JP5803592B2 - Method for producing foamed resin molded body - Google Patents

Method for producing foamed resin molded body Download PDF

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JP5803592B2
JP5803592B2 JP2011248724A JP2011248724A JP5803592B2 JP 5803592 B2 JP5803592 B2 JP 5803592B2 JP 2011248724 A JP2011248724 A JP 2011248724A JP 2011248724 A JP2011248724 A JP 2011248724A JP 5803592 B2 JP5803592 B2 JP 5803592B2
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pin member
layer
skin layer
foamed
cavity
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JP2013103404A (en
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嗣久 宮本
嗣久 宮本
小川　淳一
淳一 小川
金子　満晴
満晴 金子
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Mazda Motor Corp
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本発明は発泡樹脂成形体の製造方法に関する。   The present invention relates to a method for producing a foamed resin molded body.

従来より、例えば自動車用部品などの種々の工業用部品の分野において、軽量性、断熱性及び防音性等の優れた特性を有する発泡樹脂成形体が幅広く採用されている。このような発泡樹脂成形体は、使用される目的及び用途などに応じて好適な樹脂材料を選定し、また、成形体内部の気泡の形態や発泡倍率などの諸条件を設定して成形されている。   Conventionally, in the field of various industrial parts such as automobile parts, foamed resin molded articles having excellent characteristics such as lightness, heat insulation and soundproofing have been widely adopted. Such a foamed resin molded body is molded by selecting a suitable resin material according to the purpose and application to be used, and by setting various conditions such as the form of bubbles inside the molded body and the expansion ratio. Yes.

その成形方法の一例として、樹脂に発泡剤を含有させた溶融状態の発泡性樹脂を固定型と可動型とでなる成形型のキャビティに充填した後に、可動型を型開き方向に移動させてキャビティの容積を拡大することにより、発泡性樹脂の発泡を促進させるようにした所謂コアバック法が知られている。このコアバック法によれば、キャビティに充填した発泡性樹脂が成形型によって表面から冷却されることにより、発泡樹脂成形体の表面に表皮層として非発泡のスキン層が形成され、該スキン層の内側にコアバックによる発泡促進によって得られた発泡層が形成される。つまり、非発泡の表皮層間に発泡層が一体的に挟まれた形態の成形体が得られる。   As an example of the molding method, after filling a moldable mold cavity composed of a fixed mold and a movable mold with a molten foamable resin containing a foaming agent in the resin, the movable mold is moved in the mold opening direction and the cavity is moved. A so-called core back method is known in which foaming of a foamable resin is promoted by enlarging the volume of the foamed resin. According to this core back method, the foamable resin filled in the cavity is cooled from the surface by the molding die, so that a non-foamed skin layer is formed as a skin layer on the surface of the foamed resin molded body. A foam layer obtained by promoting foaming by the core back is formed inside. That is, a molded body in which the foamed layer is integrally sandwiched between the non-foamed skin layers is obtained.

このような発泡樹脂成形体を断熱材や防音材（吸音材）としてそのまま使用すると、表面に非発泡のスキン層があるため、内部の発泡層が有する断熱効果や防音効果が十分に発揮されないと言う問題がある。すなわち、表面のスキン層の熱伝導率が大きいためまわりに熱が伝わりやすくなり、或いはスキン層によって音が反射され易くなる。   If such a foamed resin molded article is used as it is as a heat insulating material or a soundproofing material (sound absorbing material), there is a non-foamed skin layer on the surface, so that the heat insulating effect and soundproofing effect of the internal foamed layer may not be sufficiently exhibited. There is a problem to say. That is, since the heat conductivity of the skin layer on the surface is large, heat is easily transmitted to the surroundings, or sound is easily reflected by the skin layer.

これに対して、断熱効果や防音効果を高めるべく、表面に形成されたスキン層を取り除き、内部の発泡層を露出させることが考えられる。   On the other hand, it is conceivable to remove the skin layer formed on the surface and to expose the internal foamed layer in order to enhance the heat insulating effect and the soundproofing effect.

発泡樹脂成形体のスキン層を除去することに関して、例えば、特許文献１には、断熱効果や防音効果の向上を狙いとするものではないが、片面に接着性シートを積層したシート状発泡体を成形し、このシート状発泡体の反対側の面に形成されているスキン層全体をスライス刃によって除去することが記載されている。   Regarding removal of the skin layer of the foamed resin molded body, for example, Patent Document 1 does not aim to improve the heat insulation effect and the soundproofing effect, but a sheet-like foam body in which an adhesive sheet is laminated on one side is disclosed. It is described that the entire skin layer formed and formed on the opposite surface of the sheet-like foam is removed by a slicing blade.

また、特許文献２には、可動型にピン部材を組み込んでおき、溶融状態の発泡性樹脂をキャビティに充填した後、ピン部材を可動型と共にコアバックさせ、次いでピン部材を前進させてキャビティ内に押し込むことにより、発泡樹脂成形体に凹部を形成することが記載されている。   In Patent Document 2, a pin member is incorporated into a movable mold, and after filling the cavity with a molten foamable resin, the pin member is core-backed together with the movable mold, and then the pin member is advanced to move into the cavity. It is described that a concave portion is formed in a foamed resin molded body by being pushed into the resin.

