CN111154170A - EVA sole and preparation method thereof - Google Patents

Abstract

The invention discloses an EVA sole and a preparation method thereof, wherein the EVA sole comprises the following raw materials, by weight, 60-70 parts of EVA; 8-10 parts of OBC; 12-15 parts of POE; 1-2 parts of an AC foaming agent; 1-2 parts of a crosslinking agent; 2-3 parts of an activating agent. The OBC has good heat resistance, high elasticity and good processability, and can provide excellent rebound resilience for an EVA foaming system, so that the EVA sole has high elasticity and is not easy to compact. Can further improve the resilience performance of EVA sole through adding POE, and can reduce material surface crystallization rate, overcome the problem that traditional EVA foaming shoes material surface corrugates easily, improve the aesthetic property of product. In addition, the OBC molecules and the POE molecules inevitably form tangles in a three-dimensional space, and the tangles can limit the movement of the macromolecular chain segments like chemical crosslinking, so that the EVA sole is further difficult to compact and wrinkle, and the service performance and the aesthetic property are ensured.

Description

EVA sole and preparation method thereof

Technical Field

The invention relates to the technical field of shoes, in particular to an EVA sole and a preparation method thereof.

Background

Ethylene-vinyl acetate copolymer (EVA) foamed soles are widely used for manufacturing various soles because of the advantages of lightness, good flexibility, comfortable wearing, difficult wrinkling, good elasticity and the like.

Chinese patent with publication number CN103242584B discloses a wear-resistant EVA sole material, which comprises the following components in percentage by mass: 65-85% of EVA (ethylene-vinyl acetate), 5-10% of wear-resistant agent, 0.5-5% of light stabilizer, 5-15% of inorganic filler with the particle size of less than or equal to 200nm, 1-3% of foaming agent, 0.5-2% of cross-linking agent and 1-3% of dispersing lubricant, wherein the wear-resistant agent consists of ethylene-vinyl acetate copolymer and ultrahigh molecular weight organosilicon polymer, and the mass percentages of the components are as follows: 50-60% of ethylene-vinyl acetate copolymer, 40-50% of ultrahigh molecular weight organic silicon polymer, and 15-28% of vinyl acetate in the ethylene-vinyl acetate copolymer by mass percentage. The EVA shoe sole material is better in wear resistance, evenness of a material system and surface smoothness.

The EVA sole has the main advantages of light weight and certain shock absorption performance even if air cushions are not added, but has the defects of poor wear resistance and poor resilience, and is easy to trample and lose the good shock absorption performance.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide the EVA sole which has the advantage of good rebound resilience and good wear resistance.

In order to achieve the purpose, the invention provides the following technical scheme:

an EVA sole comprises the following raw materials in parts by weight,

60-70 parts of EVA;

8-10 parts of OBC;

12-15 parts of POE;

1-2 parts of an AC foaming agent;

1-2 parts of a crosslinking agent;

2-3 parts of an activating agent.

By adopting the technical scheme, the density of the EVA is usually 0.92g/cm³The rubber has good flexibility and elasticity, high tensile property, high shock resistance, namely high buffering performance and strong toughness; the air-conditioning agent is suitable for various climates and environments, and can resist the lowest air temperature of-58 ℃; simultaneously has good ozone resistance, good processing performance and coloring performance, and can be well blended with the filler; the sound insulation and heat insulation effects of the closed cell structure are good; can be applied to the environment of moisture, acid, alkali and salt, and has the advantages of antibiosis, no toxicity, no pollution and the like.

The polyolefin block copolymer (OBC) has good heat resistance, high elasticity and good processability, can provide excellent rebound resilience for an EVA foaming system, can effectively control shrinkage and keep stable dimension, so that the EVA sole has high elasticity and is not easy to compact, and the service life is prolonged.

