JPS6230832B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for treating metal surfaces, and in particular, by treating the metal surface with a mixture of different types of organic silane compounds, it is possible to prevent rust on the metal surface and improve adhesiveness and secondary adhesion with resin. This article relates to a metal surface treatment method that is excellent in surface treatment. Conventionally, metals have been widely coated with synthetic resins for purposes such as corrosion resistance and electrical insulation. For example, polyolefins have strong corrosion resistance against acids, alkalis, and certain organic solvents, and are also used in steel pipes, steel plates, drums, etc. due to their excellent electrical insulation properties and ease of coating work.
It is widely used for covering electric wires, machinery and equipment, and for laminated with metal plates. As a method to improve the adhesion between these metal surfaces and the polyolefin layer, polyolefins are modified by, for example, blending unsaturated carboxylic acids or derivatives thereof into the polyolefins, or graft polymerizing these monomers. ing. It is also known to treat metal surfaces with acids or primers. However, although this modified polyolefin or a metal surface coating or a laminate with a metal plate using this modified polyolefin as an adhesive has high adhesion, the adhesive joint has low water resistance and salt water resistance, and water from scratches in the coating layer does not easily escape. There were problems with durability such as infiltration and cathodic electrolysis removability, so-called secondary adhesion. In order to improve these problems, for example, in the method of coating metal pipes with polyethylene via a polyolefin adhesive modified with maleic anhydride, the metal pipes are pretreated with a chromic acid-based or phosphoric acid-based conversion coating. A method has been proposed to apply
-113871). However, although the chromic acid treatment in this method improves secondary adhesion, it uses toxic hexavalent chromium, which poses safety and health problems. On the other hand, although phosphoric acid treatment is simple and has an antirust effect, it cannot be said that the secondary adhesion is necessarily sufficient. The present invention was made for the purpose of improving such drawbacks in conventionally known coatings of metals with resins or laminates of metals and resins.
The metal surface treatment method of the present invention includes treating the metal surface with the general formula R ¹ _n Si (OR ² ) _4-n ...(1) [where R ¹ is a substituted alkyl substituted with a polar group, a substituted cycloalkyl group, or a substituted substituted cycloalkyl group] Aryl, R ²
represents alkyl or aryl which may have a substituent, m = 1 or 2, and a hydrophilic organic silane compound represented by the general formula R ³ _o Si (OR ⁴ ) _4-o ...(2) [However, , R ³ is alkyl, vinyl, aryl or cycloalkyl which may have a substituent, R ⁴ is alkyl or aryl which may have a substituent, and n=1 or 2] This is a metal surface treatment method characterized by treatment with a mixture with a hydrophilic organic silane compound. Examples of metals that can be treated with the organosilane compound in the present invention include aluminum, iron, copper,
These include tin, zinc, nickel, etc., and alloys containing one or more of these, such as stainless steel. Among these, iron and aluminum are preferred. Furthermore, the present invention can be applied to metal molded products in various shapes such as tubes, plates, foils, rods, wires, and others. In addition, the hydrophilic organosilane compound represented by the general formula R ¹ _n Si (OR ² ) _4-n (1) in the present invention includes:
R ¹ is nitrogen, oxygen, sulfur, which has an affinity for unsaturated carboxylic acids, their acid anhydrides, or their esters;
Examples include alkyl, cycloalkyl, or aryl substituted with a polar group containing an element such as phosphorus, where R ² is alkyl or aryl which may have a substituent, and m=1 or 2. Among these, those where m=1 are particularly preferred.
