KR102341982B1 - Hot melt adhesive that can be processed by high-speed process - Google Patents

Abstract

The present invention discloses a novel hot melt adhesive formulation with improved processability that can be easily processed even by high-speed processes, particularly spraying or fiberizing processes. The hot melt adhesive formulation is a low-viscosity, as its main polymer component, in two successive and separate reaction steps, wherein the first polymer (Polymer A) of the compositionally bimodal polymer composition is isotactic with the other olefins. butene-1 copolymer or isotactic butene-1 homopolymer, whereas the second polymer (polymer B) is qualitatively and/or quantitatively butene-1 isotactic with other olefins having a chemical composition distinctly different from copolymer A in the step of being a copolymer, comprising at least one isotactic metallocene butene-1 polymer composition having a substantially bimodal composition obtained directly upon polymerization, wherein the hot melt adhesive further comprises a viscosity modifier that is not solid at room temperature. . The hot melt adhesive formulations according to the invention are suitable for use in articles of various types of use, in particular in the manufacture of absorbent hygiene articles.

Description

Hot melt adhesive that can be processed by high-speed process

The present invention provides novel and optimal processability, even for processes at high production line speeds and high or very high strain rates (known in technical terms as “shear rates”), which occur especially in spraying and fiberizing application processes. A novel hot melt adhesive formulation is disclosed.

The hot melt adhesive of the present invention, as its main polymer component, is a substantially bimodal composition having low viscosity (and therefore relatively low average molecular weight), and obtained directly upon polymerization in two successive and separate reaction processes, wherein the composition Thus, the first polymer (polymer A) of the bimodal polymer composition is an isotactic butene-1 homopolymer or isotactic butene-1 copolymer with another olefin, whereas the second polymer (polymer B) is qualitatively and quantitatively at least one isotactic metallocene butene-1 polymer composition having a bimodal composition which is an isotactic copolymer of butene-1 and another olefin having a chemical composition distinctly different from A; It further comprises a viscosity modifier that is not solid at room temperature.

In addition, its novel processability is surprisingly improved even for application processes at very high line speeds and at high or very high shear rates, mainly for spraying or fiberizing applications (polybutene-1 of different grades than used herein). Compared to other hot melt adhesives comprising

- exhibit surprisingly low viscosity and very low elastic values in the molten state, which, in addition to justifying optimal processability at high and high shear rates - as can be seen below - at relatively low temperatures It can be applied on substrates that are thermosensitive, for example plastic films with low heat deflection temperature/melting point and/or especially thin substrates such as plastic films or nonwovens with low basis weight.

- Even immediately after curing in the molten state, it exhibits very good properties of high cohesiveness (in the case of hot melt adhesives, a characteristic generally incompatible with low viscosity in the molten state) and strong adhesion.

- After curing in the molten state, the polybutene-1 chain undergoes a controllable slow crystallization delayed with time at the working temperature in the solid state (usually room temperature), which already exhibits good initial adhesion, cohesiveness and physical properties. improved more significantly. The slow crystallization phenomenon at room temperature allows polybutene-1 crystals to be particularly robust and controllably formed in optimal amounts of 'complete' morphologically, e.g. elongation at break and rheological parameters Tan Delta (Tan Delta). The major physical and rheological properties of hot melt compositions, such as a significant increase in their hardness (e.g., as measured according to test method ASTM D1321-04), modulus of elasticity (G'), and tensile strength at break, concomitantly with a significant decrease in Substantial changes in enemy parameters can be detected.

In addition, another important effect on the adhesive properties of the hot melt formulation of the present invention resulting from the slow crystallization has a significant effect on the change over time of the tackiness of the formulation itself.

On the other hand, immediately after curing from the melt (i.e., see below for the definition of “zero hour”), the adhesive formulations according to the invention are soft and very tacky adhesives at room temperature and thus optimal adhesion with a wide range of substrates. It creates a bond immediately and then delays subsequent crystallization to radically change their rheological, physical and adhesive properties (as will be described in more detail below), making it robust against the initial surface tackiness of the adhesive formulations of the present invention. affect

As already mentioned, the significantly high tack at 0 hours decreases over time (i.e. with the progress of crystallization) to surprisingly lower values, since it only requires the immediate formation of a good adhesive bond. It drops to zero and thus does not exhibit any residual tack in the final state, providing an adhesive that can be defined as completely "tack free".

This characteristic of the adhesive, in which the adhesiveness changes dramatically only by simple short standing at room temperature, some adhesives contained in the product accidentally come into contact with the user's skin during use, causing serious inconvenience and possible disadvantages, or packaging of the product In particular in all areas of use (e.g. For hygiene absorbent articles, for example), a very important and valuable property is that any residual tackiness no longer appears.

The slow crystallization of the hot melt adhesive formulation according to the present invention in the solid state and at room temperature, which is delayed with time, can usually begin to be detected about 2 hours after the adhesive has solidified in the molten state, while for example Other hot melt adhesives of different polyolefin types, such as polyethylene, polypropylene, copolymers thereof, etc., can reach, after solidification, substantially immediately the final level of crystallinity which can be reached according to the respective molecular structure and composition. In contrast, crystallization of the hot melt adhesive of the present invention, which is delayed over time in the solid state, is generally completed within a few days, such as from about 1 day to about 7 days, usually about 5 days.

- The fact that the material is initially cohesive but at the same time soft in the solid state immediately after solidification from the molten state, and the high value of the rheological parameter tan delta allows the immediate formation of a surprisingly strong adhesive bond. Indeed, as will be apparent to one skilled in the art, this property maximizes the strength of the adhesive bond as it allows for very close contact between the adhesive and the substrate being bonded and good wettability therebetween.

- Said characteristic rheological property of the hot melt adhesive according to the invention, the fairly long "open time" (see below for its definition and measurement), makes it possible to optimally and very easily control both the bonding process with substrates of various properties. do. In addition, tan delta, a rheological parameter with initially high values, allows the hot melt adhesive according to the present invention to continue to "flow" into very close contact with the substrate even in the solid state, whether the substrate is porous, fibrous or perforated. In some cases-particularly between the fibers or into the interior of the voids between the pores of the substrate, this situation further strengthens the adhesion not only by adhesive bonding but also by the formation of physical interlocking between the adhesive and the substrate. Owing to this peculiar behavior, the hot melt adhesives according to the invention are particularly suitably used, for example, on porous or fibrous substrates, which are very often used in hygiene absorbent articles, or on perforated films having a two- or three-dimensional structure. .

However, the high values of tan delta mentioned above can be detrimental because if the adhesive is held constant too high for too long, the adhesive will continue to flow into the applied substrate or into the article. In this way, the adhesive strength value may be greatly reduced due to the “physical loss” of the adhesive itself, since the adhesive may migrate to a completely different place in an area different from the surface to which it is to be adhered; Alternatively, the adhesive may be “resurfaced” on the opposite side of the fibrous or perforated substrate, in this way a so-called negative phenomenon known as “bleed-through” occurs to the exterior of the fibrous or perforated substrate. Adhesive, which migrates primarily through the holes to the outer surface of the substrate, may cause the face to adhere improperly to other parts of the article contained therein and to parts it should not adhere, or otherwise adhere unpleasantly to the user's skin.

Without wishing to be bound by any theory, this novel and surprising combination of positive and highly desirable properties for hot melt adhesives (low viscosity in the molten state and excellent instantaneous cohesion in the solid state, even before the time-delayed crystallization phenomenon even begins) As coexisting, in some cases the combination of contradictory properties between them) is the compositional structure of the novel isotactic metallocene butene-1 polymer composition of low viscosity and the bimodal composition obtained directly upon polymerization as used herein. and novel and unusual molecules.

In particular, as will be more clearly described below, it seems reasonable to assume that the innovative and surprising properties of the hot melt adhesive composition of the present invention are primarily due to the following unique properties of the polymer polybutene-1 composition:

- a compositionally bimodal structure with a very narrow distribution around the two centers of modality; In particular, this means that fractions at both low and very low molecular weights as well as high and very high molecular weights are substantially free; In polybutene-1 synthesized by the synthesis process of

- a sufficiently low average molecular weight to provide the desired low viscosity in the molten state, without going through any process of destroying the molecules by peroxides since it was necessary to use spherical polybutene-1 synthesized with Ziegler-Natta catalyst It is already obtained in the synthesis reactor in a very controlled manner.

- In addition, low elasticity in melting due to the molecular morphology described above. This property is related to the low viscosity and justifies the unexpected good processability, especially for processes at high and high shear rates, such as spraying and fiberizing.

- the existence of two centers of compositionally modality, operating in a novel and highly advantageous manner in the adhesion process. For example, the fraction of the polymer clustered around the center of the modality with the highest curing temperature will solidify earlier to immediately provide optimal cohesion, while the remaining fraction of the polymer composition will continue to flow on the substrate and wet the substrate. It is reasonable to assume that the strength of the resulting adhesive bond is optimized by

Accordingly, as may be better explained in greater detail on the following pages, the main scope of the present invention are the low viscosity, bimodal compositions obtained directly upon polymerization as used herein, and the novel isotactic metallocene butenes described above. -1 formulating the polymer composition in the most suitable way as a hot melt adhesive formulation, which method combines the unique properties of the novel special polymer composition with the highest adhesive properties, rheological properties, which are generally required for selective quality of hot melt adhesives; By combining with the physical and processing properties, the final adhesive formulation of the present invention fully retains the innovative and unique properties of the novel polymer composition, particularly with regard to delayed time-dependent and effective crystallization occurring in the solid state and at room temperature. .

The hot melt adhesive compositions according to the present invention have their characteristic properties: very low viscosity in the molten state; low elasticity in the molten state; Excellent processability by high-speed spraying or fiberization; The combination of strong cohesion and strong immediate adhesion; variable long open times in any case; crystallization in the solid state, which is delayed with time, which more significantly increases adhesion time and physical properties; Due to the very low or completely non-existent residual final tack, it is particularly suitable for use in the manufacture of absorbent hygiene products in the application of various types of articles hitherto commonly required in the use of other adhesives. For example, without limiting the possible uses for other applications in this way, the hot melt adhesive composition according to the present invention can be used in absorbent hygiene products as general adhesives such as: adhesives for the manufacture of all articles; adhesives for bonding elastic components (such as threads, strips, elastic films or panels); adhesives for bonding of perforated films, which may have both two-dimensional or three-dimensional structures; Adhesives, etc. to strengthen and ensure the integrity of the absorbent core of absorbent hygiene products even when in use.

Rule

The expression "comprises" or "comprising" specifies the presence of what follows the term in the text, but does not include other components or features, such as elements, steps, components, known in the art or described herein. It is used herein as an open-ended term that does not exclude the presence of any of the disclosed ones.

The expression "not solid" is used herein to mean the physical aspect of a particular compound or component or component or mixture thereof, wherein the physical aspect is a physical aspect of a compound or component or component or mixture thereof, which is not in its fixed shape, even if it has a definite volume. It takes the shape of the containing container. Even if they are viscous enough to be temporarily shaped into any three-dimensional shape, after standing without external stress, they deform permanently, independently of their own weight, and flow spontaneously very quickly (usually several In a given period of time varying from seconds to about 1 day), the initial shape is lost, and takes the shape of the container containing them (if they are not already full to the end) or the shape of the solid surface on which they rest. Thus, this provision can be defined not only as "liquid (at both high and low viscosity)" according to the ordinary meaning of this adjective, but also as "soft", "grassy", "jelly" in a common language, for example. It further includes all ingredients defined as "like", "fluid", "sticky", "semi-solid", and the like. Another way to define in rheological terms what is meant in the present invention when a particular compound or ingredient or ingredient or mixture thereof is said to be “not solid” at room temperature is, in rheology, the viscosity modulus ( According to the rheological rule, G") is greater than the modulus of elasticity (G'), or the equivalent according to the rule that the tan delta is greater than 1, i.e., a material that is not "solid" at a temperature of usually 23°C is "rheologically liquid" " can be defined as

"room temperature" means a temperature of 23° C. unless otherwise specified; Also, "indoor conditions" means an environmental condition of controlled temperature and relative humidity of 23 DEG C and 50% relative humidity.

"Absorbent hygiene products" means adult incontinence diapers and underwear, baby diapers and bibs, training pants, infant care wipes, women's menstrual pads, interlabial pads, panty liners, pessaries, sanitary napkins, tampons and tampon applicators, wound dressing products , devices and/or methods directed to disposable absorbent and non-absorbent articles, including absorbent care mats, detergent wipes, and the like.

By "perforated film" is meant a film consisting of a plastic component, such as polyethylene, which is usually perforated with a plurality of apertures, which may have both two-dimensional or three-dimensional structures, and which are commonly used as components of absorbent hygiene products. Hole sizes range from a few hundred microns to about a millimeter.

By "fibrous substrate" is meant an article having an essentially flat structure formed by natural or synthetic fibers or mixtures thereof in the form of woven and non-woven fabrics equally used as components in absorbent hygiene products.

By "polydispersity" or "molecular weight distribution index" or "PDI" is meant a measure of the dispersion of the molecular weight of a particular polymer. It is defined as the ratio between the weight average molecular weight (Mw) and the number average molecular weight (Mn): PDI=Mw/Mn. The larger the value of PDI, the wider the distribution curve of molecular weight, and vice versa. Mw, Mn, and their ratio Mw/Mn=PDI can be measured, for example, by gel permeation chromatography (GPC).

The "open time" of an adhesive, particularly in the case of a hot melt adhesive, means that after application of the melt onto a first substrate, the adhesive with a second substrate in contact with the first substrate under moderate pressure will form an adhesive bond strong enough for its intended use. possible time interval. It is clear that an open time that is too short can make the application of the adhesive and the formation of a sufficiently strong bond difficult. The open time of the hot melt adhesive may be measured according to test method ASTM D 4497-94, and in some cases may be partially modified in an appropriate manner (see below for a more detailed description).

"Ring and ball softening point" means the softening temperature of a component measured according to ASTM D 36-95 method.

prior art

Isotactic homopolymers and copolymers of polybutene-1 (derived from butene-1 and other olefins such as ethylene) were initially manufactured industrially and marketed by companies such as Huls, Mobil, Witco, For a long time, mainly Shell, since 1977, has been the world's main supplier and continues to be manufactured today by LyondellBasell.

All products of "spherical" polybutene-1 were prepared using a Ziegler-Natta type of catalyst.

In recent years, LyondellBasell has produced both a substantially "single" or "monomodal" composition having a substantially bimodal composition obtained directly upon polymerization in two successive and separate reaction steps, or a low viscosity isotactic butene-1 polymer composition. A novel polybutene-1 synthesized with a metallocene catalyst having These latest novel polymer compositions are described in detail in two patent applications, Basell Poliolefine Italia EP 16178432.7 and EP 16178433.5, the contents of which are incorporated herein by reference.

