JP6094498B2 - Mold for resin molding - Google Patents

Description

The present invention relates to a resin molding die.

  Various resin molded products are molded by injection molding, blow molding, vacuum molding, or the like. The surface of these resin molded articles generally has a gloss. Therefore, when it is necessary to reduce the glossiness of the surface, for example, matte coating is performed. There is also a method of forming a fine unevenness on the surface of a resin molded product by forming fine unevenness on the mold surface of a resin molding die, that is, a method for obtaining a matte surface with low glossiness. Are known. Such roughening of the mold surface can be performed by sandblasting or chemical etching. According to this method, the matte coating on the resin molded product becomes unnecessary.

  Patent Document 1 discloses a chemical etching method for a resin molding die for obtaining a resin molded product having various uneven patterns on the surface, although matte is not the purpose. In this method, the resist resin is attached to the mold surface, and the process of removing the resist resin by etching the mold surface exposed between the resist resins is repeated a plurality of times. It is described that a Fuji-shaped convex portion is formed on the mold surface by narrowing the width.

JP-A-11-245234

  By the way, regarding the roughening of the mold surface of the resin molding die, making the mold surface uneven can be advantageous for matting the surface of the resulting resin molded product, but the scratch resistance (scratch characteristics) is reduced. There is a problem of doing. This is because, when the surface of the resin molded product is scratched, the smaller the convex portion, the easier it is to cut or plastic deformation. Thus, low gloss and improved scratch resistance are contradictory requirements from the viewpoint of roughening the mold surface.

  Further, when there is a glass surface in the vicinity of the resin molded product, an image of the resin molded product may be reflected on the glass surface. Depending on the place of use of the resin molded product, it is desired to suppress this reflection. For example, if a resin interior is reflected on the windshield or meter panel of an automobile, the visibility is lowered. In general, the rougher the surface of the resin molded product, the stronger the contrast between the concave and convex portions, and the more likely it is to reflect.

  An object of the present invention is to reduce gloss and suppress reflection without impairing scratch resistance.

  In order to solve the above-described problems, the present invention forms fine irregularities on the mold surface of a resin molding die, and further finer irregularities are formed on at least the convex surface of the fine irregularities.

The mold for resin molding presented here has fine irregularities for roughening the surface of the resin molded product to be molded on the mold surface, and resin molding to be molded on at least the convex surface of the fine irregularities. There are even finer irregularities to roughen the surface of the product,
The uneven height of the fine unevenness is 1 μm to 30 μm, and the uneven height of the extremely uneven unevenness is 0.1 μm to 15 μm,
The uneven height of the micro unevenness is not less than 0.3 times and not more than 0.7 times the uneven height of the fine unevenness,
The ten-point average roughness Rz of the mold surface is 10 μm to 30 μm,
An average interval S between local peaks is 100 μm to 200 μm .

  According to this mold, the resin molded product to be obtained has fine irregularities corresponding to the fine irregularities of the mold surface formed on the surface, and the concave surface of the fine irregularities further corresponds to the fine irregularities of the mold surface. Fine micro unevenness is formed.

  In this way, since finer fine irregularities are formed on the concave and convex surfaces of the resin molded product surface, the resin molded product can be made less glossy, which is advantageous for suppressing reflection. On the other hand, since the convex portions of fine irregularities on the surface of the resin molded product are larger than the convex portions of minute irregularities, it is difficult to cause scraping or plastic deformation due to scratching. Further, even if the convex part of the micro unevenness is scraped by scraping or plastically deformed, the convex part of the micro unevenness is small, so that the scratch is not noticeable. That is, the scratch resistance is improved.

Also, uneven height of the fine irregularities Ri 1μm~30μm der uneven height of the microscopic asperities is a 0.1Myuemu～15myuemu, irregularity height of the unevenness height of the microscopic irregularities the fine asperities Since the ten-point average roughness Rz of the mold surface is 10 μm to 30 μm and the average interval S between the local peaks is 100 μm to 200 μm, scratch resistance of the resin molded product This is advantageous in reducing the gloss and suppressing the reflection without impairing the stickiness.

