JP4127430B2 - Manufacturing method of automotive exterior board - Google Patents

Description

自動車用外装板成形品の外面に形成した粗面の表面粗さおよび使用する金型のキャビティの微小凹凸の表面粗さは０．９〜９．０μｍの範囲以内とするが、この表面粗さとは、キャビティの表面を触針電気式粗さ測定器で測定した最大高さを基本にした粗さ（ＪＩＳ−Ｂ−０６０１）であり、詳しくは粗面あるいは微小凹凸の山部（凸）の最大高さと谷部（凹）の最大深さの和により求めたものである。
【００４９】
この表面粗さは、特にブロー成形品の場合、表面が緩やかな曲線であることが多いため断面曲線による最大高さＲｍａｘ（ＪＩＳ−Ｂ−０６０１）ではなく粗さ曲線（ＪＩＳ−Ｂ−０６０１）から求められる山部（凸）の最大高さと谷部（凹）の最大深さの和により求めたものを採用した。このときの粗さ曲線カットオフ値は０．８ｍｍとした。
【００５０】
また、自動車用外装板成形品の外面に形成した粗面の平均山間隔および使用する金型のキャビティの微小凹凸の平均山間隔は１０〜１５０μｍの範囲以内とするが、この平均山間隔とは、キャビティの表面を触針電気式粗さ測定器で測定した山部間の平均間隔であり、ここでは測定表面を任意に５カ所用意し各４ｍｍ幅で測定した。
【００５１】
平均山間隔Ｓｍは破断面曲線（ＪＩＳ−Ｂ−０６０１）から測定長さ分だけ抜き取った部分の平行線を横切って山から谷へ向かう点から次の山から谷へ向かう横断面までの間隔の平均値である。このときの粗さに対する縦方向の倍率は２００００倍または１００００倍とし、横方向の倍率は５０倍とした。
【００５２】
表面粗さが０．９〜９．０μｍの範囲以内でかつ平均山間隔が１０〜１５０μｍの範囲以内の微小凹凸をキャビティに形成するには、粒度が１５０〜１０００のサンドを吹きつけること、つまりサンドブラストが好適である。
【００５３】
また、自動車用外装板成形品の外面に対する塗膜の塗布は、公知の塗装方法と同様に塗料をエアスプレーガンにて吹き付けることにより１５〜１５０μｍの塗膜を形成する。
【００５４】
【実施例】
本発明の効果を確認するための実験を行なったので、その結果について説明する。
【００５５】
実験例としては、スクリュ径９０ｍｍの押出機を備えたブロー成形機を用い、図３に示すような、長さＬが１２００ｍｍ、幅Ｄが１８０ｍｍ、高さＨが９０ｍｍであって平均肉厚が３ｍｍのスポイラー成形品１０をブロー成形したのち、スポイラー成形品１０の外面に５０μｍの塗膜を塗布したスポイラーを製造した。
【００５６】
実験例１〜実験例７は、サンドブラストによってキャビティの表面粗さを５．０μｍとし平均山間隔が２５μｍの微小凹凸を有する金型を用い、無機フィラーとしてタルクを１０重量％配合したポリプロピレン（日本ポリケム株式会社製、ＥＣ−９、Ａ＝１１５℃、Ｂ＝１６２℃）のパリスンを２２０℃にて押し出し、キャビティの表面温度を変化させることにより、各サンプルを製造した。
【００５７】
実験例８は、キャビティの表面粗さを５．０μｍとし平均山間隔が２５μｍの微小凹凸を有する金型を用い、キャビティの表面温度は一定にし、無機フィラーの含有量を変化させてサンプル１〜９を製造した。
【００５８】
実験例９は、キャビティの表面粗さを２．０μｍとし平均山間隔が１０μｍの微小凹凸を有する金型を用いた以外は実験例５と同様にサンプル１〜９を製造した。
【００５９】
実験例１０は、キャビティの表面粗さを１．０μｍとし平均山間隔が１０μｍの微小凹凸を有する金型を用いた以外は実験例５と同様にサンプル１〜９を製造した。
【００６０】
実験例１１は、キャビティの表面粗さを０．９μｍとし平均山間隔が１０μｍの微小凹凸を有する金型を用いた以外は実験例５と同様にサンプル１〜９を製造した。
【００６１】
実験例１２は、キャビティの表面粗さを０．８μｍとし平均山間隔が１０μｍの微小凹凸を有する金型を用いた以外は実験例５と同様にサンプル１〜９を製造した。
【００６２】
実験例１３は、キャビティの表面粗さを９．０μｍとし平均山間隔が３０μｍの微小凹凸を有する金型を用いた以外は実験例５と同様にサンプル１〜９を製造した。
【００６３】
実験例１４は、キャビティの表面粗さを１０μｍとし平均山間隔が３０μｍの微小凹凸を有する金型を用いた以外は実験例５と同様にサンプル１〜９を製造した。
【００６４】
実験例１５は、キャビティの表面粗さを３．０μｍとし平均山間隔が１０μｍの微小凹凸を有する金型を用いた以外は実験例５と同様にサンプル１〜９を製造した。
【００６５】
実験例１６は、キャビティの表面粗さを３．０μｍとし平均山間隔が９μｍの微小凹凸を有する金型を用いた以外は実験例５と同様にサンプル１〜９を製造した。
【００６６】
実験例１７は、キャビティの表面粗さを５．０μｍとし平均山間隔が１５０μｍの微小凹凸を有する金型を用いた以外は実験例５と同様にサンプル１〜９を製造した。
【００６７】
実験例１８は、キャビティの表面粗さを５．０μｍとし平均山間隔が１６０μｍの微小凹凸を有する金型を用いた以外は実験例５と同様にサンプル１〜９を製造した。
【００６８】
実験例１９は、サンドブラストによってキャビティの表面粗さを５．０μｍとし平均山間隔が２５μｍの微小凹凸を有する金型を用い、ポリプロピレン／高密度ポリエチレンブレンド樹脂のパリスンを２１０℃で押し出し、キャビティの表面温度を変化させることにより１〜９のサンプルを製造した。ここで、ポリプロピレン／高密度ポリエチレン樹脂は、ポリプロピレン（日本ポリケム株式会社製、ＥＣ−９、Ａ＝１１５℃、Ｂ＝１６２℃）と高密度ポリエチレン（旭化成工業株式会社製、Ｂ−９７０、Ａ＝１２１℃、Ｂ＝１３０℃）とを７０：３０の比率にてブレンドしたものであり、このブレンド樹脂の各ピーク温度は、Ａ１１６．８℃であり、Ｂ＝１５２．４℃である。
【００６９】
実験例２０は、キャビティの表面温度を一定にし、無機フィラーの含有量を変化させる以外は実験例１９と同様にサンプル１〜９を製造した。
【００７０】
実験例２１は、キャビティの表面粗さを２．０μｍとし平均山間隔が１０μｍの微小凹凸を有する金型を用いた以外は実験例１９と同様にサンプル１〜９を製造した。
【００７１】
実験例２２は、キャビティの表面粗さを１．０μｍとし平均山間隔が１０μｍの微小凹凸を有する金型を用いた以外は実験例１９と同様にサンプル１〜９を製造した。
【００７２】
実験例２３は、キャビティの表面粗さを０．９μｍとし平均山間隔が１０μｍの微小凹凸を有する金型を用いた以外は実験例１９と同様にサンプル１〜９を製造した。
【００７３】
実験例２４は、キャビティの表面粗さを０．８μｍとし平均山間隔が１０μｍの微小凹凸を有する金型を用いた以外は実験例１９と同様にサンプル１〜９を製造した。
【００７４】
実験例２５は、キャビティの表面粗さを９．０μｍとし平均山間隔が３０μｍの微小凹凸を有する金型を用いた以外は実験例１９と同様にサンプル１〜９を製造した。
【００７５】
実験例２６は、キャビティの表面粗さを１０μｍとし平均山間隔が３０μｍの微小凹凸を有する金型を用いた以外は実験例１９と同様にサンプル１〜９を製造した。
【００７６】
実験例２７は、キャビティの表面粗さを３．０μｍとし平均山間隔が９μｍの微小凹凸を有する金型を用いた以外は実験例１９と同様にサンプル１〜９を製造した。
【００７７】
実験例２８は、キャビティの表面粗さを３．０μｍとし平均山間隔が１０μｍの微小凹凸を有する金型を用いた以外は実験例１９と同様にサンプル１〜９を製造した。
【００７８】
実験例２９は、キャビティの表面粗さを５．０μｍとし平均山間隔が１５０μｍの微小凹凸を有する金型を用いた以外は実験例１９と同様にサンプル１〜９を製造した。
【００７９】
実験例３０は、キャビティの表面粗さを５．０μｍとし平均山間隔が１６０μｍの微小凹凸を有する金型を用いた以外は実験例１９と同様にサンプル１〜９を製造した。
【００８０】
実験例１〜実験例３０の評価を表２〜表３１に示す。
【００８１】
表２〜表３１における評価基準は次のとおりである。
【００８２】
表中、Ｒｔは成形品の表面粗さを示し、単位はμｍであり、Ｓｍは成形品の粗面の平均山間隔を示し、単位はμｍである。変形、肌荒れ、エアーマーク、ダイライン、ブツは、ブロー成形後でかつ塗装前の成形品の外観を目視により判断した。
【００８３】
変形
○：見られない。
△：若干見られるが、問題ないと判断できる。
×：見られる。
【００８４】
肌荒れ
○：表面にさめ肌状の凹凸がなく均一である。
△：若干、さめ肌状のものが見られる。
×：表面に著しいさめ肌状の凹凸がある。
【００８５】
エアーマーク
○：発生していない。
△：ほとんど発生していない。
×：発生している。
【００８６】
ダイライン
○：発生していない。
△：ほとんど発生していない。
×：発生している。
【００８７】
ブツ
○：発生していない。
△：ほとんど発生していない。
×：発生している。
【００８８】
塗面の外観
○：ゆず肌の発生が見られなかった。
△：わずかにゆず肌の発生が見られた。
×：ゆず肌が発生した。
【００８９】
【表２】

