JPH09290145A - Oil-containing microcapsule, manufacture thereof, and microcapsule-mixed resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide microcapsules which are easy to be handled, cause no trouble due to oil separation at the time of molding, have excellent formability, and have excellent oil retainability, and whose oil exudation in a sliding interface is properly suppressed and to provide a method for manufacturing the microcapsules. SOLUTION: These oil-containing microcapsules are manufactured by coating dew drops of a liquid-phase lubricating oil with three dimensional urethane polymer film produced by producing a hydrophobic liquid body containing an aromatic polyvalent isocyanate, an aliphatic polyvalent isocyanate, and the liquid-phase lubricating oil, emulsifying and dispersing the hydrophobic liquid in a hydrophilic liquid, adding a polyhydric alcohol and a cross-linking agent to the hydrophilic liquid, and simultaneously promoting a polymerization reaction and a cross-linking reaction on the surface of the dew drops of the hydrophobic liquid. A microcapsules mixed synthetic resin composition is provided by mixing the obtained microcapsules to a polyurethane elastomer.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an oil-containing microcapsule obtained by coating a liquid lubricating oil with a three-dimensional urethane polymer film, a method for producing the same, and a resin composition containing the oil-containing microcapsule.

[0002]

2. Description of the Related Art Conventionally, various methods of adding lubricating oil have been known in order to improve the friction and wear characteristics of synthetic resins. For example, a method of using an organic / inorganic powder having a large specific surface area as an oil holding carrier and absorbing a lubricating oil into the powder to disperse it in a base resin (Japanese Patent Publication No. Sho 48-37572, No. 53-11018, etc.), or a lubricating oil The method is to disperse microporous beads that have absorbed into a base resin (Japanese Patent Publication No. 7-91454).

However, in these methods, since the lubricating oil is dispersed in the base resin while being held by the oil holding carrier or the oil holding agent, it is difficult for the lubricating oil to migrate to the sliding interface, and under severe operating conditions. However, the lubricity is still insufficient, the oil is depleted within a relatively short period of time, and the lubrication effect is lacking in sustainability. The bite into the screw is bad,
There are problems such as difficulty in molding.

Further, a resin composition in which a solid lubricant is dispersed in a base resin is used. Examples of solid lubricants include graphite, molybdenum disulfide, and polytetrafluoroethylene (PTFE), and examples of base resins include polyurethane elastomers. For example, it is a resin composition in which about 5% by weight of PTFE pulverized to several tens of microns is dispersed in a polyurethane elastomer. However,
Many solid lubricants are black, and if the color of the object is something other than black, the choices are limited. Those compounded with PTFE make noise due to friction with other articles (so-called "squeaking").
And the friction coefficient is rather large, and the amount of wear increases as the load increases.

In order to solve the above-mentioned various problems in the prior art, by adding oil-containing microcapsules in which a lubricating oil is coated with a thin film of a polymer substance to a base resin, there is no trouble due to oil separation during molding, There has been proposed an oil-containing resin composition for sliding, which has good oil leaching at the sliding interface of the product and good oil retention (Japanese Patent Laid-Open No. 1-129067).

[0006] However, in this proposal, the microcapsules must not be destroyed by the mixing shearing force when adding and dispersing them in the base resin or the heat during processing, but the specific technical contents It is poorly disclosed, for example, when a polyacetal resin having a processing temperature of 170 to 190 ° C. is used as the base resin, it is only described that the urea thermosetting resin is suitable as the wall material of the microcapsules. The detailed technical contents such as the synthesis method are not disclosed therein.

On the other hand, in the field of microcapsules for pressure-sensitive copying paper, complex coacervation method, simple coacervation method, interfacial polycondensation method, in-situ
Microcapsule manufacturing methods such as u polymerization are known. Among these techniques is a method for producing microcapsules in which the wall material is polyurethane (Japanese Patent Laid-Open No. 57-1).
40638, ibid. 58-3898, etc.). In each of these, a hydrophobic liquid containing an aromatic polyvalent isocyanate represented by the structural formula 1 and an aliphatic polyvalent isocyanate is emulsified and dispersed in a hydrophilic liquid, and a polymer substance is obtained by an interfacial polymerization method. It is generated and covers the hydrophobic droplets.

