Low temperature cationic dyeable polyester composition and preparation method and application thereof

Abstract

The present application discloses a low-temperature cationic dyeable polyester composition and a preparation method thereof. The cationic dyeable polyester composition is mainly composed of aromatic dicarboxylic acid units, aliphatic dibasic acid or its esterified derivatives and ethylene glycol units. The esterified liquid obtained by the reaction of sulfonate compound and ethylene glycol, aliphatic dibasic acid or its esterified derivatives and alkali metal compound are added at any stage before the end of the polymerization reaction, and the esterification reaction rate of the esterified liquid is above 95%. The polyester composition has a low content of insoluble compounds, can be dyed at low temperature, has less foreign matter in the polyester, has good spinnability, less filter pressure increase during spinning, a long filter screen replacement cycle and low cost.

Description

Technical Field

[0001] The present invention relates to a low-temperature cationic dyeable polyester composition and a preparation method and application thereof, and specifically to a cationic dyeable polyester composition capable of low-temperature dyeing, low in insoluble compounds and diethylene glycol content, and low filter pressure rise during spinning. Background Art

[0002] Polyester resin, due to its excellent mechanical properties and chemical characteristics, is widely used in clothing, industrial fibers, magnetic tapes, surface coating films, as well as tire radials, network cables and other industrial fields.

[0003] When used as clothing fiber, in order to improve the dyeability of polyester, isophthalic acid components containing sulfonate groups, represented by sodium isophthalic acid-5-sulfonate, are used as copolymer monomers to prepare copolymer-modified cationic dyeable polyester, or isophthalic acid components containing sulfonate groups are used together with polyethylene glycol for copolymerization modification. However, sulfonate groups are prone to physical cross-linking in polyester, resulting in a significant increase in the melt viscosity of polyester when the inherent viscosity (IV) is not high, resulting in lower yarn strength in the end, limiting its application in some fields with high strength requirements.

[0004] In addition, when the copolyester modified with an isophthalic acid component containing a sulfonate group is melt-spun, the filtration pressure rises rapidly, making it difficult to produce stably.

[0005] In order to improve the viscosity increase phenomenon and filter pressure problem caused by the sulfonate group, Japanese Patent Laid-Open No. 5-25708 discloses a modified polyester fiber, which is modified by using terminal blocking cationic components, polyethers and diol components. The cationic groups in the modified polyester are mainly connected to the ends of the molecular chains, and there are no interacting physical cross-linking groups in the middle of the molecular chains, which greatly reduces the viscosity of the polyester. The strength of the obtained cationic polyester fiber is greatly improved compared with the polyester modified by the isophthalic acid component of the existing sulfonate group. However, the terminal blocking cationic component used in this patent has a carboxylic acid group, and direct addition will cause the problem of high DEG. And the terminal blocking cationic component has the phenomenon of polyester end-capping, which will cause the problem of low molecular weight of the polyester. In addition, due to the introduction of the end-blocking cationic compound of the sheet, the molecular structure of the polymer is close to that of ordinary polyester, and the compactness of the intermolecular structure is relatively high, so that the dyeing temperature of the polymer is higher. Summary of the invention

[0006] The object of the present invention is to provide a polyester composition having excellent cationic dyeability and high strength and a preparation method thereof by suppressing the amount of insoluble compounds in the polymer, thereby suppressing the increase in filtration pressure during polyester spinning. In addition, by introducing an aliphatic dibasic acid or its esterified derivative, the molecular weight of the polyester compound and the dyeing effect are increased.

[0007] The technical solution of the present invention:

[0008] A low-temperature cationic dyeable polyester composition is mainly composed of aromatic dicarboxylic acid structural units and ethylene glycol structural units. The polyester composition contains sulfonate groups as shown in formula 1, and the content of the sulfonate groups as shown in formula 1 accounts for 1000-5000ppm of the total amount of the polyester composition in terms of sulfur element, preferably 1000-3500ppm; the content of the compound as shown in formula 2 is equivalent to less than 10.00mol% of the total amount of the sulfonate groups as shown in formula 1 in terms of sulfur element, preferably less than 5.00mol%; the polymer contains aliphatic dibasic acid structural units; the content of diethylene glycol in the polyester composition is 0.8-5.0wt% relative to the total amount of the polyester composition;

[0009] Formula 1,

[0010] Formula 2,

[0011] In Formula 1 and Formula 2, Y is an alkyl group having 2 to 20 carbon atoms, a phenyl group or an alkylbenzene group, and Z and M are Li ions, Na ions or K ions, respectively.

