JP2006264637A - Polyurethane composition and solid tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyurethane composition and a solid tire capable of suppressing slip on a road surface of low friction coefficient while sufficiently exhibiting physical property of the polyurethane resin. <P>SOLUTION: The polyurethane composition is constituted by mixing silicone oils with polyurethane prepolymer, i.e., a matrix material. The silicone oil is at least one kind selected from dimethylsiloxane, methylhydrodienesiloxane and modified siloxane in which an organic group is introduced to the dimethylsiloxane. The polyurethane composition is a composition for forming a tread part of the solid tire and the solid tire is a tire in which an outer peripheral surface of a wheel is covered by the tread part. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polyurethane composition for forming a tread portion of a solid tire and a solid tire having a tread portion formed from the polyurethane composition.

Conventionally, this type of solid tire has been used in applications such as wheels for industrial vehicles such as automatic guided vehicles and forklifts, rollers for automatic warehouses, multilevel parking lots, various manufacturing facilities, and rollers for roller coasters. (For example, refer to Patent Document 1). The solid tire includes a wheel and a tread portion that covers an outer peripheral surface of the wheel. As the material of the tread portion, polyurethane resin is widely used because the durability (abrasion resistance) of the tread portion is good. In general, in a solid tire having a tread portion made of polyurethane resin, since the friction coefficient of polyurethane resin is low, slip is likely to occur between the tread surface of such a solid tire and a road surface covered with water or oil, for example. . In view of this, conventionally, solid tires having a burial embedded in a polyurethane resin have been proposed. In this solid tire, the slip on the road surface is suppressed by a part of the collar exposed from the tread surface serving as a spike in the spike tire.
JP 2004-161042 A

  By the way, the above conventional solid tires with slips are excellent in slip suppression effect on road surfaces that are easily slipped by water or oil, but are durable due to damage to the stains themselves or stress concentrated on the polyurethane resin holding the stains. Sufficient sex cannot be obtained. That is, in the conventional solid tire, when it is configured to suppress slip on a road surface (road surface with a low friction coefficient) covered with water or oil, physical properties such as durability inherent in the polyurethane resin are impaired.

  The present invention has been made in view of such conventional circumstances, and the object thereof is to provide a polyurethane composition and a solid that can suppress slip on a road surface having a low friction coefficient while sufficiently exerting the physical properties of the polyurethane resin. To provide tires.

  In order to achieve the above object, the polyurethane composition of the invention according to claim 1 is a polyurethane composition for molding the tread portion of a solid tire comprising a wheel and a tread portion covering an outer peripheral surface of the wheel. Silicone oils are blended with a polyurethane prepolymer as a base material, and the silicone oils are dimethylsiloxane, methylhydrogensiloxane, and modified siloxane having an organic group introduced into the dimethylsiloxane. The summary is that it is at least one selected from

The gist of the invention described in claim 2 is that, in the polyurethane composition according to claim 1, at least dimethylpolysiloxane is blended as the silicone oil.
The invention according to claim 3 is that in the polyurethane composition according to claim 1 or 2, 0.1 to 10 parts by mass of the silicone oil is blended with 100 parts by mass of the polyurethane prepolymer. The gist.

  The gist of the solid tire according to claim 4 is that it has the tread portion formed by curing the polyurethane composition according to any one of claims 1 to 3.

  ADVANTAGE OF THE INVENTION According to this invention, the slip on the road surface of a low friction coefficient can be suppressed, fully exhibiting the physical property of a polyurethane resin.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments embodying the present invention will be described in detail.
The polyurethane composition is constituted by blending silicone oils with a polyurethane prepolymer as a base material. Silicone oils are at least one selected from dimethylsiloxane, methylhydrogensiloxane, and modified siloxane having an organic group introduced into dimethylsiloxane. This polyurethane composition is a composition that is a raw material for molding a tread portion in a solid tire including a wheel and a tread portion that covers the outer peripheral surface of the wheel.

  The polyurethane prepolymer is contained as a matrix (matrix) of the polyurethane composition. This polyurethane prepolymer is a polymer which contains a polyol and an isocyanate as main components and serves as a raw material for molding a molded body made of a polyurethane resin. More specifically, the polyurethane prepolymer is a polymer in which a polymerization reaction between a polyol and an isocyanate proceeds to a predetermined stage, and is set to a viscosity suitable for injection into a molding die. This polyurethane prepolymer is cured by the action of heat or a chain extender (curing agent) separately blended to form a polyurethane resin molded body.

