Lingyang Packaging Technology Co., Ltd

What are the uses of PVDC film?

jason — Mon, 31 May 2021 11:34:25 GMT

PVDC film is widely used in household and supermarket food packaging because of its superior transparency, good surface gloss and good self-adhesive; PVDC preservative film can not only be used to preserve food in household refrigerators, but also be used for microwave heating, which has become one of the commonly used packaging materials in developed countries. PVDC preservative film is well known in Japan, and has developed into a mature consumer goods, with an annual consumption of more than 25000 tons; In China, due to the carcinogenic effect of DEHA plasticizer used in PVC preservative film, some production units of packaged meat products gradually use PVDC or PE preservative film. At present, all the preservative films used in Shuanghui are PVDC preservative film. With the improvement of people's living standards, quality of life and the acceleration of the pace of life, PVDC will have a great growth in the packaging of industrial fresh-keeping film and household high-grade fresh-keeping film for prepared meat.

Performance requirements of PVDC film printing ink

jason — Mon, 31 May 2021 11:34:03 GMT

1. The ink must be surface printing ink.

2. Fast drying speed of ink. At room temperature, the machine can select 60-80m / min and dry thoroughly by blowing cold air.

3. Less residual solvent. The amount of residual solvents in printing products must meet the national food hygiene standards.

4. Good ink transfer performance and good glossiness after printing.

5. The ink will not fall off after high temperature cooking above 120 ℃, the bonding fastness is good, the ink will not change color and fade.

6. The ink should be single component ink (without curing agent).

In addition, the quality guarantee period of ink should be more than half a year.

Performance comparison of several high barrier materials

jason — Mon, 31 May 2021 11:33:26 GMT

In recent years, the development of high barrier composite materials is a worldwide trend. At present, the high barrier materials in the market include aluminum foil, PVDC, EVOH coextrusion film, nylon composite film, vacuum plating SiOx film, etc. Among the above high barrier materials, aluminum foil composite film and nylon composite film are widely used in the field of flexible packaging.

Aluminum foil composite film is used as flexible packaging material, which has the advantages of high barrier performance, metallic luster, beautiful packaging effect and high temperature sterilization resistance at 121 ℃. But there are also some shortcomings: (1) the price is high: the thickness of aluminum foil in the composite film is 9 ~ 14 μ m. If it is too thin, there will be obvious pinholes, making barrier failure, and if it is too thick, the cost and price will be on the high side（ 2) Opaque: the real content can not be seen, which is contrary to consumers' consciousness and affects the sales of products（ 3) With vacuum bag, the aluminum foil will break and crack when the material is wrinkled, so that the barrier will be lost（ 4) It cannot be used for microwave heating.

Nylon composite film, EVOH coextrusion film, PVDC composite film and vacuum coated SiOx film overcome the shortcomings of aluminum foil, such as non transparent and non microwave heating. Compared with aluminum foil, nylon composite film has the advantages of low price, good transparency, softness, strong puncture resistance and poor barrier performance (see Table 3). After sterilization at 121 ℃ for 30 min, the shelf life of meat products packed in nylon cooking bags was only 2-3 weeks at room temperature, and shorter at higher temperature in summer; In addition, nylon material is a kind of hydrophilic polymer, which turns white after moisture absorption with water and steam, and its transparency and barrier properties decrease rapidly. Meat products packaged with nylon material are generally refrigerated at low temperature, and rarely stored at room temperature.

At present, there is no production of SiOx film in China. It has a common characteristic with PVDC coating film, vacuum aluminum coating film and a series of films produced by coating and evaporation methods, that is, the adhesion between coating layer and its film is limited, the coating layer is thin, and the coating is easy to crack or fall off under cooking, which makes the barrier loss. Therefore, although the resistance rate is high, it is not used for the packaging of contents that need cooking.

EVOH coextrusion film, because EVOH plastic itself has excellent gas barrier, but because it is a hydrolysate, the molecule contains a large number of hydrophilic groups, has strong hydrophilicity, absorbs water and steam, and turns white. When the ambient humidity exceeds 60% RH, its barrier performance drops sharply, and its barrier performance to water vapor is poor; In addition, EVOH coextrusion film can withstand temperature below 100 ℃. Therefore, EVOH can not be used for the packaging of products that need high temperature sterilization at 121 ℃, and it is not suitable for the packaging of products with high water content (see Figure 2).

