JP6964966B2 - Rubber members, their manufacturing methods, and tires - Google Patents

Description

The present invention relates to a rubber member, a method for manufacturing the same, and a tire.

Since the regulation of studded tires, various studies have been conducted to improve the braking performance and drivability of tires on icy and snowy road surfaces. For example, in Japanese Patent Application Laid-Open No. 2014-227487 (Patent Document 1), a modified natural rubber obtained by removing a non-rubber component to make it highly pure and adjusting the pH of the rubber component to a predetermined range by treatment with an acidic compound or the like. It has been proposed that by using a filler such as carbon black, it is possible to improve the reinforcing property and improve the on-ice performance required for a studless tire.

Japanese Unexamined Patent Publication No. 2014-227487

However, since the above-mentioned conventional technique aims to adjust the pH of the rubber component to suppress the decrease in molecular weight during storage, there is a limit to drastically improving the on-ice performance of the tire. be.

Therefore, an object of the present invention is to provide a rubber member capable of improving the performance of a rubber article on ice when used for a rubber article such as a tire. Another object of the present invention is also to provide a method for manufacturing a rubber member, which can obtain a rubber member capable of improving the performance of a rubber article such as a tire on ice. Furthermore, an object of the present invention is also to provide a tire having improved performance on ice.

That is, the rubber member of the present invention is a rubber member having a water thickening substance, and a plurality of minute recesses are present on the surface of the rubber member, and the water thickening substance is applied to the inner surface of the minute recesses. The water thickening substance is arranged so that the average coverage of the water thickening substance on the inner surface of the micro-concave is 10% or more, and the water thickening substance has a concentration of 23% by mass. When the dispersion was prepared, the viscosity of the aqueous dispersion measured by a cone plate type viscous meter at any shear rate of 25 ° C. and 0.01 / s to 0.1 / s was 20 Pa · s. It is characterized by being defined as the above substances. According to the rubber member of the present invention, when used for a rubber article such as a tire, it is possible to improve the performance of the rubber article on ice.

It is preferable that the rubber member of the present invention further has a plurality of microcavities inside, and the water thickening substance is also arranged on the inner surface of the microcavities. Such a rubber member is a rubber member. It can be suitably produced by using a rubber composition obtained by blending a foaming agent and a water-thickening substance-containing organic fiber containing a water-thickening substance and a resin with respect to the rubber component. According to this configuration, the rubber member can bring high performance on ice to the tire or the like for a long period of time, and it is not necessary to use an excessive amount of the water thickening substance.

Further, in the rubber member of the present invention, it is preferable that the water thickening substance has a hydroxyl group. Thereby, the performance on ice of the rubber article can be further improved.

Further, in the rubber member of the present invention, it is preferable that the water thickening substance is arranged on the inner surface of the minute recesses by coating, spraying or impregnating. In such a rubber member, a larger amount of the water-thickening substance is arranged on the inner surface of the minute recesses than in the case where the water-thickening substance is arranged by blending, and in particular, the performance on ice at the initial stage of use of a tire or the like is significantly improved. Can be done.

The method for producing a rubber member of the present invention is the above-mentioned method for producing a rubber member, and is characterized by including a step of applying a water thickening substance to minute recesses formed on the surface of vulcanized rubber. .. According to the method for manufacturing a rubber member of the present invention, it is possible to obtain a rubber member capable of improving the performance of a rubber article such as a tire on ice. Further, in such a manufacturing method, the water-thickening substance can be more easily arranged on the inner surface of the micro-concave than when the water-thickening substance is arranged by blending, and the water-thickening substance can be easily arranged on the inner surface of the micro-concave. The amount of the water thickening substance arranged can be controlled.

The tire of the present invention is characterized in that the above-mentioned rubber member is provided in the tread portion. According to the tire of the present invention, the performance on ice is improved.

According to the present invention, it is possible to provide a rubber member capable of improving the performance of a rubber article on ice when used for a rubber article such as a tire. Further, according to the present invention, it is possible to provide a method for manufacturing a rubber member, which can obtain a rubber member capable of improving the performance of a rubber article such as a tire on ice. Further, according to the present invention, it is possible to provide a tire having improved performance on ice.

FIG. 5 is a schematic cross-sectional view showing the vicinity of the surface of the tread portion of an example tire as an embodiment of the rubber member of the present invention. It is a schematic cross-sectional view which shows the surface and the inside of the tread part of the tire of one example as one Embodiment of the rubber member of this invention. It is a figure which shows typically the image by SEM of the surface of the rubber member of one Embodiment of this invention. It is a figure which shows typically the image by SEM of the surface of the rubber member of one comparative example.

(Rubber member)
Hereinafter, the rubber member of the present invention will be described in detail as an example based on the embodiment.
The tread portion 1 of an example tire as an embodiment of the rubber member of the present invention shown in FIG. 1 can be manufactured by using a rubber composition containing a rubber component and any other component. A plurality of micro-recesses 2 are present on the surface thereof, and a water thickening substance 3 is arranged on the inner surface of each of the micro-recesses 2.
In the present invention, the "water thickening substance" is 0 at 25 ° C. of the aqueous dispersion measured by a cone plate type viscometer when the aqueous dispersion is prepared so that its concentration is 23% by mass. It is defined as a substance having a viscosity of .01 / s to 0.1 / s at an arbitrary shear rate of 20 Pa · s or more.
Further, when the rubber member has a surface that cannot come into contact with an external factor such as a road surface during use, the "surface of the rubber member" in the present invention does not include the surface that cannot come into contact with the rubber member.