【００９０】
【表３】

【００９１】
【表４】

【００９２】
【表５】

【００９３】
【表６】

【００９４】
【表７】

【００９５】
【表８】

表２〜表８より、パリスンの密着中のキャビティの表面温度Ｙ℃が１７５℃になると成形サイクルが３００秒に上がることが分かる。しかも、表７より、自動車用外装板成形品を取り出す際の型開き開始時点におけるキャビティの表面温度Ｚ℃が、１００℃を越えると成形品の変形が発生し、成形品自体の塗面の外観も落ちることが分かる。
【００９６】
【表９】

表９にて、フィラーの含有量が４０重量％を越えるとパリスン自体の伸びが悪くなり、表面に肌荒れが発生し、その結果成形品の塗面が悪化した。フィラーが５０重量％となったサンプル９ではさらにパリスンの伸びが悪いためにブロー成形時に成形品に孔があき成形することができなかった。
【００９７】
これらによりフィラー含有量が３５重量％を越えるとパリスンの伸びは極端に悪くなり、成形品の表面が悪化し、その結果塗装面が悪化することが分かる。
【００９８】
逆に、フィラーの含有量が、３重量％未満であるとパーティングライン部分をサンディング処理に要する時間が４０分近くと長くなることがわかる。
【００９９】
【表１０】

【０１００】
【表１１】

【０１０１】
【表１２】

【０１０２】
【表１３】

【０１０３】
【表１４】

【０１０４】
【表１５】

表１０〜表１５より、キャビティの微小凹凸の表面粗さＲｔは０．９〜９．０μｍであることが必要であることが分かる。
【０１０５】
表１３によるものは、塗面の外観が極端に悪いことが分かるし、表１５も同様に比べて悪い。これよりキャビティのＲｔは、０．９〜９．０μｍであることが必要であることが分かる。
【０１０６】
【表１６】

【０１０７】
【表１７】

【０１０８】
【表１８】

【０１０９】
【表１９】

表１６〜表１９より、キャビティの微小凹凸の平均山間隔Ｓｍは１０〜１５０μｍであることが必要であることが分かる。
【０１１０】
表１７によるものは、塗面の外観が極端に悪いことが分かるし、表１９も同様に比べて悪い。これよりキャビティの平均山間隔Ｓｍは１０〜１５０μｍであることが必要であることが分かる。
【０１１１】
表２〜表１９より、自動車用外装品成形品の表面は、表面粗さＲｔは０．９〜９．０μｍ、平均山間隔Ｓｍは１０〜１５０μｍであることが必要であることが分かる。
【０１１２】
【表２０】

