A rubber type removable pressure sensitive adhesive and a method for preparing the same

Abstract

The application belongs to the technical field of adhesives, and particularly relates to a rubber type removable pressure sensitive adhesive and a preparation method thereof. The application provides a rubber type removable pressure sensitive adhesive, and preparation raw materials include, by weight, 100 parts of styrene-isoprene-styrene block copolymer, 100-150 parts of tackifying resin, 30-70 parts of softening agent, 0.2-1.5 parts of main antioxidant and 0.2-1.5 parts of auxiliary antioxidant. The unique formula design of the application enables the adhesive to have excellent instantaneous adhesion and sufficient cohesion. The pressure sensitive adhesive of the application benefits from balanced viscoelasticity, and the adhesive can be separated in a clean interface during peeling, without any residue on the surface of the adherend (such as glass, ceramic tile and wooden paint surface) and without damaging the base material. By using hydrogenated resin and a composite antioxidant system, oxidative degradation is fundamentally inhibited, the product is not prone to yellowing, brittle and oiling during long-term use, and has a long service life.

Description

Technical Field

[0001] This application belongs to the field of adhesive technology, specifically relating to a rubber-type removable pressure-sensitive adhesive and its preparation method. Background Technology

[0002] Pressure-sensitive adhesives (PSA) are adhesive materials that can adhere to various surfaces with slight pressure. Currently, products on the market for portable applications are mainly divided into acrylic and rubber types.

[0003] Acrylic pressure-sensitive adhesives have the advantages of being resistant to aging and yellowing, but their initial tack is usually low and their adhesion to non-polar surfaces (such as some plastics) is insufficient, making it difficult to meet the "instant adhesion" requirement of products such as refrigerator magnets.

[0004] Traditional rubber-based pressure-sensitive adhesives (such as those based on natural rubber) have high initial tack, but they also have significant drawbacks: Poor aging resistance: The unsaturated double bonds in natural rubber are easily oxidized, causing the rubber layer to yellow, harden, lose its stickiness, and even ooze oily substances to contaminate the attached surface.

[0005] Insufficient cohesive strength: It is prone to slippage or displacement at slightly higher temperatures, and cohesive failure is likely to occur during removal, resulting in colloid breakage, stringing, and residue.

[0006] Therefore, there is an urgent need in this field for a rubber-based pressure-sensitive adhesive formulation that can take into account high initial tack, excellent cohesive strength, long-lasting portability (no residue), and excellent aging resistance and low-temperature performance. Summary of the Invention

[0007] To achieve the above objectives, the present invention adopts the following technical solution: The core of this invention is to provide a rubber-type removable pressure-sensitive adhesive, which, by weight, comprises the following raw materials: 100 parts of styrene-isoprene-styrene block copolymer, 100-150 parts of tackifying resin, 30-70 parts of softener, 0.2-1.5 parts of primary antioxidant, and 0.2-1.5 parts of secondary antioxidant.

[0008] Preferably, the raw materials for preparation include: 100 parts of styrene-isoprene-styrene block copolymer, 120-140 parts of tackifying resin, 40-60 parts of softener, 0.4-0.6 parts of primary antioxidant, and 0.4-0.6 parts of secondary antioxidant.

[0009] More preferably, the raw materials include: 100 parts of styrene-isoprene-styrene block copolymer, 130 parts of tackifying resin, 50 parts of softener, 0.5 parts of primary antioxidant, and 0.5 parts of secondary antioxidant.

[0010] The styrene-isoprene-styrene block copolymer (SIS) serves as the backbone of the system, with its polystyrene end groups forming a physical cross-linked network that provides cohesive strength and elasticity; the polyisoprene middle segments provide viscosity and flexibility. This structure is the basis for achieving "portability".

[0011] Preferably, the styrene-isoprene-styrene block copolymer (SIS) has a styrene content of 12-20%, and more preferably, the styrene content of the styrene-isoprene-styrene block copolymer (SIS) is 15-17%. The styrene content is determined using commonly used methods in the art, such as FTIR or spectrophotometry.

