Polymer composition, lubricating oil additive, viscosity index improver, lubricating oil composition, method for producing a polymer composition, and method for producing a macromonomer

Abstract

To provide a polymer composition, a lubricant additive, a viscosity index improver, and a lubricant composition, having a high viscosity index improving effect.SOLUTION: Provided is a polymer composition wherein the differential distribution value in the differential molecular weight distribution curve of the polymer composition as measured by gel permeation chromatography satisfies formula 1, and the maximum value of normalized back scattering intensity of a 35 wt% base oil solution of the polymer composition, where the size q of the scattering vector of small angle X-ray scattering at 25°C is in the range of 0.07 nm-1 or more to 2 nm-1 or less, is 40 cm-1 or more.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a polymer composition used for engine oil and the like, a lubricant additive, a viscosity index improver, a lubricant composition, a method for producing a polymer composition, and a method for producing a macromonomer. This application claims priority based on Japanese Patent Application No. 2020-055130 filed in Japan on March 25, 2020, and Japanese Patent Application No. 2020-055131 filed in Japan on March 25, 2020, the contents of which are incorporated herein by reference.

Background Art

[0002] Lubricant compositions used for engine oils, gear oils, etc. of automobiles and the like require a certain viscosity that can protect components over a wide range from low temperature to high temperature.

[0003] However, the viscosity of conventional lubricant compositions decreases at high temperatures, and their original performance cannot be exhibited. In addition, in response to recent fuel efficiency improvements, it is desired to reduce the viscosity of lubricating oils in the practical temperature range while suppressing the decrease in viscosity at high temperatures (improving the viscosity index).

[0004] For this reason, for example, Patent Document 1 and Patent Document 2 describe viscosity index improvers composed of (meth)acrylate polymers having long-chain alkyl groups.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, with the methods described in Patent Document 1 and Patent Document 2, the effect of improving the viscosity index is insufficient.

[0007] An object of the present invention is to solve these problems.

Means for Solving the Problems

[0008] The gist of the present invention is a polymer composition containing a (meth)acrylic copolymer A, wherein the (meth)acrylic copolymer A is a copolymer containing a structural unit derived from an alkyl methacrylate a1 having 5 to 14 carbon atoms in the alkyl group, a structural unit derived from an alkyl acrylate a2 having 5 to 14 carbon atoms in the alkyl group, and a structural unit derived from an alkyl acrylate a3 having 1 to 4 carbon atoms in the alkyl group.

[0009] The gist of the present invention is a polymer composition, wherein the differential distribution value in the differential molecular weight distribution curve of the polymer composition measured by gel permeation chromatography satisfies the following formula 1, and the magnitude q of the scattering vector of small-angle X-ray scattering at 25 °C of a 35 wt% base oil solution of the polymer composition is 0.07 nm -1 or more and 2 nm -1 The maximum value of the normalized scattering intensity is 40 cm -1 or more. dMp30 / dMp ≧ 0.65 ··· 1 · dMp30: Differential distribution value of the molecular weight corresponding to 30% of the peak top molecular weight measured by gel permeation chromatography. · dMp: Differential distribution value of the peak top molecular weight measured by gel permeation chromatography. · Base oil: API standard Group III, or Group III plus

[0010] [1] A polymer composition, The differential distribution value represented by the following formula (1) in the differential molecular weight distribution curve of the polymer composition measured by gel permeation chromatography is 0.65 or more, preferably 0.70 or more and 1.0 or less, more preferably 0.75 or more and 1.0 or less, and even more preferably 0.80 or more and 1.0 or less. The magnitude q of the scattering vector of small-angle X-ray scattering at 25 °C of a 35 wt% base oil solution of the polymer composition is 0.07 nm -1 or more and 2 nm -1 The maximum value of the normalized scattering intensity in the following range is 40 cm -1 or more, and 40 cm -1 or more and 1100 cm -1 or less is more preferable, and 60 cm -1 or more and 500 cm -1 or less is even more preferable, and 80 cm -1 or more and 450 cm -1 or less is even more preferable, the polymer composition. dMp30 / dMp ··· 1 · dMp30: Differential distribution value of the molecular weight corresponding to 30% of the peak top molecular weight measured by gel permeation chromatography. · dMp: Differential distribution value of the peak top molecular weight measured by gel permeation chromatography. · Base oil: API standard GroupIII, or GroupIII plus [2] The polymer composition is a polymer composition containing a (meth)acrylic copolymer A, The (meth)acrylic copolymer A is a copolymer containing a structural unit derived from an alkyl methacrylate a1 having 5 to 14 carbon atoms in the alkyl group, a structural unit derived from an alkyl acrylate a2 having 5 to 14 carbon atoms in the alkyl group, and a structural unit derived from an alkyl acrylate a3 having 1 to 4 carbon atoms in the alkyl group. The polymer composition according to [1]. [3] In the (meth)acrylic copolymer A, the content of the structural unit derived from the alkyl methacrylate a1 is preferably 1% by mass or more and 50% by mass or less, more preferably 5% by mass or more and 45% by mass or less, and even more preferably 10% by mass or more and 40% by mass or less, based on the total mass of the (meth)acrylic copolymer A. The polymer composition according to [2]. [4] A polymer composition containing the (meth)acrylic copolymer A, wherein the (meth)acrylic copolymer A is a copolymer containing a structural unit derived from an alkyl methacrylate a1 having 5 to 14 carbon atoms in the alkyl group, a structural unit derived from an alkyl acrylate a2 having 5 to 14 carbon atoms in the alkyl group, and a structural unit derived from an alkyl acrylate a3 having 1 to 4 carbon atoms in the alkyl group. In the (meth)acrylic copolymer A, the content of the structural unit derived from the alkyl methacrylate a1 is preferably 1% by mass or more and 50% by mass or less, more preferably 5% by mass or more and 45% by mass or less, and even more preferably 10% by mass or more and 40% by mass or less, based on the total mass of the (meth)acrylic copolymer A. The polymer composition. [5] In the (meth)acrylic copolymer, the content of the structural unit derived from the alkyl acrylate a2 is preferably 1% by mass or more and 50% by mass or less, more preferably 5% by mass or more and 45% by mass or less, and even more preferably 10% by mass or more and 40% by mass or less, based on the total mass of the (meth)acrylic copolymer A. The polymer composition according to any one of [2] to [4]. [6] In the (meth)acrylic copolymer A, the content of the structural unit derived from the alkyl acrylate a3 is preferably 30% by mass or more and 80% by mass or less, more preferably 35% by mass or more and 75% by mass or less, and even more preferably 40% by mass or more and 70% by mass or less, based on the total mass of the (meth)acrylic copolymer A. The polymer composition according to any one of [2] to [5]. [7] A polymer composition containing the (meth)acrylic copolymer A, The (meth)acrylic copolymer A is a copolymer containing a structural unit derived from an alkyl methacrylate a1 having 5 to 14 carbon atoms in the alkyl group, a structural unit derived from an alkyl acrylate a2 having 5 to 14 carbon atoms in the alkyl group, and a structural unit derived from an alkyl acrylate a3 having 1 to 4 carbon atoms in the alkyl group. In the (meth)acrylic copolymer A, the content of the structural unit derived from the alkyl acrylate a3 is preferably 30% by mass or more and 80% by mass or less, more preferably 35% by mass or more and 75% by mass or less, and still more preferably 40% by mass or more and 70% by mass or less, based on the total mass of the (meth)acrylic copolymer A. Polymer composition. [8] In the (meth)acrylic copolymer A, the content of the structural unit derived from the alkyl acrylate a2 is preferably 1% by mass or more and 50% by mass or less, more preferably 5% by mass or more and 45% by mass or less, and still more preferably 10% by mass or more and 40% by mass or less, based on the total mass of the (meth)acrylic copolymer A. The polymer composition according to [7]. [9] The (meth)acrylic copolymer A is a copolymer containing a structural unit derived from an alkoxyalkyl (meth)acrylate a4. The polymer composition according to any one of [2] to [8].

[10] In the (meth)acrylic copolymer A, the content of the structural unit derived from the alkoxyalkyl (meth)acrylate a4 is preferably 1% by mass or more and 30% by mass or less, more preferably 3% by mass or more and 25% by mass or less, and still more preferably 5% by mass or more and 20% by mass or less, based on the total mass of the (meth)acrylic copolymer A. The polymer composition according to [9].

