CN1040006C - Preparation method of weather-resistant polyethylene film - Google Patents

Abstract

The invention belongs to a manufacturing method of a weather-resistant plastic film. Choose hindered amines as the main light stabilizer, use benzophenones and triazines as auxiliary light stabilizers, use phenols as antioxidants, use phthalocyanine series and azo series pigments in combination with ultraviolet light stabilizers It is formulated as a visible light regulator, with a low molecular weight polymer as a carrier. The above-mentioned light stabilizer, antioxidant and visible light regulator are added to make a masterbatch. Use polyolefin resin (polyethylene or polyethylene-based polyolefin blend) as raw material resin, add masterbatch, other additives and visible light regulators to prepare a weather-resistant polyethylene film with a service life of 2-3 years.

Description

Preparation method of weather-resistant polyethylene film

The invention belongs to a manufacturing method of a weather-resistant plastic film.

As agricultural plastic film, polyvinyl chloride resin was mainly used as raw material in the past. Although polyvinyl chloride film is more resistant to weathering and aging, it has higher tensile strength, better thermal insulation performance and easy bonding. However, because it contains a large amount of plasticizer, the volatilization of the plasticizer and the decomposition of the resin during processing and use will cause environmental pollution. Condensed water on the inner surface of the greenhouse is easy to draw out the plasticizer in the film and drip vertically, causing crop diseases. Also due to poor low temperature resistance, high temperature and easy relaxation, easy to absorb dust and high density of the film, the cost per unit area The disadvantages such as increased height and difficult storage have been gradually replaced by polyethylene film in recent years.

The weather-resistant polyethylene agricultural film released by Japanese patent JP86203147 uses resins and stabilizers as follows:

Linear low-density polyethylene (d, 0.922g/cm ³ ) 90 parts

Ethylene - vinyl acetate copolymer (sholexBM05-6) 10 parts

(VA content 5%)

UV absorber Tinuvin 326 0.8 parts

UV absorber Tinuvin 327 0.5 parts

In this technology, because the resin used is a blend of linear low-density polyethylene and ethylene-vinyl acetate copolymer, it can ensure that the film has high initial mechanical properties, but the stabilizer system is unreasonable, and it is not Using antioxidants, only two benzotriazole compounds are used as UV absorbers in the formula. Tinuvin326 and Tinuvin327 themselves have poor light stabilization effect on polyethylene, and have almost no resistance to thermal oxidation. Therefore, the resin is processed during thermal processing. Intensive thermal oxidation reaction will inevitably occur in the film, and oxygen-containing groups such as carbonyl and hydroperoxide will be generated, which will accelerate the photooxidation reaction of the film under atmospheric conditions and shorten the service life of the film. In addition, the total amount of UV absorbers used in the formula is relatively high, accounting for about 1.3% of the film weight, which increases the cost of the film. The light stabilizing performance of UV stabilizers mainly depends on the selection and coordination, and does not depend on the amount added. Proportional relationship, 1.3% has exceeded the normal addition amount.

The resin used in the weather-resistant polyethylene agricultural film introduced by Romanian patent RomRO8846 2 is MI0.3 low-density polyethylene, and the film is thicker, so the initial mechanical property value is relatively high. The main problem is that the stabilizer is not properly selected. Although a hindered amine and a benzophenone are also selected as the light stabilizer, and epoxy fatty alcohol is added as the auxiliary light stabilizer, the selected hindered amine has poor light stabilizing effect on polyethylene. There is an enhanced thermal oxidation effect during processing. Although an attempt was made to use epoxy fatty alcohol as an auxiliary light stabilizer in the formula, it could not form a synergistic system with other stabilizers, and its own poor stability to heat and light, so although the film was very thick, the weather resistance Only about two years. The total amount of all light stabilizers in this technology is as high as 5.4%, the amount of antioxidants is as high as 0.7%, and the total amount of additives is too high, reaching 14.6%, far exceeding the normal amount. The large thickness and the addition of additives are too high, which greatly increases the cost of the film and also brings difficulties to processing.

