KR100497591B1 - Adhesives comprising linear, isotactic polymers - Google Patents

Abstract

The present invention is directed to an adhesive containing a polymeric material whose structure comprises nanoscale-sized elastic amorphous regions reinforced with self-aligned crystalline domains of nano-crystals.

Description

Adhesives Containing Linear Homogeneous Polymers {ADHESIVES COMPRISING LINEAR, ISOTACTIC POLYMERS}

The present invention relates to adhesives for use in assembling articles, for example. Specifically, the present invention relates to an elastic adhesive.

Adhesives, especially adhesives containing olefinic polymers, are well known in the art and are widely used throughout the industry. Typical areas where the adhesive is applied include hygiene articles, in particular disposable absorbent articles, packaging materials, automotive parts and the like.

Adhesives made from commonly used polyolefins such as PP, PE, PS, PIB have many useful properties. These are bio-compatible and food compatible, chemically stable, inert, non-toxic materials. However, most of these have poor mechanical properties, including insufficient strength / tear resistance, insufficient elongation / elasticity, and the like.

Other adhesives such as PU base adhesives are also widely used, for example due to their elasticity. However, PU adhesives have the disadvantage that they are not applicable much because of their inherent toxicity due to the residual monomer content since they are polymerized from the very toxic monomer isocyanates.

Several approaches have been proposed in the art to provide elasticity to the adhesive. The most commonly used approach is based on changing the chemical structure of the polymer by introducing a hinged bond / part into the polymer's backbone. The side groups or side chains prevent crystallization of the polymer, lower the glass transition temperature (Tg) and improve the elasticity of the resulting material, giving more flexibility to the polymer backbone. Typically, the hinge group contains heteroatoms that impart flexibility, such as oxygen, nitrogen, or chlorine, located in the main chain or bulk side groups. Another approach is to masticate the polymer by blending certain plasticizers. However, both approaches require heteroatoms to be introduced into the bulk of the molecule or coating material.

Closer to the present invention, a third approach conventionally proposed in the art to provide elasticity to the adhesive is to develop a hetero-phase formation that reinforces the bulk material by forming a physical net. To this end, block copolymerization of two or more different monomers was used to derive a polymer backbone comprising blocks with different Tg. This causes micro-phase separation in bulk with the formation of the reinforcing crystalline domains of one copolymer bonded to each other by the flexible chain of the second copolymer.

In essence, conventional adhesives comprising hetero atoms such as chlorine include, but are not limited to, insufficient strength / tear resistance, insufficient elongation / elasticity, non bio-compatibility, non food compatibility. Does have a wide variety of inherent disadvantages, leading to toxic residues upon combustion.

It is an object of the present invention to provide an adhesive that overcomes the disadvantages of prior art adhesives.

It is also an object of the present invention to provide an article containing an elastic adhesive.

It is also an object of the present invention to provide a method for producing the adhesive of the present invention.

Summary of the Invention

The present invention provides an article containing a first element and a second element bonded to the first element by an adhesive. The article is characterized in that the adhesive contains a polyolefinic homopolymer having an isotacticity of less than 60% of [mmmm] pentad concentration.

The present invention also provides a method of providing the above-mentioned adhesive coating comprising the step of applying an adhesive coating selected from the group of hot melting, spraying, powder melting, extrusion beads, liquids, solvent substrates, pressure sensitivity, and combinations thereof. .

The present invention provides an article containing a second element bonded to the first element by an elastic adhesive containing the first element and the polyolefin-based homopolymer.

As used herein, the term "polyolefinic homopolymer" refers to a polyolefin containing only one phase of a molecule, all of which exhibit a similar stereochemical configuration. For example, when the term is used, blends of hybrid arrangements and co-array polymers in which two phases are polymerized simultaneously are excluded. The term homopolymer includes copolymers in which all molecules exhibit similar stereochemical arrangements.

The polyolefin homopolymers of the invention have a structure of at least one C ₃ to C ₂₀ olefinic monomer and have a [mmmm] pentad concentration of less than 60%, preferably less than 50%, more preferably less than 40%, most preferably Preferably having an isotacticity of less than 30%, an [mmmm] pentad concentration of more than 8%, more preferably more than 10%, more preferably more than 12% and most preferably more than 15% It may contain a linear isotactic polymer having. Preferably, the polyolefin homopolymer is polypropylene.

