Cu-Cr-Zn-O composite oxide pigment

Abstract

In view of the above background, the present invention provides a Cu—Cr—O composite oxide pigment having excellent color characteristics and improved durability. The present invention relates to a Cu—Cr—Zn—O composite oxide pigment in which Zn derived from zinc oxide added as a modifying oxide is dissolved in a Cu—Cr—O composite oxide, and which has an oxide composition formula: aCuO·bCr2O3·cZnO (mol%), where 0.1 ≤ c ≤ 5, 45 ≤ a + c ≤ 55, and 45 ≤ b ≤ 55 (a + b + c = 100).

Description

Technical Field

[0001] The present invention relates to a Cu-Cr-O composite oxide pigment as a black pigment. Background Art

[0002] Among pigments used as colorants, there are composite oxide pigments composed of solid solutions formed by combining two or more oxides. Composite oxide pigments are generally extremely stable chemically and physically, and thus are excellent in weather resistance, acid resistance, and heat resistance, and are widely used in applications requiring durability such as coatings, building materials, and resins.

[0003] The composite oxide pigment C.I. Pigment Black 28 registered in the Colour Index specified by The Society of Dyers and Colourists (SDC) and The American Association of Textile Chemists and Colorists (AATTC) is a blue-toned black pigment having a spinel structure composed of Cu and Cr, and is a pigment with very high fastness excellent in chemical resistance, heat resistance, and weather resistance.

[0004] As uses of this pigment, in addition to coatings, plastics, enamels, and glass colors, it can also be used in super-durable fluorine coatings and heat-resistant coatings to exhibit its high fastness. In addition, recently, it has also been used in Laser Direct Structuring (LDS) applications, and is very diverse.

[0005] In the manufacturing method of the Cu-Cr-O composite oxide pigment, there are a dry method of uniformly mixing copper oxide and chromium oxide raw materials using a stirrer or a ball mill to produce a mixture (batch), or a wet method of reacting an aqueous solution of Cu and Cr with an alkaline aqueous solution to form a composite metal hydroxide or oxide composed of Cu and Cr to produce a batch. Any of the above methods can finally obtain a pigment by firing the produced batch and pulverizing the fired product.

[0006] In the method of producing a batch, the dry method is basically selected from multiple viewpoints such as simple manufacturing method, low production cost, and no need for wastewater treatment.

[0007] However, when the batch composed of copper oxide and chromium oxide produced by the dry method is fired, the reactivity in the solid-phase reaction is low, and as a result, a pigment with sufficient blackness cannot be obtained.

[0008] In addition, when firing is carried out at a higher temperature for the purpose of improving the reactivity of the batch in the solid-phase reaction, spinel-structured CuCr 2 O 4 decomposes at a certain temperature above a certain level, generating CuCrO 2 . As a result, the blackness and durability of the pigment are reduced.

[0009] To solve such problems, when preparing a batch by using the dry method as a manufacturing method for a composite oxide pigment, in addition to copper oxide and chromium oxide raw materials, manganese compounds such as manganese dioxide or manganese sesquioxide are usually added as modifying oxides, and the pigment composition is designed as a Cu-Cr-Mn-O composite oxide. If the pigment composition is designed as a Cu-Cr-Mn-O composite oxide, a pigment with sufficient blackness and coloring power can also be obtained when preparing the batch by the dry method.

[0010] However, when a manganese compound is added as a modifying oxide, although the blackness and coloring power of the pigment increase with the increase in the addition amount, on the other hand, there is a tendency for its durability such as acid resistance or weather resistance to decrease. The valence of chromium ions in the spinel structure constituting the Cu-Cr-O composite oxide pigment is trivalent and stable, but when the durability of the pigment itself decreases, hexavalent chromium eluted from the pigment may affect the environment and health. For example, EU member states have restricted the use of specific hazardous substances contained in electrical and electronic equipment in their countries. If the elution amount of hexavalent chromium is greater than 1000 ppm, the product cannot be sold on the market.

[0011] The elution amount of hexavalent chromium from composite oxide pigments containing chromium varies greatly depending on the content, the type of coexisting solid solution substances, firing conditions, washing state, etc. For example, for C.I. Pigment Black 28, the elution amount of hexavalent chromium sometimes exceeds 1000 ppm.

[0012] In addition, glass pigments, which are listed as one of the uses of Cu-Cr-O composite oxide pigments, are mainly used for automotive window glass. The purpose is to give design to the boundary between the body with different hues and the window glass, and for the anti-ultraviolet of urethane adhesives used for the joint between the body and the glass, etc. It is required to have blackness, light-shielding property in the pigment, and acid resistance as the ability to prevent color change due to rainwater. Glass pigments are mixtures composed of inorganic components such as glass powder, inorganic pigments, and fillers and an organic carrier. After being coated on glass products by screen printing or the like, they are fired at a high temperature of 500 to 700 °C, whereby design can be given to the glass products.

[0013] However, when applying glass pigments on a float glass sheet and firing them, sometimes the copper in the Cu-Cr-O composite oxide pigment component is reduced by the tin on the glass sheet surface, causing the boundary between the tin surface of the glass sheet and the applied glass pigment to change color and turn red (red discoloration). Since this can damage the design of glass products, a Cu-Cr-O composite oxide pigment that does not cause red discoloration is sought. Red discoloration of glass pigments also occurs when the durability of the pigment is low, but there is a tendency for red discoloration to occur more significantly as the Mn content in the Cu-Cr-Mn-O composite oxide pigment increases. In addition, a Mn-free Cu-Cr-O composite oxide pigment produced by a dry process cannot exhibit sufficient blackness and light-shielding properties required for glass pigments.

