Kev Paub Txog Cov Khoom Siv Ntim - Dab tsi Ua Rau Kev Hloov Xim ntawm Cov Khoom Siv Yas?

• Lub oxidative degradation ntawm raw cov ntaub ntawv yuav ua rau discoloration thaum molding ntawm kub;
• Discoloration ntawm colorant ntawm qhov kub thiab txias yuav ua rau discoloration ntawm cov khoom yas;
• Cov tshuaj tiv thaiv ntawm cov xim thiab cov khoom siv raw lossis cov khoom siv ntxiv yuav ua rau cov xim tsis zoo;
• Cov tshuaj tiv thaiv ntawm additives thiab tsis siv neeg oxidation ntawm additives yuav ua rau cov xim hloov;
• Tautomerization ntawm cov xim pigments nyob rau hauv qhov kev txiav txim ntawm lub teeb thiab kub yuav ua rau cov xim hloov ntawm cov khoom;
• Cov pa phem tuaj yeem ua rau muaj kev hloov pauv hauv cov khoom yas.

1. Ua los ntawm Yas Moulding

1) oxidative degradation ntawm raw cov ntaub ntawv yuav ua rau discoloration thaum molding ntawm kub

Thaum lub nplhaib cua sov lossis cov phaj cua sov ntawm cov khoom siv yas molding yog ib txwm nyob rau hauv lub tshav kub vim tsis muaj kev tswj, nws yog ib qho yooj yim ua rau lub zos kub siab heev, uas ua rau cov khoom raw oxidize thiab decompose ntawm kub. Rau cov khoom kub-rhiab heev, xws li PVC, nws yooj yim dua thaum qhov tshwm sim no tshwm sim, thaum nws loj heev, nws yuav kub hnyiab thiab tig daj, lossis txawm dub, nrog rau ntau qhov tsawg molecular volatiles ntws.

Qhov kev degradation no suav nrog cov tshuaj tiv thaiv xws lidepolymerization, random saw scission, tshem tawm cov pab pawg sab nrauv thiab cov khoom hnyav molecular.

• Depolymerization

Cov tshuaj tiv thaiv cleavage tshwm sim ntawm qhov txuas txuas txuas, ua rau cov saw txuas txuas mus rau ib qho los ntawm ib qho, thiab cov monomer generated yog sai volatilized. Lub sijhawm no, qhov hnyav molecular hloov maj mam, ib yam li cov txheej txheem rov qab ntawm cov saw hlau polymerization. Xws li cov thermal depolymerization ntawm methyl methacrylate.

• Random Chain Scission (Degradation)

Kuj tseem hu ua random breaks lossis random break chains. Nyob rau hauv qhov kev txiav txim ntawm txhua yam quab yuam, high-zog hluav taws xob, ultrasonic tsis los yog tshuaj reagents, lub polymer saw tawg tsis muaj ib tug taag point los tsim ib tug tsawg-molecular-yuag polymer. Nws yog ib txoj hauv kev ntawm polymer degradation. Thaum cov saw hlau polymer degrades random, qhov hnyav molecular poob sai, thiab qhov hnyav ntawm cov polymer yog me me heev. Piv txwv li, lub degradation mechanism ntawm polyethylene, polyene thiab polystyrene yog feem ntau random degradation.

Thaum cov polymers xws li PE raug molded ntawm qhov kub thiab txias, txhua txoj hauj lwm ntawm cov saw tseem ceeb yuav tawg, thiab qhov hnyav molecular poob sai heev, tab sis cov txiaj ntsig monomer tsawg heev. Cov tshuaj tiv thaiv no yog hu ua random saw scission, qee zaum hu ua degradation, polyethylene Cov dawb radicals tsim tom qab saws tes muaj zog heev, nyob ib puag ncig los ntawm lwm cov hydrogen ntau dua, nws yooj yim rau kev hloov pauv cov tshuaj, thiab yuav luag tsis muaj monomers tsim.