[0012] The number of carbon atoms in the aliphatic dibasic acid structural unit is preferably 4 to 10, accounting for 0.1 to 10.0 wt % of the polyester composition.

[0013] The present invention also discloses a method for preparing the above-mentioned low-temperature cationic dyeable polyester composition, firstly, an aromatic dicarboxylic acid or its esterified derivative is subjected to an esterification or ester exchange reaction with ethylene glycol to obtain an oligomer, and then the obtained oligomer is subjected to a polymerization reaction to obtain a polyester composition. At any stage before the end of the polymerization reaction, an esterified liquid obtained by reacting a sulfonate compound as shown in formula 3 with ethylene glycol, an aliphatic dicarboxylic acid or its esterified derivative, and an alkali metal compound are added, and the esterification reaction rate of the esterified liquid is above 95%.

[0014] Formula 3,

[0015] In Formula 3, Y is an alkyl group having 2 to 20 carbon atoms, a phenyl group or an alkylbenzene group, and Z is a Li ion, a Na ion or a K ion.

[0016] The amount of the esterification liquid added is preferably 1000 to 3500 ppm based on the total amount of the polyester composition, calculated as sulfur in the esterification liquid.

[0017] The number of carbon atoms of the aliphatic dibasic acid is preferably 4 to 10, and the amount of the aliphatic dibasic acid or its esterified derivative added is preferably 0.1 to 10.0 wt % of the total amount of the polyester composition.

[0018] The alkali metal compound is preferably one or more of lithium acetate, potassium hydroxide or sodium hydroxide, and the added amount thereof is preferably 10 to 1000 ppm relative to the total amount of the polyester composition in terms of the alkali metal element.

[0019] The polymer of the present invention can be dyed at low temperature and has excellent cationic dyeability and strength. The content of diethylene glycol and insoluble compounds is small, and the increase of filtration pressure during spinning can be suppressed. DETAILED DESCRIPTION

[0020] In the prior art, cationic dyeability is generally imparted to polyester by copolymerizing a cationic dyeable component containing a sulfonate group, such as isophthalic acid-5-sulfonate, in polyester. However, since the sulfonate group is distributed in the middle of the polyester molecular chain, the sulfonate group is easily physically cross-linked in the polyester, resulting in an increase in the viscosity of the polyester and a decrease in the strength. At the same time, the hydrolysis resistance of the polyester is also deteriorated.

[0021] Adding terminal blocking cationic components to polyester, the cationic groups in the resulting modified polyester are mainly connected to the ends of the molecular chains, and there are no interacting physical cross-linking groups in the middle of the molecular chains, which can improve the melt viscosity of the polyester. However, since the cationic groups are mainly connected to the ends of the molecular weight, the dyeing properties of the modified polyester are affected. At the same time, the addition of terminal blocking cationic components generally leads to poor polyester reactivity, and the molecular weight of the resulting polyester is not large, which has the problem of low strength. By using aliphatic dicarboxylic acids and their esterified derivatives to modify polyester, the dyeing properties of polyester can be improved, and the molecular weight of the modified polyester can be increased, thereby increasing the strength of the polyester fiber and improving the strength retention rate of the polyester fiber before and after dyeing.

[0022] The cationic dyeable component used in the present invention is a sulfonate compound as shown in Formula 3,

[0023] Formula 3,

[0024] In Formula 3, Y is an alkyl group having 2 to 20 carbon atoms, a phenyl group or an alkylbenzene group, and Z is a Li ion, a Na ion or a K ion.

[0025] The sulfonate compound shown in Formula 3 contains only one hydroxyl reactive group. In the polyester, the sulfonate compound is mainly connected to the end of the molecular chain, and there is no interacting physical cross-linking group in the middle of the molecular chain, so it can ensure that the obtained polyester composition has a higher molecular weight and better strength.

[0026] The sulfonate compound as shown in Formula 3 can be specifically exemplified by 2-sodium carboxybenzenesulfonate, 2-potassium carboxybenzenesulfonate, 3-sodium carboxybenzenesulfonate, 3-lithium carboxybenzenesulfonate, 4-sodium carboxybenzenesulfonate, 2-sodium methyl benzoate, 3-sodium methyl benzoate, 4-sodium methyl benzoate, 2-sodium ethyl benzoate, 2-potassium ethylene glycol benzoate, 3-sodium ethyl benzoate, 4-sodium ethylene glycol benzoate, 3-lithium ethylene glycol benzoate, etc., among which 3-sodium carboxybenzenesulfonate is preferred.