[0014] Patent Document 1 discloses a technique in which a pigment is brought into contact with hydrous silica and a substance having reducing properties in a slurry of a composite oxide pigment containing chromium, and the pigment is treated with these substances to reduce the elution amount of hexavalent chromium. However, the manufacturing process of this technique is cumbersome and not suitable for general-purpose products.

[0015] Patent Document 2 describes a copper-chromium type black pigment obtained by adding 15% or less of oxides of iron, nickel, cobalt, manganese, molybdenum, tungsten, vanadium, or uranium to a mixture of copper oxide and chromium oxide, and then firing the resulting mixture at a temperature of 800 to 1100°C. However, a black pigment that does not contain a large amount of manganese in its composition cannot exhibit high blackness or coloring power.

[0016] Patent Document 3 describes a composite oxide pigment that can have sufficient blackness as a pigment for glass enamel (synonymous with the glass pigment in this application) and reduce the thermal expansion rate of glass (written as CTE: Coefficients of thermal expansion (thermal expansion coefficient) in this document) by making the Cu-Mn-Cr-O (not necessarily containing Mn) composite oxide contain at least one metal selected from the group consisting of Al, Mg, Ti, Fe, Co, Ni, Zn, Zr, Nb, Y, W, Sb, and Ca. However, the durability of the pigment is not described in Patent Document 3. In addition, as the applicant of this application will explain in the following detailed description, the composition disclosed in Patent Document 3 cannot guarantee sufficient high-temperature stability.

[0017] Prior art documents

[0018] Patent documents

[0019] Patent Document 1: Japanese Patent Laid-Open No. 8-27393

[0020] Patent Document 2: U.S. Patent No. 2309173 Specification

[0021] Patent Document 3: Specification of U.S. Patent No. 11,174,170 Summary of the Invention

[0022] Technical Problem to be Solved by the Invention

[0023] In view of the above background, an object of the present invention is to provide a Cu-Cr-O composite oxide pigment having excellent color characteristics and improved durability.

[0024] Technical Means for Solving the Technical Problem

[0025] The inventors of the present application found that when preparing a batch by a dry method in a Cu-Cr-O composite oxide pigment, instead of using a manganese compound or an iron compound known as a modifying oxide, zinc oxide that has not been used before is added within a limited composition range, and firing is performed at an appropriate temperature within a relatively high temperature range. As a result, both the color characteristics and the durability of the pigment can be significantly improved compared with conventional Cu-Cr-O composite oxide pigments, thus completing the present invention. That is, even without containing Mn or Fe, the present application can achieve both high blackness and high durability of the Cu-Cr-O composite oxide pigment by selecting Zn as a metal element that is solid-dissolved in the Cu-Cr-O composite oxide.

[0026] That is, the present invention relates to a Cu-Cr-Zn-O composite oxide pigment, which is a Cu-Cr-Zn-O composite oxide pigment in which Zn from zinc oxide added as a modifying oxide is solid-dissolved in the Cu-Cr-O composite oxide.

[0027] The Cu-Cr-Zn-O composite oxide pigment has an oxide composition formula: aCuO·bCr 2 O 3 ·cZnO (mol%), where 0.1 ≤ c ≤ 5, 45 ≤ a + c ≤ 55, 45 ≤ b ≤ 55 (a + b + c = 100).

[0028] Preferably, the X-ray diffraction pattern of the above Cu-Cr-Zn-O composite oxide pigment does not contain the by-product CuCrO 2 .

[0029] Preferably, the above Cu-Cr-Zn-O composite oxide pigment forms a spinel structure, and is characterized in that a batch prepared by dry mixing starting materials of a copper compound, a chromium compound, and a zinc compound is fired at a temperature of 800 to 1000°C.

[0030] Preferably, the above Cu-Cr-Zn-O composite oxide pigment is used as a coloring pigment for coatings, plastics, and glass.

[0031] Preferably, the amount of hexavalent chromium dissolved in the pigment solution of the above Cu-Cr-Zn-O composite oxide pigment measured by the EPA 3060A method is 250 ppm or less.

[0032] Preferably, the above Cu-Cr-Zn-O composite oxide pigment is used for glass pigments and does not turn red on the tin surface of the float glass sheet when fired at 500 to 700 °C.

[0033] Preferably, the above Cu-Cr-Zn-O composite oxide pigment is used in laser direct structuring (LDS).

[0034] Hereinafter, the content described in the specification of U.S. Patent No. 11,174,170 (hereinafter referred to as the cited document) is compared with the invention of the present application to further clarify the features of the invention of the present application. The applicant of the present application believes that the specification of U.S. Patent No. 11,174,170 is the invention closest to the invention of claim 1 of the present application among the patent gazettes published at the time of filing the present application.

[0035] Claim 1 of the cited document discloses a modified copper chromite black spinel,

[0036] which contains a copper chromite solid solution having the formula A a Cu b Mn c Cr d O 4 and

[0037] A is at least one metal selected from the group consisting of Al, Mg, Ti, Fe, Co, Ni, Zn, Zr, Nb, Y, W, Sb, and Ca,

[0038] 2.6 ≤ a + b + c + d ≤ 3.2,

[0039] a, b, and d are all non-zero.

[0040] Here, according to the above stipulation that "a, b, and d are all non-zero", it also includes the case where c representing the composition amount of Mn is zero.

[0041] In addition, "Zn" is included among the metals listed as A.

[0042] Therefore, it can be determined that the invention of the cited document 1 includes the invention of the present application in its composition.

[0043] However, from the following two aspects, the invention of the present application has a different technical meaning from the cited document 1.

