JP6507817B2 - Water-based coating agent - Google Patents

Description

The present invention relates to a water-based coating agent. More particularly, the present invention relates to a water-based coating agent effectively applied to the surface of a rubber sealing material or sliding member .

  At present, a seal made of rubber, which is often used, has a phenomenon of sticking to each other or to a contact surface of a mating material such as metal or resin when the device is assembled. As measures against these problems, the incorporation is improved by applying a liquid such as wax, grease or lubricating oil to the sealing material.

  However, for example, in the case of transporting by a parts feeder in order to automatically incorporate rubber parts such as O-rings, if a large amount of these liquids are applied, the coefficient of friction becomes low, but the products are blocked due to stickiness of the applied liquids. Cause problems with the automatic supply of products. On the contrary, when the application of the liquid is reduced to reduce stickiness, the liquid adheres to the periphery and the like, and blocking occurs. These liquids are easy to remove because they are liquids, are not sufficiently sustained, and it is difficult to control the amount of application of the liquids. Therefore, only by using such liquids, it is possible to obtain a stable state of the rubber component. It is difficult to get. On the other hand, when inorganic materials such as graphite, silica, talc and the like are crushed, blocking can be prevented without stickiness, but the falling off causes contamination of the peripheral portion.

(B) CH₂=C(CH₃)COO(CH₂)₃Si(OR¹)nR²m
(C) CH₂=CHCOO(CH₂)₃Si(OR¹)nR²m
(D) H₂N(CH₂)₃Si(OR¹)nR²m
または
(E) H₂NC₂H₄NH(CH₂)₃Si(OR¹)nR²m
(ここで、いずれもR¹およびR²はそれぞれ独立に炭素数が1〜4のアルキル基を示し、nおよびmはそれぞれ1≦n≦3、m=3-nである)で表わされるシラン化合物および／またはその部分加水分解物よりなり、シリコーンオイルの不揮発分重量100重量部に対してポリウレタン樹脂が固形分重量として100重量部以上用いられた水系表面処理剤を提案している(特許文献１)。 In order to solve such problems, the applicant has previously been a mixture of an aqueous emulsion of silicone oil, an aqueous emulsion containing (a) hydrazides and a polyurethane resin containing a carbonyl group, and (b) an aqueous emulsion of silanol modified polyurethane resin. Aqueous emulsion and general formula of polyurethane resin

_{(B) CH 2 = C (} CH 3) COO (CH 2) 3 Si (OR 1) nR 2 m
_{(C) CH 2 = CHCOO (} CH 2) 3 Si (OR 1) nR 2 m
_{(D) H 2 N (CH} 2) 3 Si (OR 1) nR 2 m
Or
_{(E) H 2 NC 2 H} 4 NH (CH 2) 3 Si (OR 1) nR 2 m
(Here, each of R ¹ and R ² independently represents an alkyl group having 1 to 4 carbon atoms, n and m each satisfy 1 ≦ n ≦ 3, m = 3−n) We have proposed a water-based surface treatment agent comprising a compound and / or a partial hydrolyzate thereof, wherein a polyurethane resin is used in an amount of at least 100 parts by weight as solid weight relative to 100 parts by weight of non-volatile content of silicone oil (patent document 1).

  By setting the total amount of polyurethane resin to the same amount or more as the silicone oil content, the water-based surface treatment agent is excellent in durability because the oil does not bleed and adhesion to the substrate is also improved. Since the solvent resistance is also improved, adhesion to rubber materials such as O-rings or metals, resins, etc. is effectively prevented, but further improvement is achieved in terms of tensile strength and tensile modulus. Desired.

Patent No. 5111493 Patent No. 3641690 JP, 2011-212569, A JP, 2012-117019, A JP, 2012-188661, A Unexamined-Japanese-Patent No. 7-233347 JP, 2006-299274, A

An object of the present invention is a water-based coating agent comprising a silanol-modified polyurethane resin as a main component, which provides a water-based coating agent capable of suppressing the amount of wear and improving the heat resistance while maintaining low friction characteristics. It is.
The resin-rubber composite according to 1.

The object of the present invention is to contain a polyurethane resin aqueous dispersion and a cellulose nanofiber aqueous dispersion paste, and the amount of cellulose nanofibers in the total amount of polyurethane resin solid content and cellulose nanofiber solid content is 3 to 17 weight % and is achieved by a rubber sealing material or an aqueous coating agent used in the sliding member, preferably polyurethane resin aqueous dispersion and silanol-modified polyurethane resin aqueous dispersion and the hydrazide and carbonyl group-containing aqueous polyurethane resin dispersion And an aqueous dispersion of silicone oil and a silane compound and / or a partial hydrolyzate thereof.