[11] The differential distribution value represented by the following formula in the differential molecular weight distribution curve measured by gel permeation chromatography is 0.65 or more, preferably 0.70 or more and 1.0 or less, more preferably 0.75 or more and 1.0 or less, and still more preferably 0.80 or more and 1.0 or less. The polymer composition according to any one of [1] to

[10] . dMp30 / dMp ···1 ·dMp30: Differential distribution value of the molecular weight corresponding to 30% of the peak top molecular weight. ·dMp: Differential distribution value of the peak top molecular weight.

[12] The magnitude q = 0.1 nm of the scattering vector of small-angle X-ray scattering at 100 °C of the API standard Group III or Group III plus 35 wt% base oil solution of the polymer composition -1 The normalized scattering intensity at is preferably 1 cm -1 or more, and preferably 1.5 cm -1 or more and 100.0 cm -1 or less, more preferably 2 cm -1 or more and 50.0 cm -1 or less, still more preferably the polymer composition according to any one of [1] to

[11] .

[13] The weight average molecular weight of the polymer composition measured by gel permeation chromatography is preferably 50,000 or more and 2,000,000 or less, more preferably 100,000 or more and 1,500,000 or less, still more preferably 150,000 or more and 1,000,000 or less, the polymer composition according to any one of [1] to

[12] .

[14] The molecular weight distribution of the polymer composition measured by gel permeation chromatography is preferably 5 or more and 20 or less, more preferably 6 or more and 18 or less, still more preferably 7 or more and 15 or less, the polymer composition according to any one of [1] to

[13] .

[15] The polymer composition according to any one of [2] to

[14] , wherein the (meth)acrylic copolymer A is a graft copolymer.

[16] The polymer composition according to

[15] , wherein the graft copolymer contains a structural unit derived from a vinyl-based radically polymerizable monomer m1 and a structural unit derived from a macromonomer M other than the vinyl-based radically polymerizable monomer m1.

[17] The polymer composition described in

[16] , wherein the vinyl radical-polymerizable monomer m1 is an alkyl acrylate a2 having 5 to 14 carbon atoms in the alkyl group and an alkyl acrylate a3 having 1 to 4 carbon atoms in the alkyl group.

[18] The polymer composition described in

[16] or

[17] , wherein the macromonomer M contains a structural unit derived from the vinyl radical-polymerizable monomer m2.

[19] The polymer composition described in

[18] , wherein the vinyl radical-polymerizable monomer m2 contains an alkyl methacrylate a1 having 5 to 14 carbon atoms in the alkyl group.

[20] The polymer composition according to any one of

[16] to

[19] , wherein the macromonomer M has the structure of the following formula 2.

[0011] [Chemical formula]

[0012] (In the formula, X 1 ~X n-1 each independently represents a hydrogen atom, a methyl group or CH2OH, and Y 1 ~Y n each independently represents a substituent bonded to the vinyl group of the vinyl radical-polymerizable monomer m2. Z represents a terminal group, and n represents an integer of 2 to 10000.)

[21] In the polymer composition according to any one of

[16] to

[20] , the number average molecular weight of the macromonomer M measured by gel permeation chromatography is preferably 500 to 30000, more preferably 1000 to 25000, and particularly preferably 2000 to 20000.

[22] A lubricating oil additive containing the polymer composition according to any one of [1] to

[21] .

[23] A viscosity index improver containing the polymer composition according to any one of [1] to

[21] .

[24] A lubricating oil composition comprising the polymer composition according to any one of [1] to

[21] .

[25] A method for producing a polymer composition by polymerizing a monomer mixture containing a macromonomer and a vinyl radical polymerizable monomer in a base oil, The method for producing a polymer composition according to any one of [1] to

[21] , wherein the macromonomer is a macromonomer polymerized in a base oil.

[26] The method for producing a polymer composition according to

[25] , wherein α-methylstyrene dimer is used as a chain transfer agent.

[27] A method for producing a macromonomer by polymerizing a monomer mixture containing a vinyl radical polymerizable monomer in a base oil using a cobalt chain transfer agent.

[28] The lubricating oil composition comprising the polymer composition according to

[20] or

[21] and a base oil. [Advantages of the Invention]

[0013] According to the present invention, a polymer composition, a lubricating oil additive, a viscosity index improver, and a lubricating oil composition having a high viscosity index improving effect can be provided. Further, according to the method for producing a polymer composition of the present invention, a polymer composition having a high viscosity index improving effect can be produced. Furthermore, according to the method for producing a macromonomer of the present invention, a macromonomer capable of producing a polymer composition having a high viscosity index improving effect can be produced. [Brief Description of the Drawings]

[0014]

Figure 1

[0015] The polymer composition of the present invention satisfies the following formula (1) for the differential distribution value in the differential molecular weight distribution curve of the polymer composition measured by gel permeation chromatography (GPC). dMp30 / dMp ≧ 0.65 ··· (1) · dMp30: Differential distribution value of the molecular weight corresponding to 30% of the peak top molecular weight measured by gel permeation chromatography. · dMp: Differential distribution value of the peak top molecular weight measured by GPC.

[0016] The polymer composition of the present invention is a mixture of polymers with different structures such as a low molecular weight diblock copolymer and a high molecular weight graft copolymer. The differential molecular weight distribution curve has a broad distribution and has a plurality of peaks or shoulders. By satisfying the above formula (1), the polymer composition of the present invention indicates the presence of a graft copolymer that contributes to the improvement of the viscosity index. From the viewpoint of improving the viscosity index, the dMp30 / dMp is more preferably 0.70 or more, and further preferably 0.75 or more. More specifically, the dMp30 / dMp is preferably 0.70 or more and 2.0 or less, more preferably 0.75 or more and 1.5 or less, and further preferably 0.80 or more and 1.0 or less.

[0017] The polymer composition of the present invention has a maximum value of the normalized scattering intensity in the range where the magnitude q of the scattering vector of small-angle X-ray scattering at 25 °C of a 35 wt% base oil solution of the polymer composition is 0.07 nm -1 or more and 2 nm -1 or less, which is 40 cm -1 or more. More specifically, the maximum value of the normalized scattering intensity is more preferably 40 cm -1 or more and 1100 cm -1 or less, further preferably 60 cm -1 or more and 500 cm -1 or less, and even more preferably 80 cm -1 or more and 450 cm -1 or less.

[0018] The magnitude q of the scattering vector of the small-angle X-ray scattering represents the reciprocal of the interparticle distance in the base oil solution, and the scattering intensity represents the degree of particle nature. However, for the polymer composition of the present invention, the maximum value of the normalized scattering intensity is 40 cm -1 or more, in the base oil at 25°C, the polymer is dispersed in a fine particle structure, and an increase in the viscosity of the base oil at low temperatures can be suppressed.

[0019] The base oil is an oil of API (American Petroleum Institute) standard Group III or Group III plus. The Group III base oil is a mineral oil with a viscosity index (VI) ≥ 120, a saturated hydrocarbon content (Vol.%) ≥ 90, and a sulfur content (MASS%) ≤ 0.03. The Group III plus base oil is a mineral oil with a viscosity index (VI) ≥ 135, a saturated hydrocarbon content (Vol.%) ≥ 90, and a sulfur content (MASS%) ≤ 0.03.

[0020] Furthermore, for the polymer composition of the present invention, the magnitude q of the scattering vector of the small-angle X-ray scattering at 100°C of a 35 wt% base oil solution of the polymer composition is q = 0.1 nm -1 The normalized scattering intensity at this point is 1 cm -1 or more, preferably 1.5 cm -1 or more and 10.0 cm -1 or less, more preferably 2 cm -1 or more and 9.0 cm -1 or less, even more preferably. When the normalized scattering intensity is 1 cm -1 or more, at 100°C, the polymer does not completely dissolve in the base oil and a partially contracted structure remains. Thus, even under conditions of high temperature (150°C) and high shear, the viscosity is more likely to increase.

[0021] Moreover, the weight average molecular weight of the polymer composition measured by GPC is preferably 50,000 or more and 2,000,000 or less, more preferably 100,000 or more and 1,500,000 or less, and even more preferably 150,000 or more and 1,000,000 or less, because the solubility in base oil and viscosity index can be made good.

[0022] Furthermore, the molecular weight distribution of the polymer composition measured by GPC is preferably 5 or more and 20 or less, more preferably 6 or more and 18 or less, and even more preferably 7 or more and 15 or less, because the solubility in base oil and viscosity index can be made good.

[0023] The above molecular weight distribution is a value calculated by weight average molecular weight (Mw) / number average molecular weight (Mn). Moreover, the polymer composition of the present invention preferably contains a (meth)acrylic copolymer A.

[0024] The (meth)acrylic copolymer A means a copolymer in which at least a part of the constituent units is a constituent unit derived from a (meth)acrylic monomer. The (meth)acrylic copolymer A may further contain a constituent unit derived from a monomer other than the (meth)acrylic monomer (for example, styrene, etc.).

