Molding material

Abstract

To provide a molding material that can be suitably used for producing a molded body exhibiting superior mechanical strength and humidity resistance.SOLUTION: A molding material of the present invention comprises a phenolic resin and a filler, wherein the phenolic resin comprises an alkylbenzene-modified novolac-type phenolic resin, and a ratio of the alkylbenzene-modified novolac-type phenolic resin to the total phenolic resin is 71.0 mass% or more and 99.0 mass% or less. It is preferable that the alkylbenzene-modified novolac-type phenolic resin includes a xylene-modified novolac-type phenolic resin.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a molding material. [Background technology]

[0002] For example, molded articles such as mechanical parts used in automobiles and the like are required to have heat resistance and mechanical strength. To satisfy these properties, ceramics and metals have conventionally been used as materials for forming such molded articles. However, molded articles made of ceramics or metals have various problems, such as large individual weight, time-consuming processing, and high costs. As a means for solving these problems, molded articles made of plastic materials have attracted attention from the viewpoint of reducing the weight of parts.

[0003] As a material (molding material) used to form a molded body, phenolic resin molding materials containing phenolic resins have been attracting attention among plastic materials from the viewpoints of heat resistance and mechanical strength. Molded bodies made from phenolic resin molding materials are superior to ceramic or metal molded bodies in that they have a small individual weight, are easy to process, and have high heat resistance. In addition, glass fiber, silica, etc. are used as fillers to impart heat resistance and mechanical strength to the molded body.

[0004] However, molded articles manufactured using phenolic resin molding materials tend to absorb moisture and swell during storage or use. Therefore, when the molded articles manufactured using phenolic resin molding materials are precision parts, they are prone to malfunction and have low reliability. For these reasons, there is a demand for improved moisture resistance, or in other words, improved dimensional stability under high humidity conditions.

[0005] Patent Documents 1 to 3 describe techniques for improving the mechanical strength and moisture resistance of mechanical parts molded using phenolic resin molding materials.

[0006] Patent Document 1 discloses a technique for improving wear characteristics by blending graphite, which is a solid lubricant, into a phenolic resin molding material.

[0007] Patent Document 2 discloses a technique for improving mechanical properties by using glass fiber in addition to graphite. In the technique described in Patent Document 2, the graphite and glass fiber contents in the entire molding material are 5% by weight or more and 20% by weight or less, and 40% by weight or more and 60% by weight or less.

[0008] Patent Document 3 discloses a technique for improving dimensional accuracy, heat resistance, and humidity-resistant dimensional stability by blending an alkylbenzene-modified novolac phenolic resin with glass fibers. In the technique described in Patent Document 3, the total content of (A) novolac phenolic resin including alkylbenzene-modified novolac phenolic resin, (B) resol phenolic resin, and (C) hexamethylenetetramine is 15% by weight or more and 30% by weight or less, and the content of glass fibers is 10% by weight or more and 20% by weight or less, based on the entire molding material.

[0009] However, even with these techniques, it has not been possible to obtain a molding material that can provide a molded article having both sufficiently high levels of mechanical strength and moisture resistance, and there is still room for further improvement. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-47971 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-265033 [Patent Document 3] Japanese Patent Application Laid-Open No. 2011-68705 Summary of the Invention [Problem to be solved by the invention]

[0011] An object of the present invention is to provide a molding material that can be suitably used to produce molded articles that are excellent in mechanical strength and moisture resistance. [Means for solving the problem]

[0012] These objects can be achieved by the present invention as set forth in (1) to (5) below. (1) A molding material containing a phenolic resin and a filler, the phenolic resin includes an alkylbenzene-modified novolac phenolic resin, A molding material characterized in that the ratio of the alkylbenzene-modified novolac phenolic resin to the total amount of the phenolic resin is 71.0% by mass or more and 99.0% by mass or less.

[0013] (2) The molding material according to (1) above, wherein the alkylbenzene-modified novolac phenolic resin contains a xylene-modified novolac phenolic resin.