[Chemical 1]

The present inventors have tried to apply the above-mentioned method for producing microcapsules for pressure-sensitive copying paper, in which the wall material is polyurethane, to the production of lubricating oil-containing microcapsules. However, the oil-containing microcapsules obtained are
It has been found that molding is difficult because biting into the screw of the molding machine is poor and the oil is separated because it is broken by the mixing shearing force when added and dispersed in the base resin or the heat during processing.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems of the prior art.
It is easy to handle, there is no trouble due to oil separation during molding, an oil retainer with excellent moldability is used, and oil leaching at the sliding interface is appropriately suppressed, and oil retention is good, Therefore, oil-containing microcapsules capable of sustaining lubricating performance for a long period of time and a method for producing the same, and
It is an object to provide a resin composition containing such oil-containing microcapsules.

[0010]

The present inventors need to impart appropriate mechanical strength to a microcapsule as a liquid lubricant holding body, and this requirement is to provide the microcapsule with, for example, a three-dimensional net structure. It has been found that the formation can be achieved by using the urethane polymer film, and the present invention has been completed.

Thus, according to the present invention, (1) an oil-containing microcapsule obtained by coating a liquid lubricating oil with a three-dimensional urethane polymer film, (2) an aromatic polyvalent isocyanate represented by the structural formula 1 and a fat A hydrophobic liquid containing a genus-type polyvalent isocyanate and a liquid lubricating oil is prepared, the hydrophobic liquid is emulsified and dispersed in a hydrophilic liquid, and a polyhydric alcohol and a cross-linking agent are added to the hydrophilic liquid. The microcapsule according to the above (1), which includes the steps of coating the droplets of the lubricating oil with a three-dimensional urethane polymer film formed by simultaneously advancing a polymerization reaction and a crosslinking reaction on the surface of a droplet of the ionic liquid. Manufacturing method of

And (3) A microcapsule-containing resin composition obtained by mixing the oil-containing microcapsules according to (1) above with a polyurethane elastomer.

The oil-containing microcapsules described in (1) above have a certain mechanical strength because the wall film is made of urethane polymer having a three-dimensional network structure, and this is dispersed in the base resin. It is not destroyed by the mixing shearing force at the time of heating or the heat at the time of processing. Therefore, the resin composition containing the microcapsules can be molded without trouble due to oil separation.

The production method described in (2) above is characterized in that a crosslinking agent and a polyhydric alcohol are used in combination in order to produce a polymer film having a three-dimensional network structure by intermolecular crosslinking. The mechanical strength of the produced polymer film is determined from both aspects of the film thickness and the crosslinking density, the film thickness is determined mainly by the weight ratio of isocyanate to the lubricating oil, and the crosslinking density is determined mainly by the amounts of the crosslinking agent and the polyhydric alcohol. Therefore, by adjusting the reaction liquid components, a urethane polymer film having appropriate mechanical strength is produced.

In carrying out the production method of the present invention, an aromatic polyvalent isocyanate and an aliphatic polyvalent isocyanate are dissolved in a liquid lubricating oil to prepare a hydrophobic liquid, which is poured into a hydrophilic liquid mainly composed of water. Add and stir at high speed to emulsify and disperse. The polyhydric alcohol is added to the hydrophilic liquid and the temperature is raised, the crosslinking agent is dissolved therein, and the polymerization reaction and the crosslinking reaction are simultaneously advanced on the surface of the droplets of the hydrophobic liquid. In this way, a polymer film having a three-dimensional network structure is formed on the surface of the droplets, coated with liquid lubricating oil to form oil-containing microcapsules, which are separated and dried to obtain powdery microcapsules with good fluidity.
The microcapsules thus obtained are not destroyed by the mixing shearing force when added to and dispersed in the base resin or heat during processing, and are broken by the pressure and friction on the sliding surface to leach the lubricating oil. .

