JPH04227781A - New rubber-based self-adhesive tape - Google Patents

Abstract

PURPOSE: To obtain a high-quality novel pressure-sensitive adhesive tape in a cost-effective manner by coextruding a polyolefin and an inexpensive material into a double-layer backing and coating the external surface of the backing with an adhesive.

CONSTITUTION: Copolymer masses 10, 12 emerge as two separate layers through a nip between rolls B, C with a polyolefin layer 10, such as first-grade PE, adhered to the center roll B. The resultant laminate of the layers 10, 12 then advances through a nip of a roll A kept at the m.p. of the layers or above. At that time, a mass of a melted pressure-sensitive adhesive 14 is put on a matte external surface of the layer 12. The tape thus obtd. is then passed through the nip, enters a cooling bath, and is wound around a roll.

COPYRIGHT: (C)1992,JPO

Description

[Detailed description of the invention]

BACKGROUND OF THE INVENTION This invention relates to polymeric films and, more particularly, to cost effective systems for the commercial production of tapes that meet consumer standards and expectations.

[0002] Rubber-based pressure sensitive adhesive tapes have gained wide consumer acceptance not only for industrial tapes but also for virtually the entire line of external protective coatings for pipeline systems. They are sold in a wide range of sizes and thicknesses, depending on the intended application.

In their simplest form, such films are formulations of rubber-based pressure-sensitive adhesives supported on a polyolefin backing so that they do not fold when bent and are impermeable to liquids. Consisting of On the production line for a product known as duct tape, a reinforcing fabric material is sandwiched between the adhesive and the backing for added strength and for lateral tearing.

As readily recognized with any article of manufacture, there is always a need and challenge to reduce production costs by lowering material and/or labor costs. Even for these tapes, the need to reduce production costs is even more severe. This great need is illustrated by the fact that the cost of polyolefin backings has skyrocketed over the past few years. In fact, it is Applicant's understanding that the cost of polyethylene, a standard backing material, has increased on the order of 400 percent over the past several years.

Therefore, in considering measures to reduce the manufacturing costs of these tapes, it is natural to consider that while maintaining production line speeds and throughputs that are viable and cost effective, Attention was focused on reducing the cost of lining.

One possibility, of course, would have been to find a cheaper alternative to polyethylene while maintaining the essential surface properties of the tape. Until now, no such substance has been found.

A second possibility might have been to reduce the thickness of the tape backing and thereby reduce the amount of polyethylene used. Although this is very small,
While it may have been possible without running into tape performance problems or consumer acceptance problems, it is not a viable alternative to meaningful cost reduction.

A third possibility would be to mix other, cheaper materials with the polyethylene to create a homogeneous blend. However, significant amounts of these other materials cannot be blended without loss of quality and performance.

A further alternative, which may be considered as a conceptual starting point for the present invention, is that the outer layer is conventional, ie, first grade polyethylene, and the inner layer (or layers) coated with adhesive is used. ) is to create a multi-layer backing of cheaper materials. Of course, such materials will stick well to adhesives as well as polyethylene top layers;
It is necessary to provide adequate structural stability to resist delamination, so that the product does not lose integrity during storage and use alike.

Materials such as those mentioned below are known and available. For example, something that should be especially noted is what is called dropped selvage that occurs during production in the current production system, that is, the selvedges at both ends of the take-up roll of tape made of backing and adhesive. , various additives, e.g.
Contains tackifiers and fillers for adhesives, colorants, preservatives, etc. This can be reprocessed to provide a molten stock for tape manufacture. Recycled thermoplastics (recovered waste plastics) are also commercially available.

Applicant has proposed that polyethylene and a cheaper material, namely the above-mentioned drop tabs, be co-extruded to create a two-layer backing onto which an adhesive layer can later be applied in a separate coating step. I thought about sex. However, this coextrusion, which requires a separate coating operation to apply the adhesive in a later step, is not a cost effective method from a production standpoint. If manufacturing the backing and applying the adhesive were performed in one step, production would be too slow and require additional space, equipment, and manpower. Furthermore, as will be detailed below, multilayer backings prepared by simply coextruding, for example, onto a moving belt and then cooling can provide the desired film properties, particularly the adhesion applied in a later step. would not provide support for optimal adhesive of the adhesive layer.

