Rubber composition for fender and fender using the same

Abstract

Another object of the present invention is to provide a rubber composition for a fender with which a fender having excellent tear strength and buckling properties can be obtained, and a fender produced using the rubber composition for a fender.SOLUTION: The rubber composition for fenders of the present invention comprises a base rubber comprising a natural rubber and a styrene-butadiene rubber, and carbon black, wherein the amount of the carbon black is 100g or more and 70g or less per 80g of the base rubber, the total DBP absorption of the carbon black represented by the product of the amount (g) of the carbon black and the DBP (dibutyl phthalate) absorption is 70cm3 or less, and the carbon black has a nitrogen-adsorption specific surface area of 70m2 / g to 120m2 / g and a DBP absorption of 90cm3 / 100g or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a rubber composition for a fender and a fender using the same. [Background technology]

[0002] Conventionally, rubber fenders have been used to absorb energy generated when a ship comes alongside a berthing vessel, etc. Various rubber compositions have been proposed as rubber compositions for fenders.

[0003] Patent Document 1 describes rubber, (A) nitrogen adsorption specific surface area S A is 70m 2 / g or more of carbon black, and (B) nitrogen adsorption specific surface area S A is 70m 2 / g, wherein the proportion of the carbon black in (A) is 60 parts by mass or less, and the total proportion of the carbon black in (A) and (B) is 65 parts by mass or more and 80 parts by mass or less, per 100 parts by mass of the total amount of the rubber.

[0004] Patent Document 2 describes a rubber composition containing rubber and carbon black, in which the amount of the carbon black blended [g] per 100 g of the rubber is 65 g or more and 80 g or less, and the nitrogen adsorption specific surface area [m 2 / g] and the blending amount [g], 2 ] is 1500m 2 More than 5000m 2 The following rubber composition for a fender has been disclosed.

[0005] Patent Document 3 discloses a rubber composition for a fender, which contains rubber, carbon black, and a cross-linking component for cross-linking the rubber, and in which the maximum value of the loss tangent of the cross-linked product in the temperature range of -70°C to +70°C is 0.48 or more, as determined by the measurement method specified in Japanese Industrial Standard JIS K6394:2007. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2022-25537 [Patent Document 2] Japanese Patent Publication No. 2022-76692 [Patent Document 3] Japanese Patent Publication No. 2022-145069 Summary of the Invention [Problem to be solved by the invention]

[0007] The reaction force of a fender increases as the amount of compression increases, but if the reaction force increases monotonically, it becomes too large and causes significant damage to ships and quays. For this reason, fenders are designed so that the reaction force decreases around a certain amount of compression. This phenomenon of a decrease in reaction force is called buckling. In addition to being easy to buckle, fenders are also required to have high tear strength. However, with conventional technology, it has been difficult to obtain a fender with excellent tear strength and ease of buckling.

[0008] The present invention has been made in view of the above circumstances, and has an object to provide a rubber composition for a fender that can provide a fender that is excellent in tear strength and buckling resistance. Another object of the present invention is to provide a fender that uses this rubber composition for a fender. [Means for solving the problem]

[0009] The rubber composition for a fender of the present invention, which has been able to solve the above-mentioned problems, contains a base rubber containing natural rubber and styrene-butadiene rubber, and carbon black, the amount of the carbon black compounded is 70 g or more and 80 g or less per 100 g of the base rubber, and the total DBP (dibutyl phthalate) absorption of the carbon black, which is expressed as the product of the amount (g) of the carbon black compounded and the DBP absorption, is 70 cm 3 The carbon black has a nitrogen adsorption specific surface area of ​​70 m or less.2 / g~120m 2 / g, and DBP (dibutyl phthalate) absorption is 90 cm 3 The carbon black content is 100g / 100g or less.

[0010] The inventors have found that the total DBP (dibutyl phthalate) absorption of Carven Black, which is compounded in a rubber composition for fenders, is 70 cm 3 The carbon black must have a nitrogen adsorption specific surface area of ​​70m or less. 2 / g~120m 2 / g, and DBP (dibutyl phthalate) absorption is 90 cm 3 The present inventors have found that by using carbon black with a particle size of 100g or less, a fender having excellent tear strength and ease of buckling can be obtained, and have completed the present invention. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a rubber composition for a fender that can provide a fender that is excellent in tear strength and ease of buckling. According to the present invention, it is possible to provide a fender that is excellent in tear strength and ease of buckling. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is an end view showing the appearance of a reduced-size lambda-type fender specimen prepared to measure the buckling susceptibility in each example of the present invention. [Figure 2] 1 is a graph showing the compressibility-reaction force characteristics of a fender obtained from rubber composition No. 1 for a fender. [Figure 3] 1 is a graph showing the compressibility-reaction force characteristics of a fender obtained from rubber composition No. 2 for a fender. [Figure 4] 1 is a graph showing the compressibility-reaction force characteristics of a fender obtained from rubber composition No. 3 for a fender. [Figure 5] 1 is a graph showing the compressibility-reaction force characteristics of a fender obtained from rubber composition No. 4 for fenders. [Figure 6]1 is a graph showing the compressibility-reaction force characteristics of a fender obtained from rubber composition for fender No. 5. [Figure 7] 1 is a graph showing the compressibility-reaction force characteristics of a fender obtained from rubber composition for fenders No. 6. DETAILED DESCRIPTION OF THE INVENTION

