Whealth Lohmann Centralin (GZ) Co.Ltd.,China

Abstract This paper briefly introduces the current laundry care market and the overall development trend in recent years,discusses in detail the four most popular laundry care claims in the market,analyzes the overall upgrading of the laundry care market,and looks forward to the future prospects.

Key words long-term laundry care; dye transfer inhibition; anti-bacterial; softness; anti-shrinkage; anti-wrinkle

New upgrade of laundry care market

Since the reform and opening up,the consumption upgrading brought by economic revitalization has been promoting the whole laundry industry from basic “laundry cleaning” to comprehensive “laundry care”.In recent two years,the demands of the people in new era have upgraded from “ever-growing material and cultural needs” to“ever-growing demand for a better life”.Consumers’tireless pursuit of high-quality life drives the traditional “instant laundry care” upgrade to the more refined and focused “long-term laundry care”.

Chinese laundry care market has a huge scale,reaches an overall size of about 45 billion in 2019.The centralization of brands is obvious,and the top ten brands occupy 60% of the market share.Nowadays,in laundry care market,young consumers have become the main consumer group,and their consumption demand is becoming more and more diversified.At the same time,along with people’s increasing consumption ability,high-end laundry care has attracted more and more attention.From the perspective of category,the consumption of laundry detergent with the special function which can meeting the needs of subdivided use scenarios increased significantly,such as fragrance laundry detergent,antibacterial and anti-mite detergent,underwear detergent,et al.The consumption of some subcategory laundry products such as laundry capsules,scent boosters,laundry sanitizers and fabric sprays is also growing rapidly.In the future,the laundry capsules will be the most popular laundry care products,and many businesses have invested in the market in advance for commercial layout.

At present,the development trend of laundry care market is possessing the following four features:concentrated: since its entry into the market,laundry capsules have been strongly sought after by young consumers.The (detergent dosage)/(piece of clothing)is rapidly upgraded from traditional 5g/piece to 1g/piece.As is more environmental friendly and energy saving,concentrated detergent perfectly conforms to the current green sustainable development concept,and in the 13th Five-Year Plan of national light industry,concentrated laundry product industry is listed as the key industry to encourage development;convenience: laundry capsules bring not only concentrated active substances,but also convenient using experience! Compare to the past when doing laundry,many kinds of laundry products such as detergent,softener,scent booster,laundry sanitizer,collar cleaner,etc.,are used in one wash,nowadays,with the popular slogan——“easy toss,clean whole family clothing”,deeply penetrated into modern consumers,multi-functional laundry capsules have become a label of quality life; natural: at present,detergent is faced with an unavoidable problem——Environmental and health hazards.As more and more people gradually understand the raw materials of detergents,traditional petroleum based raw materials have gradually stepped off the stage of history,and major brands have begun to widely use natural plants/Chinese herbal sourced raw materials,such as APG,amino acids,cyclic lipopeptides,GLDA,etc.,to promote "green and natural" as the core selling point; long term effects: consumers pay more and more attention to the long-term laundry care effects.Long-lasting scent,long-term bacteriostasis,color protection,and stain resistance have become the most representative new selling points in recent two years.

Hot claims in laundry care market

Nowadays,economics have improved significantly,people’s pursuit of quality life is getting higher and higher,which has effectively promoted the comprehensive upgrading of the laundry care market:color care products are the new favorite of young consumers; antibacterial products have rapidly entered thousands of families after the outbreak of the covid-19 epidemic; the softer is being favored by the majority of young mothers; anti-wrinkle/antishrinkage spray quietly accepted by white-collar consumer groups.

Color care

“Do not mix-wash clothes of different colors.” as the key laundry note has long been popular.However,in the face of the increasingly fast pace of urban life and the increasingly rich colors in the wardrobe,washing clothes of different colors separately not only wastes more water and electricity resources,but also consumes plenty of time.Consumers’ demand for mix-washing clothes of different colors is increasing strongly.In the face of this urgent problem,the mainstream products on the laundry care market usually adopt the following three solutions.

