Polyurethane resin composition, steering wheel, and method for producing polyurethane resin composition

Abstract

This polyurethane resin composition is formed by reacting an isocyanate ingredient, a polyol ingredient, and a filler. The polyol ingredient mainly includes a polyol having an ethylene oxide chain as a basic skeleton. The filler is a modified lignin obtained by modifying lignin by binding polyethylene glycol to the lignin.

Description

Polyurethane resin composition, steering wheel, and method for producing polyurethane resin composition

[0001] The present disclosure relates to a polyurethane resin composition, a steering wheel, and a method for producing a polyurethane resin composition.

[0002] Patent Document 1 discloses a steering wheel for an automobile. The steering wheel disclosed in Patent Document 1 includes a core metal having a ring portion and a polyurethane covering material that covers the ring portion. The polyurethane is formed by reacting a polyisocyanate and a polyol.

[0003] Conventionally, in polyurethane resin compositions constituting steering wheel covering materials, polypropylene glycol (PPG) has been used as the polyol because it has a suitable hardness.

[0004] Japanese Patent Application Laid-Open No. 2019-77379

[0005] In recent years, there has been a demand for adding biomass materials derived from living organisms to steering wheel covering materials in order to reduce the use of fossil fuels and, in turn, reduce emissions of carbon dioxide, a greenhouse gas.

[0006] However, it is difficult to add biomass materials to PPG. Alternatively, polyethylene glycol (PEG) could be used as a polyol component. However, this would result in a lower hardness of the coating material than when PPG is used as the polyol component, making it difficult to use as a coating material for steering wheels.

[0007] It should be noted that these problems are not limited to polyurethane resin compositions for use as steering wheel covering materials, but are also found in other polyurethane resin compositions.

[0008] A polyurethane resin composition according to one embodiment of the present disclosure is formed by reacting an isocyanate component, a polyol component, and a filler, wherein the polyol component mainly contains a polyol having an ethylene oxide chain as a basic skeleton, and the filler is modified lignin modified by bonding polyethylene glycol thereto.

[0009] A steering wheel according to a first aspect of the present disclosure comprises a core metal and a covering material made of a polyurethane resin composition and covering the core metal, the polyurethane resin composition being formed by the reaction of an isocyanate component, a polyol component, and a filler, the polyol component mainly containing a polyol having an ethylene oxide chain as a basic skeleton, the filler being a modified lignin modified by bonding with polyethylene glycol, and the molecular weight of the polyol having an ethylene oxide chain as a basic skeleton being 100 or more and 600 or less.

[0010] A steering wheel according to a second aspect of the present disclosure comprises a core metal and a covering material made of a polyurethane resin composition and covering the core metal, wherein the polyurethane resin composition is formed by reacting an isocyanate component, a polyol component, and a filler, the polyol component mainly containing a polyol having an ethylene oxide chain as a basic skeleton, the filler being a modified lignin modified by bonding with polyethylene glycol, and the mass percentage concentration of the filler in the polyurethane resin composition being 5 wt% or more and 25 wt% or less.

[0011] A method for producing a polyurethane resin composition according to one embodiment of the present disclosure includes producing the polyurethane resin composition by reacting an isocyanate component, a polyol component, and a filler, wherein the polyol component mainly contains a polyol having an ethylene oxide chain as a basic skeleton, and the filler is modified lignin modified by bonding polyethylene glycol thereto.

[0012] Fig. 1 is a table showing various data of examples of polyurethane resin compositions, Fig. 2 is a table showing various data of comparative examples of polyurethane resin compositions, and Fig. 3 is a cross-sectional view of a steering wheel.

[0013] One embodiment will now be described with reference to the drawings. As shown in Figure 3, an automobile steering wheel 10 includes a core 11 and a covering material 12 made of a polyurethane resin composition and covering the core 11.

[0014] The polyurethane resin composition of the present embodiment and its production method will be described below. The polyurethane resin composition is formed by reacting an isocyanate component, a polyol component, and a filler.

[0015] The isocyanate component is a well-known isocyanate used in the production of polyurethane. The polyol component mainly contains a polyol having an ethylene oxide chain as a basic skeleton. The molecular weight of the polyol having an ethylene oxide chain as a basic skeleton is preferably 100 or more and 600 or less.

