JPH0461025B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a polymer composition. More specifically, the present invention relates to a method for producing a polymer composition that has improved heat resistance without substantially impairing the desirable properties of ethylene polymers. [Prior art] Ethylene-based polymers such as ethylene-unsaturated carboxylic ester copolymers, ethylene-vinyl ester copolymers, and ethylene-unsaturated carboxylic acid copolymers have traditionally been used as base polymers for hot melt adhesives and sealants. copolymers are widely used. Although these ethylene copolymers have good compatibility with other polymers and exhibit excellent properties such as adhesion to substrates, flexibility, and cold resistance, they are not always satisfactory in terms of heat resistance. Not yet. In order to improve the heat resistance of these ethylene copolymers, copolymers with a low comonomer content or low melt index are sometimes used, especially in the field of hot melt adhesives. However, there are disadvantages such as decreased compatibility with other polymers and poor applicator workability. In addition, when preparing compositions with improved heat resistance using these ethylene copolymers as base polymers, attempts have been made to incorporate additives such as high softening point waxes and tackifying resins. There is. However, in order to improve heat resistance, such additives must be incorporated in fairly large amounts, and as a result, the adhesion, low-temperature properties, etc. of the composition are impaired. [Problems to be Solved by the Invention] An object of the present invention is to improve the heat resistance of an ethylene copolymer without substantially impairing its desirable properties, and to improve the heat resistance of the ethylene copolymer so that it can be suitably used as a hot melt adhesive or a sealant. It is an object of the present invention to provide a method for producing a polymer composition that can be used. [Means for Solving the Problems] The polymer composition of the present invention that achieves the above object comprises a. 95 to 50% by weight of the polymer and b having a melting point higher than the melting point of component a;
In a polymer mixture consisting of 5 to 50% by weight of a peroxide-decomposed olefin polymer having a melt viscosity of 10,000 cps or less at 180°C, at least one of the components a and b is a polymer component to be graft-modified. Forming a mixture of polymers graft-modified with d-unsaturated carboxylic acid or its acid anhydride in an amount of 5 parts by weight or less per 100 parts by weight, and 0.01 to 3 parts by weight per 100 parts by weight of the polymer mixture. It is produced by melt-kneading with c organic peroxide. Examples of the ethylene-unsaturated carboxylic acid ester copolymer as an ethylene copolymer include ethylene and ethyl acrylate, butyl acrylate,
Examples include copolymers with methyl methacrylate, hexyl acrylate, and the like. Examples of the ethylene-vinyl ester copolymer include copolymers of ethylene and vinyl acetate, vinyl propionate, and the like. In addition, examples of ethylene-unsaturated carboxylic acid copolymers include ethylene and acrylic acid,
Examples include copolymers with methacrylic acid and the like. Among these ethylene copolymers, ethylene-
Taking ethyl acrylate copolymer and ethylene-vinyl acetate copolymer as examples, the ethylene content is about 95-50% by weight, and the melt index (MI;
dg/min) of about 10 to 1000. If the ethylene content is above this range, it will not exhibit satisfactory properties in terms of flexibility, adhesiveness, etc. On the other hand, if the ethylene content is below this range, the compatibility with component b will decrease. Regarding the melt index, when melt-kneaded in the presence of organic oxides, the crosslinking reaction of the ethylene copolymer proceeds easily, so when considering applications such as hot melt adhesives, the melt index is relatively low. It is preferable to use one with a high index. As a peroxide decomposable olefin polymer,
Examples include polypropylene, propylene-ethylene copolymer, polybutene-1, butene-1-ethylene copolymer, poly-4-methylpentene-1, and the like. In these polymers, it is necessary to copolymerize about 50 mol% or more of peroxide-decomposable components such as propylene, butene-1, and 4-methylpentene-1; If the proportion is too high, a crosslinking reaction of the copolymer itself will occur, resulting in only a significant increase in melt viscosity, and no effect of improving heat resistance will be obtained. Furthermore, the melting point of these peroxide-decomposed olefin-based polymers must be higher than the melting point of the ethylene-based copolymer of component a, and if one with a lower melting point is used, the present invention The desired effect of improving heat resistance cannot be obtained. Furthermore, it is desirable that the peroxide-decomposed olefin polymer has a relatively low melt viscosity, and if one with a melt viscosity of 10,000 cps or less at 180°C is used, it will be sufficiently kneaded with component a in a short period of time. It has the advantage of improving heat resistance even when added in a relatively small amount. If a material with a melt viscosity higher than this is used, kneading with component a tends to be insufficient, making it considerably difficult to obtain the desired effects of the present invention. In the polymer component consisting of component a and component b, component a is 95 to 50% by weight, and component b is 5 to 50% by weight.
