CN115181435B - Surface modification method of carbon black flame-retardant pigment for in-situ polymerization polyester chip - Google Patents

Abstract

The invention discloses a surface modification method of carbon black flame retardant pigment for in-situ polymerization of polyester chips, and belongs to the technical field of fine chemicals. The surface modification method of carbon black flame retardant pigment for in-situ polymerized polyester chips in the present invention includes the following steps: mix isocyanated carbon black, organic solvent and flame retardant, react in an ice bath under mechanical stirring for 30 to 60 minutes, and then heat to Continue the reaction at 100-120°C for 30-60 minutes; after the reaction is completed, filter, wash and dry the reaction product to obtain the carbon black flame retardant pigment; wherein, the structure of the flame retardant is phosphate ester, phosphonate ester, One or more of the structures of phosphaphenanthrene and phosphine oxide. The carbon black flame retardant pigment of the present invention has a small initial particle size, a small change in particle size after being stored for 30 days, a long storage period, and good storage stability. The polyester fiber prepared by utilizing the carbon black flame retardant pigment of the present invention has a low filter pressure value of less than 0.7MPa, good spinnability, good flame retardant performance, and a limiting oxygen index of more than 28%.

Description

A surface modification method of carbon black flame retardant pigment for in-situ polymerized polyester chips

Technical field

The invention relates to a surface modification method of carbon black flame retardant pigment for in-situ polymerized polyester chips, and belongs to the technical field of fine chemicals.

Background technique

According to the different stages of colorant addition, the dope dyeing method can be subdivided into: polymerization stage dyeing and spinning stage dyeing. Polymerization stage dyeing, also known as in-situ polymerization dyeing, is a method in which colorants are added during the polycondensation stage of synthetic PET macromolecules to prepare colored PET slices, and then the colored PET slices are melt-spun to prepare colored PET fibers. The in-situ polymerization dyeing method is the earliest method for industrialized production of polyester fiber dope dyeing. This method not only has low production cost and can be produced in large quantities, but can also solve the problem of poor compatibility between the pigment particles and the matrix in dope-dyed polyester.

While ensuring excellent taking performance, fibers should also be endowed with functional applications to enhance product competitiveness. At present, all over the world are competing to develop PET flame-retardant products, but existing flame-retardant PET masterbatches often have many problems in practical applications. For example, polyester fibers made of some flame-retardant PET masterbatches will produce polyester fibers when burned. Dense smoke and toxic and harmful gases make it difficult to meet the use requirements; some flame-retardant PET masterbatches have excellent flame retardant properties, but the addition of flame retardants seriously damages the polyester structure and seriously blocks the spinneret, causing the mechanical properties of the fiber to decrease, making it difficult to form Fiber.

Contents of the invention

In order to solve the above problems, the present invention provides a surface modification method of carbon black flame retardant pigment for in-situ polymerized polyester chips, so that the obtained carbon black flame-retardant pigment can be used to prepare in-situ polymerized polyester fiber, which can not only improve the carbon The dispersion properties of black flame retardant pigments in polyester fibers can also impart flame retardant properties and achieve halogen-free flame retardant effects, solving the problems of poor spinnability, high filtration pressure and poor flame retardant effect of traditional flame retardant masterbatch. .

The first object of the present invention is to provide a surface modification method of carbon black flame retardant pigment for in-situ polymerized polyester chips, which includes the following steps:

Mix isocyanated carbon black, organic solvent and flame retardant, react in an ice bath under mechanical stirring for 30 to 60 minutes, then heat to 100 to 120°C to continue the reaction for 30 to 60 minutes; after the reaction is completed, filter, wash and dry the reaction product to obtain The carbon black flame retardant pigment;

Wherein, the structure of the flame retardant is one or more of a phosphate ester, a phosphonate ester, a phosphaphenanthrene, and a phosphine oxide structure.

In one embodiment of the present invention, the flame retardant includes one or more of trihydroxyethyl phosphate, phenylphosphonic acid, and trihydroxymethylphosphine oxide.

In one embodiment of the present invention, the organic solvent is one of toluene, acetone, and butanone.

