Biofiller for resin reinforcement and resin composition comprising same

Abstract

The present invention provides: a resin reinforcing material comprising a vegetable-derived biofiller and a latex coating layer formed on the surface of the biofiller, wherein the latex coating layer includes a carboxyl group-containing conjugated diene-based rubber; a method for producing same; a resin composition comprising same; and a composite produced from the resin composition.

Description

Biofiller for resin reinforcement and resin composition containing the same

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2024-0114178, filed August 26, 2024, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a biofiller for reinforcing resin and a resin composition containing the same, and more particularly, to a biofiller having improved moisture vulnerability and physical properties through surface modification and a resin composition containing the same as a reinforcing material.

[0005] Recently, the production of composites using eco-friendly materials as reinforcing agents to improve the properties of polymer resins is increasing in various fields such as packaging materials, molded products, and various industrial materials.

[0006] For example, in the case of building materials and general household goods, composites, i.e. biocomposites, are being developed by dispersing wood powder in thermoplastic resins such as polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), acrylonitrile-butadiene-styrene (ABS), polyethylene terephthalate (PET), polylactic acid (PLA), and polybutylene adipate terephthalate (PBAT) and then extruding them. In addition to the processability, low price, and high surface strength of the polymer resin, the biocomposite has many advantages such as being environmentally friendly due to the use of plant-derived wood powder, improving the rigidity, which is a shortcoming of the polymer resin, and imparting a unique wood texture. Such biocomposites are also used in automobile interior and exterior materials and home appliances.

[0007] Additionally, composites using cellulose fibers are being developed to achieve weight reduction and increase recyclability instead of the high-density inorganic reinforcements previously used in other molded products.

[0008] Meanwhile, plant-derived biofillers, such as wood flour and cellulose fibers, used in the manufacture of eco-friendly composites, exhibit hydrophilic properties due to surface hydroxyl groups, making them vulnerable to moisture. Consequently, moisture penetration into products containing biofillers can cause swelling or swell, leading to dimensional changes. These biofillers also exhibit low compatibility with hydrophobic polymer resins due to their hydrophilic nature, which can reduce the interfacial bonding between different materials, resulting in deteriorated physical properties. Furthermore, biofillers are composed of highly crystalline polymers, making them hard and brittle, resulting in inadequate impact resistance.

[0009] Accordingly, biofillers used in resin compositions for manufacturing complexes are dried as much as possible to control moisture content, or compatibilizers are used to enhance the bonding strength between biofillers and polymer resins, and additives are used to enhance impact strength, but there are limitations in overcoming the moisture vulnerability and impact resistance of biofillers.

[0010] The present invention is intended to solve the problems mentioned in the background technology of the above invention, and provides a biofiller having improved properties such as moisture vulnerability and impact resistance through surface modification, a method for producing the same, and a resin composition and composite including the same as a reinforcing material.

[0011] According to one aspect of the present invention, a resin reinforcing material is provided, which comprises a plant-derived biofiller and a latex coating layer formed on the surface of the biofiller, wherein the latex coating layer comprises a carboxyl group-containing conjugated diene rubber.

[0012] According to another aspect of the present invention, a method for manufacturing a resin reinforcing material is provided, comprising the steps of (S1) adding a biofiller to a high-speed mixer and spraying a latex coating solution while stirring to form a latex coating layer on the surface of the biofiller; and (S2) drying and then compressing the biofiller on which the latex coating layer has been formed.

[0013] According to another aspect of the present invention, a resin composition comprising a polymer resin and a resin reinforcing material including a biofiller having a latex coating layer formed thereon, and a composite manufactured by extrusion molding the composition are provided.

[0014] According to the present invention, the moisture vulnerability of the biofiller can be overcome through chemical modification by forming a latex coating layer on the surface of the biofiller used as a resin reinforcing material and bonding the hydroxyl group present on the surface of the biofiller with the carboxyl group of the latex rubber.

[0015] In addition, when the latex-coated biofiller is mixed with a polymer resin to form a complex, the latex coating layer acts as a binder, thereby enhancing compatibility between the biofiller and the polymer resin and improving interfacial adhesion.

[0016] Additionally, by performing a compression process on the latex-coated biofiller, physical surface modification can be performed to remove micropores inside the biofiller, thereby improving physical properties, and granulation of the biofiller powder can be performed, thereby controlling the particle size in various ways, thereby maximizing process convenience and design effects during product manufacturing.