The ethylene-octene copolymer (POE) is a polyolefin elastomer material prepared from ethylene and octene, the polyethylene is a crystalline material, but because the octene in a molecular chain breaks the crystallization of part of the polyethylene, the octene chain segment and the polyethylene chain segment broken by the crystallization form an elastic soft segment together, and the polyethylene crystalline segment forms a hard segment which plays the role of a physical crosslinking point, so that the POE has the property of an elastomer. Can further improve the resilience performance of EVA sole through adding POE, and can reduce material surface crystallization rate, overcome the problem that traditional EVA foaming shoes material surface corrugates easily, improve the aesthetic property of product.

In addition, the OBC molecules and the POE molecules inevitably form tangles in a three-dimensional space, and the tangles can limit the movement of the macromolecular chain segments like chemical crosslinking, so that the EVA sole is further difficult to compact and wrinkle, and the service performance and the aesthetic property are ensured.

The foaming agent can generate a certain amount of gas at a certain temperature, and the gas can be rapidly diffused in the EVA system to form a porous structure, so that the EVA system has the advantages of light weight and good elasticity. The AC foaming agent can be rapidly decomposed within the temperature range of 195-200 ℃, the gas forming amount is about 220-250ml/g, and the AC foaming agent has the advantages of large gas forming amount, easy dispersion in a matrix, low price, no toxicity and the like. The molecular structure of the high molecular material is like a long line, the high molecular material is low in strength and easy to break without crosslinking, and has no elasticity, and the crosslinking agent has the function of generating chemical bonds among linear molecules to enable the linear molecules to be mutually connected to form a net structure so as to improve the strength and the elasticity of the system.

Further, DCP is used as the crosslinking agent.

By adopting the technical scheme, the dicumyl peroxide (DCP) has good crosslinking effect, and simultaneously, the EVA foam material can form fine and uniform cells, and the heat resistance and the weather resistance of the product are improved.

Further, the activator is composed of zinc oxide, zinc stearate, and stearic acid.

By adopting the technical scheme, the main activation effect of the zinc oxide can reduce the decomposition temperature of the AC foaming agent by about 20-50 ℃, and the activation principle is as follows: in the zinc-based compound, zinc ionThe sub-periphery electronic arrangement mode is 4S²4P²The AC blowing agent has a molecular structure with atoms such as N, O having lone pair electrons. According to the theory of Lewis acid-base coordination, lone-pair electrons on N, O enter the empty orbit of zinc ions to form a '-N-C-' pi bond, and due to loss of the lone-pair electrons, an '-N-C-' electron cloud flows towards two sides, the overlapping degree of the electron cloud at the middle position is reduced, so that the '-N-C-' bond is weakened and then is broken, and the decomposition of the AC foaming agent is activated. The zinc stearate and the stearic acid can also reduce the decomposition temperature of the AC foaming agent to a certain extent, but the cooling effect is not obvious as that of the zinc oxide, and the zinc stearate and the stearic acid are mainly used for playing an auxiliary role, wherein the stearic acid is also beneficial to demoulding.

Further, the activator is composed of, by weight, 1.2 parts of zinc oxide, 0.7 parts of zinc stearate, and 0.5 parts of stearic acid.

By adopting the technical scheme, the crosslinking agent DCP used by the EVA foaming material has better crosslinking effect within the temperature range of 150-157 ℃, the AC foaming agent used usually starts to decompose within the temperature range of 195-200 ℃, and the decomposition temperature is obviously dozens of degrees higher than the crosslinking temperature of DCP. If the temperature is adjusted to be near the decomposition temperature of the AC foaming agent during foaming, the EVA may be depolymerized due to overhigh temperature; in order to avoid depolymerization, the temperature is adjusted to be near the crosslinking temperature of the DCP, and the AC blowing agent is not sufficiently decomposed due to insufficient temperature, thereby resulting in insufficient EVA foaming. The activating agent with the proportion not only can reduce the decomposition temperature of the AC foaming agent, but also can provide good reinforcing and lubricating effects, and the quality of the product is further improved while the processability is improved.

