CN113831697B

CN113831697B - Application of lignin in preparation of degradable chemical foaming material

Info

Publication number: CN113831697B
Application number: CN202111202821.XA
Authority: CN
Inventors: 朱晨杰; 应汉杰; 庄伟�; 李明; 欧阳平凯
Original assignee: Nanjing Tech University
Current assignee: Nanjing Tech University
Priority date: 2020-10-30
Filing date: 2020-10-30
Publication date: 2022-05-17
Anticipated expiration: 2040-10-30
Also published as: CN112280265A; CN112280265B; CN113831697A

Abstract

The invention relates to the field of packaging materials, in particular to application of lignin in preparation of a degradable chemical foaming material. According to the invention, the lignin is applied to the degradable foaming packaging material, and can effectively replace degradable resin, so that the cost is reduced; the modified esterified lignin can act on other aromatic polyesters such as PBAT or PBST, so that the bonding strength between degradable resins is further improved, the performance of the material is improved, the using amount of the lignin can be further improved, and the cost is further reduced.

Description

Application of lignin in preparation of degradable chemical foaming material

Technical Field

The invention relates to the field of packaging materials, in particular to application of lignin in preparation of a degradable chemical foaming material.

Background

With the continuous development of human life, the environmental pollution is particularly serious, wherein the foam packaging material can cause serious pollution to the natural environment, and the traditional foam material substrate such as polystyrene and the like has poor performance and is not easy to recycle due to thermosetting plastics. Therefore, in recent years, the degradable foaming materials have been extensively studied, and commonly used degradable resins such as polycaprolactone PCL, polyglycolic acid PGA, polybutylene succinate PBS, polybutylene succinate adipate PBSA, polybutylene terephthalate adipate PBAT, polybutylene succinate/terephthalate PBST, polylactic acid PLA, and the like. Although the degradable foaming material can effectively solve the environmental problem, the price is extremely high, and the market can really adopt the degradable foaming material to replace the traditional foaming material, so that the problem of high price of the degradable foaming material is urgently needed to be solved.

Lignin is a well-established renewable biomass resource, widely present in almost all plant-based biomass materials, and an important component of cell walls. In the prior art, lignin is mainly derived from black liquor generated in the cooking stage of pulping and papermaking, and most of the black liquor is mainly burnt to provide energy for a pulp mill, so that the waste of lignin resources is caused. With the sustainable development and the rise of green chemical concepts, the related research on the conversion of lignin into high value-added chemicals is receiving wide attention. However, due to the characteristics of complex structure, large polydispersity, low chemical functional group content, etc., only 1% of the total lignin in the industry is converted into valuable industrial products. Therefore, finding a new utilization way of lignin and converting the lignin into high value-added chemicals or preparing high-performance materials by a material technology has become a key research point at home and abroad.

The Chinese patent application, application number 201410494397.4, discloses a degradable foam material and a preparation method thereof, wherein the degradable foam packaging material is prepared from plant fibers and degradable resin, so that the cost can be effectively reduced, and the performances such as toughness and the like can be improved; application number 201710267423.3 discloses a preparation method of a high-rate full-biodegradable material, which comprises the steps of preparing a blend of PLA and PBAT by using an internal mixer, adding an epoxy chain extender and a nucleating agent, and obtaining a polylactic acid foam material with a foaming rate of 60-80 in a physical foaming mode. However, in the prior art, plant fibers are used as a filler, and due to the structural and polarity mismatch with degradable resins, the melt strength can be greatly reduced, so that the foaming ratio and the product performance of a product are influenced; without the use of fillers, this would result in an excessively high product cost. Therefore, it is highly desirable to develop a natural biomass raw material that is low in cost and has good compatibility with degradable resins. The lignin is a thermoplastic natural aromatic polymer with glass transition temperature in nature, and can be converted into natural aromatic polyester by a proper modification mode due to a large number of benzene ring structures contained in the structure of the lignin. Has good compatibility with PBAT or PBST resin which is also aromatic polyester. Therefore, the present invention acts lignin on the degradable resin to increase the substitution amount of the resin while increasing the compatibility, thereby reducing the cost.

