High-temperature-resistant hot melt adhesive for food bag bonding and preparation method thereof

Abstract

The application relates to hot melt adhesive for bonding high-temperature-resistant food bags and a preparation method thereof, and relates to the technical field of hot melt adhesive. The hot melt adhesive comprises the following components in percentage by weight: naphthenic oil 10-20%, SIS rubber 20-30%, SBS rubber 3-8%, petroleum resin 30-40%, rosin resin 10-30%, crystalline wax 3-8%, phenolic antioxidant 0.1-1%, and phosphite antioxidant 0.1-1%. The hot melt adhesive uses SIS rubber and SBS rubber as the base material, and the content of styrene is increased to ensure the high-temperature resistance. The crystalline wax is added to modify the hot melt adhesive and improve the high-temperature resistance, so that the bonding of the hot melt adhesive can resist the high temperature of food. The petroleum resin and rosin resin are added as tackifiers to improve the adhesion and stability of the adhesive layer. Through reasonable collocation of the components, the hot melt adhesive can maintain excellent adhesion performance at high temperature, has low-temperature breaking performance, and is safe and non-toxic.

Description

Technical Field

[0001] This invention belongs to the field of hot melt adhesive technology, specifically relating to a high-temperature resistant hot melt adhesive for bonding food bags and its preparation method. Background Technology

[0002] Food bags are paper-plastic composite bags used for food packaging. The main raw materials for their plastic film are generally polyethylene and polypropylene. These food bags are odorless, non-toxic, corrosion-resistant, and safe for human use, but they are not easy to seal. Ordinary adhesives contain small amounts of toxic and volatile solvents, which can harm human health.

[0003] Hot melt adhesives, as environmentally friendly adhesives, are non-toxic, odorless, solvent-free, highly malleable, and have a simple and pollution-free production process, making them highly promising for the field of hot melt adhesives for food bag bonding. However, general hot melt adhesives are only suitable for use at room temperature. When used to hold food at high temperatures (above 65°C) for extended periods, problems such as decreased adhesion and delamination can easily occur. Furthermore, at low temperatures, the moisture on the food surface freezes and adheres to the food bag; if the adhesive viscosity is too high, it hinders the removal of the food. Therefore, it is necessary to research a hot melt adhesive that exhibits excellent adhesion at high temperatures while also maintaining good low-temperature material breaking performance. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, one of the objectives of this invention is to provide a hot melt adhesive for bonding high-temperature food bags, which maintains excellent adhesion at high temperatures, has low-temperature material breaking properties, and is safe and non-toxic.

[0005] The second objective of this invention is to provide a method for preparing a hot melt adhesive for bonding high-temperature food bags. The preparation process is simple, non-toxic, and pollution-free.

[0006] One of the objectives of this invention is achieved through the following technical solution:

[0007] A high-temperature resistant hot melt adhesive for bonding food bags comprises the following components by weight percentage:

[0008]

[0009] Furthermore, it includes the following components by weight percentage:

[0010]

[0011] Furthermore, the naphthenic oil has a viscosity of 50-500 cps at 40°C.

[0012] Furthermore, the styrene content in the SIS rubber is 15-40%.

[0013] Furthermore, the styrene content in the SBS rubber is 20-40%.

[0014] Further, the petroleum resin is any one of DCPD resin, C5 petroleum resin, C9 petroleum resin, C5 / C9 copolymer resin or its hydrogenation, and the softening point of the petroleum tackifying resin is 90-120℃.

[0015] The softening point of the rosin resin is 90-120℃.

[0016] Furthermore, the crystalline wax is any one or more of PE wax, PP wax, and Fischer wax; the melting point of the crystalline wax is 90-120℃.

[0017] Further, the phenolic antioxidant is any one or more of 2,6-di-tert-butyl-p-cresol, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate;

[0018] The phosphite antioxidant is tris[2,4-di-tert-butylphenyl]phosphite.

[0019] The second objective of this invention is achieved by the following technical solution:

[0020] A method for preparing a high-temperature resistant hot melt adhesive for bonding food bags includes the following steps:

[0021] 1) Heat and stir the petroleum resin and rosin resin in the prescribed amounts until uniform to obtain the thickening resin;

[0022] 2) After heating the reactor, add naphthenic oil, SIS rubber, SBS rubber, crystallizing wax, phenolic antioxidants, phosphite antioxidants and part of the tackifying resin into the reactor, stir at low speed and simultaneously vacuum until the material is completely melted, then add the remaining tackifying resin, vacuum again until the material is free of bubbles, and then discharge.