It is used in proportions of % by weight. If component b is used in a proportion higher than this, the composition will not be able to maintain the properties of component a in terms of flexibility, adhesiveness, etc. On the other hand, if the proportion used is lower than this, the effect of improving the heat resistance of the composition will be insufficient. You won't be able to see it. Examples of organic peroxides include dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di-tert-butylperoxy)hexane, and 2,5-dimethyl-2,5-di(tertiary-butyl peroxide). butylperoxy)hexyne-3,1,3-bis(tert-butylperoxyisopropyl)benzene,
1,1-bis(tert-butylperoxy)-3,3,
5-trimethylcyclohexane, n-butyl-
4,4-bis(tert-butylperoxy)valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, Tertiary butyl mill peroxide and the like can be mentioned. These organic peroxides are generally used in an amount of 0.01 to 3 parts by weight per 100 parts by weight of the polymer component. In the adhesive composition according to the present invention, at least one of the polymer components consisting of component a and component b is graft-modified with component d, an unsaturated carboxylic acid or its acid anhydride, and the composition contains such a graft-modified product. The polymer components are melt kneaded with the organic peroxide in the following manner. (1) d component graft modification a component [(a') component] - b
Component - c component (2) a component - d component graft modification b component [(b')
Component]-c component (3) d component graft modification a component [(a') component]-d
Component Graft modification component b [component (b')] - component c Unsaturated carboxylic acids or acid anhydrides thereof used for graft modification include, for example, maleic acid, fumaric acid, itaconic acid, acrylic acid, methacrylic acid, and croton. Acids such as maleic anhydride and itaconic anhydride are used, and maleic anhydride, which is difficult to undergo radical polymerization by itself, is particularly preferred. These unsaturated carboxylic acids or their acid anhydrides are used in an amount of 5 parts by weight per 100 parts by weight of the polymer to be graft-modified.
It is used in proportions of parts by weight or less. From the relationship between the actual grafting rate and adhesive strength, the grafting rate is approximately 3 to 5.
Since the adhesive force reaches saturation at a percentage by weight, graft modification at a higher graft ratio is not preferable from a cost standpoint. The graft modification reaction is
It is carried out according to a conventional method using 0.01 to 3 parts by weight of organic peroxide per 100 parts by weight of polymer. The preparation of the polymer composition comprises the a or a′ component,
b' component and c component are melted using a Banbury mixer, kneader, extruder, etc., so that the polymer component consisting of a or a' component and b or b' component is melted, and the organic filtrate as component c is melted. After melting and kneading the oxide under temperature conditions that sufficiently decompose the oxide, it is formed into powder, flakes, pellets, rods, etc. What is important in preparing the polymer composition of the present invention is to have both components a or a' and b or b' coexist and to melt-knead them in the presence of an organic peroxide as component c. Only then can the object of the present invention be achieved. On the other hand, peroxide-decomposed component b or b' is melt-kneaded with component c, component b or b' is split and decomposed, and then this decomposition product and component a or a' are simply melted together. A polymer composition with excellent heat resistance cannot be obtained only by kneading. The polymer composition of the present invention can be prepared into a hot-melt adhesive by blending a tackifier resin, wax, plasticizer, filler, antioxidant, etc. thereto as required. As the tackifier resin, for example, rosin or its derivatives, terpene resin, terpene-phenol resin, aromatic, aliphatic, alicyclic or copolymer petroleum resin, coumaron-indene resin, styrene resin, etc. are used. In terms of compatibility and adhesiveness, terpene resins and alicyclic petroleum resins are particularly preferred, and in terms of heat resistance, terpene resins are particularly preferred; Parts by weight are used, preferably about 50 to 150 parts by weight. In addition, waxes used as adhesive viscosity reducing agents include, for example, paraffin wax, microcrystalline wax,