Without being strictly bound by an analysis of the differences between the two catalyst technologies and the characteristics of the manufacturing process involved, the metallocene technology is very different and improved compared to those obtainable by conventional Ziegler-Natta type catalysts. It is well known that polymers with specific molecular properties can be synthesized. In particular, Ziegler-Natta catalysts, which are usually "multisite", are mixtures of different polymer chains - very wide "variance" or "dispersion" or "distribution" - both differing in molecular weight as well as in chemical composition (in the case of copolymers). It can be emphasized that in any case having "

In this way, the synthesis produces polymers with a very broad distribution/dispersion in both composition and molecular weight.

In contrast, it is well known that the use of metallocene catalysts in a conventional "single" catalytic site can yield very narrow distributions of both composition and molecular weight; In addition, metallocene catalysts allow much more precise control of the molecular weight to be obtained, thus making it possible, for example, to prepare especially low molecular weight polymers, which are particularly suitable for low viscosity hot melt adhesive formulations, already upon polymerization. .

This is not possible with polybutene-1 synthesized by Ziegler-Natta catalyst. Since the spherical polymer has a characteristic that not only has a very high molecular weight but also has more difficult processability, it is usually suitable for use in low-speed or very low-speed production processes such as extrusion of pipes.

These high viscosities are removed by melting and in order to at least partially compensate for their poor processability in high-speed processing, in general all these Ziegler-Natta types of polybutene-1s are treated with an amount of organic peroxide and/or Or it is added and marketed.

Thus, in all the examples cited in the prior art using Ziegler-Natta type polybutene-1, the peroxide is clearly added to these polymers by the supplier - for example Shell, etc. - before being put on the market. Even if not mentioned, there is thermal molecular destruction of polymers by peroxides.

During processing of these polybutene-1s at high temperature and molten state, these peroxides cause destruction and reduction of the average molecular weight of these polybutene-1s by a radical mechanism, which, for example, causes the initial Due to the breakage of long polybutene-1 chains and the "lubricating" of the additional amount of low molecular weight chains produced during the radical process of fragmentation, it lowers the melt viscosity and at least somewhat improves the processability at low speed processes.

However, it is clear to those skilled in the art of polymer science that the destruction of molecular weight via a thermal mechanism by the peroxide is a chaotic, random process, the end result of which is not fully controlled and uncontrollable.

As a first result, in any case, the practicality of maintaining significantly higher minimum melt viscosities achievable by the above technique (e.g. viscosity for degrading degraded polymers - see below for definition of MFR) In addition to finding thresholds, this chaotic and uncontrollable breakage of the long initiating chain of polybutene-1 is dependent on its structure (eg, presence and absence and amount of branched side chains), its length (molecular weight) and its composition. It is clear that this (in the case of copolymers) produces new chains that are entirely random and uncontrollable, and that their chemical and physico-chemical properties give the final polymer with high variance and unpredictability.

That is, when starting from the same high viscosity polybutene-1 as the Ziegler-Natta catalyst, and even when the same test conditions are maintained for the various examples of molecular weight breakdown (i.e., the same type and amount of breaking peroxide) to finally obtain a decomposed final product having approximately the same average overall melt viscosity, i.e. the same overall MFR), and in practice in each example, in the thermal destruction process In terms of the structure, length and composition (in the case of copolymers) of the newly generated chains produced, the polymers produced by random processes are often highly variable and "different".

The high variability and uncontrollability/unpredictability of the molecular properties of the final polymer product resulting from these processes (i.e., even if it is necessary to obtain approximately the same final overall MFR) are highly undesirable and potentially negative properties, especially for peroxides. This is the case when the polybutene-1 decomposed by the above is used as a component of a hot melt adhesive.

Indeed, it will be appreciated by those skilled in the art that the molecular properties of the polymers used to formulate hot melt adhesives have a very strong influence on all key properties of the adhesive (adhesion, cohesion, melt elasticity and thus good or poor processability, especially in high-speed processes, etc.) It is well known.

Also, for certain hot melt formulations that may approximate the "limit criteria" of the adhesive or the essential properties of the adhesive, a possible change in the molecular properties of the base polymer, even at apparently very small sizes, is a hot melt adhesive comprising the polymer. It is well known that in the main application properties (adhesion, agglomeration, process-related, etc.) of

Also, in the case discussed herein, that is, in the case of a hot melt adhesive comprising polybutene-1 synthesized with a Ziegler-Natta catalyst which initially lowers an unacceptably high average viscosity by heat treatment with a peroxide, the final adhesive In addition to the completely unpredictable (even potentially very negative) effects of these treatments on the main properties of

As mentioned above, a fundamental and substantially intrinsic property of hot melt adhesives comprising polybutene-1 is that they exhibit crystallization delayed over time, which, if this can occur under optimally controllable conditions, already has good initial adhesion, cohesion. , and the fact that it can lead to further and significant improvements in the physical properties of the adhesive will be better explained below.

As is well known to those skilled in the art of polymer science, it can be said that the crystallization of the polymer matrix is taking place in an easier way, i.e. the more crystals formed, the more "perfect" in quality, the better the structure, composition, molecular weight (not too high). preferred), etc., the molecular properties of the polymer chains are more "similar" to each other.

Therefore, molecular breaking by peroxide of polybutene-1 synthesized with the Ziegler-Natta catalyst in the above process is the main effect of the structure, length, and composition of the molecular chain of polybutene-1 (of the copolymer). It is clear that, after their treatment, the fact that broadening the amount of variability of the

In any case, returning to the prior art teachings regarding the use of polybutene-1 in the formulation of hot melt adhesives, the major conventional supplier of polybutene-1 itself, i.e. Shell, in hot melt adhesive formulations, Ziegler- In several patents filed for possible uses of homopolymers or copolymers of polybutene-1 obtained from Nata synthesis, such as US Pat. No. 4,568,713, the average molecular weight of these polymers prior to synthesis into a hot melt adhesive composition using a peroxide Thus, it teaches that it is indispensable to destroy in advance by heat treatment. As already mentioned, for this reason, all of these polybutene-1 synthesized by Ziegler-Natta catalyst are treated by adding an appropriate amount of peroxide.

For example, the case of homopolymers and copolymers of polybutene-1, such as homopolymer DP 0800 or copolymers butene-1/ethylene DP 8510 and DP 8910, marketed by Shell at the time cited in U.S. Patent No. 6,218,457 have.

Despite the destruction of molecular weight caused by the peroxides present in these polymers, upon heat treatment for the production of hot melt adhesives, the final melt viscosity of the hot melt adhesive composition mentioned in the examples of US Pat. No. 6,218,457 is very high. In fact, it varies from a minimum of 7,300 mPa.s to a maximum of 31,200 mPa.s when measured at 163°C (325°F).

As will be clear to those skilled in the art of preparing and processing hot melt adhesives, the above-mentioned hot melt adhesives have high or very high melt viscosities and are therefore unprocessable in high speed application processes, especially with high shear rates such as spraying or fiberizing, or Almost impossible to machine in very high application processes.

Also, with respect to the prior art taught by U.S. Patent No. 6,218,457, in some disclosed embodiments the hot melt adhesive contains significantly greater amounts of another polymer, particularly APAO (amorphous-poly-alpha-olefin) than polybutene-1. in an amount; In this way, the formulations disclosed in these examples emphasize that APAO-based formulations modified with lower amounts of polybutene-1 should be considered more suitable and vice versa not. The presence of a different polymer, such as APAO, in major amounts relative to polybutene-1 is essential to improve the adhesion, cohesion and processability of the adhesive to acceptable levels, which is why Ziegler-Natta polybutene-1 is the only polymer in the formulation. If so, the quality may be unsatisfactory in and of itself. In addition, for the following crystallization delayed with time of polybutene-1, in any case, it is a positive and desirable effect because it can further increase the adhesive force and cohesive force of the disclosed hot melt adhesive, and polybutene-1 and a large amount of other polymers , in particular the presence of an amorphous polymer such as APAO in a predominant amount relative to polybutene-1 “dilutes” the crystalline polymer polybutene-1 by the presence of a polymer such as APAO in a predominant amount, preventing crystallization, and its Considering the fact that itself is amorphous and cannot be crystallized, it can only have a negative effect on the crystallization, both in kinetic and quantitative terms.

In contrast, in another example of U.S. Patent No. 6,218,457, in which no major amount of APAO is present, a significant amount of polyisomer is used to lower the viscosity at least to a non-excessive level to allow processing of the formulation, and also to improve adhesion. The addition of butylene plasticizer (PIB, a chemically and structurally completely different substance) appears to be indispensable.

However, this addition of said plasticizer appears to have a very negative effect on the properties of agglomeration and crystallization of the disclosed formulations comprising polybutene-1 of the Ziegler-Natta type, and the inventors simultaneously Crystalline wax, a component acting as a well-known fact as an initiator and accelerator for the crystallization of

Nevertheless, those skilled in the art of hot melt adhesives know that the addition of such a large amount of wax impairs the adhesive properties of the hot melt adhesive, lowers its tackiness, and greatly shortens its open time (as short as about a few seconds or less than 1 second). It is well known that it tends to harden or weaken the adhesive composition excessively. Despite significant additions of plasticizers and waxes, both components having very low viscosities by themselves, the viscosities of the examples without APAO as disclosed in US Pat. No. 6,218,457 continue to be exceptionally high (at 163°C (325°F) 10,375 mPa.s to 10,625 mPa.s), which makes it very difficult to process these hot melt adhesives in the molten state, and makes it impossible to apply them to processes at high and high shear rates such as spraying and fiberizing. It should be noted

Other prior art patents, such as, for example, US Pat. No. 5,786,418, in the disclosed examples, provide a copolymer of polybutene-1 of a hot melt adhesive (in all cases, a spherical polymer, i.e. by means of a Ziegler-Natta catalyst). synthesized polymer), for example at 325°F (163°C), with a rather low viscosity and without the major addition of other polymers, formulating to have a viscosity of 1,500-5,500 mPa·s. However, this formulation strategy also appears to negatively affect the adhesion and cohesive properties of the formulations disclosed in U.S. Pat. I think we need to have a very short "open time" of about 0.5 seconds; This means that usually 0.5 seconds or less can elapse between the application of the adhesive of the melt on the first substrate and the contact of the second substrate to be bonded if it is desired to obtain a sufficiently strong adhesion.

Obviously, this exceptionally short open time is a strong limitation of the usefulness of the present invention, since it affects and severely limits the possibility that the composition can be used in other processes and in other applications at low rates, and the application of adhesives and A time interval of up to 30 seconds or less between the adhesion of the second substrate is a very difficult operating situation and in some cases not achievable.

All other prior art patents use polybutene-1 synthesized with a Ziegler-Natta catalyst, and the addition of a significant amount of crystalline material acting as a crystallization initiator/nucleating agent such as a crystal nucleating agent, a crystalline wax or a crystalline solid plasticizer. attempts to maximize the ability of polybutene-1 to crystallize in the solid state by

In some cases, the prior art is, for example, as taught in U.S. Patent No. 8,454,792, polybutene-1 to obtain temporary adhesives, ie hot melt adhesives that completely and soon lose their initial adhesive properties and transition from an adhered state to a non-adhesive state. "Uncontrolled" massive and rapid crystallization of Alternatively, as claimed in U.S. Patent No. 5,256,717, hot melt adhesives that become too hard and brittle due to excessive crystallization in which the substrates bonded with these adhesives are easily separated from each other due to the cohesive failure of the adhesive itself.

U.S. Pat. No. 8,454,792 uses high levels of crystalline wax, whereas U.S. Pat. No. 5,256,717 uses spherical polybutene-1s such as polymers DP 8910 or PB 0800 M to promote particularly massive and rapid crystallization. Using plasticizers, the crystalline structure of these additives in all cases acts as an accelerator and nucleating agent for the crystallization of polybutene-1, increasing the final level of crystallinity and making its mobility faster.

In summary, based on homopolymers and/or copolymers of isotactic polybutene-1 synthesized by Ziegler-Natta catalysts, as taught by the prior art, a set of all features highly desirable for hot melt adhesives. , for example low viscosity and low elasticity in the melt state; high initial cohesive strength and high initial adhesive strength which can impede and impair the subsequent crystallization of polybutene-1 without the addition of large amounts of other polymers; initial cohesive strength that occurs in a slow and controllable manner and increases more markedly with time, particularly due to crystallization of the ordered and "rigid" solid state; good processability even in high-speed processes and especially in processes such as spraying and fiberizing; Adjustable adhesive open times, long enough to allow for easy and strong bonding in a wide variety of different processes; final tackiness of very low or completely absent residues; It is impossible to formulate a hot melt adhesive that simultaneously has rheological properties that change significantly over time in the service temperature (typically room temperature) and in the solid state, but since crystallization proceeds immediately after the adhesive solidifies, the modulus of elasticity (G') is particularly advantageous for bonding of porous or fibrous substrates and perforated films having both two-dimensional or three-dimensional structures, with a significant increase in In any case, it can continue to flow into it, penetrates physically, and enhances strong physical interlocking with a substrate or the like by adding purely adhesive strength.

The problem to be solved by the present invention is that it can be processed very well even in processes at high and very high speeds, at the same time exhibiting low viscosity and low application temperature in the melt state, but high in the solid state even immediately after solidification from the melt. Formulating a hot melt adhesive that bonds with cohesiveness and high adhesion, these properties increasing over time, overcoming the deficiencies of the existing prior art and allowing it to remain at its best in the final hot melt adhesive formulation, Included herein are the unique properties of the novel metallocene butene-1 polymer compositions having bimodal compositions, particularly those relating to particularly effective crystallization delayed over time in the solid state and at room temperature.

The above problems are addressed by an adhesive composition having the properties of claim 1 , a bonding structure having the properties of claim 42 , an article having the properties of claim 44 , and an article having the properties of claim 48 . The other subclaims disclose preferred embodiments.

Crystallization of the hot melt adhesive according to the present invention is delayed with time.

As mentioned, the hot melt adhesive according to the present invention is a low viscosity isotactic metallocene bimodal polybutene-1 composition included in the hot melt adhesive in the solid state and at the temperature of use (generally consistent with room temperature). indicates crystallization. This controllable and delayed crystallization over time further significantly improves the already good initial adhesion, cohesiveness and physical properties of these hot melt adhesives.

Isotactic polybutene-1 is generally known in the art for its ability to crystallize slowly in the solid state in a unique way that is completely different from the behavior of all other polyolefins, both in its homopolymers and copolymers. This particular property was discovered after a test sample of this polymer was first synthesized in 1954 by the discoverer, Nobel laureate Giulio Natta.

All other crystallizable polyolefins, such as, for example polyethylene or isotactic polypropylene, when solidified from a melt, in a very rapid and often substantially instantaneous manner, crystallization which can be achieved depending on the final crystal structure and their specific molecular morphology. , but the isotactic polybutene-1 crystallizes in a completely different way.

