Filler, resin composition, and method for producing filler

Abstract

This invention provides a filler that contains cellulose and can form a lightweight composite material with excellent strength. [Solution] A filler for compounding with resin, comprising particles mainly containing cellulose, wherein the cellulose located on the surface of the particles is derivatized, and the apparent density of the particles is 1.0 g / cm³. 3 The following are fillers.

Description

[Technical Field]

[0001] This invention relates to fillers, resin compositions, and methods for producing fillers. [Background technology]

[0002] As an attempt to replace petroleum-derived materials with natural materials, development is underway to add wood-derived cellulose as a filler to plastics.

[0003] For example, Patent Document 1 discloses a fiber-reinforced resin composition having a specific chemical structure, which is a composite of chemically modified microfibrillated cellulose fibers obtained by wet defibration of pulp and then esterification, an inorganic filler, and a thermoplastic resin. The aim is to obtain a lightweight fiber-reinforced resin composition and a molded article thereof with excellent strength properties. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2019-006997 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, plastic composites with cellulose added as a filler had the problem of insufficient strength due to the low compatibility of the interface between the plastic and cellulose, which made the interface prone to fracture. In addition, compounding resin and cellulose tends to increase density, so there was a demand for lighter composite materials. [Means for solving the problem]

[0006] One embodiment of the filler according to the present invention is: A filler for compounding with resin, It consists of particles that mainly contain cellulose, The cellulose located on the surface of the particles is derivatized, the particles have an apparent density of 1.0 g / cm 3 or less.

[0007] One aspect of the resin composition according to the present invention is comprising the above filler and the resin.

[0008] One aspect of the method for producing the filler according to the present invention is a pulverization step of pulverizing cellulose to obtain cellulose particles having pores; and a derivatization step of derivatizing said particles in a liquid to derivatize cellulose located on the surface and outer edge of said particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] [Figure 1] Table 1 showing the results of experimental examples. MODES FOR CARRYING OUT THE INVENTION

[0010] Embodiments of the present invention are described below. The embodiments described below illustrate examples of the present invention. The present invention is not limited to the following embodiments, and also includes various modifications implemented within the scope not altering the gist of the present invention. Note that not all of the configurations described below are necessarily essential configurations of the present invention.

[0011] In the present specification, a numerical range expressed using "~" means a range including the numerical values described before and after "~" as the lower limit and the upper limit.

[0012] 1. Filler The filler according to the present embodiment is a filler for compounding with a resin, and consists of particles containing cellulose as a main component, the cellulose located on the surface of the particles is derivatized, and the apparent density of the particles is 1.0 g / cm 3 or less.

[0013] 1.1. Particles The filler according to this embodiment consists of particles mainly composed of cellulose. The filler can be handled as a powder consisting of a large number of particles. When the filler is viewed as a powder of particles, it may have a particle size distribution. The average particle size of the filler powder is, for example, 3 μm to 400 μm, preferably 5 μm to 150 μm, and more preferably 10 μm to 80 μm. The particle size distribution of the filler powder can be measured, for example, using a particle size analyzer that uses dynamic light scattering as its measurement principle (e.g., "Microtrac UPA" manufactured by Nikkiso Co., Ltd.).

[0014] When referring to the cellulose content in particles, the amount of cellulose refers to the sum of unmodified cellulose and the derivatized cellulose described later. In terms of being the main component, the cellulose content in particles should be 55% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0015] 1.1.1. Cellulose The cellulose raw material that forms the particles is not particularly limited as long as it contains cellulose. Examples of cellulose raw materials include pulp (sheets and bales of hardwoods, softwoods, kenaf, bagasse, kapok, etc.), kraft pulp, dissolved pulp, sulfite pulp, paper (copy paper, printing paper, cardboard, etc.), recycled paper, tissue paper, kitchen paper, cleaners, filters, liquid absorbents, sound absorbers, cushioning materials, mats, corrugated cardboard, etc. Multiple types of cellulose raw materials listed above may be used. Furthermore, cellulose raw materials that have undergone bleaching or other treatments may be used. Among these, dissolved pulp is more preferable as the raw material for the filler in this embodiment because its high cellulose purity allows for higher purity of the derivative.

