throughout this specification, all "tear strength" described herein are measured using the ASTM D624 mode, unless the context clearly indicates otherwise.

The raw material compositions in the preparation examples and examples are shown in table 1.

TABLE 1 raw material List

Name of raw materials	Remarks to	Manufacturer of the product
			EVA	Table plastic 7470M	Table plastic
POE	Tafmer DF610	Japan three well
			Crosslinked regenerated resin	Processing leftover bits and pieces	Chemistry in Korean
Recovering EVA powder	Recovery of EVA powder	Chemistry in Korean
			BIPB	Di-tert-butylperoxy cumene	Fangruida medicine
Piperidine nitroxide radical	4-hydroxy-2, 6-tetramethylpiperidine-1-oxyl radical	Guangzhou Yuandao
			ADC	Azodicarbonamide	Tianjian in Anhui province
ZnO	Zinc oxide	Guangzhou Yuandao
			Zn(St) ₂	Zinc stearate	Guangzhou Yuandada

Preparation example of crosslinked regenerated resin

Physically mixing EVA and POE according to the weight ratio of 3, pouring the mixture into a feeder of a double-screw extruder, controlling the temperature of each barrel of the extruder to be 80 ℃, 100 ℃, 120 ℃, 160 ℃ and 160 ℃ in sequence, carrying out extrusion and bracing, and granulating by using a granulator to obtain particles A;

filling the particles A into a hopper of an injection machine, and performing injection processing while keeping the temperature of a screw of the injection machine at 115 ℃ and the temperature of a mould at 35 ℃ to obtain a device B;

the prepared device B is subjected to electron beam crosslinking (30 KGy, qingdao high-energy electron irradiation Co., ltd.) to obtain a crosslinked device C; and then cutting to remove the part of the device to be reserved, and crushing the rest part to obtain the regenerated resin.

Example 1

Heating the cavity of the internal mixer to 50 ℃ electrically, and then adding 60kg of ethylene-vinyl acetate copolymer (EVA), 40kg of crosslinking regeneration resin, 0.1kg of 4-hydroxy-2, 6-tetramethylpiperidine-1-oxygen radical, 1kg of ZnO and Zn (St) into the cavity of the internal mixer according to the weight parts of the raw materials in sequence ₂ 1kg, mixing while keeping the rotor speed at 20 rpm/min; after the raw materials are uniformly mixed and have consistent color tone, adding 2.5kg of Azodicarbonamide (ADC) and 0.8kg of di-tert-butylperoxy cumene (BIPB), keeping the rotating speed of a rotor at 35rpm/min, continuously mixing for 5min, stopping the rotation of the rotor, and pouring a hopper to obtain a blend;

adding the blend into a single-screw extruder, keeping the screw temperature at 100 ℃, extruding and granulating to obtain blend particles;

adding the blend particles into an injection molding machine, keeping the temperature of a screw at 115 ℃ and the temperature of a mold at 170 ℃ for injection molding, maintaining the mold closing state of the mold after the injection molding is finished, keeping the pressure for 5min, and then instantly jumping to release the pressure to obtain the composite material.

Example 2

The difference from example 1 is that 0.01kg of 4-hydroxy-2, 6-tetramethylpiperidine-1-oxyl radical.

Example 3

The difference from example 1 was that 80kg of ethylene-vinyl acetate copolymer (EVA) and 20kg of crosslinked regenerated resin were used.

Example 4

The difference from example 3 was that 0.5kg of di-t-butylperoxycumene (BIPB) and 0.01kg of 4-hydroxy-2, 6-tetramethylpiperidine-1-oxyl were used.

The compositions of the raw materials and the results of the performance tests of examples 1-4 are shown in Table 2 below.

Table 2 examples 1-4 formulations and performance test results

As can be seen from Table 2, the foamed material of the present invention has a density of 0.22-0.24g/cc and has ultra-light properties, and meanwhile, as can be seen from the test results of tensile strength, elongation at break and tear strength of the examples, the ultra-light foamed material of the present invention has good physical properties.

The raw material compositions and the performance test results of comparative examples 1 to 7 are shown in Table 3.

