PLASTICIZING COMPOSITION

Description

The invention relates to a plasticizing composition comprising a resin of vinyl chloride type and a plasticizing agent which comprises at least one diester derived from a diacid chosen from succinic acid, glutaric acid, adipic acid, ethylsuccinic acid, methylglutaric acid and their mixture. The present invention relates more particularly to a plasticizing agent which comprises at least one diester derived from a diacid chosen from succinic acid, glutaric acid, adipic acid, ethylsuccinic acid, methylglutaric acid and their mixture and to its process of preparation. The present invention also relates to the uses of the plasticizing composition.

PRIOR ART

The plasticizing agents predominantly used are commonly known as “General Purpose” (GP) phthalates and thus represent 88% of consumption worldwide (6.7 MTon in 2011). The GP phthalates family includes DEHP (di(2-ethylhexyl) phthalate), DINP (diisononyl phthalate) and DIDP (diisodecyl phthalate). These three combined phthalates represent of the order of 83% of worldwide demand for plasticizers. DEHP alone represents approximately 50% of worldwide demand.

AIM OF THE INVENTION

The general aim of the invention is to provide novel plasticizing compositions. The plasticizing agent according to the invention exhibits a good performance for formulations of different types (foam, film and paste). This plasticizer rapidly gels, has a very low viscosity and ages very well. Efficient debubbling is one of these leading characteristics. The foams prepared with this plasticizer have low densities, a high rate of expansion and excellent qualities.

It is an aim in particular of the invention to provide a process which makes it possible to obtain the plasticizing agent.

The inventors have developed a process for the preparation of diester compounds starting from dinitriles and/or diacids employing a hydrolysis reaction followed by an esterification stage. A decoloration and/or purification stage makes it possible to obtain a pure diester.

The invention relates more particularly still to a process for the preparation of branched diester compounds, such as the diester of 2-methylglutaric acid (also known as MGA) and the diester of 2-ethylsuccinic acid (also known as ESA). The diester based on MGA alone or as a mixture with the diester based on ESA has a promising future in the milieu of the chemical industries. It is a plasticizer having plasticizing properties which can replace plasticizers based on phthalates and devoid of phthalates. It can be used as replacement for plasticizer, all alone or as a mixture with other plasticizers, for preparations/formulations of polyamides, of concrete, of polyesters, of polyurethanes, of vinyl chloride resins, of ethylene/vinyl acetate copolymers, of rubber, of mastics or of their mixtures.

The diester is obtained either from dinitriles, involving a diacid intermediate, or from diacid directly.

WO 2007/141404 provides for the preparation of diacid compounds by hydrolysis of dinitrile compounds in the presence of an excess of basic hydroxyl compounds, the carboxylate salt obtained subsequently being reacted with an inorganic acid in order to recover the diacid compound.

WO 2008/062058 provides for the preparation of diacid compounds by hydrolysis of dinitrile compounds in the presence of an excess of strong inorganic acid. WO2007/101929 provides for the preparation of diester by hydrolysis of dinitriles by the acid route or by the basic route; the diacid intermediate is subsequently esterified in the presence of methanol in order to obtain the corresponding dimethyl ester.

The present invention relates to a plasticizing composition comprising a resin and a plasticizing agent which comprises at least one diester of general formula (I):

RO—OC-A-CO—OR

derived from a diacid chosen from succinic acid, glutaric acid, adipic acid, ethylsuccinic acid, methylglutaric acid and their mixture,
in which:

• • A can be a linear or branched aliphatic chain comprising from 4 to 6 carbons, and
  • R can be an alkyl, a cycloalkyl or an aryl;
  • in particular, R is a substituted or unsubstituted cycloalkyl of 5 to 6 carbon atoms;
  • or a branched alkyl having from 4 to 10 carbon atoms.

Preferably, R is cyclohexyl or 2-ethylhexyl.

According to one embodiment of the invention, the plasticizing agent comprises a mixture comprising:

from 70% to 95% by weight of methylglutaric acid diester;
from 5% to 30% by weight of ethylsuccinic acid diester;
from 0% to 10% by weight of adipic acid diester.

According to another embodiment of the invention, the plasticizing agent comprises a mixture comprising:

from 95% to 100% by weight of methylglutaric acid diester, and
from 0% to 5% by weight of ethylsuccinic acid diester.

According to a preferred embodiment of the invention, the diester is the dicyclohexyl one of methylglutaric acid (DCH-MGA).

According to another embodiment of the invention, the diester is the diethylhexyl one of adipic acid (DCH-AA).

According to a third embodiment of the invention, the diester is the diethylhexyl one of methylglutaric acid (DEH-MGA).

