Writing implement component and writing implement

Abstract

A resin part 110 for a writing implement according to the present invention contains an acrylonitrile–butadiene–styrene resin composition. The acrylonitrile–butadiene–styrene resin composition contains an ultraviolet absorber for a UV-A region, an ultraviolet absorber for a UV-B region, and a light stabilizer.

Description

Writing instrument parts and writing instruments

[0001] The present invention relates to a writing instrument part and a writing instrument using the writing instrument part.

[0002] Extending the lifespan of writing instruments has been attracting attention as an environmental initiative. Writing instruments are composed of various resin parts, each of which is required to have various performance characteristics. For example, clips and other components require mechanical strength, such as bending strength, to prevent breakage during use, and acrylonitrile-butadiene-styrene resin (ABS resin) compositions that can meet these performance requirements are widely used. However, ABS resin compositions can discolor and undergo brittle fracture when used for extended periods of time.

[0003] Regarding extending the life of resins, Patent Document 1 discloses a thermoplastic resin composition in which, relative to 100 parts by mass of a rubber-reinforced thermoplastic resin (A) containing a rubber polymer (A), the total amount of a phenolic antioxidant (a), a hindered amine light stabilizer (b), and a phosphorus-based antioxidant (c) is 0.5 to 3.5 parts by mass, the amount of a benzotriazole-based ultraviolet absorber (d) is 0.25 to 0.75 parts by mass, and the amount of an ethylene-carbon monoxide-(meth)acrylic acid ester copolymer (e) is in the range of 0.5 to 6.0 parts by mass, and the weight ratios of the phenolic antioxidant (a), the hindered amine light stabilizer (b), and the phosphorus-based antioxidant (c) to the weight ratio of the rubber polymer (A) to 100 parts by mass of the rubber-reinforced thermoplastic resin (A) satisfy a predetermined relationship. According to the thermoplastic resin composition of Patent Document 1, it is said that a thermoplastic resin composition can be obtained that has the general properties required in wet environments, namely, chemical resistance, resistance to yellowing in the dark, and resistance to thermal discoloration after retention, as well as excellent resistance to yellowing in the dark upon contact with detergent.

[0004] JP 2014-098113 A

[0005] To extend the life of writing instruments, it is desirable to suppress discoloration and brittle fracture over time in resin parts for writing instruments containing ABS resin compositions. However, although it is known that such resin parts for writing instruments discolor and undergo brittle fracture over time, the causes of discoloration and brittle fracture have not been clear because the environments in which writing instruments are used are extremely diverse. Therefore, it has not been possible to suppress both discoloration and brittle fracture in resin parts for writing instruments while taking advantage of the properties of ABS resin.

[0006] Therefore, an object of the present invention is to provide a resin part for a writing instrument that contains an ABS resin composition and that can suppress discoloration over time while also suppressing brittle fracture.

[0007] After extensive investigation, the present inventors have found that the above-mentioned problems can be solved by the following means, and have thus completed the present invention. That is, the present invention is as follows: <Aspect 1> A resin part for a writing instrument comprising an acrylonitrile-butadiene-styrene resin composition, wherein the acrylonitrile-butadiene-styrene resin composition comprises the following: an acrylonitrile-butadiene-styrene resin, an ultraviolet absorber for the UV-A region, an ultraviolet absorber for the UV-B region, and a light stabilizer. <Aspect 2> A resin part for a writing instrument according to Aspect 1, wherein the acrylonitrile-butadiene-styrene resin composition comprises the following: 100 parts by mass of the acrylonitrile-butadiene-styrene resin, 0.30 to 1.0 parts by mass of the ultraviolet absorber for the UV-A region, 0.15 to 0.5 parts by mass of the ultraviolet absorber for the UV-B region, and 0.01 to 0.4 parts by mass of the light stabilizer. Aspect 3: A writing instrument comprising the resin part for a writing instrument according to Aspect 1 or 2.

[0008] According to the present invention, it is possible to provide a resin part for a writing instrument that can suppress discoloration and brittle fracture even when an ABS resin composition is used.

[0009] 1(a) to 1(c) are a plan view, a front view, and a longitudinal sectional view, respectively, of a writing instrument having a writing instrument component according to an embodiment of the present invention.

