Two-color light-blocking container and preparation method thereof

Abstract

The present invention relates to the field of food processing technology, and provides a two-color light-blocking container and a preparation method thereof. The two-color light-blocking container comprises: a first light-blocking layer, a second light-blocking layer and a third light-blocking layer; the two-color light-blocking container has an open end and a bottom end opposite to the open end; the first light-blocking layer and the second light-blocking layer both extend from the open end to the middle area of ​​the two-color light-blocking container; the third light-blocking layer extends from the open end to the bottom end, and is sandwiched between the first light-blocking layer and the second light-blocking layer; wherein the first light-blocking layer and the second light-blocking layer present a first color, and the third light-blocking layer presents a second color. The two-color light-blocking container shown in the present invention not only ensures the light-blocking performance of the two-color light-blocking container, but also enables the upper and lower parts of the two-color light-blocking container to present two different appearance colors, thereby ensuring the beauty of its appearance.

Description

Technical Field

[0001] The invention relates to the technical field of food processing, and in particular to a two-color light-blocking container and a preparation method thereof. Background Art

[0002] Polyethylene terephthalate (PET) containers are plastic containers made of PET through injection molding and blow molding. Due to the advantages of PET material such as light weight, strong structure and excellent chemical properties, plastic containers are widely used in beverages, dairy products, edible oils and seasonings.

[0003] For some room temperature light-sensitive beverages, such as dairy products, due to the requirement of long shelf life, plastic containers need to be light-blocking modified to improve their light-blocking performance. The common implementation method is to add white light-blocking modifiers during the injection molding stage of the plastic container, and then use the blow molding process to obtain the light-blocking container. However, in actual applications, it is found that the existing light-blocking containers have a simple structure and a single overall color, which cannot meet the light-blocking performance while ensuring the aesthetic appearance. Summary of the invention

[0004] The present invention provides a two-color light-blocking container and a preparation method thereof, which are used to at least solve or improve the problem that the light-blocking container in the prior art cannot ensure the aesthetic appearance while meeting the light-blocking performance.

[0005] In a first aspect, the present invention provides a two-color light-blocking container, comprising: a first light-blocking layer, a second light-blocking layer, and a third light-blocking layer;

[0006] The two-color light-blocking container has an open end and a bottom end opposite to the open end; the first light-blocking layer and the second light-blocking layer both extend from the open end to the middle area of ​​the two-color light-blocking container; the third light-blocking layer extends from the open end to the bottom end and is sandwiched between the first light-blocking layer and the second light-blocking layer;

[0007] The first light-blocking layer and the second light-blocking layer are in a first color, and the third light-blocking layer is in a second color.

[0008] According to a two-color light-blocking container provided by the present invention, the raw materials selected for at least one of the first light-blocking layer and the second light-blocking layer include a first color masterbatch, a white light-blocking agent and PET particles, and the first color masterbatch presents a first color;

[0009] Alternatively, the raw materials selected for at least one of the first light-blocking layer and the second light-blocking layer include second color masterbatch and PET particles, and the second color masterbatch presents a second color.

[0010] According to a two-color light-blocking container provided by the present invention, the raw materials selected for the third light-blocking layer include white light-blocking agent and PET particles.

[0011] According to a two-color light-blocking container provided by the present invention, the first light-blocking layer and the second light-blocking layer are made of the same material, and the first light-blocking layer and the second light-blocking layer are connected at one end close to the open end, so that the end of the third light-blocking layer close to the open end is wrapped between the first light-blocking layer and the second light-blocking layer;

[0012] And / or, along the extension direction from the open end to the bottom end, the thickness of a portion of the first light-blocking layer and the second light-blocking layer close to the middle region gradually decreases.

[0013] According to the present invention, a two-color light-blocking container is provided, wherein the two-color light-blocking container is formed by stretching and blow molding based on a bottle embryo;

[0014] Along the extension direction from the open end to the bottom end, the bottle embryo includes a embryo mouth section, a transition section, an embryo body section and an embryo bottom section which are connected in sequence; the first light-blocking layer and the second light-blocking layer are extended and arranged along the embryo mouth section and the transition section in sequence.

[0015] According to a two-color light-blocking container provided by the present invention, along the extension direction from the open end to the bottom end, the inner and outer diameters of the transition section gradually decrease, and the thicknesses of the first light-blocking layer and the second light-blocking layer corresponding to the transition section gradually decrease.

[0016] According to a two-color light-blocking container provided by the present invention, the structural morphology of the transition section satisfies the following mathematical relationship:

[0017] (D3-T3) T3 0.8<(D2-T2) T2<(D3-T3) T3;

[0018] Wherein, D2 is the outer diameter of the transition section, D3 is the outer diameter of the embryo body section, T2 is the wall thickness of the transition section, and T3 is the wall thickness of the embryo body section.

[0019] According to a two-color light-blocking container provided by the present invention, the setting position of the transition section in the bottle embryo satisfies the following mathematical relationship:

[0020] 0.3

[0021] Among them, H1 is the height difference between the two ends of the transition section, H2 is the height difference between the two ends of the embryo body section, and H3 is the height difference between the two ends of the embryo bottom section.

[0022] ​In a second aspect, the present invention further provides a method for preparing a two-color light-blocking container, comprising:

[0023] Using a twin-screw injection molding machine, respectively injecting a first light-blocking material and a second light-blocking material into a mold cavity of a preform mold, so as to obtain a preform by injection molding the preform mold;

[0024] The bottle embryo is stretched and blow-molded by a bottle blowing process to prepare the above-mentioned two-color light-blocking container;

[0025] At the initial stage of injection molding, the first light-blocking material flows along the inner and outer walls of the cavity of the preform mold to form the first light-blocking layer and the second light-blocking layer, and the second light-blocking material is located between the first light-blocking layer and the second light-blocking layer to form a first part of the third light-blocking layer;

[0026] At the end of injection molding, the second light-blocking material flows between the inner and outer walls of the cavity to form the second part of the third light-blocking layer.

[0027] According to the method for preparing a two-color light-blocking container provided by the present invention, the step of using a twin-screw injection molding machine to respectively inject a first light-blocking material and a second light-blocking material into the cavity of a preform mold to obtain a preform by injection molding based on the preform mold includes:

[0028] Controlling the first screw to drive the first light-blocking material to flow toward the injection head, and controlling the valve needle in the injection head to be in a first position, so that the first light-blocking material flows through the first flow channel of the injection head to the discharge port of the injection head, and then flows into the mold cavity through the discharge port;

[0029] Control the second screw to drive the second light-blocking material to flow toward the injection molding head, and control the valve needle to be in the second position, so that the second light-blocking material flows to the discharge port through the second flow channel of the injection molding head, and the first light-blocking material flows to the discharge port through the first flow channel and the third flow channel of the injection molding head, ensuring that the first light-blocking material flows along the inner and outer walls of the cavity respectively, and the second light-blocking material flows along the gap between the inner and outer layers of the first light-blocking material;

[0030] Controlling the first screw to reduce the feeding amount of the first light-blocking material, controlling the second screw to increase the feeding amount of the second light-blocking material, until the second light-blocking material flows along the gap between the inner and outer walls of the cavity, and then controlling the second light-blocking material to fill the cavity;

[0031] The preform mold is subjected to pressure-maintaining, cooling and demoulding treatments in sequence to obtain the preform.