[0016] The filler is modified lignin modified by bonding polyethylene glycol (PEG). The mass percent concentration of the filler in the polyurethane resin composition is preferably 5 wt% or more and 25 wt% or less. The mass percent concentration of the filler in the polyurethane resin composition is more preferably 8 wt% or more and 21 wt% or less.

[0017] In addition, the method for producing a polyurethane resin composition is a method for producing a polyurethane resin composition by reacting an isocyanate component, a polyol component, and a filler, in which the polyol component mainly contains a polyol having an ethylene oxide chain as a basic skeleton, and the filler is modified lignin modified by bonding PEG.

[0018] Next, examples of polyurethane resin compositions will be described with reference to Fig. 1. (First Example) The polyurethane resin composition of the first example contains, as polyol components, 12.4 wt% of PEG, which is a bifunctional polyol and has an average molecular weight of 400, 18.6 wt% of PEG, which is a bifunctional polyol and has an average molecular weight of 600, and 8.8 wt% of PEG, which is a trifunctional polyol and has an average molecular weight of 430.

[0019] The polyurethane resin composition of Example 1 contained 41.1 wt % of isocyanate and 17.0 wt % of modified lignin. The polyurethane resin composition of Example 1 was excellent in moldability for urethane molding (evaluated as ⊚).

[0020] The Asker C hardness of the polyurethane resin composition of Example 1 was 60, which was within the Asker C hardness range of 50 to 90, which is suitable for the covering material 12 (evaluated as ⊚). The polyurethane resin composition of Example 1 did not produce sink marks (evaluated as ⊚).

[0021] For these reasons, the overall evaluation of the polyurethane resin composition of Example 1 was ⊚. (Example 2) The polyurethane resin composition of Example 2 contained, as polyol components, 31.0 wt % of PEG, which is a bifunctional polyol and has an average molecular weight of 200, and 8.8 wt % of PEG, which is a trifunctional polyol and has an average molecular weight of 430.

[0022] The polyurethane resin composition of Example 2 contained 41.1 wt % of isocyanate and 17.0 wt % of modified lignin. The polyurethane resin composition of Example 2 was excellent in moldability for urethane molding (evaluated as ⊚).

[0023] The Asker C hardness of the polyurethane resin composition of Example 2 was 90, which was within the Asker C hardness range of 50 or more and 90 or less, which is suitable for the covering material 12 (evaluation: ○). The polyurethane resin composition of Example 2 did not produce sink marks (evaluation: ⊚).

[0024] For these reasons, the overall evaluation of the polyurethane resin composition of Example 2 was ⊚ to ○. In the polyurethane resin composition of Example 2, the average molecular weight of the bifunctional polyol PEG was lower than in Example 1, which is thought to have shortened the bond distance between the polyol and the isocyanate, resulting in a higher Asker C hardness, i.e., a harder composition.

[0025] (Third Example) The polyurethane resin composition of the third example contains, as polyol components, 31.0 wt % of PEG, which is a bifunctional polyol and has an average molecular weight of 400, and 8.8 wt % of PEG, which is a trifunctional polyol and has an average molecular weight of 430.

[0026] The polyurethane resin composition of Example 2 contained 41.1 wt % of isocyanate and 17.0 wt % of modified lignin. The polyurethane resin composition of Example 3 was excellent in moldability for urethane molding (evaluated as ⊚).

[0027] The Asker C hardness of the polyurethane resin composition of Example 3 was 83, which was within the Asker C hardness range of 50 to 90, which is suitable for the covering material 12 (evaluated as ⊚). The polyurethane resin composition of Example 3 did not produce any problematic sink marks (evaluated as ◯).

[0028] For these reasons, the overall evaluation of the polyurethane resin composition of Example 3 was rated as ⊚ to ○. Example 3 differs from Example 1 in that it uses a bifunctional polyol, PEG, with a single average molecular weight. This reduces the variation in polyurethane chain length, which is thought to have made the resin softer immediately after molding and before hardening compared to Example 1, making it more susceptible to sink marks.

[0029] Example 4 The polyurethane resin composition of Example 4 contains, as polyol components, 31.0 wt % of PEG, which is a bifunctional polyol and has an average molecular weight of 600, and 8.8 wt % of PEG, which is a trifunctional polyol and has an average molecular weight of 430.

