Wuhan Handern Classification, performance and characteristics of light stabilizers

日期:2020/12/8 9:51:17 / 閱讀: / 來源:本站

Wuhan Handern Classification, performance and characteristics of light stabilizers

There are many kinds of light stabilizers. According to their mechanism of action, they can be roughly divided into light shielding agents, ultraviolet absorbers, quenchers and free radical traps. Among them, ultraviolet absorption is the most important. www.dressup9x.com Breathable-film-extrusion-machine

1. Light shielding agent
Generally refers to the substance that can reflect and collect the outer line of the element. The addition of light shielding agent enables the plastic to shield ultraviolet light waves and reduce the transmission of external rays, so that the inside is not harmed by ultraviolet light. Carbon black, zinc oxide, some inorganic pigments (such as cadmium yellow, cadmium red, titanium dioxide) and organic pigments (such as phthalocyanine blue, phthalocyanine, etc.), individual fillers are also often used as light shielding agents. Carbon black, zinc oxide and titanium dioxide are commonly used light shielding agents.

(1) Carbon black is the most effective light-shielding agent and a radical chain terminator. Pay attention to the following points when selecting carbon black: ①The particle size is preferably less than 50μm, and 15~25nm is the best. The small particle size can improve the dispersibility and weather resistance; ②The dispersibility in plastics is fine carbon by groove method Black, acetylene carbon black and channel coarse carbon black are better, and furnace fine carbon black is also possible. ③The addition amount should be within 2%. Too much effect is not obvious, but it reduces cold resistance, impact strength and electrical properties. ④ It has a synergistic effect with sulfur-containing stabilizers, but it should not be used in combination with amine and phenolic antioxidants.
(2) Pigments Highly shading pigments have the function of shielding or absorbing harmful wavelengths. This is because the surface of the polymer containing the pigments can reflect most of the energy while absorbing residual energy. For example, cadmium-based pigments, iron red, phthalocyanine blue, and phthalocyanine green added to polyethylene have the above-mentioned functions, that is, it can inhibit ultraviolet light aging. When using pigments, consider the interaction with other additives.  www.dressup9x.com Breathable-film-extrusion-machine
(3) Zinc oxide is a cheap, durable, non-toxic light stabilizer with a particle size of 0.11μm, which has the best effect, and is especially suitable for polyolefins. But because zinc oxide is also a photoactivator, it must be used in combination with peroxide decomposers such as zinc diethyldithioamino acid formate, tris(methylphenyl) phosphite, and dilaurate thiodipropionate. Play excellent synergy.

2. Ultraviolet absorber
A substance that can selectively absorb high-energy ultraviolet light, convert energy, and release or consume energy in the form of heat or harmless low-energy radiation. The commonly used ultraviolet absorbers in industry are: salicylate, benzophenone, benzotriazole, triazine, substituted acrylonitrile, reactive absorber, etc.  www.dressup9x.com Breathable-film-extrusion-machine
There is also a reactive ultraviolet absorber. Generally, reactive groups are attached to benzophenone, benzotriazole or triazine ultraviolet absorber molecules, so that they can be copolymerized with monomers or grafted with polymers, so that they will not volatilize and migrate. The solvent is pumped out. The reactive group is generally acrylic, such as 2-2-yl-4-(methacryl) benzotrivet.


3. Quencher

If the quencher is an organic complex of nickel, it can quickly and effectively "quench" the excited molecules and return them to the ground state, thereby protecting the plastic from UV damage. Several commonly used quenchers are now introduced.

(1) Thiobisphenol type 2,2'-thiobis(4-tert-octylphenol) nickel (AM-101), green powder, relative density 1.06, synergistic effect with UV absorber, used for PE , PP and other fibers, the dosage is 0.1-0.5%.
2,2'-thiobis(4-tert-octylphenol) nickel-n-butylamine complex (UV-1084), light green powder, relative density 1.367 (25℃), melting point 258~281℃, low toxicity , Light color, can improve dyeability. For PE, PP, the dosage is 0.25~0.5%.

(2) Phosphonic acid monoester nickel type such as bis(3.5-di-tert-butyl-4 hydroxybenzyl monoethyl phosphate) nickel (Irgastab2002), light yellow to green powder, melting point 180-200℃, used for PP, PE , PS, PVC, EVA, PA, phenyl ester, the dosage is 0.1~1.0%, synergistic with phenolic antioxidants, UV absorbers, phosphites, etc., has good compatibility and resistance to extraction.
(3) Nickel dithiocarbamate such as N,N-di-n-butyl dithiocarbamate (NBC) flakes, melting point 88℃, and anti-ozone effect, used for PP, PE, fiber, The dosage is 0,25-0.5 parts.

4. Free radical scavenger

The free radical trap is a hindered amine light stabilizer. It does not absorb ultraviolet light, but has the functions of trapping free radicals, singlet energy capture, hydrogen peroxide decomposition, and energy transfer of excited molecules. It is a high-efficiency light stabilizer and is suitable for PO, PUR, PS, ABS, HPS, etc., the common ones are as follows:
(1) Monopiperidine derivatives such as benzoic acid-2,2,6,6-tetramethylpiperidine ester (Tinuvin744), molecular weight 260, melting point 90℃.
    4-(p-toluenesulfonamide)-2,2,6,6-tetramethylpiperidine (GW-310) has better compatibility than PP, ABS, PUR, HDPE, hydrolysis resistance, extraction resistance, and low toxicity , No coloring.
(2) Bispiperidine derivatives such as bis(1,2,2,6,6-pentamethylpiperidine) sebacate (GW-508), used in PO, ABS, PUR, PUC.
(3) Polypiperidine derivatives such as tris(1,2,2,6,6-pentamethylpiperidinyl) nitrite (GW-540), molecular weight 541, melting point 120~122℃, compatibility with PO it is good.

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