Generally, for example, when a car travels on an ice-snow road surface, a water film is formed due to frictional heat between the ice-snow road surface and the tire, and this water film reduces the coefficient of friction between the tire and the ice-snow road surface. , It is said that it is a cause of deterioration of performance on ice. In this regard, since the rubber member according to the embodiment of the present invention has a plurality of minute recesses on the surface, the minute recesses function as drainage grooves to remove the water film and between the tire and the ice / snow road surface. It is possible to suppress a decrease in the friction coefficient. Further, in the rubber member of one embodiment of the present invention, not only the micro-recess is present on the surface, but also the water thickening substance is arranged on the inner surface of the micro-recess. Therefore, the surface roughness of the rubber member is substantially increased, and the water thickening substance is apparently dispersed in the water that has infiltrated into the minute recesses, and the viscosity of the water is increased, so that the friction coefficient (static friction coefficient) is increased. And the decrease in the coefficient of dynamic friction) is further suppressed, so that the performance on ice of the tire can be significantly improved. Further, in addition to the above-mentioned effects, the rubber member of the present invention (1) has an extremely hydrophobic rubber component, so that more water can be infiltrated into the minute recesses where the water thickening substance is present. , (2) The water thickening substance cuts through the water film and further enhances the function as a drainage groove of the minute recess, (3) The effect of scratching the water thickening substance that can come into contact with the ice and snow road surface, etc. It is thought that it can be done.

Here, in the present invention, as shown in FIG. 1, the "micro recess" is a recess existing on the surface of the rubber member, has a maximum depth (D _max ) of 1 to 500 μm, and is a rubber member. _{The longest diameter (L max} ) in the unfolded view of the surface of the surface is in the range of 1 to 500 μm. Therefore, the "micro recess" includes those having various outer shapes. The presence or absence of this "micro recess" can be confirmed, for example, from a photograph of the surface of the rubber member taken with an electron microscope.

Further, in the present invention, the embodiment in which the water thickening substance is "arranged" on the inner surface of the minute recesses or the like includes the embodiment in which the water thickening substance is firmly adhered to the inner surface of the minute recesses or the like. Both aspects that are not included are included. However, it is preferable that the water thickening substance is not firmly adhered to the inner surface such as a minute recess.

In FIG. 1, the water thickening substance 3 is arranged on the inner surface of all the micro-concave parts 2 shown in the drawing. However, in the rubber member of one embodiment of the present invention, the water thickening substance is used on the road surface. It may be arranged on the inner surface of at least one minute recess existing on the surface (hereinafter, may be referred to as “grounding target surface”) that can come into contact with external factors such as. However, from the viewpoint of sufficiently obtaining the desired action and effect, it is preferable that the water thickening substance is arranged on the inner surface of more, preferably all the minute recesses, which are present on the surface to be grounded.

The number of minute recesses on the surface of the rubber member according to the embodiment of the present invention is not particularly limited and can be appropriately determined depending on the intended purpose. From the viewpoint of improving the number of pieces / mm ² , it is preferably 70 to 200 pieces / mm 2, and more preferably 130 to 150 pieces / mm ² .
As for the number of the micro-recesses, 10 square regions having a side of 1 mm are arbitrarily selected from the photograph of the surface of the rubber member taken by an electron microscope, and the number of the micro-recesses observed in each region is counted. , Can be obtained as the average value.

Further, in the rubber member of one embodiment of the present invention, not only a plurality of micro-recesses 2 are present on the surface as in the tread portion 1 of the example shown in FIG. 2, but also a plurality of micro-cavities 4 are provided therein. Existence, and in addition to the water thickening substance 3a being arranged on the inner surface of the micro-concave portion 2, the water thickening substance 3b is also arranged on the inner surface of the plurality of microcavities 4. Is preferable. Since the rubber member of one embodiment of the present invention has such an aspect, even if the surface is worn by many years of use and the micro-concave portion 2 disappears with it, the micro-cavity portion 4 existing inside the micro-cavity portion 4 is present at any time. Appears on the surface as new micro-recesses, and the water-thickening substance arranged on the new micro-recesses and the inner surface thereof functions as a drainage groove and substantially increases the surface roughness of the rubber member. Alternatively, the viscosity of the infiltrated water is increased to suppress a decrease in the friction coefficient. Therefore, the rubber member of the embodiment of the present invention having the above aspect can bring high performance on ice to a tire or the like for a long period of time.
The rubber member according to the embodiment of the present invention may have a mode in which the minute recess and the minute cavity are connected.

Here, the size of the microcavity is not particularly limited, but the length of the longest straight line connecting any two points on the inner surface is preferably 1 μm to 10 mm.

Then, as described above, in the rubber member of the embodiment of the present invention in which the water thickening substance is also arranged on the inner surface of the microcavities, the water thickening substance is contained on the inner surface of the microrecesses 2 and the microcavities. It may be present in a place other than the inner surface of the part 4, for example, in the non-cavity part 5. However, from the viewpoint of efficiently improving the performance on ice of tires and the like without the need to use an excessive amount of the water thickening substance, the proportion of the water thickening substance present in the non-cavity portion 5 is preferably smaller. Such a rubber member is preferably used, for example, by using a rubber composition in which a foaming agent and a water-thickening substance-containing organic fiber containing a water-thickening substance and a resin are mixed with a rubber component. Can be manufactured. In the rubber member produced by using the above rubber composition, the proportion of the water thickening substance present in the non-cavity portion is almost 0.
Regarding this point, it is necessary to discuss a suitable mode of the rubber member by specifying "the ratio of the water thickening substance present in the non-cavity portion to the total amount of the water thickening substance contained in the rubber member". It is also possible that there is. However, it takes a remarkably excessive time to determine the total amount of the water thickening substance contained in the rubber member, which is not practical. Based on the above, it is clear that it is technically impossible to directly specify "the ratio of the water thickening substance present in the non-cavity portion to the total amount of the water thickening substance contained in the rubber member". be.

