JP5229973B2 - Resole-type alkylphenol-formaldehyde co-condensation resin crosslinking agent - Google Patents

Description

The present invention relates to a rubber resin cross-linking agent comprising a phenol / formaldehyde co-condensation resin, and more particularly to a resin cross-linking agent comprising a resol-type alkylphenol / formaldehyde co-condensation resin containing a plasticizer.

Conventionally, flaky or particulate resol-type alkylphenol-formaldehyde cocondensation resins have been used as the resin crosslinking agent, but it is known that the dispersibility in rubber is poor. In order to sufficiently disperse the resin cross-linking agent in the rubber, it is preferable to knead at a temperature equal to or higher than the softening point of the resin. However, when the kneading temperature is 120 ° C. or higher, the rubber cross-linking reaction starts and a uniform rubber composition is obtained. Cannot be obtained. For this reason, a resin crosslinking agent having a softening point of 115 ° C. or lower is generally used.

It is known that the resin cross-linking agent is used in the form of fine powder or the softening point of the resin cross-linking agent is lowered, so that dispersibility is improved. Will not be able to withstand actual use.
As a method of measuring the resin cross-linking agent, preventing dust in the kneading operation step with rubber, and improving the dispersibility of the resin cross-linking agent in rubber, a method of creating a master batch of the resin cross-linking agent and rubber is disclosed. Yes. (Patent Document 1)

  On the other hand, prevention of environmental pollution has become a social issue in recent years, and reduction of impurities, residual raw materials and residual solvents in products has been demanded. In the production of a resin cross-linking agent, it is difficult to separate and reduce the residual amount of alkylphenol as a raw material, and it is preferable from the viewpoint of production cost to reduce the residual amount by a method that completes the condensation reaction as much as possible. However, this method inevitably increases the softening point of the obtained resin cross-linking agent, and the method described in Patent Document 1 has a drawback in that the dispersibility in the rubber described above is lowered.

JP-A-7-173202

The object of the present invention is that the softening point is lower than the crosslinking reaction temperature of rubber, the dispersibility in rubber, the crosslinking performance of rubber and the blocking resistance during storage of the resin crosslinking agent have the same performance as conventional products, and It is to provide a resin cross-linking agent that is greatly reduced in terms of residual solvent and residual unreacted alkylphenol.

As a result of intensive studies aimed at solving the problems, the present inventors have found that the object of the present invention can be achieved by adding a plasticizer to a resol type alkylphenol-formaldehyde cocondensation resin.

The present invention will be described in detail below.
The resin crosslinking agent of the present invention can be applied to all rubbers capable of sulfur crosslinking, and specific rubbers include natural rubber, SBR, isoprene rubber, NBR, butyl rubber, EPDM, CR and the like.

  The resol-type alkylphenol / formaldehyde cocondensation resin used in the present invention can be synthesized by a known method described in Plastic Material Course 15 “Phenolic Resin” (published by Nikkan Kogyo Shimbun), etc. Those of 1 to 20 are preferably used. As the molecular weight of the cocondensation resin, those having a polystyrene equivalent weight average molecular weight of 2000 to 5000 are usually used. Further, from the viewpoint of preventing environmental pollution, it is preferable that the residual amount of alkylphenol as a raw material and the residual amount of the solvent used for the reaction are smaller in the resol type alkylphenol / formaldehyde cocondensation resin, specifically, less than 1% by weight respectively. Used to select one.

  Specific compounds of the resol type alkylphenol / formaldehyde cocondensation resin used in the present invention include cresol / formaldehyde cocondensation resin, ethylphenol / formaldehyde cocondensation resin, butylphenol / formaldehyde cocondensation resin, octylphenol / formaldehyde cocondensation resin, butylphenol. -Examples include octylphenol / formaldehyde co-condensation resin.

  The content of the plasticizer in the resol type alkylphenol / formaldehyde cocondensation resin of the present invention is 1 to 30% by weight, and 2 to 20% by weight is a preferable range. If the content of the plasticizer is less than 1% by weight, the effect of reducing the softening point is not observed, and if it exceeds 30% by weight, the hardness of the crosslinked rubber is decreased and the compression set is increased, which is not preferable.