[0044] 1. As described in paragraph

[0017] of Cited Document 1, the technical problem of Cited Document 1 is "to obtain a black pigment with a reduced CTE". To solve this technical problem, a secondary modifier is used which is "at least one metal selected from the group consisting of Al, Mg, Ti, Fe, Co, Ni, Zn, Zr, Nb, Y, W, Sb, and Ca".

[0045] In contrast, the technical problem of the invention of the present application is to improve color characteristics and durability. To solve this technical problem, Zn is used as a metal included in addition to the main components Cu and Cr.

[0046] The CTE in the cited document is completely irrelevant to the "color characteristics" and "durability" in the invention of the present application, and there is no description or suggestion that would motivate the selection of the unique combination of c = 0 and A = Zn from the invention of Cited Document 1 to achieve the excellent "color characteristics" and "durability" as described in the invention of the present application. That is, the invention of the present application has a unique technical significance different from the cited document.

[0047] 2. The Cu - Cr - Zn - O composite oxide pigment in the invention of the present application is formed by dissolving Zn from zinc oxide added as a modifying oxide in a Cu - Cr - O composite oxide having a spinel structure CuCr 2 O 4 .

[0048] Here, in this specification and the claims, "dissolving Zn from zinc oxide added as a modifying oxide in a Cu - Cr - O composite oxide having a spinel structure CuCr 2 O 4 " means "formed from a Cu - Cr - O composite oxide having a spinel structure CuCr 2 O 4 and Zn from zinc oxide", which not only includes the meaning of not containing other types of metals such as Mn and Fe that do not come from the above metal oxides, but also includes the meaning of not containing CuCrO 2 as a secondary phase.

[0049] As will be clarified in the examples described later, when ZnO is not used as a modifying oxide, that is, when no modifying oxide is used and when MnO 2 , Fe 2 O 3 is used as a modifying oxide, regardless of the firing conditions selected, the result will contain at least any one of Cr 2 O 3 and CuCrO 2 .

[0050] Therefore, "dissolving Zn from zinc oxide added as a modifying oxide into the Cu-Cr-O composite oxide having a spinel structure" is a unique feature of the invention of this application. 2 O 4 to form a Cu-Cr-O composite oxide" is a unique feature of the invention of this application.

[0051] Advantages of the Invention

[0052] The Cu-Cr-Zn-O composite oxide obtained by dissolving Zn from zinc oxide added as a modifying oxide into the Cu-Cr-O composite oxide in the present invention has excellent color characteristics as a pigment and can improve the durability of the Cu-Cr-O composite oxide pigment. Description of the Drawings

[0053] Figure 1a It is a diagram showing the XRD pattern of the pigment of Example 10.

[0054] Figure 1b It is a diagram showing the XRD pattern of the pigment of Comparative Example 2.

[0055] Figure 1c It is a diagram showing the XRD pattern of the pigment of Comparative Example 5.

[0056] Figure 1d It is a diagram showing the XRD pattern of the pigment of Comparative Example 8.

[0057] Figure 2 It is a photograph of the tin surface of a glass plate after a redness change test using various pigments. Detailed Description of the Invention

[0058] Hereinafter, embodiments of the present invention will be described in detail.

[0059] The Cu-Cr-Zn-O composite oxide pigment of the present invention is obtained by dissolving Zn from zinc oxide added as a modifying oxide into a Cu-Cr-O composite oxide having a spinel structure.

[0060] Furthermore, the Cu-Cr-Zn-O composite oxide pigment of the present invention has an oxide composition formula: aCuO·bCr 2 O 3 ·cZnO (mol%), where 0.1 ≤ c ≤ 5, 45 ≤ a + c ≤ 55, 45 ≤ b ≤ 55 (a + b + c = 100).

[0061] The spinel structure is a typical crystal structure form commonly found in composite oxides and composite sulfides with the general formula AB 2 X 4 of metal elements. The Cu-Cr-O composite oxide having a spinel structure has the general formula CuCr2 O 4 。

[0062] As described above, ZnO in the oxide composition of the Cu-Cr-Zn-O composite oxide pigment of the present invention is added as a modifying oxide.

[0063] Zinc oxide ZnO has not been used as a modifying oxide in the past. However, if this zinc oxide ZnO is added in an appropriate amount when blending raw materials in the pigment manufacturing process, and the batch obtained through a dry mixing process is fired within a specified temperature range, the reactivity during sintering will be improved, and thus the color characteristics and durability will be significantly improved compared to conventional Cu-Cr-O composite oxide pigments (i.e., Cu-Cr-O composite oxide pigments without added modifying oxides, or Cu-Cr-O composite oxide pigments added with other modifying oxides such as manganese oxide MnO 2 and iron oxide Fe 2 O 3 ).

[0064] Although the Cu-Cr-Zn-O composite oxide pigment of the present invention belongs to C.I. Pigment Black 28 in terms of pigment components, the Cu-Cr-Zn-O composite oxide pigment of the present invention is different from existing substances in that it contains neither Mn nor Fe as the metal of the modifying oxide. Based on this distinguishing technical feature, the Cu-Cr-Zn-O composite oxide pigment of the present invention has the following characteristics in terms of color characteristics: it has the advantage of having a blackness roughly equal to that of conventional Cu-Cr-Mn-O composite oxide pigments, but higher red and blue tones.

[0065] The oxide composition of the Cu-Cr-Zn-O composite oxide pigment of the present invention preferably consists of 40 - 54.9 mol% of copper oxide (CuO), 45 - 55 mol% of chromium oxide (Cr 2 O 3 ) and 0.1 - 5.0 mol% of zinc oxide (ZnO) as an additive component. It is known that when the oxide composition amount of the pigment is outside this range, sufficient color characteristics and durability cannot be obtained.