As the aromatic polyvalent isocyanate in the above production method, triphenyl dimethylene triisocyanate, tetraphenyl trimethylene tetraisocyanate, pentaphenylene tetramethylene pentaisocyanate, etc., or their inclusions may be used. Examples of the valent isocyanate include trimethylene diisocyanate, hexamethylene diisocyanate, propylene-
Examples of the polyhydric alcohol include 1,2-diisocyanate, butylene-1,2-diisocyanate, and ethylidyne diisocyanate. Trihydric polyols such as glycerin, trimethylolpropane, hexanetriol, and triethanolamine, diglycerin, and pentaerythritol. , Tetrafunctional polyols such as ethylenediamine, methyl glucogit and aromatic diamine, and hexafunctional polyols such as sorbitol, and methylene-bis-ortho-chloroaniline (MOCA), a melendianiline / NaCl complex as a cross-linking agent, 1,2-bis (2-aminophenyl-thio) ethane, trimethylene glycol-
P-aminobenzoate etc. are illustrated.

In the resin composition described in (3) above, a polyurethane elastomer is used as a base resin, and oil-containing microcapsules having a urethane polymer film are mixed and dispersed in the base resin. Since the affinity for the microcapsules is good and the powdery microcapsules have good fluidity, a uniform dispersed state can be obtained. Further, the microcapsules are not destroyed by the mixing shearing force when the microcapsules are added and dispersed in the base resin or the heat during processing, and therefore the resin composition can be molded without stickiness or trouble due to oil separation. The resin composition molded product thus obtained exhibits excellent mechanical properties and can be suitably used as a friction and wear resistant material for high loads.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION As a preferred embodiment of the production method (2) according to the present invention, (4) the weight ratio of the lubricating oil to the mixture of the aliphatic polyvalent isocyanate and the aromatic polyvalent isocyanate is preferable. Is 4/4 or more and 15/4 or less, more preferably 5/4 or more and 10/4 or less, and the weight ratio of the aromatic polyvalent isocyanate to the aliphatic polyvalent isocyanate in the isocyanate mixture is preferably 1 /.
7 to 15/1, more preferably 3/5 to 3 /
1 or less, the weight ratio of the polyhydric alcohol to the isocyanate mixture is preferably 1/16 or more and 12/16 or less, more preferably 4/16 or more and 8/16 or less, and the weight ratio of the crosslinking agent to the isocyanate mixture is preferably 0. The production method according to (2) above, which is in the range of 0.01 / 8 or more and 0.2 / 8 or less, and more preferably 0.05 / 8 or more and 0.1 / 8 or less.

In embodiment (4), the weight ratio of lubricating oil to the above isocyanate mixture (lubricating oil / mixture)
When it is less than 4/4, the thickness of the polymer film becomes excessive, and when it exceeds 15/4, the thickness is insufficient, which is not preferable. If the weight ratio of the aromatic polyvalent isocyanate to the aliphatic polyvalent isocyanate is less than 1/7, a thread-like polymer is likely to be formed, and if it exceeds 15/1, the polymerization rate decreases, which is not preferable. Further, when the weight ratio of the polyhydric alcohol to the mixture is less than 1/16, the functional group of the isocyanate remains, and when it exceeds 12/16, the alcohol remains, which is not preferable. Further, when the weight ratio of the cross-linking agent to the mixture is less than 0.01 / 8, the cross-linking density is lowered and the mechanical strength of the polymer film is insufficient, and 0.2 /
If it exceeds 8, the crosslink density becomes too high and the polymer film becomes too hard, which is not preferable. Therefore, it is necessary to adjust the amount of each component of the reaction solution within the numerical range described, but there is a more preferable range in the middle.

As a preferred embodiment of the resin composition (3) according to the present invention, (5) the polyurethane elastomer is formed into a target molded article by a casting polymerization reaction of a polyurethane prepolymer containing the oil-containing microcapsules. The microcapsule-containing resin composition described in (3) above, which is produced at the same time, can be mentioned.

A general form of the resin composition (3) is obtained by dispersing oil-containing microcapsules in a preliminarily ground polyurethane elastomer and pelletizing the microcapsules by an extruder. In this case, the desired sliding member is formed by injection molding. On the other hand, the embodiment (5) is a so-called casting resin. In this case, the object is molded by adding a chain extender and polymerizing in a mold.

[0021]

[Examples] In the following, examples of production of oil-containing microcapsules according to the present invention and results of abrasion tests of sliding members containing the microcapsules are shown, and the effects of the present invention are verified in comparison with Comparative Examples. .

