Prepreg Adhesion via Styrene-Acrylate Copolymer

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Solution Overview

Problem

Existing decorative pre-impregnation materials containing formaldehyde-free resins lack sufficient adhesion, splitting strength, and printability, particularly when applied to wood-based panels, and often result in brittle products with poor tear resistance.

Innovation Solution

A pre-impregnation solution using a styrene-alkyl acrylate-hydroxyethyl (meth)acrylate copolymer and a water-soluble polymer, such as starch dextrin, with a specific molecular weight distribution, applied at a concentration of 10-35% by weight on decorative raw paper, enhancing adhesion, splitting strength, and printability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If formaldehyde-free resins are used for impregnation, then health safety is improved, but adhesion and splitting strength deteriorate

Engineering Contradiction:
Improveformaldehyde contentVSAvoidadhesion and splitting strength
Core Design Contradiction:
Object-affected harmful factorsVSStrength

Solution Approach 1:

The patent uses a composite binder system combining polyvinyl acetate (PVAC) with at least one additional polymer component (such as polyacrylonitrile, polyacrylic acid, or carboxymethyl cellulose). This composite approach allows the PVAC to provide base adhesion while the additional polymer enhances splitting strength and bonding properties, achieving both health safety (formaldehyde-free) and mechanical performance

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent optimizes the molecular weight distribution of the polymers used, specifically requiring the additional polymer to have a weight average molecular weight of 10,000-1,000,000 and number average molecular weight of 1,000-100,000. This parameter control ensures optimal balance between adhesion and splitting strength while maintaining formaldehyde-free composition

Inventive Principle:
Principle #35Parameter changes

2Shape

If decorative paper is smoothed with soft calenders, then surface topography is improved for printing, but resin absorption capacity deteriorates

Engineering Contradiction:
Improvesurface smoothnessVSAvoidresin absorption capacity
Core Design Contradiction:
ShapeVSQuantity of substance

Solution Approach 1:

The patent controls the calendering parameters to achieve surface smoothness without excessive compression. By optimizing the calendering pressure and temperature parameters, the paper surface becomes smooth enough for gravure printing while maintaining sufficient porosity and resin absorption capacity for proper impregnation

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If printing ink penetrates deeply into paper structure, then color intensity decreases, but printability is improved

Engineering Contradiction:
ImproveprintabilityVSAvoidcolor intensity
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The patent optimizes the paper's physical parameters including basis weight (15-300 g/m²) and surface properties to control ink penetration depth. The controlled porosity and surface characteristics allow ink to penetrate sufficiently for good printability while maintaining color intensity by preventing excessive absorption

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2537682B1Prepreg
Publication Date: 2016.01.06 SCHOELLER TECHNOCELL GMBH & CO KG

AI summary

A pre-impregnated material for further processing as decorative paper is obtained by impregnating a decorative base paper with a resin impregnation solution containing at least one styrene-alkyl acrylate-hydroxyethyl methacrylate copolymer and at least one water-soluble polymer, where alkyl means methyl, ethyl, propyl or butyl, and the pre-impregnated material is characterized by improved cleavage resistance, adhesion and flatness.