High-initial-viscosity hot melt adhesive containing LDPE-g-SMA as well as preparation method and application of high-initial-viscosity hot melt adhesive

Abstract

The invention discloses a high-initial-viscosity hot melt adhesive containing LDPE-g-SMA as well as a preparation method and application of the high-initial-viscosity hot melt adhesive. The high-initial-viscosity hot melt adhesive containing LDPE-g-SMA provided by the invention comprises the following components in percentage by weight: 10-25% of a main polymer; 40%-60% of tackifying resin; 1% to 10% of LDPE-g-SMA (Low Density Polyethylene 10%-25% of white mineral oil; and 0.1%-2% of an antioxidant. The preparation method of the high-initial-viscosity hot melt adhesive containing LDPE-g-SMA comprises the following steps: mixing all the components, vacuumizing, heating and stirring until the materials are completely molten, stopping stirring, and vacuumizing and defoaming. The high-initial-viscosity hot melt adhesive containing LDPE-g-SMA has high adhesive power, is suitable for non-polar base materials, can meet the production requirements of high-speed production lines, and is simple in preparation method, low in production cost and suitable for large-scale industrial production and application.

Description

Technical Field

[0001] This invention relates to the field of hot melt adhesive technology, specifically to a high initial tack hot melt adhesive containing LDPE-g-SMA, its preparation method, and its application. Background Technology

[0002] Hot melt adhesives are flexible adhesives widely used in hygiene products, labels, and packaging. However, existing hot melt adhesives for these applications often suffer from insufficient adhesion on non-polar substrates (e.g., pure cotton, perforated cotton nonwoven fabric, imitation cotton nonwoven fabric, fluffy / smooth hot-air nonwoven fabric, etc.), leading to bonding difficulties. Furthermore, existing hot melt adhesives for hygiene products, labels, and packaging may experience glue seepage (leading to unnecessary bonding) when used on high-speed production lines, failing to fully meet the production requirements. Currently, the common approach to addressing this issue is reducing the amount of adhesive used. While this method effectively reduces seepage, it also reduces adhesive strength, posing a risk of incomplete bonding.

[0003] CN 106520017 A discloses a single-component moisture-curing polyolefin hot melt adhesive and its preparation method. By adding a coupling agent and an initiator to the polyolefin hot melt adhesive formulation and carrying out an irreversible curing reaction under humid conditions, the adhesion strength between the hot melt adhesive and the non-polar substrate is increased. This chemically reactive hot melt adhesive is heavily dependent on moisture, and the curing speed is limited. CN111592841A discloses a UV-curable polyolefin hot melt adhesive and its preparation method. By adding a photoinitiator and an additive to the formulation and then forming a crosslinking network through UV curing, the adhesion strength of the hot melt adhesive is improved. However, the introduction of UV light irradiation process inevitably involves the modification of existing equipment.

[0004] Therefore, it is of great significance to develop a hot melt adhesive with high adhesion, suitable for non-polar substrates, and capable of meeting the production requirements of high-speed production lines. Summary of the Invention

[0005] The purpose of this invention is to provide a high initial tack hot melt adhesive containing LDPE-g-SMA, its preparation method, and its application.

[0006] The technical solution adopted in this invention is:

[0007] A high initial tack hot melt adhesive containing LDPE-g-SMA, comprising the following components by weight percentage:

[0008] Main polymer: 10%–25%;

[0009] Tackifying resin: 40%–60%;

[0010] LDPE-g-SMA: 1%–10%;

[0011] White mineral oil: 10%–25%;

[0012] Antioxidant: 0.1%–2%.

[0013] Preferably, the main polymer is at least one selected from styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene-butene-styrene block copolymer (SEBS), and ethylene-vinyl acetate copolymer (EVA).

[0014] Preferably, the tackifying resin is at least one of petroleum resin, hydrogenated C5 petroleum resin, hydrogenated DCPD petroleum resin, hydrogenated C9 resin, rosin resin, and maleic anhydride modified rosin resin.

[0015] Preferably, the LDPE-g-SMA (LDPE copolymerized with styrene and maleic anhydride) is prepared by a method including the following steps: mixing low-density polyethylene (LDPE), styrene (St), maleic anhydride (MAH) and an initiator for melt grafting to obtain LDPE-g-SMA.

[0016] Preferably, the total weight of the styrene and maleic anhydride is 3% to 12% of the weight of the low-density polyethylene.

