Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
1999-04-14
2002-05-14
Copenheaver, Blaine (Department: 1773)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S328400, C428S328000, C428S461000, C428S463000
Reexamination Certificate
active
06388021
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an acrylic resin-containing metal surface treatment composition, treatment method and treated metal material, and in particular to an acrylic resin-containing metal surface treatment composition, treatment method and treated metal material giving improved corrosion resistance, film adhesion and slip properties (referred to also as “lubricity”).
BACKGROUND OF THE INVENTION
Conventionally, phosphate treatment, chromate treatment and non-chromate treatment, etc. were performed as surface treatments for food cans, car bodies, coil coatings for steel plate and metals for construction materials. For example, a phosphate film is formed on a metal surface as a pretreatment when organic coatings such as paints and adhesives are applied to metal surfaces such as iron, zinc, and aluminum. By subsequently applying an organic film such as a coating, corrosion resistance and film adhesion can be improved. However, conventional phosphate treatment did not necessarily provide sufficient corrosion resistance, film adhesion or slip properties to satisfy demand in recent years.
To improve corrosion resistance following phosphate treatment, it was common to apply a coating after first applying a primer coat. However, if a primer was first applied, although corrosion resistance and film adhesion improved, the number of coating steps increased, complicating the procedure and leading to higher cost.
“A Metal Surface Treatment for Composite Films” of Japanese Patent Laid-open publication No. Hei 5-117869 was proposed for example as a metal surface treatment which aims to omit the primer coating while giving highly developed corrosion resistance and film adhesion. The metal surface treatment of the aforesaid Japanese Patent Laid-open publication No. Hei 5-117869 is a phosphate surface treatment liquid comprising a cationic organic polymer compound or one of its salts having one or more cationic nitrogen atoms, and a molecular weight in the range of 1,000-1,000,000.
In the “Surface Treatment Method for Aluminum and Aluminum Alloys” described in Japanese Laid-open publication No. Sho 51-73938, the metal to be treated is limited to aluminum. This method aims to confer corrosion resistance and film adhesion properties. It is described that this metal surface treatment method uses a liquid of which the principal components are water-soluble resins such as vinyl acetate, vinylidene chloride and acrylic acid or organic polymer film forming substances comprising emulsion resins, and a water-soluble titanium compound.
However, although they offer improved corrosion resistance and film adhesion compared with the prior art, neither the aforesaid metal surface treatment agent nor treatment method has reached recent demand requirements. In particular, in the manufacture of food cans using aluminum or its alloys, they do not prevent jamming, and in the coil coating of steel plate, lubricity is poor.
DISCLOSURE OF THE INVENTION
It is therefore an object of this invention to provide an acrylic resin-containing metal surface treatment composition, treatment method and treated metal material offering improved corrosion resistance, film adhesion and slip properties.
To achieve this object, the acrylic resin-containing metal surface treatment composition according to this invention comprise:
a) a water-soluble, water-dispersible or emulsifiable acrylic resin comprising either an amino group or an ammonium group, or both, together with a hydroxyl group and hydrophobic group, and
b) a heavy metal or one of its salts.
As permeability is suppressed by an inorganic film which comprises a heavy metal or one of its salts, corrosion resistance improves. Further, as the amino group or ammonium group in the acrylic resin is coordinated with the (heavy) metal, the aforesaid inorganic film is connected via the acrylic resin. This prevents cohesive failure of the inorganic film, giving an almost uniform substrate film on the metal surface which improves adhesion between the substrate film and the topcoat. The substrate film of this invention refers to the film formed on the metal surface which comprises the aforesaid inorganic film connected by the acrylic resin. In addition, the aforesaid acrylic resin is almost uniformly distributed on the substrate film surface, so frictional resistance is reduced and slip properties are improved.
Preferably, the amino group or the ammonium group in the acrylic resin-containing metal surface treatment composition according to this invention comprises at least the structural unit represented by the following chemical formulae (I) or (II).
where R
1
, R
2
are hydrogen, hydroxyl, a substituted or unsubstituted straight chain or branched alkyl group comprising 1-5 carbon atoms, or a substituted or unsubstituted straight chain or branched hydroxyalkyl group comprising 1-5 carbon atoms
where R
3
, R
4
, R
5
are hydrogen, hydroxyl, a substituted or unsubstituted straight chain or branched alkyl group comprising 1-5 carbon atoms, or a substituted or unsubstituted straight chain or branched hydroxyalkyl group comprising 1-5 carbon atoms.
Moreover, the molecular weight of the acrylic resin in this invention is 500-100,000, and preferably 1,000-20,000. When the molecular weight is less than 500, corrosion resistance decreases. On the other hand, when the molecular weight exceeds 100,000, hydrophilic properties decrease.
According to this invention, the acrylic resin content is 0.01-10 g/l and preferably 0.1-5 g/l relative to the metal surface treatment composition. When the acrylic resin content is less than 0.1 g/l, a binder effect is not manifested, and the physical durability of the substrate film decreases. On the other hand, when the acrylic resin content exceeds 10 g/l, the adhesion between the substrate film and the metal surface decreases.
In the acrylic resin-containing metal surface treatment composition according to this invention, the acrylic resin contains 1-10 amino and/or ammonium groups, 1-10 hydroxyl groups and 1-5 hydrophobic groups per 1000 molecular weight units of acrylic resin. When there is less than one amino or ammonium group per 1000 molecular weight units of acrylic resin, hydrophilic properties and adhesion to the metal decrease. On the other hand, when there are more than 10 amino or ammonium groups per 1000 molecular weight units of acrylic resin, corrosion resistance decreases.
When there is less than one hydroxyl group per 1000 molecular weight units of acrylic resin, hydrophilic properties and film adhesion decrease. On the other hand, when there are more than 10 hydroxyl groups per 1000 molecular weight units of acrylic resin, corrosion resistance decreases.
When there is less than one hydrophobic group per 1000 molecular weight units of acrylic resin, corrosion resistance and slip properties decrease. On the other hand, when there are more than 5 hydrophobic groups per 1000 molecular weight units of acrylic resin, hydrophilic properties and film adhesion decrease.
In the acrylic resin-containing metal surface treatment composition, the amino group or ammonium group contained in the acrylic resin is introduced by copolymerization of a monomer comprising at least the structural unit represented by the following chemical formulae (III) or (IV):
where R
6
is hydrogen or methyl, R
7
, R
8
are hydrogen, hydroxyl, a substituted or unsubstituted straight chain or branched alkyl group comprising 1-5 carbon atoms, or a substituted or unsubstituted straight chain or branched hydroxyalkyl group comprising 1-5 carbon atoms, and R
9
is an alkylene group comprising 1-5 carbon atoms.
where R
10
are hydrogen or methyl, R
11
, R
12
are hydrogen, hydroxyl, a substituted or unsubstituted straight chain or branched alkyl group comprising 1-5 carbon atoms, or a substituted or unsubstituted straight chain or branched hydroxyalkyl group comprising 1-5 carbon atoms, and R
13
is an alkylene group comprising 1-5 carbon atoms.
In the acrylic resin-containing metal surface treatment composition according to this invention, the hydroxyl group
Kanda Tomoyuki
Maekawa Susumu
Shibata Yasuhiro
Tounaka Atsuhiko
Yasuhara Kiyotada
Copenheaver Blaine
Kruer Kevin
Nippon Paint Co. Ltd.
Oliff & Berridg,e PLC
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