CN116987471A - Starch polylactic acid degradable express bag sealing adhesive and preparation method thereof - Google Patents

Abstract

The invention discloses a starch polylactic acid degradable express bag sealing adhesive and a preparation method thereof, wherein the starch polylactic acid degradable express bag sealing adhesive is prepared from the following components in percentage by weight: 1-20 parts of decaglycerol, 1-20 parts of polyethylene glycol, 10-60 parts of styrene modified polylactic acid, 10-40 parts of silane coupling agent modified terpene resin and 10-40 parts of rosin glyceride; according to the invention, the formula of the hot melt adhesive is optimized, and the degradable express bag is firmly adhered at the sealing position by the synergistic effect of the substances such as the ten polyglycerol, the polyethylene glycol, the styrene modified polylactic acid, the silane coupling agent modified terpene resin and the rosin glyceride, and can achieve the tearing effect when a consumer unpacks the degradable express bag, so that the degradable express bag has a protective effect on articles, can be degraded by microorganisms, has a protective effect on the environment, and is widely used in the market.

Description

Starch polylactic acid degradable express bag sealing adhesive and preparation method thereof

Technical Field

The invention relates to the technical field of hot melt adhesives, in particular to a starch polylactic acid degradable express bag sealing adhesive and a preparation method thereof.

Background

In the Internet age, online shopping has become an indispensable consumption mode in production and life of people, and along with the rapid development of the Internet industry, people really realize shopping without going home. Therefore, the express bags are also popular and widely appear in the field of view of consumers, and most of the express bags are made of polyolefin materials, so that the express bags cannot be biodegraded, and finally become garbage to pollute the environment, and various problems such as resource waste, environmental pollution and the like are brought.

Along with the high attention of people to environmental protection, in order to meet the requirements of environmental protection and sustainable development of green chemical industry, a novel degradable express bag such as starch/polylactic acid is available in the market, and the express bag can be automatically degraded into small molecules such as carbon dioxide and water after being discarded and enters into natural circulation, so that the environment is protected. However, the degradable express bag still has the following defects when in use: 1. the conventional sealing hot melt adhesive cannot enable the sealing part to be firmly adhered and achieve the state of tearing the express bag when the sealing part is detached, so that articles are lost or damaged due to violence when the articles are detached; 2. the conventional sealing hot melt adhesive is the same as the undegradable express bag, and can not be degraded by microorganisms, so that the conventional sealing hot melt adhesive can only be processed by adopting an incineration method during processing, thereby not only causing the waste of resources, but also causing pollution to the atmospheric environment and having the pollution effect on the environment, and the undegradable express bag and the sealing adhesive used by the same can not be really realized, so that the effect of protecting the environment is achieved.

Therefore, the development of the degradable express bag sealing adhesive which can firmly adhere the express bag sealing part and achieve the effect of tearing the express bag when being disassembled is still needed to be continued, so that the problems in the prior art are solved, and the degradable express bag is widely used in the market.

Disclosure of Invention

In order to overcome the defects of the prior art, one of the purposes of the invention is to provide the starch polylactic acid degradable express bag sealing adhesive, and the invention ensures that the sealing part of the degradable express bag is firmly adhered by optimizing the hot melt adhesive formula, can achieve the tearing effect when a consumer unpacks the bag, protects the articles, can be degraded by microorganisms, protects the environment and ensures that the degradable express bag is widely used in the market.

One of the purposes of the invention is realized by adopting the following scheme:

the starch polylactic acid degradable express bag sealing adhesive is prepared from the following components in percentage by weight: 1-20 parts of decaglycerol, 1-20 parts of polyethylene glycol, 10-60 parts of styrene modified polylactic acid, 10-40 parts of silane coupling agent modified terpene resin and 10-40 parts of rosin glyceride.

Further, the paint is prepared from the following components in percentage by weight: 4-16 parts of decaglycerol, 4-16 parts of polyethylene glycol, 35-50 parts of styrene modified polylactic acid, 15-40 parts of silane coupling agent modified terpene resin and 14-38 parts of rosin glyceride.

Further, the mass ratio of the polyethylene glycol to the decaglycerol is 1:1.

Further, the preparation method of the styrene modified polylactic acid comprises the following steps: adding the following components in a reaction kettle in a mass ratio of (90-100): and (2-3) heating the polylactic acid and the styrene to 130-150 ℃, blending for 2-4 hours, cooling, and extruding to obtain the styrene modified polylactic acid.

Further, the molecular weight of the polylactic acid is 30000-60000.

Further, the mass ratio of the polylactic acid to the styrene is 100:3, a step of; the blending temperature is 140 ℃; the blending time is 3 hours; the styrene is selected from 100-42-5 of CASNo of Jinan Yuan Xiang chemical industry Co., ltd; the polylactic acid is selected from Shanghai plastic cement Co., ltd, and the brand name of the polylactic acid is 3052D.

