CN112552861A

CN112552861A - Polyether type moisture curing polyurethane hot melt adhesive and preparation method thereof

Info

Publication number: CN112552861A
Application number: CN202011494526.1A
Authority: CN
Inventors: 许磊; 鲍火华
Original assignee: Zhejiang Joya Polymer Technology Co ltd
Current assignee: Zhejiang Joya Polymer Technology Co ltd
Priority date: 2020-12-17
Filing date: 2020-12-17
Publication date: 2021-03-26

Abstract

The invention discloses a polyether type moisture curing polyurethane hot melt adhesive and a preparation method thereof, which adopts the process of firstly adding isocyanate and then adding polyether polyol, uses a polyol material with branching degree, increases the tolerance of the formula to moisture, reduces the vacuum pumping link, can greatly reduce the production cost, not only improves the production efficiency, but also has stable and reliable product quality, the bonding force can reach the level of the polyester type hot melt adhesive, and the bonding force of the hot melt adhesive is good.

Description

Polyether type moisture curing polyurethane hot melt adhesive and preparation method thereof

Technical Field

The invention relates to the technical field of hot melt adhesives, in particular to a polyether type moisture curing polyurethane hot melt adhesive and a preparation method thereof.

Background

The moisture cured polyurethane hot melt adhesive (PUR) is one kind of special environment friendly solvent-free single component polyurethane adhesive, and has isocyanate terminated polyurethane prepolymer with polar and chemically active urethane group (-NHCOO-) or isocyanate group (-NCO) group in the molecular structure. PUR has two processes during use, physical and chemical reactions: the physical reaction is that the hot plastic cold setting property of the common hot melt adhesive is provided, the glue is coated in a high-temperature fluid state, and the temperature is reduced during the lamination and the crystallization is rapidly positioned; the chemical reaction is that the reactive group of the PUR is chemically cross-linked with the moisture in the air and the active hydrogen in the material into the polyurethane high molecular material within about several hours to several days after the application. The PUR does not use any solvent during production and application, is nontoxic and tasteless, does not pollute the environment, is known as a green adhesive, is particularly suitable for being used on a continuous production line, and is widely applied to the fields of fabrics, automobiles, household appliances, woodworkers and the like.

At present, PUR production enterprises all adopt a production process of adding polyol and then adding isocyanate, which requires that the polyol is dehydrated in vacuum before production, namely, polyol components are mixed and then dehydrated at high temperature, then the temperature is reduced and the isocyanate is added, and synthesis reaction is carried out at low temperature, so that the production process is complex and the production efficiency is difficult to improve. The existing polyol vacuum dehydration process has long dehydration time, generally dehydrates for at least 2 hours, has higher temperature, has some influence on small molecules in the dehydration process, can cause unstable formula due to a part of lost small molecules, and can cause unstable bonding quality when a client uses the polyol subsequently. The overall process is complex, the production time is long, the quality is easy to fluctuate, and the customer complaints are more, so that the method is a main problem faced by the conventional PUR production enterprises.

The hot melt adhesive products in the market at present mainly take polyester type or polyether polyester mixed type products as main products, and the reasons are that the polyester type has good initial adhesion and good crystallization and shaping speed, but the feeding is difficult and the hydrolysis resistance is poor. The polyether product mainly has low initial viscosity, easy production and feeding and no need of preheating the material.

Therefore, in order to solve the problems in the prior art, a preparation method of the polyether polyurethane hot melt adhesive needs to be provided.

Disclosure of Invention

The invention aims to solve the technical defects and provide the polyether type moisture curing polyurethane hot melt adhesive and the preparation method thereof, which do not need to pretreat raw materials and improve the production efficiency and the product quality.

In order to achieve the purpose, the polyether type moisture curing polyurethane hot melt adhesive comprises the following components: 14-40 parts of isocyanate, 55-85 parts of first polyether polyol, 0.5-5 parts of second polyether polyol, 0.001-0.04 part of polymerization inhibitor, 0.2-1.5 parts of defoaming agent and 0.02-0.2 part of catalyst, wherein the parts are parts by mass.

