JP7300273B2 - Anti-slip footwear sole using fine fiber - Google Patents

Description

TECHNICAL FIELD The present invention relates to an anti-slip footwear sole that has a durable anti-slip effect even on slippery road surfaces such as wet polished stone, in addition to ice surfaces and compacted snow surfaces.

Conventionally, various types of anti-slip footwear soles, such as those containing ceramic particles and those containing vegetable particles such as walnut husks and rice husks, have been proposed as rubber compositions having anti-slip properties on snow and ice surfaces.
Patent Literature 1 discloses an anti-slip footwear sole in which glass fibers are mixed in a matrix of rubber or synthetic resin, and tips of the glass fibers protrude from the surface of the matrix. This footwear sole exhibits anti-slip properties by scratching the surface of snow and ice with each of the glass fibers protruding from the surface. Here, the upper limit of the fiber diameter is set at 0.1 mm or less due to the risk of scratching the floor surface or the like due to the fiber having a high elastic modulus. As an example, FIG. 4B also shows an electron micrograph using an alumina fiber that appears to have a fiber diameter of less than 5 μm. However, the fiber density is increased so as to achieve anti-slip properties (at a tensile modulus E [kgf/mm ² ] and a diameter d [mm], an average density of 1 × 10 ⁴ /(E d) fibers per 1 mm ² In order to meet the above requirements, the finer the fiber diameter, the more the amount added must be increased, and the use of ultrafine fibers, which are not general purpose and relatively expensive, was not realistic from a cost standpoint. In addition, it is not clear that the slip resistance differs depending on the combination of fiber diameters or when the fiber diameter is particularly small.

Patent Document 2 discloses an anti-slip footwear sole in which non-hydrophilic treated natural plant fibers are contained in a matrix of rubber or synthetic resin, and the natural plant fibers are exposed on the surface of the footwear sole. The invention of Patent Document 2 has the problem that if natural plant fibers are used as they are for the sole of anti-slip footwear, elasticity, adhesion to rubber components, durability, etc. are insufficient due to the hydrophilicity and water absorbency of natural plant fibers. On the other hand, natural plant fibers are treated with phenol, isocyanate, etc. to make them non-hydrophilic and improve their durability.

Shoe soles using glass fibers or natural vegetable fibers as in Patent Documents 1 and 2 sometimes adhere snow to the soles when walking on the snow surface. When snow adheres to the sole, the fibers protruding from the surface are covered with snow and do not come into contact with the snow and ice surface, so the anti-slip property is not exhibited.

On the other hand, we focused on the fact that when a water film intervenes on the contact surface between the sole and the ground, such as a wet or frozen surface, slippage is likely to occur. It has been proposed to impart water repellency to the surface (Patent Documents 3 and 4).

In Patent Document 3, in an elastic composition containing an elastic resin and an inorganic filler, a water-repellent film-forming molecule is covalently bonded to the surface of the inorganic filler exposed from the elastic resin to form a water-repellent monomolecule. Forming a membrane is disclosed. Inorganic oxides such as fibrous glass, etc., can be cited as inorganic fillers other than silica particles to prevent falling off, and filaments of micron level to nano level are said to be preferable. This example shows that the contact angle of the tire surface to water was improved by treating the surface of a rubber tire containing glass fibers with a water repellent agent. However, the non-slip property of the tire is not disclosed, and even if the thickness of the glass fiber is disclosed down to the ultra-fine nano-level, it is not clear that the difference in water repellency and anti-slip property depends on the fineness.

Further, Patent Document 4 discloses an elastic composite material containing a base material containing rubber or elastic synthetic resin, glass fiber, and synthetic resin fiber, wherein the synthetic resin fiber has higher water repellency than the glass fiber, and the glass fiber and an elastic composite material in which at least some of the synthetic resin fibers protrude from the surface of the matrix. In this embodiment, a mixed yarn (commingled yarn) containing glass fiber and polypropylene fiber is used in one yarn, and a water-repellent coating is formed on the surface of the glass fiber with a silane coupling agent. It is shown that the dynamic water repellency is high and the formation of a water film is difficult, and the slip resistance on ice is improved. However, this is due to the water repellency of the glass fiber surface and the water repellency of the synthetic resin fiber itself, and the influence of the fineness on the water repellency and slip resistance is not clear.

By the way, as in Non-Patent Document 1, in recent years, research has been conducted on biomimetics, which imitates the excellent functions and shapes of living organisms and utilizes them for the development of high-performance materials. Among them, a water-repellent effect due to a fine uneven structure on the surface is known as a surface exhibiting superhydrophobicity. For example, water droplets slide off when the surface is slightly tilted, as typified by lotus and taro leaves (the so-called “lotus effect”), and rose petals are typified by tilting the surface at 90 degrees. One example is the so-called "petal effect", which has a strong adsorption force so that water droplets do not fall even if it is used. In addition, it is believed that the adhesive strength of fingers, which allows geckos to climb vertical walls and crawl on ceilings, is due to the van der Waals force acting on the surface of fine bristles with a dense hierarchical structure on the fingertips and the wall.
Patent Literature 5 proposes a method for producing a resin molded article, claiming that a fine structure utilizing the lotus effect is excellent for enhancing the water repellency of the surface of a resin molded article.

