WO2018184146A1 - 氰乙基纤维素的制备方法 - Google Patents

氰乙基纤维素的制备方法 Download PDF

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WO2018184146A1
WO2018184146A1 PCT/CN2017/079429 CN2017079429W WO2018184146A1 WO 2018184146 A1 WO2018184146 A1 WO 2018184146A1 CN 2017079429 W CN2017079429 W CN 2017079429W WO 2018184146 A1 WO2018184146 A1 WO 2018184146A1
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mixture
cellulose
ethanol
reaction
stirring
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PCT/CN2017/079429
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French (fr)
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钟玲珑
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深圳市佩成科技有限责任公司
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
    • C08B11/00—Preparation of cellulose ethers
    • C08B11/02—Alkyl or cycloalkyl ethers
    • C08B11/04—Alkyl or cycloalkyl ethers with substituted hydrocarbon radicals
    • C08B11/14—Alkyl or cycloalkyl ethers with substituted hydrocarbon radicals with nitrogen-containing groups
    • C08B11/155—Alkyl or cycloalkyl ethers with substituted hydrocarbon radicals with nitrogen-containing groups with cyano groups, e.g. cyanoalkyl ethers

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  • the invention relates to a preparation method of cyanoethyl cellulose, belonging to the field of preparation of high dielectric materials.
  • High dielectric materials are a widely used insulating material, and because of its excellent electrical storage and uniform electric field properties, it has very important applications in the electronics, motor and cable industries. With the development of high-performance and size miniaturization of many important electronic devices such as capacitors, resonators, filters, and memories, high dielectric materials are receiving more and more attention. At present, high dielectric materials are widely used. Traditional ceramic materials have high brittleness, high processing temperature and high loss; polymer materials have excellent processing properties, but generally have a low dielectric constant.
  • cyanoethyl cellulose has attracted attention due to its excellent physical and chemical properties.
  • An important factor affecting the performance of cyanoethyl groups is the degree of substitution.
  • Partially cyanoethylated cellulose exhibits good heat resistance, antimicrobial properties, mechanical properties and low moisture regain.
  • Highly substituted cyanoethyl cellulose has outstanding dielectric properties, high dielectric constant and low dielectric loss, and can be used for dielectric materials.
  • cyanoethyl cellulose can form cholesteric liquid crystals in a high concentration organic solvent.
  • cyanoethyl cellulose prepared by the two conventional methods is difficult to process, has a large loss, and cannot be uniformly and efficiently carried out.
  • the object of the present invention is to overcome the deficiencies of materials prepared by conventional preparation methods and to provide a cyanoethyl group.
  • a method of preparing cellulose In order to achieve the above object, the present invention adopts the following technical solutions:
  • the invention provides a preparation method of cyanoethyl cellulose, comprising the following steps:
  • Step 1 alkalizing the cellulose, weighing 5 g of cellulose, adding 25 g of a mixture of isopropanol and ethanol, and adding 25 g of different concentrations of sodium hydroxide solution, and stirring;
  • Step 2 Cyanoethylation of cellulose, the mixture of step 1 is subjected to suction filtration, a mixture of acrylonitrile and dichloromethane is added, and stirring is carried out, then the temperature is raised in stages, and the reaction is carried out. The amount of acetic acid terminates the reaction;
  • Step 3 The mixture obtained in the second step is subjected to precipitation, washed with ethanol or deionized water and dried.
  • the ratio of isopropanol to ethanol in the mixture of isopropanol and ethanol in the above step 1 is 3:7.
  • the stirring in the above step 1 is carried out at room temperature, and the mixture is stirred for 2 hours to be dissolved and alkalized.
  • the mixture is taken out and pressed with a suction device, and then kneaded and dispersed into small particles.
  • the stirring in the above step 2 is carried out at room temperature, and the temperature is raised to 50 ° C in stages to carry out a reaction for two hours.
  • the mixture is slowly poured into a volume concentration of 75% ethanol for precipitation.
  • step three it is washed three times with ethanol or deionized water, and dried at 60 °C.
  • the preparation method of the cyanoethyl cellulose provided by the invention has simple preparation process and good reaction time control, and CEC has high tensile strength and small elongation at break, no yield point, and has very high Good rigidity.
  • Figure 1 is a schematic view showing the comparison of the infrared spectrum of the present invention with cellulose
  • Figure 2 is a schematic view of an X-ray diffraction pattern of the present invention.
  • FIG. 3 is a schematic diagram showing the relationship between the CEC reaction time and the degree of substitution according to the present invention.
  • FIG. 4 is a schematic diagram of a TG curve of a CEC of the present invention.
  • Figure 5 is a schematic view showing the mechanical stretching curve of the CEC of the present invention.
  • Fig. 6 is a graph showing the relationship between the dielectric constant and the frequency of the CEC of the present invention.
