One, Ultraviolet harm action Ultraviolet ray is the electromagnetic wave that wavelengh is 136 ～ 390nm, have antiseptic effect, and be in with wavelengh the ultraviolet ray of 250 ～ ­280nm especially effective, early wide application at food industry. But the grease that ultraviolet illuminate can make food medium produces oxidation, pigment happening is decomposed, bring about degenerative corruption. 2, the packing material that can absorb ultraviolet radiation Ultraviolet absorbefacient has two kinds big: The organic compound is ultraviolet absorbefacient and inorganic exceed small particle ultraviolet absorbefacient. Former use earlier and extensive, and the result that latter learns a technology to develop for Namike, the history is shorter but have advantage and development outlook. 1. Absorbefacient of organic ultraviolet ray has ¾­ aid, effective, use convenient good point. But its biggest drawback is poisonous, cannot contact food directly, unless use a layer to close,pack, make the wall that pack is the pure colophony layer that does not have absorbefacient, increased cost so however, increased working procedure and difficulty. 2. Inorganic exceeds absorbefacient of small particle ultraviolet ray, bead diameter is called in the grain inside 1-100nm limits about exceed small grain (particle) . After grain of Cheng Chaowei of content qualitative change, the behavior that can appear to differ completely with solid on function, become " new position of material " , have a lot of distinctive report, magnetism, smooth, mechanical with catalytic function. Ferric oxide exceeds small particle to have very good ultraviolet screen property, ju Naiguang sex, chemical stability, hear resistance is very good, what make a person glad more is to do not have noxiousness, and cost is low. Accordingly, have clear advantage quite with absorbefacient of organic ultraviolet ray, it is a kind of ultraviolet ray absorbefacient that has an outlook extremely. Development uses now titanium of ferric oxide, zinc oxide, oxidation waits, but exceed small particle to absorb ability with ferric oxide the strongest, it can absorb 400nm completely to control the ultraviolet ray of wavelengh. 3. The transparent package that can absorb ultraviolet radiation material:(1) SC compound film is remarkable is, although,use SC compound film can keep out ultraviolet ray, but cannot prevent visible light, and the fall that visible light also can cause quality of the food that pack. Accordingly, should consider the integrated effect of keep out ultraviolet ray and visible light, and this can be passed a few colorant and mineral are added in the adhesive of SC compound film (like frosting) will solve. (2) ferric oxide exceeds particle ultraviolet absorbefacient and its are transparent the packing material that can absorb ultraviolet radiation, it is to use ferric oxide to exceed absorbefacient of atomic ultraviolet ray to make transparent ultraviolet ray draw material. It has two kinds of methods: One kind is exceed absorbefacient of atomic ultraviolet ray to make coating besmear Fu form composite material on base material, have the function that absorbs ultraviolet radiation, maintain the transparency of base material. Another method is to be below the condition that does not add the task to divide powder, the ferric oxide that develops Japan exceeds small particle to mix to shape in injection mould model in using polypropylene, push a filter capable person with forming machine of vertical inject moulding next. Via checking a proof, the sheet that ply controls in １ Mm, basically can end the light under wavelengh 40nm, the visible light of 600nm above can penetrate. The affiliation of general Nanotite measures for: Of sheet 1mm ply add 0.05 ％ , if can raise the dispersive level of particle further, add a quantity to be able to decrease accordingly.
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