【０１１３】
【表２１】

表２１にて、フィラーの含有量が４０重量％を越えるとパリスン自体の伸びが悪くなり、表面に肌荒れが発生し、その結果成形品の塗面が悪化した。フィラーが５０重量％となったサンプル９ではさらにパリスンの伸びが悪いためにブロー成形時に成形品に孔があき成形することができなかった。
【０１１４】
これらによりフィラー含有量が３５重量％を越えるとパリスンの伸びは極端に悪くなり、成形品の表面が悪化し、その結果塗装面が悪化することが分かる。
【０１１５】
逆に、フィラーの含有量が、３重量％未満であるとパーティングライン部分をサンディング処理に要する時間が５０分近くと長くなることがわかる。
【０１１６】
【表２２】

【０１１７】
【表２３】

【０１１８】
【表２４】

【０１１９】
【表２５】

【０１２０】
【表２６】

【０１２１】
【表２７】

表２２〜表２７より、パリスンの密着中のキャビティの表面温度Ｙ℃が１６５℃になると成形サイクルが３００秒に上がることが分かる。
【０１２２】
表２２〜表２７より、キャビティの微小凹凸の表面粗さＲｔは０．９〜９．０μｍであることが必要であることが分かる。
【０１２３】
表２５によるものは、塗面の外観が極端に悪いことが分かるし、表２６も同様に他に比べて悪い。これによりキャビティのＲｔは、０．９〜９．０μｍであることが必要であることが分かる。
【０１２４】
【表２８】

