WO2023092287A1 - High-transparency reactive polyurethane hot melt adhesive and preparation method therefor - Google Patents

Abstract

Disclosed in the present invention are a high-transparency reactive polyurethane hot melt adhesive and a preparation method therefor. The high-transparency reactive polyurethane hot melt adhesive is prepared from the following raw materials in parts by weight: 20-45 parts of an amorphous polyester polyol, 10-50 parts of a polyether polyol, 10-40 parts of an isocyanate, 10-30 parts of an acrylic resin, 0.2-2.5 parts of an adhesion promoter, 0.5-3 parts of a latent curing agent, 0.01-0.2 parts of a catalyst, 0.5-2 parts of an ultraviolet light absorber, and 0.5-2 parts of an antioxidant, wherein the isocyanate is one or more selected from cyclohexylmethane diisocyanate, isophorone diisocyanate and hexamethylene diisocyanate; and the glass transition temperature of the acrylic resin is greater than 50ºC. The reactive polyurethane hot melt adhesive has a good transparency, a good yellowing resistance, a large initial adhesion and a high curing speed, is free from obvious bubbles in an adhesive layer during curing, and has a good adhesive performance and a high final bonding strength.

Description

Highly transparent reactive polyurethane hot melt adhesive and preparation method thereof technical field

The invention relates to the field of sealants, in particular to a highly transparent reactive polyurethane hot melt adhesive and a preparation method thereof.

Background technique

Reactive polyurethane hot melt adhesive (PUR) is generally made of isocyanate-terminated (-NCO) polyurethane prepolymer as the base material and prepared with other additives. The adhesive is solid at room temperature and can be used with Water and substances containing active hydrogen react chemically to produce chemical cross-linking and curing. PUR has been rapidly developed in many industries in recent years because of its simple operation, excellent performance, and environmental friendliness.

In recent years, with the improvement of people's living standards, the requirements for the appearance of items are getting higher and higher. Transparent materials are more and more widely used in cosmetics, electronic appliances, sports equipment and other fields, and the demand for corresponding transparent adhesives is also increasing. Its performance occupies an important position in the field of transparent material bonding. But at present, most of the commercially available transparent PURs have the following problems: ① poor transparency and easy yellowing; ② low initial adhesion and slow curing speed; Pick up defects.

Contents of the invention

In view of the above technical problems, the present invention provides a highly transparent reactive polyurethane hot melt adhesive. The reactive polyurethane hot melt adhesive has excellent transparency, good yellowing resistance, high initial adhesion, fast curing speed, no obvious bubbles in the adhesive layer during curing, excellent bonding performance, and high final bonding strength.

The specific technical scheme is as follows:

A highly transparent reactive polyurethane hot-melt adhesive, prepared from the following raw materials in parts by weight: 20-45 parts of amorphous polyester polyol, 10-50 parts of polyether polyol, 10-40 parts of isocyanate, and 10 parts of acrylic resin ～30 parts, 0.2～2.5 parts of adhesion promoter, 0.5～3 parts of latent curing agent, 0.01～0.2 parts of catalyst, 0.5～2 parts of ultraviolet light absorber, 0.5～2 parts of antioxidant;

Described isocyanate is one or more in cyclohexylmethane diisocyanate (HMDI), isophorone diisocyanate (IPDI) and hexamethylene diisocyanate (HDI);

The glass transition temperature of the acrylic resin is greater than 50°C;

The adhesion promoter is 3-isocyanate propyl triethoxysilane, 3-isocyanate propyl trimethoxysilane, 3-mercaptopropyl trimethoxysilane and 3-mercaptopropyl triethoxysilane one or more;

The latent curing agent is 3-hydroxyethyl-1,3-oxazolidine, 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine, 2-phenyl-3-hydroxyethyl -1,3-oxazolidine, (S)-N-Boc-2,2-dimethyl-4-(2-hydroxyethyl)oxazolidine, 2-isopropyl-N-hydroxyethyl- One or more of oxazolidine and 2,2-dimethyl-N-hydroxyethyl-1,3-oxazolidine.