Example 1 100 parts of mineral oil (200 #) and 100 parts of aromatic polyisocyanate [Nippon Polyurethane Co., Ltd.]
MR-100] 40 parts and 40 parts of hexamethylene diisocyanate, which is an aliphatic polyvalent isocyanate, are dissolved to form a hydrophobic liquid, and 9 parts of polyvinyl alcohol are mixed with 9 parts of water.
It was added to the hydrophilic liquid dissolved in 00 parts and stirred at 600 rpm to emulsify. While stirring, add 35 parts of trimethylolpropane, which is a polyhydric alcohol, to the hydrophilic liquid and add 6
The temperature is raised to 0 ° C., 10 parts of the cross-linking agent MOCA is added, and the reaction is performed for 60 minutes. Since the reaction solution is separated into two layers, the upper layer microcapsules are washed with water using a centrifuge, filtered and dried.
0 g of powdery oil-containing microcapsules were obtained.

Polyester type polyurethane prepolymer
[Nippon Polyurethane Co., Ltd. Coronate C-404
7] was heated to 80 ° C., the oil-containing microcapsules obtained above were added, and after defoaming, 4 parts of 1,4 butanediol was added and mixed with stirring, and after 20 minutes, gold heated to 120 ° C. was added. It was cast in a mold and left for 20 minutes. Place the upper mold at 120 ° C, 4
Primary vulcanization was performed for 0 minutes, and secondary vulcanization was further performed at 120 ° C. for 10 hours to obtain a molded product having a microcapsule content of 0, 5 or 10% by weight.

The results of the abrasion test and the mechanical characteristics are shown in Table 1, and the change with time of the friction coefficient was as shown in FIG. For example, in the case of adding 10% by weight of oil-containing microcapsules, the friction coefficient μ was stable at about 0.21 and the wear amount was almost zero. In addition, the hardness (JIS-A) from the microcapsule content of 0,
The deterioration of mechanical properties such as 100% tensile stress (kgf / cm2), elongation (%), and tensile strength (kgf / cm2) was small, and it was within the practical range.

[Table 1]

Example 2 Aromatic polyisocyanate was added to 100 parts of mineral oil (200 #) [Nippon Polyurethane Co., Ltd.].
MR-400] (40 parts) and 40 parts of hexamethylene diisocyanate, which is an aliphatic polyvalent isocyanate, are dissolved in a hydrophobic liquid, and 9 parts of polyvinyl alcohol are mixed with 9 parts of water.
It was added to the hydrophilic liquid dissolved in 00 parts and stirred at 600 rpm to emulsify. While stirring, 35 parts of pentaerythritol, which is a polyhydric alcohol, was added to the hydrophilic liquid to obtain 60.
The temperature is raised to 0 ° C., 10 parts of the crosslinking agent MOCA is added, and the reaction is performed for 60 minutes. Since the reaction solution is separated into two layers, the upper layer microcapsules are washed with water using a centrifuge, filtered and dried.
Thus, g of powdery oil-containing microcapsules were obtained.

After degassing by heating 100 parts of the polymer polyol to 110 ° C., 3 parts of the mold release agent and diisocyanate MDI12
6 parts and 45 parts of the chain extender 1,4 butanediol are mixed and reacted, poured into a mold at 110 to 120 ° C, and 90 ° C.
After aging for 20 hours, it was pulverized. The oil-containing microcapsules obtained above are blended to produce pellets with an extruder, and the product is molded with an injection molding machine.
Alternatively, a molded product containing 10% by weight was obtained.

The results of the abrasion test and the mechanical characteristics are shown in Table 1, and the change with time of the friction coefficient was as shown in FIG. For example, in the case of adding 10% by weight of oil-containing microcapsules, the friction coefficient μ was stable at about 0.32, and the wear amount was almost zero. In addition, the deterioration of mechanical properties from the microcapsule content of 0 was small, and it was within the range of practicality.

(Comparative Example) As a comparative example to be compared with the above Examples 1 and 2, 0 or 5 wt% P as a solid lubricant was used.
A friction and wear resistant material in which TFE was added to a thermoplastic elastomer was taken, and its friction coefficient and wear amount were measured. The results of the abrasion test and the mechanical properties are shown in Table 1, and the change with time of the friction coefficient was as shown in FIG.