[0027] The polyester composition to which the cationic dyeable component such as the sulfonate compound shown in Formula 3 is added contains the sulfonate group shown in Formula 1,

[0028] Formula 1,

[0029] In Formula 1, Y is an alkyl group having 2 to 20 carbon atoms, a phenyl group or an alkylbenzene group, and Z is a Li ion, a Na ion or a K ion.

[0030] The content of the sulfonate groups as shown in Formula 1 in the polyester composition of the present invention is 1000 to 5000 ppm in terms of sulfur element in the polyester composition. When the content of the sulfonate groups as shown in Formula 1 in the polyester composition is less than 1000 ppm, it is difficult for the obtained product to achieve a satisfactory color concentration in the subsequent dyeing process; when the content of the sulfonate groups as shown in Formula 1 in the polyester composition is higher than 5000 ppm, the growth of the polyester molecular chain will be inhibited, and the polymerization system will terminate the polymerization before reaching the target viscosity, and a polyester composition with good physical properties cannot be obtained. Considering the dyeability and the physical properties of the polyester composition, the content of the sulfonate groups as shown in Formula 1 is preferably 1000 to 3500 ppm in terms of sulfur element in the polyester composition.

[0031] In addition, in order to improve the strength of the polyester composition and reduce the dyeing temperature, the present invention adds an aliphatic dibasic acid or its esterified derivative when preparing the polyester composition, so that the obtained polyester composition contains an aliphatic dibasic acid structural unit. The aliphatic dibasic acid structural unit can be a straight-chain aliphatic dibasic acid structural unit or a branched aliphatic dibasic acid structural unit. The carbon number of the aliphatic dibasic acid structural unit is preferably 4 to 10, and can be specifically a succinic acid structural unit, adipic acid structural unit, azelaic acid structural unit, sebacic acid structural unit, 2,2-dimethyl adipic acid structural unit, etc., among which succinic acid, azelaic acid and sebacic acid structural units are more preferred.

[0032] The content of the aliphatic dicarboxylic acid structural unit is preferably 0.1 to 10.0 wt% relative to the weight of the polyester. When the content of the aliphatic dicarboxylic acid structural unit is too low, the purpose of reducing the dyeing temperature cannot be achieved; when the content of the aliphatic dicarboxylic acid structural unit is too high, there are too many aliphatic copolymer components, resulting in a decrease in the heat resistance of the polyester composition and a decrease in strength. The aliphatic dicarboxylic acid structural unit of the present invention more preferably accounts for 0.5 to 8.0 wt% of the polyester composition.

[0033] Although the use of a monocarboxyl sulfonate compound as shown in Formula 3 can improve the strength of the polyester composition, it is also easy to increase the content of diethylene glycol, and the thermal oxidation resistance of the polyester composition deteriorates. In order to suppress the increase of diethylene glycol, the present invention adds an alkaline compound to the polyester composition, and the alkali metal compound can be potassium hydroxide, sodium hydroxide, magnesium hydroxide, lithium hydroxide, magnesium acetate, potassium acetate, lithium acetate, potassium carbonate, calcium carbonate, magnesium carbonate, sodium hexametaphosphate, etc., among which lithium acetate, potassium hydroxide, and sodium hydroxide are preferred. The alkali metal compound can be added alone or in combination.

[0034] If the content of diethylene glycol in the polyester composition of the present invention exceeds 5.0wt%, the heat and oxidation resistance of the polyester composition will deteriorate, and the regularity of the polyester composition will deteriorate, and the irreversible part of the creep of the fiber in the later stage will increase; if the content of diethylene glycol in the polyester composition is lower than 0.8wt%, the structure of the polyester composition will become tight, affecting the combination of the dye and the dyeable position, and further affecting the uniformity and stability of the dyeing.

[0035] Therefore, in order to ensure that the content of diethylene glycol in the polyester composition of the present invention is within an appropriate range, the amount of the alkali metal compound added is preferably 10 to 1000 ppm relative to the total amount of the polyester composition in terms of the alkali metal element. When the amount of the alkali metal compound added is too much, the color tone of the polyester composition will deteriorate; when the amount of the metal alkali compound added is too low, the generation of diethylene glycol cannot be effectively inhibited.

[0036] However, the alkali metal compound reacts with the sulfonate compound shown in Formula 3 to generate a compound shown in Formula 2.

[0037] Formula 2,

[0038] In Formula 2, M and Z are Li ion, Na ion or K ion, respectively, and Y is an alkyl group having 2 to 20 carbon atoms, a phenyl group or an alkylbenzene group.

