Coffee residue clay as well as preparation method and application thereof

Abstract

The invention discloses coffee residue clay as well as a preparation method and application thereof, and belongs to the technical field of coffee residue recycling. The preparation method of the clay comprises the following steps: mixing 50 parts of coffee grounds with 2.5-4 parts of xanthan gum and 16-20 parts of sodium carboxymethyl cellulose to obtain solid powder; fully mixing the solid powder with 100 parts of a preservative aqueous solution to obtain a moldable product; and compacting and molding the moldable product in a mold, and then demolding and drying. According to the method, the coffee grounds are used as main components and are wide in source, the coffee grounds can be recycled, waste is turned into wealth, and the production cost of the clay is greatly reduced. Besides, the coffee residue clay is simple in raw material composition, environment-friendly, safe, non-toxic and harmless, the preparation process is easy to operate, and the prepared coffee residue clay is high in plasticity, has playability and interestingness, and can be further polished and colored to prepare decorations which can be stored for a long time and have practical and decorative values.

Description

Technical Field

[0001] The present invention relates to the technical field of coffee grounds recycling, and in particular, to a coffee grounds clay, a preparation method thereof, and an application thereof. Background Art

[0002] Coffee is the second most consumed beverage globally after tea. During the coffee preparation process, waste coffee grounds (SCGs) are generated. Current research results show that only 18wt% - 22wt% of the solubles are extracted for drinking during coffee preparation, and the remaining 78wt% - 82wt% are waste coffee grounds (SCGs). Waste coffee grounds (SCGs) belong to kitchen waste. For the treatment of such kitchen waste, most current methods involve landfilling. However, applying untreated waste coffee grounds to the soil can have certain negative impacts on agriculture and the environment.

[0003] In view of this, the present invention is specifically proposed. Summary of the Invention

[0004] The purpose of the present invention is to provide a coffee grounds clay, a preparation method thereof, and an application thereof to solve or improve the above technical problems.

[0005] The present invention can be implemented as follows:

[0006] In a first aspect, the present invention provides a preparation method of a coffee grounds clay, which includes the following steps: By mass, 50 parts of coffee grounds material are mixed with 2.5 parts - 4 parts of xanthan gum and 16 parts - 20 parts of sodium carboxymethylcellulose to obtain a solid powder; the solid powder is mixed with 100 parts of an aqueous preservative solution to obtain a plastic product; the plastic product is compacted and formed in a mold, and then demolded and dried.

[0007] In an optional embodiment, the water content of the coffee grounds material is not higher than 5wt%.

[0008] In an optional embodiment, the coffee grounds material is obtained by drying waste coffee grounds at 40°C - 50°C for 45h - 50h.

[0009] In an optional embodiment, the mass percentage of the preservative in the aqueous preservative solution is 0.1% - 0.3%.

[0010] In an optional embodiment, the preservative includes potassium sorbate.

[0011] In an optional embodiment, the aqueous preservative solution is added to the solid powder and mixed at least in two portions.

[0012] In an optional embodiment, the compaction and forming are carried out under a pressure of not less than 30N.

[0013] In a second aspect, the present invention provides a coffee residue clay, which is prepared by the preparation method according to any one of the foregoing embodiments.

[0014] In an alternative embodiment, the volume shrinkage rate of the coffee residue clay is 44% to 48%.

[0015] In a third aspect, the present invention provides an ornament, and the raw materials for its preparation include the coffee residue clay according to the foregoing embodiments.

[0016] The beneficial effects of the present invention include:

[0017] In the preparation method of the coffee residue clay provided by the present invention, the coffee residue material is used as the main component of the raw materials for preparing the clay. Its source is extensive, and it can realize the recycling of the coffee residue material, turning waste into treasure. At the same time, it can also greatly reduce the production cost of the clay. In addition, the raw materials of the coffee residue clay are simple, environmentally friendly, safe, non-toxic and harmless. The preparation process is easy to operate. The obtained coffee residue clay has strong plasticity, playability and interestingness. Moreover, it can be further prepared into ornaments with long-term preservation and both practical value and decorative value through post-treatment such as polishing and coloring. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0019] Figure 1 It is a physical picture of the plastic product prepared in Example 1 of the present invention;

[0020] Figure 2 It is a physical picture of a part of the coffee residue clay after being formed in Example 1;

[0021] Figure 3 It is a physical picture of some ornaments further obtained from the coffee residue clay prepared in Example 1;

[0022] Figure 4 It is a result picture after the drop resistance test of the coffee residue clay prepared in Example 1 and Comparative Example 3;

[0023] Figure 5 It is an operation picture of the impact resistance test of the coffee residue clay prepared in Example 1 and Comparative Example 2;

[0024] Figure 6 It is a result picture after the impact resistance test of the coffee residue clay prepared in Example 1 and Comparative Example 2. Detailed Implementation Modes

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described clearly and completely below. For those not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase.

