Preparation method of PLA (polylactic acid) matrix lead standard sample and standard sample thereof

Abstract

The preparation method comprises the following steps: uniformly mixing PLA plastic and a plasticizer in a closed system, adding toner, uniformly mixing, and carrying out melt extrusion granulation to obtain a PLA blank master batch; the preparation method comprises the following steps: uniformly mixing PLA plastic and a plasticizer in a closed system, adding uniformly mixed additives and toner, uniformly mixing, and carrying out melt extrusion granulation to obtain PLA mixed master batches; uniformly mixing the PLA mixed master batch and the PLA blank master batch in equal proportion, and performing melt extrusion granulation twice to obtain a lead standard sample; wherein the lead content in the PLA plastic and the PLA blank master batch is lower than the lead content in the PLA mixed master batch. According to the technical scheme, the reagent containing the target element is added into the PLA matrix particles to prepare the high-concentration PLA concentrated master batch, and then the high-concentration PLA concentrated master batch particles and the PLA blank master batch particles are mixed, so that the PLA matrix standard sample with the low-concentration lead limit value is obtained, the uniformity is guaranteed, meanwhile, the processing frequency is reduced, and the stability of PLA is improved.

Description

Technical Field

[0001] The invention relates to the technical field of chemicals, and in particular to a preparation method of a lead standard sample of a PLA matrix and a standard sample thereof. Background Art

[0002] Polylactic acid (PLA), also known as polylactide, is a polyester polymer obtained by polymerization with lactic acid as the main raw material. It is a new type of biodegradable material. The absolutely harmless property of polylactic acid to the human body makes polylactic acid have unique advantages in the field of disposable products such as disposable tableware and food packaging materials. Polylactic acid is highly safe for the human body and can be absorbed by tissues. In addition, its excellent physical and mechanical properties can also be used in the field of biomedicine. With the implementation of policies such as "plastic restriction" and "plastic ban" to control plastic pollution, the biodegradable plastic industry represented by PLA has rapidly emerged, and biodegradable plastic products have been widely used. The problems faced by market supervision, inspection and testing need to be solved urgently.

[0003] Biodegradable materials such as polylactic acid are the main raw materials for the production of biodegradable plastics. In order to improve the performance of biodegradable plastic products, additives such as plasticizers, flame retardants, reinforcers and fillers such as industrial starch, talcum powder, titanium dioxide are added during the production and processing process. This will introduce health hazards such as heavy metals into the products. The health hazards and safety issues caused by this cannot be ignored.

[0004] Research the preparation technology of standard substances of heavy metal elements in polylactic acid, prepare national standard samples, fill the gap of standard substances of heavy metals in polylactic acid in my country, and apply the research results to heavy metal detection quality control, measurement assessment, proficiency verification, inter-laboratory comparison and international recognition. It can also be further applied to the research and development of heavy metal standard substances for soil, water, food and food contact materials, which is of great significance for strengthening the control of heavy metals and other pollutants in polylactic acid and protecting the environment and human health and safety.

[0005] In summary, how to prepare a PLA matrix standard sample with a low lead concentration limit is a problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0006] The main purpose of the embodiment of the present invention is to provide a method for preparing a lead standard sample of a PLA matrix and a standard sample thereof, aiming to prepare a PLA matrix standard sample with a low lead concentration limit.

[0007] The technical solution of the present invention to solve the above technical problem is to provide a method for preparing a lead standard sample based on a PLA matrix, comprising the following steps:

[0008] PLA plastic and plasticizer are mixed evenly in a closed system, color powder is added and mixed evenly, and melt extrusion granulation is performed to obtain PLA blank masterbatch;

[0009] PLA plastic and plasticizer are mixed evenly in a closed system, and the mixed additives and color powder are added, mixed evenly again, and melt-extruded and granulated to obtain PLA mixed masterbatch;

[0010] The PLA mixed masterbatch and the PLA blank masterbatch were mixed evenly in equal proportions, and melt-extruded and granulated twice to obtain a lead standard sample;

[0011] Among them, the lead content in PLA plastic and PLA blank masterbatch was lower than that in PLA mixed masterbatch.