[0025] Examples of the (meth)acrylic monomer include (meth)acrylates containing a carboxyl group such as (meth)acrylic acid, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl maleate, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl hexahydrophthalate; (meth)acrylates having an alkyl group such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, i-propyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, s-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl methacrylate, n-heptyl methacrylate, n-octyl methacrylate, n-nonyl (meth)acrylate, n-decyl (meth)acrylate, n-undecyl (meth)acrylate, n-dodecyl (meth)acrylate, n-tridecyl (meth)acrylate, n-tetradecyl (meth)acrylate, isoamyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, behenyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, i-nonyl (meth)acrylate, i-decyl (meth)acrylate, 3-i-propylheptyl (meth)acrylate, i-undecyl (meth)acrylate, 2-t-butylheptyl (meth)acrylate, i-dodecyl (meth)acrylate, i-tridecyl (meth)acrylate, i-tetradecyl (meth)acrylate; (meth)acrylates having a hydroxyl group such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, glycerin mono(meth)acrylate, ethylene glycol mono(meth)acrylate, propylene glycol mono(meth)acrylate;Methacrylates having a cyclic alkyl group such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, adamantyl (meth)acrylate, etc.; (Meth)acrylates having an aromatic ring structure such as phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, nonylphenoxypolyethylene glycol (meth)acrylate, phenoxypolypropylene glycol (meth)acrylate, phenylphenyl (meth)acrylate, phenylphenoxyethyl (meth)acrylate, phenoxybenzyl (meth)acrylate, phenylbenzyl (meth)acrylate, naphthyl (meth)acrylate, (1-naphthyl)methyl (meth)acrylate, etc.; (Meth)acrylates having a heterocyclic structure such as tetrahydrofurfuryl (meth)acrylate, glycidyl (meth)acrylate, (meth)acryloylmorpholine, etc.; Alkoxyalkyl (meth)acrylates such as methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, butoxyethyl (meth)acrylate, 2-ethylhexyldiethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, etc.; 3-(Meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 2-(meth)acryloyloxyethyl acid phosphate, trifluoroethyl (meth)acrylate and heptadecafluorodecyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, (meth)acrylamide, etc. These may be used in combination of two or more kinds.;

[0026] Furthermore, the (meth)acrylic copolymer A is preferably a copolymer containing a structural unit derived from an alkyl methacrylate a1 having an alkyl group with 5 to 14 carbon atoms, a structural unit derived from an alkyl acrylate a2 having an alkyl group with 5 to 14 carbon atoms, and a structural unit derived from an alkyl acrylate a3 having an alkyl group with 1 to 4 carbon atoms.

[0027] Examples of the alkyl methacrylate a1 include methacrylates having a linear alkyl group such as n-pentyl methacrylate, n-hexyl methacrylate, n-heptyl methacrylate, n-octyl methacrylate, n-nonyl methacrylate, n-decyl methacrylate, n-undecyl methacrylate, n-dodecyl methacrylate, n-tridecyl methacrylate, and n-tetradecyl methacrylate; methacrylates having a branched alkyl group such as isoamyl methacrylate, 2-ethylhexyl methacrylate, i-nonyl methacrylate, i-decyl methacrylate, 3-i-propylheptyl methacrylate, i-undecyl methacrylate, 2-t-butylheptyl methacrylate, i-dodecyl methacrylate, i-tridecyl methacrylate, and i-tetradecyl methacrylate; and methacrylates having a cyclic alkyl group such as cyclopentyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, dicyclopentenyl methacrylate, dicyclopentenoxyethyl methacrylate, dicyclopentanyl methacrylate, and adamantyl methacrylate. These may be used in combination of two or more.

[0028] In addition, due to the excellent effect of improving the viscosity index, linear or branched alkyl methacrylates having 8 to 14 carbon atoms are preferred, linear or branched alkyl methacrylates having 10 to 14 carbon atoms are more preferred, and linear or branched alkyl methacrylates having 12 to 14 carbon atoms are even more preferred.

[0029] In addition, since the solubility in the base oil and the viscosity index can be improved, the content of the structural unit derived from the alkyl methacrylate a1 is preferably 1% by mass or more and 50% by mass or less, more preferably 5% by mass or more and 45% by mass or less, and even more preferably 10% by mass or more and 40% by mass or less, based on the total mass of the (meth)acrylic copolymer A. In the present specification, the content of the structural unit can be calculated from the charged amount of the monomer constituting each structural unit.

[0030] Examples of the alkyl acrylate a2 include acrylates having a linear alkyl group such as n-pentyl acrylate, n-hexyl acrylate, n-heptyl acrylate, n-octyl acrylate, n-nonyl acrylate, n-decyl acrylate, n-undecyl acrylate, n-dodecyl acrylate, n-tridecyl acrylate, and n-tetradecyl acrylate; acrylates having a branched alkyl group such as i-amyl acrylate, 2-ethylhexyl acrylate, i-nonyl acrylate, i-decyl acrylate, 3-i-propylheptyl acrylate, i-undecyl acrylate, 2-t-butylheptyl acrylate, i-dodecyl acrylate, i-tridecyl acrylate, and i-tetradecyl acrylate; and acrylates having a cyclic alkyl group such as cyclopentyl acrylate, cyclohexyl acrylate, isobornyl acrylate, dicyclopentenyl acrylate, dicyclopentenoxyethyl acrylate, dicyclopentanyl acrylate, and adamantyl acrylate. These may be used in combination of two or more.

[0031] In addition, since the effect of improving the viscosity index is excellent, a linear or branched alkyl acrylate having 8 to 14 carbon atoms is preferable, a linear or branched alkyl acrylate having 10 to 14 carbon atoms is more preferable, and a linear or branched alkyl acrylate having 12 to 14 carbon atoms is even more preferable.

[0032] In addition, since the solubility in the base oil and the viscosity index can be improved, the constituent unit derived from the alkyl acrylate a2 is preferably 1% by mass or more and 50% by mass or less, more preferably 5% by mass or more and 45% by mass or less, and even more preferably 10% by mass or more and 40% by mass or less, based on the total mass of the (meth)acrylic copolymer A.

[0033] Examples of the alkyl acrylate a3 include acrylates having a linear alkyl group such as methyl acrylate, ethyl acrylate, n-propyl acrylate, and n-butyl acrylate; and acrylates having a branched alkyl group such as i-propyl acrylate, i-butyl acrylate, t-butyl acrylate, and s-butyl acrylate. These may be used in combination of two or more.

[0034] In addition, since the effect of improving the viscosity index is excellent, an alkyl acrylate having 2 to 4 carbon atoms is preferred, an alkyl acrylate having 3 to 4 carbon atoms is more preferred, and an alkyl acrylate having 4 carbon atoms is even more preferred.

[0035] In addition, since the solubility in the base oil and the viscosity index can be improved, the constituent unit derived from the alkyl acrylate a3 is preferably 30% by mass or more and 80% by mass or less, more preferably 35% by mass or more and 75% by mass or less, and even more preferably 40% by mass or more and 70% by mass or less, based on the total mass of the (meth)acrylic copolymer A.

[0036] In addition to the alkyl methacrylate a1, the alkyl acrylate a2, and the alkyl acrylate a3, the (meth)acrylic copolymer A may contain a constituent unit derived from an alkoxyalkyl (meth)acrylate a4 for adjusting the solubility in the base oil and the viscosity index.

[0037] Examples of the alkoxyalkyl (meth)acrylate a4 include methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, butoxyethyl (meth)acrylate, 2-ethylhexyldiethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, and the like. Two or more of these may be used in combination.

[0038] In addition, since the effect of improving the viscosity index is excellent, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, and butoxyethyl (meth)acrylate are preferable, methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate are more preferable, and methoxyethyl (meth)acrylate is even more preferable.

[0039] Further, since the solubility in the base oil and the viscosity index can be made good, the structural unit derived from the alkoxyalkyl (meth)acrylate a4 is preferably 1% by mass or more and 30% by mass or less, more preferably 3% by mass or more and 25% by mass or less, and even more preferably 5% by mass or more and 20% by mass or less with respect to the total mass of the (meth)acrylic copolymer A.

[0040] In addition to the alkyl methacrylate a1, the alkyl acrylate a2, the alkyl acrylate a3, and the alkoxyalkyl (meth)acrylate a4, the (meth)acrylic copolymer A may contain a structural unit derived from another vinyl-based radically polymerizable monomer for adjusting the solubility in the base oil and the viscosity index.