The plasticizer of this invention can be prepared by esterification of diacids with these cyclic alcohols.

Reactions:

During the hydrolysis reaction of the dinitrile compound in the presence of acid, diacids and ammonium hydrogensulfate salt are formed. The latter can be recovered in value in the form of ammonium sulfates by its reaction with another molecule of ammonia.

Diagrammatically, the hydrolysis reaction of a dinitrile compound, for example 2-methylglutaronitrile, to give a diacid intermediate compound of the process of the invention can be represented in the following way:

In the reaction medium, the diacid compound is subsequently subjected to an esterification reaction with an alcohol, for example cyclohexanol, to give a diester of the process of the invention in the following way:

EXAMPLES

The percentages are given by weight, with respect to the weight of the total composition. The temperatures are given in degrees Celsius (° C.).

Example 1

General Procedure for the Synthesis of Plasticizers by Esterification

The catalyst, for example sulfuric acid, is added at 80° C. to a 1000 ml jacketed reactor equipped with a system for bleeding at the bottom, with a stirring system, with a nitrogen inlet, with a thermometer, with a Dean and Stark apparatus, with a pump for providing the vacuum and with a dropping funnel equipped with a cooling and heating system, via which the acid and the alcohol, the stoichiometry of which is 1:2, are added. The reaction takes place at 140° C. with removal of the water as the reaction progresses. The stripping with nitrogen thus promotes its removal and its recovery in the Dean and Stark apparatus. Once the amount of water co-produced has been completely collected, the temperature is raised above 140° C. and the pressure is lowered in order to remove the excess alcohol. The reaction medium is subsequently washed several times with sodium chloride solutions and, at the end, with demineralized water. The remaining catalyst is neutralized with sodium carbonate. A stage of decoloration by passing through charcoal can be carried out according to the level of coloration of the medium. The organic phase comprising the diester is subsequently purified and decolored by distillation. The pure and colorless diester is thus obtained with good yields.

RO—OC-A-CO—OR

TABLE 1
summary of the diesters prepared by
reaction of alcohol and diacids.

			MW
Nomenclature	A	R	(g/mol)
Bis(2-ethylhexyl)	—(CH2)2—	- 2-Ethylhexyl	342
succinate
Bis(2-ethylhexyl)	—(CH2)3—	- 2-Ethylhexyl	356
glutarate
Dicyclohexyl	—(CH2)4—	- Cyclohexyl	310
adipate
Bis(2-ethylhexyl)	—CH2—CH2—CH(CH3)—	- 2-Ethylhexyl	370
2-methylglutarate
Dicyclohexyl	—CH2—CH2—CH(CH3)—	- Cyclohexyl	310
2-methylglutarate
Bis(2-ethylhexyl)	—CH2—CH(CH2CH3)—	- 2-Ethylhexyl	370
2-ethylsuccinate
Dicyclohexyl	—CH2—CH(CH2CH3)—	- Cyclohexyl	310
2-ethylsuccinate
Plast Fast =	95%:	- Cyclohexyl	310
mixture of 95%	—CH2—CH2—CH(CH3)—
dicyclohexyl	5%:
methylglutarate	—CH2—CH(CH2CH3)—
and 5% dicyclo-
hexyl 2-
ethylsuccinate

Synthesis of Compounds Based on PVC: Plasticization

All the plasticizers used for the tests with the PVC resins under different formulations are summarized in table 2.

TABLE 2
description of the plasticizers

			MW
Plasticizer	Manufacturer	Chemical name	(g/mol)
DEHP	Arkema	Di(2-ethylhexyl) phthalate	390
DINP	BASF	Diisononyl phthalate	418
DINCH	BASF	1,2-Cyclohexanedicarboxylic	425
		acid, diisononyl ester
DOTP	Eastman	Di(2-ethylhexyl) terephthalate	390
Nexo E01	Nexoleum	Methyl epoxy soyate	327
Benzoflex	Eastman	Mixture of benzoate esters	350
2088		(78-80%) and dipropylene
		glycol dibenzoate (18-20%)
Jayflex MB10	Exxon	Isodecyl monobenzoate	262
Plast Fast	Solvay	2-Methylglutarate diester	310

A comparative assessment of the performances of the plasticizers studied was carried out for each formulation. The criteria for classifying the performance of the plasticizers, in comparison with DINP, are classified as follows:

	0: idem	−0.5: slightly poorer	0.5: slightly better
		−1: poorer	1: better
		−2: bad	2: excellent
		−3: very bad	3: outstanding

Example 2

Each plasticizer listed in table 2 makes it possible to produce transparent formulations according to table 3 below, using a mixer of medium-speed mixer type at a temperature of 23° C.

