Resin molding member

Abstract

Disclosed is a resin molding member that has excellent scratch resistance of the surface and an excellent glossy texture. The resin molding member contains a crystalline resin and further contains an inorganic filler. The resin molding member characterized by having the surface gloss of 35-75 at Gs (20°) has excellent scratch resistance of the surface and an excellent glossy texture, and, for example, it is possible to acheive a texture similar to the texture of ceramic therewith, and it is also possible to acheive integrated designs when the resin molding member is combined with ceramic to create a toilet lid or accessories thereof such as a container and a cover.

Description

Resin molded parts

[0001] The present invention relates to a resin molded part that has excellent scratch resistance and a glossy texture.

[0002] Various molded parts are made from resin materials, and their surfaces must be scratch-resistant, and for parts where appearance is important, they must have a glossy texture. Furthermore, when molded parts are used in combination with other parts, such as ceramics, it is desirable for the appearances to be similar, as this gives the product a unified design and increases its value.

[0003] Urea resins are often cited as resins that are scratch-resistant and have excellent gloss, but they may be inferior to other types of resins in terms of dimensional stability, moldability, and material cost. On the other hand, resins that are advantageous in terms of price and moldability (for example, polypropylene-based resins) may have poor scratch resistance. For such resins, in order to improve scratch resistance, it has been proposed to mix inorganic fillers such as glass fibers to increase mechanical strength (Japanese Patent Laid-Open No. 2005-188182 (Patent Document 1)), or to make the resin crystalline to increase hardness (Japanese Patent Laid-Open No. 2021-137567 (Patent Document 2)).

[0004] Japanese Patent Publication No. 2005-188182 Japanese Patent Publication No. 2021-137567

[0005] The present inventors have now discovered that by mixing an inorganic filler into a crystalline resin, a resin molded part can be obtained that has excellent surface scratch resistance and a glossy texture. The present invention is based on this discovery.

[0006] Therefore, an object of the present invention is to provide a resin molded part having excellent surface scratch resistance and a glossy texture.

[0007] The resin molded part according to the present invention is a resin molded part containing a crystalline resin and further containing an inorganic filler, and is characterized in that the surface gloss is 35 to 75 in Gs (20°).

[0008] According to the present invention, a resin molded part having excellent surface scratch resistance and a glossy texture is provided. The resin molded part according to the present invention has scratch resistance comparable to that of urea resin, and is advantageous in that it has a glossy aesthetic appearance, which can be achieved using a relatively inexpensive resin. Furthermore, the gloss can be made to resemble the appearance of pottery, and when combined with pottery in a product such as a toilet bowl and its lid, it can provide a unified design and increase the product value.

[0009] Definition of Surface Gloss: Gs(20°) and Gs(60°) In this specification, surface gloss Gs(20°) and Gs(60°) refer to the 20-degree specular gloss and 60-degree specular gloss measured according to JIS Z8741: Specular Gloss - Measurement Method. That is, in this measurement method, they refer to the gloss Gs(20°) at an incident angle of 20 degrees and the gloss Gs(60°) at an incident angle of 60 degrees.

[0010] DOI Values ​​Obtained by a Wave-Scan DOI Measuring Device As used herein, the DOI value obtained by a Wave-Scan DOI measuring device is specifically a DOI value measured by a Wave-Scan DIO (orange peel measuring device) manufactured by BYK Gardner (Germany). This device is known as a method for optically measuring the light / dark pattern of wavelengths on a target surface, similar to how the human eye does. In this microwave scan, a laser point source irradiates the sample surface with laser light at an angle of 60° from the perpendicular to the surface, and a detector measures the reflected light at the same angle but opposite to the perpendicular. This device moves the laser point source over the surface of a painted sample to scan it, thereby measuring the light / dark of the reflected light point by point at set intervals and detecting the optical profile of the sample surface. The detected optical profile is spectrally analyzed through a frequency filter, allowing the structure of the base, interior, and surface of a painted surface to be analyzed. The characteristic spectrum of this device is as follows: du: wavelength of 0.1 mm or less Wa: wavelength of 0.1 to 0.3 mm Wb: wavelength 0.3 to 1 mm Wc: wavelength 1 to 3 mm Wd: wavelength 3 to 10 mm We: wavelength 10 to 30 mm Sw: wavelength 0.3 to 1.2 mm Lw: wavelength 1.2 to 12 mm DOI: wavelength 0.3 mm or less Here, DOI is a parameter consisting of du, Wa, and Wb, and is expressed as DOI = f (du, Wa, Wb). In the present invention, the above DOI values ​​are used.

