Classification of Polyimide

Since polycondensation polyimide has the disadvantages as mentioned above, in order to overcome these disadvantages, polymerisation polyimide has been developed. The main ones that have gained wide application are polybismaleimide and norbornene-based end-capped polyimides. Usually, these resins are low relative molecular mass polyimides with unsaturated groups at the ends, and then polymerised by unsaturated end groups when applied.
①Polybismaleimide
Polybismaleimide is made by polycondensation of maleic anhydride and aromatic diamine. Compared with polyimide, its performance is not bad, but the synthesis process is simple, easy post-processing, low cost, can be easily made into a variety of composite products. But the cured material is more brittle.
②Norbornene-based capped polyimide resin
One of the most important is developed by NASA Lewis Research Center, a class of PMR (for insitu polymerization of monomer reactants, monomer reactants in situ polymerization) type polyimide resins. RMR-type polyimide resins are aromatic tetracarboxylic acid dialkyl ester, aromatic diamine and 5-norbornene-2, 3-dicarboxylic acid monoalkyl ester, aromatic diamine and 5-norbornene-2, 3-dicarboxylic acid monoalkyl esters. 3-dicarboxylic acid monomers such as dialkyl esters of aromatic tetracarboxylic acids, aromatic diamines and monoalkyl esters of 5-norbornene-2,3-dicarboxylic acid are dissolved in a tasted alcohol (e.g., methanol or ethanol) to produce a solution that can be used directly to impregnate fibres. Polyimide is a molecular structure containing imide-based chain links of aromatic heterocyclic polymer compounds, the English name Polyimide (referred to as PI), can be divided into benzene-type PI, soluble PI, polyamide-imide (PAI) and polyetherimide (PEI) four categories.

Extended Reading:

PC-37 – Amine Catalysts (newtopchem.com)

Dabco foaming catalyst/polyurethane foaming catalyst NE300 – Amine Catalysts (newtopchem.com)

DABCO EG/PC CAT TD 33EG/Niax A-533 – Amine Catalysts (newtopchem.com)

FASCAT4100 catalyst – Amine Catalysts (newtopchem.com)

T120 1185-81-5 di(dodecylthio) dibutyltin – Amine Catalysts (newtopchem.com)

DABCO 1027/foaming retarder – Amine Catalysts (newtopchem.com)

DBU – Amine Catalysts (newtopchem.com)

bismuth neodecanoate/CAS 251-964-6 – Amine Catalysts (newtopchem.com)

stannous neodecanoate catalysts – Amine Catalysts (newtopchem.com)

polyurethane tertiary amine catalyst/Dabco 2039 catalyst – Amine Catalysts (newtopchem.com)

Does using polyimide resin powder affect the air?

Polyimide resin powder in the sintering curing process, may produce some emissions, mainly including: 1. formaldehyde: due to the polyimide resin powder contains formaldehyde groups, so in the sintering curing, will release a small amount of formaldehyde exhaust. 2. ammonia: polyimide resin powder in the sintering curing process, may release a small amount of ammonia exhaust. 3. carbon dioxide: in the high temperature, polyimide resin powder will decomposition Carbon dioxide exhaust gas is generated. Precautions: 1. Temperature and time should be strictly controlled during the sintering and curing process to avoid generating excessive exhaust gases. 2. Necessary exhaust and protective measures should be taken to ensure the safety of the working environment. 3. Hazards: 1. Formaldehyde is a hazardous substance and is harmful to human health. Long-term exposure to formaldehyde may lead to respiratory diseases, cancer and other illnesses. 2. Ammonia and carbon dioxide are also harmful gases. Long-term exposure to these gases may cause headaches, coughing, shortness of breath and other uncomfortable symptoms. At the same time, the emission of these gases may also pollute the atmosphere and affect air quality.
During the sintering and curing process of polyimide resin powder, the main exhaust gases produced are carbon monoxide, carbon dioxide, nitrogen oxides, sulphur oxides, nitrates, organic gases and water vapour. Among them, carbon monoxide and carbon dioxide are mainly emitted by fuel combustion; nitrogen oxides and sulphur oxides are mainly generated due to the organic substances contained in the surface materials during sintering; nitrates are mainly generated due to the nitrides contained in the structural materials; organic gases are mainly generated due to the organic substances contained in the surface materials during sintering; and water vapour is mainly generated due to the water contained in the structural materials.

Extended Reading:

PC-37 – Amine Catalysts (newtopchem.com)

Dabco foaming catalyst/polyurethane foaming catalyst NE300 – Amine Catalysts (newtopchem.com)

DABCO EG/PC CAT TD 33EG/Niax A-533 – Amine Catalysts (newtopchem.com)

FASCAT4100 catalyst – Amine Catalysts (newtopchem.com)

T120 1185-81-5 di(dodecylthio) dibutyltin – Amine Catalysts (newtopchem.com)

DABCO 1027/foaming retarder – Amine Catalysts (newtopchem.com)

DBU – Amine Catalysts (newtopchem.com)

bismuth neodecanoate/CAS 251-964-6 – Amine Catalysts (newtopchem.com)

stannous neodecanoate catalysts – Amine Catalysts (newtopchem.com)

polyurethane tertiary amine catalyst/Dabco 2039 catalyst – Amine Catalysts (newtopchem.com)

