Method of manufacturing resin molded body

Abstract

To provide a method of manufacturing a resin molded body in which generation of void is suppressed.SOLUTION: A method of manufacturing a resin molded body having a thick wall portion and a thin wall portion has: a preparation step of preparing an insert member 100 having a base portion 11 and a protrusion 12; a filling step of inserting and fixing the insert member 100 in a mold 200, and filling a molten thermoplastic resin R into an internal space S of the mold using an injection molding apparatus; and a pressure holding step of applying a holding pressure to the thermoplastic resin filled in the internal space. In the pressure holding step, cooling of a first portion to be the thick wall portion in the internal space is accelerated, and cooling of a second portion to be the thin wall portion in the internal space is suppressed.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a method for producing a resin molded article. [Background technology]

[0002] It is known that resin molded bodies are manufactured by injection molding. Injection molding usually involves a filling step of filling a space (cavity) in a mold with molten resin, and a pressure holding step of applying a holding pressure to the resin filled in the space. For example, Patent Document 1 discloses a method for manufacturing an electric fusion pipe joint in which a thermoplastic resin is injection molded into a cavity in a mold to obtain a joint body, the method including a process of providing a pressurizing means outside the cavity adjacent to a void generated in the molded body by a gas such as air enclosed in the joint body, and partially pressurizing the joint body using the pressurizing means from after injection molding until cooling and solidifying to eliminate the void. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-034719 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, when a resin molded body having a thick part and a thin part is manufactured by injection molding, it is assumed that a mold with an inlet provided on the side that will become the thin part of the resin molded body is used, and the resin introduced from the inlet toward the side that will become the thick part is flowed in the internal space of the mold. It is also assumed that the temperature of the resin is less likely to decrease in the part that will become the thick part in the internal space of the mold than in the part that will become the thin part. In that case, the resin in the part that will become the thin part solidifies first, and pressure is not applied to the resin in the part that will become the thick part during the pressure holding process, which may cause voids to occur.

[0005] The present disclosure has been made in consideration of the above-mentioned circumstances, and has as its main object to provide a method for producing a resin molded article in which the occurrence of voids is suppressed. [Means for solving the problem]

[0006] [1] A method for manufacturing a resin molded body having a thick portion and a thin portion, the method comprising: a preparation step of preparing an insert member having a base and a convex portion; a filling step of inserting and fixing the insert member into a mold and using an injection molding device to fill molten thermoplastic resin into the internal space of the mold; and a pressure holding step of applying a holding pressure to the thermoplastic resin filled in the internal space, wherein in the pressure holding step, cooling of a first portion in the internal space that will become the thick portion is promoted and cooling of a second portion in the internal space that will become the thin portion is suppressed.

[0007] [2] The method for producing a resin molded product according to [1], further comprising the step of promoting cooling of the first portion using a cooling gas or a cooling liquid.

[0008] [3] The method for producing a resin molded body according to [1] or [2], wherein the mold has a heat insulating material, and the heat insulating material suppresses cooling of the second portion.

[0009] [4] The method for manufacturing a resin molded body described in any of [1] to [3], wherein the insert member has a laminate structure having a laminate portion having a plurality of electrodes stacked in the thickness direction and a seal portion covering the outer edge of the laminate portion, and a plurality of voltage terminals protruding from the inside to the outside of the laminate in a first direction perpendicular to the thickness direction, and a housing that accommodates the tip portions of the plurality of protruding voltage terminals, and has a gap between the laminate and the housing in the first direction. Effect of the Invention

