KR20190088962A - Conductive hydrophilic tire composition - Google Patents

Abstract

The present invention provides a conductive hydrophilic tire composition comprising: at least one of polar rubbers selected from a carboxylated-acrylonitrile-butadiene rubber (XNBR), a fluoro elastomer (FKM), and epichlorohydrin polyethyleneoxide allyl glycidyl ether (GECO); a specific water-expandable material. Therefore, an electric leakage sensor can detect a leaking source by easily passing a current generated from underground defect.

Description

[0001] CONDUCTIVE HYDROPHILIC TIRE COMPOSITION [0002]

TECHNICAL FIELD The present invention relates to a tire composition, and more particularly, to a conductive hydrophilic tire composition.

Leaks from underground cables can threaten the environment if not diagnosed and repaired. In particular, short-circuiting can lead to sudden human / animal electric shocks leading to death and can completely damage the buried electrical system (Norell et al., Trans. ASAE, 26 (1983), 1506-1511, Appleman et al., Journal of Dairy Science, 68 (1985), pp. 1554-1567 and USDA Handbook, p. 696). The cause of the short circuit is a short circuit due to damage to the cable itself, a short circuit due to damage due to aging of the tree roots or the cable line, a short circuit due to poor construction, and most short circuits occur in the underground buried section. There is always a risk of damages due to tensile stress on the ground subsidence and damage due to excavation work which is occasionally occurring, and there is a risk of safety accidents and indirect accidents due to occurrence of electric leakage in a certain section.

However, in general, it is not preferable to expose on the ground. In case of cable cable installed underground, it is not possible to accurately detect the short circuit location due to lack of invisibility and suitable usable equipment. It has been repaired by work. As an example, it is difficult to detect a short circuit by using a megeter when the leakage current of a buried underground wire for a street lamp is detected, and then it is necessary to start from one end of the leak current cable with the related tester equipment and to probe the current line to the end of the cable. , Which has caused problems of material and time loss due to uneconomical and unreasonable work because the wires which are not damaged are replaced.

In order to solve this problem, various methods for detecting the leakage point efficiently have been introduced, but they have not been effective and effective. For example, the infrared detection method presented in the SDA Handbook, page 696, published by the US Department of Agriculture, requires a considerable amount of expertise to perform temperature log analysis by applying temperature log analysis, The TDR (Time Domain Reflectometry) described in US Pat. No. 5,352,984, which is a relatively recent technology, is a technique for tracking and detecting underground leakage, but it is difficult to use and time consuming, and measurement results are inaccurate. PCT International Publication No. 2015076555 discloses a method for locating underground leakage sources through a metal ring connected to a voltage sensing electromagnetic sensor and a mobile tire reinforced with a hydrophobic fiber material. In the above invention, the fiber material surrounding the metal electrode uses a technique of reducing the electrical resistance of the interface between the surface of the leakage point and the electrode by supplying water. However, the above invention has the problem that the fiber material is not able to hold water on the surface thereof so as to reduce the interfacial electrical resistance, and the abrasion is severe due to the friction with the metal ring electrode, the fibrous material, and the ground. These problems lead to irregular electrical resistance between the leakage point and the electrodes, unbalanced movement of the tire / tread due to fiber wear during operation, signal interference and signal loss due to tire consumption become greater, fell. That is, the combination of tire and hydrophobic fiber connected to a certain metal ring electrode is unsatisfactory as a measure for detecting a short circuit from underground.

