JPH03128234A - Low glossiness film and manufacture thereof - Google Patents

Abstract

PURPOSE: To obtain a low glossy and elastic matte film having a good touch and a feeling by fixing a skin layer made of a thermoplastic substance to a core layer made of an elastomer substance at a contact part at an interval, and incorporating a mechanical or cross sectional fine wave-like undulation surface. CONSTITUTION: The film 10 is a composite material having a core layer 11 of an elastomer and two thermoplastic skin layers 12. The composite material can be manufactured by a co-extruding process and selectively orienting and relaxation for forming a desired surface section of the layer 12. However, it is on condition that the core layer and the skin layers exhibit a contraction difference of forming a fine wave-like undulation surface. The skin 12 is separated from a surface of the core 11 at a position of a certain interval due to a contraction of the core 11 of the elastomer, and a separate part 13 is generated. This creates a wavy wrinkle surface on the skin 12, and wave wrinkle 14 is entirely enlarged in a cross sectional direction in the wave wrinkle surface.

Description

DETAILED DESCRIPTION OF THE INVENTION BACKGROUND OF THE INVENTION The present invention generally relates to films useful in a variety of household products where elasticity, low gloss, and good "hand and hold" properties are desired. Examples of such uses include diaper linings, colostomy bags, elastic garment closures (eg, sleeve bands, diaper leg bands, and waist bands), and the like. The invention provides, in one part:
Concerning a coextrusion film and its manufacturing method.

Description of the Prior Art Although the film of the present invention is used in a variety of applications because of its unique properties, the disclosure herein emphasizes its use as a diaper lining. Diapers and similar absorbent fabrics such as incontinence garments must possess certain physical properties and certain sensory properties in order to be successful on the market. Diaper linings, eg holding absorbent materials, must have the appropriate physical properties necessary for durability. Also important is the appearance of the diaper, which is necessary to attract the customer's attention. Experience has shown that diapers not only have a matte finish (not less shiny), but also have the appropriate "texture, character"
(“hand”) or “tactile sensation” (“feel”)
and must not produce "plastic" noises when handled. The term "texture, characteristic" or "tactile sensation" is used in the textile industry to describe the feeling upon contact [e.g. roughness].
rough), plastic-like
c), silky, coarse
se), etc.] is often used to describe the properties of textiles. Furthermore, it is important that the diaper fits the wearer comfortably and that the wrap is secure.

Diaper liners with a matte finish are produced by conventional methods by passing the cast film through the nip of a pair of rollers, one of which is a patterned engraved roller or a special sand finish. The film is thus embossed with either a patterned finish or an irregular sand finish, but in either case the result is less gloss on the treated film.

The conventional embossing methods described above have limitations, particularly with respect to economy. Current castline
can produce film at speeds up to 1500 feet per minute, but the embossing process is limited to line speeds of about 700 feet per minute. Furthermore, the "texture, flavor" or "touch" of the embossed film is not very good.

Films with low gloss or matte finishes are widely disclosed in the patent and published literature. For example, Japanese Patent Publication No. 51
-31773, No. 51-311774, No. 56-1
No. 1231 and British Patent Specification No. 1453649
No. 3,843,478 and No. 45
See No. 22887.

Summary of the Invention Low gloss with exceptionally good texture, flavor and feel.
It has unexpectedly been found that a film with an elastic matte finish can be obtained with a coextruded multilayer film comprising an elastomeric core (layer B) and a thermoplastic skin (layer A). The core layer B is substantially flat, while the thermoplastic skin layer A has a microwavy or undulating morphology. The microwavy morphology not only gives the surface of the composite a matte, low-gloss finish, but also improves the tactile properties (i.e., ``hand, hold,'' and ``feel'') of the film.

Additionally, the rubber core layer of the composite material provides elasticity to the garment, so that the fit and wrap (when used in diapers) is much better.

The method for making this film generally includes: (a) coextruding a composite film of ABA in which the skin layer A comprises a thermoplastic material and the core layer B comprises an elastomeric material; (b)
Stretching the composite film to 100% or more of its original length; and (c) relaxing the stretched film. This method produces a film with a skin layer of the aforementioned fine undulations.

