METHOD OF FORMING PATTERNS ON CONCRETE SURFACE AND DECORATION MAT USED FOR THE METHOD

Abstract: In the decoration mat of this invention, a large number of colored particles are distributed on a rugged pattern transfer surface through an adhesive layer the bonding power of which decreases upon water absorption. A method of forming a pattern on a concrete surface according to this invention comprises pouring a concrete material using the rugged pattern transfer surface of the decoration mat as a contact surface with the concrete surface, reducing the bonding power of the adhesive layer by the moisture of the concrete material, transferring and burying the colored particles into the concrete surface, and forming the concrete surface into the rugged pattern surface by the transfer of the rugged pattern transfer surface. In the method of this invention, the bonding power of the adhesive layer is reduced by the moisture of the concrete material during aging and curing after pouring, and the colored particles retained by the adhesive layer are transferred to, and buried into, the surface layer of the concrete material. Accordingly, colors of natural color tones can be expressed on the surface layer of the concrete molded article. Since the colored particles do not undergo discoloration, fading and deterioration, a rugged pattern retaining high durability for a long time can be obtained.

Description: The present invention relates to a method of patterning a concrete surface and to a pattern transfer mat for use in the method (see f.i. US-A-3,737,511). Heretofore the following procedure has been employed for producing an attractive three-dimensional pattern on a concrete surface. First, a mat (a pattern transfer mat) 10, such as the one illustrated in Fig. 4, is provided. This transfer mat 10 is composed of a rigid urethane foam and has on one side an effective transfer surface 13 formed with an aesthetic three-dimensional pattern and on the other side a flat back surface 14. This transfer mat 10 has foam 11 inside and an integral skin layer 12 on the surface. This integral skin layer 12 is substantially free of air cells or has very little fine air cells, and densely concentrated compared with the foam layer 11, and is smooth. The pattern transfer surface 13 is formed on this smooth surface of the integral skin layer 12. At the job site or in the field, a release agent is applied to the transfer surface 13 of the transfer mat 10, and the transfer mat 10 and a casting form 16 are positioned face-to-face as shown in Fig. 5. Then, the side openings and bottom openings (not shown) between the form 16 and the mat 10 are closed with boards and the like and concrete material 15 is poured from the top opening. The reference number 17 indicates a board. The concrete material 15 is then allowed to harden to a concrete board or structure 18. As shown in Fig. 6, the concrete structure 18 is then detached from the mat 10. The surface of the concrete 18 thus obtained has the three-dimensional pattern of the mat 10 replicated on its surface. Finally this sculptured concrete surface is finished, for example by spraying with a suitable coating composition, to give a natural-looking surface. However, since the coating material used in the above process is usually an organic composition and the organic coating film tends to discolor, fade or undergo degradation with time, the surface of the concrete is not as durable as the surface of, for example, masonry of inorganic material (such as natural rock). Moreover, it is necessary to recoat the surface at certain intervals and the cost of maintenance including this "refreshing" work is substantial. It has been desired to provide a method of patterning a concrete surface which is capable of producing a natural-looking pattern or texture or the like on a concrete surface, durable for a long term and not needing to be recoated, and also to provide a pattern transfer mat for use in such a method. SUMMARY OF THE INVENTION In a first aspect, the invention provides a method of patterning a concrete surface comprising preparing a pattern transfer mat including a plurality of aesthetic grains distributed on a surface thereof (hereinafter referred to sometimes as the effective surface) held thereon by an adhesive layer the binding force of which is decreased on absorption of water, casing concrete material against the effective surface of the mat, decreasing the binding force of the adhesive layer by absorption of water from the concrete material, thereby to transfer the aesthetic grains onto the concrete surface and embed them therein, and forming a three-dimensional pattern on the concrete surface by the effective surface. In a second aspect, the invention relates to a pattern transfer mat comprising a plurality of aesthetic grains held on an effective transfer surface of the mat formed with an aesthetic three-dimensional pattern by an adhesive layer the binding force of which is decreased by absorption of water. During curing and hardening after casting the concrete material as mentioned above, the aesthetic grains held in the adhesive layer are transferred into the surface layer of the concrete material which is hardening and are embedded partially or completely by the decrease of the binding force of the adhesive layer by absorption of water from the concrete material. In this way, a plurality of aesthetic grains are embedded in the surface of a patterned concrete product, whereby colors such as natural-looking color and the like appear on the surface, and the surface becomes natural-looking by transfer of a three-dimensional pattern onto the surface. The aesthetic grains embedded in the surface layer do not tend to discolor or fade or undergo degradation with time, resulting in excellent long-term durability. Therefore, recoating and the like at intervals is not necessary, in contrast to the prior art techniques resulting in a decrease in the cost of maintenance. A preferred embodiment of the invention is now described in further detail. Rigid polyurethane foam resin is employed as the material for the pattern transfer mat, whereby the mat has sufficient mechanical strength to withstand the concrete material poured against it during casting. The adhesive layer is formed by coating adhesive or binder onto the effective surface of the mat. A water-soluble adhesive such as methylcellulose or polyvinyl alcohol is the preferred adhesive. The resulting thickness of the coated film thereby is preferably 0.1 to 5 mm. The aesthetic grains are crushed colorful natural rocks. The following methods are used for distributing a plurality of aesthetic grains onto the adhesive layer, adhesion of a plurality of aesthetic grains to the adhesive layer by pressure-spray; distribution of a plurality of aesthetic grains to the adhesive layer, embedding them into the layer by a press or the like, and anchoring thereof; or a combination of both these methods. Using crushed colorful natural rocks as the aesthetic grains, the mean diameter (A) of such aesthetic grains is not greater than 10 mm and the grain size distribution is such that grains within the range of 0 <A ≤1 mm account for 70 to 30% (by weight; the same applies hereinafter), those in the range of 1 <A ≤5 mm account for 30 to 70%, and those in the range of 5 <A ≤10 mm account for 0 to 10%. Further, from one to seven kinds of coloring material are preferably used. The invention will be further described, by way of example, with reference to the drawings, in which: Fig. 1 is a schematic view showing a pattern transfer mat according to an embodiment of the invention; Fig. 2 is a schematic view showing a pattern transfer method using the pattern transfer mat of Fig. 1; Fig. 3 is a schematic view showing the step of parting the product concrete board; Fig. 4 is a schematic view showing a conventional pattern transfer mat; Fig. 5 is a schematic view showing a pattern transfer method using the conventional pattern transfer mat of Fig. 4; and Fig. 6 is a schematic view showing the step of parting the product concrete board. EXAMPLE Referring to Fig. 1 which shows a pattern transfer mat embodying the invention, the pattern transfer mat 1 is made of rigid polyurethane foam. Like the prior art mat, it consists of a foam core layer 2 and an integral skin layer 3 on its surface. The three-dimensional pattern surface 4 of this pattern transfer mat 1 is a smooth profiled surface, while the opposite surface is a flat back surface 7. The surface 4 is first coated with a water-soluble methylcellulose adhesive to form a binding layer 5 having a thickness of 0.1 - 5 mm. To this binding layer, a multiplicity of colorful natural rock grains 6 are bonded by a pressure-spray method. Using the above pattern transfer mat 1, concrete material 15 is cast and allowed to cure as illustrated in Fig. 2. This step is the same as the corresponding step with known transfer mats, shown in Fig. 5. Then, as shown in Fig. 3, the pattern transfer mat 1 is detached from the concrete structure 18. This step is the same as the corresponding step with known transfer mats, shown in Fig. 6. The resulting concrete structure 18 has a marble-like colored surface pattern on the aesthetic three-dimensional pattern surface 8 in which natural rock aesthetic grains 6 are distributed.