In order to solve this problem, the present inventors have focused on using a metal electrode and an electrically conductive but hydrophilic and elastic material for minimizing signal loss and durability for a long time. Tires made from these materials can function as mobile trailers that are connected to a leak sensor to detect a short circuit. To this end, the inventors have experimented with a wide range of elastomers. Typically, natural rubber (NR) is used as a material for manufacturing tires. Natural rubber imparts high green strength and elasticity to the final tire product, but NR is oxidized to double bonds present in the skeleton of NR ( Polymer handbook . Vol. 7 (1989)). U.S. Patent No. 6,032,642 uses an isoprene-butadiene rubber (IBR) copolymer having a high glass transition temperature in rubbers for tire treads, which can be used without a second matrix for emulsification, such as styrene-butadiene rubber (SBR) It can be used in combination with silica. U.S. Patent No. 2821232 discloses NR for super abrasion furnace carbon black or tire tread reinforced only with a combination of SAP and silica. However, as is well known in the art, the rubber for tire tread disclosed above is not suitable because the abrasion, tractive force, and rolling resistance that cause energy loss become worse when only one type of rubber matrix is present.

(BR), cis 1,4-polyisoprene rubber (IR), styrene butadiene rubber (SBR), acrylonitrile rubber (NBR), and other synthetic elastomers blends of NR and other synthetic elastomers. And an ethylene-propylene copolymer (EPDM) have been introduced and a reinforcing material has been incorporated to balance the physical properties of the tire. For example, it is known that mono or hybrid carbon-based fillers such as carbon black, nanotubes, graphene, etc., in combination with silanized-silica are most effective as the types of reinforcing materials. Most components can vary in polarity or nonpolarity, but conventional tire tread compositions are totally hydrophobic and therefore not suitable for conductive hydrophilic tires pursued by the present inventors.

To prepare a conductive hydrophilic tire composition it may be desirable to include a polar elastomer that is a water-swellable / water-absorbing material. Such materials include crosslinked polyvinyl alcohol, crosslinked polyacrylates, crosslinked starch-acrylate copolymers, crosslinked carboxymethylcellulose or water-expanding urethane resins. However, water-swellable or water-absorbing elastomeric compounds have several problems, and water-absorbing polymers such as crosslinked sodium polyacrylate can form a slippery gel on the surface of the vulcanizate upon absorption of water. In such cases, the mechanical strength and other physical-mechanical properties can be significantly reduced, which can reduce conventional tire properties (abrasion, traction, and elasticity).

SUMMARY OF THE INVENTION It is an object of the present invention to overcome the drawbacks of the prior art, and one of the various objects of the present invention is to provide a rubber composition which is capable of absorbing water and recovering its original weight upon drying, The present invention is to provide a tire made of a material having characteristics such as abrasion, pulling force and tensile strength, and to provide a method for detecting underground leakage by using the tire.

In order to solve the above-mentioned problems, the tire composition according to the present invention is characterized in that it comprises a carboxylated-acrylonitrile-butadiene rubber (XNBR), a fluoroelastomer (FKM), and epichlorohydrin polyethylene oxide allyl glycidyl ether ) And one or more water-swellable substances selected from polyacrylonitrile (PAN), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), and polyethylene oxide (PEO) And has mechanical properties of conventional tires, while having electrical conductivity and water-expandable characteristics. The tire composition according to the present invention expands when contacted with water and supplies moisture to the interface between the tire and the ground to easily pass the electric current generated from the underground defects, so that the electric leak sensor can sense the electric signal.

One of the various effects according to the present invention is that the conductive tire composition has very high electrical conductivity and has all the characteristics of a conventional tire.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram for manufacturing a tire with a tire composition according to the present invention. FIG.
2 is a plan view of a tire on which a specific circuit is arranged.
3 is a side view comparing the present invention with (Y) conventional technique (X).

Various embodiments and / or aspects are now described with reference to the drawings. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more aspects. However, it will also be appreciated by those of ordinary skill in the art that such aspect (s) may be practiced without these specific details. The following description and the annexed drawings set forth in detail certain illustrative aspects of one or more aspects. It is to be understood, however, that such aspects are illustrative and that some of the various ways of practicing various aspects of the principles of various aspects may be utilized, and that the description set forth is intended to include all such aspects and their equivalents.

In addition, the term "or" is intended to mean " exclusive or " That is, it is intended to mean one of the natural inclusive substitutions "X uses A or B ", unless otherwise specified or unclear in context. That is, X uses A; X uses B; Or when X uses both A and B, "X uses A or B" can be applied to either of these cases. It should also be understood that the term "and / or" as used herein refers to and includes all possible combinations of one or more of the listed related items.

