KR100581664B1 - A poly urethane resin composition for a midsole - Google Patents

Abstract

To provide a polyurethane resin composition capable of providing a shoe midsole having a low density of 0.20-0.30 g / dl and having excellent physical properties, and a polyol mixture comprising a polyol, a curing agent, water and microspherical organic fillers, and an isocyanate reactor end It provides a polyurethane resin composition for shoe midsole comprising a prepolymer comprising a. Wherein the polyol mixture comprises 80-100% by weight polyester polyol and 0-20% by weight polyether polyol, each of which has a functionality of 1.8-5, and the average functionality as a polyol mixture is 2.0-2.5, and the polyol average molecular weight is 500-5000.

Polyurethane, Shoe midsole, Polyester polyol, Polyether polyol, Isocyanate

Description

Polyurethane resin composition for shoe midsole {A POLY URETHANE RESIN COMPOSITION FOR A MIDSOLE}

Industrial use field

The present invention relates to a polyurethane resin composition for shoe midsole, and more particularly, to a polyurethane resin composition capable of lowering the density of shoe midsole to 0.20-0.30 g / cc.

Prior art

Over the past ten years, the design of the shoes has been brilliant and the functionality has been emphasized, and the polyurethane foaming system, which has excellent mechanical strength, formability and high economical efficiency, has been used for the manufacture of soles, especially midsoles. It is applied a lot.

Since the density of the midsole provided by the conventional polyurethane resin composition is about 0.30-0.38g / cc, it is urgent to reduce the density of the midsole in consideration of the recent trend of lightweight shoes.

One way to achieve low density of the midsole is to adjust the amount of water, which is a blowing agent. Increasing the amount of water to increase the amount of foam, there is a problem that the mechanical properties of the midsole is reduced because the shape of the cell becomes irregular while the size of the inner cell (cell) increases. Therefore, while controlling the amount of water, which is a blowing agent, a fundamental structural change of the polymer or a change of raw material is required.

As an attempt to reduce the density of the shoe sole by changing the structure of the polymer, a low specific gravity technique using a polyether polyol has been studied. Polyether type polyol has the advantage of improving the low temperature flexural properties of the shoe midsole, there is a problem such as causing a decrease in the overall physical properties there is a limit to apply to the shoe midsole. Shoe midsoles using polyester type polyols instead of polyether type polyols are known to have excellent tensile strength, elongation at break and wear resistance, but low temperature properties are lower than those of polyether type polyols (J. of Elastomer). and Plastics, Vol. 26, 327).

It is an object of the present invention to provide a polyurethane resin composition which can provide a shoe midsole having a low density of 0.20-0.30 g / dL and a free foam density of 0.10-0.20 g / dL and having excellent physical properties.

In order to achieve the above object of the present invention, the present invention provides a polyol, a polyol mixture comprising water and expandable microspherical organic filler, and a polyurethane resin composition for shoe soles comprising a prepolymer comprising an isocyanate reactor end The polyol mixtures comprise 80-100% by weight of polyester polyols and 0-20% by weight of polyether polyols, each having a functionality of 1.8-5 and an average functionality of 2.0- 2.5 and a polyol average molecular weight of 500-5000 provides a polyurethane resin composition for shoe soles.

Hereinafter, the present invention will be described in more detail.

The present inventor adopts expandable fine spherical organic filler as auxiliary foaming agent to lower the density of shoe midsole to 0.20-0.30g / cc, and improves the polyol component constituting the polymer structure to improve the physical property deterioration due to the low density of shoe midsole Thus, the present invention has been completed.

Polyurethane resin composition for shoe sole according to the present invention is a polyol having a prepolymer (so-called P liquid) containing the end of the isocyanate reactor and an active hydrogen reactor capable of reacting with isocyanate, water as the main foaming agent, expandable foaming agent auxiliary Polyol mixtures (so-called R solutions) including fine spherical organic fillers and the like. The reaction ratio of the prepolymer and the polyol mixture is based on the molar ratio of the isocyanate group (-NCO) included in the prepolymer and the active hydrogen reactor (-OH) included in the polyol mixture, and the preferred molar ratio of -NCO / -OH is In the range of 0.90-1.1. If it is out of this range, sufficient molecular weight is not grown during the reaction, and properties such as elongation and solvent resistance are lowered.