[0012] The diblock content of the styrene-isoprene-styrene block copolymer (SIS) is 40-60%, preferably 40-55%. The diblock content is determined using a method commonly used in the art, such as gel permeation chromatography (GPC).

[0013] Furthermore, the styrene-isoprene-styrene block copolymer (SIS) described in this application has a styrene content of 16% and a diblock content of 50%, is grade YH-1126, and is branded by Sinopec. The SIS, with its high diblock polymer content, not only exhibits excellent holding and peel strength at room temperature but also shows improved peel strength at low temperatures.

[0014] The tackifying resin includes at least one of C5 petroleum resin, C9 petroleum resin, C5 and C9 copolymer resin, hydrogenated C5 petroleum resin, hydrogenated C9 petroleum resin, hydrogenated terpene resin, and glycerol rosin ester; preferably, the tackifying resin includes hydrogenated C5 petroleum resin and glycerol rosin ester, and the weight ratio of the hydrogenated C5 petroleum resin to glycerol rosin ester is 5:7-9.

[0015] Furthermore, the rosin glycerol ester is pretreated before being added. The pretreatment steps include heating 100 parts by weight of glycerol rosin ester and 20 parts by weight of hexadecanoic acid to 250°C and holding for 5 hours.

[0016] The tackifying resin described in this application is compatible with the polyisoprene segment in SIS, effectively lowering the glass transition temperature (Tg) and imparting the necessary initial tack and peel strength. The use of hydrogenated C5 petroleum resin significantly improves the oxidation resistance and UV resistance of the pressure-sensitive adhesive, thereby avoiding the yellowing and deterioration problems of traditional rubber adhesives.

[0017] Meanwhile, adding a certain amount of pretreated glycerol rosin ester and hydrogenated C5 petroleum resin can further improve the initial viscosity and peel strength at low temperatures.

[0018] The softener comprises naphthenic oil and white mineral oil, with a weight ratio of 3-5:1. The naphthenic oil is selected from 4010, and the white mineral oil is selected from No. 10 mineral oil. The softener, in combination with the styrene-isoprene-styrene block copolymer and tackifying resin selected in this application, enables the pressure-sensitive adhesive to maintain suitable peel force and initial tack, meeting the performance requirements of removable pressure-sensitive adhesives. It is particularly suitable for preparing refrigerator magnets, decorative stickers, removable promotional materials, and other products requiring repeated adhesion without residue, and can be used in conjunction with blue release film.

[0019] The primary antioxidant is a hindered phenolic antioxidant, such as antioxidant 1076 (β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) or antioxidant 1010 (pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]).

[0020] The co-antioxidant is a phosphite antioxidant, such as tris(2,4-di-tert-butylphenyl) phosphite (antioxidant 168, trade name such as ADK STAB 2112), CAS number 31570-04-4.

[0021] The primary antioxidant (hindered phenols) and secondary antioxidant (phosphites) constitute a synergistic defense system that can effectively capture free radicals and decompose hydrogen peroxides, providing comprehensive protection for the pressure-sensitive adhesive during high-temperature melting and long-term use. This is key to ensuring the long-term stability of the product's performance.

[0022] The pressure-sensitive adhesive raw material described in this application further includes 1-5 parts by weight of silica, wherein the silica particle size is 10-30 micrometers. By adding silica, the peel performance of the adhesive can be improved, and the number of times it can be reused can be increased.

[0023] The second aspect of this application provides a method for preparing the pressure-sensitive adhesive, comprising the following steps: S1. Prepare the raw materials according to the above weight proportions.

[0024] S2 First, add styrene-isoprene-styrene block copolymer, softener, main antioxidant and auxiliary antioxidant to the inert gas protected reactor, heat to 120-160℃, and stir for 10-30 minutes; S3. Raise the temperature to 150-170℃, add hydrogenated C5 petroleum resin, glycerol rosin ester, and silicon dioxide in sequence, and continue stirring for about 1-1.5 hours. S4 removes air bubbles from the molten adhesive under a negative pressure of -0.05 to -0.08 MPa for 15-20 minutes; S5. Transfer the degassed adhesive to a storage tank, and apply it evenly to the substrate at a coating rate of 90-110 g / m² at 150-170℃. Then cool, roll up, and slit.

