JP2005088442A - Method for manufacturing in-mold foam molded body of thermoplastic resin and molded body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an in-mold foam molded body of a thermoplastic resin which easily makes a mud-crack pattern resulting from a fusion mark of preexpanded particles sufficiently inconspicuous in almost the same molding method as conventionally performed without in-mold foam molding under excess molding conditions and shows an excellent surface profile. <P>SOLUTION: In the method for in-mold foam molding the thermoplastic resin using a molding tool having an almost regular unevenness pattern formed at least in one part of the surface of the molding tool, the recessed part width (a) and recessed part depth (c) of the unevenness pattern on the surface of the mold and the particle diameter D of the preexpanded particle, meet 0.1≤a/D≤1.0 and besides, 0.1≤c/D≤1.0. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing an in-mold foam molded body of thermoplastic resin pre-foamed particles and a molded body obtained by the method. More specifically, the present invention relates to a method for producing a foamed molded article having a good appearance such that the surface of the tortoiseshell pattern due to fusion marks between the pre-foamed particles is not conspicuous or the surface smoothness is good, and a molded article obtained by the method. .

  Conventionally, an in-mold foam molded body of thermoplastic resin pre-foamed particles is prepared by filling pre-foamed particles as raw materials into a mold consisting of a pair of males and females, blowing steam, softening the pre-foamed particles and performing secondary foaming. The pre-expanded particles are formed by heat-sealing, and then cooled and released from the mold. However, the in-mold foam molded article molded by such a method has a problem that the appearance of the molded article is not good. One reason for this is the formation of a turtle shell pattern resulting from the fusing marks between the pre-expanded particles.

  As a method of solving this problem, a method of making the turtle shell pattern inconspicuous by attaching a metal net, punching metal, or porous sheet to the mold surface, and transferring these uneven patterns to the molded body surface during molding. (Patent Literature 1, Patent Literature 2, Patent Literature 3) are disclosed.

  In Patent Document 1, a pre-foamed particle shape pattern is not formed on the surface by molding pre-foamed particles having an average particle diameter of about 5.0 mm with a mold having a metal mesh of about 50 to 100 mesh mounted on the inner wall. Although there is a description that it can be obtained, the surface appearance does not become sufficiently good only under these conditions, so the pre-expanded particles at the time of molding more than necessary as compared with the normal molding method while using the mold It is necessary to promote the expansion (secondary foaming) of the particles, increase the adhesion between the pre-foamed particles, and reduce the gaps between the pre-foamed particles as much as possible, that is, to prevent the formation of a turtle shell pattern on the surface of the molded product. The For this reason, the water vapor pressure at the time of molding heating and the molding condition factors represented by the heating time are set excessively compared to normal molding, the pre-expanded particles are given an internal pressure higher than usual, or the pre-expanded particles are excessive. It was necessary to set the molding conditions to give excessive foaming force to the pre-foamed particles by filling the mold in a compressed state. In particular, it is difficult to secure a sufficient surface property in a complex-shaped molded body, and the stability tends to be lacking. In order to avoid this, it is necessary to set the molding conditions excessively. However, if this happens, there is a disadvantage that the cooling time is inevitably prolonged, and it is unavoidable that the molding cycle becomes long, and productivity is increased. There was a problem of making it worse.

  Patent Document 2 describes that a wire mesh of 100 to 300 mesh is simply used, but the problem is not solved in terms of the particle diameter of the pre-expanded particles to be used. There is a problem that becomes longer and the productivity becomes worse. Patent Document 3 also has a problem that the molding cycle becomes long because there is no description of the problem solving from the particle size of the pre-expanded particles used in particular and there is a description that molding is performed under special molding conditions. .

  As a method for solving these problems, Patent Document 4 discloses that a geometrical surface composed of concave and convex stripes having a pitch equal to or narrower (1/4 or more) than the unit diameter of the surface crystalline pattern of the material is formed on the surface of the molded body. It describes how to make the turtle shell pattern inconspicuous by applying a study pattern. However, although the pitch of the concavo-convex pattern is limited here, the depth of the concavo-convex pattern is not mentioned. Therefore, a sufficient improvement effect cannot be obtained.

