Cardanol-based resin and preparation method therefor

Abstract

The present invention provides a cardanol-based resin comprising a copolymer that comprises cardanol and styrene.

Description

Cardanol-based resin and method for manufacturing the same

[0001] The present invention relates to a cardanol-based resin and a method for manufacturing the same. More specifically, the present invention relates to a cardanol-based resin added to a rubber composition for an eco-friendly tire tread and a method for manufacturing the same.

[0002]

[0003] Research is continuing to improve the energy efficiency of tires through fuel efficiency improvements in terms of eco-friendliness.

[0004] When measuring the energy efficiency of a tire by measuring its rolling resistance (RR) and wet grip, which affect fuel efficiency, it is important to improve both simultaneously because rolling resistance and wet grip have a trade-off relationship. Additionally, electric vehicle tires wear out more than 20% faster than standard tires due to the increased load caused by the battery, so electric vehicle tires must possess a higher level of wear resistance and durability.

[0005] Meanwhile, rubber compositions for tire treads consist of raw rubber, fillers, and other additives, and physical properties can be determined by changing the type of raw material or altering the composition. To improve fuel efficiency, the development of tire rubber compositions that possess rolling resistance, road braking performance, and wear resistance through an appropriate balance of physical properties is ongoing.

[0006] Process oil added to tire rubber compositions improves mixing loads when mixing rubber and various additives, reduces compounding energy loss of tire rubber compositions as a softener, and is used to improve compatibility between rubber and various materials used in the rubber composition, such as chemicals and fillers. It is also added to improve compatibility with rubber, the dispersibility of silica, and workability, and paraffinic, naphthenic, and aromatic oils obtained mainly from high-boiling point fractions of petroleum are used.

[0007] Initially, distillate aromatic extract (DAE) was mainly used as process oil, but due to the disadvantage of containing an excessive amount of polycyclic aromatic hydrocarbons (PAHs), which are environmentally regulated substances, the use of treated distillate aromatic extract (TDAE) oil is increasing. However, improvements are still needed in terms of carbon dioxide reduction.

[0008] Therefore, there is an urgent need to develop rubber compositions for tires that are more environmentally friendly and not only improve fuel efficiency, by replacing aromatic process oils, which are hazardous substances among process oils.

[0009] Prior art for the present invention is Korean Published Patent Application No. 10-2012-0077096.

[0010]

[0011] The objective of the present invention is to provide an eco-friendly cardanol-based resin that can replace the conventional process oil added to the rubber composition for tire treads.

[0012] Another objective of the present invention is to provide a method for manufacturing the above-mentioned eco-friendly cardanol-based resin.

[0013] Another objective of the present invention is to provide a rubber composition for tire treads comprising a cardanol-based resin.

[0014] The above and other objectives of the present invention can all be achieved by the present invention described below.

[0015]

[0016] 1. One aspect of the present invention relates to an eco-friendly cardanol-based resin.

[0017] The above cardanol-based resin includes a copolymer comprising cardanol and styrene.

[0018] 2. In the above 1 embodiment, the copolymer may comprise a cardanol content of 30% to 70% by weight; and a styrene content of 30% to 70% by weight.

[0019] 3. In the above 1 or 2 embodiments, the cardanol-based resin may have an aromatization degree of 22% to 43%.

[0020] 4. In any one of the embodiments 1 to 3 above, the cardanol-based resin may have a weight-average molecular weight (Mw) of 900 to 2000, a number-average molecular weight (Mn) of 600 to 900, and a molecular weight distribution (PDI) of 1.5 to 2.5.

[0021] 5. In any one of the embodiments 1 to 4 above, the cardanol-based resin may have a carbon emission of 2.3 kg CO2 / kg or less.

[0022] 6. Another aspect of the present invention relates to a method for manufacturing a cardanol-based resin.

[0023] The above method for manufacturing a cardanol-based resin comprises: (a) a step of preparing a monomer composition comprising a cardanol monomer, a styrene monomer, and a xylene solvent;

[0024] (b) a step of preparing a reaction product by primary polymerizing the above monomer composition;

[0025] (c) a step of preparing a polymer by secondary polymerizing the above reaction product; and

[0026] (d) a step of recovering the cardanol-based resin by reducing the pressure of the polymer; is included.

[0027] 7. In the above 6 embodiments, the primary polymerization may be carried out in a continuous stirred tank reactor (CSTR), and the secondary polymerization may be carried out in a plug flow reactor (PFR) placed downstream of the continuous stirred tank reactor.

[0028] 8. In the above 6 or 7 embodiments, the secondary polymerization temperature may be higher than the primary polymerization temperature.

[0029] 9. In any one of the embodiments 6 to 8 above, the volume of the plug flow reactor (PFR) may be larger than the volume of the continuous stirred tank reactor (CSTR).

[0030] 10. Another aspect of the present invention relates to a process oil of a rubber composition for a tire tread.

[0031] The above process oil comprises a cardanol-styrene copolymer having a weight-average molecular weight (Mw) of 900 to 2000, a number-average molecular weight (Mn) of 600 to 900, and a molecular weight distribution (PDI) of 1.5 to 2.5.

[0032] 11. In the above 9 embodiments, the process oil may have a degree of aromaticity of 22% to 43%.

[0033] 12. Another aspect of the present invention is a rubber composition for a tire tread comprising the above-mentioned cardanol-based resin.

[0034] 13. In the above 12 embodiments, the rubber composition for the tire tread may contain 10 to 50 parts by weight of cardanol resin per 100 parts by weight of raw rubber.

[0035] 14. In the above 12 or 13 embodiments, the rubber composition for the tire tread may have a loss factor (tanδ) of 100 to 110 according to the measurement of wet road braking force (0°C) at a temperature range of -80 to 110°C and 10 Hz according to dynamic mechanical analysis, and a loss factor (tanδ) of 70 to 95 according to the measurement of rolling resistance (60°C).

[0036] 15. In any one of the embodiments of 12 to 14 above, the rubber composition for the tire tread may have a wear degree of 70 to 95 as measured by a wear degree measuring instrument.

