201111150 六、發明說明： 【發明所屬之技術領域】 本發明係關於樹脂之射出成形方法，尤其係關於使用具 有複數之澆口之模具將結晶性樹脂射出成形之方法。 【先前技術】 先前以來’藉由射出成形方法成形之樹脂成形品被使用 於各種領域。射出成形方法係藉由於將熔融狀態之樹脂射 出填充於楔具之内部（模穴）後，冷卻該模具且固化樹脂， 而進行樹脂之成形。 用於射出成形之模具係形成有用w於模穴内；主入樹脂之 澆口，而澆口之個數及配置係由模具之形狀決定。例如， 模具之形狀為複數之情形下，係以使熔融狀態之樹脂確實 填充於模穴内之方式，將複數之堯口設於特定之位置。 ，然而’藉由具有複數之澆口之模具進行射出成形之情 由於從不同之洗口注人之樹脂係於模穴内之某地點 (合流部)合流’因此有時會因該合流部之樹脂對模具的擠 壓不充分而讓樹脂就此固化。該情形會引起合流部之模具 之轉印不良’且會沿著合流部產生稱為熔接線之外觀不 良。 因此，為消_脂成形u料線，❹，如專利文獻 1提案有藉由將射出填充時之模具之表面溫度維持於樹脂 之熱變形溫度以上，來防止合流部之模具之轉印不良的方 法。 再者’為消除結晶性樹脂成形品之熔接線，專利文獻2 143359.doc 201111150 提案有藉由將射出填充時之模具之表面溫度從「结晶性樹 脂之結晶化溫度俄」加熱至「結晶性樹脂之二曰曰化溫 度+2(TC」之範圍，來防止合流部之模具之轉印不良的方 法。 又，專利文獻3提案有藉由使混合於樹脂成分之粉末之 形狀設為不具有方向性者，即使熔接線上該粉末之配向有 所變化，亦無需使光反射率變化便可防止色差的方法。 再者，為提高合流部之樹脂成形品之強度，專利文獻4 中記載有於原料樹脂中添加球狀填料之方法。 另一方面，為防止樹脂成形品之凹痕或翹曲，或為將成 形品輕量化，先前以來係於射出填充時進行使樹脂發泡之 發泡射出成形，例如，專利文獻5中記載有藉由將包含具 有熱膨脹性之微膠囊的樹脂射出成形來製造發泡體之方 法。該微膠囊係將具有包含熱塑性樹脂之殼内包發泡劑的 結構’於射出填充時藉由加熱而膨脹。 [先行技術文獻] [專利文獻] [專利文獻1]日本專利第3859620號公報 [專利文獻2]曰本特開2008-44384號公報 [專利文獻3]曰本特開平8·4 1284號公報 [專利文獻4]日本特開2006-52342號公報 [專利文獻5]曰本特開2008-127397號公報 【發明内容】 [發明所欲解決之問題] 143359.doc 201111150 然而’本申請案發明者察覺，雖然藉由專利文獻1所記 載之方法可消除非晶性樹脂之熔接線，但在將結晶性樹脂 射出成形之情形’雖然可使由不同之澆口注入之樹脂之合 々’L。卩變得平坦且消除熔接線之合流部的凹陷，但以目視確 5忍該合流部時’仍會殘留合流部之痕跡（交界線）而成為外 觀不良。此種外觀不良為先前未曾察覺者，且據判其原因 係以合流部為交界，於其樹脂成形品之表面之光澤、反射 狀況出現差異所致。 再者專利文獻3所記载之方法，雖藉由使具有混合於 樹脂成分之具有金屬光澤之粉末的形狀設為不具有方向 性，而可抑制因具有上述金屬光澤之粉末形狀所引起之光 反射方向的偏差、色差，但未能防止樹脂合流部之熔接 線、及以成形品主材之樹脂之合流部為交界之表面光澤、 反射狀況之差異。 專利文獻1至5中任-者皆可在將結晶性樹脂射出成形之 情形中使之上述樹脂的合流部變得平坦而消除溶接線即合 流部的凹陷’但對於以目視確認該合流部時存在於合流= 之痕跡(交界線)之外觀不良卻無著墨，且毫無記載關於消 除此種外觀不良（以後單稱為「外觀不良」）之方法。 本發明係馨於上述實情而完成者，其目的在於提供—種 即使在使用具有複數之濟口之模具將結晶性樹脂射出成形 Π::可防止合流部之痕跡殘留成為外觀不良的射 出成形万法。 [解決問題之技術手段] 143359.doc 201111150 本發明之射出成形方法之特微主 诚為’其係用具有複數之澆 口之模具將結晶性樹脂射出成形，〇 n ®战形，且具備：將上述模具之 /JBL度加熱至上述結晶性樹脂之炫融、、θ许〗μ 邮，皿度-100C以上之溫度 的步驟；於加熱至上述結晶性槲 樹知之熔融溫度-loot以上 之溫度的上述模具内，經由上过〔適 (複數之澆口而射出填充含 有球狀體之上述結晶性樹脂的步 曰刃艾驟，及以固化射出填充於 上述模具内之上述結晶性樹脂之方式，而冷卻上述模具的 步驟；又’上述球狀體係、在射出步驟及冷卻步驟中可實質 維持球狀形狀的球狀體。 該射出成形方法係於成形對象之結晶性樹脂添加球狀 體，且將射出成形時之模具之溫度加熱至結晶性樹脂之溶 融皿度-100C以上的溫度。根據本申請案發明者之研討结 果明確，根據上述射出成形方法，即使用具有複數之洗口 之模具將結晶性樹脂射出成形，亦可防止合流部之痕跡殘 留成為外觀不良。 其原因認為係，包含於結晶性樹脂之球狀體於射出填充 時、及冷卻固化時，欲沿結晶性樹脂之流動方向配向之分 子，在球狀體表面附近僅沿等方形狀體之球狀體的表面固 化，其結果，球狀體係作為阻礙沿結晶性樹脂之流動方向 之分子配向的抵抗體而發揮功能，其抑制合流部之兩側之 結晶性樹脂之配向，而不產生光澤之差異。又認為，藉由 球狀體，可減小射出填充時、及冷卻固化時沿結晶性樹脂 之流動方向而配向之分子的比例，因此可緩和樹脂成形品 之收縮率之各向異性，且更加淡化合流部之痕跡。 143359.doc 201111150 度加献至姓Γ射出成形方法由於係將射出成形時之模具溫 二=?樹脂之溶融溫度，以上的溫度，因此 升溫能量脂之㈣性·轉印性確保及升溫時間縮短. 牟："。且可適度保持射出於模穴之樹脂之流動性 厂人1 ，從而提高合流部之模具之轉印性。因此，可防 止因合流部Μ之模具之轉印不良所致之外觀不良。 、’[射出成形H上述球狀體宜係具有熱膨脹性之微 囊，且上述模具係在Τ1$Τ$Τ2之範圍加熱。 。、中Τ係上述模具之溫度’ T1係藉由上述微膠囊之周圍 之減壓而使上述微膠囊開始膨脹的溫度，τ2係對於上述微 膠囊之溫度之膨腸變形程度由緩增轉為急增的拐點溫 度。） 藉此，由於微膠囊之膨脹時結晶性樹脂係強壓於模具， 因此可更加提高合流部之模具之轉印性，且可更確實地防 止合流部之痕跡殘留成為外觀不良。且’先前之化學發泡 劑中發泡氣體係單純之氣泡，故於該氣泡露出於成形品表 面時，會因氣泡之破裂、或隨模具壁面之冷卻之發泡氣體 的溫度降低等，使氣泡失去膨脹力，與此相對，微膠囊由 於其發泡氣體係包於殼中而不會因破泡等失去膨脹力，因 此藉由模具之冷卻而將結晶性樹脂固化收縮時，微膜囊之 周邊被減壓，故可促進微膠囊之膨脹，且於結晶性樹脂之 收縮之區域使微膠囊膨服而埋入。藉此使樹脂分子之可矛多 動的樹脂區域縮小，因此可更加抑制結晶性樹脂之分子配 向，從而更確實地防止合流部之痕跡殘留成為外觀不良。 143359.doc 201111150 再者’先前之化學發泡劑中發泡氣體係單純之氣泡，故於 該氣泡露出於成形品表面時，會因氣泡之破裂或變形等使 得不能維持氣泡之球狀形狀，與此相對，上述微膠囊之殼 係具有充分的剛性，於射出成形時破裂或變形較少，因此 τ充刀阻礙結晶性樹脂之分子配向，進而更加確實地防止 合流部之痕跡殘留成為外觀不良。 上述射出成形方法中’上述結晶性樹脂可為烯烴系樹 脂。 上述射出成形方法中，對於一般廣泛使用作為結晶性樹 脂之烯烴系樹脂亦為有效，其可防止合流部之痕跡殘留成 為外觀不良’而製造外觀優良之烯烴系樹脂成形品。 上述射出成形方法中以上述球狀體之直徑為5〇 μιη以上 為佳。 藉由將球狀體之直徑設為充分大於結晶性樹脂之分子尺 寸的50 μιη以上，可減少樹脂成形品中結晶性樹脂所占之 區域，從而縮小結晶性樹脂之分子的自由體積（自由區 域）。藉此，射出填充時、及冷卻固化時沿結晶性樹脂之 流動方向的分子配向被更加抑制，因此可更確實地防止合 流部之痕跡殘留成為外觀不良。 另，本說明書中，球狀體之「直徑」係指球狀體之數量 平均粒徑，在球狀體為熱膨脹性之微膠囊之情形下，其係 意指微膠囊之熱膨脹後的數量平均粒徑。 上述射出成形方法，上述模具之冷卻宜係於上述模具之 内部流動冷卻水而強制進行。 143359.doc 201111150 藉此，藉由於射出填充後迅速固化樹脂，可提高樹脂成 形品之生產效率。 [發明之效果] 根據本發明’藉由使結晶性樹脂含有球狀體，且將射出 成形時之模具之溫度加熱至結晶性樹脂之熔融溫度_10(rc 以上的溫度’即使在使用具有複數之澆口之模具將結晶性 樹脂射出成形之情形下’亦可防止合流部之痕跡殘留成為 外觀不良。 【實施方式】 以下茲參照添加圖式說明本發明之實施形態。 圖1係顯示本實施形態之射出成形方法所用之模具之一 例的剖面圖。如該圖所示’模具丨〇係包含模具上部（可動 模具）10A及模具下部（固定模具）10B。模具1〇係具有樹脂 成形品之反轉形狀之模穴12、及用以於模穴12填充熔融樹 脂之澆口 14。 另，圖1係顯示澆口 14亦發揮流道（sprue)之作用的例（所 謂直接洗口），但洗口 14之種類並非限定於此，例如，亦 可為由模具1 〇之側面注入樹脂之側澆澆口。 洗口 14(14A、14B)在圖1所示之例中係分別設於模穴12 之兩端。如此，當於具有複數之淹口14(14八、14B)之模具 1〇中射出填充樹脂時’由不同之澆口 14八及148注入之樹 脂20將分別於圖1之箭頭方向流動，而在模穴12内之合流 部Μ合流。 本申請案發明者察覺，在用具有複數之澆口 14之模具1〇 143359.doc 201111150 將、·•。明ι±樹月日藉由射出成形而加熱冷卻成形之情形，雖然 可使射出填充時之炼融樹脂之合流部Μ變得平坦而消除溶 接線之“L部的凹陷，但以目視確認該合流部肖，仍會殘 留口抓。卩之痕跡（交界線）而成為樹脂成形品之外觀不良。 該外觀不良為先前未曾察覺者，且據判其原因係以合流部 Μ為交界，於其樹脂成形品之表面之光澤、反射狀況出現 差異所致。 本實施形態之射出成形方法，其詳細内容將後述，其係 使成形對象之結晶性樹脂2〇含有球狀體，且將射出成形時 之模具1〇之溫度加熱至結晶性樹脂2〇之熔融溫度_1〇〇它以 上的溫度。根據本申請案發明者之研討結果判明，根據該 射出成形方法，即使在使用具有複數之洗口 14之模具丨〇將 結晶性樹脂20射出成形之情形下，亦可防止合流部M之痕 跡殘留成為外觀不良。 其原因據判為，結晶性樹脂20中所含之球狀體於射出填 充時及冷卻固化時，所要沿著結晶性樹脂之流動方向而配 向之分子’只會在球狀體表面附近沿著等向性形狀體之球 狀體的表面固化’其結果’球狀體係作為阻礙沿著結晶性 樹脂20之流動方向之分子配向的抵抗體而發揮功能，而抑 制合流部Μ之兩側之結晶性樹脂20之配向，因而不會產生 光澤、反射狀況之差異《又據判為，藉由球狀體，可減小 射出填充時及冷卻固化時沿著結晶性樹脂2〇之流動方向而 配向之分子的比例，因此可緩和樹脂成形品之收縮率之各 向異性，且更加淡化合流部Μ之痕跡。 143359.doc -10· 201111150 再者，上述射出成形方法由於係將射出成形時之模具10 之溫度加熱至結晶性樹脂2〇之熔融溫度-i〇(TC以上的溫 度，因此可兼顧結晶性樹脂之流動性、轉印性確保及升溫 時間縮短、升溫能量抑制。更且可適度料射出到模穴12 之樹月曰20之々IL動性（柔軟性），從而提高合流部μ之模具1 〇 之轉印性。因此，可防止因合流部Μ之模具1〇之轉印不良 所致之外觀不良。 以下詳細說明本實施形態之射出成形方法。 結晶性樹脂2 0只要是結晶化度比較高者則無特別限定， 可為聚乙烯(ΡΕ)或聚丙烯(ρρ)等之烯烴系樹脂。本實施形 態之射出成形方法’對於一般廣泛使用作為結晶性樹脂之 烯烴系樹脂亦為有效，其可防止合流部撾之痕跡殘留成為 外觀不良，而製造外觀優良之烯烴系樹脂成形品。 結晶性樹脂20所含有之球狀體只要是大致球形狀之固體 則無特別限定，例如可使用任意材質之球狀填料或微膠 囊。 尤其，作為球狀體，如專利文獻5(曰本特開2〇〇8_127397 號公報）所記載，宜使用具有由重合體構成之殼包含有發 泡劑（核）之結構的熱膨脹性微膠囊。 由於藉由使作為球狀體而添加之熱膨脹性之微膠囊於射 出填充時或射出填充後膨脹，而將結晶性樹脂2〇強力擠壓 到模具10，因此可更加提高合流部Μ之模具10之轉印性， 且可更確實地防止合流部Μ之痕跡殘留成為外觀不良。 且’先前之化學發泡劑其發泡氣體係單純之氣泡，故於該 143359.doc -11 · 201111150 ι包路出於成形品表面時，t因氣泡之破裂、或隨模具壁 面之冷卻而使發泡氣體的溫度降低等，使氣泡失去膨脹 力’、此相對，微膠囊則由於其發泡氣體係包於殼中而不 會因破泡等失去膨脹力’因此藉由模具10之冷卻而將結晶 :樹脂20固化收縮時’微膠囊之周邊會被減壓，故可促進 微膠囊之膨脹，使微膠囊膨脹而埋入結晶性樹脂2〇之收縮 之區域。藉此使樹脂分子可移動的樹脂區域縮小，因此可 更加抑制結晶性樹脂20之分子配向，從而更確實地防止合 流部Μ之痕跡殘留成為外觀不良。再者，先前之化學發泡 劑其發泡氣體係單純之氣泡，故於該氣泡露出於成形品表 面時，會因氣泡之破裂或變形等而無法維持氣泡之球狀形 狀，與此相對，上述微膠囊之殼則具有充分的剛性，於射 出成形時少有破裂或變形，因此可充分阻礙結晶性樹脂2〇 之分子配向，進而更加確實地防止合流部河之痕跡殘留成 為外觀不良。 又，球狀體可使用一種類型者，亦可併用複數種。例 如，亦可於結晶性樹脂2〇中添加熱膨脹性微膠囊、與包含 金屬粒、金屬粉或玻璃粒、玻璃粉而構成之球狀填料之兩 者。在於結晶性樹脂20中添加熱膨脹性微膠囊、與包含金 屬粒、金屬粉或玻璃粒、玻璃粉而構成之球狀填料之兩者 的情形下，可獲得抑制先前以合流部Μ為交界之兩側因結 晶性樹脂20之配向而產生之外觀差的均一外觀成形品。 又，添加於結晶性樹脂20中之球狀體之直徑（數量平均 粒徑）宜為50 μπι以上。尤其在球狀體為熱膨脹性之微膠囊 143359.doc 12 201111150 之情形下，膨脹後之直徑為5 0 μηι以上較佳。藉由將球狀 體之直徑設為充分大於結晶性樹脂20之分子尺寸的5〇 μιη 以上，可減少樹脂成形品中結晶性樹脂20所占之區域，從 而縮小結晶性樹脂20之分子的自由體積（自由區域）。尤 其’熱膨脹性膠囊藉由因膨脹而擴大球狀體之尺寸，可縮 小熔融樹脂之自由體積的尺寸，且藉由因發泡氣體壓力而 將球狀形狀擠壓於熔融樹脂’可抑制使熔融樹脂之配向沿 著球狀體表面於分子之單一方向配向。藉此，可更加抑制 射出填充時沿著結晶性樹脂20之流動方向之分子配向，因 此可更確實地防止合流部Μ之痕跡殘留成為外觀不良。 射出填充時之模具10之溫度Τ係加熱至結晶性樹脂2 〇之 溶融溫度Tm-100°C以上。從兼顧結晶性樹脂2〇之流動性、 轉印性確保及升溫時間縮短、升溫能量抑制的觀點考慮， 且將射出填充時之模具1 0之溫度T加熱至Tm-100g T幺 Tm+50°C之範圍。 模具10之溫度T在球狀體為微膠囊之情形或非為該情形 時，為 Tm-100 C 以上，且為 Tm-100°C g Tg Tm+50°C 較 佳。尤其在球狀體為微膠囊之情形下，從維持球形狀、確 實阻礙結晶性樹脂20之配向的觀點考慮，將模具丨〇之溫度 T 設為Tm-100°C 以上（以Tm-l〇〇t gT$Tm+5〇t：為佳）、且 設定於T1STST2之範圍較佳，設定之範圍 更佳。