JP2864493B2 - Insole for shoes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an insole for shoes, and particularly to rubber shoes such as leather shoes (men's shoes, women's shoes), sports shoes, chemical shoes, and sandals. The present invention relates to an insole for shoes suitable for an insole material. [Prior Art] Conventionally, leather shoes generally have a flat bottom surface. On the other hand, in sports shoes such as tennis and jogging, insoles (insoles) shaped according to the three-dimensional structure of the foot are often arranged on a flat insole board, but the insole shape is flat. Was common. On the other hand, in recent years, insoles corresponding to the three-dimensional shape of the sole have been developed, and high-quality leather shoes (men's shoes, women's shoes), sneakers,
It is applied to sandals and the like. These insoles generally consist of a molded product in which a lightweight filling material such as cork is mixed with rubber and an insole board. [Problems to be Solved by the Invention] The shoes having a flat bottom as described above do not have a sufficient fit to the foot, are inferior in stability when walking, and are easily tired when walking for a long time. If the shoe adopts the midsole corresponding to the three-dimensional shape of the sole, the fit is ensured to some extent. However, the conventional insole consists of a molded product in which a lightweight filler such as cork is blended with rubber, and this molded product is not sufficiently lightweight. There is also a disadvantage that the effect of preventing fatigue during long-time walking is low because it is not sufficient. Further, since cork compound rubber is vulcanized and molded, there is a disadvantage that the processing time is long, the productivity is inferior, and the cost is high. Thus, conventionally, it has a three-dimensional shape against the sole,
And because it is not shock absorbing, lightweight and inexpensive insole is not provided, it has good fit with the foot, good stability when walking, and it is difficult to manufacture shoes with less fatigue even when walking for a long time. there were. Means for Solving the Problems The present invention solves the above-mentioned conventional problems, and provides an insole for shoes that is excellent in shock absorption and light weight and is inexpensive. A shoe insole made by backing a molded article of foam for use with an insole board, wherein the foam for shock absorption comprises: an ethylene-vinyl acetate copolymer having a vinyl acetate content of 26% by weight or less, 30 to 80% by weight. %, A syndiotactic 1,2-polybutadiene 5 to 40% by weight, and a polymer component containing a high loss material having a rebound resilience at 25 ° C. of 20% or less 10 to 40% by weight. Is 0.05 to 0.6, and is a foam that can be formed afterwards. Hereinafter, the present invention will be described in detail. The insole for shoes of the present invention is excellent in shock absorption, and is formed from a foam form that can be formed later by pressing or the like into a shape corresponding to the three-dimensional shape of the sole, and this is fixed on the insole board. Easily manufactured. The degree of compression during press molding of the foam foam for impact absorption is preferably 1.5 to 5 times, and preferably about 2 to 5 times the initial thickness. Adhesion between the molded article of the shock absorbing foam and the insole board can be performed by a conventional method, for example, by bonding with an organic adhesive such as a neoprene adhesive. The bonding may be performed before forming the shock absorbing foam, or may be performed simultaneously with the press forming. A shank or a plate made of a metal or a composite material such as a carbon fiber reinforced resin (CFRP) can be disposed on the midsole of the present invention as necessary. By the way, conventionally, relatively cheap and lightweight ethylene-vinyl acetate copolymer (EVA) is often used for shoe soles and middle soles in order to reduce the impact on the foot during exercise or walking. However, while EVA foam is lightweight and inexpensive, it has the following disadvantages when used as a shoe insole or as a member for cushioning impact. Low hardness products have low shock absorption performance. Even with high hardness products, there is a problem in performance against strong impact. There is a problem in durability of shock absorption performance. On the other hand, high-styrene SBR-based and polynorbornene-based materials are also known as foam rubbers having particularly excellent impact absorption properties, and they are used as shoe bottom materials, but all have the drawback that they cannot be post-molded. As a shock absorbing foam for midsole for shoes, it is lightweight and inexpensive, and has excellent shock absorbing performance against a wide range of impact forces,
