CN111907083A - Tray and preparation method thereof - Google Patents
Tray and preparation method thereof Download PDFInfo
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- CN111907083A CN111907083A CN201910386118.5A CN201910386118A CN111907083A CN 111907083 A CN111907083 A CN 111907083A CN 201910386118 A CN201910386118 A CN 201910386118A CN 111907083 A CN111907083 A CN 111907083A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/001—Combinations of extrusion moulding with other shaping operations
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/001—Combinations of extrusion moulding with other shaping operations
- B29C48/0018—Combinations of extrusion moulding with other shaping operations combined with shaping by orienting, stretching or shrinking, e.g. film blowing
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/25—Component parts, details or accessories; Auxiliary operations
- B29C48/92—Measuring, controlling or regulating
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L97/00—Compositions of lignin-containing materials
- C08L97/02—Lignocellulosic material, e.g. wood, straw or bagasse
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
- B29L2031/00—Other particular articles
- B29L2031/712—Containers; Packaging elements or accessories, Packages
- B29L2031/7178—Pallets
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2205/00—Polymer mixtures characterised by other features
- C08L2205/02—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2205/00—Polymer mixtures characterised by other features
- C08L2205/03—Polymer mixtures characterised by other features containing three or more polymers in a blend
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2205/00—Polymer mixtures characterised by other features
- C08L2205/03—Polymer mixtures characterised by other features containing three or more polymers in a blend
- C08L2205/035—Polymer mixtures characterised by other features containing three or more polymers in a blend containing four or more polymers in a blend
Abstract
The invention relates to the field of tray manufacturing, and discloses a tray and a preparation method thereof, wherein the preparation method comprises the following steps: 1) sequentially granulating, first extruding and first forming the raw materials to obtain a rough blank; 2) heating the rough blank to the softening point of the raw materials, and then performing second extrusion through an oriented stretch film opening to obtain an extruded material; 3) sequentially stretching and second forming the extruded material; wherein the difference between the speed of the second extrusion and the speed of the stretching is 1-15 m/min. The tray prepared by the method has the characteristics of high strength, low water absorption, small density and light weight.
Description
Technical Field
The invention relates to the field of tray manufacturing, in particular to a method for preparing a tray and the tray prepared by the method.
Background
Preliminary investigation of the China Committee for Pallet Special Committee of Committee for Logistics and procurement: china now has about 5000-7000 million trays of various kinds, and the annual output increases by about 2000 million. Wherein the wooden flat pallet accounts for about 90 percent, the plastic flat pallet accounts for 8 percent, and the steel pallet, the composite material pallet and the paper pallet account for 2 percent in total. The composite tray and the plastic tray have a large rising ratio.
Wooden pallets are made of wood or bamboo materials and are generally used for containing artware or used for decoration. The metal tray is generally made of stainless steel, is mainly used for placing articles and is not frequently moved. The plastic tray is light in texture, convenient to use, has an anti-skid function, and is widely applied to the service industry. The plastic-wood pallet is made of plastic-wood composite materials, has wide application, saves energy and reduces pollution.
Most of plastic trays in the prior art are low in strength, cannot meet the application requirements, and are poor in waterproof performance, low in strength and poor in durability.
Therefore, there is a need for a pallet that can better reduce logistics costs while providing a pallet that is lightweight, inexpensive, strong, and durable.
Disclosure of Invention
In order to overcome the defects of high water absorption rate, low strength and heavy weight of the tray in the prior art, the invention provides the method for preparing the tray, and the tray prepared by the method has the characteristics of high strength, low water absorption rate, low density and light weight.
The inventor of the present invention found in research that after heating the raw blank to the softening point of the raw material, the raw material is oriented by orienting the stretching film opening, and the rate difference between the second extrusion rate and the stretching rate is controlled to be 1-15m/min, so that micropores are formed in the raw blank, and then cooling and second forming are performed, so that the prepared tray has good properties of low density, light weight, high strength and low water absorption.