Here, Patent Document 6 contains a thermoplastic resin, a short glass fiber having an average fiber diameter of 1 to 7 μm and a fiber length before kneading of 300 to 1000 μm, and a fibrous reinforcing material having an average fiber diameter of 7 to 20 μm. A composite forming material is disclosed. Fiber-like reinforcing materials with different diameters are used, one of which is short glass fibers as thin as 1 to 7 μm. However, the water repellency and anti-slip properties due to the surface structure are not clear.

Japanese Utility Model Laid-Open No. 62-21905 Japanese Patent Application Laid-Open No. 2008-188220 Japanese Patent Application Laid-Open No. 2010-229180 JP 2015-172157 A JP 2012-66417 A Japanese Unexamined Patent Application Publication No. 2014-201712

Masatsugu Shimomura, "New Trend of New Generation Biomimetic Material Technology Learned from Biodiversity", Science and Technology Trends, May 2010, Research Center for Science and Technology Trends, National Institute of Science and Technology Policy, Vol.10, No.5, p. . 9-28

In view of such circumstances, the present invention provides a footwear sole containing fibers, which has a synergistic effect of at least two types of fibers having different average fiber diameters to prevent slipping on slippery road surfaces such as snow and ice surfaces and wet polished stones. To provide a footwear sole excellent in durability and durability.

First, the present inventors used fine-diameter fibers having an average fiber diameter of 5 μm or less to give the footwear sole surface S a fine uneven structure, and used a physical water-repellent effect such as the lotus effect or the petal effect. We thought that it might be possible to express water repellency by using However, although no significant difference in water repellency was obtained, it was found that the finer the fiber diameter, the more supple the texture of the fiber, resulting in a significant improvement in anti-slip properties.

That is, the anti-slip footwear sole according to the present invention is an anti-slip footwear sole comprising first fibers F1 and second fibers F2 in a matrix M of rubber or elastic synthetic resin, wherein the average first fiber diameter of said first fibers F1 d _F1 is 5 μm to 600 μm, the average second fiber diameter d _F2 of the second fibers F2 is 5 nm to 5000 nm (that is, 5 μm), and not more than half the average first fiber diameter d _F1 (d _F2 ≤ (d _F1 / 2)), wherein at least part of the tip of the first fiber F1 and at least part of the tip of the second fiber F2 are exposed on the matrix surface S, and the first fiber F1 and the second fiber F2 are exposed from the matrix surface S; It has an uneven structure in which protrusions are formed by protruding two fibers F2 and recesses are formed between the protruding fibers .
Here, the range indicated by X to Y indicates from X to Y or more, and the same applies thereafter.

In addition, in the anti-slip footwear sole according to the present invention, at least one of the first fibers F1 has a first fiber tensile modulus E _F1 of 1×10 ³ kgf/mm ² or more.

In addition, in the anti-slip footwear sole according to the present invention, at least one of the second fibers F2 may have a second fiber tensile modulus E _F2 of 1×10 ³ kgf/mm ² or more.

Further, in the anti-slip footwear sole according to the present invention, at least part of the tips of the first fibers F1 and at least part of the tips of the second fibers F2 protrude in a direction substantially perpendicular to the matrix surface S. ing.

In addition, in the anti-slip footwear sole according to the present invention, the second fiber projection length L _F2 exposed on the matrix surface S is shorter than the first fiber projection length L _F1 and is 2d _F2 to 500 μm as needed. .

In the anti-slip footwear sole of the present invention, at least part of the tips of the first fibers F1 and at least part of the tips of the second fibers F2 are exposed on the matrix surface S, and the unevenness of the first fibers F1 and the second fibers are exposed on the matrix surface S. Due to the uneven structure of the fiber F2, the anti-slip effect is obtained more than the conventional anti-slip footwear sole blended only with the first fiber F1 with a large average fiber diameter, and it is easy to slip on snow and ice surfaces and wet polished stones. Anti-slip footwear that is less slippery on road surfaces and allows safer walking can be obtained. This is due to the synergistic effect of the first fiber F1 and the second fiber F2, which are two types of fibers having different average fiber diameters (d _F1 , d _F2 ). Fine fibers that achieve sufficient durability and have an average secondary fiber diameter d _F2 of 5 nm to 5000 nm (i.e. 5 μm) and less than or equal to half the average primary fiber diameter d _F1 (d _F2 ≤ (d _F1 /2)). It is thought that the flexibility of the second fiber F2 suppresses an increase in the hardness of the sole of the footwear, reduces factors that reduce the anti-slip property, and obtains the scratching effect of the second fiber F2, thereby improving the anti-slip property.

Further, at least one of the first fibers F1 has a first fiber tensile modulus E _F1 of 1×10 ³ kgf/mm ² or more, or at least one of the second fibers F2 has a second fiber tensile modulus E When _F2 is 1×10 ³ kgf/mm ² or more, a high scratching effect due to bending rigidity is sustained, and thus more durable anti-slip properties can be obtained.

Moreover, since at least a portion of the tip of the first fiber F1 and at least a portion of the tip of the second fiber F2 protrude in the substantially vertical direction, it is possible to more effectively obtain anti-slip properties due to the fibers scratching the road surface.

In addition, since the second fiber F2 protrusion length L _F2 is shorter than the first fiber F1 protrusion length L _F1 and is 2d _F2 to 500 μm, the protruding fibers scratch the road surface when walking and have an anti-slip effect. In addition, since durability can be ensured by supporting the external force with the first fiber F1 portion, the anti-slip property of the second fiber F2 is maintained.