Moreover, it is required that the durability for long-time use is extremely high. In the present invention, the shock absorbing foam can satisfy such required characteristics. The following materials are used. That is, 30-80% by weight of ethylene-vinyl acetate copolymer having a vinyl acetate content of 26% by weight or less, 5-40% by weight of syndiotactic 1,2-polybutadiene, and a rebound resilience at 25 ° C. of 20% or less. A polymer component containing 10 to 40% by weight of a high-loss material is foamed, has a specific gravity of 0.05 to 0.6, and is made of a material that can be post-formed by hot pressing or the like. Among the polymer components of the shock absorbing foam, ethylene-
When the vinyl acetate content of the vinyl acetate copolymer (hereinafter may be abbreviated as "EVA") is 26% by weight or less, the energy absorption performance is relatively high. The preferred vinyl acetate content of the EVA is 10-20% by weight. In addition, syndiotactic 1,2-polybutadiene (hereinafter may be abbreviated as “1,2-PBD”) improves permanent set resistance and improves durability of shock absorption performance. it can. Further, as a high-loss material having a rebound resilience at 25 ° C. of 20% or less (hereinafter sometimes abbreviated as “high-loss material”),
Although not particularly limited, a styrene-butadiene copolymer rubber having a high styrene content (hereinafter may be abbreviated as "high styrene-SBR"), a styrene-isoprene copolymer rubber having a high styrene content, and acrylonitonyl-butadiene having a high acrylonitrile content. Copolymer rubber (hereinafter sometimes abbreviated as “extremely high nitrile-NBR”), polyvinyl chloride,
Norbornene-based rubbers are preferred, and these can be used alone, mixed or oil-extended. These high-loss materials have even greater energy absorption performance than EVA and are effective in improving the impact absorption performance of the resulting foam. The foam used in the present invention contains these polymer components as EVA3
0-80 wt%, 1,2-PBD5-40 wt%, high loss material 10-40
It is assumed that the mixture is blended at a ratio of weight% and foamed. Among these polymer components, EVA acts on high foaming properties. EVA
If the content is less than 30% by weight, the foaming property is deteriorated and high foaming property cannot be obtained. On the other hand, when the EVA exceeds 80% by weight, the impact absorption performance of the obtained foam decreases. If 1,2-PBD is less than 5% by weight, the resulting foam will not have sufficient durability for impact absorption, and if it exceeds 40% by weight, the impact absorption and foaming properties will be poor. When the amount of the high-loss material is less than 10% by weight, the effect of improving the impact absorption of the obtained foam is small, and when the amount exceeds 40% by weight, the foamability deteriorates. In the present invention, particularly preferred compounding ratios of the polymer components are 40 to 50% by weight of EVA, 20 to 30% by weight of 1,2-PBD, and 25 to 35% by weight of a high-loss material. The impact-absorbing foam suitable in the present invention is, if necessary, a filler such as calcium carbonate, carbon black, silica and other inorganic fillers, a plasticizer, an oil, a foaming agent, and a foaming agent. It is obtained by adding an auxiliary agent, a peroxide and the like, and heating and foaming and curing according to a conventional method. The specific gravity is preferably 0.05 to 0.6. When the specific gravity exceeds 0.6, the lightness is impaired, and when the specific gravity is less than 0.05, sufficient impact absorption and strength cannot be obtained. In addition, the preferable compounding ratio at the time of producing the shock absorbing foam of the present invention is as follows. 100 parts by weight of the polymer component, 25 fillers, 3.5 foaming agents, 1.5 peroxides, and foaming conditions are preferably 155 to 165 ° C. for about 13 to 17 minutes. [Function] The foam, which is formed into a shape corresponding to the three-dimensional shape of the sole and has excellent shock absorbing properties, is lightweight, has good fit with the foot when used as shoes, and has excellent shock absorbing properties. In addition, it gives shoes excellent performance, which has not been achieved in the past, such that they do not get tired even when walking for a long time. Also, the use of the insole board makes it easier to hang the upper when manufacturing shoes, making it possible to use the conventional shoe manufacturing technology as it is, and is effective in reducing the cost of the final product shoes It