Briefly, the task of this invention is to provide a system for making the aforementioned tape having an outer layer of first grade thermoplastic material and a backing consisting of an inner layer of less expensive material. The idea is to devise a system that does not sacrifice quality or production speed and efficiency.

According to the invention, the aforementioned task is fulfilled by utilizing a three-roll calender known per se under certain operating conditions. These operating conditions are: a mass of molten material of first grade polyolefin or other thermoplastic and a mass of molten material of a lower quality, cheaper thermoplastic at a temperature higher than the melting point of the two materials. a first roll or bottom roll heated to a temperature and a second roll or middle roll heated to an elevated temperature below the melting point of the two lumps; The first role is, in fact,
Rotating at a slower speed than the second roll, the two masses are deposited such that the first grade polyolefin mass contacts the second roll first before the nip; Advance between the nip of the first and second rolls to form separate layers, with the inner layer adhering to the center roll being of first grade polyolefin material and the outer layer being of a different, i.e. less expensive, material. The free outer surface of the outer layer has a matte finish and is more receptive to the adhesive to be applied than the smooth outer surface of the first grade polyolefin layer. providing a support; and applying the two-layer backing so formed to the second roll, or middle roll and third roll, of a three-roll calender heated to a temperature above the melting point of the backing; A mass of adhesive is applied in the nip of the second and third rolls by advancing between the nip of the top roll, thereby coating the adhesive over the matte exterior surface of the backing.

[0014] The use of three roll calenders in tape manufacture is quite old and does not by itself form part of the present invention.

For example, issued to Bright,
U.S. Pat. No. 2,631,954, assigned to Kendall Corporation, the assignee of the present invention, includes, for example:
A system is disclosed in which a mass of molten material of an ethenoid polymer, such as polyethylene, is deposited at the nip of the first and second rolls of a three roll calendar. The first roll, which is operated at a substantially slower speed than the second roll, is heated (preferably) to a temperature above the melting point of the particular polymeric material used, e.g. (from within). The second roll is heated (preferably internally) to an elevated temperature below the melting point of the particular polyethylene used, for example 190°F. Since the first roll rotates at a substantially slower speed than the second roll under given temperature conditions, the polymer mass deposited at the nip will be transferred between the nip of the two rolls. It will be extruded to conform to the nip gaps or gaps to form a layer of substantially uniform thickness that will adhere to the surface of the second roll. The layer is then conveyed from the surface of the second roll to a third roll rotating at the same speed as the second roll (relatively cooled with respect to the second roll, e.g. 50°F to with a surface temperature on the order of 70°F). The sheeted layer is stripped from the second roll, looped around a third roll, and then wound onto a take-up roll.

[0016] As stated in the sections from columns 3 to 4, the first roll is preferably rotated at a very slow speed sufficient to equalize the coverage over its entire surface area. The second roll is then adjusted to operate at a higher surface speed. Speed ratio is 5:1~30:
1, preferably when maintained within a range of 15:1,
At the nip, before or during passage through the nip, the polymer mass is subjected to a stretching action under the influence of the friction of the surfaces of the first and second rolls, which are operated at different surface speeds; As a result, before the mass of polymeric material is deposited on the second roll and exits the nip in the form of a sheet, the material molecules are oriented in the direction of its advancement so that the sheet formed on the second roll has a longitudinal orientation. Indicates molecular orientation.

Column 4 states that the sheets exiting the nip have different surface properties. Its inner surface, which adheres to the second roll, is smooth, while the upper surface, i.e.
The other side has a rougher surface and a matte appearance. Differences in surface properties are explained in the patent as a result of action at the nip. It is clear that the portion of the mass that contacts the second roll in front of the nip cools and forms a skin, which is carried into the nip by the forward speed of the second roll. However, the surface of the first roll advances at a slower speed, resulting in drag forces on the material so that the top surface of the sheet leaves the first roll at a speed greater than the speed of the first roll,
As a result, the surface becomes rough.

[0018] As further taught in the said patent specification, the matte-toned, ie, rougher side is suitable for coatings such as solvent-sensitive adhesives, heat-sensitive adhesives, or pressure-sensitive adhesives. It has very favorable adhesive acceptability and retention properties. Accordingly, the specification includes the above-mentioned calendaring (rolling)
This clearly teaches that the application efficiency of adhesive coatings on the rougher, ie, matte, side of the film formed by the method is better than on the opposite, smooth surface.

