JPS58152009A - Production of tackifying polyolefin - Google Patents

Abstract

PURPOSE:Powdery polyolefin is dipped and dispersed in a specific organic solvent and made to react with a vinyl compound with a polar group under special conditions to produce easily in a short time the titled polyolefin showing high adhesion to the surface of metallic materials. CONSTITUTION:(A) Powdery polyolefin, preferably ethylene homo or copolymer of less than 250 micrometer particle sizes, is dipped and dispersed in (B) an organic solvent that boils at a temperature lower than the melting point under the pressure in the reaction system and does dissolve component A such as acetone. Then, (C) a vinyl compound bearing a polar group, preferably glycidyl acrylate and a radical polymerization initiator such as benzoyl peroxide are added to the above suspension to effect their reaction at a temperature lower than the melting point component A. Further, the temperature is kept to distil off the solvent B from the reaction system to produce the objective polyolefin.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing adhesive polyolefins.

Polyolefins typified by polyethylene and polypropylene do not have polar groups that contribute to adhesion, and therefore do not exhibit any adhesiveness to the surface of metal materials such as the surface of a steel plate. Therefore, attempts have been made to impart adhesive properties to polyolefins by introducing polar groups into polyolefins by chemical or physical methods.

Among these, chemical methods include a method of graft polymerizing a reactive polymer having a polar group to a polyolefin;
Another typical method is to polymerize a hexamer having a polar group into an olefin monomer during olefin polymerization, thereby introducing a polar group into the polyolefin molecule. Among these, the former method is advantageous as an industrial method since it is possible to produce an adhesive polyolefin using a polyolefin obtained by polymerization by a conventional method as a raw material.

The following method has been proposed as an example of a method for graft polymerizing a heptamer having a polar group onto such a polyolefin.

(1) A method in which polyethylene is dissolved in an alkyl aromatic hydrocarbon solvent, maleic acids are added thereto by a specific addition method, and then the maleic acids are graft copolymerized in the presence of a radical polymerization initiator (Japanese Patent Publication No. 52-197) 396
Publication No. 36).

(2) A method in which a powdered polyolefin and maleic anhydride are brought into contact in the absence of a liquid medium, and graft copolymerization is carried out using a radical polymerization initiator at a temperature lower than the melting temperature of the polyolefin (Japanese Unexamined Patent Application Publication No. 1983-1999- 77493).

(3) A radical polymerization initiator is attached to the surface of polypropylene or propylene copolymer powder in advance, and this powder is immersed in an organic solvent solution (one that does not dissolve polypropylene and the radical polymerization initiator) in which Shitsummer is dissolved. A method of graft copolymerizing a hexamer by suspending the suspension and carrying out a radical polymerization reaction (Japanese Unexamined Patent Publication No. 49-76989).

(4) A method in which a copolymer of conjugated diene and ethylene is used as a raw material polyolefin, and a powder of this copolymer is graft copolymerized with a vinyl monomer using a radical polymerization initiator in a poor solvent (Japanese Patent Publication No. 51 -24319 Publication) -0 (5) A powdered he-olefin polymer is mixed with a vinyl monomer having an epoxy group and a radical polymerization initiator, and the mixture is heated in a substantially dry state to perform grafting. Method of polymerization (Japanese Patent Publication No. 55-32722).

Among these methods, method (1) allows effective grafting, but requires a step to precipitate and take out the polyethylene once dissolved, and also requires a large amount of organic solvent, so it is not preferred in terms of efficiency. I can't say that. Also (2
Methods ) to (5) require a long time to achieve sufficient grafting, require the addition of a special step similar to (1), or are difficult to achieve due to the grafting of the polyolefin powder. There are also problems such as difficulty in achieving sufficient adhesion in the modified polyolefin produced because it is difficult to apply it uniformly on the surface, and it has not been necessarily satisfactory as a method for industrial implementation.

The present invention provides a method for producing a modified polyolefin powder with excellent adhesive properties by uniformly grafting polar groups on the surface of a polyolefin powder in a simple operation and in a short time. With the goal.