  • Fig. 7 is a graph showing the dielectric loss of the CEC of the present invention as a function of frequency.
  • the present invention provides a method for preparing cyanoethyl cellulose.
  • the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
  • the mixture was taken out and pressed with a suction filter, and then kneaded and dispersed into small particles.
  • a mixture of acrylonitrile and dichloromethane was added to the three-necked flask, and the wet material was slowly added. After the addition, the mixture was stirred at room temperature for 5 min, then heated to 50 ° C in stages, and reacted for two hours. After the end of etherification, the reaction was quenched with the corresponding amount of acetic acid.
  • the mixture was slowly poured into a volume concentration of 75% ethanol for precipitation. It was then washed three times with ethanol or deionized water and dried at 60 °C.
  • the wave number ranges from 4000 to 400 cm -1 .
  • the product was subjected to elemental analysis using an elemental analyzer.
  • the degree of substitution is calculated based on the measured nitrogen content, and the formula is as follows:
  • the CEC film is made into a small circular circle of 0.3 cm, and as a dielectric material, the silver paste conductive paste is coated on both surfaces, and dried to obtain a direct Sample material for performance testing on an impedance analyzer.
  • Scan analysis test at different frequencies to obtain a series of capacitance values, using the relationship between capacitance and dielectric constant ⁇ (c * d) / (A * ⁇ 0), where c is the capacitance of the film material, d is the film material The thickness, ⁇ 0 is a vacuum dielectric constant of 8.8538 ⁇ 10-12 Farad / F, A is the area of the film, and the dielectric constant value is calculated.
  • cyanoethyl cellulose has a strong characteristic absorption band at 2250 cm -1 due to the stretching vibration of the -CN group.
  • the absorption band broadening strength is weakened after the cellulose is etherified.
  • the CH bending shock peak at 1200-1400 cm -1 is shifted to the low frequency direction by the influence of -CN, which indicates that a part of the -OH group has become a -OCH 2 CH 2 CN group after cyanoethylation.
  • the cyanoethyl cellulose has a large diffraction peak near 20° and is relatively wide, which is a diffuse scattering peak. It is indicated that the cyanoethylation reaction has a great damage to the crystallization of cellulose, resulting in microcrystalline and amorphous structures.
  • the synthesis of CEC is alkalized and etherified.
  • the cellulose expands, the hydrogen bond is destroyed, the lateral linkage of the structure is weakened, the orientation of the molecular structure is deteriorated, and the etherification is introduced into the cyanide.
  • the molecular spacing becomes larger, the interplanar spacing becomes wider, the crystallization zone is destroyed, the crystallinity is lowered, the macromolecule exhibits a large amorphous shape, and the X-ray diffraction peak exhibits a large diffuse scattering peak.
  • the X-ray diffraction pattern of the control product and the raw material cellulose showed that the characteristic peak of cellulose at 2 ⁇ of 22.6° was significantly reduced, indicating that the CEC reaction proceeded relatively completely and the cellulose crystal form was destroyed.
  • Figure 4 is a graph showing the thermal weight loss curve and the thermal weight loss differential curve of CEC under a nitrogen atmosphere.
  • the elongation at break of CEC was 4.22%
  • the tensile strength was 51.35 MPa
  • the tensile elastic modulus was 2190.6 MPa. It has high tensile strength and small elongation at break, no yield point, and is a strong and strong material.
  • the CEC film is essentially a brittle fracture during the stretching process, that is, the fracture of the material before it yields.
  • the breaking strength of a polymer is mainly determined by molecular weight, crosslinking, crystallization, orientation, and intermolecular forces. When the fracture strength is actually measured, its size is also strongly dependent on the strain rate and temperature.
  • the cellulose skeleton chain is relatively rigid, and a relatively large cyanoethyl group is introduced.
  • the rigidity of the molecular chain is increased, and the intramolecular rotation is difficult, so that the flexibility of the molecular chain is poor, and brittle fracture is likely to occur during stretching.
  • the dielectric constant and dielectric loss of CEC at different frequencies are shown in Figures 6 and 7.
  • the dielectric constant of CEC is 15; as the frequency increases, the dielectric constant decreases.
  • the dielectric constant of CEC drops to 7, and at this frequency, the dielectric constant of most polymers is 5 or less.
  • the dielectric loss represents the thermal energy loss of the product under an applied electric field, typically expressed as the dielectric loss tangent tan ⁇ .
  • the dielectric loss value of CEC at 1MHz is 0.18, and the dielectric loss tangent of the product is small, indicating that the thermal energy loss of the product under the applied electric field is small.
  • the preparation method of the cyanoethyl cellulose provided by the invention has simple preparation process and good reaction time control, and CEC has high tensile strength and small elongation at break, no yield point, and has very high Good rigidity.