No. 2,879,547 issued to Morris, also assigned to the Assignee.
No. 5,925,602 discloses a somewhat similar three roll calendering operation for preparing fused film laminates, such as pressure sensitive adhesive tapes. As described and claimed therein, a thermoplastic material, e.g. a plastic material such as polyethylene or a blend of polyethylene and other polymers, is in molten form at the nip of the first and second rolls. The coated film with the resulting matte-like surface is transferred from the second roll to the nip of a third roll, where it is exposed to additional heat introduced at the nip between the second and third rolls. A plastic material, such as a pressure sensitive adhesive, is deposited onto the matte surface.

From the foregoing discussion, it can be seen that prior to the present invention, film or tape backing layers were prepared by applying a mass of one type of polymeric material in a molten state at the nip of two opposing rolls of a three-roll calender; It will be appreciated that it has been known in the art for many years that by advancing a mass of the material through a nip, a film deposited on a center roll and molecularly oriented in the machine direction can be obtained. . Furthermore, the film so obtained is smooth on the surface of application and rough on the opposite surface, i.e.
It is characterized by its matte finish. Furthermore, from the aforementioned U.S. Pat. No. 2,879,547,
The film is then advanced towards the nip between the middle and third rolls, where a mass of adhesive is deposited on the outer surface, making it easier to accept and retain the adhesive. It was known to obtain tapes supported on rough surfaces.

However, prior to the present invention, two different masses of polymeric materials could be deposited in the same nip to form separate, molecularly oriented layers of each while maintaining the integrity of the deposited mass of material. I didn't think it was possible to get it. Rather, people who are extremely familiar with three-roll calenders at Assignee's manufacturing plants, such as those engaged in tape production, believe that the two masses of material are blended together into a single product containing both materials. I believed that the layers would be formed and the thickness of the layers would naturally be determined by the gap between each roll.

In accordance with the present invention, contrary to the negative teachings and prejudices of those skilled in the art, in such a calendaring operation, by following the operating conditions as hereinafter detailed, It has surprisingly been found that it is indeed possible to prepare multilayer backing sheet materials such as: That is, the outer layer is composed of a high-grade thermoplastic polymeric material, such as the polyolefin traditionally used today in tape manufacture, and the free outer surface of the layer is on the support to which the tape is taped. is smooth enough to provide a uniform surface morphology for the adhesive layer of the tape to adhere to when spirally wound or otherwise stacked on the tape, even though the inner layer is made of less expensive polymeric material. is present as a separate layer laminated to the outer layer, and the free outer surface of the inner layer has a roughened or matte appearance, so that the adhesive coating is present as a separate layer, as described below. It is intended to provide optimum surface properties for receiving and subsequently retaining the adhesive layer applied in this way, thereby preventing the risk of delamination of the backing layer/adhesive layer.

The present invention may best be understood by reference to the accompanying drawings in conjunction with the detailed description that follows.

As schematically shown therein, a molten mass 10 of first grade polyolefin and a mass 12 of lower grade, less expensive molten polymeric material containing polyolefin material are each Adjacent rolls B and C are placed separately in the nip of a conventional three-roll calender whose surface temperature and rotational speed are individually controlled.

The first grade polyolefin material may be any polyolefin or mixture thereof conventionally used in the tape manufacturing industry, such as polyethylene, polypropylene, polyisobutylene, etc.
Polyethylene is preferred, as will be discussed later. More specifically, blends of low density polyethylene (LDPE) and high density polyethylene (HDPE) have been found to be particularly suitable for the production of the industrial and/or pipeline protection tapes contemplated herein. It has been.

The second molten mass can theoretically consist of any thermoplastic resin composition as long as it adheres well to both the adhesive layer and the underlying polyolefin layer. Conceptually, it may be more expensive than polyolefins, but it should of course provide some functionality superior to polyolefins to justify its use. It is therefore to be understood that the use of such other formulations is also within the scope of this invention. However, as has been mentioned, to achieve the foregoing objects of the invention, other formulations may be blends of qualitatively lower grade polyolefins, i.e. with polyolefins in the primary layer. , consisting of a mixture of polyolefins with other ingredients making the formulation less expensive than first grade products. Included in the list of such less expensive blends are polyolefin mixtures that fall into the recycled or dropped ear category.

