Solvent-free adhesive with high initial adhesion and preparation method thereof

Abstract

The invention discloses a high-initial-adhesion solvent-free adhesive and a preparation method thereof. The high-initial-adhesion solvent-free adhesive comprises a component A and a component B, the component A is prepared from the following components in parts by weight: 15 to 40 parts of polyester polyol and 60 to 85 parts of isocyanate; the component B is prepared from the following components in parts by weight: 85 to 95 parts of polyester polyol, 0.01 to 0.1 part of a heat activation catalyst, 0.01 to 0.1 part of a heat sensitive catalyst and 0.2 to 1.2 parts of auxiliaries such as a flatting agent. According to the invention, by accurately controlling the usage amount of more than two thermal activation type and heat sensitive catalysts in the components of the polyester polyol and selecting a proper catalyst active decomposition temperature, the isocyanate and the polyol are finally subjected to multi-step reaction, so that not only can higher initial adhesion be obtained, but also the performance requirements of each stage of the product can be met, and finally, the high initial adhesion requirement is met; and the problems of low product transparency, bubble generation, low peel strength and the like caused by too fast initial reaction and slow later reaction of the product can be prevented.

Description

Technical Field

[0001] The invention relates to the technical field of solvent-free adhesives, in particular to a high initial tack solvent-free adhesive and a preparation method thereof. Background Art

[0002] Solvent-free adhesives can meet the requirements of dry lamination between most flexible packaging materials. They can be used conventionally on solvent-based dry laminating machines, and can also be coated and laminated at high speed on new all-in-one multifunctional solvent-free laminating equipment. At the same time, due to their outstanding advantages in environment, safety, product quality improvement, production efficiency improvement, and overall cost reduction, they bring stronger competitiveness and better opportunities to enterprises, and finally make solvent-free adhesives rapidly popularized and occupy most of the adhesive market.

[0003] The solvent-free adhesive is mainly composed of two components: A (mainly curing agent) and B (polyester polyol, additives, etc.). During use, at a specified temperature, the two components are fully mixed in a certain proportion with a special glue mixer, and then used for bonding more than two layers of flexible packaging films. Finally, the composite materials are placed in a required temperature aging room for aging to achieve the composite performance requirements. It is used for bonding more than two layers of flexible packaging films.

[0004] At present, solvent-free adhesives have strong technical advantages: no drying oven is required, which can save a lot of energy. The amount of glue applied is also lower than other types of adhesives, and the comprehensive cost is reduced by 30-40%. Solvent-free adhesives do not need to emit any gas during use, which makes a great contribution to the improvement of environmental pollution and complies with the country's environmental protection policies. At the same time, it saves the high cost of installing waste gas treatment devices for traditional solvent adhesives, further reducing production costs. Compared with traditional solvent adhesives, it reduces the safety hazards of using day-burning and explosives, and there is no solvent residue in the composite film, ensuring that the packaging products are safer and more hygienic. Solvent-free adhesives have little effect on the products of the previous and next processes. For example: the printing surface ink will not be affected by the quality of ink dissolution due to the use of solvent-based adhesives in the composite process, and the composite process will not cause deformation of the substrate due to the use of solvent-based adhesives and heating, which will affect the production of the subsequent processes. Therefore, solvent-free adhesives are widely used.

[0005] Although solvent-free adhesives have strong technical advantages, they also have some performance deficiencies, such as the common problem of low initial adhesion after lamination. While improving initial adhesion, new problems arise, such as: too fast curing reaction of components A and B leads to unstable product performance, bubbles, reduced transparency, and lamination operation time. Summary of the invention

[0006] In order to solve the above problems in the prior art, the present invention provides a solvent-free adhesive with high initial tack and a preparation method thereof.

[0007] The technical solution adopted by the present invention to solve its technical problem is: A solvent-free adhesive with high initial adhesion comprises component A and component B; the component A comprises 15-40 parts of polyester polyol and 60-85 parts of isocyanate; the component B comprises 85-95 parts of polyester polyol, 0.01-0.1 parts of heat-activated catalyst, 0.01-0.1 parts of heat-sensitive catalyst, and 0.2-1.2 parts of auxiliary agents such as leveling agent.

