CN115850631A

CN115850631A - Polyurethane foam and shoe sole

Info

Publication number: CN115850631A
Application number: CN202211142479.3A
Authority: CN
Inventors: 大村京平
Original assignee: Achilles Corp
Current assignee: Achilles Corp
Priority date: 2021-09-24
Filing date: 2022-09-20
Publication date: 2023-03-28

Abstract

Provided are a polyurethane foam which has good rebound resilience, moderately low hardness and excellent permanent compression set, and a shoe sole using the polyurethane foam. The polyurethane foam is constructed in the following manner: the polyurethane foam is characterized by comprising a polyol component and a polyisocyanate component, wherein the polyol component comprises one or more polypropylene glycol-based materials, and the polypropylene glycol-based material having a weight average molecular weight of 4000 or less alone is contained in an amount of less than 50% by mass (including 0) out of the total 100% by mass of the one or more polypropylene glycol-based materials, the weight average molecular weight of the whole of the one or more polypropylene glycol-based materials is 4000 or more and 9000 or less, the average functional group number of the whole is 2.50 or more and 4.00 or less, and the average equivalent weight of the whole is 1600 or more and 2500 or less, and the polyurethane foam is used as a sole member to constitute a shoe sole.

Description

Polyurethane foam and shoe sole

Technical Field

The present invention relates to polyurethane foam and shoe soles.

Background

Heretofore, foams such as polyurethane foams and ethylene-vinyl acetate copolymer foams have been used as structural members for various applications. For example, a sole member manufactured using a polyurethane foam has excellent rebound resilience, and a shoe used in general is not necessarily used, but is also used as a component member of a sole of an athletic shoe such as a walking shoe, a running shoe, or a hiking shoe. The polyurethane foam is not limited to the use as a sole member, and may be used as a mat member such as a mat for laying a floor in a work place or a mat for a mat when a precision machine is installed.

The sports shoe using the sole excellent in rebound elasticity is supported by the foot-back and is easy to take a step, and therefore, an effect of reducing the accumulation of fatigue can be expected during running and walking for a long time. The sole having excellent resilient elasticity is not limited to sports shoes, and can provide effects such as easy walking and less fatigue in general-use shoes used in daily life including business shoes.

In the present invention, the sole means a sole portion of a shoe, and the sole member means a constituent member (material) constituting a part or the whole of the sole.

For example, patent document 1 discloses an invention that is problematic in providing a polyurethane integral skin foam that has a high modulus of elasticity in rebound in a wide temperature range and is excellent in mechanical strength and productivity. Specifically, patent document 1 discloses an invention of a polyurethane integral skin foam which is produced from an organic isocyanate composition (a), a polyol component (B), a catalyst (C) and a blowing agent (D), wherein the organic isocyanate composition (a) is a urethane-modified product of diphenylmethane diisocyanate and polytetramethylene ether glycol having a number average molecular weight of 1000 to 3500, and is an organic isocyanate (a 1) having an isocyanate group content of 7 to 25 mass%.

Patent document 2 discloses a polyurethane foam which has a problem of providing a polyurethane foam having durability and further having resilience and the like. Specifically, patent document 2 discloses a polyurethane foam formed from a polyurethane raw material containing a polyol component, an isocyanate component, a blowing agent, a catalyst, and a foam stabilizer, wherein the polyol component is a polytetramethylene ether glycol having a number average molecular weight of 300 to 3000, an average number of functional groups of 2 to 3, and an average hydroxyl value of 50 to 200mgKOH/g, the isocyanate component contains a predetermined isocyanate group-terminated prepolymer and a predetermined modified MDI, and the content ratio of the prepolymer to the modified MDI, the isocyanate index, and the compression set are specified within predetermined ranges.

In addition, patent document 3 discloses a method for producing a flexible polyurethane foam by reacting a polyether polyol having a high ethylene oxide content with an MDI-based isocyanate in a mold. Patent document 3 describes the following: according to this production method, a polyurethane foam which is easy to release from a mold during mold molding and has excellent compression set and the like can be produced, and the produced polyurethane foam is used for producing, for example, furniture parts made of polyurethane and automobile parts such as automobile seats.

Documents of the prior art

Patent literature

Patent document 1: japanese patent laid-open publication No. 2016-204635

Patent document 2: japanese patent laid-open publication No. 2017-105913

Patent document 3: japanese patent application laid-open No. 2003-523425

Disclosure of Invention

Problems to be solved by the invention

In the technical field related to the use of shoe soles, shoe pads, and the like for repeatedly receiving the weight of a user, urethane foams having an appropriately low hardness are preferable for the reasons of excellent cushioning properties, good feel of the sole when the user applies weight, and the like. Therefore, the polyurethane foam used for these uses is preferably excellent in rebound resilience and moderately low in hardness.

However, when the rebound resilience of the polyurethane foam is increased, the hardness of the polyurethane foam also tends to be increased in general. In addition, urethane foams used for applications to which a load is repeatedly applied, such as shoe sole members and shoe pads, tend to have a shorter product life than those used for furniture and the like. In particular, polyurethane foams having high rebound resilience or low hardness have a problem that the compression set tends to be large.

Accordingly, it is desired to provide a polyurethane foam which has good rebound resilience, moderately low hardness, and small compression set. From the viewpoint of satisfying this expectation, the patent documents 1 to 3 have room for improvement.