1 is a schematic diagram showing the structure of a footwear sole surface S according to the present invention; FIG. FIG. 2 is a schematic diagram of a so-called cantilever for explaining elastic curve equations; (a) is a scanning electron micrograph of the footwear sole surface S in Example 2 of the present invention, and (b) is a further enlarged scanning electron micrograph thereof. 4 is a scanning electron micrograph of the footwear sole surface S in Comparative Example 1 of the present invention. 10 is an EPMA image photograph of the footwear sole surface S in Example 5 of the present invention.

Hereinafter, the anti-slip footwear sole of the present invention will be described while exemplifying its embodiments.

<Matrix M>
The matrix M of the anti-slip footwear sole contains rubber or elastic synthetic resin, and is a material whose main component is rubber or elastic synthetic resin. Examples of rubber include natural rubber, diene rubber such as styrene-butadiene rubber, butadiene rubber, isoprene rubber, nitrile-butadiene rubber, and chloroprene rubber, butyl rubber, ethylene propylene rubber, urethane rubber, silicone rubber, chlorosulfonated rubber, and acrylic rubber. Examples include non-diene rubbers such as rubber and epichlorohydrin rubber, and any of these can be used alone or in combination of two or more. Examples of elastic synthetic resins include resins called thermoplastic elastomers, including styrene-based elastomers, olefin-based elastomers, vinyl chloride-based elastomers, urethane elastomers, ester-based elastomers, and amide-based elastomers. It can be used alone or in combination of two or more. The matrix M may be appropriately selected according to desired physical properties, and natural rubber, styrene-butadiene rubber, butadiene rubber, nitrile-butadiene rubber, and rubbers obtained by blending these rubbers are preferably used.

The rubber or elastic synthetic resin that is the matrix M may contain optional additives such as calcium carbonate, magnesium carbonate, silica (white carbon), particulate fillers such as carbon black, and silane. Coupling agents, sulfur, plasticizers, colorants, softeners, curing agents, antidegradants and the like.

<First fiber F1>
As the first fiber F1, known fibers such as naturally-derived organic fibers, synthetic organic fibers, non-metallic inorganic fibers, and metallic fibers can be used. Its average primary fiber diameter d _F1 is between 5 μm and 600 μm. Naturally-derived organic fibers are preferably, for example, non-hydrophilic treated natural plant fibers as described in Patent Document 2, and particularly preferred are phenol-treated bamboo fibers. Examples of synthetic organic fibers include regenerated cellulose fibers, polyester fibers, polyamide fibers, polyvinyl alcohol fibers, polyacrylonitrile fibers, polypropylene fibers, fluorine fibers, polybutylene succinate fibers, polylactic acid fibers, aromatic amide fibers (polyamide fibers), ultra-high molecular weight polyethylene fibers, polyarylate fibers, PBO fibers, polyimide fibers, and the like. Examples of non-metallic inorganic fibers include glass fibers, rock wool, ceramic fibers, artificial mineral fibers such as whiskers (single crystal fibers), natural mineral fibers such as wollastonite, sepiolite and attapulgite, and carbon fibers. . However, some of these examples include fibers generally less than 5 μm, which would otherwise be suitable only as second fibers F2. Any of these can be used alone or in combination of two or more.

If the average first fiber diameter d _F1 is less than 5 μm, the scratching effect will be insufficient, and if d _F1 is greater than 600 μm, the dispersion in the matrix M will be unsatisfactory, resulting in poor physical properties of the molded bottom. d _F1 is preferably 100 μm or less, except for non-hydrophilic treated natural plant fibers.

The first fiber tensile modulus E _F1 of the first fibers F1 is preferably 1×10 ³ kgf/mm ² or more. Among them, nonmetallic inorganic fibers are preferred, and general-purpose glass fibers and carbon fibers are more preferred as fibrous reinforcing materials. In general, it is considered that an _isotropic material has a high ^flexural modulus when the tensile modulus is ^high . Because it lasts, more durable anti-slip properties can be obtained. Non-metallic inorganic fibers, such as glass fibers and carbon fibers, which are brittle fractured, break appropriately when kneaded with the matrix M, and therefore have the advantage of good kneading workability.

As described in Patent Document 1, the first fibers F1 were obtained by applying a sample containing the first fibers F1 to a matrix M of rubber or elastic synthetic resin with an Akron abrasion tester under a load of 2.72 kg and an inclination of 15°. It is preferable to use a fiber that does not cause bending of the fiber protruding from the matrix surface S or deformation of the tip of the fiber when rotated 1000 times. As a result, it eliminates the deterioration of anti-slip properties due to wearing, and has a continuous anti-slip effect. From this point of view, among organic fibers, fibers that have low abrasion resistance and tend to fibrillate are not preferable.

When the first fibers F1 are glass fibers, chopped strands that are generally commercially available for resin reinforcement are preferred. A chopped strand is obtained by bundling glass fibers having an average fiber diameter of several micrometers to several tens of micrometers with a sizing agent and cutting them into a predetermined length.

The blending amount of the first fibers F1 is preferably 5 to 100 parts by weight with respect to 100 parts by weight of the matrix M. If the compounding amount is less than 5 parts by weight, the exposure on the matrix surface S is small, and the scratching effect and anti-slip property due to friction are insufficient. descend.

