JPH06212445A - Production of chromated galvanized steel sheet - Google Patents

Production of chromated galvanized steel sheet

Info

Publication number
JPH06212445A
JPH06212445A JP23832593A JP23832593A JPH06212445A JP H06212445 A JPH06212445 A JP H06212445A JP 23832593 A JP23832593 A JP 23832593A JP 23832593 A JP23832593 A JP 23832593A JP H06212445 A JPH06212445 A JP H06212445A
Authority
JP
Japan
Prior art keywords
chromic acid
steel sheet
terms
treatment liquid
reduction product
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
JP23832593A
Other languages
Japanese (ja)
Other versions
JP3286959B2 (en
Inventor
Takafumi Yamaji
隆文 山地
Yasuhisa Tajiri
泰久 田尻
Takaaki Kondo
隆明 近藤
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
JFE Engineering Corp
Original Assignee
NKK Corp
Nippon Kokan Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by NKK Corp, Nippon Kokan Ltd filed Critical NKK Corp
Priority to JP23832593A priority Critical patent/JP3286959B2/en
Publication of JPH06212445A publication Critical patent/JPH06212445A/en
Application granted granted Critical
Publication of JP3286959B2 publication Critical patent/JP3286959B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
    • C23C22/24—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing hexavalent chromium compounds
    • C23C22/30—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing hexavalent chromium compounds containing also trivalent chromium

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  • Chemical & Material Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemical Treatment Of Metals (AREA)

Abstract

PURPOSE:To more stably and easily produce a chromated galvanized steel sheet excellent in appearance uniformity, sparing solubility, black rust resistance, aging film stability, coating property and corrosion resistance as compared with the conventional technique. CONSTITUTION:A chromating soln. consisting essentially of chromic acid, the reduction product of chromic acid and a colloidal soln. having >=10mmu average grain diameter and in which the weight ratio of the mixed chromic acid to reduction product of chromic acid is controlled to 1:0.3 to 0.55, expressed in terms of CrO3, the weight ratio of the total of the chromic acid and its reduction product, expressed in terms of CrO3, to the silica, expressed in terms of SiO2, is controlled to 1:1.5 to 2.5, the chromic acid concn. as Cr<6+> is adjusted to >=4g/l, and the silica concn., expressed in terms of SiO2, is controlled to >=20g/l is applied on the surface of a galvanized steel sheet, induction-heated and dried.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】この発明は、外観均一性、耐黒点
錆性、皮膜経時安定性、塗布性、耐食性に優れた難溶性
のクロメート処理亜鉛めっき鋼板の製造方法に関するも
のである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a sparingly soluble chromate-treated galvanized steel sheet having excellent appearance uniformity, black spot rust resistance, film stability over time, coating properties, and corrosion resistance.

【０００２】[0002]

【従来の技術】近年、クロメート処理鋼板の耐食性が向
上したことにより、電気メーカーなどにおいては、最終
製品にクロメート処理鋼板を無塗装で使用することが多
くなっている。その結果、鋼板の表面に外観、耐食性、
耐指紋性、塗装性等を付与させることが必要になり、こ
れらの性能を満足させるクロメート処理方法として、鋼
板表面にクロメート処理液を塗布し、水洗することなく
乾燥させることによりクロメート皮膜を形成する方法が
ある。2. Description of the Related Art In recent years, due to the improved corrosion resistance of chromate-treated steel sheets, electric manufacturers often use chromate-treated steel sheets for their final products without coating. As a result, the appearance, corrosion resistance, and
It is necessary to impart fingerprint resistance, paintability, etc., and as a chromate treatment method that satisfies these performances, a chromate film is formed by applying a chromate treatment liquid to the steel plate surface and drying without washing with water. There is a way.

【０００３】上述した性能を付与する具体例として、特
公昭42−14050、特公昭61−58552、特開昭61−284581、
特開昭63−218279、特開昭63−307281、特開昭64−6527
2、特開平1−283382、特公平３−66391、特公平３−681
15、特公平４−20992、特公平4−27297等の各特許公報
に開示された方法がある。これらはクロム酸化合物とシ
リカあるいはリン酸で構成されたクロメート皮膜を形成
するものであり、この皮膜は耐食性、塗装性、耐指紋
性、外観、処理液安定性等に優れている。As specific examples for imparting the above-mentioned performance, Japanese Patent Publication No. 42-14050, Japanese Patent Publication No. 61-58552, Japanese Patent Publication No. 61-284581,
JP-A-63-218279, JP-A-63-307281, JP-A-64-6527
2, JP-A-1-283382, JP-B-3-66391, JP-B-3-681
15, Japanese Patent Publication No. 4-20992, Japanese Patent Publication No. 4-27297, and the like. These form a chromate film composed of a chromic acid compound and silica or phosphoric acid, and this film is excellent in corrosion resistance, paintability, fingerprint resistance, appearance, treatment liquid stability and the like.

【０００４】上記各方法のうち、特公昭42−14050号公
報の方法はクロム酸1〜20ｇ／ｌ、けい酸ゾル１〜50ｇ
／ｌ及び３価クロムイオンを含む浴を用いるものであ
り、これによって耐食性を向上させることができたが、
塗装性、皮膜の非溶解性等が劣っていた。それらの欠点
は特公昭61−58552、特開昭61−284581、特開昭63−218
279、特開平１−283382、特公平３−66391、特公平３−
68115、特公平４−20992、特公平4−27297においてはク
ロム酸還元生成物の比率を高くすることにより既に解決
している。但し、これらは全て、処理液の改良により対
応を行ったものであり、改良した結果として低下する特
性はあるが処理液安定性及び耐黒点錆性が劣るという問
題は残る。Among the above methods, the method disclosed in Japanese Examined Patent Publication (Kokoku) No. 42-14050 is chromic acid 1 to 20 g / l, silicic acid sol 1 to 50 g.
/ L and a bath containing trivalent chromium ions were used, which was able to improve the corrosion resistance,
The paintability and film insolubility were poor. Those drawbacks are as follows: JP-B-61-58552, JP-A-61-284581 and JP-A-63-218.
279, JP-A-1-283382, JP-B 3-66391, JP-B 3-
68115, Japanese Patent Publication No. 4-20992, and Japanese Patent Publication No. 4-27297 have already solved the problem by increasing the ratio of the chromic acid reduction product. However, all of these have been dealt with by improving the treatment liquid, and although there is a characteristic that the treatment liquid decreases as a result of the improvement, there remains a problem that the treatment liquid stability and the black spot rust resistance are poor.

【０００５】[0005]

【発明が解決しようとする課題】ところで、電気亜鉛め
っき鋼板を素地に用いた場合に白錆発生には至らないも
のの黒点状の錆が発生し外観が損なわれることがあり、
長期の使用において外観品質を維持できないという問題
がある。また、クロメート処理を行った後、長期間保管
していると耐食性が低下するという問題がある。これら
の問題を解決できる手段としては、特公平3−68115に示
された如く処理液中にリン酸を相当量添加する方法、あ
るいは特開平1−283382の如くクロメート皮膜の乾燥板
温を200℃以上にする方法に効果を認められた。By the way, when an electrogalvanized steel sheet is used as a substrate, black rust may occur but the appearance may be impaired, although white rust may not occur.
There is a problem that the appearance quality cannot be maintained during long-term use. Further, there is a problem that the corrosion resistance is deteriorated if it is stored for a long time after the chromate treatment. As means for solving these problems, a method of adding a considerable amount of phosphoric acid to the treatment solution as shown in Japanese Patent Publication No. 3-68115, or a drying plate temperature of the chromate film as 200 ° C. as in JP-A-1-283382. The effect was recognized in the above method.

【０００６】しかし、リン酸を相当量添加する方法によ
ればクロメート皮膜の黄色度が低下し、黄色系の皮膜を
好むユーザーニーズを満足できない。また、リン酸の添
加量を増やすと共に高温高湿環境に鋼板が保管されると
表面が黒変化しやすくなり外観品質を維持できなくな
る。リン酸を少なくした場合には、逆に黄色度が強くな
り過ぎてわずかな塗布ムラも非常に目立ちやすいものし
か製造できない状態であった。したがって、リン酸量の
調整だけでは、全てを満足する皮膜を容易に製造するこ
とが困難であった。一方、乾燥板温を200℃以上にする
方法においては、黄色系の皮膜を形成できるが乾燥板温
が高いために焼き付け炉、冷却帯が必要であり生産性を
高める目的でライン速度を速くするにしたがってそれら
設備を大型化せざる得なくなり、結果的にコスト高とな
る。However, the method of adding a considerable amount of phosphoric acid lowers the yellowness of the chromate film, and cannot satisfy the needs of users who prefer a yellowish film. Further, when the amount of phosphoric acid added is increased and the steel sheet is stored in a high temperature and high humidity environment, the surface of the steel sheet is likely to turn black and the appearance quality cannot be maintained. On the contrary, when the amount of phosphoric acid was reduced, the yellowness became too strong, and only slight coating unevenness was very noticeable. Therefore, it was difficult to easily produce a film satisfying all of the requirements by only adjusting the amount of phosphoric acid. On the other hand, when the drying plate temperature is set to 200 ° C or higher, a yellowish film can be formed, but since the drying plate temperature is high, a baking furnace and a cooling zone are required, and the line speed is increased for the purpose of improving productivity. As a result, those facilities have to be increased in size, resulting in higher costs.