The wear test of the molded product was carried out using a friction wear tester shown in FIG. In FIG. 4, reference numeral 1 is a test piece to be subjected to a wear test, 2 is a cylindrical mating member, and 3 is a friction surface. The mating material 2 is placed on the test piece 1, and the mating material 2 is rotated around the central axis while applying a load load downward. In the wear test of the molded products in the above-mentioned Examples and Comparative Examples, the material of the mating material was S45C, and the load was 5 kgf / cm.
2. The linear velocity was 1 m / min, the lubrication state was dry, and friction rotation was continuously performed for 20 hours, and the friction coefficient μ and the wear amount (μm) were measured.

[0030]

The oil-containing microcapsules according to the present invention are
It is not destroyed by the mixing shearing force when it is added to and dispersed in the base resin and the heat during processing, and therefore the resin composition containing the microcapsules can be molded without trouble due to oil separation.

The method for producing oil-containing microcapsules according to the present invention is characterized in that a cross-linking agent and a polyhydric alcohol are used in combination in order to produce a polymer film having a three-dimensional network structure by intermolecular cross-linking. The mechanical strength of the produced polymer film is determined from both aspects of film thickness and crosslink density. The film thickness is controlled mainly by the weight ratio of isocyanate to lubricating oil, and the crosslink density is controlled mainly by the amount of crosslinker and polyhydric alcohol. By doing so, a urethane polymer film having appropriate mechanical strength is produced.

In the resin composition containing oil-containing microcapsules according to the present invention, the affinity between the base resin and the microcapsules is good, and a uniform dispersed state is obtained. Further, when the microcapsules are added and dispersed, mixing shearing force and processing Not destroyed by the heat of. Therefore, the present resin composition can be molded without stickiness or trouble due to oil separation, and the obtained molded product exhibits excellent mechanical properties and can be suitably used as a friction and wear resistant material for high loads.

[0033]

[Brief description of drawings]

FIG. 1 is a graph showing a change over time in a friction coefficient of a molded article as Example 1.

FIG. 2 is a graph showing a change with time of a friction coefficient in a molded article as Example 2.

FIG. 3 is a graph showing the change over time in the coefficient of friction of a molded product as a comparative example.

FIG. 4 is an explanatory diagram of a friction wear tester.

[Explanation of symbols]

 1 ... test piece 2 ... mating material 3 ... friction surface

Claims (5)

[Claims] 1. An oil-containing microcapsule obtained by coating a liquid lubricating oil with a three-dimensional urethane polymer film. 2. A hydrophobic liquid containing an aromatic polyvalent isocyanate represented by the structural formula 1 and an aliphatic polyvalent isocyanate and a liquid lubricating oil is prepared, and the hydrophobic liquid is emulsified and dispersed in a hydrophilic liquid. By adding a polyhydric alcohol and a cross-linking agent to the hydrophilic liquid, a three-dimensional urethane polymer film produced by simultaneously advancing the polymerization reaction and the cross-linking reaction on the droplet surface of the hydrophobic liquid Each step of coating the lubricating oil droplets,
The method for producing the microcapsule according to claim 1. Embedded image 3. A resin composition containing microcapsules obtained by mixing the oil-containing microcapsules according to claim 1 with a polyurethane elastomer. 4. The weight ratio of the lubricating oil to the mixture of the aliphatic polyvalent isocyanate and the aromatic polyvalent isocyanate is preferably 4/4 or more and 15/4 or less, more preferably 5/4 or more and 10/4 or less. The weight ratio of the aromatic polyvalent isocyanate to the aliphatic polyvalent isocyanate in the isocyanate mixture is preferably 1/7 or more and 15/1 or less, more preferably 3
/ 5 or more and 3/1 or less, the weight ratio of the polyhydric alcohol to the isocyanate mixture is preferably 1/16 or more and 12/16 or less, more preferably 4/16 or more and 8/16 or less, and the weight of the cross-linking agent to the isocyanate mixture. The production method according to claim 2, wherein the ratio is preferably 0.01 / 8 or more and 0.2 / 8 or less, more preferably 0.05 / 8 or more and 0.1 / 8 or less. 5. The microcapsule-containing resin composition according to claim 3, wherein the polyurethane elastomer is produced at the same time as the formation of a target molded article by a cast polymerization reaction of a polyurethane prepolymer containing the oil-containing microcapsules.