JPH0134452B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention is a method of undercoating molded products made of polyolefin such as polypropylene, or automobile bumpers made of polypropylene and synthetic rubber, etc., to improve the adhesion of paint, etc. to the surface thereof. The present invention relates to a method for producing a surface treatment agent comprising a modified polyolefin solution suitable for use as a treatment agent. [Prior art] Paints, other resins, molded products, etc. are formed on the surface of polyolefin molded products such as polypropylene to increase the added value, but molded products made of polyolefin have a polarity. Since it is small and has poor adhesion to general paints, it is known to improve the adhesion of the surface of polyolefin molded products by subjecting them to chromic acid treatment, flame treatment, solvent treatment, etc. in advance. However, these methods are time-consuming due to complicated processing, are dangerous because they use corrosive chemicals, and require strict process control to provide stable adhesion. So,
It has become a technology that is almost never seen again. Furthermore, in JP-A-48-20824, a polypropylene polymer is modified by chemically bonding an alicyclic carboxylic acid having a cis-type double bond in the ring or its anhydride in the presence of a radical generator. After merging,
A method of molding or a method of molding a polypropylene polymer and chemically bonding the alicyclic carboxylic acid or its anhydride to the surface of the molded product is disclosed. However, the former method is economically disadvantageous because it is necessary to bind the carboxylic acid or the like to the polypropylene polymer of the entire molded article to modify the surface of the molded article. Furthermore, the latter method is not suitable for practical use because the processing steps are complicated and require a long time. On the other hand, the method of treating the surface of the molded product with an undercoat provides adhesion with a simple operation and takes a short time, so it has the advantage of being able to be placed on a series of lines that are continuous with the painting process. be. Several proposals have also been made regarding processing agents for use in such undercoating. For example, Japanese Patent Publication No. 44-958 discloses a treatment solution in which an amorphous polypropylene polymer modified with a specific proportion of maleic acid or its anhydride is dissolved in a solvent. The term "amorphous polypropylene polymer" as used herein refers to polymers and copolymers sometimes referred to as atactic polypropylene containing at least about 20 mol% propylene units, which are copolymers of propylene and at least one comonomer. It is an amorphous polymer consisting of substances. In addition, there is a similar treatment agent disclosed in JP-A-49-10890, in which amorphous polyolefin is treated with an alicyclic carboxylic acid or an α,β-unsaturated carboxylic acid having a cis-type non-conjugated double bond in the ring. Alternatively, a surface treatment agent containing a modified polyolefin obtained by chemically bonding the anhydride of the carboxylic acid is disclosed. This amorphous polyolefin is also a non-crystalline polymer. It is true that when these treatment agents are used, the adhesion between the molded article and the paint is improved, but as time passes thereafter, the adhesion performance deteriorates. Furthermore, the surface of the molded product after being coated with these treatment agents tends to become sticky and uneven in thickness, and the smoothness of the coating film after coating is also unfavorable. On the other hand, the present applicant has already proposed in JP-A-48-20844 a method in which a halogenated hydrocarbon solution of rubber or an addition polymer resin having a polar group is used as a surface treatment agent, and a polyolefin molded article is immersed in the solution. . This method has been applied to molded products of polyethylene, polypropylene, etc., and is used for miscellaneous goods, containers, automobile parts, fibers, nonwoven fabrics, etc. as molded products with excellent paint adhesion. On the other hand, as a method of dissolving a polyolefin in an organic solvent and grafting an unsaturated carboxylic acid, for example, in Japanese Patent Publication No. 15422/1973, 10 to 50 parts of maleic anhydride is added to 100 parts of highly crystalline polypropylene. In addition, a method is disclosed in which the temperature is raised to dissolve the polymer and maleic anhydride, and then peroxide is dropped into the reaction system. However, this method tends to produce a homopolymer of maleic anhydride as a side reaction, and because the polymer is crystalline, modified polypropylene that dissolves in organic solvents at room temperature, which is the gist of the present invention, cannot be produced. I can't. In addition, in Japanese Patent Publication No. 52-39636, maleic acids are added to polyethylene in an alkyl aromatic hydrocarbon solvent in the presence of a radical initiator per gram of polyethylene.