[0010] The present disclosure has an effect of making it possible to manufacture a resin molded article in which the occurrence of voids is suppressed. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic diagram illustrating an insert member prepared in a preparation step in the present disclosure. [Diagram 2] 1A to 1C are diagrams illustrating a filling step and a pressure holding step in the present disclosure. [Diagram 3] 1 is a cross-sectional view illustrating a laminated structure according to the present disclosure. [Figure 4] FIG. 2 is a schematic perspective view illustrating a voltage terminal in the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The manufacturing method of the resin molded body in the present disclosure will be described in detail below. Each of the figures shown below is a schematic illustration, and the size and shape of each part are appropriately exaggerated to facilitate understanding. In addition, in this specification, when expressing an aspect in which another member is arranged relative to a certain member, the term "above" or "below" includes both a case in which another member is arranged directly above or below a certain member so as to be in contact with the certain member, and a case in which another member is arranged above or below a certain member via another member, unless otherwise specified. Here, in the present disclosure, the "thick part" refers to a part whose length in the first direction described later is longer than the thin part. In other words, the "thin part" refers to a part whose length in the first direction described later is shorter than the thick part.

[0013] FIG. 1 is a schematic diagram illustrating an insert member in the present disclosure. Specifically, FIG. 1(a) is an exploded view illustrating an example of an insert member, FIG. 1(b) is a schematic plan view illustrating an example of an insert member, and FIG. 1(c) is a partial cross-sectional view illustrating an example of an insert member. FIG. 2 is a diagram illustrating a filling step and a pressure holding step in the present disclosure, and FIGS. 2(a) and 2(b) are schematic cross-sectional views illustrating the filling step, and FIG. 2(c) is a schematic cross-sectional view illustrating the pressure holding step. Specifically, FIG. 1(c) and FIG. 2(b) are cross-sectional views of a through-hole portion of a housing when the insert member has a housing.

[0014] In the manufacturing method of the resin molded body in the present disclosure, first, as shown in Figs. 1(a) and (b), an insert member 100 having a base portion 100a and a protruding portion 100b is prepared (preparation step). Next, as shown in Figs. 2(a) and (b), the insert member 100 is inserted and fixed in a mold 200, and an injection molding device (not shown) is used to fill the internal space S of the mold 200 with molten thermoplastic resin R (filling step). Then, as shown in Fig. 2(c), a holding pressure is applied to the thermoplastic resin R filled in the internal space S (pressure holding step). Furthermore, in the present disclosure, in the pressure holding step, cooling of the first portion that will be the thick portion in the internal space S is promoted, and cooling of the second portion that will be the thin portion in the internal space S is suppressed. Here, as shown in Fig. 2(b), the first portion that will be the thick portion refers to a portion of the internal space of the mold 200 where the base portion (laminated body 11) and the protruding portion (voltage terminal 12 and housing 20) of the insert member 100 overlap in the first direction. On the other hand, the second portion that becomes the thin portion refers to a portion of the internal space of the mold 200 where the base of the insert member does not overlap with the protrusion in the first direction.

[0015] In the present disclosure, in the pressure holding step, the cooling of the first portion that will be the thick portion in the internal space S is promoted, and the cooling of the second portion that will be the thin portion in the internal space is suppressed. Therefore, it is possible to promote the solidification of the thermoplastic resin in the portion (first portion) that will be the thick portion where the temperature is difficult to decrease, and to suppress the solidification of the thermoplastic resin in the portion (second portion) that will be the thin portion where the temperature is easy to decrease. Here, as shown in FIG. 2(a), the second portion includes a flow path through which the thermoplastic resin introduced from the inlet H flows to the first portion. In addition, pressure is applied through the flow path in the pressure holding step. Therefore, by suppressing the solidification of the second portion, it is possible to suppress the blocking of the flow path before the first portion solidifies, and it is possible to apply sufficient pressure to the first portion in the pressure holding step. Therefore, in the manufacturing method of the resin molded body in the present disclosure, it is possible to manufacture a resin molded body in which the generation of voids is suppressed, particularly in the thick portion.

[0016] In injection molding, the molding cycle (cycle time), which is the unit time required to manufacture one molded product, is used as an index of the production efficiency of the molded product. The molding cycle is the total time of the time to open the mold, the time to fill the resin, the time to hold the pressure, the time to cool the filled resin, the time to open the mold, and the time to remove the molded product. In this regard, the method for manufacturing a resin molded product in the present disclosure has the advantage that the cooling time can be shortened and the molding cycle can be shortened because the cooling of the thick-walled portion, where the temperature of the resin is difficult to decrease, is promoted.

