Cellulose composite and rubber composition containing same

Abstract

The present invention relates to a cellulose compound, a method for preparing the same, and a rubber composition comprising the cellulose compound, the cellulose compound comprising cellulose fibers, and a first spacer and a second spacer distributed between the cellulose fibers, the first spacer comprises an organic monomer or polymer having a hydrophilic-lipophilic balance (HLB) value of from 8 to 18, and the second spacer comprises an organic monomer or polymer having an HLB value of from 1 to less than 8. In the cellulose compound, the first spacers distributed among the cellulose fibers are combined with hydroxyl groups on the surfaces of the cellulose fibers, so that the hydrogen-bond interaction among the fibers is inhibited, and the compatibility with resin is improved by the second spacers. Therefore, when the cellulose composite is used as a reinforcing agent in a resin, the dispersibility of cellulose fibers is improved, thereby preventing a decrease in mechanical properties of the resin.

Description

Technical Field

[0001] The present invention relates to a cellulose composite, in particular to a cellulose composite which can be redispersed in a thermosetting resin, and a rubber composition comprising the cellulose composite. Background Art

[0002] Thermosetting resins, such as synthetic rubber, harden when heated by causing cross-linking reactions between the main polymer chains, transforming the molecular structure into a three-dimensional network structure. Once hardened, it is difficult to soften again and maintains stable physical properties after molding. Generally speaking, thermosetting resins have excellent heat resistance, solvent resistance, chemical resistance, mechanical properties, electrical insulation, etc., and are used to manufacture various products that require the above characteristics, which can be mixed with a variety of fillers or reinforcing agents according to the purpose and function of the product.

[0003] If the filler or reinforcing agent is an inorganic component, it has the disadvantage of increasing the weight of the molded product due to its high specific gravity, making recycling difficult. In recent years, composites using natural cellulose as a reinforcing agent for thermosetting resins have received widespread attention.

[0004] Cellulose microfibers are refined in an aqueous environment to break down fiber aggregates (pulp) into strands to increase the specific surface area, forming a finely dispersed fiber network. In addition, in the above refining process, when the cellulose fiber content is high, the viscosity will increase excessively, so it is usually refined at a concentration of 3%-4%.

[0005] These cellulose microfibers may have poor dispersibility when used with hydrophobic thermosetting resins due to the hydrophilicity caused by surface hydroxyl groups and the cohesiveness caused by strong hydrogen bonds. Various attempts are being made to prevent this poor dispersibility problem.

[0006] For example, cellulose fibers can be mixed with additives to form a complex to control hydrophilicity and hydrogen bonding, and then dispersed into the resin. Since cellulose fibers are used in the form of a suspension, they need to go through a drying process to remove moisture.

[0007] Among the above drying methods, freeze drying is one of the methods. Freeze drying has the advantage of effectively inhibiting the hydrogen bonds of cellulose.

[0008] Figure 1 The structure of cellulose fibers obtained after freeze drying to remove water is schematically shown. During the drying process, even if the water molecules forming the matrix evaporate, the morphology of the cellulose is still maintained, but the disadvantage is that the drying time is long and the production cost is high.

[0009] On the other hand, cellulose fiber composites can be thermally dried in a simpler, more efficient, and cost-effective manner than freeze-drying, but the thermal drying method enhances the hydrogen bonding between the hydroxyl groups on the cellulose surface, making it difficult to redisperse when mixed with the resin, thus having limitations in improving the mechanical properties of the resin.

[0010] Therefore, it is necessary to develop a cellulose composite that can ensure dispersion stability in resin. Summary of the invention

[0011] Technical issues

[0012] The present invention aims to solve the above problems and provides a cellulose composite and a preparation method thereof, which can achieve excellent dispersibility by improving compatibility with resins while suppressing hydrogen bonding during thermal drying by adding spacers between cellulose fibers.

[0013] The present invention also provides a rubber composition comprising the cellulose composite.

[0014] Solution to the problem

[0015] On the one hand, the present invention provides a cellulose composite, which includes cellulose fibers and a first spacer and a second spacer distributed between the cellulose fibers, wherein the first spacer includes an organic monomer or polymer with a hydrophilic-lipophilic balance (HLB) value of 8 to 18, and the second spacer includes an organic monomer or polymer with an HLB value of 1 to less than 8.

