**2. Experiments & results**

## **2.1. Fiber preparation**

Flame retardant polyester polymers using phosphorous flame retardant were prepared in a same method as the previous report 2). 3-(Hydroxyphenyl phosphinyl) propanoic acid was used as a phosphorous flame retardant, and was supplied from I company in Korea and used without further purification. The phosphorous content was adjusted 0.65wt% as a phosphorous atom on the basis of flame retardant polyester, and the contents of titanium dioxide were adjusted 0, 0.3, 2.5wt% respectively. Generally, the polyester fibers were called the as bright, semi dull and full dull according to the contents of deluster(titanium dioxide). The brief chemical formula of the flame retardant polyester is shown in Figure 1.2)

Fig. 1. Chemical formula of the flame retardant polyester

The flame retardant polyester polymers were dried in vacuo, the humidity was less than 25ppm based on polymer weight. And as previously reported, the 75d/36f filament yarns were prepared by spin-draw method.

Dyeing were conducted using hose-knitted sample and under the same condition as previously report. Commercially available anthraquinone disperse dyestuff was used for the dyeing test.

Flame retardancies and Dyeing fastnesses were evaluated by FITI Testing & Research Institute in Korea on the standard of LOI(limit oxygen index, KS M ISO 4859-2:2001) and KS K 0903, respectively.

#### **2.2 Flame retardancy with deluster contents**

LOIs according to the titanium content in the flame retardant polyester fiber were shown in Figure 2.

LOI is linearly decreased along with increase of titanium dioxide contents.

Decrease of flame retardancy due to titanium dioxide is not clearly defined, however, it is assumed that by phtocatalytic property of anatase type of titanium dioxide. Titanium dioxide used in this experiment was anatase type produced form Sachtleben Company in Germany under the brand name of Hombitan LWSU. In polyester fiber industry, anastase type titanium dioxide is usually adopted. Another type of titanium dioxide, rutile type, is not adopted in polyester fiber industry. Between both types of titanium dioxides(anatase vs rutile) , anatase type titanium dioxide has a bandgap of 3.2eV 6,7) as shown in Figure 3.

In general, most of the phosphorous compounds, including phosphorous flame retardants in this chapter, are known to lower the photocatalytic activity of titanium dioxide. It is assumed that the flammability is decreased by increase amount of titanium dioxide which has photocatalytic activity8). However, if the good has the LOI value over 30, it is known that it is good flame retardant performance.

Flame retardant polyester polymers using phosphorous flame retardant were prepared in a same method as the previous report 2). 3-(Hydroxyphenyl phosphinyl) propanoic acid was used as a phosphorous flame retardant, and was supplied from I company in Korea and used without further purification. The phosphorous content was adjusted 0.65wt% as a phosphorous atom on the basis of flame retardant polyester, and the contents of titanium dioxide were adjusted 0, 0.3, 2.5wt% respectively. Generally, the polyester fibers were called the as bright, semi dull and full dull according to the contents of deluster(titanium dioxide).

O

The flame retardant polyester polymers were dried in vacuo, the humidity was less than 25ppm based on polymer weight. And as previously reported, the 75d/36f filament yarns

Dyeing were conducted using hose-knitted sample and under the same condition as previously report. Commercially available anthraquinone disperse dyestuff was used for the

Flame retardancies and Dyeing fastnesses were evaluated by FITI Testing & Research Institute in Korea on the standard of LOI(limit oxygen index, KS M ISO 4859-2:2001) and KS

LOIs according to the titanium content in the flame retardant polyester fiber were shown in

Decrease of flame retardancy due to titanium dioxide is not clearly defined, however, it is assumed that by phtocatalytic property of anatase type of titanium dioxide. Titanium dioxide used in this experiment was anatase type produced form Sachtleben Company in Germany under the brand name of Hombitan LWSU. In polyester fiber industry, anastase type titanium dioxide is usually adopted. Another type of titanium dioxide, rutile type, is not adopted in polyester fiber industry. Between both types of titanium dioxides(anatase vs rutile) , anatase type titanium dioxide has a bandgap of 3.2eV 6,7) as

In general, most of the phosphorous compounds, including phosphorous flame retardants in this chapter, are known to lower the photocatalytic activity of titanium dioxide. It is assumed that the flammability is decreased by increase amount of titanium dioxide which has photocatalytic activity8). However, if the good has the LOI value over 30, it is known

LOI is linearly decreased along with increase of titanium dioxide contents.

