B05HX Chang Chun PVB Resin

Chang Chun Petrochemical Co., Ltd. supplies B05HX as a polyvinyl butyral resin produced by acid-catalyzed acetalization of polyvinyl alcohol with n-butyraldehyde in aqueous suspension. The polymer contains three segment types: vinyl butyral, vinyl alcohol, and vinyl acetate. The vinyl butyral segment provides solubility in toluene, methyl ethyl ketone, lower alcohols, and ethanol/toluene blends; the residual vinyl alcohol segment contributes adhesion to metal oxides, glass, and ceramic surfaces; the residual vinyl acetate segment moderates crystallinity and compatibility with selected plasticizers and epoxy or alkyd modifiers. B05HX is specified with a residual vinyl alcohol segment in the range 18–22 mol%, a range that maintains solubility in 1:1 w/w ethanol/toluene at 10 wt% solids while retaining hydroxyl functionality for condensation with melamine-formaldehyde, urea-formaldehyde, isocyanate, and phenolic prepolymers. The material is supplied as white to off-white free-flowing granules or powder. Bulk density typically falls between 0.25 g/cm³ and 0.45 g/cm³ depending on conveying and storage compaction. Differential scanning calorimetry at 10 °C/min under nitrogen places the glass transition temperature between 68 °C and 75 °C for PVB resins of comparable composition, though batch-specific certificates of analysis should be used for engineering design.

Molecular characterization of B05HX by size-exclusion chromatography against narrow polystyrene standards typically places the weight-average molecular weight in a comparable range to other lower-viscosity PVB resins, but the polydispersity index should be confirmed because suspension acetalization produces a different molecular weight distribution than solution-polymerized grades. A polydispersity index between 2.0 and 3.0 is common for suspension-acetalized PVB resins, whereas solution-acetalized grades can be narrower. This distribution influences re-dissolution time in solvent blends: B05HX granules dissolve under low-shear agitation with a pitched-blade turbine at 150 rpm and 25–35 °C in toluene/ethanol blends within 45–90 min when pre-dried to ≤ 0.2 wt% moisture. If water content exceeds 1.0 wt%, dissolution time extends beyond 2 h and the resulting solution may show a haze point above 5 °C. Resin producers therefore control drying after washing on fluidized-bed dryers at inlet air temperatures below 60 °C to avoid particle softening and agglomeration. The high vinyl alcohol segment content relative to low-hydroxyl PVB grades raises room-temperature solution viscosity in alcohol-rich blends; this behavior is used in formulations that need higher shear viscosity without adding silica or castor-oil thixotropes.

For incoming quality control, B05HX is characterized by solution viscosity, residual acetate and hydroxyl content, moisture, and residue on ignition. Representative values from distributor documentation are listed below; they are not a substitute for a certificate of analysis.

What Single-Point Viscosity Misses in Reverse-Roll Wash Primer Application

In coil coating lines that apply wash primers by reverse-roll transfer at 100–140 m/min, the solution viscosity of B05HX measured at 10 wt% in 1:1 w/w ethanol/toluene at 25 °C is a necessary but insufficient specification. Two batches with the same Brookfield spindle-2 reading of 50 mPa·s can differ in high-molecular-weight tail when the acetalization reactor temperature drifts or when the polyvinyl alcohol feedstock has different solution viscosity. On a three-roll coater set with a 20 µm wet-film gap, a high-molecular-weight fraction above 1.5 × 10⁵ g/mol by gel permeation chromatography against polystyrene standards promotes ribbing and orange-peel transfer at the trailing nip because the elongation-dominated film split is more sensitive to the high-molecular-weight tail than to bulk viscosity. Production-scale line checks on reverse-roll equipment with 250 mm roll width and 0.3–0.5 MPa nip pressure have shown that the defect appears even though the single-point viscosity remains within the 45–70 mPa·s window. Qualification for high-speed reverse-roll coating therefore combines Brookfield viscosity with gel permeation chromatography and a cone-and-plate high-shear viscosity sweep at 1000 s⁻¹ using a rheometer operated under ISO 3219-aligned conditions. The high-shear viscosity should remain below 80 mPa·s at 1000 s⁻¹ to avoid transfer roll pattern formation; above that threshold, solvent adjustment alone cannot correct the film-split instability without reducing application solids below the target dry-film thickness.