In one embodiment of the present invention, the mass ratio of the isocyanated carbon black and the flame retardant is 1:2-5.

In one embodiment of the present invention, the usage ratio of the isocyanated carbon black and the organic solvent is 1 to 20 g: 350 mL.

In one embodiment of the present invention, the rotation speed of the mechanical stirring is 200-400 r/min.

In one embodiment of the present invention, the preparation method of the isocyanated carbon black is:

Use a liquid phase oxidant to oxidatively modify the carbon black to obtain oxidized carbon black; then disperse the oxidized carbon black in an organic solvent to obtain an oxidized carbon black dispersion; then add diisocyanate to the oxidized carbon black dispersion and add it in an ice bath The reaction is carried out under the conditions for 30 to 60 minutes, and then the temperature is raised to 80 to 120°C and the reaction is continued for 30 to 60 minutes; after the reaction is completed, the unreacted diisocyanate is removed by rotary evaporation to obtain the isocyanated carbon black;

Wherein, the liquid phase oxidant is one of hydrogen peroxide solution, nitric acid solution, saturated ammonium persulfate solution, perchloric acid, sodium hypochlorite solution, and potassium permanganate solution; the dosage ratio of the carbon black to the liquid phase oxidant It is 1-50g:100mL, more preferably 5-50g:100mL, even more preferably 10-50g:100mL; the oxidative modification is 0.5-10h at 25-100°C, further preferably 50-80°C Oxidative modification takes 3 to 5 hours; the organic solvent is one of toluene, acetone, and butanone; the dosage ratio of oxidized carbon black and organic solvent is 10 to 40 g: 100 mL; the diisocyanate is toluene diisocyanate (TDI ), one of isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), and dicyclohexylmethane diisocyanate (HMDI). More preferably, the diisocyanate is toluene diisocyanate (TDI), isocyanate One of the phorone diisocyanates (IPDI); the mass ratio of diisocyanate and oxidized carbon black is 18-25:50; the rotary evaporation temperature is 75-85°C; the particle size of carbon black is 1-50 μm.

In one embodiment of the present invention, the structure of the flame retardant is as follows:

The second object of the present invention is the carbon black flame retardant pigment prepared by the method of the present invention.

The third object of the present invention is to provide a method for preparing flame-retardant black polyester chips, which includes the following steps:

(1) Mix the carbon black flame retardant pigment, polyester dispersant and polyol of the present invention evenly and grind them to obtain a black flame retardant pigment dispersion;

(2) Add the black flame-retardant pigment dispersion before esterification of the polyester and perform polymerization to obtain the flame-retardant black polyester.

In one embodiment of the present invention, the mass concentration of carbon black flame retardant pigment in the black flame retardant pigment dispersion described in step (1) is 18-25%, and the amount of polyester dispersant is carbon black flame retardant pigment. 15-20% of the mass of burning pigment; the rest is polyol.

In one embodiment of the present invention, the polyol described in step (1) is ethylene glycol.

In one embodiment of the present invention, the polyester dispersant described in step (1) is SUA-300 dispersant (Shiming Technology); the weight average molecular weight is 5000~45000, more preferably 8000~38000, More preferably, it is 10,000-25,000; the number average molecular weight is 1,000-15,000, further preferably 2,500-12,000, and still more preferably 4,000-10,000.

In one embodiment of the present invention, the grinding described in step (1) includes ball mill grinding, sand grinding, ultrafine attritor grinding or two-roller or three-roller grinding.

In one embodiment of the present invention, the step (2) of adding black flame-retardant pigment dispersion before polyester esterification for polymerization is specifically:

Purified terephthalic acid and ethylene glycol are mixed and then reacted in the first and second esterification kettles to obtain polyester esterified oligomers. The catalyst zinc acetate is added in the second esterification kettle, and the dosage is generally about 0.05%. (to DMT weight), then add the black flame retardant pigment dispersion into the polyester esterified oligomer, and then pass through the precondensation kettle and final condensation kettle in sequence, in accordance with the national standard "GB/T 14190-2017 fiber grade polyester" (PET) slice test method" Flame-retardant black polyester slices were made.