The isocyanate refers to a compound having an isocyanate group. Including, but not limited to, Toluene Diisocyanate (TDI), diphenylmethane diisocyanate (MDI), 1, 5-Naphthalene Diisocyanate (NDI), Hexamethylene Diisocyanate (HDI), methylcyclohexyl diisocyanate, 4' -dicyclohexylmethane diisocyanate, isophorone diisocyanate (IPDI), p-phenylene diisocyanate (PPDI), p-phenylene diisocyanate (XDI), tetramethyl dimethylene diisocyanate (TMXDI), and polymers, modified products of such compounds, which may be used alone or in combination. Preferably, the isocyanate is one or more of toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate, and more preferably diphenylmethane diisocyanate.

The first polyether polyol is polyether polyol with the functionality of 2 and the hydroxyl value of 15-600 mgKOH/g. The polyether polyol I is one or more of polyoxypropylene glycol, polyethylene glycol, polytetrahydrofuran ether glycol and tetrahydrofuran-propylene oxide copolymerized glycol; the polyether polyol I comprises high molecular weight polyether polyol and low molecular weight polyether polyol, wherein the hydroxyl value of the high molecular weight polyether polyol is 15-65mgKOH/g, preferably 26-59mgKOH/g, and the hydroxyl value of the low molecular weight polyether polyol is 55-570mgKOH/g, preferably 90-300 mgKOH/g.

The second polyether polyol is polyether polyol with the functionality of 3 and the hydroxyl value of 28-1000 mgKOH/g. The hydroxyl value is preferably 160-560 mgKOH/g. The second polyether polyol can improve the initial viscosity and initial adhesion of the product.

The polymerization inhibitor is an acidic substance which provides active hydrogen. Including but not limited to phosphoric acid, hypophosphorous acid, hydroquinone, erucic acid, benzoic acid, citric acid, and such polymerization inhibitors may be used alone or in combination. Preferably, the polymerization inhibitor is one or more of phosphoric acid, hypophosphorous acid and hydroquinone, more preferably phosphoric acid.

The catalyst includes, but is not limited to, titanate of organic ligand or complex ligand, organic tin compound, bismuth compound, amine substance, morpholine derivative, and such catalysts may be used alone or in combination. Preferably, the catalyst is a morpholine derivative.

The defoaming agent is a compound which has a defoaming effect on the mixture. Including but not limited to liquid formulated products of mineral oils, silicones, polyethers, such defoamers may be used alone or in combination.

Adding isocyanate into a reactor, starting stirring, controlling the temperature of the reactor to be 60-80 ℃, preferably 65-75 ℃, and adding a polymerization inhibitor into the reactor; sequentially adding the first polyether polyol, the second polyether polyol, a catalyst and a defoaming agent into a reactor, controlling the temperature of the reactor to be 75-95 ℃ and preferably 80-90 ℃ to react in the process of adding the raw materials into the reactor, carrying out vacuum defoaming treatment in the reaction process, and discharging qualified materials after reacting for 3 hours.

The components are added into the reactor slowly or in batches. The slow addition of the reactants and the batchwise addition of the reactants are well known operations in the art, with the aim of controlling the reaction process smoothly and preventing excessive reaction temperatures. The invention can control the reaction process and the reaction heat release condition by slowly adding or adding raw materials in batches, and is beneficial to controlling the process parameters, thereby ensuring the product quality to be more stable.

During the process of adding each component into the reactor, the next component can be added at intervals or not after the last component is added, and preferably, the next component is not added at intervals. The interval between the feeding of the upper component and the feeding of the next component into the reactor is not influenced, and the feeding of the next component is preferably not interrupted, so that the production efficiency can be improved.

After all the components are added, the method also comprises a vacuum defoaming step. The defoaming device and the specific operation steps adopted in the vacuum defoaming step are well known in the art, and the purpose is to quickly remove the bubbles in the reaction mixture, reduce the influence of the bubbles on the package, and improve the production efficiency and the product quality.