[0066] Specifically, by using ZnO as a modifying oxide, the color characteristics of the Cu-Cr-O composite oxide pigment can be significantly improved. Specifically, compared with the Cu-Cr-O composite oxide pigment, in the Cu-Cr-Zn-O composite oxide pigment in which the composition and firing temperature of the three components consisting of CuO, Cr 2 O 3 and ZnO have been optimized, when preparing an acrylic paint with a pigment concentration of 10 wt% and spreading it with a paint thickness of 150 μm, the L in the hue *Reduce by about 2.0 or more, a * Increase by about 0.5 or more, and b * Reduce by 0.5 or more.

[0067] It is known that in the conventional methods for improving color characteristics, MnO 2 or Fe 2 O 3 is used as a modifying oxide. However, compared with the Cu-Cr-Mn-O composite oxide pigment using MnO 2 as a modifying oxide, the a * of the Cu-Cr-Zn-O composite oxide pigment of the present invention using ZnO as a modifying oxide is high and b * is low. Or, compared with the Cu-Cr-Fe-O composite oxide pigment using Fe 2 O 3 as a modifying oxide, the L * of the Cu-Cr-Zn-O composite oxide pigment of the present invention using ZnO as a modifying oxide is low and b * is low. From this perspective, the Cu-Cr-Zn-O composite oxide pigment of the present invention using ZnO as a modifying oxide has more excellent color characteristics.

[0068] In addition, the durability of the pigment of the present invention has been greatly improved. That is, it has acid resistance and alkali resistance, and thus can prevent the dissolution of hexavalent chromium to the outside.

[0069] Furthermore, the pigment of the present invention can provide a glass pigment with suppressed red discoloration for use as a glass pigment.

[0070] Although this effect can be obtained by firing in a relatively high temperature range of 800 to 1000 °C, at the time of filing the present invention, it was not clear which structure or property in this pigment brought about this effect. Therefore, the scope of the present invention had to be defined by the above temperature range.

[0071] Next, a method for manufacturing the Cu-Cr-Zn-O composite oxide pigment of the present invention will be described.

[0072] The pigment of the present invention has a Cu-Cr-O composite oxide as the main component, and further contains Zn from zinc oxide added as a modifying oxide therein. Therefore, a copper compound, a chromium compound, and a zinc compound are separately prepared as the above raw materials.

[0073] As long as each raw material contains the above metal elements and becomes its respective oxide during the manufacturing process, it can be any substance. As their compounds, specifically, hydroxides, oxides, carbonates, etc. can be cited, and each of them can be a single substance or a combination of multiple substances.

[0074] Any manufacturing method may be used as long as it is a known method for manufacturing a composite oxide pigment mainly composed of a metal oxide. Such a manufacturing method mainly consists of a mixing process 1) of raw materials, a firing process 2) of the resulting mixture, and a pulverizing process 3) of the fired product.

[0075] The mixing process 1) of raw materials is limited to the dry method. This is because if other methods are used, there are problems such as complication of the manufacturing method or process, increase in production cost, and the need for wastewater treatment equipment.

[0076] In the firing process 2) of the resulting mixture, the resulting mixture (batch) is fired at 800°C to 1000°C for about 3 to 6 hours to cause solid solution and crystallization of each component.

[0077] It is known that if the firing temperature is too high, the color characteristics will be reduced due to the formation of a secondary phase, and if the firing temperature is too low, insufficient color development or uneven firing will occur.

[0078] In the present invention, by firing within the above temperature range of 800°C to 1000°C, an effect of reducing L * , increasing a * , and reducing b * is obtained. In contrast, in conventional composite oxide pigments using MnO 2 or Fe 2 O 3 as a modifying oxide, if fired at a temperature of 900°C or higher, a secondary phase CuCrO 2 will be generated, and as a result, a problem of increasing L * will occur.

[0079] Finally, the fired product obtained through process 2) is subjected to the pulverizing process 3). This pulverizing process 3) usually adjusts the particle size by pulverization. As long as a pigment with the desired particle size can be obtained, the pulverization method is not particularly limited, and ordinary dry pulverization or wet pulverization can be applied.

[0080] As an example of a pulverizer, an attritor or a jetmill can be cited for dry pulverization, and a ball mill, a vibration mill, or a media agitation mill can be cited for wet pulverization. In wet pulverization, the pulverized slurry is sufficiently dried and then crushed to obtain the target product.

[0081] According to the above manufacturing method, when preparing a batch for a Cu-Cr-O composite oxide pigment having a spinel structure composed of Cu and Cr by a dry process, a specified amount of zinc oxide is added as a modifying oxide, whereby the color characteristics of the Cu-Cr-O composite oxide pigment can be significantly improved.

[0082] In addition, although it is known to use MnO 2 or Fe 2 O 3 as a modifying oxide in the method of improving color characteristics, compared with using these modifying oxides, when ZnO is used as a modifying oxide, it has more excellent color characteristics and can also significantly improve the durability of the pigment.

[0083] Furthermore, the manufacturing process of the pigment of the present invention is also simple and can be used as a general-purpose product.

[0084] Examples

[0085] To specifically illustrate the present invention, several examples of the present invention and comparative examples for comparison therewith are listed below.

[0086] For convenience, the pigment composition is expressed as aCuO·bCr 2 O 3 ·cX (mol%) (X = ZnO, Mn 2 O 3 , Fe 2 O 3 ).