Relaxation of the stretched film causes the rubber core to contract more than the thermoplastic skin layer, resulting in the creation of irregular microsurfaces in the composite structure. In the shrink-stretched state, microwavy undulations that are not easily discernible to the naked eye give the film a low gloss and smooth feel. (The term "relaxed stretching state" used here refers to the state of the film after the stretching and relaxing steps in the manufacturing method.) The elastomer core for the ABA structure mentioned above is made of various elastomers. consisting of and/or including. Preferred elastomers include polyisobutylenes (PIB), butyl rubbers, tyrene-propylene copolymer rubbers (e.g. E
PM and EPDM), professional copolymer rubbers (eg SBS, 515. or 5EBS) and mixtures of these copolymers. The skin layer is thermoplastic and is preferably a copolymer of ethylene, such as an ethylene-vinyl acetate (EVA) copolymer.

The range of relative thickness of A and B layers in ABA composites is
The fine undulations created by the shrinkage process are less than 20;
As long as it gives a gloss level of preferably IO or less,
It's spacious and good. Preferred ranges are as follows: A 2.5 to 20 5 to 15B
95-6090-70A 2.5-20 5-15 The total thickness of the multilayer film of the present invention is less than 20 mils and preferably 10 mils or less.

The fine undulations of the skin layer of the film according to the invention are to be distinguished from the embossed or folded finishes of the prior art. The irregular surface created by the former is the result of fine scale gathering, whereas the latter creates surface textures or irregularities by permanent deformation of the film.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, the film 10 of the present invention is a composite comprising an elastomeric core layer 11 and two thermoplastic skin layers 12. The ABA film composite can be manufactured by coextrusion methods (described in more detail below) and selective stretching and relaxation to form the desired surface cross-section of layer 12 (shown in FIG. 2).

The film IO produced in this way surprisingly exhibits the following properties, which make it ideal for many applications.

(1) Good strength properties (in both TD and MD) (2) Matte finish (3) Good texture, hold and feel (smooth) (4) Quiet, non-plastic 'noise' (i.e. (5) High elasticity.

As discussed in more detail below, the compositions of the elastomeric core layer 11 and the thermoplastic skin layer 12 may vary within relatively wide limits. It is assumed that the cardiac and epidermal layers exhibit a contraction difference sufficient to create a finely undulated surface. The terms "rubber" and "elastomer" are used interchangeably herein. and meets the definition of rubber in ASTM D 1566, which is incorporated herein by reference.

Also, "MD" and "TD" are abbreviations for machine direction and transverse direction, and are used in their conventional senses, meaning, respectively, the direction in which the film is processed and the direction perpendicular thereto; .

Elastomer Psychology: The rubber core layer 11 is (a) melt extrudable in the same general temperature range as the thermoplastic used in the skin layer; (b) 100% of its original length.
% or more and can recover a significant amount (preferably more than 50%) of its elongated length; (C) adheres to the epidermal layers; and (d) is generally uniform on the epidermal surface. It must be composed of rubber that is capable of creating a surface cross-section of micro-wavy undulations that are randomly spaced from the epidermis in the swollen position.

Rubbers (elastomeric resins) that can be used in the practice of this invention include both synthetic and natural rubbers, the glass transition temperature (Tg) of the rubber is less than 0°C, and the Shore A hardness is preferably 50 or less. is 40 or less, or 100% modulus is 110 kg
/am” or less or Young’s modulus is 1ooOJ
Preferably, it is less than 29/C-.

Illustrative, non-limiting examples of rubbers suitable for use in the practice of this invention include polyisobutylene (PIB), butyl rubber, halogenated butyl rubber, ethylene propylene rubber (EPM), ethylene −
Propylene diene rubber (EPDM), polyimprene,
Included are polychloroprene, styrene-butadiene rubber, polybutene copolymer, nitrile rubber, chlorosulfonated polyethylene, block copolymer rubber, and the like.

Block copolymer rubbers generally contain 50 to 85% by weight of a central block consisting of a rubbery olefin polymer with equal proportions of ethylene and butylene units, and end blocks of polystyrene (5EBS).

A commercially available block copolymer rubber is Kraton, sold by Shell Oil Company. The central block of other rubbery copolymers is butadiene (5BS) or isoprene (SIS) rather than ethylene butylene copolymers. Preferred block copolymer rubbers have molecular weights of about so, oo.

120,000 to 120,000 5EBS copolymer.

The terms EPM and EPDM are used in the sense in which they are specified by ASTM (ASTMD-
1418-72a). EPM is an ethylene-propylene copolymer that can be crosslinked by radiation curing or peroxide curing.

