JP2019131737A - Migration inhibitor - Google Patents

Abstract

To provide a migration inhibitor having a better migration prevention ability than that of conventional migration inhibitors.SOLUTION: A migration inhibitor contains an N-vinyl lactam copolymer, the copolymer having a structural unit (a) derived from an N-vinyl lactam monomer (A), and a structural unit (b) derived from styrene, the content of the structural unit (b) being 1-19 mass% with the total content of all the structural units being 100 mass%.SELECTED DRAWING: None

Description

The present invention relates to a dye transfer inhibitor. More specifically, the present invention relates to a dye transfer inhibitor suitably used for laundry detergents and the like.

When washing clothes or the like, the dye contained in the clothes or the like may ooze out and may be dyed on other parts. As a technique for preventing this, various additives such as polymers have been developed.
Regarding such additives, for example, Patent Document 1 discloses the following components: (a) 1-vinylpyrrolidone, 1-vinylimidazole having a specific structure, a mixture of 1-vinylimidazole, and 1-vinylpyrrolidone and / or Or a mixture of 1-vinylimidazoles of the specified structure (these contain up to 20% by weight of other monoethylenically unsaturated monomers) and (b) at least one ethylenically unsaturated double bond And / or a copolymer obtained by radical-initiated copolymerization of a mixture of 5 to 80% by weight of a water-insoluble polymer containing in the molecule at least one mercapto group.

Japanese National Patent Publication No. 8-505166

As described above, additives for preventing color transfer (transfer) have been developed in the past, but conventional additives are not sufficient in the ability to prevent transfer and have room for improvement.

This invention is made | formed in view of the said present condition, and it aims at providing the dye transfer inhibitor excellent in the dye transfer prevention ability rather than the conventional dye transfer inhibitor.

As a result of various studies on the dye transfer inhibitor, the present inventor found that the copolymer of N-vinyllactam monomer and styrene has a conventional ratio of the structural unit derived from styrene. It has been found that the anti-migrating agent is superior to the anti-migrating agent. Conventional dye transfer inhibitors have a sufficient dye transfer prevention effect due to low adsorbability and dispersibility to dyes and / or due to the fact that dyes re-adhere to cloth based on high adsorbability to cloth It wasn't. For example, in the evaluation of dye transfer prevention with a solution containing a dye, a high value is exhibited if it is excellent in the adsorptivity and dispersibility to the dye. However, since the dye is released from the garment under actual use conditions, if the adsorptivity to the cloth is high, the adsorption to the cloth occurs before it is adsorbed to the release dye. As a result, the expected dye transfer prevention effect cannot be exhibited.
On the other hand, the present inventors have a high ability to adsorb and disperse the dye on the dye and have a low adsorbability to the cloth, so that the adsorption and dispersion performance to the dye can be sufficiently exhibited. It was found that the dye transfer prevention ability is superior to that of conventional dye transfer prevention agents. Thus, the inventors have conceived that the above-mentioned problems can be solved brilliantly and have reached the present invention.

That is, the present invention is a dye transfer inhibitor containing an N-vinyl lactam copolymer, wherein the copolymer is derived from a structural unit (a) derived from an N-vinyl lactam monomer (A) and styrene. And the content ratio of the structural unit (b) is 1 to 19% by mass with respect to 100% by mass of all the structural units.

The N-vinyl lactam monomer (A) is preferably vinyl pyrrolidone.

The present invention is also a method for producing a dye transfer inhibitor containing an N-vinyl lactam copolymer, wherein the production method is a monomer containing an N-vinyl lactam monomer (A) and styrene. Including a step of polymerizing components in an aqueous solution, and the method for producing a dye transfer inhibitor, wherein the content of styrene in the monomer component is 1 to 19% by mass with respect to 100% by mass of all monomers. is there.

The present invention is also a detergent composition containing the above dye transfer inhibitor.

