Manufacturer	Production Process	Production Capacity (10,000 tons)	Device Status
Chemical Business Division, Shanghai Petrochemical Co., Ltd.	Ethylene from Petroleum	4.6	Partially running
China Petrochemical Corporation Chongqing Chuanwei Chemical Co., Ltd.	Acetylene from Natural Gas Method	16	Run
Anhui Wanwei High‑Tech Materials Co., Ltd.	Calcium Carbide Acetylene Process	6.0 (Anhui Unit)	Run
Bioethylene Process	5.0 (Guangxi Unit)	Run
Calcium Carbide Acetylene Process	20.0 (Inner Mongolia Unit)	Run
Taiwan Changchun Group	Ethylene from Petroleum	12.0 (Jiangsu)	Run
Ningxia Dadi Circular Development Co., Ltd.	Calcium Carbide Acetylene Process	13	Run
Inner Mongolia Shuangxin Environmental Protection Materials Co., Ltd.	Calcium Carbide Acetylene Process	13	Run
Sinopec Great Wall Energy & Chemicals (Ningxia) Co., Ltd.	Calcium Carbide Acetylene Process	10	Run
Hunan Xiangwei Co., Ltd.	Calcium Carbide Acetylene Process	10	Partially running
Total	109.6

Polyvinyl Alcohol (PVA) is an important polymer material. The following is a detailed introduction to it:

I. Basic Information

• Chinese Name Polyvinyl alcohol

• English name Polyvinyl Alcohol, vinyl alcohol polymer

• Chemical formula [C2H4O]n

• Molecular weight It varies depending on the degree of polymerization, typically ranging from 5,000 to 200,000.

• CAS Registry Number :9002-89-5

II. Physical Properties

• Appearance White flaky, fibrous, or powdery solid with no odor.

• Water-soluble Soluble in water; to ensure complete dissolution, it generally needs to be heated to 65–75°C.

• Insoluble It is insoluble in gasoline, kerosene, vegetable oils, benzene, toluene, dichloroethane, carbon tetrachloride, acetone, ethyl acetate, methanol, and ethylene glycol, but slightly soluble in dimethyl sulfoxide; it becomes soluble in glycerin at 120–150°C.

• Density : 1.19–1.31 g/cm³

• Melting point : 212–267°C (some sources indicate 230°C)

• Boiling point Approximately 340°C

• Glass transition temperature 75–85°C

• Other Physical Properties It is influenced by chemical structure, degree of alcoholysis, and degree of polymerization. For example, as the degree of polymerization increases, the viscosity of aqueous solutions rises, and the strength and solvent resistance of the resulting film improve; however, water solubility decreases, and the elongation at break of the film also declines.

III. Chemical Properties

• Alcoholysis reaction Polyvinyl acetate is produced by the polymerization of vinyl acetate, which is then converted into polyvinyl alcohol via an alcoholysis reaction.

• Degradation in strong acids It will degrade in strong acids.

• Softening or dissolving in weak acids and weak bases. It will soften or dissolve in weak acids and weak bases.

• Combustion and Explosion Contact with strong oxidizers can cause combustion and explosion, and dust mixed with air can form explosive mixtures.

IV. Properties of PVA Materials

Polyvinyl alcohol (PVA) is a… Water-soluble polymers Its chemical formula is [C2H4O]n. It appears as a white, flaky, fibrous, or powdery solid with no odor. It is characterized by excellent compactness and high crystallinity, strong adhesion, and the ability to produce flexible, smooth films that are oil‑resistant, solvent‑resistant, abrasion‑resistant, and highly gas‑barrier. Additionally, after special treatment, it exhibits water resistance, making it suitable for a wide range of applications.

It is non-toxic, odorless, and harmless to the human body, exhibiting excellent compatibility with the natural environment—non‑accumulative and pollution‑free. Polyvinyl alcohol film is a green, eco‑friendly functional material whose primary component is polyvinyl alcohol, enhanced with modifiers and other additives, and which can be completely degraded by microorganisms in the soil through a specialized manufacturing process. It decomposes into carbon dioxide and water within a short period of time and also helps improve soil quality. The greatest advantage of polyvinyl alcohol film is its water solubility; its most significant drawback, however, is its poor water resistance.