The prepolymer (P liquid) including the end of the isocyanate reactor is prepared by catalytic or noncatalytic reaction of organic isocyanates with a polyol, and the NCO% is preferably 18-24%. Examples of the organic diisocyanates include 4,4′-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, carbodi Mid-modified diisocyanates or mixtures thereof can be used, among which 4,4'-diphenylmethane diisocyanate is used alone or 4,4'-diphenylmethane diisocyanate and carbodiimide-modified diisocyanate are mixed. Use is preferred in view of economics and storage stability. As the polyol, polyester polyol may be used alone, or a mixture of polyester polyol and polyether polyol may be used.

The polyol included in the polyol mixture (Liquid R) is a polyester polyol or a mixture of polyester polyol and polyether polyol having a functionality of 1.8-5.0 and a molecular weight of 500-5000, and the average functionality of the final polyol mixture is It is 2.0-2.5, and it is preferable that the usage-amount is 80-90 weight% of a polyol mixture (R liquid). If the amount of polyol is less than 80%, the ratio of polyol for constituting the polyurethane resin foam may not be sufficient, so the physical properties of the manufactured shoe sole may be deteriorated. If the amount of polyol is more than 90%, it is relatively used as a blowing agent. There is a problem in that the amount of water is reduced and the density of the shoe midsole is increased. The polyester polyol is used in 80-100% by weight of the polyol, the polyether polyol is preferably used in 0-20% by weight of the polyol. If the polyester polyol is used at less than 80% by weight, the cell size of the foam becomes irregular, resulting in a problem of deterioration of the physical properties of the shoe sole. Since the polyether polyol acts to improve the low temperature characteristics of the shoe midsole, when using a mixture of polyester polyol and polyether polyol than when using polyester polyol alone, it is possible to improve low temperature bendability. When the amount of the polyether polyol used exceeds 20% by weight of the total polyol, overall physical properties such as tensile strength of the shoe midsole, elongation at break, abrasion resistance, and the like, may be deteriorated.

Polyester polyols react aliphatic dibasic acids such as adipic acid, azelaic acid, succinic acid and malonic acid with acyclic glycols such as ethylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol and neopentane glycol. Can be obtained. Trimethylolpropane or glycerol may be used instead of acyclic glycol to increase the functionality (f) of the polyester polyol.

Polyether polyol can be obtained through the polymerization of polyhydric alcohol and alkylene oxide. Polyhydric alcohols include ethylene glycol, propylene glycol, trimethylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol 1,2-pentanediol, 1,4-pentanediol, 1,5- Pentanediol, 1,6-hexanediol, glycerol, trimethylolpropane and the like can be used, and ethylene oxide, propylene oxide, butylene oxide and the like can be used as the alkylene oxide. Polyether polyols may also be prepared from tetrahydrofuran in addition to the methods described above. Polyether polyols produced by the above methods include polyoxyethylene glycol, polyoxypropylene glycol, polyoxybutylene glycol, polytetramethylene glycol, and the like.

Water is used as the main foaming agent and also serves to adjust the density of the polyurethane resin composition according to the present invention. The amount of water used depends on the NCO% of the prepolymer. If the NCO% is 22%, it is preferred to use 0.5-2.5% by weight of the polyol mixture. If the amount of water used is less than 0.5% by weight, the density of the shoe sole is increased due to the small amount of foam. If the amount of water exceeds 2.5% by weight, the inner cell constituting the foam is uneven and excessively large. It becomes large and the physical property of the shoe midsole falls.

