Low-temperature water-mist-resistant hot-melt pressure-sensitive label adhesive as well as preparation method and application thereof

Abstract

The invention provides a low-temperature water-mist-resistant hot-melt pressure-sensitive label adhesive as well as a preparation method and application thereof, and relates to the technical field of hot-melt pressure-sensitive adhesives, the low-temperature water-mist-resistant hot-melt pressure-sensitive label adhesive is prepared from polyisobutene, an SSBR / SIS thermoplastic elastomer, hydrogenated petroleum resin, terpene-phenol resin, rosin resin, naphthenic oil, polyethylene wax and an antioxidant according to a specific ratio. The low-temperature water-mist-resistant hot-melt pressure-sensitive label adhesive prepared by the invention has excellent low-temperature labeling performance and excellent water mist resistance, solves the technical problems that labels in the fields of cold chains and the like are easy to embrittle, warp and fall off in a low-temperature and high-humidity environment, and keeps good initial adhesion, stripping force and cohesive force balance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hot melt pressure sensitive adhesive, in particular to a hot melt adhesive special for labels which can maintain bonding performance at low temperature and in high humidity / water mist environment and a preparation method thereof. BACKGROUND

[0002] In many industrial production and daily life scenes, the use of labels is ubiquitous, bearing important functions such as information identification, traceability, decoration, etc.

[0003] However, when the label is in a special environment of low temperature and water mist, the existing ordinary label adhesive often exposes many defects that are difficult to overcome, which seriously limits its application range. For example, in cold chain logistics, the packaging surface of frozen food, medicine, etc. often produces condensation water mist due to temperature difference, and the label needs to face the dual severe tests of low temperature and water vapor. Label peeling and blurring will lead to information loss, directly affecting product traceability and management safety; in the scene of cold storage equipment, equipment identification in outdoor low temperature environment, etc., similar problems also exist.

[0004] The root cause is that the existing ordinary hot melt pressure sensitive adhesive label adhesive on the market is mainly designed for normal temperature dry environment. At low temperature, the glue body is prone to embrittlement, resulting in significant reduction of adhesion, and significant reduction of initial adhesion and holding adhesion; when there is water mist on the surface of the adherend, water molecules will invade the adhesive interface, destroy the adhesion between the adhesive layer and the surface of the adherend, and it is more difficult to maintain good adhesion, resulting in label edge lifting and peeling.

[0005] The existing technology cannot stably meet the harsh needs of these low temperature and high humidity special environments, and the market urgently needs a new adhesive solution that can effectively solve this technical problem.

[0006] Therefore, the present application is designed to overcome the deficiencies of the prior art, and provides a hot melt pressure sensitive adhesive with excellent comprehensive performance, especially high adhesion strength and stability in low temperature and water mist environment, and a preparation method thereof. SUMMARY

[0007] The present application aims to overcome the deficiencies of the prior art and provide a hot melt pressure sensitive adhesive with excellent comprehensive performance, especially high adhesion strength and stability in low temperature and water mist environment, and a preparation method thereof.

[0008] In order to solve the above problems, the present application adopts the following technical scheme: A low temperature and water mist resistant hot melt pressure sensitive label adhesive, comprising the following components by weight: Naphthenic oil 5-12 parts; Polyisobutylene 10-22 parts; SSBR thermoplastic elastomer 30-45 parts; SIS thermoplastic elastomer 3-10 parts; Hydrogenated petroleum resin 10-20 parts; Terpene phenol resin 10-20 parts; Rosin resin 5-15 parts; Polyethylene wax 1-5 parts; Antioxidant 1-2 parts.

[0009] Preferably, the SIS thermoplastic elastomer is a high styrene content SIS thermoplastic elastomer, such as YH-1209.

[0010] The preparation method of the hot melt pressure sensitive adhesive comprises the following steps: Add naphthenic oil, polyisobutylene, hydrogenated petroleum resin, part of terpene phenol resin and antioxidant into the stirred tank, stir and heat to 110±5℃; Add 50wt% of the total amount of SSBR thermoplastic rubber into the stirred tank, stir for 10 minutes, then add the remaining SSBR thermoplastic rubber, and stir for another 10 minutes; Add SIS thermoplastic elastomer, continue to stir and heat; Add polyethylene wax, continue to stir and heat until the wax and rubber are completely melted; Add the remaining terpene phenol resin and rosin resin, stir for 30 minutes until all materials are evenly mixed, discharge, cool, cut into particles and package.

[0011] The hot melt pressure sensitive adhesive is used in the preparation of labels used in low temperature or high humidity environments.

[0012] Compared with the prior art, the present application has the following remarkable advantages: 1. Through the synergistic softening effect of polyisobutylene, naphthenic oil and SSBR / SIS thermoplastic elastomer system, the glass transition temperature (Tg) of the adhesive is greatly reduced, and the minimum labeling temperature can reach-20℃, and the adhesive can maintain good adhesion within the use temperature range of-50℃~70℃.

