| Código SH | 216057 |
| Nome Do Produto | KURARAY POVAL 28-99 LA |
| Nome Químico | álcool polivinílico |
| Número Cas | 9002-89-5 |
| Fórmula Molecular | (C2H4O) n |
| Aparência | Pó granular branco |
| Viscosidade Solução A 4 Aq A 20 C | 26.0-300,0 mPa · s |
| Grau De Hidrólise | 98.8-990,8 mol% |
| Ph Solução A 4 Aq | 5,0-7,0 |
| Teor De Cinzas | ≤0,3% |
| Matéria Volátil | ≤5,0% |
| Solubilidade | Solúvel em água quente; insolúvel em solventes orgânicos |
| Densidade | Aprox. 1,3 g /cm³ |
Como uma fábrica acreditada KURARAY POVAL 28-99 LA, aplicamos protocolos de qualidade rigorosos - cada lote é submetido a testes rigorosos para garantir padrões de eficácia e segurança consistentes.
| Embalagem | KURARAY POVAL 28-99 LA é embalado em sacos de papel de parede múltipla de 25 kg com um forro interno de plástico para proteção contra umidade. |
| Carga de contêiner (20' FCL) | Carregamento de contêiner FCL 20 de KURARAY POVAL 28-99 LA, embalado com segurança em sacos, garantindo transporte seguro e estabilidade. |
| Envio | KURARAY POVAL 28-99 LA é enviado como um pó seco e de fluxo livre em sacos de papel multicamadas ou sacos de tecido PP com barreira de umidade. Não é perigoso sob transporte normal, mas requer condições limpas e secas, proteção contra chuva e umidade e rotulagem adequada para manuseio e armazenamento seguros. |
| Armazenamento | Guarde KURARAY POVAL 28-99 LA em seu recipiente original bem fechado em uma área fria, seca e bem ventilada. Proteja da umidade, umidade, luz solar direta e calor excessivo. Mantenha longe de fontes de ignição e materiais incompatíveis. Mantenha a temperatura ambiente moderada e um ambiente limpo, garantindo que os recipientes permaneçam intactos e claramente rotulados. |
| Prazo de validade | Armazene no recipiente original, bem fechado, em local fresco e seco. A vida útil é normalmente de 24 meses a partir da data de fabricação. |
Na fundição de fita cerâmica para substratos cerâmicos co-queimados a baixa temperatura, KURARAY POVAL 28-99 LA é aplicado como ligante temporário em um sistema de deslizamento aquoso onde o transporte residual de metais alcalinos deve ser limitado para evitar a perda dielétrica e a migração do condutor de prata durante a co-queimadura. após o resfriamento a 25-30 °C, a solução é mantida a vácuo por 2-4 h para remover o ar arrastado. A especificação relevante para o controle do processo é uma viscosidade de solução aquosa de 4% de 27–29 mPa·s a 20 °C por JIS K6726, com um grau de hidrólise de 99,0–99,8 mol% que deixa grupos residuais mínimos de acetato e, assim, reduz a plastificação do filme ligante seco pela umidade atmosférica. Em um deslizamento de alúmina ou vidro-cerâmica, os sólidos ligantes são medidos em 4-8% em peso do pó inorgânico, com plastificante em 2-4% em peso do pó e um dispersante de polieletrólito em 0,5-1,0% em peso. O deslizamento é fresado até que não permaneçam aglomerados visíveis, amortiguado e lançado através de uma lacuna da lâmina de comprimento de 100-300 µm em um transportador de tereftalato de polietileno a uma velocidade de linha de 0,5-1,5 m/min. A secagem é controlada a 60-80 °C, produzindo uma espessura de fita verde de 50-200 µm; a experiência de produção mostra que o ar secador acima de 85 °C cria uma pele superficial que prende a água residual e provoca enrolamento ou delaminação durante o blanqueamento, enquanto a tensão do veículo acima de 50 N/m pode iniciar rachaduras transversais na saída da lâmina. Antes da laminação, as folhas verdes são armazenadas abaixo de 40% RH para evitar a mudança dimensional da captação de umidade. As folhas verdes são blanqueadas, serigrafiadas com pasta condutora de prata ou cobre, laminadas e sinterizadas de acordo com o sistema inorgânico; Os componentes terminais incluem módulos cerâmicos co-encendidos a baixa temperatura, substratos de sensores e folhas de interconexão de cerâmica multicamada. A qualidade do substrato queimado é verificada por ASTM C373-18 para a densidade queimada e por procedimentos internos de extração de óxido de sódio porque a designação LA visa o processamento cerâmico sensível a contaminantes; Os limites exatos de álcali devem ser extraídos do certificado de análise do lote.
