食品包装用塑料编织袋的典型项目检测与分析

食品包装用塑料编织袋的安全性对食品安全的影响很重要。从国家标准、生产许可证要求及其他质量关注热点,重点分析2种塑料编织袋的拉伸负荷、跌落、剥离力、蒸发残渣及增塑剂项目,研究了食品包装用塑料编织袋中蒸发残渣在4%乙酸(体积分数)食品模拟液中的迁移规律,对蒸发残渣成分进行定性分析,确定了编织袋产品质量问题产生的原因,并提出了提高产品质量的应对措施,建议标准的修订,建立编织袋产品的质量安全评价体系,发展绿色包装。     

应建立化肥编织袋回收制度

编辑同志: 目前,由于化肥编织袋原料聚丙烯紧缺,市场上化肥编织袋成了抢手货,不少厂常常为买不到化肥编织袋而忧虑。可是,在化肥销售的农村市场上却出现了另一种现状。最近,笔者从几位乡供销员那里获悉,农民家中散失着大量的化肥编织袋,他们想卖却又找不到门路。我认为解决这一问题的根本途径是建立编织袋回收制度,将当年散失在农民家中的化肥编织袋收上来,重新复用。这样不仅能缓和化肥编织袋紧缺的矛盾,而且也有利于增收节     

重载膜热合机尿素包装线的应用

四川美丰化工股份有限公司化肥分公司尿素车间原来采用传统的塑料编织袋缝包机缝合包装，由于尿素生产规模的不断扩大和产品市场的不断拓展，塑料编织袋包装的弊端日益显现出来。为了便于产品贮存和提高包装的外在形象，公司新增了重载膜热合机包装线，将原缝合包装改为重载膜塑料袋包装，采用热合机热合封口。现将重载膜热合机包装线在安装和使用过程中出现的问题及改进措施进行小结。     

HDPE塑料编织复合包装袋的生产工艺

<正> 最近几年我国从国外引进近百条塑料编织袋生产线,生产能力猛增,塑编袋应用领域不断扩大。目前广泛用于包装化肥、水泥、食糖、粮食、各种粉状、颗粒状化工产品及中草药等。对改善上述产品的包装,降低破损,起到了积极的作用。但是由于我国用于生产编织袋的PP原料的生产量有限,满足不了加工能力的增长需     

六氢哒嗪中的灼烧残渣去除方法研究

六氢哒嗪制备过程中使用大量无机盐,直接导致了最终产品的灼烧残渣含量远远超标,本文研究了洗涤去除该无机盐的方法,通过该方法,可以使灼烧残渣含量小于0．01％。     

一种塑料贴膜编织袋

正本实用新型涉及一种塑料贴膜编织袋,属于编织袋技术领域。解决了现有技术中编织袋不可循环使用、易滋生细菌、易受潮的技术问题。本实用新型的编织袋,由塑料贴膜、双面粘结层、不粘胶层、袋体、抗菌层、拉链、可变形框架、防水层和阻隔层组成;袋体为上表面设有开口的中空方体,袋体的材料为塑料编织袋;可变形框架为方体框架,形状与袋体配合,能够恰好放置在袋体内,可变形框     

环保型编织袋油墨在武汉开发成功

近期,一种环保型编织袋油墨由武汉现代工业技术研究院研制成功。编织袋油墨是专供塑料编织袋上印刷图案、商标、文字的一种油墨,而现在市场     

聚乙烯树脂中灼烧残渣测量不确定度的评定

按照2017年3月1日新实施的GB 31604.6-2016《食品安全国家标准食品接触材料及制品树脂中灼烧残渣的测定》的分析方法处理分析样品,在此基础上建立灼烧残渣不确定度的数学模型。通过分析测定过程不确定度的各种来源,计算各不确定度分量。     

化工标准化动态

近期实施或即将实施的塑料系列标准
　　1)GB/T 8946—2013《塑料编织袋通用技术要求》。规定了塑料编织袋的术语和定义、分类、型号、规格、命名、标识、材料和半成品、要求、试验方法、检验规则、标志、包装、运输和贮存。适用于以聚丙烯、聚乙烯和聚酯等树脂为主要原料,经挤出、拉伸成扁丝,编织、制袋而成的塑料编织袋。     