【０１２５】
【表２９】

【０１２６】
【表３０】

【０１２７】
【表３１】

表２８〜表３１より、キャビティの微小凹凸の平均山間隔Ｓｍは１０〜１５０μｍであることが必要であることが分かる。
【０１２８】
表２８によるものは、塗面の外観が極端に悪いことが分かるし、表３１も同様に比べて悪い。これよりキャビティの平均山間隔Ｓｍは１０〜１５０μｍであることが必要であることが分かる。
【０１２９】
表２０〜表３１より、自動車用外装品成形品の表面は、表面粗さＲｔは０．９〜９．０μｍ、平均山間隔Ｓｍは１０〜１５０μｍであることが必要であることが分かる。
【０１３０】
【発明の効果】
本発明は上述のとおり構成されているので、次に記載するような効果を奏する。
【０１３１】
ブロー成形した自動用外装板成形品の外面に斑点や線状痕さらにはエアーマークが発生するおそれがなく、前記自動車用外装板成形品の外面を研磨や水研ぎすることなく直接塗膜を塗布するだけで、剛性等の機械的強度に優れかつ外観良好な自動車用外装板を製造することができる。
【図面の簡単な説明】
【図１】型開きした金型間にパリスンを押し出した状態を示す模式断面図である。
【図２】ブロー成形された自動車用外装板成形品を金型中で冷却したのち、金型を型開きした状態を示す模式断面図である。
【図３】ブロー成形されたスポイラー成形品を示す模式斜視図である。
【符号の説明】
１ 自動車用外装板成形品
２ 押出ヘッド
３ パリスン
４，５ 金型
４ａ，５ａ キャビティ
６，７ 加熱手段
１０ スポイラー成形品[0001]
BACKGROUND OF THE INVENTION
  The present invention provides an automotive exterior board having a good appearance.ofIt relates to a manufacturing method.
[0002]
[Prior art]
A conventional method for producing a hollow molded article having a good appearance will be described.
[0003]
(A) A split mold having a mirror-finished cavity surface is used, and the tensile elastic modulus is 2000 kg / cm between the opened molds.² When a Paris made of an amorphous resin having a temperature of 75 ° C. or higher is placed, the mold is closed, and then, when the gas is blown into the Paris to be brought into close contact with the cavity, the cavity temperature Y₀ The tensile modulus of the amorphous resin is 2000 kg / cm.² For the temperature X
Y₀ = (0.96X₀ -37) to (0.96X₀ +3)
It is set so that it is within the range of (1), and is in close contact (Japanese Patent Publication No. 6-22875).
[0004]
(B) In thermoplastic molding or hollow molding of thermoplastic resin, the surface of the molded product is glossed by selectively and instantaneously heating the mold surface above the thermal deformation temperature of the resin by high-frequency induction heating. (Japanese Patent Publication No. 1-27849).
[0005]
(C) A melted parison made of a crystalline resin and having a surface on which a number of fine irregularities having a depth of 2 to 100 μm are formed on a mirror surface having a roughness of 0.5 S or less heated to a temperature higher than the crystallization temperature of the resin. Blow molding with a finished mold (Japanese Patent Publication No. 2-40498).
[0006]
[Problems to be solved by the invention]
Among the above-mentioned conventional techniques, (a) is an automotive exterior panel that is unavoidably caused by spots and linear marks on the outer surface of a hollow molded article made of amorphous resin, and whose appearance is strictly required. Must be applied to the outer surface of the blow-molded amorphous resin hollow molded product after polishing or water-polishing the outer surface to remove spots and line marks. . For this reason, there existed a problem that the number of processes increased and the manufacturing cost was raised.
[0007]
Further, (b) has a problem in that it is necessary to provide a special molding apparatus equipped with a heating device for high-frequency induction heating of the mold, resulting in high costs.
[0008]
Furthermore, (c) has melt fractures generated in Paris in order to form a large number of fine irregularities with a depth of 2 to 100 μm on the surface of Paris, but this melt fracture is difficult to control and is mass-produced. Has the problem of being unsuitable.
[0009]
  The present invention has been made in view of the above-described problems of the prior art, and a coating film is applied to an outer surface without performing polishing or water-polishing of the outer surface of a blow molded automobile exterior plate molded product. The exterior panel for automobiles that can provide an exterior panel for automobiles that is excellent in mechanical strength such as rigidity and that has a good appearance without distorted skin on the painted surface.ofThe object is to realize a manufacturing method.
[0010]
[Means for Solving the Problems]
  In order to achieve the above object, the automotive exterior panel of the present inventionManufacturing methodIsIn a method for manufacturing an automotive exterior plate, in which a hollow automotive exterior plate molded product is blow-molded and then a 15 to 150 μm coating film is applied to the outer surface of the automotive exterior plate molded product, The blow molding was opened using a mold having cavities with minute irregularities having a surface roughness within a range of 0.9 to 9.0 μm and an average crest interval of 10 to 150 μm. Between the moldsFlexural modulus at 23 ° C. is 9000 kg / cm²The above crystalline resinAnd then closing the mold, and then introducing a pressurized fluid into the parison to bring it into close contact with the cavity.
A <Y <1.07B
Here, A: flexural modulus at 23 ° C. is 9000 kg / cm ² Crystallization peak temperature (° C) in DSC curve of the above crystalline resin
B: Flexural modulus at 23 ° C. is 9000 kg / cm ² Melting peak temperature (° C) in DSC curve of the above crystalline resin
Raise the temperature to meetIt is characterized by this.
[0014]
Moreover, the manufacturing method of the 2nd exterior plate | board for motor vehicles of this invention blow-molds the hollow automotive exterior board molded article, Then, a 15-150 micrometer coating film is apply | coated to the outer surface of the said automotive exterior board molded product. In the method for manufacturing an automotive exterior plate, the blow molding of the automotive exterior plate molded product has a surface roughness within a range of 0.9 to 9.0 μm and an average crest interval within a range of 10 to 150 μm. Using a mold having a cavity with minute irregularities, the bending elastic modulus at 23 ° C. is 9000 kg / cm between the molds opened.² After the Paris made of the above crystalline resin is arranged, the mold closing is started, and the surface temperature Y ° C. of the cavity immediately before the completion of the mold closing is expressed by the following formula:
A <Y <1.07B
Here, A: flexural modulus at 23 ° C. is 9000 kg / cm² Crystallization peak temperature (° C) in DSC curve of the above crystalline resin
B: Flexural modulus at 23 ° C. is 9000 kg / cm² Melting peak temperature (° C) in DSC curve of the above crystalline resin
The mold is closed by raising the temperature so as to satisfy the condition, and then a pressurized fluid is introduced into the parison to closely contact the cavity.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
In the above-described conventional technology, the spots and linear marks generated on the outer surface of the blow molded resin hollow molded product are caused by rough skin, die lines, and irregularities generated on the outer surface of Paris.
[0016]
By the way, rough skin is caused by the flow of the molten resin passing through the extrusion head when extruding the Paris, and is irregular irregularities of about 2 μm or more generated on the outer surface of the Paris.
[0017]
The die line is caused by a joining portion in the flow direction of the molten resin in the extrusion head when extruding the Paris, and is a streak-like depression having a depth of 2 to 500 μm generated on the outer surface of the Paris.
[0018]
The blister is caused by unmelted granular material or carbide of the resin, and is a 5-1000 μm protrusion or recess appearing on the outer surface of Paris.
[0019]
Therefore, as a result of repeating many experiments, the rough surface generated on the outer surface of these Parisons, the spots and linear marks generated on the outer surface of the crystalline resin molded product due to the die line, and the like are molds having a mirror cavity. Rather than using a mold having a predetermined surface roughness and fine irregularities with an average crest spacing in the cavity, and the knowledge that it can be suppressed by setting the surface temperature of the cavity to a predetermined temperature and performing blow molding Obtained.
[0020]
The above findings were surprising from conventional common sense. This knowledge is more important than the following two points.
[0021]
For example, rough skin generated on the outer surface of Paris, die lines, and spots, and line marks generated on the outer surface of a crystalline resin molded product are removed by raising the surface temperature of the cavity to a predetermined temperature. It has been found that it can be done. By raising the temperature of the surface of the Paris to a predetermined temperature, it is possible to erase the spots and line marks formed on the surface during the extrusion of the Paris. This is like giving a kind of heat treatment to Paris by the surface temperature of the cavity. This makes it possible to remove spots, line marks, and the like that could not be removed by conventional techniques.
[0022]
However, when the surface temperature of the cavity is raised to a predetermined temperature, the crystalline resin molded product can surely remove rough skin generated on the surface of the parison, spots and line marks generated by die lines and bumps, etc. As a result of this treatment, it was found that a crater-like material called an air mark was newly generated on the surface. If the air mark is painted on it as it is, the air mark is reflected on the painted surface, so in the end it must be removed by polishing or water sharpening as before. End up. It has also been found that the air mark tends to occur in a complicated shape portion as the shape of the crystalline resin molded product becomes more complicated.
[0023]
