JP2000007977A - Moisture proof coating material for laminated paper model, process for applying moisture proof coating material to laminated paper model, and moisture proof coated laminated paper model - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the blistering due to moisture absorption of a laminated paper model formed by adhesively laminating multi-ply paper sheets. SOLUTION: A moisture proof coating material for a laminated paper model is produced by dissolving a vinylidene chloride resin with an organic solvent obtained by mixing an aromatic solvent and a polar solvent and adjusting a solubility in the vinylidene chloride resin and a loss by evaporation in the application of the coating material. In the process for applying the moisture proof coating material to the laminated paper model, the priming step of applying an ultraviolet-curable coating material in mixture with a pigment to the surface of the laminated paper model 10 and curing it by ultraviolet irradiation and thereafter polishing the surface to smooth it is repeated a plurality of times to form a primer coat 15 on the surface of the laminated paper model. Then, the moisture proof coating material is applied on the primer coat and dried to form a moisture proof coating layer 16. A moisture proof coated laminated paper model is obtained by forming a moisture proof coating layer made of a film of a vinylidene chloride resin on the surface of the laminated paper model.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moisture-resistant paint for improving the moisture resistance of a paper laminate model, a method of coating a paper laminate model with the moisture-resistant paint, and a paper coated with the moisture-resistant paint. Related to the laminated model.

[0002]

2. Description of the Related Art As a master model for mold production or a wooden mold substitute for a casting, a paper laminated model in which a large number of paper sheets are laminated and bonded may be used. In such a paper lamination model, paper sheets coated on the back surface with an adhesive that is melted by heating to generate an adhesive force are stacked one by one, and heated by a hot roller that moves on the upper surface each time one paper sheet is fed. At the same time, the sheet is pressed and adhered on the laminated body laminated so far, and the paper sheet just adhered is cut by a laser beam along the contour shape (slice data) of the model corresponding to the height position. It is formed by doing.

[0003]

The paper sheet used for such a paper lamination model usually contains about 7 to 8% of water, but is heated and pressed by a hot roller (for example, 300 ° C.) during molding. Therefore, the water content immediately after molding drops to about 4%. If this is left in a normal room, the moisture in the air is absorbed and the water content increases. On the other hand, the paper sheet is squeezed and dried in the papermaking process by passing water between heater rollers. At that time, the fibers of the paper are compressed in the thickness direction and crushed. For this reason, in the paper lamination model as described above, when the water content increases from a state in which the water content is low immediately after molding, it expands accordingly, particularly in the laminating direction which is the thickness direction of the paper. As an example of the amount of expansion (saturation value), if the relative humidity in the air left unattended is 4
2 per 100mm in a normal room of 0-60%
mm and 10% when the relative humidity is 90%.
It is about 9 mm per 0 mm.

[0004] In order to reduce or delay such expansion due to moisture absorption, a nitrocellulose lacquer is brush-painted on a paper laminated model immediately after molding and dried, or an ultraviolet-curable paint is sprayed and applied and cured by ultraviolet irradiation. Then, a film is formed on the surface. However, such a coating is microscopically porous and has a low gas barrier property, so that sufficient moisture resistance cannot be imparted to a paper laminated model. For example, a line A in FIG. 3 is a rectangular parallelepiped paper laminate model 1 having a width W of 30 mm, a length L of 100 mm, and a height H of 100 mm as shown in FIG.
On the surface of No. 0, an undercoating step of repeating the undercoating step of spraying and applying an acrylate ultraviolet curable paint containing a pigment and curing the same by irradiating ultraviolet light, and then polishing and smoothing the surface to form an undercoat paint layer, is performed. In the case where the acrylate UV curable paint not containing a pigment is further spray-coated and a top coat layer is formed and left in a normal room, it shows one measurement example of the height increase with respect to the number of elapsed days. An expansion of 0.2 mm occurs after 15 days and 1.39 mm after 70 days. The line C in FIG. 4 shows a measurement example of the height increase amount with respect to the number of elapsed days in the same case as the above example except that the width W of the paper laminate model 10 is 15 mm. 0.2mm, 2
After one day, it has expanded by 1.49 mm. The intrusion of moisture in the air into the paper laminate model 10 is mainly performed from the cut direction of the paper sheet P, and the penetration from the thickness direction is small. The amount of increase is large.

