JPS58187406A - Production of adhesive polyolefin - Google Patents

Abstract

PURPOSE:Grafting is effected between a polyolefin and a specific amount of maleic acid in a specific solvent in the presence of a radical initiator to produce a polyolefin of high adhesion economically. CONSTITUTION:The grafting of maleic acid onto polyolefin is effected in a solvent such as benzene or halogenated aromatic hydrocarbon, e.g., monochlorobenzene using 10-300pts.wt. of a polyolefin per 1,000pts.wt. of the solvent and 0.01-2.0pts.wt. of maleic acid per 100pts.wt. of the polyolefin where the groups of maleic acid reach 0.01X10<-4>-0.5X10<-4>mol/gram of the polyolefin, in the presence of 0.2-2.0pts.wt. of radical initiator of diisopropyl peroxide.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a modified polyolefin by grafting maleic acids onto a polyolefin. More specifically, by grafting maleic acids onto polyolefin.

The present invention relates to a method for obtaining polyolefins with excellent adhesive properties by improving the adhesive properties of polyolefins without losing the inherent properties of polyolefins.

Polyolefins have excellent mechanical properties as well as optical, electrical, and chemical properties, but as they are completely non-polar substances, they have poor affinity with other substances.
In particular, it is poor in adhesiveness, and to improve this, it is already well known that polyolefins are grafted with maleic acids to impart adhesiveness. As a modification method, a method of grafting reaction in a solution state (for example, Japanese Patent Publication No. 44-15
Various methods are known, such as a method of performing a graft reaction in a molten state (Japanese Patent Publication No. 43-27421, etc.).

In the method of grafting in a solution state to produce a polyolefin with good adhesive properties, alkyl aromatic hydrocarbons such as badruene, xylene, and ethylbenzene cucumene are most suitable for use in the reaction.

It is said that modified polyolefins with good adhesion cannot be produced by grafting reactions using solvents such as benzene, monochlorobenzene, and dichlorobenzene (Tokukō 5).
However, as mentioned by the inventors of the same application, compared to grafting reactions using benzene, monochlorobenzene, dichlorobenzene, etc. as solvents, grafting reactions using alkyl aromatic hydrocarbons as solvents In this case, the reaction rate of the grafted maleic anhydride is extremely low (at most 10 units of maleic anhydride subjected to the reaction can be added to the polyolefin), which is not economical.

As for the cause of this problem, the inventors of the same application found that the modified polyolefin produced in a solvent such as chlorobenzene exhibits an extremely low melting index and has poor compatibility with polyolefins, so that the crosslinking reaction occurs significantly in the graft reaction. It is said that this is due to the fact that the situation occurred in a strange manner.

In the method of grafting maleic anhydride onto polyolefin while it is still in a molten mixed state, it is difficult to uniformly blend maleic anhydride and radical initiator into polyolefin.
If the reaction is carried out in a non-uniform blended state, the modified polyolefin is likely to gel, and this method is extremely difficult to remove unreacted maleic anhydride and undecomposed radical initiator from the modified polyolefin after the modification reaction. Difficulties exist.

In particular, maleic anhydride that remains as an unreacted component is a highly toxic substance to the human body, so unless it is completely removed, it is not a practical method for producing adhesive polyolefin. do not have.

As a result of detailed research into the reaction of modifying polyolefin with maleic anhydride to produce an adhesive polyolefin, the present inventors discovered the following facts and arrived at the present invention. For structural analysis of altered products, alcoholic KOH
In addition to measuring the amount of maleic anhydride grafted by titration using a solution, we also used infrared absorption spectroscopy and nuclear magnetic resonance to observe the distribution state of maleic anhydride groups in polyolefin molecular chains. dupont ds
The melting point distribution was measured using a C-990 differential thermal analyzer. The relationship between the chain length of the methylene group (-CI(2-)) in the polyolefin main chain and the melting point of that chain is known as the Broadburst equation, as described by CM, G., Broadhureti J., Ohe.
m.

Phys+ 36.2578 (1962):]. Xylene, toluene! When the grafting reaction of maleic anhydride onto a polyolefin is carried out using a solvent that is easily attacked by initiator radicals, such as an alkyl aromatic compound such as cumene, or an aliphatic hydrocarbon such as hexane or heptane, the following F. There's a problem.

■ At most 10 grams of maleic anhydride subjected to the reaction,
By simply adding to the polyolefin, the remaining maleic anhydride forms an adduct in a 1:1 molar ratio with the solvent used in the reaction. Furthermore, this adduct has no graft reactivity and is not economical.

■ The molecular length of the side chain maleic anhydride group grafted onto the polyolefin is calculated to be 1. Moreover, it is added and dispersed uniformly on the polyolefin molecular chain at appropriate intervals.

