Polyurethane聚氨酯的澆注工藝

1、Chapter 3弟二扁Mixing and Casting Polyurethane攪拌和聚氨酯的澆注This chapter is divided into two parts:Basic mixing and casting Background to mixing and casting 這一篇分為兩部分：攪拌和澆注的基本知 識；攪拌和澆注的背景。The first part covers the steps and equipment required for making a polyurethane part; the second covers more detailed as

2、pects of the process.第一部分涵蓋了制造聚氨酯件的步驟和設備要求，第二 部分涵蓋了聚氨酯工藝的更多的細節(jié)方面的內(nèi)容。3.1Basic Mixing and Casting攪拌和澆注的基本知識There are two basic ways to mix polyurethane:Machine processingManually這里有兩個基本的攪拌聚氨酯的方法：機器攪拌工藝和人工操作。Note: Before any handling of polyurethane chemicals or equipment, all staff and makers must be

3、familiar with the occupational Health and Safety requirements for the use of chemicals and machinery as well as all local rules and regulati ons. Copies of the releva nt Material Safety Data Sheets(MSDSs)must be studied and adhered to. Chapter 14 discusses the subject of health and safety in more de

4、tail.注意：在進行聚氨酯的化學試劑或設備的使用前， 所有的員工及生產(chǎn)商必須對使用這些 化學制品及設備像了解本地政策及習俗一樣的熟悉。相尖的材料的安全成分表的復印件必須拿來學習 并堅持遵守。第14篇就是對健康和安全這一課題的詳細討論。3.1.1Machining Processing機械制造工藝Machine processing should be carried out using the initial setting given by the raw material and the machine manufacturers. Both the machine and the ma

5、chine system must be compatible with each other and capable of allowing fine adjustments.機械的制造工藝應該通過采用聚氨酯原材料商和設備制造商提供的最初設置來進行實施。這些設 備和設備系統(tǒng)必須彼此互相兼容且有很周密的調(diào)整適應功能。The machine must be large eno ugh for the producti on to be completed without a full shutdow n and recharge of the system.這個機器設備必須足夠大，使得產(chǎn)品在生產(chǎn)

6、過程中不能沒有一個完整的斷電再充電系統(tǒng)。Machine casting is ideal for one-shot processes where all the ingredients are mixed in a multi- input machine. Some of the ingredients may be preblended，such as the polyols, catalysts, andextenders.機械澆注對于一次澆注成型的工藝來說是可行的，所有的配料都被混合在一個多端輸入的機器 中。有些配料需要被預混合，像聚氨酯，催化劑以及填充劑。3.1.2Manually

7、 人工操作Basic equipment基礎設方伍Safety gloves, mask, and goggles安全手套，防毒面具以及護目鏡Molds模具-Ovens烤箱Microwave oven 微波爐SCaleS電子稱-Devacuuming system 抽真空系統(tǒng)-Dry nitrogen Supply 下氮氣供應Mixing Container 攪拌鍋Stirring paddleS 攪拌槳-Melting potS for Solid CurativeS(if required)加熱固體激活劑的加熱罐Bonding agents粘結力測試工具Butane burner 丁烷燃燒

8、爐Trimming kniveS修整用的刀具-MaChining equipment(if required)機器設備(如果需要)MeaSuring and teSt equipment(aS required)測量及檢測設備(如果需要)BaSiC Materials 基本 原料PrepolymerS預聚物-Curatives 激活劑-Alternative quaSiprepolymer SyStem可供選擇的預聚化物系統(tǒng)Mold releaSe 脫模劑Pigments顏料Fillers填充劑-PlaStiCiZerS增塑劑(塑料桶?)-Cleaning Solvents干凈的清潔試劑3.1

9、.2.1Method 方法The molding procedure iS a multiStep proCeSS with Several StepS running in parallel.這個注模 過程是一個有多種步驟同時進行的復合工藝。1.Preparation 準備a.Clean and bring molds to temperature清理模具并預熱模具到一定溫度 Make any repairs 修理完畢Clean SurfaCe dirt清理掉表面的灰塵 Remove old mold buildup if neCeSSaryHeat to Curing temperatur