The fourth object of the present invention is the flame-retardant black polyester chips prepared by the method of the present invention.

The fifth object of the present invention is to provide a flame-retardant black polyester fiber, which is obtained by melt direct spinning using the flame-retardant polyester chips of the present invention.

The sixth object of the present invention is the application of the carbon black flame retardant pigment, flame retardant black polyester chips, and flame retardant black polyester fiber in functional textiles.

Beneficial effects of the present invention:

(1) By grafting a flame retardant on the surface of carbon black, the present invention can maintain good dispersion of carbon black in in-situ polymerized polyester chips while improving the flame retardant properties of carbon black pigments; in addition, the present invention adopts polyester type The dispersant disperses and grinds the carbon black in the polyol system, reducing the particle size of the carbon black, which is beneficial to its application in the in-situ polymerization of polyester fiber.

(2) When the surface-modified carbon black flame-retardant pigment of the present invention is used to prepare in-situ polymerized polyester chips, it can be more uniformly dispersed in the resin carrier, thereby improving the uniform dispersion of the pigment when preparing raw solution colored fibers. properties and compatibility to avoid pigment particle agglomeration and other phenomena, thus solving the problems of excessive filter pressure value, poor spinnability, uneven distribution of pigment particles in the fiber, etc. in subsequent spinning, and improving the quality of the original liquid dyed fiber. .

(3) The initial particle size of the carbon black flame-retardant pigment prepared by the present invention is small, and the particle size change is small after being stored for 30 days, the storage period is long, and the storage stability is good.

(4) The polyester fiber prepared by using the carbon black flame retardant pigment of the present invention has a low filter pressure value of less than 0.7MPa, good spinnability, good flame retardant performance, and a limiting oxygen index of more than 28%.

Description of drawings

Figure 1 is an SEM image of a polyester fiber prepared from polyester chips with a mass fraction of 2% carbon black flame retardant pigment. (a) is a polyester fiber prepared from polyester chips containing the carbon black flame retardant pigment of Example 1. Ester fiber, (b) is a polyester fiber prepared from polyester chips containing the carbon black flame retardant pigment of Example 2, (c) is a polyester fiber prepared from polyester chips containing the carbon black flame retardant pigment of Example 3. Ester fiber, (d) is a polyester fiber prepared from polyester chips containing the carbon black of Comparative Example 1.

Detailed ways

Preferred embodiments of the present invention are described below. It should be understood that the embodiments are for the purpose of better explaining the present invention and are not intended to limit the present invention.

Test Methods:

Particle size distribution test: Use Nano-ZS90 laser particle size analyzer to measure and test the particle size after being left at room temperature for 30 days.

Filtration performance test: Add 500g PET slices to the flushing equipment to make the melt pressure curve run smoothly, and record the initial pressure P ₀ ; then add 4000g flame-retardant black polyester slices, and then add 500g PET slices after the material is used up, and record the test process The maximum pressure is P _max . It is known that the black pigment content in the flame-retardant black polyester chips is 80g, and the pressure difference ΔP=P _max -P ₀ . The experiment used a 10μm filter. This test is used to evaluate the spinnability of flame retardant black polyester chips.

Observation of fiber surface morphology: The prepared polyester fibers were placed on aluminum foil, sprayed with gold under an accelerating voltage of 30kV, and the surface morphology of the samples was observed with a Zeiss Sigma500 scanning electron microscope. Compared with the unpigmented polyester fiber strands under the same process, √ indicates that the surface morphology is basically similar to the polyester fiber strands, Δ indicates that there are a few particles, and ╳ indicates that there are obvious particles.

Limiting oxygen index test: The oxygen index test is carried out according to the GB/T8924-2005 standard, using the JF-3 oxygen index meter of Nanjing Jionglei Instrument Equipment Co., Ltd. Before starting the measurement, you need to draw a scale line 50mm away from one end of the ignition, then install the other end on the specimen clamp and keep the spline vertical. When measuring, you should first debug and adjust according to the predicted limit oxygen value of the material being measured. Neither the flow rate nor the oxygen concentration should be changed at will during the test.