The object of the present invention is to select hindered amines as the main light stabilizer, use benzophenones and triazines as auxiliary light stabilizers, use phenols as antioxidants, and use phthalocyanine series and azo series pigments in combination with The ultraviolet light stabilizer is matched with a visible light regulator, and the low molecular weight polymer is used as a carrier, and the above-mentioned light stabilizer, antioxidant and visible light regulator are added to make a masterbatch. Use polyethylene or polyethylene-based polyolefin blends, add lubricant oleic acid amide, process modifier polyethylene wax and masterbatch to prepare a weather-resistant polyethylene film with a service life of 2-3 years.

The polyolefin resin used in the present invention is low-density polyethylene (melt index 0.2-3.0), linear low-density polyethylene (melt index 0.5-3.0), low-density polyethylene (melt index 0.2-3.0) and linear Blend of low density polyethylene (melt index 0.5-3.0). (first blend). Low density polyethylene (melt index 0.2-3.0) and ethylene-vinyl acetate copolymer (melt index 0.5-3.0, VA content 2-15%) blend (second blend). A blend of linear low density polyethylene (melt index 0.5-3.0) and ethylene-vinyl acetate copolymer (melt index 0.5-3.0, VA content 2-15%) (third blend). In the first blend, the content of linear low density polyethylene is 5-30%, in the second blend, the content of ethylene-vinyl acetate copolymer is 5-15%, in the third blend, ethylene-vinyl acetate copolymer content of 5-20%, a small amount of linear low-density polyethylene mixed with low-density polyethylene will improve the mechanical properties of the film, and the addition of ethylene-vinyl acetate copolymer mainly contributes to improving the toughness and weather resistance of the film. The base resin in the film accounts for 83-94.6%.

The matrix of the masterbatch is the carrier resin, and the carrier resin is generally a polymer with a low molecular weight or a polymer with a large alkane body index. When the carrier resin is low-density polyethylene (MI7.0), ethylene-vinyl acetate copolymer (MI2 .0) or a blend of low-density polyethylene (MI7.0) and low-density polyethylene (MI50) (the ratio of the two is 2:1), the content in the masterbatch is 80-91.4%), made into a film The masterbatch content is 5-15%.

The main ultraviolet light stabilizer used in the present invention is hindered amine light stabilizer three [1,2,2,6,6-pentamethyl-4-piperidinyl] phosphite or this light stabilizer and other hindered amine light stabilizer stabilizer. Such as the combination of Chimassorb944, Tinuvin622 and Tinuvin144. The content of the main ultraviolet light stabilizer in the masterbatch is 4-11%. The weight ratio of tris[1,2,2,6,6,-pentamethyl-4-piperyl]phosphite to Chimassorb944 or Tinuvin144 is 3:2. The auxiliary light stabilizer is a benzophenone or triazine ultraviolet light stabilizer. When the auxiliary light stabilizer is 2-hydroxy-4-n-octyloxybenzophenone or triazine-5, the content of both in the masterbatch is 1.3-2.6%, and the antioxidant is a phenolic antioxidant , when the antioxidant is 2.6-di-tert-butyl-p-cresol or β-(4-hydroxyl-3.5-di-tert-butylphenyl) n-octadecyl propionate, the content of the two in the masterbatch is 1.3%-2.6%.

The visible light mediator used in the present invention is composed of phthalocyanine series pigments, azo pigments or compound light stabilizers. When the phthalocyanine series pigments are phthalocyanine blue and the azo pigments are Fast Yellow G, the content of the two in the masterbatch Both are 0.4-0.6%.