[0023] Furthermore, in step 1), the heating temperature is 130-140℃, and the stirring speed is 50-120 rpm;

[0024] In step 2), the heating temperature is 150-165℃, the initial addition amount of the tackifying resin is 30-60% of its total mass, the vacuum degree of the vacuum treatment is -0.09 to -0.07 MPa, the low-speed stirring rate is 10-60 rpm, the stirring time is 1-2 h, the vacuum degree of the second vacuum treatment is -0.09 to -0.07 MPa, and the second vacuum holding time is 40-60 min.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] This invention discloses a high-temperature resistant hot melt adhesive for bonding food bags, comprising naphthenic oil, SIS rubber (styrene-isoprene-styrene copolymer), SBS rubber (styrene-butadiene-styrene copolymer), petroleum resin, rosin resin, crystallizing wax, phenolic antioxidants, and phosphite antioxidants. The use of SIS rubber and SBS rubber, with an increased styrene content, ensures high-temperature resistance. The addition of crystallizing wax modifies the hot melt adhesive, further enhancing its high-temperature resistance and making the adhesive more resistant to the high temperatures of food.

[0027] Naphthenic oils possess high solubility and excellent low-temperature performance, exhibiting excellent compatibility with SIS and SBS rubbers and improving dispersibility. By controlling the naphthenic oil content, hot melt adhesives can achieve a balance between low-temperature material breaking performance and other desirable properties. The addition of petroleum resin and rosin resin as tackifiers enhances the adhesion and stability of the adhesive layer, preventing oil seepage. Phenolic antioxidants and phosphite antioxidants delay the oxidation of polymeric compounds, thereby extending the product's service life. The formulation of this invention, through the rational combination of its components, enables the hot melt adhesive to maintain excellent adhesion at high temperatures, possess low-temperature material breaking performance, and is safe and non-toxic.

[0028] This invention discloses a method for preparing a high-temperature resistant hot melt adhesive for food bags. The method involves heating and mixing the raw materials in the formulation without adding any solvents or toxic / harmful substances during the preparation process. The resulting hot melt adhesive is an environmentally friendly and non-toxic adhesive. Furthermore, a two-stage vacuum process is employed, where stirring under vacuum allows for uniform mixing of materials at a lower stirring rate, improving the degree of blending and removing air bubbles. This ensures the product maintains sufficient cohesion, exhibits high stability, and is less prone to oil leakage. The preparation method of this invention is simple, pollution-free, and suitable for mass production. Detailed Implementation

[0029] The present invention will now be further described in conjunction with specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0030] Example 1

[0031] A high-temperature resistant hot melt adhesive for bonding food bags comprises the following components by weight percentage:

[0032]

[0033]

[0034] The naphthenic oil has a viscosity of 120-160 cps at 40°C.

[0035] The SIS rubber contains 30% styrene.

[0036] The SBS rubber contains 40% styrene.

[0037] The petroleum resin is C5 petroleum resin, and the softening point of the petroleum tackifying resin is 100°C.

[0038] The softening point of the rosin resin is 100°C.

[0039] The crystalline wax is Fischer wax; the melting point of the crystalline wax is 100°C.

[0040] The phenolic antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate];

[0041] The phosphite antioxidant is tris[2,4-di-tert-butylphenyl]phosphite.

[0042] The preparation method of the hot melt adhesive for bonding high-temperature food bags includes the following steps:

[0043] 1) Heat and stir the petroleum resin and rosin resin in the prescribed amounts until uniform to obtain the thickening resin; the heating temperature is 135℃ and the stirring speed is 60rpm.

[0044] 2) After heating the reactor to 160℃, add naphthenic oil, SIS rubber, SBS rubber, crystallizing wax, phenolic antioxidants, phosphite antioxidants, and 50% of the total mass of tackifying resin into the reactor. Stir at a low speed of 30 rpm while simultaneously applying a vacuum of -0.08 MPa for 1.5 hours until the material is completely melted. Then add the remaining tackifying resin and apply a second vacuum of -0.08 MPa for 50 minutes until the material is free of bubbles. Finally, discharge the material.

[0045] Example 2

[0046] A high-temperature resistant hot melt adhesive for bonding food bags comprises the following components by weight percentage:

[0047]

[0048] The naphthenic oil has a viscosity of 120-160 cps at 40°C.

[0049] The SIS rubber contains 38% styrene.