<Second fiber F2>
As the second fibers F2, similarly to the first fibers F1, known fibers such as naturally-derived organic fibers, synthetic organic fibers, nonmetallic inorganic fibers, and metal fibers can be used. Its average secondary fiber diameter d _F2 is between 5 nm and 5000 nm (ie 5 μm) and less than or equal to half the average primary fiber diameter d _F1 (d _F2 ≦(d _F1 /2)). Naturally-derived organic fibers include, for example, cellulose nanofibers, chitin/chitosan nanofibers, and bacterial cellulose. Synthetic organic fibers and non-metallic inorganic fibers include the same examples as the first fibers F1, and carbon fibers include carbon nanofibers and carbon nanotubes. Any of these can be used alone or in combination of two or more.

If the average second fiber diameter _dF2 is less than 5 nm, it is difficult to disperse the fibers while they are aggregated, and it is difficult to obtain the effect of using fine-diameter fibers. If _dF2 is larger than 5000 nm (that is, 5 μm), there is no point in distinguishing it as the second fiber F2, and it becomes the first fiber F1.

According to the literature (Toshihito Fujita, Yoji Mukai, "Ultrafine long glass fiber", Journal of the Society of Fiber Science and Technology, Society of Fiber Science and Technology, July 10, 1988, Vol. 44, No. 7, p. The radius of curvature ρ when breaking with
ρ = E d/2σ
Here, σ: breaking stress, E: modulus of elasticity, and d: diameter of rod.
That is, if E/σ is constant, the radius of curvature at break is proportional to the diameter of the rod, indicating that in fiber materials, the smaller the single fiber diameter, the higher the bendability. Therefore, even among fibers with a high elastic modulus, ultrafine (glass) fibers are said to have superior bending abrasion resistance and a supple texture compared to (glass) fibers with a large diameter and the same elastic modulus.

The reason why the second fiber F2 improves the anti-slip property on slippery road surfaces such as snow and ice surfaces and wet polished stones is not clearly understood, but the present inventors presume as follows. ing.
By increasing the addition amount of the first fibers F1 having a larger average first fiber diameter d _F1 and increasing the average density of the first fibers F1 protruding from the matrix surface S (for example, ¹ ×10 ⁴ /(E _F1・d _F1 ) Even if an attempt is made to improve slip resistance, workability and physical properties may deteriorate as described above. For example, when short fibers are added to rubber or elastic synthetic resin, the hardness of the rubber or elastic synthetic resin generally increases. However, if the average second fiber diameter _dF2 is thinner like the second fiber F2, the bendability of the fiber increases and the texture becomes supple. As a result, it is possible to reduce factors that reduce slip resistance, such as reduced adhesion to uneven road surfaces. However, with the second fiber F2 alone, the scratching effect is low because it is flexible, and by using it in combination with the first fiber F1, the first fiber F1 mainly scratches the road surface to obtain anti-slip effect and sufficient durability. realizable. In addition, since d _F2 ≦(d _F1 /2), the difference in flexibility due to the difference in fiber diameter between the first fibers F1 and the second fibers F2 appears effectively. This can also be seen from the elastic curve equation described later in paragraph 0045.

Further, when d _F2 is 5 nm to 5000 nm (that is, 5 μm) and d _F2 ≦(d _F1 /2), fine irregularities of the second fibers F2 can be formed on the matrix surface S around the irregularities of the first fibers F1. It is even conceivable that this fine uneven structure improves the anti-slip properties by adding physical adsorption using the accumulation of van der Waals forces (intermolecular forces) like the adhesive force of a gecko's fingers. .

The blending amount of the second fibers F2 is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the matrix M. If the blending amount is less than 0.1 part by weight, the exposure on the matrix surface S is small and the anti-slip property is hardly improved. In addition, the second fiber F2, which is often relatively expensive due to its thinness, may not only reach a plateau, but even decrease, even if the amount of the second fiber increases, and even if it exceeds 10 parts by weight, the performance Hardly expected to improve. Since the second fiber F2 has a fine _dF2 of 5 nm to 5000 nm (that is, 5 μm), the number of fibers per unit weight is large, and a high fiber density can be obtained even with a small addition.

The second fiber tensile elastic modulus E _F2 of the second fiber F2 is also preferably 1×10 ³ kgf/mm ² or more like the first fiber F1. Examples include synthetic organic fibers, non-metallic inorganic fibers, and metal fibers. Among them, non-metallic inorganic fibers are preferred, and glass fibers and whiskers (single crystal fibers) are more preferred. If E _F2 is 1×10 ³ kgf/mm ² or more, not only the first fiber F1 but also the second fiber F2 can improve the anti-slip property due to the scratching effect due to the bending rigidity, and the durability will be higher. be done. In addition, when the diameter of the fiber is reduced, the bendability becomes higher and the fiber becomes more flexible. Therefore, in order to obtain the scratching effect even with the thinner second fiber F2, it is preferable that the _EF2 (that is, the flexural modulus of elasticity) is high. As for the second fiber F2, the non-metallic inorganic fiber, which causes brittle fracture, also has the advantage of good kneading processability. In addition, since the whiskers (single crystal fibers) contained in the nonmetallic inorganic fibers are also needle-like or short fibrous crystals, they have good kneading processability.

