JPS6372538A - Precoated steel plate - Google Patents

Abstract

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

Description

Detailed Description of the Invention (Field of Industrial Application) This invention combines specific reinforcing fibers into a film-forming component that hardens by baking to improve scratch resistance, hardness, flexibility, adhesion, and weather resistance. The present invention relates to pre-coated steel sheets with improved coating properties.

Currently, pre-coated steel sheets are used in a wide range of fields, including building materials such as roofing materials, exterior wall materials, interior materials, storm doors, and shutters, as well as home appliances, vehicles, and steel furniture.

(Prior art) Coating film materials for such pre-coated steel sheets include alkyd resins, amino alkyd resins, polyester resins, epoxy resins, epoxy ester resins, acrylic resins, silicone-modified polyester resins, and silicone resins. A variety of materials have been used, including modified acrylic, vinyl chloride-1 fat, F/-1 grease-resistant, and fluororesin, but all of these materials have poor hardness, scratch resistance, and moxibustion resistance. Problems remained in terms of durability, corrosion resistance, and workability.

Therefore, various attempts have been made to solve the above problems.
4 and 57-177379), a method of adding resin powder with high hardness (Japanese Patent Application Laid-open No. 58-83067 and 57-177379),
No. 8-83068 and No. 59-123655) have been proposed.

(Problems to be Solved by the Invention) According to each of the above methods, it was possible to improve one or two characteristics of the frames required depending on the purpose, but the It has not been possible to obtain a prepainted steel sheet that combines hardness, scratch resistance, weather resistance, corrosion resistance, and workability, and its development has been desired.

The present invention advantageously meets the above requirements and proposes a prepainted steel sheet that has all the properties required of a prepainted I sheet, such as high hardness, good scratch resistance, weather resistance, corrosion resistance, and workability. The purpose is to

(Means for Solving the Problems) As a result of extensive research in order to solve the problems of the prior art as described above, the inventors found that baking is a hardening type film forming component. After much trial and error, they discovered that the intended purpose could be advantageously achieved by using a mixture of the main elements and specific reinforcing fibers, leading to the completion of this invention.

In other words, the present invention includes 50 to 95% by weight of a bake-curable film-forming main element as a film-forming component in terms of solid content.
This is a pre-coated steel sheet made by coating and baking a vehicle containing 5 to 50% by weight of potassium titanate fibers on the surface of a base steel sheet.

This invention will be explained in detail below.

The baking used in this invention is the main element for forming a hardening type film, needless to say, oil-based or water-based varnish is used.
Any material commonly used in the paint field may be used, including varnishes made from natural oils or processed oils, alkyd resins, polyester resins, epoxy resins, etc.
Paints such as epoxy ester resins, aminoalkyd resins, acrylic resins, vinyl chloride resins, phenolic resins, silicone-modified acrylic resins, silicone-modified polyester resins and fluororesins are advantageously suitable.

In this invention, potassium titanate fiber is added to the main film-forming elements as described above, and the blending ratio of the two is 50 to 95% by weight in terms of solid content.
(hereinafter simply expressed in %) is preferably 65 to 85%, while the latter should be limited to a range of 5 to 50%, preferably 15 to 35%. This is because if the blending amount of potassium titanate and fiber is less than 5%, the effect of improving hardness, scratch resistance, weather resistance, etc. will be poor, while if it exceeds 50%, processability will deteriorate.

Here, the potassium titanate fiber has a fiber length of 1.
It is desirable to use a material in the range of ~100 μm. This is because if the fiber length is less than 1 μm, coating film 4 tends to thicken, and even when it becomes a coating component, it precipitates under the coating film, making it difficult to improve hardness and scratch resistance sufficiently. On the other hand, if the diameter exceeds 100 μm, strong stirring will be required at all times in order to uniformly distribute the potassium titanate fibers in the paint, and roll coaters, curtain flow coaters, and bar coaters may be used. When applying the product with a paint, etc., a scuffing phenomenon is observed, making it difficult to obtain a uniform coating on the surface, and furthermore, the potassium titanate fibers tend to fall off from the coating, resulting in cracking and peeling during processing. This is because it becomes easier. Note that as the fiber length range becomes smaller, the final coating film becomes more uniform.
The narrower the fiber length range, the better.

Further, if the diameter of the potassium titanate fibers is too small or too large, the same disadvantages as mentioned above will occur, so it is preferable that the diameter of the fibers 4ii is about 0.1 to 50 μm.

