交联剂在室温固化双组分水性涂料中的应用

用多异氰酸酯型、氮丙啶型和环氧基型三种室温固化交联剂分别固化丙烯酸聚氨酯分散体水性涂料,测定并比较了交联涂膜的性能。结果发现,环氧型交联剂固化的产物综合性能最好,主要表现在涂膜硬度、附着力、耐水性、耐溶剂性、耐污渍性和耐烫性上比未交联涂料和其他两种交联剂固化的涂料要好得多。此外,配漆后的适用期很长,施工方便程度类似于单组分涂料。     

Barrier coats versus inert atmospheres. The elimination of oxygen inhibition in free-radical polymerizations

The polymerization of UV-curable coatings that react by a free-radical mechanism is subject to oxygen inhibition which can be avoided by utilizing an inert atmosphere. We demonstrate that wax barrier coats used to prevent evaporation of volatile reactive monomers are equally effective in preventing oxygen inhibition. No quantitative difference is found between the degree and rate of polymerization in an inert atmosphere or with a wax barrier coating. However, when used above a given ceiling temperature, the wax barrier allows oxygen diffusion which inhibits cure.     

RANDOM EXPERIMENTS ON ENAMEL ADHERENCE*

The results of various experiments dealing with the behavior of ground-coat enamels are given. Hydrogen causes metallic nickel or iron to separate from regular molten ground coats, while the gases evolved from sheet iron cause metallic copper to form from molten copper-bearing glasses and metallic iron to form from regular molten ground coats. Ground coats have only a slight volatilization loss at 1600°F. Because CuO decomposes when heated in absence of oxygen or with iron or FeO, the various experiments performed suggest that glass solutions of CuO are oxidizing and are reduced by such reducing agents as H₂, CO, FeO, CoO, NiO, MnO, and Fe.     

Hybrid carbon nanotubes/graphene modified acrylic coats

Water-borne one-component acrylic coating compositions and coats modified with carbon nanotubes (CNT), graphene (GN), as well as hybrid carbon nanofillers (CNT/GN mixtures) have been prepared and evaluated. These coating materials were successfully formulated on a basis of commercial components, i.e. acrylic resin aqueous dispersion, CNT and/or GN and auxiliary agents. Influence of a kind and ratio of incorporated carbon nanofillers on the following coats properties was investigated: electrical surface resistivity, transparency, gloss, mechanical (hardness and cross-cut adhesion) and thermal properties (glass transition temperature, storage modulus and thermal stability). The presence of carbon nanostructure significantly improved electrical conductivity, hardness, storage modulus and thermal stability of the coats. Moreover, the nanofillers did not negatively influence adhesion and glass transition temperature.     

Chemorheological time‐temperature‐transformation‐viscosity diagram: Foamed EPDM rubber compound

Thermal analysis, rheometry, and kinetic modeling are used to generate a comprehensive processability diagram for thermosetting and elastomeric resins. A chemorheological “time‐temperature‐transformation‐viscosity” diagram is proposed to fully characterize curing reactions toward process' on‐line control, optimization, and material design. Differential scanning calorimetry and thermogravimetric techniques are used to measure total reaction heat, degree of vulcanization, and cure kinetics. The viscosity, as a function of temperature and cure degree, is obtained from parallel plate rheometry. The auto‐catalytic Kamal–Sourour model, including a diffusion‐control mechanism, is used to model cure kinetics, while the Castro–Macosko model serves to model the rheological behavior. Non‐linear least‐squares regression and numerical integration are used to find models' parameters and to construct the chemorheological diagram. The usefulness of the proposed methodology is illustrated in the context of an industrial‐like Ethylene Propylene Diene Termononer rubber compound that includes a chemical blowing agent. Even though the rubber formulation contains crosslinking agents, primary and secondary accelerators, promoters, activators, and processing aids, the chemorheological diagram is obtained consistently, validating the proposed methodology to any thermosetting or elastomeric resin. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43966.     