惟T1係藉由微膠囊之周圍（結晶性樹脂2〇)之減壓而 使微膠囊開始膨脹的溫度，T2係相對於微膠囊之溫度之膨 脹變形程度由緩增轉為急増的拐點溫度，Te係根據微膠囊 143359.doc 13· 201111150 之内部之發泡劑因分解、揮發而開始膨脹之溫度（>τ 1)。 例如，具有丙烯腈系之殼之微膠囊的情形，Τ1為接近Te_ 70。(：之值，T2為接近Te + 30°C之值’因此將模具1〇之溫度 T設定於Te-70°C S TS Te+30°C之範圍較佳，而設定於 Te$TSTe+30°C之範圍為更佳。 圖2係顯示本實施形態之射出成形方法之射出填充時模 具溫度及合流部之樹脂壓力之一例的圖表。該圖中係將射 出填充時之模具溫度顯示於下段之圖表，而將射出填充時 之合流部之樹脂壓力顯示於上段之圖表。 圖2所示之例中，係於時刻tl開始模具10之加熱，且持 續進行模具10之加熱直至模具10之溫度達到Τμαχ(Τπι_ 100°C S Τ)為止（惟Tm為結晶性樹脂20之熔融溫度）。其 後，在使模具10冷卻之前（t<t4)，使模具10維持在以以之 溫度。 於維持在溫度ΤΜΑχ之模具1〇之模穴12中，經由複數之繞 口 14(14Α、14Β)開始結晶性樹脂20之射出填充（t=t2)。若 繼續進行結晶性樹脂20之射出填充，則於時刻t3，由不同 之洗口 14(14A、14B)注入之結晶性樹脂20會在合流部厘合 流，使得合流部Μ之樹脂壓力開始上升。 如此進行結晶性樹脂20之射出填充後，於時刻t4將模具 10冷部，且固化填充於模穴12之結晶性樹脂20。從迅速固 化結晶性樹脂2〇之觀點考慮，模具1〇之冷卻較佳於模具1〇 之内部流動冷卻水而強制進行。 最後，藉由將固化之結晶性樹脂2〇從模具1〇卸下，獲得 143359.doc •14· 201111150 所期望之形狀之樹脂成形品。 圖3係顯示藉由本實施形態之射出成形方法將結晶性樹 脂20射出成形時合流部μ周邊之情形的圖。 將含有球狀體22之結晶性樹脂20射出填充到圖3(a)所示 之模具10之模穴12内時，由不同之澆口注入之結晶性樹脂 20將分別於模穴12内向合流部M流動（參照圖3(b))。其 後，如圖3(c)所示，於合流部M，由不同之澆口注入之結 晶性樹脂20之流動前沿F將相互接觸，使合流部M之樹脂 壓力開始上升。 若繼續進行結晶性樹脂20之射出填充，則合流部M之結 晶性樹脂20之合一化將進展（參照圖3(d))，最終完成合流 部Μ之模具1 〇之轉印。 如上述，根據本實施形態之射出成形方法，係使成形對 象之結晶性樹脂20中含有球狀體22，且將射出成形時之模 具10之溫度加熱至結晶性樹脂2〇之熔融溫度_1〇〇它以上之 溫度。又，若於上述加熱後維持該溫度，則不僅通常之結 晶性樹脂’對於生物分解性樹脂等之結晶化速度特別慢的 結晶性樹脂亦更加有效。 因此，結晶性樹脂20中所含之球狀體22係作為阻礙射出 填充時及冷卻固化時沿著結晶性樹脂2G之流動方向之分子 配向的抵抗體而發揮功能’且合流部M之兩側之結晶性樹 脂Μ之配向程度大致相同’不會產生光澤之差異。又，由 於藉由球狀體22減小射出填充時及冷卻固化時沿著結晶性 樹脂20之流動方向而配向之分子的比例，因此緩和樹脂成 143359.doc 15 201111150 形品之收縮率之各向異性，且更加淡化合流部M之痕跡。 尤其在球狀體為熱膨脹性之微膠囊之情形下，發泡氣體被 八有充幺剛性之微膠囊的殼包圍，而少有破裂或變形故可 維持球狀形狀，藉此使微膠囊作為阻礙分子配向之抵抗體 而發揮功此’故緩和樹脂成形品之收縮率之各向異性，且 更加淡化合流部Μ之痕跡。 再者，由於射出成形時之模具1〇之溫度係加熱至結晶性 樹脂20之熔融溫度_i〇(rc以上的溫度，因此可兼顧結晶性 樹脂之流動性、轉印性確保及升溫時間縮短、升溫能量抑 制。更且可適度保持射出到模穴丨2之樹脂2〇之流動性（柔 軟性），從而提高合流部M之模具丨〇之轉印性。因此，可防 止因合流部Μ之模具10之轉印不良所致之外觀不良。 以上詳細說明了本發明之一例，但本發明不限定於此， S然可在不脫離本發明之主旨的範圍内進行各種改良或變 形。 [實施例] 根據上述之實施形態之方法，如以下所示進行射出成 形，並評價樹脂成形品之外觀。 [實施例1 ] 模具10使用具有3個澆口 14之汽車前栅用的模具，結晶 性樹脂20使用熔融溫度為165°C之聚丙烯（pp，Japan Polypropylene株式會社製，Novatec-pp)。且，於結晶性樹 脂20内’作為球狀體而添加2 wt%之熱膨脹性之微膠囊（積 水化學工業株式會社製，ADVANCELL，發泡後直_ 143359.doc •16· 201111150 Φ80〜200 μηι，T1=9rc，T2 = 195t：，Te=i65^。且模具 之加熱’係用蒸汽作為熱媒體流體進行。 對於結晶性樹脂20之模具10之射出填充，係使用三菱塑 膠技術株式會社製之450MEII-70DD而如下進行。 首先，從兼顧流動性、轉印性確保及升溫時間縮短、升 溫能量抑制之觀點考慮，將射出填充時之模具1〇之溫度預 先加熱至120°C。 於該模具1〇之模穴12内，經由3個澆口 14而射出填充結 晶性樹脂20 ^此時，將結晶性樹脂2〇之溫度（即射出成形 機之作動缸溫度）設定為230°C。 於結晶性樹脂20之射出填充後，為促進微膠囊之膨脹， 不進行保壓步驟而將模具10冷卻，使模穴12内之結晶性樹 脂20固化。藉此獲得圖4所示之樹脂成形品。 另，本實施例係於射出填充後冷卻模具1〇，然而為縮短 成形週期，亦可從射出填充完畢前開始冷卻。 又射出填充後，右藉由未圖示之可動模盤之後退或模 具中子油壓缸之後退而擴大模穴12，亦可獲得無外觀不良 之結晶性樹脂20之輕量的發泡成形品。 又，本實施例中模具之加熱，係使用蒸汽作為加熱媒體 流體進行，然而不僅可使用加熱媒體流體，亦可使用電阻 式加熱器、高頻式加熱器等之其他加熱手段。 [實施例2] 本實施例除取代聚丙烯（PP)而使用聚乙烯（PE)，及將模 具10之預先加熱之溫度設為l〇(TC以外，其餘皆以與實施 143359.doc -17· 201111150 例1相同之條件製作樹脂成形品。另，所使用之聚乙婦 (PE)之熔融溫度為135°C。 [比較例1 ] 本比較例除不對模具20進行至120°C之預備加熱以外， 其餘皆係以與實施例1相同之條件製作樹脂成形品。 [比較例2] 本比較例除不於結晶性樹脂20中添加球狀體，及於射出 填充後以45 MPa附加10秒保壓以外，其餘皆係以與實施例 1相同之條件製作樹脂成形品。 [比較例3] 本比較例除不於結晶性樹脂20中添加球狀體，而係於結 晶性樹脂20中注入〇.5 wt%之超臨界氮氣作為發泡劑進行 成形以外’其餘皆係以與實施例1相同之條件製作樹脂成 形品。 [比較例4] 本比較例除不於結晶性樹脂2〇中添加球狀體，而係於結 晶性知Μ曰20中以色母粒混合3 wt%之化學發泡劑（碳酸氣） 作為發泡劑進行成形以外，其餘皆係以與實施例丨相同之 條件製作樹脂成形品。 [比較例5] 本比較例除於結晶性樹脂2〇中作為球狀體混煉丨〇 之φ20 μιη之鋁粉而非微膠囊，及於射出填充後以45 附 加10秒保壓以外，其餘皆係以與實施例丨相同之條件製作 樹脂成形品。 143359.doc -18· 201111150 [實施例及比較例之比較探討] 以目視觀察了上述實施例1及2與比較例1〜5所獲得之樹 脂成形品。且將樹脂成形品之外觀評價結果顯示於下記之 表。 表1 ·樹脂成形品之外觀評價結果 \ 模具之預 備加熱 樹脂 球狀體 發泡劑 合流部Μ 之痕跡 (交界線） 合流部 凹陷 銀痕 實施例 1 有 ΡΡ 微膠囊 微膠囊 無 無 無 實施例 2 有 ΡΕ 微膠囊 微膠囊 無 無 無 比較例 1 無 ΡΡ 微膠囊 微膠囊 有 有 輕微 比較例 2 有 ΡΡ 無 無 有 無 無 比較例 3 有 ΡΡ 無 超臨界氣體 (氮氣） 有 無 無 比較例 4 有 ΡΡ 無 化學發泡劑 (碳酸氣） 有 無 無 比較例 5 有 ΡΡ 鋁粉 無 有 無 無 由該表可知，藉由於射出填充時將模具10之溫度加熱至 結晶性樹脂20之熔融溫度-100°c以上的溫度，且使結晶性 樹脂20含有球狀體，可使合流部Μ之痕跡不殘留成為外觀 不良（實施例1及2)。 另一方面，在未進行模具10之預備加熱之情形（比較例 1)、或結晶性樹脂20中未含有球狀體之情形（比較例2〜4)、 及含有小徑之球狀體之情形（比較例5)，雖可防止合流部之 143359.doc -19- 201111150 凹陷與銀痕，但以合流部M為交界之樹脂成形品之表面的 光澤、及因反射狀況之差異所產生之合流部M的痕跡（交界 線）會殘留成為外觀不良。 [比較例引起外觀不良之原因] 以下參照圖5〜8說明比較例1〜5引起外觀不良之原因。 另，此處僅說明與上述之實施形態所說明之圖3不同的内 容’而省略與圖3共通之内容之說明。 圖5係顯示以比較例丨之條件進行射出成形時之合流部m 周邊的情形的圖。比較例丨由於未進行模具之預備加熱， 因此合流部Μ中之結晶性樹脂20向模具1〇的擠壓不夠充 勿，使得 '纟a aa性树脂20就此固化（參照圖5(d))，因而使合 流部Μ之痕跡之凹陷殘留成為外觀不良。 圖6係顯示以比較例2之條件進行射出成形時之合流部Μ 周邊的情形的圖。由於比較例2進行了模具之預備加熱， 因此可防止合流部Μ之凹陷、銀痕及模具1〇之轉印不良（參 照圖6(e))。然而，由於比較例2中未使結晶性樹脂2〇中含 有球狀體，因此結晶性樹脂20沿著流動方向進行分子配 向’而產生因合流部Μ之兩側之配向程度之差異所引起的 光澤差。因此使比較例2中合流部Μ之痕跡殘留成為外觀 不良（交界線）。 圖7係顯示以比較例3及4之條件進行射出成形時之合流 部Μ周邊的情形的圖。由於比較例3及4進行了模具之預備 加熱’因此可防止合流部Μ之凹陷、銀痕及模具〗〇之轉印 不良（參照圖7(e))。然而，由於比較例3及4未使結晶性樹 143359.doc -20- 201111150 脂20含有球狀體，因此結晶性樹脂20會沿著流動方向進行 分子配向，而產生因合流部Μ之兩侧之配向程度之差異戶斤 引起的光澤差。因此使比較例3及4中合流部μ之痕跡殘留 成為外觀不良（交界線）。 另，比較例3及4係分別使用超臨界氣體 使結晶性樹脂20發泡’但由於氣泡24會因周圍之結晶性樹 脂20之壓力而容易變形，尤其有可能於成形品表面有氣泡 破裂之情形，因此無法維持氣泡之球狀形狀，且不能充分 阻礙結晶性樹脂20之分子配向，而產生因合流部Μ之兩側 之配向程度之差異所引起的光澤、反射狀況之差。 圖8係顯示以比較例5之條件進行射出成形時之合流部μ 周邊的情形的圖。由於比較例5進行了模具之預備調溫、 及於結晶性樹脂20中混煉球狀形狀之鋁粉，因此可抑制合 流部]νί之凹陷與模具10之轉印不良的色差(參照圖8(小。然 而，比較例5中由於球狀體為小徑，且不會因熱膨服而擴 徑，因此雖球狀體具有充分之剛性，但不能充分縮小結晶 性樹脂20之分子之自由體積(自由區域)，故結晶性樹脂⑽ 會沿著流動方向進行分子配向，而產生因合流部Μ之兩側 之結晶性樹脂2〇之配向程度的差異所引起的光澤差。因此 使痕跡(交界線―良。 ==形方法所用之模具之-例的剖面圖。 -二::射出填充時模具溫度及合流部之樹-力之 143359.doc -21 - 201111150 圖3(aHe)係顯示藉由射出成形方法將結晶性樹脂射出 成形時合流部周邊之情形的圖》 圖4係顯示實施例i及實施例2之汽車散熱格拇成形品形 狀的圖》 圖VaMd)係顯示以比較例〗之條件射出成形時之合流部 周邊的情形的圖。 圖6(a)-(e)係顯示以比較例2之條件射出成形時之合流部 周邊的情形的圖。 圖7(a)-(e)係顯示以比較例3及4之條件射出成形時之合 流部周邊的情形的圖。 圖8(a)-(e)係顯示以比較例5之條件射出成形時之合流部 周邊的情形的圖。 【主要元件符號說明】 10 模具 10A 模具上部 10B 模具下部 12 模穴 14(14A) 洗口 14(14B) 洗口 20 結晶性樹脂 22 球狀體 24 氣泡 F 流動前沿 Μ 合流部 143359.doc • 22-BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for injection molding of a resin, and more particularly to a method for injection molding a crystalline resin using a mold having a plurality of gates. [Prior Art] Resin molded articles formed by the injection molding method have been used in various fields. In the injection molding method, resin is formed by filling the inside of the wedge (cavity) with the resin in a molten state, cooling the mold, and curing the resin. The mold for injection molding is formed into the cavity; the gate of the resin is introduced, and the number and arrangement of the gates are determined by the shape of the mold. For example, in the case where the shape of the mold is plural, a plurality of openings are placed at specific positions so that the resin in a molten state is surely filled in the cavity. However, 'the injection molding is performed by a mold having a plurality of gates. Since the resin injected from different nozzles is joined to a certain point (joining portion) in the cavity, the resin of the junction is sometimes caused. The extrusion of the mold is insufficient and the resin is cured. In this case, the transfer failure of the mold of the merging portion is caused, and a poor appearance called a weld line is generated along the