In order to achieve the above object, a first aspect of the present invention provides a method of preparing a tray, the method comprising:
1) sequentially granulating, first extruding and first forming the raw materials to obtain a rough blank;
2) heating the rough blank to the softening point of the raw materials, and then performing second extrusion through an oriented stretch film opening to obtain an extruded material;
3) sequentially stretching and second forming the extruded material;
wherein the difference between the speed of the second extrusion and the speed of the stretching is 1-15 m/min.
In a second aspect, the invention provides a pallet produced by the method of the first aspect of the invention.
Through the technical scheme, the tray prepared by the invention has the characteristics of high strength, low water absorption and light weight.
Detailed Description
The following describes in detail specific embodiments of the present invention. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.
The present invention provides in a first aspect a method of making a tray, the method comprising:
1) sequentially granulating, first extruding and first forming the raw materials to obtain a rough blank;
2) heating the rough blank to the softening point of the raw materials, and then performing second extrusion through an oriented stretch film opening to obtain an extruded material;
3) sequentially stretching and second forming the extruded material;
wherein the difference between the speed of the second extrusion and the speed of the stretching is 1-15 m/min.
To further obtain a lighter weight tray, preferably the difference in the speed of the second extrusion and the stretching is 3-9 m/min.
The softening point of the invention is about 5 ℃ above and below the Vicat softening point of the raw materials.
In the present invention, the granulation method described in step 1) is not particularly limited, and granulation can be performed by a conventional method in the art.
According to a particular embodiment, granulation may be carried out using a twin-screw granulation process. Specifically, the twin-screw granulation method comprises the following steps:
a. weighing the raw materials, and feeding the raw materials into a double-screw hopper through a feeding screw;
b. then extruding the mixture by a double-screw extruder, wherein the extrusion temperature is 150-250 ℃;
c. passing through a granulator to obtain raw material particles.
In step 1) of the present invention, the method for obtaining a rough blank comprises:
i. and (3) adding the raw material particles obtained after granulation into a large-scale plate extruder, and performing first extrusion through a die of the mother blank, wherein the heating area of the die is divided into eight areas, and the heating temperature is 200-250 ℃.
For better performing the subsequent stretching step, obtaining a lightweight tray, preferably the conditions of said first extrusion comprise: the extrusion temperature is 110-150 ℃, the extrusion speed is 0.5-10m/min, and the extrusion speed is 3-8m/min is further preferred;
cooling the extruded mother blank and performing first forming to form a rough blank with stable dimension.
In the step 2), the rough blank is heated to the softening point of the raw material and then conveyed to an oriented stretch film opening through a crawler belt or a guide roller for second extrusion, and the stretch film opening is heated in seven regions at the temperature of 130-.
In the step 2), the heating mode for heating the raw material to the softening point can be oil bath hot roller or infrared radiation closed heating mode, and the infrared heating zone is arranged in seven zones at the temperature of 180-300 ℃.
According to the invention, after the rough blank is heated to the softening point of the raw material, the raw material is enabled to have certain orientation through the orientation stretching film opening, the speed difference between the second extrusion speed and the stretching speed is controlled to be 1-15m/min, so that micropores are formed in the rough blank, and then cooling and second forming are carried out, thus obtaining the tray. Controlling the rate difference between the second extrusion and the stretching enables the resulting pallet to be less dense and lighter in weight, while having good properties of high strength and low water absorption.
The softening point of the invention is about 5 ℃ above and below the Vicat softening point of the raw materials.
According to a specific embodiment, the cooling mode of the invention can be a cooling roller with a cooling medium flowing through, or can be cooling medium showering; the temperature of the cooling medium can be-5-35 ℃; the cooling medium may be one or more selected from water, brine, and ethylene glycol.
In order to further improve the strength of the tray prepared by the method of the invention and reduce the water absorption rate of the tray, preferably, the raw material is a polyolefin composition, the composition contains polyethylene, styrene elastomer and filler, the styrene elastomer is a block copolymer of styrene and conjugated diene, the content of the styrene elastomer is 3-90 parts by weight and the content of the filler is 50-200 parts by weight relative to 100 parts by weight of the polyethylene.
Further preferably, the content of the styrenic elastomer is 40 to 80 parts by weight and the content of the filler is 120-180 parts by weight with respect to 100 parts by weight of the polyethylene.