[0008] A method for preparing a solvent-free adhesive with high initial tack: Step 1: The preparation method of component A comprises: Step 1: Add polyester polyol into the reactor, raise the temperature to 115°C, and keep the vacuum degree below -0.095MPa for 2 hours; Step 2: Add isocyanate quickly, keeping the temperature below 70℃ during the whole process; Step 3: gradually raise the temperature to 80±2℃ for reaction, keep it for 2 hours, measure the NCO content and after it is qualified, quickly cool it down to below 60℃; Step 4: Vacuum degassing, filter the material with a filter, and package to obtain component A; Step 2: The preparation method of component B comprises: Step 1: Add polyester polyol into the reactor, heat it to 115°C, and keep the vacuum degree below -0.095MPa for 2 hours; Step 2: Add heat activated catalyst, heat sensitive catalyst and leveling agent; Step 3: gradually raise the temperature to 80±2℃ for reaction, keep it for 2 hours, and then quickly lower the temperature to below 60℃; Step 4: Vacuum degassing, filter the material with a filter, and package to obtain component B; Step 3: Take ** parts of component A prepared in step 1 and ** parts of component B prepared in step 2, mix and stir to form a solvent-free adhesive with high initial tack.

[0009] The present invention also has the following additional technical features: As a further specific optimization of the technical solution of the present invention: the ratio of the component A to the component B is 100:65-85 parts.

[0010] As a further specific optimization of the technical solution of the present invention: the components of component A are 30 parts of polyester polyol and 70 parts of isocyanate.

[0011] As a further specific optimization of the technical solution of the present invention: the components of component B are 90 parts of polyester polyol, 0.05 parts of thermally activated catalyst, 0.05 parts of thermosensitive catalyst, and 0.8 parts of auxiliary agents such as leveling agent.

[0012] As a further specific optimization of the technical solution of the present invention: Step 1: The preparation method of component A includes: the first step: adding 15-40 parts of polyester polyol into the reaction kettle, heating to 115°C, and achieving a vacuum degree of less than -0.095MPa for 2 hours; the second step: quickly adding 60-85 parts of isocyanate, and the temperature is kept below 70°C during the whole process; the third step: gradually heating to 80±2°C for reaction, maintaining for 2 hours and measuring the NCO content after it is qualified, and then quickly cooling to below 60°C; the fourth step: vacuum degassing for 30 minutes, filtering the material with a filter, and packaging to obtain component A.

[0013] As a further specific optimization of the technical solution of the present invention: Step 2: The preparation method of component B includes: The first step: put 85-95 parts of polyester polyol into the reactor, heat it to 115°C, and keep the vacuum degree below -0.095MPa for 2 hours; the second step: add 0.01-0.1 parts of thermally activated catalyst, 0.01-0.1 parts of thermosensitive catalyst, and 0.2-1.2 parts of leveling agent; the third step: gradually heat it to 80±2°C for reaction, keep it for 2 hours, and then quickly cool it to below 60°C; the fourth step: vacuum degassing for 30 minutes, filter the material with a filter, and package it to obtain component B.

[0014] The present invention precisely controls the usage of two or more heat-activated and heat-sensitive catalysts in the polyester polyol component, selects a suitable catalyst active decomposition temperature, and finally allows the isocyanate and the polyol to react in multiple steps, thereby obtaining a relatively high initial adhesion and meeting the performance requirements of the product at each stage, and finally meeting the high initial adhesion requirements, while preventing problems such as low product transparency, bubble generation, and low peel strength caused by excessively fast initial reaction and slow later reaction. Compared with the prior art, the present invention has the following advantages: Advantages 1. The present invention solves the problem of low initial adhesion of composite products after leaving the machine; Advantage 2. The present invention can prevent problems such as low product transparency, bubble generation, low peeling strength, etc. caused by too fast initial reaction and slow later reaction of the product while ensuring high initial adhesion.

