Gold sand film and preparation method thereof

Abstract

The invention belongs to the technical field of gold sand films, and particularly relates to a gold sand film and a preparation method thereof.The gold sand film is prepared from, by mass, 10-15 parts of LDPE, the density of the LDPE ranges from 0.910 g / cm < 3 > to 0.915 g / cm < 3 >; 10 to 20 parts of LLDPE, wherein the density of the LLDPE is 0.915 to 0.920 g / cm < 3 >; 15 to 25 parts of HDPE, wherein the density of the HDPE is 0.945 to 0.960 g / cm < 3 >; 10 to 15 parts of MLDPE, wherein the density of the MLDPE is 0.920 to 0.930 g / cm < 3 >; 15 to 35 parts of POE, wherein the density of the POE is 0.870 to 0.900 g / cm < 3 >; and 4-6 parts of a TiO2 auxiliary agent. The gold sand film is formed at a time, by improving the film formula and the gold sand point lines, the gram weight of the film is reduced while certain strength and toughness of the film are maintained, and the obvious gold sand effect is achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of gold sand film and specifically relates to a gold sand film and a preparation method thereof. BACKGROUND

[0002] The gold sand film is a product with different surface pattern from the conventional cast film, and the macroscopic surface presents a starry light reflection effect under the light, having a high-end visual effect.

[0003] The gold sand film is generally applied to the outer packaging of products, and the production process is cast film forming, and then the formed film is subjected to one or more times of embossing, wherein the multiple embossing can make the film have a better gold sand effect. However, the mechanical force generated by the embossing roller in the embossing process can cause certain damage to the film, and due to the performance of the film itself, the gold sand film is prone to risks such as rupture and pattern collapse in the multiple embossing process, so the lower limit of the grammage of the gold sand film in the traditional process is usually 35 g / m 2 Therefore, the gold sand film needs to increase the thickness of the film to ensure the processing feasibility of multiple embossing.

[0004] However, although the thicker film layer can improve the strength of the gold sand film, it can also cause poor toughness and brittleness of the gold sand film, which is not suitable for small packaging fields such as sanitary napkin products, and the material cost of the gold sand film is also restricted. In addition, the process of multiple embossing also leads to a complicated production process of the gold sand film, increasing the equipment investment and production cost. SUMMARY

[0005] In order to solve the problems existing in the prior art, the application provides a gold sand film and a preparation method thereof. The gold sand film is one-time formed, the formula of the film and the gold sand pattern are improved, the grammage of the film is reduced while maintaining a certain strength and toughness of the film, and the gold sand effect is obvious.

[0006] The specific technical scheme adopted by the application is as follows:

[0007] A gold sand film, the formula of the gold sand film comprises, by mass fraction:

[0008] 10-15 parts of LDPE, the density of the LDPE is 0.910-0.915 g / cm 3 ;

[0009] 10-20 parts of LLDPE, the density of the LLDPE is 0.915-0.920 g / cm 3 ;

[0010] 15-25 parts of HDPE, the density of the HDPE is 0.945-0.960 g / cm 3 ;

[0011] 10-15 parts of MLDPE, the density of MLDPE being 0.920-0.930 g / cm 3 ;

[0012] 15-35 parts of POE, the density of POE being 0.870-0.900 g / cm 3 ;

[0013] 4-6 parts of TiO2 additive.

[0014] Further, the melt index of the LDPE is 0.3-1.5 g / 10 min;

[0015] the melt index of the LLDPE being 2-3 g / 10 min;

[0016] the melt index of the HDPE being 2.5-3.5 g / 10 min;

[0017] the melt index of the MLDPE being 0.5-2 g / 10 min;

[0018] the melt index of the POE being 2-10 g / 10 min.

[0019] Further, the branched structure of the POE is C6 and C8 alternately present, and the molecular weight distribution of the MLDPE is 2-2.5.

[0020] Further, the preparation method comprises the following steps:

[0021] According to the formula of the golden sand film, the LDPE, LLDPE, HDPE, MLDPE, POE and TiO2 additive are blended into the extruder according to the blending ratio, the mixed material is extruded through the die head of the extruder and is cooled and shaped, the film curtain in the molten state is extruded to form the protruding golden sand points by means of the shaping lines of the surface of the embossed counter roller, and the golden sand film is obtained.

[0022] Further, the screw temperature of the extruder is 150-300 ℃, the temperature of the die head is 270-300 ℃, the temperature of the cooling and shaping is 30-40 ℃, the rubber roller pressure is 5-7 MPa, and the auxiliary machine running line speed is 25-30 m / min.

