Non-fired pencil lead

Abstract

To provide an unfired pencil lead that has light resistance and coloring capacity, with minimized variations in the color tone of drawn lines over time.SOLUTION: An unfired pencil lead includes a colorant including a pigment, wax, an extender, and a water-soluble resin. The pigment includes both C.I. Pigment Yellow 74 (PY-74) and C.I. Pigment Red 254 (PR-254). In the pigment, the total proportion of the PY-74 and the PR-254 is 50 mass% or more.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to non-fired pencil leads.

Background Art

[0002] Hitherto, non-fired pencil leads such as colored pencil leads have aimed to have a smooth writing feeling, excellent coloring properties, and mechanical strength as in the technology described in Patent Document 1. On the other hand, non-fired pencil leads often contain pigments as colorants. Patent Document 2 discloses C.I. Pigment Yellow 74 as an insoluble azo dye having good storage stability of a coloring composition.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] An embodiment of the present application aims to provide a non-fired pencil lead that has light resistance and coloring power and whose line color tone hardly changes over time.

Means for Solving the Problems

[0005] The non-fired pencil lead of an embodiment of the present application contains a colorant containing a pigment, a wax, a extender material, and a water-soluble resin, the pigment contains both C.I. Pigment Yellow 74 (PY-74) and C.I. Pigment Red 254 (PR-254), and the total ratio of the PY-74 and the PR-254 in the pigment is 50% by mass or more.

[0006] In this context, it is desirable that the proportion of PR-254 in the CI pigment red pigment within the aforementioned pigment is 50% by mass or more. [Effects of the Invention]

[0007] As the embodiment of the present invention is configured as described above, it is possible to provide a non-baked pencil lead that possesses lightfastness and coloring ability, while also being less prone to changes in the color tone of the drawn lines over time. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic perspective view showing the appearance of the non-fired pencil lead of the embodiment. [Modes for carrying out the invention]

[0009] The non-fired pencil lead of the embodiment of the present invention comprises a coloring agent containing a pigment, a wax, a binder, and a water-soluble resin, wherein the pigment contains both CI Pigment Yellow 74 (PY-74) and CI Pigment Red 254 (PR-254), and the total proportion of PY-74 and PR-254 in the pigment is 50% by mass or more.

[0010] As mentioned above, the pigments include both PY-74 and PR-254. Non-fired pencil leads containing both PY-74 and PR-254 as colorants have excellent lightfastness and coloring ability, as well as the property of being resistant to discoloration over time (hereinafter referred to as "discoloration resistance").

[0011] As pigments, only PY-74 and PR-254 may be used, but other pigments, such as a mixture of one or more of CI Pigment Yellow 1 (PY-1), CI Pigment Yellow 154 (PY-154), CI Pigment Red 170 (PR-170), CI Pigment Red 48:2 (PR-48:2), CI Pigment Green 7 (PG-7), CI Pigment Blue 15 (PB-15), and CI Pigment Red 122 (PR-122), may be included, provided that the total proportion of PY-74 and PR-254 in the pigment is 50% by mass or more.

[0012] When adding CI pigment red pigments other than PR-254 (for example, PR-170, PR-48:2, PR-122) to the pigment, it is desirable that the proportion of PR-254 in the CI pigment red pigment be 50% by mass or more from the viewpoint of discoloration resistance.

[0013] In addition to the pigments mentioned above, other pigments besides PY-74 and PR-254 may include pigments commonly used for coloring colored pencils, such as graphite, titanium dioxide, iron black, carbon black, Prussian blue, ultramarine, Blue No. 1, red iron oxide, yellow iron oxide, chromium oxide, chromium hydroxide, zinc oxide, zirconium oxide, cobalt oxide, fish scale foil, bismuth oxychloride, and titanium mica, as well as azo organic pigments such as disazo yellow AAA and pyrazolone orange, cyanine organic pigments such as phthalocyanine blue and phthalocyanine green, high-grade organic pigments such as quinacridone red, dyeing pigments such as Final Color, and fluorescent pigments.