The reason for its poor water resistance is that… The molecule contains hydrophilic hydroxyl groups (-OH). If the hydroxyl groups can be appropriately capped and replaced with hydrophobic functional groups, the water resistance of PVA films can be significantly improved. PVA contains hydroxyl groups and is capable of undergoing all the typical reactions associated with polyols. By selecting an appropriate polycondensate, even at relatively low addition levels, it is possible to achieve moderate crosslinking with the hydroxyl groups in PVA, thereby forming a robust three-dimensional structure that stabilizes PVA’s gas tightness under humid conditions and enhances its water resistance. In practical applications, the water solubility and hygroscopicity of polyvinyl alcohol films can be controlled by adjusting the raw materials, formulation, and processing parameters, thus meeting the requirements of different end‑use scenarios.

V. Main Uses

1. Textile Industry As a textile sizing agent, it enhances fiber strength and luster while also serving as a raw material for vinylon fibers, which can be used to produce synthetic fibers that are high‑strength, high‑modulus, abrasion‑resistant, and corrosion‑resistant.

2. Papermaking Industry As a coating agent for papermaking, it enhances the smoothness, brightness, water resistance, and oil resistance of paper. It can also be used as an additive in security paper to increase its level of security.

3. Architecture field It is used to manufacture PVA films, a biodegradable, environmentally friendly material that can be employed for agricultural mulch, water‑soluble packaging bags, and water‑soluble sutures, among other applications.

4. Pharmaceutical field As a drug carrier, it can be co‑dissolved or compounded with pharmaceuticals to formulate various dosage forms such as tablets, capsules, and injectables, thereby enhancing the solubility, bioavailability, and sustained-release properties of drugs. At the same time, polyvinyl alcohol is also widely used in ophthalmology, wound dressings, and artificial joints. In addition, it can be used to produce polyvinyl alcohol films for applications like medicinal membranes and artificial kidney membranes.

5. Food Industry As a food additive, it can enhance the stability, viscosity, and water retention of foods, and is used in the production of ice cream, jelly, jam, and other such products.

6. Other fields It can also be used to prepare photosensitive adhesives and sealants resistant to benzene-based solvents, as well as release agents, dispersants, and more. In addition, it can be used to manufacture lubricants, ointments, lotions, and antifreeze agents, among others.

7. Biomedical

Due to their large surface area‑to‑volume ratio, high porosity, sufficient permeability, excellent wound exudate absorption capacity, structural similarity to skin extracellular matrix (ECM), superior antibacterial properties, long‑term sustained release characteristics, and good biocompatibility, they can be used as wound dressings, cell scaffolds, and for in vitro tissue engineering, among other applications. A research team has summarized electrospun PVA nanofibers for wound healing and highlighted their significant potential for future development in the biomedical field.

8. Sound-absorbing materials

Traditional sound‑absorbing materials mainly include acoustic cotton, space‑absorbing panels, perforated panels, and sound‑absorbing foam. Compared with these conventional materials, electrospun PVA nanofiber materials boast characteristics such as small nanofiber diameters, a large specific surface area, tiny pore sizes, and lightweight construction—features that are highly conducive to enhancing sound absorption performance. Several research teams have already applied PVA materials to sound‑absorbing applications, enabling the material to efficiently convert the effects of air viscosity, heat conduction, fiber vibration, and friction on sound energy into mechanical or thermal energy losses. This holds tremendous potential for advancing the field of sound absorption and noise reduction.

Figure 2: Research Progress on the Sound Absorption Performance of Electrospun Fiber Composites

9. Heavy Metal Ion and Dye Adsorption Materials

Heavy metal ion contamination and organic dye compound pollution pose severe threats to both the ecological environment and human health. Due to the large number of side groups—–CN—on PVA macromolecules, and the highly polar and reactive nature of –CN, PVA can undergo physical or chemical interactions with numerous small-molecule compounds, enabling the modification of PVA fibers and endowing them with new, desired properties. In particular, by aminating or hydrazinylating the surface of PVA nanofibers to introduce amino or hydrazinyl groups that exhibit adsorptive activity, these groups can form coordination bonds with metal ions. PVA nanofibers boast advantages such as small fiber diameters and high specific surface areas. Several research teams have employed electrospinning of PVA materials for heavy metal adsorption, which holds significant potential for advancing applications in areas such as heavy metal ion adsorption and dye removal.