[0050] The SBS rubber contains 38% styrene.

[0051] The petroleum resin is DCPD resin, and the softening point of the petroleum tackifying resin is 100°C.

[0052] The softening point of the rosin resin is 100°C.

[0053] The crystalline wax is Fischer wax; the melting point of the crystalline wax is 100°C.

[0054] The phenolic antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate];

[0055] The phosphite antioxidant is tris[2,4-di-tert-butylphenyl]phosphite.

[0056] The preparation method of the hot melt adhesive for bonding high-temperature food bags includes the following steps:

[0057] 1) Heat and stir the petroleum resin and rosin resin in the prescribed amounts until uniform to obtain the thickening resin; the heating temperature is 140℃ and the stirring speed is 60rpm.

[0058] 2) After heating the reactor to 165℃, add naphthenic oil, SIS rubber, SBS rubber, crystallizing wax, phenolic antioxidants, phosphite antioxidants, and 50% of the total mass of tackifying resin into the reactor. Stir at a low speed of 30 rpm while simultaneously applying a vacuum of -0.08 MPa for 1.5 hours until the material is completely melted. Then add the remaining tackifying resin and apply a second vacuum of -0.08 MPa for 50 minutes until the material is free of bubbles. Finally, discharge the material.

[0059] Example 3

[0060] A high-temperature resistant hot melt adhesive for bonding food bags comprises the following components by weight percentage:

[0061]

[0062] The naphthenic oil has a viscosity of 120-160 cps at 40°C.

[0063] The SIS rubber contains 32% styrene.

[0064] The SBS rubber contains 40% styrene.

[0065] The petroleum resin is a C5 / C9 copolymer resin, and the softening point of the petroleum tackifying resin is 100°C.

[0066] The softening point of the rosin resin is 100°C.

[0067] The crystalline wax is Fischer wax; the melting point of the crystalline wax is 100°C.

[0068] The phenolic antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate];

[0069] The phosphite antioxidant is tris[2,4-di-tert-butylphenyl]phosphite.

[0070] The preparation method of the hot melt adhesive for bonding high-temperature food bags includes the following steps:

[0071] 1) Heat and stir the petroleum resin and rosin resin in the prescribed amounts until uniform to obtain the thickening resin; the heating temperature is 130℃ and the stirring speed is 60rpm.

[0072] 2) After heating the reactor to 155℃, add naphthenic oil, SIS rubber, SBS rubber, crystallizing wax, phenolic antioxidants, phosphite antioxidants, and 50% of the total mass of tackifying resin into the reactor. Stir at a low speed of 30 rpm while simultaneously applying a vacuum of -0.08 MPa for 2 hours until the material is completely melted. Then add the remaining tackifying resin and apply a second vacuum of -0.08 MPa for 50 minutes until the material is free of bubbles. Finally, discharge the material.

[0073] Example 4

[0074] A high-temperature resistant hot melt adhesive for bonding food bags comprises the following components by weight percentage:

[0075]

[0076] The naphthenic oil has a viscosity of 120-160 cps at 40°C.

[0077] The SIS rubber contains 30% styrene.

[0078] The SBS rubber contains 40% styrene.

[0079] The petroleum resin is C5 petroleum resin, and the softening point of the petroleum tackifying resin is 100°C.

[0080] The softening point of the rosin resin is 100°C.

[0081] The crystalline wax is Fischer wax; the melting point of the crystalline wax is 100°C.

[0082] The phenolic antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate];

[0083] The phosphite antioxidant is tris[2,4-di-tert-butylphenyl]phosphite.

[0084] The preparation method of the hot melt adhesive for bonding high-temperature food bags includes the following steps:

[0085] 1) Heat and stir the petroleum resin and rosin resin in the prescribed amounts until uniform to obtain the thickening resin; the heating temperature is 135℃ and the stirring speed is 60rpm.

[0086] 2) After heating the reactor to 160℃, add naphthenic oil, SIS rubber, SBS rubber, crystallizing wax, phenolic antioxidants, phosphite antioxidants, and 50% of the total mass of tackifying resin into the reactor. Stir at a low speed of 30 rpm while simultaneously applying a vacuum of -0.08 MPa for 1.5 hours until the material is completely melted. Then add the remaining tackifying resin and apply a second vacuum of -0.08 MPa for 50 minutes until the material is free of bubbles. Finally, discharge the material.

