JP2018069563A - Composite molded article and process for producing the same, and mold for producing composite molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite molded article having a thick portion and having high dimensional accuracy, a method of producing the same, and a mold for producing a composite molded article.SOLUTION: In a presence of an inner layer member 1, an outer layer 2 covering at least a part of the inner layer member 1 is formed by injection molding of a first resin composition. There is an outer layer forming step for forming a composite molded body 100 having an inner layer and the outer layer 2 composed of the inner layer member 1. At least a part of the thickness of the composite molded body 100 is 5.0 mm or more, the inner layer member 1 has at least one of a surface 1a and a surface 1b, and in the outer layer forming step, a surface 2a of the outer layer 2 covers at least a part of the surface 1a, a surface 2b covers at least a part of the surface 1b. When a distance between the surface 2a and the surface 1a closest to the surface 2a is a, and a distance between the surface 2b and the surface 1b closest to the surface 2b is b, a and b satisfy following formulas I to III. 1.2≤b/a≤2.0...I 0.5 mm≤a≤2.0 mm...II 0.6 mm≤b≤3.0 mm...III.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a composite molded body, a method for producing the same, and a mold for producing a composite molded body.

In general, an injection molding method is known as a method for producing various resin products such as automobile parts, electric / electronic parts, and housings. The injection molding method is a method in which a resin is melted and molded into a desired shape by injection filling into a mold having a cavity through a sprue, a runner and a gate, and a resin product is manufactured at a low cost. It can be used widely.
However, since the resin shrinks when it is cooled and solidified from the molten state, sink marks such as dents and holes may occur in the molded body obtained by the injection molding method. Therefore, in the injection molding method, it is necessary to devise to obtain a molded body with high dimensional accuracy by preventing sink marks. For example, the mold can be designed in anticipation of the shrinkage rate of the resin, the pressure during injection can be increased to increase the amount of resin filled in the mold to make it difficult to shrink, or the resin can be added with an inorganic filler. Ingenuity has been made to reduce the effects of shrinkage. In particular, when obtaining a molded body having a thick portion, since the absolute amount of shrinkage is increased due to the large amount of resin constituting the thick portion, it becomes more difficult to obtain a molded body with high dimensional accuracy. Therefore, as a method for improving the dimensional accuracy of a molded body having a thick portion, the thick layer is formed by two-stage injection molding (double molding) in which an inner layer is primary molded and a thin outer layer is secondarily molded around it. There exists a technique made into a composite molded object (patent documents 1-3).
JP 2016-130463 A JP 2007-002690 A Japanese Patent Publication No. 07-099341

  An object of the present invention is to provide a composite molded body having a thick portion and high dimensional accuracy, a manufacturing method thereof, and a mold for manufacturing the composite molded body.

  In the process of studying a method for further improving the dimensional accuracy of a molded body having a thick portion, the present inventor performs injection molding such as double molding multiple times, thereby forming the molded body at each time, particularly the outermost layer. Although the thickness of the molded product can be reduced and the absolute amount of overall shrinkage can be suppressed, especially when a crystalline thermoplastic resin is used, the portion on the resin injection port side of the molded product of the outer layer and its opposite It has been found that the side (the flow end side of the resin) may be different in size from each other or the plane positions of both end faces may be shifted with respect to the desired shape. That is, when the inner layer member is injection-molded so as to be covered with the outer layer molded body, the resin constituting the outer layer is injected into the cavity from the resin injection port of the mold and contacts the inner layer member disposed in the cavity. The space formed between the cavity and the inner layer member flows along the inner layer member, wraps around the inner layer member, and is filled on the opposite side of the resin injection port (resin flow end side), but in particular, the portion in contact with the inner layer member It has been found that desired dimensional accuracy may not be obtained in the (resin inlet side portion) and the opposite side portion (resin flow end side portion). Further research was conducted, and the knowledge that the difference in the position of the inner layer member (primary molded body) in the portion covered with the outer layer (secondary molded body) affects these dimensional accuracy was obtained. Then, the present inventor considered that the thickness of the outer layer (secondary molded body) is such that the outer layer has a resin inlet side (the resin inlet side of a mold used for injection molding of the outer layer) and the opposite side (the resin flow end side). ) And the inner layer member (primary molded body) at a position where the ratio of both falls within the predetermined range, even when a crystalline thermoplastic resin is used, The present inventors have found that the dimensional accuracy can be improved by preventing the difference between the size of the portion and the portion on the opposite side and the planar position, thereby completing the present invention.

That is, in the method for producing a composite molded body according to the present invention, the first resin composition is injection-molded in the presence of the inner layer member to form an outer layer that covers at least a part of the inner layer member, and includes the inner layer member. A surface 1a having an outer layer forming step of obtaining a composite molded body having an inner layer and the outer layer, wherein the thickness of at least a part of the composite molded body is 5.0 mm or more, and the inner layer members face opposite sides to each other; And at least one surface 1b, and in the outer layer forming step, the surface 2a on which the trace of the resin injection port of the outer layer is formed covers at least a part of the surface 1a and faces away from the surface 2a 2b covers at least a part of the surface 1b, and the distance between the surface 2a and the surface 1a closest to the surface 2a is a, and the distance between the surface 2b and the surface 1b closest to the surface 2b Is b, a and b are So as to satisfy the following formula I to III, characterized in that the outer layer is formed.
1.2 ≦ b / a ≦ 2.0. . . I
0.5 mm ≦ a ≦ 2.0 mm. . . II
0.6 mm ≦ b ≦ 3.0 mm. . . III

  In this invention, after the said outer layer formation process, it can comprise so that the dimension adjustment of the said composite molded object may not be performed. Moreover, before the said outer layer formation process, it can comprise so that it may have the inner layer formation process which injection-molds a 2nd resin composition and forms the said inner layer member.