merging portion. Therefore, in order to prevent the transfer of the mold of the merging portion, it is proposed to maintain the surface temperature of the mold at the time of injection filling at a temperature higher than the heat distortion temperature of the resin. method. In addition, in order to eliminate the fusion of the crystalline resin molded article, Patent Document 2 143359.doc 201111150 proposes to heat the surface temperature of the mold from the "crystallization temperature of the crystalline resin" to "crystallinity" by the injection molding. The method of preventing the transfer failure of the mold of the merging portion in the range of the second temperature of the resin + 2 (TC). Further, Patent Document 3 proposes that the shape of the powder mixed with the resin component is not In the directionality, even if the alignment of the powder on the weld line is changed, there is no need to change the light reflectance to prevent chromatic aberration. Further, in order to increase the strength of the resin molded article in the merging portion, Patent Document 4 describes A method of adding a spherical filler to a raw material resin. On the other hand, in order to prevent dents or warpage of a resin molded article, or to reduce the weight of a molded article, foaming of the resin is performed at the time of injection filling. For example, Patent Document 5 describes a method of producing a foam by injection molding a resin containing microcapsules having thermal expansion properties. The microcapsule system will have The structure of the foaming agent in the shell of the thermoplastic resin is expanded by heating at the time of the injection filling. [Prior Art Document] [Patent Document 1] [Patent Document 1] Japanese Patent No. 3,859,620 [Patent Document 2] JP-A-2008-127397 [Patent Document 5] JP-A-2008-127397 [Patent Document 5] JP-A-2008-127397 [Problem to be Solved by the Invention] 143359.doc 201111150 However, the inventors of the present application have noticed that the melting resin of the amorphous resin can be eliminated by the method described in Patent Document 1, but the crystalline resin is emitted. In the case of forming, although the combination of the resin injected from different gates can be made flat, and the depression of the joint portion of the weld line is eliminated, it is visually confirmed that the junction is still retained. The trace of the part (the boundary line) is a poor appearance. This kind of poor appearance is not observed before, and it is said that the reason is that the merging part is the boundary, and the gloss and reflection state of the surface of the resin molded article are different. Further, in the method described in Patent Document 3, the shape of the powder having the metallic luster mixed with the resin component is not directional, and the shape of the powder having the metallic luster can be suppressed. The difference in the light reflection direction and the chromatic aberration are not prevented, and the difference in the surface gloss and the reflection state at the boundary between the resin merging portion and the merging portion of the resin of the molded article main material is not prevented. Patent Documents 1 to 5 In the case where the crystalline resin is injection-molded, the merging portion of the resin is flattened to eliminate the sag of the merging portion, which is the dissolved wire, but the trace of the merging = when the merging portion is visually confirmed (the boundary line) ) The appearance is poor but there is no ink, and there is no record of ways to eliminate such poor appearance (hereinafter referred to as "poor appearance"). The present invention has been completed by the above-mentioned facts, and an object of the present invention is to provide a mold for molding a crystalline resin by using a mold having a plurality of kiln mouths: injection molding can prevent the appearance of traces in the merging portion from being defective in appearance. law. [Technical means for solving the problem] 143359.doc 201111150 The special injection molding method of the present invention is characterized in that it uses a mold having a plurality of gates to mold a crystalline resin, and has a warp shape, and has: Heating the /JBL degree of the above-mentioned mold to a temperature of the above-mentioned crystalline resin, and θ 〗 , , , , 皿 皿 皿 皿 皿 皿 皿 皿 皿 ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; 结晶 结晶 结晶 结晶In the above-mentioned mold, the above-mentioned crystallized resin filled in the mold is formed by ejecting a step of filling the above-mentioned crystalline resin containing the spherical body with a plurality of gates. And the step of cooling the mold; and the spherical system, the spherical shape in the injection step and the cooling step can be substantially maintained. The injection molding method is a method of adding a spherical body to a crystalline resin to be molded, And heating the temperature of the mold at the time of injection molding to a temperature of 100 C or more of the melting degree of the crystalline resin. According to the results of the study by the inventors of the present application, according to the above-mentioned shot In the molding method, the crystalline resin is injection-molded by using a mold having a plurality of rinsings, and the trace remaining in the merging portion is prevented from being defective in appearance. The reason is that the spheroid included in the crystalline resin is injected and filled. When cooling and solidifying, the molecules to be aligned in the flow direction of the crystalline resin are solidified only along the surface of the spherical body of the equilateral shape in the vicinity of the surface of the spherical body, and as a result, the spherical system acts as a barrier along the crystalline resin. The molecularly oriented resisting body in the flow direction functions to suppress the alignment of the crystalline resin on both sides of the merging portion without causing a difference in gloss. It is also considered that, by the spheroid, the injection filling can be reduced. And the ratio of the molecules which are aligned in the flow direction of the crystalline resin during cooling and solidification, so that the anisotropy of the shrinkage ratio of the resin molded article can be alleviated, and the trace of the merging portion can be further lightened. 