JPS6358195B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates generally to pressure-sensitive calenderable adhesives, particularly those based on thermoplastic rubbers having improved strength properties, processability and significant tack, adhesion and low creep properties. This relates to adhesives such as those mentioned above. As is known in the art and has been practiced in the industry, various types of organic, synthetic, polymeric materials such as triblock copolymers, such as styrene-diolefin-styrene type materials, From commercially available materials in the form of isoprene-styrene and styrene-butadiene-styrene triblock copolymers, fairly effective pressure-sensitive adhesives, hereinafter referred to as PSAs, can be prepared. The former type is generally preferred for use as a contact adhesive, and the latter type is preferably used as a heat-activated adhesive. Generally, the base elastomeric materials used in adhesive formulations, whether synthetic or natural rubber, are not cross-linked and are therefore soluble in the common solvents used in adhesive manufacturing. It is. Although it has essentially amorphous properties, the strength and other important properties characterizing the product when mixed with other conventional additives may be inadequate for the adhesion problem at hand. many. Recent advances in polymer technology have made it possible to produce resin materials that are highly transparent and have extremely high strength. The above for producing partially curable or non-curable thermoplastic rubbers, represented by crystalline homo- and copolymers of ethylene and propylene, and elastic alpha-olefin copolymers. Polymers of the type are disclosed in US Pat. US Pat. No. 4,072,735 discloses a hot melt adhesive based on ethylene-propylene rubber, a viscous resin and a large amount of polybutylene. In the present invention, the polymer composition of a thermoplastic "crystalline" olefin polymer component combined with an elastic olefin copolymer component has a variety of advantageous properties, particularly viscosity. It has been found that it can be used to produce pressure-sensitive adhesives having good adhesion, creep properties, etc., and easy calendering properties. It is therefore a primary object of the present invention to provide an adhesive composition having the above-mentioned properties and other improved properties, the adhesive produced being resistant to heat, humidity, physical stress, etc. Suitable for use in widely varying environments under a variety of conditions. It has significantly improved properties. Ethylene and CH ₂ = CHR (where R is at least 1
an elastomeric copolymer with at least one other copolymerizable monoolefin having the formula (alkyl having 1 to 12 carbon atoms) with or without a copolymerizable polyene; The above objects can be achieved by the present invention, which provides a calenderable composition of pressure-sensitive adhesive, which composition contains from 10 to 10 parts by weight of the elastic copolymer.
100 parts by weight of crystalline polypropylene, and a tackifier in an amount sufficient to provide a weight ratio of tackifier to elastomeric copolymer of from 1.2:1 to 8:1. Contains. Additionally, the present invention provides an adhesive having a composition coated onto a substrate, such as a flexible film-forming polymeric material containing a thermoplastic resin such as polyethylene or polyester. A significant advantage of the present invention is that compositions comprising the above-described elastic and crystalline polymeric components exhibit the highly desirable strength characteristic of typically crystalline thermoplastic polymeric materials and the typically elastic, essentially amorphous It is possible to provide an effective adhesive that combines the easy processability and excellent viscosity, adhesion and creep properties characteristic of polymeric materials. The use of thermoplastic polymeric materials with a high degree of crystallinity in adhesive compositions, even in significant amounts as indicated herein, usually renders the materials inert and insoluble; Forbidden. Therefore, the "thermoplastic rubber" and tackifier described herein can be effectively molded as described herein to produce a highly adhesive product. It was unexpected that it would be manufactured. Elastic copolymers are disclosed in U.S. Pat. No. 3,758,643, no.