[0017] Preferably, the weight ratio of styrene to maleic anhydride is 2.0 to 2.5:1.

[0018] Preferably, the number average molecular weight of the low-density polyethylene is 50,000 g / mol to 500,000 g / mol.

[0019] Preferably, the initiator is at least one of dicumyl peroxide (DCP), benzoyl peroxide (BPO), di-tert-butyl peroxide (DTBP), and cumyl hydroperoxide (CHP).

[0020] Preferably, the initiator is 0.3% to 0.7% of the total weight of low-density polyethylene, styrene, and maleic anhydride.

[0021] Preferably, the fusion grafting is performed at a temperature of 180°C to 200°C.

[0022] Preferably, the white mineral oil is a naphthenic oil with a weight percentage of cycloalkanes greater than 40%.

[0023] Preferably, the antioxidant is at least one of antioxidant 1010 (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]), antioxidant 1076 (octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), antioxidant 264 (2,6-di-tert-butyl-4-methylphenol), antioxidant DLTP (dilauryl thiodipropionate), antioxidant DSTP (dioctadecyl thiodipropionate), and antioxidant 168 (tris[2,4-di-tert-butylphenyl]phosphite).

[0024] A method for preparing a high initial tack hot melt adhesive containing LDPE-g-SMA as described above includes the following steps:

[0025] Mix all components, then heat and stir under vacuum until the material is completely melted. Stop stirring and degas under vacuum to obtain a high initial tack hot melt adhesive containing LDPE-g-SMA.

[0026] Preferably, the vacuum heating and stirring is carried out at a temperature of 150℃~160℃ and a vacuum degree of -0.10MPa~-0.08MPa.

[0027] A high initial tack hot melt adhesive containing LDPE-g-SMA as described above is used for bonding non-polar substrates.

[0028] The beneficial effects of the present invention are: the hot melt adhesive of the present invention has high adhesion, is suitable for non-polar substrates, can meet the production requirements of high-speed production lines, and has a simple preparation method and low production cost, making it suitable for large-scale industrial production and application.

[0029] Specifically:

[0030] 1) The hot melt adhesive of the present invention contains LDPE-g-SMA, which can significantly improve the adhesion of the hot melt adhesive (high initial tack, high holding tack), making the hot melt adhesive suitable for non-polar substrates such as pure cotton surface layer, perforated cotton non-woven fabric, imitation cotton non-woven fabric, fluffy / smooth hot air non-woven fabric;

[0031] 2) The hot melt adhesive of the present invention contains LDPE-g-SMA, which can effectively reduce the curing time of the hot melt adhesive and enhance its wettability, so that the hot melt adhesive can meet the production requirements of high-speed production lines.

[0032] 3) The hot melt adhesive of the present invention has a simple preparation method, low production cost, and does not require special production equipment, making it suitable for large-scale industrial production and application. Attached Figure Description

[0033] Figure 1 The reaction route diagram for LDPE-g-SMA-3 in Example 1 is shown.

[0034] Figure 2 The FTIR plots of LDPE and LDPE-g-St in Comparative Example 2 are shown.

[0035] Figure 3 The graph shows the rheological properties of the high initial tack hot melt adhesive containing LDPE-g-SMA in Example 1 and the hot melt adhesive in Comparative Example 1. Detailed Implementation

[0036] The present invention will be further explained and described below with reference to specific embodiments.

[0037] Example 1:

[0038] A high initial tack hot melt adhesive containing LDPE-g-SMA has the following composition:

[0039] Table 1. Composition of a high initial tack hot melt adhesive containing LDPE-g-SMA

[0040]

[0041] Note:

[0042] Preparation method of LDPE-g-SMA-3 (synthetic route as follows) Figure 1 As shown below:

[0043] LDPE (LD605 from Beijing Yanshan Petrochemical Co., Ltd., China Petrochemical Corporation), styrene (St, Qilu Branch of China Petroleum & Chemical Corporation), maleic anhydride (MAH, Shandong Zhengyu Chemical Technology Co., Ltd.), and dicumyl peroxide (DCP, Norinone) were used. The mixture (BC-FF) was homogeneous. The total weight of St and MAH was 3% of the weight of LDPE, the weight ratio of St to MAH was 7:3, and the weight of dicumyl peroxide was 0.5% of the total weight of LDPE, St and MAH. The mixture was then transferred to a twin-screw extruder for melt grafting at 190°C. The extrusion conditions were: residence time t = 2.5 min, speed r = 100 rpm, and then pelletized to obtain LDPE-g-SMA-3.