• Tshem tawm cov khoom hloov

PVC, PVAc, thiab lwm yam tuaj yeem raug tshem tawm cov tshuaj tiv thaiv kev hloov pauv thaum cua sov, yog li lub toj siab feem ntau tshwm rau ntawm qhov ntsuas kub. Thaum polyvinyl chloride, polyvinyl acetate, polyacrylonitrile, polyvinyl fluoride, thiab lwm yam yog rhuab, cov khoom siv yuav raug tshem tawm. Siv polyvinyl chloride (PVC) ua piv txwv, PVC ua tiav ntawm qhov kub hauv qab 180 ~ 200 ° C, tab sis ntawm qhov kub qis (xws li 100 ~ 120 ° C), nws pib dehydrogenate (HCl), thiab poob HCl heev. ceev ceev ntawm ib ncig ntawm 200 ° C. Yog li ntawd, thaum lub sij hawm ua (180-200 ° C), cov polymer nyhav dhau los ua xim tsaus thiab qis zog.

Dawb HCl muaj cov nyhuv catalytic rau dehydrochlorination, thiab hlau chlorides, xws li ferric chloride tsim los ntawm kev ua ntawm hydrogen chloride thiab cov cuab yeej ua, txhawb catalysis.

Ob peb feem pua ​​​​ntawm cov kua qaub absorbents, xws li barium stearate, organotin, lead compounds, thiab lwm yam, yuav tsum tau ntxiv rau PVC thaum lub sij hawm thermal ua kom nws ruaj khov.

Thaum cov kev sib txuas lus cable siv los ua xim rau kev sib txuas lus cable, yog tias cov txheej txheem polyolefin ntawm tooj liab tsis ruaj khov, ntsuab tooj liab carboxylate yuav raug tsim los ntawm polymer-tooj ​​liab interface. Cov tshuaj tiv thaiv no txhawb kev nthuav tawm ntawm tooj liab mus rau hauv cov polymer, ua kom cov catalytic oxidation ntawm tooj liab.

Yog li ntawd, txhawm rau txo qis oxidative degradation tus nqi ntawm polyolefins, phenolic lossis aromatic amine antioxidants (AH) feem ntau ntxiv los txiav tawm cov tshuaj tiv thaiv saum toj no thiab tsim cov dawb radicals tsis muaj zog A·: ROO· + AH-→ ROOH + A·

• Oxidative degradation

Polymer cov khoom raug rau huab cua nqus pa thiab nkag mus rau oxidation los tsim hydroperoxides, ntxiv decompose los tsim active chaw, tsim dawb radicals, thiab ces undergo dawb radical saw tshua (ie, nws pib-oxidation txheej txheem). Polymers raug rau cov pa oxygen hauv huab cua thaum ua thiab siv, thiab thaum tshav kub kub, oxidative degradation yog nrawm.

Lub thermal oxidation ntawm polyolefins belongs rau cov dawb radical saw cov tshuaj tiv thaiv mechanism, uas muaj autocatalytic tus cwj pwm thiab yuav muab faib ua peb kauj ruam: pib, kev loj hlob thiab txiav.

Cov saw scission tshwm sim los ntawm pawg hydroperoxide ua rau txo qis hauv molecular yuag, thiab cov khoom tseem ceeb ntawm kev sib tsoo yog cawv, aldehydes, thiab ketones, uas thaum kawg oxidized rau carboxylic acids. Carboxylic acids ua lub luag haujlwm tseem ceeb hauv catalytic oxidation ntawm hlau. Oxidative degradation yog qhov laj thawj tseem ceeb rau kev puas tsuaj ntawm lub cev thiab cov khoom siv hluav taws xob ntawm cov khoom polymer. Oxidative degradation txawv nrog cov qauv molecular ntawm cov polymer. Lub xub ntiag ntawm oxygen tuaj yeem ua rau muaj kev puas tsuaj ntawm lub teeb, cua sov, hluav taws xob thiab lub zog ntawm cov polymers, ua rau muaj kev cuam tshuam ntau dua. Antioxidants ntxiv rau polymers kom qeeb oxidative degradation.

