陳軍武 王其 盧雨正
摘要:
針對PLA纖維阻燃性差的問題,文章采用環(huán)磷酸酯阻燃劑對PLA/膠絲機(jī)織彈性帶進(jìn)行阻燃改性整理,探討了阻燃劑質(zhì)量濃度、浸漬溫度和浸漬時(shí)間對彈性帶阻燃性能的影響,并設(shè)計(jì)了正交試驗(yàn)和單因素優(yōu)化試驗(yàn)對阻燃浸漬工藝進(jìn)行優(yōu)化。結(jié)果表明:最優(yōu)的阻燃浸漬工藝條件為阻燃劑質(zhì)量濃度250 g/L、浸漬溫度50 ℃、浸漬時(shí)間2 h。經(jīng)該工藝處理后,機(jī)織彈性帶的阻燃性能達(dá)到FAR 25.853—1995美國航空材料防火檢測標(biāo)準(zhǔn),表現(xiàn)出良好的阻燃效果。
關(guān)鍵詞:
PLA纖維;機(jī)織彈性帶;阻燃整理;正交試驗(yàn);單因素試驗(yàn);阻燃性能
中圖分類號: TS195.5
文獻(xiàn)標(biāo)志碼: A
文章編號: 10017003(2022)02001205
引用頁碼: 021102
DOI: 10.3969/j.issn.1001-7003.2022.02.002(篇序)
收稿日期: 20210601;
修回日期: 20211213
基金項(xiàng)目:
作者簡介: 陳軍武(1996),男,碩士研究生,研究方向?yàn)榧徔椘返拈_發(fā)與功能整理。通信作者:盧雨正,副研究員,LuYz@jiangnan.edu.cn。
彈性帶又稱松緊帶、游泳帶,是含橡膠絲或乳膠絲的彈性織物,通常作為紡織輔料中的緊固性產(chǎn)品廣泛應(yīng)用于服裝、家具、醫(yī)療、器械、玩具、汽車安全帶等領(lǐng)域,屬于織帶行業(yè)生產(chǎn)的大類品種之一[1]。機(jī)織彈性帶的經(jīng)緯紗一般選用棉或滌綸,在經(jīng)向搭配一定的橡膠絲提高彈性后,可以通過設(shè)計(jì)平紋、斜紋、提花等不同的組織結(jié)構(gòu)擴(kuò)展使用范圍[2]。
近年來,紡織品的阻燃性和環(huán)保性越發(fā)受到行業(yè)和消費(fèi)者的重視,織帶產(chǎn)品被要求有一定的阻燃和環(huán)保作用,但是目前彈性帶在這方面的研究相對較少。聚乳酸纖維(Polylactic Acid,PLA)因其原料可再生和可生物降解等特點(diǎn)被稱為21世紀(jì)的綠色環(huán)保纖維,其制品廢棄后在自然條件下可降解成乳酸、二氧化碳和水,不污染環(huán)境[3]。此外,PLA纖維的物理機(jī)械性能與滌綸、錦綸相似,結(jié)構(gòu)穩(wěn)定且加工性能良好。PLA纖維的極限氧指數(shù)(LOI)有26%,比棉和滌綸高,但只是在一段時(shí)間內(nèi)起到自熄的效果,并不具備良好的阻燃性,若用在阻燃防火產(chǎn)品上則需要進(jìn)行額外的阻燃處理[4]。磷系阻燃劑具有低毒、低煙和阻燃效率高的特點(diǎn),是取代傳統(tǒng)鹵系阻燃劑的重
點(diǎn)研究對象[5-6]。國內(nèi)外學(xué)者在磷系阻燃PLA方面做了大量研究,Chen Yajun等[7]和劉婷[8]研究發(fā)現(xiàn),不同分子結(jié)構(gòu)的磷酸酯阻燃劑通過改變PLA材料燃燒時(shí)的成炭速率和形態(tài),從而影響其阻燃性能。Liao[9]等制備出一種含磷-氮-硅元素的阻燃PLA復(fù)合材料,分析其阻燃機(jī)理發(fā)現(xiàn),硅元素的存在形成了石墨殘?zhí)拷Y(jié)構(gòu),有效阻止了材料的燃燒。
根據(jù)PLA纖維和膠絲的特性,本文采用環(huán)磷酸酯阻燃劑,通過浸漬方式對PLA/膠絲彈性帶進(jìn)行阻燃整理,根據(jù)正交試驗(yàn)和單因素優(yōu)化試驗(yàn)得到最佳的阻燃浸漬整理工藝。
1 試 驗(yàn)
1.1 試樣準(zhǔn)備
經(jīng)紗為333.33 dtex/288 f PLA與40號阻燃膠絲(常州振華服飾材料有限公司)按照2︰1配合使用,緯紗采用333.33 dtex/288 f PLA紗線。通過萬利達(dá)窄幅織物機(jī)織成緯密為172.4根/10 cm的PLA/膠絲機(jī)織彈性帶,用于阻燃性能測試。彈性帶的基本物理機(jī)械性能如表1所示。
1.2 試 劑
環(huán)磷酸酯阻燃劑(上海享金化工有限公司),異丙醇(分析純,江蘇彤晟化學(xué)試劑有限公司),片狀NaOH(分析純,無錫新葉臨化工貿(mào)易有限公司)。
1.3 設(shè) 備
HH-6數(shù)顯恒溫水浴鍋(上海力辰邦西儀器科技有限公司),881-TG型熱風(fēng)循環(huán)干燥箱(吳江市創(chuàng)新烘箱制造有限公司),AI-7000S拉力強(qiáng)度試驗(yàn)機(jī)(高鐵檢測儀器(東莞)有限公司),XJ830等速伸長CRE拉伸試驗(yàn)儀(上海湘杰儀器儀表科技有限公司),YG815垂直法織物阻燃性能測試儀(山東安丘江北紡織儀器有限公司),V5M6/50萬利達(dá)窄幅織物機(jī)(萬利達(dá)集團(tuán)有限公司)。
1.4 阻燃整理工藝
阻燃整理液由環(huán)磷酸酯阻燃劑、異丙醇和水經(jīng)NaOH調(diào)節(jié)pH值至6.5配制而成,其中織物平方米質(zhì)量與水的用量比為1︰10。把PLA/膠絲機(jī)織彈性帶放入配制好的阻燃整理液中進(jìn)行浸漬處理,浸漬結(jié)束后,在100 ℃烘干3 min,冷卻后在165 ℃焙烘30 s。