【０００７】本発明は上記の問題点を解決するべくなさ
れたものであり、外観均一性、難溶性、耐黒点錆性、皮
膜経時安定性、塗布性、耐食性、全てにおいて従来技術
より優れたクロメート処理亜鉛めっき鋼板をより安定的
かつ容易に製造する方法を提供することを目的とする。The present invention has been made to solve the above problems, and is superior to the prior art in terms of appearance uniformity, poor solubility, black spot rust resistance, film aging stability, coatability, and corrosion resistance. An object of the present invention is to provide a method for producing a treated galvanized steel sheet more stably and easily.

【０００８】[0008]

【課題を解決するための手段及び作用】この発明は、亜
鉛めっき鋼板の表面に、クロム酸(Ｃr6+）、クロム酸還
元生成物、及び平均粒子径10ｍμ以下のコロイダルシリ
カを主成分とし、クロム酸とクロム酸還元生成物との混
合比が各々ＣrＯ3換算での重量比で1：0.3〜0.55、クロ
ム酸とクロム酸還元生成物との合計量とシリカとの混合
比がクロム酸とクロム酸還元生成物との合計量はＣrＯ3
換算で、そしてシリカはＳiＯ2換算での重量比で１：1.
5〜2.5、かつクロム酸濃度がＣr6+として４ｇ／ｌ以
上、シリカ濃度がＳiＯ2換算で20g／ｌ以上の範囲内に
あるクロメート処理液を塗布し、最高到達板温105℃以
上で乾燥することに特徴を有するものである。Means and Action for Solving the Problems The present invention comprises, on the surface of a galvanized steel sheet, chromic acid (Cr 6+ ), a chromic acid reduction product, and colloidal silica having an average particle diameter of 10 mμ or less as main components, The mixing ratio of chromic acid and chromic acid reduction product is 1: 0.3 to 0.55 in terms of weight ratio in terms of CrO 3, respectively, and the total amount of chromic acid and chromic acid reduction product and silica are chromic acid. The total amount with the chromic acid reduction product is CrO 3
In terms of conversion, and silica is a weight ratio in terms of SiO 2 of 1: 1.
5 to 2.5, and chromic acid concentration 4g / l or higher as Cr 6+, silica concentration by applying a chromate treatment liquid is in the range of more than 20 g / l in terms of SiO 2, dried peak metal temperature 105 ° C. or higher It is characterized by doing.

【０００９】この発明は、また、亜鉛めっき鋼板表面
に、クロム酸及びクロム酸還元生成物を含む処理液を塗
布した後、水洗することなく濡れた状態で誘導加熱によ
り板温を上昇させることにより乾燥することに特徴を有
するものである。以下、この発明を詳述する。According to the present invention, a galvanized steel sheet surface is coated with a treatment liquid containing chromic acid and a chromic acid reduction product, and then the plate temperature is raised by induction heating in a wet state without washing with water. It is characterized by being dried. Hereinafter, the present invention will be described in detail.

【００１０】この発明のクロメート処理液には、少なく
ともクロム酸及びクロム酸還元生成物を含むものを用い
る。The chromate treatment liquid of the present invention contains at least chromic acid and a chromic acid reduction product.

【００１１】クロム酸は無水クロム酸（ＣrＯ3）を水に
溶解したものであり、亜鉛めっき皮膜の表面に付着して
自己補修作用を発揮し、亜鉛の白錆発生を防止する性質
を有している。クロム酸はこの性質によって亜鉛めっき
鋼板の防錆性を著しく向上させるために不可欠なもので
ある。ただし、クロム酸は可溶性であり塩水噴霧試験中
に容易に溶出するためにクロム酸の防錆性には限界があ
り、更に、保管中に大気の水分を吸収し溶解が生じ外観
が損なわれる場合もあるためにＣr6+を含んだ難溶性の
皮膜を形成する必要がある。Chromic acid is a solution of chromic anhydride (CrO 3 ) dissolved in water and has the property of adhering to the surface of the galvanized film to exert a self-repairing action and prevent white rusting of zinc. ing. Due to this property, chromic acid is indispensable for significantly improving the rust preventive property of galvanized steel sheet. However, when chromic acid is soluble and is easily eluted during the salt spray test, there is a limit to the rust resistance of chromic acid. Therefore, it is necessary to form a poorly soluble film containing Cr 6+ .

【００１２】難溶性の皮膜を形成するためには、従来の
知見から難溶性のクロム還元性生物を含んだクロメート
皮膜を形成することが有効である。In order to form a sparingly soluble film, it is effective from the conventional knowledge to form a chromate film containing a sparingly soluble chromium-reducing organism.

【００１３】その一つの方法として、クロム酸還元生成
物を添加する方法がある。クロム酸還元生成物はクロム
酸中に還元剤を添加し、クロム酸の一部を還元すること
により生成させることができる。還元した後のクロメー
ト処理液組成は、還元されていないクロム酸と還元によ
り生成する３価クロムとが主成分であり、その混合比は
還元剤の添加量によって調整する。耐食性の観点から
は、Ｃr6+とＣr3+の混合比が各々ＣrＯ3換算での重量比
で１：0.3〜1.0の範囲が優れている。ただし、クロム酸
還元生成物の混合比が高くなると液の安定性が低下し、
ゲル化してしまうばかりでなく耐黒点錆性も悪くなる。
これらの点から適当なＣr6+とＣr3+の混合比は各々Ｃr
Ｏ3換算での重量比で１：0.3〜0.55であり、1：0.35〜
0.50が好ましく、１：0.40〜0.45が特に好ましい。One of the methods is to add a chromic acid reduction product. The chromic acid reduction product can be produced by adding a reducing agent to chromic acid to reduce a part of chromic acid. The composition of the chromate treatment liquid after the reduction is mainly composed of unreduced chromic acid and trivalent chromium produced by the reduction, and the mixing ratio thereof is adjusted by the addition amount of the reducing agent. From the viewpoint of corrosion resistance, the mixing ratio of Cr 6+ and Cr 3+ is excellent in the range of 1: 0.3 to 1.0 in terms of weight ratio in terms of CrO 3 . However, when the mixing ratio of the chromic acid reduction product becomes high, the stability of the liquid decreases,
Not only does it gel, but the black spot rust resistance also deteriorates.
From these points, a suitable mixing ratio of Cr 6+ and Cr 3+ is Cr.
The weight ratio in terms of O 3 is 1: 0.3 to 0.55, and 1: 0.35 to
0.50 is preferable, and 1: 0.40 to 0.45 is particularly preferable.

【００１４】ところで、ゲル化を防止して処理液の安定
性を向上させるために鉱酸を添加することは有効であ
る。ただし、検討を行った結果、硝酸、硫酸等の酸を添
加すると耐食性が低下することが明らかになった。した
がって、処理液中に硝酸、硫酸等を添加し、処理液のｐ
Ｈを下げることによりクロム酸還元生成物を安定化させ
る方法は好ましくない。また、鉱酸のなかでリン酸は耐
食性を維持し、かつ一定範囲内であれば処理液の安定性
を向上させるので添加物として有効である。リン酸の添
加方法は、無水クロム酸中に一定量添加してから還元す
る方法、あるいは還元してからリン酸を添加する方法の
いずれも可能である。ただし、リン酸を過剰に添加する
と以下のような問題が生じる。まず、リン酸の添加量と
ともにクロメート皮膜の黄色味が低下し、更に添加する
と耐食性、処理液安定性が低下する。皮膜の黄色味が低
下するまでリン酸を添加すると、黄色系の皮膜を好むユ
ーザーに対応できなくなるため、黄色系の皮膜を形成し
たい場合には適用できない。黄色系の皮膜となるリン酸
添加量は、特公平４−20992に示されているように0.1〜
1.0ｇ／ｌ(クロム酸濃度５〜50ｇ／ｌ）である。しか
し、この範囲においてリン酸を添加すると以下のような
問題が生じる。まず、リン酸添加量が少ないと、クロム
酸還元生成物の比率が高い液において容易にゲル化す
る。また、リン酸量を増加したクロメート皮膜はアルカ
リで脱脂されたときに溶出するＣｒ量が多くなり、高温
高湿環境下で長期間保管されていると黒変化しやすくな
り、かつ塩水噴霧試験を行った場合に黒点等の発生が著
しくなる。したがって、リン酸を添加しないことが好ま
しいが、これらの特性を考慮する場合には、クロム酸と
クロム酸還元生成物との合計量とリン酸との混合比がク
ロム酸とクロム酸還元生成物との合計量はＣrＯ3換算で
の重量比で１：0.06未満の比率であることが好ましい。
このリン酸の範囲においても、先述したクロム酸還元生
成物の混合比の範囲であれば処理液を安定的に用いるこ
とができる。By the way, it is effective to add a mineral acid in order to prevent gelation and improve the stability of the treatment liquid. However, as a result of the investigation, it was revealed that the corrosion resistance was lowered when an acid such as nitric acid or sulfuric acid was added. Therefore, if nitric acid, sulfuric acid, etc. are added to the treatment liquid,
A method of stabilizing the chromic acid reduction product by lowering H is not preferable. Further, among the mineral acids, phosphoric acid is effective as an additive because it maintains the corrosion resistance and improves the stability of the treatment liquid within a certain range. The phosphoric acid can be added either by adding a fixed amount to chromic anhydride and then reducing it, or by adding phosphoric acid after the reduction. However, the excessive addition of phosphoric acid causes the following problems. First, the yellowish tint of the chromate film decreases with the amount of phosphoric acid added, and further addition decreases the corrosion resistance and treatment liquid stability. If phosphoric acid is added until the yellowness of the film decreases, it will not be possible for users who prefer a yellowish film, so it cannot be applied when a yellowish film is desired to be formed. The amount of phosphoric acid added to form a yellowish film is 0.1 to 10 as shown in Japanese Patent Publication No. 4-20992.
It is 1.0 g / l (chromic acid concentration 5 to 50 g / l). However, the addition of phosphoric acid in this range causes the following problems. First, when the addition amount of phosphoric acid is small, gelation easily occurs in a liquid having a high ratio of chromic acid reduction product. In addition, a chromate film with an increased amount of phosphoric acid has a large amount of Cr that elutes when degreased with an alkali, and tends to turn black when stored for a long time in a high-temperature and high-humidity environment, and undergoes a salt spray test. When it is done, the generation of black spots becomes significant. Therefore, it is preferable not to add phosphoric acid, but when considering these characteristics, the mixing ratio of the total amount of chromic acid and the chromic acid reduction product and phosphoric acid is chromic acid and the chromic acid reduction product. It is preferable that the total amount thereof is less than 1: 0.06 by weight in terms of CrO 3 .
Even in this range of phosphoric acid, the treatment liquid can be stably used within the range of the mixing ratio of the chromic acid reduction product described above.

