JPH01219080A - Production of coated carbon fiber-reinforced concrete plate - 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 producing concrete plates useful as building materials reinforced by incorporating carbon fibers, and particularly effective for the purpose of aesthetic finishing. The present invention relates to a method of manufacturing a carbon fiber reinforced concrete plate.

[Conventional technology]

The inherent disadvantage of the brittle nature of cementitious matrices can be significantly improved by dispersing them with appropriate amounts of suitable fibrous materials, such as carbon fibres. In recent years, it has become possible to mass-produce inexpensive pitch-based carbon fibers, and the practical use of carbon fiber reinforced concrete (hereinafter referred to as rCF RCl) has progressed further.
．． 0) X 1'06kg/cjt" CFRC board mixed with 0.5 to 20.0% carbon fiber by volume has been developed (
JP-A No. 58-204856), it is highly anticipated as a new structural material with strength, deformation, and elasticity properties that were previously unattainable with cement concrete.

On the other hand, cement products containing the above-mentioned materials are generally coated with various paints in order to improve performance such as durability, weather resistance, stain resistance, water resistance, and cosmetic properties. Conventionally, when painting for this purpose, painting was done after the cement product had completely hardened to prevent the paint film from deteriorating or reducing adhesion due to the alkaline content generated during curing. . However, with this method, the curing process and painting process of the cement product must be completely independent, so disadvantages in the process cannot be avoided, and various efforts have been made to improve this as much as possible. . For example, a method of applying a hydraulic coating material to uncured concrete and curing it with steam to produce a precast concrete board (Japanese Patent Publication No. 53-27735), a method of first curing a wet cement raw board and then applying a thermoplastic resin paint. A method has been proposed in which the material is then subjected to final curing in an autoclave and further coated with a resin paint (Japanese Patent Laid-Open No. 57-51187).

Incidentally, in the production of CFRC boards, autoclave curing is essential for the reasons of maintaining dimensional tolerances in units of 1 and improving strength. This is very different from glass fiber reinforced concrete and steel fiber reinforced concrete, which are also fiber reinforced concrete but are steam cured due to heat and rusting. The autoclave conditions when creating a CFRC board are extremely severe high temperature and high pressure conditions of 150 to 200°C, 5 to 15 atm, and 4 to 6 hours. For this reason, if the paint is applied before curing, the alkaline deterioration of the paint film will be accelerated due to long-term heating, significant efflorescence will occur, and significant blistering will occur due to high pressure steam. From this background, it is an unwritten rule that CFRC boards should be painted after being cured in an autoclave.

In addition, for the CFRC board that has been autoclaved, forced curing in an alkaline atmosphere slows down the rate of alkali neutralization, allowing the panel to remain in a strongly alkaline state for a long period of time. Furthermore, by mixing hydrophobic carbon fibers, the concrete material becomes more heterogeneous, which tends to cause air bubbles and cavities to occur, which also tends to cause minute cavities to occur in the finished surface.

Therefore, although CFRC boards have very excellent characteristics as a material, when considering decorative coating finishes, it is necessary to use particularly high-performance coating materials and base preparation compared to general precast concrete boards. etc. is required.

The current process of making CFRC boards and the general process of painting finished panels is shown as a flow sheet as shown in Figure 1.

In Figure 1, casting of Al CFRC raw material means placing CFR into a formwork created for any required panel shape.
This is the process of pouring the C raw material, and the preliminary curing of A2 is a process in which the panels are removed from the formwork and the panel shape is naturally maintained so that many panels can be stacked and placed in the autoclave pot in order to efficiently perform autoclave curing. This is a process carried out for the purpose of developing the strength to the extent that it can be achieved, and is usually
It is carried out at ℃ for about 5 to 6 hours.

A3 demolding is the process of removing the panel from the formwork, a
The autoclave curing in Step 4 is a process carried out to quickly and efficiently develop the necessary strength while maintaining the dimensional tolerance of the unit, and is preferably carried out at 180°C and 10 atm.
It will be carried out for about 6 hours.

The preparation of the surface of A5 is the process of filling the minute cavities of the CFRC board created by autoclave curing and removing substances that inhibit adhesion (such as scum) when applying paint.
The next step, A8, is a sealer, which is a treatment process performed for the purposes of strengthening adhesion, strengthening surface brittleness, preventing displacement foaming, stopping alkali, and preventing suction of paint that is to be applied again. Furthermore,
Filler (a) and surfacer (a8) are
This process is usually used to stop alkali, waterproof the panel, make it smooth, prevent foaming, add a sense of texture and design, and the final top coat (A9) is used to add waterproofness, weather resistance, design, aesthetics, etc. This is a processing step that is carried out for a specific purpose.