10、e 加熱到固化溫度b.Thaw prepolymers已溶解的聚氨酯Keep in warm parts of Shop在工廠中保持它的溫度Under oven置于烤箱中Polytetramethylene glycol( PTMEG) based Prone to solidify 聚丁二醇傾向于固化 No Center milk in ess中心沒有乳狀渾濁Roll mix to elimi nate temperature VariatiO ns 搖晃攪拌時減少溫度變化c.Melt CUratiVe if necessary加熱激活劑使融化如果需要的話Do nOtoVerheat不要過熱

11、 Only Sufficient for day僅夠1天足量的即可d.Weigh out prepolymer and CUratiVe 稱量預聚物和激活劑Into clean dry Container徹底清理干凈裝的容器MaXimUm depth 25% of height最大深度是總深度的25%Can We USe more than OneContainer for large pours 大的澆注可以使用 1 個以上的 容器e.Bring to COrreCt temperature 調(diào)到合適的溫度Bring to SUPPIier recommended temperature 調(diào)

12、至 U 供應商建議的溫度USe microwave for smaller amou nt可使用微波爐來加熱較小的量f.DegaS 脫氣USe VaCUUm pot使用真空罐APPrOXimately 6KPa(28nHg)VaCUUm 真空壓強在 6Kpa(28HHg) Break VaCUUm if too foamy如果太多的氣泡需要停止抽真空2.MiXing 攪拌a.Add Pigme nt to prepolymer將顏料添加到聚氨酯中Some Pigments need to be PrediSPerSed into the prepolymer 有些顏料需要提前力l至I 聚氨酯中

13、分散幵b.Add CUratiVe to prepolymer in ge ntle Stream 將激活劑緩緩加入到聚氨酯中 Add to mixing Container in a Stream連續(xù)不斷的將激活劑加到攪拌的容器Pour along one edge 沿著一個邊傾倒c.MiX USing ZigZag motion or CrOSS-blending使用曲折的動作曲線來交錯雙向攪拌Do not WhiP in air不要在空氣中攪拌Clea n prepolymer from edges and corners into mix 聚氨酯的邊邊角角都要進行攪 拌Clear mi

14、xes must be Streak free 攪拌器要清理干凈Pigments must be completely dispersed顏料必須完全地在聚氨酯中擴散開d.DegaS again再次脫氣If required degas aga in PrOVided there is SUffiCie nt pot life 倘若在有效的適用期內(nèi) 要 求再次脫氣3.Pouring 澆注a.Add to mold in thin Stream將原料成細股狀澆入模具中Rate of pouri ng must n Ot block in let in mold澆注時不能大股地注入到模具中 In

15、CreaSe height to PreVe nt blockage duri ng pouri ng 在澆注過程中逐漸地增加高度 來防止?jié)沧⑦^程中的中斷b.Polyuretha ne must flow dow n mold and displace air UPWard 聚氨酯必須流入模具flash with knife or by grinding用刀子將飛濺割掉或通過打Clean item清理項中并使得空氣往上排出Mold fill should be from bottom up.模具的澆注需從底部往上面來澆滿All SUrfaCeS must be Wetted With no a

16、dheri ng air bubbles.所有的覆膜面都不能有 氣泡附著在表面。c.Air must not be trapped in mold 空氣絕對不能殘留在模具中 Mold must be titled and/or rotated for undercuts to be completely filledd.Polyurethane should not fold on itself 聚氨酯不能靠自己來混合 Polyurethane that is gelling can fold over on itself and cause fault linese.Pouring must

17、 be completed in time for air bubbles to escape before material gels 澆 注 要及時完成，因為要在材料固化之前使材料中的氣泡跑出Gel point can be determined by drawing a thread from surface, using piece of wire with diameter of a paper clipUse a soft” butane flame to pop surface bubbles用較柔的丁烷火焰將件表面的氣 泡 燃燒掉Always keep flame moving