Due to the homogeneous arrangement of homopolymers, the homogeneous distribution of stereoscopic errors in the polymer chains can be reduced compared to conventionally arranged polypropylenes in the art. The term "stereoscopic error" means a stereoscopic sequence characterized by [mrrm] pentad. In this case, the central monomer has a steric configuration opposite to the other four monomers of the pentad. Therefore, the [mrrm] pentad concentration of the polymer is the statistical probability of p ² (1-p) ² [where p = [m] and thus 1-p = [r] and p ⁴ = [mmmm]]. Exceeds. Preferably, the pentad concentration is [p (1-p)] ^q p (1-p) (q is 0.8, more preferably 0.6, even more preferably 0.4, even more preferably 0.2, most preferred Is 0.1).

For some embodiments of the homopolymers, particularly those where crystallinity is reduced by a single steric error, low content hybrid sequences have proven to be beneficial for the properties of the adhesives of the invention. Preferably, the [rmrm] pentad concentration is less than 6%, more preferably less than 5%, even more preferably less than 4%, even more preferably less than 3%, most preferably less than 2.5%.

For some embodiments of the homopolymers, particularly those where crystallinity is reduced by a single steric error, low ordered sequences have proven to be beneficial for the properties of the adhesives of the invention. Preferably, the [rrrr] pentad concentration is less than 6%, more preferably less than 5%, even more preferably less than 4%, even more preferably less than 3%, most preferably less than 2.5%.

Alternatively, the homopolymers of the present invention may comprise the sequence of the hybrid and isomeric blocks of the polymer.

Preferably, the average molecular weight Mw of the polymer is greater than 100000 g / mol, more preferably greater than 200000 g / mol, even more preferably greater than 250000 g / mol, even more preferably greater than 300000 g / mol, most preferred More than 350000 g / mol. When the elastic and tear resistance of the adhesive material is desired, a high molecular weight is particularly preferred.

In some applications, such as adhesion to polymers and mammalian tissues, it is preferred that the molecular weight is less than 200000 g / mol, more preferably less than 175000 g / mol, most preferably less than 15000 g / mol.

Glass temperature Tg is -50- + 30 degreeC. Preferably the glass temperature is below 10 ° C, more preferably below 5 ° C, even more preferably below 0 ° C, most preferably below -6 ° C. The melting temperature of the polymer is obtained by heating the sample to 150 ° C. and then cooling the polymer to −50 ° C.

Without being bound by the above theory, polyolefin-based polymers exhibit a semi-crystalline structure. The structure includes nano-scale-sized elastic amorphous regions reinforced with nano-crystalline self-arranged crystalline domains. Formation of the fragile macro-crystalline material from the polymer is accomplished by introducing defects into the polymer backbone. Isolated monomeric units with opposite steric arrangements have been used as defects, ie single steric error.

Suitable polymers and methods of making such polymers are described in PCT patent application EP99 / 02379, which is incorporated herein by reference. Suitable catalyst combinations for the preparation of such polymers are described in PCT patent application EP99 / 02378, incorporated herein by reference. Preferably, the process of PCT patent application EP99 / 02378 is carried out at a temperature below 30 ° C., more preferably below 25 ° C., even more preferably below 20 ° C. and most preferably below 15 ° C., resulting in a polymer. To increase the molecular weight. In order to increase the molecular weight, the polymerization is preferably carried out in a liquid monomer such as liquid propene. If it is desired to increase the molecular weight, the catalyst is preferably used in combination with the boron activator mentioned in the PCT patent application EP99 / 02378.

Other suitable polymers and methods of making such polymers are described in WO99 / 20664, which is incorporated herein by reference.

In the prior art, adhesive coatings, such as applying adhesives in forms including, but not limited to, hot melting, spraying, powder melting, extrusion beads, liquids, solvent substrates, pressure sensitivity, melt release fibers and combinations thereof A wide variety of suitable techniques are known for providing. The aforementioned methods of providing an adhesive coating all have certain advantages known to the skilled person. Therefore, the skilled person can select the appropriate method to provide the adhesive coating of the present invention according to the specific requirements of each application of the adhesive.

It has been found that the adhesive of the present invention can be attached to polished surfaces such as metal plates, PTFE coated surfaces, polymer surfaces, and the like. The adhesives of the invention are also suitable for attaching to mammalian tissues such as epithelial tissue.