Expandable microspherical organic fillers are used as auxiliary blowing agents, in which shells of copolymerized polymers of acrylonitrile and vinylidene chloride surround isobutane. The isobutane is present in the liquid phase at room temperature due to the pressure from the shell. When heat is supplied to the microspheres, the polymer shell is softened to vaporize the isobutane. As a result, the volume of the organic fill expands about 60 times compared to before the heat is supplied. At this time, the heat supplied to foam the organic filler is obtained through the foaming reaction of the isocyanate and water, it does not need to be supplied from the outside separately. Thermally expanded organic fills are arranged between the bubbles produced by the reaction of isocyanate and water, thereby reducing the amount of polyurethane resin located between the bubbles. That is, the amount of polyurethane present per unit volume of foam is reduced. On the same principle, the use of expandable microspherical organic fillers as auxiliary blowing agents can achieve a low density of shoe midsoles. The organic filler may be a commercially available product, for example Expancel 093 DU of Akzo noble. The amount of organic filler used is preferably 0.1-5.0% by weight of the polyol mixture. When the amount of use is less than 0.1% by weight, the effect of lowering the density of the shoe midsole is not sufficient, and when the amount of use is more than 5.0% by weight, the effect of lowering the density of the shoe midsole is sufficient, but may lower the physical properties.

The polyol mixture (R liquid) may further include a curing agent. As the curing agent, it is preferable to use diols, which can serve as a chain extender. Such diols include ethylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentane glycol and the like which are acyclic glycols. Preferably ethylene glycol is used. The amount used is preferably 5-12% by weight of the polyol mixture. If the amount is less than 5% by weight, the surface hardness of the shoe midsole is lowered, the wear resistance is lowered, there is a high possibility of problems in the post-process, such as adhesion to the outsole (outsole). If the amount is more than 12% by weight, the hardness of the shoe midsole is too high, causing a disadvantage in that the fit is reduced.

In addition, the polyol mixture (R liquid) may further include a stabilizer for heat resistance and weather resistance, a fungicide for preventing mold development, a foam stabilizer, or a pigment for coloration as other additives. Preferably, the stabilizer is used at about 2% by weight of the polyol mixture, the antimicrobial agent is at about 0.5% by weight of the polymer mixture, and the foam stabilizer is used at about 0.2-1.0% by weight of the polymer mixture. Here, the foam stabilizer is an additive that serves to control the size and shape of the bubbles generated during the reaction by mixing the polyurethane resin composition, the size of the bubble is not uniform when not used to reduce the physical properties of the shoe midsole There is concern.

The following presents a preferred embodiment to aid the understanding of the present invention. However, the following examples are merely provided to more easily understand the present invention, and the present invention is not limited to the following examples.

Example 1-5 and Comparative Example 1

Preparation of Prepolymer (P Liquid) Containing Isocyanate Reactor End

65 wt% of 4,4′-diphenylmethane diisocyanate and 5 wt% of carbodiimide-modified 4,4′-diphenylmethane diisocyanate were first added to a 20-l reactor, followed by stirring with a polyester polyol (OHV = 58, f = 2.1) 30% by weight was added. Stirring was continued while maintaining the reaction temperature at 80 ° C. After reacting for about 90 minutes, NCO% was measured by sampling, and the NCO% was corrected to 22% and discharged. The discharged P liquid was placed in a P stock liquid tank of the foaming machine and maintained at about 40 ± 3 ° C.

Preparation of Polyol Mixture (Liquid R) Having an Active Hydrogen Reactor

Each raw material of Table 1 was placed in a 20 L reactor and sufficiently mixed using a hand mixer, and then placed in an R stock tank of the foaming machine and maintained at about 40 ± 3 ° C.

Raw material Comparative Example 1 Example 1 Example 2 Example 3 Example 4 Example 5 Polyol-a 83.6 82.65 82.65 87.75 86 85 Polyol-b 4.4 4.35 4.35 0 0 0 Ethylene glycol 9.0 9.0 9.0 9.0 9.0 9.0 water 1.0 1.0 1.0 1.0 1.0 1.0 Organic fillers 0 1.0 1.0 0.25 2 3 stabilizator 1.12 1.12 1.12 1.12 1.12 1.12 Antiseptic 0.17 0.17 0.17 0.17 0.17 0.17 Foam stabilizer 0.6 0.6 0.6 0.6 0.6 0.6

* Polyol-a: polyester polyol (f = 2.1, -OH value = 56)

* Polyol-b: polyether polyol (f = 2.0, -OH value = 56)

Organic filler: Expancel 093 DU (Akzo nobel)

* Unit: weight%

 The prepared P liquid and R liquid were mixed in a foaming machine, and foamed under the following foaming conditions, and then the physical properties of the specimens were measured and shown in Table 2.