[0017] FIG. 1 schematically illustrates the particle shape of a biofiller included in a resin reinforcing material according to one embodiment of the present invention.

[0018] FIG. 2 shows high-temperature pressing of a latex-coated via filler in a method for manufacturing a resin reinforcing material according to one embodiment of the present invention.

[0019] Figure 3 shows the results of SEM-EDS analysis of the biofiller before and after surface modification.

[0020] Figure 4 illustrates a sheet-shaped specimen to which the composite manufactured in the examples and comparative examples is applied.

[0021] Figure 5 schematically illustrates the formation of a coating layer through a chemical reaction that forms an ester bond with a hydroxyl group present on the surface of a biofiller according to one embodiment of the present invention.

[0022] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0023] In addition, it should be understood that the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention, and therefore, there may be various equivalents and modified examples that can replace them at the time of filing this application.

[0024] In this application, each of the phrases "A or B", "at least one of A and B", "at least one of A or B", "A, B, or C", "at least one of A, B, and C", and "at least one of A, B, or C" may include any one of the items listed together in that phrase, or all possible combinations thereof.

[0025] As used herein, the term "and / or" includes any combination of a plurality of related described elements or any element among a plurality of related described elements.

[0026] In this specification, when a part is said to “include” or “contain” a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0027] One embodiment of the present invention relates to a resin reinforcing material comprising a plant-derived biofiller and a latex coating layer formed on the surface of the biofiller.

[0028] In the resin reinforcing material according to the present invention, the biofiller may include at least one selected from wood flour such as pine, spruce, acacia, and rubber tree as wood series; annual or perennial plant seeds such as kenaf, flax, hemp, jute, and bamboo; grains such as wheat and barley; shells obtained as by-products of food processing such as coconut shells and coffee grounds; and natural fibers such as cellulose and lignocellulose.

[0029] Specifically, the wood powder is made by crushing wood into small particles, drying it, and then turning it into powder.

[0030] The cellulose can be produced from wood-derived pulp, i.e., an aggregate of fibers having an outermost layer (primary wall) and multiple inner layers (secondary walls). For example, a microfiber cellulose powder obtained by dispersing the fiber aggregate in water and applying a shear force thereto and drying the fiber aggregate to remove water can be used.

[0031] These biofillers exhibit hydrophilicity due to the hydroxyl groups present on their surfaces, and can also form aggregates by forming hydrogen bonds between particles due to the hydroxyl groups. Therefore, the biofiller applied to the present invention may be a powder comprising primary particles and secondary particles formed by the aggregation of one or more primary particles by the hydroxyl groups, as shown in Fig. 1.

[0032] The above-mentioned biofiller in powder form can be used by classifying particles of a certain size using a mesh. For example, the biofiller powder applicable to the present invention can be composed of primary particles having an average size of 10 to 250 μm or 30 to 150 μm, and secondary particles formed by agglomeration of one or more of the primary particles and having an average size of 100 to 2,500 μm or 100 to 2,000 μm.

[0033] In the resin reinforcing material according to the present invention, the latex coating layer includes a carboxyl group-containing conjugated diene rubber, and can be formed on the surface of the primary particle of the biofiller and the surface of the secondary particle formed by agglomeration of one or more primary particles.

[0034] Specifically, the carboxyl group-containing conjugated diene rubber included in the latex coating layer may include at least one selected from carboxyl group-containing nitrile rubber (a1) such as acrylonitrile butadiene rubber (NBR), carboxyl group-containing styrene-butadiene rubber (SBR) (a2), carboxyl group-containing conjugated diene rubber (a3), etc.

[0035] The above carboxyl group-containing nitrile rubber (a1) may be manufactured by copolymerizing a conjugated diene monomer, an ethylenically unsaturated carboxylic acid monomer, and an ethylenically unsaturated nitrile monomer.

[0036] Examples of the above conjugated diene monomer include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 1,3-pentadiene, and chloroprene, and such conjugated diene monomer units may be included in an amount of 50 to 80 wt% or 55 to 70 wt% based on the total weight of the carboxyl group-containing nitrile rubber.

[0037] Examples of the above ethylenically unsaturated carboxylic acid monomers include acrylic acid, methacrylic acid, etc. The content of such ethylenically unsaturated carboxylic acid monomer units may be included in an amount of 2 to 10 wt% or 2 to 6 wt% based on the total weight of the carboxyl group-containing nitrile rubber, and the content may be changed depending on the physical properties required in the field.