The present invention has been made in view of the above problems. That is, the present invention has an object to provide a polyurethane foam which has good rebound resilience, moderately low hardness, and excellent permanent compression set, and a shoe sole using the polyurethane foam.

Means for solving the problems

The polyurethane foam of the present invention is characterized by comprising a polyol component and a polyisocyanate component, wherein the polyol component comprises one or more polypropylene glycol-based materials, and the one or more polypropylene glycol-based materials comprise, in the total 100 mass% of the one or more polypropylene glycol-based materials, a polypropylene glycol-based material having a weight average molecular weight of 4000 or less alone in a range of less than 50 mass% (including 0), wherein the one or more polypropylene glycol-based materials have a weight average molecular weight of 4000 or more and 9000 or less as a whole, have an average functional group number of 2.50 or more and 4.00 or less as a whole, and have an average equivalent weight of 1600 or more and 2500 or less as a whole.

The sole of the present invention is characterized by being constructed by using the polyurethane foam of the present invention as a sole member.

Effects of the invention

According to the present invention having the above-described configuration, it is possible to provide a polyurethane foam which exhibits a suitably low hardness while maintaining good rebound resilience and is excellent in compression set.

The polyurethane foam of the present invention has the above excellent physical properties, and can be used in various technical fields. For example, a shoe sole provided with a sole member formed using the polyurethane foam of the present invention is preferably used as a sole of a sport shoe or a daily use shoe.

Detailed Description

[ polyurethane foam ]

The polyurethane foam of the present invention is produced using a polyol component, a blowing agent, a catalyst, a foam stabilizer, an isocyanate component, and the like. Accordingly, the polyurethane foam of the present invention comprises all or a portion of the polyol component, the isocyanate component, and other components.

The polyol component contained in the polyurethane foam of the present invention contains one or more polypropylene glycol types. In the present invention, the polypropylene glycol system having a weight average molecular weight of 4000 or less alone is contained in a range of less than 50 mass% (including 0) in a total of 100 mass% of the above one or more polypropylene glycol systems.

The one or more polypropylene glycol-based polymers have a weight average molecular weight of 4000 to 8200 inclusive, an average functional group number of 2.50 to 4.00 inclusive, and an average equivalent weight of 1600 to 2500 inclusive.

Hereinafter, in the present invention, one or more polypropylene glycol systems contained in the polyol component constituting the polyurethane foam of the present invention may be referred to as "polypropylene glycol system group". That is, in the polyurethane foam of the present invention, when two or more polypropylene glycol types are contained, they are collectively referred to as "polypropylene glycol type group", and even when one polypropylene glycol type is contained as a polyol component, the one polypropylene glycol type may be referred to as a polypropylene glycol type group for convenience.

The individual weight average molecular weight means the weight average molecular weight of each of the polypropylene glycol groups contained in the group of polypropylene glycol groups. The above-mentioned overall weight average molecular weight means the weight average molecular weight of the polypropylene glycol group calculated using the individual weight average molecular weight and mass ratio of each polypropylene glycol contained in 100 mass% of the polypropylene glycol group.

By satisfying the above constitution, the present invention can provide a polyurethane foam which has both high rebound resilience and low hardness and is excellent in compression set. The polyurethane foam of the present invention has good moldability because it has a small shrinkage rate after molding or does not substantially shrink. The following will explain the details of the polyurethane foam of the present invention. In the following description, preferred numerical ranges of the present invention are sometimes appropriately shown. In this case, the preferable range, more preferable range, and particularly preferable range in relation to the upper limit and the lower limit of the numerical range may be determined by all combinations of the upper limit and the lower limit.

[ polyol component ]

The polyol component comprises a polyol. The polyol component in the present invention includes polypropylene glycol.

A polypropylene glycol system:

the polypropylene glycol contained in the polyol component may be one kind, or two or more kinds. The polypropylene glycol can be used in all polypropylene glycol systems that can be used in the production of polyurethane foams, within the range that does not impair the intended effects of the present invention.

More specifically, the polypropylene glycol may be any polypropylene glycol containing an oxypropylene skeleton, and may be, for example, a homopolymer of polypropylene glycol or a copolymer of oxypropylene and other components, and among these, a glycol (polyoxyethylene polyoxypropylene glycol) which is a copolymer of oxyethylene and oxypropylene is preferred.

The two or more polypropylene glycol types contained in the polyol component are either of a type of two or more polypropylene glycol types containing different compound names, or a type of two or more polypropylene glycol types containing the same compound name and having any one or all of a weight average molecular weight, a functional group number, and an equivalent weight different from each other. For example, as an example of the latter, a mode in which two or more polyoxyethylene polyoxypropylene glycols having different weight average molecular weights are contained as the polyol component in the polyurethane foam can be cited.

Polypropylene glycol is a polyol which is amorphous and can realize a low hardness without impairing good rebound elasticity. From this viewpoint, in the present invention, it is preferable that at least one kind of polypropylene glycol (polypropylene glycol group) is contained in an amount of 90% by mass or more, more preferably 95% by mass or more, and particularly preferably substantially 100% by mass, based on 100% by mass of the polyol component. The polypropylene glycol-based group and the other polyols may be contained in an amount of less than 100% by mass based on 100% by mass of the polyol component without departing from the gist of the present invention.