[0026] The coffee residue clay provided by the present invention, its preparation method, and applications will be specifically described below.

[0027] The inventors proposed that the components of existing clay toys are relatively complex, and most of them contain industrial raw materials. If children accidentally ingest them, there are certain potential safety hazards to the physical health of children; in addition, the preparation process of existing clay toys is relatively complex, and a large amount of energy, such as electric energy, is consumed in the raw material treatment. Considering the defects that the current application of waste coffee residues in the soil will have certain negative impacts on agriculture and the environment, etc., the inventors creatively proposed a method for preparing clay using coffee residues. This method is relatively simple both in terms of raw material use and operation method. While realizing the transformation of waste coffee residues into valuable resources, it can also improve the safety during the use of clay to a certain extent.

[0028] In the present invention, the preparation method of coffee residue clay includes the following steps: by mass, 50 parts of coffee residue material are mixed with 2.5 parts to 4 parts of xanthan gum and 16 parts to 20 parts of sodium carboxymethylcellulose to obtain a solid powder; the solid powder is fully mixed with 100 parts of an aqueous preservative solution to obtain a plasticizable product; the plasticizable product is compacted and formed in a mold, and then demolded and dried.

[0029] In some alternative embodiments, the water content of the coffee residue material is not higher than 5 wt%, such as 5 wt%, 4 wt%, 3 wt%, 2 wt%, 1 wt%, or 0.5 wt%, etc., and can also be other values within the range not higher than 5 wt%. Exemplarily, the above coffee residue material can be obtained by drying waste coffee residues at 40°C to 50°C (such as 40°C, 45°C, or 50°C, etc.) for 45 h to 50 h (such as 45 h, 48 h, or 50 h, etc.). Among them, the waste coffee residues can be directly collected from coffee shops as fresh waste coffee residues. In addition, the waste coffee residues can also be obtained from other channels through other means.

[0030] Among them, waste coffee grounds (SCGs) are natural materials mainly composed of cellulose, hemicellulose, and lignin, and have the potential to produce bio-based materials. In existing materials with secondary utilization of waste coffee grounds, the content of waste coffee grounds is relatively low (less than 50%). However, the method provided in this application for preparing clay from waste coffee grounds greatly increases the treatment volume of waste coffee grounds.

[0031] In some alternative embodiments, the amount of xanthan gum used per 50 parts of coffee residue can be 2.5 parts, 3 parts, 4 parts, 4.5 parts, etc., or other values within the range of 2.5 parts to 4 parts.

[0032] If the amount of xanthan gum is less than 2.5 parts, it is not conducive to the fluidity of the clay material; if the amount of xanthan gum is higher than 4 parts, it is easy to agglomerate, which is not conducive to the mixing of solid powder and the preservative aqueous solution.

[0033] The amount of sodium carboxymethylcellulose used per 50 parts of coffee residue can be 16 parts, 16.5 parts, 17 parts, 17.5 parts, 18 parts, 18.5 parts, 19 parts, 19.5 parts, or 20 parts, etc., or other values within the range of 16 parts to 20 parts.

[0034] If the amount of sodium carboxymethylcellulose is less than 16 parts, it is not conducive to the adhesion of coffee residue into clay; if the amount of xanthan gum is higher than 20 parts, the water absorption is too strong, which is not conducive to the mixing of solid powder and the preservative aqueous solution.

[0035] Both the above-mentioned xanthan gum and sodium carboxymethylcellulose play the role of "natural glue". Among them, sodium carboxymethylcellulose is a biodegradable water-soluble polymer derived from cellulose. Adding sodium carboxymethylcellulose can increase the viscosity of the material and can be used as an adhesive for waste coffee residue. Xanthan gum is a biodegradable water-soluble natural polysaccharide, which can prevent waste coffee residue from separating from the plasticizable product, and at the same time can increase the static viscosity of the plasticizable product and enhance its shear thinning property.

[0036] Continuing from the above, by specifically setting the amounts of coffee residue, xanthan gum, and sodium carboxymethylcellulose in this application to 50:(2.5 - 4):(16 - 20), it can achieve effective mixing among the raw materials for preparing coffee residue clay on the basis of ensuring the maximum amount of coffee residue, provide appropriate viscosity and plasticity for the clay, and at the same time maximize the reduction of production costs, effectively solve the problem of waste coffee residue treatment. The obtained coffee residue clay can replace traditional plastic clay to a certain extent, realizing "resource recycling and reuse", reducing the pollution caused by plastic products to a certain extent, and having the potential for economic value addition.