[0037]

[0038] The cardanol-based resin according to the present invention is highly environmentally friendly because it does not contain polycyclic aromatic hydrocarbons (PAHs), which are aromatic components harmful to the environment, and can replace process oils added to rubber compositions for tire treads.

[0039] Tires manufactured using a rubber composition blended with cardanol-based resin exhibit improved rolling resistance and road braking performance, demonstrating effects equivalent to or greater than those of conventional process oils such as TDAE. In particular, the rubber composition blended with cardanol-based resin is highly suitable for electric vehicles due to its significantly improved wear resistance.

[0040] In addition, eco-friendly cardanol resins are very effective in reducing greenhouse gas emissions because they have the effect of reducing carbon emissions to 2.3 kg CO2 / kg or less.

[0041]

[0042] FIG. 1 is a process flowchart of a method for manufacturing a cardanol-based resin according to one embodiment of the present invention.

[0043] FIG. 2 is a graph comparing the wet grip, rolling resistance, and wear of a rubber specimen prepared using a cardanol resin prepared according to a method for preparing a cardanol resin according to one embodiment of the present invention as a process oil, and a rubber specimen prepared using a process oil of an aromatic component resin.

[0044] FIG. 3 shows the amount of carbon emissions generated during the manufacturing process of a cardanol-based resin according to one embodiment of the present invention.

[0045]

[0046] The present invention will be described in more detail below with reference to the attached drawings. However, the following drawings are provided merely to aid in understanding the present invention, and the present invention is not limited by the drawings. Furthermore, the shapes, sizes, ratios, angles, numbers, etc. disclosed in the drawings are exemplary, and the present invention is not limited to the depicted details.

[0047] Throughout the specification, the same reference numerals refer to the same components. Additionally, in describing the present invention, detailed descriptions of related prior art are omitted if it is determined that such detailed descriptions would unnecessarily obscure the essence of the invention.

[0048] Where terms such as 'includes,' 'have,' and 'consists of' are used in this specification, other parts may be added unless 'only' is used. Where a component is expressed in the singular, it includes cases where it includes the plural unless specifically stated otherwise.

[0049] In interpreting the components, they are interpreted to include a margin of error even in the absence of a separate explicit statement.

[0050] In this specification, "a to b" indicating a numerical range is defined as "≥a and ≤b".

[0051] In this specification, all numerical ranges include a 95% standard error range.

[0052] One aspect of the present invention relates to a cardanol-based resin.

[0053] The above cardanol-based resin includes a copolymer comprising cardanol and styrene.

[0054] Specifically, the above cardanol-based resin comprises a copolymer containing 30% to 70% by weight of cardanol and 30% to 70% by weight of styrene.

[0055] The above cardanol-based resin can be prepared by polymerizing a cardanol monomer and a styrene monomer, and the cardanol monomer can be represented by the following chemical formula 1 using vegetable oil.

[0056] [Chemical Formula 1]

[0057]

[0058] The above cardanol monomer is an eco-friendly material because it is a vegetable oil obtained by naturally extracting cashew nuts from tropical rainforests, and it can reduce manufacturing costs.

[0059] The above cardanol monomer can be copolymerized with a styrene monomer to form a copolymer, and when copolymerized with the above styrene monomer, the hydroxyl group of cardanol is substituted, which has the advantage of removing toxicity and preventing VOC generation.

[0060] The copolymer composed of the above cardanol monomer and styrene monomer can replace DAE or TDAE, which are process oils that are essential in the manufacture of rubber compositions for conventional tire treads.

[0061] The chemical formula of the above styrene monomer is C8H8, and it has a structure in which one hydrogen atom in the benzene ring is substituted with a vinyl group. The above styrene may be produced by dehydrogenation of ethylbenzene using a catalyst such as zinc, iron, chromium, calcium, or magnesium.

[0062] The above styrene can be represented by the following chemical formula 2.

[0063] [Chemical Formula 2]

[0064]

[0065] Since the above styrene has vinyl groups, it is easily polymerized by heat, peroxides, supercatalysts, etc. to become a polymer compound.

[0066] A copolymer is produced by copolymerizing the above cardanol monomer and the above styrene monomer, and the cardanol-based resin containing the same can exclude aromatic components from tire tread process oil and can be utilized as an environmentally friendly process oil.

[0067] The copolymer may contain 30% to 70% by weight of cardanol and 30% to 70% by weight of styrene. A copolymer is produced by copolymerizing within the above range, and a cardanol-based resin containing the same can replace the process oil in a rubber composition for tire treads.

[0068] In one embodiment, the cardanol-based resin may have an aromatization degree of 22% to 43%. When having an aromatization degree within the above range, it can not only replace process oils of aromatic components but also improve wet grip and abrasion resistance compared to TDAE.

[0069] The above cardanol petroleum resin may have a weight-average molecular weight (Mw) of 900 to 2000, preferably 980 to 1912, a number-average molecular weight (Mn) of 600 to 900, preferably 670 to 860, and a molecular weight distribution (PDI) of 1.5 to 2.5, preferably 1.55 to 2.4. When having a weight-average molecular weight, a number-average molecular weight, and a molecular weight distribution within the above ranges, it can be used as a process oil for tire treads to improve the rolling resistance and road braking power of the tire, thereby realizing the effects of the present invention, as well as improving the wear resistance of the tire.

[0070] Another aspect of the present invention relates to a method for manufacturing a cardanol-based resin.

[0071] FIG. 1 is a process flowchart of a method for manufacturing cardanol petroleum resin according to one embodiment of the present invention.

[0072] Referring to FIG. 1, the method for manufacturing a cardanol-based resin comprises: (a) a step of preparing a monomer composition comprising a cardanol monomer, a styrene monomer, and a xylene solvent;

[0073] (b) a step of preparing a reaction product by primary polymerizing the above monomer composition;

[0074] (c) a step of preparing a polymer by secondary polymerizing the above reaction product; and

[0075] (d) a step of recovering the cardanol-based resin by reducing the pressure of the polymer; is included.