[0041] Examples of other vinyl radical polymerizable monomers include vinyl compounds such as styrene and vinyl acetate; (meth)acrylates containing a carboxyl group such as (meth)acrylic acid, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl maleate, 2-(meth)acryloyloxyethyl phthalate, and 2-(meth)acryloyloxyethyl hexahydrophthalate; alkyl methacrylates having 1 to 4 carbon atoms such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, i-propyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, and s-butyl methacrylate; alkyl (meth)acrylates having 15 or more carbon atoms in the alkyl group such as cetyl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate; (meth)acrylates having a hydroxyl group such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, glycerin mono(meth)acrylate, ethylene glycol mono(meth)acrylate, and propylene glycol mono(meth)acrylate; (meth)acrylates having an aromatic ring structure such as phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, nonylphenoxypolyethylene glycol (meth)acrylate, phenoxypolypropylene glycol (meth)acrylate, phenylphenyl (meth)acrylate, phenylphenoxyethyl (meth)acrylate, phenoxybenzyl (meth)acrylate, phenylbenzyl (meth)acrylate, naphthyl (meth)acrylate, and (1-naphthyl)methyl (meth)acrylate; (meth)acrylates having a heterocyclic structure such as tetrahydrofurfuryl (meth)acrylate, glycidyl (meth)acrylate, and (meth)acryloylmorpholine;;Examples include 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 2-(meth)acryloyloxyethyl acid phosphate, trifluoroethyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, (meth)acrylamide, etc. Two or more of these may be used in combination.;

[0042] The (meth)acrylic copolymer A may be a block copolymer, a random copolymer, or a graft copolymer. Since it is possible to obtain a good viscosity index by including a plurality of structural units having different solubilities in the base oil, a graft copolymer is particularly preferred. The graft copolymer preferably includes a structural unit derived from a vinyl-based radically polymerizable monomer m1 and a structural unit derived from a macromonomer M other than m1. Note that two or more macromonomers M may be used in combination. It is preferable to include a structural unit derived from the macromonomer M as a branch component of the graft copolymer. It is preferable to include a structural unit derived from the monomer m1 described later as a trunk component of the graft copolymer.

[0043] Examples of the monomer m1 include styrene, vinyl acetate, (meth)acrylate compounds, etc. Examples of the (meth)acrylate compounds include the alkyl methacrylate a1, the alkyl acrylate a2, and the alkyl acrylate a3. Examples of other (meth)acrylate compounds include (meth)acrylic acid, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl maleate, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl hexahydrophthalate, etc. (meth)acrylates containing a carboxyl group; alkyl methacrylates having 1 to 4 carbon atoms such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, i-propyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, s-butyl methacrylate; alkyl (meth)acrylates having 15 or more carbon atoms in the alkyl group such as cetyl (meth)acrylate, stearyl (meth)acrylate, behenyl (meth)acrylate; (meth)acrylates having a hydroxyl group such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, glycerin mono(meth)acrylate, ethylene glycol mono(meth)acrylate, propylene glycol mono(meth)acrylate; (meth)acrylates having an aromatic ring structure such as phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, nonylphenoxypolyethylene glycol (meth)acrylate, phenoxypolypropylene glycol (meth)acrylate, phenylphenyl (meth)acrylate, phenylphenoxyethyl (meth)acrylate, phenoxybenzyl (meth)acrylate, phenylbenzyl (meth)acrylate, naphthyl (meth)acrylate, (1-naphthyl)methyl (meth)acrylate; (meth)acrylates having a heterocyclic structure such as tetrahydrofurfuryl (meth)acrylate, glycidyl (meth)acrylate, (meth)acryloylmorpholine; alkoxy (meth)acrylates such as methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate;3-(Meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 2-(meth)acryloyloxyethyl acid phosphate, trifluoroethyl (meth)acrylate and heptadecafluorodecyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, (meth)acrylamide, etc. may be mentioned. These may be used in combination of two or more kinds.;

[0044] In addition, the alkyl methacrylate a1, the alkyl acrylate a2 and the alkyl acrylate a3 may be contained in either one of the monomer m1 and the macromonomer M, or may be contained in both. However, since it is easy to adjust the solubility in the base oil, it is preferable that the vinyl-based radically polymerizable monomer m1 is the alkyl acrylate a2 and the alkyl acrylate a3.

[0045] The macromonomer M is not particularly limited as long as it is a polymer having a radically polymerizable group. However, from the high degree of designability with respect to the solubility in the base oil, it preferably contains two or more structural units derived from the monomer m2 having a vinyl-based radically polymerizable group and is a compound having a radically polymerizable group at the terminal. Examples of the monomer m2 include the same vinyl-based radically polymerizable monomers as those mentioned as the monomer m1. Since the monomer m2 has an excellent effect of improving the viscosity index, it preferably contains an alkyl methacrylate having 5 or more carbon atoms in the alkyl group, and more preferably contains the alkyl methacrylate a1 because of its excellent solubility in the base oil.

[0046] Furthermore, from the viewpoint of radical polymerizability with the monomer m1, the macromonomer M preferably has a structure represented by the following formula 2.

[0047]

Chemical formula

[0048] (In the formula, X 1~X n-1 each independently represents a hydrogen atom, a methyl group or CH2OH. Y 1 ~Y n is a substituent bonded to the vinyl group of the (m2) component which is a monomer constitutional unit, for example, OR 1 , a halogen atom, COR 2 , COOR 3 , CN, CONR 4 R 5 , NHCOR 6 , or R 7 represents, and R 1 ~R 7 each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, a cyclic ether group, a heteroaryl group, etc. Z represents a terminal group, and n represents an integer of 2 to 10,000. ) Note that the terminal group Z includes a hydrogen atom and a group derived from a radical polymerization initiator, similar to the terminal group of a polymer obtained by known radical polymerization.

[0049] Since the solubility in the base oil and the viscosity index can be made good, the number average molecular weight of the macromonomer M measured by gel permeation chromatography is preferably 500 to 30,000, more preferably 1,000 to 25,000, and particularly preferably 2,000 to 20,000.

[0050] The macromonomer M may be one produced by a known method or a commercially available one. Examples of the production method of the macromonomer M include a method of producing using a cobalt chain transfer agent (U.S. Patent No. 4,680,352), a method of using an α-substituted unsaturated compound such as α-bromomethylstyrene as a chain transfer agent (International Publication No. 88 / 04304), a method of chemically bonding a polymerizable group (Japanese Patent Laid-Open No. 60-133007 and U.S. Patent No. 5,147,952), and a method by thermal decomposition (Japanese Patent Laid-Open No. 11-240854).

[0051] A method of production using a cobalt chain transfer agent is preferred in that it uses a catalyst with a small number of manufacturing steps and a high chain transfer constant. Since the cobalt chain transfer agent has a high chain transfer constant, a macromonomer with a controlled molecular weight can be obtained with a small amount of addition.

[0052] As the cobalt chain transfer agent, a known cobalt complex can be used. The amount of the cobalt chain transfer agent is preferably 0.00001 to 0.1 part by mass, more preferably 0.00005 to 0.05 part by mass, and particularly preferably 0.0001 to 0.02 part by mass with respect to 100 parts by mass of the vinyl radical polymerizable monomer m2.

[0053] The polymer composition of the present invention preferably has a total light transmittance of 85 to 95%, more preferably 88 to 93%, and even more preferably 90 to 93% when measured by the method described in the examples below. The polymer composition of the present invention preferably has a viscosity index (VI) calculated by the method of JIS-K2283-1993 of 200 to 300, more preferably 205 to 300, and even more preferably 210 to 300 when measured by the method described in the examples below.

[0054] <Method for producing polymer composition> Next, an example of the method for producing the polymer composition of the present invention is shown. The polymer composition of the present invention can be produced by polymerizing a monomer mixture containing a macromonomer and a vinyl radical polymerizable monomer other than the macromonomer in a base oil by a known method.

[0055] Next, other examples of the method for producing the polymer composition of the present invention are shown. The polymer composition of the present invention can be produced by polymerizing a monomer mixture containing the alkyl methacrylate a1, the alkyl acrylate a2, and the alkyl acrylate a3 in a base oil by a known method.

[0056] Examples of the base oil include mineral base oils refined from crude oil and synthetic oils chemically synthesized. Examples of commercially available products include base oils of API Group III such as YUBASE3 manufactured by SK Lubricants Co., Ltd., and base oils such as API Group III Plus like YUBASE4 manufactured by SK Lubricants Co., Ltd.