Disclosure of Invention

The purpose of the invention is as follows: the invention aims to solve the technical problem of providing the application of lignin in preparing degradable foam packaging materials aiming at the defects of the prior art.

In order to solve the technical problems, the invention discloses application of lignin in preparation of degradable foam packaging materials.

The lignin is any one or combination of several of alkali lignin, soda lignin, organic solvent lignin and enzymatic hydrolysis lignin, or modified lignin prepared by modifying any one of alkali lignin, soda lignin, organic solvent lignin and enzymatic hydrolysis lignin; wherein, the modification is any one or combination of more of acylation, esterification, etherification, epoxidation, phenolization, alkylation, demethylation, amination, vulcanization and unsaturated functionalization; preferably, the lignin is any one or two of esterified lignin and acylated lignin.

Wherein the particle size d50 of the lignin is 2-10 μm.

The specific modification methods of acylation, esterification, etherification, epoxidation, phenolization, alkylation, demethylation, amination, vulcanization and unsaturated functionalization are the ones in the prior art, i.e. the modification methods provided in the prior art are all applicable to the present application.

Preferably, the degradable foam packaging material further comprises the following components: a degradable resin; wherein the degradable resin is a mixture of one or two of polybutylene terephthalate-adipate (PBAT) and polybutylene succinate/terephthalate (PBST) and polylactic acid (PLA).

Further preferably, the weight part ratio of the PLA to any one or more of PBAT and PBST is 7: 3-5: 5.

Wherein, the degradable foaming packaging material also comprises the following components: a foaming agent; wherein the foaming agent is any one or a combination of more of azodicarbonamide, ammonium bicarbonate, sodium bicarbonate (sodium bicarbonate and sodium dihydrogen carbonate), 4' -oxo-diphenyl sulfonyl hydrazide OBSH, toluene sulfonyl phthalein semicarbazide and urea; preferably, the foaming agent is 4,4' -oxybis-benzenesulfonyl hydrazide OBSH.

Wherein the degradable foaming packaging material comprises the following components in parts by weight:

100 parts of degradable resin;

1-100 parts of lignin;

5-30 parts of foaming agent.

Preferably, the weight part ratio of the degradable resin to the lignin is 100 parts: 30-100 parts of a solvent; further preferably 100 parts: 30-60 parts; more preferably 100 parts: 50 parts of the raw materials.

Further preferably, the degradable foaming packaging material further comprises any one or a combination of several of a compatilizer, a filler and a nucleating agent.

Wherein the compatilizer is any one or combination of two of epoxy chain extender and isocyanate chain extender; wherein the epoxy chain extender is preferably a Basff chain extender with the model number of

ADR-4400, or ADR-4468; wherein, the isocyanate chain extender includes but is not limited to toluene diisocyanate chain extender (TDI).

Wherein the filler is any one or combination of more of calcium carbonate, calcium sulfate, starch, talcum powder, montmorillonite and wood fiber; preferably, the mesh number of the calcium carbonate and the calcium sulfate is 2000-3000 meshes; the mesh number of the wood fiber is 600-1500 meshes.

Wherein the nucleating agent is any one or the combination of more of phenyl zinc phosphate (TMC-200) and sebacic acid diphenyl dihydrazide (TMC-300).

wherein the weight parts of the compatilizer, the filler and the nucleating agent are not 0 at the same time.

Further preferably, the degradable foaming packaging material comprises the following components in parts by weight:

wherein, the weight portions of the compatilizer, the filler and the nucleating agent are not 0 at the same time.

The preparation method of the degradable foam packaging material is also within the protection scope of the invention, and comprises the following steps:

s1: according to the formula ratio, mixing the dried materials, placing the mixture in parallel double screws, carrying out high-temperature shearing at the temperature of 150-170 ℃, and carrying out extrusion pre-foaming through a microporous template of the double screws;

s2: placing the pre-foamed material in a secondary forming device at the temperature of 160-165 ℃ under the pressure of 1 multiplied by 10⁵～2×10⁵Foaming under Pa, and cooling and shaping at 30-80 deg.C.

