Solid tempera and method for manufacturing same

Abstract

The present invention relates to a solid tempera and to the method for manufacturing the same, which includes a dispersion of resin having a concentration value of 10% to 70%, sodium stearate having a concentration of 10% to 20%, glycerine having a concentration value of 4% to 20%, water having a concentration of 7% to 50%, a pigment having a concentration value of 5% to 15%, an anti-foaming agent having a concentration of 1% to 3%, and a biocide having a concentration of 0.10% to 0.4%, the above concentration values relating to the final product. The tempera of the invention is used for painting or drawing on a substrate such as paper, Bristol board, wood or cardboard, being applied directly to said substrates without having to add water.

Claims

1. A solid tempera, to be used for painting or drawing on paper, Bristol board, wood, cardboard, for direct application without the need to add water, wherein it comprises: a resin with a concentration between 10% and 70% in weight of the final product, selected within the group formed by: polyvinyl pyrrolidone k80-k90, wherein k refers to the molecular weight of the polymer, polyvinylalcohol preferably with an hydrolysis degree/99 (such as 17/99-65/99), and a polyvinylacetal resin, and sodium stearate with a concentration between 10% and 20%, glycerine with a concentration between 4% and 20%, water with a concentration between 7% and 50%, a pigment with a concentration between 5% and 15%, an anti-foaming agent with a concentration between 1% and 3%, and finally a biocide with a concentration between 0.10% and 0.40%, all of the concentrations being referred to the final product, and wherein the final product comprises the components in an homogeneous mix of two microphases, thereby, in use, a microphone of resin sticks to the substrate depositing a gelatinous layer that absorbs the pigment of the other immediately adjacent microphone, thus creating a film covering with uniform color and high covering capacity, a relief, and a 3D effect.

2. The solid tempera, according to claim 1, wherein the pigment may be an organic, inorganic or metallic pigment.

3. The solid tempera, according to claim 1, wherein the anti-foaming agent is selected within the group consisting in silicone water dispersions.

4. The solid tempera, according to claim 1, wherein the biocide is selected within the group comprising methyl or ethyl para-hydroxybenzoates (parabene).

5. The solid tempera, according to claim 1, wherein the biocide is a combination of benzisothiazolone and phenoxyethanol.

6. The solid tempera, according to claim 1, wherein it comprises polyvinylacetal with a concentration of 60%, glycerine with a concentration of 7%, sodium stearate with a concentration of 12%, water with a concentration of 10% and pigment with a concentration of 9%.

7. A method for manufacturing solid tempera, according to claim 1, characterized by the following steps: ito provide a mix A comprising pigments, sodium stearate, glycerine and water; iito provide a mix B comprising a concentrated solution of resin in water, wherein the resin is selected within the group formed by polyvinyl pyrrolidone, polyvinylalcohol, polyvinylacetal; iiito heat the two solutions A and B to a temperature comprised within 60-90 C.; ivto mix by simultaneous addition the solutions A and B obtained in the steps i and ii, within a mould or container, obtaining the final mix C, containing solution A with a concentration of (40-60%) and solution B also with a concentration of (40-60%); vsolidification of the resulting mix C within the containers to form a dimensionally stable solid tempera, that under a low mechanical effort, has the capacity to easily disperse on a surface or substrate such as paper, Bristol board, wood or cardboard.

8. The method, according to claim 7, wherein the mix of the solutions A and B in the mould or container is carried out within a period of time comprised between 0.5 seconds and 2 seconds, so that the resulting mixing velocity prevents the total homogenization of both solutions A and B which are mixed together and at the same time prevents the total homogenization of the sodium stearate within the final mix.

9. The method, according to claim 7, wherein the solidification step of the mix is carried out during a period of time of 5 to 10 seconds, submitting the packaged mix C to a flow of cool air under a temperature comprised between 10 C. and 20 C., so that the solidifying prevents the total homogenization of both solutions A and B which are mixed.

Description

DESCRIPTION OF THE DRAWING

(1) FIG. 1 corresponds to a diagrammatic illustration showing the step of mixing solutions A and B into the container.