The dye transfer inhibitor of the present invention has the above-described structure, has a high ability to adsorb and disperse the dye, and has a low adsorptivity to cloth, and is superior in the dye transfer prevention ability than the conventional dye transfer inhibitor. It can be suitably used for detergents and the like.

Although the preferable form of this invention is demonstrated concretely below, this invention is not limited only to the following description, In the range which does not change the summary of this invention, it can change suitably and can apply. In addition, the form which combined each preferable form of this invention described below 2 or 3 or more also corresponds to the preferable form of this invention.

<N-vinyl lactam copolymer>
The copolymer contained in the dye transfer inhibitor of the present invention (hereinafter also referred to as the copolymer of the present invention) is derived from the structural unit (a) derived from the N-vinyl lactam monomer (A) and the styrene. And the content ratio of the structural unit (b) is 1 to 19% by mass with respect to 100% by mass of all the structural units.
In the copolymer, the proportion of the structural unit (a) is preferably 81 to 99% by mass with respect to 100% by mass of the copolymer. As a result, the adsorptivity and dispersibility of the copolymer to the dye are further improved. More preferably, it is 83-95 mass%, More preferably, it is 85-95 mass%, More preferably, it is 87-95 mass%, Most preferably, it is 90-95 mass%.

In the copolymer, the proportion of the structural unit (b) is preferably 3 to 19% by mass with respect to 100% by mass of the copolymer.
Thereby, the adsorptivity and dispersibility of the copolymer to the dye and the effect of suppressing the adsorption to the cloth are further improved.
More preferably, it is 5-17 mass%, More preferably, it is 5-15 mass%, More preferably, it is 5-13 mass%, Most preferably, it is 5-10 mass%.

The copolymer may have a structural unit (e) derived from a vinyl lactam monomer (A) and another monomer (E) other than styrene, and the proportion of the structural unit (e) Is preferably 0 to 10% by mass relative to 100% by mass of the copolymer. More preferably, it is 0-5 mass%, More preferably, it is 0-3 mass%, Most preferably, it is 0 mass%.

The N-vinyl lactam monomer (A) is not particularly limited as long as it is a monomer having a cyclic N-vinyl lactam structure, but the following formula (1);

(In formula, R < ¹ >, R < ² >, R < ³ >, R < ⁴ > is the same or different, and represents the C1-C10 alkyl group which may have a hydrogen atom or a substituent. It represents an integer of 4. n is preferably a structure represented by 1 to 3).
The number of carbon atoms of the alkyl group in the above ^R 1 to R ^4, 1 to 6, and more preferably from 1 to 4. The alkyl group is more preferably a methyl group or an ethyl group, and particularly preferably a methyl group. Although it does not restrict | limit especially as a substituent in said R < ¹ > -R < ⁴ >, A carboxyl group, a sulfonic acid group, these esters, and salts; An amino group, a hydroxyl group, etc. are mentioned. R ^{1 to} R ³ are preferably hydrogen atoms. R ⁴ is preferably a hydrogen atom or a methyl group, more preferably a hydrogen atom.
m is preferably an integer of 0 to 2, more preferably an integer of 0 to 1, and most preferably 0.
n is preferably 1 or 2, and more preferably 1.

Examples of the compound represented by the above formula (1) include N-vinylpyrrolidone, N-vinyl-5-methylpyrrolidone, N-vinylpiperidone, N-vinylcaprolactam, 1- (2-propenyl) -2-pyrrolidone and the like. 1 type, or 2 or more types can be used. As N-vinyl lactam, an unsaturated monomer having a pyrrolidone ring is preferable. More preferred is N-vinylpyrrolidone.