[0014] (3) The molding material according to (1) or (2) above, wherein the content of the phenolic resin is 10.0% by mass or more and 35.0% by mass or less.

[0015] (4) The molding material according to any one of (1) to (3) above, further containing hexamine.

[0016] (5) The molding material according to (4) above, wherein the content of the hexamine is 0.5% by mass or more and 3.0% by mass or less. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide a molding material that can be suitably used to produce a molded article that is excellent in mechanical strength and moisture resistance. DETAILED DESCRIPTION OF THE INVENTION

[0018] Preferred embodiments of the present invention will be described in detail below. [1] Molding material First, the molding material of the present invention will be described.

[0019] The molding material of the present invention is a molding material containing a phenolic resin and a filler, characterized in that the phenolic resin contains an alkylbenzene-modified novolac-type phenolic resin, and the ratio of the alkylbenzene-modified novolac-type phenolic resin to the total phenolic resin is 71.0 mass% or more and 99.0 mass% or less.

[0020] By satisfying these conditions, it is possible to provide a molding material that can be suitably used to produce molded articles that are excellent in mechanical strength and moisture resistance.

[0021] More specifically, when the molding material contains an alkylbenzene-modified novolac phenolic resin and the ratio of the alkylbenzene-modified novolac phenolic resin to the total phenolic resin is within a predetermined range, the resulting molding material can have both excellent mechanical strength and moisture resistance.

[0022] Here, the alkylbenzene-modified novolac phenolic resin refers to a novolac phenolic resin in which an alkylbenzene such as xylene or toluene is bonded to the novolac phenolic resin via a covalent bond such as a methylene bond.

[0023] By blending this alkylbenzene-modified novolac phenolic resin into a molding material, it is possible to improve the moisture resistance of the molding material while maintaining a practical level of mechanical strength compared to blending an unmodified novolac phenolic resin. This effect is believed to be achieved by substituting the hydrophilic hydroxyl groups of the phenolic resin with the hydrophobic alkylbenzene, thereby reducing the water absorption of the molding material.

[0024] On the other hand, if the above conditions are not met, the above excellent effects cannot be obtained.

[0025] For example, if the ratio of the alkylbenzene-modified novolac phenolic resin to the total phenolic resin is less than the lower limit, the moisture resistance of the molded article produced using the molding material cannot be sufficiently excellent. On the other hand, if the ratio of the alkylbenzene-modified novolac phenolic resin to the total phenolic resin exceeds the upper limit, the moisture resistance is improved, but the mechanical strength of the molded article produced using the molding material cannot be sufficiently excellent.

[0026] As described above, the proportion of the alkylbenzene-modified novolac phenolic resin relative to the total phenolic resin may be 71.0% by mass or more and 99.0% by mass or less, preferably 75.0% by mass or more and 95.0% by mass or less, and more preferably 80.0% by mass or more and 90.0% by mass or less. This makes it possible to make the above-mentioned effects of the present invention more pronounced.

[0027] [1-1] Phenolic resin The molding material of the present invention contains a phenolic resin. In the molding material of the present invention, the phenolic resin includes an alkylbenzene-modified novolac-type phenolic resin.

[0028] [1-1-1] Alkylbenzene modified novolac phenolic resin The molding material of the present invention contains an alkylbenzene-modified novolac phenolic resin as the phenolic resin.

[0029] The alkylbenzene-modified novolac phenolic resin may be obtained by any method, but can be produced, for example, by the method described below.

[0030] That is, first, alkylbenzene and formaldehyde are reacted in the presence of an acid catalyst to produce an alkylbenzene resin.

[0031] Next, the resulting alkylbenzene resin is reacted with a phenol, or a phenol and an aldehyde, in the presence of an acid catalyst to obtain an alkylbenzene-modified novolac phenolic resin.

[0032] In the alkylbenzene-modified novolac phenolic resin, the modification rate of alkylbenzene is preferably 3.0 mass% or more and 70.0 mass% or less, and more preferably 5.0 mass% or more and 50.0 mass% or less, based on the total of the phenolic resin and the alkyl-modified novolac resin.