[0038] Examples of the above ethylenically unsaturated nitrile monomers include acrylonitrile, methacrylonitrile, fumaronitrile, α-chloroacrylonitrile, α-cyanoethylacrylonitrile, etc. These ethylenically unsaturated nitrile monomer units may be included in an amount of 10 to 40 wt% or 20 to 40 wt% based on the total weight of the carboxyl group-containing nitrile rubber, and the content may be changed depending on the properties required in the field.

[0039] In addition, the above carboxyl group-containing nitrile rubber may additionally include other ethylenically unsaturated monomers copolymerizable with the above monomers (e.g., amide-containing monomers, epoxy-containing monomers, etc.).

[0040] In addition, the carboxyl group-containing styrene-butadiene rubber (a2) may be manufactured by copolymerizing a conjugated diene monomer such as 1,3-butadiene, an ethylenically unsaturated carboxylic acid monomer, and styrene, and may additionally include other ethylenically unsaturated monomers copolymerizable with these. The content of the monomers may be appropriately selected depending on the physical properties required in the field.

[0041] The above carboxyl group-containing conjugated diene rubber (a3) ​​may be manufactured by copolymerizing a conjugated diene monomer and an ethylenically unsaturated carboxylic acid monomer, and may additionally include other ethylenically unsaturated monomers copolymerizable with these monomers. The content of the monomers may be appropriately selected depending on the physical properties required in the field.

[0042] The latex of the rubber component as described above has a carboxyl group, and thus can form a coating layer through a chemical reaction that forms an ester bond with the hydroxyl group present on the surface of the biofiller, as shown in Fig. 5.

[0043] When the surface of a biofiller is chemically modified through ester bonding with latex, a rubber component, the latex coating layer formed on the surface of the biofiller can impart moisture barrier properties. Therefore, products containing latex-coated biofillers exhibit reduced moisture penetration even when exposed to moisture, thereby suppressing dimensional changes due to swelling or swell.

[0044] In addition, the latex coating layer can improve interfacial adhesiveness by promoting compatibility between the biofiller and the polymer resin by acting as a binder when the biofiller is mixed with the polymer resin to form a complex, thereby improving the physical properties of the product to which the biofiller is applied.

[0045] In addition, as the particle size of the biofiller increases due to the formation of the latex coating layer, a product that uses it as a reinforcing material can exhibit excellent impact strength due to improved resistance to absorbing impact when subjected to impact.

[0046] In one embodiment of the present invention, the latex coating layer may be formed in the form of a thin film surrounding the primary particles or secondary particles of the biofiller through a spray coating method. For example, the latex coating layer may be formed to a thickness of 0.2 to 50 ㎛ or 0.25 to 40 ㎛. If the thickness of the coating layer is less than 0.2 ㎛, it may be difficult to improve the moisture barrier property of the biofiller and compatibility with the polymer resin, and if it exceeds 50 ㎛, the dispersion of the coating solution may be reduced, resulting in a deterioration in physical properties.

[0047] The particle size of such latex-coated biofiller may range from 0.1 to 10 mm or from 1 to 10 mm. If the average particle size of the latex-coated biofiller is less than 0.1 mm, the effect of improving impact strength as a reinforcing material may be insufficient, and if it exceeds 10 mm, uniform dispersion may be difficult when included in a composite.

[0048] If necessary, the resin reinforcing material may additionally include additives such as crosslinking agents, dispersants, stabilizers, thickeners, lubricants, and antioxidants to improve physical properties, and the content thereof may be appropriately selected within a range that does not impair the inherent performance of the resin reinforcing material.

[0049] Another embodiment of the present invention relates to a method for manufacturing the resin reinforcing material, the method comprising: (S1) a step of introducing a biofiller into a high-speed mixer and spraying a latex coating solution while stirring to form a latex coating layer on the surface of the biofiller; and (S2) a step of drying and then compressing the biofiller on which the latex coating layer has been formed.

[0050] In the above step (S1), the biofiller may include at least one selected from wood powder of pine, spruce, acacia or rubber tree; plants of kenaf, flax, hemp, jute or bamboo seeds; grains of wheat or barley; husks of coconut shells or coffee grounds; and natural fibers of cellulose or lignocellulose, and specifically, powder ground into small particles and dried to have a moisture content of less than 10% may be used.