[0013] 2. The extreme hydrophobicity of polyisobutylene and the dense filling and shielding effect of polyethylene wax produce a synergistic effect, forming an effective waterproof barrier in the adhesive layer, greatly reducing the adsorption and penetration of water, so that the label can be firmly pasted on objects with condensation water on the surface without the phenomenon of label lifting and falling off.

[0014] 3. The scientific compounding of SSBR (providing low temperature flexibility and die cutting property) and high cohesive SIS (providing cohesive force) makes the adhesive have moderate holding adhesion while maintaining high initial adhesion and peeling force, effectively preventing glue overflow and giving the product excellent die cutting and waste removal performance.

[0015] 4. The adhesive is suitable for various substrates (such as copper plate paper, thermal paper, PET, PP synthetic paper, etc.) and various surfaces (such as paper boxes, PE bags, glass, metal, plastic, etc.), and is particularly suitable for harsh use environments such as cold chain logistics, outdoor signs, beverage ice bottles, etc. BRIEF DESCRIPTION OF DRAWINGS

[0016] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the application. In the drawings:

[0017] Wherein: Figure 1 is an experimental data chart highlighting the initial ring tack performance in the present application; Figure 2 is an experimental data chart highlighting the 180° peel performance in the present application; Figure 3 is an experimental data chart highlighting the 90° peel performance in the present application; Figure 4 is an experimental data chart highlighting the holding tack time performance in the present application; Figure 5 is an experimental data chart highlighting the shear failure temperature performance in the present application; Figure 6 is an experimental data chart highlighting the minimum label temperature performance in the present application. DETAILED DESCRIPTION

[0018] In order to make the technical problems to be solved by the present application, the technical solutions and beneficial effects more clear, explicit, the following will be combined with the drawings and examples, the present application is further described in detail. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0019] (1) Experimental raw materials Naphthenic oil: Xinjiang Karamay Refinery, KN-4010 Polyisobutylene (PIB): Korea Daling Industry Co., Ltd., PB2400 SSBR thermoplastic elastomer: Italy ENI Company, 1205 SIS thermoplastic elastomer: Sinopec Hunan Petrochemical Co., Ltd., YH-1209 Hydrogenated petroleum resin: Exxon Mobil Corporation, Escorez5300 Terpene phenol resin: Kortec Company, 1105 Rosin resin: Guangdong Kemao Lin Chemical Co., Ltd., KA-100L Polyethylene wax: Malaysia Shell Company, PX105 Antioxidant: BASF, 1010 Equipment: 500L jacketed heating stirred tank, anchor stirrer, coater, universal material testing machine, etc.

[0020] (2) Preparation method: According to the weight ratio shown in Table 1, each component was weighed and prepared according to the following steps: Step one: add naphthenic oil, polyisobutylene, hydrogenated petroleum resin, part of terpene phenol resin and antioxidant to the stirred tank, start stirring, and heat to 110±5℃.

[0021] Step two: add 50% of the proportion of SSBR thermoplastic rubber to the stirred tank, stir for 10 minutes, then add the remaining 50% of the proportion of SSBR thermoplastic rubber, stir for 10 minutes, then add SIS thermoplastic elastomer, continue to stir and heat.

[0022] Step three: continue to stir and heat for 30 minutes, then add polyethylene wax, continue to stir and heat until the wax and rubber are completely melted.

[0023] Step four: finally add the remaining terpene phenol resin and rosin resin, stir for 30 minutes until all materials are completely mixed and uniform, discharge, cool, dry, package to obtain hot melt pressure sensitive adhesive.

[0024] (3) Preparation of performance test sample: The obtained hot melt pressure sensitive adhesive was heated to a molten state at 170℃, and test labels with a glue layer thickness of about 20μm (coating amount about 20gsm) were prepared on synthetic paper (face material) and white grid lasin paper (base paper) by a label coater, and cut into corresponding sizes required for testing.

[0025] (4) Test method: 1. Initial adhesion test of ring shape Test standard: refer to GB / T31125-2014 method A (tensile tester method).

[0026] Sample preparation: cut the label sample into a strip with a width of 25mm and a length of 175mm. Use 25mm wide release paper to cover the two ends of the sample with the adhesive surface exposed.

[0027] Test process: bend the sample into a tear-drop-shaped ring (circumference 125mm), so that the middle part of the ring completely contacts the center of the standard test plate (25mm×25mm area) placed horizontally by its own weight. Then vertically pull up the tensile testing machine at a speed of 300mm / min, and record the required maximum force value in units of Newton / inch (N / inch).