143359.doc 201111150 Degree added to the surname Γ The injection molding method is based on the temperature of the mold at the time of injection molding, the melting temperature of the resin, and the temperature above, so the temperature of the energy is increased. Printability is ensured and the heating time is shortened. 牟:" and the flowability of the resin that is shot out of the cavity can be appropriately maintained, thereby improving the transferability of the mold of the merging portion. The appearance of the mold is poor due to poor transfer. '[The injection molding H is preferably a microcapsule having thermal expansion property, and the mold is heated in the range of Τ1$Τ$Τ2. The temperature of the mold 'T1 is a temperature at which the microcapsules start to swell by the pressure reduction around the microcapsules, and τ2 is a transition point from a slow increase to a sharp increase in the temperature of the expansion of the microcapsules. By this, since the crystalline resin is strongly pressed against the mold at the time of expansion of the microcapsules, the transfer property of the mold of the merging portion can be further improved, and the residue of the merging portion can be more reliably prevented from being defective in appearance. Moreover, the foam of the foaming gas system in the chemical foaming agent is simple, so that when the bubble is exposed on the surface of the molded article, the temperature of the foaming gas is lowered due to the cracking of the bubble or the cooling of the wall surface of the mold. The bubble loses the expansion force. On the other hand, since the microcapsules are encapsulated in the shell without losing the expansion force due to foaming or the like, the microcapsules are cured and contracted by cooling of the mold. Since the periphery is decompressed, the expansion of the microcapsules is promoted, and the microcapsules are swollen and embedded in the region where the crystalline resin is shrunk. As a result, the resin region of the resin molecule can be reduced, so that the molecular orientation of the crystalline resin can be further suppressed, and the trace remaining in the merging portion can be more reliably prevented from being defective in appearance. 143359.doc 201111150 Furthermore, in the foaming gas system of the chemical foaming agent, the bubble is simple, so when the bubble is exposed on the surface of the molded article, the spherical shape of the bubble cannot be maintained due to cracking or deformation of the bubble. On the other hand, the shell of the microcapsule has sufficient rigidity and is less likely to be broken or deformed during injection molding. Therefore, the τ filling knife hinders the molecular alignment of the crystalline resin, and more reliably prevents the trace of the merging portion from remaining. . In the above injection molding method, the above crystalline resin may be an olefin resin. In the above-mentioned injection molding method, it is also effective to use an olefin-based resin which is generally used as a crystalline resin, and it is possible to prevent the appearance of defects in the merging portion from being defective in appearance, and to produce an olefin-based resin molded article having an excellent appearance. In the above injection molding method, the diameter of the spherical body is preferably 5 〇 μηη or more. By setting the diameter of the spheroid to be sufficiently larger than 50 μm of the molecular size of the crystalline resin, the area occupied by the crystalline resin in the resin molded article can be reduced, and the free volume of the molecule of the crystalline resin can be reduced (free region) ). Thereby, the molecular alignment in the flow direction of the crystalline resin during the injection filling and the cooling and solidification is further suppressed, so that it is possible to more reliably prevent the trace remaining in the merging portion from being defective in appearance. In addition, in the present specification, the "diameter" of the spheroid refers to the number average particle diameter of the spheroid, and in the case where the spheroid is a thermal expansion microcapsule, it means the average number of microcapsules after thermal expansion. Particle size. In the above injection molding method, the cooling of the mold is preferably carried out by flowing cooling water inside the mold. 143359.doc 201111150 By this, the production efficiency of the resin molded article can be improved by rapidly curing the resin after the injection is filled. [Effect of the Invention] According to the present invention, the crystalline resin is contained in a spherical shape, and the temperature of the mold at the time of injection molding is heated to a melting temperature of the crystalline resin _10 (temperature above rc) even if it is used in plural In the case where the mold of the gate is formed by injection molding of the crystalline resin, it is also possible to prevent the trace remaining in the merging portion from being defective in appearance. [Embodiment] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Fig. 1 shows the present embodiment. A cross-sectional view of an example of a mold used in the injection molding method of the embodiment. As shown in the figure, the mold cylinder includes a mold upper portion (movable mold) 10A and a mold lower portion (fixed mold) 10B. The mold 1 has a resin molded product. The mold hole 12 of the inverted shape and the gate 14 for filling the molten resin with the cavity 12 are shown. Fig. 1 shows an example in which the gate 14 also functions as a sprue (so-called direct washing). However, the type of the washing port 14 is not limited thereto. For example, the side gate of the resin may be injected from the side of the mold 1. The washing ports 14 (14A, 14B) are respectively provided in the example shown in Fig. 1. The two ends of the hole 12. Thus, when the filling resin is injected into the mold 1 having a plurality of flooding ports 14 (14, 14B), the resin 20 injected by the different gates 14 and 148 will be respectively shown in Fig. 1. The direction of the arrow flows, and the confluence in the cavity 12 merges. The inventor of the present application perceives that the mold having a plurality of gates 14 is used, 〇 143359.doc 201111150, . In the case of heating and cooling forming by injection molding, the merging portion 炼 of the smelting resin