[0039] The compound shown in Formula 2 is insoluble in the polyester composition and becomes a foreign body in the melt spinning stage, which increases the filter pressure during melt spinning, shortens the filter replacement cycle in the spinning process, and increases the spinning cost. Therefore, in order to achieve good spinnability and reduce the spinning cost of the polyester composition, the present invention adds the sulfonate compound shown in Formula 3 in the form of an esterified liquid with ethylene glycol, and reduces the terminal carboxyl value by increasing the reaction rate, thereby reducing the reaction probability of the alkali metal compound and the sulfonate compound shown in Formula 3, so that the content of the compound shown in Formula 2 in the polyester composition is less than 10.00 mol% in terms of sulfur element relative to the total amount of sulfonate groups shown in Formula 1, preferably less than 5.00 mol%.

[0040] Specifically, the ester formed by the sulfonate compound shown in Formula 3 and ethylene glycol is shown in Formula 4,

[0041] Formula 4,

[0042] In Formula 4, Y is an alkyl group having 2 to 20 carbon atoms, a phenyl group or an alkylbenzene group, and Z is a Li ion, a Na ion or a K ion.

[0043] The amount of the esterification liquid added is 1000-5000ppm relative to the total amount of the polyester composition in terms of sulfur in the esterification liquid. When the amount of the esterification liquid added is less than 1000ppm, it is difficult for the obtained product to achieve a satisfactory color concentration in the subsequent dyeing process; when the amount of the esterification liquid added is more than 5000ppm, it will inhibit the growth of the polyester molecular chain, causing polymerization head phenomenon, and the molecular weight of the obtained polyester composition is small and the physical properties are poor. Considering the dyeability and the physical properties of the polyester composition, the amount of the esterification liquid added is preferably 1000-3500ppm relative to the total amount of the polyester composition in terms of sulfur in the esterification liquid.

[0044] The esterification rate of the esterification liquid is above 95%. If the esterification rate of the esterification liquid is lower than 95%, a large amount of compound as shown in Formula 2 will be generated, the filtration pressure during melt spinning will increase, the filter replacement cycle in the spinning process will be shortened, and the cost will be greatly increased.

[0045] The preparation method of the cationic dyeable polyester composition of the present invention comprises the following steps: firstly, an aromatic dicarboxylic acid or its esterified derivative is reacted with ethylene glycol to obtain an oligomer by esterification or transesterification reaction, and then the obtained oligomer is polymerized to obtain the polyester composition. At any stage before the end of the polymerization, an esterified liquid obtained by the reaction of a sulfonate compound as shown in formula 3 with ethylene glycol, an aliphatic dicarboxylic acid or its esterified derivative, and an alkali metal compound are added, and the esterification reaction rate of the esterified liquid is above 95%.

[0046] Formula 3,

[0047] In Formula 3, Y is an alkyl group having 2 to 20 carbon atoms, a phenyl group or an alkylbenzene group, and Z is a Li ion, a Na ion or a K ion.

[0048] The aliphatic dibasic acid or its esterified derivative increases the flexible chain of the polyester composition, improves the activity of the polyester composition, and makes it easy for the dye molecules to enter the interior of the polyester, thereby improving the dyeability of the polyester composition. At the same time, the aliphatic dibasic acid or its esterified derivative can promote the polymerization reactivity of the modified polyester, increase the molecular weight of the polyester composition, and is beneficial to the yarn orientation in the spinning process, thereby improving the yarn strength and improving the strength retention rate of the yarn before and after dyeing.

[0049] The aliphatic dibasic acid or its esterified derivative described in the present invention refers to an aliphatic dibasic acid or an esterified derivative of the aliphatic dibasic acid. The number of carbon atoms of the aliphatic dibasic acid is preferably 4 to 10, and the number of carbon atoms of the esterified derivative of the aliphatic dibasic acid is not particularly limited. The number of carbon atoms of the esterified derivative can be greater than 10, as long as it is an esterified derivative formed on the basis of an aliphatic dibasic acid having 4 to 10 carbon atoms. For example, when the aliphatic dibasic acid is sebacic acid, its esterified derivative can be dimethyl sebacic acid, diethyl sebacic acid, etc.

[0050] The aliphatic dibasic acid or its esterified derivative described in the present invention may be a straight-chain aliphatic acid or a branched-chain aliphatic acid, and specifically may be succinic acid, adipic acid, azelaic acid, sebacic acid, dimethyl succinate, dimethyl azelate, dimethyl sebacic acid, 2-2-dimethyl adipic acid, etc., and succinic acid, azelaic acid and sebacic acid are more preferred in the present invention.