Further, the raw materials comprise 1-3 parts of carbon-nine petroleum resin by weight.

By adopting the technical scheme, the carbon nine resin is added, so that the friction coefficient of the EVA composite foaming material can be obviously improved, and the carbon nine resin contains some rigid molecular chain structures, so that the carbon nine resin has good compatibility with EVA, and the carbon nine resin can also improve the tensile strength of soles. In addition, the carbon nine resin also has good adhesion, and can improve the entanglement of OBC molecules and POE molecules so as to ensure the rebound effect.

Further, the raw material comprises 5-6 parts by weight of naphthenic oil.

By adopting the technical scheme, the naphthenic oil has high viscosity and low pour point, the mechanical property and the cold resistance of the foaming system can be enhanced when the naphthenic oil is filled into the foaming system, and the slip resistance of the sole can be improved while the processability is improved.

Further, the raw materials comprise 2-4 parts of PFPE (Poly-butylenes ether PE) by weight, and the polymerization degree of the PFPE is within 100.

By adopting the technical scheme, the perfluoropolyether (PFPE) has good lubricating property, the EVA foaming system can cause the processing property of the system to be reduced under the tackifying effect of the carbon nine resin and the entanglement of the OBC molecules and the POE molecules, and the added perfluoropolyether can play the roles of softening and lubricating, so that the components can be fully dispersed in the system, and the processing efficiency and the product quality can be ensured. In addition, the perfluoropolyether has higher volatility and is volatilized continuously in the preparation process, so that the processing performance of the EVA foaming composite system can be improved after the perfluoropolyether is added, and a negative effect cannot be generated for a final product.

The invention also aims to provide a preparation method of the EVA sole, which comprises the following steps:

s1, heating naphthenic oil to 120-125 ℃, adding carbon nine resin, stirring until the carbon nine resin is in a transparent viscous state, obtaining a slip-stopping agent, and cooling for later use;

s2, preheating a double-roll mill to 90-100 ℃, and adding EVA granules;

s3, adding zinc oxide, zinc stearate and stearic acid when the EVA is melted and wrapped, and mixing for 5-6 min;

s4, adding a slip agent, an AC foaming agent and a DCP crosslinking agent, and mixing for 6-8 min;

s5, adding OBC, POE and PFPE, mixing for 7-8min, and taking out;

s6, cutting the sheet, placing the cut sheet into a preheated mold, placing the mold on a flat vulcanizing instrument, and foaming for 14-15h at the temperature of 165-170 ℃ and the mold pressing pressure of 10 MPa;

s7, placing the foamed sheet in an oven at 100-105 ℃ for baking until the sheet shrinks to a similar size, and taking out the sheet to obtain the anti-slip sole.

In conclusion, the invention has the following beneficial effects:

1. the polyolefin block copolymer (OBC) has good heat resistance, high elasticity and good processability, can provide excellent rebound resilience for an EVA foaming system, can effectively control shrinkage and keep stable dimension, so that the EVA sole has high elasticity and is not easy to compact, and the service life is prolonged. The ethylene-octene copolymer (POE) is a polyolefin elastomer material prepared from ethylene and octene, the polyethylene is a crystalline material, but because the octene in a molecular chain breaks the crystallization of part of the polyethylene, the octene chain segment and the polyethylene chain segment broken by the crystallization form an elastic soft segment together, and the polyethylene crystalline segment forms a hard segment which plays the role of a physical crosslinking point, so that the POE has the property of an elastomer. Can further improve the resilience performance of EVA sole through adding POE, and can reduce material surface crystallization rate, overcome the problem that traditional EVA foaming shoes material surface corrugates easily, improve the aesthetic property of product.

2. The OBC molecules and the POE molecules inevitably form tangles in a three-dimensional space, and the tangles can limit the movement of the macromolecular chain segment like chemical crosslinking, so that the EVA sole is further difficult to compact and wrinkle, and the service performance and the aesthetic property are ensured.

