JPH11348080A - Injection mold for plastic product and manufacture of the mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable molding of a product of high quality having a high gloss and being free of warpage and the like and to provide a manufacturing method enabling simple formation of heating-medium circulating passages in a mold. SOLUTION: First heating-medium circulating passage forming threads 5 are formed of a hollow forming material being meltable later on the rear side of a thin plate 2 for forming a molding surface made to conform to the shape of the surface of a product, and also a second covering layer 8 is formed on the surfaces of the first heating-medium circulating passage forming threads 5. Second heating-medium circulating passage forming threads 6 are formed thereafter by filling the same hollow forming material as the above in recessed thread grooves which are formed on the surface of the second covering layer 8 and in spaces between the heating-medium circulating passage forming threads 5, and further the second covering layer 8 is formed on the surfaces of these second heating-medium circulating passage forming threads 6. Then, the hollow forming material having formed the first and second heating-medium circulating passage forming threads 5 and 6 is melted off by heating. Thereby first heating- medium circulating passages 9 and second heating-medium circulating passages 10 are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of molding a plastic product having a high quality surface by heating and cooling the surface temperature of a mold in a short period of time, with high accuracy, using plastic as a material. The invention relates to a mold that can be made and a method of making this mold.

[0002]

2. Description of the Related Art In a conventional plastic molding method in which a mold is used at room temperature, a material resin such as a molten thermoplastic resin rapidly cools, solidifies, and shrinks in the mold.
In addition to appearance defects such as welds, flow marks, sink marks, etc., on the product surface, fillers such as small shrinkage glass and rubber particles such as butadiene that are contained in the resin to reinforce the mechanical strength of the resin It is selectively left on the surface and forms fine irregularities or portions having different optical characteristics on the resin surface, thereby impairing the appearance of the high gloss product surface. Such poor appearance and poor gloss reduce the value of the product by impairing the appearance of the product.
There is also a problem that the cost for repair is high.

[0003] The above-mentioned poor appearance and poor gloss are caused by adjusting the flow of the resin at the time of filling the resin, reducing the amount of fillers and rubber particles contained in the material resin, and reducing the particle size. Although the improvement can be made to some extent by improving the material resin itself, the most effective way to prevent the appearance failure from occurring is to heat the portion of the mold on the visible surface side where the material resin flows to a high temperature. .

[0004] Based on such a concept, there has been proposed a method of heating the mold surface on the visible side of the product by, for example, an electric heater. However, this method takes a long time for heating or generates uneven heating. As a result, the molding cycle is prolonged and the product cost is increased, and there is a quality problem. Therefore, there is a proposal for improving the temperature responsiveness of the mold so as to shorten the time required for heating the mold.

[0005] A mold in which an induction coil is provided on the outer periphery of the mold (Japanese Utility Model Laid-Open No. 62-111182). A high-frequency induction coil made of a copper pipe is provided in a mold so that cooling water flows in the pipe (Japanese Patent Laid-Open No. 63-1).
No. 5707). One in which a movable insert provided with an electric heater can be taken in and out of a mold (JP-A-63-15719). A device for rapidly heating and cooling the mold temperature adjusting medium or a device for switching the heated and cooled medium to the mold and supplying it to the mold outside the mold, and the supplied heating and cooling medium for the temperature adjusting medium in the mold. A mold that can be heated and cooled by passing through a circulation path (JP-A-62-15707, JP-A-62-15707,
JP-A-2-208918, JP-B-7-25115).

The present inventors formed a heat medium circulating flow path forming strip on a back surface of a thin plate according to the surface shape of a product using a cavity forming material that can be melted later, and then formed the heat medium circulating flow path forming strip. Forming a metal coating layer on the surface of, and then elute the cavity forming material from the inside of the coating layer to produce a temperature control molding surface member having a heat medium circulation channel formed between the thin plate and the coating layer. Incorporate it into the backing to make an insert, incorporate this insert into the molding surface of the mold, and forcibly circulate the heating or cooling heat medium in the heat medium circulation flow path during molding to reduce the mold surface temperature. Japanese Patent Application No. Hei 8-08 / 98/98 discloses a mold capable of molding a high-quality, high-gloss, and warp-free plastic product without appearance defects by heating and cooling accurately and effectively in a short time. 184441, 9-
No. 3,590,022.

