Process and plant for continuous manufacture of resting articles of latex foam

Process for continuous manufacture of a block of latex foam of un-limited length to be partitioned in a plurality of mattresses by transversal cuts to said un-limited length, comprising the steps of:

• preparing a latex formed by various particles and by a surfactant to originate a barrier contrasting the approach among said latex particles,
• forming a first latex and components base mixture,
• introducing into said first base mixture a foaming agent,
• then foaming the first base mixture,
• then introducing into said foamed first base mixture a gelation agent destined to break said barrier,
• advancing along a predetermined direction a preheated metal laying surface provided with protuberances to mould recesses between a first and a second station and for gelating and vulcanising in a diffused way, the length measured between the two stations being between 25 m to 50 m,
• laying at that first station said first foamed base mixture containing the gelating agent over said preheated laying surface with protuberances in continuous advancement and forming a first base layer of latex foam of un-limited length with recesses moulded into the first base layer, the moulding of recesses into the first base layer comprising the protuberances impressing the recesses into the deposited first foamed base mixture during said latex foam base mixture laying;
• shaping said first base layer with recesses to a height between 10 cm and 25 cm;
• preparing a second latex foam mixture comprising said surfactant and said gelation agent;
• the second latex foam mixture and the foamed first base mixture having different densities, wherein the ratio between the second latex foam mixture and the foamed first base mixture density is between >1 and 10, characterized in foaming the second mixture with an air amount different from the first base mixture so the resulting layers of the block of latex foam differ in density;
• laying after the first layer shaping step said second mixture over at least a partial cross extension of said first base layer and forming a second latex foam upper layer so the second layer contacts the first layer;
• shaping said second layer to a predetermined height between 5 cm and 20 cm, wherein the ratio between said second layer thickness and said base layer thickness is between 0.5 and 1;
• moving after said shaping of the second layer said first base layer and said second upper layer both still dimensionally unstable a distance “T” comprised between 1 m and 2 m, so co-penetration of the two layers consists of a gravity penetration of micro-porous structure of both layers;
• gelating said first layer and gelating said second layer;
• said gelating comprising thermal conduction of heat from the pre-heated said metal laying surface with protuberances towards the first layer and second layer, wherein gelating said first layer comprises gelating a portion of said first layer during the impressing of recesses step;
• vulcanising both said gelated layers simultaneously;
• advancing towards the second station said latex foam block formed by at most said two layers.