Cork products and manufacturing method of the same

Abstract

To provide cork products that reduce the amount of petroleum-derived materials used compared to conventional cork products, and leads to a reduction in carbon dioxide emissions, and a manufacturing method of the same.SOLUTION: Cork products according to the present disclosure comprise cork particles and an urethane binder, and the cork particles are immobilized by the urethane binder, and the urethane binder comprises structural units derived from isocyanate and structural units derived from polyol, and at least one of the isocyanate and the polyol is derived from biomass.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a cork product and a method for producing the same. [Background technology]

[0002] Cork has various properties such as elasticity, heat insulation, waterproofness, breathability, and sound absorption, and therefore cork products obtained by fixing cork particles with adhesives or the like are used in various fields.

[0003] For example, Patent Document 1 discloses a cork stopper characterized in that an outer shell is formed from a synthetic resin material consisting of styrene-isoprene-styrene resin, the shell is filled with cork particles mixed with an adhesive and compressed to form a cork stopper, and then a thin film of polyethylene terephthalate resin is formed on the surface of the shell.

[0004] Meanwhile, from the viewpoint of reducing the environmental load, the use of biomass has been attracting attention. Patent Document 2 discloses a two-liquid type laminating adhesive that is composed of a base agent containing a biomass polyurethane resin made from biomass polyester polyol, the acid component and / or glycol component of which is a biomass component, and a curing agent containing an isocyanate compound. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2003-081297 A [Patent Document 2] JP 2020-189901 A Summary of the Invention [Problem to be solved by the invention]

[0006] As efforts to become carbon neutral are required, there is room for improvement in the fact that conventional cork products such as those described in Patent Document 1 use petroleum-derived adhesives. Furthermore, Patent Document 2 relates to a laminating adhesive. Until now, it was unclear whether the physical properties required of cork products could be obtained when biomass-derived adhesives were applied to cork products.

[0007] One aspect of the present invention aims to realize a cork product and a manufacturing method thereof that uses less petroleum-derived raw materials than conventional cork products, leading to a reduction in carbon dioxide emissions. [Means for solving the problem]

[0008] In order to solve the above problems, a cork product according to one embodiment of the present invention comprises cork particles and a urethane binder, the cork particles being fixed by the urethane binder, the urethane binder comprising structural units derived from an isocyanate and structural units derived from a polyol, and at least one of the isocyanate and the polyol being derived from biomass.

[0009] In order to solve the above problems, a method for producing a cork product according to one embodiment of the present invention includes the steps of mixing cork granules with an isocyanate and a polyol, and fixing the cork granules with a urethane binder produced by a reaction between the isocyanate and the polyol, wherein at least one of the isocyanate and the polyol is derived from biomass. Effect of the Invention

[0010] According to one aspect of the present invention, it is possible to provide a cork product and a method for producing the same that use less petroleum-derived raw materials than conventional cork products, leading to a reduction in carbon dioxide emissions. [Brief description of the drawings]

[0011] [Figure 1]FIG. 1 is a schematic diagram showing a pressed cork stopper according to one embodiment of the present invention. [Diagram 2] 1 is a schematic diagram showing a cork sheet according to one embodiment of the present invention; [Diagram 3] FIG. 1 is a schematic diagram showing a cork composite article according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] An embodiment of the present invention will be described below, but the present invention is not limited thereto. In this specification, unless otherwise specified, "A to B" representing a numerical range means "A or more and B or less."

[0013] [1. Cork products] A cork product according to one embodiment of the present invention includes cork particles and a urethane binder, the cork particles being fixed by the urethane binder, the urethane binder including structural units derived from an isocyanate and structural units derived from a polyol, and at least one of the isocyanate and the polyol being derived from biomass. A plurality of cork particles may be bonded together by the urethane binder, or a plurality of cork particles may be fixed onto another substrate by the urethane binder. The cork product may be a bonded body of a plurality of cork particles. A urethane binder may be interposed between a plurality of cork particles. The cork product may be formed by compression molding.