  In the present invention, it is preferable that the first resin composition and the second resin composition have heat-fusibility. It is preferable that the first resin composition and the second resin composition contain a crystalline thermoplastic resin. It is preferable that the second resin composition contains an inorganic filler and the first resin composition does not contain a fibrous inorganic filler.

The composite molded body according to the present invention is a composite molded body having an inner layer and an outer layer that covers at least a part of the inner layer and includes the first resin composition, and at least a part of the thickness is 5.0 mm or more. The inner layer has at least one surface 1a and a surface 1b facing away from each other, and the outer layer has a surface 2a having a trace of a resin injection port and a surface 2b facing away from the surface 2a. The surface 2a covers at least part of the surface 1a, the surface 2b covers at least part of the surface 1b, and the distance between the surface 2a and the surface 1a closest to the surface 2a is a When the distance between the surface 2b and the surface 1b closest to the surface 2b is b, a and b satisfy the following formulas I to III.
1.2 ≦ b / a ≦ 2.0. . . I
0.5 mm ≦ a ≦ 2.0 mm. . . II
0.6 mm ≦ b ≦ 3.0 mm. . . III

  In the present invention, it is preferable that the inner layer includes a second resin composition.

The mold for producing a composite molded body according to the present invention is an outer layer forming mold for forming an outer layer that covers at least a part of the inner layer member by injection molding the first resin composition in the presence of the inner layer member. The outer layer forming mold includes a cavity filled with the first resin composition through a resin injection port, and a holding part for holding the inner layer member in the cavity, and the cavity The inner layer member has at least one surface 1a and surface 1b facing opposite to each other, and the holding portion is a resin inlet for the outer layer to be obtained. The surface 2a on which the traces are formed covers at least a part of the surface 1a, the surface 2b facing away from the surface 2a is a position covering at least a part of the surface 1b, and the surface 2a and the surface 2a The distance from the surface 1a closest to the surface 2a is a, and the surface 2 And the distance between nearest the surface 1b to said surface 2b when the b, a and b, characterized in that to hold the inner member in a position that satisfies the following formula I to III.
1.2 ≦ b / a ≦ 2.0. . . I
0.5 mm ≦ a ≦ 2.0 mm. . . II
0.6 mm ≦ b ≦ 3.0 mm. . . III

  In this invention, it is preferable that the said holding | maintenance part is comprised so that the position of the said inner layer member can be changed. Moreover, it can comprise so that it may have an inner layer formation metal mold | die for injection-molding the 2nd resin composition and forming the said inner layer member.

  ADVANTAGE OF THE INVENTION According to this invention, the composite molded object which has a thick part and has high dimensional accuracy, its manufacturing method, and the metal mold | die for composite molded object manufacture can be provided.

It is a schematic diagram which shows an example of a composite molded object, (A) is a perspective view, (B) is the PP sectional view taken on the line in (A). It is a schematic explanatory drawing about the manufacturing method of a composite molded object, (A)-(C) is explanatory drawing about an inner layer formation process, (D)-(F) is explanatory drawing about an outer layer formation process. It is a schematic diagram explaining the evaluation method of dimensional accuracy, (A) is a perspective view, (B) is a figure which shows the positional relationship of the both end surfaces seen from the perpendicular line M direction of (A).

  Hereinafter, an embodiment of the present invention will be described in detail. The present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within a range that does not impair the effects of the present invention.

[Composite molded body 100]
In FIG. 1, the schematic diagram of the composite molded object 100 of this embodiment is shown. As shown in FIG. 1, the composite molded body 100 includes an inner layer composed of an inner layer member 1 and an outer layer 2. Note that “the dimensional accuracy is good (excellent, high)” means here that the difference between the size and shape required of the composite molded body and the size and shape of the actually molded composite molded body. It means small. The composite molded body 100 of the present embodiment, which will be described in detail below, is particularly large and flat on the resin injection port side of the outer layer (the resin injection port side of the outer layer forming mold) and on the opposite side (the resin flow end side). It is suppressed that the position shifts, and the dimensional accuracy is superior to the conventional one.

(Inner layer member 1)
The inner layer member 1 is an insert member that constitutes the inner layer of the composite molded body 100. As shown in FIG. 1B, the inner layer member 1 (inner layer) has at least one surface 1a and surface 1b facing opposite to each other. In the following, the “surface” is preferably a flat surface or a substantially flat surface. The “substantially flat surface” means, for example, that the surface may have some unevenness. The shape of the inner layer member 1 can be the same shape as the shape of the composite molded body 100 so as to be the basis of the shape required for the composite molded body 100 to be obtained. For example, the shape having the surfaces 1a and 1b facing the opposite sides may be a columnar shape or a prismatic shape, or a columnar shape having an upper surface and a lower surface formed in a stepped shape. The dimension of the inner layer member 1 is a size obtained by subtracting the thickness of the outer layer 2 described later from the dimension required for the composite molded body 100.

  Although the material of the inner layer member 1 and its manufacturing method are not particularly limited, it is preferable to include a resin composition from the viewpoint of weight reduction and cost. In addition, in order to distinguish from the resin composition (“first resin composition” or “resin composition B”) constituting the outer layer 2 described later, the resin composition constituting the inner layer is referred to as “second composition” or This is referred to as “resin composition A”. Although it does not specifically limit as a 2nd resin composition (resin composition A), It is preferable to contain a thermoplastic resin at the point which can be manufactured by injection molding, and raises the intensity | strength of the composite molding obtained. In this respect, it is preferable to contain a crystalline thermoplastic resin.

