An atmospheric pressure starch foaming glue and its preparation method and use method

Abstract

The present application relates to the technical field of cushion packaging materials (IPC classification number C08L3 / 02), and particularly relates to normal-pressure starch foaming glue and a preparation method and use method thereof, the preparation raw materials of the glue include A material, B material, foaming agent, uniform foaming agent, foaming stabilizer, the starch glue prepared by the present application has the characteristics of normal-pressure foaming in addition to the role of adhesive material, the volume can be expanded by 20-50 times under microwave heating, realizing the conversion from an adhesive material to a cushioning protective material, the foaming glue is used in combination with a foaming film, small volume winding can be realized, storage is convenient when not in use, the land area is small, and the foaming glue can be heated and foamed in time when used, thereby reducing the cost of transportation and storage of enterprises.

Description

Technical Field

[0001] This invention relates to the field of cushioning packaging materials technology (IPC classification number C08L3 / 02), and more particularly to a normal pressure starch foaming adhesive and its preparation and application methods. Background Technology

[0002] The foaming process of starch materials can be divided into two types. One is heating foaming, which involves rapidly heating the material under normal pressure to vaporize and evaporate the water in it, thereby forming a porous structure in the starch material. The other is depressurization foaming, which involves heating the material under a certain pressure to make the water in the material become a superheated liquid, and then rapidly releasing the external pressure to cause the superheated water in it to vaporize and evaporate, thereby foaming the starch material.

[0003] Chinese patent CN110790985B discloses a starch foam material and its preparation method, which achieves good foaming effect by increasing the air pressure in the molding cavity of the molding die to 150KPa~300KPa. Chinese patent CN109608701A discloses a thermoplastic starch-based foam material and its preparation method, which uses depressurization for supercritical foaming. However, pressurized foaming methods have several drawbacks. Firstly, the pressurization equipment is large and expensive. Secondly, the resulting foam material is bulky, occupying storage space, leading to extended shelf life and reduced enterprise capacity and efficiency.

[0004] Developing an adhesive that can foam at room temperature and instantly has great application potential. Summary of the Invention

[0005] The first aspect of the present invention provides a normal pressure starch foaming adhesive, wherein the raw materials for preparing the adhesive include component A, component B, foaming agent, foam leveling agent, and foam stabilizer, and the weight ratio of component A to component B is (2-5):(6-10).

[0006] Furthermore, the weight ratio of material A to material B is (2-4):(6-8), preferably (2-4):(6-8), and more preferably 3:7.

[0007] In some embodiments, the raw materials for preparing material A include: starch, gelatinizing agent, and water.

[0008] By weight, the raw materials for preparing material A include: 15-30 parts starch, 3-8 parts gelatinizing agent, and 50-100 parts water.

[0009] In some embodiments, the raw materials for preparing material B include: starch, crosslinking agent, plasticizer, and water.

[0010] By weight, the raw materials for preparing material B include: 25-40 parts starch, 0.1-0.3 parts crosslinking agent, 8-10 parts plasticizer, and 20-30 parts water.

[0011] The present invention does not impose any special limitation on the gelatinizing agent, which may be selected from, but is not limited to, at least one of sodium hydroxide, potassium hydroxide, and barium hydroxide. In the embodiments of the present invention, the gelatinizing agent is an aqueous solution of sodium hydroxide (30 wt%).

[0012] This invention does not impose any special limitations on the crosslinking agent, which can be selected from, but is not limited to, conventional crosslinking agents in the art such as sodium tetraborate decahydrate, isophorone diisocyanate, and trimethylolpropane. In the embodiments of this invention, the gelatinizing agent is sodium tetraborate decahydrate.

[0013] This invention does not impose any special limitations on plasticizers, which can be selected from, but are not limited to, conventional plasticizers in the art such as tributyl citrate, glycerol, ethanol and citric acid. In this embodiment of the invention, the plasticizer is tributyl citrate.

[0014] In some embodiments, the starch has a linear content of 70-73%, an acidity ≤1.5°T, and an ash content ≤0.1%.

[0015] The amylose content directly affects the properties of starch; the higher the amylose content, the greater the impact on starch gelatinization performance. The applicant found that selecting starch with an amylose content of 70-73%, acidity ≤1.5°T, and ash content ≤0.1% can increase the expansion rate of foaming adhesive, allowing it to expand 20-50 times its original volume under microwave heating, resulting in excellent foaming effect.

