200831266 九、發明說明 【發明所屬之技術領域】 本發明係有關於一種製備均勻微孔發泡體之方法及用 於彼之擠壓系統。更特別者爲本發明係有關於一種製備微 孔發泡體的方法，其包含將在擠壓機中塑化之熱塑性聚合 物樹脂與發泡劑混合，在將該混合物通經擠壓模之降壓區 期間熔融該混合物且在已熔融混合物中形成微孔隙，及在 φ 將該已熔融混合物通經擠壓模之冷卻區期間冷卻該形成時 具微孔隙之熔融混合物；以及一種可施行該方法的系統， 另包含設定在降壓區下游末端之溫度及在冷卻區上游末端 ' 之溫度使兩溫度之間爲3 0至20 0 之溫度差，藉此擠壓爲 微孔發泡體形式之混合物，及藉由拉擠單元以預定之發泡 體誘導比將自擠壓模擠出的微孔發泡體拉擠成型，藉此細 微地控制該微孔發泡體之發泡率和時間相依物理性質。本 發明亦有關於一種能夠施行該方法的系統。 【先前技術】 通常，發泡體具有絕熱性質、隔音性質、質輕、耐衝 擊性、電絕緣性質、光學特性等之許多優點。依此，此等 發泡體廣泛地在與隔音材料、絕緣材料、緩衝材料、耐震 材料、光反射板、光擴散板等有關的各種不同領域以各種 不同目的使用。 此等發泡體係使用發泡製程製備，例如聚合物樹脂經 機械發泡之製程或含有物理性發泡劑或化學性發泡劑的樹 200831266 脂化合物經擠壓模製以製備發泡體的製程。對於物理性發 泡劑，可使用二氧化碳、氮或氫氟碳。對於化學性發泡劑 ，可使用生成氣體之有機物質，例如偶氮二碳醯胺。 在該發泡製程中，最重要的是控制孔隙的大小、形狀 和數量分佈。該發泡製程相較於其他製程爲具有許多參數 且在控制條件上有困難。尤其，發泡體的性質可能相當地 取決於發泡體的發泡率。因此，發泡率的調整非常重要。 Φ 依慣例，發泡率的調整係經由發泡劑含量的調整或溫 度的調整來達成。然而，發泡率的調整是以非常廣偏離範 - 圍的單位（例如10%範圍，如10%、20%·..)槪略達成。爲此 • 理由，並不可能以狹窄偏離範圍的單位細微地達成發泡率 調整，所以在發泡體性質的調整或發泡體發泡率之均勻調 整會有所限制。 圖1爲說明於微孔發泡體製備中，施行一般擠壓和發 泡製程的擠壓和發泡系統示意圖。圖2爲經由放大的截面 • 和曲線圖來說明僅包括降壓區之習用擠壓模，且在擠壓模 中發生之溫度變化。 參照圖式，擠壓和發泡製程之施行係經由依擠壓產物 之前進方向以下示之順序排列：擠壓機1 0、擠壓模20、校 正單元30、拉擠單元40和分割器50。 爲了製備發泡體，用爲擠壓產物之原料與發泡劑由攪 拌器1 1混合。所產生的混合物在擠壓機1 0中熔融後經過擠 壓機1 〇擠出。爲了形成具有特定形狀之擠壓產物，該擠壓 模製材料通經組裝有外部加熱器22之擠壓模20。當擠壓模 200831266 製材料通經界定在擠壓模20內的降壓區21時發泡。因此’ 在高溫態的經發泡擠壓產物由擠壓模20擠出，經發泡擠壓 產物由擠壓模20以高溫態放出，然後爲了冷卻且固化該經 發泡擠壓產物而通經校正單元3 0以維持經發泡擠壓產物的 特性。已固化的產物在通經拉擠單元40之後由分割器50切 割成所需長度。因此，製得具有所需形狀的發泡體。 在高溫態由擠壓模20擠出之後進料至校正單元30之擠 壓產物在充分冷卻之前是以相當高溫狀態曝露於大氣壓。 爲此理由，該擠壓產物藉由其內在發泡壓力進行後發泡。 此外，該擠壓產物不僅於擠壓方向膨脹，亦於寬度方向膨 脹。結果，由於發泡體的發泡率隨經過時間而變化，嚴重 的問題爲所製得發泡體可能並非所需的發泡率，且可能具 有非均勻的截面形狀。 同時，上述擠壓/校正系統的校正單元30作用爲藉冷 凍劑循環器3 1循環冷凍劑以冷卻擠壓產物，其具有約3至6 m的非常長加工長度。爲此理由，因爲校正單元30造成很 大的空間限制。此外，當擠壓產物通經校正單元3 0時的擠 壓率爲約3至5 min/min。爲此理由，由於校正製程致使擠 壓產物在拉擠率增加上有所限制，造成生產力的大幅降低 〇 與製備微孔發泡體相關者，發泡體發泡率之調整技術 已揭示於：例如日本專利3 1 9 9 9 5 1號。此專利揭示一種製 備熱塑性彈性體之方法。該方法的事實基礎爲發泡量增加 係發生在增加之熔融延性是在可維持晶胞（由於空氣氣泡 200831266 成長而形成）壁面強度之範圍內，且包括測量含有熔融延 性增強劑之組成物之進料速率作爲熔融延性之製程、測量 該組合物發泡量之製程、及基於所測得之發泡量選用組成 物之組成及/或發泡溫度以得到所需發泡量之製程。 然而，上述技術限定在只使用水（H20)作爲發泡劑的 情況。亦即，該技術並不能應用在所擠壓模製之聚合物樹 脂對水不具有溶混性的情況。爲了獲得所需的發泡量，則 Φ 有必要藉由測量該組成物之熔融延性，同時改變組成物中 之構成元素含量而重複數次地實行發泡量調整。爲此理由 - ，得到所需發泡量的製程爲非常迂迴且複雜。此外，其需 ’ 使用另外的熔融延性測量裝置。除此之外，在生產效率上 會降低。其在細微地調整發泡溫度，及維持所需的溫度上 亦有困難。而且，其不可能阻止由擠壓模擠出的擠壓產物 在冷卻之前被後續發泡。因此，上述的技術具有許多問題 〇 # 同時，日本專利未審查公開1 997-057822號揭示一種 技術用於檢測發泡模與在發泡模內發泡之樹脂之間所生成 之磨擦力，及控制該樹脂之進料速率以避免由於擠壓模與 擠壓產物之間的磨擦力造成湧出，及因此製備具有均勻發 泡率與高尺寸準確性的發泡產物。 然而，雖然上述技術因爲可提供均勻的磨擦力而可製 備具有相當均勻發泡率的發泡體，其仍有無法細微地控制 發泡率的問題。 同時，雖然無關於發泡率之調整，韓國專利未審查公 -8- 200831266 開1999-0063 440號揭示一種技術用於製備具有大厚度與高 發泡量之發泡熱塑性樹脂片。依據該技術，其係使用一種 包括發泡區與冷卻區的擠壓模。該擠壓模爲了達到額外的 發泡，亦包括藉由密封構件維持所需之壓力降低程度的降 壓室，藉此得到具有高發泡率的發泡體。依據此技術，將 調整界定該降壓室的一對屏壁之間的空間。因此，其可能 避免空氣氣泡在該片狀物之寬度方向或垂直於該片狀物之 φ 厚度方向成長，藉此製備具有大厚度與高發泡量之發泡熱 塑性樹脂片。 然而，依據上述技術會產生溫和的溫度分佈，此係由 於發泡體區與冷卻區是相互接觸所致之熱傳導。爲此理由 ，該發泡體的密度降低，所以發泡體在接著的拉擠成型步 驟會容易改變截面形狀。爲調整降壓室之屏壁空間，需要 一額外的驅動單元。結果，該製備方法變得更複雜。此外 ，該擠壓產物由於額外之發泡致使物理性質劣化。 # 總而言之，所高度需求者爲提供一種發泡體之製備技 術，其能夠細微且均勻地控制發泡體的發泡率，致使該發 泡體不管經過時間均具有所需的發泡率，且所得到的擠壓 產物不管經過時間均具有所需截面形狀。 【發明內容】 本發明槪要 因此，本發明係爲解決上述之問題以及尙未解決之其 他技術問題。 200831266 在積極硏究和各種不同之重複實驗後，本案發明人發 現：當微孔發泡體在微孔發泡體之製備方法中經由擠壓模 擠出時，當設定在降壓區下游末端之溫度與在冷卻區上游 末端之溫度具有預定差値之條件下，且自擠壓模擠出之微 孔發泡體經由拉擠單元以預定之拉擠率拉擠成形，則可能 以數個百分率的單位細微地調整該發泡體之發泡率，且均 勻控制該發泡體之發泡率，致使該發泡體不管經過時間均 具有所需的發泡率，且所得到之擠壓產物不管經過時間均 具有所需的截面形狀。 較佳具體實例之詳細敘述 本發明提供一種製備微孔發泡體的方法，其包含將在 擠壓機中塑化之熱塑性聚合物樹脂與發泡劑混合，在將該 混合物通經擠壓模之降壓區期間熔融該混合物且在已熔融 混合物中形成微孔隙，及在將該已熔融混合物通經擠壓模 之冷卻區期間冷卻該形成時具微孔隙之熔融混合物，另包 含設定在降壓區下游末端之溫度及在冷卻區上游末端之溫 度使兩溫度之間爲3 0至200 °C之溫度差，藉此擠壓爲微孔 發泡體形式之混合物；及藉由拉擠單元以預定之發泡體誘 導比將自擠壓模擠出的微孔發泡體拉擠成型，藉此細微地 控制該微孔發泡體之發泡率和時間相依物理性質。 詳細而言，本發明之微孔發泡體製備方法包含：（a) 將在擠壓機中塑化之熱塑性聚合物樹脂與發泡劑混合， (b)在將該混合物通經擠壓模之降壓區期間熔融該混合物 -10- 200831266 且在已熔融混合物中形成微孔隙，（C)在將該已熔融混合 物通經擠壓模之冷卻區期間冷卻該形成時具微孔隙之熔融 混合物，及（d)藉由拉擠單元以預定之發泡體誘導比將自 擠壓模擠出的已冷卻微孔發泡體拉擠成型，藉此細微地控 制該微孔發泡體之發泡率和時間相依物理性質。 依據本發明之微孔發泡體製備方法，該發泡製程（即 形成微孔隙之製程（b))，及擠壓產物之固化製程（即亦稱爲 φ 發泡體之擠壓產物的冷卻製程（〇)係在擠壓模中完成。因 此，已發泡之產物在固化態擠壓時在其表面部分具有稠密 結構，此係由於該已發泡產物在擠壓時產生驟然溫度變化 。結果，當擠壓產物曝露於大氣壓時，該擠壓產物之寬度 方向並未發生膨脹。因此僅在擠壓方向經由拉擠單元之速 度控制來控制該發泡體之擠壓速度，即可能細微地調整該 發泡體的發泡率，且均勻地控制該發泡體的發泡率，致使 該發泡體不管經過時間均具有所需的發泡率。此外，在擠 • 壓產物由擠壓模擠出以進行習用之冷卻製程之前，可完全 避免後發泡現象的產生。 依據本發明，在降壓區下游末端之溫度及在冷卻區上 游末端之溫度之間爲30至200 °C之溫度差。較佳爲該溫度 差爲5 0至1 5 0 °C。 當溫度差爲低於3 0 °C時，在降壓區中形成的微孔隙會 繼續成長。爲此理由，已發泡產物不易具有足夠厚度的表 層。另一方面，當溫度差超過20 0 °C時，由於發泡體之驟 然固化作用而不易執行製造製程。 -11 - 200831266 降壓區與冷卻區均可在單一的擠壓模中界定。或者， 降壓區與冷卻區可分別地在分隔封閉類型之擠壓模中界定 。在前者情況下，其可有效率地控制微孔發泡體之微孔隙 形成，且可有效率地達到表層形成。在後者情況中，則有 必要強力地夾緊擠壓模，致使降壓區下游末端的壓力可維 持在與冷卻區相同。 較佳者，該擠壓模包括加熱器以避免降壓區下游末端 附近的溫度降低。加熱器可組裝在擠壓模的內部。或者， 加熱器可組裝在擠壓模的內部和外部。對加熱器並無限定 。例如一般的電子加熱器可作爲加熱器。 較佳者，擠壓模包括冷卻器以避免擠壓模上游末端附 近的溫度上升。與加熱器相似者，該冷卻器可組裝在擠壓 模的內部，或可組裝在擠壓模的內部和外部。對冷卻器並 無限定。例如冷凍劑可於其中流動之管線可作爲冷卻器。 若必要時可使用適當數量之額外加熱器和額外冷卻器 〇 在降壓區下游末端的溫度可依據欲擠壓之原料類型而 適當調整。此溫度較佳爲150至25 0°c。當在降壓區下游末 端之溫度低於1 5 0 °C時，則不易充分地形成微孔隙。另一 方面，當溫度高於250 °C時，則熱塑性樹脂可能降解且熱 塑性樹脂過度發泡。 在冷卻區上游末端的溫度可依據欲擠壓之原料類型而 適當調整。此溫度較佳爲150至25 (TC。當在降壓區下游末 端之溫度低於1 5 (TC時，則不易充分地形成微孔隙。另一 -12- 200831266 方面，當溫度高於250 °C時，則原料（即熱塑性樹脂）可能 降解且該熱塑性樹脂過度發泡。 較佳者，在冷卻區上游末端之溫度係維持在略高於欲 擠壓原料之熔點或軟化點。更佳者，此溫度爲4 0至1 5 0 °C 。當在冷卻區上游末端之溫度低於40 °C時，則產生驟然固 化。在此情況下，不易執行製造製程。另一方面，當溫度 高於1 5 0 °C時，在降壓區中形成的微孔隙甚至在冷卻區中 仍繼續成長。爲此理由，該發泡體不易具有足夠厚度的表 層。 較佳爲各個降壓區和冷卻區中的溫度變化爲± 5 °C之內 。更佳爲該溫度變化爲±2 °C之內。當溫度變化超過土 5 °C的 範圍，則不可能得到均勻之擠壓產物。在此情況下，擠壓 產物的機械性質劣化。 ^寸於形成微孔隙之已溶融混合物的移動速度並無特定 限制。就生產效率而言，該移動速度較佳爲爲〇. 5至2 0 m/min 〇 在本發明的一個較佳具體實例中，在降壓區與冷卻區 之間存有溫度轉換區。依下列式（1)計算，該溫度轉換區 在製程前進方向的溫度轉換率可爲2至40°C /mm。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a uniform microcellular foam and an extrusion system therefor. More particularly, the present invention relates to a method of preparing a microcellular foam comprising mixing a thermoplastic polymer resin plasticized in an extruder with a foaming agent, and passing the mixture through an extrusion die Melting the mixture during the depressurization zone and forming micropores in the molten mixture, and cooling the molten mixture having micropores during the formation of the molten mixture through the cooling zone of the extrusion die; and The system of the method further comprises setting a temperature at a downstream end of the depressurization zone and a temperature at an end of the upstream end of the cooling zone such that a temperature difference between the two temperatures is between 30 and 20, thereby being extruded into a microcellular foam form a mixture of the microporous foam extruded from the extrusion die by a pultrusion unit at a predetermined foam induction ratio, thereby finely controlling the expansion ratio of the microcellular foam and