The water-based coating agent used for the rubber sealing material or sliding member according to the present invention, which is obtained by adding cellulose nanofibers to silanol-modified polyurethane,
(1) A water-dispersed organic resin tends to be inferior in hardness and strength of the film as compared to a resin dissolved in an organic solvent because it contains many hydrophilic functional groups in the polymer skeleton.
(2) When a rubber material or resin material is used as the base material, the upper limit of the baking temperature is as low as about 120 to 150 ° C, and when it is necessary to bake at high temperature, high elastic and high strength rubber or resin is used. Can not do it
(3) As a method to improve the strength and elastic modulus of organic resin, there is a method to improve mechanical properties by filling glass fiber, carbon fiber etc., but these fibers damage the surface of the opposite material and reverse Lower the friction and wear characteristics
(4) With the recent trend of energy saving and low friction, machine parts with a small load tend to be replaced with metal and rubber or resin, but due to the problems (1) to (3) above, rubber and resin parts It is possible to effectively solve the problems that it was difficult to form a solid film lubricant having a sufficient function on the surface of the steel.

  More specifically, while maintaining low friction, tensile strength and tensile elastic modulus are significantly improved, and even when heated to a temperature near the glass transition temperature Tg, which is generally the heat resistance limit of thermoplastic resins, a film Can suppress the softening of the steel and maintain its characteristics without breaking even under load.

The water-based coating agent of the present invention having such characteristics is not only effectively applied to rubber sealing materials such as O-rings, oil seals, packings, and gaskets, but also sliding parts of resin cages of bearings, sliders, Sliding member of ball screw, inner and outer diameter of sliding bearing made of resin, gear parts, weather strip, sliding rubber for automobile such as wiper blade, rubber sliding member such as rubber material for office equipment such as toner blade, rubber roll etc Is also applied effectively.

このシロキサン結合は、他のウレタン化架橋反応で生成する結合に比べ安定であるため、得られる表面処理被膜の耐溶剤性が良好であるといった効果を奏する。ウレタン樹脂水性分散液は、表面処理被膜に摺動に対する耐久性を与え、さらにシリコーンオイルを取り込み、表面処理被膜にオイル分をブリードさせることなく、潤滑性、低摩擦性、非粘着性を与える。かかるシラノール変性ポリウレタン樹脂水性分散液としては、樹脂固形分濃度10〜70重量％のものが用いられる。 The silanol-modified polyurethane resin aqueous dispersion is an aqueous dispersion containing silanol groups in the polyurethane structure, and the silanol groups are crosslinked by condensation reaction to form siloxane bonds.

Since this siloxane bond is more stable than bonds generated by other urethanization crosslinking reaction, it has an effect that the solvent resistance of the surface-treated film obtained is good. The urethane resin aqueous dispersion imparts durability to sliding on the surface treatment film, further incorporates silicone oil, and imparts lubricity, low friction and non-adhesiveness without bleeding the oil on the surface treatment film. As such a silanol modified polyurethane resin aqueous dispersion, one having a resin solid concentration of 10 to 70% by weight is used.

  Cellulose nanofibers (CNF) are described, for example, in Patent Document 2, and are obtained by finely disaggregating plant fibers to nanosize with the skeletal components of all plant cell walls. As vegetable fibers, not only wood but also rice straw, sugar cane pomace, sugar radish pomace, potato pomace, cassava pomace, etc. may be used.

  The fine structure of the tree cell wall is composed of CNF 50%, hemicellulose 20-30%, lignin 20-30%, and has a structure in which CNF is embedded in lignin. CNF obtained by loosening such plant fibers to nano size by mechanical disintegration etc. has a width of 4 to 100 nm, a length of 5 μm or more, a high aspect ratio, and a central three-point support at room temperature and 60% RH It is considered to be a high strength material having a bending strength of 200 to 400 MPa by the concentrated load method.

  In the present invention, cellulose nanofibers which are CNFs such as CNF used as a water dispersion paste having a concentration of about 0.1 to 15% by weight, preferably 7 to 13% by weight, or a CNF derivative thereof such as carboxyl group-containing CNF (Patent Document 3) Is used in a proportion of 3 to 17% by weight, preferably 5 to 17% by weight in the total amount with the polyurethane resin (silanol modified + hydrazide and containing a carbonyl group). By using CNF at such a ratio, tensile strength and tensile modulus can be significantly improved. When used in a smaller proportion, these improvements can not be achieved, while when used more than this, the tensile modulus is improved, but the tensile strength is not improved, and the durability is improved. Lowers, the substrate becomes exposed, and the heat resistance breaks at room temperature.