In order to reduce the influence of moisture in the environment on the formula and the process, nitrogen is required to be used in the whole process, and high-purity nitrogen is also used for gas replacement and emptying in the replacement process in the vacuum operation.

The invention designs a polyether type moisture curing polyurethane hot melt adhesive, which comprises the following raw materials in percentage by mass:

the amount of isocyanate used is 14-40%, preferably 20-35%;

the amount of the first polyether polyol is 55-85%, preferably 60-78%;

the amount of the second polyether polyol is 0.5-5%, preferably 1-4%;

the amount of the polymerization inhibitor is 0.001-0.04%, preferably 0.002-0.01%;

the dosage of the defoaming agent is 0.2 to 1.5 percent, preferably 0.3 to 1 percent;

the amount of catalyst used is 0.02-0.2%, preferably 0.04-0.15%.

In the method, a water removal step is not required for each component, and all raw materials are qualified raw materials meeting the moisture requirement of below 500 ppm. The method can improve the tolerance of the whole reaction process to the water content in the raw materials by limiting each component and controlling the reaction steps, does not need to remove water from the raw materials, and improves the production efficiency.

The raw materials used in the process do not contain polyester polyols. The invention adopts a brand new formula and a production process, adopts polyether which properly increases the cross-linking density and the branching degree among molecules, and adopts polyether with 3 functionality degree to replace polyester substances which are easy to crystallize or have large viscosity, thereby improving the initial adhesion and the final adhesion of the product, greatly improving the dispersibility of the product and ensuring more stable quality.

The method employs a feedstock that does not contain small molecule alcohols. The invention adopts a brand new formula and a production process, does not use micromolecules which are easy to crystallize, and adopts polyether with 3 functionality, thereby improving the initial adhesion and the final adhesion of the product and further meeting the production technical requirements of customers.

The process employs raw materials that do not contain plasticizers or tackifying resins.

The process employs starting materials that do not contain a solvent.

The method does not need to modify organic isocyanate in advance.

The polyether type moisture curing polyurethane hot melt adhesive prepared by the method has higher initial adhesion and final adhesion and proper open time, and can meet the conventional requirements of the field on the moisture curing polyurethane hot melt adhesive; the hot melt adhesive can be applied to bonding of various substrates such as wood, fabrics, plastics, metal, glass and the like, and is particularly suitable for compounding in the fields of cloth-attached cloth and cloth-attached film.

The invention has the beneficial effects that: 1. the technical process comprises the steps of firstly adding isocyanate, then adding other components in sequence, and controlling the reaction activity of each reactant in different stages, so as to control the stability of the whole reaction process, reduce the reaction time and improve the production efficiency;

2. by controlling the process, limiting the types and the dosage of the raw materials and the like, the molecular weight and the distribution of the product are stable, and the product has good initial adhesion and final adhesion and excellent mechanical properties when being bonded with a base material.

Detailed Description

The examples and comparative examples used the following starting materials:

diphenylmethane diisocyanate, MDI-100 or MDI-50, Pasteur Germany;

polyether 1, DL400, functionality of 2, hydroxyl value of 280mgKOH/g, majondong daliang, inc;

polyether 2, DDL1000D, functionality 2, hydroxyl value 112mgKOH/g, Dalanxing, east Shandong;

polyether 3, DDL2000D, functionality 2, hydroxyl number 56mgKOH/g, Daisy, Shandong;

polyether 4, DDL4000D, functionality 2, hydroxyl value 28mgKOH/g, Daisy, Shandong, Inc.;

polyether 5, DV125, functionality of 3, hydroxyl value of 450mgKOH/g, Shandong Dalanxing company;

polyether 6, MN500, functionality 3, hydroxyl value 340mgKOH/g, majondong daliang, inc;

polyether 7, MN700, functionality of 3, hydroxyl value of 240mgKOH/g, great bluestar, shandong;

polyether 8, MN1000, functionality of 3, hydroxyl value of 167mgKOH/g, majondong daliang, inc;

