A plastic packaging cleaning agent that can be reused multiple times and its uses

Abstract

The present invention provides a plastic packaging cleaning agent that can be reused multiple times and its uses, which can provide a larger lipophilic space and stripping force; reduce the interfacial tension between the oil and water systems, and the free energy under the interfacial action decreases, so that the oil phase attached to the surface of the plastic material is more easily stripped. By adjusting the proportional relationship of the dosages of single-chain and multi-chain surfactants, the uncontrollability of the multi-chain surfactant with multiple lipophilic contact points is inhibited, and the synergistic compounding between different surfactants is achieved. The selection of the compounded surfactant can remove oil stains more quickly and stably compared with a single surfactant with a long-chain structure, thus achieving an efficient cleaning effect.

Description

Technical Field

[0001] The present invention relates to the technical field of plastic product recycling, in particular to a plastic lunch box cleaning agent that can be reused multiple times. Background Art

[0002] With the prevalence of the fast-food culture, the usage of various plastic outer packages is becoming more frequent. The usage rate of disposable plastic packaging products such as plastic lunch boxes (PP, PS), milk tea boxes, and beverage bottles has increased significantly. However, due to the chemical properties of the materials themselves, they are not easily degradable. A large amount of waste plastic garbage has increased the environmental burden. Whether it is landfilled or incinerated, it will have a serious negative impact on the ecosystem. Relying solely on its own degradation often requires a very long time. The safe, effective, and environmentally friendly method is to recycle and reuse it so that chemical materials can be recycled and reused twice.

[0003] Compared with unused new materials, it is difficult to avoid the performance attenuation of plastic recycling and reuse. The more impurity components it contains, the more serious the performance attenuation. Especially for plastic lunch boxes, a large amount of food residues, oil stains and other impurities are often attached to them, and it is not possible to effectively reuse them simply by recycling. Therefore, the plastic recycling process usually includes steps such as crushing, cleaning, and granulation, among which the cleaning process is particularly important. Without a thorough cleaning step, a large amount of oil stains, food residues and other impurities are attached to the surface of the recycled plastic. The plastics obtained after granulation have poor mechanical properties, turbidity, glossiness, etc. The recycled materials have limited applications, the recyclability is not high, and the value of the recycled plastics is greatly reduced. Therefore, choosing a suitable plastic cleaning agent is the key to recycling plastic products.

[0004] Patent 20141078340.2 discloses a waste plastic bottle cleaning agent, which mainly includes 16-20 parts of sodium tripolyphosphate, 11-15 parts of citric acid, 11-15 parts of lactic acid, 23-26 parts of phosphoric acid, 11-15 parts of sodium alkylbenzene sulfonate, and 70-90 parts of water. It can be used to clean the plastic bottle body, but its synthesis process is complicated and the removal effect on daily life oil stains is not ideal.

[0005] Patent 20151030200.6 provides a plastic cleaning agent, which is composed of the following weight percentage components: 10-20% of ethyl methylbenzene, 10-30% of diethylbenzylamine, 30-40% of diethylenetriamine, and 20-40% of ethyl methylbenzene. Although it can simply and efficiently remove the stains on the plastic surface, a large amount of wastewater is generated during the cleaning process, the decontamination efficiency is low, and it cannot quickly and thoroughly remove the oil stain components on the plastic surface, and the decontamination efficiency is significantly insufficient.

[0006] Patent 201811430562.4 developed an environmentally friendly recyclable plastic cleaning powder, which reduces the discharge of wastewater containing COD and can be recycled. However, this cleaning powder only uses a single non-ionic surfactant, sodium lauryl ether sulfate (AEO), resulting in serious attenuation of plastic properties and being unfavorable for the further effective utilization of plastics.

