Freezer-resistant PLA composite and method of making same

Abstract

The application belongs to the technical field of materials, and particularly relates to a kind of cold-resistant PLA composite material and its preparation method. According to the total weight of raw materials 100 parts, the raw material composition of the cold-resistant PLA composite material includes: PLA 45-70 parts, anti-freezing modifier 14-25 parts, reinforcing agent 14-25 parts and compatibility agent 1-5 parts. The application selects polyhydroxyalkanoate as the toughening agent of the main base material, and polycaprolactone as the auxiliary toughening agent. Under the cooperation of the two, the toughness and better low-temperature freezing resistance characteristics obtained are better than those obtained by adding each alone. The nano talc powder is matched with modified starch, the body rigidity is moderate, the film is poked and crystallized while the better low-temperature freezing resistance characteristics are obtained. The acrylate copolymer is used as the compatibility agent, and the anti-freezing modifier produces a synergistic effect, further improving the low-temperature freezing resistance characteristics of the material. The product has obvious effect, and has broad commercial application prospect and market value.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of materials, and in particular relates to a cold-resistant PLA composite material and a preparation method thereof. BACKGROUND

[0002] At present, the main way of drinking drinks such as milk tea and juice is still the straw. In order to prevent plastic garbage pollution, biodegradable plastic materials and paper are mainly used to replace non-degradable materials such as polypropylene straws.

[0003] For paper straws, using pure paper products has the problems of complete opacity, low strength, deformation and softening after soaking, loss of functionality, and poor use experience. If the inner and outer layers of the paper straw are treated to prevent water, the process is complicated, the efficiency is reduced, the cost is increased, and the classification and recycling are difficult.

[0004] Among biodegradable plastic materials, CPLA straws have the highest cost performance and the best safety. At present, CPLA straws are also used more and more widely.

[0005] However, CPLA straws will crack under stress at low temperatures, especially at zero temperature. For example, if the straw is pinched at an ambient temperature of -11 DEG C, it will crack with a high probability. The lower the temperature, the more serious the stress cracking phenomenon. In the past, in the northern region in winter, a large amount of economic loss was caused by the frequent returns of straws due to cracking at low temperatures.

[0006] Therefore, the present application is proposed. SUMMARY

[0007] The present application aims to provide a cold-resistant PLA composite material and a preparation method thereof. The straw made of the composite material of the present application has the characteristics of easy puncture film, high temperature resistance and low temperature resistance after crystallization, meets the actual needs of low temperature environment and low temperature region, reduces the risk and expands the use range.

[0008] To achieve the purpose of the present application, the present application adopts the following technical solutions:

[0009] A cold-resistant PLA composite material, wherein, according to the total weight of 100 parts of raw materials, the raw material composition of the cold-resistant PLA composite material comprises:

[0010]

[0011] The straw made of the cold-resistant PLA composite material made of the above raw materials has the characteristics of easy puncture film, high temperature resistance and low temperature resistance after crystallization. The high temperature resistance after crystallization is above 75 DEG C, the low temperature resistance can reach -15 DEG C, and the breakage rate after pinching at low temperature is greatly reduced.

[0012] Further, the PLA is L-PLA and its copolymer.

[0013] The D-PLA and its copolymer have adverse effects, and the L-PLA is harmless to organisms.

[0014] Further, the melting point of the L-PLA is 150-175℃, and the melt index is 4-10g / 10min.

[0015] The melt index of the L-PLA has a certain influence on the performance of the straw. When the melt index is less than 4g / 10min, the extrusion resistance of the straw is large; when the melt index is greater than 10g / 10min, the melt strength is low, and the thickness deviation is large. Therefore, as a preferred solution, the melt index of the L-PLA in the application is 4-10g / 10min.

[0016] As a preferred solution, the L-PLA used in the application is FY801 of Fuxing.

[0017] Further, the anti-freezing modifier is a mixture of polycaprolactone (PCL) and polyhydroxyalkanoate (PHACT).

[0018] The anti-freezing modifier of the application creatively selects polyhydroxyalkanoate (PHACT) as the main toughening agent of the base material, and polycaprolactone (PCL) as the auxiliary toughening agent. In combination with the two, the toughness obtained is better than that obtained by adding each alone, and better low-temperature freezing resistance is obtained.