A method of feeding at a rate of 10 ^-5 to 10 ^-2 mol/hr is disclosed. The modified polyolefin obtained by this method is also a modified product of highly crystalline polyethylene, so it is difficult to dissolve in organic solvents at room temperature.
-15422, it is possible to charge the organic peroxide before the reaction, but as explained in detail later in the specification, organic peroxide can be added to the reaction system in this way. The method of supplying ethylene-α-
Due to the gelation of the olefin copolymer, solvent insoluble matter and a homopolymer of unsaturated carboxylic acid monomers (which are also insoluble in carbon-hydrogen organic solvents) are formed, so they are uniformly applied to the solvent targeted by the present invention. A modified polyolefin suitable for the dissolved surface treatment solution cannot be obtained. [Problems to be Solved by the Invention] In recent years, there has been an even higher demand for paint adhesion performance in molded products for automobiles, and there has also been a demand for simplification and cost reduction of the processing steps. To simplify the process, it is desirable that the surface treatment liquid be one that can be applied with a sprayer, but some conventional treatment liquids require a high concentration of modified polymer to obtain sufficient adhesion, and the viscosity of the treatment liquid It was difficult to use a sprayer because of the high Furthermore, in conventional methods, when graft copolymerizing polyolefin with maleic anhydride or the like to obtain a surface treatment liquid, the solution viscosity of the polyolefin increases, and therefore, the coating method is limited to dipping treatment. In addition, surface treatment liquids using halogenated polyolefins do not have sufficient adhesion for the base coating film, and since the base treatment liquid requires heating and baking once applied, the introduction of halogen causes problems with the treatment liquid. There are also problems with stability. Therefore, the present inventor solved these problems and
As a result of intensive research into a surface treatment liquid that can be dissolved at room temperature, has excellent paint adhesion, can be applied by spraying, and can be used in practical use in a simple manner that does not require the baking process of the base coating, the present application was completed. It came to this. [Means for solving the problem] The present inventor has developed ethylene-α with a specific ethylene content.
- When performing graft modification using an olefin copolymer by adding an unsaturated carboxylic acid or its derivative and an organic peroxide to a solution of the copolymer in an organic solvent, it is necessary to It has been found that by controlling the amount of organic peroxide supplied within a specific range, it is possible to obtain a surface treatment liquid that is soluble in organic solvents and meets the above objectives. That is, the present invention has an ethylene content of 10 mol% or more.
When adding an unsaturated carboxylic acid or its derivative and an organic peroxide to an organic solvent solution of less than 50 mol% ethylene-α-olefin copolymer and carrying out a grafting reaction under stirring and heating conditions, the organic The solvent is an aromatic hydrocarbon, and ethylene-α
-The polymer concentration during the modification reaction of the olefin copolymer is 10 to 1000 g/-Total reaction solvent and heating temperature are in the range of 100 to 200°C, and the ethylene-
The ethylene content x (mol%) in the α-olefin copolymer and the added amount y (mmol/mmol/
-Total reaction solvent) is within the range of formula (1), and when the supply time of organic peroxide to the reaction system is T ₁ (hr), the parameter regarding the supply rate of organic peroxide is expressed by formula ( 2) is satisfied, and the amount of unsaturated carboxylic acid supplied to the reaction system is adjusted to z (mmol/-
surface treatment consisting of a graft-modified polyolefin solution characterized in that the parameter regarding the supply rate of unsaturated carboxylic acid satisfies the condition of formula (3) when the supply time is T ₂ (hr) and the total reaction solvent) The invention relates to a method for producing the agent. [Ethylene-α-olefin copolymer] The ethylene-α-olefin copolymer, which is the raw material for the modified polymer, has an ethylene content of 10 mol%.