[0037] In the present invention, 100 parts of the preservative aqueous solution are used per 50 parts of coffee residue. Among them, the mass percentage of the preservative in the preservative aqueous solution can be 0.1% - 0.3%, such as 0.1%, 0.15%, 0.2%, 0.25%, or 0.3%, etc., or other values within the range of 0.1% - 0.3%.

[0038] It should be noted that if the ratio of the solid powder to the preservative aqueous solution is lower than 1:2 (such as 0.5:2), the mixture of the two is likely to be too thin and the plasticity is not strong; similarly, if the ratio of the solid powder to the preservative aqueous solution is higher than 1:2 (such as 1.5:2), the mixture of the two is likely to be too dry and the plasticity is not strong. By setting the mass percentage of the preservative in the preservative aqueous solution to 0.1% to 0.3%, the clay can have a long-term antiseptic effect while minimizing the amount of preservative.

[0039] By way of example, the preservative used in the present invention may include, by way of example but not limitation, potassium sorbate. In addition, other non-toxic and harmless preservative substances may also be used.

[0040] In some optional embodiments, the aqueous preservative solution can be added to the solid powder and mixed at one time; in other optional embodiments, the aqueous preservative solution is added to the solid powder and mixed at least twice. This method can improve the mixing uniformity of the solid powder and the aqueous preservative solution compared to adding it all at once, which is beneficial to improving the performance of the coffee grounds clay (such as volume shrinkage, drop resistance, impact resistance, collapse resistance, etc.).

[0041] In some optional embodiments, the compaction molding can be performed under a pressure of not less than 30 N. In some typical embodiments, the compaction molding is performed under a pressure of 30 N to 50 N (such as 30 N, 35 N, 40 N, 45 N or 50 N, etc.). Compaction molding under the above pressure range is more conducive to making the coffee grounds clay have better volume shrinkage, drop resistance, impact resistance and collapse resistance.

[0042] In some optional embodiments, demoulding and drying may be carried out by natural air drying after demoulding.

[0043] Correspondingly, the present invention also provides coffee grounds clay, which is prepared by the above preparation method.

[0044] In some optional embodiments, the volume shrinkage of coffee grounds clay may be 44% to 48%.

[0045] As mentioned above, the present invention successfully realizes the preparation of coffee grounds clay with coffee grounds as the main component. The obtained coffee grounds clay is environmentally friendly and hygienic, non-toxic and harmless, has good plasticity, can be processed repeatedly, and can depict details in detail.

[0046] Furthermore, the present invention also provides a decorative item, the raw materials for preparing the decorative item include the coffee grounds clay mentioned above.

[0047] In some embodiments, the decorations can be obtained by further polishing, coloring, and other post-processing of coffee grounds clay.

[0048] As an example, the ornament can be a display piece or a hanging piece, etc., which can have both practical value and decorative value.

[0049] The features and performance of the present invention will be further described in detail below in conjunction with the embodiments.

[0050] Embodiment 1

[0051] This embodiment provides a coffee grounds clay (as Figure 2 shown), and its preparation method is as follows:

[0052] S1: Collect fresh waste coffee grounds, dry them at 45 °C for 48 h to obtain coffee grounds material with a water content not exceeding 5 wt%.

[0053] S2: By mass, mix 50 parts of the coffee grounds material with 2.5 parts of xanthan gum and 16 parts of sodium carboxymethylcellulose to obtain a solid powder.

[0054] S3: Add 100 parts of the preservative aqueous solution to the solid powder in multiple batches (three batches) and mix to obtain a plasticizable product (as Figure 1 shown). Among them, the preservative aqueous solution is a potassium sorbate aqueous solution with a mass concentration of 0.2%.

[0055] S4: Compact and mold the plasticizable product in a mold, and then demold and dry it. Among them, the pressure for compaction and molding is 40 N.

[0056] The above-mentioned coffee grounds clay obtained by compaction and molding can be further polished, colored, etc. to obtain an ornament (as Figure 3 shown).

[0057] Embodiment 2

[0058] The difference between this embodiment and Embodiment 1 is that the solid powder is obtained by mixing 50 parts of the coffee grounds material with 4 parts of xanthan gum and 20 parts of sodium carboxymethylcellulose.