In the step S1, the aperture of the double-screw micropore template is 0.1-0.9 mm.

Has the advantages that: compared with the prior art, the invention has the following advantages:

according to the invention, the lignin is applied to the degradable foaming packaging material, and can effectively replace degradable resin, so that the cost is reduced; the modified esterified lignin can act on other aromatic polyesters such as PBAT or PBST, so that the bonding strength between degradable resins is further improved, the performance of the material is improved, the using amount of the lignin can be further improved, and the cost is further reduced.

Detailed Description

The foregoing and/or other advantages of the invention will become more apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings.

The experimental methods described in the following examples are all conventional methods unless otherwise specified; the reagents and materials are commercially available, unless otherwise specified. In the invention, the lignin is modified by the prior art, the same modification is carried out, different modification methods have little influence on the lignin, and the following esterification, epoxidation, phenolization and acylation are common modification methods in the field.

In the following examples, the lignin used includes unmodified lignin and modified lignin, and the particle size d50 is 3 to 8 μm.

The PLA used in the following examples was NatureWorks 4032D, USA, and PBAT was Xinjiang Lantun river TH 801T.

Examples 1 and 2, comparative examples 1 and 2

The formula is as follows: the dosage of the PBAT and the lignin is shown in Table 1 according to the weight portion of 70 portions of PLA, 20 portions of OBSH and 20 portions of epoxy chain extender ADR-44003 portions.

The preparation method comprises the following steps:

s1: according to the formula ratio, mixing the dried materials, placing the mixture in parallel double screws, carrying out high-temperature shearing at the temperature of 155-165 ℃, carrying out the rotation speed of the screws at about 40rpm, and carrying out extrusion pre-foaming through a microporous template (the aperture is 0.6mm) of the double screws;

s2: placing the pre-foamed material in secondary forming equipment (a vulcanizing machine) at the temperature of 160-165 ℃ under the pressure of 1 multiplied by 10⁵～2×10⁵Foaming under Pa, and cooling and shaping at 30-50 ℃ to obtain the product.

Two important properties of the obtained foam material, namely, density and impact strength, are detected, and the detection results are shown in table 1.

TABLE 1

		Density g/cm³	Impact ofstrength/KJ/m²
				Comparative example 1	30 parts of PBAT and 0 part of lignin	0.50	4.51
Example 1	30 parts of PBAT and 20 parts of alkali lignin	0.34	4.62
				Example 2	30 parts of PBAT and 20 parts of esterified alkali lignin	0.33	6.39
Comparative example 2	30 parts of PBAT and 20 parts of corn straw fiber	0.44	5.41

As can be seen from Table 1, the PBAT can be effectively replaced by the alkali lignin in the invention, the density can be effectively reduced by replacing 20 parts of the unmodified alkali lignin in example 1, and the impact strength is also kept at a level equivalent to that in comparative example 1; in example 2, the esterified alkali lignin is adopted, so that the impact strength can be further improved and reaches 6.39KJ/m²Also, the improvement is 41.6% compared to pure PBAT. Further compared with the corn straw fiber in the comparative example 2, the density of the foaming material prepared from the alkali lignin adopted in the example 2 is lower, namely the foaming ratio is higher, and the impact strength is improved to a certain extent; compared with other plant fibers, the fiber of the inventionThe performance of the esterified lignin is better than that of other plant fibers.

Example 3

In the same manner as in example 2, only the esterified alkali lignin was replaced with the epoxidized alkali lignin, the phenolated alkali lignin and the acylated alkali lignin, respectively, and the results of the detection are shown in table 2.