[0014] The cork granules are crushed cork. The cork granules may be cork granules obtained by crushing cork tissue from the bark of a cork oak tree, or may be cork granules obtained by crushing scraps generated during the production of natural cork stoppers.

[0015] In one embodiment of the present invention, cork particles of an appropriate size are used according to the application or desired characteristics of the cork product. For example, the average particle size of the cork particles is preferably 0.1 to 8 mm. When cork particles with an average particle size of 0.1 mm or more are used in a compressed cork stopper, the resistance when removing the compressed cork stopper is less likely to vary, making it easier to remove. The average particle size is more preferably 0.5 mm or more, and even more preferably 1 mm or more. When cork particles with an average particle size of 8 mm or less are used in a compressed cork stopper, voids are less likely to occur in the compressed cork stopper, improving the sealing performance. The average particle size is more preferably 5 mm or less, even more preferably 3 mm or less, and particularly preferably 2 mm or less. In this specification, the average particle size of the cork particles is the average value of the length (maximum diameter) of the longest straight line among the straight lines passing through the center of gravity of the cork particles.

[0016] Cork products include, but are not limited to, pressed cork stoppers, cork sheets, coasters, cork boards, cork mats, and functional members. The functional members have a specific shape according to the application to achieve the intended function. Examples of the functional members include heat insulating members, sound absorbing members, and insulating members.

[0017] FIG. 1 is a schematic diagram showing a pressed cork stopper according to one embodiment of the present invention. The pressed cork stopper 10 includes cork particles 1 and a urethane binder 2, and the cork particles 1 are fixed by the urethane binder 2. It can also be said that the urethane binder 2 is interposed between a plurality of cork particles 1. The urethane binder 2 includes a structural unit derived from an isocyanate and a structural unit derived from a polyol, and at least one of the isocyanate and the polyol is derived from biomass. Note that the pressed cork stopper 10 in FIG. 1 is exemplified as one in which compression during molding is performed in a direction perpendicular to the axis L, but the compression direction is not limited thereto.

[0018] Fig. 2 is a schematic diagram showing a cork sheet according to one embodiment of the present invention. Although not shown in the cork sheet 11 of Fig. 2, cork particles 1 are fixed by a urethane binder 2 in this cork sheet 11, similar to the pressed cork stopper 10 of Fig. 1.

[0019] The density of cork products is 0.25 to 0.4 g / cm 3 and preferably 0.25 to 0.35 g / cm 3 In particular, when the density of the compressed cork is in this range, a good balance between sealing property and ease of uncorking is achieved.

[0020] The cork product also includes a cork composite product in which cork particles are fixed on a substrate by a urethane binder. FIG. 3 is a schematic diagram showing a cork composite product according to one embodiment of the present invention. The cork composite product 20 includes a substrate 3 and a cork layer 12 fixed on the substrate 3 via a urethane binder 2. The cork layer 12 may have a structure in which the urethane binder 2 is interposed between a plurality of cork particles 1. Examples of the substrate include a wood board, a plastic board, a glass board, and a metal board. In the cork composite product 20, the cork layer 12 may have the above-mentioned density.

[0021] In this specification, the term "urethane binder" refers to a binder having urethane bonds formed by the reaction of isocyanate and polyol. The isocyanate also reacts with moisture and / or the hydroxyl groups of the cork particles to form urethane bonds. As the reaction to form urethane bonds continues, a network-like crosslinked structure is formed, and a cured product is obtained.

[0022] At least one of the isocyanate and the polyol is derived from biomass. In this specification, "derived from biomass" means that a component produced using biomass as a raw material is included. Hereinafter, the urethane binder is also referred to as a biomass-derived urethane binder. The urethane binder can reduce carbon dioxide emissions in the manufacturing process compared to a urethane binder containing a component produced using petroleum as a raw material as a main component, and can contribute to reducing environmental load. Hereinafter, a component produced using biomass as a raw material is also referred to as a biomass-derived component, and a component produced using petroleum as a raw material is also referred to as a petroleum-derived component. The biomass-derived component is obtained, for example, from a plant.

