JP2001247684A - Molded resin printed on its uneven surface part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To develop a molded resin characters printed on the surface of which hardly disappear and by which an indication can be stably maintained even when receiving a physical action during using the resin. SOLUTION: A molded resin printed on the uneven surface part has 30-100 μm in depth on the uneven surface part and is printed with ink on the uneven part wherein the sum total (nS2) obtained by multiplying an ink area (S1) printed on the uneven surface part by the number (n) of the surface (S2) around the convex part present in the ink area is calculated according to the formula: (S1-nS2)/S1/×100, the population Y(%) of the concave is 10-80%, and the diameter around the convex is 5-20 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed molding resin and a method for producing a molded resin printed on the surface of a molding tree when molding the resin.

[0002]

2. Description of the Related Art Resin moldings such as resin packaging materials and resin containers,
In particular, the surface of a molded article of a polyolefin resin generally has high liquid repellency and poor surface wettability with respect to printing ink or the like. There was an inconvenience that the printing disappeared due to weak physical action. There is also a commercially available product in which the expiration date or the like is printed on the top surface outside the container cap without any irregularities. In this case, the print was not erased by rubbing with a fingertip, but when the cellophane tape (registered trademark) was applied, the print was completely transferred to the cellophane tape, and no characters remained on the cap. In addition, if the fingertip on which grease, detergent, or emulsified food adheres is touched to the printed characters and lightly rubs it, the characters will gradually disappear, and if the components such as food inside the container are attached to the fingertips, etc., the contents will be consumed if the printed characters are touched Before doing so, there is a disadvantage that characters such as the expiration date disappear. There is also a commercially available cap for food that has a notch on the outer top surface of the molded resin and has characters printed on this surface. However, if a cellophane tape is similarly applied, the character disappears to a degree that it is difficult to read at a time.

As a solution to this, printing has been performed after the resin surface is subjected to corona discharge or flame treatment, and the resin surface is treated. When a large surface area of the container is subjected to the surface treatment by the above-described method, a blocking phenomenon occurs in which the contact surfaces adhere to each other during the storage or transportation due to contact between the containers. Therefore, Japanese Patent Application Laid-Open No. H10-95866 discloses that printing is performed after corona discharge or flame treatment is performed only on a printing portion. When printing after these surface treatments, the characters are fixed firmly on the resin surface and the preservation of the characters can be maintained well, but when incorporating them into the product production line at the factory, use a flame generator or corona discharge machine. We need to prepare. At least one additional production process is required and capital investment is required. When a flame generating device is provided, a gas burner is required, which is not preferable in view of fire prevention and other safety at a production site. In the case where the surface of the resin molded body is made uneven by sandblasting, an extra step is required, which hinders productivity, makes it difficult to prevent generation of dust, and may cause generation of dirt and foreign matter.

[0004]

SUMMARY OF THE INVENTION According to the present invention, characters printed on a resin surface are hardly erased even when subjected to a physical action while using the resin, and the display is stably maintained. An object of the present invention is to provide a printed resin molded body that can be printed and a method of molding the printed surface thereof.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems. As a result, the Magic Ink (registered trademark) pattern drawn on the uneven surface has a higher friction resistance than the surface without unevenness. The present inventors have found that the annihilation is small and completed the present invention.

That is, the present invention has a depth of 30 to 100 μm.
Molding resin having surface irregularities, and a depth of 30 to 1
It has a surface unevenness of 00 μm, and the concave portion occupancy Y (%) is Y
= (S1-nS2) / S1 × 100 The value of Y (provided that the ink area printed on the surface irregularities is (S
1) The area around the skirt of the convex portion existing in the ink area is (S
2), the number (n) is 10 to 80%, and the diameter around the skirt of the convex portion is 5 to 20 μm. Molding resin. Another invention is to transfer a mold concave portion to a molded resin surface by molding a resin using a mold having a concave portion having a depth of 30 to 100 μm corresponding to a surface uneven portion of a molded resin. This is a method for producing a molded resin having a surface irregularity.

[0007]

As for the irregularities on the surface of the molded resin, which is one of the requirements of the present invention, the height of the projections (depth of the depressions), the diameter of the projections and the density of the projections are important. Depth 30-100 provided on the surface
μm is readable when the printed character is viewed diagonally upward with the naked eye, and remains on the concave portion even when the uneven ink surface is rubbed with a fingertip or the like and the attached ink is wiped off. It is at least readable by ink. It is set within a range to avoid distortion of the character or difficulty in reading due to excessive depth in the unevenness depth direction. 30 μm depth
If the size is smaller, the printed characters have no durability against rubbing and easily disappear. 30-100 deeper than this
Even if it is rubbed, the ink does not remain in the concave portion even when rubbed, and the characters do not disappear at an early stage. But 10
When the depth exceeds 0 μm, the ink persistence increases, but the position of the ink becomes deeper. Therefore, when a person looks directly from above, the characters can be read clearly, but when viewed slightly diagonally, the characters are legible. Characters may not be legible depending on the difficulty or viewing angle. Further, when the concave portion becomes deep, printing by an ink jet printer is effective as a printing method. Since the printed characters exist deep in the concave portions, the durability against rubbing is increased.