Without starting a detailed discussion of the above mechanism, one of the unique molecular structures of isotactic polybutene-1 chains formed by a relatively long, sterically bulky and compact series of side groups C2 is located close to the other, e.g. For example, it can be thought of as significantly slowing the formation of crystalline regions compared to what occurs in polypropylene or polyethylene.

However, the highly ordered structure as well as the shape of the helical space that the chains of polybutene-1 tend to assume - after a period of time - form a significantly larger crystalline fraction with this polymer compared to other semi-crystalline polyolefins and , resulting in the final physical properties of polybutene-1 that are significantly more robust.

This process of slower, larger and more robust growth in isotactic polybutene-1 in the crystalline structure is further facilitated by the polymorphism of this polymer and has up to three different crystalline forms.

One of these (called Form III) is formed only from solution and is not the subject of the present invention. The second crystal form (called Form II, which has a square structure) is formed first by solidification from the melt, as in the present case.

Both forms of isotactic polybutene-1 are thermodynamically unstable and slowly transform into a stable hexagonal crystal form (called Form I) with a higher melting point and physical properties.

Thus, the phenomenon that can be referred to as "delayed crystallization with time" from now on is actually a square structure that is formed after solidification from the melt initially, in addition to the slow growth of new crystals, and converts the thermally unstable Form II crystals to the more rigid hexagonal Form I crystals. It involves slowly transforming into crystals.

Considering this phenomenon in general terms, this specific crystallization delayed with time is present in all isotactic polybutene-1s regardless of the synthesis process.

However, novel isotactic metallocene butenes having monomodal and high viscosity spherical homopolymers and copolymers of isotactic polybutene-1 synthesized with Ziegler-Natta catalysts and low viscosity substantially bimodal compositions- The fundamental differences at the molecular level that exist between 1 polymer compositions also lead to fundamental differences in how crystallization of polybutene-1 chains can occur, both qualitatively and quantitatively, even when all other ambient conditions remain the same. .

Recalling again, the spherical polybutene-1 synthesized with the Ziegler-Natta catalyst has a very high melt viscosity, i.e. a very high average molecular weight, and a very broad molecular weight distribution/high polydispersity (usually greater than 4 and in some cases 6 excess), ie they are characterized by high and very high molecular weights, and by the presence of significant fractions at both low and very low molecular weights.

In contrast, the novel isotactic metallocene butene-1 polymer compositions of the present invention are low-viscosity, substantially bimodal compositions that control much lower average molecular weights, for example from about 30,000 to about 100,000; In particular, both very high molecular weight fractions and very low molecular weight fractions are substantially free in these novel polymer compositions. This is clearly indicated by the small polydispersity, considering the composite of the bimodal polymer composition formed by the two polymers A) and B) (the polymer composition and the polymer will be described in detail below), which is significantly less than 4 small; On the other hand, in the case of two single constituent polymers, it is usually 2.5 or less.

Without wishing to be bound by any theory, for example, in the polymer composition used in the present invention the substantial absence of a large fraction of chains having very low molecular weight and each small chain capable of acting as a nucleating agent/crystallization initiator is, It can be considered that the crystallization is activated so that it is not controlled too quickly, preventing the possibility of forming an excess of crystals that may destroy the adhesive properties—as shown in some examples of the prior art.

Alternatively, the absence of a large fraction of very low molecular weight is itself evident to the person skilled in the art of polymer science, and thus the absence of a large number of possible crystallization nuclei/centers is - in the hot melt adhesive of the present invention - in contrast to the Ziegler-Natta The final physical properties of the hot melt adhesives disclosed in the present invention form on average larger, stronger, and morphologically "perfect" crystals compared to what would happen with similar hot melt adhesives based on catalytically synthesized spherical polybutene-1. Both properties and adhesion properties are significantly improved.

Thus, the presence of substantially small amounts of "spontaneous crystallization centers", which consist essentially of the chains having the lowest molecular weight, also result in crystallization of the hot melt adhesives of the present invention occurring in an averagely slower manner, resulting in two major positive results. has

In one aspect, this slower and controlled crystallization tends to lengthen the open time of the adhesives of the present invention, usually at least 10 minutes, preferably at least 30 minutes, more preferably at least 60 minutes, resulting in a longer open time of the adhesives of the present invention. The adhesive has the advantage of being easy to use in a variety of different applications and processes.

In another aspect, as is well known to those skilled in the art of polymer science, slow crystallization promotes the formation of morphologically stronger and "perfect" crystals, thereby improving the adhesive strength and physical strength properties of the hot melt adhesives of the present invention. further improve

Also, in contrast, although present in large amounts in polybutene-1 synthesized with Ziegler-Natta catalyst, almost all of the high molecular weight and very high molecular weight fractions in the adhesive formulation of the present invention are also obtainable crystals It is reasonable to think that it leads to positive results important for the quality and quantification of the award.

For example, it is well known in the art that the final level of crystallinity obtainable from a polymer and the "quality" of the crystal are inversely proportional to the average molecular weight; Such properties decrease/deteriorate with increasing average molecular weight, which is clearly described, for example, in the book "Crystallization of Polymers", edited by Marcele Dosiere, on pages 26 to 26, which is incorporated herein by reference.

In addition, the narrow distribution in the normal pure compositional aspect (other than the molecular weight aspect) of the novel isotactic metallocene bimodal butene-1 polymer composition used in the present invention is that of the crystals formed in the adhesive formulation of the present invention. It is worth noting that it can lead to positive results both qualitatively and quantitatively.

Indeed, polymer chains that are similar in composition and structure as well as average length (molecular weight) to each other are significantly larger, more homogeneous, and significantly larger in solid state and at room temperature compared to what can occur with isotactic polybutene-1 of the Ziegler-Natta type. , it is quite reasonable to think that it enables slow crystallization to form "perfect", harder crystals, and thus substantially improves all the adhesion and physical properties of the hot melt itself.

The slow crystallization at room temperature of the hot melt adhesive formulation according to the present invention results in significant changes in the adhesive, physical and rheological properties of the hot melt adhesive itself; These properties, which are already good immediately after the hot melt adhesive has solidified in the molten state, are further improved with the progress of crystallization, which is completed within a few days, explicitly from about 1 to about 7 days, usually within about 5 days.

Unless otherwise specified, all properties mentioned below for materials left at room temperature are taken at 23° C. on samples stored for 5 days in a room conditioned at 23° C. and 50% relative humidity.

In contrast, the initial properties, commonly referred to as "0 hours", are at 23° C. (unless otherwise specified) and 50% relative humidity at a time of no more than 2 hours (120 minutes) after solidification from the melt of the adhesive under test. It is measured.

For example, the adhesive properties of hot melt formulations according to the present invention have optimum adhesive properties at "zero hours" (i.e., up to about 2 hours from solidification of the melt), and these properties are due to crystallization of the polymer fraction, After standing at room temperature, for example, after 5 days of coagulation, further improvement; It relates in particular to the adhesive properties known in adhesive technology under the designations “peel strength” and “shear strength”.

Further, with regard to the properties directly related to the adhesive strength of the hot melt formulation according to the present invention, as mentioned above, the formulation is usually prepared for a significantly longer period of at least 10 minutes, preferably at least 30 minutes, more preferably at least 60 minutes. It has "open time".

The physical properties of the hot melt formulation according to the present invention also show substantial changes over time due to delayed crystallization over time. In particular, they are soft and very tacky immediately after application in the molten state, so that they can exhibit excellent adhesion to various types of substrates; On the other hand, after crystallization is complete, it becomes much harder and physically stronger, usually within about 5 days, further improving the adhesive strength. Significant changes in the physical properties may be obtained, for example, by measuring the amount of change in surface hardness measured by a parameter called "needle penetration force" according to the ASTM D 1321-04 method; Alternatively, it becomes clearly significant by measuring the amount of change in tensile stress at break (or load at break) and elongation at break between 0 hours and 5 days. These two state-of-the-art properties are measured according to the ASTM D 638-14 method, varying for the following details:

- Test speed=300mm/min

- Dimensions of "dog bone" specimen: total length=73mm; Max Width=15mm; thickness=6.5mm; Length of the narrowest part of the center=19mm; Minimum width at the narrowest part of the center = 6.35mm.

As is well known to those skilled in the art of adhesive science, the good adhesion and physical properties of the hot melt adhesive formulations of the present invention and further substantial improvements over time are related to rheological parameters, such as modulus of elasticity (G') and tan It is expressed as a value of delta.

In general, hot melt adhesive formulations according to the present invention exhibit rather high tan delta values immediately after solidification from the melt, so that they can continue to flow even in the solid state and unexpectedly create strong adhesive bonds with the substrate; On the other hand, after standing/crystallizing at room temperature, for example, after about 5 days, the value of tan delta drops to a significantly smaller level. Conversely, the modulus of elasticity (G'), another rheological parameter immediately after the formulation is solidified from the melt, is relatively low, and its properties are soft and tacky; On the other hand, after standing and crystallization, G' has a much larger value to further increase the adhesive strength and physical strength of the bonding structure, and the residual tackiness of the adhesive formulation is reduced to a very low value, in some cases being zero.

Further, the aforementioned improvement in the properties of the hot melt adhesive formulation according to the present invention is caused by crystallization delayed over time, and at 0 hours (i.e. no more than 2 hours after solidification of the hot melt adhesive under test from the melt). It can be detected by the change present between the thermal profile of the adhesive formulation (as measured for example by DSC-differential scanning calorimetry) and the thermal profile of the same adhesive formulation measured for example after standing at room temperature for 5 days. have. In particular, an increase in the melting enthalpy of crystalline Form I of polybutene-1 having a higher melting temperature and an increase in the maximum melting temperature can be confirmed.

In addition, the hot melt adhesive formulations of the present invention have a low Brookfield melt viscosity, for example, a melt viscosity measured at a temperature of 170° C. of about 5,000 mPa·s or less, preferably about 3,500 mPa·s or less. In addition, their ring-and-ball softening point (measured according to ASTM D 36-95 method at 0 hours) is 120°C or lower, preferably 100°C or lower, more preferably 90°C or lower.

The properties of the low viscosity and low ring and ball softening point significantly improve the processability of the hot melt adhesive formulation according to the present invention compared to the hot melt formulations disclosed in the prior art, and by contact with the hot melt adhesive applied at too high a temperature. It permits their use even in contact with temperature sensitive or very thin substrates that can be damaged or deformed.

Processability by spraying and fiberization

The hot melt adhesive formulation according to the present invention has excellent processability in all application processes used in the hot melt adhesive industry.

However, one of its most surprising positive properties is optimum processability even at the highest speeds, a critical process in which many standard commercial hot melt adhesive formulations fail, for example, especially those by spraying and fiberizing. The same "shear rate" is the highest applied process.

To this end, without being bound by any specific process parameter values, for example, the hot melt adhesive formulations according to the invention exhibit optimum processability at line speeds of 800 m/min and higher, even in relatively less critical processes such as slot-die extrusion, ; Especially in critical processes such as spraying and fiberizing, it can be applied optimally even at line speeds of 400 m/min or higher.

Adhesives of the present disclosure can be processed by all application methods conventionally used for processing hot melt adhesives, as well as their unique optimum processability, which is also seen in particularly important processes such as spraying and fiberization, even at very high line speeds. It is emphasized again that it allows the formation of adhesives with the most surprising positive properties.

The application technique by spraying and fiberization offers several special advantages to the user as well as being able to significantly increase the productivity, especially when processes at very high line speeds are used, such as in the case of the adhesives of the present invention. For example, since these processes apply the adhesive without physical contact between the application head and the substrate, it is possible to laminate the adhesive even on heat-sensitive substrates that may be deformed or broken by direct contact with the metal head at high temperatures; Alternatively, the adhesive may be laminated even on a substrate having an irregular surface or on a particularly thin substrate, for example on a substrate such as a plastic film or a nonwoven fabric having a particularly low basis weight. In addition, in these processes, the adhesive covers only part of the surface of the substrate, for example in the form of threads stacked in a spiral, or as an irregular and discontinuous layer of very small droplets or very short fibers. Keeping substantial parts clean from usage can be substantially saved; or applying the adhesive onto a porous and air permeable substrate without substantially changing the characteristics.

In the patent literature referring to hot melt adhesives having particularly good sprayability, as well as the art of hot melt adhesives, the good or poor behavior of a particular adhesive in spraying and/or fibrillation is generally evaluated by visual judgment, U.S. Pat. No. 5,401,792 As in arcs, the characteristics and regularity of the geometric shape of the adhesive applied by these processes, for example, evaluated by the minimum achievable width of the spiral, or consistency of the diameter of the thread applied in the spiral, and the width of the spiral, as in the arc. is evaluated based on the consistency of

Thus, such judgments of good or poor sprayability of a particular hot melt adhesive based on the visual appearance of the final result in a particular experiment are not only dependent on the adhesive itself, but also on its operating parameters. Since it is clear that the specific application being applied - also depends on the characteristics of the head - because the consistency and regularity of a given feature is judged by the individual visual impression of the observer - it is clear that there are fundamental drawbacks in both objectivity and reproducibility. do.

In order to define the excellent processability in the spraying and fiberization of the hot melt adhesive formulation according to the present invention in a more objective, more accurate and reproducible way, in this specification, the good sprayability of the hot melt adhesive is described. It is mentioned in the document "UNDERSTANDING THE SPRAYABILITY OF HOT-MELT ADHESIVES" presented by 0. Georjon, M. Faissat, F. Chambon at the 1998 Hot Melt Symposium of TAPPI Proceedings, This document is incorporated herein by reference.

From the conclusion of the scientific studies discussed in this document, the hot melt adhesive formulation according to the present invention has a value of modulus of elasticity (G') of 10 Pa at the usual application temperature of the melt in the spraying or fiberizing process, i.e. an average temperature of 165 °C. It is particularly preferred that the value of the rheological parameter, called the viscous modulus (G"), when read corresponding to At this time, the hot melt adhesive formulation according to the present invention preferably has a tan delta value of 20 or more at a frequency of 10 Pa at a temperature of 165° C.

This means that even in the molten state, the hot melt adhesive formulations according to the invention exhibit a particularly low “elasticity of the melt”.

In the spraying and fiberizing process of the hot melt adhesive according to the present invention, a temperature of 165° C. selected from the molten state as a typical reference application temperature is used for absorbent hygiene products, absorbent care mats for medical use and surgical sheets, as well as packages, for example. It is desirable to emphasize that this is an ideal process temperature, which is widely used as a component in many other types of articles including

As will be apparent to those skilled in the art in the manufacturing process of the aforementioned articles, generally a temperature slightly lower or slightly higher than 165° C., explicitly in the range of from about 150° C. to about 180° C. can work However, it needs to be emphasized that an optimum temperature of about 165° C. and avoiding temperatures that are too far away are generally indispensable. If the temperature is too low, the hot melt adhesive cannot be processed in high-speed processes such as spraying or fiberizing due to excessive viscosity and excessive elasticity (excessive modulus (G')). It is even more important to avoid too high temperatures above 165°C, explicitly above 180°C. Indeed, such excessive temperatures in spraying or fiberizing can irreparably damage the heat-sensitive component of the article being produced, for example by melting and holing the polyolefin plastic film due to excessive heat.