3. The carbon nine resin is added to obviously improve the friction coefficient of the EVA composite foaming material, and the carbon nine resin contains a plurality of rigid molecular chain structures, so that the carbon nine resin has good compatibility with EVA, and can also improve the tensile strength of the sole. In addition, the carbon nine resin also has good adhesion, and can improve the entanglement of OBC molecules and POE molecules so as to ensure the rebound effect.

4. Perfluoropolyether (PFPE) has good lubricating property, the EVA foaming system can cause the processing property of the system to be reduced under the tackifying effect of carbon nine resin and the entanglement of OBC molecules and POE molecules, and the added perfluoropolyether can play the roles of softening and lubricating, so that all components can be fully dispersed in the system to ensure the processing efficiency and the product quality. In addition, the perfluoropolyether has higher volatility and is volatilized continuously in the preparation process, so that the processing performance of the EVA foaming composite system can be improved after the perfluoropolyether is added, and a negative effect cannot be generated for a final product.

Drawings

FIG. 1 is a flow chart of a method provided by the present invention.

Detailed Description

The present invention will be described in further detail with reference to the following drawings and examples.

Examples

Example 1

The EVA shoe sole comprises the raw material components in parts by weight shown in Table 1.

As shown in fig. 1, the preparation method of the sole comprises the following steps:

s1, taking the naphthenic oil 4010, heating to 125-;

s2, preheating a double-roll mill to 90-100 ℃, and adding EVA 400W granules;

s3, adding zinc oxide, zinc stearate and stearic acid when the EVA is melted and wrapped, and mixing for 5-6 min;

s4, adding a slip agent, an AC foaming agent and a DCP crosslinking agent, and mixing for 6-8 min;

s5, adding OBC 9530 (Dow, USA), POE 8137 (Dow, USA) and PFPE (degree of polymerization within 100), mixing for 7-8min, and taking out;

s6, cutting the sheet, placing the cut sheet into a preheated mold, placing the mold on a flat vulcanizing instrument, and foaming for 14-15h at the temperature of 165-170 ℃ and the mold pressing pressure of 10 MPa;

s7, placing the foamed sheet in an oven at 100-105 ℃ for baking until the sheet shrinks to a similar size, and taking out the sheet to obtain the anti-slip sole.

Example 2

The difference from example 1 is that the raw material components are shown in table 1 in parts by weight.

Example 3

The difference from example 1 is that the raw material components are shown in table 1 in parts by weight.

Example 4

The difference from example 1 is that the raw material components are shown in table 1 in parts by weight.

Example 5

The difference from example 1 is that the raw material components are shown in table 1 in parts by weight.

Comparative example

Comparative example 1

The difference from example 1 is that the raw material components are shown in table 1 in parts by weight.

Comparative example 2

The difference from example 1 is that the raw material components are shown in table 1 in parts by weight.

Comparative example 3

The difference from example 1 is that the raw material components are shown in table 1 in parts by weight.

Performance test

And (3) testing the friction coefficient: according to the standard ASTMF 1677-05, a certain external force is applied to each group of test samples, so that the test samples and the simulated pavement generate horizontal component force and vertical component force, and the friction coefficient of the test samples is evaluated according to the stress balance analysis of physics. The average of the maximum value at which slipping did not occur and the minimum value at which slipping occurred was taken as the static friction coefficient of the sample, and the test results are shown in table 2.

And (3) testing tensile strength: the tensile strength and elongation at break of each set of test specimens were tested with reference to GB/T528-.

And (3) resilience testing: the rebound resilience is tested by using a GT-7042-RE type impact elasticity tester, and the test results are shown in Table 2.