In addition, as a technique for improving the surface smoothness, Patent Document 5 discloses a molded article having a concavo-convex pattern that has a specific surface roughness, and by reducing the height difference of the concavo-convex pattern, There is a description that the surface shape is not perceived as peculiar. However, with this method, it is possible to make local voids and protrusions inconspicuous by reducing the height difference of the uneven pattern, but this alone has the problem that the above-described turtle shell pattern cannot be sufficiently resolved. It was.
Japanese Patent Laid-Open No. 60-8047 Japanese Utility Model Publication No. 57-149258 Japanese Unexamined Patent Publication No. 6-198754 Japanese Utility Model Publication No. 63-108728 Japanese Patent Laid-Open No. 4-25439

  Therefore, in view of the above problems, the present inventors have made the turtle shell pattern caused by the fusion marks of the pre-foamed particles sufficiently inconspicuous, and the thermoplastic resin in-mold foam molded article having good surface smoothness. As a result of earnestly examining the manufacturing method, when the dimensions such as the particle diameter of the pre-expanded particles to be used and the width or depth of the uneven pattern on the surface are in a specific relationship, without making the turtle shell pattern inconspicuous under excessive molding conditions, The inventors have found that an in-mold foam molded article having a desired appearance can be obtained under molding conditions almost the same as conventional ones, and have completed the present invention.

  That is, the first aspect of the present invention is a method for foam molding in a thermoplastic resin mold using a molding die having a substantially regular concavo-convex pattern on at least a part of the surface of the molding die, and the concave width a of the concavo-convex pattern on the mold surface. And the depth c of the recess and the particle diameter D of the pre-expanded particles satisfy 0.1 ≦ a / D ≦ 1.0 and 0.1 ≦ c / D ≦ 1.0. The present invention relates to an in-mold foam molding method.

As a preferred embodiment,
(1) In the uneven pattern on the mold surface, the recess width a, the protrusion width b, and the recess depth c are
(B + c) /a≧0.5 and a molding die satisfying c ≧ b is used,
(2) A thermoplastic resin pre-expanded particle having a particle diameter D of 0.1 mm or more and 2.0 mm or less is used, and a molding die having a concave-convex depth c of 0.4 mm or less is used.
(3) The thermoplastic resin is a polypropylene resin or a polyethylene resin.
(4) Using a molding die in which the uneven pattern is formed on the surface of the molding die,
(5) A mold consisting of a mold A having the concavo-convex pattern on the surface of the molding die and having no steam holes, and a mold B having no concavo-convex pattern on the surface of the molding mold and having steam holes. Using the mold,
(6) A mold A having the uneven pattern on the surface of the molding die and having no steam holes and a mold B not having the uneven pattern on the surface of the molding mold and having the steam holes are clamped. After forming the mold, the thermoplastic resin particles are filled into the mold, water vapor is supplied from the vapor holes of the mold B, and the preliminary foaming is performed at a temperature lower than the temperature at which the foamed particles are fused to each other. Pre-heating the particles, steaming the pre-expanded particles with water vapor, and then removing the drain, followed by main heating the pre-expanded particles at a temperature equal to or higher than the temperature at which the pre-expanded particles fuse together,
The present invention relates to the above-mentioned thermoplastic resin in-mold foam molding method.

  2nd of this invention is related with the thermoplastic resin in-mold expansion-molding body manufactured by the manufacturing method of the said description.

  According to the present invention, by adopting a predetermined particle diameter of the pre-expanded particles and the size of the concavo-convex pattern on the mold surface, compared with the conventional method, the tortoise shell which was a disadvantage in the in-mold expansion molding of the pre-expanded particles The pattern can be eliminated easily and stably, and the surface smoothness can be improved. In addition, since the molded body obtained in this way has an excellent appearance, it can be suitably used for a portion that emphasizes the appearance of building materials, packaging materials, automobile members, and the like.