Components of Hot Melt Adhesive Formulations According to the Invention

The hot melt adhesive of the present invention comprises two successive and separate reaction steps, wherein the first polymer (Polymer A) of the compositionally bimodal polymer composition is a homopolymer or isopolymer of isotactic butene-1 with another olipine. Polymerization, in the step that is a tactic butene-1 copolymer, whereas the second polymer (polymer B) is an isotactic copolymer of butene-1 with another olefin which is distinctly qualitatively and/or quantitatively different in chemical composition from polymer A comprising as a major polymer component at least one isotactic metallocene butene-1 polymer composition having a low viscosity (and thus relatively low average molecular weight) and substantially bimodal composition obtained directly upon Si; It further comprises a viscosity modifier that is not solid at room temperature.

Metallocene Polymer Composition of Isotactic Butene-1 with Low Viscosity and Bimodal Composition

At least one of these polymer compositions comprised in the hot melt adhesive formulation according to the invention is a polymer component, preferably alone or predominantly in the hot melt adhesive of the invention. A novel metallocene polymer composition of isotactic butene-1, a low viscosity, bimodal composition obtained directly upon polymerization in two successive and separate reaction steps, has been disclosed in two patent applications in Basell Poliolefine Italia EP 16178432.7 and EP 16178433.5 in detail, the contents of which are incorporated herein by reference.

In any case, each of them has a melt flow rate value measured according to ISO 113 at 190° C. under a load of 2.16 kg at 400 to 2,000 g/10 min, preferably 400 to 1800 g/10 min,

A) higher alpha having a three number or more carbon atoms having at least one comonomer selected from olefins and ethylene, the copolymerized comonomer content (C _A) is not more than 5 mol% or less, preferably 4 mole% butene- 1 copolymer or butene-1 homopolymer;

B) having at least one comonomer selected from higher alpha-olefins having 3 or more carbon atoms and ethylene, and having a copolymerized comonomer content (C _B ) of 6 mol% to 25 mol%, preferably 8% to It can be briefly described as a butene-1 polymer composition having a bimodal composition comprising 20% butene-1 copolymer.

In the polymer composition, the total content of the copolymerized comonomer is 4 mol% to 18 mol%, preferably 5 mol% to 155 mol%, based on the total weight of A) and B).

In the first embodiment of the present invention, the polymer composition has a content of at least 65% by weight, preferably at least 70% by weight of the xylene-soluble fraction at 0° C., and the xylene-soluble fraction comprises A) and B ) is determined for the total weight of

In a second embodiment of the present invention, the polymer composition has a content of the xylene-soluble fraction at 0°C of 60% by weight or less, preferably 55% by weight or less, and the xylene-soluble fraction comprises A) and B ) is determined for the total weight of

The components A) and B) are obtained directly during polymerization, preferably consisting of two successive and separate reaction steps, so that the polymer compositions described herein are free, even for sufficiently high overall MFR (low viscosity) values. Without the need for the use of peroxides or other substances that generate radicals, the molecular weight can be lowered further by breaking the polymer chain, and can be obtained directly during polymerization.

In a first embodiment of the present invention, for the butene-1 polymer composition as provided herein, the specified amount of the fraction soluble in xylene at 0° C. is determined by extracting with xylene relative to the total weight of A) and B). It is expressed as the weight content of the fraction measured, and ranges from 65% to 95% by weight, preferably from 70% to 90% by weight.

In a second embodiment of the present invention, for the butene-1 polymer composition as provided herein the specified amount of the fraction soluble in xylene at 0° C. is determined by extracting with xylene relative to the total weight of A) and B). It is expressed as the weight content of the fraction measured, and ranges from 35% to 60% by weight, preferably from 40% to 55% by weight.

When A) is a copolymer, the specific lower limit of the comonomer content is 1 mol%.

Preferably, when both A) and B) are copolymers, the difference between the percentage values of the copolymerized comonomer content of B) and A) satisfies the following formula:

(CB)-(CA)>5; or

(CB)-(CA)>6.

The relative amounts of components A) and B) can be easily determined according to the desired value of the total copolymerized comonomer content, the single component's comonomer content and the content of the fraction soluble in xylene at 0°C.

In the above-described first embodiment of the present invention, a preferred amount is based on the total weight of A) and B), wherein A) is 10% to 40% by weight, preferably 15% to 35% by weight, and B) is 60% to 90% by weight, preferably 65% to 85% by weight. In the above-mentioned second embodiment of the present invention, a preferred amount is based on the total weight of A) and B), wherein A) is 35% to 65% by weight, preferably 40% to 60% by weight, and B) is 35% to 65% by weight, preferably 40% to 60% by weight.

Particular examples of higher alpha-olefins having 3 or more carbon atoms which may additionally or alternatively to ethylene in components A) and B) be present as comonomers are alpha-olefins of the formula CH2=CHR, wherein R is an alkyl radical containing 3 to 8 or 3 to 6 carbon atoms, for example propylene, hexene-1, octene-1 or the like, or methyl.

However, ethylene is a preferred comonomer, especially for component B).

The butene-1 polymer composition of the present invention has a measurable degree of crystallinity as evidenced by the presence in a differential scanning calorimetry (DSC) pattern of the melting temperature peak of the crystalline fraction of polybutene-1.

In particular, the metallocene butene-1 polymer composition of the present invention having the bimodal composition exhibits one or more melting peaks in the second DSC heat scan. These melt temperature peaks or peaks, which generally occur at temperatures below about 110°C, mainly between about 75°C and about 110°C, are due to the melting of crystalline Form II of polybutene-1 (TmII), and the area under the peak is the total It is taken as a measure of the enthalpy of melting (ΔH TmII). If more than one melting peak is present, the peak corresponding to the highest temperature is taken as TmII.

More specifically, the metallocene butene-1 polymer composition having a bimodal composition used in the present invention has a total enthalpy of melting (ΔΗ TmII) of 20 J/g or less, particularly measured at a scan rate corresponding to 10° C./min. 3J/g~20J/g.

In addition, the butene-1 polymer composition of the present invention exhibits at least one melting peak in a DSC heat scan carried out after the material has been left at room temperature for a sufficiently long time, preferably at least 24 hours, more preferably at least 5 days. , which generally occurs at a temperature of 110° C. or less, in particular at a temperature of 30° C. to 110° C.

These temperature peaks or peaks are attributable to the melting point (TmI) of crystalline Form I of the butene-1 polymer, and the area under the peak (or peaks) is taken as the total enthalpy of melting (ΔH TmI). If more than one peak is present, the peak corresponding to the highest temperature is taken as TmI.

More specifically, the total enthalpy of melting (ΔH TmI) of the butene-1 polymer composition used in the present invention is 50 J/g or less, particularly 10-50 J/g or 15~ measured at a scanning speed corresponding to 10° C./min. 50 J/g.

Without wishing to be bound by any theory, the crystals of the stable hexagonal crystalline form of polybutene-1 (form I), as mentioned, provide the highest level of final adhesion and physical properties of the hot melt formulation according to the invention - many good It is preferred that the TmI -measured according to above - be rather high, since - when formed - is optimized; It is especially preferable that it is 60 degreeC or more, and it is still more preferable that it is 80 degreeC or more.

Preferred above-mentioned values of the total MFR of the metallocene butene-1 polymer composition having the bimodal composition used in the present invention are suitable for components A) and B) so that, in theory, almost all values can have respective MFR values. It can be obtained by combining in a ratio. However, in practice, the metallocene butene-1 polymer composition having the bimodal composition used in the present invention is preferably 100 to 2,000 g/10 min, particularly 100 to 2,000 g/10 min, so that the respective MFR values of the two components A) and B) are sufficiently high. Usually 200~1,800g/10min.

According to the prior art method, in the field of hot melt adhesives, the melt viscosity of the final adhesive and its components is sometimes measured according to ASTM D 3236-73, so-called "Brookfield Viscosity".

Under this aspect, the metallocene butene-1 polymer composition having a bimodal composition used in the present invention has a Brookfield viscosity measured at 180° C., preferably about 5,000 to about 50,000 mPa·sec, more preferably about 5,000 to about 30,000 mPa·sec.

In addition, the low viscosity metallocene isotactic butene-1 polymer composition having the bimodal composition used in the present invention exhibits at least one of the additional properties mentioned below:

- overall polydispersity (i.e. as determined by gel permeation chromatography for a composition consisting of components A and B) PDI=Mw/Mn, where Mw is the weight average molar mass, Mn is the number average molecular weight, less than 4 , preferably less than 3, more preferably less than 2.5, in all cases the lower limit is less than 1.5;

- the polydispersity of each component A or B is preferably not more than 2.5;

- Mw is at least 30,000, preferably between 30,000 and 100,000;

- an intrinsic viscosity measured in tetrahydronaphthalene (THN) at 135° C. of 0.6 dl/g or less, preferably 0.2 dl/g to 0.6 dl/g, more preferably 0.3 dl/g to 0.6 dl/g;

- the isotactic pentad (mmmm) measured by 13C-NMR operating at 150.91 MHz is greater than 90%, preferably greater than 93%, more preferably greater than 95%;

- 4,1 inserts cannot be detected using 13C-NMR operating at 150.91 MHz;

- yellowness as determined according to ASTM D 1925 is 0 or less, preferably 0 to -10, more preferably -1 to -9, even more preferably -1 to -5;

- the Shore D hardness value is 50 or less, preferably 45 or less, in particular 15-50, preferably 15-45;

- a tensile stress at break of 2 MPa to 25 MPa, preferably from 2 MPa to 20 MPa, measured according to ISO 527;

- the tensile elongation at break measured according to ISO 527 is from 100% to 1,000%, preferably from 450% to 700%;

- the glass transition temperature (Tg) is -22 °C or lower, preferably -23 °C or lower, the lower limit is -35 °C;

- The density at room temperature is 0.875 g/cm 3 or more, preferably 0.875 g/cm 3 to 0.92 g/cm 3 , more preferably 0.88 g/cm 3 to 0.90 g/cm 3 .

The hot melt adhesive formulation of the present invention comprises from about 10% to about 85% by weight, preferably about 30% by weight of at least one metallocene isotactic butene-1 polymer composition having a low viscosity bimodal composition as described above. % to about 65% by weight, more preferably from about 40% to about 55% by weight.

As already mentioned, the main object of the present invention is to formulate a hot melt adhesive formulation in the most suitable manner, and as used herein the novel isotactic metals having a low viscosity and bimodal composition obtained directly upon polymerization. The Rosene Butene-1 polymer compositions allow the final adhesive formulations of the present invention to generally demonstrate the unique properties of these novel specialty polymer compositions, particularly with respect to particularly effective time-delayed crystallization that occurs in the solid state and at room temperature. By combining with the optimum adhesive, rheological, physical and processing properties required for the selected quality of hot melt adhesives, the innovative and unique properties of this novel polymer composition are fully retained.

The formulation strategy and other components of the hot melt adhesive formulation according to the present invention used to achieve the above object are better described in the following paragraphs.

Other components of the hot melt adhesive according to the present invention

viscosity modifier

The hot melt adhesive formulations of the present invention include at least one viscosity modifier that is not solid at room temperature, ie, typically 23°C.

In the discussion of some patents in the prior art, the use of viscosity modifiers that are solid at room temperature (solid plasticizers; solid compounds that melt into very low viscosity liquids, etc.) can affect the crystallization of polybutene-1 in a very strong way. and consequently affect the adhesive properties of hot melt formulations formulated in this way; It has already been seen that, in at least two of the cases discussed, the solid plasticizer is a "temporary" hot melt adhesive that rapidly transitions from an immediate good adhesion state to a completely non-adhesive state after a rather short period of time.

Accordingly, adhesive formulations according to the present invention comprise at least one viscosity modifier that is not solid at room temperature. As explained in more detail in the paragraph of "Rules", the expression "not solid" means that the inspected object has its own volume but does not have its own shape; It can also be temporarily shaped into a specific shape but permanently deformed only by the action of its own weight and flow naturally (in a relatively short period of time, usually not longer than one day) to the shape of the container containing it or the solid surface on which it rests. refers to the state of matter that takes Thus, in the common language, as well as any substance that can be described as "liquid" in these definitions, "soft", "grass-like", "jelly-like", "fluid", "sticky", "semi-solid" Includes all substances defined as etc.

As is better explained in the paragraph of "Rules", viscosity modifiers that are not solid at room temperature that may be used in the present invention are defined as "rheologically liquid" at room temperature according to the rules given as adjectives in rheology. It may further include all materials, i.e. materials equivalent to the specification, wherein the viscous modulus (G") at the above mentioned temperatures exceeds their modulus of elasticity (G'); or the tan delta is greater than 1. The viscosity modifier further lowers the viscosity of the adhesive formulation in the molten state and increases the tack.

Viscosity modifiers or classes of viscosity modifiers that are not solid at room temperature that can be used in the adhesive formulations of the present invention include paraffinic mineral oil; naphthenic mineral oil; paraffinic and naphthenic hydrocarbons that are not solid at room temperature and mixtures thereof; oligomers that are not solid at room temperature of polyolefins and copolymers thereof, such as oligomers that are not solid at room temperature synthesized from ethylene, propylene, butene, iso-butylene and copolymers thereof; plasticizers that are not solid at room temperature, which are formed from esters such as phthalates, benzoates, and sebacates; vegetable oil; natural and synthetic fats; and mixtures thereof.

The mineral oil and grease, paraffinic and naphthenic and mixtures thereof are preferably non-solid oligomers of polyolefin as well as mainly non-solid oligomers of polypropylene and copolymers with ethylene. Among these state-of-the-art, preference is given especially to non-solid metallocene oligomers of polypropylene and copolymers with ethylene, in particular copolymers in which propylene is the predominant comonomer in mole fraction. In one embodiment of the present invention, a metallocene oligomer of propylene and a copolymer with ethylene, wherein the copolymer is propylene as the main comonomer, is not solid at room temperature, has a softening temperature of -30°C, and is 170°C. The viscosity at is 300 mPa.s or less.