[0019] Further, the anti-freezing modifier is a mixture of polycaprolactone and polyhydroxyalkanoate in a mass ratio of 1:2.5-4.

[0020] As a preferred solution, the polycaprolactone (PCL) used in the application is kapa PCL 6800; and the polyhydroxyalkanoate (PHACT) used in the application is A1000P of CJ.

[0021] Further, the reinforcing agent is a mixture of nano-talc powder and modified starch.

[0022] The reinforcing agent of the application creatively combines nano-talc powder with modified starch, and the body rigidity is moderate, which can ensure the piercing of the film and crystallization of the straw at the same time, and better low-temperature freezing resistance is obtained.

[0023] Further, the reinforcing agent is a mixture of nano-talc powder and modified starch in a mass ratio of 4-15:1.

[0024] The reinforcing agent in the application is mainly talcum powder, if the amount of modified starch is too high, the rigidity will be insufficient. In the application, the reinforcing agent is a mixture of nano talcum powder and modified starch in a mass ratio of 4-15:1.

[0025] As a preferred solution, in the application, the nano talcum powder used is Shenba Nano Talc, and the modified starch used is self-made modified starch.

[0026] Further, the compatibilizer is an acrylate copolymer.

[0027] In the application, the acrylate copolymer is used as a compatibilizer to produce a synergistic effect with the anti-freezing modifier, further improving the low-temperature freezing resistance of the material.

[0028] As a preferred solution, in the application, the acrylate copolymer used is Orevac T9307Y of SKEP.

[0029] The application also provides a preparation method of the freezing-resistant PLA composite material, comprising the following steps:

[0030] 1) adding PLA and anti-freezing modifier into a sealed mixing pot, heating and stirring;

[0031] 2) adding reinforcing agent and compatibilizer and stirring;

[0032] 3) discharging, and melt-extruding and granulating by an extruder to obtain the freezing-resistant PLA composite material.

[0033] Further, in step 3), the melt-extrusion temperature is 140-190℃, and the main machine speed of the extruder is 400-600 rpm.

[0034] Further, in step 1), the heating is to 50-60℃, and the stirring time is 3-8 minutes.

[0035] Further, in step 2), the stirring time is 2-4 minutes.

[0036] Compared with the prior art, the application has the following advantages:

[0037] (1) In the application, polyhydroxyalkanoate is creatively selected as a toughening agent of the main base material, and polycaprolactone is creatively selected as an auxiliary toughening agent, and the toughness obtained by the cooperation of the two is better than that obtained by adding each alone, and better low-temperature freezing resistance is obtained.

[0038] (2) In the application, nano talcum powder and modified starch are creatively combined, the rigidity is moderate, the film puncture and crystallization of the straw can be ensured at the same time, and better low-temperature freezing resistance is obtained.

[0039] (3) The acrylic ester copolymer as the compatilizer in the application has a synergistic effect with the anti-freezing modifier, and further improves the low-temperature freezing resistance of the material.

[0040] (4) The process is simple, the product effect is obvious, meets the market demand, and has broad commercial application prospects and market value. DETAILED DESCRIPTION

[0041] The following is a specific embodiment of the application, and the examples are described to further illustrate the application, but not to limit the application.

[0042] EMBODIMENTS

[0043] The raw material composition of the cold-resistant PLA composite provided by the application comprises, based on 100 parts of the total weight of the raw materials:

[0044]

[0045] The preparation method comprises the following steps:

[0046] 1) Add PLA and anti-freezing modifier into a sealed mixing pot, heat and stir;

[0047] 2) Add reinforcing agent and compatilizer, and stir;

[0048] 3) Discharge, melt and extrude to obtain the cold-resistant PLA composite.

[0049] The specific composition and process parameters of each embodiment are shown in Table 1:

[0050] Table 1

[0051]

[0052]

[0053] In the above Table 1, FY801 is FY801 of Fong Yuan, A1000P is A1000P of CJ, PCL 6800 is kapaPCL6800, Nano TALC is Shengba Nano Talc, 9307Y is Orevac T 9307Y of SKEP, and the modified starch is obtained by the following method:

[0054] Add starch into a stirring pot, add food-grade glycerol during stirring, continue to add less than 0.5% of pentaerythritol ester and less than 1% of N,N'-1,2-ethylenediamine octadecylamide by mass ratio, continue to stir for 5 minutes after the addition is completed, and then vacuum dry to obtain the modified starch.