As the glass fiber of the second fiber F2, known glass fiber can be used as long as _dF2 is 5 nm to 5000 nm (that is, 5 μm). In recent years, ultrafine glass wool short fibers have been developed as glass fibers having a smaller fiber diameter than those for conventional resin reinforcement, particularly for high performance in heat insulation, sound absorption, filter applications, etc., and these are preferred. Alternatively, the filaments described in the above-mentioned document "Ultrafine glass filaments" may be used.

The first fiber F1 and the second fiber F2 can be used without any particular surface treatment. It is preferred to treat agents. As the silane coupling agent, various known alkoxysilane compounds can be appropriately selected in consideration of adhesion to the matrix M and the like. In addition, adhesion processes called HRH-based treatments and RFL-based treatments may be used.

In the anti-slip footwear sole of the present invention, at least a portion of the tip of the first fiber F1 and at least a portion of the tip of the second fiber F2 may protrude obliquely or substantially perpendicularly to the matrix surface S. The direction of inclination may be oriented in a fixed direction or may be random. The minimum angle θ formed by the protruding fibers with respect to the matrix surface S is preferably 10° or more, more preferably 30° or more, and is substantially perpendicular (that is, about 90°) is most preferred. If it is substantially vertical, it is possible to more effectively obtain anti-slip properties due to the fibers scratching the road surface. All of the protruding fibers are preferably oriented substantially vertically, but some of them may protrude substantially vertically.

The protruding length of the fibers exposed on the matrix surface S is arbitrary, and the protruding length is not the vertical height to the matrix surface S, but the length in the fiber axis direction. The first fiber protrusion length L _F1 is, for example, preferably 1 μm to 500 μm, more preferably 3 μm to 200 μm, particularly preferably 5 μm to 100 μm. It is thought that by setting the length of the protruding portion within this range, the protruding fibers scratch the road surface while being moderately flexed during walking, thereby obtaining an anti-slip effect as well as sufficient durability. Here, from the experience of the present inventors, it is practically unlikely that L _F1 is longer than 500 μm, except in the case of non-hydrophilized natural plant fibers with large d _F1 . Moreover, the second fiber projection length L _F2 is preferably shorter than the first fiber projection length L _F1 (L _F2 <L _F1 ). However, some of the first fibers F1 may satisfy L _F1 ≦L _F2 . This is because the first fibers F1 protrude more than the second fibers F2, so that the external force can be supported by the first fibers F1 and the durability can be ensured, so it is considered that the anti-slip properties of the second fibers F2 are maintained. is. Furthermore, L _F2 may be less than 1 μm, but is preferably 2d _F2 or more. The aspect ratio d _F2 : L _F2 = 1:2 or more, resulting in a second fiber protrusion length L _F2 , resulting in an uneven surface structure with an anisotropy different from that of the particulate filler of other additives, resulting in fiber deflection. is thought to occur.

Here, only the anisotropy of the projection length L _F2 of the second fiber F2 (surface irregularity structure) has been discussed, but the first fiber F1 and the second fiber F2 move toward the matrix M due to the linear anisotropy of the fiber itself. Since the embedded part of the filler is deep, it is natural that the durability against falling off is higher than that of the particulate filler.

According to the elastic curve equation, the amount of deflection δ of the cantilever shown in FIG. 2 is expressed by the following equation.
δ=PL ³ /3EI
Here, P: load, L: member length, E: Young's modulus (longitudinal elastic modulus, tensile elastic modulus), I: geometrical moment of inertia, and EI: flexural rigidity.
Further, in the case of a member having a circular (cylindrical) cross section, the geometrical moment of inertia I is expressed by the following equation.
I=πd ⁴ /64
Here, d represents the diameter of the circle, and π represents the circumference of the circle.
Therefore, as shown in the following equation, the amount of deflection δ is not only inversely proportional to the Young's moduli of the first fiber F1 and the second fiber F2 (that is, the tensile elastic moduli: E _F1 , E _F2 ), but also the projection lengths (L _F1 , L _F2 ) to the third power and inversely proportional to the diameter (d _F1 , d _F2 ) to the fourth power.
δ=64PL ³ /3πEd ⁴
In order to show the amount of deflection due to complex variables including such powers, not only the fiber diameter difference between the first fiber F1 and the second fiber F2 but also the protrusion length difference is added, and the difference between the first fiber F1 and the second fiber F2 is The scratching effect works in a complicated manner, and it is considered that the combination with the fine second fibers F2 produces an effect.

<Manufacturing method of footwear sole material>
The method of manufacturing the footwear sole material of the present invention is not particularly limited, and it can be manufactured according to a known method or by partially modifying a known method. For example, the following methods are mentioned.
[Method 1]: Fibers oriented substantially perpendicular to matrix surface S (1) First fiber F1 and second fiber F2, components such as sulfur and additives are added to matrix M, and the mixture is rolled or kneaded. The mixture is kneaded to obtain a fiber-containing rubber dough.
(2) By rolling the rubber dough, a rolled rubber dough having fibers oriented in the rolling direction is obtained.
(3) The rolled rubber material is cut and laminated in parallel with each other in the rolling direction.
(4) The laminated rolled rubber material is cut in a direction perpendicular to the rolling direction and in a direction perpendicular to the layered surface. As a result, an unvulcanized rubber material having fibers oriented substantially perpendicularly to the cut surface is obtained.
(5) The cut laminate material is vulcanized and integrated by hot pressing in a mold to obtain a footwear sole material.
(6) Since a rubber layer is formed on the surface of the footwear sole material by hot pressing, one side of the footwear sole material is then scraped off with a grinder to scrape off the surface layer of the matrix M, leaving the footwear sole surface S. to expose the first fiber F1 and the second fiber F2.