Preferably, the adhesion between the two elements of the article of the invention is at least 5 Newtons per centimeter, more preferably at least 10 N / cm, even more preferably at least 20 N / cm, most preferably 40 N / cm It is adjusted more than. Of course, where lower peel forces are desired, the adhesion, for example the molecular weight, can be changed accordingly. Alternatively, the same peel force requirements apply when surfaces are attached to each other. Peel force is measured with respect to the specific surface on which they are used.

The adhesives of the present invention have also been found to emit relatively low odors even in the molten state. In particular, since the adhesive of the present invention can be prepared without using a solvent, in some embodiments of the present invention, the adhesive necessarily includes a solvent.

In some embodiments, particularly high molecular weight embodiments, it has been found that the adhesives of the invention exhibit increased temperature stability compared to adhesives in the art. This is due in part to the fact that, for the adhesives of the invention, homopolymers are used, and in part due to the high molecular weight of the homopolymers. Preferably, the adhesive material of the present invention has a melting point of at least 100 ° C, more preferably at least 110 ° C, more preferably at least 120 ° C, most preferably at least 130 ° C. The melting temperature of the polymer is obtained by heating the sample to 150 ° C. and then cooling the polymer to −50 ° C. If desired, higher melting points can be achieved by blending homopolymers with conventional isotactic polymers such as, for example, polypropylene.

Alternatively, in particular embodiments where the adhesive has a relatively low molecular weight, a melting point on the order of 50 ° C. can be achieved. Such a melting point can be used to inactivate the adhesive if desired. Heating the adhesive to its melting point causes the adhesive to flow, and thus can peel off even at very low peel forces.

It has been found that the adhesive of the present invention is not only extensible but also elastic. The stretchability of the adhesive versus its elastic behavior can be controlled by the stereoregularity of the homopolymers of the invention. It has been found that the adhesive material of the present invention stretches at least 500%, more preferably at least 1000%, even more preferably at least 1500% and most preferably at least 2000% of its original length without tearing. In addition, the adhesive material of the present invention is stretched to 500% of its original length and held for 1 minute and then recovered within 10 minutes to less than 300%, preferably less than 200%, most preferably less than 150% of its original length. . It has also been found that the adhesives of the invention exhibit a low compression tendency. The adhesive of the present invention is compressed to 50% of its original thickness for 1 minute and then within 10 minutes at least 60%, more preferably at least 70%, even more preferably at least 80%, even more preferably within 10 minutes of its original thickness. Recovery of at least 90%, most preferably at least 95%. The compressibility of the adhesives of the present invention can be controlled by either increasing the ordering regularity of the homopolymers or by blending a low stereoregular homopolymer with a conventional isotactic polymer such as polypropylene.

Without being bound by theory, the rheological properties of the adhesives of the present invention, namely storage or elastic modulus G 'and viscosity modulus G' ', respectively, exhibit their creep and their peeling / fast adhesion behavior during use. G 'and G' 'values at low frequencies (approximately 0.01 rad / s to 1 rad / s) and high frequencies (100 rad / s to 1000 rad / s) are thought to be related to the behavior of the adhesive during application and removal, respectively do. It is well known to measure G 'and G' 'over a wide range of frequencies, for example a Rheometric Scientific RS-5 flow meter can be used. The measurement of G 'and G' 'should be carried out at a preferred service temperature, i.e. at room temperature of 25 ° C for most applications or at 37 ° C for body related applications.

Preferably, the adhesive of the invention has a viscosity modulus G '' (1 rad / s) of less than 30000 Pa, more preferably of less than 25000 Pa, even more preferably of less than 20000 Pa, most preferably of less than 15000 Pa. Have Regardless of the theory, it is believed that these values of G '' (1 rad / s) are indicative of the adhesive not flowing when the adhesive is applied to the surface.

Preferably, the adhesive of the present invention has a viscosity modulus G '' (1 rad / s) of at least 500 Pa, more preferably at least 1000 Pa, even more preferably at least 1500 Pa, most preferably at least 2000 Pa. . Regardless of the theory, it is believed that these values of G '' (1 rad / s) are indicative of the adhesive which can confirm the topology of the surface on which the adhesive is applied.

Preferably, the adhesive of the present invention has a viscosity modulus G '' (100 rad / s) of less than 30000 Pa, more preferably less than 20000 Pa, even more preferably less than 15000 Pa, most preferably less than 10000 Pa. Have Without being bound by theory, it is believed that these values of G '' (100 rad / s) are indices that do not flow when the adhesive is removed from the surface.