10. Battery separator

As one of the crucial components in lithium-ion batteries, the performance of the separator directly affects the overall battery performance. PVA composite separators outperform traditional separators in terms of porosity, liquid absorption rate, and even thermal decomposition temperature. Moreover, the shrinkage and swelling rates of PVA composite separators remain at low levels. By applying electrospun PVA materials to battery separators, the research team has advanced the development of lithium-ion batteries.

PVA–ZrO₂ Multilayer Composite Separator for Enhancing the Performance and Mechanical Strength of Lithium-Ion Battery Electrolytes

VI. Toxicity and Safety

• Toxicity Polyvinyl alcohol itself is non-toxic and has no side effects on the human body, but safety precautions should still be observed during use. Prolonged or excessive exposure may cause skin irritation, allergic reactions, or respiratory discomfort.

• Explosive hazard This product is combustible and irritating. Avoid contact with open flames, high temperatures, sparks, static electricity, and other ignition sources to prevent fires.

• Protective Measures When using polyvinyl alcohol, appropriate protective equipment such as gloves, a mask, and goggles should be worn to avoid inhalation or contact with skin and eyes.

VII. Preparation and Synthesis

Polyvinyl alcohol is produced by the polymerization and alcoholysis of vinyl acetate (VAc). There are typically two raw material routes for PVA production:

Ethylene Process Vinyl acetate is directly synthesized from ethylene produced via petroleum cracking, which is then used to manufacture polyvinyl alcohol. This method boasts large-scale production, high product quality, easy maintenance, management, and cleaning of equipment, high thermal efficiency, significant energy savings, and relatively low production costs.

Acetylene Process Vinyl acetate is produced from acetylene—divided into calcium carbide acetylene and natural gas acetylene—as a raw material, which is then used to manufacture polyvinyl alcohol. This method is relatively simple to operate, boasts high yields, and allows for easy separation of byproducts. However, the high-alkali acetylene process features high energy consumption, poor product quality, and high costs. Moreover, the impurities generated during production cause significant environmental pollution, resulting in a lack of market competitiveness and making it a gradually phased‑out process. While the natural gas acetylene process benefits from mature technology and produces acetylene that is well suited for comprehensive utilization, it also entails substantial investment and technical challenges.

The synthesis process of polyvinyl alcohol is as follows:

1. Vinyl Acetate Polymerization Reaction

2. Alcoholysis Reaction (Different high‑grade polyvinyl alcohols can be obtained depending on the alcoholysis process.)

The alkaline alcoholysis of polyvinyl acetate is divided into wet-process methods. ( High alkalinity ) And dry method ( Low alkalinity ) Two types.

Wet alcoholysis refers to a process in which the methanol solution used for alcoholysis contains 1–2% water, and the alkaline catalyst is also prepared as an aqueous solution. The characteristics of wet alcoholysis include a fast reaction rate, high production capacity, and a compact footprint; however, it suffers from numerous side reactions and produces large amounts of sodium acetate. The low-alkali method can be used to produce a series of products with esterification degrees of 98, 97, 95, 92, and 88 (the numbers represent the degree of alcoholysis of the ester group), whereas the high-alkali method is limited to producing only 99‑grade products.

Dry alcoholysis refers to a process in which the polyvinyl acetate–methanol solution contains no water, and the alkali is dissolved in methanol. The advantages of dry alcoholysis overcome the drawbacks of wet alcoholysis; however, its alcoholysis rate is slow, resulting in long residence times for the materials, which poses challenges for continuous production. Both high-alkali and low-alkali processes can produce 99%‑purity products.

 

3. Saponification Reaction

Attention During the process of partially hydrolyzing polyvinyl acetate to produce polyvinyl alcohol, large quantities of hydrolysis waste liquid (also known as recovered stock solution) are generated. Its main components include methanol, methyl acetate, sodium acetate, and acetaldehyde, which require a specialized recovery and treatment process.