【００１５】クロム酸還元生成物を皮膜中に混入させる
もう一つの方法として、クロメート処理液を塗布した後
にクロム酸還元生成物を新たに生成させる方法が考えら
れる。そこで、主にクロム酸還元生成物生成反応が進行
すると考えられる乾燥過程に着目し、特に乾燥方法の影
響について検討を行った。As another method of incorporating the chromic acid reduction product into the film, a method of newly producing the chromic acid reduction product after applying the chromate treatment liquid can be considered. Therefore, mainly focusing on the drying process in which the chromic acid reduction product formation reaction proceeds, the influence of the drying method was examined.

【００１６】乾燥方法には種々の方法があるが、基本的
に例えば熱風炉のように板の外部より加熱し乾燥する方
法と誘導加熱のように板の内部から加熱する方法があ
る。検討した結果、板の内部から加熱する誘導加熱を行
うことにより乾燥時にクロム酸還元生成物が安定して皮
膜中に生成できることが判明した。このメカニズムに関
しては明らかではないが、以下のように推定される。ク
ロメート処理液中のクロム酸とめっき表面Ｚｎの酸化還
元反応によりクロム酸還元生成物が生成する。その反応
速度は、塗布液の液温、塗布された板の板温、及び塗布
液自体の反応性によって決まり、その反応時間は主に塗
布液の水分が蒸発するまでの間であると考えられる。There are various drying methods. Basically, there are a method of heating by heating from the outside of the plate such as a hot air oven and a method of heating from inside the plate such as induction heating. As a result of examination, it was found that the chromic acid reduction product can be stably formed in the film during drying by performing induction heating in which the plate is heated. Although it is not clear about this mechanism, it is estimated as follows. A chromic acid reduction product is produced by a redox reaction between chromic acid in the chromate treatment liquid and the plating surface Zn. The reaction rate is determined by the liquid temperature of the coating liquid, the plate temperature of the coated plate, and the reactivity of the coating liquid itself, and the reaction time is considered to be mainly until the water content of the coating liquid evaporates. .

【００１７】従来の熱風を吹き付ける方法においては、
水分の蒸発と共に板温が上昇するために、鋼板の反応性
が不十分な状態で、かつ反応時間も短いためにクロメー
ト処理液と鋼板表面との反応が不安定となり、その結果
としてクロム酸還元生成物生成量が不十分かつ不安定に
なる。しかし、誘導加熱の場合には、板温が上昇するこ
とにより水分が蒸発するために板の反応性が高まった状
態でかつ反応時間も熱風方式より長くなる。従って、安
定的かつ均一な反応が可能であり、その結果、従来法と
比べて乾燥時に生成するクロム酸還元生成物が安定的に
多く生成できる。したがって、亜鉛めっき鋼板表面にク
ロム酸及びクロム酸還元生成物を含む処理液を塗布した
後濡れた状態で誘導加熱方式を用いて、この塗布液を乾
燥することにより従来のクロメート処理液での対応と全
く異なる方法にて難溶性の皮膜を形成することが可能に
なる。その他の乾燥方法として、赤外線、遠赤外線、直
火バーナー等があるが、効果の度合いに程度差があるも
のの、板の外部からの加熱が最も少ない誘導加熱と比べ
ると劣っており、かつ板温の制御も誘導加熱と比べると
難しいため、さらに有効な手段とは言えない。In the conventional method of blowing hot air,
Since the plate temperature rises with the evaporation of water, the reactivity of the steel sheet is insufficient and the reaction time between the chromate treatment solution and the steel plate surface becomes unstable, resulting in chromic acid reduction. Insufficient and unstable product production. However, in the case of induction heating, since the plate temperature rises and water evaporates, the reactivity of the plate is increased and the reaction time is longer than that of the hot air system. Therefore, a stable and uniform reaction is possible, and as a result, more chromic acid reduction products generated during drying can be stably generated as compared with the conventional method. Therefore, by applying a treatment liquid containing chromic acid and a chromic acid reduction product on the surface of a galvanized steel sheet and then using an induction heating method in a wet state, the coating liquid is dried to cope with the conventional chromate treatment liquid. It becomes possible to form a poorly soluble film by a completely different method. Other drying methods include infrared rays, far infrared rays, and direct-burning burners.However, although the degree of effectiveness is different, it is inferior to induction heating, which requires the least amount of external heating, and the plate temperature Since it is more difficult to control as compared with induction heating, it cannot be said to be an even more effective means.

【００１８】この結果から推定すると、クロメート塗布
前に板温を上昇させても効果を期待できるが本方法と比
べエネルギーロスが多くなり好ましくない。Estimating from this result, the effect can be expected even if the plate temperature is raised before the application of chromate, but this is not preferable because the energy loss becomes large as compared with the present method.

【００１９】また、従来、クロメート処理液を加温して
液の反応性を高めて使用する場合もあるが、誘導加熱を
用いて乾燥することにより液温を常温にしても従来通り
皮膜性能を得ることができる。その結果、通常数ｍ3も
あるクロメート処理液タンク内の温度を高める必要がな
くなり、エネルギーコストを低減させることが可能にな
る。Further, conventionally, the chromate-treated solution may be heated to increase the reactivity of the solution and used, but the film performance is maintained as usual even when the solution temperature is kept at room temperature by drying using induction heating. Obtainable. As a result, it is not necessary to raise the temperature in the chromate treatment tank, which is usually several m 3 , and the energy cost can be reduced.

【００２０】誘導加熱を用いて乾燥を行う場合、板幅方
向及び長さ方向で共に均一に加熱されるように誘導加熱
炉の設計することは当然必要である。その他の留意点と
して、蒸発する水分が炉内で結露して鋼板表面に落ちる
と表面欠陥となるため、結露を防止するために炉内の雰
囲気温度を室温より高く設定することも可能である。ま
た、その場合塗布液の蒸発に大きく影響しない程度であ
れば空気を送り込むことも可能である。更に、この反応
は水分が蒸発するまでの間で生じるためその後更に加熱
乾燥を行う必要がある場合には特にその加熱方法を選択
しない。本発明の特徴は、塗布されたクロメート処理液
が鋼板表面が濡れた状態のまま誘導加熱炉に入ることで
ある。When carrying out drying using induction heating, it is of course necessary to design the induction heating furnace so that both the width direction and the length direction are uniformly heated. Another point to note is that if evaporated water is condensed in the furnace and drops on the surface of the steel sheet, it becomes a surface defect. Therefore, it is possible to set the atmosphere temperature in the furnace higher than room temperature in order to prevent condensation. Further, in that case, it is also possible to feed air as long as it does not significantly affect the evaporation of the coating liquid. Further, since this reaction occurs until the water content evaporates, the heating method is not particularly selected when it is necessary to carry out further heat drying. A feature of the present invention is that the applied chromate treatment liquid enters the induction heating furnace while the surface of the steel sheet remains wet.

【００２１】さらに、耐食性、難溶性等の他に耐指紋
性、塗装性等が要求されるが、これらに対してはコロイ
ダルシリカ（湿式シリカ）の添加が有効である。コロイ
ダルシリカは、そのシリカ粒子径と添加量により特性が
大きく影響される。耐食性、耐指紋性の観点からは、シ
リカ粒子径が数10ｍμ以下で、かつその添加量がクロム
酸とクロム酸還元生成物との合計量とシリカとの混合比
がクロム酸とクロム酸還元生成物との合計量はＣrＯ3換
算での重量比で、そしてシリカはＳiＯ2換算での重量比
で１：1.5〜4.0の比率であることが必要である。塗装性
に関しては、シリカが一定量以上付着すると逆に低下す
る。したがって、シリカの添加量は、クロム酸とクロム
酸還元生成物との合計量とシリカとの混合比がクロム酸
とクロム酸還元生成物との合計量はＣrＯ3換算での重量
比で、シリカはＳiＯ2換算での重量比で１：1.5〜2.5の
比率であることが必要である。Furthermore, in addition to corrosion resistance, poor solubility, etc., fingerprint resistance, paintability, etc. are required, and addition of colloidal silica (wet silica) is effective for these. The characteristics of colloidal silica are greatly affected by the particle size of silica and the amount added. From the viewpoint of corrosion resistance and fingerprint resistance, the silica particle size is several tens of μm or less, and the addition amount is the total amount of chromic acid and chromic acid reduction product, and the mixing ratio of silica is chromic acid and chromic acid reduction product. It is necessary that the total amount with the substance is a weight ratio in terms of CrO 3 , and that the silica is 1: 1.5 to 4.0 in a weight ratio in terms of SiO 2 . Concerning the coatability, when silica adheres in a certain amount or more, it deteriorates. Therefore, the amount of silica added is such that the total amount of chromic acid and a chromic acid reduction product and the mixing ratio of silica are chromic acid and a chromic acid reduction product, and the total amount of silica is a weight ratio in terms of CrO 3. Should be 1: 1.5 to 2.5 in terms of weight ratio in terms of SiO 2 .

