JP4233005B2 - In-mold coating method - Google Patents

In-mold coating method Download PDF

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Publication number
JP4233005B2
JP4233005B2 JP2000289228A JP2000289228A JP4233005B2 JP 4233005 B2 JP4233005 B2 JP 4233005B2 JP 2000289228 A JP2000289228 A JP 2000289228A JP 2000289228 A JP2000289228 A JP 2000289228A JP 4233005 B2 JP4233005 B2 JP 4233005B2
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Prior art keywords
mold
resin
cavity
film
injection
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JP2002096352A (en
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実基彦 木村
文人 上羽
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Honda Motor Co Ltd
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Honda Motor Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/16—Making multilayered or multicoloured articles
    • B29C45/1679—Making multilayered or multicoloured articles applying surface layers onto injection-moulded substrates inside the mould cavity, e.g. in-mould coating [IMC]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/17—Component parts, details or accessories; Auxiliary operations
    • B29C45/72—Heating or cooling
    • B29C45/73—Heating or cooling of the mould
    • B29C2045/7343—Heating or cooling of the mould heating or cooling different mould parts at different temperatures

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)
  • Injection Moulding Of Plastics Or The Like (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は、熱可塑性樹脂から成る射出成形品の表面に射出成形工程中に皮膜を形成するインモールドコート方法に関する。
【０００２】
【従来の技術】
従来、特開平７−１１２４５０号公報により、熱可塑性樹脂をキャビティ内に射出充填した後に型締めを行ったまま、熱可塑性樹脂の表面とキャビティ内表面との間に隙間を生じさせ、この隙間に皮膜原料を注入して、射出成形工程中に皮膜形成を行うインモールドコート方法が知られている。このものの第１の態様では、金型のキャビティ内に充填された樹脂が冷却して凝固する際の体積減少で樹脂表面とキャビティ内表面との間に生ずる隙間に皮膜原料を注入している。しかし、かかる隙間がキャビティ内表面に対して樹脂表面のいずれの側、即ち、キャビティを形成する可動型と固定型のいずれの側に生じるか確実でなく、又、皮膜形成が必要な側の樹脂表面は、凝固による収縮の際に不均一な収縮に起因する局所的な窪み（ひけ）が生じて凸凹状に形成されることがあり、このような表面上に皮膜原料を被覆して形成される皮膜の形状精度に問題がある。このため、第２の態様では、金型の可動型に可動式のコア部を設け、樹脂の凝固の際に、金型を閉じたままこのコア部のみを後退させて、樹脂の可動型側の表面とコア部との間に機械的に隙間を生じさせ、この隙間に皮膜原料を注入している。さらに、第３の態様では、金型を構成する固定型と可動型とを入子構造に構成すると共に、樹脂の凝固の際に樹脂が可動型側に固着するようなキャビティ構造を採用して、可動型を少許後退させることにより樹脂の固定型側の表面と固定型のキャビティ内表面との間に機械的に隙間を生じさせ、この隙間に皮膜原料を注入している。
【０００３】
【発明が解決しようとする課題】
上記方法では、樹脂表面に対して隙間が生じる位置が不確実な第１の態様を改善するため、第２の態様では金型の可動型に可動式のコア部を設け、又、第３の態様では金型を構成する固定型と可動型とを入子構造で係合するようにしているが、両態様とも金型の構造が複雑でコストアップの要因となる。
【０００４】