[0033] This makes it possible to further improve the moisture resistance of a molded article produced using the molding material, and also to achieve a more favorable balance with the mechanical strength.

[0034] Examples of phenols used in producing alkylbenzene-modified novolac phenolic resins include phenol, o-cresol, m-cresol, p-cresol, xylenol, alkylphenols, catechol, and resorcinol. One or more selected from these may be used in combination.

[0035] In addition, examples of aldehydes used in producing alkylbenzene-modified novolac phenolic resins include aldehydes such as formaldehyde, paraformaldehyde, and benzaldehyde, as well as substances that are sources of these aldehydes, and one or more selected from these may be used in combination.

[0036] Examples of alkylbenzene-modified novolac phenolic resins include xylene-modified novolac phenolic resins and toluene-modified novolac phenolic resins, and among these, those containing xylene-modified novolac phenolic resins are preferred. This makes it possible to make the above-mentioned effects of the present invention more pronounced.

[0037] The content of alkylbenzene-modified novolac phenolic resin in the molding material of the present invention is preferably 5.0 mass% or more and 20.0 mass% or less, more preferably 7.5 mass% or more and 17.5 mass% or less, and even more preferably 10.0 mass% or more and 15.0 mass% or less. This makes it possible to make the above-mentioned effects of the present invention more pronounced.

[0038] [1-1-2] Phenolic resins other than alkylbenzene-modified novolac phenolic resins The molding material of the present invention contains, as the phenolic resin, not only the alkylbenzene-modified novolac phenolic resin but also a phenolic resin other than the alkylbenzene-modified novolac phenolic resin.

[0039] Examples of phenolic resins other than alkylbenzene-modified novolac-type phenolic resins include novolac-type phenolic resins other than alkylbenzene-modified novolac-type phenolic resins, resol-type phenolic resins, and the like.

[0040] By including a novolac phenolic resin other than an alkylbenzene-modified novolac phenolic resin as the phenolic resin, the production cost of the molding material can be reduced, and the mechanical strength of a molded article produced using the molding material can be further improved.

[0041] Furthermore, when the phenolic resin contains a resol type phenolic resin, the toughness of a molded body produced using the molding material can be improved, and the mechanical strength can be made even better.

[0042] As the novolac phenolic resin other than the alkylbenzene-modified novolac phenolic resin, for example, a resin obtained by reacting a phenol with an aldehyde in the presence of an acid catalyst at a molar ratio of the aldehyde to the phenol (aldehyde / phenol) of 0.7 or more and 0.9 or less can be used.

[0043] Furthermore, phenols used in producing novolac phenolic resins other than alkylbenzene-modified novolac phenolic resins are not particularly limited, but examples thereof include phenol, o-cresol, m-cresol, p-cresol, xylenol, alkylphenols, catechol, resorcinol, etc. These phenols may be used alone or in combination of two or more.

[0044] The aldehydes used in producing novolac phenolic resins other than alkylbenzene-modified novolac phenolic resins are not particularly limited, but examples thereof include aldehydes such as formaldehyde, paraformaldehyde, and benzaldehyde, as well as substances that generate these aldehydes, and solutions of these aldehydes. These aldehydes can be used alone or in combination of two or more.

[0045] When the phenolic resin contains a novolac type phenolic resin other than an alkylbenzene-modified novolac type phenolic resin, the ratio of the novolac type phenolic resin other than an alkylbenzene-modified novolac type phenolic resin to the total phenolic resin is preferably 0.1 mass% or more and 20.0 mass% or less, more preferably 0.5 mass% or more and 10.0 mass% or less, and even more preferably 1.0 mass% or more and 3.0 mass% or less.

[0046] As a resol-type phenolic resin, for example, one obtained by reacting phenols and aldehydes in the presence of a basic catalyst at a molar ratio of aldehydes to phenols (aldehydes / phenols) of 1.3 or more and 1.7 or less can be used.

