Polymer composite and molded article containing same

Abstract

The present invention relates to a polymer composite and a molded article containing the same. According to the present invention, there is provided a polymer composite that contains cellulose fibers as a fiber reinforcing material, is environmentally friendly, and exhibits excellent mechanical properties.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0107619, filed August 13, 2021, and Korean Patent Application No. 10-2022-0077701, filed June 24, 2022, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to polymer composites containing fiber reinforcement and impact reinforcement and molded articles containing the same. [Background technology]

[0003] Pulp is a lignocellulosic fibrous material obtained by chemically or mechanically separating cellulose fibers from wood, fiber crops, waste paper, rags, etc. Cellulose fibers are mainly used in the papermaking industry and are utilized as a raw material for nanocellulose.

[0004] Nanocellulose is being used in research to improve the physical properties of polymers by combining them with polymers. Unlike polymer composites that use glass fiber as a fiber reinforcement, polymer composites that use environmentally friendly nanocellulose have the advantage of being easily recyclable.

[0005] However, the process of producing nanocellulose from cellulose fibers is complicated and costly. Furthermore, cellulose fibers can deteriorate due to the high processing temperatures during the polymer composite process. Furthermore, cellulose fibers and nanocellulose tend to aggregate within the polymer composite, making it extremely difficult to disperse them at the nanoscale, limiting the ability to achieve sufficient reinforcing effects. Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention provides a polymer composite that contains cellulose fibers as a fiber reinforcement material, is environmentally friendly, and exhibits excellent mechanical properties.

[0007] The present invention also provides a molded article comprising the polymer composite. [Means for solving the problem]

[0008] Hereinafter, a polymer composite and a molded article including the same according to an embodiment of the present invention will be described.

[0009] Unless expressly stated otherwise herein, terminology is for the purpose of referring to particular embodiments only and is not intended to be limiting of the invention.

[0010] As used herein, the singular forms "a," "an," and "the" include the plural forms as well, unless the context clearly indicates otherwise.

[0011] As used herein, the meaning of "comprising" embodies certain properties, regions, integers, steps, operations, elements, and / or components, and does not exclude the presence or addition of other certain properties, regions, integers, steps, operations, elements, components, and / or groups.

[0012] As used herein, "nanofiber" or "nanofibril" refers to a fiber having a diameter on the nanometer scale, and "microfiber" refers to a fiber having a diameter on the micrometer scale. For example, the microfiber may be composed of a bundle of the nanofibers. As used herein, the "diameter" of various fibers and fibrils refers to the diameter of the longest length in their cross section.

[0013] As used herein, "pulp" refers to a lignocellulosic fibrous material obtained by chemically or mechanically separating cellulose fibers from wood, fiber crops, waste paper, rags, or the like.

[0014] As used herein, "pulp fibers," "cellulose fibers," or "microcellulose fibers" refer to microfibers made of cellulose. As used herein, "cellulose nanofibers" or "first microcellulose fibers" refer to nanofibers made of cellulose.

[0015] In this specification, "fibrillation" refers to the phenomenon in which nanofibrils forming the internal structure of microcellulose fibers are loosened and the nanofibrils become fluffy on the microcellulose fibers.

[0016] As used herein, the term "fibrillated cellulose fibers" refers to microcellulose fibers in which nanofibrils having nanometer-scale diameters have been formed on the microcellulose fibers as a result of the fibrillation.

[0017] According to one embodiment of the present invention, a polymer matrix, and including a fiber reinforcement material containing cellulose fibers; A polymer composite is provided having an Izod impact strength of 30 J / m or more, measured in accordance with the standard test method of ASTM D256 (23°C, hammer head 3.00 J) on a notched test specimen of ASTM D256 standard size 63.5 mm x 12.7 mm x 3.2 mm.

[0018] As a result of extensive research, the inventors have confirmed that a polymer composite obtained by dispersing a fiber reinforcement material containing cellulose fiber and an impact reinforcement material containing rubber in a polymer matrix containing a thermoplastic plastic is environmentally friendly and can exhibit excellent mechanical properties.

[0019] The polymer composite according to an embodiment of the present invention includes the fiber reinforcement dispersed within the polymer matrix.

[0020] The polymer composite may further include a rubber dispersed within the polymer matrix.

[0021] The polymer matrix may be a polymer resin.

[0022] As an example, the polymer matrix may include one or more polymers selected from the group consisting of polyolefins, polyamides, styrene-based polymers, and polycarbonates.

[0023] Specifically, the polymer matrix may be a polyolefin such as polyethylene, polyethylene-based copolymers, polypropylene, and polypropylene-based copolymers; an aliphatic polyamide such as nylon-6 and nylon-66; an aromatic polyamide such as aramid; a styrene-based polymer such as polystyrene, acrylonitrile-butadiene-styrene copolymer, styrene-maleic anhydride copolymer, styrene-acrylonitrile copolymer, and styrene-butadiene-styrene copolymer; or a polycarbonate obtained by polymerizing phosgene with a polyol including bisphenol A, polyether polyol, polyester polyol, or a mixture thereof.

[0024] Preferably, the polymer matrix may contain one or more polymer resins selected from the group consisting of polyethylene, polyethylene-based copolymers, polypropylene, polypropylene-based copolymers, nylon-6, nylon-66, aramid, polystyrene, acrylonitrile-butadiene-styrene copolymers, styrene-maleic anhydride copolymers, styrene-acrylonitrile copolymers, styrene-butadiene-styrene copolymers, and polycarbonates.

[0025] According to an embodiment of the present invention, the polymer composite comprises the fiber reinforcement dispersed on the polymer matrix.

[0026] The fiber reinforcement includes cellulose fibers.

[0027] The cellulose fibers may be natural cellulose fibers obtained from wood such as coniferous trees, broad-leaved trees, etc. For example, the cellulose fibers may be pulp fibers obtained by dissolving components other than cellulose from natural raw materials such as coniferous trees or broad-leaved trees using caustic soda, sodium sulfate, etc.

[0028] Preferably, the cellulose fibers may be microcellulose fibers comprising nanofibrils and second inorganic particles.

[0029] Cellulose nanofibers, a biodegradable and environmentally friendly natural polymer material, have recently attracted attention as a reinforcing material for plastics. However, the process of nano-sizing (fine-sizing) microcellulose fibers to obtain nanofibers is complex and costly, which increases the cost of polymer composites containing cellulose nanofibers as a fiber reinforcement.

[0030] According to the present invention, when cellulose fibers are not nanosized, but second inorganic particles are grown on microcellulose fibers to fibrillate the microcellulose fibers, and then the microcellulose fibers are composited with a polymer matrix, excellent mechanical properties equivalent to those of those using cellulose nanofibers can be exhibited.

[0031] The microcellulose fibers may be natural cellulose fibers obtained from wood such as softwoods and hardwoods.

[0032] Generally, fibrillation of microcellulose fibers refers to the phenomenon in which relatively large fibrils that form the membrane and internal structure of cellulose fibers are broken down through processes such as beating, resulting in the formation of fine fibrils on the surface.

[0033] In the present invention, the microcellulose fibers are cellulose fibers fibrillated by growing second inorganic particles on the cellulose fibers. That is, in the present invention, the microcellulose fibers containing the nanofibrils and second inorganic particles may be fibers in a state in which some of the fibrils forming the microcellulose fibers have been loosened or defibrated by the growth of the second inorganic particles on the microcellulose fibers.

[0034] FIG. 1(a) is an enlarged schematic view of non-fibrillated microcellulose fibers, and FIG. 1(b) is an enlarged schematic view of microcellulose fibers containing nanofibrils and second inorganic particles.

[0035] In Fig. 1(a), unfibrillated microcellulose fibers 100 are fibers with a diameter on the micrometer scale. Referring to Fig. 1(b), when inorganic particles are grown on cellulose fibers, some of the fibrils forming the microcellulose fibers 100' are loosened by the growth of the inorganic particles 20, and fibers with fluffy nanofibrils 11 are formed on the microcellulose fibers 100'. Furthermore, the nanofibrils 11 may also be present inside the microcellulose fibers 100' due to fibrillation caused by the growth of the inorganic particles 20.

