阅读说明：本技术 一种烘干型无溶剂发泡涂层用pu树脂及其制备方法 (PU resin for drying type solvent-free foaming coating and preparation method thereof ) 是由 舒科进 陈元昌 于 2021-01-15 设计创作，主要内容包括：本发明提供了一种烘干型无溶剂发泡涂层用PU树脂及其制备方法,该PU树脂由下组分构成：多元醇,甲苯二异氰酸酯,甲乙酮肟,发泡胶囊,混合胺交联剂等。本发明通过异氰酸酯过量的方式来制备较小分子量较低粘度的稳定的封闭型预聚体,从而添加混合胺是不会与预聚体产生反应的,保证预聚体与混合胺的混合后的贮存稳定性,使期可以长时间的稳定贮存,方便生产现场的加工使用。制备的PU树脂制作涂层产品拥有非常好的厚实感、柔韧性和Q感,同样涂层产品的成品厚度因其发泡胶囊的发泡效果大大降低了树脂的涂布量,从而也节省了大量的生产成本；同时,整个生产过程中无溶剂的挥发排放,可做到无VOC的产生,对环境的友好起到非常大的作用。(The invention provides a PU resin for a drying type solvent-free foaming coating and a preparation method thereof, wherein the PU resin comprises the following components: polyols, toluene diisocyanate, methyl ethyl ketoxime, foaming capsules, mixed amine crosslinking agents, and the like. The invention prepares the stable closed prepolymer with smaller molecular weight and lower viscosity by the mode of excessive isocyanate, so that the added mixed amine does not react with the prepolymer, the storage stability of the mixed prepolymer and the mixed amine is ensured, the stable storage can be carried out for a long time, and the processing and the use in a production field are convenient. The prepared PU resin prepared coating product has very good thickness, flexibility and Q feeling, and the coating amount of the resin is greatly reduced due to the foaming effect of the foaming capsule of the thickness of the finished product of the coating product, so that a large amount of production cost is saved; meanwhile, the whole production process has no volatile emission of solvent, no VOC is generated, and the method plays a great role in environmental friendliness.)

1. The PU resin for the drying type solvent-free foaming coating is characterized in that: the PU resin for the drying type solvent-free foaming coating comprises the following components in percentage by weight:

polyol: 58-78%, toluene diisocyanate: 10-20%, methyl ethyl ketoxime: 5-12%, modified organic silicon flatting agent: 0.1-1.5%, modified organic silicon defoamer: 0.1-1%, foaming capsule: 0.5-5%, mixed amine crosslinking agent: 1-8%, organic bismuth catalyst: 0.01 to 0.3 percent.

2. The PU resin for drying type solvent-free foaming coating according to claim 1, wherein: the mixed amine crosslinking agent is prepared by blending one or more of isophorone diamine, 2-methyl pentamine, triethylene tetramine, diethylene triamine and 4, 4' -diaminodicyclohexyl methane.

3. The PU resin for drying type solvent-free foaming coating according to claim 1, wherein: the equivalent ratio of triethylene tetramine and isophorone diamine or triethylene tetramine and 2-methyl pentanediamine of the mixed amine cross-linking agent is 1: 1-3: 1.

4. the PU resin for drying type solvent-free foaming coating according to claim 1, wherein: the equivalent ratio of the isophorone diamine and triethylene tetramine or 4, 4' -diaminodicyclohexyl methane and triethylene tetramine of the mixed amine cross-linking agent is 2: 1-5: 1.

5. the PU resin for drying type solvent-free foaming coating according to claim 1, wherein: the equivalent ratio of 2-methylpentamethylenediamine to triethylene tetramine of the mixed amine crosslinking agent is 2: 1-4: 1.

6. The PU resin for drying type solvent-free foaming coating according to claim 1, wherein: the polyol is copolymerized polyol or polypropylene oxide polyol, and the copolymerized polyol is copolymerized by adipic acid and diethylene glycol or copolymerized by one or more of adipic acid, ethylene glycol, diethylene glycol, butanediol, neopentyl glycol and 2-methyl-1, 3-propanediol.