[0032] According to the method for preparing a two-color light-blocking container provided by the present invention, during the process of pressurizing and cooling the preform mold, the method further comprises:

[0033] The first screw is controlled to drive the first light-blocking material to flow toward the injection head, and the valve needle in the injection head is controlled to be in a first position, so that the first light-blocking material flows through the first flow channel to the discharge port of the injection head, and then flows through the discharge port to the injection port of the cavity.

[0034] According to the method for preparing a two-color light-blocking container provided by the present invention, the method further comprises the step of configuring the first light-blocking material as follows:

[0035] The white light-blocking agent and the first color masterbatch are configured in a ratio of (2:11) to (4:9) to obtain a compound material; the compound material and the PET particles are configured in a ratio of 13:87 to obtain the first light-blocking material;

[0036] Alternatively, the second color masterbatch and the PET particles are configured in a ratio of (9:11) to (89:91) to obtain the first light-blocking material.

[0037] According to the method for preparing a two-color light-blocking container provided by the present invention, the method further comprises the step of configuring the second light-blocking material as follows:

[0038] The white light-blocking agent and PET particles are mixed in a ratio of 8:92 to obtain the second light-blocking material.

[0039] The present invention provides a two-color light-blocking container and a preparation method thereof. The two-color light-blocking container is provided with a first light-blocking layer, a second light-blocking layer and a third light-blocking layer. The third light-blocking layer is extended from the open end to the bottom end of the two-color light-blocking container, and the third light-blocking layer is sandwiched between the first light-blocking layer and the second light-blocking layer in the portion from the open end to the middle area of ​​the two-color light-blocking container. Then, the upper portion of the two-color light-blocking container forms a three-layer light-blocking structure, and the lower portion of the two-color light-blocking container forms a single-layer light-blocking structure. This design not only ensures the light-blocking performance of the two-color light-blocking container, but also enables the upper and lower portions of the two-color light-blocking container to present two different appearance colors, thereby ensuring the beauty of its appearance. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0041] Figure 1 It is a schematic cross-sectional structure diagram of the double-color light-blocking container provided by the present invention.

[0042] Figure 2 The figure is a schematic diagram of the three-dimensional structure of the preform of the two-color light-blocking container provided by the present invention.

[0043] Figure 3 The figure is a schematic cross-sectional structural diagram of a bottle embryo of a two-color light-blocking container provided by the present invention.

[0044] Figure 4 It is a schematic flow chart of the method for preparing the two-color light-blocking container provided by the present invention.

[0045] Figure 5 The present invention provides a schematic flow diagram of using a twin-screw injection molding machine to respectively inject a first light-blocking material and a second light-blocking material into a mold cavity of a preform mold to obtain a preform by injection molding the preform mold.

[0046] Figure 6 This is one of the structural schematic diagrams of the injection molding head and the preform mold provided by the present invention cooperating to prepare a preform.

[0047] Figure 7 This is the second structural schematic diagram of the injection molding head and the preform mold provided by the present invention cooperating to prepare a preform.

[0048] Figure 8 This is the third structural schematic diagram of the injection molding head and the preform mold provided by the present invention cooperating to prepare a preform.

[0049] Fig. 9 This is the fourth structural schematic diagram of the injection molding head and the preform mold provided by the present invention cooperating to prepare a preform.

[0050] Fig.10 This is the fifth structural schematic diagram of the injection molding head and the preform mold provided by the present invention cooperating to prepare a preform.

[0051] Fig.11 The graph is a graph of transmittance of the upper, middle and lower regions of the two-color light-blocking container prepared by the first solution provided by the present invention relative to the wavelength of light.

[0052] Fig.12 It is a schematic diagram of the distribution of the number of infrared lamps turned on when the bottle embryo prepared by the first solution is blown into a bottle provided by the present invention.

[0053] Fig.13 This is a curve diagram of the transmittance of the upper, middle and lower regions of the two-color light-blocking container prepared by the second solution provided by the present invention relative to the wavelength of light.

[0054] Fig.14It is a schematic diagram of the distribution of the number of infrared lamps turned on when the bottle embryo prepared by the second solution is blown into a bottle provided by the present invention.

[0055] Reference numerals:

[0056] 1. Two-color light-blocking container; 101. open end; 102. bottom end; 11. first light-blocking layer; 12. second light-blocking layer; 13. third light-blocking layer;

[0057] 2. Bottle embryo; 21. Embryo mouth segment; 22. Transition segment; 23. Embryo body segment; 24. Embryo bottom segment;

[0058] 3. Bottle embryo mold; 301, cavity;

[0059] 4. Injection head; 41. Valve needle; 400. Discharge port; 401. First flow channel; 402. Second flow channel; 403. Third flow channel;

[0060] 100. A first light-blocking material; 200. A second light-blocking material. DETAILED DESCRIPTION

[0061] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0062] Combine the following Figure 1-Figure 14 , the two-color light-blocking container and the preparation method thereof provided by the embodiment of the invention are described in detail through specific embodiments and their application scenarios.

[0063] In the first aspect, Figure 1 As shown, an embodiment of the present invention provides a two-color light-blocking container 1, comprising: a first light-blocking layer 11, a second light-blocking layer 12 and a third light-blocking layer 13;

[0064] The two-color light-blocking container 1 has an open end 101 and a bottom end 102 opposite to the open end 101; the first light-blocking layer 11 and the second light-blocking layer 12 both extend from the open end 101 to the middle area of ​​the two-color light-blocking container 1; the third light-blocking layer 13 extends from the open end 101 to the bottom end 102, and is sandwiched between the first light-blocking layer 11 and the second light-blocking layer 12;

[0065] The first light-blocking layer 11 and the second light-blocking layer 12 are in a first color, and the third light-blocking layer 13 is in a second color.

[0066] It is understandable that the two-color light-blocking container 1 may be a light-blocking plastic container, and the two-color light-blocking container 1 may be configured in a cup shape, a bottle shape, a barrel shape, etc., and no specific limitation is made to this.

[0067] The light blocking rate of the two-color light-blocking container 1 at 550nm in the visible light range reaches more than 99.9%, and the light blocking rate of the overall structure of the two-color light-blocking container 1 in the visible light range is not less than 99.5%.

[0068] Optionally, the two-color light-blocking container 1 is a bottle-shaped container, and a bottle mouth is formed at the portion of the two-color light-blocking container 1 near the open end 101, and an external thread or a clamping structure is provided on the peripheral wall of the bottle mouth so that the two-color light-blocking container 1 can be detachably connected to the bottle cap through the bottle mouth.

[0069] The raw materials of the first light-blocking layer 11, the second light-blocking layer 12 and the third light-blocking layer 13 corresponding to the two-color light-blocking container 1 can be a mixture of color masterbatches and PET particles, and the color masterbatches are selectively configured for display colors according to actual needs.

[0070] The first light-blocking layer 11 and the second light-blocking layer 12 are relatively arranged on the inner and outer sides of the third light-blocking layer 13. Since the first light-blocking layer 11 and the second light-blocking layer 12 are in the first color and the third light-blocking layer 13 is in the second color, the upper part of the two-color light-blocking container 1 is in the first color and the lower part of the two-color light-blocking container 1 is in the second color, thereby ensuring the aesthetic beauty of the overall shape of the two-color light-blocking container 1.

[0071] In practical applications, the first color and the second color represent different color types, and the first color and the second color can be configured according to actual needs. For example, the first color can be yellow or green, and the second color can be white; of course, the first color can be yellow, and the second color can be green, or the first color can be green, and the second color can be yellow, etc., which will not be listed here one by one.