“E” as used herein and in the claims.
The term "PDM" means a terpolymer of ethylene, a sigma-olefin and a non-conjugated diene.A non-conjugated diolefin is a straight chain, branched chain or cyclic hydrocarbon di-olefin of from about 6 to about Those with 15 carbon atoms can be used.

For example: A, linear dienes such as 1,4-hexadiene and 1,6-octadiene; 8, 5-methyl-1,4-hexadiene; 3,7-dimethyl-1,6-octadiene; 3 .7- Branched chain acrylic dienes such as dimethyl-1,7-octadiene and mixed isomers of dihydro-myricene and dihydrooscinene: C,1,3-cyclopentadiene; 1,4-cyclohexadiene; , 5-cyclo-octadiene and 1.5
- single-ring cycloaliphatic dienes such as cyclododecadiene; D, tetrahydroindene, methyl, dicyclopentadiene: bicyclo-(2,2,1)-hebuta-2,5-
Dienes; alkenyl, alkylidene, cycloalkenyl and cycloalkylidene norbornene, such as 5-methylene-2-norbornene (MNB), 5-globetyl-2-norbornene, 5-(4-cyclopentenyl)-
Polycyclic alicyclic fused and bridged ring dienes such as 2-norbornene, 5-cyclo-hexylidene-2-norbornene, 5-vinyl-norbornene and norbornadiene.

Among the non-conjugated dienes commonly used to make EPDM terpolymers, preferred dienes are dicyclopentadiene, l-4-hexadiene, 5-methyl-2-norbornene and 5-ethylidene-2-norbornene. It is. A particularly preferred diolefin is 5-ethylidene-2-
Norbornene (ENB) and 1,4-hexadiene.

EPDM elastomers and general methods of making them are well known in the art. preferred EP
DIJ elastomers contain from about 20 to about 90% by weight ethylene, more preferably from about 30 to 80% by weight ethylene, and most preferably from about 35 to about 75% by weight ethylene.

α-olefins suitable for use in the preparation of EPDM are preferably C3-C4 'σ-olefins.

Illustrative, non-limiting examples of such σ-olefins are propylene, l-butene, 1-pentene, l-hexene, l-octene and l-dodecene. The α-olefin is approximately I in the EPDIJ polymer.
Generally, it is incorporated in an amount of O to about 80% by weight,
More preferably, it is incorporated from about 20 to about 70% by weight. The non-conjugated diene is present in the EPDM at about 0.5 to about 15% by weight; more preferably about 1 to about 5% by weight, e.g.
wt% incorporated.

The term "nitrile rubber" means acrylonitrile copolymer rubber. A suitable nitrile rubber is 1.3-
It contains a rubbery polymer consisting of butadiene and about 20-50% by weight acrylonitrile.

Average molecular weight is so, ooo or more, preferably about 100.0
“Solid” (“5o
Any commercially available nitrile rubber suitable for the practice of this invention is Rubber World Prop.
Blue Book), 1980 edition of “Materials and Compounding Ingredients for Rubber”
unding Ingredients for Rub
ber''), pages 386-406, which is incorporated herein by reference.

Butyl rubber is a copolymer of inolefin and conjugated polyolefin. Useful copolymers contain a major portion of isoolefins and a minor amount, preferably no more than 30% by weight, of conjugated polyolefins.

Preferred copolymers contain about 85-99.5% (preferably 95-99.5%) of a C4-C7 inolefin, such as imbutylene, and about 15-0.5% (preferably about 5-99.5%) by weight of a C4-C7 inolefin, such as imbutylene. 0.5% by weight) of polyhydric olefins having about 4 to 14 carbon atoms. These copolymers are referred to as "butyl rubber" in patents and literature.
It is called. For example, G, S, Whitby (Whitb)
y) Textbook Synthetic Rubber (Synthet
ic Rubber) (John Willie and Sons,
Ink (John Wiley and 5ons,
Inc., published in 1954), pages 608-609.

This is incorporated herein by reference.

As used herein and in the claims, the term "butyl rubber" refers to about 0.5 to 20% by weight of isoolefins having 4 to 7 carbon atoms and conjugated polyolefins having 4 to 10 carbon atoms. including the aforementioned copolymers consisting of. These copolymers are about 0.5 to about 5
% of conjugated polyolefin. A preferred inolefin is inbutylene. Suitable conjugated polyolefins include isoprene, butadiene, dimethylbutadiene, piperylene, and the like.