7. The PU resin for drying type solvent-free foaming coating according to claim 1, wherein: the toluene diisocyanate is any one of TDI-80 or TDI-100, the TDI-80 is formed by mixing 2, 4-toluene diisocyanate with the content of 80% and 2, 6-toluene diisocyanate with the content of 20%, and the TDI-100 is made of the 2, 4-toluene diisocyanate with the content of 100%.

8. The PU resin for drying type solvent-free foaming coating according to claim 1, wherein: the ratio of the number of the toluene diisocyanate to the number of the hydroxyl groups is 1.5-3.0.

9. The method for preparing the PU resin for the drying type solvent-free foaming coating as claimed in claim 1, wherein: the preparation method comprises the following steps:

the first step is as follows: firstly, completely adding toluene diisocyanate into a reaction kettle, sequentially adding polyhydric alcohols into the reaction kettle at least ten times according to the sequence, wherein the adding amount of the polyhydric alcohols is the same for each time, and carrying out reaction at the temperature of 46-48 ℃ with the interval time of adding the polyhydric alcohols for each time being 25-35 min;

the second step is that: reacting for 25-35 min after the last polyol is added, measuring the content of toluene diisocyanate in the kettle to be 0.8-8% of a theoretical value, sequentially adding methyl ethyl ketoxime for at least four times according to a sequence, wherein the adding amount of the methyl ethyl ketoxime is the same for each time, controlling the temperature to be 46-48 ℃ and the interval time for each time to be 10-20 min until the content of isocyanate in the kettle is detected to be zero;

the third step: adding a modified organic silicon flatting agent, a modified organic silicon defoaming agent, a foaming capsule, a mixed amine crosslinking agent and an organic bismuth catalyst, stirring, keeping the temperature at 46-48 ℃, reacting for 25-35 min, and finally discharging and subpackaging to obtain the required product.

Technical Field

The disclosed embodiments of the present invention generally relate to the field of PU resins, and more particularly, to a PU resin for a drying type solvent-free foamed coating and a preparation method thereof.

Background

At present, most of PU foaming resins are mainly two-component foaming resins, aqueous mechanical foaming resins and common foaming resins. PU resins prepared by using a mechanical foaming method or using a traditional physical foaming agent or a traditional chemical foaming agent have various performance defects, and the cell structures of all parts are uneven, so that the performances of all parts are uneven; the open pore ratio is high, so that the foam has good thermal conductivity and poor thermal insulation performance; the cells are unevenly distributed, stress concentration points are easily generated, and the compressive strength is small.

Most of the PU foaming resin adopts A, B two-component foaming products, the processing time is about 1-3 min, and special production equipment such as a mixed foaming machine table is needed. The foaming mechanism of the foaming product is caused by the fact that carbon dioxide gas is generated through the reaction of NCO and water, the foaming multiplying power of the foaming product is related to the instant gas forming amount, and the foaming performance of the foaming product is unstable. For the aqueous mechanical foaming resin, a mechanical stirring mode is adopted to thicken viscosity and simultaneously make air enter the resin to generate a foaming effect, so that the resin has poor film forming property, insufficient toughness strength of the film and poor product quality. The common foaming resin cannot meet the requirement of no VOC or low VOC emission because of containing a solvent, so the common foaming resin is slowly eliminated.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides the PU resin for the drying type solvent-free foamed coating and the preparation method thereof, and the preparation method and the PU resin for the drying type solvent-free foamed coating prepared according to the proportion can effectively solve the problems in the prior art.

The technical scheme of the invention is as follows:

the PU resin for the drying type solvent-free foaming coating comprises the following components in percentage by weight:

polyol: 58-78%, toluene diisocyanate: 10-20%, methyl ethyl ketoxime: 5-12%, modified organic silicon flatting agent: 0.1-1.5%, modified organic silicon defoamer: 0.1-1%, foaming capsule: 0.5-5%, mixed amine crosslinking agent: 1-8%, organic bismuth catalyst: 0.01 to 0.3 percent.

Preferably, the mixed amine crosslinking agent is prepared by blending one or more of isophorone diamine, 2-methyl pentamethylene diamine, triethylene tetramine, diethylene triamine and 4, 4' -diaminodicyclohexyl methane.