[0051] In one embodiment of the present invention, the biofiller powder may be composed of primary particles having an average size of 10 to 250 μm or 30 to 150 μm, particles passing through 10 to 500 mesh, 10 to 200 mesh, or 10 to 60 mesh, and secondary particles formed by agglomeration of one or more of the primary particles and having an average size of 100 to 2,500 μm or 100 to 2,000 μm.

[0052] Meanwhile, the latex coating solution can be prepared by dispersing the carboxyl group-containing conjugated diene rubber described above in water.

[0053] At this time, the carboxyl group-containing conjugated diene rubber may be used in an amount of 0.5 to 30 wt% or 10 to 30 wt% based on the weight of the biofiller. If the content of the carboxyl group-containing conjugated diene rubber is less than 0.5 wt%, the effect of imparting moisture barrier properties to the biofiller and improving compatibility with the polymer resin is insufficient, and if it exceeds 30 wt%, the increase in the rubber component may cause difficulty in dispersion and deterioration in physical properties.

[0054] If necessary, the latex coating solution may additionally contain a crosslinking agent, a dispersing agent, a stabilizer, a thickener, etc.

[0055] Such latex coating solution can be coated on the surface of the biofiller by spraying it using a spray device. Specifically, the coating can be performed by placing the biofiller in a high-speed mixer, stirring it, spraying the latex coating solution through the spray nozzle of the spray device, and then maintaining the mixture for a certain period of time (e.g., 1 to 5 minutes or 2 to 3 minutes) to allow a chemical reaction between the biofiller and the latex.

[0056] This spray-type coating method can form a thin-film coating layer surrounding the surface of the biofiller particles by uniformly spraying the latex coating solution onto the surface of the biofiller. Furthermore, as the particle size of the biofiller increases due to the formation of the latex coating layer, impact strength can be improved during product application.

[0057] In one embodiment of the present invention, the stirring may be performed at a speed of 500 to 1,500 rpm or 800 to 1,200 rpm for stable operation of the high-speed mixer.

[0058] In the above step (S2), the biofiller on which the latex coating layer is formed is dried to remove moisture, and then can be compressed by putting it into a compression device such as a press jig and applying pressure at high temperature.

[0059] The drying can be performed at 50 to 120°C or 70 to 90°C for 2 to 5 hours or 3 to 4 hours.

[0060] The above high-temperature pressing can be performed using pressing equipment such as a press, a roll mill, or a pellet mill, and can implement physical surface modification that induces chain anchoring by applying physical force while the rubber component of the latex is chemically bonded to the surface of the biofiller. If pressing is not performed after latex coating, clumping may occur in the coating layer, making it difficult to implement an increase in particle size due to the coating.

[0061] In addition, the bulk density can be increased by removing micropores inside the biofiller through the high-temperature pressing, and this enables the application of a high content of biofiller when forming a complex with a polymer resin, thereby improving physical properties.

[0062] In addition, granulation of biofiller powder is possible through high-temperature pressing, allowing for a variety of particle size adjustments, thereby maximizing process convenience and design effects during product manufacturing.

[0063] In one embodiment of the present invention, the pressing may be performed at a temperature of 70 to 250° C. or 100 to 230° C. and a pressure of 10 to 70 bar or 10 to 50 bar for 1 to 5 minutes or 2 to 4 minutes. If the pressure during the pressing is less than 5 bar, it may be difficult to achieve the intended physical surface modification of the biofiller, and if it exceeds 70 bar, carbonization of the latex and biofiller may occur.

[0064] A biofiller having a latex coating layer formed by the above method can be used together with a polymer resin as a resin reinforcing material.

[0065] Accordingly, another embodiment of the present invention relates to a resin composition comprising a resin reinforcing material including a polymer resin and a biofiller having a latex coating layer formed thereon.

[0066] The polymer resin may include at least one selected from thermoplastic resins including polylactic acid (PLA), polybutylene adipate (PBAT), polyethylene (PE), polypropylene (PP), acrylonitrile-butadiene-styrene (ABS), polyvinyl chloride (PVC), polyethylene terephthalate (PET) or mixtures thereof; and thermosetting resins including epoxy resins, amino resins, phenol resins, polyester resins, polyurethane resins or mixtures thereof.