[0023] The biomass-derived urethane binder contains at least a biomass-derived component, and may consist of only a biomass-derived component, or may contain both a biomass-derived component and a petroleum-derived component. The content of the biomass-derived component in 100% by weight of the urethane binder is preferably 50 to 100% by weight, more preferably 70 to 100% by weight, and even more preferably 90 to 100% by weight.

[0024] Either the isocyanate or the polyol used to obtain the urethane binder may be derived from biomass, and preferably both the isocyanate and the polyol are derived from biomass. That is, in the urethane binder, either the structural unit derived from the isocyanate or the structural unit derived from the polyol may be derived from biomass, and preferably both the structural unit derived from the isocyanate and the structural unit derived from the polyol are derived from biomass.

[0025] Biomass-derived isocyanate means an isocyanate containing a biomass-derived component. Biomass-derived polyol means a polyol containing a biomass-derived component. All of the raw materials used in the production of the isocyanate may be biomass-derived components, or may contain both a biomass-derived component and a petroleum-derived component. Similarly, all of the raw materials used in the production of the polyol may be biomass-derived components, or may contain both a biomass-derived component and a petroleum-derived component.

[0026] The urethane binder is a binder obtained by the reaction of an isocyanate and a polyol, and therefore, since the isocyanate and the polyol can be appropriately combined according to the desired physical properties, it is easy to adjust the physical properties of the obtained cork product.

[0027] Examples of isocyanates include aliphatic isocyanates, aromatic isocyanates, and polyisocyanates thereof. The aliphatic isocyanates may be linear, branched, or cyclic. As biomass-derived isocyanates, linear aliphatic isocyanates are easily available. Examples of linear aliphatic isocyanates include tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, octamethylene diisocyanate, and decamethylene diisocyanate. From the viewpoint of easily adjusting the viscosity of the urethane binder before curing and the hardness of the urethane binder after curing to a range suitable for cork products, pentamethylene diisocyanate or hexamethylene diisocyanate, or polyisocyanates thereof are preferred. Examples of polyisocyanates include isocyanurate type, adduct type, and biuret type, with isocyanurate type being preferred.

[0028] Examples of polyols include polyether polyols, polyester polyols, and polyester polyether polyols. Polyols with a high content of biomass-derived components include polyester polyols and polyester polyether polyols, which are easily available. Examples of polyester polyols include a reaction product of a dibasic acid and a glycol, or castor oil or a derivative thereof. Polyester polyether polyols can be obtained by introducing a polyether block into polyester polyols.

[0029] Examples of dibasic acids include succinic acid, adipic acid, sebacic acid, phthalic acid, dimer acid, etc. Examples of glycols include ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, etc.

[0030] The amount of the urethane binder is preferably 1 to 40 parts by mass per 100 parts by mass of cork particles. If the amount of the urethane binder is 1 part by mass or more, sufficient mechanical properties are obtained in the cork product, and in particular sufficient sealing properties are obtained in the pressed cork stopper. The amount of the urethane binder is more preferably 2 parts by mass or more, even more preferably 3 parts by mass or more, and particularly preferably 5 parts by mass or more. If the amount of the urethane binder is 40 parts by mass or less, the pressed cork stopper is not too hard, and the pressed cork stopper is easy to pull out. The amount of the urethane binder is more preferably 30 parts by mass or less, even more preferably 25 parts by mass or less, and particularly preferably 20 parts by mass or less.

[0031] The cork product may contain additives as long as the effect according to one embodiment of the present invention is not impaired. Examples of additives include flame retardants, surfactants, thickeners, moisturizers, dye deepening agents, preservatives, antifungal agents, degassing agents, defoamers, and reduction inhibitors. The amount of additives is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 1 part by mass or less, per 100 parts by mass of cork particles.