Preferably, the equivalent ratio of triethylene tetramine to isophorone diamine or triethylene tetramine to 2-methylpentanediamine of the mixed amine crosslinking agent is 1: 1-3: 1.

preferably, the equivalent ratio of isophorone diamine and triethylene tetramine or 4, 4' -diaminodicyclohexyl methane to triethylene tetramine of the mixed amine crosslinking agent is 2: 1-5: 1.

preferably, the equivalent ratio of 2-methylpentamethylenediamine to triethylene tetramine of the mixed amine crosslinking agent is 2: 1-4: 1.

Preferably, the polyol is a copolymer polyol or polypropylene oxide polyol, and the copolymer polyol is produced by copolymerizing adipic acid and diethylene glycol or copolymerizing adipic acid and one or more of ethylene glycol, diethylene glycol, butanediol, neopentyl glycol and 2-methyl-1, 3-propanediol.

Preferably, the toluene diisocyanate is any one of TDI-80 or TDI-100, the TDI-80 is formed by mixing 2, 4-toluene diisocyanate with the content of 80% and 2, 6-toluene diisocyanate with the content of 20%, and the TDI-100 is made of 2, 4-toluene diisocyanate with the content of 100%.

Preferably, the ratio of the number of the toluene diisocyanate to the number of the hydroxyl groups is 1.5-3.0.

Further, the present invention also provides: a preparation method of PU resin for a drying type solvent-free foaming coating comprises the following steps:

the first step is as follows: firstly, completely adding toluene diisocyanate into a reaction kettle, sequentially adding polyhydric alcohols into the reaction kettle at least ten times according to the sequence, wherein the adding amount of the polyhydric alcohols is the same for each time, and carrying out reaction at the temperature of 46-48 ℃ with the interval time of adding the polyhydric alcohols for each time being 25-35 min;

the second step is that: reacting for 25-35 min after the last polyol is added, measuring the content of toluene diisocyanate in the kettle to be 0.8-8% of a theoretical value, sequentially adding methyl ethyl ketoxime for at least four times according to a sequence, wherein the adding amount of the methyl ethyl ketoxime is the same for each time, controlling the temperature to be 46-48 ℃ and the interval time for each time to be 10-20 min until the content of isocyanate in the kettle is detected to be zero;

the third step: adding a modified organic silicon flatting agent, a modified organic silicon defoaming agent, a foaming capsule, a mixed amine crosslinking agent and an organic bismuth catalyst, stirring, keeping the temperature at 46-48 ℃, reacting for 25-35 min, and finally discharging and subpackaging to obtain the required product.

The invention has the advantages that:

(1) in the process of PU resin polymerization, the prepolymer with smaller molecular weight is prepared by adopting an excessive isocyanate mode, and the isocyanate remained at the tail end of the prepolymer is sealed by using a sealing agent, so that the stable prepolymer with lower viscosity can be prepared, the processing viscosity can be obtained by reducing the viscosity of a prepolymer system without adding a solvent, and the advantages of no solvent and environmental protection are achieved in production.

(2) When the PU resin for the drying type solvent-free foaming coating prepared by the invention is used and the temperature of an oven is regulated and controlled within a range of 120-150 ℃, the prepolymer isocyanate starts to be deblocked slowly because the deblocking temperature of the prepolymer isocyanate is 125-150 ℃. The deblocked isocyanate and the mixed amine react to continuously polymerize into a large molecule of polyurethane product, so that the polyurethane resin obtains excellent physical property and film-forming property. The catalyst can reduce the deblocking temperature to improve the reaction speed of isocyanate and mixed amine, thereby improving the production efficiency in the production and use processes. In addition, because the terminal isocyanate is blocked, the mixed amine does not react with the prepolymer when being added in the process of normal temperature storage (generally, the ambient temperature is lower than 40 ℃), so the storage stability of the mixed prepolymer and the mixed amine is ensured, the mixed prepolymer and the mixed amine can be stably stored for a long time, and the processing and the use in a production field are convenient.