1.5 測 試
采用YG815垂直法織物阻燃性能測試儀對織帶的阻燃性能進(jìn)行測試,試驗(yàn)標(biāo)準(zhǔn)參照標(biāo)準(zhǔn)FAR 25.853(a)—1995《航空材料防火檢測標(biāo)準(zhǔn)》。測試要求:彈性帶長度300 mm,用試樣夾固定好后點(diǎn)燃試樣,燃燒12 s后離開火焰,待試樣燃燒停止后,量取并記錄織帶的燃燒長度、余焰時(shí)間和滴焰時(shí)間,每組樣品測試5次取平均值??紤]到余焰時(shí)間和滴焰時(shí)間的測試精度問題,本文采用平均燃燒長度作為指標(biāo)來評價(jià)彈性帶的阻燃性能,當(dāng)平均燃燒長度<20.3 cm[10]時(shí)認(rèn)為織帶具有阻燃效果。
2 結(jié)果與分析
2.1 正交試驗(yàn)
通過設(shè)計(jì)正交試驗(yàn),探究阻燃劑質(zhì)量濃度、浸漬溫度和浸漬時(shí)間對彈性帶阻燃性能的影響。由于異丙醇在試驗(yàn)中僅作為增強(qiáng)劑,并不起阻燃作用,因此在本試驗(yàn)中,把阻燃劑和異丙醇的質(zhì)量濃度看作是一個(gè)因素,異丙醇相對阻燃劑質(zhì)量分?jǐn)?shù)為12%,恒定不變。采用L9(33)正交表進(jìn)行試驗(yàn),因素及水平見表2,各試驗(yàn)方案工藝條件及結(jié)果見表3,極差分析結(jié)果見表4。
從表4的極差分析可知,影響PLA/膠絲機(jī)織彈性帶平均燃燒長度指標(biāo)的主次因素分別為:阻燃劑質(zhì)量濃度>浸漬時(shí)間>浸漬溫度,對應(yīng)的較優(yōu)阻燃浸漬工藝為A3B3C2,即阻燃劑質(zhì)量濃度225 g/L、浸漬溫度50 ℃、浸漬時(shí)間2 h。
2.2 單因素優(yōu)化試驗(yàn)
從正交試驗(yàn)結(jié)果可知,因素A和因素B都是在最高點(diǎn)處獲得較好的阻燃效果,而因素C在中間2 h處取得較優(yōu)的阻燃效果。因此,固定因素C,單獨(dú)對因素A和因素B進(jìn)行優(yōu)化實(shí)驗(yàn)。
2.2.1 阻燃劑質(zhì)量濃度對阻燃性能的影響
在浸漬溫度為50 ℃、浸漬時(shí)間為2 h的條件下,通過改變阻燃劑質(zhì)量濃度進(jìn)行優(yōu)化試驗(yàn),結(jié)果如圖1所示。
由圖1可知,阻燃劑質(zhì)量濃度對PLA/膠絲彈性帶的阻燃性能有顯著影響。當(dāng)阻燃劑質(zhì)量濃度在200~250 g/L時(shí),阻燃效果明顯。隨著阻燃劑質(zhì)量濃度的增加,與織帶結(jié)合的阻燃劑越多,這些阻燃劑受熱時(shí)會(huì)生成含氧酸和偏磷酸聚合物覆蓋在纖維表面,起到減少放熱量和隔氧作用,從而有效抑制燃燒反應(yīng)的進(jìn)行;當(dāng)阻燃劑質(zhì)量濃度超過250 g/L后,阻燃效果降低,這是因?yàn)榭棊c阻燃劑之間已經(jīng)達(dá)到動(dòng)態(tài)吸附平衡,即使繼續(xù)增加阻燃劑質(zhì)量濃度,新結(jié)合的阻燃劑也只能附著在纖維表面,燃燒時(shí)阻燃劑分解的熱量會(huì)加速纖維的熔融分解,從而降低織帶的阻燃性能[11]。根據(jù)單因素試驗(yàn)結(jié)果,阻燃劑的最優(yōu)質(zhì)量濃度為250 g/L。
2.2.2 浸漬溫度對阻燃性能的影響
在阻燃劑質(zhì)量濃度為250 g/L、浸漬時(shí)間為2 h的條件下改變浸漬溫度進(jìn)行優(yōu)化試驗(yàn),結(jié)果如圖2所示。
由圖2可知,浸漬溫度為50 ℃時(shí)織帶的阻燃效果最好,超過此溫度后,織帶的阻燃性能有所下降。這是因?yàn)楦邷仄茐牧俗枞紕┑慕Y(jié)構(gòu),導(dǎo)致與織帶結(jié)合的部分阻燃劑沒有發(fā)揮作用,甚至加速了燃燒過程,最終阻燃效果降低。
結(jié)合圖3可知,膠絲的力學(xué)性能受溫度影響很大[12]。在55 ℃時(shí),彈性帶的強(qiáng)力損失超過了5%,考慮到高溫焙烘后其強(qiáng)力損失會(huì)進(jìn)一步增加,優(yōu)選最佳浸漬溫度為50 ℃。
2.3 阻燃性能分析
根據(jù)正交試驗(yàn)和單因素試驗(yàn)結(jié)果得到最優(yōu)的阻燃工藝為:阻燃劑質(zhì)量濃度250 g/L、浸漬溫度50 ℃、浸漬時(shí)間2 h。在該工藝條件下,測試PLA/膠絲彈性帶的阻燃性能,結(jié)果如表5所示。
從表5可知,原PLA彈性帶在垂直燃燒測試時(shí),三項(xiàng)指標(biāo)均不能通過;最優(yōu)工藝整理的PLA彈性帶平均燃燒長度只有3.9 cm,余焰時(shí)間0.7 s,表明彈性帶在離開火源時(shí)能迅速自熄且無熔滴產(chǎn)生,能夠通過美國航空材料防火檢測標(biāo)準(zhǔn)FAR 25.853—1995的阻燃測試。
3 結(jié) 論