18、要一直讓火焰不斷移動4.Curing 固化a.Place filled mold in oven 將注滿的模具放入烤箱 Oven set to approximately 10 C higher than initial mix material temperature烤箱 設置到比原料混合攪拌時的溫度高10 CPolyurethane must be not heat up or cool mold聚氨酯不能溫度太高或模具的溫 度太低b.Demold when part have sufficient strength當零件有足夠的強度時可以進行脫模Normally 1 to 2 hours

19、 (See suppliers recommendation)通常是 1 至！J 2 小時(詳見供 應 商的建議)MDI-based systems may be hard but still brittlec.Remove any major flash and sprues除去任何主要的澆注飛濺和澆注口結渣Use sharp knife使用鋒利的刀子Material not as tough as when fully cured 材料不如充分固化后堅硬d.Prepare mold for next pour 為下一次的澆注準備模具 Recoat mold with mold releas

20、e 重 新在模具上j余上月兌模齊This is not always necessary as often more than one casting can be made這個操作 不需要經(jīng)常進行因為不止進行一次澆注Keep hot for next run為下一 輪的澆注保持溫度5.Post curing 后固化a.Return part to oven for 8 to 18 hours for full將件重新放入烤箱進行818小時的 充分固 化Follow supplier recommendations for time and temperature根據(jù)供應商的要求來 設定時間及

21、溫度Cycle is normally overnight 一個循環(huán)一般是一整晚Very hard materials need extra postcure to overcome brittleness 很硬的件需要額夕卜 的后 固化來克服脆性b.Final cleaning of flash lines and sprues 最后的飛濺的清理和澆注熔渣 Remove extrac.Any postmolding machining 脫模后的機加工 Machine dimension to size 機加工到要求尺 寸 Remember thermal expansion 注意受熱膨脹3.

22、2Background to Mixing and Casting攪拌和澆注的基礎3.2.1Introduction 說明The mixing of polyurethane components is to complete chemical reactions that convert the various ingredients to viable products with known properties. There are four main points that must be adhered to:聚氨酯成分的攪拌是完成將化學反應轉化成各種我們需要的性能的產(chǎn)品材料。這里有

23、必須堅持的 四點內(nèi)容：Everything dry and keep dry after use(see 3.2.1.1)在完成使用后所有的東西要保持干燥(詳見3.2.1.1 )Correct weights of all ingredients所有的配料稱量要準確Correct temperatures of ingredients, molds and curing temperatures and times 酉己料溫度，模具溫度以 及固化溫度和時間要正確Correct mixing and casting techniques 正確的攪拌和澆注技巧These are the basic

24、 requirements to produce satisfactory products 這些是工廠生產(chǎn)岀合格產(chǎn)品的基本 要求。3.2.1.1 Dryness of System 系統(tǒng)的干燥Raw materials are no rmally supplied with moisture con tent of less than 0.05%. The prese nee of moisture in the system will result in fine bubbles throughout the entire pour. These bubbles are very smal

25、l and evenly dispersed. Included air bubbles are larger and more randomly dispersed.原材料通常 提供時含水量低于0.05%.含水量的多少在整個澆注系統(tǒng)中會導致氣泡的產(chǎn)生。這些通常氣泡比較小 且均勻分布。也不包含比較大而且不均勻分布的氣泡。All containers must be flushed with dry nitrogen gas prior to resealing after use .Normal commercial compressed nitrogen is dry enough with

26、 a dew point of at least -40 C.在使用過后這些的容器要提前 用干氮填平進行再次密封。通常商業(yè)用的壓縮氮氣是足夠干燥的且露點至少在-40 C。Some curatives such as BDO are very hygroscopic and must be han died with care to prevent the absorption of any moisture.有些激活劑像二醇容易吸濕并且必須要很小心地保護防止吸收到任何的 水分。3.2.2Basic Requirements 基本要求3.2.2.1 Molds 模具Molds for casti

27、ng polyurethane parts can be made from a wide range of materials. The most important factor is that they must be impervious to moisture and not contain any moisture. The other main criterion is that they must not be thermoplastic at the processing temperature. Some of the main materials used to make