Preferably, the adhesive of the present invention has a viscosity modulus G '' (100 rad / s) of at least 1000 Pa, more preferably at least 2000 Pa, even more preferably at least 3000 Pa, most preferably at least 4000 Pa. . Regardless of the theory, it is believed that the values of G '' (100 rad / s) are indicative of not breaking when the adhesive is removed from the surface.

Preferably, the adhesive of the present invention has a viscosity modulus G '(1 rad / s) of less than 30000 Pa, more preferably less than 25000 Pa, even more preferably less than 20000 Pa, most preferably less than 15000 Pa. . Preferably, the adhesives of the present invention have a viscosity modulus G '(1 rad / s) of at least 500 Pa, more preferably at least 1000 Pa, even more preferably at least 1500 Pa, most preferably at least 2000 Pa. Without being bound by the theory, it is believed that the values of G '(1 rad / s) are indicative of the adhesive retaining its elasticity when the adhesive is applied to the surface.

Preferably, the adhesive of the present invention has a viscosity modulus G '(100 rad / s) of less than 30000 Pa, more preferably less than 25000 Pa, even more preferably less than 20000 Pa, most preferably less than 15000 Pa. . Preferably, the adhesive of the present invention has a viscosity modulus G '(100 rad / s) of at least 2000 Pa, more preferably at least 3000 Pa, even more preferably at least 4000 Pa, most preferably at least 5000 Pa. Without being bound by the theory, it is believed that the values of G '(100 rad / s) are indicative of maintaining their elasticity when the adhesive is removed from the surface.

Preferably, the ratio of G '(1 rad / s) / G' '(1 rad / s) is in the range of 1 to 30. This is believed to be an indication of the flow behavior of the adhesive of the invention during application of the adhesive to the surface of the substrate.

Of course, where other values of G 'and G' 'are desired, the adhesive properties can be adjusted according to the limits given above.

The adhesives according to the invention can also be used as components in articles. Such articles include, but are not limited to, toys, furniture, clothing, shoes, sports equipment, composite components such as buildings, automobiles, home appliances, and the like. With respect to the particular advantages of the polymers used in the articles of the invention, it will be very apparent to those skilled in the art to apply and optionally modify the adhesives according to the invention as components in the above and similar articles.

The adhesives of the present invention are suitable for bonding non-sealing polyolefinic surfaces, for bonding and adhering to wood surfaces, for bonding and adhering to plastic glass or the like.

The adhesive is suitable for applications where the adhesive needs to be extensible, ie where the joining surfaces of the first element and the second element should be allowed only a small movement relative to each other. For example, the adhesive of the present invention may be used as binder resin for nonwoven web materials. The adhesive of the present invention will allow for further processing of the bonded nonwoven web material, for example mechanical activation such as ring rolling.

The adhesive of the present invention can be activated by electromagnetic waves, for example infrared, UV or visible light, ultrasonic waves and the like.

Additives known in the art can be added to the adhesives of the present invention. For example, the addition of talc is suitable for modifying adhesive properties.

Claims (7)

An article comprising a first element and a second element bonded to the first element by an adhesive, wherein the adhesive comprises molecules of a single phase in which the stereochemical arrangement of all molecules is similar, [mmmm] pentad concentration of greater than 10% An article comprising a polyolefin homopolymer having less than 40% isotacticity, less than 3% [rmrm] pentad concentration and less than 6% [rrrr] pentad concentration. The article of claim 1 wherein the homopolymer has a molecular weight of at least 100,000 g / mol. The article of claim 1, wherein the adhesive is extensible. The article of claim 2, wherein the adhesive is elastically expandable. The article of claim 1 wherein the homopolymer is polypropylene. The article of claim 1, wherein the adhesive is disposed as a component. A method of providing an adhesive coating comprising applying an adhesive coating selected from the group consisting of hot melting, spraying, powder melting, extrusion beads, liquids, solvent substrates, pressure sensitivity, and combinations thereof, wherein the adhesive coating comprises Single phase molecules with similar stereochemical configuration, [mmmm] pentad concentrations greater than 10% to less than 40% homozygosity, <rmrm] pentad concentrations less than 3% and [rrrr] pentads less than 6% A method comprising a polyolefin homopolymer having a concentration.