[0047] Examples of phenols used in producing resol-type phenolic resins include phenol, o-cresol, m-cresol, p-cresol, xylenol, alkylphenols, catechol, and resorcinol, and one or more selected from these can be used in combination.

[0048] Aldehydes used in producing resol-type phenolic resins include, for example, aldehydes such as formaldehyde, paraformaldehyde, and benzaldehyde, as well as substances that are sources of these aldehydes, and one or more selected from these can be used in combination.

[0049] When the phenolic resin contains a resol-type phenolic resin, the ratio of the resol-type phenolic resin to the total phenolic resin is preferably 5.0 mass% or more and 40.0 mass% or less, more preferably 7.0 mass% or more and 30.0 mass% or less, and even more preferably 10.0 mass% or more and 20.0 mass% or less.

[0050] The content of the phenol resin in the molding material is preferably 10.0% by mass or more and 35.0% by mass or less, more preferably 12.0% by mass or more and 33.0% by mass or less, and even more preferably 15.0% by mass or more and 30.0% by mass or less. This makes it possible to make the above-mentioned effects of the present invention more pronounced.

[0051] [1-2] Filler The molding material of the present invention contains a filler.

[0052] As the filler, an appropriate one can be selected depending on the use and properties of the molded article to be produced.

[0053] The filler may be an inorganic filler or an organic filler, but is preferably an inorganic filler. This allows the molded article produced using the molding material to have better heat resistance and durability.

[0054] For example, the filler may include a fibrous filler. Specific examples of the fibrous filler include glass fiber, carbon fiber, rock wool, etc. Among these, it is preferable to use glass fiber.

[0055] As the fibrous filler, for example, it is preferable to use one having a number average fiber diameter of 10 μm or more and 15 μm or less and a number average fiber length of 1 mm or more and 4 mm or less, and it is more preferable to use one having a number average fiber diameter of 11 μm or more and 13 μm or less and a number average fiber length of 2 mm or more and 3 mm or less.

[0056] This ensures better workability during production of the molding material, and also makes it possible to further improve the mechanical strength of the molded article produced using the molding material.

[0057] The filler may also be particulate, more specifically, spherical filler, etc. Specific examples of spherical fillers include glass beads, glass powder, calcium carbonate, silica, aluminum hydroxide, clay, etc.

[0058] The filler content in the molding material is preferably 5.0% by mass or more and 80.0% by mass or less, more preferably 10.0% by mass or more and 75.0% by mass or less, and even more preferably 10.0% by mass or more and 75.0% by mass or less.

[0059] This makes it possible to effectively suppress various performance degradations and to make the effects of using the filler more pronounced.

[0060] [1-3]Hexamine The molding material of the present invention preferably further contains hexamine (hexamethylenetetramine).

[0061] Hexamine functions as a curing agent in the molding material, and can increase the curing speed when the molding material is heated and molded.

[0062] More specifically, when the molding material contains an alkylbenzene-modified novolac phenolic resin, the curability is reduced compared to when the molding material does not contain the alkylbenzene-modified novolac phenolic resin, but when the molding material contains hexamine, the curability of the molding material is improved, and the moldability of the molding material is also improved. Furthermore, the crosslink density of the molded article produced using the molding material can be improved, and the mechanical strength of the molded article can be improved.

[0063] When the molding material contains hexamine, the hexamine content in the molding material is preferably 0.5% by mass or more and 3.0% by mass or less, more preferably 1.0% by mass or more and 2.75% by mass or less, and even more preferably 1.5% by mass or more and 2.5% by mass or less.

[0064] This ensures better workability during the production of the molding material, and also makes the above-mentioned effects more pronounced.

[0065] [1-4] Other ingredients The molding material of the present invention may contain components other than the above-mentioned components (hereinafter referred to as other components).

[0066] Examples of other components include curing aids, release agents, stress reducing agents, lubricants, colorants, antioxidants, corrosion resistant agents, dyes, flame retardants, and elastomers.

[0067] The curing aid is a curing aid for the phenolic resin component, and examples thereof include calcium hydroxide, calcium oxide, and magnesium oxide.