It is also to be understood that the term " comprises "and / or" comprising " means that the feature and / or component is present, but does not exclude the presence or addition of one or more other features, components and / It should be understood that it does not. Also, unless the context clearly dictates otherwise or to the contrary, the singular forms in this specification and claims should generally be construed to mean "one or more. &Quot;

The present disclosure relates to a conductive hydrophilic tire composition having excellent electrical conductivity and water absorption properties and improved wear resistance, which can be used as a movable electrode, connected to a sensor for detecting underground leakage, and a method for manufacturing the same.

1, a is a state before the composition of the present invention is cured, b is a direction of a tread layer to which the composition of the present invention is applied, c is a manufactured tire tread, d is a hot-press vulcanization chamber, e is the rim of the tire, and f is the tire after curing.

In the arrangement of FIG. 2, the reference tire T may be connected to three different conductive tires T1, T2, T3. The reference tire T can be detected by receiving a short-circuit source V1, V2, V3 from a metal electrode connected to each tire.

FIG. 3X shows a conventional tire. Since the component b is made of a hydrophobic material, the interface e can not be wetted when the water is supplied, so that the interface resistance between the electrical leak source and the metal electrode is high and acts as an insulating material. it's difficult. In Fig. 3Y, if component g is hydrophilic or water-swellable and water is present, interface I can absorb water to form a thin water film. R1 and R2 denote the resistance in the underground leakage current source S, and J and K denote the ground resistance generated from e and I, respectively.

The conductive hydrophilic tire composition according to the present invention is characterized by comprising the following materials.

[Rubber Blend]

The rubber blend used in the tire composition according to the present invention is a blend of at least one polar rubber.

In a first embodiment of the present invention, the rubber blend is a mixture of 10 to 90 parts by weight of epoxidized natural rubber (ENR) having a weak polarity and 10 to 90 parts by weight of a strong polar synthetic elastomer. The ratio of the ENR to the synthetic elastomer is from 9: 1 to 1: 9, preferably from 1: 9 to 3: 7. The ENR contains about 25 to 40 mol% of epoxide groups. The synthetic elastomer is one selected from carboxymethyl-acrylonitrile butadiene rubber (XNBR), fluoroelastomer (FKM) and epichlorohydrin polyethylene oxide allyl glycidyl ether (GECO). The carboxyl group content in the XNBR is 0.05 to 0.085%, preferably 0.0721%, and the acrylonitrile content is 25 to 28%, preferably 26.43%. The XNBR has a Mooney viscosity (ML1 + 4) of 40 to 55, preferably 49. The GECO is a trimer of epichlorohydrin (CO), ethylene oxide (EO), and allyl glycidyl ether (AGE). The amount of chlorine (in CO) is 18 to 20% (In the AGE) by 6 to 8%, and EO by 10 to 30%, preferably about 25%. It is desirable to incorporate a polar group such as an oxygenated group into the structure of the elastomer to make the elastomer more polar. The inclusion of the oxygenated groups can promote the dispersion in the rubber blend of the elastomer and effectively increase the bond strength between the rubber blend and the reinforcement.

In a second embodiment of the present invention, the rubber blend is a blend of at least two polar rubbers selected from XNBR, FKM, and GECO. When the two types of synthetic elastomers are contained in this manner, they can have higher strength and polarity than the conventional hydrophobic synthetic elastomer, and thus are more preferable for achieving the object of the present invention. The ratio (GECO: XNBR, GECO: FKM, or FKM: XNBR) of the two synthetic elastomers is 9: 1 to 1: 9, preferably 9: 1 to 7: 3.