The copolymer of the present invention may have a structural unit (e) derived from a vinyl lactam monomer (A) and another monomer (E) other than styrene.
Examples of the other monomer (E) include (i) unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid and salts thereof; (ii) fumaric acid, maleic acid, methylene glutaric acid, itaconic acid and the like. Unsaturated dicarboxylic acids and salts thereof (which may be mono- or di-salts); (iii) (poly) alkylene glycol-containing unsaturated sulfonic acids such as 2- (meth) allyloxyethylene sulfonic acid, 3- (meth) allyloxy-3-hydroxypropanesulfonic acid, 2- (meth) allyloxyethylenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, p-styrenesulfonic acid, α-methyl-p-styrenesulfone Acid, vinylsulfonic acid, vinylsulfamic acid, (meth) allylsulfonic acid, isoprenesulfonic acid, 4- (allyloxy) ) Benzenesulfonic acid, 1-methyl-2-propene-1-sulfonic acid, 1,1-dimethyl-2-propene-1-sulfonic acid, 3-butene-1-sulfonic acid, 1-butene-3-sulfonic acid 2-acrylamido-1-methylpropanesulfonic acid, 2-acrylamidopropanesulfonic acid, 2-acrylamido-n-butanesulfonic acid, 2-acrylamido-2-phenylpropanesulfonic acid, 2-((meth) acryloyloxy) ethane Unsaturated sulfonic acids such as sulfonic acids and their salts; (iv) hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 3- (meth) allyloxy-1,2-dihydroxypropane, (meth) allyl alcohol, Alkyle is added to unsaturated alcohols such as isoprenol and their hydroxyl groups. (V) N, N-dimethylaminoethyl (meth) acrylate, (meth) acrylamide, N-monomethyl (meth) acrylamide, N-monoethyl (meth) acrylamide, N, N-dimethyl (Vi) (meth) acrylic acid-2-sulfone; N-substituted or unsubstituted (meth) acrylamide such as (meth) acrylamide, vinyl pyridine, vinyl imidazole, and salts thereof or quaternized products thereof; (vi) (meth) acrylic acid-2-sulfone (Vii) methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate, (meth) acrylic acid 2 -Ethylhexyl, n-octyl (meth) acrylate, ( (Ta) (meth) acrylic acid esters such as iso-nonyl acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate; (viii) α-methylstyrene, vinyltoluene, indene, vinylnaphthalene, phenylmaleimide, Vinyl aryl monomers other than styrene such as vinylaniline; (ix) (poly) alkylene glycol (meth) acrylates such as ethylene glycol (meth) acrylate and diethylene glycol (meth) acrylate; (x) acrylonitrile, methacrylonitrile and the like These vinyl cyanide monomers may be used alone or in combination of two or more.
In addition, as a salt in said (i)-(iii), (v), a metal salt, ammonium salt, an organic amine salt, etc. are illustrated. Examples of the alkylene oxide in the above (iv) and (ix) include ethylene oxide, propylene oxide and the like, an alkylene oxide having 1 to 20 carbon atoms is preferable, and an alkylene oxide having 1 to 4 carbon atoms is more preferable. The number of moles of the alkylene oxide added is preferably 0 to 50 moles, more preferably 0 to 20 moles per mole of the compound (iv), and preferably 1 to 50 moles per mole of the compound (ix). 1-20 mol is more preferable.

The copolymer preferably has a weight average molecular weight of 1,000 to 1,000,000.
As a result, the effects of the present invention can be more fully exhibited.
More preferably, it is 2000-500000 as a weight average molecular weight, More preferably, it is 3000-200000, More preferably, it is 4000-100000, Most preferably, it is 5000-50000.
The said weight average molecular weight can be measured by the method as described in an Example.

<Method for producing dye transfer inhibitor>
The method for producing the copolymer contained in the dye transfer inhibitor of the present invention is not particularly limited, but can be produced by polymerizing the monomer component. Specific examples and preferred examples of the monomer component, and The preferred ratio of each monomer is as described above.
The method for producing the copolymer preferably includes a step of polymerizing a monomer component containing N-vinyllactam monomer (A) and styrene (hereinafter also referred to as “polymerization step”).