[0007]

However, as is apparent from the above-mentioned conventional example, the poor appearance of the product can be improved by heating the surface where the material resin flows on the visible surface side of the mold to a high temperature. If it takes a long time, the molding cycle is extended, the productivity is reduced, and the product cost is increased.

[0008] In particular, with regard to poor gloss and warpage, when a mold is heated to a high temperature and then rapidly cooled, a molded product with the highest gloss and a warped product can be obtained. For this purpose, it is necessary to perform not only rapid heating but also rapid cooling. The improvement of poor gloss is limited by the high degree of gloss that can be obtained by simply heating and molding at high temperatures.
In addition, when the temperature control accuracy is insufficient and the temperature becomes too high, the amount of shrinkage of the material resin further increases, and fillers such as glass and rubber particles such as butadiene are left on the resin surface due to post-shrinkage, resulting in poor gloss. Problem occurs again. Therefore, a mold structure capable of rapidly heating or cooling the mold surface is indispensable in order to improve the poor appearance, poor gloss, and warpage of the product.

[0009] Also, regarding the method of heating the mold surface, the above-mentioned known examples have the following problems. ,
In the case where the induction coil is provided, there are many restrictions on assembling in the mold, and the mold becomes large. In the case where the movable insert having the electric heater is provided, the insertion portion of the movable insert must be provided in the mold, which complicates the mold structure. In addition, the heating means is not versatile, and the cooling is performed by natural cooling, so that the molding cycle becomes longer.

[0010] Heating and cooling the mold surface by passing a heating and cooling medium from the external device through a temperature control medium circulation path in the mold is versatile, and the mold structure has special processing. It has the feature that it is not necessary, but when using the temperature adjustment medium circulation path in the mold in the category provided normally,
Since the heat capacity of the mold portion to be heated and cooled is large, heat loss occurs, and it takes time to heat and cool. In addition, since the response of the mold surface temperature is finally slow, there is a problem that the temperature control accuracy is deteriorated.

[0011] Further, if a portion to be heated or cooled, such as a heater or a temperature control medium circulation path, is sparse and local on the surface of the molded product, a temperature difference between the portion and the portion distant from the heated or cooled portion. And unevenness such as gloss occurs. Therefore, it is necessary for the mold to have a structure capable of rapidly heating and cooling the mold surface and a densely arranged portion for heating and cooling.

The present invention has been made in view of the above circumstances, and provides a mold capable of molding a high-quality, high-gloss, warp-free plastic product having no defective appearance, and a method of manufacturing the mold. With the goal.

[0013]

In order to achieve the above object, according to the first aspect of the present invention, a cavity that can be melted later is formed on the back surface of a thin plate for forming a molding surface according to the surface shape of a plastic product. By forming the heat medium circulation flow path forming strip with the material and forming the first coating layer on the surface of the heat medium circulation flow path forming strip, by eluting the cavity forming material from the first coating layer, The first between the sheet and the first coating layer
Forming the heat medium circulation channel to produce the molding surface member for temperature control, then incorporate this molding surface member for temperature control into the backing to make the insert, and insert the insert into the molding surface of the mold to form When manufacturing a mold that can heat or cool the mold surface sometimes, the first heat medium circulation channel forming strip has a first surface.
After forming a coating layer, the surface of the first coating layer,
A second heat medium circulating flow path forming strip is formed in the concave groove formed by the first heat medium circulating flow path forming path by using the same cavity forming material as described above. A second coating layer is formed on the surface of the road forming strip. Next, the first heat medium circulating material is eluted from the first and second coating layers forming the first and second heat medium circulating flow path forming strips on the back surface of the forming surface forming thin plate. A flow path and a second heat medium circulation flow path are formed.

Further, in the invention according to claim 2,
2. The cavity according to claim 1, wherein a first heat medium circulation channel forming strip is formed, a first coating layer is formed on the first heat medium circulation channel forming strip, and then the first heat medium circulation channel forming strip is once formed. Elute the material from within the first coating layer to form a first heat medium circulation channel,
Thereafter, a second heat medium circulation channel forming strip is formed using a cavity forming material in a concave groove on the surface of the first coating layer, and a second coating layer is formed on this surface. The second heat medium circulating flow path is formed by eluting the cavity forming material that has formed the second heat medium circulating flow path forming strip from the above.