Wash primer formulations based on B05HX commonly use a two-component system in which the PVB resin is dissolved in an alcohol/ketone blend and mixed with a phosphoric acid activator and a zinc phosphate or zinc tetroxychromate pigment. The vinyl alcohol segment coordinates to zinc phosphate and iron oxide surfaces, but free acid below pH 2.0 accelerates acetal hydrolysis; therefore the pot life after activation is typically controlled to 4–8 h at 25 °C. Adhesion and salt spray resistance on cold-rolled steel are evaluated by crosshatch after 24 h and after 500 h neutral salt spray according to ISO 9227:2022. The coating is applied to a dry-film thickness of 8–12 µm; heavier films can crack over sharp edges, and the acid-activated primer is not intended to replace the main anticorrosive coating.

Gravure and flexographic ink manufacturing with B05HX typically begins with dissolution at 25–35 wt% resin solids in a blend of ethyl acetate, ethanol, and toluene or methyl ethyl ketone. High-shear dispersion on a horizontal bead mill charged with 0.8–1.0 mm yttrium-stabilized zirconia media at tip speeds of 8–12 m/s permits pigment loading up to 35 wt% in the dispersed paste before letdown, provided the resin solution viscosity remains below 70 mPa·s at 25 °C. The vinyl alcohol segment of B05HX participates in hydrogen bonding with oxidized carbon black, treated titanium dioxide, and alkali-treated aluminum pigments, which reduces pigment flocculation after 24 h of storage at 40 °C. Adhesion to corona-treated polyethylene and polyester films is evaluated by crosshatch tape removal after conditioning at 23 °C and 50 % RH for 24 h using ISO 2409:2020. In nitrocellulose-modified ink vehicles, B05HX is used as a co-binder at 5–20 wt% of total binder solids because higher additions raise the low-shear viscosity at the doctor blade and produce solvent-release cracking on high-speed rotogravure cylinders. The solvent blend is adjusted so that the final ink viscosity at press is 18–25 s in a Zahn cup #2 at 25 °C; this range prevents skipping at the gravure cell without causing trailing-screen plugging.

When B05HX Is Compounded with Plasticizer for Laminated Glass Interlayers

B05HX is not the highest-viscosity PVB grade in the Chang Chun portfolio; it is therefore assigned more often to solvent-cast film, edge-seal, and primer applications than to primary melt-extruded safety-glass interlayer. Plasticizer uptake is controlled by the residual vinyl alcohol content. With triethylene glycol di-2-ethylhexanoate or dioctyl adipate, B05HX formulations typically accept 20–35 phr plasticizer before phase exudation is observed after 14 days at 60 °C. Laminated glass adhesion to tin-side float glass is evaluated after autoclave lamination at 135–140 °C and 1.1–1.3 MPa for 30–60 min. Peel force is measured at 180° and 50 mm/min using a tensile specimen geometry adapted from ASTM D638-14; the value is not directly comparable to structural adhesive peel methods because PVB is a tough, rate-dependent material. Published data for B05HX specifically in standard safety-glass interlayer configurations is limited, so windshield-grade optical and penetration-resistance requirements require validation with the specific plasticizer, glass surface condition, and moisture level. For edge-seal and solvent-cast film applications, the lower viscosity of B05HX allows coating at 35–45 wt% solids without solvent entrapment, but dry-film adhesion should be checked after 72 h at 50 °C because retained solvent can plasticize the bond and reduce shear strength.

Distributor selection guides for the Chang Chun PVB range distinguish B05HX from adjacent grades by solution viscosity and residual vinyl alcohol content. The following representative positions are used for solvent-borne formulation screening; exact values should be confirmed with the manufacturer.

Compared with low-hydroxyl PVB resins used in high-solids coatings, B05HX provides stronger hydrogen-bonding adhesion to untreated metal surfaces but is less tolerant of aromatic-only solvent blends and exhibits a higher room-temperature solution viscosity at equal solids. The solubility sphere is closer to blends containing at least 20 wt% alcohol or glycol ether in the solvent system. Compared with higher-viscosity PVB grades in the same producer portfolio, B05HX lowers the required letdown solvent for a given press viscosity and is preferred when the formulation already contains high-surface-area pigments such as carbon black or fumed silica. B05HX is not the grade of choice when the requirement is maximum tensile strength in plasticized film at low plasticizer levels; higher-viscosity PVB grades are typically evaluated for those applications.