Examples of the above polar group include amino, ureido, glycidoquine, epoxy, mercapto, methacryloquine, and anilino group, and examples of the above substituent include methoxy group. Specific examples of R ¹ include γ-aminopropyl, N-β-(aminoethyl)-γ-aminopropyl, γ-ureidopropyl, γ-glycidoxypropyl, β-(3,4-epoxy cyclohexyl)ethyl, para-aminophenyl, γ-mercaptopropyl, γ-anilinopropyl, N-
Examples include β-(N-vinylbenzylaminoethyl)-γ-aminopropyl. Further, specific examples of ^R2 include methyl, ethyl, propyl, butyl, β-methoxyethyl, and phenyl. Among these hydrophilic organosilane compounds, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane , γ-anilinopropyltrimethoxysilane, N-β-(N-vinylbenzylaminoethyl)-γ-aminopropylmethoxysilane, and the like are preferred. The non-hydrophilic organosilane compound represented by the general formula R ³ _o Si (OR ⁴ ) _4-o (2) in the present invention includes:
Alkyl, vinyl, where R ³ may have a substituent,
Examples include aryl or cycloalkyl, in which R ⁴ has alkyl or aryl which may have a substituent, and n=1 or 2. Specific examples of R ³ include methyl,
Examples include ethyl, propyl, butyl, vinyl, cyclohexyl, phenyl, octadecyl, and γ-methacryloxypropyl. Specific examples of R ⁴ include methyl, ethyl, propyl, butyl, β-methoxyethyl, and phenyl. Among these non-hydrophilic organic silane compounds, vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, cyclohexyltriethoxysilane and the like are preferred. The mixing ratio of the hydrophilic organosilane compound (1) and the non-hydrophilic organosilane compound (2) in the present invention is the hydrophilic organosilane compound (1)...(a) and the non-hydrophilic organosilane compound (2)... (b) and (a)/(a+b)×100=
It ranges from 95 to 20, preferably from 90 to 50. If the ratio of the hydrophilic organic silane compound (1) exceeds 95, the secondary adhesion will decrease, while if it is less than 20, the adhesive strength will decrease, both of which are not preferred. Note that two or more types of organic silane compounds (1) and (2) may be mixed as long as the mixing ratio is within the above range. The treatment method using an organic silane compound includes water or a solvent that can be mixed with water, such as methanol, ethanol, propanol, t-butanol, acetone,
For methyl ethyl ketone, methyl cellosolve, etc.
Dissolve 0.05-10% by weight, preferably 0.1-2% by weight to form a homogeneous solution. Preparation of the mixed solution is not particularly limited, and may be performed by mixing and then dissolving, or by dissolving separately and then mixing. Alternatively, it may be dissolved and then heated, or it may be dissolved in a heated solvent. Examples of methods include applying this uniform solution to a descaled metal surface at room temperature to 100°C, preferably room temperature to 80°C, or immersing the metal surface in the solution. Application methods include gravure roll, air spray, spray, roll coater, brush, etc., but for continuous treatment, gravure roll, air spray, roll coater, dipping, etc. are preferred. The metal surface coated in this way is heated to a temperature of 60 to 250°C using a heater such as a hot air dryer or an induction heater.
Preferably, it is heated and dried at 80 to 200° C. for 2 seconds to 10 minutes, preferably 10 seconds to 5 minutes to remove the solvent and at the same time perform silanol condensation to form a polysiloxane film. If the concentration of the organosilane compound is less than 0.05% by weight, the effects of the present invention cannot be expected, while if it exceeds 10% by weight, dissolution will be insufficient and both are not preferred. If the temperature of the solution is outside the above range, if it is too low, the organic silane compound will not be sufficiently dissolved, and if it is too high, the solvent will evaporate rapidly, resulting in poor workability. Further, if the drying temperature is lower than 60°C, the solvent will not be removed sufficiently and the polycycloxane film will not be formed sufficiently, which is not preferable. Next, an embodiment of the method for treating a metal surface according to the present invention will be described in detail using a method for manufacturing a resin-coated metal tube as an example. The base metal steel pipe is cleaned by surface treatment such as shot blasting, grit blasting, or pickling, or by chemical conversion treatment such as zinc phosphate.