[0051] The amount of the aliphatic dicarboxylic acid or its esterified derivative added is preferably 0.1 to 10.0 wt %, more preferably 0.5 to 8.0 wt % of the total amount of the polyester composition.

[0052] The aromatic dicarboxylic acid or its esterified derivatives described in the present invention can be terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, dimethyl terephthalate, dimethyl isophthalate, dimethyl naphthalate, dimethyl phthalate, etc., among which terephthalic acid or dimethyl terephthalate is preferred.

[0053] The esterification reaction can be carried out in an esterification reaction tank where oligomers are pre-existing while continuously adding a slurry of ethylene glycol and aromatic dicarboxylic acid in a molar ratio of 1.05 to 1.50; or it can be carried out in an esterification reaction tank where oligomers are pre-existing after all ethylene glycol and aromatic dicarboxylic acid are added before the esterification reaction starts.

[0054] The transesterification reaction can be carried out by adjusting the molar ratio of ethylene glycol to the aromatic dicarboxylic acid esterified derivative to be in the range of 1.50 to 2.50 to control the appropriate transesterification reaction rate.

[0055] The transesterification catalyst may be any known catalyst, such as oxides of metals such as cobalt, magnesium, manganese, titanium, or acetates thereof, which may be used in combination or alone.

[0056] The polymerization catalyst used in the method for preparing the cationic dyeable polyester composition can be various known polymerization catalysts, such as antimony compounds, germanium compounds, titanium compounds, etc. These catalysts can be used in combination or alone.

[0057] As the esterification and polymerization reaction apparatus for producing the cationic dyeable polyester composition of the present invention, various commonly used reaction apparatuses can be used.

[0058] In order to further improve the heat resistance and strength of the cationic dyeable polyester composition of the present invention, in the preparation process of the cationic dyeable polyester composition, it is preferred to carry out solid phase polymerization after the polymerization reaction is completed.

[0059] The conditions for solid phase polymerization are not particularly limited, and any common reaction conditions in the art may be used. Specifically, the polyester product obtained by the polymerization reaction may be subjected to pre-crystallization treatment, and then solid phase polymerization may be performed at a reaction temperature of 200 to 240° C., a reaction pressure of less than 1000 Pa, and a reaction time of less than 100 hours to obtain the final polyester composition.

[0060] The cationic dyeable polyester composition of the present invention has good physical properties, excellent dyeability, and good dyeing stability. By controlling the amount of terminal carboxyl groups of the esterified liquid of the cationic dye dyeable component, the content of insoluble foreign matter in the polyester composition is low, the foreign matter is less during polyester melt spinning, the filter pressure rises less during the spinning process, the filter screen replacement cycle is long, and the cost is low.

[0061] The determination methods and evaluation methods of various indicators of the present invention are as follows:

[0062] (1) Intrinsic viscosity (IV)

[0063] 0.8 g of the polyester composition chips were dissolved in 10 ml of o-chlorophenol solution, and the intrinsic viscosity was measured using an Ubbelohde viscometer at a water bath temperature of 25±0.2°C.

[0064] (2) Sulfur content in insoluble compounds

[0065] 2 g of the sample was weighed and dissolved in 30 ml of hexafluoroisopropanol. The solution was then filtered using a 4 μm filter paper, and the sulfur content on the filter paper was quantitatively analyzed by SEM-EDX.

[0066] (3) Analysis of sulfur content in polyester compositions

[0067] The sulfur content in the polymer was quantitatively analyzed by SEM-EDX elemental analyzer.

[0068] (4) Dyeing stability evaluation

[0069] The polyester composition was spun to obtain a drawn yarn, and then two drawn fibers were paralleled to obtain a sock under a 22-gauge condition. The sock was dyed in a hot water bath at 130°C for 60 minutes with a dye (Blue.TR) 3% owf, acetic acid 0.5 ml / l, sodium acetate 0.2 g / l, and a bath ratio of 1:100. The dyed samples were overlapped to be opaque and then measured with a spectrophotometer (Datacolor 650 manufactured by Datacolor Asia Pacific (HK) Ltd.) under CEI standard light sources D65, 10 o L* is obtained by measuring color under angular conditions.

[0070] (5) Calculation of the reaction rate of esterification liquid (test of carboxyl content)

[0071] Weigh 0.5 g of the sample and dissolve it in 10 ml of o-cresol. Use 0.2 mol / l sodium hydroxide to test the carboxyl content using a potentiometric titration instrument.

