ПОРОШОК ТАЛЬКА, СРЕДСТВО ДЛЯ УЛУЧШЕНИЯ СВОЙСТВ СМОЛЫ И КОМПОЗИЦИЯ СМОЛЫ

Abstract

Provided is a talc powder having a B / A value of 0.10 or less wherein A (m2 / g) represents a BET specific surface area of the talc powder and B (% by mass) represents a weight loss determined by a thermogravimetry-differential thermal analysis at 200 to 700°C.

Description

Talc powder, resin property improver, resin composition

[0001] The present invention relates to a talc powder, a resin property improver, and a resin composition.

[0002] When producing resin molded products, various fillers are blended with the resin raw materials to improve physical properties such as mechanical strength. One such filler is talc. Talc is the softest of all rock-forming minerals, has cleavage properties that make it easy to peel, has a smooth feel, and is chemically stable, making it widely used in combination with various raw materials.

[0003] Due to its excellent versatility, talc is used in a wide range of fields, such as plastics (resins), papermaking, cosmetics, medicines, fertilizers, paints, ceramics, etc. For example, resin compositions containing talc are widely used in various fields, such as automobile parts, home appliance parts, and office equipment parts.

[0004] On the other hand, with the advancement of technology in various fields, there is a growing trend to achieve high levels of physical properties at the material design stage, and various improvements have been made to the widely used talc in order to bring out its inherent effective physical properties.

[0005] For example, Patent Document 1 describes a granular talc obtained by degassing and then compressing powdered talc having an average primary particle size of 0.1 to 10 μm without directly compressing it, and having a bulk density of 0.6 to 0.94 g / cm ３ and a destruction rate of 70 to 100% by weight has been proposed.

[0006] Japanese Patent Application Laid-Open No. 2005-104794

[0007] However, Patent Document 1 examines whether or not the dispersibility is excellent when the compound is added to a thermoplastic resin and melt-mixed, but does not examine whether or not the physical properties of the resin (e.g., physical properties such as flexural modulus) can be improved. In other words, it cannot be said that the compound aims to achieve a high level of physical properties at the material design stage.

[0008] In view of the above, an object of the present invention is to provide a talc powder that, when added to a resin composition, can improve the physical properties of the resulting resin compared to when conventional talc powders are added.

[0009] As a result of intensive research aimed at solving the above problems, the present inventors have found that the problems can be solved by the present invention described below.

[0010] [1] BET specific surface area is A (m ２ [2] A talc powder having a BET specific surface area of ​​3 to 20 m, wherein B / A is 0.10 or less, where B is the weight loss rate measured by thermogravimetric differential thermal analysis at 200 to 700°C (mass%) and A is the weight loss rate measured by thermogravimetric differential thermal analysis at 200 to 700°C (mass%). ２ [3] The talc powder according to [1], wherein the bulk density is 0.05 to 0.35 g / cm. ３ [4] The talc powder according to any one of [1] to [3], which has a median diameter (D50) of 1 to 10 μm. [5] A resin property improver comprising the talc powder according to any one of [1] to [4]. [6] A resin composition comprising the talc powder according to any one of [1] to [4] and a resin. [7] A resin composition comprising the resin property improver according to [5] and a resin.

[0011] According to the present invention, it is possible to provide a talc powder that, when added to a resin composition, can improve the physical properties of the resin compared to when conventional talc powders are added.

[0012] [Talc Powder] The talc powder according to one embodiment of the present invention (this embodiment) has a BET specific surface area of ​​A (m ２ / g), and the weight loss rate by thermogravimetric differential thermal analysis at 200 to 700°C is B (mass%), and B / A is 0.10 or less.

[0013] A B / A ratio of 0.10 or less indicates that the amount of moisture present on conventional talc powder is very low. In other words, it can be inferred that the surface of the talc powder is in a highly hydrophobic state, which increases its affinity with resins and is thought to improve the physical properties of the resins (especially the elastic modulus). B / A is preferably 0.02 to 0.09, and more preferably 0.025 to 0.085.

[0014] The weight loss rate B by thermogravimetric differential thermal analysis can be measured and determined, for example, by the following method using a known device. 7 mg of a talc powder sample is placed in a differential thermobalance (for example, ThermoPlus2, manufactured by Rigaku Corporation) and heated (room temperature to 950°C), and the weight loss rate (mass%) is determined from 200°C to 700°C. The temperature rise rate is 10°C / min. The measurement atmosphere is preferably a nitrogen atmosphere.