(weight average molecular weight)

The weight average molecular weight of the polypropylene glycol is not particularly limited, but is preferably 3000 to 10000, more preferably 4000 to 10000, still more preferably 4500 to 10000, and particularly preferably 6500 to 9000. By making the weight average molecular weight of the polypropylene glycol based material alone 3000 or more, the effect of reducing the hardness of the polyurethane foam becomes high, and this tendency becomes more remarkable as the weight average molecular weight becomes larger. Further, by setting the weight average molecular weight to 10000 or less, the reactivity of the polyol with isocyanate at the time of urethane reaction can be maintained well, and the moldability of the polyurethane foam is good.

On the other hand, in the present invention, the weight average molecular weight of the whole polypropylene glycol group is adjusted to 4000 to 9000. When the polypropylene glycol is one type contained in the polypropylene glycol group, the total weight average molecular weight corresponds to the individual weight average molecular weight of the polypropylene glycol. When two or more polypropylene glycols are contained in the polypropylene glycol group, the total weight average molecular weight is calculated from the individual weight average molecular weights and the blending ratios of the two or more polypropylene glycols.

If the total weight average molecular weight is less than 4000, shrinkage during molding of the polyurethane foam occurs, curing is not good, and it is difficult to exhibit good elastic modulus of resilience and compression set. When the total weight average molecular weight exceeds 9000, the viscosity of the polyurethane foam to be molded becomes too high, and the moldability may become poor. From the above viewpoint, the weight average molecular weight of the whole group of polypropylene glycol-based polymers is preferably 4500 or more and 8700 or less, more preferably 5000 or more and 8500 or less, and still more preferably 5500 or more and 8200 or less.

In the present invention, as described above, polypropylene glycol systems exhibiting various weight average molecular weights can be used, but it is important that the polypropylene glycol system alone having a weight average molecular weight of 4000 or less is contained in a range of less than 50% by mass (including 0) in 100% by mass of the group of polypropylene glycol systems. For example, even if the weight average molecular weight of a polypropylene glycol group including two or more polypropylene glycols is within the above-described preferred range, when 50 mass% or more of the polypropylene glycols alone having a weight average molecular weight of 4000 or less are included in 100 mass% of the polypropylene glycol group, shrinkage of the polyurethane foam during production is significant, and there is a concern that a polyurethane foam that can be sufficiently used as a product cannot be produced.

(average number of functional groups)

The average number of functional groups of the polypropylene glycol used as the polyol of the present invention is not particularly limited, but is preferably 2 or more and 4 or less. By setting the average number of functional groups of the polypropylene glycol based resin to 2 or more and 4 or less, good reactivity is achieved, and the polyurethane foam can be easily molded.

The individual average functional group number means the average functional group number of each of the polypropylene glycol groups included in the polypropylene glycol group.

In the present invention, the average number of functional groups of the polypropylene glycol group as a whole is adjusted to 2.50 or more and 4.00 or less. When the polypropylene glycol contained in the polypropylene glycol group is one type, the average number of functional groups in the whole is equivalent to the average number of functional groups of the polypropylene glycol alone, and when the number is two or more, the average number of functional groups in the whole is calculated from the average number of functional groups of the two or more polypropylene glycol systems alone and the blending ratio.

If the average number of functional groups in the whole is less than 2.50, shrinkage of the polyurethane foam during production may be significant. When the average number of functional groups of the whole exceeds 4.00, there is a problem that the number of crosslinking points increases and the foam becomes hard. From the above viewpoint, the average number of functional groups of the polypropylene glycol group as a whole is preferably 2.60 or more and 4.00 or less, more preferably 2.70 or more and 4.00 or less, and still more preferably 2.90 or more and 4.00 or less.

(average equivalent weight)

The average equivalent weight of the polypropylene glycol used as the polyol of the present invention is not particularly limited, but is preferably 1600 to 2500 inclusive. When the individual average equivalent weight of the polypropylene glycol is within the above preferred range, the average equivalent weight of the whole, which will be described later, can be easily adjusted to a favorable numerical range.

The individual average equivalent weight means the average equivalent weight of each of the polypropylene glycol-based materials contained in the group of polypropylene glycol-based materials. In addition, in connection with the present invention, the equivalent weight means a value obtained by dividing the weight average molecular weight of the PPG by the average number of functional groups alone.

In the present invention, the average equivalent weight of the whole group of polypropylene glycol-based polyols contained in the polyol is adjusted to 1600 to 2500 inclusive. In the case where the polypropylene glycol contained in the polypropylene glycol group is one kind, the average equivalent weight of the whole is equivalent to the average equivalent weight of the polypropylene glycol alone, and in the case where the polypropylene glycol group is two or more kinds, the average equivalent weight of the whole is calculated from the average equivalent weight of the two or more kinds of polypropylene glycol alone and the blending ratio.

If the average equivalent weight of the whole is less than 1600, shrinkage during molding of the polyurethane foam occurs, curing is poor, or it is difficult to exhibit good elastic modulus of resilience and compression set. When the average equivalent weight of the whole exceeds 2500, the viscosity of the polyurethane foam to be molded becomes too high, and the moldability becomes poor, or it becomes difficult to exhibit a good modulus of elasticity for resilience. From the above viewpoint, the average equivalent weight of the whole polypropylene glycol group contained in the polyol is preferably 1600 to 2400, more preferably 1700 to 2400, and still more preferably 1800 to 2400.

[ isocyanate component ]

The polyurethane foam of the present invention comprises an isocyanate component. The isocyanate component contains isocyanate.