The method for initiating the polymerization of the monomer component in the polymerization step is not particularly limited. For example, a method of adding a polymerization initiator, a method of irradiating UV, a method of applying heat, and in the presence of a photoinitiator. Examples include a method of irradiating light.
In the polymerization step, it is preferable to use a polymerization initiator.
Examples of the polymerization initiator include hydrogen peroxide; persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate; dimethyl 2,2′-azobis (2-methylpropionate), 2,2′- Azobis (isobutyronitrile), 2,2′-azobis (2-methylpropionamidine) dihydrochloride, 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate 2,2′-azobis [2- (2-imidazolin-2-yl) propane], 2,2′-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride, 2,2 ′ -Azo compounds such as azobis (1-imino-1-pyrrolidino-2-methylpropane) dihydrochloride; benzoyl peroxide, lauroyl peroxide, peracetic acid, di-t-butyl peroxide, cumene hydro Preferred are organic peroxides such as peroxides; redox initiators that generate radicals by combining an oxidizing agent and a reducing agent, such as ascorbic acid and hydrogen peroxide, and a persulfate and metal salt. Of these polymerization initiators, since residual monomers tend to decrease, hydrogen peroxide, persulfate, and azo compounds are preferable, and azo compounds are most preferable. These polymerization initiators may be used alone or in the form of a mixture of two or more.

As the usage-amount of the said polymerization initiator, with respect to 1 mol of monomer usage-amounts (total usage-amount of N-vinyl lactam monomer (A), styrene, and another monomer (E)). 0.1 g or more and 15 g or less, preferably 0.1 g or more and 12 g or less, more preferably 0.1 g or more and 10 g or less.

In the polymerization step, a chain transfer agent may be used as necessary. Specific examples of chain transfer agents include thiol chain transfer agents such as mercaptoethanol and mercaptopropionic acid; halides such as carbon tetrachloride and methylene chloride; secondary alcohols such as isopropyl alcohol and glycerin; hypophosphorous acid Acid, hypophosphorous acid (salt) such as sodium hypophosphite (including these hydrates); phosphorous acid (salt) such as phosphorous acid and sodium phosphite; sulfurous acid (salt) such as sodium sulfite ); Bisulfite (salt) such as sodium bisulfite; dithionite (salt) such as sodium dithionite; pyrosulfite (salt) such as potassium pyrosulfite, and the like. The chain transfer agent may be used alone or in the form of a mixture of two or more.
The amount of the chain transfer agent used is preferably 0 g or more and 30 g or less, and more preferably 0 g or more and 15 g or less, per 1 mol of the monomer (total monomer) used.

In the polymerization step, when a solvent is used, the solvent is one or two selected from water, methyl alcohol, ethyl alcohol, isopropyl alcohol (2-propanol), n-butyl alcohol, diethylene glycol, and other alcohols. The above is exemplified. As the solvent, water is preferable.
Since the ratio of styrene in the monomer component is 1 to 19% by mass with respect to 100% by mass of all monomers, the monomer component can be sufficiently polymerized in an aqueous solution. By using water as a solvent, it can be used for detergent applications or the like without performing a step of replacing the solvent after the polymerization reaction.
That is, the polymerization step is preferably performed in an aqueous solution. The present invention is also a method for producing a dye transfer inhibitor containing an N-vinyl lactam copolymer, and the production method includes N-vinyl lactam. A step of polymerizing a monomer component containing a monomer (A) and styrene in an aqueous solution, wherein the content ratio of styrene in the monomer component is 1% with respect to 100% by mass of all monomers. It is also a manufacturing method of the dye transfer inhibitor which is -19 mass%.
As the usage-amount of the said solvent, 40-1000 mass% is preferable with respect to 100 mass% of monomers.

In the above polymerization step, the polymerization temperature is not particularly limited, but a relatively low temperature is preferable because the molecular weight of the copolymer is large, and the polymerization rate is within the range of 60 ° C to 100 ° C. It is further preferable because it improves further. The reaction time is appropriately set according to the reaction temperature, the type (property) and combination of the monomer component, the polymerization initiator, and the solvent, the amount used, etc. so that the polymerization reaction is completed. That's fine.