[0016] Particles mainly composed of cellulose can be obtained by grinding cellulose raw materials. The grinding of cellulose raw materials will be described later. In the state after grinding the cellulose raw material, that is, before derivatization as described later, the ground particles have pores (open pores) and internal voids (closed pores) throughout. In this specification, "particles mainly composed of cellulose" may be simply referred to as "cellulose particles."

[0017] Cellulose is a plant-derived, abundant natural material that can more effectively address environmental issues and conserve resources. It is also preferable from the standpoint of supplying composites manufactured using cellulose and reducing costs. Furthermore, cellulose has particularly high theoretical strength among various materials, which is advantageous from the standpoint of further improving the strength of composites and molded products. In addition, cellulose has good biodegradability.

[0018] 1.1.2. Derivatization The cellulose located on the surface of the cellulose-based particles described above is derivatized. Cellulose can be derivatized by esterification, etherification, etc. In the cellulose-based particles that constitute the filler of this embodiment, at least the cellulose located on the surface is derivatized.

[0019] The following equation (1) is an example of a reaction equation showing esterification, which is an example of derivatization of cellulose. [ka]

[0020] In the above equation (1), R 1 represents a saturated or unsaturated alkyl group with 2 to 20 carbon atoms, and consists of three R's. 2 At least one of them represents a saturated or unsaturated alkylcarbonyl group having 2 to 20 carbon atoms, and the remaining R 2 This represents hydrogen.

[0021] In the above formula (1), R is used as the esterifying agent. 1-CH2-(C=O)-Cl is used, but R 1 of a plurality of mutually different types of R 1 -CH2-(C=O)-Cl may be used. And R which is a saturated or unsaturated alkylcarbonyl group having 2 to 20 carbon atoms 2 when two or more are formed, these may be the same or different.

[0022] As shown in the above formula (1), cellulose is reacted with an acid chloride in a solvent (in the example of formula (1), N-methylpyrrolidone (NMP) and pyridine), whereby part or all of the hydroxyl groups are esterified. In this case, the acid chloride serves as an esterifying agent.

[0023] When derivatization is performed by etherification, examples of the etherifying agent include alkyl halides, and etherification of cellulose can be performed in an appropriate solvent.

[0024] Cellulose particles are derivatized in a solvent, whereby at least the cellulose present on the surface is derivatized. Further, pulverized cellulose particles have pores and internal voids, and cellulose existing closer to the inside than the surface can also be derivatized by the derivatizing agent that has penetrated into the pores.

[0025] Cellulose expands in volume due to derivatization. As a result, the pores of the cellulose particles are narrowed or blocked. This makes it difficult for the derivatizing agent to penetrate into the interior of the cellulose particles, leaving pores and internal voids near the center of the cellulose particles. In other words, the outer edge portion of the cellulose particles is derivatized, and the inner side thereof is less likely to be derivatized.

[0026] Here, the outer edge refers to the shell-like portion extending 50% from the surface of the cellulose particle toward the center, preferably 30%, and more preferably 10%, assuming the cellulose particle is a sphere. If the cellulose particle is amorphous, the center of gravity may be considered the center, and the outer edge similarly refers to the shell-like portion extending 50% from the surface of the cellulose particle toward the center of gravity, preferably 30%, and more preferably 10%.

[0027] Cellulose located on the surface of cellulose particles tends to have a higher degree of substitution through derivatization than cellulose located at the outer edge of the cellulose particles. This makes it easier for pores and internal voids to remain near the center of the cellulose. This allows for better compatibility with resins, facilitates the formation of internal voids, and makes it easier to form composites that are stronger and lighter.

[0028] 1.1.3. Particle Structure As described above, the derivatized cellulose particles have pores and internal voids. This makes it easier to maintain the internal voids when compounded with resin, as the resin does not penetrate them. This makes it easier to maintain a low apparent density of the particles.

