A high-temperature-resistant polyurethane hot melt adhesive film formula and a preparation method thereof

Abstract

The application discloses a kind of high-temperature-resistant polyurethane hot melt adhesive film formula and preparation method thereof, belong to polyurethane hot melt adhesive technical field.The application provides a kind of high-temperature-resistant TPU type hot melt adhesive film formula: polyol 60-75 parts, diisocyanate 25-32 parts, chain extender 10-14 parts, catalyst 2-4 parts, cage type poly silesquioxane 12-18 parts, diatomite 9-15 parts, crosslinking additive 0.5-2 parts, antioxidant 0.3-3 parts, the polyol is composed of polycarbonate diol, modified polyoxypropylene diol and propylene oxide-ethylene oxide copolymer ether triol.The polyurethane hot melt adhesive film prepared by the application overcomes the limitations of traditional TPU type hot melt adhesive in high-temperature scene, has excellent high-temperature resistance and final adhesive strength, and has lower application threshold compared with PUR type hot melt adhesive, and has good market competitiveness.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of polyurethane hot melt adhesive, and particularly relates to a formula of a high-temperature-resistant polyurethane hot melt adhesive film and a preparation method thereof. BACKGROUND

[0002] Polyurethane hot melt adhesive forms initial adhesion after being applied by melting and cooling, and realizes final curing through physical or chemical cross-linking. With the advantages of fast curing speed, high bonding strength and good elasticity and toughness, the polyurethane hot melt adhesive is widely used in the fields of automobile manufacturing, electronic packaging, textile compounding and furniture assembly. Current commercial products are mainly divided into two categories: thermoplastic polyurethane (TPU) type and moisture reaction type polyurethane (PUR) type. The two types are essentially different in molecular structure design, resulting in significant differentiation in performance characteristics and application scenarios.

[0003] The PUR type hot melt adhesive introduces an isocyanate group, and triggers cross-linking reaction through absorbing environmental moisture to form a three-dimensional network structure. Although this chemical curing mechanism endows it with excellent temperature resistance (long-term use temperature can reach above 140℃), solvent resistance and high bonding strength, at the same time, the moisture chemical cross-linking curing is an irreversible process, and the adhesive cannot be repaired after being applied, in addition, the complex curing process also requires special equipment and airtight application system, which significantly increases the overall cost and application threshold.

[0004] Unlike the PUR type hot melt adhesive, the TPU type hot melt adhesive has the characteristics of repeated melting and curing based on a linear molecular chain structure. Its core advantages are: strong process compatibility, which can be processed by using conventional extrusion equipment, and reversible curing process, which can be recycled and reused. Compared with the PUR type hot melt adhesive, the raw material and process cost of the TPU type hot melt adhesive is significantly reduced, and the initial adhesion strength is higher and the curing time is shorter. However, due to the thermoplastic nature, its heat resistance is generally lower than 120℃, and it is prone to creep or adhesion decay in high temperature environment, which has obvious limitations in engine compartment wire harness fixing and electronic component high temperature packaging scenarios.

[0005] Therefore, it is still necessary to study a high-temperature-resistant TPU type hot melt adhesive to solve the problem that the process performance of the current PUR type hot melt adhesive product is not perfect, resulting in a high application threshold. SUMMARY

[0006] In view of the content in the background art, the purpose of the present application is to provide a formula of a high-temperature-resistant polyurethane hot melt adhesive film and a preparation method thereof. By further optimizing the raw material formula, the present application overcomes the defects of poor high-temperature resistance and low final adhesion strength of traditional TPU type hot melt adhesive, thereby effectively expanding the application range of TPU type hot melt adhesive.

[0007] To achieve the above purpose, the present application specifically adopts the following technical solutions:

[0008] The application provides a high-temperature-resistant polyurethane hot melt adhesive film formula which comprises the following raw materials in parts by weight:

[0009] polyhydric alcohol 60-75 parts,

[0010] diisocyanate 25-32 parts,

[0011] chain extender 10-14 parts,

[0012] catalyst 2-4 parts,

[0013] cage polysilsesquioxane 12-18 parts,

[0014] diatomite 9-15 parts,

[0015] crosslinking additive 0.5-2 parts,

[0016] antioxidant 0.3-3 parts.