Polyimide for special engineering plastics

Polyimide is the molecular structure contains an aromatic heterocyclic polymer compounds of polyimide-based chain links, the English name Polyimide (PI for short), can be divided into benzene-type PI, soluble PI, polyamide-imide (PAI) and polyetherimide (PEI) four categories.
PI is currently one of the best varieties of engineering plastics heat resistance, some varieties can withstand long-term 290 ℃ high temperature for a short period of time to withstand a high temperature of 490 ℃, but also very low temperature, such as in the -269 ℃ liquid helium will not be brittle. In addition, mechanical properties, fatigue resistance, flame retardant, dimensional stability, electrical properties are good, molding shrinkage is small, resistant to oil, general acids and organic solvents, not alkali resistance, excellent friction resistance, abrasion properties. And PI is non-toxic, can be used to manufacture tableware and medical equipment, and withstand thousands of times disinfection.
PI moulding methods include compression moulding, impregnation, injection moulding, extrusion, die-casting, coating, casting, laminating, foaming and transfer moulding. PI has applications in aerospace, automotive, electronic and electrical appliances, industrial machinery, etc. It can be used as engine combustion system parts, jet engine components, compressor and generator parts, fasteners, spline joints and electronic contacts, as well as automotive engine parts, bearings, piston bushings, timing gears, printed wiring boards, insulating materials, heat-resistant cables, terminal blocks, sockets in the electronics industry, high temperature resistant self-lubricating bearings, and sockets in the machinery industry. High-temperature self-lubricating bearings, compressor blades and piston machine, sealing rings, equipment heat shield, thrust washers, bushings, etc..
Polyetherimide has excellent mechanical properties, electrical insulation properties, irradiation resistance, high and low temperature resistance and abrasion resistance, self-extinguishing, good melt flow, the shrinkage rate of the moulding is only 0.5 % ~ 0.7 %. PEI can be injection and extrusion moulding, post-processing is easier, can be adhesive or a variety of welding method and other materials, PEI in the electronics and electrical appliances, aerospace, automotive, medical equipment and other industries have been widely used. GE is the world’s largest producer of PEI, there are some engineering plastics modification company to provide PEI alloys and other modified products. The trend of development is the introduction of p-phenylenediamine structure or with other special engineering plastics alloy to improve its heat resistance; or with PC, PA and other engineering plastics alloy to improve its mechanical strength.
Polyamide-imide strength is currently the highest in the non-reinforced plastics, the colour of the material tensile strength of 190MPa, bending strength of 250MPa. 1.8MPa load heat deflection temperature of 274 ℃. PAI has good ablation resistance and high temperature, high frequency under the electromagnetic properties of metals and other materials have good adhesive properties. Mainly used for gears, rollers, bearings and copier separation claws, etc., but also for aircraft ablative materials, magnetic permeability and structural materials.PAI by Amoco company was the first to develop a successful and commercialised, in addition to Amoco, Japan’s Toray can also provide moulding plastics. Its development direction is to enhance the modification, and alloy with other plastics.

Extended Reading:

PC-37 – Amine Catalysts (newtopchem.com)

Dabco foaming catalyst/polyurethane foaming catalyst NE300 – Amine Catalysts (newtopchem.com)

DABCO EG/PC CAT TD 33EG/Niax A-533 – Amine Catalysts (newtopchem.com)

FASCAT4100 catalyst – Amine Catalysts (newtopchem.com)

T120 1185-81-5 di(dodecylthio) dibutyltin – Amine Catalysts (newtopchem.com)

DABCO 1027/foaming retarder – Amine Catalysts (newtopchem.com)

DBU – Amine Catalysts (newtopchem.com)

bismuth neodecanoate/CAS 251-964-6 – Amine Catalysts (newtopchem.com)

stannous neodecanoate catalysts – Amine Catalysts (newtopchem.com)

polyurethane tertiary amine catalyst/Dabco 2039 catalyst – Amine Catalysts (newtopchem.com)