(3) The invention adds microcapsule foaming agent which can fully foam in 120-150 ℃, isocyanate sealed in the temperature interval starts to be deblocked and starts to react with mixed amine, prepolymer slowly changes into a large-component product from a small component and the physical and chemical properties of the resin are formed, the viscosity of the resin is changed from low to high, the surface of a coating changes from wet adhesion to dry and comfortable (before the process, the prepolymer has a process of heating to 120-150 ℃ in an oven, the viscosity of the prepolymer is rapidly reduced due to the heating, the lower viscosity of the prepolymer is beneficial to eliminating steam bubbles brought in the processing and improving the leveling property of the prepolymer, and the system viscosity starts to accelerate the rising until the blocked isocyanate starts to be deblocked and reacts with the mixed amine). At the moment, the foaming capsules start to foam synchronously, the foaming capsules have sufficient foaming space when the resin is at low viscosity, and the foaming of the foaming capsules is finished when the resin reaches a high molecular weight product to form a film. The foaming multiplying power of the foaming capsule can be fully displayed, and the wrapping effect of the resin on the foaming capsule is also ensured. Thereby obtaining an excellent PU resin for foam coating, and the coating resin is coated to make the coating product have very good thick feeling, flexibility and Q feeling. The thickness of the finished product of the coating product greatly reduces the coating amount of the resin due to the foaming effect of the foaming capsule, thereby saving a large amount of production cost. Meanwhile, the whole production process has no volatile emission of solvent, no VOC can be generated, and the method plays a very great role in environmental friendliness.

(4) The reactivity of the diisocyanates of toluene diisocyanate in the present invention is very different due to steric hindrance. The reaction temperature is controlled to be 46-48 ℃, hydroxyl of the polyol can be orderly reacted with the isocyanate on the 4-position of the toluene diisocyanate, and the polyol is added in batches, so that the reaction rate can be controlled, the rapid increase of the reaction temperature caused by the excessive reaction heat release can be prevented, the reaction temperature can be better controlled, the reaction molecular weight can be uniform, and the viscosity of a reaction system is low. The reaction rate of the ortho-isocyanate with methyl ethyl ketoxime may be relatively slow without the exotherm being too rapid to allow better control of the reaction polymerisation.

Detailed Description

Example 1

The PU resin for the drying type solvent-free foaming coating comprises the following components in percentage by weight:

adipic acid copolymerized with diethylene glycol polyol: 58%, toluene diisocyanate: 14.2%, methyl ethyl ketoxime: 12%, modified organosilicon leveling agent: 1.5%, modified silicone defoamer: 1%, foaming capsule: 5%, mixed amine crosslinking agent: 8%, organobismuth catalyst: 0.3 percent.

A preparation method of PU resin for a drying type solvent-free foaming coating comprises the following steps:

the first step is as follows: firstly, completely adding toluene diisocyanate into a reaction kettle, sequentially adding polyhydric alcohols into the reaction kettle for ten times according to the sequence, wherein the adding amount of the polyhydric alcohols is the same for each time, and keeping the temperature at 46 ℃ for reaction with the interval time of each adding being 35 min;

the second step is that: reacting for 35min after the last polyol is added, measuring the content of toluene diisocyanate in the kettle to be 0.8% of a theoretical value, sequentially adding methyl ethyl ketoxime for four times according to the sequence, controlling the temperature to be 46 ℃ and the interval time to be 20min each time until the content of isocyanate in the kettle is detected to be zero;

the third step: adding the modified organic silicon flatting agent, the modified organic silicon defoaming agent, the foaming capsule, the mixed amine crosslinking agent and the organic bismuth catalyst, stirring, keeping the temperature at 46 ℃, reacting for 35min, and finally discharging and subpackaging to obtain the required product.

Example 2

The PU resin for the drying type solvent-free foaming coating comprises the following components in percentage by weight:

adipic acid copolymerized with diethylene glycol polyol: 78%, toluene diisocyanate: 15.29%, methyl ethyl ketoxime: 5 percent, modified organic silicon flatting agent: 0.1%, modified silicone defoamer: 0.1%, foaming capsule: 0.5%, mixed amine crosslinking agent: 1%, organobismuth catalyst: 0.01 percent.