at the time of injection filling can be made flat, and the "L portion of the sag of the splicing line can be eliminated, but the merging portion is visually confirmed. The appearance of the resin molded article is poor. In the case of the injection molding method of the present embodiment, the details of the injection molding method of the present embodiment will be described later, in which the crystalline resin 2〇 to be molded contains a spherical body, and the mold 1 during injection molding is formed. Temperature plus The temperature to the melting temperature of the crystalline resin is 〇〇 〇〇 以上. According to the results of the study by the inventors of the present application, according to the injection molding method, even if a mold having a plurality of rinsings 14 is used, crystallization will occur. In the case where the resin 20 is formed by injection molding, it is possible to prevent the trace of the merging portion M from remaining as a defective appearance. The reason for this is that the spheroidal body contained in the crystalline resin 20 is required to be injected and filled and cooled and solidified. The molecule which is aligned in the flow direction of the crystalline resin will only solidify along the surface of the spherical body of the isotropic shape near the surface of the spherical body. As a result, the spherical system acts as a barrier along the crystalline resin 20. The molecularly oriented resisting body in the flow direction functions, and the alignment of the crystalline resin 20 on both sides of the merging portion is suppressed, so that there is no difference in gloss or reflection state. It is also determined that by the spheroid, The ratio of the molecules aligned along the flow direction of the crystalline resin 2〇 at the time of injection filling and cooling solidification can be reduced, so that the anisotropy of shrinkage of the resin molded article can be alleviated And more dilute marks the confluence of the Ministry of Μ. 143359.doc -10· 201111150 In the injection molding method, the temperature of the mold 10 at the time of injection molding is heated to a melting temperature of the crystalline resin 2 〇 (temperature of TC or more, so that the crystalline resin can be considered. The fluidity and the transferability are ensured, the temperature rise time is shortened, and the temperature rise energy is suppressed. Further, the IL material (softness) which is emitted to the cavity 12 of the cavity 12 can be appropriately increased, thereby improving the mold 1 of the merging portion μ. Therefore, it is possible to prevent the appearance defect caused by the transfer failure of the mold 1 of the merging portion. The injection molding method of the present embodiment will be described in detail below. The crystallizable resin 2 0 is a degree of crystallization. The olefin-based resin such as polyethylene (ruthenium) or polypropylene (ρρ) is preferable, and the injection molding method of the present embodiment is also effective for generally using an olefin-based resin which is a crystalline resin. It is possible to prevent the appearance of defects in the merging portion from being defective in appearance, and to produce an olefin-based resin molded article having an excellent appearance. The spherical body contained in the crystalline resin 20 is only substantially spherical. In particular, a spherical filler or a microcapsule of any material can be used. For example, as a spherical body, it is preferable to use a spherical body as described in Japanese Laid-Open Patent Publication No. Hei. No. Hei. A heat-expandable microcapsule having a structure in which a foaming agent (core) is contained in a shell, and the microcapsules which are thermally expandable as a spherical body are expanded by injection or after being filled and filled, and the crystalline resin is used. 2〇 is strongly extruded into the mold 10, so that the transferability of the mold 10 of the merging portion can be further improved, and the trace residue of the merging portion can be more reliably prevented from being defective in appearance. And the 'previous chemical foaming agent is emitted. Since the bubble system is a simple bubble, when the surface of the molded article is 143359.doc -11 · 201111150 ι, the temperature of the foaming gas is lowered due to the cracking of the bubble or the cooling of the wall surface of the mold. The bubble loses the expansion force'. In contrast, the microcapsules are not encapsulated in the shell due to the foaming gas system, and the expansion force is not lost due to foaming or the like. Therefore, the crystal: the resin 20 is cured and shrunk by the cooling of the mold 10. When the periphery of the microcapsules is depressurized, the expansion of the microcapsules can be promoted, and the microcapsules can be expanded to be buried in the contracted region of the crystalline resin. Thus, the resin region in which the resin molecules can be moved is reduced. Further, the molecular alignment of the crystalline resin 20 is further suppressed, and the trace residue of the merging portion is more reliably prevented from being defective in appearance. Further, since the chemical foaming agent has a simple bubble in the foaming gas system, the bubble is exposed to the molding. In the case of the surface of the product, the spherical shape of the bubble cannot be maintained due to cracking or deformation of the bubble, and the shell of the microcapsule has sufficient rigidity and is less likely to be broken or deformed during injection molding, so that it can be sufficiently hindered. The molecular alignment of the crystalline resin 2〇 furthermore prevents the trace of the merging portion of the river from being more reliably defective. Further, the spheroid may be of one type or a plurality of types may be used in combination. For example, a thermally expandable microcapsule may be added to the crystalline resin 2, and a spherical filler composed of metal particles, metal powder or glass particles, and glass frit may be added. In the case where both the heat-expandable microcapsules and the spherical filler including the metal particles, the metal powder, the glass particles, and the glass frit are added to the crystalline resin 20, it is possible to suppress the two previously combined with the confluent portion. A uniform appearance molded article having a poor appearance due to the