Synthesis of polyaniline

There are many synthesis methods for polyaniline, but the commonly used synthesis methods are two categories: chemical synthesis and electrochemical synthesis.
(1) Chemical synthesis method Chemical synthesis method is to use oxidant as initiator to make aniline monomer oxidative polymerisation in acidic medium, the specific implementation methods are as follows.
Chemical oxidative polymerisation The chemical oxidative polymerisation of polyaniline is to make the aniline monomer oxidatively polymerised by oxidising agent under acidic condition. Protonic acid is an important factor affecting the oxidative polymerisation of aniline, which mainly plays two roles: to provide the pH value of the reaction medium and the form of dopant into the polyaniline skeleton to give it a certain conductivity. Polymerisation is carried out simultaneously with on-site doping, and polymerisation and doping are completed simultaneously. Commonly used oxidising agents are: hydrogen peroxide, dichromate, persulfate, etc. Its synthesis reaction is mainly affected by the type and concentration of protonated acid, the type and concentration of oxidant, the concentration of monomer and the reaction temperature, reaction time and other factors. The advantages of chemical oxidation polymerisation are that it can produce polyaniline in large quantities, with low investment in equipment, simple process, suitable for industrial production, and it is the most commonly used synthesis method at present.
Emulsion polymerisation Emulsion polymerisation is a method of adding an initiator into an acidic emulsion system containing aniline and its derivatives. Emulsion polymerisation has the following advantages: environmentally friendly and low-cost water is used as the heat carrier, and the product does not need to be precipitated and separated to remove the solvent; the synthesised polyaniline has a higher molecular weight and solubility; if large molecules of sulfonic acid are used as the surfactant, doping can be completed in a single step to increase the conductivity of the conductive polyaniline; polyaniline can be made into an emulsion that is directly usable, so that the subsequent processing does not need to use expensive or toxic organic solvents, simplifying the process and making it easier to produce polyaniline. Organic solvents, simplify the process, reduce costs, but also to overcome the shortcomings of the traditional method of synthesis of polyaniline insoluble and non-melting.
Microemulsion polymerisation Microemulsion polymerisation is developed on the basis of emulsion method. The polymerisation system consists of water, aniline, surfactant and co-surfactant. The microemulsion dispersed phase droplet size (10~100 nm) is smaller than that of normal emulsion (10~200 nm), which is very favourable for the synthesis of nanoscale polyaniline. The nano-polyaniline particles may not only solve the defects of difficult processing and moulding, but also combine the polymer electrical conductivity and the unique physicochemical properties of nano-particles, therefore, the microemulsion method has become a research hotspot in the field since the first report of synthesizing polyaniline particles with the smallest particle size of 5 nm using this method in 1997. Currently, conventional O/W microemulsions are used for the synthesis of polyaniline nanoparticles, and the commonly used surfactants are DBSA, sodium dodecyl sulfate, etc., with particle sizes of about 10-40 nm. reversed-phase microemulsions (W/O) are used for the preparation of polyaniline nanoparticles, which can obtain smaller particle sizes (<10 nm), and a more uniform distribution of the particle sizes. This is due to the fact that fewer aniline monomers are dissolved in the aqueous core of the reversed-phase microemulsion than in the oil core of the conventional microemulsion.
Dispersion polymerisation The aniline dispersion polymerisation system is generally composed of aniline monomer, water, dispersant, stabiliser and initiator. The medium before the reaction is a homogeneous system, but the generated polyaniline is insoluble in the medium, when it reaches the critical chain length from the medium precipitation, with the help of stabilizers suspended in the medium, the formation of a stable dispersion system similar to the polymer emulsion. This method is currently used in the synthesis of polyaniline research is far less mature than the above three implementation methods, less research.
Mature, less research.
(2) Electrochemical synthesis method The electrochemical polymerisation of polyaniline includes the following methods: constant potential method, constant current method, dynamic potential scanning method and pulse polarisation method. Generally An is polymerised in acidic solution at the anode. Electrochemical synthesis of polyaniline is the oxidative polymerisation of An at the anode in an electrolyte solution containing An, resulting in a polyaniline film adhering to the electrode surface or a polyaniline powder deposited on the electrode surface.Diaz et al. prepared polyaniline films by electrochemical methods.
At present, PANI electrochromic films are mainly prepared by electrochemical methods, but there are several drawbacks in the preparation of PANI electrochromic films by electrochemical methods, such as: the inability to prepare electrochromic films on a large scale; the poor mechanical properties of the PANI film; and the poor adhesion of the PANI film to the conductive glass substrate.

Extended Reading:

PC-37 – Amine Catalysts (newtopchem.com)

Dabco foaming catalyst/polyurethane foaming catalyst NE300 – Amine Catalysts (newtopchem.com)

DABCO EG/PC CAT TD 33EG/Niax A-533 – Amine Catalysts (newtopchem.com)

FASCAT4100 catalyst – Amine Catalysts (newtopchem.com)

T120 1185-81-5 di(dodecylthio) dibutyltin – Amine Catalysts (newtopchem.com)

DABCO 1027/foaming retarder – Amine Catalysts (newtopchem.com)

DBU – Amine Catalysts (newtopchem.com)

bismuth neodecanoate/CAS 251-964-6 – Amine Catalysts (newtopchem.com)

stannous neodecanoate catalysts – Amine Catalysts (newtopchem.com)

polyurethane tertiary amine catalyst/Dabco 2039 catalyst – Amine Catalysts (newtopchem.com)

Method for preparing calcium propionate from calcium carbonate

Image keywords Image keywords

Calcium propionate is white crystalline particles or crystalline powder. It is odorless or slightly smells of propionic acid, hygroscopic, easily soluble in water, and insoluble in alcohol. Calcium propionate is a newer food antifungal agent. It is the calcium salt of the acidic antifungal agent propionic acid. Under acidic conditions, it produces free propionic acid, which is weaker than sorbic acid and stronger than acetic acid. It has antibacterial effects and is effective against Aspergillus niger and Aspergillus niger. Aerophilic Bacillus has inhibitory effect. Calcium propionate is produced by reacting propionic acid with calcium hydroxide or calcium carbonate. In industry, calcium hydroxide is generally used as raw material. Calcium hydroxide is adjusted into a suspension in a reaction pot, propionic acid is added to react, the end point pH is 7~8, and the finished product is obtained after filtration and drying.