After being immersed in the solution of the mixed organic silane compound, the metal tube is taken out and heated to dry. Then,
The metal tube on which the silane coating has been formed is coated with a polyolefin adhesive by extrusion coating or sheet-like wrapping, and then the exterior resin is further extruded or wrapped in sheet-form to form a laminated coating. . The polyolefin-based adhesive and sheathing material may be extruded and coated in multiple layers on the silane-treated metal tube, or may be laminated and coated by wrapping a composite sheet around the tube. Furthermore, the resin coating of the exterior material may be omitted as appropriate depending on the application. As the above-mentioned polyolefin adhesive, a copolymer obtained by reacting an olefin, a polyolefin, or a hydrocarbon elastomer with an unsaturated carboxylic acid or a derivative thereof, or a grafted modified product can be used. Examples of the polyolefin include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, and 4-methyl-1-pentene. As the polyolefin, for example, a homopolymer of the above olefin or one of the above monomers and 10
Examples include copolymers with other α-olefins or vinyl acetate with a crystallinity of 20% or more (X-ray diffraction method) or mixtures thereof, but among these, medium-low density Polyethylene, polypropylene, etc. are preferred. Examples of the hydrocarbon elastomer include ethylene-propylene rubber, ethylene-1-butene rubber, ethylene-propylene-dien tapolymer,
Examples include polyisobutylene rubber, ethylene-butadiene rubber, butadiene rubber, styrene-butadiene rubber, among which ethylene-propylene rubber, ethylene-1-butene rubber,
Polyisobutylene rubber and the like are preferred. As unsaturated carboxylic acids or derivatives thereof,
For example, acrylic acid, methacrylic acid, fumaric acid, maleic acid, citraconic acid, itaconic acid, endo-
Bicyclo[2,2,1]-1,4,5,6,7,
7-hexachloro-5-heptene-2,3-dicarboxylic acid, endo-bicyclo[2,2,1]-5
-Heptene-2,3-dicarboxylic acid, cis-4-
Examples include cyclohexene-1,2 dicarboxylic acid, and acid anhydrides or esters thereof. Among these are maleic anhydride, endo-
Bicyclo-[2,2,1]-5-heptene-2,3
-Dicarboxylic anhydride and the like are preferred. Various known methods can be employed for the reaction of the above-mentioned olefin, polyolefin, or hydrocarbon elastomer with the unsaturated carboxylic acid or its derivative. Further, the polyolefin or the hydrocarbon elastomer may be used alone or in combination. Furthermore, the obtained copolymer or graft modified product may be used after being diluted with a polyolefin and/or a hydrocarbon elastomer. The resin for the above-mentioned exterior material is not limited as long as it has an affinity with the above-mentioned polyolefin-based adhesive, and can be selected as appropriate depending on the application. Examples include polyolefin, polyurethane, polyamide, polyester, etc. Among these, polyolefins are preferred, and polyethylene is particularly preferred. As described above, the method of the present invention is applicable not only to coating the outer surface of metal tubes, but also to resin coating the inner surface of tubes, metal surfaces of various shapes such as plate foils, rods, and wires, and laminates of metal and resin.
It can also be applied to painting and printing on metal. In addition, by applying the organic silane compound treatment of the present invention, rust is prevented during the process from descaling the metal surface to the resin coating process, and it also improves the adhesive strength in the metal and coating resin, and the metal and resin laminate. Next, adhesion can be enhanced. Hereinafter, the method of the present invention will be explained in more detail using Examples. In addition, % in the examples indicates weight, and the test method is as follows. (1) Melt index (MI) JIS K 6760 (2) Melt flow index (MFI) JIS K
6758 (3) Adhesive strength In the case of coated metal surface pipes, the resin layer was cut into strips with a width of 1 cm, the adhesive layer was peeled off from one end, and a 90° peel test was performed at a speed of 5 cm/min. In addition, in the case of a laminate, the laminate should be 25mm x
It was cut into a 300 mm strip, the end face was peeled off by 50 mm to provide a gripping margin, a 90° peel test was performed at a speed of 10 cm/min, and the adhesive strength was divided by 2.5 to calculate the adhesive strength per 1 cm width. (4) Salt water immersion: 80℃ for coated metal surface pipes,
The degree of peeling of the coating was examined after 100 hours of immersion in a 3% NaCl solution. Also, for laminates, 50
A mm x 200 mm test piece was immersed in a 3% NaCl solution at 60°C, and the degree of penetration was examined from the end face after 30 days. (5) Cathodic electrolysis removability ASTM G-8-72 compliant,
5mmφ, holiday, applied voltage 1.5V, 20℃/30
day, in 3% NaCl solution. (6) Rust prevention The pickled and organic silane treated samples were observed for rust after 5 days, and no rust was rated as ○, while rust was rated as ×. (7) Heat cycle test A 25m x 300mm laminate was used as a test piece, and the test piece was placed in a -30℃ thermostatic chamber for 8 hours.
time, then set in a constant temperature bath at 60℃ for 16 hours,
This was considered as one cycle. The adhesive strength of the test piece was measured after the same cycle was repeated 10 times. (8) Post-workability (bending) A 25 mm x 200 mm laminate was used as a test piece, and this test piece was wound around the circumference of a 6 mmφ steel bar and bent to a radius of 3 mmφ. The bent portion was cut and the state of peeling was observed. (9) Adhesive strength after rusting test After treating the metal pipe with an organic silane compound, it was tested at 60℃ and 90%RH for 14 hours.