[0057] Further, the monomer mixture may contain a macromonomer M. The macromonomer M is preferably a macromonomer obtained by polymerizing a monomer mixture containing a vinyl radical polymerizable monomer in the base oil using a cobalt chain transfer agent. Since the cobalt chain transfer agent has a high chain transfer constant, a macromonomer with a controlled molecular weight can be obtained with a small amount of addition. Further, the macromonomer preferably contains the alkyl methacrylate a1 as a constituent unit.

[0058] Examples of the vinyl radical polymerizable monomer include the polymerizable monomer m1, and preferably includes the alkyl acrylate a2 and the alkyl acrylate a3.

[0059] In the present invention, by polymerizing a monomer mixture containing the macromonomer and a vinyl radical polymerizable monomer other than the macromonomer, the polymer composition of the present invention, which is a mixture of polymers with different structures such as diblock copolymers and graft copolymers, can be obtained.

[0060] The polymerization may be carried out under known conditions, but since it has an excellent effect of suppressing heat generation during polymerization, it is preferable to use α-methylstyrene dimer as a chain transfer agent.

[0061] <Lubricant additive> The polymer composition containing the (meth)acrylic copolymer A of the present invention can be used as a lubricant additive to be added to lubricating oils such as engine oils, gear oils, and hydraulic oils used in mobility applications such as industrial machines, robots, and automobiles.

[0062] Examples of the base oils such as the engine oil, gear oil, and hydraulic oil include mineral base oils refined from crude oil and synthetic oils chemically synthesized. Examples of commercially available products include base oils of API Group III such as YUBASE3 manufactured by SK Lubricants Co., Ltd., and base oils such as API Group III Plus like YUBASE4 manufactured by SK Lubricants Co., Ltd. Examples of the lubricant additives include antioxidants, viscosity index improvers, pour point depressants, detergents, corrosion inhibitors, rust inhibitors, extreme pressure agents, oiliness improvers, defoamers, emulsifiers, antiwear agents, friction modifiers, fungicides, and demulsifiers.

[0063] <Viscosity index improver> The polymer composition of the present invention can be used as a viscosity index improver for the lubricating oil.

[0064] For the viscosity index improver, it is better that the degree of increase in kinematic viscosity due to addition is large at high temperatures and small at low temperatures. Generally, it is known that a viscosity index improver composed of a (meth)acrylate polymer forms a fine particle structure without completely dissolving at low temperatures, and as the temperature rises, the solubility improves, the polymer chains expand, and the aforementioned function is exhibited. As an index of the performance of the viscosity index improver, the viscosity index calculated from the kinematic viscosities at low temperature (for example, 40 °C) and high temperature (for example, 100 °C) is used.

[0065] The viscosity index is a value measured by the method of JIS-K2283-1993, and the larger the numerical value, the smaller the viscosity change due to temperature. In recent years, for viscosity index improvers, a high numerical value is also required for the viscosity (HTHS 150 °C viscosity) under conditions of higher temperature (150 °C) and high shear. Therefore, it is preferable that it does not completely dissolve even at 100 °C and the viscosity improvement effect can be expected even at higher temperatures. The dissolution state at 100 °C can be evaluated, for example, by small-angle X-ray scattering measurement (SAXS).

[0066] <Lubricating oil composition> The lubricating oil composition containing the polymer composition of the present invention may contain various additives in addition to the polymer composition of the present invention. Other additives include antioxidants, viscosity index improvers, pour point depressants, detergents, corrosion inhibitors, rust preventives, extreme pressure agents, oiliness improvers, defoamers, emulsifiers, antiwear agents, friction modifiers, fungicides, demulsifiers, and the like.

[0067] When the total mass of the lubricating oil composition is 100% by mass, the content of the polymer composition of the present invention contained in the lubricating oil composition is preferably 0.01 to 30% by mass, more preferably 0.05 to 25% by mass, and most preferably 0.1 to 20% by mass. By setting the content of the polymer composition to 0.01% by mass or more, the viscosity index of the lubricating oil composition is improved, and by setting it to 30% by mass or less, the kinematic viscosity of the lubricating oil composition at low temperatures is suppressed and the fuel consumption is improved.

Examples

[0068] Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. In the Examples, "parts" represents "parts by mass". The evaluation was measured by the following methods.

[0069] <Molecular weight of polymer composition> It was measured using gel permeation chromatography (GPC) (HLC-8320 manufactured by Tosoh Corporation). After preparing a 0.2% by mass tetrahydrofuran solution of the polymer composition, 10 μl of the above solution was injected into a device equipped with two Tosoh columns (TSKgel SuperHZM-H, inner diameter 6.0 mm, length 15 cm) and a TSKguardcolumn SuperHZ-H (inner diameter 4.6 mm, length 3.5 cm), and measured under the conditions of a flow rate of 0.5 ml / min, an eluent: tetrahydrofuran (stabilizer BHT), and a column temperature of 40°C. The weight average molecular weight (Mw), number average molecular weight (Mn), and peak top molecular weight (Mp) were calculated in terms of standard polystyrene.

[0070] <Molecular weight of macromonomer M> Measurement was carried out using gel permeation chromatography (GPC) (HLC-8320 manufactured by Tosoh Corporation). After preparing a 0.2 mass% tetrahydrofuran solution of macromonomer M, 10 μl of the above solution was injected into an apparatus equipped with columns manufactured by Tosoh Corporation (TSKgel SuperHZM-M (inner diameter 4.6 mm, length 15 cm), HZM-M (inner diameter 4.6 mm, length 15 cm), HZ-2000 (inner diameter 4.6 mm, length 15 cm), TSKguardcolumn SuperHZ-L (inner diameter 4.6 mm, length 3.5 cm)), and measurement was carried out under the conditions of a flow rate of 0.35 ml / min, an eluent of tetrahydrofuran (stabilizer BHT), and a column temperature of 40 °C. The weight average molecular weight (Mw) and number average molecular weight (Mn) were calculated in terms of standard polystyrene conversion.

[0071] <Small-angle X-ray scattering measurement (SAXS)> A base oil solution containing 35 mass% of the polymer composition obtained in the examples was placed in a 2 mmφ quartz capillary, and small-angle X-ray scattering measurements were carried out at measurement temperatures of 25 °C and 100 °C. The small-angle X-ray scattering measurement was carried out using a SAXSpoint2.0 system manufactured by Anton Paar. Regarding the small-angle X-ray scattering measurement conditions, X-ray Cu Kα (wavelength 1.54 Å) was used, the exposure time was 30 min (10 min × 3 times), the measurement environment was vacuum, and the camera length was set to 570 mm.

[0072] X-rays were irradiated onto a capillary sample of the base oil solution of the (meth)acrylic copolymer to obtain a one-dimensional scattering profile. Also, the same measurement as above was carried out on a 2 mmφ quartz capillary containing only the base oil for background correction.

[0073] Background correction was performed from the one-dimensional scattering profile obtained by the above procedure. Specifically, the one-dimensional scattering profile of only the base oil was corrected for transmittance and subtracted from the one-dimensional scattering profile of each sample to obtain a one-dimensional scattering profile after background correction.

[0074] Next, in accordance with Journal of Physics: Conference Series 247 (2010) 012005, the absolute scattering intensity correction of the one-dimensional scattering profile was performed. Specifically, as a sample for absolute scattering intensity correction, small-angle X-ray scattering measurement was carried out on glassy carbon without putting it in a capillary under the same analysis conditions as above, and a one-dimensional scattering profile of glassy carbon was obtained. Next, the one-dimensional scattering profile in the state without the sample was corrected for transmittance and subtracted from the one-dimensional scattering profile of glassy carbon to obtain a one-dimensional scattering profile of glassy carbon after background correction. The one-dimensional scattering profile of glassy carbon after background correction was divided by the thickness (cm) and exposure time (s) to obtain a scattering profile ST per unit thickness and per unit time.

[0075] Next, the differential scattering cross-section of glassy carbon publicly available from the National Institute of Standards and Technology (Nist) of the United States was prepared, and this was divided by the scattering profile ST at each q in the range of -1 0.1 nm ≤ q ≤ 1 nm -1 to obtain a coefficient value at each q. The average value of this coefficient value was used as a scale factor for calculating the differential scattering cross-section. Next, the one-dimensional scattering profile of the base oil solution of each polymer composition after background correction was corrected to the scattering intensity per unit thickness and per unit time by dividing it by the capillary diameter (cm) and exposure time (s), and was multiplied by the scale factor obtained by the above method to obtain a normalized scattering intensity (differential scattering cross-section (cm -1 )) and a normalized scattering profile.