Other auxiliary agents used in the present invention include lubricants and processing modifiers, etc., such as stearic acid amide, glyceryl stearate, oleic acid amide, ethylene bis(hydroxystearamide), stearic acid and salts thereof, Petroleum ether, paraffin, liquid paraffin, polyethylene wax, etc., when the lubricant is oleic acid amide, its addition accounts for 0.1-0.5% of the film; when the processing modifier is polyethylene wax, its addition accounts for 0.1-0.5% of the film. 0.3-1.5%, the total addition of additives should not exceed 3% of the weight of the resin. After the carrier resin, light stabilizer, antioxidant and visible light regulator are premixed, they are granulated by a kneading and granulating machine to obtain a masterbatch.

After the base material resin is mixed with the masterbatch, it is blown on the extruder according to the processing technology of the blown film method to make a polyethylene film with a thickness of 0.10-0.16mm. The processing temperature: low-density polyethylene or low-density ethylene The main blend is 150-190°C, and the linear low density polyethylene or linear low density polyethylene-based blend is 175-230°C. The inflation ratio is 1:2.5-1:3. The traction speed is 3-6m/mim, and the speed of the main engine is 80-110rpm.

The invention has a unique synergistic system of ultraviolet light stabilizer, antioxidant and visible light regulator. Compared with similar products, the synergistic system uses fewer types of stabilizers and the formula is simple. The main light stabilizer is easy to obtain, and the amount added is small. The amount of the main light stabilizer in the film and the total amount of stabilizers are much lower than the amount added in similar products, so the cost is low and it is conducive to industrial production.

The visible light regulator selected by the present invention has the characteristics of color retention during use and does not sensitize the photooxidation reaction of polyethylene, and can promote plant growth and increase production and income.

A wide range of polyolefins can be used as the base resin, and the source of raw materials is sufficient.

The "weather-resistant polyethylene film" of the present invention has a service life of 2-3 years, that is, three summers and two winters, which is longer than the current polyethylene greenhouse film and other long-life polyethylene films.

Example 1:

Low-density polyethylene (MI0.3) 91.9%

Oleamide 0.1%

Polyethylene wax 0.5%

Masterbatch 7.5%

Wherein the composition of the masterbatch is as follows:

Low-density polyethylene (MI7.0) 60%

Low-density polyethylene (MI50) 30%

Tris(1,2,2,6,6-pentamethyl-4-piperidinyl) phosphite 5%

Triazine-5 1.5%

2.6-di-tert-butyl-p-cresol 1.5%

2-Hydroxy-4-n-octyloxy-benzophenone 1.5%

Fast Yellow G 0.5%

Mix the above-mentioned base resin, oleic acid amide, polyethylene wax and masterbatch according to the proportion, and blow mold it into a 0.14mm film on a PC-65 blow molding unit (L/D 28:1).

Processing temperature parameters:

body:

Zone 1: 150-180℃

Zone 2: 150-190℃

Three zones: 170-200℃

Machine head:

  Zone 4: 170-200°C

Zone five: 160-190°C

Processing parameters:

Inflation ratio: 1:2.5-1:3

  Traction speed: 3-6m/min

Host speed 80-110rpm Example 2:

Low-density polyethylene (MI1.5%) 91.9%

Oleamide 0.1%

Polyethylene wax 0.5%

Masterbatch 7.5%

Wherein masterbatch composition and processing technology condition are with embodiment 1. Example 3:

Low-density polyethylene (MI0.3) 74%

Linear Low Density Polyethylene (MI1.5) 17.9%

Oleamide 0.1%

Polyethylene wax 0.5%

Masterbatch 7.5%

Wherein the composition of the masterbatch is as follows:

Ethylene-vinyl acetate copolymer (MI2.0) 91%

Tris[1,2,2,6,6-pentamethyl-4-piperidinyl]phosphite 3%

HALS Chimassorb 944 2%

2-Hydroxy-4-n-octyloxy-benzophenone 1.5%

β-(4-Hydroxy-3,5-di-tert-butylphenyl)propanoic acid n-octadecyl

Alcohol Esters 2%

Phthalocyanine 0.5%

Processing technology condition is with embodiment 1. Example 4:

Low-density polyethylene (MI1.5) 74%

Linear Low Density Polyethylene (MI1.5) 17.9%

Oleamide 0.1%

Polyethylene wax 0.5%

Masterbatch 7.5%

Wherein the composition of the masterbatch is the same as in Example 3, and the processing conditions are the same as in Example 1. Embodiment 5: Low-density polyethylene (MI0.3) 74%

Ethylene-vinyl acetate copolymer (MI2.0) 17.9%

Oleamide 0.1%

Polyethylene wax 0.5%

Masterbatch 7.5%

Wherein the composition of the masterbatch is as follows:

Low-density polyethylene (MI7.0) 90%

Tris[1,2,2,6,6-pentamethyl-4-piperidinyl]phosphite 3%

HALS Tinuvin 144 2%

2-Hydroxy-4-n-octyloxybenzophenone 1.5%

β-(4-Hydroxy-3,5-di-tert-butylphenyl)propionic acid

                                                                                                                                                            

Triazine-5 1.5%

Fast Yellow G 0.5%

Processing technology condition is with embodiment 1. Embodiment 6:

Low Density Polyethylene 74%

Ethylene-vinyl acetate copolymer (MI2.0) 17.9%

Oleamide 0.1%

Polyethylene wax 0.5%

Masterbatch 7.5%

Wherein the composition of the masterbatch is the same as in Example 5. Processing technology condition is with embodiment 1. Embodiment 7:

Linear Low Density Polyethylene (MI1.5) 91.6%

Oleamide 0.1%

Polyethylene wax 0.8%

Masterbatch 7.5%

Wherein the composition of the masterbatch is as follows:

Ethylene-vinyl acetate copolymer (MI2) 90%

Tris[1,2,2,6,6-pentamethyl-4-piperidinyl]phosphite 5%

2-Hydroxy-4-n-octyloxybenzophenone 1.5%

β-(4-Hydroxy-3,5-di-tert-butylphenyl)propanoic acid n-deca

                                                             

Triazine-5 1.5%

Fast Yellow G 0.5%

Mix the above-mentioned base resin, oleic acid amide, polyethylene wax and masterbatch according to the proportion, and blow them into a film of 0.13mm on TOMI 60 blow molding unit (L/D 25:1).

Processing temperature parameters:

Body: Zone 1: 175-195°C

  Zone 2: 185-210°C

Three zones: 190-230℃

Machine head: Four zones: 190-230°C

Zone Five: 190-220℃

Processing parameters:

Inflation ratio: 1:2.5-1:3

Traction speed: 3-6m/min

Host speed: 80-110rpm Example 8:

Linear low-density polyethylene (MI1.5) 82.4%

Ethylene-vinyl acetate copolymer (MI2.0) 9.2%

Oleamide 0.1%

Polyethylene wax 0.8%

Masterbatch 7.5%

Wherein the composition of the masterbatch is as follows:

Low-density polyethylene (MI7.0) 91%

Tris[1,2,2,6,6-pentamethyl-4-piperidinyl]phosphite 5%

β-(4-Hydroxy-3.5-di-tert-butylphenylpropionic acid

                                                                                                                                         

Phthalocyanine Green 0.5%

2-Hydroxy-4-n-octyloxybenzophenone 1.5%

Processing technology condition is with embodiment 7.

Claims (1)

1. the manufacture method of a weather resistant plastic film is characterized in that this film forms (in weight %) by following component:

Polyolefin resin 83-94.6, masterbatch 5-15, auxiliary agent comprise lubricant 0.1-0.5, modifier 0.3-1.5; Masterbatch comprises vector resin 90, wherein vector resin is new LDPE (film grade) MI7.0, ethylene-vinyl acetate copolymer MI2.0 or new LDPE (film grade) MI7.0 and new LDPE (film grade) MI50 blend, both are than being 2: 1, main UV light stabilizing agent 4-11, fill-in light stablizer are cooperated with triazines as light stabilizer by benzophenone and form, and both are 1.3-2.6 by content in masterbatch, oxidation inhibitor 1.3-2.6, visible light conditioning agent 0.4-0.6.