Water-based lubricant

Abstract

To provide a water-based lubricant with good lubricity.SOLUTION: The water-based lubricant contains polyglycerin, which has an average surface coefficient of friction (MIU) of 0.93 or less in a 10% aqueous solution.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an aqueous lubricant containing polyglycerin.

Background Art

[0002] Lubricants are used to reduce friction between substances and are roughly classified into liquid lubricants, semi-solid lubricants, and solid lubricants. Among liquid lubricants, aqueous lubricants are highly regarded because of their high safety, low environmental impact, and non-flammability.

[0003] For example, Patent Document 1 discloses an aqueous lubricant containing an oligomer ester synthesized from (A) one or more divalent carboxylic acids having a linear, branched, or cyclic structure with 2 to 36 carbon atoms and (B) polyglycerin having an average degree of polymerization calculated from the hydroxyl value of 2 to 15. Patent Document 2 discloses a lubricant composition for cutting fiber-reinforced composites, which contains at least one selected from salts of fatty acids having 8 to 22 carbon atoms, salts of partial condensates of fatty acids having 8 to 22 carbon atoms, esterified products of fatty acids having 8 to 22 carbon atoms, esterified products of partial condensates of fatty acids having 8 to 22 carbon atoms, salts of sulfurized fatty acids having 8 to 22 carbon atoms, salts of partial condensates of sulfurized fatty acids having 8 to 22 carbon atoms, esterified products of sulfurized fatty acids having 8 to 22 carbon atoms, and esterified products of partial condensates of sulfurized fatty acids having 8 to 22 carbon atoms.

[0004] As lubricants for the skin, there are those mainly composed of poly-γ-glutamic acid (Patent Document 3) and those containing sodium polyacrylate powder and water (Patent Document 4), which are described as exhibiting appropriate viscosity and lubricity and being able to improve the workability of massage.

[0005] In recent years, glycerin has attracted attention as an environmentally friendly lubricant. Non-Patent Document 1 shows that it has the effect of reducing the dynamic friction coefficient between metals, and its application as a base oil for lubricating oils such as hydraulic oils, gear oils, and bearing oils is also expected.

[0006] In addition, medical lubricants containing glycerin are commercially available and are used as highly safe preparations during endoscopy and catheterization. Furthermore, Patent Document 5 discloses an aqueous lubricant containing water, trehalose, and a water-soluble polymer, which suppresses evaporation and improves taste.

[0007] As described above, aqueous lubricants are used as cutting, grinding, wire drawing of metals and fiber-reinforced composite materials, and hydraulic fluid. In addition, in pharmaceutical applications, there are various uses such as being incorporated into ointments and lotions used during endoscopy and catheterization, and there is a demand for aqueous lubricants that can further improve lubricity.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] The problem to be solved by the present invention is to provide an aqueous lubricant having good lubricity.

Means for Solving the Problems

[0010] As a result of intensive studies to solve the above problems, the present inventors have found that an aqueous lubricant excellent in lubricity can be obtained by blending a specific polyglycerin, and have completed the present invention.

[0011] That is, the present invention provides a water-soluble lubricant containing polyglycerin, a metalworking fluid, a cosmetic, and a skin external preparation, which are characterized in that the average surface friction coefficient (MIU) in a 10% aqueous solution is 0.93 or less.

Effects of the Invention

[0012] The present invention can provide an aqueous lubricant excellent in lubricity and can be used as a lubricant for various applications such as metalworking fluids and cosmetics.

Modes for Carrying Out the Invention

[0013] The present invention will be described in detail below. The scope of the present invention is not limited to this embodiment, and forms in which changes and the like are made without impairing the gist of the present invention also belong to the present invention. Note that "~" representing a range includes the upper and lower limits.