Further, in the rubber member of one embodiment of the present invention, it is also preferable that a particularly large amount of the water thickening substance is arranged on the inner surface of the minute recess 2. A rubber member in which a large amount of water thickening substance is arranged on the inner surface of the minute recesses can significantly improve the performance on ice, especially in the initial stage of use of a tire or the like. In addition, a large amount of water thickening substance is arranged on the inner surface of the minute recess (increase the ratio of the water thickening substance arranged on the inner surface of the minute recess in the total amount of the water thickening substance contained in the rubber member). Examples of the method include coating, spraying or impregnating a water thickening substance. This coating, spraying, or impregnation can be performed at any time after the rubber composition is vulcanized to prepare a vulcanized rubber having microrecesses, and the rubber composition is arranged on the inner surface of the microrecesses. Since the amount of the water thickening substance can be easily controlled, the rubber member of the present invention can be easily manufactured.
Regarding this point, by specifying "the ratio of the water thickening substance arranged on the inner surface of the minute recesses to the total amount of the water thickening substance contained in the rubber member", a suitable mode of the rubber member It may be necessary to discuss. However, it takes a remarkably excessive time to determine the total amount of the water thickening substance contained in the rubber member, which is not practical. Based on the above, it is technically impossible to directly specify "the ratio of the water thickening substance arranged on the inner surface of the minute recesses to the total amount of the water thickening substance contained in the rubber member". It is clear that.

Further, the rubber member according to the embodiment of the present invention needs to have a certain amount or more of the water thickening substance arranged on the inner surface of each of the minute recesses 2. More specifically, the average coverage of the water thickening substance on the inner surface of the minute recesses existing on the surface of the rubber member needs to be 10% or more, preferably 20% or more, preferably 25%. The above is more preferable, 30% or more is further preferable, and 75% or more is particularly preferable. If the average coverage is less than 10%, the performance on ice of tires and the like cannot be effectively improved.
From the same viewpoint, the average coverage of the inner surface of the minute recesses existing on the surface of the rubber member to be grounded is preferably 10% or more, preferably 20% or more, and preferably 25% or more. More preferably, it is more preferably 30% or more, and particularly preferably 75% or more.
In the present specification, the "average coverage of the water-thickening substance on the inner surface of the micro-recess" is the area covered by the water-thickening substance in the area of the micro-recess in the developed view of the surface of the rubber member. It shall refer to the average value of the ratio of the total of. Further, the "average coverage of the water thickening substance on the inner surface of the minute recesses" is found to be minute from, for example, a photograph of the surface of the rubber member (preferably subjected to binarization treatment) taken with an electron microscope. Ten recesses can be arbitrarily selected, and the ratio of the total area covered by the water thickening substance to the total area of each of the minute recesses can be calculated and obtained.

Here, in the rubber member of one embodiment of the present invention, a substance that does not satisfy the definition of the water thickening substance described above may be arranged on the inner surface of the minute recess. However, from the viewpoint of effectively improving the performance on ice, it is preferable that the rubber member according to the embodiment of the present invention does not have a substance that does not satisfy the definition of the water thickening substance arranged on the inner surface of the minute recess.

-Water thickener-
As described above, the water thickening substance used in the present invention is 25 ° C. of the aqueous dispersion measured by a cone plate type viscometer when the aqueous dispersion is prepared so that its concentration is 23% by mass. A substance having a viscosity of 20 Pa · s or more at an arbitrary shear rate of 0.01 / s to 0.1 / s. By arranging the water thickening substance on the inner surface of the minute recesses of the rubber member, the surface roughness of the rubber member is substantially increased, and the viscosity of the infiltrated water is increased to suppress a decrease in the friction coefficient. It is thought that it can be done. Here, the viscosity of the water thickening substance is preferably 500 Pa · s or more, more preferably 1000 Pa · s or more, and more preferably 5000 Pa · s or more, from the viewpoint of further suppressing the decrease in the friction coefficient. It is more preferable to have a coefficient of 8000 Pa · s or more, and it is particularly preferable to have a coefficient of 8000 Pa · s or more. On the other hand, the viscosity of the water thickening substance is not particularly limited and is preferably 50,000 Pa · s or less.
The viscosity can be measured by the cone plate type viscometer described above using, for example, a cone having a diameter of 60 mm and an angle of 0.99 °.

The shape of the water thickening substance is not particularly limited as long as the viscosity of the aqueous dispersion is 20 Pa · s or more, and can be appropriately selected depending on the intended purpose. For example, particulate or fibrous. , Layered, tetrapod, etc. Here, it is important to select an appropriate shape of the water thickening substance according to the size of the minute recesses in consideration of the amount and size thereof.
Alternatively, the water thickening substance may be in the form of a gel.