[0016] In some embodiments, the starch includes at least one of corn starch, tapioca starch, wheat starch, potato starch, sweet potato starch, legume starch, and rice starch.

[0017] Furthermore, the starch described in this invention is all corn starch, purchased from Quanyinxiangyu (Beijing) Biotechnology Co., Ltd., model number HI-70.

[0018] In some embodiments, the foam leveling agent includes at least one of polyether-modified silicone oil, Tween 20, Tween 40, Tween 60, Tween 61, Tween 80, Tween 81, Tween 85, bis-(γ-triethoxysilylpropyl)tetrasulfide, γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, vinyltriethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane.

[0019] To control the uniformity of foam density under normal pressure, the foam leveling agent is a polyether-modified silicone oil, specifically Evonik TEGOSTAB rigid foam silicone oil, with a density of 1.01-1.03 g / cm³. 3The dynamic viscosity is 800-1200 mPa·s. Compared with traditional silicone oils, this polyether-modified silicone oil contains both hydrophobic and hydrophilic groups, which can reduce surface tension in the system, prevent excessively large bubble coalescence, and avoid uneven pore size.

[0020] In some embodiments, the foam stabilizer includes at least one of 1,2-benzisothiazolin-3-one, calcium stearate, triethanolamine, dodecanol, and polyacrylamide.

[0021] The applicant discovered that, under normal pressure, adding a certain amount of foam stabilizer, especially 1,2-benzisothiazolin-3-one (CAS: 2634-33-5), can maintain the stability of the foam under high foam expansion rate, and the foamed material has excellent mechanical properties.

[0022] In some embodiments, the foaming agent comprises ADC foaming agent, sodium bicarbonate, and silica in a weight ratio of (3-6):(2-5):(0.5-1), preferably (4-6):(2-4):(0.7-1), and more preferably 5:3:0.8. The ADC foaming agent is preferably sourced from Jieheng New Materials and is in the form of a white powder.

[0023] The applicant discovered during their research that a mixture of ADC foaming agent, sodium bicarbonate, and silica in a weight ratio of (3-6):(2-5):(0.5-1) enabled the adhesive to foam under normal pressure, with a foaming effect comparable to traditional high-pressure foaming. The reason for this is speculated to be the strong compatibility of the specific foaming agent with high amylose content starch, resulting in a high internal potential energy within the adhesive system, allowing foaming to occur at room temperature. Further investigation revealed that the foaming effect was optimal when the silica was ultrafine fumed silica, especially at the submicron level.

[0024] The preferred type of silica is NanOsil ASD, purchased from Xingbeida Chemical. The surface of this silica has been modified by laser irradiation to make it a special fumed silica with hydrophilic and oleophilic properties.

[0025] In some embodiments, the viscosity of the atmospheric pressure starch foam adhesive is 10,000-20,000 Pa·s.

[0026] A second aspect of the present invention provides a method for preparing a normal-pressure starch foaming adhesive, the method comprising:

[0027] S1. Preparation of Material A: Add starch to water while stirring, continue adding gelatinizing agent, stir and keep warm to obtain Material A;

[0028] S2. Preparation of Material B: Starch, crosslinking agent, and plasticizer are added to water by stirring to obtain Material B;

[0029] S3. Add component A to component B by weight ratio, mix well, then add foaming agent, foam leveling agent, and foam stabilizer, and mix evenly to obtain atmospheric pressure starch foaming adhesive.

[0030] Furthermore, in step S3, material A is added to material B by weight and stirred until a mixture is obtained. 8-10 parts of foaming agent, 1-3 parts of foam equalizer, and 0.05-0.2 parts of foam stabilizer are added to every 100 parts of the mixture. After stirring evenly, atmospheric pressure starch foaming adhesive is obtained.

[0031] The third aspect of the present invention provides a method for using atmospheric pressure starch foaming adhesive, wherein the atmospheric pressure starch foaming adhesive is coated in the interlayer of two foaming films, the foaming films are sealed around the perimeter, and the semi-finished product is rolled up. When in use, the semi-finished product is heated under atmospheric pressure to achieve foaming.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. In addition to serving as an adhesive material, the starch adhesive prepared by this invention also has the characteristic of being able to foam under normal pressure. Its volume can expand by 20-50 times when heated by microwaves, thus realizing the transformation from an adhesive material to a buffer and protective material.