Now, potassium titanate fibers are blended as the main element for film formation in the above preferred range, and diluted with a solvent as necessary.
Applying a vehicle consisting of ffi liquid to the surface of the base steel plate,
A coating film is formed by baking, and any conventionally known method such as a roll coater method, curtain flow coater method, or bar coke method can be used for the application.
It can be used and baked at 180-300℃, 0.5℃.
It is preferable to carry out the heating for about 5 to 3 minutes.

Moreover, as the base steel plate, not only general cold-rolled steel plates but also those subjected to chemical conversion treatment, plating treatment, or even primer treatment can be suitably used.

The thickness of the coating after baking is preferably about 5 to 40 μm.

(Function) According to the present invention, by using a mixture of potassium titanate fibers as a main element for forming a bake-hardened film as a film-forming component, it is possible to improve not only hardness but also scratch resistance, weather resistance, corrosion resistance, and processability. The reason why physical characteristics such as sex improve has not yet been clearly elucidated, but it is thought to be as follows.

Potassium titanate fibers dispersed in the coating function as fillers similar to pigments, providing particle reinforcement and stress relaxation functions.

(Example) Examples of the present invention will be described below. In addition, parts and percentages in the examples are weights in terms of solid content unless otherwise specified.

Example 1 Baking is the main element for forming a hardening film using epoxy paint A.
To 190 parts, 10 parts of potassium titanate fiber B1 (Kubokuchikunate potassium fiber B1 fiber length 10 to 50 μm, single yarn diameter 0.5 to 2.0 μm, manufactured by Kubota Tekko Co., Ltd.) was blended, and 100 to 100 parts was mixed with a stirrer. The mixture was stirred and mixed at 600 rpm to form a vehicle.

The above compounded paint was applied to a zinc phosphate treated hot-dip galvanized steel sheet (Z25) with a thickness of 0.35 mm using a bar caulk so that the dry film thickness was 10 μm, and then the maximum plate temperature: 200°C, Processing time: Baking was performed for 115 seconds.

The results of investigating the coating film properties of the thus obtained pre-coated steel sheet are shown in Table 1.As is clear from the results shown in Table 1, potassium titanate fibers can be added to the Epoquine paint according to the present invention. As a result, it was possible to improve hardness, scratch resistance, weather resistance, and corrosion resistance without causing a decrease in workability.

Example 2 Coating film performance of a pre-coated steel plate obtained in the same manner as in Example 1 except that the mixing ratio of epoxy paint 1 to 1 used in Example 1 and potassium titanate fiber B was changed to 80:20 The results of the investigation are shown in Table 1.

As is clear from the results, even if the amount of potassium titanate fiber added was increased, results similar to or even better than those of Example 1 were obtained.

Example 3 The blending ratio of Epoquin-based Fumishina Δ1 and potassium titanate fiber 1flj B 1 used on both sides was 70.
A pre-painted steel plate was obtained in the same manner as in Example 1 except that the steel sheet was changed to:30. Table 1 shows the investigation results regarding the coating film performance.

Further improvement in scratch resistance was achieved by increasing the amount of potassium titanate fibers added.

Example of 5 cans t1 Baking is a polyester paint A280 as the main element for forming a hardening film! After 8.20 parts of potassium titanate fiber was added to the mixture, the mixture was dispersed and mixed uniformly using a stirrer to prepare a vehicle.

In addition, as the base steel plate, 0, 35 treated with zinc phosphate is used.
An epoxy primer was applied as a primer to the hot-dip galvanized steel If (225) with a dry film thickness of 5 μm.
A primer-treated steel plate was used, which was coated with the primer and baked under the conditions of a maximum plate temperature of 200° C. and a treatment time of 230 seconds.

The above vehicle was applied as a top coat to the surface of the primer-treated steel plate, and a dry film thickness of 15 μm was obtained by roll caulking.
The highest board temperature reached was 240℃,
Processing time: 60 seconds Baking: Rida.

Table 1 shows the results of examining the physical properties of the coating film of the precoated steel sheet thus obtained.

As is clear from the results in Table 1, the addition of potassium titanate fiber B improves hardness, scratch resistance, weather resistance, and corrosion resistance without reducing workability even when the type of paint is different. A pre-coated steel sheet is obtained.

Example 5 Polyester paint A2 was applied to the surface of the primer-treated steel plate used in Example 4 to a dry film thickness of 13 μm using a bar coater, and then potassium titanate fiber B1 was applied thereon to a dry film thickness of 2 μm. The pre-coated steel sheet was baked under conditions such as maximum plate temperature: 240°C and processing time: 60 seconds.

Table 1 shows the coating film performance of the pre-coated steel sheet obtained in this manner.