Preços competitivos KURARAY POVAL 28-99 LA que se ajustam ao seu orçamento - termos flexíveis e orçamentos personalizados para cada pedido.
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KURARAY POVAL 28-99 LA is a fully hydrolyzed polyvinyl alcohol resin in which the “28” designation corresponds to a nominal 4% aqueous solution viscosity of 28.0–32.0 mPa·s at 20°C when measured according to JIS K6726, and the “99” designation indicates a saponification degree of 99.0–99.8 mol%. The LA suffix identifies a low-ash variant. The resin is supplied as white to pale yellow granules or powder with a degree of polymerization of approximately 1,700. Its molecular backbone contains residual vinyl alcohol and vinyl acetate units; the residual acetyl content is below 1.0 mol%. This fully hydrolyzed structure imparts high crystalline packing density, high dry-film tensile strength, and low cold-water solubility relative to partially hydrolyzed grades. Aqueous dissolution requires deliberate thermal input; ambient swelling without heating is insufficient for complete solubilization. The low-ash designation is not a marketing descriptor but a measurable compositional parameter that becomes critical in ceramic binder systems, electronics-grade adhesive films, and any process in which residual sodium or other alkali metal content must be minimized.
Under the ISO 15023-1 designation system, polyvinyl alcohol grades are classified by degree of hydrolysis and viscosity grade. POVAL 28-99 LA falls within the fully hydrolyzed band, with a degree of hydrolysis exceeding 99.0 mol%. The viscosity grade of 28 reflects a medium-high molecular weight that is used where wet tensile strength, film toughness, and high-shear slurry viscosity are required without the handling difficulties of extremely high-molecular-weight grades. The LA suffix modifies the ash concentration, not the polymer backbone. For POVAL 28-99 LA, supplier technical data list ash as Na₂O at ≤0.10 wt% by JIS K6726, compared with conventional POVAL 28-99, which may exhibit ash up to 0.7 wt% as Na₂O. This difference originates from the removal of saponification-derived sodium acetate and other inorganic residues during post-saponification washing. The low-ash characteristic reduces the concentration of water-extractable ionic species in the final formulation.
| Property | Test method | Typical range |
|---|---|---|
| Viscosity, 4% aqueous solution at 20°C | JIS K6726 | 28.0–32.0 mPa·s |
| Degree of hydrolysis | JIS K6726 | 99.0–99.8 mol% |
| Residual acetyl content | JIS K6726 | ≤1.0 mol% |
| Volatile matter | JIS K6726 | ≤5.0 wt% |
| Ash as Na₂O | JIS K6726 | ≤0.10 wt% |
| pH, 4% solution at 20°C | JIS K6726 | 5.0–7.0 |
| Degree of polymerization | Calculated | ≈1,700 |
The tabulated values are typical ranges from supplier technical literature and do not constitute a sales specification; shipment certification should be requested for batch-level control.
In tape-casting formulations, polyvinyl alcohol is dispersed with ceramic powder, plasticizer, and water to form a shear-thinning slurry. The binder is later removed by oxidative burnout. Residual ash in the binder becomes part of the sintered ceramic matrix. Alkali ions, principally sodium, are mobile at sintering temperatures and can alter dielectric loss, insulation resistance, and microstructural uniformity in substrate and capacitor layers. The LA-grade ash ceiling of 0.10 wt% as Na₂O is therefore not merely a purity specification; it is a process control limit for ionic contamination. A conventional grade with ash up to 0.7 wt% may still sinter acceptably in low-frequency structural ceramics, but it introduces higher ionic content. When the binder is present at 4–8 wt% of the dried ceramic green tape, a tenfold increase in binder ash can raise residual sodium in the green body by a corresponding factor. Tape-casting lines using high-shear dispersers and vacuum deairing observe that low-ash PVA reduces filter plugging from inorganic fines and improves green-tape surface uniformity. Published data for the exact dielectric performance of this specific grade are limited, so end-use qualification should include thermogravimetric burnout and post-sinter ionic analysis.
For aqueous stock preparation, the granules are dispersed into demineralized water at ambient temperature under gentle agitation. The dispersion is then heated to 85–95°C and held for 30–60 min to achieve complete solubilization. High-shear mixing during the cold phase is unnecessary and can entrain air; once the temperature exceeds 80°C, agitation should be reduced to avoid foam and shear-induced chain scission. The typical use concentration is 4–10 wt%, although heated pressure reactors may extend the practical upper limit. The 4% test viscosity of 28.0–32.0 mPa·s is measured at 20°C with a Brookfield viscometer according to JIS K6726. Fully hydrolyzed PVA solutions develop hydrogen-bonded physical gels as they cool; stock solutions should be stored at 60–80°C in jacketed or traced lines. Cooling to ≤10°C produces turbidity and gel fracture at the air-liquid interface. For spray-drying or spin coating, process engineers should specify solution temperature within ±5°C because the viscosity slope of a 10 wt% solution is steep near the gel boundary.