  In addition, although it is described in patent documents 4-5 that CNF is used as functional fillers, such as gas barrier property, they are only a statement.

Aqueous dispersions containing hydrazides and a carbonyl group-containing polyurethane resin include aqueous dispersions of hydrazides and a carbonyl group-containing polyurethane-vinyl hybrid polymer as described in Patent Documents 6-7. It is crosslinked by the azomethine bond obtained by reaction of hydrazides with the carbonyl group of the polyurethane-vinyl-hybrid polymer. In this case, in general, these two compounds are used in such a ratio that the ratio of the number of hydrazine groups to the number of carbonyl groups is 1:40 to 2: 1.

  Hydrazides include hydrazine, a low molecular weight aliphatic compound having a hydrazide group and / or a hydrazone group, an aromatic compound or a mixture thereof, and a polyhydrazide having at least two or more of these groups and a polyvalent compound Hydrazide compounds are also used. Also, the polyurethane-vinyl-hybrid polymers can be ion- and / or non-ion-stabilized polyurethane macros having terminal vinyl groups and / or side-chain vinyl groups and optionally terminal hydroxyl groups, urethane groups, thiourethane groups or urea groups. The monomers are prepared by free radical initiated polymerization with other functional vinyl monomers containing a carbonyl group as well as nonfunctional vinyl monomers. As such an aqueous dispersion, as described in Patent Document 2, Daoxan VTW 6462 / 36WA, which is a commercially available product, is actually used, or other Daotan series etc. are used.

  The hydrazides and the carbonyl group-containing polyurethane resin are used in a proportion of about 0.1 to 20 parts by weight, preferably about 2 to 18 parts by weight, per 100 parts by weight of the silanol-modified polyurethane resin. If it is used at a ratio higher than this, the solvent resistance tends to be lowered.

As the silicone oil, an organopolysiloxane having at least one organic group bonded to a silicon atom with a kinematic viscosity at 25 ° C. of 50 to 1,000,000 mm ² / sec, preferably 500 to 200,000 mm ² / sec is used. The molecular structure may be linear, branched or network, preferably linear or branched, more preferably linear. The organic group bonded to the silicon atom in the organopolysiloxane is an alkyl group such as methyl group, ethyl group, propyl group, butyl group or hexyl group, an alkenyl group such as vinyl group or propenyl group, or a phenyl group. Examples thereof include aralkyl groups such as aryl groups and phenethyl groups, and those in which part of the hydrogen atoms of these hydrocarbon groups are substituted with halogen atoms, nitrile groups and the like. Examples of the terminal organic group of the organopolysiloxane include methyl group, amino group, epoxy group, carbinol group, hydroxyl group, methoxy group, methacryloxy group, carboxyl group, silanol group, alkoxy group and the like, with preference given to carbinol group and hydroxyl group And methoxy. Silicone oils impart lubricity, low friction, and non-stickiness to surface treatment coatings.

  Moreover, as aqueous dispersions using these silicone oils, in addition to hydrophilic silicone oil aqueous dispersions, forced emulsification silicone oil aqueous dispersions using emulsifiers can also be used, and the dispersion method is not particularly limited. . As such a silicone oil aqueous dispersion, one having a silicone oil content (nonvolatile content) of 3 to 60% by weight is used.

  The aqueous dispersion of silicone oil is used as silicone oil non volatile matter in a proportion of about 3 to 30 parts by weight, preferably about 5 to 25 parts by weight, per 100 parts by weight of the silanol modified polyurethane resin. If the proportion is less than this range, the low friction property can not be exhibited due to insufficient lubrication, while if the proportion is more than this range, the strength of the film is reduced and the wear and abrasion characteristics are significantly reduced.