As described above, the improvement of the moisture resistance by the prior art coating is small, and the paper laminated model expands in the laminating direction and changes its size, so that it can be used as a master model or a wooden mold substitute (lifetime). There is a problem that is short. As a means for solving such a problem, for example, the surface of the paper laminated model is coated with a film having a good gas barrier property such as vinylidene chloride resin (copolymer of vinylidene chloride and vinyl chloride, vinyl acetate, acrylonitrile, etc.). Can be considered. However, there is only a water-soluble emulsion type paint using vinylidene chloride resin, and in such a case, the moisture in the water-soluble emulsion is contained in the paper laminate model before the paper laminate model is coated with the vinylidene chloride resin film. Because of the absorption, the original purpose of preventing or delaying the dimensional change by keeping the water content unchanged cannot be achieved. An object of the present invention is to solve each of these problems.

[0006]

SUMMARY OF THE INVENTION A moisture-resistant paint for a paper-laminated model according to the present invention is obtained by mixing a vinylidene chloride resin with an aromatic solvent and a polar solvent, and dissolving the vinylidene chloride resin with the vinylidene chloride resin and evaporating during coating. Characterized by being dissolved in an organic solvent prepared by adjusting The organic solvent in the applied moisture-resistant paint evaporates in a short time, and even if it is absorbed by the paper sheet of the paper laminate model, it hardly expands.Therefore, a gas barrier is formed on the surface without expanding the paper laminate model. Thus, a moisture-resistant coating made of vinylidene chloride resin having high properties is formed.

According to the method of the present invention for applying a moisture-resistant coating to a paper laminate model, an ultraviolet curing paint is applied to the surface of a paper laminate model formed by laminating and bonding a large number of paper sheets, and this is cured by irradiation with ultraviolet light to form an undercoat layer. After the formation, a moisture-resistant paint obtained by dissolving a vinylidene chloride resin with an organic solvent is applied on the undercoat layer and dried to form a moisture-resistant paint layer. The vinylidene chloride resin having a high gas barrier property forms a moisture-resistant coating layer, and the undercoat coating layer reduces the absorption of the organic solvent in the moisture-resistant coating into the paper laminate model when forming the moisture-resistant coating layer.

The undercoating layer in the moisture-resistant coating method of the paper laminated model described in the preceding paragraph is applied to the surface of the paper laminated model by applying an ultraviolet curable paint mixed with a pigment, and after curing this by irradiating ultraviolet rays, polishing the surface. It is preferable to form it by repeating the smoothing undercoating step a plurality of times.

Further, the paper laminate model coated with moisture resistance according to the present invention is characterized in that a moisture resistant paint layer made of a vinylidene chloride resin film is formed on the surface of a paper laminate model formed by laminating and bonding many paper sheets. It is assumed that. The moisture-resistant coating layer forms a moisture-resistant coating.

The moisture-resistant coating layer of the paper-laminated model coated with moisture-resistant coating described in the preceding paragraph is preferably formed on an undercoat coating layer obtained by curing an ultraviolet-curable coating applied to the surface of the paper-laminated model by irradiation with ultraviolet rays. .

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 1, a paper stack model 10 to which the present invention is applied is a model in which a large number of paper sheets P are bonded, and each time one paper sheet P is bonded, a model corresponding to the height position is provided. Formed by cutting with a laser beam along the contour shape of. First, the surface of the paper laminated model 10 is
5 and a moisture-resistant coating layer 16 is further applied thereon.