In the present invention, preferably, the conjugated diene is at least one selected from butadiene, isoprene, and myrcene.
In order to further improve the strength and reduce the water absorption of a tray containing the composition, it is preferable that the styrene-based elastomer in the composition is a triblock copolymer of styrene and butadiene, and the triblock copolymer is an SEBS structure.
In the invention, the SEBS structure refers to hydrogenation reaction of SBS structure of triblock copolymer of styrene and butadiene, so that polybutadiene chain segment of the triblock copolymer only contains unsaturated double bonds with 1, 2-structures.
According to the present invention, preferably, the triblock copolymer is prepared by anionic polymerization. The present invention has no particular limitation on the specific operating conditions for preparing the triblock copolymer by anionic polymerization, and those skilled in the art can perform the polymerization by using various operating conditions conventional in the art, and the present invention will not be described herein again, and those skilled in the art should not be construed as limiting the present invention. For example, the triblock copolymer of styrene and butadiene may be prepared by:
dissolving styrene in a cyclohexane solvent, adding an initiator n-butyllithium, carrying out a polymerization reaction at 50 ℃, adding 1, 3-butadiene at the rate of 1-3kg/min after the reaction is finished, and reacting for a period of time at the temperature of 50-55 ℃ to prepare the styrene-butadiene-styrene triblock copolymer with the SBS structure. Then, a catalyst Ti/Al (Ti/Al molar ratio is 1: 1.7) is used for hydrogenation reaction under the condition that the hydrogen pressure is 4.5-5MPa, and the triblock copolymer with the SEBS structure is prepared.
Preferably, the molecular weight of the triblock copolymer is from 5 to 15 million, more preferably from 8 to 9 million. Controlling the molecular weight of the triblock copolymer is beneficial to controlling the processability of the composition. It is well known to those skilled in the art that triblock copolymers prepared using anionic polymerization have weight average molecular weights equal to number average molecular weights.
In the present invention, it is preferable that the content of the polystyrene segment in the triblock copolymer is 20 to 30% by weight based on the total weight of the triblock copolymer.
Preferably, the content of 1, 2-structural units in the polybutadiene block is not higher than 15% by weight, more preferably 8 to 12% by weight, based on the total weight of the polybutadiene block in the triblock copolymer.
In the present invention, in order to improve the strength and reduce the water absorption of the tray prepared from the composition of the present invention, the polyethylene is preferably a homopolymer of ethylene and/or ethylene and C3-8Copolymers of olefins, more preferably of said ethylene with C3-8Copolymers of olefins.
In the present invention, preferably, C is3-8The olefin is selected from at least one of propylene, 1-butene, 1-hexene and 1-octene.
According to the invention, the polyethylene preferably has a content of ethylene and other copolymerized olefins such that the polyethylene has a melt flow rate of (0.5 to 3) g/10min at 230 ℃ under a load of 2.16 kg.
In order to further reduce the water absorption of the tray prepared from the composition, preferably, the polyethylene has a density of (0.930-0.965) g/cm3。
In the present invention, preferably, the filler is at least one of wood flour, bamboo powder, talc powder and calcium carbonate, and the fillers are all selected conventionally in the art and are all commercially available.
The Vicat softening point of the polyolefin composition of the present invention is 115-135 ℃.
According to a preferred embodiment of the present invention, in the method for manufacturing a tray, the tray is manufactured using a polyolefin composition containing polyethylene, a styrenic elastomer and a filler as a raw material. Wherein the styrene elastomer is a triblock copolymer of styrene and butadiene, the triblock copolymer is an SEBS structure, and the content of a polystyrene chain segment in the triblock copolymer is 20-30 wt% based on the total weight of the triblock copolymer; in the triblock copolymerThe content of 1, 2-structural units in the polybutadiene chain segment is not higher than 15 wt% based on the total weight of the polybutadiene chain segment, a rough blank containing the composition is heated to the softening point of the raw material, the raw material is oriented by orienting and stretching a film opening, the rate difference between the second extrusion rate and the stretching rate is controlled to be 3-9m/min, micropores are formed in the rough blank, and then cooling and second molding are carried out, so that the density of the prepared tray is 0.2-1.0g/cm3The tray is lighter in weight, and has good properties of high strength and low water absorption.