[0068] Examples of the release agent include synthetic polyethylene wax, silicone wax, carnauba wax, and montanic acid wax.

[0069] Examples of the lubricant include fatty acid metal soaps such as zinc stearate, fatty acid esters, and fatty acid amides.

[0070] Examples of colorants include pigments such as carbon black, titanium oxide, barium sulfate, iron black, and red iron oxide, and dyes such as aniline black and alizanin. Examples of the flame retardant include phosphorus and aluminum hydroxide.

[0071] Examples of the elastomer include alkylacetalized polyvinyl alcohol. When the molding material contains an elastomer, the toughness of a molded article produced using the molding material can be improved.

[0072] The content of other components in the molding material is preferably 10.0% by mass or less, more preferably 7.0% by mass or less, and even more preferably 5.0% by mass or less.

[0073] [2] Manufacturing method of molding material Next, a method for producing the molding material of the present invention will be described.

[0074] The molding material of the present invention can be produced, for example, by mixing the above-mentioned components in a kneading device while heating them.

[0075] As the kneading device, for example, a two-roll mill, a three-roll mill, etc. The heating temperature and heating time during kneading are not particularly limited, and may be set to a temperature and time that are sufficient to suppress chemical reactions (deterioration) of the components being kneaded.

[0076] It is preferable to mix the components thoroughly and uniformly before kneading, and various known mixers can be used for mixing.

[0077] The kneaded material obtained using the kneading device is usually obtained in a sheet form. This sheet-like kneaded material can be pulverized to a desired particle size to obtain a powdery or granular molding material. Furthermore, the pulverized molding material may be processed into a shape such as a tablet.

[0078] [3] Manufacturing method of molded body and use of molded body Next, a method for producing a molded article using the molding material of the present invention and uses of the molded article will be described.

[0079] A molded article can be produced by curing the molding material of the present invention described above. More specifically, for example, a molded article, which is a cured product of the molding material, can be produced by a method such as transfer molding, compression molding, or injection molding using a molding material and an appropriate mold.

[0080] The uses of the molded body are not particularly limited, but examples thereof include components for various housings, various daily necessities, bicycles, automobiles, aircraft, railway vehicles, ships, office equipment, general-purpose machines, household electrical appliances, electrical equipment, etc. (for example, mechanical parts, including drive system and control system parts such as gears and brakes).

[0081] Molded articles produced using the molding material of the present invention have excellent mechanical strength and moisture resistance, and can therefore be suitably used in a variety of applications.

[0082] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these. [Example]

[0083] The present invention will be described in more detail below with reference to specific examples, but the present invention is not limited to these examples. In the following description, treatments for which no temperature conditions are specified were performed at room temperature, specifically 25°C. Furthermore, various measurement conditions for which no temperature conditions are specified are values ​​at room temperature, specifically 25°C.

[0084] [4] Manufacturing of molding materials (Examples 1 to 3, Comparative Examples 1 and 2) The material mixtures blended in the proportions shown in Table 1 were kneaded with heated rolls rotating at different speeds, cooled into a sheet, and crushed to obtain granular molding materials.

[0085] The kneading conditions for the heated rolls were as follows: rotation speed: high speed side / low speed side = 20 rpm / 14 rpm, temperature: high speed side / low speed side = 80°C / 20°C, kneading time: 3 minutes to 5 minutes.

[0086] The components used in each example and comparative example are as follows. Phenolic resin Alkylbenzene-modified novolac phenolic resin (xylene-modified novolac phenolic resin): "PR-51992" manufactured by Sumitomo Bakelite Co., Ltd. Resole phenolic resin: Sumitomo Bakelite "PR-53529" Novolac phenolic resin: Sumitomo Bakelite "PR-51305"

[0087] Curing aid Calcium hydroxide: "Super Special Hydrated Lime" manufactured by Kawai Lime Industry Co., Ltd.

[0088] Hexamine: "HEXAMINE" manufactured by CHANG CHUN PETROCHEMICAL.CO.LTD.