In order to form the undercoating layer 15, an acrylate ultraviolet curable paint containing a volume pigment is first sprayed onto the surface of the paper laminate model 10 by spraying, and then irradiated with ultraviolet light to cure it. Polish with sandpaper so that the surface becomes smooth. As shown in the figure, the surface of the paper laminate model 10 has fine step-like irregularities due to the thickness of the paper sheet P, but by repeating the undercoating step including smooth polishing with sandpaper as described above three times, The surface of the undercoating layer 15 is a smooth surface without irregularities. Paper sheet P constituting the paper stack model 10
Hardly swells immediately due to organic solvents (swells when exposed to organic solvents for a long time), but acrylate UV-curable coatings do not contain such organic solvents and do not evaporate and harden due to UV irradiation Therefore, such a slight expansion does not give the paper laminated model 10.

The moisture-resistant paint used to form the moisture-resistant coating layer 16 is a vinylidene chloride organic solvent paint.
This is a vinylidene chloride organic solvent paint obtained by dissolving vinylidene chloride resin (a copolymer of vinylidene chloride with vinyl chloride, vinyl acetate, and acrylonitrile) in an organic solvent obtained by mixing an aromatic solvent and a polar solvent. An example of the mixing ratio is as follows. 20% by weight of vinylidene chloride resin 20% by weight of aromatic solvent 60% by weight of polar solvent Each individual solvent is adjusted so as to obtain necessary solubility in vinylidene chloride and evaporability suitable for spray coating. Shall be. On the undercoat layer 15 formed on the surface of the paper laminate model 10 as described above,
The above-mentioned vinylidene chloride organic solvent paint is sprayed and applied, sprayed in a thermostat, and dried with hot air of 50 ° C. for 30 minutes, whereby the moisture-resistant coating layer 16 made of vinylidene chloride resin is undercoated. Formed on layer 15.

Since the moisture-resistant coating layer 16 made of a vinylidene chloride resin coating has a high gas barrier property, the paper laminated model 10 covered with such a moisture-resistant coating layer 16 has an expansion due to moisture absorption when left indoors. Become smaller. Next, this will be described in comparison with the prior art. Line B in FIG.
Forms an undercoating layer 15 by repeating the undercoating step with the acrylate ultraviolet curable paint containing pigment three times on the surface of the rectangular parallelepiped paper laminate model 10 having the same dimensions as the case of the line A in FIG. This shows a measurement example of the amount of height increase with respect to the number of elapsed days when the moisture resistant coating layer 16 made of a vinylidene chloride organic solvent paint is formed thereon and left in a normal room. In this case, the height increase is 0.2 mm after 37 days, and 0.37 after 70 days.
mm, the number of days required to increase by 0.2 mm is 2.5 times as compared with the line A in the prior art described above, and is 7 times.
The height increase after 0 days has decreased by 73%. In addition,
The measurement of the line A and the line B are performed simultaneously and in the same room. Further, the line C in FIG.
It shows a measurement example of the height increase amount with respect to the number of elapsed days in the same case as the above example except for the point of mm.
It is 0.2 mm after 21 days and 0.25 mm after 21 days.
The number of days to increase by 2 mm is 4.7 times, and the height increase after 21 days has decreased by 83%.

As shown in the above embodiment, the paper laminate model 10 covered with the undercoating layer 15 and the moisture-resistant coating layer 16 as described above, when left in a normal room,
The number of days required to reach a certain predetermined height increase increases, and the height increase after a certain predetermined number of days decreases. Therefore, it is possible to lengthen the use period of the paper stack model 10 in an application requiring accuracy. it can.

The organic solvent in the vinylidene chloride organic solvent paint may slightly expand the paper laminate model 10 if absorbed by the paper laminate model 10. In this embodiment, such an organic solvent is used. Is not blocked by the undercoating layer 15 and is not absorbed by the paper laminate model 10 and evaporates quickly after application, so that the paper laminate model 10 is not likely to expand.
The dimensional accuracy of 0 can be further improved. However, since the expansion by the organic solvent from the vinylidene chloride organic solvent paint is slight and has little influence, the present invention can be carried out without the undercoat layer 15 made of the ultraviolet curable paint.

In the above embodiment, the undercoating layer 15 is formed by repeating the undercoating step using the ultraviolet curable paint mixed with the pigment a plurality of times. Paint layer 15
, And the shape of the surface of the paper laminate model covered with the moisture-resistant coating layer 16 is also smoothed.