[0014] The polyglycerin according to the present invention can be obtained by a dehydration condensation reaction of glycerin, synthesis using glycerin-related substances such as glycidol, epichlorohydrin, and glycerin halohydrin, or recovery from the glycerin distillation residue of synthetic glycerin. Among them, a general method is to add a small amount of an alkali catalyst to glycerin, heat it to a high temperature of 200 °C or higher, and carry out polycondensation while removing the generated water. The reaction produces successively higher polymers by sequential intermolecular dehydration reactions, resulting in a complex mixture composition of unreacted glycerin, diglycerin, triglycerin, tetraglycerin, and the like. From this, unreacted glycerin and diglycerin are removed by distillation, and then the polyglycerin is distilled, and the polyglycerin of the target composition is obtained by a method such as collecting the distillate.

[0015] The polyglycerol according to the present invention is characterized in that the average surface friction coefficient (MIU) in a 10% aqueous solution is 0.93 or less. Polyglycerol with MIU in this range can impart a smooth feeling to the applied substance and improve lubricity. Furthermore, polyglycerol with an average deviation (MMD) of the average friction coefficient in a 10% aqueous solution of 0.0135 or less is preferable because it is also excellent in smoothness.

[0016] MIU represents the degree of friction generated at the contact surface between the object and the sensor. The lower the numerical value, the less friction and the higher the lubricity. MMD means that the lower the numerical value, the less the variation in MIU, and it can be said to be a smooth state with little roughness. By evaluating the influence of the type of lubricant on MIU and MMD between the object and the center, it is possible to compare the friction reduction effect and the smoothness improvement effect.

[0017] The polyglycerol used in the present invention is preferably contained in an amount of 0.1 to 20% by weight, more preferably 5 to 17% by weight, based on the total amount of cosmetics, external preparations, and metalworking fluids.

[0018] Cosmetics, external preparations, and metalworking fluids containing the aqueous lubricant according to the present invention preferably contain one or more polyhydric alcohols having a valency of 3 or less other than polyglycerol. The polyhydric alcohol having a valency of 3 or less is not particularly limited, and examples thereof include glycerin, dipropylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,2-propylene glycol, 1,3-propanediol, and polyethylene glycol. The content of the polyhydric alcohol having a valency of 3 or less is preferably 0.1 to 20% by weight based on the total amount of cosmetics, external preparations, and metalworking fluids.

[0019] In addition, it can contain components used in lubricants, cosmetics, and external preparations for metal and fiber composite materials without impairing the effects of the invention. For example, as components formulated in lubricants for metal and fiber composite materials, water, preservatives, extreme pressure agents, corrosion inhibitors, rust preventives, lubricating additives, pH adjusters, sequestering agents, surfactants, solvents, thickeners, antioxidants, defoamers, colorants, etc. can be formulated. As components formulated in cosmetics and external preparations, water, oily components, ultraviolet absorbers, ultraviolet scattering agents, surfactants, organic powders, inorganic powders, chelating agents, preservatives, skin lightening agents, vitamins, plant extracts, fragrances, essential oils, pH adjusters, etc. can be formulated.

[0020] The aqueous lubricant of the present invention can be used as a processing fluid for cutting, grinding, wire drawing, etc. of metal and fiber composite materials, and as its dosage form, any dosage form including an emulsified type such as O / W type and a solubilized type can be used.

[0021] The aqueous lubricant of the present invention can be used as cosmetics and external preparations. The specific dosage form is not particularly limited. For example, as cosmetics, cleansing creams, cleansing milks, cleansing lotions, cleansing liquids, facial cleansing creams, facial cleansing foams, massage creams, cold creams, skin creams, skin gels, emulsions, lotions, packs, beauty essences, after-shaving lotions, etc. for skin care cosmetics, sunscreen agents, body shampoos, soaps, body lotions, body creams, bath agents, hand creams, etc. for body care cosmetics, foundations, makeup bases, eye shadows, eyeliners, mascaras, blushes, face powders, eyebrow pencils, etc. for makeup cosmetics, hair shampoos, hair rinses, conditioners, treatments, hair liquids, hair tonics, hair lotions, hair creams, hair dyes, hair styling agents, etc. for hair cosmetics, etc. Also, as external preparations, it can be applied to various ointments, pharmaceuticals such as hair growth agents, toothpastes, disinfectants, and quasi-drugs.