  One example of a method for producing a thermoplastic resin in-mold foam molded product of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic explanatory view showing an embodiment of a mold used in the production method of the present invention. In FIG. 1, a mold A side frame 5 to which a mold A1 is fixed is connected to, for example, a cylinder (not shown) of a molding machine, and the mold A1 is moved together with the mold A side frame 5 to move the mold A1. Clamping and mold opening can be performed, and a molding space 7 is formed between the mold A1 and the mold B2 in the mold-clamped state. A plurality of vapor holes 8 are provided in each of the mold A1 and the mold B2.

  An uneven pattern is provided on the mold surface corresponding to the surface that requires excellent surface properties of the obtained molded body. In the present invention, since at least a part of the surface has a substantially regular concavo-convex pattern, the entire mold surface may be provided with a concavo-convex pattern according to the desired appearance of the in-mold foam molded article. It may be applied to the part. A plurality of uneven patterns having different patterns may be used. For example, in the case where a surface property is required on one surface of a plate-like molded body, an uneven pattern may be formed on the surface of the mold A1 as shown in FIG.

  There is no particular limitation on the shape of the concave and convex portions of the concavo-convex pattern, and at least one of the concave or convex portions has an independent shape such as a polygon such as a triangle, a quadrangle, or a hexagon, or a circle such as a circle or an ellipse. Can be illustrated. The mold surface pattern concave portion width a, the mold surface pattern convex portion width b, and the mold surface pattern concave portion depth c referred to in the present invention are the centers of independent shapes of the concave portion and the concave portion or the convex portion and the convex portion that are closest to each other. The concave part width a, the convex part width b, and the concave part depth c in the cross section on the line which passes mutually are said. Examples of the line passing through the centers of the most adjacent independent shapes can be illustrated as AA lines in FIGS. Examples of the cross-sectional shape are as shown in FIGS. 5, 6, 7, and 8. FIG. 5 shows a simple concavo-convex pattern, and FIG. 6 shows a concavo-convex pattern with rounded corners. FIG. 7 shows a concavo-convex pattern having a V-shaped concave shape, and FIG. 8 shows a cross-sectional concavo-convex pattern when a metal net is installed on the mold surface. The mold surface recess width a, the mold surface protrusion width b, and the mold surface pattern recess depth c are respectively defined as shown in the figure. When the concavo-convex pattern is configured with a curve as shown in FIG. 6, the concave portion width a and the convex portion width b are defined based on the inflection point. In the case as shown in FIG. 7, the concave portion width a and the convex portion width b are defined based on the midpoint of one side constituting the concavo-convex pattern. When a concavo-convex pattern is imparted using a wire mesh or the like as shown in FIG. 8, the thickness of the wire constituting the wire mesh is the protrusion width b, and the dimension between the wire and the wire (opening dimension) is the recess width a. The thickness of the wire mesh corresponds to the recess depth c.

  The substantially regular concavo-convex pattern of the present invention means that when the concave portion has the independent shape, the distance between the concave portion and the concave portion (mold surface pattern convex portion width b) is substantially constant. When it has an independent shape, it means that the distance between the convex part and the convex part (mold surface pattern concave part width a) is substantially constant.

  As a method for forming a concavo-convex pattern on the surface of the mold, any method can be used as long as the desired concavo-convex pattern can be transferred to the surface of the resulting molded body. And a method of using a die that has been processed such as excavating the die itself. The mold used in the former method may be a mold in which a porous material such as a metal mesh or punching metal is attached to the mold surface as shown in FIG. 2, or a mold used in the latter method. As shown in FIG. 3, a concavo-convex pattern may be provided on the surface of the mold itself. In the latter case, the steam hole is provided in a convex part (a concave part in the molded body) of the mold as shown in FIG. 3, so that the effect of making it difficult to recognize the steam hole trace on the surface of the molded product is obtained. .