Further, the preparation method of the silane coupling agent modified terpene resin comprises the following steps: adding the weighed terpene resin and a platinum catalyst into a reaction kettle, heating to 120 ℃, adding a silane coupling agent, reacting for 1 hour after addition, reacting for 4-5 hours at 100 ℃, and discharging to obtain the silane coupling agent modified terpene resin.

Further, the ratio of the terpene resin to the silane coupling agent to the platinum catalyst is 100:2.5:0.1.

further, the silane coupling agent is CASNo selected from new materials, inc. of Shandong Huachen Chen: 3473-76-5 aniline methyltriethoxysilane; the terpene resin is selected from BT-TR of Puyang Kjeldahl petroleum resin Co., ltd; the platinum catalyst is CASNO which is purchased from Shanghai Sibao advanced materials Co., ltd.): 68478-92-2.

Further, the decaglycerol is decaglycerol selected from CASNo of WUHan Hua Xiangke Jieshi Biotechnology Co., ltd.: 9041-07-0; the polyethylene glycol is polyethylene glycol with molecular weight of 800 and is selected from CASNo of Jinan Xiangfeng chemical industry Co.Ltd.

The second purpose of the invention is realized by adopting the following technical scheme:

a preparation method of starch polylactic acid degradable express bag sealing glue comprises the following steps:

s1: adding the formula amount of the decaglycerol and the polyethylene glycol into a stainless steel reaction kettle, heating to 140-150 ℃ under the protection of nitrogen environment, and stirring at a speed of 40-45 r/min;

s2: adding the styrene modified polylactic acid with the formula amount into the reaction kettle of the S1, and stirring for 1-2 hours at the stirring speed of 50-60 r/min; keeping the constant temperature at 150 ℃;

s3: stopping introducing nitrogen after the reaction of the S2 is completed, adding a silane coupling agent to modify terpene resin, adding rosin glyceride after the silane coupling agent terpene resin is completely melted, and keeping the constant temperature at 150 ℃;

s4: after the rosin glyceride in the S3 is completely melted, opening a vacuum pump to vacuum, and maintaining the vacuum degree at 0.1MPA for 60min;

s5: stopping vacuumizing, cooling to 100 ℃, and discharging to obtain a product;

the starch polylactic acid degradable express bag sealing adhesive is prepared from the following components in percentage by weight: 1-20 parts of decaglycerol, 1-20 parts of polyethylene glycol, 10-60 parts of styrene modified polylactic acid, 10-40 parts of silane coupling agent modified terpene resin and 10-40 parts of rosin glyceride.

Compared with the prior art, the invention has the beneficial effects that:

1. the main components of the degradable express bag are starch and polylactic acid, and in the formula, the decaglycerol can be used as a plasticizer of the starch, so that the toughness of the bag is changed into softness; polylactic acid has certain hardness, but has small cohesive strength, and the cohesive strength can be improved by styrene modification, and the polylactic acid is soft at high temperature but has certain cohesive strength; polyethylene glycol is used as a plasticizer of styrene modified polylactic acid, so that the polyethylene glycol becomes softer at normal temperature and low temperature, and the bonding performance at low temperature is improved;

furthermore, the polyethylene glycol and the decaglycerol adopted by the invention have good compatibility, so that the whole system is transparent and is not layered, and when the proportion of the polyethylene glycol to the decaglycerol is 1:1, the tearing degree of the express bag is the best; the terpene resin has the advantages of good adhesive force, good stripping force, good heat resistance and the like, and after the terpene resin is modified by the silane coupling agent, the biocompatibility of the terpene resin can be improved, and the terpene resin can be better combined with other substances, so that the stripping force of the terpene resin is greatly improved, and the adhesive property of the terpene resin is effectively improved; the rosin glyceride has low softening point and good low-temperature performance, can be dissolved in alcohol solvents with medium and high molecular weight and terpene resins, so that the whole system has good compatibility, and the stripping force and transparency of the whole system are improved;

2. according to the invention, through the synergistic effect of the substances of the decaglycerol, the polyethylene glycol, the styrene modified polylactic acid, the silane coupling agent modified terpene resin and the rosin glyceride, the sealing part of the degradable express bag is firmly stuck, the tearing effect can be achieved when a consumer unpacks the degradable express bag, the protection effect on articles is achieved, meanwhile, the degradable express bag can be degraded by microorganisms, the protection effect on the environment is achieved, and the degradable express bag is widely used in the market.

Detailed Description

The present invention will be further described with reference to the following specific embodiments, and it should be noted that, on the premise of no conflict, new embodiments may be formed by any combination of the embodiments or technical features described below.

In the present invention, unless otherwise specified, all parts and percentages are by weight, and the equipment, materials, etc. used are commercially available or are conventional in the art. The methods in the following examples are conventional in the art unless otherwise specified.