[0032] 2. Manufacturing method of cork products The method for producing a cork product according to one embodiment of the present invention includes the steps of mixing cork granules with an isocyanate and a polyol, and fixing the cork granules with a urethane binder produced by a reaction between the isocyanate and the polyol, where at least one of the isocyanate and the polyol is derived from biomass. The matters already explained in [1. Cork products] will not be explained below.

[0033] From the viewpoints of ease of mixing with cork particles and hardness after curing, the viscosity of the isocyanate before curing at 25°C is preferably 700 to 3000 mPa·s. The viscosity is more preferably 1000 mPa·s or more, and even more preferably 1200 mPa·s or more. On the other hand, the viscosity is more preferably 2800 mPa·s or less, and even more preferably 2400 mPa·s or less. The viscosity can be determined by measuring the change in viscosity over time at 25°C using a B-type rotational viscometer in accordance with JIS Z8803.

[0034] The viscosity of the polyol before curing at 25°C is, for example, preferably 400 to 2000 mPa s, and more preferably 400 to 1500 mPa s. Within this range, it is easy to obtain physical properties equivalent to those of cork products using a petroleum-derived urethane binder.

[0035] When an isocyanate and a polyol are used, the equivalent ratio of an isocyanate group to a hydroxyl group is preferably 1.0:0.5 to 1.0:1.5, and more preferably 1.0:0.9 to 1.0:1.2.

[0036] Water may be mixed with the cork particles, isocyanate, and polyol. By mixing water, the curing reaction of the urethane binder can be promoted. The amount of water mixed with 100 parts by mass of cork particles is preferably 1 to 40 parts by mass. If the amount of water mixed is 1 part by mass or more, the urethane binder can react stably and be cured sufficiently. The amount of water is more preferably 2 parts by mass or more, even more preferably 3 parts by mass or more, and particularly preferably 5 parts by mass or more. If the amount of water mixed is 40 parts by mass or less, especially when producing a compressed cork stopper, voids are unlikely to occur in the compressed cork stopper, and the sealing property can be improved. The amount of water is more preferably 30 parts by mass or less, even more preferably 25 parts by mass or less, and particularly preferably 20 parts by mass or less.

[0037] The cork particles can be fixed by hardening the urethane binder. In the above-mentioned manufacturing method, the cork particles may be fixed with the urethane binder and molded at the same time. Alternatively, a mixture of the cork particles and the urethane binder may be molded to obtain an intermediate body, and the intermediate body may be heated to harden the urethane binder.

[0038] Examples of the molding method include compression molding and extrusion molding. When producing a cork stopper, it is preferable to compression mold a mixture of cork particles and a urethane binder. A compression molding mold having a cavity may be used for the compression molding. Specifically, the mixture can be loaded into the cavity of the compression molding mold and then compression molded.

[0039] The shape of the intermediate is not particularly limited and can be determined according to the shape of the cork product. In particular, when producing a compressed cork stopper, the intermediate is preferably approximately cylindrical. A method for obtaining such an approximately cylindrical intermediate is preferably a method for compression molding the mixture while compressing it in a direction perpendicular to the rotation axis of the cylinder. By compression molding the mixture using such a method, the plug-removing property and the plug-tightness can be further improved. Examples of a method for producing such an intermediate include the method described in JP 2010-99909 A.

[0040] By heating the obtained intermediate, the urethane binder reacts with water (water mixed with the cork particles and the urethane binder, or water in the air, etc.) to harden the urethane binder. When the urethane binder contains an isocyanate and a polyol, a reaction also occurs between the isocyanate and the polyol. The heating temperature at this time is usually 50 to 180°C. If the heating temperature is 50°C or higher, the urethane binder is easily hardened. The heating temperature is preferably 80°C or higher, and more preferably 100°C or higher. Also, if the heating temperature is 180°C or lower, the cork product can be prevented from becoming too hard. The heating temperature is preferably 170°C or lower, and more preferably 160°C or lower.