Blue light compensation——fluorescent brighteners

Traditional methods use visual interference to achieve the color rejuvenation of clothing,mainly using fluorescent brighteners to absorb UV light to emits blue or purple fluorescence,complementary with the original yellow light on the fabrics to form white light,giving a visual sense of whitening and color enhancement.Although fluorescent brightener has a certain brightening effect on the color of clothes,but in practice (a) cannot solve the problem of color fading of dark color clothes and color transferring to light color clothes; and (b)the potential carcinogenicity makes the majority of consumers gradually give up using related products(Chinese regulation on fluorescent brighteners: no transferable fluorescent substances can be detected in daily necessities).In the color care market,fluorescent brighteners are gradually replaced by the following two new technologies.

It is worth mentioning that in the face of the above concerns,polymerized fluorescent brighteners (PFBs) have been launched in European and American markets with improved safety,environmental friendly and efficiency,which may become the key ice-breaker in the future.

Reduce diffuse reflection——cellulase

In considering chemical composition,more than 90% of cotton fiber and more than 60% of raw hemp fiber is cellulose.Cellulose consists of crystalline and amorphous regions.The cellulose molecules in the crystalline region are arranged orderly and tightly,so the limited intermolecular space cannot accommodate the entry of external molecules.The structure of the amorphous region is loose.Water molecules can easily penetrate in between cellulose molecules to form hydrogen bonds during washing,enlarge the distance between the cellulose molecules in the amorphous region.At this time,although cellulase which is more than 1 000 times larger than water molecule cannot enter into the amorphous region,it is easy to adsorb on the fiber surface through the pores of the amorphous region,affecting the adjacent β-1,4-glucoside bond,makes the fine fiber fall off under the action of biodegradation and mechanical force,obtain smooth fiber surface,effectively reduce the diffuse reflection of light,and realize fabrics color enhancement.[1]

Cellulase may cause slight damage to fabrics in the process of cutting fine fibers on the surface,it cannot prevent dyes transferring to the fabric.However,in the past two years,enzyme chemistry has made great progress—in 2018,the Nobel Prize in Chemistry was awarded for the directed evolution of enzymes,and in 2020,the Nobel Prize in chemistry was awarded to the development of a method for genome editing,giving enzyme promising prospect in application of color care.

Chemical coating——polymerized color care agent

Adding polymer with film-forming function on the surface of fabric is a more effective way to improve the color care performance of liquid detergent.Generally used color care polymer can form a film on the surface of the fabric to reduce the dissolution of the original dyes and prevent fading.At the same time,the film can also effectively prevent the adsorption of free dyes.On the other hand,the free color care polymer molecules in the solution can grab the free dyes in the solution to prevent color transferring effect (Figure 1).Although the color care polymer has good anti-color-fading and anticolor-transferring effect,it is easy to react with the original added dyes in liquid detergent due to its strong reacting ability,cause phase separation or even precipitation in long-term storage.The typical representative of this kind of color care polymer is the non-ionic polymer polyvinylpyrrolidone (PVP).[2]However,with the improvement of living standards,consumers have higher requirements on the color care performance of laundry products,driving more and more new technologies and new polymers applied in the market.

Figure 1.Mechanism of dye transfer inhibitor

In practical application,polyamine cannot only adsorb on the fabric surface to prevent color fading,but also can combine with free dyes in solution to avoid re-adsorption.With such good color care effects,polyamine is highly valued in the market.