According to the invention, the composition may also comprise other adjuvants. The auxiliaries include, but are not limited to, crosslinking agents, grafting aids, antioxidants, viscosity modifiers, light aging inhibitors, heat stabilizers, mold release agents, nucleating agents, and the like. Antioxidants such as 1076, 168. The above-mentioned auxiliaries may be added in an amount conventional in the art, for example, the above-mentioned auxiliaries may be added in an amount of 0.005 to 2% by weight based on the total amount of the polyethylene, the styrenic elastomer and the filler in the composition.
In a second aspect, the invention provides a pallet produced by the method of the first aspect of the invention.
Preferably, the density of the tray is 0.2-1.0g/cm3The density of 0.2-0.4g/cm can be obtained by optimizing the raw materials and the operation process3The tray of (1).
The pallet with stable performance obtained by stretching is cut and processed to form pallets with various shapes which can be circulated and circulated, and market requirements are met.
Through the technical scheme, the tray prepared by the invention has the characteristics of high strength, low water absorption, small density and light weight, and has wide application in the market.
The present invention will be described in detail below by way of preparation examples and examples, but the present invention is not limited thereto.
In the following examples and comparative examples,
1. mechanical properties
Testing tensile breaking stress and breaking strain according to GB/T1040-2006, wherein the thickness of a sample is 1.0mm, the sample preparation condition is 210 ℃ tabletting, preheating is carried out for 6 minutes, pressurizing is carried out for 4 minutes under 5MPa, cooling is carried out for 4 minutes under 10MPa, the sample is cut into a II-type dumbbell sheet sample by using a sample cutter, and the tensile speed is 50mm/min during testing; flexural modulus was tested according to GB/T9341-2000;
2. the density of the tray is tested according to GB/T1033-1986 (method D) and GB/T1033-2008 (method A);
3. the Vicat softening point temperature is tested according to GB/T1633-2000 (A120 method);
4. the melt flow rate is measured according to the method specified in GB/T3682-2000, specifically, the test temperature is 230 ℃, and the load is 2.16 kg;
5. the water absorption of the tray is measured according to the GB/T11547 standard;
6. the tensile strength of the tray is measured according to the GB/T1040.2 standard (wherein the tensile strength of the tray refers to the tensile strength of a sample bar prepared by the same method by using the same raw materials);
7. the impact strength of the tray is measured according to the GB/T1043.1-2008 standard;
in the processes of the following examples and comparative examples, the extrusion rate of the second extrusion was controlled in the range of 3 to 12 m/s.
Preparation example 1
8kg of styrene is dissolved in 160kg of cyclohexane solvent, 242.8ml of n-butyllithium is added, polymerization reaction is carried out at 50 ℃, the reaction is finished for about 3 hours, 30.04kg of butadiene is added at the rate of 2kg/min, the temperature is kept at 55 ℃ for reaction for 4 hours, and the styrene-butadiene-styrene triblock copolymer with the SBS structure is prepared.
Mixing the triblock copolymer with a catalyst Co/Al (the Co/Al molar ratio is 1: 1.7) according to a mass ratio of 100: 0.2, and carrying out hydrogenation reaction under the condition that the hydrogen pressure is 4.5MPa to prepare the triblock copolymer with the SEBS structure. The triblock copolymer is prepared. The molecular weight of the triblock copolymer is 8 ten thousand, the content of the polystyrene continuous block in the triblock copolymer is 20 weight percent based on the total weight of the triblock copolymer, and the content of the 1, 2-structural unit in the polybutadiene continuous block is 10 weight percent based on the total weight of the polybutadiene continuous block in the triblock copolymer.
Preparation example 2
9.8kg of styrene was dissolved in 200kg of cyclohexane solvent, 301.2ml of n-butyllithium was added, polymerization was carried out at 50 ℃ for about 3 hours, butadiene was added in a total amount of 37.3kg at a rate of 1.7kg/min, and the reaction was carried out at 52 ℃ for 4 hours to obtain styrene-butadiene-styrene triblock copolymer having SBS structure.