CH2 CH2 P O

m n

O

CH2 CH2 O

The brief chemical formula of the flame retardant polyester is shown in Figure 1.2)

O CH2 CH2O C

**2. Experiments & results** 

**2.1. Fiber preparation** 

C O

dyeing test.

Figure 2.

K 0903, respectively.

shown in Figure 3.

C O

were prepared by spin-draw method.

**2.2 Flame retardancy with deluster contents** 

that it is good flame retardant performance.

Fig. 1. Chemical formula of the flame retardant polyester

Fig. 2. Flame retardancies with deluster contents

Fig. 3. Bandgaps of various semiconducting metals

Flame Retardancy and Dyeing Fastness of Flame Retardant Polyester Fibers 105

fiber to improve light fastness for using industrial applications such as upholstery and car

To improve the light fastness of the flame retardant polyester fiber, following method was

Manganese acetate is known to be incorporated into the polymer as UV stabilizers under polymerization of flame retardant polyester9). Flame retardant polyester fibers incorporated manganese acetate as the basis of 60, 120, 200, 300 ppm of manganese metal in polymer were polymerized. And the polymers were spun in a same method as above mentioned. The

content(ppm) 60 120 200 300

Light fastness 3~4 3 3 3

Table 3 shows that the light fastness decreases with the content of manganese metal. Above all, the coagulation of the manganese acetate brought about the increase of filtration pressure in the polymerization and spinning process to conducting long period test. If the light fastness is improved, this method would be difficult to apply to commercial

To improve the light fastness of the flame retardant polyester fiber, some UV stabilizers were recommended by UV stabilizer maker. The basic properties of the UV stabilizers used in this test were shown in Table 4. The UV stabilizers were incorporated in polymerization reactor as in the state of ethylene glycol dope and the contents of the UV stabilizers were adjusted to 0.3 wt% based on the polyester polymer. The fibers are prepared as same

Light fastnesses of all flame retardant polyester fibers incorporated various UV stabilizers how negligibly little difference as compared with that not containing the UV

Benzotriazole type UV absorber as dyeing auxiliary was recommended form dyestuff maker and dyeing test was conducted. It is added to dyeing solution whose concentration is owf 1%, and the other conditions are same as the above dyeing method. The light fastnesses are

To investigate the effect of benzotriazol UV absorber on the light fastness of polyester fibers,

increased to the grade over 4(at least 1 grade better that of not treated good).

1. Increase of inorganic UV stabilizer(manganese acetate) in polymer

interior, etc.

**2.5 Light fastnesses improvement** 

results of the light fastness were shown in Table 3.

Table 3. Light fastness with manganese contents.

production of flame retardant polyester fiber.

stabilizers.(same grade of light fastness of 3) 3. Using of UV absorber under dyeing

the UV absorption spectrum is shown in Figure 4.

2. Incorporation of organic UV stabilizer into polymer

chosen and conducted ;

Manganese

method above mentioned.

### **2.3 Dyeing fastnesses with deluster contents**

Table 1 shows dyeing fastness of the flame retardant polyester fibers along with the contents of titanium dioxide used as Deluster.


Table 1. Dyeing fastnesses(grade) with deluster contents.

Among dyeing fastnesses, rubbing and sublimation fastness showed similar trend with Normal PET, but washing fastness was better than Normal PET, light fastness was lower than Normal PET.

It is assumed that washing fastness is related to chain mobility of polyester polymer caused by the difference of glass transition temperature. Flame retardant polyester fiber has lower glass transition temperature than normal PET. Therefore, it has better chain mobility than normal PET, and the uptake of the dyestuff at the same temperature is higher than that of normal PET. 2)

Decrease of light fastness is assumed that the influence of photocatalytic activity of titanium dioxide above mentioned. Under the same condition, light fastness using azo disperse dyestuff has 3~4 grade of level which is somewhat better than that using anthraquinone disperse dyestuff, but the dyeing fastness of the flame retardant polyester fiber shows still inferior property compared to normal PET.

## **2.4 Light fastnesses with phosphorous contents**

We can see the dyeing fastnesses are almost same level of flame retardant polyester and normal polyester except for the light fastness as shown in Table 1.

The effect of phosphorous content in the flame retardant polyester on Light fastness was conducted by varying the phosphorous contents in the polymer(deluster contents are same as 0.3% by weight), and the result is shown in Table 2.


Table 2. Light fastness with phosphorous contents.

Light fastness of Flame retardant polyester fiber is inferior to that of normal PET. The difference is brought about by the content of phosphorous flame retardant, not by the content of titanium dioxide. For that reason, there is a necessity for flame retardant polyester fiber to improve light fastness for using industrial applications such as upholstery and car interior, etc.