[0072] The two-color light-blocking container 1 shown in the embodiment of the present invention is provided with a first light-blocking layer 11, a second light-blocking layer 12 and a third light-blocking layer 13. The third light-blocking layer 13 is extended from the open end 101 to the bottom end 102 of the two-color light-blocking container 1, and the third light-blocking layer 13 is sandwiched between the first light-blocking layer 11 and the second light-blocking layer 12 in the portion from the open end 101 to the middle area of ​​the two-color light-blocking container 1. Then, the upper part of the two-color light-blocking container 1 forms a three-layer light-blocking structure, and the lower part of the two-color light-blocking container 1 forms a single-layer light-blocking structure. This design not only ensures the light-blocking performance of the two-color light-blocking container 1, but also makes the upper and lower parts of the two-color light-blocking container 1 present two different appearance colors, thereby ensuring the beauty of its appearance.

[0073] In some embodiments, raw materials selected for at least one of the first light-blocking layer 11 and the second light-blocking layer 12 include a first color masterbatch, a white light-blocking agent, and PET particles, and the first color masterbatch presents a first color.

[0074] Specifically, the first light-blocking layer 11 and the second light-blocking layer 12 are made of the same material, and the raw materials thereof both include a first color masterbatch, a white light-blocking agent, and PET particles.

[0075] Exemplarily, the first color masterbatch has light-blocking properties and can be a yellow masterbatch. The yellow masterbatch can be made from polyethylene terephthalate as a base material, compounded with a yellow solvent, titanium dioxide, an antioxidant and a diffusant, and then plasticized and granulated.

[0076] Illustratively, the production process of PET particles includes polymerization and pelletizing. During the polymerization process, terephthalic acid (TPA) and ethylene glycol (EG) are subjected to esterification and polycondensation reactions under high temperature and high pressure conditions to generate PET. During the pelletizing process, the polymerized PET melt is cut into small particles by a pelletizer to obtain PET particles. PET particles are usually cylindrical or spherical, which are convenient for transportation and use.

[0077] In practical applications, according to the light blocking requirements, the first color masterbatch and the white light blocking agent can be mixed in a first ratio to obtain a compound material, and then the compound material and PET particles can be mixed in a second ratio to obtain a raw material for plasticizing and molding the first light blocking layer 11 and the second light blocking layer 12.

[0078] In some embodiments, the raw materials selected for at least one of the first light-blocking layer 11 and the second light-blocking layer 12 include a second color masterbatch and PET particles, and the second color masterbatch presents a second color.

[0079] Specifically, the first light-blocking layer 11 and the second light-blocking layer 12 are made of the same material, and the raw materials thereof both include second color masterbatch and PET particles.

[0080] Exemplarily, the second color masterbatch has light-blocking properties and can be a green masterbatch. The green masterbatch can be made from polyethylene terephthalate as a base material, compounded with a green solvent, titanium dioxide, an antioxidant and a diffusant, and then plasticized and granulated.

[0081] In practical applications, the second color masterbatch and the PET particles can be mixed in a third ratio according to light blocking requirements to obtain a raw material for plasticizing and molding the first light blocking layer 11 and the second light blocking layer 12 .

[0082] In some embodiments, the materials used for the third light-blocking layer 13 include white light-blocking agent and PET particles.

[0083] Specifically, the white light-blocking agent can be made by using polyethylene terephthalate as a base material, compounding titanium dioxide (which may also be talcum powder or barium sulfate), an antioxidant and a diffusing agent, and then undergoing plasticization and granulation.

[0084] In practical applications, according to light blocking requirements, the white light blocking agent and the PET particles may be mixed in a fourth ratio to obtain a raw material for plasticizing and molding the third light blocking layer 13 .

[0085] In some embodiments, Figure 1 and Figure 3 As shown, the first light-blocking layer 11 and the second light-blocking layer 12 are made of the same material, and the ends of the first light-blocking layer 11 and the second light-blocking layer 12 close to the open end 101 are connected so that the end of the third light-blocking layer 13 close to the open end 101 is wrapped between the first light-blocking layer 11 and the second light-blocking layer 12.

[0086] It is understandable that the two-color light-blocking container 1 is stretched and blow-molded based on the bottle embryo 2. By configuring the first light-blocking layer 11 and the second light-blocking layer 12 to be of the same material, the first light-blocking material and the second light-blocking material can be injected into the cavity 301 of the bottle embryo mold 3 in succession during the injection molding stage of the bottle embryo 2, ensuring that the first light-blocking material flows along the inner and outer walls of the cavity 301 to form the first light-blocking layer 11 and the second light-blocking layer 12, and the second light-blocking material flows along the gap between the first light-blocking layer 11 and the second light-blocking layer 12 to form the third light-blocking layer 13. This design can ensure that the end of the third light-blocking layer 13 close to the open end 101 is wrapped between the first light-blocking layer 11 and the second light-blocking layer 12, and ensure the injection molding efficiency of the bottle embryo 2.

[0087] In some embodiments, along the extension direction from the open end 101 to the bottom end 102 , the thickness of a portion of the first light blocking layer 11 and the second light blocking layer 12 close to the middle region gradually decreases.

[0088] It is understandable that the middle area of ​​the two-color light-blocking container 1 is located in the bottle body of the two-color light-blocking container 1, and the wall thickness of the bottle body of the two-color light-blocking container 1 is kept consistent along the extension direction from the open end 101 to the bottom end 102. In this way, along the extension direction from the open end 101 to the bottom end 102, the thickness of the first light-blocking layer 11 and the second light-blocking layer 12 near the middle area gradually decreases, and the thickness of the third light-blocking layer 13 in the corresponding area gradually increases until the thickness of the third light-blocking layer 13 is consistent with the wall thickness of the bottle body. This design ensures that the first light-blocking layer 11, the second light-blocking layer 12 and the third light-blocking layer 13 are tightly combined together at a position near the middle area of ​​the two-color light-blocking container 1, and ensures the aesthetic appearance of the two-color light-blocking container 1.

[0089] like Figure 2 and Figure 3As shown, the two-color light-blocking container 1 is stretched and blow-molded based on the bottle embryo 2; along the extension direction from the open end 101 to the bottom end 102, the bottle embryo 2 includes a embryo mouth section 21, a transition section 22, a embryo body section 23 and an embryo bottom section 24 connected in sequence; the first light-blocking layer 11 and the second light-blocking layer 12 are extended and arranged along the embryo mouth section 21 and the transition section 22 in sequence.

[0090] It can be understood that, since the two-color light-blocking container 1 is stretched and blow-molded based on the bottle embryo 2, the bottle embryo 2 has a composite layer structure corresponding to the two-color light-blocking container 1, that is, the bottle embryo 2 has an open end 101 and a bottom end 102 opposite to the open end 101, and the bottle embryo 2 includes the first light-blocking layer 11, the second light-blocking layer 12 and the third light-blocking layer 13 shown in the above embodiment, the first light-blocking layer 11 and the second light-blocking layer 12 are extended along the embryo mouth section 21 and the transition section 22 in sequence, and the third light-blocking layer 13 is extended along the embryo mouth section 21, the transition section 22, the embryo body section 23 and the embryo bottom section 24 in sequence, and is sandwiched between the first light-blocking layer 11 and the second light-blocking layer 12.

[0091] like Figure 2 and Figure 3 As shown, for the bottle embryo 2, the wall thickness of the bottle embryo 2 can gradually increase or decrease along the extension direction from the open end 101 to the bottom end 102, while the outer diameters of the embryo mouth section 21, the transition section 22 and the embryo body section 23 gradually decrease.

