What is solvent-free compounding  technology?

Solvent-free compounding is also a kind of dry compounding in a broad sense, that is, a process in which a 100% solid solvent-free adhesive is used to compound flexible packaging substrates on a special compounding machine without solvent.

In 1974, the German Herberts company first began to industrially produce one-component moisture-curing solvent-free adhesives, and manufactured flexible packaging composite materials, and solvent-free composite materials were officially born. In the end, solvent-free compounding has achieved rapid development, especially in European and American countries, solvent-free compounding has accounted for 60% of the production of composite membranes. Environmental protection is the driving force behind the development of solvent-free compounding, and its low cost is also another factor in the development of solvent-free compounding. Because of this, solvent-free compounding has also been widely used in areas where environmental legislation is not yet strict.
Compared with solvent dry compounding ratio, solvent-free compounding has distinct advantages and disadvantages.
(1) Protect the environment

In addition, because of its structural size and reduced box, the noise of solvent-free equipment is much lower than that of solvent-based equipment. According to actual measurements, the secret sound of solvent-free composite equipment is generally between 70~75dB, and solvent-based equipment is generally 85~ Between 100dB
(2) Low cost

In terms of equipment investment cost, due to the close proximity of solvent-free composite equipment, it is approximately significantly smaller than solvent-based composite equipment, and the cost of the equipment itself is much lower.
Sub-solvent-type equipment does not require solvent warehouses. In terms of energy costs, solvent-free equipment does not have a drying tunnel, saving 200~300kg/h of steam, and the motor power of the equipment is reduced by tens of kilowatts compared with solvent-type equipment. Above, solvent-free compound equipment generally only needs to be equipped with 1~2 people/set, while solvent-based compound equipment needs to be configured with 2~3 people/set. In terms of adhesive cost, the amount of glue is only 2/3 of the solvent type. It will reduce the production cost in mass production. In addition, there is no need to invest in solvent recovery and incineration equipment
(3) Hygiene and safety

No matter how to control the solvent-based compound, there will always be residual solvents, while the solvent-free compound avoids the residual solvents to contaminate the contents or cause peculiar smells, and the operation is safe. Since the use of solvents is free, there is no risk of fire or explosion. No protective measures required
(4) Product quality

As a result, the substrates of ordinary composite films can be produced with solvent-free adhesives, and even composite films that can withstand high-temperature cooking at 121°C can also be manufactured by this method.
(5) Disadvantages of solvent-free compounding. The entire system needs to be heated when the adhesive is replaced, and the replacement machine needs to be insulated: the pot life after the adhesive is mixed is short, and the effective use time is not more than 30 minutes; High-temperature sterilization products are still difficult to meet the requirements; the initial viscosity is low, and the curing time is long; the replacement accuracy is high. As the name implies, the solvent-free composite adhesive is 100% solid and has no volatile substances.

Features of solvent-free compound equipment
The solvent-free compounding equipment is relatively simple and compact. It is mainly composed of two unwinding devices, one winding device, adhesive dispensing replacement device and compounding device. The adhesive can be evenly distributed on the surface of the material. Therefore, the biggest feature of the solvent-free composite equipment is the glue system. The solvent-free gluing system uses the speed difference ratio of each roller to meet the requirement of very low filling volume. The multi-system generally has 4 rollers, two metering rollers, one transfer roller, one gluing, the transfer roller is rubber, the first roller has a slower speed, and the last roller is the replacement roller speed shift, which is consistent with the compound speed. Due to the different roller speeds and the fracture pressure between the rollers, the adhesive is added between the first two rollers and the glue roller must be squeezed and sheared many times at the end. The adhesive layer on the rollers becomes thinner step by step. This guarantees a certain amount of glue.

Because the contact between each is required to be very close, it is necessary to use very precise rollers and bearings. It should reach 0.102um when inserted, and the thickness of chrome plating is 0.102-0.25mm. If the ratio of the length to the diameter of the sub is 8:1, the error in straightness and concentricity must be less than 3.8um, and the rubber is replaced by abrasion-resistant and solvent-resistant rubber, and it is quite stable and elastic , The thickness is at least 19.8mm, and the rubber hardness is 80~90 parts hardness.
The precise temperature required for cloth removal is achieved by an automatic temperature control system using water as the medium, and the water temperature error can be controlled within ±0.5°C.

The adjustment of the insertion amount is adjusted by the speed ratio change between the roller 2 and the roller 4 and the temperature stability. Therefore, the DCM design of the roller 2 and the roller 4 is controlled by an alternating DC motor to maintain the parts that are not related to the composite speed. The speed ratio between the rollers, when the machine speed is 150m/min, that is, the speed of roller 4 is 150m/min, and the speed of adjusting roller 2 is 12.5m/min, and the speed ratio is 1:12, 0.8g/㎡. To obtain a higher replacement amount, such as 1g/㎡, the speed of roller 2 should be increased to 15m/min, that is, the speed ratio is 1:10.

Company Profile

Nanjing Sumino Precision Machinery Co., Ltd. is a high-tech enterprise integrating scientific research, production and sales. It has always adhered to the business philosophy of integrity, equality, and customer benefits. In order to better improve the quality of equipment, it has entered a more professional and standardized Production track. We have established independent research and development technologies for seven categories of equipment including plastic sheet material, casting, bi-stretching, non-woven non-woven meltblown cloth, laminating film composite, recycled granulation environmental protection recycling system and coating machine manufacturing system. The center and production department provide a full set of professional technical solutions to meet the special needs of each customer. Among them, the biaxially oriented film manufacturing system includes: BOPP biaxially oriented film manufacturing system, PVC biaxially oriented shrink film production line, PET biaxially oriented film production line, BOPA biaxially oriented film production line, BOPA biaxially oriented film production line, etc.

Company Address: No. 11, Kaifeng Road, Moling Street, Jiangning District, Nanjing City, Jiangsu Province