Further, in the invention according to claim 3,
In a plastic product molding die, a first surface is formed on a back surface of a molding surface forming thin plate corresponding to a surface shape of a plastic product.
A second heat medium circulating channel is formed outside the coating layer in which the first heat medium circulating channel is formed, using a concave groove between the first heat medium circulating channels. A temperature control molding surface member having a flow path formed therein is incorporated into a backing to form an insert, and the insert is incorporated into a molding surface of a mold.

Further, in the invention according to claim 4,
According to the third aspect of the present invention, the insert piece is incorporated only in a part of the molding surface in contact with the product.

[0017]

A high-temperature heat medium is supplied and circulated in the first and second heat medium circulation channels of the insert piece incorporated in the molding surface of the mold at the time of molding. Heat. Then, when the filling is completed, the medium is switched to a low-temperature heat medium, and the low-temperature heat medium circulates in the heat medium circulation channel to rapidly cool the molding surface of the molded article. Since the heat medium circulating flow path in the molding surface member for temperature control is formed in a double dense manner, uniformity, controllability and responsiveness of the mold surface temperature distribution are improved.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION A thin plate of a molding surface member for temperature adjustment of an insert piece incorporated in a molding surface of a mold, and first and second heat medium circulating passages on the back surface thereof have, for example, a three-dimensional shape along the product shape. It is formed. When creating this temperature control molding surface member, heat capacity of the mold surface is formed by reducing the heat capacity of the mold surface portion,
Improves temperature responsiveness and temperature controllability during cooling, thereby controlling the mold surface temperature to a high temperature in a short time without prolonging the molding cycle, or controlling the mold surface temperature to a low temperature to achieve high quality and high quality without appearance defects. To form a glossy and warp-free product, forming a gap between the temperature control molding surface member and the backing,
It is advisable to produce an insert and incorporate it into all or part of the molding surface of the mold (cavity).

The feature of the mold is that a heat medium circulation flow path is formed on the molding surface of the mold along the molding surface. In particular, since the heat medium circulation channel forming strip has a limitation on the bending radius, the three-dimensional mold is not only provided with a hole in the mold material but also with a metal pipe such as copper. In the case of forming near the surface, it was difficult to arrange as desired, but in the case of the present invention, first, a heating medium circulation channel forming strip is formed on the back surface of the thin plate with wax or the like, and this surface is formed by electroforming or plating. After coating to form a coating layer, since wax and the like are melted out of the coating layer to form a flow path,
The channel can be configured at any position and with any shape and diameter. Therefore, there is no limitation on the flow path and the shape, and it can be arranged at a high density at a position close to the mold surface, and there is no problem even if it has a three-dimensional complicated shape.

Aluminum, a low-melting alloy or compound, a water-soluble polymer, or the like can be used in addition to wax as the cavity forming material for forming the flow path, as long as it can be eluted later. As a method for dissolving these materials, there is a method of immersing in an alkaline solution, heating, or the like.

The thickness between the thin plate (molding surface of the mold) and the heat medium circulating flow path is preferably as thin as possible in consideration of the mold temperature responsiveness, but the strength required for repeated molding is also required. In this case, it can be about 2 mm.

The diameter of the heat medium circulating flow path increases the Reynolds number, increases the heat exchange effect, and increases the strength with respect to the resin pressure during molding by achieving high density in the mold and increasing the flow rate of the internal fluid. It is advantageous that the diameter is smaller from the surface, and the inner diameter is preferably about 5 mm or less.

The cross-sectional shape of the heat medium circulating flow path may be any shape such as a circle, a square, an irregular shape, etc., but the second heat medium circulating path is selected due to the heat transfer and the throwing power of the electroformed layer or the plated layer. In order to prevent the cross section of the flow path from being irregular or closed, a semicircular shape having relatively uniform throwing power is desirable.

The span of the first heat medium circulating flow path depends on the diameter of the first heat medium circulating flow path.
In order to form a second heat medium circulation channel between the heat medium circulation channels,
It is desirably about 1.5 mm or more.

Next, the heat medium circulating flow path can be formed by any method, such as arranging a cavity forming material that can be eluted later from a solid state. Since the shape is formed by the heat medium circulating flow path and the first coating layer, it is desirable to form by pouring in a molten state in terms of working time, which is desirable, but it is not such a method. It may be formed by the same method as the above-described first heat medium circulation channel forming strip.