Therefore, another finding is that the air mark is formed on the surface of the cavity when minute irregularities having a surface roughness within a range of 0.9 to 9 μm and an average crest interval of 10 to 150 μm are formed. Not only can this be prevented, but such micro unevenness means that even if the surface roughness of the cavity surface is larger than the surface roughness of the Paris, good results can be obtained that do not require polishing or water sharpening. That is, when the fine irregularities are suitable for the coating film when the specific irregularities, in particular, the average crest interval is within the range of 10 to 150 μm, when coated on this crystalline resin molded product, The coating film enters the inside of the micro unevenness by a kind of capillary phenomenon, and as a result, a good painted surface is obtained. When the inventors actually measured the surface of Paris at the time of extrusion, the surface roughness of the surface of Paris was 3 μm and the average crest distance was 539 μm. Even if the surface roughness of the parison is small to a certain degree, the average crest spacing is large, so if the surface of the molded product is left with such a parison surface condition, the crests and troughs are painted. Since it cannot be filled with a film and the unevenness appears on the painted surface, it is expected that the painted surface such as the skin will be defective.
[0024]
In the present invention, as described above, rough skin generated on the outer surface of the Paris, die lines, spots and linear marks generated on the outer surface of the crystalline resin molded product by using a die having a mirror cavity are used. Rather, it is based on the knowledge that it can be suppressed by using a mold having a predetermined surface roughness and minute irregularities with an average peak spacing on the surface of the cavity, and setting the surface temperature of the cavity to a predetermined temperature and performing blow molding. It is what was done.
[0025]
Judging from these, the flexural modulus at 23 ° C. is 9000 kg / cm.² The exterior plate for automobiles, in which a coating film of 15 to 150 μm is applied to the outer surface of a hollow automotive exterior plate molded product obtained by blow molding the above crystalline resin, has a specific rough surface, that is, a surface roughness. If it is within the range of 0.9 to 9.0 μm and the average crest interval is within the range of 10 to 150 μm, the coated surface of the surface can obtain a beautiful appearance without any distorted skin and is required as an exterior panel for automobiles. It has been found that it has a mechanical strength such as rigidity.
[0026]
Also, the flexural modulus at 23 ° C. is 9000 kg / cm.² By blending the above crystalline resin with an inorganic filler within the range of 3 to 35% by weight, the parting line generated in blow molded automotive exterior panel molded products is removed by normal processing such as sanding. It becomes easy to do. If the blending ratio of the inorganic filler is less than 3% by weight, the surface of the parting line is removed by sanding or the like, so that it cannot be finished to a predetermined surface roughness. On the other hand, when the blend ratio of the inorganic filler is more than 35% by weight, it becomes too hard, leading to a decrease in the skin of the coated surface, a decrease in moldability, and a decrease in product physical properties.
[0027]
Then, 1st Embodiment of the manufacturing method of the exterior plate for motor vehicles of this invention is described.
[0028]
(1) As shown in FIG. 1, the split type having minute irregularities in which the surface roughness of the cavities 4a and 5a is within the range of 0.9 to 9.0 μm and the average crest interval is within the range of 10 to 150 μm. Using the molds 4 and 5, the bending elastic modulus at 23 ° C. is 9000 kg / cm between the opened molds 4 and 5.² The Paris 3 made of the above crystalline resin is extruded from the extrusion head 2 and arranged.
[0029]
(2) After the above (1), the molds 4 and 5 are closed to hold the Paris 3, and then the pressurized fluid in the Paris 3 is about 7 kg / cm with a blow needle (not shown).² Is introduced into the cavity 4a, 5a so as to be in close contact with the cavity 4a, 5a, and blow molded into a hollow automobile exterior plate molded product 1.
[0030]
In this step, the surfaces of the cavities 4a and 5a in which the parison 3 is in close contact with the cavities 4a and 5a by the heating means 6 and 7 using heating medium such as heated water, steam, and oil provided in the molds 4 and 5 The temperature Y ° C is
A <Y <1.07B
Here, A: flexural modulus at 23 ° C. is 9000 kg / cm² Crystallization peak temperature (° C) in the DSC curve (see JISK7121) of the above crystalline resin
B: Flexural modulus at 23 ° C. is 9000 kg / cm² Melting peak temperature (° C) in the DSC curve (see JISK7121) of the above crystalline resin
The temperature is raised to satisfy.
[0031]
{Circle around (3)} After the step {circle around (2)}, the automobile exterior plate molded product 1 is cooled in the molds 4 and 5, and then the mold is opened and taken out as shown in FIG. 2 to remove excess burrs.
[0032]
When the surface temperature Z ° C. of the cavities 4a and 5a is set to Z ≦ A-15 when the mold is opened and the car exterior plate molded article 1 is taken out, the appearance without deformation after mold release is beautiful. An automotive exterior plate molded product 1 is obtained.
[0033]
(4) After the above step (3), the parting line portion is removed by sanding treatment, and then a 15 to 150 μm coating is applied to the outer surface of the automotive exterior plate molded product 1 to produce an automotive exterior plate. To do.
[0034]
Next, a second embodiment of the method for manufacturing an automobile exterior plate of the present invention will be described.
[0035]
(1) As shown in FIG. 1, the split type having minute irregularities in which the surface roughness of the cavities 4a and 5a is within the range of 0.9 to 9.0 μm and the average crest interval is within the range of 10 to 150 μm. Using the molds 4 and 5, the bending elastic modulus at 23 ° C. is 9000 kg / cm between the opened molds 4 and 5.² The Paris 3 made of the above crystalline resin is extruded from the extrusion head 2 and arranged.
[0036]
(2) After the above (1), mold closing of the molds 4 and 5 is started, the molds are heated by the heating means 6 and 7, and the cavities 4a and 4a of the molds 4 and 5 immediately before completion of the mold closing are obtained. The surface temperature Y ° C of 5a is
A <Y <1.07B
Here, A: flexural modulus at 23 ° C. is 9000 kg / cm² Crystallization peak temperature (° C) in the DSC curve (see JISK7121) of the above crystalline resin
B: Flexural modulus at 23 ° C. is 9000 kg / cm² Melting peak temperature (° C) in the DSC curve (see JISK7121) of the above crystalline resin
The temperature is raised to satisfy.
[0037]
(3) After the above (2), the mold closing is completed, and then about 7 kg / cm, which is a pressurized fluid, in the parison 3 with a blowing needle (not shown)² Is introduced into the cavity 4a, 5a so as to be in close contact with the cavity 4a, 5a, and blow molded into a hollow automobile exterior plate molded product 1.
[0038]
(4) After the above step (3), the automotive exterior plate molded product 1 is cooled in the molds 4 and 5, and then the mold is opened and removed as shown in FIG. 2 to remove excess burrs.
[0039]
If the surface temperature Z ° C. of the cavities 4a and 5a is set to Z ≦ A-15 when the mold is opened and the car exterior plate molded article 1 is taken out, the appearance without deformation after mold release is beautiful. An automotive exterior plate molded product 1 is obtained.
[0040]
(5) After the above (4), the parting line portion is removed by sanding treatment, and then a coating film of 15 to 150 μm is applied to the outer surface of the automotive exterior plate molding 1 to produce an automotive exterior plate. .
[0041]
In the present invention, the automobile exterior plate refers to a spoiler, a bumper, a trunk lid, a side molding, a fender, a bonnet, and the like that are strictly required to have a so-called good appearance with a clean surface gloss and color tone.
[0042]
The bending elastic modulus at 23 ° C. in the present invention is shown in JISK7171.
[0043]
Flexural modulus at 23 ° C. is 9000 kg / cm² The above crystalline resin can satisfy the mechanical strength such as rigidity required for an automobile exterior plate. For example, polypropylene, high density polyethylene, polyamide (6 nylon, etc.), a single resin of polybutylene terephthalate, A blend (alloy) resin with an amorphous resin containing 30% by weight or more of these crystalline resins, a blend (alloy) resin of these crystalline resins, and the like. Examples of the blend (alloy) resin with the amorphous resin include polyamide / modified polyphenylene ether resin and polypropylene / polystyrene resin. Moreover, as a blend (alloy) resin of crystalline resins, a polypropylene / polyethylene resin is mentioned.
[0044]
The crystallization peak temperature in the present invention is the crystallization peak temperature in the DSC curve defined in JISK7121, and the melting peak temperature is the melting peak temperature in the DSC curve defined in JISK7121. Here, in the case of a blend (alloy) resin with an amorphous resin, the crystallization peak temperature and the melting peak temperature of the crystalline resin contained therein are set as the respective temperatures of the blend (alloy) resin. In the case of a blend (alloy) resin of crystalline resins, the temperature obtained from the arithmetic average according to the blending ratio of the temperature of each of the crystalline resins contained can be treated as the current temperature. found.
[0045]
For example, the blend ratio of the crystalline resin (a) is a% and the melting peak temperature is t₁ The melting peak temperature of the crystalline resin (b) is t₂ The melting peak temperature B of the blend resin is
B = (a / 100) t₁ + (1-a / 100) t₂
It becomes. However, when the melting peak temperatures of the two types of crystalline resins (a) and crystalline resin (b) are close to each other and the respective DSC curve peaks do not appear clearly, the peak of the DSC curve peak is regarded as the blend product. Melting peak temperature.
[0046]
Similarly, the crystallization peak temperature can also be determined by the above method.
[0047]
Table 1 shows the temperatures of typical crystalline resins used in the present invention.
[0048]
[Table 1]