  Examples of the polyol constituting the polyurethane prepolymer include ether polyols such as polypropylene glycol (PPG) and polytetramethylene glycol (PTMG), ester polyols such as adipate polyols, polycaprolactone polyols and polycarbonate polyols. . Examples of the isocyanate constituting the polyurethane prepolymer include tolylene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), 1,5-naphthalene diisocyanate (NDI), p-phenylene diisocyanate (PPDI), and the like. The polyurethane prepolymer composed of these polyols and isocyanates may be used alone or in a blend of a plurality of types of polyurethane prepolymers. In addition, from the viewpoint that the obtained polyurethane resin has excellent durability, the polyol of the polyurethane prepolymer is preferably an ether-based polyol, and a polyurethane prepolymer composed of PTMG and TDI is preferable.

  Silicone oils are components that modify the surface of a tread portion molded from a polyurethane composition, and specifically, are components that are blended to suppress slippage of the tread portion with respect to a road surface having a low friction coefficient. These silicone oils are compounds having a siloxane structure, and include dimethylsiloxane, methylhydrogensiloxane, and modified siloxane. The dimethylsiloxane includes dimethylpolysiloxane having a repeating unit having a siloxane structure. The methyl hydrogen siloxane includes dimethyl hydrogen polysiloxane having a repeating unit having a siloxane structure. Modified siloxane refers to dimethylsiloxane modified with an organic group introduced into the side chain, one end, both ends, or both side chain and both ends of dimethylsiloxane. The modified siloxane includes modified polysiloxane obtained by modifying dimethylpolysiloxane with an organic group. The organic group of the modified siloxane is amino group, epoxy group, carboxyl group, carbinol group, methacryl group, mercapto group, phenol group, polyether group, methylstyryl group, alkyl group (excluding methyl group), or fluorine. Contains groups.

  These silicone oils may be blended singly or in combination of a plurality of types. Among silicone oils, in addition to the wet road surface covered with water or the like, it is preferable to blend at least dimethylpolysiloxane having a repeating unit of a siloxane structure from the viewpoint of increasing the coefficient of friction with respect to a dry dry road surface, It is more preferable to blend only this dimethylpolysiloxane.

The kinematic viscosity at 25 ° C. of the silicone oil is preferably 0.5 to 3000 (mm ² / s), more preferably 0.5 to 1000 (mm ² / s), and further preferably 0.5 to 500 (mm). ² / s). When this kinematic viscosity is less than 0.5 (mm ² / s), when the polyurethane prepolymer is cured while heating the polyurethane composition, the silicone oil is easily volatilized, and the performance commensurate with the blending amount is obtained. It may be difficult to obtain. On the other hand, when it exceeds 3000 (mm ² / s), there is a possibility that it is difficult to obtain a sufficient coefficient of friction for the dry road surface. The kinematic viscosity may be adjusted by blending silicone oils having different kinematic viscosities.

  The amount of silicone oil blended is preferably 0.1 to 10 parts by weight, more preferably 1 to 10 parts by weight, even more preferably 3 to 8 parts by weight, in terms of the amount blended with respect to 100 parts by weight of the polyurethane prepolymer. is there. When this compounding quantity exceeds 10 mass parts, there exists a possibility that the physical property of the polyurethane resin obtained, especially durability may become difficult to be obtained sufficiently. On the other hand, if it is less than 0.1 part by mass, the slip suppression effect may not be sufficiently obtained.

  When the silicone oil is blended with the polyurethane prepolymer, it is preferable that the silicone oil is sufficiently mixed and dispersed in the polyurethane prepolymer. For mixing and dispersing of these silicone oils, a known stirring device represented by a stirring device (agitator) that stirs with a blade can be used. Moreover, it is preferable that air bubbles contained in the polyurethane composition are sufficiently removed before the curing reaction of the polyurethane composition. For the removal of bubbles, that is, defoaming, a defoaming / mixing device utilizing the principle of centrifugal separation, or a vacuum / stirring device capable of stirring in a vacuum can be used.