It is necessary to use a copolymer with a content of at least 50 mol%. More preferably the ethylene content is 15
Ethylene-α-olefin random copolymer having an ethylene content of from 50 mol % to 50 mol %, particularly preferably an ethylene content of
When 20 to 50 mol% of the ethylene-propylene random copolymer is used, a high quality product can be obtained as the surface treatment liquid of the present invention. If a copolymer with an ethylene content of less than 10 mol % is used as an ethylene-α-olefin copolymer, the crystallinity is too high, so only a modified polymer that is insoluble in organic solvents is obtained, and the surface that is the object of the present invention cannot be obtained. Processing liquid is difficult to obtain. On the other hand, if an ethylene-α-olefin copolymer with an ethylene content of 50 mol% or more is used, the viscosity of the resulting modified product tends to increase, and furthermore, cross-linked products tend to form and are highly crystalline. Since the amount of essentially insoluble polymer increases, it is not suitable as a spray-type surface treatment liquid. The molecular weight of the ethylene-α-olefin copolymer is preferably from 1.0 to 10, particularly from 1.5 to 5 in terms of intrinsic viscosity [η] (measured in decalin at 135°C, dl/g). If [η] is too low, the cohesive force of the modified product will be too low, and when used as a surface treatment liquid, the adhesive force with paint etc. will tend to decrease.
If [η] is too high, the viscosity of the surface treatment solution will be too high, making it difficult to use for spraying, so it is preferably within the above range. When an ethylene-propylene random copolymer is used, one having a crystallinity of 0 to 30%, particularly 0 to 20% is preferred. This is to improve the solubility of the modified product in organic solvents. [Reaction solvent] Organic solvents for dissolving these ethylene-α-olefin copolymers include benzene, toluene,
Aromatic hydrocarbons such as xylene, cymene, and cymene can be used, and alkyl-substituted aromatic hydrocarbons are particularly preferred. [Unsaturated carboxylic acid or its derivative] Examples of the unsaturated carboxylic acid to be used include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, and citraconic acid. In addition, as derivatives of unsaturated carboxylic acids, acid anhydrides, esters,
There are amides, imides, metal salts, etc., such as maleic anhydride, citraconic anhydride, itaconic anhydride,
Methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, glycidyl acrylate, glycidyl methacrylate, monoethyl maleate, diethyl maleate, monomethyl fumarate, fumaric acid Dimethyl ester, itaconic acid monomethyl ester, itaconic acid diethyl ester, acrylamide, methacrylamide, maleic acid monoamide, maleic acid diamide, maleic acid-N-monoethylamide,
Maleic acid-N,N-diethylamide, Maleic acid-N-monobutyramide, Maleic acid-N,N
-dibutylamide, fumaric acid monoamide, fumaric acid diamide, fumaric acid-N-monoethylamide,
Fumaric acid-N,N-diethylamide, fumaric acid-
Examples include N-monobutylamide, fumaric acid-N,N-dibutylamide, maleimide, N-butylmaleimide, N-phenylmaleimide, sodium acrylate, sodium methacrylate, potassium acrylate, potassium methacrylate, etc. . Among these, it is most preferred to use maleic anhydride. [Organic peroxide] In addition, the organic peroxides used include benzoyl peroxide, dichlorobenzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(peroxy benzoate) hexyne-3,1,
4-bis(tert-butylperoxyisopropyl)benzene, lauroyl peroxide, tert-
Butyl peracetate, 2,5-dimethyl-2,
5-di(tert-butylperoxy)hexyne-
3,2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, tert-butyl perbenzoate, tert-butyl perphenylacetate, tert-butyl perisobutyrate, tert-butyl per-sec-octoate , tert-butyl perpivalate, cumyl perpivalate and tert
-Butylperdiethyl acetate and others (Here, R is an alkyl group having 1 to 3 carbon atoms). Among these, di-tert-butyl peroxide is particularly preferred. Note that an azo compound such as azobis-isobutylnitrile, dimethyl azoisobutyrate, etc. can also be used in addition to or together with the organic peroxide. Furthermore, the copolymer is modified in an organic solvent,
