A continuous production method of a full-breathable slow-rebound sponge

Abstract

The present application relates to polyurethane sponge manufacturing technology, disclose a kind of continuous production method of full air-permeable slow rebound sponge, the method includes: raw material is transported to forming machine by constant temperature conveying system;Three-stage gradient foaming process is implemented: negative pressure 0.5kPa is raised to 50 DEG C in rising period, pressure is increased to normal pressure and is reduced to 35 DEG C in gel period, and pulse pressure relief in open hole period;Foaming embryo passes through zoned temperature drying equipment in turn;After drying, sponge is cut by 20kHz high-frequency vibration knife and 10kPa negative pressure adsorption;Finished product is collected by air suspension stacking system of 0.5-1m / s vertical airflow, and the present application breaks through and realizes the synergistic optimization of air permeability ≥5m³ / m² / min and ball rebound rate ≤35%, simultaneously, the ripening period is shortened from 72 hours to ≤4 hours drying+16 hours adjustment, solve the performance imbalance and low efficiency problem of traditional process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polyurethane sponge manufacturing, and particularly relates to a continuous production method of full-air-permeable slow-rebound sponge. BACKGROUND

[0002] In the field of polyurethane slow-rebound sponge manufacturing, the traditional production process has significant defects, which restricts the synchronous improvement of product performance and production efficiency. At present, the mainstream adopts an intermittent foaming mode, raw materials are mixed and then injected into a mold for free foaming, and the reaction process is monitored by manual control. This mode leads to poor uniformity of the cell structure, and the air permeability and rebound rate of the same batch of sponge fluctuate by more than 20%, which is difficult to meet the strict requirements of high-end application scenarios on performance consistency.

[0003] The curing link of slow-rebound sponge is particularly time-consuming. The industry standard operation process requires that the sponge after foaming must be placed in an environment of 23±2 DEG C and 50%±5% relative humidity for at least 72 hours to ensure stable physical properties. Although studies have shown that the curing time can be shortened to 48 hours, the product performance stability is sacrificed, and the balance between efficiency and quality cannot be achieved.

[0004] In terms of achieving the coordination of high air permeability and slow rebound characteristics, the existing technology faces a fundamental contradiction. In order to improve the air permeability, the amount of pore-forming agent needs to be increased or negative pressure needs to be applied to promote the rupture of the cells, but this will weaken the strength of the polymer network, resulting in an increase in the rebound rate; on the contrary, increasing the slow rebound performance needs to increase the cross-linking density, which is easy to form a closed cell structure, making the air permeability decrease to below 3 m³ / m² / min. Existing solutions such as high-temperature rapid curing can shorten the cycle, but will cause surface hardening, and the air permeability loss is more than 30%.

[0005] In addition, subsequent processing procedures further damage the product performance. Traditional cutting uses a mechanical press plate to fix the sponge, and the compression force applied causes the cell structure to collapse permanently, and the cell damage rate is more than 15%; the extrusion deformation in the manual stacking and handling process further reduces the viscoelastic recovery characteristics of the slow-rebound sponge by more than 40%.

[0006] Therefore, it is urgent to develop a full-automatic continuous production method to break through the performance balance bottleneck of air permeability and rebound rate, to simultaneously solve the problems of low curing efficiency and processing damage, and to realize the large-scale stable manufacturing of high-performance slow-rebound sponge. SUMMARY

[0007] In order to overcome the above-mentioned defects of the prior art, the embodiments of the present application provide a continuous production method of full-air-permeable slow-rebound sponge.

[0008] To achieve the above-mentioned purpose, the present application has the following innovative points: comprising the following steps:

[0009] (a) The raw materials are conveyed to the sponge molding machine via a constant temperature conveying system;

[0010] (b) Implement a three-stage pressure-temperature gradient foaming process in the molding machine;

[0011] (c) The foamed preform is fed into a zoned variable temperature drying equipment for maturation;

[0012] (d) The cured sponge is cut by a high-frequency vibrating knife;

[0013] (e) The cut finished products are collected through an air suspension stacking system.

[0014] Furthermore, the constant temperature conveying system described in step (a) maintains the raw material temperature at 25±0.5℃.

[0015] Furthermore, temperature control is achieved by dynamically adjusting the electric heat tracing device using a PID control algorithm.

[0016] Furthermore, step (b) of the three-stage pressure-temperature gradient foaming process includes:

[0017] During the rising phase, the temperature is increased to 50℃ under a negative pressure of 0.5 kPa.

[0018] gelation period: pressurize to atmospheric pressure at a rate of 2 kPa per second and maintain constant pressure, while cooling to 35°C;

[0019] Opening period: Apply periodic pressure relief operations and maintain the temperature at 35°C.

[0020] Furthermore, the pressure change direction of the aforementioned periodic pressure relief operation is from 0 kPa to -1 kPa, and the frequency is 1 Hz.