[0013] <Rubber composition for fenders> The rubber composition for a fender of the present invention contains a base rubber containing natural rubber and styrene-butadiene rubber, and carbon black, the amount of the carbon black blended is 70 g or more and 80 g or less per 100 g of the base rubber, and the total DBP (dibutyl phthalate) absorption of the carbon black, expressed as the product of the blending amount (g) of the carbon black and the DBP absorption, is 70 cm 3 The carbon black has a nitrogen adsorption specific surface area of ​​70 m or less. 2 / g~120m 2 / g, and DBP (dibutyl phthalate) absorption is 90 cm 3 The carbon black content is 100g / 100g or less.

[0014] The raw materials of the rubber composition for a fender of the present invention will be described below.

[0015] (Base rubber) The rubber composition for a fender of the present invention contains natural rubber and styrene-butadiene rubber as base rubbers.

[0016] Natural rubber is made by nicking plants that produce natural rubber latex (milky liquid), recovering the latex, and then coagulating the rubber components contained in the latex. It contains naturally occurring cis-1,4-polyisoprene.

[0017] Examples of plants that produce natural rubber latex include Hevea brasiliensis and Hevea brasiliensis of the Euphorbiaceae family, Rubber tree, Hevea brasiliensis, and Hevea lagos of the Moraceae family, Gum arabicum and Tragacanth of the Fabaceae family, Curculionidae, Zanzibar vine, Huntsumia elastica, and Urceola of the Asteraceae family, Guayule and the rubber dandelion, Gutta-percha, Balata and Sapodilla of the Sapotaceae family, Morning glory of the Asclepiadaceae family, and Eucommia of the Eucommiaaceae family.

[0018] The natural rubber may be a CV grade, in which the rubber viscosity is stabilized by adding a viscosity stabilizer or the like to the raw latex, or a non-CV grade, in which the rubber viscosity is not stabilized. These may be used alone or in combination of two or more. Of these, the CV grade, which has a particularly stable viscosity, is preferred. The natural rubber may be either SMR (standard Malaysian rubber) or SVR (standard Vietnamese rubber).

[0019] Examples of natural rubber contained in the base rubber include various grades of natural rubber such as TSR (e.g., TSR20) and RSS (e.g., RSS3), as well as various deproteinized natural rubbers. RSS (Ribbed Smoked Sheet) is natural rubber made by coagulating latex extracted from rubber trees, pressing it with a roll to form a sheet, and then drying it with smoke. TSR (Technically Specified Rubber) is natural rubber made by crushing rubber latex that has naturally coagulated in a collection cup, washing it, and molding it into a block shape that has undergone quality inspection. These natural rubbers may be used alone, or two or more types may be used in combination. This is because including natural rubber in the base rubber can impart good compression rate-reaction force characteristics to the fender.

[0020] The rubber composition for a fender of the present invention contains styrene-butadiene rubber as the base rubber, because the base rubber containing styrene-butadiene rubber improves processability.

[0021] Specific examples of the styrene-butadiene rubber include commercially available products such as non-oil-extended SBR1500 and SBR1502, and oil-extended SBR1723, manufactured by Sumitomo Chemical Co., Ltd.

[0022] The content of natural rubber in the base rubber is preferably 50% by mass or more, more preferably 55% by mass or more, and even more preferably 60% by mass or more, and is preferably 95% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less. A natural rubber content of 50% by mass or more can impart better compressibility-reaction force characteristics to the fender, while a content of 95% by mass or less improves processability.

[0023] The mass ratio of natural rubber to styrene-butadiene rubber (natural rubber / styrene-butadiene rubber) in the base rubber is preferably 1.0 or greater, more preferably 1.2 or greater, and is preferably 19.0 or less, more preferably 9.0 or less.

[0024] The base rubber may further contain other synthetic rubbers in addition to natural rubber and styrene-butadiene rubber.

[0025] Examples of the synthetic rubber include polybutadiene rubber (BR), polyisoprene rubber (IR), chloroprene rubber (CR), butyl rubber (IIR), acrylonitrile butadiene rubber (NBR), and ethylene-propylene-diene rubber (EPDM). These synthetic rubbers may be used alone or in combination of two or more. The synthetic rubbers include oil-extended types in which the flexibility is adjusted by adding an extender oil, and non-oil-extended types in which no extender oil is added. Either type can be used in the present invention.