（Ｒ_１は置換基を有していてもよい炭素数４〜１０の脂肪族基、Ｒ₃は炭素数４〜１３のアルキル基であり、かつ４≦（Ｒ₃の炭素数）≦１３である。ｍは１〜３の整数を表し、ｍが２〜３の場合、Ｒ₃の組み合わせは、同一であっても異なっていてもよい。）
で表される化合物からなる群から選ばれる少なくとも１種が含まれ、式（1）で表わされる化合物としては、例えば、２−エチルヘキシルオレート、ブトキシエチルオレート等の脂肪族モノカルボン酸エステルおよびその誘導体、ジイソブチルアジペート、ジブチルアジペート、ジ（２−エチルヘキシル）アジペート、ジイソデシルアジペート、ジイソトリデシルアジペート、ジメチルアゼレート、ジイソブチルアゼレート、ジブチルアゼレート、ジ（２−エチルヘキシル）アゼレート、ジイソデシルアゼレート、ジイソトリデシルアゼレート、ジメチルセバケート、ジイソブチルセバケート、ジブチルセバケート、ジ（２−エチルヘキシル）セバケート、ジイソデシルセバケート、ジイソトリデシルセバケート、ジブトキシエトキシエチルアジペート等の脂肪族ジカルボン酸エステルおよびその誘導体、アセチルトリブチルシトレート等の脂肪族トリカルボン酸エステルおよびその誘導体が挙げられる。式（１）で表わされる化合物の中でも、ジ（２−エチルヘキシル）セバケート、ジブトキシエトキシエチルアジペートがより好ましく、ジ（２−エチルヘキシル）セバケートが更に好ましい。

Specifically as a plasticizer in the present invention include aliphatic carboxylic acids derived material. Examples of the aliphatic carboxylic acid derivative, an aliphatic monocarboxylic acid esters, aliphatic dicarboxylic acid esters, aliphatic tricarboxylic acid esters and Examples thereof include derivatives thereof .
These types Symbol plasticizer, formula (1)

(R ₁ is an optionally substituted aliphatic group having 4 to 10 carbon atoms, R ₃ is an alkyl group having 4 to 13 carbon atoms, and 4 ≦ (carbon number of R ₃ ) ≦ 13) there .m is an integer from 1 to 3, when m is 2 or 3, the combination of R ₃ may be be the same or different.)
In contains at least one species selected from the group consisting of compounds represented by, as the compound represented by the formula (1), for example, 2-ethylhexyl oleate, butoxyethyl aliphatic monocarboxylic acid esters and derivatives oleate, etc. , Diisobutyl adipate, dibutyl adipate, di (2-ethylhexyl) adipate, diisodecyl adipate, diisotridecyl adipate, dimethyl azelate, diisobutyl azelate, dibutyl azelate, di (2-ethylhexyl) azelate, diisodecyl azelate, diisotridecyl Azelate, dimethyl sebacate, diisobutyl sebacate, dibutyl sebacate, di (2-ethylhexyl) sebacate, diisodecyl sebacate, diisotridecyl sebacate, dibutoxyethoxyethyl acetate Examples thereof include aliphatic dicarboxylic acid esters such as dipate and derivatives thereof, and aliphatic tricarboxylic acid esters such as acetyl tributyl citrate and derivatives thereof . Among the compounds represented by the formula (1) , di (2-ethylhexyl) sebacate and dibutoxyethoxyethyl adipate are more preferable, and di (2-ethylhexyl) sebacate is still more preferable.