The second coating layer formed after the formation of the second heat medium circulating flow path forms a heat insulating layer and a heat resistance layer to thermally separate the backing or the mold body for controlling the temperature from the mold body, It is preferable to improve the controllability and the response of the mold surface temperature by reducing the heat capacity. In order to obtain sufficient strength against thermal stress due to resin pressure or heating and cooling during molding and shrinkage due to cooling, a void is formed between the back side of the second coating layer and the backing to provide thermal resistance, The second coating layer on the back surface side of the second heat medium circulation flow path is provided with a heat insulating property as a metal coating layer containing pores, polymers or ceramics therein, thereby achieving both durability and immediate effect of heat conduction. Good.

As the resin that can be molded using the mold according to the present invention, for example, polyethylene or polypropylene is used for a polyolefin resin, and polycarbonate or the like is used for a polyester. In the case of a styrene resin or a copolymer resin thereof, polystyrene, polyacrylonitrile styrene, polyacrylonitrile butadiene styrene, or the like is used. Furthermore,
It is preferable to use a vinyl chloride resin such as vinyl chloride, various kinds of polyamide resins such as nylon and acrylic resin. Of course, these alloys or blended resins may be used.

In addition to the resin, naturally, various antioxidants, heat stabilizers, and ultraviolet absorbers which are usually added to the resin are included, and dyes and pigments, or some reinforcing materials such as glass fiber and carbon fiber are included. Alternatively, other inorganic substances may be added.

As described above, the mold surface temperature can be accurately determined.
Using a mold for injection molding of plastic products that can be heated and cooled effectively and uniformly in a short period of time, the surface temperature of the mold on the visible side of the product can be rapidly increased to near the glass transition temperature if the resin is non-crystalline when filled with resin. After heating, quenching and injection molding to lower the mold temperature are usually performed because a solidified layer hardly develops and easily deforms on the resin surface in contact with the mold surface on the high-temperature product visible side. At a low mold surface temperature, a solidified layer is rapidly developed and formed on the resin surface, and the appearance of the product, such as a flow mark or weld, which is formed and stored, does not occur.

Further, since the resin is sufficiently adhered to the mold surface and the transferability is good, the release of the resin is delayed, and the solidified layer develops to a sufficient strength during this time. Inferior appearance caused on the product surface due to heat shrinkage, for example, due to depression of sink marks, or filler such as glass or other small shrinkage in material resin, or rubber particles such as butadiene selectively remaining on the resin surface. A high-quality molded product free from poor gloss and no appearance defect can be obtained.

In particular, regarding the gloss, when the mold temperature control accuracy is insufficient and the temperature is too high, the amount of shrinkage of the material resin further increases, and filler such as glass, rubber such as butadiene or the like due to post-shrinkage or the like. There is a concern that poor gloss may occur again due to the particles being left on the resin surface, but the mold according to the present invention has a good response and controllability of the surface temperature, so that a stable and high-gloss molded article can be obtained. can get.

Further, when the mold surface is molded at a high temperature, if the cooling is slow, the molded product is likely to be deformed such as warping, but the mold surface according to the present invention can rapidly cool the mold surface. Therefore, the molded product does not warp or deform. Moreover,
Since the heating and cooling of the mold surface can be accurately achieved in a short time, the molding cycle is not extended and the mass productivity is not impaired.
High quality molded products can be obtained at low cost.

[0033]

Embodiment 1 A member for forming a heat medium circulation channel on a molding surface of a mold is manufactured through the steps shown in FIG. First,
As shown in FIG. 1A, a thin plate 2 made of nickel and having a thickness of about 2 mm is formed on the surface of the master 11 by electroforming. Next, as shown in FIG.
The first heat medium circulation channel forming strips 5 for forming the first heat medium circulation channel are formed on the back surface of the first wax layer 3. next,
As shown in (C), the electroformed layer 1 filled with the electroforming solution 12 '
The first coating layer (nickel layer) 7 is formed on the surface of the wax layer 3 by dipping the thin plate 2 together with the master 11 into the inside 2. In the figure, reference numeral 13 denotes an electrode. Next, as shown in (D), a second heat medium circulating flow path forming line 6 for forming a second heat medium circulating flow path is formed on the surface of the formed first coating layer 7 by the wax layer 4.
Formed. Next, similarly to (C), as shown in (E), the master 11 is immersed together with the master 11 in the electroformed layer 12 filled with the electroforming solution 12 ′, so that the second coating layer (nickel A layer 8 is formed. Next, as shown in (F),
By applying heat to the first wax layer 3 and the second wax layer 4 to elute the first and second wax layers 3 and 4 from within the first coating layer 7 and the second coating layer 8, the thin plate 2 and the first Coating layer 7
And a cavity between the second coating layer 8, that is, the first heat medium circulation channel 9
And the 2nd heat medium circulation channel 10 is formed, and the molding surface member 1 for temperature control is obtained. Next, as shown in (G), the insert member 15 is manufactured by incorporating the molding surface member 1 for temperature control into the backing 14, and the insert member 15 is incorporated into the molding surface in the mold. At this time, a gap 18 was formed between the backing 14 and the molding surface member 1 for temperature control by electric discharge machining.