Wherein comparative example 1 is the use of all new starting materials;

comparative example 2 differs from comparative example 1 in that comparative example 2 adds a crosslinked regenerated resin;

comparative example 3 differs from comparative example 2 in that comparative example 3 adds 4-hydroxy-2, 6-tetramethylpiperidine-1-oxyl;

comparative example 4 differs from comparative example 1 in that comparative example 4 adds recycled EVA powder;

comparative example 5 differs from comparative example 4 in that comparative example 5 increases the amount of recovered EVA powder added;

comparative example 6 differs from comparative example 5 in that comparative example 6 added 4-hydroxy-2, 6-tetramethylpiperidin-1-oxyl;

comparative example 7 is different from comparative example 6 in that comparative example 6 adds a crosslinked regenerated resin and increases the addition amount of BIPB.

TABLE 3 formulations and performance test results for comparative examples 1-7

In the background art part of the invention, some regeneration experiments using recycled EVA powder are discussed, and the recycled EVA powder is also added in the comparative example of the invention for formula research. By comparing comparative example 4, comparative example 5 and comparative example 6, it can be found that when 20 parts of the recycled EVA powder is introduced, although the surface of the foamed material is flat, the tensile strength and tear strength are both considerably reduced compared with comparative example 1. As shown in comparative examples 5 and 6, when the amount of the recovered EVA powder reached 40 parts, a foam having a smooth surface could not be obtained. As shown in comparative example 7, continued addition of more ADC blowing agent to the formulation of comparative example 2 did not result in a foam close to that of comparative example 1, but rather, the sample was too high in pressure and burst therefrom due to the generation of a large amount of gas resulting from too much blowing agent. Therefore, compared with EVA recycled powder, the method can realize the addition of the crosslinked regenerated resin with higher proportion on the premise of maintaining the physical and mechanical properties and the density of the foaming material.

The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications without inventive contribution to the present embodiment as required after reading the present specification, but all of them are protected by patent law within the scope of the present invention.

Claims

1. The ultra-light foaming material is characterized by comprising the following raw materials in parts by weight:

(a) 50-90 parts of ethylene-vinyl acetate copolymer;

(b) 5-40 parts of cross-linked regenerated resin;

(c) 0.3-0.9 part of peroxide crosslinking agent;

(d) 0.01-0.1 part of piperidine nitroxide radical;

(e) 2-5 parts of azo foaming agent.

2. The ultra-light foamed material according to claim 1, wherein the ethylene-vinyl acetate copolymer has a vinyl acetate content of >18%.

3. The ultra-light foamed material according to claim 1, wherein the crosslinked recycled resin is a crosslinked product of a mixture of vinyl acetate and a polyolefin elastomer, and the mass ratio of the vinyl acetate to the polyolefin elastomer is 1.

4. The ultra light foamed material of claim 1 wherein the peroxide crosslinking agent includes, but is not limited to, aromatic diacyl peroxides, aliphatic diacyl peroxides, dibasic acid peroxides, bis-2, 4-dichlorobenzoyl peroxide, dicumyl peroxide, di-t-butylperoxycumyl, 2, 5-bis (t-butylperoxy) -2, 5-dimethylhexane, lauroyl peroxide, succinic peroxide, cyclohexanone peroxide, and combinations thereof.

5. The ultra-light foam of claim 1, wherein the piperidine nitroxide radicals include, but are not limited to, 2,2,6,6-tetramethylpiperidine-1-oxyl, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-methyl-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl, and mixtures thereof.

6. The ultra-light foaming material of claim 1, wherein the azo foaming agent comprises, but is not limited to, azodicarbonamide, 2' -azobisisobutyronitrile, diisopropyl azodicarboxylate, barium azodicarboxylate, diethyl azodicarboxylate, azoaminobenzene, mixtures thereof, or master batches containing the same.

7. The method for preparing an ultralight foamed material according to any one of claims 1 to 6, comprising the steps of:

s1, preparing regenerated resin: mixing ethylene-vinyl acetate copolymer and polyolefin elastomer uniformly, extruding and granulating to obtain particles A; injecting the particles A to obtain a device B; crosslinking the device B to obtain a crosslinked device C, cutting and reserving a required part, and crushing the rest part to obtain the crosslinked device C;

s3, extruding and granulating the blend to obtain blend particles;

and S4, performing injection molding on the blend particles in an injection molding machine, and performing die jumping to obtain the composite material.

8. The method for preparing an ultralight foamed material according to claim 7, wherein in the step S1, the weight ratio of the ethylene-vinyl acetate copolymer to the polyolefin elastomer is 3.

9. The method for preparing the ultra-light foaming material of claim 7, wherein in step S4, the injection molding parameters are the screw temperature of 115 ℃ and the mold temperature of 170 ℃, and after the injection molding is completed, the mold closing state is maintained, the pressure is maintained for 5min, and then the mold is instantaneously tripped to release the pressure.