[0011] Resin Molded Part The resin molded part according to the present invention is a resin molded part comprising a crystalline resin and further comprising an inorganic filler. The resin molded part is characterized by having a surface gloss of 35 to 75 at Gs(20°). According to a preferred embodiment of the present invention, the surface gloss of the resin molded part is 40 to 65 at Gs(20°). According to another preferred embodiment, the surface gloss of the resin molded part is 70 to 89 at Gs(60°), more preferably 75 to 89. By keeping Gs(20°) and even Gs(60°) within the above ranges, the resin molded part according to the present invention has excellent surface scratch resistance and a glossy texture.

[0012] According to a preferred embodiment of the present invention, the DOI value of the surface of the resin molded part measured with a Wavescan DOI measuring device is preferably 50 to 76, more preferably 58 to 68.

[0013] The inorganic filler contained in the resin molded member according to the present invention is preferably glass fiber or mica (plate-like mineral). It is well known that inorganic fillers are incorporated into resin molded members to increase their strength. However, in the present invention, the incorporation of inorganic fillers unexpectedly has the effect of enhancing the glossy texture of the surface of the resin molded member. This texture can be similar to that of ceramics, and is preferable because combining it with ceramics in a product, such as a toilet bowl and its lid, results in a unified design and increases the product value.

[0014] In the present invention, the content of the inorganic filler may be appropriately determined within a range that achieves the above-mentioned scratch resistance and glossy texture, but according to a preferred embodiment of the present invention, it is preferably set to a range of 5 to 35% by mass, more preferably 10 to 30% by mass. By setting the content of the inorganic filler within these ranges, good scratch resistance and glossy texture can be obtained. In particular, with regard to gloss, by setting the inorganic filler within the above range, a resin molded part with excellent texture can be obtained without imparting excessive gloss.

[0015] In the present invention, the size and shape of the inorganic filler may be determined as appropriate within a range in which the above-mentioned scratch resistance and glossy texture can be obtained, but according to a preferred embodiment of the present invention, the shape is fibrous, with a diameter of about 6 μm to 24 μm and a length of about 10 μm to 3000 μm.

[0016] According to a preferred embodiment of the present invention, the crystalline resin contained in the resin molded part has a crystallinity of 50% or more in its outermost layer, and the crystallinity of this outermost layer is preferably maintained up to a depth of at least 9.0 μm from the outermost layer, i.e., the outermost surface of the part.

[0017] In the above-mentioned embodiment, the crystallinity of a resin refers to the ratio of crystalline portions in a crystalline resin, and its measurement method is well known. For example, methods for measuring crystallinity include density analysis, thermal analysis, NMR analysis, and IR analysis. In the present invention, the crystallinity is preferably measured by X-ray diffraction. That is, a resin molded part is irradiated with X-rays, and the obtained diffraction information is used to separate the scattering region originating from crystals and the scattering region originating from non-crystals. The ratio of the crystalline scattering intensity to the total scattering intensity is calculated, and this is taken as the crystallinity.

[0018] In the present invention, "the crystallinity of the outermost layer is maintained" means that the crystallinity value is the same from the outermost surface of the component to a depth of at least 9.0 μm, and that the change in crystallinity compared to the outermost layer to a depth of at least 9.0 μm remains within a range of about ±7%, preferably ±5%.

[0019] By maintaining the predetermined crystallinity from the outermost surface of the component to a depth of at least 9.0 μm, the component surface is resistant to scratches and has the properties required for a resin molded component, namely, excellent strength and durability, and small dimensional change after molding. The present invention is advantageous in that it can produce a resin component that is good in properties that are generally reduced by resin crystallization.

[0020] According to a preferred embodiment of the present invention, the crystallinity of the outermost layer is 50% or more, more preferably 70% or more, and the crystallinity of the outermost layer is maintained to a depth of at least 9.0 μm, more preferably to a depth of at least 50 μm.

[0021] Examples of crystalline resins that can be used as molded parts according to the present invention include polypropylene (PP), polybutylene terephthalate (PBT), polyethylene (PE), polyamide (PA), polyacetal, polyoxymethylene (POM), polyethylene terephthalate (PET), polyether ether ketone (PEEK), polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), etc. Note that in the present invention, urea resins are not classified as crystalline resins and are excluded.