本発明は、上記問題点に鑑み、簡易な構造の金型を用いて、熱可塑性樹脂の射出成形工程中に、射出成形品の皮膜形成を行うべき表面に精度良く皮膜を形成し得るようにしたインモールドコート方法を提供することを課題としている。
【０００５】
【課題を解決するための手段】
上記課題を解決するため、本発明は、金型のキャビティ内の熱可塑性樹脂から成る射出成形品の表面に皮膜を形成するインモールドコート方法において、金型を型締めした状態で金型のキャビティ内に熱可塑性樹脂を射出充填した後、金型を型締めしたまま金型を構成する１対の型のうち射出成形品の皮膜を形成すべき表面側に位置する一方の型よりも他方の型を低温に保った状態で、前記樹脂の該他方の型側を凝固させ、次に、前記一方の型の温度を低下させて前記樹脂の該一方の型側を凝固させ、その後、該樹脂の前記一方の型側の表面と該一方の型のキャビティ内表面との間に皮膜原料を注入している。
【０００６】
本発明により、前記樹脂の他方の型側を凝固させると、凝固に伴う樹脂収縮により該樹脂の他方の型側の表面と他方の型のキャビティ内表面との間に隙間が生じ、次に、前記樹脂の一方の型側を凝固させると、一方の型側に位置する皮膜形成が必要な樹脂表面が一方の型のキャビティ内表面の形状を転写して形成され、又、前記樹脂の一方の型側の表面と一方の型のキャビティ内表面との間の粘着状態が解消される。このため、前記樹脂の一方の型側の凝固が完了すると、一方の型のキャビティ内表面の形状が転写された前記樹脂表面が、僅かな外力の作用により一方の型のキャビティ内表面から剥離できるようになり、又、上記のように前記樹脂の他方の型側の表面と他方の型のキャビティ内表面との間に隙間が生じていて前記樹脂が他方の型側で支持されていないため、前記樹脂が一方の型から離型し易い状態になる。したがって、その後に前記樹脂の一方の型側の表面と一方の型のキャビティ内表面との間に皮膜原料を注入でき、このようにすることにより、射出成形品の表面に精度良く皮膜を形成できる。
【０００７】
この場合、前記皮膜原料の注入前に、前記樹脂の前記一方の型側の表面と該一方の型のキャビティ内表面との間に圧縮ガスを供給すれば、上記のように一方の型のキャビティ内表面の形状を転写して形成された前記樹脂表面を維持したまま前記樹脂が一方の型から離型して、前記樹脂表面と一方の型のキャビティ内表面との間に隙間を生じ、その後の皮膜原料の注入が容易になる。
【０００８】
【発明の実施の形態】
図１（ａ）〜（ｄ）は、立て形射出成形機を用いたインモールドコート工程を示す。図１を参照して１は、立て形射出成形機の金型の要部を示し、金型１は可動型たる上型１ａと固定型たる下型１ｂとから成り、上型１ａを下型１ｂに対し型締めすることにより上型１ａと下型１ｂとの間に所要の製品形状のキャビティ２が形成されるように構成されている。又、下型１ｂのキャビティ内表面２ｂの略中央に樹脂供給路３に連なる樹脂供給口３ｂを設け、図外の射出機より熱可塑性樹脂４から成る溶融樹脂が樹脂供給路３を経てキャビティ２内に射出されるように構成され、さらに、上型１ａのキャビティ内表面２ａの部分に注入路５に連なる注入口５ａを設けると共に、注入路５に図外のコンプレッサと図外の注入機とのいずれか一方を選択可能に接続できるようにして、注入路５及び注入口５ａ経由で、コンプレッサ内の圧縮空気や窒素ガス等の圧縮ガスと皮膜原料注入機内の皮膜原料６とをキャビティ２内に選択的に注入するように構成されている。
【０００９】
射出成形に際しては、先ず、図１（ａ）に示すように、金型１の上型１ａと下型１ｂとを当接させて閉じると共に射出充填時の射出圧力に抗し得るように金型１を図外の型締め装置で型締めし、この状態で、図外の射出機から溶融状態の熱可塑性樹脂４を供給路３の樹脂供給口３ｂを経て金型１のキャビティ２内に射出充填する。そして、キャビティ２が樹脂で満たされたところで樹脂供給路３を適宜の遮断手段により遮断して射出充填工程を完了する。尚、注入口５ａは、後述の圧縮ガスや皮膜原料の注入を行うまで適宜の閉塞手段により閉塞されている。
【００１０】
次に、金型１を型締めしたまま、上型１ａ及び下型１ｂの金型温度を低下させるが、この際、図１（ｂ）に示すように、上型１ａは上記の射出充填工程時の金型温度を保った状態で、下型１ｂの金型温度のみを低下させて冷却工程時の所定の温度まで到達させ、その後、上型１ａの金型温度を低下させて上型１ａも冷却工程時の所定の温度に到達させる。
【００１１】
この場合、下型１ｂの温度低下が進行しているとき、射出充填工程時の高温状態の金型温度に保たれた上型１ａにより樹脂４の上型１ａ側は溶融状態のままであり、一方、相対的に温度が低い樹脂４の下型１ｂ側は冷却による凝固が開始される。この際、溶融状態の樹脂４は、相対的に低温の下型１ｂ側から相対的に高温の上型１ａ側の方向に波及的に凝固しながら体積が減少し、これに伴い、下型１ｂから上型１ａ方向に収縮するため、図１（ｃ）に示すように、樹脂４の下型１ｂ側の表面と下型１ｂのキャビティ内表面２ｂとの間に隙間７ｂが生じる。そして、下型１ｂの次に上型１ａの金型温度を低下させると、今度は、樹脂４の上型１ａ側が冷却により凝固し始める。
【００１２】