Mixing the triblock copolymer with a catalyst Co/Al (the Co/Al molar ratio is 1: 1.7) according to a mass ratio of 100: 0.15, and carrying out hydrogenation reaction under the condition that the hydrogen pressure is 4.7MPa to prepare the triblock copolymer with the SEBS structure. The triblock copolymer is prepared. The molecular weight of the triblock copolymer is 9 ten thousand, the content of the polystyrene chain segment in the triblock copolymer is 25 weight percent based on the total weight of the triblock copolymer, and the content of the 1, 2-structural unit in the polybutadiene chain segment is 8 weight percent based on the total weight of the polybutadiene chain segment in the triblock copolymer.
Preparation example 3
12kg of styrene is dissolved in 250kg of cyclohexane solvent, 369ml of n-butyllithium are added, polymerization is carried out at 50 ℃, the reaction is finished for about 3 hours, butadiene with the total amount of 45.1kg is added at the rate of 2.8kg/min, and the reaction is carried out for 4 hours at the temperature of 55 ℃, thus obtaining the styrene-butadiene-styrene triblock copolymer with SBS structure.
Mixing the triblock copolymer with a catalyst Co/Al (the Co/Al molar ratio is 1: 1.7) according to a mass ratio of 100: 0.25, and carrying out hydrogenation reaction under the condition that the hydrogen pressure is 4.7MPa to prepare the triblock copolymer with the SEBS structure. The triblock copolymer is prepared. The molecular weight of the triblock copolymer is 8.5 ten thousand, and in the triblock copolymer, the content of a polystyrene chain segment is 30 weight percent based on the total weight of the triblock copolymer, and the content of a1, 2-structural unit in a polybutadiene chain segment is 12 weight percent based on the total weight of a polybutadiene chain segment in the triblock copolymer.
Preparation example 4
4kg of styrene was dissolved in 100kg of cyclohexane solvent, 135.6ml of n-butyllithium was added, polymerization was carried out at 50 ℃ for about 3 hours, butadiene was added in a total amount of 16.2kg at a rate of 2.5kg/min, and the reaction was carried out at 55 ℃ for 4 hours, thereby obtaining styrene-butadiene-styrene triblock copolymer having SBS structure.
Mixing the triblock copolymer with a catalyst Co/Al (the Co/Al molar ratio is 1: 1.7) according to a mass ratio of 100: 0.3, and carrying out hydrogenation reaction under the condition that the hydrogen pressure is 4.8MPa to prepare the triblock copolymer with the SEBS structure. The triblock copolymer is prepared. The molecular weight of the triblock copolymer is 5 ten thousand, the content of the polystyrene continuous block in the triblock copolymer is 10 weight percent based on the total weight of the triblock copolymer, and the content of the 1, 2-structural unit in the polybutadiene continuous block is 20 weight percent based on the total weight of the polybutadiene continuous block in the triblock copolymer.
Example 1
Preparing a polyolefin composition according to the following proportions:
a: 100 parts by weight of polyethylene, a copolymer of ethylene and 1-hexene having a melt flow rate of 1.5g/10min and a density of 0.940g/cm3Purchased from Tianjin petrochemical, same below);
b: 60 parts by weight of the styrene-based elastomer obtained in preparation example 1;
c: 150 parts by weight of wood flour;
d: 5 parts by weight of antioxidant 1076 and 5 parts by weight of antioxidant 168.
The Vicat softening point of the above composition was 123 ℃.
(1) And (3) granulation: and (2) feeding the polyolefin composition into a double-screw hopper through a feeding screw, extruding through a double-screw extruder at the extrusion temperature of 200 ℃, and then passing through a granulator to form composition particles.
(2) And (3) blank forming: adding the granulated composition particles into a large-scale plate extruder, and carrying out first extrusion through a die of a mother blank, wherein the heating zone of the die is divided into eight zones, the heating temperature is 220 ℃, the first extrusion temperature is 110 ℃, and the first extrusion speed is 3 m/min; and (3) performing water spraying cooling and first forming on the extruded mother blank by using water at 10 ℃ to form a rough blank with stable dimension.