[0092] The average wall thickness of the embryo mouth section 21 is 0.35 mm to 0.43 mm, the average wall thickness of the transition section 22 is 0.39 mm to 0.42 mm, and the average wall thickness of the embryo body section 23 is 0.33 mm to 0.42 mm.

[0093] Furthermore, in order to ensure the composite effect of the first light-blocking layer 11, the second light-blocking layer 12 and the third light-blocking layer 13 and reduce the influence of the material difference on the blowing of the two-color light-blocking container 1, the inner and outer diameters of the transition section 22 are gradually reduced along the extension direction from the open end 101 to the bottom end 102, and the thickness of the first light-blocking layer 11 and the second light-blocking layer 12 corresponding to the transition section 22 is gradually reduced.

[0094] Furthermore, if Figure 3 As shown, due to the different wall thicknesses of the transition section 22 and the embryo body section 23, and the differences in heat absorption and thermal conductivity of different materials, during the heating process of the preform 2, in order to ensure the controllable temperature distribution and stretching uniformity of the transition section 22 and the embryo body section 23, weaken the narrow blowing window caused by the difference in wall thickness and material properties, and achieve the widening of the heating and blowing process window of the preform 2, the structural form of the transition section 22 in the embodiment of the present invention satisfies the following mathematical relationship:

[0095] (D3-T3) T3 0.8<(D2-T2) T2<(D3-T3) T3;

[0096] Wherein, D2 is the outer diameter of the transition section 22 , D3 is the outer diameter of the embryo body section 23 , T2 is the wall thickness of the transition section 22 , and T3 is the wall thickness of the embryo body section 23 .

[0097] like Figure 3 As shown, the outer diameter D1 of the embryo mouth section 21, the outer diameter D2 of the transition section 22 and the outer diameter D3 of the embryo body section 23 decrease in sequence.

[0098] It should be noted that along the extension direction from the open end 101 to the bottom end 102 , the transition section 22 is configured to extend along an arc-shaped trajectory and to be closed. The wall thickness T3 of the transition section 22 is the wall thickness along the normal direction of the outer surface of the transition section 22 .

[0099] At the same time, the embodiment of the present invention also sets the transition section 22 in the preform 2 to satisfy the following mathematical relationship:

[0100] 0.3

[0101] Among them, H1 is the height difference between the two ends of the transition section 22 , H2 is the height difference between the two ends of the embryo body section 23 , and H3 is the height difference between the two ends of the embryo bottom section 24 .

[0102] Based on the above settings, the embodiment of the present invention limits the shape and related dimensions of the preform 2, which can widen the blowing process window of the preform 2 in the blowing stage, ensure the smoothness of the shape and thickness changes at various positions of the preform 2, and reduce the impact of differences in heat absorption, heat conduction, stretching and other characteristics caused by different light-blocking materials and their distribution on the blowing window.

[0103] In the second aspect, Figure 4 As shown, the embodiment of the present invention also provides a method for preparing a two-color light-blocking container 1, comprising the following steps:

[0104] Step 410, using a twin-screw injection molding machine to respectively inject a first light-blocking material and a second light-blocking material into a mold cavity of a preform mold, so as to obtain a preform by injection molding the preform mold;

[0105] Step 420, stretching and blow-molding the bottle embryo by a bottle blowing process to prepare a two-color light-blocking container; wherein, in the initial stage of injection molding, the first light-blocking material flows along the inner and outer walls of the cavity to form a first light-blocking layer and a second light-blocking layer, and the second light-blocking material is located between the first light-blocking layer and the second light-blocking layer to form a first part of a third light-blocking layer; in the later stage of injection molding, the first light-blocking material is controlled to stop being injected into the cavity, and the second light-blocking material flows between the inner and outer walls of the cavity to form a second part of the third light-blocking layer. ​

[0106] It is understandable that if Figures 6 to 9 As shown, the preform mold 3 has a cavity 301 corresponding to the structure of the preform 2, the bottom end 102 of the cavity 301 is used to form the open end 101 of the preform 2, and the top end of the cavity 301 is used to form the bottom end 102 of the preform 2; the preform mold 3 is provided with an injection port, which is connected to the top end of the cavity 301.

[0107] In actual application, the discharge port 400 of the injection head 4 of the twin-screw injection molding machine is connected to the injection port, and the twin-screw injection molding machine is used to inject the heated and plasticized first light-blocking material and the second light-blocking material into the cavity 301 through the injection head 4 respectively. By controlling the injection timing of the first light-blocking material and the second light-blocking material, the second light-blocking material can be controlled to be wrapped between the inner and outer layers of the first light-blocking material at the initial stage of injection molding, and flow to the lower half of the cavity 301 together with the first light-blocking material, so as to injection-mold the embryo mouth section 21 and the transition section 22 of the bottle embryo 2, and in the later stage of injection molding, the second light-blocking material is controlled to flow between the inner and outer walls of the cavity 301 to the upper half of the cavity 301 alone, and fill the cavity 301, so as to injection-mold the embryo body section 23 and the embryo bottom section 24 of the bottle embryo 2.

[0108] like Figure 5 As shown, the embodiment of the present invention uses a twin-screw injection molding machine to respectively inject a first light-blocking material and a second light-blocking material into the cavity of a preform mold, so as to obtain a preform by injection molding the preform mold, including the following steps:

[0109] Step 510, controlling the first screw to drive the first light-blocking material to flow toward the injection molding head, and controlling the valve needle in the injection molding head to be in the first position, so that the first light-blocking material flows through the first flow channel of the injection molding head to the discharge port of the injection molding head, and then flows into the mold cavity through the discharge port;

[0110] Step 520, controlling the second screw to drive the second light-blocking material to flow toward the injection molding head, and controlling the valve needle to be in the second position, so that the second light-blocking material flows to the discharge port through the second flow channel of the injection molding head, and the first light-blocking material flows to the discharge port through the first flow channel and the third flow channel of the injection molding head, ensuring that the first light-blocking material flows along the inner and outer walls of the cavity respectively, and the second light-blocking material flows along the gap between the inner and outer layers of the first light-blocking material;

[0111] Step 530, controlling the first screw to reduce the feeding amount of the first light-blocking material, and controlling the second screw to increase the feeding amount of the second light-blocking material, until the second light-blocking material flows along the gap between the inner and outer walls of the cavity, and then controlling the second light-blocking material to fill the cavity;

[0112] Step 540 , the preform mold is subjected to pressure holding, cooling and demoulding treatments in sequence to obtain the preform.

[0113] It can be understood that the twin-screw injection molding machine has a first feeding channel and a second feeding channel, the first screw is rotatably disposed in the first feeding channel, the second screw is rotatably disposed in the second feeding channel, the first feeding channel is respectively connected to the first flow channel 401 and the third flow channel 403 of the injection head 4, and the second feeding channel is connected to the second flow channel 402 of the injection head 4.

[0114] At the same time, the surrounding walls of the first feeding channel and the second feeding channel are provided with heating devices to ensure that the first light blocking material 100 in the first feeding channel can be in a molten and plasticized state, and to ensure that the second light blocking material 200 in the second feeding channel can be in a molten and plasticized state.

[0115] The feeding or retraction of the first light-blocking material 100 can be controlled by controlling the forward and reverse rotation of the first screw; correspondingly, the feeding or retraction of the second light-blocking material 200 can be controlled by controlling the forward and reverse rotation of the second screw.