[0010] The writing instrument component of the present invention is a resin part for a writing instrument that contains an acrylonitrile-butadiene-styrene (ABS) resin composition. The ABS resin composition also contains an ultraviolet absorber for the UV-A region, an ultraviolet absorber for the UV-B region, and a light stabilizer.

[0011] The configuration of a writing instrument 100 having a writing instrument component of the present invention will be briefly described with reference to Figure 1. In this embodiment, a knock-type ballpoint pen is shown. Note that the present invention is not limited to this embodiment, and various modifications can be made within the scope of the gist of this disclosure.

[0012] 1(a) to 1(c) are a plan view, a front view, and a longitudinal cross-sectional view, respectively, of a writing instrument 100 according to an embodiment of the present invention. As shown in Fig. 1, in this specification, the tip, i.e., the nib side, of the writing instrument 100 is defined as the "front" side of the writing instrument 100, and the side opposite the nib of the writing instrument 100 along the axial direction (longitudinal direction) of the writing instrument 100 is defined as the "rear" side of the writing instrument 100.

[0013] The writing instrument 100 comprises a rear barrel 120 which is integral with the clip 126, a front barrel 130 which is arranged in front of the rear barrel 120, a grip 140 formed on the outer surface of the front barrel 130, a knock cover 150 which is arranged at the rear end of the writing instrument 100, a cutlery 160 which is arranged at the front end of the writing instrument 100, a rotor 170 housed inside the rear barrel 120, and a writing core portion 180 which extends in front of the rotor 170.

[0014] The front barrel 130 and grip 140, as well as the rear barrel (primary molded portion) 122 and rear barrel (secondary molded portion) 124 are molded in two colors.

[0015] The writing core 180 is composed of a spring 182 that biases the writing core 180 rearward, an ink reservoir 184 that contains ink, and a ballpoint pen tip 186 at the front end. The knock cover 150 is moved back and forth with a finger to cause the ballpoint pen tip 186 to protrude and retract from the cutlery 160.

[0016] As described above, the cause of aging discoloration and brittle fracture of ABS resin compositions in resin parts for writing instruments had not been clarified until now. However, the present inventors have found, as a result of durability tests in various test environments, that ultraviolet light in a high-temperature, high-humidity environment is the cause of discoloration and brittle fracture of ABS resin compositions in resin parts for writing instruments.

[0017] Based on the above findings, the present inventors investigated resin parts for writing instruments that can suppress discoloration over time. Specifically, by incorporating an ultraviolet absorber for the UV-A region, an ultraviolet absorber for the UV-B region, and a light stabilizer into an ABS resin composition, discoloration and brittle fracture of the resin parts for writing instruments containing the ABS resin composition could be suppressed.

[0018] Each component of the present invention will be described below.

[0019] The writing instrument part of the present invention is a resin part for a writing instrument that contains an ABS resin composition.

[0020] Although there are no particular limitations on the application of the writing implement part of the present invention, it is preferable that the writing implement part be a clip, which is prone to discoloration and brittle fracture over time.

[0021] The clip's colorfastness is measured by exposing the clip to ultraviolet light at an irradiance of 320 W / m ２ When irradiated with light at 100° C. for 100 hours, the color difference ΔE*ab in the CIELab color system is preferably less than 5.0, less than 4.0, less than 3.0, less than 2.5, or less than 2.0.

[0022] The durability of the clip is measured by exposing the clip to ultraviolet light at an irradiance of 320 W / m ２ When irradiated with UV light for 100 hours, the elongation at the breaking point of the clip in a tensile test in accordance with JIS-K7113 is preferably 5% or more, 6% or more, 7% or more, 8% or more, 9% or more, or 10% or more, and is preferably 20% or less, 18% or less, 16% or less, or 15% or less.

[0023] The method for molding the ABS resin composition is not particularly limited, but injection molding is preferred from the viewpoint of producing writing implement parts.

[0024] <ABS Resin> The ABS resin composition contains an ABS resin, and the ABS resin can be prepared by selecting any monomer composition ratio and bonding method of acrylonitrile, butadiene, and styrene.