[0016] On the other hand, the present invention provides a method for preparing a cellulose composite, comprising the following steps: (S1) adding a first spacer to a cellulose fiber suspension and stirring to obtain a first emulsion; (S2) adding a second spacer to the first emulsion and stirring to obtain a second emulsion; and (S3) drying and crushing the second emulsion in sequence, or integrating the drying and crushing processes, to obtain a powdered cellulose composite.

[0017] Another aspect of the present invention provides a rubber composition, which includes a cellulose composite, a thermosetting resin and an additive, wherein the content of the cellulose composite is 0.1-50 parts by weight based on 100 parts by weight of the thermosetting rubber.

[0018] Effects of the Invention

[0019] In the cellulose composite according to the present invention, the first spacer distributed between the cellulose fibers absorbs a large amount of water molecules by combining with the hydroxyl groups on the surface of the cellulose fibers, thereby inhibiting the hydrogen bonding between the fibers, and the second spacer improves the compatibility between the cellulose and the resin. Therefore, when the cellulose composite is used as a reinforcing agent for the resin, the dispersibility of the cellulose fibers is improved, thereby preventing the decline of the mechanical properties of the resin. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The structure of cellulose fibers obtained by freezing and vacuum evaporation of water according to a conventional method is schematically shown.

[0021] Figure 2 The structure of the cellulose composite obtained after evaporating water by thermal drying according to one embodiment of the present invention is schematically shown.

[0022] Figure 3 : is an optical microscope image showing changes in oil dispersibility and viscosity according to the content of the first spacer in the cellulose composite as determined in Experimental Example 1.

[0023] Figure 4 The cross-sectional images and analysis results of the rubber according to the content of the second spacer in the cellulose composite determined in Experimental Example 2 are shown.

[0024] Figure 5 The cross-sectional images and analysis results of rubbers prepared from the rubber compositions of Reference Examples (Control) and Examples are shown.

[0025] Figure 6 A comparison of mechanical properties of rubbers prepared from the rubber compositions of Examples and Comparative Examples is shown. DETAILED DESCRIPTION

[0026] The terms or words used in this specification and claims should not be interpreted as limited to their conventional or dictionary meanings, but should be interpreted as having meanings and concepts consistent with the technical concept of the present invention based on the principle that the inventor can appropriately define the concept of the term in order to interpret his own invention in the best way.

[0027] In addition, it should be understood that the embodiments described in this specification and the structures shown in the drawings are only the most preferred embodiments of the present invention and cannot represent all technical concepts of the present invention. Therefore, various equivalents and modifications may exist when submitting this application.

[0028] One embodiment of the present invention relates to a cellulose composite having a first spacer and a second spacer distributed between cellulose fibers, wherein the first spacer inhibits hydrogen bonding between fibers by binding to hydroxyl groups on the fiber surface, and the second spacer improves compatibility when the cellulose composite is mixed with a resin (e.g., a rubber resin).

[0029] Next, the components constituting the cellulose composite of the present invention will be described in detail.

[0030] The cellulose fibers can be made from a pulp selected from the group consisting of: bleached, unbleached, chemical or semi-chemical pulp derived from wood; bleached, unbleached, chemical or semi-chemical pulp derived from non-wood such as cotton, straw, bamboo, sugar cane, seaweed; and recycled pulp (such as deinked pulp (DIP), old corrugated cardboard (OCC), etc.). For example, cellulose pulp is a fiber aggregate having an outermost layer (primary wall) and multiple inner layers (secondary walls), and is refined by dispersing the pulp in water and subjecting it to shearing force to form cellulose fibers having a microfiber network, and can be modified by oxidation treatment, acid or alkali treatment, etc. as needed.

[0031] The cellulose fibers after the above refining treatment have a length of several millimeters (eg, 1-5 mm), a width of several tens of micrometers (eg, 10-60 μm), and an aspect ratio (length / width) of 10-500, such as 50-400 or 100-300.

[0032] Two types of spacers may be distributed between the cellulose fibers, specifically, a first spacer and a second spacer having different HLB values ​​may be distributed between the cellulose fibers.

[0033] The above HLB (hydrophile-lipophile balance) is an indicator of the balance between hydrophilicity and lipophilicity (hydrophobicity) within a molecule. The larger the HLB value, the higher the hydrophilicity ratio; the smaller the HLB value, the lower the hydrophilicity ratio.

[0034] The first spacer can be an organic monomer or polymer having a relatively larger HLB value than the second spacer, for example, an HLB value of 8 or more, 10 or more, or 11 or more, and 18 or less, 16 or less, or 14 or less, and can be located between cellulose fibers and combined with hydroxyl groups on the fiber surface.

