How To Choose Optical Brightening Agent?
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
- optical brightener for detergent
including optical brightener CBS-X, DMS/AMS, CBS-155
- optical brightener for paper
including Optical brightener PC, BBU/ BBU-L, VBL/VBL-L
- optical brightener for fiber and textile
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
- optical brightener for plastic
including optical brightener OB, OBR, OB-1, KSN, KCB, KSB, FP-127, CBS-127, PF
- optical brightener for paint and ink
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 many 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 the 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.
Typical Optical Brighteners For Plastics, Detergent
As chart below, we listed the typical plastic and detergent applied optical brightener
| Application | OBAs Adding Form | Typical OBAs | Issue to mind |
| R-PVC | Dry powder mix | OB | Solubility Immigration resistance |
| F-PVC | Dissolve or disperse in Plasticizer | OB |
| Transparent PVC | Plasticizer+OBAs Masterbatch OBAs+PVC Masterbatch | |
| PS | Dry powder mix before processing | OB | |
| ABS | Dry powder mix before processing | OB | |
| PC ＜300 | Dry powder mix before processing | OB | Heat stability; volatility |
| PC ＞300 | Dry powder mix before processing | OB-1 | |
| PU Film | Dry powder mix before process with granules or solution | Single component KCB | Immigration resistance Solubility |
| PU Coating | Dry powder mix before process with a solution | / |
| PU Adhesive | Liquid or dispersion | / |
| PU form | Liquid | Polyhydric alcohol soluble |
| Polyolefin | Dry powder mix | KP 127 KSN | Compatibility PP＞hdpe＞ldpe Immigration resistance |
| PMMA | Dry powder mix | OB KCB | Solubility |
| UPR | Dissolve FWA into UPR Before curing | OB | Solubility No side effect during curing |
| PET | polycondensation | OB-1 | After treatment necessary |
| PA | Spinning | OB-1 | / |
| Detergent Water based coating | Liquid | CBS-X | / |
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
3) How to Choose Optical Brightener for Polyurethane?
4) How to Choose Optical Brightener for Engineering Plastics?
5) How to Choose Optical Brightener for Styrenics?
6) How to Choose Optical Brightener for Rubber
How to Add Whitening Agent Into Plastics?
Optical brighteners are added during the thermoplastic molding process, rather than added in liquid form afterward, that’s the word mass-whitening come from. Generally, OBAs were mixed with powder or granules plastic For flexible PVC, OBAs were added in solution form or dispense into plasticizer. OBAs were used in masterbatch form to gain a better dispense effect in plastic. For PET fiber, some OBAs could add during polymerization process which in monomer form. in this way, stable heat resistance and low volatility is required for OBAs
