Dimethylol ethylene urea
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Dimethylol ethyleneurea is an
organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The ...
derived from
formaldehyde Formaldehyde ( , ) (systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section F ...
and
urea Urea, also known as carbamide, is an organic compound with chemical formula . This amide has two amino groups (–) joined by a carbonyl functional group (–C(=O)–). It is thus the simplest amide of carbamic acid. Urea serves an important r ...
. It is a colourless solid that is used for treating
cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wall ...
-based heavy fabrics to inhibit wrinkle formation. Dimethylol ethylene urea (DMEU) bonds with the hydroxyl groups present in long cellulose chains and prevents the formation hydrogen bonding between the chains, the primary cause of wrinkling. This treatment produces permanently
wrinkle-resistant fabric Wrinkle-resistant or permanent press or durable press is a finishing method for textiles that avoids creases and wrinkles and provides a better appearance for the articles. Most cellulosic fabrics and blends of cellulosic rich fabrics tend to ...
s and is different from the effects achieved from using
fabric softener A fabric softener (American English) or fabric conditioner (British English) is a conditioner that is applied to laundry during the rinse cycle in a washing machine to reduce harshness in clothes that are dried in air after machine washing. In con ...
s. An additional names for DMEU includes 1,3-bis(hydroxymethyl)-tetrahydro-2-imidazolone.


Mechanism

Wrinkles form in cotton fabrics due to the free
hydroxyl group In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy g ...
s. Cotton is a form of cellulose chains linked to form firm three-dimensional structures that offer both tensile strength and flexibility due to their carbon-carbon and carbon-oxygen bond based backbone. Since cellulose is composed of glucose units, cyclic carbohydrate molecules, cellulose has free hydroxyl groups (-OH) projecting from each
monomer In chemistry, a monomer ( ; ''mono-'', "one" + '' -mer'', "part") is a molecule that can react together with other monomer molecules to form a larger polymer chain or three-dimensional network in a process called polymerization. Classification Mo ...
ic subunit. These hydroxyl groups tend form hydrogen-bonds to neighboring hydroxyl groups. When the fabric is stressed either by heat or pressure, the original hydrogen bonds in the cotton fabric break and reform with nearby atoms at random. This re-forming of the hydrogen bonds, known as cross linking, is the reason for wrinkles, or creases, in the fabric. DMEU works to prevent these wrinkles by covalently bonding to two free hydroxyl groups in the fabric through a dehydration reaction that is not as easily broken as the hydrogen bond before treatment. As seen in the figure, this formation of a C-O bond through a dehydration reaction (loss of water) allows the fabric to be bleached and heated to reasonable temperatures without fear of breaking the C-O bonds formed. DMEU is applied industrially to the fabric after all the creases desired for design are in place. The fabric is heated and a DMEU resin is slathered on to the fabric. Depending on the procedure, the residue may contain metal catalysts or acid catalysts to help with the reaction. The utilization of DMEU in conjunction with a small concentration of tetraethoxysilane (TEOS) helps to improve the tensile strength of the treated material and decreases the yellowing of the material


Production

The production of DMEU is through the condensation of formaldehyde with ethylene urea: :2CH2O + (C2H4N2H2)CO → (C2H2N2(CH2OH)2)CO The reaction proceeds around but this temperature can be brought down to around in the presence of an acid
catalyst Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...
. Ethylene urea, sodium hydroxide, and paraformaldehyde are often dissolved in methanol during the synthesis of DMEU. :


History

Before the development of DMEU, formaldehyde and its derivatives were used as anti-wrinkle agents.. After contact with
chlorine bleach Bleach is the generic name for any chemical product that is used industrially or domestically to remove color (whitening) from a fabric or fiber or to clean or to remove stains in a process called bleaching. It often refers specifically, to ...
es at high temperatures, however, the treated fabric released hydrochloric acid, which degraded the fabric. Additionally, formaldehyde evaporates easily and is pungent. The search for stabler alternatives to formaldehyde led to dimethylol formaldehyde derivatives such as DMEU. The five member ring structure of DMEU, a 2-imidazolidone, resists attack by chlorine during bleaching. As an additional advantage, DMEU can be used to treat fabrics at relatively mild conditions and is odorless. The use of DMEU on cotton was patented by Rohm and Haas Co. in 1941. As suitable as DMEU was as an anti-wrinkle agent, it decreases dramatically the tensile strength of the fabric. Because DMEU inhibited new hydrogen bond formation, it also hindered the spreadability of cotton fibers under pressure. This problem regarding the loss of tensile strength is common amongst
cotton Cotton is a soft, fluffy staple fiber that grows in a boll, or protective case, around the seeds of the cotton plants of the genus ''Gossypium'' in the mallow family Malvaceae. The fiber is almost pure cellulose, and can contain minor perce ...
treatments. Another common problem from treatment of DMEU is the yellowing of the treated fabric, because of the acidic conditions with high amounts of heat. Currently, DMEU is used along with other formaldehyde urea derivatives for cotton fabrics of varying tear strength, color, softness, and ease of care. Many DMEU-related cyclic urea derivatives used to synthesize urea-formaldehyde resins also have applications in treating paper, but DMEU has not proven useful in this regard.


Health concerns

DMEU is a formaldehyde derivative and thus has been known to cause irritation of the skin and allergic reactions from those who are exposed to the resin for extended periods of time. DMEU is a mild irritant and if consumed in moderate quantities may have adverse effects on the body. Additionally, DMEU is considered carcinogenic to humans based its inclusion as a formaldehyde derivative. In 2004 the WHO International Agency for Research on Cancer designated formaldehyde as a carcinogen, making all of its derivatives also carcinogenic. As a result of these health concerns there are alternate areas of research in ionic crosslinking compounds as opposed to DMEU and other formaldehyde-based crosslinking compounds.


References


Further reading

* Vargantwar, P. H. Preparation of Ionic Cellulose for Wrinkle Resistant Fabrics. 2007. North Carolina State University: Textile Chemistry. Masters Thesis * * *{{cite journal , doi =10.1177/152808378401300404 , title =A Comparison of Aftertreatments to Lower Formaldehyde Release from Cottons Crosslinked with Various Finishing Agents , year =1984 , last1 =Reinhardt , first1 =R. M. , last2 =Harper , first2 =R. J. , journal =Journal of Industrial Textiles , volume =13 , issue =4 , pages =216–227, s2cid =135974769 Ureas Imidazolidinones