[0023] Further, the grammage of the golden sand film is 18-25 g / m 2 .

[0024] Further, the embossed counter roller comprises a pattern roller and a rubber roller, the surface of the pattern roller is provided with a plurality of groups of concave shaping grooves, the plurality of groups of the shaping grooves are arranged at intervals and jointly form the shaping lines of the embossed counter roller, and the surface of the rubber roller is smooth.

[0025] Further, the straight lines where the adjacent edges of the shaping grooves are located intersect.

[0026] Further, the shaping groove is in a triangular pyramid structure, a tip of the triangular pyramid structure is formed as a groove bottom side of the shaping groove, a bottom of the triangular pyramid structure is formed as an opening side of the shaping groove, and a depth of the shaping groove is 80-100 mu m.

[0027] Further, the number of the shaping grooves per 1.6 mm diameter circular area of the shaping line is 225-400.

[0028] The beneficial effects of the present application are:

[0029] 1. In the present application, the gold sand film is one-time formed, by improving the film formula and the gold sand point line, the strength and toughness of the film are maintained, the grammage of the film is reduced, and the gold sand effect is obvious, which can be applied to small packaging.

[0030] 2. In the present application, LDPE, LLDPE, HDPE, MLDPE and POE are compounded, the crystallinity difference of each component is utilized, and the elastomer properties of POE are combined, so that the gold sand film has high strength and flexibility while being thinned.

[0031] POE can cooperate with MLDPE to make the material intertangle in a molten state, the soft and rigid sections of the tangled material form a cross state, the flexible section of POE can reduce the stress concentration caused by the gold sand point pyramid structure to the film and improve the elongation rate of the material, and the rigid section of POE can improve the rigidity of the product and improve the strength index.

[0032] 3. The gold sand point line in the present application is randomly distributed, compared with the regular arrangement of gold sand points (the straight lines where the adjacent sides are located are parallel to each other), the directions of the edges of the randomly distributed gold sand points are inconsistent, and the reflection angles of the gold sand points are different, which avoids the reflection dead angle caused by the regular arrangement, and the gold sand effect can be presented under different observation angles, which is beneficial to improving the uniformity of the gold sand visual effect.

[0033] In addition, the regularly distributed gold sand point line can cause the film surface to have a concave line similar to a crack, when the gold sand film is stressed, the concave line is more prone to stress concentration, and a tear is formed along the concave line, and the randomly distributed gold sand points can make the crack path tortuous, thereby improving the tear resistance of the gold sand film. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 It is an enlarged schematic view of the gold sand point arrangement mode of Example 1.

[0035] Figure 2 It is an enlarged schematic view of the gold sand point arrangement mode of Example 2.

[0036] Figure 3An enlarged schematic view of the gold-sand dot arrangement of Example 3;

[0037] Figure 4 An enlarged schematic view of the gold-sand dot arrangement of Example 4;

[0038] Figure 5 An enlarged schematic view of the gold-sand dot arrangement of Example 5;

[0039] Figure 6 An enlarged schematic view of the pattern roller. DETAILED DESCRIPTION

[0040] The present application is further described below in conjunction with the accompanying drawings and specific embodiments:

[0041] The present application provides a gold-sand film, the formula of the gold-sand film comprises, by mass fraction:

[0042] 10-15 parts of LDPE, the density of the LDPE is 0.910-0.915 g / cm 3 ;

[0043] 10-20 parts of LLDPE, the density of the LLDPE is 0.915-0.920 g / cm 3 ;

[0044] 15-25 parts of HDPE, the density of the HDPE is 0.945-0.960 g / cm 3 ;

[0045] 10-15 parts of MLDPE, the density of the MLDPE is 0.920-0.930 g / cm 3 ;

[0046] 15-35 parts of POE, the density of the POE is 0.870-0.900 g / cm 3 ;

[0047] 4-6 parts of TiO2 additives.

[0048] The production process of traditional gold-sand film is multiple embossing, so that the film presents better gold-sand effect, but the mechanical force generated by the embossing roller in the embossing process can cause certain damage to the film, and due to the performance of the film itself, the gold-sand film is prone to risks such as rupture and pattern collapse in the multiple embossing process, therefore, the lower limit of the grammage of the gold-sand film in the traditional process is usually 35 g / m 2 Therefore, the gold-sand film needs to increase the film thickness to ensure the processing feasibility of multiple embossing.