In some of these embodiments, the highly transparent reactive polyurethane hot melt adhesive is prepared from the following raw materials in parts by weight: 38-42 parts of amorphous polyester polyol, 25-30 parts of polyether polyol, 12-30 parts of isocyanate 16 parts, 15-20 parts of acrylic resin, 1.8-2.2 parts of adhesion promoter, 1.8-2.2 parts of latent curing agent, 0.05-0.15 parts of catalyst, 0.7-1.0 parts of ultraviolet light absorber, 1.0-1.4 parts of antioxidant.

In some embodiments, the glass transition temperature of the acrylic resin is greater than 55°C. Acrylic resins with a high glass transition temperature are more conducive to improving the initial adhesion of hot melt adhesives, and can also shorten the opening time of hot melt adhesives.

In some of the embodiments, the glass transition temperature of the acrylic resin is 55°C-80°C.

2013和/或

2016。 In some of these embodiments, the acrylic resin is

2013 and/or

2016.

In some of the embodiments, the hydroxyl value of the amorphous polyester polyol is 10 mgKOH/g-112 mgKOH/g.

In some of the embodiments, the hydroxyl value of the amorphous polyester polyol is 18 mgKOH/g-60 mgKOH/g.

In some of the embodiments, the hydroxyl value of the amorphous polyester polyol is 30 mgKOH/g-50 mgKOH/g.

7100系列的无定形聚酯多元醇。 In some of these embodiments, the amorphous polyester polyol is

Amorphous polyester polyols of the 7100 series.

7130和/或

7150。 In some of these embodiments, the amorphous polyester polyol is

7130 and/or

7150.

In some of these embodiments, the polyether polyol is polyoxypropylene diol.

In some of the embodiments, the polyoxypropylene diol has a number average molecular weight of 1800-2200.

7130 39～41份，数均分子量为2000的聚氧化丙烯二醇26～28份，异佛尔酮二异氰酸酯13～15份，丙烯酸树脂

2013 17～19份，3-异氰酸酯丙基三甲氧基硅烷1.9～2份，3-羟乙基-1,3-噁唑烷1.9～2份，催化剂0.05～0.15份，紫外光吸收剂0.7～1.0份，抗氧剂1.0～1.4份。 In some of these embodiments, the highly transparent reactive polyurethane hot melt adhesive is prepared from the following raw materials in parts by weight: amorphous polyester polyol

7130 39-41 parts, 26-28 parts of polyoxypropylene diol with a number average molecular weight of 2000, 13-15 parts of isophorone diisocyanate, acrylic resin

2013 17-19 parts, 1.9-2 parts of 3-isocyanate propyl trimethoxysilane, 1.9-2 parts of 3-hydroxyethyl-1,3-oxazolidine, 0.05-0.15 parts of catalyst, 0.7-2 parts of UV absorber 1.0 parts, antioxidant 1.0 to 1.4 parts.

In some of the embodiments, the catalyst is at least one of dibutyltin dilaurate (DBTDL), triethylenediamine and dimorpholino diethyl ether (DMDEE).

In some of these embodiments, the antioxidant is tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester (antioxidant 1010) and 2,6-di At least one of tert-butyl-p-cresol (antioxidant 264).

In some of these embodiments, the ultraviolet absorber is at least one of UV-123, UV-328, UV-770, UV-928 and UV-1130.

The invention also provides a preparation method of the above-mentioned highly transparent reactive polyurethane hot melt adhesive.

