How To Choose Optical Brightener Agent?

Table of content

General guide
Things to know when choosing optical brightener for plastic
Typical optical brighteners for plastics
How to choose optical brightener for PVC?
How to add optical brighteners into plastics ?

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

Detergent optical brightener CBS-X,DMS/AMS,CBS-155

Paper optical brightener PC, BBU/ BBU-L, VBL/VBL-L

Fiber / Textile 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

Plastic optical brightener OB,OBR,OB-1,KSN,KCB,KSB,FP-127,CBS-127,PF

Paint / Ink optical brightener UVT-1,ST,OEF,RT

Things to know when choosing optical brightener for plastic

1.Whitening effect
whitening effect is related with the substrate to be whiten,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 resolved or evenly dispensed into product.

6.Other components in systems, such as pigments, uv absorber,Titanium dioxide pigments (TiO2 ) absorb light in the same UV wavelength range as fluorescent whiteners and thus reduce OBAs whitening effect.Anatase type titanium dioxide pigments absorb approximately 40% of the incident radiation at 380 nm, 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

as chart below, we listed the typical plastic materials usage 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 process	OB
AbS	Dry powder mix before process	Ob
PC ＜300	Dry powder mix before process	Ob	Heat stability; volatility
PC ＞300	Dry powder mix before process	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 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 base coating	Liquid	Cbs-x	/

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 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,plasticizer in PVC had little effect on OBAs,Processing temperature is normally 100 to 200 degree which mean optical brightener heat stability shall meet. We shall pay attention to solubility and immigration which is important to flexible PVC

How to Choose Optical brightener for polyolefin,pu,engineering plastic,fiber,styrenics,elastomer&rubber?

(this part to be updated)

How to add optical brighteners into plastics ?

Optical brighteners are added during thermoplastic molding process, rather than added in liquid form afterwards, 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 added during polymerization process which in monomer from. in this way, stable heat resistance and low volatility is required for OBAs