Hot melt adhesive formulations according to the present invention comprise from about 5% to about 40%, preferably from about 8% to about 30% by weight of a viscosity modifier that is not solid at room temperature or a blend of a viscosity modifier that is not solid at room temperature, More preferably, it contains about 10% by weight to about 20% by weight.

adhesive

In one embodiment of the present invention, the adhesive formulation of the present invention further comprises at least one pressure-sensitive adhesive resin having a ring and ball softening point of 5°C to 160°C. Of the possible classes of tackifiers well known in the art of hot melt adhesives, preferred tackifiers for the formulations of the present invention generally belong to the class most compatible with polyolefins and polybutene-1. In general, the pressure-sensitive adhesives included in the formulations of the present invention include aliphatic hydrocarbon pressure-sensitive adhesives, and derivatives of which part or all are hydrogenated; aromatic hydrocarbon pressure-sensitive adhesives, and derivatives of which part or all are hydrogenated; aliphatic/aromatic pressure-sensitive adhesives, and derivatives of which some or all are hydrogenated; terpene pressure-sensitive adhesives, and derivatives of which part or all are hydrogenated; Rosin, its esters and some or all of them may be selected from hydrogenated derivatives. Fully hydrogenated hydrocarbon adhesives (aliphatic and aromatic and aliphatic/aromatic) have optimum compatibility with the isotactic metallocene polymer composition having a low viscosity bimodal composition used in the hot melt adhesive according to the present invention. Especially preferred. It has also been found that it is preferable that the ring-and-ball softening point of the pressure-sensitive adhesive resin used in the formulation of the present invention is about 80°C or higher, preferably about 90°C or higher, and more preferably about 100°C or higher.

In embodiments of the present invention wherein the hot melt adhesive formulation comprises at least one tackifier resin, they contain from about 15% to about 70%, preferably from about 25%, by weight of the at least one tackifier resin or mixture of tackifier resins. to about 60% by weight, more preferably from about 30% to about 55% by weight.

additional components

As can be seen, most of the prior art is made by mixing isotactic polybutene-1 synthesized with a spherical Ziegler-Natta catalyst at high viscosity with a large amount of other polymer compounds present in a significantly greater percentage than polybutene-1. teach formulating.

One of the main purposes of adding these large amounts of different polymers is to determine the properties of the adhesion, cohesiveness and processability (given the very initially very high viscosity of polybutene-1) of the hot melt adhesive formulation formulated in this way. is to improve A very frequently used class of polymers used in this range are APAOs (amorphous-poly-alpha-olefins).

In contrast, the present invention uses the novel metallocene isotactic polybutene-1 composition described above having a substantially bimodal composition with surprisingly low viscosity and a narrow bimodal distribution for both composition and molecular weight, thereby providing the present invention. In order to improve the adhesion, cohesiveness and processability of the formulations according to the invention, it is no longer necessary to add large amounts of other polymers, in particular APAO, which may adversely affect the subsequent crystallization delayed with time.

Accordingly, the hot melt adhesive formulation according to the present invention preferably comprises at least one novel metallocene isotactic poly having a bimodal composition with a substantially low viscosity as described above, independently of what is specified below for a particular polymer. It does not contain any polymer other than the butene-1 composition. In particular, the formulation preferably does not comprise a substantially amorphous polymer, such as an amorphous poly-alpha-olefin (APAO). And, regardless of the reason for adding a small amount of APAO or other polymer different from the metallocene isotactic butene-1 polymer composition described above, the total level of these different polymers in any case judged suitable is the total hotmelt composition. of 15% by weight or less, preferably 10% by weight or less.

Also, surprisingly, the adhesive formulations of the present invention contain a significant amount of high crystallinity wax or other addition added as a nucleating agent to facilitate and promote the crystallization of this polybutene-1, contrary to what is taught by some of the prior art. It has been found that the addition of components is not required. In contrast, large amounts of wax or other similar crystalline compounds may interfere with the slow and regular crystallization of the unique metallocene isotactic butene-1 polymer composition used in the hot melt formulations of the present invention, which results in faster and more disordered crystallization. , resulting in too many, on average smaller and less rigid crystals, potentially deteriorating adhesion and physical properties.

However, very small amounts of waxes, especially polyolefin waxes and polypropylene waxes, specifically waxes modified with maleic anhydride, are added to the hot melt formulation of the present invention in an amount of about 5% by weight or less, and thus are not included in the formulation of the present invention. Without substantially interfering with the main mechanism of the time-delayed crystallization of the included metallocene polymer composition of isotactic polybutene-1, some properties, such as "open time", for example, can be improved in a most suitable manner. have.

Likewise, it has been surprisingly found that small amounts of semi-crystalline polymers, preferably semi-crystalline copolymers of propylene, in particular copolymers of propylene and ethylene, can improve some properties of the hot melt adhesive formulations of the present invention; For example, if the semi-crystalline polymer is added in small amounts, about 15% by weight or less, preferably about 10% by weight or less of the hot melt adhesive, it does not significantly increase the viscosity in the molten state and is the basis of crystallization of the formulation itself. The "open time" can be adjusted better than wax without substantially interfering with properties and good processability.

In certain embodiments of the present invention, the semi-crystalline copolymer of propylene and ethylene has a heterophasic morphology, such as, for example, a polymer composition and heterophasic copolymer sold under the trademark Hifax from Lyondell-Basell. Copolymers of propylene and ethylene and other heterophasic semi-crystalline polymer compositions that can be used in the adhesive formulations of the present invention in amounts of up to about 15% by weight, preferably up to about 10% by weight, are, for example, trademarks of ExxonMobil. They are marketed as Vistamaxx.

In addition, the hot melt adhesive of the present invention comprises, as a main polymer component, at least one metallocene isotactic polymer composition of low-viscosity butene-1, and a bimodal composition obtained directly during polymerization, and according to the above, any It may further include a homopolymer or copolymer of isotactic butene-1 derived from metallocene having a low viscosity monomodal composition as a secondary polymer component of about 15% by weight or less. The low viscosity of the homopolymer or copolymer of isotactic butene-1 derived from metallocene having a monomodal composition is 200-2,000, preferably 500-1,600, expressed as a melt flow rate measured according to ISO 1133.

Hot melt adhesive formulations according to the present invention may further comprise from about 0.01% to about 10% by weight of at least one stabilizer, such as antioxidants, anti-UV light stabilizers, and mixtures thereof. They may further comprise up to about 15% by weight of other additional optional components such as mineral fillers, pigments, dyes, fragrances, surfactants, antistatic agents.

Main Adhesive Parameters

The adhesive properties of formulations according to the invention and their change over time, as well as the adhesive properties of adhesive formulations of other comparisons, can be evaluated by three types of parameters:

i. A parameter called "open time", i.e., the time interval after which the melt is applied on the first substrate, during which the hot melt adhesive can form a sufficiently strong adhesive bond with a second substrate in contact with the first substrate under moderate pressure for its intended use. . In particular, the open time of the hot melt formulation under test is measured according to test method ASTM D 4497-94, and the following conditions for the hot melt adhesive formulation are considered:

- Coating temperature of adhesive film: 170℃

- Thickness of adhesive film = 1mm

ii. The adhesive property known as the "peel strength", i.e. the average force per unit length, required to separate two substrates bonded by the adhesive composition under test, the force being determined by the separation at a constant rate and held at a constant angle of separation . Measured according to the test method ASTM D 1876-01, the separation speed between the two substrates is 150 mm/min applied, so the moving speed of the testing machine is 300 mm/min. The two substrates used are a 22 g/m microporous polyethylene film onto which a melt adhesive is sprayed in a molten state or applied directly by slot-die extrusion, on which a 12 g/m spunbond polypropylene nonwoven fabric is immediately adhered. The measurement of the peel strength was made by recording the strength required to peel the two adhered substrates to a width of 50 mm.

iii. The adhesive property known in the art as "shear strength", i.e. the longest time that two substrates bonded by the adhesive formulation under test can support a fixed, suspended weight without breaking the bond. The adhesive properties are measured according to ASTM D 3654 method, and are modified as follows:

- 1st base material: Mylar film, 50g/m2

- 2nd substrate: kraft paper, 40g/㎡

- the adhesive is coated with a basis weight of 50 g/m 2 on the mylar film from the melt at 170° C. by a manual lab coater and immediately bonded to the paper:

- Joint area for testing: 1 square inch (i.e. 1 inch square area per side)

- Weight: 1kg

- Temperature of test chamber: 40℃

For the shear strength test, the samples at 0 hours are tested immediately after manual bonding. In contrast, after bonding the samples on day 5, they are left for 5 days in a room at 23° C. and 50% relative humidity, at which time no weight is applied. After 5 days, test the shear strength of the left-in samples according to the previously described procedure.

Embodiments according to the invention

The invention is better illustrated by the following examples, which are for illustrative purposes only and should not be construed as limiting the scope of the invention or how it may be practiced. Unless otherwise specified, parts and percentages are expressed by weight.

Isotactic metallocene butene-1 polymer composition having a low viscosity bimodal composition used in Examples according to the present invention

To formulate the examples according to the invention, an isotactic metallocene butene-1 polymer composition is used in combination with a bimodal composition obtained directly upon polymerization in two successive and separate reaction steps with low viscosity as described above. became The bimodal isotactic polybutene-1 composition was supplied by Basell Poliolefine Italia, hereinafter referred to as polymer PB-X1. It is characterized by the characteristics summarized in Table 1.

Example 1

The following hot melt adhesive formulations according to the present invention are prepared by mixing the components in a molten state at 170°C:

The hot melt adhesive formulation of Example 1 comprises the metallocene isotactic polymer composition PB-X1 described above with low viscosity as the sole polymer component, the composition comprising a copolymer between polybutene-1 and ethylene and polybutene -1 (as described in more detail in Table 1), all metallocene isotactic, low viscosity/low molecular weight, and the polymer composition according to the present invention consists of two continuous and It is obtained directly during polymerization in individual reaction steps.

The adhesive formulations described above are easily processable due to their particularly low viscosity of 2,050 mPa·s at a temperature of 170°C. It also meets the rheological criteria used for processes at high and high shear rates, such as spraying or fibrillating: the value of the viscous modulus (G") corresponding to the modulus of elasticity (G'), which is in fact 10 Pa at 165° C. is 211 Pa, and thus the value of tan delta is 21.1, which meets the rheological criterion for good sprayability of hot melt adhesives.

This formulation has a low ring and ball softening point of 78° C. and an exceptionally long “open time” of 120 minutes for formulations based on polybutene-1; Its use is therefore particularly easy and effective in a variety of possible bonding processes.

This combination of superior properties actually leads to good processability at various application processes and at various conditions of line speed and/or temperature. For example, the adhesive formulation of Example 1 was optimally processed by slot die extrusion at a line speed of 250 m/min to 600 m/min and a temperature of 155° C. to 165° C.; It was also machined by spraying at line speeds of 250 m/min to 600 m/min and temperatures between 155°C and 170°C. In all cases, the processability was good, and the adhesive layer coated by extrusion or spraying was always perfectly uniform and regular.

In addition, the formulation of Example 1 is a low viscosity, isotactic, metallocene polymer composition PB-X1 of polybutene-1 itself, due to its delayed, fairly good, ordered, and robust crystallization over time. It exhibits excellent ability to change the rheological, physical and adhesive properties of

The surprising effect of crystallization delayed with time in the metallocene polymer composition of polybutene-1 is, for example, a tensile strength at break of 0.02 MPa at 0 hours at 23° C. After that, the value is as high as 1.3 MPa and increases 64 times, thus increasing by 6,400% as a percentage; At this time, the elongation at break exceeds 4,040% at 0 hours (which is the highest full-range value measured by the instrument used), and the amount of change between the two times after 5 days at 23°C (calculated based on the 5-day value) ) is 11.1 times or more, or is well expressed as 1,110% or more.

In addition, in the hot melt adhesive formulation of the present invention, the characteristic change that occurs due to crystallization delayed over time is well represented as a significant change in rheological properties. For example, the value of the elastic modulus (G') at 0 hours at 23° C. and a frequency of 1 Hz is very low, 0.0687 MPa, while the rheological parameter, tan delta, is greater than 1, more precisely 1.18.

As will be readily appreciated by those skilled in the art of rheology and adhesive science, the above values of these rheological parameters indicate that the adhesive formulation of Example 1 at room temperature in the solid state immediately after solidification from the melt was initially superior to the substrate. It means an adhesive that is very soft and tacky to provide an adhesive bond. In addition, the high value of tan delta at 23° C. expands the bonding area by continuing to “flow” and “wet” on the substrate even when the adhesive is already in a solid state after forming an adhesive bond, thus enlarging the overall adhesive strength. means to increase proportionally.

However, due to the surprisingly effective and robust time-delayed crystallization, the special ability of this formulation to "cure" over time is not demonstrated by simple standing at room temperature, for example after 5 days, with the same rheological parameters. It is well emphasized by the change. In fact, the value of the modulus of elasticity (G') at room temperature and 1 Hz after standing at 23° C. for 5 days is very high as 6.52 MPa; That is, due to the surprisingly ordered, effective, and strong crystallization of the unique isotactic metallocene polymer composition of polybutene-1 that forms the polymeric base of these novel hot melt adhesives, G' is 93.9 times, or as a percentage. It increased by 9,390%.

The exceptional increase in the modulus of elasticity (G') shows how well the formulation of Example 1 was transformed into a naturally very hard adhesive, i.e., how much the adhesive strength and physical strength of the adhesive force were enhanced since the adhesive bond was first formed. indicates.

Also, due to the same crystallization phenomenon at this time, the parameter tan delta is significantly reduced; In fact, after standing at room temperature for 5 days, the value of tan delta is 0.267, which means that it is usually a much harder solid, no longer "flowing", and the final property "flowing" as better explained in the previous paragraph is more Not only is it not necessary anymore, it can have very detrimental effects.

Thus, due to the particularly regular and robust crystallization of the unique novel polymer composition of polybutene-1 used herein, the parameter tan delta of the adhesive formulation of Example 1 was maintained at room temperature for only 5 days, thereby reducing the difference between two hours. The amount of change (calculated based on the values on day 5) is more than 3.4 times, or about 342%.

Abnormal hardening by crystallization of the adhesive of the present invention is measured whether the adhesive is soft and tacky and can be bonded very well from the beginning, or, conversely, whether the adhesive is hard and has peel resistance to withstand the breakage of the adhesive bond (inversely proportional to the value) The significant change in needle penetration force, a parameter to Indeed, the formulation of Example 1 is a very soft and tacky material with a very high needle penetration of 125 dmm at 23°C; After 5 days it still transforms into a harder and more resistant adhesive with low needle penetration at 23° C. of 16 dmm. Thus, the adhesive changes its penetrating power more than 6.8 times or 681% (calculated as a percentage based on the value on day 5) between two hours.

Finally, although some is already clear from the above, the formulations of this example according to the present invention show a dramatic change in their surface tackiness at room temperature with time-delayed progress of crystallization; In fact, this material transforms from an adhesive with high tack initially to a final adhesive without residual tack, especially during standing at 23° C., a property that is very important and noteworthy for many applications.

Example 2

The hot melt adhesive formulation according to the present invention was prepared by melt mixing at 170 °C:

The formulation further uses a small amount of amorphous-poly-alpha-olefin (APAO) in addition to the metallocene polymer composition PB-X1 of low viscosity polybutene-1.

This addition is essentially done to further increase the initial tackiness of the formulation. However, contrary to most prior art teachings, the polymer is amorphous, a polymer chemically different from the metallocene polymer composition of butene-1, and is used herein in much lower amounts than the main polybutene-1, It does not interfere with its subsequent crystallization, which is delayed over time, since this crystallization occurs in a particularly effective, regular and robust manner, resulting in improved adhesion and physical properties.

