Hydrophobic group-containing copolymer

Abstract

The present invention aims to provide a polymer capable of well dispersing hydrophobic particles. The present invention relates to a hydrophobic group-containing copolymer including a structural unit (A) derived from a hydrophobic group-containing monomer that is represented by the formula (1) and a structural unit (B) derived from a carboxylic acid-based monomer. The proportion of the structural unit (A) is from 16% by mass or more to 50% by mass or less based on 100% by mass of the structural units derived from all monomers constituting the copolymer, and the copolymer has a weight average molecular weight of 10,000 to 1,000,000. ##STR00001##

Claims

1. A hydrophobic group-containing copolymer comprising: a structural unit (A) derived from a hydrophobic group-containing monomer; and a structural unit (B) derived from a carboxylic acid-based monomer, the hydrophobic group-containing monomer being represented by the formula (2): ##STR00004## wherein R.sup.0 represents a hydrogen atom or a CH.sub.3 group; R.sup.a represents a CH.sub.2 group, a CH.sub.2CH.sub.2 group, or a direct bond; and R.sup.1 represents a C1-C20 hydrophobic organic group, the proportion of the structural unit (A) being from 30% by mass to 45% by mass based on 100% by mass of the structural units derived from all monomers constituting the copolymer, and the copolymer having a weight average molecular weight of 10,000 to 100,000.

2. The hydrophobic group-containing copolymer according to claim 1, wherein the copolymer includes a structural unit derived from a sulfonic acid (salt) group-containing monomer.

3. The hydrophobic group-containing copolymer according to claim 1, wherein the copolymer has a weight average molecular weight of 18,000 to 100,000.

4. A detergent composition comprising: the copolymer according to claim 1; and a surfactant.

5. A method for preparing a detergent composition comprising adding the copolymer according to claim 1 to a detergent.

Description

DESCRIPTION OF EMBODIMENTS

(1) The following examples illustrate the present invention in more detail. They are, however, by no means limitative of the scope of the invention. Unless otherwise mentioned, the term part(s) means part(s) by weight and % means % by mass.

Conditions for Measuring Weight Average Molecular Weight

(2) Apparatus: High performance GPC apparatus (HLC-8320GPC) produced by Tosoh Corporation Detector: RI Column: SHODEX Asahipak GF-310-HQ, GF-710-HQ, GF-1G 7B produced by Showa Denko K.K. Column temperature: 40 C. Flow rate: 0.5 mL/min Calibration curve: POLYACRYLIC ACID STANDARD produced by Sowa Kagaku Co., Ltd. Eluent: 0.1 N sodium acetate/acetonitrile=3/1 (mass ratio)

Example 1

(3) (Synthesis of Monomer)

(4) A 500-mL four-necked glass flask equipped with a reflux condenser and a stirrer (paddle fins) was charged with 370.0 g of n-butyl alcohol and 4.27 g of pelletized sodium hydroxide. The temperature was raised to 60 C. while stirring. Next, 57.0 g of allyl glycidyl ether (hereinafter, also referred to as AGE) was added over 30 minutes and then reacted for 5 hours. The resulting solution was transferred to a 1,000-mL recovery flask, and the solvent was removed with a rotary evaporator. To the recovery flask was added 200.0 g of a 20% by mass aqueous solution of sodium chloride. The resulting aqueous solution was transferred to a 500-mL separately funnel, sufficiently shaken, and allowed to stand until the phases separated. Then, the lower phase was removed. The remaining upper phase was transferred to a 300-mL recovery flask, and the solvent was removed with a rotary evaporator. The precipitated salt was removed by filtration. Thus, a monomer (1) was obtained.

Polymerization

(5) A 1,000-mL glass separable flask equipped with a reflux condenser and a stirrer (paddle fins) was charged with 100.0 g of pure water and 0.0116 g of Mohr's salt. The temperature was raised to 85 C. while stirring to prepare a polymerization reaction system. Next, to the polymerization reaction system maintained at 85 C. were added dropwise through different nozzles under stirring 175.0 g of a 80% aqueous solution of acrylic acid (hereinafter, also referred to as 80% AA), 60.0 g of the monomer (1), 49.8 g of a 15% aqueous solution of sodium persulfate (hereinafter, also referred to as 15% NaPS), and 19.4 g of a 35% aqueous solution of sodium bisulfite (hereinafter, also referred to as 35% SBS). The 80% AA, the monomer (1), the 15% NaPS, and the 35% SBS were added dropwise over 180 minutes, 120 minutes, 210 minutes, and 175 minutes, respectively. Each solution was added dropwise continuously at a constant rate. After the dropwise addition, the reaction solution was maintained (aged) at 85 C. for additional 30 minutes to terminate the polymerization. After the polymerization, the polymerization reaction solution was neutralized by gradual dropwise addition of 137.8 g of a 48% aqueous solution of sodium hydroxide (hereinafter, also referred to as 48% NaOH) while the solution was stirred and cooled down. Thus, an aqueous polymer solution having a solids concentration of 46% was obtained. The weight average molecular weight of the polymer was 55,000.