(This is referred to as dispersed addition of maleic anhydride.) C) When maleic anhydride is dispersedly added, the adhesive strength of the modified product is extremely low if the maleic anhydride content is less than 0.5 x 10' mol per 12 modified polyolefins.

As a result of research into improving the problems of the conventionally known modified polyolefin production methods as described above, it was found that when a solvent that is not attacked by initiator radicals such as benzene, monochlorobenzene, and dichlorobenzene is used.

(1) The addition efficiency of the maleic anhydride subjected to the reaction to the polyolefin is sufficiently high at 50 to 100 cm, and it is economical.

9) The maleic anhydride group grafted onto the polyolefin is locally added to the polyolefin molecular chain, and the average molecular length of the side chain is calculated to be 6 (referred to as localized addition of maleic anhydride)■ When maleic anhydride is locally added to the polyolefin, the amount is 0.00% per 12 modified polyolefins.
It has strong adhesive strength even if the maleic anhydride content is less than 5 x 10 mol/f.
The modified polyolefin containing maleic anhydride groups of L has sufficient adhesive strength.

They discovered this and completed the present invention.

That is, in the present invention, in a method of grafting maleic acids onto a polyolefin using a radical initiator, benzene or a halogenated aromatic hydrocarbon is used as a solvent, and 0.0. 01 X 10-'~0.5 X 10-'
The present invention relates to a method for producing an adhesive polyolefin characterized by molar grafting.

According to the method of the present invention, the reaction rate of the maleic acids grafted onto the polyolefin is extremely high and economical, and there is no problem of removing unreacted maleic acids from the modified polyolefin, which is the biggest drawback of the bath melt kneading method. . That is,
When a poor solvent such as acetone is added to the grafting reaction solution to precipitate and recover the modified polyolefin, unreacted maleic acids and undecomposed radical initiators are dissolved in the liquid side, so they cannot be completely separated from the modified polyolefin. I can do it. Further, the adhesive polyolefin produced by the method of the present invention can be used as it is or mixed as appropriate with an unmodified polyolefin.

In the present invention, in addition to using a specific solvent in the present invention, maleic acid groups are modified with polyolefin 1.
It is necessary to graft from 0.01 X 10-' to 0.5 X 10' moles per 2. If the amount of maleic acid groups added is outside the above range, the adhesive strength of the modified polyolefin will decrease.

The raw material resin used in the present invention is polyethylene.

Polyolefins such as polypropylene, copolymers of ethylene and α-olefins such as propylene or 1-butene.

The maleic acids used in the modification reaction are maleic acid, fumaric acid, mesaconic acid, and 5-norbornene-citraconic acid.
213-dicarboxylic acid.

Examples include 1.2,3.6-titrahydrophthalic acid and its anhydrides and monoesters.

As a radical initiator.

Diisopropyl peroxide, di-tert-butyl peroxide, tert-butyl hydroperoxide, dicumyl peroxide, cumyl hydroperoxide, dilauroyl peroxide.

Examples include organic peroxides such as dibenzoyl peroxide and methyl ethyl ketone peroxide.

As a medium.

Benzene, halogenated aromatic hydrocarbons 9 such as monochlorobenzene, orthodichlorobenzene.

Examples include solvents that are stable against radical attack, such as monobromobenzene, and mixed solvents thereof may also be used.

To carry out the process of the invention, the bath medium 1. 10 to 300 parts by weight of polyolefin (preferably 50 to 200 parts by weight) per part by weight of O'OO, and 0.01 to 2.0 parts by weight of maleic acids (preferably 50 to 200 parts by weight) per 100 parts by weight of polyolefin.
(preferably 0.02 to 1.0 parts by weight).

The radical initiator is used in an amount of 0.2 to 2.0 parts by weight (preferably 0.4 to 0.8 parts by weight) per 100 parts by weight of the polyolefin.

The reaction temperature is usually 90-250°C, preferably 110-250°C.
The reaction is continued at 00°C for 1 time for at least 60 units (preferably 80 units or more) of the radical initiator to decompose. The reaction time varies depending on the type and amount of the radical initiator used and the reaction temperature, but is usually 1 to 10 hours.

Although the reaction may be carried out in air, it is preferably carried out in an inert gas atmosphere such as nitrogen to prevent oxidation of the polyolefin.