TABLE 2

	Density g/cm³	Impact Strength/KJ/m²
			Alkali lignin	0.34	4.62
Esterified alkali lignin	0.33	6.39
			Epoxy alkalized lignin	0.33	4.11
Phenolated alkali lignin	0.35	4.71
			Acylated alkali lignin	0.32	6.31

As can be seen from table 2, after the lignin is modified differently, the lignin has little influence on the density of the foam material, that is, the foaming ratio has no great influence; but the impact strength of the lignin is influenced to a certain extent after different modifications are carried out on the lignin, wherein the effect after acylation and esterification is better, because the lignin can have a structure similar to PBAT after the modification through acylation and esterification, the compatibility of the lignin and the PBAT is increased, and the impact strength of the lignin is better than that of the unmodified lignin and other modified lignin.

Example 4

As in example 1, only the alkali lignin was replaced with soda lignin, organosolv lignin and enzymatic lignin, respectively, and the densities thereof were 0.36g/cm³、0.35g/cm³、0.33g/cm³(ii) a The impact strength is respectively 4.3KJ/m²、4.1KJ/m²、4.5KJ/m²The results show that lignin pretreated by different methods has no great influence on the foaming ratio and the impact strength.

Example 5

The amount ratio of the degradable resin to the lignin was changed as in example 1, and is shown in Table 3.

TABLE 3

As can be seen from table 3, the addition of lignin contributes to the improvement of the expansion ratio for the unmodified lignin, but when the amount of lignin exceeds 30 parts, the change in density is low. Meanwhile, the addition of lignin is also beneficial to the improvement of the impact strength within the use amount of 20 parts, but the impact strength is reduced when the use amount of lignin is 20 parts.

Example 6

The ratio of the amount of the degradable resin to the amount of the esterified alkali lignin was changed as in example 2, and is shown in Table 4.

TABLE 4

As can be seen from table 4, the addition of esterified lignin contributes to the increase of the foaming ratio, and the overall change tendency thereof is similar to that of unmodified alkali lignin. Meanwhile, the addition of lignin is also beneficial to improving the impact strength, but when the amount of the lignin is 50 parts, the impact strength is reduced, and compared with the unmodified lignin, the amount of the lignin can be further increased after the esterification modification.

Example 7

The amount ratio of PLA to PBAT was varied as in example 1, and is shown in Table 5.

TABLE 5

PLA	PBAT	Density g/cm³	Impact Strength/KJ/m²
				70 (example 1)	30	0.34	4.62
60	40	0.38	4.60
				50	50	0.42	4.37
40	60	0.47	4.28

As can be seen from Table 5, the density of the resulting foamed material increased with the reduction in the amount of PLA, indicating that the amount of PLA was advantageous for foaming; meanwhile, as the amount of PBAT is increased, the impact strength can also be improved.

Example 8

Just different fillers were added as in examples 1 and 2, respectively, as shown in table 6.

TABLE 6

As can be seen from table 6, in the case of adding the filler, the impact performance is still improved to a certain extent except that the calcium carbonate causes a slight increase in density and a slight decrease in foaming ratio; and when the corn stalk fiber and the esterified alkali lignin are used simultaneously, the effect is better than that of the corn stalk fiber and the unmodified lignin.

Example 9

The formula is as follows: 60 parts of PLA, 40 parts of PBST, 50 parts of acylated lignin, 5 parts of OBSH, ADR-44682 parts, 20 parts of corn fiber (d50 is 1mm) and TMC-2000.007 parts;

the preparation process comprises the following steps:

s1: according to the formula ratio, mixing the dried materials, placing the mixture in parallel double screws, carrying out high-temperature shearing at the temperature of 160-170 ℃, carrying out the rotation speed of the screws at about 45rpm, and carrying out extrusion pre-foaming through a microporous template (the aperture is 0.8mm) of the double screws;

s2: placing the pre-foamed material in secondary forming equipment (a vulcanizing machine) at the temperature of 160-165 ℃ under the pressure of 2 multiplied by 10⁵Foaming under Pa, and cooling and shaping at 30 ℃ to obtain the foam.