(B) CH₂=C(CH₃)COO(CH₂)₃Si(OR¹)nR²m
(C) CH₂=CHCOO(CH₂)₃Si(OR¹)nR²m
(D) H₂N(CH₂)₃Si(OR¹)nR²m
または
(E) H₂NC₂H₄NH(CH₂)₃Si(OR¹)nR²m
(R¹、R²：炭素数が1〜4のアルキル基、n、m：1≦n≦3、m=3-n)で表わされるシラン化合物が用いられる。これらは、シリコーンエマルジョンの反応性有機基、上記特定のシラン化合物のアルコキシ基との反応により、表面処理被膜内にシリコーンオイルを保持させ、オイル分をブリードさせることなく、表面の潤滑性、低摩擦性、非粘着性を発現させる成分であり、ポリウレタン樹脂の水性分散液と反応し、シリコーンオイルと架橋後のポリウレタン樹脂の親和性を向上させ、シリコーンオイルを表面処理被膜内にとどめる効果を奏する。また、表面処理させる基材に対し、塗装性の向上を付与させる働きを有する。 As a silane compound, a general formula

_{(B) CH 2 = C (} CH 3) COO (CH 2) 3 Si (OR 1) nR 2 m
_{(C) CH 2 = CHCOO (} CH 2) 3 Si (OR 1) nR 2 m
_{(D) H 2 N (CH} 2) 3 Si (OR 1) nR 2 m
Or
_{(E) H 2 NC 2 H} 4 NH (CH 2) 3 Si (OR 1) nR 2 m
A silane compound represented by (R ¹ , R ² : alkyl group having 1 to 4 carbon atoms, n, m: 1 ≦ n ≦ 3, m = 3−n) is used. These allow the silicone oil to be retained in the surface treatment film by the reaction with the reactive organic group of the silicone emulsion and the alkoxy group of the above specific silane compound, and the surface lubricity, low friction, without bleeding the oil component. It is a component that develops the property of tackiness and non-stickiness, reacts with the aqueous dispersion of the polyurethane resin, improves the affinity of the silicone oil and the polyurethane resin after crosslinking, and has the effect of retaining the silicone oil in the surface treatment film. In addition, it has the function of imparting the improvement of the paintability to the base material to be surface-treated.

As such a silane compound, for example, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltripropoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropyltrimethoxysilane Cidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyldipropoxysilane (more than silane compound A), γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropyltripropoxysilane Silane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropylmethyldipropoxysilane (more than silane compound B), 3-acryloxypropylmethyldimethoxysilane, 3-a Cryloxypropylmethyldiethoxysilane, 3-acryloxypropyltriethoxysilane (more than silane compound C), 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane (more than silane compound D), N-2- ( Aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropyltriethoxysilane, 3- (2 -Aminoethyl) aminopropylmethyldimethoxysilane (more than silane compound E) and the like, preferably γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane Γ-methacryloxypropylmethyldimethoxysilane or the like is used.

  Partial hydrolysis products of these silane compounds can also be used. The hydrolyzate can be obtained by subjecting one or more mixtures of silane compounds to a condensation reaction under hydrolysis conditions depending on the type of silane compound.

  It is preferable to mix | blend a silane compound in the ratio of 10-60 weight part with respect to 100 weight part of oil components (non volatile matter) of silicone oil aqueous dispersion liquid. When the silane compound is used in a higher proportion, the coefficient of friction is increased and the durability is decreased, while when it is used in a lower proportion, excessive bleeding of oil is generated.

  In the water-based coating agent comprising the above each essential component, an amphoteric surfactant such as an alkylamine oxide compound or an alkyl betaine in order to prevent a coating liquid and prevent coating unevenness and a coating amount shortage. Can also be blended. Examples of alkylamine oxide compounds include dimethylalkylamine oxide and the like, and alkylbetaines include alkyldimethylaminoacetic acid betaine. Examples of the alkyl group include lauryl group, myristyl group, natural fat and oil modifying groups such as coconut oil, etc. Is illustrated. The compounding amount of the alkylamine oxide compound and the alkylbetaine is used so as to be within 10% by weight with respect to the total amount of the composition.

  The water-based coating agent may further contain an antifoaming agent, a pigment, an inorganic powder, a thickener, a surfactant and the like as necessary, and the preparation of the composition is effective from the viewpoint of coating efficiency and coatability. The ingredients are diluted with water to a concentration of 0.1 to 40% by weight and used. Each of these compounding ingredients is mixed and used after being sufficiently stirred and emulsified. The mixing is carried out using a known mixing paddle equipped with stirring blades such as paddle type or bowl type, combimix, etc., and the emulsification treatment is an emulsion dispersing apparatus such as a colloid mill, homomixer, homogenizer, combimix or sand grinder. It is done using

  The prepared aqueous coating agent is applied to the surface of the member to be treated by a method such as dipping, brush coating, roll coating, spray coating, knife coating, dip coating, etc. The surface treatment is carried out by heating and drying for 60 minutes to form a cured film.