[0076] <Viscosity Index (VI)> In accordance with ASTM D7279 (D445) method, evaluation was carried out using a fully automatic simple kinematic viscometer (manufactured by Cannon, product name; Simple-VIS type). The kinematic viscosity (Vk100) at 100 °C of the polymer composition obtained in this example was adjusted in concentration with YUBASE4 so as to be 6.5 mm 2 / s, and the kinematic viscosity (Vk40) at 40 °C of the polymer composition with further concentration adjustment was measured. Using the obtained "Vk100" and "Vk40", the viscosity index (VI) was calculated by the method of JIS-K2283-1993. <Solubility in Base Oil> A base oil solution containing 35% by mass of the polymer obtained in this example was sandwiched between two 1-mm-thick plate glasses with a 2-mm-thick silicone rubber as a gasket, and the total light transmittance was measured using a haze meter (product name: HM-150 type, manufactured by Murakami Color Technology Laboratory).

[0077] [Production Example 1] (Synthesis of Co Complex (Cobalt Chain Transfer Agent)) Into a synthesis apparatus equipped with a stirring device, under a nitrogen atmosphere, 2.00 g (8.03 mmol) of cobalt(II) acetate tetrahydrate (manufactured by Wako Pure Chemical Industries, Ltd., Wako special grade), 3.86 g (16.1 mmol) of diphenylglyoxime (manufactured by Tokyo Chemical Industry Co., Ltd., EP grade), and 100 ml of diethyl ether that had been deoxygenated by nitrogen bubbling in advance were added, and the mixture was stirred at 25 °C for 2 hours. Next, 20 ml of boron trifluoride diethyl ether complex (manufactured by Tokyo Chemical Industry Co., Ltd., EP grade) was added, and the mixture was further stirred for 6 hours. The obtained product was filtered, the solid was washed with diethyl ether, and dried at 20 °C for 12 hours under 100 MPa or less to obtain 5.02 g (7.93 mmol, yield 99% by mass) of a brown solid Co complex (1).

[0078] [Production Example 2] In a reaction vessel equipped with a stirrer, a cooling pipe, and a thermometer, 50 parts of YUBASE4, 50 parts of acrylate SL (manufactured by Mitsubishi Chemical Corporation, trade name: acrylate SL, a mixture of alkyl methacrylate with 12 carbon atoms in the alkyl group and alkyl methacrylate with 13 carbon atoms in the alkyl group), and 0.0015 part of the Co complex prepared in Production Example 1 were added. While stirring, nitrogen was bubbled to remove dissolved oxygen. After raising the liquid temperature to 85°C, a mixed solution consisting of 50 parts of acrylate SL and 0.5 part of 1,1,3,3-tetramethylbutyl peroxy 2-ethylhexanoate (manufactured by NOF Corporation, trade name: Perocta O), which is a polymerization initiator, was added dropwise over 4 hours. Further, after holding at 85°C for 1 hour, a mixed solution consisting of 35 parts of YUBASE4 and 0.4 part of Perocta O was added, and the temperature was raised to 95°C. After holding the liquid temperature at 95°C for 4 hours, it was cooled to obtain a YUBASE4 solution containing 54% by mass of macromonomer M1. The GPC results of the obtained macromonomer are shown in Table 1.

[0079] [Production Examples 3 to 5] Macromonomers M2 to M4 were obtained in the same manner as in Production Example 2, except that the amount of the Co complex was changed as shown in Table 1. The GPC results are shown in Table 1.

[0080] [Production Example 6] In a reaction vessel equipped with a stirrer, a cooling pipe, and a thermometer, 40 parts of YUBASE4, 98 parts of acrylate SL, 2 parts of methyl methacrylate (manufactured by Mitsubishi Chemical Corporation, trade name: acrylate M), 0.003 part of the Co complex prepared in Production Example 1, and 0.1 part of t-butyl peroxy-2-ethylhexanoate (manufactured by NOF Corporation, trade name: Perbutyl O) as a polymerization initiator were added. While stirring, nitrogen was bubbled to remove dissolved oxygen. The liquid temperature was raised to 90°C and held for 2.5 hours while maintaining at 90°C. Then, a mixed solution consisting of 20 parts of YUBASE4 and 0.7 part of Perbutyl O was added dropwise over 1 hour, and the liquid temperature was raised to 105°C. After holding at 105°C for 1 hour, 30 parts of YUBASE4 was added, and it was cooled to obtain a YUBASE4 solution containing 52.6% by mass of macromonomer M5. The GPC results of the obtained macromonomer are shown in Table 1.

[0081] [Production Example 7] Into a reaction vessel equipped with a stirrer, a cooling pipe, and a thermometer, 60 parts of YUBASE4, 98 parts of acrylate SL, 2 parts of methyl methacrylate, 0.005 part of the Co complex prepared in Production Example 1, and 0.1 part of t-amyl peroxy 2-ethylhexanoate (manufactured by Arkema Kishima Co., Ltd., trade name Lupersol 575) as a polymerization initiator were added. While stirring, nitrogen was bubbled to remove dissolved oxygen. The liquid temperature was raised to 90 °C and maintained at 90 °C for 2.5 hours. Thereafter, a mixed solution consisting of YUBASE4 (10 parts) and Perbutyl O (0.7 part) was added dropwise over 1 hour, and the liquid temperature was raised to 105 °C. After holding at 105 °C for 1 hour, YUBASE4 (20 parts) was further added, and the mixture was cooled to obtain a YUBASE4 solution containing 52.6% by mass of macromonomer M6. The results of GPC of the obtained macromonomer are shown in Table 1.

[0082] [Example 1] Into a reaction vessel equipped with a stirrer, a cooling pipe, and a thermometer, 78.7 parts of YUBASE4, 25 parts of acrylate SL, 52 parts of n-butyl acrylate (manufactured by Mitsubishi Chemical Corporation, trade name: nBA), 23 parts of lauryl acrylate (manufactured by Osaka Organic Chemical Co., Ltd., trade name: LA), 0.03 part of t-butyl peroxy-2-ethylhexanoate (manufactured by NOF Corporation, trade name: Perbutyl O) as a polymerization initiator, and 0.03 part of α-methylstyrene dimer (manufactured by NOF Corporation, trade name: Nofmer MSD) as a chain transfer agent were added. While stirring, nitrogen was bubbled to remove dissolved oxygen. The liquid temperature was raised to 85 °C and held at 85 °C for 2 hours. Then, a mixed solution of YUBASE4 (40 parts) and Perbutyl O (0.015 part) was added dropwise over 2 hours. Further, after holding at 85 °C for 1 hour, a mixed solution consisting of YUBASE4 (67 parts) and Perocta O (0.5 part) was added, and the temperature was raised to 95 °C. After holding the liquid temperature at 95 °C for 1 hour, the mixture was cooled to obtain a solution containing 35% by mass of a (meth)acrylic copolymer. The evaluation results of the obtained polymer composition are shown in Table 2.

[0083] [Example 2] Into a reaction vessel equipped with a stirrer, a cooling pipe, and a thermometer, 38.2 parts of YUBASE3, 46.3 parts of a YUBASE4 solution of the macro monomer M1 obtained in Production Example 2, 52 parts of n-butyl acrylate, 23 parts of lauryl acrylate, 0.015 part of perbutyl O as a polymerization initiator, and 0.04 part of Nofmer MSD as a chain transfer agent were added. While stirring, nitrogen was bubbled to remove dissolved oxygen. The liquid temperature was raised to 85 °C and held at 85 °C for 2 hours, and then a mixed solution of YUBASE3 (42 parts) and perbutyl O (0.015 part) was added dropwise over 2 hours. Further, after holding at 85 °C for 1 hour, a mixed solution composed of YUBASE3 (67.5 parts) and perocta O (0.5 part) was added, the temperature was raised to 95 °C, and the liquid temperature was held at 95 °C for 1 hour. After adding YUBASE3 (16.7 parts), it was cooled to obtain a solution containing 3 5 mass%. The evaluation results of the obtained polymer composition are shown in Table 2.

[0084] <Example 3> Into a reaction vessel equipped with a stirrer, a cooling pipe, and a thermometer, 7.6 parts of YUBASE4, 46.3 parts of a YUBASE4 solution of the macro monomer M2 obtained in Production Example 3, 52 parts of n-butyl acrylate, 23 parts of lauryl acrylate, 0.015 part of perbutyl O as a polymerization initiator, and 0.03 part of Nofmer MSD as a chain transfer agent were added. While stirring, nitrogen was bubbled to remove dissolved oxygen. The liquid temperature was raised to 85 °C and held at 85 °C for 2 hours, and then a mixed solution of YUBASE4 (42 parts) and perbutyl O (0.015 part) was added dropwise over 2 hours. Further, after holding at 85 °C for 1 hour, a mixed solution composed of YUBASE4 (67.5 parts) and perocta O (0.5 part) was added, the temperature was raised to 95 °C, and the liquid temperature was held at 95 °C for 1 hour. After adding YUBASE4 (46.7 parts), it was cooled to obtain a YUBASE4 solution containing 35 mass% of the polymer composition. The evaluation results of the obtained polymer composition are shown in Table 2.