TABLE 3
Recipe for PVC pastes (compact transparent layers):

	Starting materials	Amount (phr)

	SolVin ® 382NG	100
	Plasticizer	50
	Baerostab ® NT 306	2.5
	(Ca/Zn)

The comparison of the data obtained for the formulations synthesized, the plasticizer being modified on each occasion, are summarized in table 4.

TABLES 4a to 4i
evaluations and comparison of the properties
4a- Shore A: Hardness (on 6 mm plaques)

		Curings in the oven
	Plasticizer	(cutting)	Pressed films
	DEHP	67	75
	DINP	72	78
	DINCH	74.5	84
	DOTP	71	76
	Nexo E01	66	70
	Plast Fast	65	68
	MB10/DINP	68	71
	2088/DINP	71	73

4b- Viscosity at low rate gradient (Eta = 1.4 s−1)

	Plasticizer	t 0	t 0 + 24 h
	DEHP	4.4	9.6
	DINP	3.6	15.7
	DINCH	2.0	3.4
	DOTP	3.4	3.4
	Nexo E01	2.4	4.0
	Plast Fast	2.7	5.9
	MB10/DINP	1.6	36.0
	2088/DINP	14.4	13.4

4c- Relative gelation rate (ARES rheometer, plate-plate,

1 rad/s, temperatures from 23 to 100° C., rise of 3° C./min)

	Plasticizers	Gelation
	DEHP	0.75
	DINP	0
	DINCH	−1.5
	DOTP	−0.75
	Nexo E01	1.25
	Plast Fast	2.5
	MB10	1
	2088	2

4d- Loss in weight (%) at 100° C. - ventilated oven

	Plasticizer	After 4 days	After 7 days
	DEHP	9.85	19.4
	DINP	2.3	3.8
	DINCH	6.3	10.2
	DOTP	3.7	7.55
	Nexo E01	12.4	15.8
	Plast Fast	20.7	24.6
	MB10/DINP	16.4	17.6
	2088/DINP	4.7	6.9

4e- Color, gloss and transparency of the PVC

films (0.7 mm, 190° C., 2 min)

		Yellowness
	Plasticizer	index	Gloss	Transparency
	DEHP	8.4	29.3	83.7
	DINP	8.7	30.6	86.5
	DINCH	8.1	35.5	85.35
	DOTP	7.75	30.05	81.7
	Nexo E01	17.8	22.6	74.1
	Plast Fast	11.4	29.1	87.9
	MB10/DINP	8.0	23.2	82.6
	2088/DINP	9.3	25.8	82.4

4f- Debubbling

	Plasticizer	Column height (ml)	Time (s)
	DEHP	98	49.5
	DINP	100.5	53
	DINCH	100	60.5
	DOTP	93	29
	Nexo E01	29	23
	Plast Fast	94	37
	MB10/DINP	83	22
	2088/DINP	100	100

4g- Thermal stability (DHC at 180° C. and Metrastat at 197° C.)

	Plasticizer	DHC (min)	Metrastat (min)
	DEHP	25	10
	DINP	24.2	15
	DINCH	28.3	11.6
	DOTP	25.8	15.5
	Nexo E01	152	27
	Plast Fast	27	19.15
	MB10/DINP	25.8	19.3
	2088/DINP	30.6	18.5

4h- Compatibility plasticizer with PVC ASTM D3291-92

Plasticizer	0	1 Day	1 Week	2 Weeks	4 Weeks	8 Weeks
DINP	0	0	0	0	0	0
Plast Fast	0	0	0	0	0	0

4i- Migration of the PVC film (0.7 mm, 190° C., 2 min)

		Date of
		manufacture of the
Plasticizer	Migration	film	Comments
DEHP	0	Sept-09	dry sample
DINP	0	Sept-09	dry sample
DINCH	0	Sept-09	dry sample
DOTP	0	Apr-10	dry sample
Nexo E01	−0.5	Apr-10	presence of exudation on
			the paper
Plast Fast	0	Nov-12	dry sample
MB10/DINP	0	August-10	dry sample
2088/DINP	0	August-10	dry sample

The best performances which emerge for the “Plast Fast” plasticizer are the gelation and the debubbling. This phenomenon is illustrated in FIG. 1 and the photographs taken for the debubbling are presented in FIG. 2. In FIG. 1, it should be understood that the photographs of the 2nd column are taken after 1 minute of resumption of the mixing (that is to say, reincorporation of air). The same applies for the photographs of the 3rd column, after 5 minutes

The classification of the plasticizers according to the grades assigned are summarized in table 5.