[0076] First, a monomer composition comprising a cardanol monomer, a styrene monomer, and a xylene solvent is prepared (S100).

[0077] For example, 25 parts by weight of xylene solvent may be mixed with 100 parts by weight of raw materials including cardanol monomers, styrene monomers, and combinations thereof, and the raw materials may contain 30% to 70% by weight of cardanol, preferably 65% ​​to 70% by weight, and 30% to 70% by weight of styrene, preferably 20% to 35% by weight.

[0078] A copolymer can be prepared by copolymerizing a cardanol monomer and a styrene monomer within the above range, and the effects of the present invention can be realized by using the prepared copolymer as a process oil for a rubber composition for tire treads.

[0079] When polymerizing within the above range, a copolymer that implements the effects of the present invention can be produced by controlling the degree of aromatization (Aromaticity), weight-average molecular weight (Mw), number-average molecular weight (Mn), and molecular weight distribution (PDI).

[0080] The above monomer composition is polymerized first to produce a reaction product (S200).

[0081] Specifically, a reaction product can be produced by continuously supplying a monomer composition to a continuous stirred tank reactor (CSTR) and polymerizing it in one step.

[0082] The above-described continuous stirred tank reactor can continuously polymerize a monomer composition to produce a reaction product, and can effectively improve polymerization efficiency by vigorously stirring the cardanol monomer and styrene monomer. It also has the advantages of being easy to maintain the target temperature during polymerization and suppressing scale formation within the reactor.

[0083] In the above S200, the first stage polymerization can be carried out for 40 to 50 minutes under conditions of 260°C to 280°C and 23 to 27 bar. The above first stage polymerization can be carried out continuously in a continuous stirred tank reactor, and a reaction product can be produced with a high conversion rate under these conditions.

[0084] A polymer is prepared by secondary polymerization of the above reaction product (S300).

[0085] Specifically, the reaction product can be introduced into a plug flow reactor (PFR) located downstream of the continuous stirred tank reactor and polymerized in two stages to produce a polymer.

[0086] A plug flow reactor can be placed after the above-mentioned continuous stirred tank reactor to enable continuous polymerization.

[0087] The plug flow reactor described above is highly desirable because it discharges reaction products in an amount equal to the amount introduced from the continuous stirred tank reactor, enables uniform molecular weight control, and offers excellent production yield.

[0088] When a plug flow reactor is placed downstream of the above-mentioned continuous stirred tank reactor, the polymer can be manufactured with high efficiency compared to cases where other reactors are placed, and the effects of the present invention can be realized.

[0089] In the above secondary polymerization, the cardanol monomer and the styrene monomer can be copolymerized to produce a cardanol-styrene copolymer.

[0090] In the above S300, secondary polymerization can be carried out for 60 to 80 minutes under conditions of 270°C to 290°C and 23 to 27 bar. When polymerizing within the above range, the cardanol monomer and the styrene polymer are copolymerized, and a copolymer can be produced with a high conversion rate.

[0091] In one embodiment, the secondary polymerization temperature may be higher than the primary polymerization temperature. When the secondary polymerization temperature is high, reactivity is improved, allowing the polymer conversion rate in the plug flow reactor to be maintained at a high level.

[0092] In one embodiment, the volume of the plug flow reactor (PFR) may be larger than the volume of the continuous stirred tank reactor (CSTR). When the volume of the plug flow reactor is larger than the volume of the continuous stirred tank reactor, the polymerization rate can be effectively controlled during continuous polymerization to produce a cardanol-styrene copolymer.

[0093] In one embodiment, polymerization efficiency can be maximized by placing a plug flow reactor (PFR) downstream of the continuous stirred tank reactor (CSTR).

[0094] By configuring a polymerization system in which the above-mentioned continuous stirred tank reactor is placed in the current phase and a plug flow reactor is placed in the downstream phase, not only the polymerization efficiency but also the conversion rate can be increased.

[0095] The above polymer is reduced in pressure to recover the cardanol-based resin (S400).

[0096] Specifically, the polymer can be recovered by reducing the pressure in the plug flow reactor at a temperature of 250°C to 270°C for 20 to 40 minutes.

[0097] A cardanol-styrene copolymer is produced in the above plug flow reactor, and subsequently, the cardanol-styrene copolymer can be recovered by depressurizing the reactor to remove the residual solvent.

[0098] The cardanol-based resin containing the above cardanol-styrene copolymer does not contain aromatic components and can be used as an eco-friendly additive in rubber compositions for tire treads, specifically, it can replace process oil.

[0099] Using the above cardanol-based resin as a process oil is very environmentally friendly.

[0100] Cardanol is typically widely used as fuel for power plants, but when used as a process oil, it can be utilized in a more environmentally friendly manner and effectively reduce carbon emissions. Furthermore, using the aforementioned cardanol petroleum resin as a process oil can improve tire rolling resistance, road braking performance, and wear resistance, and can exhibit properties equivalent to or better than those of conventional TDAE.

[0101] The above-mentioned pressure can be applied to the product at a temperature range of 130°C to 170°C for 20 to 30 minutes. For example, it can be applied at 150°C for 30 minutes. When the pressure is applied within the above range, the cardanol-based resin can be recovered very effectively.

[0102] The cardanol-based resin produced by the above-described method for manufacturing cardanol-based resin can replace the process oil used in rubber compositions for tire treads.

[0103] The above cardanol-based resin can reduce carbon emissions during the manufacturing process to 2.3 kg CO2 / kg or less and is very environmentally friendly.

[0104] Another aspect of the present invention provides a process oil for tire treads.

[0105] The above process oil for tire treads may include a cardanol-styrene copolymer having a weight-average molecular weight of 900 to 2000, a number-average molecular weight (Mn) of 600 to 900, and a molecular weight distribution (PDI) of 1.5 to 2.5.

[0106] In one embodiment, the process oil may have a degree of aromatization of 22% to 43%.