樹脂４の上型１ａ側の凝固開始に際しては、先行する下型１ｂの金型温度の低下により、既に下型１ｂ側から上型１ａ側に樹脂４の凝固が順次進行しており、樹脂４のうち上型１ａ側の表面近傍が最も凝固の開始が遅れた状態になっている。したがって、樹脂４の上型１ａ側では、下型１ｂ側のような樹脂収縮を伴わずに樹脂４が凝固し、樹脂４の上型１ａ側の表面が上型１ａのキャビティ内表面２ａから離間しない。そして、樹脂４の上型１ａ側が凝固する際に、上型１ａのキャビティ内表面２ａに密着したまま、樹脂４の上型１ａ側の表面がキャビティ内表面２ａの形状を正確に転写して形成される。さらに、上型１ａの金型温度が冷却工程時の所定温度まで低下して樹脂４の上型１ａ側の凝固が完了したときには、樹脂４の上型１ａ側の表面と上型１ａのキャビティ内表面２ａとの間の粘着状態は解消されており、又、樹脂４の下型１ｂ側の表面と下型１ｂのキャビティ内表面２ｂとの間に隙間７ｂが生じていて樹脂４が下型１ｂ側で支持されていないことから、僅少な外力の作用により樹脂４の上型１ａ側の表面を上型１ａのキャビティ内表面２ａから剥離することができ、かくて、樹脂４が上型１ａから離型し易い状態になる。
【００１３】
尚、本実施の形態では、射出充填工程後に樹脂供給路３を閉鎖して、保圧工程を経ずに冷却工程に移行しているが、これは、保圧工程中では、樹脂４が凝固して体積減少した場合も射出機側より樹脂４が補充され、この結果、樹脂４の下型１ｂ側が凝固する際に樹脂４の下型１ｂ側の表面と下型１ｂのキャビティ内表面２ｂとの間に隙間７ｂを生じさせることができず、上記のように樹脂４が上型１ａから離型し易い状態になるのを妨げるおそれがあるからである。
【００１４】
次に、金型１を型締めしたまま、注入路５の注入口５ａを開放し、樹脂４の上型１ａ側の表面と上型１ａのキャビティ内表面２ａとの間にコンプレッサ（図示せず）から圧縮ガスを注入する。この場合、キャビティ内表面２ａの形状を転写した樹脂４の上型１ａ側の表面精度が維持されたまま、樹脂４の上型１ａ側の表面が上型１ａのキャビティ内表面２ａから剥離して樹脂４が上型１ａから離型し、図１（ｄ）に隙間７ａとして示される空間が樹脂４の上型１ａ側の表面と上型１ａのキャビティ内表面２ａとの間に生じる。この際、隙間７ｂは新たに生じた隙間７ａの分だけ容積が減少する。
【００１５】
さらに、金型１を型締めしたまま、図１（ｄ）に示すように、皮膜原料注入機（図示せず）から注入口５ａを介して隙間７ａ内に皮膜原料６を注入して充填する。この場合、皮膜原料６が熱硬化性樹脂を主成分とする場合には、注入時に皮膜原料６の流動性を保てるように、上型１ａと下型１ｂとを低温に保ったまま皮膜原料６を液相状態で注入して充填した後に上型１ａの金型温度を上昇させ、皮膜原料６を熱硬化させて皮膜を形成する。又、皮膜原料６が熱可塑性樹脂を主成分とする場合には、注入時に皮膜原料６の流動性を保てるように、下型１ｂを低温に保ったまま上型１ａを高温にして皮膜原料６を溶融状態で注入して充填した後に上型１ａの金型温度を低下させ、皮膜原料６を凝固させて皮膜を形成する。皮膜原料６が熱硬化性樹脂及び熱可塑性樹脂のいずれの場合も、皮膜原料６は、上記のようにキャビティ内表面２ａの形状を正確に転写して形成された射出成形品の表面と上型１ａのキャビティ内表面２ａとの間に充填されるので、皮膜原料６の固化で形状精度の良い皮膜が形成される。例えば、表面が平滑な成形品を得る場合においては、ひけ等による凹凸の無い、平滑性に優れた成形品を得ることができる。
【００１６】
又、これらの場合、皮膜原料６が、熱可塑性樹脂４から成る射出成形品の上型１ａ側の表面と上型１ａのキャビティ内表面２ａとの間に生じる隙間７ａ内に充填されるので、上型１ａの金型温度を上昇させてもこれにより発生する熱が上記射出成形品に対して直接伝導されることはなく、この熱によりこの射出成形品が再び溶融状態となって上記の皮膜原料６による皮膜の形成が妨げられることはない。
【００１７】
【発明の効果】
以上の説明から明らかなように、本発明によれば、簡易な構造の金型を用いて、熱可塑性樹脂の射出成形工程中に、射出成形品の皮膜形成を行うべき表面に精度良く確実に皮膜を形成することができる。
【図面の簡単な説明】
【図１】（ａ）〜（ｄ）
立て形射出成形機を用いたインモールドコート工程図
【符号の説明】
１ 金型 ２ キャビティ ４ 熱可塑性樹脂 ６ 皮膜原料
７ａ 隙間[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an in-mold coating method for forming a film on the surface of an injection molded product made of a thermoplastic resin during an injection molding process.
[0002]
[Prior art]
Conventionally, according to Japanese Patent Laid-Open No. 7-112450, a gap is generated between the surface of the thermoplastic resin and the inner surface of the cavity while the mold is clamped after injection filling the thermoplastic resin into the cavity. An in-mold coating method is known in which a film raw material is injected to form a film during an injection molding process. In the first aspect of this, the coating material is injected into the gap