[0014] Furthermore, in addition to the pigments mentioned above, the colorants may include one or more of the following dyes: Blue No. 2, Blue No. 404, Red No. 2, Red No. 3, Red No. 102, Red No. 104, Red No. 105, Red No. 106, DPP Red, Yellow No. 4, Yellow No. 5, and Green No. 3.

[0015] Wax refers to components of non-fired pencil lead that are generally classified as wax. Specifically, rosin, paraffin wax, microcrystalline wax, lacquer wax, beeswax, Japanese wax, montan wax, hydrogenated castor oil, hydrogenated palm oil, glycerin fatty acid esters (e.g., glyceride stearate), polyglycerin fatty acid esters, etc., can be used as wax in this embodiment.

[0016] Binding materials are components that contribute to improving the strength and writing properties of non-fired pencil leads. Specifically, talc, kaolin, mica, boron nitride, calcium carbonate, potassium titanate whiskers, etc., can be used as binding materials in this embodiment.

[0017] Water-soluble resins are used as binders, and water-soluble organic polymers such as sodium carboxymethylcellulose, ammonium carboxycellulose, polyvinyl alcohol, and methylcellulose can be used.

[0018] In addition to the above, various additives may be used depending on the purpose. For example, to improve strength, cellulose fiber may be used as an additive along with the above components in the non-fired pencil lead.

[0019] The non-fired pencil lead of this embodiment can be manufactured, for example, by the following manufacturing method. That is, a coloring agent, wax, extender, water-soluble resin, and other additives as needed are mixed together, an equal amount of water is added, and the mixture is mixed and dispersed in a kneader, and then the moisture content is adjusted while kneading with two rolls. The mixture obtained by the adjustment is pelletized and extruded into the shape of a pencil lead of the desired thickness using a single-screw extruder. Then, by drying the molded lead without firing to remove the moisture, a non-fired pencil lead 10 having a substantially cylindrical core body 11, as shown in Figure 1, is obtained.

[0020] Lines written with non-fired pencil leads manufactured as described above possess both lightfastness and colorfastness, and the color tone of the lines does not change easily over time.

Example

[0021] (1) Orange non-fired pencil leads (1-1) Raw material composition Non-fired pencil leads presenting an orange color tone by containing only pigments of C.I. Pigment Yellow series and pigments of C.I. Pigment Red series as colorants were verified for lightfastness, coloring power, and color fastness to change. The raw material compositions of Examples 1 to 3 and Comparative Examples 1 and 2 described below were as shown in Table 1 below.

[0022]

Table 1

[0023] In Table 1 above, glyceryl stearate was POEM V-200 (Riken Vitamin, melting point 61°C), sodium carboxymethyl cellulose was F10MC (Nippon Paper Industries), talc was Himicron (Takehara Chemical Industry Co., Ltd.), respectively. Also, the softening point of rosin was 76°C.

[0024] (1-2) Pigment composition Details of the pigment compositions in Table 1 above for Examples 1 to 3 and Comparative Examples 1 and 2 are shown in Table 2 below. All pigments in Table 2 below are manufactured by DCL.

[0025]

Table 2

[0026] (1-3) Manufacturing method Based on the above compositions, the non-fired pencil leads of Examples 1 to 3 and Comparative Examples 1 and 2 were manufactured by the manufacturing method mentioned in the above embodiment.

[0027] The unbaked pencil leads of Examples 1-3 and Comparative Examples 1 and 2 all contained CI pigment yellow and CI pigment red pigments, and all exhibited an orange color. In Examples 1-3, depending on the ratio of PY-74 to PR-254, Example 1 exhibited a reddish orange color, Example 3 exhibited a yellowish orange color, and Example 2 exhibited an orange color intermediate between these two. Furthermore, Examples 1-3 contained both PY-74 and PR-254, and the total content of PY-74 and PR-254 in the pigment was 100% by mass and 50% by mass or more, respectively. On the other hand, Comparative Examples 1 and 2 either did not contain either PY-74 or PR-254 (Comparative Example 1), or contained only one of them (specifically PY-74) (Comparative Example 2), and were not unbaked pencil leads containing both PY-74 and PR-254.

[0028] (1-4) Evaluation Method The lightfastness and discoloration resistance of the non-fired pencil leads of Examples 1-3 and Comparative Examples 1 and 2 were evaluated. The details are as follows.