[0107] The degree of aromaticity of the above process oil can improve compatibility with polymers within the above range. Specifically, since the aromatic content of rubbers mainly used in tires is around 15% and the aromatic content in the overall tire compound is around 12%, the process oil can exhibit excellent compatibility with rubber and tire compounds in terms of aromatic content within the above range.

[0108] Another aspect of the present invention relates to a rubber composition for a tire tread comprising the cardanol-based resin as a process oil.

[0109] The above rubber composition for tire treads comprises raw rubber and the cardanol-based resin, and accordingly exhibits high road braking performance and fuel efficiency.

[0110] The above cardanol-based resin is included in the rubber composition for tire treads to further improve the adhesive performance between rubbers, and improves the miscibility, dispersibility, and processability of fillers and other additives, thereby improving the physical properties of the rubber composition for tire treads.

[0111] In particular, the above cardanol-based resin satisfies the monomer composition and degree of aromatization described above, thereby exhibiting excellent compatibility with raw rubber and additives, and can minimize the increase in rolling resistance while providing improved braking performance due to excellent adhesion.

[0112] The above raw rubber is not particularly limited as long as it has an olefinic double bond (carbon-carbon double bond), and natural rubber, synthetic rubber, or a mixture thereof may be used.

[0113] For example, the above raw rubber may be one or more selected from the group consisting of natural rubber, butadiene rubber, nitrile rubber, silicone rubber, isoprene rubber, styrene-butadiene rubber (SBR), isoprene-butadiene rubber, styrene-isoprene-butadiene rubber, acrylonitrile-butadiene rubber (NBR), ethylene-propylene-diene rubber, butyl halogenated rubber, isoprene halogenated rubber, isobutylene copolymer, chloroprene rubber, butyl rubber, and isobutylene-p-methylstyrene halogenated rubber.

[0114] The above cardanol-based resin can exhibit compatibility with the above type of raw rubber.

[0115] In one embodiment, the rubber composition for a tire tread may contain 10 to 50 parts by weight of the cardanol petroleum resin with respect to 100 parts by weight of raw rubber. Preferably, it may contain 20 to 50 parts by weight, and more preferably 20 to 30 parts by weight.

[0116] If the content of the above cardanol petroleum resin is less than 10 parts by weight per 100 parts by weight of raw rubber, it is difficult to secure dispersibility, processability, and braking characteristics, and if it exceeds 50 parts by weight, although the braking characteristics become excellent, there may be a problem where the rolling resistance becomes too high. Within the above range, road surface braking and rolling resistance, which are in a trade-off relationship, can be optimally controlled.

[0117] The above rubber composition for tire treads may further include one or more selected from the group consisting of fillers, silane coupling agents, anti-aging agents, softeners, vulcanizing agents, vulcanization accelerators, and vulcanization accelerating aids.

[0118] The above filler is added to increase the durability and heat resistance of the tire and to improve chipping resistance, cutting resistance, and wear resistance, and, for example, carbon black and / or silica may be used.

[0119] The above carbon black has a nitrogen adsorption specific surface area per gram (N2SA) of 30 to 300 m² 2 It can be / g, and the DBP (n-dibutyl phthalate) oil absorption amount can be 60 to 180 cc / 100g.

[0120] The nitrogen adsorption specific surface area of ​​the above carbon black is 300 m² 2 If it exceeds / g, the processability of the rubber composition for tires may become unfavorable, and 30 m 2 If it is less than / g, the reinforcing performance by the carbon black filler may be disadvantageous. In addition, if the DBP oil absorption amount of the carbon black exceeds 180cc / 100g, the processability of the rubber composition may be reduced, and if it is less than 60cc / 100g, the reinforcing performance by the carbon black filler may be disadvantageous.

[0121] The carbon black may be included in an amount of 1 to 50 parts by weight, preferably 5 to 30 parts by weight, per 100 parts by weight of the raw rubber. If the content of the carbon black is less than 1 part by weight, the reinforcing performance by the carbon black filler may be reduced, and if it exceeds 50 parts by weight, the processability of the rubber composition may become unfavorable.

[0122] The above silica has a nitrogen adsorption specific surface area per gram of 100 to 180 m² 2 / g, and the specific surface area for CTAB (cetyl trimethyl ammonium bromide) adsorption is 110 to 170 m² 2 It may be / g, but the present invention is not limited thereto.

[0123] The nitrogen adsorption specific surface area of ​​the above silica is 100 m² 2 If it is less than / g, the reinforcing performance by the silica filler may be unfavorable, and 180 m 2 If it exceeds / g, the processability of the rubber composition may be adverse. In addition, the CTAB adsorption specific surface area of ​​the silica is 110 m² 2 If it is less than / g, the reinforcing performance by the silica filler may be unfavorable, and 170 m 2 If it exceeds / g, the processability of the rubber composition may be adverse.

[0124] The silica may be included in an amount of 10 to 150 parts by weight per 100 parts by weight of the raw rubber, and preferably in an amount of 50 to 100 parts by weight. If the silica content is less than 10 parts by weight, the improvement in the strength of the rubber is insufficient and the fuel efficiency of the tire may be reduced, and if the silica content exceeds 150 parts by weight, the wear performance may be reduced.

[0125] Meanwhile, when using the above silica, a silane coupling agent may be further included for the formulation of the silica. The above silane coupling agents include vinyltrichlorosilane, vinyltriethoxysilane, vinyltris(β-methoxy-ethoxy)silane, β-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, bis(3-(triethoxysilyl)propyl)disulfide, bis(3-triethoxysilylpropyl)trisulfide, bis(3-(triethoxysilyl)propyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-Mercaptopropyltriethoxysilane, 2-Mercaptoethyltrimethoxysilane, 2-Mercaptoethyltriethoxysilane, 3-Trimethoxysilylpropyl-N,N-Dimethylthiocarbamoyltetrasulfide, 3-Triethoxysilylpropyl-N,N-Dimethylthiocarbamoyltetrasulfide, 2-Triethoxysilylethyl-N,N-Dimethylthiocarbamoyltetrasulfide, 3-Trimethoxysilylpropylbenzothiazolyltetrasulfide, 3-Triethoxysilylpropylbenzolyltetrasulfide, 3-Triethoxysilylpropylmethacrylate monosulfide, 3-Trimethoxysilylpropylmethacrylate monosulfide, Bis(3-diethoxymethylsilylpropyl)tetrasulfide, 3-Mercaptopropyldimethoxymethylsilane, Examples include dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide and dimethoxymethylsilylpropylbenzothiazolyltetrasulfide, which are used alone or in a mixture of two or more types, and preferably bis(3-(triethoxysilyl)propyl)tetrasulfide can be used.