[0049] However, although the thicker film layer can improve the strength of the golden sand film, it can also cause the golden sand film to be poor in toughness and brittle, which is not suitable for small packaging fields such as sanitary napkin products, and the material cost of the golden sand film is also restricted. In addition, the process of multiple embossing also causes the production process of the golden sand film to be complicated, and increases the equipment investment and production cost.

[0050] Therefore, in the present application, a one-time embossing forming process is adopted and the film layer thickness is reduced. In order to ensure that the golden sand film does not break and other risks during the embossing process, the film ratio of the golden sand film is improved in the present application.

[0051] In the present application, LDPE, LLDPE, HDPE, MLDPE and POE are compounded, the crystallinity difference of each component is utilized, and the elastomer characteristics of POE are combined, so that the golden sand film has high strength and flexibility while being thinned.

[0052] The low-density polyethylene LDPE has a short branched chain structure, low intermolecular crystallinity, provides initial flexibility and transparency of the film, and reduces the rigidity of the overall film; the long branched chain structure of the linear low-density polyethylene LLDPE endows the film with impact strength and puncture resistance, and when blended with LDPE, the flexibility chain segment winding effect is improved, the tensile recovery ability of the base film is improved, and the pattern is prevented from being broken due to excessive deformation during embossing;

[0053] The high crystallinity of the high-density polyethylene HDPE provides rigid support, ensures that the film has sufficient tensile strength under low grammage;

[0054] The medium-density polyethylene MLDPE has flexibility and rigidity, and acts as a "bridge phase" in the blended system to promote the compatibility between different density polyethylenes and reduce interface defects;

[0055] POE can cooperate with MLDPE to make the materials intertangle in a molten state, and the soft and rigid segments of the tangled materials form a state of mutual intersection, the flexible segment of POE can reduce the stress concentration caused by the conical structure of the golden sand point on the film, and improve the elongation rate of the material; the rigid segment of POE can improve the rigidity of the product and improve the strength index.

[0056] The melt index of the LDPE is 0.3-1.5 g / 10 min;

[0057] The melt index of the LLDPE is 2-3 g / 10 min;

[0058] The melt index of the HDPE is 2.5-3.5 g / 10 min;

[0059] The melt index of the MLDPE is 0.5-2 g / 10 min;

[0060] The melt index of the POE is 2-10 g / 10 min.

[0061] The branched structure of the POE is C6 and C8 alternately present, and the molecular weight distribution of the MLDPE is 2-2.5.

[0062] The C6 (hexene) and C8 (octene) alternate branched structure of the POE forms long and short chain interwoven flexible spring-like physical crosslinking points, and when the film is subjected to embossing pressure, the elastic branched chain can absorb energy and reduce stress concentration, thereby ensuring that the gold sand film can withstand embossing mechanical force without breaking at a low grammage.

[0063] A preparation method of a gold sand film, the preparation method comprising the following steps:

[0064] According to the formula of the gold sand film, LDPE, LLDPE, HDPE, MLDPE, POE and TiO2 additives are blended into the extruder according to the blending ratio, the mixed material is extruded through the die head of the extruder and cooled and shaped, and the molten film curtain is extruded to form protruding gold sand points by means of the shaped lines of the embossing counter roller surface, thereby obtaining the gold sand film.

[0065] The screw temperature of the extruder is 150-300 DEG C, the temperature of the die head is 270-300 DEG C, the temperature of the cooling and shaping is 30-40 DEG C, the melt pressure is 5-7 MPa, and the line speed is 25-30 m / min.

[0066] In the present application, the process parameters in the preparation process of the gold sand film are limited, wherein the melt viscosity temperature of the die head temperature is higher than 250 DEG C, so that the blended melt is extruded in a laminar flow state, and the thickness unevenness caused by turbulent flow is reduced.

[0067] The shaping temperature of 30-40 DEG C can make the material form a mixed structure of a small amount of large-size crystals and a large amount of small-size crystals, wherein the large-size crystals provide rigidity, and the small-size crystals provide toughness, thereby ensuring the structural stability of the film during embossing, and avoiding the problem of brittleness of the film.

[0068] Further, the grammage of the gold sand film is 18-25 g / m2. In the present application, the lower limit of the grammage of the traditional gold sand film is broken through by virtue of the improvement of the material blending ratio and the preparation process, and the grammage of the gold sand film is 25 g / m 2 Therefore, the production material cost is reduced.