[0007] Due to the lipophilic characteristics of its own structure, the stains on the surface of plastic packaging have strong adhesion and are difficult to remove. Therefore, effectively separating the stains from the plastic lunch box, without damaging the chemical properties of the plastic surface, and at the same time controlling the discharge of wastewater containing COD are the technical problems of current cleaning agents. Summary of the Invention

[0008] In order to solve the deficiencies existing in the prior art, the present invention provides a plastic packaging cleaning agent that can be reused multiple times, which can efficiently peel off and remove the stains on the plastic surface, meet the performance requirements for the subsequent reuse of plastics. At the same time, the cleaning agent can be recycled, does not produce a large amount of industrial wastewater, and reduces the environmental load.

[0009] The cleaning agent uses the synergistic effect between anionic and non-ionic surfactants as the main agent, and auxiliary alkaline substances, penetrants, and activation promoters to improve the oil stain permeability and enhance the compatibility between surfactants. The addition of sodium oxide can remove harmful microorganisms, prevent the growth of bacteria on the plastic surface, and achieve the effect of sterilization, further ensuring the effective utilization of the recycled plastic products.

[0010] Based on the structural characteristics of anionic and non-ionic surfactants, the present invention designs the oil stain peeling strength. Through experiments, it is found that when the dosage ratio relationship of specific anionic and non-ionic surfactants is satisfied, the oil stain peeling effect of the cleaning agent is significantly better than that of a single type of surfactant. The activation promoter can make the oil phase finely dispersed, solve the problem of uneven arrangement of multi-branched non-ionic surfactants, and the mechanical properties of the renewable plastic particles obtained after cleaning remain excellent. The surface of the cleaned plastic packaging is smooth, odorless, and there is no chemical damage to the plastic during the cleaning process. The light transmittance and mechanical properties remain excellent, and the recycled plastic particles have broad application prospects.

[0011] The object of the present invention can be achieved by the following technical solutions: A plastic packaging cleaning agent that can be reused multiple times, calculated by weight, includes: 50 - 80 parts of surfactant a, 5 - 10 parts of alkaline substance b, 10 - 20 parts of sodium oxide c, and 5 - 15 parts of penetrant d.

[0012] Further, the surfactant a includes a C12-C18 non-ionic surfactant and / or an anionic surfactant; the non-ionic surfactant is one of sorbitan monostearate and sorbitan tristearate; preferably sorbitan tristearate; the anionic surfactant is one of sodium octadecenoate and sodium dodecylbenzenesulfonate; preferably sodium octadecenoate.

[0013] More preferably, in the surfactant a, the weight ratio of the non-ionic surfactant to the anionic surfactant is 1:1-4, preferably 1:3.

[0014] The basic substance b is sodium hydroxide and / or potassium hydroxide.

[0015] The sodium oxide salt c is sodium persulfate.

[0016] The penetrant d is a C12-C18 long-chain fatty acid, preferably one or more of palmitic acid, α-linolenic acid, and stearic acid.

[0017] Furthermore, the cleaning agent further contains 5-15 parts of an activation promoter e, which is selected from one or more of coconut oil fatty acid diethylamide, triethanolamine, and diethanolamine, preferably a mixture of coconut oil fatty acid diethylamide and triethanolamine, and the weight ratio of the two in the mixture is 1:1.

[0018] In addition, the present invention also provides a use process of the cleaning agent, and the specific process is as follows:

[0019] S1. Select plastic food packaging and add it to a mechanical crusher for crushing;

[0020] S2. Prepare a cleaning solution by mixing the cleaning agent and water in a ratio, and set it aside;

[0021] S3. Immerse the crushed plastic into the cleaning solution, and set an ultrasonic step for ultrasonic cleaning;

[0022] S4. Spray the cleaned plastic fragments with clear water;

[0023] S5. Wait for the fragments to air dry naturally, and at the same time collect the cleaning wastewater, add 10-20 parts of a precipitation promoter to promote the formation of solids, let it stand for stratification to remove impurities to obtain an aqueous phase, and further add the aqueous phase back to S2 for recycling;

[0024] S6. Add the air-dried plastic fragments to an extruder for granulation to obtain renewable plastic particles.