[0044] The preparation method of the above-mentioned high initial tack hot melt adhesive containing LDPE-g-SMA is as follows:

[0045] Mix all components, heat to 155℃ and evacuate to a vacuum degree of -0.08MPa, then stir until the material is completely melted. Stop stirring and evacuate to remove bubbles, thus obtaining a high initial tack hot melt adhesive containing LDPE-g-SMA.

[0046] Example 2:

[0047] A high initial tack hot melt adhesive containing LDPE-g-SMA has the following composition:

[0048] Table 2. Composition of a high initial tack hot melt adhesive containing LDPE-g-SMA

[0049] Components Weight percentage (%) SIS (same as Example 1) 18 Hydrogenated C5 petroleum resin (same as Example 1) 47 LDPE-g-SMA-6 9 White mineral oil (same as Example 1) 25 Antioxidant 1010 (same as in Example 1) 1

[0050] Note:

[0051] The preparation method of LDPE-g-SMA-6 is the same as that of LDPE-g-SMA-3. During preparation, the total weight of St and MAH is adjusted from "3%" of the weight of LDPE to "6%".

[0052] The preparation method of the above-mentioned high initial tack hot melt adhesive containing LDPE-g-SMA is as follows:

[0053] Mix all components, heat to 155℃ and evacuate to a vacuum degree of -0.08MPa, then stir until the material is completely melted. Stop stirring and evacuate to remove bubbles, thus obtaining a high initial tack hot melt adhesive containing LDPE-g-SMA.

[0054] Example 3:

[0055] A high initial tack hot melt adhesive containing LDPE-g-SMA has the following composition:

[0056] Table 3. Composition of a high initial tack hot melt adhesive containing LDPE-g-SMA

[0057]

[0058]

[0059] Note:

[0060] The preparation method of LDPE-g-SMA-9 is the same as that of LDPE-g-SMA-3. During preparation, the total weight of St and MAH is adjusted from "3%" of the weight of LDPE to "9%".

[0061] The preparation method of the above-mentioned high initial tack hot melt adhesive containing LDPE-g-SMA is as follows:

[0062] Mix all components, heat to 155℃ and evacuate to a vacuum degree of -0.08MPa, then stir until the material is completely melted. Stop stirring and evacuate to remove bubbles, thus obtaining a high initial tack hot melt adhesive containing LDPE-g-SMA.

[0063] Example 4:

[0064] A high initial tack hot melt adhesive containing LDPE-g-SMA has the following composition:

[0065] Table 4. Composition of a high initial tack hot melt adhesive containing LDPE-g-SMA

[0066] Components Weight percentage (%) SIS (same as Example 1) 18 Hydrogenated C5 petroleum resin (same as Example 1) 47 LDPE-g-SMA-12 9 White mineral oil (same as Example 1) 25 Antioxidant 1010 (same as in Example 1) 1

[0067] Note:

[0068] The preparation method of LDPE-g-SMA-12 is the same as that of LDPE-g-SMA-3. During preparation, the total weight of St and MAH is adjusted from "3%" of the weight of LDPE to "12%".

[0069] The preparation method of the above-mentioned high initial tack hot melt adhesive containing LDPE-g-SMA is as follows:

[0070] Mix all components, heat to 155℃ and evacuate to a vacuum degree of -0.08MPa, then stir until the material is completely melted. Stop stirring and evacuate to remove bubbles, thus obtaining a high initial tack hot melt adhesive containing LDPE-g-SMA.

[0071] Comparative Example 1:

[0072] A hot melt adhesive is identical to Example 1 except that “LDPE-g-SMA” is replaced by “SIS (same as Example 1)”, and the preparation process of the hot melt adhesive is also identical to that of Example 1.

[0073] Comparative Example 2:

[0074] A hot melt adhesive is identical to Example 1 except that “LDPE-g-SMA” is replaced with “LDPE-g-St” by weight, and the preparation process of the hot melt adhesive is also identical to that of Example 1.