When using the obtained reaction solution as a spray coating solution by diluting it with the same or other organic solvent or adjusting the concentration of the modified polymer to 10 to 100 g per 1 part organic solvent without diluting, It is preferable to use organic peroxides whose decomposition products are relatively low boiling point substances, such as di-tert-butyl peroxide, tert-butyl peroxyisobutyrate, tert-butyl peroxy octate, etc. . This is because when such an organic peroxide is used, the decomposed products of the radical generator can also be removed by volatilization in the drying process to remove the organic solvent after spraying the modified polymer solution as a surface treatment liquid. This is because the adhesion with the paint becomes even more excellent. [Graft Reaction Conditions] Next, preferred reaction conditions for the graft reaction will be explained. 10 to 1000 g, preferably 50 to 500 g, particularly preferably 100 to 400 g of the raw material ethylene-α-olefin copolymer is dissolved in 1 part of the organic solvent to supply an unsaturated carboxylic acid or its derivative and an organic peroxide. This can be carried out under stirring and heating. Unsaturated carboxylic acids or their derivatives and organic peroxides have formulas (2) and (3)
It is preferable to add them sequentially and at the same speed while satisfying the following conditions. The amount of organic peroxide supplied y (mmol/-total reaction solvent) depends on the ethylene content x (mol%) of the ethylene-α-olefin copolymer to be subjected to the modification reaction, and it is necessary to satisfy the following formula: . Furthermore, it is preferable that the following formula is satisfied. Here, in the above equation

[Application to surface treatment liquid]

In order to apply the modified polyolefin solution provided by the present invention to the application of a surface treatment liquid (including use as an adhesive), the reaction solution may be diluted as is or with the same or different solvent as the reaction solvent. After isolating and purifying the modified ethylene-α-olefin copolymer from the reaction solution, the modified ethylene-α
-Polymer concentration of olefin copolymer from 5 to 5
It may be adjusted to 150g/, especially within the range of 10 to 100g/. If the polymer concentration is less than 5 g/min, the resulting base coat will be too thin and it will be difficult to obtain sufficient adhesion;
If the amount exceeds 150 g/l, the solution becomes viscous, which tends to cause uneven thickness of the base coating film that is formed, impairing the smoothness and uniformity of the surface after coating. Polyolefin molded articles to which the surface treatment liquid is applied can be molded by various melt molding methods, and various polyolefins can be used as raw materials. Specifically, there are high-pressure polyethylene, medium-low pressure polyethylene, polypropylene, poly-4-methyl-pentene-1, poly-butene-1, polystyrene, and copolymers such as ethylene-propylene copolymer and ethylene-propylene. Examples include butene copolymers, propylene-butene copolymers, and mixtures thereof can also be used. These polyolefins contain talc, zinc oxide,
The adhesion of the paint is particularly good when glass fibers, titanium white, inorganic fillers such as magnesium sulfate, pigments, etc. are blended. The polyolefin may contain additives such as stabilizers, ultraviolet absorbers, and hydrochloric acid absorbers. Preferably used stabilizers are 2,6-di-
tert-butyl-4-methylphenol, tetrakis [methylene (3,5-di-tert-butyl-4-
hydroxyhydrocinnamate)] methane, metaoctadecyl-3-(4'-hydroxy-3,5'-
di-tert-butylphenyl) propionate,
2,2'-methylenebis(4-methyl-6-tert-
butylphenol), 4,4′-butylidenebis(3-methyl-6-tert-butylphenol),
4,4'-thiobis(3-methyl-6-tert-butylphenol), 2,2-thiobis(4-methyl-6-tert-butylphenol), 1,3,5-
Trimethyl-2,4,6-tris (3,5-di-
Phenolic stabilizers such as tert-butyl-4-hydroxybenzyl)benzene, 1,3,5-tris(2-methyl-4-hydroxy-5-tert-butylphenol)butane, dilaurylthiodipropionate, These include sulfur-based stabilizers such as stearyl thiodipropionate, and phosphorus-based stabilizers such as tridecyl phosphite and trinonylphenyl phosphite. Preferably used UV absorbers include 2-hydroxy-4-octoxybenzophenone, 2-ethylhexyl-2-cyano-