[0126] The above silane coupling agent may be included in an amount of 1 to 15 parts by weight or 5 to 10 parts by weight per 100 parts by weight of the raw rubber to improve the dispersibility of the silica. If the content of the silane coupling agent is less than 1 part by weight, the improvement in the dispersibility of the silica is insufficient, which may result in reduced processability of the rubber or reduced fuel efficiency. If it exceeds 20 parts by weight, the interaction between the silica and the rubber is too strong, which may result in excellent fuel efficiency but significantly reduced braking performance.

[0127] The above anti-aging agent is an additive used to stop the chain reaction in which the tire is auto-oxidized by oxygen. As the above anti-aging agent, any one selected from the group consisting of amine-based, phenol-based, quinoline-based, imidazole-based, metal carbamate salts, waxes, and combinations thereof may be appropriately selected and used.

[0128] As the above amine-based anti-aging agent, any one selected from the group consisting of N-phenyl-N'-(1,3-dimethyl)-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, N,N'-diaryl-p-phenylenediamine, N-phenyl-N'-cyclohexyl p-phenylenediamine, N-phenyl-N'-octyl-p-phenylenediamine, and combinations thereof may be used. As the above phenol-based anti-aging agent, any one selected from the group consisting of phenolic 2,2'-methylene-bis(4-methyl-6-tert-butylphenol), 2,2'-isobutylidene-bis(4,6-dimethylphenol), 2,6-di-t-butyl-p-cresol, and combinations thereof may be used. As the above-mentioned quinoline-based anti-aging agent, 2,2,4-trimethyl-1,2-dihydroquinoline and derivatives thereof may be used, specifically, any one selected from the group consisting of 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, 6-anilino-2,2,4-trimethyl-1,2-dihydroquinoline, 6-dodecyl-2,2,4-trimethyl-1,2-dihydroquinoline, and combinations thereof may be used. Preferably, waxy hydrocarbon may be used as the above-mentioned wax.

[0129] Considering conditions such as having high solubility in rubber, low volatility, being inert to rubber, and not inhibiting vulcanization in addition to anti-aging action, the above anti-aging agent may be included in an amount of 1 to 10 parts by weight per 100 parts by weight of the raw rubber.

[0130] The above-mentioned softener is added to impart plasticity to the rubber to facilitate processing, or to reduce the hardness of vulcanized rubber, and may use petroleum-based oils, vegetable oils, and combinations thereof. Specifically, as a softener, TDAE (treated distillate aromatic extracts) oil, MES (mild extraction solvate) oil, RAE (residual aromatic extract) oil, or heavy naphthenic oil may be used, and preferably, TDAE oil may be used.

[0131] It is preferable to use the above softening agent in an amount of 1 to 20 parts by weight per 100 parts by weight of the raw rubber in terms of processability.

[0132] As the above vulcanizing agent, a sulfur-based vulcanizing agent may be preferably used. As the above sulfur-based vulcanizing agent, inorganic vulcanizing agents such as powdered sulfur (S), insoluble sulfur (S), precipitated sulfur (S), and colloidal sulfur may be used. Specifically, as the above sulfur-based vulcanizing agent, elemental sulfur or a vulcanizing agent that produces sulfur, such as amine disulfide or polymeric sulfur, may be used.

[0133] It is desirable for the above vulcanizing agent to be included in an amount of 0.5 parts by weight or more, or 1.0 parts by weight or more, and 4.0 parts by weight or less, or 3.0 parts by weight or less, per 100 parts by weight of the above raw rubber, in terms of securing an appropriate vulcanization effect and stability of the raw rubber.

[0134] The above vulcanization accelerator is an accelerator that accelerates the vulcanization rate or promotes a delaying effect during the initial vulcanization stage.

[0135] Examples of the above vulcanization promoters include thiuram-based promoters such as trimethylthiuram monosulfide, tetramethylthiuram disulfide, and tetraethylthiuram disulfide; thiazole-based promoters such as 2-mercaptobenzothiazole and dibenzothiazyl disulfide; sulfenamide-based promoters such as N-cyclohexyl-2-benzothiazylsulfenamide and N-oxydiethylene-2-benzothiazolylsulfenamide; aldehyde-amine-based promoters such as n-butylaldehyde-aniline condensation products and butylaldehyde-monobutylamine condensation products; aldehyde-ammonia-based promoters such as hexamethylenetetramine; thiourea-based promoters such as thiocarbanilide; and guanidine-based promoters such as 1,3-diphenylguanidine. When formulating these vulcanization accelerators, one type may be used alone or two or more types may be used in combination. For example, 1,3-diphenylguanidine (DPG) and N-cyclohexyl-2-benzothiazylsulfenamide (CBTS) may be used as vulcanization accelerators.

[0136] It is preferable to use the above vulcanization accelerator in an amount of 0.1 to 10 parts by weight per 100 parts by weight of raw rubber in terms of improving physical properties.

[0137] The above vulcanization accelerating agent is used in combination with the above vulcanization accelerator to further enhance the accelerating effect.

[0138] Examples of the above vulcanization accelerating agents include metal oxides such as zinc oxide and magnesium oxide, metal hydroxides such as calcium hydroxide, metal carbonates such as zinc carbonate and basic zinc carbonate, fatty acids such as stearic acid and oleic acid, aliphatic metal salts such as zinc stearate and magnesium stearate, amines such as n-butylamine and dicyclohexylamine, ethylene dimethacrylate, diallyl phthalate, N,Nm-phenylenedimaleimide, trialyl isocyanurate, and trimethylolpropane trimethacrylate. When these vulcanization agents are used, one type may be used alone, or two or more types may be used in combination.