硫酸渣中全铁分析的样品分解比对与探讨

用三种分解方式:直接酸溶法、酸溶残渣回收、灼烧后酸溶法对硫酸渣样品的检测结果进行了比对与探讨,结果显示极少数硫酸渣样品,三种分解方式的检测结果一致,多数难溶硫酸渣样品酸溶法偏低,灼烧后酸溶法与酸溶残渣回收有好的一致性,灼烧后酸溶法简单快速。     

一种LOVA发射药燃烧残渣现象分析

针对点火模拟装置中某种LOVA发射药燃烧结束留有残渣的现象,将自制样品在常温和常压下进行环境燃烧试验、中止燃烧试验及SEM观察.归纳出残渣产生的原因,分析了LOVA发射药的燃烧规律和燃烧特性.结果表明,配方中RDX组分与含能黏结剂BAMO/AMMO聚合物体系的燃烧不同步性、以及该类发射药氧含量低是造成LOVA发射药燃烧...     

Mass-transfer studies at rotating cylinder electrodes with turbulence promoters

Mass transfer was studied at a rotating cylinder electrode with different turbulence promoters using the reduction of ferricyanide as a test reaction. Four types of turbulence promoters were examined: expanded plastic meshes, Teflon structures, a plastic woven mesh and a plastic perforated net, which were rotated together with the electrode. The best performance was obtained for the Teflon structures at low rotation speeds and for the plastic woven mesh at high rotation speeds. The effect of both the length and the number of sheets of the turbulence promoters as well as the use of static promoters were also analysed. Comparisons of mass-transfer performance of turbulence promoters are made with other three-dimensional structures. The mass-transfer enhancement factor related to a smooth rotating cylinder electrode is twice as large.     

聚丙烯粉料直接涂覆法生产复合塑料编织袋技术探讨

介绍了聚丙烯粉料直接涂覆法生产复合塑料编织袋的工艺技术，讨论了原料和助剂对涂覆质量和生产过程的影响。结果表明：通过选择合适的混配料配方和适当的工艺条件，可以实现复合塑料编织袋的稳定生产，产品的涂覆质量符合国标要求。     

HIPS/OMMT复合材料炭渣结构对阻燃性能的影响

采用熔融插层法制备了高抗冲聚苯乙烯/有机蒙脱土(HIPS/OMMT)和高抗冲聚苯乙烯/蒙脱土(HIPS/MMT)复合材料,并通过锥形量热仪评价了复合材料的阻燃性能;采用数码相机、扫描电镜(SEM)观察了燃烧残余物结构,对残余物结构进行了热重(TGA)分析。结果表明:OMMT的加入显著提高了复合材料以热释放速率表征的阻燃性能,而HIPS/MMT复合材料的阻燃性能提高不明显;HIPS/OMMT纳米复合材料燃烧热释放速率峰值时形成了皮窝复合炭渣结构,皮层组分主要为硅酸盐及部分难分解的碳质物质,热稳定性较高,窝层起膨胀炭层的作用,二者共同起阻燃作用。     

Combustion of NaN3 Based Energetic Pyrolants

The burning rate of pyrolants composed of NaN₃ and metal oxides was investigated in order to gain information on their combustion characteristics. The metal oxides mixed with NaN₃ were Fe₂O₃, CoO, Co₃O₄, and CuO. The effect of the addition of whiskers and fibers was also examined. The test results indicated that the burning rate was highly dependent on the type of ingredients and the mixture ratio of the ingredients. The pyrolant composed of NaN₃/CuO (61/39) appeared with the highest burning rate, 50 mm/s at 7 MPa, throughout the burning rate experiments. The residue of the combustion products of each sample was examined to evaluate the effectiveness of the gas generation.     

用锥形量热仪评价异氰酸酯指数对硬质聚氨酯泡沫塑料阻燃性能的影响

利用锥形量热仪研究了异氰酸酯指数对硬质聚氨酯泡沫塑料燃烧性能的影响,结果表明:随着硬质聚氨酯泡沫塑料异氰酸酯指数的提高,材料的热释放、烟释放及有毒气体CO的释放都明显降低。     

纸塑复合材料在管材中的应用

介绍了废旧纸塑编织袋与PP复合材料在生产管材中的应用情况,探讨了纸塑复合材料的配方、纸塑编织袋的处理、工艺及制备方法。结果表明:经偶联剂处理过的纸塑复合材料,在纸塑复合之间形成了较高强度的界面层,增强了管材强度,提高了管材的力学性能。     