PREFERRED EMBODIMENT OF THE INVENTION

(2) As above mentioned a solid tempera according to the present invention, to be used for painting or drawing on paper, Bristol board, wood, cardboard, is to be directly applied without the need to add water, comprising a resin with a concentration between 10% and 25% of solid resin, or 40-70% of resin in dispersion of 40-50% of solid matter, sodium stearate with a concentration between 10% and 20%, glycerine with a concentration between 4% and 20%, water with a concentration between 7% and 50%, pigment with a concentration between 5% and 15%, anti-foaming agent with a concentration between 1% and 3%, and finally a biocide with a concentration between 0.10% and 0.40%, said concentration amounts being referred to the final product.

(3) The method for the manufacture of the solid tempera explained in the examples was carried out according the above explained new method, consisting in the preparation of a mix A comprising the quantities of pigment, sodium stearate, wetting agents, glycerine and water needed for the formulation of the final product of the solid tempera. At the same time, the mix B is prepared comprising a concentrated solution of the specific resin in water, wherein the resin is selected within the group formed by: polyvinyl pyrrolidone, polyvinylalcohol, alkali soluble acrylics, vinyl styrene, polyvinylacetal. Both solutions are preferably prepared in containers with stirring, having heating means.

(4) After the preparation of the two solutions A and B, these are heated up to a temperature of 70 C. After reaching said temperature the solutions A and B are mixed by means of a simultaneous mixing action within a mould or container, so as to obtain a final mix C containing a solution A with a concentration of 40% to 60% and solution B with a concentration also of 40%60%.

(5) The mixing of the solutions A and B within the mould or container has an especial importance in the performance of the invention as said mixing operation has to be carried out at a very fast speed, preferably within a period of time of less than 4 seconds, so that said velocity prevents the total homogenization of both solutions A and B to be mixed, permitting the sufficient dissolution of the sodium stearate.

(6) Preferably, the mixing of said solutions A and B to the above mentioned speed has to be carried out so that a certain turbulence is created to provoke the portions effectively mixed between solutions A and B to be sufficiently small to obtain the sufficient heterogeneity between the solutions which are mixed (mix of microphases). In this connection, in FIG. 1 is shown the way in which solutions A and B have to be mixed to obtain the adequate results in the product of the invention. As is to be observed, a dispensing container (1) with the solution A and a dispensing containers (2) with solution B are provided, said dispensers pouring the respective solutions to the above mentioned velocities into container (3), forming the mix or solution C.

(7) In this case, the container is the same as the element to be used for the final application of the product.

(8) After finishing the mixing operation of solutions A and B, the cooling down of the product and its solidification is carried out obtaining the resulting mix C, forming the solid tempera. The solidification of the mix is carried out within a period of time of 5 seconds, submitting the mix C already packaged to a cold air flow with a temperature between 10 C. and 20 C., so that a fast solidification may be obtained, to prevent the total homogenization of both solutions A and B after the mixing operation.

(9) In the following, some compositions are shown as examples corresponding to the scope of the invention.

(10) The solid tempera compositions of the following examples were prepared according to the method of manufacture of the invention.

Example 1

(11) TABLE-US-00001 Polyvinylpyrrolidone K-90 20% Glycerine 7% Sodium stearate 12% Water 50% Red pigment dispersion 9% Silicone dispersion (10%) 1.8% Methylparabene 0.2%

Example 2

(12) TABLE-US-00002 Polyvinyl alcohol 17/99 10% Glycerine 7% Sodium stearate 12% Water 60% Red pigment dispersion 9% Silicone dispersion (10%) 1.8% Methylparabene 0.2%

Example 3

(13) TABLE-US-00003 Polyvinylacetal (13%) 60% Glycerine 7% Sodium stearate 12% Water 10% Red pigment dispersion 9% Silicone dispersion (10%) 1.8% Methylparabene 0.2%

(14) In Example 3, the polyvinylacetal is obtained by the reaction between polyvinyl alcohol (PVA) and a certain rate of formaldehyde or acetaldehyde. The reaction is to be carried out in very acid conditions with pH near to pH 2, under heating with a temperature near 90 C., during a time of 4 hours. In this case, for the formation of the polyvinylacetal the composition has 86.5% of water, 10% of polyvinylalcohol, 0.5% of HCl (conc. to 37%), and 3% of acetaldehyde.