The invention provides a starch polylactic acid degradable express bag sealing adhesive, which is prepared from the following components in percentage by weight: 1-20 parts of decaglycerol, 1-20 parts of polyethylene glycol, 10-60 parts of styrene modified polylactic acid, 10-40 parts of silane coupling agent modified terpene resin and 10-40 parts of rosin glyceride.

As a further preferable scheme, the starch polylactic acid degradable express bag sealing gum is prepared from the following components in percentage by weight: 4-16 parts of decaglycerol, 4-16 parts of polyethylene glycol, 35-50 parts of styrene modified polylactic acid, 15-40 parts of silane coupling agent modified terpene resin and 14-38 parts of rosin glyceride.

As a further preferable scheme, the starch polylactic acid degradable express bag sealing gum is prepared from the following components in percentage by weight: 8 parts of decaglycerol, 8 parts of polyethylene glycol, 45 parts of styrene modified polylactic acid, 25 parts of silane coupling agent modified terpene resin and 14 parts of rosin glyceride.

As a further preferable scheme, the mass ratio of the polyethylene glycol to the decaglycerol is 1:1.

The components of the formula of the invention are analyzed as follows:

1. decapolyglycerol (polyglycerol-10)

The decaglycerol (polyglycerol-10) is an organic compound, colorless odorless transparent viscous liquid, is dissolved in organic solvents such as water, alcohols, phenols and the like, has a molecular weight of 758, is one of main plasticizers of starch-based degradable materials, and can be automatically decomposed into small molecules such as water, carbon dioxide and the like in nature.

2. Polyethylene glycol (PEG)

Polyethylene glycol (PEG) is a high molecular polymer, is non-irritating, slightly bitter in taste, has good water solubility, and has good compatibility with many organic components. The modified polyurethane foam has excellent lubricity, moisture retention, adhesiveness and dispersibility, can be used as a softening agent, and can improve certain adhesiveness by mixing with a degradable material. The polyethylene glycol is in different states due to different molecular weights, the molecular weight is 200-600 and is liquid at normal temperature, the molecular weight is 600-1000 and is semisolid, and the molecular weight is more than 1000, and the polyethylene glycol with the molecular weight of 800 is used in the invention. In addition, the PEG-800 is also beneficial to improving the degradation speed of polylactic acid.

3. Styrene-modified polylactic acid

Polylactic acid, also called as polylactide, is a polyester polymer obtained by polymerizing lactic acid as a main raw material, and is a novel biodegradable material. Polylactic acid has good thermal stability, good biocompatibility, good glossiness and transparency, good biodegradability, and can be completely degraded by microorganisms in nature after use, and finally carbon dioxide and water are generated. Although polylactic acid has good heat resistance, the polylactic acid has high hardness and small cohesive strength, and softens at high temperature without cohesive strength, and the styrene modified polylactic acid can improve the cohesive strength of the polylactic acid, so that the polylactic acid has cohesive strength after being softened at high temperature, and the defects of high hardness and small cohesive strength of the polylactic acid are effectively overcome.

4. Silane coupling agent modified terpene resin

The terpene resin is a light yellow viscous liquid or transparent brittle solid, is easily dissolved in toluene, aliphatic hydrocarbon and the like, and is difficultly dissolved in methanol, ethanol and the like. The silane coupling agent modified terpene resin can improve the compatibility of the terpene resin in alcohols, and can greatly improve the stripping force, thereby improving the bonding strength.

5. Rosin glyceride

Rosin glycerin ester, aliased ester gum, hydrogenated gum and triglyceride, transparent liquid, flaky or pale yellow granular solid, and can be dissolved in aromatic and aliphatic and medium-high molecular alcohol solvents, terpenes, esters and the like, and has the advantages of light color, low odor, good oxidation resistance, lower softening point and good low-temperature adhesive property.

The main components of the degradable express bag are starch and polylactic acid, and the decaglycerol can be used as a plasticizer of the starch, so that the toughness of the bag is changed into softness; polylactic acid has certain hardness, but has small cohesive strength, and the cohesive strength can be improved by styrene modification, and the polylactic acid is soft at high temperature but has certain cohesive strength; polyethylene glycol is used as a plasticizer of styrene modified polylactic acid, so that the polyethylene glycol becomes softer at normal temperature and low temperature, and the bonding performance at low temperature is improved;

furthermore, the polyethylene glycol and the decaglycerol adopted by the invention have good compatibility, so the whole system is transparent and is not layered, and when the proportion of the polyethylene glycol to the decaglycerol is 1:1, the tearing degree of the express bag is the best; the terpene resin has the advantages of good adhesive force, good stripping force, good heat resistance and the like, and after the terpene resin is modified by the silane coupling agent, the biocompatibility of the terpene resin can be improved, and the terpene resin can be better combined with other substances, so that the stripping force of the terpene resin is greatly improved, and the adhesive property of the terpene resin is effectively improved; the rosin glyceride has low softening point and good low-temperature performance, can be dissolved in alcohol solvents with medium and high molecular weight and terpene resins, so that the whole system has good compatibility, and the stripping force and transparency of the whole system are improved;