  The thermoplastic resin (hereinafter also simply referred to as “resin”) is not particularly limited as long as it can be used for injection molding. For example, polyphenylene sulfide, polypropylene, polyethylene, polyethylene terephthalate, polyamide, ethylene -Vinyl acetate copolymer, polyoxymethylene, polybutylene terephthalate, polyether ether ketone and the like. Among these, polyphenylene sulfide, polyoxymethylene, and polybutylene terephthalate are preferable because they are excellent in heat resistance and chemical resistance. The content of the thermoplastic resin in the resin composition A is preferably 10% by mass or more, more preferably 20% by mass or more, and further preferably 25% by mass or more.

  The resin composition A prevents the inner layer member 1 from being deformed or destroyed by the pressure of the resin used for outer layer molding, suppresses the molding shrinkage rate and linear expansion coefficient of the inner layer member 1 itself, and further in the final use. For the purpose of ensuring the required strength, it is preferable to further contain an inorganic filler.

  The inorganic filler has (a) strength and rigidity that can prevent the inner layer member 1 from being deformed or broken in the formation stage of the outer layer 2, and (a) small molding shrinkage and linear expansion coefficient. There is no particular limitation as long as the dimensional change when taken out from the mold after completion of molding is small and (c) the strength and rigidity required for the finally obtained composite molded body can be achieved.

  Examples of the inorganic filler include glass fiber, carbon fiber, whisker fiber, glass flake, mica, talc and the like. Especially, when the tensile strength and rigidity are calculated | required by a composite molded object, it is preferable that an inorganic filler is a high strength carbon fiber at the point which can raise them suitably. Moreover, when it is calculated | required that it is low cost, it is preferable that an inorganic filler is glass fiber.

  The content of the inorganic filler is not particularly limited, but it is preferably 5% by mass or more and 90% by mass or less in the resin composition A in consideration of the above (a) to (c). % To 80% by mass, more preferably 20% to 75% by mass.

  Other additives may be added to the resin composition A as necessary. Other additives include antioxidants, stabilizers, nucleating agents, plasticizers, lubricants, mold release agents, hydrolysis resistance improvers, fluidity improvers, colorants, flame retardants, flame retardant aids, organic Examples thereof include fillers, metal fillers, elastomers and other resins.

  The method for obtaining the resin composition A is not particularly limited, and the above-described thermoplastic resin and, if necessary, an inorganic filler and other additives are used, for example, using a melt-kneading apparatus such as a single-screw or twin-screw extruder. After being melt kneaded and extruded, the obtained resin composition can be obtained by processing into a desired form such as powder, flakes, pellets and the like.

  When the resin composition A is used, the inner layer member 1 can be formed by injection molding, extrusion molding, compression molding, or the like, and those obtained by cutting, bonding, welding, or the like may be used. Moreover, when using a metal and ceramics, what was formed by casting, sintering, etc., and cut | disconnected similarly to the case where the resin composition A is used can be used. The molding conditions when using the resin composition A can be appropriately set according to the resin used. Since the inner layer member 1 is at least partially covered by the outer layer 2, the inner layer member 1 itself may have some deformation such as sinking or warping. In addition, when the inner layer member 1 is an injection-molded body, it has a trace of the resin inlet of the inner layer forming mold in any part.

(Outer layer 2)
The outer layer 2 is an injection-molded body constituting the outer layer (outer member) of the composite molded body 100, and is formed so as to cover at least a part of the inner layer member 1 (inner layer). The outer layer 2 can also be configured to cover the entire inner layer member 1. Since the outer layer 2 is an injection-molded body, as shown in FIG. 1 (B), it has at least one trace 3 of the resin inlet of the outer layer forming mold on either surface. The outer layer 2 includes at least a surface 2a having the trace 3 of the resin injection port (hereinafter, also referred to as “surface 2a on the resin injection port side” or simply “surface 2a”) and a surface facing the surface 2a. 2b (hereinafter also referred to as “surface 2b on the resin flow end side” or simply “surface 2b”). When a plurality of traces 3 of the resin injection port are formed, there may be a plurality of surfaces 2a and 2b. The surface 2a covers at least part of the surface 1a of the inner layer member 1 (inner layer), and the surface 2b covers at least part of the surface 1b of the inner layer member 1 (inner layer). The surface 2a and the surface 2b preferably cover the entire surface 1a and the surface 1b, respectively.

  Since the outer layer 2 has the above-described configuration, a thick wall composed of the inner layer member 1 (inner layer) and the outer layer 2 in a region where at least the surfaces 2a and 2b and at least one surface connecting the surfaces 2a and 2b exist. The part can be formed. Thus, when a thick part is comprised by the several layer of the inner layer member 1 (inner layer) and the outer layer 2, the outer layer 2 is made around the inner layer member 1 (inner layer) which has been manufactured in advance or separately molded. The composite molded body 100 can be formed by injection molding with a small thickness. In this case, the shrinkage of the resin constituting the outer layer 2 can be suppressed, and as a result, the influence of the shrinkage of the resin is less than that of a single layer (as compared with the case of a single injection molding). Dimensional accuracy can be increased.

  Regarding the thickness of the outer layer 2, “the thickness on the resin injection port side” and “the thickness on the opposite side of the resin injection port side”, and “between the surface 2 a on the resin injection port side and the surface 2 b on the flow end side of the resin This will be described separately in the section “Thickness of the surface in”.