Time depends on physical properties. The invention also relates to a system capable of performing the method. [Prior Art] Generally, the foam has many advantages such as heat insulating properties, sound insulating properties, light weight, impact resistance, electrical insulating properties, optical properties and the like. Accordingly, these foams are widely used for various purposes in various fields related to sound insulating materials, insulating materials, cushioning materials, shock-resistant materials, light reflecting plates, light diffusing plates and the like. These foaming systems are prepared by a foaming process, such as a process in which a polymer resin is mechanically foamed or a tree containing a physical foaming agent or a chemical foaming agent, 200831266 lipid compound, which is extrusion molded to prepare a foam. Process. For physical foaming agents, carbon dioxide, nitrogen or hydrofluorocarbons can be used. For chemical blowing agents, organic gases that form gases, such as azodicarbonamide, can be used. In this foaming process, the most important is to control the size, shape and number distribution of the pores. This foaming process has many parameters compared to other processes and has difficulty in controlling conditions. In particular, the properties of the foam may depend considerably on the foaming rate of the foam. Therefore, the adjustment of the expansion ratio is very important. Φ Conventionally, the adjustment of the expansion ratio is achieved by adjusting the content of the blowing agent or adjusting the temperature. However, the adjustment of the expansion ratio is achieved in a very wide range of deviations from the range (e.g., 10% range, such as 10%, 20%, ..). For this reason, it is not possible to finely adjust the expansion ratio in units of narrow deviation range, so there is a limit to the adjustment of the properties of the foam or the uniform adjustment of the foaming rate of the foam. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic view showing an extrusion and foaming system for performing a general extrusion and foaming process in the preparation of a microcellular foam. Fig. 2 is a cross-sectional view and a graph showing an example of a conventional extrusion die including only a pressure-reduction zone, and a temperature change occurring in the extrusion die. Referring to the drawings, the execution of the extrusion and foaming processes is arranged in the order indicated by the advance direction of the extruded product: extruder 10, extrusion die 20, correction unit 30, pultrusion unit 40, and divider 50. . In order to prepare a foam, the raw material which is an extruded product is mixed with a foaming agent from the agitator 11. The resulting mixture was melted in an extruder 10 and then extruded through an extruder 1. In order to form an extruded product having a specific shape, the extruded molding material passes through an extrusion die 20 in which an external heater 22 is assembled. When the extrusion mold 200831266 material passes through the pressure reduction zone 21 defined in the extrusion die 20, it foams. Therefore, the foamed extruded product in a high temperature state is extruded by the extrusion die 20, and the foamed extruded product is discharged from the extrusion die 20 in a high temperature state, and then passed through in order to cool and solidify the foamed extruded product. The unit 30 is calibrated to maintain the characteristics of the foamed extruded product. The cured product is cut by the divider 50 to the desired length after passing through the pultrusion unit 40. Thus, a foam having a desired shape is obtained. The extruded product fed to the correction unit 30 after being extruded in the high temperature state by the extrusion die 20 is exposed to atmospheric pressure at a relatively high temperature before being sufficiently cooled. For this reason, the extruded product is post-foamed by its inherent foaming pressure. Further, the extruded product not only expands in the extrusion direction but also expands in the width direction. As a result, since the foaming rate of the foam varies with elapse of time, a serious problem is that the obtained foam may not be a desired foaming ratio and may have a non-uniform cross-sectional shape. At the same time, the correction unit 30 of the above extrusion/correction system functions to circulate the refrigerant by the refrigerant circulator 31 to cool the extruded product, which has a very long processing length of about 3 to 6 m. For this reason, the correction unit 30 causes a large space limitation. Further, the extrusion ratio when the extruded product passes through the correction unit 30 is about 3 to 5 min/min. For this reason, due to the correction process, the extrusion product is limited in the increase of the pultrusion rate, resulting in a significant decrease in productivity. In connection with the preparation of the microcellular foam, the foaming rate adjustment technique has been disclosed in: For example, Japanese Patent No. 3 1 9 9 9 1 . This patent discloses a method of making a thermoplastic elastomer. The factual basis of the method is that the increase in the amount of foaming occurs when the increased melt ductility is within the range of wall strength that maintains the unit cell (formed by the growth of air bubbles 200831266) and includes the measurement of the composition containing the melt ductility enhancer. The feed rate is used as a process for melt ductility, a process for measuring the amount of foaming of the composition, and a process for selecting the composition of the composition and/or the foaming temperature based on the measured amount of foaming to obtain a desired amount of foaming. However, the above technique is limited to the case where only water (H20) is used as the foaming agent. That is, the technique cannot be applied to the case where the extruded polymer resin is not miscible with water. In order to obtain the desired amount of foaming, it is necessary to carry out the foaming amount adjustment several times by measuring the melt ductility of the composition while changing the content of the constituent elements in the composition. For this