The manufacturing method of resin molds presented here is:
A number of fine first oxidation-resistant films are provided in the form of dots on the mold surface of the resin molding die,
By forming the first recess by etching the mold surface exposed between the first oxidation-resistant film, to form fine irregularities on the mold surface,
A second oxidation resistant film having an average diameter smaller than the average diameter of the first oxidation resistant film is provided in the form of dots on the mold surface having the fine irregularities,
By forming a second recess having a depth smaller than that of the first recess by etching of the mold surface exposed between the second oxidation-resistant films, the fine unevenness is further reduced on the convex and concave surfaces. It is characterized by forming.

  In the step of providing the first oxidation-resistant film in the form of dots, the average diameter of the first oxidation-resistant film is set to 23 μm to 250 μm, and in the process of providing the second oxidation-resistant film in the form of dots, the average of the second oxidation-resistant film It is preferable to make the diameter smaller than the average diameter of the first oxidation-resistant film in the range of 14 μm to 140 μm.

  The first oxidation-resistant film and the second oxidation-resistant film can be provided in the form of dots by spraying a liquid oxidation-resistant film material on the mold surface.

According to the mold for resin molding according to the present invention, in order to roughen the surface of the resin molded product to be molded, fine irregularities are formed on the mold surface, and finer irregularities are further formed on at least the convex surface of the fine irregularities. The unevenness height of the fine unevenness is 1 μm to 30 μm, the unevenness height of the extremely unevenness is 0.1 μm to 15 μm, and the unevenness height of the extremely unevenness is the unevenness of the fine unevenness. Since the height is 0.3 times or more and 0.7 times or less, the ten-point average roughness Rz of the mold surface is 10 μm to 30 μm, and the average interval S between the local peaks is 100 μm to 200 μm. It is possible to reduce gloss and suppress reflection without impairing the scratch resistance.

It is sectional drawing which shows typically the metal mold | die for resin molding which concerns on this invention. It is sectional drawing which shows typically each step in manufacture of the metal mold for resin molding. It is sectional drawing which shows typically the state of the resin molding by the resin mold. It is sectional drawing which shows typically the resin molded product obtained by the resin molding. It is a roughness curve figure of the mold surface of the resin mold. It is a roughness curve figure of another place of the mold surface of the mold for resin molding.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the invention, its application, or its use.

<Mold for resin molding>
The mold 1 for resin molding shown in FIG. 1 has fine irregularities formed on the mold surface, and finer irregularities are formed on the convex and concave surfaces of the irregularities. The fine unevenness and the extremely unevenness do not create a macroscopic shape of the resin molded product, but are unevenness for roughening the surface of the resin molded product.

  That is, in the mold 1, 2 is a first recess that forms the fine irregularities on the mold surface, and 3 is a convex surface of the fine irregularities and a second recess that forms the micro irregularities on the concave surface. The depth (concave / convex height) d2 of the second concave portion 3 that forms the microscopic irregularities is shallower than the depth (concave / convex height) d1 of the first concave portion 2 that forms the fine irregularities. That is, the micro unevenness is smaller than the micro unevenness.

  The depth d1 of the first recess 2 is 1 μm to 30 μm, and the depth d2 of the second recess 3 is shallower than the first recess 2 in the range of 0.1 μm to 15 μm. Further, the depth d3 of the second recess 3 is not less than 0.3 times and not more than 0.7 times the depth d1 of the first recess 2. The ten-point average roughness Rz of the mold surface having the fine unevenness and the extremely unevenness is 10 μm to 30 μm, and the average interval S between the local peaks is 100 μm to 200 μm. The fine irregularities are reflected in the ten-point average roughness Rz and the average interval S between the local peaks.

<Manufacturing method of resin mold>
A method for manufacturing the resin molding die 1 will be described with reference to FIG.

-First etching step-
After pretreatment (degreasing, pickling, polishing, etc.) of the mold surface of the mold 1, a large number of fine first oxidation-resistant films (resist) 5 are scattered on the mold surface as shown in FIG. Adhere. For this adhesion, a spray gun including a coating material container for storing a liquid oxidation resistant coating material and a gun body for ejecting the oxidation resistant coating material supplied from the coating material container by air pressure can be used. By spraying a liquid oxidation-resistant film material onto the mold surface with a spray gun, a large number of fine first oxidation-resistant films 5 are adhered to the mold surface in the form of dots. In this step, the average diameter of the first oxidation resistant films 5 is set to 23 μm to 250 μm, and the interval between the adjacent first oxidation resistant films 5 is set to, for example, 23 μm to 250 μm.