[0034]

[Embodiment 2] This embodiment is an embodiment in which the insert piece 15 manufactured in Embodiment 1 is integrated into a molding surface of a mold 20. FIG. 3 is the insertion piece 15
FIG. 4 is a sectional view taken along line AA '.

The plastic product injection molding mold 20 shown in FIG. 2 is roughly divided into a core (product invisible surface side) 21 and a cavity (product visible surface side) 22 and both are connected to an injection molding machine (not shown). Core 21 and cavity 2
2 can be opened and closed. Core 21 and cavity 22
Is formed with a concave portion 23 corresponding to the outer shape of the product.
Molten plastic is poured into the concave portion 23 from an injection molding machine (not shown) via 4 to form a product.

The product visible side (cavity 22) of this product
On the other hand, a mold piece 15 for rapid heating and cooling of the mold surface is incorporated, and a first heat medium circulation channel 9 and a second heat medium circulation flow formed on the back surface of the thin plate 2 of the mold piece 15. Due to the heat medium flowing in the passage 10, the resin is rapidly heated at a high temperature at the time of filling, and then rapidly cooled and solidified at a low temperature, and thereafter taken out of the mold 20. The heat medium flowing through the first heat medium circulation flow path 9 and the second heat medium circulation flow path 10 is supplied from a medium temperature controller that has a high-frequency heater and a cooler (not shown) and can perform rapid heating and cooling. Is done.

FIG. 3 and FIG. 4 show an insert piece to which the temperature control molding surface member 1 in which the first heat medium circulation channel 9 and the second heat medium circulation channel 10 for rapid heating and cooling of the mold surface are formed is fixed. 15 is an explanatory view of FIG. 15, wherein the thin plate 2 in contact with the product visible surface is formed of Ni—Cr, and inside the first heat medium circulation flow path 9 and the heat medium inflow port 16 and the heat medium outflow port 17, respectively. A second heat medium circulation channel 10 is formed. The first heat medium circulation flow path 9 and the second heat medium circulation flow path 10 are provided on the inner surface of the thin plate 2 in the mold.
After forming the conduit, the first coating layer 7 is formed on the surface with the electroformed layer, and the second wax layer 4 is formed in the concave void formed on the surface of the first coating layer 7 with the second wax layer 4. After forming the conduit, the second coating layer 8 is formed by electroforming.

Thereafter, the wax layer 3 and the wax layer 4 are eluted from the inside of the first coating layer 7 and the second coating layer 8, and the inside of the first coating layer 7 and the second coating layer 8 is hollowed out. And integrated with it.

The cross-sectional shape of the first heat medium circulation channel 9 and the second heat medium circulation channel 10 is a semicircle with a radius of 2.5 mm, and the pitch is 15 mm. The distance between the first heat medium circulation flow path 9 and the second heat medium circulation flow path 10 and the surface of the mold insert 15 for rapid heating and cooling of the mold in contact with the product is equal to the first heat medium circulation flow path 9 and the second heat medium circulation flow path. The distance between the heat medium circulation channel 10 and the surface of the mold surface 15 for rapid heating and cooling of the mold in contact with the product is 2.5 mm in the first heat medium circulation channel 9 and 4 mm in the second heat medium circulation channel 10. 5 mm.

Using the molds shown in FIGS. 2 to 4, using an ABS resin (15G20, glass transition temperature 98 ° C., Nippon Synthetic Rubber) containing 20% glass filler, filling the mold surface temperature on the visible side of the product with the resin. Injection molding was performed by rapidly heating and cooling to 100 ° C. and 60 ° C. during cooling. The molding cycle (injection-holding pressure-cooling-removal) at this time was 55 seconds, the time required for heating was 15 seconds, and the time required for cooling was 20 seconds.

