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Features That Distinguish Polyurethane Grade 1,4-Butanediol

Views: 223     Author: Vickey     Publish Time: 2023-12-14      Origin: Site


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Features That Distinguish Polyurethane Grade 1,4-Butanediol

1,4-butanediol is a fluid diol intermediate that has a linear structure and reactive primary hydroxyl functionality. It is ideally suited for the formulation of polyurethanes that possess a good balance of hardness and low-temperature flexibility, as well as high strength, durability, and thermal stability.

Despite the fact that 1,4-BDO can be utilised in a variety of applications as a polymer intermediate, BDO is of utmost importance in the production of polyurethanes. Urethane-grade BDO is especially useful due to its low moisture content (with a moisture standard of less than 150 ppm) and extremely high purity (with a purity level exceeding 99.85 percent by gramme counts).

The purpose of this page is to provide an explanation of three essential qualities that distinguish urethane-grade BDO from other types of BDO. These properties include its role as a chain extender as well as its many applications.

The Function of 1,4-Butanediol As a Component of Polyurethane

The structure of the molecular backbone of a polyurethane has a considerable impact on the qualities of the polyurethane, and chain extenders are an important component in the transformation of polyurethanes into materials with improved mechanical properties.

In the field of polyurethanes, BDO is used as both an intermediate for polyester polyols and a urethane chain extender. Chain extenders, such as BDO, are considered to be difunctional reactants, whereas crosslinkers are considered to be reactants with higher functionality.

Additionally, the 1,4-BDO chain extender is the one that the majority of processors favor when it comes to MDI systems. In order to fulfil this function, BDO reacts with MDI or MDI-based prepolymers as well as H12 MDI systems in order to produce the "hard segment" domains of polyurethanes. 1,4-butanediol produces crystalline urethane domains, which enables quick microphase separation and robust elastomeric networks.

In thermoplastic polyurethane (TPU) mixtures, BDO-MDI domains that are not cross-linked can melt and flow at high temperatures. This lets thermoplastic processing happen. Compositions of tough elastomeric materials are formed when the related networks are reformed after being cooled.

Additionally, polyester polyols can be made with the use of 1,4-butanediol as an intermediate. When it comes to polyurethane elastomers, the "soft segment" domains are created with the assistance of BDO polyester polyols like polyol.

Formulators are able to generate polyurethanes that have high mechanical properties throughout a wide temperature range by utilising BDO polyester polyol. Good abrasion resistance, resistance to cuts and chips, exceptional resistance to oil, grease, and chemicals, and weatherability are all characteristics of these polyurethanes.

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The 1,4-Butanediol's Performance as a Chain Extender

It is important to understand the odd-even effect in polyurethane intermediates in order to understand why 1,4-butanediol is used so often as a chain extender.

The first condition for the diol urethane intermediate to work is that it must be linear. The second condition is that it should have an even number of carbon atoms, which means that there should be an even number of CH2 groups in the repeating chain.

The overall performance of the elastomers made in this way is improved by the molecular-level chain packing of the different hard and soft parts of polyurethanes. It has been observed that there is an odd-even carbon number effect for polyester polyols and diol chain extenders.

For example, adipate polyester polyols based on diols with an even number of carbon atoms (EG-2, BDO-4, and HDO-6) have higher melting points, glass transition temperatures, and overall performance properties than similar systems based on diols with an odd number of carbon atoms (PrDO-3 and PeDO-5).

The MDI-BDO hard segments of a polyurethane exhibit a particularly remarkable degree of crystallinity and melt enthalpy. This is a really remarkable feature.

It is believed that the crystal packing of the hard segment and the hydrogen bonding that occurs between neighbouring urethane molecules are responsible for the odd-even effect.

It has been demonstrated through modelling that even-number chain extenders result in better alignment of the molecular chains, and using chain extenders such as BDO makes it easier for hydrogen bonds to form between chains. It is because of this that the advantageous phase separation between the hard and soft polymeric segments is achieved. In fact, numerous studies have shown that the qualities of a polyurethane are highly dependent on the degree of phase separation that is present and how well it is performed.

Despite the fact that ethylene glycol (EG) is also a diol chain extender with an even carbon number, it is not a suitable substitute for basic diol (BDO).

One problem with EG is that it doesn't mix well with many polyols, which can cause processing and performance issues. Another problem is that EG is polar, which makes it less resistant to hydrolysis.

In addition, EG is an excellent chain extender and polyester intermediate, which enables the production of polyurethanes that have favourable mechanical properties.


The Conditions of Processing 1,4-Butanediol Chain Extensions

At room temperature, 1,4-butanediol can be used as a chain extender in MDI and aliphatic diisocyanate systems. This is because it is a liquid diol.

The processing temperature and the system's level of catalyst loading both have an impact on the pot life of diol/MDI systems. A pot life of ten to twenty minutes at seventy degrees Celsius is possible for uncatalyzed systems; however, the pot life will be drastically reduced if the processing is carried out at higher temperatures or if catalysts are used. When trying to speed up the reaction rate of the diol with the isocyanate, it is usual practice to make use of catalysts made of tin and titanate.

In addition, BDO freezes at a temperature of 20 degrees Celsius (68 degrees Fahrenheit). Therefore, it is essential to keep BDO at a temperature that is higher than the freezing point in order to prevent crystallisation in the equipment lines and phase separation in a B-side pharmaceutical formulation.

In addition, BDO is hygroscopic, which means that it must be maintained in an inert atmosphere in order to prevent the absorption of moisture. Urethane-grade BDO is able to provide processors with excellent control of stoichiometry because of its low moisture content. This is accomplished by preventing the reaction of water with isocyanates and the simultaneous emission of carbon dioxide gas bubbles while doing so.

Applications of 1,4-Butanediol

Since it is a versatile molecule, 1,4-butanediol (1,4-BD) has multiple applications in a variety of industries, including the following:

1.Industrial solvent

One of the most common applications for 1,4-butanediol is as a solvent in the manufacturing of plastics, such as polyurethane and other types of polymers. In addition to this, it is used as a solvent in the production of industrial coatings and cleansers.


2.Chemical intermediate

In the process of manufacturing a number of chemicals, including tetrahydrofuran (THF), γ-butyrolactone (GBL), and polybutylene terephthalate (PBT), it plays the role of a chemical intermediary. These compounds are necessary for the production of plastics, resins, and elastic fibres by the industrial industry.

3.Polymer production

The manufacturing of polyurethanes, which are extensively used in the creation of flexible and rigid foams, fibres, and elastomers, is made possible by the indispensable contribution of 1,4-butanediol.

4.Personal care products

As a result of the humectant qualities that it possesses, 1,4-butanediol is used in the manufacturing of personal care goods such as moisturisers, hair care products, and cosmetics.

5.Medical and pharmaceutical

One of the most common uses for 1,4-butanediol is as a precursor in the production of a number of different drugs in the pharmaceutical and medical industries. It also performs the function of a solvent in the process of manufacturing pharmaceutical products.

6.Other uses

In addition to the applications that have been listed above, 1,4-butanediol is also used in the manufacturing of industrial cleansers, adhesives, and sealants of various kinds.

Despite the fact that 1,4-butanediol has a wide range of applications in the industrial sector, it is essential to understand how to handle it correctly because it can be hazardous if it is not handled in a suitable manner.

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