[0008] The diameter and density around the skirt of the projection are also important.
The convex portions are transferred to the concave portions of the mold at the time of molding the resin. The shape of the periphery of the convex portion shown in a projection view from above is substantially circular. There are some coves in the processing conditions, but here we define them as substantially circular to avoid complexity. The ink surface printed from the diameter of the ink jet is usually circular, and for printing on the container cap, the diameter is within a practical range of 20 to 100 μm. For example, if the ink jet aperture is 30
If it is μm, the area of one dot after printing is about 40 μm square. The dots form a character in a series of dots. The density of unevenness and the circumference of the ridge of the convex portion existing in one dot affect the durability of the printed character at the time of rubbing. 5 to 15 around the hem
μm is preferred. The reason is that the density of the convex portions is at least three convex portions (at least one concave portion) in one dot.
The existence of is required. In addition, the distance between the projections must be so close that the depressions do not touch the rubbing of a finger or the like.
If the protrusions are higher, the recesses become deeper, so that even if the distance between the protrusions is increased, the ink in the recesses remains without being affected by rubbing. However, increasing the height of the projections increases the depth of the depressions, so that the mold releasability tends to deteriorate.

[0009] The area of the ink (S
1) and the area (S
The sum (nS2) obtained by multiplying the number of protrusions (n) in 2) by the formula (S1−nS2) / S1 × 100 is 10 to 80% for the recess occupancy Y (%), and the ink area is 40
Y is 10% when μm and the diameter around the skirt of the projection is 10 μm
, 14 to 15 protrusions within the ink area, 80
In the case of%, it is 3 or 4. These states can be said to be states where the convex portions are densely present practically to achieve the object of the present invention.

As a method of providing irregularities on the molding resin surface,
If it is possible to provide a concave portion on the mold surface corresponding to the molding resin surface, it is practical because irregularities are provided at the same time as the resin is molded. In order to provide a concave portion in the mold, a sand blast method, a chemical treatment, and a corona discharge are usually used. Specifically, using a mold having a concave surface having a depth of 30 to 100 μm corresponding to the surface irregularities of the molded resin, the resin concave is transferred to the molded resin surface by molding the resin. Comes out. This molding process is preferably injection molding.

The ink used for printing is an ink in which a dye is dissolved in an organic solvent. The use of the organic solvent varies depending on the ink maker, but methyl ethyl ketone is usually preferred as the solvent. As a printing method using ink for the purpose of the present invention, printing using an inkjet printer is preferable. The reason is that when printing is performed on the uneven surface, the ink is applied and injected to the deep portion of the concave portion.

[0012]

The present invention will be described more specifically with reference to the following examples. The test method used in the examples is described below. <Cellophane tape peeling test> A commercially available cellophane tape is applied to the printed surface, and the upper surface of the cellophane tape is rubbed with a finger three times, and then peeled off, and the legibility of the character transferred to the adhesive surface of the cellophane tape, the legibility of the printed character, and immediately after printing Compare the ink density with The evaluation results are shown below. A: No transfer to cellophane tape, and printed characters are clearly readable. ；: The printed characters are slightly readable, but the printed characters can be easily read. Δ: Transfer characters can be easily read. Printed characters can be read. ×: Transferred characters can be clearly read. The printed characters are difficult to read. <Wetting test> The test was based on the wetting test method of JIS K6768 polyethylene and polypropylene film. <Transportation Endurance Test> Products filled with food in actual packaging were packed in cardboard boxes, transported by truck for about 1,000 km, and the durability of printed characters on the top surface of the cap and the protective sheet was evaluated. The evaluation results were evaluated in four stages. A: No printed characters were damaged at all. ；: The print characters are somewhat faint. Δ: Printed characters became pale but legible. X: Printed characters disappeared and were unreadable. <Measurement of height and skirt circumference of convex part> Using a video camera OVM1000 manufactured by Olympus Optical Co., Ltd., enlarge the ink printing area using a CCD camera, print out necessary images while monitoring the image, and print this image. The length around the skirt of the convex portion was measured based on the above. <Measurement of Depression Occupancy (Y)> The Olympus Optical Co., Ltd. video microscope OVM1000 was used to enlarge the ink printing area using a CCD camera, print out the required image while monitoring the image, and print this image. The length required for the base was measured, and the sum of the area around the protrusion hem was calculated from the following formula based on the ink area (S1), the area around the protrusion hem (S2) present therein, and the number of protrusions (n). . Y (%) = (S1−nS2) / S1 × 100

[0013]

Example 1 <Manufacture of mold for molded resin cap having surface irregularities> In order to provide irregularities on the top surface of molded resin, an injection mold corresponding to this surface has an average depth of 30 μm.
m and 40 μm concave portions were provided by corona discharge. The diameter of the hole at the time of depression of each recess is 6 to 13 μm, respectively.
The density is 6 to 15 μm, and the density is 5 to 15 in 40 μm square. <Production of molded resin cap having surface irregularities> A high-density polyethylene molded resin cap is molded by an ordinary method using an injection molding machine using the above-described mold, and an average of 30 μm (25 to 25 μm) is formed on the top surface of the cap. 35 μm) and average 40 μm
A bottle cap having a projection of (35 to 45 μm) was manufactured. The projections were transferred and molded on the upper top surface, but the density of the projections was 5 to 15/40 μm 2, so that the entire upper top surface was uneven. 30 μm and 40
If the top surface of the cap on which the μm convex portion was transferred was rubbed with a finger, the roughness was clearly recognized in both cases. Table 1 shows the state of the irregularities on the outer top surface of the manufactured cap.