When POVAL 28-99 LA is selected instead of a standard 28-99 grade, the primary exchange is ionic purity at equal viscosity and hydrolysis. The polymer molecular weight and water-resistance profile do not change materially. The LA grade is therefore specified in capacitor films, interlayer dielectrics, and adhesive layers where water-extractable sodium must be below a defined limit. It is also used in transfer metallization papers and specialized paper coatings where conductivity of residual ash affects surface resistivity. In adhesive applications, low ash reduces haze and improves clarity in dried films. The lower sodium acetate residue also shifts the solution pH more tightly toward neutral; pH of a 4% solution is typically 5.0–7.0. Formulators should not assume that the low-ash grade eliminates all ionic species; other formulation ingredients, especially dispersants and defoamers, dominate conductivity in many aqueous systems.
| Grade | 4% viscosity at 20°C | Hydrolysis | Ash as Na₂O | Selection logic |
|---|---|---|---|---|
| POVAL 28-99 LA | 28.0–32.0 mPa·s | 99.0–99.8 mol% | ≤0.10 wt% | Low ionic contamination, ceramic binder, electronics |
| POVAL 28-99 standard | 28.0–32.0 mPa·s | 99.0–99.8 mol% | ≤0.7 wt% | General water-resistant films, adhesives |
| POVAL 28-98 | 28.0–32.0 mPa·s | 98.0–99.0 mol% | ≤0.7 wt% | Easier cold-water solubility, slightly lower crystallinity |
| POVAL 22-99 | 22.0–26.0 mPa·s | 99.0–99.8 mol% | ≤0.7 wt% | Lower viscosity, lower binder demand |
In formulation work, the substitution of POVAL 28-99 LA for a partially hydrolyzed grade is not a direct viscosity-for-viscosity substitution. The dissolution window of POVAL 28-99 LA begins at approximately 85°C; a comparable 98 mol% grade may fully dissolve at 70–80°C. The higher hydrolysis level produces denser interchain hydrogen bonding after film drying, which increases dry-film tensile strength and reduces cold-water sensitivity. This property is beneficial for humidity-resistant adhesives and ceramic green tapes, but it reduces rewettability in repulpable paper coatings. In emulsion polymerization, fully hydrolyzed PVA is a less effective primary protective colloid for vinyl acetate emulsions than partially hydrolyzed grades because the higher hydroxyl density alters grafting efficiency and may lower colloidal stability. POVAL 28-99 LA is therefore used in emulsion polymerization primarily as a controlled-viscosity co-stabilizer or in processes where water resistance of the dried film is valued over polymerization stabilization.
Laminated ceramic tape production uses the low-ash binder in green sheets that are cut, screen-printed with conductive paste, stacked, and pressed at elevated temperature. The binder must provide green tensile strength and lamination adhesion without leaving ionic residues that migrate into conductor lines. POVAL 28-99 LA at 4–6 wt% of ceramic solids yields green tapes with sufficient tensile strength because of the fully hydrolyzed backbone. The low ash content minimizes the introduction of sodium at the binder-oxide interface. During binder burnout in air, the polymer decomposes between 350°C and 500°C; the residual ash is approximately equivalent to the original ash content of the polymer. The processing boundary is therefore set by the temperature ramp: a slow ramp through 250–350°C prevents rapid gas evolution and tape delamination. Inert atmosphere burnout is not recommended for this grade because carbonaceous residue increases. On belt furnaces with multi-zone profiles, low-ash PVA reduces furnace residue deposits over extended runs and lowers the frequency of belt cleaning required to maintain zone-to-zone temperature uniformity.
The grade is combustible as an organic dust. Dust concentrations in air should be managed below the applicable limits of NFPA 654 or local equivalents. Aqueous solutions are not classified as dangerous goods. Food-contact use is application-dependent; polyvinyl alcohol may be permitted as a component in certain resinous and polymeric coatings under 21 CFR 175.300, 21 CFR 176.170, and 21 CFR 176.180, but grade-specific compliance must be confirmed with the supplier. REACH status should be verified because polymeric substances may be exempt from registration under Article 2(9) when the polymer definition is met. The low-ash grade does not alter the dust explosion hazard; it reduces inorganic residue only. Avoid combinations with borate or boric acid species, which form strong gel networks with the 1,3-diol units of polyvinyl alcohol and can produce intractable high-viscosity masses in processing equipment. Oxidizing agents and concentrated mineral acids degrade the polymer through chain scission and acetal formation; such additives should be evaluated before line-scale use.