Theoretical formula of oxygen index: LOI=[O ₂ ]/([O ₂ ]+[N ₂ ])×100%

In the formula: LOI is the limiting oxygen index; [O ₂ ] is the oxygen flow rate (L/min); [N ₂ ] is the nitrogen flow rate (L/min).

Example 1

A surface modification method of carbon black flame retardant pigment for in-situ polymerized polyester chips, including the following steps:

Add 50g of commercially available carbon black (particle size: 15 μm) and 300 mL of hydrogen peroxide solution with a volume concentration of 30% into a 500 mL three-necked flask. Set the temperature to 70°C, react for 4 hours, and then cool, filter, and wash with water. Until the pH value of the leachate is 7; dry the filter cake at 80°C to obtain oxidized carbon black;

Weigh 50g of oxidized carbon black and add it to a three-necked flask containing 300 mL of toluene for dispersion to obtain an oxidized carbon black dispersion; then add 18g of toluene diisocyanate (TDI) to the oxidized carbon black dispersion and react under ice bath conditions for 30 minutes. Then the temperature was raised to 120°C and the reaction continued for 30 minutes; after the reaction was completed, the unreacted toluene diisocyanate was removed by rotary evaporation at 80°C to obtain the isocyanated carbon black;

Add 350 mL toluene, 10 g isocyanated carbon black and 50 g trihydroxyethyl phosphate into a three-necked flask and mix. Stir mechanically at 200 r/min in an ice bath for 30 min, then heat to 120°C and continue the reaction for 60 min; cool, filter, and wash the reaction product. , drying to obtain the carbon black flame retardant pigment.

Example 2

A surface modification method of carbon black flame retardant pigment for in-situ polymerized polyester chips, including the following steps:

Add 50g of commercially available carbon black (particle size: 15 μm) and 100 mL of nitric acid solution with a volume concentration of 68% into a 500 mL three-necked flask, set the temperature to 25°C, react for 2 hours, cool, filter, and wash with water until rinsing The pH value of the effluent is 7; the filter cake is dried at 80°C to obtain oxidized carbon black;

Weigh 50g of oxidized carbon black and add it to a three-necked flask containing 300 mL of acetone for dispersion to obtain an oxidized carbon black dispersion; then add 23g of isophorone diisocyanate (IPDI) to the oxidized carbon black dispersion under ice bath conditions. React for 40 minutes, then raise the temperature to 110°C and continue the reaction for 30 minutes; after the reaction is completed, the unreacted isophorone diisocyanate (IPDI) is removed by rotary evaporation at 80°C to obtain the isocyanated carbon black;

Add 350mL acetone, 10g isocyanated carbon black and 50g phenylphosphonic acid into a three-necked flask and mix, react in an ice bath under mechanical stirring at 200r/min for 30min, then heat to 120°C and continue the reaction for 60min; cool, filter, wash and dry the reaction product Dry to obtain the carbon black flame retardant pigment.

Example 3

A surface modification method of carbon black flame retardant pigment for in-situ polymerized polyester chips, including the following steps:

Add 50g of commercially available carbon black (particle size: 15 μm) and 100 mL of saturated ammonium persulfate solution into a 500 mL three-necked flask in sequence, set the temperature to 60°C, react for 3 hours, cool, filter, and wash with water until the pH of the eluate is reached. The value is 7; dry the filter cake at 80°C to obtain oxidized carbon black;

Weigh 50g of oxidized carbon black and add it to a three-necked flask containing 300 mL of butanone for dispersion to obtain an oxidized carbon black dispersion; then add 25g of diphenylmethane-4,4'-diisocyanate ( 4,4'-MDI) was reacted in an ice bath for 40 minutes, then the temperature was raised to 110°C and the reaction was continued for 30 minutes; after the reaction was completed, unreacted diphenylmethane-4,4'-diisocyanate (4,4'-diisocyanate (4,4'-MDI) was removed by rotary evaporation at 80°C. 4'-MDI) to obtain the isocyanated carbon black;

Add 350 mL of toluene, 10 g of isocyanated carbon black and 50 g of trimethylol phosphine oxide into a three-necked flask and mix. Stir mechanically at 200 r/min in an ice bath for 30 min. Then heat to 120°C and continue the reaction for 60 min. Cool, filter, and wash the reaction product. , drying to obtain the carbon black flame retardant pigment.

