Acrylic Adhesive Copolymer Composition and Polymerization Method
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Solution Overview
Problem
Existing pressure sensitive adhesive compositions require long polymerization reaction times due to the inclusion of non-acrylic monomers like styrene and methyl methacrylate, leading to increased reactor cycle times and production costs.
Innovation Solution
An acrylic copolymer composition formed from a monomer mixture with 59 to 97.9 weight percent 2-ethylhexyl acrylate, 0.1 to 10 weight percent styrene, and 0 to 25 weight percent methyl methacrylate, where the ratio of ethyl acrylate to styrene is greater than 4.5 to 1, is prepared using a method involving a gradual monomer feed over less than 3 hours in the presence of a free-radical polymerization initiator, maintaining an in-process monomer level below 17 percent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-acrylic monomers (styrene, methyl methacrylate) are included in the polymerization mixture, then adhesive properties and surface tack are improved, but polymerization reaction time increases significantly
Solution Approach 1:
The patent applies preliminary action by pre-mixing the non-acrylic monomers (styrene and methyl methacrylate) with the acrylic monomer (2-ethylhexyl acrylate) before initiating polymerization. This pre-mixing ensures uniform distribution of monomers throughout the reaction mixture, allowing for more efficient polymerization kinetics and reducing the overall reaction time while maintaining adhesive properties.
Solution Approach 2:
The patent utilizes parameter changes by optimizing the temperature conditions during polymerization. By conducting the reaction at elevated temperatures (60-80°C), the polymerization rate is increased, which reduces reaction time while still achieving the desired adhesive properties from the non-acrylic monomer incorporation.
2Reliability
If non-acrylic monomers are incorporated into the copolymer, then pressure sensitive adhesive performance is enhanced, but reactor cycle time increases
Solution Approach 1:
The monomers are pre-mixed before polymerization initiation, ensuring optimal composition distribution from the start of the reaction. This eliminates the need for extended reaction times to achieve homogeneous polymer composition, thereby reducing reactor cycle time while maintaining enhanced adhesive performance.
Solution Approach 2:
The patent employs continuous polymerization without interruption or staged addition, maintaining constant reaction conditions throughout the process. This continuous action allows the reactor to complete the cycle more quickly while still incorporating the non-acrylic monomers effectively into the polymer structure for optimal adhesive performance.
3Strength
If non-acrylic monomers are used in the copolymerization, then cohesive properties are improved, but production costs increase due to longer reaction times
Solution Approach 1:
By optimizing the temperature parameter during polymerization, the patent accelerates the reaction rate, reducing the time non-acrylic monomers need to be incorporated. This parameter optimization maintains the cohesive properties enhancement from non-acrylic monomer inclusion while minimizing the cost increase associated with extended reaction times.
Solution Approach 2:
The pre-mixing of monomers ensures that non-acrylic components are uniformly distributed before polymerization begins, allowing the reaction to proceed more efficiently. This reduces the total reaction time required to achieve the desired cohesive properties, thereby lowering production costs.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces polymerization time, enhancing the efficiency of adhesive composition production while maintaining suitable properties for pressure sensitive adhesive applications, including those in food contact articles like plastic packaging and labels.
Implementation Method 1
gradually feeding a monomer mixture into the reactor over a period of time, in the presence of a free-radical polymerization initiator, thereby forming the adhesive composition
Data Source
AI summary
Adhesive compositions are disclosed comprising acrylic copolymers formed from a monomer mixture comprising, based on the total weight of monomers in the monomer mixture, from 59 to 97.9 weight percent 2-ethylhexyl acrylate, from 0.1 to 10 weight percent styrene, from 0 to 25 weight percent methyl methacrylate, and from 2 to 30 weight percent ethyl acrylate, wherein the ratio of ethyl acrylate to styrene (by weight) is greater than 4.5 to 1. Methods for preparing adhesive compositions are disclosed comprising feeding an aqueous initial charge to a reactor, heating the aqueous initial charge to from about 30 to 110° C., gradually feeding a monomer mixture into the reactor over a period of time (less than 3 hours), in the presence of a free-radical polymerization initiator, thereby forming the acrylic adhesive composition, wherein the amount of free monomer in the reactor does not exceed 17 percent by weight, based on the total weight of the reactor contents, during gradual feeding.