[0029] Furthermore, cellulose particles have a higher apparent density at their edges than at their center. This makes it easier to maintain a low apparent density of the particles and to form lightweight composites.

[0030] 1.1.4. Apparent density of particles The apparent density of the cellulose particles constituting the filler in this embodiment is 1.0 g / cm³. 3 The following is true: The apparent density of cellulose particles is 0.9 g / cm³. 3 Preferably, it is 0.8 g / cm³. 3 The following is more preferable:

[0031] Here, "apparent density" refers to the density calculated using the volume occupied by the object itself and the volume of internal voids. In other words, apparent density is the density when the internal voids of an object are included in the object's volume, but the pores are not. Apparent density can be measured by methods such as the Le Chatelier gravity bottle method or the immersion method.

[0032] On the other hand, "true density" refers to the density calculated using only the volume occupied by the substance itself. In other words, true density is the density when pores and internal voids are not included in the volume. True density can be determined by methods such as the pycnometer method. The true density of cellulose is 1.5 g / cm³. 3 It is to that extent.

[0033] 1.2. Resin The filler of this embodiment is compounded with a resin. Such resins are not particularly limited, but include one or more mixtures selected from polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetate, polystyrene, polyisoprene, polymethacrylic acid, polycarbonate, cellulose acetate, acrylonitrile-butadiene-styrene copolymer, polyethylene, polypropylene, polyacetal, polyamide, fluororesin, polyether chloride, and polyester.

[0034] The resin into which the filler of this embodiment is compounded is preferably one or a mixture of two or more selected from polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetate, polystyrene, polyisoprene, polymethacrylic acid, polycarbonate, cellulose acetate, acrylonitrile-butadiene-styrene copolymer, polyethylene, polypropylene, and polyacetal.

[0035] The filler of this embodiment, when combined with these resins, more easily achieves compatibility with the resins and facilitates the formation of a composite that is stronger and lighter.

[0036] 1.2.1. Composite with resin The filler of this embodiment can be compounded with the resin described above to form a composite (resin composition). Known methods such as melt mixing and solution mixing can be used for compounding. Additives such as colorants, antioxidants, and UV absorbers may also be incorporated during compounding.

[0037] In this embodiment, the filler has derivatized cellulose particles near the surface, resulting in high compatibility with resins and improved flexibility near the surface. Therefore, composites can be easily formed by methods such as melt kneading.

[0038] 1.3. Effects and Mechanisms The filler of this embodiment allows for easy compounding with resins and enables the creation of lighter composites. Specifically, since the cellulose at least on the surface of the particles is hydrophobicized by derivatization, the compatibility with resins is improved, resulting in a composite that is less prone to interfacial delamination and has good strength when compounded with resins. Furthermore, the apparent density of the particles is 1.0 g / cm³. 3 Therefore, the true density of cellulose and cellulose derivatives is 1.5 g / cm³. 3 It is smaller than that. This allows for the construction of lightweight composites.

[0039] In this embodiment, the apparent density of the cellulose particles in the filler is relatively low on the inside and high on the outside (outer edge). Therefore, when mixed with resin, the denser outer shell suppresses the penetration of the resin, making it difficult for the internal voids to be filled with resin, thus enabling a reduction in the weight of the composite when compounded.

[0040] 2.Resin composition The resin composition according to this embodiment comprises the filler described above and the resin described above. The resin composition of this embodiment has excellent strength as a result of good dispersion of the cellulose particles of the filler described above, and a lightweight molded article can be obtained due to the structure and apparent density of the cellulose particles described above.

[0041] 3. Method for manufacturing fillers The method for producing the filler according to this embodiment is a method for producing the above-mentioned filler for compounding with a resin, and comprises a grinding step of grinding cellulose to obtain cellulose particles having pores, and a derivatization step of derivatizing the particles in a liquid to derivatize the cellulose located on the surface and outer edge of the particles.