  In the present invention, the concavo-convex pattern on the mold surface is 0.1 ≦ a / D between the mold surface pattern recess width a and the mold surface pattern recess depth c used. It is necessary to satisfy the relationship of ≦ 1.0 and 0.1 ≦ c / D ≦ 1.0. By providing such a pattern, the reason why it is difficult to observe the turtle shell pattern on the surface of the molded body is not clear, but the surface of the molded body is irregularly reflected by the uneven pattern, and the effect of making the turtle shell pattern inconspicuous, or particles It is thought that there is an effect that the joint portion is pushed into the convex portion of the mold, and a slight gap between the particle pattern and the particle is hidden in the concave portion by the molded product and becomes inconspicuous. By using a mold having a concavo-convex pattern on the surface of the present invention, it is considered that an in-mold foam molded article having good surface properties can be obtained without molding under excessive molding conditions during molding.

  When c / D is less than 0.1, a turtle shell pattern is easily observed on the surface of the molded body. In addition, the larger the c / D, the more difficult it is to observe the turtle shell pattern. However, if the value exceeds a certain value, a substantial effect cannot be expected. Conversely, the pre-expanded particles are expanded by expansion during in-mold foam molding. Since it is difficult to reach the bottom surface of the mold recess and the mold transferability tends to deteriorate and the surface tends to deteriorate, it is appropriate to set the upper limit to 1.0, preferably 0.2 ≦ c. By setting /D≦1.0, the effects of the present invention can be more easily exhibited.

  When a / D exceeds 1.0, the intergranularity is easily arranged on the outermost surface of the molded product, and the turtle shell pattern is easily confirmed. When it is less than 0.1, it becomes difficult for the pre-expanded particles to enter the concave portion of the mold during heating, and it becomes difficult to accurately transfer the concave / convex pattern of the mold. Preferably, by making 0.2 ≦ a / D ≦ 0.8, the effect of the present invention can be further exhibited.

In the present invention, the mold surface pattern recess width a, the mold surface pattern protrusion width b, and the mold surface pattern recess depth c are (b + c) /a≧0.5, c ≧ b.
By using a mold that satisfies the above, the turtle shell pattern on the surface of the molded body can be made inconspicuous more easily. The detailed reason why such an effect is obtained is not clear, but if (b + c) / a is large, the ratio of the depression (shade) in the molded body increases, and the effect of hiding the turtle shell pattern in the recessed part of the molded product more The value is preferably 0.5 or more, and more preferably 0.7 or more.

  In addition, when c is smaller than b, the effect of shadowing the bottom surface of the recess in the molded product is weakened, and the turtle shell pattern is easily observed. Therefore, c ≧ b is preferable. The other relationship between c and b is not particularly limited, but the upper limit of c is more preferably set to 10 times or less of b because the strength of the part of the mold is insufficient.

  The mold A1 and the mold B2 are clamped, and the thermoplastic pre-expanded particles are filled into the molding chamber 7 of the mold through a feeder 9.

  The thermoplastic resin used for the thermoplastic resin pre-expanded particles includes polystyrene, polypropylene, polyethylene, ethylene-propylene copolymer, propylene-vinyl chloride copolymer, propylene-butene copolymer, propylene-maleic anhydride copolymer, ethylene-propylene-butene. A terpolymer etc. are mention | raise | lifted and these can be used individually or in mixture of 2 or more types. Among these thermoplastic resins, usually, a gap between particles is likely to occur on the surface of the molded body, and the effects of the present invention are easily exhibited. It is suitable for a resin.

  As a method for producing the thermoplastic resin pre-foamed particles, a known method may be used. For example, in a pressure vessel, the thermoplastic resin particles contain a volatile foaming agent, dispersed in water with stirring, and under pressure. Examples thereof include a method of releasing the aqueous dispersion to a low pressure region after heating to a predetermined foaming temperature, but the present invention is not limited to such a method.