Also, despite the presence of an amorphous polymer different from the polybutene composition PB-X1, the formulation of Example 2 exhibits a low viscosity of 2,390 mPa·s at 170°C. In addition, it has a value of its viscous modulus (G") of 254 Pa, which corresponds to a value of its elastic modulus (G') of 10 Pa at 165° C., and thus its tan delta is 25.4, which is the rheology for the good sprayability of the hot melt adhesive. It fully meets the applicable standards and has excellent processability even in high-speed and high-shear rate processes such as spraying or fiberizing processes, as indicated by the fact that it is a very high value indicating good flowability and sprayability of this formulation.

The ring and ball softening point is 84.2° C., and the open time is about 45 minutes, which is quite long.

As with Example 1 before, the formulation of Example 2 showed optimum processability at different line speeds and temperatures over a wide range of different operating processes.

In addition, this formulation was applied by slot die extrusion at a line speed of 250 m/min to 600 m/min and a temperature of 155° C. to 165° C.; It was also treated by spraying at a line speed of 250 m/min to 600 m/min and a temperature of 155° C. to 170° C. In all cases, the processability was good and the adhesive layer coated by extrusion or spraying was always perfectly uniform and regular.

In addition, this formulation of Example 2, due to the time-delayed crystallization of the novel polymer composition of polybutene-1, which is generated with excellent effect in spite of the presence of the amorphous polymer APAO by standing at room temperature, its adhesiveness, Significant changes in rheological and physical properties further improve its performance.

In practice, for example, the tensile stress at break of this formulation at 23° C. has a low value of 0.04 MPa at 0 hours, and has a value of 1.36 MPa after standing at room temperature for 5 days, i.e. more than 34 times, and also 3,300% increases; On the other hand, the elongation at break at 0 hours is greater than 4,040% (which is the highest full-range value measured with the instrument used), and after 5 days it drops to 287%, i.e., a decrease of more than 14 times, or the elongation at break is greater than 1,300% The rate of change (calculated based on the final value on day 5) is shown.

In addition, the rheological properties in the solid state and at room temperature show unexpected changes over time. In fact, for example, the value of the modulus of elasticity (G') at 0 hours at 23°C and a frequency of 1 Hz is as low as 0.055 MPa, and the value after standing at room temperature for 5 days is 4.81 MPa, which is more than 86 times or about 8,645%. increased by an unexpected amount; At this time, the parameter tan delta measured under the same conditions decreased from a high value of 0.984 at 0 hours to a low value of almost 0.2 after standing at 23°C for 5 days, and the amount of change with time (based on the value on the 5th day) calculated) is about 4 times, or 392%. That is, the formulation of Example 2 is a very soft, tacky material capable of "flowing" in spite of good cohesiveness initially immediately after curing from the molten state, so that it wets the substrate very well and forms a good initial adhesive bond. It is an adhesive. However, the characteristic optimal behavior in the time-delayed subsequent crystallization of the novel polymer composition of polybutene-1 used herein further strengthens the adhesive formulation by simply leaving it over time at room temperature, It is transformed into a harder component to further improve adhesion and physical properties.

Likewise, the needle penetration force at 23° C. was changed from 28 dmm at 0 hours to 12 dmm after 5 days, that is, the rate of change with time (calculated based on the value on day 5) was 133%, which was further lowered to less than half.

As in the previous examples, the hot melt adhesive formulation of this Example 2 dramatically changes the properties of surface tackiness while standing at room temperature due to the phenomena described above. This formulation transforms from an adhesive that is very tacky at zero hours and can instantly produce a good initial adhesive bond to a final adhesive that has no residual tack after standing.

Example 3

The following hot melt adhesive formulations according to the present invention were prepared by melt mixing at 170°C:

In addition, in this formulation a polymer different from the polymer composition PB-X1 of polybutene-1 was added in a very small amount of almost 1%. However, in the present invention this different polymer is a heterophasic semi-crystalline polymer, which has a polypropylene base and contains a fraction of a propylene-ethylene copolymer.

The presence of a small amount of the semi-crystalline polymer, even in spraying and fibrillation, does not interfere with the excellent processability of this formulation and does not change its very low viscosity, and the properties related to the delayed crystallization of the polymer composition PB-X1 with time. can be further improved.

In fact, the viscosity at 170° C. is as low as 2,575 mPa·s; The value of the viscous modulus (G") of the present formulation corresponding to the value of the elastic modulus (G') of 10 Pa at 165° C. is as large as 332 Pa, and therefore its tan delta is as large as 33.2, thereby providing excellent sprayability of the hot melt adhesive It shows very good fulfillment of the rheological criteria for

In addition, the low Lang and Ball softening point of 83.7° C. and a fairly long open time of about 80 minutes indicate ease and effectiveness, so the adhesive formulation of Example 3 is suitable for processing at high rates and high shear rates such as spraying or fiberizing. It can be used in a variety of application processes beyond

Also, in fact, like the two previous examples, the adhesive formulation of Example 3 exhibited optimum processability in a variety of different operating processes at different line speeds and temperatures.

Also, regarding the formulations of the previous two examples, this formulation was applied by slot die extrusion at a line speed of 250 m/min to 600 m/min and a temperature of 155° C. to 165° C.; The treatment was done by spraying at a line speed of 250 m/min to 600 m/min and a temperature of 155° C. to 170° C. In all cases, the processability was good and the adhesive layer coated by extrusion or spraying was always perfectly uniform and regular.

In addition, the change in properties due to the time-delayed crystallization of the low-viscosity metallocene polymer composition of polybutene-1 included in the formulation of Example 3 is also optimal.

For example, the tensile stress at break at 0 hours at 23° C. is as low as 0.04 MPa, and after standing at room temperature for 5 days, it increases to a large value of 1.72 MPa, indicating a significant increase of 42 times or 4,200%, which in the present specification This is due to the unusually ordered and rigid crystallization of the novel metallocene polymer composition of isotactic polybutene-1 used.

At this time, the elongation at break at 0 hours is more than 4,040%, and changes to 327% after 5 days at 23°C; In other words, the elongation at break is 1,135% ( calculated based on the values on day 5).

Significant changes in the physical properties of this hot melt adhesive formulated in accordance with the teachings of the present invention are well represented by similar changes in rheological properties. For example, the value of the modulus of elasticity (G') at 0 hours at 23° C. and a frequency of 1 Hz is as low as 0.0676 MPa, so the adhesive of the present invention is a very soft and tacky component at first, and only for 5 days at room temperature. It was proved to have a very high value of 6.07 MPa after standing; That is, the slow crystallization at room temperature of the hot-melt adhesive of the present invention comprising one of the novel metallocene polymer compositions of isotactic polybutene-1 having a bimodal composition according to the present invention occurs after standing at 23° C. for 5 days. may increase, and the value of the modulus of elasticity (G') is greater than 88 times, or greater than 8,879%.

At this time, the parameter tan delta measured under the same conditions decreased from a high value of 0.933 at 0 hours to a much lower value of 0.296 after standing at 23° C. for 5 days; That is, the tan delta exhibits a change with time (calculated based on the value on day 5) of more than double, more precisely, 215%.

During the same period, needle penetration had a rate of change (calculated based on the value at day 5) of 236% from 37 dmm at 0 hours to 11 dmm after 5 days.

With respect to the adhesive formulations of Examples 1 and 2, the hot melt adhesive formulation of Example 3 also exhibited a very strong change in surface tackiness due to the above-described phenomenon during standing at room temperature.

In fact, the adhesive formulations of the present invention are very tacky at 0 hours, so they can form an immediate adhesive bond with many substrates; During standing, the adhesive eventually transforms into a completely non-tacky adhesive, a property that is very important and valuable in many applications.

comparative example

In the comparative example below, as taught by the present invention, a low viscosity isotactic metallocene polymer composition of butene-1 having a substantially bimodal composition obtained directly upon polymerization in two successive and separate reaction steps. Instead, it was formulated using several spherical polybutene-1s of high viscosity synthesized with a commercially available Ziegler-Natta catalyst; The polybutene-1 using the Ziegler-Natta catalyst in the comparative example below was formulated into a hot melt adhesive according to the standards using the components taught by the prior art.

Comparative Example 1

The following hot melt adhesive of Comparative Example 1 was prepared using spherical commercially available polybutene-1 synthesized with a Ziegler-Natta catalyst, as taught by the prior art, and using ingredients and formulation related standards. The adhesive exhibits very high viscosity and was prepared by melt mixing at 185°C.

Comparative Example 1 comprises a physical mixture of two different polybutene-1 spheres obtained by only melting and mixing. The first commercially available polybutene-1 is a copolymer of butene-1 and ethylene, and the second polybutene-1 is a homopolymer of polybutene-1, all synthesized using a Ziegler-Nathan catalyst, and all have very high viscosity/ It has a molecular weight, is synthesized by two completely independent reactions, and is commercialized as two separate polymers, in this case physically by melting and mixing only in the preparation of the hot melt adhesive formulation of the present invention of Comparative Example 1. mixed

In addition, for the purpose of increasing the tack and cohesiveness of the formulations of the present invention, as taught by the prior art, this adhesive is formulated to contain an amorphous-poly-alpha-olefin (APAO) with an overall level of two polybutene-1s. It contains a significantly higher amount (30% by weight) in excess of the level.

In order to ameliorate the poor and qualitatively inadequate crystallization delayed with time at room temperature of the physical mixture of the present invention of two different polybutene-1s all synthesized with Ziegler-Natta catalyst, the prior art has developed a very high level of It is taught to further add a polypropylene wax having a degree of crystallinity in a significantly higher amount (19.5% by weight), the purpose of which is to act as a nucleating agent and a center of crystallization, so that To promote and ameliorate insufficient and qualitatively inadequate crystallization delayed over time.

However, the introduction of such a large amount of crystalline wax leads to several additional disadvantages: for example, the open time of the adhesive of the present invention drops to an unacceptably low level, in this case as low as only 40 seconds, so much This makes the application of this adhesive difficult in a wide variety of processes that require longer open times. As will be apparent to one skilled in the art of hot melt adhesive science, the addition of such large amounts of crystalline wax makes the adhesive itself too hard and much less tacky, resulting in other drawbacks described in more detail below.

The adhesive formulation of Comparative Example 1 based on polybutene-1 of the Ziegler-Natta type of high viscosity and high molecular weight actually exhibits a much more serious disadvantage for use as a hot melt adhesive.

For example, the ring and ball softening point is unacceptably high, as high as 156.8°C; This fact, which is associated with a very high viscosity of 9,660 mPa.s at 170° C., as will be clear to the person skilled in the art, makes it essential to use the adhesive formulation of Comparative Example 1, especially at too high a temperature. In processes and articles such as, for example, absorbent hygiene products, which contain some heat sensitive components such as polyethylene films and polyolefin nonwovens which may be immediately damaged or destroyed by the applied adhesive, such hot melt adhesives are treated in a correct way and It speaks well of how difficult it is to apply.

The very difficult processability of the above adhesive is even more difficult in the most important processes at high rates and high shear rates, such as spraying and fiberizing. In practice, the very high viscosity adhesives of the present invention cannot be processed by these two processes.

For example, it does not meet the rheological criteria for good sprayability of hot melt adhesives: in fact, the value of the modulus of viscosity (G") corresponding to the value of modulus of elasticity (G') of 10 Pa at 165°C is 133 Pa. It is low and therefore has a tan delta of 13.3, which is very low for use in hot melt adhesives melted at high temperatures, clearly indicating very poor flowability and inability to spray.

Even in application processes less critical than spraying, the processability of these adhesives is in any case very poor. For example, coating on a polyethylene film by slot die extrusion at a relatively low speed of 250 m/min while varying the temperature from 160° C. to 170° C. to find the best conditions for the best extrusion; Even if it was possible to obtain a sample of the adhesive-coated film (different from that observed in the formulations of the other three comparative examples - see below), the quality of the adhesive layer coated on the film was in all cases regular and uniform. dissatisfied with sex

The fact that the adhesive formulation of Comparative Example 1 is based on high viscosity spherical polybutene-1 synthesized with a Ziegler-Natta catalyst, as well as the fact that it contains a very large amount of an amorphous polymer such as Rextac 2715 as APAO, is affects the very low effectiveness of crystallization, which is delayed over time in

First of all, this fact is evident from the values of physical properties and changes with time during standing at 23°C.

For example, the tensile stress at break at 0 hours is 3.18 MPa; That is, already at time 0, the formulation of Comparative Example 1 is a very hard solid, so it may be difficult to act as a good adhesive.

After standing at room temperature for 5 days, the tensile stress at break at 23° C. increases slightly, due to delayed crystallization of the two polybutene-1s included herein. However, the crystallization is too inefficient, the quality is poor, and it is hampered by a large amount of amorphous polymer APAO, so that the tensile stress at break after 5 days increases to only 4.40 MPa, with an increase rate of 38.4%.

Similarly, the value of the elongation at break at 23 ° C. is very low, from 0 hour to 220%, and shows a very small amount of change that changes to 193% after being left at room temperature for 5 days, and the amount of change with time (calculated based on the value on the 5th day) ) is as small as 14%.

The same phenomenon is better represented by the trend of the rheological parameters over time at room temperature.

For example, the modulus of elasticity (G') at 23° C. and 1 Hz frequency of the hot melt formulation of Comparative Example 1 has a very high value of 1.28 MPa at 0 hours, so this material is very hard from the beginning and has almost no adhesiveness. It is confirmed that there is no adhesive, and it is not possible to form a good and hard initial adhesive bond due to the very short open time of only 40 seconds.

This is further confirmed by the value of the parameter tan delta, which is very low with a value of tan delta at 0 hours at 23° C. and still at a frequency of 1 Hz, almost 0.276, which prevents this adhesive from flowing poorly and wetting the substrate. Because it is well shown, a good initial adhesive bonding cannot be formed.

In addition, the change over time of these rheological parameters is relatively small due to inefficient delayed crystallization. For example, at 23° C. and 1 Hz, the elastic modulus (G′) after 5 days at room temperature increases to 26.4 MPa; On the other hand, the parameter tan delta is further reduced to a value of 0.219. Therefore, G' represents an increase rate of 1,962%, and tan delta represents a low amount of change with time (calculated based on the value on day 5) of 26%.

When the above-described change amount is converted into a percentage, in particular, the change amount of the elastic modulus (G') can be considered significant.

However, these changes are significantly lower than the amounts of change equivalent to those exhibited by adhesive formulations according to the present invention, as well as due to excessive viscosity, inadequate processability, hardness after the initial moment, poor wettability and flowability on the substrate, compared Since the poor quality of the initial adhesive bond that the hot melt formulation of Example 1 can form with the substrate cannot achieve an intimate, good contact between the adhesive and the substrate, the strength can be improved by increasing the modulus of elasticity (G') or reducing the tan delta. It cannot be increased, nor can it be effected in a substantially positive way, and consequently it is "unusable" due to the above-mentioned drawbacks in the initial behavior of the adhesive of the present invention.