Development of a predictive model for choosing cure agents for elastomer blends

In elastomer blends with either polarity differences or unbalanced double bond concentration, cure agents have a preferential partition to one of the phases, with a tendency of having overcure in one phase and undercure in the other. To achieve proper vulcanization and improved performance in the final product, it is essential to have a correct balance between solubility and miscibility of each of the various cure agents in the elastomer blend composite. Cure agents with varying polarities and various reactivities have different crosslinking densities in the rubber compound. A homogeneous crosslinking density leads to superior mechanical properties. The method presented in this work includes a new tool based on a genetic optimization algorithm for assessing the partitioning of cure agents in different elastomers and their blends. The quantitative data allowed for a series of analyses of the solubility of the cure agents in the elastomer mixtures of different phases and was validated by correlation with their physico–chemical and mechanical properties of the resulting blend. This is an important tool for planning a cure system in rubber blends and to avoid incorrect partitioning of cure agents and consequent uneven curing of the final compound. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41929.     

Aspects of Latency in Epoxy Film Adhesives

Studies have shown that the cure of epoxy resins with urea hardeners, either alone or in conjunction with dicyandiamide, is influenced by the ability of adventitious agents, products, or by-products to volatilise from the reacting system. Although a generalised mechanism has not been identified, the phenomenological findings are important in evaluation and characterisation of adhesives and cure schedules, particularly by thermal analysis, and need to be considered in any detailed chemical study of these systems. Propenal has been identified as a significant by-product of cure under certain conditions.     

Transesterification cure for coatings: catalysis by epoxy and nucleophiles

Transesterification cure in coatings can be catalyzed by an alkoxide which is formed during bake by the combination of an epoxide with a nucleophile. Support for transesterification cure in the presence of epoxides and nucleophiles has been provided by FTIR evolved gas analysis (EGA/FTIR) and thermal gravimetric analysis (TGA). Effective nucleophiles include tertiary amines, certain inorganic nucleophiles like cyanide, hydroxide and azide, and quaternary ammonium salts. Quaternary ammonium carboxylates are particularly effective nucleophile sources for this cure chemistry, especially those that have better thermal stability. EGA/FTIR was used to demonstrate differences in the thermal stability of quaternary ammonium salts, and these differences were correlated with differences in cure at higher bake temperatures. Transesterification cure of hydroxyl functional acrylics can provide greatly improved impact resistance if the acrylics are blended with polyesters. Dynamic mechanical analysis (DMA) has shown differences between acrylic and acrylic-polyester blends which may help to explain the differences in impact resistance.     

Process cure monitoring of unsaturated polyester resins,vinyl ester resins,and gel coats by Raman spectroscopy

The curing process of unsaturated polyester resins, vinyl ester resins, and gel coats was studied by using a process Raman spectrometer, equipped with a remote fiber‐optic probe. The resins were cured and Raman spectra were recorded during the curing reaction. The spectral changes were identified and, from the intensities, the cure process could be monitored. Gel times given by the resin suppliers correlated well with the Raman results. It could also be seen that the curing process continues for a long time, up to several weeks. Postcuring will finally complete the curing process. White and lightly colored gel coats could easily be monitored by Raman spectroscopy, but fluorescent problems were encountered with heavily colored pigments. The curing of laminates containing 50–70 wt % glass fiber mat could also be followed by Raman spectroscopy. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1285–1292, 2004     

抗硫化返原剂在纯天然橡胶复合体系中的应用研究

研究了抗硫化返原剂Perkalink900（简称PK900）、AK-73对纯天然橡胶复合体系的抗硫化返原性能、物理机械性能及生热性能的影响，结果表明：无论是在普通硫化体系还是在半有效硫化体系中，加入一定量PK900、AK-73后，胶料的抗硫化返原性能均得到提高。就这2种抗硫化返原剂而言，在不同的硫化体系中，在不同的温度下，表现的结果有所不同：在半有效硫化体系中，高温过硫情况下，PK900的作用更加明显，同时，加入一定量的抗硫化返原剂后，胶料的定负荷压缩生热性能得到一定程度的改善。     