(3) And (3) stretching and forming: heating the rough blank in an infrared radiation closed heating mode, wherein an infrared heating zone is arranged in seven zones at the temperature of 260 ℃, then heating to the softening point of the polyolefin composition, conveying to an oriented stretching film opening through a crawler belt or a guide roller for second extrusion, heating the stretching film opening in seven zones at the temperature of 138 ℃, obtaining an extruded material, controlling the rate difference between the extrusion rate and the stretching rate of the second extrusion to be 6m/min, stretching the extruded material, then performing water spraying cooling and second forming by using water at the temperature of 10 ℃, and obtaining a tray A1.
Example 2
Preparing a polyolefin composition according to the following proportions:
a: 100 parts by weight of polyethylene, a copolymer of ethylene, 1-butene and 1-hexene having a melt flow rate of 0.8g/10min and a density of 0.930g/cm3)；
B: 40 parts by weight of the styrene-based elastomer obtained in preparation example 2;
c: 120 parts by weight of wood flour;
d: 3 parts by weight of antioxidant 1076 and 2 parts by weight of antioxidant 168.
The Vicat softening point of the above composition was 117 ℃.
(1) And (3) granulation: the polyolefin composition enters a double-screw hopper through a feeding screw, is extruded by a double-screw extruder at the extrusion temperature of 150 ℃, and then passes through a granulator to form composition particles.
(2) And (3) blank forming: adding the granulated composition particles into a large-scale plate extruder, and carrying out first extrusion through a die of a mother blank, wherein the heating zone of the die is divided into eight zones, the heating temperature is 200 ℃, the first extrusion temperature is 125 ℃, and the first extrusion speed is 5 m/min; the extruded green body is cooled and first formed by passing 25 ℃ brine through a cooling roller to form a dimensionally stable green body.
(3) And (3) stretching and forming: heating the rough blank in an oil bath hot roller mode, arranging an infrared heating zone in seven zones at the temperature of 180 ℃, then heating to the softening point of the polyolefin composition, conveying to an oriented stretch film opening through a crawler belt or a guide roller for second extrusion, heating the stretch film opening in seven zones at the temperature of 130 ℃ to obtain an extruded material, controlling the rate difference between the extrusion rate and the stretch rate of the second extrusion to be 3m/min, stretching the extruded material, then performing water spraying cooling and second forming by using water at the temperature of 10 ℃ to obtain a tray A2. The properties of the tray are shown in table 1.
Example 3
Preparing a polyolefin composition according to the following proportions:
a: 100 parts by weight of polyethylene, a copolymer of ethylene and 1-octene having a melt flow rate of 3g/10min and a density of 0.965g/cm3)；
B: 80 parts by weight of the styrenic elastomer obtained in preparation example 3;
c: 180 parts by weight of wood flour;
d: 8 parts by weight of antioxidant 1076 and 5 parts by weight of antioxidant 168.
The vicat softening point of the above composition was 128 ℃.
(1) And (3) granulation: and (2) feeding the polyolefin composition into a double-screw hopper through a feeding screw, extruding the polyolefin composition through a double-screw extruder at the extrusion temperature of 250 ℃, and then passing the polyolefin composition through a granulator to form composition particles.
(2) And (3) blank forming: adding the granulated composition particles into a large-scale plate extruder, and carrying out first extrusion through a die of a mother blank, wherein the heating zone of the die is divided into eight zones, the heating temperature is 250 ℃, the first extrusion temperature is 150 ℃, and the first extrusion speed is 8 m/min; and (3) carrying out water spraying cooling and primary forming on the extruded mother blank by using water at the temperature of-5 ℃ to form a rough blank with stable size.
(3) And (3) stretching and forming: heating the rough blank in an infrared radiation closed heating mode, arranging an infrared heating zone in seven zones at the temperature of 300 ℃, then heating to the softening point of the polyolefin composition, conveying the rough blank to an oriented stretch film opening through a crawler belt or a guide roller for second extrusion, heating the stretch film opening in seven zones at the temperature of 145 ℃ to obtain an extruded material, controlling the rate difference between the extrusion rate and the stretching rate of the second extrusion to be 9m/min, stretching the extruded material, then cooling the extruded material by a cooling roller with 10 ℃ ethylene glycol, and performing second molding to obtain a tray A3. The properties of the tray are shown in table 1.