[0035] The combination of the first spacer and the hydroxyl groups on the fiber surface can inhibit hydrogen bonding between fibers, and when drying to prepare a composite and dispersing the composite into a resin, the cellulose fibers can maintain a fiber morphology without aggregation, thereby achieving excellent dispersibility.

[0036] In addition, the first spacer may have a property of not decomposing or volatilizing at 100° C. or higher, so that it is not damaged during a drying process for removing moisture from cellulose fibers when preparing the composite. The molecular weight or weight average molecular weight of the first spacer is 100-30000 g / mol, specifically 100 g / mol or more, 200 g / mol or more, 500 g / mol or more, or 1000 g / mol or more, and 30000 g / mol or less, 10000 g / mol or less, 8000 g / mol or less, 4500 g / mol or less, 4000 g / mol or less, 3500 g / mol or less, or 3000 g / mol or less.

[0037] In one embodiment of the present invention, the first spacer may be one or more selected from polyoxyethylene-polyoxypropylene copolymer (HLB 14), polytetramethylene glycol (HLB 11-13), polyethylene glycol-4 monolaurate (HLB 9.8), polyethylene glycol-4 monooleate (HLB 8), polyethylene glycol-8 monolaurate (HLB 11.4), polysorbate 85 (HLB 11), polyoxyethylene (10) hexadecyl ether (HLB 12.9), polyoxyethylene (20) hexadecyl ether (HLB 15.7), polyoxyethylene (15) tridecyl ether (HLB 15.4) and isoprene-maleic anhydride copolymer (HLB 8.9).

[0038] In the cellulose composite of the present invention, the weight ratio of the first spacer to the cellulose fiber may be 0.1-1.2, specifically 0.3-1. When the weight ratio is within the range, the fiber can achieve the effect of inhibiting hydrogen bonding during the drying process.

[0039] The second spacer can be a substance that is more non-polar than the first spacer, such as an organic monomer or polymer having an HLB value of greater than 1, greater than 2 or greater than 3, and less than 8, less than 7 or less than 6, and a molecular weight or weight average molecular weight of 40-70000 g / mol; specifically greater than 100 g / mol, greater than 200 g / mol, greater than 300 g / mol, greater than 500 g / mol or greater than 1,000 g / mol, and less than 50000 g / mol, less than 10000 g / mol, less than 8000 g / mol, less than 4500 g / mol, less than 4000 g / mol, less than 3000 g / mol, less than 2000 g / mol or less than 1000 g / mol.

[0040] The second spacer may be distributed between the cellulose fibers together with the first spacer bonded to the hydroxyl groups on the fiber surface, thereby improving compatibility with the resin.

[0041] The improved compatibility brought by the second spacer can improve the dispersibility of the composite in the resin, thereby preventing the degradation of the mechanical properties of the resin.

[0042] Furthermore, similar to the first spacer, the second spacer may have a property of not being decomposed or volatilized at 100° C. or higher so as not to be damaged during a drying process for removing moisture from cellulose fibers when preparing a composite.

[0043] In one embodiment of the present invention, the second spacer can be one or more selected from alkenyl succinic anhydride (HLB 5-6), fatty acid esters (HLB 3-6), oleic acid (HLB 1.6), sorbitan monostearate (HLB 4.7), sorbitan tristearate (HLB 2.1), sorbitan monopalmitate (HLB 6.7), ethylene glycol monostearate (HLB 2.9), glycerol monostearate (HLB 3.8), polyethylene glycol-4 dilaurate (HLB 6), 1-butanol (HLB 4.4), 1,4-butanediol (HLB 7.6), isopropanol (HLB 5.3), butadiene-maleic anhydride copolymer (HLB 7.5), ethylene-maleic anhydride copolymer (HLB 7.5) and butadiene copolymer (HLB 1).

[0044] In the cellulose composite of the present invention, the weight ratio of the second spacer to the cellulose fiber may be 0.1-4, specifically 0.5-3.5. When the weight ratio is within the range, the compatibility between the fiber and the polymer can be improved.

[0045] Furthermore, in order to ensure the effects of suppressing inter-fiber hydrogen bonding and compatibility between fibers and polymers in the cellulose composite of the present invention, the weight ratio of the first spacer to the second spacer is advantageously in the range of 1:1-1:5, specifically 1:1.5-1:3.