[0075] Note:

[0076] The preparation method of LDPE-g-St is as follows:

[0077] LDPE (LD605 from Beijing Yanshan Petrochemical Co., Ltd. of Sinopec Group), styrene (St, Qilu Branch of Sinopec Corporation), and dicumyl peroxide (DCP, Norin) were used. The mixture of BC-FF was homogeneous. The weight of St was 3% of the weight of LDPE, and the weight of dicumyl peroxide was 0.5% of the total weight of LDPE and St. The mixture was then transferred to a twin-screw extruder for melt grafting at 190°C. The extrusion conditions were: residence time t = 2.5 min, speed r = 100 rpm. The mixture was then pelletized to obtain LDPE-g-St.

[0078] The Fourier transform infrared (FTIR) spectra of LDPE and LDPE-g-St in this comparative example are shown below. Figure 2 As shown.

[0079] Depend on Figure 2 It can be seen that LDPE-g-St has three new peaks compared with LDPE, including the one at 3060 cm⁻¹. -1 and 3030cm -1 The characteristic absorption peak of CH is at 1602 cm⁻¹. -1 and 1495cm -1 The peak at 699 cm⁻¹ is the characteristic absorption peak of C=C on the benzene ring. -1 and 760cm -1 The absorption peak at this location is due to the bending vibration of the CH bond in a monosubstituted benzene ring, indicating that St was successfully grafted onto the LDPE molecular chain.

[0080] Comparative Example 3:

[0081] A hot melt adhesive is identical to Example 1 except that “LDPE-g-SMA” is replaced by “LDPE-g-MAH” by weight, and the preparation process of the hot melt adhesive is also identical to that of Example 1.

[0082] Note:

[0083] The preparation method of LDPE-g-MAH is as follows:

[0084] LDPE (LD605 from Beijing Yanshan Petrochemical Co., Ltd., Sinopec Group), maleic anhydride (MAH, Shandong Zhengyu Chemical Technology Co., Ltd.), and dicumyl peroxide (DCP, Norinone) were used. The BC-FF mixture was homogeneous. The weight of MAH was 3% of the weight of LDPE, and the weight of dicumyl peroxide was 0.5% of the total weight of LDPE and MAH. The mixture was then transferred to a twin-screw extruder for melt grafting at 190°C. The extrusion conditions were: residence time t = 2.5 min, speed r = 100 rpm. The mixture was then pelletized to obtain LDPE-g-MAH.

[0085] Performance testing:

[0086] 1) The grafting rate and grafting efficiency of LDPE-g-SMA-3 in Example 1, LDPE-g-SMA-6 in Example 2, LDPE-g-SMA-9 in Example 3, and LDPE-g-SMA-12 in Example 4 are shown in the table below:

[0087] Table 5 Grafting rate and grafting efficiency

[0088]

[0089]

[0090] Note:

[0091] w SMA The percentage of the total weight of St and MAH added during the preparation of LDPE-g-SMA relative to the weight of LDPE.

[0092] The formula for calculating the grafting rate GP is as follows: (w1-w0) / w1×100%, where w0 is the weight of LDPE and w1 is the weight of LDPE-g-SMA after extraction to remove ungrafted St and MAH.

[0093] The formula for calculating the grafting efficiency GE is as follows: (w1-w0) / w2×100%, where w0 is the weight of LDPE, w1 is the weight of LDPE-g-SMA after extraction to remove ungrafted St and MAH, and w2 is the total weight of St and MAH added during the preparation of LDPE-g-SMA.

[0094] The specific operation for removing ungrafted St and MAH by LDPE-g-SMA extraction is as follows: LDPE-g-SMA is added to xylene and heated under reflux to dissolve, then acetone is added for precipitation. The precipitate is then extracted with acetone in a Soxhlet extractor for 12 hours (to remove unreacted St and MAH), and the extracted product is then placed in a vacuum drying oven for vacuum drying.

[0095] As shown in Table 5, both St and MAH can be efficiently grafted onto the LDPE molecular chain under different amounts of St and MAH, indicating that the free radical initiation grafting method can successfully and efficiently graft St and MAH onto the LDPE molecular chain.

[0096] 2) The rheological properties of the high initial tack hot melt adhesive containing LDPE-g-SMA in Example 1 and the hot melt adhesive in Comparative Example 1 were tested using a rheometer. The test results are as follows: Figure 3 As shown.

