JP2010274488A - Mold for evaluating injection moldability of thermosetting resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold capable of evaluating the effect on resin filling property (method for involving bubbles) by changing the filling direction to the mold so as to evaluate variation in the molded articles with the same mold by assuming multi-cavity molding in consideration of high-volume production. <P>SOLUTION: The mold for evaluating injection moldability of a liquid thermosetting resin has a feature wherein (1) there are at least two or more cavities having same shape in the mold, (2) there are a gate and a runner part so that the all cavities are located at the same distance from the filling start part of the resin, and (3) there are no air vent and overflow groove in the final filling part of the cavity. Furthermore, it is preferable that (4) there is no ejector pin in a filling route of the resin such as the cavities, the runner part, and the gate. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a mold capable of evaluating moldability during injection molding of a thermosetting resin.

  As an optical material having high transparency and high heat resistance, a glass material has been generally used. However, in recent years, a thermosetting resin material is used from the viewpoint of low workability, cost, and weight reduction of the material. Are beginning to be used. These thermosetting resins are generally molded and commercialized using a horizontal injection molding machine or the like in the same manner as thermoplastic resins. However, since the viscosity of the thermosetting resin of the resin before filling the mold is very low compared to the thermoplastic resin in the molten state, it is easy to entrain air when filling the mold, and the final filling part of the product, etc. It is also a feature that it is easy to leave a bubble bite.

  It is known that the entrainment of air at the time of filling is affected by the viscosity of the resin, molding conditions, or how to provide a mold air vent. For example, Patent Document 1 or Patent Document 2 includes a plurality of cavities. Attempts have been made to evaluate the filling property of the resin using a mold provided with recesses.

  On the other hand, for such molded products by injection molding, since the cycleability of the molding and the large number of pieces are important for mass production, the runner system is diversified. However, since thermosetting resin has a low resin viscosity, in the case of a mold of a generally known horizontal injection molding machine, it corresponds to a product part with respect to a sprue part or a cold runner part corresponding to a resin starting position. A phenomenon occurs in which the resin filling method differs depending on whether the cavity is on the upper side or the lower side. That is, when the resin is filled upward into the cavity, the liquid level remains horizontal and the cavity is filled in order to resist gravity.

  However, when the cavity is filled downward, the resin that has reached the cavity tends to be filled along the wall surface due to the action of gravity. This is because, for example, when a multi-cavity mold that molds a plurality of molded products of the same shape at a time is used, the appearance of the final molded product (surface properties and entrainment of bubbles) depends on the filling direction. Existence) and physical properties (product dimensions) may be affected.

JP-A-8-244071 Japanese Patent Laid-Open No. 9-39056

  Therefore, in view of the above circumstances, an object of the present invention is a mold that can evaluate the influence on resin filling properties (how to entrain foam) by changing the filling direction of the mold, Assuming multi-cavity molding that is conscious of mass production, it provides that the variability of molded products can be evaluated with the same mold.

  That is, the present invention has the following configuration.

1). A mold for molding a resin,
(1) There are at least two cavities of the same shape in the mold.
(2) There are a gate and a runner part so that all the cavities exist at the same distance from the resin filling start part.
(3) There are no air vent and overflow groove in the final filling part of the cavity,
A mold for evaluating the injection moldability of a liquid thermosetting resin.

  2). The mold for evaluating the injection moldability of a liquid thermosetting resin according to 1), wherein no ejector pin is present in the filling route.

  3). The mold for evaluating the injection moldability of the liquid thermosetting resin according to 1) or 2), wherein uneven portions are provided in each cavity.

  4). When the maximum width of the cavity on the side where the cavity and the gate are connected is (X) and the gate width of the connecting portion between the cavity and the gate is (Y), the relationship is (Y) <(X) / 2 1) ~ 3) A mold for evaluating the injection moldability of the liquid thermosetting resin according to any one of the above.

  5). The injection moldability of the liquid thermosetting resin according to any one of 1) to 4), wherein the E-type viscosity of the liquid thermosetting resin measured at 23 ° C. is in the range of 0.1 to 100 Pa · s. Evaluation mold.

  When the injection mold according to the present invention is used, the influence on the filling property by the filling direction of the resin and the product variation for each molding shot can be evaluated, so that it is useful in producing a mold for optical parts.

It is an example of the metal mold | die used by this invention, and is a metal mold | die top view at the time of attaching to a movable side so that resin may be filled upward. It is an example of the metal mold | die used by this invention, and is a metal mold | die top view at the time of attaching to a movable side so that resin may be filled downward. It is an example of the metal mold | die used by this invention, and expands one part of the cavity part shown by FIG. 1, FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2 are plan views of an injection mold according to the present invention. FIG. 1 shows a case where the cavity is installed on the movable side of the injection molding machine so that the cavity is filled upward, and FIG. 2 shows that the cavity is installed on the movable side of the injection molding machine so that the cavity is filled downward. Is the case. FIG. 3 is an enlarged view of a part of the plurality of cavities shown in FIG.