[0017] 1.Preparation process The preparing step in the present disclosure is a step of preparing an insert member having a base portion and a protrusion portion.

[0018] An example of the insert member will be described with reference to Figures 1, 3, and 4. Figure 1 is as described above. Figures 3 and 4 are diagrams illustrating members constituting the insert member shown in Figure 1. Specifically, Figure 3 is a schematic cross-sectional view illustrating a laminated structure in the insert member shown in Figure 1, and Figure 4 is a schematic perspective view illustrating a voltage terminal in the insert member shown in Figure 1.

[0019] 1(a) and (b) includes a laminated structure 10 having a laminate 11 and a plurality of voltage terminals 12 protruding from the inside to the outside of the laminate 11 in a first direction x perpendicular to the thickness direction z, and a housing 20 that accommodates tip portions of the protruding voltage terminals 12. As shown in FIG. 1(b), there is a gap between the housing 20 and the laminate 11 in the first direction x. As shown in FIG. 1(b), the laminate 11 is a base 100a of the insert member 100, and the voltage terminals 12 and the housing 20 protruding from the laminate 11 are a protruding portion 100b of the insert member 100.

[0020] 3, the laminated structure 10 has a laminated body 11 having a laminated portion 11a having a plurality of electrodes E laminated in a thickness direction z and a sealing portion 11b covering the outer edge of the laminated portion 11a. The laminated structure 10 also has a voltage terminal 12 protruding from the inside to the outside of the laminated body 11 in a first direction x perpendicular to the thickness direction z. The sealing portion 11b is usually disposed along the entire outer edge of the laminated portion 11a.

[0021] The laminated portion 11a of the laminated structure 10 shown in FIG. 3 has a bipolar electrode BP, a positive electrode end electrode CA, and a negative electrode end electrode AN as electrodes E. The electrode E has a current collector 1 and an active material layer (at least one of a positive electrode active material layer 2 and a negative electrode active material layer 3). As shown in FIG. 2, the bipolar electrode BP has a current collector 1, a positive electrode active material layer 2 arranged on one main surface of the current collector 1, and a negative electrode active material layer 3 arranged on the other main surface of the current collector 1. The positive electrode end electrode CA has a current collector 1 and a positive electrode active material layer 2 arranged on one main surface of the current collector 1. The negative electrode end electrode AN has a current collector 1 and a negative electrode active material layer 3 arranged on one main surface of the current collector 1.

[0022] As shown in FIG. 3, the laminated portion 11a may have a plurality of power generation units U (U1, U2, U3) laminated in the thickness direction z. A power generation unit is usually a unit having a positive electrode active material layer, a separator, and a negative electrode active material layer. When an electrolyte is supplied to the power generation unit, the laminate functions as a battery. As shown in FIG. 3, the power generation units U (U1, U2, U3) may be connected in series with each other. Although not particularly shown, the power generation units may also be connected in parallel with each other.

[0023] As shown in FIG. 4, the voltage terminal 12 has a connection portion 12a, an intermediate portion 12b, and an insertion portion 12c. Usually, one voltage terminal is provided for one power generating unit in the above-mentioned laminate. The connection portion 12a is a portion located inside the above-mentioned laminate, and is connected to the current collector 1 in the power generating unit U as shown in FIG. 3. The insertion portion 12c is a portion located outside the laminate, and is a portion that constitutes the tip portion of the voltage terminal protruding from the laminate. As described later, at least a part of the insertion portion 12c is accommodated in a housing. Also, the intermediate portion 12b is a portion that connects the connection portion 12a and the insertion portion 12c. Usually, a part of the intermediate portion is located outside the laminate in the first direction. That is, one end of the intermediate portion in the first direction (a contact point with the connection portion) may be located inside the laminate, and the other end (a contact point with the insertion portion) may be located outside the laminate. As shown in FIG. 4, the width of connection portion 12a of voltage terminal 12 (the length in second direction y perpendicular to first direction x) is usually wider than the widths of intermediate portion 12b and insertion portion 12c.