according to the invention, through the synergistic effect of the substances of the decaglycerol, the polyethylene glycol, the styrene modified polylactic acid, the silane coupling agent modified terpene resin and the rosin glyceride, the sealing part of the degradable express bag can be firmly stuck, the tearing effect can be achieved when a consumer unpacks the degradable express bag, the protection effect on the articles can be achieved, meanwhile, the degradable express bag can be degraded by microorganisms, the protection effect on the environment can be achieved, and the degradable express bag can be widely used in the market.

As a further preferable scheme, the preparation method of the styrene-modified polylactic acid comprises the following steps: adding the following components in a reaction kettle in a mass ratio of (90-100): and (2-3) heating the polylactic acid and the styrene to 130-150 ℃, blending for 2-4 hours, cooling, and extruding to obtain the styrene modified polylactic acid.

As a further preferable mode, the molecular weight of the polylactic acid is 30000-60000. The invention adopts polylactic acid with molecular weight of 30000-60000, can ensure certain strength and has good biodegradability.

As a further preferable scheme, the mass ratio of the polylactic acid to the styrene is 100:3, a step of; the blending temperature is 140 ℃; the blending time is 3 hours; the styrene is selected from 100-42-5 of CASNo of Jinan Yuan Xiang chemical industry Co., ltd; the polylactic acid is selected from Shanghai plastic cement Co., ltd, and the brand name of the polylactic acid is 3052D. In the invention, the consumption of the styrene cannot be too high, and the compatibility of the blend of the styrene and the blend is influenced by the too high consumption, and the applicant finds that the mass ratio of the polylactic acid to the styrene is 100:3, blending at 140 ℃ for 3 hours or longer, and obtaining the styrene modified polylactic acid product with good quality without adding a compatilizer.

As a further preferable scheme, the preparation method of the silane coupling agent modified terpene resin is as follows: adding the weighed terpene resin and a platinum catalyst into a reaction kettle, heating to 120 ℃, adding a silane coupling agent, reacting for 1 hour after addition, reacting for 4-5 hours at 100 ℃, and discharging to obtain the silane coupling agent modified terpene resin.

As a further preferable scheme, the ratio of the terpene resin, the silane coupling agent and the platinum catalyst is 100:2.5:0.1. in this embodiment, the applicant found through a number of experiments that the ratio of the terpene resin, the silane coupling agent, and the platinum catalyst is 100:2.5:0.1, the prepared silane coupling agent modified terpene resin has optimal performance; the reason is that: as the concentration of the silane coupling agent increases, the grafting rate is in an ascending trend, but when the grafting rate reaches a certain concentration, the effect of the silane coupling agent on the grafting rate is not greatly increased, and the continuous increase of the concentration of the silane coupling agent does not further improve the performance of the silane coupling agent because the amount of monomers participating in the reaction is not changed, so that when the mass ratio of the terpene resin to the silane coupling agent is 100:2.5, the grafting rate is highest, the polarity of the product is higher, the compatibility is better, and the adhesive force and the adhesive property of the product are effectively improved. Similarly, the concentration of the platinum catalyst is increased, the grafting rate is in an ascending trend, but the concentration of the platinum catalyst is too high, the toxicity is increased, and the environment is polluted, so that when the mass ratio of the terpene resin to the silane coupling agent to the platinum catalyst is 100:2.5:0.1, the grafting rate is highest, the polarity is highest, the compatibility is best, and the adhesive force and the bonding performance are improved to the greatest extent.

As a further preferable scheme, the silane coupling agent is cas no, available from new materials, inc. In the mornings of the shandong province: 3473-76-5 aniline methyltriethoxysilane; the terpene resin is selected from BT-TR of Puyang Kjeldahl petroleum resin Co., ltd; the platinum catalyst is CASNO which is purchased from Shanghai Sibao advanced materials Co., ltd.): 68478-92-2.

As a further preferable scheme, the decapolyglycerol is decapolyglycerol selected from the group consisting of CASNo of the WU Hua Xiangke Jie Biotechnology Co., ltd.: 9041-07-0; the polyethylene glycol is polyethylene glycol with molecular weight of 800 and is selected from CASNo of Jinan Xiangfeng chemical industry Co.Ltd. PEG-800 is semisolid, has high molecular weight and better compatibility with rosin glyceride, can plasticize degradable materials, ensures certain cohesive strength, has excellent degradability, and can be automatically decomposed into small molecules such as water, carbon dioxide and the like; in addition, the PEG-800 is also beneficial to improving the degradation speed of polylactic acid.