[0025] By adopting the above technical solution, the present invention has the following beneficial effects: The unique formulation design of this application gives the colloid excellent instantaneous adhesion ability, while having sufficient cohesion to prevent slippage, and also has excellent low-temperature performance, enabling it to be reused even at low temperatures.

[0026] This pressure-sensitive adhesive benefits from balanced viscoelastic properties, allowing for clean interfacial separation upon peeling. It leaves no residue on the adhered surface (such as glass, ceramic tiles, and wood finishes) and does not damage the substrate. By employing a hydrogenated resin and composite antioxidant system, oxidative degradation is fundamentally inhibited, ensuring the product is resistant to yellowing, brittleness, and oiling over long-term use, resulting in a long service life.

[0027] The pressure-sensitive adhesive of this application is solvent-free, environmentally friendly, and its preparation process is simple, suitable for high-speed coating production, with high efficiency and controllable cost. Detailed Implementation

[0028] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] The present invention will be further explained below with reference to specific embodiments.

[0030] Example 1 A rubber-type removable pressure-sensitive adhesive, by weight, comprises the following raw materials: 100 parts of styrene-isoprene-styrene block copolymer, 130 parts of tackifying resin, 50 parts of softener, 0.5 parts of primary antioxidant, and 0.5 parts of secondary antioxidant.

[0031] The styrene-isoprene-styrene block copolymer (SIS) has a styrene content of 16% and a diblock content of 50%, is grade YH-1126, and is branded by Sinopec.

[0032] The tackifying resin comprises hydrogenated C5 petroleum resin and glycerol rosin ester, wherein the weight ratio of hydrogenated C5 petroleum resin to glycerol rosin ester is 5:8. The rosin glycerol ester is pretreated before being added, and the pretreatment steps include: heating 100 parts by weight of glycerol rosin ester and 20 parts by weight of hexadecanoic acid to 250°C and holding at that temperature for 5 hours.

[0033] The softener comprises naphthenic oil and white mineral oil, wherein the weight ratio of naphthenic oil to white mineral oil is 4:1. The naphthenic oil is selected from 4010, and the white mineral oil is selected from No. 10 mineral oil.

[0034] The primary antioxidant is hindered phenolic antioxidant 1010, the secondary antioxidant is phosphite antioxidant 168, and the pressure-sensitive adhesive raw material also includes 3 parts by weight of silica, the silica having an average particle size of 20 micrometers.

[0035] The preparation method of the pressure-sensitive adhesive includes the following steps: S1. Prepare the raw materials according to the above weight proportions.

[0036] S2 First, add styrene-isoprene-styrene block copolymer, softener, main antioxidant and auxiliary antioxidant to the inert gas protected reactor, heat to 150°C and stir for 20 minutes; S3 raise the temperature to 160℃, add hydrogenated C5 petroleum resin, glycerol rosin ester and silicon dioxide in sequence, and continue stirring for 1 hour; S4 removes air bubbles from the molten adhesive at -0.05 to -0.08 MPa for 15 minutes; S5. Transfer the degassed adhesive to a storage tank, apply it evenly to the substrate at 160°C with a coating amount of 100 g / m², cool, roll up, and slit.

[0037] Example 2 A rubber-type removable pressure-sensitive adhesive, by weight, comprises the following raw materials: 100 parts of styrene-isoprene-styrene block copolymer, 120 parts of tackifying resin, 40 parts of softener, 0.5 parts of primary antioxidant, and 0.5 parts of secondary antioxidant.

[0038] The styrene-isoprene-styrene block copolymer (SIS) has a styrene content of 16% and a diblock content of 50%, is grade YH-1126, and is branded by Sinopec.

[0039] The tackifying resin comprises hydrogenated C5 petroleum resin and glycerol rosin ester, wherein the weight ratio of hydrogenated C5 petroleum resin to glycerol rosin ester is 5:8. The rosin glycerol ester is pretreated before being added, and the pretreatment steps include: heating 100 parts by weight of glycerol rosin ester and 20 parts by weight of hexadecanoic acid to 250°C and holding at that temperature for 5 hours.