[0025] As the ABS resin, various commercially available ABS resins such as ABS170 and ABS130 (manufactured by Techno UMG Co., Ltd.) can be used.

[0026] <Ultraviolet Absorber> The ABS resin composition contains an ultraviolet absorber for the UV-A region and an ultraviolet absorber for the UV-B region.

[0027] In the present invention, the term "ultraviolet absorber for the UV-A region" refers to an ultraviolet absorber having a peak absorption wavelength in the UV-A region (long-wavelength ultraviolet region: 315 nm to 400 nm) of the ultraviolet region (200 nm to 400 nm), and the term "ultraviolet absorber for the UV-B region" refers to an ultraviolet absorber having a peak absorption wavelength in the UV-B region (mid-wavelength ultraviolet region: 280 nm to 315 nm) of the ultraviolet region.

[0028] The blending amount of the UV-A region ultraviolet absorber is preferably 0.30 parts by mass or more, 0.40 parts by mass or more, 0.50 parts by mass or more, 0.60 parts by mass or more, 0.70 parts by mass or more, or 0.80 parts by mass or more, relative to 100 parts by mass of the ABS resin, from the viewpoint of ensuring weather resistance, and is preferably 3.00 parts by mass or less, 2.50 parts by mass or less, 2.00 parts by mass or less, 1.50 parts by mass or less, 1.40 parts by mass or less, 1.30 parts by mass or less, 1.20 parts by mass or less, 1.10 parts by mass or less, or 1.00 parts by mass or less, from the viewpoint of ensuring the mechanical strength of the ABS resin composition.

[0029] The blending amount of the ultraviolet absorber for the UV-B region is preferably 0.15 parts by mass or more, 0.20 parts by mass or more, 0.25 parts by mass or more, 0.30 parts by mass or more, 0.35 parts by mass or more, 0.40 parts by mass or more, 0.45 parts by mass or more, or 0.50 parts by mass or more, relative to 100 parts by mass of the ABS resin, from the viewpoint of ensuring weather resistance, and is preferably 2.00 parts by mass or less, 1.50 parts by mass or less, 1.00 parts by mass or less, 0.80 parts by mass or less, 0.70 parts by mass or less, or 0.60 parts by mass or less, relative to 100 parts by mass of the ABS resin, from the viewpoint of ensuring the mechanical strength of the ABS resin composition.

[0030] The ultraviolet absorbers for the UV-A and UV-B regions can be selected from, for example, triazine-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, and benzophenone-based ultraviolet absorbers depending on their ability to absorb ultraviolet light. Multiple types of ultraviolet absorbers may also be used in combination.

[0031] As the triazine-based ultraviolet absorber, for example, 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[2-(2-ethylhexanoyloxy)ethoxy]phenol, which has high absorption capacity in the ultraviolet region of 280 to 300 nm, can be used as an ultraviolet absorber for the UV-B region, and 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1,3,5-triazine, which has high absorption capacity in the ultraviolet region of around 350 to 380 nm, can be used as an ultraviolet absorber for the UV-A region.

[0032] As a benzotriazole-based ultraviolet absorber, for example, 2-(5-chloro-2H-benzotriazol-2-yl)-6-tert-butyl-4-methylphenol, which has high absorption capacity in the ultraviolet region of 340 to 360 nm, can be used as an ultraviolet absorber for the UV-A region.

[0033] As a benzophenone-based ultraviolet absorber, for example, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, which has a high absorption capacity in the ultraviolet region of 340 to 360 nm, can be applied as an ultraviolet absorber for the UV-A region.

[0034] <Light Stabilizer> The ABS resin composition contains a light stabilizer.

[0035] The light stabilizer captures radicals generated by photodegradation, and may be, for example, a hindered amine light stabilizer, a hindered phenol antioxidant, a phenol radical scavenger, a sulfur-based antioxidant, a phosphorus-based antioxidant, a triazine-based compound, a benzotriazole-based compound, a phenol-based ultraviolet absorber, a malonic acid ester-based ultraviolet absorber, an oxanilide-based ultraviolet absorber, or a benzophenone-based compound, with a hindered amine light stabilizer being particularly preferred.

