JPS6248543A - Manufacture of composite laminated steel plate having excellent moldability and corrosion resistance - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for manufacturing a composite laminated steel plate with good formability, and in particular, strengthens the adhesive force between the steel plate and resin, and reduces the amount of iron exposed on the end face of the steel plate. This invention relates to a method for producing a composite single-layer steel plate which has enhanced corrosion resistance and has good II4' corrosion resistance over a long period of time.

<Prior art and its problems> H1-layer steel plates, in which thermoplastic resin is sandwiched between steel plates, can be divided into two types. One is a composite laminated steel plate in which the proportion of the steel plate is larger than that of the resin and has an excellent vibration damping effect. On the other hand, an extremely thin steel plate is used for the surface layer to ensure strength, and the middle layer is made of a thick and lightweight resin called light steel plate. When both are used in automatic medium phase materials and construction materials,
Excellent: It has the advantages of vibration resistance and weight reduction, but because the intermediate layer is sandwiched with a resin that has a completely different deformation behavior than that of steel, its formability is generally inferior to that of a single steel plate. There's a problem.

In order to improve formability, it is necessary to strengthen the bond between the resin and the steel plate. For this reason, by applying chromate treatment to the steel plate, the polar groups in the resin (=(Sho, -( Attempts have been made to strengthen the bond at the interface between the resin and the steel plate by forming a highly reactive Eiwa chromium oxide layer (Cr-Oll) with h' during the production of the layered steel plate. There is.

Specifically, Japanese Patent Laid-Open No. 58-90952 discloses an attempt to prevent adhesive deterioration of a laminate due to salt water or the like by electrolytic chromate treatment.

In addition, the present applicant has proposed that a small amount of Cr6+ be present through coating type 11 chromate treatment to passivate Fe in a corrosive environment to prevent deterioration of the contact area of the laminate (i1r). (Gan Sho 59-245662).

However, among these chromate treatments, electrolytic chromate treatment is difficult to complete on one side, and the chromium oxide on the side that does not adhere to the resin hardens the surface, resulting in poor lubricity and poor formability. It is. Also coating with chromium oxide! I77111 chromate treatment has the advantage of being easy to treat on one side and ensuring an appropriate amount of chromium, but there are problems with corrosion resistance due to red rust entering from the edge of the steel plate.
In particular, secondary adhesion is poor due to deterioration over time in adverse environments.
There is a drawback that moldability decreases.

As mentioned in 1 above, composite laminates have various problems because the intermediate layer is a resin that has completely different deformation behavior from C steel sheets, and it is desirable to improve the molded Pt and corrosion resistance. It's over.

<Objective 1 of the Invention> The purpose of undeveloped 11111 is to solve the problems of the prior art as described in (1), strengthen the adhesive force between the steel plate and the resin, strengthen the corrosion resistance of the exposed iron part of the steel plate end face, and provide long-term protection. Improved corrosion resistance and formability! ,: An object of the present invention is to provide a method for manufacturing a composite laminated steel plate.

<Structure of the Invention> Fig. 1 does not show a composite laminated steel plate manufactured by the manufacturing method of the present invention. The present invention is a method for producing a composite laminated steel sheet in which the chromate-treated blood of a steel sheet 1 having a chromate-treated layer 2 is used as the resin side, and an intermediate layer (polyolefin thermoplastic resin 3) is sandwiched between the two. Those with a low lamination ratio of resin 3 are called vibration damping steel plates, and those with a high lamination ratio are called light-damping steel plates.
1 steel plate, or rather, the composite J11-layer steel plate manufactured by the manufacturing method of the present invention includes a J-shape steel plate and a light [11 steel plate].

Composite laminated steel sheets have resin as an intermediate layer that has completely different deformation behavior than steel sheets, so it is difficult to form them.
As described above, this tendency is particularly noticeable in lightweight steel plates whose thickness is around 0.2 m+n, which is extremely thin.

Therefore, in order to ensure formability as a composite 61-layer steel plate, it is necessary to strengthen the adhesive force between the steel plate and the resin so that the resin deforms as the steel plate deforms. In addition, when the adhesive strength between the steel plate and the resin is 1-1, it is advantageous in that even under conditions where the steel plate is exposed to commercial conditions, the misalignment with the steel plate and the outflow of the resin are reduced, and the defects in the laminated material are compensated for.

