Yuav Ua Li Cas Tswj Kev Kub Ntxhov cuam tshuam rau PP Blown Film Properties?

Polypropylene yog ib qho semi-crystalline thermoplastic uas tsis muaj qhov ntom ntom, cov khoom siv kho tshuab zoo, tshuaj lom neeg tsis kam, tiv thaiv tshav kub thiab rwb thaiv tsev zoo. Nws tau siv dav hauv kev lag luam ntim khoom. Nyob rau hauv ntau yam kev siv, tshuab cua tshuab yog ib daim ntawv tseem ceeb uas nws qhov kev ua tau zoo cuam tshuam ncaj qha los ntawm kev tswj qhov kub thiab txias. Qhov cuam tshuam ntawm kev tswj qhov kub thiab txias ntawm cov khoom ntawm polypropylene tshuab zaj duab xis yog kev sib tham hauv daim ntawv no los ntawm plaub yam: extrusion kub, pwm kub, txias txias thiab cov nyhuv synergistic ntawm tshuab molding piv thiab kub.

Extrusion kub yog lub ntsiab parameter hauv polypropylene tshuab zaj duab xis ntau lawm, uas ncaj qha cuam tshuam cov flowability thiab plasticization zoo. PP muaj qhov melting point ntawm 155 thiab 165 degrees Celsius thiab decomposition kub ntawm ntau tshaj 300 degrees Celsius, yog li lub extrusion kub yog feem ntau ntawm 180 thiab 240 degrees Celsius. Qhov ntau yam no yuav tsum tau ua kom haum raws li cov yam ntxwv ntawm cov khoom siv raw (xws li yaj ntws thiab molecular hnyav faib) thiab cov txheej txheem yuav tsum tau ua.
1.1 Tsawg Extrusion Kub (180-200 degree)
qhov extrusion kub yog tsawg dhau lawm, cov flowability ntawm polypropylene yaj yog txo, uas ua rau nto defects xws li "ntses ob lub qhov muag" thiab weld kab. Cov teeb meem no tshwm sim los ntawm kev ua tsis tiav ntawm cov resin, uas ua rau muaj qhov chaw siab crystallinity thiab tsim cov opaque particle lug. Tsis tas li ntawd, qhov kub thiab txias tuaj yeem ua rau cov nyhuv shearing ntawm cov ntsia hlau, uas tuaj yeem ua rau cov saw hlau molecular tawg thiab txo lub zog tensile thiab tawg elongation ntawm cov yeeb yaj kiab.
1.2 High Extrusion Kub (220-240 degree)
Cov kub kub ua rau cov dej ntws zoo dua. Tab sis cov cua kub ntau dhau ua rau qhov tawg ntawm polypropylene. Qhov no ua rau muaj teeb meem xws li gel hais thiab ripples. Kev hloov pauv kub ua rau cov viscosity yaj tsis sib npaug. Qhov no kuj ua rau zaj duab xis lengthwise thickness hloov. Piv txwv li, yog tias qhov kub hloov pauv hauv lub nruas yog ntau tshaj ± 5 degree, qhov kev ua yeeb yaj kiab thickness yuam kev yuav mus dhau 10%. Qhov no mob siab npaum li cas cov yeeb yaj kiab ua haujlwm hauv cov kauj ruam tom ntej.
1.3 Kub sib xws
Qhov kub ntawm tag nrho cov seem ntawm lub extruder yuav tsum sib xws kom tsis txhob overheating hauv zos los yog overcooling. Cov kub hloov pauv yuav ua rau cov yaj viscosity tsis sib xws thiab qhov ntev ntawm cov yeeb yaj kiab hloov pauv. Piv txwv li, yog tias qhov kub hloov pauv hauv lub nruas yog ntau dua ± 5 degree, qhov kev sib txawv ntawm zaj duab xis thickness yuav dhau 10%, cuam tshuam rau kev ua haujlwm tom qab.