[0089] Filler Glass fiber: Nitto Boseki "CS3E479" Wollastonite (fibrous): NYCO "NYAD325" (number average fiber diameter: 10 μm, number average fiber length: 50 μm)

[0090] ·Mold release agent Calcium stearate: "Ca-St" manufactured by Nitto Kasei Kogyo Co., Ltd.

[0091] Pigments Carbon black: Mitsubishi Chemical "#5"

[0092] [5] Evaluation The resulting molding materials were evaluated as follows.

[0093] First, test pieces were prepared by transfer molding using the molding materials obtained in each Example and Comparative Example, each of which was cured and baked at 180°C for 4 hours, followed by another 3 hours at 220°C.

[0094] The obtained test pieces were evaluated for moisture resistance, flexural strength, flexural modulus and compressive strength, as detailed below.

[0095] [5-1] Moisture resistance The test pieces of each of the examples and comparative examples were left in a thermo-hygrostat chamber at 85°C and 85% RH for 48 hours.

[0096] After exposure to a high-temperature, high-humidity environment, the weight loss was measured using TG-DTA (Thermogravimetry-Differential Thermal Analysis) after heating from room temperature (25°C) to 180°C at a heating rate of 10°C / min under an air flow of 200 ml / min. The weight loss rate was calculated as the TG-DTA weight loss (µg) per 1 mg of the test piece and evaluated according to the following criteria.

[0097] A: The weight loss rate is less than 8.0 μg. B: The weight loss rate is 8.0 μg or more and less than 8.2 μg. C: The weight loss rate is 8.2 μg or more.

[0098] [5-2] Bending strength The bending strength of the test pieces of each example and each comparative example was measured at 25°C by a method in accordance with JIS K 6911 (2006), and evaluated according to the following criteria.

[0099] A: The bending strength is 150 MPa or more. B: The bending strength is 140 MPa or more and less than 150 MPa. C: The bending strength is less than 140 MPa.

[0100] [5-3] Flexural modulus The test pieces of each example and each comparative example were measured for flexural modulus at 25°C by a method in accordance with JIS K 6911 (2006), and evaluated according to the following criteria.

[0101] A: The flexural modulus is 22 GPa or more. B: The flexural modulus is 20 GPa or more and less than 22 GPa. C: The flexural modulus is less than 20 GPa.

[0102] [5-4] Compressive strength The compressive strength of the test pieces of each example and each comparative example was measured at 25°C by a method in accordance with JIS K 6911 (2006), and evaluated according to the following criteria.

[0103] A: Compressive strength is 270 MPa or more. B: Compressive strength is 260 MPa or more and less than 270 MPa. C: Compressive strength is less than 260 MPa.

[0104] [5-5] Hot compressive strength The compressive strength of the test pieces of each example and each comparative example was measured at 250°C by a method in accordance with JIS K 6911 (2006), and evaluated according to the following criteria.

[0105] A: Compressive strength is 90 MPa or more. B: Compressive strength is 85 MPa or more and less than 90 MPa. C: Compressive strength is less than 85 MPa. The evaluation results are summarized in Table 1.

[0106] [Table 1]

[0107] As is clear from Table 1, in the present invention, a molded article having excellent mechanical strength and moisture resistance could be obtained. In contrast, in the comparative examples, satisfactory results were not obtained.

Claims

1. A molding material containing a phenolic resin and a filler, the phenolic resin includes an alkylbenzene-modified novolac phenolic resin, A molding material characterized in that the ratio of the alkylbenzene-modified novolac phenolic resin to the total phenolic resin is 71.0 mass % or more and 99.0 mass % or less.

2. The molding material according to claim 1 , wherein the alkylbenzene-modified novolac-type phenolic resin comprises a xylene-modified novolac-type phenolic resin.

3. The molding material according to claim 1 or 2, wherein the content of the phenolic resin is 10.0% by mass or more and 35.0% by mass or less.

4. The molding material according to claim 1 or 2, further comprising hexamine.

5. The molding material according to claim 4 , wherein the content of the hexamine is 0.5% by mass or more and 3.0% by mass or less.

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