As the isocyanate contained in the isocyanate component, conventionally known isocyanates used in the production of polyurethane foams can be appropriately selected and used. One kind of the isocyanate may be used, or two or more kinds may be used in combination. Further, one or more isocyanates may be used in combination with the isocyanate group-terminated prepolymer described later, or only the isocyanate group-terminated prepolymer may be used as the isocyanate.

Modified MDI:

more specifically, the isocyanate contained in the isocyanate component preferably contains modified MDI (modified diphenylmethane diisocyanate).

Specific examples of the modified MDI which is liquid at ordinary temperature include a polymer (crude MDI), a urethane-modified product, a urea-modified product, an allophanate-modified product, a biuret-modified product, a carbodiimide-modified product, a uretonimine-modified product, a uretdione-modified product, and an isocyanurate-modified product. Among them, from the viewpoint of excellent molecular (crosslinked) structure after reaction with the polyol component, it is preferable to select a polymer (crude MDI) and/or a carbodiimide-modified product as the modified MDI. The polymer (crude MDI) may be, for example, polymethylene polyphenylisocyanate, a polyisocyanate mixture of diphenylmethane diisocyanate (MDI) and polyphenylmethane polyisocyanate (polymeric MDI), or the like.

Isocyanate-terminated prepolymer:

the isocyanate group-terminated prepolymer (hereinafter, also simply referred to as prepolymer) contained in the isocyanate component is obtained by reacting an isocyanate component with a polyol component having a weight average molecular weight of 3000 to 9000, and preferably contains an isocyanate group-terminated prepolymer having an isocyanate group content of 3 to 15 mass%.

Examples of the polyol component used in the isocyanate group-terminated prepolymer include polyether polyol, polyester polyol, and polymer polyol. Among them, polyether polyols are preferably used. As the polyether polyol, the above-mentioned polypropylene glycol type, polytetramethylene ether glycol, and the like can be used, and polypropylene glycol type is more preferably used.

When a prepolymer having a polyol component weight average molecular weight of more than 9000 or an isocyanate group content of less than 3% by mass is used, the polyurethane foam produced may have insufficient foamability and high hardness, and such a prepolymer may have a high viscosity and may be easily mixed with other materials to make mixing difficult and to thereby deteriorate productivity.

On the other hand, when a prepolymer having a weight average molecular weight of the polyol component of less than 3000 or an isocyanate group content of more than 15% by mass is used, the polyurethane foam to be produced may be excessively expanded and may not exhibit good rebound resilience.

The prepolymer is a prepolymer having an isocyanate group at a terminal obtained by reacting a polyol with an isocyanate so that the isocyanate group is excessive (the content of the isocyanate group is 3 to 15% by mass).

The mixing ratio of the polyol component and the isocyanate component may be appropriately determined within the range in which the desired problems of the present invention are achieved, and is preferably adjusted to, for example, an isocyanate index of 0.8 or more and 1.11 or less, and more preferably adjusted to 1.03 or more and 1.07 or less. The polyurethane foam satisfying the isocyanate index in the above range has a small hardness and easily exhibits good rebound resilience. When the isocyanate index is less than 0.8, the modulus of resilience elasticity of the polyurethane foam may not be sufficiently increased, and when it exceeds 1.11, the hardness of the polyurethane foam may not be sufficiently reduced.

The isocyanate index is determined by calculating the equivalent ratio of isocyanate groups contained in the isocyanate component and active hydrogen (isocyanate-reactive hydrogen atoms) contained in the polyol component, which are used in the production of the polyurethane foam.

In the production of the polyurethane foam of the present invention, additives such as a foam stabilizer, a catalyst, a crosslinking agent, and a foaming agent may be suitably used in addition to the above polyol component. Thus, a part or all of the above-described additives may be contained in the polyurethane foam of the present invention.

Foam stabilizer:

the foam stabilizer is used for reacting a polyol component containing a polypropylene glycol system with an isocyanate to cause a urethane reaction, and when the foam is foamed and cured in a mold (forming die), the cell size of the urethane foam is improved. The foam stabilizer is not particularly limited as long as it can be used for producing a urethane foam. The viscosity of the foam stabilizer is preferably 300 to 2000 mPas (25 ℃ C.), more preferably 800 to 1000 mPas (25 ℃ C.) from the viewpoint of easily obtaining good rebound resilience. The foam stabilizer is particularly preferably a silicone compound having the above suitable viscosity range.

If the viscosity of the foam stabilizer is less than 300 mPas (25 ℃), the foam stabilizer may have a weak foam stabilizing action, may have coarse cells, and may not have a high rebound resilience. On the other hand, if the viscosity exceeds 2000mPa · s (25 ℃), there is a risk that: the foam stabilizer is difficult to disperse uniformly in the polyurethane raw material, the cell size of the obtained foam is difficult to be uniform, and the physical properties are locally changed.

When the silicone compound having the above-described suitable viscosity range is used as the foam stabilizer, the silicone compound is preferably used in a range of 0.5 parts by mass or more and 9 parts by mass or less, and more preferably in a range of 0.5 parts by mass or more and 5 parts by mass or less, per 100 parts by mass of the polyol. If the amount is less than 0.5 part by mass, the foam-regulating effect is weak, the cells become coarse, and high resilience cannot be obtained. On the other hand, if it exceeds 9 parts by mass, there is a possibility that bleeding of the foam stabilizer from the surface of the polyurethane foam may occur in addition to the deterioration of the rebound resilience, and handling properties such as inhibition of adhesion to other members may also be deteriorated. By setting the amount of the silicone compound in the above-mentioned suitable viscosity range to 5 parts by mass or less based on 100 parts by mass of the polyol component, a high-quality polyurethane foam can be provided without causing stickiness on the surface of the polyurethane foam.

