Injection-molded flexible tube based on high-density polyethylene

Abstract

The present invention relates to a tube having a dispensing head and a flexible skirt. The skirt and the dispensing head include a single wall manufactured in a single injection-molding operation in an injection mold. According to the invention, the wall is made of a material whose base constituent is a high-density polyethylene (HDPE) or a mixture of polymers, at least one of which is a high-density polyethylene representing from 5% to 100% by weight of the polymers constituting the wall. The present invention also relates to a process for manufacturing such a tube.

Claims

1. A one-piece tube having a dispensing head and a flexible skirt, the skirt and the dispensing head being manufactured in a single injection-molding operation in an injection mold, wherein the skirt and the dispensing head consist of a single wall forming the one-piece tube, and wherein the wall is made of a material whose base constituent is a high-density polyethylene (HDPE) or a mixture of polymers, at least one of which is a high-density polyethylene representing at least 5% by weight of the polymers constituting the wall.

2. The tube according to claim 1, in which the wall is made of a material whose base constituent is HDPE or a mixture of polymers, at least one of which is a high-density polyethylene representing at least 15% by weight of the polymers constituting the wall.

3. The tube according to claim 1, in which the high-density polyethylene (HDPE) has a density at least equal to 0.945 g/cm.sup.3 and a melt flow index (MFI) measured according to standard ISO 1133 of between 1 and 4 g/ 10 minutes.

4. The tube according to claim 1, wherein the mixture of polymers comprises at least one low-density polyethylene (LDPE).

5. The tube according to claim 4, wherein the low-density polyethylene has a density of between 0.900 g/cm.sup.3 and 0.940 g/cm.sup.3, and a melt flow index of between 4 and 9 g/ 10 minutes.

6. The tube according to claim 5, wherein the low-density polyethylene is a linear polyethylene.

7. The tube according to claim 6, wherein the wall includes polymers consisting of polyethylenes.

8. The tube according to claim 7, in which the skirt has a wall thickness of between 0.3 mm and 0.4 mm and a length of between 50 mm and 60 mm.

9. The tube according to claim 7, wherein the skirt has a length L within the range of L=600E160, wherein E is the thickness of the wall and dimensions L and E being expressed in mm.

Description

EXAMPLES

(1) Tests:

(2) Water Impermeability Test:

(3) The water impermeability test consists in placing the tubes, filled beforehand with the test product and welded, in an oven maintained at a given temperature for a given period of time.

(4) The weight of the cream is measured before placing the tube in the oven, and then after the test period.

(5) The evaporation of the water vapor corresponds to the weight loss of the cream between the two measurements.

(6) This evaporation is always expressed as a relative value, by calculation of the ratio of the weight after the test period relative to the weight of the cream before testing.

(7) The most usual implementation conditions and acceptance limit conditions are as follows:

(8) oven temperature: 45 C. or 50 C.;

(9) exposure time: 336 or 1440 or 2016 hours;

(10) acceptance limit weight loss of 2% to 9% depending on the exposure temperatures and times selected.

(11) Test for Measurement of the Resistance to Surfactants

(12) (Measurement of the Resistance to Stress Cracking)

(13) The test of resistance of the polymer to stress cracking consists in:

(14) filling a sample of tubes with a solution of tridecyl ether diluted to 0.5% in distilled water and welding the tube;

(15) placing the tubes in an oven at 55 C. for 24 hours; and

(16) observing each tube after the test by placing the wall under pressure, to detect any leakage or splitting.

(17) Measurement of the Weight Loss

(18) The empty tube is weighed;

(19) The filled tube is weighed before being dried in oven;

(20) The filled tube is weighed after being dried in oven;

(21) The weight loss of the cream during the passage of the tube into the oven is calculated by subtracting

(22) The weight loss measures the evaporation of the cream by migration through the wall during the test period, and thus qualifies the barrier property of the tube wall.

Results

Example 1

According to the Prior Art

(23) Sample 1:

(24) 10 injection-molded LDPE tubes made according to WO 01/68355

(25) LDPE polymer usedLLDP Dowlex 2035density 0.919 g/cm.sup.3MFI: 6.0 g/10 minutes (190 C./2-16 kg)

(26) Diameter of the tubes: 19 mm

Example 2

According to the Invention

(27) Sample 2:

(28) 10 injection-molded tubes according to the process of the invention

(29) Polymers used:

(30) 33% LDPELLDP Dowlex 2035;

(31) 67% HDPEHDPE Dow 80255density 0.956 g/cm.sup.3MFI 2 g/10 minutes (190 C./2-16 kg).