TABLE 5
Summary of the properties obtained with the plasticizers in the transparent
PVC paste formulations

Thermal

Loss in

Plasticizer

Viscosity

Aging

Gelation

Efficacy

Debubbling

stability

Color

Transp.

Gloss

weight

Migration

Score

DEHP	0	0.5	0.75	1	0	−0.125	0	0	0	−2	0	0.125
DINP	0	0	0	0	0	0	0	0	0	0	0	0
DINCH	0.5	1.25	−1.5	−0.75	0	0	0	0	0.75	−1	0	−0.75
DOTP	0	1.25	−0.75	0.25	0	0	0	−0.5	0	−0.75	0	−0.5
Nexo E01	0	1	1.25	1.375	1	3	−1.5	−0.75	−0.5	−1.5	−0.5	2.875
Plast Fast	0.25	0.75	2.5	1.5	0.75	0.25	−0.5	0	0	−2.75	0	2.75
MB10/DINP	0.75	−0.5	1	1.125	−0.5	0.125	0	−0.25	−0.5	−1.75	0	−0.5
2088/DINP	−2	0	2	0.7	−1.5	0.25	−0.25	−0.25	−0.25	−0.5	0	−1.81

Example 3

Foam formulations corresponding to table 6 were produced with each plasticizer of table 2 in a mixer of medium-speed type.

TABLE 6
Recipe for PVC pastes - foam-type formulations (expanded layers):

	Starting materials	Amount (phr)

	SolVin 367NK	100
	Plasticizer	62
	CaCO3 (15 mm)	40
	Porofor ® ADC (50%) + DINP	6
	Baerostab ® KK42 (K/Zn)	2.0

The comparison of the data obtained for the formulations synthesized, the plasticizer being modified on each occasion, are summarized in table 7.

TABLES 7a and 7b
evaluations and comparison of the properties
7a- Rheology and aging of the paste at low rate gradient (Eta = 1.4 s−1)

Plasticizer	t 0	t 0 + 24 h
DEHP	9.1	8.5
DINP	7.2	6.5
DINCH	7.4	5.6
DOTP	10.6	7.5
Nexo E01	3.8	5.0
Plast Fast	11.4	11.7
MB10/DINP	2.1	2.5
2088/DINP	6.9	7.3

7b- Density, color, rate of expansion, and cell quality

(thickness 0.35 mm, 2 min at 200° C.)

	Density	Rate of	Yellowness	Cell
Plasticizer	(g/cm3)	expansion	index	quality
DEHP	0.25	5.1	12.9	Very good
DINP	0.25	5.27	14.19	Very good
DINCH	0.25	5.2	15.2	Very good
DOTP	0.26	5.2	11.25	Very good
Nexo E01	0.24	5.6	47.7	Moderate
Plast Fast	0.21	6.3	19.4	Good
MB10/DINP	0.25	5.4	14	Very good
2088/DINP	0.25	5.2	16.2	Very good

The classification of the plasticizers according to the grades assigned are summarized in table 8.

TABLE 8
Summary of the properties obtained with the plasticizers
in the PVC foam formulations

					Rate	Cell
Plasticizer	Viscosity	Aging	Color	Density	exp	quality	Score

DEHP	−0.5	0	0.5	0	0	0	0
DINP	0	0	0	0	0	0	0
DINCH	0	0	0	0	0	0	0
DOTP	−0.75	0	0.5	0	0	0	−0.25
Nexo E01	1	0	−2.5	0.5	0.5	−1	−1.5
Plast Fast	−0.75	0	−0.75	1	1.25	−0.5	0.25
MB10/	1.5	0	0	0	0.25	0	1.75
DINP
2088/	0	0	0	−0.25	0	0	−0.25
DINP

The general comparison of these 2 formulations allows us to have the result of the overall performance of the plasticizers. The mean of the score of the transparent layers and the score of the foam layers gives us the overall performance score for each plasticizer and thus allows us to compare them. The total score of the performances evaluated is given in table 9.

TABLE 9
Total score of the performances of each plasticizer.

Plasticizer	Score transparent layers	Score foam layers	Total score

DEHP	0.125	0	0.125
DINP	0	0	0
DINCH	−0.75	0	−0.75
DOTP	−0.5	−0.25	−0.75
Nexo E01	2.875	−1.5	1.38
Plast Fast	2.75	0.25	3
MB10/DINP	−0.5	1.75	1.25
2088/DINP	−1.8125	−0.25	−2.06

On average, the Plast Fast exhibits a good performance for the 2 recipes tested; it has the highest score in comparison with the other plasticizers. This plasticizer rapidly gels, has a very low viscosity and ages very well. Efficient debubbling is one of these leading characteristics. The foams prepared with this plasticizer have low densities, a high rate of expansion and excellent qualities.