In contrast, compared with aluminum foil, PVDC composite film is cheap, transparent, helpful for product display, and can be heated by microwave; Compared with nylon, the oxygen permeability and water vapor permeability of PVDC composite membrane are 1 / 10 ~ 1 / 5 of nylon, and do not change greatly with ambient temperature and humidity. After high temperature and high pressure sterilization, the shelf life of the packaged meat products can reach more than 6 months at room temperature; Compared with EVOH, PVDC laminated composite film can be used for packaging of high temperature cooking products, and the barrier rate changes little with humidity and temperature.

To sum up, PVDC is an excellent food packaging material, especially resistant to high temperature cooking and good barrier to oxygen, steam and various odors, which is incomparable with other plastics. Therefore, we have reason to believe that: with the development of food industry and the emergence of new packaging technology and packaging methods, PVDC laminated composite film is more and more popular in the field of food packaging, and because of its excellent performance, it will be widely used in food, medicine, chemical industry and other fields.

Development of PVDC composite membrane

jason — Mon, 31 May 2021 11:32:37 GMT

We have been studying the PVDC plastic processing technology since 1993. After fully digesting and absorbing PVDC processing technology and understanding the development trend of food packaging at home and abroad, we have been working on the research of PVDC laminated composite film since 1997. In the development process, the biggest difficulty we encountered is that the shrinkage of PVDC is too large to be compounded.

We know that as a composite substrate, it is necessary to ensure its dimensional stability to ensure the appearance flatness of composite film after composite. Because of its own characteristics and processing technology, PVDC has a high shrinkage rate of hot water at 100 ℃ and can not guarantee the normal composite and composite effect. We improve the resin formulation and control the production process, so that the shrinkage rate of resin can be reduced to a certain extent. If the conventional dry composite process is used, PVDC film must pass through 60-80 ℃ long drying path. In this case, it will still shrink greatly (see Fig. 1), but the composite film with stable size and flat surface can not be obtained. Therefore, we adopt solvent-free composite process and composite equipment. In the process of composite, because the contact time between the roller and the film is very short, the heat transmitted from the coating roller to PVDC is limited. The selection of the applicable process temperature can not only guarantee the decrease of adhesive and viscosity, but also avoid the shrinkage caused by heating during PVDC composite.

After that, how to solve the deformation and delamination of PVDC in high temperature cooking is another important topic. We have passed a lot of experiments, on the one hand, we adjust the tension of the first and second winding on the composite process equipment to make it match; On the other hand, through the interlaminar treatment and a series of experiments of adhesion, the adhesive suitable for high temperature cooking (121 ℃, 30min) was screened. The adhesive has high initial adhesion and later bonding strength. It makes PVDC in the middle layer of the composite film suffer more adhesive force than that of PVDC when it is heated and shrinks. It effectively ensures the adhesion fastness and appearance flatness of the composite film during cooking and after cooking.

With the successful adoption of these two technical measures, the technology of directly manufacturing high temperature resistant cooking composite film by PVDC is a key problem. Through several years of practice, we have made a complete technological breakthrough: according to the requirements of sterilization temperature of the compound membrane packaging content, we used CPE (< 100 ℃) and CPP (121 ℃) as the heat seal layer respectively, which effectively guaranteed the heat sealing strength; Through the improvement of PVDC processing technology, the problems of frequent bubble breaking and the yield of finished products are solved when reducing the thickness of PVDC. The thickness is less than 20 μ The cost ratio of PVDC is effectively reduced under the premise of ensuring the performance of M PVDC substrate film, so that the overall cost of PVDC composite film is reduced to the degree close to that of three layer nylon composite film. We have developed three layers of PVDC laminated film which is suitable for bag making and automatic molding machines; BOPP (or BOPET) /pvdc/cpe, three-layer high temperature laminating composite membrane: BOPP (or BOPET) /pvdc/cpp, four layer anti puncture high temperature laminating composite membrane: BOPP (or BOPET) /pvdc/bopa/cpp and other special functional PVDC composite films.