[0036] In one example, the microcellulose fibers comprise nanofibrils and second inorganic particles, where the nanofibrils may be attached to the surface of the microcellulose fibers or may be present within the microcellulose fibers, and the second inorganic particles are attached to the nanofibrils or attached to the surface or within the microcellulose fibers.

[0037] The microcellulose fibers comprising the nanofibrils and second inorganic particles may have a diameter of 1 μm or more and 30 μm or less, alternatively 25 μm or less, alternatively 20 μm or less, alternatively 15 μm or less, or alternatively 10 μm or less. Specifically, the microcellulose fibers may have a diameter of 1 μm to 30 μm, alternatively 1 μm to 25 μm, alternatively 1 μm to 20 μm, alternatively 1 μm to 15 μm, or alternatively 1 μm to 10 μm.

[0038] In the microcellulose fibers containing the nanofibrils and second inorganic particles, the nanofibrils may have a diameter of 10 nm or more, alternatively 20 nm or more, alternatively 30 nm or more, alternatively 40 nm or more, alternatively 50 nm or more; and 400 nm or less, alternatively 350 nm or less, alternatively 300 nm or less, alternatively 250 nm or less, alternatively 200 nm or less, alternatively 150 nm or less, or alternatively 100 nm or less. Specifically, the nanofibrils may have a diameter of 10 nm to 400 nm, alternatively 10 nm to 350 nm, alternatively 10 nm to 300 nm, alternatively 20 nm to 300 nm, alternatively 20 nm to 250 nm, alternatively 30 nm to 250 nm, alternatively 30 nm to 200 nm, alternatively 40 nm to 200 nm, alternatively 40 nm to 150 nm, alternatively 50 nm to 150 nm, or alternatively 50 nm to 100 nm.

[0039] The lengths of the second microcellulose fibers and the nanofibrils are not particularly limited.

[0040] The microcellulose fibers containing the nanofibrils and second inorganic particles can be produced by adding a reducing agent, catalyst, ligand, or a mixture thereof to a mixture containing microcellulose fibers, a second inorganic particle precursor, and a solvent, to grow second inorganic particles from the second inorganic particle precursor distributed on the cellulose fibers.

[0041] In one example, the process includes providing a mixture including microcellulose fibers, a second inorganic particle precursor, and a solvent.

[0042] The solvent may be a compound capable of dissolving the second inorganic particle precursor and swelling the microcellulose fibers. For example, the solvent may be water, alcohol (e.g., lower alcohol such as methanol, ethanol, propanol, or butanol), dimethyl sulfoxide, aqueous sodium hydroxide solution, aqueous ammonia solution, aqueous urea solution, or a mixture thereof.

[0043] The solvent can be used in an amount of 1,000 to 10,000 parts by weight per 100 parts by weight of microcellulose fibers. Within this solvent content range, the microcellulose fibers are sufficiently swollen, the fluidity of the second inorganic particle precursor is ensured, and the second inorganic particle precursor can be uniformly dispersed on the microcellulose fibers.

[0044] Depending on the type of second inorganic particles grown on the microcellulose fibers, a polymer composite with various physical properties can be provided. That is, the second inorganic particle precursor can be appropriately selected depending on the physical properties to be imparted to the polymer composite. As a non-limiting example, a second inorganic particle precursor capable of growing zinc oxide can be selected to impart antibacterial and heat resistance to the polymer composite.

[0045] For example, the second inorganic particles may contain one or more elements selected from the group consisting of copper, zinc, calcium, aluminum, iron, platinum, palladium, ruthenium, iridium, rhodium, osmium, chromium, cobalt, nickel, manganese, vanadium, molybdenum, and gallium. The inorganic particles may contain one or more elements. For example, the second inorganic particles may be the above-mentioned metal particles, or oxides, nitrides, or sulfides thereof.

[0046] The second inorganic particle precursor may be a salt of one or more elements selected from the group consisting of copper, zinc, calcium, aluminum, iron, platinum, palladium, ruthenium, iridium, rhodium, osmium, chromium, cobalt, nickel, manganese, vanadium, molybdenum, and gallium. The salt may be an acetate, chloride, or nitrate. Alternatively, the second inorganic particle precursor may be a silicon oxide precursor such as tetraethyl orthosilicate (TEOS).

[0047] The content of the second inorganic particles may be 10 to 40 parts by weight per 100 parts by weight of the microcellulose fibers. Specifically, the content of the second inorganic particles may be 10 parts by weight or more, or 15 parts by weight or more; and 40 parts by weight or less, or 35 parts by weight or less, or 30 parts by weight or less per 100 parts by weight of the microcellulose fibers. Preferably, the content of the second inorganic particles may be 10 to 40 parts by weight, or 10 to 35 parts by weight, or 15 to 35 parts by weight, or 15 to 30 parts by weight per 100 parts by weight of the microcellulose fibers. Therefore, the content of the second inorganic particle precursor contained in the mixture can be controlled so that the content of the second inorganic particles finally formed on the microcellulose fibers falls within the above range. Within this content range, the second inorganic particle precursor is uniformly distributed on the microcellulose fibers, inducing sufficient fibrillation and enabling the development of improved mechanical properties.

[0048] The mixture is prepared by dissolving the second inorganic particle precursor in the solvent and then adding microcellulose fibers. The mixture is stirred to swell the microcellulose fibers and simultaneously distribute the second inorganic particle precursor uniformly on the swollen microcellulose fibers. The second inorganic particle precursor adheres to the microcellulose fibers through hydrogen or ionic bonds.

[0049] The types and amounts of the reducing agent, catalyst, and ligand added to the mixture can be appropriately selected depending on the added second inorganic particle precursor and the type and amount of the second inorganic particles to be grown. For example, the reducing agent can be sodium hydroxide (NaOH), a metal hydride, a borohydride, a borane, a silane, a hydrazine, or a hydrazide reducing agent. The catalyst can be ammonia or urea. The ligand can be benzene-1,3,5-tricarboxylate.

[0050] 2 and 3 are scanning electron microscope (SEM) images of microcellulose fibers fibrillated by the growth of the second inorganic particles according to one example of the present invention.

[0051] Referring to the image in Figure 2(a), it can be seen that the second inorganic particles have grown on the microcellulose fibers, resulting in fibrillation. The image in Figure 2(b) is a further enlarged view of a portion of the image in Figure 2(a).

[0052] Referring to FIG. 3, it can be seen that (a) the metal element (zinc) and (b) oxygen are uniformly distributed on the microcellulose fibers due to the growth of the second inorganic particles.

[0053] The process results in microcellulose fibers containing the nanofibrils and second inorganic particles.

[0054] According to an embodiment of the present invention, the second inorganic particles contained in the microcellulose fibers may have a diameter of 0.01 μm or more, alternatively 0.03 μm or more, alternatively 0.05 μm or more, and 10 μm or less, alternatively 7 μm or less, alternatively 5 μm or less. Preferably, the second inorganic particles have a diameter of 0.01 μm to 10 μm, alternatively 0.03 μm to 7 μm, alternatively 0.05 μm to 5 μm.

[0055] If the particle size of the second inorganic particles contained on the microcellulose fibers is too large, the second inorganic particles may act as defects, deteriorating the mechanical properties of the polymer composite. Therefore, the particle size of the second inorganic particles is preferably 10 μm or less, or 7 μm or less, or 5 μm or less.

[0056] In order to ensure sufficient fibrillation of the microcellulose fibers due to the growth of the second inorganic particles, it is preferable that the particle size of the second inorganic particles is 0.01 μm or more, or 0.03 μm or more, or 0.05 μm or more.

[0057] The second inorganic particles may be spherical particles having a diameter of 0.01 μm to 10 μm. Alternatively, the second inorganic particles may be columnar particles having a uniaxial diameter of 0.01 μm to 10 μm and another uniaxial diameter of 0.02 μm to 30 μm. The diameter of the second inorganic particles may be measured using a scanning electron microscope. As a non-limiting example, the diameter, minor axis diameter, or major axis diameter of 20 second inorganic particles may be measured using a scanning electron microscope, and then the maximum and minimum values ​​may be excluded to obtain an average value.