[0028] 2. 180° peel strength and 90° peel strength test Test Standard: Refer to GB / T2792-2014.

[0029] Sample Preparation: Cut the label sample into a strip with width of 25mm and length of 200mm.

[0030] Test Procedure: Place the sample adhesive side down on a clean stainless steel plate with the sample lengthwise parallel to the edge of the plate. Place the plate with the sample under a 2kg motorized roller and roll back and forth 2 times at a speed of 10mm / s. Then fold the unattached end 180° (or 90°) and clamp it into the upper clamp of a tensile testing machine and pull at a rate of 300mm / min. Record the average force in Newton / inch (N / inch) during steady state peeling. Also observe and record the type of failure.

[0031] 3. Pick Resistance Test Test Standard: Refer to GB / T4851-2014.

[0032] Sample Preparation: Cut the label sample into a strip with width of 25mm and length of 100mm.

[0033] Test Procedure: Attach the sample to a clean stainless steel plate with an area of 25mm x 25mm. Roll the sample 2 times with a 2kg roller as described above. Fix the plate vertically on a pick resistance tester and hang a weight from the unattached end of the sample (total weight including the loading plate, hook and weight is 1000±10g). Record the time in hours (h) for the sample to completely slide off the plate.

[0034] 4. Shear Failure Temperature Test Test Standard: Refer to GB / T36794—2018 “Determination of Shear Failure Temperature of Adhesive Tape”.

[0035] Sample Preparation: Same as Pick Resistance Test.

[0036] Test Procedure: Attach the sample to a plate and hang a weight (total weight is 500±10g) as described in the Pick Resistance Test. Then place the entire apparatus in a SAFT test chamber and program the temperature to increase at a rate of 0.5℃ / min. Record the temperature in degrees Celsius (℃) at which the sample completely slides off the plate, which is the shear failure temperature (SAFT).

[0037] 5. Minimum Labeling Temperature: Place the sample in different low temperatures (e.g. 5, 0, -5, -10, -15, -20, -25℃) and attach it to a carton, express bag, etc. with a manual roller to apply appropriate pressure to ensure adhesion. The criteria for passing are (1) no label lifting and (2) the peeling force is not less than a certain threshold. Record the minimum temperature that meets the criteria in degrees Celsius.

[0038] 6. Water mist resistance: Sample preparation: The label sample was cut into a strip with a width of 50 mm and a length of 100 mm.

[0039] The label was attached to the surface of a PE bag, a PP bottle, etc. with water mist (formed by a container filled with water frozen at -20°C for 24 h and then taken out and placed at room temperature for 1 h) hanging on the surface. After 24 hours, the evaluation was as follows: (1) whether the label was warped (warped label was judged as unqualified); (2) the label was manually torn to evaluate the peel strength (small peel strength was judged as unqualified).

[0040] (5) Examples and comparative examples: According to the above preparation method and test method, the samples of the following formulations were prepared and performance tested, and the results are recorded in Table 2.

[0041] Table 1: Formulation table of each example and comparative example (parts by weight)

[0042] Table 2: Performance test results

[0043] (6) Conclusion and analysis In combination with the above experimental results: Figures 1-6 In terms of low temperature performance, the polyisobutylene molecular structure is a saturated straight chain olefin without double bonds, and the molecular chain flexibility is high, which is not easy to crystallize or harden at low temperature, and can significantly reduce the glass transition temperature (Tg) of the hot melt pressure sensitive adhesive. The molecular structure of naphthenic oil contains more cyclic structures, which is not easy to crystallize at low temperature, and the viscosity changes little with temperature, which can be used as a softener to reduce Tg. The experimental data confirms the above analysis. The comparative example does not use polyisobutylene, and the minimum labeling temperature is only -12°C. All examples add 10-22 parts of polyisobutylene, combined with naphthenic oil, so that the minimum labeling temperature is significantly reduced to -15°C or even -20°C, ensuring that the hot melt pressure sensitive adhesive still maintains good flexibility and interfacial wettability in low temperature environment, effectively avoiding the decline in adhesion due to low temperature embrittlement.

[0044] ​In terms of water mist resistance, polyisobutylene has strong hydrophobicity, and no polar groups in the molecular chain, which is not easy to combine with water molecules. Polyethylene wax has a regular molecular structure and high crystallinity, and has strong hydrophobicity. The non-polar segment in the molecule can reduce the adsorption of water molecules on the surface of the adhesive layer, and at the same time can fill the micro voids in the interior of the adhesive layer, optimize the compactness of the film structure, and reduce the migration channel of water molecules through the adhesive layer. The performance test results fully reflect the synergistic effect of the two. The comparative example does not use the two key components, and the water mist resistance is "poor", the label is off and the label loses adhesion. After adding polyisobutylene and polyethylene wax, the water mist resistance of examples 2-5 all reaches "good" or "excellent", and there is no label off phenomenon. In particular, example 1 (without adding polyethylene wax) only shows "slight label off", which directly contrasts with examples 2 and 3, proving the key role of polyethylene wax in enhancing the compactness of the adhesive layer and blocking water vapor penetration.