[0139] It is preferable to use the above vulcanization accelerating agent in an amount of 0.1 to 10 parts by weight per 100 parts by weight of raw rubber in terms of improving physical properties.

[0140] Meanwhile, the above rubber composition for tire treads may further include various additives used in the rubber industry, such as vulcanization retardants, release agents, process oils, plasticizers, etc.

[0141] The above rubber composition for tire treads can be prepared by mixing each of the above-described components using a mixing machine such as a plastomill, a Banbury mixer, a roll, or an internal mixer.

[0142] The rubber composition for a tire tread manufactured by the above method can be used as a material for constituting the tread portion (and the cap portion including the tread portion) that contacts the road surface, and furthermore, can be used for various rubber components constituting the tire, such as the sidewall, sidewall insert, apex, chafer, wire coat, or inner liner.

[0143] A tire manufactured using the above rubber composition for tire treads has high grip, excellent driving stability and braking performance, and low rolling resistance, making it suitable for use as a fuel-efficient and high-performance tire.

[0144] In one embodiment, the rubber composition for the tire may have a loss factor (tanδ) of 100 to 110 according to the dynamic mechanical analysis method for measuring wet grip at a temperature range of -80 to 110°C and 10 Hz (0°C), and a loss factor (tanδ) according to the rolling resistance measurement (60°C) of 70 to 95. When the loss factor (tanδ) when measuring wet grip at 0°C and the loss factor (tanδ) when measuring tire rolling resistance at 60°C are adjusted within the above range according to the dynamic mechanical analysis measurement, optimal wet grip and tire rolling resistance are exhibited, and wet grip and rolling resistance equivalent to or greater than that of conventional TDAE are exhibited, thereby realizing the effects of the present invention.

[0145] In one embodiment, the rubber composition for the tire tread may have a wear level of 90 to 120 as measured by a wear level measuring instrument.

[0146] Specifically, the above abrasion level is expressed as the reciprocal of the wear loss after measuring the wear loss according to the following mathematical formula 2 using an abrasion tester (Abrasion Tester (Heinrich Bareiss Prufgeratebau GmbH)).

[0147] [Mathematical Formula 2]

[0148] (Mass before wear) / (Mass after wear) = Wear loss

[0149] The above wear value is expressed as the reciprocal of wear loss to facilitate performance verification; the higher the wear value, the less wear loss and the better the wear resistance.

[0150] The above rubber composition for tires exhibits significantly improved wear resistance, possessing higher wear resistance compared to conventional rubber compositions using TDAE as a process oil, and is highly suitable as a rubber composition for electric vehicle tires.

[0151] In one embodiment, the rubber composition for tires may have a carbon emission of 2.3 kg CO2 / kg or less.

[0152] The above-mentioned rubber composition for tires uses cardanol petroleum resin as a process oil, can reduce carbon emissions beyond a certain limit, and is highly environmentally friendly compared to DAE and TDAE, which are conventionally used as process oils.

[0153]

[0154] Hereinafter, the structure and operation of the present invention will be explained in more detail through preferred embodiments of the present invention. However, the following embodiments are intended to aid in understanding the present invention, and the scope of the present invention is not limited to the following embodiments.

[0155]

[0156] Example 1

[0157] A monomer composition was prepared by mixing 840g of cardanol monomer (80% purity) and 1960g of styrene monomer in 700g of xylene solvent.

[0158] While continuously supplying the above monomer composition to a continuous stirred tank reactor (hereinafter 'CSTR', internal volume: 0.416 L), a first-stage polymerization was carried out for 42 minutes under conditions of a temperature of 270°C and a pressure of 25 bar.

[0159] While continuously feeding the reaction product from the first stage polymerization into a plug flow reactor (hereinafter 'PFR', internal volume: 0.590 L) connected to the CSTR, a second stage polymerization was carried out for 64 minutes under conditions of a temperature of 280°C and a pressure of 25 bar.

[0160] The polymerization-completed product was subjected to reduced pressure at 260°C for 30 minutes to recover a cardanol-based resin containing a cardanol-styrene copolymer.

[0161]

[0162] Example 2

[0163] A monomer composition was prepared by mixing 1120g of cardanol monomer and 1690g of styrene monomer, and a cardanol-based resin was prepared by polymerizing it in the same manner as in Example 1.

[0164]

[0165] Example 3

[0166] A monomer composition was prepared by mixing 1400g of cardanol monomer and 1400g of styrene monomer, and a cardanol-based resin was prepared by polymerizing it in the same manner as in Example 1.

[0167]

[0168] Example 4

[0169] A monomer composition was prepared by mixing 1680g of cardanol monomer and 1120g of styrene monomer, and a cardanol-based resin was prepared by polymerizing it in the same manner as in Example 1.

[0170]

[0171] Example 5

[0172] A monomer composition was prepared by mixing 1960g of cardanol monomer and 840g of styrene monomer, and a cardanol-based resin was prepared by polymerizing it in the same manner as in Example 1.

[0173]

[0174] Comparative Example 1

[0175] TDAE_STD, which is used as a process oil for tire rubber compositions, was prepared.

[0176]

[0177] Comparative Example 2

[0178] Cardanol that was not copolymerized with styrene was prepared as a process oil.

[0179]

[0180] Experimental Example 1

[0181] The degree of aromatization was measured for the cardanol-based resins prepared in Examples 1 to 5 and Comparative Examples 1 and 2.

[0182] The weight-average molecular weight (Mw), number-average molecular weight (Mn), and average molecular weight (Mz) of polystyrene were determined through gel permeation chromatography (GPC; Infinity1260) analysis. Additionally, PDI (Mw / Mn) was calculated as the ratio of Mn to the measured Mw.