[0021] Furthermore, step (c) involves dividing the zoned temperature-controlled drying equipment into three independent control zones:

[0022] Zone 1, temperature 60℃ and relative humidity 20%;

[0023] Zone 2, temperature 45℃ and relative humidity 40%;

[0024] Zone 3, temperature 25℃ and relative humidity 55%.

[0025] Furthermore, the dried sponge is conditioned at 23±2℃ and 50%±5%RH for ≥16 hours.

[0026] Furthermore, in step (d), the cutting blade vibrates at a frequency of 20 kHz.

[0027] Furthermore, in step (d), a negative pressure adsorption force of 10 kPa is applied to the cutting table.

[0028] Furthermore, in step (e), the airflow velocity of the air suspension stacking system is 0.5 m / s to 1 m / s, and the airflow direction is perpendicular to the falling trajectory of the sponge.

[0029] The beneficial effects of this invention are:

[0030] 1. Achieving synergistic optimization of high air permeability and low resilience: Through the synergistic effect of a three-stage gradient foaming process (negative pressure expansion during the rising phase, pressurization and locking during the gelation phase, and pulse pressure relief during the opening phase) and zoned variable temperature drying, the cell opening rate and polymer network crosslinking density are precisely controlled at the molecular level.

[0031] The air permeability is increased to ≥5m³ / m² / min (ASTM D3574 Test G standard, 125Pa pressure difference), which is more than 67% higher than the traditional process (≤3m³ / m² / min); the ball rebound rate is reduced to ≤35% (GB / T6670 standard, 16.5g steel ball at a height of 500mm), which is more than 12.5% ​​lower than the traditional process (≥40%). At the same time, it breaks through the technical contradiction of slow rebound sponge that "open pores increase rebound, and closed pores decrease air permeability" (see Example 1: air permeability 6.3m³ / m² / min + rebound rate 31%).

[0032] 2. Revolutionary improvement in curing efficiency: Innovatively adopting humidity-guided zoned variable temperature drying (60℃ / RH20%→45℃ / RH40%→25℃ / RH55%), combined with standard environmental conditioning after drying (23±2℃ / 50%±5%RH, ≥16 hours):

[0033] The total curing time is shortened to ≤4 hours (drying) + 16 hours (adjustment), which is 260% more efficient than the industry-required 72-hour curing cycle. Through dynamic moisture content feedback control (zone 1 reduces surface moisture, zone 2 reduces core moisture, and zone 3 balances), the performance is ensured to fully meet the standards (comparative example 1 shows that the rebound rate of traditional drying exceeds the standard by 45%), solving the industry problem of "performance degradation caused by accelerated curing" (see example 1: rebound rate of 31% after 3 hours of drying + 16.5 hours of adjustment). Attached Figure Description

[0034] Figure 1 This is a process flow diagram of the present invention.

[0035] Figure 2 This is a pressure-temperature curve diagram of the three-stage foaming process of the present invention. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Example 1

[0038] Example 1: Production of automotive seat foam.

[0039] Raw material formula:

[0040] Polyether polyol (Mn=3000, OH value 56mgKOH / g): 60 parts

[0041] Modified MDI (NCO%=30.5): 40 parts

[0042] Pore ​​opener (silicone oil type L-580): 1.2 parts

[0043] Slow rebound additive (damping polymer microspheres VX-200): 2.5 parts

[0044] Production process:

[0045] 1. Constant temperature conveying:

[0046] The raw materials are transported via electrically heated pipelines, with the temperature controlled by PID at 25.0±0.3℃ (actually measured at 25.1℃) and the flow rate at 0.5m³ / h.

[0047] 1. Three-stage gradient foaming:

[0048] Stage Parameter Device operation Rise Vacuum -0.5 kPa, temperature rise to 50.2°C Vacuum pump + infrared heating Gelation Pressure increase rate +2.1 kPa / s, temperature drop to 34.8°C Nitrogen pressure valve + water-cooled plate Opening Pressure relief amplitude 0→-1.0 kPa, frequency 1.0 Hz Electromagnetic pulse valve periodic start-stop

[0049] 2. Zoned temperature-controlled drying:

[0050] Zone 1: 60.5℃ / RH19% (40 min residence time, surface moisture content 12%→8%).

[0051] Zone 2: 44.8℃ / RH42% (stay for 100 min, core moisture content 15%→5%).

[0052] Zone 3: 25.0℃ / RH54% (stay for 60 min, equilibrium moisture content 3.2%).

[0053] After drying, adjust the temperature to 23.5℃ / 50%RH and let it stand for 16.5 hours.

[0054] 3. High-frequency vibration cutting:

[0055] The ultrasonic scalpel has a frequency of 20.0 kHz (amplitude 50 μm), a cutting table negative pressure of -10.2 kPa, and a cutting size of 50 × 50 cm.