  Normally, a mold has a fixed side and a movable side with a parting line as a pair, but FIGS. 1 and 2 show the movable side, especially the molding part, runner part, and gate part only. Is shown. In the present invention, the fixing side surface is not particularly shown, but it is preferable that there are only holes (pinholes) for filling the resin, and there are no cavities, runners, gates, and the like.

  The cavity surface including the runner part and the gate part shown in FIG. 1 may be directly carved into the movable side surface, and when the movable side surface is a main mold called a base plate and a method of nesting inside The cavity surface may be carved into the nest. In the mold plan view of FIG. 1, four cavities having the same shape are provided. However, the number of cavities is not particularly limited, and the number of cavities can be arbitrarily set, but the moldability of the present invention is evaluated. For this purpose, it is preferable that there are a plurality of them, and the shape of the resin is preferably the same because the filling property of the resin is uneven.

  In the present invention, it is preferable that all of these cavities exist at the same distance from the resin filling start portion 2 through the runner portion 3. Here, the same distance means that the resin reaching the cavity reaches the corners, preferably in contact with the same number of corners, through the runner portions and gates having the same width, depth and distance.

  In order to make the distance of the runners the same, it is conceivable to provide the runner portions radially (concentrically) from the resin filling start portion, but in this case, the inclination angle differs depending on the runner portions, which is not preferable. Actually, as shown in FIG. 1, the runner portion preferably takes a route like a tournament.

  In the present invention, the portion corresponding to the final filling portion 4 of the cavity does not have a bubble vent (bubble vent) air vent, a vacuum vent, or an overflow groove that is normally provided. If these vents and grooves are not provided, and if the path is a bag path, when the curable resin is filled with the air that is present in the mold from the beginning, depending on the filling direction or molding conditions, the filling amount and the method of entraining the foam Can be evaluated. It is preferable that there is no air vent, vacuum vent, or overflow groove in the cavity, not limited to the final filling portion 4 of the cavity.

  In the mold of the present invention, it is preferable to avoid installing an ejector pin in a resin filling route such as a cavity, a runner part, and a gate. As for the movable side surface of a general mold, there is an ejector pin that is a protruding mechanism in order to release the molded product. However, since the curable resin used in the present invention is a low-viscosity liquid, if there is an ejector pin, etc., the resin will enter the sliding part (gap), and unevenness due to the ejector pin will result in filling the cavity. May cause non-uniformity.

  However, an ejector pin may be provided when it is not necessary to reduce the degree of unevenness due to the sliding portion (gap) and the ejector pin, or to consider these problems. Moreover, you may provide an ejector pin also with the viscosity of resin to fill.

  In addition, about the mold release of the molded article when an ejector pin is not provided, an air blower, a rubber sucker, or a mold release method by vibration can be employed.

  The injection mold satisfying these conditions is filled with a liquid thermosetting resin from the resin filling start part 2, so that the resin is filled into each cavity 1 via the runner part 3, and the final filling part 4. Will be satisfied. The filling direction can be evaluated in the upward filling direction when the mold is attached to the movable side surface as shown in FIG. 1, and the evaluation in the downward filling direction is possible when the die surface is attached as shown in FIG. It will be possible.

  The mold of the present invention is provided with a recess or projection (irregular portion) for measuring the shrinkage ratio of the molded product in the cavity, and an uneven portion formed by transferring the uneven portion of the mold to the molded product. By measuring (the length in the case of obtaining the shrinkage ratio of the plane), the shrinkage ratio of the molded product can be easily obtained. By providing the concavo-convex portion in the cavity, the shrinkage rate of the molded product can be measured simultaneously with the moldability evaluation, which can be used for checking the mold design and molding conditions.

  It is preferable to reduce the depth (height) of the concavo-convex portion in order to reduce the influence on the fluidity of the resin. It is also preferable to reduce the size. From the viewpoint of ease of measurement of the obtained molded product and little influence on the resin flow, the concave portion is preferable.

  As for the shape of the concavo-convex portion, it is preferable to provide a cross shape, preferably a dot shape, at both ends of the length portion to be measured. The part to be measured is not limited to one place, and a plurality of places may be received in some cases. Further, in order to obtain the directionality of the shrinkage rate, it is preferable to provide a concavo-convex portion so that measurement can be performed by changing the directionality of the portion to be measured.

  A specific recess may be engraved. The concave portion here refers to a mark engraved to serve as a mark on the cavity side. The shape and size of the mark can be set as desired, but it is important to engrave within the extent that the recesses engraved on the side of the mold become protrusions on the surface of the molded body after thermosetting resin molding. is there.

