Analysis of the Flexibility and Plasticity of Acrylic solid Surfaces
The flexibility and plasticity of the solid surface of acrylic acid are jointly influenced by the molecular structure of the resin, the curing mechanism and external conditions. The following analysis is conducted from three dimensions: material properties, influencing factors and application scenarios:
First, the sources and manifestations of flexibility
Molecular chain flexibility
アクリル樹脂の柔軟性は、主にメインチェーンのエステル基（-COO-）とアルキル基（-R）の構造に依存します。たとえば、長鎖アルキル基（C8-C12など）の導入により、分子鎖の遊離体積が増加し、ガラス遷移温度（TG）を下げ、それにより柔軟性が向上します。柔軟なモノマー（アクリル酸ブチルなど）がメインチェーンに導入されると、コーティングは割れずに室温で180°曲げに耐えることができます。ただし、ハードモノマー（メチルメタクリレートなど）の割合が高すぎると、コーティングの脆性が大幅に増加します。
架橋密度の影響
The dosage of crosslinking agents (such as diisocyanates and epoxy resins) directly affects flexibility. For example, when the crosslinking density is too high, the coating may break due to stress concentration during the bending test. Moderate crosslinking (such as a crosslinking degree of 30-50%) can balance hardness and flexibility, enabling the coating to maintain a certain hardness while having impact resistance.
Temperature dependence
The flexibility of the acrylic coating increases with the rise in temperature. For example, at -20℃, the coating may exhibit brittle fracture; At 60℃, its elongation at break can increase by 2 to 3 times. This characteristic requires that when used in low-temperature environments, the formula needs to be optimized (such as adding plasticizers) to maintain flexibility.
Second, the realization mechanism of plasticity
Thermoplastic processing
Incompletely cured acrylic resin can achieve plasticity through thermoplastic processing. For instance, at 120-150℃, the resin can be calendered, blow-molded or injection-molded, and retains its shape after cooling. This characteristic is applicable to the manufacturing of complex-shaped products (such as irregular-shaped decorative parts), but the processing temperature needs to be controlled to avoid thermal degradation.
Solvent-assisted shaping
The viscosity of the resin can be reduced and its plasticity enhanced by adding volatile solvents (such as ethyl acetate). For instance, when the solvent content is 20-30%, the resin can be coated or sprayed into a thin layer, and a dense coating is formed after the solvent evaporates. This method is applicable to large-scale construction (such as the exterior walls of buildings), but it is necessary to pay attention to the influence of the solvent evaporation rate on the flatness of the coating.
Light curing and reversible crosslinking
Some acrylic resins can be photocured by photoinitiators, while reversible cross-linking bonds (such as disulfide bonds and hydrogen bonds) are introduced to enhance plasticity. For example, under ultraviolet light irradiation, the resin can be cured and formed within seconds. Under the influence of heating or specific solvents, the crosslinking bonds can break, achieving secondary shaping. This feature is applicable to scenarios that require repetitive processing (such as 3D printing).
Third, the key factors influencing flexibility and plasticity
Composition of resin monomers
ソフトモノマー（アクリール酸エチル酸エチル酸エチル酸エチル酸エチル酸エチル酸エチル酸エチル酸塩など）とハードモノマー（メチルメタクリレートやスチレンなど）の比は、柔軟性に直接影響します。たとえば、ソフトモノマーの割合が60％を超えると、コーティングの柔軟性が大幅に改善されますが、硬度は不十分である可能性があります。ハードモノマーの割合が高すぎると、コーティングは割れやすくなります。
可塑剤と修飾子
可塑剤（フタル酸ジオクチルなど）は、分子間力を減らし、柔軟性を高めることができます。たとえば、5〜10％の可塑剤を追加すると、コーティングの破損時の伸長が50％以上増加する可能性がありますが、耐熱性と耐薬品性を低下させる可能性があります。さらに、ナノフィラー（シリカやカーボンナノチューブなど）の導入は、物理的な架橋により柔軟性と強度を高めることができます。
硬化条件
The curing temperature and time have a significant influence on flexibility and plasticity. For instance, low-temperature curing (such as 40℃) may lead to incomplete crosslinking, resulting in a coating with good flexibility but insufficient hardness. High-temperature curing (such as 120℃) can accelerate the crosslinking reaction, increase hardness but may reduce flexibility. In addition, the flexibility of the UV-curable coating can be controlled by adjusting the concentration of the photoinitiator and the intensity of the light.
Fourth, the requirements for flexibility and plasticity in application scenarios
Architectural coating
Exterior wall coatings need to have a certain degree of flexibility to resist thermal expansion and contraction caused by temperature changes. For instance, in areas with a large temperature difference between day and night, the coating needs to have an elongation at break of 10-15% to prevent cracking. In addition, plasticity requires that the coating can evenly cover the surface of complex substrates (such as brick walls and stone).
Automobile coating
Components such as car bumpers need to be both flexible and malleable. For example, the coating needs to maintain flexibility within the range of -40℃ to 80℃, and at the same time be able to withstand minor impacts without peeling off. In addition, plasticity requires that the coating can adapt to the injection molding process and form a smooth surface.
3D printing materials
Uv-curable acrylic resin needs to be malleable to achieve printing of complex structures. For instance, the resin needs to cure rapidly under ultraviolet light while maintaining a certain degree of flexibility to prevent breakage during the printing process. In addition, the printed products need to have sufficient strength to withstand the usage load.
Fifth, strategies for enhancing flexibility and plasticity
Molecular design
Flexible segments are introduced through copolymerization or grafting modification. For instance, introducing polyether segments (such as polyethylene glycol methacrylate) into acrylic resin can significantly enhance flexibility while maintaining water resistance.
Composite modification
Blend acrylic resin with elastomers (such as nitrile rubber, polyurethane). For instance, adding 10-20% elastomer can increase the impact strength of the coating by 3-5 times while maintaining transparency.
Post-treatment process
熱処理または溶媒アニーリングを通じてコーティング構造を最適化します。たとえば、100℃で2時間の熱処理では、コーティングの内部応力が放出され、柔軟性が向上します。溶媒アニーリングは、分子鎖の再配置を促進し、可塑性を高めることができます。
