KR20200134376A - Composition for shoe soles - Google Patents

Abstract

A composition for shoe soles of the present invention contains a base polymer, a filler, a crosslinking agent, a crosslinking accelerator, a processing agent, and a plasticizer, wherein the base polymer may include a solution styrene-butadiene copolymer and polybutadiene. The present inventors have attempted to manufacture a rubber compound for shoe soles, having properties such as a wear resistance of 150 or more and a hardness of 60-65.

Description

Composition for shoe soles

The present invention relates to a composition for a shoe sole, and more particularly, to a rubber composition for a shoe sole capable of expressing excellent grip, cold resistance, appropriate hardness, abrasion resistance, and tensile strength for use as a shoe sole.

Shoes were made to protect human feet, but the demands for their functions are gradually expanding. Apart from just protecting the feet, it is also required to play a role in preventing various accidents that may appear while walking.As part of that, in order to solve accidents caused by slipping that may occur while walking, a slip resistant outsole is provided. There is a research in progress.

However, if the anti-slip property is improved by a simple rubber compound, it exhibits excellent properties in general ground conditions, but there is a problem that the anti-slip effect is not greater than expected in special ground conditions, such as wet, snowy, or frozen conditions. have.

In addition, as interest in health has increased and active external activities under various climatic conditions, the resulting slipping accidents of pedestrians on the slippery road surface appear more than before, which is a new problem.

In winter, snow, rain, and strong cold freeze all over the road and are easily exposed to falls. Moreover, the elderly often suffer hip joint or vertebral fracture injuries due to falls, requiring more attention. Therefore, it is necessary to develop an elastic material having excellent grip, cold resistance, appropriate strength, abrasion resistance, and hardness to be used for shoe soles that can be worn on snow or ice.

Various embodiments of the present invention are intended to provide a rubber composition for a shoe sole capable of expressing excellent grip, cold resistance, appropriate hardness, abrasion resistance, and tensile strength for use as a shoe sole.

In order to achieve the above object, the composition for a shoe sole of the present invention includes a base polymer, a filler, a crosslinking agent, a crosslinking accelerator, a processing agent and a plasticizer, and the base polymer is a styrene-butadiene copolymer synthesized by solution polymerization ( Solution Styrene-Butadiene Copolymer) and polybutadiene may be included.

The present inventors have a cold resistance that can withstand -60℃, a tensile strength of 15MPa or more, and a friction coefficient that satisfies the Ministry of Labor Notice No. 2008-77 Stability Certification Standard (Glycerin 0,36±0.05, detergent 0.4±0.05), It was intended to produce a rubber compound for shoe soles having a hardness of 150 or more and a hardness of 60-65.

1 is a process flow diagram of a manufacturing method according to an embodiment.

Hereinafter, various embodiments of the present document will be described with reference to the accompanying drawings. The examples and terms used therein are not intended to limit the technology described in this document to a specific embodiment, and should be understood to include various modifications, equivalents, and/or substitutes of the corresponding embodiments.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The composition for a shoe sole of the present invention may include a base polymer, a filler, a crosslinking agent, a crosslinking accelerator, a processing agent and a plasticizer.

The base polymer may include a styrene-butadiene copolymer synthesized through solution polymerization and polybutadiene. The styrene-butadiene copolymer synthesized by solution polymerization may be prepared by solution polymerization using an alkyllithium catalyst. At this time, the styrene-butadiene copolymer may have a styrene content of 15 to 30% and a vinyl content of 60% to 70%. Specifically, the styrene content may be 21%, and the vinyl content may be 65%. Through such a styrene-butadiene copolymer, the cold resistance and friction of the composition for a shoe sole of the present invention may be increased.

Polybutadiene may have a cis-1,4 content of 97% or more. Through such polybutadiene, abrasion resistance, repulsion elasticity, aging resistance, and water resistance of the composition for a shoe sole of the present invention may be increased. Polybutadiene has a glass transition temperature of -100°C, which is lower than that of styrene-butadiene copolymer (glass transition temperature -26°C), so if it contains more polybutadiene, the total glass transition temperature of the prepared compound is lowered, increasing low temperature flexibility and increasing cold resistance. have. In addition, polybutadiene has a higher double bond concentration than styrene-butadiene copolymer, which may increase wear resistance.

The weight ratio of the styrene-butadiene copolymer and the polybutadiene may be from 2:8 to 4:6. Preferably, the weight ratio of the styrene-butadiene copolymer and the polybutadiene may be 3:7. If this weight ratio is satisfied, the properties of the base polymer can be improved. That is, the grip and abrasion resistance of the composition for shoe soles may be increased.