【００２２】また、耐黒点錆性の観点からリン酸を添加
しない、あるいは添加しても極微量であるために、シリ
カの平均粒子径が15ｍμ以上のコロイダルシリカを用い
ると耐食性がリン酸を添加した処理液で得られる皮膜よ
り低下する。これに対して、シリカの平均粒子径を10ｍ
μ以下にするとリン酸添加による影響が小さく、添加し
なくとも良好な耐食性が得られることを見いだした。こ
のメカニズムについては明らかではないが、推定するに
リン酸を添加することによりリン酸クロム等が生成さ
れ、これがかなり細かな粒子となり皮膜のバリヤー性を
高める変わりに、シリカの粒子径を細かくすることによ
り同様の緻密な皮膜が形成されるためにリン酸添加の必
要がなくなるためと考えられる。ただし、シリカの粒子
径を必要以上に小さくすると処理液の安定性が低下する
ことが懸念される。安定性と耐食性の観点から、シリカ
の平均粒子径は４〜10ｍμにすることが好ましい。Further, from the viewpoint of black spot rust resistance, phosphoric acid is not added, or even if it is added in a very small amount, when colloidal silica having an average particle size of silica of 15 mμ or more is used, the corrosion resistance is phosphoric acid added. It is lower than the film obtained with the treated liquid. On the other hand, the average particle size of silica is 10 m
It has been found that when the content is less than μ, the effect of addition of phosphoric acid is small, and good corrosion resistance can be obtained without addition. The mechanism is not clear, but it is presumed that addition of phosphoric acid produces chromium phosphate, which becomes fine particles and increases the barrier property of the film. Instead, the particle size of silica should be reduced. It is considered that the addition of phosphoric acid becomes unnecessary because a similar dense film is formed by the above. However, if the particle size of silica is made smaller than necessary, there is concern that the stability of the treatment liquid may be reduced. From the viewpoint of stability and corrosion resistance, the average particle size of silica is preferably 4 to 10 mμ.

【００２３】本発明の中で用いられるシリカの特徴は、
平均粒子径10ｍμ以下のコロイダルシリカを用い、添加
量をクロム酸化合物の1.5〜2.5倍としたことであり、こ
れによりはじめて耐食性、耐黒点錆性、耐指紋性、塗装
性、処理液安定性の全てにおいて優れた処理液を提供で
きることにある。The characteristics of the silica used in the present invention are:
Colloidal silica with an average particle size of 10mμ or less was used, and the amount added was 1.5 to 2.5 times that of the chromic acid compound. This was the first time that corrosion resistance, black spot rust resistance, fingerprint resistance, paintability, and treatment liquid stability were improved. It is to be able to provide an excellent processing liquid in all cases.

【００２４】更に、高温高湿環境においてもめっき表面
が黒変化しない様にするための手段としては、処理液中
にＺｎ化合物を添加し、Ｃr6+とＺｎとの混合比が重量
比で1：0.06〜0.3にする、あるいは処理液のｐＨを2.3
以上にすることが有効である。耐黒変性に対してはめっ
き中に混入するＰｂ量の影響が大きいが、Ｐｂを皆無に
することは現状の技術では困難である。その結果、めっ
き中にＮｉ等を添加する方法、あるいはめっき表面にＮ
ｉ等を付着させる方法等により対策がとられている。但
し、これらの方法は、いずれもＮｉ等の高価な元素を必
要とするためにコスト高となり、更に安易な対策が望ま
れている。添加するＺｎ化合物としては、ＺｎＯ等の安
価なもので効果があり、したがって従来の方法と比べる
とコスト的に有利である。耐黒変性についてはめっき表
面のＺｎ酸化物の状態が大きく影響し、ｐＨが低い場合
にはこの酸化物が溶解してしまうために耐黒変性が低下
すると推定される。クロメート処理液中にＺｎ化合物を
添加することにより耐黒変性が向上するメカニズムは、
めっき表面のＺｎ酸化物の溶解がＺｎ化合物添加により
抑制され、その結果として耐黒変性が向上すると考えら
れる。Ｚｎ化合物は、添加と共に処理液のｐＨが上昇す
るもので効果が認められ、ＺｎＯのほかＺｎの水酸化
物、炭酸塩等に効果が認められた。また、Ｚｎ化合物以
外の添加物について限定していない理由はコスト的に見
て大きなメリットがあるものがないことによる。但し、
Ｃr6+に対して重量比でＺｎを0.3より多く添加すると、
全て溶解することが難しく沈殿物が生じる、あるいは処
理時に処理液のｐＨが３を越える場合がある。このよう
な場合には処理液が不安定となるために好ましくない。
したがって、添加するＺｎ化合物量は、Ｚｎ量として処
理液中のＣr6+量にたいして0.3以下にすべきである。次
に、処理液の塗布方法について述べる。Further, as a means for preventing the plating surface from blackening even in a high temperature and high humidity environment, a Zn compound is added to the treatment liquid, and the mixing ratio of Cr 6+ and Zn is 1 by weight. : 0.06 to 0.3, or the pH of the processing solution is 2.3
The above is effective. The amount of Pb mixed in during plating has a great influence on the blackening resistance, but it is difficult to eliminate Pb entirely by the current technology. As a result, a method of adding Ni or the like during plating or N on the plating surface
Measures are taken by a method of attaching i or the like. However, all of these methods require expensive elements such as Ni, resulting in high cost, and further easier measures are desired. As the Zn compound to be added, an inexpensive one such as ZnO is effective and is therefore advantageous in cost as compared with the conventional method. It is presumed that the resistance to blackening is greatly affected by the state of the Zn oxide on the plating surface, and when the pH is low, the oxide dissolves, resulting in a decrease in blackening resistance. The mechanism of improving the blackening resistance by adding a Zn compound to the chromate treatment solution is
It is considered that dissolution of Zn oxide on the plating surface is suppressed by the addition of the Zn compound, and as a result, blackening resistance is improved. The effect of the Zn compound was recognized in that the pH of the treatment liquid increased with the addition, and the effect was recognized in ZnO as well as Zn hydroxide and carbonate. Further, the reason why the additives other than the Zn compound are not limited is that there is no significant merit in terms of cost. However,
When Zn is added in a weight ratio of more than 0.3 with respect to Cr 6+ ,
In some cases, it is difficult to dissolve them all and a precipitate is generated, or the pH of the treatment liquid during treatment may exceed 3. In such a case, the treatment liquid becomes unstable, which is not preferable.
Therefore, the amount of Zn compound added should be 0.3 or less with respect to the amount of Cr 6+ in the processing liquid as the amount of Zn. Next, a method of applying the treatment liquid will be described.

【００２５】塗布方法については付着量の均一化あるい
は調整を行うために、浸漬またはスプレーにより鋼板表
面に塗布した後、気体絞りあるいはロール絞りを行う方
法、あるいはロールコーティング方法等が上げられる。
しかし、これらの方法によれば、はじきと見られる塗布
欠陥が生じる場合がある。従来、塗布性を向上させる手
段としてリン酸を添加していたが、本発明においては基
本的にリン酸を添加しない。そのため、リン酸に代わる
塗布性向上方法の検討が必要になった。クロメート処理
液の塗布性について検討した結果、Ｃr6+濃度が4ｇ／ｌ
未満の場合、あるいはシリカ濃度が20ｇ／ｌ未満で処理
した場合に塗布欠陥が生じやすいことが明らかになっ
た。したがって、塗布性の観点からは、Ｃr6+濃度が4ｇ
／ｌ以上でかつシリカ濃度は20ｇ／ｌ以上の処理液を塗
布することが必要不可欠である。但し、誘導加熱により
乾燥を行った場合には、先述のように皮膜の着色度が緩
和されるために塗布欠陥を目立ちにくくすることはでき
る。また、好ましいＣｒ付着量範囲は各種特性のバラン
スから30〜80mg／ｍ2で有り、したがって、塗布方法と
してはＣr6+濃度が4ｇ／ｌ以上でかつシリカ濃度は20ｇ
／ｌ以上の処理液をその適性範囲内に調整できる方法で
あれば良い。乾燥の際に誘導加熱を用いることによる効
果を充分に発揮させるためには、塗布した後乾燥炉で塗
布液の水分を蒸発させるにあたり、濡れた状態のまま乾
燥炉に挿入することが必要である。気体絞りの場合、絞
った時点でかなり乾燥されるためあまり好ましくない
が、方法等を工夫し、乾燥が進まないようにすれば利用
することが可能である。特に、いずれの方法においても
乾燥しないように処理液の濃度、塗布液のＷｅｔ量等を
調整することは有力な手段である。As for the coating method, in order to make the amount of coating uniform or to adjust the coating amount, a method of dipping or spraying the surface of the steel sheet and then gas or roll squeezing, or a roll coating method can be used.
However, according to these methods, coating defects which are considered to be repellants may occur. Conventionally, phosphoric acid has been added as a means for improving coatability, but in the present invention, phosphoric acid is basically not added. Therefore, it has become necessary to study a method of improving the coating property instead of phosphoric acid. As a result of examining the coating property of the chromate treatment liquid, the Cr 6+ concentration was 4 g / l.
It has been revealed that coating defects are likely to occur when the amount is less than 20% or when the silica concentration is less than 20 g / l. Therefore, from the viewpoint of coating property, the Cr 6+ concentration is 4 g.
/ L or more and the silica concentration is 20 g / l or more. However, when drying is performed by induction heating, the degree of coloring of the film is relaxed as described above, so that coating defects can be made inconspicuous. In addition, the preferable Cr deposition amount range is 30 to 80 mg / m 2 in view of the balance of various characteristics. Therefore, as a coating method, the Cr 6+ concentration is 4 g / l or more and the silica concentration is 20 g.
Any method can be used as long as it is possible to adjust the treatment liquid of 1 / l or more within the proper range. In order to fully bring out the effect of using induction heating during drying, it is necessary to insert the wet state into the drying oven when the water content of the coating solution is evaporated in the drying oven after coating. . In the case of gas squeezing, it is not so preferable because it is considerably dried at the time of squeezing, but it can be used by devising a method or the like so that the drying does not proceed. In particular, adjusting the concentration of the treatment liquid, the amount of Wet of the coating liquid and the like so as not to dry in any of the methods is an effective means.