[0046] The preparation method of the cellulose composite of the present invention comprises the following steps: (S1) adding a first spacer to a cellulose fiber suspension and stirring to obtain a first emulsion; (S2) adding a second spacer to the first emulsion and stirring to obtain a second emulsion; and (S3) thermally drying and crushing the second emulsion to obtain a powdered cellulose composite.

[0047] The cellulose fiber suspension may be obtained by dispersing a slurry of fiber aggregate in water at a concentration of 1-50 wt % (eg, 4-30 wt %) and stirring the mixture. The stirring may be performed at a rotation speed of 1000-3000 rpm for 5-30 minutes.

[0048] In the present invention, stirring can be performed using a rotary mixer, an ultrasonic homogenizer, a homomixer, or the like.

[0049] When the first spacer is added to the cellulose fiber suspension and stirred, the first spacer can combine with the hydroxyl groups on the surface of the cellulose fiber to form aggregates due to its HLB value of 8-18 and high hydrophilicity ratio, thereby achieving emulsification and obtaining the first emulsion. Through the emulsification process, the first spacer is located between the cellulose fibers, thereby inhibiting the hydrogen bonding between the fibers during the subsequent drying process.

[0050] In one embodiment of the present invention, the stirring to obtain the first emulsion may be performed at a rotation speed of 1000-3000 rpm for 20-40 minutes (eg, 30 minutes).

[0051] When the second spacer is added to the first emulsion and stirred, since the second spacer has a smaller HLB value than the first spacer, that is, an HLB value of 1 to less than 8 or 3-6, it can form aggregates with the first spacer distributed between the cellulose fibers, thereby achieving secondary emulsification to obtain the second emulsion. Through the secondary emulsification process, the second spacer can promote the uniform distribution of the first spacer, thereby improving the compatibility with the resin.

[0052] In one embodiment of the present invention, the stirring to obtain the second emulsion may be performed at a rotation speed of 1000-3000 rpm for 20-40 minutes (eg, 30 minutes).

[0053] In the second emulsion, the diameter of the first spacer particles may be 0.1-2 μm, and the diameter of the second spacer particles may be 1-200 μm.

[0054] Then, the second emulsion may be loaded into a tray, heat-dried, and then pulverized to obtain a powdered cellulose composite.

[0055] Thermal drying may be performed at 100-120° C. or 105-110° C. for 20-30 hours (eg, 24 hours).

[0056] Another method for obtaining a cellulose composite without going through the above-mentioned emulsion mixing, drying and pulverizing processes may include integrating the series of processes using a functionalized mixer.

[0057] Figure 2The structure of a cellulose composite obtained by removing moisture by heat drying according to one embodiment of the present invention is schematically shown. After drying, the cellulose fibers still maintain their shape, and the first spacer is distributed between the cellulose fibers, and the hydrogen bonding between the fibers is inhibited by binding to the hydroxyl groups on the surface of the cellulose fibers. The second spacer is distributed between the cellulose fibers together with the first spacer bound to the hydroxyl groups on the fiber surface, thereby improving the compatibility with the resin.

[0058] Therefore, when the cellulose composite of the present invention is used as a reinforcing agent in a resin, the dispersibility of the cellulose fibers can be improved, thereby preventing the mechanical properties of the resin from being deteriorated.

[0059] Therefore, the present invention provides a rubber composition comprising a cellulose composite, a thermosetting rubber and an additive.

[0060] The thermosetting rubber may be selected from one or more of chloroprene rubber, butadiene rubber, acrylonitrile butadiene rubber, styrene butadiene rubber, hydrogenated acrylonitrile butadiene rubber, ethylene propylene diene rubber, chlorinated polyethylene rubber, natural rubber, isoprene rubber, butyl rubber and silicone rubber.

[0061] In the rubber composition, the cellulose composite is a biomass material used as a reinforcing agent for the base thermosetting rubber, and its content can be 0.1-50 parts by weight, specifically 1-30 parts by weight, more specifically 3-25 parts by weight or 3-20 parts by weight based on 100 parts by weight of the thermosetting rubber. When the content of the cellulose composite is less than 0.1 parts by weight, its function as a reinforcing agent is difficult to fully manifest, and when it exceeds 50 parts by weight, it may lead to a decrease in the dispersion stability of the composite, thereby causing a decrease in the mechanical properties of the thermosetting rubber.