The production technology is the first in China, filling the gap in China, and has applied for the national invention patent. The PVDC laminated composite films produced are sent to the national plastic product quality inspection center and the PVDC technology center of Dow Chemical Company of the United States for comprehensive testing. All the indexes meet the requirements of the national standard GB / t10004-1998 for high temperature cooking composite film and bag (see Table 2). It has the following characteristics:

The transmission of water vapor is 4.2cm3/m2.24h.atm and 1.6g/m2.24h respectively. The shelf life of meat food packed with it can reach 6 months after being digested at high temperature (121 ℃, 30min);

The mechanical strength and barrier of the laminated composite film produced by the trampoling through sizzling yard nucleus are not reduced after sterilization at 121 ℃ and 30min, and the composite film is not deformed, cracked, and layered, and the surface is smooth and smooth, and the dimension stability is good;

The bonding strength between bopp/pvdc layers is very large and cannot be stripped after cooking, and the peel strength between layers of pvdc/cpp reaches about 5N;

4. The transparency is high, which meets the people's desire to see the contents of the package;

5. The mechanical properties and heat sealing properties are good, and can be used in many kinds of packaging machinery;

6. The composite of many kinds of substrate films, such as OPP, BOPET, BOPA, CPE, CPP, PVC, Al pet, etc;

Good stability: no chemical reaction with acid, alkali, salt, etc., and strong solvent and grease resistance.

Eight said lung Lang is good: in line with national health standards, it is non-toxic and harmless to human body.

Development of PVDC composite membrane

jason — Mon, 31 May 2021 11:32:05 GMT

With the continuous development of packaging technology, the application field of plastic composite packaging materials is expanding. It can provide high barrier plastic packaging materials with good quality, fresh-keeping, flavor and shelf life. It has been rapidly developed and widely used in the packaging industry, especially in the food packaging industry.

High barrier packaging materials usually refer to the materials with high barrier effect on gas and liquid penetrants, which are shown in the following aspects: preventing the invasion of oxygen to oxidize and deteriorate commodities; Prevent the penetration of water or steam to make the goods damp and moldy; Prevent the penetration of aroma, carbon dioxide and peculiar smell, and make the goods taste and deteriorate.

The international plastics industry is used to measure the difference of barrier properties of plastics by the physical quantity of "transmittance". Usually 25.4 μ The contrast unit is the volume (cm3) of oxygen permeating through the plastic film with a thickness of 1 m2 in 24 hours at 23 ℃, a standard atmospheric pressure, a relative humidity of 50% RH. The value below 10 is called high barrier plastic; 10-100 is called medium barrier plastic; More than 100 is called ordinary barrier plastic. At present, EVOH (ethylene vinyl alcohol copolymer), PVDC (polyvinylidene chloride) and pan (polyacrylonitrile) have been industrialized as high barrier plastics (see Table 1). PVDC and EVOH are high barrier plastics which have been put into large-scale industrial application. According to statistics, in 1992, the output of high barrier plastics in the world was 1.26 million tons, of which the output of PVDC resin accounted for 1.08 million tons, accounting for more than 80% of the total output.

PVDC is expected to replace PVC as food preservation film

jason — Mon, 31 May 2021 11:31:38 GMT

The special inspection results of PVC food fresh film recently released by AQSIQ show that some PVC fresh-keeping films used for food packaging contain DEHA plasticizer, which will have an impact on human health under certain conditions. The food preservation film of PE and PVDC materials tested at the same time is safe.

"Some enterprises have added harmful additives to human body in the production of PVC fresh-keeping film, which produces toxic substances when heated in microwave oven," said Li Chengxin, vice general manager of Xingtai Weite Plastic Co., Ltd., a joint venture between China and foreign countries. Generally, consumers can not distinguish whether the product is toxic or not according to common sense, and it is difficult to effectively supervise. So I think it is right for the state to restrict this product and find a safe alternative as soon as possible`

Some enterprises add harmful additives to human body in the production of PVC fresh-keeping film, which produce toxic substances when heated in microwave oven. Generally, consumers can not distinguish whether the product is toxic or not according to common sense, and it is difficult to effectively supervise. So the state should find security alternatives as soon as possible. " He said the national environmental protection department just asked them to provide samples of PVDC food preservation film, and said that the cooperation between the two sides will be very broad, because PE food preservation film can not meet the customer requirements well at present, and the safety of PVC food preservation film is questioned. Only PVDC film can achieve the use effect of PVC film.

PVDC film is different from the additives of PVC film. The former does not contain heavy metals and meets FDA requirements. The national environmental protection department is investigating and further understanding the properties of PVDC film of the company.