 

The alcoholysis of polyvinyl alcohol cannot be directly obtained through monomer polymerization; instead, it is prepared by the alcoholysis or hydrolysis of its ester, polyvinyl acetate. In industrial production, the alkaline alcoholysis method is widely used to prepare PVA because the PVA produced via alcoholysis is easy to purify, boasts high purity, and exhibits superior performance in the main product. The alcoholysis reaction under alkaline conditions can be carried out using either a wet process or a dry process—namely, the high-alkali method and the low-alkali method. At present, the low-alkali alcoholysis method has become the primary approach for manufacturing polyvinyl alcohol.

8. Process Flow

Polyvinyl alcohol is a polyhydroxy polymer with the molecular formula (C₂H₄O)ₙ, which can also be represented as (CH₂CHOH)ₙ(CH₂CHOCOCH₃)ₘ. Here, m + n denotes the average degree of polymerization; (CH₂CHOH)ₙ represents the vinyl alcohol unit, while (CH₂CHOCOCH₃)ₘ indicates the residual vinyl acetate unit. The ratio m/n should range from 0 to 0.35, because the vinyl alcohol monomer is unstable and polyvinyl alcohol cannot be directly synthesized from vinyl alcohol monomers—it can only be produced via the hydrolysis of polyvinyl acetate.

Polyvinyl alcohol production is divided into three key steps, each corresponding to a specific chemical reaction. Throughout the entire process, temperature, pressure, and catalyst dosage must be carefully controlled to ensure complete reactions and enhance product purity. Industrial facilities employ continuous production processes, equipped with tail gas recovery systems and wastewater treatment equipment.

Ethylene vinyl acetate synthesis is the primary step. Acetylene gas is passed into an acetic acid solution, where it undergoes an addition reaction under the catalytic action of a zinc acetate catalyst supported on activated carbon. The reaction temperature is maintained at 180–200°C, and the pressure is controlled at 0.3–0.5 MPa. While ethylene vinyl acetate monomer is produced, a small amount of byproducts are also generated and must be separated and purified via a distillation column. The main reaction equation is: HC≡CH + CH3COOH → CH2=CHOOCCH3

Vinyl acetate polymerizes to form polyvinyl acetate. Under the action of the initiator benzoyl peroxide, multiple monomer molecules are linked together via a free-radical polymerization mechanism to form long-chain polymers. The reactor temperature is maintained at 60–70°C, with a reaction time of approximately 6–8 hours and a conversion rate exceeding 95%. The reaction equation is: n CH2=CHOOCCH3 → [CH2-CH(OOCCH3)]n

The alcoholysis process determines the final product performance. Polyvinyl acetate is dissolved in methanol, and sodium hydroxide is added to carry out an ester exchange reaction. The degree of alcoholysis is controlled within the range of 88–99%, with the temperature maintained at 40–50°C for 4 hours. The reaction produces polyvinyl alcohol and the byproduct methyl acetate, which can be recovered and recycled for use in acetic acid production. The reaction equation is: [CH2–CH(OOCCH3)]n + n NaOH → [CH2–CH(OH)]n + n CH3COONa

9. Introduction to Polyvinyl Alcohol Production Routes

The production routes for polyvinyl alcohol are generally divided into two categories: the acetylene method (which is further subdivided into calcium carbide acetylene and natural gas acetylene) and the ethylene method (which includes petroleum-based ethylene, natural gas-based ethylene, and biomass-based ethylene), as shown in Figure 1.1.

Figure 1.1: Polyvinyl Alcohol Production Process Routes

Calcium carbide acetylene process,

It is the earliest technology to achieve industrialized production, with mature process technology: limestone → calcium carbide → acetylene → vinyl acetate → polyvinyl acetate → polyvinyl alcohol. Although this method is relatively simple to operate, requires low investment, produces high‑purity acetylene with high yield, allows for easy separation of byproducts, and uses readily available catalysts, it also causes relatively severe environmental pollution, and the calcium carbide slag is difficult to dispose of. Moreover, the acetylene process features high levels of aldehydes, sulfur, and phosphorus, along with substantial electricity consumption and raw material usage, making its long‑term development prospects not particularly optimistic [5].