2) Thaum cov yas ua tiav thiab molded, cov xim decomposes, ploj thiab hloov xim vim nws tsis muaj peev xwm tiv taus qhov kub thiab txias.

Cov pigments lossis dyes siv rau cov xim yas muaj qhov txwv kub. Thaum qhov ntsuas kub no tau mus txog, cov xim lossis cov xim yuav raug hloov pauv tshuaj los tsim ntau yam qis molecular hnyav sib txuas, thiab lawv cov qauv tshuaj tiv thaiv yog qhov nyuaj; cov pigments sib txawv muaj qhov sib txawv. Thiab cov khoom, qhov kub tsis kam ntawm cov xim sib txawv tuaj yeem kuaj tau los ntawm kev tshuaj ntsuam xyuas xws li kev poob phaus.

2. Colorants React with Raw Materials

Cov tshuaj tiv thaiv ntawm cov xim thiab cov khoom siv raw yog feem ntau tshwm sim hauv kev ua cov pigments lossis dyes thiab cov ntaub ntawv raw. Cov tshuaj tiv thaiv no yuav ua rau muaj kev hloov pauv xim thiab degradation ntawm polymers, yog li hloov cov khoom ntawm cov khoom yas.

• Txo cov tshuaj tiv thaiv

Qee cov polymers siab, xws li nylon thiab aminoplasts, yog cov muaj zog acid txo cov neeg ua haujlwm hauv lub xeev molten, uas tuaj yeem txo thiab ploj pigments lossis dyes uas ruaj khov ntawm kev ua haujlwm kub.

• Alkaline Txauv

Alkaline ntiaj teb hlau nyob rau hauv PVC emulsion polymers los yog tej yam stabilized polypropylene tuaj yeem "poob pauv" nrog alkaline ntiaj teb hlau hauv cov xim hloov xim los ntawm xiav-liab rau txiv kab ntxwv.

PVC emulsion polymer yog ib txoj hauv kev uas VC yog polymerized los ntawm nplawm hauv ib qho emulsifier (xws li sodium dodecylsulfonate C12H25SO3Na) aqueous tov. Cov tshuaj tiv thaiv muaj Na +; txhawm rau txhim kho cov cua sov thiab oxygen tsis kam ntawm PP, 1010, DLTDP, thiab lwm yam feem ntau ntxiv. Oxygen, antioxidant 1010 yog cov tshuaj tiv thaiv transesterification catalyzed los ntawm 3,5-di-tert-butyl-4-hydroxypropionate methyl ester thiab sodium pentaerythritol, thiab DLTDP yog npaj los ntawm reacting Na2S aqueous tov nrog acrylonitrile Propionitrile yog hydrolyzed thaum kawg tsim thiodipropionic acid. tau los ntawm esterification nrog lauryl cawv. Cov tshuaj tiv thaiv kuj muaj Na +.

Thaum lub sij hawm molding thiab ua cov khoom yas, cov seem Na + nyob rau hauv cov khoom siv raw yuav hnov ​​​​mob nrog lub pas dej xim uas muaj cov hlau ions xws li CIPigment Red48: 2 (BBC lossis 2BP): XCa2 + 2Na + → XNa2 + + Ca2 +

• Cov tshuaj tiv thaiv ntawm Pigments thiab Hydrogen Halides (HX)

Thaum qhov kub nce mus txog 170 ° C los yog nyob rau hauv qhov kev ua ntawm lub teeb, PVC tshem tawm HCI los ua ib daim ntawv cog lus ob npaug.

Halogen-muaj nplaim-retardant polyolefin los yog xim nplaim-retardant yas khoom kuj yog dehydrohalogenated HX thaum molded ntawm kub.