Regarding the former (recycled products), for example, the width is 36 mm before cutting into small rolls during full continuous production operation
It often happens that long tapes, perhaps on the order of 50 or 90 feet in length, fail quality control tests for one reason or another. Since such rolls are comprised of backings, adhesive components and other additives, they are usually relegated to the scrap heap and ultimately discarded. According to the present invention, at least a portion of such recycled product can be mixed with the primary polyolefin for the inner layer to which the adhesive is applied.

[0028] The meaning of the term drop ears used here is, in a certain sense, the same as the above-mentioned recycled product. In a typical manufacturing process, a production roll is first built, which, as noted above, is 36 inches wide or substantially more or less wide. In manufacturing, the backing is made slightly larger in width than the adhesive layer, and both edges of the backing are left unadhered or with ears to prevent adhesive from spilling out. After the winding has been built and cooled, the excess lining on both sides is cut off as ears and only the pure lining material is recycled for use in the main layer. The resulting tape is then cut to the desired width and the outer edges are neatly slit to provide an aesthetically clean and attractive end when rolled onto rolls for sale. Trimmed portions that include both a backing and tape, and are, for example, on the order of 1 to 2 inches in width, are the drop ears contemplated for use by the present invention.

For ease of definition as used in the specification and claims, the term "recycled rubber-based adhesive tape" refers to a polyolefin backing layer and a polyolefin backing layer thereon. means a previously manufactured tape containing both a rubber-based adhesive supported on a rubber-based adhesive, and the molten mass obtained by reheating it above its melting point, in whole or in part, from a cheaper material. It is a thing used as a. [In this connection, it is often said that ``cheaper materials cost nothing,'' but this is probably because conventionally they were of no use and had been discarded prior to the present invention. ] The most important feature for the unexpected result of this invention of providing a distinct layer defining the backing sheet material while retaining the integrity of the two components is that the polyolefin grade material 10 is a continuous material. This means that the mass must first be extruded into contact with the center roll B just before the nip. If this does not occur, mixing of the masses 10 and 12 of the material will occur, the main mass 10 will adhere to the center roll, and the free outer surface of the mass 12 will have a matte or rough finish. It is not possible to obtain mutually separated molecularly oriented layers characterized by .

In a preferred embodiment, each mass 1
0 and 12 are coextruded. Suitable coextrusion equipment for this purpose, for example so-called coat hanger dies with multilayer feedblock feeders, are known in the art and do not form a component of the invention per se. As one skilled in the art will readily understand, the extruder barrel temperature, regardless of the particular coextrusion equipment used,
completely above the melting point of the extrudate, e.g. 300-500°F
It will be in the order of. Also, the operating temperature will be maintained such that the extrudate enters the nip between rolls B and C at a temperature above its melting point. Similarly, it is imperative for the practice of the present invention that the temperature and rotational speed of rolls B and C be within specified parameters.

Specifically, with respect to temperature, the surface of center roll B is heated to an elevated temperature below the melting point of materials 10, 12, particularly preferably from about 160° F. to about 190° F.
and the surface of roll C should be heated to a temperature above the melting point of the material, particularly preferably on the order of about 350°F to about 500°F.

Regarding the rotational speed, the bottom roll C should in fact be rotated at a slower speed than the center roll B. Preferably, the speed ratio of rolls B and C should be in the range 1000:1 to 5:4. For example, if center roll B is 5 to 100 yards/min (
YPM) speed (however, speed calculated using production volume)
If the bottom roll C is set to rotate at
It is set to rotate in the order of %.

Referring again to the drawings, when operated within the above parameters, the polymer masses 10, 12
The first grade polyolefin layer 10 emerges from the nip of rolls B and C as two separate layers with the layer 10 adhered to center roll B. The resulting laminate of layers 10, 12 is then advanced through the nip of roll A maintained at a temperature above the melting point of the layers, for example of the same order of magnitude as the temperature set on roll C, where it is melted. A mass of pressure sensitive adhesive 14 is placed on the matte exterior surface of layer 12. The resulting tape then passes through a nip into a cooling bath from which the tape exits and is wound onto a roll to form a long spool of tape. The winding is then subjected to a longitudinal slitting process and then cut widthwise to produce a series of small windings of the desired width and length. All these operations are carried out by methods known per se.