特開平６−３４４４５９号公報JP-A-6-344459 特開２００９−２２６７８４号公報JP 2009-226784 A

上記特許文献１に記載された方法では、発泡樹脂成形体の成形工程とは別にスキン層除去工程を設ける必要があり、工数が多くなるとともに、スライス刃及びスライス刃を受けるロールを設ける必要があって装置全体も大掛かりになる。また、この方法は、発泡樹脂成形体のスキン層全体をスライスするというものであり、スキン層を所望位置及び所望形態で部分的に除去するという要望には応えることができない。   In the method described in Patent Document 1, it is necessary to provide a skin layer removing step separately from the molding step of the foamed resin molded body, which requires more man-hours and a slice blade and a roll for receiving the slice blade. As a result, the entire apparatus becomes large. In addition, this method is to slice the entire skin layer of the foamed resin molded body, and cannot meet the demand of partially removing the skin layer at a desired position and in a desired form.

また、上記特許文献２に記載された方法は、発泡樹脂成形体の表面に形成されたスキン層をピン部材にて凹状に変形させて発泡層内部に押し込むものであり、期待する断熱効果及び吸音効果の向上が望めず、さらに、吸音性に関しては、ピン部材によってスキン層表面に形成された凹部が逆に異音（空力音）の発生源になるおそれもある。   Further, the method described in Patent Document 2 is a method in which a skin layer formed on the surface of a foamed resin molded body is deformed into a concave shape with a pin member and pushed into the foamed layer, and the expected heat insulation effect and sound absorption The improvement of the effect cannot be expected, and with respect to sound absorption, the concave portion formed on the skin layer surface by the pin member may be a source of abnormal noise (aerodynamic sound).

そこで、本発明は、表面のスキン層が部分的に打ち抜かれて内部の発泡層が露出した発泡樹脂成形体を得る方法を提供する。   Therefore, the present invention provides a method for obtaining a foamed resin molded article in which the skin layer on the surface is partially punched to expose the internal foamed layer.

本発明は、上記課題を解決するために、発泡層がスキン層で覆われてなる発泡樹脂成形体をキャビティ内に成形した後、固定型及び可動型の少なくとも一方に設けられたピン部材を上記キャビティ内に突き入れることにより、上記スキン層を打ち抜くようにした。   In order to solve the above problems, the present invention provides a pin member provided on at least one of a fixed mold and a movable mold after molding a foamed resin molded body having a foam layer covered with a skin layer in a cavity. The skin layer was punched by piercing into the cavity.

すなわち、ここに提示する発泡樹脂成形体の製造方法は、発泡層がスキン層で覆われ、且つそのスキン層の一部が発泡層内に打ち抜かれ当該打抜き孔の内周面に発泡層が露出してなる発泡樹脂成形体を得る方法であって、
上記発泡樹脂成形体成形用のキャビティを形成する固定型及び可動型の少なくとも一方は型本体とピン部材とを備え、該ピン部材はその先端面が当該型本体の成形面と共に上記キャビティを形成しており、
上記ピン部材の先端面の熱伝導率、又は上記ピン部材の先端面及び該ピン部材の先端面を囲む上記成形面の環状部分の熱伝導率が、そのまわりの上記成形面の熱伝導率よりも低く、
原料樹脂に発泡剤を含ませてなる溶融状態の発泡性樹脂を上記キャビティに充填することにより、上記発泡層がスキン層で覆われてなる発泡樹脂成形体をそのキャビティ内に成形した後、
上記ピン部材を上記キャビティ内に突き入れることにより、上記スキン層を打ち抜いて当該打抜き孔の内周面に上記発泡層を露出させることを特徴とする。 That is, in the method for producing a foamed resin molded body presented here, the foamed layer is covered with a skin layer, and a part of the skin layer is punched into the foamed layer, and the foamed layer is exposed on the inner peripheral surface of the punched hole. A method for obtaining a foamed resin molded article comprising:
At least one of a fixed mold and a movable mold that form a cavity for molding the foamed resin molded body includes a mold body and a pin member, and the tip end surface of the pin member forms the cavity together with a molding surface of the mold body. And
The thermal conductivity of the tip surface of the pin member, or the thermal conductivity of the annular surface portion of the molding surface surrounding the tip surface of the pin member and the tip surface of the pin member is based on the thermal conductivity of the molding surface around it. Too low,
After filling the cavity with a foamable resin in a molten state containing a foaming agent in the raw resin, the foamed resin molded body in which the foamed layer is covered with a skin layer is molded into the cavity.
By pushing the pin member into the cavity, the skin layer is punched to expose the foam layer on the inner peripheral surface of the punch hole.

従って、本発明によれば、スキン層をスライスすることなく、ピン部材によるスキン層の打ち抜きによって簡単に、発泡樹脂成形体の発泡層を所望の位置で且つピン部材の断面形状に対応する所望の形態で露出させることができる。   Therefore, according to the present invention, the foam layer of the foamed resin molded body can be easily formed at a desired position and corresponding to the cross-sectional shape of the pin member by simply punching the skin layer with the pin member without slicing the skin layer. It can be exposed in form.