The water-based coating agent of the present invention is a water-based sealing material or sliding member made of a rubber seal material such as fluorine rubber, NBR, hydrogenated NBR, SBR, isoprene rubber, butadiene rubber, chloroprene rubber, acrylic rubber, EPDM, urethane rubber, silicone rubber, etc. It is effectively used as a coating agent.

  The invention will now be described by way of example.

Comparative Example 1
Preparation of the water-based coating agent was performed using the following components. In addition, the usage-amount has shown the weight part as solid content.
Silanol-modified PU (Tg: 135 ° C.) aqueous emulsion 80 parts by weight
(Mitsui Chemicals Takelac WS-4000, concentration 30% by weight)
Hydrazide / Carbonyl group-containing PU aqueous emulsion 7
(Allex product Daoton VTW 6462/36 W, concentration 36% by weight)
Both terminal hydroxyl group modified silicone oil aqueous emulsion 11.2
(Momentive Performance Materials Japan Co., Ltd. product, concentration 33% by weight)
γ-Glycidoxypropyltrimethoxysilane 1.8 〃
(Product of the company)

Example 1
In Comparative Example 1, the amount of silanol-modified PU aqueous emulsion is changed to 76 parts by weight, and 4 parts by weight of cellulose nanofiber [CNF] water dispersion paste (middle-aged pulp industrial product LB-CNF 10C, concentration 10% by weight) is used The The total weight of PU (Takelac + Daoton): CNF weight ratio was 95.4: 4.6. In addition, a bead mill was used to disperse the CNF aqueous paste in the aqueous coating agent.

Example 2
In Comparative Example 1, the amount of silanol modified PU aqueous emulsion was changed to 72 parts by weight, and 8 parts by weight of a cellulose nanofiber [CNF] water dispersion paste (LB-CNF 10C) was used. The total weight of PU (Takelac + Daoton): CNF weight ratio was 90.8: 9.2.

Example 3
In Comparative Example 1, the amount of silanol-modified PU aqueous emulsion was changed to 68 parts by weight, and 12 parts by weight of cellulose nanofiber [CNF] water dispersion paste (LB-CNF 10C) was used. The total weight of PU (Takelac + Daoton): CNF weight ratio was 86.2: 13.8.

Example 4
In Comparative Example 1, the amount of silanol modified PU aqueous emulsion was changed to 66 parts by weight, and 14 parts by weight of cellulose nanofiber [CNF] water dispersion paste (LB-CNF 10C) was used. The total weight of PU (Takelac + Daoton): CNF weight ratio was 83.9: 16.1.

Comparative example 2
In Comparative Example 1, the amount of silanol modified PU aqueous emulsion was changed to 64 parts by weight, and 16 parts by weight of a cellulose nanofiber [CNF] water dispersion paste (LB-CNF 10C) was used. The total weight of PU (Takelac + Daoton): CNF weight ratio was 81.6: 18.4.

Comparative example 3
In Comparative Example 1, the amount of silanol-modified PU aqueous emulsion was changed to 56 parts by weight, and 24 parts by weight of cellulose nanofiber [CNF] water dispersion paste (LB-CNF 10C) was used. The total weight of PU (Takelac + Daoton): CNF weight ratio was 72.4: 27.6.

Comparative example 4
In Comparative Example 1, as a silanol-modified PU aqueous emulsion, an aqueous emulsion (Mitsui Chemical Polyurethane Products Takelac WS-5000, solid content concentration 30% by weight) is the same amount (solid content) as the glass transition temperature Tg of silanol-modified PU is 65 ° C. 80 parts by weight) was used.