[0015] From the viewpoint of exerting the effect due to hydrophobicity, the weight loss rate B (mass%) is preferably 1.2 mass% or less, more preferably 1 mass% or less, and even more preferably 0.7 mass% or less. The lower limit is not particularly limited, but in practice it is about 0.05 mass%.

[0016] To make the B / A ratio according to this embodiment 0.10 or less, it is preferable to pulverize the raw material talc under conditions of higher temperature and higher shear force than those used under the pulverization conditions of a normal jet mill. Specifically, it is preferable to produce the powder by adjusting the temperature, pressure, etc. using a pulverization means capable of instantaneously applying high shear force at a high temperature using superheated steam (saturated steam and steam obtained by further heating saturated steam) as fluid energy, such as a steam jet mill described below.

[0017] In this embodiment, the bulk density (solidification) of the talc powder is 0.05 to 0.35 g / cm ３ is preferably 0.10 to 0.30 g / cm ３ More preferably, it is 0.13 to 0.28 g / cm ３ It is more preferable that the density is 0.05 to 0.35 g / cm ３This makes it easier to obtain a higher elastic modulus when mixed with a resin.

[0018] The above-mentioned bulk density indicates that the talc powder of this embodiment is in a very bulky state. Usually, the particle size and aspect ratio of the talc powder are optimized, with the bulk density being increased in consideration of handling, such as transportation. In contrast, this embodiment focuses on a "low bulk density state (= very bulky state)," which is likely to be excluded from consideration based on common technical knowledge, and the present invention was arrived at through an idea unconstrained by common technical knowledge.

[0019] Here, the bulk density can be determined by the packed bulk density measured using a powder property evaluation device (Powder Tester PT-X manufactured by Hosokawa Micron Corporation). The measurement conditions are as follows: a sample is fed onto a sieve with an opening of 710 μm, and the sample is sieved at a speed of 100 cm with an amplitude of 1.5 mm. ３ The sample is added so that the powder surface position of the cap placed on the bulk density measurement cup is constant, and tapping is performed 180 times.

[0020] Furthermore, from the viewpoint of obtaining a high elastic modulus when mixed with a resin, the median diameter (volume basis, D50) of the talc powder according to this embodiment is preferably 1 to 10 μm, more preferably 1.5 to 9.5 μm, and even more preferably 1.7 to 8.5 μm. Furthermore, D50 is preferably 2.3 to 8 μm, and more preferably 2.3 to 7 μm.

[0021] Here, the median diameter can be determined as a volume-based median diameter (D50: particle diameter at 50% of the cumulative volume from the small particle diameter side) by measuring the particle size distribution using a laser diffraction particle size distribution analyzer (SALD-200V ER manufactured by Shimadzu Corporation).

[0022] The specific surface area (BET specific surface area) of the talc powder of this embodiment is 3 to 20 m ２ / g, and 3 to 18 m ２ / g, and 6.0 to 16.0 m ２ / g, and more preferably 6.5 to 15.0 m ２ / g, and more preferably 6.5 to 14.0 m２ / g. It is even more preferable that the specific surface area is 3 to 20 m ２ / g, a high elastic modulus can be obtained when mixed with a resin. Here, the specific surface area can be determined by measuring using a specific surface area / pore distribution measuring device (BELSORP MINI II manufactured by Microtrac-Bell Co., Ltd.). For sample preparation, it is preferable to dry the sample at 100°C for 90 minutes using a vacuum dryer.

[0023] The talc powder according to this embodiment is preferably natural talc (non-synthetic talc) rather than synthetic talc. Synthetic talc is talc produced by chemical synthesis, for example, by hydrothermal synthesis, in which raw materials containing magnesium and silicon are heated at high temperatures under pressure. On the other hand, natural talc is a naturally occurring mineral. Natural talc may contain calcium carbonate, dolomite, and the like as trace components. These trace components improve impact resistance when added to resins. Therefore, natural talc powder is preferred as the talc powder according to this embodiment.

[0024] [Method for Producing Talc Powder] The method for producing talc powder according to this embodiment includes a pulverization step in which raw talc is pulverized using a steam jet mill. As described above, pulverization using a steam jet mill uses superheated steam as the fluid energy for pulverization, and therefore high shear force can be applied instantaneously. Therefore, compared to a jet mill under typical conditions that uses compressed air as the fluid energy, a larger shear force acts instantaneously on the raw talc powder, which efficiently removes moisture from the surface and exhibits good hydrophobicity. Therefore, when mixed with a resin to form a resin composition, it is believed that the inherent property-improving effect of the talc powder is more easily exhibited at a high level.