【００２６】次に、塗布された液の乾燥方法について述
べる。乾燥炉の方式は特に規定するものではないが、先
述したように誘導加熱により乾燥を行うことにより難溶
性で外観均一性にも優れたクロメート処理鋼板を製造で
きる。乾燥板温はクロメート皮膜特性に大きく影響す
る。乾燥板温が50℃以下ではクロメート処理液が乾燥し
きらず明らかに不適切である。乾燥板温が60〜100℃の
範囲に於いては、外観から判断するかぎり乾燥した皮膜
が得られるが、耐食性が処理した後の経時とともに低下
しやすい問題がある。この理由として、乾燥板温が60〜
100℃の範囲での乾燥では、外観的には乾燥しているよ
うに見えるが、まだ、吸着水、あるいはクロム酸化合物
からの脱水反応により生じる水分はかなり残存している
ために皮膜中の６価クロムとＺｎとの反応が保管時にも
容易に進行し、耐食性の観点から必要な６価クロムが著
しく減少するためと推定される。皮膜の経時安定性を確
保するためには、到達板温で105℃以上の乾燥が必要で
あることが判明した。更に、耐黒点錆性について乾燥板
温の影響を検討した結果、リン酸を添加しない系におい
ても、100℃以下の乾燥では発生しやすい。乾燥板温の
上限については250℃まで性能的に優れているが、必要
な設備が膨大になることもあり、製造ラインの状況によ
って決めればよい。実用的観点から105〜180℃程度が適
当であり、110〜140℃程度が好ましい。Next, a method for drying the applied liquid will be described. The method of the drying furnace is not particularly specified, but as described above, it is possible to manufacture a chromate-treated steel sheet that is hardly soluble and has excellent appearance uniformity by performing drying by induction heating. Drying plate temperature greatly affects the chromate film properties. If the drying plate temperature is 50 ° C or lower, the chromate treatment solution is not completely dried, which is obviously inappropriate. When the drying plate temperature is in the range of 60 to 100 ° C, a dried film can be obtained as judged from the appearance, but there is a problem that the corrosion resistance tends to decrease with time after the treatment. The reason for this is that the drying plate temperature is 60-
When it is dried in the range of 100 ° C, it looks like it is dry in appearance, but since the water generated by the dehydration reaction from the adsorbed water or the chromic acid compound still remains considerably, 6 It is presumed that the reaction between the valent chromium and Zn easily proceeds even during storage, and the hexavalent chromium required from the viewpoint of corrosion resistance is significantly reduced. It was found that in order to secure the stability of the film over time, it is necessary to dry at a reached plate temperature of 105 ° C or higher. Furthermore, as a result of studying the influence of the drying plate temperature on the black spot rust resistance, it is likely to occur even in a system to which phosphoric acid is not added, at a temperature of 100 ° C or lower. The upper limit of the drying plate temperature is excellent up to 250 ° C in terms of performance, but the required equipment may be enormous and may be determined depending on the conditions of the production line. From a practical viewpoint, about 105 to 180 ° C is suitable, and about 110 to 140 ° C is preferable.

【００２７】本発明に使用可能な被処理材は電気めっき
プロセス、溶融めっきプロセス、蒸着めっきプロセス等
により製造される亜鉛系めっき鋼板であり、純亜鉛めっ
き鋼板のほか、Ｆｅ−Ｚｎ系合金めっき、Ａｌ−Ｚｎ系
合金めっき、Ｚｎ−Ａｌ系合金めっき、Ｚｎ−Ｎｉ系合
金めっき鋼板に用いることが可能である。The material to be treated that can be used in the present invention is a zinc-based plated steel sheet produced by an electroplating process, a hot dip plating process, a vapor deposition plating process, and the like. It can be used for Al-Zn alloy plating, Zn-Al alloy plating, and Zn-Ni alloy plating steel sheet.

【００２８】[0028]

【実施例】【Example】

実施例１ 公知の方法でめっきされた電気亜鉛めっき鋼板(めっき
量片面当り20ｇ／ｍ2）表面にロールコーターを用い
て、表１に示した組成のクロメート処理液を塗布した。
塗布後、直ちに熱風乾燥炉にて10秒間で板温が110℃に
なるように乾燥した。表１中のＣrＯ3はクロム酸（Ｃr
6+）とクロム酸還元生成物（Ｃr3+）の合計量(ｇ／ｌ）
を示す。クロム酸還元生成物（Ｃr3+）は、公知の方法
により生成させ、Ｃr3+／Ｃr6+をクロム酸溶液中へのサ
ッカロース添加量にて調整した。ＳiＯ2は、市販のコロ
イダルシリカで平均粒子径８ｍμのもの、リン酸は市販
の正リン酸（Ｈ3ＰＯ4）を用いた。Example 1 A chromate treatment liquid having the composition shown in Table 1 was applied to the surface of an electrogalvanized steel sheet (plating amount: 20 g / m 2 per side) plated by a known method using a roll coater.
Immediately after coating, the plate was dried in a hot air drying oven for 10 seconds so that the plate temperature became 110 ° C. CrO 3 in Table 1 is chromic acid (Cr
6+ ) and chromic acid reduction product (Cr 3+ ) (g / l)
Indicates. The chromic acid reduction product (Cr 3+ ) was produced by a known method, and Cr 3+ / Cr 6+ was adjusted by the amount of sucrose added to the chromic acid solution. As SiO 2 , commercially available colloidal silica having an average particle size of 8 mμ was used, and as phosphoric acid, commercially available orthophosphoric acid (H 3 PO 4 ) was used.

【００２９】クロメート処理液の安定性は、50℃で１ヵ
月間放置した後の液の状態を観察した。Regarding the stability of the chromate-treated solution, the state of the solution after observing for 1 month at 50 ° C. was observed.

【００３０】クロメート処理材のＣr付着量は、蛍光Ｘ
線による定量分析により求めた。The amount of Cr deposited on the chromate-treated material is determined by the fluorescence X
It was determined by quantitative analysis using a line.

【００３１】クロメード処理材の耐食姓は、塩水噴霧試
験（ＪＩＳ Ｚ 2371）を行い、白錆発生面積が10％未満
に抑制されている試験時間（ｈ）により評価した。同時
に塩水噴霧試験100h経過した時点で表面の黒点錆発生程
度を観察し、下記に示す基準により耐黒点錆性を評価し
た。The corrosion resistance of the chromed material was evaluated by a salt spray test (JIS Z 2371), and the test time (h) in which the white rust generation area was suppressed to less than 10%. At the same time, after 100 hours of the salt spray test, the degree of black spot rust generation on the surface was observed, and the black spot rust resistance was evaluated according to the following criteria.

【００３２】耐黒点錆性評価基準； １…全面に多数発生し、斜めから観察すると白錆に見え
る ２…全面に多数発生するが、斜めから観察しても黒く見
える ３…２よりかなり発生密度が低い ４…わずかに発生 ５…発生なしCriteria for evaluation of black spot rust resistance; 1 ... Many occur on the entire surface and appear white rust when observed obliquely 2 ... Many occur on the entire surface, but appear black even when observed obliquely 3 ... Significantly higher density than 2 Low 4 ... Slightly occurred 5 ... No occurrence

【００３３】[0033]

【表１】 [Table 1]

【００３４】Ｎo.１〜７は、リン酸を含まないクロメー
ト処理液で、耐食性はＣr3+／Ｃr6+＝0.3〜1.0の範囲で
優れた特性を有している。しかし、耐黒点性、および処
理液安定性は、Ｃr3+／Ｃr6+＝０〜0.55の範囲で優れて
おり、耐食性、耐黒点錆性、処理液安定性全て満足する
ためには、Ｃr3+／Ｃr6+＝0.3〜0.55にすることが必要
であることがわかる。Ｎo.８〜10はリン酸を添加したク
ロメート処理液で、Ｃr3+／Ｃr6+＝0.3〜0.55の範囲で
あってもリン酸添加量が請求範囲外になると耐黒点錆性
が著しく低下する。Nos. 1 to 7 are chromate treatment liquids containing no phosphoric acid, and have excellent corrosion resistance in the range of Cr 3+ / Cr 6+ = 0.3 to 1.0. However, the black spot resistance and the processing solution stability are excellent in the range of Cr 3+ / Cr 6+ = 0 to 0.55, and in order to satisfy all of the corrosion resistance, the black spot rust resistance, and the processing solution stability, Cr is required. It can be seen that it is necessary to set 3 + / Cr 6+ = 0.3 to 0.55. Nos. 8 to 10 are chromate treatment liquids to which phosphoric acid is added. Even if Cr 3+ / Cr 6+ = 0.3 to 0.55, if the amount of phosphoric acid added is out of the claimed range, the black spot rust resistance remarkably decreases. To do.