[0116] like Figures 6 to 9 As shown, for the injection head 4, the valve needle 41 extends toward the discharge port 400 of the injection head 4 and is inserted into the third flow channel 403. The first flow channel 401 and the second flow channel 402 are both extended along the circumference of the third flow channel 403, and the second flow channel 402 is located between the first flow channel 401 and the third flow channel 403.

[0117] At the same time, by controlling the position of the end of the valve needle 41 relative to the discharge port 400, the conduction state of the first flow channel 401, the second flow channel 402 and the third flow channel 403 relative to the discharge port 400 can be controlled;

[0118] like Figure 6 and Fig. 9 As shown, when the valve needle 41 is in the first position, the end of the valve needle 41 extends into the first flow channel 401, the first flow channel 401 and the discharge port 400 are connected, and the communication paths between the second flow channel 402 and the third flow channel 403 relative to the discharge port 400 are blocked.

[0119] like Figure 7 As shown, when the valve needle 41 is in the second position, the end of the valve needle 41 extends into the third flow channel 403, and the first flow channel 401, the second flow channel 402 and the third flow channel 403 are respectively connected to the discharge port 400.

[0120] like Figure 8 As shown, when the valve needle 41 is in the third position, the end of the valve needle 41 extends into the second flow channel 402, the first flow channel 401 and the second flow channel 402 are respectively connected to the discharge port 400, and the communication path of the third flow channel 403 relative to the discharge port 400 is blocked.

[0121] like Fig.10As shown, when the valve needle 41 is in the fourth position, the end of the valve needle 41 is inserted into the discharge port 400 of the injection head 4 to block the discharge port 400, and the injection head 4 stops discharging materials.

[0122] under Figures 6 to 10 , the injection molding process of the bottle embryo 2 shown in the embodiment of the present invention is described in detail.

[0123] like Figure 6 As shown, when initially injecting material into the cavity 301 of the preform mold 3, the first screw is controlled to rotate forward, and the valve needle 41 in the injection head 4 is set to the first position. Driven by the first screw, the plasticized first light-blocking material 100 in the first feeding channel flows to the first flow channel 401, and then flows out from the discharge port 400 of the injection head 4 through the first flow channel 401, and then enters the cavity 301.

[0124] like Figure 7 As shown, while controlling the first screw to rotate forward, controlling the second screw to rotate forward, and setting the valve needle 41 in the injection head 4 to the second position, at this time, the first light-blocking material 100 in the first feeding channel in a plasticized state passes through the first flow channel 401 and the third flow channel 403 to reach the discharge port 400, and the second light-blocking material 200 in the second feeding channel in a plasticized state passes through the second flow channel 402 to reach the discharge port 400, according to the first flow channel 401, the second flow channel 402 and the third flow channel 403 relative to the discharge port 400. 0, can ensure that when the first light-blocking material 100 and the second light-blocking material 200 enter the cavity 301, the first light-blocking material 100 flows along the inner and outer walls of the cavity 301 respectively, and the second light-blocking material 200 is wrapped between the inner and outer layers of the first light-blocking material 100 and flows along the gap between the inner and outer layers of the first light-blocking material 100. The first light-blocking material 100 and the second light-blocking material 200 will reach the lower half of the cavity 301 according to this arrangement under the action of gravity to form the embryo mouth section 21 of the bottle embryo 2.

[0125] like Figure 8 As shown, the speed of the first screw rotating in the forward direction is controlled to be reduced (the feeding speed of the first screw is reduced), the speed of the second screw rotating in the forward direction is increased (the feeding speed of the second screw is increased), and the valve needle 41 in the injection head 4 is set to the third position, so that in the direction from bottom to top along the cavity 301, the thicknesses of the first light-blocking layer 11 and the second light-blocking layer 12 are gradually reduced, and the thickness of the third light-blocking layer 13 is gradually increased, so as to form the transition section 22 of the preform 2.

[0126] Next, the first screw is controlled to rotate in the reverse direction to absorb the first light-blocking material 100 by the reverse rotation of the first screw, and the second screw is controlled to keep rotating in the forward direction so that the second light-blocking material 200 fills the mold cavity 301, thereby forming the embryo body section 23 and the embryo bottom section 24 of the bottle embryo 2.

[0127] like Fig. 9 As shown, during the process of pressure-maintaining and cooling the preform mold 3, the first screw is controlled to rotate forward, and the first screw drives the first light-blocking material 100 to flow toward the injection head 4, and the valve needle 41 in the injection head 4 is set at the first position, so that the first light-blocking material 100 flows to the discharge port 400 of the injection head 4 through the first flow channel 401, and then flows to the injection port of the cavity 301 through the discharge port 400, so that the blank in the cavity 301 is pressure-maintained and shrinkage-compensated by the first light-blocking material 100, so as to form a colorful cold material well at the bottom end 102 of the preform 2.

[0128] like Fig.10 As shown, after the first light-blocking material 100 is injected into the injection port, the first screw and the second screw both stop rotating, and the valve needle 41 is set to the fourth position to block the injection head 4, so that the injection head 4 stops discharging the material. At this time, after the preform mold 3 is cooled, the preform 2 can be demoulded, and the colored area of ​​the bottom end 102 of the preform 2 can be cut off to ensure that the bottom end 102 of the preform 2 is consistent in color with the lower body of the preform 2.

[0129] Based on the above process, the preparation of one preform can be completed. When preparing the next preform, it is only necessary to repeat the above process to enter the next production cycle.

[0130] Furthermore, when the bottle preform is stretched and blow-molded by the bottle blowing process, the bottle preform is heated by an infrared lamp. After the temperature of the bottle preform rises to the temperature required by the bottle blowing process, the bottle preform is stretched and blow-molded.

[0131] like Fig.12 and Fig.14 As shown, the heating process of the preform is carried out in a heating chamber, the heating chamber has a mounting wall extending along a "U"-shaped path, 1 to 10 groups of infrared lamp tubes are sequentially arranged along the extending direction of the mounting wall, the number of infrared lamp tubes in each group of infrared lamp tubes is set to 9, and the 9 infrared lamp tubes are sequentially arranged from bottom to top along the vertical direction.

[0132] At the same time, a conveyor line is also provided in the heating room. The conveyor line is extended along the extension direction of the installation wall. The conveyor line supports the bottle preforms with the open mouth facing downward to control the bottle preforms to pass through 1 to 10 groups of infrared lamps in sequence; among them, the preform mouth section, transition section, preform body section and preform bottom section of the bottle preform correspond to the four infrared lamps arranged from bottom to top in each group respectively.

[0133] In some embodiments, the preparation method of the present invention further includes the following steps of configuring a first light-blocking material:

[0134] The white light-blocking agent and the first color masterbatch are configured in a ratio of (2:11) to (4:9) to obtain a compound material; the compound material and the PET particles are configured in a ratio of 13:87 to obtain a first light-blocking material.

[0135] It is understandable that by configuring the white light-blocking agent and the first color masterbatch in proportion to form a compound material, it can be ensured that the compound material contains 20%-70% of conventional white light-blocking agent. This technical route for preparing the first light-blocking material based on the compound material, when the compound material and PET particles are configured in proportion to obtain the first light-blocking material to participate in the preparation of the two-color light-blocking container 1, can ensure that the upper and lower parts of the bottle preform 2 have nearly consistent fluidity, thermal conductivity and controllable tensile properties during the injection molding and blow molding process of the bottle preform 2, thereby improving the molding quality of the bottle preform 2. This design also ensures high application flexibility in commercial applications, and can be flexibly configured according to actual needs during production and processing.