A third embodiment of the present invention is a thermoplastic polymer composition comprising at least one polar rubber selected from XNBR, FKM and GECO and at least one thermosetting polymer rubber selected from ethylene-vinyl acetate (EVA), polyvinyl chloride (PVC) and polyurethane ≪ / RTI > The use of such a blend can achieve better oxidation resistance and mechanical strength. These synthetic elastomeric structures can form hard solids, soft elastomers, or foams, but it is preferred to form hard solids or foams to achieve the objects of the present invention. The ratio of the thermosetting polymer rubber to the polar rubber (for example, PU: XNBR and PU: FKM) is 9: 1 to 1: 9, preferably 1: 9 to 7: 3.

<Reinforcement material>

If the rubber blend does not contain a reinforcing material, it is difficult to use the tire because of poor physical-mechanical properties. It is therefore desirable to add a stiffener to increase the germinability and, in some cases, to increase the thermal and electrical properties. The tire composition according to the present invention comprises about 5 to 30 parts by weight of reinforcing material based on 100 parts by weight of the total components. The reinforcing material may include silane-silica and carbon-based fillers such as graphene oxide, carbon black, carbon nanotubes, and the like, and these components exhibit a synergistic effect with each other.

1. Carbon black

The reinforcing material included in the first embodiment is carbon black. The carbon black may include at least one kind of carbon black. The first carbon black has a BET surface area of about 1270 m &lt; 2 &gt; / g when measured by Brunner, Emmett, Teller surface area (hereinafter "BET surface area") using nitrogen gas, Preferably 20 to 30 parts by weight, per 100 parts by weight of the composition. The carbon black has a DBP (value representing the structure of the reinforcing filler) of 480 to 510 mL / 100 g, preferably 498 mL / 100 g.

The second carbon black has a BET surface area of 35 to 45 m &lt; 2 &gt; / g, preferably 35 to 40 m &lt; 2 &gt; / g and comprises 5 to 15 parts by weight, preferably 5 to 10 parts by weight, based on 100 parts by weight of the total rubber component . The second carbon black has an I2 moisture absorption amount (iodine absorption amount representing the surface area of the reinforcing material) of about 37 to 47 g / kg, preferably 42.5 g / kg when measured according to ASTM D1510. The second carbon black has a statistical surface area (STSA) of 38.7 m 2 / g with a pH of 6 to 10, preferably 7.3, as measured according to ASTM D6556. Since the DBP value and the I2 absorption amount are main factors determining the physical properties and chemical properties of the carbon black, it is difficult to expect the improvement of the electric conductivity when the DBP value of the carbon black and the I2 absorption amount and the addition amount are out of the above range.

The third carbon black has a BET surface area of 100 to 121 m &lt; 2 &gt; / g. The third carbon black has an I2 moisture absorption of about 116 to 126 g / kg, preferably 123.3 g / kg, as measured according to ASTM D1510. The pH of the third carbon black is about 6 to 10, preferably about 8. When the third carbon black is included, the first carbon black may be included in an amount of 20 to 25 parts by weight based on 100 parts by weight of the total rubber component, and the second and third carbon black may be included in an amount of about 5 to 10 parts by weight . The third carbon black may be included in place of the second carbon black. If the total amount of carbon black does not fall within the above-mentioned range, it is not preferable because it is difficult to expect an improvement in electric conductivity. If the total amount exceeds the specified range, the reinforcing property of the tire tread is lowered.

2. Silica

The reinforcing material included in the first embodiment is fine pulverized silica. The silica may be included in an amount of 5 to 15 parts by weight, preferably 5 to 10 parts by weight, based on 100 parts by weight of the total rubber component. If the amount is less than 5 parts by weight, the effect of reducing the rotational resistance due to the addition of silica is insufficient, and if it exceeds 15 parts by weight, the effect of improving the electrical conductivity by the carbon black used in the present invention is hindered. The silica has a BET surface area of about 150 to 200 m 2 / g, preferably 164 m 2 / g. The BET surface area herein means the total surface area, including the porosity of the reinforcing material. The silica has a pH of from 0 to 13, preferably 11.2. Since the BET value and the like are the main factors that determine the characteristics of silica, if the BET value of silica etc. deviates from the specified range, the processability is deteriorated, which is not preferable.