28、 molds include the following：澆注聚氨酯的模具可以由多種的材料做成。最重 要的表現(xiàn)是它們不受潮濕的影響不會吸收水分。另一個主要的標準是在工藝過程的升溫中不能是熱塑 性的。制作模具的主要原料一般包括以下的幾種：Polyurethane聚氨酯Aluminum 鋁Epoxy (filled and unfilled)環(huán)氧樹脂(填充的或未填充的)Silicones (either encased or backed )硅膠 Steel 鋼Hard thermoplastics硬的熱性塑料Polyester resins 聚酯樹脂PolyUrethanes, silicOne

29、s, and epoxies are Very USefUl for making molds Of ObjeCtS that need to be reproduced.聚氨酯，硅膠和環(huán)氧樹脂對于需要重新制作產(chǎn)品模具的是非常有用的材料。Molds must be cost effective. A mold may be made in a Single PieCe or in any number of Parts With or WithOUt inserts. The following are some main factors to be Considered in making

30、a mold:模具的成 本要非常劃算。一個模具可以是單獨的一件整體或者是由若干數(shù)量的帶金屬或不帶金屬的零件構成。 下面是制作模具應該要考慮到的主要方面：Value of Part bei ng made被制作的件的價值NUmber of Parts to be PrOdUCed要生產(chǎn)的產(chǎn)品的數(shù)量Finish of Part產(chǎn)品的完成數(shù)量ACCUraCy of SiZe of finished Casting完成的鑄件的尺寸的精確度POSitiOnSandnature of any undercuts任何的咬邊的位置和特點SiZe and ShaPe of in SertS金屬件的尺寸和形狀An

31、y holes in molding模具中的任何孔POSitiO ns allowable for pour holes and vents澆注允許的澆注孔或排氣孔的位置Available pot life of polyuretha ne 聚氨酯的有效使用期Polyuretha ne Shrinks any Where betwee n 0% and 2% on CUring depe nding on the grade and the CUre circle. Room temperature CUre Can have zero Shri nkage. The no rmal rang

32、e of Shri nkage is 1%to1.5%.聚氨酯在固化過程中，任何地方的收縮率根據(jù)級別和固化周期的不同在0%到2%之間。在室溫情況下固化收縮率為0.正常的收縮范圍是1 %到1.5%。Shrinkage is three dimensional. The amount in thin SeCtiOnS may not always be noticeable.收縮是立體的。在比較薄的件上收縮并不是很明顯。3.2.2.2DeSign FaCtorS 設計因素The follow ing are some Points that should be take n into acco U

33、nt Whe n desig n a mold:下面是在設計模具時應該考慮在內(nèi)的幾點：Allow a Slight draw on long Parts to allow for removal if POSSible-1/2to 1?？梢栽试S在長點的件上有1/2到1 的斜度從而方便從模具中拔出。Undercuts Cannot be pulled out切入的不易被拉出來Visible areas are best from molded SUrfaCeS從模具面上得到的可視區(qū)是最好的If the Shrinkage of the SyStem is Un Certain, make the

34、 mold on the smaller limits. If Part is too small, material Can no rmally be removed from the mold.如果這個系統(tǒng)的收縮率不確定，要將模具做到小公差。如果零件太小，材料通常是可以從模具中取出的。-Adding material to the mold is expensive.向模具中添加原料是很昂貴的。For molds in two halves pour One half, cure, mold, release, and the n pour the SeC Ond half.Molds W

35、ith an Undercut-make Vertical Casting slit into two Vertical halves With SCalPel or other thin, SharP knife. Make tight-fitting outer mold to keep the two halves together.因為模具要用來澆兩個半片的件，需要先澆注1半，預熱，裝模，脫模然后再澆注另一半。More details are give n in ChaPter 5.在第5部分會給出更多的細節(jié)。3.2.2.3 EqUiPment 設備The SiZe and complexity Of the equipme nt n eeded depe nd On the n ature Of the PrOdUCtS being produced.根據(jù)生產(chǎn)的產(chǎn)品特性來決定需要的設備的規(guī)格及復雜程度。Weighing equipment 稱量設備-EleCtrOniC SCaleS are the most commonly USed 電子稱是最常用的The Weight range to SUit Weigh ing prepolymer for hand PrOCeSS ing is 5 to 30 kg maximum in at least 1 gr