Flame retardant test of polyester fabric
Polyester is widely used in household fabrics such as work clothes, curtains, furniture coverings, carpets and bedding, as well as interior decorative fabrics for aircraft, automobiles and other transportation vehicles. It is a synthetic fiber with large output and rapid development. Polyester has The shortcoming of easy melting and burning poses safety risks to users. Therefore, the fireproof finishing of fabrics is of great significance to the safety of users.
The fire retardant agent TCEP (trichloroethyl phosphate) complies with domestic and foreign requirements for the use of fire retardant agents and is not included in the list of prohibited fire retardant agents.
When polyester burns, free radicals are produced. The activity of these free radicals continuously destroys the bond between carbons, causing a chain decomposition reaction, thereby producing flammable gases. Due to the presence of Cl and P in the fire retardant, free radicals in the combustion gas are constantly captured, interrupting the combustion cycle and blocking the continuation of combustion. At the same time, the presence of fire retardant reduces the melting point of polyester. When exposed to fire, the fibers melt and drip, preventing the flame from contacting the fibers and reducing the combustion effect.
The high-temperature and high-pressure method is a commonly used coloring method for polyester. The fire-proof finishing of polyester fabrics does not require special equipment, has low cost, wide adaptability, and can be bathed in the same bath as the coloring, saving energy. This article attempts to discuss the finishing effect of using TCEP finishing agent and select the best application process.
1 Experiment
1.1 Experimental materials and equipment
Pure polyester corduroy fabric 300g; Y802N oven; Thermo HeλI O Sα finishing meter; Sartorius L 4 2 0 P electronic balance; Rotade r High temperature coloring machine; LLY07A vertical burner; YG701A washing machine; TCEP industry Used (purity 48.24%).
1.2 Test method
(1) Vertical combustion method: According to GB/T５455-1997 “Fabric Product Combustion Performance Test – Vertical Method”.
(2) Cleaning test before combustion: Clean according to GB/T 17595-1998 “Household Cleaning Procedures Before Fabric Burning Tests for Fabrics”, paragraphs 6.1, 6.2, and 6.3, and the cleaning temperature is 50°C. , dry according to GB/T 8629-2001 “Household Cleaning and Drying Procedure for Fabric Product Testing” flat ironing.
(3) Determination of the P content in the fire-proof finished fabric: Use the phosphomolybdic acid colorimetric method to determine the P content, thereby deducing the amount of TCEP.
(4) Breaking strength test: According to GB/T 3923.1-1997 “Tensile Properties of Fabrics” Part 1: Determination of breaking strength and breaking elongation by strip method.
(5) Tear strength test: According to GB/T 3917.1-1997 “Tear Properties of Fabrics” Part 1: Determination of Tear Strength Impact Pendulum Method.
(6) Test of wash and dye fastness: According to GB/T 3921.3-1997 “Dye fastness test of fabrics – Wash and dye fastness”.
1.3 Preparation of finishing agent emulsion
TCEP is solvent-based and must be formulated into a water/oil emulsion, and the finishing agent emulsion requires high stability before it can be used in actual production. Therefore, emulsifiers and protective glue are used to prepare finishing agent emulsions.
Add the emulsifier into TCEP while stirring, then increase the stirring speed to add water, and finally add protective glue to improve the stability of the finishing agent emulsion.
1.4 High temperature and high pressure finishing process
Considering that the usual high-temperature and high-pressure coloring process for polyester is a bath ratio of 1:20 and 135°C insulation for 60 minutes, the fireproof finishing process is the same. Only the TCEP concentration is selected so that it can be carried out in the same bath as the coloring.