【００３５】実施例２ 実施例１と同様に表２に示した組成のクロメート処理液
により電気亜鉛めっき鋼板を処理した。これらの液のＣ
rＯ3濃度は13ｇ／ｌ、Ｃr3+／Ｃr6+は0.43に調整した。
塗布後、直ちに熱風乾燥炉にて10秒間で板温が110℃に
なるように乾燥した。また、実施例１と同様の方法によ
り、Ｃｒ付着量を求め、耐食性、耐黒点錆性、処理液安
定性を評価した。また、特性に及ぼす処理液安定性の影
響を調べる目的で、処理液安定性を試験した後の液によ
り処理したサンプルの耐食性を評価した。塗布密着性は
市販のメラミン系塗料で塗装（30μｍ）した後、１mm間
隔の基盤目を100個カッターで切り、その部分をエリク
セン試験機にて5mm押し出し、粘着テープにて剥離試験
を行い、下記に示す評価基準に基づき密着性を評価し
た。Example 2 An electrogalvanized steel sheet was treated with a chromate treatment solution having the composition shown in Table 2 in the same manner as in Example 1. C of these liquids
The rO 3 concentration was adjusted to 13 g / l, and Cr 3+ / Cr 6+ was adjusted to 0.43.
Immediately after coating, the plate was dried in a hot air drying oven for 10 seconds so that the plate temperature became 110 ° C. In addition, the Cr deposition amount was determined by the same method as in Example 1, and the corrosion resistance, black spot rust resistance, and treatment liquid stability were evaluated. Further, for the purpose of investigating the influence of the treatment liquid stability on the characteristics, the corrosion resistance of the sample treated with the liquid after the treatment liquid stability was tested was evaluated. After coating with commercially available melamine-based paint (30 μm), 100 pieces of substrate with 1 mm intervals are cut with a cutter, and that portion is extruded by 5 mm with an Erichsen tester and subjected to a peel test with an adhesive tape. Adhesion was evaluated based on the evaluation criteria shown in.

【００３６】塗料密着性評価基準； １…全て剥離 ２…50％以上剥離 ３…25〜49％剥離 ４…10〜24％剥離 ５…剥離面積10％未満Criteria for evaluating paint adhesion; 1 ... All peeling 2 ... 50% or more peeling 3 ... 25-49% peeling 4 ... 10-24% peeling 5 ... Peeling area less than 10%

【００３７】[0037]

【表２】 [Table 2]

【００３８】Ｎo.11〜14は、コロイダルシリカの平均粒
子径を変えたクロメート処理液での特性を示している。
Ｎo.15は、公知の比較材でリン酸を含んだものである。
平均粒子径を小さくするほど耐食性は向上しており、平
均粒子径を10ｍμ以下にすることによりリン酸を含まな
くとも公知の比較材と同等以上の耐食性を有している。
処理液安定性は、いずれの処理液においても外観的には
異常を認められない。処理液安定性を評価した後の液で
処理したサンプルの耐食性は、上述した傾向と大差無い
が、５ｍμのシリカを添加した処理液での耐食性は８ｍ
μのシリカを添加したものと同じレベルにまで低下して
いるが、その他と比べると優れている。Ｎo.17はシリカ
添加量が請求範囲より少ない場合で有り、耐食性に劣っ
ている。Ｎo.18はシリカ添加量が請求範囲より多い場合
で有り、塗料密着性に劣っている。Nos. 11 to 14 show the characteristics of the chromate-treated liquid in which the average particle diameter of colloidal silica was changed.
No. 15 is a known comparative material containing phosphoric acid.
The smaller the average particle size is, the more the corrosion resistance is improved. By setting the average particle size to 10 mμ or less, the corrosion resistance is equal to or higher than that of the known comparative material without containing phosphoric acid.
Regarding the stability of the treatment liquids, no abnormality is observed in appearance in any of the treatment liquids. The corrosion resistance of the sample treated with the solution after evaluating the stability of the processing solution is not much different from the tendency described above, but the corrosion resistance of the processing solution containing 5 mμ of silica is 8 m.
Although it is reduced to the same level as the one to which μ silica is added, it is superior to others. No. 17 is the case where the added amount of silica is less than the claimed range and the corrosion resistance is poor. No. 18 is the case where the amount of silica added is larger than the claimed range, and the coating adhesion is poor.

【００３９】実施例３ 実施例１と同様に表３に示す組成のクロメート処理液に
より電気亜鉛めっき鋼板を処理した。添加したシリカは
粒子径８ｍμのものを用いた。ただし、クロム酸濃度の
異なる処理液については、ロールコータの塗布条件を調
整することにより一定のＣｒ付着量を得た。また、クロ
メート処理液を塗布した後の乾燥温度を変えてクロメー
ト皮膜を形成した処理材について実施例１と同様の方法
により、Ｃr付着量を求め、耐食性、耐黒点錆性を評価
した。また、耐食性の経時安定性を評価する目的で80
℃、95％ＲＨ環境下で24ｈ保管した後、塩水噴霧試験を
行った。塗布外観については、その均一性を目視観察し
下記に示す評価基準に基づいて評価した。Example 3 An electrogalvanized steel sheet was treated with a chromate treatment solution having the composition shown in Table 3 in the same manner as in Example 1. The added silica had a particle diameter of 8 mμ. However, for the treatment liquids having different chromic acid concentrations, a constant Cr adhesion amount was obtained by adjusting the coating conditions of the roll coater. Further, with respect to the treated material on which the chromate film was formed by changing the drying temperature after applying the chromate treatment liquid, the Cr adhesion amount was determined by the same method as in Example 1 to evaluate the corrosion resistance and the black spot rust resistance. In addition, for the purpose of evaluating the stability of corrosion resistance with time,
After storing in a 95 ° C RH environment for 24 hours, a salt spray test was conducted. The coating appearance was evaluated by visually observing the uniformity and based on the evaluation criteria shown below.

【００４０】塗布外観均一性評価基準； Ａ…斜めから観察してもムラが無い Ｂ…斜めから観察すると解かる程度のムラ有り Ｃ…明らかにムラ有りCriteria for evaluating uniformity of coating appearance; A ... No unevenness even when observed obliquely B ... There is unevenness that can be seen when observed obliquely C ... Clearly uneven

【００４１】[0041]

【表３】 Ｎo.19，20は、クロメート処理液組成は請求範囲内であ
るが、乾燥板温が請求範囲外である。そのためにＮo.2
1，22，23と比べ耐黒点錆性、経時後の耐食性に劣る。
Ｎo.25，26は、Ｃr6+濃度、ＳiＯ2濃度が請求範囲外で
あるために塗布外観の均一性に劣っている。[Table 3] In Nos. 19 and 20, the composition of the chromate treatment liquid is within the claimed range, but the dry plate temperature is outside the claimed range. Therefore, No.2
Compared with 1, 22, 23, it is inferior in black spot rust resistance and corrosion resistance after aging.
In Nos. 25 and 26, the Cr 6+ concentration and the SiO 2 concentration were out of the claimed ranges, so that the uniformity of the coating appearance was poor.

【００４２】実施例４ 電気亜鉛めっき鋼板に表４に示す組成のクロメート処理
液をロールコーターにより塗布し、直ちに乾燥を行っ
た。クロメート処理液のｐＨは、ＺｎＯの添加量を変え
ることにより調整した。Example 4 An electrogalvanized steel sheet was coated with a chromate treatment solution having the composition shown in Table 4 by a roll coater and immediately dried. The pH of the chromate treatment liquid was adjusted by changing the addition amount of ZnO.

【００４３】耐黒変性評価方法； 黒変促進試験条件：80℃，95％ｐＨの環境に24ｈ放置 評価方法：色差計によりサンプル明度（Ｌ値）を測定
し、促進試験前後でのΔＬ｛＝（試験後のＬ値）−（試
験前のＬ値）｝により評価した。ΔＬ≧−２の場合に
は、目視にて黒変化を確認できないレベルであり実際的
には問題にならないレベルである。Black discoloration resistance evaluation method; Black discoloration acceleration test condition: left for 24 hours in an environment of 80 ° C., 95% pH Evaluation method: sample brightness (L value) was measured by a color difference meter, and ΔL {= (L value after the test)-(L value before the test)}. When ΔL ≧ −2, it is a level at which black change cannot be visually confirmed, and is a level at which there is no practical problem.

【００４４】[0044]

【表４】 [Table 4]

【００４５】本発明例の中でも、乾燥方式によらず、処
理液のｐＨが2.2以下の場合（Ｎo.27，28，29）には、
耐黒変性は不十分である。処理液のｐＨが更に高くなる
と、耐黒変性も明らかに向上している（Ｎo.33，31，3
2，33）。Among the examples of the present invention, when the pH of the treatment liquid is 2.2 or less (No. 27, 28, 29) regardless of the drying method,
The resistance to blackening is insufficient. When the pH of the treatment liquid is further increased, the blackening resistance is obviously improved (No. 33, 31, 3).
2, 33).

【００４６】実施例５ 実施例１と同様に表５に示した組成のクロメート処理液
により電気亜鉛めっき鋼板を処理した。クロメート処理
液の乾燥手段として、熱風炉による方法と誘導加熱によ
る方法を用いた。形成された皮膜の難溶性を評価する手
段として、処理材をアルカリ脱脂し、そのＣｒ残存率に
より評価した。Example 5 An electrogalvanized steel sheet was treated with a chromate treatment solution having the composition shown in Table 5 in the same manner as in Example 1. As a method for drying the chromate treatment liquid, a method using a hot air oven and a method using induction heating were used. As a means for evaluating the poor solubility of the formed film, the treated material was degreased with alkali and evaluated by the Cr residual rate.

