A production process for environmentally friendly ecological dark polylactic acid fabric

Abstract

The invention discloses a production process of an environmentally friendly ecological dark-colored polylactic acid fabric, which specifically comprises the following steps: S1, dyeing the polylactic acid fabric retaining the natural characteristics of the fiber; S2, performing reduction cleaning on the polylactic acid fabric dyed in step S1: first, dyeing and heat-insulating the polylactic acid fabric, then cooling the polylactic acid fabric to 50°C at a cooling rate of 2°C / min, draining the dye liquor, and then performing reduction cleaning and water washing; when performing reduction cleaning on the polylactic acid fabric, the amount of hydrosulfite used is 2-4 g / L, the reduction cleaning temperature is 70°C, the time is 20 minutes, and the pH value is 10-11; after completing the reduction cleaning, the polylactic acid fabric is washed once with MCL water in an acidic solution; S3, performing a shaping treatment on the polylactic acid fabric reduced in step S2: the shaping treatment temperature of the polylactic acid fabric is 110-120°C. The invention breaks the situation that there is no dark-colored pure spun polylactic acid fabric on the market, and provides more choices for the development of the polylactic acid fabric industry in textile and clothing applications.

Description

Technical Field

[0001] The present invention relates to the technical field of textile printing and dyeing, and more particularly to a production process of environmentally friendly ecological dark-colored polylactic acid fabric. Background Art

[0002] Polylactic acid fiber (PLA) is a high-performance aliphatic polyester polymer made by fermenting carbohydrates in crops and certain bacteria to form lactic acid monomers, cyclodimerizing the monomer lactic acid or directly polymerizing the lactic acid, and finally making a new type of fiber by spinning. However, although PLA fiber has good biocompatibility and biodegradability, it also has defects. There are two main reasons that restrict the widespread promotion and application of PLA fiber materials: ① low melting point of the fiber; ② alkali degradation problem. During the dyeing process of PLA fiber, it is easily affected by factors such as temperature, acidity, various auxiliaries, and dye structure and particle size. Although PLA fiber textiles and clothing have appeared on the market, due to the generally low color uptake of disperse dyes, the PLA fiber clothing on the market has more light colors and fewer dark colors, and the color vividness is not high. Therefore, how to improve the dye uptake and fastness of PLA fiber is the main research direction of modern materials and dyeing and finishing technology researchers.

[0003] In response to the technical bottlenecks faced by the industry, many technicians have conducted various research and attempts. For example, carrier dyeing, fiber modification, ultrasonic dyeing, supercritical carbon dioxide dyeing and other processes have emerged continuously. However, the actual effect is often only a small improvement in color, and the problem of dyeing depth cannot be completely solved from the root. There is still a lack of dark-colored PLA products on the market. Therefore, how to research and improve the mature dark and bright-colored production process of polylactic acid fabrics, and how to ensure that the knitted fabrics after dyeing and finishing can maintain good strength and fastness, is a technical problem that needs to be solved urgently. Summary of the Invention

[0004] In order to overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides a production process for environmentally friendly ecological dark-colored polylactic acid fabrics.

[0005] To achieve the above object, the present invention has the following innovative features: specifically comprising the following steps:

[0006] S1. Dyeing the polylactic acid fabric that retains the natural properties of the fiber. The dyeing parameters of the polylactic acid fabric are as follows:

[0007] a. Dye: Select a substance with a side chain polarity similar to that of polylactic acid molecules as the dye;

[0008] b. Dyeing carrier: Select anionic dyeing carrier - N-alkyl phthalamide derivative as the dyeing carrier, and the concentration of the dyeing carrier is 2%-5%;

[0009] c. Dyeing temperature: The maximum dyeing temperature of polylactic acid fabric is 100℃-115℃;

[0010] d. Dispersant: Choose fatty acid ester compounds as anionic dispersants;

[0011] S2. Perform reduction cleaning on the polylactic acid fabric dyed in step S1: first, complete the dyeing and heat preservation of the polylactic acid fabric. The dyeing and heat preservation time is as follows: the light-colored polylactic acid fabric is kept warm at the highest dyeing temperature for 30 minutes, and the dark-colored polylactic acid fabric is kept warm at the highest dyeing temperature for 45 minutes. Subsequently, the temperature is lowered to 50°C at a cooling rate of 2°C / minute, and then the dye liquor is drained and then reduced and washed. When the polylactic acid fabric is reduced and washed, the amount of hydrosulfite used is 2-4g / L, the reduction cleaning temperature is 70°C, the time is 20 minutes, and the pH is 10-11. After the reduction cleaning is completed, the polylactic acid fabric is washed with MCL in an acidic solution.