[0034] 2. Traditional starch foaming materials are generally in granular form, requiring high-pressure plasticization in a screw and sudden pressure release in a mold to cause internal gas expansion, thus causing the material to expand. Foaming at room temperature is impossible. This invention completely eliminates the need for expensive foaming equipment and large-scale foaming spaces required for existing starch material foaming, achieving expansion within 0.15m... 2 Foaming can be achieved within the range of desktop foaming equipment.

[0035] 3. The foaming adhesive of the present invention, when used in conjunction with the foaming film, can achieve small-volume rolling, convenient storage when not in use, small footprint, and instant heating and foaming when in use, thereby reducing transportation and storage costs for enterprises.

[0036] 4. The foaming adhesive of this invention produces dense and stable foam after foaming at room temperature, and the resulting cushioning material has good mechanical properties and can be widely used as a multifunctional cushioning product.

[0037] 5. This invention is the first material in the prior art that can achieve instant foaming, and it has extremely high application prospects. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the electromagnetic microwave foaming film-making machine used in performance testing. Detailed Implementation

[0039] Example 1

[0040] The first aspect of this embodiment provides a normal-pressure starch foaming adhesive, wherein the raw materials for preparing the adhesive include component A, component B, foaming agent, foam leveling agent, and foam stabilizer, and the weight ratio of component A to component B is 3:7.

[0041] By weight, the raw materials for preparing material A include: 20 parts starch, 5 parts gelatinizing agent, and 80 parts water.

[0042] By weight, the raw materials for preparing material B include: 35 parts starch, 0.2 parts crosslinking agent, 9.8 parts plasticizer, and 25 parts water.

[0043] All starches mentioned are corn starches with a linear content of 70-73%, an acidity of ≤1.5°T, and an ash content of ≤0.1%. They were purchased from Quanyin Xiangyu (Beijing) Biotechnology Co., Ltd., and the model number is HI-70.

[0044] The foaming agent is ADC foaming agent, sodium bicarbonate, and silica, in a weight ratio of 5:3:0.8. The silica is of type NanOsil ASD.

[0045] The foam leveling agent is polyether-modified silicone oil with a density of 1.01-1.03 g / cm³. 3 Dynamic viscosity 800-1200 mPa·s.

[0046] The foam stabilizer is 1,2-benzisothiazolin-3-one.

[0047] The second aspect of this embodiment provides a method for preparing a normal-pressure starch foaming adhesive, the preparation method comprising:

[0048] S1. Preparation of Material A: Add starch to water at 60℃ and continue to add gelatinizing agent, stir and keep warm at 60℃ for 1 hour to obtain Material A;

[0049] S2. Preparation of Material B: Starch, crosslinking agent, and plasticizer are added to water at 35°C with stirring to obtain Material B;

[0050] S3. Add component A to component B by weight ratio and mix well to obtain a mixture. Add 8.8 parts foaming agent, 2 parts foam leveling agent, and 0.1 parts foam stabilizer to every 100 parts of the mixture. After mixing evenly, obtain atmospheric pressure starch foaming adhesive.

[0051] The third aspect of this embodiment provides a method for using atmospheric pressure starch foaming adhesive. The atmospheric pressure starch foaming adhesive is coated between two foaming films, the foaming films are sealed around the edges, and then rolled up to obtain a semi-finished product. When using the semi-finished product, it can be foamed by heating it under atmospheric pressure.

[0052] Example 2

[0053] The first aspect of this embodiment provides an atmospheric pressure starch foaming adhesive, which is implemented in the same way as in embodiment 1, except that the weight ratio of component A to component B is 2:8.

[0054] By weight, the raw materials for preparing material A include: 15 parts starch, 3 parts gelatinizing agent, and 50 parts water.

[0055] By weight, the raw materials for preparing material B include: 25 parts starch, 0.1 parts crosslinking agent, 8 parts plasticizer, and 20 parts water.

[0056] The foaming agent is ADC foaming agent, sodium bicarbonate, and silicon dioxide in a weight ratio of 3:2:0.5.

[0057] The second aspect of this embodiment provides a method for preparing a normal pressure starch foaming adhesive, wherein 8 parts of foaming agent, 1 part of foam leveling agent, and 0.05 parts of foam stabilizer are added to every 100 parts of mixture.

[0058] The third aspect of this embodiment provides a method for using a normal pressure starch foaming adhesive, the specific implementation of which is the same as in Embodiment 1.

[0059] Example 3

[0060] The first aspect of this embodiment provides a normal-pressure starch foaming adhesive, with the specific implementation method being the same as in Embodiment 1, except that the weight ratio of component A to component B is 4:6.