reason - the process of obtaining the required amount of foaming is very roundabout and complicated. In addition, it is required to use an additional melt ductility measuring device. In addition, productivity will decrease. It is also difficult to finely adjust the foaming temperature and maintain the desired temperature. Moreover, it is impossible to prevent the extruded product extruded from the extrusion die from being subsequently foamed before cooling. Therefore, the above-mentioned technique has many problems. Meanwhile, Japanese Patent Laid-Open Publication No. Hei No. Hei No. Hei No. Hei. No. Hei. No. Hei. No. Hei. The feed rate of the resin is controlled to avoid gushing due to the frictional force between the extrusion die and the extruded product, and thus a foamed product having a uniform foaming ratio and high dimensional accuracy is prepared. However, although the above technique can produce a foam having a relatively uniform expansion ratio because it can provide a uniform frictional force, there is still a problem that the foaming rate cannot be finely controlled. Meanwhile, although there is no adjustment regarding the expansion ratio, a technique for producing a foamed thermoplastic resin sheet having a large thickness and a high foaming amount is disclosed in Korean Patent Unexamined Publication No. Hei. No. Hei. No. Hei. According to this technique, an extrusion die including a foaming zone and a cooling zone is used. In order to achieve additional foaming, the extrusion die also includes a pressure reducing chamber which maintains a desired degree of pressure reduction by a sealing member, thereby obtaining a foam having a high expansion ratio. According to this technique, the space between the pair of screen walls defining the pressure reducing chamber will be adjusted. Therefore, it is possible to prevent air bubbles from growing in the width direction of the sheet or perpendicular to the thickness direction of the sheet, thereby preparing a foamed thermoplastic resin sheet having a large thickness and a high foaming amount. However, according to the above technique, a mild temperature distribution is produced due to the heat conduction caused by the contact between the foam region and the cooling region. For this reason, the density of the foam is lowered, so that the foam can easily change the cross-sectional shape in the subsequent pultrusion step. In order to adjust the wall space of the buck chamber, an additional drive unit is required. As a result, the preparation method becomes more complicated. In addition, the extruded product deteriorates physical properties due to additional foaming. In summary, it is highly desirable to provide a foam preparation technique capable of finely and uniformly controlling the foaming rate of the foam so that the foam has a desired foaming rate regardless of elapsed time, and The resulting extruded product has the desired cross-sectional shape regardless of the elapsed time. SUMMARY OF THE INVENTION The present invention is therefore to solve the above problems and other technical problems that have not been solved. 200831266 After active research and various repeated experiments, the inventors of the present invention found that when the microcellular foam is extruded through an extrusion die in the preparation method of the microcellular foam, when it is set at the downstream end of the pressure reduction zone The temperature is a predetermined difference from the temperature at the upstream end of the cooling zone, and the microcellular foam extruded from the extrusion die is drawn by a pultrusion ratio at a predetermined pultrusion rate, and may be several The unit of percentage finely adjusts the foaming rate of the foam, and uniformly controls the foaming rate of the foam, so that the foam has a desired foaming ratio regardless of elapsed time, and the obtained extrusion is obtained. The product has the desired cross-sectional shape regardless of elapsed time. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention provides a method of preparing a microcellular foam comprising mixing a thermoplastic polymer resin plasticized in an extruder with a foaming agent, and passing the mixture through an extrusion die Melting the mixture during the depressurization zone and forming micropores in the molten mixture, and cooling the molten mixture having micropores during formation of the molten mixture through the cooling zone of the extrusion die, further comprising setting The temperature at the downstream end of the nip and the temperature at the upstream end of the cooling zone are such that a temperature difference between the two temperatures is between 30 and 200 ° C, thereby being extruded into a mixture in the form of a microcellular foam; and by means of a pultruding unit The microcellular foam extruded from the extrusion die is pultrusion at a predetermined foam induction ratio, whereby the expansion ratio and time-dependent physical properties of the microcellular foam are finely controlled. In detail, the method for producing a microcellular foam of the present invention comprises: (a) mixing a thermoplastic polymer resin plasticized in an extruder with a foaming agent, and (b) passing the mixture through an extrusion die. Melting the mixture during the depressurization zone -10- 200831266 and forming micropores in the molten mixture, (C) cooling the molten mixture having microvoids during formation of the molten mixture through the cooling zone of the extrusion die And (d) pultrusion of the cooled microporous foam extruded from the extrusion die by a pultrusion unit at a predetermined foam induction ratio, thereby finely controlling the hair of the microcellular foam The bubble rate and time depend on the physical properties. According to the method for preparing a microcellular foam of the present invention, the foaming process (i.e., the process (b) for forming micropores), and the curing process of the extruded product (i.e., cooling of the extruded product also referred to as φ foam) The process (〇) is carried out in an extrusion die. Therefore, the foamed product has a dense structure on its surface portion when extruded in a cured state, because the