Pwm qhov kub thiab txias yog tus yuam sij rau kev tswj thawj cov duab ntawm polypropylene yaj thaum nws tawm ntawm lub nplhaib pwm thiab ua npuas ruaj khov. Feem ntau yog teem ntawm 220 thiab 230 degrees Celsius, pwm kub yuav tsum tau koom tes nrog extrusion kub los xyuas kom meej uniform yaj ntws.
2.1 Tsis tshua muaj kub (<220°C)
Tsis tshua muaj kub txo yaj flowability, ua rau tsis xws luag xws li dej ripples rau saum npoo ntawm npuas. Thaum cov yaj tsis so tag nrho ntawm lub qhov hluav taws xob ntawm cov pwm, cov dej nthwv dej yog tsim, tsim ib ntus yoj. Tsis tas li ntawd, qhov kub tsis tshua muaj qhov ua rau lub brittleness ntawm npuas, ua rau lawv yooj yim rau rupture thaum lub sij hawm traction.
2.2 High Die Temperature (>230 degree)
Thaum cov kub kub txhim kho cov dej ntws tawm, lawv tuaj yeem cuam tshuam cov npuas stability. Pwm kub yog siab dhau lawm, yuav txo tau yaj viscosity, ua npuas nyob rau hauv cov txheej txheem expansion, uas ua rau lub thickness ntawm cov zaj duab xis. Cov kub kub kuj tseem tuaj yeem ua kom cov oxidative degradation ntawm polypropylene, ua rau tsw ntxhiab thiab discoloration.
2.3 Die Gap thiab Temperature Uniformity
Lub nplhaib tuag tshem tawm yuav tsum tswj tsis pub dhau 0.8 hli txog 1.2 hli thiab ntug ntawm qhov tuag yuav tsum sib npaug. Qhov sib txawv tsis sib xws yuav ua rau cov dej ntws sib txawv hauv cov txheej txheem extrusion, uas yuav ua rau cov yeeb yaj kiab thickness sib txawv. Nyob rau tib lub sijhawm, kev ntsuas kub tsis siv neeg thiab tswj qhov system raws li thermocouple yuav tsum tau siv los tswj pwm kub kom raug thiaj li tsis txhob muaj cua sov hauv zos lossis overcooling.

Qhov ntsuas kub txias yog qhov ntsuas tseem ceeb uas txiav txim siab txog crystallinity thiab pob tshab ntawm polypropylene tshuab zaj duab xis. Polypropylene yog ib nrab -crystalline polymer PP's crystallinity ncaj qha cuam tshuam nws lub cev (xws li tensile lub zog thiab tawg elongation) thiab kho qhov muag khoom (xws li pob tshab thiab glossiness).
3.1 Dej txias (15-25 degree)
Water cooling is the circulation of cooling water around bubbles, which can significantly reduce the crystallinity of the film and improve transparency. When the cooling water temperature is controlled between 15 and 22°C, the film can be more than 90% transparent, with a smooth, blemish-free surface. If the water temperature is too high (>30 degree) thiab zaj duab xis tsis txias txaus, crystallization yuav nce thiab pob tshab yuav raug txo kom sai. Piv txwv li, yog tias cov dej kub qis heev (<15°C), the film becomes viscous and exhibits poor opening properties, although transparency is further enhanced.
3.2 Kev txwv ntawm Cua Txias
Cua txias yog siv cov cua rings kom txias npuas. Cov cuab yeej siv tau yooj yim thiab xav tau qhov chaw tsawg dua, tab sis nws yog qhov nyuaj rau kev tswj kom txias ceev. Polypropylene, nrog nws cov crystallinity siab thiab tsis tshua muaj lub zog yaj, nws yooj yim rau cov npuas wobble thiab tsis sib xws thaum siv cua txias, thiab cov yeeb yaj kiab pob tshab feem ntau qis dua dej txias. Yog li ntawd, daim ntawv thov cua txias hauv kev tsim cov polypropylene blower yog tsawg, thiab daim ntawv thov nyob rau hauv zus tau tej cov polypropylene blower yog ntau dua.
3.3 Cov Dej Txias Dej Flow Rate thiab Uniformity
Cov dej txias txias yuav tsum tau sib koom ua ke nrog dej kub. Kev nce tus nqi ntawm 15-25℃tuaj yeem ua kom txias, tab sis ntau dhau tuaj yeem cuam tshuam rau npuas thiab ua rau wrinkles. Cov txiaj ntsig tsis txaus ua rau qhov tsis txaus cua txias thiab txo cov duab pob tshab. Tsis tas li ntawd, cov rings dej txias yuav tsum tau khaws cia kab rov tav kom tsis txhob muaj dej tsis sib xws thiab cov yeeb yaj kiab thickness sib txawv.

Blowout ratio, uas yog, qhov piv ntawm npuas txoj kab uas hla mus pwm txoj kab uas hla, ncaj qha cuam tshuam lub transverse tensile zog thiab thickness uniformity ntawm cov zaj duab xis. Kev tswj qhov kub thiab txias yuav tsum tau ua kom zoo dua hauv kev hais kwv txhiaj nrog qhov sib piv tawg kom ua tiav qhov kev pom zoo ntawm cov khoom siv ntawm cov yeeb yaj kiab.
4.1 Tshuab-Txoj kev ntsuas qhov ntsuas ntawm qhov ntsuas kub qis
Thaum extrusion kub los yog pwm kub qis, PP yaj yog cov kua dej tsawg thiab yuav tsum tau tawg me me (feem ntau tsawg dua 2.0) los tiv thaiv npuas los ntawm tawg. Nyob rau hauv cov xwm txheej no, qis transverse tensile lub zog ntawm zaj duab xis yog qis dua, tab sis siab dua longitudinal tensile lub zog vim muaj kev cuam tshuam ntawm traction.
4.2 Optimization ntawm blasting piv ntawm qhov kub thiab txias
High temperature enhances the fluidity of the melt, expanding the explosion ratio to 2.0-2.5. This greatly improves the film's transverse tensile strength and thickness uniformity film. However, a high bloating ratio (>2.5) tuaj yeem ua npuas rau wobble thiab txawm tawg.
4.3 Dynamic hloov ntawm kub thiab tawg piv
Nyob rau hauv kev xyaum, kub thiab tshuab- nce ratios yuav tsum tau dynamically hloov raws li cov yam ntxwv ntawm raw khoom (xws li yaj ntws tus nqi) thiab cov khoom yuav tsum tau (xws li zaj duab xis thickness thiab tensile zog). Piv txwv li, kev tsim cov yeeb yaj kiab siab -pob tshab yuav xav tau qis extrusion kub (200-220 degree) thiab lub tshuab me me-nce piv (1.8-}2.0), thaum cov yeeb yaj kiab muaj zog yuav tsum tau kub extrusion ntau dua (220-240 degree) thiab siab dua 0-2 degree).