Catalyst:

the catalyst is not particularly limited as long as it is a catalyst conventionally used for producing a polyurethane foam, and examples thereof include amine catalysts such as triethylenediamine and diethanolamine, and metal catalysts such as bismuth catalyst.

The amount of addition is preferably 0.1 part by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the polyol.

A crosslinking agent:

the crosslinking agent may be any crosslinking agent conventionally used for producing polyurethane foams, and examples thereof include alcohols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, neopentyl glycol, tetramethylene ether glycol, glycerin, pentaerythritol, trimethylolpropane, monoethanolamine, diethanolamine, isopropanolamine, aminoethylethanolamine, sucrose, sorbitol, and glucose. Among them, a crosslinking agent having 3 or more functions is particularly preferable.

Foaming agent:

examples of the blowing agent include water, methylene chloride, cyclopentane, and carbon dioxide.

The amount of water added when used is preferably 0.5 to 3 parts by mass per 100 parts by mass of the polyol.

When the amount of the blowing agent added is less than 0.5 part by mass, there is a risk that foaming becomes insufficient. On the other hand, when the amount of the blowing agent added exceeds 3 parts by mass, foaming proceeds excessively, and the resulting polyurethane foam tends to have a poor foam state such as coarse cells and easy breakage of the inside of the polyurethane foam, and in addition, the rebound resilience tends to be poor.

Other components:

in the raw material of the polyurethane foam of the present invention, the following additives may be used as necessary, in addition to the above-mentioned polyol component and isocyanate component, and optional components such as a crosslinking agent, a blowing agent, a catalyst, a foam stabilizer, and a crosslinking agent. Specifically, one or more additives generally used in the production of polyurethane foams, such as plasticizers, fillers, antioxidants, defoaming agents, compatibilizing agents, coloring agents, stabilizers, and ultraviolet absorbers, may be used within the range in which the effects of the present invention are obtained. Some or all of the additives used may remain in the polyurethane foam of the present invention.

[ Properties of polyurethane foam ]

The polyurethane foam of the present invention described above can provide a polyurethane foam which exhibits a moderately low hardness while maintaining good rebound resilience and is excellent in compression set. The physical properties of the polyurethane foam of the present invention including the above-mentioned contents will be described below.

Modulus of resilience:

in the case where the polyurethane foam of the present invention is used for shoe soles and shoe pads, the modulus of resilience is preferably 50% or more, more preferably 57% or more, and even more preferably 60% or more, from the viewpoint of good push-off and smooth stepping.

On the other hand, in the present invention, the upper limit of the modulus of elasticity in springback is not particularly limited, but is preferably less than 80%, more preferably less than 75%, and still more preferably less than 70%, from the viewpoint of easily achieving a good balance between hardness and mechanical properties.

The modulus of resilience of the polyurethane foam of the present invention is determined in accordance with JIS K6255: 2013 for measurement.

Hardness:

from the viewpoint of exhibiting appropriate flexibility, the hardness of the polyurethane foam of the present invention is preferably 25 or less, more preferably 23 or less, and still more preferably 20 or less. The sole made of polyurethane foam having a hardness of 25 or less has the following effects: the cushion is good, the feeling of walking is good, the burden on the knee and the like during grounding is reduced, and fatigue is not easily felt.

From the viewpoint of maintaining good impact absorbability, the hardness is preferably 10 or more, more preferably 12 or more, and still more preferably 14 or more. If the hardness of the polyurethane foam is too low, walking may become unstable, or the sole of the foot may touch the ground and receive an impact. In the case where the polyurethane foam of the present invention is used as a mat member, the hardness is preferably in the above range.

The hardness of the polyurethane foam of the present invention is measured according to JIS K7312: 1996, measurement using ASKER rubber durometer type C under temperature conditions of 23. + -. 2 ℃.

Among them, in the polyurethane foam of the present invention, it is preferable that the amount of the polyurethane foam is adjusted in accordance with JIS K7312: 1996 and hardness of 10 or more and 25 or less as measured using ASKER rubber durometer C hardness, in accordance with JIS K6255: 2013 has a modulus of elasticity in rebound of 50% or more. The polyurethane foam has a good walking feeling, can favorably absorb the impact when the foot is in contact with the ground, and can reduce the burden on the knee and the like, and therefore, can provide excellent shoe soles and shoe pads which are less likely to cause fatigue.

Compression set:

in addition, from the viewpoint of providing a commercial product having a long product life, the polyurethane foam of the present invention has a foam quality according to JIS K6262: the compression set measured by 2013 is preferably 20% or less, more preferably 19% or less, and further preferably 15% or less.

Here, the polyurethane foam constituting the shoe sole continuously receives a load due to use of the shoe, and intermittently receives an impact due to walking or running, and thus the use environment is severe. Therefore, it is generally difficult to maintain excellent effects such as high rebound elasticity and flexibility of the sole member for a long time. However, a polyurethane foam having a hardness of 10 to 25 inclusive, a modulus of elasticity in resilience of 50% or more, and a compression set of 20% or less is preferable because it can extend the product life of a shoe sole, a cushion material, or a seat member, which is easily subjected to repeated loads.