[0017] The polyhydric alcohol is composed of polycarbonate diol, modified polypropylene oxide diol and propylene oxide-ethylene oxide copolymer ether triol.

[0018] Further, the polyhydric alcohol is composed of polycarbonate diol, modified polypropylene oxide diol and propylene oxide-ethylene oxide copolymer ether triol in a mass ratio of 10: (3.2-4.5) : (3-6).

[0019] Further, the preparation method of the modified polypropylene oxide diol is as follows: the polypropylene oxide diol is preheated and dehydrated in a protective gas, then a polymerization inhibitor, a catalyst and a solvent are sequentially added, and glycidyl methacrylate is slowly added under constant temperature heating and stirring, and the modified polypropylene oxide diol is obtained after the reaction is completed.

[0020] Further, the polymerization inhibitor is 4-methoxyphenol, and the catalyst is tetrabutylammonium bromide; the mass ratio of polypropylene oxide diol, 4-methoxyphenol, tetrabutylammonium bromide and glycidyl methacrylate is 100: (0.1-0.2) : (0.05-0.3) : (6-11).

[0021] Further, the diisocyanate is at least one of 4,4'-diphenylmethane diisocyanate, isophorone diisocyanate and hexamethylene diisocyanate.

[0022] Further, the chain extender is hydroquinone dihydroxyethyl ether.

[0023] Further, the catalyst is dibutyltin dilaurate.

[0024] Further, the cage polysilsesquioxane is vinyl heptyloctyl cage polysilsesquioxane.

[0025] Further, the cross-linking additive is trimethylolpropane.

[0026] The application further provides a preparation method of the high-temperature-resistant polyurethane hot melt adhesive film.

[0027] Step one: ingredients are weighed according to the formula, and polyol, diisocyanate, catalyst and cage polysilsesquioxane are mixed, stirred and reacted at 90-100 DEG C in a protective atmosphere for 1-2 hours, and then vacuum degassing is performed to obtain a prepolymer;

[0028] Step two: the prepolymer obtained in step one is mixed with a chain extender, diatomite, a cross-linking additive and an antioxidant, and stirred and reacted at 85-90 DEG C in a protective atmosphere for 1.5-3 hours, and then cast curing is performed after the reaction is completed, and the high-temperature-resistant polyurethane hot melt adhesive film is obtained after cooling.

[0029] The traditional TPU type hot melt adhesive is formed by micro-phase separation of a soft segment (polyester polyol / polyether polyol) and a hard segment (formed by reaction of diisocyanate and a chain extender) to form a physical cross-linking network, and the glass transition temperature of the soft segment is low, the movement ability of the soft segment chain segment is enhanced at high temperature, and the molecular chain slip is intensified, resulting in material creep failure, the hydrogen bond between the hard segments is the main force of the physical cross-linking network, but the bond energy is low, and the storage modulus sharply decreases when the temperature rises. Based on this, in view of the limitations of the soft segment / hard segment performance of the traditional TPU type hot melt adhesive, glycidyl methacrylate is used to graft modify polyoxypropylene diol, and then polyol is formed by mixing polycarbonate diol and propylene oxide-ethylene oxide copolyether triol in a certain proportion; at the same time, the soft segment / hard segment ratio is further adjusted, the molecular chain is designed to build a more suitable matrix molecular framework for cage polysilsesquioxane, and the subsequent embedding of the ethenyl heptaoctyl cage polysilsesquioxane as a molecular reef is promoted, so that the thermal motion of the molecular chain at high temperature can be more deeply limited, the stability of the overall molecular framework and the thermal stability of the physical cross-linking network are greatly improved, and the high-temperature resistance of the obtained TPU type hot melt adhesive is significantly improved. In addition, diatomite has a natural porous structure, can form an internal mechanical tooth structure, and further improves the mechanical properties and temperature resistance; a small amount of trimethylolpropane is additionally added as a cross-linking additive, can control weak cross-linking and inhibit high-temperature flow, and also can improve the high-temperature resistance of the TPU type hot melt adhesive.

