Cold-Seal Adhesive Emulsion Polymer for Recloseable Packaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current cold-sealable packaging compositions based on natural rubber or synthetic polymers fail to achieve desired seal seam strength, blocking resistance, and reclosure forces, and are limited by allergenic potential and organic solvent usage.
Innovation Solution
A resealable packaging with a cold-sealed adhesive layer containing an emulsion polymer made from at least 60% of specific monomers, such as C1-20 alkyl (meth)acrylates, vinyl esters, and vinyl aromatics, produced by emulsion polymerization in the presence of a protective colloid, which forms a self-adhesive and block-resistant coating without organic solvents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If natural rubber latex or synthetic polymers are used for cold seal adhesives, then cold sealability is achieved, but allergenic potential and quality volatility increase
Solution Approach 1:
The patent replaces natural rubber latex with synthetic polymer dispersions that are free from allergenic properties. The synthetic polymers (acrylates, vinyl esters, vinyl aromatics) provide consistent quality without the natural fluctuations and allergen risks associated with natural rubber, effectively substituting a problematic material with a safer alternative.
Solution Approach 2:
The patent uses composite polymer formulations containing multiple monomer types (alkyl (meth)acrylates, vinyl esters, vinyl aromatics, ethylenically unsaturated nitriles, vinyl halides, vinyl ethers, and aliphatic hydrocarbons) to achieve the desired balance of cold sealability, blocking resistance, and reclosure forces while maintaining safety and consistency.
2Reliability
If natural rubber or synthetic polymer dispersions are used, then cold sealability is achieved, but reclosure forces decrease after multiple openings
Solution Approach 1:
The patent optimizes the glass transition temperature parameter of the polymer dispersion to be in the range of -50 to -100°C, which is lower than conventional polymers. This parameter change enables the adhesive to maintain sufficient reclosure forces even after multiple package openings and reclosings, while still achieving effective cold sealability.
Solution Approach 2:
The patent creates different functional zones within the adhesive layer: the polymer matrix provides cold sealability and adhesion, while the incorporated plasticizers and specific monomer compositions provide enhanced flexibility and sustained reclosure forces. This local differentiation of material properties allows simultaneous achievement of multiple performance requirements.
3Reliability
If conventional polymer dispersions are used, then cold sealability is achieved, but blocking resistance against release coating decreases
Solution Approach 1:
The patent adjusts the glass transition temperature parameter to a specific range (-50 to -100°C) and controls the molecular weight and composition of the polymer dispersion to optimize the balance between cold seal adhesion and blocking resistance. This parameter optimization ensures the adhesive bonds strongly during sealing but resists unwanted adhesion to release coatings.
Solution Approach 2:
The patent formulates the adhesive with specific monomer compositions and additive packages that create distinct functional characteristics: high initial adhesion for sealing, controlled blocking resistance for release coating compatibility, and sustained reclosure forces. Each functional requirement is addressed by specific compositional elements within the overall formulation.
4Ease of operation
If organic solvents are used in adhesive compositions, then application ease is improved, but health hazards and environmental impact increase
Solution Approach 1:
The patent replaces organic solvent-based adhesive compositions with water-based polymer dispersions. This substitution eliminates the health hazards and environmental concerns associated with organic solvents while maintaining effective application properties through proper dispersion formulation and coating process optimization.
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
The solution provides a cold-sealable and resealable packaging with high seal seam strength, effective blocking resistance, and sustained reclosure forces, while being free from allergenic potential and organic solvents, suitable for common application techniques and film substrates.
Implementation Method 1
the emulsion polymer being produced by emulsion polymerization of free-radically polymerizable monomers in the presence of at least one protective colloid
Implementation Method 2
Cold sealable means that when two surfaces coated and dried with a composition according to the invention come into contact at temperatures of less than 40 °C, in particular less than 30 °C or less than 25 °C, in particular at room temperature (20 °C) while applying pressure are brought together, stick together
Implementation Method 3
They differ from pressure-sensitive adhesives in that they have little or no stickiness at room temperature. They differ from heat-sealable compositions in that they can be bonded together under pressure without heat activation. Cold-sealable compositions are known, for example for sealing bag-shaped packaging
Data Source
AI summary
The invention relates to a recloseable packaging having a cold sealed adhesive layer that can be reclosed after the packaging is opened, wherein the adhesive layer comprises a polymer in emulsion made of at least 60 wt% of main monomers selected from the group made up of C1 to C20-alkyl(meth)acrylates, vinyl esters of up to 20 C atoms comprising carbolic acids, vinyl aromates having up to 20 C atoms, ethylene unsaturated nitriles, vinyl halogenides, vinyl ethers of alcohols comprising 1 to 10 C atoms, aliphatic hydrocarbons having 2 to 8 C atoms and one or two double bonds, and mixtures of said monomers, wherein the polymer in emulsion can be produced by means of emulsion polymerization of radically polymerizable monomers in the presence of at least one protective colloid. The invention further relates to aqueous polymer dispersions suitable for producing the packaging according to the invention, and to polymer films coated with the polymer dispersion.