[0030] The polyurethane resin composition of Example 2 contained 41.1 wt % of isocyanate and 17.0 wt % of modified lignin. The polyurethane resin composition of Example 4 was excellent in moldability for urethane molding (evaluated as ⊚).

[0031] The Asker C hardness of the polyurethane resin composition of Example 4 was 53, which was within the Asker C hardness range of 50 to 90, which is suitable for the covering material 12 (evaluated as ⊚). The polyurethane resin composition of Example 4 did not produce any problematic sink marks (evaluated as ◯).

[0032] For these reasons, the overall evaluation of the polyurethane resin composition of Example 4 was ⊚ to ○. Example 4 differs from Example 1 in that it uses a bifunctional polyol, PEG, with a single average molecular weight. This reduces the variation in polyurethane chain length, which is thought to have made the resin softer immediately after molding and before hardening compared to Example 1, making it more susceptible to sink marks.

[0033] (Fifth Example) The polyurethane resin composition of the fifth example contains, as polyol components, 13.6 wt% of PEG, which is a bifunctional polyol and has an average molecular weight of 400, 19.7 wt% of PEG, which is a bifunctional polyol and has an average molecular weight of 600, and 10.0 wt% of PEG, which is a trifunctional polyol and has an average molecular weight of 430.

[0034] The polyurethane resin composition of Example 1 contained 44.6 wt % of isocyanate and 10.0 wt % of modified lignin. The polyurethane resin composition of Example 5 was excellent in moldability for urethane molding (evaluated as ⊚).

[0035] The Asker C hardness of the polyurethane resin composition of Example 5 was 50, which was within the Asker C hardness range of 50 or more and 90 or less, which is suitable for the covering material 12 (evaluation: ⊚). The polyurethane resin composition of Example 5 suffered from sink marks (evaluation: Δ).

[0036] For these reasons, the overall evaluation of the polyurethane resin composition of Example 3 was ○. In Example 5, the blending ratio of modified lignin was lower than in Examples 1 to 4, and it is thought that sink marks occurred because the resin softened immediately after molding before hardening.

[0037] (Example 6) The polyurethane resin composition of Example 6 contains, as polyol components, 11.1 wt % of PEG, which is a bifunctional polyol and has an average molecular weight of 400, 17.2 wt % of PEG, which is a bifunctional polyol and has an average molecular weight of 600, and 7.5 wt % of PEG, which is a trifunctional polyol and has an average molecular weight of 430.

[0038] The polyurethane resin composition of Example 1 contained 37.1 wt% isocyanate and 25.0 wt% modified lignin. The polyurethane resin composition of Example 6 had slightly inferior moldability in urethane molding compared to Examples 1 to 5 (evaluation: ○).

[0039] The Asker C hardness of the polyurethane resin composition of Example 6 was 90, which was within the Asker C hardness range of 50 or more and 90 or less, which is suitable for the covering material 12 (evaluation: ◯). The polyurethane resin composition of Example 6 did not produce sink marks (evaluation: ◎).

[0040] For these reasons, the polyurethane resin composition of Example 6 was given an overall rating of ○. In Example 6, the amount of isocyanate blended was smaller than in Examples 1 to 5, but the amount of modified lignin blended was larger. This is thought to be why the polyurethane resin composition became harder.

[0041] It should be noted that none of the polyurethane resin compositions of Examples 1 to 6 contain ethylene glycol (EG) or polypropylene glycol (PPG). Next, comparative examples of polyurethane resin compositions will be described with reference to FIG.

[0042] (First Comparative Example) The polyurethane resin composition of the first comparative example contains, as polyol components, 31.0 wt % of EG, which is a bifunctional polyol and has an average molecular weight of 62, and 8.8 wt % of PEG, which is a trifunctional polyol and has an average molecular weight of 430.

[0043] The polyurethane resin composition of Comparative Example 1 contained 41.1 wt% isocyanate and 17.0 wt% modified lignin. Urethane molding was not possible in Comparative Example 1 (evaluation: ×). Therefore, there were no measurement results for the Asker C hardness of the polyurethane resin composition of Comparative Example 1 (evaluation: No).