The method of preparing calcium propionate from calcium carbonate is as follows:

First, the raw material calcium carbonate is made into a water suspension, and the water used must be refined and purified. Remove impurities such as heavy metal magnesium. Put the CaCO3 aqueous suspension quantitatively into the neutralization reaction kettle, keep the temperature inside the kettle at 60-80°C, and add propionic acid while stirring. The neutralization reaction lasts for 2-3 hours. At this time, a large amount of CO2 gas escapes. Discharge through the condenser vent pipe. By adjusting the external heating temperature, adding acid and stirring speed, the reaction can reach optimal conditions. The pH value at the end of the reaction should be controlled at 7 to 8. This reaction is a reversible reaction. The CO2 gas should be discharged in time to better control the end of the reaction. . The neutralized aqueous solution is vacuum filtered, and the filtrate obtained is concentrated in an evaporator, and then placed in a crystallization tank for slow cooling and crystallization at normal temperature and pressure. The mother liquor can be returned to the evaporator and used 2 to 3 times before discarding. The separated solid is dried into small particles, crushed, measured, and packaged to obtain the finished product of calcium propionate.
amine catalyst Dabco 8154 – BDMAEE

2-ethylhexanoic-acid-potassium-CAS-3164-85-0-Dabco-K-15.pdf (bdmaee.net)

Dabco BL-11 catalyst CAS3033-62-3 Evonik Germany – BDMAEE

Polycat 9 catalyst CAS33329-35-6 Evonik Germany.pdf – BDMAEE

Dabco NE300 catalyst CAS10861-07-1 Evonik Germany.pdf (bdmaee.net)

Dabco 1027 Catalyst CAS100515-55-5 Evonik Germany – BDMAEE

Fomrez UL-28 Catalyst Dimethyltin Dioctadecanoate Momentive – BDMAEE

Polycat 77 catalyst CAS3855-32-1 Evonik Germany.pdf (bdmaee.net)

Polycat 41 catalyst CAS10294-43-5 Evonik Germany – BDMAEE

Polycat DBU catalyst CAS6674-22-2 Evonik Germany – BDMAEE

Low Odor Polyurethane Rigid Foam Catalysts: Enhancing Indoor Air Quality and Comfort in Insulation Applications

Polyurethane (PU) rigid foam is a widely used insulation material, known for its excellent thermal performance and energy efficiency. However, the production and use of traditional PU rigid foam can result in the emission of volatile organic compounds (VOCs) and unpleasant odors, which can negatively impact indoor air quality and human comfort. To address these concerns, the development of low odor polyurethane rigid foam catalysts has emerged as a promising solution. This article will discuss the importance of low odor PU rigid foam catalysts, their benefits, and their role in promoting healthier and more comfortable indoor environments.

 

The Need for Low Odor Polyurethane Rigid Foam Catalysts
Traditional PU rigid foam insulation is produced by reacting polyols and isocyanates in the presence of catalysts, blowing agents, and other additives. During this process, residual chemicals and byproducts can emit VOCs and unpleasant odors, which can persist even after the foam has been installed. Exposure to these emissions can cause various health issues, such as eye, nose, and throat irritation, headaches, and respiratory problems. Moreover, the presence of unpleasant odors can negatively affect human comfort and overall satisfaction with the insulation material.

 

To mitigate these issues, the development of low odor PU rigid foam catalysts has become a key focus in the insulation industry. These catalysts are designed to minimize the emission of VOCs and odors during the production and use of PU rigid foam, ultimately improving indoor air quality and human comfort.

 

Benefits of Low Odor Polyurethane Rigid Foam Catalysts
Improved Indoor Air Quality: Low odor PU rigid foam catalysts significantly reduce the emission of VOCs and unpleasant odors, contributing to healthier and cleaner indoor environments. This is particularly important in sensitive applications, such as schools, hospitals, and residential buildings, where maintaining good indoor air quality is crucial for occupant health and well-being.
Enhanced Comfort: By minimizing unpleasant odors, low odor PU rigid foam catalysts help create more comfortable living and working spaces. This can lead to increased occupant satisfaction and improved overall perception of the insulation material.

Compliance with Regulations and Standards: As concerns over indoor air quality and VOC emissions continue to grow, various regulations and standards have been established to limit the emission of harmful substances from building materials. The use of low odor PU rigid foam catalysts helps manufacturers comply with these requirements, ensuring the production of safer and more environmentally friendly insulation products.
Market Differentiation: By offering low odor PU rigid foam insulation, manufacturers can differentiate their products in the competitive insulation market. This can lead to increased demand and customer loyalty, as consumers become more aware of the importance of indoor air quality and odor control.
Examples of Low Odor Polyurethane Rigid Foam Catalysts
Several low odor PU rigid foam catalysts have been developed in recent years, each with its unique formulation and performance characteristics. Some examples include:
Amine Catalysts: Traditional amine catalysts, such as triethylenediamine (TEDA) and dimethylcyclohexylamine (DMCHA), can be replaced with low odor alternatives, such as N,N-dimethylcyclohexylamine (DMCA) and 1-methylcyclohexylamine (MCHA). These catalysts offer similar performance to their traditional counterparts but with significantly reduced odor and VOC emissions.
Metal Catalysts: Metal-based catalysts, such as tin and bismuth octoates, can also be formulated to have low odor properties. These catalysts are often used in combination with amine catalysts to achieve optimal curing and foam performance while minimizing odor and VOC emissions.
Glycerin-Based Catalysts: Glycerin-based catalysts, such as glycerin-derived polyols, can be used as a replacement for traditional polyols in PU rigid foam production. These catalysts offer reduced odor and VOC emissions, as well as improved sustainability due to their renewable origin.
In conclusion, low odor polyurethane rigid foam catalysts play a crucial role in addressing concerns related to indoor air quality and human comfort in insulation applications. By minimizing the emission of VOCs and unpleasant odors, these catalysts contribute to healthier and more comfortable indoor environments, while also helping manufacturers comply with regulations and differentiate their products in the market. As the demand for safer and more sustainable insulation materials continues to grow, the development and adoption of low odor PU rigid foam catalysts are expected to gain further momentum in the insulation industry.
Recommended Related Reading:

TEDA-L25B polyurethane tertiary amine catalyst Tosoh

Toyocat DAEM Catalyst Tosoh

Toyocat DMCH Hard bubble catalyst for tertiary amine Tosoh

Toyocat DMI gel catalyst Tosoh

Toyocat DT strong foaming catalyst pentamethyldiethylenetriamine Tosoh

Toyocat ET catalyst Tosoh

Toyocat ETS Foaming catalyst Tosoh

https://www.bdmaee.net/toyocat-mr-gel-balanced-catalyst-tetramethylhexamethylenediamine-tosoh/
https://www.bdmaee.net/toyocat-np-catalyst-tosoh/

Silicone Curing Catalysts: Enhancing the Performance and Versatility of Silicone Materials

Silicone materials are widely used in various industries, including automotive, construction, electronics, and personal care, due to their unique properties such as thermal stability, chemical resistance, and flexibility. The curing process of silicone materials plays a crucial role in determining their final properties and performance. Silicone curing catalysts are essential components in this process, as they control the rate and extent of cross-linking reactions, ultimately influencing the characteristics of the cured silicone product. This article will discuss the role of silicone curing catalysts, their types, and their impact on the properties and applications of silicone materials.
Role of Silicone Curing Catalysts
Silicone curing catalysts are substances that initiate or accelerate the cross-linking reactions between silicone polymers, leading to the formation of a three-dimensional network. This network provides the cured silicone material with its desired properties, such as elasticity, durability, and resistance to heat and chemicals. The choice of curing catalyst significantly affects the curing rate, the degree of cross-linking, and the final properties of the silicone product.
Types of Silicone Curing Catalysts
There are several types of silicone curing catalysts, each with its unique characteristics and applications. The most common catalysts include:
Platinum-based catalysts: Platinum-based catalysts, such as chloroplatinic acid and platinum divinyltetramethyldisiloxane complex, are widely used in addition-cure silicone systems. These catalysts promote the cross-linking reaction between silicone polymers containing vinyl and hydride groups, resulting in a highly stable and durable network. Platinum-based catalysts are known for their high reactivity, low toxicity, and minimal impact on the final product’s color and odor.
Condensation catalysts: Condensation catalysts are used in condensation-cure silicone systems, where they promote the reaction between silanol groups on silicone polymers, leading to the formation of siloxane bonds and the release of a byproduct, usually water or alcohol. Common condensation catalysts include metal salts, such as tin octoate and dibutyltin dilaurate, and organic acids, such as acetic acid and oxalic acid. Condensation catalysts are generally less expensive than platinum-based catalysts but may have a more significant impact on the final product’s color and odor.
Peroxide catalysts: Peroxide catalysts, such as benzoyl peroxide and dicumyl peroxide, are used in free-radical cure silicone systems. These catalysts generate free radicals when heated, initiating the cross-linking reaction between silicone polymers. Peroxide catalysts are typically used in high-temperature applications, such as mold-making and encapsulation, where rapid curing and high thermal stability are required.
Impact of Silicone Curing Catalysts on Properties and Applications
The choice of silicone curing catalyst significantly influences the properties and performance of the cured silicone material. For example, platinum-based catalysts are often preferred for applications requiring high stability, low toxicity, and minimal color change, such as medical devices, food-grade silicone, and electronic components. On the other hand, condensation catalysts are commonly used in applications where cost is a primary concern, such as sealants, adhesives, and coatings.
In addition to affecting the final properties of the silicone material, curing catalysts also play a crucial role in determining the processing conditions and curing time. For instance, peroxide catalysts enable rapid curing at elevated temperatures, making them suitable for high-throughput manufacturing processes. In contrast, platinum-based and condensation catalysts typically require longer curing times, which may be more appropriate for applications where precise control over the curing process is necessary.
In conclusion, silicone curing catalysts are essential components in the production of silicone materials, as they control the cross-linking reactions that determine the final properties and performance of the cured product. The choice of curing catalyst depends on the specific application requirements, with platinum-based, condensation, and peroxide catalysts offering unique advantages and trade-offs. As the demand for silicone materials continues to grow across various industries, the development and optimization of silicone curing catalysts will remain a critical area of research and innovation.
Recommended Related Reading:
Dabco NE300 catalyst CAS10861-07-1 Evonik Germany.pdf (bdmaee.net)
Dabco 1027 Catalyst CAS100515-55-5 Evonik Germany – BDMAEE
Fomrez UL-28 Catalyst Dimethyltin Dioctadecanoate Momentive – BDMAEE
Polycat 77 catalyst CAS3855-32-1 Evonik Germany.pdf (bdmaee.net)
Polycat 41 catalyst CAS10294-43-5 Evonik Germany – BDMAEE
Polycat DBU catalyst CAS6674-22-2 Evonik Germany – BDMAEE
NT CAT U28
NT CAT U26
NT CAT K-15
NT CAT D60

Rigid Polyurethane: Insulation Material of Choice for Energy Efficiency and Sustainability