After being kept for 1 day, the adhesive strength of the resin-coated products was measured. Examples 1 to 8 A 50 mmφ SGP black tube was descaled by pickling as a test metal tube, and then 1% of a mixture of organic silane compound (1) and organic silane compound (2) as shown in Table 1 was added. The surface of the metal tube was immersed in a mixed solution at a temperature of 80°C and dried at a temperature of 100°C. The material was coated by extrusion at a temperature of 120° C. to a thickness of 0.4 mm, and then high-density polyethylene (density = 0.935 g/cc, MI = 0.2 g/10 min) was laminated and coated to a thickness of 3 mm. The obtained resin-coated metal tube was tested for adhesive strength, adhesive strength after rust prevention test, saline immersion, and cathodic electrolytic releasability, and the results are shown in Table 1. In addition, regarding rust prevention properties, comparisons were made between those after pickling and those after silane treatment. Comparative Examples 1 to 3 In Examples, those treated with an organic silane compound alone, those treated with only pickling, and those treated with zinc phosphate instead of the organic silane compound were similarly coated with resin, and the results were Table-1
Also listed.

[Table] Example 9 Using the continuous laminate manufacturing equipment shown in Fig. 1, a cold rolled steel plate (thickness 0.2 mm, width 300 mm) 1 is used, and on the surface of each layer, γ-aminopropyltriethoxysilane [organosilane compound (1)] with a concentration of 0.8% and vinyltrimethoxysilane [organosilane with a concentration of 0.2%] are used. A mixed aqueous solution of an organic silane compound containing compound (2)] was taken up using a roll coater 6 at a speed of 5.
The coating was applied at a rate of m/min and dried in a steel plate preheating drying device 9 with an outlet temperature of 100°C. Next, modified polyethylene [linear low-density polyethylene (MI = 2.0 g / 10 minutes, density = 0.926
g/cc, hereinafter L-LDPE-1) 80 parts and ethylene-
1-Butene rubber (MI4.0g/10 minutes, density 0.88g/
cc, hereafter EBR) 0.6 parts of maleic anhydride in a mixture of 20 parts
% grafted modified product, L-LDPE-1
Sheet 2 of the composition consisting of 60 parts of EBR and 15 parts of EBR was extruded from an extruder 11 with a diameter of 65 mm at a temperature of 230°C.
The laminated plate 16 was manufactured by extruding it with a roll 13 at a set temperature of 180° C. and a set pressure of 1.0 Kg/cm ² . The thickness composition of the obtained laminate was 0.2 mm/0.4 mm/0.2 mm of steel plate/modified polyethylene/steel plate. The obtained laminate was tested for adhesive strength, saline immersion, heat cycle test, and post-processability (bending), and the results are shown in Table 2. Examples 10 to 12 In Example 9, instead of the mixed aqueous solution containing γ-aminopropyltriethoxysilane with a concentration of 0.8% and vinyltrimethoxysilane with a concentration of 0.2%,
Laminated plates were produced in the same manner except that a mixed solution of organic silane compounds as shown in Table 2 was used, and the test results are also listed in Table 2. Comparative Examples 4 to 6 In Example 9, the organosilane compound was not pretreated. Instead of the organosilane compound, the organosilane compound was treated with zinc phosphate in advance by a conventional method, and the steel plate preheating drying device outlet temperature was set at 130°C. Preheat temperature to 120℃
A laminate was produced in the same manner, except that it was treated with γ-aminopropyltriethoxysilane alone at a concentration of 1%, and the test results are also listed in Table 2.

【table】 [Brief explanation of the drawing]

FIG. 1 is a schematic side view of a continuous laminate manufacturing apparatus showing an embodiment of the present invention. 1... Metal sheet, 2... Modified polyolefin, 3
...Uncoiler, 4...Take-up roll, 5...Guide roll, 6...Surface coating device, 7...Doctor knife, 8...Surface coating liquid and container, 9...Preheating drying device, 10...Guide roll, 11...Extruder, 12
... T-die, 13... Heat pressure bonding roll, 14... Preheating device, 15... Cooling device, 16... Laminate plate.

Claims (1)

[Claims] 1 The metal surface is formed by the general formula R ¹ _n Si (OR ² ) _4-n ...(1) [However, R ¹ is alkyl, cycloalkyl or aryl substituted with a polar group, and R ² is a substituent. represents an alkyl or aryl which may have m=
1 or 2] and the general formula R ³ _o Si(OR ⁴ ) _4-o ...(2) [However, R ³ is an alkyl or vinyl compound which may have a substituent. , aryl or cycloalkyl, R ⁴ represents alkyl or aryl which may have a substituent, and n = 1 or 2]. A method for treating metal surfaces.