In order to strengthen such adhesive strength, not only is the adhesive strength (primary adhesion) during the production of composite laminated steel sheets important, but also the prevention of adhesive strength deterioration over time in adverse environments (secondary adhesion) is an important issue.

When a composite 61-layer steel plate is exposed to a corrosive environment such as salt water, corrosion is likely to occur particularly on the end face. When corrosion occurs on the end face, not only the corrosion itself but also the adhesive strength with the resin layer decreases due to the corrosion, which directly leads to a decrease in the straightness of the composite laminated steel plate as a whole, that is, a deterioration in the Tability.

The present inventor has proposed that, in order to achieve such secondary adhesion, the surface of the steel plate that will be in contact with the resin is coated with a chromate film. i;-
Apply chromate treatment containing Cr'+, and this coating 1f
By adding a water-soluble phosphoric acid compound and a water-soluble silane coupling agent to the +-type chromate treatment solution, the phosphoric acid group and silanol group react with the metal substrate and resin,
The present invention was based on the discovery that it strengthens the adhesion between metal and resin, works effectively to maintain corrosion resistance, improves secondary adhesion P[, and as a result, improves fluorinability.

That is, the present invention provides a composite laminated steel plate in which a polyolefin resin is sandwiched between steel plates as a thermally stable resin, wherein each of the steel plates is coated with a water-soluble phosphoric acid compound (A) only on the sandwiching surface of the thermoplastic resin. ) and silane coupling agent (
1)), and the ratio of the above additive to chromic acid is 0.2w'1%≦A+B≦5wL%, and 0.2
A method for producing a composite laminated steel sheet with excellent formability and corrosion resistance, characterized in that the process is performed using a chromate treatment solution with ≦A/B≦1.0 so that the amount of chromium deposited is 10 to 150 B/rn2. .

The configuration of the present invention will be explained in detail below.

Chromate treatment includes electrolytic chromate treatment, reactive chromate treatment, and coating type chromate treatment.

In the case of reactive chromate treatment, single-sided treatment is possible by spray treatment, but when cold-rolled steel sheets are used, it is difficult to ensure an appropriate amount of chromium deposited.

With electrolytic chromic acid treatment, it is easy to ensure an appropriate amount of chromium deposited, but because the material is immersed in the electrolytic chromic acid treatment solution, current equipment makes it difficult to avoid trace amounts of chromium depositing on untreated surfaces. First, complete single-sided processing is difficult. However, automobile parts are subjected to chemical conversion treatment in the paint shop, and this chromium oxide layer has an adverse effect on the chemical conversion treatment properties. For these reasons, composite damping steel plates used in automobile parts,
Alternatively, if a lightweight steel plate is to be chemically treated, it must be chromate treated on one side.

In the coating type chromate treatment of the present invention, the appropriate chromium 13
It is effective as a steel sheet pre-treatment for such composite laminated steel sheets because it is easy to ensure that the temperature is high, and single-sided treatment can be easily performed by roll coating. In addition, compared to electrolytic chromate treatment, paint-type chromate treatment has a small amount of Crt+", so when exposed to a corrosive environment, the protective effect of passivation of the defective part prevents deterioration of the bonded part. It is effective.

In the present invention, coating type chromate treatment is performed using a chromate treatment solution containing a water-soluble phosphoric acid compound.

The water-soluble phosphoric acid compound is particularly preferably a phosphoric acid-based organic compound, such as phosphoric acid, ammonium phosphate, alkali metal phosphate, phosphoric acid ester such as ethyl phosphate, 2-acryloyloxyethyl acid phosphate, etc. Representative examples include unsaturated phosphoric acid compounds and the like.

The phosphoric acid group in the water-soluble phosphoric acid compound reacts with the metal base of the steel sheet and at the same time strengthens the chromate film, improving the corrosion resistance of the composite laminated steel sheet.

Furthermore, in the present invention, a water-soluble silane coupling agent is added to the chromate treatment solution.

Typical water-soluble silane coupling agents include γ-glycidoxypropyltrimethoxysilane, γ-acinobrobyltriethoxysilane, and γ-(aminoethyl)aminopropyltriethoxysilane.