The simplest method for mixing the resole-type alkylphenol / formaldehyde cocondensation resin and the plasticizer is to dissolve the plasticizer uniformly in the organic solvent solution of the resole-type alkylphenol / formaldehyde cocondensation resin and then distill the organic solvent away. Although it is a method, the method of mixing with a plasticizer at the temperature more than the softening point of resin is also possible.
The softening point of the resin cross-linking agent of the present invention is determined by the molecular weight of the condensation resin, the amount of residual alkylphenol, the amount of residual solvent, the amount of plasticizer added, and the softening point of the resin cross-linking agent is 85 to 115 ° C. The thing of -110 degreeC is preferable. If the softening point is lower than 85 ° C., mutual adhesion between the resins tends to occur during storage. Therefore, it becomes necessary to store the resin cross-linking agent of the present invention at a low temperature. The kneading temperature becomes high and the rubber cross-linking reaction is partially initiated, resulting in a deterioration in the quality of the compound.

Although there is no restriction | limiting in particular in the usage-amount of the resin crosslinking agent of this invention, 1-50 weight part with respect to 100 weight part of rubber | gum, Preferably 3-30 weight part is used.
The resin cross-linking agent of the present invention can be used in combination with a cross-linking accelerator such as CR, tin chloride, benzenesulfonic acid, calcium oxide, molecular sieve.

As the crosslinking temperature when the resin crosslinking agent of the present invention is used, the same temperature region as that of the conventional resin crosslinking agent can be applied. Specifically, an appropriate temperature according to the type of rubber is selected at 120 to 230 ° C.
The resin cross-linking agent of the present invention is suitably used for rubber products and TPE products used in medicine plugs, bladders, condenser packings, tire tubes, inner liners, hoses, tubes, gaskets, automobile interior materials, home appliance parts, etc. The

According to the present invention, the softening point is lower than the crosslinking reaction temperature of rubber, the dispersibility to rubber, the crosslinking performance of rubber and the blocking resistance during storage of the resin crosslinking agent have the same performance as the conventional product, and A resin cross-linking agent having a greatly reduced residual solvent and residual unreacted alkylphenol is obtained.

The details of the present invention will be specifically described with reference to Examples and Comparative Examples. The present invention is not limited by these examples.

The resin crosslinking agent was evaluated by the following method.
"Measurement of residual solvent and residual alkylphenol"
0.1 g of anisole as an internal standard substance was added to 1 g of a resin crosslinking agent, dissolved in 20 ml of acetone, and measured by gas chromatography.
"Measurement of softening point"
JIS K2207 compliant "Measurement of blocking resistance"
A flake-shaped resin cross-linking agent is put into a cylinder with a diameter of 4 cm so as to have a thickness of 3 cm, a plastic plate with a thickness of 1 mm and a diameter of 4 cm and a load of 360 g are placed on the top, and left in an oven at 45 ° C. for one week. Later, the blocking state of flakes was observed. Those having a blocking portion of 5% or more were evaluated as x.
"Measurement of dispersibility"
Using a Toyo Seiki Lab Plast Mill roller mixer (chamber capacity 60 cc), 50 g of a rubber compound having the following composition was prepared by kneading at a set temperature of 90 ° C. for 15 minutes. The obtained compound was formed into a sheet having a thickness of 0.5 mm with a roll, and the presence or absence of aggregates was visually observed. The thing without an aggregate was made into dispersibility (circle), and the thing with an aggregate was made into dispersibility x.
<Formulation> Polycerbutyl 402 100 parts by weight HAF carbon 50 parts by weight Stearic acid 1 part by weight Zinc white 5 parts by weight Resin crosslinking agent 40 parts by weight "Measurement of crosslinking characteristics with an oscillating rheometer"
Uses a rotary rheometer manufactured by Toyo Seiki Seisakusho.
Measured at a measurement temperature of 180 ° C and an amplitude angle of 3 °.

