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Cross-linked polyethylene special material for rotational molding
CN1523052A
China
Description
translated from Chinese
技术领域Technical field
本发明涉及一种滚塑用交联聚乙烯专用料。The invention relates to a special cross-linked polyethylene material for rotational molding.
背景技术 Background technique
滚塑是成型大中型制品的方法之一，此工艺在四十年代起源于美国，由于各种原因发展较慢，仅限于少数塑料制品的加工。近年来由于塑料及其粉末化的发展和塑料应用领域的逐步扩大，以及这种工艺的优越性，使其正在得到飞速的发展。目前国外的各类滚塑聚乙烯材料的比例大致为：线性低密度聚乙烯(LLDPE)为65％，交联聚乙烯(XHDPE)为20％，高密度聚乙烯(HDPE)10％，低密度聚乙烯(LDPE)为5％。本世纪70年代末期，线性低密度聚乙烯(LLDPE)开始步入滚塑成型领域。线型聚乙烯本身具有特别适宜于滚塑成型的特点：1、滚塑成型性好，成型周期较短；2、耐应力开裂性好；3、抗冲击性能好；4、刚性好；5、线性聚乙烯滚塑用粉料容易制得。由于LLDPE在滚塑成型加工过程及其制品上的种种优点，它已被人们认为是滚塑成型领域中富有良好发展前景的一种塑料。现在，LLDPE在滚塑中的应用已十分可观，据资料介绍，LLDPE滚塑制品已占美国全部聚乙烯滚塑制品的65％，目前已有90％的传统的高密度聚乙烯转向LLDPE。但LLDPE仍存在加工性不好、耐热蠕变性、抗低温冲击性、耐溶胀性能等方面的缺陷，这无疑限制了LLDPE的应用范围。Rotational molding is one of the methods of forming large and medium-sized products. This process originated in the United States in the 1940s. Due to various reasons, it has developed slowly and is limited to the processing of a few plastic products. In recent years, due to the development of plastics and their powdering, the gradual expansion of the application field of plastics, and the superiority of this process, it is developing rapidly. At present, the proportion of various types of rotationally molded polyethylene materials in foreign countries is roughly: 65% for linear low-density polyethylene (LLDPE), 20% for cross-linked polyethylene (XHDPE), 10% for high-density polyethylene (HDPE), and 10% for low-density polyethylene (LDPE). Polyethylene (LDPE) is 5%. In the late 1970s, linear low-density polyethylene (LLDPE) began to enter the field of rotational molding. Linear polyethylene itself has the characteristics that are particularly suitable for rotational molding: 1. Good rotational molding performance and short molding cycle; 2. Good stress crack resistance; 3. Good impact resistance; 4. Good rigidity; 5. Linear polyethylene rotomoulding powder is easy to obtain. Due to the various advantages of LLDPE in the rotational molding process and its products, it has been considered as a plastic with good development prospects in the rotational molding field. Now, the application of LLDPE in rotomolding has been very impressive. According to the information, LLDPE rotomolding products have accounted for 65% of all polyethylene rotomolding products in the United States. At present, 90% of traditional high-density polyethylene has turned to LLDPE. However, LLDPE still has defects such as poor processability, thermal creep resistance, low temperature impact resistance, and swelling resistance, which undoubtedly limit the application range of LLDPE.
发明内容Contents of invention
本发明的目的在于克服现有技术的上述缺点，提供一种滚塑成型用交联聚乙烯(LLDPE)专用料。The purpose of the present invention is to overcome the above-mentioned shortcoming of prior art, provide a kind of cross-linked polyethylene (LLDPE) special material for rotational molding.
本发明提供的滚塑成型用交联聚乙烯专用料，含有如下组份：(以线性低密度聚乙烯及低密度聚乙烯的总重量计)The cross-linked polyethylene special material for rotational molding provided by the present invention contains the following components: (based on the total weight of linear low density polyethylene and low density polyethylene)
A、线性低密度聚乙烯，70--90％；A. Linear low density polyethylene, 70--90%;
B、低密度聚乙烯，10--30％；B. Low-density polyethylene, 10--30%;
C、交联剂，0.5-5％；C, crosslinking agent, 0.5-5%;
D、抗氧剂，0.1-1％。D. Antioxidant, 0.1-1%.