[0022] The aqueous lubricant of the present invention can be used for medical purposes. Specifically, it can be preferably used as a medical lubricating jelly, and is not particularly limited as long as it is used in medical procedures. For example, it is preferably used in endoscopy, barium enema X-ray examination, lubrication assistance in the fields of gynecology and urology, digital rectal examination or enema. Specifically, for example, in endoscopy, the medical lubricant of the present invention can be applied to the surface of the endoscope insertion part for use.

Examples

[0023] Hereinafter, the invention will be described more specifically by way of examples and comparative examples, but the present invention is not limited by these examples.

[0024] The polyglycerin used is described below. Polyglycerin 1 (Product name: Diglycerin S, manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.) Polyglycerin 2 (Product name: PGL-S, manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.) Polyglycerin 3 (Product name: #750, manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.)

[0025] (Measurement of MIU and MMD) A 10% aqueous solution of the polyol shown in Table 1 was prepared, and MIU and MMD were measured by the following method. The measurement results are shown in Table 1.

[0026] Using a friction sensation tester (SURFACE TESTER KES-SE-STP, KATO TECH), the average friction coefficient MIU and its average deviation MMD with respect to a urethane BIO SKIN PLATE (No.64 #BSC urethane plate, BEAULAX Co., Ltd) were measured. A silicon sensor was used for the measurement, the sensitivity (SENS) was H, and the measurement speed was 2 mm / sec. The BIO SKIN PLATE used was one that had been immersed in purified water for 1 hour or more in advance. MIU was calculated by multiplying the integral value of the average friction coefficient when the sensor moved 20 mm by the load coefficient and the coefficient based on the measurement speed. MMD was also calculated in the same manner by multiplying the integral value of the average deviation by the load coefficient and the coefficient based on the measurement speed.

[0027]

Table 1

[0028] Next, skin lotions of Examples 1 to 4 and Comparative Examples 1 to 3 were prepared with the formulations shown in Table 2.

[0029] [Slipperiness in skin lotion] The score of the sample with the best slipperiness after application was set as 5, and the score of the worst sample was set as 1 for relative evaluation. The average score of 20 people was calculated and evaluated according to the following criteria. The results are shown in Table 2. (Evaluation criteria) ○: 4.0 points or more (excellent) △: 3.0 points or more and less than 4.0 points (slightly bad) ×: Less than 3.0 points (bad)

[0030]

Table 2

[0031] The skin lotions of Examples 1 to 4 using the polyglycerin according to the present invention were excellent in slipperiness. On the other hand, the slipperiness of the skin lotions of Comparative Examples 1 to 3 using polyglycerin 3, PEG-400, and glycerin with a MIU greater than 0.93 was not satisfactory compared to the skin lotions of Examples 1 to 4.

[0032] [Lubricity in metalworking fluid] A metalworking fluid was prepared with the formulation shown below. Component Dosage (wt%) Polyglycerin 2 (PGL-S) 12.0 Ethylene glycol 25.0 Sodium oleate 10.0 Triethanolamine 5.0 Morpholine 0.5 Silicone 0.5 Water Balance ――――――――――――――――――――― 100.0

[0033] The metalworking fluid using polyglycerin according to the present invention is excellent in lubricity, and since it is aqueous, it has high safety and low environmental impact.

Claims

**Claim 1** An aqueous lubricant containing polyglycerin, characterized in that the average surface friction coefficient (MIU) in a 10% aqueous solution is 0.93 or less. **Claim 2** The aqueous lubricant containing polyglycerin according to Claim 1, characterized in that the average deviation (MMD) of the average friction coefficient in a 10% aqueous solution is 0.0135 or less. **Claim 3** A metalworking fluid containing the aqueous lubricant according to any one of Claim 1 or Claim 2. **Claim 4** Cosmetics and external skin preparations containing the aqueous lubricant according to any one of Claim 1 or Claim 2. **Claim 5** A medical lubricant containing the aqueous lubricant according to any one of Claim 1 or Claim 2.

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