By adding a water-soluble silane coupling agent to the chromate treatment solution, the silanol group (-5i-Off) generated by hydrolysis of the silane coupling agent reacts with the metal base of the steel sheet, while the silane coupling agent contains The organic functional group (-5i-R) of reacts with fat. As a result, the bond at the interface between the steel plate and the resin is strengthened, and Gra+ and Cr6
Secondary adhesion than paint-type chromate treatment containing only +,
Improves end-face packing resistance.

Addition of a water-soluble phosphoric acid compound (A) and a water-soluble silane coupling agent (B) to the chromate treatment solution
l is O,'2wt%≦A1B≦5w with respect to chromic acid
t,% is preferable. If it is less than 0.2 wL%, there is no effect of improving corrosion resistance, that is, the secondary adhesion between the steel plate and the resin. If it exceeds 5 wL%, the chromate treatment solution is likely to deteriorate, and the solution may be destroyed. It is also preferable that 0, 2≦A/B≦1.0. Outside this range, no corrosion resistance improvement effect will be observed.

The amount of chromate deposited in the chromate treatment using the above chromate treatment solution is calculated as chromium on a steel plate. 71s1
O ~ 150wg/rn" is appropriate. If the chromate adhesion rit is less than 110l1/m" in terms of chromium per surface, the adhesion between the steel plate and the resin due to chromate treatment,
No improvement effect on moldability or corrosion resistance was observed, and 150II1
If it exceeds g/m', peeling within the chromate layer tends to occur, resulting in decreased adhesion and moldability.

The coating type chromate treatment used in the present invention is a general coating 11
R-type chromate treatment is a chromate treatment in which a reducing agent is added to an aqueous chromic acid solution, and is coated with a chromate treatment solution containing Cr3'', a water-soluble phosphoric acid compound, and a water-soluble silane coupling agent. It dries.

The steel plates used in the method for manufacturing laminated steel plates of the present invention include:
Of course, a cold-rolled steel plate subjected to a direct coating type chromate treatment is used, but a galvanized steel plate or the like subjected to the chromate treatment may also be used.

The outermost layer, that is, the surface in direct contact with the resin layer, has a coated chromate coating +1fi.

On the other hand, as thermoplastic resins, polyolefins and polyamides are effective from the viewpoint of moldability and heat resistance, but among polyamides, especially nylon, the adhesive strength of which is not improved by chromate treatment is low, and the adhesive strength is low. For the resin layer of the present invention, it is preferable to use an unmodified polyolefin, a modified polyolefin, a composition of a modified polyolefin and an unmodified polyolefin, or a composition to which other resins, inorganic fillers, etc. are added. Examples of unmodified polyolefins include homopolymers of ethylene, propylene, and 1-butyne, copolymers of different olefins, and mixtures thereof. A modified polyolefin is one that has been modified to give adhesive properties by modifying the unmodified polyolefin described above, or this modification can be done by using an unsaturated carboxylic acid such as acrylic acid, methacrylic acid, or maleic acid, or an anhydride thereof. It is possible to use compounds, esters, etc. Further, as the resin layer, a laminate of modified polyolefin layer-unmodified polyolefin layer-modified poly first nofin layer type may be used. Particularly preferred is polypropylonone.

In order to form the above-mentioned resin layer on a coated chromate-treated steel sheet, it is preferable to use a press molding machine or the like to press it with heating F, or to supply the resin from a melt extruder and press it with a roll.

<Example> Hereinafter, the present invention will be specifically explained based on Examples.

(Example 1 and Comparative Example) One side of a 0.6 mm thick cold rolled steel plate was treated with the coating type chromate treatment solution shown in 1 or more so that the amount of chromium deposited was 0 to 2501187 m2, and after the treatment, A composite vibration-damping steel sheet was created by sandwiching polypropylene resin.

Coating type chromate treatment liquid CrO340gir1 2-acryloyloxyaracid phosphate O~2g/Itγ-gelici p'-3-2propyl. ~2g/11 trimethoxone Cr3+/Gr'3+ = 0, 3 3
Cut out test specimens for measuring adhesive strength from this until shaken steel plate to steel plate, and measure T-peel strength and critical drawing ratio (
LDR) was measured. The results are shown in FIG.