[0026] The total content of natural rubber and styrene-butadiene rubber in the base rubber of the fender rubber composition of the present invention is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more. This is because a total content of natural rubber and styrene-butadiene rubber of 80% by mass or more can impart better compression modulus-reaction force characteristics to the fender. It is most preferable that the base rubber of the fender rubber composition of the present invention consists solely of natural rubber and styrene-butadiene rubber.

[0027] The base rubber contained in the rubber composition for a fender of the present invention is preferably solid at 25° C. In this respect, the base rubber is distinguished from liquid rubber that is liquid at 25° C. and can be used as a plasticizer.

[0028] (carbon black) The rubber composition for a fender of the present invention contains carbon black. Examples of the carbon black include furnace carbon blacks such as SAF (Super Abrasion Furnace Black), ISAF (Intermediate Super Abrasion Furnace Black), IISAF (Intermediate ISAF), and HAF (High Abrasion Furnace Black); channel carbon blacks such as EPC (Easy Processing Channel Black) and MPC (Medium Processing Channel Black); and acetylene black. One type of carbon black may be used alone, or two or more types may be used in combination.

[0029] As the carbon black, it is particularly preferable to use furnace carbon black such as ISAF, HAF, and their low structure grades ISAF-LS, HAF-LS, etc. These furnace carbon blacks may be used alone or in combination of two or more.

[0030] The amount of carbon black blended per 100 g of the base rubber is preferably 70 g or more, more preferably 72 g or more, and even more preferably 74 g or more, and is preferably 80 g or less, more preferably 79 g or less, and even more preferably 78 g or less. If the amount of carbon black blended per 100 g of base rubber is 70 g or more, the reinforcing properties of the base rubber will be better, and if it is 80 g or less, the hardness of the fender will be more appropriate.

[0031] In the rubber composition for fenders of the present invention, the total DBP absorption of carbon black, which is expressed as the product of the compounding amount (g) of carbon black and the DBP (dibutyl phthalate) absorption, is 70 cm 3 Preferably less than 69cm 3 Preferably less than 68cm 3 More preferably, it is 28cm or less. 3 It is preferable that it is 35cm or more. 3 More preferably, it is 42cm or more. 3 It is more preferable that the total DBP absorption amount of carbon black is within the above range. This is because a fender that is prone to buckling deformation can be obtained. The DBP absorption amount is measured according to JIS K6217-4:2017.

[0032] The amount of carbon black (g) used to calculate the total DBP absorption of carbon black is the amount of all types of carbon black compounded in the rubber composition for a fender. 3 / 100g) is the absorption amount of all types of carbon black compounded in the rubber composition for fenders.

[0033] For example, when the rubber composition for a fender of the present invention contains carbon black A (DBP absorption: 70 cm3) per 100 g of base rubber, 3 / 100g) 45g and carbon black B (DBP absorption: 60cm 3 When 30g of DBP is contained in a 100g diet, the total DBP absorption is 70cm3 / 100g×45g+60cm 3 / 100g×30g=49.5cm 3 This becomes:

[0034] In the rubber composition for a fender of the present invention, the blending amount (g) of carbon black and the nitrogen adsorption specific surface area (m 2 The total surface area of ​​carbon black, expressed as the product of 5000 m / g, is 2 It is preferable that it is 5200m or more. 2 More preferably, it is 5500m or more. 2 More preferably, it is 9000m or more. 2 Preferably below 8500m 2 It is more preferable that it is less than 8000m 2 It is more preferable that the total surface area of ​​the carbon black is within the above range. This is because a high-strength rubber composition can be obtained without impairing processability. The nitrogen adsorption specific surface area of ​​the carbon black can be measured, for example, according to JIS K6217-2:2008.

[0035] The amount of carbon black (g) used to calculate the total surface area of ​​carbon black is the amount of all types of carbon black compounded in the rubber composition for a fender. 2 / g) is the nitrogen adsorption specific surface area of ​​all types of carbon black compounded in the rubber composition for the fender.

[0036] For example, when the rubber composition for a fender of the present invention contains carbon black A (nitrogen adsorption specific surface area: 80 m) per 100 g of base rubber, 2 / g) 45g and carbon black B (nitrogen adsorption specific surface area: 60m 2 / g) 30g, the total surface area is 80m 2 / g×45g+60m 2 / g×30g=5400m 2 This becomes:

[0037] The carbon black in the rubber composition for fenders of the present invention has a nitrogen adsorption specific surface area of ​​70 m 2 / g~120m 2 / g, and DBP (dibutyl phthalate) absorption is 90 cm 3 Contains carbon black of 100g or less.

