KR0179079B1 - Method of making master batch for plastics - Google Patents

Abstract

The present invention relates to a method for manufacturing a master batch for starch filled degradable plastics, unlike starch and general purpose, in which an acrylic acid is copolymerized with ethylene and applied to starch in an existing improvement method for improving compatibility between starch and general resin. A starch-acrylic low-temperature copolymer prepared by grafting starch-acrylic low-temperature copolymers with starch and acryl monomer having good compatibility with all resins at room temperature of -70 ° C. without collapse of starch inherent granules was prepared. It is used as a biodegradable filler with excellent compatibility with general-purpose resins, and 5-80 parts by weight of such biodegradable fillers, 20-90 parts by weight of each general-purpose resin or mixture thereof, 0.1-15 parts by weight of auto oxidizer, and internal lubricant 0.5-20 By mixing the parts by weight and using them as the composition of the master batch, the cost burden is low. As will production method of a useful starch degradable plastic for the master batch to obtain the enhancing effect.

Description

Manufacturing method of master batch for starch filled degradable plastic

The present invention relates to a method for producing a starch-filled degradable plastic masterbatch applicable to general-purpose plastics and degradable by microorganisms during soil reclamation. Plastics have been used in a variety of everyday life with excellent functions such as processability, durability, and chemical resistance, and the amount of use has also increased steadily, but the seriousness of environmental pollution due to plastic waste is increasing day by day. Therefore, as part of such measures, domestic studies and commercialization have been actively conducted to develop plastic substitutes capable of degrading or degrading plastics.

The degradable plastics technology to date can be classified into three categories as follows. In other words, the photodegradation that causes plastic degradation by light, biodegradability that can be completely decomposed in soil by fermentation or chemical synthesis, and biodegradable natural polymers such as starch, etc. Biodegradability in the sense of imparting a resolution to the can be roughly classified, and some of them take a mixed form. However, in view of the current waste treatment form, cost, processability and applicability among these degradable plastics, the commercialization of biodegradable plastics using rich and inexpensive starch is very active in view of the fact that the application effect is the fastest. It is done.

However, in general, starch is applied to general-purpose plastics because of incompatibility between hydrophilic starch and hydrophobic general-purpose plastics, starch-containing water content, starch particle size when applied to film, and so on. We show limit of application.

Existing researches for improving the above problems include a method of using amylose starch having a straight chain structure in starch (USPat 3891620, E. Pat. 0375831A1), polyethylene, polypropylene, etc. in addition to general methods such as refinement and drying of starch. A method of copolymerizing acrylic monomers such as acrylic acid or alkyl acrylate and mixing the copolymer with starch (US Pat. 4133784, 5087650) provides starch with hydrophobicity through silicone treatment, thereby making it compatible with general-purpose plastics. There are methods to increase (US Pat. 4125495, G. Pat. 1487050), but these methods have high manufacturing costs or extremely limited improvements in plastic properties, which can lead to significant improvements in properties or increased starch charge. Is not.

Accordingly, it is an object of the present invention to provide a method for producing a starch-filled degradable plastic masterbatch which can improve the physical properties and starch filling amount of the degradable plastics over existing methods.

That is, according to the present invention, a starch-acrylic copolymer is prepared by reacting an acrylic monomer having good compatibility with a general-purpose resin at low temperature to maintain starch-acrylic copolymer without swelling the starch. And a method of preparing a starch-packed degradable plastic masterbatch using a composition mixed with a lubricant and the like, and a marked improvement in physical properties and starch filling amount can be obtained.

Referring to the method for producing a degradable plastic master batch according to the present invention in more detail.

That is, as a method for preparing a starch-acrylic low temperature copolymer, one of acrylic monomers such as acrylamide, acrylic acid, acrolein, and alkyl acrylate is selected and adjusted to 10-150% (W / W) for starch, and then starch and Dissolve in water together and mix radical initiators such as ammonium persulfate, potassium permanganate and peroxide at 0.5-5% with respect to starch as reaction catalyst, and graft reaction between starch and acrylic monomer in room temperature -70 ℃ do. At this time, it is also preferable to add adipic acid in the range of 0.5-3% to the starch as the radical initiation aid. When the reaction rate is higher than 65 ° C or higher, it is necessary to add sodium chloride or sulfate to suppress the swelling of the starch. Assuming that the total composition of the degradable masterbatch is 100 parts by weight, 5-80 parts by weight of the product obtained by this method, 20-90 parts by weight of general-purpose resin, 0.1-15 parts by weight of auto oxidant and 0.5-20 parts by weight of internal lubricant The master batch for starch-filled degradable plastics in pellet form was prepared using an extruder and pelletizer after melting and mixing. In addition, the use of starch-acrylic copolymer as a composition can be mixed with general starch, and the most preferable mixing ratio is starch-acrylic copolymer: general starch is 10: 2-10: 10 (W / W). In the case of the film, the lower the mixing ratio of the general starch, the better the physical properties.

The starch used in the present invention is potato starch, corn starch, sweet potato starch, wheat starch, waxy corn starch, tapioca starch, modified starch, ie oxidation starch, acid treated starch, ester starch, ether starch, crosslinked starch, hydroxy Alkyl starch and a starch of these or mixtures thereof can be used.

The automatic oxidizing agent used in the present invention generates radicals by reacting with transition metals in the soil and shortens the decomposition period of undecomposed resin residues by breaking down the bonds between carbons in contact with the remaining resin residues. The main ingredient is unsaturated fatty acid-containing substances or monounsaturated fatty acids and ester salts thereof, which may be used alone or in combination with rapeseed oil, corn oil, oleic acid, oleic acid chloride, oleic acid, linolenic acid, and sodium oleate, alkyl oleate. In the present invention, the internal lubricant may be used alone or in a mixture of liquid paraffin, paraffin chloride, normal paraffin and paraffin wax to improve physical properties and workability of the degradable plastic product.