The surface roughness of the rough surface formed on the outer surface of the molded product for automobile exterior plates and the surface roughness of the micro unevenness of the cavity of the mold used are within the range of 0.9 to 9.0 μm. Is the roughness (JIS-B-0601) based on the maximum height of the cavity surface measured with a stylus electric roughness measuring instrument. It is obtained from the sum of the maximum height and the maximum depth of the valley (concave).
[0049]
This surface roughness is a curved curve (JIS-B-0601) rather than the maximum height Rmax (JIS-B-0601) due to the cross-sectional curve because the surface is often a gentle curve, particularly in the case of blow molded products. What was calculated | required by the sum of the maximum height of a peak (convex) and the maximum depth of a trough (concave) calculated | required from this was employ | adopted. The roughness curve cutoff value at this time was 0.8 mm.
[0050]
In addition, the average crest of the rough surface formed on the outer surface of the automobile exterior plate molded product and the average crevice of the minute irregularities of the mold cavity to be used are within the range of 10 to 150 μm. The average distance between the peaks measured on the surface of the cavity with a stylus electric roughness measuring device. Here, five measurement surfaces were arbitrarily prepared and measured at a width of 4 mm each.
[0051]
The average peak interval Sm is the interval from the point going from the peak to the valley across the parallel line of the part extracted from the fracture surface curve (JIS-B-0601) by the measured length to the cross-section going from the next peak to the valley. Average value. The vertical magnification with respect to the roughness at this time was 20000 times or 10,000 times, and the horizontal magnification was 50 times.
[0052]
In order to form minute irregularities with a surface roughness within a range of 0.9 to 9.0 μm and an average peak interval within a range of 10 to 150 μm, a sand having a particle size of 150 to 1000 is blown, that is, Sand blasting is preferred.
[0053]
Moreover, application | coating of the coating film with respect to the outer surface of the exterior board molded article for motor vehicles forms a 15-150 micrometer coating film by spraying a coating material with an air spray gun similarly to the well-known coating method.
[0054]
【Example】
An experiment for confirming the effect of the present invention was performed, and the result will be described.
[0055]
As an experimental example, using a blow molding machine equipped with an extruder with a screw diameter of 90 mm, as shown in FIG. 3, the length L is 1200 mm, the width D is 180 mm, the height H is 90 mm, and the average wall thickness is After blow molding the 3 mm spoiler molded article 10, a spoiler was produced in which a 50 μm coating film was applied to the outer surface of the spoiler molded article 10.
[0056]
Experimental Examples 1 to 7 are polypropylene (Nippon Polychem, Inc.) using a mold having fine irregularities with a surface roughness of a cavity of 5.0 μm by sandblasting and an average crest interval of 25 μm and talc as an inorganic filler. Each sample was manufactured by extruding a Paris manufactured by Co., Ltd., EC-9, A = 115 ° C., B = 162 ° C.) at 220 ° C., and changing the surface temperature of the cavity.
[0057]
Experimental example 8 uses a mold having micro unevenness with a surface roughness of the cavity of 5.0 μm and an average crest interval of 25 μm, the surface temperature of the cavity is constant, and the content of the inorganic filler is changed. 9 was produced.
[0058]
In Experimental Example 9, Samples 1 to 9 were manufactured in the same manner as in Experimental Example 5 except that a mold having micro unevenness with an average crest interval of 10 μm and a cavity surface roughness of 2.0 μm was used.
[0059]
In Experimental Example 10, Samples 1 to 9 were manufactured in the same manner as in Experimental Example 5 except that a mold having fine irregularities with a cavity surface roughness of 1.0 μm and an average peak interval of 10 μm was used.
[0060]
In Experimental Example 11, Samples 1 to 9 were produced in the same manner as in Experimental Example 5 except that a mold having fine irregularities with a cavity surface roughness of 0.9 μm and an average peak interval of 10 μm was used.
[0061]
In Experimental Example 12, Samples 1 to 9 were manufactured in the same manner as in Experimental Example 5 except that a mold having micro unevenness with a cavity surface roughness of 0.8 μm and an average peak interval of 10 μm was used.
[0062]
In Experimental Example 13, Samples 1 to 9 were manufactured in the same manner as in Experimental Example 5 except that a mold having fine irregularities with a cavity surface roughness of 9.0 μm and an average peak interval of 30 μm was used.
[0063]
In Experimental Example 14, Samples 1 to 9 were produced in the same manner as in Experimental Example 5 except that a mold having fine irregularities with a cavity surface roughness of 10 μm and an average peak interval of 30 μm was used.
[0064]
In Experimental Example 15, Samples 1 to 9 were manufactured in the same manner as in Experimental Example 5 except that a mold having micro unevenness with a cavity surface roughness of 3.0 μm and an average peak interval of 10 μm was used.
[0065]
In Experimental Example 16, Samples 1 to 9 were manufactured in the same manner as in Experimental Example 5 except that a mold having fine irregularities with a surface roughness of the cavity of 3.0 μm and an average crest interval of 9 μm was used.
[0066]
In Experimental Example 17, Samples 1 to 9 were produced in the same manner as in Experimental Example 5 except that a mold having a micro unevenness with a surface roughness of the cavity of 5.0 μm and an average peak interval of 150 μm was used.
[0067]
In Experimental Example 18, Samples 1 to 9 were manufactured in the same manner as in Experimental Example 5 except that a mold having minute irregularities with a surface roughness of the cavity of 5.0 μm and an average peak interval of 160 μm was used.
[0068]
Experimental Example 19 uses a mold having fine irregularities with a surface roughness of a cavity of 5.0 μm and an average crest interval of 25 μm by sandblasting, and a polypropylene / high density polyethylene blend resin is extruded at 210 ° C. Samples 1 to 9 were produced by changing the temperature. Here, the polypropylene / high density polyethylene resin includes polypropylene (Nippon Polychem Co., Ltd., EC-9, A = 115 ° C., B = 162 ° C.) and high density polyethylene (Asahi Kasei Kogyo Co., Ltd., B-970, A = 121 ° C., B = 130 ° C.) at a ratio of 70:30, and each peak temperature of this blend resin is A116.8 ° C. and B = 152.4 ° C.
[0069]
Experimental Example 20 produced Samples 1 to 9 in the same manner as Experimental Example 19 except that the cavity surface temperature was kept constant and the content of the inorganic filler was changed.
[0070]
In Experimental Example 21, Samples 1 to 9 were manufactured in the same manner as in Experimental Example 19 except that a mold having micro unevenness with a cavity surface roughness of 2.0 μm and an average peak interval of 10 μm was used.
[0071]
In Experimental Example 22, Samples 1 to 9 were manufactured in the same manner as in Experimental Example 19 except that a cavity having a surface roughness of 1.0 μm and a mold having fine irregularities with an average crest interval of 10 μm was used.
[0072]
In Experimental Example 23, Samples 1 to 9 were manufactured in the same manner as in Experimental Example 19 except that a mold having fine irregularities with a surface roughness of the cavity of 0.9 μm and an average peak interval of 10 μm was used.
[0073]
In Experimental Example 24, Samples 1 to 9 were produced in the same manner as in Experimental Example 19 except that a mold having fine irregularities with a cavity surface roughness of 0.8 μm and an average peak interval of 10 μm was used.
[0074]
In Experimental Example 25, Samples 1 to 9 were manufactured in the same manner as in Experimental Example 19 except that a mold having fine irregularities with a cavity surface roughness of 9.0 μm and an average crest interval of 30 μm was used.
[0075]
In Experimental Example 26, Samples 1 to 9 were manufactured in the same manner as in Experimental Example 19 except that a mold having fine irregularities with a cavity surface roughness of 10 μm and an average peak interval of 30 μm was used.
[0076]
In Experimental Example 27, Samples 1 to 9 were manufactured in the same manner as in Experimental Example 19 except that a mold having fine irregularities with a cavity surface roughness of 3.0 μm and an average peak interval of 9 μm was used.
[0077]
In Experimental Example 28, Samples 1 to 9 were manufactured in the same manner as in Experimental Example 19 except that a mold having fine irregularities with a surface roughness of the cavity of 3.0 μm and an average peak interval of 10 μm was used.
[0078]
In Experimental Example 29, Samples 1 to 9 were produced in the same manner as in Experimental Example 19 except that a mold having a micro unevenness with a cavity surface roughness of 5.0 μm and an average peak interval of 150 μm was used.
[0079]
In Experimental Example 30, Samples 1 to 9 were manufactured in the same manner as in Experimental Example 19 except that a mold having micro unevenness with a cavity surface roughness of 5.0 μm and an average peak interval of 160 μm was used.
[0080]
Evaluations of Experimental Examples 1 to 30 are shown in Tables 2 to 31.
[0081]
The evaluation criteria in Tables 2 to 31 are as follows.
[0082]
In the table, Rt represents the surface roughness of the molded product, the unit is μm, Sm represents the average crest distance of the rough surface of the molded product, and the unit is μm. Deformation, rough skin, air marks, die lines, and irregularities were visually judged after blow molding and before coating.
[0083]
Deformation
○: Not seen.
Δ: Slightly seen, but no problem.
X: Seen.
[0084]
Rough skin
◯: There is no rust skin-like unevenness on the surface and it is uniform.
Δ: Slightly crusted skin is observed.
X: Remarkable crust skin-like irregularities are present on the surface.
[0085]
Air mark
○: Not generated.
Δ: Almost no occurrence
X: It has occurred.
[0086]
Die line
○: Not generated.
Δ: Almost no occurrence
X: It has occurred.
[0087]
Buzz
○: Not generated.
Δ: Almost no occurrence
X: It has occurred.
[0088]
Appearance of painted surface
○: Yuzu skin was not generated.
(Triangle | delta): Generation | occurrence | production of the skin was seen slightly.
X: Yuzu skin was generated.
[0089]
[Table 2]