First, among the thicknesses of the outer layer 2, “the thickness on the resin injection port side” and “the thickness on the opposite side of the resin injection port side” (the thickness on the surface 2a side and the thickness on the surface 2b side) are shown in FIG. 1 (B), the distance between the surface 2a of the outer layer 2 and the surface 1a of the inner layer member 1 closest to the surface 2a is a, and the surface 2b on the opposite side of the surface 2a and the inner layer closest to the surface 2b When the distance from the surface 1b of the member 1 is b, a and b are thicknesses that satisfy the following formulas I to III.
1.2 ≦ b / a ≦ 2.0. . . I
0.5 mm ≦ a ≦ 2.0 mm. . . II
0.6 mm ≦ b ≦ 3.0 mm. . . III

  The “surface 1a closest to the surface 2a” is formed at a position closest to the surface 2a in the direction from the resin inlet side toward the resin flow end side when the inner layer member 1 has a plurality of surfaces 1a. It means the surface 1a that has been formed. The same applies to “surface 1b closest to surface 2”. “Distance” is the shortest distance (length) when a line is drawn perpendicularly from the surface 2a (or surface 2b) to the surface 1a (or surface 1b).

  The resin composition B constituting the outer layer 2 is injected from the resin injection port of the outer layer forming mold, and then contacts the surface 1a which is the end surface of the inner layer member 1, and then is divided into the inner layer member. 1, and the flow ends of the resin merge again on the side opposite to the side where the resin injection port is located, thereby forming the outer layer 2 where at least the surface 2 a and the surface 2 b cover the inner layer member 1. At this time, as described later, when a crystalline thermoplastic resin is used as the resin, the difference in the orientation of molecular chains (particularly when the resin composition B contains a fibrous inorganic filler, the fibrous inorganic filler This also affects the difference in the orientation of the outer layer), which causes a difference in contraction rate of the outer layer between the vicinity of the surface 2a and the vicinity of the surface 2b. Theoretically, the resin in the vicinity of the surface 2a usually has a slightly higher shrinkage than the resin in the vicinity of the surface 2b. As a result, the dimension of the portion on the surface 2a side (X in FIG. 1B) is on the surface 2b side. It tends to be slightly smaller than the dimension (Y in FIG. 1B).

  Therefore, the value b / a is set to 1.2 or more and 2.0 or less (formula I), and the thickness b on the opposite side to the resin injection port side is increased, so Side) increase the shrinkage of the resin. As a result, the dimension in the vicinity of the surface 2b is slightly reduced, approaching the dimension on the surface 2a side, achieving balance, and improving the dimensional accuracy. If b / a is less than 1.2, the effect cannot be obtained, and the dimension X on the resin inlet side (surface 2a side) is small due to the difference in the orientation of the molecular chain, and the opposite side (surface 2b). Side) dimension Y remains large. If b / a exceeds 2.0, the thickness on the side opposite to the resin injection port becomes too thick, and sink marks may occur on the surface 2b.

  The thickness of the surface 2a is not less than 0.5 mm and not more than 2.0 mm (formula II) as the value a. When a is less than 0.5 mm, the thickness on the resin injection port side becomes thin, so that pressure loss increases, the entire sink becomes easy to occur, and the accuracy of the dimensions X and Y decreases. There may be a shift in the position in plan view between the portion on the resin injection port side of the obtained composite molded body 100 and the portion on the opposite side of the resin injection port (cylindricity deteriorates).

  The thickness of the surface 2b is 0.6 mm or more and 3.0 mm or less (formula III) as the value of b. When b is less than 0.6 mm, it becomes difficult to fill the resin so as to fill the surface 2b, and since the resin must be injected and filled at a very high pressure, the shape is not stable. Moreover, when the inner layer member 1 has distortion, the distortion may remain in the composite molded body 100, which is not preferable. When b exceeds 3.0 mm, the thickness of the portion forming the outer layer is too thick, which may cause sink marks, which is not preferable.

  As described above, since a and b satisfy I to III, even when the resin composition B contains a crystalline thermoplastic resin, the dimension of the portion on the surface 2a side (X in FIG. 1B) and the surface It is possible to prevent a difference from occurring in the dimension of the portion on the 2b side (Y in FIG. 1B), thereby further improving the dimensional accuracy. Further, the dimensional accuracy can be further improved by reducing the difference (hereinafter also referred to as “cylindricity”) between the position of the surface 2a side portion in plan view and the position of the surface 2b side portion in plan view. . Note that the difference (Y−X) between the dimensions X and Y is an index for determining whether the composite molded body is molded with a uniform thickness between the resin inlet side and the resin flow end side. The difference (cylindricity) between the planar positions of the end surfaces 2a and 2b is an index for determining whether the composite molded body is formed without distortion. Either can be measured by the method described later.

  Next, among the thicknesses of the outer layer 2, the “thickness of the surface between the surface 2a on the resin inlet side and the surface 2b on the flow end side of the resin” is not particularly limited, but is substantially constant in each case. It is preferable. On the other hand, if it is too thick, the amount of sink marks (shrinkage amount in the thickness direction) increases, and there is a possibility that a sufficiently high dimensional accuracy cannot be obtained. Therefore, the thickness is preferably 0.5 mm or more and 3.0 mm or less.

  The outer layer 2 includes a first resin composition (hereinafter also referred to as “resin composition B”). Although it does not specifically limit as a 1st composition (resin composition B), It is preferable to contain a thermoplastic resin at the point which can be manufactured by injection molding, and the point which raises the intensity | strength of the composite molding obtained. Thus, it is preferable to contain a crystalline thermoplastic resin.

  The thermoplastic resin is not particularly limited as long as it can be subjected to injection molding, and the same thermoplastic resin as described in the inner layer member 1 can be used. Among these, when the resin composition A and the resin composition B are heat-sealed, the resin contained in the resin composition B (first resin composition) is excellent because the inner layer member 1 and the outer layer 2 are excellent in integrity. And a resin contained in the resin composition A (second resin composition) are preferably heat-fusible (compatible) combinations.