[0045] In terms of balance of cohesion and adhesion, SSBR thermoplastic rubber has a small molecular weight, can maintain good elasticity and flexibility at low temperature, and can increase the die cutting performance of the label, but excessive use will cause the overall cohesion of the hot melt pressure sensitive adhesive to be weak, which is easy to cause overflow. It needs to be matched with high styrene content high cohesion YH-1209SIS thermoplastic rubber to balance the cohesion and adhesion of the adhesive. Polyisobutylene has a high molecular weight and high cohesion, which can maintain the structural stability of the adhesive layer in a low temperature and high humidity environment. The comparative example uses a large amount of SIS (35 parts) and a small amount of SSBR (5 parts), although the holding time is as long as 98.9h, but the cohesion is too strong and the compatibility is poor, which is not conducive to the synergistic effect of each component. The present application (such as example 3 using SSBR:SIS=35:3) maintains an excellent level of holding time of 67.3h by scientific compounding, while obtaining good initial adhesion and peeling force, which proves that the combination effectively balances the cohesion and adhesion, avoids the overflow phenomenon, and ensures the long-term bonding effect.

[0046] In summary, the present application produces a significant synergistic effect through the innovative combination of polyisobutylene, SSBR / SIS compounded rubber system and polyethylene wax. Experimental data prove that on the premise of not excessively sacrificing the holding force (67.3h) and heat resistance (75℃), the present application successfully solves the two core technical problems of traditional hot melt pressure sensitive adhesive (comparative example) in low temperature environment (brittleness at-12℃ compared with-20℃) and failure in the presence of water mist (serious label off compared with no label off). The technical effect is unexpected for those skilled in the art, has outstanding substantial characteristics and significant progress.

[0047] The application is described above in conjunction with the drawings, and it is obvious that the specific implementation of the application is not limited by the above manner, as long as various non-essential improvements are made by using the method concept and technical solution of the application, or the concept and technical solution of the application is directly applied to other occasions without improvement, which are all within the protection scope of the application.

Claims

1. A low temperature water resistant, mist resistant, hot melt pressure sensitive label adhesive characterized in that, By weight, the following components are included: Naphthenic oil 5-12 parts; Polyisobutylene 10-22 parts; SSBR thermoplastic elastomer 30-45 parts; SIS thermoplastic elastomer 3-10 parts; Hydrogenated petroleum resin 10-20 parts; Terpene phenol resin 10-20 parts; Rosin resin 5-15 parts; Polyethylene wax 1-5 parts; Antioxidant 1-2 parts.

2. The low temperature water resistant hot melt pressure sensitive label adhesive of claim 1 wherein, The SIS thermoplastic elastomer is a high styrene content SIS thermoplastic elastomer.

3. The low temperature water resistant hot melt pressure sensitive label adhesive of claim 1 wherein, The polyisobutylene is added in an amount of 15-20 parts.

4. The low temperature water resistant hot melt pressure sensitive label adhesive of claim 1 wherein, The SSBR thermoplastic rubber is added in an amount of 30-35 parts.

5. The low temperature water resistant hot melt pressure sensitive label adhesive of claim 1 wherein, The polyethylene wax is added in an amount of 2-3 parts.

6. A process for the preparation of a low temperature water-mist resistant hot melt pressure sensitive adhesive according to any one of claims 1 to 5, characterized in that, The following steps are included: S1: Mix naphthenic oil, polyisobutylene, part of tackifying resin and antioxidant, and heat to 110±5℃; S2: Add SSBR thermoplastic rubber in batches, and stir; S3: Add SIS thermoplastic elastomer, stir and continue to heat; S4: Add polyethylene wax, stir and heat to complete melting; S5: Add the remaining tackifying resin, stir until mixed evenly, and then discharge.

7. The process for preparing a low temperature water resistant hot melt pressure sensitive label adhesive according to claim 6, characterized in that, In step S2, the SSBR thermoplastic rubber is added in two times, and each time is stirred for 10 minutes after addition.

8. The process for preparing a low temperature water resistant hot melt pressure sensitive label adhesive according to claim 6, characterized in that, The tackifying resin includes hydrogenated petroleum resin, terpene phenol resin and rosin resin.

9. A label characterized in that, The adhesive layer is made of the hot melt pressure sensitive adhesive of any one of claims 1-5.

10. Use of the hot melt pressure sensitive adhesive of any one of claims 1-5 or the label of claim 9 in the identification of articles in low temperature or high humidity environments.

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