[0061] By weight, the raw materials for preparing material A include: 30 parts starch, 8 parts gelatinizing agent, and 100 parts water.

[0062] By weight, the raw materials for preparing material B include: 40 parts starch, 0.3 parts crosslinking agent, 10 parts plasticizer, and 30 parts water.

[0063] The foaming agent is ADC foaming agent, sodium bicarbonate, and silicon dioxide in a weight ratio of 6:5:1.

[0064] The second aspect of this embodiment provides a method for preparing a normal pressure starch foaming adhesive, wherein 10 parts of foaming agent, 3 parts of foam leveling agent, and 0.2 parts of foam stabilizer are added to every 100 parts of mixture.

[0065] The third aspect of this embodiment provides a method for using a normal pressure starch foaming adhesive, the specific implementation of which is the same as in Embodiment 1.

[0066] Comparative Example 1

[0067] The first aspect of this comparative example provides an atmospheric pressure starch foaming adhesive, which is implemented in the same way as in Example 1, except that the weight ratio of component A to component B is 5:5.

[0068] The second aspect of this comparative example provides a method for preparing a normal-pressure starch foaming adhesive. The specific implementation method is the same as in Example 1.

[0069] The third aspect of this comparative example provides a method for using a normal-pressure starch foaming adhesive, with the specific implementation method being the same as in Example 1.

[0070] Comparative Example 2

[0071] The first aspect of this comparative example provides an atmospheric pressure starch foaming adhesive, which is implemented in the same way as in Example 1, except that the foaming agent is ADC foaming agent and sodium bicarbonate in a weight ratio of 5:3.

[0072] The second aspect of this comparative example provides a method for preparing a normal-pressure starch foaming adhesive. The specific implementation method is the same as in Example 1.

[0073] The third aspect of this comparative example provides a method for using a normal-pressure starch foaming adhesive, with the specific implementation method being the same as in Example 1.

[0074] Comparative Example 3

[0075] The first aspect of this comparative example provides an atmospheric pressure starch foaming adhesive, which is implemented in the same way as in Example 1, except that the starch is corn starch with a linear content of 55-58%, purchased from Quanyinxiangyu (Beijing) Biotechnology Co., Ltd., model number HI-55.

[0076] The second aspect of this comparative example provides a method for preparing a normal-pressure starch foaming adhesive. The specific implementation method is the same as in Example 1.

[0077] The third aspect of this comparative example provides a method for using a normal-pressure starch foaming adhesive, with the specific implementation method being the same as in Example 1.

[0078] Comparative Example 4

[0079] The first aspect of this comparative example provides an atmospheric pressure starch foaming adhesive, which is implemented in the same way as in Example 1, except that the foaming agent is 0 parts.

[0080] The second aspect of this comparative example provides a method for preparing a normal-pressure starch foaming adhesive. The specific implementation method is the same as in Example 1.

[0081] The third aspect of this comparative example provides a method for using a normal-pressure starch foaming adhesive, with the specific implementation method being the same as in Example 1.

[0082] Performance testing

[0083] The atmospheric pressure starch foaming adhesive prepared in the above examples and comparative examples was coated onto a piece of foam film with a coating weight of 100g. Then, another piece of foam film was placed on top of it, and the four sides were heat-sealed. An electromagnetic microwave foaming film feeding machine (see structure) was used. Figure 1 The foaming process is carried out using a microwave output power of 1000W, a microwave frequency of 2.45GHz, and a heating time of 10S.

[0084] The foaming film and electromagnetic microwave foaming film feeding machine mentioned above are both from Xiamen Aimeisen New Material Technology Co., Ltd. The principle of the structural components is as follows: Needle guide rollers: Their main function is to puncture the film on both sides of the roll, allowing the internal foaming liquid to absorb external air during the foaming process, causing the film to expand and preventing shrinkage of the starch adhesive foamed film. Electromagnetic microwave emitting plate and metal reflector plate: Before the film passes through these two, the resonance effect of the electromagnetic microwave waves causes the water in the foamed starch adhesive to heat up and evaporate rapidly. The ADC foaming agent in the foamed starch adhesive quickly generates gas, forming uniform pores inside the starch adhesive. The foam expands 20-50 times, with a microwave output power between 700W and 1500W and a microwave frequency of 2.45GHz. The film spends 10-20 seconds in the electromagnetic microwave heating zone. Discharge guide rollers: These mainly serve to pull the material out and flatten uneven areas of the foamed starch adhesive during the foaming process. The gap between the discharge guide rollers should not be between 1-5mm and can be adjusted according to the actual product.