The invention also provides a preparation method of the starch polylactic acid degradable express bag sealing adhesive, which comprises the following steps:

s1: adding the formula amount of the decaglycerol and the polyethylene glycol into a stainless steel reaction kettle, heating to 140-150 ℃ under the protection of nitrogen environment, and stirring at a speed of 40-45 r/min;

s2: adding the styrene modified polylactic acid with the formula amount into the reaction kettle of the S1, and stirring for 1-2 hours at the stirring speed of 50-60 r/min; keeping the constant temperature at 150 ℃;

s3: stopping introducing nitrogen after the reaction of the S2 is completed, adding a silane coupling agent to modify terpene resin, adding rosin glyceride after the silane coupling agent terpene resin is completely melted, and keeping the constant temperature at 150 ℃;

s4: after the rosin glyceride in the S3 is completely melted, opening a vacuum pump to vacuum, and maintaining the vacuum degree at 0.1MPA for 60min;

s5: stopping vacuumizing, cooling to 100 ℃, and discharging to obtain a product;

the starch polylactic acid degradable express bag sealing adhesive is prepared from the following components in percentage by weight: 1-20 parts of decaglycerol, 1-20 parts of polyethylene glycol, 10-60 parts of styrene modified polylactic acid, 10-40 parts of silane coupling agent modified terpene resin and 10-40 parts of rosin glyceride.

In the preparation process, the temperature of S1 cannot be too high, carbide is easily generated due to the too high temperature, and products are polluted; if the temperature is too low, polylactic acid cannot be completely melted, and the melting effect is poor, so that the product quality is affected.

In terms of the feeding sequence, firstly, adding the formula amount of the decaglycerol and the polyethylene glycol, and aiming at plastic softening the added modified polylactic acid and reducing the viscosity of the modified polylactic acid; the silane coupling agent modified terpene resin can be better combined with the added decaglycerol, polyethylene glycol and modified polylactic acid, so that the stripping force of the modified terpene resin is greatly improved, and the bonding performance is effectively improved; finally, the rosin glyceride has low softening point and good low-temperature performance, is better dissolved in terpene resin, so that the whole system has good compatibility, and the stripping force and transparency of the whole system are improved; therefore, by adopting the feeding sequence, each performance of the prepared sealing glue can achieve better effect.

The starch polylactic acid degradable express bag sealing adhesive prepared by the invention is illustrated in the following specific examples. The raw materials, equipment, etc. used in the following examples are available in a purchase manner except for special restrictions.

Examples 1 to 5 and comparative examples 1 to 11

The raw materials were weighed according to the proportions shown in Table 1, and the products were prepared according to the procedures shown in examples 1 to 5, specifically shown in Table 1:

TABLE 1 raw material proportion Table for examples 1-5 and comparative examples 1-11

Unless otherwise specified, the above-described raw materials were used consistently in order to show comparability of the test effect. The decaglycerol is decaglycerol selected from the CASNo of the WU Hua Xiangke Jie Biotechnology Co., ltd.: 9041-07-0; the polyethylene glycol is polyethylene glycol with molecular weight of 800 and is selected from CASNo of Jinan Xiangfeng chemical industry Co.Ltd. The styrene is selected from 100-42-5 of CASNo of Jinan Yuan Xiang chemical industry Co., ltd; the polylactic acid is selected from Shanghai plastic cement Co., ltd, and the brand name of the polylactic acid is 3052D. The silane coupling agent is CASNo selected from new materials in Shandong Huachen of China: 3473-76-5 aniline methyltriethoxysilane; the terpene resin is selected from BT-TR of Puyang Kjeldahl petroleum resin Co., ltd; the platinum catalyst is CASNo which is purchased from Shanghai Sibao advanced materials Co., ltd.): 68478-92-2.

Wherein, taking example 3 as a reference, the polyethylene glycol component is absent in comparative example 1, and other preparation parameters are the same as example 3; comparative example 2 lacks a decaglycerol component, and other preparation parameters are the same as in example 3, comparative example 3 lacks a rosin glyceride component, and other preparation parameters are the same as in example 3; comparative example 4 lacks a silane coupling agent modified terpene resin component, and other preparation parameters are the same as example 3; comparative example 5 lacks a styrene-modified polylactic acid component, and other preparation parameters are the same as example 3;

in the preparation process of the styrene-modified polylactic acid in comparative example 6, polylactic acid with molecular weight of 200000 is selected, and the mass ratio of polylactic acid to styrene and other preparation parameters are the same as those in example 3;

in the preparation process of the styrene-modified polylactic acid in the comparative example 7, the mass ratio of the polylactic acid to the styrene is 100:13; other preparation parameters were the same as in example 3;

in the preparation process of the silane coupling agent modified terpene resin in comparative example 8, the ratio of the terpene resin, the silane coupling agent and the platinum catalyst is 100:8:0.1; other preparation parameters were the same as in example 3;

the polyethylene glycol in comparative example 9 is PEG-300 with molecular weight of 300; other preparation parameters were the same as in example 3;

comparative example 10 uses polylactic acid not modified with styrene instead of the styrene-modified polylactic acid of example 3, and other preparation parameters are the same as example 3;

in comparative example 11, the terpene resin not modified with the silane coupling agent was used instead of the silane coupling agent-modified terpene resin of example 3, and other preparation parameters were the same as in example 3.