Fillers may be added to reduce cost and improve physical properties. 60 to 80 parts by weight of the filler may be included based on 100 parts by weight of the base polymer. Fillers can include silica and carbon black. Specifically, silica may be included in 40 to 70 parts by weight based on 100 parts by weight of the base polymer. Through this, the frictional force can be increased, and ultimately the gripping force can be improved. Carbon black may be included in 5 to 15 parts by weight based on 100 parts by weight of the base polymer. A silicone-based coupling agent may be included for uniform mixing between the hydrophilic silica and the hydrophobic base polymer.

Finishing agents can be added to improve the appearance of the shoe sole and improve processability. 2 to 8 parts by weight of the processing agent may be included based on 100 parts by weight of the base polymer. Processing agents may include Zinc Oxide and Stearic Acid. Specifically, Zinc Oxide may be included in 1 to 5 parts by weight based on 100 parts by weight of the base polymer. Stearic Acid may be included in 0.5 to 4 parts by weight based on 100 parts by weight of the base polymer. Through these specific parts by weight, it is possible to effectively improve the appearance and workability.

A crosslinking agent and a crosslinking accelerator may be included for crosslinking of a styrene-butadiene copolymer and polybutadiene, which are base polymers having a double bond. A crosslinking agent and a crosslinking accelerator may be included in 2 to 7 parts by weight based on 100 parts by weight of the base polymer. Meanwhile, the crosslinking agent may contain sulfur. Crosslinking accelerators may include N-Cyclohexyl-2-benzothiazole-sulfonamide (CBS) and 1,3-Diphenylguanidine (DPG). In this case, the sulfur may be included in 0.5 to 2.5 parts by weight based on 100 parts by weight of the base polymer. CBS may be included in 0.2 to 1.5 parts by weight based on 100 parts by weight of the base polymer. DPG may contain 0.5 to 3 parts by weight based on 100 parts by weight of the base polymer. Crosslinking of the base polymer can be effectively performed through these specific parts by weight.

Plasticizers can be included to prevent too much hardness while maintaining high tensile strength. Tensile strength and hardness are properties that are proportional to each other. In order to provide softness while maintaining high tensile strength, it is necessary to prevent the hardness from becoming too large. For this, a plasticizer Dioctyl Phthalate (DOP) can be used. Dioctyl phthalate, a plasticizer, may be included in 30 to 40 parts by weight based on 100 parts by weight of the base polymer. High hardness can be prevented while maintaining high tensile strength through these specific parts by weight.

The composition for a shoe sole according to an embodiment of the present invention contains a specific material as described above and has a specific blending ratio, so that it can withstand at -60°C, has excellent cold resistance, and has a tensile strength of 15 MPa or more. In addition, the coefficient of friction satisfies the 2008-77 Stability Certification Standard (Glycerin 0,36±0.05, detergent 0.4±0.05), abrasion resistance of 150 or more, and hardness of 60 to 65.

Hereinafter, the present invention will be described in more detail through examples. These examples are for explaining the present invention more specifically, and the scope of the present invention is not limited to these examples.

<Example>

As a compound manufacturing method for the composition for shoe sole, it was kneaded and manufactured using an open roll mill. Referring to FIG. 1, the polymer was first added, followed by Soviet work for a certain period of time, and then a filler and a processing agent were added, followed by kneading for 15 to 20 minutes. The temperature inside the compound was maintained in the range of 60 to 70 ℃. A crosslinking agent was added to the compound thus prepared, and the compound was kneaded for about 5 to 8 minutes into a sheet having a thickness of 3 to 5 mm.

At this time, the formulation of each component in Examples 1 to 8 is shown in Table 1 below.

Polymer Filler Oil Crosslinking agent SSBR BR Silica CB ZnO S/A DOP S CBS DPG Example 1 30 70 40 7.5 3 2 30 2 1.05 2 Example 2 30 70 40 7.5 3 2 30 2.5 1.35 2 Example 3 30 70 60 10 3 2 30 1.5 0.75 2 Example 4 30 70 60 10 3 2 30 2 1.05 2 Example 5 30 70 60 10 3 2 30 2.5 1.35 2 Example 6 30 70 55 10 3 2 30 1.5 0.75 2 Example 7 30 70 60 10 3 2 30 1.25 0.65 1.75 Example 8 30 70 60 10 3 2 35 1.5 0.75 2

<Experimental Example 1-Tensile strength>

A tensile test for measuring tensile strength was performed on the compositions for shoe soles according to Examples 1 to 8. Tensile test was performed according to KSM 6518 (Physical test methods for vulcanized rubber).