[0087] (Examples 1 to 21)

[0088] In the following Examples 1 to 21, based on the compositional formula aCuO·bCr 2 O 3 ·cZnO (mol%), (a, b, c) were variously changed within the range of satisfying 0.1 ≤ c ≤ 10, 40 ≤ a + b ≤ 60, and 40 ≤ b ≤ 60 (a + b + c = 100) to form a target pigment composition and a specified amount of copper oxide, chromium oxide, and zinc oxide were weighed so that the total weight reached 100 g. The specific values of (a, b, c) are shown in Table 1 below.

[0089] Next, they were thoroughly mixed using a ball mill until a homogeneous mixture (batch) was obtained.

[0090] Next, 30 g of this batch was weighed and added to a mullite crucible, and firing was performed using an electric furnace. As the firing conditions, each composition was fired at 800 °C, 900 °C, and 1000 °C for 9 hours.

[0091] After firing the batch material, 25 g of the obtained fired product, 100 g of glass beads with a diameter φ of 3 mm, and 50 g of distilled water were weighed separately and added to a glass container with a capacity of 140 mL. The container was covered, and the fired product was pulverized for 30 minutes using a paint conditioner.

[0092] After pulverizing the fired product, the pulverized slurry was poured into an aluminum foil container and dried at 120 °C for about 5 hours.

[0093] After the pulverized slurry was dried, the dried product was crushed using a pestle and mortar to produce a pigment with the target composition.

[0094] (Comparative Examples 1 - 3)

[0095] Different from Examples 1 - 21, based on aCuO·bCr 2 O 3 (mol%), within the range of 45 ≤ a ≤ 55 and 45 ≤ b ≤ 55 (a + b = 100), (a, b) was selected to produce a Cu - Cr - O composite oxide pigment composed of Cu and Cr without a modifying oxide.

[0096] The production method was set to the same operation as in Examples 1 - 21 above.

[0097] (Comparative Examples 4 - 6)

[0098] Based on aCuO·bCr 2 O 3 ·cMn 2 O 3 (mol%), within the range of 45 ≤ a ≤ 55, 40 ≤ b ≤ 50, and c = 5 (a + b + c = 100), (a, b, c) was set to produce a Cu - Cr - Mn - O composite oxide pigment composed of Cu, Cr, and Mn containing the metal element Mn from manganese dioxide MnO 2 which was added as a modifying oxide in the past.

[0099] The production method of the pigment was set to the same operation as in Examples 1 - 21 above.

[0100] (Comparative Examples 7 - 9)

[0101] Based on aCuO·bCr 2 O 3 ·cFe 2 O 3 (mol%), within the range of 45 ≤ a ≤ 55, 40 ≤ b ≤ 50, and c = 5 (a + b + c = 100), (a, b, c) was selected, and through the same operation as in Examples 1 - 21 above, a pigment containing iron oxide Fe2 O 3 The Cu-Cr-Fe-O composite oxide pigment composed of Cu, Cr and Fe of the metal element Fe of

[0102] (Characteristic evaluation)

[0103] ((a) Hue)

[0104] Using a paint mixer, 10 parts by weight each of the composite oxide pigments obtained in Examples 1 to 21 and Comparative Examples 1 to 9 were dispersed in 100 parts by weight of an acrylic resin.

[0105] Next, the obtained paint was spread on white paper using a 150 μm coater. After drying, the color of the coating film was measured using a spectrophotometer (standard light source C, 2° viewing angle).

[0106] For the purpose of evaluating this result, the color measurement results in the CIELAB color system are shown in Table 1 below.

[0107] ((b) XRD diffraction pattern analysis)

[0108] From the Cu-Cr-Zn-O, Cu-Cr-O, Cu-Cr-Mn-O or Cu-Cr-Fe-O composite oxide pigments respectively prepared in Examples 1 to 21 and Comparative Examples 1 to 9, the compositions with the most excellent color characteristics were selected respectively. For each component system, the XRD diffraction patterns of the pigments prepared at firing temperatures of 800 °C, 900 °C and 1000 °C were compared, and thus the change of the crystal structure of the pigments with the increase of the firing temperature during the production of the pigments was observed.

[0109] ((c) Acid and alkali resistance test)

[0110] According to the evaluation results of (a) and (b), the compositions with the most excellent color characteristics and no heterogeneous phase CuCrO detected in the crystal structure were respectively selected from the prepared Cu-Cr-Zn-O, Cu-Cr, Cu-Cr-Mn-O or Cu-Cr-Fe-O composite oxide pigments. 2 Specifically, the Cu-Cr-Zn-O composite oxide pigment fired at 1000 °C in Example 10, the Cu-Cr-O composite oxide pigment fired at 800 °C in Comparative Example 2, the Cu-Cr-Mn-O composite oxide pigment fired at 800 °C in Comparative Example 5 and the Cu-Cr-Fe-O composite oxide pigment fired at 800 °C in Comparative Example 8 were selected.

[0111] The selected pigments were weighed respectively so that the pigment concentration was 10 wt%, and added to 5 wt% HCl aqueous solution or 20 wt% NaOH aqueous solution, and immersed for 3 days.

[0112] After the pigment was immersed for 3 days, the leachate was extracted by suction filtration.

[0113] The main component amounts of the pigments respectively immersed in the leachate were measured by ICP (Inductively Coupled Plasma) chemical analysis, and thereby the durability of the pigments in each component system was compared.

[0114] ((d) Evaluation of hexavalent chromium dissolution amount)

[0115] Using the method based on EPA3060A (Alkaline Digestion for Hexavalent Chromium), leachates of hexavalent chromium were prepared from the Cu-Cr-Zn-O composite oxide pigment fired at 1000 °C in Example 10, the Cu-Cr-O composite oxide pigment fired at 800 °C in Comparative Example 2, the Cu-Cr-Mn-O composite oxide pigment fired at 800 °C in Comparative Example 5, and the Cu-Cr-Fe-O composite oxide pigment fired at 800 °C in Comparative Example 8. The hexavalent chromium concentration in the leachate was measured by the diphenylcarbazide spectrophotometric method (JIS K0102).