Dicyandiamide-formaldehyde polymer,the earliest polyamine color care agent,was first reported by E.benberge in 1891.It is a cationic polymer formed by polycondensation of dicyandiamide and formaldehyde in the presence of strong acid or salt.The cationic part of the polymer can form ionic bonds with the dye anions to realize color fixation.At the same time,hydroxymethyl group can form stable covalent bond with the hydroxyl group in cotton fiber,so as to improve the washing resistance and anti-color-fading performance (Figure 2,upper right).However,dicyandiamide-formaldehyde polymer releases a large amount of formaldehyde when treating fabric,which has been gradually abandoned.[3]

Figure 2.Examples of dye transfer inhibitor on market

The subsequent developed aldehyde free color care agent,Diethylenetriamine-dicyandiamide polymer,is mainly made of polyamines (such as diethylenetriamine) and guanidine derivatives (such as dicyandiamide).The cations in the polymer can also form ionic bonds with anions in the dye to improve the color fastness (Figure 2,bottom right).The polymer contains a large number of imino groups whose nitrogen has lone electron pairs which can form intermolecular hydrogen bonds with the hydroxyl groups on cotton fiber,further improve the longterm color care performance,leading to better color care performance than dicyandiamide-formaldehyde polymer.However,those amine/imine groups are easy to be oxidized and turn yellow.At the same time,there are a lot of cationic quaternary ammonium structures in the polymer,which are easy to interact with anionic surfactants in liquid detergents,resulting in phase separation and loss of detergency.[4]

At present,to achieve better compatibility with liquid detergent,quaternary ammonium color care agent——polydimethyldiallylammonium chloride is now wildly used in the market.Polydimethyldiallylammonium chloride can form insoluble precipitates to seize the free dyes in the solution,and form a film on the surface of the fabrics to reduce the loss of dyes (Figure 2,upper left).However,polydimethyldiallylammonium chloride still has cationic property,further structural modification is still required for better application in liquid detergent.[5]

The latest developed HP-66K-vinylpyrrolidone/v i nyl i m id a z ole c op oly me r,d e sig ne d by BASF combines the structural advantages of polydimethyldiallylammonium chloride and traditional PVP.It not only inherits the good adsorption ability on fabrics from PVP,but also continues the characteristics of high color fastness of polydimethyldiallylammonium chloride by forming color precipitates with anions in dyes,and further reduces the cationic property of the molecule,greatly improves its compatibility in anionic surfactant system,resulting in a good application prospect (Figure 2,bottom left).

Among the new launched laundry care products in the past two years,color care detergent has always been one of the core categories.It is believed that with the in-depth application of more and more new technologies and materials,mix-washing clothes of different colors will soon be realized.

Sterilization and disinfection

SARS in 2003 introduces disinfection and sterilization products to thousands of families,which has grown to 10 billion scale in the past ten years.With the outbreak of covid-19 epidemic in the world,it once again triggered a rush to buy disinfection and sterilization products.Due to the long-term survival ability of covid-19 in the air,hard surfaces and fabrics,a challenge of making daily clothes a powerful shield to protect the health and prevent the invasion of bacteria and viruses,rather than a hotbed for virus and bacteria to hide and grow,has been raised.The sales of long-term antibacterial laundry products have exploded in the past year.

In recent years,the rapidly developed long-term antibacterial products mainly focus on quaternary ammonium polymer,this paper will briefly describe three representative examples.

Quaternized silicon softener has strong adsorption ability to the fabric surface with negative charge/hydroxyl group,resulting in good washing resistance ensures sufficient quaternary ammonium terminal to firmly adsorb on the negative charged surface of bacteria even at low dosage,which can increase the permeability of cell wall,produce bacteria cytolysis,and play a good long-term antibacterial performance.

Chitosan/chitin is derived from natural extract,colorless and tasteless,and has good film-forming property.It is usually combined with polycarboxylic acid,which can produce covalent bond with hydroxyl group on cotton fiber and chitosan/chitin,and achieve the anti-wrinkle and long-term antibacterial performance of cotton fabric.Chitosan/chitin can combine with phosphatic acid in peptidoglycan layer of Gram-positive bacteria,resulting in leakage of intracellular components; destroying the integrity of cell wall of Gram-negative bacteria and chelating with metal ions,affecting the intake of important nutrients of bacteria; interacting with negative charges on the surface of fungal cell membrane and penetrating into fungi,inhibit the synthesis of nucleic acid and protein.[6]

Polyhexamethylene biguanide (PHMB) is a cationic oligomer,which contains 16 or more biguanidine units.Each biguanidine unit has two cationic groups.High molecular weight PHMB can form multiple ionic linkage with the fiber surface,and has high binding strength.When some of the cationic groups combine with the fabric surface,the remaining free cationic groups can be electrostatic adsorbed on the anionic sites of bacteria surface,thus hindering the lysozyme action of cells,denaturing or destroying the surface structure of cells,thus inhibiting bacterial reproduction.