The specific technical scheme is as follows:

A preparation method of heat-resistant reactive polyurethane hot melt adhesive, comprising the following steps:

(1) Put the amorphous polyester polyol, polyether polyol, and acrylic resin into a reaction vessel, heat to 100°C-130°C, vacuum dehydrate for 60-180 minutes under stirring, and the vacuum degree is -0.095MPa ~-0.05MPa;

(2) Putting in the isocyanate, stirring and reacting at 100°C to 120°C for 60 minutes to 120 minutes under the protection of nitrogen or inert gas;

(3) Putting in the latent curing agent, stirring and reacting at 100° C. to 120° C. for 10 minutes to 30 minutes under the protection of nitrogen or inert gas;

(4) Add the adhesion promoter, catalyst, antioxidant, and ultraviolet absorber in sequence, and stir and mix at 100° C. to 120° C. for 20 minutes to 40 minutes under the protection of nitrogen or inert gas;

(5) Vacuum at 100°C to 120°C until no air bubbles appear, and then discharge.

The highly transparent reactive polyurethane hot-melt adhesive of the present invention selects amorphous polyester polyol, which can not only shorten the opening time of the hot-melt adhesive, but also improve the initial adhesion, and the polyurethane hot-melt adhesive prepared by amorphous polyester polyol is cooled Finally, it is a colorless and transparent solid. Compared with the crystalline polyester polyol that is a white solid after cooling, the PUR prepared by using amorphous polyester polyol has higher transparency after curing; choose to add an appropriate amount of acrylic resin When the glue cools, it can accelerate the coagulation of the hot melt adhesive, which is beneficial to improve the initial adhesion of the hot melt adhesive; choose a coupling agent with an active group isocyanate group or a mercapto group as an adhesion promoter, and a coupling agent with a mercapto group It can chemically react with NCO, and the coupling agent with isocyanate group can participate in the moisture curing reaction in the PUR moisture curing reaction. Both of them can be introduced into the crosslinking curing system. Hydrogen bonds or chemical reactions occur on the surface of the material, which can improve the adhesion of the hot melt adhesive to the bonding substrate; choose oxazolidine with hydroxyl as the latent curing agent, and its hydroxyl group can chemically react with the NCO of the PUR system, and the evil Oxazolidinyl can preferentially react with moisture in the air when PUR is moisture-cured, reduce the generation of CO ₂ gas, and prevent PUR from producing bubbles during bonding, resulting in bonding defects. The gas reaction is rapid, which can greatly increase the curing speed of the PUR system. Therefore, compared with the prior art, the present invention has the following beneficial effects:

1. The reactive polyurethane hot melt adhesive of the present invention adds acrylic resin with a higher glass transition temperature, a specific type of adhesion promoter and a latent curing agent, and is combined with a specific isocyanate, and is mixed with an amorphous polyester according to a specific ratio. Alcohol and polyether polyol and other components are prepared together, so that it has the advantages of high transparency, strong initial adhesion, fast curing speed, high final bonding strength, etc., especially suitable for high transparency requirements Field use, has a good market prospect.

2. The reactive polyurethane hot melt adhesive of the present invention is a single-component moisture-curing polyurethane adhesive, which belongs to the solvent-free and environmentally friendly adhesive industry, and can be used for bonding plastic, glass, metal, textile and other substrates.

3. The preparation process of the reactive polyurethane hot melt adhesive of the present invention is simple, easy to operate, and easy to industrialize.

Detailed ways

The technical solutions of the present invention will be further described below through specific examples. It should be clear to those skilled in the art that the examples are only for helping to understand the present invention, and should not be regarded as specific limitations on the present invention.

Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by one of ordinary skill in the technical field of the present invention. Terms used in the description of the present invention are only for the purpose of describing specific embodiments, and are not used to limit the present invention.

The terms "including" and "having" and any variations thereof in the present invention are intended to cover a non-exclusive inclusion. For example, a process, method, device, product or equipment that includes a series of steps is not limited to the listed steps or modules, but optionally also includes steps that are not listed, or optionally also includes for these processes, Other steps inherent in a method, product, or apparatus.