foamed product undergoes a sudden temperature change upon extrusion. As a result, when the extruded product is exposed to atmospheric pressure, the width direction of the extruded product does not expand. Therefore, the extrusion speed of the foam is controlled only by the speed control of the pultrusion unit in the extrusion direction, that is, it may be subtle. The foaming rate of the foam is adjusted, and the foaming rate of the foam is uniformly controlled so that the foam has a desired foaming ratio regardless of elapsed time. The post-foaming phenomenon can be completely avoided before the compression molding is carried out for the conventional cooling process. According to the present invention, the temperature between the downstream end of the depressurization zone and the temperature at the upstream end of the cooling zone is 30 to 200 °C. The temperature difference. Preferably, the temperature difference is from 50 to 150 ° C. When the temperature difference is lower than 30 ° C, the micropores formed in the depressurization zone continue to grow. For this reason, the foamed product is not easily On the other hand, when the temperature difference exceeds 20 ° C, the manufacturing process is not easy due to the sudden solidification of the foam. -11 - 200831266 Both the pressure reduction zone and the cooling zone can be in a single extrusion Or defined in the mold. Alternatively, the pressure reduction zone and the cooling zone may be respectively defined in an extrusion die of a separate closed type. In the former case, it can efficiently control the formation of micropores of the microcellular foam, and may have The formation of the skin layer is efficiently achieved. In the latter case, it is necessary to strongly clamp the extrusion die so that the pressure at the downstream end of the pressure-reduction zone can be maintained at the same level as the cooling zone. Preferably, the extrusion die includes a heater Avoid temperature drop near the downstream end of the depressurization zone. The heater can be assembled inside the extrusion die. Alternatively, the heater can be assembled inside and outside the extrusion die. There is no limit to the heater. For example, a general electric heater Can be used as heating Preferably, the extrusion die comprises a cooler to avoid temperature rise near the upstream end of the extrusion die. Similar to the heater, the cooler can be assembled inside the extrusion die or can be assembled inside the extrusion die. And the outside. There is no limit to the cooler. For example, the pipeline in which the refrigerant can flow can be used as a cooler. If necessary, an appropriate number of additional heaters and additional coolers can be used, and the temperature at the downstream end of the pressure-reduction zone can be based on The type of the material to be extruded is appropriately adjusted. This temperature is preferably 150 to 250 ° C. When the temperature at the downstream end of the depressurization zone is lower than 150 ° C, microporosity is not sufficiently formed. On the other hand, when the temperature is higher than 250 ° C, the thermoplastic resin may be degraded and the thermoplastic resin is excessively foamed. The temperature at the upstream end of the cooling zone may be appropriately adjusted depending on the type of the material to be extruded. This temperature is preferably 150 to 25 (TC. When the temperature at the downstream end of the depressurization zone is lower than 15 (TC, it is not easy to form micropores sufficiently. Another -12-200831266, when the temperature is higher than 250 °) When C, the raw material (i.e., thermoplastic resin) may be degraded and the thermoplastic resin is excessively foamed. Preferably, the temperature at the upstream end of the cooling zone is maintained at a temperature slightly higher than the melting point or softening point of the material to be extruded. This temperature is 40 to 150 ° C. When the temperature at the upstream end of the cooling zone is lower than 40 ° C, sudden solidification occurs. In this case, the manufacturing process is not easy to perform. On the other hand, when the temperature is high At 150 ° C, the micropores formed in the depressurization zone continue to grow even in the cooling zone. For this reason, the foam does not easily have a surface layer of sufficient thickness. Preferably, each depressurization zone and cooling The temperature change in the zone is within ± 5 ° C. More preferably, the temperature change is within ± 2 ° C. When the temperature changes beyond the range of 5 ° C, it is impossible to obtain a uniform extruded product. In the case, the mechanical properties of the extruded product deteriorate. The moving speed of the melted mixture of the gap is not particularly limited. In terms of production efficiency, the moving speed is preferably 〇. 5 to 20 m/min. In a preferred embodiment of the present invention, the pressure is lowered. There is a temperature conversion zone between the zone and the cooling zone. According to the following formula (1), the temperature conversion zone of the temperature conversion zone in the forward direction of the process may be 2 to 40 ° C / mm.
Tl = (Τη- Tc)/L (1) 於式（1)中，「TL」代表溫度轉換率，「TH」代表在 降壓區下游末端之溫度，「Tc」代表在冷卻區上游之溫度 -13- 200831266 ’及「L」代表溫度轉換區的長度。 於本文中「溫度轉換區」意指在降壓區和冷卻區之間 發生驟然溫度變化的區域。此溫度轉換區用爲避免降壓區 和冷卻區之間發生熱交換。於本說明書中，發生在製程前 進方向之溫度轉換區內的溫度轉換稱之爲「溫度轉換率」 〇 當溫度轉換區具有更高溫度轉換率時，擠壓產物可在 φ 較高密度下固化。因此在製備具有極佳表面特性的擠壓產 物時，更有效者爲該溫度轉換區具有較高的溫度轉換率。 當溫度轉換率低於2 °C /mm時，並不可能控制在冷卻區中 微孔隙之形成。 當溫度轉換區的長度降低，則產生驟然溫度變化。因 此，較佳爲該溫度轉換區的長度爲1至150 mm。 當溫度轉換區的長度超過150 mm時，在降壓區和冷 卻區之間產生的溫度轉換很溫和，藉此造成擠壓產物的緩 # 慢固化。在這情況下，擠壓產物的密度爲並不想要的低。 同時，在降壓區和冷卻區均包含在擠壓模中的情況時 ，則可能將溫度轉換區的長度最小化而更有效率。 依據本的發明，在製程（d)之藉由拉擠單元以預定之 發泡體誘導比將微孔發泡體拉擠成型而細微地控制該微孔 發泡體之發泡率和時間相依物理性質中，其可藉由在細微 範圍內之單位調整拉擠單元的直線速度來調整該發泡體誘 導比。其中「細微範圍」意爲相當於1〇單位（例如1%之單 位）或更低的範圍。因此，當適當地設定發泡體誘導比時 -14- 200831266 ，便可製備具有所需發泡率在可容許誤差範圍的微孔發泡 體。 在一個較佳具體實例中，發泡率可調整在〇至80%的 控制範圍內。在製得之最終發泡體中，發泡率的可溶許誤 差範圍相較於所需的發泡率可爲±0.5 %或更低。 因此，其可在非常廣的發泡率調整範圍內準確地調整 發泡率。依此，本發明可用於調整發泡體的物理性質，廣 泛地使用在有必要細微且均勻地控制發泡體之發泡率的領 域中。 較佳者，發泡率變化以0.1至1.0%的經過時間產生。 因此，依據本發明方法製備的發泡體顯現出隨經過時間時 未有或極小之發泡率變化產生。依此，不管經過時間均可 維持該擠壓產物之截面形狀。因爲發泡體具有均勻的發泡 率，其可具有非常均勻的物理性質。 只要熱塑性聚合物樹脂爲可擠壓，則在熱塑性聚合物 樹脂方面並沒有特定限制。