[0044] The polyurethane resin composition of Comparative Example 1 did not produce sink marks (evaluated as ⊚). For these reasons, the polyurethane resin composition of Comparative Example 1 was overall evaluated as x. It is believed that in Comparative Example 1, the modified lignin did not dissolve in EG, making it impossible to form a urethane.

[0045] (Second Comparative Example) The polyurethane resin composition of the second comparative example contains, as polyol components, 15.6 wt % of PEG, which is a bifunctional polyol and has an average molecular weight of 400, 21.7 wt % of PEG, which is a bifunctional polyol and has an average molecular weight of 600, and 11.0 wt % of PEG, which is a trifunctional polyol and has an average molecular weight of 430.

[0046] The polyurethane resin composition of Comparative Example 2 contained 49.6 wt% isocyanate. The polyurethane resin composition of Comparative Example 2 did not contain modified lignin. The polyurethane resin composition of Comparative Example 2 exhibited slightly inferior moldability in urethane molding compared to Examples 1 to 5 (evaluation: Good).

[0047] The Asker C hardness of the polyurethane resin composition of the second comparative example was 25, which was outside the Asker C hardness range of 50 or more and 90 or less that is suitable for the covering material 12 (evaluation: Fair).

[0048] The polyurethane resin composition of Comparative Example 2 had problematic sink marks (evaluated as x). For these reasons, the polyurethane resin composition of Comparative Example 2 was overall evaluated as x.

[0049] In Comparative Example 2, the absence of modified lignin is believed to have caused the polyurethane resin composition to become too soft. (Comparative Example 3) The polyurethane resin composition of Comparative Example 3 contained, as polyol components, 16.6 wt% of PEG, a bifunctional polyol having an average molecular weight of 400, and 23.2 wt% of PEG, a bifunctional polyol having an average molecular weight of 600. The polyurethane resin composition of Comparative Example 3 did not contain PEG, a trifunctional polyol having an average molecular weight of 430.

[0050] The polyurethane resin composition of Comparative Example 1 contained 41.1 wt% isocyanate and 17.0 wt% modified lignin. The polyurethane resin composition of Comparative Example 3 had slightly inferior moldability in urethane molding compared to Examples 1 to 5 (evaluation: ○).

[0051] The Asker C hardness of the polyurethane resin composition of Comparative Example 3 was 65, which was within the Asker C hardness range of 50 to 90, which is suitable for the covering material 12 (evaluated as ⊚). The polyurethane resin composition of Comparative Example 3 suffered from problematic sink marks (evaluated as x).

[0052] For these reasons, the polyurethane resin composition of Comparative Example 3 was overall evaluated as x. In Comparative Example 3, the trifunctional polyol PEG with an average molecular weight of 430 was not contained, which is thought to have caused aggregation of PEG molecules, which are bifunctional polyols. This is thought to have caused the problematic sink marks.

[0053] (Fourth Comparative Example) The polyurethane resin composition of the fourth comparative example contains, as polyol components, 31.0 wt % of PPG, which is a bifunctional polyol and has an average molecular weight of 400, and 8.8 wt % of PEG, which is a trifunctional polyol and has an average molecular weight of 430. The polyurethane resin composition of the fourth comparative example does not contain PEG, which is a bifunctional polyol.

[0054] The polyurethane resin composition of Comparative Example 4 contained 41.1 wt% isocyanate and 17.0 wt% modified lignin. Urethane molding was not possible in Comparative Example 4 (evaluation: ×). Therefore, there were no Asker C hardness measurements or sink mark evaluation results for the polyurethane resin composition of Comparative Example 4 (evaluation: No).

[0055] The polyurethane resin compositions of Examples 1 to 6 and Comparative Examples 1 to 4 contain 1.1 wt% of a known reaction catalyst and 1.0 wt% of a known weathering agent. The PEG contained in the modified lignin contributes to the reaction that occurs when polyurethane is formed. Therefore, in the above Examples and Comparative Examples, when determining the amount of isocyanate to be added, not only the bifunctional polyol and trifunctional polyol but also the PEG contained in the modified lignin are considered to be polyols that react with isocyanate.

[0056] Next, the effects of this embodiment will be described. (1) In a polyurethane resin composition, when the polyol component mainly contains a polyol having an ethylene oxide chain as a basic skeleton, the hardness is lower than when the polyol component mainly contains a polyol having a propylene oxide chain as a basic skeleton.