  In particular, (a) the fusibility at the interface is increased, and the heat fusibility with the inner layer member 1 can be further enhanced, and (a) the molding conditions including the mold temperature are the conditions for inner layer molding. It is preferable that the thermoplastic resin contained in the resin composition B contains the same resin as the resin composition A because substantially the same conditions can be used for the outer layer molding and the outer layer molding conditions. In that respect, the thermoplastic resin contained in the resin composition B is also preferably polyphenylene sulfide, polyoxymethylene, or polybutylene terephthalate. The content of the thermoplastic resin in the resin composition B is preferably 10% by mass or more, more preferably 20% by mass or more, and further preferably 25% by mass or more.

  The resin composition B may not contain a fibrous inorganic filler when the resulting composite molded body is used as a sliding member and wear of the surrounding members becomes a problem. desirable. By not containing the fibrous inorganic filler, the surrounding members are not scraped by the fibrous inorganic filler. Note that “does not contain a fibrous inorganic filler” means that it does not contain a fibrous inorganic filler having a large aspect ratio such as glass fiber or carbon fiber, and does not impair the effects of the present invention. It contains a small amount of fine fiber with a diameter of 1 μm or less, such as a plate shape such as graphite or a spherical inorganic filler such as glass beads or spherical graphite, or Tismo within a range that does not significantly affect the dimensional accuracy. The embodiment is not excluded. Moreover, the resin composition B can also contain the other additive which can be contained in the above-mentioned resin composition A as needed. Other additives can be the same as those described above. The method for obtaining the resin composition B is also the same as the resin composition A described above.

(Composite molded body 100)
The composite molded body 100 has an inner layer and an outer layer 2 made of the inner layer member 1, and at least a part of the wall thickness is 5.0 mm or more. The composite molded body 100 can also be configured such that at least a part of the wall thickness is 8.0 mm or more. The composite molded body 100 is covered with an outer layer in addition to being composed of a plurality of layers of an inner layer and an outer layer, despite having a thick portion having a thickness of 5.0 mm or more. Since the position of the inner layer is adjusted appropriately, the dimensional accuracy is superior to the conventional one.

[Method for Manufacturing Composite Molded Body 100]
FIG. 2 is a schematic explanatory view showing a method for manufacturing the composite molded body 100. In the method of manufacturing the composite molded body 100 of the present embodiment, the first resin composition (resin composition B) is injection molded in the presence of the inner layer member 1 to form the outer layer 2 that covers at least a part of the inner layer member. It has the outer layer formation process (Drawing 2 (D)-(F)) which obtains composite fabrication object 100. When the inner layer and the outer layer 2 are formed continuously, the inner layer forming step (FIG. 2A) in which the second resin composition (resin composition A) is injection-molded to form the inner layer member 1 before the outer layer forming step. ) To (C)). Since the resin compositions A and B, the inner layer member 1 and the outer layer 2 are as described above, description thereof is omitted here. Hereinafter, the inner layer forming step and the outer layer forming step will be described in this order.

(Inner layer forming process)
In the inner layer forming step, first, an inner layer forming mold 10 for forming the inner layer member 1 which is the inner layer of the composite molded body 100 is prepared (FIG. 2A). The configuration of the inner layer forming mold 10 will be described later. Then, the resin composition A is injected and filled into the cavity 12 of the inner layer forming mold 10 from the injection molding machine having the inner layer forming mold 10 attached thereto through the resin inlet 11 of the inner layer forming mold 10 and cooled. Then, the inner layer member 1 is formed (FIG. 2B). Then, the inner layer member 1 is obtained by dividing the inner layer forming mold 10 at the parting line PL1 and taking out the inner layer member 1 (FIG. 2C). The conditions for injection molding can be appropriately selected depending on the resin used.

(Outer layer forming process)
In the outer layer forming step, first, an outer layer forming mold 20 for forming the outer layer 2 is attached to an injection molding machine (FIG. 2D). The configuration of the outer layer forming mold 20 will be described later. At least a part of the inner layer member 1 obtained in the inner layer forming step or the inner layer member 1 separately prepared, preferably the whole, is disposed in the cavity 22 of the outer layer forming mold 20, and the outer layer is formed from the injection molding machine. The resin composition B is injected and filled into the cavity portion 22 of the outer layer forming mold 20 through the resin injection port 21 of the molding die 20 and cooled to form the outer layer 2 integrated with the inner layer member 1 (FIG. 2). (E)). The conditions for injection molding can be appropriately selected depending on the resin used. Thereafter, the outer layer forming mold 20 is divided by the parting line PL2 to take out the molded body on which the outer layer 2 is formed, thereby obtaining a composite molded body 100 in which the inner layer made of the inner layer member 1 and the outer layer 2 are integrated. (FIG. 2 (F)).

In the outer layer forming step, the surface 2a on which the resin injection mark 3 of the outer layer 2 is formed covers at least a part of the surface 1a of the inner layer member 1, and the surface 2b facing the surface 2a is the surface 1b of the inner layer member 1. And the distance between the surface 2a and the surface 1a closest to the surface 2a is a, and the distance between the surface 2b and the surface 1b closest to the surface 2b is b, The outer layer 2 is formed so that b satisfies the following formulas I to III.
1.2 ≦ b / a ≦ 2.0. . . I
0.5 mm ≦ a ≦ 2.0 mm. . . II
0.6 mm ≦ b ≦ 3.0 mm. . . III

  Since the outer layer 2 is formed so that a and b satisfy the above formulas I to III, as described above, the molecules and the planar positions of the portion on the resin inlet side and the portion on the opposite side of the resin inlet side It is possible to obtain the composite molded body 100 with good dimensional accuracy by preventing the difference due to the difference in the orientation of the filler.

(Other processes)
The manufacturing method of the composite molded body of this embodiment further includes a step of insert molding a metal part, a step of cutting the inner layer member and / or the composite molded body, and fitting and / or bonding with other members as necessary. Other steps such as a step of welding and a step of welding with another resin molded body may be included.