  Next, as shown in FIG. 2 (B), the mold surface exposed between the first oxidation-resistant films 5 is chemically etched to form the first recess 2. That is, the mold 1 is immersed in an etching solution containing phosphoric acid, nitric acid and the like. In this immersion, portions other than the mold surface of the mold 1 are masked. By this etching, first recesses 2 having an average depth of 1 μm to 30 μm are formed on the mold surface exposed between the first oxidation resistant films 5. Thereafter, the first oxidation-resistant film 5 and rust are removed from the mold surface (FIG. 2C).

-Second etching step-
As shown in FIG. 2 (D), a large number of second oxidation-resistant films 6 are attached in a dotted pattern on the mold surface on which fine irregularities are formed by the first recesses 2. That is, as in the case of the first oxidation resistant film 5, the liquid oxidation resistant film material is sprayed onto the mold surface with a spray gun, so that the second oxidation resistant film 6 is adhered in the form of dots. The second oxidation-resistant film 6 adheres to the convex and concave surfaces of the fine irregularities formed by the first concave portions 2 in the form of dots. In this step, the average diameter of the second oxidation resistant film 6 is smaller than the average diameter of the first oxidation resistant film 5 in the range of 14 μm to 140 μm, and the interval between the adjacent second oxidation resistant films 6 is set. It is made smaller than the said space | interval of the 1st oxidation-resistant film 5 in the range of 14 micrometers-140 micrometers.

  Next, by masking portions other than the mold surface of the mold 1 and immersing the mold 1 in an etching solution containing phosphoric acid, nitric acid, etc., the chemistry of the mold surface exposed between the second oxidation-resistant films 6 is performed. Etching is performed. As a result, as shown in FIG. 2 (E), the depth is 0.1 μm to 15 μm on the mold surface exposed between the second oxidation-resistant films 6, that is, on the convex and concave surfaces of the fine irregularities by the first concave portion 2. In this range, the second concave portion 3 shallower than the first concave portion 2 is formed. Thereafter, the second oxidation-resistant film 6 and rust are removed from the mold surface (FIG. 2 (F)).

-Adjustment of the diameter of the first oxidation resistant film and the second oxidation resistant film-
The diameter and interval of each of the first oxidation-resistant film 5 and the second oxidation-resistant film are determined by the spraying distance (distance between the nozzle and the mold surface: 30 cm to 40 cm) or the spraying pressure (air pressure; (4 atm to 6 atm) can be adjusted. For example, when the first oxidation resistant film 5 is adhered to the mold surface, the air pressure is set to a low value in the range of 4 to 6 atmospheres, and when the second oxidation resistant film 6 is adhered to the mold surface, the air pressure is decreased. What is necessary is just to set it high in the range of 4-6 atmospheres. Further, the shorter the spray distance, the narrower the interval between the oxidation resistant films.

-Adjustment of depth of first recess and second recess-
In the first etching step and the second etching step, chemical etching is performed at a speed that allows the mold surface to be removed by a depth of about 20 μm per minute, for example. By controlling the chemical etching time (immersion time), the depths of the first recess 2 and the second recess 3 can be adjusted. That is, in the second etching step, the immersion time of the mold 1 in the etchant is shorter than that in the first etching step so that the depth of the second recess 3 is shallower than the depth of the first recess 2. .

<Resin molded product obtained with resin mold>
When the resin molding is performed by the resin molding die 1 as shown in FIG. 3, the resulting resin molded product 7 has a first surface corresponding to the first recess 2 of the mold surface as shown in FIG. 1 convex portion 8 is formed, the surface has a fine uneven shape, and the second convex portion 9 corresponding to the second concave portion 3 of the mold surface is formed on the convex surface and concave surface of the fine uneven surface, The convex and concave surfaces become a finer irregular shape.

  The scratches (scratches) are generated when the uneven protrusions on the surface of the resin molded product 7 are scraped or plastically deformed, but the first protrusions 8 constituting the fine unevenness are relatively large and thus are scratched. Hard (plastic deformation is difficult). Since the second convex portion 9 constituting the micro unevenness is small, it is easy to be scraped (easily plastically deformed), but even if the second convex portion 9 is scraped or plastically deformed, the scratches are not conspicuous.