  The particle diameter D of the pre-expanded particles used in the present invention is not particularly limited, and may be about 0.5 to 4.0 mm ordinarily used, or a smaller particle diameter. However, if the particle size is too small, the space between the particles that become the passage of the vapor becomes small and it becomes difficult to efficiently heat the pre-expanded particles, so the lower limit may be 0.1 mm. preferable.

  Furthermore, as a preferable aspect in the present invention, a thermoplastic resin pre-expanded particle having a particle diameter D of 0.1 mm or more and 2.0 mm or less is used with a mold having a surface unevenness pattern recess depth c of 0.4 mm or less. . By using such a condition, a molded article having a smooth surface with no ruggedness and having a fine concavo-convex pattern, that is, having a smooth surface, that is, having a good surface smoothness can be obtained relatively easily. is there. The reason why the particle diameter D is preferably 2.0 mm or less is as follows.

  In order to give a smooth impression with less ruggedness on the surface of the molded body, it is preferable that c is 0.4 mm or less. On the other hand, the larger the c / D, the greater the effect that the turtle shell pattern on the surface becomes difficult to be observed. Therefore, the smaller the particle diameter D, the smaller the value is preferably 2.0 mm or less.

  The particle diameter D of the pre-expanded particles in the present invention is defined by the following method.

  For example, pre-expanded particles (total weight W of particles) of about 500 ml cup are prepared, and a screening test is performed using a standard sieve having an opening defined by JIS Z 8801.

As a result, it is calculated by the following formula from the opening size M _i of each sieve and the weight W _i of the pre-expanded particles remaining on each sieve.

D = (W ₁ × M ₁ + W ₂ × M ₂ +... W _i × M _i ) / W
When filling the thermoplastic resin pre-expanded particles into the molding chamber 7 through the feeder 9, the pre-expanded particles are previously pressurized using a pressurized gas, and the pressurized gas is sufficiently permeated into the pre-expanded particles. In addition, the molding chamber 7 may be filled with an internal pressure applied, or the pre-expanded particles may be filled into the molding chamber 7 in a compressed state using a pressurized gas. The inside of the molding chamber 7 may be filled as it is without applying an internal pressure or compressing it. The present invention is not limited by such a filling method, but from the viewpoint that it is possible to expect the effect of more expanding the pre-expanded particles and filling the gaps between the particles, the pre-expanded particles are preliminarily applied with internal pressure or It is preferable to fill the pre-expanded particles in a compressed state.

  After filling the thermoplastic resin pre-expanded particles into the molding chamber 7, water vapor is introduced into the molding chamber 7. Water vapor is introduced from the mold A side steam line 11 and the mold B side steam line 10 into the steam chambers 3 and 4 on the back of the molds A1 and B2, respectively. The steam introduced into the steam chambers 3 and 4 is further introduced into the molding chamber 7 through the steam holes 8 of the molds A1 and B2.

  First, water vapor is supplied into the molding chamber 7 from the respective vapor holes 8 of the molds A1 and B2 so that the temperature becomes lower than the temperature at which the pre-expanded particles are fused, and the pre-expanded particles are preliminarily heated. (One side heating, reverse one side heating).

  Next, the pre-expanded particles are subjected to main heating at a temperature equal to or higher than a temperature at which the pre-expanded particles are fused to each other, preferably at a temperature higher by 5 ° C. than the fusing temperature. The pressure of the water vapor at this time is not different from the conventional in-mold foam molding, for example, not less than the temperature at which the pre-foamed particles are fused to each other and 30 ° C. or higher than the temperature at which the pre-foamed particles are fused. Things are preferable.

  The fusing temperature refers to pre-expanded particles when pre-expanded particles are filled in a mold having a depth of about 50 mm and water vapor at a predetermined temperature (predetermined pressure) is introduced into the mold for 10 to 20 seconds. It refers to the minimum temperature at which the parts can be fused together to maintain the shape of the foamed molded product.