  The manufacturing method of the composite molded body 100 of the present embodiment is such that the outer layer 2 is injection-molded around the inner layer member 1 manufactured in advance, or when the inner layer is made of a resin composition, the inner layer forming step In addition, since the composite molded body 100 is formed by a plurality of injection moldings including the outer layer forming step, even when the composite molded body 100 having a thick portion is formed, overall shrinkage can be suppressed and dimensional accuracy can be increased. In addition to this, since the position of the inner layer member 1 in the portion covered with the outer layer 2 is adjusted, there is a difference in the size and planar position of the resin inlet side portion and the opposite side portion of the resin inlet side. Thus, a composite molded body 100 with good dimensional accuracy can be obtained.

  Therefore, the manufacturing method of the composite molded body 100 of the present embodiment can obtain sufficient dimensional accuracy without performing dimensional adjustment by post-processing such as lathe processing of the outer peripheral surface and the end surface. Therefore, it is preferable not to adjust the dimensions of the composite molded body 100 after the outer layer forming step in that the cost for post-processing can be reduced. The presence or absence of dimensional adjustment by post-processing can be confirmed, for example, by the presence or absence of post-processing marks appearing on the composite molded body 100. However, even if a post-processing mark is formed on the composite injection-molded body 100, the composite molded body 100 before the post-processing already has a suitable dimensional accuracy, compared with a case where the dimensional accuracy is insufficient. Thus, the aspect of having a trace of post-processing does not deviate from the technical scope of the present invention.

[Mold for composite molding production]
As shown in FIG. 2D, the mold for producing a composite molded body of the present embodiment has an outer layer forming mold 20 for injection molding the outer layer 2 containing the resin composition B. The mold for producing a composite molded body may further include an inner layer forming mold 10 for injection molding the inner layer member 1 containing the resin composition A, as shown in FIG. Since the resin members A and B, the inner layer member 1 and the outer layer 2 are as described above, description thereof is omitted here. Hereinafter, the inner layer forming mold 10 and the outer layer forming mold 20 will be described in this order.

(Inner layer forming mold 10)
The inner layer forming mold 10 is a mold for forming the inner layer member 1 and, as shown in FIG. 2A, a cavity 12 filled with the resin composition A through the resin injection port 11 from the injection molding machine. Have In the present embodiment, the cavity 12 includes a cavity block 14 and a movable core block 15.

  The dimensions (height and width) of the cavity 12 are determined from the dimensions of the composite molded body 100, the thickness a of the surface on the resin injection port side of the outer layer 2 obtained in the outer layer forming step described later, and the opposite of the resin injection port side. The shrinkage of the resin composition A after subtracting the thickness b on the side (surface on the flow end side of the resin) and the thickness of the surface between the surface on the resin injection port side and the surface on the flow end side of the resin The dimensions are for the rate.

  The inner layer forming mold 10 may have a holding portion 13 for holding the obtained inner layer member 1. When the holding unit 13 is provided, the holding unit 13 is formed integrally with the movable core block 15, so that the inner layer member 1 is formed together with the movable core block 15 while the obtained inner layer member 1 is held by the holding unit 13. It is possible to move from the process to the outer layer forming process. The holding portion 13 is preferably configured to be able to change the position of the inner layer member 1. When the holding part 13 is configured so that the position of the inner layer member 1 can be changed, it can also be used as a holding part 23 in an outer layer forming mold described later, and two-stage injection molding can be performed in a series of flows. it can.

  In the inner layer forming mold 10 of the present embodiment, after the resin composition A is filled from the resin injection port 11, the resin composition A is solidified to form the inner layer member 1, and the cavity block 14 is formed by the parting line PL1. And when the core block 15 is separated, the inner layer member 1 can be taken out.

(Outer layer forming mold 20)
The outer layer forming mold 20 is a mold for forming the outer layer, and as shown in FIG. 2D, from the injection molding machine so as to cover at least a part of the inner layer member 1 containing the resin composition A. It has the cavity part 22 with which the resin composition B is filled through the resin injection port 21 of the outer layer forming mold 20, and the holding part 23 for holding the inner layer member in the cavity part.

  In the present embodiment, the cavity 22 includes a cavity block 24 and a core block 25. The width of the hollow portion 22 (the length in the direction perpendicular to the direction in which the resin injection port 21 extends) is at least part of the thickness (w1 in FIG. 1A) of the obtained composite molded body is 5.0 mm or more. As such, at least a part of the width w2 is 5.0 mm or more. The width w2 can be set to 8.0 mm or more. Further, the height of the hollow portion 22 (the length in the direction in which the resin injection port 21 extends) may be a size that allows for the shrinkage rate of the resin in the dimensions required for the obtained composite molded body 100.

The holding portion 23 has a surface 2a on which the trace 3 of the resin injection hole 3 of the outer layer 2 to be obtained covers at least a part of the surface 1a of the inner layer member 1, and a surface 2b facing the surface 2a opposite to the surface 2a. When the distance between the surface 2a and the surface 1b closest to the surface 2a is a, and the distance between the surface 2b and the surface 1b closest to the surface 2b is b , A and b hold the inner layer member 1 at a position satisfying the following formulas I to III.
1.2 ≦ b / a ≦ 2.0. . . I
0.5 mm ≦ a ≦ 2.0 mm. . . II
0.6 mm ≦ b ≦ 3.0 mm. . . III

  The position of the inner layer member 1 disposed in the cavity portion 22 such that a and b are within the above numerical range is the distance between the surfaces 1a and 1b of the inner layer member 1 and the inner surfaces 20a and 20b of the cavity portion 22. What is necessary is just to make a 'and b' (FIG.2 (D)) into the position which anticipated the shrinkage | contraction rate of resin in the numerical range of a and b. The shrinkage rate of the resin varies depending on the type of resin and the size of the composite molded body 100. For example, in the case of polyphenylene sulfide, a shrinkage of about 0.2% to 0.8% is expected in the resin flow direction. Can do.