(32) Diameter of the Tubes: 19 Mm

(33) The tubes of sample 1 and those of sample 2 were subjected to the tests of resistance to stress cracking and of hot impermeability (weight loss). The results are presented in Table 1 below:

(34) TABLE-US-00001 TABLE 1 Test Sample 1 Sample 2 Resistance to surfactants according Compliant Compliant to the preceding paragraph Weight loss 5.00% 3.5% cream tested Vichy Liftactive temperature 45 C. exposure time 1440 hours. amount packaged 5 ml Weight of the empty tube 2.3 g 1.65 g (tube diameter 19)

(35) These results show that:

(36) the weight loss is improved by 30% on passing from sample 1 (according to the prior art) to sample 2 (according to the invention);

(37) the weight of the empty tube is reduced by 28% on passing from sample 1 (according to the prior art) to sample 2 (according to the invention).

Example 3

According to the Prior Art

(38) Sample 3:

(39) 10 injection-molded LDPE tubes made according to WO 01/68355

(40) LDPE polymer usedLLDP Dowlex 2035density 0.919 g/cm.sup.3

(41) Wall thickness of the tubes: 0.45 mm

(42) Diameter of the tubes: 16 mm

Example 4

According to the Invention

(43) Sample 4:

(44) 10 injection-molded tubes according to the process of the invention

(45) Polymers used:

(46) 90% LDPELLDP Dowlex 2035density 0.919 g/cm3

(47) 10% HDPEHDPE Plurell 6541 (BASELL)density 0.955 g/cm3

(48) Wall thickness of the tubes: 0.45 mm

(49) Diameter of the tubes: 16 mm

Example 5

According to the Invention

(50) Sample 5:

(51) 10 injection-molded tubes according to the process of the invention

(52) Polymers used:

(53) 80% LDPELLDP Dowlex 2035density 0.919 g/cm3

(54) 20% HDPEHDPE Plurell 6541 (BASELL)density 0.955 g/cm3

(55) Wall thickness of the tubes: 0.45 mm

(56) Diameter of the tubes: 16 mm

Example 6

According to the Invention

(57) Sample 6:

(58) 10 injection-molded tubes according to the process of the invention

(59) Polymers used:

(60) 33% LDPELLDP Dowlex 2035density 0.919 g/cm3

(61) 67% HDPEHDPE Plurell 6541 (BASELL)density 0.955 g/cm3

(62) Wall thickness of the tubes: 0.33 mm

(63) Diameter of the tubes: 16 mm

Example 7

According to the Invention

(64) Sample 7:

(65) 10 injection-molded tubes according to the process of the invention

(66) Polymer used:

(67) 100% HDPEHDPE Plurell 6541 (BASELL)density 0.955 g/cm3

(68) Wall thickness of the tubes: 0.33 mm

(69) Diameter of the tubes: 16 mm

(70) The tubes of samples 3 to 7 were subjected to the tests of resistance to stress cracking and of hot impermeability (weight loss). The results are presented in Table 2 below:

(71) TABLE-US-00002 TABLE 2 Weight loss cream tested Vichy Liftactive Characterization temperature 45 C. of the tube exposure time Wall Weight Resistance to 1440 hours, Samples thickness of tube surfactants amount packaged 5 ml Sample 3 0.45 mm 1.85 g Compliant 9.50% Sample 4 0.45 mm 1.85 g Compliant 7.60% Sample 5 0.45 mm 1.85 g Compliant 6.50% Sample 6 0.33 mm 1.35 g Compliant 5.00% Sample 7 0.33 mm 1.35 g Compliant 3.90%
Comments of the Results

(72) The barrier properties are improved to a considerable extent with the rising rate of HDPE in the mixture, the weight loss moving from 9.50% when the tube wall is 100% LDPE to 3.90% when the tube wall is 100% HDPE, thus an improvement of 245% barrier properties.

(73) This performance is all the more remarkable that the weight loss of 3.90% is obtained in a tube with a wall of 0.33 mm, against a 9.50% weight loss in a tube with of a wall of 0.45 mm, thus a correlative defatting of the wall by 27%, resulting in a weight gain for the vacuum tube of 50 grams, or also a 27% gain.

(74) The use of HDPE simultaneously multiplies by 2.5 the barrier properties, reduce the curb weight of the tube, thus lowering the cost and meet ecological demand of the decrease in the consumption of raw materials (oil).

(75) The observed results support a finding that improved barrier properties is directly proportional to the proportion of HDPE in the blend of 0% to 100% HDPE.