[0036] Examples of the hindered amine light stabilizer include monomeric light stabilizers such as bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate, bis(N-methyl-2,2,6,6-tetramethyl-4-piperidinyl)sebacate, 4-benzoyloxy-2,2',6,6'-tetramethylpiperidine, and bis(1,2,2,6,6-pentamethyl-4-piperidyl){[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl}butylmalonate; )imino-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]hexamethylene[(2,2,6,6-tetramethyl-4-piperidyl)iminol]}, light stabilizers having a polyester bond such as a polyesterification product of 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol and succinic acid, or light stabilizers having a polymerizable unsaturated group such as 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate and 2,2,6,6-tetramethyl-4-piperidyl methacrylate can be used.

[0037] Commercially available hindered amine light stabilizers include, for example, "Tinuvin 765," "Tinuvin 770DF," "Tinuvin 144," "Tinuvin 622SF," and "Tinuvin 152" (all of which are product names manufactured by BASF Corporation, and Tinuvin is a registered trademark), "ADK STAB LA-52," "ADK STAB LA-57," "ADK STAB LA-63P," "ADK STAB LA-72," "ADK STAB LA-77Y," "ADK STAB LA-81," "ADK STAB LA-82," and "ADK STAB LA-87" (all of which are product names manufactured by ADEKA Corporation, and ADK STAB is a registered trademark), and the like.

[0038] The amount of the light stabilizer to be added is preferably 0.01 part by mass or more, 0.03 part by mass or more, 0.05 part by mass or more, 0.06 part by mass or more, 0.07 part by mass or more, 0.08 part by mass or more, 0.09 part by mass or more, or 0.10 part by mass or more, per 100 parts by mass of the ABS resin, from the viewpoint of suppressing an increase in brittleness of the ABS resin composition over time, and is preferably 0.50 parts by mass or less, 0.40 parts by mass or less, 0.30 parts by mass or less, 0.20 parts by mass or less, 0.19 parts by mass or less, 0.18 parts by mass or less, or 0.17 parts by mass or less. Addition of an excessive amount of light stabilizer may impair discoloration resistance.

[0039] <Antioxidant> The ABS resin composition may contain an antioxidant.

[0040] The antioxidant may be, for example, 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane.

[0041] The amount of antioxidant blended is preferably 0.10 part by mass or more, 0.12 part by mass or more, 0.14 part by mass or more, 0.15 part by mass or more, 0.16 part by mass or more, 0.18 part by mass or more, or 0.20 part by mass or more, relative to 100 parts by mass of the ABS resin, from the viewpoint of ensuring weather resistance, and is preferably 1.00 part by mass or less, 0.80 part by mass or less, 0.70 part by mass or less, 0.60 part by mass or less, 0.55 part by mass or less, or 0.50 part by mass or less, relative to 100 parts by mass of the ABS resin, from the viewpoint of ensuring the mechanical strength of the ABS resin composition.

[0042] <Pigment> The ABS resin composition may contain a pigment, and may use a colorant such as a dry color, a paste color, a color compound, a masterbatch, etc. Alternatively, the ABS resin composition may not contain a pigment.

[0043] The weight content of the colorant is preferably less than 5 parts by mass relative to 100 parts by mass of the ABS resin composition, from the viewpoint of ensuring the mechanical strength of the ABS resin composition.

[0044] Examples of the pigment that can be used include organic pigments, inorganic pigments, luster pigments, and dyes.

[0045] Examples of the organic pigment that can be used include azo pigments, lake pigments, phthalocyanine pigments, quinacridone pigments, dioxazine pigments, perylene red pigments, and isoindolinone pigments.

[0046] Examples of the inorganic pigment that can be used include black iron oxide, yellow iron oxide, red iron oxide, chromium oxide, titanium oxide, carbon black, and ultramarine.

[0047] As the above-mentioned bright pigment, for example, aluminum powder, synthetic mica, natural mica, etc. can be used.

[0048] <Writing Instrument> The writing instrument of the present invention includes the above-described resin part for a writing instrument.

[0049] The ABS resin composition can be applied to a writing instrument as a writing instrument component by molding it into one or more resin parts for the writing instrument.