The major axis of the water thickening substance is not particularly limited as long as the viscosity of the aqueous dispersion is 20 Pa · s or more, and can be appropriately selected depending on the intended purpose, but is 50 μm or less. It is preferably 1.0 μm or less, and particularly preferably less than 100 nm. When the major axis of the water thickening substance is 50 μm or less, the surface roughness of the rubber can be sufficiently increased when it is arranged in the minute recesses of the rubber member, and the performance on ice of the tire can be effectively improved. .. On the other hand, the major axis of the water thickening substance is preferably 1.0 nm or more from the viewpoint of effective improvement of on-ice performance and ease of procurement.
Here, in the present specification, the "major axis" of the water thickening substance shall refer to the length of the longest straight line connecting any two points on the outer surface of the water thickening substance. The "major axis" of the water thickening substance can be determined, for example, by photographing the water thickening substance with an electron microscope.

The water thickening substance used in the present invention may be an organic substance or an inorganic substance.
The inorganic substance is not particularly limited and may be appropriately selected depending on the intended purpose. For example, diamond, silica, glass, gypsum, granite, fluorite, regular length stone, aluminum hydroxide, alumina, silver, iron, etc. Examples thereof include inorganic substances such as titanium dioxide, cerium oxide, zinc oxide, carbon black, single-walled carbon nanotubes, multi-walled carbon nanotubes, and clay. These may be used alone or in combination of two or more.
Here, the above-mentioned inorganic substance such as diamond may have its surface modified with an arbitrary functional group (for example, a hydroxyl group, a carboxyl group, an amino group, etc.).

The organic substance is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include cellulose, aramid, nylon and polymethyl methacrylate. Further, as the organic substance, from the viewpoint of increasing the viscosity of water, an organic substance commonly used as a polymer gel such as a water-retaining material or a water-absorbing polymer can be mentioned. These may be used alone or in combination of two or more.

The water thickening substance preferably has a hydroxyl group. When the water thickening substance has a hydroxyl group, the viscosity of the water that has penetrated into the minute recess can be further increased due to the unique interaction between the hydroxyl groups, and the performance of the rubber article on ice can be further improved. Here, examples of the water thickening substance having a hydroxyl group include cellulose, an arbitrary inorganic substance modified with a hydroxyl group, and the like.

Further, the water thickening substance is preferably insoluble in water (for example, water at 25 ° C.) from the viewpoint of more reliably obtaining the effect of removing the water film formed between the ice-snow road surface and the tire. ..

-Rubber component-
The rubber component is not particularly limited and may be appropriately selected depending on the intended purpose. For example, only natural rubber (NR) may be used, or only diene-based synthetic rubber may be used. Diene-based synthetic rubber may be used in combination. The diene synthetic rubber is not particularly limited and may be appropriately selected depending on the intended purpose. For example, butadiene rubber (BR), styrene-butadiene rubber (SBR), isoprene rubber (IR), chloroprene rubber ( CR), ethylene-propylene-diene rubber (EPDM), acrylonitrile-butadiene rubber (NBR), butyl rubber (IIR) and the like. These may be used alone or in combination of two or more.

(Manufacturing method of rubber member)
As described above, the rubber member according to the embodiment of the present invention can be produced by using a rubber composition containing a rubber component and any other component. Further, in manufacturing the rubber member according to the embodiment of the present invention, at least a plurality of minute recesses are formed on the surface of the rubber member, and a water thickening substance is arranged on the inner surface of the minute recesses. ,is required. The method for achieving these is not particularly limited, and can be appropriately selected depending on the purpose. Here, the method for producing a rubber member according to the present invention includes at least a step of applying a water thickening substance to the minute recesses formed on the surface of the vulcanized rubber. Then, according to the method for manufacturing a rubber member according to the present invention, the rubber member of the present invention described above can be manufactured. Hereinafter, a method for manufacturing a rubber member according to an embodiment of the present invention including such a step will be described in detail.

The method for producing a rubber member according to an embodiment of the present invention is, for example, a step of preparing a rubber composition by blending at least a foaming agent with a rubber component (rubber composition preparation step A) and a step of preparing the prepared rubber composition. A step of scraping off the outer surface of the vulcanized rubber obtained by vulcanization (vulcanization A step) and a step of applying a water thickening substance to minute recesses on the surface of the vulcanized rubber (water thickening substance applying step). And include.

-Rubber composition preparation step A-
The rubber composition preparation step A is a step of blending a foaming agent and an arbitrary other component with the rubber component and kneading them to obtain a rubber composition. Specific examples of the rubber component are the same as those described above. By blending the foaming agent, a plurality of minute recesses can be easily formed on the surface of the rubber member, and a plurality of minute cavities can be formed inside the rubber member.

Examples of the foaming agent include dinitrosopentamethylenetetramine (DPT), azodicarboxylicamide (ADCA), dinitrosopentastyrenetetramine, benzenesulfonylhydrazide derivative, p, p'-oxybisbenzenesulfonylhydrazide (OBSH), ammonium bicarbonate. , Sodium bicarbonate, ammonium carbonate, nitrososulfonylazo compound, N, N'-dimethyl-N, N'-dinitrosophthalamide, toluenesulfonyl hydrazide, p-toluenesulfonyl semicarbazide, p, p'-oxybisbenzenesulfonyl semicarbazide And so on. Among these, azodicarbonamide (ADCA) and dinitrosopentamethylenetetramine (DPT) are preferable from the viewpoint of processability. These foaming agents may be used alone or in combination of two or more. The blending amount of the foaming agent is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably in the range of 1 to 10 parts by mass with respect to 100 parts by mass of the rubber component.

Further, in the rubber composition preparation A step, it is preferable to use a foaming aid in combination with the foaming agent. Examples of the foaming aid include urea, stearic acid, zinc stearate, zinc benzenesulfinate, zinc white and the like. These may be used alone or in combination of two or more. By using a foaming aid in combination with a foaming agent, it is possible to promote the foaming reaction, increase the degree of completion of the reaction, and suppress unnecessary deterioration over time.