Example 2

(6) A 1,000-mL glass separable flask equipped with a reflux condenser and a stirrer (paddle fins) was charged with 100.0 g of pure water and 0.0126 g of Mohr's salt. The temperature was raised to 85 C. while stirring to prepare a polymerization reaction system. Next, to the polymerization reaction system maintained at 85 C. were added dropwise under stirring 159.4 g of 80% AA, 85.0 g of the monomer (1), 88.9 g of 15% NaPS, and 38.1 g of 35% SBS in the same manner as in Example 1. After the dropwise addition, the reaction solution was maintained (aged) at 85 C. for additional 30 minutes to terminate the polymerization. After the polymerization, the polymerization reaction solution was neutralized by gradual dropwise addition of 125.4 g of 48% NaOH while the solution was stirred and cooled down. Thus, an aqueous polymer solution having a solids concentration of 46% was obtained. The weight average molecular weight of the polymer was 18,000.

Comparative Example 1

(7) A 45% aqueous solution of a sodium polyacrylate (produced by Nippon Shokubai Co., Ltd.) having a weight average molecular weight of 50,000 was prepared as a comparative polymer (1).

Comparative Example 2

(8) A 1,000-mL glass separable flask equipped with a reflux condenser and a stirrer (paddle fins) was charged with 146.8 g of pure water and 0.0186 g of Mohr's salt. The temperature was raised to 85 C. while stirring to prepare a polymerization reaction system. Next, to the polymerization reaction system maintained at 85 C. were added dropwise through different nozzles under stirring 270.0 g of 80% AA, 11 g of the monomer (1), 60 g of 15% NaPS, and 20 g of 35% SBS. The 80% AA, the monomer (1), the 15% NaPS, and the 35% SBS were added dropwise over 180 minutes, 140 minutes, 190 minutes, and 175 minutes, respectively. Each solution was added dropwise continuously at a constant rate. After the dropwise addition of 80% AA, the reaction solution was maintained (aged) at 85 C. for additional 30 minutes to terminate the polymerization. After the polymerization, the polymerization reaction solution was neutralized by gradual dropwise addition of 197.5 g of 48% NaOH while the solution was stirred and cooled down. Thus, an aqueous polymer solution having a solids concentration of 45% was obtained. The weight average molecular weight of the polymer was 35,000.

Comparative Example 3

(9) A 1,000-mL glass separable flask equipped with a reflux condenser and a stirrer (paddle fins) was charged with 146.8 g of pure water and 0.0186 g of Mohr's salt. The temperature was raised to 85 C. while stirring to prepare a polymerization reaction system. Next, to the polymerization reaction system maintained at 85 C. were added dropwise through different nozzles under stirring 270.0 g of 80% AA, 24 g of the monomer (1), 80 g of 15% NaPS, and 30 g of 35% SBS. The 80% AA, the monomer (1), the 15% NaPS, and the 35% SBS were added dropwise over 180 minutes, 140 minutes, 190 minutes, and 175 minutes, respectively. Each solution was added dropwise continuously at a constant rate. After the dropwise addition of 80% AA, the reaction solution was maintained (aged) at 85 C. for additional 30 minutes to terminate the polymerization. After the polymerization, the polymerization reaction solution was neutralized by gradual dropwise addition of 197.5 g of 48% NaOH while the solution was stirred and cooled down. Thus, an aqueous polymer solution having a solids concentration of 45% was obtained. The weight average molecular weight of the polymer was 60,000.

Measurement of Ability to Disperse Carbon Black

(10) The polymers prepared in Examples 1 and 2 and Comparative Examples 1 to 3 were measured for ability to disperse carbon black in the following way.

(11) In the measurement of ability to disperse carbon black, first, a buffer solution and a 0.1% aqueous polymer solution were prepared. The buffer solution was prepared as follows: pure water was added to 6.76 g of glycine, 5.26 g of sodium chloride, and 0.50 g of 48% sodium hydroxide to prepare 60.0 g of a solution in total; and to the solution were added 0.123 g of calcium chloride dihydrate, 0.056 g of magnesium chloride hexahydrate, and pure water to prepare 1000.0 g of a solution. The 0.1% aqueous polymer solution was prepared by diluting each of the polymers obtained in Examples 1 and 2 and Comparative Examples 1 to 3 with an appropriate amount of water to adjust the solids concentration of the polymer to 0.1% by mass.

(12) Next, the solution and carbon black powder were put into a 30-mL test tube in the following order and amounts: firstly 0.03 g of carbon black powder, secondly 27.0 g of a buffer solution, and finally 3.0 g of a 0.1% aqueous polymer solution.

(13) After putting the solution and carbon black into the test tube in such an order, the test tube was sealed and slowly inverted 60 times so that the contents are stirred. Thereafter, the test tube was allowed to stand at room temperature for 20 hours. Immediately after 20-hour standing, the supernatant was put into a 1-cm quartz cell and measured for absorbance at a UV wavelength of 380 nm using a spectrophotometer (measurement apparatus: UV-1800 produced by Shimadzu Corporation). Table 1 shows the results. Higher absorbance indicates higher dispersion of the carbon black powder.

(14) TABLE-US-00001 TABLE 1 Ratio between structural units (% by mass) Structural unit (A)/ Polymer Mw Structural unit (B) Absorbance Example 1 55000 30/70 1.00 Example 2 18000 40/60 1.52 Comparative 50000 0/100 0.01 Example 1 Comparative 35000 5/95 0.27 Example 2 Comparative 60000 10/90 0.79 Example 3