alignment of the crystalline resin 20 on the side. Further, the diameter (number average particle diameter) of the spheroids added to the crystalline resin 20 is preferably 50 μm or more. Particularly in the case where the spheroid is a heat-expandable microcapsule 143359.doc 12 201111150, the diameter after expansion is preferably 50 μm or more. By setting the diameter of the spherical body to be substantially larger than 5 μm of the molecular size of the crystalline resin 20, the area occupied by the crystalline resin 20 in the resin molded article can be reduced, and the molecular weight of the crystalline resin 20 can be reduced. Volume (free area). In particular, the 'thermal expansion capsule can reduce the size of the free volume of the molten resin by expanding the size of the spherical body by expansion, and can suppress the melting by pressing the spherical shape on the molten resin by the pressure of the foaming gas. The alignment of the resin is aligned along the surface of the spheroid in a single direction of the molecule. Thereby, the molecular alignment along the flow direction of the crystalline resin 20 at the time of injection filling can be further suppressed, so that it is possible to more reliably prevent the trace remaining in the merging portion from being defective in appearance. The temperature of the mold 10 at the time of injection molding is heated to a melting temperature of the crystalline resin 2 T of Tm - 100 ° C or more. The temperature T of the mold 10 at the time of injection filling is heated to Tm-100g T幺Tm+50° from the viewpoint of ensuring the fluidity of the crystalline resin 2, ensuring the transferability, shortening the temperature rise time, and suppressing the temperature rise energy. The scope of C. The temperature T of the mold 10 is preferably Tm-100 C or more and Tm-100 ° C g Tg Tm + 50 ° C in the case where the spherical body is a microcapsule or not. In particular, when the spherical body is a microcapsule, the temperature T of the mold 设为 is set to be Tm-100° C. or more from the viewpoint of maintaining the spherical shape and surely hindering the alignment of the crystalline resin 20 (at Tm-l〇). 〇t gT$Tm+5〇t: is preferable, and the range set in T1STST2 is better, and the setting range is better. However, T1 is a temperature at which the microcapsules begin to swell by the decompression of the periphery of the microcapsules (crystalline resin 2 〇), and the degree of expansion deformation of the T2 system relative to the temperature of the microcapsules is gradually increased from a slow increase to a sharp inflection point temperature. Te is a temperature (> τ 1) at which the foaming agent inside the microcapsules 143359.doc 13·201111150 starts to swell due to decomposition and volatilization. For example, in the case of a microcapsule having an acrylonitrile-based shell, Τ1 is close to Te_70. (The value of T: is close to the value of Te + 30 ° C. Therefore, it is preferable to set the temperature T of the mold 1 于 to Te-70 ° CS TS Te + 30 ° C, and set it to Te $ TS Te + 30 Fig. 2 is a graph showing an example of the mold temperature and the resin pressure at the merging portion at the time of injection molding in the injection molding method of the embodiment. In the figure, the mold temperature at the time of injection filling is shown in the lower stage. In the graph, the resin pressure of the merging portion at the time of filling is shown in the upper graph. In the example shown in Fig. 2, the heating of the mold 10 is started at time t1, and the heating of the mold 10 is continued until the temperature of the mold 10 is continued. Τμαχ(Τπι_100°CS Τ) is reached (but Tm is the melting temperature of the crystalline resin 20). Thereafter, before the mold 10 is cooled (t<t4), the mold 10 is maintained at a temperature thereof. In the cavity 12 of the mold 1 of the temperature ,, the injection filling of the crystalline resin 20 is started (t=t2) via the plurality of windings 14 (14Α, 14Β). If the injection filling of the crystalline resin 20 is continued, At time t3, it is injected by different washing ports 14 (14A, 14B). The crystalline resin 20 is condensed at the merging portion, so that the resin pressure at the merging portion 开始 starts to rise. After the injection and filling of the crystalline resin 20 is performed, the mold 10 is cooled at the time t4, and the crystals solidified in the cavity 12 are solidified. Resin 20. From the viewpoint of rapidly curing the crystalline resin 2 ,, the cooling of the mold 1 is preferably carried out by flowing cooling water inside the mold 1 。. Finally, by curing the solidified crystalline resin 2 from the mold 1 〇 , , 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 143 结晶When the crystalline resin 20 containing the spherical body 22 is injected into the cavity 12 of the mold 10 shown in Fig. 3(a), the crystalline resin 20 injected from the different gates will be respectively directed into the cavity 12. The merging portion M flows (see Fig. 3(b)). Thereafter, as shown in Fig. 3(c), at the merging portion M, the flow front edges F of the crystalline resin 20 injected by the different gates are brought into contact with each other. The resin pressure of the junction M starts When the injection molding of the crystalline resin 20 is continued, the combination of the crystalline resin 20 of the merging portion M progresses (see Fig. 3(d)), and finally the transfer of the mold 1 of the merging portion is completed. According to the injection molding method of the present embodiment, the spherical resin 22 is contained in the crystalline resin 20 to be molded, and the temperature of the mold 10 at the time of injection molding is heated to the melting temperature of the crystalline resin 2〇. In addition, when the temperature is maintained after the above-mentioned heating, the crystal resin which is generally slow in crystallization rate of the biodegradable resin or the like is more effective. Therefore, the spherical body 22 contained in the crystalline resin 20 functions as a resister that hinders molecular alignment along the flow direction of the crystalline resin 2G at the time of injection filling and cooling solidification, and both sides of the merging portion M The degree of alignment of the crystalline resin bismuth is substantially the same as 'the difference in gloss. Further, since the spherical body 22 reduces