Example 4
Tray A4 was prepared according to the procedure for example 1, except that the styrenic elastomer from preparation 4 was used as component B. The properties of the tray are shown in table 1.
Example 5
A tray A5 was prepared by following the procedure of example 1 except that in step (3), the extruded material was stretched while controlling the rate difference between the extrusion rate and the stretching rate of the second extrusion to be 1 m/min. The properties of the tray are shown in table 1.
Example 6
A tray A6 was prepared by following the procedure of example 1 except that in step (3), the extruded material was stretched while controlling the rate difference between the extrusion rate and the stretching rate of the second extrusion to be 12 m/min. The properties of the tray are shown in table 1.
Example 7
A tray A7 was prepared by following the procedure of example 1 except that component B was 10 parts by weight of the styrenic elastomer obtained in preparation example 1. The properties of the tray are shown in table 1.
Example 8
The procedure is as in example 1, except that component A is a copolymer of ethylene and 1-hexene, having a melt flow rate of 8g/10min and a density of 0.910g/cm3Thus, a tray A8 was prepared. The properties of the tray are shown in table 1.
Example 9
According to the method of example 1, except that the first extrusion rate in step (2) was 0.5m/min, tray A9 was obtained. The properties of the tray are shown in table 1.
Comparative example 1
Example a tray DA1 was prepared following the procedure of example 1 except that component a was not included in the composition.
Comparative example 2
Example a tray DA2 was prepared following the procedure of example 1 except that component B was not included in the composition.
Comparative example 3
Preparing a polyolefin composition according to the following proportions:
a: 100 parts by weight of polyethylene, a copolymer of ethylene and 1-hexene having a melt flow rate of 1.5g/10min and a density of 0.940g/cm3)；
B: 60 parts by weight of the styrene-based elastomer obtained in preparation example 1;
c: 150 parts by weight of wood flour;
d: 5 parts by weight of antioxidant 1076 and 5 parts by weight of antioxidant 168.
The Vicat softening point of the above composition is 125 ℃.
(1) And (3) granulation: and (2) feeding the polyolefin composition into a double-screw hopper through a feeding screw, extruding through a double-screw extruder at the extrusion temperature of 200 ℃, and then passing through a granulator to form composition particles.
(2) And (3) blank forming: adding the granulated composition particles into a large-scale plate extruder, and carrying out first extrusion through a die of a mother blank, wherein the heating zone of the die is divided into eight zones, the heating temperature is 220 ℃, the first extrusion temperature is 130 ℃, and the first extrusion speed is 5 m/min; and (3) performing water spraying cooling and first forming on the extruded mother blank by using water at 10 ℃ to form a rough blank with stable dimension.
(3) And (3) processing and forming the tray: and (3) carrying out tray machining and forming on the rough blank by a plate machine (purchased from Kun mountain and added with a fine work, and the model is YF1000) to obtain a tray DA 3. The properties of the tray are shown in table 1.
TABLE 1
| Water absorption/(%) | Density (g/cm)3) | Tensile Strength (MPa) | Impact Strength (J/m)2) | |
| A1 | 1.6 | 0.230 | 109 | 460 |
| A2 | 1.3 | 0.485 | 96 | 425 |
| A3 | 1.8 | 0.381 | 102 | 441 |
| A4 | 2.5 | 0.536 | 63 | 267 |
| A5 | 2.8 | 0.864 | 71 | 311 |
| A6 | 3.5 | 0.795 | 76 | 325 |
| A7 | 3.3 | 0.521 | 73 | 321 |
| A8 | 3.5 | 0.635 | 69 | 302 |
| A9 | 3.7 | 0.576 | 70 | 305 |
| DA1 | 3.4 | 0.972 | 20 | 100 |
| DA2 | 3.3 | 0.931 | 82 | 347 |
| DA3 | 2.3 | 1.597 | 90 | 350 |
As can be seen from Table 1, the tray prepared by the method of the present invention has low water absorption, and the tray with low density and lighter weight can be further obtained by controlling the difference between the proper first extrusion and second extrusion tensile rates.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (13)
1. A method of making a tray, the method comprising:
1) sequentially granulating, first extruding and first forming the raw materials to obtain a rough blank;
2) heating the rough blank to the softening point of the raw materials, and then performing second extrusion through an oriented stretch film opening to obtain an extruded material;
3) sequentially stretching and second forming the extruded material;
wherein the difference between the speed of the second extrusion and the speed of the stretching is 1-15 m/min.