This test was conducted to measure the maximum stress at break (hereinafter, tensile strength), the elongation at break, and the stress at a specific elongation rate of the vulcanized rubber. The test piece was 100 mm in length, 20 mm in length of the parallel portion, 5 mm in width of the parallel portion, and 3 mm or less in thickness of the parallel portion.

The test method is as follows.

The test piece must be accurately fixed so as not to interfere with torsion, grip separation, and other tests during the test. Also, the test piece must be fixed in the tester so that it is perpendicular to the tensile direction.

To measure the tensile strength, read the maximum load until the test piece breaks, and obtain the tensile strength.

The formula for calculating the tensile strength is as follows.

TB: 　Tensile strength (MPa)

FB: Maximum load (N)

A: Cross-sectional area of the test piece (mm2)

<Experimental Example 2 Hardness>

A hardness test for measuring hardness was performed on the composition for shoe soles according to Examples 1 to 8. The hardness test was tested according to KSM 6518 (Physical test methods for vulcanized rubber).

Unless otherwise specified, the hardness test is conducted in one of the following ways.

a) Spring type (A type and D type) hardness test

b) Light load type (Orgen type) hardness test

c) Light load type (Fussey Jones type) hardness test

For type A, specimens with a thickness of 12 mm or more should be used, and those with a thickness of less than 12 mm should be 12 mm or more overlapped.

The test method is as follows.

Place the tester vertically and lightly contact the pressing surface so that the pressing needle is perpendicular to the measurement surface of the test piece. As soon as the specified load is completely transferred, read the scale and obtain the hardness of the test piece. In the case of reading the scale after a certain period of time after contacting the pressing surface, it is preferable to use a suitable auxiliary device made so that the testing machine is held vertical and the pressing needle is perpendicular to the measurement surface before the test. In type A, read the scale after pressing it vertically with a load of 9.807N.

<Experimental Example 3- Grounding force>

The anti-slip performance test (friction coefficient test) for measuring gripping force was performed on the compositions for shoe soles according to Examples 1 to 8. The anti-skid performance test was conducted in accordance with the Ministry of Labor Notice No. 2008-77 Stability Certification Standard (Notification of Obligatory Safety Certification for Protective Equipment).

For the test piece, a shoe keel or artificial foot is used to fix the sample. A smooth stainless steel (sus 304) plate with an average surface roughness of 1.6 µm to 2.5 µm or compression with an average roughness of 14 µm to 18 µm was measured at 10 positions parallel to the sliding motion with a specimen length of 0.8 mm. It was tested on the test surface of ceramic tiles.

The test method is as follows.

Before the test, the outsole of the sample is washed with an aqueous ethanol solution and dried with ambient air.

Remove debris after polishing the outsole with a polishing paper (400 grit size) mounted on the rigid block with the minimum pressure applied.

The floor is washed, dried with an aqueous ethanol solution and applied so that the lubricant consists of a continuous layer of at least 1 mm.

The sample is securely installed on the shoe keel or artificial foot and attached to the tester.

Put the sample down on the test surface, measure the friction force more than 5 times by setting the specified test device and test conditions, calculate the average friction coefficient and use it as a slip resistance measure.

<Experimental Example 4-Abrasion resistance>

An abrasion resistance test for measuring abrasion resistance was performed on the compositions for shoe soles according to Examples 1 to 8. The abrasion resistance test was tested according to KSM 6625 (Testing methods for abrasion of vulcanized rubber (NBS method)).

This test is specified for the abrasion test method of crosslinked rubber by the NBS formula. The test piece shall be of a square with a thickness of 6.3 mm and a side length of 25.4 mm, and must be a large test piece with a length of 2.5 mm and a thickness of 2 mm at both ends for attaching to the tester. Unless otherwise specified, the number of test pieces There should be three, and one should be hung on each hanger to which the specimen is attached.

The test method is as follows.

Test by inserting a test piece of a reference material for wear.

Replace the black test piece, which is the standard for wear, with a new one, rotate the test piece until it wears in the shape of a drum, and then stop it, set the scale and rotation counter of the dial thickness gauge to 0, and rotate it again. When the thickness of 2.54 mm is worn, record the number of rotations. In this way, test three specimens for each hanging specimen, and record the average value (R2).

After that, test the test piece to be tested in the same way, but record the number of rotations (R1) required to wear one test piece by 2.54 mm.

The abrasion resistance test calculation formula is as follows.

AI: Wear resistance (%)

R1: Number of rotations required to wear the test piece to be tested by 2.54 mm

R2: The number of rotations required for the wear reference specimen to wear 2.54 mm

<Experimental Example 5-Cold resistance>

The composition for shoe soles according to Examples 1 to 8 was subjected to a low-temperature impact embrittlement test for measuring cold resistance. The low-temperature impact embrittlement test was carried out in accordance with KSM 6676 (Rubber, vulcanized or thermoplastic-Determination of low temperature properties).