Another manufacturing method is as follows. In [Method 2] or [Method 3], the fibers are inclined in a certain direction, and the anti-slip property when moved in the inclined direction is superior to the anti-slip property when moved in the opposite direction, and the anti-slip property is directional. come out. Therefore, by arranging the inclination direction in a specific direction according to the purpose, the anti-slip directionality can be controlled. [Method 4] is an example of its application. Regarding [Method 2] to [Method 4], even though the material is an unvulcanized rubber material, the cutting loss increases.
[Method 2]: Fibers are oriented at an inclination angle θ with respect to the matrix surface S Instead of the step (4) above, the laminated rolled rubber fabric is cut in a direction perpendicular to the rolling direction and at an inclination angle θ with respect to the laminated surface. do. As a result, an unvulcanized rubber material having fibers oriented at an inclination angle θ on the cut surface is obtained. Other steps are performed in the same way.
[Method 3]: Fibers are oriented at an inclination angle θ with respect to the matrix surface S Instead of the step (4) above, the laminated rolled rubber fabric is cut in a direction perpendicular to the laminated surface and at an inclination angle θ with respect to the rolling direction. do. As a result, an unvulcanized rubber material having fibers oriented at an inclination angle θ on the cut surface is obtained. Other steps are performed in the same way.
[Method 4]: Fibers Randomly Tilt with respect to Matrix Surface S Instead of the step (3), the cut rolled rubber fabrics are laminated while being rotated so that the angles in the rolling direction are shifted from each other. Instead of the step (4), the laminated rolled rubber fabric is cut in a direction orthogonal to the laminated surface (in any direction with respect to the rolling direction). As a result, an unvulcanized rubber material is obtained in which the fibers on the cut surface are random between layers and slanted in a fixed direction within each layer. Other steps are performed in the same way.
[Method 5]: A rolled rubber in which the fibers are oriented substantially horizontally with respect to the matrix surface S. The steps (3) and (4) are omitted, and instead of the step (5), the fibers are oriented in the rolling direction. The dough is vulcanized and integrated by hot pressing in a mold parallel to the rolling method. As a result, a footwear sole material having fibers oriented substantially horizontally on the surface is obtained. Other steps are performed in the same way.

When fibers are kneaded into a matrix M of rubber or an elastic synthetic resin to form a compound, if the fiber length is too long, the compound becomes hard and the fibers become entangled, resulting in poor operability. However, non-metallic inorganic fibers such as glass fiber and carbon fiber are brittle and easily broken, and when kneading the material with a roll or kneader, the viscoelastic force and shear force of the rubber fabric shear the fiber length to 1 mm or less. evenly distributed. Synthetic organic fibers that are strong enough not to break should be used as short fibers of 3 mm or less so that they can be easily mixed during material kneading.

Next, examples of the present invention will be described in detail with reference to Table 1 or Table 2 of each formulation and each experimental data, and FIGS. 3 to 5. FIG.

<Production of Examples and Comparative Examples>
[material]
Matrix M: raw rubber (natural rubber/oil-extended styrene-butadiene rubber=60/40 excluding oil).
First fiber F1: A glass fiber chopped strand with an average fiber diameter of 13 μm (hereinafter sometimes referred to as GF13μ) and a glass fiber chopped strand with an average fiber diameter of 23 μm (hereinafter sometimes referred to as GF23μ) at a constant ratio of 1 :1.
Second fiber F2: glass wool fiber with an average fiber diameter of 0.6 μm (hereinafter sometimes referred to as GW0.6 μm), or glass wool fiber with an average fiber diameter of 3.5 μm (hereinafter sometimes referred to as GW3.5 μm) be.).

[Comparative Example 1, Comparative Example 1']
30 parts by weight of GF13μ+GF23μ at a constant ratio of 1:1 was added as a blend containing only the first fiber F1 having a conventional large fiber diameter.
[Example 1-3]
GF13μ+GF23μ was added to 30 parts by weight as the first fiber F1, and GW0.6μ was added as the second fiber F2, and the amount added was varied between 0.5 parts by weight and 3.0 parts by weight.
[Comparative Example 2]
The conventional first fiber F1 having a large fiber diameter was not added, and only 3.0 parts by weight of GW 0.6 μm was added as the second fiber F2.
[Example 4-6]
GF13μ+GF23μ was added to 30 parts by weight as the first fiber F1, and GW3.5μ was added as the second fiber F2, and the amount added was varied between 0.5 parts by weight and 3.0 parts by weight.
[Comparative Example 3]
Neither the first fiber F1 nor the second fiber F2 were added.
[Comparative Example 4-5]
The conventional first fiber F1 having a large fiber diameter was not added, and only GW 3.5 μm was added as the second fiber F2, and the amount added was varied between 15 parts by weight and 30 parts by weight.