Further, in the rubber composition preparation step A, in addition to the above-mentioned rubber component, any other component, for example, a vulcanizing agent such as sulfur, a vulcanization aid such as stearic acid, dibenzothiazyl disulfide or N-cyclohexyl-2. -Vulcanization accelerators such as benzothiazolysulfenamide, vulcanization accelerators such as zinc flower, anti-aging agents, colorants, antistatic agents, dispersants, lubricants, antioxidants, softeners, carbon black and A filler such as silica can be blended. These may be used alone or in combination of two or more.
Then, the rubber composition can be prepared by kneading the above-mentioned components according to a conventional method.

-Vulcanization A process-
The vulcanization A step is a step of vulcanizing the rubber composition prepared in the rubber composition preparation A step to obtain a vulcanized rubber and scraping off the outer surface of the vulcanized rubber. In this vulcanization A step, the blended foaming agent foams to generate gas, and due to this gas, a plurality of microcavities are formed inside the vulcanized rubber and a plurality of microrecesses are formed on the surface. Further, by scraping off the outer surface of the vulcanized rubber, it is possible to more effectively obtain a surface on which a plurality of micro-recesses derived from the above-mentioned micro-cavities are formed. The method of scraping off the outer surface of the vulcanized rubber is not particularly limited.
The vulcanization method is not particularly limited and can be appropriately selected depending on the type of rubber component and the like. However, when the obtained rubber member is used for the tread portion of the tire, it is preferable to perform mold vulcanization. The vulcanization temperature is not particularly limited and can be appropriately selected depending on the vulcanization time and the like, but is preferably 100 to 200 ° C. from the viewpoint of obtaining desired rubber physical characteristics and foaming rate. The vulcanization time is not particularly limited and can be appropriately selected depending on the vulcanization temperature and the like, but is preferably 3 to 25 minutes from the viewpoint of obtaining desired rubber physical characteristics and foaming rate.

The foaming ratio (Vs) of the vulcanized rubber is preferably 3 to 40%, more preferably 5 to 35%. When the foaming rate is 3% or more, it is possible to suppress that the volumes of the minute recesses and the minute cavities that can remove water on the ice and snow road surface become too small and the drainage performance deteriorates. When it is 40% or less, it is possible to prevent the number of minute recesses and minute cavities from becoming too large and the durability of the tire from being lowered.
The foaming rate (Vs) (%) is calculated by the following formula (I):
_{Vs = (ρ o / ρ 1} -1) × 100 ··· (I)
[In the formula, ρ ₁ is the density of the vulcanized rubber (g / cm ³ ), and ρ ₀ is the density of the solid phase portion of the vulcanized rubber (g / cm ³ )].

-Water thickening substance application process-
In the water thickening substance applying step, the water thickening substance is (subsequently) applied to the minute recesses formed on the surface of the vulcanized rubber obtained in the vulcanization A step to obtain the rubber member of the present invention. It is a process. Specific examples of the water thickening substance are the same as those described above.
The method of applying the water-thickening substance is not particularly limited, and can be appropriately selected depending on the type of the water-thickening substance to be used and the like. Examples of the above method include a method of manually applying a water thickening substance (coating method), a method of spraying a water thickening substance together with a gas using an instrument such as an airbrush (spray method), and water in a dispersion medium. Examples thereof include a method of impregnating a vulture rubber with a liquid obtained by dispersing a thickening substance and then drying (impregnation method). In each of these methods, the water thickening substance can be easily arranged on the inner surface of the micro-concave as compared with the case where the water-thickening substance is arranged by blending, and the water-thickening substance can be easily arranged on the inner surface of the micro-concave. It is preferable in that the amount of the water-thickening substance arranged (the average coverage of the water-thickening substance on the inner surface of the minute recesses) can be controlled.

Examples of the instruments that can be used in the spraying method include an AIRTEX airbrush "Meteor" and a Tamiya airbrush "74541". Examples of the gas that can be used in the spraying method include air, nitrogen, oxygen, propane, and the like. Among these, propane is preferable from the viewpoint of obtaining good adhesion.
The dispersion medium that can be used in the impregnation method is not particularly limited as long as it can be removed by drying, and examples thereof include water, methanol, ethanol, isopropanol, etc. Among these, high drying rate and safety. Ethanol and isopropanol are preferable from the viewpoint of ensuring the above. Further, in the impregnation method, the concentration of the water thickening substance in the liquid is not particularly limited and can be appropriately selected according to a desired average coverage or the like, but for example, 0.01 to 1.0 mass. It is preferably%. Further, the drying temperature in the impregnation method is not particularly limited and may be appropriately selected depending on the boiling point of the dispersion medium to be used and the like, but is preferably 10 to 200 ° C. for example. Furthermore, the drying time in the impregnation method is not particularly limited and may be appropriately selected depending on the concentration of the water thickening substance in the liquid and the like, but is preferably 10 to 360 minutes, for example.

In any of the coating method, the spraying method, and the impregnation method, the water thickening substance can be arranged on the surface other than the minute recesses of the obtained rubber member, but this water thickening substance may be removed. You don't have to.

Further, as a method for manufacturing a rubber member according to another embodiment of the present invention, the above-mentioned "method for manufacturing a rubber member according to one embodiment of the present invention" and the "method for manufacturing another rubber member" described later are used. Examples thereof include a combined method, specifically, a method including a fiber preparation step, a rubber composition preparation B step and a vulcanization B step, which will be described later, and a water thickening substance applying step described above.