また、上記ピン部材の先端面の熱伝導率を上記型本体の成形面の熱伝導率よりも低くし、或いは、上記ピン部材の先端面及び該ピン部材の先端面を囲む上記成形面の環状部分の熱伝導率を、そのまわりの上記成形面の熱伝導率よりも低くしたことにより、当該熱伝導率が低い部位では発泡性樹脂の冷却速度が緩慢になってスキン層がそのまわりよりも薄くなり、ピン部材によるスキン層の打ち抜きが容易になる。 Further , the thermal conductivity of the tip surface of the pin member is made lower than the thermal conductivity of the molding surface of the mold body , or the annular shape of the molding surface surrounding the tip surface of the pin member and the tip surface of the pin member By making the thermal conductivity of the part lower than the thermal conductivity of the molding surface around it , the cooling rate of the foaming resin becomes slow at the part where the thermal conductivity is low, and the skin layer is more than the surroundings. It becomes thin and the punching of the skin layer by the pin member becomes easy.

好ましい実施形態では、上記原料樹脂をポリプロピレンとし、上記ピン部材を上記キャビティ内に突き入れる速度を１５ｍｍ／ｓ以上１９ｍｍ／ｓ以下とし、上記キャビティ内に、上記速度でのスキン層のせん断強さτｆが１３．８Ｎ／ｍｍ２以上１８．０Ｎ／ｍｍ２以下、発泡層の圧縮降伏強さσｃが２．０Ｎ／ｍｍ２以上２．６Ｎ／ｍｍ２以下であり且つ上記スキン層の最大せん断荷重が上記発泡層の最大圧縮降伏荷重よりも小さい発泡樹脂成形体を成形する。これにより、スキン層を確実に打ち抜いて発泡層を露出させることができる。 In a preferred embodiment, the raw material resin is polypropylene, the speed at which the pin member is pushed into the cavity is 15 mm / s or more and 19 mm / s or less, and the shear strength τf of the skin layer at the speed in the cavity. There 13.8N / mm 2 or more 18.0N / mm 2 or less, compressive yield strength σc of the foamed layer is the maximum shear load of 2.0 N / mm 2 or more 2.6 N / mm 2 or less and and said skin layer you small foam the resin molded body formed shape than the maximum compressive yield load of the foamed layer. Thereby, the skin layer can be surely punched to expose the foam layer.

以上のように、本発明によれば、ピン部材の先端面の熱伝導率、又はピン部材の先端面及び該ピン部材の先端面を囲む上記成形面の環状部分の熱伝導率を、そのまわりの上記成形面の熱伝導率よりも低くし、発泡性樹脂を成形型のキャビティに充填することにより、発泡層がスキン層で覆われてなる発泡樹脂成形体を成形した後、ピン部材を上記キャビティ内に突き入れることにより、上記スキン層を打ち抜いて当該打抜き孔の内周面に上記発泡層を露出させるようにしたから、上記熱伝導率が低い部位では発泡性樹脂の冷却速度が緩慢になってスキン層がそのまわりよりも薄くなり、そのため、ピン部材によるスキン層の打ち抜きが容易になり、簡単に、発泡樹脂成形体の発泡層を所望位置で且つピン部材の断面形状に対応する所望の形態で露出させることができる。 As described above, according to the present invention, the thermal conductivity of the tip surface of the pin member, or the thermal conductivity of the annular portion of the molding surface surrounding the tip surface of the pin member and the tip surface of the pin member, After molding the foamed resin molded body in which the foamed layer is covered with the skin layer by filling the cavity of the mold with a foamable resin lower than the thermal conductivity of the molding surface , the pin member is By piercing into the cavity, the skin layer is punched to expose the foamed layer on the inner peripheral surface of the punched hole, so that the cooling rate of the foamable resin is slow at the portion where the thermal conductivity is low. Therefore, the skin layer becomes thinner than the surroundings, so that the punching of the skin layer by the pin member is facilitated, and the foam layer of the foamed resin molded body can be easily obtained at the desired position and corresponding to the cross-sectional shape of the pin member. Form of It can be exposed.

発泡樹脂成形体の製造装置の全体構成を示す図である。It is a figure which shows the whole structure of the manufacturing apparatus of a foamed resin molding. コアバック途中の成形型の状態を示す断面図である。It is sectional drawing which shows the state of the shaping | molding die in the middle of a core back. コアバック終了後にピン部材を発泡樹脂成形体の発泡層に突き入れた状態を示す断面図である。It is sectional drawing which shows the state which pushed the pin member into the foaming layer of the foaming resin molding after completion | finish of a core back. ピン部材を発泡樹脂成形体の発泡層に突き入れた状態を示す拡大断面図である。It is an expanded sectional view showing the state where the pin member was pushed into the foamed layer of the foamed resin molded body. 発泡樹脂成形体の一部を示す断面図である。It is sectional drawing which shows a part of foaming resin molding. スキン層の打ち抜き不良例を示す断面図である。It is sectional drawing which shows the punching defect example of a skin layer. スキン層の打ち抜き不良の他の例を示す断面図である。It is sectional drawing which shows the other example of the punching defect of a skin layer.

以下、本発明を実施するための形態を図面に基づいて説明する。以下の好ましい実施形態の説明は、本質的に例示に過ぎず、本発明、その適用物或いはその用途を制限することを意図するものではない。   Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the invention, its application, or its use.