本文以PLA纖維和阻燃膠絲為原料織造了緯密為172.4根/10 cm的機(jī)織彈性帶。采用浸漬方法對織帶進(jìn)行阻燃整理,并通過正交試驗(yàn)和單因素優(yōu)化試驗(yàn)獲得最優(yōu)的阻燃浸漬工藝:阻燃劑質(zhì)量濃度250 g/L、浸漬溫度50 ℃和浸漬時(shí)間2 h。經(jīng)上述工藝整理后,PLA/膠絲機(jī)織彈性帶的阻燃指標(biāo)能夠達(dá)到FAR 25.853美國航空材料防火檢測標(biāo)準(zhǔn),表現(xiàn)出良好的阻燃效果。
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Abstract:
Elastic belt, also known as elastic band, is a high-elasticity fabric usually made of polyester, polyamide and rubber silk, and belongs to one of the major categories of ribbon industry production. It is widely used as a necessary auxiliary material for sewing traditional sports goods, industrial goods and household goods and is also mainly used as a fastening material for cuffs, shoe linings, leg openings, hat linings, collars, waistbands and other places close to the human body. At present, most of the functional elastic belt products on the market are wet permeable, antibacterial, comfortable, UV resistant and yellowing resistant, etc. However, such products are used in some high-temperature operations, transportation tools, medical and health environment and laboratories, etc., which may easily cause fire accidents. Polylactic acid (PLA) is a green and environmentally friendly fiber. Despite its poor flame retardancy, it has the characteristics of renewable and biodegradable raw materials. It can be made into elastic belt products for flame-retardant modification, which can not only improve its use security, but also can be degraded into lactic acid, CO2 and water under natural conditions after being discarded, without pollution to the environment.
In order to improve the flame retardancy of environmentally friendly polylactic acid (PLA) elastic belt, the biodegradable characteristics of PLA fiber were studied to interweave woven elastic belt with flame retardant rubber silk. Firstly, a cyclic phosphate ester flame retardant with low toxicity, low smoke and high flame retardant efficiency was used to conduct flame retardant modification and finishing of PLA/plastic silk woven elastic belt by impregnation baking process. On this basis, the effects of the concentration of flame retardant, impregnation temperature and impregnation time on the flame retardancy of elastic belt were discussed. Among them, a three-level three-factor orthogonal test was designed with the average burning length as the evaluation index through range analysis method. It was found that the primary