[0085] <Example 7> Into a reaction vessel equipped with a stirrer, a cooling pipe, and a thermometer, 12.5 parts of YUBASE4, 37 parts of a YUBASE4 solution of the macromonomer M2 obtained in Production Example 3, 56 parts of n-butyl acrylate, 24 parts of lauryl acrylate, 0.015 part of perbutyl O as a polymerization initiator, and 0.04 part of Nofmer MSD as a chain transfer agent were added. While stirring, nitrogen was bubbled to remove dissolved oxygen. The liquid temperature was raised to 85°C and maintained at 85°C for 2 hours, and then a mixed solution of YUBASE4 (42 parts) and perbutyl O (0.015 part) was added dropwise over 2 hours. Further, after maintaining at 85°C for 1 hour, a mixed solution composed of YUBASE4 (67.5 parts) and perocta O (0.5 part) was added, the temperature was raised to 95°C, and the liquid temperature was maintained at 95°C for 1 hour. After adding YUBASE4 (46.7 parts), it was cooled to obtain a solution containing 35% by mass of the (meth)acrylic copolymer. The evaluation results of the obtained polymer composition are shown in Table 3.

[0086] <Example 8> Into a reaction vessel equipped with a stirrer, a cooling pipe, and a thermometer, 74 parts of a YUBASE4 solution of the macromonomer M2 obtained in Production Example 3, 42 parts of n-butyl acrylate, 18 parts of lauryl acrylate, 0.015 part of perbutyl O as a polymerization initiator, and 0.02 part of Nofmer MSD as a chain transfer agent were added. While stirring, nitrogen was bubbled to remove dissolved oxygen. The liquid temperature was raised to 85°C and maintained at 85°C for 2 hours, and then a mixed solution of YUBASE4 (42 parts) and perbutyl O (0.015 part) was added dropwise over 2 hours. Further, after maintaining at 85°C for 1 hour, a mixed solution composed of YUBASE4 (67.5 parts) and perocta O (0.5 part) was added, the temperature was raised to 95°C, and the liquid temperature was maintained at 95°C for 1 hour. After adding YUBASE4 (42.2 parts), it was cooled to obtain a solution containing 35% by mass of the (meth)acrylic copolymer. The obtained evaluation results of the polymer composition are shown in Table 3.

[0087] <Example 13> Into a reaction vessel equipped with a stirrer, a cooling pipe, and a thermometer, 40 parts of YUBASE4, 47.6 parts of a YUBASE4 solution of the macro monomer M5 obtained in Production Example 6, 52 parts of n-butyl acrylate, 23 parts of lauryl acrylate, 0.03 part of Luperox 575 as a polymerization initiator, and 0.03 part of Nofmer MSD as a chain transfer agent were added. While stirring, nitrogen was bubbled to remove dissolved oxygen. The liquid temperature was raised to 85°C and maintained at 85°C for 3.5 hours, and then a mixed solution of YUBASE4 (42 parts) and Luperox 575 (0.015 part) was added dropwise over 2 hours. Further, after maintaining at 85°C for 1 hour, a mixed solution composed of YUBASE4 (20 parts) and Luperox 575 (0.5 part) was added dropwise over 1 hour, and then the liquid temperature was raised to 110°C and maintained at 110°C for 1 hour. After adding YUBASE4 (61.1 parts), it was cooled to obtain a YUBASE4 solution containing 35% by mass of the polymer composition. The evaluation results of the obtained polymer composition are shown in Table 4.

[0088] <Example 14> Into a reaction vessel equipped with a stirrer, a cooling pipe, and a thermometer, 6.9 parts of YUBASE4, 47.6 parts of a YUBASE4 solution of the macro monomer M6 obtained in Production Example 7, 52 parts of n-butyl acrylate, 23 parts of lauryl acrylate, 0.015 part of Perbutyl O as a polymerization initiator, and 0.01 part of Nofmer MSD as a chain transfer agent were added. While stirring, nitrogen was bubbled to remove dissolved oxygen. The liquid temperature was raised to 85°C and maintained at 85°C for 2 hours, and then a mixed solution of YUBASE4 (42 parts) and Perbutyl O (0.015 part) was added dropwise over 2 hours. Further, after maintaining at 85°C for 1 hour, a mixed solution composed of YUBASE4 (67.5 parts) and Perocta O (0.5 part) was added, the temperature was raised to 95°C, and the liquid temperature was maintained at 95°C for 1 hour. After adding YUBASE4 (46.7 parts), it was cooled to obtain a YUBASE4 solution containing 35% by mass of the polymer composition. The evaluation results of the obtained polymer composition are shown in Table 4.

[0089] <Example 15> Into a reaction vessel equipped with a stirrer, a cooling pipe, and a thermometer, 30 parts of YUBASE4 and 47.6 parts of a YUBASE4 solution of the macromonomer M6 obtained in Production Example 7 were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85°C, and a mixed solution consisting of YUBASE4 (25 parts), n-butyl acrylate (52 parts), lauryl acrylate (23 parts), and Luperox 575 (0.1 part) as a polymerization initiator was added dropwise over 4 hours. Further, after holding at 85°C for 1 hour, a mixed solution consisting of YUBASE4 (50 parts) and Perox 575 (0.5 part) was added dropwise over 1.5 hours, and the liquid temperature was raised to 110°C. After holding at 110°C for 1 hour, YUBASE4 (58.1 parts) was added and then cooled to obtain a YUBASE4 solution containing 35% by mass of the polymer composition. The evaluation results of the obtained polymer composition are shown in Table 4.

[0090] <Example 16> Into a reaction vessel equipped with a stirrer, a cooling pipe, and a thermometer, 20 parts of YUBASE4 and 46.3 parts of a YUBASE4 solution of the macromonomer M3 obtained in Production Example 4 were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85°C, and a mixed solution consisting of YUBASE4 (25 parts), n-butyl acrylate (30 parts), lauryl acrylate (35 parts), 2-methoxyethyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name: 2-MTA) 10 parts, and Luperox 575 (0.1 part) as a polymerization initiator was added dropwise over 4 hours. Further, after holding at 85°C for 1 hour, a mixed solution consisting of YUBASE4 (60 parts) and Perox 575 (0.5 part) was added dropwise over 1.5 hours, and the liquid temperature was raised to 110°C. After holding at 110°C for 1 hour, YUBASE4 (59.4 parts) was added and then cooled to obtain a YUBASE4 solution containing 35% by mass of the polymer composition. The evaluation results of the obtained polymer composition are shown in Table 4.

[0091] <Examples 4 to 6, 9 to 12 and Comparative Example 1> A polymer composition was obtained in the same manner as in Example 3, except that the types of macro monomers used, the types and amounts of monomers, and the amount of α-methylstyrene dimer were changed to the contents shown in Tables 2 to 5. The evaluation results of the obtained polymer composition are shown in Tables 2 to 5. <Examples 17 and 18> A polymer composition was obtained in the same manner as in Example 16, except that the type of macro monomer used and the types and amounts of monomers were changed to the contents shown in Table 4. The evaluation results of the obtained polymer composition are shown in Table 4. <Comparative Examples 2 to 6> A polymer composition was obtained in the same manner as in Example 1, except that the types and amounts of monomers used and the amount of α-methylstyrene dimer were changed to the contents shown in Table 5. The evaluation results of the obtained polymer composition are shown in Table 5. The viscosity indices of Comparative Examples 1 to 5 decreased.

