Oil agent for carbon-fiber-precursor acrylic fiber, oil agent composition for carbon-fiber-precursor acrylic fiber, oil-treatment-liquid for carbon-fiber-precursor acrylic fiber, and carbon-fiber-precursor acrylic fiber bundle

1. An oil agent,

comprising:

a hydroxybenzoate (A) of formula (1a);

an amino-modified silicone (H) of formula (3e); and

an organic compound (X) which has affinity with the hydroxybenzoate (A) and a residual mass rate (R 1 ) of 70 to 100 mass % at 300° C. measured by thermogravimetry in air and which is liquid at 100° C.:

wherein in formula (1a), R 1a is a C8 to C20 hydrocarbon group,

wherein in formula (3e), “qe” and “re” are any number of 1 or greater, “se” is any number of 1 to 5, and the dimethylsiloxane units and methylaminoalkyl-siloxane units are in a random sequence.

2. The oil agent according to claim 1 , wherein the organic compound (X) is at least one type selected from a group of types consisting of

a cyclohexanedicarboxylate (B) of formula (1b),

a cyclohexanedicarboxylate (C) of formula (2b), and

a fatty acid ester of polyoxyethylene bisphenol A (G) of formula (2e); and

the oil agent satisfies conditions (a) and (b):

Condition (a): a mass ratio of the total content of hydroxybenzoate (A), amino-modified silicone (H) and organic compound (X) to a content of amino-modified silicone (H) [(H)/[(A)+(H)+(X)]] is 0.05 to 0.8; and

Condition (b): a mass ratio of the total content of hydroxybenzoate (A) and organic compound (X) to a content of hydroxybenzoate (A) [(A)/[(A)+(X)]] is 0.1 to 0.8;

wherein in formula (1b), R 1b and R 2b are each independently a C8 to C22 hydrocarbon group;

wherein in formula (2b), R 3b and R 5b are each independently a C8 to C22 hydrocarbon group, and R 4b is a C2 to C10 hydrocarbon group or residue obtained by removing two hydroxyl groups from a polyoxyalkylene glycol consisting of a C2 to C4 oxyalkylene group;

wherein in formula (2e), R 4e and R 5e are each independently a C7 to C21 hydrocarbon group, and “oe” and “pe” are independently any number of 1 to 5.

3. The oil agent according to claim 2 , wherein the mass ratio [(H)/[(A)+(H)+(X)]] is 0.2 to 0.8.

4. The oil agent according to claim 2 , wherein the mass ratio [(H)/[(A)+(H)+(X)]] is 0.4 to 0.8.

5. The oil agent according to claim 2 , wherein the mass ratio [(H)/[(A)+(H)+(X)]] is 0.5 to 0.8.

6. An oil agent composition, comprising:

an oil agent according to claim 1 ; and

a nonionic surfactant.

7. The oil agent composition according to claim 6 , wherein the nonionic surfactant is contained at 10 to 100 parts by mass relative to 100 parts by mass of the oil agent.

8. An oil-treatment-liquid, comprising:

an oil agent composition according to claim 6 ,

wherein the oil agent composition is dispersed in water.

9. A carbon-fiber-precursor acrylic fiber bundle, comprising:

carbon fiber precursor acrylic fibers, wherein an oil agent is applied thereon, and

the oil agent comprises

a hydroxybenzoate (A) of formula (1a);

an amino-modified silicone (H) of formula (3e) below; and

an organic compound (X), which has affinity with the hydroxybenzoate (A), and a residual mass rate (R1) of 70 to 100 mass % at 300° C. measured by thermogravimetry in air, and which is liquid at 100° C.:

wherein in formula (1a), R 1a is a C8 to C20 hydrocarbon group;

wherein in formula (3e), “qe” and “re” are respectively any number of 1 or greater, “se” is any number of 1 to 5, and the dimethylsiloxane units and methylaminoalkyl-siloxane units are in a random sequence.

10. The carbon-fiber-precursor acrylic fiber bundle according to claim 9 , wherein the organic compound (X) is at least one type selected from a group of types consisting of

a cyclohexanedicarboxylate (B) of formula (1b),

a cyclohexanedicarboxylate (C) of formula (2b), and

a fatty acid ester of polyoxyethylene bisphenol A (G) of formula (2e); and

the oil agent satisfies conditions (a) and (b):

Condition (a): a mass ratio of the total content of hydroxybenzoate (A), amino-modified silicone (H) and organic compound (X) to a content of amino-modified silicone (H) [(H)/[(A)+(H)+(X)]] is 0.05 to 0.8; and

Condition (b): a mass ratio of the total content of hydroxybenzoate (A) and organic compound (X) to a content of hydroxybenzoate (A) [(A)/[(A)+(X)]] is 0.1 to 0.8;

wherein in formula (1b), R 1b and R 2b are each independently a C8 to C22 hydrocarbon group;

wherein in formula (2b), R 3b and R 5b are each independently a C8 to C22 hydrocarbon group, and R 4b is a C2 to C10 hydrocarbon group or residue obtained by removing two hydroxy groups from a polyoxyalkylene glycol consisting of a C2 to C4 oxyalkylene group;

wherein in formula (2e), R 4e and R 5e are each independently a C7 to C21 hydrocarbon group, and “oe” and “pe” are independently 1 to 5.

11. The carbon-fiber-precursor acrylic fiber bundle according to claim 10 , wherein the mass ratio [(H)/[(A)+(H)+(X)]] is 0.2 to 0.8.

12. The carbon-fiber-precursor acrylic fiber bundle according to claim 10 , wherein the mass ratio [(H)/[(A)+(H)+(X)]] is 0.4 to 0.8.

13. The carbon-fiber-precursor acrylic fiber bundle according to claim 10 , wherein the mass ratio [(H)/[(A)+(H)+(X)]] is 0.5 to 0.8.

14. The carbon-fiber-precursor acrylic fiber bundle according to claim 9 , wherein a nonionic surfactant is further adhered to the carbon-fiber-precursor acrylic fiber bundle.

15. A method for producing a carbon-fiber bundle, comprising:

heating a carbon-fiber-precursor acrylic bundle according to claim 9 at a temperature of from 200 to 300° C. in an oxidizing atmosphere under tension to convert the carbon-fiber-precursor acrylic bundle to a stabilized fiber bundle; and

carbonizing the stabilized fiber bundle at an upper temperature of 1000° C. or higher in an inert atmosphere.