TABLE 1, prescription table

	Example 1	Example 2	Example 3	Example 4
					EVA	60	65	70	65
OBC	8	9	10	9
					POE	12	13	15	13
AC foaming agent	1	1.5	2	1.5
					DCP crosslinking agent	1	1.5	2	1.5
Zinc oxide	1.2	1.2	1.2	1.2
					Zinc stearate	0.7	0.7	0.7	0.7
Stearic acid	0.5	0.5	0.5	0.5
					Carbon nine resin	1	2	3	/
Naphthenic oil	5	5	6	5
					PFPE	2	3	4	3

TABLE 1 continuation

	Example 5	Comparative example 1	Comparative example 2	Comparative example 3
					EVA	65	65	65	65
OBC	9	/	/	9
					POE	13	/	13	/
AC foaming agent	1.5	1.5	1.5	1.5
					DCP crosslinking agent	1.5	1.5	1.5	1.5
Zinc oxide	1.2	1.2	1.2	1.2
					Zinc stearate	0.7	0.7	0.7	0.7
Stearic acid	0.5	0.5	0.5	0.5
					Carbon nine resin	2	/	2	2
Naphthenic oil	5	/	5	5
					PFPE	/	/	3	3

TABLE 2

	Coefficient of friction	Tensile Strength (MPa)	Rebound resilience (%)
				Example 1	0.54	4.2	62
Example 2	0.56	4.3	62
				Example 3	0.57	4.6	63
Example 4	0.49	3.9	60
				Example 5	0.55	4.2	62
Comparative example 1	0.43	3.4	52
				Comparative example 2	0.53	3.9	57
Comparative example 3	0.51	3.7	56

In conclusion, the carbon nine resin, the OBC and the POE can improve the friction coefficient of the EVA foaming product; the OBC and the POE can improve the rebound rate of the EVA foaming product, and the OBC and the POE have a synergistic effect; the PFPE can slightly improve various performances of the EVA foaming product.

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 of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.

Claims (8)

1. An EVA sole, its characterized in that: the raw materials comprise the following components in parts by weight,

60-70 parts of EVA;

8-10 parts of OBC;

12-15 parts of POE;

1-2 parts of an AC foaming agent;

1-2 parts of a crosslinking agent;

2-3 parts of an activating agent.

2. The EVA shoe sole according to claim 1, characterized in that: the cross-linking agent adopts DCP.

3. The EVA shoe sole according to claim 1, characterized in that: the activator consists of zinc oxide, zinc stearate and stearic acid.

4. The EVA shoe sole according to claim 2, characterized in that: the activator consists of 1.2 parts by weight of zinc oxide, 0.7 part by weight of zinc stearate and 0.5 part by weight of stearic acid.

5. The EVA shoe sole according to claim 1, characterized in that: the raw materials comprise 1-3 parts of carbon-nine petroleum resin by weight.

6. The EVA shoe sole according to claim 1, characterized in that: the raw material comprises 5-6 parts of naphthenic oil by weight.

7. The EVA shoe sole according to claim 1, characterized in that: the raw materials comprise 2-4 parts of PFPE (Poly-butylenes ether PE) by weight, and the polymerization degree of the PFPE is within 100.

8. A method for preparing EVA soles according to any one of claims 1 to 7, characterized in that: comprises the following steps of (a) carrying out,

s1, heating naphthenic oil to 120-125 ℃, adding carbon nine resin, stirring until the carbon nine resin is in a transparent viscous state, obtaining a slip-stopping agent, and cooling for later use;

s2, preheating a double-roll mill to 90-100 ℃, and adding EVA granules;

s3, adding zinc oxide, zinc stearate and stearic acid when the EVA is melted and wrapped, and mixing for 5-6 min;

s4, adding a slip agent, an AC foaming agent and a DCP crosslinking agent, and mixing for 6-8 min;

s5, adding OBC, POE and PFPE, mixing for 7-8min, and taking out;

s6, cutting the sheet, placing the cut sheet into a preheated mold, placing the mold on a flat vulcanizing instrument, and foaming for 14-15h at the temperature of 165-170 ℃ and the mold pressing pressure of 10 MPa;

s7, placing the foamed sheet in an oven at 100-105 ℃ for baking until the sheet shrinks to a similar size, and taking out the sheet to obtain the anti-slip sole.

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