＜発泡樹脂成形体の製造装置の構成＞
図１に示す発泡樹脂成形体の製造装置において、１は発泡樹脂成形体の成形型、２は成形型１のキャビティ３に溶融状態の発泡性樹脂を充填する充填手段としての射出装置である。成形型１は、固定型４と、該固定型４に向かって進退するように設けられた可動型５とを備えてなり、固定型４と可動型５とによってキャビティ３が形成されている。固定型４にスプルー６が設けられている。 <Configuration of manufacturing apparatus for foamed resin molding>
In the foamed resin molded body manufacturing apparatus shown in FIG. 1, reference numeral 1 denotes a foamed resin molded body mold, and 2 denotes an injection apparatus as a filling means for filling the cavity 3 of the mold 1 with a molten foamable resin. The mold 1 includes a fixed mold 4 and a movable mold 5 provided so as to advance and retreat toward the fixed mold 4, and a cavity 3 is formed by the fixed mold 4 and the movable mold 5. A sprue 6 is provided on the fixed mold 4.

可動型５は、可動型本体７とピン部材８とを備えてなる。ピン部材８は、固定型４に向かって進退できるように、可動型本体７に形成されたピン孔９に挿入されている。すなわち、ピン部材８は、その先端面が可動型本体７と共にキャビティ３を形成するように且つ固定型４の成形面に対向するように設けられている。   The movable mold 5 includes a movable mold body 7 and a pin member 8. The pin member 8 is inserted into a pin hole 9 formed in the movable mold body 7 so that the pin member 8 can move forward and backward toward the fixed mold 4. That is, the pin member 8 is provided so that the tip surface thereof forms the cavity 3 together with the movable mold body 7 and faces the molding surface of the fixed mold 4.

成形型１には、可動型本体７を固定型４に向かって進退させる可動型本体駆動手段１１と、ピン部材８を固定型４に向かって進退させるピン部材駆動手段１２とが接続されている。それら駆動手段１１，１２はコントローラ１３によって制御される。なお、図１ではピン部材８が１本のみ示されているが、防音用又は断熱用の発泡樹脂成形体の成形においては複数のピン部材８を可動型５に設けることになる。   Connected to the mold 1 are movable body drive means 11 for moving the movable body 7 forward and backward toward the fixed mold 4 and pin member drive means 12 for moving the pin member 8 forward and backward toward the fixed mold 4. . These driving means 11 and 12 are controlled by a controller 13. Although only one pin member 8 is shown in FIG. 1, a plurality of pin members 8 are provided on the movable die 5 in molding a foamed resin molded body for soundproofing or heat insulation.

射出装置２は、内部にスクリュー１５が回転自在に挿入され外周面に加熱用ヒータが設けられたシリンダ１６を備え、シリンダ１６の先端のノズルが固定型４のスプルー６に接続されている。シリンダ１６の基端側には、ＰＰ（ポリプロピレン）樹脂等の原料樹脂１７を供給するためのホッパ１８と、スクリューの回転及び進退を行なうためのスクリュー駆動手段１９とが設けられている。シリンダ１６の中間部には、物理発泡剤として超臨界状態の流体を注入するノズル２１が接続されている。ノズル２１には、ボンベ２２から送られる不活性ガス（二酸化炭素、窒素等）が超臨界状態発生装置２３にて超臨界状態にされて供給される。この場合、原料樹脂１７は、ヒータによる加熱とスクリュー１５による練りとによって溶融し、さらに上記発泡剤と共に混練されて、溶融状態の発泡性樹脂２４となってスプルー６から成形型１のキャビティ３に供給される。   The injection device 2 includes a cylinder 16 in which a screw 15 is rotatably inserted and a heating heater is provided on an outer peripheral surface. A nozzle at the tip of the cylinder 16 is connected to the sprue 6 of the fixed mold 4. A hopper 18 for supplying a raw material resin 17 such as PP (polypropylene) resin and a screw driving means 19 for rotating and advancing and retracting the screw are provided on the base end side of the cylinder 16. A nozzle 21 for injecting a fluid in a supercritical state as a physical foaming agent is connected to an intermediate portion of the cylinder 16. An inert gas (carbon dioxide, nitrogen, etc.) sent from a cylinder 22 is supplied to the nozzle 21 in a supercritical state by a supercritical state generator 23. In this case, the raw material resin 17 is melted by heating with a heater and kneading with the screw 15, and further kneaded with the foaming agent to form a foamable resin 24 in a molten state from the sprue 6 to the cavity 3 of the mold 1. Supplied.

なお、化学発泡剤（例えば、三協化成株式会社製セルマイクMB3274（NaHCO３））を含有する発泡性樹脂を用いて成形を行なう場合には、その発泡剤を原料樹脂１３と共にホッパ１８に投入する。繊維強化発泡樹脂成形体を得る場合は、補強用繊維を予め原料樹脂１７に混入させておけばよい。 When molding is performed using a foamable resin containing a chemical foaming agent (for example, Cellmice MB3274 (NaHCO 3 ) manufactured by Sankyo Kasei Co., Ltd.), the foaming agent is put into the hopper 18 together with the raw material resin 13. . When obtaining a fiber-reinforced foamed resin molded body, reinforcing fibers may be mixed in the raw material resin 17 in advance.

