Mono-Pentaerythritol 93-99% min.(Micronized)

This product is made by using formaldehyde (concentration 37%) and acetaldehyde (purity 99%) as raw materials, and undergoing condensation reaction under alkaline conditions (sodium hydroxide solution, concentration 10%) to produce a crude product: formaldehyde and acetaldehyde are added into a reactor at a molar ratio of 4:1, the temperature is raised to 60℃, sodium hydroxide solution is slowly added dropwise to adjust the pH value to 8.5, and the reaction is stirred for 3 hours. The resulting crude product is centrifuged (speed 1200 rpm) to remove the waste liquid and obtain crude pentaerythritol crystals. Subsequently, it is purified by multi-step crystallization and classification: in the first step, the crude product is dissolved in 80°C hot water with a solid-liquid ratio of 1:4, and stirred for 30 minutes to completely dissolve it. The residue is removed by filtering through an 800-mesh filter cloth, and the filtrate is introduced into a crystallization tank, cooled to 40°C at a rate of 2°C/hour, and kept at a constant temperature for 2 hours to precipitate primary crystals, and a product with a purity of 99% is obtained after separation; in the second step, the mother liquor after separating the primary crystals is introduced into another crystallization tank, and the temperature is further reduced to 20°C, and the temperature is kept constant for 3 hours to precipitate secondary crystals, and a product with a purity of 96% is obtained; in the third step, the remaining mother liquor is evaporated and concentrated (temperature 80°C, vacuum degree - 0.08MPa) to 1/3 of the original volume, and the temperature is reduced to 10°C to precipitate tertiary crystals, and a product with a purity of 93% is obtained. Each level of crystals is processed by a jet mill, with a nitrogen pressure of 0.7MPa and a grading wheel speed of 3000 rpm, and all are made into powder with D50=5μm, namely Mono-Pentaerythritol 93-99% min. (Micronized). Among them, the hydroxyl content of the 99% grade product is 40%±0.3%, and the ash content is <0.05%; the hydroxyl content of the 93% grade product is 38%±0.5%, and the ash content is <0.1%, which can meet the use requirements of different scenarios. This process is like screening sand and finely grading according to purity, so that each level of product can be used to its full potential and become the preferred economical flame retardant carbon source.

When the 99% grade product is used in solvent-based fire retardant coatings, it is compounded with ammonium polyphosphate at a ratio of 1:4, with a total addition of 50%, mixed with acrylic resin (solid content 50%), and ground by a sand mill (speed 2000 rpm) for 30 minutes to a fineness of <50μm. The coating is applied to a steel plate (dry film thickness 0.5mm) and tested after curing for 7 days. When burning, an expanded carbon layer with a thickness of 10mm can be formed within 30 seconds. It can withstand 1000℃ flame burning for 60 minutes, and the back temperature of the steel plate does not exceed 140℃, which meets the first-level fire retardant coating standard in GB 14907-2018. The 96% grade product is used for water-based fire retardant coatings. It is mixed with expanded graphite in a ratio of 3:1, with an addition amount of 45%, mixed with styrene acrylic emulsion, and dispersed in a high-speed disperser (speed 1500 rpm) for 20 minutes. The storage stability of the coating is up to 6 months, without stratification and sedimentation; applied on the wood surface, the dry film thickness is 1mm, the adhesion is up to level 2, and after a 7-day water resistance test (immersed in water at room temperature), the coating has no wrinkles or shedding, and the flame retardant performance retention rate is 90%. The 93% grade product is suitable for thick coating fire retardant coatings. The cost is 15% lower than that of the 99% grade. The addition amount is increased by 5% (that is, the total addition amount is 55%) to achieve the same flame retardant effect. It is applied on concrete walls (dry film thickness 5mm) and the flame retardant time is up to 180 minutes, meeting the fire protection requirements of large buildings. Its ultrafine particles (5μm) can fill the pores in the coating and improve the smoothness of the dry film by 20%. Therefore, in the fields of steel structure coating, wood fire retardant paint, concrete surface fire protection, etc., different purity levels can be flexibly selected according to cost and performance requirements, taking into account both economy and practicality.