Comparative example 1

Commercially available carbon black (particle size: 15 μm) was used directly.

Comparative example 2

The flame retardant trihydroxyethyl phosphate in Example 1 was adjusted to ammonium polyphosphate, and the others were kept the same as in Example 1 to obtain a carbon black flame retardant pigment.

Comparative example 3

Simply physically mix 10g of isocyanated carbon black and 50g of trihydroxyethyl phosphate flame retardant to obtain carbon black flame retardant pigment.

Comparative example 4

Add 350 mL toluene, 10 g commercial carbon black and 50 g trihydroxyethyl phosphate into a three-necked flask and mix, react in an ice bath under mechanical stirring at 200 r/min for 30 min, then heat to 120°C and continue the reaction for 60 min; cool, filter and wash the reaction product , drying to obtain the carbon black flame retardant pigment.

Comparative example 5

The reaction between the isocyanated carbon black and the flame retardant in Example 1 was adjusted to be directly heated to 120°C for 60 minutes, and the other conditions were kept the same as in Example 1 to obtain a carbon black flame retardant pigment.

Comparative example 6

The hydrogen peroxide solution in Example 1 was omitted, and the others were kept the same as in Example 1 to obtain a carbon black flame retardant pigment.

Take 50g of the carbon black flame retardant pigments of Examples 1 to 3 and the carbon black obtained in Comparative Examples 1 to 6, 8g of SUA-300 dispersant (Shiming Technology) and 200g of ethylene glycol and disperse them in a grinding cylinder for 30 minutes, and add 300g Glass beads were ground for 2 h to obtain pigment dispersion.

The obtained dispersion was subjected to a particle size distribution test and a particle size distribution test after being left at room temperature for 30 days. The test results are as follows:

It can be seen from Table 1 that the initial particle size of the carbon black flame retardant pigment after modification in Examples 1 to 3 is small, and the change in particle size is small after being stored for 30 days. However, unmodified carbon black has larger particle size, shorter storage life, and poor storage stability.

Table 1 Particle sizes of carbon black pigment dispersions prepared in Examples 1 to 3 and Comparative Example 1

Example 4

A method for preparing flame-retardant black polyester chips, including the following steps:

(1) Disperse 50g of the carbon black pigment prepared in Examples 1 to 3 and Comparative Examples 1 to 6, 8g of SUA-300 dispersant (Shiming Technology) and 200g of ethylene glycol in a grinding cylinder for 30 minutes, and add 300g of glass. Bead-milled for 2 hours to obtain pigment dispersion;

(2) Mix purified terephthalic acid and ethylene glycol and react in the first and second esterification kettles to obtain polyester esterified oligomers. The catalyst zinc acetate is added in the second esterification kettle in an average amount. At 0.05% (relative to the weight of DMT (dimethyl terephthalate)), the black flame-retardant pigment dispersion is then added into the polyester esterified oligomer, and then passes through the precondensation kettle and final condensation kettle in sequence, Colored slices were made in accordance with the national standard "GB/T 14190-2017 Test Method for Fiber Grade Polyester (PET) Slices" to obtain the flame-retardant black polyester slices; wherein the carbon black flame-retardant pigment was added to the flame-retardant black polyester slices The mass percentage in is 2%.

A single-screw extruder was used to directly melt flame-retardant black polyester chips to prepare polyester fibers with specifications of 150D/36F.