[0050] The present invention will be specifically explained with reference to examples and comparative examples, but the present invention is not limited to these.

[0051] <<Preparation of Writing Instrument Parts>> In Examples 1 to 4 and Comparative Examples 1 to 8, the additives shown in Table 1 were added to ABS resin, and the mixture was injection molded to prepare clips for writing instruments.

[0052] <Evaluation> <Evaluation of Discoloration Resistance> In Examples 1 to 4 and Comparative Examples 1 to 8, plate-shaped test pieces were prepared for checking the hue. The test pieces were irradiated with ultraviolet light using a fade meter (X25, manufactured by Suga Test Instruments Co., Ltd.) at an irradiance of 320 W / m ２ The color hue in the CIELab color system before and after irradiation was measured using a color meter (SP-C, manufactured by Suga Test Instruments Co., Ltd.), and the color difference ΔE*ab was calculated to evaluate discoloration resistance. A: ΔE*ab is less than 2.0 B: ΔE*ab is 2.0 or more but less than 5.0 C: ΔE*ab is 5.0 or more

[0053] <Evaluation of Brittleness> Test specimens of Examples 1 to 4 and Comparative Examples 1 to 8 were prepared, and the test specimens were irradiated with ultraviolet light using a fade meter (X25, manufactured by Suga Test Instruments Co., Ltd.) at an irradiance of 320 W / m ２The test pieces were subjected to a tensile test in accordance with JIS-K7113 after irradiation, and the elongation at the breaking point was measured and evaluated. A: Elongation at the breaking point was 5% or more B: Elongation at the breaking point was 3% or more and less than 5% C: Elongation at the breaking point was less than 3%

[0054] The evaluation results are shown in Table 1.

[0055] From Examples 1 to 4 and Comparative Example 2 in Table 1, it can be seen that when a UV-B ultraviolet absorber and a light stabilizer are added to an ABS resin but no UV-A ultraviolet absorber is added, the increase in brittleness over time cannot be improved.

[0056] From Examples 1 to 4 and Comparative Examples 3 to 5 in Table 1, it can be seen that when a UV-A ultraviolet absorber and a light stabilizer are added to an ABS resin but no UV-B ultraviolet absorber is added, the deterioration of discoloration resistance over time cannot be improved.

[0057] From Examples 1 to 4 and Comparative Example 6 in Table 1, it can be seen that when a UV-A ultraviolet absorber and a UV-B ultraviolet absorber are added to an ABS resin without adding a light stabilizer, the deterioration in discoloration resistance and the increase in brittleness over time cannot be improved.

[0058] Therefore, it can be understood that resin parts for writing instruments made from ABS resin to which UV-A ultraviolet absorbers, UV-B ultraviolet absorbers, and light stabilizers have been added have properties that make them less susceptible to discoloration and brittle fracture over time.

[0059] 100 Writing implement 110 Resin parts for writing implement 120 Rear barrel 122 Rear barrel (primary molded part) 124 Rear barrel (secondary molded part) 126 Clip 130 Front barrel 140 Grip 150 Knock cover 160 Cutipla 170 Rotor 180 Writing core 182 Spring 184 Ink reservoir 186 Ballpoint pen tip

Claims

1. A resin part for a writing instrument comprising an acrylonitrile-butadiene-styrene resin composition, wherein the acrylonitrile-butadiene-styrene resin composition comprises the following: an acrylonitrile-butadiene-styrene resin, an ultraviolet absorber for the UV-A region, an ultraviolet absorber for the UV-B region, and a light stabilizer.

2. The resin part for a writing instrument according to claim 1, wherein the acrylonitrile-butadiene-styrene resin composition comprises: (1) 100 parts by weight of the acrylonitrile-butadiene-styrene resin; (2) 0.30 to 1.00 parts by weight of the ultraviolet absorber for the UV-A region; (3) 0.15 to 0.50 parts by weight of the ultraviolet absorber for the UV-B region; and (4) 0.01 to 0.40 parts by weight of the light stabilizer.

3. A writing instrument comprising the resin part for a writing instrument according to claim 1 or 2.

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