Xingtai Weite Plastic Co., Ltd. is the only enterprise in China that has PVDC co extrusion equipment, and the blowing equipment meets the normal application requirements and can be produced in batches.

PVDC will become a mainstream food packaging material

jason — Mon, 31 May 2021 11:31:04 GMT

PVDC (polyvinylidene chloride) is a kind of yellowish, powdery and high barrier material. In addition to the general properties of plastics, it also has the properties of self extinguishing, oil resistance, taste retention, excellent moisture-proof and mould proof, as well as excellent printing and heat sealing properties.

The amount of materials used in PVDC composite packaging is much less than that of ordinary PE film, paper, aluminum foil and other packaging materials, so as to achieve the purpose of reducing packaging and waste sources. In the United States, PVDC products are non-toxic and safe plastic materials, which have been widely used in food packaging; In Germany, the packaging material has a green mark; About 60% of the small package food, medicine, chemical products and electronic products in Japan and South Korea are packed with PVDC.

In view of the current situation that the level of food packaging in China is still relatively backward, relevant experts pointed out that promoting the use of PVDC materials can not only improve the level of packaging products in China, but also reduce the losses caused by product packaging, so as to enhance market competitiveness and establish a new image of enterprises. It can be predicted that in the future packaging industry, the full and reasonable use of PVDC coating film will gradually become the mainstream of China's packaging industry, and the food loss will be greatly reduced.

What is the use of PVDC casing film?

jason — Mon, 31 May 2021 11:30:43 GMT

PVDC casing film is mainly used for packaging ham sausage, high temperature sterilization, suitable for high frequency welding automatic enema machine for industrial mass production of ham sausage. This function of PVDC is mainly used in China, with annual use of PVDC resin reaching more than 30000t, such as Shuanghui, Jinluo, Yurun, Meihao, Jiangquan, etc; It is also used in a small amount abroad, such as Japan, South Korea, Vietnam, etc.

What are the common high barrier film materials?

jason — Mon, 31 May 2021 11:30:19 GMT

PVA coated high barrier film

PVA coated high barrier film is made by printing and compounding PVA coated with nano inorganic matter on polyethylene film, which solves the technical bottleneck of poor barrier performance of three-layer polyethylene co extrusion packaging film on the premise of little increase in cost. In 2008, after three years of hard work and independent innovation, the scientific research personnel of Cangzhou Jinlong Plastics Co., Ltd. finally took the lead in bringing the product with national patent, PVA coated high barrier milk film, to the market in China. The oxygen blocking rate is less than 2cm3 / (M2 · 24h · 0.1MPa), the barrier performance is not only better than EVOH five layer co extrusion film, but also the packaging cost is greatly reduced, which can not only ensure all the quality requirements of aseptic packaging, but also greatly reduce the cost of aseptic packaging in food processing enterprises, It can be used to pack drinks, juice, milk, soy sauce and vinegar.

PVDC (polyvinylidene chloride)

PVDC resin is often used as composite material, monomer material and coextrusion film sheet, which is the most widely used high barrier packaging material. Polypropylene (OPP) and polyethylene terephthalate (PET) are used as substrates for PVDC film. Due to the high softening temperature of pure PVDC, close to its decomposition temperature and poor compatibility with general plasticizers, it is difficult to heat form and apply directly. Most of the PVDC films used in practice are copolymers of vinylidene chloride (VDC) and vinyl chloride (VC), as well as films with excellent barrier properties made by copolymerization with methyl acrylate (HA).

PVDC is characterized by low permeability, barrier and chemical resistance. With the introduction and development of ham sausage processing technology, PVDC has been developed in China.

In 2002, the domestic production of PVDC was about 20000 tons. At present, it has been widely used in food, cigarette, beverage preservation and taste separation, as well as moisture-proof packaging in chemical, pharmaceutical, electronic and military industries.

The single-layer PVDC film is made by biaxial stretch blow molding. It has shrinkage, barrier and water resistance, and does not decompose under microwave heating. It is widely used in household preservative film; PVDC and polyethylene (PE), polypropylene (PP), polystyrene (HIPS) and other synthetic resin multi-layer extrusion used for vacuum dairy products, jam and other packaging, its tensile properties are good, suitable for larger volume packaging; The composite sheet of PVDC, PE and PVC is suitable for the packaging of easily hygroscopic and volatile drugs. At present, many domestic research institutions and manufacturers focus on PVDC and other resin composite laminated film technology and high temperature resistance technology of composite film.