Comparative example 12

The common non-degradable sealing gum is prepared from naphthenic oil, antioxidant, SIS, SSBR, carbon five petroleum resin and carbon five/carbon nine copolymerized petroleum resin and is produced by a certain manufacturer in China.

Preparation method

The preparation method of the sealing compound of the examples 1-5 and the comparative examples 1-11 comprises the following steps:

s1: adding the formula amount of the decaglycerol and the polyethylene glycol into a stainless steel reaction kettle, heating to 150 ℃ under the protection of nitrogen environment, and stirring at a speed of 40 revolutions per minute;

s2: adding the formula amount of the styrene modified polylactic acid into the reaction kettle of the S1, and stirring for 1-2 hours at a stirring speed of 60 r/min; keeping the constant temperature at 150 ℃;

s3: stopping introducing nitrogen after the reaction of the S2 is completed, adding a silane coupling agent to modify terpene resin, adding rosin glyceride after the silane coupling agent terpene resin is completely melted, and keeping the constant temperature at 150 ℃;

s4: after the rosin glyceride in the S3 is completely melted, opening a vacuum pump to vacuum, and maintaining the vacuum degree at 0.1MPA for 60min;

s5: stopping vacuumizing, cooling to 100 ℃, and discharging to obtain the product.

The preparation method of the styrene modified polylactic acid comprises the following steps: adding polylactic acid and styrene with the mass ratio of 100:3 into a reaction kettle, heating to 140 ℃, and blending for 3 hours;

the preparation method of the silane coupling agent modified terpene resin comprises the following steps: adding a weighed terpene resin and a platinum catalyst into a reaction kettle, heating to 120 ℃, and adding a silane coupling agent, wherein the mass ratio of the terpene resin to the silane coupling agent to the platinum catalyst is 100:2.5:0.1, wherein the reaction is carried out for 1 hour after the addition, then for 4 hours at 100 ℃, and discharging.

Effect evaluation and Performance detection

The sealer properties of examples 1-5 and comparative examples 1-12 were tested, and the test items and results are shown in tables 2-3.

The detection method comprises the following steps:

1. peel strength and annular primary adhesion test method

180℃peel strength was tested according to the specifications of the national standard GB/T2792-2014 and loop tack was tested according to the specifications of the national standard GB/T31125-2014. Coating the prepared sealing adhesive on the surface of a high-transparency PET film with the thickness of 30 micrometers by using a film coater, attaching a release film, standing for 24 hours at room temperature, and testing 180-degree peel strength and annular primary adhesion; the results are recorded in N/inch.

2. Express bag sealing part tearing test method

The same type of degradable express bags are selected, the sealing glue of each embodiment is used for sealing the sealing position of the degradable express bags in a melting and knife coating mode, and the tearing effect of the sealing glue when the sealing is torn is observed and recorded, and the specific test results are shown in the table 2 below.

The heavy tearing is that the whole adhesive stuck on the express bag can tear the express bag completely; the moderate tearing is that the whole adhesive stuck on the express bag can partially tear the express bag; the slight tearing is that the whole face glue on the express bag is less part can tear the express bag.

3. Degradation weightlessness rate test method

Degradation weight loss test the biodegradability of B in the European Union compost degradation plastics Standard EN13432, requirements for tests and final evaluation of packages recovered by composting and biological decomposition, specifies that the degradable compost material must be converted to carbon dioxide, water and minerals over 90% in 6 months under aerobic composting conditions.

The sealing compound of each example and comparative example was tested for composting.

The peel strength and loop tack performance test results are shown in table 2:

table 2: summary of sealer test data for examples 1-5 and comparative examples 1-12

From the above table 2 and the analysis of the formulation, it can be seen from the test data of examples 1 to 3 that the polyethylene glycol and the decaglycerol adopted by the invention have good compatibility, the mixed use of the decaglycerol and the polyethylene glycol can play a role in synergy, and the polyethylene glycol is used as a plasticizer of the styrene modified polylactic acid, so that the polyethylene glycol becomes softer at normal temperature and low temperature, and the bonding performance at low temperature is improved; the polyethylene glycol needs to plasticize the modified polylactic acid, and the polarity, the peel strength and the wettability of the plasticized modified polylactic acid on the express bag are obvious compared with those of the ten polyglycerols, so that in the embodiment 1-2, the low-temperature adhesive property of the prepared sealing glue is changed along with the different dosage of the polyethylene glycol.