【００４７】脱脂後Ｃｒ残存率測定方法；脱脂前後にお
いてＣｒ付着量を測定し、（脱脂後Ｃｒ付着量）／（脱
脂前Ｃｒ付着量）を脱脂後Ｃｒ残存率とした。脱脂液に
は、市販の脱脂剤(ＦＣＮ−364Ｓ，日本パーカライジン
グ社製）を用い20ｇ／ｌで建浴したものを用いた。脱脂
液の液温60℃にて、120秒間スプレー脱脂を行った。Method of measuring Cr residual rate after degreasing: The amount of deposited Cr was measured before and after degreasing, and the (Cr deposited amount after degreasing) / (Cr deposited before degreasing) was defined as the residual Cr percentage after degreasing. As the degreasing solution, a bath solution prepared using a commercially available degreasing agent (FCN-364S, manufactured by Nippon Parkerizing Co., Ltd.) at 20 g / l was used. Spray degreasing was performed for 120 seconds at a degreasing liquid temperature of 60 ° C.

【００４８】[0048]

【表５】 [Table 5]

【００４９】熱風炉にて乾燥した皮膜(Ｎo.35，Ｎo.3
6）は、到達板温110℃にて優れた耐食性が得られるが、
脱脂を行った場合には、到達板温を140℃にしてもクロ
メート皮膜中のＣｒ残存率は65％である。また、処理液
中のＣr6+に対するＣr3+比率を高めても70％程度である
（Ｎo.34）。これに対して、誘導加熱（Ｉ.Ｈ.）を用い
て乾燥した皮膜（Ｎo.37〜44）は、いずれの条件におい
ても85％以上のＣｒが残存しており、飛躍的により好ま
しい皮膜が形成されている。この中でＮo.37は、耐食性
が劣るが、乾燥時の昇温パターン（Ｎo.38）、到達板温
（Ｎo.39）、炉内雰囲気温度（Ｎo.40，41）を調整する
ことにより耐食性に優れる皮膜をＩ.Ｈ.により短時間で
形成することができる。Films dried in a hot air oven (No. 35, No. 3
6) gives excellent corrosion resistance at the ultimate plate temperature of 110 ° C,
When degreasing is performed, the Cr residual ratio in the chromate film is 65% even when the ultimate plate temperature is 140 ° C. Further, even if the ratio of Cr 3+ to Cr 6+ in the treatment liquid is increased, it is about 70% (No. 34). On the other hand, in the coatings (No. 37 to 44) dried by using induction heating (I.H.), 85% or more of Cr remains in any condition, which is a dramatically more preferable coating. Has been formed. Among these, No. 37 has poor corrosion resistance, but by adjusting the temperature rise pattern (No. 38) during drying, the ultimate plate temperature (No. 39), and the furnace atmosphere temperature (No. 40, 41) A film excellent in corrosion resistance can be formed by I.H. in a short time.

【００５０】また、Ｎo.42〜46は、クロメート処理液中
にＺｎＯを添加した場合であるが、皮膜性能に対しては
悪影響を及ぼさず目的の特性を有している。Nos. 42 to 46 are cases in which ZnO was added to the chromate treatment liquid, but they did not adversely affect the film performance and had the desired characteristics.

【００５１】実施例４、５で得られたクロメート処理液
中に添加したＺｎＯと、ロールコーターで塗布した場合
の処理液に混入するＺｎ量の関係を図４に示す。これか
ら、Ｚｎ化合物を添加することによりめっきからのＺｎ
化合物の混入が抑制されていることが解かる。この効果
により耐黒変性を向上させていると考えられる。FIG. 4 shows the relationship between ZnO added to the chromate treatment liquids obtained in Examples 4 and 5 and the amount of Zn mixed in the treatment liquid when coated with a roll coater. From this, Zn from the plating was added by adding a Zn compound.
It can be seen that the compound contamination is suppressed. It is considered that this effect improves the blackening resistance.

【００５２】実施例６ 公知の方法でめっきされた電気亜鉛めっき鋼板(めっき
量片面あたり20g／ｍ2)、あるいは溶融亜鉛めっき鋼板
(めっき量片面あたり60ｇ／ｍ2，ミニマイズド処理）表
面にロールコーターを用いて、表６に示した組成のクロ
メート処理液を塗布した。塗布後直ちに誘導加熱炉ある
いは熱風吹き付け炉にて乾燥を行った。Example 6 Electrogalvanized steel sheet plated by a known method (plating amount: 20 g / m 2 per side) or hot-dip galvanized steel sheet
(Plate amount: 60 g / m 2 on one side, minimized treatment) A chromate treatment liquid having the composition shown in Table 6 was applied to the surface using a roll coater. Immediately after coating, drying was performed in an induction heating furnace or a hot air blowing furnace.

【００５３】各サンプルの色調を色差計により測定し、
黄色味の指標となるｂ値により評価した。また、外観均
一性を目視評価した。The color tone of each sample was measured with a color difference meter,
It was evaluated by the b value, which is an index of yellowness. Further, the appearance uniformity was visually evaluated.

【００５４】めっき皮膜；ＥＧ…電気亜鉛めっき鋼板 ＣＧ…溶融亜鉛めっき鋼板 Ｃｒ濃度；塗布液中に含まれるＣｒを金属Ｃｒ換算した
値 Ｃｒ還元率；塗布液中に含まれるＣr6+とＣr3+の重量比
を（Ｃr3+）／（Ｃr3+＋Ｃr6+）にて換算した値 リン酸；塗布液中に含まれるリン酸量をＨ3ＰＯ4にて換
算した値 シリカ；市販のシリカコロイドを添加 有機高分子；アクリル系エマルジョン樹脂を添加し、塗
布液中に含まれる樹脂固形分濃度を示す 乾燥方式；熱風…熱風循環炉 Ｉ.Ｈ.…誘導加熱炉 外観均一性評価基準； ５…均一 ４…塗布時には若干ムラがあるが、乾燥すると若干ムラ
が確認できる程度 ３…塗布時には均一であるが、乾燥すると若干ムラが確
認できる程度 ２…塗布時には均一であるが、乾燥するとムラが目立つ １…ムラがかなり目立つPlating film; EG ... Electrogalvanized steel sheet CG ... Hot-dip galvanized steel sheet Cr concentration; Cr conversion in the coating solution converted to metallic Cr Cr reduction rate; Cr 6+ and Cr 3 contained in the coating solution Value obtained by converting the weight ratio of + into (Cr 3+ ) / (Cr 3+ + Cr 6+ ) phosphoric acid; value obtained by converting the amount of phosphoric acid contained in the coating liquid with H 3 PO 4 silica; commercially available Silica colloid is added Organic polymer; Acrylic emulsion resin is added to show the solid content of resin contained in the coating liquid Drying method; Hot air ... Hot air circulation oven I.H .... Induction heating oven Appearance uniformity evaluation standard; 5 ... Uniform 4 ... Some unevenness during coating, but slight unevenness can be confirmed when dried 3 ... Even when coated, even slight unevenness can be confirmed when dried 2 ... Even when coated, uneven when dried Is noticeable 1 ... Stand out will

【００５５】[0055]

【表６】 [Table 6]

【００５６】Ｎo.47、48は、クロム酸、クロム酸還元生
成物、リン酸からなるクロメート処理液の例であり、均
一な塗布がかなり困難な液である。熱風方式の場合、
Ｉ.Ｈ.で乾燥したものに比べて黄色味が強くなり、乾燥
後の処理ムラが目立つ。Ｉ.Ｈ.で乾燥を行うことにより
黄色味が薄くなるため外観がかなり均一になるが、塗布
ムラが原因と考えられる明度のバラツキがあり、ムラが
若干残っている。Nos. 47 and 48 are examples of a chromate treatment liquid containing chromic acid, a chromic acid reduction product, and phosphoric acid, and it is a liquid in which uniform coating is considerably difficult. In the case of hot air method,
The yellow tint becomes stronger than that dried by I.H., and the uneven processing after drying is noticeable. By drying at I.H., the yellow tint becomes lighter and the appearance becomes fairly uniform, but there are variations in lightness that are thought to be caused by coating unevenness, and some unevenness remains.

【００５７】Ｎo.49、50は、クロム酸に対するクロム酸
還元生成物の比率を高めた例であるが、処理液のクロム
酸還元性生物を増やしてもＮo.47、48の結果と同じであ
り、熱風乾燥で乾燥するかぎり大きな効果は得られてい
ない。Nos. 49 and 50 are examples in which the ratio of the chromic acid reduction product to chromic acid was increased, but the results are the same as Nos. 47 and 48 even if the chromic acid reducing products in the treatment liquid are increased. However, as long as it is dried by hot air drying, no great effect is obtained.