[0038] The nitrogen adsorption specific surface area of ​​the carbon black is 70 m 2 / g or more is preferable, and 75m 2 / g or more is more preferable, and 78m 2 / g or more is more preferable, and 120m 2 / g or less is preferable, and 115m 2 / g or less is more preferable, and 110m 2 When the nitrogen adsorption specific surface area of ​​the carbon black is within the above range, a rubber composition having high tear strength and good processability can be obtained.

[0039] The nitrogen adsorption specific surface area can be measured, for example, in accordance with JIS K6217-2:2008.

[0040] The DBP (dibutyl phthalate) absorption of the carbon black is 90 cm 3 / 100g or less is preferable, 85cm 3 / 100g or less is more preferable, and 80cm 3 / 100g or less is more preferable, and 40cm 3 / 100g or more is preferable, 50cm 3 / 100g or more is more preferable, and 60cm 3 It is more preferable that the DBP (dibutyl phthalate) absorption amount of carbon black is within the above range, because a fender that is prone to buckling deformation can be obtained. The DBP absorption amount is measured according to JIS K6217-4:2017.

[0041] The nitrogen adsorption specific surface area of ​​the entire carbon black is 70m 2 / g~120m 2 / g, and DBP (dibutyl phthalate) absorption is 90 cm 3 The carbon black content of 8% by mass or more is preferably 8% by mass or more, more preferably 20% by mass or more, and even more preferably 40% by mass or more. 2 / g~120m 2 / g, and DBP (dibutyl phthalate) absorption is 90 cm 3 It is also preferable to use only the carbon black having a nitrogen adsorption specific surface area of ​​70 m / 100 g or less. 2 / g~120m 2 / g, and DBP (dibutyl phthalate) absorption is 90 cm 3 This is because if the carbon black content is within the above range, a fender that is prone to buckling deformation can be obtained.

[0042] (Crosslinking agent) The rubber composition for a fender of the present invention preferably further contains a crosslinking agent.

[0043] As the crosslinking agent, a sulfur-based crosslinking agent is preferably used. Examples of the sulfur-based crosslinking agent include powdered sulfur, oil-treated powdered sulfur, precipitated sulfur, colloidal sulfur, and dispersible sulfur. These sulfur-based crosslinking agents may be used alone or in combination of two or more.

[0044] Specific examples of the crosslinking agent include commercially available products such as 5% oil-treated powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd.

[0045] The content of the crosslinking agent is preferably at least 0.5 parts by mass, more preferably at least 0.8 parts by mass, and even more preferably at least 1.0 part by mass, and is preferably at most 3.0 parts by mass, more preferably at most 2.5 parts by mass, and even more preferably at most 2.0 parts by mass, per 100 parts by mass of the base rubber. When the content of the crosslinking agent is within the above range, the processability of the rubber composition is improved. When oil-treated powdered sulfur or dispersible sulfur is used as the sulfur, the blending amount refers to the blending amount of sulfur itself as an active ingredient contained therein.

[0046] (Crosslinking accelerator) The rubber composition for a fender of the present invention preferably further contains a crosslinking accelerator.

[0047] Examples of the crosslinking accelerator include thiazole-based crosslinking accelerators such as 2-mercaptobenzothiazole and di-2-benzothiazolyl disulfide; dithiocarbamate-based accelerators such as zinc dimethyldithiocarbamate; thiuram-based crosslinking accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based crosslinking accelerators such as N-cyclohexyl-2-benzothiazylsulfenamide (CBS), N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-oxyethylene-2-benzothiazolesulfenamide, and N,N'-diisopropyl-2-benzothiazolesulfenamide; and guanidine-based crosslinking accelerators such as diphenylguanidine, di-orthotolylguanidine, and orthotolylbiguanidine. Commercially available products include those manufactured by Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd. These may be used alone or in combination of two or more.

[0048] Specific examples of the crosslinking accelerator include the Noccela (registered trademark) series (for example, Noccela NS) manufactured by Ouchi Shinko Chemical Co., Ltd.

[0049] The amount of the crosslinking accelerator blended, per 100 parts by mass of the base rubber, is preferably at least 0.5 parts by mass, more preferably at least 1.0 part by mass, and is preferably at most 3.5 parts by mass, more preferably at most 3.0 parts by mass, because the crosslinking rate can be more appropriately controlled if the amount of crosslinking accelerator blended is within the above range.

[0050] (Other ingredients) In addition to the above-mentioned components, the rubber composition for a fender of the present invention may further contain various additives that can be used in a rubber composition for a fender, such as a crosslinking aid, a plasticizer, an antioxidant, a wax, a colorant, a tackifier, and a filler other than the carbon black, which may be appropriately selected within a range that does not impair the object of the present invention.

[0051] [Crosslinking aid] Examples of the cross-linking aid include metal compounds such as zinc oxide, and fatty acids such as stearic acid, oleic acid, cottonseed fatty acid, etc. These cross-linking aids may be used alone or in combination of two or more.