[0058] According to an embodiment of the present invention, the second inorganic particles may be included in an amount of 10 parts by weight or more, alternatively 15 parts by weight or more, and 40 parts by weight or less, alternatively 35 parts by weight or less, alternatively 30 parts by weight or less, relative to 100 parts by weight of the microcellulose fibers. Preferably, the second inorganic particles may be included in an amount of 10 to 40 parts by weight, alternatively 10 to 35 parts by weight, alternatively 15 to 35 parts by weight, alternatively 15 to 30 parts by weight, relative to 100 parts by weight of the microcellulose fibers.

[0059] In order to fully realize the fibrillation effect and mechanical properties of the microcellulose fibers due to the growth of the second inorganic particles, it is preferable that the second inorganic particles are contained in an amount of 10 parts by weight or more, or 15 parts by weight or more, per 100 parts by weight of the microcellulose fibers.

[0060] However, if the second inorganic particles are contained in the microcellulose fibers in excess, their compatibility with the polymer matrix may decrease, which may result in deterioration of the mechanical properties of the polymer composite. Therefore, it is preferable that the second inorganic particles be contained in an amount of 40 parts by weight or less, 35 parts by weight or less, or 30 parts by weight or less per 100 parts by weight of the microcellulose fibers.

[0061] According to an embodiment of the present invention, the cellulose fibers may be a mixture of first microcellulose fibers; and second microcellulose fibers comprising nanofibrils and second inorganic particles.

[0062] The first microcellulose fibers may be natural cellulose fibers obtained from wood such as coniferous trees, broad-leaved trees, etc. For example, the first microcellulose fibers may be obtained by dissolving components other than cellulose from natural raw materials such as coniferous trees or broad-leaved trees using caustic soda, sodium sulfate, etc.

[0063] The first microcellulose fibers refer to microcellulose fibers that are not fibrillated compared to the microcellulose fibers containing the nanofibrils and second inorganic particles described above (i.e., fibrillated cellulose fibers).

[0064] The first microcellulose fibers may have a diameter of 10 μm to 40 μm and a length of 0.1 mm to 3 mm. Specifically, the first microcellulose fibers may have a diameter of 10 μm to 40 μm, alternatively 15 μm to 40 μm, alternatively 15 μm to 35 μm, alternatively 15 μm to 30 μm; and a length of 0.1 mm to 3 mm, alternatively 0.1 mm to 2.5 mm, alternatively 0.2 mm to 2.5 mm, alternatively 0.2 mm to 2 mm.

[0065] The first microcellulose fibers can be obtained by a wet method or a dry method. For example, the first microcellulose fibers can be obtained by adding a cellulose raw material to distilled water, grinding the raw material in a wet state in a mixer several times, and then filtering the raw material under reduced pressure.

[0066] The second microcellulose fibers containing the nanofibrils and second inorganic particles may be fibers in a state in which some of the fibrils forming the second microcellulose fibers have been loosened or defibrated due to the growth of the second inorganic particles on the microcellulose fibers. The nanofibrils, the second inorganic particles, and the microcellulose fibers containing them are as described above.

[0067] According to an embodiment of the present invention, the first microcellulose fibers and the second microcellulose fibers containing the nanofibrils and second inorganic particles may be contained in the polymer composite in a weight ratio of 1:0.1 to 1:3.

[0068] In other words, in order to reduce the manufacturing cost of the polymer composite and improve the mechanical properties, it is preferable that the second microcellulose fibers be contained in the polymer composite at a weight ratio of 0.1 times or more, or 0.2 times or more, based on the first microcellulose fibers.

[0069] However, if the content of the second microcellulose fibers is excessively high compared to the first microcellulose fibers, the total amount of inorganic particles contained in the polymer composite increases relatively, which may result in a decrease in the mechanical properties of the polymer composite. Therefore, it is preferable that the second microcellulose fibers be contained in the polymer composite at a weight ratio of 3 times or less, 2.5 times or less, 2 times or less, 1.5 times or less, 1.2 times or less, or 1 time or less of the first microcellulose fibers.

[0070] Preferably, the first microcellulose fibers and the second microcellulose fibers may be contained in the polymer composite in a weight ratio of 1:0.1 to 1:3, alternatively 1:0.1 to 1:2.5, alternatively 1:0.1 to 1:2, alternatively 1:0.1 to 1:1.5, alternatively 1:0.2 to 1:1.5, alternatively 1:0.2 to 1:1.2, alternatively 1:0.2 to 1:1.

[0071] According to an embodiment of the present invention, the polymer composite may further include rubber as an impact modifier dispersed on the polymer matrix.

[0072] The impact modifier is a component added to improve the impact strength of the polymer composite, which is one of the mechanical properties of the polymer composite.

[0073] The impact modifier may include natural rubber, synthetic rubber, or a mixture thereof. Preferably, the impact modifier may include one or more rubbers selected from the group consisting of ethylene-butene rubber (EBR), ethylene-octene rubber (EOR), ethylene-propylene rubber (EPR), styrene-butadiene rubber (SBR), and nitrile-butadiene rubber (NBR).

[0074] The impact modifier may be rubber particles having an average particle size of several millimeters. However, the impact modifier may not be present in the polymer composite in a particle state, but may be present in a uniformly mixed state with other components. As a non-limiting example, the impact modifier may have a melt index (@190°C, 2.16 kg) of 4.0 g / 10 min to 6.0 g / 10 min and a viscosity of 0.75 g / cm to ensure dispersion within the polymer composite. 3 ~0.95g / cm 3 It is preferred that the density of the granular material is 0.05 to 0.15.

[0075] According to one embodiment of the present invention, the polymer composite comprises: 5 to 90% by weight of the polymer matrix; 5 to 60% by weight of a fiber reinforcement material containing the cellulose fiber, and The rubber may comprise 1 to 60% by weight.

[0076] According to one embodiment of the present invention, the polymer composite comprises: 5 to 85 wt. % of the polymer matrix; 5 to 55% by weight of a fiber reinforcement material containing the cellulose fiber, and The rubber may comprise 2.5 to 55% by weight.

[0077] According to one embodiment of the present invention, the polymer composite is 5 to 80% by weight of the polymer matrix; 5 to 45% by weight of a fiber reinforcement material containing the cellulose fiber, and The rubber may comprise 2.5 to 50% by weight.

[0078] To provide a polymer composite containing an appropriate amount of matrix, the polymer matrix is ​​preferably contained in the polymer composite at 5 wt% or more. To achieve the improved mechanical properties of the present invention, the polymer matrix is ​​preferably contained in the polymer composite at 90 wt% or less, or 85 wt% or less, or 80 wt% or less. Specifically, the polymer matrix is ​​contained in the polymer composite at 5 to 90 wt%, or 5 to 85 wt%, or 5 to 80 wt%.

[0079] To achieve improved mechanical properties according to the present invention, the cellulose fiber-containing fiber reinforcement is preferably included in the polymer composite at 5 wt% or more. However, excessive fiber reinforcement may hinder compatibility with the polymer matrix, thereby reducing the mechanical properties of the polymer composite. Therefore, the cellulose fiber-containing fiber reinforcement is preferably included in the polymer composite at 60 wt% or less, alternatively 55 wt% or less, alternatively 50 wt% or less, or alternatively 45 wt% or less. Specifically, the fiber reinforcement is included in an amount of 5 to 60 wt%, alternatively 5 to 55 wt%, alternatively 5 to 50 wt%, or alternatively 5 to 45 wt%.

[0080] To achieve the impact strength improvement effect of the present invention, the rubber is preferably contained in the polymer composite at 1 wt % or more, or 2.5 wt % or more. However, excessive rubber may hinder compatibility with the polymer matrix, thereby reducing the mechanical properties of the polymer composite. Therefore, the rubber is preferably contained in the polymer composite at 60 wt % or less, or 55 wt % or less, or 50 wt % or less. Specifically, the rubber is contained in the polymer composite at 1 to 60 wt %, or 1 to 55 wt %, or 2.5 to 55 wt %, or 2.5 to 50 wt %.

[0081] Meanwhile, according to an embodiment of the present invention, the polymer composite may include first inorganic particles dispersed on the polymer matrix.

[0082] The first inorganic particles can be added as a color concealing material to improve the color of the polymer composite without reducing the mechanical properties of the polymer composite. For example, polymer composites containing cellulose fibers generally have a light or dark yellow color, but the addition of the first inorganic particles can improve the whiteness of the polymer composite.