formed between the resin surface and the cavity inner surface due to the volume reduction when the resin filled in the mold cavity is cooled and solidified. However, it is not certain which side of the resin surface with such a gap with respect to the inner surface of the cavity, that is, which side of the movable mold or the stationary mold forming the cavity, and the resin on the side where film formation is necessary The surface may be formed in an uneven shape due to local depression (sink) due to non-uniform shrinkage during shrinkage due to solidification, and the surface is formed by coating a film raw material on such a surface. There is a problem with the shape accuracy of the coating. For this reason, in the second aspect, a movable core part is provided on the movable mold of the mold, and when the resin is solidified, only the core part is retracted while the mold is closed, so that the movable mold side of the resin A gap is mechanically generated between the surface of the substrate and the core portion, and a film raw material is injected into the gap. Furthermore, in the third aspect, the stationary mold and the movable mold constituting the mold are configured in a nested structure, and a cavity structure is employed in which the resin is fixed to the movable mold side when the resin is solidified. By moving the movable mold back slightly, a gap is mechanically generated between the surface of the fixed mold side of the resin and the inner surface of the cavity of the fixed mold, and the coating material is injected into this gap.
[0003]
[Problems to be solved by the invention]
In the above method, in order to improve the first mode in which the position where the gap is generated with respect to the resin surface is uncertain, in the second mode, the movable core portion is provided in the movable mold of the mold, and the third mode In the aspect, the fixed mold and the movable mold constituting the mold are engaged with each other by a telescopic structure. However, in both aspects, the mold structure is complicated and causes an increase in cost.
[0004]
In view of the above problems, the present invention can form a film with high accuracy on a surface on which a film of an injection molded product is to be formed during a thermoplastic resin injection molding process using a mold having a simple structure. It is an object to provide an in-mold coating method.