[0183] Specifically, the cardanol-based resin of the example was dissolved in tetrahydrofuran to a concentration of 5 wt%, and 10 µl was injected into the GPC. Tetrahydrofuran was used as the mobile phase of the GPC and introduced at a flow rate of 1 mL / min, and the analysis was performed at 35°C. The column consisted of one Guard column and three PL gels connected in series: PL gel 5 µm 500A, PL gel 5 µm 100A, and PL gel 5 µm 50A. A refractive index detector (RID) was used as the detector, and measurements were taken at 35°C.

[0184] In the case of Example 1, the weight-average molecular weight (Mw) was confirmed to be 1912, the number-average molecular weight (Mn) to be 859, and the PDI (Mw / Mn) to be 2.23.

[0185] To determine whether the manufactured cardanol petroleum resin could replace the process oil in the rubber composition for tire treads, the degree of aromatization of the manufactured cardanol petroleum resin was measured.

[0186] Aromaticity (%) was determined by dissolving the resin in the solvent CDCl3 at a concentration of 2.5 wt%, performing 1H-NMR analysis (600 MHz), and calculating the aromaticity from the ratio of the number of protons in the aromatic region to the total number of protons in the polymer as shown in Equation 1 below.

[0187] [Mathematical Formula 1]

[0188]

[0189] In the above mathematical formula 1, ArA is the number of protons obtained from the area ratio of hydrogen peaks bonded to aromatic hydrocarbons appearing in the aromatic region, specifically in the 6.0 to 9.0 ppm region; OA is the number of protons obtained from the area ratio of hydrogen peaks appearing in the olefin region, specifically in the 4.0 to 6.0 ppm region; and AlA is the number of protons obtained from the area ratio of hydrogen peaks bonded to aliphatic hydrocarbons appearing in the aliphatic region, specifically in the 0.1 to 4.0 ppm region.

[0190] For Example 1, it was confirmed to be 42.59%, for Example 2 37.61%, for Example 3 32.32%, for Example 4 27.36%, and for Example 5 22.76%.

[0191] Comparative Example 1 was confirmed to be 4.96%, and Comparative Example 2 was 12.54%.

[0192]

[0193] Experimental Example 2

[0194] It was confirmed whether the cardanol-based resin of the example could replace the process oil in the rubber composition for tire treads.

[0195] Compounding was performed to manufacture a rubber composition for tire treads, specifically using 84.60 g of styrene-butadiene rubber (SBR, Kumho Petrochemical 5251H) and 28.20 g of neodymium butadiene rubber (Kumho Petrochemical NdBR40) as raw rubbers, 112.87 g of silica (EVONIK Ultrasil VN3 GR) and 5.64 g of carbon black (OEC N220) as fillers, 11.29 g of bis(3-(triethoxysilyl)propyl)tetrasulfide (TESPT, EVONIK Si-69) as a silane coupling agent, 1.69 g of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) as an anti-aging agent, and 1,3-diphenylguanidine (DPG) as a vulcanization accelerator A rubber composition for a tire tread was prepared by adding 2.11 g of N-cyclohexyl-2-benzothiazylsulfenamide (CBTS) 1.47 g, 3.39 g of ZnO and 2.26 g of stearic acid as vulcanization accelerators, 1.58 g of sulfur as a vulcanizing agent, 19.75 g of TDAE (Treated Distillate Aromatic Extracts) and 1.13 g of wax as softeners, and 22.57 g of petroleum resins of Examples 1 to 5, and compounding in a Brabender mixer.

[0196] Subsequently, test rubber specimens were prepared by vulcanizing at 160°C for about 20 minutes. The vulcanization time was set to the t90 value of the MDR (Moving die rheometer).

[0197] Rubber specimens were prepared using the cardanol petroleum resins of Examples 1 to 5 as process oils, and the petroleum resins of Comparative Example 1 (TDAE) and Comparative Example 2 (cardanol) were used as process oils among the additives.

[0198] [Table 1]

[0199]

[0200]

[0201] Table 1 above shows the reactor temperature conditions and the measurement results of cardanol and styrene content, degree of aromatization, weight-average molecular weight, number-average molecular weight, and molecular weight distribution of the cardanol petroleum resins of Preparation Example and Examples 1 to 5.

[0202] Referring to Table 1 above, it was confirmed that the weight-average molecular weight of the specimens of Examples 1 to 5, in which cardanol-styrene copolymer was used as the process oil, was 980 to 1912, the number-average molecular weight was 634 to 589, and the molecular weight distribution was 1.55 to 2.23.

[0203] It was confirmed that the weight-average molecular weight, number-average molecular weight, and molecular weight distribution changed depending on the content conditions of cardanol and styrene monomers.

[0204] At this time, if the molecular weight is too large, it is difficult to function as a process oil, and if the polymerization temperature is kept low under process conditions, the molecular weight increases due to the styrene monomer, and since the polymerization temperature is low, there is a problem of the overall process yield decreasing. It was confirmed that the molecular weight of each specimen is the result of the process conditions according to the example, and maintaining the weight-average molecular weight at 2000 or less, the number-average molecular weight at 650 or less, and the molecular weight distribution at 1.5 to 2.3 is the optimal condition for commercial production yield.

[0205]

[0206] Experimental Example 3

[0207] The loss factor (Tan δ) related to wet grip and rolling resistance was measured for the manufactured rubber specimens using Dynamic Mechanical Analysis (Model: TA-DMA Q800) at a temperature range of -80 to 80°C and 10 Hz.

[0208] The degree of wear was measured using an abrasion tester (Abrasion Tester (Heinrich Bareiss Prufgeratebau GmbH)) according to the following mathematical formula 2.

[0209] [Mathematical Formula 2]

[0210] (Mass before wear) / (Mass after wear) = Wear loss

[0211] FIG. 2 is a graph comparing the wet grip, rolling resistance, and wear of a rubber specimen prepared using a cardanol resin prepared according to a method for preparing a cardanol resin according to one embodiment of the present invention as a process oil, and a rubber specimen prepared using a process oil of an aromatic component resin.

[0212] [Table 2]

[0213]

[0214]

[0215] Table 2 above shows the road surface braking force, rolling resistance, and wear in Examples 1 to 5.