[0030] Compared with the prior art, the application has the following beneficial effects:

[0031] The application constructs a more suitable matrix molecular framework of the ethenyl heptaoctyl cage-shaped poly silesquioxane by precisely designing the molecular chain through a preferred raw material formula, effectively promotes the deeper embedding of the subsequent ethenyl heptaoctyl cage-shaped polysilsesquioxane as a molecular reef, and builds a moderate crosslinking network, so that the material can have more excellent thermal stability under high temperature conditions, and the prepared TPU type hot melt adhesive can have reliable bonding performance under a wider high temperature condition. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the present application will be clearly and completely described below in combination with examples. If the specific conditions are not indicated in the examples, the conventional conditions or the conditions suggested by the manufacturer are used. If the manufacturers of the reagents or instruments are not indicated, the conventional products that can be purchased in the market are used.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0034] Example 1

[0035] A preparation method of a high-temperature-resistant polyurethane hot melt adhesive film, comprising the following steps:

[0036] 1. The reaction kettle is vacuumed and replaced with nitrogen, and after repeating three times, 100 parts by weight of polyoxypropylene glycol (molecular weight 2000) is added, preheated at 80℃ for 50 min, and then 0.15 parts of 4-methoxyphenol, 0.2 parts of tetrabutylammonium bromide and 18 parts of toluene are added in sequence and stirred uniformly, heated to 92℃ and kept constant, continuously stirred and slowly added 8 parts of glycidyl methacrylate (control 75 min to add completely), continue to stir until the FTIR detection of epoxy group consumption reaches more than 95%, stop heating, remove the solvent and unreacted substances, and obtain the glycidyl methacrylate grafted modified polyoxypropylene glycol.

[0037] 2. The polyol is prepared by mixing polycarbonate diol (molecular weight 1800), modified polyoxypropylene glycol prepared in step 1 and CHE-330N copolyether triol in a mass ratio of 10:3.8:4.5. The polyol, diisocyanate (4,4'-diphenylmethane diisocyanate), chain extender (hydroquinone dihydroxyethyl ether), catalyst (dibutyltin dilaurate), ethenyl heptaoctyl cage-shaped polysilsesquioxane, diatomite, trimethylolpropane and antioxidant 1010 are weighed in parts by weight as 68, 28, 12, 3, 16, 12, 1.2 and 1.5, respectively.

[0038] 3. Mix the polyol, diisocyanate, catalyst, and vinyl heptaoctyl cage polysilsesquioxane, and stir the mixture at 95°C for 1.5 hours under a nitrogen atmosphere. Vacuum degassing is performed to obtain a prepolymer. Then mix the prepolymer with the chain extender, diatomite, trimethylolpropane, and antioxidant, and stir the mixture at 88°C for 2.5 hours under a nitrogen atmosphere. After the reaction is completed, cast curing is performed, and the product is cooled to obtain a high-temperature-resistant polyurethane hot melt adhesive film (width: 90 mm, thickness: 0.2 mm, length: 100 yards per roll).

[0039] Example 2

[0040] A method for preparing a high-temperature-resistant polyurethane hot melt adhesive film, comprising the steps of:

[0041] 1. A reaction kettle is vacuumed and replaced with nitrogen. After repeating the process three times, 100 parts by weight of polyoxypropylene glycol (molecular weight: 2000) is preheated at 80°C for 50 minutes. Then 0.1 parts of 4-methoxyphenol, 0.05 parts of tetrabutylammonium bromide, and 18 parts of toluene are added and stirred uniformly. The temperature is raised to 92°C and kept constant. Stirring is continued and 6 parts of glycidyl methacrylate is slowly added (controlled to be added completely in 60 minutes). Stirring is continued until the FTIR detection of epoxy group consumption is more than 95%. Heating is stopped, and the solvent and unreacted substances are removed to obtain glycidyl methacrylate grafted modified polyoxypropylene glycol.

[0042] 2. Polycarbonate diol (molecular weight: 1800), modified polyoxypropylene glycol prepared in step 1, and epoxypropane-ethylene oxide copolymer CHE-330N are mixed in a mass ratio of 10:3.2:6 to obtain a polyol. The polyol, diisocyanate (4,4'-diphenylmethane diisocyanate), chain extender (hydroquinone dihydroxyethyl ether), catalyst (dibutyltin dilaurate), vinyl heptaoctyl cage polysilsesquioxane, diatomite, trimethylolpropane, and antioxidant 1010 are weighed in parts by weight to obtain 60 parts of polyol, 25 parts of diisocyanate, 10 parts of chain extender, 2 parts of catalyst, 12 parts of vinyl heptaoctyl cage polysilsesquioxane, 9 parts of diatomite, 0.5 parts of trimethylolpropane, and 0.3 parts of antioxidant 1010.