Further, the applicant found through a large number of experiments that the synergy is optimal when the dosage ratio of polyethylene glycol to decaglycerol is 1:1. The sealant prepared as in example 3 was excellent in each property, and the peel strength at-10℃was greater than 30 in each of the peel strength at-10℃and the peel strength at-20℃was greater than 30 in each of the peel strength at-50℃and the peel strength at-50℃were greater than 30 in each of the peel strength at-N/inch; and can be completely torn (severe); the degradable express bag can be firmly stuck at the sealing part, and can achieve the tearing effect when the consumer unpacks the bag, thereby protecting the articles.

The amount of the modified terpene resin and the rosin glyceride of the styrene modified polylactic acid and the silane coupling agent is unchanged, the amount of the decaglycerol of the embodiment 1 is lower than that of the polyethylene glycol, and the amount of the decaglycerol of the embodiment 2 is higher than that of the polyethylene glycol, but the prepared sealing adhesive has obvious differences from the sealing adhesive prepared in the embodiment 3 in performances of-10 ℃ peel strength (N/inch), -10 ℃ tear degree, 20 ℃ peel strength (N/inch), 20 ℃ tear degree, 50 ℃ peel strength (N/inch), 50 ℃ tear degree and the like.

The decaglycerol and the polyethylene glycol complement each other and cooperate with each other: compared with example 3, in comparative example 1, polylactic acid in the express bag cannot be wetted and softened due to the lack of polyethylene glycol, and meanwhile, the compatibility of the whole system is reduced, so that even if the dosage of the decaglycerol is increased, the adhesive property of the prepared seal gum is reduced; in comparative example 2, the lack of the decaglycerol prevents the starch in the express bag from being wetted, which results in the inability of the express bag to be wetted, and thus reduces the adhesive property.

Moreover, the sealing adhesive has excellent mechanical properties, decaglycerol, polyethylene glycol and other components: the synergy of the styrene modified polylactic acid, the silane coupling agent modified terpene resin and the rosin glyceride is also inseparable: from the test data of example 3 and comparative example 3, it is understood that the low-temperature adhesive property is lowered due to the lack of rosin glyceride in comparative example 3, and the compatibility of the silane coupling agent modified terpene resin is lowered, resulting in lowering the overall adhesive property; as is clear from the data of example 3 and comparative example 4, in comparative example 4, the peel strength of the whole system is decreased linearly due to the lack of the silane coupling agent modified terpene resin, and the adhesion thereof is greatly reduced; from the data of example 3 and comparative example 5, it is understood that the absence of the styrene-modified polylactic acid component of comparative example 5 also caused a linear decrease in peel strength of the entire system, greatly reducing its adhesive strength.

In comparative example 6, polylactic acid with high molecular weight was selected as a styrene-modified polylactic acid reaction monomer, and the strength and the performance of the prepared sealer were greatly different from those of example 3, compared with polylactic acid with low molecular weight.

The use amount ratio of the styrene is increased in the comparative example 7, the blending effect with the polylactic acid is affected to a certain extent, and the prepared sealing compound has the performance which is greatly different from that of the example 3.

In comparative example 8, the proportion of the silane coupling agent is increased, but the grafting rate is not greatly influenced, and the performance of the sealing compound prepared subsequently is not improved.

In comparative example 9, low molecular weight PEG-300 was selected, which had a lower compatibility with other materials than in example 3, and the adhesive properties of the sealer prepared were greatly reduced.

As can be seen from the data of example 3 and comparative example 10, the styrene-modified polylactic acid effectively improved the cohesive strength of the polylactic acid at high temperature, so that it still reached a state of severe tearing for the degradable express bag at high temperature.

As is clear from the data of example 3 and comparative example 11, the silane coupling agent modified terpene resin improved the compatibility of the terpene resin and further improved the peel strength as compared with the unmodified terpene resin.

As can be seen from the data of comparative example 12, the sealing glue of the non-degradable express bag cannot be firmly adhered to the degradable express bag, and the tearing effect cannot be achieved.

The test results of the degradation weight loss rate test items are shown in table 3:

table 3: results of the test for the degradation weight loss ratio of sealer of examples 1 to 5 and comparative examples 1 to 12

The starch/polylactic acid degradable express bag sealing adhesive prepared by the method can be degraded in different time periods within 180 days, the highest degradation rate reaches 97.4% in 180 days, and the degradation rate of the non-degradable express bag sealing adhesive is 0.

According to the invention, through the synergistic effect of the substances of the ten polyglycerols, the polyethylene glycol, the styrene modified polylactic acid, the silane coupling agent modified terpene resin and the rosin glyceride, the sealing part of the degradable express bag can be firmly adhered, the tearing effect can be achieved when a consumer unpacks the degradable express bag, the protective effect on articles can be achieved, meanwhile, the degradable express bag can be degraded by microorganisms, the protective effect on the environment can be achieved, and the degradable express bag can be widely used in the market.