對於熱塑性聚合物樹脂，可使 用聚乙烯、丙烯酸樹脂、氯化乙烯樹脂、乙酸乙烯酯樹脂 、乙烯基乙醯樹脂、聚醯胺樹脂、或賽璐珞樹脂。較佳爲 該熱塑性聚合物樹脂包括一或多個選自丙烯基-丁二烯-苯 乙烯（ABS)共聚物、聚碳酸酯（PC)、聚氯乙烯（PVC)、聚苯 乙烯（PS)、聚甲基丙烯酸甲酯（PMMA)、聚酯、聚丙烯和 尼龍之聚合物。 在發泡劑方面並無特定限制，例如惰性氣體可使用爲 發泡劑。較佳爲使用二氧化碳氣體、氮或彼等之混合物爲 -15- 200831266 發泡劑。較佳爲3至0.1重量％之發泡劑與97至99.9重量％之 熱塑性樹脂混合。當發泡劑數量低於0· 1重量％時，在降壓 區中生成之發泡並不充分。因此在此情況下並不可能形成 微孔隙。另一方面，當發泡劑數量高於3重量％時，會有 不溶於熱塑性樹脂的殘餘發泡劑。 尤其，有必要在超臨界態下將發泡劑與熱塑性樹脂混 合。當發泡劑在超臨界態下與聚合物樹脂混合時，其對聚 φ 合物樹脂顯現出提高溶混性。因此在此情況時可能在樹脂 中可形成均勻孔隙、降低孔隙大小、及增加孔隙密度。對 於發泡劑，可使用已在超臨界態之發泡劑。或者，發泡劑 可在置入擠壓機後改變成爲超臨界態。 本發明亦提供一種擠壓和發泡系統，其包含用於塑化 熱塑性聚合物和如上文所述發泡劑之混合物以擠壓發泡體 之擠壓機，用於在預定速度下拉擠成型該經擠壓發泡體之 拉擠單元，及用於將經擠壓發泡體切割成具有特定長度之 • 塊狀物之分割器，其中該擠壓機包括一擠壓模，其具有降 壓區及與該降壓區相接的冷卻區，在降壓區下游末端之溫 度及在冷卻區上游末端之溫度被設定成兩溫度之間爲30至 2〇〇 °C之溫度差使該擠壓模足以擠壓出微孔發泡體，及拉 擠單元具有依據發泡體誘導比設定之拉擠速度以細微地控 制該微孔發泡體之發泡率和時間相依物理性質。 依據上述結構，本發明之擠壓和發泡系統可冷卻和固 化發泡體且同時擠壓該發泡體。因此可達到提高之擠出率 。其可省略校正單元或僅在最小加工長度下使用校正單元 -16- 200831266 ，因此減少系統的空間浪費。此外可達到降低製造成本和 大幅提高生產效率。 本發明之擠壓和發泡系統中，如上文所述之在降壓區 下游末端之溫度及在冷卻區上游末端之溫度被設定成兩溫 度之間爲30至200 °C之溫度差。由於此種驟然溫度差，擠 壓產物的表面能以密集態穩定地固化。結果，即使在擠壓 產物的中央部位有未固化部分，該擠壓產物仍未形變。因 Φ 此並無必要將擠壓產物通經校正單元。 在一個較佳具體實例中，具有短加工長度之校正單元 可選擇性地裝配在擠壓機和拉擠單元之間。 亦即，當有必要對已在冷卻區固化之擠壓產物施予額 外之冷卻及固化時，則可選擇性地組裝該系統使擠壓產物 通經校正單元。該校正單元係裝置成具有相當短的加工長 度。例如，該校正單元具有3 m或更低之加工長度，其係 短於習用校正單元的加工長度（即3至6 m)。較佳爲該校正 # 單元具有2 m或更低之加工長度。 本發明亦提供一種依據上述方法製得之微孔熱塑性樹 脂發泡體。 本發明微孔發泡體之較佳例子爲具有之結構包括比一 般微孔發泡體更厚的表層，及形成時具微孔隙之核心層， 如於韓國專利申請案2005- 1 1 563 7號所揭示者。該申請案 內容係納於本說明書用以參考。 因此，本發明微孔發泡體可使用於建築物之內部和外 部材料或使用於顯示裝置之光學反射板。尤其，該微孔發 -17- 200831266 泡體適用於建築物之內部和外部材料。更尤其是該微孔發 泡體適用於例如隔音材料、絕緣材料、建築材料、輕質結 構材料、包裝材料、電絕緣材料、緩衝材料、或耐震材^ 之建築物內部和外部材料。 下文中，本發明將參照圖示更詳細地敘述。當然，本 發明並未限定在下列之敘述。 圖3爲δ兌明於本發明具體實例中，在微孔發泡體製備 • 時施行擠壓和發泡製程的擠壓和發泡系統示意圖。圖4爲 經由放大的截面和曲線圖來說明本發明具體實例中包括擠 壓和發泡系統之擒壓模’且在擠壓模中發生之溫度變化。 如圖3和4所示，依據本發明方法，擠壓製程係經由擠 壓系統施行’其中擠壓機100、擠壓模200、拉擠單元400 和分割器5 0 0依擠壓產物之·前進方向以所述順序排列。 詳細言之，熱塑性樹脂利用攪拌器1 1 〇與發泡劑混合 ，所產生的混合物在通經擠壓機1 0 0期間塑化。所得到之 # 經塑化材料於熔融態中擠出。經擠壓產物進料至擠壓模 200，致使具有特定形狀。當經擠壓產物經由噴頭210通經 裝置有內加熱器220之擠壓模200的降壓區205時，微孔隙 在擠壓產物中形成。固化後該經擠壓產物由擠壓模200排 出，依序地通經包括在擠壓模200內的溫度轉換區27〇和冷 卻區260。該溫度轉換區270具有驟然溫度轉換率。在冷卻 區260內部裝置有冷卻器230。在特定拉擠速度下通經拉擠 單元400之後，經擠壓產物利用分割器500切割成所需長度 。因此，製得所需之擠壓產物。拉擠單元400的拉擠速度 -18- 200831266 係依據所需之發泡體誘導比設定。 因爲由擠壓模200擠出之擠壓產物是在冷卻且固化態 ，且設定在降壓區下游末端的溫度和在冷卻區上游末端的 溫度使兩溫度之間的溫度差爲30至200°C，當擠壓產物通 經溫度轉換區270時則依據驟然溫度轉換率形成具有密集 表層結構的發泡體。因此，即使當擠壓產物曝露於大氣壓 ，在擠壓產物的寬度方向並未膨脹。結果，依據拉擠單元 φ 400的拉擠速度調整而可控制該擠壓系統以具有所需之發 泡體誘導比。因此，其可藉此細微地調整該發泡體之發泡 率且均勻地控制該發泡體之發泡率，致使該發泡體不管經 過時間均具有所需的發泡率。其亦可製備不管經過時間均 可具有所需截面形狀的發泡體。 當有必要額外冷卻且固化該擠壓產物時，可將校正單 元3 00裝置於擠壓模200與拉擠單元400之間。在此情況下 ，擠壓產物由冷卻區260擠出以通過校正單元3 00。校正單 # 元3 00較佳具有約2 m或更低之加工長度。 因此便可避免擠壓系統的空間浪費且降低製造成本。 由於加工長度的降低，擠壓速度可增加。結果使生產力大 幅提高。 同時，冷凍劑循環器310與擠壓模200之冷卻區260及/ 或校正單元300相連接。因此，由於冷凍劑的循環而使擠 壓產物冷卻且固化。 【實施方式】 -19- 200831266 於下文中，將僅以說明之目的由實施例敘述本發明， 但本發明的範圍並不侷限於該等實施例。 [實施例1至4] 準備用於擠壓模製熱塑性樹脂之擠壓裝置：其係組裝 擠壓模（具有之整體結構係由溫度可控制高溫模作爲發泡 區組成），溫度轉換區，及低溫模（作爲雙軸擠壓機之冷卻 區）連同轉接器。在此情況，高溫模具有125 mm之長度， 溫度轉換區具有2 7 mm之長度，且低溫模具有4 0 mm之長 度。 將98重量份之硬質聚氯乙烯（PVC)化合物（由LG化學 品公司製造）置入擠壓機而完全塑化PVC。之後，使用高 壓泵將2重量份之氮置入擠壓機之桶柱內。因此單相混合 物經由模製以製造具有2 mm厚度與100 mm寬度之PVC 片。 設定擠壓機的條件使該桶柱的溫度依序爲190 °C -180 °C · 1 7 5 °C之變化。同時該轉接器維持在1 3 0 °C之溫度。高 溫模、溫度轉變區、及低溫模之條件述於下列表1。 [比較實施例1] 以與實施例1相同的方式製造PVC片，除了習用擠壓 模，其僅包括高溫模而未包括擠壓模（具有之整體結構係 由溫度可控制高溫模作爲發泡區組成）、溫度轉換區 '及 低溫模（作爲冷卻區）’且冷卻製程係使用具有約4 m長度 -20- 200831266 之校正單元實行。高溫模的條件述於下列表1 0 [實驗實施例1] 測量上述實施例1至4和比較實施例1之p v C片擠壓製 程的擠壓速度。測量結果述於表1。 <表1> 桶柱溫度(。〇 模溫度ΓΟ 擠壓 產物 溫度 CC) 直線擠 壓速度 (m/min) 發泡體 誘導比 (%) Cy 1 Cy 2 Cy 3 Cy 4 Ad HT模 LT模 1 2 1 2 實施例1 190 180 180 180 3.0 130 185 185 30 20 10 3.0 0.0 實施例2 190 180 180 180 3.8 130 185 185 30 20 43 3.8 21.1 實施例3 190 180 180 180 7.0 130 185 185 30 20 51 7.0 57.1 實施例4 190 180 180 180 11.2 130 185 185 30 20 62 11.2 73.2 比較實 施例1 190 180 180 180 7.0 130 185 185 於] 加 185 熱 180 7.0 21.1Tl = (Τη- Tc)/L (1) In the formula (1), "TL" represents the temperature conversion rate, "TH" represents the temperature at the downstream end of the depressurization zone, and "Tc" represents the temperature upstream of the cooling zone. -13- 200831266 'and 'L' represent the length of the temperature conversion zone. As used herein, "temperature conversion zone" means the zone where a sudden temperature change occurs between the pressure reduction zone and the cooling zone. This temperature conversion zone is used to avoid heat exchange between the depressurization zone and the cooling zone. In this specification, the temperature conversion occurring in the temperature conversion zone in the direction in which the process advances is referred to as the "temperature conversion rate". When the temperature conversion zone has a higher temperature conversion rate, the extruded product can be cured at a higher density of φ. . Therefore, in the preparation of an extruded product having excellent surface characteristics, it is more effective that the temperature conversion zone has a higher temperature conversion rate. When the temperature conversion rate is lower than 2 °C / mm, it is impossible to control the formation of micropores in the cooling zone. When the length of the temperature conversion zone is reduced, a sudden temperature change is produced. Therefore, it is preferred that the temperature conversion zone has a length of 1 to 150 mm. When the length of the temperature conversion zone exceeds 150 mm, the temperature transition between the depressurization zone and the cooling zone is mild, thereby causing slow curing of the extruded product. In this case, the density of the extruded product is undesirably low. At the same time, when both the depressurization zone and the cooling zone are included in the extrusion die, it is possible to minimize the length of the temperature conversion zone and be more efficient. According to the invention, in the process (d), the microcellular foam is pultrusion-molded by a pultrusion unit at a predetermined foam induction ratio to finely control the expansion ratio and time dependence of the microcellular foam. Among physical properties, the foam induction ratio can be adjusted by adjusting the linear velocity of the pultrusion unit in units within a fine range. The "fine range" means a range equivalent to 1 unit (for example, 1% unit) or lower. Therefore, when the foam induction ratio is appropriately set -14 to 200831266, a microcellular foam having a desired foaming ratio within an allowable error range can be prepared. In a preferred embodiment, the