2 Result and discussion
2.1 Stability of finishing agent emulsion
2.1.1 Selection of protective glue
Experiments were conducted on the stability of finishing agent emulsions of three common protective glues: polyvinyl alcohol (PVA), sodium carboxymethyl cellulose (CMC), and hydroxyethyl cellulose (HEC) at different dosages of TCEP. By comparison, the results show that: ① As the concentration of PVA protective glue increases, the viscosity of the finishing agent emulsion increases, the delamination rate decreases, and the stability increases. Only when PVA is at a higher concentration (5.5%) can the finishing agent emulsion meet the usage requirements, that is, no stratification for 120 hours. If you continue to increase the PVA concentration, although the finishing agent emulsion is very stable, it will be too viscous and difficult to penetrate into the fabric, resulting in poor finishing effects. ② The finishing agent emulsion using CMC as protective glue will delaminate after being stored for 2 hours, and the stability is too poor. ③HEC protective glue is the same as PVA. As the concentration of protective glue increases, the stability of the finishing agent emulsion increases. At a lower concentration (2.0%), the finishing agent emulsion can be stored for 140 hours without layering, and the emulsion viscosity is medium
(６0ＰPas), can be used directly for post-processing. Therefore, HEC is suitable for use as TCEP protective glue, PVA can only be used at higher concentrations, and CMC is not suitable for use as TCEP protective glue.
2.1.2 Stability test of finishing agent emulsion
Conduct blank experiments on different TCEP dosages and different concentrations of protective glue HEC.� It shows that when the HEC concentration is greater than 1.5%, the storage stability of the finishing agent emulsion and the stability of the high-temperature and high-pressure (liquor ratio 1:20, 135°C insulation for 60 minutes) blank test are both ideal, and can meet the high-temperature and high-pressure process requirements, and The finishing agent emulsion is thin and suitable for finishing fabrics.
2.2 TCEP concentration selection
Since the thick finishing agent emulsion cannot be turned over quickly with the rotation of the dyeing cylinder, which affects the “dyeing” rate and even “dyeing” properties, it is advisable to treat the fabric with a thin emulsion, using 4%, 5%, 6%. Experiments were conducted at 9 concentrations including %, 7%, 8%, 9%, 10%, 11%, and 12%. Post-finishing process: Soak → Insulate at 135℃ for 60min → Clean and dry
TCEP plays a fireproof role through the synergistic effect of Cl and P. The fireproof performance of the fabric depends on the amount of “dyeing” of TCEP on the fabric. Therefore, the higher the P content of the finished fabric, the The higher the value, the greater the “dyeing” amount of TCEP. The value of the fabric damage length indicates the fire resistance of the post-finished fabric when simulating actual burning. The effectiveness of the process can be further verified by testing the fabric damage length.
From the above experimental data results, it can be found that as the TCEP concentration increases, the P content of the fabric shows a low-high-low trend, and correspondingly, the fabric damage length shows a high-low-high trend. The highest value of P content in the fabric is 0.062mg/300mg sample, and the lowest value of the fabric damage length is 11.1cm. Both values appear when the TCEP concentration is 6%, that is, the “TCEP” of the fabric at this concentration. The amount of dyeing is large and the fireproof effect is good. Therefore, the optimal concentration of TCEP is 6%.
2.3 Comparison of dyeing fastness, strength performance and fire retardant performance of fabrics before and after TCEP high temperature and high pressure fire retardant finishing
The samples with a TCEP concentration of 6% and treated according to the above fireproofing finishing process and the samples without fireproofing finishing were tested for wash-dye fastness, breaking strength, tearing strength and burning properties respectively. There is discoloration in the post-finished sample, but it is not significant, and the color difference between the post-finished sample and the unfinished sample is level 4.
It can be seen from the test results that there is no change in the dyeing fastness of the samples after fireproofing, the breaking strength and tearing strength are almost unchanged, and the fireproofing performance is significantly improved.
3 Conclusion
(1) The high temperature and high pressure method is suitable for fire-proof finishing of polyester fabrics. The finishing agent TCEP is effective for the finishing of polyester fabrics and complies with the requirements of GB 17591-1998 “Fire-proof Woven Fabrics” that the damage length is less than 15cm.
(2) When TCEP is finished by high temperature and high pressure method, hydroxyethyl cellulose (HEC) should be used as protective glue.
(3) The fire prevention effect is good when the liquor ratio is 1:20, the insulation temperature is 135℃ for 60min, and the TCEP concentration is 6%.
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