[0022] The molded member according to the present invention is preferably used as a wet area member. In the present invention, a wet area member means a member that is exposed to water and then wiped off, and / or a member that is frequently cleaned with water and then wiped off. The molded member according to the present invention has excellent scratch resistance on its surface, so that the occurrence of scratches on the surface due to the operation of wiping off water from the surface of the member is suppressed. As a result, the molded member can be used for a long period of time without impairing the surface design of the molded member.

[0023] Specific examples of molded parts according to the present invention include toilet seats; toilet lids; case covers for warm-water washing toilet seats; resin parts for remote controls; side panels for toilets; resin parts for paper holders; resin parts for bathroom counters, bath aprons, washbasins, and the surrounding areas of hand washing basins; resin parts for handles and accessory boxes in kitchen storage areas; and resin parts for hand dryers.

[0024] According to one preferred embodiment of the present invention, the molded resin component is a toilet lid. A toilet lid has an upper surface exposed upward when closed and a lower surface exposed downward, and both surfaces are required to be scratch-resistant. Therefore, in this toilet lid, the outermost surface of the component preferably refers to both the upper and lower surfaces, and it is preferable that both surfaces satisfy the requirements of the present invention. Furthermore, as described above, the texture of the molded resin component according to the present invention can be made similar to that of ceramics, and by combining it with ceramics to form a toilet lid or a container or cover for its accessory equipment, a unified design can be achieved.

[0025] Manufacturing Method The molded part according to the present invention is manufactured by a method capable of controlling the crystallization of the crystalline resin, preferably by the following method. That is, the resin mixed with an inorganic filler heated to its melting temperature is filled into a mold heated to a temperature within ±10°C of the crystallization temperature of the resin, and the mold is held in the mold for at least 20 seconds. After the mold is cooled, the molded resin part is obtained. Here, the crystallization temperature of the resin can be derived by the following method, for example, differential scanning calorimetry (DSC measurement). The crystalline resin is heated to a temperature above its melting point, and after the resin is completely melted, the resin is cooled at a rate of, for example, about 5°C / min. During cooling, an exothermic peak associated with crystallization is observed, and the temperature of this peak is taken as the crystallization temperature.

[0026] According to one aspect of the present invention, when the resin is a PP resin, the mold is heated to a temperature of 110°C or higher and 130°C or lower, and the mold is filled with the resin heated to a temperature equal to or higher than the mold temperature. Here, according to a preferred aspect of the present invention, the resin temperature is 180°C to 220°C or higher, more preferably about 190°C. After the resin is filled into the mold, the mold is heated if necessary to a temperature in the range of 110°C to 130°C, and the pressure is maintained for at least 20 seconds, preferably 40 seconds or higher, and more preferably 60 seconds or less, and then the molded part is obtained after heat dissipation or cooling.

[0027] The present invention will be further illustrated by the following examples, but the present invention is not limited to these examples.

[0028] Resin Materials Used: Polypropylene (PP) resin used in the following examples and comparative examples was prepared using a PP resin with an MFR (temperature 230°C, load 2.16 kgf) of 19 g / 10 min conforming to JIS K-7210. The following amounts of glass fiber were mixed in to prepare resin pellets 1 to 3. Resin Pellet 1 (containing 10% by mass of glass fiber (GF)): 10% by mass of glass fiber (GF) was added to the prepared PP resin, and the mixture was melt-kneaded using an extruder to prepare resin pellet 1. Resin Pellet 2 (containing 20% ​​by mass of glass fiber (GF)): 20% by mass of glass fiber (GF) was added to the prepared PP resin, and the mixture was melt-kneaded using an extruder to prepare resin pellet 2. Resin Pellet 3 (containing 30% by mass of glass fiber (GF)): 30% by mass of glass fiber (GF) was added to the prepared PP resin, and the mixture was melt-kneaded using an extruder to prepare resin pellet 3. Reference Example Resin Pellets The prepared PP resin was melt-kneaded using an extruder without adding glass fiber to prepare reference example resin pellets.

[0029] Examples 1 to 3: Toilet lids were produced by injection molding using resin pellets 1 to 3 under the following conditions: The resin pellets were heated to 190°C and filled into a mold heated to 120°C. The mold temperature was then maintained at 120°C for 40 seconds, and after allowing to cool, the toilet lid was removed from the mold.

[0030] Comparative Examples 1 to 3: Toilet lids were produced by injection molding using resin pellets 1 to 3 under the following conditions: The resin pellets were heated to 190°C and filled into a mold heated to 40°C, after which the heating of the mold was stopped and the toilet lid was removed from the mold after 20 seconds.

[0031] Reference Example 1 Using the reference resin pellets, toilet lids were produced under the same conditions as in Examples 1 to 3.