  After the pre-expanded particles are heated, the molded body is cooled, and the mold A1 and the mold B2 are opened to obtain an in-mold foam molded body. The temperature at the time of cooling varies depending on the type of pre-expanded particles and the expansion ratio of the foamed molded product, so it cannot be determined unconditionally. No temperature is chosen.

  The foaming ratio of the foam can be applied within the range normally used, but if it is too large, the shrinkage of the resulting molded product tends to increase, so it is 3 to 60 times, especially It is preferably about 3 to 50 times.

  Furthermore, in the mold having a concavo-convex pattern on the surface according to the present invention, it is possible to obtain a molded article having a good surface property without a vapor hole trace by not providing a vapor hole in a portion having a concavo-convex pattern as shown in FIG. It is.

  In this case, since there is no vapor hole in the portion having the concavo-convex pattern, heating of the portion having the concavo-convex pattern tends to be insufficient, and the turtle shell pattern tends to be observed on the surface of the molded body. By molding by this method, the effect of improving surface properties can be expected more easily.

  Specifically, after forming the mold by clamping the mold A1 having the concavo-convex pattern and not having the vapor holes and the mold B2 having no concavo-convex pattern and having the vapor holes, Filling the mold with plastic resin particles, supplying water vapor from the vapor holes of the mold B2, preheating the pre-expanded particles at a temperature lower than the temperature at which the expanded particles are fused together, and pre-expanding It can be obtained by steaming the particles with water vapor and then heating the pre-expanded particles at a temperature equal to or higher than the temperature at which the pre-expanded particles are fused together after removing the drain.

  Steaming with water vapor as described above means that after the preheating is performed, the preheating state is maintained, or the supply state of water vapor is stopped, for example, by effectively using the latent heat of the water vapor. This refers to creating a state where the expanded particles can be heated uniformly. When the pre-expanded particles are steamed in this way, the time required for such steaming varies depending on the thickness of the pre-expanded particle layer in the mold, the size of the pre-expanded particles, the shape, the expansion ratio, etc. However, it is generally desirable that the thickness of the pre-expanded particle layer is about 50 mm, for example, about 3 seconds or longer, preferably 5 seconds or longer, more preferably 10 seconds or longer.

  After the steaming, there is a drain (moisture) between the pre-foamed particles, and if the main heating is performed in this state, the poor fusion between the pre-foamed particles occurs, so the drain produced by the steam is removed. It is preferable. The method for removing the drain is not particularly limited. For example, the drain is removed by a method of vacuuming the interior of the molding chamber 7 using the vapor hole 8 provided in the mold B2.

  The steam during the main heating may be supplied from the steam line 10 through the steam chamber 4 to the molding chamber 7 through the steam hole 8 of the mold B2, and at the same time from the steam line 11 to the steam chamber 3. Although it may be introduced, the latter is preferable because the mold A1 can be heated more efficiently by heating.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further in detail, these do not limit this invention at all.
(Example 1)
A mold (molding chamber dimensions: 400 mm length, 300 mm width, 20 mm depth) using a stainless steel plain woven wire mesh (40 mesh) having a concavo-convex pattern shown in Table 1 as a porous material was prepared.

  Polypropylene-based pre-foaming using an ethylene-propylene random copolymer (ethylene content: 2.8 mol%, melt flow rate: 7 g / 10 min, melting point: 145 ° C.) as a base resin as thermoplastic resin pre-foaming particles Particles (foaming ratio: 3.4 times, particle diameter: 1.76 mm) are put in a pressure-resistant container in advance and given an internal pressure of 0.05 MPa by air pressure, and this is filled into the mold through the feeder 9 did.

  Next, water vapor is sequentially introduced into the molding chamber 7 from the vapor holes of the mold A1 and the mold B2, respectively, and after one heating and reverse one heating are performed, water vapor (vapor pressure 0.35 MPa, temperature 146 to 150 is used as the main heating. ℃) is introduced into the molding chamber 7 for 10 seconds, the pre-expanded particles are expanded and fused together, then cooled at 30 ° C for 120 seconds, and then the mold A1 and the mold B2 are opened. Thus, a molded body in which the pattern based on the porous material surface was transferred to the surface in contact with the porous material was obtained.