In addition to the above manufacturing method, the rubber member of the present invention includes, for example, a step of preparing an organic fiber containing a water thickening substance (fiber preparation step), and a rubber component containing at least a foaming agent and the water thickening substance. A step of blending organic fibers to prepare a rubber composition (step of rubber composition preparation B) and a step of vulcanizing the prepared rubber composition and scraping off the outer surface of the obtained vulcanized rubber (vulcanization B). It can also be manufactured by a method including (step) (sometimes referred to as "a method for manufacturing another rubber member"). According to this method, the water thickening substance can be arranged on the inner surface of the minute recesses by blending.

-Fiber preparation process-
The fiber preparation step is a step of preparing a water-thickening substance-containing organic fiber, and the water-thickening substance-containing organic fiber is for arranging the water-thickening substance on the inner surface of the minute recesses and the minute cavities of the rubber member. It is compounded in. Here, the water-thickening substance-containing organic fiber usually contains a resin and a water-thickening substance. Specific examples of the water thickening substance are the same as those described above.

It is preferable that the melting point or softening point of the resin is lower than the maximum temperature reached by the rubber composition at the time of vulcanization of the rubber composition, that is, the maximum vulcanization temperature. When the water-thickening substance-containing organic fiber is blended in the rubber composition containing the foaming agent, the resin constituting the water-thickening substance-containing organic fiber is melted or softened during vulcanization, while the rubber matrix. Among them, the gas generated from the foaming agent during vulcanization tends to stay inside the melted or softened resin constituting the fiber, as compared with the rubber matrix in which the vulcanization reaction has proceeded. Here, if the melting point or softening point of the resin is lower than the maximum vulcanization temperature, the resin is rapidly melted or softened during vulcanization of the rubber composition, and microcavities can be efficiently formed.

Specific examples of such resins include crystalline polymer resins such as polyethylene (PE), polypropylene (PP), polybutylene, polybutylene succinate, polyethylene succinate, and syndiotactic-1,2-polybutadiene (SPB). ), Polyvinyl alcohol (PVA), polyvinyl chloride (PVC) and other single-composition polymers, and those in which their melting points are controlled within an appropriate range by copolymerization, blending and the like. These crystalline polymer resins may be used alone or in combination of two or more. Among these crystalline polymers, polyethylene (PE) and polypropylene (PP) are preferable from the viewpoint of versatility and availability, and polyethylene (PE) is more preferable from the viewpoint of having a relatively low melting point and easy handling. .. On the other hand, a resin having a hydroxyl group, for example, polyvinyl alcohol, is more preferable from the viewpoint of attracting more water, which is the target of increasing the viscosity of the water thickening substance, into the minute recesses.

The melting point or softening point of the resin is preferably 10 ° C. or higher, more preferably 20 ° C. or higher, lower than the maximum vulcanization temperature of the rubber composition. The industrial vulcanization temperature of a rubber composition is generally about 190 ° C. at the maximum, but for example, when the maximum vulcanization temperature is set to 190 ° C., the melting point or softening point of the resin is set. The temperature is usually selected in the range of 190 ° C. or lower, preferably 180 ° C. or lower, and more preferably 170 ° C. or lower.

Here, the water-thickening substance-containing organic fiber preferably contains 0.5 to 200 parts by mass of the water-thickening substance with respect to 100 parts by mass of the resin. When the content of the water thickening substance is 0.5 parts by mass or more, the obtained rubber member can significantly improve the performance on ice of a tire or the like, while when it is 200 parts by mass or less, High spinning operability can be maintained.

Further, the water thickening substance-containing organic fiber preferably has an average diameter of 10 to 100 μm. When the average diameter is 10 μm or more, it is possible to spin from the resin and the water thickening substance more reliably, and when it is 100 μm or less, the water thickening substance-containing organic fiber is blended in the rubber composition. It is possible to prevent the number of copies from becoming too high.

Further, the water thickening substance-containing organic fiber preferably has an average length of 0.5 to 20 mm, more preferably 1 to 10 mm. When the average length is 0.5 mm or more, micro-recesses and micro-cavities can be formed more easily, and when the average length is 20 mm or less, the hardness of the fibers does not become too high and the fibers are sufficiently kneaded. can do.

The method for preparing the water thickening substance-containing organic fiber is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a melt spinning method, a gel spinning method, and a solution spinning method. For example, in the melt spinning method, after heating and melting the raw material resin in an extruder, the water thickening substance is dispersed, and then the bundle of fibers extruded from the spinning nozzle is stretched in the spinning cylinder and cooled by an air flow. Then, an oil agent is added to the fibers, and the fibers are combined into one and wound to prepare a water-thickening substance-containing organic fiber. Further, in the solution spinning method, a water thickening substance is dispersed in a polymer solution in which a raw material resin is dissolved, and the water thickening substance is extruded from a spinning nozzle to be fiberized by desolving or the like to obtain a water thickening substance-containing organic fiber. Can be manufactured.

-Rubber composition preparation step B-
In the rubber composition preparation B step, a foaming agent, a water thickening substance-containing organic fiber prepared in the fiber preparation step, and any other component are mixed with the rubber component and kneaded to obtain a rubber composition. It is a process. The specific content of the rubber composition preparation B step is the same as that of the rubber composition preparation A step described above, except for the following contents.