<Dye>
There are no particular restrictions on the type of dye with which the dye transfer inhibitor of the present invention can exhibit the dye transfer preventing ability, and any dye that is usually used for dyeing clothes or the like may be used. For example, a direct dye, an acid dye, Examples thereof include basic dyes, mordant dyes, acid mordant dyes, disperse dyes, reactive dyes, and fluorescent whitening dyes.
The dye is preferably a water-soluble dye such as a direct dye or an acid dye. Since the water-soluble dye easily loses its color during washing, the technical significance of the present invention is more effectively exhibited.

<Detergent composition>
The dye transfer inhibitor of the present invention can be used in a detergent composition (cleaner composition). That is, this invention is also a detergent composition containing the said dye transfer inhibitor.
The detergent composition is preferably for clothing and is preferably used for laundry detergents and the like.

It is preferable that content of the said dye transfer inhibitor in the said detergent composition is 0.1-20 mass% with respect to 100 mass% of detergent compositions. More preferably, it is 0.1-15 mass%, More preferably, it is 0.1-10 mass%.

The detergent composition usually contains surfactants and additives used in detergents. Specific forms of these surfactants and additives are not particularly limited, and conventionally known knowledge can be appropriately referred to in the detergent field. The detergent composition may be a powder detergent composition or a liquid detergent composition.

The surfactant is one or more selected from the group consisting of an anionic surfactant, a nonionic surfactant, a cationic surfactant and an amphoteric surfactant.

Examples of anionic surfactants include alkylbenzene sulfonate, alkyl ether sulfate, alkenyl ether sulfate, alkyl sulfate, alkenyl sulfate, α-olefin sulfonate, α-sulfo fatty acid or ester salt, alkane sulfonate. , Saturated fatty acid salt, unsaturated fatty acid salt, alkyl ether carboxylate, alkenyl ether carboxylate, amino acid type surfactant, N-acyl amino acid type surfactant, alkyl phosphate ester or salt thereof, alkenyl phosphate ester or Its salts are preferred. An alkyl group such as a methyl group may be branched from the alkyl group or alkenyl group in these anionic surfactants.

Nonionic surfactants include polyoxyalkylene alkyl ethers, polyoxyalkylene alkenyl ethers, polyoxyethylene alkyl phenyl ethers, higher fatty acid alkanolamides or alkylene oxide adducts thereof, sucrose fatty acid esters, alkyl glycoxides, fatty acid glycerin mono Esters, alkylamine oxides and the like are preferred. An alkyl group such as a methyl group may be branched from the alkyl group or alkenyl group in these nonionic surfactants.

As the cationic surfactant, a quaternary ammonium salt or the like is suitable. As the amphoteric surfactant, a carboxyl type amphoteric surfactant, a sulfobetaine type amphoteric surfactant, and the like are suitable. The alkyl group and alkenyl group in these cationic surfactants and amphoteric surfactants may be branched from an alkyl group such as a methyl group.

The blending ratio of the surfactant is usually 10 to 60% by mass, preferably 15 to 50% by mass, more preferably 20 to 45% by mass, and particularly preferably based on the total amount of the detergent composition. Is 25-40 mass%. If the surfactant content is too small, sufficient detergency may not be achieved, and if the surfactant content is too high, the economy may be reduced.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples. Unless otherwise specified, “part” means “part by mass” and “%” means “% by mass”.

<Measurement conditions of weight average molecular weight (GPC)>
Equipment: Tosoh high-speed GPC equipment (HLC-8320GPC)
Detector: RI
Column: SHODEX Asahipak GF-310-HQ, GF-710-HQ, GF-1G 7B manufactured by Showa Denko KK
Column temperature: 40 ° C
Flow rate: 0.5 ml / min
Calibration curve: Polyethylene Glycol, Polyethylene Oxide manufactured by GL Science
Eluent: 0.1N sodium acetate / acetonitrile = 3/1 (mass ratio)

<Measurement of solid content>
The copolymer (1.0 g of copolymer added with 3.0 g of water) was allowed to stand for 1 hour in an oven heated to 130 ° C. and dried. From the mass change before and after drying, the solid content (%) and the volatile component (%) were calculated.