The above object is to immerse and disperse a powdered polyolefin in an organic solvent which has a boiling point lower than the melting point of the polyolefin and which does not substantially dissolve the polyolefin, and to form a vinyl compound having a polar group and radical polymerization. The reaction is carried out in the presence of an initiator at a temperature lower than the melting point of the polyolefin, and the reaction is further continued at a temperature lower than the melting point of the polyolefin, and the organic solvent is distilled out of the reaction system from the raw material. This can be achieved by the present invention, which comprises a method for producing an adhesive polyolefin characterized by the following.

Next, the present invention will be explained in detail.

The method of the present invention relates to an improvement in a method in which a monomer having a polar group is graft-copolymerized on the surface of a polyolefin powder that is dispersed without being dissolved in a solvent and is substantially in a powder state. It is. However, in the method of the present invention, the grafting reaction of polyolefin powder is
The reaction described above is carried out while substantially distilling off the reaction solvent, and the reactant solution in which the monomer and radical polymerization initiator are uniformly dissolved in a very concentrated state is in uniform contact with the surface of the polyolefin powder. This method is characterized by uniformly producing a graft copolymer with a high grafting rate on the surface of a polyolefin powder by intentionally performing a distillation operation.

The polyolefin used in the present invention is not particularly limited, but preferable examples include ethylene homopolymers and copolymers such as high-pressure polyethylene, medium-pressure polyethylene, and ethylene/vinyl acetate copolymers. Particle size is 60 mesh or less (250pm
The polyolefin may preferably contain a small amount (approximately 10 to 500 ppm) of an antioxidant such as a phenolic antioxidant or other additives such as a stabilizer.

The vinyl compound having a polar group to be graft-polymerized to the polyolefin is not particularly limited as long as it can react with the polyolefin through a radical reaction and impart adhesiveness to the polyolefin, but preferred examples include acrylic acid and Acrylic acid derivatives such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and glycidyl acrylate; methacrylic acid, and methyl methacrylate, ethyl methacrylate, butyl methacrylate, and 2-ethyl acrylate. Examples include methacrylic acid derivatives such as ethylhexyl and glycidyl methacrylate; and maleic acid and maleic acid derivatives such as maleic anhydride. Among these vinyl compounds having a polar group, particularly preferred examples include vinyl unsaturated carboxylic acids having an epoxy group in the molecule, such as glycidyl acrylate and glycidyl methacrylate.

The vinyl compound having a polar group is usually used in an amount of 2 to 40% by weight based on the raw material polyolefin. A more preferred proportion is 5 to 20% by weight.

The radical polymerization initiator is not particularly limited as long as it efficiently generates active radicals capable of causing a hydrogen abstraction reaction at a temperature of 100° C. or lower, but examples thereof include:
Mention may be made of benzoyl peroxide, di-t-butyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, and azobisisobutyronitrile. The radical polymerization initiator is usually used in a proportion of 0.01 to 5% by weight based on the raw material polyolefin.

The organic solvent used in the reaction is an organic solvent (dispersion medium) that has a boiling point lower than the melting point of the raw material polyolefin and does not substantially dissolve the polyolefin. In general, it has a boiling point of 90"0 or less under the atmospheric pressure in the reaction vessel, and hardly dissolves the polyolefin powder to be modified even under heating.
On the other hand, an organic solvent is used that is sufficiently soluble in the vinyl compound having a polar group and the radical polymerization initiator and does not adversely affect the grafting reaction. Such an organic solvent can be arbitrarily selected depending on the reaction system to be used. For example, when carrying out the reaction at normal pressure using maleic anhydride as the vinyl compound and benzoyl peroxide as the radical polymerization initiator, acetone, methyl acetate, ethyl acetate, etc. can be used as the organic solvent for the reaction. It is advantageous to use

The organic solvent used in the reaction is preferably used in an amount of 1 to 5 mM based on the raw material polyolefin Ig, and a particularly preferable range is 1.5 to 3 mIL based on the raw material polyolefin Ig. There is no particular problem in using an excessive amount of the organic solvent beyond the above range, but in that case, the reaction time for distilling off the organic solvent becomes longer.
Moreover, such methods are generally not suitable for industrial practice, as there is no particular advantage to using such an excess amount of reaction solvent; on the other hand, if the amount of organic solvent used is slightly less than the above range, In some cases, it is possible to achieve the purpose of the present invention even when the polyolefin is used, but if the amount used is very small compared to the raw material polyolefin,
It becomes difficult to uniformly graft the surface of the olefin powder,
This is not preferable because it tends to fail to impart sufficient adhesiveness to the modified polyolefin.