Commercially available butyl rubber is a copolymer of inbutylene and small amounts of isoprene. It is generally produced by a slurry process using methyl chloride as the vehicle and a 7 Riedel-Crafts catalyst as the polymerization initiator. An advantage afforded by methyl chloride is that the relatively inexpensive 7-leader delta raft catalyst haca is soluble therein, as are isobutylene and imprene comonomers. Additionally, butyl rubber polymers are insoluble in methyl chloride and precipitate out of solution as fine particles. Polymerization is generally carried out at a temperature of about -90°C to -100°C. U.S. Patent Nos. 2.356.128 and 2,356,12
Please refer to No. 9. They are incorporated herein by reference.

In the halogenation process, butyl rubber in solution is contacted with chlorine or bromine in a series of intensive mixing vessels. Hydrochloric acid or hydrobromic acid is generated during the halogenation process and must be neutralized. For detailed explanation of halogenation method,
U.S. Patent Nos. 3.029.191 and 2,940.
No. 960, as well as US Pat. No. 3,099,644, which discloses a continuous chlorination process. All of those patents are incorporated herein by reference.

The rubbers used in the practice of this invention are preferably used in their unvulcanized state.

Preferred elastomers for films are ethylene propylene copolymer rubber or EP diene rubber (EP
or EPDM) and butyl-based rubber (PIB or butyl rubber) in weight ratios ranging from 3nia to more than 3:3, preferably from 6:4 to 4:6. Although EP or butyl satisfies the elongation properties, the preferred elastomeric core consists of a blend to provide a balance of properties. The crystallinity of the EP rubber provides pellet stability to the blend (ie, prevents agglomeration during processing) and the butyl-based rubber provides low modulus (ie, flexibility) to the film.

The core may contain other additives such as slip agents, block copolymers (eg Kraton), antioxidants or plasticizers (eg refined oils).

The rubber compounding components can be mixed in appropriate weight ratios prior to introduction into the extruder.

Thermoplastic skin layer: Thermoplastics are distinguished from elastomers in that they have substantially inelastic properties. EV
Some thermoplastic resins, such as A, exhibit some degree of elasticity, but the degree of elasticity is less than that required to meet the ASTM D 1566 definition of "rubber." Generally, any thermoplastic resin known in the art to be useful as a film may be used, provided that the film extrudate satisfactorily adheres to the rubber core layer. It can be used as an epidermal layer. Suitable thermoplastic polymeric resins include branched and linear polymers such as polyethylene, polypropylene, polybutylene, polypentene, polymethylpentene, and the like and various copolymers of ethylene and copolymers of propylene.

Ethylene copolymers are particularly preferred as skins because they adhere fairly well to rubber and have some elasticity, and do not compromise the overall elastic properties of the ABA film.

The ethylene copolymer contains ethylene and at least 5% by weight (preferably at least 10% by weight) of an unsaturated ester of a lower carboxylic acid; Preferred is an ethylene copolymer consisting of 8 α-shaped fins. Preferred ethylene comonomers include butene, hexene, and vinyl acetate. Particularly preferred thermoplastic resins are ethylene vinyl acetate (EVA) copolymers, ethylene acrylic acid (FAA) copolymers, ethylene butyl acrylate (EBA) copolymers, ethylene methacrylate (HMA) copolymers, and low density ethylene butene or hexene copolymers ( 5 to 40 and preferably 10 to 35% by weight of comonomer). The ethylene copolymers generally contain 60 to 95% by weight ethylene, but most preferably 65 to 90% by weight ethylene.

The most preferred ethylene copolymer that can be used in the present invention is EVA. EVA is about 5 to 40! The vinyl acetate (VA) content is preferably from about 10 to 35% by weight, and most preferably from 15 to 25% by weight.

VA contents below about 5% by weight do not provide sufficient flexibility and extensibility for the purposes of this invention, and VA contents greater than about 40% by weight exhibit excessive tackiness. The best balance between stretchability and non-stick properties is obtained at a VA content of i5 to 25% by weight.

Preferred melt index of EVA (ASTM-D-
1238, condition E) is 0.5 to 20, preferably 1 to 10, and most preferably 1 to 5.

It may be appreciated that the composite film can have an AB or ABC multilayer structure as well as the aforementioned ABA structure. In the ABC multilayer structure, skin layers A and C may have different compositions, but skin layer A has the composition described above. In this embodiment, the film can be made such that only layer A has the desired surface cross-section described above.