[0012] Furthermore, the lead content of the PLA plastic is 0.1 mg / kg-10 mg / kg.

[0013] Furthermore, in the step of uniformly mixing the PLA plastic and the plasticizer in a closed system, uniformly adding the color powder, and uniformly mixing, and melt-extruding and granulating to obtain the PLA blank masterbatch, the melt-extrusion temperature is 150° C.-200° C.

[0014] Furthermore, in the step of uniformly mixing PLA plastic and plasticizer in a closed system, adding the mixed additive and color powder, uniformly mixing again, and melt-extruding and granulating to obtain PLA mixed masterbatch, the melt extrusion temperature is 155°C-200°C.

[0015] Furthermore, in the step of uniformly mixing the PLA mixed masterbatch and the PLA blank masterbatch in equal proportions, and melt-extruding and granulating them twice to obtain the lead standard sample, the melt extrusion temperature is 155° C.-200° C.

[0016] Furthermore, the plasticizer is TBC; and / or the colorant is TiO2.

[0017] Furthermore, the licking material is at least one of lead stearate, copper stearate, zinc stearate, and cadmium stearate.

[0018] In order to solve the above technical problems, the present application also proposes a lead standard sample of a PLA matrix, comprising the following components in parts by weight:

[0019] PLA pellets 100-200 parts;

[0020] Plasticizer 5-10 parts;

[0021] Color powder 5-10 parts;

[0022] 0-5 servings of licking material.

[0023] Furthermore, the plasticizer is TBC; and / or the colorant is TiO2.

[0024] Furthermore, the licking material is at least one of lead stearate, copper stearate, zinc stearate, and cadmium stearate.

[0025] The technical solution of the present invention first adds a reagent containing a target element to PLA matrix particles to prepare a high-concentration PLA concentrated masterbatch, and then mixes the high-concentration PLA concentrated masterbatch particles with PLA blank masterbatch particles to obtain a PLA matrix standard sample with a low concentration lead limit. This preparation method reduces the number of processing times and improves the stability of PLA while ensuring uniformity. It can also prepare lead standard samples of PLA matrices with different requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0027] Figure 1 The figure is a flow chart of the steps of the lead standard sample method for the PLA matrix according to the present invention. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the accompanying drawings of the present invention specification to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0030] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "several" or "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0031] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0033] The invention provides a preparation method of a lead standard sample of a PLA matrix and a standard sample thereof, aiming to prepare a PLA matrix standard sample with a low lead concentration limit.

[0034] The lead standard sample of the PLA matrix proposed in the present invention will be described in the following specific embodiments:

[0035] In the technical solution of this embodiment, Figure 1 As shown, a method for preparing a lead standard sample based on a PLA matrix comprises the following steps:

[0036] S10: PLA plastic and plasticizer are mixed evenly in a closed system, color powder is added and mixed evenly, and melt-extruded and granulated to obtain PLA blank masterbatch;

[0037] S20: PLA plastic and plasticizer are mixed evenly in a closed system, and the mixed additives and color powder are added, mixed evenly again, and melt-extruded and granulated to obtain PLA mixed masterbatch;

[0038] S30: uniformly mixing the PLA mixed masterbatch and the PLA blank masterbatch in equal proportions, and melt-extruding and granulating the mixture twice to obtain a lead standard sample;

[0039] Among them, the lead content in PLA plastic and PLA blank masterbatch was lower than that in PLA mixed masterbatch.

[0040] It can be understood that the present application first adds the reagent containing the target element to the PLA matrix particles to prepare a high-concentration PLA concentrated masterbatch, and then mixes the high-concentration PLA concentrated masterbatch particles with the PLA blank masterbatch particles to obtain a PLA matrix standard sample with a low concentration lead limit. This preparation method reduces the number of processing times and improves the stability of PLA while ensuring uniformity. And lead standard samples of PLA matrix with different requirements can be prepared.