Examples of reaction operations for carrying out the method of the invention are shown below.

The raw material polyolefin powder to be modified, the vinyl compound, and the radical polymerization initiator are placed in a reaction vessel together with a dispersion medium. The reaction vessel is preferably a vessel equipped with a nitrogen gas introduction pipe and a stirring device and whose temperature can be adjusted. Furthermore, instead of providing a stirring device, it is also preferable to use a reaction vessel in which the reaction vessel itself can rotate to stir the contents, such as a rotary evaporator.

Place the inside of the reaction vessel under nitrogen gas flow, and while sufficiently stirring the contents inside the vessel, heat the reaction vessel to a temperature near or above the boiling point of the dispersion medium (however, at a temperature below 15°C below the melting point of the raw material polyolefin). ) and allow the reaction to proceed while distilling off the dispersion medium. The reaction is continued until the dispersion medium is almost completely removed from the reaction system, and the reaction is completed. It is thoroughly washed with a solvent that well dissolves the vinyl compound homopolymer produced as a by-product, such as the above-mentioned dispersion medium, and dried.

In the above method, the present invention allows the reaction to continue until the dispersion medium is almost completely distilled off from the reaction system, without separating and recovering the polyolefin under reaction from the dispersion medium during the distillation of the dispersion medium. According to the research of the present inventors, the grafting reaction of powdered polyolefins is particularly important when a certain amount of dispersion medium is present in the reaction system.
It was found that the disease progressed rapidly. Specifically speaking,
The dispersion medium is 0.5 to 0 per powder polyolefin Ig.
, 02 mJl, especially in an amount within the range of 0.2 to 0.02 mM, and when the dispersion medium is being reduced under heating, the grafting reaction proceeds rapidly. On the other hand, in a reaction system in which the proportion of the dispersion medium coexisting with the powder polyolefin is out of the above range, the rate of the desired grafting reaction will be extremely slow.

Furthermore, when the ratio of the dispersion medium to the polyolefin powder is within the above range, the grafting reaction occurs uniformly on the surface of the polyolefin powder, resulting in the uniform introduction of polar groups onto the surface of the polyolefin powder. , greatly contributes to improving the adhesion of polyolefin powder.

The polyolefin powder obtained by using the above-mentioned method under the above-mentioned conditions is a modified polyolefin powder in which a vinyl compound having a polar group is almost uniformly graft-copolymerized on its surface. The grafting rate, that is, the ratio of the vinyl compound graft-copolymerized to the polyolefin powder, is usually in the range of 10-5 to 10-1 g equivalent/100 g of polyolefin powder.

The modified polyolefin produced by the method of the present invention is
The appearance of the powder is almost the same as that of the polyolefin powder used as a raw material. However, its adhesion to the surface of metal materials is significantly improved compared to the raw material polyolefin (which has virtually no adhesion), and it appears to exhibit particularly high adhesion to the surface of steel plates. become.

As described above, in the method of the present invention, highly adhesive grafted polyolefin powder can be prepared in a relatively short period of time (polyolefin powder is placed in a dispersion medium, without distilling off the dispersion medium, and under normal suspension conditions). Compared to the method of imparting adhesiveness to polyolefins through a grafting reaction, the time required to impart the same degree of adhesiveness is approximately 1/10), and a special addition step is not required. Since it can be produced without any additives, it is very advantageous as an industrial method for imparting adhesive properties to polyolefin powder.

Next, the implementation of the present invention will be described.

[Example 1] 20g of low density polyethylene powder (average particle size: 100~
2507zm), 0.5g maleic anhydride, 0.87
g of benzoyl peroxide and 30 CC of acetone (dispersion medium) were charged to a rotary evaporator. This suspended mixture was heated at 90°C while stirring under nitrogen gas flow.
The reaction time was 60 minutes (the time required in step 1 from the start of the reaction to the end of the dispersion medium distillation operation). The amount of acetone remaining after that was 0.045 mfL/g of polyethylene powder.

