Continuous production method of full-breathable slow-rebound sponge

Abstract

The invention relates to a polyurethane sponge manufacturing technology, and discloses a continuous production method of full-breathable slow-rebound sponge, which comprises the following steps: conveying raw materials to a forming machine through a constant-temperature conveying system; the negative pressure is 0.5 kPa in the rising period, the temperature is increased to 50 DEG C, the pressure is increased to normal pressure in the gelation period, the temperature is decreased to 35 DEG C, and pulse pressure relief is conducted in the trepanning period; foaming blanks sequentially pass through the partitioned variable-temperature drying equipment; the dried sponge is cut through a 20 kHz high-frequency vibration cutter and 10 kPa negative pressure adsorption; the finished product is collected by a 0.5-1m / s vertical air flow air suspension stacking system, the collaborative optimization that the air permeability is larger than or equal to 5m / m / min and the falling ball rebound rate is smaller than or equal to 35% is achieved in a breakthrough mode, meanwhile, the curing period is shortened from 72 hours to be smaller than or equal to 4 hours and smaller than or equal to 16 hours for adjustment, and the problems of performance imbalance and low efficiency of a traditional technology are solved.

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 material is transported to the sponge forming machine by a constant temperature conveying system;

[0010] (b) The three-stage pressure-temperature gradient foaming process is implemented in the forming machine;

[0011] (c) The foamed embryo is sent to the partitioned temperature drying equipment for curing;

[0012] (d) After curing, the sponge is cut by a high-frequency vibrating knife;

[0013] (e) The cut products are collected by the gas suspension stacking system.

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

[0015] Further, the temperature control is achieved by dynamically adjusting the electric heat tracing device through the PID control algorithm.

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

[0017] Rising period, temperature rises to 50℃ under -0.5kPa negative pressure;

[0018] Gel period: increase the pressure to normal pressure at a rate of 2kPa / s and maintain constant pressure, while the temperature decreases to 35℃;

[0019] Open hole period: periodic pressure relief operation is applied, and the temperature is maintained at 35℃.

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

[0021] Further, the partitioned temperature drying equipment in step (c) is divided into three independent control zones:

[0022] First zone, temperature 60℃ and relative humidity 20%;

[0023] Second zone, temperature 45℃ and relative humidity 40%;

[0024] Third zone, temperature 25℃ and relative humidity 55%.

[0025] Further, the sponge is adjusted in an environment of 23±2℃, 50%±5%RH for ≥16 hours after drying.

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

[0027] Further, the cutting table in step (d) applies a negative pressure adsorption force of 10kPa.

[0028] Further, the air flow speed of the air suspension stacking system in step (e) is 0.5 m / s to 1 m / s, and the air flow direction is perpendicular to the falling track of the sponge.

[0029] The beneficial effects of the present application are:

[0030] 1. Synergistic optimization of high air permeability and low resilience: Through the synergistic effect of three-stage gradient foaming process (upward period negative pressure hole expansion, gel period pressure locking resilience, and open hole period pulse pressure relief) and zoned temperature drying, the pore opening rate and polymer network crosslinking density are accurately controlled at the molecular level:

[0031] The air permeability is increased to ≥5 m³ / m² / min (ASTM D3574 Test G standard, 125 Pa pressure difference), which is increased by more than 67% compared with the traditional process (≤3 m³ / m² / min); the falling ball resilience is reduced to ≤35% (GB / T 6670 standard, 16.5 g steel ball 500 mm height), which is reduced by more than 12.5% compared with the traditional process (≥40%), and the technical contradiction of slow rebound sponge "open hole then rebound increases, closed pore then air permeability decreases" is broken through (see Example 1: air permeability 6.3 m³ / m² / min + resilience 31%).

[0032] 2. Maturity efficiency is improved: innovative use of humidity-guided zoned temperature drying (60℃ / RH20%→45℃ / RH40%→25℃ / RH55%), combined with standard environment adjustment 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 period; through dynamic moisture content feedback control (zone 1 reduces surface moisture, zone 2 reduces core moisture, and zone 3 balances), the performance fully meets the standard (Example 1: 3 hours of drying + 16.5 hours of adjustment, resilience 31%), and solves the industry problem of "accelerating curing leading to performance degradation" (see Example 1: 3 hours of drying + 16.5 hours of adjustment, resilience 31%). BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The process flow chart of the present application.

[0035] Figure 2 The three-stage foaming pressure-temperature curve of the present application. DETAILED DESCRIPTION

[0036] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0037] Example 1

[0038] Example 1: Sponge production for car seat.