[Manufacturing method]
A footwear sole material was made according to the following method.
(1) First fiber F1 and/or second fiber F2 and other additives (however, most of the oil is contained in the oil-extended rubber) are added to 100 parts of raw rubber in the amounts shown in Tables 1 and 2, A fiber-containing rubber dough was obtained by roll kneading. At this time, the first fibers F1 and/or the second fibers F2 were sheared by the viscoelastic force and shearing force of the rubber fabric and dispersed almost evenly, so that there was no problem in kneading.
(2) The fiber-filled rubber fabric was rolled, cut, and laminated in parallel with each other in the rolling direction.
(3) The laminated fiber-containing rubber fabric was cut in the direction perpendicular to the rolling direction and in the direction perpendicular to the lamination surface, and the cut laminate was vulcanized and integrated by hot pressing in a mold to obtain a fiber-containing vulcanized rubber.
(4) One surface of the fiber-containing vulcanized rubber was plowed with a grinder to remove the surface layer of the vulcanized rubber, thereby obtaining a footwear sole material in which the fibers were exposed on the footwear sole surface S.

<Scanning electron micrograph>
In Example 2 (GF+GW0.6μ: 1.5 parts by weight) and Comparative Example 1 (GF only), scanning electron micrographs of the sole surface S of the footwear were taken. The results are shown in FIGS. 3 and 4. FIG.
In FIGS. 3 and 4, unevenness due to particles other than the first fiber F1 or the second fiber F2 is also seen on the footwear sole surface S, but the possibility of white carbon aggregates or the like can be considered. They are particulate and have no anisotropy with an aspect ratio of 1:2 or more.
<EPMA image photo>
In Example 5 (GF+GW 3.5μ: 1.5 parts by weight), a three-dimensional photograph of the footwear sole surface S was taken by EPMA. The results are shown in FIG.
3 (Example 2) and FIG. 5 (Example 5), in the footwear sole material, a part of the tip of the first fiber F1 and a part of the tip of the second fiber F2 are exposed on the footwear sole surface S, and the first It can be seen that the structure has unevenness of the fiber F1 and unevenness of the second fiber F2. Also, it can be seen that the tips of the first fibers F1 and the tips of the second fibers F2 are partially inclined with respect to the footwear sole surface S, but mostly protrude in a substantially vertical direction. Furthermore, the second fiber projection length L _F2 is shorter than the main first fiber projection length L _F1 and is found to be 2d _F2 or more (aspect ratio d _F2 :L _F2 =1:2 or more).

<Slip resistance test>
The anti-slip property was evaluated by the coefficient of slip resistance and the sensory test in the anti-slip property test. The results are also shown in Tables 1 and 2. A series of footwear sole material preparations and a series of slip resistance tests are separately performed in Tables 1 and 2.
The anti-slip property test was carried out in accordance with "17 Slip property test" defined in JIS A 1454:2016 "Methods for testing polymeric flooring materials". For the "slide piece material" which is the piece to be tested, the footwear sole material produced with the composition shown in Tables 1 and 2 was used. As floor surfaces, "wet ice" was evaluated in Table 1, and "wet ice" and "wet polished marble" were evaluated in Table 2.
The slip resistance coefficient is C.I. S. It is indicated by the R value. C. S. The R value is according to the following formula.
C. S. R=Pmax/W
Pmax: maximum tensile force (N)
W: Vertical force (N) = 785N
C. S. As the R value, C.I. S. R is required to be used, and a value of "C.S.R = 0.4 to 0.9" is used as a guidance criterion when walking with shoes on.
In addition, sensory anti-slip evaluation was performed on an icy road surface in Sapporo City, Hokkaido (outside temperature 0° C.) using shoes with the same footwear sole material. The results were indicated by X when slipping occurred, O when satisfactory anti-slip performance was exhibited, and ⊚ when excellent anti-slip performance was exhibited.

<Hardness measurement>
The rubber hardness was measured by the following method in accordance with JIS K 6253:2012 "Vulcanized rubber and thermoplastic rubber-Determination of hardness-".
The tester uses a type A durometer, and a test piece with a thickness of 6 mm or more is brought into contact with a pressure plate so that the indenter is perpendicular to the test piece measurement surface, and the indenter is applied to the test piece with a load of 9.81N. After pressing, I immediately read the scale.

Table 1 compares the anti-slip properties of "wet ice". In Example 1 (0.5 parts by weight), Example 2 (1.5 parts by weight), and Example 3 (3.0 parts by weight) in which GW 0.6 μ was added as the second fiber F2 in addition to the first fiber F1, , compared to Comparative Example 1 in which only the first fiber F1 was added without adding the second fiber F2. S. R value increased. Moreover, as the amount of GW 0.6 μm added in Examples 1 and 2 increased, the C.I. S. Although the R value tended to increase, even if the addition amount of GW 0.6 µm was further increased as in Example 3, the C.I. S. An increase in the R value was suppressed. In this way, in the present example, there is also an interaction between the fibers used, and it was found that the inflection point of the anti-slip property is likely to occur between 0.5 and 3.0 parts by weight of the added amount of GW 0.6μ. .
In Comparative Example 2 (3.0 parts by weight) in which only the second fiber F2 was added without adding the first fiber F1, C.I. S. The R value was remarkably low.
Also in the sensory test, C.I. S. A trend similar to that of the R value was obtained.