Regarding the rotation speed of roll A, it is known in the art that roll A should not normally rotate faster than roll B, since center roll B is the driving force that determines the speed of the production process. A skilled person will understand. Apart from that, the rotational speed of roll A is not critical to the practice of the invention and may be, for example, on the order of about 1.0 YPM.

[0035] The particular adhesive applied in the calendering process of the present invention is chosen at the discretion of the skilled artisan, depending on the desired properties and anticipated use.

A wide range of calenderable thermoplastic adhesive formulations are known in the art. Preferred are commonly used rubber-based pressure sensitive adhesives. Such adhesives typically consist of at least one rubber-like elastomer (a polymer with rubber-like properties) and at least one tackifying resin, in addition to imparting certain desired functionality. other additives such as colorants such as carbon black or titanium dioxide, fillers, antioxidants, etc. Suitable elastomers include natural rubber, cyclized rubber, styrene-butadiene copolymer (SBR), acrylonitrile-butadiene copolymer (NBR), chlorinated rubber, polychloroprene (neoprene), hydrochloric acid rubber, polysulfide rubber (polysulfide), rubber), carboxyl elastomer, silicone rubber, polyurethane rubber, acrylonitrile-butadiene-styrene (ABS), recycled rubber, butyl rubber, polyisoprene, polyisobutylene, ethylene-propylene-diene monomer terpolymer rubber (EPDM), Rubbery polymer “KRATON” (Shell Che
mical trademark) family, etc. The thickness of each gap between the rollers and, in turn, the thickness of the backing layer and adhesive layer formed in the practice of this invention, as with the previously prepared tapes, will vary as desired.

The following examples are intended to specifically illustrate the invention and are in no way intended to limit the practice of the invention.

[0038]

EXAMPLE A three-roll kneading machine as described above, equipped with means for internal heating, was set up under the following operating conditions: Rolls
Temperature Rotation speed Top roll A
350°F 1 YPM
Center roll B 1
83°F 10 YPM
Bottom roll C 364°F
To prepare tapes with a total thickness of 0.5 YPM on the order of 25 mils, the gap between the bottom roll and center roll for the backing was set at approximately 20 mils, and the gap between the center roll and top roll for the adhesive layer was set at approximately 20 mils. The gap was set at approximately 25 mils.

52% LDPE, 40% HDPE, 7
% white concentrate and 1% antioxidant blend (prime polyolefin component); 40% H
A blend of DPE, 25% LDPE and 35% slitter drops as previously described was prepared for the cheaper layer.

A standard rubber-based pressure sensitive adhesive formulation consisting of about 1/3 butyl rubber, about 1/3 tackifier, and 1/3 clay filler was used to prepare the adhesive layer.

Using a coathanger coextrusion die with a multilayer feedblock set at an internal temperature of about 450° F., a first grade polyethylene blend and a less expensive backing blend were mixed between rolls B and C. The product blends were coextruded such that they first contacted roll B before the nip. When the extruded mass of material passes through the nip, two virtually equal layers are formed, each approximately 10 mils thick, with the first grade layer adhering to roll B and another layer forming. was adhered to Roll C and had the expected matte outer surface. As the two layers pass through the nip, the outer, cheaper layer peels off from roll C;
The composite laminate is conveyed to the nip between rolls A and B, where the now extruded adhesive mass is placed on the matte exterior surface of the two-layer backing. Ta. When the adhesive-containing backing sheet passed through the nip, an adhesive layer approximately 5 mils thick was deposited thereon.

The long roll of tape obtained was then cut to the desired width and cut to the desired length in a manner known per se.

In the above illustrative embodiment, the relatively inexpensive mass of material coextruded to form layer 12 consisted of a mixture of 65% first grade material and 35% drop selvedge material. It will be observed that In this example, approximately 17.5%
savings in first-grade materials were obtained.

In the example described above, only a small portion of the first grade material was replaced with cheaper material;
It should be clearly understood that the present invention contemplates replacing all or part of the first grade polyolefin in layer 12 with an inexpensive polymer blend.

[0045] As a solution to the problem of the present invention, the cost-effectiveness of the present invention is to replace some of the polyolefin materials typically used heretofore to form backing sheets with less expensive materials. Although the invention has been described in detail in the foregoing description using examples of manufacturing methods that are effective in the following, it is further to be understood that the invention is not so limited.