  The obtained polyurethane composition preferably contains a chain extender (curing agent) in order to accelerate the curing reaction of the polyurethane prepolymer and to control the physical properties of the resulting polyurethane resin. This chain extender promotes the polymerization reaction of the polyurethane prepolymer and serves to extend the polymer chain. What is necessary is just to set the kind and compounding quantity of a chain extender according to the kind of polyurethane prepolymer. Examples of chain extenders include diamines such as 3,3′-dichloro-4,4′-diaminodiphenylmethane (MOCA), 1,4-butanediol (1,4BD), hydroquinone dioxyethyl ether (HQEE), and the like. Diols and the like. This chain extender can be added to the polyurethane prepolymer before the silicone oil is added to the polyurethane prepolymer. Here, when the silicone oil is blended after blending the chain extender, the curing reaction of the polyurethane prepolymer proceeds when the silicone oil is mixed and dispersed in the polyurethane prepolymer. That is, the viscosity of the polyurethane prepolymer increases, and it may be difficult to sufficiently mix and disperse the silicone oil in the polyurethane prepolymer. In this regard, if a chain extender is blended after blending the silicone oil with the polyurethane prepolymer, the silicone oil can be sufficiently mixed and dispersed in the polyurethane prepolymer.

  In order to manufacture a solid tire using a polyurethane composition as a raw material, a core metal to be a wheel of the solid tire is inserted into a cavity of a mold, and the polyurethane composition is injected into the cavity. The material of the core bar is not particularly limited, and examples thereof include iron, aluminum, and stainless steel. Subsequently, the polyurethane composition is cured by heating the mold for a predetermined time. Then, a polyurethane resin that is a cured product of the polyurethane composition is obtained, and a tread portion made of the polyurethane resin is molded. At this time, the tread portion is formed integrally with a core metal (wheel) inserted into the cavity. Finally, by removing the tread portion and the core metal (wheel) from the cavity, a solid tire in which the tread portion is integrated with the core metal (wheel) can be obtained.

  This solid tire is composed of a cylindrical wheel and a tread portion that covers the outer peripheral surface of the wheel. Wheels of industrial vehicles such as automatic guided vehicles and forklifts, automatic warehouses, multistory parking lots, various manufacturing facilities, etc. It is used for applications such as transport rollers and roller coaster wheels. At this time, since the tread portion of the solid tire is molded from the polyurethane composition, the surface of the polyurethane resin tread portion is modified with silicone oils. These silicone oils are components that are excellent in the action of modifying the surface of the tread portion while sufficiently exhibiting the physical properties inherent to the polyurethane resin. The tread portion modified with such silicone oils has a high friction coefficient on a road surface with a low friction coefficient, for example, a road surface covered with water or oil. In particular, this tread portion is excellent in the effect of increasing the friction coefficient with respect to the road surface covered with water and the road surface of ice in the freezer. This effect is presumed to improve the adhesion between the polyurethane resin and the road surface due to the water repellency of the silicone oil involved in the water covering the road surface.

  In the tread portion, a grooved tread pattern may be formed on the tread surface that comes into contact with the road surface, but the polyurethane composition of the present embodiment has sufficient durability and the like inherent in the polyurethane resin. It is effective to apply to a tread portion where a tread pattern is not formed. That is, by applying to a solid tire having no tread pattern, the slip suppression effect can be continuously exhibited without being affected by the groove that decreases with the running time.

  On the other hand, in recent years, interest in food hygiene, such as processed fishery products, has increased, and measures for food hygiene in factories and warehouses that handle such food have become necessary. In conventional solid tires with mites, there is a concern that the generation of dust due to mites scraping the road surface and a part of the mites that have dropped off may affect such food hygiene. In this regard, according to the solid tire of the present embodiment, the durability inherent in the polyurethane resin is maintained, so that the influence on hygiene can be reduced as much as possible.

The effects exhibited by this embodiment will be described below.
(1) Since silicone oils are blended in the polyurethane composition, it is possible to obtain a tread portion having an increased friction coefficient with respect to a road surface having a low friction coefficient (for example, a road surface covered with water or oil). become. Silicone oils hardly affect the physical properties (durability, etc.) inherent to the polyurethane resin obtained from the polyurethane composition. Therefore, it is possible to suppress slip on the road surface having a low coefficient of friction while fully exhibiting the physical properties of the polyurethane resin.

  (2) By adding at least dimethylpolysiloxane as the silicone oil, it is possible to increase the coefficient of friction with respect to the dry dry road surface in addition to the wet road surface covered with water or the like. For this reason, the polyurethane composition more effective in the slip suppression effect can be provided.

  (3) Providing a polyurethane composition that exhibits a good balance between durability maintenance and slip suppression effect by blending 0.1 to 10 parts by mass of silicone oil with 100 parts by mass of polyurethane prepolymer. it can.