【００５８】Ｎo.51、52は、乾燥条件を変えた例であ
る。いずれにおいても、熱風乾燥においては、乾燥到達
板温を高くしても黄色味を薄くする効果が得られず、し
たがって外観も向上していない。また、熱風乾燥を行っ
た後にＩ.Ｈ.により加熱しても外観は向上しない(Ｎo.5
5）。一方、Ｉ.Ｈ.の場合には、110℃でもすでに黄色味
が薄くなり、それ以上板温を高くしても色調が安定して
いる（Ｎo.53）。また、Ｉ.Ｈ.の炉内雰囲気温度を200
℃としても色調には影響せず（Ｎo.54）、Ｉ.Ｈ.による
乾燥後に熱風乾燥を行っても色調は変化していない（Ｎ
o.56）。炉内雰囲気温度を200℃としてもＩ.Ｈ.で加熱
を行わないと明らかに濡れた状態のままであり、この条
件では乾燥はＩ.Ｈ.による加熱によって主に生じている
ことが黄色味が薄くなる原因と考えられる。Nos. 51 and 52 are examples in which the drying conditions are changed. In any case, in hot air drying, the effect of reducing the yellowish tint is not obtained even if the temperature of the plate to be dried is increased, and therefore the appearance is not improved. Also, the appearance is not improved by heating with I.H. after drying with hot air (No. 5
Five). On the other hand, in the case of I.H., the yellow tint has already become thin even at 110 ° C., and the color tone is stable even if the plate temperature is further raised (No. 53). In addition, the ambient temperature of the I.H.
Even if the temperature is set to ℃, it does not affect the color tone (No. 54), and the color tone does not change even after hot air drying after drying by I.H.
o.56). Even if the atmosphere temperature in the furnace is set to 200 ° C., it is clearly wet unless I.H. is heated. Under these conditions, the drying is mainly caused by the heating by I.H. Is thought to be the cause of thinning.

【００５９】Ｎo.57、58は、有機高分子を含んだクロメ
ート処理液の例であるが、有機高分子の添加により塗布
は均一に行えるが、乾燥後の外観はこれまでの結果同様
にＩ.Ｈ.の方が優れている。Nos. 57 and 58 are examples of the chromate treatment liquid containing an organic polymer, and the coating can be performed uniformly by adding the organic polymer, but the appearance after drying is similar to the results so far. .H. Is better.

【００６０】Ｎo.59、60は溶融亜鉛めっき鋼板に処理し
た場合の例であるが、これまでの結果同様にＩ.Ｈ.の方
が黄色味が薄くなり、外観の均一性に優れている。Nos. 59 and 60 are examples of the case where hot-dip galvanized steel sheets are treated. As in the results so far, I.H. has a lighter yellow tint and is superior in uniformity of appearance. .

【００６１】上記実施例で得られた結果を図１〜４に示
す。図１〜３中、○は耐食性を示し、●は耐黒点錆性を
示している。The results obtained in the above examples are shown in FIGS. In FIGS. 1 to 3, ◯ indicates corrosion resistance, and ● indicates black spot rust resistance.

【００６２】[0062]

【発明の効果】以上のようにこの発明によれば、亜鉛め
っき鋼板の表面にクロム酸(Ｃr6+）、クロム酸還元生成
物、及び平均粒子径10ｍμ以下のコロイダルシリカを主
成分とし、クロム酸とクロム酸還元生成物との混合比が
各々ＣrＯ3換算での重量比で１：0.3〜0.55、クロム酸
とクロム酸還元生成物との合計量とシリカとの混合比が
クロム酸とクロム酸還元生成物との合計量はＣrＯ3換算
での重量比で、シリカはＳiＯ2換算での重量比で1：1.5
〜2.5の比率で、かつクロム酸濃度がＣr6+として４ｇ／
ｌ以上、シリカ濃度がＳiＯ2換算で20ｇ／ｌ以上の範囲
内にあるクロメート処理液を塗布し、水洗することなく
最高到達板温105℃以上で乾燥することにより、亜鉛め
っき鋼板表面に、クロム酸及びクロム酸還元生成物を含
む処理液を塗布した後、水洗することなく濡れた状態で
誘導加熱により板温を上昇させることにより乾燥するこ
とにより、外観均一性、難溶性、耐黒点錆性、皮膜経時
安定性、塗布性、耐食性等に優れたクロメート処理亜鉛
めっき鋼板を安定して製造できる効果がある。As described above, according to the present invention, chromic acid (Cr 6+ ), a chromic acid reduction product, and colloidal silica having an average particle diameter of 10 mμ or less are used as main components on the surface of a galvanized steel sheet, and chromium is contained. The mixing ratio of the acid and the chromic acid reduction product is 1: 0.3 to 0.55 in weight ratio in terms of CrO 3, respectively, and the mixing ratio of the total amount of chromic acid and the chromic acid reduction product and silica is chromic acid and chromium. The total amount with the acid reduction product is a weight ratio in terms of CrO 3 , and silica is 1: 1.5 in a weight ratio in terms of SiO 2.
At a ratio of up to 2.5 and a chromic acid concentration of Cr 6+ of 4 g /
1 or more and a silica concentration in the range of 20 g / l or more in terms of SiO 2 is applied and dried without washing with water at a maximum reaching plate temperature of 105 ° C. After applying a treatment liquid containing acid and chromic acid reduction products, drying by increasing the plate temperature by induction heating in a wet state without washing with water, uniformity of appearance, poor solubility, black spot rust resistance In addition, there is an effect that a chromate-treated galvanized steel sheet having excellent film temporal stability, coatability, corrosion resistance, etc. can be stably manufactured.

【図面の簡単な説明】[Brief description of drawings]

【図１】 Ｃｒ還元率と耐食性、耐黒点錆性の関係の例
を示すグラフである。FIG. 1 is a graph showing an example of a relationship between a Cr reduction rate and corrosion resistance and black spot rust resistance.

【図２】 シリカ粒子径と耐食性、耐黒点錆性の関係の
例を示すグラフである。FIG. 2 is a graph showing an example of the relationship between silica particle size, corrosion resistance, and black spot rust resistance.

【図３】 乾燥板温と経時後耐食性、耐黒点錆性の関係
の例を示すグラフである。FIG. 3 is a graph showing an example of the relationship between the dry plate temperature, corrosion resistance after aging, and black spot rust resistance.

【図４】 クロメート処理液中に添加したＺｎ化合物
（ＺｎＯ）をＺｎ換算した値とロールコーターで塗布し
た場合の単位面積当りから処理液中に混入するＺｎ量の
関係を示すグラフである。FIG. 4 is a graph showing a relationship between a Zn-converted value of a Zn compound (ZnO) added to a chromate treatment liquid and the amount of Zn mixed in the treatment liquid per unit area when coated with a roll coater.

Claims (3)

【特許請求の範囲】[Claims] 【請求項１】 亜鉛めっき鋼板の表面に、クロム酸、ク
ロム酸還元生成物、及び平均粒子径10ｍμ以下のコロイ
ダルシリカを主成分とし、クロム酸とクロム酸還元生成
物との混合比が各々ＣrＯ3換算での重量比で1：0.3〜0.
55、クロム酸とクロム酸還元生成物とのＣrＯ3換算での
合計量とＳiＯ2換算でのシリカとの混合比が重量比で
1：1.5〜2.5、かつクロム酸濃度がＣr6+として４ｇ／ｌ
以上、シリカ濃度がＳiＯ2換算で20ｇ／ｌ以上の範囲内
にあるクロメート処理液を塗布し、最高到達板温105℃
以上で乾燥することを特徴とする、クロメート処理亜鉛
めっき鋼板の製造方法1. The surface of a galvanized steel sheet is mainly composed of chromic acid, a chromic acid reduction product, and colloidal silica having an average particle size of 10 mμ or less, and the mixing ratio of chromic acid and the chromic acid reduction product is CrO. Weight ratio in terms of 3 is 1: 0.3 to 0.
55. The mixing ratio of the total amount of chromic acid and a chromic acid reduction product in terms of CrO 3 and silica in terms of SiO 2 is a weight ratio.
1: 1.5 to 2.5 and chromic acid concentration of Cr 6+ is 4g / l
As described above, the chromate treatment liquid having a silica concentration in the range of 20 g / l or more in terms of SiO 2 was applied, and the maximum plate temperature reached 105 °
A method for producing a chromate-treated galvanized steel sheet characterized by being dried as described above 【請求項２】 クロメート処理液がＺｎ化合物をさらに
含み、Ｃr6+とＺｎとの混合比が重量比で1：0.06〜0.3
であるかあるいはクロメート処理液のｐＨが2.3〜3.0で
あることを特徴とする請求項１記載のクロメート処理亜
鉛めっき鋼板の製造方法2. The chromate treatment liquid further contains a Zn compound, and the mixing ratio of Cr 6+ and Zn is 1: 0.06 to 0.3 by weight.
Or the pH of the chromate treatment liquid is 2.3 to 3.0. The method for producing a chromate-treated galvanized steel sheet according to claim 1, wherein 【請求項３】 亜鉛めっき鋼板表面に、クロム酸及びク
ロム酸還元生成物を含む処理液を塗布した後、濡れた状
態で誘導加熱により板温を上昇させることにより乾燥す
ることを特徴とするクロメート処理亜鉛めっき鋼板の製
造方法3. A chromate characterized by applying a treatment liquid containing chromic acid and a chromic acid reduction product to the surface of a galvanized steel sheet and then drying it by increasing the plate temperature by induction heating in a wet state. Method for producing treated galvanized steel sheet
JP23832593A 1992-09-24 1993-09-24 Manufacturing method of chromate treated galvanized steel sheet Expired - Fee Related JP3286959B2 (en)

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JP23832593A JP3286959B2 (en) 1992-09-24 1993-09-24 Manufacturing method of chromate treated galvanized steel sheet

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JP4-254284 1992-09-24
JP25428492 1992-09-24
JP23832593A JP3286959B2 (en) 1992-09-24 1993-09-24 Manufacturing method of chromate treated galvanized steel sheet

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JP3286959B2 JP3286959B2 (en) 2002-05-27

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2021143382A (en) * 2020-03-12 2021-09-24 Ｊｆｅスチール株式会社 Magnetic steel sheet with insulating coating, and manufacturing method thereof

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2021143382A (en) * 2020-03-12 2021-09-24 Ｊｆｅスチール株式会社 Magnetic steel sheet with insulating coating, and manufacturing method thereof

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