Rigid polyurethane (PUR) foam is a versatile, lightweight, and high-performance insulation material used in various applications, including building and construction, refrigeration, and transportation. Known for its excellent thermal insulation properties, rigid polyurethane foam has become an essential component in energy-efficient and sustainable building designs. This article will discuss the properties, production, and applications of rigid polyurethane foam, highlighting its role in promoting energy efficiency and sustainability.
Properties of Rigid Polyurethane Foam
Rigid polyurethane foam is characterized by its closed-cell structure, which provides excellent thermal insulation, low air permeability, and high dimensional stability. The insulation properties of rigid PUR foam are primarily attributed to the presence of low-conductivity gas, such as air or carbon dioxide, within the cells. The closed-cell structure also prevents moisture infiltration, ensuring the foam’s long-term performance and resistance to mold and mildew growth.
The thermal conductivity of rigid polyurethane foam typically ranges from 0.018 to 0.025 W/mK, making it one of the most efficient insulation materials available. Additionally, rigid PUR foam exhibits excellent mechanical properties, such as high compressive strength and stiffness, which enable its use in load-bearing applications.
Production of Rigid Polyurethane Foam
Rigid polyurethane foam is produced through a reaction between polyols and isocyanates, in the presence of blowing agents, catalysts, and other additives. The reaction forms a polymer network, with the blowing agent responsible for creating the foam’s closed-cell structure.
Traditionally, hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) have been used as blowing agents in the production of rigid PUR foam. However, due to their high global warming potential (GWP) and ozone-depleting properties, there is a growing shift towards more environmentally friendly alternatives, such as hydrofoams and low-GWP blowing agents.
Applications of Rigid Polyurethane Foam
Rigid polyurethane foam is widely used in various applications, with building and construction being the most significant market segment. In buildings, rigid PUR foam is employed as insulation for roofs, walls, and floors, contributing to improved energy efficiency and indoor comfort. Its high thermal performance and space-saving characteristics make it an ideal choice for both new constructions and retrofit projects.
In addition to building insulation, rigid polyurethane foam is used in refrigeration applications, such as insulation for refrigerators, freezers, and cold storage facilities. The foam’s excellent thermal insulation properties help maintain consistent temperatures and reduce energy consumption in these applications.
Rigid PUR foam is also utilized in the transportation industry, where it serves as insulation for vehicles, ships, and aircraft. The lightweight nature of rigid polyurethane foam contributes to fuel savings and reduced greenhouse gas emissions in transportation applications.
Sustainability and Environmental Impact
Rigid polyurethane foam plays a crucial role in promoting energy efficiency and sustainability, thanks to its exceptional insulation properties. By reducing heating and cooling energy consumption in buildings, refrigeration, and transportation, rigid PUR foam contributes to lower greenhouse gas emissions and energy costs.
Moreover, the use of environmentally friendly blowing agents and recycling initiatives for polyurethane waste further enhance the sustainability of rigid PUR foam. Efforts are underway to develop bio-based polyols and other renewable raw materials for the production of rigid polyurethane foam, which could significantly reduce its carbon footprint and dependence on fossil fuels.
In conclusion, rigid polyurethane foam is a high-performance insulation material with a wide range of applications in building and construction, refrigeration, and transportation. Its excellent thermal insulation properties, combined with its lightweight and durable nature, make it an essential component in energy-efficient and sustainable building designs. As the industry continues to adopt more environmentally friendly production methods and materials, the sustainability of rigid polyurethane foam is set to improve further, solidifying its position as a key contributor to a greener future.
Recommended Related Reading:
https://www.bdmaee.net/toyocat-dmi-gel-catalyst-tosoh/
https://www.bdmaee.net/toyocat-dt-strong-foaming-catalyst-pentamethyldiethylenetriamine-tosoh/
https://www.bdmaee.net/toyocat-et-catalyst-tosoh/
https://www.bdmaee.net/toyocat-ets-foaming-catalyst-tosoh/
https://www.bdmaee.net/toyocat-mr-gel-balanced-catalyst-tetramethylhexamethylenediamine-tosoh/
https://www.bdmaee.net/toyocat-np-catalyst-tosoh/https://www.bdmaee.net/toyocat-pma-tertiary-amine-catalyst-tosoh/
https://www.bdmaee.net/toyocat-rx3-organic-amine-catalyst-tosoh/
https://www.bdmaee.net/toyocat-rx5-catalyst-trimethylhydroxyethyl-ethylenediamine-tosoh/
https://www.bdmaee.net/toyocat-te-tertiary-amine-catalyst-tosoh/
https://www.bdmaee.net/toyocat-trc-catalyst-tosoh/

PVC Heat Stabilizers: Enhancing the Thermal Stability and Performance of Polyvinyl Chloride

Polyvinyl chloride (PVC) is a widely used thermoplastic polymer, valued for its versatility, durability, and cost-effectiveness. However, PVC is susceptible to degradation when exposed to heat during processing or in high-temperature applications. This degradation can lead to discoloration, loss of mechanical properties, and the release of harmful hydrogen chloride gas. To overcome these challenges, PVC heat stabilizers are employed to enhance the thermal stability and performance of the polymer. This essay will discuss the role of PVC heat stabilizers, their types, and their impact on the properties of PVC products.
PVC heat stabilizers are additives that prevent or minimize the degradation of PVC during processing or in high-temperature applications. They work by either scavenging the hydrogen chloride (HCl) released during degradation or by promoting the formation of cross-links between PVC chains, which improves the polymer’s thermal stability. The choice of heat stabilizer depends on the specific PVC application, processing conditions, and desired product properties.
There are several types of PVC heat stabilizers, including metal soaps, organotin compounds, epoxy-based stabilizers, and mixed metal stabilizers.