[0025] The plastic food packaging is selected from one of a polypropylene lunch box, a polypropylene milk tea cup, a polystyrene lunch box, a polyethylene milk carton, a polyethylene film, and a PET plastic water bottle.

[0026] The preparation ratio of the cleaning agent to water is 1 g:(10 - 50) g, the ultrasonic cleaning time is 5 - 30 min, and the spraying treatment time is 1 - 10 min.

[0027] Regarding the use process, the precipitation promoter is one or more of sodium chloride and sodium sulfate.

[0028] The present invention has the following beneficial effects:

[0029] (1) The present invention selects long-chain surfactants with C12 - 18. The hydrophobic group extends better in the oil phase, providing a larger lipophilic space and stripping force; under the interlacing entanglement of multi-arms and long-chain alkyl groups, the surfactant molecules are closely arranged between the oil and water phases, further reducing the interfacial tension between the oil and water systems, and the free energy under the interfacial action decreases, so that the oil phase attached to the plastic material surface is more easily stripped out.

[0030] (2) By adjusting the proportional relationship between the dosages of single-chain and multi-chain surfactants, the present invention inhibits the uncontrollability of multi-chain surfactants with multiple lipophilic contact points, and realizes the synergistic compounding between different surfactants. Compared with single long-chain structure surfactants, the selection of compounded surfactants removes oil stains more quickly and stably, thus achieving an efficient cleaning effect.

[0031] (3) The use of the activation promoter and penetrant in the present invention promotes the oil-water interface effect of the cleaning system, disperses the oil into smaller particle size droplets. Through the spatial size effect, the further dispersion of the oil phase droplets makes up for the defect of uneven interfacial arrangement of multi-chain surfactants, which is conducive to the rapid capture and complete stripping of oil stains. The obtained recycled plastic has a high mechanical property retention rate and good reusability.

[0032] (4) The present invention adopts a recycling method to reuse the wastewater after washing, eliminating the discharge of wastewater rich in COD, ensuring both plastic recycling and not bringing an additional burden to the green ecology. At the same time, the use of the precipitation promoter sodium chloride or sodium sulfate improves the layering effect through the salting-out effect by increasing the sodium ion concentration in the system, obtaining the aqueous phase more quickly and effectively. The impurities settle thoroughly, and the obtained aqueous phase after layering is clear and transparent without obvious visible substances dispersed in the aqueous phase, thus providing a basis for the recycling of the washing liquid. Specific Embodiments

[0033] The following will further illustrate the present invention in combination with specific embodiments, but the embodiments do not limit the present invention in any form. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

[0034] Synthesis Examples 1 - 8

[0035] The composition of the plastic packaging cleaning agent that can be reused multiple times is shown in Table 1. According to the dosage of each component shown in Table 1, the target cleaning agent is mixed and prepared.

[0036] Table 1:

[0037]

[0038] Comparative Synthesis Example 1

[0039] Compared with Example 2, in this comparative example, 20 parts of sp65 and 60 parts of sodium octadecenoate in the components are replaced by 80 parts of sp65, and the preparation of other components is the same as that of Example 2.

[0040] Comparative Synthesis Example 2

[0041] Compared with Example 2, in this comparative example, 20 parts of sp65 and 60 parts of sodium octadecenoate in the components are replaced by 80 parts of sodium octadecenoate, and the preparation of other components is the same as that of Example 2.

[0042] Comparative Synthesis Example 3

[0043] Compared with Example 2, in this comparative example, 20 parts of sp65 and 60 parts of sodium octadecenoate in the components are replaced by 60 parts of sp65 and 20 parts of sodium octadecenoate, and the preparation of other components is the same as that of Example 2.

[0044] Comparative Synthesis Example 4

[0045] Compared with Example 2, in this comparative example, the activation promoter is missing in the components, and other components are the same as those of Example 2.

[0046] Comparative Synthesis Example 5

[0047] Compared with Example 2, in this comparative example, the penetrant is missing in the components, and other components are the same as those of Example 2.