[0040] The softener comprises naphthenic oil and white mineral oil, wherein the weight ratio of naphthenic oil to white mineral oil is 4:1. The naphthenic oil is selected from 4010, and the white mineral oil is selected from No. 10 mineral oil.

[0041] The primary antioxidant is hindered phenolic antioxidant 1010, the secondary antioxidant is phosphite antioxidant 168, and the pressure-sensitive adhesive raw material also includes 3 parts by weight of silica, the silica having an average particle size of 20 micrometers.

[0042] The specific steps for preparing the pressure-sensitive adhesive are the same as in Example 1.

[0043] Comparative Example 1 A specific embodiment of a rubber-type removable pressure-sensitive adhesive is the same as in Example 1, except that the tackifying resin comprises hydrogenated C5 petroleum resin and glycerol rosin ester, and the weight ratio of the hydrogenated C5 petroleum resin to glycerol rosin ester is 5:11. The rosin glycerol ester is pretreated before addition. The pretreatment steps include: heating 100 parts by weight of glycerol rosin ester and 20 parts by weight of hexadecanoic acid to 250°C and holding at that temperature for 5 hours.

[0044] Comparative Example 2 A specific embodiment of a rubber-type removable pressure-sensitive adhesive is the same as in Example 1, except that the tackifying resin comprises hydrogenated C5 petroleum resin and glycerol rosin ester, and the weight ratio of the hydrogenated C5 petroleum resin to glycerol rosin ester is 5:5. The glycerol rosin ester is pretreated before addition. The pretreatment steps include: heating 100 parts by weight of glycerol rosin ester and 20 parts by weight of hexadecanoic acid to 250°C and holding at that temperature for 5 hours.

[0045] Comparative Example 3 A specific embodiment of a rubber-type removable pressure-sensitive adhesive is the same as in Example 1, except that the tackifying resin comprises hydrogenated C5 petroleum resin and glycerol rosin ester, and the weight ratio of the hydrogenated C5 petroleum resin to glycerol rosin ester is 5:8. The glycerol rosin ester is pretreated before addition. The pretreatment steps include: heating 100 parts by weight of glycerol rosin ester and 20 parts by weight of undecanoic acid to 250°C and holding at that temperature for 5 hours.

[0046] Comparative Example 4 A specific embodiment of a rubber-type removable pressure-sensitive adhesive is the same as in Example 1, except that the softener includes naphthenic oil and white mineral oil, and the weight ratio of naphthenic oil to white mineral oil is 8:1. The naphthenic oil is selected from 4010, and the white mineral oil is selected from No. 10 mineral oil.

[0047] Comparative Example 5 The styrene-isoprene-styrene block copolymer (SIS) has a styrene content of 17% and a diblock content of 33%, and is selected from Kraton D1117 in the United States.

[0048] Performance testing Initial tack: determined according to GB / T 4852-2002B.

[0049] Tackiness: determined according to GB / T 4851-84.

[0050] 180° peel strength: determined according to GB / T 2792-1998. The film was coated onto a 30-micron thick high-transparency PET film using a coating applicator and tested after being left at room temperature for 24 hours.

[0051] Low-temperature 180° peel strength: determined according to GB / T 2792-1998. The film was coated onto a 30-micron thick high-transparency PET film using a coating applicator and tested after being placed at -10°C for 24 hours.

[0052]

[0053] As can be seen from the table above, in Comparative Example 1, the glycerol rosin resin will over-swell or destroy the physical cross-linking network of SIS, resulting in a significant decrease in the cohesive strength of the colloid. Therefore, cohesive failure or slippage is likely to occur in the holding test, resulting in a shortened time.

[0054] In Comparative Example 2, the proportion of glycerol rosin resin was reduced, which resulted in insufficient wetting of the bonded surface under slight pressure, thus causing the ball number in the rolling ball test to decrease.

[0055] In Comparative Example 3, the pretreated glycerol rosin ester may be unevenly dispersed in the system or have slightly poor compatibility with SIS, forming small phase separation regions.