[0083] The first inorganic particles may be inorganic particles having a high refractive index, and preferably include one or more inorganic particles selected from the group consisting of titanium oxide, zinc oxide, boron nitride, and barium sulfate.

[0084] The first inorganic particles may be inorganic particles having an average particle size of 50 nm to 1000 nm, or 100 nm to 1000 nm, or 100 nm to 500 nm. To ensure that the first inorganic particles are efficiently incorporated into the polymer composite, the first inorganic particles preferably have an average particle size of 50 nm or more, or 100 nm or more. However, excessively large inorganic particles may act as defects in the polymer composite and degrade mechanical properties. Therefore, the first inorganic particles preferably have an average particle size of 1000 nm or less, or 500 nm or less.

[0085] To achieve the color improvement effect, the first inorganic particles are preferably contained in the polymer composite at 0.1 wt % or more, 1 wt % or more, or 2.5 wt % or more. However, excessive inorganic particles may hinder compatibility with the polymer matrix, thereby reducing the mechanical properties of the polymer composite. Therefore, the first inorganic particles are preferably contained in the polymer composite at 20 wt % or less, 17.5 wt % or less, or 15 wt % or less. Specifically, the first inorganic particles are contained in the polymer composite at 0.1 to 20 wt %, 1 to 20 wt %, 2.5 to 20 wt %, 2.5 to 17.5 wt %, or 2.5 to 15 wt %.

[0086] For example, the polymer composite containing the first inorganic particles may satisfy the following formula 1: [Formula 1] L*≧90.0 In the above formula 1, the L* value is the lightness in the L*a*b* (CIE LAB) color system measured using a spectrophotometer on a test piece made of the polymer composite.

[0087] The L*a*b* (CIE LAB) color system is a method of expressing color tones for evaluating hue, and was established by the International Commission on Illumination (CIE) to represent colors visible to the human eye as a color space. This lightness (L* value) is an index that indicates the tendency of brightness and ranges from 0 to 100.

[0088] Preferably, the polymer composite can exhibit an L* value of 90.0 or more, or 90.2 or more; and 98.0 or less, or 97.5 or less. Specifically, the polymer composite can exhibit an L* value of 90.0 to 98.0, or 90.2 to 98.0, or 90.2 to 97.5. The L* value can be measured in reflectance mode on a test piece of an appropriate size using a spectrophotometer.

[0089] To ensure excellent mechanical properties, the total amount of the first inorganic particles and the second inorganic particles is preferably 5 parts by weight or more per 100 parts by weight of the polymer composite. However, excessive inorganic particles may hinder compatibility with the polymer matrix, thereby reducing the mechanical properties of the polymer composite. Therefore, the total amount of the first inorganic particles and the second inorganic particles is preferably 20 parts by weight or less per 100 parts by weight of the polymer composite.

[0090] For example, the total amount of the first inorganic particles and the second inorganic particles is preferably 5 parts by weight or more, or 5.5 parts by weight or more, or 6 parts by weight or more, and 20 parts by weight or less, or 17 parts by weight or less, or 15 parts by weight or less, or 10 parts by weight or less, relative to 100 parts by weight of the polymer composite. Specifically, the total amount of the first inorganic particles and the second inorganic particles is 5 to 20 parts by weight, or 5.5 to 20 parts by weight, or 5.5 to 17 parts by weight, or 6 to 17 parts by weight, or 6 to 15 parts by weight, or 6 to 10 parts by weight, relative to 100 parts by weight of the polymer composite.

[0091] Meanwhile, the polymer composite may further include a compatibilizer dispersed on the polymer matrix, which is a component that helps the polymer matrix and the fiber reinforcement to blend well with each other.

[0092] The compatibilizer may be any of those known in the art, taking into consideration the specific type of polymer matrix.

[0093] Preferably, the compatibilizer may be a modified polyolefin, which refers to a resin obtained by modifying a polyolefin with an unsaturated carboxylic acid or a derivative thereof.

[0094] The polyolefin forming the modified polyolefin may be a linear olefin such as ethylene, propylene, butene, pentene, hexene, and heptene; a cyclic olefin such as cyclopentene, cyclohexene, and 1,3-cyclopentadiene; or an olefin substituted with an aromatic ring such as styrene.

[0095] The unsaturated carboxylic acid forming the modified polyolefin can be fumaric acid, maleic acid, itaconic acid, citraconic acid, aconitic acid, and anhydrides thereof.

[0096] As a non-limiting example, the modified polyolefin may be polypropylene or polyethylene grafted with 0.1 to 10% by weight of maleic anhydride.

[0097] Such modified polyolefins can further improve the compatibility of cellulose fibers with the polymer matrix, thereby further improving the mechanical properties of the polymer composite.

[0098] To achieve appropriate compatibility, the compatibilizer is contained in the polymer composite at 0.1 wt % or more, or 1 wt % or more, or 2.5 wt % or more. However, excessive compatibilizer may deteriorate the mechanical properties of the polymer composite. Therefore, the compatibilizer is preferably contained in the polymer composite at 15 wt % or less, or 10 wt % or less. Specifically, the compatibilizer is contained in the polymer composite at 0.1 to 15 wt %, or 1 to 15 wt %, or 1 to 10 wt %, or 2.5 to 10 wt %.

[0099] According to an embodiment of the present invention, the polymer composite is obtained by mixing the above-mentioned components in a mixer and then curing them. Alternatively, the polymer composite may be prepared by preparing a fiber reinforcement mixture by mixing the first microcellulose fibers with the microcellulose fibers containing the nanofibrils and second inorganic particles, and then mixing the fiber reinforcement mixture with the polymer matrix. As a non-limiting example, the above-mentioned components may be mixed in a batch mixer at 100 to 180°C, followed by preparing a masterbatch in the form of pellets. The masterbatch may then be introduced into an extruder for extrusion and injection to obtain the polymer composite.

[0100] According to an embodiment of the present invention, the polymer composite contains the above-mentioned components, and thus is environmentally friendly and exhibits improved mechanical properties.

[0101] For example, the polymer composite may have an Izod impact strength of 30 J / m or more, measured on a notched 63.5 mm x 12.7 mm x 3.2 mm test specimen according to ASTM D256 standard (23°C, hammer head 3.00 J) in accordance with the standard test method of ASTM D256. Specifically, the polymer composite may have an Izod impact strength of 30 J / m or more, alternatively 32.5 J / m or more, or alternatively 35 J / m or more; and 300 J / m or less, alternatively 290 J / m or less, alternatively 280 J / m or less, or alternatively 275 J / m or less. Preferably, the polymer composite exhibits an Izod impact strength of 30 J / m to 300 J / m, alternatively 30 J / m to 290 J / m, alternatively 32.5 J / m to 290 J / m, alternatively 32.5 J / m to 280 J / m, alternatively 35 J / m to 280 J / m, alternatively 35 J / m to 275 J / m.

[0102] As another example, the polymer composite may have a tensile strength of 5 MPa or more, measured according to the standard test method of ASTM D638-5 on a dog-bone-shaped test specimen (or dumbbell-shaped specimen) made of the polymer composite. Preferably, the polymer composite may exhibit a tensile strength of 5 MPa to 45 MPa, or 5 MPa to 40 MPa, or 6 MPa to 40 MPa, or 6 MPa to 36 MPa.

[0103] ASTM D638 provides a standard test method for determining the tensile properties of plastics. Tensile properties for polymer composites are measured using ASTM D638 specimen type 5. ASTM D638 involves applying a tensile force to the specimen and measuring the tensile properties of the specimen under stress. This is done using a conventional tensile testing machine at a constant tensile rate ranging from 1 to 500 mm / min until the specimen breaks (yields or breaks). The tensile strength is the amount of force applied until the specimen yields or breaks.

[0104] As yet another example, the polymer composite may have a flexural strength of 50 MPa or more, measured on a test piece of the polymer composite measuring 80 mm x 10 mm x 4 mm according to the standard test method of ISO 178. Preferably, the polymer composite may exhibit a flexural strength of 5 MPa to 60 MPa, or 5 MPa to 55 MPa, or 8 MPa to 55 MPa, or 8 MPa to 50 MPa.