As is clear from the results in Table 1, even if the method of adding potassium titanate fibers is changed, the hardness, scratch resistance, and
A pre-coated steel plate soaked in oxidation was obtained.

Example 6 Example 4 except that 20 parts of potassium titanate fiber B was blended with 380 parts of silicone/polyester paint A, and the vehicle obtained by uniformly dispersing and mixing with a stirrer was used as the top coat. A prepainted steel plate was prepared in the same manner as above.

The coating performance is shown in Table 1.

Even if the type of paint was changed to a silicone/polyester type, pre-coated steel sheets with deteriorated physical properties of the paint film were obtained.

Example 7 A precoated steel plate was obtained in the same manner as in Example 4 except that 5 parts of potassium titanate fiber B was added to polyester paint A295fflS.

The coating performance is shown in Table 1.

As is clear from the results in Table 1, even when the potassium titanate fiber B1 was added in a small amount of about 5%, a precoated steel sheet with poor coating film properties was obtained as in the previous examples.

Example 8 A precoated steel plate was obtained in the same manner as in Example 4 except that the amount of potassium titanate fiber B (1) was changed to 40 parts.

Table 1 shows the results of coating film evaluation.

From the results in Table 1, it can be seen that even if the amount of potassium titanate fibers added is increased, a precoated steel sheet with clear coating film properties as in Example 4 can be obtained.

Example 9 Fluorine thread paint A4 (OF-228, Dainippon Ink Co., Ltd.)
! A pre-coated steel plate was obtained in the same manner as in Example 4, except that the coating material was used as a top coat.

Table 1 shows the results of coating film evaluation.

From the results in Table 1, it can be seen that even when potassium titanate fibers are added to the fluorine thread coating, scratch resistance, hardness, etc. are improved.

Comparative Example 1 Polyester coating (・4828 [1ε: also) Nimon [shi,
Potassium titanate material day i! Example 4 except that 20 parts of 32 (potassium kuhokuchinic acid 2.J, fiber △, fiber length 10θ~5t) 0 μm, single fiber diameter 10~30 μm, manufactured by Kubota Iron Company) were blended at a ratio of 20 parts. A prepainted steel plate was obtained in the same manner.

Table 1 shows the results of coating film evaluation.

As is clear from the results in Table 1, when a large amount of potassium titanate fibers with a length of 100 μm or more is mixed into the coating film, the potassium titanate fibers are unevenly distributed on the surface layer, resulting in a smooth coating film. was not obtained. Furthermore, although the hardness was improved, the workability was poor.

Comparative Example 2 Polyester paint A 245%, potassium ticunate, became sticky and the workability of the paint film deteriorated.

Comparative Example 3 A precoated steel plate was obtained in the same manner as in Example 4, except that 3 parts of potassium titanate fiber B was added to polyester paint A297N.

The results of coating film evaluation are shown in Table 1.

Even though the amount of potassium titanate sacrificial fiber added was small, a satisfactory coating film improvement effect was not obtained.

Comparative Example 4 A pre-coated steel plate was obtained in the same manner as in Example 1 except for the Epoquin paint A1.

Table 1 shows the results of coating film evaluation.

Those to which potassium titanate fibers were not added were inferior in hardness and scratch resistance.

Comparative Example 5 A pre-coated steel plate was obtained in the same manner as in Example 4 using only polyester paint A2.

Table 1 shows the results of coating film evaluation.

When potassium titanate fibers were not added, only results similar to those of Comparative Example 3 were obtained.

Comparative Example 6 A pre-coated steel plate was obtained in the same manner as in Example 4 using only silicone polyester paint A3.

Table 1 shows the results of coating film evaluation.

Even when silicone/polyester paints were used, those without potassium titanate fibers had poor processability.

Comparative Example 7 A pre-coated steel plate was obtained in the same manner as in Example 4 using fluorine thread paint A.

Table 1 shows the results of coating film evaluation.

Even when fluorine thread paints were used, those without added potassium titanate fibers were inferior in hardness and workability.

(Effects of the Invention) Thus, according to the present invention, it is possible to obtain a pre-coated steel sheet that has not only high hardness but also excellent scratch resistance, weather resistance, corrosion resistance, and workability.

Claims (1)

[Claims] 1. A vehicle containing, as film-forming components, 50 to 95% by weight of a bake-curable film-forming main element in terms of its solid content, and 5 to 50% by weight of potassium titanate fibers. , a pre-coated steel plate made by coating and baking the surface of a base steel plate. 2. The precoated steel sheet according to claim 1, wherein the length of the potassium titanate fibers is in the range of 1 to 100 μm.