[Problem to be solved by the invention] As mentioned above, autoclave curing is essential for the production of qFRc boards, which has the disadvantage of requiring a careful painting process after autoclaving. Ta.

Therefore, as a result of various studies in view of the above circumstances, the inventors found that cement is contained in a limited range on the decorative layer applied surface of the CFRC board after demolding (a3), which has not yet completely hardened.゛ If paint (filler A7) is applied directly and then cured in an autoclave (A4), a normal coating film will be maintained even under high temperature and high pressure conditions of 150 to 200°C and 5 to 15 atm for 4 to 6 hours. Furthermore, this method eliminates the need for the steps of substrate preparation (a5) and sealer (a6), and has the advantage of being able to perform panel curing and filler curing at the same time. We discovered that the autoclave effect appears in the filler itself and contributes to performance improvement. The present invention has been made based on these findings.

[Means to solve the problem]

That is, the method for manufacturing a painted carbon fiber reinforced concrete board according to the present invention has a tensile elastic modulus of (0.3 to 1.0).
X 106kg/CD carbon fiber 0.5~20.0
% (volume ratio) of carbon fiber reinforced concrete is pre-cured, and the organic synthetic resin component 1 is added to the obtained pre-cured panel.
00 parts by weight (solid content), cement component 100-1500
After applying a paint whose main component is part by weight (solid content), the carbon fiber reinforced concrete panel and the paint are simultaneously cured in an autoclave at a temperature of 150 to 200°C and a saturated water vapor pressure of 5 to 15 atm. Features.

Generally, cement-based board materials are (0.08~0.23) xl
Since the tensile elastic modulus is about Q6kg/c-, the carbon fiber foil used as a reinforcing material is 0.3~1.0)81
If it has a tensile elastic modulus of 0.06 kg/cd, a practically sufficient reinforcing effect can be obtained. In particular, when a lightweight aggregate such as shirasu or pearlite is blended, the tensile elastic modulus of the base material decreases, so the strength can be further improved by mixing the carbon fibers.

When carbon fiber is mixed in at a mixing ratio of 0.5 to 20% (volume ratio), strength sufficient for practical use is imparted.

The paint to be applied to the CFRC pre-curing panel is one whose main components are 100 parts by weight (solid content) of an organic synthetic resin component and 100 to 1500 parts by weight (solid content) of a cement component.

A paint containing this cement has an organic synthetic resin solid content of 1
00 parts by weight to 100-1500 parts by weight of cement (
The reason for this is that when the organic synthetic resin content increases,
Although film-forming properties and workability are good, the paint film has no air permeability, and high-pressure water vapor causes significant blistering during autoclave curing, making it unusable for practical use.Also, it contains a large amount of cement. This is because the workability becomes poor and brittle, and efflorescence occurs as it approaches the cement material, resulting in poor adhesion to the topcoat and durability. From the viewpoint of workability, adhesion, autoclave effect, and durability, a more preferable range is 200 to 200 parts by weight of cement per 100 parts by weight of organic synthetic resin solid content.
It is 1000 parts by weight (solid content).

The cement used in this paint is usually Portland cement, but it is not limited thereto, and various cements and various combinations of strings are possible.

In addition, as for the synthetic resin used, all resins that are miscible with cement can be used, and water-based emulsion resins such as acrylic, vinyl acetate, and epoxy are usually used, but acrylic resins that are miscible with cement can be used. Of course, organic solvent-soluble resins such as vinyl acetate, epoxy, and the like can also be used.

Here, we limited the resin that can be mixed with cement to organic synthetic resins because inorganic resins such as sodium silicate may dissolve, elute, or volatilize during autoclave curing at high temperature and high pressure in a strong alkaline atmosphere. This is because

In addition to the above organic synthetic resin and cement, this paint contains
Extender pigments, color pigments, aggregates, fillers, dispersants, film-forming aids, thickeners, water, organic solvents, etc. that are normally used in paints,
It can be arbitrarily blended into paints for reasons such as workability, texture, coating performance, and cost.

Autoclave curing of CFRC panel is 150 to 20
The reason why it is 5 to 15 atm at 0℃ is that the lower limit of 150℃, 5
If the pressure is lower than atmospheric pressure, it will take time for the panel to develop its strength, and the dimensional tolerance of the panel will increase. The reason why the upper limit is 200℃ and 15 atm is because this is the practical limit for the vapor pressure of water, which is 180℃.
, the condition is 10 atm.

Most preferred.

The paint can be applied effectively by conventional spraying or troweling, but is not limited to these methods.
An appropriate method can be selected depending on the process requirements and the final desired texture.

[For production]

According to the present invention, since autoclave curing is performed after coating a CFRC pre-cured panel, it is possible to form a dense and strong coating layer due to the effects unique to this process.

Furthermore, because processes such as base preparation and sealer can be omitted, manufacturing efficiency is significantly improved.