[0014]

[Table 1]

[0015]

Comparative Example 1 <Production of Molded Resin Cap without Surface Irregularities> A high-density polyethylene molded resin cap was molded by a usual method using a compression molding machine using a mold having no concave portions. The top surface of the cap is smooth (no irregularities), the height of the convex portion is 4 μm (3 to 5 μm) on average, and the average is 7 (5 to 10 μm).
μm) and an average of 15 μm (10-20 μm). If the upper surface of the cap is stroked with a finger, the roughness is 3 to 5 and the degree of roughness cannot be recognized.
Was able to sense the roughness. Table 1 also shows the state of the irregularities on the outer top surface of the manufactured cap.

[0016]

Example 2 <Manufacture of molded resin cap having surface irregularities printed with organic solvent-based ink> A bottle made of a soft packaging material (600 ml) capable of squeezing out filled food is used as a bottle transport belt in a normal production line. After being placed on a conveyor and filled with foods, the bottle was covered with the cap produced in Example 1. Next, an ink jet (170i-U manufactured by VideoJet Japan Co., Ltd.) set 10 mm above the top surface of the cap
HS type), an organic solvent-based ink (16-8420 manufactured by VideoJet Japan, using a methyl ethyl ketone solvent) is ejected from the ink discharge port, and the characters "Best before date 2000.
1.17 "was printed in two columns.

[0017]

Comparative Example 2 <Production of Molded Resin Cap Printed on Uneven Surface> The cap manufactured in Comparative Example 1 was printed in accordance with Example 2.

[0018]

Example 3 Various tests were conducted on a molded resin cap in which the surface irregularities obtained in Example 2 were printed with an organic solvent-based ink.
The results are shown in Table 2.

[0019]

[Table 2]

[0020]

Comparative Example 3 A molded resin cap was subjected to various tests in accordance with Example 3 except that the cap obtained in Comparative Example 2 and having no top surface having uneven portions was used. The results are also shown in Table 2.

[0021]

COMPARATIVE EXAMPLE 4 A cap having no irregularities was used on the outer upper surface produced in Comparative Example 1, and the outer upper surface was flame-treated using a gas burner. Next, using an ink jet printer,
"Expiration date 2000.1.17" was printed. This was subjected to a cellophane tape peeling test, and the result was ◎. The result of the transport test was also ◎.

[0022]

According to the present invention, even when a character printed on the surface of a molded resin is subjected to a physical action while using the molded resin, the character is hardly erased and a stable display can be maintained.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of the size and density of a single ink droplet and a convex portion obtained from an image of a single ink droplet printed on the outer top surface by a CCD camera. The size of one drop of ink is about 40
μm 2. The diameter around the skirt of the convex portion is approximately A8 μm, B is 5 μm, C is 3 μm, and D is 7 μm.

FIG. 2 is a photograph when a print group surface is captured by a CCD camera and projected onto an image, and the heights of the convex portions are A to 20 μm, B to 10 to 20 μm, C to 5 to 10 μm, and D to 5 μm. -10
μm.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) C08L 101: 00 C08L 101: 00 (72) Inventor Susumu Fujiwara 1-27-17 Inugura, Miyamae-ku, Kawasaki City, Kanagawa Prefecture. (72) Inventor Tsutsuya Muronaka 2-26-18 Hiyoshi, Kohoku-ku, Yokohama-shi, Kanagawa Prefecture (72) Inventor Yoji Arari 2-3-4, Sukugawara-Gen, Tama-ku, Kawasaki-shi, Kanagawa F-term (reference) 3E062 AA09 DA02 DA09 4F071 AA02 AA14 AH04 AH05 BB05 BC08 BC10 4F202 AA05 AF01 AG05 AH57 CA11 CB01 CB28 CB29 CK11

Claims (4)

[Claims] 1. A molded resin having a surface unevenness having a depth of 30 to 100 μm. 2. A molding resin having a surface unevenness having a depth of 30 to 100 μm, and having the unevenness printed with ink. 3. The concave portion occupancy Y (%) is Y = (S1-nS
2) The value of Y calculated by / S1 × 100 (however, the area of the ink printed on the surface unevenness is (S1), the area around the skirt of the protrusion existing in the ink area is (S2), 3. The molded resin printed on the surface irregularities with ink according to claim 2, wherein n)) is 10 to 80% and the diameter around the skirt of the convexities is 5 to 20 μm. 4. A mold having a concave portion with a depth of 30 to 100 μm corresponding to a surface irregular portion of a molding resin,
A method for producing a molded resin having surface irregularities, wherein a mold concave portion is transferred to a molded resin surface by molding the resin.