[0043] 3. Mix the polyol, diisocyanate, catalyst, and vinyl heptaoctyl cage polysilsesquioxane, and stir the mixture at 95°C for 1.5 hours under a nitrogen atmosphere. Vacuum degassing is performed to obtain a prepolymer. Then mix the prepolymer with the chain extender, diatomite, trimethylolpropane, and antioxidant, and stir the mixture at 88°C for 2.5 hours under a nitrogen atmosphere. After the reaction is completed, cast curing is performed, and the product is cooled to obtain a high-temperature-resistant polyurethane hot melt adhesive film (width: 90 mm, thickness: 0.2 mm, length: 100 yards per roll).

[0044] Example 3

[0045] A method for preparing a high-temperature-resistant polyurethane hot melt adhesive film, comprising the steps of:

[0046] 1. The reactor was evacuated and replaced with nitrogen three times, then 100 parts by weight of polyoxypropylene diol (molecular weight 2000) was added, preheated at 80°C for 50 min, then 0.2 parts of 4-methoxyphenol, 0.3 parts of tetrabutylammonium bromide and 18 parts of toluene were added in turn and stirred uniformly, the temperature was raised to 92°C and kept constant, continuous stirring and slowly adding 11 parts of glycidyl methacrylate (control 90 min to add), continue to stir until the FTIR detection of epoxy group consumption reached more than 95% to stop heating, remove the solvent and unreacted, get glycidyl methacrylate grafted modified polyoxypropylene diol.

[0047] 2. The polyol was composed of polycarbonate diol (molecular weight 1800), modified polyoxypropylene diol prepared in step 1 and epoxy propane-ethylene oxide copolymer CHE-330N in a mass ratio of 10:4.5:3. The polyol was weighed as 75 parts, diisocyanate (4,4'-diphenylmethane diisocyanate) 32 parts, chain extender (hydroquinone dihydroxyethyl ether) 14 parts, catalyst (dibutyltin dilaurate) 4 parts, vinyl seven octyl cage polysilsesquioxane 18 parts, diatomite 15 parts, trimethylolpropane 2 parts, antioxidant 1010 3 parts.

[0048] 3. The polyol, diisocyanate, catalyst, vinyl seven octyl cage polysilsesquioxane were mixed and stirred at 100°C for 1 h under nitrogen atmosphere to obtain a prepolymer; then the obtained prepolymer was mixed with chain extender, diatomite, trimethylolpropane and antioxidant, and stirred at 90°C for 1.5 h under nitrogen atmosphere. After the reaction was completed, the film was cast and cured to obtain a high-temperature-resistant polyurethane hot melt adhesive film (width 90 mm, thickness 0.2 mm, length 100 yards / roll).

[0049] Comparative Example 1

[0050] Referring to the step parameters of Example 1 of the application, the difference is only the adjustment of the polyol system, and the polyoxypropylene diol is not modified.

[0051] Comparative Example 2

[0052] Referring to the step parameters of Example 1 of the application, the difference is only the adjustment of the polyol system, and the polyoxypropylene diol is not modified.

[0053] Comparative Example 3

[0054] Referring to the step parameters of Example 1 of the present application, the only difference is that the polyol system is adjusted, the mass ratio of polycarbonate diol, modified polyoxypropylene diol and propylene oxide-ethylene oxide copolyether triol is 1:1:1.

[0055] Comparative Example 4

[0056] Referring to the step parameters of Example 1 of the present application, the only difference is that the ratio of soft segment and hard segment is adjusted, that is, the amount of polyol is adjusted to 80 parts, and the amount of diisocyanate / chain extender is adjusted to 20 parts / 8.5 parts.

[0057] Comparative Example 5

[0058] Referring to the step parameters of Example 1 of the present application, the only difference is that the methyl methacrylate cage silsesquioxane is used instead of the vinyl heptaoctyl cage polysilsesquioxane.

[0059] Comparative Example 6

[0060] Referring to the step parameters of Example 1 of the present application, the only difference is that the crosslinking additive is not included in the formula.

