General Guide
Here we could use optical brightener classification as a general guide which we could know if we choosing the right type of optical brightener for our application
including optical brightener CBS-X, DMS/AMS, CBS-155
including Optical brightener PC, BBU/ BBU-L, VBL/VBL-L
including optical brightener 4BK, ER-I/ER-I L, ER-II/ER-II L, EBF/EBF-L, PF / DT, BA, CXT, R4, MST-L, BAC, SWN / AW-L, WGS, NFW
including optical brightener OB, OBR, OB-1, KSN, KCB, KSB, FP-127, CBS-127, PF
including optical brightener UVT-1, ST, OEF, RT
Things to Know When Choosing Brightener Agent For Plastics?
1.Whitening Effect
The whitening effect is related to the substrate to whitening, processing conditions and possible interactions with other components in the formulation.
2.Responsiveness
OBAs should compatible with plastic in case of bleeding. Compared with textile, thermoplastic usage OBAs shall require higher heat resistance and lower volatility.
3.Light Resistance
Fluorescent optical brightener had a limited light resistance, much lower than pigments and most plastics. While in any cases, the photochemical degradation of fluorescent whitening agents shall not yellowing the plastics.
4.Hue
In most cases, people would prefer mid to blue to bluish green shade rather than red.
5.Processing condition
To maximize whitening effect, OBAs should completely resolve or evenly dispensed into product.
6.Other Components
Other components in systems, such as pigments, UV absorber,titanium dioxide pigments (TiO2 ) absorb light in the same UV wavelength range as fluorescent whiteners, thus reduce OBAs whitening effect. Anatase-type titanium dioxide pigments absorb approximately 40% of the incident radiation at 380nm, while rutile type titanium dioxide pigments absorb about 90%. UV absorber absorber the light as well while whitening effectiveness is less reduced.
How to Choose Plastic Whitening Agent?
1) How to Choose Optical Brightener for Polyolefins?
2) How to Choose Optical Brightener for PVC?
It is worth noting that same optical brightener gain different whitening effect in rigid PVC (RPVC) and flexible PVC (FPVC).Bisbenzoxazole or phenyl coumarin group are often used in PVC. When PVC powder, heat stabilizer, fluorescent brightener agent dry mixed, optical brighteners were evenly dispensed. For flexible PVC, OBAs were dissolved or dispersed into plasticizer. It is better to add FWAs in masterbatch form.For transport PVC, optical brightener plus plasticizer masterbatch or OBAs plus PVC masterbatch were used.
Dosage:
normally,50 to 100 mg/kg is enough. To meet the requirement of extreme white with filler in, 500mg/kg optical brightener agent is added.For rutile titanium dioxide PVC system,1000mg/kg OBAs is suggested. in most cases, the plasticizer in PVC had little effect on OBAs, the Processing temperature is normally 100 to 200 degree which means optical brightener heat stability shall meet. We shall pay attention to solubility and immigration which is important to flexible PVC.
In next articles, we will continuously introduce how to choose hydrazine hydrate, AC blowing agent, ferric chloride anhydrous, O-aminophenol, and other important chemicals.