After thoroughly washing the reaction product with warm acetone, it was dried in a vacuum environment, and polyethylene was recovered in a powder state. The grafting rate of the obtained polyethylene powder was O,0
0.11 g equivalent/100 g of polyethylene powder.

1 g of this grafted polyethylene powder was sprinkled uniformly onto a steel plate (50 mm x 70 mm x 3 mm, sanded with No. 240 sandpaper and degreased with trichlorethylene) heated to 170°C, and a 1 mm thick polyethylene sheet was placed over it. After preheating this for 2 minutes, 10
A sample for adhesion evaluation was prepared by applying a load of 0 g/crrf for 3 minutes. When the 180' vinyl strength of this sample was measured using a Tensilon type tensile strength tester (measurement temperature: 23°C), an adhesive strength of 5.2 kg/Cm was recorded.

[Example 2] A grafted polyethylene powder was produced in the same manner as in Example 1, except that 2 g of glycidyl methacrylate was used instead of 0.5 g of maleic anhydride. The amount of acetone remaining after the completion of the reaction was 0.045 ml/g of polyethylene powder, and the grafting rate of the obtained polyethylene powder was 0.058 g equivalent/1°Og of polyethylene powder.

Example 1 using 1 g of this grafted polyethylene powder
A sample for adhesion evaluation was prepared in the same manner as above, and the 180' vinyl strength was similarly measured (measurement temperature = 2).
3° C.) and an adhesive strength of 9.2 kg/cm was recorded.

[Example 3] Grafted polyethylene powder was produced in the same manner as ÷ Example 2 except that the reaction time was changed to 20 minutes. The amount of acetone remaining after the reaction was 0.1 mJl/1 g of polyethylene powder. The grafting rate of the obtained polyethylene powder was 0.042 g equivalent/100 g of polyethylene powder.

Example 1 using 1 g of this grafted polyethylene powder
A sample for adhesion evaluation was prepared in the same manner as above, and the 180° building strength of this sample was similarly measured (measurement temperature: 2
3° C.) and an adhesive strength of 5.9 kg/cm was recorded.

[Example 4] Grafted polyethylene powder was produced in the same manner as in Example 2 except that the reaction time was changed to 30 minutes. The amount of acetone remaining after the reaction was 0.08 mm/g of polyethylene powder. The grafting rate of the obtained polyethylene powder was 0.049 g equivalent/100 g of polyethylene powder.

Example 1 using 1 g of this grafted polyethylene powder
A sample for adhesion evaluation was prepared in the same manner as above, and the 180° building strength of this sample was similarly measured (measurement temperature: 2
3° C.) and an adhesive strength of 8.0 kg/cm was recorded.

[Example 5] Grafted polyethylene powder was produced in the same manner as in Example 2 except that the amount of dispersion medium used was changed to 40 cc.The amount of acetone remaining after the completion of the reaction was 0°046
mJl/1 g of polyethylene powder, and the grafting rate of the obtained polyethylene powder was 0.056 g.
The equivalent weight was 100 g of polyethylene powder.

Example 1 using 1 g of this grafted polyethylene powder
A sample for adhesion evaluation was prepared in the same manner as above, and the 180' vinyl strength was similarly measured (measurement temperature: 2).
3° C.) and an adhesive strength of 9.0 kg/cm was recorded.

[Example 6] Grafted polyethylene powder was produced in the same manner as in Example 2 except that the amount of dispersion medium used was changed to 20 cc.The amount of acetone remaining after the completion of the zero reaction was 0.041 m
JL/1 g of polyethylene powder, and the grafting rate of the obtained polyethylene powder was 0.055 g equivalent/100 g of polyethylene powder.

Example 1 using 1 g of this grafted polyethylene powder
A sample for adhesion evaluation was prepared in the same manner as above, and the 180' vinyl strength was similarly measured (measurement temperature: 2).
3° C.) and an adhesive strength of 8.7 kg/cm was recorded.

[Example 7] Grafted polyethylene powder was produced in the same manner as in Example 2 except that the amount of glycidyl methacrylate used was changed to Ig. The amount of acetone remaining after the completion of the zero reaction was as follows:
0.45 mg/1 g of polyethylene powder, and the grafting rate of the obtained polyethylene powder was 0.0
The amount was 25 g equivalent/100 g of polyethylene powder.