A coupling agent may be added to improve the dispersion of silica. The coupling agent helps to uniformly disperse the silica particles on the rubber, while maintaining a strong bond between the rubber and the silica. The most commonly used coupling agent is a silane coupling agent, but the type of coupling agent may vary depending on the materials used and the process conditions. Because silica is small in molecular weight and can form chemical bonds with polymer particles, they must contain functional groups that react the filler with the matrix. The coupling agent is contained in an amount of about 3 to 12 parts by weight, preferably 3 to 6 parts by weight, based on 100 parts by weight of the total composition.

3. Graphene oxide

In order to increase the strength and polarity of the composition, the tire composition according to the present invention may contain 0.1 to 1 part by weight of graphene oxide based on 100 parts by weight of the total rubber component. The graphene oxide is preferably reduced graphene oxide (RGO) having a BET surface area of at least about 450 m &lt; 2 &gt; / g.

There may be embodiments in which the reinforcement material is the same as the reinforcement material included in the first embodiment described above but the rubber blend component or blend ratio is different.

<Water-Expansion Material>

The polymeric material may be selected from the group consisting of crosslinked polyvinyl alcohol, crosslinked polyacrylate, crosslinked starch-acrylate copolymer, crosslinked carboxymethylcellulose, polyacrylonitrile (PAN), polyvinyl alcohol (PVA), polyvinylpyrrolidone Polyvinylpyrrolidone (PVP), polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), polymethyl methacrylate (PMMA), polyacrylic acid, polyurethane polyurethane, polyurethane, or a combination thereof, all including water-swelling materials known in the art. The degree of water solubility and degree of expansion thereof can be adjusted in consideration of the degree of hydrolysis, the thickness, and the like. The water-swellable material may be included in an amount of 20 to 30 parts by weight based on 100 parts by weight of the total rubber component.

<Additives>

The tire composition according to the present invention may further comprise conventional additives known in the rubber / tire industry. Examples of such additives include, but are not limited to, sulfur vulcanizing agents, accelerators, activators, antioxidants, waxes, process oils, and the like. These additive (s) are included in amounts known per se in the rubber / tire industry and are known in the art. For example, the composition of the present invention may include a plasticizer to lower the viscosity of the composition of the present invention and to reduce the energy required for the process. Examples of plasticizers are mineral oils, which consist of hydrocarbons which are mixtures of aromatic, naphthalenic and paraffinic structures. Depending on the polarity of the carbon polymer used, plasticizers of polar or non-polar type may be used. The nonpolar oil may be selected from Mild Extracted Solvent (MES), Residual Aromatic Extracted Solvent (RAE), and Treated Distillate Aromatic Extracted Solvent (TDAE). Hydrophilic oils can be synthetic oils as described in U.S. Pat. Nos. 6,248,929, 6,399,697, and 6,108,166, or derivatives of phthalic acid, adipic acid, or sebacic acid.

In the tire composition according to the present invention, the content of the polar oil or the non-polar oil is about 5 to 15 parts by weight, preferably 10 parts by weight, based on 100 parts by weight of the total rubber component. Outside of this range, the mechanical properties and elasticity can be reduced. For example, the tire composition according to the present invention has an aromatic oil having a density of 0.9530 at 15 DEG C (based on ASTM D4052) and a viscosity of 19.29 (based on ASTM D445) at 100 DEG C, in an amount of 5 to 15 parts by weight, Preferably 5 to 10 parts by weight.

The tire composition according to the present invention has a resistance of 25 to 70 [Omega] cm, preferably 40 [Omega] cm, and has an expansion degree of 20 to 70%, preferably an expansion degree of 40% within 1 minute. The tire composition according to the invention has a wear resistance of 100 to 200 mm 3, preferably 160 mm 3, and a tensile strength of 10 to 22 MPa, preferably 12 MPa.