Production of Film 2 The ABA film of the present invention is produced in the following three steps.

(1) Coextruding an elastomeric resin and a thermoplastic resin to form an ABA (or ABC) composite structure.

(Higher line speeds are possible since no embossing rollers are required.) (2) Stretch the composite film preferably in the machine direction (this stretches the ABA layer evenly).

(3) The film is relaxed to cause the cardiac layer to contract more than the epidermal layer, creating a rippled surface in each epidermal layer.

After step 1, the film generally consists of three layers adhered to each other and exhibits relatively high transparency because the outer surface of the skin is relatively smooth. Stretching in step 2 may further increase transparency since it reduces the thickness of the film and tends to make the film surface smoother.

Shrinkage in step 3 surprisingly clouds the film and gives the surface a stringy feel.

As shown in FIG. 2 (which is a !I micrograph of the film magnified 5000 times), shrinkage of the elastomeric core 11 causes the thermoplastic skin 12 to separate from the surface of the core 11 at a distance. separated, and the separated portion is shown as 13. This creates a corrugated surface on the skin 12, and within this corrugated surface the corrugations 14 extend generally in a transverse direction (as shown in FIG. 3) with respect to the direction of stretch.

It is this micro-scale rippled irregular surface that provides the matte finish and smooth slick feel. The irregular surface scatters light and the reduced touchable area gives the film a silky feel.

When the film is stretched again, the undulations or wrinkles tend to disappear, allowing light to be reflected evenly from the film surface, restoring clarity.

Coextrusion of ABA composites is carried out using conventional blending, compounding and extrusion equipment.

The stretching process can be carried out in many ways. For example, in the case of cast film, two godet rolls moving at different speeds can be used to stretch the film in the machine direction. A tenter can be used to stretch the film in the transverse direction.

The film can also be stretched in two directions, in which case the surface undulations may intersect.

In the case of blown film, the stretching is done by “double foam” (“d
This method is carried out by the ordinary in-7 rate sprue method.
ntalk), collapse the bubble, and re-inflate the bubble to a larger diameter.

Stretching is performed one or more times.

Z1 to 3 stretches are sufficient for most films.

The degree of stretching varies greatly depending on the composition of the film, but
100% to 700% of the original length, preferably 200 to 500%, most preferably 300% to 400%. Stretching is carried out at room temperature [65 to 80'F (18 to 27°
0)] is preferably carried out.

The relaxation step is carried out as follows. In the case of godet rollers, tension-free take-off rollers are used. In the case of a tenter, the path of the tenter is positioned to return the film to an untensioned state after stretching.

In the case of blown films, relaxation is accomplished simply by bursting the bubbles. The film reaches a fully relaxed state within about 5 to 10 minutes after tension is released.

Film Properties: Films are characterized by dimensional cross-section, gloss, coefficient of friction and secant modulus.

The dimensional cross-section of the surface of skin layer 12 can be measured by any number of instruments capable of precise surface roughness measurements. One such instrument is the Rank Taylor Hobson
Surtronics 3 (5ur
tronics 3). This meter has a reading of ±2
% accuracy within o-100 microinches.

Gloss is a measure of the transparency of a film and is
D 1003-67. Gloss is 0-1
Represented by a numerical range of 00. Films with gloss ratings of 20 or less are low to medium gloss films, and films reading less than 10 are preferred low gloss films.

For applications such as diaper lining, the matte finish has a gloss level of 1o or less.

Coefficient of friction (COF) was determined according to ASTM D 1894-78.

Tensile and tear strength and secant modulus (which indicates flexibility) were determined by the standard A37M test.

Higashi (Iroki M: ABA film sample, Kirion (
The core resin formulation and the skin resin were coextruded using a Killion extruder. The compositions of the core and epidermal layers were as in Table I (all weights are in % by weight).

The cardiac layer of samples A, B, CFt) and E also Contained small amounts of slip and anti-blocking agents.

The age of each psychological formulation was determined under Condition E.

and The unit is dg/min at 190°C.

The extruder conditions were as shown in Table ■.