As the continuous invasion of new bacterial and viruses,new disinfection and sterilization products are still constantly emerging.Consumers are gradually used to using sterilization and disinfection products in their daily life.In the future,the prospect of sterilization and disinfection products is expected,the laundry industry will contribute more and more to the protection of public health and the prevention of the invasion of new bacteria and viruses in public.

Softness

With the improvement of living standards,people begin to pursue better wearing experience in their daily life.Therefore,the industry has paid more and more attention to the soft finishing of textiles.Among the numerous softener materials,silicone softener can effectively reduce the surface energy of the fabric and make it more flexible,easy to slide,fluffy and easy to bend.At the same time,it can enhance the surface gloss and wear resistance of the fabric.It has become the first choice in the market because of its excellent characteristics.

In order to comply with the market trend and the upgrading of consumer demand,various kinds of modified silicone softeners are constantly introduced.The introduction of special functional groups gives the traditional silicone softeners more superior performance,effectively taking into account people‘s various demands for laundry,which is widely favored.The following chapter will briefly introduce some representative examples of modified silicone softener.

Amino modified silicone softener contains strong polar amino groups,which can form hydrogen bonds with hydroxyl group and carboxyl group in cellulose structure,which brings good orientation and washing resistance (Figure 3,bottom left),makes the organic groups point towards the fabric surface uniformly,reduces the friction coefficient between fibers,greatly reduces the surface energy of the fabric,achieves good softening effect,and is widely used in various kinds of natural fiber and synthetic fiber,known as “super soft”.However,the primary and secondary amino groups are easy to be oxidized and yellowing under heat or ultraviolet radiation.Although the yellowing problem can be improved by acylation,the fabrics treated with amino modified silicone softener still have the disadvantages of low hydrophilicity and poor hygroscopicity.[7-10]

Figure 3.Evolution of silicone oil

The epoxy group in epoxy modified silicone softener can react with hydroxyl group,carboxyl group and amino group on the fiber to form stable covalent bond (Figure 3,upper left),which improves its washing resistance on the fabric surface,avoids the yellowing problem of amino silicone softener at high temperature,and endows the fabric with soft,smooth and fluffy characteristics.At the same time,epoxy modified silicone softener can be self-cross-linked,producing better film-forming property and washing resistance on the finished fabric,and the anti-wrinkle and anti-shrinkage advantages of the fabric are given at the same time.However,due to the introduction of hydrophobic epoxy group,the hydrophilicity of the finished fabric decreased.Therefore,epoxy modified silicone softener alone can only be used for white or light colored fabrics,and it still needs further modifications to make up own shortcomings and broaden the application scenarios.[7]

Polyether modified silicone softener generally refers to the silicone chain with polyoxyethylene(EO) and/or polyoxypropylene (PO) attached to the side chain (Figure 3,upper right).Polyether modified silicone softener gives the fabric a certain degree of hydrophilicity,antistatic property,softness,smoothness and antifouling property,but its softness is reduced; at the same time,it is a non-reactive silicone softener with poor washing resistance.In polyether part,EO is hydrophilic and PO is lipophilic.By adjusting the ratio of EO/PO,the required hydrophilic and lipophilic balance can be achieved.[7,10]

Quaternized silicone softener has a strong adsorption on negatively charged fabric.Even at low doses,it can effectively reduce the static electricity and friction between fibers (Figure 3,bottom right),enhance the hydrophilic and antistatic ability of the finished fabric.Moreover,the positively charged quaternary ammonium group can adsorb on the surface of negative charged bacteria,increase cell permeability,induce cytolysis and inhibit the growth of bacteria.

