JPS6079942A - Grooved film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a diagonally uniaxially oriented film or a laminate thereof that is resistant to curling and has excellent physical strength.

The diagonally uniaxially stretched film has major drawbacks such as residual stress in the diagonal direction and low tear strength in the direction of the stretching axis, and its use as a packaging material, etc. is restricted.

One known method for improving tear strength is to laminate two or more stretched films (cross-laminate) so that the I and -C stretching axes intersect with each other.

(For example, Utility Model Publication No. 55 2'1168, Utility Publication No. 56-19
087, Japanese Patent Publication No. 56 '32139, Japanese Patent Publication No. 57-38
134 etc.). Cross lamination is only effective in improving tear strength. However, it is not sufficient to improve curling properties, and there are other disadvantages due to lamination (high cost,
Further improvements are desired, including an increase in thickness, etc.

The present invention aims to solve the above-mentioned problems.

In the present invention, as a method to solve this curling problem, grooves are formed to intersect the molecular orientation axis of a diagonally uniaxially uniaxially oriented film, and both the curling property and the tear strength are improved at the same time.

That is, the present invention provides a film or a laminated film characterized by having a large number of groove-like irregularities formed by thermoplastic resin with obliquely-axis molecular orientation.

The grooves are typically formed as transverse grooves to the film longitudinal axis, preferably intersecting at 30 to 60 degrees to the film longitudinal axis.

In general, obliquely uniaxially oriented thermoplastic resin films are produced by applying -axis stretching at an angle (5 to 85 degrees) to the longitudinal axis of the film. A typical example is one in which the film is uniaxially stretched at an angle of 45 degrees to the longitudinal axis of the film.

Although uneven shading of films has been widely practiced in the past, there is no known method that focuses on the relationship with the molecular orientation axis to improve curling properties and tear strength, as in the present invention. . In fact, diagonal curls cannot be corrected on silky or matte surfaces, and it is not effective on grooves parallel to the molecular orientation axis.

It is unclear why curling properties are improved by forming grooves that intersect the molecular orientation axis, but the triangular structure formed by the molecular alignment axis and the grooves improves physical strength and curling properties. , it is estimated that

The angle of the groove with respect to the long axis of the film is preferably 75 to 90 degrees.If the groove is parallel to the long axis (R groove), wrinkles will occur, especially in a long roll film, and the production itself will be difficult and loss will occur. Most of them are not practical.

A diagonally uniaxially stretched film can be produced by direct diagonal stretching, but it can also be obtained by slitting a longitudinally axially stretched blown-cylinder tubular film into a spiral shape.

The groove may also be formed using an AHIPL roll (emboss roll) method (it is easiest to form one niche, but an embossing plate is used).

The groove α (first
(see Figure 1) is 5 to 85 degrees, preferably 30 to 60 degrees, and if it exceeds 85 degrees or less than 5 degrees, a sufficient curl prevention effect will not occur. The shape of the groove is not particularly limited, but
The cross section of the groove is wavy.

It may be a trapezoid, a triangle, or any other polygon. Some preferred embodiments of groove shapes are shown in FIGS. 12 to 19.

The grooves can be formed on one side (Fig. 5.7.10) or both sides (Fig. 4s6t8t9) of the film. When grooves are formed on both sides, the grooves on both sides may be parallel or intersect with each other, but the angle of intersection with the molecular orientation axis of the film should be within the above range. As illustrated in FIG. 23, the grooves are typically continuous grooves, but they do not necessarily have to be continuous and may be composed of a combination of discontinuous f:r grooves as shown in FIG. 22. , even a broken line or a chain line is sufficiently effective. However, it is necessary to ensure a sufficient groove length in the predetermined direction.

The pitch of the grooves and the height between the valleys of the unevenness are determined by the film material,
Select according to thickness etc. The pitch of the grooves may be equal or different. In the case of equal pitch, for example 01~
3 In1ll, Preferably 01-2111m,
The amount is also preferably 05 to 1.5+nm. The thickness of the film targeted by the present invention is not particularly limited, but
At least 10 to 200μ, preferably 20 to 70μ. In general, the narrower the pitch, the thicker the resistance to curling.The depth of the groove is not particularly limited and is determined depending on the application, the thickness of the film, etc., and is generally determined by the film thickness. For 171~50 inches, preferably 5~25
A ratio of % is valid. Regarding the films in the above nine ranges,
Practically speaking, a groove depth of 3 to 7 Q It In is suitable;
Especially for general packaging, 5 to 5 Q/I m is more desirable.

Generally speaking, the deeper the grooves, the better the tear strength, curl resistance, stiffness, etc. As a matter of fact, the smaller the area ratio of the remaining part of the groove (the peak), the better the slip characteristics, separation zone, etc. ' The grooved film of the present invention is applied to a single layer film.

However, it is often effective to form grooves on a laminate of two or more layers (especially when grooves are formed on both sides).