According to a known method, p-octylphenol, which is one of formaldehyde and alkylphenol, is used as a raw material, and a resole type resin having a residual amount of p-octylphenol of less than 1.0% is synthesized using an alkali catalyst. 12 parts by weight of di (2-ethylhexyl) sebacate as a plasticizer was added to 100 parts by weight of the resin in the toluene solution. Thereafter, toluene was distilled off under reduced pressure to obtain a resin crosslinking agent A.
The obtained resin cross-linking agent A was measured for residual solvent amount, residual p-octylphenol amount, softening point, blocking resistance and dispersibility, and listed in Table 1.
Using a roll of compounded compound of Policer butyl 402 (100 parts by weight), SRF carbon (50 parts by weight), stearic acid (1 part by weight), zinc white (5 parts by weight), and resin cross-linking agent A (12 parts by weight) And prepared by a conventional kneading method. The resulting compound was measured for cross-linking properties with an oscillating rheometer at 180 ° C. for 60 minutes and listed in Table 2.

  Resin crosslinking agent B was synthesized in the same manner as in Example 1 except that the amount of di (2-ethylhexyl) sebacate was changed to 8 parts by weight. Tables 1 and 2 show the results of measuring the amount of residual solvent, the amount of residual p-octylphenol, the softening point, the blocking resistance, the dispersibility, and the crosslinking characteristics with an oscillating rheometer in the same manner as in Example 1. Indicated.

  Resin crosslinking agent C was synthesized in the same manner as in Example 1 except that the amount of di (2-ethylhexyl) sebacate was changed to 4 parts by weight. Tables 1 and 2 show the results of measuring the amount of residual solvent, the amount of residual p-octylphenol, the softening point, the blocking resistance, the dispersibility, and the crosslinking characteristics with an oscillating rheometer in the same manner as in Example 1. Indicated.

(Comparative Example 1)
Resin crosslinking agent D was synthesized in the same manner as in Example 1 except that di (2-ethylhexyl) sebacate was not blended. Tables 1 and 2 show the results of measuring the amount of residual solvent, the amount of residual p-octylphenol, the softening point, the blocking resistance, the dispersibility, and the crosslinking characteristics with an oscillating rheometer in the same manner as in Example 1. Indicated.

(Comparative Example 2)
Resin crosslinking agent E was synthesized in the same manner as in Example 1 except that the amount of di (2-ethylhexyl) sebacate was changed to 20 parts by weight. Table 1 shows the results of measurement of the residual solvent amount, residual p-octylphenol amount, softening point, blocking resistance, and dispersibility of the obtained resin E.
With respect to the resin crosslinking agent E, the evaluation result of the blocking resistance was x, so the crosslinking characteristics with an oscillating rheometer were not measured.

Ｔ（１０）：加硫曲線から求められた、トルクの最大値と最小値との差の１０％に達するまでの時間（分）
Ｔ（９０）：加硫曲線から求められた、トルクの最大値と最小値との差の９０％に達するまでの時間（分）
ＭＬ ：加硫曲線から求められた、トルクの最小値（ｋｇ・ｃｍ）
ＭＨ ：加硫曲線から求められた、トルクの最大値（ｋｇ・ｃｍ）

T (10): Time (minutes) required to reach 10% of the difference between the maximum and minimum torque values determined from the vulcanization curve
T (90): Time (minutes) required to reach 90% of the difference between the maximum and minimum torque values determined from the vulcanization curve
ML: Minimum torque value (kg · cm) obtained from the vulcanization curve
MH: Maximum value of torque (kg · cm) obtained from vulcanization curve

Claims (3)

Resol-type alkylphenol-formaldehyde co-condensation resin has the formula (1)

(R ₁ is an aliphatic group having 4 to 10 carbon atoms, R ₃ is an alkyl group having 4 to 13 carbon atoms. M represents an integer of 1 to 3, and when m is 2 to _3, a combination of R ₃ May be the same or different.)
A resin composition containing 1 to 30% by weight of a plasticizer represented by the above, wherein the softening point of the resin composition is 85 to 115 ° C. Resin crosslinking agent according to claim 1, wherein the plasticizer and wherein the di (2-ethylhexyl) Sebake bets. The resin crosslinking agent according to any one of claims 1 to 2, wherein the content of unreacted alkylphenol in the resol type alkylphenol / formaldehyde cocondensation resin is less than 1.0%.