On the other hand, the general purpose resin is low density polyethylene (LDPE), linear low density polyethylene (LLDPE), high density polyethylene (HDPE), polypropylene (PP) and polystyrene, etc. Good compatibility with the use of the matrix resin depending on the type and combination conditions can be used in a variety of good physical properties for the production of various films, disposable packaging materials and plastic molded products decomposed under the presence of microorganisms.

As described above, the present invention uses acryl monomer having good compatibility with both starch and general resin, and the existing method (US Pat. 4133784, 5087650) is used by copolymerizing acrylic acid with ethylene. It was made to react at low temperature without disrupting the granule shape of starch to achieve compatibility between starch-acrylic copolymer and general purpose resin. It is easier to manufacture and cheaper than ethylene-acrylic acid copolymer, which is expensive and inexpensive. It is unusual to extend the limit of the amount of starch filling according to the improvement effect.

Hereinafter, the present invention will be described in detail with reference to Examples for a degradable film, but the present invention is not limited thereto.

Example 1

[Preparation of Starch-Acrolein Low Temperature Copolymer]

1 kg of 12.7% water starch is added to 3 L of water and stirred to form a starch suspension, followed by stirring with 600 g of acrolein and 50 g of sodium sulfate. Subsequently, 4 g of ammonium persulfate and 10 g of adipic acid were further added, followed by reaction at a reaction temperature of about 68 ° C. to prepare a starch-acrolein low-temperature copolymer that maintains the desired starch granule after washing and drying.

[Preparation of Masterbatch for Starch Filled Degradable Plastics]

Example 2

70 parts by weight of dried starch-acrolein low temperature copolymer prepared by the same method as in Example 1, 15 parts by weight of low density polyethylene, 10 parts by weight of linear low density polyethylene, 3 parts by weight of seed oil and 2 parts by weight of liquid paraffin at 20 ° C. After melting and mixing for a minute, a masterbatch was prepared using an extruder and a pelletizer.

Example 3

A masterbatch was prepared in the same manner as in Example 2 using 70 parts by weight of mixed starch, in which 35 parts by weight of starch-acrolein low-temperature copolymer and 35 parts by weight of normal starch were mixed.

[Preparation and Evaluation of Starch Filled Biodegradable Films]

Example 4

After mixing the masterbatch prepared in Example 2 so that the linear low density polyethylene had a starch content of 10%, a starch-filled biodegradable film was prepared using a blown film extruder in a temperature range of 160 ° C to 180 ° C, and evaluated for physical properties and degradability. It was. The physical properties of the film were measured according to the standard of KSM3509 and the degradability evaluation was tested for biodegradability according to the method of ASTM G21-70.

Example 5

After mixing the masterbatch prepared in Example 3 to have a starch content of 10% in the linear low-density polyethylene, starch-filled biodegradable films were prepared in the same manner as in Example 4 below, and physical properties and degradability were evaluated.

Example 6

After the master batch prepared in Example 2 was mixed with the linear low density polyethylene to have a starch content of 15%, starch-filled degradable films were prepared in the same manner as in Example 4 below, and physical properties and degradability were evaluated.

The results of comparing the physical properties and degradability of the films prepared in Examples 4, 5, and 6 with pure normal starch using films (starch content 10%) are shown in Table 1.

As described above, the starch-filled biodegradable film prepared by using the masterbatch prepared according to the present invention has a generally good result in tensile strength, tear strength, and elongation rate, compared to the control using pure starch. In addition, it is possible to increase the amount of starch filling while improving the biodegradability.

Claims (7)

5-80 parts by weight of biodegradable filler, starch-acrylic low temperature copolymer alone or a mixture of starch-acrylic low temperature copolymer and starch, 20-90 parts by weight of general-purpose resin, 0.1-15 parts by weight of automatic oxidizer and 0.5-20 parts by weight of internal lubricant A method of producing a master batch for starch packed decomposable plastics, characterized in that the part is melted and mixed as a composition. According to claim 1, starch-acrylic low-temperature copolymer dissolves 10-150% (W / W) of the acrylic monomer with starch in water with starch and persulfate at a low temperature range of room temperature -70 ℃ without collapse of the starch granules Starch-packed degradable plastic master batch characterized in that the starch-acrylic low-temperature copolymer grafted starch and acrylic monomer by mixing reaction catalysts such as ammonium, potassium permanganate and peroxide with 0.5-5% (W / W) Manufacturing method. The starch according to claim 1 or 2, wherein the starch is potato starch, corn starch, sweet potato starch, wheat starch, waxy corn starch, tapio starch, modified starch thereof, that is, oxidized starch, acid treated starch, ester starch, ether starch, A cross-linked starch, a hydroxyalkyl starch, and a a starch of these, or a mixture thereof. The method of claim 1, wherein the general purpose resin is low density polyethylene, linear low density polyethylene, high density polyethylene, polypropylene, polystyrene, or a mixture thereof. The method according to claim 1, wherein the automatic oxidizing agent is an unsaturated fatty acid-containing material or a monounsaturated fatty acid and its ester salts such as rapeseed oil, corn oil, oleic acid, oleic acid chloride, olenic acid, linolenic acid, sodium oleate, alkyloleate or mixtures thereof. A method for producing a master batch for starch filled degradable plastics, characterized in that The method of claim 1, wherein the internal lubricant is liquid paraffin, paraffin chloride, normal paraffin, paraffin wax or mixtures thereof. The method of claim 2, wherein the acrylic monomer is acrylamide, acrylic acid, acrolein, alkyl acrylate or a mixture thereof.