The "plurality" mentioned in the present invention means two or more. "And/or" describes the association relationship of associated objects, indicating that there may be three types of relationships, for example, A and/or B may indicate: A exists alone, A and B exist simultaneously, and B exists independently. The character "/" generally indicates that the contextual objects are an "or" relationship.

7100系列，具体如下： The amorphous polyester polyol that adopts in the embodiment of the present invention and comparative example is purchased from Evonik's

7100 series, as follows:

7130，羟值为31mgKOH/g～39mgKOH/g；

7130, the hydroxyl value is 31mgKOH/g～39mgKOH/g;

7150，羟值在38mgKOH/g～46mgKOH/g。

7150, the hydroxyl value is between 38mgKOH/g and 46mgKOH/g.

Polyoxypropylene glycol (PPG) was purchased from Jiangsu Zhongshan Chemical Co., Ltd., Mn=2000, and the hydroxyl value was 54 mgKOH/g-58 mgKOH/g.

2013、

2016购自英国璐彩特化工有限公司，其中， Acrylic

2013,

2016 was purchased from British Lucite Chemical Co., Ltd., of which,

2013的玻璃化转变温度(Tg)为76℃，Mn＝34000；

The glass transition temperature (Tg) of 2013 is 76°C, Mn=34000;

2016的玻璃化转变温度(Tg)为59℃，Mn＝60000。

The glass transition temperature (Tg) of 2016 is 59°C, Mn=60000.

AC1420，购自赢创公司，其玻璃化转变温度(Tg) 为44℃，Mn＝30000。 Acrylic

AC1420, purchased from Evonik, has a glass transition temperature (Tg) of 44°C and Mn=30000.

RE 100L和萜烯树脂

TR 105购自美国亚利桑那化学公司。 Rosin resin

RE 100L and terpene resin

TR 105 was purchased from Arizona Chemical Company, USA.

Carbodiimide-modified 4,4'-diphenylmethane diisocyanate (MDI) was purchased from Huntsman, USA.

Other raw material components are common commercially available products.

The following are specific examples.

The raw materials used in the embodiments of the present invention and comparative examples are shown in Table 1 below:

Each raw material component and its proportioning ratio (parts by weight) in each embodiment and comparative example of table 1

The preparation method of the reactive polyurethane hot-melt adhesive that embodiment and comparative example provide comprises the following steps:

(1) Put amorphous polyester polyol, polyether polyol, and acrylic resin into the reaction kettle, heat to 120°C, vacuum dehydrate for 120 minutes under stirring, and the vacuum degree is -0.09MPa;

(2) drop in isocyanate, and stir and react at 110° C. for 90 minutes under _N protection;

(3) Put in the latent curing agent, and stir and react at 110°C for 20 minutes under the protection of N ₂ ;

(4) Add adhesion promoter, catalyst, antioxidant, UV absorber successively, and stir and mix at 110 ℃ for 30 minutes under _N protection;

(5) Keep the temperature at 110°C, evacuate until no bubbles appear, and discharge the product.

Effect test:

Get the reactive polyurethane hot-melt adhesive that embodiment 1-3 and comparative example 1-9 make, press the initial tack force of GB/T 7124-2008 test hot-melt adhesive (sample is under the condition of 25 ℃/50%RH The tensile shear strength tested after curing for 3min), the curing speed (the tensile shear strength and the final bonding of the test sample were respectively cured for 2h, 6h, 12h and 24h under the condition of 25°C/50%RH degree), final bond strength (the tensile shear strength of the sample after curing for 7 days at 25°C/50%RH); according to GB/T 2410-2008, test the light transmission of hot melt adhesive rate and haze; according to HG/T 3862-2006, test the yellowing index of hot melt adhesive (PUR cured product is irradiated on xenon lamp aging instrument for 480h). The test results are shown in Table 2.