[0024] As shown in FIG. 1(c), the entirety of the insertion portion 12c may be inserted into the housing 20 (through hole) in the first direction x. On the other hand, although not shown, a part of the insertion portion may be inserted into the housing. Also, a part of the intermediate portion may be inserted into the housing in the first direction. On the other hand, the intermediate portion may not be inserted into the through hole. By inserting a part of the intermediate portion into the through hole or not inserting the intermediate portion into the through hole, a gap can be provided between the laminate and the housing in the first direction.

[0025] As shown in FIG. 1(a), the housing 20 has a plurality of through holes 21. The number of the through holes is equal to the number of the voltage terminals. As shown in FIG. 1(c), the through hole 21 has a first opening 21a located on the laminate 11 side and a second opening 21b located on the opposite side to the first opening 21a in the first direction x. As shown in FIG. 1(c), the through hole has an intermediate region 21c that is narrower than the first opening 21a and the second opening 21b. The intermediate region 21c can prevent the thermoplastic resin filled in the filling step described later from leaking from the second opening 21b.

[0026] 2.Filling process 2(a), in the filling step of the present disclosure, the insert member 100 is inserted into and fixed in a mold 200, and an injection molding device (not shown) is used to fill molten thermoplastic resin into the internal space S of the mold 200. As shown in FIG. 2(a), the protruding portion (voltage terminal and housing) side of the insert member is inserted into the mold and fixed.

[0027] Also, the mold is usually formed with an inlet for introducing the thermoplastic resin into the internal space. As shown in FIG. 2(a), the through hole H is usually formed at a position that does not overlap with the convex portion (voltage terminal and housing) of the insert member in the second direction y. In FIG. 2(a), the inlet H is formed on the front side of the paper in the thickness direction z, and the thermoplastic resin introduced from the inlet H spreads in the second direction y to fill the internal space S. Here, the internal space is a continuous space, and as shown in FIG. 2(b), the through hole 21 of the housing 20 can also be regarded as the internal space of the mold 200. Therefore, as shown in FIG. 2(b), the thermoplastic resin R is also filled into the through hole 21 of the housing 20.

[0028] Examples of the thermoplastic resin to be filled include polyolefins such as polyethylene (PE) and polypropylene (PP). Examples of polyethylene include high density polyethylene (HDPE). The density of high density polyethylene is, for example, 0.94 g / cm. 3More than 0.973g / cm 3 On the other hand, other examples of thermoplastic resins include polyvinyl chloride (PVC), polystyrene (PS), acrylonitrile-butadiene-styrene (ABS), acrylonitrile-styrene (AS), polymethyl methacrylate (PMMA), polybutylene terephthalate (PBT), and polyethylene terephthalate (PET).

[0029] The injection molding device is not particularly limited, and may be, for example, a conventionally known device having a nozzle, a cylinder connected to the nozzle, a screw movable in the internal space of the cylinder, and a hopper for supplying raw material to the cylinder. The screw may have a main body, a head, and a check ring disposed between the main body and the tip. The thermoplastic resin fed into the hopper falls into the heated cylinder, and is compressed and kneaded by the rotation of the screw and sent to the nozzle side, and the thermoplastic resin is introduced into the internal space of the mold from the nozzle connected to the inlet of the mold.

[0030] In the filling step, it is preferable to continue filling until the filling amount reaches, for example, 0.85 to 0.95 of the intended filling amount of the thermoplastic resin.

[0031] 3.Pressure holding process The pressure-holding process in the present disclosure is a process of applying a holding pressure to the thermoplastic resin filled in the internal space, and promotes cooling of a first portion that is a thick portion in the internal space and suppresses cooling of a second portion that is a thin portion in the internal space.

[0032] By applying a holding pressure, the remaining thermoplastic resin can be filled and backflow of the thermoplastic resin can be suppressed. The holding pressure is not particularly limited, and is, for example, 0.5 MPa or more and 2.5 MPa or less.

