生产文化用纸添加阳离子淀粉效果好

国内生产一般文化用纸多以草类纤维为主要原料,草浆自身特点是细小纤维含量多、沪水性差、强度较低,为了弥补这些不足,添加阳离子淀粉,可与带阴电荷的纤维及填料直接吸附生成电化学键,提高纸张强度,增加纤维及填料保留率,提高沪水速度,降低纸浆     

阳离子淀粉的制备及其在造纸中的应用

一、前言阳离子淀粉是一类经过化学变性的淀粉衍生物，通过变性而使淀粉带有阳离子基团，从而具有正电性，使淀粉性质大大改变，如糊化温度大大降低，糊液稳定性增加等，克服了原淀粉的凝沉作用，使用效率大大提高。在造纸工业中，由于纤维、填料、松香胶都带有负电荷，阳离子淀粉能与这些物质发生相互吸附，其自身留着率高；淀粉自身羟基和阳离子性使纤维之间、纤维与填料之间接触面积增大，结合力增加，从而起增强作用；阳离子淀粉可中和浆料中带的负电荷，使浆料中微粒表面和Zeta电位接近等电点，从而使填料和细小纤维的留着率达到最大…     

浆浓及助留助滤剂对桉木浆纤维悬浮液屈服应力的影响

纸浆纤维悬浮液的屈服应力（τy）是纸浆流体力学的关键流变参数。研究了桉木漂白硫酸盐浆（BKP）的浆浓（Cm）以及分别添加阳离子聚丙烯酰胺（CPAM）和阳离子淀粉对其纤维悬浮液屈服应力的影响。结果表明,在稳态剪切条件下,桉木BKP纤维悬浮液屈服应力随浆浓的升高而迅速增大,两者符合指数关系,即τy=aCbm（a=3.20,b=2.62）;添加CPAM或阳离子淀粉后,两者仍满足该指数关系,但添加CPAM后,a值减小、b值增大,而添加阳离子淀粉后,a和b值均在原来的基础上上下浮动。浆浓一定的桉木BKP,其屈服应力随CPAM添加量的增加,先增大后减小,但仍大于不添加CPAM桉木BKP纤维悬浮液的屈服应力;当浆浓为4.0%、添加约0.6%（相对于绝干浆质量,下同）的CPAM时,其屈服应力增幅最多,达30%;随着阳离子淀粉添加量的增加,屈服应力先增大后减小,当添加约为2.5%的阳离子淀粉、浆浓4.0%时,桉木BKP纤维悬浮液屈服应力下降最多,降低了约25.4%。     

造纸法再造烟叶浆料的湿部化学特性研究

试验了不同烟草浆浓及细小纤维对湿部化学的影响,研究了助剂CP、阳离子淀粉、瓜尔胶、硫酸铝等对烟草浆湿部化学电荷特性的作用。结果表明:浆浓、细小纤维含量会规律性改变Zeta电位;助剂CP、DM改变烟草浆的Zeta电位,呈抛物线趋势,均存在极大值;阳离子淀粉对Zeta电位影响明显,但用量过大出现断纸;瓜尔胶用量由0增加到0.18%时,Zeta电位提高35.12%;硫酸铝用量从0增大到0.014%时,Zeta电位提高2.8%,作用不明显。     

淀粉在涂布白卡纸中的应用

在涂布白卡纸生产过程中,淀粉按不同的用途可分为浆内添加阳离子淀粉、抄纸网部喷淋淀粉、烘干部纸板表面施胶淀粉、涂料中作为辅助胶粘剂、保水剂的改性淀粉。1 浆内添加阳离子淀粉浆内添加阳离子淀粉是中性施胶剂ASA或AKD和填料CaCO3的配套助剂。在中性施胶系统中,阳离子淀粉通过形成氢键的能力及其较高的分子质量来提高纤维间结合的能力。另外,阳离子淀粉具有阳电荷、密度强、取代度（DS）较高的特点（取代度＝含氮量／系数K）,它有助于胶料粒子通过静电留着在纤维上,减少细小纤维和碱性填料的流失。阳离子能增进纤维间的结合…     