  (4) The solid tire formed by curing the polyurethane composition can exhibit durability and a slip suppression effect in various applications. In particular, this solid tire can reduce the impact on hygiene as much as possible, so its use value is extremely high in environments where there are concerns about hygiene such as factories and warehouses that handle food products such as processed fishery products. high.

Next, the technical idea that can be grasped from the above embodiment will be described below.
(A) The polyurethane composition according to any one of claims 1 to 3, wherein the silicone oil has a kinematic viscosity at 25 ° C of 0.5 to 3000 (mm ² / s).

  (B) The polyurethane prepolymer is a polyurethane composition according to any one of claims 1 to 3 and (a), which is composed of an ether-based polyol and an isocyanate.

Next, the embodiment will be described more specifically with reference to examples and comparative examples.
(Examples 1-3)
Polyurethane composition by blending dimethylpolysiloxane (kinematic viscosity 5 mm ² / s at 25 ° C.) with polyurethane prepolymer (composed of PTMG and TDI), and mixing and dispersing dimethylpolysiloxane in polyurethane prepolymer Was prepared. The amount of each component is as shown in Table 1. In Table 1, dimethylpolysiloxane is indicated by (A).

  A polyurethane resin molded product was obtained by blending 12.6 parts by mass of a chain extender (MOCA) to the polyurethane composition of each Example and curing the polyurethane composition by heating. Table 1 shows the static physical properties of the molded body of each example.

  Furthermore, a test piece was produced from the molded body of each example, and a wear test was performed on the test piece. This wear test is shown in Table 1 as a result of the Akron wear test described in JIS K 6264 conducted under the following conditions.

Test method: Method A-1 Load load: 4.5 kgf
Tilt between test piece and wear ring: 30 °
Rotation speed of test piece: 250 rpm
In addition, test pieces were prepared from the molded bodies of the respective examples, and the static friction coefficient and the dynamic friction coefficient were measured for these test pieces using a friction measuring machine (TR type) manufactured by Toyo Seiki Seisakusho Co., Ltd. In addition, each friction coefficient was measured with respect to iron (dry surface and wet surface) and concrete (dry surface and wet surface). The measurement results are shown in Table 1.

(Comparative Example 1)
A polyurethane resin molded article was produced in the same manner as in Examples 1 to 3, except that dimethylpolysiloxane was not blended. Table 1 shows the results of the measurement of the static physical properties, the wear test, and the friction coefficient of the test pieces produced from this molded body under the same conditions as in Examples 1 to 3.

表１の結果から明らかなように、実施例１〜３のウエット面に対する摩擦係数は、比較例１のウエット面に対する摩擦係数よりも高い値を示していることから、水で覆われた路面（低摩擦係数の路面）におけるスリップを抑制することができることがわかる。また、実施例１〜３のドライ面に対する摩擦係数は、比較例１のドライ面に対する摩擦係数と同等又は高い値を示していることから、ドライの路面においてもスリップ抑制効果が十分に発揮されることがわかる。さらに、鉄及びコンクリートのいずれにおいても、実施例１〜３の摩擦係数は、比較例１の摩擦係数よりも高まることから、実施例１〜３では路面状況の異なる場合（摩擦係数の異なる路面）でも、スリップ抑制効果が発揮されることがわかる。

As is clear from the results in Table 1, the friction coefficient with respect to the wet surfaces of Examples 1 to 3 shows a higher value than the friction coefficient with respect to the wet surface of Comparative Example 1, so that the road surface covered with water ( It can be seen that slip on a road surface having a low friction coefficient can be suppressed. Moreover, since the friction coefficient with respect to the dry surface of Examples 1-3 has shown the value equivalent to or higher than the friction coefficient with respect to the dry surface of the comparative example 1, the slip suppression effect is fully exhibited also on the dry road surface. I understand that. Furthermore, in both iron and concrete, the friction coefficient of Examples 1 to 3 is higher than the friction coefficient of Comparative Example 1, so in Examples 1 to 3 where the road surface conditions are different (road surfaces having different friction coefficients). However, it turns out that the slip suppression effect is exhibited.

  On the other hand, since the measurement result of the static physical property in each Example is equivalent to the measurement result of the static physical property in Comparative Example 1, it can be seen that the physical property inherent to the polyurethane resin is sufficiently maintained. Moreover, according to the result of the abrasion test in each example, since the value of each Example has shown the value lower than the value of Comparative Example 1, the abrasion resistance of each Example is superior to Comparative Example 1. I understand that.