Foaming Machine Manufacturer: Koryo Automation

Stock solution temperature: 40 ± 3 ℃

Stock tank capacity and configuration: P stock tank 40ℓ, R stock tank 40ℓ,

                       Stir at 70 rpm constant speed

Stock solution usage: P stock solution 20ℓ, R stock solution 20ℓ

Mixing impeller speed: 6,000 rpm

Specimen mold for measuring physical properties: 10cm × 20cm × 1cm

Specimen Mold Temperature: 55 ± 3 ℃

Specimen Operation -NCO / -OH Ratio: 0.97

Specimen work: foamed by adjusting the overexposure amount (barrier) to discharge 1.0 (g) uniformly

Specimen demoulding time: 3 minutes

Properties Comparative Example 1 Example 1 Example 2 Example 3 Example 4 Example 5 Molding specific gravity 0.32 0.257 0.261 0.297 0.235 0.208 Shore A 63 59 58 61 55 51 Tensile strength (kg / ㎡) 33.7 29.2 28.6 32.2 27.4 25.1 % Elongation 442 385 398 426 366 349 Split tear (kgf) 2.78 2.60 2.59 2.71 2.54 2.44

As shown in Table 2, the specimen of Comparative Example 1, which does not use the expandable microspherical organic filler, has a specific gravity of 0.32, but the specimen of Example 1-5 has a low specific density of 0.20-0.30, and the hardness, It can be seen that the physical properties such as tensile strength, elongation and tear resistance are excellent.

The polyurethane resin composition according to the present invention can provide a shoe midsole with excellent physical properties while reducing the density of the shoe midsole to 0.20-0.30 g / cc.

Claims (5)

(A) iv) 80-100% by weight of polyester polyols and 0-20 of polyether polyols         Weight percent, functionality of 1.8-5.0,         With an average molecular weight of 500-5000         80-90 parts by weight of polyol,     Ii) 0.5-2.5 parts by weight of water, and     Iii) 0.1-5.0 parts by weight of expandable microspheres organic filler     A polyol mixture comprising; and a polyol mixture having an average functionality of 2.0-2.5; And (B) a prepolymer having an isocyanate reactor end, Polyurethane resin composition for footwear midsole is 1: 0.9-1.1 molar ratio of the active hydrogen reactor (-OH) and (B) isocyanate group (-NCO) contained in the (A) polyol mixture. delete The polyurethane resin composition for shoe soles according to claim 1, wherein when the polyurethane resin composition for shoe midsole is foamed, a polyurethane foam having a density of 0.20-0.30 g / cc is obtained. 2. The polyurethane resin composition for shoe soles according to claim 1, wherein the expandable fine spherical organic filler is in the form of a shell made of a copolymer of acrylonitrile and vinylidene chloride surrounding isobutane. The method of claim 1, wherein the polyester polyol is aliphatic dibasic acid selected from the group consisting of adipic acid, azelaic acid, succinic acid and malonic acid and ethylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol And a non-cyclic glycol selected from the group consisting of neopentane glycol, wherein the polyether polyol is ethylene glycol, propylene glycol, trimethylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4 Butanediol 1,2-pentanediol, 1,4-pentanediol, 1,5-pentanediol, 1,6-hexanediol, glycerol and trimethylolpropane polyhydric alcohols selected from the group consisting of ethylene oxide, propylene oxide and A polyurethane resin composition for shoe soles, which is obtained by a polymerization reaction of an alkylene oxide selected from the group consisting of butylene oxide.