[0087] Comparative Example 1

[0088] This comparative example provides a high-temperature resistant hot melt adhesive for bonding food bags, which differs from Example 1 only in that it includes the following components by weight percentage:

[0089]

[0090] Comparative Example 2

[0091] This comparative example provides a hot melt adhesive for bonding high-temperature food bags, which differs from Example 1 only in that the styrene content in the SIS rubber is 15%.

[0092] Comparative Example 3

[0093] This comparative example provides a high-temperature resistant hot melt adhesive for bonding food bags, which differs from Example 1 only in that it includes the following components by weight percentage:

[0094]

[0095] Performance testing

[0096] The hot melt adhesives for bonding high-temperature food bags from Examples 1-4 and Comparative Examples 1-3 were subjected to high-temperature bonding strength tests and material breaking temperature tests, respectively; wherein, the temperature for the high-temperature bonding strength test was 70°C and the high-temperature duration was 2 hours; the test results are shown in Table 1.

[0097] Table 1

[0098] Example 1 No glue coming undone 0 Example 2 No glue coming undone 1 Example 3 No glue coming undone -1 Example 4 No glue coming undone 4 Comparative Example 1 glue coming undone -5 Comparative Example 2 Partial delamination -3 Comparative Example 3 Partial delamination -2

[0099] As shown in Table 1, the hot melt adhesives for bonding high-temperature food bags in Examples 1-4 of the present invention exhibit strong high-temperature bonding with no delamination. The minimum breaking temperature is -1 to 4°C. They maintain excellent adhesion at high temperatures while also possessing low-temperature delamination properties, and are safe and non-toxic. In Comparative Example 1, without the addition of crystallizing wax, the bonding performance at high temperatures significantly decreased, with complete delamination occurring after 2 hours at 70°C, and the minimum breaking temperature was also relatively low. In Comparative Example 2, the styrene content in the SIS rubber was too low, resulting in a decrease in adhesive strength at high temperatures and localized delamination, with a lower minimum breaking temperature. In Comparative Example 3, without the addition of SBS rubber, the adhesive strength at high temperatures decreased, localized delamination occurred, and the minimum breaking temperature also decreased.

[0100] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A hot melt adhesive for bonding high-temperature resistant food bags, characterized in that, Includes the following components by weight percentage: Naphthenic oil 13-17% SIS rubber 20-24% SBS rubber 4-6% Petroleum resin 31-35% 18-22% rosin resin Crystallized wax 4-7% Phenolic antioxidants 0.1-0.5% Phosphite antioxidants: 0.1-0.5%; The naphthenic oil has a viscosity of 50-500 cps at 40°C; The styrene content in the SIS rubber is 15-40%; The styrene content in the SBS rubber is 20-40%; The petroleum resin is any one of DCPD resin, C5 petroleum resin, C9 petroleum resin, C5 / C9 copolymer resin or its hydrogenation, and the softening point of the petroleum resin is 90-120℃. The softening point of the rosin resin is 90-120℃; The crystalline wax is any one or more of PE wax, PP wax and Fischer-Tropsch wax, and the melting point of the crystalline wax is 90-120℃. The phenolic antioxidant is any one or more of 2,6-di-tert-butyl-p-cresol, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate. The phosphite antioxidant is tris[2,4-di-tert-butylphenyl]phosphite.

2. A method for preparing the hot melt adhesive for bonding high-temperature food bags as described in claim 1, characterized in that, Includes the following steps: 1) Heat and stir the petroleum resin and rosin resin in the prescribed amounts until uniform to obtain the tackifying resin; 2) After heating the reactor, add naphthenic oil, SIS rubber, SBS rubber, crystallizing wax, phenolic antioxidants, phosphite antioxidants and part of the tackifying resin into the reactor, stir at low speed and simultaneously vacuum until the materials are completely melted, then add the remaining tackifying resin, vacuum again until there are no more bubbles in the materials, and then discharge the material.

3. The preparation method of the hot melt adhesive for bonding high-temperature food bags as described in claim 2, characterized in that: In step 1), the heating temperature is 130-140℃, and the stirring speed is 50-120 rpm; In step 2), the heating temperature is 150-165℃, the initial addition amount of the tackifying resin is 30-60% of its total mass, the vacuum degree of the vacuum treatment is -0.09 to -0.07 MPa, the low-speed stirring rate is 10-60 rpm, the stirring time is 1-2 h, the vacuum degree of the second vacuum treatment is -0.09 to -0.07 MPa, and the second vacuum holding time is 40-60 min.

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