The case of a laminate will be specifically explained below as an example of an embodiment of the present invention.

It is known to increase the strength of a two-layer uniaxially stretched film by making it slightly layered so that the stretched layers cross each other.
AF + 瑯 + ] Fl ノ? JI I+ RG wo-y
A I++ 8F −, -1 8i d.

It can be used for jin's 100-'. That is, when two layers of grooved stretched films are laminated so that their stretching axes intersect at 90 degrees,
The grooves are parallel to each other in the lateral direction on both the front and back sides. Such a laminate has greater resistance to curling. In this case, the arrangement of the convex parts on the front and back sides can be matched as shown in FIGS. 15 and 17, or as shown in FIGS. 16 and 19.
It is also possible to make the convex portion on the front side match the concave portion on the back side.

In this case, the tear strength in the lateral direction is stronger in the latter than in the former;
Required impact hole strength. Gas permeability.

You can freely select either one depending on the stiffness, vertical and horizontal characteristics, etc. Further, the grooves (recesses) on the front and back sides may be shifted from each other. The grooves are as shown in Figures 20 and 21.
The film may be shaped into a corrugated shape.

It is also possible to make one layer a stretched film with grooves and the other layer a stretched film without grooves so that the stretching axes intersect. However, in this case, by carefully selecting the thickness of the grooved stretched film, the pitch of the grooves, the depth, etc., the curl resistance is smaller than that of the two-layer grooved film, but it is lower than that of the case without grooves. It's large enough to be used for normal purposes.

When inserting a material with low surface properties, it is advantageous not to have grooves on one side (Figure 10). The reed piece 11ii may be made of a synthetic resin layer with good sliding properties (Fig. 5).

The oblique uniaxially oriented thermoplastic film to which the present invention is advantageously applied includes polyethylene (1■1)PE, LDPli;
.

L, LD, PE), polypropylene, polystyrene,
It is most suitable for materials such as polyvinylidene chloride, polyvinyl chloride compounds, polycarbonate, polyethylene terephthalate, polyamide, etc., which tend to curl easily when stretched diagonally, such as HDPE, polypropylene, polystyrene, etc.

Further, the grooved film of the present invention may be laminated with other films with grooves or without grooves to form a grooved laminated film, if necessary. Other films are selected according to their respective purposes in order to further improve heat roll properties, light shielding properties, strength, dimensional stability, abrasion resistance, cost suitability, etc. (Fig. 4.5.9) ).

It is also useful to use a synthetic resin layer on one side, which is easier to heat-en-roll than polyvinylidene chloride, when a strong seal is required (Figure 4).

Depending on the purpose, the film of the present invention may be laminated with other flexible sheets, such as sheet paper, other synthetic resin films, metal foils, non-woven fabrics, etc. on the surface or in the middle (first
xa5t9 figure). An adhesive layer can be provided as appropriate for laminating these layers (Figures 5.8 and 9.1'O). Further, horizontal grooves may be formed in these heat-sealing layers or flexible sheets (Fig. 4).

When forming grooves with an embossing roll, the depth of the grooves can be increased by increasing the pressure of the press. Also, the higher the roll temperature, the easier it is to form grooves and fix the shape, but it is necessary to avoid melting the film or causing heat shrinkage. Therefore, the temperature is 100°C or lower, usually 20 to 60°C. The same results can be obtained by preheating the film without increasing the metal roll temperature.

11-----・1L Fill+h+J, Il
By providing at least one layer of the wet film with light-shielding properties, it becomes a useful packaging material for photographic materials. This light-shielding property is achieved by using light-shielding substances that are not generally used in packaging materials for photosensitive materials, such as carbon black.
It can be obtained from f7 powder, metal foil such as aluminum foil, etc.

For example, thickness 20 to 300 μn], particularly preferably 30 to 300 μn
150 μn], carbon black fO,,1-159/n? It is preferable to contain reeds from 15 to 71/1 m, and preferably from 5 to 50 p.
m, pitch 01-3mm, more preferably 1 pitch 05-15
The material provided with horizontal grooves of 11 mm is an excellent packaging material for photographic materials.

In addition to adding carbon black, methods for imparting light-shielding properties to the film or laminate include adding other J[t't:
Methods such as addition of substances, printing, and lamination of light-shielding layers such as paper and aluminum foil may also be used. Lubricant in the film,
It is also free to add other additives such as antistatic agents.

As an example of other applications, in the case of a friction sheet for tape rolls such as cassette tapes and VTJS-8 films, (a) a single uniaxial diagonally stretched polyethylene (1-IDPE) film with a thickness of 50 to 500 μm; )) Two layers of this are laminated so that the stretching axes intersect, and (C) (A) is laminated on other flexible sheets such as paper (7). Both of these are effective.

After forming transverse grooves with a roll, an excellent friction sheet can be obtained which has the following advantages whether it is punched out parallel to the grooves or perpendicular to the grooves.