Due to unsatisfactory crystallization in both qualitative and quantitative terms of polybutene-1 synthesized with the Ziegler-Natta catalyst included in the formulation, the needle penetration power of the formulation of Comparative Example 1 is also changed relatively little. In fact, needle penetration as low as 6 dmm initially at 23°C (confirming that this formulation is a very hard and very little tacky ingredient) changes to 3 dmm after standing at room temperature for 5 days. Although this value is formally 100% low as a percentage (calculated based on the value after 5 days), it is an invalid change of 3dmm in absolute value, and is practically completely negligible.

Comparative Example 2

The hot melt adhesive of the comparative example below was prepared according to the teachings of the prior art and polybutene-1 synthesized with a commercially available Ziegler-Natta catalyst.

Due to their exceptionally high viscosity, the adhesives shown below were prepared by melt-mixing at 185°C.

Again in this case, according to the teachings of the prior art, two different commercially available polybutene-1s are used, all synthesized with a Ziegler-Natta catalyst, and physically mixed together in the molten state at the moment the hot melt adhesive is prepared. These polybutene-1 were mixed with butene-1 and a copolymer of about 6% ethylene, and a homopolymer of polybutene-1 in a weight ratio of 60:40.

According to this teaching of the prior art, the only additional component other than the antioxidant is a hydrogenated hydrocarbon tackifier resin.

The hot melt adhesive of Comparative Example 2 exhibits much more drawbacks than the previous Comparative Example 1, particularly very high viscosity, very poor processability in both low and high speed processes, and poor rheological properties, and thus cannot act as a good hot melt adhesive.

In addition, due to the inefficient crystallization of the physical mixing of the two polybutene-1 synthesized with the Ziegler-Natta catalyst, the change in properties with time is not completely satisfactory.

For example, the ring and ball softening point is as high as 112.8°C; The viscosity in the molten state of the hot melt adhesive was surprisingly high at 170° C., 50,200 mPa·s.

Both of these parameters make the adhesive according to Comparative Example 2 to have very difficult processability and, above all, to be absolutely used in the production of articles such as absorbent hygiene articles such as polyolefin plastic films and polyolefin nonwoven fabrics comprising heat-sensitive components. It tells you what's not right.

Obviously, the adhesive of the present invention having these physical properties cannot be fully processed, especially in high-speed processes such as spraying and fiberizing, in practice, for example, a comparative example corresponding to a value of its elastic modulus (G') of 10 Pa at 165° C. The viscosity modulus (G") of the hot melt adhesive of 2 is very low, 105 Pa; that is, the tan delta in the molten state at 165 °C is only 10.5, which does not significantly meet the rheological criterion for good sprayability of the hot melt adhesive. does not

Due to their very high viscosity and poor rheological properties, they cannot be processed even by processes less affected than spraying, such as slot-die extrusion. Indeed, even at a relatively low speed of 250 meters/min, all attempts to extrude by coating an adhesive on a polyethylene film have failed, even when changing the temperature between 155°C and 170°C.

In addition, even when the very short open time of only 110 seconds, i.e., the time this adhesive can bond and bond the substrates, how much is it to use the adhesive formulation of Comparative Example 2 in various industrial processes that require a much longer open time? indicates that it is impossible.

At 0 hours, the tensile stress at break of the adhesive at 23° C. is relatively high as 0.34 MPa; The elongation at break is 2,640%. Therefore, although this adhesive is a relatively resilient component, it can be difficult to act as a good adhesive.

After standing at 23 DEG C for 5 days, the tensile stress at break at room temperature increased to 6.59 MPa, that is, the increase rate was 1,838%; Elongation at break is reduced to 247%, resulting in a rate of change (calculated based on day 5 values) of 969%.

These values of change may represent high values, but in fact, in addition to markedly worse than the values of change of equivalents exhibited by the formulation according to the invention, in fact, as already evident in the previous Comparative Example 1, the aging of the physical properties The change is not at all effective in improving by broadly strong contact a substantially weak adhesive bond from the outset, since the adhesive of the present invention has, in theory, a weak ability to wet the substrate and a weak ability to adhere strongly after 0 hours.

As will be clear to those skilled in the art of hot melt adhesive science, this fact is evident not only in the molten state (see above), but also at room temperature, when the rheological properties of the adhesives of the present invention are investigated with the lapse of these rheological properties by standing at 23° C. It becomes clearer by analyzing the change.

At time 0, the above-mentioned adhesive has a significant value of elastic modulus (G') of 4.915 MPa at 23° C. and a frequency of 1 Hz, whereas the tan delta is only 0.57. These values indicate that the formulation of Comparative Example 2 is an adhesive that is initially very hard and hardly tacky, and has poor good wetting and good adhesion to the substrate.

After standing at room temperature for 5 days, the value of the elastic modulus (G') at 23° C. and 1 Hz is 20.58 MPa, with a relatively limited increase rate of less than 319%; In addition, the value of tan delta at 23° C. and 1 Hz is 0.447, and the rate of change (calculated based on the value on the 5th day) is only 27.5%, which is negligible.

Both rates of change of these two major rheological parameters well indicate that there is little effect of crystallization delayed over time that can occur in the formulation of Comparative Example 2.

In addition, insufficient changes in initial hardness and properties with time are also evident in the value of change in needle penetration force at 23 DEG C of this adhesive. The needle penetration force was 3dmm at 0 hours (a value indicating a very hard and non-stick adhesive), and after 5 days at room temperature, it was still maintained at 3dmm without any deformation.

Comparative Example 3

The hot melt adhesive of the comparative example shown below was melt-mixed at 185° C. according to the teachings of the prior art, and was prepared using a commercially available polybutene-1 using a Ziegler-Natta catalyst.

Given the above unsatisfactory results obtained from the physical mixing of the two polybutene-1s, as taught by the previous comparative examples and prior art, Comparative Example 3, in accordance with the teachings and components of the prior art, is the only polymer composition An adhesive formulation is prepared by using, as a component, one copolymer of butene-1 and ethylene of the Ziegler-Natta type with a high molecular weight.

It is noteworthy to emphasize that, as already mentioned, the liquid poly-iso-butylene used in the role of plasticizer herein is a completely different material, both from a chemical and structural point of view, from polybutene-1.

Despite the addition of large amounts of plasticizers, waxes and pressure-sensitive adhesive resins, all components of which are low molecular weight and low viscosity, the overall viscosity in the molten state of the above formulation remains too high at 15,370 mPa·s at 170°C, and the ring and end The ball softening point is very high at 157°C.

As can be expected from a material with such a high viscosity, the rheological criterion for good sprayability is the viscous modulus of the adhesive formulation of Comparative Example 3 ( The value of G") is only 163 Pa; or it is not satisfactory because the value of its tan delta is as low as 16.3.

Therefore, the rheological criterion for good sprayability is not fully met; Virtually all attempts to apply by spraying at a temperature of 160°C to 170°C have failed.

As was the case with the previous comparative examples, the inventive comparative formulations cannot be processed by an application process less affected than spraying. Also, in this case, an attempt was made to extrude this formulation as an adhesive coating on a polyethylene film by a slot die at a temperature of 160° C. to 170° C. at a relatively low speed of 250 m/min; In this case, all attempts were unsuccessful.

Also, the open time is too short, only 60 seconds, confirming the difficulty in forming a good and strong adhesive bond after initial contact with the substrate in applying this adhesive.

In addition, the physical properties are very hard and hardly tacky: in fact, the tensile stress at break of the adhesive at 23° C. is a surprisingly high value of 3.94 MPa at 0 hours, and the initial elongation at break is as low as 420%.

The change with time of these physical properties of the adhesive is small, indicating that crystallization delayed with time in all respects of quantitative and qualitative aspects in this formulation based on polybutene-1 of the Ziegler-Natta type insufficiently occurs.

In fact, after standing at 23° C. for 5 days, the tensile stress at break at room temperature increases to 4.15 MPa, and the increase rate is as small as 5%. In contrast, the value of elongation at break decreases to 240%, and the rate of decrease (calculated based on the value at day 5) is only 75%.

In addition, the rheological parameters confirm the poor properties of an adhesive, particularly as an adhesive that crystallizes over time of the hot melt formulation of Comparative Example 3.

In fact, the elastic modulus (G'), which is directly proportional to the hardness of the adhesive at room temperature and at a frequency of 1 Hz already at 0 hours, has a very high value of 2,89 MPa; Also, under the same conditions, the value of the parameter tan delta is as low as 0.238.

Due to the poor crystallization over time of Ziegler-Natta polybutene-1 contained herein, elasticity at room temperature and 1 Hz after 5 days at 23° C., despite the presence of a large amount of polypropylene wax acting as a crystallization nucleating agent The modulus (G') increased only to 2.94 MPa, and the rate of increase was as low as 1.7%.

At this time, the parameter tan delta measured under the same conditions decreased to 0.127, and the rate of change (calculated based on the value on day 5) was 87.4%.

Likewise, due to the excessive initial hardness of the adhesive of the present invention, the needle penetration force at 23° C. is a very low value from 0 hours to 6 dmm, and 5 dmm after standing at room temperature for 5 days, which is a practically negligible change in absolute terms. .

Comparative Example 4

The hot melt adhesive of Comparative Example below was prepared by melt-mixing at 170° C. and using commercially available polybutene-1 synthesized with a Ziegler-Natta catalyst and components and teachings according to the prior art.

The main disadvantages highlighted in the previous comparative examples were poor processability due to excessively high viscosity and unsatisfactory crystallization of the adhesive over time, so the adhesive formulation of Comparative Example 4 was compared to that generally taught by the prior art. Formulated with very low viscosity.

This object was achieved by using a copolymer of butene-1 and ethylene synthesized by a Ziegler-Natta catalyst in which a large amount of both a plasticizer and a pressure-sensitive adhesive resin were combined at a low molecular weight in a particularly low content.

Indeed, some parameters of the adhesive formulation of Comparative Example 4 appeared to be slightly more similar to some optimal characteristics of the adhesive formulation according to the present invention.

For example, the viscosity at 170° C. is 2,650 mPa·s, which is much lower than that of all previous comparative examples; The ring and ball softening point is also as low as 77°C.

Although the open time is also much longer than the previous comparative example at 15 minutes, this value is insufficient to give good processability to the formulation of the present invention in various processes requiring a much longer open time.

However, despite the very low viscosity, the adhesive formulation of Comparative Example 4, similar to that of the Example according to the present invention, - due to the Ziegler-Natta type of polybutene-1 contained essentially at a very high molecular weight - by spraying cannot be processed; All attempts made at 155° C. to 170° C. were unsuccessful. This is also confirmed by the rheological parameters: indeed at 165° C., the value of the viscous modulus (G") corresponding to the value of the elastic modulus (G') of 10 Pa is as low as 180 Pa, i.e. the value of tan delta is only 18, Therefore, it does not meet the minimum requirements of the rheological criteria for acceptable sprayability.

Somewhat surprisingly, particularly due to the low viscosity, the adhesive formulation of Comparative Example 4 exhibited very poor processability even with a slot-die extrusion at a relatively low speed of 250 m/min.

All attempts to extrude a pressure-sensitive adhesive coating at a temperature of 155° C. to 165° C. onto a polyethylene film using this formulation have failed.

Indeed, even these very low viscosity materials are extruded by variable flow in the extrusion die in a very irregular and non-uniform manner, which generates vibrations and undulations in the flow itself. Because of this, it is demonstrated that the extruded adhesive collects as large droplets only in some areas of the substrate, and thus cannot impart a good and stable adhesive bond between the substrates.

In addition, as used herein, polybutene-1 copolymer synthesized with a Ziegler-Natta catalyst having high molecular weight and high viscosity is "dilution" unavoidable, and this type of polymer adheres to polybutene-1 due to crystallization, It is over-diluted with low molecular weight plasticizers and resins without unacceptably aggravating the changes over time in physical and rheological properties.

For example, with respect to the above physical properties, the adhesive of this comparative example has a breaking tensile stress of 0.04 MPa at 23° C., which is very soft at first; After standing for 5 days at room temperature, due to the scarce ability of the Ziegler-Natta type polybutene-1 copolymer, it is sufficiently robust and "perfect" crystallization (especially a dilution that can only be used to lower the adhesive viscosity to an acceptable level). condition), but the tensile stress at break at 23° C. was only 0.56 MPa, indicating that the increase rate was insufficient at 1,300%.

Considering the softness of the adhesive of the present invention, the elongation at break at 0 hours is as high as more than 4,040%, which exceeds the highest full range value measured with the instrument used; It appears to behave apparently similarly to some formulations previously described in accordance with the present invention.

However, due to the rare effect of crystallization delayed with time of the Ziegler-Natta type polybutene-1 used herein, after being left at room temperature for 5 days, the elongation at break is still high and is 1,000%, and therefore, over time The rate of change (calculated based on day 5 values) is only 304%.

This behavior is also evident in the values of the rheological parameters and their changes on standing at room temperature. For example, at a frequency of 23° C. and 1 Hz at 0 hours, the value of the viscous modulus (G′) of the adhesive formulation of Comparative Example 4 is very low as 0.041 MPa, and its tan delta value is 2.33 under the same conditions. .

After standing at room temperature for 5 days, even if the tan delta has an unexpectedly large change with time, it actually has a value of 0.739 after 5 days, so the rate of change (calculated based on the value on day 5) is about 215%. , the same does not occur for the modulus of elasticity (G') at room temperature, the value directly representing the "cure due to crystallization" of the adhesive formulation. In fact, after 5 days at 23° C., the value of the elastic modulus at 23° C. and 1 Hz of the adhesive formulation of Comparative Example 4 is still as low as 0.477 MPa; Therefore, the rate of change was limited to only 1,063%.

This means that although the adhesive formulation of Comparative Example 4 is a very soft material at 0 hours, it is substantially soft even with the lapse of time, that is, the crystallization of the spherical Ziegler-Natta type polybutene-1 included herein is delayed with time. It proves unsatisfactory in terms of both the quantitative and qualitative aspects of the crystals formed.

This is due to the inherently inferior properties of the crystallinity of the high molecular weight polybutene-1 synthesized with the Ziegler-Natta catalyst as used herein; This occurs because of excessive dilution by the resin and large amounts of low molecular weight plasticizers added here to lower the overall melt viscosity, which is the already poor quality characteristic of the time-delayed crystallization of this type of Ziegler-Natta polybutene-1. further aggravate

The needle penetration force at 23 ° C is 119 dmm at 0 hours, and even after standing at room temperature for 5 days, it still reaches a relatively high value of 22 dmm, and the rate of change with time (calculated based on the value at day 5) is 441%.

Examples of adhesive properties

Tables 2, 3 and 4 report some values of the adhesive parameters Peel Strength and Shear Strength, which are measured as described above, at 0 hours and after 5 days at 23° C. and 50% relative humidity, all measured as described above. This value reports that in all three examples according to the invention and in one of the comparative examples it is possible to process and apply the adhesive sufficiently regularly and uniformly only by slot-die extrusion.