The blending amount of the water thickening substance-containing organic fiber in the rubber composition preparation B step is not particularly limited and can be appropriately determined depending on the intended purpose, but is 0.5 to 0.5 to 100 parts by mass of the rubber component. It is preferably 30 parts by mass. When the blending amount of the water thickening substance-containing organic fiber is 0.5 parts by mass or more, the volume ratio of the minute recesses and the minute cavities in the vulcanized rubber is increased, and a sufficient amount of the water thickening substance is added. By arranging the tire in the minute recesses and the minute cavities, the performance on ice of the tire can be effectively improved, and when the amount is 30 parts by mass or less, the water thickening substance-containing organic fiber in the rubber composition can be used. It is possible to suppress deterioration of dispersibility and processability of the rubber composition.

-Vulcanization B process-
The vulcanization B step is a step of vulcanizing the rubber composition prepared in the rubber composition preparation B step to obtain a vulcanized rubber, and scraping off the outer surface of the vulcanized rubber to obtain a rubber member of the present invention. be. In this vulcanization B step, the resin constituting the water-thickening substance-containing organic fiber is melted by the vulcanization, and the blended foaming agent is foamed to generate gas. Then, a film is formed so that the molten resin and the water thickening substance surround the gas, and a plurality of microcavities are formed inside the vulcanized rubber and a plurality of microrecesses are formed on the surface. In addition to this, due to the action of gas inflow from the foaming agent, the total amount of the water thickening substance constituting the water thickening substance-containing organic fiber is formed on the inner surface of the film, specifically by the molten resin. It is known to move onto the constituent planes and thus be placed (attached) to the inner surface of the microcavities. Then, by scraping off the outer surface of the vulcanized rubber, it is possible to more effectively obtain a surface on which a plurality of micro-recesses derived from the above-mentioned micro-cavities are formed. The method of scraping off the outer surface of the vulcanized rubber is not particularly limited.
Here, the specific content of the vulcanization B step is the same as that of the vulcanization A step described above.

(tire)
The tire of the present invention is characterized in that the above-mentioned rubber member is provided in the tread portion. According to such a tire, since the above-mentioned rubber member is used at least for the tread portion, the performance on ice is improved. Therefore, the tire of the present invention is preferably used as a studless tire, particularly as a studless tire for passenger cars. The tire of the present invention is not particularly limited except that the above-mentioned rubber member is used for the tread portion, and can be manufactured according to a conventional method.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples, and can be appropriately modified without changing the gist thereof.

(Examples 1 to 10, Comparative Examples 1 to 7)
A rubber composition was prepared according to a conventional method using the formulation shown in Table 1. A tread portion (unvulcanized) of a tire was prepared using this rubber composition and arranged in an appropriate place to prepare a raw tire. This raw tire was mold vulcanized at 165 ° C. for 20 minutes to obtain a vulcanized tire.
Table 4 described later shows the formulation selected in each example.

* 1 JSR Corporation, "BR01", cis-1,4-polybutadiene * 2 Asahi Carbon Co., Ltd., "Carbon N220", agglomerate is 100 nm or more * 3 Nippon Silica Industry Co., Ltd., "Nipsil-VN3" , Agromelate is 100 nm or more * 4 "Nocrack 6C" manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
* 5 Dibenzothiazyl disulfide * 6 N-cyclohexyl-2-benzothiazolyl sulfeneamide * 7 Dinitrosopentamethylenetetramine * 8 Urea

Next, a passenger car equipped with the above-mentioned vulcanized tire was run for 50 km or more to acclimatize the surface, and the outer surface of the tire was uniformly scraped off by a predetermined thickness. Then, in the examples other than Comparative Examples 1 and 2, the minute substances shown in Table 2 below were prepared, and the minute substances were vulcanized in the above-mentioned tire tread by any of the methods shown in Table 3 below. It was applied to the inner surface of substantially all the minute recesses on the surface to be grounded. In this way, a radial tire for a passenger car having a size of 185 / 70R13 having a rubber member in the tread portion was manufactured.
In addition, Table 4 described later shows the minute substances selected in each example and the method of imparting them.

* 10 "Udiamond molt" manufactured by Air Brown Co., Ltd.
* 11 Degssa, wet silica, VN3 grade * 12 Degssa, wet silica, VN2 grade * 13 Potters Barotini Co., Ltd., "EMB10"
* 14 "Unibeads" manufactured by Unitika Ltd.
* 15 Solubility in water at 25 ° C * 16 Cone plate type viscometer (cone diameter 60 mm, angle 0.99 °) of an aqueous dispersion prepared so that the concentration of the target substance is 23% by mass. Viscosity at 25 ° C. and shear rate 0.02 / s as measured by

For the obtained tire, the foaming rate (Vs) (%) of the vulcanized rubber forming the tread portion was calculated by the following formula (I). The results are shown in Table 4.
_{Vs = (ρ 0 / ρ 1} -1) × 100 ··· (I)
[In the formula, ρ ₁ is the density of the vulcanized rubber (g / cm ³ ), and ρ ₀ is the density of the solid phase portion of the vulcanized rubber (g / cm ³ ). ]

Further, with respect to the obtained tire, the surface morphology and internal morphology of the tread portion as a rubber member and the performance on ice of the tire were evaluated by the following methods.

<Surface and internal morphology of the tread>
A rubber piece including the surface to be grounded was cut out from the tread center portion of the obtained tire, and the surface and cut surface of this sample were observed with a scanning electron microscope (SEM). Then, the presence or absence of micro-recesses on the surface of the tread to be grounded and the presence or absence of micro-cavities inside the tread were confirmed.
Further, 10 minute recesses are arbitrarily selected from the photograph of the surface of the tread to be grounded taken by SEM, and the ratio of the total area covered by the minute substance to the total area of each minute recess is calculated. The average coverage (%) of the minute substance on the inner surface of the minute recess was calculated. These results are shown in Table 4.