Single modified silicone softener can only meet one aspect or some requirements in finishing fabric,and there are still various limitations in its application.In order to meet the overall needs of consumers and achieve better comprehensive finishing effect,mixmodified silicone softener with multiple efficacy characteristics has gradually become the mainstream in the market,among which polyether modified amino silicone softener is the most representative.Of which,ammonia value and molecular weight are the two most important parameters determining performance (Table 1).[10-13]

Table 1.Effects of ammonium value ＆ molecular weight on characters of silicone softener

Due to its unique structure and performance,silicon softener has shown great application potential in soft finishing field.Various modified silicone softeners have been innovating to fulfill the everchanging demand of market.With the prosperity of the laundry market,softeners are becoming more and more popular.It is believed that more and more mixmodified silicone oil with better performance will continuously emerge into the market.

Anti-shrinkage/wrinkle

There are always all kinds of unexpected embarrassment in life.In the morning,you wear plain and neat clothes to company.After fighting in the subway and the elevator,it only takes half a day for the clothes to wrinkle.When you get home from work at night,after throw your clothes into the washing machine,you forget them completely.The next day,you are faced with wrinkled clothes.The demand of consumers is the pursuit of businesses.All kinds of Anti-shrinkage/wrinkle spray are rapidly becoming popular among white-collar users.

The first thing to know is why clothes shrink and deform when they are washed? First of all,fabrics are made of fibers,which are locked by hydrogen bonds,when exposed to heat/water,hydrogen bonds break and fibers move freely.Then,after the fabric cools/dehydrates,the new hydrogen bond is re-formed and the fabrics are deformed (Figure 4,left).On the other hand,as the fibers absorb water,the diameter increases,the adjacent interweaved fibers are forced to be squeezed closer.After dehydration,these fibers cannot be restored to their original position,so the fabric shrinks (Figure 4,right).The factors that can reduce the friction between fibers,such as stirring and using softener,will aggravate shrinkage.

Figure 4.Mechanisms of the formation of shrinkage ＆ wrinkle of fabrics

The film-forming characteristics of the polymer made of bisphenol A glycidyl ether and amino modified siloxane are usually used in the market to form a transparent non hydrophilic film on the surface of the fabric,so that the treated clothing has the effect of repelling water molecules and achieving the effect of anti-wrinkle and anti-shrinkage.

More and more subdivision scenarios have spawned more new products.The rise of anti-wrinkle spray is both accidental and inevitable.Although the anti-wrinkle technology is not yet mature at this stage,the booming market will surely push more businesses to join in and bring more pleasant experience to consumers.

New technology of laundry care market

With the rapid development of science and technology,the laundry care market is not only constantly breaking through the innovation of raw materials,but also constantly changing the market pattern with many laundry care technologies:

(a) Hydrophobic T-shirt: it is made of hightech fabric developed by super nano hydrophobic technology.The surface layer of the fabric contains silica particles,which can prevent the adhesion and penetration of water,oil and stains on the fabric.The T-shirt can be worn for a long time without cleaning.When washing,just rinse it with water.

(b) Air washing: Haier company has launched a new type of washing machine uses ultrasonic "air washing" technology to convert water into micron sized fog particles,which can directly penetrate the clothes to remove stains and release wrinkles.

(c) RKK energiya,a Russian manufacturer of ballistic missiles,spacecraft and space stations,has developed a “space washing machine” that collects exhaled carbon dioxide gas and converts it into a liquid under high pressure for dry wash.

The reform and opening up not only brings about the progress of science and technology,but also brings about the higher pursuit of the quality life of consumers in the new era.Throughout the current laundry care market,the simple “instant care”products in the past have been gradually upgraded to various “long-term care” products with rich categories and complete functions.More consumers have the will and ability to pursue higher quality products,which effectively promotes the new types of laundry products to constantly launched and give consumers all-round care of clothing,and promoting the global market of laundry care to get wider and wider.