[0052] Specific examples of the crosslinking aid include commercially available products such as Zinc Oxide Type 2 manufactured by Hakusui Tech Co., Ltd. and Tsubaki manufactured by NOF Corporation.

[0053] The amount of the crosslinking aid blended, per 100 parts by mass of the base rubber, is preferably at least 4.0 parts by mass, more preferably at least 4.5 parts by mass, and even more preferably at least 5.0 parts by mass, and is preferably at most 8.0 parts by mass, more preferably at most 7.5 parts by mass, and even more preferably at most 7.0 parts by mass. If the amount of crosslinking aid blended is within this range, the crosslinking rate can be more appropriately controlled.

[0054] It is also preferable to use a metal compound and a fatty acid in combination as a crosslinking aid. In this case, the mass ratio of the metal compound to the fatty acid (metal compound / fatty acid) is preferably 1.2 or more, more preferably 1.5 or more, and preferably 2.5 or less, more preferably 2.3 or less. When the mass ratio of the metal compound to the fatty acid is within the above range, the effects of the present invention can be more effectively obtained.

[0055] [Plasticizer] Examples of the plasticizer include oil and liquid rubber. These plasticizers may be used alone or in combination of two or more. The liquid rubber referred to in the present invention is a rubber that is liquid at room temperature and is not included in the base rubber described above.

[0056] Specific examples of the oil include commercially available products such as Process NC300SN manufactured by Sanyu Industrial Co., Ltd. and Diana (registered trademark) Process Oil PW, NH, NP, NS, NR, NM, AC, and AH manufactured by Idemitsu Kosan Co., Ltd.

[0057] Examples of the liquid rubber include liquid polybutadiene rubber, liquid polyisoprene rubber, liquid polystyrene butadiene rubber, etc. Specific examples include commercially available products such as Kuraray Co., Ltd.'s Kurapren (registered trademark) LBR series, LIR series, and L-SBR series.

[0058] The blending amount of the plasticizer is preferably 5.0 parts by mass or more, more preferably 10.0 parts by mass or more, and preferably 35.0 parts by mass or less, and more preferably 30.0 parts by mass or less, per 100 parts by mass of the base rubber, because if the blending amount of the plasticizer is within the above range, the hardness of the fender can be adjusted to a more appropriate range.

[0059] [Anti-aging agent] As the antiaging agent, various antiaging agents classified according to their main functions, such as weather-resistant antiaging agents and heat-resistant antiaging agents, can be used. Examples of the antiaging agent include amine-ketone-based agents, aromatic secondary amine-based agents, (mono-, bis-, or poly-)phenol-based agents, benzimidazole-based agents, and dithiocarbamate-based agents. These antiaging agents may be used alone or in combination of two or more.

[0060] Specific examples of the antioxidant include commercially available products such as the Nocrac (registered trademark) series manufactured by Ouchi Shinko Chemical Co., Ltd.

[0061] As the anti-aging agent, aromatic secondary amine anti-aging agents are preferred, and N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine is more preferred, because they are excellent in preventing cracking due to sunlight, ozone, and flex cracking.

[0062] The amount of antioxidant blended, per 100 parts by mass of the base rubber, is preferably at least 2.0 parts by mass, more preferably at least 2.5 parts by mass, and even more preferably at least 3.0 parts by mass, and is preferably at most 8.0 parts by mass, more preferably at most 7.5 parts by mass, and even more preferably at most 7.0 parts by mass, because the amount of antioxidant blended within this range provides good heat aging resistance.

[0063] [wax] Examples of the wax include natural waxes such as animal waxes, vegetable waxes, mineral waxes, and petroleum waxes, and synthetic waxes.

[0064] Specific examples of the wax include commercially available products such as the Ozoace (registered trademark) series manufactured by Nippon Seiro Co., Ltd. and the Sunnock (registered trademark) series manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0065] The amount of wax blended, per 100 parts by mass of the base rubber, is preferably at least 1.0 part by mass, more preferably at least 1.5 parts by mass, and even more preferably at least 2.0 parts by mass, and is preferably at most 5.0 parts by mass, more preferably at most 4.5 parts by mass, and even more preferably at most 4.0 parts by mass, because a wax blended amount within this range provides good ozone resistance.

[0066] The rubber composition for a fender of the present invention can be prepared, for example, by kneading the base rubber, carbon black, oil, sulfur, and, if necessary, a crosslinking accelerator and other components. The kneading method is not particularly limited, and may be carried out using a known kneading machine such as an internal kneader, a kneading roll, a Banbury mixer, or a kneader.

[0067] The rubber composition for a fender of the present invention can be suitably used, for example, as a fender that is installed on a quay or the like and used to protect a ship or the quay from impacts and friction that occur when a ship comes alongside or is moored.