＜発泡樹脂成形体の製造＞
コントローラ１３は、発泡性樹脂２４を固定型４と可動型５との間のキャビティ３に充填した後、駆動手段１１，１２を制御して、図２及び図３に示すように可動型５を固定型４から後退させるコアバックを行なう。これにより、キャビティ３を成形すべき発泡樹脂成形体２７に応じた容積に拡張させる。このコアバックにおいては、ピン部材８は可動型本体７と共に同じ速度で同じ距離後退する。 <Manufacture of foamed resin molding>
The controller 13 fills the cavity 3 between the fixed mold 4 and the movable mold 5 with the foamable resin 24, and then controls the driving means 11 and 12 to move the movable mold 5 as shown in FIGS. The core back is retracted from the fixed mold 4. Thereby, the cavity 3 is expanded to a volume corresponding to the foamed resin molded body 27 to be molded. In this core back, the pin member 8 moves backward with the movable body 7 at the same speed and at the same distance.

そうして、コントローラ１３は、キャビティ３内に形成された発泡樹脂成形体２７の冷却中に、図３及び図４に示すように、ピン部材８を前進させてその先端面を発泡樹脂成形体２７の発泡層２６内に入るようにキャビティ３内に突き入れる。これにより、図５に示すように、ピン部材８に対応する部位に打抜き孔２８が開き、この打抜き孔２８の内周面に発泡層２６が露出した発泡樹脂成形体２７が得られる。   Then, the controller 13 advances the pin member 8 during the cooling of the foamed resin molded body 27 formed in the cavity 3 and the front end surface thereof is foamed resin molded body as shown in FIGS. It pushes into the cavity 3 so that it may enter in the foam layer 26 of 27. As a result, as shown in FIG. 5, the punched hole 28 is opened in the portion corresponding to the pin member 8, and the foamed resin molded body 27 in which the foamed layer 26 is exposed on the inner peripheral surface of the punched hole 28 is obtained.

よって、得られた発泡樹脂成形体２７では、打抜き孔２８の内周面に露出した発泡層２６が音を吸収するため、防音効果が高くなる。また、断熱性に関しても、発泡樹脂成形体２７のスキン層２５に打抜き孔２８があいているから、スキン層２５を伝わる表面の熱伝導率が低くなり、断熱効果が高くなる。   Therefore, in the obtained foamed resin molded body 27, since the foamed layer 26 exposed on the inner peripheral surface of the punch hole 28 absorbs sound, the soundproofing effect is enhanced. Further, regarding the heat insulation, since the punched hole 28 is formed in the skin layer 25 of the foamed resin molded body 27, the thermal conductivity of the surface transmitted through the skin layer 25 is lowered, and the heat insulation effect is enhanced.

スキン層２５を打ち抜くためのピン部材８の前進突き入れは、理論的には次の式１及び式２を満足する条件で行なうことになる。   The forward insertion of the pin member 8 for punching the skin layer 25 is theoretically performed under the conditions satisfying the following expressions 1 and 2.

Qf max(v)＜Cc max(v)＋Cgas max(v) ……式１
Cpin(v)＞Qf max(v)＋Cc max(v)＋Cgas max(v) ……式２
Cpin(v)はピン部材８がスキン層２５に与える圧縮力、Qf max(v)はスキン層２５の最大せん断荷重、Cc max(v)は発泡層２６の最大圧縮降伏荷重、Cgas max(v)は発泡ガスの最大圧縮荷重である。ピン部材８が円柱状であるとき、その直径をｄ、スキン層２５のせん断強さをτf(v)、スキン層２５の厚みをｔf、発泡ガス圧力をPgas(v)、発泡層２６の圧縮降伏強さをσc(v) とすると、次のようになり、いずれも、ピン部材８の前進速度ｖに依存する（速度ｖが大きくなるほどそれら荷重は大きくなる。）。 Qf max (v) <Cc max (v) + Cgas max (v) ...... Formula 1
Cpin (v)> Qf max (v) + Cc max (v) + Cgas max (v) ...... Formula 2
Cpin (v) is the compressive force applied to the skin layer 25 by the pin member 8, Qf max (v) is the maximum shear load of the skin layer 25, Cc max (v) is the maximum compressive yield load of the foam layer 26, Cgas max (v ) Is the maximum compressive load of the foaming gas. When the pin member 8 is cylindrical, the diameter is d, the shear strength of the skin layer 25 is τf (v), the thickness of the skin layer 25 is tf, the foaming gas pressure is Pgas (v), and the compression of the foamed layer 26 is performed. Assuming that the yield strength is σc (v), the following is obtained, and both depend on the forward speed v of the pin member 8 (the higher the speed v, the larger the load).