Influence of Particle Size on the Combustion of CL‐20/HTPB Propellants

The effect of nitramine particle size on the combustion behavior of inert binder based propellants has been extensively studied for RDX and HMX, but not CL‐20. Although materials such as RDX and HMX are useful for particular combustion applications, CL‐20 has a greater potential to improve the oxygen balance and energy density of a propellant. The current work investigates the effect of CL‐20 particle size on the combustion of CL‐20/HTPB propellants down to submicrometer sizes. An influence of particle size on the burning rate and combustion mechanism is reported. The 30 micrometer formulation burning rate data showed evidence of convective burning specifically at higher pressures, but the pressure dependence was comparable to neat CL‐20 at pressures below 8 MPa. A change in the combustion mechanism of the submicrometer formulation as a function of pressure was determined to be a result of the interaction of the propellant flame and the combustion residue. Data suggested that at low pressures diffusion in terms of active cooling was dominant for the submicrometer formulation. Higher pressure data for both the submicrometer and 3 micrometer formulations suggest the degree of active cooling is decreased as the burning rate pressure exponent is near 0.5 for both propellants. The indirect evidence for the presence of a melt layer for CL‐20 propellants is discussed.     

生料细度对硅酸盐水泥熟料烧成的影响

研究了在高饱和比、高硅率的体系内,生料细度及对应细度筛余物中f-SiO2含量对硅酸盐水泥熟料烧成的影响。结果表明:在同一率值范围内,生料越细,熟料中w(f-CaO)越低,易烧性越好;生料中f-SiO2含量越高,易烧性越差,熟料中f-CaO含量越高;当0.2mm方孔筛筛余中w(f-SiO2)含量低于0.5%时,物料的颗粒尺寸愈小,反应界面和扩散截面增加,反应产物层厚度减少,熟料的烧结过程容易进行,熟料的亚微观结构中各矿物分布均匀,晶体大小适中;当0.2mm方孔筛筛余中w(f-CaO)高于0.5%时,各矿物分布不均匀,形成单一B矿区域,A矿形成数量明显减少。     

Oxidation of ammonia on woven and knitted platinoid gauzes

The results from pilot tests of catalytic systems equipped with 7–12 woven or 5–14 knitted platinoid gauzes in the oxidation of ammonia are considered. OAO Yekaterinburg Non-Ferrous Metal Processing Plant produces gauzes of the two types: Pt₀₉₂ 0.092-mm wire woven and Pt₀₇₆ 0.076-mm wire loosely knitted (large-mesh) gauzes. Both types of gauzes are made of PdRdRu 15-3.5-0.5 alloy (referred to as alloy no. 5) and have the following elemental composition: Pt, 81%; Pd, 15%; Rh, 3.5%; Ru, 0.5% (STO (Branch Standard) 00195200-013-2007 and STO (Branch Standard) 00195200-014-2007). The third type is 0.076-mm tightly knitted (small-mesh) gauzes (Uncore, Germany), which differ from the Russian knitted Pt₀₇₆ gauze by their greater mass and external surface area per unit reactor cross section. The effect of the mass, external surface area, and free volume of woven and knitted platinoid gauzes on the yield of nitrogen oxide is studied in this work, and the residual concentration of ammonia downstream of a stack of gauzes is determined in dependence on their number. The efficiency of the unit surface of knitted gauzes depends on the influence exerted by transfer phenomena and the direct homogeneous ammonia reduction of nitrogen oxide in the free volume of a platinoid catalyst stack. Loosely-knitted Pt₀₇₆ gauzes are less efficient than woven Pt₀₉₂ gauzes within a ≥91.5% range of nitrogen oxide yields. Tightly knitted gauzes are suitable for use within a ≤94.5% range of nitrogen oxide yields. Yields equivalent to those obtained on woven gauzes cannot be attained on tightly knitted gauzes even after their external surface area is enlarged considerably. Maximum nitrogen oxide yields (≈95%) are attained on Pt₀₉₂ woven gauzes. From the results of our tests of loosely and tightly knitted platinoid gauzes, it follows that the latter (with less free volume in a stack) are preferable for use. The free volume of gauzes and the fraction of ammonia for nontargeted conversion can be minimized by placing a smaller number of loosely knitted platinoid gauzes on a regular honeycomb block catalyst or packing bed.