A preparation method of PU resin for a drying type solvent-free foaming coating comprises the following steps:

the first step is as follows: firstly, adding toluene diisocyanate into a reaction kettle, sequentially adding polyol into the reaction kettle for ten times according to the sequence, wherein the adding amount of the polyol is the same for each time, and keeping the temperature at 48 ℃ for reaction, wherein the adding interval time is 25min for each time;

the second step is that: reacting for 25min after the last polyol is added, measuring the content of toluene diisocyanate in the kettle to be 0.8% of a theoretical value, sequentially adding methyl ethyl ketoxime for four times according to the sequence, controlling the temperature to be 48 ℃ and the interval time to be 10min each time until the content of isocyanate in the kettle is detected to be zero;

the third step: adding the modified organic silicon flatting agent, the modified organic silicon defoaming agent, the foaming capsule, the mixed amine crosslinking agent and the organic bismuth catalyst, stirring, keeping the temperature at 48 ℃, reacting for 25min, and finally discharging and subpackaging to obtain the required product.

Example 3

The PU resin for the drying type solvent-free foaming coating comprises the following components in percentage by weight:

adipic acid copolymerized with diethylene glycol polyol: 68.4%, toluene diisocyanate: 14.8%, methyl ethyl ketoxime: 8.9 percent, modified organic silicon flatting agent: 0.5%, modified silicone defoamer: 0.2%, foaming capsule: 2.9%, mixed amine crosslinker: 4.2%, organobismuth catalyst: 0.1 percent.

A preparation method of PU resin for a drying type solvent-free foaming coating comprises the following steps:

the first step is as follows: firstly, adding toluene diisocyanate into a reaction kettle, sequentially adding polyol into the reaction kettle for ten times according to the sequence, wherein the adding amount of the polyol is the same for each time, and keeping the temperature at 47 ℃ for reaction, wherein the adding interval time is 30min for each time;

the second step is that: reacting for 30min after the last polyol is added, measuring the content of toluene diisocyanate in the kettle to be 0.8% of a theoretical value, sequentially adding methyl ethyl ketoxime for four times according to the sequence, controlling the temperature to be 47 ℃ and the interval time to be 15min each time until the content of isocyanate in the kettle is detected to be zero;

the third step: adding the modified organic silicon flatting agent, the modified organic silicon defoaming agent, the foaming capsule, the mixed amine crosslinking agent and the organic bismuth catalyst, stirring, keeping the temperature at 47 ℃, reacting for 30min, and finally discharging and subpackaging to obtain the required product.

Example 4

The PU resin for the drying type solvent-free foaming coating comprises the following components in percentage by weight:

adipic acid copolymerized with diethylene glycol polyol: 60%, toluene diisocyanate: 18.3%, methyl ethyl ketoxime: 10 percent, modified organic silicon flatting agent: 1%, modified silicone defoamer: 0.5%, foaming capsule: 4%, mixed amine crosslinking agent: 6%, organobismuth catalyst: 0.2 percent.

A preparation method of PU resin for a drying type solvent-free foaming coating comprises the following steps:

the first step is as follows: firstly, adding toluene diisocyanate into a reaction kettle, sequentially adding polyol into the reaction kettle for ten times according to the sequence, wherein the adding amount of the polyol is the same for each time, and keeping the temperature at 47 ℃ for reaction, wherein the adding interval time is 30min for each time;

the second step is that: reacting for 30min after the last polyol is added, measuring the content of toluene diisocyanate in the kettle to be 0.8% of a theoretical value, sequentially adding methyl ethyl ketoxime for four times according to the sequence, controlling the temperature to be 47 ℃ and the interval time to be 15min each time until the content of isocyanate in the kettle is detected to be zero;

the third step: adding the modified organic silicon flatting agent, the modified organic silicon defoaming agent, the foaming capsule, the mixed amine crosslinking agent and the organic bismuth catalyst, stirring, keeping the temperature at 47 ℃, reacting for 30min, and finally discharging and subpackaging to obtain the required product.

In order to make the objects, technical solutions and advantages of the embodiments of the present disclosure more clear, the technical solutions in the embodiments of the present disclosure are clearly and completely described, and it is obvious that the described embodiments are a part of the embodiments of the present disclosure, but not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.