[0029] (1-4-1) Drawing lines The lines to be evaluated were prepared according to the method described in JIS S 6006:2020 8.9(a). Specifically, drawing paper (basis weight 78.3 g / m²) was used. 2 ~205g / m 2 Each non-fired pencil lead was applied by hand to a surface with a whiteness of 75% or higher, repeatedly in the left-right and up-down directions, to uniformly cover a paper surface placed on a smooth glass base.

[0030] (1-4-2) Lightfastness Lightfastness was evaluated as follows. First, the lines drawn with non-fired pencil lead as described above were checked for fastness according to JIS L 0841:2021, 7-3-c, third exposure method. Visual inspection determined that no discoloration was "A", slight discoloration was "B", and significant discoloration was "C".

[0031] (1-4-3) Discoloration resistance The discoloration resistance was evaluated as follows. First, the L*a*b* values ​​were measured using a color meter (SC-P, Suga Test Instruments Co., Ltd.) for lines drawn as described above using a non-fired pencil lead immediately after manufacturing. Next, the test paper on which these lines were drawn was stored in a dark place for one week at a temperature of 23°C and a humidity of 65%, and the L*a*b* values ​​were measured again. The ΔE value calculated from the L*a*b* values ​​before and after storage was evaluated as follows: less than 4 was rated A, and 4 or more was rated B. In other words, this discoloration resistance item evaluates how resistant the lines are to discoloration over time after they have been drawn.

[0032] (1-5) Evaluation results The evaluation results for lightfastness and discoloration resistance of the non-fired pencil leads of Examples 1-3 and Comparative Examples 1 and 2 are shown in Table 3 below.

[0033] [Table 3]

[0034] As shown in Table 3 above, Examples 1 to 3 showed excellent results with an A rating in all evaluation items. In contrast, the non-fired pencil leads of Comparative Examples 1 and 2 received inferior ratings of B or C in at least one evaluation item.

[0035] From the above, it was found that in orange-colored non-baked pencil leads, the lightfastness and discoloration resistance are improved by containing both PY-74 and PR-254 as pigments, and by having a total content of PY-74 and PY-254 in the pigments of 50% by mass or more.

[0036] (2) Non-fired pencil lead other than orange (2-1) Raw material composition The lightfastness, color strength, and discoloration resistance of non-baked pencil leads exhibiting colors other than orange were verified by incorporating pigments of other color systems as colorants in addition to CI pigment yellow and CI pigment red pigments. The raw material compositions of Examples 4 to 6 and Comparative Example 3, described below, were as shown in Table 1 above.

[0037] (2-2) Pigment composition The details of the pigment compositions in Examples 4-6 and Comparative Example 3, as shown in Table 1, are shown in Table 4 below. All pigments in Table 4 below are made of DCL.

[0038] [Table 4]

[0039] (2-3) Manufacturing method Based on the above compositions, the non-fired pencil leads of Examples 4-6 and Comparative Example 3 were manufactured by the manufacturing method described in the above embodiments.

[0040] The unbaked pencil leads of Examples 4-6 and Comparative Example 3 all contained CI pigment yellow and CI pigment red pigments, as well as pigments of other color systems, and all exhibited colors other than orange. Specifically, Examples 4 and Comparative Example 3 exhibited green due to PG-7, Example 5 exhibited light blue due to PB-15, and Example 6 exhibited reddish-purple due to PR-122. Furthermore, Examples 4-6 contained both PY-74 and PR-254, and the total content of PY-74 and PR-254 in the pigment was 50% by mass or more in all cases. On the other hand, Comparative Example 3 contained only PY-74 and was not an unbaked pencil lead containing both PY-74 and PR-254.

[0041] (2-4) Evaluation Method The lightfastness and discoloration resistance of the non-fired pencil leads of Examples 4-6 and Comparative Example 3 were evaluated. The details are as described in (1-4) above.

[0042] (2-5) Evaluation results The evaluation results for lightfastness and discoloration resistance of the non-fired pencil leads of Examples 4-6 and Comparative Example 3 are shown in Table 5 below.