[0067] The polymer resins mentioned above are used in the manufacture of various molded products due to their characteristics such as processability, low cost, and high surface strength. Biofillers are also emerging as resin reinforcement materials due to their environmentally friendly nature. However, due to their moisture vulnerability, exposure to high temperature and humidity can cause dimensional deformation, poor compatibility with hydrophobic polymers, and poor impact resistance, which can lead to deterioration of mechanical properties.

[0068] To overcome these shortcomings, the present invention uses a biofiller having a latex coating layer formed as a reinforcing material forming a composite with the polymer resin, and as the biofiller is surface-modified with latex, its compatibility and bonding strength with the hydrophobic polymer resin, as well as its impact resistance, can be improved, thereby improving the physical properties of the composite.

[0069] In a resin composition according to one embodiment of the present invention, a biofiller having a latex coating layer formed thereon may be included in an amount of 1 to 40 wt% or 5 to 20 wt% based on the total weight of the composition. If the content of the biofiller is less than 1 wt%, it may be difficult to sufficiently function as a reinforcing material, and if it exceeds 40 wt%, it may be difficult to form a product due to reduced fluidity.

[0070] If necessary, the resin composition may include additives such as a compatibilizer, antioxidant, lubricant, pigment, etc. commonly used in the field, and the content thereof may be appropriately selected within a range that implements the desired physical properties.

[0071] The above resin composition can be manufactured into a composite through processes such as extrusion, injection, etc., and used for various purposes such as packaging materials, building materials, automobile interior and exterior materials, and home appliances.

[0072] Hereinafter, to aid understanding of the present invention, examples will be described in detail. However, the embodiments according to the present invention may be modified in various ways, and the scope of the present invention should not be construed as being limited to the following examples. These examples are provided to more fully explain the present invention to those of average skill in the art.

[0073] Manufacturing example: Manufacturing of resin reinforcement

[0074] Manufacturing Example 1

[0075] (Step 1)

[0076] Pine tree powder sieved through 60 mesh as a biofiller was prepared and dried in an 80°C oven for approximately 24 hours. 120 g of the dried pine tree powder was placed in a high-speed mixer and the stirring speed was slowly increased to 1,000 rpm.

[0077] Meanwhile, 90 g of a latex coating solution containing acrylonitrile rubber (NBR) dispersed in water was prepared and sprayed onto the operating high-speed mixer using a spraying device. At this time, the NBR was used at 10 wt% based on the weight of the biofiller. Thereafter, the high-speed mixer was continuously operated for 3 minutes to ensure uniform mixing, thereby forming an NBR latex coating layer and obtaining a surface-modified biofiller powder.

[0078] (Step 2)

[0079] The NBR latex-coated biofiller powder was dried in an 80°C oven for approximately 3 hours to remove moisture. 30 g of the dried powder was weighed, inserted into a press jig, and pressed under pressure for 3 minutes at 200°C and 10 bar, as shown in Fig. 2. Thus, the biofiller surface-modified by latex coating and pressing was manufactured into a resin reinforcing material.

[0080] Figure 3 shows the SEM-EDS analysis results for the biofiller (a) before surface modification and the biofiller (b) after surface modification as in Manufacturing Example 1.

[0081] From Fig. 3, it can be confirmed that the particle size of the biofiller (b) after surface modification increases compared to that before modification (a) due to the formation of an NBR latex coating layer.

[0082] Manufacturing Example 2

[0083] A resin reinforcing material was manufactured by performing the same process as in Manufacturing Example 1, except that the pressing was performed at 50 bar in Step 2.

[0084] Manufacturing Example 3

[0085] A resin reinforcing material was manufactured by performing the same process as Manufacturing Example 1, except that NBR was used at 30 wt% based on the weight of the biofiller in Step 1 and compression was performed at 50 bar in Step 2.

[0086] Comparative Manufacturing Example 1

[0087] A resin reinforcing material of biofiller powder was manufactured by performing the same process as in Manufacturing Example 1 except that the pressing in Step 2 was not performed, and only chemical surface modification was performed by forming an NBR latex coating layer.

[0088] Comparative Manufacturing Example 2

[0089] Pine powder sieved through 60 mesh as a biofiller was prepared and dried in an 80°C oven for approximately 24 hours. 30 g of the dried powder was weighed, inserted into a press jig, and pressed under pressure for 3 minutes at 200°C and 50 bar as shown in Fig. 2. Thus, a resin reinforcing material of biofiller powder with only physical surface modification was manufactured.