Claims: A method of patterning a concrete surface comprising: preparing a pattern transfer mat (1) including a plurality of aesthetic grains (6) on an undulating surface (4) thereof, the said surface having a three-dimensional pattern thereon and the said grains being held on the surface by an adhesive (5), the binding strength of which decreases on absorption of water; and casting concrete material (15) against the said surface of the mat, the binding strength of the adhesive decreasing by absorption of water from the concrete material thereby to transfer the aesthetic grains onto the concrete surface (18) and embed them therein to form a three dimensional pattern on the concrete surface by the said surface of the mat; characterised by using crushed colorful natural rocks, wherein the mean diameter, A, of the aesthetic grains (6) is not greater than 10mm and the grain size distribution is 0 < A ≤ 1 mm = 30-70% by weight; 1 < A ≤ 5 mm = 70-30% by weight; and 5 < A ≤ 10 mm = 0-10% by weight; and in which the aesthetic grains (6) are pressure-sprayed onto the surface (4) of the pattern transfer mat (1) which is carrying a layer of adhesive (5) and/or dispersed on said surface before being embedded into the adhesive layer by a press to anchor them thereto. A pattern transfer mat (1) comprising a plurality of aesthetic grains (6) held on an undulating transfer surface (4) of the mat by an adhesive (5), the binding strength of which decreases on absorption of water, the transfer surface having a three-dimensional pattern thereon; wherein the mean diameter, A, of the aesthetic grains (6) is not greater than 10mm and the grain size distribution is 0 < A ≤ 1 mm = 30-70% by weight; 1 < A ≤ 5 mm = 70-30% by weight; and 5 < A ≤ 10 mm = 0-10% by weight; and in which the aesthetic grains (6) were pressure-sprayed onto the transfer surface (4) which carries a layer of adhesive (5) and/or were dispersed on said surface before being embedding into the adhesive layer by a press to anchor them thereto.

Inventors: IWAYA NOBUO, IWAYA, NOBUO
Applicants: TOKAI RUBBER IND LTD, TOKAI RUBBER INDUSTRIES, LTD.
Application year: 1993
Main classification: B28B1
IPC codes: B28B1, E04G9, B28B19, B28B7, B44C1, E04F13