[0116] ((e) Evaluation of red shift of glass pigment)

[0117] For the Cu-Cr-Zn-O composite oxide pigment fired at 1000 °C in Example 10, the Cu-Cr-O composite oxide pigment fired at 800 °C in Comparative Example 2, the Cu-Cr-Mn-O composite oxide pigment fired at 800 °C in Comparative Example 5, and the Cu-Cr-Fe-O composite oxide pigment fired at 800 °C in Comparative Example 8, 1.2 g of the pigment and 0.6 g of the carrier were weighed, and thoroughly mixed using a Hoover Muller dispersive property grinder to prepare a paste. Using a coater with a thickness of 76.2 μm, the prepared paste was spread on the tin surface of a glass plate and dried in a drying oven at 120 °C for 30 minutes. Further, the glass plate was fired in an electric furnace at 680 °C for 20 minutes, allowed to cool naturally sufficiently, and the pigment on the glass plate was rinsed with tap water, and the degree of occurrence of red shift on the tin surface of the glass plate was observed.

[0118] Next, the results of the above respective tests will be described.

[0119] For Examples 1 to 20 and Comparative Examples 1 to 9, the hues at each firing temperature set when preparing the Cu-Cr-Zn-O, Cu-Cr-O, Cu-Cr-Mn-O or Cu-Cr-Fe-O composite oxide pigments are shown in Table 1 below.

[0120] [Table 1a]

[0121]

[0122] [Table 1b]

[0123]

[0124] [Table 1c]

[0125]

[0126] In the above table, L * represents lightness, +a * represents the hue in the red direction, -a * represents the hue in the green direction, +b * represents the hue in the yellow direction, -b * represents the hue in the blue direction. In addition, regarding the black pigment, a hue with high blackness, strong red, and strong blue is preferred. Based on comparing the significant differences in hue characteristics, it is comprehensively observed and judged that L * is low, and a * is high, and b * is low.

[0127] In addition, Figure 1a shows the XRD patterns of the firing temperatures of 800 °C, 900 °C, and 1000 °C in Example 10, Figure 1b shows the XRD patterns of the firing temperatures of 800 °C, 900 °C, and 1000 °C in Comparative Example 2.

[0128] According to Table 1 above, for the Cu-Cr-O composite oxide pigment without added modifier oxide, according to Comparative Examples 1 to 3, the L of the pigment produced at a firing temperature of 800 °C * is 11.7 to 11.8, the L of the pigment produced at a firing temperature of 900 °C * is 12.0 to 15.3, and further the L of the pigment produced at a firing temperature of 1000 °C * is 12.0 to 16.2. In all comparative examples, a tendency for the blackness to decrease as the firing temperature increases was observed.

[0129] In addition, according to Figure 1b the XRD pattern of the Cu-Cr-O composite oxide pigment shown in Comparative Example 2 at a firing temperature of 800 °C, in addition to the diffraction peaks attributed to the main phase CuCr 2 O 4 diffraction peaks, diffraction peaks attributed to the raw material Cr 2 O 3 were also detected. On the other hand, in the pigments produced at firing temperatures of 900 °C or higher, in addition to the main phase CuCr2 O 4 and Cr 2 O 3 In addition to this, diffraction peaks attributed to the secondary phase CuCrO 2 were further detected.

[0130] From this, it can be seen that when producing a Cu-Cr-O composite oxide pigment composed of Cu and Cr, even if the composition design is carried out in such a way that the starting copper oxide and chromium oxide react theoretically in a proper manner, for the batch obtained by the dry method, the reaction between the raw materials during firing is insufficient. Further, it also implies that when producing a Cu-Cr-O composite oxide pigment, it is necessary to set an optimal firing temperature. If firing is carried out at a temperature above this temperature, in addition to the main phase CuCr 2 O 4 in addition, a secondary phase CuCrO 2 will be formed in the pigment, and as a result, the blackness of the pigment will decrease.

[0131] Therefore, it can be known that the optimal firing temperature when producing a Cu-Cr-O composite oxide pigment from the batch obtained by the dry method is preferably around 800 °C. Conversely, firing should not be carried out at a high temperature above 900 °C.

[0132] For the Cu-Cr-Mn-O composite oxide pigment with MnO 2 added as a modifying oxide, according to Comparative Examples 4 to 6, the L * of the pigment produced at a firing temperature of 800 °C is 9.5 to 11.7, and compared with the Cu-Cr-O composite oxide pigment shown in Comparative Examples 1 to 3, it has a higher blackness and more excellent color characteristics. On the other hand, compared with the pigment produced at a firing temperature of 800 °C, the L * of the pigment produced at a firing temperature above 900 °C decreases. Similar to the Cu-Cr-O composite oxide pigment, a tendency for the blackness to decrease with an increase in the firing temperature was also observed for the Cu-Cr-Mn-O composite oxide pigment.

[0133] According to Figure 1c the XRD pattern of the Cu-Cr-Mn-O composite oxide pigment shown in Comparative Example 5, similar to Comparative Example 2, in the pigment produced at a firing temperature above 900 °C, in addition to the main phase CuCr 2 O 4 in addition, diffraction peaks attributed to the secondary phase CuCrO 2 were also detected. Therefore, it can be known that when adding MnO 2When producing Cu-Cr-Mn-O composite oxide pigments using a modifying oxide, the color characteristics of the pigments are significantly improved. However, the firing temperature during pigment production is preferably around 800 °C, similar to that of Cu-Cr-O composite oxide pigments. Conversely, firing should not be carried out at a high temperature above 900 °C.