[0041] Specifically, the preparation method of PLA plastic is as follows: dissolve the catalyst Sn(Oct)2 in n-hexane; then add it to the recrystallized LLA monomer, mix it evenly, place it in the DISCOVER microwave reactor, and use the Chem Driver software to set the reaction temperature, power and time; after rapidly heating to T1 temperature at 200W power, continue to heat to T2 temperature with 30W power and keep irradiating for a certain time. The two-step heating method can avoid the carbonization of the product caused by the high microwave power causing the polymerization reaction to surge, so that the temperature is more stably controlled at the set reaction temperature T2, and the obtained product is completely dissolved in chloroform, precipitated with anhydrous ethanol, and vacuum dried to constant weight at 40°C, and stored in a desiccator. Therefore, in the technical solution of the present invention, LLA bulk ring-opening polymerization under normal pressure is used to prepare PLA plastic as a substrate, and on this basis, the corresponding heavy metal standard sample can be obtained by adding stearate of heavy metal lead stearate.

[0042] In the technical solution of the present invention, an oily plasticizer is introduced to improve the distribution of additives and color powder in the PLA plastic raw material, effectively improve the uniformity, and minimize the number of processing times, thereby ensuring the uniformity of the PLA matrix standard sample while also ensuring stability.

[0043] In a feasible embodiment, the plasticizer is an oily plasticizer.

[0044] Furthermore, the lead content of the PLA plastic is 0.1 mg / kg-10 mg / kg.

[0045] Furthermore, in the step of uniformly mixing the PLA plastic and the plasticizer in a closed system, uniformly adding the color powder, and uniformly mixing, and melt-extruding and granulating to obtain the PLA blank masterbatch, the melt-extrusion temperature is 150° C.-200° C.

[0046] Furthermore, in the step of uniformly mixing PLA plastic and plasticizer in a closed system, adding the mixed additive and color powder, uniformly mixing again, and melt-extruding and granulating to obtain PLA mixed masterbatch, the melt extrusion temperature is 155°C-200°C.

[0047] Furthermore, in the step of uniformly mixing the PLA mixed masterbatch and the PLA blank masterbatch in equal proportions, and melt-extruding and granulating them twice to obtain the lead standard sample, the melt extrusion temperature is 155° C.-200° C.

[0048] Furthermore, the plasticizer is TBC; and / or the colorant is TiO2.

[0049] It can be immediately, the plasticizer is TBC, oily liquid;

[0050] Furthermore, the licking material is at least one of lead stearate, copper stearate, zinc stearate, and cadmium stearate.

[0051] It is understandable that a small amount of lead is inevitably present in plasticizers (additives) and color powders. In order to avoid the influence of residual contaminants on the accuracy, the purity of the additives and color powders must be ensured to be much lower than the expected concentration of lead standard samples in the PLA matrix.

[0052] In a possible embodiment, the additive is a stearate of a corresponding metal, wherein the metal is lead.

[0053] In order to solve the above technical problems, the present application also proposes a lead standard sample of a PLA matrix, comprising the following components in parts by weight:

[0054] PLA pellets 100-200 parts;

[0055] Plasticizer 5-10 parts;

[0056] Color powder 5-10 parts;

[0057] 0-5 servings of licking material.

[0058] Preferably, PLA pellets 100 parts; plasticizer 5 parts; color powder 5 parts; licking material 0-5 parts.

[0059] Furthermore, the plasticizer is TBC; and / or the colorant is TiO2.

[0060] Furthermore, the licking material is at least one of lead stearate, copper stearate, zinc stearate, and cadmium stearate.

[0061] Example 1

[0062] A method for preparing a lead standard sample of a PLA matrix comprises the following components: 20000 g of PLA plastic particles, 10 g of lead stearate, 100 g of a plasticizer (auxiliary agent), and 100 g of color powder.