 

Metal soaps: Metal soaps, such as calcium and zinc stearates, are the most commonly used PVC heat stabilizers. They act as HCl scavengers, reacting with the released HCl to form stable metal chlorides. Metal soaps are cost-effective and provide good thermal stability, but they may have limited performance in high-temperature applications or when exposed to moisture.
Organotin compounds: Organotin stabilizers, such as dibutyltin maleate and dibutyltin laurate, are highly effective in promoting the thermal stability of PVC. They work by both scavenging HCl and promoting cross-linking between PVC chains. Organotin stabilizers are particularly suitable for applications that require excellent transparency, electrical properties, and long-term heat resistance. However, their use is being phased out due to environmental and health concerns.
Epoxy-based stabilizers: Epoxy-based stabilizers, such as epoxy resins and epoxidized vegetable oils, are used in combination with metal soaps or other stabilizers to enhance the thermal stability of PVC. They work by reacting with the HCl released during degradation and forming cross-links between PVC chains. Epoxy-based stabilizers are particularly effective in improving the heat stability of PVC in high-temperature applications and in the presence of moisture.
Mixed metal stabilizers: Mixed metal stabilizers, such as calcium-zinc and barium-zinc systems, are a newer generation of PVC heat stabilizers. They offer several advantages over traditional stabilizers, including improved thermal stability, reduced environmental impact, and better performance in specific applications. For example, calcium-zinc stabilizers are widely used in PVC pipes, window profiles, and cable insulation due to their excellent long-term heat resistance and low extractability.
The choice of PVC heat stabilizer has a significant impact on the properties and performance of the final product. For instance, the type and concentration of stabilizer used can influence the polymer’s thermal stability, color, mechanical properties, and resistance to weathering. Therefore, it is crucial to carefully select and optimize the stabilizer system based on the specific requirements of the PVC application.
In addition to traditional heat stabilizers, there is ongoing research into developing new and advanced stabilizer systems for PVC. These efforts aim to improve the thermal stability and performance of PVC while addressing environmental and health concerns associated with conventional stabilizers. For example, researchers are exploring the use of bio-based stabilizers, such as vegetable oil-derived epoxies, and nanoparticle-based stabilizers, such as layered double hydroxides, to enhance the sustainability and performance of PVC products.
In conclusion, PVC heat stabilizers play a crucial role in enhancing the thermal stability and performance of polyvinyl chloride. By preventing or minimizing the degradation of PVC during processing or in high-temperature applications, these additives enable the production of durable and versatile PVC products. The choice of heat stabilizer depends on the specific application requirements, and ongoing research in the field holds promise for improving the performance and sustainability of PVC products.
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The effect of catalysts on foaming