The compression set is in accordance with JIS K6262: 2013A columnar test piece having a diameter of 29mm and a thickness of 12.5mm was cut out from a polyurethane foam as a test piece for measuring compression set, and the measurement was carried out under the conditions of a compression ratio of 25%, 40 ℃ and 24 hours using this test piece.

Apparent density:

the apparent density of the polyurethane foam of the present invention is not particularly limited, but is preferably 0.15g/cm ³ Above and 0.40g/cm ³ The following ranges.

The apparent density of the polyurethane foam of the present invention is in accordance with JIS K7222: 2005, measurement.

Tensile strength, maximum elongation:

the tensile strength of the polyurethane foam of the present invention is not particularly limited, but is preferably 0.20kPa or more, and more preferably 0.25kPa or more. The maximum elongation of the polyurethane foam of the present invention is not particularly limited, but is preferably 70% or more, more preferably 80% or more, and further preferably 90% or more. If the polyurethane foam exhibits a tensile strength and/or a maximum elongation in the above range, a commercial product having a long product life can be easily provided.

The tensile strength (kPa) and the maximum elongation (%) described above are in accordance with JIS K6400-5: 2012 for the assay. Specifically, the polyurethane foam was cut into pieces of JIS K6400-5: 2012, a test piece was produced with a dumbbell shape of size No. 2, both ends of the test piece were held by a fixture, and the test piece was stretched in the longitudinal direction at a stretching speed of 500 mm/min, and the maximum force at the time of breaking and the distance between the gauge lines were measured to obtain the tensile strength (kPa) and the maximum elongation (%) by the following expressions (1) and (2).

[ formula 1]

Tensile strength (kPa) = (average value of maximum force at break/cross-sectional area before measurement) × 1000

[ formula 2]

Maximum elongation (%) = ((distance between standard lines at break-distance between standard lines before break)/distance between standard lines before break) × 100

Shrinkage property:

the polyurethane foam of the present invention tends to show little or substantially no shrinkage after production, and is excellent in moldability.

The shrinkability as referred to in the present invention means a shrinkage rate immediately after production (shrinkability 1) and a shrinkage rate after curing under predetermined conditions after production (shrinkability 2). The shrinkage factor immediately after production, i.e., the shrinkability 1, of the polyurethane foam of the present invention is preferably 30% or less, more preferably 20% or less, further preferably 5% or less, and particularly preferably substantially 0%. When the polyurethane foam having the shrinkability 1 in the above range is used as a member constituting a laminate by being laminated with another member such as a sole member, dimensional variation with respect to the other member is less likely to occur, and moldability is excellent.

Even when the shrinkage 1 is represented by a significant numerical value, the polyurethane foam of the present invention is preferable because it is judged that the dimensional stability of the product is good if the shrinkage 2 shown after curing is judged to be good.

For the present invention, the shrinkability 1 represents the following shrinkage (%): the polyurethane foam taken out of the mold was rapidly cured under the conditions of a temperature of 23. + -. 2 ℃ and a curing time of 1 hour, and then a shrinkage (%) was calculated from a ratio of a volume calculated from the size of the mold to a volume of the obtained polyurethane foam. When the shrinkage rate is less than 2%, the dimensional stability is judged to be good.

In the present invention, the shrinkability 2 represents the following shrinkage (%): the polyurethane foam confirmed to have a significant shrinkage rate (for example, 2% or more) in the shrinkage property 1 is cured under the conditions of a temperature condition of 23 ± 2 ℃ and a curing time of 48 hours, and then the shrinkage rate (%) is calculated from the ratio of the capacity (volume) calculated from the size of the mold to the capacity (volume) of the cured polyurethane foam. Similarly to the shrinkability 1, if the shrinkage rate after curing is less than 2%, it is judged that the dimensional stability is good.

The polyurethane foam of the present invention explained above can be used for various purposes. Among these, the polyurethane foam of the present invention is preferably used as a sole member, because it exhibits good rebound resilience, is suppressed in hardness, and is excellent in compression set. That is, any part or the whole of the sole of the present invention is configured by using the polyurethane foam of the present invention as described above as a sole member.

[ soles ]

Any part or the whole of the sole of the present invention is constituted using the polyurethane foam of the present invention described above as a sole member.

The shoe sole of the present invention enjoys the preferable effects of the polyurethane foam of the present invention, has a good feel of the sole of the foot, is supported by the kick when walking, facilitates the walking, and reduces the occurrence of accidents such as the knee. Therefore, the shoe having the sole is excellent as various shoes such as sports shoes and general shoes.

The constituent member constituting a part of the shoe sole of the present invention may be the polyurethane foam of the present invention, or the entire shoe sole may be constituted of the polyurethane foam of the present invention. Here, the sole means a sole portion of a shoe, and may be an integral structure or a structure composed of a plurality of members such as an insole, a midsole, and an outsole. For example, one or more members constituting a sole member of a shoe sole, such as an insole, a midsole, and an outsole, may be entirely composed of the polyurethane foam of the present invention, or any part of one member may be composed of the polyurethane foam of the present invention.

For example, a sole using an insole composed entirely of the polyurethane foam of the present invention or an insole composed of the polyurethane foam of the present invention in an arbitrary portion (for example, heel portion) is one of preferable embodiments of the sole of the present invention. The polyurethane foam of the present invention has appropriate rebound resilience and flexibility, and is excellent in compression set, and therefore is suitable as a constituent member of an insole. The sole having the insole has good foot-contact properties, is less likely to give uncomfortable feeling to the sole when wearing shoes, is less likely to accumulate fatigue feeling in the sole even when walking for a long time, and has a long commercial life.