Polyethylene waxes, polypropylene waxes, and the like are generally used in amounts up to about 50 parts by weight per 100 parts by weight of the polymer composition. Furthermore, when preparing a polymer composition, within a range that does not impair the desired properties,
For purposes such as compatibility, flexibility and viscosity control, a
An olefin polymer having a lower melting point than the other components can also be used in combination. [Effects of the Invention] The polymer composition according to the present invention maintains good flexibility and adhesiveness and also exhibits heat resistance improved by about 20 to 25°C, so it can be used in hot melt adhesives, sealants, etc. It can be effectively used as In addition to this, extrusion molding method, injection molding method,
It can also be processed into blown films, cast films, extrusion coated products, pipes, various injection molded products, various hollow molded products, etc. by compression molding. [Example] Next, the present invention will be explained with reference to an example. Note that the melt viscosity is a measured value at 180°C. Reference example 1 Ethylene-ethyl acrylate copolymer (ethyl acrylate content 25% by weight, MI210, melting point 65°C)
After kneading 70 parts (by weight, the same below) and 30 parts of low molecular weight polypropylene (melting point 135°C, melt viscosity 40cps) at 170°C using a laboplasto mill, 2.
0.8 part of 5-dimethyl-2,5-bis(tert-butylperoxy)hexyne-3 was added, and the temperature was raised to 200° C. while kneading. Melt-kneading was continued at this temperature for an additional 10 minutes to prepare a polymer composition. Reference Example 2 In Reference Example 1, the same amount of another low molecular weight polypropylene (melting point 155°C, melt viscosity 5000 cps) was used. Example 1 100 parts of the ethylene-ethyl acrylate copolymer used in Reference Example 1, 1.5 parts of maleic anhydride, and 30.2 parts of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexyne were added. A maleic anhydride graft-modified ethylene-ethyl acrylate copolymer was produced by melt-kneading at 200°C using a Labo Plastomill. In a similar manner, the low molecular weight polypropylene used in Reference Example 1 was modified by maleic anhydride grafting. In the preparation of the polymer composition of Reference Example 1, each of the above-mentioned maleic anhydride graft modified products was used in place of each polymer component in the same amount (70 parts and
30 copies). Example 2 In Reference Example 1, the same amount of the maleic anhydride graft modified low molecular weight polypropylene of Example 1 was used in place of the low molecular weight polypropylene. Example 3 In Reference Example 2, the same amount of the maleic anhydride graft-modified ethylene-ethyl acrylate copolymer of Example 1 was used instead of the ethylene-ethyl acrylate copolymer. Regarding the polymer compositions prepared in each of the above examples, MI (load 2160 g, temperature 190°C) and shear adhesive failure temperature were measured as follows, and the obtained results are shown in the table below. Ta. (Measurement method of shear adhesive failure temperature) A 1 mm thick sheet made from a polymer composition is cut into 15 mm wide strips, the strips are sandwiched between two pieces of kraft paper, and the temperature is adjusted using a heat sealer. Heat sealing was carried out under the conditions of 180° C., pressure of 1 Kgf/cm ² and time of 5 seconds to bond. A sample with a width of 25 mm is prepared from this adhesive, a load of 200 g is applied to it, and the temperature is increased at a rate of 0.3°C/min, and the rate at which the load falls is measured. 【table】

Claims (1)

[Claims] 1 a) 95 to 50% by weight of an ethylene-unsaturated carboxylic acid ester copolymer, ethylene-vinyl ester copolymer or ethylene-unsaturated carboxylic acid copolymer and b having a melting point higher than the melting point of component a;
In a polymer mixture consisting of 5 to 50% by weight of a peroxide-decomposed olefin polymer having a melt viscosity of 10,000 cps or less at 180°C, at least one of the components a and b is a polymer component to be graft-modified. A mixture of a polymer graft-modified with d-unsaturated carboxylic acid or its acid anhydride is formed in an amount of 5 parts by weight or less per 100 parts by weight, and the polymer mixture is added in an amount of 0.01 to 3 parts by weight per 100 parts by weight. A method for producing a polymer composition, which comprises melt-kneading it with c. an organic peroxide.