[0048] Comparative Synthesis Example 6

[0049] Compared with Example 2, in this comparative example, 5 parts of triethanolamine and 5 parts of coconut oil fatty acid diethylamide in the components are replaced by 20 parts of triethanolamine, and other components are the same as those of Example 2.

[0050] Specific Test Examples (Examples 1 - 8, Comparative Examples 1 - 6)

[0051] Test content: The usage method steps of the plastic packaging cleaning agent that can be reused multiple times are as follows:

[0052] S1. Select a plastic lunch box made of polypropylene and add it to a mechanical crusher, and crush it to a size < 2 cm;

[0053] S2. Prepare cleaning solutions by mixing the cleaning agents in Synthesis Examples 1-8 and Comparative Synthesis Examples 1-6 with water at a ratio of 1 g:20 g, and set aside for later use.

[0054] S3. Immerse the shredded plastics into the cleaning solution, and simultaneously perform ultrasonic cleaning with ultrasonic steps for 10 minutes.

[0055] S4. Spray the cleaned plastic fragments with clear water for 5 minutes.

[0056] S5. Wait for the fragments to air dry naturally. Meanwhile, collect the cleaning wastewater, add 10 parts of sodium chloride to promote the formation of solids, let it stand for layer separation to remove impurities to obtain the aqueous phase, and further recycle the aqueous phase by adding it back to S2.

[0057] S6. Add the air-dried plastic pellets into an extruder for pelletizing to obtain renewable plastic pellets.

[0058] The method for testing the stain removal rate is as follows:

[0059] Take a fixed amount of clean and unused polypropylene plastic lunch boxes, break them, weigh the total weight of the fragments, denoted as M1; immerse the fragments completely in edible soybean oil, take them out, drain until no liquid drips, and then weigh the total weight of the fragments, denoted as M2; clean the fragments according to steps S2-S5 in the corresponding Examples 1-8 and Comparative Examples 1-6 until the fragments are air-dried naturally to ensure no moisture remains, and then weigh the total weight of the fragments, denoted as M3.

[0060] Stain removal rate = (M2 - M3) / (M2 - M1) × 100%.

[0061] Furthermore, conduct tensile strength, impact strength, and light transmittance tests on the renewable plastic pellets obtained in Examples 1-8 and Comparative Examples 1-6. The tensile strength test standard refers to GB / T 1040.2-2006, the notched impact strength test standard refers to GB / T1843-2008, and the light transmittance test standard refers to GB / T 2410-2008. The test results are shown in Table 2.

[0062] Table 2:

[0063]

[0064]

[0065] According to the experimental results, the reusable plastic packaging cleaning agent prepared by the present invention has a stain removal rate of more than 97.3%, a light transmittance of more than 79.3%; in addition, the mechanical property retention rates are all maintained above 90%, and the impact strength retention rate can reach up to 98.1% at most. That is, while meeting the stain removal rate, it not only ensures the light transmittance of the product, but also inhibits the attenuation of the mechanical property strength, making the application field of renewable plastics wider and no longer limited to the uses in the low-cost and low-end market of recycled materials.

[0066] In addition, the present invention further studied the influence of the cleaning agent on the physical and chemical properties of plastic packaging during the cleaning process and the residual situation of the cleaning agent itself (except for oil removal). Therefore, Example 2 with the best comprehensive performance in Table 2 was selected as the cleaning agent of the present invention and the unused PP raw material was used for experiments. That is, the same steps S1-S6 as in Example 2 were selected to conduct experiments on the unused PP raw material, and the performance changes of the PP raw material and the residual situation of the cleaning agent were tested.

[0067] Comparative example: A cleaning powder was prepared using the component raw materials in Example 1 of Patent 201811430562.4, and it was formulated into a cleaning solution with water at a ratio of 1 g:20 g to clean the PP raw material. The above cleaning steps were the same as S2-S6 of the present invention.