rate of expansion can be adjusted to within the control range of 〇 to 80%. In the final foam obtained, the soluble error range of the expansion ratio may be ±0.5% or less as compared with the desired expansion ratio. Therefore, it can accurately adjust the expansion ratio within a very wide range of expansion ratio adjustment. Accordingly, the present invention can be used to adjust the physical properties of the foam, and is widely used in the field where it is necessary to finely and uniformly control the foaming rate of the foam. Preferably, the change in the expansion ratio is produced with an elapsed time of 0.1 to 1.0%. Therefore, the foam prepared by the method of the present invention exhibits a change in the rate of expansion which is not or extremely small as time elapses. Accordingly, the cross-sectional shape of the extruded product can be maintained regardless of the elapsed time. Since the foam has a uniform expansion ratio, it can have very uniform physical properties. There is no particular limitation on the thermoplastic polymer resin as long as the thermoplastic polymer resin is squeezable. For the thermoplastic polymer resin, polyethylene, acrylic resin, vinyl chloride resin, vinyl acetate resin, vinyl acetal resin, polyamide resin, or cellophane resin can be used. Preferably, the thermoplastic polymer resin comprises one or more selected from the group consisting of propylene-butadiene-styrene (ABS) copolymers, polycarbonate (PC), polyvinyl chloride (PVC), and polystyrene (PS). , Polymethyl methacrylate (PMMA), polyester, polypropylene and nylon polymers. There is no particular limitation on the blowing agent, and for example, an inert gas can be used as a blowing agent. Preferably, carbon dioxide gas, nitrogen or a mixture thereof is used as a blowing agent -15-200831266. Preferably, 3 to 0.1% by weight of the blowing agent is mixed with 97 to 99.9% by weight of the thermoplastic resin. When the amount of the foaming agent is less than 0.1% by weight, the foaming generated in the pressure-reducing zone is not sufficient. Therefore, it is impossible to form micropores in this case. On the other hand, when the amount of the foaming agent is more than 3% by weight, there is a residual blowing agent which is insoluble in the thermoplastic resin. In particular, it is necessary to mix a blowing agent with a thermoplastic resin in a supercritical state. When the blowing agent is mixed with the polymer resin in a supercritical state, it exhibits an improved miscibility with the poly φ compound resin. Therefore, in this case, it is possible to form uniform pores in the resin, reduce the pore size, and increase the pore density. For the blowing agent, a blowing agent which has been in a supercritical state can be used. Alternatively, the blowing agent can be changed to a supercritical state after being placed in the extruder. The present invention also provides an extrusion and foaming system comprising an extruder for plasticizing a mixture of a thermoplastic polymer and a blowing agent as described above to extrude a foam for pull-down at a predetermined speed a pultrusion unit of the extruded foam, and a divider for cutting the extruded foam into a block having a specific length, wherein the extruder comprises an extrusion die having a lowering The nip and the cooling zone connected to the pressure reduction zone, the temperature at the downstream end of the pressure reduction zone and the temperature at the upstream end of the cooling zone are set to a temperature difference of 30 to 2 ° C between the two temperatures to cause the extrusion The stamper is sufficient to extrude the microcellular foam, and the pultrusion unit has a pultrusion speed set according to the foam induction ratio to finely control the foaming rate and time-dependent physical properties of the microcellular foam. According to the above structure, the extrusion and foaming system of the present invention can cool and solidify the foam while pressing the foam. Therefore, an increased extrusion rate can be achieved. It can omit the correction unit or use the correction unit -16-200831266 only for the minimum machining length, thus reducing the wasted space of the system. In addition, it can reduce manufacturing costs and greatly increase production efficiency. In the extrusion and foaming system of the present invention, the temperature at the downstream end of the pressure-reduction zone and the temperature at the upstream end of the cooling zone as described above are set to a temperature difference of 30 to 200 °C between the two temperatures. Due to this sudden temperature difference, the surface of the extruded product can be stably solidified in a dense state. As a result, even if there is an uncured portion in the central portion of the extruded product, the extruded product is not deformed. Because of Φ, it is not necessary to pass the extruded product through the correction unit. In a preferred embodiment, a correction unit having a short processing length is selectively mountable between the extruder and the pultrusion unit. That is, when it is necessary to apply additional cooling and solidification to the extruded product which has been solidified in the cooling zone, the system can be selectively assembled to pass the extruded product through the correction unit. The correction unit is configured to have a relatively short processing length. For example, the correction unit has a processing length of 3 m or less which is shorter than the processing length of the conventional correction unit (i.e., 3 to 6 m). Preferably, the correction # unit has a processing length of 2 m or less. The present invention also provides a microporous thermoplastic resin foam obtained by the above method. A preferred example of the microcellular foam of the present invention has a structure including a thicker surface layer than a general microporous foam, and a core layer having micropores when formed, as in Korean Patent Application 2005-1 1 563 7 The number revealed by the number. The contents of this application are incorporated herein by reference. Therefore, the microcellular foam of the present invention can be used for interior and exterior