[0056] In Comparative Example 4, the cohesive strength of the pressure-sensitive adhesive was severely weakened, and the adhesive was prone to creep or flow under continuous shear force, resulting in a sharp decrease in holding time from >72h to 56h. Additionally, adhesive residue remained during the peeling process.

[0057] The pressure-sensitive adhesive in Comparative Example 5 lacked sufficient free segments to wet the surface and form adhesion, making the adhesive too "rigid." Consequently, under slight pressure and peeling, both initial tack and peel strength were significantly lower than in the examples. At low temperatures, the molecular chain motion further froze, making the adhesive even more rigid and almost unable to deform to adapt to the bonded surface, resulting in a precipitous drop in low-temperature peel strength.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A rubber-type removable pressure-sensitive adhesive, characterized in that, The raw materials for preparation, calculated by weight, include: 100 parts of styrene-isoprene-styrene block copolymer, 100-150 parts of tackifying resin, 30-70 parts of softener, 0.2-1.5 parts of primary antioxidant, and 0.2-1.5 parts of secondary antioxidant; the styrene content of the styrene-isoprene-styrene block copolymer is 12-20%.

2. The rubber-type removable pressure-sensitive adhesive as described in claim 1, characterized in that, The raw materials for preparation, calculated by weight, include: 100 parts of styrene-isoprene-styrene block copolymer, 120-140 parts of tackifying resin, 40-60 parts of softener, 0.4-0.6 parts of primary antioxidant, and 0.4-0.6 parts of secondary antioxidant.

3. The rubber-type removable pressure-sensitive adhesive as described in claim 2, characterized in that, The raw materials for preparation, calculated by weight, include: 100 parts of styrene-isoprene-styrene block copolymer, 130 parts of tackifying resin, 50 parts of softener, 0.5 parts of primary antioxidant, and 0.5 parts of secondary antioxidant.

4. The rubber-type removable pressure-sensitive adhesive as described in claim 1, characterized in that, The styrene content of the styrene-isoprene-styrene block copolymer is 15-17% by weight.

5. The rubber-type removable pressure-sensitive adhesive as described in claim 1, characterized in that, The tackifying resin, calculated by weight, includes at least one of C5 petroleum resin, C9 petroleum resin, C5 and C9 copolymer resin, hydrogenated C5 petroleum resin, hydrogenated C9 petroleum resin, hydrogenated terpene resin, and glycerol rosin ester.

6. The rubber-type removable pressure-sensitive adhesive as described in claim 5, characterized in that, The tackifying resin comprises hydrogenated C5 petroleum resin and glycerol rosin ester in parts by weight, wherein the weight ratio of hydrogenated C5 petroleum resin to glycerol rosin ester is 5:7-9.

7. The rubber-type removable pressure-sensitive adhesive as described in claim 1, characterized in that, The softener comprises naphthenic oil and white mineral oil in a weight ratio of 3-5:1, calculated by weight.

8. The rubber-type removable pressure-sensitive adhesive as described in claim 1, characterized in that, The primary antioxidant, calculated by weight, is a hindered phenolic antioxidant.

9. The rubber-type removable pressure-sensitive adhesive as described in claim 1, characterized in that, The auxiliary antioxidant, calculated by weight, is a phosphite antioxidant.

10. A method for preparing a rubber-type removable pressure-sensitive adhesive as described in any one of claims 1-9, characterized in that, Includes the following steps: S1. Prepare the raw materials according to the above-mentioned weight proportions; S2 First, add styrene-isoprene-styrene block copolymer, softener, main antioxidant and auxiliary antioxidant to the inert gas protected reactor, heat to 120-160℃, and stir for 10-30 minutes; S3. Raise the temperature to 150-170℃, add the thickening resin one after another, and continue stirring for 1-1.5 hours; S4 removes air bubbles from the molten adhesive at -0.05 to -0.08 MPa for 15-20 minutes; S5. Transfer the degassed adhesive to a storage tank, and apply it evenly to the substrate at a coating rate of 90-110 g / m² at 150-170℃. Then cool, roll up, and slit.

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