[0043] [Table 5]

[0044] As shown in Table 5 above, Examples 4 to 6 showed excellent results with an A rating in all evaluation items. In contrast, the non-fired pencil lead of Comparative Example 3 received a lower rating of B or C for discoloration resistance.

[0045] From the above, it was found that even in non-baked pencil leads other than orange ones, including both PY-74 and PR-254 as pigments, and having a total content of PY-74 and PY-254 in the pigments of 50% by mass or more, improves lightfastness, colorability, and discoloration resistance.

[0046] (3) If the color is dark (3-1) Raw material composition The color changes were measured for non-fired pencil leads with a relatively high pigment content and a dark orange color. The raw material compositions for Examples 7-11 and Comparative Examples 4-8 described below were as shown in Table 1.

[0047] (3-2) Pigment composition The details of the pigment compositions in Examples 7-11 and Comparative Examples 4-8, as shown in Table 1, are shown in Table 6 below.

[0048] [Table 6]

[0049] (3-3) Manufacturing method Based on the above compositions, the non-fired pencil leads of Examples 7-11 and Comparative Examples 4-8 were manufactured by the manufacturing method described in the above embodiments.

[0050] Examples 7-11 contained both PY-74 and PR-254, and the total content of PY-74 and PR-254 in the pigment was 100% by mass and 50% by mass or more in each case. On the other hand, in Comparative Examples 4-8, PR-254 in Examples 7-11 was replaced with PR-170 in the same amount. As a result, Comparative Examples 4-8 became non-fired pencil leads containing only PY-74.

[0051] (3-4) Color measurement method The discoloration resistance of the unfired pencil leads of Examples 7-11 and Comparative Examples 4-8 was evaluated. Specifically, the L*a*b* and L*C*H* values ​​were measured using a colorimeter (SC-P, Suga Test Instruments Co., Ltd.) for lines drawn as described above using the unfired pencil leads immediately after manufacturing. Next, the test paper on which these lines were drawn was stored in a dark place for one week at a temperature of 23°C and a humidity of 65%, and the L*a*b* and L*C*H* values ​​were measured again. Then, the ΔE value was calculated from the L*a*b* values ​​before and after storage, and the ΔH value was calculated from the L*C*H* values ​​before and after storage.

[0052] (3-5) Results The color measurement results for the unfired pencil leads of Examples 7-11 and Comparative Examples 4-8 are shown in Table 7 below. Note that the L*, a*, b*, C*, and H* values ​​in the table below are only those measured before storage.

[0053] [Table 7]

[0054] As shown in Table 7 above, in all examples, the ΔE and ΔH values ​​were lower than in all comparative examples. Therefore, it was found that in dark orange non-fired pencil leads, containing both PY-74 and PY-254, and having a total content of PY-74 and PY-254 in the pigment of 50% by mass or more, makes them less susceptible to discoloration over time.

[0055] (4) When the color is moderate (4-1) Raw material composition For non-baked pencil leads with a medium-intensity orange color, where the pigment content was 1 / 4 of that in (3) above, the change in color tone was measured. In addition, in the raw material compositions of Examples 12 to 16 and Comparative Examples 13 to 17 described below, the talc content was increased by 7.5% by mass to 58.5% by mass, corresponding to the pigment content of 2.5% by mass in Table 1 above.

[0056] (4-2) Pigment composition The details of the pigment compositions in Examples 12-16 and Comparative Examples 9-13 are shown in Table 8 below.

[0057] [Table 8]

[0058] (4-3) Manufacturing method Based on the above compositions, the non-fired pencil leads of Examples 12-16 and Comparative Examples 9-13 were manufactured by the manufacturing method described in the above embodiments.

[0059] Examples 12-16 contained both PY-74 and PR-254, and the total content of PY-74 and PR-254 in the pigment was 100% by mass and 50% by mass or more in each case. On the other hand, in Comparative Examples 9-13, PR-254 in Examples 12-16 was replaced with PR-170 in the same amount. As a result, Comparative Examples 9-13 became non-fired pencil leads containing only PY-74.

[0060] (4-4) Color measurement method and results The non-fired pencil leads of Examples 12-16 and Comparative Examples 9-13 were evaluated for discoloration resistance in the same manner as described in (3-4) above. The results are shown in Table 9 below. Note that the L*, a*, b*, C*, and H* values ​​in the table below are only those measured before storage.