PVDC is used in a variety of substrates, such as PE, PP, PVC, polyamide (PA), polyethylene terephthalate (PET), etc; Coating can be single-layer or multi-layer, generally single-layer coating is 2.5 μ M can have a good barrier effect.

EVOH (ethylene / vinyl alcohol copolymer)

EVOH has always been the most widely used high barrier material. The film types of this material are not only non stretching type, but also biaxial stretching type, aluminum evaporation type, adhesive coating type, etc. in biaxial stretching type, heat-resistant type is also used for aseptic packaging products.

The barrier performance of EVOH depends on the ethylene content. Generally speaking, when the ethylene content increases, the gas barrier performance decreases, but it is easy to process.

EVOH is characterized by excellent gas barrier and excellent processability. In addition, it has excellent transparency, gloss, mechanical strength, scalability, wear resistance, cold resistance and surface strength.

In the field of packaging, EVOH is made into composite film intermediate barrier layer, which is used in all hard and soft packaging; In the food industry, it is used for aseptic packaging, hot can and cooking bag, packaging dairy products, meat, canned fruit juice and condiments; In terms of non food, it is used for packaging solvents, chemicals, air conditioning structural parts, gasoline barrel lining, electronic components, etc. In terms of food packaging, EVOH plastic containers can completely replace glass and metal containers. A number of domestic aquatic companies use PE / EVOH / PA / rvoh / PE five layer coextruded film vacuum packaging for seafood export. While speeding up the research of EVOH composite films, EVOH tensile orientation is also being studied abroad. The gas barrier performance of the new EVOH films is three times that of the existing high-performance non tensile EVOH films. In addition, EVOH can also be used as a barrier material coated on other synthetic resin packaging materials to enhance the barrier performance.

Nylon packaging materials

Nylon packaging materials used to use "nylon 6". But the air tightness of nylon 6 is not ideal. There is a kind of nylon (mkd6) polycondensated from m-dimethylamine and adipic acid. Its air tightness is 10 times higher than that of "nylon 6". At the same time, it also has good transparency and puncture resistance. It is mainly used in high barrier packaging film and food soft packaging with high barrier requirements. Its food hygiene is also approved by FDA.

The biggest characteristic of the film is that the barrier does not decrease with the increase of humidity. In Europe, MXD6 nylon is widely used as a substitute for PVDC film due to its outstanding environmental protection problems. MXD6 nylon and EVOH are used as a new kind of nylon film with high barrier property. The methods of compounding include multilayer compounding, blending and stretching of MXD6 nylon and EVOH.

Inorganic oxide coating film

The so-called coating films made by coating SiOx (silicon oxide) on other substrates have attracted more and more attention in the market. In addition to silicon oxide coating, there are also alumina evaporated films. The air tightness of the coating is the same as that of the silicon oxide coating obtained by the same method.

In recent years, the technology of multilayer compounding, blending, copolymerization and evaporation has developed rapidly. High barrier packaging materials, such as EVOH, PVDC, PA, pet multilayer composites and siloxane evaporated film, have been further developed, especially the following products: MXD6 polyamide packaging materials; MXD6 polyamide packaging materials; MXD6 polyamide packaging materials; MXD6 polyamide packaging materials; MXD6 polyamide packaging materials; MXD6 polyamide packaging materials; MXD6 polyamide packaging materials; MXD6 polyamide packaging materials; MXD6 polyamide packaging materials; MXD6 polyamide packaging materials; MXD6 polyamide packaging materials; Silicon oxide thin films, etc.

In terms of use, what are the types of PVDC?

jason — Mon, 31 May 2021 11:29:31 GMT

1. PVDC resin for extrusion

Fresh keeping self-adhesive film (single film): military products, food

Composite film, food bag (single film): food, military products

Multilayer coextrusion film: food, medicine, military products, packaging and beverage

Casing film: food packaging, ham sausage, square ham, etc

2. PVDC resin for solution coating

Special coating, silver free photosensitive coating, adhesive, container spraying

3. Fiber PVDC resin

Fishing net silk, flame retardant fabric, artificial lawn

4. PVDC latex

Composite film, food packaging, military packaging, double-sided coating film, cigarette packaging, hard film composite film, drug blister packaging, aluminum foil composite, special medicine, equipment packaging, paper coating, food moisture-proof packaging.