NIKKA SEIKO CO.

Nozawa, Japan

NIKKA SEIKO CO.

Nozawa, Japan
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Tadano T.,NIKKA SEIKO CO. | Zhu R.,Nihon University | Muroga Y.,Nihon University | Hoshi T.,Nihon University | And 3 more authors.
Chemistry Letters | Year: 2014

The rapid agglomeration of SiO2 nanoparticles suspended in organic solvents, where the interactions between the PMMA chains and SiO2 are very weak and may be ignored, is, therefore, concluded to be "entanglement agglomeration mechanism" triggered by strong mutual entanglement effects occurring when the polymer chains come into contact, overlap, and mutually intrude each other at higher polymer concentrations, providing the driving force for particle agglomeration. © 2014 The Chemical Society of Japan.


Tadano T.,Nikka Seiko Co. | Suzuki S.,Nihon University | Zhu R.,Nihon University | Zhu R.,NIPPON CHEMI - CON Co. | And 4 more authors.
Kobunshi Ronbunshu | Year: 2014

A transparent hybrid film with hydroxypropylcellulose (HPC, Mw: 1.0 × 105) and silica particles (Si02, average diameter: 12.3 nm) was prepared by a solution cast method, based on the specific dispersion-agglomeration behavior of HPC/SiO2 nanohybrid aqueous suspensions. For the transparent suspension, with 10% of total weight of HPC and SiO2, when the weight composition of SiO2 is 0∼30wt%, free flow is maintained until the water evaporates and a high concentration is reached. Finally, a liquid crystal is formed, and the suspension becomes clouded. The transmittance of the film becomes 50∼20% (400 nm). However, when the weight composition of SiO2 is 50∼80wt%, the transparent suspension gels, after a standing time which depends on concentration. A transparent hybrid film is formed with the state maintained. The transmittance of the film becomes 90%. It is thought this gelling happens due to the forming of hydrogen bonds between hydroxyl groups in HPC and the silanol groups on the SiO2 nanoparticle surface and that the SiO2 nanoparticles are dispersed in the network uniformly, leading to transparency. © 2014, The Society of Polymer Science, Japan.


Tadano T.,NIKKA SEIKO CO. | Zhu R.,Nihon University | Muroga Y.,Nihon University | Hoshi T.,Nihon University | And 3 more authors.
Polymer Journal | Year: 2014

We examined the agglomeration behavior of a suspension of SiO2 nanoparticles with average dimensions of ∼15 nm in a solution of tetrahydrofuran and polydisperse poly(methyl methacrylate) (PMMA) with a weight-average molecular weight in the range of (0.3-31) × 104. For PMMA with a critical molecular weight (Mc) of ∼3 × 104 or larger, at which PMMA chains show effective entanglement, a critical polymer concentration (C*) was clearly observed. At C*, the dispersed SiO 2 nanoparticles came into contact with one another and rapidly agglomerated. C* increased with decreasing molecular weight. However, no clear C* was observed for PMMA (Mw: 0.3 × 104) with Mc or lower molecular weights. The molecular weight dependence of the observed C* can be explained by the depletion effect, but the lack of a clear C* for low molecular weight PMMA cannot be explained with this theory. Because C* occurs in the vicinity of the critical concentration, at which the random coils in the solution come into contact with one another and begin to overlap, the entanglement of random coils is considered to be the driving force behind nanoparticle agglomeration. However, no C* was observed because effective entanglement does not occur for PMMA with M c or lower.


Tadano T.,NIKKA SEIKO CO. | Zhu R.,Nihon University | Zhu R.,NIPPON CHEMI - CON Co. | Suzuki S.,Nihon University | And 4 more authors.
Polymer Degradation and Stability | Year: 2014

Using thermogravimetric (TG/DTG) analysis, we evaluated the thermal degradation characteristics of transparent poly(methyl methacrylate) (PMMA)/silica nanoparticle hybrid films obtained by well dispersing surface-unmodified silica (SiO2) nanoparticles, of average particle size approximately 15 nm, in poly(methyl methacrylate), of weight-average molecular weight (Mw) 9.6 × 104 as synthesized by radical solution polymerization of methyl methacrylate (MMA). The TG/DTG curve of a secondary aggregated opaque hybrid film, comprising SiO2 nanoparticles of size greater than several hundreds of nanometers, was in substantial agreement with that of pure PMMA. What was surprising, however, was that in the transparent hybrid, weight reduction due to cleavage of head-to-head bonds in PMMA occurring around 200 °C was nearly completely absent, and DTG peaks originating from cleavage of head-to-tail bonds and allylic-position cleavage of terminal vinylidene double bonds increased. These thermal degradation behaviors can be explained by the hypothesis of a specific chemical reaction between tertiary terminal macroradicals produced by cleavage of head-to-head bonds and silanol (SiOH) on the SiO2 nanoparticle surface. © 2014 Elsevier Ltd. All rights reserved.


Tadano T.,NIKKA SEIKO CO. | Zhu R.,Nihon University | Zhu R.,NIPPON CHEMI - CON Co. | Muroga Y.,Nihon University | And 4 more authors.
Polymer Journal | Year: 2015

Using polydisperse poly(methyl methacrylate) (PMMA) and SiO 2 nanoparticles with an average particle diameter of ~15 nm, transparent PMMA/SiO2 hybrid films could be fabricated based on the agglomeration mechanism of nanoparticles in the suspension. The calculated distance between the particles in the transparent films was ∼30 nm, corresponding to the actual measured value of 31 nm obtained from the small-angle X-ray scattering intensity. Upon heating the transparent hybrid films to 140 °C, above the glass-transition temperature of PMMA, the transmittance of UV light decreased significantly with the heating time for hybrid films with Mw =9.6 × 104 and a critical molecular weight (Mc) of 3 × 104 or greater, at which PMMA chains show effective entanglement. However, for hybrid films with Mw =0.3 × 104 and with the c or a lower molecular weight, the initial high transmittance was sustained over the entire wavelength range even after a long period of heating, and no agglomeration of the SiO2 nanoparticles was observed. Such molecular weight dependence was also observed for monodisperse PMMA/SiO2 hybrid films, leading to an examination of the difference in the rates of polymer chain entanglement and disentanglement. © 2015 The Society of Polymer Science, Japan (SPSJ) All rights reserved.


A protective film material for protecting a surface of a wafer during a laser processing treatment contains a water soluble poly-N-vinyl acetamide. The protective film material is applied to the surface of the wafer which is then irradiated with a laser beam through the protective film material to perform a laser processing treatment. After the laser processing treatment, the protective film material is removed by washing with water.

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