[0090] Example: Preparation of a resin composition containing a resin reinforcing material

[0091] Example 1

[0092] A resin composition was obtained by mixing 90 wt% of a polymer resin in which polylactic acid (PLA) and polybutylene adipate (PBAT) were mixed in a weight ratio of 1:1 and 10 wt% of the resin reinforcing material of Manufacturing Example 1.

[0093] The above resin composition was fed into a twin screw extruder and extruded under the conditions of 170°C, 250 rpm, and 15 kg / hr to produce a pellet-shaped composite.

[0094] Example 2

[0095] A pellet-shaped composite was manufactured by performing the same process as Example 1, except that the PLA / PBAT (1:1) polymer resin was mixed with the resin reinforcing material of Manufacturing Example 2.

[0096] Example 3

[0097] A pellet-shaped composite was manufactured by performing the same process as Example 1, except that the PLA / PBAT (1:1) polymer resin was mixed with the resin reinforcing material of Manufacturing Example 3.

[0098] Comparative Example 1

[0099] A pellet-shaped composite was manufactured by performing the same process as Example 1, except that the PLA / PBAT (1:1) polymer resin was mixed with a non-surface-modified biofiller (pine powder sieved through 60 mesh) as a resin reinforcing material.

[0100] Comparative Example 2

[0101] A pellet-shaped composite was manufactured by performing the same process as Example 1, except that the PLA / PBAT (1:1) polymer resin was mixed with the resin reinforcing material of Comparative Manufacturing Example 1.

[0102] Comparative Example 3

[0103] A pellet-shaped composite was manufactured by performing the same process as Example 1, except that the PLA / PBAT (1:1) polymer resin was mixed with the resin reinforcing material of Comparative Manufacturing Example 2.

[0104] Experimental example: Physical property evaluation

[0105] <Moisture absorption rate>

[0106] Each biofiller used as a resin reinforcing material in the above examples and comparative examples was exposed for 8 hours under conditions of 40°C and 95% relative humidity, and then the rate of change in the initial weight (W1) and the weight after exposure (W2) was measured according to the following equation to evaluate the moisture absorption rate.

[0107] Moisture absorption (%) = (W2-W1) / W1Х100

[0108] Melting index

[0109] For the composites manufactured in the above examples and comparative examples, the melt index (MI) was measured according to ASTM D1238 using a 2.16 kg weight at 190°C.

[0110]

[0111] Mechanical properties

[0112] The composites manufactured in the above examples and comparative examples were used to manufacture specimens with a thickness of 3.2 mm and a thickness of 6.4 mm using a hot press, and the IZOD impact strength of each specimen was measured according to ASTM D256.

[0113] Properties of resin-reinforced composites Chemical surface modification Physical surface modification Moisture absorption (%) M I Z O D (kgf cm / cm ) I Z O D (kgf cm / cm ) 6.4 mm 3.2 mm Example 1 Latex 10% coating 10 bar compression 62.2 11 17 Example 2 Latex 10% coating 50 bar compression 52.3 13 19 Example 3 Latex 30% coating 50 bar compression 32.3 15 25 Comparative Example 1 - 101.6 11 16 Comparative Example 2 Latex 10% coating - 92.3 10 14 Comparative Example 3 - 50 bar compression 9.5 1.3 11 17

[0114] In the above Table 1, it can be confirmed that the biofillers with chemical and physical surface modifications through latex coating and pressing in Examples 1 to 3 had a reduced water absorption rate, thereby improving moisture vulnerability, and the composites using them as resin reinforcing materials had a high melt index and improved IZOD impact strength. In particular, Example 3 had the best IZOD impact strength as the amount of latex coating increased to 30 wt% during chemical surface modification. These results are expected to be due to the fact that the latex coating increased the compatibility between the biofiller and the polymer resin, thereby improving the bonding strength and increasing the melt index, and increasing the impact strength by increasing the particle size. In contrast, Comparative Example 1 had an increased water absorption rate because the biofiller was not surface modified, and the composite using such a biofiller had a low melt index and IZOD impact strength.

[0115] Comparative Example 2 showed insufficient improvement in water absorption rate as only chemical surface modification of the latex coating on the biofiller was performed. The composite using such biofiller had a comparable melt index compared to Example 1, but a reduced IZOD impact strength.