B) Kenji Osuda; The physical properties of the film sample "0" were as follows (before stretching): ■Table BCD Tensile, psi (MD) 1135 12
00 1400 1635 Ultimate elongation 1% (MD)
410 400 440 4051% secant modulus, psi (MD) 2500 2500 4200
5000 tear strength, gloil (MD)
41 34 70 900.591 inches (15
The maximum jaw opening is 2.5 mm).
inch (6,35 cm) and 5 inches/minute (12
, 7 cm/min).

The test procedure was as follows.

- Stretch the sample to 100% or 150% elongation and immediately release the stress.

- Stretch the sample three times.

Data (shown in the table) - Modulus, psi - Residual strain after the third cycle; % (indicates the amount of recovery from zero stress) One gloss, before and after stretching (all data are taken when the film sample is relaxed) ) Table 100% elongation - Modulus, psi 345 Residual strain 9% (1) 17 60" gloss unstretched 34 Relaxed stretched state (1) 5 (1) After 3rd cycle 90 8 9 75 0 6 40 7 5 Sample E was made in two thicknesses, a 4 mil thick film and an 8 mil thick film. The properties of these films (before stretching) are shown in Table 7.

Sample E74 was also tested to determine the effect of stretching on the film's secant modulus and COF. The stretched sample is 200~4 of its original length.
00% was repeated approximately 3 or 4 times.

The data are shown in the table.

1% secant modulus, psi MD 1765 720 1355
1150 to 1715 370
1480 1030OF MD >1 0.10 0.58
0.16TD >I O,19>
1 0.58 Gloss 47.2 4.0
59.9 10.4 Surtronic
ic) The surface cross section of sample E was measured using the instrument of 3. ■Table shows surface cross-section data (note that stretched film data is after 3 cycles of 100% elongation and relaxation) Ra - sum of i C above center line The height of an irregular roughness measured by the average distance from a centerline drawn to be equal to the sum of the areas under the line.

Rt - Maximum peak-to-valley value over the sample length.

Rtm - the average peak-to-trough maximum value recorded for the textbook path.

Rpm - average value of the maximum cross-sectional height above the mean line for several paths.

Pc - This peak number is the number of local peaks that stand out from a selectable band centered on the mean line.

This number is determined only by the survey length. However, the results are given in number of peaks per cm (or per inch).

tp% - Support ratio tp% is the length of the support surface at depth p below the high peak (expressed as a percentage of the survey length L).

By making many measurements at different depths p and plotting p against tp%, the support ratio [or Abbott Firestone
one) curve] is obtained.

A combination of Ra and Pc values or Rpm and Pc values may be the best measurement for the surface cross-section of the film.

Comparing these values for the unstretched and relaxed stretched films shows a clear increase in both the size (average) and number of peaks as a result of the stretching and relaxation treatments.

By combining the data of Pc and tp%, the following becomes clear. That is, a relaxed stretched film has much more peaks (greater than 75 microinches) but a much lower support ratio than an unstretched film.

The film of the present invention can be used in at least one direction (MD or TD).
), and preferably have roughness values of:

4 From the data presented in Tables ■ and ■, the following conclusions can be drawn regarding the effect of stretching and relaxing an ABA film consisting of a rubber core and a thermoplastic skin: (1) The surface roughness increases; (2) ) the gloss decreases, (3) the COF decreases, (4) the secant modulus decreases, and (5) the feel of the film changes from plastic-like to rope-like (by observation). .

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a three-layer film that is one embodiment of the present invention. FIG. 2 is a cross-sectional view of an enlarged portion of the film shown in FIG. FIG. 3 is an enlarged top plan view of the portion of the film shown in FIG. 2 showing irregular surfaces. patent application agent

Claims (1)