<Manufacturing Method>

In order to produce the tire composition according to the present invention, the rubber blend and the reinforcing material are mixed (first mixing step) except for the accelerator, the activator and the curing agent, and then the accelerator, the activator and / or the curing agent are mixed (Second mixing step). The first mixing step is preferably carried out at about 90 ° C for 5 minutes and the second mixing step is carried out at about 50 ° C for 2 minutes.

In order to achieve optimum physical-mechanical properties and obtain a homogeneous mixture, it is desirable to subject the rubber component and other components to a two-roll mill for a controlled period of time. In the present invention, the time to pass through the double-roll mill is suitably 5 to 20 minutes, preferably 10 to 15 minutes. The temperature in the double-roll mill is determined according to the properties of the desired composition, but usually 25 to 120 ° C is suitable, and 25 to 50 ° C is preferred.

The mixed composition is then sheeted out and vulcanized at 100-190 占 폚, preferably 120-160 占 폚, in a moving diaometer. The optimal vulcanization characteristics can be modified so that the resulting sample has desirable standard properties. Finally, 2.5 to 5 MPa, preferably 5 MPa, is applied to the hot-press and subjected to standard procedures.

<Examples>

The following examples are intended to illustrate the present invention only, and the scope of protection of the present invention is not limited by these examples. The abbreviations described in the following Comparative Examples and Examples mean the following.

NR: natural rubber;

BR: cis-1,4-polybutadiene rubber

SBR: styrene-butadiene rubber;

XNBR: Carboxylated acrylonitrile butadiene rubber

ENR: Epoxidized natural rubber

GECO: Epichlorohydrin Polyethylene oxide allyl glycidyl ether

PU: Polyurethane

IR: polyisoprene rubber

PVP: polyvinylpyrrolidone

CSP: crosslinked sodium polyacrylate

CF: Cellulose fiber

TMTD: Tetramethyl thiuram disulfide;

CZ: N-cyclohexyl-2-benzothiazole sulfonamide;

S / T: stearic acid;

6PPD: 1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine;

TMQ: 2,2,4-trimethyl-1,2-dihydroquinoline polymer;

1. Preparation of tire composition

The tire compositions according to the present invention were prepared in the following materials and composition ratios. S1 corresponds to a commercial standard tire composition according to the prior art, and A1, A2, B1, B2, C1, and C2 correspond to the tire composition according to the present invention.

2. Property evaluation

The properties of the tire composition and the commercial standard tire composition of the examples were measured. The properties of each tire sample were cut to an appropriate size and then subjected to strength tests, electrical resistance measurements, abrasion resistance, and water-swelling tests. In the water-swell test, the sample was cut to a thickness of about 3 cm x 3 cm, 2 mm, and then the initial weight was measured, and then the weight was taken after the water was absorbed. The degree of swelling was calculated by the following equation.

(Where v is the initial weight and u is the final weight).

As can be seen from the above table, compositions A1, A2, B1, B2, C1, and C2 according to the present invention are not electrically conductive, (Very low electrical resistance). Particularly, C2 shows excellent properties such as water swelling and abrasion as well as low electrical resistance, and thus it can be understood that the object of the present invention is best satisfied.

Thus, when a tire is manufactured using the tire composition according to the present invention, the underground leakage source can be effectively measured, the sensor action can be maintained until the life of the tire is completed, and the leakage source can be directly measured So that a remarkably accurate measurement is possible than in the prior art.

The description of the presented embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features presented herein.

Claims (1)

At least one polar rubber selected from carboxylated-acrylonitrile-butadiene rubber (XNBR), fluoroelastomer (FKM), and epichlorohydrin polyethylene oxide allyl glycidyl ether (GECO);
20 to 30 parts by weight of at least one water-swelling material selected from polyacrylonitrile (PAN), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), and polyethylene oxide (PEO) Weight basis);
5 to 30 parts by weight of at least one kind of carbon black (based on 100 parts by weight of total rubber components); And
5 to 15 parts by weight of silica (based on 100 parts by weight of total rubber components)
&Lt; / RTI &gt;

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