Here, for reference, a schematic diagram of an image of the surface of the sample in Example 1 by SEM is shown in FIG. 3, and a schematic diagram of an image observed by SEM on the surface of the sample in Comparative Example 2 is shown in FIG. .. From these figures, the average coverage of the nanomaterial on the inner surface of the micro-recess can be found by performing the binarization treatment.

<Tire performance on ice>
A passenger car equipped with the obtained tires is driven on a general asphalt road for 200 km, then on a flat road on ice, and when the speed is 20 km / h, the brakes are applied to lock the tires until the vehicle is stopped. The braking distance was measured. The reciprocal of the braking distance of the tire of Comparative Example 1 was set as 100 and displayed as an index. The larger the index value, the better the performance on ice. The results are shown in Table 4.

(Examples 11 to 18, Comparative Examples 8 and 9)
First, the resin shown in Table 5 and the minute substance shown in Table 2 described above were prepared.

* 17 "HY 442" manufactured by Japan Polyethylene Corporation
* 18 "Kuraron K-11" manufactured by Kuraray Co., Ltd.
* 19 Value measured for durometer D hardness in accordance with JIS K 7215.

Using the resin and the fine substance prepared as described above, fibers (fine substance-containing fibers) were prepared according to a usual melt spinning method using the formulation shown in Table 6. In addition, 20 locations were randomly selected for each of the prepared fibers, the diameter and length were measured using an optical microscope, and the average value was calculated. As a result, the average diameter of each fiber was 30 μm, and the average length was obtained. The diameter was 2 mm.
Table 8 described later shows the fibers selected in each example.

Using the fibers prepared as described above, kneading was carried out according to a conventional method using the compounding formula shown in Table 7 to prepare a rubber composition in which the compounded fibers were arranged in a certain direction. Next, a tread portion (unvulcanized) of the tire was prepared using this rubber composition and arranged in an appropriate place to prepare a raw tire. This raw tire was mold vulcanized at 165 ° C. for 10 minutes to obtain a vulcanized tire. The maximum vulcanization temperature at the time of vulcanization of each rubber composition was 165 ° C.

* 20 Selected from the fibers listed in Table 6.

Next, a passenger car equipped with the above-mentioned vulcanized tire was run for 50 km to acclimatize the surface, and the outer surface of the tire was uniformly scraped off by a predetermined thickness. In this way, a radial tire for a passenger car having a size of 185 / 70R13 having a rubber member in the tread portion was manufactured.

For the obtained tire, the foaming rate (Vs) (%) of the vulcanized rubber forming the tread portion was calculated by the same method as above, and the presence or absence of minute recesses on the surface of the tread portion to be grounded and the inside of the tread portion were calculated. The presence or absence of the microcavities in the tire tread and the average coverage (%) of the micromaterials on the inner surface of the microrecesses were determined, and the performance on ice of the tire was further evaluated.
These results are shown in Table 8.

From Tables 4 and 8, the rubber member of the example in which a plurality of micro-recesses are present, a water thickening substance is arranged on the inner surface of the micro-recesses, and the average coverage is 10% or more is For example, it can be seen at least that the performance of a tire as a rubber article on ice can be improved.

According to the present invention, it is possible to provide a rubber member capable of improving the performance of a rubber article on ice when used for a rubber article such as a tire. Further, according to the present invention, it is possible to provide a method for manufacturing a rubber member, which can obtain a rubber member capable of improving the performance of a rubber article such as a tire on ice. Further, according to the present invention, it is possible to provide a tire having improved performance on ice.

1 Tread part 2 Micro-concave part 3 Water-thickening substance 3a Water-thickening substance arranged on the inner surface of the micro-concave part 3b Water-thickening substance arranged on the inner surface of the micro-cavity part 4 Micro-cavity part 5 Non-cavity part

Claims (6)

A rubber member having a water thickening substance
There are a plurality of minute recesses on the surface of the rubber member,
The water thickening substance is arranged on the inner surface of the micro-recess, and
The average coverage of the water thickening substance on the inner surface of the micro-recess is 10% or more.
Here, the water thickening substance was measured by a cone plate type viscometer using a cone having a diameter of 60 mm and an angle of 0.99 ° when the aqueous dispersion was prepared so that its concentration was 23% by mass. The aqueous dispersion is defined as a substance having a viscosity of 20 Pa · s or more at a shear rate of 0.02 / s at 25 ° C.
The viscosity of the aqueous thickening agent wherein the rubber member has the state, and are more 6000 Pa · s,
The water thickening substance is diamond or silica, and is a rubber member having a major axis of 60 nm or less. The rubber member according to claim 1.
Further, there are a plurality of microcavities inside, and the water thickening substance is also arranged on the inner surface of the microcavities.
A rubber member produced by using a rubber composition obtained by blending a foaming agent and a water-thickening substance-containing organic fiber containing a water-thickening substance and a resin with respect to a rubber component. The rubber member according to claim 1 or 2 , wherein the water thickening substance has a hydroxyl group. The rubber member according to any one of claims 1 to 3 , wherein the water thickening substance is arranged on the inner surface of the micro-concave by coating, spraying or impregnating. The method for manufacturing a rubber member according to any one of claims 1 to 4.
A method for producing a rubber member, which comprises a step of applying the water thickening substance to the minute recesses formed on the surface of the vulcanized rubber. A tire comprising the rubber member according to any one of claims 1 to 4 in a tread portion.

Images