ABS塑料用环氧树脂粘合剂的研究

经迈克尔加成反应,用丙烯腈制作了一系列改性多元胺固化剂,将其与双酚A型环氧树脂配合,用于粘接ABS塑料。研究结果显示,丙烯腈改性固化剂有助于改善环氧树脂胶对ABS塑料的粘接强度,随着固化剂中氰基含量从0 mmol/g增加到0．949 mmol/g,丙烯腈改性环氧树脂体系(acrylonitrile-modified epoxy resin system,AMEPS)对ABS塑料的粘接强度增长约32%,而玻璃化温度降低约9%,与此同时,改性环氧树脂的吸酸率呈先降后升趋势。     

Synthesis and evaluation of functional polymeric additives with urethane linkage as dispersing agents for preparation of pigment concentrates with high solid loading, low-VOC content, and usefulness for industrial coatings

A synthetic strategy based on precursor and prepolymer approaches has been adopted for preparing the functional polymeric agents with urethane linkage and functional groups such as –CONH–, –COOH, –NH–, C–N, –COOR and C–Cl, that can interact with the pigment surfaces. The agents were tested for their dispersion capacity. High pigment-loaded (as high as 64%) and solvent-free stainers with potential applications in low-VOC paints were successfully prepared. The stainers were mixed with two commercial binder resins—namely epoxy base white and polyurethane metal coat binder resins—to get first paints and their coats on various substrates such as standard glaze paper, tin and mild steel panels. The paint-specific properties, viz. percentage opacity, color strength, solvent resistance, adhesion, scratch hardness and salt spray resistance, were measured to adjudge the suitability of high pigment-loaded coats in industrial applications. The properties measured in general showed improvement in spite of the increase in the pigment loading. The paint coats resisted not only the xylene, petrol, and lubricating oil attack but also humidity and salt spray (up to 1000 h of exposure).     

The phase mixing studies on moisture cured polyurethane-ureas during cure

Moisture cured polyurethane-urea (MCPU) is one of the industrially important polymers that shows good thermal, mechanical and weathering properties and is widely used in the reactive hot melt adhesives and coatings. Structural variation of the building blocks, i.e. soft, hard segment and chain extender structure on the phase mixing characteristics during cure in polyether based moisture-cured polyurethanes (MCPUs) has been investigated. Variations in the soft segment structure like polyethylene glycol (PEG), polypropylene glycol (PPG) and polytetramethylene glycol (PTMG) and hard segment like toluene diisocyanate (TDI) or isophorone diisocyanate (IPDI) were made. The effect of isocyanate content (NCO:OH ratio 1.6:1 and 2:1) as well as various aliphatic diol and aromatic diamine chain extenders were also compared. The phase mixing phenomenon during network growth was evaluated by differential scanning calorimetry (DSC) and a correlation was drawn for the degree of cure with the phase mixing property. The change in modulus and thermal stability with the cure advancement were measured by dynamic mechanical and thermal analysis (DMTA) and thermogravimetric analysis (TGA). A correlation was made for the soft, hard segment and chain extender structure to the phase mixing phenomenon during cure. The rate of phase mixing was found to be dependent on the subtle variations in molecular architecture.     

Flexible clear coats—Effect of curing conditions

The effect of curing at different conditions was investigated for flexible model clear coat films for coil coating applications. Based on a commercial polyester binder two formulations with isocyanate based crosslinking agents (hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI)) were prepared. The clear coats were baked at laboratory (145 °C) and industrial processing (300 °C) conditions. While for high temperature curing the baking time was kept constant at 30 s, the curing time at 145 °C, which is above the deblocking temperature of the crosslinking agents, was varied from 10 to 90 min. The clear coat films were characterized as to their thermomechanical and mechanical properties by dynamic mechanical analysis (DMA) and by tensile testing. Regarding DMA loading in tensile and penetration mode was performed.     