polyether 9, DL200, functionality of 2, hydroxyl value of 560mgKOH/g, majondong daliang, inc;

polyester 1, XCP-1000N, functionality 2, hydroxyl number 110.7mgKOH/g, Asahi Sichuan chemical Co., Ltd;

polyester 2, XCP-244, having a functionality of 2 and a hydroxyl number of 57mgKOH/g, Asahi Sichuan chemical (Suzhou) Co., Ltd.;

phosphoric acid was purchased from san Yi chemical Co., Suzhou;

catalyst, DMDEE, newscast chemicals (shanghai) ltd;

antifoam, BYK-022, Shanghai Guangbai New materials, Inc.

The amounts of the raw materials used in the examples and comparative examples are shown in Table 1.

Example 1

Under the nitrogen atmosphere, MDI-100 is added into a reactor, stirring is started, the reaction temperature is controlled to be 65 ℃, a polymerization inhibitor is added, after uniform stirring, the reactor temperature is controlled to be 85 ℃, polyether, a catalyst and a defoaming agent are sequentially and slowly added for reaction, defoaming treatment is carried out after 120 minutes, the reaction is finished after 60 minutes, the test of NCO content meets the design requirement, and discharging is carried out.

Example 2

Under the nitrogen atmosphere, adding MDI-50 into a reactor, starting stirring, controlling the reaction temperature to be 68 ℃, adding a polymerization inhibitor, uniformly stirring, slowly adding polyether, a catalyst and a defoaming agent in sequence for reaction, controlling the temperature of the reactor to be 86 ℃, carrying out defoaming treatment after 120 minutes, finishing the reaction after 60 minutes, testing the NCO content to meet the design requirement, and discharging.

Example 3

Under the nitrogen atmosphere, MDI-100 is added into a reactor, stirring is started, the reaction temperature is controlled to be 70 ℃, a polymerization inhibitor is added, after uniform stirring, polyether, a catalyst and a defoaming agent are sequentially and slowly added for reaction, the temperature of the reactor is controlled to be 90 ℃, defoaming treatment is carried out after 120 minutes, the reaction is finished after 60 minutes, the test of NCO content meets the design requirement, and discharging is carried out.

Example 4

Under the nitrogen atmosphere, MDI-100 is added into a reactor, stirring is started, the reaction temperature is controlled to be 72 ℃, a polymerization inhibitor is added, after uniform stirring, polyether, a catalyst and a defoaming agent are sequentially and slowly added for reaction, the temperature of the reactor is controlled to be 93 ℃, defoaming treatment is carried out after 120 minutes, the reaction is finished after 60 minutes, the test of NCO content meets the design requirement, and discharging is carried out.

Example 5

Under the nitrogen atmosphere, MDI-100 is added into a reactor, stirring is started, the reaction temperature is controlled to be 75 ℃, a polymerization inhibitor is added, after uniform stirring, polyether, a catalyst and a defoaming agent are sequentially and slowly added for reaction, the temperature of the reactor is controlled to be 95 ℃, defoaming treatment is carried out after 120 minutes, the reaction is finished after 60 minutes, the test of NCO content meets the design requirement, and discharging is carried out.

Comparative example 1

Under the atmosphere of nitrogen, MDI-100 is added into a reactor, stirring is started, the reaction temperature is controlled to be 68 ℃, a polymerization inhibitor is added, after uniform stirring, polyether polyol, a catalyst and a defoaming agent are sequentially and slowly added for reaction, the temperature of the reactor is controlled to be 88 ℃, defoaming treatment is carried out after 120 minutes, the reaction is finished after 60 minutes, the test of NCO content meets the design requirement, and discharging is carried out.

Comparative example 2

Under the nitrogen atmosphere, MDI-100 is added into a reactor, stirring is started, the reaction temperature is controlled to be 65 ℃, a polymerization inhibitor is added, after uniform stirring, polyester polyol, a catalyst and a defoaming agent are sequentially and slowly added for reaction, the temperature of the reactor is controlled to be 85 ℃, defoaming treatment is carried out after 120 minutes, the reaction is finished after 60 minutes, the test of NCO content meets the design requirement, and discharging is carried out.