The above embodiments are only preferred embodiments of the present invention, and the scope of the present invention is not limited thereto, but any insubstantial changes and substitutions made by those skilled in the art on the basis of the present invention are intended to be within the scope of the present invention as claimed.

Claims (10)

1. The starch polylactic acid degradable express bag sealing adhesive is characterized by being prepared from the following components in percentage by weight: 1-20 parts of decaglycerol, 1-20 parts of polyethylene glycol, 10-60 parts of styrene modified polylactic acid, 10-40 parts of silane coupling agent modified terpene resin and 10-40 parts of rosin glyceride.

2. The starch polylactic acid degradable express bag sealing gum according to claim 1, which is characterized by being prepared from the following components in percentage by weight: 4-16 parts of decaglycerol, 4-16 parts of polyethylene glycol, 35-50 parts of styrene modified polylactic acid, 15-40 parts of silane coupling agent modified terpene resin and 14-38 parts of rosin glyceride.

3. The starch polylactic acid degradable express delivery bag sealing gum according to claim 1 or 2, wherein the mass ratio of polyethylene glycol to decaglycerol is 1:1.

4. The starch polylactic acid degradable express bag sealing gum according to claim 1 or 2, wherein the preparation method of the styrene modified polylactic acid is as follows: adding the following components in a reaction kettle in a mass ratio of (90-100): and (2-3) heating the polylactic acid and the styrene to 130-150 ℃, blending for 2-4 hours, cooling, and extruding to obtain the styrene modified polylactic acid.

5. The starch polylactic acid degradable express delivery bag sealing gum according to claim 4, wherein the mass ratio of polylactic acid to styrene is 100:3, a step of; the blending temperature is 140 ℃; the blending time is 3 hours; the styrene is selected from 100-42-5 of CASNo of Jinan Yuan Xiang chemical industry Co., ltd; the polylactic acid is selected from Shanghai plastic cement Co., ltd, and the brand name of the polylactic acid is 3052D.

6. The starch polylactic acid degradable express bag sealing gum according to claim 1 or 2, wherein the preparation method of the silane coupling agent modified terpene resin is as follows: adding the weighed terpene resin and a platinum catalyst into a reaction kettle, heating to 120 ℃, adding a silane coupling agent, reacting for 1 hour after addition, reacting for 4-5 hours at 100 ℃, and discharging to obtain the silane coupling agent modified terpene resin.

7. The starch polylactic acid degradable express bag sealer as defined in claim 6, wherein the ratio of terpene resin, silane coupling agent and platinum catalyst is 100:2.5:0.1.

8. the starch polylactic acid degradable express delivery bag sealer of claim 6, wherein the silane coupling agent is selected from the group consisting of cas No. available from new materials, inc. In eastern mornings: 3473-76-5 aniline methyltriethoxysilane; the terpene resin is selected from BT-TR of Puyang Kjeldahl petroleum resin Co., ltd; the platinum catalyst is CASNo which is purchased from Shanghai Sibao advanced materials Co., ltd.): 68478-92-2.

9. The starch polylactic acid degradable express delivery bag sealer as claimed in claim 1 or 2, wherein the decaglycerol is selected from the group consisting of kanno, available from the bio-technology company of wuhan Hua Xiangke: 9041-07-0 decaglycerol; the polyethylene glycol is polyethylene glycol with molecular weight of 800 and is selected from CASNo of Jinan Xiangfeng chemical industry Co.Ltd.

10. A method for preparing the starch polylactic acid degradable express bag sealing gum according to any one of claims 1 to 9, which is characterized by comprising the following steps:

s1: adding the formula amount of the decaglycerol and the polyethylene glycol into a stainless steel reaction kettle, heating to 140-150 ℃ under the protection of nitrogen environment, and stirring at a speed of 40-45 r/min;

s2: adding the styrene modified polylactic acid with the formula amount into the reaction kettle of the S1, and stirring for 1-2 hours at the stirring speed of 50-60 r/min; keeping the constant temperature at 150 ℃;

s3: stopping introducing nitrogen after the reaction of the S2 is completed, adding a silane coupling agent to modify terpene resin, adding rosin glyceride after the silane coupling agent terpene resin is completely melted, and keeping the constant temperature at 150 ℃;

s4: after the rosin glyceride in the S3 is completely melted, opening a vacuum pump to vacuum, and maintaining the vacuum degree at 0.1MPA for 60min;

s5: stopping vacuumizing, cooling to 100 ℃, and discharging to obtain a product;

the starch polylactic acid degradable express bag sealing adhesive is prepared from the following components in percentage by weight: 1-20 parts of decaglycerol, 1-20 parts of polyethylene glycol, 10-60 parts of styrene modified polylactic acid, 10-40 parts of silane coupling agent modified terpene resin and 10-40 parts of rosin glyceride.