填料对二次胶粘物沉积的影响

以丙烯酸树脂作为废纸回用过程中产生的二次胶粘物的模型物,对作为填料的滑石粉和轻质碳酸钙对二次胶粘物的吸附以及沉积性能的影响进行了研究.研究结果表明,填料级的滑石粉和轻质碳酸钙对二次胶粘物具有相近的吸附能力.在没有其他可造成二次胶粘物失稳的物质加入时,滑石粉和轻钙对二次胶粘物的吸附会导致沉积的产生;与不加入填料相比,在阳离子聚丙烯酰胺和阳离子淀粉加入量较低的情况下,填料的加入会导致沉积量的明显增加;而在阳离子聚合物加入量较大的情况下,阳离子聚合物与二次胶粘物以及填料形成的絮聚物在纤维上的有效吸附使这种影响减小.     

细小纤维与CPAM共絮凝体的性质

采用针叶木浆板为原料制备细小纤维,阔叶木浆板为原料制备标准纤维.加入不同量的细小纤维与填料共絮凝,改变它们的添加顺序,利用CPAM研究其共絮聚体的留着和对纸浆滤水性能的影响,结果表明：在阳离子聚丙烯酰胺作用下,填料和细小纤维的添加顺序影响浆料的滤水性和填料的留着,先加填料比先加细小纤维的浆料滤水性好,填料留着也高.     

在高速新闻纸机上使用阳离子淀粉提高新闻纸表面强度的实践

对阳离子淀粉在高速新闻纸机上用来提高新闻纸表面强度进行研究。结果表明：添加阳离子淀粉能明显改善新闻纸的表面强度和抗张强度;纸张的撕裂度随着阳离子淀粉用量的增加呈现先上升后下降的趋势;阳离子淀粉能显著提高浆料的滤水性能以及保留率。     

阳离子淀粉—在纸机湿部的作用

阳离子淀粉带有正电荷,与成浆悬浮液中的纤维和填料的负电荷相互作用,维持湿部电荷的综合平衡。凝聚与分散之间的平衡影响匀度、留着、滤水和产量。原淀粉能与阳离子化剂进行不同程度的反应。因而适于特定的湿部,改善匀度和留着。当用于施胶压榨时,阳离子淀粉提高填料的含量,降低流失和提高产量;当添加至成浆时,损纸障害较少。     

羧甲基壳聚糖/硫酸铝改性滑石粉在高加填纸中的应用

采用羧甲基壳聚糖和硫酸铝对造纸填料滑石粉进行表面包覆改性,对改性填料的应用进行了研究。结果表明,在羧甲基壳聚糖用量一定时,沉淀剂硫酸铝的用量对填料的改性过程和改性填料的应用性能有较大影响。当硫酸铝用量为6%时,与未改性加填相比,在灰分提高27.2%的前提下,加填纸张抗张指数仍可提高22.5%,同时加填纸张的白度和不透明度均较好。SEM观察表明,填料形态发生变化,颗粒粒径变大,形成了填料粒子的聚集体;加填纸张的SEM观察表明,滑石粉经改性后,能和纸张纤维形成更有效的吸附,提高填料和纤维之间的结合力,进而改善纸张的强度和纸料留着性能。     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Influence des ions sur le pouvoir hydratant de l'ure e: e tude sur peau de porc ex vivo

This study deals with the influence of ions (NaCl and MgSO4) in a W/O emulsion containing 10% urea. Moisturization kinetics are assessed by corneometry on pig skin ex vivo. The formula's influence on urea penetration is measured by infrared spectrometry with an ATR device and the stripping method. Corneometry and spectroscopy were chosen to record simultaneously the hydratation levels and urea localization into superficial cell layers. Urea crystallization after evaporation of emulsions and aqueous solutions is described. Results show that urea does not hydrate nor penetrate when applied to the skin through an aqueous gel. In a W/O emulsion, sodium chloride increases the ability of urea to moisturize without improving penetration. In vitro urea crystallization is disturbed by sodium chloride or magnesium sulphate for solutions and emulsions. This stabilization by ions is correlated with good moisturization values. The stabilization of urea in the solute state provided by ions increases its water epidermal binding capacity without enhancing penetration.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.