In this regard, it will be appreciated that the present invention provides a one-step calendering method in which two different polymeric materials are fed into the same nip to obtain separate layers. It is therefore clear that production cost is not a criterion for carrying out the spirit of the invention as taught in the foregoing description and that any two mutually compatible polymer blends can be used.

As used in the specification and claims, the term "compatible" refers to the term "compatible" as used in the specification and claims to mean that they do not interact adversely with each other and that the two are tightly coupled to form a useful layered structure. means a blend of polymers that Similarly, it will come to mind that polymer formulation 14 need not necessarily be a pressure sensitive adhesive, or for that matter, an adhesive at all. It has opposing outer surfaces with the same or different chemical and/or
or other non-adhesive thermoplastic materials to form a three-layer sheet material exhibiting physical properties.

Throughout the description so far, reference has been made exclusively to the use of polyolefins. While polyolefins are certainly preferred materials as tape backings, it will be appreciated that the invention in its broadest aspects is not limited thereto. Other thermoplastic materials that can be used in the practice of this invention will readily occur to those skilled in the art in light of the foregoing description.

Although many modifications may be made without departing from the scope of the invention as described herein, it is the intent of this specification to incorporate the entirety of the foregoing description, including the drawings and examples. These matters are just examples and do not limit the present invention in any way.

[Brief explanation of the drawing]

1 is a schematic diagram illustrating the manufacturing method of the present invention, with the thickness of the tape material greatly exaggerated with respect to the dimensions of the roll, for the purpose of clearly illustrating the invention; FIG.

[Explanation of symbols]

A Top roll of a three-roll calender B Center roll as above C Bottom roll 10 as above A molten lump of first-grade polyolefin (or
adhesive tape backing layer)

Claims (27)