is. [Examples] Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples as long as the gist is not exceeded. Example 1, Comparative Example 1 The polymer components and other additives were mixed in the proportions shown in Table 1 and foamed and cured by heating at 160 ° C. for 10 minutes to obtain a foam having a specific gravity shown in Table 1. The foams shown in Table 1 were molded in a mold containing an insole board under the conditions of 100 ° C x 5 minutes, demolded at 40 ° C, and the three-dimensional shape corresponding to the unevenness of the soles as shown in Fig. 1 The middle sole (for 26 cm) 4 for men's shoes having the following was manufactured. The foam molded article 1 and the insole board 2 were bonded using a neoprene-based adhesive and partially bonded via a shank 3 as shown in FIG. The thickness of each part of the midsole after press molding was as shown in FIG. 1, and the maximum compression ratio was about 3 times. Separately, a conventional insole using cork-filled rubber (Comparative Example 1) was prepared, and shock absorption and weight were measured and compared. The results are shown in Table 2 below. In addition, the shock absorption was examined by obtaining a shock acceleration by a falling bell impact test shown in FIG. That is, the sample 11 is placed on the iron base 10, the weight 12 is dropped on the sample 11 from the drop height h, and the impact acceleration at that time is measured by the accelerometer 13. The greater the shock absorption, the lower the acceleration. The test conditions were as follows. Weight: 5 kg Contact surface: 9 cm ² Drop height h: 10 cm Example 2, Comparative Examples 2 and 3 In the same manner as in Example 1, a midsole (for 23 cm) for women's sandals as shown in FIG. 3 was manufactured. did. The thickness of each part is as shown in FIG. Separately, an insole using rubber sponge (Comparative Example 2) and an insole using cork-filled rubber (Comparative Example 3) were prepared, and the impact absorption performance and weight were measured and compared in the same manner as in Example 1. The results are shown in Table 2. From Table 2, it is clear that the insole for shoes of the present invention is lightweight and excellent in shock absorption. In addition, using the insole 4 manufactured in Example 1, a gentleman's leather shoe as shown in FIG. 2 was produced, and using the insole 5 manufactured in Example 2 as shown in FIG. When ladies' sandal shoes were prepared and used by the testers, they were all evaluated highly because they were lightweight, had good fit to the feet, and were hardly tired. [Effects of the Invention] As described in detail above, the insole for shoes of the present invention is formed by backing a molded article of a foam for absorbing shock with an insole board, and is low cost, lightweight, and extremely excellent. Has shock absorbing performance. Therefore, according to the shoe midsole of the present invention, it is possible to manufacture shoes that are inexpensive, have excellent fit to the foot, are high-performance, are not easily fatigued, and have a long life.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of the midsole manufactured in Example 1, and FIG. 2 is a perspective view showing the inside of a shoe manufactured using the midsole of FIG. FIG. 3 is a sectional view of the midsole manufactured in Example 2, and FIG. 4 is a perspective view showing the inside of a shoe manufactured using the midsole of FIG. FIG. 5 is a side view showing the shock absorption test method. 1 ... molded article of shock absorbing foam, 2 ... insole board, 3 ... shank, 4, 5 ... insole.

Continuation of the front page (56) References JP-A-61-71002 (JP, A) JP-A-56-132909 (JP, U) JP-A-61-139606 (JP, U) JP-A-61-149501 (JP) (58) Fields investigated (Int. Cl. ⁶ , DB name) A43B 13/38 A43B 13/04 A43B 13/40

Claims (1)

(57) [Claims] An insole for shoes formed by backing a molded article of a shock absorbing foam with an insole board, wherein the shock absorbing foam comprises: an ethylene-vinyl acetate copolymer having a vinyl acetate content of 26% by weight or less. 80% by weight, 5 to 40% by weight of syndiotactic 1,2-polybutadiene and 10 to 40% by weight of a high-loss material having a rebound resilience at 25 ° C. of 20% or less are foamed to form a polymer component, An insole for shoes, having a specific gravity of 0.05 to 0.6, and a foam which can be formed later. 2. The midsole for shoes according to claim 1, wherein the post-molding is press molding, and the degree of compression at that time is 2 to 5 times that of the foam before molding. 3. The molded article of the shock absorbing foam has a three-dimensional shape corresponding to the unevenness of the sole of the foot.
Item 3. The shoe insole according to item 2 or 2.