KR830000409B1 - Process for production of water-curable silane modified alkylene alkylacrylate copolymer - Google Patents

Abstract

Water-curable elastomers, useful as insulation for wire, are prepd. by trating alkene-alkyl acrylate copolymers with silane in the presence of org. titanate catalysts. Thus, 40 g ethylene-Et acrylate copolymer having melt index 2.4 was mixed with 2.5% AcO(CH2)2Si(OMe)3 and 1% tetraisopropyltitanate, heated 15 min at 155-160≰C, blended with 5% ethylene-vinyl acetate copolymer masterbatch contg. 1% Bu2Sn dilaurate, pressed into plaques, suspended 3 h in water at 90≰C, and dried to give silane-modified copolymer having tensile strength 1500 psi, elongation 240%, dielec. const. 2.672 (60 Hz).

Description

Process for preparing hydraulic silane modified alkylene alkyl acrylate copolymer

The present invention relates to a process for preparing a water-curable silane modified alkylene alkyl acrylate copolymer.

It is known to vulcanize polyolefins to extend the application temperature above the melting point of the resin. Continuous chemical and radiation vulcanization processes are well known in the field of wires and cables. Predominant commercial processes include free radical crosslinking reactions induced by peroxides. The process step of covering the wires and cables with a peroxide-curable coating involves continuously extruding the curable polyolefin composition onto the wires and cables and then contacting the high pressure steam (250 to 300 psi) to cause peroxide decomposition and rapid vulcanization of the polyolefin composition. It includes what was said. When coating a wire or cable with a radiation curable polyolefin coating composition, use the same process as for peroxide curing, except that an electron beam is used as the energy source for vulcanization. .

However, both peroxide and radiation curing methods have disadvantages including high unit capital ownership and high energy use. In addition, in the case of using a peroxide curing process, it is difficult to carry out coating because of the difficult adjustment of the process. If the process takes too long, the polyolefin can crosslink and solidify (scorching) in the process equipment. Thus, this requires a time delay to remove cross-linked product from the device and results in loss of material.

U.S. Patent No. 3,646,155 (February 29, 1972) discloses a free radical grafting reaction of polyolefin polymer backbones, i.e., polyethylene or unsaturated organosilanes of up to 50% propylene and / or butylenes with ethylene. Is described. The resulting thermoplastics have a normal extrusion fixation performance, which allows molding or processing as end use. After the graft reaction, it is vulcanized by contact with water. Elevated temperatures (80-100 ° C) and silanol condensation catalysts are used to promote vulcanization.

The reaction can be expressed as follows.

However, the peroxide initiator used in reaction (I) may be reactive to polyethylene and may precure the polyethylene. That is, the polyethylene can be scorched, which makes the process for end use difficult.

We have now developed an easy way to prepare novel hydraulic silane modified alkylenealkylacrylate copolymers by reacting alkylenealkylacrylate copolymers with silane in the presence of an organic titanate catalyst.

The present invention relates to a process for preparing a hydraulic silane modified alkylene alkyl acrylate copolymer without undesirable side reactions such as scoping.

Another object of the present invention is to provide a method for curing a silane-modified alkylene alkylacrylate copolymer.

We now know that hydraulic silane modified alkylenealkylacrylate copolymers can be prepared by reacting alkylenealkylacrylate copolymers with silane in the presence of an organotitanate catalyst. The alkylenealkylacrylate copolymers prepared can be cured with moisture / water and optionally with moisture / water in the presence of a silanol condensation catalyst. Moreover, the novel olefinic copolymers containing alkylene units, alkylacrylate units and pendant hydrolyzable silane groups are suitable for use in films, wire and cable insulators, sheaths and adhesives, for molding, and pipes for the transport and storage of water. It is particularly suitable for use in compression applications such as hot water pipes.