Polyether, as the main raw material, reacts with isocyanate to form carbamate, which is the skeleton reaction of foam products. With the same functionality, the tensile strength, elongation and resilience of foam increase with the increase of molecular weight, while the reactivity of similar polyethers decreases; In the case of the same equivalent value (molecular weight/functionality), with the increase of functionality, the reaction will be relatively accelerated, and the crosslinking degree of the generated polyurethane will be increased, the hardness of foam will be increased, and the elongation will be decreased. The average energy switching off degree of polyols should be more than 2.5. If the average energy switching off degree is too low, the recovery of foam body after pressure is poor.
If the amount of polyether is large, it is equivalent to the reduction of other raw materials (TDI, water, catalyst, etc.), which is easy to cause cracking or collapse of foam products.
If the amount of polyether is small, the foam products are hard, the elasticity is reduced, and the hand feel is bad.
2. Foaming agent
Generally, when manufacturing polyurethane block foams with a density greater than 21, only water (chemical foaming agent) is used as the foaming agent, and low boiling compounds such as dichloromethane (MC) (physical foaming agent) are used as auxiliary foaming agents in low-density or ultra soft formulations.
The auxiliary foaming agent will reduce the density and hardness of foam. Because its gasification absorbs part of the reaction heat, it will slow down the curing, so the amount of catalyst needs to be increased. Due to the absorption of heat, the danger of burning the core is avoided.
The foaming ability can be reflected by the foaming index (the equivalent of water or water used in 100 parts of polyether): m – the amount of foaming agent used
Foam index IF=m (water)+m (F-11)/10+m (MC.)/9 (100% polyether)
Water, as a foaming agent, reacts with isocyanates to form urea bonds and releases a large amount of CO2 and heat, which is a chain growth reaction.
With more water, the density of foam decreases and the hardness increases. At the same time, the foam pillar becomes smaller and weaker, which reduces the bearing capacity and is easy to collapse and crack. The consumption of TDI increases, releases more heat, and is prone to heartburn. If the water content exceeds 5.0 parts, a physical foaming agent must be added to absorb some of the heat and avoid the occurrence of core burning.
With less water, the amount of catalyst used decreases correspondingly, but the density increases
3. Toluene diisocyanate
Generally, a mixture of TDI80/20, 2,4, and 2,6 isomers is used for soft foam. T100 can be prepared by cooling method, which is pure 2,4TDI.
TDI dosage=(8.68+m water x 9.67) x TDI index. The TDI index is generally 110-120.
When the isocyanate index increases within a certain range, the hardness of foam increases, but after reaching a certain point, the hardness no longer increases significantly, but the tear strength, tensile strength and elongation decrease. The foam forms large pores, the closed pores rise, the resilience decreases, the surface becomes sticky for a long time, and the curing time is long, leading to core burning.
Low isocyanate index will cause foam cracks, poor resilience, poor strength, large compression permanent deformation, and a sense of moisture on the surface.
4. Catalyst
Amine: Generally, A33 is used to promote the reaction between isocyanate and water, adjust foam density, bubble opening ratio, etc., mainly to promote foaming reaction.
Amine: foam products split, and foam has holes or blisters
Less amine: foam shrinks and closes pores, and the bottom thickness of the foam product is produced.
Tin: Generally used is stannous octanoate T-9; T-19 is a gel reaction catalyst with high catalytic activity, mainly promoting gel reaction, that is, late reaction.
Tin excess: fast gelation, increased viscosity, poor rebound, poor breathability, resulting in closed pores. If the dosage is properly increased, a good open cell foamed plastic with looseness can be obtained. Further increasing the dosage makes the foam gradually become compact, so that it shrinks and closes the pores.
Less tin: insufficient gel, resulting in splitting during the foaming process. There are cracks at the edges or top, and there are phenomena of detachment and burrs.
Reducing amine or increasing tin can increase the strength of the polymer bubble membrane wall when a large amount of gas occurs, thereby reducing hollow or cracking phenomena.
Whether polyurethane foam has an ideal open or closed cell structure mainly depends on whether the gel reaction rate and gas expansion rate are balanced during the formation of foam. This balance can be achieved by adjusting the type and amount of tertiary amine catalyst, foam stabilizer and other additives in the formula.
5. Foam stabilizer (silicone oil)
Foam stabilizer is a kind of surfactant, which can make polyurea disperse well in the foaming system, play the role of “physical cross-linking point”, and significantly improve the early viscosity of foam mixture to avoid foam cracking. On the one hand, it has the emulsification effect, which enhances the mutual solubility between the components of foam materials; on the other hand, the addition of organosilicon surfactant can reduce the surface tension r of the liquid, reduce the free energy required for gas dispersion, make the air dispersed in the raw materials easier to nucleate during the mixing process, help to produce small bubbles, adjust the size of foam pores, control the foam pore structure, and improve the foaming stability; Prevent the cell from collapsing and cracking, make the foam wall elastic, and control the foam pore size and uniformity. It stabilizes foam at the initial stage of foaming, prevents foam from coalescing at the middle stage of blasting, and connects the foam pores at the later stage of foaming. The more foaming agent and POP used, the greater the amount of silicone oil used.
More dosage: make the elasticity of foam wall increase in the later period, not crack, and the foam hole is thin. Causing closed pores.
Low dosage: the foam bursts, collapses after starting, and the pore size is large, which is easy to mix.
6. The influence of temperature
The foaming reaction of polyurethane accelerates with the increase of material temperature, which can cause the danger of core burning and fire in sensitive formulas. The temperature of polyol and isocyanate components is generally controlled to remain constant. When foaming, the foam density decreases and the material temperature increases accordingly. With the same formula, the same material temperature, the high temperature in summer and the accelerated reaction speed lead to the decrease of foam density and hardness, the increase of elongation and the increase of mechanical strength. In summer, the TDI index can be appropriately increased to correct the decrease in hardness.
7. The impact of air humidity
With the increase of humidity, the isocyanate based part in the foam reacts with the moisture in the air, resulting in a decrease in hardness. Therefore, the amount of TDI can be properly increased during foaming. When it is too large, it can cause the ripening temperature to be too high and cause heartburn.
8. The influence of atmospheric pressure
With the same formula, the density of foam products is small when foaming at high altitude. Note:
1. In the forming process of foam plastics, gel reaction and foaming reaction occur together, but there is competition among the reactions. Generally, the speed of foaming reaction is greater than that of gel reaction.
Gel reaction – carbamate formation reaction (reaction with – OH)
Foaming reaction – a reaction involving water to generate urea and produce bubbles
2. Nucleating agent – a substance that causes the formation of bubbles, such as fine solid particles or liquids in a system
Foam stabilizer or tiny bubbles dissolved in materials; Including air or nitrogen, carbon dioxide, foam stabilizer, carbon black and other fillers dissolved in polyols and isocyanates. But gas generates more bubbles in the material; The more stable and generated bubbles, the finer the pores.
The number of bubbles formed in the foaming system and the size of the bubbles in the foam plastic depend on the role of the external nucleating agent; There are many nucleating agents, many bubbles, and small pores.
When the temperature rises, the solubility of gas in the liquid decreases, resulting in more bubbles forming or causing the previous start to grow. Long milky white time is beneficial for the growth of large bubbles.
The opalescence time can be shortened by increasing the amount of catalyst. Because of the competitive reaction between gel reaction and bubble formation, microporous foam can be obtained.
3. Whether foam has an ideal open or closed cell structure mainly depends on whether the gel speed and gas expansion speed are balanced during the formation of foam. This balance can be achieved by adjusting the type and amount of tertiary amine catalyst, foam stabilizer and other additives in the formula.
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