〔Example〕

Examples of the present invention will be described below in comparison with comparative examples.

Table 1 shows the compounding composition of the CFRC used in this example, and Table 2 shows the coating composition of the example and comparative example.

Table-1 In addition, resins (A) to (1) in Table-2 refer to the following, respectively.

Resin (A) 2φ ethylhexyl acrylate-acrylonitrile copolymer emulsion (resin solid content 55%) Resin (B) 2φ ethylhexyl acrylate-styrene copolymer emulsion (resin solid content 55%) Resin (C) Vinyl acetate-n/butyl acrylate copolymer emulsion (resin solid content 55%) Resin (D) Methyl methacrylate-n/butyl acrylate copolymer
(Resin solid content 50%) Resin (E) Methyl methacrylate - 2-ethylhexyl acrylate -
Styrene copolymer emulsion (resin solids 50%) Resin (F) Ethylene-vinyl acetate copolymer emulsion (resin solids 45%) Resin (G) Epoxy emulsion (resin solids 55%) Resin () I) Methacrylic Methyl acid-n/butyl acrylate copolymer emulsion (resin solid content 50%) Resin (1) No. 3 sodium silicate (resin solid content 50%) Table -
The coating composition of 2 was sprayed onto a pre-cured CFRC panel that had been pre-cured at 40°C for 5 hours, and then placed in an autoclave together with the panel at a temperature of 150-190°C and a saturated water vapor pressure of 5-12 atm. Curing was carried out for 4 hours.

In addition, for comparison, the paint composition shown in Table 2 was similarly sprayed onto ordinary CFRC boards that had been autoclaved at 180°C and 10 atm. It was naturally dried in a constant temperature and humidity room for 7 days. Furthermore, some comparisons were made regarding conventional general coating specifications for CFRC boards. The amount of paint applied is approximately 1.5kg/rr? The coating thickness was approximately one fin.

The condition and adhesion of the resulting coating films were examined, and if possible, various top coats were applied, and alkali resistance tests and freeze-thaw tests were conducted.

Table 3 shows the state of the coating film after autoclaving and the results of the adhesion test using the Kenken adhesion tester.

Table 4 shows the results of various tests after the top coat was applied. However, the top coat paints in the Examples and Comparative Examples are merely examples, and the coating applied to the present invention is not limited thereto.

In addition, the test method and evaluation were performed as follows.

(1) Test method 1, Alkali resistance test Immersion in saturated calcium hydroxide solution, 30 days 2, Freeze-thaw test (20℃ tap water immersion, 16:00 - 20℃ freezing, 4 hours → 50℃ drying, 4 hours ) cycle, 80 cycles.

(2) Evaluation Evaluation of blisters and cracks is based on the Japan Paint Inspection Association's ``Coating Film Evaluation Standards''.

◎: No abnormality at all.

O: There is an abnormality only in a very small part.

Δ: Overall abnormality is observed, but the degree is relatively good.

×; Abnormality found throughout.

〔Effect of the invention〕

As is clear from the above examples, the coated carbon fiber reinforced concrete board of the present invention can also be produced by a simple process of coating a pre-cured CFRC panel with a paint composition and then curing the panel together with the panel in a high-temperature, high-pressure autoclave. Regardless, no abnormalities such as blisters or cracks were observed, and the paint film maintained a normal state.

Additionally, by curing the panel in an autoclave, a dense coating layer with excellent adhesion was formed, and the strength of the coating was significantly improved. As a result, the coating film performance has improved and adhesion with various top coat paints is also good, and it has been confirmed that it is not only comparable to the coating specifications of conventional painting processes, but also exhibits extremely excellent durability. It was done.

Furthermore, according to the present invention, since the painting process is applied directly to the CFRC panel before autoclave curing, special base preparation and sealer painting processes can be omitted. Since the required natural curing is no longer necessary, it is possible to significantly shorten process time, save labor costs, save paint, etc., and bring about various effects in terms of manufacturing production efficiency.

[Brief explanation of the drawing]

FIG. 1 is a flow sheet showing the current CFRC production process and the general painting process for finished panels.

Claims (1)

[Claims] (1) Tensile elastic modulus is (0.3 to 1.0) x 10^6k
Carbon fiber reinforced concrete containing 0.5 to 20.0% (volume ratio) of carbon fiber of g/cm^2 is pre-cured, and 100 parts by weight (solid content) of an organic synthetic resin component is added to the obtained pre-cured panel. After applying a paint whose main component is 100 to 1500 parts by weight (solid content) of a cement component, the carbon fiber reinforced concrete panel and the paint are placed in an autoclave at a temperature of 150 to 200°C and a saturated water vapor pressure of 5 to 15 atm. A method for producing a painted carbon fiber-reinforced concrete board characterized by curing simultaneously.