[0062] The additives can be used as auxiliary agents to improve the processability and physical properties of the rubber composition. Specifically, the additives can include one or more selected from pigments (such as carbon black), antioxidants (such as octyl diphenylamine), crosslinking accelerators (such as N,N'-ethylene thiourea) and crosslinking agents (such as zinc oxide), and their content can be appropriately selected according to the range conventionally used in the field of rubber product manufacturing.

[0063] The rubber composition can be obtained by adding the cellulose composite, thermosetting rubber and additives into an internal intermittent mixing device such as a BANBURY mixer, stirring at 5-100 rpm for 1-30 minutes at 40-150° C., and then the composition can be compression molded and cooled to prepare a rubber product.

[0064] Embodiments for carrying out the invention

[0065] Below, in order to help understand the present invention, will be described in detail by example. However, embodiments according to the present invention can be modified in a variety of different forms, and the scope of the present invention should not be interpreted as being limited to the following embodiments. Embodiments of the present invention are intended to provide a more comprehensive description for those of ordinary skill in the art.

[0066] Preparation Example 1

[0067] Bleached kraft pulp (length: 1-5 mm, width: 20-40 μm) was dispersed in water at a concentration of 3 wt%, and stirred at 1000-3000 rpm for 10 minutes to obtain a cellulose fiber suspension. A first spacer polyoxyethylene (POE)-polyoxypropylene (POP) copolymer having an average molecular weight of 2000 g / mol and an HLB value of 14 was added to the cellulose fiber suspension, and stirred at a rotation speed of 1000-3000 rpm for 30 minutes to obtain a first emulsion (viscosity of 3000-4000 cP at 25°C).

[0068] A second spacer alkenyl succinic anhydride (HLB 5-6; molecular weight 350 g / mol) having a lower HLB value than the first spacer was added to the first emulsion and stirred at 1000-3000 rpm for 30 minutes to obtain a second emulsion (viscosity 3500-4500 cP at 25°C).

[0069] In the second emulsion, the solid component comprises cellulose fibers, first spacer particles and second spacer particles in a weight ratio of 1:1:3. The diameter of the first spacer particles is 0.1-2 μm, and the diameter of the second spacer particles is 1 to less than 200 μm.

[0070] Subsequently, the second emulsion is freeze-dried at -30°C to -10°C for 24-48 hours and pulverized by a pulverizer to prepare a powdered cellulose composite.

[0071] Preparation Example 2

[0072] Bleached kraft pulp (length: 1-5 mm, width: 20-40 μm) was dispersed in water at a concentration of 3 wt%, and stirred at 1000-3000 rpm for 10 minutes to obtain a cellulose fiber suspension. A first spacer polyoxyethylene (POE)-polyoxypropylene (POP) copolymer having an average molecular weight of 2000 g / mol and an HLB value of 14 was added to the cellulose fiber suspension, and stirred at a rotation speed of 1000-3000 rpm for 30 minutes to obtain a first emulsion.

[0073] A second spacer alkenyl succinic anhydride (HLB 5-6; molecular weight 350 g / mol) having a lower HLB value than the first spacer was added to the first emulsion, and the mixture was stirred at a rotation speed of 1000-3000 rpm for 30 minutes to obtain a second emulsion.

[0074] In the second emulsion, the solid component comprises cellulose fibers, first spacer particles and second spacer particles in a weight ratio of 1:1:3. The diameter of the first spacer particles is 0.1-2 μm, and the diameter of the second spacer particles is 1 to less than 200 μm.

[0075] Then, the second emulsion was loaded into a tray, thermally dried at 105° C. for 24 hours, and pulverized with a pulverizer to prepare a powdered cellulose composite.

[0076] Figure 2 The structure of the cellulose composite obtained after evaporating water by thermal drying in the preparation example of the present invention is schematically shown.

[0077] Comparative Preparation Example 1

[0078] The cellulose composite was prepared in the same manner as in Preparation Example 2, except that sorbitan monooleate (having a lower HLB value of 4.3) was used as the first spacer.

[0079] Comparative Preparation Example 2

[0080] A cellulose composite was prepared in the same manner as in Preparation Example 2, except that polyoxyethylene (POE) (20) sorbitan monooleate (having a higher HLB value of 15) was used as the second spacer.

[0081] Comparative Preparation Example 3

[0082] The cellulose composite was prepared by the same method as in Preparation Example 2, except that sorbitan monooleate (with a lower HLB value of 4.3) was used as the first spacer and polyoxyethylene (POE) (20) sorbitan monooleate (with a higher HLB value of 15) was used as the second spacer.