[0056] 4. Air suspension stacking:

[0057] Airflow velocity 0.82m / s, vertically upward spray, stack height 1.2m (10 layers).

[0058] Performance testing (according to WI-QC-S008 / S001 standards):

[0059] Air permeability: 6.3 m³ / m² / min (ASTM D3574G, 125 Pa).

[0060] Ball rebound rate: 31% (GB / T6670, 16.5g steel ball 500mm).

[0061] Example 2: Medical mattress foam (adjusting parameters):

[0062] Raw material adjustment: Increase the amount of pore-opening agent to 1.8 parts and reduce the amount of slow rebound agent to 1.8 parts.

[0063] Process change points:

[0064] The pressure relief frequency during the orifice opening period is 1.2 Hz;

[0065] The airflow velocity in the air flotation stack is 0.55 m / s.

[0066] Test results: air permeability 7.1 m³ / m² / min, resilience 34%.

[0067] Example 3: Insole Sponge (Extreme Parameter Verification):

[0068] Process boundary testing:

[0069] Constant temperature conveying temperature: 24.5℃;

[0070] Pressurization rate during gelation: +1.9 kPa / s;

[0071] Cutting negative pressure: -9.8 kPa;

[0072] Test results: air permeability: 5.2 m³ / m² / min, rebound rate: 35% (still meets the standard).

[0073] Comparative Example 1: Traditional process (highlighting the effect of the invention)

[0074] Step Operation Defect Raw material transfer No temperature control, ambient temperature fluctuation (22°C-28°C) Foaming uneven Foaming process Normal pressure foaming, natural curing Insufficient opening rate Curing Constant temperature 50°C, drying for 24 hours Surface hardening Cutting Ordinary blade, mechanical pressing plate Cell pressure loss rate 18% Stacking Manual stacking Permanent deformation

[0075] Test results: air permeability 2.8 m³ / m² / min, resilience 45%.

[0076] Finally, the following points should be noted: First, in the description of this application, it should be noted that, unless otherwise specified and limited, the terms "installation", "connection", and "linkage" should be interpreted broadly, and can be mechanical or electrical connections, or internal connections between two components, or direct connections. "Up", "down", "left", "right", etc. are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may change.

[0077] Secondly: The accompanying drawings of the embodiments disclosed in this invention only involve the structures involved in the embodiments disclosed in this invention. Other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of this invention can be combined with each other.

[0078] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A continuous production method for fully breathable slow-rebound sponge, characterized in that, Includes the following steps: (a) The raw materials are conveyed to the sponge molding machine via a constant temperature conveying system; (b) Implement a three-stage pressure-temperature gradient foaming process in the molding machine; (c) The foamed preform is fed into a zoned variable temperature drying equipment for maturation; (d) The cured sponge is cut by a high-frequency vibrating knife; (e) The cut finished products are collected through an air suspension stacking system; The three-stage pressure-temperature gradient foaming process described in step (b) includes: During the rising phase, the temperature is increased to 50℃ under a negative pressure of 0.5 kPa. gelation period: pressurize to atmospheric pressure at a rate of 2 kPa per second and maintain constant pressure, while cooling to 35°C; Opening period: Apply periodic pressure relief operations and maintain the temperature at 35℃; The pressure change direction of the periodic pressure relief operation is from 0 kPa to -1 kPa, and the frequency is 1 Hz; The zoned variable temperature drying equipment described in step (c) is divided into three independent control zones: Zone 1, temperature 60℃ and relative humidity 20%; Zone 2, temperature 45℃ and relative humidity 40%; Zone 3, temperature 25℃ and relative humidity 55%.

2. The continuous production method of a fully breathable slow-rebound sponge according to claim 1, characterized in that, The constant temperature conveying system described in step (a) maintains the raw material temperature at 25±0.5℃.

3. The continuous production method of a fully breathable slow-rebound sponge according to claim 2, characterized in that, Temperature control is achieved by dynamically adjusting the electric heat tracing device using a PID control algorithm.

4. The continuous production method of a fully breathable slow-rebound sponge according to claim 1, characterized in that, After drying, the sponge is conditioned at 23±2℃ and 50%±5%RH for ≥16 hours.

5. A continuous production method for a fully breathable slow-rebound sponge according to claim 1, characterized in that, In step (d), the cutting blade vibrates at a frequency of 20 kHz.

6. The continuous production method of a fully breathable slow-rebound sponge according to claim 1, characterized in that, In step (d), a negative pressure adsorption force of 10 kPa is applied to the cutting table.

7. A continuous production method for a fully breathable slow-rebound sponge according to claim 1, characterized in that, In step (e), the airflow velocity of the air suspension stacking system is 0.5 m / s to 1 m / s, and the airflow direction is perpendicular to the falling trajectory of the sponge.

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