Hot-Melt Adhesive Agent for Polyolefin Substrates
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Solution Overview
Problem
Existing hot-melt adhesive agents for disposable products like paper diapers face challenges in achieving low-temperature applicability, adhesiveness to polyolefin substrates, and creep resistance, particularly when incorporating rubber threads, leading to issues with film heat resistance and fitting properties.
Innovation Solution
A hot-melt adhesive agent comprising a thermoplastic block copolymer with a radial type styrene block copolymer and a styrene block copolymer, along with a tackifier resin, which provides low melt viscosity, excellent adhesiveness, and creep resistance, enabling application at low temperatures and maintaining elasticity of rubber threads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the amount of base polymer is decreased to increase the amount of plasticizer, then the viscosity of the hot-melt adhesive agent is lowered, but the balance between adhesiveness to polyethylene film and retention force is deteriorated and the softening point is excessively lowered
Solution Approach 1:
The patent changes the chemical composition parameters by introducing a specific block copolymer component with controlled styrene content (20-40%) and diblock content (30-70%), which modifies the adhesive's molecular structure to achieve optimal balance between viscosity, adhesiveness, and retention force without excessive softening
Solution Approach 2:
The patent creates a composite adhesive system combining multiple components: base polymer, plasticizer, and a specific block copolymer component. This composite formulation allows the adhesive to simultaneously achieve low viscosity for workability, sufficient adhesiveness to polyethylene film, and adequate retention force through the synergistic interaction of different materials
2Ease of manufacture
If a high-temperature (not lower than 150° C.) hot-melt adhesive agent is used, then the adhesive agent can be applied effectively, but the polyethylene film melts or forms wrinkles due to poor heat resistance
Solution Approach 1:
The patent modifies the thermal parameters of the adhesive system by incorporating a block copolymer component that lowers the softening point and enables effective application at lower temperatures (below 150°C), thereby preventing polyethylene film melting and wrinkle formation while maintaining adequate adhesive performance
3Reliability
If the hot-melt adhesive agent has insufficient creep resistance, then the rubber thread cannot be held at the bonded position, but the paper diaper unit is not folded and thus expansion and shrinkage forces are not applied to the paper diaper unit
Solution Approach 1:
The patent changes the mechanical properties of the adhesive by incorporating a block copolymer component with specific molecular structure that provides adequate creep resistance to hold the rubber thread at the bonded position while allowing the paper diaper unit to fold properly when the rubber thread shrinks, enabling the expansion and shrinkage forces to be applied to the paper diaper unit
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 adhesive agent effectively applies at low temperatures, maintains adhesiveness to polyolefin substrates, and ensures the rubber thread's elasticity is applied to the paper diaper, enhancing its fitting properties and durability.
Implementation Method 1
the hot-melt adhesive agent is melted by heating so as to obtain an appropriate viscosity
Implementation Method 2
a paper diaper is produced by bonding a polyethylene film with other members using a hot-melt adhesive agent
Implementation Method 3
the drawn rubber thread is bonded to a paper diaper unit. A hot-melt adhesive agent is usually used as an adhesive agent. The paper diaper unit commonly has no elasticity. Therefore, the paper diaper including the rubber thread bonded thereto is folded by a shrinkage force of the rubber thread when the rubber thread bonded to the paper diaper shrinks
Data Source
AI summary
The present invention provides a hot-melt adhesive agent which is capable of applying at low temperature, and has an excellent adhesiveness to a polyolefin substrate, and a disposable product obtained by employing the hot-melt adhesive agent. A hot-melt adhesive agent comprising a thermoplastic block copolymer (A) which is a copolymer of vinyl class aromatic hydrocarbons and conjugated diene compounds, whereinthe thermoplastic block copolymer (A) comprises the following component (A1) and component (A2):(A1) a radial type styrene block copolymer having a styrene content of 35 to 45% by weight and a diblock content of 50 to 90% by weight, and having a viscosity at 25° C. as a 25% (by weight) toluene solution of not more than 250 mPa·s; and(A2) a styrene block copolymer having a styrene content of less than 30% by weight, and having a viscosity at 25° C. as a 25% (by weight) toluene solution of more than 250 mPa·s.