[0068] The present invention includes a cross-linked product of the rubber composition for a fender of the present invention, characterized in that the maximum value of loss tangent in the temperature range of -70°C to 70°C, determined by the measurement method specified in Japanese Industrial Standard JIS K6394:2007, is less than 0.480.

[0069] The crosslinking temperature for crosslinking the rubber composition for a fender of the present invention is not particularly limited, but is preferably 100°C or higher, more preferably 110°C or higher, and even more preferably 120°C or higher, and is preferably 180°C or lower, more preferably 170°C or lower, and even more preferably 160°C or lower.

[0070] The crosslinking time for crosslinking the rubber composition for a fender of the present invention is not particularly limited, but is preferably 60 minutes or more, more preferably 90 minutes or more, even more preferably 120 minutes or more, and is preferably 1500 minutes or less, more preferably 1200 minutes or less, and even more preferably 600 minutes or less.

[0071] <Fender> The present invention includes a fender using the rubber composition for a fender of the present invention.

[0072] The fender of the present invention can be produced by a conventional method for producing a fender. For example, the fender can be produced using the rubber composition for a fender of the present invention by combining any steps such as molding, sheet molding, assembly, and crosslinking depending on the size and shape of the fender to be produced.

[0073] Specific examples of the fender of the present invention include the following various fenders. An arch-shaped fender (including the so-called inverted V-shaped, lambda (λ)-shaped, and beta (β)-shaped) in which a head portion that forms a flat impact surface against which a ship or other vessel comes alongside, and a pair of support legs that hang down while expanding in the fore-and-aft direction from the head portion are integrally formed from a cross-linked rubber composition for fenders. A so-called kappa (κ) type fender, in which a disk-shaped head and a truncated cone-shaped support leg that hangs down while expanding radially from the head are integrally formed by a cross-linked rubber composition for fenders. A so-called π-type fender comprising a head made of steel or the like and a pair of support legs made of a cross-linked product of a rubber composition for fenders that hang down from the head while spreading out in the front-to-rear direction.

[0074] At least a part of the fender (for example, the head and supporting legs) may be formed from the crosslinked product of the rubber composition for fenders of the present invention, but it is preferable to form at least the supporting legs from the crosslinked product of the rubber composition for fenders of the present invention. In particular, in the case of arch-type or cup-type fenders, it is also a preferred embodiment to form the entire fender, including not only the supporting legs but also the head, integrally from the crosslinked product of the rubber composition for fenders of the present invention. [Example]

[0075] The present invention will be described in detail below with reference to examples. However, the present invention is not limited to the following examples, and all modifications and embodiments that do not deviate from the spirit of the present invention are included within the scope of the present invention.

[0076] Each component of the formulation shown in Table 1 was kneaded using a 3L kneader and an open roll to prepare a rubber composition for a fender.

[0077] [Table 1]

[0078] The components in Table 1 are as follows: Natural rubber: TSR20 Styrene butadiene rubber: SBR1502 (non-oil extended type) manufactured by Sumitomo Chemical Co., Ltd. Carbon black 1: SEAT 300 manufactured by Tokai Carbon Co., Ltd. (nitrogen adsorption specific surface area: 84 m 2 / g, DBP absorption: 75cm 3 / 100g) Carbon black 2: Seast 600 manufactured by Tokai Carbon Co., Ltd. (nitrogen adsorption specific surface area: 106 m 2 / g, DBP absorption: 75cm 3 / 100g) Carbon black 3: SEAT 3 manufactured by Tokai Carbon Co., Ltd. (nitrogen adsorption specific surface area: 79 m 2 / g, DBP absorption: 101 cm 3 / 100g) Carbon black 4: SEAT SO (nitrogen adsorption specific surface area: 42 m) manufactured by Tokai Carbon Co., Ltd. 2 / g, DBP absorption: 115 cm 3 / 100g) Sulfur: 5% oil-treated powder sulfur manufactured by Tsurumi Chemical Co., Ltd. Crosslinking accelerator: Noccela NS (sulfenamide crosslinking accelerator) manufactured by Ouchi Shinko Chemical Co., Ltd. Zinc oxide: Two types of zinc oxide manufactured by Hakusui Tech Stearic acid: Tsubaki (made by NOF Corporation) Plasticizer: Diana Process NH-70S manufactured by Idemitsu Kosan Co., Ltd. Antioxidant: Nocrac 6C (aromatic secondary amine-based antioxidant) manufactured by Ouchi Shinko Chemical Co., Ltd. Wax: Sannock manufactured by Ouchi Shinko Chemical Co., Ltd.

