JPH0235969A - Manufacture of embossed decorative material - Google Patents

Abstract

PURPOSE:To efficiently manufacture a decorative plate wherein a durable paint film is embossed by applying a thermosetting powder paint to a material plate, melting this paint by heating, embossing the paint before completion of the solidification and solidifying the same. CONSTITUTION:A thermosetting powder paint 2 is first applied to a material plate 1 and this paint 2 is then melted by a heater 3. The paint film thus formed is embossed by an embossing calender 4 while the content of the gel of the molten thermosetting powder paint formed by hardening reaction is within the range of 15-75wt.%. The paint film is thereafter reheated by a heater 5 for solidification. Such process brings about a satisfactory finish appearance and provides the powder paint excellent in anti-corrosion and weatherability for use in the embossing of steel plate, leading to the production of a decorative material free from cracking and worn-out polish standing long use.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a novel method for producing patterned decorative materials. More specifically, the present invention provides corrosion resistance, weather resistance,
Powder coatings with excellent abrasion resistance and good durability, such as no cracking or shrinkage of coatings even after long-term use, and are suitable for use in building materials, home appliances, furniture, etc. The present invention relates to a method for efficiently manufacturing a patterned decorative material which has been subjected to embossing treatment.

[Conventional technology] Traditionally, patterned decorative materials with excellent visual and tactile qualities have been used for construction materials such as wall materials and interior materials of buildings, housing materials for home appliances, and furniture to give a luxurious feel. Widely used.

Embossing is known as one of the methods for creating such patterned decorative materials, and embossed steel sheets have been put into practical use as patterned decorative materials subjected to this embossed processing, and are used for various purposes. ing.

This embossed steel plate is usually made by painting a vinyl chloride resin-based plastisol paint or organosol paint on a steel plate and baking it.
A coating film with a thickness of about 7 m, in the case of an organosol coating film,
It is created by forming a coating film with a thickness of approximately 0 to 100 μm and then performing embossing treatment.

However, in embossed steel sheets made by this method, the plastisol paints and organosol paints used contain large amounts of plasticizers such as dioctyl phthalate, so the plasticizers are gradually lost in the coating film over time. It has the disadvantage that it is prone to disappearing, causing cracks and shrinkage.

On the other hand, powder coatings have attracted attention in recent years because they have excellent processability, and the coating film has good weather resistance and abrasion resistance, and are typical resource-saving and non-polluting coatings. It is widely used for coating outdoor durable structures such as architectural steel frames, guardrails, fences, street lights, and gates, as well as industrial products such as steel furniture, electrical appliances, and enamel substitute coatings.

However, if this powder coating is applied to the surface of the object to be coated, baked-in is treated to form a coating film, and then the coating film is subjected to embossing treatment, cracks may occur at the edges of the uneven parts. Problems arise, such as when the corrosion resistance becomes extremely thin and its long-term corrosion resistance becomes poor, making it impossible to use it for a long period of time. Therefore, at present, embossed steel plates using powder coatings have not been put to practical use.

[Problems to be Solved by the Invention] Under these circumstances, the present invention uses a thermosetting powder coating that does not contain plasticizers, etc., and has excellent corrosion resistance, weather resistance, abrasion resistance, etc., and has a long-term durability. The object of this invention is to provide a method for producing a patterned decorative material that has been subjected to embossing treatment and has good durability such that the coating film does not crack or shrink even when used.

[Means for Solving the Problems] As a result of intensive research to achieve the above object, the present inventors found that there are two methods of embossing: one is embossing the raw material board and the coating film, and the other is embossing the coating film. It has been found that embossing of thermosetting powder coatings needs to be carried out under optimal conditions in each case.

First, when embossing the coating together with the raw material board,
It was discovered that there is a temperature difference between the temperature at which the coating is heated and melted and the temperature at which the curing reaction occurs, and that the coating film can remain in a fluid state for a certain period of time. The present invention was conceived based on the idea of embossing.

In addition, when embossing only the coating film, on the contrary,
The present invention was completed based on the discovery that it is necessary to strictly limit the curing conditions, and that if embossing is performed when the gel content of the cured film is within a certain range, a beautiful embossed decorative material can be produced.

That is, the present invention applies a thermosetting powder paint to a raw material board, heats and melts the paint, and before the curing reaction of the molten thermosetting powder paint is completed, the paint film is removed together with the raw material board. A method for producing a patterned decorative material by embossing and then heating to form a cured coating, and a method for producing a patterned decorative material by applying a thermosetting powder coating to a raw material board, heating and melting the coating, and applying the molten thermosetting powder to the substrate. To provide a method for producing a patterned decorative material by embossing only the coating film when the gel content is in the range of 15 to 75% by weight due to the curing reaction of the coating material, and then heating to form a cured coating film. be.