复合防腐涂料在中—阿化肥公司的应用

通过对本厂环境条件和带涂层金属件的腐蚀原因分析,确定了中－阿化肥有限公司金属设施采用两道ＥＰ－６７玻璃鳞片涂料和三道ＪＧＨ氯磺化聚乙烯涂料的复合涂层进行防腐蚀,获得了良好的应用效果。     

Biorenewable ROMP-based thermosetting copolymers from functionalized castor oil derivative with various cross-linking agents

A new norbornenyl-functionalized castor oil alcohol (NCA) was synthesized and ring-opening metathesis copolymerized separately with two norbornene-based cross-linking agents: dicyclopentadiene (DCPD) and a bifunctional norbornene crosslinker (CL). Isothermal differential scanning calorimetry (DSC) was used to examine the cure behavior of NCA/DCPD and NCA/CL resins, through which a reasonable cure schedule was determined. The glass transition temperature (T_g) and storage modulus (E′), characterized by dynamic mechanical analysis (DMA), increased significantly in both copolymer systems with the addition of cross-linking agents. Cross-link density of the two systems was evaluated using a modified empirical equation from the kinetic theory of rubber elasticity. Differences in tensile stress-strain behavior and thermal stability between polymerized NCA/DCPD and NCA/CL were correlated to the structural rigidity and cross-linking density resulting from the cross-linking agents.     

Development of waterborne UV-A curable clear coat for car refinishes

The development of a waterborne UV-A curable clear coat for car refinish application is described. The clear coat formulations are based on specially developed acryloyl or maleimide functional polyurethane dispersions. The functional PUR dispersions are characterized by a relatively low molecular weight, a high CC functionality and an optimized amount of poly(ethylene oxide). These characteristics are necessary for obtaining optimal film formation which results in good appearance and other film properties. It was found that poly(ethylene oxide) had a positive effect on surface cure when irradiated with UV-A light (less influence of oxygen inhibition). The synthesis of PUR dispersions and their performance in clear coats are described, including several aspects on film formation (conversion of CC, AFM measurements) and film properties (durability, physical and chemical properties).     

Kurzgefaßte Darstellung eines Analysengangs für Zahnpasten

Outline for the Course of the Analysis of Toothpastes An outline of the analysis of toothpastes is given whereby only a digest on tbe suitable analytical methods without details of the working instructions is described- Besides the possibilities for the detection and determination of the basis components like polishing agents, moisturizing agents, detergents, thickening agents, flavors, sweetening agents, preservatives and dyes also methods for the analyses of special ingredients used in toothpastes are treated, for instance fluorine compounds, antimicrobial agents, plaque inhibiting agents, antiphlogistic and hyperaemic substances and gum desensibilising agents.     

硬度法研究浇注聚氨酯弹性体的固化动力学

用硬度测量法研究了两种浇注聚氨酯弹性体的固化反应动力学，线性回归计算了固化反应级数，速率常数，最终硬度及反应活化能，说明了测定和处理方法。结果表明，反应级数随固化反应温度的增高而增大，产物最终硬度与固化温度有关，不同的固化体系反应活化能有很大的差别。由此可见，这类浇注聚氨酯弹性体的固化反应可能是若干复杂反应的综合过程。     

Cure Characteristics and Mechanical Properties of Short Nylon-6 Fiber Neoprene Rubber Composite Containing Epoxy Resin as Bonding Agent

ABSTRACT

Cure characteristics and mechanical properties of the short nylon fiber reinforced neoprene rubber with and without epoxy bonding agent at various fiber loadings were studied. The fiber loading was varied from 0 to 30 phr and the resin content was in the range 0 to 5 phr. Minimum torque and cure time were increased in the presence of resin. Mechanical properties like tensile strength and abrasion resistance showed an increase with resin concentration. It was found that epoxy based bonding agents enhanced the properties of short nylon fiber reinforced neoprene rubber.