スキン層２５の最大せん断荷重；Qf max(v)＝π・ｄ・ｔf・τf(v)
発泡層２６の最大圧縮降伏荷重；Cc max(v)＝π・ｄ２／４・σc(v)
発泡ガスの最大圧縮荷重； Cgas max(v)＝π・ｄ２／４・Pgas(v)
ここに、式１に関し、仮に「Qf max(v)≧Cc max(v)＋Cgas max(v)」であれば、式２を満足する条件でピン部材８をキャビティ３に突き入れても、図６に示すように、スキン層２５がせん断されることなく発泡層２６が圧縮されて、スキン層２５に肩だれ２５ａを生じ、或いは、図７に示すように、ピン部材８によるスキン層２５の発泡層２６内への引き込み２５ｂを生じる。すなわち、スキン層２５を確実に打ち抜くこと（発泡層２６を露出させること）が難しくなる。特に、ピン部材８の前進速度ｖを低下させたときにスキン層２５の打ち抜きが難しくなる。 Maximum shear load of skin layer 25; Qf max (v) = π · d · tf · τf (v)
Maximum compressive yield load of the foam layer 26; Cc max (v) = π · d 2/4 · σc (v)
Maximum compressive load of foaming gas; Cgas max (v) = π · d 2/4 · Pgas (v)
Here, if “Qf max (v) ≧ Cc max (v) + Cgas max (v)” with respect to the expression 1, even if the pin member 8 is inserted into the cavity 3 under the condition that satisfies the expression 2, 6, the foamed layer 26 is compressed without shearing the skin layer 25, and a shoulder 25 a is generated in the skin layer 25, or the skin layer 25 of the pin member 8 is formed as shown in FIG. 7. A pull-in 25b into the foam layer 26 is produced. That is, it is difficult to surely punch out the skin layer 25 (expose the foam layer 26). In particular, the punching of the skin layer 25 becomes difficult when the forward speed v of the pin member 8 is reduced.

＜実施例＞
次に示す発泡性樹脂材料条件、射出成形装置条件及び成形手順にて発泡樹脂成形体を得た。 <Example>
A foamed resin molded body was obtained under the following foamable resin material conditions, injection molding apparatus conditions, and molding procedure.

−材料・装置条件−
原料樹脂：住友化学株式会社製ポリプロピレン
発泡剤：Ｎ２
射出成形装置：株式会社日本製鋼所製，型締力＝８５０トン
成形条件：発泡性樹脂温度＝２００℃、型温度＝６０℃
射出速度：２００ｍｍ／ｓ（射出圧力：１００ＭＰａ）
キャビティ容量：型閉じ状態で３３６ｃｍ３（縦６０ｃｍ×横４０ｃｍ×幅０．１４ｃｍの直方体）
ピン部材８の直径：１０ｍｍ
−成形手順−
イ．成形型１を閉じた状態で、シリンダ１６から幅１．４ｍｍのキャビティ３に発泡性樹脂（原料樹脂＋発泡剤）２４を射出充填する。 −Material / Equipment Conditions−
Raw material resin: polypropylene manufactured by Sumitomo Chemical Co., Ltd. Foaming agent: N 2
Injection molding apparatus: manufactured by Nippon Steel Works, mold clamping force = 850 tons Molding conditions: foaming resin temperature = 200 ° C., mold temperature = 60 ° C.
Injection speed: 200 mm / s (injection pressure: 100 MPa)
Cavity capacity: 336 cm 3 in a mold-closed state (a rectangular parallelepiped having a length of 60 cm × width of 40 cm × width of 0.14 cm)
Diameter of pin member 8: 10 mm
-Molding procedure-
A. With the mold 1 closed, a foamable resin (raw material resin + foaming agent) 24 is injected and filled from the cylinder 16 into the cavity 3 having a width of 1.4 mm.

ロ．可動型本体７をピン部材８と共に４．２ｍｍ後退（コアバック）させる。   B. The movable body 7 is retracted 4.2 mm (core back) together with the pin member 8.

ハ．コアバック完了後、ピン部材８を圧縮力Cpin(v)＝６５０Ｎ、前進速度１７ｍｍ／ｓでキャビティ３内に４．５ｍｍ突き入れ、４０秒間冷却して発泡樹脂成形体２７を取り出す。   C. After the core back is completed, the pin member 8 is inserted 4.5 mm into the cavity 3 at a compression force Cpin (v) = 650 N and a forward speed of 17 mm / s, cooled for 40 seconds, and the foamed resin molded body 27 is taken out.

−結果−
図５に示すように、スキン層２５が打ち抜かれ、その打抜き孔２８の内面に発泡層２６が露出した発泡樹脂成形体２７を得ることができた。 -Result-
As shown in FIG. 5, a foamed resin molded body 27 in which the skin layer 25 was punched and the foamed layer 26 was exposed on the inner surface of the punched hole 28 could be obtained.

上記ピン部材８の突き入れにおいて、スキン層２５の最大せん断荷重Qf max(v)は１５０Ｎ、発泡層２６の最大圧縮降伏荷重Cc max(v)は１８０Ｎ、発泡ガスの最大圧縮荷重Cgas max(v)は０Ｎであった。すなわち、発泡層２６の発泡ガス圧力Pgas(v)が零になった後にピン部材８の前進突き入れを行なっている。   In the insertion of the pin member 8, the maximum shear load Qf max (v) of the skin layer 25 is 150 N, the maximum compressive yield load Cc max (v) of the foam layer 26 is 180 N, and the maximum compressive load Cgas max (v ) Was 0N. That is, the pin member 8 is pushed forward after the foaming gas pressure Pgas (v) of the foamed layer 26 becomes zero.