Acetylene method using natural gas,

The process route for synthesizing VAC includes desulfurization and partial oxidation cracking of natural gas, acetylene concentration, VAC synthesis and distillation, and acetic acid recovery. Although the acetylene produced by this method has low purity, the raw materials are relatively inexpensive, energy consumption is low, and costs are reduced. Moreover, the tail gas can be put to comprehensive use, resulting in production costs that are 50%–70% lower than those of the calcium carbide–acetylene method. This route is the preferred process for regions rich in natural gas or oil and gas resources. However, the natural gas–acetylene route requires substantial investment and poses high technical challenges.

Ethylene production via petroleum cracking,

It is a process method that was first successfully developed and put into industrial production by Kureha Co., Ltd. of Japan (formerly Kurashiki Rayon Co., Ltd.). The process flow comprises six stages: vaporization of acetic acid, synthesis of vinyl acetate (VAC), distillation of VAC, polymerization of VAC, alcoholysis of polyvinyl acetate (PVAc), and recovery of acetic acid and methanol. The key characteristics of the petroleum-based ethylene process are: larger production scale compared to the acetylene process, higher product quality, a shorter process flow with fewer pieces of equipment that are easier to maintain, manage, and clean; low steam consumption and high thermal energy utilization, resulting in significant energy savings and production costs that are 30% lower than those of the acetylene process.

Bioethylene method,

PVA is produced using the ethanol–ethylene process, with a process flow that proceeds as follows: tuber crops and sugarcane → ethanol → ethylene → vinyl acetate → polyvinyl acetate, which is ultimately hydrolyzed to yield polyvinyl alcohol. This process represents the world’s first biomass‑derived ethylene–polyvinyl alcohol production line, publicly announced by Guangxi Guangwei Chemical Co., Ltd. [6]. The project’s most notable feature is its use of abundant local biomass resources such as sugarcane and tuber crops in Guangxi as raw materials, offering advantages including low energy consumption, low production costs, environmental friendliness, and high product quality.

The polymerization activity of VAC is defined as the time it takes for the initiator to produce bubbling—this duration is taken as the “activity” level, with longer times indicating higher levels of impurities in the VAC. The polymerization activity of VAC produced via the calcium carbide–acetylene process typically ranges from 11 to 13 minutes, whereas the polymerization activity of VAC produced via the bio‑ethylene route is only 9 to 10 minutes. This difference stems from the fact that VAC manufactured using the bio‑ethylene process boasts a purity exceeding 99.9%, while the acetylene process yields VAC with a purity of just 99%. This process successfully shifted the production pathway for polyvinyl alcohol from coal chemistry to biomass chemistry, representing the pinnacle of technological advancement in the global polyvinyl alcohol industry. It has opened up new avenues for biomass energy utilization in China and freed polyvinyl alcohol production from reliance on fossil fuel industries such as petroleum and coal [7]. Moreover, Guangxi is located in the South Asian subtropical zone, characterized by abundant water resources, long summer seasons, distinct wet and dry seasons, and a frost‑free climate throughout the year—conditions particularly favorable for the growth of crops like cassava and sugarcane. Known as the “Kingdom of Biomass Energy,” Guangxi ranks first in the nation in terms of sugarcane output, accounting for more than 60% of the national total; its cassava cultivation area also leads the country, contributing roughly 70% of the national yield. These得天独厚 (inherently advantageous) biomass resources provide an ideal foundation for the widespread adoption of the bio‑ethylene route, making the use of bio‑ethylene to produce VAC in Guangxi doubly significant—both environmentally beneficial and inherently renewable.

X. Development Trends in the Future Polyvinyl Alcohol Industry

On the one hand, it is evolving toward high‑polymerization‑degree (high‑viscosity) and highly refined products, demonstrating excellent performance in areas such as high‑grade adhesives, high‑strength, high‑modulus fibers, PVB, PVA films, cellulose foam, sand stabilization agents, and cement admixtures. On the other hand, it is shifting toward low‑polymerization‑degree, partially or slightly hydrolyzed high‑value specialty products, primarily used in applications requiring specific properties, including water‑soluble adhesives, water‑soluble fibers, polymerization aids, and fields such as medical and electronic industries. With the rapid growth in demand for high‑density, high‑grade textiles, safety glass for automobiles and construction, as well as in the electronics, medical, and pharmaceutical sectors, new PVA products like PVB films, PVA optical films, and biodegradable polyvinyl alcohol films are poised to unlock significant market potential.