No. 3806558 or No. 3835201, and the elastic copolymer mixed with the crystalline polymer is partially cured or not cured. can also obtain the improvements of the present invention. The three US patents mentioned above are incorporated herein by reference. In U.S. Pat. No. 3,758,643, an amorphous elastomeric copolymer is composed of two or more monoolefins having the formula CH ₂ =CHR, where R is alkyl having 1 to 12 carbon atoms. It is produced by copolymerizing. A small amount of at least one copolymerizable polymer may be added to create unsaturation in the copolymer. The polyene may be a conjugated diene or preferably a non-conjugated diene such as dicyclopentadiene described in US Pat. No. 3,758,643. Furthermore, trienes as well as dienes can be used. Polyene can be used up to 20% by weight of the copolymer rubber. As noted in column 3 of this patent, partial curing of elastic copolymers carried out by conventional agents of free radical or cross-linking type results in gel or insoluble content, when measured in cyclohexane. at least 10%, preferably at least 20% more than the initial gel content of the rubber
%, more preferably at least 30%. Generally, the gel content is at least 30
% but not more than 90%, gel is a part of the rubber that is insoluble in cyclohexane by soaking a sample of the material in the solvent for 48 hours at 73°C (22.8°C), taking an aliquot of the solution, and It is measured by determining the concentration of solute by evaporating it. The partially cured rubber is mixed with a crystalline polymeric material, such as polypropylene, on the roll mill of a Ban-bury mixer or extruder. As noted in the patent, highly crystalline isotactic or syndiotactic forms of polypropylene are somewhat superior. As noted in U.S. Patent No. 3,806,558,
By carrying out partial curing of the rubber in the presence of the crystalline polymer component, with mixing and mastication, the above process can be converted into a one-step process. As described in U.S. Patent No. 3,835,201,
It is unnecessary to treat copolymer rubbers with drugs if they have special rheological properties, in particular a fairly high value of the viscosity parameter, called "zero shear viscosity". . The latter, also called steady flow viscosity, is defined as the melt viscosity at zero shear rate and can be determined from stress relaxation or shear creep values in a manner as fully described in US Pat. No. 3,835,201. The above-mentioned patent further indicates a "branching index" as an aptitude test. In any case, the above-mentioned U.S. Pat. No. 3,758,643,
Any of the thermoplastic rubber compositions described in Nos. 3,806,558 and 3,835,201 may be advantageously used in the present invention. Tackifiers that can be used in the present invention include hydrocarbon resins such as amorphous polypropylene; commercially available polyterpenes such as Wingtack 10 and Wingtack 95 from Gutdeyer; Hydrogenated rosin esters such as those commercially available from Hercules Co. under the names Permalyn-xA
There are zinc salts of rosin acid, such as the glycerin or pentaerythritol esters of rosin acid, commercially available from Hercules Co., Ltd. under the names -115 and Foral 85; and Pexate resin, commercially available from Hercules Co., Ltd.
The above-mentioned tackifiers are available in different grades, differing in, for example, molecular weight, softening point, etc. In any case, the characteristics of the adhesive produced will vary somewhat depending on the nature and amount of tackifier used. In particularly preferred embodiments of the invention, two or more tackifiers are used in combination. Particularly effective combinations include different polyterpenes, especially commercially available polyterpenes with approximately equal amounts of Wingtak 10 and Wingtak 95, and in weight ratios such as 83:71, 82:99.
and 62:134 hydrogenated rosin ester (Harcolin D) and polyterpene (Wingtak 95). The tackifier has a tackifier:elastic copolymer weight ratio of about 1.2:1 to 8. :1, particularly in an amount in the range of about 1.2:1 to 6:1, more preferably 1.5:1 to 4.5:1.This composition of the invention combines the thermoplastic rubber material and the tackifier. can be conveniently obtained by mixing on a rubber roll machine, the rolls being heated at high temperatures, e.g.
Preheated to 275-350〓 (135-177℃). If mixing is carried out, the temperature of the rolls is approximately 200
It is preferable to reduce the temperature to 175°C (79.5°C) or less, for example, 175°C (79.5°C) or less. The resulting adhesive composition can be applied to a suitable substrate by pressing the composition to a desired thickness, for example, between a Mylar film and a piece of release paper to form an adhesive. . Alternatively, the thermoplastic rubber and a small amount of tackifier may be mixed in a Banbury roll machine and then the remaining tackifier is added on the rubber roll machine to complete the preparation. Since the adhesive compositions of the present invention are easily calenderable, conditioning on a rubber roll machine is greatly facilitated. The above examples are given by way of illustration only and are not intended to limit the invention. Amounts given in the examples are by weight unless otherwise noted. Example 1 The thermoplastic rubber (TPR) used in this example contains 90 parts partially cured ethylene propylene copolymer rubber (masterbatch) and 10 parts crystalline polypropylene blended therein. . Example 1 of U.S. Pat. No. 3,758,643,
This is the substance listed in Test No. 4. On a rubber roll machine with the rolls preheated to 310°C (154.5°C), mix 200 parts of the above TPR, 250 parts of Wingtack 95 and 250 parts of Wingtack 10. As the level of tackifier increases during mixing, reduce the temperature of the rolls to 170㎓ (76.6°C). A sample of the final mixture containing 72% by weight of tackifier was placed between a Mylar film and a piece of release paper at 170%
(76.6°C) to obtain a film with a thickness of approximately 2 mils. The produced adhesive has a Probe Tack Value of 720 (100g load,
0.1 seconds). Examples 2, 3 and 4 The TPR used in this example is
No. 3758643, Example 1, Test No. 8, containing 70 parts (masterbatch) of partially cured ethylene-propylene copolymer blended with 30 parts of crystalline polypropylene.