[0042] 3.1. Grinding Process The method for grinding cellulose is not particularly limited and any known method can be used, such as a bead mill, ball mill, FM mixer, Henschel mixer, super mixer, turbo mill, roller mill, jet mill, hammer mill, or pin mill. Furthermore, the grinding process may be carried out while cooling.

[0043] It is more preferable to grind cellulose using a bead mill or a ball mill. Using a bead mill makes it easier to distribute pores more uniformly in the ground cellulose particles. An example of a bead mill device is the Drystar® SDA1 dry bead mill (manufactured by Ashizawa Finetech Co., Ltd.), and beads made of materials such as zirconia or SUS can be used.

[0044] 3.2. Derivatization process Derivatization of cellulose particles can be carried out, for example, by reacting cellulose particles with acid chloride in NMP. This reaction causes the cellulose molecules on the surface of the cellulose particles to be substituted (esterified) and become derivatives. Molecules with a high degree of substitution dissolve into the NMP, so the surface of the cellulose particles is always maintained coated with cellulose with a low degree of substitution. On the other hand, cellulose molecules with a high degree of substitution expand in volume, narrowing or blocking the pores of the cellulose particles. As a result, the outer edge of the cellulose particle is derivatized, while unreacted cellulose, pores, and internal voids remain inside.

[0045] To stop this derivatization reaction midway, the amount of esterifying agent added can be adjusted. The substituted functional groups become highly compatible with the aforementioned resin, and by mixing (compositing) the cellulose particle powder (the filler mentioned above) that has undergone this treatment with the resin, a composite with a strong interface between the resin and the cellulose particles can be obtained.

[0046] 3.3. Other processes The method for producing the filler in this embodiment may include steps other than the grinding step and the derivatization step, such as a washing step, a filtration step, a drying step, and a classification step.

[0047] According to the filler manufacturing method of this embodiment, cellulose can be derivatized from the surface of the cellulose particles toward the interior. This causes swelling in the area from the surface to the outer edge of the cellulose, which closes the pores near the surface, making it easier to retain pores and internal voids near the center of the cellulose particles. As a result, the apparent density of the cellulose particles can easily be increased to 1.0 g / cm³. 3 The following can be done:

[0048] 4. Experimental Examples The present invention will be described in detail below with reference to experimental examples, but the present invention is not limited to these experimental examples. Hereinafter, "parts" and "%" refer to mass unless otherwise specified. Unless otherwise specified, evaluations are performed under conditions of 25°C and 40.0% relative humidity.

[0049] 4.1. Preparation of fillers 4.1.1. Crushing Dissolved pulp was used as the raw material. The dissolved pulp was crushed using a bead mill (Drystar® SDA1 (manufactured by Ashizawa Finetech Co., Ltd.)). Zirconia beads (3 mm in diameter) were used. The bead filling rate was set to 70% (by volume), and the stirring conditions were: peripheral speed 2-7 m / s, cellulose input rate 0.2-1 kg / h. The humidity inside the apparatus was set to 80%. The reason for setting the humidity to 80% was to increase contact between particles and make it easier for pores to form.

[0050] Samples of filler powder were obtained after grinding for 30 minutes and 60 minutes. The pore diameter of the obtained filler was measured using a transmission electron microscope. Pores with a diameter of 100 nm or less were classified as "narrow," and those with a diameter exceeding 100 nm were classified as "wide," and the results are listed in Table 1. Untreated dissolved pulp was not considered to have pores, so its pore diameter was not measured.

[0051] 4.1.2. Derivatization The filler powder obtained above was esterified (derivativeized) as follows. After grinding the cellulose, esterification was performed in a heterogeneous solid-liquid system. Specifically, 6.0 g of cellulose powder (dry weight equivalent, 37 mmol / glucose units) was placed in a reactor and dispersed in 240 ml of pyridine under a nitrogen atmosphere, and activated by stirring overnight at room temperature. Then, the dispersion was cooled to approximately 10°C, and 3.18 g (10.8 mmol) of stearoyl chloride and 6.22 g (67.0 mmol) of propionyl chloride were pre-mixed and placed in the reactor. After stirring while heating at 90°C for 4 hours, 23 g of 13% sodium hydroxide aqueous solution was slowly added dropwise, and the mixture was stirred for 1 hour while cooling to 40°C. Further, 260 ml of water was added to precipitate the product, which was recovered by suction filtration. The obtained solid was washed twice with 200 ml of water, and then washed with 200 ml of methanol until the color of the filtrate disappeared (3-4 times). The washed solids were vacuum-dried at 105°C for 5 hours to obtain 10.0 g of powdered cellulose filler (cellulose propionate stearate) (yield 98%).