Example 1 using 1 g of this grafted polyethylene powder
A sample for adhesion evaluation was prepared in the same manner as above, and the 180' vinyl strength was similarly measured (measurement temperature: 2).
3° C.) and an adhesive strength of 5.7 kg/cm was recorded.

[Example 8] A grafted polyethylene powder was produced in the same manner as in Example 2 except that the amount of glycidyl methacrylate used was changed to 4 g. The amount of acetone remaining after the reaction is
0.45 m/g of polyethylene powder, and
The grafting rate of the obtained polyethylene powder was 0.09
The amount was 7 g equivalent/100 g of polyethylene powder.

Example 1 using 1 g of this grafted polyethylene powder
A sample for adhesion evaluation was prepared in the same manner as above, and the 180° building strength of this sample was similarly measured (measurement temperature: 2
3°C) and an adhesive strength of 8.0 kg/cm was recorded.

[Example 9] A grafted polyethylene powder was produced in the same manner as in Example 2 except that the amount of benzoyl peroxide used was changed to 0.34 g. The amount of acetone remaining after the reaction is
0.45 mJ1/g of polyethylene powder, and the grafting rate of the obtained polyethylene powder was 0.0
The amount was 30 g equivalent/100 g of polyethylene powder.

Example 1 using 1 g of this grafted polyethylene powder
A sample for adhesion evaluation was prepared in the same manner as above, and the 180° building strength was measured in the same manner (measurement temperature = 2).
3°C) and an adhesive strength of 5.7 kg/cm was recorded.

[Example 10] A grafted polyethylene powder was produced in the same manner as in Example 2 except that the amount of benzoyl peroxide used was changed to 1.0 g. The amount of acetone remaining after the reaction is 0
．． 45mJ1/tg of polyethylene powder, and
The grafting rate of the obtained polyethylene powder was 0.05
The amount was 4'g equivalent/100g of polyethylene powder.

Example 1 using 1 g of this grafted polyethylene powder
A sample for adhesion evaluation was prepared in the same manner as above, and the 180° building strength of this sample was similarly measured (measurement temperature: 2
3° C.) and an adhesive strength of 8.2 kg/Cm was recorded.

Applicant for the watch Ube Industries Co., Ltd. Agent Patent attorney Yasuo Yanagawa Continued Amendment Written on March 17, 1981 Haruki Shimada, Commissioner of the Patent Office 2 Title of the invention Process for producing adhesive polyolefin 3 Relationship to the case of the person making the amendment Patent applicant 4 Agent 6 Number of inventions increased by amendment None 7 [Claims column] and [Detailed description of the invention -] of the specification subject to amendment 8゛ Contents of amendment Description as attached We will amend the "Detailed Description of the Invention" column as follows.

The organic solvent has a boiling point of the reaction system (2) line 15 of the same page, (3) Line 18 of the same page Under atmospheric pressure → Under atmospheric pressure (normal pressure, reduced pressure, or increased pressure) Claims (correction) A temperature lower than the melting point of the polyolefin in the presence of a vinyl compound having a polar group and a radical polymerization initiator, which is immersed and dispersed in an organic solvent that exhibits a boiling point lower than the melting point of the polyolefin and does not substantially dissolve the polyolefin. A method for producing an adhesive polyolefin, which comprises reacting at a temperature lower than the melting point of the polyolefin, and distilling off the organic solvent from the reaction system while continuing the reaction at a temperature lower than the melting point of the polyolefin.

2. The method for producing an adhesive polyolefin according to claim 1, wherein the vinyl compound having a polar group is a vinyl unsaturated carboxylic acid having an epoxy group.

Claims (1)

[Claims] 1. Powdered polyolefin is immersed and dispersed in an organic solvent that has a boiling point lower than the melting point of the polyolefin and does not substantially dissolve the polyolefin, and a vinyl compound having a polar group; Radical - React in the presence of a polymerization initiator at a temperature lower than the melting point of the polyolefin, and further 1. A method for producing an adhesive polyolefin, which comprises distilling the organic solvent out of the reaction system while continuing the reaction at a temperature lower than the melting point of the polyolefin. 2. The method for producing an adhesive polyolefin according to claim 1, wherein the vinyl compound having a 2° polar group is a vinyl unsaturated carboxylic acid having an epoxy group.