[0012] S3, performing a shaping treatment on the polylactic acid fabric that has completed the reduction cleaning in step S2: the temperature of the shaping treatment on the polylactic acid fabric is 110° C.-120° C.

[0013] Furthermore, the optimal concentration of the above-mentioned dyeing carrier is 4%.

[0014] Furthermore, the optimal maximum dyeing temperature of the polylactic acid fabric is 110°C.

[0015] Furthermore, the dyeing treatment steps are as follows: using acetic acid and sodium acetate buffer solution to adjust the pH value of the dye solution to 4-5, adding a dyeing carrier and a dispersant to the dye solution at 40°C and gradually heating it, heating the dye solution to 70°C at a heating rate of 2-3°C / min, keeping it warm for 15 minutes, and then heating it to 100-115°C at a heating rate of 1°C / min.

[0016] The technical effects and advantages of the present invention: The present invention bypasses the idea of ​​processing the polylactic acid fabric fiber itself, and conducts research from the aspects of dye structure screening and process design. While retaining the natural characteristics of the fiber itself, it improves the color depth and ensures the color fastness, and obtains pure polylactic acid fabric with relatively ideal depth, breaking the situation that there is no dark pure spun polylactic acid fabric on the market, and providing more choices for the development of the polylactic acid fabric industry in textile and clothing applications. DETAILED DESCRIPTION

[0017] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0018] The present invention provides a production process for environmentally friendly ecological dark-colored polylactic acid fabrics, which specifically comprises the following steps:

[0019] S1. Dyeing the polylactic acid fabric that retains the natural properties of the fiber. The steps of the dyeing process are as follows:

[0020] a. Use acetic acid and sodium acetate buffer solution to prepare the dye solution with a pH value of 4-5. Among them, the dye is selected from a substance with a side chain polarity close to that of the polylactic acid molecule. The polarity of this dye is close to that of polylactic acid, which is conducive to the large-scale adsorption of the dye on the polylactic acid fabric.

[0021] b. The dye liquor is gradually heated up after dyeing auxiliaries are added at 40°C. The dye carrier is an anionic dye carrier, N-alkylphthalamide derivative, with a concentration of 2%-5%. This dye carrier can expand the gap between polylactic acid molecules above the glass transition temperature, allowing more dyes to enter the fiber for combination. The concentration of the dye carrier is directly related to the color depth of the polylactic acid fabric.

[0022] c. Choose fatty acid ester compounds as dispersants. This type of dispersant can be adsorbed on the outer layer of dye particles to form a protective layer. Due to the repulsion of negative charges, the dye remains in a well-dispersed state, achieving a slow dyeing effect and reducing the chance of color fringing.

[0023] d. Heat the dye liquor to 70℃ at a heating rate of 2-3℃ / min and keep it warm for 15 minutes. This holding time setting can make the dye disperse as evenly as possible on the cloth surface. Finally, heat it to 100-115℃ at a heating rate of 1℃ / min. The selection of the highest temperature for dyeing is particularly important for the following reasons: For polylactic acid fabrics that retain the natural characteristics of the fiber, even under weakly acidic conditions, the highest temperature they can withstand is only 115℃. Once it exceeds 120℃, the hand feel will become hard, and the strength and elasticity will drop significantly, making it unsuitable for clothing. Therefore, polylactic acid fabrics can only be dyed below 120℃, but dyeing requires high temperature, and it is difficult to dye the fiber dark by low-temperature immersion dyeing. Under such contradictory conditions, choosing the right temperature can ensure both the quality of the polylactic acid fabric and the dyeing depth of the polylactic acid fabric.

[0024] S2. The polylactic acid fabric dyed in step S1 is subjected to reduction cleaning: after the polylactic acid fabric is dyed and heat-insulated, the light-colored polylactic acid fabric is dyed at a maximum dyeing temperature for 30 minutes, and the dark-colored polylactic acid fabric is dyed at a maximum dyeing temperature for 45 minutes. This dyeing and heat-insulating time can improve the dyeing quality and ensure the performance of the polylactic acid fabric. Subsequently, the temperature is lowered to 50°C at a cooling rate of 2°C / minute, and then the dye liquor is drained and then reduction cleaning and water washing are performed. When the polylactic acid fabric is reduced and cleaned, the amount of insurance powder used is 2-4g / L, the reduction cleaning temperature is 70°C, the time is 20min, and the pH is 10-11. After the reduction cleaning is completed, the polylactic acid fabric is washed with MCL water in an acidic solution. The whole process improves the washing fastness of the polylactic acid fabric.