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Abstract

本发明提供了一种氰乙基纤维素的制备方法，包括步骤一、对纤维素进行碱化，称取纤维素，加入异丙醇与乙醇的混合液，再加入不同浓度的氢氧化钠溶液，并进行搅拌；步骤二、对纤维素进行氰乙基化，将步骤一的混合物进行抽滤压榨，加入丙烯腈和二氯甲烷的混合液，并进行搅拌，然后分阶段升温、反应，醚化结束后用相应量的乙酸终止反应；步骤三、将步骤二获得的混合物进行沉析，用乙醇或去离子水洗涤并干燥。相比现有技术，本发明提供的氰乙基纤维素的制备方法，制备工艺简单，反应时间很好控制，CEC具有高的拉伸强度和小的断裂伸长率，没有屈服点，具有很好的刚性。

Description

氰乙基纤维素的制备方法 技术领域
本发明涉及一种氰乙基纤维素的制备方法，属于高介电材料制备领域。
背景技术
高介电材料是一种应用前景非常广泛的绝缘材料，由于它有着很好的储存电能和均匀电场的性能，因而在电子、电机和电缆行业中都有非常重要的应用。随着电容器、谐振器、滤波器、存储器等众多重要电子器件向高性能化和尺寸微型化方向的发展，高介电材料受到越来越多的关注。目前，高介电材料广泛应用，传统的陶瓷材料脆性大、加工温度高、损耗大；聚合物材料具有优良的加工性能，但是通常介电常数又较低。
近年来，许多具有自由羟基的高聚物的氰乙基化研究已广泛开展，其中包括纤维素、乙基纤维素、壳聚糖、木质素等。在这些氰乙基化材料中，氰乙基纤维素由于其卓越的物理及化学性质而备受关注。影响氰乙基性能的一个重要因素就是取代度。部分氰乙基化的纤维素显示出良好的抗热性能、抗微生物性能、力学性能以及低回潮率。高取代的氰乙基纤维素的介电性能比较突出，具有较高的介电常数及较低的介电损耗，可用于介电材料。此外，氰乙基纤维素在高浓度有机溶剂中，还可形成胆甾相液晶。
技术问题
目前，氰乙基纤维素的合成方法主要是两种：均相法和非均相法。但这两种传统方法制备出的氰乙基纤维素加工难度高、损耗非常大、不能够均匀有效地进行。
问题的解决方案
技术解决方案
鉴于上述现有技术的不足之处，本发明的目的在于提供一种氰乙基纤维素的制备方法。
本发明的目的是为了克服传统制备方法制备的材料的不足，提供了一种氰乙基 纤维素的制备方法。为了达到上述目的，本发明采取了以下技术方案：
本发明提供了一种氰乙基纤维素的制备方法，包括以下步骤：
步骤一、对纤维素进行碱化，称取5g纤维素，加入异丙醇与乙醇的混合液25g，再加入不同浓度的氢氧化钠溶液25g，并进行搅拌；
步骤二、对纤维素进行氰乙基化，将步骤一的混合物进行抽滤压榨，加入丙烯腈和二氯甲烷的混合液，并进行搅拌，然后分阶段升温、反应，醚化结束后用相应量的乙酸终止反应；
步骤三、将步骤二获得的混合物进行沉析，用乙醇或去离子水洗涤并干燥。
优选的，上述步骤一中的异丙醇与乙醇的混合液中异丙醇与乙醇溶液比例为3∶7。
优选的，上所述步骤一中的搅拌是在室温下进行，搅拌2小时，进行溶解、碱化。
优选的，上述步骤二中将混合物取出并用抽滤装置压榨，之后捏碎分散成小颗粒物。
优选的，上述步骤二中搅拌在室温下进行，分阶段升温至50℃，反应两个小时。