[0005]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides an in-mold coating method for forming a film on the surface of an injection-molded product made of a thermoplastic resin in a mold cavity. After the thermoplastic resin is injected and filled in the mold, the mold is clamped while the mold is clamped, and the other mold is positioned on the surface side where the film of the injection molded product is to be formed. With the mold kept at a low temperature, the other mold side of the resin is solidified, then the temperature of the one mold is lowered to solidify the one mold side of the resin, and then the resin A film raw material is injected between the surface on the one mold side and the inner surface of the cavity of the one mold.
[0006]
According to the present invention, when the other mold side of the resin is solidified, a gap is generated between the surface of the other mold side of the resin and the inner surface of the cavity of the other mold due to resin shrinkage accompanying the solidification, When one mold side of the resin is solidified, a resin surface that requires film formation located on one mold side is formed by transferring the shape of the inner surface of the cavity of one mold, The adhesion state between the mold side surface and the inner surface of the cavity of one mold is eliminated. Therefore, when the solidification of one mold side of the resin is completed, the resin surface to which the shape of the inner surface of the cavity of one mold is transferred can be peeled from the inner surface of the cavity of one mold by the action of a slight external force. Also, as described above, there is a gap between the surface of the other mold side of the resin and the cavity inner surface of the other mold, and the resin is not supported on the other mold side, The resin is easily released from one mold. Therefore, after that, the coating material can be injected between the surface of the one mold side of the resin and the inner surface of the cavity of the one mold, and in this way, the coating film can be accurately formed on the surface of the injection molded product. .
[0007]
In this case, if the compressed gas is supplied between the surface of the one mold side of the resin and the inner surface of the cavity of the one mold before the coating material is injected, the cavity of one mold as described above. The resin is released from one mold while maintaining the resin surface formed by transferring the shape of the inner surface, and a gap is formed between the resin surface and the inner surface of the cavity of the one mold, and then The coating material can be easily injected.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
1A to 1D show an in-mold coating process using a vertical injection molding machine. Referring to FIG. 1, reference numeral 1 denotes a main part of a mold of a vertical injection molding machine. The mold 1 includes an upper mold 1a that is a movable mold and a lower mold 1b that is a fixed mold, and the upper mold 1a is a lower mold. A cavity 2 having a required product shape is formed between the upper die 1a and the lower die 1b by clamping the die 1b. In addition, a resin supply port 3b connected to the resin supply path 3 is provided at substantially the center of the cavity inner surface 2b of the lower mold 1b, and molten resin made of thermoplastic resin 4 from the injection machine (not shown) passes through the resin supply path 3 and the cavity 2 In addition, an injection port 5a connected to the injection path 5 is provided in a portion of the cavity inner surface 2a of the upper mold 1a, and a compressor (not shown) and an injector (not shown) are provided in the injection path 5. Any one of the above can be selectively connected, and the compressed gas such as compressed air or nitrogen gas in the compressor and the film raw material 6 in the film raw material injector are connected to the cavity 2 via the injection path 5 and the injection port 5a. It is comprised so that it may selectively inject.
[0009]
At the time of injection molding, first, as shown in FIG. 1 (a), the upper mold 1a and the lower mold 1b of the mold 1 are closed in contact with each other and are closed so as to resist the injection pressure at the time of injection filling. 1 is clamped by a mold clamping device (not shown), and in this state, a molten thermoplastic resin 4 is injected from the injection machine (not shown) into the cavity 2 of the mold 1 through the resin supply port 3b of the supply path 3. Fill. Then, when the cavity 2 is filled with resin, the resin supply path 3 is blocked by an appropriate blocking means to complete the injection filling process. The injection port 5a is closed by an appropriate closing means until injection of a compressed gas or a coating material described later is performed.
[0010]
Next, the mold temperature of the upper mold 1a and the lower mold 1b is lowered while the mold 1 is clamped. At this time, as shown in FIG. While maintaining the mold temperature at the time, only the mold temperature of the lower mold 1b is lowered to reach a predetermined temperature during the cooling process, and then the mold temperature of the upper mold 1a is lowered to lower the upper mold 1a. Also, it reaches a predetermined temperature during the cooling process.