[0025] S3, performing a shaping treatment on the polylactic acid fabric that has completed the reduction cleaning in step S2: the temperature of the shaping treatment on the polylactic acid fabric is 110° C.-120° C.

[0026] In the present invention, the present invention bypasses the idea of ​​processing the polylactic acid fabric fiber itself, and conducts research from the aspects of dye structure screening and process design. While retaining the natural characteristics of the fiber itself, it improves the color depth and ensures the dyeing fastness, and obtains pure polylactic acid fabric with relatively ideal depth, breaking the situation that there is no dark pure spun polylactic acid fabric on the market, and providing more choices for the development of the polylactic acid fabric industry in textile and clothing applications.

[0027] Examples 1 to 5 further illustrate the maximum dyeing temperature of the polylactic acid fabric of the present invention.

[0028] Example 1

[0029] In this embodiment, the maximum dyeing temperature of the polylactic acid fabric is 90° C. The bursting strength data of the polylactic acid fabric after dyeing in this embodiment are shown in Table 1.

[0030] Example 2

[0031] In this embodiment, the maximum dyeing temperature of the polylactic acid fabric is 100° C. The bursting strength data of the polylactic acid fabric after dyeing in this embodiment are shown in Table 1.

[0032] Example 3

[0033] In this embodiment, the maximum dyeing temperature of the polylactic acid fabric is 110° C. The bursting strength data of the polylactic acid fabric after dyeing in this embodiment are shown in Table 1.

[0034] Example 4

[0035] In this embodiment, the maximum dyeing temperature of the polylactic acid fabric is 115° C. The bursting strength data of the polylactic acid fabric after dyeing in this embodiment are shown in Table 1.

[0036] Example 5

[0037] In this embodiment, the maximum dyeing temperature of the polylactic acid fabric is 120° C. The bursting strength data of the polylactic acid fabric after dyeing in this embodiment are shown in Table 1.

[0038] Table 1 shows the test data of the bursting strength of polylactic acid fabrics at different maximum dyeing temperatures in Examples 1 to 5:

[0039]

[0040] Bursting strength represents the bursting strength and expansion of textile materials. Generally speaking, when the bursting strength reaches 250N or more, polylactic acid fabrics can be used in clothing. However, as can be seen from the above table, when the temperature reaches above 110°C, the bursting strength data of polylactic acid fabrics begins to drop sharply. When the maximum dyeing temperature is 115°C, the bursting strength of polylactic acid fabrics drops rapidly to 310N. The polylactic acid fabrics under this data will undergo subsequent reduction cleaning and shaping treatment. The polylactic acid fabrics will be continuously affected by the subsequent temperature and external mechanical stirring, which will cause the bursting strength of the final polylactic acid fabric to be difficult to meet the production requirements of clothing. Under the rule that the higher the temperature, the better the dyeing effect, 110°C is selected as the best maximum dyeing temperature.

[0041] After determining that 110° C. is the optimal maximum dyeing temperature for the polylactic acid fabric, Examples 6 to 9 further describe in detail the optimal dyeing carrier concentration for the polylactic acid fabric of the present invention.

[0042] Since polylactic acid fibers have the characteristics of strong hydrophobicity, high crystallinity and alignment, small fiber micro-voids and not easy to be wetted and expanded, it is difficult to allow the dye to smoothly enter the interior of the fiber in the form of a single molecule to complete the coloring, and conventional methods are difficult to carry out. In view of this, Examples 6 to 9 select wool, acrylic, polyester, nylon, cotton, and acetate, which have properties very close to those of polylactic acid fabrics, as test fabrics for staining tests.

[0043] Example 6

[0044] In this embodiment, the dyeing carrier concentration of the polylactic acid fabric is 2%. Accordingly, the staining data of the test fabric after dyeing is shown in Table 2.

[0045] Example 7

[0046] In this embodiment, the dyeing carrier concentration of the polylactic acid fabric is 3%. Accordingly, the staining data of the test fabric after dyeing is shown in Table 2.

[0047] Example 8

[0048] In this embodiment, the dyeing carrier concentration of the polylactic acid fabric is 4%. Accordingly, the staining data of the test fabric after dyeing is shown in Table 2.