[0092]

Table 1

[0093]

Table 2

[0094]

Table 3

[0095]

Table 4

[0096]

Table 5

[0097] The abbreviations in Tables 1 to 5 are as follows. ·SLMA: A mixture of alkyl methacrylate with 12 carbon atoms in the alkyl group and alkyl methacrylate with 13 carbon atoms in the alkyl group (manufactured by Mitsubishi Chemical Corporation, trade name: Acryester SL) ·MMA: Methyl methacrylate (manufactured by Mitsubishi Chemical Corporation, trade name: Acryester M) ·EHA: 2-Ethylhexyl acrylate (manufactured by Mitsubishi Chemical Corporation, trade name: 2-Ethylhexyl acrylate) ·Co complex: The cobalt chain transfer agent obtained in Production Example 1 ·α-Methylstyrene dimer (manufactured by NOF Corporation, trade name: Nofmer MSD) ·YUBASE3 (base oil of API Group III specification, manufactured by SK Lubricants Co., Ltd.) ·YUBASE4 (base oil of API Group III Plus specification, manufactured by SK Lubricants Co., Ltd.) ·LA: Lauryl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name: LA) ·BA: n-Butyl acrylate (manufactured by Mitsubishi Chemical Corporation, trade name: Butyl acrylate) ·EA: Ethyl acrylate (manufactured by Mitsubishi Chemical Corporation, trade name: Ethyl acrylate) ·BMA: n-Butyl methacrylate (manufactured by Mitsubishi Chemical Corporation, trade name: Acryester B) ·2-MTA: 2-Methoxyethyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name: 2-MTA)

Industrial Applicability

[0098] According to the present invention, it is possible to provide a polymer composition, a polymer composition, a viscosity index improver, and a lubricating oil composition having a high viscosity index improving effect Also, according to the method for producing the polymer composition of the present invention, a polymer composition having a high viscosity index improving effect can be produced Furthermore, according to the method for producing the macromonomer of the present invention, a macromonomer capable of producing a polymer composition having a high viscosity index improving effect can be produced. A polymer composition can be provided

Claims

1. A method for producing a macromonomer, which comprises polymerizing a monomer mixture containing a vinyl radical-polymerizable monomer using a cobalt chain transfer agent in a base oil, wherein the base oil contains a mineral base oil refined from crude oil or a synthetic oil chemically synthesized, the method for producing a macromonomer.

2. The method for producing a macromonomer according to claim 1, wherein the base oil is a base oil of API Group III or a base oil of API Group III Plus.

3. The method for producing a macromonomer according to claim 1, wherein the vinyl radical-polymerizable monomer is a (meth)acrylate having an alkyl group.

4. The method for producing a macromonomer according to claim 3, wherein the (meth)acrylate having an alkyl group is an alkyl methacrylate a1 having 5 to 14 carbon atoms in the alkyl group.

5. The macromonomer is used for forming a graft copolymer, the graft copolymer is a copolymer containing a structural unit derived from an alkyl methacrylate a1 having 5 to 14 carbon atoms in the alkyl group, a structural unit derived from an alkyl acrylate a2 having 5 to 14 carbon atoms in the alkyl group, and a structural unit derived from an alkyl acrylate a3 having 1 to 4 carbon atoms in the alkyl group, the graft copolymer contains a structural unit derived from a vinyl radical-polymerizable monomer m1 and a structural unit derived from the macromonomer, when a polymer composition containing the graft copolymer is prepared, the differential distribution value in the differential molecular weight distribution curve of the polymer composition measured by gel permeation chromatography satisfies the following formula 1, For the 35 wt% of the following base oil solution of the polymer composition, the magnitude q of the scattering vector of small-angle X-ray scattering at 25 °C is 0.07 nm －１ or more and 2 nm －１ In the following range, the maximum value of the normalized scattering intensity is 40 cm －１ or more. The method for producing a macromonomer according to claim 1 dMp30 / dMp ≧ 0.65 ··· 1 - dMp30: The differential distribution value of the molecular weight corresponding to 30% of the peak top molecular weight measured by gel permeation chromatography. - dMp: The differential distribution value of the peak top molecular weight measured by gel permeation chromatography. - Base oil: API Group III, or Group III Plus.

6. The method for producing a macromonomer according to claim 5, wherein the graft copolymer contains 1 to 50% by mass of the structural unit derived from the alkyl methacrylate a1 based on the total mass of the graft copolymer.

7. The macromonomer is used for forming a graft copolymer, The graft copolymer contains a structural unit derived from a vinyl-based radically polymerizable monomer m1 and a structural unit derived from the macromonomer. The graft copolymer is a copolymer containing a structural unit derived from an alkyl methacrylate a1 having 5 to 14 carbon atoms in the alkyl group, a structural unit derived from an alkyl acrylate a2 having 5 to 14 carbon atoms in the alkyl group, and a structural unit derived from an alkyl acrylate a3 having 1 to 4 carbon atoms in the alkyl group. The method for producing a macromonomer according to claim 1, wherein the graft copolymer contains 1 to 50% by mass of the structural unit derived from the alkyl methacrylate a1 based on the total mass of the graft copolymer.

8. The method for producing a macromonomer according to any one of claims 5 to 7, wherein the graft copolymer contains 1 to 50% by mass of the structural unit derived from the alkyl acrylate a2 based on the total mass of the graft copolymer.

9. The method for producing a macromonomer according to any one of claims 5 to 8, wherein the graft copolymer contains 30 to 80% by mass of the structural unit derived from the alkyl acrylate a3 based on the total mass of the graft copolymer.

10. The method for producing a macromonomer according to any one of claims 5 to 9, wherein the graft copolymer is a copolymer containing a structural unit derived from an alkoxyalkyl (meth)acrylate a4.

11. The method for producing a macromonomer according to claim 10, wherein the graft copolymer contains 1 to 30% by mass of the structural unit derived from the alkoxyalkyl (meth)acrylate a4 based on the total mass of the graft copolymer.

12. The method for producing a macromonomer according to claim 7, wherein the differential distribution value in the differential molecular weight distribution curve measured by gel permeation chromatography satisfies the following formula 1. dMp30 / dMp ≧ 0.65...1 - dMp30: The differential distribution value of the molecular weight corresponding to 30% of the peak top molecular weight. - dMp: The differential distribution value of the peak top molecular weight.

13. When preparing the polymer composition containing the graft copolymer, the magnitude q = 0.1 nm of the scattering vector of small-angle X-ray scattering at 100 °C of a 35 wt% base oil solution of the API standard Group III or Group III plus of the polymer composition －１ The normalized scattering intensity in is 1 cm －１ The method for producing a macromonomer according to claim 7, wherein the above is satisfied.

14. The method for producing a macromonomer according to any one of claims 5 to 13, wherein when a polymer composition containing the graft copolymer is prepared, the mass average molecular weight of the polymer composition measured by gel permeation chromatography is 50,000 to 2,000,000.

15. When preparing the polymer composition containing the graft copolymer, the method for producing a macromonomer according to any one of claims 5 to 14, wherein the molecular weight distribution of the polymer composition measured by gel permeation chromatography is 5 to 20.

16. The method for producing a macromonomer according to any one of claims 5 to 15, wherein the vinyl radical-polymerizable monomer m1 contains the alkyl acrylate a2 and the alkyl acrylate a3.

17. The method for producing a macromonomer according to any one of claims 1 to 16, wherein the macromonomer contains a structural unit derived from a vinyl radical-polymerizable monomer m2.

18. The method for producing a macromonomer according to claim 17, wherein the vinyl radical-polymerizable monomer m2 contains an alkyl methacrylate a1 having 5 to 14 carbon atoms in the alkyl group.

19. The method for producing a macromonomer according to any one of claims 1 to 18, wherein the macromonomer has a structure of the following formula 2. 【Chemical 1】 (In the formula, X １ to X ｎ－１ each independently represents a hydrogen atom, a methyl group, or CH ２ OH, Y １ to Y ｎ each independently represents a substituent bonded to the vinyl group of the vinyl radical polymerizable monomer m2. Z represents a terminal group, and n represents an integer of 2 to 10,000.)

20. The method for producing a macromonomer according to any one of claims 1 to 19, wherein the number average molecular weight of the macromonomer measured by gel permeation chromatography is 500 to 30,000.

21. The method for producing a macromonomer according to any one of claims 5 to 15, wherein when preparing the polymer composition containing the graft copolymer, the polymer composition is for a lubricant additive.

22. The method for producing a macromonomer according to any one of claims 5 to 15 and 21, wherein when preparing the polymer composition containing the graft copolymer, the polymer composition is for a viscosity index improver.

23. The method for producing a macromonomer according to any one of claims 5 to 15, 21 and 22, wherein when preparing the polymer composition containing the graft copolymer, the polymer composition is for a friction modifier.

24. The method for producing a macromonomer according to any one of claims 5 to 15 and 21 to 23, wherein when preparing the polymer composition containing the graft copolymer, the polymer composition is for a lubricant composition.

25. A method for producing a polymer composition by polymerizing a monomer mixture containing a macromonomer and a vinyl radical-polymerizable monomer in a base oil, The method for producing a polymer composition, wherein the macromonomer is produced by the method for producing a macromonomer according to any one of claims 1 to 20.

26. A method for producing a polymer composition according to claim 25, using α-methylstyrene dimer as a chain transfer agent.

27. A method for producing a lubricating oil composition comprising the polymer composition and a base oil, wherein the polymer composition is produced by the method for producing a polymer composition according to claim 25 or 26.

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