These include 3,3-diphenyl acrylate and paraoctylphenyl salicylate. Further, a preferably used hydrochloric acid absorbent is calcium stearate. Moreover, this surface treatment liquid is particularly suitable for spray coating on polyolefin molded articles. Further, the temperature of the treatment liquid during treatment is not particularly limited, but the paint adhesion can be sufficiently exhibited at room temperature. Furthermore, after applying the surface treatment liquid, simply drying naturally for a short period of time (for example, 5 to 10 minutes) without baking the base coat will provide sufficient adhesion for practical use even when paint is applied. It has good performance. A polyolefin molded product whose surface has been treated with this surface treatment liquid is coated with a paint by a method such as electrostatic painting, spray painting, or brush painting. These paints may be applied by applying a primer coat and then a top coat. Although not limited to the paint used,
If a coating film with particularly high paint adhesion is required, solvent-based thermoplastic curable acrylic resin paints, solvent-based thermosetting acrylic resin paints, acrylic modified alkyd resins, epoxy resin paints, and polyurethane paints can be used. preferable. Polyolefin molded products coated with these paints are cured using conventional methods such as nichrome wire, infrared rays, and high-frequency heating, but the curing conditions vary depending on the material, shape, and properties of the polyolefin molded product. You can decide. The coating film of the polyolefin molded product obtained by this surface treatment method has excellent smoothness, and the durable adhesion of the coating film is particularly improved. [Example] Example 1 Propylene-ethylene copolymer (ethylene content 30 mol%, [η] 2.16 crystallinity 12% at 135°C for decalin) 300 as the raw ethylene copolymer
g. 900 ml of toluene as a solvent was charged into an autoclave, and nitrogen was blown into the system to purge the system with nitrogen. After raising the temperature of the system to 145°C and completely dissolving the raw material polymer in the solvent, 55.4 g of maleic anhydride and 17.5 g (120 mmol) of ditertiary butyl peroxide (DTBPO), each dissolved in 50 ml of toluene, were added. They were continuously added dropwise to the system from separate feed ports at the same speed over a period of 4 hours. Furthermore, as a post-reaction
After continued stirring at 145° C. for 2 hours, the system was cooled to room temperature. To this modified solution, 7 toluene was further added and mixed, resulting in a uniform polymer content of 3wt/vol% at room temperature.
A polymer solution A was obtained. In addition, the parameters Q, R, and S in this experimental example are each 1.02,
It was 0.26, 0.20. On the other hand, polypropylene (Mitsui Petrochemical Polypropylene)
A sheet (50 mm x 50 mm x 1 mm) was obtained by injection molding. The surface treatment agent obtained above was spray-coated onto this sheet at room temperature by an air spray method, and the sheet was left to dry at room temperature for about 5 minutes. Thereafter, an acrylic resin paint diluted approximately 1:1 with thinner was spray-coated onto each sheet in the same manner, and the sheets were placed in an air oven and baked at 100°C for 30 minutes to dry. After each sheet obtained was left at room temperature for 24 hours, the following tests were conducted. However, for the peel test, use a knife to make stripes at 1 mm intervals vertically and horizontally on the painted surface of the sheet.
100 grids were made, adhesive tape (Nichiban Cello Tape) was placed on top of these, and adhesion was evaluated by the number of grids remaining when the adhesive tape was peeled off. [Initial Adhesion] Each sheet was directly subjected to a peel test. [Water Resistance] After each sheet was immersed in hot water at 40°C for 240 hours, a peel test was conducted. [Volatile Oil Resistance] Each sheet was immersed in petroleum benzine at 25°C for 24 hours, and then a peel test was conducted. As the acrylic paint, Rekrac 55 manufactured by Fujikura Kasei was used. These results are shown in Table 1. Example 2 1 for 100 ml of the denaturation solution obtained in Example 1
of acetone was added to precipitate the polymer, and a modified copolymer was obtained. The obtained cake was further washed repeatedly with acetone and then vacuum-dried at room temperature for one day to obtain a purified modified copolymer.
The maleic anhydride content in this purified modified polymer is
6.5wt%, [η] was 0.50. To 3 g of this purified modified polymer, 1 part of toluene was added and mixed to obtain a homogeneous polymer solution B at room temperature with a polymer content of 3 wt/Vol%. Using this surface treatment liquid B, a coating test was conducted in the same manner as in Example 1. Table 1 shows the results.