[0059] Embodiment 3

[0060] The difference between this embodiment and Embodiment 1 is that the solid powder is obtained by mixing 50 parts of the coffee grounds material with 4 parts of xanthan gum and 16 parts of sodium carboxymethylcellulose.

[0061] Embodiment 4

[0062] The difference between this embodiment and Embodiment 1 is that the solid powder is obtained by mixing 50 parts of the coffee grounds material with 2.5 parts of xanthan gum and 20 parts of sodium carboxymethylcellulose.

[0063] Embodiment 5

[0064] The difference between this embodiment and Embodiment 1 lies in that the solid powder is obtained by mixing 50 parts of coffee residue, 3 parts of xanthan gum, and 18 parts of sodium carboxymethyl cellulose.

[0065] Embodiment 6

[0066] The difference between this embodiment and Embodiment 1 lies in that the aqueous solution of the preservative is added to the solid powder at one time and mixed.

[0067] Embodiment 7

[0068] The difference between this embodiment and Embodiment 1 lies in that the pressure for compaction molding is 30 N.

[0069] Comparative Example 1

[0070] The difference between this comparative example and Embodiment 1 lies in that the solid powder is obtained by mixing 50 parts of coffee residue, 2 parts of xanthan gum, and 16.5 parts of sodium carboxymethyl cellulose.

[0071] Comparative Example 2

[0072] The difference between this comparative example and Embodiment 1 lies in that the solid powder is obtained by mixing 50 parts of coffee residue, 4.5 parts of xanthan gum, and 14 parts of sodium carboxymethyl cellulose.

[0073] Comparative Example 3

[0074] The difference between this comparative example and Embodiment 1 lies in that the solid powder is obtained by mixing 50 parts of coffee residue, 2.5 parts of xanthan gum, and 22 parts of sodium carboxymethyl cellulose.

[0075] Comparative Example 4

[0076] The difference between this comparative example and Embodiment 1 lies in that the solid powder is obtained by mixing 50 parts of coffee residue, 5 parts of xanthan gum, and 22 parts of sodium carboxymethyl cellulose.

[0077] Comparative Example 5

[0078] The difference between this comparative example and Embodiment 1 lies in that xanthan gum is replaced with an equal amount of gelatin.

[0079] Comparative Example 6

[0080] The difference between this comparative example and Embodiment 1 lies in that sodium carboxymethyl cellulose is replaced with an equal amount of β-cyclodextrin.

[0081] Comparative Example 7

[0082] The difference between this comparative example and Embodiment 1 lies in that the dosage ratio of the solid powder to the aqueous solution of the preservative is 0.5:2.

[0083] Comparative Example 8

[0084] The difference between this comparative example and Example 1 lies in that the dosage ratio of the solid powder to the aqueous preservative solution is 2.5:2.

[0085] Comparative Example 9

[0086] The difference between this comparative example and Example 1 lies in that the pressure for compaction molding is 25 N.

[0087] Test Example

[0088] The coffee residue clays prepared in Examples 1 to 7 and Comparative Examples 1 to 9 were respectively subjected to the following performance tests. The performance tests were all carried out at room temperature of 25 °C. The anti-drop performance and collapse performance both referred to the test method of ultra-light clay. The results are shown in Table 1 and Figure 4 、 Figure 6 as shown.

[0089] (1) Shrinkage rate: It refers to the volume shrinkage rate, and its test method is as follows: During the preparation of the coffee residue clay, 105 g of the plasticizable product was loaded into a mold and subjected to compaction molding (the compaction pressure can be carried out according to the set values of each example and comparative example). The clay sample was demolded, and its dimensions were measured with a vernier caliper. After the prepared clay specimen was naturally air-dried and cured, its dimensions were measured with a vernier caliper, and the measurement results were recorded. The shape of the mold was cylindrical, and the wet-base diameter, wet-base height, dry-base diameter, and dry-base height needed to be recorded. The calculation was carried out according to the following formula:

[0090] (2) Anti-drop performance: Take 105 g of the clay sample and press it into a disc shape with a thickness of 2 cm. Place it in a completely dry state and make a free-fall motion and other projectile motions from a height of 1 m. After landing on the ground, if the sample has no obvious cracking or deformation, it meets the standard.

[0091] (3) Impact resistance: Take 105 g of the clay sample and press it into a disc shape with a thickness of 2 cm. Place it in a completely dry state and drill holes in the cured sample with an electric drill with a rotational speed of 50,000 revolutions per minute (such as Figure 5 ), and if the sample has no obvious cracking, it meets the standard.