[0039] Raw material formula:

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

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

[0042] Cell opener (silicone oil L-580): 1.2 parts

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

[0044] Production process:

[0045] 1. Constant temperature conveying:

[0046] The raw materials are conveyed through an electric heat tracing pipeline, and the temperature is controlled by PID to 25.0±0.3℃ (actually 25.1℃), and the flow rate is 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. Partitioned variable temperature drying:

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

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

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

[0053] After drying, adjust: 23.5℃ / 50%RH environment for 16.5 hours.

[0054] 3. High-frequency vibration cutting:

[0055] Ultrasonic knife frequency 20.0 kHz (amplitude 50 pm), cutting table negative pressure -10.2 kPa, cutting size 50 x 50 cm.

[0056] 4. Air suspension stacking:

[0057] Air flow velocity 0.82 m / s, vertically upward injection, stacking height 1.2 m (10 layers).

[0058] Performance test (according to WI-QC-S008 / S001 standard):

[0059] Air permeability: 6.3 m³ / m² / min (ASTM D3574 G, 125 Pa).

[0060] Ball drop rebound rate: 31% (GB / T 6670, 16.5 g steel ball 500 mm).

[0061] Example 2: Medical mattress sponge (adjust parameters):

[0062] Raw material adjustment: increase the pore opening agent to 1.8 parts, and reduce the slow rebounding aid to 1.8 parts.

[0063] Process change point:

[0064] Pressure relief frequency 1.2 Hz during the pore opening period;

[0065] Air flow velocity 0.55 m / s for air suspension stacking.

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

[0067] Example 3: Insole sponge (extreme parameter verification):

[0068] Process boundary test:

[0069] Constant temperature conveying temperature: 24.5°C;

[0070] Gel period pressure increasing rate: +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 up to 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, rebound rate 45%.

[0076] Finally should be explained a few points are: first, in the description of the present application, it should be pointed out that, unless otherwise specified and limited, the term "installation", "connected", "connection" should be broad, can be mechanical or electrical connection, but also can be two elements inside the communication, can be directly connected, "up", "down", "left", "right" and so on, only for indicating the relative position relationship, when the absolute position of the described object changes, the relative position relationship may change;

[0077] Second: the present application discloses the drawings in the embodiment, only involves the structure related to the present application, other structures can refer to the usual design, in the case of no conflict, the same embodiment and different embodiments of the present application can be combined with each other;

[0078] Finally: the above only for the preferred embodiment of the present application, and not for limiting the present application, any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application, should be included in the protection scope of the present application.

Claims

1. A continuous production method of a full air permeable slow rebound sponge, characterized by, The method comprises the following steps: (a) raw materials are transported to a sponge forming machine by a constant temperature conveying system; (b) a three-stage pressure-temperature gradient foaming process is implemented in the forming machine; (c) the foamed embryo is sent to a partitioned variable temperature drying device for curing; (d) after curing, the sponge is cut by a high-frequency vibrating knife; (e) the cut products are collected by an air suspension stacking system.

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

3. A continuous process for producing a full air permeable slow rebound sponge according to claim 2, characterized in that, The temperature control is achieved by dynamically adjusting the electric heat tracing device through a PID control algorithm.

4. The continuous production method of a full-breathable slow-rebound sponge according to claim 1, characterized in that, The three-stage pressure-temperature gradient foaming process in step (b) comprises: rising period, temperature is raised to 50℃ under a negative pressure of 0.5kPa; gelation period, the pressure is increased to normal pressure at a rate of 2kPa / s and the temperature is lowered to 35℃ while maintaining constant pressure; open cell period, periodic pressure relief operation is applied, and the temperature is maintained at 35℃.

5. A continuous process for producing a full air permeable slow rebound sponge according to claim 4, characterized in that, The pressure change direction of the periodic pressure relief operation is from 0kPa to negative 1kPa, and the frequency is 1Hz.

6. The continuous production method of a full-breathable slow-rebound sponge according to claim 1, characterized in that, The partitioned variable temperature drying device in step (c) is divided into three independently controlled zones: first zone, temperature 60℃ and relative humidity 20%; second zone, temperature 45℃ and relative humidity 40%; third zone, temperature 25℃ and relative humidity 55%.

7. A continuous process for producing a full air permeable slow rebound sponge according to claim 6, wherein, After drying, the sponge is conditioned in an environment of 23±2℃ and 50%±5%RH for ≥16 hours.

8. The continuous production method of a full-breathable slow-rebound sponge according to claim 1, characterized in that, The cutting knife in step (d) vibrates at a frequency of 20kHz.

9. The continuous production method of a full-breathable slow-rebound sponge according to claim 1, characterized in that, The cutting table in step (d) applies a negative pressure adsorption force of 10kPa.

10. The continuous production method of a full-breathable slow-rebound sponge according to claim 1, characterized in that, The air flow speed of the air suspension stacking system in step (e) is 0.5m / s to 1m / s, and the air flow direction is perpendicular to the falling trajectory of the sponge.

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