(Example 2 and Comparative Example) One side of a cold-rolled steel sheet having a thickness of 0°2 nm was subjected to coating-type chromate treatment in the same manner as in Example 1, with a chromium deposition amount of 0 to 250 mg/m2. A light star steel plate was produced by sandwiching a polypropylene resin at a pressure of 0.6N+O+ between the steel plates.A strip-shaped specimen was cut from this lightweight steel plate, and its peel strength was measured in the same manner as in Example 1. In addition, in the case of lightweight steel products, shallow drawing or stretch forming is often used rather than deep drawing, so an Erichsen test was conducted and the Erichsen value was also measured. The results are summarized with the case of I11 shaken steel sheet in the second section.
Shown in the figure.

The T-peel strength was measured by measuring the initial T-peel strength (primary adhesion) and the secondary T-peel strength (secondary adhesion) after 1500 hours of the salt spray test, and is shown in FIG. The evaluation method is as described above.

O: Hatsumei T-type peel strength 14 g/c or more, Toerichsen value 10 mm or more, critical drawing ratio 1.95 or more Secondary T-peel strength 10 g/c or more Δ: Initial T-peel strength 14 Kg/c Eriksen value 10
! 1llB or more Limit aperture value 1.95 or more Secondary T-type peel strength 10 to g/c or less x: Initial T-type peel strength 14 to g/c to Erichsen value 1
01! lff1 or less Limit aperture value 1.95 or less As shown in the second river, the addition ratio of water-soluble phosphoric acid compound (A) and water-soluble silane coupling agent (11) is A/B or 0.
．． If it is outside of 2 to 1.0, the primary adhesion is good, but
Severely low secondary adhesion.

Moreover, if the amount of chromium deposited is too large, good results cannot be obtained in both primary adhesion and secondary stoneability.

In the present invention, the amount of chromium deposited and the amount of water-soluble phosphoric acid compound and water-soluble silane coupling agent added are set within appropriate ranges.
The primary adhesion of 0 chromium coating without chromate treatment is T-22 peel strength of 8 kg/c, while the T-type peel strength of primary adhesion is 14 kg/cI! "f" is 2, and 2
The adhesion is also T-type peel strength of 10 g/cd or more,
It can be seen that good adhesion is exhibited.

In addition, a composite laminated steel plate with a 0.6 mm thickness of nylon resin was sandwiched between the sheets, and the same characteristics tests were conducted using the same composite laminated steel plates as above. was not recognized at all.

<Effects of the Invention> As is clear from the above examples, the composite laminated steel sheet obtained by the manufacturing method of the present invention contains a water-soluble + 1F phosphoric acid compound in the sandwich between the steel sheet and the polyolefin resin as a thermoplastic resin. (A) and a water-soluble silane coupling agent (B), and the ratio of additive to chromic acid is 0.
2wL%≦A+B≦5w%, O12≦A/B≦1.0
With a chromate treatment solution, the amount of chromium deposited is 10 to 15.
The initial peel strength between the steel plate and the resin is strengthened by application-type chromate treatment to achieve 0 mg/ia', and the secondary peel strength in a salt spray environment is further strengthened, thereby improving the primary adhesion of composite laminated steel plates. It was possible to improve not only the initial formability but also the effect of preventing deterioration of the formability over time.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a composite laminated steel plate of the present invention. Figure 2 shows the deposition in terms of metal chromium in the coating type chromate treatment of Examples 1 and 2 of the present invention, and the addition ratio A of the water-soluble phosphoric acid compound (A) and the water-soluble silane coupling agent (8). It is a graph showing the relationship between /B and the T-peel strength of a steel plate and a resin. Explanation of symbols! ...Steel plate, 2.. Chromate treatment layer, 3.-thermoplastic/polymer resin layer Patent applicant Kawa IL2 Representative for Steel & Steel Co., Ltd. Patent attorney Nozomi Watanabe Zaima Patent attorney Yo Ishii -FIG, 1

Claims (1)

[Scope of Claims] A composite laminated steel plate in which a polyolefin resin as a thermoplastic resin is sandwiched between steel plates, wherein each of the steel plates contains a water-soluble phosphoric acid compound (A) only on the sandwiching surface of the thermoplastic resin. and silane coupling agent (
B), and the ratio of the above additive to chromic acid is 0.2wt%≦A+B≦5wt%, and 0.2≦A
A method for producing a composite laminated steel sheet with excellent formability and corrosion resistance, characterized by treating the steel plate with a chromate treatment solution in which /B≦1.0 so that the amount of chromium deposited is 10 to 150 mg/m^2.