[0216] Referring to Figure 2 and Table 2, data for Manufacturing Example and Examples 1 to 5 were prepared based on the physical properties of Comparative Example 1 (TDAE), which is used as a conventional process oil.

[0217] While a lower rolling resistance value generally implies improved fuel efficiency, the reciprocal was taken for greater intuitiveness, so a higher value indicates superior rolling resistance characteristics. Similarly, although a lower wear value implies longer tire life, the reciprocal was taken for greater intuitiveness, so a higher value indicates superior tire life. For all scores representing physical properties on the graph, a higher value signifies superior performance.

[0218] Referring to Table 1 and Figure 2, the physical properties of a rubber specimen containing the cardanol petroleum resin of the example were confirmed in comparison to Comparative Example 1 (TDAE), which is used as a conventional seed oil.

[0219] In the case of the conventional cardanol of Comparative Example 2, the road braking force, rolling resistance, and wear resistance are inferior. On the other hand, in the case of Example 1, although the rolling resistance decreased slightly, the road braking was excellent and the wear resistance was also improved, exhibiting very excellent physical properties.

[0220] Meanwhile, in tire formulations, road braking performance and rolling resistance are in a trade-off relationship, so it is important to identify the optimal conditions that improve both properties simultaneously; as for wear, wear determines tire lifespan, and the higher the wear, the longer the tire lasts.

[0221] In Examples 1 to 5, it was confirmed that road surface braking and rolling resistance could be adjusted to an optimal range so that no single physical property deteriorates excessively compared to other physical properties, thereby confirming that it can replace conventional process oil and that wear resistance can also be improved.

[0222]

[0223] Experimental Example 4. Comparison of Carbon Emissions

[0224] FIG. 3 shows the amount of carbon emissions generated during the manufacturing process of a cardanol petroleum resin according to one embodiment of the present invention.

[0225] Referring to FIG. 3, it was confirmed that the cardanol petroleum resin containing low cardanol content of Examples 1 to 5 has a carbon emission reduction effect of 2.31 kg CO2 / kg or less, and that high carbon reduction is possible when replacing conventional TDAE.

[0226]

[0227] Accordingly, the present invention provides a cardanol petroleum resin comprising a cardanol and styrene copolymer, and the cardanol petroleum resin can replace process oil in rubber compositions for tire treads. The tire manufactured accordingly is not only highly environmentally friendly by significantly reducing carbon emissions compared to DAE (distillate aromatic extract) or TDAE, which contain a large amount of conventional aromatic components and cause environmental problems when used as process oils, but also exhibits physical properties equivalent to or better than TDAE by optimizing rolling resistance and road braking, which are in a trade-off relationship, and in particular, the wear resistance is improved, allowing it to be utilized as a rubber composition for electric vehicle tires.

[0228]

[0229] The present invention has been described above with reference to embodiments. Those skilled in the art will understand that the present invention may be embodied in modified forms without departing from the essential characteristics of the invention. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the invention is defined by the claims, not by the foregoing description, and all variations within the scope of equivalents should be interpreted as being included in the invention.

Claims

1. A copolymer comprising cardanol and styrene, Cardanol-based resin.

2. The cardanol-based resin according to claim 1, wherein the copolymer comprises 30% to 70% by weight of cardanol; and 30% to 70% by weight of styrene.

3. The cardanol resin according to claim 1, wherein the cardanol resin has an aromatization degree of 22% to 43%.

4. The cardanol resin according to claim 1, wherein the cardanol resin has a weight-average molecular weight (Mw) of 900 to 2000, a number-average molecular weight (Mn) of 600 to 900, and a molecular weight distribution (PDI) of 1.5 to 2.

5.

5. In paragraph 1, the cardanol-based resin is a cardanol-based resin having a carbon emission of 2.3 kg CO2 / kg or less.

6. (a) A step of preparing a monomer composition comprising a cardanol monomer, a styrene monomer, and a xylene solvent; (b) a step of preparing a reaction product by primary polymerizing the above monomer composition; (c) a step of preparing a polymer by secondary polymerizing the above reaction product; and (d) a step of recovering a cardanol-based resin by reducing the pressure of the polymer; comprising, Method for manufacturing cardanol-based resin.

7. A method for manufacturing a cardanol-based resin according to claim 6, wherein the first polymerization is performed in a continuous stirred tank reactor (CSTR) and the second polymerization is performed in a plug flow reactor (PFR) located downstream of the continuous stirred tank reactor.

8. A method for manufacturing a cardanol-based resin according to claim 6, wherein the secondary polymerization temperature is higher than the primary polymerization temperature.

9. A method for manufacturing a cardanol-based resin according to claim 7, wherein the volume of the plug flow reactor (PFR) is larger than the volume of the continuous stirred tank reactor (CSTR).

10. A process oil for a rubber composition for a tire tread, and The above process oil comprises a cardanol-styrene copolymer having a weight-average molecular weight (Mw) of 900 to 2000, a number-average molecular weight (Mn) of 600 to 900, and a molecular weight distribution (PDI) of 1.5 to 2.

5. Process oil for tire treads.

11. In item 10, the process oil is a process oil for tire treads having a degree of aromatization of 22% to 43%.

12. A rubber composition for a tire tread comprising a cardanol-based resin according to any one of claims 1 to 5.

13. The rubber composition for tire tread according to claim 12, wherein the rubber composition for tire tread comprises 10 to 50 parts by weight of cardanol-based resin per 100 parts by weight of raw rubber.

14. The rubber composition for a tire tread according to claim 12, wherein the rubber composition for a tire tread has a loss factor (tanδ) of 100 to 110 according to the measurement of wet road braking force (0℃) at a temperature range of -80 to 110℃ and 10Hz according to dynamic mechanical analysis, and a loss factor (tanδ) of 70 to 95 according to the measurement of rolling resistance (60℃).

15. The rubber composition for a tire tread according to claim 12, wherein the rubber composition for a tire tread has a wear value of 70 to 95 as measured by a wear tester.

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