[0116] Comparative Example 3 showed that the moisture absorption rate increased as only physical surface modification by compression was performed on the biofiller, and the composite using such biofiller showed a reduced melting index and similar IZOD impact strength compared to Example 2.

[0117] In addition, Fig. 4 illustrates sheet-shaped specimens using the composites manufactured in Examples and Comparative Examples. Specimen (#1) is a composite of Comparative Example 1 using a biofiller that has not been surface-modified as a resin reinforcing material, and exhibits an appearance of wood powder color. Specimen (#2) is a composite of Comparative Example 2 using a biofiller that has only been chemically surface-modified, and although the wood powder color has become darker due to the NBR coating, since no pressing was performed after coating, the particle size control was insufficient, and thus exhibits an appearance similar to Comparative Example 1. In contrast, Specimens (#3) to (#5) are composites of Examples 1 to 3 using a biofiller that has been chemically and physically surface-modified, and exhibit an appearance in which a speckle pattern design is implemented due to an increase in particle size. That is, the latex-coated biofiller according to the present invention can be variously controlled in particle size to impart a design effect preferred by customers when used as a resin reinforcing material.

Claims

It comprises a plant-derived biofiller and a latex coating layer formed on the surface of the biofiller, The above latex coating layer is a resin reinforcing material including a carboxyl group-containing conjugated diene rubber. In the first paragraph, The biofiller is a resin reinforcing material comprising at least one selected from wood flour of pine, spruce, acacia or rubber trees; plants of kenaf, flax, hemp, jute or bamboo seeds; grains of wheat or barley; husks of coconut shells or coffee grounds; and natural fibers of cellulose or lignocellulose. In the first paragraph, A resin reinforcing material comprising at least one selected from carboxyl group-containing nitrile rubber, carboxyl group-containing styrene-butadiene rubber, and carboxyl group-containing conjugated diene rubber contained in the latex coating layer. In the first paragraph, The above biofiller comprises primary particles and secondary particles formed by agglomeration of one or more primary particles, The above latex coating layer is a resin reinforcing material formed on the surface of the primary particle and the surface of the secondary particle. In paragraph 4, The primary particles of the above biofiller have an average particle diameter of 10 to 250 ㎛, The secondary particles of the above biofiller are resin reinforcing materials having an average particle diameter of 100 to 2,500 ㎛. In the first paragraph, The above latex coating layer is a resin reinforcing material formed on the surface of the biofiller with a thickness of 0.2 to 50 ㎛. In the first paragraph, A resin reinforcing material comprising the above biofiller and a latex coating layer formed on the surface thereof, wherein the average particle diameter of the resin reinforcing material is in the range of 0.1 to 10 mm. (S1) A step of forming a latex coating layer on the surface of the biofiller by spraying a latex coating solution while adding the biofiller to a high-speed mixer and stirring; and (S2) A method for manufacturing a resin reinforcing material, comprising the step of drying and then compressing a biofiller having the latex coating layer formed thereon. In paragraph 8, The above latex coating liquid contains a carboxyl group-containing conjugated diene rubber, A method for producing a resin reinforcing material, wherein the above carboxyl group-containing conjugated diene rubber is used in an amount of 0.5 to 30 wt% based on the weight of the biofiller. In paragraph 8, A method for producing a resin reinforcement material, wherein the above stirring is performed at 500 to 1,500 rpm. In paragraph 8, A method for producing a resin reinforcement material, wherein the above pressing is performed at a temperature of 70 to 250°C and a pressure of 10 to 70 bar. A resin composition comprising a resin reinforcing material including a polymer resin and a biofiller having a latex coating layer formed thereon. In Article 12, A resin composition in which the above resin reinforcing material is included in an amount of 1 to 40 wt% based on the total weight of the composition. In Article 12, The polymer resin is a resin composition comprising at least one selected from thermoplastic resins including polylactic acid (PLA), polybutylene adipate (PBAT), polyethylene (PE), polypropylene (PP), acrylonitrile-butadiene-styrene (ABS), polyvinyl chloride (PVC), polyethylene terephthalate (PET) or mixtures thereof; and thermosetting resins including epoxy resins, amino resins, phenol resins, polyester resins, polyurethane resins or mixtures thereof. A composite manufactured by extrusion molding a resin composition according to Article 12.

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