[0015] Advantage 3. Since the present invention can quantitatively control the early curing reaction rate and reaction amount, the composite operation time is extended, thereby increasing the life of the rubber disc. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the performance of a single catalyst binder before improvement of the present invention; Figure 2 It is a schematic diagram of the performance of the improved composite catalyst binder of the present invention. DETAILED DESCRIPTION

[0017] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings.

[0018] A solvent-free adhesive with high initial adhesion comprises component A and component B; the component A comprises 15-40 parts of polyester polyol and 60-85 parts of isocyanate; the component B comprises 85-95 parts of polyester polyol, 0.01-0.1 parts of heat-activated catalyst, 0.01-0.1 parts of heat-sensitive catalyst, and 0.2-1.2 parts of auxiliary agents such as leveling agent.

[0019] A method for preparing a solvent-free adhesive with high initial tack, Step 1: The preparation method of component A comprises: Step 1: Add 15-40 parts of polyester polyol into the reactor, heat it to 115°C (turn on the vacuum at the same time), and keep the vacuum degree below -0.095MPa for 2 hours; Step 2: Quickly add 60-85 parts of isocyanate, and keep the temperature below 70°C during the whole process; Step 3: Gradually raise the temperature to 80±2℃ for reaction. Keep it for 2 hours and measure the NCO content. After it is qualified, quickly cool it down to below 60℃.

[0020] Step 4: Vacuum degassing for 30 minutes, filter the material with a filter net, and package to obtain component A.

[0021] Step 2: The preparation method of component B comprises: Step 1: Add 85-95 parts of polyester polyol into the reactor, heat it to 115°C (turn on the vacuum at the same time), and keep the vacuum degree below -0.095MPa for 2 hours; Step 2: Add 0.01-0.1 parts of heat-activated catalyst, 0.01-0.1 parts of heat-sensitive catalyst, and 0.2-1.2 parts of leveling agent and other additives; Step 3: Gradually raise the temperature to 80±2℃ for reaction, maintain for 2 hours, and then quickly cool down to below 60℃.

[0022] Step 4: Vacuum degassing for 30 minutes, filter the material with a filter net, and package to obtain component B.

[0023] Step 3: Take 100 parts of component A prepared in step 1 and 65-85 parts of component B prepared in step 2, mix and stir to form a solvent-free adhesive with high initial tack. Example

[0024] The ratio of the component A to the component B is 100:75.

[0025] The components of component A are 30 parts of polyester polyol and 70 parts of isocyanate.

[0026] The components of component B are 90 parts of polyester polyol, 0.05 parts of heat-activated catalyst, 0.05 parts of heat-sensitive catalyst, and 0.8 parts of auxiliary agents such as leveling agent.

[0027] 3MDP810 two-component acrylic adhesive purchased on the market.

[0028] Performance comparison between Example 1 and Comparative Example Through a large number of experimental verifications, more than two environmentally friendly heat-activated and heat-sensitive catalysts are quantitatively added to the product. During compounding, the compounding operating temperature is set to the activation temperature A℃ of the heat-activated catalyst. The catalyst begins to decompose during the compounding process, promoting the reaction of catalytic isocyanate and polyol, and forming a higher initial adhesion when it comes off the machine.

[0029] Figure 1 As shown, before the improvement, the single catalyst has the following characteristics: low initial viscosity, low initial adhesion, and fast increase in curing rate.

[0030] Figure 2 As shown, after the improvement, the composite catalyst has: improved viscosity in the early stage, higher initial adhesion, slow curing rate, long operation time, and the curing rate is adjusted in stages in the middle and late stages to ensure stable product performance.

[0031] Since the isocyanate and polyol have undergone initial reaction and are basically completed during the compounding period, although a high initial adhesion is obtained, further reaction is still required to reach the final performance requirements of the product. At this time, the environmentally friendly heat-sensitive catalyst in the product has not yet reached the activation temperature, which can effectively prevent problems such as blistering caused by excessive reaction. After the thermally active catalyst is consumed, the composite product with a high initial adhesion is placed in the set aging chamber, and the temperature is set to B℃. At this time, more than one heat-sensitive catalyst begins to decompose in small amounts, prompting the isocyanate and polyol to further react to ensure that the product performance is steadily improved. After the catalytic effect is basically completed at B℃, the aging temperature is raised to C℃ to further promote the decomposition of the active components of the catalyst, thereby prompting the remaining isocyanate and polyol to react smoothly.