[0055] The following are examples 6 to 8, wherein the preparation method is the same as example 1, and the components are shown in table 2:

[0056] Table 2

[0057]

[0058] In table 2, the anti-freezing modifier, reinforcing agent and compatibilizer used are the same as examples 1-5, specifically, the polyhydroxyalkanoate used is A1000P of CJ, the polycaprolactone used is kapa PCL 6800, the nano talc used is Shengba Nano Talc, the acrylate copolymer used is Orevac T 9307Y of SKEP, and the modified starch used is self-made according to the aforementioned method.

[0059] Comparative examples

[0060] The components of the comparative examples are the same as example 1, except that the selection and amount of the components are different, as shown in table 3:

[0061] Table 3

[0062]

[0063] The preparation method used in each comparative example is the same as example 1.

[0064] Test example 1

[0065] This test example investigates the performance of the composite materials prepared in examples 1-5 and comparative examples of the present application.

[0066] Method: The prepared composite materials are dried in a dehumidifying drying box at 85°C for 4 hours, and 2.5 gram straws are produced by a straw machine, and 100 straws are drawn to evaluate the low-temperature freezing, and the low-temperature freezing evaluation environment is a-15°C freezing refrigerator. 100 straws after crystallization are drawn to evaluate the film puncture, and the number of broken films ≥98 is qualified. 100 straws after crystallization are drawn to stir clockwise for 15 circles and counterclockwise for 15 circles in a 75°C constant temperature water bath, and the number of non-softening deformation ≥98 is qualified.

[0067] The results are shown in the following table 4:

[0068] Table 4

[0069]

[0070]

[0071] From the results of Table 3 above, it can be seen that: comparing Comparative Example 1, Comparative Example 2 with Example 2, using PCL alone or PHACT alone does not have as good a low temperature resistance as the combination of the two, and using a large amount of PCL alone can result in the film not meeting the requirements for puncture resistance and heat resistance. Comparing Comparative Example 3, Comparative Example 4 with Example 2, using nano talc powder alone or modified starch alone does not have as good a low temperature resistance as the combination of the two, and using a large amount of modified starch alone can result in the film not meeting the requirements for heat resistance. Comparing Example 2 with Comparative Example 5, not using a compatibilizer can greatly increase the low temperature breakage rate of the straw after crystallization. Comparing Example 2 with Comparative Example 6, not adding an anti-freezing agent can result in 100% breakage of the straw at low temperature after crystallization.

Claims

1. A freeze resistant PLA composite, characterized in that, The raw material composition of the freeze-resistant PLA composite comprises, based on 100 parts of the total weight of the raw material: PLA 45-70 parts Anti-freezing modifier 14-25 parts Reinforcing agent 14-25 parts Compatibility agent 1-5 parts The anti-freezing modifier is a mixture of polycaprolactone and polyhydroxyalkanoate in a mass ratio of 1:2.5-4; The reinforcing agent is a mixture of nano-talc powder and modified starch in a mass ratio of 4-15:1; The polyhydroxyalkanoate PHACT used is A1000P of CJ.

2. The freeze-resistant PLA composite of claim 1, wherein, The PLA is levorotatory PLA.

3. The freeze-resistant PLA composite of claim 2, wherein, The melting point of the levorotatory PLA is 150-175℃, and the melt index is 4-10 g / 10 min.

4. A method of producing the freeze-resistant PLA composite according to any one of claims 1 to 3, characterized in that, The preparation method comprises the following steps: 1) adding PLA and anti-freezing modifier into a sealed mixing pot, heating, and stirring; 2) adding reinforcing agent and compatibility agent, and stirring; 3) discharging, and melt-extruding and granulating by an extruder to obtain the freeze-resistant PLA composite.

5. The preparation method according to claim 4, characterized in that, In step 3), the melt-extrusion temperature is 140-190℃, and the main machine rotating speed of the extruder is 400-600 rpm.

6. The production method according to claim 5, wherein In step 1), the heating is heating to 50-60℃, and the stirring time is 3-8 minutes.

7. The preparation method according to claim 6, characterized in that, In step 2), the stirring time is 2-4 minutes.

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