Hereinafter, the present invention will be specifically explained in further detail.

By using the present invention, embossing is performed while fluidity is maintained, and then baking is performed to form a hardened coating, which prevents defects such as cracking of the edges of uneven areas and excessive thinning. can.

According to the present invention, all thermosetting powder coatings can be used as the powder coating from the viewpoint of the mechanism of the manufacturing process.

For example, Figure 3 shows the results of differential thermal analysis of a general thermosetting powder coating (Reference: Metal Finishing (MET)
ALFIN I SHI NG) 1979, 3
In Figure 3, an endothermic reaction occurs between AB to dissolve the resin, an exothermic reaction between the resin and the curing agent occurs between CD, and fluidity is maintained between BC. Embossing can be performed between this BC.

The temperature increase rate during this time is determined according to the reaction rate of the curing reaction.
By making appropriate adjustments, any type of thermosetting powder coating can be brought into a state where appropriate embossing can be carried out.

The material plate used in the method of the present invention is preferably a flat plate in that the resin is not unevenly distributed, but it is not necessarily limited to a flat plate, and curved plates can also be used.

Examples include steel plates such as thick and medium plates, thin plates, and galvanized iron plates, aluminum plates, wood plates, plywood, and plastic plates. Among these, steel plates are particularly suitable. When embossing together with raw material boards, non-malleable wood boards cannot be used.

In the method of the present invention, a powder coating mainly composed of a thermosetting resin is first applied to the surface of these raw material plates, but before applying the powder coating, the substrate of the object to be coated is usually prepared. will be held.

The purpose of this substrate preparation is to create a surface condition that will allow the paint film to completely adhere to the surface of the raw material board and maintain long-term durability, and there are no particular restrictions on the method of substrate preparation. Conventionally used methods can be used depending on the material of the raw material plate. For example, when using a steel plate as a flat plate-like substrate, surface preparation usually includes degreasing treatment, rust removal treatment, chemical conversion coating treatment, etc. Geography is given.

The surface of the raw material board prepared in this manner may be coated with a primer coating, if desired, in order to further improve the adhesion of the powder coating film.

It is suitable for this primer coating to be compatible with both the substrate and the powder coating film, and it serves as a guide for adhesion of the powder coating to the substrate. Generally, the thickness of the coating film is about 10 μm. , Usually after applying a primer, a baking drying process is performed.

The powder coating used in the method of the present invention is not particularly limited as long as it has a thermosetting resin as its main component, but it is preferably one with excellent weather resistance, such as epoxy powder coating, polyester powder Body paints, acrylic powder paints, etc. are preferably used, and as crosslinking agents, resins such as melamine, blocked isocyanates, polybasic acids/amides, etc. can be used.

There are no particular restrictions on the application method of these powder coatings, and conventional methods commonly used for powder coating, such as thermal spraying,
The spraying method, fluidized dipping method, electrostatic spraying method, electrostatic dynamic dipping method, etc. can be used, and among these, the electrostatic spraying method is preferable.

The electrostatic spraying method involves spraying negatively charged powder paint onto a grounded object through the nozzle of a spray gun to which a high voltage (-70,000V or more) is applied, and then it is electrically attracted and adhered to the object. This is the way to do it.

In the method of the present invention, a plate-shaped substrate which has been prepared and coated with a primer as desired is coated with
After preheating to a temperature of about 80° C., thermosetting resin powder is applied to the surface by the method described above. At this time, the thickness of the coating film is usually selected within the range of 30 to 200 μm.

Next, this is heated to a temperature higher than the melting temperature of the powder coating,
After the powder coating is melted and while it remains fluid, it is subjected to an embossing treatment using an embossing roll or press.

It is advantageous to use an embossing roll or the like that is water-cooled or whose surface is treated with fluororesin so that fluid powder coatings are less likely to adhere to it.

Examples of the fluororesin include tetrafluoroethylene resin,
It is preferable to use a material with extremely high non-adhesive properties such as ethylene trifluoride resin.

In the present invention, when embossing is performed together with the raw material plate, the molding is performed before curing is completed, and the curing reaction is completed after molding, so that no distortion remains after embossing, and no cracks or the like occur.

In addition, when embossing only the coating film, which is another embodiment of the present invention, during the curing reaction of the applied powder coating,
Gel content is 10-75% by weight, preferably 25-60%
It is necessary to perform embossing when the weight percentage is within the range.

If the gel content is lower than 10% by weight, the shape will collapse due to heat after embossing, making it impossible to obtain an accurate embossed pattern. Furthermore, when the gel content exceeds 75% by weight, rubber elasticity occurs in the powder coating film, so that an uneven pattern is not formed and the finished appearance of the coating film becomes poor.