実施例の場合、ピン部材８の直径ｄは１０ｍｍ、スキン層２５の厚さは０．３ｍｍである。従って、スキン層２５のせん断強さτf(v)は１５．９Ｎ／ｍｍ２であり、発泡層２６の圧縮降伏強さσc(v)は２．３Ｎ／ｍｍ２である。これらはピン部材８の前進速度が１７ｍｍ／ｓのときの値であるが、発泡樹脂成形体に対して静的に荷重が加えられた場合のせん断強さτf及び圧縮降伏強さσcも殆ど同じ値になる。 In the embodiment, the diameter d of the pin member 8 is 10 mm, and the thickness of the skin layer 25 is 0.3 mm. Accordingly, the shear strength τf (v) of the skin layer 25 is 15.9 N / mm 2 , and the compression yield strength σc (v) of the foam layer 26 is 2.3 N / mm 2 . These are values when the forward speed of the pin member 8 is 17 mm / s, but the shear strength τf and the compression yield strength σc when the load is statically applied to the foamed resin molded body are almost the same. Value.

型温度、射出速度、コアバック速度、ピン部材８の前進速度等を適宜変化させてスキン層２の打ち抜きを行なったところ、スキン層２５のせん断強さτfが１３．８Ｎ／ｍｍ２以上１８．０Ｎ／ｍｍ２以下であり、発泡層２６の圧縮降伏強さσcが２．０Ｎ／ｍｍ２以上２．６Ｎ／ｍｍ２以下であり、且つスキン層２５の最大せん断荷重Qf max(v)が発泡層２６の最大圧縮降伏荷重Cc max(v)よりも小さいときは、ピン部材８の前進速度を１５ｍｍ／ｓ以上１９ｍｍ／ｓ以下とすると、スキン層２５を確実に打ち抜いて発泡層２６を露出させることができた。 When the skin layer 2 was punched by appropriately changing the mold temperature, injection speed, core back speed, forward speed of the pin member 8, etc., the shear strength τf of the skin layer 25 was 13.8 N / mm 2 or more. 0N / mm 2 or less, compressive yield strength σc of the foam layer 26 is at 2.0 N / mm 2 or more 2.6 N / mm 2 or less, and the maximum shear load Qf max (v) foaming of the skin layer 25 When the maximum compressive yield load Cc max (v) of the layer 26 is smaller, if the forward speed of the pin member 8 is 15 mm / s or more and 19 mm / s or less, the skin layer 25 is surely punched to expose the foam layer 26. I was able to.

＜スキン層の薄肉化＞
以上から明らかなように、スキン層２５の最大せん断荷重Qf max(v)はスキン層２５の厚さｔfに比例する。従って、スキン層２５のピン部材８で打ち抜かれる部分のみをまわりよりも薄くすると、得られる発泡樹脂成形体２７の表面強度を損なうことなく、ピン部材８によるスキン層２５の打ち抜きが容易になる。 <Thinning of skin layer>
As is clear from the above, the maximum shear load Qf max (v) of the skin layer 25 is proportional to the thickness tf of the skin layer 25. Therefore, if only the portion of the skin layer 25 punched by the pin member 8 is made thinner than the surroundings, the skin layer 25 can be easily punched by the pin member 8 without impairing the surface strength of the obtained foamed resin molded body 27.

この薄肉化は、ピン部材８の先端面の熱伝導率を可動型本体７の成形面の熱伝導率よりも小さくすることで成すことができる。例えば、ピン部材８の先端面の熱伝導率を０．１Ｗ／ｍ・Ｋ以上０．５Ｗ／ｍ・Ｋ以下とし、可動型本体７の成形面の熱伝導率を１６Ｗ／ｍ・Ｋ以上２２０Ｗ／ｍ・Ｋ以下とすればよい。これにより、ピン部材８の先端面では発泡性樹脂の冷却速度が緩慢になり、該ピン部材８との接触によって形成されるスキン層は薄くなる。例えば、金型材料として熱伝導率６０．５Ｗ／ｍ・Ｋのクロム・モリブデン鋼を用い、ピン部材８の先端面に熱伝導率０．３Ｗ／ｍ・Ｋのポリイミド樹脂の被覆層を設けると、スキン層２５の厚さは、可動型本体７に接触する部分が０．３ｍｍ程度になり、ピン部材８に接触する部分が０．２ｍｍ程度になる。すなわち、ピン部材８に接触する部分のスキン層厚さはそのまわりの厚さの２／３程度になる。   This thinning can be achieved by making the thermal conductivity of the tip surface of the pin member 8 smaller than the thermal conductivity of the molding surface of the movable body 7. For example, the thermal conductivity of the tip surface of the pin member 8 is 0.1 W / m · K or more and 0.5 W / m · K or less, and the thermal conductivity of the molding surface of the movable mold body 7 is 16 W / m · K or more and 220 W. / M · K or less. As a result, the cooling rate of the foamable resin becomes slow at the tip surface of the pin member 8, and the skin layer formed by contact with the pin member 8 becomes thin. For example, when chromium / molybdenum steel having a thermal conductivity of 60.5 W / m · K is used as a mold material, and a polyimide resin coating layer having a thermal conductivity of 0.3 W / m · K is provided on the tip surface of the pin member 8. The thickness of the skin layer 25 is about 0.3 mm at the portion contacting the movable body 7 and about 0.2 mm at the portion contacting the pin member 8. That is, the thickness of the skin layer at the portion in contact with the pin member 8 is about 2/3 of the surrounding thickness.