  Even if the fine irregularities on the surface of the resin molded product 7 are relatively large, since a finer irregularity is formed on the convex and concave surfaces of the fine irregularities, a high matting effect can be obtained. Further, the contrast between the convex and concave surfaces of the fine irregularities is also lowered by the fine irregularities formed on each of them, so that the image of the resin molded product 7 is hardly reflected on the glass surface.

<Example>
-First etching step-
The surface (mold surface) of a mold made of S50C (carbon steel for mechanical structure) was polished, and an oxidation resistant film material was sprayed onto the mold surface with a spray gun to adhere the first oxidation resistant film in the form of dots. The nozzle diameter of the spray gun used was 1.3 mm, and the spraying conditions were set so that the diameter of the first oxidation resistant film was about 70 to 80 μm. Next, the 1st recessed part 2 was formed by immersing a metal mold | die in etching liquid. The temperature of the etching solution was 23 ° C., and the etching solution was prepared so that the depth could be removed by about 20 μm in 1 minute. The immersion time of the mold was 30 seconds (target depth 10 μm of the first recess 2). Thereafter, the oxidation-resistant film and rust remaining on the mold surface were removed.

-Second etching step-
An oxidation resistant film material was sprayed onto the mold surface on which fine irregularities were formed by the first etching process using the same spray gun as in the first etching process, and the second oxidation resistant film was adhered in the form of dots. The spraying conditions were set so that the second oxidation resistant film had a diameter of about 20 to 40 μm. Next, the 2nd recessed part was formed by immersing a metal mold | die in etching liquid. The etching solution was prepared in the same manner as in the first etching step, but the immersion time of the mold was 15 seconds (target depth of the second recess is 5 μm). Thereafter, the oxidation-resistant film and rust remaining on the mold surface were removed.

  5 and 6 show roughness curves at two locations on the mold surface according to the above embodiment. The surface roughness meter used was a surface roughness measuring device S-3000 manufactured by Mitutoyo Corporation, and the stylus used had a tip radius of 2 μm and a tip angle of 60 °. The ten-point average roughness Rz of the mold surface in FIG. 5 is 15.819 μm, the average distance S between the local peaks is 143 μm, and the arithmetic average roughness Ra is 2.90 μm. The ten-point average roughness Rz of the mold surface in FIG. 6 is 16.840 μm, the average distance S between the local peaks is 140 μm, and the arithmetic average roughness Ra is 3.04 μm.

  When the scratch test was performed by scratching the surface of the resin molded product molded by the mold according to the above example with a load of 150 g with a metal needle having a tip curvature radius (R) of 0.5 mm, the scars could be visually recognized. No whitening of the wound was observed. Further, the surface of the resin molded product was in a matte state, and no conspicuous reflection of the image on the glass surface was observed.

  Here, the larger the value of the ten-point average roughness Rz (in short, the unevenness height) and the larger the value of the average distance S between the local peaks, the more advantageous the improvement in scratch resistance. This is disadvantageous in terms of glazing and reflection suppression. However, in the case of the present invention, since the fine unevenness due to the second recessed portion is formed on the convex and concave surfaces of the fine unevenness due to the first recessed portion, this extremely unevenness acts advantageously on low gloss and reflection suppression.

  The ten-point average roughness Rz of the mold surface is preferably 10 μm to 30 μm, the average interval S between the local peaks is 100 μm to 200 μm, and the arithmetic average roughness Ra is preferably 1.5 μm to 6.0 μm.

DESCRIPTION OF SYMBOLS 1 Mold 2 1st recessed part 3 2nd recessed part 5 1st oxidation-resistant film 6 2nd oxidation-resistant film 7 Resin molded product 8 1st convex part 9 2nd convex part

Claims (1)

Fine irregularities for roughening the surface of the resin molded product to be molded are formed on the mold surface, and further finer for roughening the surface of the resin molded product to be molded on at least the convex surface of the fine irregularities. Ultra-fine irregularities are formed,
The uneven height of the fine unevenness is 1 μm to 30 μm, and the uneven height of the extremely uneven unevenness is 0.1 μm to 15 μm,
The uneven height of the micro unevenness is not less than 0.3 times and not more than 0.7 times the uneven height of the fine unevenness,
The ten-point average roughness Rz of the mold surface is 10 μm to 30 μm,
A resin molding die having an average interval S between local peaks of 100 μm to 200 μm .

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