[0083] Preparation Example 3

[0084] A cellulose composite was prepared in the same manner as in Preparation Example 2, except that an isoprene-maleic anhydride copolymer having an HLB value of 8.9 was used as the first spacer.

[0085] Preparation Example 4

[0086] A cellulose composite was prepared in the same manner as in Preparation Example 3, except that a butadiene copolymer (HLB value of 1) was used as the second spacer.

[0087] Comparative Preparation Example 4

[0088] A cellulose composite was prepared in the same manner as in Comparative Preparation Example 3, except that an isoprene-maleic anhydride copolymer having an HLB of 8.9 was used as the first spacer.

[0089] Preparation of Rubber Compositions Containing No Cellulose Composite (Control)

[0090] Reference Example 1

[0091] 100 parts by weight of chloroprene rubber (DENKA PS-40, DENKA) with a Mooney viscosity of 30 to 55 as a thermosetting rubber, 50 parts by weight of a 40 m 2 / g of carbon black (STATEX N550, BIRLA CARBON KOREA) as a pigment, 2 parts by weight of octyl diphenylamine (OCTAMINE, Addivant) with a melting point of 80°C as an antioxidant, 0.5 parts by weight of N,N'-ethylene thiourea (ETU-80, Rhein Chemie) with a specific gravity of 1.1 as a crosslinking accelerator, and 5 parts by weight of zinc oxide (Hanil Chemical) with a specific gravity of 5.6 as a crosslinking agent were mixed and stirred at 70°C at a rotation speed of 20 rpm for 20 minutes to prepare a rubber composition.

[0092] Preparation of rubber composition containing cellulose composite

[0093] Example 1

[0094] 16 parts by weight of the cellulose composite obtained in Preparation Example 1, 100 parts by weight of chloroprene rubber (DENKA PS-40, DENKA) with a Mooney viscosity of 30-55 as a thermosetting rubber, and 50 parts by weight of a cellulose ester with a specific surface area of ​​40 m 2 / g of carbon black (STATEX N550, BIRLA CARBON KOREA) as a pigment, 2 parts by weight of octyl diphenylamine (OCTAMINE, Addivant) with a melting point of 80°C as an antioxidant, 0.5 parts by weight of N,N'-ethylene thiourea (ETU-80, RheinChemie) with a specific gravity of 1.1 as a crosslinking accelerator, and 5 parts by weight of zinc oxide (Hanil Chemical) with a specific gravity of 5.6 as a crosslinking agent were mixed and stirred at 70°C at a rotation speed of 20 rpm for 20 minutes to prepare a rubber composition.

[0095] Example 2

[0096] A rubber composition was prepared by the same method as in Example 1, except that the composite obtained in Preparation Example 2 was used as the cellulose composite.

[0097] Comparative Example 1

[0098] A rubber composition was prepared using the same method as in Example 2, except that the composite obtained in Comparative Preparation Example 1 was used as the cellulose composite.

[0099] Comparative Example 2

[0100] A rubber composition was prepared by the same method as in Example 2, except that the composite obtained in Comparative Preparation Example 2 was used as the cellulose composite.

[0101] Comparative Example 3

[0102] A rubber composition was prepared using the same method as in Example 2, except that the composite obtained in Comparative Preparation Example 3 was used as the cellulose composite.

[0103] Example 3

[0104] A rubber composition was prepared by the same method as in Example 2, except that the composite obtained in Preparation Example 3 was used as the cellulose composite.

[0105] Example 4

[0106] A rubber composition was prepared by the same method as in Example 2, except that the composite obtained in Preparation Example 3 was used as the cellulose composite.

[0107] Comparative Example 4

[0108] A rubber composition was prepared by the same method as in Example 2, except that the composite obtained in Comparative Preparation Example 4 was used as the cellulose composite.

[0109] Experimental Example 1: Evaluation of dispersibility according to the first spacer content in the cellulose composite

[0110] A cellulose composite was prepared using the same method as in Preparation Example 2, except that the content of the first spacer (polyoxyethylene-polyoxypropylene copolymer, HLB 14) was varied within the range of 0-10 wt % based on the total weight of the composite.

[0111] After the above composites were redispersed in oil, their dispersibility was evaluated by optical microscopy and viscosity measurement. Figure 3 shown.