The gel content in the present invention is obtained by collecting a coating film during curing, extracting it with tetrahydrofuran under reflux for 5 hours, drying the residue, and calculating the ratio by weight to the amount collected.

In the present invention, the gel content in the coating film is determined in advance through a preliminary test in accordance with the heating pattern of the manufacturing conditions, the appropriate gel content is selected, and the embossing is performed at an appropriate timing. It is desirable to implement it.

In the manufacturing process of the present invention, after embossing, baking is performed by heating in a furnace to complete the hardening reaction.

In this way, an embossed pattern can be formed without causing molding distortion.

In the manufacturing method of the present invention, all steps can be performed continuously while the materials are continuously transferred on a conveyor.

[Example] Next, examples of preferred embodiments of the present invention will be described with reference to the accompanying drawings.

Example 1 FIG. 1 is a process diagram for embossing the entire coating material.

Figure 1 shows an example of a coating line suitable for carrying out the method of the present invention. ing.

Process I A steel plate that has been previously subjected to degreasing treatment, rust removal treatment, and chemical coating treatment is used as the raw material plate 1, and a polyester resin powder coating is sprayed onto the surface of the steel plate with a powder coating machine 2 to achieve a film thickness. Electrostatic spraying was performed so that the thickness was approximately 50 μm.

Process■ Next, this material is passed through the heating furnace 3 to a temperature of approximately 130°C.
: The powder coating was heated for 1 minute to melt and fluidize it.

Step (2) Next, the coating material was passed between embossing rolls 4 (A) and 4 (B), and as shown by coating material 6, the entire coating material together with the raw material board was subjected to embossing treatment.

Step (2) The embossed coating material was baked at a temperature of 250° C. by passing through a furnace 5 for 3 minutes to harden it, thereby producing an embossed steel plate 8.

The embossed steel plate thus obtained had a beautiful appearance, had no cracks, and did not exhibit any cracks or shrinkage even after being exposed outdoors for 100 days.

Examples 2 to 6 FIG. 2 shows a process diagram when only the coating film is embossed according to the present invention.

The indicated thermosetting powder coating was applied by electrostatic powder coating. This was heated at the indicated temperature for the indicated time and then embossed using embossing rolls 4'A and 4''B.

The embossing roll used in embossing had an uneven pattern on its upper surface facing the coating film, and a simple flat roll was used as the lower roll 4'B.

Next, the coated material with the embossed coating was heated in a furnace 5 at the indicated temperature and for the indicated time to complete the curing reaction of the coating.

During the embossing process, the coating film at the edge of the raw material board at the moment of embossing was sampled and the gel content was measured.

The finished appearance of the coating film of the final product was observed.

Comparative Examples 1 to 3 In the same manner as in Example 2, the indicated powder coatings were embossed under the indicated conditions, and the gel content was measured and the finished appearance was observed.

The results of Examples 2 to 6 and Comparative Examples 1 to 3 are shown in the table.

(The following is a blank space) [Effects of the invention] As explained in detail above, the present invention enables the use of a powder coating with a good finished appearance, heavy corrosion resistance, and excellent weather resistance as an embossed steel plate, thereby replacing the conventional PVC. It is possible to provide a new embossed steel plate without defects such as cracks, shrinkage, etc. that embossed steel plates such as steel plates have.

The patterned decorative material obtained by the method of the present invention is suitably used as, for example, building materials such as wall materials and interior materials of buildings, housing materials for home appliances, furniture materials, and the like.

[Brief explanation of the drawing]

FIG. 3 is a diagram showing a general chart for differential thermal analysis of thermosetting powder coatings, and FIG. 1 is a schematic diagram of a coating line for carrying out general embossing with the stock plate of the present invention. FIG. 2 is a schematic diagram of a coating line for embossing only a coating film according to the present invention. The symbols in the diagram are l...Raw material board wave coating, 2...Powder coating machine, 3...Heating furnace, 4A, 4B, 4'A, 4'B
... Embossing roll, 5... Baking furnace, 6... Embossed coating material.

Claims (1)

[Claims] 1. A thermosetting powder coating is applied to a raw material board, the paint is heated and melted, and the coating is applied together with the raw material board before the curing reaction of the molten thermosetting powder coating is completed. A method for producing a patterned decorative material by embossing a film and then heating it to form a cured coating film. 2 Apply a thermosetting powder coating to a raw material board, heat and melt the coating, and when the gel content is in the range of 15 to 75% by weight due to the curing reaction of the molten thermosetting powder coating, only the coating film is formed. A method for producing a patterned decorative material by embossing and then heating to form a cured coating film.