[0057] According to the above configuration, the modified lignin filler is modified by bonding PEG to the lignin. Furthermore, the lignin constituting the modified lignin has high hardness due to the presence of a benzene ring. This increases the hardness of the polyurethane resin composition. This is thought to be because, when the polyurethane resin composition is formed, the OH groups of the modified lignin react to bond polyurethane chains together, limiting the degree of freedom of deformation of the polyurethane chains.

[0058] Therefore, the hardness of the polyurethane resin composition can be increased even though the polyol component mainly uses a polyol having an ethylene oxide chain as the basic skeleton. Furthermore, because the polyurethane resin composition is composed of lignin, which is a biomaterial, carbon dioxide emissions can be reduced.

[0059] (2) Since the molecular weight of the polyol having an ethylene oxide chain as a basic skeleton is 100 or more and 600 or less, it is possible to set the Asker C hardness of the polyurethane resin composition to 50 or more and 90 or less. This contributes to the production of a polyurethane resin composition having a hardness suitable for use as the covering material 12 of the steering wheel 10, for example.

[0060] (3) Since the mass percent concentration of the filler in the polyurethane resin composition is 5 wt % or more and 25 wt % or less, it is possible to set the Asker C hardness of the polyurethane resin composition to 50 or more and 90 or less. This contributes to the production of a polyurethane resin composition having a hardness suitable for use as the covering material 12 of the steering wheel 10, for example.

[0061] (5) The steering wheel 10 includes a core 11 and a covering material 12 made of a polyurethane resin composition and covering the core 11. This configuration allows the covering material 12 of the steering wheel 10 to meet the hardness requirements.

[0062] (6) A method for producing a polyurethane resin composition includes reacting an isocyanate component, a polyol component, and a filler to produce the polyurethane resin composition. In the production method, the polyol component mainly contains a polyol having an ethylene oxide chain as a basic skeleton. The filler is modified lignin modified by bonding PEG.

[0063] According to this method, it is possible to achieve the same effect as in (1). <Modifications> This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of no technical contradiction.

[0064] The polyurethane resin composition can also be used for applications other than the covering material 12 of the steering wheel 10. The mass percent concentration of the filler in the polyurethane resin composition may be less than 5 wt %. Also, the mass percent concentration of the filler in the polyurethane resin composition may be higher than 25 wt %.

[0065] The molecular weight of the polyol having an ethylene oxide chain as a basic skeleton, which is mainly contained in the polyol component, may be less than 100. The molecular weight of the polyol having an ethylene oxide chain as a basic skeleton, which is mainly contained in the polyol component, may be greater than 600.

[0066] The polyurethane resin composition and the method for producing a polyurethane resin composition according to the present disclosure do not exclude the inclusion of a polyol having a propylene oxide chain as a basic skeleton. In other words, the polyurethane resin composition and the method for producing a polyurethane resin composition may contain a polyol having a propylene oxide chain as a basic skeleton, as long as the polyurethane resin composition and the method for producing a polyurethane resin composition mainly contain a polyol having an ethylene oxide chain as a basic skeleton, and may also contain a polyol having a propylene oxide chain as a basic skeleton.

Claims

1. In a polyurethane resin composition formed by the reaction of an isocyanate component, a polyol component, and a filler, the polyol component mainly contains a polyol having an ethylene oxide chain as a basic skeleton, the filler is a modified lignin modified by bonding polyethylene glycol, a polyurethane resin composition.

2. The polyurethane resin composition according to claim 1, wherein the molecular weight of the polyol having an ethylene oxide chain as a basic skeleton is 100 or more and 600 or less.

3. The polyurethane resin composition according to claim 1 or 2, wherein the mass percentage concentration of the filler in the polyurethane resin composition is 5 wt% or more and 25 wt% or less.

4. A steering wheel comprising a core metal and a coating material made of the polyurethane resin composition according to claim 2 or 3 and covering the core metal.

5. In a method for producing a polyurethane resin composition, producing the polyurethane resin composition by reacting an isocyanate component, a polyol component, and a filler, the polyol component mainly contains a polyol having an ethylene oxide chain as a basic skeleton, the filler is a modified lignin modified by bonding polyethylene glycol, a method for producing a polyurethane resin composition.

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