[0011]
In this case, when the temperature decrease of the lower mold 1b is proceeding, the upper mold 1a side of the resin 4 remains in a molten state by the upper mold 1a maintained at a high mold temperature during the injection filling process. On the other hand, the lower mold 1b side of the resin 4 having a relatively low temperature starts to solidify by cooling. At this time, the molten resin 4 is reduced in volume while solidifying in a direction from the relatively low temperature lower mold 1b to the relatively high temperature upper mold 1a, and accordingly, the lower mold 1b. 1c, the gap 7b is formed between the surface of the resin 4 on the lower mold 1b side and the cavity inner surface 2b of the lower mold 1b, as shown in FIG. 1 (c). When the mold temperature of the upper mold 1a is lowered next to the lower mold 1b, the upper mold 1a side of the resin 4 starts to solidify by cooling.
[0012]
When the solidification of the upper mold 1a side of the resin 4 starts, the solidification of the resin 4 has already progressed sequentially from the lower mold 1b side to the upper mold 1a side due to the decrease in the mold temperature of the preceding lower mold 1b. Among them, the vicinity of the surface on the upper mold 1a side is in a state where the start of solidification is most delayed. Therefore, on the upper mold 1a side of the resin 4, the resin 4 is solidified without causing resin shrinkage as in the lower mold 1b side, and the surface of the upper mold 1a side of the resin 4 is separated from the cavity inner surface 2a of the upper mold 1a. do not do. When the upper mold 1a side of the resin 4 is solidified, the surface of the upper mold 1a side of the resin 4 is formed by accurately transferring the shape of the inner surface 2a of the cavity 4 while keeping in close contact with the inner surface 2a of the cavity of the upper mold 1a. Is done. Further, when the mold temperature of the upper mold 1a is lowered to a predetermined temperature during the cooling process and the solidification on the upper mold 1a side of the resin 4 is completed, the surface of the upper mold 1a side of the resin 4 and the cavity of the upper mold 1a The adhesive state between the surface 2a is eliminated, and a gap 7b is formed between the surface of the lower mold 1b side of the resin 4 and the cavity inner surface 2b of the lower mold 1b. Since it is not supported on the side, the surface of the upper mold 1a side of the resin 4 can be peeled from the cavity inner surface 2a of the upper mold 1a by the action of a slight external force. Easy to release.
[0013]
In the present embodiment, the resin supply path 3 is closed after the injection filling process, and the process proceeds to the cooling process without going through the pressure holding process. This is because the resin 4 is solidified during the pressure holding process. Even when the volume is reduced, the resin 4 is replenished from the injection machine side. As a result, when the lower mold 1b side of the resin 4 solidifies, the surface of the lower mold 1b side of the resin 4 and the cavity inner surface 2b of the lower mold 1b This is because the gap 7b cannot be generated between them, and the resin 4 may be prevented from being easily released from the upper mold 1a as described above.
[0014]
Next, with the mold 1 clamped, the injection port 5a of the injection path 5 is opened, and a compressor (not shown) is provided between the surface of the resin 4 on the upper mold 1a side and the cavity inner surface 2a of the upper mold 1a. ) To inject compressed gas. In this case, the surface of the upper mold 1a side of the resin 4 to which the shape of the cavity inner surface 2a is transferred is maintained, and the surface of the upper mold 1a side of the resin 4 is peeled off from the cavity inner surface 2a of the upper mold 1a. The resin 4 is released from the upper mold 1a, and a space shown as a gap 7a in FIG. 1 (d) is formed between the surface of the resin 4 on the upper mold 1a side and the cavity inner surface 2a of the upper mold 1a. At this time, the volume of the gap 7b decreases by the amount of the newly created gap 7a.