materials of buildings or optical reflectors for use in display devices. In particular, the microporous hair -17- 200831266 foam is suitable for use in interior and exterior materials of buildings. More particularly, the microcellular foam is suitable for use in interior and exterior materials such as sound insulating materials, insulating materials, building materials, lightweight structural materials, packaging materials, electrical insulating materials, cushioning materials, or seismic materials. Hereinafter, the present invention will be described in more detail with reference to the drawings. Of course, the invention is not limited to the following description. Fig. 3 is a schematic view showing the extrusion and foaming system in which the extrusion and foaming processes are carried out in the preparation of the microcellular foam in accordance with the specific examples of the present invention. Fig. 4 is a cross-sectional view showing an enlarged cross section and a graph for explaining a temperature change occurring in a press die including a press dies of an extrusion and foaming system in a specific example of the present invention. As shown in Figures 3 and 4, in accordance with the method of the present invention, the extrusion process is carried out via an extrusion system wherein the extruder 100, the extrusion die 200, the pultrusion unit 400, and the divider 500 are extruded. The forward directions are arranged in the stated order. In particular, the thermoplastic resin is mixed with a blowing agent using a stirrer 1 1 ,, and the resulting mixture is plasticized during passage through the extruder 1000. The resulting # plasticized material is extruded in a molten state. The extruded product is fed to the extrusion die 200 to give a specific shape. When the extruded product passes through the pressure-reducing zone 205 of the extrusion die 200 of the inner heater 220 via the head 210, the micropores are formed in the extruded product. After curing, the extruded product is discharged from the extrusion die 200, and sequentially passes through a temperature conversion zone 27 and a cooling zone 260 included in the extrusion die 200. The temperature conversion zone 270 has a sudden temperature conversion rate. A cooler 230 is installed inside the cooling zone 260. After passing through the pultrusion unit 400 at a particular pultrusion speed, the extruded product is cut to the desired length using a divider 500. Thus, the desired extruded product is obtained. The pultrusion speed of the pultrusion unit 400 is -18-200831266, which is set according to the desired foam induction ratio. Because the extruded product extruded by the extrusion die 200 is in a cooled and solidified state, and the temperature set at the downstream end of the depressurization zone and the temperature at the upstream end of the cooling zone are such that the temperature difference between the two temperatures is 30 to 200°. C, when the extruded product passes through the temperature conversion zone 270, a foam having a dense surface structure is formed in accordance with the sudden temperature conversion rate. Therefore, even when the extruded product is exposed to atmospheric pressure, it does not expand in the width direction of the extruded product. As a result, the extrusion system can be controlled to have a desired bubble induction ratio in accordance with the pultrusion speed adjustment of the pultrusion unit φ 400 . Therefore, it is possible to finely adjust the foaming ratio of the foam and uniformly control the foaming ratio of the foam, so that the foam has a desired foaming ratio regardless of the elapsed time. It can also prepare a foam having a desired cross-sectional shape regardless of elapsed time. The correction unit 3 00 can be placed between the extrusion die 200 and the pultrusion unit 400 when it is necessary to additionally cool and solidify the extruded product. In this case, the extruded product is extruded by the cooling zone 260 to pass through the correction unit 300. The correction sheet #元3 00 preferably has a processing length of about 2 m or less. This makes it possible to avoid waste of space in the extrusion system and to reduce manufacturing costs. The extrusion speed can be increased due to the reduction in the processing length. As a result, productivity has increased significantly. At the same time, the refrigerant circulator 310 is connected to the cooling zone 260 and/or the correction unit 300 of the extrusion die 200. Therefore, the extruded product is cooled and solidified due to the circulation of the refrigerant. [Embodiment] -19-200831266 Hereinafter, the present invention will be described by way of examples only, but the scope of the present invention is not limited to the embodiments. [Examples 1 to 4] Preparation of an extrusion device for extrusion molding a thermoplastic resin: it is an assembly extrusion die (having an overall structure consisting of a temperature-controllable high-temperature die as a foaming zone), a temperature conversion zone, And the low temperature mold (as the cooling zone of the twin-screw extruder) together with the adapter. In this case, the high temperature mold has a length of 125 mm, the temperature conversion zone has a length of 27 mm, and the low temperature mold has a length of 40 mm. 98 parts by weight of a rigid polyvinyl chloride (PVC) compound (manufactured by LG Chemical Co., Ltd.) was placed in an extruder to completely plasticize the PVC. Thereafter, 2 parts by weight of nitrogen was placed in the barrel of the extruder using a high pressure pump. The single phase mixture was thus molded to produce a PVC sheet having a thickness of 2 mm and a width of 100 mm. Set the conditions of the extruder so that the temperature of the barrel is changed from 190 °C to 180 °C · 1 7 5 °C. At the same time, the adapter is maintained at a temperature of 130 °C. The conditions of the high temperature mode, the temperature transition zone, and the low temperature mode are described in Table 1 below. [Comparative Example 1] A PVC sheet was produced in the same manner as in Example 1, except that a conventional extrusion die was used which included only a high temperature die and