优选的，上述步骤三中将混合物缓慢倒入体积浓度为75％乙醇中进行沉析。
优选的，上述步骤三中用乙醇或去离子水洗涤三次，并在60℃下干燥。
发明的有益效果
有益效果
相比现有技术，本发明提供的氰乙基纤维素的制备方法，制备工艺简单，反应时间很好控制，CEC具有高的拉伸强度和小的断裂伸长率，没有屈服点，具有很好的刚性。
对附图的简要说明
附图说明
图1为本发明与纤维素的红外图谱对比示意图；
图2为本发明X-射线衍射图谱示意图；
图3为本发明CEC反应时间与取代度的关系曲线示意图；
图4为本发明CEC的TG曲线示意图；
图5为本发明CEC的力学拉伸曲线示意图；
图6为本发明CEC的介电常数随频率变化的曲线示意图。
图7为本发明CEC的介电损耗随频率变化的曲线示意图。
发明实施例
本发明的实施方式
本发明提供一种氰乙基纤维素的制备方法，为使本发明的目的、技术方案及效果更加清楚、明确，以下参照附图并举实施例对本发明进一步详细说明。应当理解，此处所描述的具体实施例仅用以解释本发明，并不用于限定本发明。
本实施例提供的氰乙基纤维素的制备方法，具体包括以下步骤：
(1)纤维素的碱化
称取5g纤维素(摩尔取代度分别为M5，M15，M30)，放入250ml三口瓶中，加入异丙醇与乙醇的混合液25g(异丙醇与乙醇溶液比例为3∶7)，再加入不同浓度的氢氧化钠溶液25g。室温下搅拌2h，溶解、碱化。
(2)纤维素的氰乙基化：
将混合物取出并用抽滤装置压榨，之后捏碎分散成小颗粒物。向三口烧瓶中加入丙烯腈和二氯甲烷的混合液，将湿料缓慢加入。加完后先在室温下搅拌5min，然后分阶段升温至50℃，反应两个小时，醚化结束后用相应量的乙酸终止反应。
(3)沉析：
将混合物缓慢倒入体积浓度为75％乙醇中进行沉析。然后用乙醇或去离子水洗涤三次，并在60℃下干燥。
根据傅里叶红外光谱仪测试，波数范围为4000～400cm-1。采用溴化钾压片法进行红外分析。采用CuKa线，Ni滤波，λ＝1.54056×10-10m，扫描范围2θ＝6～70°)。
利用元素分析仪对产物进行元素分析。根据测得的含氮量计算取代度，公式如下：
Figure PCTCN2017079429-appb-000001
通过阻抗分析仪(配套的安捷伦介电测试夹具)进行测试；将CEC薄膜做成0.3cm的小圆形，作为电介质材料，将银浆导电胶涂覆在两个表面，干燥后得到可直接在阻抗分析仪上进行性能测试的样品材料。在不同的频率下进行扫描分析测试，得到一系列电容数值，利用电容与介电常数的关系ε＝(c*d)/(A*ε0)，其中c为薄膜材料的电容，d为薄膜材料的厚度，ε0为真空介电常数8.8538×10-12法拉/F，A为薄膜的面积，计算出介电常数数值。
由原料及醚化后的氰乙基纤维素的红外谱图图1可知，氰乙基纤维素在2250cm-1处有一强的特征吸收带，这是由于-CN基团的伸缩振动引起的。而在3400-3500cm-1处-OH的伸缩振动引起的的强吸收带，在纤维素被醚化后，吸收带变宽强度减弱。在1200-1400cm-1处的C-H弯曲震动峰因受到-CN影响向低频方向移动，这些都说明部分-OH基团经氰乙基化后已成为-OCH2CH2CN基团。