[ Mat Material ]

The polyurethane foam of the present invention can also be suitably used as a constituent member of a mat. That is, the polyurethane foam of the present invention exhibits excellent rebound resilience, is suppressed in hardness, and is excellent in compression set, and therefore, it exhibits excellent effects also in a mat, particularly a floor mat.

When a mat made of the polyurethane foam of the present invention is laid on the ground and a long-term work, walking, standing, or the like is performed thereon, accumulation of fatigue can be reduced.

[ examples ] A method for producing a compound

A solution a containing a polyol component, a foam stabilizer, a catalyst and ion-exchanged water was prepared in the proportions shown in tables 1 and 2. Further, a B liquid containing a urethane prepolymer and/or a carbodiimide-modified diphenylmethane isocyanate (modified MDI) as an isocyanate component was prepared.

The polyol component in solution a and the isocyanate component in solution B were adjusted so that the amount of the isocyanate component blended with 100 parts by mass of the polyol component and the isocyanate index became values shown in tables 1 and 2, and solution a and solution B were poured into a mold. Then, after allowing to react at a mold temperature of 40 ℃, the polyurethane foam was obtained by demolding.

The units of the numerical values indicating the compounding ratios of the components contained in the solutions a and B shown in tables 1 and 2 are parts by mass.

< polyol component >

The polypropylene glycol systems 1 to 9 (PPG 1 to 9) as the polyol components used in the examples and comparative examples are all polyoxyethylene polyoxypropylene glycols as follows. The individual weight average molecular weights, numbers of functional groups, and equivalent weights of the PPGs 1 to 9 are shown in tables 1 and 2.

In the table, the polypropylene glycol system is referred to as PPG, one or more polypropylene glycol systems (polypropylene glycol system group) are referred to as PPG group, and the weight average molecular weight is referred to as Mw.

PPG1: SANNIX KC-737, manufactured by Sanyo chemical industries, ltd

PPG 2: SANNIX KC-285, manufactured by Sanyo chemical industries, ltd

PPG3: EXCENOL 837, manufactured by AGC K.K

PPG4: EXCENOL 510, manufactured by AGC corporation

PPG5: EXCENOL 820, manufactured by AGC corporation

PPG6: sanyo chemical industry Co., ltd, SANNIX PA-3000

PPG7: EXCENOL 3030F2, manufactured by AGC corporation

PPG8: ACTCOL D2000, manufactured by SKC polyurethane Co., ltd, mitsui chemical

PPG9: PREMINOL S3011, manufactured by AGC corporation

< foam stabilizer >

Silicone-based compound: viscosity: 900 mPas (25 ℃ C.)

< catalyst >

Amine-based catalyst: triethylene diamine (trade name TEDA-L33, manufactured by Tosoh Co., ltd.)

< blowing agent >

Ion exchange water

< isocyanate component >

Isocyanate (ii): carbodiimide-modified diphenylmethane isocyanate (modified MDI), average functional group number 2, isocyanate group content 28.2% by mass

Urethane prepolymer: isocyanate terminated prepolymer (prepolymer obtained by reacting PPG having a weight average molecular weight of 4000 with 4,4' -MDI, isocyanate group content of 8.01% by mass)

The arithmetic mean of the numbers of functional groups of the polypropylene glycol group (PPG group) used in each example and each comparative example, that is, the average number of functional groups as a whole was calculated. In the same manner, the arithmetic average of the equivalent weights of the polypropylene glycol group (PPG group) used in each example and each comparative example, that is, the average equivalent weight of the whole was calculated. The weight average molecular weight (Mw) of the whole PPG group was calculated from the weight average molecular weight and the blending ratio of each polypropylene glycol alone. The values calculated as described above are shown in tables 1 and 2.

The polyurethane foams obtained in the examples and comparative examples were cut into appropriate sizes to prepare test pieces, and the following measurements were performed. The measurement results are shown in tables 1 and 2.

Using a test piece cut into a rectangular parallelepiped of 15 mm. Times.15 mm. Times.10 mm, the thickness of the specimen was measured in accordance with JIS K7222: the apparent density is measured 2005.

< ASKER C hardness >

Using a test piece cut to a thickness of 12.5mm, according to JIS K7312: 1996, hardness of polyurethane foam (ASKER C hardness) was measured using ASKER rubber durometer type C.

< elastic modulus of Resilience (%) >

Using a test piece cut to a thickness of 12.5mm, the thickness was measured in accordance with JIS K6255: 2013, the modulus of elasticity in springback was measured.

< tensile Strength, maximum elongation >

According to JIS K6400-5: 2012, the tensile strength (kPa) and elongation (%) of the polyurethane foam are measured. Specifically, the polyurethane foam was cut into pieces of JIS K6400-5: 2012, a test piece was prepared by holding both ends of the test piece between fixtures, stretching the test piece in the longitudinal direction at a stretching speed of 500 mm/min, and the maximum force at the time of fracture and the inter-reticle distance were measured and obtained by the following (formula 1) and (formula 2).