[0032] Reference Example 2 A toilet lid (manufactured by TOTO Co., Ltd.) was prepared by press-molding a urea resin.

[0033] Measurement of Crystallinity The crystallinity of the toilet lid of the Reference Example was measured using the following measuring device and conditions: Analytical device: SmartLab manufactured by Rigaku Corporation X-ray source: CuKα (45 kV-200 mA) Optical system: Out-of-plane (incident angle: 0.3, 1, 2, 3, 5°) Stage: RxRy attachment head Detector: HyPix-3000 Scan mode: 0-dimensional Scan speed: 3.5° min-1 Step width: 0.056° Scan axis: 2θ Scan range: 5 to 40° Entrance slit box: 0.072 mm Length limiting slit: 10 mm Receiving slit box 1: 1.0 mm Receiving slit box 2: 1.1 mm

[0034] The X-ray incident angle (ω) was changed from 0.3 to 5 degrees, which corresponds to an analysis depth (X-ray penetration depth) of 2.4 μm to 46.0 μm.

[0035] The areas of the crystalline and non-crystalline parts were determined from the X-ray diffraction patterns obtained at each X-ray incident angle, and the crystallinity was calculated using the following formula: Crystallinity (%) = [(area of ​​crystalline part) / (area of ​​crystalline part + area of ​​non-crystalline part)] x 100

[0036] The measured depth from the surface and the degree of crystallinity were as shown in Table 1 below.

[0037] Evaluation of Scratch Resistance: Pencil Hardness Pencil hardness tests were conducted on the toilet lids obtained in Examples 1 to 3 and Comparative Examples 1 to 3 and the toilet lids of Reference Examples 1 and 2 in accordance with JIS K 5600-5-4:1999. For pencil hardnesses of less than 6B not specified in JIS K 5600-5-4:1999, the Hi-uni series manufactured by Mitsubishi Pencil Co., Ltd. was used. The results were as shown in Table 2 below.

[0038] Evaluation of Surface Gloss The DOI values ​​of the toilet lids obtained in Examples 1 to 3 and Comparative Examples 1 to 3, as well as Reference Examples 1 and 2, were measured using a Wave-Scan DIO (orange peel measuring device) manufactured by BYK Gardner (Germany). The results are shown in Table 2 below. However, for Comparative Examples 1 to 3, the DOI values ​​were below the lower measurement limit (30).

[0039] Elastic Modulus: Strip-shaped test specimens were molded in accordance with JIS K7152 under the same conditions as in Examples 1 to 3, Comparative Examples 1 to 3, and Reference Example 1. A strip-shaped test specimen for Reference Example 2 was also prepared. The flexural modulus of these strip-shaped test specimens was evaluated in a room temperature environment in accordance with JIS K7171. The results are shown in Table 2 below.

[0040]

Claims

1. A resin molding member comprising a crystalline resin, further comprising an inorganic filler, and having a gloss on its surface of 35 to 75 at Gs(20°).

2. The resin molding member according to claim 1, wherein the crystallinity in the outermost layer is 50% or more, and the crystallinity of the outermost layer is maintained up to a depth of at least 9.0 μm from the outermost layer.

3. The resin molding member according to claim 1 or 2, having a gloss on its surface of 40 to 65 at Gs(20°).

4. The resin molding member according to any one of claims 1 to 3, having a gloss on its surface of 70 to 89 at Gs(60°).

5. The resin molding member according to any one of claims 1 to 4, having a gloss on its surface of 75 to 89 at Gs(60°).

6. The resin molding member according to any one of claims 1 to 5, having a DOI value measured by a wave scan DOI measuring device on its surface of 50 to 76.

7. The resin molding member according to any one of claims 1 to 6, wherein the DOI value is 58 to 68.

8. The resin molding member according to any one of claims 1 to 7, wherein the content of the inorganic filler is 5 to 35% by mass.

9. The resin molding member according to any one of claims 1 to 8, wherein the inorganic filler is glass fiber or mica.

10. The resin molding member according to any one of claims 1 to 9, wherein the crystalline resin is at least one selected from the group consisting of polypropylene (PP), polybutylene terephthalate (PBT), polyethylene (PE), polyamide (PA), polyacetal, polyoxymethylene (POM), polyethylene terephthalate (PET), polyether ether ketone (PEEK), polyphenylene sulfide (PPS), and polytetrafluoroethylene (PTFE).

11. The resin molding member according to any one of claims 1 to 10, which is a toilet lid.

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