Example 1 A separable glass flask with an internal volume of 1 ton which was sufficiently purged with nitrogen was charged with a density of [+, 922. Melt Index6.
4 polyethylene 402. 40 ml of maleic anhydride and 240 mg of dicumyl peroxide as a radical initiator were charged, and 40 ml of orthodichlorobenzene was added as a solvent. Next, the separable flask was immersed in an oil bath and the temperature inside the reaction system was raised while stirring to dissolve the polyethylene. After raising the temperature to 125°C, this temperature was maintained for 5 hours to continue the reaction.

After the reaction is completed, cool the system and when the temperature in the system reaches around room temperature, add acetone 5001111 and stir thoroughly.
The modified polyethylene was washed with P separately and with 500 ml of acetone, and dried under reduced pressure at 40°C overnight to obtain modified polyethylene in the form of white powder. This modified polyethylene showed characteristic absorption of acid anhydride at 1860 cm' and 1780 cm' in the infrared absorption spectrum, proving that it was grafted with maleic anhydride.

Medium: When the content of maleic anhydride groups was determined by the tll rM constant, it was found to be 9 x 10-6 moles, which corresponds to 90 parts of the charged maleic anhydride, per 12 of the modified polyethylene. Furthermore, the modified polyethylene was soaked with acetone for 5 hours, extracted, and then subjected to the same analysis, but the results were exactly the same. This means that the modified polyethylene does not contain any unreacted maleic anhydride.

The modified polyethylene produced by the above method was heat-pressed at 150°C to form a sheet with a thickness of 1111111, and this notebook was sandwiched between two steel plates with a thickness of about 0.2°.
After melt bonding for 5 minutes at a C2 pressure of 202 cm, the bond strength was measured and showed a practically sufficient bond strength of +3.5 K97 cm.

Comparative Example 1 A glass separable flask with an internal volume of 1 ton which was sufficiently purged with nitrogen was charged with a density of o and 922. Polyethylene 402 with a melt index of 3.4. 400 ml of maleic anhydride and 240 ml of dicumyl peroxide as a radical initiator were charged, 400 ml of mixed xylene was added as a solvent, and the reaction was continued at 125° C. for 5 hours in the same manner as in Example 1. After the reaction was completed, the product was precipitated using acetone, washed twice, and dried under reduced pressure at 40°C overnight to obtain modified polyethylene in the form of white powder. Based on infrared absorption spectra and neutralization titration, this modified polyethylene has a concentration of 9.5X 1, which corresponds to 9.5% of the maleic anhydride charged per 12% of the modified polyethylene.
It was confirmed that 0-' mol of maleic anhydride was grafted. The adhesive strength of this modified polyethylene was measured in the same manner as in Example 1 and was found to be 0.4 Kv'cm L.

Example 2 A glass separable flask with an internal volume of 1 ton, which had been sufficiently purged with nitrogen, was charged with a density of 0.922. 40v polyethylene with melt index 3°4, maleic anhydride 20~. 620~ of tert-butyl perbenzoate was prepared as an initiator, and 400 mg of monochlorobenzene was added as a solvent.
The reaction was continued at 125°C for 5 hours in the same manner as in Example 1. After the reaction is complete.

Precipitate, wash, and collect using acetone, and store at -40°C at night.
The mixture was dried under reduced pressure to obtain modified polyethylene in the form of a white powder.

Infrared absorption spectra and neutralization titration revealed that 4% of the maleic anhydride charged per 12% of the modified polyethylene.
, 2×10′ mol of maleic anhydride groups were confirmed to be grafted. The adhesive strength of this modified polyethylene to a steel plate was 2 Kv/cm, which was a sufficiently strong value.

Comparative Example 2 The same procedure as in Example 2 was carried out except that 150 μm of maleic anhydride and mixed xylene were used as the solvent.
A modified polyethylene grafted with 7 x 10-' moles of maleic anhydride corresponding to 0.05 was obtained. The adhesive strength of this modified polyethylene to steel plate is 0.1K17cm
It didn't work.

Examples 3-7. Comparative Examples 3 to 5 Amount of maleic anhydride, type and amount of initiator, type of solvent 1
The same procedure as in Example 1 was carried out except that the reaction time or reaction temperature was changed as shown in Table 1.

The results are summarized in Table 1.

one Example 8 A glass autoclave was used as the reactor.

Modified polyethylene was obtained in the same manner as in Example 4 except that benzene was used as the solvent. The adhesive strength of this modified polyethylene to the steel plate was 5.2 to 9/crn.

Patent applicant: Ube Industries Co., Ltd. 33-

Claims (1)

[Claims] In the method of grafting maleic acids onto polyolefin using a radical initiator, benzene or halogenated aromatic hydrocarbon is used as a solvent, and 0.01×1 maleic acid groups are added per 1 g of modified polyolefin.
A method for producing an adhesive polyolefin, which comprises grafting 0' to 0.5X 10-' moles.