[0079] [Evaluation method] <Loss tangent measurement> The rubber composition for fenders was press-crosslinked at 140°C for 60 minutes to produce a crosslinked sheet with a thickness of 2 mm. The sheet sample was punched out to produce rectangular test specimens as specified in Japanese Industrial Standard JIS K6394:2007 "Vulcanized rubber and thermoplastic rubber - Determination of dynamic properties - General guidelines." Measurements were then performed using a small testing device specified in the same standard at temperatures between -70°C and 70°C using the tensile method, a forced vibration non-resonance method, to determine the maximum loss tangent (tanδ). <Measurement conditions> Measurement temperature rise rate: 2°C / min Measurement temperature interval: 2℃ Measurement frequency: 10Hz Initial distortion: 1mm Amplitude: 10μm Deformation mode: tension Chuck distance: 20mm Waveform: Sine wave

[0080] <Hardness measurement test> The rubber composition for fenders was press-crosslinked at 140°C for 60 minutes to produce a crosslinked sheet with a thickness of 2 mm. Three of these crosslinked sheets were stacked to form a test piece for hardness measurement, and the Type A durometer hardness was measured in accordance with the measurement method specified in Japanese Industrial Standard JIS K6253-3:2012 "Vulcanized rubber and thermoplastic rubber - Determination of hardness - Part 3: Durometer hardness." The measurement temperature was the standard test temperature (23°C).

[0081] <Tear test> The rubber composition for fenders was press-crosslinked at 140°C for 60 minutes to produce a crosslinked rubber sheet with a thickness of 2 mm. The crosslinked rubber sheet was then punched out to produce crescent-shaped test specimens as specified in Japanese Industrial Standard JIS K6252:2015, "Vulcanized rubber and thermoplastic rubber - Determination of tear strength - Part 1: Method using trouser-shaped, angle-shaped, and crescent-shaped test specimens." The test specimens were then subjected to a tear test as specified in the same standard to determine the tear strength (N / mm). The measurement temperature was the standard test temperature (23°C). Tear strength was evaluated as follows: less than 70 N / mm was "×", 70 N / mm or more to 80 N / mm was "△", 80 N / mm or more to 90 N / mm was "○", and 90 N / mm or more was "◎".

[0082] <Tensile test> The rubber composition for fenders was press-crosslinked at 140°C for 60 minutes to produce a crosslinked rubber sheet measuring 2 mm thick, 200 mm long, and 200 mm wide. Test specimens (dumbbell-shaped No. 3) were prepared from the crosslinked rubber sheet in accordance with JIS K6251:2017, "Vulcanized and thermoplastic rubber - Determination of tensile properties." Tensile tests were then conducted on the prepared test specimens according to the standard to determine the tensile strength (TS) (MPa) and elongation at break (Eb) (%). The measurement temperature was the standard test temperature (23°C). Tensile strength TS was evaluated as "×" for less than 16 MPa, "○" for 16 MPa or more but less than 20 MPa, and "◎" for 20 MPa or more. Elongation at break Eb was evaluated as "×" for less than 350%, "○" for 350% or more but less than 400%, and "◎" for 400% or more.

[0083] <Easy to buckle> A lambda-shaped miniature fender specimen 1 having the end face shape shown in Figure 1 was fabricated using a rubber fender composition. The head 3 constituting the planar impact surface 2, a pair of support legs 4 hanging down from the head 3 while spreading outward in the longitudinal direction, and a mounting flange 5 connected to the lower end of the support legs 4 and projecting outward were integrally formed from the rubber fender composition, and the miniature fender specimen 1 was fabricated by press-crosslinking at 140°C for 120 minutes. The dimensions of each part were: width W1 of head 3: 65 mm; height H: 100 mm; width W2 between the tips of flanges 5: 180 mm; and total length: 200 mm. The prepared fender specimens were subjected to a compression test using a compression testing machine, with a maximum compression amount of 52.5% of height H, at the standard test temperature (23°C), at a speed of 15 mm / min in the height direction, and three compression tests with a three-minute interval in between. The average value of the reaction force according to the compression ratio during the second and third compression tests was calculated, and the compression ratio (%) was plotted on the horizontal axis and the reaction force (KN) on the vertical axis to determine the compression ratio-reaction force characteristics.

[0084] As is clear from the results in Table 1, the compression curves of the fenders obtained from rubber compositions No. 1 to No. 3 for fenders all showed a decrease in reaction force due to buckling deformation, and good rubber properties were obtained. The tear strength also showed a high value of over 80 N / mm.

[0085] Rubber composition No. 4 for fenders has a DBP absorption of 90 cm 3 The compound does not contain carbon black at a concentration of less than 100g / 100g. The fender obtained from rubber composition No. 4 for fenders had high tear strength and other rubber properties were also good, but no buckling deformation was observed in the compression curve.

[0086] Rubber composition No. 5 for fenders contains 70 g or less of carbon black per 100 g of base rubber. Buckling deformation was observed in the compression curve of the fender obtained from rubber composition No. 5 for fenders, and the physical properties were good, but the tear strength was lower than those of rubber compositions No. 1 to No. 3 for fenders.