上記金型材料としては、クロム・モリブデン鋼の他に、ステンレス鋼（例えば、ＳＵＳ３０４等のオーステナイト系ステンレス鋼）、アルミニウム合金等を採用することもでき、上記被覆層に関しては、ポリイミド等の合成樹脂に代えて無機酸化物（例えば、アルミナ、シリカ、ジルコニア等）を採用することもできる。   As the mold material, in addition to chromium / molybdenum steel, stainless steel (for example, austenitic stainless steel such as SUS304), aluminum alloy, or the like can be adopted. For the coating layer, a synthetic resin such as polyimide is used. Instead of inorganic oxides (for example, alumina, silica, zirconia, etc.) may be employed.

また、ピン部材８の先端面だけでなく、このピン部材８の先端面を囲む成形面の環状部分を含めて低熱伝導率の被覆層を設けるようにしてもよい。   Moreover, you may make it provide not only the front end surface of the pin member 8, but the coating layer of low heat conductivity including the annular part of the molding surface surrounding the front end surface of this pin member 8.

なお、上記実施形態では可動型５にピン部材８を設けたが、固定型４にピン部材を設けてもよい。   In the above embodiment, the pin member 8 is provided on the movable mold 5, but the pin member may be provided on the fixed mold 4.

また、ピン部材８の断面形状は、円形に限る必要はなく、三角形、その他の多角形、或いは瓢箪型など適宜の形状にすることができる。   Moreover, the cross-sectional shape of the pin member 8 does not need to be limited to a circle, and may be an appropriate shape such as a triangle, other polygons, or a bowl shape.

１ 成形型
２ 射出装置
３ キャビティ
４ 固定型
５ 可動型
６ スプルー
７ 可動型本体
８ ピン部材
２５ スキン層
２６ 発泡層
２７ 発泡樹脂成形体
２８ 打抜き孔 DESCRIPTION OF SYMBOLS 1 Mold 2 Injection apparatus 3 Cavity 4 Fixed mold 5 Movable mold 6 Sprue 7 Movable mold main body 8 Pin member 25 Skin layer 26 Foam layer 27 Foamed resin molding 28 Punching hole

Claims (2)

発泡層がスキン層で覆われ、且つそのスキン層の一部が発泡層内に打ち抜かれ当該打抜き孔の内周面に発泡層が露出してなる発泡樹脂成形体の製造方法であって、
上記発泡樹脂成形体成形用のキャビティを形成する固定型及び可動型の少なくとも一方は型本体とピン部材とを備え、該ピン部材はその先端面が当該型本体の成形面と共に上記キャビティを形成しており、
上記ピン部材の先端面の熱伝導率、又は上記ピン部材の先端面及び該ピン部材の先端面を囲む上記成形面の環状部分の熱伝導率が、そのまわりの上記成形面の熱伝導率よりも低く、
原料樹脂に発泡剤を含ませてなる溶融状態の発泡性樹脂を上記キャビティに充填することにより、上記発泡層がスキン層で覆われてなる発泡樹脂成形体をそのキャビティ内に成形した後、
上記ピン部材を上記キャビティ内に突き入れることにより、上記スキン層を打ち抜いて当該打抜き孔の内周面に上記発泡層を露出させることを特徴とする発泡樹脂成形体の製造方法。 The foamed layer is covered with a skin layer, and a part of the skin layer is punched into the foamed layer, and the foamed layer is exposed on the inner peripheral surface of the punched hole.
At least one of a fixed mold and a movable mold that form a cavity for molding the foamed resin molded body includes a mold body and a pin member, and the tip end surface of the pin member forms the cavity together with a molding surface of the mold body. And
The thermal conductivity of the tip surface of the pin member, or the thermal conductivity of the annular surface portion of the molding surface surrounding the tip surface of the pin member and the tip surface of the pin member is based on the thermal conductivity of the molding surface around it. Too low,
After filling the cavity with a foamable resin in a molten state containing a foaming agent in the raw resin, the foamed resin molded body in which the foamed layer is covered with a skin layer is molded into the cavity.
A method for producing a foamed resin molded article, wherein the skin layer is punched by exposing the pin member into the cavity to expose the foam layer on the inner peripheral surface of the punch hole. 請求項１において、
上記原料樹脂はポリプロピレンであり、
上記ピン部材を上記キャビティ内に突き入れる速度を１５ｍｍ／ｓ以上１９ｍｍ／ｓ以下とし、
上記キャビティ内に、上記速度でのスキン層のせん断強さτｆが１３．８Ｎ／ｍｍ２以上１８．０Ｎ／ｍｍ２以下、発泡層の圧縮降伏強さσｃが２．０Ｎ／ｍｍ２以上２．６Ｎ／ｍｍ２以下であり且つ上記スキン層の最大せん断荷重が上記発泡層の最大圧縮降伏荷重よりも小さい発泡樹脂成形体を成形することを特徴とする発泡樹脂成形体の製造方法。 In claim 1 ,
The raw material resin is polypropylene,
The speed at which the pin member is pushed into the cavity is 15 mm / s or more and 19 mm / s or less,
In the cavity, shear strength τf of the skin layer at the rate of 13.8N / mm 2 or more 18.0N / mm 2 or less, compressive yield strength σc of the foam layer is 2.0 N / mm 2 or more 2. method for producing a foamed resin molded maximum shear load of 6N / mm 2 or less and and the skin layer has a smaller resin foam body formed shape to Rukoto than the maximum compressive yield load of the foamed layer.
JP2011248724A 2011-11-14 2011-11-14 Method for producing foamed resin molded body Expired - Fee Related JP5803592B2 (en)

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