[0061] [Table 9]

[0062] As shown in Table 9 above, in all of the examples, the ΔE and ΔH values ​​were lower than in all of the comparative examples. Therefore, it was found that in dark orange non-fired pencil leads, containing both PY-74 and PY-254, and having a total content of PY-74 and PY-254 in the pigment of 50% by mass or more, makes them less susceptible to discoloration over time.

[0063] (5) If the color is light (5-1) Raw material composition For non-baked pencil leads with a light orange color, where the pigment content was 1 / 20 of that in (3) above, the change in color tone was measured. In addition, in the raw material compositions of Examples 17-21 and Comparative Examples 18-22 described below, the talc content was increased by 9.5% by mass to 60.5% by mass, corresponding to the pigment content of 0.5% by mass in Table 1 above.

[0064] (5-2) Pigment composition The detailed pigment compositions in Examples 17-21 and Comparative Examples 14-18 are shown in Table 10 below.

[0065] [Table 10]

[0066] (5-3) Manufacturing method Based on the above compositions, the non-fired pencil leads of Examples 17-21 and Comparative Examples 14-18 were manufactured by the manufacturing method described in the above embodiments.

[0067] Examples 17-21 contained both PY-74 and PR-254, and the total content of PY-74 and PR-254 in the pigment was 100% by mass and 50% by mass or more in each case. On the other hand, in Comparative Examples 14-18, PR-254 in Examples 17-21 was replaced with PR-170 in the same amount. As a result, Comparative Examples 14-18 became non-fired pencil leads containing only PY-74.

[0068] (5-4) Color measurement method and results The non-fired pencil leads of Examples 17-21 and Comparative Examples 14-18 were evaluated for discoloration resistance in the same manner as described in (3-4) above. The results are shown in Table 11 below. Note that the L*, a*, b*, C*, and H* values ​​in the table below are only those measured before storage.

[0069] [Table 11]

[0070] As shown in Table 11 above, in all examples, the ΔE and ΔH values ​​were lower than in all comparative examples. Therefore, it was found that in dark orange non-fired pencil leads, containing both PY-74 and PY-254, and having a total content of PY-74 and PY-254 in the pigment of 50% by mass or more, makes them less susceptible to discoloration over time.

[0071] (6) When the brightness is low (6-1) Raw material composition The color changes of unbaked orange pencil leads with reduced brightness were measured by adding small amounts of pigments from other color systems as colorants, in addition to CI pigment yellow and CI pigment red pigments. In the raw material compositions of Examples 22-24 and Comparative Examples 23-25 ​​described below, the talc content was increased by 5.5% by mass to 56.5% by mass, corresponding to the pigment content of 4.5% by mass in Table 1.

[0072] (6-2) Pigment composition The details of the pigment compositions in Examples 22-24 and Comparative Examples 19-21 are shown in Table 12 below.

[0073] [Table 12]

[0074] (6-3) Manufacturing method Based on the above compositions, the non-fired pencil leads of Examples 22-24 and Comparative Examples 19-21 were manufactured by the manufacturing method described in the above embodiments.

[0075] Examples 22-24 contained both PY-74 and PR-254, and the total content of PY-74 and PR-254 in the pigment was 88.9% by mass and 50% by mass or more in all cases. On the other hand, in Comparative Examples 19-21, PR-254 in Examples 22-24 was replaced with PR-170 in the same amount. As a result, Comparative Examples 19-21 became non-fired pencil leads containing only PY-74.

[0076] (6-4) Color measurement method and results The non-fired pencil leads of Examples 22-24 and Comparative Examples 19-21 were evaluated for discoloration resistance in the same manner as described in (3-4) above. The results are shown in Table 13 below. Note that the L*, a*, b*, C*, and H* values ​​in the table below are only those measured before storage.

[0077] [Table 13]

[0078] As shown in Table 13 above, in all examples, the ΔE and ΔH values ​​were lower than in all comparative examples. Therefore, it was found that in low-brightness orange-colored non-fired pencil leads, containing both PY-74 and PY-254, and having a total content of PY-74 and PY-254 in the pigment of 50% by mass or more, makes them less susceptible to discoloration over time.