[0063] The method comprises the following preparation steps:

[0064] 1) 20000g of PLA plastic particles, 100g of plasticizer (additive), and 100g of color powder were placed in a high-speed mixer and mixed evenly, and then melt-extruded and granulated at 150-200°C by a twin-screw extruder; blank masterbatch particles were prepared;

[0065] 2) 20000g of PLA plastic particles, 10g of lead stearate, 100g of plasticizer (additive), and 100g of color powder are placed in a high-speed mixer and mixed evenly, and then melt-extruded and granulated at 150-200°C by a twin-screw extruder to obtain concentrated masterbatch particles;

[0066] 3) 10000 g of PLA concentrated masterbatch and 10000 g of PLA blank masterbatch were placed in a high-speed mixer and mixed evenly, and then melt-extruded and granulated at 150-200° C. using a twin-screw extruder to obtain a lead standard sample with a lead content of 110 g / kg.

[0067] The prepared standard samples were pre-treated according to the heavy metal content requirements of 6.9.1 of GB / T 18006.3 "General requirements for disposable degradable tableware", and the lead content in the samples was detected using inductively coupled plasma mass spectrometry according to GB / T37837.

[0068] Table 1 Uniformity test data of standard samples:

[0069]

[0070] Table 2 Calculation data of uniformity of standard samples (without repeated two-factor analysis):

[0071]

[0072] Tables 1 and 2 are the standard sample uniformity test results and statistical results respectively; it can be seen from Tables 1 and 2 that F<Fcrit, indicating that the sample is uniform.

[0073] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preparing a lead standard sample based on a PLA matrix, characterized in that: The following steps are involved: PLA plastic and plasticizer are mixed evenly in a closed system, color powder is added and mixed evenly, and melt extrusion granulation is performed to obtain PLA blank masterbatch; PLA plastic and plasticizer are mixed evenly in a closed system, and the mixed additives and color powder are added, mixed evenly again, and melt-extruded and granulated to obtain PLA mixed masterbatch; The PLA mixed masterbatch and the PLA blank masterbatch were mixed evenly in equal proportions, and melt-extruded and granulated twice to obtain a lead standard sample; Among them, the lead content in PLA plastic and PLA blank masterbatch was lower than that in PLA mixed masterbatch.

2. The method for preparing a lead standard sample based on a PLA matrix according to claim 1, characterized in that: The lead content of the PLA plastic is 0.1 mg / kg-10 mg / kg.

3. The method for preparing a lead standard sample based on a PLA matrix according to claim 1, characterized in that: In the step of uniformly mixing PLA plastic and plasticizer in a closed system, adding color powder and mixing uniformly, and melt-extruding and granulating to obtain PLA blank masterbatch, the melt-extrusion temperature is 150° C.-200° C.

4. The method for preparing a lead standard sample based on a PLA matrix according to claim 1, characterized in that: In the step of uniformly mixing PLA plastic and plasticizer in a closed system, adding the mixed additive and color powder, uniformly mixing again, and melt-extruding and granulating to obtain PLA mixed masterbatch, the melt extrusion temperature is 155°C-200°C.

5. The method for preparing a lead standard sample based on a PLA matrix according to claim 1, characterized in that: In the step of uniformly mixing the PLA mixed masterbatch and the PLA blank masterbatch in equal proportions, and melt-extruding and granulating twice to obtain the lead standard sample, the melt-extrusion temperature is 155° C.-200° C.

6. The method for preparing a lead standard sample based on a PLA matrix according to claim 1, characterized in that: The plasticizer is TBC; And / or, the colorant is TiO2.

7. The method for preparing a lead standard sample based on a PLA matrix according to claim 1, characterized in that: The licking material is at least one of lead stearate, copper stearate, zinc stearate and cadmium stearate.

8. A lead standard sample based on PLA, characterized in that: The composition comprises the following components in parts by weight: PLA pellets 100-200 parts; Plasticizer 5-10 parts; Color powder 5-10 parts; 0-5 servings of licking material.

9. The lead standard sample based on PLA according to claim 8, characterized in that: The plasticizer is TBC; And / or, the colorant is TiO2.

10. The lead standard sample based on PLA according to claim 8, characterized in that: The licking material is at least one of lead stearate, copper stearate, zinc stearate and cadmium stearate.

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