did not include an extrusion die (having an integral structure by a temperature controllable high temperature die as a foaming) The zone composition), the temperature conversion zone 'and the low temperature mode (as a cooling zone)' and the cooling process are carried out using a calibration unit having a length of about 4 m -20-200831266. The conditions of the high temperature mold are described in the following Table 10 [Experimental Example 1] The extrusion speeds of the p v C sheet extrusion processes of the above Examples 1 to 4 and Comparative Example 1 were measured. The measurement results are shown in Table 1. <Table 1> Barrel temperature (. Die temperature 挤压 Extrusion product temperature CC) Linear extrusion speed (m/min) Foam induction ratio (%) Cy 1 Cy 2 Cy 3 Cy 4 Ad HT mode LT mode 1 2 1 2 Example 1 190 180 180 180 3.0 130 185 185 30 20 10 3.0 0.0 Example 2 190 180 180 180 3.8 130 185 185 30 20 43 3.8 21.1 Example 3 190 180 180 180 7.0 130 185 185 30 20 51 7.0 57.1 Example 4 190 180 180 180 11.2 130 185 185 30 20 62 11.2 73.2 Comparative Example 1 190 180 180 180 7.0 130 185 185 in] 185 heat 180 7.0 21.1
測量上述實施例1至4和比較實施例1之隨經過時間顯 示之PV C片擠壓製程的發泡率。測量結果述於下列表2。 〈表2> 發泡體誘導 比(％) 實際發泡 率(％) 誤差 (%) 隨經過時間變化之發泡率(％) 下限 上限 實施例1 0.0 0.0 0.0 -0.0 +0.0 實施例2 21.1 21.0 -0.1 -0.3 +0.2 實施例3 57.1 57.4 +0.3 -0.3 +0.5 實施例4 73.2 72.6 -0.8 -0.6 +0.2 比較實 施例1 21.1 26.8 +5.7 -4.8 +5.1 -21 - 200831266 參見表2，可看到實施例1至4的每個PVC片中發泡體 誘導比與實際發泡率之間的誤差相當地低於比較實施例1 所具者。亦可看到具有0.0至73.2%之發泡體誘導比的實施 例1至4的每個PVC片中，隨經過時間變化之發泡率爲相 當地低於具有21.1%之發泡體誘導比的比較實施例1所具者 〇 因此可看到者爲，依據本發明可在廣的發泡率範圍內 穩定地製備具有所需發泡率之經擠壓發泡體。 雖然本發明之較佳具體實例已以說明目的揭示，熟於 此藝者將理解各種不同之修飾、增添和替代均爲可能，但 仍未偏離於隨附申請專利範圍中所揭示之本發明範圍和精 神。 工業適用性 由上文敘述可顯而易知依據本發明方法之擠壓模係配 置成具有預定加工條件而擠壓微孔發泡體，且經擠壓微孔 發泡體在預定發泡體誘導比下藉由拉擠單元拉擠成形。因 此，其可細微地調整該微孔發泡體的發泡率及隨經過時間 顯現之微孔發泡體物理性質，且不管經過時間均可維持所 需的微孔發泡體截面形狀。因爲本發明系統可選擇性地包 括具有短加工長度的校正單元，其可避免擠壓系統的空間 浪費且可降低製造成本。結果，生產力可大幅提高。 【圖式簡單說明】 -22- 200831266 上述者與本發明之其他標的、特徵和其他優點將由下 列結合所附圖式之詳細敘述而更清楚地了解，其φ : 圖1爲說明於微孔發泡體製備中施行一般擠壓和發泡 製程的擠壓和發泡系統示意圖； 圖2爲經由放大的截面和曲線圖來說明僅包括降壓區 之習用擠壓模，且在擠壓模中發生之溫度變化； 圖3爲說明於本發明具體實例中微孔發泡體製備時施 φ 行擠壓和發泡製程的擠壓和發泡系統示意圖；及 圖4爲經由放大的截面和曲線圖來說明本發明包括降 壓區、溫度轉換區、及冷卻區之擠壓模，且在擠壓模中發 生之溫度變化。 【主要元件符號說明】 I 〇 :擠壓機 II :攪拌器 _ 20 :擠壓模 21 :降壓區 22 :外部加熱器 30 :校正單元 3 1 :冷凍劑循環器 40 :拉擠單元 50 :分割器 1〇〇 :擠壓機 11 〇 :攪拌器 -23- 200831266 200 :擠壓模 2 0 5 ·降壓區 210 ：噴頭 220 :內加熱器 230 :冷卻器 2 6 0 :冷卻區 270 :溫度轉換區 3 00 :校正單元 3 1 0 :冷凍劑循環器 4 00 :拉擠單元 5 00 :分割器The foaming ratios of the PV C sheet extrusion processes of the above-described Examples 1 to 4 and Comparative Example 1 as a function of elapsed time were measured. The measurement results are described in Table 2 below. <Table 2> Foam induction ratio (%) Actual foaming rate (%) Error (%) Foaming rate (%) as a function of elapsed time Lower limit upper limit Example 1 0.0 0.0 0.0 -0.0 +0.0 Example 2 21.1 21.0 -0.1 -0.3 +0.2 Example 3 57.1 57.4 +0.3 -0.3 +0.5 Example 4 73.2 72.6 -0.8 -0.6 +0.2 Comparative Example 1 21.1 26.8 +5.7 -4.8 +5.1 -21 - 200831266 See Table 2, The error between the foam induction ratio and the actual expansion ratio in each of the PVC sheets of Examples 1 to 4 was found to be considerably lower than that of Comparative Example 1. It can also be seen that in each of the PVC sheets of Examples 1 to 4 having a foam induction ratio of 0.0 to 73.2%, the foaming ratio as a function of time was considerably lower than the foam induction ratio of 21.1%. In Comparative Example 1, it is thus seen that, according to the present invention, an extruded foam having a desired expansion ratio can be stably produced over a wide range of expansion ratio. While the preferred embodiment of the present invention has been described by way of illustration, it is understood that various modifications, additions and substitutions may be made without departing from the scope of the invention as disclosed in the appended claims. And spirit. Industrial Applicability As apparent from the above, the extrusion die set according to the method of the present invention is configured to have a predetermined processing condition to extrude a microcellular foam, and the extruded microcellular foam is in a predetermined foam. The induction ratio is pultrusion by a pultrusion unit. Therefore, it is possible to finely adjust the foaming rate of the microcellular foam and the physical properties of the microcellular foam which are observed with the elapsed time, and maintain the desired cross-sectional shape of the microcellular foam regardless of the elapsed time. Since the system of the present invention can optionally include a correction unit having a short processing length, it can avoid space waste of the extrusion system and can reduce manufacturing costs. As a result, productivity can be greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS Other features, features, and other advantages of the present invention will become more apparent from the following detailed description of the appended claims. Schematic diagram of an extrusion and foaming system for performing general extrusion and foaming processes in the preparation of a foam; FIG. 2 is a cross-sectional and graph diagram showing a conventional extrusion die including only a pressure-reducing zone, and in an extrusion die The temperature change occurs; FIG. 3 is a schematic view showing an extrusion and foaming system for performing a φ row extrusion and foaming process in the preparation of the microcellular foam in the specific example of the present invention; and FIG. 4 is a cross section and a curve through magnification The figure illustrates the temperature change of the extrusion die of the present invention including the pressure reduction zone, the temperature conversion zone, and the cooling zone, and which occurs in the extrusion die. [Description of main component symbols] I 〇: Extruder II: agitator _ 20: extrusion die 21: pressure reduction zone 22: external heater 30: correction unit 3 1 : refrigerant circulator 40: pultrusion unit 50: Divider 1 挤压: Extruder 11 〇: Stirrer -23- 200831266 200 : Extrusion die 2 0 5 · Depressurization zone 210: Nozzle 220: Inner heater 230: Cooler 2 6 0 : Cooling zone 270: Temperature conversion zone 3 00 : Correction unit 3 1 0 : Refrigerant circulator 4 00 : Pultrusion unit 5 00 : Splitter