[0052] In the above derivatization treatment, the amount of esterifying agent used was (10.8 + 67.0) / 37 = 2.1. Fillers for each experimental example were prepared by changing the amount of esterifying agent used as shown in Table 1.

[0053] 4.2. Evaluation of Fillers As described above, experiments were conducted by varying the grinding state and the amount of esterifying agent added, and the apparent density was measured using the Le Chatelier specific gravity bottle method according to JIS Z 8807:2012. The measured values ​​of the apparent density are shown in Table 1.

[0054] We evaluated its dispersibility in acetone. Acetone and each filler (0.1% by mass) were sealed in a sample cell of the LUMiSizer dispersion stability analyzer (manufactured by LUM Corporation), and dispersed by ultrasonic treatment at 50W for 60 seconds using an ultrasonic homogenizer UX-050 manufactured by Mitsui Electric Seiki Co., Ltd., followed by standing for 10 seconds.

[0055] Subsequently, the device was activated, and the cell transmittance (absorbance) of the laser light was measured after 5 minutes under a centrifugal acceleration of 10G. The measurement positions were set at 1 / 4 and 3 / 4 of the cell's total length from the end of the cell.

[0056] Since the ratio of absorbances is equal to the ratio of concentrations, A 1 / 4 / A 3 / 4 =C 1 / 4 / C 3 / 4 Here A 1 / 4 A is the absorbance at a position 1 / 4 of the way from the edge of the cell to the end of the cell's total length. 3 / 4 This is the absorbance at a position 3 / 4 of the way from the edge of the cell to the end of the cell's total length, C 1 / 4 This is the concentration at a position 1 / 4 of the way from the edge of the cell to the end of the cell's total length, C 3 / 4 This represents the concentration at a position 3 / 4 of the way from the edge of the cell to the end of the cell's total length.

[0057] As an evaluation of acetone dispersibility, C 1 / 4 / C 3 / 4 If the value was in the range of 0.1 or greater and 10 or less, it was evaluated as "A"; if it was less than 0.1 and greater than 10, and between 0.01 and 100, it was evaluated as "B"; and if it was in any other range, it was evaluated as "C". The results for each experimental example are recorded in Table 1.

[0058] 4.3. Evaluation Results The following findings were obtained from the above experimental examples. • Because the raw material before grinding (untreated) has no pores, its apparent density did not change even after esterification. When material is ground using a bead mill, it forms aggregates of minute particles with pores. When this is esterified, the apparent density changes and decreases. This is thought to be because esterification causes volume expansion, closing some of the pores on the particle surface and creating internal voids. As an alternative evaluation method for compatibility with resins, we evaluated the dispersibility in acetone and found that good dispersibility of the filler in acetone can be achieved by reacting with an esterifying agent amount of 0.9 or more relative to the equivalent amount. If a resin has good dispersibility in acetone, it is likely to have good dispersibility in resins with low acetone resistance, i.e., resins with good affinity for acetone. Examples of resins with low acetone resistance (high affinity for acetone) include the aforementioned polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetate, polystyrene, polyisoprene, polymethacrylic acid, polycarbonate, cellulose acetate, acrylonitrile-butadiene-styrene copolymer, polyethylene, polypropylene, and polyacetal.

[0059] The present invention includes configurations substantially identical to those described in the embodiments, for example, configurations with the same function, method, and results, or configurations with the same purpose and effect. Furthermore, the present invention includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. Furthermore, the present invention includes configurations that produce the same effects or achieve the same purpose as those described in the embodiments. Finally, the present invention includes configurations that add known technology to the configurations described in the embodiments.