The appearance of the obtained molded body was evaluated according to the following evaluation criteria. The results are shown in Table 1.
-Evaluation criteria for molded product appearance-
(1) Tortoise shell pattern:
○… The turtle shell pattern is not noticeable △… A little turtle shell pattern is observed if you look closely, but the level that does not pose a problem × ・ ・ ・ The turtle shell pattern can be easily identified, and voids are also observed (2 ) Surface smoothness:
○ ・ ・ ・ Smooth and smooth surface Δ ・ ・ ・ Surface with a rough surface (Example 2)
A molded body in the same manner as in Example 1 except that a stainless wire mesh (20 mesh) having an uneven pattern shown in Table 1 is used, and polypropylene pre-expanded particles having an expansion ratio of 3.6 times and a particle diameter of 2.43 mm are used. Got.
(Example 3)
Polypropylene pre-expanded particles with an expansion ratio of 15.6 times, a particle diameter of 3.25 mm and an internal pressure of 0.10 MPa were filled into a mold using a stainless steel wire mesh (18 mesh) having the uneven pattern shown in Table 1. A molded body was obtained in the same manner as in Example 1 except that steam (vapor pressure 0.30 MPa, temperature 142 to 146 ° C.) was introduced into the molding chamber 7 for 8 seconds as the main heating.
Example 4
A molded body was obtained in the same manner as in Example 1 except that a mold having a concavo-convex pattern shown in Table 1 (dimensions of molding chamber: length 400 mm, width 300 mm, depth 20 mm) was used on the surface of the mold itself. .
(Example 5)
A molded body was obtained in the same manner as in Example 4 except that the mold having the uneven pattern shown in Table 1 was used.
(Example 6)
Molding formed by clamping a mold A having the concavo-convex pattern shown in Table 1 on its surface and not having a vapor hole and a mold B having no concavo-convex pattern and having a vapor hole A mold (dimensions of molding chamber: length 400 mm, width 300 mm, depth 20 mm) was prepared.

  Polypropylene-based pre-foaming using an ethylene-propylene random copolymer (ethylene content: 2.8 mol%, melt flow rate: 7 g / 10 min, melting point: 145 ° C.) as a base resin as thermoplastic resin pre-foaming particles Particles (foaming ratio: 3.4 times, particle diameter: 1.76 mm) are put in a pressure-resistant container in advance and given an internal pressure of 0.05 MPa by air pressure, and this is filled into the mold through the feeder 9 did.

  Next, water vapor (vapor pressure 0.12 MPa, temperature 120 to 124 ° C.) is introduced into the molding chamber from the vapor hole of the mold B, preheated, and the pre-foamed particles are steamed for 10 seconds. The drain and water vapor were sucked and removed using a vacuum pump so that the pressure was a gauge pressure of −0.03 MPa or less.

Thereafter, water vapor (vapor pressure: 0.35 MPa, temperature: 146 to 150 ° C.) is introduced from the vapor hole of the mold B for 15 seconds, and the pre-expanded particles are expanded and fused together, and then using water at 30 ° C. for 120 seconds. After cooling, the molds A and B were opened to obtain a molded body in which a pattern based on the uneven pattern on the mold surface was transferred to the surface in contact with the mold A.
(Comparative Example 1)
A molded body was obtained in the same manner as in Example 1 except that a stainless steel wire mesh (150 mesh) having an uneven pattern shown in Table 1 was used.
(Comparative Example 2)
Polypropylene pre-expanded particles having an expansion ratio of 21.1 times, a particle diameter of 3.41 mm and an internal pressure of 0.12 MPa were filled into a mold using a stainless steel wire mesh (50 mesh) having the uneven pattern shown in Table 1. A molded body was obtained in the same manner as in Example 1 except that steam (vapor pressure 0.28 MPa, temperature 140 to 144 ° C.) was introduced into the molding chamber 8 for 8 seconds as the main heating.
(Comparative Example 3)
A molded body was obtained in the same manner as in Example 4 except that a mold having the uneven pattern shown in Table 1 on the surface of the mold itself was used.