[0136] For the compound material, the ratio of the white light-blocking agent to the first color masterbatch can be specifically set to 2:11, 3:10 or 4:9; wherein, the ratio of the white light-blocking agent to the first color masterbatch and the ratio of the compound material to the PET particles are both based on mass ratio, and the total mass is measured as 100.

[0137] In some embodiments, the preparation method of the present invention further includes the following steps of configuring a first light-blocking material:

[0138] The second color masterbatch and the PET particles are configured in a ratio of (9:11) to (89:91) to obtain a first light-blocking material.

[0139] It is understandable that the present invention can adopt color masterbatch and titanium dioxide light-blocking masterbatch technology to develop light-blocking masterbatch with a single color. For example, the second color masterbatch is a green masterbatch. For applications with large usage and a single and stable formula, the technical path of configuring the first light-blocking material described in the present invention has the advantage of being convenient for terminal production and use.

[0140] For the first light-blocking material shown in the embodiment of the present invention, the ratio of the second color masterbatch and the PET particles can be specifically 9:91, 10:90 or 11:89; wherein the ratio of the second color masterbatch and the PET particles is a mass ratio, and the total mass is measured as 100.

[0141] In some embodiments, the preparation method of the present invention further includes the following steps of configuring a first light-blocking material:

[0142] The second color masterbatch and the PET particles are configured in a ratio of (9:11) to (89:91) to obtain a first light-blocking material.

[0143] It is understandable that the present invention can adopt color masterbatch and titanium dioxide light-blocking masterbatch technology to develop light-blocking masterbatch with a single color. For example, the second color masterbatch is a green masterbatch. For applications with large usage and a single and stable formula, the technical path of configuring the first light-blocking material described in the present invention has the advantage of being convenient for terminal production and use.

[0144] For the first light-blocking material shown in the embodiment of the present invention, the ratio of the second color masterbatch and the PET particles can be specifically 9:91, 10:90 or 11:89; wherein, the ratio of the second color masterbatch and the PET particles is a mass ratio, and the total mass is calculated as 100.

[0145] The following describes the method for preparing the dual-color light-blocking container of the present invention through various specific embodiments according to the first configuration scheme of the first light-blocking material.

[0146] Example 1

[0147] (1) The yellow masterbatch and the white light-blocking agent are uniformly mixed in a ratio of 9:4 to prepare a compound material; the compound material and the PET particles are mixed in a ratio of 13:87, and dried to obtain a first light-blocking material; the first light-blocking material is added to the first feeding channel for melting and plasticization, and the first screw is fed to control the feeding;

[0148] (2) Drying the white light-blocking agent and the PET particles separately, and then mixing them in a ratio of 8:92 to obtain a second light-blocking material; adding the second light-blocking material to the second feeding channel for melting and plasticization, and waiting for the second screw to perform feeding control;

[0149] (3) According to the operation flow of steps 510 to 540, a preform is obtained by injection molding based on the preform mold, and the preform is subjected to pressure holding, cooling and demolding. The preform is blown to obtain a two-color light-blocking container, and the average wall thicknesses of the preform mouth section, transition section and body section of the two-color light-blocking container are 0.38 mm, 0.40 mm and 0.40 mm respectively;

[0150] (4) Test the transmittance of the two-color light-blocking container and obtain the following Fig.11 The transmittance curve of the upper, middle and lower regions of the two-color light-blocking container relative to the wavelength of light is shown; Fig.11It can be seen that the light blocking rate of the two-color light-blocking container at 550nm in the visible light range reaches more than 99.9%, that is, the transmittance of the upper, middle and lower areas of the two-color light-blocking container is less than 0.1%; the overall structure of the two-color light-blocking container has a light blocking rate greater than 99.5% in the entire visible light range (roughly between 400nm-700nm), which can meet the shelf life requirements of long-term dairy products at room temperature.

[0151] In the process of heating the preform with infrared lamps, Fig.12 The medium grey squares indicate that the infrared lamps are on, and the white squares indicate that the infrared lamps are not on. Since the yellow compound material and the currently used white light blocking agent have certain differences in infrared heat absorption, heat conduction and stretching properties; the above scheme can overcome the above disadvantages and have continuous and stable production conditions through continuous bottle blowing test evaluation, meeting the production window requirements of preform injection molding and blow molding; since the preform mouth section and transition section are colored, it is conducive to strengthening the infrared heating absorption effect (conventional white light blocking agents have stronger reflection effect), so the number and power of the No. 1 and No. 2 infrared lamps arranged in the vertical direction in this area are significantly lower, which is conducive to energy saving and consumption reduction in the bottle blowing process.

[0152] Example 2

[0153] (1) The yellow masterbatch and the white light-blocking agent are uniformly mixed in a ratio of 10:3 to prepare a compound material; the compound material and the PET particles are mixed in a ratio of 13:87, and dried to obtain a first light-blocking material; the first light-blocking material is added to the first feeding channel for melting and plasticization, and the first screw is fed to control the feeding;

[0154] (2) Drying the white light-blocking agent and the PET particles separately, and then mixing them in a ratio of 8:92 to obtain a second light-blocking material; adding the second light-blocking material to the second feeding channel for melting and plasticization, and waiting for the second screw to perform feeding control;

[0155] (3) According to the operation flow of steps 510 to 540, a preform is obtained by injection molding based on the preform mold, and the preform is subjected to pressure holding, cooling and demolding. The preform is blown to obtain a two-color light-blocking container, and the average wall thicknesses of the preform mouth section, transition section and body section of the two-color light-blocking container are 0.41 mm, 0.39 mm and 0.37 mm respectively;

[0156] (4) The transmittance of the two-color light-blocking container was tested, and the result showed that the light-blocking rate of the two-color light-blocking container was over 99.7% at 550nm in the visible light range. The light-blocking rate of the overall structure of the two-color light-blocking container was greater than 99.5% in the entire visible light range (roughly between 400nm and 700nm), which can meet the shelf life requirements of long-term dairy products at room temperature.

[0157] Example 3

[0158] (1) The yellow masterbatch and the white light-blocking agent are uniformly mixed in a ratio of 11:2 to prepare a compound material; the compound material and the PET particles are mixed in a ratio of 13:87, and dried to obtain a first light-blocking material; the first light-blocking material is added to the first feeding channel for melting and plasticization, and the first screw is fed to control the feeding;

[0159] (2) Drying the white light-blocking agent and the PET particles separately, and then mixing them in a ratio of 8:92 to obtain a second light-blocking material; adding the second light-blocking material to the second feeding channel for melting and plasticization, and waiting for the second screw to perform feeding control;

[0160] (3) According to the operation flow of steps 510 to 540, a preform is obtained by injection molding based on the preform mold, and the preform is subjected to pressure holding, cooling and demolding. The preform is blown to obtain a two-color light-blocking container, and the average wall thicknesses of the preform mouth section, transition section and body section of the two-color light-blocking container are 0.44 mm, 0.41 mm and 0.33 mm respectively;

[0161] (4) The transmittance of the two-color light-blocking container was tested, and the result showed that the light-blocking rate of the two-color light-blocking container was over 99.8% at 550nm in the visible light range. The light-blocking rate of the overall structure of the two-color light-blocking container was greater than 99.5% in the entire visible light range (roughly between 400nm and 700nm), which can meet the shelf life requirements of long-term dairy products at room temperature.