[0105] Furthermore, the polymer composite may have a flexural modulus of 0.1 GPa or more, measured on a test piece of the polymer composite measuring 80 mm x 10 mm x 4 mm in accordance with the standard test method of ISO 178. Preferably, the polymer composite may exhibit a flexural modulus of 0.1 GPa to 2.5 GPa, or 0.2 GPa to 2.5 GPa, or 0.2 GPa to 2.3 GPa, or 0.3 GPa to 2.3 GPa, or 0.3 GPa to 2.0 GPa.

[0106] ISO 178 provides a standard test method for determining flexural properties of plastics using a three-point bend test. A three-point bend test involves applying a force to the midpoint of a rectangular specimen supported freely at both ends. The applied force is measured by a load cell, and the resulting deflection is measured by crosshead displacement or a direct strain measurement device. This is performed using a conventional flexural tester, applying a force to the specimen at a constant rate ranging from 1 to 500 mm / min. The flexural strength is the maximum flexural stress achieved during the bend test. The flexural stress is measured by the flexural tester as a function of the applied load, span, specimen width, and specimen thickness.

[0107] As yet another example, the polymer composite may have an Izod impact strength of 30 J / m to 300 J / m, a tensile strength of 5 MPa to 45 MPa, and a flexural strength of 5 MPa to 60 MPa.

[0108] As yet another example, the polymer composite may have an Izod impact strength of 32.5 J / m to 280 J / m, a tensile strength of 6 MPa to 40 MPa, and a flexural strength of 8 MPa to 55 MPa.

[0109] As yet another example, the polymer composite may have an Izod impact strength of 35 J / m to 275 J / m, a tensile strength of 6 MPa to 36 MPa, and a flexural strength of 8 MPa to 50 MPa.

[0110] Meanwhile, according to another embodiment of the present invention, a molded article including a polymer composite is provided.

[0111] The molded article containing the polymer composite is environmentally friendly and exhibits excellent mechanical properties. Preferably, the molded article has an Izod impact strength of 30 J / m or more, measured according to the standard test method of ASTM D256 (23°C, hammer head 3.00 J).

[0112] The molded article can be produced by a conventional processing method using the polymer composite as a raw material, for example, by injection molding, extrusion molding, calendar molding, or the like using a raw material composition containing the polymer composite.

[0113] As an example, molded articles containing the polymer composite can be manufactured by injection molding. The polymer composite, which has been melted through the plasticization and flow stages, is injected into a mold cavity using a plunger, and then undergoes a cooling stage to solidify. The mold is equipped with a pressure sensor, a temperature sensor, a hot runner system, etc. A separate cooling line may be present to solidify the molten material. The plunger retracts, and the solidified molded article is separated from the mold using an ejector pin.

[0114] Preferably, the molded article may be a lightweight automotive material such as an automotive interior or exterior material, for example, one or more automotive interior or exterior materials selected from the group consisting of a dashboard, door trim, battery tray, bumper, luggage trim, door opening trim, headliner, rear shelf, tonneau cover, sun visor, assist grip, console box, fender panel, oil pan, wheel house, side skirt, garnish, electric parts, engine cover, seat belt cover, switch button, and center facia.

[0115] Furthermore, the molded product can be applied to various fields such as interior and exterior materials for home appliances and packaging materials. [Effects of the Invention]

[0116] The polymer composite according to the present invention contains cellulose fibers as a fiber reinforcement material, and is environmentally friendly and exhibits excellent mechanical properties and high brightness. [Brief explanation of the drawings]

[0117] [Figure 1] 1A and 1B are enlarged schematic views of (a) non-fibrillated microcellulose fibers and (b) microcellulose fibers containing nanofibrils and second inorganic particles. [Figure 2]1 is a scanning electron microscope (SEM) image of cellulose fibers fibrillated by the growth of second inorganic particles according to Preparation Example 2. [Figure 3] 1 is a scanning electron microscope (SEM) image of cellulose fibers fibrillated by the growth of second inorganic particles according to Preparation Example 2. [Figure 4] FIG. 1 is a comparative SEM image of (a) fibrillated microcellulose fibers according to Production Example 3 and (b) pulverized cellulose fibers composited with particles according to Production Example 4. [Figure 5] These are SEM images taken at a higher magnification than (a) and (b) in Figure 4. [Figure 6] FIG. 1 is a diagram showing the standard for dog-bone shaped test specimens (or dumbbell-shaped specimens) for tensile strength measurement according to ASTM D638 Type V (unit: mm). DETAILED DESCRIPTION OF THE INVENTION

[0118] The functions and effects of the present invention will be described in more detail below with reference to specific examples of the present invention, but these are presented as examples to aid in understanding the invention and do not in any way limit the scope of the invention.

[0119] Manufacturing Example 1 (First, preparation of microcellulose fibers) Hardwood kraft pulp (cellulose fiber) was prepared as a cellulose raw material. 20 g of the pulp was added to 1000 g of distilled water, and the mixture was crushed three times in a mixer in a wet state and then filtered under reduced pressure to prepare primary microcellulose fibers (diameters of 15 μm to 30 μm and lengths of 0.2 mm to 2 mm).

[0120] Manufacturing Example 2 (Production of second microcellulose fibers containing nanofibrils and second inorganic particles) Hardwood kraft pulp (cellulose fiber) was prepared as a cellulose raw material. An aqueous solution was prepared by dissolving 20 g of zinc acetate in 1000 g of distilled water. 20 g of the pulp was added to the aqueous solution and stirred at 500 rpm for 2 hours to obtain a mixture.

[0121] 7.2 g of sodium hydroxide (NaOH) was added as a reducing agent to the mixture at room temperature and stirred at 500 rpm for 2 hours to grow second inorganic particles (ZnO) on the pulp. The content of the second inorganic particles was confirmed to be 27 parts by weight per 100 parts by weight of the pulp.

[0122] Scanning electron microscope (SEM) observations confirmed that fibrillation had occurred in the pulp area where the second inorganic particles (ZnO) had grown, as shown in Figure 2(a). Analysis of the SEM image confirmed that the second inorganic particles had a particle size of approximately 0.1 μm to 1 μm.

[0123] In this manner, microcellulose fibers containing nanofibrils and second inorganic particles were obtained.

[0124] Manufacturing Example 3 (Production of second microcellulose fibers containing nanofibrils and second inorganic particles) Softwood kraft pulp fiber (cellulose fiber) was prepared as the cellulose raw material. 20 g of the pulp fiber was added to an aqueous solution of 20 g of zinc acetate dissolved in 1000 g of distilled water, and the mixture was stirred at 500 rpm for 2 hours to prepare a mixture. In the mixture, zinc acetate was attached to the swollen pulp fiber through hydrogen bonds and ionic bonds.

[0125] 3.6 g of sodium hydroxide (NaOH) was added to the mixture at room temperature and stirred at 500 rpm for 2 hours to grow second inorganic particles (ZnO) on the pulp fibers. The content of the second inorganic particles was confirmed to be 15 parts by weight per 100 parts by weight of the pulp.

[0126] As a result of examination using a scanning electron microscope, it was confirmed that fibrillation had occurred in the pulp fiber portions where particles (ZnO) had grown, as shown in Figure 4(a) and Figure 5(a).

[0127] In this manner, microcellulose fibers containing nanofibrils and second inorganic particles were obtained.

[0128] Production Example 4 (Production of micronized cellulose fibers) As a cellulose raw material, the same softwood kraft pulp fiber as in Example 1 was prepared. The surface of the pulp fiber was oxidized using 2,2,6,6-tetramethylpiperidinyl-1-oxy radical (TEMPO) as a catalyst to obtain oxidized pulp.

[0129] 1 g of the oxidized pulp was dispersed in 99 g of distilled water, and the dispersion was pulverized (defibrated) in a mixer for 30 minutes to obtain an aqueous dispersion of pulverized cellulose with a concentration of 1%.

[0130] A zinc acetate solution was prepared by dissolving 20 g of zinc acetate in 1000 g of distilled water. A sodium hydroxide solution was prepared by dissolving 3.6 g of sodium hydroxide (NaOH) in 10 ml of distilled water.

[0131] 100 g of the finely divided cellulose aqueous dispersion was stirred at 15°C while 50 ml of the zinc acetate aqueous solution and 10 ml of the sodium hydroxide aqueous solution were added, and the mixture was stirred at 500 rpm for 2 hours to produce a composite of zinc oxide (ZnO) particles and finely divided cellulose.