[0097] Depend on Figure 3 It can be seen that: in the temperature range of 10℃ to 40℃, the loss modulus G” of the high initial tack hot melt adhesive containing LDPE-g-SMA in Example 1 is less than that of the hot melt adhesive in Comparative Example 1, indicating that the high initial tack hot melt adhesive containing LDPE-g-SMA in Example 1 has a lower tactile viscosity; in the temperature range of 70℃ to 110℃, the loss tangent tan(δ) value of the high initial tack hot melt adhesive containing LDPE-g-SMA in Example 1 is higher than that of the hot melt adhesive in Comparative Example 1, indicating that the high initial tack hot melt adhesive containing LDPE-g-SMA in Example 1 has better wetting properties and a stronger adhesion between the hot melt adhesive and the substrate, thereby achieving high adhesion.

[0098] 3) The high initial tack hot melt adhesives containing LDPE-g-SMA from Examples 1-4 and the hot melt adhesives from Comparative Examples 1-3 were used in a high-speed diaper production line for end sealing and side sealing of diaper products. The end seal peel strength, side seal peel strength, and feel of the obtained hot melt adhesives are shown in the table below:

[0099] Table 6. Test results of end-seal peel force, side-seal peel force, and tactile feel of hot melt adhesive used in high-speed diaper production lines.

[0100]

[0101]

[0102] Note:

[0103] End seal peel strength and edge seal peel strength: Tested according to "GB / T 2791-1995 Adhesives T Peel Strength Test Method Flexible Materials to Flexible Materials".

[0104] As shown in Table 6, the high initial tack hot melt adhesives containing LDPE-g-SMA in Examples 1 to 4 can firmly adhere to the substrate when used for end sealing or side sealing of diaper products in high-speed diaper production lines. Compared with the hot melt adhesives in Comparative Documents 1 to 3, the adhesion is significantly improved and the feel is drier.

[0105] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A high initial tack hot melt adhesive containing LDPE-g-SMA, characterized in that, Includes the following components by weight percentage: Main polymer: 10%–25%; Tackifying resin: 40%–60%; LDPE-g-SMA: 1%–10%; White mineral oil: 10%–25%; Antioxidant: 0.1%–2%.

2. The high initial tack hot melt adhesive containing LDPE-g-SMA according to claim 1, characterized in that: The main polymer is at least one of styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylene-butene-styrene block copolymer, and ethylene-vinyl acetate copolymer.

3. The high initial tack hot melt adhesive containing LDPE-g-SMA according to claim 1, characterized in that: The tackifying resin is at least one of petroleum resin, hydrogenated C5 petroleum resin, hydrogenated DCPD petroleum resin, hydrogenated C9 resin, rosin resin, and maleic anhydride modified rosin resin.

4. The high initial tack hot melt adhesive containing LDPE-g-SMA according to any one of claims 1 to 3, characterized in that: The LDPE-g-SMA is prepared by a method including the following steps: mixing low-density polyethylene, styrene, maleic anhydride and an initiator and performing melt grafting to obtain LDPE-g-SMA.

5. The high initial tack hot melt adhesive containing LDPE-g-SMA according to claim 4, characterized in that: The total weight of styrene and maleic anhydride is 3% to 12% of the weight of low-density polyethylene; the weight ratio of styrene to maleic anhydride is 2.0 to 2.5:

1.

6. The high initial tack hot melt adhesive containing LDPE-g-SMA according to claim 4, characterized in that: The number average molecular weight of the low-density polyethylene is 50,000 g / mol to 500,000 g / mol.

7. The high initial tack hot melt adhesive containing LDPE-g-SMA according to claim 4, characterized in that: The fusion grafting is performed at a temperature of 180℃ to 200℃.

8. The high initial tack hot melt adhesive containing LDPE-g-SMA according to any one of claims 1 to 3, characterized in that: The white mineral oil is a naphthenic oil with a weight percentage of naphthenes greater than 40%; the antioxidant is at least one of antioxidant 1010, antioxidant 1076, antioxidant 264, antioxidant DLTP, antioxidant DSTP, and antioxidant 168.

9. A method for preparing a high initial tack hot melt adhesive containing LDPE-g-SMA as described in any one of claims 1 to 8, characterized in that, The process includes the following steps: mixing all components, then heating and stirring under vacuum until the material is completely melted, then stopping stirring and degassing under vacuum to obtain a high initial tack hot melt adhesive containing LDPE-g-SMA.

10. The application of a high initial tack hot melt adhesive containing LDPE-g-SMA as described in any one of claims 1 to 8 for bonding non-polar substrates.

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