[0162] Comparative Example 1

[0163] (1) The yellow masterbatch and the white light-blocking agent are uniformly mixed in a ratio of 12:1 to prepare a compound material; the compound material and the PET particles are mixed in a ratio of 13:87, and dried to obtain a first light-blocking material; the first light-blocking material is added to the first feeding channel for melting and plasticization, and the first screw is fed to control the feeding;

[0164] (2) Drying the white light-blocking agent and the PET particles separately, and then mixing them in a ratio of 8:92 to obtain a second light-blocking material; adding the second light-blocking material to the second feeding channel for melting and plasticization, and waiting for the second screw to perform feeding control;

[0165] (3) According to the operation flow of steps 510 to 540, a preform is obtained by injection molding based on the preform mold, and the preform is subjected to pressure holding, cooling and demolding. The preform is blown to obtain a two-color light-blocking container, and the average wall thicknesses of the preform mouth section, transition section and body section of the two-color light-blocking container are 0.44 mm, 0.40 mm and 0.33 mm respectively;

[0166] (4) The transmittance of the two-color light-blocking container was tested, and the results showed that the light-blocking rate of the two-color light-blocking container was over 99.5% at 550nm in the visible light range. The light-blocking rate of the overall structure of the two-color light-blocking container was greater than 98.3% in the entire visible light range (roughly between 400nm and 700nm), which could not meet the shelf life requirements of long-term dairy products at room temperature.

[0167] Comparative Example 2

[0168] (1) The yellow masterbatch is not compounded, but is directly mixed with PET particles in a ratio of 13:87, and dried to obtain a first light-blocking material; the first light-blocking material is added to the first feeding channel for melting and plasticization, and then the first screw is used for feeding control;

[0169] (2) Drying the white light-blocking agent and the PET particles separately, and then mixing them in a ratio of 8:92 to obtain a second light-blocking material; adding the second light-blocking material to the second feeding channel for melting and plasticization, and waiting for the second screw to perform feeding control;

[0170] (3) According to the operation flow of steps 510 to 540 above, a preform is obtained by injection molding based on a preform mold, and the preform is subjected to pressure holding, cooling and demolding. When the preform is blown, it is found that the titanium dioxide ratios in the upper and lower parts of the preform are too different, which leads to overheating of the preform mouth section and transition section of the preform during the blowing process. If conventional blowing parameters are used, the structure of this part of the area after blowing is likely to be too thin; if pre-blowing parameters are used, this part of the structure is likely to be too thick, not formed or eccentric, and the blowing window is too narrow, which does not meet the conditions for continuous and stable production.

[0171] The following describes the method for preparing the dual-color light-blocking container of the present invention through various specific embodiments according to the second configuration scheme of the first light-blocking material.

[0172] Example 4

[0173] (1) mixing green masterbatch and PET particles in a ratio of 11:89 and performing drying to obtain a first light-blocking material; adding the first light-blocking material into a first feeding channel for melting and plasticization, and waiting for the first screw to perform feeding control;

[0174] (2) Drying the white light-blocking agent and the PET particles separately, and then mixing them in a ratio of 8:92 to obtain a second light-blocking material; adding the second light-blocking material to the second feeding channel for melting and plasticization, and waiting for the second screw to perform feeding control;

[0175] (3) According to the operation flow of steps 510 to 540, a preform is obtained by injection molding based on the preform mold, and the preform is subjected to pressure holding, cooling and demolding. The preform is blown to obtain a two-color light-blocking container, and the average wall thicknesses of the preform mouth section, transition section and body section of the two-color light-blocking container are 0.38 mm, 0.40 mm and 0.40 mm respectively;

[0176] (4) Test the transmittance of the two-color light-blocking container and obtain the following Fig.13 The transmittance curve of the upper, middle and lower regions of the two-color light-blocking container relative to the wavelength of light is shown; Fig.13 It can be seen that the light blocking rate of the two-color light-blocking container at 550nm in the visible light range reaches more than 99.9%, that is, the transmittance of the upper, middle and lower areas of the two-color light-blocking container is less than 0.1%; the overall structure of the two-color light-blocking container has a light blocking rate greater than 99.5% in the entire visible light range (roughly between 400nm-700nm), which can meet the shelf life requirements of long-term dairy products at room temperature.

[0177] In the process of heating the preform with infrared lamps, Fig.14 The medium grey squares indicate that the infrared lamps are on, and the white squares indicate that the infrared lamps are not on. Since the green light-blocking material and the currently used white light-blocking agent have certain differences in infrared heat absorption, heat conduction and stretching properties, the above scheme can overcome the above disadvantages and have continuous and stable production conditions through continuous bottle blowing test evaluation, meeting the production window requirements for preform injection molding and blow molding; since the preform mouth section and transition section are colored, it is beneficial to enhance the infrared heating absorption effect (conventional white light-blocking agents have stronger reflection effects), so the number and power of the No. 1 and No. 2 infrared lamps arranged vertically in this area are significantly lower, which is beneficial to energy saving and consumption reduction in the bottle blowing process.

[0178] Example 5

[0179] (1) Green masterbatch and PET particles are mixed in a ratio of 10:90 and dried to obtain a first light-blocking material; the first light-blocking material is added to a first feeding channel for melting and plasticization, and then the first screw is used for feeding control;

[0180] (2) Drying the white light-blocking agent and the PET particles separately, and then mixing them in a ratio of 8:92 to obtain a second light-blocking material; adding the second light-blocking material to the second feeding channel for melting and plasticization, and waiting for the second screw to perform feeding control;

[0181] (3) According to the operation flow of steps 510 to 540, a preform is obtained by injection molding based on the preform mold, and the preform is subjected to pressure holding, cooling and demolding. The preform is blown to obtain a two-color light-blocking container, and the average wall thicknesses of the preform mouth section, transition section and body section of the two-color light-blocking container are 0.40 mm, 0.42 mm and 0.39 mm respectively;

[0182] (4) The transmittance of the two-color light-blocking container was tested, and the result showed that the light-blocking rate of the two-color light-blocking container was above 99.8% at 550nm in the visible light range. The light-blocking rate of the overall structure of the two-color light-blocking container was greater than 99.5% in the entire visible light range (roughly between 400nm and 700nm), which can meet the shelf life requirements of long-term dairy products at room temperature.

[0183] Example 6

[0184] (1) mixing green masterbatch and PET particles in a ratio of 9:91 and drying to obtain a first light-blocking material; adding the first light-blocking material into a first feeding channel for melting and plasticization, waiting for the first screw to perform feeding control;

[0185] (2) Drying the white light-blocking agent and the PET particles separately, and then mixing them in a ratio of 8:92 to obtain a second light-blocking material; adding the second light-blocking material to the second feeding channel for melting and plasticization, and waiting for the second screw to perform feeding control;

[0186] (3) According to the operation flow of steps 510 to 540, a preform is obtained by injection molding based on the preform mold, and the preform is subjected to pressure holding, cooling and demolding. The preform is blown to obtain a two-color light-blocking container, and the average wall thicknesses of the two-color light-blocking container corresponding to the preform mouth section, transition section and preform body section are 0.43 mm, 0.40 mm and 0.37 mm respectively;

[0187] (4) The transmittance of the two-color light-blocking container was tested, and the result showed that the light-blocking rate of the two-color light-blocking container was above 99.5% at 550nm in the visible light range. The light-blocking rate of the overall structure of the two-color light-blocking container was greater than 99.5% in the entire visible light range (roughly between 400nm and 700nm), which can meet the shelf life requirements of long-term dairy products at room temperature.