A series of adhesives is produced by first mixing TPR and a small amount of tackifier together on a rubber roll machine, and finishing the conditioning by adding the remaining tackifier on a rubber roll machine. Product composition and Mylar film 2.3 mil, 1.9 mil and 1.6
The physical properties obtained when coating each with a mil thickness are shown below:

[Table] Example 5 The TPR used in this example is the TPR shown in U.S. Pat. Contains ethylene propylene copolymer. The adhesives produced as in Examples 2 to 4 had the following compositions. Ingredients TPR 100 Wingtack 10 88 Wingtack 95 78 Adhesive applied to Mylar backing at a thickness of 2.2 mils when tested as described in the examples above. The following values are shown. Viscosity 202 Adhesion to Steel 40 Creep Properties 66 Example 6 The TPR used in this example is the TPR described in U.S. Pat. Contains an 80:20 blend with polypropylene. An adhesive of the following composition is prepared as described in Examples 2-4: Ingredients TPR 100 Wingtack 10 77 Foral 85 66 The above composition with a thickness of 3.2 mils is prepared as described in the previous example. When tested as described in , the following results are obtained. Adhesion to steel: 78 oz 1 inch (2211.3 g 12.54 cm or 870.6 g 1 cm) Flat bar creep time: 72 hours 10.5 inch (1.27
cm) Repeating the method described in the above example using other tackifiers and the materials described in this example and varying the concentrations within the above limits, A similar result is obtained.

Claims (1)

[Claims] 1. Ethylene and the formula CH ₂ =CHR (R is 1 carbon atom
and at least one other copolymerizable monoolefin represented by ~12 alkyl groups), with or without at least one copolymerizable polyene, said elastic copolymer Contains 10 to 100 parts by weight of crystalline polypropylene and a tackifier per 100 parts by weight, and the weight ratio of the tackifier to the elastic copolymer is 1.2:1.
8:1. 2. The pressure-sensitive adhesive composition as set forth in claim 1, wherein the tackifier is at least one selected from the group consisting of hydrocarbon resin, polyester pen, rosin ester, and zinc salt of rosin acid. . 3. The pressure-sensitive adhesive composition according to claim 2, wherein the tackifier is a glycerin ester of rosin acid. 4. The pressure-sensitive adhesive composition according to claim 2, wherein the tackifier is a pentaerythritol ester of rosin acid. 5. The pressure-sensitive adhesive composition according to claim 2, wherein the tackifier is polypropylene with a difficult to define shape. 6. The pressure-sensitive adhesive composition according to claim 2, wherein the tackifier is a hydrogenated rosin ester. 7 The ratio of tackifier to copolymer with elasticity is
A pressure sensitive adhesive composition according to any one of claims 2 to 6, wherein the ratio is 1.2:1 to 6:1. 8. Claim 7, wherein the ratio of tackifier to elastic copolymer is from 1.5:1 to 4.5:1.
Pressure-sensitive adhesive compositions described in Section. 9. The pressure-sensitive adhesive composition according to any one of claims 1 to 8, wherein the amount of crystalline polymer is 20 to 67% by weight of the elastic copolymer. 10 The above elastic copolymer has a gel content of at least
10. The pressure-sensitive adhesive composition according to claim 1, wherein the pressure-sensitive adhesive composition is partially cross-linked so that 30% is 90% or less. 11. The pressure-sensitive adhesive according to any one of claims 1 to 10, wherein the elastic copolymer has a zero shear viscosity determined from a shear creep value at 130° C. of at least 1×10 ⁹ poise. agent composition. 12. The pressure-sensitive adhesive composition according to any one of claims 1 to 11, wherein the copolymerizable monoolefin is propylene. 13 A claim in which the elastic copolymer is an unsaturated terpolymer of ethylene, propylene, and at least one copolymerizable non-conjugated diene in a small amount to 20% by weight based on the elastic copolymer. The pressure-sensitive adhesive composition according to any one of items 1 to 11. 14. The pressure-sensitive adhesive composition according to claim 13, wherein the non-conjugated diene is dicyclopentadiene.