[0025] In the pulverization treatment using a steam jet mill, for example, the temperature of the superheated steam (temperature before entering the pulverization area) for steam jet mill pulverization is preferably 300 to 500°C, and the pressure of the superheated steam (pulverization pressure) is preferably 3.5 to 15.0 MPa in gauge pressure. By appropriately adjusting within the above ranges, the aforementioned B / A, bulk density, specific surface area, average particle size (D50), etc. can be set within the desired ranges. Note that superheated steam can be generated at the desired temperature using a commercially available boiler, superheater (steam superheater), etc.

[0026] In addition, the median diameter D of the raw material talc ０ is preferably 11 to 20 μm, and the bulk density is 0.5 to 2 g / cm ３ When the amount is within these ranges, good grinding efficiency can be obtained, and the talc powder according to the present embodiment can be more easily obtained.

[0027] The talc powder (pulverized talc powder) obtained as described above can be subjected to classification or other treatments as necessary and used in a variety of applications.

[0028] [Resin Property Improver] The resin property improver according to this embodiment includes the talc powder according to this embodiment. By mixing the resin property improver with a resin (for example, a thermoplastic resin described below), the resin properties (particularly the elastic modulus) can be improved. In other words, the resin property improver is suitable as a resin property improver to be added to a resin (including a resin composition).

[0029] In order to fully exert its effects, the content of the talc powder according to this embodiment in the resin property improver is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 100% by mass.

[0030] The resin property improver may contain, for example, a surface treatment agent such as a silane coupling agent or an acid-modified polymer (for example, maleic acid-modified PP).

[0031] [Resin Composition] The resin composition according to this embodiment contains the talc powder according to this embodiment (or the resin property improver according to this embodiment) and a resin. Examples of the resin include a thermoplastic resin (including a thermoplastic elastomer for convenience), a thermosetting resin, a rubber, and a cellulose-based resin.

[0032] Examples of the thermoplastic resin include olefin-based resins such as polypropylene, polyethylene, 4-methylpentene-1 resin, polybutene-1 resin, ethylene-propylene random copolymer, ethylene-propylene block copolymer, propylene-1-butene copolymer, propylene-ethylene-butene-1 copolymer, propylene-4-methylpentene copolymer, ethylene-butene-1 copolymer, ethylene-hexene copolymer, ethylene-heptene copolymer, ethylene-octene copolymer, ethylene-4-methylpentene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, ethylene-methacrylic acid copolymer, and ethylene-methacrylic acid ester copolymer; styrene-based resins such as styrene homopolymer, acrylonitrile-styrene copolymer (AS resin), and acrylonitrile-butadiene-styrene copolymer (ABS resin); polyvinyl chloride, polyvinylidene chloride; polytetrafluoroethylene, ... Examples of the resin include fluororesins such as fluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, ethylene-tetrafluoroethylene copolymer, polychlorotrifluoroethylene resin, and polyvinylidene fluoride; polyvinyl alcohol; polyamide resins such as nylon 6, nylon 6,6, nylon 6,10, nylon 11, nylon 12, nylon 6,12, polyhexamethylenediamine terephthalamide, polyhexamethylenediamine isophthalamide, and xylene group-containing polyamide; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; acrylic resins such as polymethyl acrylate and polymethyl methacrylate; polyoxymethylene resins such as polyoxymethylene homopolymer and polyoxymethylene copolymer; polycarbonate; polyacetal; polyphenylene ether; polyethersulfone; polyetherketone; and liquid polyester.

[0033] Examples of the thermoplastic elastomer include polyolefin-based thermoplastic elastomers, polystyrene-based thermoplastic elastomers, polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, low-crystalline 1,2-polybutadiene-based thermoplastic elastomers, fluorine-based thermoplastic elastomers, chlorinated polymer-based thermoplastic elastomers, and ion-crosslinked thermoplastic elastomers.

[0034] Examples of the thermosetting resin include phenolic resins, urea resins, melamine resins, alkyd resins, thermosetting acrylic resins, unsaturated polyester resins, diallyl phthalate resins, epoxy resins, thermosetting silicone resins, thermosetting polyimides, thermosetting resins derived from cyclopentadiene, thermosetting resins derived from aromatic nitriles; furan resins, ketone resins, xylene resins, and thermosetting resins containing condensed polycyclic aromatics.