It is a schematic explanatory drawing which shows one embodiment of the shaping | molding die used for the manufacturing method of this invention. It is typical sectional drawing which shows one Example of the metal mold | die which concerns on this invention. It is typical sectional drawing which shows one Example of the metal mold | die which concerns on this invention. It is typical sectional drawing which shows one Example of the metal mold | die which concerns on this invention. It is a detailed enlarged view which shows one Example of the uneven | corrugated pattern formation part cross section of the metal mold | die which concerns on this invention. It is a detailed enlarged view which shows one Example of the uneven | corrugated pattern formation part cross section of the metal mold | die which concerns on this invention. It is a detailed enlarged view which shows one Example of the uneven | corrugated pattern formation part cross section of the metal mold | die which concerns on this invention. It is a detailed enlarged view which shows one Example of the uneven | corrugated pattern formation part cross section of the metal mold | die which concerns on this invention. It is a detailed enlarged view which shows one Example of the uneven | corrugated pattern formation part of the metal mold | die which concerns on this invention. It is a detailed enlarged view which shows one Example of the uneven | corrugated pattern formation part of the metal mold | die which concerns on this invention.

Explanation of symbols

1 Mold A
2 Mold B
3, 4 Steam chamber 5, 6 Frame 7 Molding chamber 8 Steam hole 9 Feeder 10, 11 Steam line 12, 13 Drain line 14 Porous material

Claims (8)

In a thermoplastic resin in-mold foam molding method using a molding die having a substantially regular concavo-convex pattern on at least a part of the surface of the molding dies, a concave width a and a concave depth c of the mold surface concavo-convex pattern and preliminary foaming The particle diameter D of the particles is
0.1 ≦ a / D ≦ 1.0,
And,
A thermoplastic resin in-mold foam molding method characterized by satisfying 0.1 ≦ c / D ≦ 1.0. In the concavo-convex pattern on the mold surface, the concave portion width a, the convex portion width b, and the concave portion depth c are (b + c) /a≧0.5,
And,
c ≧ b
The thermoplastic resin in-mold foam molding method according to claim 1, wherein a molding die satisfying the requirements is used.   2. The molding die having a concave-convex depth c of 0.4 mm or less of the surface unevenness pattern of the thermoplastic resin pre-expanded particles having a particle diameter D of 0.1 mm to 2.0 mm, 3. The method for foam molding in a thermoplastic resin mold according to 2.   The thermoplastic resin in-mold foam molding method according to any one of claims 1 to 3, wherein the thermoplastic resin is a polypropylene resin or a polyethylene resin.   The thermoplastic resin in-mold foam molding method according to any one of claims 1 to 4, wherein a molding die in which the uneven pattern is formed on a surface of a molding die is used.   A mold comprising a mold A having the uneven pattern on the surface of the molding die and having no steam holes and a mold B having the uneven pattern on the surface of the mold and having the steam holes is used. The thermoplastic resin in-mold foam molding method according to any one of claims 1 to 5.   A mold A is formed by clamping a mold A having the concavo-convex pattern on the surface of the molding die and having no steam holes and a mold B having the concavo-convex pattern on the surface of the molding mold and having the steam holes. After that, the thermoplastic resin particles are filled in the mold, water vapor is supplied from the vapor holes of the mold B, and the pre-expanded particles are preliminarily prepared at a temperature lower than the temperature at which the expanded particles are fused to each other. The pre-foamed particles are heated at a temperature equal to or higher than a temperature at which the pre-foamed particles are fused to each other after heating, steaming the pre-foamed particles with water vapor, and then removing the drain. The thermoplastic resin in-mold foam molding method according to any one of the above.   A thermoplastic resin in-mold foam molded product produced by the production method according to claim 1.

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