[0134] Regarding the addition of Fe 2 O 3 For the Cu-Cr-Fe-O composite oxide pigments with FeO as the modifying oxide, according to Comparative Examples 7 - 9, it can be seen from the results in Table 1 that for the pigments produced at a firing temperature of 800 °C, the L * is 10.8 - 11.2. Compared with the Cu-Cr-O composite oxide pigments shown in Comparative Examples 1 - 3, the blackness is higher and an improvement in color characteristics is observed. However, no improvement is observed as in the case of the Cu-Cr-Mn-O composite oxide pigments with MnO added as shown in Comparative Examples 4 - 6. 2 as the modifying oxide.

[0135] In addition, according to Figure 1d the XRD patterns of the Cu-Cr-Fe-O composite oxide pigments shown in Comparative Example 8, there is the same tendency as the XRD patterns of the Cu-Cr-O composite oxide pigments shown in Comparative Example 2 and the Cu-Cr-Mn-O composite oxide pigments shown in Comparative Example 5. Therefore, it can be known that when producing Cu-Cr-Fe-O composite oxide pigments using FeO 2 O 3 as the modifying oxide, the color characteristics of the pigments are slightly improved. The firing temperature during pigment production is preferably around 800 °C, similar to that of Cu-Cr-O composite oxide pigments and Cu-Cr-Mn-O composite oxide pigments. Conversely, firing should not be carried out at a high temperature above 900 °C.

[0136] Regarding the pigments of Examples 1 - 21 with ZnO added as the modifying oxide

[0137] aCuO·bCr 2 O 3 ·cZnO (mol%), if (a, b, c) are selected within the range satisfying 0.1 ≤ c ≤ 5, 45 ≤ a + c ≤ 55, 45 ≤

[0138] b ≤ 55 (a + b + c = 100) in Examples 5 - 7, Examples 9 - 12, and Examples 14 - 16, and the Cu-Cr-Zn-O composite oxide pigments produced under the firing temperature conditions with the highest blackness are selected from each composition, then the L *is 9.3 to 11.5. Compared with the Cu-Cr-O composite oxide pigments shown in Comparative Examples 1 to 3, an improvement in blackness as a pigment property was observed, and a color property better than that of the case where MnO was added was confirmed therein. 2 The Cu-Cr-Mn-O composite oxide pigments shown in Comparative Examples 4 to 6 as modified oxides are excellent (a * is high and b * is low, that is, the red color is strong and the blue color is strong).

[0139] Furthermore, in the Cu-Cr-Zn-O composite oxide pigment, a composition in which the color property of the pigment increases as the firing temperature during pigment production is set to increase in the range of 800 °C to 1000 °C was also confirmed.

[0140] According to Figure 1a the XRD pattern of the Cu-Cr-Zn-O composite oxide pigment shown in Example 10, only the diffraction peaks attributed to the main phase CuCr 2 O 4 were detected in the pigments produced at firing temperatures of 800 °C, 900 °C, and 1000 °C. When comparing the XRD patterns of the pigments of the Cu-Cr-O composite oxide pigments shown in Example 10 and Comparative Example 2 produced at a firing temperature of 800 °C, the intensity of the diffraction peak attributed to the raw material Cr 2 O 3 used was small in Example 10, and almost no diffraction peak attributed to Cr 2 O 3 was detected in the pigment produced at a firing temperature of 1000 °C in Example 10. From this, it can be considered that by adding ZnO as a modified oxide, the reactivity between different types of raw materials during firing was also sufficiently improved.

[0141] Furthermore, according to the XRD patterns of Comparative Example 2, Comparative Example 5, and Comparative Example 8, in the Cu-Cr-O, Cu-Cr-Mn-O, and Cu-Cr-Fe-O composite oxides, diffraction peaks attributed to the secondary phase CuCrO 2 were all detected in each pigment produced at a firing temperature of 900 °C or higher, but in the Cu-Cr-Zn-O composite oxide shown in Example 10, no diffraction peak attributed to the secondary phase CuCrO 2 was detected even in the pigment produced at a firing temperature of 1000 °C. Therefore, it is known that when ZnO is added as a modified oxide, the firing temperature during pigment production can be set higher than in the case of adding known MnO 2 or Fe 2 O 3 as a modified oxide.

[0142] Next, the results of the (c) acid and alkali resistance tests will be described.

[0143] The results of the acid resistance test are shown in Table 2 below, and the results of the alkali resistance test are shown in Table 3 below.

[0144] [Table 2]

[0145]

[0146] [Table 3]

[0147]

[0148] Based on the results shown in Tables 2 and 3 above, in terms of the durability of the pigment, the Cu-Cr-Zn-O composite oxide pigment of the present invention has obtained better results in acid and alkali resistance than other pigments.

[0149] Depending on the intended use, a pigment is required to have acid resistance or alkali resistance. For example, when used in acid-resistant coatings, acid-resistant rubbers, or vinyl chloride resins, etc., a pigment with good acid resistance needs to be used. When used in coatings for concrete or mortar, coatings with an alkaline substance such as sodium silicate as a carrier, etc., a pigment with good alkali resistance needs to be used. When the acid and alkali resistance of a pigment is poor, the pigment will have poor dispersion in the solvent for coloring purposes, and due to decomposition, there will be elution of pigment components or a change in hue over time. The Cu-Cr-O composite oxide pigment may have elution of hexavalent chromium in the solvent, but compared with Cu-Cr-O, Cu-Cr-Mn-O, or Cu-Cr-Fe-O composite oxide pigments, the Cu-Cr-Zn-O composite oxide pigment of the present invention has the most excellent durability of the pigment itself.