从图2可以看出，纤维素在2θ＝14.8°、16.4°、22.6°和35°有四个衍射峰，峰形较为尖锐，其结晶度为80％。氰乙基纤维素在20°附近都有较大的衍射峰，且比较宽，属漫散射峰。说明氰乙基化反应对纤维素的结晶有较大破坏，产生微晶和无定形结构。CEC的合成经过碱化、醚化反应，在碱化过程中纤维素要发生膨胀，氢键被破坏，其结构内部横向的联结消弱，分子结构的定向性变差；同时醚化引入氰乙基后，分子间距变大，晶面间距变宽，破坏结晶区，结晶度降低，大分子呈现较大的无定形，X-ray衍射峰呈现大的漫散射峰。对照产物和原料纤维素的X-射线衍射图谱可知，2θ为22.6°处的纤维素特征峰明显缩小，表明CEC反应均进行得比较完全，纤维素晶型被破坏。
由图3可知，CEC的取代度在反应初期随着反应时间的延长迅速增大，含氮量增加较快；但随着时间再增加到60min，反应速率逐渐缓慢，取代度增加幅度不是很大。继续增加反应时间，反应效果不明显并且副反应发生的可能性增大，所以反应时间控制在2小时比较适宜。在反应初期，随着时间的增加，纤维素和丙烯腈接触的机会加大，氰乙基不断地接到单元环上与纤维素发生反应，含氮量增加较快；一段时间后，单元环上被取代的羟基趋于饱和，未反应的羟基减 少，所以时间增加取代度增幅却比较低。
图4为CEC在氮气气氛下的热失重曲线和热失重微分曲线。通过查阅有关资料，可以知道在纯纤维素的热分析过程中，在310～350℃间，由于左旋葡萄聚糖的形成和挥发，纤维素会发生强的热裂解。由图可见，CEC的分解过程只有一个阶段，相应的在DTG图上只有一个峰，对应的分解温度为369℃。在热分解的过程中，当到达一定温度时，纤维素骨架结构被破坏，产物迅速发生热降解，在曲线上表现出质量的急剧下降。小分子侧链随纤维素骨架架构的破坏而断裂分解，在曲线上表现不明显，对产物的稳定性影响较小。
由图5可以看出，CEC的断裂伸长率为4.22％，拉伸强度为51.35MPa，拉伸弹性模量为2190.6MPa。它具有高的拉伸强度和小的断裂伸长率，没有屈服点，是刚而强的材料。CEC膜在拉伸过程中基本属于脆性断裂，即材料在出现屈服之前发生的断裂。高聚物的断裂强度主要决定于分子量、交联、结晶、取向和分子间作用力。实际测定断裂强度时，其大小也强度地依赖于应变速度和温度。纤维素骨架链刚性比较强，引入极性比较大的氰乙基基团，分子链刚性增加，分子内旋转困难，因而分子链的柔顺性较差，拉伸时容易发生脆性断裂。
CEC在不同频率下的介电常数和介电损耗见图6和图7。频率为100Hz时，CEC的介电常数是15；随着频率的增加，介电常数降低，1000Hz时，CEC的介电常数降至7，而此频率下，大多数聚合物的介电常数在5以下。
介电损耗表示产物在外加电场下的热能损耗，一般以介电损耗角正切tanδ表示。CEC在1MHz时的介电损耗值分别为0.18，产物的介电损耗角正切较小，说明产物在外加电场下的热能损耗较小。
相比现有技术，本发明提供的氰乙基纤维素的制备方法，制备工艺简单，反应时间很好控制，CEC具有高的拉伸强度和小的断裂伸长率，没有屈服点，具有很好的刚性。
可以理解的是，对本领域普通技术人员来说，可以根据本发明的技术方案及其发明构思加以等同替换或改变，而所有这些改变或替换都应属于本发明所附的权利要求的保护范围。