[0112] from Figure 3 It can be seen that as the content of the first spacer in the composite increases, the viscosity increases. This is because the first spacer inhibits the hydrogen bonding between cellulose fibers, resulting in fibrillation and the formation of a three-dimensional network.

[0113] Experimental Example 2: Evaluation of compatibility based on the content of the second spacer in the cellulose composite

[0114] A cellulose composite was prepared in the same manner as in Preparation Example 2, except that the content of the second spacer (alkenyl succinic anhydride, HLB 5-6) was varied within the range of 1-4 wt% of the total weight of the composite. A rubber composition was prepared using the composite in the same manner as in Example 1, and compression molding was performed to prepare a rubber specimen.

[0115] The cross section of the rubber sample was photographed using an optical microscope, and the cross-sectional image was analyzed with a standard of 500 × 420 (width × height) pixels to measure the average particle size and area ratio. The results are shown in Figure 4 shown.

[0116] Depend on Figure 4 It can be seen that as the content of the second spacer in the rubber sample increases, the average particle size and area ratio of the cellulose composite dispersed in the rubber decrease. This is because the second spacer contained in the cellulose composite improves the compatibility with the rubber resin, thereby improving the dispersibility.

[0117] Experimental Example 3: Evaluation of dispersibility based on application of heat-dried cellulose composite

[0118] The rubber compositions of Reference Example (control - no cellulose composite), Example 1 and Example 2 were compression molded to prepare rubber specimens.

[0119] The cross section of the rubber sample was photographed using an optical microscope, and the cross-sectional image was analyzed with a standard of 500 × 420 (width × height) pixels to measure the average particle size and area ratio. The results are shown in Figure 5 shown.

[0120] Depend on Figure 5 It can be seen that the test specimens prepared from the rubber compositions of Example 1 and Example 2 exhibit uniform dispersion.

[0121] Experimental Example 4: Evaluation of physical properties according to the application of cellulose composite

[0122] The rubber compositions of Reference Example, Example 1 and Example 2 were compression-molded to prepare rubber specimens, and the mechanical properties of the specimens were measured.

[0123] Modulus: The rubber sample was cut into a dumbbell shape according to the standard of JIS K 6251-1, and the tensile strength was measured by UTM (WithlAb). Specifically, the sample was cut into a size of 4 mm in width × 75 mm in length × 1 mm in thickness, and the force when the sample was stretched to 100%, 150% and 200% was measured at a tension speed of 254 mm / min and a clamping distance of 20 mm under the conditions of temperature 23°C and humidity 50%.

[0124] Hardness: The Shore A hardness of the rubber specimen was measured according to ASTM D 2240.

[0125] Oil resistance: After the rubber specimens were immersed in IRM 902 oil at 70°C for 72 hours, their tensile strength and elongation were measured.

[0126] The above test results are shown in Table 1.

[0127] [Table 1]

[0128]

[0129] In the above Table 1, it can be confirmed that the rubber sample of Reference Example 1 containing no cellulose composite in the rubber is inferior in modulus, hardness and oil resistance mechanical properties, while the rubber samples of Examples 1 and 2 exhibit excellent mechanical properties.

[0130] Experimental Example 5: Evaluation of physical properties based on the combination of the first spacer and the second spacer

[0131] The rubber compositions of Examples 1-2 and Comparative Examples 1-3 were respectively compression molded to prepare rubber specimens, and their mechanical properties were measured according to the method of Experimental Example 4. The results are shown in Tables 2 and Figure 6 shown.

[0132] [Table 2]

[0133]

[0134] In Table 2 above and Figure 6 In Examples 1 and 2, a first spacer having a higher HLB value and a second spacer having a lower HLB value are sequentially added to a cellulose fiber suspension to prepare a heat-dried cellulose composite, and the resulting composite is mixed with rubber, thereby achieving excellent mechanical properties. In contrast, the mechanical properties of Comparative Examples 1-3 are poor.

[0135] Specifically, Comparative Example 1 shows that when a first spacer and a second spacer having a relatively low HLB value and a small difference in HLB value are used in a heat-dried cellulose composite, the tensile strength and elongation of the rubber decrease. Comparative Example 2 shows that when a first spacer and a second spacer having a relatively high HLB value and a small difference in HLB value are used, the modulus and hardness of the rubber decrease. Comparative Example 3 shows that when a first spacer having a low HLB value and a second spacer having a high HLB value are sequentially mixed, the modulus and hardness decrease.