Ntxiv nrog rau cov pob tshab thiab cov khoom siv kho tshuab, kev tswj qhov kub thiab txias plays lub luag haujlwm tseem ceeb hauv cov cua sov shrinkage, tshuaj tiv thaiv thiab kev ruaj ntseg ntawm polypropylene tshuab zaj duab xis.
5.1 Thaum tshav kub kub Shrinkage
Lub tshav kub shrinkage ntawm polypropylene films yog ze ze rau crystallinity. Cov cua txias qis dua, qhov qis dua qhov crystallinity ntawm zaj duab xis thiab siab dua kub shrinkage. Piv txwv li, cov yeeb yaj kiab txias txias ntawm 15℃pom qhov ntev ntawm cov cua sov shrinkage ntawm 1.5% thiab aa transverse tshav kub shrinkage ntawm 1.8%, thaum cov yeeb yaj kiab txias ntawm 25℃qhia qhov cua sov shrinkage tsawg dua 1.0%.
5.2 Chemical Resistance
High extrusion thiab txias txias tuaj yeem txhim kho cov tshuaj tiv thaiv ntawm cov yeeb yaj kiab. Kev kub siab dua txhawb cov saw hlau molecular hauv polypropylene kom ua kom zoo dua thiab siab dua crystallinity, ua rau lawv tsis kam mus rau acids, alkalis thiab ntsev. Piv txwv li, cov yeeb yaj kiab uas tsim los ntawm 220-240℃tuaj yeem poob qis dua 5% ntawm lawv lub zog tensile tom qab 24 teev ntawm kev ntub dej nrog 5% hydrochloric acid tov, thaum cov yeeb yaj kiab tsim tawm ntawm 180-200℃yuav poob ntau dua 10% ntawm lawv lub zog tensile.
5.3 Txheej Txheem Stability
Kev tswj qhov kub thiab txias kuj cuam tshuam rau kev ruaj ntseg ntawm kev ua yeeb yaj kiab. Kev hloov pauv loj hauv extrusion kub lossis tuag kub tuaj yeem ua rau muaj qhov tsis xws luag xws li cov thickness tsis sib xws thiab wrinkles, cuam tshuam cov txheej txheem tom ntej xws li luam ntawv thiab lamination. Yog li ntawd, niaj hnub polypropylene blower feem ntau siv computerized, tsis siv neeg tswj system thiab thermocouple -raws li ntsuas kub ntsuas los xyuas kom meej stability ntawm ntau lawm.
6. Xaus:
Kev tswj qhov kub thiab txias yog ib kauj ruam tseem ceeb hauv kev tsim cov PP tshuab zaj duab xis, uas cuam tshuam ncaj qha rau cov pob tshab, cov khoom siv kho tshuab, thermal shrinkage thiab kev ruaj ntseg ntawm cov yeeb yaj kiab. Los ntawm optimizing extrusion kub, pwm kub, txias txias thiab tshuab molding piv, cov khoom ntawm cov yeeb yaj kiab tuaj yeem raug tswj hwm. Piv txwv li, siab -kev ua tau zoo PP tshuab moulding zaj duab xis nrog pob tshab Ntau dua lossis sib npaug ntawm pob tshab Ntau dua lossis sib npaug ntawm 90% lub zog Ntau dua lossis sib npaug li 45 MPa, thermal shrinkage Tsawg dua lossis sib npaug li 1.5 Tsawg dua lossis sib npaug li 1.5% yog tsim los ntawm kev siv cov pwm extrusion kub ntawm 2002-2 ° C Cov dej txias txias ntawm 15-22 degree, thiab tshuab moulding piv ntawm 2.0-2.5℃C. Nrog rau kev tsim cov ntaub ntawv tshawb fawb thiab kev siv thev naus laus zis, kev tswj kub yuav ua tau ntau dua thiab ntse thiab meej, muab kev txhawb zog rau polypropylene tshuab zaj duab xis kom dav siv hauv ntim khoom noj, ntim tshuaj, ua liaj ua teb zaj duab xis thiab lwm yam.