The gloss measurement result of the visible surface of the product is 9
5 (1G-31D, using a gloss meter manufactured by Horiba Seisakusho), and a high-gloss product was obtained despite inclusion of a glass filler. Further, at the time of taking out the product, the product was sufficiently solidified, and there was no problem of deformation and release of the product. When the heating was completed, the temperature difference between the first heat medium circulation flow path 9 on the product visible surface side mold surface and the first heat medium circulation flow path 9 was measured, and the temperature difference was 0.4 ° C. .

[0042]

Example 3 Using the same apparatus as in Example 2 and impact-resistant polystyrene (HT560, glass transition temperature 97 ° C, Idemitsu Petrochemical), the surface temperature of the mold on the visible side of the product was measured at the time of resin filling.
Injection molding was performed by rapidly heating and cooling to 00 ° C and 60 ° C during cooling. The molding cycle (injection-holding pressure-cooling-removal) at this time was 55 seconds, the time required for heating was 15 seconds, and the time required for cooling was 20 seconds.

The mold surface on the product invisible surface side is provided with a boss and a rib-shaped engraving and a mold surface on the product visible surface side so as to easily cause appearance defects such as sink marks and welds on the molded product. Molding was performed by providing a push-off projection.

The visible surface of the obtained molded article has no appearance defects such as sink marks, welds and flow marks, and has a gloss of 9
A high quality product with a high gloss of 7 was obtained. No deformation such as warpage was observed in the product.

[0045]

Embodiment 4 The present embodiment relates to a means for forming the second heat medium circulating flow path 10. The second layer of the first embodiment is made by pouring a wax. The second heat medium circulation channel forming strips 6 are formed by arranging circular waxes,
This is an example in which the coating layer 8 is formed and then eluted to form the second heat medium circulation channel 10.

[0046]

Comparative Example 1 Insert 1 for Rapid Heating and Cooling of Mold Surface of Example
The same apparatus and resin as in Example 2 were used, except that 5 was made of S55C and the heat medium circulating flow path 9 was replaced with an insert which simulates a normal mold structure in which two heat-medium circulation channels 9 were machined into a horizontal hole. The same mold surface temperature at the visible side of the product at the time of filling is 100 ° C, and when cooling, 6
The molding was performed under the temperature condition of 0 ° C. The molding cycle (injection-holding pressure-cooling-removal) at this time was 84 seconds, the time required for heating was 39 seconds, and the time required for cooling was 40 seconds, which was 50% longer than the molding cycle. Also, the gloss measurement result of the visible surface of the product was 88, which was lower than that of the product of Example 2. Conversely, when the molding cycle was set to 55 seconds, the same as in Example 2, the product gloss was extremely low, the product temperature at the time of removal was high, and the product was easily deformed.

[0047]

Comparative Example 2 Insert 1 for Rapid Heating and Cooling of Mold Surface of Example
5 was replaced with an insert that simulates a normal mold structure made of S55C and having two heat medium circulation passages 9 in the form of side holes. Injection molding was performed at the same visible surface side mold surface temperature of 100 ° C. and cooling at 60 ° C. The molding cycle (injection-holding pressure-cooling-removal) at this time was 84 seconds, the time required for heating was 39 seconds, and the time required for cooling was 40 seconds, which was 50% longer than the molding cycle. The gloss measurement result of the visible surface of the product was also lower than the gloss 91 and the product gloss of Example 3, and the product was significantly warped and deformed.

[0048]

Comparative Example 3 Insert 1 for Rapid Heating and Cooling of Mold Surface of Example
After the first coating layer 7 of No. 5 was formed, the same apparatus and resin as those in Example 2 were used except that the heat medium circulation flow path manufactured by assembling in the backing 14 was replaced with a single-piece insert. Injection molding was performed by rapidly heating and cooling the mold surface temperature to 100 ° C. during resin filling and 60 ° C. during cooling. At this time, the molding cycle (injection-holding pressure-cooling-unloading) is 65 seconds,
The time required for heating was 20 seconds, and the time required for cooling was 25 seconds. The gloss measurement result of the visible surface of the product is
And a high gloss product similar to that of Example 2, but with a 18% longer molding cycle.

The molding cycle was the same as that of the second embodiment.
In the case of seconds, gloss unevenness occurred along the heat medium circulating flow path on the visible surface of the product, and was lower than the gloss 88 and the gloss of Example 2. Further, when the heating was completed, the temperature difference between the heat medium circulating flow path 9 and the heat medium circulating flow path 9 on the product visible surface side mold surface was measured. As a result, the temperature difference was as large as 4.1 ° C.