Comparative example 3

Under the atmosphere of nitrogen, MDI-50 is added into a reactor, stirring is started, the reaction temperature is controlled to be 66 ℃, a polymerization inhibitor is added, after uniform stirring, polyether polyol, a catalyst and a defoaming agent are sequentially and slowly added for reaction, the temperature of the reactor is controlled to be 82 ℃, defoaming treatment is carried out after 120 minutes, the reaction is finished after 60 minutes, the test of NCO content meets the design requirement, and discharging is carried out.

The examples and comparative examples were tested:

initial adhesionThe force test method comprises the following steps: coating was carried out with a 50 μm doctor blade, coating weight 12g/m²Curing for 2 hours at 25 ℃ and 50% humidity, and performing a tensile test;

the final adhesion test method comprises the following steps: coating was carried out with a 50 μm doctor blade, coating weight 12g/m²Curing for 16 hours at 25 ℃ and 50% humidity, and performing a tensile test;

the method for testing the bonding force after washing comprises the following steps: placing a small amount of washing powder into the cured sample at 40 ℃, automatically washing for 5 times by a roller washing machine, and testing the tensile force of the sample for 50 minutes each time;

the tensile test adopts a KINSGEO high-low temperature universal tester, the width of a test sample strip is 50mm, and the speed is 300 mm/min.

The test data for the examples and comparative examples are shown in table 2.

Note: the viscosity is data tested by adopting an NDJ-1C rotational viscometer;

from the test data, the initial adhesion and final adhesion test results of the embodiments 1 to 5 are superior to those of the comparative examples 1 to 3, and the invention can meet the technical requirements of customers on the initial adhesion (the initial adhesion required by the customers is greater than 2.0N/25 mm) and the final adhesion (the final adhesion required by the customers is greater than 4.0N/25 mm).

Claims

1. The utility model provides a polyether type moisture curing polyurethane hot melt adhesive, characterized by: comprises the following components: 14-40 parts of isocyanate, 55-85 parts of first polyether polyol, 0.5-5 parts of second polyether polyol, 0.001-0.04 part of polymerization inhibitor, 0.2-1.5 parts of defoaming agent and 0.02-0.2 part of catalyst, wherein the parts are parts by mass.

2. The polyether type moisture curing polyurethane hot melt adhesive as claimed in claim 1, wherein: the isocyanate refers to a compound having an isocyanate group.

3. The polyether type moisture curing polyurethane hot melt adhesive as claimed in claim 1, wherein: the first polyether polyol is polyether polyol with the functionality of 2 and the hydroxyl value of 15-600 mgKOH/g.

4. The polyether type moisture curing polyurethane hot melt adhesive as claimed in claim 1, wherein: the second polyether polyol is polyether polyol with the functionality of 3 and the hydroxyl value of 28-1000 mgKOH/g.

5. The polyether type moisture curing polyurethane hot melt adhesive as claimed in claim 1, wherein: the polymerization inhibitor is an acidic substance which provides active hydrogen.

6. The polyether type moisture curing polyurethane hot melt adhesive as claimed in claim 1, wherein: the defoaming agent is a compound which has a defoaming effect on the mixture.

7. A method for preparing the polyether type moisture curing polyurethane hot melt adhesive according to any one of claims 1 to 6, which is characterized by comprising the following steps: adding isocyanate into a reactor, starting stirring, controlling the temperature of the reactor to be 60-80 ℃, and adding a polymerization inhibitor into the reactor; sequentially adding the first polyether polyol, the second polyether polyol, a catalyst and a defoaming agent into a reactor, controlling the temperature of the reactor to be 75-95 ℃ in the process of adding the raw materials into the reactor, carrying out vacuum defoaming treatment in the reaction process, reacting for 3 hours, and discharging qualified products.