[0085] After the foamed roll film is foamed, customers only need to select several overlapping units to wrap the product according to its size.

[0086] The foamed film was subjected to the following performance tests after foaming.

[0087] Foaming expansion rate test method: ASTM D3575 tests the foaming density of the film and calculates the expansion ratio. Foaming expansion rate = solution density / foam density.

[0088] Solution density = solution weight / measuring cup volume reading.

[0089] Cut the foam into a flat rectangular prism using a saw. The density of the foam is equal to the weight of the foam divided by its volume.

[0090] Viscosity test method: GB / T 10247-2008 Rotary viscometer, viscosity unit cSt.

[0091] Maximum creep test method: GBT 14745-1993.

[0092] Permanent deformation: GBT 15718-2008.

[0093] Uniformity: The range of bubble diameters is as follows; the larger the range, the worse the uniformity. For measurement, the range of the largest and smallest foam particles is measured on a flat 5cm x 5cm cross-section.

[0094]

[0095]

[0096] Comparative Example 1: After adjusting the weight ratio of material A and material B, the viscosity of the foaming liquid increased, the foaming ratio decreased, but the strength of the foam increased, and the maximum creep and permanent deformation rate were greatly enhanced.

[0097] Comparative Example 2: Without the addition of modified fumed silica, the foaming liquid exhibited poor fluidity and uneven foaming.

[0098] Comparative Example 3: Starch with a linear content of 55-58% was used. Because of the higher branching content, the viscosity of the foaming liquid increased during the cross-linking and gelatinization process, the toughness of the foam decreased, and the foam became more brittle.

[0099] Comparative Example 4: Without the addition of a foaming agent, the foaming uniformity was poor, and the bubbles collapsed after merging.

Claims

1. An atmospheric pressure starch foaming glue, characterized by, The preparation raw materials of the glue include A material, B material, foaming agent, uniform foaming agent, and foam stabilizer, and the weight ratio of the A material to the B material is (2-5):(6-10). The preparation raw materials of the A material include 15-30 parts of starch, 3-8 parts of paste agent, and 50-100 parts of water. The preparation raw materials of the B material include 25-40 parts of starch, 0.1-0.3 parts of crosslinking agent, 8-10 parts of plasticizer, and 20-30 parts of water. The straight-chain content of the starch is 70-73%. The foaming agent includes ADC foaming agent, sodium bicarbonate, and superfine silicon dioxide, and the weight ratio is (3-6):(2-5):(0.5-1). The A material and the B material are mixed to obtain a mixed material, 8-10 parts of foaming agent, 1-3 parts of uniform foaming agent, and 0.05-0.2 parts of foam stabilizer are added to 100 parts of the mixed material, and the atmospheric pressure starch foaming glue is prepared after stirring. The uniform foaming agent includes at least one of polyether modified silicone oil, Tween 20, Tween 40, Tween 60, Tween 61, Tween 80, Tween 81, and Tween 85.

2. The atmospheric pressure starch foaming glue according to claim 1, characterized in that, The starch includes at least one of corn starch, cassava starch, wheat starch, potato starch, sweet potato starch, legume starch, and rice starch.

3. The atmospheric pressure starch foaming glue according to claim 1, characterized in that, The viscosity of the atmospheric pressure starch foaming glue is 10000-20000 Pa.s.

4. A process for the preparation of atmospheric pressure starch foaming glue according to any one of claims 1-3, characterized in that, The preparation method includes: S1. Preparing the A material: adding the starch into water and stirring, continuously adding the paste agent, stirring and keeping warm to obtain the A material; S2. Preparing the B material: adding the starch, crosslinking agent, and plasticizer into water and stirring to obtain the B material; S3. Adding the A material into the B material according to the weight ratio, mixing, adding the foaming agent, uniform foaming agent, and foam stabilizer, and stirring to obtain the atmospheric pressure starch foaming glue.

5. A method of using atmospheric starch foamed glue according to any one of claims 1-3 or prepared according to claim 4, characterized in that: The atmospheric pressure starch foaming glue is coated in the interlayer of two pieces of foaming film, the foaming film is sealed around, and the semi-finished product is obtained by winding, and the semi-finished product is heated under atmospheric pressure to realize foaming during use.

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