1. Alkylene alkylacrylate copolymer

)과 같은 저급알킬-치환된 아크릴산]의 알킬에스테르를 포함한다. 공중합체를 형성하는데 적합한 특정아크릴산 에스테르에는 아크릴산 또는 메타아크릴산의 메틸, 에틸, 프로필, 이소프로필, 부틸, 이소부틸, 3급-부틸, 헥실, 2-에틸-헥실, 메실, 라우릴 및 스테아릴에스테르 등이 포함된다. 알킬아크릴레이트의 알킬잔기는, 필요에 따라 본 발명의 범위와 요지로부터 이탈됨이 없이 실질적으로 공중합체의 형성을 방해하지 않고 그들의 바람직한 성질을 열화시키지 않는 특정한 간단한 치환기를 함유할 수 있다.The copolymer blue used in the present invention is composed of a unit corresponding to an alkylene group and an alkyl ester of acrylic acid. Alkyl acrylic acid esters for the purposes of the present invention means alkyl esters of acrylic acid [see: Monomer Chemistry is defined as an additive in Milton B.Hron's Acrylic Resins (p15f)), unsubstituted acrylic acid (CH ₂ = CH-COOH ) And simple alpha-substituted acrylic acids such as methacrylic acid (

Lower alkyl-substituted acrylic acid] such as Particular acrylic esters suitable for forming the copolymer include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, hexyl, 2-ethyl-hexyl, mesyl, lauryl and stearyl esters of acrylic or methacrylic acid. Etc. are included. The alkyl residues of the alkylacrylates may, if desired, contain certain simple substituents that do not depart from the scope and spirit of the present invention without substantially hindering the formation of the copolymers and degrading their desirable properties.

Preferred alkyl esters are simple lower alkyl esters of acrylic acid, for example methyl, ethyl and butyl acrylate and methacrylate.

The alkylene group of the alkylene alkylacrylate copolymer contains 2 to 18 carbon atoms, preferably 2 to 3 carbon atoms.

Preferred copolymers are ethyleneethylacrylate copolymers containing from about 1 to about 50 weight percent ethylacrylate and most preferred copolymers are ethyleneethylacrylate copolymers containing from 2 to about 20 weight percent ethylacrylate. .

Alkylenealkylacrylate copolymers generally have a density of about 0.92 to 0.94 (measured by the ASTM 1505 test method under the conditions of ASTM-148-72) and a melt index of about 0.5 to 500 deggrams / minute (44 psi pressure). Under the test method of ASTM D-1238).

2. Silane

The silanes used to form the hydraulic silane modified alkylenealkylacrylate copolymers have the general formula:

X-(-CH _2- ) _a -SIY ₃

In the above general formula

이고X is OH, SH, NH ₂ or

ego

또는 C₁-C₁₈알킬이고R is

Or C ₁ -C ₁₈ alkyl

R ₁ is independently hydrogen or C ₁ -C ₁₈ alkyl

a is an integer from 1 to 18

Y is independently hydrogen, a hydrocarbon group of 1 to 18 carbon atoms, C ₁ -C ₁₈ alkoxy, or-(C- (CH _2- ) _a -O-(-CH _2- ) _a -H, provided that at least of Y One is not hydrogen or a hydrocarbon group.

Preferred silanes have the following general formula:

X-(-CH _2- ) _a -Si (OR ₂ ) ₃

In the above formula

x and a are the same as above

R ₁ is C ₁ -C ₈ alkyl.

Most preferred silanes are the following compounds.

(3) organic titanate catalyst

The organic titanate catalyst of the present invention has the following general formula.

의 아실(여기에서 R₆는 탄소수 1 내지 20의 알킬임)이고R ₂ ′, R ₃ , R ₄ and R ₅ in the above formula are independently hydrogen, alkyl, cycloalkyl, aryl, acroaryl, aralkyl (where the groups other than hydrogen contain 1 to 20 carbon atoms), lactyl Or general formula

Is acyl, wherein R ₆ is alkyl having 1 to 20 carbon atoms

b is an integer from 1 to 100.

These organic titanates are readily available materials and are prepared by the methods described in US Pat. No. 2,984,641.

Preferred organic titanate catalysts have the following general formula.

Ti (OR ₇ ) ₄

Wherein R ₇ is C ₁ to C ₂₀ alkyl, preferably C ₁ to C ₈ alkyl.

Most preferred organic titanates are tetrabutyl titanate and tetraisopropyl titanate.

Organic titanate catalysts also include chelates. This chelate is described in US Pat. No. 2,984,641 and is readily available. Chelates include tetraoctyleneglycol titanium, triethanolamine titanate, titanium acetylacetonate and titanium lactate.

These titanates can also be used with sub-catalysts known as sub-CO-catalysts in the esterification reaction. These sub-catalysts include transition metal carboxylate salts.

These organic titanates are used in catalytic amounts and the preferred amount of organic titanate is about 0.10 to about 2.0 weight percent based on the weight of the resin.