[0188] Comparative Example 3

[0189] (1) Green masterbatch and PET particles are mixed in a ratio of 8:92, and dried to obtain a first light-blocking material; the first light-blocking material is added to a first feeding channel for melting and plasticization, and then the first screw is used for feeding control;

[0190] (2) Drying the white light-blocking agent and the PET particles separately, and then mixing them in a ratio of 8:92 to obtain a second light-blocking material; adding the second light-blocking material to the second feeding channel for melting and plasticization, and waiting for the second screw to perform feeding control;

[0191] (3) According to the operation flow of steps 510 to 540, a preform is obtained by injection molding based on the preform mold, and the preform is subjected to pressure holding, cooling and demolding. The preform is blown to obtain a two-color light-blocking container, and the average wall thicknesses of the preform mouth section, transition section and body section of the two-color light-blocking container are 0.45 mm, 0.41 mm and 0.35 mm respectively;

[0192] (4) The transmittance of the two-color light-blocking container was tested, and it was found that the light-blocking rate of the overall structure of the two-color light-blocking container was greater than 97% in the entire visible light range (roughly between 400nm-700nm), which cannot meet the shelf life requirements of long-term dairy products at room temperature.

[0193] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a two-color light-blocking container, characterized in that: include: Using a twin-screw injection molding machine, respectively injecting a first light-blocking material and a second light-blocking material into a mold cavity of a preform mold, so as to obtain a preform by injection molding the preform mold; The bottle embryo is stretched and blow-molded by a bottle blowing process to prepare a two-color light-blocking container, wherein the two-color light-blocking container comprises a first light-blocking layer, a second light-blocking layer and a third light-blocking layer; the two-color light-blocking container has an open end and a bottom end opposite to the open end; the first light-blocking layer and the second light-blocking layer both extend from the open end to the middle area of ​​the two-color light-blocking container; the third light-blocking layer extends from the open end to the bottom end and is sandwiched between the first light-blocking layer and the second light-blocking layer; the first light-blocking layer and the second light-blocking layer present a first color, and the third light-blocking layer presents a second color; Wherein, at the initial stage of injection molding, the first light-blocking material flows along the inner and outer walls of the cavity to form the first light-blocking layer and the second light-blocking layer, and the second light-blocking material is located between the first light-blocking layer and the second light-blocking layer to form the first part of the third light-blocking layer; At the end of injection molding, the second light-blocking material flows between the inner and outer walls of the cavity to form the second part of the third light-blocking layer.

2. The method for preparing a two-color light-blocking container according to claim 1, characterized in that: The step of using a twin-screw injection molding machine to respectively inject the first light-blocking material and the second light-blocking material into the cavity of the preform mold to obtain the preform by injection molding the preform mold includes: Controlling the first screw to drive the first light-blocking material to flow toward the injection head, and controlling the valve needle in the injection head to be in a first position, so that the first light-blocking material flows through the first flow channel of the injection head to the discharge port of the injection head, and then flows into the mold cavity through the discharge port; Control the second screw to drive the second light-blocking material to flow toward the injection molding head, and control the valve needle to be in the second position, so that the second light-blocking material flows to the discharge port through the second flow channel of the injection molding head, and the first light-blocking material flows to the discharge port through the first flow channel and the third flow channel of the injection molding head, ensuring that the first light-blocking material flows along the inner and outer walls of the cavity respectively, and the second light-blocking material flows along the gap between the inner and outer layers of the first light-blocking material; Controlling the first screw to reduce the feeding amount of the first light-blocking material, controlling the second screw to increase the feeding amount of the second light-blocking material, until the second light-blocking material flows along the gap between the inner and outer walls of the cavity, and then controlling the second light-blocking material to fill the cavity; The preform mold is subjected to pressure-maintaining, cooling and demoulding treatments in sequence to obtain the preform.

3. The method for preparing a two-color light-blocking container according to claim 2, characterized in that: During the process of maintaining pressure and cooling the preform mold, the preparation method further comprises: The first screw is controlled to drive the first light-blocking material to flow toward the injection head, and the valve needle in the injection head is controlled to be in a first position, so that the first light-blocking material flows through the first flow channel to the discharge port of the injection head, and then flows through the discharge port to the injection port of the cavity.

4. The method for preparing a two-color light-blocking container according to claim 1, characterized in that: The preparation method further comprises the step of configuring the first light-blocking material as follows: The white light-blocking agent and the first color masterbatch are configured in a ratio of (2:11) to (4:9) to obtain a compound material; the compound material and the PET particles are configured in a ratio of 13:87 to obtain the first light-blocking material; Alternatively, the second color masterbatch and the PET particles are configured in a ratio of (9:11) to (89:91) to obtain the first light-blocking material.

5. The method for preparing a two-color light-blocking container according to claim 1, characterized in that: The preparation method further comprises the step of configuring the second light-blocking material as follows: The white light-blocking agent and PET particles are mixed in a ratio of 8:92 to obtain the second light-blocking material.

6. The method for preparing a two-color light-blocking container according to claim 1, characterized in that: The raw materials selected for at least one of the first light-blocking layer and the second light-blocking layer include a first color masterbatch, a white light-blocking agent and PET particles, and the first color masterbatch presents a first color; Alternatively, the raw materials selected for at least one of the first light-blocking layer and the second light-blocking layer include second color masterbatch and PET particles, and the second color masterbatch presents a second color.

7. The method for preparing a two-color light-blocking container according to claim 1, characterized in that: The raw materials selected for the third light-blocking layer include white light-blocking agent and PET particles.

8. The method for preparing a two-color light-blocking container according to claim 1, characterized in that: The first light-blocking layer and the second light-blocking layer are made of the same material, and one end of the first light-blocking layer and one end of the second light-blocking layer close to the open end are connected, so that one end of the third light-blocking layer close to the open end is wrapped between the first light-blocking layer and the second light-blocking layer; And / or, along the extension direction from the open end to the bottom end, the thickness of a portion of the first light-blocking layer and the second light-blocking layer close to the middle region gradually decreases.

9. The method for preparing a two-color light-blocking container according to any one of claims 1 to 8, characterized in that: The two-color light-blocking container is formed by stretching and blow molding based on the bottle embryo; Along the extension direction from the open end to the bottom end, the bottle embryo includes a embryo mouth section, a transition section, an embryo body section and an embryo bottom section which are connected in sequence; the first light-blocking layer and the second light-blocking layer are extended and arranged along the embryo mouth section and the transition section in sequence.

10. The method for preparing a two-color light-blocking container according to claim 9, characterized in that: Along the extension direction from the open end to the bottom end, the inner and outer diameters of the transition section gradually decrease, and the thicknesses of the first light-blocking layer and the second light-blocking layer corresponding to the transition section gradually decrease.

11. The method for preparing a two-color light-blocking container according to claim 10, characterized in that: The structural morphology of the transition section satisfies the following mathematical relationship: <h2 style=";text-align:left;direction:ltr">(D3-T3)<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr"> T3<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr"> 0.8<(D2-T2)<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr"> T2 (D3-T3)<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr"> T3; Wherein, D2 is the outer diameter of the transition section, D3 is the outer diameter of the embryo body section, T2 is the wall thickness of the transition section, and T3 is the wall thickness of the embryo body section.

12. The method for preparing a two-color light-blocking container according to claim 10, characterized in that: The setting position of the transition section in the preform satisfies the following mathematical relationship: 0.3<H1 / (H2+H3)<0.8; Among them, H1 is the height difference between the two ends of the transition section, H2 is the height difference between the two ends of the embryo body section, and H3 is the height difference between the two ends of the embryo bottom section.

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