[0069] The embossing counter roller comprises a pattern roller and a rubber roller, the surface of the pattern roller is provided with a plurality of groups of concave shaping grooves, the plurality of groups of shaping grooves are arranged at intervals and jointly form the shaping lines of the embossing counter roller, and the surface of the rubber roller is smooth

[0070] The straight lines where the adjacent edges of the shaping grooves are located intersect.

[0071] The gold sand dots in the present invention are randomly distributed. Compared with the regular arrangement of gold sand dots (the straight lines where adjacent edges are located are parallel to each other), the directions of the edges of the randomly distributed gold sand dots are inconsistent, and the reflection angles of the gold sand dots are also different, avoiding the reflection blind spots caused by the regular arrangement. The gold sand effect can be presented at different observation angles, which is conducive to improving the uniformity of the gold sand visual effect.

[0072] In addition, the regularly distributed gold sand spots will cause crack-like depressions to appear on the surface of the film. When the gold sand film is subjected to stress, the stress is more easily concentrated at the depressions, causing tears to form along the depressions. The randomly distributed gold sand spots can make the crack path tortuous, thereby improving the tear resistance of the gold sand film.

[0073] like Figure 6 As shown, Figure 6 It is an enlarged view of the pattern roller, and the diameter of the viewing area is 1.6mm. The shaping groove is a triangular pyramid structure, the tip of the triangular pyramid structure forms the bottom side of the groove of the shaping groove, the bottom of the triangular pyramid structure forms the opening side of the shaping groove, and the depth of the shaping groove is 80-100μm. The triangular pyramid structure has three inclined side surfaces, and when light is incident, it will form multi-angle reflections on the three cone surfaces. Compared with plane or cylindrical protrusions, each side of the triangular pyramid is an independent reflective unit, which can decompose a single light source into multiple beams of scattered light, making the macroscopic surface present a dense flashing effect. At the same time, the bottom surface of the triangular pyramid is a triangle, which is a geometrically stable structure. The protrusions formed after embossing are not easy to collapse due to external force.

[0074] Furthermore, the number of shaping grooves on each circular area with a diameter of 1.6 mm is 225-400. By reducing the density of gold sand points and increasing the area of ​​non-gold sand point areas, although the gold sand effect is reduced to a certain extent, the elongation of the gold sand film is greatly improved.

[0075] The roots of the triangular pyramidal protrusions of high-density gold sand points are too close to each other, resulting in the superposition of stress concentration areas at the roots of adjacent protrusions during stretching, forming early cracks; while the lower density increases the distance between the protrusions, forming a stress-free buffer zone between the stress concentration areas. This area can absorb tensile energy through elastic deformation, thereby delaying crack propagation. Specific embodiment:

[0077] Example 1

[0078] According to the formula of the gold sand film, LDPE, LLDPE, HDPE, MLDPE, POE and TiO2 additives are mixed in proportion and added to the extruder. The mixture is extruded through the die head of the extruder and cooled to shape. The molten film curtain is squeezed by the shaping lines on the surface of the embossed roller to form raised gold sand points to obtain the gold sand film.

[0079] The surface of the embossing roller is provided with regularly arranged triangular pyramid shaped grooves, and the lines of the adjacent sides of the grooves are parallel to each other.

[0080] The arrangement of the gold sand points is shown in Figure 1 .

[0081] Example 2

[0082] The difference between Example 2 and Example 1 is that the surface of the embossing roller in Example 2 is provided with randomly arranged triangular pyramid shaped grooves, and the lines of the adjacent sides of the grooves intersect each other.

[0083] The arrangement of the gold sand points is shown in Figure 2 .

[0084] Example 3

[0085] The difference between Example 3 and Example 2 is that the height and the protruding angle of the gold sand points are reduced in Example 3.

[0086] The arrangement of the gold sand points is shown in Figure 3 .

[0087] Example 4

[0088] The difference between Example 4 and Example 3 is that the density of the gold sand points is reduced and the area of the non-gold sand point region is increased in Example 4.

[0089] The arrangement of the gold sand points is shown in Figure 4 .

[0090] Example 5

[0091] The difference between Example 5 and Example 4 is that the density of the gold sand points is further reduced and the area of the non-gold sand point region is further increased in Example 5.

[0092] The arrangement of the gold sand points is shown in Figure 5 .

[0093] Examples 6-11

[0094] The difference between Examples 6-11 and Example 5 is that the process parameters and the film material ratio are different.

[0095] The specific process parameters and the film material ratio of Examples 1-11 are shown in Table 1 and Table 2.