4. Method for producing silane modified alkylene alkyl acrylate copolymer

The reaction of the alkylene alkylacrylate copolymer with the organosilane compound may be carried out at a temperature from about 25 ° C. up to the volatilization temperature of the silane. This temperature is preferably about 140 ° to 225 ° C, most preferably about 155 ° to 225 ° C. However, higher temperatures than the silane's volatilization temperature can be used with increasing pressure.

The reaction is carried out at atmospheric pressure, but more pressure can be used.

This reaction is carried out using any suitable device, but is preferably carried out under mechanical operating conditions of the copolymer, for example using a brabender or a Benbury mixer.

The copolymer and the silane reactant are mixed in a conventional manner. For example, organosilane is added to the solvent copolymer followed by the addition of an organic titanate catalyst, or alternatively a copolymer containing an organic titanate catalyst is reacted with silane, or the organic titanate and silane first After mixing, it is added to the solvent copolymer.

The reaction is preferably carried out in the absence of a solvent, but if necessary, an organic solvent may also be used, for example, to add an organic silane to the reaction.

The reaction of the copolymer and silane is as follows.

(Using ethylene ethyl acrylate copolymer):

In the crosslinking reaction of the silane-modified alkylene alkylacrylate copolymer, it is effective to expose the copolymer to moisture. Moisture present in the atmosphere is sufficient to cause crosslinking. However, the rate of crosslinking can be facilitated by using an artificially humidified atmosphere, immersing in water, or optionally using a high temperature. Crosslinking is effective to be carried out at about 25 ° to 100 ° C, preferably at 70 ° C to 100 ° C. In addition, the silane-modified alkylene alkyl acrylate copolymer may be exposed to steam at a temperature of 100 ° C or higher.

Moreover, crosslinking can be carried out in the presence of a silanol condensation catalyst. A unique advantage of the present invention is that the crosslinking reaction proceeds at a sufficient rate even in the absence of silanol condensation catalyst. Organic titanate catalysts and catalyst residues used in the transesterification reaction also promote crosslinking reactions. The reaction of organosilanes with polyolefins using peroxide or radiation in the prior art was added with a catalyst in the separation step to obtain a satisfactory crosslinking rate.

Alternatively, a wide range of materials well known in the art, which act as silanol condensation catalysts, are used in the process of the present invention. Such materials include metal carboxylates (e.g. dibutyltin dilaurate, stanus acetate, stanus octoate, lead naphthenate, zinc octoate, iron-2-ethylhexate and cobalt naphnate), organic bases (E.g. ethylamine, hexylamine, dibutylamine and piperidine) and acids (e.g. inorganic acids and fatty acids).

5. Silane Modified Alkylene Alkylacrylate Copolymers

The silane-modified alkylene alkylacrylate copolymer prepared according to the method of the present invention is at least 50% by weight of the polymerized alpha olefin unit of the following general formula (I), and at least 0.1% by weight of the polymerization unit containing a radical of the following general formula (II). And a polymerization unit of the following general formula (III).

In the above formula

A is hydrogen or an alkyl radical having 1 to 16 carbon atoms

C ₁ is the carbon atom of the basic polymer chain

또는 -S 라디칼이고B is -O-,

Or -S radical

Q is a divalent radical having 1 to 18 carbon atoms bonded to B and D via a carbon atom

의 라디칼(여기서 V는 수소 또는 탄소수 1 내지 18의 탄화수소라디칼임)과 가수분해 가능한 기를 함유한 실리콘이고D is a general formula

Is a silicone containing a radical of (where V is hydrogen or a hydrocarbon radical having 1 to 18 carbon atoms) and a hydrolyzable group

Z is a hydrolyzable group

W is an alkoxy radical having 1 to 18 carbon atoms.

6. Supplements

Adjuvants are fillers containing carbon black, clay, talc, magnesium silicate, calcium carbonate, silica, aluminum hydroxide, calcium silicate, etc., which can be used with a silane-modified alkylene alkylacrylate copolymer in sufficient amount to obtain a predetermined effect. have.

7. Examples

The following examples merely illustrate the invention and do not limit the scope of the invention.