[0041] The heating time of the intermediate is usually 20 to 120 minutes. If the heating time is 20 minutes or more, the urethane binder is easily cured. The heating time is preferably 30 minutes or more. Also, if the heating time is 120 minutes or less, the cork product can be prevented from becoming too hard. The heating time is preferably 100 minutes or less, and more preferably 80 minutes or less.

[0042] Alternatively, a cork block may be obtained by compression molding, and then the cork block may be thinly sliced ​​to obtain a cork sheet. Such a cork sheet may be attached to a substrate using a urethane binder to obtain a cork composite. Alternatively, the cork sheet may be integrally molded with a resin substrate by insert molding to obtain a cork composite.

[0043] [3. Summary] An embodiment of the present invention may include the following features. <1> A cork product comprising cork particles and a urethane binder, the cork particles being fixed by the urethane binder, the urethane binder comprising structural units derived from an isocyanate and structural units derived from a polyol, and at least one of the isocyanate and the polyol being derived from biomass. <2> It is a pressed cork stopper, <2> 2. A cork product according to claim 1 . <3> It is a cork sheet, <2> 2. A cork product according to claim 1 . <4> A method for producing a cork product, comprising the steps of: mixing cork granules with an isocyanate and a polyol; and fixing the cork granules with a urethane binder produced by a reaction between the isocyanate and the polyol, wherein at least one of the isocyanate and the polyol is derived from biomass.

[0044] The cork products and their manufacturing methods are expected to contribute to reducing carbon dioxide emissions and, for example, to the achievement of Goal 13 of the Sustainable Development Goals (SDGs) advocated by the United Nations, which is to take urgent action to combat climate change.

[0045] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. EXAMPLES

[0046] An embodiment of the present invention will now be described.

[0047] [How to make a cork sheet] 100 parts by weight of cork particles, 15 parts by weight of urethane binder, and 10 parts by weight of water were mixed and compressed to obtain a cork molded body (block). The cork molded body was left to stand in an electric resistance oven at 130°C for 30 minutes. The obtained cured product was sliced ​​to obtain a cork sheet with a thickness of 2 mm.

[0048] [Block formability evaluation] During compression molding, block moldability was evaluated according to the following criteria. Good: No problems occurred, such as the binder not hardening or the binder bleeding out. Defective: The binder did not harden or there was some problem such as the binder bleeding out.

[0049] [Sheet workability evaluation] When slicing the cork molding, the sheet processability was evaluated according to the following criteria. Excellent: None of the resulting sheets had any holes or cracks. Good: Less than 5% of the total number of sheets obtained had holes or cracks. Poor: Holes or cracks occurred in 10% or more of the total number of sheets obtained.

[0050] [Heat resistance evaluation] The obtained cork sheets were placed in an oven at 100°C for 1 hour to carry out a heat resistance test. The appearance of the cork sheets after the test was visually checked against that before the test, and the degree of color change of the cork sheets was evaluated according to the following criteria. The degree of color change was measured by visually comparing each cork sheet with a gray scale of 1 to 5. Excellent: Grayscale grade 4 or above. Good: Grayscale grade 2.5 to 3.5. Poor: Grayscale level 2 or below.

[0051] [How to make a cork stopper] 100 parts by mass of cork particles, 15 parts by mass of urethane binder, and 10 parts by mass of water were mixed. The mixture obtained was compression molded using a molding device described in JP 2010-99909 A. A cylindrical intermediate body having a diameter of 25.5 mm and a length of 40 mm was obtained by the compression molding. The obtained intermediate body was loaded into a cylindrical container, which is a heating mold, having a cavity with the same dimensions as the intermediate body. The cylindrical container was then left to stand in an electric resistance oven at 130°C for 15 minutes. The obtained cured product was polished to obtain a diameter of 23.5 mm, a length of 38 mm, and a density of 0.27 g / cm. 3 Thus, cylindrical pressed cork stoppers were obtained.