The 50% impact embrittlement temperature and the impact embrittlement limit temperature are determined whether or not the test piece is destroyed when tested under the specified conditions. The test piece was tested in length 26-40 mm, width (6±1) mm, and thickness (2±0.2) mm.

The test method is as follows.

When installing the test piece in the thermostat, fill a sufficient amount of the heat transfer medium so that the test piece is contained at least 25 mm deep from the surface of the heat transfer medium.

Cool the temperature of the thermostat with an appropriate amount of dry ice or liquid nitrogen to the test temperature.

Cool the test piece tongs in advance to the test temperature.

Take the test piece tongs out of the thermostat and quickly insert the test piece into the test piece tongs. The length of the specimen protruding from the specimen clamps should be at least 19 mm. After that, the test piece is installed in a thermostat.

After holding the test piece in an atmosphere of each level of test temperature for 5 minutes, apply one blow at the specified speed with a striking rod, and check whether each test piece is destroyed.

This operation is performed at intervals of 2°C from the temperature at which all of the specimens are destroyed to the temperature at which not all of the specimens are destroyed, and the number of failures at each temperature is recorded. At this point, it is advisable to start the test at a temperature where 50% failure is expected.

The results according to Experimental Examples 1 to 5 are shown in Table 2 below.

The tensile strength
(MPa) Hardness
(Shore A) Grip Wear resistance
(%) Cold resistance ^a)
(-60℃) Example 1 9.7 62 Satisfaction 302 0 Example 2 8.8 64 Satisfaction 307 0 Example 3 18.4 64 Satisfaction 314 0 Example 4 12.6 69 Satisfaction 326 0 Example 5 12.5 71 Satisfaction 317 0 Example 6 13.9 62 Satisfaction 316 0 Example 7 17.1 63 Satisfaction 324 0 Example 8 16.2 62 Satisfaction 321 0

a) The number of specimens destroyed by impact after freezing out of five specimens

Referring to Table 2, it can be seen that all of Examples 1 to 8 exhibit excellent properties. Particularly, in the case of Examples 7 and 8, it was found that the hardness was maintained at a low level while having a very high tensile strength, and abrasion resistance was excellent.

So far, the present invention has been looked at around its preferred embodiments. Those of ordinary skill in the art to which the present invention pertains will be able to understand that the present invention can be implemented in a modified form without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments should be considered from an illustrative point of view rather than a limiting point of view. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope equivalent thereto should be construed as being included in the present invention.

Claims (7)

In the composition for shoe soles comprising a base polymer, a filler, a crosslinking agent, a crosslinking accelerator, a processing agent and a plasticizer,
The base polymer is a composition for shoe soles comprising a styrene-butadiene copolymer synthesized by solution polymerization and polybutadiene. According to claim 1
The styrene-butadiene copolymer has a styrene content of 15 to 30%, a vinyl content of 60% to 70%,
The polybutadiene is a composition for shoe soles having a cis-1,4 content of 97% or more. The method of claim 1,
The filler comprises silica and carbon black,
A composition for shoe soles comprising 40 to 70 parts by weight of silica and 5 to 15 parts by weight of carbon black based on 100 parts by weight of the base polymer. The method of claim 1,
The crosslinking agent contains sulfur,
The crosslinking accelerator includes N-Cyclohexyl-2-benzothiazole-sulfonamide (CBS and 1,3-Diphenylguanidine (DPG),
The sulfur includes 0.5 to 2.5 parts by weight based on 100 parts by weight of the base polymer,
The CBS contains 0.2 to 1.5 parts by weight,
The DPG is a composition for shoe soles containing 0.5 to 3 parts by weight. The method of claim 1,
The processing agent includes Zinc Oxide and Stearic Acid,
The Zinc Oxide contains 1 to 5 parts by weight based on 100 parts by weight of the base polymer,
The Stearic Acid is a composition for shoe soles containing 0.5 to 4 parts by weight. The method of claim 1,
The plasticizer includes Dioctyl phthalate,
A shoe sole composition comprising 30 to 40 parts by weight of the Dioctyl phthalate based on 100 parts by weight of the base polymer. The method of claim 1,
Shoes comprising 60 to 80 parts by weight of the filler, 2 to 7 parts by weight of the crosslinking agent and the crosslinking accelerator, 2 to 8 parts by weight of the processing agent, and 30 to 40 parts by weight of the plasticizer based on 100 parts by weight of the base polymer Composition for outsoles.

Images