Example 1-10

The brabender mixer is heated to 160 ° C. and filled with an ethyleneethylacrylate copolymer having a malt index of 4.5 and an ethylacrylate content of 18% under an argon atmosphere. Solvent the resin and add the amount of silane as described in Table 1 and mix until the contents are uniform. Tetraisopropyl titanate catalyst (1.0% by weight) is added slowly and the contents are heated at 155-160 ° C. for about 15 minutes.

After preparation, the copolymer is mixed with 5% by weight of 1% by weight dibutyltin dilaurate resin masterbatch, compressed into plaque and suspended in water at 90 ° C. for 3 hours.

Master batches are prepared as follows: Ethylene vinyl acetate copolymer (containing 10% by weight of vinyl acetate, melt index 2.0) is treated with an appropriate amount of 25% by weight solution of dibutyltin dilaurate contained in isopropyl alcohol. A 1 wt% dibutyltin dilaurate resin master batch is prepared. The solvent is removed by heating at 40 ° C. in a vacuum oven for 12 hours. The material thus produced is stored under argon until used.

The plaque is dried by rinsing in water, dried and removed from the vacuum oven at 50 ° C. for 1 hour.

Subsequently, the degree of cure is measured using a plaque according to the Monsanto Rheometer cure test method. This test procedure is described in detail in US Pat. No. 4,018,852 (April 19, 1977). Figure 1 of this patent shows a typical Monsantoleometer curve. Hardness (highest crosslink density) is denoted by H. This is measured in inches-pounds of torque on the rheometer test apparatus. The higher the value of H, the higher the crosslink density.

Plaques are also used to measure decalin extractables according to the Referee Method A of ASTM D-2765. The decalin solubgle portion of the polyethylene compound is a quantitative measure of the degree of cure. The larger this weight% value, the lower the degree of curing. The test results are shown in Table 1.

TABLE 1

(1) Adjust the weight to molar equivalent

(2) 15 minutes to 190 ℃

Example 11-16

The procedure of Example 1-10 was repeated except that 40 g of ethyleneethyl acrylate copolymer having a melt index of 2.4 and an ethyl acrylate content of 14% was used. Tetraisopropyl titanate catalyst and methacryloxypropyltrimethoxysilane (amount shown in Table II) are also added.

After preparation, the silane-modified ethyleneethylacrylate copolymer is compressed into plaques and cured according to the procedure of Example 1-10 above. The plaque is measured to cure following the procedure of Examples 1-10. The results are shown in Table II.

The data in Table II shows the effect of silane concentration on the degree of cure. As the amount of silane introduced into the system increases, the degree of crosslinking increases.

TABLE II

Effect of Silane Content on Hardness

[Example 17-23]

Repeat the procedure of Example 11-16 exactly, adding 2.5% by weight of methacryloxypropyl tramethoxysilane and tetraisopropyl titanate catalyst in the amounts shown in Table III. The prepared copolymer is compressed into plaques and cured according to the procedure described in Examples 11-16.

Decalin extraction rate and degree of cure were measured according to the procedure of Examples 1-10. The results are shown in Table III.

The data in Table III shows the effect of catalyst concentration on the reaction. The higher the titanate catalyst concentration, the lower the curing value.

TABLE III

Effect of Catalyst Concentration on Curing Degree

Example 24-28

Repeat the procedure of Example 11-16 exactly except using 40 g of copolymer containing% ethyl acrylate as indicated in Table IV. In addition, 1.0% by weight of tetraisopropyl titanate catalyst and 2.5% by weight of methacryloxypropyltrimethoxy silane are used for the reaction. The prepared copolymer is compressed into plaques and cured according to the procedure of Examples 1-10.

Hardness and decalin extraction rate were measured according to the procedure of Example 1-10.

The copolymer type, ethyl acrylate content%, decalin extraction rate and degree of cure are described in Table IV.

From the data in Table IV, it can be seen that various copolymers are suitable as base resins in the process of the present invention.

Table IV

(1) The content of butyl acrylate is indicated.

Example 29

Repeat the process of Example 11-16 except using 1.0 wt% of tetraisopropyl titanate catalyst and 2.5 wt% of methacryloxypropyltrimethoxy silane. The reaction is heated at 155 ° -160 ° C. for 10 minutes. The reaction is completed in about 10 minutes. Even if the heating time at this temperature is extended, if the moisture is removed from the reaction, the degree of grafting reaction of the silane to the copolymer is not lowered and no scorching occurs.

Example 30-36

Repeat the procedure of Examples 11-16 except using 1.0% tetraisopropyl titanate and 2.5% methacryloxypropyl trimethoxy silane.