[0068] The test method for the residual rate of the cleaning agent is as follows:

[0069] Take a fixed amount of clean and unused PP raw material and crush it, weigh the total weight of the fragments, denoted as m1; wash the fragments according to steps S2-S5 until the fragments are naturally dried to ensure no moisture, and then weigh the total weight of the fragments, denoted as m2.

[0070] Residual rate of cleaning agent = (m2 - m1) / m1 × 100%.

[0071] The test results are shown in Table 3:

[0072] Table 3:

[0073]

[0074]

[0075] Judging from the test results of the blank PP raw material, the cleaning agent components remaining on the plastic packaging after being cleaned with the cleaning agent of the present invention only contain 0.02%, and its harmful residual components to the human body are far lower than the national standard, which greatly guarantees the application prospect of recycled plastic products. For example, it is also applicable to the field of food contact; and the mechanical properties after cleaning are hardly affected, which also shows that the cleaning agent will not cause obvious structural damage to the plastic itself, further expanding the applicable market of recycled plastics.

[0076] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, 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 plastic packaging cleaning agent that can be reused multiple times, calculated by weight, includes: 50 - 80 parts of surfactant a, 5 - 10 parts of alkaline substance b, 10 - 20 parts of sodium oxide salt c, 5 - 15 parts of penetrant d, 5 - 15 parts of activation promoter e; The surfactant a includes a C12 - C18 non - ionic surfactant and an anionic surfactant. The non - ionic surfactant is one of sorbitan monostearate and sorbitan tristearate; the anionic surfactant is one of sodium octadecenoate and sodium dodecylbenzenesulfonate, and the weight ratio of the non - ionic surfactant to the anionic surfactant is 1:1 - 4; The penetrant d is a C12 - C18 long - chain fatty acid; The activation promoter e is selected from one or more of coconut oil fatty acid diethylamide, triethanolamine, and diethanolamine; The sodium oxide salt c is sodium persulfate.

2. The cleaning agent according to claim 1, wherein the non - ionic surfactant is sorbitan tristearate and the anionic surfactant is sodium octadecenoate.

3. The cleaning agent according to claim 1, wherein in the surfactant a, the weight ratio of the non - ionic surfactant to the anionic surfactant is 1:

3.

4. The cleaning agent according to claim 1, wherein the alkaline substance b is sodium hydroxide and / or potassium hydroxide.

5. The cleaning agent according to claim 1, wherein the penetrant d is one or more of palmitic acid, α - linolenic acid, and stearic acid.

6. The cleaning agent according to claim 1, wherein the activation promoter e is a mixture of coconut oil fatty acid diethylamide and triethanolamine, and the weight ratio of the two in the mixture is 1:

1.

7. The usage process of the cleaning agent according to claim 1 is as follows: S1. Select plastic food packaging and add it to a mechanical crusher for crushing; S2. Prepare a cleaning solution by mixing the cleaning agent and water in a certain proportion for standby; S3. Immerse the crushed plastic into the cleaning solution, and at the same time set an ultrasonic step for ultrasonic cleaning; S4. Spray - rinse the cleaned plastic fragments with clean water; S5. Wait for the fragments to air - dry naturally. At the same time, collect the cleaning wastewater, add 10 - 20 parts of a precipitation promoter to promote the formation of solids, let it stand for stratification to remove impurities to obtain the aqueous phase, and further recycle the aqueous phase back to S2. The precipitation promoter is one or more of sodium chloride and sodium sulfate; S6. Add the air - dried plastic fragments to an extruder for granulation to obtain renewable plastic particles.

8. The usage process according to claim 7, wherein the plastic food packaging is selected from one of polypropylene lunch boxes, polypropylene milk tea cups, polystyrene lunch boxes, polyethylene milk cartons, polyethylene films, and PET plastic water bottles.

9. The usage process according to claim 7, wherein the preparation ratio of the cleaning agent to water is 1g:(10 - 50)g, the ultrasonic cleaning time is 5 - 30 min, and the spray - rinsing treatment time is 1 - 10 min.

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