[0072] (6) Diethylene glycol test

[0073] Diethylene glycol in isophthalate diethylene glycol sulfonate solution: weigh 0.5 g of sample and add 10 ml of adipic acid, measure by LC, and determine the diethylene glycol content by internal standard method.

[0074] Diethylene glycol in polyester: Weigh 0.5 g of sample, add ethanolamine and heat to dissolve, add 10 ml of adipic acid, measure by LC, and determine the diethylene glycol content by the internal standard method.

[0075] (7) Heat resistance evaluation method (ΔCOOH, eq / t)

[0076] Weigh 8g of slices and put them into a test tube, heat them at 300℃ under nitrogen for 3 hours, and test the carboxyl content of the slices before and after the heating treatment. If the carboxyl content ΔCOOH before and after the heating treatment (COOH before heating treatment - COOH after heating treatment) is large, it means that the heat resistance of the polyester is relatively poor.

[0077] (8) Content of aliphatic dicarboxylic acid structural units in polyester composition

[0078] A certain amount of the polyester composition is taken, and the content of the fatty diacid in the polyester composition is calculated by the characteristic peaks of hydrogen elements (such as hydrogen of the benzene ring and hydrogen of the straight chain) measured by H-NMR.

[0079] (9) Filter pressure difference ΔPa

[0080] The filter pressure test was conducted using a small filterability test machine. Under certain discharge conditions, cationic dyeable polyester was passed through the filter screen, the filter screen aperture was 5μm, the test temperature was the melting point of polyester + 25°C, the discharge volume was 10g / min, and the pressure before the filter screen 30 minutes after the start of feeding was recorded as the initial pressure Pa1, and the final pressure Pa2 was recorded 1 hour after the initial pressure, then the filter pressure rise value for 1 hour was ΔPa=Pa2-Pa1. The smaller the ΔPa, the less foreign matter there is in the polyester, and the more stable the spinning.

[0081] (10) Fiber strength-elongation product

[0082] Strength and elongation are calculated according to JIS L1013:2010 (Testing methods for chemical fibers, medium and long fibers) 8.8.1. Strength and elongation are measured by ORIENTEC Co., RTC-1225A strength and elongation testing machine. Strength-elongation product = strength × (elongation) 0.5 .

[0083] The advantages of the present invention will be described in detail below by referring to the following examples and comparative examples. The present invention is not limited to the following examples.

[0084] Example 1

[0085] After mixing terephthalic acid (PTA) and ethylene glycol (EG) evenly, put them into the reactor and carry out esterification reaction at 240-260°C. After the esterification reaction is completed, the reaction product is transferred to the polycondensation reactor, and then succinic acid is added, and then the esterification liquid with an esterification rate of 99% is added, and then lithium acetate solution is added, and then the catalyst antimony trioxide and the heat stabilizer trimethyl phosphate are added, and the polymerization reaction is carried out at 260°C-290°C. After the polymer reaches the required viscosity, it is discharged and pelletized to obtain the required polyester composition. The intrinsic viscosity IV of the polyester composition is 0.64dl / g, the filter pressure difference of the polyester is 0.20MPa / h, and the diethylene glycol (DEG) content is 2.5wt%.

[0086] The above slices were melt-spun at 290°C to obtain cationic dyeable polyester yarn. The sulfur content in the fiber was 2450ppm, and the sulfur content in the aqueous solution after hot water treatment was 4.7ppm, accounting for 0.19% of the total sulfur content of the polyester composition. The strength-elongation product of the fiber was 24, and the L value after dyeing was 25 when the blue dye concentration was 3.0%owf.

[0087] Example 2

[0088] The cationic dyeable polyester composition was prepared by changing the type of aromatic dicarboxylic acid or its esterified derivative and keeping the other conditions the same as in Example 1. The specific physical properties are shown in Table 1.

[0089] Embodiments 3 to 6

[0090] The amount of sulfonate added as shown in Formula 3 was changed, and other conditions were the same as in Example 1 to prepare a cationic dyeable polyester composition. Specific physical properties are shown in Table 1.

[0091] Example 7

[0092] The reaction rate of the sulfonate esterification liquid shown in Formula 3 is changed, that is, the terminal carboxyl value of the sulfonate esterification liquid is changed, and the other conditions are the same as those in Example 1 to prepare a cationic dyeable polyester composition. Specific physical properties are shown in Table 1.