[0061] Test Example

[0062] The TPU type hot melt adhesive film samples obtained in Examples 1-3 and Comparative Examples 1-6 above were subjected to performance detection, and the results are shown in Table 1 (the melting point detection is based on GB / T 15332-1994, the elongation at break detection is performed by a universal testing machine, and the bonding strength detection is based on GB / T 7124-2008).

[0063] Table 1: Performance detection results of TPU hot melt adhesive film

[0064]

[0065] From the above detection results, it can be seen that the softening point of the TPU type hot melt adhesive prepared by the present application is 125-135℃, which is significantly higher than that of the traditional TPU type hot melt adhesive, and the tensile properties are excellent. Through formula optimization, the present application not only maintains the high initial adhesion strength of the TPU type hot melt adhesive itself, but also significantly improves the final adhesion strength and high temperature resistance, which is close to the weather resistance of the PUR type hot melt adhesive, and the reliable bonding strength is taken into account, and the application threshold is low, which effectively expands the application range of the TPU type hot melt adhesive.

[0066] The above-described embodiments only express several preferred embodiments of the present application, and the description is more specific and detailed, but is not used to limit the present application. It should be noted that for those skilled in the art, the present application can also have various changes and modifications, and any modification, equivalent replacement, improvement, etc. made within the concept and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A high-temperature resistant polyurethane hot melt adhesive film, characterized in that, The ingredients, by weight, include the following: 60-75 parts of polyol 25-32 parts of diisocyanate 10-14 parts of chain extender 2-4 parts of catalyst 12-18 parts of cage-type polysilsesquioxane 9-15 parts diatomaceous earth Crosslinking additive 0.5-2 parts Antioxidant 0.3-3 parts; The polyol is composed of polycarbonate diol, modified polypropylene glycol, and propylene oxide-ethylene oxide copolyether triol.

2. The high-temperature resistant polyurethane hot melt adhesive film according to claim 1, characterized in that, The polyol is composed of polycarbonate diol, modified polypropylene glycol, and propylene oxide-ethylene oxide copolyether triol in a mass ratio of 10:(3.2-4.5):(3-6).

3. The high-temperature resistant polyurethane hot melt adhesive film according to claim 2, characterized in that, The modified polypropylene glycol is prepared by preheating polypropylene glycol in a protective atmosphere to remove water, then adding polymerization inhibitor, catalyst and solvent in sequence, and slowly adding glycidyl methacrylate under constant temperature and stirring. After the reaction is completed, the modified polypropylene glycol is obtained.

4. The high-temperature resistant polyurethane hot melt adhesive film according to claim 3, characterized in that, The polymerization inhibitor is 4-methoxyphenol, and the catalyst is tetrabutylammonium bromide; the mass ratio of polypropylene glycol, 4-methoxyphenol, tetrabutylammonium bromide, and glycidyl methacrylate is 100:(0.1-0.2):(0.05-0.3):(6-11).

5. The high-temperature resistant polyurethane hot melt adhesive film according to claim 1, characterized in that, The diisocyanate is at least one of 4,4'-diphenylmethane diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate.

6. The high-temperature resistant polyurethane hot melt adhesive film according to claim 1, characterized in that, The chain extender is hydroquinone dihydroxyethyl ether.

7. The high-temperature resistant polyurethane hot melt adhesive film according to claim 1, characterized in that, The catalyst is dibutyltin dilaurate.

8. The high-temperature resistant polyurethane hot melt adhesive film according to claim 1, characterized in that, The cage-like polysilsesquioxane is vinylheptaoctyl cage-like polysilsesquioxane.

9. The high-temperature resistant polyurethane hot melt adhesive film according to claim 1, characterized in that, The crosslinking additive is trimethylolpropane.

10. A method for preparing the high-temperature resistant polyurethane hot melt adhesive film according to any one of claims 1-9, characterized in that, Includes the following steps: Step 1: Weigh all raw materials and set aside. Mix the polyol, diisocyanate, catalyst and cage-type polysilsesquioxane, and stir and react in a protective atmosphere at 90-100℃ for 1-2 hours. Degas under vacuum to obtain the prepolymer. Step 2: Mix the prepolymer obtained in Step 1 with chain extender, diatomaceous earth, crosslinking additive and antioxidant, and stir and react in a protective atmosphere at 85-90℃ for 1.5-3 h. After the reaction is completed, cast and cure, and cool to obtain high temperature resistant polyurethane hot melt adhesive film.

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