[0032] The above detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention but merely represents selected embodiments of the present invention.

Claims

1. A solvent-free adhesive with high initial tack, characterized in that: The invention comprises component A and component B; the component A comprises 15-40 parts of polyester polyol and 60-85 parts of isocyanate; the component B comprises 85-95 parts of polyester polyol, 0.01-0.1 parts of thermally activated catalyst, 0.01-0.1 parts of thermosensitive catalyst, and 0.2-1.2 parts of auxiliary agents such as leveling agent.

2. The high initial tack solvent-free adhesive according to claim 1, characterized in that: The ratio of the component A to the component B is 100:65-85.

3. The high initial tack solvent-free adhesive according to claim 1, characterized in that: The components of component A are 30 parts of polyester polyol and 70 parts of isocyanate.

4. The high initial tack solvent-free adhesive according to claim 1, characterized in that: The components of component B are 90 parts of polyester polyol, 0.05 parts of heat-activated catalyst, 0.05 parts of heat-sensitive catalyst, and 0.8 parts of auxiliary agents such as leveling agent.

5. A method for preparing a solvent-free adhesive with high initial tack, characterized in that: Step 1: The preparation method of component A comprises: Step 1: Add polyester polyol into the reactor, raise the temperature to 115°C, and keep the vacuum degree below -0.095MPa for 2 hours; Step 2: Add isocyanate quickly, keeping the temperature below 70℃ during the whole process; Step 3: gradually raise the temperature to 80±2℃ for reaction, keep it for 2 hours, measure the NCO content and after it is qualified, quickly cool it down to below 60℃; Step 4: Vacuum degassing, filter the material with a filter, and package to obtain component A; Step 2: The preparation method of component B comprises: Step 1: Add polyester polyol into the reactor, heat it to 115°C, and keep the vacuum degree below -0.095MPa for 2 hours; Step 2: Add heat activated catalyst, heat sensitive catalyst and leveling agent; Step 3: gradually raise the temperature to 80±2℃ for reaction, keep it for 2 hours, and then quickly lower the temperature to below 60℃; Step 4: Vacuum degassing, filter the material with a filter, and package to obtain component B; Step 3: Take ** parts of component A prepared in step 1 and ** parts of component B prepared in step 2, mix and stir to form a solvent-free adhesive with high initial tack.

6. The high initial tack solvent-free adhesive and preparation method thereof according to claim 5, characterized in that: Step 1: The preparation method of component A comprises: Step 1: Add 15-40 parts of polyester polyol into the reactor, raise the temperature to 115°C, and keep the vacuum degree below -0.095MPa for 2 hours; Step 2: Quickly add 60-85 parts of isocyanate, and keep the temperature below 70°C during the whole process; Step 3: gradually raise the temperature to 80±2℃ for reaction, keep it for 2 hours, measure the NCO content and after it is qualified, quickly cool it down to below 60℃; Step 4: Vacuum degassing for 30 minutes, filter the material with a filter net, and package to obtain component A.

7. The high initial tack solvent-free adhesive and preparation method thereof according to claim 5, characterized in that: Step 2: The preparation method of component B comprises: Step 1: Add 85-95 parts of polyester polyol into the reactor, heat to 115°C, and keep the vacuum degree below -0.095MPa for 2 hours; Step 2: Add 0.01-0.1 parts of heat activated catalyst, 0.01-0.1 parts of heat sensitive catalyst, and 0.2-1.2 parts of leveling agent; Step 3: gradually raise the temperature to 80±2℃ for reaction, keep it for 2 hours, and then quickly lower the temperature to below 60℃; Step 4: Vacuum degassing for 30 minutes, filter the material with a filter net, and package to obtain component B.

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