[0052] [Cork stopper moldability evaluation] The cork stopper moldability during compression molding was evaluated according to the following criteria. Excellent: The material was able to be compressed and molded without any binder seeping out. Good: No binder seeped through, but more pressure was required than for "Excellent." Poor: Binder bled or more pressure was required than for "Good".

[0053] [Cork sealability evaluation] A wine bottle (inner diameter 19 mm) was filled with wine and then sealed with the obtained pressed cork. The wine bottle was placed on its side, with the wine and the pressed cork in contact, and left to stand for 6 days while gradually increasing the temperature (maximum temperature 40°C). After leaving it to stand for 1 day at room temperature, the cork was visually observed and the wine permeability was evaluated according to the following criteria. The presence or absence of leakage was also confirmed based on the weight of the bottle before and after leaving it to stand. Good: The cork was not soaked with wine and there was no leakage. Poor: The cork was soaked with wine and / or leaking.

[0054] [Evaluation Results] Table 1 shows the compositions and evaluation results of Examples 1 and 2 and Comparative Examples 1 to 3.

[0055] [Table 1]

[0056] The binders shown in the table are as follows: Example 1: Trade name URIC H-420 (main component: castor oil-based polyester polyether polyol) manufactured by Ito Oil Mills and trade name STABIO D370N (main component: polyisocyanate of pentamethylene diisocyanate (PDI)) manufactured by Mitsui Chemicals Example 2: URIC H-30 (main component: castor oil), manufactured by Ito Oil Mills, and STABIO D370N (main component: polyisocyanate of pentamethylene diisocyanate (PDI)), manufactured by Mitsui Chemicals Comparative Example 1: Asahi Kasei Corporation, product name Duranate TSE-100 (main component: polyisocyanate of hexamethylene diisocyanate (HDI)) Comparative Example 2: Product name TE-232 (epoxy binder) manufactured by Oshika Co., Ltd. Comparative Example 3: Mitsui Chemicals, product name STABIO D370N (main component: polyisocyanate of pentamethylene diisocyanate (PDI)) In Examples 1 and 2, polyol and isocyanate were mixed so that the equivalent ratio of isocyanate groups to hydroxyl groups was 1.0:1.0, and then mixed with cork particles.

[0057] Additionally, the viscosity of the binder is a value disclosed by each manufacturer. The biomass material ratio was also calculated based on the value disclosed by each manufacturer. The biomass material ratio (total) represents the weight ratio of biomass-derived materials to all materials contained in the cork product, and is a value calculated including cork granules as a biomass material. The biomass material ratio (binder) represents the weight ratio of biomass-derived materials to all binders, and does not include cork granules in the calculation.

[0058] As shown in Table 1, it was found that Examples 1 and 2, which used a biomass-derived urethane binder, were able to achieve physical properties comparable to those of Comparative Examples 1 and 2, which used a petroleum-derived urethane binder. Moreover, Example 1 had superior cork stopper moldability compared to Comparative Example 3, which had the same biomass material ratio but used only isocyanate. [Industrial Applicability]

[0059] One aspect of the present invention can be utilized in cork products. [Explanation of symbols]

[0060] 1 cork grain 2. Urethane binder 3 Base material 10 Pressed cork 11 Cork Sheet 12 Cork layer 20 Cork composite products

Claims

1. Contains cork particles and a urethane binder, The cork particles are fixed by the urethane binder, the urethane binder comprises an isocyanate-derived structural unit and a polyol-derived structural unit, 1. A cork product, wherein at least one of the isocyanate and the polyol is derived from biomass.

2. 10. The cork product of claim 1 which is a pressed cork stopper.

3. 10. The cork product of claim 1 which is a cork sheet.

4. mixing cork granules, isocyanate and polyol; and fixing the cork particles with a urethane binder produced by the reaction of the isocyanate and the polyol.

13. A method for producing a cork product, wherein at least one of the isocyanate and the polyol is derived from biomass.

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