It was shown to. Comparative Examples 1 and 2 Propylene was produced in the same manner as in Example 1, except that the amounts of peroxide (diterbutyl peroxide) supplied to the system were 4.2 g (29 mmol/) and 60 g (411 mmol/), respectively. Ethylene copolymer was modified with maleic anhydride. As a result, although the maleic anhydride content in the purified modified polymers remained unchanged at 6.5 wt%, these reaction solutions were diluted with toluene to make the polymer content 3 wt/vol%. However, in both cases, insoluble portions were present, and a uniform polymer solution could not be obtained. Note that the values of the parameter Q in this comparative example were 0.24 and 3.4, respectively, which were out of the range shown in claim 1. Polypropylene coatings were prepared using the surface treatment solutions C and D adjusted to 3 wt/vol% in the same manner as in Example 1. Table 1 shows the measurement results of various physical properties. Examples 3 and 4, Comparative Examples 3 to 6 Except for using an ethylene-α-olefin copolymer having the physical properties shown in Table 1 as the modified raw material,
In the same manner as in Example 1, a graft reaction in toluene, dilution of the reaction solution with toluene, and a polypropylene coating test were conducted. The results are shown in Table 1. Example 5 A modified solution was obtained in the same manner as in Example 1, except that dicumyl peroxide was used instead of tert-butyl peroxide as the organic peroxide. Furthermore, a modified polymer was once isolated from this modified solution in the same manner as in Example 2, and this was redissolved in toluene to prepare a surface treatment solution, and a coating test was conducted. The results are shown in Table 1. Example 6 An ethylene-propylene random copolymer grafted with maleic anhydride was prepared in the same manner as in Examples 1 and 2 by using p-xylene instead of toluene as a reaction solvent for the graft reaction. The obtained modified copolymer was redissolved in toluene in the same manner as in Example 2 to obtain a surface treatment liquid. The results of the coating test are shown in Table 1. Comparative Examples 7 and 8 The reaction temperature of the graft reaction was 90 and 210°C, respectively.
A surface treatment solution was prepared in the same manner as in Example 1, except for the following. The results of the coating test are shown in Table 1. Comparative Examples 9 and 10 Same as Example 1 except that the organic peroxide was supplied to the reaction system for 20 minutes (Comparative Example 9) or the maleic anhydride was supplied for 20 minutes (Comparative Example 10) The reaction, preparation of a surface treatment solution, and coating test were conducted using the method described above. The results are shown in Table 1. Example 7, Comparative Examples 11 and 12 Modified ethylene copolymer was produced in the same manner as in Example 1, except that the ethylene-α-olefin copolymer shown in Table 1 was used as the modified raw material and the modification reaction was carried out under the reaction conditions shown in Table 1. A surface treatment liquid made of a polymer (polymer concentration was 70 g/-toluene) was prepared.
A coating test was conducted in the same manner as in Example 1, except that a urethane paint (Utanal L manufactured by Ohashi Chemical Co., Ltd.) was used instead of the acrylic paint. The results are shown in Table 1.

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Claims (1)

[Claims] 1. An unsaturated carboxylic acid or a derivative thereof and an organic peroxide are added to an organic solvent solution of an ethylene-α-olefin copolymer having an ethylene content of 10 mol% or more and less than 50 mol%, and the mixture is stirred. When carrying out the graft reaction under heating conditions, the organic solvent is an aromatic hydrocarbon, and the polymer concentration during the modification reaction of the ethylene-α-olefin copolymer is 10 or more.
1000g/- total reaction solvent, heating temperature 100 or more
200°C, and the ethylene content x (mol%) in the ethylene-α-olefin copolymer and the added amount y (mmol/-total reaction solvent) of the organic peroxide are expressed by the formula (1) and the parameter regarding the supply rate of organic peroxide when the supply time of organic peroxide to the reaction system is T ₁ (hr) is expressed by equation (2). In addition, the amount of unsaturated carboxylic acid supplied to the reaction system is z (mmol/-total reaction solvent).
The parameters related to the supply rate of unsaturated carboxylic acid when the supply time is T ₂ (hr) are expressed as
(3) A method for producing a surface treatment agent comprising a graft-modified polyolefin solution, which satisfies the following conditions. 2 The ethylene-α-olefin copolymer is
The method according to claim 1, wherein the ethylene-propylene random copolymer has an ethylene content of 20 to 50 mol%. 3. The production method according to claim 1, wherein the organic peroxide is di-tert-butyl peroxide. 4. The production method according to claim 1, wherein the unsaturated carboxylic acid or its derivative is maleic anhydride, and the amount of maleic anhydride grafted onto the polymer is in the range of 0.5 to 15% by weight. 5. The production method according to claim 2, wherein the ethylene-propylene random copolymer has a crystallinity of 0 to 30%.