<Evaluation of ability to prevent dye transfer>
The anti-transfer ability was measured by the following method. In evaluating the dye transfer prevention ability, first, a liquid detergent formulation and a 2.0% aqueous polymer solution were prepared. 25% sodium polyoxyethylene lauryl ether sulfate (product name: Emal 20C, manufactured by Kao) 11.0 g, polyoxyethylene lauryl ether (product name: Emargen 108, manufactured by Kao) 2.8 g and 16% sodium dodecylbenzenesulfonate ( (Product name: Neoperex G-15, manufactured by Kao) 17.2 g, 3 g of propylene glycol, 1.2 g of sodium oleate and 1 g of ethanol were added with pure water to 50.0 g, and stirred to obtain a liquid detergent composition. Prepared. The 2.0% polymer aqueous solution used was prepared by diluting the polymer with an appropriate amount of water to a solid content concentration of 2.0% by mass. Next, after adding 500 g of 50 ppm Ca ion hardness water to 0.6 g of the prepared liquid detergent composition and 0.3 g of 2.0% polymer aqueous solution in a 500 ml beaker, 0.005 g of chlorazole black was added and stirred. 1 g of 5 cm × 5 cm cotton fabric (Testfabrics, Style 460-6) was added to the solution, and the mixture was stirred at 25 ° C. for 15 minutes. Thereafter, the obtained cotton cloth was rinsed with 500 g of 50 ppm (Ca / Mg = 3/1) hardness water for 15 minutes, and this rinsing process was repeated again to obtain a dyed cloth. The dye transfer cloth obtained in this step and the white cotton cloth before evaluation were measured with a color difference meter (manufactured by Nippon Denshoku Industries Co., Ltd., spectroscopic color difference meter SE-6000) to evaluate the ability of the polymer to prevent dye transfer. . Regarding the evaluation results, 0% represents the same color strength as that of the test cloth washed without adding the polymer, and 100% represents that the test cloth maintains the color strength before the evaluation. That is, the higher the value, the higher the ability to prevent dye transfer.

<Evaluation of adsorptivity to cotton fabric>
The adsorptivity of the polymer to cotton cloth was evaluated by the following method. First, the polymer was diluted with an appropriate amount of water to prepare a polymer aqueous solution having a solid concentration of 1.0%. In a 300 ml beaker, 2.5 g of the above 1% polymer aqueous solution was added, and 50 ppm (Ca / Mg = 3/1) hardness water was added to make 250.0 g. To this dilute polymer aqueous solution, 10 g of a cotton fabric (Testfabrics, Style460-6) of 5 cm × 5 cm was added and stirred for 10 minutes. The total organic carbon content (TOC) of the aqueous polymer solution obtained after the above process (after the cotton cloth was charged) and the total organic carbon content before the cotton cloth was charged in the above process were measured. Based on the following formula (2), the polymer The adsorption rate to cotton cloth was estimated. The total organic carbon content was measured using a TOC meter (manufactured by Shimadzu Corporation, TOC-L).

<Example 1> Synthesis of copolymer 1 A 500 mL glass separable flask equipped with a reflux condenser and a stirrer (paddle blade) was charged with 176.2 g of pure water and heated to 80 ° C while stirring. Thus, a polymerization reaction system was obtained. Next, 80.0 g of N-vinylpyrrolidone (hereinafter also referred to as “NVP”), 4.2 g of styrene, 10% 2,2′-azobis (in a polymerization reaction system maintained at 80 ° C. with stirring. 20.4 g of 2-methylpropionamidine) dihydrochloride (hereinafter also referred to as “10% V-50”) was dropped from separate nozzles. The dropping time of each solution was 120 minutes for NVP, 120 minutes for styrene, and 120 minutes for 10% V-50. Moreover, the dropping rate of each solution was made constant, and each solution was dropped continuously. After completion of the dropwise addition, the reaction solution was kept (aged) at 80 ° C. for 120 minutes to complete the polymerization. Thus, a polymer aqueous solution having a solid content concentration of 30% was obtained. The weight average molecular weight of the polymer (Copolymer 1) was 14,300. The ability to prevent dye transfer was 45%, and the adsorptivity to cotton cloth was 4%.