[0093] Embodiments 8 to 12

[0094] The amount of the alkali metal compound lithium acetate added was changed, and other conditions were the same as in Example 1 to prepare a cationic dyeable polyester composition. Specific physical properties are shown in Tables 1 and 2.

[0095] Embodiments 13-14

[0096] The cationic dyeable polyester composition was prepared by changing the type of alkali metal compound and keeping the other conditions the same as in Example 1. The specific physical properties are shown in Table 2.

[0097] Embodiments 15-16

[0098] The cationic dyeable polyester composition was prepared by changing the type of sulfonate as shown in Formula 3 and keeping the other conditions the same as in Example 1. The specific physical properties are shown in Table 2.

[0099] Embodiment 17

[0100] After the polymerization reaction, solid phase polymerization was carried out under the conditions of reaction temperature of 230° C., reaction pressure of 50 Pa, and reaction time of less than 80 hours. Other conditions were the same as those in Example 1 to prepare a cationic dyeable polyester composition. The specific physical properties are shown in Table 2.

[0101] Examples 18 to 23

[0102] The cationic dyeable polyester composition was prepared by changing the amount of the aliphatic dibasic acid or its esterified derivative, and other conditions were the same as those in Example 1. The specific physical properties are shown in Table 3.

[0103] Embodiments 24 to 25

[0104] The cationic dyeable polyester composition was prepared by changing the type of aliphatic dibasic acid or its esterified derivative and other conditions were the same as in Example 1. The specific physical properties are shown in Table 3.

[0105] Comparative Example 1

[0106] The sulfonate sodium 3-carboxybenzenesulfonate was directly added, and the other conditions were the same as those in Example 1 to prepare a cationic dyeable polyester. The specific physical properties are shown in Table 4.

[0107] In Comparative Example 1, due to the direct addition of unesterified sodium 3-carboxybenzenesulfonate, the amount of insoluble compounds as shown in Formula 2 in the polyester composition is too large, and finally there are more foreign matter in the polyester melt filter pressure test, the filter pressure difference ΔPa is relatively large, and the spinning is more unstable.

[0108] Comparative Example 2

[0109] The unesterified sodium 3-carboxybenzenesulfonate monomer was directly added without adding an alkali metal compound, and the other conditions were the same as those in Example 1 to prepare a cationic dyeable polyester. The specific physical properties are shown in Table 4.

[0110] Since the unesterified sodium 3-carboxybenzenesulfonate monomer is directly added, there are more terminal carboxyl groups and the entire polymer system is acidic. Without the addition of DEG inhibitor alkali metal compounds, excessive diethylene glycol is easily generated. Diethylene glycol will cause the heat resistance of the polymer to deteriorate and easily cause the polymer to have a leading phenomenon, so that the final IV of the polyester is lower.

[0111] Comparative Example 3

[0112] A sulfonate esterification liquid with a reaction rate of 99% was added, but no alkali metal compound was added. Other conditions were the same as those in Example 1 to prepare a cationic dyeable polyester. The specific physical properties are shown in Table 4.

[0113] Although the reaction rate is 99% in the esterification liquid, the free acidic ions are less, but due to the large amount of excess EG, it is still easy to generate too much diethylene glycol without adding alkali metal compounds as DEG inhibitors. Diethylene glycol will cause the heat resistance of the polymer to deteriorate, and the physical properties of the final polyester will be poor.

[0114] Comparative Examples 4 to 6

[0115] The reaction rate of the sulfonate esterification solution was changed, and other conditions were the same as in Example 1 to prepare a cationic dyeable polyester composition. Specific physical properties are shown in Table 4.

[0116] Although sodium 3-carboxybenzenesulfonate is esterified, the reaction rate is low and the amount of terminal carboxyl groups is large, resulting in too much insoluble compound as shown in Formula 2 in the polyester composition. Finally, there are more foreign matter in the polyester melt filter pressure test, the filter pressure difference ΔPa is relatively large, and the spinning is more unstable.

[0117] Comparative Examples 7 to 8

[0118] The amount of sulfonate added as shown in Formula 3 was changed, and other conditions were the same as in Example 1 to prepare a cationic dyeable polyester composition. Specific physical properties are shown in Table 4.

[0119] If the amount of sulfonate added is too low, the dyeability will be very poor and the desired color tone cannot be dyed. If the amount of sulfonate added is too high, the molecular weight of the obtained polyester composition will be small, the physical properties will be poor, and the strength of the yarn will be too low.

[0120] Comparative Example 9

[0121] No aliphatic dibasic acid or its esterified derivative was added, and the rest was the same as in Example 1. The specific physical properties are shown in Table 4.