[0087] Rubber composition No. 6 for fenders has a nitrogen adsorption specific surface area of ​​70m 2 / g or less of carbon black is blended, and the total DBP absorption of the carbon black is 70cm 3 Buckling deformation was observed in the compression curve of the fender obtained from rubber composition No. 6 for fenders, and the physical properties were good, but the tear strength was lower than those of rubber compositions No. 1 to No. 3 for fenders.

[0088] The fenders obtained from rubber compositions No. 5 and No. 6 for fenders showed buckling deformation and were formulated to be durable for use, but it is clear that the fenders obtained from rubber compositions No. 1 to No. 3 for fenders had greater tear strength and were better. [Explanation of symbols]

[0089] 1: Reduced fender test specimen, 2: Impact surface, 3: Head, 4: Support leg, 5: Flange

[0090] A preferred embodiment (1) of the present invention is a rubber composition containing a base rubber including natural rubber and styrene-butadiene rubber, and carbon black, wherein the amount of the carbon black is 70 g or more and 80 g or less per 100 g of the base rubber, and the total DBP (dibutyl phthalate) absorption of the carbon black, expressed as the product of the amount (g) of the carbon black and the DBP absorption, is 70 cm 3 The carbon black has a nitrogen adsorption specific surface area of ​​70 m or less. 2 / g~120m 2 / g, and DBP (dibutyl phthalate) absorption is 90 cm 3 The rubber composition for a fender is characterized by containing carbon black having a molecular weight of 1 / 100g or less.

[0091] In a preferred embodiment (2) of the present invention, the nitrogen adsorption specific surface area of ​​the carbon black is 70 m 2 / g~120m 2 / g, and DBP (dibutyl phthalate) absorption is 90 cm 3In the rubber composition for a fender of aspect (1), the carbon black content is 8% by mass or more and 100% by mass or less.

[0092] In a preferred embodiment (3) of the present invention, the blending amount (g) of the carbon black and the nitrogen adsorption specific surface area (m 2 / g) and the total surface area of ​​the carbon black is 5000 m 2 The rubber composition for a fender according to the above aspect (1) or (2) is as follows.

[0093] A preferred embodiment (4) of the present invention is the rubber composition for a fender according to any one of the embodiments (1) to (3), further comprising oil and a crosslinking agent.

[0094] A preferred embodiment (5) of the present invention is a cross-linked product of the rubber composition for a fender according to any one of the embodiments (1) to (4), characterized in that the maximum value of loss tangent in the temperature range of -70°C to 70°C, determined by the measurement method specified in Japanese Industrial Standard JIS K6394:2007, is less than 0.480.

[0095] A preferred embodiment (6) of the present invention is a fender having a head portion having an impact surface against which a ship or the like comes alongside, and a support leg portion for supporting the head portion, wherein the support leg portion contains a cross-linked product of the rubber composition for a fender of embodiment (5).

[0096] A preferred embodiment (7) of the present invention is the fender of embodiment (6) formed in an arch shape.

Claims

1. a base rubber containing natural rubber and styrene-butadiene rubber; Carbon black is contained, The amount of carbon black blended is 70 g or more and 80 g or less per 100 g of the base rubber, and the total DBP (dibutyl phthalate) absorption of the carbon black, which is expressed as the product of the amount of carbon black blended (g) and the DBP absorption, is 70 cm ３ is as follows: The carbon black has a nitrogen adsorption specific surface area of ​​70 m ２ / g~120m ２ / g, and DBP (dibutyl phthalate) absorption is 90 cm ３ 1. A rubber composition for a fender, comprising carbon black having a viscosity of 100 g / 100 g or less.

2. The nitrogen adsorption specific surface area of ​​the entire carbon black is 70m ２ / g~120m ２ / g, and DBP (dibutyl phthalate) absorption is 90 cm ３ 2. The rubber composition for a fender according to claim 1, wherein the carbon black content is 8% by mass or more and 100% by mass or less.

3. The amount of carbon black (g) and the nitrogen adsorption specific surface area (m ２ / g) and the total surface area of ​​the carbon black is 5000 m ２ The rubber composition for a fender according to claim 1, wherein the rubber composition is selected from the group consisting of hydroxyapatite, ...

4. The rubber composition for a fender according to claim 1, further comprising an oil and a crosslinking agent.

5. A cross-linked product of the rubber composition for a fender according to any one of claims 1 to 4, characterized in that the maximum value of loss tangent in the temperature range of -70°C to 70°C obtained by the measurement method specified in Japanese Industrial Standards JIS K6394:2007 is less than 0.

480.

6. A fender comprising: a head portion having an impact surface against which a ship or the like comes alongside; and a support leg portion supporting the head portion, wherein the support leg portion contains a cross-linked product of the rubber composition for a fender according to claim 5.

7. 7. The fender according to claim 6, which is formed in an arch shape.

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