[ formula 1]

Tensile strength (kPa) = (maximum force at break/average value of cross-sectional area before measurement) × 1000

[ formula 2]

< compression set >

A test piece in the form of a cylinder having a diameter of 29mm and a thickness of 12.5mm was cut out from the polyurethane foam and used as a test piece for measuring compression set. The compression set of the test piece was measured, and the compression ratio was 25%, 40 ℃ and 24 hours according to JIS K6262: 2013, the compression set (%) was measured.

< shrinkage Property >

Shrinkage 1:

the polyurethane foam was taken out from the mold (mold), and the volume V1 was calculated from the outer dimensions and mass of the polyurethane foam cured at a temperature of 23. + -. 2 ℃ for 1 hour. Then, using the volume V1 and the capacity (volume) V2 of the mold, the shrinkage ratio was calculated by the following (formula 3) and was regarded as the shrinkability 1. In the shrinkability 1 in tables 1 and 2, the shrinkage factor is 0% when it is less than 2%, and the value is 0% when it is 2% or more. In addition, the above numerical range of less than 2% includes 0%.

[ formula 3]

Shrinkage (%) = [ (V2-V1)/V2 ] × 100

Shrinkage 2:

the polyurethane foam having a shrinkage of 2% or more in the shrinkability 1 was cured under the conditions of a temperature of 23. + -. 2 ℃ and a curing time of 48 hours. The volume V3 was calculated from the external dimensions and mass of the cured polyurethane foam. Then, the shrinkage (%) was calculated by the following (formula 4) using the volume V3 and the capacity (volume) V2 of the mold, and evaluated according to the following evaluation criteria.

In addition, in the case where the shrinkage ratio is less than 2% in the shrinkability 1, the shrinkability 2 is not measured, and thus it is expressed as n.t. (not tested).

[ formula 4]

Shrinkage (%) = [ (V2-V3)/V2 ] × 100

(evaluation criteria)

Good contractibility, 8230and contractibility less than 2%

Shrinkage of 2% or more

Industrial applicability

The polyurethane foam of the present invention is excellent in resilience, low in hardness, and excellent in compression set. Accordingly, the polyurethane foam of the present invention is suitable as a sole member or a cushion member. In particular, the polyurethane foam of the present invention is more preferable as an insole member of footwear. In addition, the polyurethane foam of the present invention can be widely used in applications requiring impact absorption, rebound resilience, appropriate flexibility, good mechanical strength, and the like, such as a cushion member, an interior member of a helmet, a protector, a cushion material for a vehicle, a floor material, and the like.

As described above, the polyurethane foam of the present invention, which exhibits excellent effects, can be used not only in the technical fields of shoes and shoe pads, but also in various technical fields in which the excellent properties are effectively utilized.

The present invention described above includes the following technical ideas.

(1) A polyurethane foam characterized in that,

the polyurethane foam comprises a polyol component and a polyisocyanate component,

the polyol component contains at least one polypropylene glycol-based polyol,

the one or more polypropylene glycol-based polymers contain, in a range of less than 50 mass% (including 0), a polypropylene glycol-based polymer having a weight average molecular weight of 4000 or less alone, out of 100 mass% of the total of the one or more polypropylene glycol-based polymers,

the weight average molecular weight of the whole of the one or more polypropylene glycol is 4000 to 9000,

the average number of functional groups of the whole of the one or more polypropylene glycol-based polymers is 2.50 or more and 4.00 or less,

the average equivalent weight of the one or more polypropylene glycol-based polymers as a whole is 1600 to 2500 inclusive.

(2) The polyurethane foam according to the above (1), wherein,

according to JIS K7312: 1996, hardness of 10 or more and 25 or less as measured by using an ASKER rubber durometer C hardness scale,

according to JIS K6255: 2013 has a modulus of elasticity in rebound of 50% or more.

(3) The polyurethane foam according to the above (1) or (2), wherein the ratio of the amount of the polyurethane foam according to JIS K6262: 2013 has a compression set of 20% or less.

(4) The polyurethane foam according to the above (1) or (2), wherein the polyol component contains at least one polypropylene glycol based material in an amount of 90% by mass or more based on 100% by mass of the polyol component.

(5) The polyurethane foam according to the above (1) or (2), wherein the isocyanate index is 0.8 or more and 1.11 or less.

(6) A shoe sole characterized in that any part or the whole of the shoe sole is constituted by using the polyurethane foam according to the above (1) or (2) as a sole member.

Claims

1. A polyurethane foam characterized in that,

the polyol component contains at least one polypropylene glycol-based polyol,

the one or more polypropylene glycol-based polymers are contained in an amount of less than 50% by mass in a total of 100% by mass, wherein the amount of the one or more polypropylene glycol-based polymers is 0,

the average number of functional groups of the one or more polypropylene glycol groups is 2.50 or more and 4.00 or less,

2. The polyurethane foam according to claim 1,

according to JIS K6255: 2013, and the elastic modulus of resilience is 50% or more.

3. The polyurethane foam according to claim 1 or 2, wherein the weight ratio is in accordance with JIS K6262: 2013, and the compression set ratio is 20% or less.

4. The polyurethane foam according to claim 1 or 2, wherein the polyol component contains at least one polypropylene glycol based material in an amount of 90 mass% or more based on 100 mass%.

5. The polyurethane foam according to claim 1 or 2, wherein an isocyanate index is 0.8 or more and 1.11 or less.

6. A shoe sole characterized in that any part or whole of the shoe sole is constructed using the polyurethane foam according to claim 1 or 2 as a sole member.