1) Ultramarine thiab HX cov tshuaj tiv thaiv

Ultramarine xiav xim siv dav hauv cov xim yas lossis tshem tawm lub teeb daj, yog cov tshuaj sulfur.

2) Copper kub hmoov pigment accelerates oxidative decomposition ntawm PVC raw cov ntaub ntawv

Copper pigments tuaj yeem oxidized rau Cu + thiab Cu2 + ntawm qhov kub thiab txias, uas yuav ua rau kom lub decomposition ntawm PVC.

3) Kev puas tsuaj ntawm cov hlau ions ntawm polymers

Qee cov pigments muaj kev puas tsuaj rau cov polymers. Piv txwv li, lub pas dej manganese xim CIPigmentRed48: 4 tsis haum rau molding ntawm PP khoom yas. Yog vim li cas yog tias tus nqi sib txawv ntawm cov hlau manganese ions catalyze hydroperoxide los ntawm kev hloov ntawm electrons hauv thermal oxidation lossis photooxidation ntawm PP. Lub decomposition ntawm PP ua rau kom ceev aging ntawm PP; ester daim ntawv cog lus nyob rau hauv polycarbonate yog ib qho yooj yim rau hydrolyzed thiab decomposed thaum rhuab, thiab thaum muaj hlau ions nyob rau hauv cov xim, nws yog ib qho yooj yim mus txhawb lub decomposition; hlau ions kuj tseem yuav txhawb cov thermo-oxygen decomposition ntawm PVC thiab lwm cov ntaub ntawv raw, thiab ua rau muaj xim hloov.

Txhawm rau ua kom tiav, thaum tsim cov khoom yas, nws yog qhov ua tau thiab ua tau zoo tshaj plaws kom tsis txhob siv cov xim xim uas ua rau cov khoom siv raw.

3. Cov tshuaj tiv thaiv ntawm cov xim thiab cov tshuaj ntxiv

1) Cov tshuaj tiv thaiv ntawm sulfur-muaj pigments thiab additives

Sulfur-muaj pigments, xws li cadmium daj (khoom tov ntawm CdS thiab CdSe), tsis haum rau PVC vim tsis zoo acid kuj, thiab yuav tsum tsis txhob siv nrog lead-muaj additives.

2) Cov tshuaj tiv thaiv ntawm cov khoom siv lead ua nrog cov sulfur-muaj stabilizers

Cov ntsiab lus txhuas hauv chrome daj xim lossis molybdenum liab reacts nrog antioxidants xws li thiodistearate DSTDP.

3) Cov tshuaj tiv thaiv pigment thiab antioxidant

Rau cov khoom siv raw nrog cov tshuaj antioxidants, xws li PP, qee cov pigments kuj yuav hnov ​​​​mob nrog antioxidants, yog li tsis muaj zog ntawm cov antioxidants thiab ua rau thermal oxygen stability ntawm raw cov ntaub ntawv tsis zoo. Piv txwv li, phenolic antioxidants tau yooj yim nqus los ntawm cov pa roj carbon dub los yog ua rau lawv poob lawv cov dej num; phenolic antioxidants thiab titanium ions nyob rau hauv cov khoom yas dawb los yog lub teeb xim tsim phenolic aromatic hydrocarbon complexes ua rau yellowing ntawm cov khoom. Xaiv cov tshuaj tiv thaiv kab mob uas tsim nyog lossis ntxiv cov khoom siv ntxiv, xws li tshuaj tiv thaiv acid zinc ntsev (zinc stearate) lossis P2 hom phosphite los tiv thaiv cov xim dawb (TiO2).