[0096] Table 1

[0097]

[0098]

[0099] Table 2

[0100] Ratio (parts) LDPE LLDPE HDPE MLDPE POE TiO2adjuvant Example 1 12 35 20 12 - 5 Example 2 12 35 20 12 - 5 Example 3 12 35 20 12 - 5 Example 4 12 35 20 12 - 5 Example 5 12 35 20 12 - 5 Example 6 12 35 20 12 - 5 Example 7 12 35 20 12 - 5 Example 8 12 35 20 12 - 5 Example 9 12 15 20 12 20 5 Example 10 12 15 20 12 20 5 Example 11 12 15 20 12 20 5

[0101] The gold sand film prepared in Examples 1-11 was subjected to performance detection, and the detection results are shown in Table 3.

[0102] Table 3

[0103]

[0104] The difference between Examples 1-5 is only in the arrangement of the gold sand points and the different parameters such as the density, the protruding angle of the gold sand points.

[0105] As can be seen from Table 3, the strength and elongation of the gold sand film prepared in Example 5 are improved compared with the gold sand films prepared in Examples 1-4. It can be found by comparing Example 5 with Examples 1-4 that the random arrangement of the gold sand points, the reduction of the protruding angle and height of the gold sand points, and the reduction of the protruding density of the gold sand points can improve the strength and toughness of the gold sand film.

[0106] Examples 6-11 all use the gold sand lines of Example 5, and the strength and toughness of the gold sand film prepared in Example 10 are optimal.

Claims

1. A gold sand film, characterized by, The formula of the golden sand film comprises, by mass fraction: 10-15 parts of LDPE having a density of 0.910-0.915 g / cm 3 ; 10-20 parts of LLDPE, density of LLDPE 0.915-0.920 g / cm 3 ; 15-25 parts HDPE, density of HDPE 0.945-0.960 g / cm 3 ; 10-15 parts MLDPE, density of MLDPE 0.920-0.930 g / cm 3 ; 15-35 parts POE, density of POE 0.870-0.900 g / cm 3 ; 4-6 parts of TiO2 additives.

2. The gold sand film according to claim 1, wherein The melt index of the LDPE is 0.3-1.5 g / 10 min; The melt index of the LLDPE is 2-3 g / 10 min; The melt index of the HDPE is 2.5-3.5 g / 10 min; The melt index of the MLDPE is 0.5-2 g / 10 min; The melt index of the POE is 2-10 g / 10 min.

3. The gold sand film according to claim 1, wherein The branched structure of the POE is C6 and C8 alternately present, and the molecular weight distribution of the MLDPE is 2-2.

5.

4. A method for preparing a gold sand film for use in a gold sand film as claimed in claim 1, characterized in that, The preparation method comprises the following steps: According to the formula of the golden sand film, LDPE, LLDPE, HDPE, MLDPE, POE and TiO2 additives are blended into the extruder according to the blending ratio, the mixed material is extruded through the die head of the extruder and cooled and shaped, the film curtain in the molten state is extruded to form the convex golden sand points by the shaping lines of the embossed counter roller surface, and the golden sand film is obtained.

5. The method for preparing a gold sand film according to claim 4, characterized in that: The screw temperature of the extruder is 150-300℃, the temperature of the die head is 270-300℃, the temperature of the cooling and shaping is 30-40℃, the rubber roller pressure is 5-7 MPa, and the auxiliary machine running line speed is 25-30 m / min.

6. The method for preparing a gold sand film according to claim 4, characterized in that: The gold sand film has a grammage of 18-25 g / m 2 .

7. The method for preparing a gold sand film according to claim 4, characterized in that: The embossed counter roller comprises a pattern roller and a rubber roller, the surface of the pattern roller is provided with a plurality of groups of concave shaping grooves, the plurality of groups of shaping grooves are arranged at intervals and jointly form the shaping lines of the embossed counter roller, and the surface of the rubber roller is smooth.

8. The method for preparing a gold sand film according to claim 7, characterized in that: The adjacent edges of the adjacent shaping grooves intersect.

9. The method for preparing a gold sand film according to claim 7, characterized in that: The shaping groove is in a triangular pyramid structure, the tip of the triangular pyramid structure forms the groove bottom side of the shaping groove, the bottom of the triangular pyramid structure forms the opening side of the shaping groove, and the depth of the shaping groove is 80-100 μm.

10. The method for preparing a gold sand film according to claim 7, characterized in that: The number of shaping grooves per circular area with a diameter of 1.6 mm is 225-400.

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