and secondary factors affecting the flame retardant performance of the elastic belt were: flame retardant concentration>impregnation time>impregnation temperature. The flame retardant effect was good when flame retardant concentration and impregnation temperature were at level 3, while the flame retardant effect was the optimal when the impregnation time was at level 2. Based on this, a single factor optimization experiment was performed to explore the influence of the separate change of flame retardant concentration on the average burning length of the elastic belt, then to discuss the variation rules of the average burning length and strength loss of the elastic belt at different impregnation temperatures, and finally to obtain the optimal process conditions of flame retardant impregnation and finishing. On this basis, the article adopted orthogonal experiment, range analysis and single factor experiment to optimize the impregnation, baking and flame-retardant finishing process of PLA/plastic silk woven elastic belt. The study found that the optimal flame retardant impregnation process conditions are: flame retardant concentration 250 g/L, impregnation temperature 50 ℃, impregnation time 2 h. Through the above process finishing, the flame retardant index of PLA/plastic silk woven elastic belt reached FAR 25.853-1995 American aviation material fire test standard, and exhibited excellent flame retardant effect.
The relationship between the impregnation and baking finishing process conditions and the flame retardant performance of PLA/plastic silk woven elastic belt can provide revelations for the R&D of flame-retardant elastic belt products. From the perspective of product application, when used in transportation vehicles, sitting bedding, fire-fighting clothing, and software fasteners such as equipment, experimental clothing and equipment, and medical clothing and equipment, it is expected to effectively reduce potential safety hazards, without pollutions to the environment after being discarded. The research results can provide referential suggestions for the design and development of flame-retardant and environmentally friendly elastic belt products.
Key words:
PLA fiber; woven elastic band; flame retardant finishing; orthogonal test; single factor experiment; flame retardant performance