In FIG. 1 of the present invention, a cross is engraved as shown in the recess 5 as an example. In addition, the convex part transcribe | transferred to the molded article is the main objective to perform a dimension measurement (molding shrinkage rate),
By comparing the dimensions of a plurality of molded products, it is possible to evaluate the variation between the molded products obtained for each molding shot.

  In the mold of the present invention, as shown in FIG. 3, the relationship between the maximum width (X) of the cavity 1 and the width (Y) of the contact portion 6 between the cavity and the gate is (Y) <(X) / 2. It is preferable to become. Since the gate width (Y) is smaller than the cavity width (X), it is possible to evaluate the entrainment of bubbles in the corner 7 on the side near the gate shown in FIG.

  In FIG. 3, the gate is shown to have the same width as the runner portion, but the gate may be narrowed like a normal injection mold.

  As the thermosetting resin molded using the injection mold in the present invention, a generally known liquid thermosetting resin can be arbitrarily used. Although any thermosetting resin can be used, a thermosetting resin having a viscosity measured by an E-type viscometer at 23 ° C. in the range of 0.01 to 1000 Pa · s is preferably used.

  Examples and Comparative Examples of the present invention are shown below, but the present invention is not limited to the following.

(Examples 1-6)
A silicone-based liquid thermosetting resin (viscosity at 23 ° C .: 2.0 Pa · s) was used for injection molding under the following molding conditions. When molding was stabilized, a molded product for evaluation was obtained, and the filling results are shown in Table 1.

Injection molding machine: Liquid injection molding machine with a mold closing force of 40t (manufactured by Sodick Plustec)
Mold temperature and curing time: 135 ° C x 120 seconds Mold filling direction: Both upward and downward runners, Gate width: 4mm
Runner, gate depth: 0.5mm
Cavity size: 10 mm x 20 mm (thickness 0.5 mm)
Weighing when fully filling the cavity: 3 mm in the cylinder position Injection pressure: 1.00 MPa.

  When the metering was adjusted to be unfilled as in Example 1 and Example 4 in Table 1 and the injection speed was low, the resin was filled from the vicinity of the gate regardless of the upward or downward filling direction. As in Example 2 and Example 5, the metering was adjusted so that full filling was possible, and when the injection speed was low, filling was performed from the vicinity of the gate, and bubbles remained at the corner of the final filling part. In Example 3, the injection speed was higher than that in Example 1, but the filling method was the same as in Example 1. On the other hand, when the injection speed was increased downward as in Example 6, unlike Example 3, the resin was filled from the final filling portion along one side wall near the gate.

(Examples 7 to 8)
Using the same silicone-based liquid thermosetting resin as in Example 1, injection molding was performed under the following molding conditions. When molding was stable, an evaluation molded product was obtained, and the distance between protrusions (intercross) (die actual size 6.00 mm) engraved in the evaluation molded product was measured (at 23 ° C.) with a micro high scope. (Average value for 5 molded products).

Injection molding machine: Liquid injection molding machine with a mold closing force of 40t (manufactured by Sodick Plustec)
Mold filling direction: Metering during upward injection: 3 mm in the cylinder position Mold temperature and curing time: 135 ° C. × 120 seconds, 150 ° C. × 30 seconds Injection pressure: 1.00 MPa.

Since four evaluation molded products are obtained by one shot of injection molding, names A to D are given, and the results are shown in Table 2.
As shown in Table 2, the dimensions of the samples were almost the same in both Example 7 and Example 8. It was found that the dimensions were smaller when the mold temperature was raised as in Example 8.

1: Cavity 2: Resin filling start part 3: Runner part 4: Final filling part 5: Recess 6: Contact part between gate and cavity 7: Corner inside cavity near gate

Claims (5)

A mold for molding a resin,
(1) There are at least two cavities of the same shape in the mold.
(2) There are a gate and a runner part so that all the cavities exist at the same distance from the resin filling start part.
(3) There are no air vent and overflow groove in the final filling part of the cavity,
A mold for evaluating the injection moldability of a liquid thermosetting resin. 2. The mold for evaluating the injection moldability of a liquid thermosetting resin according to claim 1, wherein there is no ejector pin in the filling route. 3. The mold for evaluating the injection moldability of a liquid thermosetting resin according to claim 1, wherein an uneven portion is provided in each cavity. The relationship of (Y) <(X) / 2 is established, where (X) is the maximum width of the cavity on the side where the cavity and the gate are connected, and (Y) is the gate width of the connection portion between the cavity and the gate. A mold for evaluating the injection moldability of the liquid thermosetting resin according to any one of 1 to 3. 5. The injection moldability of a liquid thermosetting resin according to any one of claims 1 to 4, wherein the E-type viscosity of the liquid thermosetting resin measured at 23 ° C is in the range of 0.1 to 100 Pa · s. Evaluation mold.

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