Next, from Table 2, first, the results of anti-slip properties in "wet ice" are compared. In Example 4 (0.5 parts by weight) and Example 5 (1.5 parts by weight) in which GW 3.5 μ was added as the second fiber F2 in addition to the first fiber F1, the first The C.I. S. R value increased. However, as Examples 5 and 6 (3.0 parts by weight) and the addition amount of GW 3.5μ further increased, C.I. S. The R value did not increase and tended to decrease slightly, and the value in Example 6 was lower than that in Comparative Example 1'. Thus, it was found that there is likely to be an inflection point in anti-slip properties between 0 and 1.5 parts by weight of GW3.5μ. In Comparative Example 1 in Table 1 and Comparative Example 1' in Table 2, which have the same composition, C.I. S. The reason why the R values are different is that conditions such as "wet ice" surface conditions may be different depending on the time of the experiments conducted separately.
In Comparative Example 3, in which neither the first fiber F1 nor the second fiber F2 was added, C.I. S. The R value was remarkably low.
In Comparative Example 4 (15 parts by weight) and Comparative Example 5 (30 parts by weight) in which only GW 3.5 μm was added as the second fiber F2, C.I. S. Although R increased, it did not reach the value of Comparative Example 1' (30 parts by weight) in which only the first fiber F1 was added, although the added amount was large.
Also in the sensory test, C.I. S. A trend similar to that of the R value was obtained.

Further, from Table 2, the results of anti-slip properties of "wet polished marble" are compared. In Example 5 (1.5 parts by weight) and Example 6 (3.0 parts by weight) in which GW 3.5 μ was added as the second fiber F2 in addition to the first fiber F1, the first fiber F2 was added without adding the second fiber F2. The C.I. S. As the R value increases and the amount added increases, the C.I. S. R-value increased. However, in Example 4 (0.5 parts by weight), Comparative Example 1' and C.I. S. R values were identical.

Also, from Table 2, rubber hardness is compared according to the amount of fiber added. In Comparative Example 5 in which 30 parts by weight of GW 3.5 μ was added as the second fiber F2 without adding the first fiber F1, compared to Comparative Example 3 in which neither the first fiber F1 nor the second fiber F2 was added, Compared to Comparative Example 1′ in which 30 parts by weight of GF13μ+GF23μ were added as the first fibers F1, the increase in rubber hardness was less. Example 4 (0.5 parts by weight), Example 5 (1.5 parts by weight), Example 6 (3.0 parts by weight) in which GW 3.5 μ was changed as the second fiber F2 in addition to the first fiber F1 In this case, although the fiber density should be high even if the second fiber F2 is added in a small amount, the increase in rubber hardness from that of Comparative Example 1' was slight.

Summarizing the anti-slip properties of "wet ice" in a sensory test, the results are as follows. In Example 1-5, in which the second fiber F2 was added in addition to the first fiber F1, excellent anti-slip performance (⊚) was exhibited in sensory anti-slip evaluation on icy road surfaces, and extremely good results were obtained. In Comparative Examples 1 and 1′ in which only the conventional first fiber F1 was added, and in Comparative Examples 4 (15 parts by weight) and Comparative Example 5 (30 parts by weight) in which only the second fiber F2 was added in large amounts, the functional The anti-slip performance was satisfactory (○) in the anti-slip evaluation, but inferior to that of Example 1-5. On the other hand, Comparative Example 2 (3.0 parts by weight) in which only GW 0.6 μm was added as the second fiber F2 without adding the first fiber F1, and a comparison in which neither the first fiber F1 nor the second fiber F2 was added In Example 3, C.I. S. As the R value was as low as less than 0.4, the anti-slip performance in the sensory anti-slip evaluation was also slippery (×), and was completely unsatisfactory.

M. Matrix S Matrix surface, footwear sole surface F1 First fiber F2 Second fiber d _F1 average first fiber diameter d _F2 average second fiber diameter θ Minimum angle that a protruding fiber makes with respect to the matrix surface L _F1 First fiber protruding length L _F2 Second fiber protruding length δ Deflection amount of cantilever beam P Load L Length of cylindrical cantilever d diameter of cylindrical cantilever

Claims (3)

An anti-slip footwear sole comprising first fibers (F1) and second fibers (F2) in a matrix (M) of rubber or elastic synthetic resin,
The average first fiber diameter (d _F1 ) of the first fibers (F1) is 5 μm to 600 μm,
The average second fiber diameter (d F2 ) of the second fibers ( _F2 ) is 5 nm to 5000 nm (that is, 5 μm) and not more than half the average first fiber diameter (d _F1 ) (d _F2 ≤ (d _F1 /2)) and
At least part of the tips of the first fibers (F1) and at least part of the tips of the second fibers (F2) are exposed on the matrix surface (S), and the matrix surface (S) extends to the first fibers (F1 ). and the second fiber (F2) projecting to form projections, and a concave-convex structure in which recesses are formed between the projecting fibers . The anti-slip footwear sole according to claim 1, characterized in that at least one of the first fibers (F1) has a first fiber tensile modulus (E _F1 ) of 1 x 10 ³ kgf/mm ^{2 or} more. The anti-slip footwear sole according to claim 1 or 2, characterized in that at least one of the second fibers (F2) has a second fiber tensile modulus (E _F2 ) of 1×10 ³ kgf/mm ^{2 or} more. .

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