2. The process of claim 1, wherein the difference in the rate of the second extrusion and the stretching is 3-9 m/min.
3. The method of claim 1 or 2, wherein the conditions of the first extrusion in step 1) comprise: the extrusion temperature is 110-150 ℃, and the extrusion speed is 0.5-10 m/min.
4. The process according to any one of claims 1 to 3, wherein the raw material is a polyolefin composition comprising polyethylene, a styrenic elastomer and a filler, the styrenic elastomer is a block copolymer of styrene and a conjugated diene, the styrenic elastomer is contained in an amount of 3 to 90 parts by weight and the filler is contained in an amount of 50 to 200 parts by weight, relative to 100 parts by weight of the polyethylene.
5. The method as claimed in claim 4, wherein the styrene-based elastomer is contained in an amount of 40 to 80 parts by weight and the filler is contained in an amount of 120 to 180 parts by weight, relative to 100 parts by weight of the polyethylene.
6. The process according to claim 4 or 5, wherein the conjugated diene is selected from at least one of butadiene, isoprene and myrcene;
preferably, the styrenic elastomer is a triblock copolymer of styrene and butadiene, and the triblock copolymer is an SEBS structure.
7. The method of claim 6, wherein the triblock copolymer is a copolymer prepared by anionic polymerization;
preferably, the molecular weight of the triblock copolymer is from 5 to 15 million, more preferably from 8 to 9 million.
8. The method of claim 7, wherein the triblock copolymer has a polystyrene segment content of 20 to 30 weight percent, based on the total weight of the triblock copolymer;
preferably, the content of 1, 2-structural units in the polybutadiene block is not higher than 15% by weight based on the total weight of the polybutadiene block in the triblock copolymer.
9. The process according to any one of claims 4 to 8, wherein the polyethylene is a homopolymer of ethylene and/or ethylene with C3-8Copolymers of olefins;
preferably, said C3-8The olefin is selected from at least one of propylene, 1-butene, 1-hexene and 1-octene.
10. The process according to any one of claims 4 to 9, wherein the polyethylene has a melt flow rate of (0.5 to 3) g/10min at 230 ℃ under a load of 2.16 kg;
preferably, the polyethylene has a density of (0.930-0.965) g/cm3。
11. The method of any of claims 4-10, wherein the filler is at least one of wood flour, bamboo powder, talc, and calcium carbonate.
12. A tray produced by the method of any one of claims 1 to 11.
13. The tray of claim 12, wherein the density of the tray is 0.2-1.0g/cm3。
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6120863A (en) * | 1996-10-18 | 2000-09-19 | Fort James Corporation | Disposable food contact compatible microwaveable containers having at least one micronodular surface and process for their manufacture |
| CN107955344A (en) * | 2017-12-01 | 2018-04-24 | 山东润德复合材料有限公司 | Micropore lightweight polyester（PET）Plastics Geogrids and its manufacture method |
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2019
- 2019-05-09 CN CN201910386118.5A patent/CN111907083A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6120863A (en) * | 1996-10-18 | 2000-09-19 | Fort James Corporation | Disposable food contact compatible microwaveable containers having at least one micronodular surface and process for their manufacture |
| CN107955344A (en) * | 2017-12-01 | 2018-04-24 | 山东润德复合材料有限公司 | Micropore lightweight polyester（PET）Plastics Geogrids and its manufacture method |
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| Title |
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| 张静峰: "《聚乙烯微孔透气膜的制造原理与性能特点》", 《生活用纸》 * |
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