[0132] As a result of observation using a scanning electron microscope, as shown in Figure 4(b) and Figure 5(b), it was confirmed that the composite of zinc oxide particles and micronized cellulose obtained in Preparation Example 4 had poor particle dispersion due to the strong bonding and aggregation between the micronized cellulose, resulting in the nanofibers being clumped together.

[0133] Example 1 A batch mixer was charged with 20% by weight of the first microcellulose fiber according to Preparation Example 1, 10% by weight of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 45% by weight of polypropylene, and ethylene-butene rubber (density 0.865 g / cm 3 A masterbatch in pellet form was prepared by adding 10 wt% of MI (5.0 g / 10 min @ 190°C, 2.16 kg; manufactured by LG Chem), 5 wt% of titanium dioxide (average particle size 350 nm), and 10 wt% of a compatibilizer and mixing them at 180°C for 20 minutes. The compatibilizer used was maleic anhydride-grafted polypropylene.

[0134] The masterbatch was fed into a twin-screw extruder and compounded, and the resulting mixture was then fed back into an injector and injected to obtain polymer composite test pieces and molded articles (interior and exterior automotive materials).

[0135] Example 2 A batch mixer was charged with 20% by weight of the first microcellulose fiber according to Preparation Example 1, 10% by weight of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 35% by weight of polypropylene, and ethylene-butene rubber (density 0.865 g / cm). 3 Polymer composite test pieces and molded articles were obtained in the same manner as in Example 1, except that 20 wt. % of MI 5.0 g / 10 min (@190°C, 2.16 kg; manufactured by LG Chem), 5 wt. % of titanium oxide (average particle size 350 nm), and 10 wt. % of a compatibilizer were added.

[0136] Example 3 A batch mixer was charged with 20% by weight of the first microcellulose fiber according to Preparation Example 1, 10% by weight of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 25% by weight of polypropylene, and ethylene-butene rubber (density 0.865 g / cm). 3Polymer composite test pieces and molded articles were obtained in the same manner as in Example 1, except that 30 wt. % of MI 5.0 g / 10 min (@190°C, 2.16 kg; manufactured by LG Chem), 5 wt. % of titanium oxide (average particle size 350 nm), and 10 wt. % of a compatibilizer were added.

[0137] Example 4 Polymer composite test pieces and molded articles were obtained in the same manner as in Example 1, except that the second microcellulose fibers containing nanofibrils and second inorganic particles according to Preparation Example 3 were used instead of the second microcellulose fibers containing nanofibrils and second inorganic particles according to Preparation Example 2.

[0138] Example 5 A batch mixer was charged with 25% by weight of the first microcellulose fiber according to Preparation Example 1, 5% by weight of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 45% by weight of polypropylene, and ethylene-butene rubber (density 0.865 g / cm). 3 A masterbatch in pellet form was prepared by adding 10 wt% of MI (5.0 g / 10 min @ 190°C, 2.16 kg; manufactured by LG Chem), 5 wt% of titanium dioxide (average particle size 350 nm), and 10 wt% of a compatibilizer and mixing them at 180°C for 20 minutes. The compatibilizer used was maleic anhydride-grafted polypropylene.

[0139] The masterbatch was compounded and extruded in a twin-screw extruder, and the resulting mixture was then injected into an injector to obtain polymer composite test pieces and molded products (automobile luggage trim).

[0140] Example 6 A batch mixer was charged with 15% by weight of the first microcellulose fiber according to Preparation Example 1, 15% by weight of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 45% by weight of polypropylene, and ethylene-butene rubber (density 0.865 g / cm 3 Polymer composite test pieces and molded articles were obtained in the same manner as in Example 1, except that 10 wt % of MI 5.0 g / 10 min (@190°C, 2.16 kg; manufactured by LG Chem), 5 wt % of titanium oxide (average particle size 350 nm), and 10 wt % of a compatibilizer were added.

[0141] Example 7 A batch mixer was charged with 20% by weight of the first microcellulose fiber according to Preparation Example 1, 10% by weight of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 15% by weight of polypropylene, and ethylene-butene rubber (density 0.865 g / cm 3 Polymer composite test pieces and molded articles were obtained in the same manner as in Example 1, except that 40 wt. % of MI 5.0 g / 10 min (@190°C, 2.16 kg; manufactured by LG Chem), 5 wt. % of titanium oxide (average particle size 350 nm), and 10 wt. % of a compatibilizer were added.

[0142] Example 8 A batch mixer was charged with 20% by weight of the first microcellulose fiber according to Preparation Example 1, 10% by weight of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 5% by weight of polypropylene, and ethylene-butene rubber (density 0.865 g / cm 3 Polymer composite test pieces and molded articles were obtained in the same manner as in Example 1, except that 50 wt. % of MI 5.0 g / 10 min (@190°C, 2.16 kg; manufactured by LG Chem), 5 wt. % of titanium oxide (average particle size 350 nm), and 10 wt. % of a compatibilizer were added.

[0143] Example 9 Polymer composite test pieces and molded products were obtained in the same manner as in Example 1, except that 20 wt% of the first microcellulose fiber according to Preparation Example 1, 10 wt% of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 45 wt% of polypropylene, 10 wt% of ethylene-octene rubber (manufactured by LG Chemical), 5 wt% of titanium oxide (average particle size 350 nm), and 10 wt% of a compatibilizer were added to a batch mixer.

[0144] Example 10 Polymer composite test pieces and molded products were obtained in the same manner as in Example 1, except that 20 wt% of the first microcellulose fiber according to Preparation Example 1, 10 wt% of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 35 wt% of polypropylene, 20 wt% of ethylene-octene rubber (manufactured by LG Chemical), 5 wt% of titanium oxide (average particle size 350 nm), and 10 wt% of a compatibilizer were added to a batch mixer.

[0145] Example 11 Polymer composite test pieces and molded products were obtained in the same manner as in Example 1, except that 20 wt% of the first microcellulose fiber according to Preparation Example 1, 10 wt% of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 25 wt% of polypropylene, 30 wt% of ethylene-octene rubber (manufactured by LG Chemical), 5 wt% of titanium oxide (average particle size 350 nm), and 10 wt% of a compatibilizer were added to a batch mixer.

[0146] Example 12 Polymer composite test pieces and molded products were obtained in the same manner as in Example 1, except that 20 wt% of the first microcellulose fiber according to Preparation Example 1, 10 wt% of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 15 wt% of polypropylene, 40 wt% of ethylene-octene rubber (manufactured by LG Chemical), 5 wt% of titanium oxide (average particle size 350 nm), and 10 wt% of a compatibilizer were added to a batch mixer.

[0147] Example 13 Polymer composite test pieces and molded products were obtained in the same manner as in Example 1, except that 20 wt% of the first microcellulose fiber according to Preparation Example 1, 10 wt% of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 5 wt% of polypropylene, 50 wt% of ethylene-octene rubber (manufactured by LG Chemical), 5 wt% of titanium oxide (average particle size 350 nm), and 10 wt% of a compatibilizer were added to a batch mixer.

[0148] Example 14 A batch mixer was charged with 5% by weight of the first microcellulose fiber according to Preparation Example 1, 5% by weight of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 35% by weight of polypropylene, and ethylene-butene rubber (density 0.865 g / cm 3 Polymer composite test pieces and molded articles were obtained in the same manner as in Example 1, except that 40 wt. % of MI 5.0 g / 10 min (@190°C, 2.16 kg; manufactured by LG Chem), 5 wt. % of titanium oxide (average particle size 350 nm), and 10 wt. % of a compatibilizer were added.

[0149] Example 15 Polymer composite test pieces and molded products were obtained in the same manner as in Example 1, except that 5 wt% of the first microcellulose fiber according to Preparation Example 1, 5 wt% of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 35 wt% of polypropylene, 40 wt% of ethylene-octene rubber (manufactured by LG Chemical), 5 wt% of titanium oxide (average particle size 350 nm), and 10 wt% of a compatibilizer were added to a batch mixer.