Claims (7)

  1. 一种氰乙基纤维素的制备方法，其特征在于：所述制备方法包括以下步骤：
    步骤一、对纤维素进行碱化，称取纤维素，加入异丙醇与乙醇的混合液，再加入不同浓度的氢氧化钠溶液，并进行搅拌；
    步骤二、对纤维素进行氰乙基化，将步骤一的混合物进行抽滤压榨，加入丙烯腈和二氯甲烷的混合液，并进行搅拌，然后分阶段升温、反应，醚化结束后用相应量的乙酸终止反应；
    步骤三、将步骤二获得的混合物进行沉析，用乙醇或去离子水洗涤并干燥。
  2. 如权利要求1所述的氰乙基纤维素的制备方法，其特征在于：所述步骤一中的异丙醇与乙醇的混合液中异丙醇与乙醇溶液比例为3∶7。
  3. 如权利要求1或2所述的氰乙基纤维素的制备方法，其特征在于：所述步骤一中的搅拌是在室温下进行，搅拌2小时，进行溶解、碱化。
  4. 如权利要求1所述的氰乙基纤维素的制备方法，其特征在于：所述步骤二中将混合物取出并用抽滤装置压榨，之后捏碎分散成小颗粒物。
  5. 如权利要求1或4所述的氰乙基纤维素的制备方法，其特征在于：所述步骤二中搅拌在室温下进行，分阶段升温至50℃，反应两个小时。
  6. 如权利要求1所述的氰乙基纤维素的制备方法，其特征在于：所述步骤三中将混合物缓慢倒入体积浓度75％乙醇中进行沉析。
  7. 如权利要求1或6所述的氰乙基纤维素的制备方法，其特征在于：所述步骤三中用乙醇或去离子水洗涤三次，并在60℃下干燥。
PCT/CN2017/079429 2017-04-05 2017-04-05 氰乙基纤维素的制备方法 WO2018184146A1 (zh)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU481622A1 (ru) * 1973-11-16 1975-08-25 Предприятие П/Я А-7594 Способ получени цианэтилового эфира целлюлозы
WO1998021246A1 (de) * 1996-11-08 1998-05-22 Rhodia Acetow Ag Verfahren zur herstellung von cellulosederivaten
CN1207104A (zh) * 1996-11-08 1999-02-03 罗迪阿阿克土公司 纤维素衍生物的制备方法

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU481622A1 (ru) * 1973-11-16 1975-08-25 Предприятие П/Я А-7594 Способ получени цианэтилового эфира целлюлозы
WO1998021246A1 (de) * 1996-11-08 1998-05-22 Rhodia Acetow Ag Verfahren zur herstellung von cellulosederivaten
CN1207104A (zh) * 1996-11-08 1999-02-03 罗迪阿阿克土公司 纤维素衍生物的制备方法

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