[0033] As a method for promoting the cooling of the first portion, for example, a method of cooling the first portion using a cooling gas or a cooling liquid can be mentioned. As shown in Fig. 2(c), the cooling of the first portion can be promoted by supplying a cooling liquid (or a cooling gas) to the housing and directly cooling the housing. The first portion is as described above.

[0034] The cooling gas may include, for example, cold air and a refrigerant gas. The refrigerant gas may include, for example, a chlorofluorocarbon (CFC). The cooling liquid may include, for example, cold water and a refrigerant liquid. The refrigerant liquid may include, for example, ethylene glycol.

[0035] The cooling conditions can be appropriately adjusted taking into consideration the solidification point of the thermoplastic resin used.

[0036] As a method for suppressing the cooling of the second portion, for example, a method using a heat insulating material can be mentioned. As shown in FIG. 2(c), by using a mold 200 having a heat insulating material 201, the effect of cooling the first portion can be prevented from reaching the second portion. The second portion is as described above.

[0037] 2(c), the size of the heat insulating material 201 is preferably larger than the housing in the first direction x. The size of the heat insulating material 201 is also preferably larger than the housing in the thickness direction z. The material of the heat insulating material is not particularly limited, but examples thereof include resins having high heat resistance, such as polyether ether ketone (PEEK), polyamide, polyphenylene sulfide (PPS), and polyimide.

[0038] 4. Resin molding The resin molded body in the present disclosure typically functions as a member constituting a side surface of a battery module, more specifically, in the battery module, functions as a member constituting a side surface that is connected to an external device, such as a connector of a voltage measuring device.

[0039] The battery module is typically a lithium-ion secondary battery. Examples of uses of the battery module include power sources for vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), electric vehicles (BEVs), gasoline-powered automobiles, and diesel-powered automobiles. In particular, it is preferable to use the battery module as a driving power source for hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), or electric vehicles (BEVs). The power storage module may also be used as a power source for moving objects other than vehicles (for example, railways, ships, and aircraft), and may also be used as a power source for electrical appliances such as information processing devices.

[0040] The present disclosure is not limited to the above-described embodiment. The above-described embodiment is merely an example, and any configuration that is substantially the same as the technical idea described in the claims of the present disclosure and that exhibits similar effects is included in the technical scope of the present disclosure. [Explanation of symbols]

[0041] 1...Current collector 2...Cathode active material layer 3...Negative electrode active material layer 4...Separator 10. Laminated structure 11 ...Laminate 11a …Laminated section 11b ... Seal part 12 ... Voltage terminal 20. Housing 100 ... Insert material 200...Mold 201 ... Insulation material

Claims

1. A method for producing a resin molded product having a thick portion and a thin portion, comprising the steps of: A preparation step of preparing an insert member having a base portion and a protrusion portion; a filling step of inserting and fixing the insert member into a mold and filling an internal space of the mold with a molten thermoplastic resin using an injection molding device; A pressure holding step of applying a holding pressure to the thermoplastic resin filled in the internal space, A method for manufacturing a resin molded body, wherein, in the pressure holding process, cooling of a first portion that becomes the thick portion in the internal space is promoted and cooling of a second portion that becomes the thin portion in the internal space is suppressed.

2. The method for producing a resin molded article according to claim 1 , further comprising the step of: promoting cooling of the first portion by using a cooling gas or a cooling liquid.

3. The mold has a thermal insulation material, The method for producing a resin molded article according to claim 1 , wherein the heat insulating material suppresses cooling of the second portion.

4. The insert member is a laminated structure including: a laminated body having a laminated portion having a plurality of electrodes laminated in a thickness direction and a seal portion covering an outer edge of the laminated portion; and a plurality of voltage terminals protruding from an inside to an outside of the laminated body in a first direction perpendicular to the thickness direction; a housing that accommodates the tip portions of the plurality of protruding voltage terminals; and The method for producing a resin molded article according to claim 1 , wherein a gap is provided between the laminate and the housing in the first direction.

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