[0150] In addition, for example, in terms of acid resistance or alkali resistance, the smaller the solid-liquid boundary of the pigment relative to the resin or coating, the fewer eluted ions. Therefore, it is considered that in addition to the stability of the crystal structure, the durability of the pigment also results from the size of the pigment particle diameter. In the solid-phase reaction in the firing process when producing a composite oxide pigment, the higher the firing temperature, the more grain growth is promoted and the coarser the grains become. As a result, for the reason that it is easy to control the size of the obtained pigment particle diameter, compared with Cu-Cr-O, Cu-Cr-Mn-O, or Cu-Cr-Fe-O composite oxide pigments, the Cu-Cr-Zn-O composite oxide pigment that can be set at a higher firing temperature has higher durability of the pigment itself.

[0151] Next, the evaluation results of the (d) hexavalent chromium elution amount will be described. This evaluation is based on the EPA3060A method.

[0152] The evaluation results of the hexavalent chromium elution amount measured based on the EPA3060A method are shown in Table 4 below.

[0153] [Table 4]

[0154]

[0155] According to Table 4 above, the pigment with the least hexavalent chromium elution amount is the Cu-Cr-Zn-O composite oxide pigment shown in Example 10, and its value is 250 ppm. In addition, compared with Example 10, the hexavalent chromium elution amounts of the Cu-Cr-O composite oxide pigment shown in Comparative Example 2, the Cu-Cr-Mn-O composite oxide pigment shown in Comparative Example 5, and the Cu-Cr-Fe-O composite oxide pigment shown in Comparative Example 8 are all more. Further, in Comparative Example 5, the hexavalent chromium elution amount is the largest, and its value is 681 ppm. According to the evaluation results of (a) and (d), in order to improve the hue of the Cu-Cr-O composite oxide pigment, adding MnO 2 as a method of modifying the oxide is very effective, but there is a disadvantage that the durability of the pigment is damaged due to the increase in the hexavalent chromium elution amount. On the other hand, since the Cu-Cr-Zn-O composite oxide pigment of the present invention adding ZnO as a modifying oxide takes into account both the improvement of the hue and the improvement of the durability of the Cu-Cr-O composite oxide pigment, it can be said that it is better than adding the known modifying oxide MnO 2 or Fe 2 O 3 of the Cu-Cr-O composite oxide pigment has an advantage.

[0156] Finally, the evaluation results of the red shift test of the (e) glass pigment will be described.

[0157] The photos of the tin side of the glass plate after the red shift test using various pigments are shown in Figure 2 .

[0158] According to the above, when the red shift test is carried out using the Cu-Cr-Zn-O composite oxide pigment shown in Example 10, the glass substrate hardly changes color, but in all cases where the red shift test is carried out using the Cu-Cr-O composite oxide pigment shown in Comparative Example 2, the Cu-Cr-Mn-O composite oxide pigment shown in Comparative Example 5, and the Cu-Cr-Fe-O composite oxide pigment shown in Comparative Example 8, the glass substrate changes color and turns red. The reason for the red shift of the glass pigment is that the copper in the Cu-Cr-O composite oxide pigment component is reduced by the tin on the surface of the glass plate. Generally, the lower the durability (heat resistance) of the Cu-Cr-O composite oxide pigment, the more significantly the red shift of the glass pigment will occur. Therefore, according to the evaluation results of the red shift test, compared with the Cu-Cr-O, Cu-Cr-Mn-O or Cu-Cr-Fe-O composite oxide pigment, the durability of the Cu-Cr-Zn-O composite oxide pigment of the present invention is excellent.

[0159] According to the characteristic tests of (a) to (e) above, compared with other Cu-Cr-O composite oxide pigments such as the commonly used Cu-Cr-Mn-O composite oxide pigment, the Cu-Cr-Zn-O composite oxide pigment of the present invention has the advantages of substantially the same blackness but higher red and blue tones in terms of color characteristics, and obviously more excellent effects in terms of the durability of the pigment.

Claims

1. A Cu-Cr-Zn-O composite oxide pigment, which is a Cu-Cr-Zn-O composite oxide pigment obtained by dissolving Zn from zinc oxide added as a modifying oxide in a Cu-Cr-O composite oxide. The Cu-Cr-Zn-O composite oxide pigment has an oxide composition formula: aCuO·bCr 2 O 3 ·cZnO (mol%), where 0.1 ≤ c ≤ 5, 45 ≤ a + c ≤ 55, 45 ≤ b ≤ 55 (a + b + c = 100).

2. The Cu-Cr-Zn-O composite oxide pigment according to claim 1, characterized in that, The X-ray diffraction pattern does not contain the by-product CuCrO 2 .

3. The Cu-Cr-Zn-O composite oxide pigment according to claim 1, which has a spinel structure formed. characterized in that, A batch material prepared by dry mixing starting materials of a copper compound, a chromium compound and a zinc compound is fired at a temperature of 800 to 1000 °C.

4. The Cu-Cr-Zn-O composite oxide pigment according to claim 1, which is used as a coloring pigment for coatings, plastics and glass.

5. The Cu-Cr-Zn-O composite oxide pigment according to claim 1, wherein, The amount of hexavalent chromium dissolved in the pigment solution measured based on the EPA3060A method is 250 ppm or less.

6. The Cu-Cr-Zn-O composite oxide pigment according to claim 1, wherein, When the Cu-Cr-Zn-O composite oxide pigment is used as a glass pigment and fired at 500 to 700 °C, no red discoloration occurs on the tin surface of the float glass sheet.

7. The Cu-Cr-Zn-O composite oxide pigment according to claim 1, which is used in laser direct structuring (LDS).

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