The following items were tested for each of the above water-based coating agents.
・ Tensile strength, tensile modulus: Tester: Shimadzu EZ-500N
Dumbbell shape: No. 5 dumbbell (118 x 25 mm)
Test piece coating thickness: 50 μm
N number: 5
・ Dynamic coefficient of friction
A sliding test was carried out under the following conditions for a test piece of A6061-T6 treated plate coated with an aqueous coating agent at a film thickness of about 10 to 20 μm, and the dynamic friction coefficient was measured. Upper test piece: 10 mm diameter SUS ball Load: 100 g (0.98 N)
Speed: 1000 mm / min (0.017 m / sec)
Amplitude: 30 mm
Temperature: 25 ° C
Number of times: 100 round trips (calculated as the average value of 100 round trips)
·durability
The durability of the coated film is evaluated for the test piece of A6061-T6 treated plate coated with the aqueous coating agent at a film thickness of about 10 to 20 μm Upper test piece: 10 mm diameter SUS ball Load: 300 g (2.94 N)
Speed: 1000 mm / min (0.017 m / sec)
Amplitude: 20 mm
Temperature: 25 ° C
Judgment: The number of times the film is worn or broken, peeled, and the substrate exposed is taken as the number of endurance times
Also, no problem is evaluated as ○, substrate exposure is evaluated as × · Heat resistance
Evaluation of the heat resistance of the coating film on the test piece of A6061-T6 treated plate coated with aqueous coating agent in film thickness of about 10 to 20 μm Upper test piece: 10 mm diameter SUS ball Load: 300 g (2.94 N)
Speed: 1000 mm / min (0.017 m / sec)
Amplitude: 20 mm
Temperature: 25 ° C, 40 ° C, 60 ° C, 80 ° C, 100 ° C, 120 ° C, 140 ° C
Judgment: Starting from 25 ° C., the coating wears or breaks, peels after reciprocation of 1000 times, substrate
If not exposed, test at the next temperature
If the coating wears or breaks, peels off within 1000 cycles, and the substrate is exposed, 1
Judged that the previous temperature condition is the heat-resistant temperature · Comprehensive evaluation Compared with Comparative Example 1 without filling with cellulose nanofibers [CNF], those with improvements in both mechanical properties and heat-resistance properties are ○, Those that only improved on one side were evaluated as △, and those that both decreased on the other side were evaluated as x

The results obtained are shown in the following table.
table
Comparative Example Comparative Example
Measurement item example 1 1 2 3 4 2 3 4
Tensile strength (MPa) 27 33 37 29 29 26 26 13
Tensile modulus (GPa) 0.45 0.55 0.59 0.60 0.77 0.73 0.93 0.05
Dynamic friction coefficient 0.08 0.08 0.07 0.07 0.08 0.07 0.07 0.11
durability
Number of times (times) 1000 1000 1000 1000 1000 900 800 100
Judgment ○ ○ ○ ○ ○ × × × ×
Heat-resistant
Heat resistant temperature (° C) 120 120 140 140 140 25 25 60
Overall evaluation-○ ○ ○ ○ × × ×

Claims (11)

A rubber sealing material comprising a polyurethane resin aqueous dispersion and a cellulose nanofiber aqueous dispersion paste, wherein the amount of cellulose nanofibers in the total amount of the polyurethane resin solid content and the cellulose nanofiber solid content is 3 to 17% by weight Or water-based coating agents used for sliding members .   The water-based coating agent according to claim 1, wherein the polyurethane resin aqueous dispersion is a mixture of a silanol modified polyurethane resin aqueous dispersion and a hydrazide and a carbonyl group-containing polyurethane resin aqueous dispersion.   The water-based coating agent according to claim 2, further comprising an aqueous dispersion of silicone oil and a silane compound and / or a partial hydrolyzate thereof. Silane compounds have the general formula

_{(B) CH 2 = C (} CH 3) COO (CH 2) 3 Si (OR 1) nR 2 m
_{(C) CH 2 = CHCOO (} CH 2) 3 Si (OR 1) nR 2 m
_{(D) H 2 N (CH} 2) 3 Si (OR 1) nR 2 m
Or
_{(E) H 2 NC 2 H} 4 NH (CH 2) 3 Si (OR 1) nR 2 m
(Wherein each of R ¹ and R ² independently represents an alkyl group having 1 to 4 carbon atoms, n and m each represent 1 ≦ n ≦ 3 and m = 3−n) The water-based coating agent according to claim 3, which is   The water based coating agent according to claim 2, wherein the hydrazide and the carbonyl group-containing polyurethane resin is used in a proportion of 0.1 to 20 parts by weight per 100 parts by weight of the silanol modified polyurethane resin.   The water-based coating agent according to claim 3, wherein the silicone oil is used as a non-volatile component in a proportion of 3 to 30 parts by weight per 100 parts by weight of the silanol-modified polyurethane resin.   The water-based coating agent according to claim 3, wherein the silane compound and / or the hydrolyzate thereof is used in a proportion of 10 to 60 parts by weight per 100 parts by weight of the non-volatile content of silicone oil. The water-based coating agent according to claim 1, which is applied to the surface of a rubber sealing material . A rubber sealing material surface-treated with the water-based coating agent according to claim 8. The water-based coating agent according to claim 1, which is applied to the surface of a rubber sliding member. A rubber sliding member surface-treated with the water-based coating agent according to claim 10.