Table 2 embodiment 1-3 and comparative example 1-9 Reactive polyurethane hot melt adhesive relevant performance test result

As can be seen from the experimental data in Table 2, the highly transparent polyurethane hot-melt adhesive prepared in Examples 1-3 of the present invention has the advantages of high transparency, good yellowing resistance, high initial adhesion, fast curing speed and high final bonding strength. For bonding applications on transparent materials. Among them, the reactive polyurethane hot-melt adhesive in Example 3 obtained the most excellent comprehensive performance under its preferred raw materials and specific proportions.

AC1420代替

2013，其初粘力由原来的0.5变为0.29，初粘强度明显变小；对比例8没有添加潜固化剂，固化速度明显变慢，且最终粘接强度变差，这可能与无潜固化剂的PUR体系湿固化反应较慢，且会释放较多CO ₂，使胶层有气泡产生，导致粘接缺陷所致；对比例9没有添加粘合促进剂，其最终粘接强度较差。可见，本发明的各原料组分按照特定种类和配比配合才能同时获得高透明度、耐黄变性好、初粘力大、固化速度快和最终粘接强度高的综合性能。 As can be seen from the performance comparison of Comparative Examples 1-9 and Example 3, Comparative Examples 1-3 use carbodiimide modified MDI, MDI-50, MDI to replace IPDI respectively, and its yellowing index increases significantly, and the yellowing resistance Denaturation becomes worse; comparative example 4 does not add acrylic resin, and its initial tack becomes 0.18 by original 0.5, and initial tack strength significantly diminishes; Comparative example 5-6 replaces acrylic resin with rosin resin, terpene resin respectively, not only The initial adhesion and final bonding strength have been greatly reduced, and because of its own color, its yellowing index is greater than 8, and a large discoloration has occurred; comparative example 7 uses the Tg lower than 50 ℃

AC1420 instead

In 2013, the initial bonding strength changed from 0.5 to 0.29, and the initial bonding strength was significantly smaller; in Comparative Example 8, no latent curing agent was added, the curing speed was significantly slower, and the final bonding strength became worse, which may be related to no latent curing. The moisture curing reaction of the PUR system of the agent is slow, and it will release more CO ₂ , which will cause air bubbles in the adhesive layer, resulting in bonding defects; Comparative Example 9 does not add an adhesion promoter, and its final bonding strength is poor. It can be seen that the comprehensive properties of high transparency, good yellowing resistance, high initial adhesion, fast curing speed and high final bonding strength can be obtained at the same time when the raw material components of the present invention are combined according to specific types and proportions.

The technical features of the above-mentioned embodiments can be combined arbitrarily. To make the description concise, all possible combinations of the technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, should be considered as within the scope of this specification.

The above-mentioned embodiments only express several implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but should not be construed as limiting the patent scope of the invention. It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be based on the appended claims.

Claims (10)

A highly transparent reactive polyurethane hot-melt adhesive, characterized in that it is prepared from the following raw materials in parts by weight: 20-45 parts of amorphous polyester polyol, 10-50 parts of polyether polyol, and 10-40 parts of isocyanate , 10-30 parts of acrylic resin, 0.2-2.5 parts of adhesion promoter, 0.5-3 parts of latent curing agent, 0.01-0.2 parts of catalyst, 0.5-2 parts of ultraviolet light absorber, 0.5-2 parts of antioxidant; The isocyanate is one or more of cyclohexylmethane diisocyanate, isophorone diisocyanate and hexamethylene diisocyanate; The glass transition temperature of the acrylic resin is greater than 50°C; The adhesion promoter is 3-isocyanate propyl triethoxysilane, 3-isocyanate propyl trimethoxysilane, 3-mercaptopropyl trimethoxysilane and 3-mercaptopropyl triethoxysilane one or more; The latent curing agent is 3-hydroxyethyl-1,3-oxazolidine, 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine, 2-phenyl-3-hydroxyethyl -1,3-oxazolidine, (S)-N-Boc-2,2-dimethyl-4-(2-hydroxyethyl)oxazolidine, 2-isopropyl-N-hydroxyethyl- One or more of oxazolidine and 2,2-dimethyl-N-hydroxyethyl-1,3-oxazolidine. The highly transparent reactive polyurethane hot-melt adhesive according to claim 1, characterized in that it is prepared from the following raw materials in parts by weight: 38-42 parts of amorphous polyester polyol, 25-30 parts of polyether polyol, 12-16 parts of isocyanate, 15-20 parts of acrylic resin, 1.8-2.2 parts of adhesion promoter, 1.8-2.2 parts of latent curing agent, 0.05-0.15 parts of catalyst, 0.7-1.0 parts of ultraviolet light absorber, 1.0-2.0 parts of antioxidant 1.4 servings. The highly transparent reactive polyurethane hot-melt adhesive according to claim 1, characterized in that the glass transition temperature of the acrylic resin is greater than 55°C. The highly transparent reactive polyurethane hot-melt adhesive according to claim 3, characterized in that the glass transition temperature of the acrylic resin is 55°C-80°C. The highly transparent reactive polyurethane hot melt adhesive according to claim 1, wherein the acrylic resin is