The obtained slices and polyester fiber were tested for performance. The test results are as follows:

Table 2 test results

example Slice filter pressure value (MPa) Fiber surface morphology Limiting oxygen index of fiber (%) Example 1 0.63 √ 30.5 Example 2 0.58 √ 31.3 Example 3 0.7 Δ 28 Comparative example 1 6.3 ╳ twenty two Comparative example 2 4.5 ╳ 26.6 Comparative example 3 4.2 ╳ 26.2 Comparative example 4 5.8 ╳ 25.3 Comparative example 5 2.6 ╳ 27.3 Comparative example 6 5.4 ╳ 25.6

It can be seen from Table 2 that: the surface-modified carbon black flame-retardant pigment dispersions prepared in Examples 1 to 3 have excellent storage stability and small particle size; the prepared in-situ polymerized polyester chips have low filter press value and spinnability. Good, the polyester fiber produced has a high limiting oxygen index and good flame retardant properties. In Comparative Example 1, commercially available carbon black is used, which has poor flame retardant properties, and the dispersion stability of unmodified carbon black is poor; in Comparative Example 2, ammonium polyphosphate is used as the flame retardant, which has a low degree of reaction with isocyanated carbon black. , the flame retardant was not completely grafted onto the carbon black, resulting in poor flame retardant performance; in Comparative Examples 3 to 4, simple physical mixing failed to completely graft the flame retardant onto the carbon black surface, resulting in poor flame retardant performance ; In Comparative Example 5, it is directly heated to 120°C, causing the toluene in the solution to directly volatilize, the viscosity of the solution increases, and the reaction proceeds slowly; in Comparative Example 6, the carbon black is not oxidized, which reduces the number of reactive groups on the surface of the carbon black. , failed to react completely with isocyanate, reducing the dispersion stability and flame retardant properties of carbon black.

Although the present invention has been disclosed above in terms of preferred embodiments, they are not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, The protection scope of the present invention should be defined by the claims.

Claims (8)

1. The surface modification method of the carbon black flame-retardant pigment for the in-situ polymerization polyester chip is characterized by comprising the following steps of:

performing oxidation modification on carbon black by adopting a liquid-phase oxidant to obtain oxidized carbon black; then dispersing the oxidized carbon black in an organic solvent to obtain an oxidized carbon black dispersion liquid; adding diisocyanate into the oxidized carbon black dispersion liquid, reacting for 30-60 min under the ice bath condition, and then heating to 80-120 ℃ for continuous reaction for 30-60 min; removing unreacted diisocyanate by rotary evaporation after the reaction is completed to obtain isocyanate carbon black;

mixing the isocyanate carbon black, the organic solvent and the flame retardant, carrying out ice bath reaction for 30-60 min under mechanical stirring, heating to 100-120 ℃ and continuing to react for 30-60 min; after the reaction is finished, filtering, washing and drying the reaction product to obtain the carbon black flame-retardant pigment;

wherein the flame retardant is one or more of trihydroxyethyl phosphate, phenylphosphonic acid and trimethylol phosphine oxide;

the mass ratio of the isocyanate carbon black to the flame retardant is 1: 2-5;

the dosage ratio of the isocyanate carbon black to the organic solvent is 1-20 g:350mL.

2. The carbon black flame retardant pigment prepared by the method of claim 1.

3. A method for preparing flame retardant black polyester chips, which is characterized by comprising the following steps:

(1) Uniformly mixing the carbon black flame-retardant pigment, the polyester dispersant and the polyol according to claim 2, and grinding to obtain a black flame-retardant pigment dispersion;

(2) And adding a black flame-retardant pigment dispersion before esterification of the polyester, and polymerizing to obtain the flame-retardant black polyester.

4. The method according to claim 3, wherein the mass concentration of the carbon black flame-retardant pigment in the black flame-retardant pigment dispersion in the step (1) is 18-25%, and the amount of the polyester dispersant is 15-20% of the mass of the carbon black flame-retardant pigment; the balance being polyol.

5. A process according to claim 3, wherein the polyol in step (1) is ethylene glycol.

6. The flame retardant black polyester chip prepared by the method of claim 4 or 5.

7. A flame retardant black polyester fiber, characterized in that the flame retardant polyester chip is obtained by melt direct spinning.

8. Use of the carbon black flame retardant pigment of claim 2, the flame retardant black polyester chip of claim 6, the flame retardant black polyester fiber of claim 7 in functional textiles.