The resulting foam had a density of 0.31g/cm3 and an impact strength of 7.87KJ/m²。

Example 10

The formula is as follows: 50 parts of PLA, 50 parts of PBST, 50 parts of esterified lignin, 10 parts of OBSH, 20 parts of ADR-44682 parts of corn fiber (d50 is 1mm) and 2000.004 parts of TMC;

the preparation process comprises the following steps:

s1: according to the formula ratio, mixing the dried materials, placing the mixture in parallel double screws, carrying out high-temperature shearing at the temperature of 160-170 ℃, carrying out the rotation speed of the screws at about 45rpm, and carrying out extrusion pre-foaming through a microporous template (the aperture is 0.6mm) of the double screws;

s2: placing the pre-foamed material in secondary forming equipment (a vulcanizing machine) at the temperature of 160-165 ℃ under the pressure of 2 multiplied by 10⁵Foaming under Pa, and cooling and shaping at 30 ℃ to obtain the product.

The density of the resulting foamed material was 0.23g/cm³Impact strength of 6.87KJ/m²。

Comparative example 3

As in example 1, only 30 parts of PBAT were replaced by 30 parts of polycaprolactone PCL, the density of the resulting expanded material being 0.35g/cm³Impact strength of 4.14KJ/m²。

Comparative example 4:

in the same manner as in example 1, only 30 parts of PBAT were replaced with 30 parts of polycaprolactone PCL, and 20 parts of alkali lignin were replaced with 20 parts of esterified alkali lignin, and the resulting foamed material had a density of 0.35g/cm³Impact strength of 4.10KJ/m²。

It can be seen from comparative examples 3 and 4 that when a degradable resin such as PCL is used, the impact strength is not as good as PBAT and PBST, but the expansion ratio of the foam is not greatly affected; and even after the esterified lignin is adopted, the performance of the esterified lignin is not effectively improved.

The invention provides the idea and method of application of lignin in preparing degradable foamed materials, and the method and way for implementing the technical scheme are many, the above description is only a preferred embodiment of the invention, it should be noted that, for those skilled in the art, without departing from the principle of the invention, several improvements and modifications can be made, and these should be regarded as the protection scope of the invention. All the components not specified in the present embodiment can be realized by the prior art.

Claims

1. The application of lignin in preparing degradable foaming packaging materials;

wherein the lignin is alkali lignin modified by esterification and/or acylation;

wherein, the degradable foaming packaging material also comprises degradable resin; the degradable resin is a mixture of one or two of polybutylene terephthalate-adipate and polybutylene succinate/terephthalate and polylactic acid;

wherein, the degradable foaming packaging material also comprises any one or a combination of a plurality of foaming agents, compatilizers and nucleating agents;

100 parts of degradable resin;

20 parts or 30-50 parts of lignin;

5-20 parts of a foaming agent;

2-3 parts of a compatilizer;

0-0.01 part of nucleating agent;

in the degradable resin, the weight portion of any one or two of polybutylene terephthalate-adipate and polybutylene succinate/terephthalate composition and polylactic acid is 30: 70, or 40: 60, or 50: 50;

wherein the particle size d50 of the lignin is 2-10 μm.

2. The use of claim 1, wherein the foaming agent is any one or a combination of azodicarbonamide, ammonium bicarbonate, sodium bicarbonate, 4' -oxybis benzenesulfonylhydrazide, toluene sulfonphthalein semicarbazide and urea.

3. The use of claim 1, wherein the compatibilizer is one or a combination of epoxy chain extender and isocyanate chain extender.

4. The use of claim 1, wherein the nucleating agent is any one or a combination of phenyl zinc phosphate and sebacic acid diphenyl dihydrazide.

5. The use according to claim 1, wherein said degradable foamed packaging material further comprises a filler.

6. The use according to claim 5, wherein the weight ratio of the degradable resin to the filler is 100 parts: and 20 parts of the components.

7. Use according to claim 5, wherein the filler is wood fibres.

8. Use according to any one of claims 5-7, characterized in that the filler is corn stover fiber.