The prepared silane modified ethylene ethyl acrylate copolymer was compressed into plaque and cured for the time shown in Table V according to the procedure of Examples 1-10.

Hardness and decalin extraction rate were measured according to the procedure of Example 1-10. The results are shown in Table V.

From the data in Table 5, it can be seen that the sample is fully cured within 1 hour and does not need to be heated longer.

TABLE V

Example 37-44

Repeat the process of Example 11-16 except using an ethyleneethylacrylate copolymer having a melt index of 4.5 and an ethyl acrylate content of 18%. In addition, 2.5% by weight of silane and 1% by weight of tetraisopropyl titanate shown in Table IV are used.

After preparation, the copolymer (Examples 37-40) is compressed into plaques and cured for 1 and 3 hours, respectively, using a master batch catalyst as described in Examples 1-10. The degree of cure is measured following the procedure in Examples 1-10 using plaques.

After preparation, the copolymers (Examples 41-44) are compressed into plaques without addition of the master batch catalyst and heated at 90 ° C. for 3 hours. Curing degree is measured according to the procedure of Example 1-10.

From the data in Table VI, it can be seen that a high degree of crosslinking is obtained in the absence of a silanol condensation catalyst.

Table VI

Example 45-46

Repeat the process of Example 11-16 except using 40 g of ethylene ethyl acrylate copolymer having a melt index of 4.5 and an ethyl acrylate content of 18%. In addition, silanes of the kind and amount shown in Table VII are added and tetraisopropyl titanate (1.0% by weight) is used as a catalyst.

After preparation, the silane modified ethylene ethyl acrylate copolymer is compressed into plaques and cured for 1 and 3 hours, respectively, following the procedure of Examples 1-10. Hardness and decalin extraction rate were measured according to the procedure of Example 1-10.

From the data in Table V, it can be seen that the triethoxy containing silane exhibits a lower degree of cure than the trimethoxy containing silane under the same conditions.

[Table VII]

Effect of Silane Alkoxy Group on Cure Rate

Example 47-49

Repeat the process of Example 11-16 except using 40 g of ethylene ethyl acrylate copolymer having a melt index and ethyl acrylate content% described in Table VII. Also 2.5% by weight of CH ₃ COO (CH ₂ ) ₂ Si (OCH ₃ ) ₃ silane and 1% by weight of tetraisopropyl titanate are used.

After preparation, the silane modified ethyl acrylate copolymer is compressed into plaques and cured according to the procedure of Examples 1-10. Hardness and decalin extraction rate were measured according to the procedure of Example 1-10. In addition, the following tests are conducted on the cured silane-modified ethylene ethylacrylate copolymer:

Saddle Strength and Shinto: D-638-72

* Tensile strength and elongation after heat aging at 121 ° C. for one week in an oven.

* Secant modulus ASTM-D 882-758

* Dielectric constant and dissipation factor (60 cycles) ASTM-D 150-74

* Denaturation at 121 ° and 175 ° C: ASTM 621

The results are shown in the table below. The silane modified copolymer is also extruded with American Wire Gauge Copper No. 14 to coat 30 mils thick and immersed in water to cure the coating. Tensile strength and elongation (ASTM 412-68) and the tensile strength and elongation after heat aging for 1 week in 121 ℃ oven is measured. The results are described in Table VII.

[Table VII]

(1) 75 wt% ethylene ethylacrylate copolymer, 24.5 wt% talc and 0.5 wt% aggrite MA heat stabilizer

(2) measuring on wire

(3) Values measured on the base resin as a control

Claims (1)

The water-curable silane-modified alkylene alkylacrylate air is characterized in that the alkylene alkylacrylate copolymer is reacted at a volatilization temperature of about 25 ° C. to silane in the presence of the catalytic amount of silane and organic titanate catalyst of the following general formula. Method of preparing coalesce. X-(-CH _2- ) _a -SiY ₃ In the general formula, X is OH, SH, NH ₂ or

And R is

Or C ₁ -C ₁₈ alkyl, R ₁ is independently hydrogen or C ₁ -C ₁₈ alkyl, a is an integer from 1 to 18 and Y is independently hydrogen, a hydrocarbon group of 1 to 18 carbon atoms or C ₁ -C ₁₈ alkoxy Provided that at least one of Y is not hydrogen.