Claims: 1. A multilayer coextruded film comprising (a) a core layer of an elastomeric material, and (b) one or more skin layers of a thermoplastic material, the skin layer being attached to the core layer. , fixed at spaced apart contact portions, and having a microwavy relief surface in the machine direction or the transverse direction, the film has a gloss rating of less than 20 as measured by ASTM D1003-67. 2. The film according to claim 1, wherein the surface layer has a glossiness of 10 or less due to fine undulations. 3. Fine undulations are 100% in the machine direction or transverse direction
Rpm greater than microinch (2.54 microns)
and a cross section with a Pc of 30 peaks/cm or more, where Rpm and Pc are in the same direction, where Rpm is above and below its center line above and below the machine direction or transverse direction mean line. Maximum height cross section (maximum
heightprofile), and Pc is the number of local peaks projecting from a 75 microinch (1.905 micron) band centered on the mean line of the surface cross-section of the epidermal layer in the machine or transverse direction. The film according to item 1 or 2. 4. The tp% of the film cross section is 75 microinches (1.
905 microns) and less than 25% at p of 30
9 at p of 0 microinches (7.62 microns)
less than 0%, where tp% is the support ratio and the length of the support surface, expressed as % of the probe length in the Rpm and Pc directions at a depth of p below the highest peak. and/or the Rpm of the epidermal layer is 150 microinches (3.81 microns) or more and the Pc is 50
The film according to claim 3, which is above. 5. The elastomeric material is selected from the group consisting of PIB, EPM, EPDM, butyl rubber, block copolymer rubber, and mixtures thereof, and the thermoplastic material is a copolymer of ethylene and a comonomer, the comonomer preferably comprising 3 to 8 comonomers. Olefins containing carbon atoms, or vinyl acetate, methyl acrylate, methacrylic acid,
5. The film of any one of claims 1 to 4 selected from the group consisting of acrylic acid, butyl acrylate, and mixtures thereof. 6. Two thermoplastic skin layers are fixed on either side of the core layer, and the skin layers are fixed to the core layer at randomly spaced apart contact points, such that each skin layer has fine microstructures in the machine or transverse direction. 6. A film according to any one of claims 1 to 5, which has a wavy undulating shape and has a glossiness of less than 20 as measured by ASTM D1003-67. 7. Each skin layer is composed of a polyolefin selected from homopolymers and copolymers of ethylene and propylene, preferably a copolymer of ethylene and a comonomer, the comonomer being vinyl acetate, methacrylic acid,
Any one of claims 1 to 6, wherein the comonomer is selected from the group consisting of acrylic acid, butyl acrylate and olefins containing from 3 to 8 carbon atoms, and the comonomer constitutes from 5 to 40% by weight of the copolymer. A film according to the claims. 8. The film of claim 7, wherein the olefin is selected from the group consisting of butene and hexene, and wherein the olefin constitutes 10 to 35% by weight of the copolymer. 9. The thickness of the film is 10 mils or less;
and/or the core layer constitutes 60 to 95% by weight of the film thickness, preferably 70 to 90% by weight, and/or each skin layer constitutes 5 to 15% by weight. The film according to any one of the preceding claims. 10. The film of any one of claims 1 to 9, wherein when the film is stretched for more than 100% of its length, it has a gloss that is substantially higher than in the unstretched state. 11. The thermoplastic skin layer comprises EVA, VA constitutes 5 to 40% by weight of the copolymer, and the core layer comprises 30% by weight of the copolymer.
8. A film according to any one of claims 1 to 7, comprising a blend of 70% to 70% by weight EPM and 70 to 30% by weight butyl rubber. 12. The film of any one of claims 1 to 7, wherein the core layer comprises a rubber selected from the group consisting of EPM, butyl rubber, block copolymer rubber, and blends thereof. 13. The core layer comprises 25-45% by weight EPM, 25-45% by weight butyl rubber, and 50-10% by weight block copolymer rubber.
The film according to claim 12. 14. The film of claim 12 or claim 13, wherein the block copolymer rubber is selected from the group consisting of styrene-ethylene-butylene-styrene and styrene-butadiene-styrene block copolymers. 15. (a) Stretching a multilayer coextruded film containing a rubber core layer and a thermoplastic skin layer by 100% or more of its original length and conforming the film to ASTM D1003-67.
and (b) relaxing the stretched film such that the core layer contracts more than the skin layer, thereby creating a surface of microwavy undulations in the skin layer; a gloss of less than 20, as measured by ASTM D1003-67, of the film under conditions of: 16. The method of claim 15, wherein steps (a) and (b) are repeated two or more times. 17. The method according to claim 15 or claim 16, wherein step (a) stretches the film by 300 to 500% of its original length. 18. The roughness of the film measured in the stretching direction by the stretching and relaxing process is increased by Ra of 50% or more, Rpm of 50% or more, and Pc of 50% or more, where Ra is the is the height of the irregular roughness measured by the average distance from a center line drawn so that the sum of the areas above the line and the sum of the areas below the line are equal; and Rpm is the average is the average value of the maximum height section above the line;
and Pc is the number of local peaks protruding from a 75 microinch (1.905 micron) band centered on the mean line of the surface cross section of the epidermal layer, any one of claims 15 to 17. The method described in.