<Comparative Example 1>
The powder product polyvinyl pyrrolidone K-30 manufactured by Nippon Shokubai Co., Ltd. was used to evaluate the ability to prevent dye transfer and the adsorptivity to cotton cloth. The ability to prevent dye transfer was 23%, and the adsorptivity to cotton was 6%.

Comparative Example 2 Synthesis of Comparative Copolymer 1 A glass separable flask having a capacity of 1000 mL equipped with a reflux condenser and a stirrer (paddle blade) was charged with NVP 106.2 g, 1-vinylimidazole 18.8 g, and pure water 300. A polymerization reaction system was prepared by charging 0 g and raising the temperature to 75 ° C. while stirring. Next, 50.0 g of 5% V-50 and 18.7 g of a 27% sodium mercaptopropionate aqueous solution were dropped from separate nozzles into the polymerization reaction system maintained at 75 ° C. with stirring. The dropping time of each solution was 100 minutes for NVP and 70 minutes for a 27% sodium mercaptopropionate aqueous solution. Moreover, the dropping rate of each solution was made constant, and each solution was dropped continuously. After completion of the dropwise addition, the reaction solution was kept (aged) at 75 ° C. for an additional 150 minutes to complete the polymerization. Thus, a polymer aqueous solution with a solid content concentration of 26% was obtained. The weight average molecular weight of the polymer (Comparative Copolymer 1) was 14,400. The ability to prevent dye transfer was 49%, and the adsorptivity to cotton cloth was 27%.

Table 1 shows the results of the dye transfer prevention ability and the adsorptivity evaluation to cotton cloth in Example 1 and Comparative Examples 1 and 2.

As shown in Table 1, the polymer having a structural unit derived from styrene is excellent in dye transfer prevention ability and has low adsorptivity to cotton cloth, so that the polymer is not deactivated by adsorption to cotton cloth. It is considered that the adsorption and dispersion performance to the exuded dye can be sufficiently exhibited. On the other hand, it was confirmed that the polyvinylpyrrolidone of Comparative Example 1 was inferior in the ability to prevent dye transfer in the evaluation method. Since the polymer having a structural unit derived from 1-vinylimidazole of Comparative Example 2 has high adsorptivity to cotton cloth, under actual use conditions, the adsorption of the polymer to the dye and the adsorption to the cloth compete with each other. It is considered that the adsorptivity to the dye is lowered and the ability to prevent dye transfer is lowered.

Claims (4)

A dye transfer inhibitor comprising an N-vinyl lactam copolymer,
The copolymer has a structural unit (a) derived from an N-vinyl lactam monomer (A) and a structural unit (b) derived from styrene,
The content transfer rate of this structural unit (b) is 1-19 mass% with respect to 100 mass% of all the structural units, The dye transfer inhibitor characterized by the above-mentioned. The dye transfer inhibitor according to claim 1, wherein the N-vinyl lactam monomer (A) is vinyl pyrrolidone. A method for producing a dye transfer inhibitor comprising an N-vinyl lactam copolymer,
The production method includes a step of polymerizing a monomer component containing an N-vinyl lactam monomer (A) and styrene in an aqueous solution,
A method for producing a dye transfer inhibitor, wherein the content ratio of styrene in the monomer component is 1 to 19% by mass with respect to 100% by mass of all monomers. A detergent composition comprising the dye transfer inhibitor according to claim 1 or 2.