(15) An embodiment of a solid tempera formulated with a composition as shown in the above examples of embodiment and carried out with the manufacturing method of the invention permits to obtain a sufficiently solid product dimensionally stable within a given range of temperatures, which permits to maintain its shape and its stable conservation after its manufacture and packaging. Said product is adequate to be applied on substrates such as paper, Bristol board, wood, cardboard, being directly applied without the need of adding water.

(16) Determination of Abrasion of the Solid Tempera by Weighing of the Tempera Tube.

(17) As a comparison, tests were carried out to compare the application on a substrate of solid temperas manufactured by means of the method of the invention and other temperas manufactured by the traditional method.

(18) The traditional method as mentioned hereabove, consisted usually in the hot mixing under stirring of all the components of the tempera in order to successively deposit the tempera into the packaging containers.

(19) Said test consisted in the evaluation of the abrasion of the solid tempera by weighing the tempera tube, determining the amount of solid tempera applied on a substrate after application of a weight on said tempera paste.

(20) The test was carried out according to the following process: a) Preparation of 4 paper strips of 305 cm with a weight of 80 g/m.sup.2. b) Numbering and weighing separately in a precision balance, 4 tubes of solid tempera including the closing cap (weight=P1). c) To arrange one of the strips on a DIN A4 sheet secured on the work table by means of adhesive tape. d) To make the end of the tempera to protrude 5 mm, rotating the base of the tube. e) To cut the tempera to the level of the tube edge with a knife. f) To make the new end of the tempera to protrude 15 mm, rotating the base of the tube. g) To introduce the tempera tube from the bottom part of the void cylinder of the tool to carry out abrasions, so that the paste contacts the paper strips. h) To introduce the cylindrical weight of 1.5 kg by the top end of the void cylinder laying the same carefully on the inverted paste tube. i) To make the paper strip to slide from one end to the other pulling with both hands during 15 seconds, repeating the process in the contrary direction in case of carrying out a test with 2 runs. j) To weigh the used tube (weight=P2). k) To evaluate the weight of the impregnated tempera (weight=P1P2). l) To express the results in mg of the impregnated tempera.

(21) The equipment and reagents used in said test were a precision balance with a precision of 0.001 g, 80 g/m.sup.2 DIN A4 paper, tooling to make the abrasions, a 1.5 kg weight and the product to be tested.

(22) The test was carried out with three solid temperas prepared according to the method described in this invention, comprising a composition such as shown in Example 3 of the description, changing for each test the type of pigment used within the group of red, yellow and blue pigments but maintaining the same pigment concentration. For the three tempera manufactured according to the method of the prior art, the type of pigment was changed likewise.

(23) The results obtained in the test are as shown in Table 1.

(24) TABLE-US-00004 TABLE 1 Amount of Amount of tempera impreg- tempera impreg- nated in one run nated in two runs mg mg Tempera (traditional 39 62 method) Yellow pigment Tempera (method 49 75 according to the invention) Yellow pigment Tempera (traditional 37 61 method) Blue pigment Tempera (method 45 72 according to the invention) Blue pigment Tempera (traditional 36 64 method) Red pigment Tempera (method 46 76 according to the invention) Red pigment

(25) From the table showing the results is to be derived that using the solid tempera manufactured according to the method of the invention on a substrate, a greater amount of product will be impregnated on said substrate in comparison to the use of a tempera manufactured by the traditional methods, this demonstrating the better application of the tempera of the invention, its higher covering capacity and its easy dispersibility on said substrates. This fact is also evidenced in case of using various types of pigments in the manufacture of the tempera.

(26) Therefore, the solid tempera of the invention permits to obtain a product allowing a satisfactory dispersibility, of the film obtained with high covering capacity and with the possibility to obtain different hues of colour by the superposition of layers of material, which dry very rapidly and that in spite of being solid, require a low mechanical effort to be dispersed on said substrates.

(27) After having sufficiently described the present invention in relation with the examples shown, it is easy to understand that multiple modifications could be carried out in the same in the details deemed convenient, provided that the essentials of the invention, as defined in the following claims are not altered.