[0049] Example 9

[0050] In this embodiment, the dyeing carrier concentration of the polylactic acid fabric is 5%. Accordingly, the staining data of the test fabric after dyeing is shown in Table 2.

[0051] Table 2 shows the test data of different test fabrics at different dyeing carrier concentrations in Example 9 to Example 9:

[0052]

[0053] Combining the test results of Examples 6 to 9, when specifically applied to polylactic acid fabrics, the following conclusions can also be drawn: the larger the amount of dyeing carrier used, the darker the color. When the carrier exceeds 4%, the color depth tends to decrease. This is related to the excessive amount of dyeing carrier, which occupies the end groups on the fabric fibers and some of which can be directly combined with the dye. Moreover, when the amount of dyeing carrier is too large, the overall fastness tends to decrease. Combining the above tests, it is determined that the optimal amount of dyeing carrier for polylactic acid fabrics is 4%.

[0054] In summary, the present invention studies and discovers high-coloring rate dyes for polylactic acid fiber fabrics, tests and screens supporting auxiliaries with good dyeing performance at home and abroad, selects dyes with good color fastness, bright color, and complete color spectrum to cooperate with each other, and at the same time, through theoretical research on the dyeing process, dyeing mechanism, dyeing thermodynamics and kinetics of polylactic acid fiber fabrics, combined with the actual situation of textile auxiliaries and traditional dyeing and finishing equipment, according to the process tested and solidified by the present invention, the black, bright red, navy blue and other colors produced can reach level 4 or above in color fastness to 40-degree soap washing, which provides a new direction for the industrialization and promotion of polylactic acid fiber and breaking through the technical bottleneck of dyeing. Compared with the process level of the same industry, the polylactic acid fabric produced by the present invention has a qualitative leap and breakthrough in color depth improvement.

[0055] Finally, a few points should be explained: First, in the description of this application, it should be noted that, unless otherwise specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense, and may refer to mechanical or electrical connections, internal communication between two components, or direct connection. "Up," "down," "left," and "right" are only used to indicate relative positional relationships. When the absolute positions of the objects being described change, the relative positional relationships may also change.

[0056] Secondly: In the embodiments disclosed in the present invention, only the structures related to the embodiments disclosed in the present invention are involved. Other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of the present invention can be combined with each other;

[0057] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A production process for environmentally friendly dark-colored polylactic acid fabrics, characterized by: The specific steps include: S1. Dyeing the polylactic acid fabric that retains the natural properties of the fiber. The dyeing parameters of the polylactic acid fabric are as follows: a. Dye: Select a substance with a side chain polarity similar to that of polylactic acid molecules as the dye; b. Dyeing carrier: An anionic dyeing carrier, N-alkyl phthalamide derivative, is selected as the dyeing carrier, and the concentration of the dyeing carrier is 2%-5%; c. Dyeing temperature: The maximum dyeing temperature of the polylactic acid fabric is 100°C-115°C; d. Dispersant: Select fatty acid ester compounds as anionic dispersants; S2. Perform reduction cleaning on the polylactic acid fabric dyed in step S1: first, perform dyeing and heat preservation on the polylactic acid fabric, and the dyeing and heat preservation time is as follows: the light-colored polylactic acid fabric is dyed for 30 minutes at the highest dyeing temperature, and the dark-colored polylactic acid fabric is dyed for 45 minutes at the highest dyeing temperature. Subsequently, the fabric is cooled to 50°C at a cooling rate of 2°C / minute, and then the dye liquor is drained and then reduced and washed. When the polylactic acid fabric is reduced and washed, the amount of hydrosulfite used is 2-4g / L, the reduction cleaning temperature is 70°C, the time is 20 minutes, and the pH is 10-11. After the reduction cleaning is completed, the polylactic acid fabric is washed with MCL in an acidic solution. S3, performing a shaping treatment on the polylactic acid fabric after the reduction cleaning in step S2: the temperature of the shaping treatment on the polylactic acid fabric is 110° C.-120° C.; The optimal concentration of the dye carrier is 4%; The optimal maximum dyeing temperature of the polylactic acid fabric is 110°C; The dyeing process comprises the following steps: using acetic acid and sodium acetate buffer solution to adjust the pH value of the dye solution to 4-5, adding a dyeing carrier and a dispersant to the dye solution at 40°C, gradually heating the dye solution to 70°C at a heating rate of 2-3°C / min, keeping the temperature for 15 minutes, and then heating the dye solution to 100-115°C at a heating rate of 1°C / min.

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