[Claims] Claims: (1) providing a gap between the rolls of a calendar having two stacked rolls, first and second, which limits the thickness of the sheet material produced in the calendar; The temperature of the first roll is adjusted to a temperature above the melting point of each of the first and second different thermoplastic polymer materials, and the temperature of the second roll is adjusted to an elevated temperature below the melting point of each of the materials. (3) adjusting the rotational speed of said first and second rolls such that said first roll rotates substantially slower than said second roll; (4) said first and second rolls; A second polymeric material in molten form is deposited by extrusion on the rolls such that the first polymeric material is deposited by extrusion before the nip between the rolls and first contacts the second roll. (5) advancing both of the deposited polymeric materials between the rolls, between the rolls, the first material is deposited on the second roll, and the second material is deposited on the second roll; adhering to the first roll, thereby forming a multilayer sheet comprised of distinct layers with molecular orientation in the machine direction; and (6) subsequently advancing the sheet to transfer the second material to the second roll. A method of preparing a multilayer sheet from first and second different thermoplastic polymeric materials, the steps comprising: peeling from a single roll; 2. The method of claim 1, wherein said first polymeric material consists essentially of the highest commercial grade polyolefin. 3. The method of claim 2, wherein said polyolefin comprises at least one type of polyethylene. 4. The method of claim 2, wherein said polyolefin comprises a mixture of high density and low density polyethylene. 5. The method of claim 1, wherein said material is coextruded proximate the nip of said first roll and center roll. 6. The method of claim 2, wherein the second material is of lower cost than the first material. 7. The method of claim 6, wherein said second material is a dropped polyolefin mixture. 8. characterized in that the surface of the first layer of the sheet adhering to the second roll is essentially smooth; 2. The method of claim 1, wherein the outer surface of the layer is roughened to be more receptive to adhesive. 9. A multilayer sheet material prepared by a method as defined in claim 10. 10. The surface of the second roll is about 160°.
2. The method of claim 1, wherein the first roll has a surface temperature of about 350<0>F to about 500<0>F. 11. The rotational speed ratio of the second roll and the slowly rotating first roll is about 1000:1 to about 5.
4. The method of claim 1 in the range of :4. 12. The center roll rotates at a speed of from about 5 to about 100 yards per minute in terms of throughput, and the first roll rotates at a speed up to about 0.1 yards per minute of the speed of the center roll. 12. The method of claim 11, wherein the rotating speed is up to 80 percent. (7) The sheet material carried on the second roll is transferred to a third roll placed on the second roll (the surface temperature is the melting point of the sheet material). (8) applying a melting point lower than the temperature of the third roll onto the free outer surface of the multilayer sheet material at the nip between the second and third rolls; and (9) passing the sheet material coated with the third material through a nip between the second and third rolls. The method described in 1. 14. The method of claim 13, wherein the third material is an adhesive. 15. The method of claim 14, wherein the adhesive is a pressure sensitive rubber-based adhesive. 16. An adhesive tape prepared by the method of claim 15. 17. A method of preparing an adhesive tape consisting of an adhesive layer carried on the surface of a multilayer sheet material consisting of discrete layers with molecular orientation in the machine direction, comprising:
The outer layer of the sheet material is comprised essentially of the highest grade commercial grade polyolefin material, the inner layer is of a lower cost grade of polyolefin, and the outer surface of the outer layer is essentially smooth. The inner layer carrying the adhesive layer has a roughened outer surface and has good adhesive receptivity and adhesive retention, and the method for producing the adhesive tape comprises: :(1) Three rolls consisting of a first roll, a center roll, and a third roll, arranged so that the first roll and the center roll and the center roll and the third roll overlap, respectively.
(2) the first and third rolls are above the melting point of the material forming the layer of sheet material; temperature, and adjusting the surface temperature of each of the rolls so that the center roll is at an elevated temperature below the melting point of the material; (3) the first roll is substantially more effective than the center roll; adjusting the rotational speed of each roll so that it rotates slowly and the rotational speed of the third roll is not greater than the rotational speed of the center roll;
4) a first molten material of the polyolefin material to form the outer layer and a second molten material of the polyolefin-containing material to form the inner layer, the first molten material being a first roll; (5) depositing proximate to the nip between the first roll and the center roll such that it is deposited by extrusion before the nip between the center rolls and in contact with the center roll first; Both the deposited materials are advanced between the first and second rolls so that the material adheres to the center roll and the second material adheres to the first roll, and both the adhesive materials are removed. present as separate layers, thereby forming the multilayer sheet material having the smooth surface adhered to the center roll;
(6) continuing to advance the sheet material to strip the second layer from the first roll so that the outer surface of the stripped second layer is roughened and resistant to adhesive; (7)
) advancing the sheet material carried by the center roll further toward the nip between the center roll and a third roll; (8) moving the molten thermoplastic adhesive material between the center roll and a third roll; deposited on the roughened surface of the sheet material at the nip between; and (
9) advancing the adhesive coated sheet material between the center roll and a third roll to form the tape; 18. The method of claim 17, wherein the first and second materials are coextruded proximate a nip between the first roll and a center roll. 19. The method of claim 18, wherein the first material consists essentially of polyethylene and the second material comprises a dropped polyethylene blend. 20. The surface of the center roll is about 160
19. The method of claim 18, wherein the temperature of the first and third rolls is in the range of about 350<0>F to about 500<0>F. 21. The rotational speed ratio of the center roll and the slowly rotating first roll is about 1000:1 to about 1000:1.
21. The method of claim 20, wherein the ratio is about 5:4. 22. The center roll rotates at a speed of about 5 yards/minute to about 100 yards/minute in terms of production, and the first roll rotates at a speed of about 0.1 yards/minute to about 100 yards/minute, in terms of production rate. 22. The method of claim 21, wherein the method rotates at a speed of up to 80 percent of the speed of. 23. The method of claim 17, wherein the adhesive comprises a rubber-based pressure sensitive adhesive. 24. characterized in that the outer layer consists essentially of the highest grade polyolefin material, the inner layer is less expensive and includes a polyolefin material, and the outer surface of the outer layer is substantially smooth, The outer surface opposite the inner layer carrying the adhesive layer is roughened and has better adhesive receptivity and adhesive retention than the smooth outer surface of the sheet material. Adhesive tape consisting of an adhesive layer supported on one surface of a multilayer sheet material. 25. The tape of claim 24, wherein both said polyolefins consist of polyethylene. 26. The tape of claim 25, wherein the polyethylene in the inner layer is encapsulated in a droplet mixture. 27. The tape of claim 25, wherein the adhesive layer is a formulation of a rubber-based pressure sensitive adhesive.