The 99% grade product is mixed with Melamine Cyanurate (MCA) in a ratio of 1:3 for nylon 6 (relative viscosity 2.8), with an addition amount of 20%, mixed and granulated by a twin-screw extruder (temperature 230-250℃), and injection molded into standard specimens. Tests show that its flame retardant performance reaches UL94 V-0 level (1.6mm), oxygen index is 31%, and tensile strength retention is 85% (up to 65MPa), which is 5% higher than that of non-ultrafine monopentaerythritol, because ultrafine particles can be more evenly dispersed in the nylon matrix, reducing the impact on mechanical properties. The 96% grade product is compounded with magnesium hydroxide (particle size 1μm) in a ratio of 1:5 for polypropylene (PP, melt flow rate 12g/10min), and the addition amount is 30%. When burning, it can promote the close combination of the carbon layer and the MgO insulation layer to form a double flame retardant barrier, extend the flame retardant time by 30%, and reduce the smoke density rating (SDR) from 60 to 45, reducing the smoke hazard in the fire. The 93% grade product is used in conjunction with red phosphorus (microcapsule coated) in a 2:1 ratio for polyethylene (PE, density 0.94g/cm³). The addition amount of 25% can reduce the amount of red phosphorus by 30%, effectively eliminate phosphorus smoke pollution, and increase the tensile strength retention rate of the product by 8%, solving the problem of mechanical properties degradation caused by excessive red phosphorus addition. Its monohydroxy structure has high reactivity and can quickly combine with various flame retardants to form a stable composite flame retardant system. Therefore, it can play a synergistic effect in different resins and flame retardant requirements, solving the problem of insufficient efficiency of a single flame retardant.

The 99% grade product can be used as a crosslinker for polyester resins due to its high purity (99%) and low impurities: in the synthesis of unsaturated polyester resins (o-phthalate type), adding 5% can increase the crosslinking density of the resin by 20%, increase the curing speed by 20% (gel time shortened from 30 minutes to 24 minutes), and enhance the chemical corrosion resistance of the cured resin. After immersion in a 30% sulfuric acid solution for 30 days, the weight loss rate is less than 1%. When used for automotive primers, the adhesion reaches level 0 (cross-cut test), meeting the requirements of high-end coatings. The 96% grade product can be used as a raw material for lubricating oil antioxidants, reacting with diphenylamine to form a composite antioxidant. Adding 0.5% to lubricating oil for engineering machinery (viscosity grade 15W-40) can improve the antioxidant properties of the oil, extend the oxidation induction period of the lubricating oil from 200 minutes to 300 minutes, extend the oil change cycle to 1.5 times, and reduce equipment maintenance costs. 93% grade products can be used as additives for polyurethane foaming agents. In the synthesis of rigid polyurethane foam, adding 3% can adjust the foaming speed, make the foam pore size uniform (50-100μm), increase the closed cell rate by 15% (up to 90%), and reduce the thermal conductivity to 0.022W/(m・K), enhancing the thermal insulation performance, and are suitable for building insulation materials. Its ultra-fine particles (5μm) can be evenly dispersed in various additive systems to make the effect more stable. Therefore, in addition to the flame retardant field, it is also widely used in additives in the chemical, building materials, automotive and other industries, realizing one material with multiple functions.

Electronic-grade products (such as automotive connectors, mobile phone charging interfaces, etc.) have extremely high purity requirements, and 99% grade products must be selected to ensure that there are no impurities affecting electrical properties (volume resistivity>10¹⁴Ω・cm). The addition amount is controlled at 8-12%, and it is compounded with Ammonium Polyphosphate (APP-3) in a precise ratio (usually 1:3) so that the product meets the UL94 V-0 flame retardant requirements and ensures good electrical conductivity and mechanical properties. For scenes with lower purity requirements such as architectural coatings and wood fire retardant paints, 96% grade products can be selected, with an addition amount of 15-20%. While ensuring flame retardant properties (flame retardant time ≥60 minutes), the cost of raw materials is reduced, and its slightly higher impurity content will not affect the construction performance and appearance of the coating. For filled products with low performance requirements, such as plastic pallets and trash cans, 93% grade products can be selected, with an addition amount of 20-25%, which can meet basic flame retardant requirements (UL94 V-2 level) and greatly reduce production costs. During storage, 99% grade products must be strictly protected from moisture (relative humidity <40%) to prevent moisture absorption and agglomeration that affect dispersion; 93% grade products can be appropriately relaxed (relative humidity <60%), but still need to avoid direct contact with water. Each level of products must be stored in separate areas and clearly marked to avoid mixing and causing product performance to fail to meet standards. During processing, stainless steel equipment (304 material) should be used for high purity levels (99%, 96%) to prevent equipment rust and contamination of products; ordinary carbon steel equipment can be used for low purity levels (93%) to reduce production equipment costs. This method of grading and selection is like tailoring to suit individual needs, so that products of different purities can play the greatest role in their respective applicable fields and maximize economic benefits.