[0015]
Further, with the mold 1 clamped, as shown in FIG. 1D, the coating material 6 is injected into the gap 7a from the coating material injection machine (not shown) through the injection port 5a and filled. . In this case, when the film raw material 6 is mainly composed of a thermosetting resin, the film raw material 6 is maintained while keeping the upper mold 1a and the lower mold 1b at a low temperature so that the fluidity of the film raw material 6 can be maintained at the time of injection. After filling and filling in a liquid phase state, the mold temperature of the upper mold 1a is raised, and the film raw material 6 is thermally cured to form a film. Further, when the film material 6 is mainly composed of a thermoplastic resin, the film material 6 is made by keeping the lower mold 1b at a low temperature while keeping the lower mold 1b at a low temperature so that the fluidity of the film material 6 can be maintained at the time of injection. Is injected in a molten state and filled, and then the mold temperature of the upper die 1a is lowered to solidify the coating material 6 to form a coating. In the case where the film raw material 6 is either a thermosetting resin or a thermoplastic resin, the film raw material 6 is formed by accurately transferring the shape of the cavity inner surface 2a as described above and the upper mold surface. Since it fills between the cavity inner surfaces 2a of 1a, the film | membrane raw material 6 solidifies and a film | membrane with a sufficient shape precision is formed. For example, in the case of obtaining a molded product having a smooth surface, it is possible to obtain a molded product excellent in smoothness without unevenness due to sink marks or the like.
[0016]
In these cases, the coating material 6 is filled in the gap 7a formed between the surface of the upper mold 1a side of the injection molded product made of the thermoplastic resin 4 and the cavity inner surface 2a of the upper mold 1a. Even if the mold temperature of the upper mold 1a is raised, the heat generated thereby is not directly conducted to the injection molded product, and this injection molded product is again melted by this heat. The formation of the film by the raw material 6 is not hindered.
[0017]
【The invention's effect】
As is apparent from the above description, according to the present invention, a mold having a simple structure is used to accurately and reliably provide a surface on which a film of an injection molded product is to be formed during the thermoplastic resin injection molding process. A film can be formed.
[Brief description of the drawings]
FIG. 1 (a) to (d)
In-mold coating process diagram using vertical injection molding machine 【Explanation of symbols】
1 Mold 2 Cavity 4 Thermoplastic resin 6 Film material 7a Crevice

Claims (2)

金型のキャビティ内の熱可塑性樹脂から成る射出成形品の表面に皮膜を形成するインモールドコート方法において、金型を型締めした状態で金型のキャビティ内に熱可塑性樹脂を射出充填した後、金型を型締めしたまま金型を構成する１対の型のうち射出成形品の皮膜を形成すべき表面側に位置する一方の型よりも他方の型を低温に保った状態で、前記樹脂の該他方の型側を凝固させ、次に、前記一方の型の温度を低下させて前記樹脂の該一方の型側を凝固させ、その後、該樹脂の前記一方の型側の表面と該一方の型のキャビティ内表面との間に皮膜原料を注入することを特徴とするインモールドコート方法。In an in-mold coating method in which a film is formed on the surface of an injection molded product made of a thermoplastic resin in a mold cavity, after the mold is clamped, the thermoplastic resin is injected and filled into the mold cavity. The resin in a state in which the other mold is kept at a lower temperature than one mold located on the surface side where the film of the injection molded product is to be formed, of a pair of molds constituting the mold while the mold is clamped The other mold side of the resin is then solidified, and then the temperature of the one mold is lowered to solidify the one mold side of the resin, and then the surface of the one mold side of the resin and the one An in-mold coating method comprising injecting a coating material between the inner surface of the mold and the cavity. 前記皮膜原料の注入前に、前記樹脂の前記一方の型側の表面と該一方の型のキャビティ内表面との間に圧縮ガスを供給して隙間を生じさせることを特徴とする請求項１に記載のインモールドコート方法。The compressed gas is supplied between the surface of the one mold side of the resin and the inner surface of the cavity of the one mold to inject a gap before the coating material is injected. The in-mold coating method as described.
JP2000289228A 2000-09-22 2000-09-22 In-mold coating method Expired - Fee Related JP4233005B2 (en)

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Publication number Priority date Publication date Assignee Title
CN102166804A (en) * 2009-12-11 2011-08-31 株式会社富士精工 Injection forming method

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DE10221558B4 (en) 2002-05-15 2005-07-21 Krauss-Maffei Kunststofftechnik Gmbh Mold part, mold and method for injection molding plastic articles
JP5081748B2 (en) * 2008-07-09 2012-11-28 本田技研工業株式会社 In-mold coating method

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102166804A (en) * 2009-12-11 2011-08-31 株式会社富士精工 Injection forming method

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