[0079] (7) Verification of PR-254 content (7-1) Raw material composition The effect of the PR-254 content in CI pigment red was verified by measuring the change in color tone as follows. The raw material compositions for Examples 25-27 and Comparative Examples 22 and 23 described below were as shown in Table 1 above.

[0080] (7-2) Pigment composition The details of the pigment compositions in Examples 25-27 and Comparative Examples 22 and 23 are shown in Table 14 below.

[0081] [Table 14]

[0082] (7-3) Manufacturing method Based on the above compositions, the non-fired pencil leads of Examples 25-27 and Comparative Examples 22 and 23 were manufactured by the manufacturing method described in the above embodiments.

[0083] In Examples 25-27, the PR-254 content in the red pigment was 50% by mass or more. On the other hand, in Comparative Examples 22 and 23, the PR-254 content in the red pigment was less than 50% by mass.

[0084] (7-4) Color measurement method and results The non-fired pencil leads of Examples 25-27 and Comparative Examples 22 and 23 were evaluated for discoloration resistance in the same manner as described in (3-4) above. The results are shown in Table 15 below. Note that the L*, a*, b*, C*, and H* values ​​in the table below are only those measured before storage.

[0085] [Table 15]

[0086] As shown in Table 15 above, in all of the examples, the ΔE and ΔH values ​​were lower than in all of the comparative examples. Therefore, it was found that having a PR-254 content of 50% by mass or more in the red pigment makes it less susceptible to discoloration over time.

[0087] (8) Verification of the total content of PY-74 and PR-254 (8-1) Raw material composition The effect of the total content of PY-74 and PR-254 in the total content was verified by measuring the change in color as follows. The raw material compositions of Examples 8, 28, and 29 and Comparative Examples 5, 24, and 25 described below were as shown in Table 1 above. Here, Example 8 and Comparative Example 5 are the same as those mentioned in (3) above.

[0088] (8-2) Pigment composition The details of the pigment compositions in Examples 8, 28, and 29, and Comparative Examples 5, 24, and 25 are shown in Table 16 below.

[0089] [Table 16]

[0090] (8-3) Manufacturing method Based on the above compositions, the non-fired pencil leads of Examples 8, 28, and 29 and Comparative Examples 5, 24, and 25 were manufactured by the manufacturing method described in the above embodiments.

[0091] Examples 8, 28, and 29 contained both PY-74 and PR-254, and the total content of PY-74 and PR-254 in the pigment was 50% by mass or more in all cases. Comparative Example 5 contained PY-74 but did not contain PR-254. Comparative Examples 24 and 25 contained both PY-74 and PR-254, but the total content of PY-74 and PR-254 in the pigment was less than 50% by mass in all cases.

[0092] (8-4) Color measurement method and results The non-fired pencil leads of Examples 8, 28, and 29, and Comparative Examples 5, 24, and 25 were evaluated for discoloration resistance in the same manner as described in (3-4) above. The results are shown in Table 13 below. Note that the L*, a*, b*, C*, and H* values ​​in the table below are only those measured before storage.

[0093] [Table 17]

[0094] As shown in Table 17 above, in all of the examples, the ΔE and ΔH values ​​were lower than in all of the comparative examples. Therefore, it was found that when both PY-74 and PR-254 are included, the pigment is less susceptible to discoloration over time if the total content of PY-74 and PY-254 in the pigment is 50% by mass or more. [Industrial applicability]

[0095] This invention can be used as a non-fired pencil lead. [Explanation of symbols]

[0096] 10 Non-fired pencil lead 11 Lead body

Claims

1. It contains a coloring agent containing a pigment, a wax, a binder, and a water-soluble resin. The aforementioned pigment includes both C.I. Pigment Yellow 74 (PY-74) and C.I. Pigment Red 254 (PR-254). A non-fired pencil lead in which the total proportion of PY-74 and PR-254 in the pigment is 50% by mass or more.

2. The non-fired pencil lead according to claim 1, wherein the proportion of PR-254 in the C.I. pigment red pigment in the aforementioned pigment is 50% by mass or more.

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