[0150] Example 16 A batch mixer was charged with 30% by weight of the first microcellulose fiber according to Preparation Example 1, 15% by weight of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 20% by weight of polypropylene, and ethylene-butene rubber (density 0.865 g / cm 3 Polymer composite test pieces and molded articles were obtained in the same manner as in Example 1, except that 20 wt. % of MI 5.0 g / 10 min (@190°C, 2.16 kg; manufactured by LG Chem), 5 wt. % of titanium oxide (average particle size 350 nm), and 10 wt. % of a compatibilizer were added.

[0151] Example 17 Polymer composite test pieces and molded products were obtained in the same manner as in Example 1, except that 30 wt% of the first microcellulose fiber according to Preparation Example 1, 15 wt% of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 20 wt% of polypropylene, 20 wt% of ethylene-octene rubber (manufactured by LG Chemical), 5 wt% of titanium oxide (average particle size 350 nm), and 10 wt% of a compatibilizer were added to a batch mixer.

[0152] Example 18 A batch mixer was charged with 10% by weight of the first microcellulose fiber according to Preparation Example 1, 10% by weight of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 50% by weight of polypropylene, and ethylene-butene rubber (density 0.865 g / cm 3Polymer composite test pieces and molded articles were obtained in the same manner as in Example 1, except that 15 wt. % of MI 5.0 g / 10 min (@190°C, 2.16 kg; manufactured by LG Chem), 5 wt. % of titanium oxide (average particle size 350 nm), and 10 wt. % of a compatibilizer were added.

[0153] Example 19 Polymer composite test pieces and molded products were obtained in the same manner as in Example 1, except that 10 wt% of the first microcellulose fiber according to Preparation Example 1, 10 wt% of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 50 wt% of polypropylene, 15 wt% of ethylene-octene rubber (manufactured by LG Chemical), 5 wt% of titanium oxide (average particle size 350 nm), and 10 wt% of a compatibilizer were added to a batch mixer.

[0154] Example 20 A batch mixer was charged with 10% by weight of the first microcellulose fiber according to Preparation Example 1, 5% by weight of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 60% by weight of polypropylene, and ethylene-butene rubber (density 0.865 g / cm 3 Polymer composite test pieces and molded articles were obtained in the same manner as in Example 1, except that 10 wt % of MI 5.0 g / 10 min (@190°C, 2.16 kg; manufactured by LG Chem), 5 wt % of titanium oxide (average particle size 350 nm), and 10 wt % of a compatibilizer were added.

[0155] Example 21 Polymer composite test pieces and molded products were obtained in the same manner as in Example 1, except that 10 wt% of the first microcellulose fiber according to Preparation Example 1, 5 wt% of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 60 wt% of polypropylene, 10 wt% of ethylene-octene rubber (manufactured by LG Chemical), 5 wt% of titanium oxide (average particle size 350 nm), and 10 wt% of a compatibilizer were added to a batch mixer.

[0156] Example 22 A batch mixer was charged with 10% by weight of the first microcellulose fiber according to Preparation Example 1, 5% by weight of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 70% by weight of polypropylene, and ethylene-butene rubber (density 0.865 g / cm 3 Polymer composite test pieces and molded articles were obtained in the same manner as in Example 1, except that 5 wt. % of MI 5.0 g / 10 min (@190°C, 2.16 kg; manufactured by LG Chem), 5 wt. % of titanium oxide (average particle size 350 nm), and 5 wt. % of a compatibilizer were added.

[0157] Example 23 Polymer composite test pieces and molded products were obtained in the same manner as in Example 1, except that 10 wt% of the first microcellulose fiber according to Preparation Example 1, 5 wt% of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 70 wt% of polypropylene, 5 wt% of ethylene-octene rubber (manufactured by LG Chemical), 5 wt% of titanium oxide (average particle size 350 nm), and 5 wt% of a compatibilizer were added to a batch mixer.

[0158] Example 24 A batch mixer was charged with 7.5 wt% of the first microcellulose fiber according to Preparation Example 1, 5 wt% of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 80 wt% of polypropylene, and ethylene-butene rubber (density 0.865 g / cm). 3 Polymer composite test pieces and molded articles were obtained in the same manner as in Example 1, except that 2.5 wt% of MI 5.0 g / 10 min (@190°C, 2.16 kg; manufactured by LG Chem), 2.5 wt% of titanium oxide (average particle size 350 nm), and 2.5 wt% of a compatibilizer were added.

[0159] Example 25 Polymer composite test pieces and molded products were obtained in the same manner as in Example 1, except that 7.5 wt% of the first microcellulose fiber according to Preparation Example 1, 5 wt% of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 80 wt% of polypropylene, 2.5 wt% of ethylene-octene rubber (manufactured by LG Chemical), 2.5 wt% of titanium oxide (average particle size 350 nm), and 2.5 wt% of a compatibilizer were added to a batch mixer.

[0160] Example 26 A batch mixer was charged with 5% by weight of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 55% by weight of polypropylene, and ethylene-butene rubber (density 0.865 g / cm). 3 Polymer composite test pieces and molded articles were obtained in the same manner as in Example 1, except that 7.5 wt% of MI 5.0 g / 10 min (@190°C, 2.16 kg; manufactured by LG Chemical), 7.5 wt% of ethylene-octene rubber (manufactured by LG Chemical), 15 wt% of titanium oxide (average particle size 350 nm), and 10 wt% of a compatibilizer were added.

[0161] Example 27 A batch mixer was charged with 10% by weight of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 50% by weight of polypropylene, and ethylene-butene rubber (density 0.865 g / cm). 3 Polymer composite test pieces and molded articles were obtained in the same manner as in Example 1, except that 10 wt% of MI 5.0 g / 10 min (@190°C, 2.16 kg; manufactured by LG Chemical), 10 wt% of ethylene-octene rubber (manufactured by LG Chemical), 10 wt% of titanium oxide (average particle size 350 nm), and 10 wt% of a compatibilizer were added.

[0162] Example 28 A batch mixer was charged with 15% by weight of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 50% by weight of polypropylene, and ethylene-butene rubber (density 0.865 g / cm). 3 Polymer composite test pieces and molded articles were obtained in the same manner as in Example 1, except that 10 wt% of MI 5.0 g / 10 min (@190°C, 2.16 kg; manufactured by LG Chemical), 10 wt% of ethylene-octene rubber (manufactured by LG Chemical), 5 wt% of titanium oxide (average particle size 350 nm), and 10 wt% of a compatibilizer were added.

[0163] Example 29 A batch mixer was charged with 20% by weight of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 45% by weight of polypropylene, and ethylene-butene rubber (density 0.865 g / cm). 3 Polymer composite test pieces and molded articles were obtained in the same manner as in Example 1, except that 10 wt% of MI 5.0 g / 10 min (@190°C, 2.16 kg; manufactured by LG Chemical), 10 wt% of ethylene-octene rubber (manufactured by LG Chemical), 5 wt% of titanium oxide (average particle size 350 nm), and 10 wt% of a compatibilizer were added.

[0164] Comparative Example 1 Polymer composite test pieces and molded products were obtained in the same manner as in Example 1, except that 20 wt% of the first microcellulose fiber according to Preparation Example 1, 10 wt% of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 55 wt% of polypropylene, 5 wt% of titanium oxide (average particle size 350 nm), and 10 wt% of a compatibilizer were added to a batch mixer.

[0165] Comparative Example 2 Polymer composite test pieces and molded products were obtained in the same manner as in Example 1, except that 20 wt% of the first microcellulose fiber according to Preparation Example 1, 10 wt% of the second microcellulose fiber containing nanofibrils and second inorganic particles according to Preparation Example 2, 60 wt% of polypropylene, and 10 wt% of a compatibilizer were added to a batch mixer.

[0166] Comparative Example 3 Polymer composite test pieces and molded articles were obtained in the same manner as in Example 1, except that 30 wt % of the hardwood kraft pulp (cellulose fiber) used in Preparation Example 1, which had been swollen in water, 60 wt % of polypropylene, and 10 wt % of a compatibilizer were added to a batch mixer.

[0167] Comparative Example 4 Polymer composite test pieces and molded articles were obtained in the same manner as in Example 1, except that 30 wt% of the pulverized cellulose fiber prepared in Preparation Example 4, 60 wt% of polypropylene, and 10 wt% of the compatibilizer were added to a batch mixer.