(Comparative Example 2)
A polyurethane resin molded article was produced in the same manner as in Comparative Example 1 except that metal mami was embedded in the polyurethane prepolymer. About the test piece produced from this molded object, the static friction coefficient and dynamic friction coefficient with respect to the ice surface were measured like the method of Examples 1-3. Moreover, the static friction coefficient and dynamic friction coefficient with respect to the ice surface were also measured for the molded bodies in Example 1 and Comparative Example 1. These results are shown in Table 2.

表２の結果から明らかなように、実施例１の摩擦係数は、比較例１の摩擦係数よりも高い値を示している。これらの結果から、実施例１では、氷面においてもスリップ抑制効果が発揮されることがわかる。また、実施例１の摩擦係数は、比較例２の摩擦係数と同等の値を示している。これらの結果から、実施例１ではアミを埋設しなくても、比較例１と同等のスリップ抑制効果を奏するため、アミの埋設を要因とする衛生面に対する影響を防止することもできる。

As is clear from the results in Table 2, the friction coefficient of Example 1 is higher than that of Comparative Example 1. From these results, it can be seen that in Example 1, the slip suppression effect is exhibited even on the ice surface. Further, the friction coefficient of Example 1 is equivalent to the friction coefficient of Comparative Example 2. From these results, in Example 1, the slip suppression effect equivalent to that of Comparative Example 1 can be obtained without embedding the muddy, so that the influence on hygiene caused by embedding of mummy can be prevented.

(Examples 4 to 7)
As silicone oils, dimethylpolysiloxane shown in (B) in Table 3 (kinematic viscosity at 25 ° C .: 1000 mm ² / s), methyl hydrogen polysiloxane shown in (C) (kinematic viscosity at 25 ° C .: 20 mm ² / s) ), Heptadecafluorodecyltriisopropoxysilane as a modified siloxane represented by (D) [one containing an organic group at the side chain and both ends. Chemical formula: CF ₃ (CF ₂ ) ₇ CH ₂ CH ₂ Si (OCH (CH ₃ ) ₂ ) ₃ , molecular weight: 652], and fluorine-modified dimethylpolysiloxane represented by (E) (-CH _{2 in} a part of the side chain) A urethane resin molded article was produced in the same manner as in Example 1 except that CH ₂ CF ₃ was introduced and kinematic viscosity at 25 ° C .: 100 mm ² / s) was used. Table 3 shows the static physical properties of the molded bodies of Examples 4 to 7. Furthermore, test pieces were prepared from the molded bodies of Examples 4 to 7, and the static friction coefficient and the dynamic friction coefficient were measured for these test pieces using a friction measuring machine (TR type) manufactured by Toyo Seiki Seisakusho. In addition, each friction coefficient was measured with respect to iron (dry surface and wet surface). The measurement results are shown in Table 3.

表３の結果に示すように、実施例４〜７のウエット面における摩擦係数は、表１に示す比較例１のウエット面における摩擦係数よりも高い値を示していることから、水で覆われた路面（低摩擦係数の路面）におけるスリップを抑制することができることがわかる。さらに、実施例４〜７における静的物性の測定結果は、比較例１における静的物性の測定結果と同等であることから、ポリウレタン樹脂が本来有する物性は、十分に維持されていることがわかる。

As shown in the results in Table 3, the friction coefficient on the wet surfaces of Examples 4 to 7 is higher than the friction coefficient on the wet surface of Comparative Example 1 shown in Table 1, and thus is covered with water. It can be seen that slip on the road surface (road surface with a low coefficient of friction) can be suppressed. Furthermore, since the measurement result of the static physical property in Examples 4-7 is equivalent to the measurement result of the static physical property in the comparative example 1, it turns out that the physical property which a polyurethane resin originally has is fully maintained. .

Claims (4)

A polyurethane composition for molding the tread portion of a solid tire comprising a wheel and a tread portion covering the outer peripheral surface of the wheel,
Silicone oils are blended with the polyurethane prepolymer that is the base material,
The silicone oil is at least one selected from dimethylsiloxane, methylhydrogensiloxane, and modified siloxane obtained by introducing an organic group into the dimethylsiloxane. The polyurethane composition according to claim 1, wherein at least dimethylpolysiloxane is blended as the silicone oil. The polyurethane composition according to claim 1 or 2, wherein 0.1 to 10 parts by mass of the silicone oil is blended with 100 parts by mass of the polyurethane prepolymer. The solid tire which has the said tread part shape | molded by hardening | curing the polyurethane composition as described in any one of Claims 1-3.