[0060] The following can be derived from the embodiments and modifications described above.

[0061] Fillers are, A filler for compounding with resin, It consists of particles that mainly contain cellulose, The cellulose located on the surface of the aforementioned particles is derivatized, The apparent density of the aforementioned particles is 1.0 g / cm³. 3 The following applies:

[0062] This filler facilitates compounding with resins and allows for the creation of lighter composites. Specifically, because the cellulose on at least the surface of the particles is hydrophobicized through derivatization, the compatibility with resins is improved, resulting in a composite with good strength that is less prone to interfacial delamination when compounded with resins. Furthermore, the apparent density of the particles is 1.0 g / cm³. 3 Therefore, the true density of cellulose and cellulose derivatives is 1.5 g / cm³. 3 It is smaller than that. This allows for the construction of lightweight composites.

[0063] In the above filler, The aforementioned particles may have internal voids.

[0064] This filler has internal voids in its particles, so when compounded with resin, the resin does not penetrate these voids, making it easier to maintain the voids. This makes it easier to keep the apparent density of the particles low.

[0065] In the above filler, The particles may have a higher apparent density at the outer edges than at the center.

[0066] This filler makes it easier to maintain a low apparent particle density and form lightweight composites.

[0067] In the above filler, The cellulose located on the surface of the particle may have a higher degree of substitution by derivatization than the cellulose located on the outer edge of the particle.

[0068] This filler offers better compatibility with the resin and facilitates the formation of internal voids. This makes it easier to create a composite that is stronger and lighter.

[0069] In the above filler, The resin may be one or a mixture of two or more selected from polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetate, polystyrene, polyisoprene, polymethacrylic acid, polycarbonate, cellulose acetate, acrylonitrile-butadiene-styrene copolymer, polyethylene, polypropylene, and polyacetal.

[0070] This filler makes it easier to achieve compatibility with resins and to form composites that are stronger and lighter.

[0071] The resin composition is The material comprises any of the above-mentioned fillers and the resin.

[0072] This resin composition makes it possible to obtain molded articles that are lightweight and have excellent strength.

[0073] The method for manufacturing the filler is, A grinding step in which cellulose is crushed to obtain cellulose particles having pores, A derivatization step involves derivatizing the particles in a liquid to derivatize the cellulose located on the surface and outer edge of the particles, It holds.

[0074] This filler manufacturing method allows for the derivatization of cellulose particles from the surface inward. This causes swelling from the surface to the outer edge of the cellulose, which closes the pores near the surface, making it easier to retain pores and internal voids near the center of the cellulose particle. As a result, the apparent density of the cellulose particles can easily reach 1.0 g / cm³. 3 The following can be done:

Claims

1. A filler for compounding with resin, It consists of particles that mainly contain cellulose, The cellulose located on the surface of the aforementioned particles is derivatized, The apparent density of the aforementioned particles is 1.0 g / cm³. ３ The following are fillers.

2. In claim 1, The aforementioned particles are fillers having internal voids.

3. In claim 1, The aforementioned particles are fillers in which the apparent density is higher at the outer edges than at the center.

4. In claim 1, The cellulose located on the surface of the particle is a filler with a higher degree of substitution by derivatization than the cellulose located on the outer edge of the particle.

5. In claim 1, The resin is a filler, which is one or more selected from polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetate, polystyrene, polyisoprene, polymethacrylic acid, polycarbonate, cellulose acetate, acrylonitrile-butadiene-styrene copolymer, polyethylene, polypropylene, and polyacetal.

6. A resin composition comprising the filler according to claims 1 to 5 and the resin.

7. A process of crushing cellulose to obtain cellulose particles having pores, The particles are derivatized in a liquid, the cellulose located on the surface and outer edge of the particles is derivatized, and the apparent density of the particles is 1.0 g / cm³. ３ The following steps, A method for manufacturing a filler for compounding with a resin.

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