the proportion of molecules aligned in the flow direction of the crystalline resin 20 at the time of injection filling and cooling solidification, the shrinkage ratio of the resin is reduced to 143359.doc 15 201111150 To the opposite sex, and more diminishing the traces of the confluence M. Especially in the case where the spheroid is a heat-expandable microcapsule, the foaming gas is surrounded by the shell of the microcapsule which is filled with rigidity, and there is little crack or deformation to maintain the spherical shape, thereby making the microcapsule The resistance of the molecular alignment is hindered, and the anisotropy of the shrinkage ratio of the resin molded article is alleviated, and the trace of the confluent portion is further reduced. In addition, since the temperature of the mold 1 at the time of injection molding is heated to a temperature equal to or higher than the melting temperature of the crystalline resin 20, the fluidity of the crystalline resin, the transferability, and the temperature rise time can be shortened. Further, the temperature rise energy is suppressed, and the fluidity (softness) of the resin which is ejected to the cavity 2 is appropriately maintained, thereby improving the transferability of the mold of the merging portion M. Therefore, the confluence can be prevented. The present invention is not limited to the above, and the present invention is not limited thereto, and various modifications and changes can be made without departing from the spirit and scope of the invention. [Examples] According to the method of the above-described embodiment, injection molding was carried out as follows, and the appearance of the resin molded article was evaluated. [Example 1] The mold 10 was crystallized using a mold for a front grille of a car having three gates 14 Polypropylene (pp, Japan Polypropylene Co., Ltd., Novatec-pp) having a melting temperature of 165 ° C was used as the resin 20, and 2 wt% of thermal expansion was added as a spheroid in the crystalline resin 20 Microcapsule (made by Sekisui Chemical Co., Ltd., ADVANCELL, after foaming _ 143359.doc •16· 201111150 Φ80~200 μηι, T1=9rc, T2 = 195t:, Te=i65^. The steam is applied as a heat medium fluid. The injection molding of the mold 10 of the crystalline resin 20 is carried out as follows using 450MEII-70DD manufactured by Mitsubishi Plastics Co., Ltd. First, the fluidity, the transferability, and the heating time are shortened. From the viewpoint of suppressing the temperature rise energy, the temperature of the mold 1〇 at the time of injection filling is previously heated to 120° C. In the mold cavity 12 of the mold 1 , the filled crystalline resin 20 is injected through the three gates 14 ^ In this case, the temperature of the crystalline resin 2 (i.e., the temperature of the cylinder of the injection molding machine) is set to 230 ° C. After the injection of the crystalline resin 20, the expansion of the microcapsules is promoted, and the pressure holding step is not performed. The mold 10 is cooled to cure the crystalline resin 20 in the cavity 12. Thereby, the resin molded article shown in Fig. 4 is obtained. In addition, this embodiment is to cool the mold 1 after the injection is filled, but to shorten the molding. In the meantime, it is also possible to start cooling before the completion of the injection filling. After the filling is completed, the right mold hole 12 is retracted by the movable mold plate (not shown) or the mold neutron hydraulic cylinder is retracted to expand the cavity 12, and no appearance defect can be obtained. The lightweight foamed molded article of the crystalline resin 20. In the present embodiment, the heating of the mold is carried out using steam as the heating medium fluid. However, not only the heating medium fluid but also the resistance heater can be used. Other heating means such as a frequency heater. [Embodiment 2] In this embodiment, polyethylene (PE) is used in place of polypropylene (PP), and the temperature of preheating of the mold 10 is set to 1 〇 (other than TC, The resin molded article was produced under the same conditions as in Example 1 of 143359.doc -17 201111150. Further, the melting temperature of the polyethylene (PE) used was 135 °C. [Comparative Example 1] A resin molded article was produced under the same conditions as in Example 1 except that the mold 20 was not subjected to preliminary heating at 120 °C. [Comparative Example 2] In the present comparative example, a spherical body was not added to the crystalline resin 20, and a pressure was applied at 45 MPa for 10 seconds after the injection was filled, and the resin was molded under the same conditions as in Example 1. Product. [Comparative Example 3] In the present comparative example, the addition of the spherical body to the crystalline resin 20 was carried out by injecting 0.5 wt% of supercritical nitrogen as a foaming agent into the crystalline resin 20, and the rest were A resin molded article was produced under the same conditions as in Example 1. [Comparative Example 4] In the present comparative example, a spheroid is added to the crystalline resin 2, and a chemical blowing agent (carbonated gas) in which 3 wt% of the masterbatch is mixed with the masterbatch 20 is used. A resin molded article was produced under the same conditions as in Example 以外 except that the foaming agent was molded. [Comparative Example 5] This comparative example was obtained by mixing aluminum powder of φ20 μηη as a spheroid in a crystalline resin, instead of microcapsules, and holding the pressure for 45 seconds for 10 seconds after the injection was filled. A resin molded article was produced under the same conditions as in Example 。. 