[0092] (4) Collapse performance: Take 65 g of the clay sample and knead it into a sphere with a diameter of 5 cm. Naturally place it on a smooth horizontal plane for 20 min, and then measure the plane diameter at the contact between the sample and the smooth horizontal plane with a vernier caliper. If the diameter < 1 cm, it meets the standard.

[0093] Table 1 Performance test results of coffee residue clay

[0094]

[0095]

[0096] As shown in Table 1, the coffee grounds clay prepared in Examples 1 to 5 and Example 7 has a soft texture and strong plasticity. The comprehensive effect of Example 6 is significantly worse than that of Example 1, indicating that the preservative aqueous solution and the solid powder can be mixed in batches to improve the comprehensive performance of the clay product rather than mixing them all at once.

[0097] It can be seen from Example 1 and Comparative Examples 1 to 4 that even if the solid powder contains coffee grounds, xanthan gum and sodium carboxymethyl cellulose, if the three are not properly compounded, the comprehensive performance of the clay product will be reduced.

[0098] It can be seen from Example 1 and Comparative Examples 5 to 6 that when the commonly used thickener gelatin or β-cyclodextrin is used instead of the xanthan gum or sodium carboxymethyl cellulose in the present application, the comprehensive performance of the obtained clay is not as good as that of the solution of compounding xanthan gum and sodium carboxymethyl cellulose, indicating that compounding coffee grounds with any substance having a thickening effect cannot achieve the effect of the present application.

[0099] It can be seen from Example 1 and Comparative Examples 7 to 8 that if the dosage ratio of the solid powder to the preservative aqueous solution is not set properly, the comprehensive performance of the coffee grounds clay will also be reduced.

[0100] It can be seen from Example 1 and Comparative Example 9 that if the compaction pressure is not set properly, the comprehensive performance of the coffee grounds clay will also be reduced.

[0101] In addition, combined Figure 4 : Comparative Example 3: Coffee grounds clay prepared Figure 4 Right) After the drop resistance test, obvious cracks appeared on the surface, and the center of the sample was sunken compared to the surrounding area; while the coffee grounds clay prepared in Example 1 ( Figure 4 Left) After the drop resistance test, the sample surface was smooth and no obvious cracks appeared.

[0102] Combination Figure 6 : Comparative Example 2 The coffee grounds clay obtained by preparation ( Figure 6 Right) After the impact resistance test, multiple obvious and long cracks appeared, and there was local shedding; while the coffee grounds clay prepared in Example 1 ( Figure 6 Left) After the impact resistance test, the sample surface is smooth without obvious cracks or falling off.

[0103] In summary, in the preparation method of coffee residue clay provided by the present invention, the coffee residue material is used as the main component of the raw material for preparing clay. Its source is extensive, which can realize the recycling of coffee residue materials, turn waste into treasure, and at the same time greatly reduce the production cost of clay. In addition, the raw materials of the coffee residue clay are simple, the components are environmentally friendly, safe, non-toxic and harmless. The preparation method is simple and easy to operate. The obtained coffee residue clay has strong plasticity, can be processed repeatedly, has playability and interestingness. Moreover, it can be further processed by post-treatment such as polishing and coloring to prepare ornaments that can be stored for a long time and have both practical value and decorative value.

[0104] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing coffee grounds clay, characterized in that: The method comprises the following steps: mixing 50 parts of coffee grounds with 2.5 to 4 parts of xanthan gum and 16 to 20 parts of sodium carboxymethyl cellulose by weight to obtain solid powder; mixing the solid powder with 100 parts of preservative aqueous solution to obtain a plastic product; compacting the plastic product in a mold, and then demolding and drying.

2. The preparation method according to claim 1, characterized in that: The water content of the coffee grounds is not higher than 5wt%.

3. The preparation method according to claim 1 or 2, characterized in that: The coffee grounds material is obtained by drying the discarded coffee grounds at 40° C. to 50° C. for 45 hours to 50 hours.

4. The preparation method according to claim 1, characterized in that: The mass percentage of the preservative in the preservative aqueous solution is 0.1% to 0.3%.

5. The preparation method according to claim 4, characterized in that: The preservatives include potassium sorbate.

6. The preparation method according to claim 1, characterized in that: The preservative aqueous solution is added to the solid powder at least twice and mixed.

7. The preparation method according to claim 1, characterized in that: The compaction molding is carried out under a pressure of not less than 30N.

8. A coffee grounds clay, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 7.

9. The coffee grounds clay according to claim 8, characterized in that The volume shrinkage rate of the coffee grounds clay is 44% to 48%.

10. A decorative item, characterized in that: The raw materials for preparing the ornament include the coffee grounds clay as claimed in claim 8 or 9.

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