  It is preferable that the holding part 23 is configured so that the position of the inner layer member 1 can be changed. For example, by configuring the holding portion 23 to expand and contract up and down, the holding portion 23 can be used as the holding portion 13 that can be provided in the inner layer forming mold 10 as necessary. The position of the inner layer member 1 can be easily adjusted in the cavity 22 so that the values of a and b are within a predetermined range. For example, in FIGS. 2C and 2D, the core block 15 of the inner layer forming mold 10 moves to the outer layer forming mold 20 in a state where the holding portion 13 holds the inner layer member 1. In the outer layer forming mold 20, the holding portion 13 protrudes to a position where the values a and b are in the numerical range to become the holding portion 23, and holds the inner layer member 1 in the cavity portion 22.

  The shape of the holding portions 13 and 23 is not particularly limited, but a resin composition that fills the cavity portion 22 with the outer layer forming mold 20 by removing a part of the inner layer member 1 that is pierced into the inner layer member 1 and providing an undercut. It is possible to prevent the position from being shifted due to the resin pressure of the object B. The length and width of the holding portions 13 and 23 are not particularly limited, and may be appropriately selected according to the size of the obtained composite molded body 100 and the strength required to hold the inner layer member 1 and the composite molded body 100. it can.

  In the present embodiment, the holding portion 23 may be formed integrally with the core block 25. In the outer layer forming mold 20, after the resin composition B is filled from the resin injection port 21, when the resin composition B is hardened and the outer layer 2 is formed, the cavity block 24 and the core block 25 are formed by the parting line PL2. Can be configured to separate. The composite molded body 100 is held by a holding portion 23 provided in the core block 25, and the composite molded body 100 is pulled out by applying a force to the end of the composite molded body 100, thereby forming an inner layer made of the inner layer member 1. And the composite molded object 100 which has the outer layer 2 can be obtained. In the composite molded body 100 obtained in this way, the trace 4 of the holding portion 23 is formed in a hollow shape.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the interpretation of the present invention is not limited by these examples.

[Examples 1 to 5, Comparative Examples 1 to 4]
Using the following resin compositions as the first resin composition (resin composition B) and the second resin composition (resin composition A), a composite molded body having an inner layer member and an outer layer is obtained by the method described later. It was.
First resin composition (resin composition B): “Durafide PPS (registered trademark) 0220A9” manufactured by Polyplastics Co., Ltd., polyphenylene sulfide resin containing no fibrous inorganic filler Second resin composition (resin composition A): 70% by mass of the above resin composition B and 30% by mass of talc (particle diameter D50: 3 μm)

(Inner layer forming process)
A mold for forming an inner layer in which a cavity is formed by a cavity and a core block was prepared. A mold is attached to an injection molding machine (manufactured by FANUC CORPORATION) with a pin with a diameter of 2.5 mm protruding from the core block, and the resin composition A is injected into the cavity of the mold from the nozzle of the injection molding machine. Injection was performed to obtain a cylindrical inner layer member having a diameter of 6 mm and a height of 9 mm. The inner layer member is held by the pin at a depth of 3 mm from the end surface on the flow end side of the resin. The conditions for injection molding are shown below.
Pre-drying: 120 ° C, 6 hours Cylinder temperature: 320 ° C
Mold temperature: 140 ° C
Injection speed: 50mm / sec
Holding pressure: 50 MPa (500 kg / cm ² )

(Outer layer forming process)
A mold for forming an outer layer in which a cavity portion is formed by a cavity block and a core block was prepared. The inner layer member was moved into the cavity of the outer layer forming mold while being held by the pins of the core block. Adjust the height so that the pin holding the inner layer member protrudes further, and adjust the protruding height so that the thickness of the outer layer (a and b below) is the value shown in Table 1. Thus, the inner layer member was placed in the cavity of the mold.
a: Distance (mm) between the surface having the trace of the resin inlet of the outer layer and the surface (upper surface) of the inner layer member adjacent to the surface
b: Distance (mm) between the surface of the outer layer opposite to the surface having the trace of the resin inlet and the surface (lower surface) of the inner layer member 1 adjacent to the surface.

  Next, the resin composition B is injected from the nozzle of an injection molding machine into the cavity of the mold, an outer layer is formed so as to cover the periphery of the inner layer member, and after cooling, the composite molded body is taken out from the mold and pulled out from the pin. Thus, a cylindrical composite molded body having a diameter of 10 mm and a height of 13 mm in which the inner layer member and the outer layer shown in FIG. 1 were integrated was obtained. The injection molding conditions were the same as the inner layer molding process. This composite molded body has a diameter of 10 mm and can be said to be thick. In addition, since the inner layer member exists in the inner layer of the composite molded body, when attention is paid only to the outer layer, the shape is a cylindrical shape. Moreover, the hollow which is the trace of the pin which hold | maintained the inner layer member was formed in the end surface by the side of the flow end of resin of a composite molded object.

[Evaluation]
(Thickness on the resin inlet side and on the opposite side)
About the composite molded bodies obtained in the examples and comparative examples, cut along the PP line shown in FIG. 1, and from the surface 2a on the resin inlet side of the outer layer and the surface 2b on the opposite side, the surface of the inner layer member respectively. Among them, the distances a and b from the resin injection port side to the closest surface in the direction from the resin flow end side were measured. The results are shown in Table 1.