4) Cov tshuaj tiv thaiv ntawm cov xim thiab lub teeb stabilizer

Cov nyhuv ntawm pigments thiab lub teeb stabilizers, tshwj tsis yog rau cov tshuaj tiv thaiv ntawm sulfur-muaj pigments thiab npib tsib xee-muaj lub teeb stabilizers raws li tau piav qhia saum toj no, feem ntau txo cov kev ua tau zoo ntawm lub teeb stabilizers, tshwj xeeb tshaj yog cov nyhuv ntawm hindered amine teeb stabilizers thiab azo daj thiab liab pigments. Cov nyhuv ntawm qhov poob qis yog qhov pom tseeb dua, thiab nws tsis ruaj khov li tsis muaj xim. Tsis muaj lus piav qhia meej rau qhov tshwm sim no.

4. Cov tshuaj tiv thaiv ntawm Additives

Yog tias muaj ntau cov tshuaj ntxiv siv tsis raug, qhov kev xav tsis zoo yuav tshwm sim thiab cov khoom yuav hloov xim. Piv txwv li, nplaim hluav taws kub Sb2O3 reacts nrog sulfur-muaj cov tshuaj tiv thaiv oxidant los tsim Sb2S3: Sb2O3+–S–→Sb2S3+–O–

Yog li ntawd, yuav tsum tau saib xyuas nyob rau hauv kev xaiv ntawm additives thaum txiav txim siab ntau lawm formulations.

5. Kev pab cuam Auto-oxidation ua rau

Qhov tsis siv neeg oxidation ntawm phenolic stabilizers yog ib qho tseem ceeb los txhawb cov xim ntawm cov khoom dawb los yog lub teeb xim. Qhov kev hloov xim no feem ntau hu ua "Pinking" nyob rau txawv teb chaws.

Nws yog ua ke los ntawm cov khoom oxidation xws li BHT antioxidants (2-6-di-tert-butyl-4-methylphenol), thiab zoo li zoo li 3,3′,5,5′-stilbene quinone lub teeb liab cov tshuaj tiv thaiv, Qhov no discoloration tshwm sim. tsuas yog nyob rau hauv lub xub ntiag ntawm oxygen thiab dej thiab nyob rau hauv tsis muaj lub teeb. Thaum raug ultraviolet lub teeb, lub teeb liab stilbene quinone sai sai decomposes rau hauv cov khoom daj ib-ntiv nplhaib.

6. Tautomerization ntawm cov xim xim nyob rau hauv qhov kev ua ntawm lub teeb thiab cua sov

Qee cov xim pigments undergo tautomerization ntawm molecular configuration nyob rau hauv qhov kev txiav txim ntawm lub teeb thiab tshav kub, xws li kev siv CIPig.R2 (BBC) pigments hloov los ntawm azo hom mus rau quinone hom, uas hloov cov thawj conjugation nyhuv thiab ua rau cov tsim ntawm conjugated bonds. . txo qis, ua rau muaj xim hloov ntawm xiav tsaus-glow liab mus rau lub teeb txiv kab ntxwv-liab.

Nyob rau tib lub sijhawm, nyob rau hauv lub catalysis ntawm lub teeb, nws decomposes nrog dej, hloov cov co-crystal dej thiab ua fading.

7. Ua rau cov pa phem

Thaum cov khoom yas khaws cia lossis siv, qee cov khoom siv tsis zoo, txawm tias cov khoom siv raw, cov khoom siv ntxiv, lossis cov xim xim xim, yuav hnov ​​​​mob nrog ya raws hauv huab cua lossis tshuaj lom neeg xws li acids thiab alkalis nyob rau hauv kev ua ntawm lub teeb thiab kub. Ntau yam tshuaj lom neeg ua rau muaj teeb meem tshwm sim, uas yuav ua rau fading lossis discoloration dhau sijhawm.

Qhov xwm txheej no tuaj yeem zam lossis txo qis los ntawm kev ntxiv cov thermal oxygen stabilizers tsim nyog, lub teeb stabilizers, lossis xaiv cov huab cua zoo tiv thaiv additives thiab pigments.