[0035] Examples of the rubber include natural rubber, styrene butadiene rubber, butadiene rubber, chloroprene rubber, isoprene rubber, isobutylene-isoprene rubber, butyl rubber, ethylene propylene rubber, acrylonitrile butadiene rubber, nitrile rubber, silicone rubber, fluororubber, acrylic rubber, and epichlorohydrin rubber.

[0036] Examples of the cellulose-based resin include acetyl cellulose, acetyl propionyl cellulose, acetyl butyl cellulose, ethyl cellulose, and nitrocellulose.

[0037] The content of the talc powder according to one embodiment of the present invention is preferably 0.5 to 60 parts by mass, more preferably 1 to 35 parts by mass, per 100 parts by mass of the resin in the resin composition.

[0038] The resin composition according to one embodiment of the present invention may contain one or more of antioxidants, heat stabilizers, weather resistance improvers, release agents, lubricants, pigments, dyes, plasticizers, antistatic agents, flame retardants, etc., as needed. Furthermore, fillers other than the talc powder according to one embodiment of the present invention may be contained as needed. Examples of such fillers include calcium carbonate, clay, synthetic silicon, titanium oxide, carbon black, barium sulfate, mica, glass fiber, whiskers, carbon fiber, magnesium carbonate, kaolin, graphite, molybdenum disulfide, and zinc oxide. Furthermore, depending on the application, a solvent or dispersion medium may be added to form a liquid resin composition.

[0039] The talc powder can be blended and kneaded into the resin by known methods. For example, a commonly used single-screw kneading extruder or twin-screw kneading extruder can be used to blend and knead the talc powder into polypropylene. The resin composition according to this embodiment can be used for various applications, such as automotive interior and exterior parts, home appliance parts, and office equipment parts.

[0040] Next, the present invention will be specifically explained with reference to examples, but the present invention is not limited to these examples.

[0041] [Talc powder] Median diameter (D50) 12.7 μm, bulk density 0.72 g / cm ３ The raw material talc (talc produced in Pakistan was coarsely pulverized using a roller mill to give the above-mentioned D50) was pulverized to each median diameter shown in Table 1 using a steam jet mill (hereinafter sometimes referred to as "s-JET") and a jet mill.

[0042] (1) Conditions for pulverization using a steam jet mill The equipment used was a steam jet mill s-JET150 manufactured by Netzsch Trockenmahltechnik. Superheated steam temperature (temperature before entering the pulverization area): 360°C. Pulverization pressure (gauge pressure): 3.8 MPa. Particle size adjustment was performed by adjusting the rotation speed of a classifier attached to the steam jet mill.

[0043] (2) Pulverization Conditions Using a Jet Mill The equipment used was a counter jet mill AFG710 / 4 manufactured by Hosokawa Micron Corporation. Particle size adjustment was performed by adjusting the rotation speed of a classifier attached to the jet mill. Note that when D50 was 2.2 μm (Comparative Example 1), the particle size was adjusted by classification after pulverization.

[0044] With s-JET, bulky pulverized talc powder was obtained. On the other hand, with the jet mill, when viewed at the same D50 as with s-JET, a low-bulk pulverized talc powder was obtained. This is thought to be because, with a jet mill under normal conditions, the pulverization residence time is long, so that not only shear forces but also isotropic forces act on the talc, causing further pulverization rather than just surface peeling.

[0045] (Resin Composition) Resin compositions prepared using the talc powder prepared as described above were evaluated as follows.

[0046] Evaluation: Flexural Modulus The flexural modulus was measured in accordance with JIS K7171. The results are shown in Table 2. The resin composition was injection molded using an injection mold (JIS K7171 Type B1), and the flexural modulus of the resulting molded article (10 mm (width) × 4 mm (thickness) × 80 mm (length)) was evaluated using an Autograph AG-Xplus (temperature: 23°C, bending speed: 2 mm / min) in accordance with JIS K7171. The resin of the resin composition constituting the molded article was polypropylene resin (PX-600N, manufactured by SunAllomer Co., Ltd.), and the amount of talc powder was 20 parts by mass per 100 parts by mass of the polypropylene resin.

[0047]

[0048] From Table 1, it can be seen that Examples 1 to 3, in which B / A is 0.10 or less, were able to improve the resin physical properties more than Comparative Examples 1 to 3. In other words, it can be said that the resin is suitable as a resin property improver for addition to a resin or resin composition.