(Dimensions X and Y of composite molded body)
A method for measuring the dimensions X and Y of the composite molded body will be described with reference to FIGS. For the composite molded bodies obtained in the examples and comparative examples, the minimum circumscribed circles 200a and 200b at the distances a and b measured as described above are created, the diameters X and Y are measured, and the difference Y-X is obtained. Calculated. The results are shown in Table 1.
When the value of YX is negative, it means that the composite molded body is thicker on the resin injection port side than on the opposite side. On the other hand, when the value of Y−X is positive, it means that the portion on the side opposite to the resin injection port side is thicker than the portion on the resin injection port side. Therefore, it can be evaluated that a composite molded body having a uniform thickness is obtained as the value of Y-X is closer to 0.

(Cylindricity)
With reference to FIG. 3, the measuring method of cylindricity is demonstrated. Here, the cylindricity is obtained by calculating the maximum value of the deviation (difference) t when the minimum circumscribed circles 200a and 200b are viewed from the vertical line M direction. The smaller the value of t, the smaller the deviation between the plane position of the portion of the composite molded body on the resin injection side and the plane position of the portion opposite to the resin injection port, and the higher the dimensional accuracy. Can be evaluated. On the other hand, as the value of t is larger, the plane position of the resin injection row side portion of the composite molded body is shifted from the plane position of the opposite side portion of the resin injection port, and it is evaluated that the dimensional accuracy is lower. it can.

  As is apparent from Table 1, the composite molded bodies of Examples 1 to 5 have a small Y-X value and a small cylindricity value despite having a thick portion of 5.0 mm or more and excellent dimensional accuracy. It was.

1 Inner layer member (inner layer)
2 Outer layer 3 Trace of resin injection port 4 Trace of holding part 10 Inner layer forming mold 20 Outer layer forming mold 11, 21 Resin injection port 12, 22 Cavity part 13, 23 Holding part 14, 24 Cavity block 15, 25 Core Block PL1, PL2 Parting line 100 Composite molded body A Resin composition A
B Resin composition B

Claims (11)

In the presence of the inner layer member, the first resin composition is injection-molded to form an outer layer that covers at least a part of the inner layer member, and an outer layer is formed to obtain a composite molded body having the inner layer made of the inner layer member and the outer layer. Having a process,
The thickness of at least a part of the composite molded body is 5.0 mm or more,
The inner layer member has at least one surface 1a and surface 1b facing opposite sides,
In the outer layer forming step, the surface 2a on which the trace of the resin injection port of the outer layer is formed covers at least a part of the surface 1a, and the surface 2b facing the surface 2a covers at least a part of the surface 1b. When the distance between the surface 2a covering and the surface 1a closest to the surface 2a is a and the distance between the surface 2b and the surface 1b closest to the surface 2b is b, a and b However, an outer layer is formed so that the following formulas I-III may be satisfied, The manufacturing method of the composite molded object characterized by the above-mentioned.
1.2 ≦ b / a ≦ 2.0. . . I
0.5 mm ≦ a ≦ 2.0 mm. . . II
0.6 mm ≦ b ≦ 3.0 mm. . . III   The manufacturing method of the composite molded object of Claim 1 which does not adjust the dimension of the said composite molded object after the said outer layer formation process.   The method for producing a composite molded body according to claim 1 or 2, further comprising an inner layer forming step of forming the inner layer member by injection molding a second resin composition before the outer layer forming step.   The method for producing a composite molded body according to claim 3, wherein the first resin composition and the second resin composition have heat-fusibility.   The method for producing a composite molded article according to claim 3 or 4, wherein the first resin composition and the second resin composition contain a crystalline thermoplastic resin.   The production of the composite molded article according to any one of claims 3 to 5, wherein the second resin composition contains an inorganic filler, and the first resin composition does not contain a fibrous inorganic filler. Method. A composite molded body having an inner layer and an outer layer covering at least a part of the inner layer and containing the first resin composition,
At least a portion of the wall thickness is 5.0 mm or more,
The inner layer has at least one surface 1a and surface 1b facing away from each other;
The outer layer has a surface 2a having a trace of a resin injection port and a surface 2b facing the surface 2a,
The surface 2a covers at least a part of the surface 1a, the surface 2b covers at least a part of the surface 1b, and the distance between the surface 2a and the surface 1a closest to the surface 2a is a, A composite molded body, wherein a and b satisfy the following formulas I to III, where b is the distance between the surface 2b and the surface 1b closest to the surface 2b.
1.2 ≦ b / a ≦ 2.0. . . I
0.5 mm ≦ a ≦ 2.0 mm. . . II
0.6 mm ≦ b ≦ 3.0 mm. . . III   The composite molded body according to claim 7, wherein the inner layer includes a second resin composition. A mold for producing a composite molded body,
In the presence of the inner layer member, it has an outer layer forming mold for injection molding the first resin composition to form an outer layer covering at least a part of the inner layer member,
The outer layer forming mold has a hollow portion filled with the first resin composition through a resin injection port, and a holding portion for holding the inner layer member in the hollow portion,
The width of at least a part of the hollow portion is 5.0 mm or more,
The inner layer member has at least one surface 1a and surface 1b facing opposite sides,
In the holding portion, the surface 2a on which the trace of the resin inlet of the outer layer to be obtained is formed covers at least a part of the surface 1a, and the surface 2b facing the surface 2a is at least a part of the surface 1b. The distance between the surface 2a and the surface 1a closest to the surface 2a is a, and the distance between the surface 2b and the surface 1b closest to the surface 2b is b. , A and b hold the inner layer member at a position satisfying the following formulas I to III: a mold for producing a composite molded body.
1.2 ≦ b / a ≦ 2.0. . . I
0.5 mm ≦ a ≦ 2.0 mm. . . II
0.6 mm ≦ b ≦ 3.0 mm. . . III   The mold for manufacturing a composite molded body according to claim 9, wherein the holding portion is configured to be able to change a position of the inner layer member.   The mold for producing a composite molded body according to claim 9 or 10, comprising an inner layer forming mold for injection molding the second resin composition to form the inner layer member.

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