143359.doc -18·201111150 [Comparative Study of Examples and Comparative Examples] The resin molded articles obtained in the above Examples 1 and 2 and Comparative Examples 1 to 5 were visually observed. Further, the results of the evaluation of the appearance of the resin molded article are shown in the following table. Table 1 - Appearance Evaluation Results of Resin Molded Articles \ Pre-heated resin spheroidal foaming agent merging part 模具 Traces (boundary line) Condensation recessed silver mark Example 1 ΡΡ Microcapsule microcapsules None 2 有ΡΕ Microcapsules Microcapsules None No Comparative Example 1 No ΡΡ Microcapsules Microcapsules have slight comparison Example 2 ΡΡ Nothing No No No Comparative Example 3 ΡΡ No supercritical gas (nitrogen) No or not Comparative Example 4 ΡΡ No chemical foaming agent (carbonated gas) No or no Comparative Example 5 ΡΡ Aluminium powder Nothing or not It is known from the table that the temperature of the mold 10 is heated to a melting temperature of the crystalline resin 20 at a temperature of -100 ° C or more due to injection filling. At the temperature, the crystalline resin 20 contains a spherical body, and the trace of the merging portion is not left to be defective in appearance (Examples 1 and 2). On the other hand, when the preliminary heating of the mold 10 was not performed (Comparative Example 1), or when the crystalline resin 20 did not contain a spheroid (Comparative Examples 2 to 4), and a spheroid containing a small diameter In the case (Comparative Example 5), although the 143359.doc -19-201111150 depression and silver mark of the merging portion can be prevented, the gloss of the surface of the resin molded article at the junction portion M and the difference in reflection state are caused. The trace (junction line) of the merging portion M remains as a defective appearance. [Cause of Appearance Failure in Comparative Example] The reason why the appearance defects were caused in Comparative Examples 1 to 5 will be described below with reference to Figs. Here, only the contents different from those of Fig. 3 described in the above embodiments will be described, and the description of the contents common to Fig. 3 will be omitted. Fig. 5 is a view showing a state in which the vicinity of the merging portion m is formed by injection molding under the conditions of Comparative Example. In the comparative example, since the preliminary heating of the mold is not performed, the extrusion of the crystalline resin 20 in the merging portion into the mold 1 is insufficient, so that the '纟a aa resin 20 is cured (see Fig. 5(d)). Therefore, the depression of the traces of the confluence portion is caused to be defective in appearance. Fig. 6 is a view showing a state in which the vicinity of the merging portion 射 at the time of injection molding under the conditions of Comparative Example 2. Since the preliminary heating of the mold was carried out in Comparative Example 2, it was possible to prevent the depression of the merging portion, the silver mark, and the transfer failure of the mold 1 (refer to Fig. 6(e)). However, since the crystalline resin 2 does not contain a spheroid in the comparative example 2, the crystalline resin 20 undergoes molecular alignment along the flow direction, resulting in a difference in the degree of alignment between the two sides of the merging portion. Poor gloss. Therefore, in the comparative example 2, the trace of the merging portion 残留 remains as an appearance defect (boundary line). Fig. 7 is a view showing a state in which the vicinity of the merging portion 射 at the time of injection molding under the conditions of Comparative Examples 3 and 4. Since Comparative Examples 3 and 4 performed the preliminary heating of the mold, it was possible to prevent the depression of the merging portion, the silver mark, and the transfer failure of the mold (see Fig. 7(e)). However, since Comparative Examples 3 and 4 did not cause the crystal tree 143359.doc -20- 201111150, the fat 20 contained a spheroid, the crystalline resin 20 was molecularly aligned along the flow direction, and the both sides of the confluence portion were produced. The difference in the degree of alignment is caused by the difference in gloss. Therefore, the traces of the merging portion μ in Comparative Examples 3 and 4 were left to be defective in appearance (boundary line). Further, in Comparative Examples 3 and 4, the crystalline resin 20 was foamed by using a supercritical gas, respectively. However, since the bubbles 24 are easily deformed by the pressure of the surrounding crystalline resin 20, it is particularly likely that bubbles are formed on the surface of the molded article. In this case, the spherical shape of the bubble cannot be maintained, and the molecular alignment of the crystalline resin 20 cannot be sufficiently hindered, and the difference in gloss and reflection state due to the difference in the degree of alignment between the both sides of the merging portion 产生 occurs. Fig. 8 is a view showing a state in which the vicinity of the merging portion μ at the time of injection molding under the conditions of Comparative Example 5. In Comparative Example 5, the temperature adjustment of the mold was performed, and the spherical aluminum powder was kneaded in the crystalline resin 20, so that the chromatic aberration of the sag of the merging portion and the transfer failure of the mold 10 can be suppressed (refer to FIG. 8). (Small. However, in Comparative Example 5, since the spheroid has a small diameter and does not expand due to thermal expansion, the spheroid has sufficient rigidity, but the molecular weight of the crystalline resin 20 cannot be sufficiently reduced. In the volume (free area), the crystalline resin (10) undergoes molecular alignment along the flow direction, and a gloss difference due to a difference in the degree of alignment of the crystalline resin 2〇 on both sides of the merging portion is generated. The boundary line is good. == Sectional view of the mold used in the method. - 2:: The temperature of the mold at the time of filling and the tree of the confluence part - 143359.doc -21 - 201111150 Fig. 3 (aHe) shows Fig. 4 is a view showing the shape of the automobile heat-dissipating thumb-shaped article of Example i and Example 2 by the injection molding method. Fig. 4 is a view showing a comparative example. 〗 conditions of the confluence of injection molding Fig. 6 (a) - (e) are views showing the state around the merging portion at the time of injection molding under the conditions of Comparative Example 2. Fig. 7 (a) - (e) are shown as comparative examples. 3 and 4 are diagrams showing the state around the merging portion at the time of injection molding. Fig. 8 (a) - (e) are diagrams showing the state around the merging portion at the time of injection molding under the conditions of Comparative Example 5. [Main component symbol Description 10 Mold 10A Mold upper part 10B Mold lower part 12 Mold hole 14 (14A) Washing port 14 (14B) Washing mouth 20 Crystalline resin 22 Spherical body 24 Bubble F Flow front Μ Confluence 143359.doc • 22-