[0018]

According to the moisture-resistant paint for a paper laminate model of the present invention, the paper laminate model hardly expands at the time of painting, and a moisture-resistant coating of a vinylidene chloride resin having a high gas barrier property is formed on its surface. Therefore, it is possible to prolong the use period of the paper lamination model in applications requiring high dimensional accuracy.

According to the moisture-resistant coating method for a paper-laminated model according to the present invention, since a moisture-resistant coating layer made of vinylidene chloride resin having high gas barrier properties is formed on the surface of the paper-laminated model, high dimensional accuracy is required. The paper laminate model can be used for a longer period of time, and the absorption of organic solvents into the paper laminate model when forming a moisture-resistant coating layer is reduced, which reduces the expansion of the paper laminate model. The dimensional accuracy of the model can be further improved. In this case, according to the method in which the undercoating layer is formed by repeating the undercoating step with the ultraviolet curable paint containing the pigment a plurality of times, some irregularities generated on the surface of the paper laminate model are smoothed by the undercoating layer. Therefore, the shape of the surface of the paper laminate model covered with the moisture-resistant coating layer is also smoothed.

Further, according to the paper laminate model coated with moisture resistance according to the present invention, since the moisture resistant paint layer made of vinylidene chloride resin having high gas barrier properties is formed on the surface of the paper laminate model, high dimensional accuracy is required. It is possible to lengthen the use period of the paper laminate model in the intended use. In this case, according to the one in which the moisture-resistant coating layer is formed on the undercoat coating layer made of the ultraviolet-curing paint, even when the moisture-resistant coating layer is formed with the vinylidene chloride organic solvent paint, the paper lamination model Since the absorption of the organic solvent is reduced and the expansion of the paper laminate model is also reduced, the dimensional accuracy of the paper laminate model can be further improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a paper laminate model coated with moisture resistance according to the present invention.

FIG. 2 is an explanatory diagram of dimensions and shapes of a paper lamination model used in a measurement example described below.

FIG. 3 is a diagram illustrating a measurement example of a height increase amount of a paper stack model with respect to an elapsed number of days according to an embodiment of the present invention and an example of the related art.

FIG. 4 is a diagram showing a measurement example similar to FIG. 3 in another embodiment of the present invention and another example of the prior art.

[Explanation of symbols]

10: paper laminated model, 15: undercoating layer, 16: moisture-resistant coating layer, P: paper sheet.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J038 CD081 JA03 KA06 LA06 NA04 NA23 PA12 PA18 PB06 PC10 4L055 AG67 AH02 AH37 AH48 AJ01 AJ02 AJ04 BE09 BE20 GA47

Claims (5)

[Claims] 1. A paper characterized in that a vinylidene chloride resin is dissolved in an organic solvent obtained by mixing an aromatic solvent and a polar solvent to adjust solubility in the vinylidene chloride resin and evaporation during coating. Moisture resistant paint for laminated models. 2. An ultraviolet curable paint is applied to the surface of a paper laminated model formed by laminating and adhering a large number of paper sheets, and this is cured by irradiation with ultraviolet light to form an undercoating layer. Then, the vinylidene chloride resin is washed with an organic solvent. A moisture-resistant coating method for a paper-laminated model, comprising applying a dissolved moisture-resistant coating on the undercoat layer and drying it to form a moisture-resistant coating layer. 3. The undercoating layer includes a plurality of undercoating steps of applying an ultraviolet curable paint mixed with a pigment to the surface of the paper laminate model, curing it by irradiating ultraviolet light, and then polishing and smoothing the surface. The method according to claim 2, wherein the method is performed by repeating the process a number of times. 4. A paper laminate model coated with moisture resistance, wherein a moisture resistant paint layer made of a vinylidene chloride resin film is formed on the surface of a paper laminate model formed by laminating and adhering a large number of paper sheets. 5. The moisture-resistant coating layer is formed on an undercoating layer formed by curing an ultraviolet-curable coating applied to the surface of the paper laminate model by irradiation with ultraviolet light. Moisture resistant painted paper laminate model.