The following is a comparison of the same type of film and laminate with horizontal grooves.

(1) High surface strength and low wear.

(2) Especially the tear strength in the direction of the stretching axis is improved.

(3)! , II separation voltage decreases.

(4) The rigidity is improved and the holding power of the tape roll is increased.

(5) Improved curl resistance. (Especially useful for cassettes) (6) Improves slippage.

This effect can also be applied to film-like members that require similar effects (e.g. container lining materials, sliding member surface materials,
This shows that the present invention is useful as a cushioning material, light shielding material, etc.).

Of course, the product of the present invention is extremely useful not only for photosensitive materials but also for general packaging materials.

Examples are shown below.

-Axis obliquely stretched high-density polyethylene film (density 0, 96 f /
A non-grooved film/lz film of ctd -90/l m thickness is used as a comparative example as conventional product 1. The products of the present invention are passed between a metal roll (35°C) having 5 horizontal grooves per 16 nm and a hard rubber roll to form grooves of a predetermined depth as shown in Table 1. ~4) was produced (
Intersection angle L between the groove and the stretching axis (145 degrees). Next, as an example of a cross-stretched laminate, a -Rat diagonally stretched high-stretched high-density polyethylene film containing 5% carbon black and a stretching ratio of 4 times is used. '96 f/ca N
2 sheets (40 μm thick) of low density polyethylene (LDPE)
so that the stretching axes intersect at 90 degrees through the adhesive layer 10μ,
The bonded product was referred to as Conventional Product 2, and the product in which a 15-μIn-deep lateral groove (angle with the stretching axis was 45 degrees) was formed in the same manner as before was compared as Invention Product 5.

Furthermore, conventional product 3 and invention product 6, in which aluminum foil was sandwiched in the middle, were manufactured. Carbon black content is 5%,
Stretching ratio: 4 times, density: 0.96 f/cTA.

Two sheets of 40 μm thick uniaxially obliquely stretched HD PE films were pasted onto both sides of a 7 μm thick aluminum foil with an LDPE adhesive layer lOμ in between so that the crossing angle of the stretching axes was 90 degrees. This was designated as Conventional Product 3, and the product in which lateral grooves with a depth of 15 μm were formed in the same manner as before (the angle with the stretching axis was 45 degrees) was designated as Present Invention Product 3.

Test results) All of the products of the present invention in which horizontal grooves were formed had improved tear strength, curl resistance, stiffness, sliding properties, and peeling voltage. Moreover, the greater the depth of the groove, the more significant this effect was.

Measurement method Curl value... Vertical s rr in the sort to be tested
A rectangular specimen of n-lateral locm was prepared and left under a 1 kg load plate for 24 hours in an atmosphere of 20°C and 65% humidity.
After leaving the sheet t-1 on a flat plate for 24 hours under a heat load in an atmosphere with a humidity of 65%, the height (mm) of the four corners A, B, C, and D of the sheet from the flat plate was read on a scale.

Tear strength...JIS P8116 Stiffness...
...JIS, P8125 sliding angle ... Cut out a part of each of the above sheets and paste it on the bottom of a block with the same load, while pasting the other part of the sheet cut out in the same way on the inclined surface. When changing the angle by placing the block on this slope, take in the entire angle at which the block starts to slide.The belt is placed on opposing rollers with a load of 500V (upper nylon roller, lower S 1., I). Measure the charged surface with a voltmeter when the charged surface is fed at a speed of 72 m and 7 minutes between S rollers).

[Brief explanation of drawings]

Figures 1 to 3 are conventional products, Figures 4 to io are cross-sectional views of embodiments of the present invention, Figure 11 is a schematic plan view showing an example of molecular orientation direction and groove arrangement, and Figures 12 to 21. 22 and 23 are perspective views +741 showing other embodiments of the groove arrangement. 1a... Oblique anchor stretched film layer 1b...
・Diagonally uniaxially stretched film layer 2 so as to intersect with 1a...Adhesive layer 6...Flexible sheet layer 4 bonded to the middle of the laminated film...・・・・・・Heat seal layer 5・・・・・・Full V flexible sheet layer formed on the surface of the laminated film Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 9 Figure 11 Figure 8 Figure 13 Figure 14 Figure 15 Figure 16 Figure 17 Figure 18 Figure 19 Figure 20 Figure 22Figure 23

Claims (2)

[Claims] (1) At least one surface of the diagonally uniaxial molecularly oriented thermoplastic resin film has a 5 to 8
A grooved film characterized by forming groove-like unevenness forming an angle of 5 degrees. (2) In a laminated film containing at least one layer of a diagonally uniaxially molecularly oriented thermoplastic resin film, all groove-like irregularities forming an angle of 5 to 85 degrees with respect to the molecular orientation axis of the molecularly oriented film, at least one surface of the molecularly oriented film. A grooved laminated film characterized by being formed.