[0050]

According to the above-mentioned mold, not only general-purpose resin but also
High gloss, high quality and no warpage can be obtained even with resin molded products containing fillers such as glass and rubber particles such as butadiene, which were previously considered difficult to obtain high gloss product surfaces. The advantages are great in terms of quality, cost and cost, and the effect in reducing product defects is extremely large (claims 1 to 4).

Next, the present invention reduces the heat capacity on the mold side by forming a gap serving as thermal resistance between the temperature control molding surface member and the backing, thereby quickly heating and cooling quickly. (Claims 1 to 4).

Further, by forming the second coating layer itself on the opposite side of the molding surface of the heat medium circulating flow path from a metal layer containing pores, polymers or ceramics therein, this is formed into a heat insulating layer or a heat insulating layer. By making the heat resistance layer and reducing the heat capacity of the mold side, rapid heating and rapid cooling can be performed immediately, and in the case of a void, a heat insulating layer proposed by the present inventors is formed. Compared with JP-A-8-184441 (Claim 11), the mold manufacturing cost and the weight can be reduced (Claims 1 to 4).

[Brief description of the drawings]

FIG. 1 is an explanatory view of a method for manufacturing a mold according to the present invention.

FIG. 2 is a sectional view showing an example of an injection mold according to an embodiment of the present invention.

FIG. 3 is an explanatory view of a heat medium circulating flow path and an insertion piece.

FIG. 4 is a sectional view taken along line AA ′.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Molding surface member for temperature control 2 Thin plate 3 1st wax layer 4 2nd wax layer 5 1st heat medium circulation channel formation line 6 2nd heat medium circulation channel formation line 7 1st coating layer 8 2nd coating layer 9th 1 Heat Medium Circulation Channel 10 Second Heat Medium Circulation Channel 11 Master 12 Electroformed Layer 13 Electrode 14 Backing 15 Insert 16 Heat Medium Inlet 17 Heat Medium Outlet 18 Void 20 Mold

Claims (4)

[Claims] 1. A heat medium circulating flow path forming strip is formed on a back surface of a molding surface forming thin plate according to a surface shape of a plastic product by a cavity forming material that can be melted later, and the heat medium circulating flow path forming sheet is formed. After forming the first coating layer on the surface of the strip,
The cavity forming material is eluted from the first coating layer to form a first heat medium circulation channel between the thin plate and the first coating layer to produce a temperature control molding surface member. The first heat medium circulation when manufacturing a mold capable of heating or cooling the mold surface during molding by incorporating the member into the backing to form an insert piece and incorporating the insert piece into the molding surface of the mold; After forming the first coating layer on the surface of the flow path forming strip, the same cavity as above is formed in the concave groove formed on the surface of the first coating layer and formed by the first heat medium circulation flow path forming strip. Forming a second heat medium circulating channel forming strip using the forming material, and further forming a second coating layer on the surface of the second heat medium circulating channel forming strip; The elution of the cavity forming material from the first and second coating layers forming the heat medium circulating flow path forming strips results in a molding surface. The on the back surface of the formed thin plate 1 heating medium circulation flow path and the second
A method for manufacturing a plastic product injection molding mold, comprising forming a heat medium circulation channel. 2. A first heat medium circulation channel forming strip is formed, and a first coating layer is formed on the first heat medium circulation channel forming strip. The first heat medium circulation channel is formed by eluting from the inside of the coating layer, and then the second heat medium circulation channel forming line is formed by using the cavity forming material in the concave groove on the surface of the first coating layer. After forming the second coating layer on the surface, the second heat medium circulation channel is formed by eluting the cavity forming material forming the second heat medium circulation channel forming strip from inside the second coating layer. The method for producing a plastic product injection molding mold according to claim 1. 3. A first heat medium circulating flow path is formed on the back surface of a molding surface forming thin plate conforming to the surface shape of a plastic product, and the first heat medium circulating flow path is formed outside the coating layer on which the first heat medium circulating flow path is formed. The second heat medium circulation channel using the concave groove between the first heat medium circulation flow path.
A mold for molding a plastic product, in which a temperature control molding surface member having a heat medium circulation channel formed therein is incorporated into a backing to form an insert, and the insert is incorporated into a mold molding surface. 4. The mold for molding a plastic product according to claim 3, wherein an insert piece is incorporated only in a part of the molding surface in contact with the product.