[0090]
[Table 3]

[0091]
[Table 4]

[0092]
[Table 5]

[0093]
[Table 6]

[0094]
[Table 7]

[0095]
[Table 8]

From Tables 2 to 8, it can be seen that when the surface temperature Y ° C. of the cavity in contact with the Paris reaches 175 ° C., the molding cycle increases to 300 seconds. In addition, from Table 7, when the surface temperature Z ° C. of the cavity at the time of starting the mold opening when taking out the automotive exterior plate molded product exceeds 100 ° C., the molded product is deformed, and the appearance of the coated surface of the molded product itself I can see that it falls.
[0096]
[Table 9]

In Table 9, when the filler content exceeds 40% by weight, the elongation of the Parisn itself deteriorates, and the surface becomes rough, resulting in deterioration of the coated surface of the molded product. In sample 9 in which the filler was 50% by weight, since the elongation of the parison was further poor, it was impossible to mold with a hole in the molded product at the time of blow molding.
[0097]
It can be seen that when the filler content exceeds 35% by weight, the elongation of the Paris is extremely deteriorated, the surface of the molded product is deteriorated, and as a result, the painted surface is deteriorated.
[0098]
Conversely, it can be seen that when the filler content is less than 3% by weight, the time required for the sanding process of the parting line portion becomes as long as nearly 40 minutes.
[0099]
[Table 10]

[0100]
[Table 11]

[0101]
[Table 12]

[0102]
[Table 13]

[0103]
[Table 14]

[0104]
[Table 15]

From Tables 10 to 15, it can be seen that the surface roughness Rt of the minute irregularities of the cavity needs to be 0.9 to 9.0 μm.
[0105]
In Table 13, it can be seen that the appearance of the coated surface is extremely bad, and Table 15 is also poor compared to the same. From this, it can be seen that the Rt of the cavity needs to be 0.9 to 9.0 μm.
[0106]
[Table 16]

[0107]
[Table 17]

[0108]
[Table 18]

[0109]
[Table 19]