Low-temperature co-fired ceramic tape formulations have used PVB resins because the acetal backbone decomposes in air between 250 °C and 450 °C. The residue on ignition specification of ≤ 0.15 wt% after 750 °C for B05HX is relevant to sintered dielectric loss targets, but the burnout profile is also sensitive to tape thickness, ceramic powder packing, and heating rate. In tape casting with a doctor blade gap of 150–250 µm, heating rates above 2 °C/min between 250 °C and 450 °C can blister the tape because decomposition gases cannot escape through the densified surface skin before the ceramic particles begin to consolidate. A stepped profile of 0.5–1.5 °C/min through this decomposition window is common. Thermogravimetric analysis under air at 10 °C/min should be used to verify that the organic residue is below 0.1 wt% at 450 °C for the specific tape formulation. Published data for B05HX in specific low-temperature co-fired ceramic systems with exact dielectric powder blends is limited; therefore each dielectric supplier validates the burnout curve, green tape tensile strength, and lamination behavior with the intended powder surface treatment.

Solvent-free compounding of B05HX with plasticizer and tackifier on a 40:1 L/D co-rotating twin-screw extruder requires a temperature profile that limits shear-induced acetal degradation. The feed zone is maintained at 80–110 °C, the mid-barrel zones rise to 150–170 °C, and the die is held below 180 °C. Screw speeds above 300 rpm can raise the melt temperature by 10–15 °C above the barrel set point and generate acetaldehyde and crotonaldehyde byproducts that reduce melt stability and create odor in the finished compound. Vacuum devolatilization at -0.08 MPa is applied upstream of the die to withdraw moisture and residual solvents. Die melt pressure is maintained below 8 MPa to avoid back-flow over the screw flights and to reduce residence time distribution. On a 25 mm co-rotating twin-screw extruder, throughput stability of 15–25 kg/h is sensitive to bulk density variation; gravimetric feeding with vertical hopper agitation is recommended. The same melt processing limits apply when B05HX is used as a carrier resin for pigment masterbatches in solvent-free ink systems, where pigment dispersion is assessed by a 25 µm grind gauge under a film applicator.

Adhesive and sealant formulations select B05HX when the mixed system must remain below 100 mPa·s at 30 wt% solids in methyl ethyl ketone. The resin is combined with epoxy or phenolic tackifiers and with silane coupling agents; however, alkaline fillers that shift the formulation pH above 9.0 accelerate hydrolysis of the vinyl butyral segment at storage temperatures above 40 °C. In epoxy-modified PVB primers, aliphatic amines should not be preblended with B05HX before application because they can raise pH and promote acetal hydrolysis during storage; amine curing agents are better added as a second component. In two-part polyurethane reactive adhesives, the residual hydroxyl participates in NCO/OH curing; the preferred stoichiometry is calculated at 1.05–1.15 NCO index to offset moisture interference without leaving excess free isocyanate that migrates to the bondline and acts as a plasticizer. Accelerated aging at 70 °C and 85 % RH for 7 days is used to compare shear strength retention on degreased aluminum coupons prepared with 180-grit abrasion and an acid etch pretreatment. For clear film or adhesive applications, B05HX should be dried to ≤ 0.2 wt% moisture before dissolving if ambient relative humidity exceeds 60 %, because wet granules slow dissolution and can introduce haze in clear films. The dry resin should not be directly mixed with strong oxidizing acids or with concentrated sulfuric acid; premature acetal hydrolysis generates butanal and reduces the hydroxyl functionality required for thermoset cure.

Regulatory position for B05HX should be confirmed with Chang Chun Petrochemical documentation. For food-contact ink and adhesive applications, end users typically evaluate the formulated article under 21 CFR 175.300 or 21 CFR 175.105 as applicable, rather than relying solely on the resin composition. European Union compliance under REACH requires the registrant’s exposure scenario for industrial use; the resin is not classified as a polymer of concern under standard hazard classes, but acetaldehyde released during high-temperature processing above 180 °C is a regulated decomposition product and should be controlled by local exhaust ventilation. The resin should be stored below 30 °C and protected from moisture to maintain dissolution rate.