Ageing of the resinous after solidify and prevent ageing
After solidify of colophony of not saturated polyester, the meeting in be being used for a long time produces ageing phenomenon, color becomes yellow, chap of hair clear as a result, the surface loses luster, intensity drops, other physics function and chemical function also drop subsequently. The factor that affects colophony ageing is very much, and it is alternate action, mechanism is relatively complex, the use condition with goods (wait like temperature, circumstance getting power) direct and relevant. The element of 3 respects such as the degradation action of the oxygen in emphasizing the effect that analyses ultraviolet ray, air below and ozonic action and water, put forward to defend the measure of ageing.
Ultraviolet action
After solidify of colophony of not saturated polyester, meeting ageing falls in long-term insolate. The reason of smooth ageing comes from two respects; On one hand, smooth energy makes resinous covalent bond happens rupture; On the other hand the impure sex of colophony itself, caused suffer destructive breach. The result makes colophony quickens degradation. Through aerosphere the following sun's rays has different wavelengh. The light of different wavelengh has different energy. All sorts of covalent bond in colophony have different key can, the key that exceeds some kind of covalent bond when the energy of certain wavelengh light can when, rupture with respect to what can make. Ultraviolet wavelengh 300 ～ 400nm, if be absorbed adequately by colophony, its energy can amount to Mol of ／ of 299 ～ 399kJ. Of some covalent bond rupture require energy Mol of ／ of 12 ～ 419kJ, its are corresponding wavelengh is 710 ～ 290nm. Visible ultraviolet ray is sufficient can break these covalent bond. This prismatic energy takes energy of whole sun's rays 12% the left and right sides. It endangers the O ― O in colophony first key of O of ― of key of Cl of ― of key of Br of ― of key, C, C, C, because this is contained haloid flame retardant colophony fizzles out changeably. The ester key in colophony also makes the weak point that suffers attack. As to key of C ― C, can interrupt its light energy to occupy 5 ％ only. To C ― H H of ― of key, O bolts,
The chasteness of colophony itself is spent is to be able to bear or endure another of smooth ageing main factor. The colophony with tall purity does not absorb wavelengh to be more than the light of 300nm commonly. Be destroyed not easily consequently. A few impurity are contained in colophony actually, after foreign matter absorbs ultraviolet radiation, oxidize all right namely, form carbonyl. Carbonyl absorbs wavelengh to be the ultraviolet ray of 280 ～ 330nm. In delivering light energy whole element catenary, degradation happens on weak spot. When having ageing effect to colophony at the same time like other factor, smooth degradation can be quickened again. To prevent smooth ageing, can join ultraviolet absorbefacient in colophony commonly, also weigh smooth stabilizing agent. Absorbefacient of this kind of ultraviolet ray can in fat of dissolve Yu Shu, have intense absorption to ultraviolet ray ability, after drawing light energy, made change is structure of fat of other and harmless Yu Shu can (can wait for) like sub radiant energy, vibration. Great majority contains benzene nucleus in the element of ultraviolet absorbefacient, there is a carbonyl between benzene nucleus, there still is hydroxyl on carbonyl ortho-position. Nucleus of this kind of benzene - carbonyl - the intention that the move since the combination of hydroxyl is absorbed and changes light energy. With 2- hydroxyl 2 benzene ketone is exemple, its absorb ultraviolet mechanism to be as follows. The carbon on the oxygen on the carbonyl on the hydrogen on ① hydroxyl and ortho-position or ortho-position is atomic, pass hydrogen be good at and form 5 yuan or 6 yuan of integrated annulus:
What the stabilization of this kind of integrated annulus and hydrogen bolt is strong concern infirmly. After ② absorbs ultraviolet radiation, light energy adds up to chela annulus to open. Open loop needs to waste energy, hydrogenous key is stabler, absorb ability stronger. ③ chela adds up to annulus to be shut afresh, release energy with other form. The smooth stabilizing agent that is used in colophony has a variety of. The requirement is must the ultraviolet radiation that can absorb 290 ～ 410nm strongly; Itself performance is steady, in shape do not decompose below temperature; As good as colophony consistence, disperse equably easily; Wait without harmful color or noxiousness. Commonly used smooth stabilizing agent has 2- hydroxyl benzoic acid of hydroxyl of 2 benzene ketone, 2- armour ester, 2, 2 hydroxyl of 2’- - 4, 2 armour of 4’- oxygen radical 2 benzene ketone, still have benzene and 3 Zun apperception adds up to salicylic acid of ester of content, salicylic benzene, acetyl to wait.
The oxygen in air and ozonic action
Oxygen and ozone can make colophony happening oxidizes degradation, become angry, exterior chap as a result flakes, electric function drops. Below heat and smooth combined action ageing is quickened. Reach in room temperature avoid when light, ageing progress is slow. The compound such as the Cu that joins in polyester, Co, Zn may submit ion impurity form, can quicken oxidation degradation. Freedom radical is had when quickening ageing chain-reacting property, ruinous bigger. To prevent to check resinous oxidizes degradation, basically use two kinds of methods. After ① makes polyester oxidizes, arise cross oxidation radical group to decompose, interrupt the chain reaction of freedom radical. Can use for this a few decompose an agent, basically be to contain sulfur to contain phosphorous compound, be like:
② uses age resistor, make the oxidation chain-reacting that has begun is stopped. This kind of age resistor is phenol mostly kind or amine compound, be like:
Hydrolysis degradation action
After colophony cross-linking solidify, ester bolts ― COOR reachs ― CH2The key such as ― O ― falls in acid and alkaline catalysis, or in hot water, meeting by hydrolysis, make molecular catenary ruptures, function drops. Add mostly in polyester goods fibre glass increases material and all sorts of filling, water divides easy infiltration to above material and resinous interface, make hydrolysis action aggravate. Preventive measure has: Use in goods surface be able to bear or endure the gel coat colophony with admirable ability in swimming is successive coverture; Undertake coupling agent finishing to fibre glass and filling, produce unripe chemical bond what make with colophony, prevent interfacial space.