From Table 16 to Table 19, it can be seen that the average peak spacing Sm of the minute irregularities of the cavity needs to be 10 to 150 μm.
[0110]
In Table 17, it can be seen that the appearance of the coating surface is extremely bad, and Table 19 is also poor compared to the same. From this, it can be seen that the average peak spacing Sm of the cavities needs to be 10 to 150 μm.
[0111]
From Tables 2 to 19, it can be seen that the surface of the automotive exterior molded article needs to have a surface roughness Rt of 0.9 to 9.0 μm and an average peak spacing Sm of 10 to 150 μm.
[0112]
[Table 20]

[0113]
[Table 21]

In Table 21, when the filler content exceeds 40% by weight, the elongation of the Parisn itself deteriorated, and the surface was roughened. As a result, the coated surface of the molded product was deteriorated. In sample 9 in which the filler was 50% by weight, since the elongation of the parison was further poor, it was impossible to mold with a hole in the molded product at the time of blow molding.
[0114]
It can be seen that when the filler content exceeds 35% by weight, the elongation of the Paris is extremely deteriorated, the surface of the molded product is deteriorated, and as a result, the painted surface is deteriorated.
[0115]
Conversely, it can be seen that when the filler content is less than 3% by weight, the time required for sanding the parting line portion becomes as long as nearly 50 minutes.
[0116]
[Table 22]

[0117]
[Table 23]

[0118]
[Table 24]

[0119]
[Table 25]

[0120]
[Table 26]

[0121]
[Table 27]

From Table 22 to Table 27, it can be seen that the molding cycle increases to 300 seconds when the surface temperature Y ° C. of the cavity during adhesion of the Paris reaches 165 ° C.
[0122]
From Table 22 to Table 27, it can be seen that the surface roughness Rt of the minute unevenness of the cavity needs to be 0.9 to 9.0 μm.
[0123]
In Table 25, it can be seen that the appearance of the coated surface is extremely bad, and Table 26 is similarly bad compared to others. Accordingly, it is understood that the Rt of the cavity needs to be 0.9 to 9.0 μm.
[0124]
[Table 28]

[0125]
[Table 29]

[0126]
[Table 30]

[0127]
[Table 31]

From Table 28 to Table 31, it can be seen that the average peak spacing Sm of the minute irregularities of the cavity needs to be 10 to 150 μm.
[0128]
In Table 28, it can be seen that the appearance of the coating surface is extremely bad, and Table 31 is also poor compared to the same. From this, it can be seen that the average peak spacing Sm of the cavities needs to be 10 to 150 μm.
[0129]
From Tables 20 to 31, it can be seen that the surface of the automotive exterior molded article needs to have a surface roughness Rt of 0.9 to 9.0 μm and an average peak spacing Sm of 10 to 150 μm.
[0130]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
[0131]
There is no risk of spots, line marks or air marks on the outer surface of blow molded automatic exterior panel molded products, and the coating is applied directly without polishing or water-polishing the outer surface of the automotive exterior panel molded product. Thus, it is possible to produce an automotive exterior board having excellent mechanical strength such as rigidity and good appearance.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a state in which a Paris is extruded between molds that are opened.
FIG. 2 is a schematic cross-sectional view showing a state in which a blow-molded automotive exterior plate molded product is cooled in a mold and then the mold is opened.
FIG. 3 is a schematic perspective view showing a blow-molded spoiler product.
[Explanation of symbols]
1 Automotive exterior panel moldings
2 Extrusion head
3 Parisun
4,5 mold
4a, 5a cavity
6,7 Heating means
10 Spoiler molded products

Claims (4)

In a method for producing an automotive exterior plate, after blow molding a hollow automotive exterior plate molded product, a 15 to 150 μm coating film is applied to the outer surface of the automotive exterior plate molded product.
The blow molding of the automobile exterior plate molded article is a gold provided with a cavity having minute irregularities having a surface roughness within a range of 0.9 to 9.0 μm and an average crest interval of 10 to 150 μm. A mold is used, and a Paris made of a crystalline resin having a flexural modulus of elasticity of 9000 kg / cm ² or more at 23 ° C. is placed between the opened molds and then the mold is closed, and then a pressurized fluid is introduced into the Paris The surface temperature Y ° C. of the cavity during the close contact is expressed by the following formula: A <Y <1.07B
Here, A: Crystallization peak temperature (° C.) in a DSC curve of a crystalline resin having a flexural modulus at 23 ° C. of 9000 kg / cm ² or more.
B: Melting peak temperature (° C) in the DSC curve of a crystalline resin having a flexural modulus at 23 ° C of 9000 kg / cm ² or more
The manufacturing method of the exterior plate for motor vehicles characterized by heating up so that it may satisfy | fill. In a method for producing an automotive exterior plate, after blow molding a hollow automotive exterior plate molded product, a 15 to 150 μm coating film is applied to the outer surface of the automotive exterior plate molded product.
The blow molding of the automobile exterior plate molded article is a gold provided with a cavity having minute irregularities having a surface roughness within a range of 0.9 to 9.0 μm and an average crest interval of 10 to 150 μm. A mold was used, and after closing the mold made of a crystalline resin having a bending elastic modulus at 23 ° C. of 9000 kg / cm ² or more between the molds opened, the mold closing was started, and the mold immediately before the mold closing was completed The cavity surface temperature Y ° C. is expressed by the following formula: A <Y <1.07B
Here, A: Crystallization peak temperature (° C.) in a DSC curve of a crystalline resin having a flexural modulus at 23 ° C. of 9000 kg / cm ² or more.
B: Melting peak temperature (° C) in the DSC curve of a crystalline resin having a flexural modulus at 23 ° C of 9000 kg / cm ² or more
A method for manufacturing an automotive exterior plate, wherein the mold closing is completed by satisfying a temperature so as to satisfy the conditions, and then a pressurized fluid is introduced into the Paris to closely contact the cavity. 3. The method for manufacturing an automotive exterior board according to claim 1 or 2, wherein an inorganic filler within a range of 3 to 35% by weight is blended with a crystalline resin having a bending elastic modulus at 23 ° C. of 9000 kg / cm ² or more. The manufacturing method of the exterior plate for motor vehicles characterized by these. 3. The method of manufacturing an automotive exterior board according to claim 1 or 2, wherein the surface temperature Z ° C. of the cavity at the start of mold opening when taking out the automotive exterior panel molded product is Z ≦ A-15.
The manufacturing method of the exterior plate for motor vehicles characterized by the above-mentioned.

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