[0122] Without adding aliphatic dibasic acids or their esterified derivatives, dyeability will decrease and hue value will be poor under the same dyeing temperature, and the strength of polyester will decrease.

[0123]

[0124]

[0125]

[0126]

Claims

1. A low temperature cationic dyeable polyester composition, mainly composed of aromatic dicarboxylic acid structural units and aliphatic diol structural units, characterized in that: The polyester composition contains a sulfonate group as shown in Formula 1, and the content of the sulfonate group as shown in Formula 1 accounts for 1000-5000 ppm of the total amount of the polyester composition in terms of sulfur element; the content of the compound as shown in Formula 2 is equivalent to less than 5.0 mol% of the total amount of the sulfonate group as shown in Formula 1 in terms of sulfur element; the polyester composition contains an aliphatic dibasic acid structural unit; the content of diethylene glycol in the polyester composition is 0.8-5.0 wt% relative to the total amount of the polyester composition; Formula 1, Formula 2, When preparing a low-temperature cationic dyeable polyester composition, firstly, an aromatic dicarboxylic acid or its esterified derivative and an aliphatic diol are subjected to an esterification or ester exchange reaction to obtain an oligomer, and then the obtained oligomer is subjected to a polymerization reaction to obtain a polyester composition, and an esterified liquid obtained by reacting a sulfonate compound as shown in Formula 3 with ethylene glycol, an aliphatic dicarboxylic acid or its esterified derivative and an alkali metal compound are added at any stage before the end of the polymerization reaction, the esterification reaction rate of the esterified liquid is above 95%, and the alkali metal compound is one or more of potassium hydroxide, sodium hydroxide, lithium hydroxide, potassium acetate, lithium acetate, potassium carbonate, and sodium hexametaphosphate. Formula 3, In Formulae 1 to 3, Y is an alkylene group having 2 to 20 carbon atoms, a phenylene group or an alkylenebenzene group, and Z and M are Li ions, Na ions or K ions, respectively.

2. The low temperature cationic dyeable polyester composition according to claim 1, characterized in that: The carbon number of the aliphatic dibasic acid structural unit is 4 to 10, accounting for 0.1 to 10.0 wt % of the polyester composition.

3. The low temperature cationic dyeable polyester composition according to claim 1 or 2, characterized in that: The content of the sulfonate group as shown in Formula 1 is 1000 to 3500 ppm based on the total amount of the polyester composition in terms of sulfur element.

4. The method for preparing the low-temperature cationic dyeable polyester composition according to claim 1, wherein an aromatic dicarboxylic acid or its esterified derivative is reacted with an aliphatic diol to obtain an oligomer through esterification or transesterification, and then the obtained oligomer is polymerized to obtain the polyester composition, wherein: At any stage before the end of the polymerization reaction, an esterification liquid obtained by reacting a sulfonate compound as shown in Formula 3 with ethylene glycol, an aliphatic dibasic acid or an esterification derivative thereof, and an alkali metal compound are added, wherein the esterification reaction rate of the esterification liquid is above 95%, and the alkali metal compound is one or more of potassium hydroxide, sodium hydroxide, lithium hydroxide, potassium acetate, lithium acetate, potassium carbonate, and sodium hexametaphosphate. Formula 3, In Formula 3, Y is an alkylene group, a phenylene group or an alkylenebenzene group having 2 to 20 carbon atoms, and Z is a Li ion, a Na ion or a K ion.

5. The method for preparing a low-temperature cationic dyeable polyester composition according to claim 4, characterized in that: The amount of the esterification liquid added is 1000 to 3500 ppm based on the total amount of the polyester composition, calculated as sulfur element in the esterification liquid.

6. The method for preparing a low-temperature cationic dyeable polyester composition according to claim 4, characterized in that: The carbon number of the aliphatic dibasic acid is 4 to 10, and the added amount of the aliphatic dibasic acid or its esterified derivative is 0.1 to 10.0 wt % of the total amount of the polyester composition.

7. The method for preparing the low temperature cationic dyeable polyester composition according to claim 4, 5 or 6, characterized in that: The alkali metal compound is one or more of lithium acetate, potassium hydroxide or sodium hydroxide.

8. The method for preparing the low temperature cationic dyeable polyester composition according to claim 4, 5 or 6, characterized in that: The added amount of the alkali metal compound is 10 to 1000 ppm based on the total amount of the polyester composition in terms of the alkali metal element.

9. Use of the low-temperature cationic dyeable polyester composition according to claim 1 in fibers.

Images