2013 and/or

2016. The highly transparent reactive polyurethane hot-melt adhesive according to claim 1, wherein the hydroxyl value of the amorphous polyester polyol is 10mgKOH/g-112mgKOH/g; Preferably, the hydroxyl value of the amorphous polyester polyol is 18 mgKOH/g-60 mgKOH/g; Preferably, the hydroxyl value of the amorphous polyester polyol is 30mgKOH/g-50mgKOH/g; Preferably, the amorphous polyester polyol is

Amorphous polyester polyols of the 7100 series; Preferably, the amorphous polyester polyol is

7130 and/or

7150. The highly transparent reactive polyurethane hot-melt adhesive according to claim 1, wherein said polyether polyol is polyoxypropylene glycol; Preferably, the polyoxypropylene diol has a number average molecular weight of 1800-2200. The highly transparent reactive polyurethane hot-melt adhesive according to claim 1, characterized in that, it is prepared from the following raw materials in parts by weight: amorphous polyester polyol

713039-41 parts, 26-28 parts of polyoxypropylene diol with a number average molecular weight of 2000, 13-15 parts of isophorone diisocyanate, acrylic resin

201317~19 parts, 1.9~2 parts of 3-isocyanate propyl trimethoxysilane, 1.9~2 parts of 3-hydroxyethyl-1,3-oxazolidine, 0.05~0.15 parts of catalyst, 0.7~1.0 parts of ultraviolet light absorber parts, antioxidant 1.0 to 1.4 parts. The highly transparent reactive polyurethane hot-melt adhesive according to any one of claims 1-8, wherein the catalyst is dibutyltin dilaurate, triethylenediamine and dimorpholino diethyl ether. at least one of; and/or, The antioxidant is at least one of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester and 2,6-di-tert-butyl-p-cresol; and / or, The ultraviolet absorber is at least one of UV-123, UV-328, UV-770, UV-928 and UV-1130. A preparation method of heat-resistant reactive polyurethane hot melt adhesive, characterized in that it comprises the following steps: (1) Put the amorphous polyester polyol, polyether polyol, and acrylic resin into a reaction vessel, heat to 100°C-130°C, vacuum dehydrate for 60-180 minutes under stirring, and the vacuum degree is -0.095MPa ~-0.05MPa; (2) Putting in the isocyanate, stirring and reacting at 100°C to 120°C for 60 minutes to 120 minutes under the protection of nitrogen or inert gas; (3) Putting in the latent curing agent, stirring and reacting at 100° C. to 120° C. for 10 minutes to 30 minutes under the protection of nitrogen or inert gas; (4) Add the adhesion promoter, catalyst, antioxidant, and ultraviolet absorber in sequence, and stir and mix at 100° C. to 120° C. for 20 minutes to 40 minutes under the protection of nitrogen or inert gas; (5) Vacuum at 100°C to 120°C until no air bubbles appear, and then discharge.