本发明提供的组合物中的交联剂可为有机过氧化物，如过氧化二异丙苯(DCP)、2，5二甲基-2，5二叔丁基己烷(双2，5)、二叔丁基过氧化物等；抗氧剂可为四{-(3，5-二叔丁基-4-羟基苯基)丙酸}季戊四醇酯(抗氧剂1010)或硫代二丙酸二月桂酯(DLTP)等。The crosslinking agent in the composition provided by the invention can be organic peroxide, as dicumyl peroxide (DCP), 2,5 dimethyl-2,5 di-tert-butyl hexane (two 2,5 ), di-tert-butyl peroxide, etc.; the antioxidant can be tetrakis {-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate} pentaerythritol ester (antioxidant 1010) or thiodi Dilauryl propionate (DLTP), etc.
本发明还提供一种交联聚乙烯专用料的制备方法，该方法包括：将该专用料在开炼机或双螺杆挤出机中熔融混合，共混温度为130-170℃，即可制得该聚乙烯专用料。The present invention also provides a preparation method of special cross-linked polyethylene material, the method comprising: melting and mixing the special material in an open mill or a twin-screw extruder, and the blending temperature is 130-170°C, to produce Get the polyethylene special material.
本发明的机理在于在本发明的专用料的制备成型过程中会发生交联，从而形成网状结构。交联滚塑是一种过氧化物液相交联，通过烷基形成的C-C键达到交联，过氧化(ROOR)加热后形成活性游离基，其交联的反应式如下：The mechanism of the present invention is that cross-linking occurs during the preparation and molding process of the special material of the present invention, thereby forming a network structure. Cross-linked rotomolding is a kind of peroxide liquid-phase cross-linking. Cross-linking is achieved through the C-C bond formed by the alkyl group. After heating peroxidation (ROOR), active free radicals are formed. The cross-linking reaction formula is as follows:
ROOR-2ROROOR-2RO
交联反应在材料的熔点以上发生，交联后凝胶的产生限制了分子链的运动，使分子链不能充分、迅速而又规整地排列，所生成的晶体完善程度也较差，这样就对材料的结晶行为有较大影响，随之而来的是材料密度下降，制品具有较理想性能。两种聚乙烯共混可制取软硬适中加工性能优异的聚乙烯材料。从而适应更广泛的用途。The cross-linking reaction occurs above the melting point of the material, and the formation of gel after cross-linking restricts the movement of the molecular chains, so that the molecular chains cannot be fully, rapidly and regularly arranged, and the resulting crystals are less perfect, which is harmful to The crystallization behavior of the material has a great influence, followed by a decrease in the density of the material, and the product has more ideal properties. The blending of two kinds of polyethylene can produce polyethylene material with moderate softness and hardness and excellent processability. So as to adapt to a wider range of uses.
该专用料具有良好的流动性，在空气中能承受高温加热，滚塑成型性能良好。用该料制备的滚塑制品具有超群的抗冲击强度、耐热蠕变性能及低温韧性，良好的耐渗透性和耐化学性能等。交联聚乙烯制品的上述优良性能，使之能用于普通聚乙烯制品所不能应用的、以及不适用的许多领域，如燃油箱、化学药品用容器、垃圾箱、工业用蓄电池壳等。The special material has good fluidity, can withstand high temperature heating in the air, and has good rotational molding performance. The rotomolded products prepared with this material have superior impact strength, thermal creep resistance and low temperature toughness, good permeability resistance and chemical resistance, etc. The above-mentioned excellent properties of cross-linked polyethylene products enable them to be used in many fields where ordinary polyethylene products cannot be applied or are not applicable, such as fuel tanks, chemical containers, trash cans, and industrial battery cases.
具体实施方式 Detailed ways
实例1Example 1
配方：formula:
LLDPE 7042 70公斤LLDPE 7042 70 kg
LDPE 1F7A 30公斤LDPE 1F7A 30 kg
过氧化二异丙苯 4.5公斤Dicumyl peroxide 4.5 kg
抗氧剂1010 500克Antioxidant 1010 500g
制备：在高速混合器中将按配方配制的原料混合均匀，再在双辊开炼机上共混，共混温度为130-140℃。下片粉碎。Preparation: Mix the raw materials prepared according to the formula evenly in a high-speed mixer, and then blend on a double-roll mill, and the blending temperature is 130-140°C. The next piece was crushed.
实例2Example 2
配方：formula:
LLDPE 7042 90公斤LLDPE 7042 90 kg
LDPE 1F7A 10公斤LDPE 1F7A 10 kg
2，5二甲基-2，5二叔丁基己烷 1公斤2,5 dimethyl-2,5 di-tert-butyl hexane 1 kg
硫代二丙酸二月桂酯 900克Dilauryl Thiodipropionate 900g
制备：方法和实例1的制备方法相同。Preparation: The method is the same as the preparation method of Example 1.