[0136] The mechanical properties of the rubber compositions of Examples 3-4 and Comparative Example 4 were measured in the same manner. The results are shown in Table 3.

[0137] [Table 3]

[0138]

[0139]

[0140] It can be seen from the results in Table 3 above that when a cellulose composite having an isoprene-maleic anhydride copolymer with an HLB value of 8.9 as the first spacer and alkenyl succinic anhydride (HLB 5-6) or butadiene copolymer (HLB 1) as the second spacer is blended with rubber, the tensile strength, modulus and hardness are improved compared to when a second spacer with a relatively higher HLB value is used.

Claims

1. A cellulose composite comprising cellulose fibers and a first spacer and a second spacer distributed between the cellulose fibers, wherein the first spacer comprises an organic monomer or polymer having a hydrophilic-lipophilic balance (HLB) value of 8 to 18, The second spacer includes an organic monomer or polymer having an HLB value of 1 to less than 8. 2 . The cellulose composite according to claim 1 , wherein the molecular weight or average molecular weight of the first spacer is 100-30,000 g / mol, and the molecular weight or average molecular weight of the second spacer is 40-70,000 g / mol.

3. The cellulose composite according to claim 1, wherein the cellulose fibers are obtained from: bleached, unbleached, chemical or semi-chemical pulp derived from wood; or bleached, unbleached, chemical or semi-chemical pulp derived from non-wood such as cotton, straw, bamboo, sugar cane or seaweed; or recycled pulp.

4. The cellulose composite according to claim 1, wherein the first spacer is selected from one or more of polyoxyethylene-polyoxypropylene copolymer, polytetrahydrofuran, polyethylene glycol-4 monolaurate, polyethylene glycol-4 monooleate, polyethylene glycol-8 monolaurate, polysorbate 85, polyoxyethylene (10) cetyl ether (HLB 12.9), polyoxyethylene (20) cetyl ether, polyoxyethylene tridecyl ether and isoprene-maleic anhydride copolymer.

5. The cellulose composite according to claim 1, wherein the second spacer is selected from one or more of alkenyl succinic anhydride, fatty acid esters, oleic acid, sorbitan monostearate, sorbitan tristearate, sorbitan monopalmitate, ethylene glycol monostearate, glycerol monostearate, polyethylene glycol-4 dilaurate, 1-butanol, 1,4-butanediol, isopropanol, butadiene-maleic anhydride copolymer, ethylene-maleic anhydride copolymer and butadiene copolymer. The cellulose composite according to claim 1 , wherein the weight ratio of the first spacer to the cellulose fibers is 0.1-1.

2. 7 . The cellulose composite according to claim 1 , wherein the weight ratio of the second spacer to the cellulose fibers is 0.1-4. The cellulose composite according to claim 1 , wherein a weight ratio of the first spacer to the second spacer is in the range of 1:1 to 1:

5.

9. A method for preparing a cellulose composite, comprising the steps of: (S1) adding a first spacer to a cellulose fiber suspension and stirring to obtain a first emulsion; (S2) adding a second spacer to the first emulsion and stirring to obtain a second emulsion; as well as (S3) The second emulsion is dried and pulverized in sequence, or the drying and pulverizing processes are integrated to obtain a powdered cellulose composite.

10. The method according to claim 9, wherein the stirring in steps (S1) and (S2) is performed at a rotation speed of 1000-3000 rpm for 20-40 minutes. 11 . The method according to claim 9 , wherein the diameter of the first spacer particles in the second emulsion is 0.1-2 μm. 12 . The method according to claim 9 , wherein the diameter of the second spacer particles in the second emulsion is 1-200 μm.

13. A rubber composition comprising the cellulose composite according to claim 1, a thermosetting rubber and an additive; wherein: The cellulose composite may be included in an amount of 0.1 to 50 parts by weight based on 100 parts by weight of the thermosetting rubber.

14. The rubber composition according to claim 13, wherein the thermosetting rubber is selected from one or more of chloroprene rubber, butadiene rubber, acrylonitrile butadiene rubber, styrene butadiene rubber, hydrogenated acrylonitrile butadiene rubber, ethylene propylene diene rubber, chlorinated polyethylene rubber, natural rubber, isoprene rubber, butyl rubber and silicone rubber.

15. The rubber composition according to claim 13, wherein the additive comprises one or more selected from the group consisting of carbon black, an antioxidant, a crosslinking accelerator, and a crosslinking agent.

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