[0168] Test Example (1) Fiber diameter The diameter of the cellulose fibers from the preparation examples was measured using a scanning electron microscope. Specifically, for microcellulose fibers, the diameters of 10 microfibers per sample were measured and expressed as a range excluding the maximum and minimum values; for nanofibrils, the diameters of 20 nanofibrils per sample were measured and expressed as a range excluding the maximum and minimum values.

[0169] Moreover, unlike the Examples, in Production Example 4, the pulp fibers were subjected to a micronization (defibration) process before being composited with particles, and in Table 1 below, the diameter of the nanofibrils in Production Example 4 refers to the diameter of the micronized cellulose after being composited with particles.

[0170] (2) Impact strength Test specimens with a notch measuring 63.5 mm × 12.7 mm × 3.2 mm according to ASTM D256 were prepared. The Izod impact strength of the test specimens was measured using a digital impact tester (QM (700A), manufactured by QMESYS) according to the standard test method of ASTM D256 (23°C, hammer head 3.00 J).

[0171] (3) Tensile test The following test specimens (Fig. 6) were prepared according to the ASTM D638 Type V standard. The test specimens were left in a constant temperature and humidity chamber maintained at 23°C and 50% relative humidity for 24 hours before being used for tensile testing.

[0172] The tensile strength (MPa), tensile modulus (GPa), and elongation at break (%) of the test specimens were measured using an Instron Universal Testing Machine (UTM) in accordance with the standard test method of ASTM D638. Based on the standard test method of ASTM D638, the grip spacing for holding the test specimens at both ends was set to 25.4 mm, and the test was carried out at a constant tensile speed of 5 mm / min at a crosshead speed.

[0173] (4) Bending test Test specimens with dimensions of 80 mm x 10 mm x 4 mm were prepared according to the standard test method of ISO 178. The test specimens were left in a constant temperature and humidity chamber adjusted to a temperature of 23°C and a relative humidity of 50% for 24 hours, and then subjected to a bending test.

[0174] The test specimens were measured for flexural strength (MPa), flexural modulus (GPa), and flexural deformation at break (%) using an Instron universal testing machine (UTM) in accordance with the standard test method of ISO 178. Based on ISO 178, a three-point bending test jig was used, with a support span set to 46 mm, and the bending test was carried out at a crosshead speed of 5 mm / min.

[0175] (5) Hue measurement The test specimens were measured for hue using a spectrophotometer (model name: Ci7860, manufacturer: X-rite) according to the L*a*b* (CIE LAB) color system. Test specimens measuring 63.5mm x 12.7mm x 3.2mm according to ASTM D256 were prepared, and measurements were taken three times in reflection mode, with the average value recorded.

[0176] [Table 1]

[0177] [Table 2]

[0178] [Table 3]

[0179] [Table 4]

[0180] [Table 5]

[0181] [Table 6]

[0182] [Table 7]

[0183] [Table 8]

[0184] Referring to Tables 2 to 8, it was confirmed that the polymer composites according to the examples exhibited superior impact strength and high brightness values ​​compared to the polymer composites according to the comparative examples.

[0185] Although the cellulose fibers produced in Preparation Example 4 had particles grown on the pulverized cellulose, excessive re-agglomeration of the pulverized cellulose and particles occurred when the fibers were composited with a polymer matrix in Comparative Example 4. The test specimens in Comparative Example 4, which showed poor dispersibility due to re-agglomeration, exhibited poor physical properties overall. [Explanation of symbols]

[0186] 100, 100' microcellulose fiber 11 Nanofibrils 20 Second inorganic particle

Claims

1. 5 to 90% by weight of a polymer matrix; 5 to 60% by weight of a fiber reinforcement material including cellulose fibers; 0.1 to 20% by weight of first inorganic particles containing one or more inorganic particles selected from the group consisting of titanium oxide, zinc oxide, boron nitride, and barium sulfate; comprising 1 to 60 wt. % of one or more rubbers selected from the group consisting of ethylene-butene rubber (EBR), ethylene-octene rubber (EOR), ethylene-propylene rubber (EPR), styrene-butadiene rubber (SBR), and nitrile-butadiene rubber (NBR); the cellulose fibers are microcellulose fibers containing nanofibrils and second inorganic particles; A polymer composite having an Izod impact strength of 30 J / m or more, measured in accordance with the standard test method of ASTM D256 (23°C, hammer head 3.00 J) on a notched test specimen of ASTM D256 standard size 63.5 mm x 12.7 mm x 3.2 mm.

2. The polymer composite according to claim 1 , wherein the first inorganic particles have an average particle size of 50 nm to 1000 nm.

3. The polymer composite of claim 1 satisfies the following formula 1: [Formula 1] L*≧90.0 In the above formula 1, the L* value is the lightness in the L*a*b* (CIE LAB) color system measured on a test piece made of the polymer composite using a spectrophotometer.

4. The polymer composite of claim 1 , wherein the nanofibrils are bonded to the surface of the microcellulose fibers; and the second inorganic particles are bonded to the nanofibrils or to the surface or interior of the microcellulose fibers.

5. 2. The polymer composite of claim 1, wherein the second inorganic particles comprise one or more metal particles selected from the group consisting of copper, zinc, calcium, aluminum, iron, platinum, palladium, ruthenium, iridium, rhodium, osmium, chromium, cobalt, nickel, manganese, vanadium, molybdenum, and gallium, or silicon oxide particles.

6. The polymer composite according to claim 1 , wherein the second inorganic particles are contained in an amount of 10 to 40 parts by weight based on 100 parts by weight of the microcellulose fibers.

7. 2. The polymer composite of claim 1, wherein the second inorganic particles include spherical particles having a diameter of 0.01 μm to 10 μm; columnar particles having one axis diameter of 0.01 μm to 10 μm and another axis diameter of 0.02 μm to 30 μm; or a mixture thereof.

8. 2. The polymer composite of claim 1, wherein the microcellulose fibers have a diameter of 1 μm to 30 μm and the nanofibrils have a diameter of 10 nm to 400 nm.

9. 10. The polymer composite of claim 1, wherein the cellulose fibers are a mixture of first microcellulose fibers and second microcellulose fibers comprising nanofibrils and second inorganic particles.

10. 10. The polymer composite of claim 9, wherein the first microcellulose fibers have a diameter of 10 μm to 40 μm and a length of 0.1 mm to 3 mm.

11. The polymer composite of claim 9, wherein the cellulose fibers comprise the first microcellulose fibers and second microcellulose fibers comprising the nanofibrils and second inorganic particles in a weight ratio of 1:0.1 to 1:

3.

12. 2. The polymer composite of claim 1, wherein the polymer matrix comprises one or more polymer resins selected from the group consisting of polyethylene, polyethylene-based copolymers, polypropylene, polypropylene-based copolymers, nylon-6, nylon-66, aramid, polystyrene, acrylonitrile-butadiene-styrene copolymers, styrene-maleic anhydride copolymers, styrene-acrylonitrile copolymers, styrene-butadiene-styrene copolymers, and polycarbonates.

13. 2. The polymer composite according to claim 1, wherein an ASTM D638-5 test piece made of the polymer composite has a tensile strength of 5 MPa or more, as measured in accordance with the standard test method of ASTM D638-5.

14. the polymer matrix and a fiber reinforcement material comprising the cellulose fibers; Izod impact strength of 35 J / m to 275 J / m, measured according to the standard test method of ASTM D256 (23°C, hammer head 3.00 J) on a notched test specimen of ASTM D256 standard size 63.5 mm x 12.7 mm x 3.2 mm; A tensile strength of 6 MPa to 36 MPa measured according to the standard test method of ASTM D638-5 on a test specimen of ASTM D638-5; and 10. The polymer composite of claim 1, having a flexural strength of 8 MPa to 50 MPa, measured according to the standard test method ISO 178 on a test specimen of 80 mm x 10 mm x 4 mm.

15. A molded article comprising the polymer composite of claim 1.

16. The molded article according to claim 15, which is an interior or exterior material for an automobile.

17. The molded products include dashboards, door trims, battery trays, bumpers, luggage trims, door opening trims, headliners, rear shelves, tonneau covers, sun visors, assist grips, console boxes, fender panels, oil pans, wheel houses, side skirts, garnishes, and electric parts.

16. The molded article according to claim 15, which is one or more automotive interior / exterior materials selected from the group consisting of seats, ...

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