Table 2 - Peel Strength for Samples Prepared by Spraying

- Spray temperature: 165℃

- Line speed: 250m/min

- Basis weight of applied adhesive: 1.5g/㎡

Table 3 - Peel Strength for Samples Made by Slot-Die Extrusion

- Extrusion temperature: 165℃

- Line speed: 250m/min

- Basis weight of applied adhesive: 1.5g/㎡

Although the amount of adhesive applied by both spraying and slot die extrusion is very small, only 1,5 g/m 2 , the formulations of the examples according to the invention have values of peel strength suitable for their intended use, for example absorbent hygiene products. as well as indicating, among other things, the value of peel strength over time caused by simple standing at room temperature due to, among other things, the time-delayed optimal crystallization of the low molecular weight isotactic metallocene butene-1 polymer composition contained herein. shows a significant increase.

In contrast, the formulation of the comparative example based on polybutene-1 of the spherical Ziegler-Natta type of high molecular weight and high viscosity, with the exception of Comparative Example 1 in this state-of-the-art application technology, even at a relatively low speed of 250 m/min, It cannot be properly machined by both spraying and slot die extrusion. However, even in this case, the peel strength is low and no increase with time is observed.

However, although not critical at the end use, the value of peel strength at 0 hours is greater for application by slot-die extrusion compared to application by spraying, which indicates the adhesion of the film in the case of application by slot-die extrusion. In addition to the rheological properties of the adhesive according to the invention which promote contact and wetting and partial penetration between the fibers of the nonwoven, it is clearly due to the physical contact and pressure with the extrusion-head which increases the adhesion even at zero hours by helping additional penetration. Needs to be.

Table 4 - Shear Strength for Samples Made with Manual Lab Coater

- Apply with manual lab coater from melt at 170℃

- Adhesive application amount: 50g/㎡

-

The shear strength data from 0 hours to 5 days show particularly clearly the marked effect of the delayed crystallization over time of the formulations of the examples according to the invention.

Thus, as can already be seen from the physical and rheological parameters, these formulations are very soft and tacky materials of low viscosity at 0 hours, and therefore shear under loads of the order of 1 kg or more at a temperature of 40° C., especially under extreme conditions. Although not suitable to pass the strength test, after 5 days of moderate standing, the adhesive can withstand this type of shear strength test for more than 12 hours.

In contrast, the formulations of the comparative examples can be divided into two groups. The first group is the first group of three comparative formulations, apart from using the manual wrap applicator, which are all extremely viscous materials and thus very difficult and practically impossible to process.

Considering these characteristics, the shear strength test at 0 hours and 12 hours was passed; It does not show a more significant increase over time.

In contrast, the formulation of Comparative Example 4 describes a method for lowering the viscosity to an acceptable level by the addition of large amounts of plasticizer and resin using Ziegler-Natta type polybutene-1, and the behavior at 0 hours is seemingly similar to the behavior of the formulations according to the invention; Due to the poor effect of this delayed crystallization of Ziegler-Natta polybutene-1, the shear strength of this material left for 5 days under the given conditions reaches a maximum of 2 hours.

Claims (52)

a) a melt flow rate (MFR) measured at 190° C. under a weight of 2.16 kg in the range of 400 to 2,000 g/10 min;
A) an isotactic butene-1 homopolymer or butene-1 having at least one comonomer selected from ethylene and alpha-olefin having 3 or more carbon atoms, and having a copolymerized comonomer content (C _{A ) of 5 mol% or less} isotactic copolymer,
B) butene-1 isotactic copolymer having at least one comonomer selected from ethylene and alpha-olefin having 3 or more carbon atoms and having a copolymerized comonomer content (C _B ) of 6 mol% to 25 mol% Having a bimodal composition comprising
an isotactic butene-1 polymerizable metallocene composition in which the total content of the copolymerized comonomer is 4 mol% to 18 mol% based on the sum of A) and B); and
b) a hot melt adhesive formulation comprising at least one viscosity modifier that is not solid at room temperature. The method of claim 1,
A hot melt adhesive formulation in which the copolymerized comonomer content (C _A ) of the copolymer A is 4 mol% or less. 3. The method of claim 1 or 2,
A hot melt adhesive formulation wherein the copolymerized comonomer content (C _B ) of the copolymer B is 8 mol% to 20 mol%. The method of claim 1,
A hot melt adhesive formulation wherein the total content of the copolymerized comonomer of the isotactic butene-1 polymerizable metallocene composition is 5 mol% to 15 mol% based on the sum of A) and B). The method of claim 1,
The isotactic butene-1 polymerizable metallocene composition has a hot melt adhesive formulation in which the content of the xylene-soluble fraction at 0° C. is 65% by weight or more based on the total weight of A) and B). The method of claim 1,
The isotactic butene-1 polymerizable metallocene composition has a hot melt adhesive formulation wherein the content of the xylene-soluble fraction at 0° C. is 60% by weight or less based on the total weight of A) and B). 6. The method of claim 5,
The isotactic butene-1 polymerizable metallocene composition is a hot melt adhesive foam comprising 10% to 40% by weight of A) and 60% to 90% by weight of B) based on the total weight of A) and B) emulation. 7. The method of claim 6,
The isotactic butene-1 polymerizable metallocene composition is a hot melt adhesive fabric comprising 35 wt% to 65 wt% of A) and 35 wt% to 65 wt% of B) based on the total weight of A) and B) emulation. The method of claim 1,
The isotactic butene-1 polymerizable metallocene composition has a hot melt adhesive formulation having a ΔH TmII in the range of 3 to 20 J/g as measured by a temperature scanning ramp of 10° C./min. The method of claim 1,
A hot melt adhesive formulation wherein the TmI of the isotactic butene-1 polymerizable metallocene composition is 60° C. or higher. The method of claim 1,
The isotactic butene-1 polymerizable metallocene composition is a hot melt adhesive formulation having a viscosity in the range of 5,000 to 50,000 mPa.s measured at 180°C. The method of claim 1,
A hot melt adhesive formulation wherein the polydispersity of the isotactic butene-1 polymerizable metallocene composition is 4 or less. The method of claim 1,
A hot melt adhesive formulation wherein the Mw value of the isotactic butene-1 polymerizable metallocene composition is 30,000 or more. The method of claim 1,
A hot melt adhesive formulation wherein the glass transition temperature of the isotactic butene-1 polymerizable metallocene composition is -22° C. or less. The method of claim 1,
A hot melt adhesive formulation wherein the yellowness of the isotactic butene-1 polymerizable metallocene composition is less than 0. The method of claim 1,
A hot melt adhesive formulation having a Brookfield viscosity of 5,000 mPa·s or less, measured at a temperature of 170°C. The method of claim 1,
A hot melt adhesive formulation with an open time of 10 minutes or more after cooling from 170°C to 23°C to solidify. The method of claim 1,
A hot melt adhesive formulation with a ring and ball softening point of 120°C or less. The method of claim 1,
The isotactic butene-1 polymerizable metallocene composition constitutes 10 wt% to 85 wt% of the hot melt adhesive formulation. The method of claim 1,
Viscosity modifiers that are not solid at room temperature include paraffinic mineral oil; naphthenic mineral oil; paraffinic and naphthenic hydrocarbons that are not solid at room temperature, and mixtures thereof; non-solid oligomers at room temperature of polyolefins and copolymers thereof selected from non-solid oligomers derived from ethylene, propylene, butene, iso-butylene, and copolymers thereof; plasticizers that are not solid at room temperature formed from esters selected from phthalates, benzoates, and sebacates; vegetable oil; natural and synthetic fats; and mixtures thereof. 21. The method of claim 20,
wherein the viscosity modifier that is not solid at room temperature is a metallocene oligomer of polypropylene or a metallocene oligomer of a propylene-ethylene copolymer. 22. The method of claim 21,
The non-solid viscosity modifier at room temperature is a propylene-ethylene metallocene copolymer having a major molar content of propylene, a softening point of -30°C or less, and a viscosity at 170°C of 300 mPa·s or less. 23. The method according to any one of claims 20 to 22,
wherein said mixture of viscosity modifiers that are not solid at room temperature or a mixture of viscosity modifiers that are not solid at room temperature constitute 5% to 40% by weight of said formulation. The method of claim 1,
A hot melt adhesive formulation further comprising at least one adhesive resin. 25. The method of claim 24,
The pressure-sensitive adhesive resin is an aliphatic hydrocarbon resin and a derivative thereof partially or entirely hydrogenated; aromatic hydrocarbon resins and their partially or fully hydrogenated derivatives; aliphatic/aromatic hydrocarbon resins and their partially or fully hydrogenated derivatives; polyterpenes and modified terpene resins and derivatives of which part or all are hydrogenated; rosin, its esters and partially or fully hydrogenated derivatives; and mixtures thereof. 26. The method of claim 24 or 25,
A hot melt adhesive formulation with a ring-and-ball softening point of 80° C. or higher of the pressure-sensitive adhesive resin or a mixture of the pressure-sensitive adhesive resin. 25. The method of claim 24,
The pressure-sensitive adhesive resin or a mixture of the pressure-sensitive adhesive resin constitutes 15% to 70% by weight of the formulation hot melt adhesive formulation. The method of claim 1,
A hot melt adhesive formulation further comprising up to 5% by weight wax. 29. The method of claim 28,
The wax is a polypropylene wax or a polypropylene wax modified with maleic anhydride, and a hot melt adhesive formulation having a softening point of 120° C. or higher. The method of claim 1,
A hot melt adhesive formulation comprising 15 wt% or less of a polymer chemically different from the isotactic butene-1 polymerizable metallocene composition or one of its components. 31. The method of claim 30,
wherein the polymer is a semi-crystalline copolymer of propylene and ethylene, or a semi-crystalline polymer composition of a copolymer of polypropylene and propylene and ethylene. 32. The method of claim 31,
wherein said copolymer or said polymer composition has a heterophasic morphology. The method of claim 1,
A hot melt adhesive formulation having a monomodal composition and further comprising 15 wt% or less of a homopolymer or copolymer of metallocene isotactic polybutene-1 having an MFR of 200 to 2,000 g/10 min at 190°C. The method of claim 1,
A hot melt adhesive formulation having a value of its viscous modulus (G") corresponding to a value of its modulus of elasticity (G') of 10 Pa at a temperature of 165° C. is at least 200 Pa. The method of claim 1,
When solidified from a molten state while changing from 170° C. to 23° C., the tensile stress at break at a time of 120 minutes or less (defined as “0 hour”) from its solidification at room temperature is 0.25 MPa or less; A hot melt adhesive formulation having a tensile stress at break of 0.7 MPa to 2.5 MPa at 23° C., after standing at 23° C. for 5 days, and in any case greater than at least 1,500% in percentage, based on the same parameters measured at 0 hours . The method of claim 1,
an elongation at break at room temperature of at least 500% in absolute value; After standing at 23°C for 5 days, the elongation at break at 23°C is 100% to 700% as an absolute value, and in any case, as a percentage change value calculated based on the value after 5 days, the percentage relative to 0 hours A hot melt adhesive formulation that is at least less than 500% by percentage change. The method of claim 1,
the elastic modulus (G') at 0 hours at 23° C. and a frequency of 1 Hz is 1 MPa or less; After standing at 23° C. for 5 days, the elastic modulus (G′) measured at 23° C. and at a frequency of 1 Hz is 2 MPa to 10 MPa, and in any case, based on the values of the same parameters as at 0 hours, at least as a percentage Hot melt adhesive formulations greater than 2,000%. The method of claim 1,
tan delta at 0 hours at 23° C. and a frequency of 1 Hz is greater than or equal to 0.25; After standing at 23°C for 5 days, the tan delta at 23°C and at a frequency of 1 Hz is between 0.1 and 0.4, in any case showing a decrease of at least 100% in percentage, based on the value at 0 hours, wherein The percentage reduction is calculated relative to the value at day 5 of the hot melt adhesive formulation. The method of claim 1,
Needle penetration force at 0 hours at 23° C. is 10 dmm or more; A hot melt adhesive formulation having a needle penetration force of 3 dmm to 18 dmm at 23° C. after standing at 23° C. for 5 days, and in any case, a change value of at least 10 dmm as an absolute value, based on the value at 0 hours. The method of claim 1,
After standing for 5 days at 23° C. and 50% relative humidity, the peel strength is at least 0.25 N per 50 mm of width, or alternatively, for the same peel strength measured at 0 hours, the rate of increase in peel strength at day 5 is 30% More than hot melt adhesive formulations. The method of claim 1,
A hot melt adhesive having a shear strength of at least 12 hours after standing at 23° C. and 50% relative humidity for 5 days, or alternatively an increase in shear strength of at least 3 hours at day 5 for the same shear strength measured at 0 hours formulation. a first substrate;
a second substrate; and
A composition comprising the hot melt adhesive formulation of claim 1,
When the first substrate and the second substrate are bonded and applied at a basis weight of 0.5 g/m 2 to 50 g/m 2 , the peel strength of the bonded structure measured after standing at 23° C. for 5 days is greater than 0.25 N per 50 mm of width junction structure. 43. The method of claim 42,
At least one of the two substrates is a porous or fibrous substrate, or a perforated film having a two-dimensional or three-dimensional structure. An absorbent hygiene product comprising the hot melt adhesive formulation of claim 1 . 44. An absorbent hygiene article comprising the bonding structure of claims 42 or 43. 45. The method of claim 44,
Absorbent hygiene products that are baby diapers, training panty diapers, adult incontinence diapers, or feminine sanitary napkins. 47. The method of claim 44 or 46,
The hot melt adhesive formulation,
i) general structural adhesives of said absorbent hygiene products;
ii) for bonding elastic components (threads, ribbons, films or elastic panels);
iii) for enhancing and ensuring the integrity of the absorbent core of an absorbent hygiene article even when in use; and
iv) an absorbent hygiene article used for at least one of the uses for bonding the apertured film into a two-dimensional or three-dimensional structure. An article comprising the hot melt adhesive formulation of claim 1 , wherein the article is an absorbent surgical mattress or sheet, or a medical surgical laminate or wound dressing article. An article comprising the hot melt adhesive formulation of claim 1 , wherein the article is a mattress or a component thereof. An article comprising the hot melt adhesive formulation of claim 1 , wherein the article is packaging. 46. The method of claim 45,
Absorbent hygiene products that are baby diapers, training panty diapers, adult incontinence diapers, or feminine sanitary napkins. 46. The method of claim 45,
The hot melt adhesive formulation,
i) general structural adhesives of said absorbent hygiene products;
ii) for bonding elastic components (threads, ribbons, films or elastic panels);
iii) for enhancing and ensuring the integrity of the absorbent core of an absorbent hygiene article even when in use; and
iv) an absorbent hygiene article used for at least one of the uses for bonding the apertured film into a two-dimensional or three-dimensional structure.